Restoring authorship annotation for <monory@yandex-team.ru>. Commit 1 of 2.

50 files changed, 23713 insertions, 23713 deletions

diff --git a/contrib/python/tornado/tornado-4/.dist-info/METADATA b/contrib/python/tornado/tornado-4/.dist-info/METADATA
index 3c02bd9be2..eda127b0ff 100644
--- a/contrib/python/tornado/tornado-4/.dist-info/METADATA
+++ b/contrib/python/tornado/tornado-4/.dist-info/METADATA
@@ -1,68 +1,68 @@
-Metadata-Version: 1.1
-Name: tornado
-Version: 4.5.3
-Summary: Tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed.
-Home-page: http://www.tornadoweb.org/
-Author: Facebook
-Author-email: python-tornado@googlegroups.com
-License: http://www.apache.org/licenses/LICENSE-2.0
-Description: Tornado Web Server
-        ==================
-        
-        .. image:: https://badges.gitter.im/Join%20Chat.svg
-           :alt: Join the chat at https://gitter.im/tornadoweb/tornado
-           :target: https://gitter.im/tornadoweb/tornado?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge
-        
-        `Tornado <http://www.tornadoweb.org>`_ is a Python web framework and
-        asynchronous networking library, originally developed at `FriendFeed
-        <http://friendfeed.com>`_.  By using non-blocking network I/O, Tornado
-        can scale to tens of thousands of open connections, making it ideal for
-        `long polling <http://en.wikipedia.org/wiki/Push_technology#Long_Polling>`_,
-        `WebSockets <http://en.wikipedia.org/wiki/WebSocket>`_, and other
-        applications that require a long-lived connection to each user.
-        
-        Hello, world
-        ------------
-        
-        Here is a simple "Hello, world" example web app for Tornado:
-        
-        .. code-block:: python
-        
-            import tornado.ioloop
-            import tornado.web
-        
-            class MainHandler(tornado.web.RequestHandler):
-                def get(self):
-                    self.write("Hello, world")
-        
-            def make_app():
-                return tornado.web.Application([
-                    (r"/", MainHandler),
-                ])
-        
-            if __name__ == "__main__":
-                app = make_app()
-                app.listen(8888)
-                tornado.ioloop.IOLoop.current().start()
-        
-        This example does not use any of Tornado's asynchronous features; for
-        that see this `simple chat room
-        <https://github.com/tornadoweb/tornado/tree/stable/demos/chat>`_.
-        
-        Documentation
-        -------------
-        
-        Documentation and links to additional resources are available at
-        http://www.tornadoweb.org
-        
-Platform: UNKNOWN
-Classifier: License :: OSI Approved :: Apache Software License
-Classifier: Programming Language :: Python :: 2
-Classifier: Programming Language :: Python :: 2.7
-Classifier: Programming Language :: Python :: 3
-Classifier: Programming Language :: Python :: 3.3
-Classifier: Programming Language :: Python :: 3.4
-Classifier: Programming Language :: Python :: 3.5
-Classifier: Programming Language :: Python :: 3.6
-Classifier: Programming Language :: Python :: Implementation :: CPython
-Classifier: Programming Language :: Python :: Implementation :: PyPy
+Metadata-Version: 1.1 
+Name: tornado 
+Version: 4.5.3 
+Summary: Tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed. 
+Home-page: http://www.tornadoweb.org/ 
+Author: Facebook 
+Author-email: python-tornado@googlegroups.com 
+License: http://www.apache.org/licenses/LICENSE-2.0 
+Description: Tornado Web Server 
+        ================== 
+         
+        .. image:: https://badges.gitter.im/Join%20Chat.svg 
+           :alt: Join the chat at https://gitter.im/tornadoweb/tornado 
+           :target: https://gitter.im/tornadoweb/tornado?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge 
+         
+        `Tornado <http://www.tornadoweb.org>`_ is a Python web framework and 
+        asynchronous networking library, originally developed at `FriendFeed 
+        <http://friendfeed.com>`_.  By using non-blocking network I/O, Tornado 
+        can scale to tens of thousands of open connections, making it ideal for 
+        `long polling <http://en.wikipedia.org/wiki/Push_technology#Long_Polling>`_, 
+        `WebSockets <http://en.wikipedia.org/wiki/WebSocket>`_, and other 
+        applications that require a long-lived connection to each user. 
+         
+        Hello, world 
+        ------------ 
+         
+        Here is a simple "Hello, world" example web app for Tornado: 
+         
+        .. code-block:: python 
+         
+            import tornado.ioloop 
+            import tornado.web 
+         
+            class MainHandler(tornado.web.RequestHandler): 
+                def get(self): 
+                    self.write("Hello, world") 
+         
+            def make_app(): 
+                return tornado.web.Application([ 
+                    (r"/", MainHandler), 
+                ]) 
+         
+            if __name__ == "__main__": 
+                app = make_app() 
+                app.listen(8888) 
+                tornado.ioloop.IOLoop.current().start() 
+         
+        This example does not use any of Tornado's asynchronous features; for 
+        that see this `simple chat room 
+        <https://github.com/tornadoweb/tornado/tree/stable/demos/chat>`_. 
+         
+        Documentation 
+        ------------- 
+         
+        Documentation and links to additional resources are available at 
+        http://www.tornadoweb.org 
+         
+Platform: UNKNOWN 
+Classifier: License :: OSI Approved :: Apache Software License 
+Classifier: Programming Language :: Python :: 2 
+Classifier: Programming Language :: Python :: 2.7 
+Classifier: Programming Language :: Python :: 3 
+Classifier: Programming Language :: Python :: 3.3 
+Classifier: Programming Language :: Python :: 3.4 
+Classifier: Programming Language :: Python :: 3.5 
+Classifier: Programming Language :: Python :: 3.6 
+Classifier: Programming Language :: Python :: Implementation :: CPython 
+Classifier: Programming Language :: Python :: Implementation :: PyPy 
diff --git a/contrib/python/tornado/tornado-4/.dist-info/top_level.txt b/contrib/python/tornado/tornado-4/.dist-info/top_level.txt
index c3368dfa51..bf65ecf44d 100644
--- a/contrib/python/tornado/tornado-4/.dist-info/top_level.txt
+++ b/contrib/python/tornado/tornado-4/.dist-info/top_level.txt
@@ -1 +1 @@
-tornado
+tornado 
diff --git a/contrib/python/tornado/tornado-4/tornado/__init__.py b/contrib/python/tornado/tornado-4/tornado/__init__.py
index fa71bf6133..07b1f2ae0e 100644
--- a/contrib/python/tornado/tornado-4/tornado/__init__.py
+++ b/contrib/python/tornado/tornado-4/tornado/__init__.py
@@ -1,29 +1,29 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""The Tornado web server and tools."""
-
-from __future__ import absolute_import, division, print_function
-
-# version is a human-readable version number.
-
-# version_info is a four-tuple for programmatic comparison. The first
-# three numbers are the components of the version number.  The fourth
-# is zero for an official release, positive for a development branch,
-# or negative for a release candidate or beta (after the base version
-# number has been incremented)
-version = "4.5.3"
-version_info = (4, 5, 3, 0)
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""The Tornado web server and tools.""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+# version is a human-readable version number. 
+ 
+# version_info is a four-tuple for programmatic comparison. The first 
+# three numbers are the components of the version number.  The fourth 
+# is zero for an official release, positive for a development branch, 
+# or negative for a release candidate or beta (after the base version 
+# number has been incremented) 
+version = "4.5.3" 
+version_info = (4, 5, 3, 0) 
diff --git a/contrib/python/tornado/tornado-4/tornado/_locale_data.py b/contrib/python/tornado/tornado-4/tornado/_locale_data.py
index 6fa2c29742..cee11e7deb 100644
--- a/contrib/python/tornado/tornado-4/tornado/_locale_data.py
+++ b/contrib/python/tornado/tornado-4/tornado/_locale_data.py
@@ -1,85 +1,85 @@
-#!/usr/bin/env python
-# coding: utf-8
-#
-# Copyright 2012 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Data used by the tornado.locale module."""
-
-from __future__ import absolute_import, division, print_function
-
-LOCALE_NAMES = {
-    "af_ZA": {"name_en": u"Afrikaans", "name": u"Afrikaans"},
-    "am_ET": {"name_en": u"Amharic", "name": u"አማርኛ"},
-    "ar_AR": {"name_en": u"Arabic", "name": u"العربية"},
-    "bg_BG": {"name_en": u"Bulgarian", "name": u"Български"},
-    "bn_IN": {"name_en": u"Bengali", "name": u"বাংলা"},
-    "bs_BA": {"name_en": u"Bosnian", "name": u"Bosanski"},
-    "ca_ES": {"name_en": u"Catalan", "name": u"Català"},
-    "cs_CZ": {"name_en": u"Czech", "name": u"Čeština"},
-    "cy_GB": {"name_en": u"Welsh", "name": u"Cymraeg"},
-    "da_DK": {"name_en": u"Danish", "name": u"Dansk"},
-    "de_DE": {"name_en": u"German", "name": u"Deutsch"},
-    "el_GR": {"name_en": u"Greek", "name": u"Ελληνικά"},
-    "en_GB": {"name_en": u"English (UK)", "name": u"English (UK)"},
-    "en_US": {"name_en": u"English (US)", "name": u"English (US)"},
-    "es_ES": {"name_en": u"Spanish (Spain)", "name": u"Español (España)"},
-    "es_LA": {"name_en": u"Spanish", "name": u"Español"},
-    "et_EE": {"name_en": u"Estonian", "name": u"Eesti"},
-    "eu_ES": {"name_en": u"Basque", "name": u"Euskara"},
-    "fa_IR": {"name_en": u"Persian", "name": u"فارسی"},
-    "fi_FI": {"name_en": u"Finnish", "name": u"Suomi"},
-    "fr_CA": {"name_en": u"French (Canada)", "name": u"Français (Canada)"},
-    "fr_FR": {"name_en": u"French", "name": u"Français"},
-    "ga_IE": {"name_en": u"Irish", "name": u"Gaeilge"},
-    "gl_ES": {"name_en": u"Galician", "name": u"Galego"},
-    "he_IL": {"name_en": u"Hebrew", "name": u"עברית"},
-    "hi_IN": {"name_en": u"Hindi", "name": u"हिन्दी"},
-    "hr_HR": {"name_en": u"Croatian", "name": u"Hrvatski"},
-    "hu_HU": {"name_en": u"Hungarian", "name": u"Magyar"},
-    "id_ID": {"name_en": u"Indonesian", "name": u"Bahasa Indonesia"},
-    "is_IS": {"name_en": u"Icelandic", "name": u"Íslenska"},
-    "it_IT": {"name_en": u"Italian", "name": u"Italiano"},
-    "ja_JP": {"name_en": u"Japanese", "name": u"日本語"},
-    "ko_KR": {"name_en": u"Korean", "name": u"한국어"},
-    "lt_LT": {"name_en": u"Lithuanian", "name": u"Lietuvių"},
-    "lv_LV": {"name_en": u"Latvian", "name": u"Latviešu"},
-    "mk_MK": {"name_en": u"Macedonian", "name": u"Македонски"},
-    "ml_IN": {"name_en": u"Malayalam", "name": u"മലയാളം"},
-    "ms_MY": {"name_en": u"Malay", "name": u"Bahasa Melayu"},
-    "nb_NO": {"name_en": u"Norwegian (bokmal)", "name": u"Norsk (bokmål)"},
-    "nl_NL": {"name_en": u"Dutch", "name": u"Nederlands"},
-    "nn_NO": {"name_en": u"Norwegian (nynorsk)", "name": u"Norsk (nynorsk)"},
-    "pa_IN": {"name_en": u"Punjabi", "name": u"ਪੰਜਾਬੀ"},
-    "pl_PL": {"name_en": u"Polish", "name": u"Polski"},
-    "pt_BR": {"name_en": u"Portuguese (Brazil)", "name": u"Português (Brasil)"},
-    "pt_PT": {"name_en": u"Portuguese (Portugal)", "name": u"Português (Portugal)"},
-    "ro_RO": {"name_en": u"Romanian", "name": u"Română"},
-    "ru_RU": {"name_en": u"Russian", "name": u"Русский"},
-    "sk_SK": {"name_en": u"Slovak", "name": u"Slovenčina"},
-    "sl_SI": {"name_en": u"Slovenian", "name": u"Slovenščina"},
-    "sq_AL": {"name_en": u"Albanian", "name": u"Shqip"},
-    "sr_RS": {"name_en": u"Serbian", "name": u"Српски"},
-    "sv_SE": {"name_en": u"Swedish", "name": u"Svenska"},
-    "sw_KE": {"name_en": u"Swahili", "name": u"Kiswahili"},
-    "ta_IN": {"name_en": u"Tamil", "name": u"தமிழ்"},
-    "te_IN": {"name_en": u"Telugu", "name": u"తెలుగు"},
-    "th_TH": {"name_en": u"Thai", "name": u"ภาษาไทย"},
-    "tl_PH": {"name_en": u"Filipino", "name": u"Filipino"},
-    "tr_TR": {"name_en": u"Turkish", "name": u"Türkçe"},
-    "uk_UA": {"name_en": u"Ukraini ", "name": u"Українська"},
-    "vi_VN": {"name_en": u"Vietnamese", "name": u"Tiếng Việt"},
-    "zh_CN": {"name_en": u"Chinese (Simplified)", "name": u"中文(简体)"},
-    "zh_TW": {"name_en": u"Chinese (Traditional)", "name": u"中文(繁體)"},
-}
+#!/usr/bin/env python 
+# coding: utf-8 
+# 
+# Copyright 2012 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Data used by the tornado.locale module.""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+LOCALE_NAMES = { 
+    "af_ZA": {"name_en": u"Afrikaans", "name": u"Afrikaans"}, 
+    "am_ET": {"name_en": u"Amharic", "name": u"አማርኛ"}, 
+    "ar_AR": {"name_en": u"Arabic", "name": u"العربية"}, 
+    "bg_BG": {"name_en": u"Bulgarian", "name": u"Български"}, 
+    "bn_IN": {"name_en": u"Bengali", "name": u"বাংলা"}, 
+    "bs_BA": {"name_en": u"Bosnian", "name": u"Bosanski"}, 
+    "ca_ES": {"name_en": u"Catalan", "name": u"Català"}, 
+    "cs_CZ": {"name_en": u"Czech", "name": u"Čeština"}, 
+    "cy_GB": {"name_en": u"Welsh", "name": u"Cymraeg"}, 
+    "da_DK": {"name_en": u"Danish", "name": u"Dansk"}, 
+    "de_DE": {"name_en": u"German", "name": u"Deutsch"}, 
+    "el_GR": {"name_en": u"Greek", "name": u"Ελληνικά"}, 
+    "en_GB": {"name_en": u"English (UK)", "name": u"English (UK)"}, 
+    "en_US": {"name_en": u"English (US)", "name": u"English (US)"}, 
+    "es_ES": {"name_en": u"Spanish (Spain)", "name": u"Español (España)"}, 
+    "es_LA": {"name_en": u"Spanish", "name": u"Español"}, 
+    "et_EE": {"name_en": u"Estonian", "name": u"Eesti"}, 
+    "eu_ES": {"name_en": u"Basque", "name": u"Euskara"}, 
+    "fa_IR": {"name_en": u"Persian", "name": u"فارسی"}, 
+    "fi_FI": {"name_en": u"Finnish", "name": u"Suomi"}, 
+    "fr_CA": {"name_en": u"French (Canada)", "name": u"Français (Canada)"}, 
+    "fr_FR": {"name_en": u"French", "name": u"Français"}, 
+    "ga_IE": {"name_en": u"Irish", "name": u"Gaeilge"}, 
+    "gl_ES": {"name_en": u"Galician", "name": u"Galego"}, 
+    "he_IL": {"name_en": u"Hebrew", "name": u"עברית"}, 
+    "hi_IN": {"name_en": u"Hindi", "name": u"हिन्दी"}, 
+    "hr_HR": {"name_en": u"Croatian", "name": u"Hrvatski"}, 
+    "hu_HU": {"name_en": u"Hungarian", "name": u"Magyar"}, 
+    "id_ID": {"name_en": u"Indonesian", "name": u"Bahasa Indonesia"}, 
+    "is_IS": {"name_en": u"Icelandic", "name": u"Íslenska"}, 
+    "it_IT": {"name_en": u"Italian", "name": u"Italiano"}, 
+    "ja_JP": {"name_en": u"Japanese", "name": u"日本語"}, 
+    "ko_KR": {"name_en": u"Korean", "name": u"한국어"}, 
+    "lt_LT": {"name_en": u"Lithuanian", "name": u"Lietuvių"}, 
+    "lv_LV": {"name_en": u"Latvian", "name": u"Latviešu"}, 
+    "mk_MK": {"name_en": u"Macedonian", "name": u"Македонски"}, 
+    "ml_IN": {"name_en": u"Malayalam", "name": u"മലയാളം"}, 
+    "ms_MY": {"name_en": u"Malay", "name": u"Bahasa Melayu"}, 
+    "nb_NO": {"name_en": u"Norwegian (bokmal)", "name": u"Norsk (bokmål)"}, 
+    "nl_NL": {"name_en": u"Dutch", "name": u"Nederlands"}, 
+    "nn_NO": {"name_en": u"Norwegian (nynorsk)", "name": u"Norsk (nynorsk)"}, 
+    "pa_IN": {"name_en": u"Punjabi", "name": u"ਪੰਜਾਬੀ"}, 
+    "pl_PL": {"name_en": u"Polish", "name": u"Polski"}, 
+    "pt_BR": {"name_en": u"Portuguese (Brazil)", "name": u"Português (Brasil)"}, 
+    "pt_PT": {"name_en": u"Portuguese (Portugal)", "name": u"Português (Portugal)"}, 
+    "ro_RO": {"name_en": u"Romanian", "name": u"Română"}, 
+    "ru_RU": {"name_en": u"Russian", "name": u"Русский"}, 
+    "sk_SK": {"name_en": u"Slovak", "name": u"Slovenčina"}, 
+    "sl_SI": {"name_en": u"Slovenian", "name": u"Slovenščina"}, 
+    "sq_AL": {"name_en": u"Albanian", "name": u"Shqip"}, 
+    "sr_RS": {"name_en": u"Serbian", "name": u"Српски"}, 
+    "sv_SE": {"name_en": u"Swedish", "name": u"Svenska"}, 
+    "sw_KE": {"name_en": u"Swahili", "name": u"Kiswahili"}, 
+    "ta_IN": {"name_en": u"Tamil", "name": u"தமிழ்"}, 
+    "te_IN": {"name_en": u"Telugu", "name": u"తెలుగు"}, 
+    "th_TH": {"name_en": u"Thai", "name": u"ภาษาไทย"}, 
+    "tl_PH": {"name_en": u"Filipino", "name": u"Filipino"}, 
+    "tr_TR": {"name_en": u"Turkish", "name": u"Türkçe"}, 
+    "uk_UA": {"name_en": u"Ukraini ", "name": u"Українська"}, 
+    "vi_VN": {"name_en": u"Vietnamese", "name": u"Tiếng Việt"}, 
+    "zh_CN": {"name_en": u"Chinese (Simplified)", "name": u"中文(简体)"}, 
+    "zh_TW": {"name_en": u"Chinese (Traditional)", "name": u"中文(繁體)"}, 
+} 
diff --git a/contrib/python/tornado/tornado-4/tornado/auth.py b/contrib/python/tornado/tornado-4/tornado/auth.py
index f02d289808..edd1801731 100644
--- a/contrib/python/tornado/tornado-4/tornado/auth.py
+++ b/contrib/python/tornado/tornado-4/tornado/auth.py
@@ -1,1154 +1,1154 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""This module contains implementations of various third-party
-authentication schemes.
-
-All the classes in this file are class mixins designed to be used with
-the `tornado.web.RequestHandler` class.  They are used in two ways:
-
-* On a login handler, use methods such as ``authenticate_redirect()``,
-  ``authorize_redirect()``, and ``get_authenticated_user()`` to
-  establish the user's identity and store authentication tokens to your
-  database and/or cookies.
-* In non-login handlers, use methods such as ``facebook_request()``
-  or ``twitter_request()`` to use the authentication tokens to make
-  requests to the respective services.
-
-They all take slightly different arguments due to the fact all these
-services implement authentication and authorization slightly differently.
-See the individual service classes below for complete documentation.
-
-Example usage for Google OAuth:
-
-.. testcode::
-
-    class GoogleOAuth2LoginHandler(tornado.web.RequestHandler,
-                                   tornado.auth.GoogleOAuth2Mixin):
-        @tornado.gen.coroutine
-        def get(self):
-            if self.get_argument('code', False):
-                user = yield self.get_authenticated_user(
-                    redirect_uri='http://your.site.com/auth/google',
-                    code=self.get_argument('code'))
-                # Save the user with e.g. set_secure_cookie
-            else:
-                yield self.authorize_redirect(
-                    redirect_uri='http://your.site.com/auth/google',
-                    client_id=self.settings['google_oauth']['key'],
-                    scope=['profile', 'email'],
-                    response_type='code',
-                    extra_params={'approval_prompt': 'auto'})
-
-.. testoutput::
-   :hide:
-
-
-.. versionchanged:: 4.0
-   All of the callback interfaces in this module are now guaranteed
-   to run their callback with an argument of ``None`` on error.
-   Previously some functions would do this while others would simply
-   terminate the request on their own.  This change also ensures that
-   errors are more consistently reported through the ``Future`` interfaces.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import base64
-import binascii
-import functools
-import hashlib
-import hmac
-import time
-import uuid
-
-from tornado.concurrent import TracebackFuture, return_future, chain_future
-from tornado import gen
-from tornado import httpclient
-from tornado import escape
-from tornado.httputil import url_concat
-from tornado.log import gen_log
-from tornado.stack_context import ExceptionStackContext
-from tornado.util import unicode_type, ArgReplacer, PY3
-
-if PY3:
-    import urllib.parse as urlparse
-    import urllib.parse as urllib_parse
-    long = int
-else:
-    import urlparse
-    import urllib as urllib_parse
-
-
-class AuthError(Exception):
-    pass
-
-
-def _auth_future_to_callback(callback, future):
-    try:
-        result = future.result()
-    except AuthError as e:
-        gen_log.warning(str(e))
-        result = None
-    callback(result)
-
-
-def _auth_return_future(f):
-    """Similar to tornado.concurrent.return_future, but uses the auth
-    module's legacy callback interface.
-
-    Note that when using this decorator the ``callback`` parameter
-    inside the function will actually be a future.
-    """
-    replacer = ArgReplacer(f, 'callback')
-
-    @functools.wraps(f)
-    def wrapper(*args, **kwargs):
-        future = TracebackFuture()
-        callback, args, kwargs = replacer.replace(future, args, kwargs)
-        if callback is not None:
-            future.add_done_callback(
-                functools.partial(_auth_future_to_callback, callback))
-
-        def handle_exception(typ, value, tb):
-            if future.done():
-                return False
-            else:
-                future.set_exc_info((typ, value, tb))
-                return True
-        with ExceptionStackContext(handle_exception):
-            f(*args, **kwargs)
-        return future
-    return wrapper
-
-
-class OpenIdMixin(object):
-    """Abstract implementation of OpenID and Attribute Exchange.
-
-    Class attributes:
-
-    * ``_OPENID_ENDPOINT``: the identity provider's URI.
-    """
-    @return_future
-    def authenticate_redirect(self, callback_uri=None,
-                              ax_attrs=["name", "email", "language", "username"],
-                              callback=None):
-        """Redirects to the authentication URL for this service.
-
-        After authentication, the service will redirect back to the given
-        callback URI with additional parameters including ``openid.mode``.
-
-        We request the given attributes for the authenticated user by
-        default (name, email, language, and username). If you don't need
-        all those attributes for your app, you can request fewer with
-        the ax_attrs keyword argument.
-
-        .. versionchanged:: 3.1
-           Returns a `.Future` and takes an optional callback.  These are
-           not strictly necessary as this method is synchronous,
-           but they are supplied for consistency with
-           `OAuthMixin.authorize_redirect`.
-        """
-        callback_uri = callback_uri or self.request.uri
-        args = self._openid_args(callback_uri, ax_attrs=ax_attrs)
-        self.redirect(self._OPENID_ENDPOINT + "?" + urllib_parse.urlencode(args))
-        callback()
-
-    @_auth_return_future
-    def get_authenticated_user(self, callback, http_client=None):
-        """Fetches the authenticated user data upon redirect.
-
-        This method should be called by the handler that receives the
-        redirect from the `authenticate_redirect()` method (which is
-        often the same as the one that calls it; in that case you would
-        call `get_authenticated_user` if the ``openid.mode`` parameter
-        is present and `authenticate_redirect` if it is not).
-
-        The result of this method will generally be used to set a cookie.
-        """
-        # Verify the OpenID response via direct request to the OP
-        args = dict((k, v[-1]) for k, v in self.request.arguments.items())
-        args["openid.mode"] = u"check_authentication"
-        url = self._OPENID_ENDPOINT
-        if http_client is None:
-            http_client = self.get_auth_http_client()
-        http_client.fetch(url, functools.partial(
-            self._on_authentication_verified, callback),
-            method="POST", body=urllib_parse.urlencode(args))
-
-    def _openid_args(self, callback_uri, ax_attrs=[], oauth_scope=None):
-        url = urlparse.urljoin(self.request.full_url(), callback_uri)
-        args = {
-            "openid.ns": "http://specs.openid.net/auth/2.0",
-            "openid.claimed_id":
-            "http://specs.openid.net/auth/2.0/identifier_select",
-            "openid.identity":
-            "http://specs.openid.net/auth/2.0/identifier_select",
-            "openid.return_to": url,
-            "openid.realm": urlparse.urljoin(url, '/'),
-            "openid.mode": "checkid_setup",
-        }
-        if ax_attrs:
-            args.update({
-                "openid.ns.ax": "http://openid.net/srv/ax/1.0",
-                "openid.ax.mode": "fetch_request",
-            })
-            ax_attrs = set(ax_attrs)
-            required = []
-            if "name" in ax_attrs:
-                ax_attrs -= set(["name", "firstname", "fullname", "lastname"])
-                required += ["firstname", "fullname", "lastname"]
-                args.update({
-                    "openid.ax.type.firstname":
-                    "http://axschema.org/namePerson/first",
-                    "openid.ax.type.fullname":
-                    "http://axschema.org/namePerson",
-                    "openid.ax.type.lastname":
-                    "http://axschema.org/namePerson/last",
-                })
-            known_attrs = {
-                "email": "http://axschema.org/contact/email",
-                "language": "http://axschema.org/pref/language",
-                "username": "http://axschema.org/namePerson/friendly",
-            }
-            for name in ax_attrs:
-                args["openid.ax.type." + name] = known_attrs[name]
-                required.append(name)
-            args["openid.ax.required"] = ",".join(required)
-        if oauth_scope:
-            args.update({
-                "openid.ns.oauth":
-                "http://specs.openid.net/extensions/oauth/1.0",
-                "openid.oauth.consumer": self.request.host.split(":")[0],
-                "openid.oauth.scope": oauth_scope,
-            })
-        return args
-
-    def _on_authentication_verified(self, future, response):
-        if response.error or b"is_valid:true" not in response.body:
-            future.set_exception(AuthError(
-                "Invalid OpenID response: %s" % (response.error or
-                                                 response.body)))
-            return
-
-        # Make sure we got back at least an email from attribute exchange
-        ax_ns = None
-        for name in self.request.arguments:
-            if name.startswith("openid.ns.") and \
-                    self.get_argument(name) == u"http://openid.net/srv/ax/1.0":
-                ax_ns = name[10:]
-                break
-
-        def get_ax_arg(uri):
-            if not ax_ns:
-                return u""
-            prefix = "openid." + ax_ns + ".type."
-            ax_name = None
-            for name in self.request.arguments.keys():
-                if self.get_argument(name) == uri and name.startswith(prefix):
-                    part = name[len(prefix):]
-                    ax_name = "openid." + ax_ns + ".value." + part
-                    break
-            if not ax_name:
-                return u""
-            return self.get_argument(ax_name, u"")
-
-        email = get_ax_arg("http://axschema.org/contact/email")
-        name = get_ax_arg("http://axschema.org/namePerson")
-        first_name = get_ax_arg("http://axschema.org/namePerson/first")
-        last_name = get_ax_arg("http://axschema.org/namePerson/last")
-        username = get_ax_arg("http://axschema.org/namePerson/friendly")
-        locale = get_ax_arg("http://axschema.org/pref/language").lower()
-        user = dict()
-        name_parts = []
-        if first_name:
-            user["first_name"] = first_name
-            name_parts.append(first_name)
-        if last_name:
-            user["last_name"] = last_name
-            name_parts.append(last_name)
-        if name:
-            user["name"] = name
-        elif name_parts:
-            user["name"] = u" ".join(name_parts)
-        elif email:
-            user["name"] = email.split("@")[0]
-        if email:
-            user["email"] = email
-        if locale:
-            user["locale"] = locale
-        if username:
-            user["username"] = username
-        claimed_id = self.get_argument("openid.claimed_id", None)
-        if claimed_id:
-            user["claimed_id"] = claimed_id
-        future.set_result(user)
-
-    def get_auth_http_client(self):
-        """Returns the `.AsyncHTTPClient` instance to be used for auth requests.
-
-        May be overridden by subclasses to use an HTTP client other than
-        the default.
-        """
-        return httpclient.AsyncHTTPClient()
-
-
-class OAuthMixin(object):
-    """Abstract implementation of OAuth 1.0 and 1.0a.
-
-    See `TwitterMixin` below for an example implementation.
-
-    Class attributes:
-
-    * ``_OAUTH_AUTHORIZE_URL``: The service's OAuth authorization url.
-    * ``_OAUTH_ACCESS_TOKEN_URL``: The service's OAuth access token url.
-    * ``_OAUTH_VERSION``: May be either "1.0" or "1.0a".
-    * ``_OAUTH_NO_CALLBACKS``: Set this to True if the service requires
-      advance registration of callbacks.
-
-    Subclasses must also override the `_oauth_get_user_future` and
-    `_oauth_consumer_token` methods.
-    """
-    @return_future
-    def authorize_redirect(self, callback_uri=None, extra_params=None,
-                           http_client=None, callback=None):
-        """Redirects the user to obtain OAuth authorization for this service.
-
-        The ``callback_uri`` may be omitted if you have previously
-        registered a callback URI with the third-party service.  For
-        some services (including Friendfeed), you must use a
-        previously-registered callback URI and cannot specify a
-        callback via this method.
-
-        This method sets a cookie called ``_oauth_request_token`` which is
-        subsequently used (and cleared) in `get_authenticated_user` for
-        security purposes.
-
-        Note that this method is asynchronous, although it calls
-        `.RequestHandler.finish` for you so it may not be necessary
-        to pass a callback or use the `.Future` it returns.  However,
-        if this method is called from a function decorated with
-        `.gen.coroutine`, you must call it with ``yield`` to keep the
-        response from being closed prematurely.
-
-        .. versionchanged:: 3.1
-           Now returns a `.Future` and takes an optional callback, for
-           compatibility with `.gen.coroutine`.
-        """
-        if callback_uri and getattr(self, "_OAUTH_NO_CALLBACKS", False):
-            raise Exception("This service does not support oauth_callback")
-        if http_client is None:
-            http_client = self.get_auth_http_client()
-        if getattr(self, "_OAUTH_VERSION", "1.0a") == "1.0a":
-            http_client.fetch(
-                self._oauth_request_token_url(callback_uri=callback_uri,
-                                              extra_params=extra_params),
-                functools.partial(
-                    self._on_request_token,
-                    self._OAUTH_AUTHORIZE_URL,
-                    callback_uri,
-                    callback))
-        else:
-            http_client.fetch(
-                self._oauth_request_token_url(),
-                functools.partial(
-                    self._on_request_token, self._OAUTH_AUTHORIZE_URL,
-                    callback_uri,
-                    callback))
-
-    @_auth_return_future
-    def get_authenticated_user(self, callback, http_client=None):
-        """Gets the OAuth authorized user and access token.
-
-        This method should be called from the handler for your
-        OAuth callback URL to complete the registration process. We run the
-        callback with the authenticated user dictionary.  This dictionary
-        will contain an ``access_key`` which can be used to make authorized
-        requests to this service on behalf of the user.  The dictionary will
-        also contain other fields such as ``name``, depending on the service
-        used.
-        """
-        future = callback
-        request_key = escape.utf8(self.get_argument("oauth_token"))
-        oauth_verifier = self.get_argument("oauth_verifier", None)
-        request_cookie = self.get_cookie("_oauth_request_token")
-        if not request_cookie:
-            future.set_exception(AuthError(
-                "Missing OAuth request token cookie"))
-            return
-        self.clear_cookie("_oauth_request_token")
-        cookie_key, cookie_secret = [base64.b64decode(escape.utf8(i)) for i in request_cookie.split("|")]
-        if cookie_key != request_key:
-            future.set_exception(AuthError(
-                "Request token does not match cookie"))
-            return
-        token = dict(key=cookie_key, secret=cookie_secret)
-        if oauth_verifier:
-            token["verifier"] = oauth_verifier
-        if http_client is None:
-            http_client = self.get_auth_http_client()
-        http_client.fetch(self._oauth_access_token_url(token),
-                          functools.partial(self._on_access_token, callback))
-
-    def _oauth_request_token_url(self, callback_uri=None, extra_params=None):
-        consumer_token = self._oauth_consumer_token()
-        url = self._OAUTH_REQUEST_TOKEN_URL
-        args = dict(
-            oauth_consumer_key=escape.to_basestring(consumer_token["key"]),
-            oauth_signature_method="HMAC-SHA1",
-            oauth_timestamp=str(int(time.time())),
-            oauth_nonce=escape.to_basestring(binascii.b2a_hex(uuid.uuid4().bytes)),
-            oauth_version="1.0",
-        )
-        if getattr(self, "_OAUTH_VERSION", "1.0a") == "1.0a":
-            if callback_uri == "oob":
-                args["oauth_callback"] = "oob"
-            elif callback_uri:
-                args["oauth_callback"] = urlparse.urljoin(
-                    self.request.full_url(), callback_uri)
-            if extra_params:
-                args.update(extra_params)
-            signature = _oauth10a_signature(consumer_token, "GET", url, args)
-        else:
-            signature = _oauth_signature(consumer_token, "GET", url, args)
-
-        args["oauth_signature"] = signature
-        return url + "?" + urllib_parse.urlencode(args)
-
-    def _on_request_token(self, authorize_url, callback_uri, callback,
-                          response):
-        if response.error:
-            raise Exception("Could not get request token: %s" % response.error)
-        request_token = _oauth_parse_response(response.body)
-        data = (base64.b64encode(escape.utf8(request_token["key"])) + b"|" +
-                base64.b64encode(escape.utf8(request_token["secret"])))
-        self.set_cookie("_oauth_request_token", data)
-        args = dict(oauth_token=request_token["key"])
-        if callback_uri == "oob":
-            self.finish(authorize_url + "?" + urllib_parse.urlencode(args))
-            callback()
-            return
-        elif callback_uri:
-            args["oauth_callback"] = urlparse.urljoin(
-                self.request.full_url(), callback_uri)
-        self.redirect(authorize_url + "?" + urllib_parse.urlencode(args))
-        callback()
-
-    def _oauth_access_token_url(self, request_token):
-        consumer_token = self._oauth_consumer_token()
-        url = self._OAUTH_ACCESS_TOKEN_URL
-        args = dict(
-            oauth_consumer_key=escape.to_basestring(consumer_token["key"]),
-            oauth_token=escape.to_basestring(request_token["key"]),
-            oauth_signature_method="HMAC-SHA1",
-            oauth_timestamp=str(int(time.time())),
-            oauth_nonce=escape.to_basestring(binascii.b2a_hex(uuid.uuid4().bytes)),
-            oauth_version="1.0",
-        )
-        if "verifier" in request_token:
-            args["oauth_verifier"] = request_token["verifier"]
-
-        if getattr(self, "_OAUTH_VERSION", "1.0a") == "1.0a":
-            signature = _oauth10a_signature(consumer_token, "GET", url, args,
-                                            request_token)
-        else:
-            signature = _oauth_signature(consumer_token, "GET", url, args,
-                                         request_token)
-
-        args["oauth_signature"] = signature
-        return url + "?" + urllib_parse.urlencode(args)
-
-    def _on_access_token(self, future, response):
-        if response.error:
-            future.set_exception(AuthError("Could not fetch access token"))
-            return
-
-        access_token = _oauth_parse_response(response.body)
-        self._oauth_get_user_future(access_token).add_done_callback(
-            functools.partial(self._on_oauth_get_user, access_token, future))
-
-    def _oauth_consumer_token(self):
-        """Subclasses must override this to return their OAuth consumer keys.
-
-        The return value should be a `dict` with keys ``key`` and ``secret``.
-        """
-        raise NotImplementedError()
-
-    @return_future
-    def _oauth_get_user_future(self, access_token, callback):
-        """Subclasses must override this to get basic information about the
-        user.
-
-        Should return a `.Future` whose result is a dictionary
-        containing information about the user, which may have been
-        retrieved by using ``access_token`` to make a request to the
-        service.
-
-        The access token will be added to the returned dictionary to make
-        the result of `get_authenticated_user`.
-
-        For backwards compatibility, the callback-based ``_oauth_get_user``
-        method is also supported.
-        """
-        # By default, call the old-style _oauth_get_user, but new code
-        # should override this method instead.
-        self._oauth_get_user(access_token, callback)
-
-    def _oauth_get_user(self, access_token, callback):
-        raise NotImplementedError()
-
-    def _on_oauth_get_user(self, access_token, future, user_future):
-        if user_future.exception() is not None:
-            future.set_exception(user_future.exception())
-            return
-        user = user_future.result()
-        if not user:
-            future.set_exception(AuthError("Error getting user"))
-            return
-        user["access_token"] = access_token
-        future.set_result(user)
-
-    def _oauth_request_parameters(self, url, access_token, parameters={},
-                                  method="GET"):
-        """Returns the OAuth parameters as a dict for the given request.
-
-        parameters should include all POST arguments and query string arguments
-        that will be sent with the request.
-        """
-        consumer_token = self._oauth_consumer_token()
-        base_args = dict(
-            oauth_consumer_key=escape.to_basestring(consumer_token["key"]),
-            oauth_token=escape.to_basestring(access_token["key"]),
-            oauth_signature_method="HMAC-SHA1",
-            oauth_timestamp=str(int(time.time())),
-            oauth_nonce=escape.to_basestring(binascii.b2a_hex(uuid.uuid4().bytes)),
-            oauth_version="1.0",
-        )
-        args = {}
-        args.update(base_args)
-        args.update(parameters)
-        if getattr(self, "_OAUTH_VERSION", "1.0a") == "1.0a":
-            signature = _oauth10a_signature(consumer_token, method, url, args,
-                                            access_token)
-        else:
-            signature = _oauth_signature(consumer_token, method, url, args,
-                                         access_token)
-        base_args["oauth_signature"] = escape.to_basestring(signature)
-        return base_args
-
-    def get_auth_http_client(self):
-        """Returns the `.AsyncHTTPClient` instance to be used for auth requests.
-
-        May be overridden by subclasses to use an HTTP client other than
-        the default.
-        """
-        return httpclient.AsyncHTTPClient()
-
-
-class OAuth2Mixin(object):
-    """Abstract implementation of OAuth 2.0.
-
-    See `FacebookGraphMixin` or `GoogleOAuth2Mixin` below for example
-    implementations.
-
-    Class attributes:
-
-    * ``_OAUTH_AUTHORIZE_URL``: The service's authorization url.
-    * ``_OAUTH_ACCESS_TOKEN_URL``:  The service's access token url.
-    """
-    @return_future
-    def authorize_redirect(self, redirect_uri=None, client_id=None,
-                           client_secret=None, extra_params=None,
-                           callback=None, scope=None, response_type="code"):
-        """Redirects the user to obtain OAuth authorization for this service.
-
-        Some providers require that you register a redirect URL with
-        your application instead of passing one via this method. You
-        should call this method to log the user in, and then call
-        ``get_authenticated_user`` in the handler for your
-        redirect URL to complete the authorization process.
-
-        .. versionchanged:: 3.1
-           Returns a `.Future` and takes an optional callback.  These are
-           not strictly necessary as this method is synchronous,
-           but they are supplied for consistency with
-           `OAuthMixin.authorize_redirect`.
-        """
-        args = {
-            "redirect_uri": redirect_uri,
-            "client_id": client_id,
-            "response_type": response_type
-        }
-        if extra_params:
-            args.update(extra_params)
-        if scope:
-            args['scope'] = ' '.join(scope)
-        self.redirect(
-            url_concat(self._OAUTH_AUTHORIZE_URL, args))
-        callback()
-
-    def _oauth_request_token_url(self, redirect_uri=None, client_id=None,
-                                 client_secret=None, code=None,
-                                 extra_params=None):
-        url = self._OAUTH_ACCESS_TOKEN_URL
-        args = dict(
-            redirect_uri=redirect_uri,
-            code=code,
-            client_id=client_id,
-            client_secret=client_secret,
-        )
-        if extra_params:
-            args.update(extra_params)
-        return url_concat(url, args)
-
-    @_auth_return_future
-    def oauth2_request(self, url, callback, access_token=None,
-                       post_args=None, **args):
-        """Fetches the given URL auth an OAuth2 access token.
-
-        If the request is a POST, ``post_args`` should be provided. Query
-        string arguments should be given as keyword arguments.
-
-        Example usage:
-
-        ..testcode::
-
-            class MainHandler(tornado.web.RequestHandler,
-                              tornado.auth.FacebookGraphMixin):
-                @tornado.web.authenticated
-                @tornado.gen.coroutine
-                def get(self):
-                    new_entry = yield self.oauth2_request(
-                        "https://graph.facebook.com/me/feed",
-                        post_args={"message": "I am posting from my Tornado application!"},
-                        access_token=self.current_user["access_token"])
-
-                    if not new_entry:
-                        # Call failed; perhaps missing permission?
-                        yield self.authorize_redirect()
-                        return
-                    self.finish("Posted a message!")
-
-        .. testoutput::
-           :hide:
-
-        .. versionadded:: 4.3
-        """
-        all_args = {}
-        if access_token:
-            all_args["access_token"] = access_token
-            all_args.update(args)
-
-        if all_args:
-            url += "?" + urllib_parse.urlencode(all_args)
-        callback = functools.partial(self._on_oauth2_request, callback)
-        http = self.get_auth_http_client()
-        if post_args is not None:
-            http.fetch(url, method="POST", body=urllib_parse.urlencode(post_args),
-                       callback=callback)
-        else:
-            http.fetch(url, callback=callback)
-
-    def _on_oauth2_request(self, future, response):
-        if response.error:
-            future.set_exception(AuthError("Error response %s fetching %s" %
-                                           (response.error, response.request.url)))
-            return
-
-        future.set_result(escape.json_decode(response.body))
-
-    def get_auth_http_client(self):
-        """Returns the `.AsyncHTTPClient` instance to be used for auth requests.
-
-        May be overridden by subclasses to use an HTTP client other than
-        the default.
-
-        .. versionadded:: 4.3
-        """
-        return httpclient.AsyncHTTPClient()
-
-
-class TwitterMixin(OAuthMixin):
-    """Twitter OAuth authentication.
-
-    To authenticate with Twitter, register your application with
-    Twitter at http://twitter.com/apps. Then copy your Consumer Key
-    and Consumer Secret to the application
-    `~tornado.web.Application.settings` ``twitter_consumer_key`` and
-    ``twitter_consumer_secret``. Use this mixin on the handler for the
-    URL you registered as your application's callback URL.
-
-    When your application is set up, you can use this mixin like this
-    to authenticate the user with Twitter and get access to their stream:
-
-    .. testcode::
-
-        class TwitterLoginHandler(tornado.web.RequestHandler,
-                                  tornado.auth.TwitterMixin):
-            @tornado.gen.coroutine
-            def get(self):
-                if self.get_argument("oauth_token", None):
-                    user = yield self.get_authenticated_user()
-                    # Save the user using e.g. set_secure_cookie()
-                else:
-                    yield self.authorize_redirect()
-
-    .. testoutput::
-       :hide:
-
-    The user object returned by `~OAuthMixin.get_authenticated_user`
-    includes the attributes ``username``, ``name``, ``access_token``,
-    and all of the custom Twitter user attributes described at
-    https://dev.twitter.com/docs/api/1.1/get/users/show
-    """
-    _OAUTH_REQUEST_TOKEN_URL = "https://api.twitter.com/oauth/request_token"
-    _OAUTH_ACCESS_TOKEN_URL = "https://api.twitter.com/oauth/access_token"
-    _OAUTH_AUTHORIZE_URL = "https://api.twitter.com/oauth/authorize"
-    _OAUTH_AUTHENTICATE_URL = "https://api.twitter.com/oauth/authenticate"
-    _OAUTH_NO_CALLBACKS = False
-    _TWITTER_BASE_URL = "https://api.twitter.com/1.1"
-
-    @return_future
-    def authenticate_redirect(self, callback_uri=None, callback=None):
-        """Just like `~OAuthMixin.authorize_redirect`, but
-        auto-redirects if authorized.
-
-        This is generally the right interface to use if you are using
-        Twitter for single-sign on.
-
-        .. versionchanged:: 3.1
-           Now returns a `.Future` and takes an optional callback, for
-           compatibility with `.gen.coroutine`.
-        """
-        http = self.get_auth_http_client()
-        http.fetch(self._oauth_request_token_url(callback_uri=callback_uri),
-                   functools.partial(
-                       self._on_request_token, self._OAUTH_AUTHENTICATE_URL,
-                       None, callback))
-
-    @_auth_return_future
-    def twitter_request(self, path, callback=None, access_token=None,
-                        post_args=None, **args):
-        """Fetches the given API path, e.g., ``statuses/user_timeline/btaylor``
-
-        The path should not include the format or API version number.
-        (we automatically use JSON format and API version 1).
-
-        If the request is a POST, ``post_args`` should be provided. Query
-        string arguments should be given as keyword arguments.
-
-        All the Twitter methods are documented at http://dev.twitter.com/
-
-        Many methods require an OAuth access token which you can
-        obtain through `~OAuthMixin.authorize_redirect` and
-        `~OAuthMixin.get_authenticated_user`. The user returned through that
-        process includes an 'access_token' attribute that can be used
-        to make authenticated requests via this method. Example
-        usage:
-
-        .. testcode::
-
-            class MainHandler(tornado.web.RequestHandler,
-                              tornado.auth.TwitterMixin):
-                @tornado.web.authenticated
-                @tornado.gen.coroutine
-                def get(self):
-                    new_entry = yield self.twitter_request(
-                        "/statuses/update",
-                        post_args={"status": "Testing Tornado Web Server"},
-                        access_token=self.current_user["access_token"])
-                    if not new_entry:
-                        # Call failed; perhaps missing permission?
-                        yield self.authorize_redirect()
-                        return
-                    self.finish("Posted a message!")
-
-        .. testoutput::
-           :hide:
-
-        """
-        if path.startswith('http:') or path.startswith('https:'):
-            # Raw urls are useful for e.g. search which doesn't follow the
-            # usual pattern: http://search.twitter.com/search.json
-            url = path
-        else:
-            url = self._TWITTER_BASE_URL + path + ".json"
-        # Add the OAuth resource request signature if we have credentials
-        if access_token:
-            all_args = {}
-            all_args.update(args)
-            all_args.update(post_args or {})
-            method = "POST" if post_args is not None else "GET"
-            oauth = self._oauth_request_parameters(
-                url, access_token, all_args, method=method)
-            args.update(oauth)
-        if args:
-            url += "?" + urllib_parse.urlencode(args)
-        http = self.get_auth_http_client()
-        http_callback = functools.partial(self._on_twitter_request, callback)
-        if post_args is not None:
-            http.fetch(url, method="POST", body=urllib_parse.urlencode(post_args),
-                       callback=http_callback)
-        else:
-            http.fetch(url, callback=http_callback)
-
-    def _on_twitter_request(self, future, response):
-        if response.error:
-            future.set_exception(AuthError(
-                "Error response %s fetching %s" % (response.error,
-                                                   response.request.url)))
-            return
-        future.set_result(escape.json_decode(response.body))
-
-    def _oauth_consumer_token(self):
-        self.require_setting("twitter_consumer_key", "Twitter OAuth")
-        self.require_setting("twitter_consumer_secret", "Twitter OAuth")
-        return dict(
-            key=self.settings["twitter_consumer_key"],
-            secret=self.settings["twitter_consumer_secret"])
-
-    @gen.coroutine
-    def _oauth_get_user_future(self, access_token):
-        user = yield self.twitter_request(
-            "/account/verify_credentials",
-            access_token=access_token)
-        if user:
-            user["username"] = user["screen_name"]
-        raise gen.Return(user)
-
-
-class GoogleOAuth2Mixin(OAuth2Mixin):
-    """Google authentication using OAuth2.
-
-    In order to use, register your application with Google and copy the
-    relevant parameters to your application settings.
-
-    * Go to the Google Dev Console at http://console.developers.google.com
-    * Select a project, or create a new one.
-    * In the sidebar on the left, select APIs & Auth.
-    * In the list of APIs, find the Google+ API service and set it to ON.
-    * In the sidebar on the left, select Credentials.
-    * In the OAuth section of the page, select Create New Client ID.
-    * Set the Redirect URI to point to your auth handler
-    * Copy the "Client secret" and "Client ID" to the application settings as
-      {"google_oauth": {"key": CLIENT_ID, "secret": CLIENT_SECRET}}
-
-    .. versionadded:: 3.2
-    """
-    _OAUTH_AUTHORIZE_URL = "https://accounts.google.com/o/oauth2/auth"
-    _OAUTH_ACCESS_TOKEN_URL = "https://accounts.google.com/o/oauth2/token"
-    _OAUTH_USERINFO_URL = "https://www.googleapis.com/oauth2/v1/userinfo"
-    _OAUTH_NO_CALLBACKS = False
-    _OAUTH_SETTINGS_KEY = 'google_oauth'
-
-    @_auth_return_future
-    def get_authenticated_user(self, redirect_uri, code, callback):
-        """Handles the login for the Google user, returning an access token.
-
-        The result is a dictionary containing an ``access_token`` field
-        ([among others](https://developers.google.com/identity/protocols/OAuth2WebServer#handlingtheresponse)).
-        Unlike other ``get_authenticated_user`` methods in this package,
-        this method does not return any additional information about the user.
-        The returned access token can be used with `OAuth2Mixin.oauth2_request`
-        to request additional information (perhaps from
-        ``https://www.googleapis.com/oauth2/v2/userinfo``)
-
-        Example usage:
-
-        .. testcode::
-
-            class GoogleOAuth2LoginHandler(tornado.web.RequestHandler,
-                                           tornado.auth.GoogleOAuth2Mixin):
-                @tornado.gen.coroutine
-                def get(self):
-                    if self.get_argument('code', False):
-                        access = yield self.get_authenticated_user(
-                            redirect_uri='http://your.site.com/auth/google',
-                            code=self.get_argument('code'))
-                        user = yield self.oauth2_request(
-                            "https://www.googleapis.com/oauth2/v1/userinfo",
-                            access_token=access["access_token"])
-                        # Save the user and access token with
-                        # e.g. set_secure_cookie.
-                    else:
-                        yield self.authorize_redirect(
-                            redirect_uri='http://your.site.com/auth/google',
-                            client_id=self.settings['google_oauth']['key'],
-                            scope=['profile', 'email'],
-                            response_type='code',
-                            extra_params={'approval_prompt': 'auto'})
-
-        .. testoutput::
-           :hide:
-
-        """
-        http = self.get_auth_http_client()
-        body = urllib_parse.urlencode({
-            "redirect_uri": redirect_uri,
-            "code": code,
-            "client_id": self.settings[self._OAUTH_SETTINGS_KEY]['key'],
-            "client_secret": self.settings[self._OAUTH_SETTINGS_KEY]['secret'],
-            "grant_type": "authorization_code",
-        })
-
-        http.fetch(self._OAUTH_ACCESS_TOKEN_URL,
-                   functools.partial(self._on_access_token, callback),
-                   method="POST", headers={'Content-Type': 'application/x-www-form-urlencoded'}, body=body)
-
-    def _on_access_token(self, future, response):
-        """Callback function for the exchange to the access token."""
-        if response.error:
-            future.set_exception(AuthError('Google auth error: %s' % str(response)))
-            return
-
-        args = escape.json_decode(response.body)
-        future.set_result(args)
-
-
-class FacebookGraphMixin(OAuth2Mixin):
-    """Facebook authentication using the new Graph API and OAuth2."""
-    _OAUTH_ACCESS_TOKEN_URL = "https://graph.facebook.com/oauth/access_token?"
-    _OAUTH_AUTHORIZE_URL = "https://www.facebook.com/dialog/oauth?"
-    _OAUTH_NO_CALLBACKS = False
-    _FACEBOOK_BASE_URL = "https://graph.facebook.com"
-
-    @_auth_return_future
-    def get_authenticated_user(self, redirect_uri, client_id, client_secret,
-                               code, callback, extra_fields=None):
-        """Handles the login for the Facebook user, returning a user object.
-
-        Example usage:
-
-        .. testcode::
-
-            class FacebookGraphLoginHandler(tornado.web.RequestHandler,
-                                            tornado.auth.FacebookGraphMixin):
-              @tornado.gen.coroutine
-              def get(self):
-                  if self.get_argument("code", False):
-                      user = yield self.get_authenticated_user(
-                          redirect_uri='/auth/facebookgraph/',
-                          client_id=self.settings["facebook_api_key"],
-                          client_secret=self.settings["facebook_secret"],
-                          code=self.get_argument("code"))
-                      # Save the user with e.g. set_secure_cookie
-                  else:
-                      yield self.authorize_redirect(
-                          redirect_uri='/auth/facebookgraph/',
-                          client_id=self.settings["facebook_api_key"],
-                          extra_params={"scope": "read_stream,offline_access"})
-
-        .. testoutput::
-           :hide:
-
-        This method returns a dictionary which may contain the following fields:
-
-        * ``access_token``, a string which may be passed to `facebook_request`
-        * ``session_expires``, an integer encoded as a string representing
-          the time until the access token expires in seconds. This field should
-          be used like ``int(user['session_expires'])``; in a future version of
-          Tornado it will change from a string to an integer.
-        * ``id``, ``name``, ``first_name``, ``last_name``, ``locale``, ``picture``,
-          ``link``, plus any fields named in the ``extra_fields`` argument. These
-          fields are copied from the Facebook graph API `user object <https://developers.facebook.com/docs/graph-api/reference/user>`_
-
-        .. versionchanged:: 4.5
-           The ``session_expires`` field was updated to support changes made to the
-           Facebook API in March 2017.
-        """
-        http = self.get_auth_http_client()
-        args = {
-            "redirect_uri": redirect_uri,
-            "code": code,
-            "client_id": client_id,
-            "client_secret": client_secret,
-        }
-
-        fields = set(['id', 'name', 'first_name', 'last_name',
-                      'locale', 'picture', 'link'])
-        if extra_fields:
-            fields.update(extra_fields)
-
-        http.fetch(self._oauth_request_token_url(**args),
-                   functools.partial(self._on_access_token, redirect_uri, client_id,
-                                     client_secret, callback, fields))
-
-    def _on_access_token(self, redirect_uri, client_id, client_secret,
-                         future, fields, response):
-        if response.error:
-            future.set_exception(AuthError('Facebook auth error: %s' % str(response)))
-            return
-
-        args = escape.json_decode(response.body)
-        session = {
-            "access_token": args.get("access_token"),
-            "expires_in": args.get("expires_in")
-        }
-
-        self.facebook_request(
-            path="/me",
-            callback=functools.partial(
-                self._on_get_user_info, future, session, fields),
-            access_token=session["access_token"],
-            appsecret_proof=hmac.new(key=client_secret.encode('utf8'),
-                                     msg=session["access_token"].encode('utf8'),
-                                     digestmod=hashlib.sha256).hexdigest(),
-            fields=",".join(fields)
-        )
-
-    def _on_get_user_info(self, future, session, fields, user):
-        if user is None:
-            future.set_result(None)
-            return
-
-        fieldmap = {}
-        for field in fields:
-            fieldmap[field] = user.get(field)
-
-        # session_expires is converted to str for compatibility with
-        # older versions in which the server used url-encoding and
-        # this code simply returned the string verbatim.
-        # This should change in Tornado 5.0.
-        fieldmap.update({"access_token": session["access_token"],
-                         "session_expires": str(session.get("expires_in"))})
-        future.set_result(fieldmap)
-
-    @_auth_return_future
-    def facebook_request(self, path, callback, access_token=None,
-                         post_args=None, **args):
-        """Fetches the given relative API path, e.g., "/btaylor/picture"
-
-        If the request is a POST, ``post_args`` should be provided. Query
-        string arguments should be given as keyword arguments.
-
-        An introduction to the Facebook Graph API can be found at
-        http://developers.facebook.com/docs/api
-
-        Many methods require an OAuth access token which you can
-        obtain through `~OAuth2Mixin.authorize_redirect` and
-        `get_authenticated_user`. The user returned through that
-        process includes an ``access_token`` attribute that can be
-        used to make authenticated requests via this method.
-
-        Example usage:
-
-        ..testcode::
-
-            class MainHandler(tornado.web.RequestHandler,
-                              tornado.auth.FacebookGraphMixin):
-                @tornado.web.authenticated
-                @tornado.gen.coroutine
-                def get(self):
-                    new_entry = yield self.facebook_request(
-                        "/me/feed",
-                        post_args={"message": "I am posting from my Tornado application!"},
-                        access_token=self.current_user["access_token"])
-
-                    if not new_entry:
-                        # Call failed; perhaps missing permission?
-                        yield self.authorize_redirect()
-                        return
-                    self.finish("Posted a message!")
-
-        .. testoutput::
-           :hide:
-
-        The given path is relative to ``self._FACEBOOK_BASE_URL``,
-        by default "https://graph.facebook.com".
-
-        This method is a wrapper around `OAuth2Mixin.oauth2_request`;
-        the only difference is that this method takes a relative path,
-        while ``oauth2_request`` takes a complete url.
-
-        .. versionchanged:: 3.1
-           Added the ability to override ``self._FACEBOOK_BASE_URL``.
-        """
-        url = self._FACEBOOK_BASE_URL + path
-        # Thanks to the _auth_return_future decorator, our "callback"
-        # argument is a Future, which we cannot pass as a callback to
-        # oauth2_request. Instead, have oauth2_request return a
-        # future and chain them together.
-        oauth_future = self.oauth2_request(url, access_token=access_token,
-                                           post_args=post_args, **args)
-        chain_future(oauth_future, callback)
-
-
-def _oauth_signature(consumer_token, method, url, parameters={}, token=None):
-    """Calculates the HMAC-SHA1 OAuth signature for the given request.
-
-    See http://oauth.net/core/1.0/#signing_process
-    """
-    parts = urlparse.urlparse(url)
-    scheme, netloc, path = parts[:3]
-    normalized_url = scheme.lower() + "://" + netloc.lower() + path
-
-    base_elems = []
-    base_elems.append(method.upper())
-    base_elems.append(normalized_url)
-    base_elems.append("&".join("%s=%s" % (k, _oauth_escape(str(v)))
-                               for k, v in sorted(parameters.items())))
-    base_string = "&".join(_oauth_escape(e) for e in base_elems)
-
-    key_elems = [escape.utf8(consumer_token["secret"])]
-    key_elems.append(escape.utf8(token["secret"] if token else ""))
-    key = b"&".join(key_elems)
-
-    hash = hmac.new(key, escape.utf8(base_string), hashlib.sha1)
-    return binascii.b2a_base64(hash.digest())[:-1]
-
-
-def _oauth10a_signature(consumer_token, method, url, parameters={}, token=None):
-    """Calculates the HMAC-SHA1 OAuth 1.0a signature for the given request.
-
-    See http://oauth.net/core/1.0a/#signing_process
-    """
-    parts = urlparse.urlparse(url)
-    scheme, netloc, path = parts[:3]
-    normalized_url = scheme.lower() + "://" + netloc.lower() + path
-
-    base_elems = []
-    base_elems.append(method.upper())
-    base_elems.append(normalized_url)
-    base_elems.append("&".join("%s=%s" % (k, _oauth_escape(str(v)))
-                               for k, v in sorted(parameters.items())))
-
-    base_string = "&".join(_oauth_escape(e) for e in base_elems)
-    key_elems = [escape.utf8(urllib_parse.quote(consumer_token["secret"], safe='~'))]
-    key_elems.append(escape.utf8(urllib_parse.quote(token["secret"], safe='~') if token else ""))
-    key = b"&".join(key_elems)
-
-    hash = hmac.new(key, escape.utf8(base_string), hashlib.sha1)
-    return binascii.b2a_base64(hash.digest())[:-1]
-
-
-def _oauth_escape(val):
-    if isinstance(val, unicode_type):
-        val = val.encode("utf-8")
-    return urllib_parse.quote(val, safe="~")
-
-
-def _oauth_parse_response(body):
-    # I can't find an officially-defined encoding for oauth responses and
-    # have never seen anyone use non-ascii.  Leave the response in a byte
-    # string for python 2, and use utf8 on python 3.
-    body = escape.native_str(body)
-    p = urlparse.parse_qs(body, keep_blank_values=False)
-    token = dict(key=p["oauth_token"][0], secret=p["oauth_token_secret"][0])
-
-    # Add the extra parameters the Provider included to the token
-    special = ("oauth_token", "oauth_token_secret")
-    token.update((k, p[k][0]) for k in p if k not in special)
-    return token
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""This module contains implementations of various third-party 
+authentication schemes. 
+ 
+All the classes in this file are class mixins designed to be used with 
+the `tornado.web.RequestHandler` class.  They are used in two ways: 
+ 
+* On a login handler, use methods such as ``authenticate_redirect()``, 
+  ``authorize_redirect()``, and ``get_authenticated_user()`` to 
+  establish the user's identity and store authentication tokens to your 
+  database and/or cookies. 
+* In non-login handlers, use methods such as ``facebook_request()`` 
+  or ``twitter_request()`` to use the authentication tokens to make 
+  requests to the respective services. 
+ 
+They all take slightly different arguments due to the fact all these 
+services implement authentication and authorization slightly differently. 
+See the individual service classes below for complete documentation. 
+ 
+Example usage for Google OAuth: 
+ 
+.. testcode:: 
+ 
+    class GoogleOAuth2LoginHandler(tornado.web.RequestHandler, 
+                                   tornado.auth.GoogleOAuth2Mixin): 
+        @tornado.gen.coroutine 
+        def get(self): 
+            if self.get_argument('code', False): 
+                user = yield self.get_authenticated_user( 
+                    redirect_uri='http://your.site.com/auth/google', 
+                    code=self.get_argument('code')) 
+                # Save the user with e.g. set_secure_cookie 
+            else: 
+                yield self.authorize_redirect( 
+                    redirect_uri='http://your.site.com/auth/google', 
+                    client_id=self.settings['google_oauth']['key'], 
+                    scope=['profile', 'email'], 
+                    response_type='code', 
+                    extra_params={'approval_prompt': 'auto'}) 
+ 
+.. testoutput:: 
+   :hide: 
+ 
+ 
+.. versionchanged:: 4.0 
+   All of the callback interfaces in this module are now guaranteed 
+   to run their callback with an argument of ``None`` on error. 
+   Previously some functions would do this while others would simply 
+   terminate the request on their own.  This change also ensures that 
+   errors are more consistently reported through the ``Future`` interfaces. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import base64 
+import binascii 
+import functools 
+import hashlib 
+import hmac 
+import time 
+import uuid 
+ 
+from tornado.concurrent import TracebackFuture, return_future, chain_future 
+from tornado import gen 
+from tornado import httpclient 
+from tornado import escape 
+from tornado.httputil import url_concat 
+from tornado.log import gen_log 
+from tornado.stack_context import ExceptionStackContext 
+from tornado.util import unicode_type, ArgReplacer, PY3 
+ 
+if PY3: 
+    import urllib.parse as urlparse 
+    import urllib.parse as urllib_parse 
+    long = int 
+else: 
+    import urlparse 
+    import urllib as urllib_parse 
+ 
+ 
+class AuthError(Exception): 
+    pass 
+ 
+ 
+def _auth_future_to_callback(callback, future): 
+    try: 
+        result = future.result() 
+    except AuthError as e: 
+        gen_log.warning(str(e)) 
+        result = None 
+    callback(result) 
+ 
+ 
+def _auth_return_future(f): 
+    """Similar to tornado.concurrent.return_future, but uses the auth 
+    module's legacy callback interface. 
+ 
+    Note that when using this decorator the ``callback`` parameter 
+    inside the function will actually be a future. 
+    """ 
+    replacer = ArgReplacer(f, 'callback') 
+ 
+    @functools.wraps(f) 
+    def wrapper(*args, **kwargs): 
+        future = TracebackFuture() 
+        callback, args, kwargs = replacer.replace(future, args, kwargs) 
+        if callback is not None: 
+            future.add_done_callback( 
+                functools.partial(_auth_future_to_callback, callback)) 
+ 
+        def handle_exception(typ, value, tb): 
+            if future.done(): 
+                return False 
+            else: 
+                future.set_exc_info((typ, value, tb)) 
+                return True 
+        with ExceptionStackContext(handle_exception): 
+            f(*args, **kwargs) 
+        return future 
+    return wrapper 
+ 
+ 
+class OpenIdMixin(object): 
+    """Abstract implementation of OpenID and Attribute Exchange. 
+ 
+    Class attributes: 
+ 
+    * ``_OPENID_ENDPOINT``: the identity provider's URI. 
+    """ 
+    @return_future 
+    def authenticate_redirect(self, callback_uri=None, 
+                              ax_attrs=["name", "email", "language", "username"], 
+                              callback=None): 
+        """Redirects to the authentication URL for this service. 
+ 
+        After authentication, the service will redirect back to the given 
+        callback URI with additional parameters including ``openid.mode``. 
+ 
+        We request the given attributes for the authenticated user by 
+        default (name, email, language, and username). If you don't need 
+        all those attributes for your app, you can request fewer with 
+        the ax_attrs keyword argument. 
+ 
+        .. versionchanged:: 3.1 
+           Returns a `.Future` and takes an optional callback.  These are 
+           not strictly necessary as this method is synchronous, 
+           but they are supplied for consistency with 
+           `OAuthMixin.authorize_redirect`. 
+        """ 
+        callback_uri = callback_uri or self.request.uri 
+        args = self._openid_args(callback_uri, ax_attrs=ax_attrs) 
+        self.redirect(self._OPENID_ENDPOINT + "?" + urllib_parse.urlencode(args)) 
+        callback() 
+ 
+    @_auth_return_future 
+    def get_authenticated_user(self, callback, http_client=None): 
+        """Fetches the authenticated user data upon redirect. 
+ 
+        This method should be called by the handler that receives the 
+        redirect from the `authenticate_redirect()` method (which is 
+        often the same as the one that calls it; in that case you would 
+        call `get_authenticated_user` if the ``openid.mode`` parameter 
+        is present and `authenticate_redirect` if it is not). 
+ 
+        The result of this method will generally be used to set a cookie. 
+        """ 
+        # Verify the OpenID response via direct request to the OP 
+        args = dict((k, v[-1]) for k, v in self.request.arguments.items()) 
+        args["openid.mode"] = u"check_authentication" 
+        url = self._OPENID_ENDPOINT 
+        if http_client is None: 
+            http_client = self.get_auth_http_client() 
+        http_client.fetch(url, functools.partial( 
+            self._on_authentication_verified, callback), 
+            method="POST", body=urllib_parse.urlencode(args)) 
+ 
+    def _openid_args(self, callback_uri, ax_attrs=[], oauth_scope=None): 
+        url = urlparse.urljoin(self.request.full_url(), callback_uri) 
+        args = { 
+            "openid.ns": "http://specs.openid.net/auth/2.0", 
+            "openid.claimed_id": 
+            "http://specs.openid.net/auth/2.0/identifier_select", 
+            "openid.identity": 
+            "http://specs.openid.net/auth/2.0/identifier_select", 
+            "openid.return_to": url, 
+            "openid.realm": urlparse.urljoin(url, '/'), 
+            "openid.mode": "checkid_setup", 
+        } 
+        if ax_attrs: 
+            args.update({ 
+                "openid.ns.ax": "http://openid.net/srv/ax/1.0", 
+                "openid.ax.mode": "fetch_request", 
+            }) 
+            ax_attrs = set(ax_attrs) 
+            required = [] 
+            if "name" in ax_attrs: 
+                ax_attrs -= set(["name", "firstname", "fullname", "lastname"]) 
+                required += ["firstname", "fullname", "lastname"] 
+                args.update({ 
+                    "openid.ax.type.firstname": 
+                    "http://axschema.org/namePerson/first", 
+                    "openid.ax.type.fullname": 
+                    "http://axschema.org/namePerson", 
+                    "openid.ax.type.lastname": 
+                    "http://axschema.org/namePerson/last", 
+                }) 
+            known_attrs = { 
+                "email": "http://axschema.org/contact/email", 
+                "language": "http://axschema.org/pref/language", 
+                "username": "http://axschema.org/namePerson/friendly", 
+            } 
+            for name in ax_attrs: 
+                args["openid.ax.type." + name] = known_attrs[name] 
+                required.append(name) 
+            args["openid.ax.required"] = ",".join(required) 
+        if oauth_scope: 
+            args.update({ 
+                "openid.ns.oauth": 
+                "http://specs.openid.net/extensions/oauth/1.0", 
+                "openid.oauth.consumer": self.request.host.split(":")[0], 
+                "openid.oauth.scope": oauth_scope, 
+            }) 
+        return args 
+ 
+    def _on_authentication_verified(self, future, response): 
+        if response.error or b"is_valid:true" not in response.body: 
+            future.set_exception(AuthError( 
+                "Invalid OpenID response: %s" % (response.error or 
+                                                 response.body))) 
+            return 
+ 
+        # Make sure we got back at least an email from attribute exchange 
+        ax_ns = None 
+        for name in self.request.arguments: 
+            if name.startswith("openid.ns.") and \ 
+                    self.get_argument(name) == u"http://openid.net/srv/ax/1.0": 
+                ax_ns = name[10:] 
+                break 
+ 
+        def get_ax_arg(uri): 
+            if not ax_ns: 
+                return u"" 
+            prefix = "openid." + ax_ns + ".type." 
+            ax_name = None 
+            for name in self.request.arguments.keys(): 
+                if self.get_argument(name) == uri and name.startswith(prefix): 
+                    part = name[len(prefix):] 
+                    ax_name = "openid." + ax_ns + ".value." + part 
+                    break 
+            if not ax_name: 
+                return u"" 
+            return self.get_argument(ax_name, u"") 
+ 
+        email = get_ax_arg("http://axschema.org/contact/email") 
+        name = get_ax_arg("http://axschema.org/namePerson") 
+        first_name = get_ax_arg("http://axschema.org/namePerson/first") 
+        last_name = get_ax_arg("http://axschema.org/namePerson/last") 
+        username = get_ax_arg("http://axschema.org/namePerson/friendly") 
+        locale = get_ax_arg("http://axschema.org/pref/language").lower() 
+        user = dict() 
+        name_parts = [] 
+        if first_name: 
+            user["first_name"] = first_name 
+            name_parts.append(first_name) 
+        if last_name: 
+            user["last_name"] = last_name 
+            name_parts.append(last_name) 
+        if name: 
+            user["name"] = name 
+        elif name_parts: 
+            user["name"] = u" ".join(name_parts) 
+        elif email: 
+            user["name"] = email.split("@")[0] 
+        if email: 
+            user["email"] = email 
+        if locale: 
+            user["locale"] = locale 
+        if username: 
+            user["username"] = username 
+        claimed_id = self.get_argument("openid.claimed_id", None) 
+        if claimed_id: 
+            user["claimed_id"] = claimed_id 
+        future.set_result(user) 
+ 
+    def get_auth_http_client(self): 
+        """Returns the `.AsyncHTTPClient` instance to be used for auth requests. 
+ 
+        May be overridden by subclasses to use an HTTP client other than 
+        the default. 
+        """ 
+        return httpclient.AsyncHTTPClient() 
+ 
+ 
+class OAuthMixin(object): 
+    """Abstract implementation of OAuth 1.0 and 1.0a. 
+ 
+    See `TwitterMixin` below for an example implementation. 
+ 
+    Class attributes: 
+ 
+    * ``_OAUTH_AUTHORIZE_URL``: The service's OAuth authorization url. 
+    * ``_OAUTH_ACCESS_TOKEN_URL``: The service's OAuth access token url. 
+    * ``_OAUTH_VERSION``: May be either "1.0" or "1.0a". 
+    * ``_OAUTH_NO_CALLBACKS``: Set this to True if the service requires 
+      advance registration of callbacks. 
+ 
+    Subclasses must also override the `_oauth_get_user_future` and 
+    `_oauth_consumer_token` methods. 
+    """ 
+    @return_future 
+    def authorize_redirect(self, callback_uri=None, extra_params=None, 
+                           http_client=None, callback=None): 
+        """Redirects the user to obtain OAuth authorization for this service. 
+ 
+        The ``callback_uri`` may be omitted if you have previously 
+        registered a callback URI with the third-party service.  For 
+        some services (including Friendfeed), you must use a 
+        previously-registered callback URI and cannot specify a 
+        callback via this method. 
+ 
+        This method sets a cookie called ``_oauth_request_token`` which is 
+        subsequently used (and cleared) in `get_authenticated_user` for 
+        security purposes. 
+ 
+        Note that this method is asynchronous, although it calls 
+        `.RequestHandler.finish` for you so it may not be necessary 
+        to pass a callback or use the `.Future` it returns.  However, 
+        if this method is called from a function decorated with 
+        `.gen.coroutine`, you must call it with ``yield`` to keep the 
+        response from being closed prematurely. 
+ 
+        .. versionchanged:: 3.1 
+           Now returns a `.Future` and takes an optional callback, for 
+           compatibility with `.gen.coroutine`. 
+        """ 
+        if callback_uri and getattr(self, "_OAUTH_NO_CALLBACKS", False): 
+            raise Exception("This service does not support oauth_callback") 
+        if http_client is None: 
+            http_client = self.get_auth_http_client() 
+        if getattr(self, "_OAUTH_VERSION", "1.0a") == "1.0a": 
+            http_client.fetch( 
+                self._oauth_request_token_url(callback_uri=callback_uri, 
+                                              extra_params=extra_params), 
+                functools.partial( 
+                    self._on_request_token, 
+                    self._OAUTH_AUTHORIZE_URL, 
+                    callback_uri, 
+                    callback)) 
+        else: 
+            http_client.fetch( 
+                self._oauth_request_token_url(), 
+                functools.partial( 
+                    self._on_request_token, self._OAUTH_AUTHORIZE_URL, 
+                    callback_uri, 
+                    callback)) 
+ 
+    @_auth_return_future 
+    def get_authenticated_user(self, callback, http_client=None): 
+        """Gets the OAuth authorized user and access token. 
+ 
+        This method should be called from the handler for your 
+        OAuth callback URL to complete the registration process. We run the 
+        callback with the authenticated user dictionary.  This dictionary 
+        will contain an ``access_key`` which can be used to make authorized 
+        requests to this service on behalf of the user.  The dictionary will 
+        also contain other fields such as ``name``, depending on the service 
+        used. 
+        """ 
+        future = callback 
+        request_key = escape.utf8(self.get_argument("oauth_token")) 
+        oauth_verifier = self.get_argument("oauth_verifier", None) 
+        request_cookie = self.get_cookie("_oauth_request_token") 
+        if not request_cookie: 
+            future.set_exception(AuthError( 
+                "Missing OAuth request token cookie")) 
+            return 
+        self.clear_cookie("_oauth_request_token") 
+        cookie_key, cookie_secret = [base64.b64decode(escape.utf8(i)) for i in request_cookie.split("|")] 
+        if cookie_key != request_key: 
+            future.set_exception(AuthError( 
+                "Request token does not match cookie")) 
+            return 
+        token = dict(key=cookie_key, secret=cookie_secret) 
+        if oauth_verifier: 
+            token["verifier"] = oauth_verifier 
+        if http_client is None: 
+            http_client = self.get_auth_http_client() 
+        http_client.fetch(self._oauth_access_token_url(token), 
+                          functools.partial(self._on_access_token, callback)) 
+ 
+    def _oauth_request_token_url(self, callback_uri=None, extra_params=None): 
+        consumer_token = self._oauth_consumer_token() 
+        url = self._OAUTH_REQUEST_TOKEN_URL 
+        args = dict( 
+            oauth_consumer_key=escape.to_basestring(consumer_token["key"]), 
+            oauth_signature_method="HMAC-SHA1", 
+            oauth_timestamp=str(int(time.time())), 
+            oauth_nonce=escape.to_basestring(binascii.b2a_hex(uuid.uuid4().bytes)), 
+            oauth_version="1.0", 
+        ) 
+        if getattr(self, "_OAUTH_VERSION", "1.0a") == "1.0a": 
+            if callback_uri == "oob": 
+                args["oauth_callback"] = "oob" 
+            elif callback_uri: 
+                args["oauth_callback"] = urlparse.urljoin( 
+                    self.request.full_url(), callback_uri) 
+            if extra_params: 
+                args.update(extra_params) 
+            signature = _oauth10a_signature(consumer_token, "GET", url, args) 
+        else: 
+            signature = _oauth_signature(consumer_token, "GET", url, args) 
+ 
+        args["oauth_signature"] = signature 
+        return url + "?" + urllib_parse.urlencode(args) 
+ 
+    def _on_request_token(self, authorize_url, callback_uri, callback, 
+                          response): 
+        if response.error: 
+            raise Exception("Could not get request token: %s" % response.error) 
+        request_token = _oauth_parse_response(response.body) 
+        data = (base64.b64encode(escape.utf8(request_token["key"])) + b"|" + 
+                base64.b64encode(escape.utf8(request_token["secret"]))) 
+        self.set_cookie("_oauth_request_token", data) 
+        args = dict(oauth_token=request_token["key"]) 
+        if callback_uri == "oob": 
+            self.finish(authorize_url + "?" + urllib_parse.urlencode(args)) 
+            callback() 
+            return 
+        elif callback_uri: 
+            args["oauth_callback"] = urlparse.urljoin( 
+                self.request.full_url(), callback_uri) 
+        self.redirect(authorize_url + "?" + urllib_parse.urlencode(args)) 
+        callback() 
+ 
+    def _oauth_access_token_url(self, request_token): 
+        consumer_token = self._oauth_consumer_token() 
+        url = self._OAUTH_ACCESS_TOKEN_URL 
+        args = dict( 
+            oauth_consumer_key=escape.to_basestring(consumer_token["key"]), 
+            oauth_token=escape.to_basestring(request_token["key"]), 
+            oauth_signature_method="HMAC-SHA1", 
+            oauth_timestamp=str(int(time.time())), 
+            oauth_nonce=escape.to_basestring(binascii.b2a_hex(uuid.uuid4().bytes)), 
+            oauth_version="1.0", 
+        ) 
+        if "verifier" in request_token: 
+            args["oauth_verifier"] = request_token["verifier"] 
+ 
+        if getattr(self, "_OAUTH_VERSION", "1.0a") == "1.0a": 
+            signature = _oauth10a_signature(consumer_token, "GET", url, args, 
+                                            request_token) 
+        else: 
+            signature = _oauth_signature(consumer_token, "GET", url, args, 
+                                         request_token) 
+ 
+        args["oauth_signature"] = signature 
+        return url + "?" + urllib_parse.urlencode(args) 
+ 
+    def _on_access_token(self, future, response): 
+        if response.error: 
+            future.set_exception(AuthError("Could not fetch access token")) 
+            return 
+ 
+        access_token = _oauth_parse_response(response.body) 
+        self._oauth_get_user_future(access_token).add_done_callback( 
+            functools.partial(self._on_oauth_get_user, access_token, future)) 
+ 
+    def _oauth_consumer_token(self): 
+        """Subclasses must override this to return their OAuth consumer keys. 
+ 
+        The return value should be a `dict` with keys ``key`` and ``secret``. 
+        """ 
+        raise NotImplementedError() 
+ 
+    @return_future 
+    def _oauth_get_user_future(self, access_token, callback): 
+        """Subclasses must override this to get basic information about the 
+        user. 
+ 
+        Should return a `.Future` whose result is a dictionary 
+        containing information about the user, which may have been 
+        retrieved by using ``access_token`` to make a request to the 
+        service. 
+ 
+        The access token will be added to the returned dictionary to make 
+        the result of `get_authenticated_user`. 
+ 
+        For backwards compatibility, the callback-based ``_oauth_get_user`` 
+        method is also supported. 
+        """ 
+        # By default, call the old-style _oauth_get_user, but new code 
+        # should override this method instead. 
+        self._oauth_get_user(access_token, callback) 
+ 
+    def _oauth_get_user(self, access_token, callback): 
+        raise NotImplementedError() 
+ 
+    def _on_oauth_get_user(self, access_token, future, user_future): 
+        if user_future.exception() is not None: 
+            future.set_exception(user_future.exception()) 
+            return 
+        user = user_future.result() 
+        if not user: 
+            future.set_exception(AuthError("Error getting user")) 
+            return 
+        user["access_token"] = access_token 
+        future.set_result(user) 
+ 
+    def _oauth_request_parameters(self, url, access_token, parameters={}, 
+                                  method="GET"): 
+        """Returns the OAuth parameters as a dict for the given request. 
+ 
+        parameters should include all POST arguments and query string arguments 
+        that will be sent with the request. 
+        """ 
+        consumer_token = self._oauth_consumer_token() 
+        base_args = dict( 
+            oauth_consumer_key=escape.to_basestring(consumer_token["key"]), 
+            oauth_token=escape.to_basestring(access_token["key"]), 
+            oauth_signature_method="HMAC-SHA1", 
+            oauth_timestamp=str(int(time.time())), 
+            oauth_nonce=escape.to_basestring(binascii.b2a_hex(uuid.uuid4().bytes)), 
+            oauth_version="1.0", 
+        ) 
+        args = {} 
+        args.update(base_args) 
+        args.update(parameters) 
+        if getattr(self, "_OAUTH_VERSION", "1.0a") == "1.0a": 
+            signature = _oauth10a_signature(consumer_token, method, url, args, 
+                                            access_token) 
+        else: 
+            signature = _oauth_signature(consumer_token, method, url, args, 
+                                         access_token) 
+        base_args["oauth_signature"] = escape.to_basestring(signature) 
+        return base_args 
+ 
+    def get_auth_http_client(self): 
+        """Returns the `.AsyncHTTPClient` instance to be used for auth requests. 
+ 
+        May be overridden by subclasses to use an HTTP client other than 
+        the default. 
+        """ 
+        return httpclient.AsyncHTTPClient() 
+ 
+ 
+class OAuth2Mixin(object): 
+    """Abstract implementation of OAuth 2.0. 
+ 
+    See `FacebookGraphMixin` or `GoogleOAuth2Mixin` below for example 
+    implementations. 
+ 
+    Class attributes: 
+ 
+    * ``_OAUTH_AUTHORIZE_URL``: The service's authorization url. 
+    * ``_OAUTH_ACCESS_TOKEN_URL``:  The service's access token url. 
+    """ 
+    @return_future 
+    def authorize_redirect(self, redirect_uri=None, client_id=None, 
+                           client_secret=None, extra_params=None, 
+                           callback=None, scope=None, response_type="code"): 
+        """Redirects the user to obtain OAuth authorization for this service. 
+ 
+        Some providers require that you register a redirect URL with 
+        your application instead of passing one via this method. You 
+        should call this method to log the user in, and then call 
+        ``get_authenticated_user`` in the handler for your 
+        redirect URL to complete the authorization process. 
+ 
+        .. versionchanged:: 3.1 
+           Returns a `.Future` and takes an optional callback.  These are 
+           not strictly necessary as this method is synchronous, 
+           but they are supplied for consistency with 
+           `OAuthMixin.authorize_redirect`. 
+        """ 
+        args = { 
+            "redirect_uri": redirect_uri, 
+            "client_id": client_id, 
+            "response_type": response_type 
+        } 
+        if extra_params: 
+            args.update(extra_params) 
+        if scope: 
+            args['scope'] = ' '.join(scope) 
+        self.redirect( 
+            url_concat(self._OAUTH_AUTHORIZE_URL, args)) 
+        callback() 
+ 
+    def _oauth_request_token_url(self, redirect_uri=None, client_id=None, 
+                                 client_secret=None, code=None, 
+                                 extra_params=None): 
+        url = self._OAUTH_ACCESS_TOKEN_URL 
+        args = dict( 
+            redirect_uri=redirect_uri, 
+            code=code, 
+            client_id=client_id, 
+            client_secret=client_secret, 
+        ) 
+        if extra_params: 
+            args.update(extra_params) 
+        return url_concat(url, args) 
+ 
+    @_auth_return_future 
+    def oauth2_request(self, url, callback, access_token=None, 
+                       post_args=None, **args): 
+        """Fetches the given URL auth an OAuth2 access token. 
+ 
+        If the request is a POST, ``post_args`` should be provided. Query 
+        string arguments should be given as keyword arguments. 
+ 
+        Example usage: 
+ 
+        ..testcode:: 
+ 
+            class MainHandler(tornado.web.RequestHandler, 
+                              tornado.auth.FacebookGraphMixin): 
+                @tornado.web.authenticated 
+                @tornado.gen.coroutine 
+                def get(self): 
+                    new_entry = yield self.oauth2_request( 
+                        "https://graph.facebook.com/me/feed", 
+                        post_args={"message": "I am posting from my Tornado application!"}, 
+                        access_token=self.current_user["access_token"]) 
+ 
+                    if not new_entry: 
+                        # Call failed; perhaps missing permission? 
+                        yield self.authorize_redirect() 
+                        return 
+                    self.finish("Posted a message!") 
+ 
+        .. testoutput:: 
+           :hide: 
+ 
+        .. versionadded:: 4.3 
+        """ 
+        all_args = {} 
+        if access_token: 
+            all_args["access_token"] = access_token 
+            all_args.update(args) 
+ 
+        if all_args: 
+            url += "?" + urllib_parse.urlencode(all_args) 
+        callback = functools.partial(self._on_oauth2_request, callback) 
+        http = self.get_auth_http_client() 
+        if post_args is not None: 
+            http.fetch(url, method="POST", body=urllib_parse.urlencode(post_args), 
+                       callback=callback) 
+        else: 
+            http.fetch(url, callback=callback) 
+ 
+    def _on_oauth2_request(self, future, response): 
+        if response.error: 
+            future.set_exception(AuthError("Error response %s fetching %s" % 
+                                           (response.error, response.request.url))) 
+            return 
+ 
+        future.set_result(escape.json_decode(response.body)) 
+ 
+    def get_auth_http_client(self): 
+        """Returns the `.AsyncHTTPClient` instance to be used for auth requests. 
+ 
+        May be overridden by subclasses to use an HTTP client other than 
+        the default. 
+ 
+        .. versionadded:: 4.3 
+        """ 
+        return httpclient.AsyncHTTPClient() 
+ 
+ 
+class TwitterMixin(OAuthMixin): 
+    """Twitter OAuth authentication. 
+ 
+    To authenticate with Twitter, register your application with 
+    Twitter at http://twitter.com/apps. Then copy your Consumer Key 
+    and Consumer Secret to the application 
+    `~tornado.web.Application.settings` ``twitter_consumer_key`` and 
+    ``twitter_consumer_secret``. Use this mixin on the handler for the 
+    URL you registered as your application's callback URL. 
+ 
+    When your application is set up, you can use this mixin like this 
+    to authenticate the user with Twitter and get access to their stream: 
+ 
+    .. testcode:: 
+ 
+        class TwitterLoginHandler(tornado.web.RequestHandler, 
+                                  tornado.auth.TwitterMixin): 
+            @tornado.gen.coroutine 
+            def get(self): 
+                if self.get_argument("oauth_token", None): 
+                    user = yield self.get_authenticated_user() 
+                    # Save the user using e.g. set_secure_cookie() 
+                else: 
+                    yield self.authorize_redirect() 
+ 
+    .. testoutput:: 
+       :hide: 
+ 
+    The user object returned by `~OAuthMixin.get_authenticated_user` 
+    includes the attributes ``username``, ``name``, ``access_token``, 
+    and all of the custom Twitter user attributes described at 
+    https://dev.twitter.com/docs/api/1.1/get/users/show 
+    """ 
+    _OAUTH_REQUEST_TOKEN_URL = "https://api.twitter.com/oauth/request_token" 
+    _OAUTH_ACCESS_TOKEN_URL = "https://api.twitter.com/oauth/access_token" 
+    _OAUTH_AUTHORIZE_URL = "https://api.twitter.com/oauth/authorize" 
+    _OAUTH_AUTHENTICATE_URL = "https://api.twitter.com/oauth/authenticate" 
+    _OAUTH_NO_CALLBACKS = False 
+    _TWITTER_BASE_URL = "https://api.twitter.com/1.1" 
+ 
+    @return_future 
+    def authenticate_redirect(self, callback_uri=None, callback=None): 
+        """Just like `~OAuthMixin.authorize_redirect`, but 
+        auto-redirects if authorized. 
+ 
+        This is generally the right interface to use if you are using 
+        Twitter for single-sign on. 
+ 
+        .. versionchanged:: 3.1 
+           Now returns a `.Future` and takes an optional callback, for 
+           compatibility with `.gen.coroutine`. 
+        """ 
+        http = self.get_auth_http_client() 
+        http.fetch(self._oauth_request_token_url(callback_uri=callback_uri), 
+                   functools.partial( 
+                       self._on_request_token, self._OAUTH_AUTHENTICATE_URL, 
+                       None, callback)) 
+ 
+    @_auth_return_future 
+    def twitter_request(self, path, callback=None, access_token=None, 
+                        post_args=None, **args): 
+        """Fetches the given API path, e.g., ``statuses/user_timeline/btaylor`` 
+ 
+        The path should not include the format or API version number. 
+        (we automatically use JSON format and API version 1). 
+ 
+        If the request is a POST, ``post_args`` should be provided. Query 
+        string arguments should be given as keyword arguments. 
+ 
+        All the Twitter methods are documented at http://dev.twitter.com/ 
+ 
+        Many methods require an OAuth access token which you can 
+        obtain through `~OAuthMixin.authorize_redirect` and 
+        `~OAuthMixin.get_authenticated_user`. The user returned through that 
+        process includes an 'access_token' attribute that can be used 
+        to make authenticated requests via this method. Example 
+        usage: 
+ 
+        .. testcode:: 
+ 
+            class MainHandler(tornado.web.RequestHandler, 
+                              tornado.auth.TwitterMixin): 
+                @tornado.web.authenticated 
+                @tornado.gen.coroutine 
+                def get(self): 
+                    new_entry = yield self.twitter_request( 
+                        "/statuses/update", 
+                        post_args={"status": "Testing Tornado Web Server"}, 
+                        access_token=self.current_user["access_token"]) 
+                    if not new_entry: 
+                        # Call failed; perhaps missing permission? 
+                        yield self.authorize_redirect() 
+                        return 
+                    self.finish("Posted a message!") 
+ 
+        .. testoutput:: 
+           :hide: 
+ 
+        """ 
+        if path.startswith('http:') or path.startswith('https:'): 
+            # Raw urls are useful for e.g. search which doesn't follow the 
+            # usual pattern: http://search.twitter.com/search.json 
+            url = path 
+        else: 
+            url = self._TWITTER_BASE_URL + path + ".json" 
+        # Add the OAuth resource request signature if we have credentials 
+        if access_token: 
+            all_args = {} 
+            all_args.update(args) 
+            all_args.update(post_args or {}) 
+            method = "POST" if post_args is not None else "GET" 
+            oauth = self._oauth_request_parameters( 
+                url, access_token, all_args, method=method) 
+            args.update(oauth) 
+        if args: 
+            url += "?" + urllib_parse.urlencode(args) 
+        http = self.get_auth_http_client() 
+        http_callback = functools.partial(self._on_twitter_request, callback) 
+        if post_args is not None: 
+            http.fetch(url, method="POST", body=urllib_parse.urlencode(post_args), 
+                       callback=http_callback) 
+        else: 
+            http.fetch(url, callback=http_callback) 
+ 
+    def _on_twitter_request(self, future, response): 
+        if response.error: 
+            future.set_exception(AuthError( 
+                "Error response %s fetching %s" % (response.error, 
+                                                   response.request.url))) 
+            return 
+        future.set_result(escape.json_decode(response.body)) 
+ 
+    def _oauth_consumer_token(self): 
+        self.require_setting("twitter_consumer_key", "Twitter OAuth") 
+        self.require_setting("twitter_consumer_secret", "Twitter OAuth") 
+        return dict( 
+            key=self.settings["twitter_consumer_key"], 
+            secret=self.settings["twitter_consumer_secret"]) 
+ 
+    @gen.coroutine 
+    def _oauth_get_user_future(self, access_token): 
+        user = yield self.twitter_request( 
+            "/account/verify_credentials", 
+            access_token=access_token) 
+        if user: 
+            user["username"] = user["screen_name"] 
+        raise gen.Return(user) 
+ 
+ 
+class GoogleOAuth2Mixin(OAuth2Mixin): 
+    """Google authentication using OAuth2. 
+ 
+    In order to use, register your application with Google and copy the 
+    relevant parameters to your application settings. 
+ 
+    * Go to the Google Dev Console at http://console.developers.google.com 
+    * Select a project, or create a new one. 
+    * In the sidebar on the left, select APIs & Auth. 
+    * In the list of APIs, find the Google+ API service and set it to ON. 
+    * In the sidebar on the left, select Credentials. 
+    * In the OAuth section of the page, select Create New Client ID. 
+    * Set the Redirect URI to point to your auth handler 
+    * Copy the "Client secret" and "Client ID" to the application settings as 
+      {"google_oauth": {"key": CLIENT_ID, "secret": CLIENT_SECRET}} 
+ 
+    .. versionadded:: 3.2 
+    """ 
+    _OAUTH_AUTHORIZE_URL = "https://accounts.google.com/o/oauth2/auth" 
+    _OAUTH_ACCESS_TOKEN_URL = "https://accounts.google.com/o/oauth2/token" 
+    _OAUTH_USERINFO_URL = "https://www.googleapis.com/oauth2/v1/userinfo" 
+    _OAUTH_NO_CALLBACKS = False 
+    _OAUTH_SETTINGS_KEY = 'google_oauth' 
+ 
+    @_auth_return_future 
+    def get_authenticated_user(self, redirect_uri, code, callback): 
+        """Handles the login for the Google user, returning an access token. 
+ 
+        The result is a dictionary containing an ``access_token`` field 
+        ([among others](https://developers.google.com/identity/protocols/OAuth2WebServer#handlingtheresponse)). 
+        Unlike other ``get_authenticated_user`` methods in this package, 
+        this method does not return any additional information about the user. 
+        The returned access token can be used with `OAuth2Mixin.oauth2_request` 
+        to request additional information (perhaps from 
+        ``https://www.googleapis.com/oauth2/v2/userinfo``) 
+ 
+        Example usage: 
+ 
+        .. testcode:: 
+ 
+            class GoogleOAuth2LoginHandler(tornado.web.RequestHandler, 
+                                           tornado.auth.GoogleOAuth2Mixin): 
+                @tornado.gen.coroutine 
+                def get(self): 
+                    if self.get_argument('code', False): 
+                        access = yield self.get_authenticated_user( 
+                            redirect_uri='http://your.site.com/auth/google', 
+                            code=self.get_argument('code')) 
+                        user = yield self.oauth2_request( 
+                            "https://www.googleapis.com/oauth2/v1/userinfo", 
+                            access_token=access["access_token"]) 
+                        # Save the user and access token with 
+                        # e.g. set_secure_cookie. 
+                    else: 
+                        yield self.authorize_redirect( 
+                            redirect_uri='http://your.site.com/auth/google', 
+                            client_id=self.settings['google_oauth']['key'], 
+                            scope=['profile', 'email'], 
+                            response_type='code', 
+                            extra_params={'approval_prompt': 'auto'}) 
+ 
+        .. testoutput:: 
+           :hide: 
+ 
+        """ 
+        http = self.get_auth_http_client() 
+        body = urllib_parse.urlencode({ 
+            "redirect_uri": redirect_uri, 
+            "code": code, 
+            "client_id": self.settings[self._OAUTH_SETTINGS_KEY]['key'], 
+            "client_secret": self.settings[self._OAUTH_SETTINGS_KEY]['secret'], 
+            "grant_type": "authorization_code", 
+        }) 
+ 
+        http.fetch(self._OAUTH_ACCESS_TOKEN_URL, 
+                   functools.partial(self._on_access_token, callback), 
+                   method="POST", headers={'Content-Type': 'application/x-www-form-urlencoded'}, body=body) 
+ 
+    def _on_access_token(self, future, response): 
+        """Callback function for the exchange to the access token.""" 
+        if response.error: 
+            future.set_exception(AuthError('Google auth error: %s' % str(response))) 
+            return 
+ 
+        args = escape.json_decode(response.body) 
+        future.set_result(args) 
+ 
+ 
+class FacebookGraphMixin(OAuth2Mixin): 
+    """Facebook authentication using the new Graph API and OAuth2.""" 
+    _OAUTH_ACCESS_TOKEN_URL = "https://graph.facebook.com/oauth/access_token?" 
+    _OAUTH_AUTHORIZE_URL = "https://www.facebook.com/dialog/oauth?" 
+    _OAUTH_NO_CALLBACKS = False 
+    _FACEBOOK_BASE_URL = "https://graph.facebook.com" 
+ 
+    @_auth_return_future 
+    def get_authenticated_user(self, redirect_uri, client_id, client_secret, 
+                               code, callback, extra_fields=None): 
+        """Handles the login for the Facebook user, returning a user object. 
+ 
+        Example usage: 
+ 
+        .. testcode:: 
+ 
+            class FacebookGraphLoginHandler(tornado.web.RequestHandler, 
+                                            tornado.auth.FacebookGraphMixin): 
+              @tornado.gen.coroutine 
+              def get(self): 
+                  if self.get_argument("code", False): 
+                      user = yield self.get_authenticated_user( 
+                          redirect_uri='/auth/facebookgraph/', 
+                          client_id=self.settings["facebook_api_key"], 
+                          client_secret=self.settings["facebook_secret"], 
+                          code=self.get_argument("code")) 
+                      # Save the user with e.g. set_secure_cookie 
+                  else: 
+                      yield self.authorize_redirect( 
+                          redirect_uri='/auth/facebookgraph/', 
+                          client_id=self.settings["facebook_api_key"], 
+                          extra_params={"scope": "read_stream,offline_access"}) 
+ 
+        .. testoutput:: 
+           :hide: 
+ 
+        This method returns a dictionary which may contain the following fields: 
+ 
+        * ``access_token``, a string which may be passed to `facebook_request` 
+        * ``session_expires``, an integer encoded as a string representing 
+          the time until the access token expires in seconds. This field should 
+          be used like ``int(user['session_expires'])``; in a future version of 
+          Tornado it will change from a string to an integer. 
+        * ``id``, ``name``, ``first_name``, ``last_name``, ``locale``, ``picture``, 
+          ``link``, plus any fields named in the ``extra_fields`` argument. These 
+          fields are copied from the Facebook graph API `user object <https://developers.facebook.com/docs/graph-api/reference/user>`_ 
+ 
+        .. versionchanged:: 4.5 
+           The ``session_expires`` field was updated to support changes made to the 
+           Facebook API in March 2017. 
+        """ 
+        http = self.get_auth_http_client() 
+        args = { 
+            "redirect_uri": redirect_uri, 
+            "code": code, 
+            "client_id": client_id, 
+            "client_secret": client_secret, 
+        } 
+ 
+        fields = set(['id', 'name', 'first_name', 'last_name', 
+                      'locale', 'picture', 'link']) 
+        if extra_fields: 
+            fields.update(extra_fields) 
+ 
+        http.fetch(self._oauth_request_token_url(**args), 
+                   functools.partial(self._on_access_token, redirect_uri, client_id, 
+                                     client_secret, callback, fields)) 
+ 
+    def _on_access_token(self, redirect_uri, client_id, client_secret, 
+                         future, fields, response): 
+        if response.error: 
+            future.set_exception(AuthError('Facebook auth error: %s' % str(response))) 
+            return 
+ 
+        args = escape.json_decode(response.body) 
+        session = { 
+            "access_token": args.get("access_token"), 
+            "expires_in": args.get("expires_in") 
+        } 
+ 
+        self.facebook_request( 
+            path="/me", 
+            callback=functools.partial( 
+                self._on_get_user_info, future, session, fields), 
+            access_token=session["access_token"], 
+            appsecret_proof=hmac.new(key=client_secret.encode('utf8'), 
+                                     msg=session["access_token"].encode('utf8'), 
+                                     digestmod=hashlib.sha256).hexdigest(), 
+            fields=",".join(fields) 
+        ) 
+ 
+    def _on_get_user_info(self, future, session, fields, user): 
+        if user is None: 
+            future.set_result(None) 
+            return 
+ 
+        fieldmap = {} 
+        for field in fields: 
+            fieldmap[field] = user.get(field) 
+ 
+        # session_expires is converted to str for compatibility with 
+        # older versions in which the server used url-encoding and 
+        # this code simply returned the string verbatim. 
+        # This should change in Tornado 5.0. 
+        fieldmap.update({"access_token": session["access_token"], 
+                         "session_expires": str(session.get("expires_in"))}) 
+        future.set_result(fieldmap) 
+ 
+    @_auth_return_future 
+    def facebook_request(self, path, callback, access_token=None, 
+                         post_args=None, **args): 
+        """Fetches the given relative API path, e.g., "/btaylor/picture" 
+ 
+        If the request is a POST, ``post_args`` should be provided. Query 
+        string arguments should be given as keyword arguments. 
+ 
+        An introduction to the Facebook Graph API can be found at 
+        http://developers.facebook.com/docs/api 
+ 
+        Many methods require an OAuth access token which you can 
+        obtain through `~OAuth2Mixin.authorize_redirect` and 
+        `get_authenticated_user`. The user returned through that 
+        process includes an ``access_token`` attribute that can be 
+        used to make authenticated requests via this method. 
+ 
+        Example usage: 
+ 
+        ..testcode:: 
+ 
+            class MainHandler(tornado.web.RequestHandler, 
+                              tornado.auth.FacebookGraphMixin): 
+                @tornado.web.authenticated 
+                @tornado.gen.coroutine 
+                def get(self): 
+                    new_entry = yield self.facebook_request( 
+                        "/me/feed", 
+                        post_args={"message": "I am posting from my Tornado application!"}, 
+                        access_token=self.current_user["access_token"]) 
+ 
+                    if not new_entry: 
+                        # Call failed; perhaps missing permission? 
+                        yield self.authorize_redirect() 
+                        return 
+                    self.finish("Posted a message!") 
+ 
+        .. testoutput:: 
+           :hide: 
+ 
+        The given path is relative to ``self._FACEBOOK_BASE_URL``, 
+        by default "https://graph.facebook.com". 
+ 
+        This method is a wrapper around `OAuth2Mixin.oauth2_request`; 
+        the only difference is that this method takes a relative path, 
+        while ``oauth2_request`` takes a complete url. 
+ 
+        .. versionchanged:: 3.1 
+           Added the ability to override ``self._FACEBOOK_BASE_URL``. 
+        """ 
+        url = self._FACEBOOK_BASE_URL + path 
+        # Thanks to the _auth_return_future decorator, our "callback" 
+        # argument is a Future, which we cannot pass as a callback to 
+        # oauth2_request. Instead, have oauth2_request return a 
+        # future and chain them together. 
+        oauth_future = self.oauth2_request(url, access_token=access_token, 
+                                           post_args=post_args, **args) 
+        chain_future(oauth_future, callback) 
+ 
+ 
+def _oauth_signature(consumer_token, method, url, parameters={}, token=None): 
+    """Calculates the HMAC-SHA1 OAuth signature for the given request. 
+ 
+    See http://oauth.net/core/1.0/#signing_process 
+    """ 
+    parts = urlparse.urlparse(url) 
+    scheme, netloc, path = parts[:3] 
+    normalized_url = scheme.lower() + "://" + netloc.lower() + path 
+ 
+    base_elems = [] 
+    base_elems.append(method.upper()) 
+    base_elems.append(normalized_url) 
+    base_elems.append("&".join("%s=%s" % (k, _oauth_escape(str(v))) 
+                               for k, v in sorted(parameters.items()))) 
+    base_string = "&".join(_oauth_escape(e) for e in base_elems) 
+ 
+    key_elems = [escape.utf8(consumer_token["secret"])] 
+    key_elems.append(escape.utf8(token["secret"] if token else "")) 
+    key = b"&".join(key_elems) 
+ 
+    hash = hmac.new(key, escape.utf8(base_string), hashlib.sha1) 
+    return binascii.b2a_base64(hash.digest())[:-1] 
+ 
+ 
+def _oauth10a_signature(consumer_token, method, url, parameters={}, token=None): 
+    """Calculates the HMAC-SHA1 OAuth 1.0a signature for the given request. 
+ 
+    See http://oauth.net/core/1.0a/#signing_process 
+    """ 
+    parts = urlparse.urlparse(url) 
+    scheme, netloc, path = parts[:3] 
+    normalized_url = scheme.lower() + "://" + netloc.lower() + path 
+ 
+    base_elems = [] 
+    base_elems.append(method.upper()) 
+    base_elems.append(normalized_url) 
+    base_elems.append("&".join("%s=%s" % (k, _oauth_escape(str(v))) 
+                               for k, v in sorted(parameters.items()))) 
+ 
+    base_string = "&".join(_oauth_escape(e) for e in base_elems) 
+    key_elems = [escape.utf8(urllib_parse.quote(consumer_token["secret"], safe='~'))] 
+    key_elems.append(escape.utf8(urllib_parse.quote(token["secret"], safe='~') if token else "")) 
+    key = b"&".join(key_elems) 
+ 
+    hash = hmac.new(key, escape.utf8(base_string), hashlib.sha1) 
+    return binascii.b2a_base64(hash.digest())[:-1] 
+ 
+ 
+def _oauth_escape(val): 
+    if isinstance(val, unicode_type): 
+        val = val.encode("utf-8") 
+    return urllib_parse.quote(val, safe="~") 
+ 
+ 
+def _oauth_parse_response(body): 
+    # I can't find an officially-defined encoding for oauth responses and 
+    # have never seen anyone use non-ascii.  Leave the response in a byte 
+    # string for python 2, and use utf8 on python 3. 
+    body = escape.native_str(body) 
+    p = urlparse.parse_qs(body, keep_blank_values=False) 
+    token = dict(key=p["oauth_token"][0], secret=p["oauth_token_secret"][0]) 
+ 
+    # Add the extra parameters the Provider included to the token 
+    special = ("oauth_token", "oauth_token_secret") 
+    token.update((k, p[k][0]) for k in p if k not in special) 
+    return token 
diff --git a/contrib/python/tornado/tornado-4/tornado/autoreload.py b/contrib/python/tornado/tornado-4/tornado/autoreload.py
index 60571efe71..fb4a7d9b83 100644
--- a/contrib/python/tornado/tornado-4/tornado/autoreload.py
+++ b/contrib/python/tornado/tornado-4/tornado/autoreload.py
@@ -1,334 +1,334 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Automatically restart the server when a source file is modified.
-
-Most applications should not access this module directly.  Instead,
-pass the keyword argument ``autoreload=True`` to the
-`tornado.web.Application` constructor (or ``debug=True``, which
-enables this setting and several others).  This will enable autoreload
-mode as well as checking for changes to templates and static
-resources.  Note that restarting is a destructive operation and any
-requests in progress will be aborted when the process restarts.  (If
-you want to disable autoreload while using other debug-mode features,
-pass both ``debug=True`` and ``autoreload=False``).
-
-This module can also be used as a command-line wrapper around scripts
-such as unit test runners.  See the `main` method for details.
-
-The command-line wrapper and Application debug modes can be used together.
-This combination is encouraged as the wrapper catches syntax errors and
-other import-time failures, while debug mode catches changes once
-the server has started.
-
-This module depends on `.IOLoop`, so it will not work in WSGI applications
-and Google App Engine.  It also will not work correctly when `.HTTPServer`'s
-multi-process mode is used.
-
-Reloading loses any Python interpreter command-line arguments (e.g. ``-u``)
-because it re-executes Python using ``sys.executable`` and ``sys.argv``.
-Additionally, modifying these variables will cause reloading to behave
-incorrectly.
-
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import os
-import sys
-
-# sys.path handling
-# -----------------
-#
-# If a module is run with "python -m", the current directory (i.e. "")
-# is automatically prepended to sys.path, but not if it is run as
-# "path/to/file.py".  The processing for "-m" rewrites the former to
-# the latter, so subsequent executions won't have the same path as the
-# original.
-#
-# Conversely, when run as path/to/file.py, the directory containing
-# file.py gets added to the path, which can cause confusion as imports
-# may become relative in spite of the future import.
-#
-# We address the former problem by setting the $PYTHONPATH environment
-# variable before re-execution so the new process will see the correct
-# path.  We attempt to address the latter problem when tornado.autoreload
-# is run as __main__, although we can't fix the general case because
-# we cannot reliably reconstruct the original command line
-# (http://bugs.python.org/issue14208).
-
-if __name__ == "__main__":
-    # This sys.path manipulation must come before our imports (as much
-    # as possible - if we introduced a tornado.sys or tornado.os
-    # module we'd be in trouble), or else our imports would become
-    # relative again despite the future import.
-    #
-    # There is a separate __main__ block at the end of the file to call main().
-    if sys.path[0] == os.path.dirname(__file__):
-        del sys.path[0]
-
-import functools
-import logging
-import os
-import pkgutil  # type: ignore
-import sys
-import traceback
-import types
-import subprocess
-import weakref
-
-from tornado import ioloop
-from tornado.log import gen_log
-from tornado import process
-from tornado.util import exec_in
-
-try:
-    import signal
-except ImportError:
-    signal = None
-
-# os.execv is broken on Windows and can't properly parse command line
-# arguments and executable name if they contain whitespaces. subprocess
-# fixes that behavior.
-_has_execv = sys.platform != 'win32'
-
-_watched_files = set()
-_reload_hooks = []
-_reload_attempted = False
-_io_loops = weakref.WeakKeyDictionary()  # type: ignore
-
-
-def start(io_loop=None, check_time=500):
-    """Begins watching source files for changes.
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-    """
-    io_loop = io_loop or ioloop.IOLoop.current()
-    if io_loop in _io_loops:
-        return
-    _io_loops[io_loop] = True
-    if len(_io_loops) > 1:
-        gen_log.warning("tornado.autoreload started more than once in the same process")
-    modify_times = {}
-    callback = functools.partial(_reload_on_update, modify_times)
-    scheduler = ioloop.PeriodicCallback(callback, check_time, io_loop=io_loop)
-    scheduler.start()
-
-
-def wait():
-    """Wait for a watched file to change, then restart the process.
-
-    Intended to be used at the end of scripts like unit test runners,
-    to run the tests again after any source file changes (but see also
-    the command-line interface in `main`)
-    """
-    io_loop = ioloop.IOLoop()
-    start(io_loop)
-    io_loop.start()
-
-
-def watch(filename):
-    """Add a file to the watch list.
-
-    All imported modules are watched by default.
-    """
-    _watched_files.add(filename)
-
-
-def add_reload_hook(fn):
-    """Add a function to be called before reloading the process.
-
-    Note that for open file and socket handles it is generally
-    preferable to set the ``FD_CLOEXEC`` flag (using `fcntl` or
-    ``tornado.platform.auto.set_close_exec``) instead
-    of using a reload hook to close them.
-    """
-    _reload_hooks.append(fn)
-
-
-def _reload_on_update(modify_times):
-    if _reload_attempted:
-        # We already tried to reload and it didn't work, so don't try again.
-        return
-    if process.task_id() is not None:
-        # We're in a child process created by fork_processes.  If child
-        # processes restarted themselves, they'd all restart and then
-        # all call fork_processes again.
-        return
-    for module in list(sys.modules.values()):
-        # Some modules play games with sys.modules (e.g. email/__init__.py
-        # in the standard library), and occasionally this can cause strange
-        # failures in getattr.  Just ignore anything that's not an ordinary
-        # module.
-        if not isinstance(module, types.ModuleType):
-            continue
-        path = getattr(module, "__file__", None)
-        if not path:
-            continue
-        if path.endswith(".pyc") or path.endswith(".pyo"):
-            path = path[:-1]
-        _check_file(modify_times, path)
-    for path in _watched_files:
-        _check_file(modify_times, path)
-
-
-def _check_file(modify_times, path):
-    try:
-        modified = os.stat(path).st_mtime
-    except Exception:
-        return
-    if path not in modify_times:
-        modify_times[path] = modified
-        return
-    if modify_times[path] != modified:
-        gen_log.info("%s modified; restarting server", path)
-        _reload()
-
-
-def _reload():
-    global _reload_attempted
-    _reload_attempted = True
-    for fn in _reload_hooks:
-        fn()
-    if hasattr(signal, "setitimer"):
-        # Clear the alarm signal set by
-        # ioloop.set_blocking_log_threshold so it doesn't fire
-        # after the exec.
-        signal.setitimer(signal.ITIMER_REAL, 0, 0)
-    # sys.path fixes: see comments at top of file.  If sys.path[0] is an empty
-    # string, we were (probably) invoked with -m and the effective path
-    # is about to change on re-exec.  Add the current directory to $PYTHONPATH
-    # to ensure that the new process sees the same path we did.
-    path_prefix = '.' + os.pathsep
-    if (sys.path[0] == '' and
-            not os.environ.get("PYTHONPATH", "").startswith(path_prefix)):
-        os.environ["PYTHONPATH"] = (path_prefix +
-                                    os.environ.get("PYTHONPATH", ""))
-    if not _has_execv:
-        subprocess.Popen([sys.executable] + sys.argv)
-        sys.exit(0)
-    else:
-        try:
-            os.execv(sys.executable, [sys.executable] + sys.argv)
-        except OSError:
-            # Mac OS X versions prior to 10.6 do not support execv in
-            # a process that contains multiple threads.  Instead of
-            # re-executing in the current process, start a new one
-            # and cause the current process to exit.  This isn't
-            # ideal since the new process is detached from the parent
-            # terminal and thus cannot easily be killed with ctrl-C,
-            # but it's better than not being able to autoreload at
-            # all.
-            # Unfortunately the errno returned in this case does not
-            # appear to be consistent, so we can't easily check for
-            # this error specifically.
-            os.spawnv(os.P_NOWAIT, sys.executable,
-                      [sys.executable] + sys.argv)
-            # At this point the IOLoop has been closed and finally
-            # blocks will experience errors if we allow the stack to
-            # unwind, so just exit uncleanly.
-            os._exit(0)
-
-
-_USAGE = """\
-Usage:
-  python -m tornado.autoreload -m module.to.run [args...]
-  python -m tornado.autoreload path/to/script.py [args...]
-"""
-
-
-def main():
-    """Command-line wrapper to re-run a script whenever its source changes.
-
-    Scripts may be specified by filename or module name::
-
-        python -m tornado.autoreload -m tornado.test.runtests
-        python -m tornado.autoreload tornado/test/runtests.py
-
-    Running a script with this wrapper is similar to calling
-    `tornado.autoreload.wait` at the end of the script, but this wrapper
-    can catch import-time problems like syntax errors that would otherwise
-    prevent the script from reaching its call to `wait`.
-    """
-    original_argv = sys.argv
-    sys.argv = sys.argv[:]
-    if len(sys.argv) >= 3 and sys.argv[1] == "-m":
-        mode = "module"
-        module = sys.argv[2]
-        del sys.argv[1:3]
-    elif len(sys.argv) >= 2:
-        mode = "script"
-        script = sys.argv[1]
-        sys.argv = sys.argv[1:]
-    else:
-        print(_USAGE, file=sys.stderr)
-        sys.exit(1)
-
-    try:
-        if mode == "module":
-            import runpy
-            runpy.run_module(module, run_name="__main__", alter_sys=True)
-        elif mode == "script":
-            with open(script) as f:
-                # Execute the script in our namespace instead of creating
-                # a new one so that something that tries to import __main__
-                # (e.g. the unittest module) will see names defined in the
-                # script instead of just those defined in this module.
-                global __file__
-                __file__ = script
-                # If __package__ is defined, imports may be incorrectly
-                # interpreted as relative to this module.
-                global __package__
-                del __package__
-                exec_in(f.read(), globals(), globals())
-    except SystemExit as e:
-        logging.basicConfig()
-        gen_log.info("Script exited with status %s", e.code)
-    except Exception as e:
-        logging.basicConfig()
-        gen_log.warning("Script exited with uncaught exception", exc_info=True)
-        # If an exception occurred at import time, the file with the error
-        # never made it into sys.modules and so we won't know to watch it.
-        # Just to make sure we've covered everything, walk the stack trace
-        # from the exception and watch every file.
-        for (filename, lineno, name, line) in traceback.extract_tb(sys.exc_info()[2]):
-            watch(filename)
-        if isinstance(e, SyntaxError):
-            # SyntaxErrors are special:  their innermost stack frame is fake
-            # so extract_tb won't see it and we have to get the filename
-            # from the exception object.
-            watch(e.filename)
-    else:
-        logging.basicConfig()
-        gen_log.info("Script exited normally")
-    # restore sys.argv so subsequent executions will include autoreload
-    sys.argv = original_argv
-
-    if mode == 'module':
-        # runpy did a fake import of the module as __main__, but now it's
-        # no longer in sys.modules.  Figure out where it is and watch it.
-        loader = pkgutil.get_loader(module)
-        if loader is not None:
-            watch(loader.get_filename())
-
-    wait()
-
-
-if __name__ == "__main__":
-    # See also the other __main__ block at the top of the file, which modifies
-    # sys.path before our imports
-    main()
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Automatically restart the server when a source file is modified. 
+ 
+Most applications should not access this module directly.  Instead, 
+pass the keyword argument ``autoreload=True`` to the 
+`tornado.web.Application` constructor (or ``debug=True``, which 
+enables this setting and several others).  This will enable autoreload 
+mode as well as checking for changes to templates and static 
+resources.  Note that restarting is a destructive operation and any 
+requests in progress will be aborted when the process restarts.  (If 
+you want to disable autoreload while using other debug-mode features, 
+pass both ``debug=True`` and ``autoreload=False``). 
+ 
+This module can also be used as a command-line wrapper around scripts 
+such as unit test runners.  See the `main` method for details. 
+ 
+The command-line wrapper and Application debug modes can be used together. 
+This combination is encouraged as the wrapper catches syntax errors and 
+other import-time failures, while debug mode catches changes once 
+the server has started. 
+ 
+This module depends on `.IOLoop`, so it will not work in WSGI applications 
+and Google App Engine.  It also will not work correctly when `.HTTPServer`'s 
+multi-process mode is used. 
+ 
+Reloading loses any Python interpreter command-line arguments (e.g. ``-u``) 
+because it re-executes Python using ``sys.executable`` and ``sys.argv``. 
+Additionally, modifying these variables will cause reloading to behave 
+incorrectly. 
+ 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import os 
+import sys 
+ 
+# sys.path handling 
+# ----------------- 
+# 
+# If a module is run with "python -m", the current directory (i.e. "") 
+# is automatically prepended to sys.path, but not if it is run as 
+# "path/to/file.py".  The processing for "-m" rewrites the former to 
+# the latter, so subsequent executions won't have the same path as the 
+# original. 
+# 
+# Conversely, when run as path/to/file.py, the directory containing 
+# file.py gets added to the path, which can cause confusion as imports 
+# may become relative in spite of the future import. 
+# 
+# We address the former problem by setting the $PYTHONPATH environment 
+# variable before re-execution so the new process will see the correct 
+# path.  We attempt to address the latter problem when tornado.autoreload 
+# is run as __main__, although we can't fix the general case because 
+# we cannot reliably reconstruct the original command line 
+# (http://bugs.python.org/issue14208). 
+ 
+if __name__ == "__main__": 
+    # This sys.path manipulation must come before our imports (as much 
+    # as possible - if we introduced a tornado.sys or tornado.os 
+    # module we'd be in trouble), or else our imports would become 
+    # relative again despite the future import. 
+    # 
+    # There is a separate __main__ block at the end of the file to call main(). 
+    if sys.path[0] == os.path.dirname(__file__): 
+        del sys.path[0] 
+ 
+import functools 
+import logging 
+import os 
+import pkgutil  # type: ignore 
+import sys 
+import traceback 
+import types 
+import subprocess 
+import weakref 
+ 
+from tornado import ioloop 
+from tornado.log import gen_log 
+from tornado import process 
+from tornado.util import exec_in 
+ 
+try: 
+    import signal 
+except ImportError: 
+    signal = None 
+ 
+# os.execv is broken on Windows and can't properly parse command line 
+# arguments and executable name if they contain whitespaces. subprocess 
+# fixes that behavior. 
+_has_execv = sys.platform != 'win32' 
+ 
+_watched_files = set() 
+_reload_hooks = [] 
+_reload_attempted = False 
+_io_loops = weakref.WeakKeyDictionary()  # type: ignore 
+ 
+ 
+def start(io_loop=None, check_time=500): 
+    """Begins watching source files for changes. 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+    """ 
+    io_loop = io_loop or ioloop.IOLoop.current() 
+    if io_loop in _io_loops: 
+        return 
+    _io_loops[io_loop] = True 
+    if len(_io_loops) > 1: 
+        gen_log.warning("tornado.autoreload started more than once in the same process") 
+    modify_times = {} 
+    callback = functools.partial(_reload_on_update, modify_times) 
+    scheduler = ioloop.PeriodicCallback(callback, check_time, io_loop=io_loop) 
+    scheduler.start() 
+ 
+ 
+def wait(): 
+    """Wait for a watched file to change, then restart the process. 
+ 
+    Intended to be used at the end of scripts like unit test runners, 
+    to run the tests again after any source file changes (but see also 
+    the command-line interface in `main`) 
+    """ 
+    io_loop = ioloop.IOLoop() 
+    start(io_loop) 
+    io_loop.start() 
+ 
+ 
+def watch(filename): 
+    """Add a file to the watch list. 
+ 
+    All imported modules are watched by default. 
+    """ 
+    _watched_files.add(filename) 
+ 
+ 
+def add_reload_hook(fn): 
+    """Add a function to be called before reloading the process. 
+ 
+    Note that for open file and socket handles it is generally 
+    preferable to set the ``FD_CLOEXEC`` flag (using `fcntl` or 
+    ``tornado.platform.auto.set_close_exec``) instead 
+    of using a reload hook to close them. 
+    """ 
+    _reload_hooks.append(fn) 
+ 
+ 
+def _reload_on_update(modify_times): 
+    if _reload_attempted: 
+        # We already tried to reload and it didn't work, so don't try again. 
+        return 
+    if process.task_id() is not None: 
+        # We're in a child process created by fork_processes.  If child 
+        # processes restarted themselves, they'd all restart and then 
+        # all call fork_processes again. 
+        return 
+    for module in list(sys.modules.values()): 
+        # Some modules play games with sys.modules (e.g. email/__init__.py 
+        # in the standard library), and occasionally this can cause strange 
+        # failures in getattr.  Just ignore anything that's not an ordinary 
+        # module. 
+        if not isinstance(module, types.ModuleType): 
+            continue 
+        path = getattr(module, "__file__", None) 
+        if not path: 
+            continue 
+        if path.endswith(".pyc") or path.endswith(".pyo"): 
+            path = path[:-1] 
+        _check_file(modify_times, path) 
+    for path in _watched_files: 
+        _check_file(modify_times, path) 
+ 
+ 
+def _check_file(modify_times, path): 
+    try: 
+        modified = os.stat(path).st_mtime 
+    except Exception: 
+        return 
+    if path not in modify_times: 
+        modify_times[path] = modified 
+        return 
+    if modify_times[path] != modified: 
+        gen_log.info("%s modified; restarting server", path) 
+        _reload() 
+ 
+ 
+def _reload(): 
+    global _reload_attempted 
+    _reload_attempted = True 
+    for fn in _reload_hooks: 
+        fn() 
+    if hasattr(signal, "setitimer"): 
+        # Clear the alarm signal set by 
+        # ioloop.set_blocking_log_threshold so it doesn't fire 
+        # after the exec. 
+        signal.setitimer(signal.ITIMER_REAL, 0, 0) 
+    # sys.path fixes: see comments at top of file.  If sys.path[0] is an empty 
+    # string, we were (probably) invoked with -m and the effective path 
+    # is about to change on re-exec.  Add the current directory to $PYTHONPATH 
+    # to ensure that the new process sees the same path we did. 
+    path_prefix = '.' + os.pathsep 
+    if (sys.path[0] == '' and 
+            not os.environ.get("PYTHONPATH", "").startswith(path_prefix)): 
+        os.environ["PYTHONPATH"] = (path_prefix + 
+                                    os.environ.get("PYTHONPATH", "")) 
+    if not _has_execv: 
+        subprocess.Popen([sys.executable] + sys.argv) 
+        sys.exit(0) 
+    else: 
+        try: 
+            os.execv(sys.executable, [sys.executable] + sys.argv) 
+        except OSError: 
+            # Mac OS X versions prior to 10.6 do not support execv in 
+            # a process that contains multiple threads.  Instead of 
+            # re-executing in the current process, start a new one 
+            # and cause the current process to exit.  This isn't 
+            # ideal since the new process is detached from the parent 
+            # terminal and thus cannot easily be killed with ctrl-C, 
+            # but it's better than not being able to autoreload at 
+            # all. 
+            # Unfortunately the errno returned in this case does not 
+            # appear to be consistent, so we can't easily check for 
+            # this error specifically. 
+            os.spawnv(os.P_NOWAIT, sys.executable, 
+                      [sys.executable] + sys.argv) 
+            # At this point the IOLoop has been closed and finally 
+            # blocks will experience errors if we allow the stack to 
+            # unwind, so just exit uncleanly. 
+            os._exit(0) 
+ 
+ 
+_USAGE = """\ 
+Usage: 
+  python -m tornado.autoreload -m module.to.run [args...] 
+  python -m tornado.autoreload path/to/script.py [args...] 
+""" 
+ 
+ 
+def main(): 
+    """Command-line wrapper to re-run a script whenever its source changes. 
+ 
+    Scripts may be specified by filename or module name:: 
+ 
+        python -m tornado.autoreload -m tornado.test.runtests 
+        python -m tornado.autoreload tornado/test/runtests.py 
+ 
+    Running a script with this wrapper is similar to calling 
+    `tornado.autoreload.wait` at the end of the script, but this wrapper 
+    can catch import-time problems like syntax errors that would otherwise 
+    prevent the script from reaching its call to `wait`. 
+    """ 
+    original_argv = sys.argv 
+    sys.argv = sys.argv[:] 
+    if len(sys.argv) >= 3 and sys.argv[1] == "-m": 
+        mode = "module" 
+        module = sys.argv[2] 
+        del sys.argv[1:3] 
+    elif len(sys.argv) >= 2: 
+        mode = "script" 
+        script = sys.argv[1] 
+        sys.argv = sys.argv[1:] 
+    else: 
+        print(_USAGE, file=sys.stderr) 
+        sys.exit(1) 
+ 
+    try: 
+        if mode == "module": 
+            import runpy 
+            runpy.run_module(module, run_name="__main__", alter_sys=True) 
+        elif mode == "script": 
+            with open(script) as f: 
+                # Execute the script in our namespace instead of creating 
+                # a new one so that something that tries to import __main__ 
+                # (e.g. the unittest module) will see names defined in the 
+                # script instead of just those defined in this module. 
+                global __file__ 
+                __file__ = script 
+                # If __package__ is defined, imports may be incorrectly 
+                # interpreted as relative to this module. 
+                global __package__ 
+                del __package__ 
+                exec_in(f.read(), globals(), globals()) 
+    except SystemExit as e: 
+        logging.basicConfig() 
+        gen_log.info("Script exited with status %s", e.code) 
+    except Exception as e: 
+        logging.basicConfig() 
+        gen_log.warning("Script exited with uncaught exception", exc_info=True) 
+        # If an exception occurred at import time, the file with the error 
+        # never made it into sys.modules and so we won't know to watch it. 
+        # Just to make sure we've covered everything, walk the stack trace 
+        # from the exception and watch every file. 
+        for (filename, lineno, name, line) in traceback.extract_tb(sys.exc_info()[2]): 
+            watch(filename) 
+        if isinstance(e, SyntaxError): 
+            # SyntaxErrors are special:  their innermost stack frame is fake 
+            # so extract_tb won't see it and we have to get the filename 
+            # from the exception object. 
+            watch(e.filename) 
+    else: 
+        logging.basicConfig() 
+        gen_log.info("Script exited normally") 
+    # restore sys.argv so subsequent executions will include autoreload 
+    sys.argv = original_argv 
+ 
+    if mode == 'module': 
+        # runpy did a fake import of the module as __main__, but now it's 
+        # no longer in sys.modules.  Figure out where it is and watch it. 
+        loader = pkgutil.get_loader(module) 
+        if loader is not None: 
+            watch(loader.get_filename()) 
+ 
+    wait() 
+ 
+ 
+if __name__ == "__main__": 
+    # See also the other __main__ block at the top of the file, which modifies 
+    # sys.path before our imports 
+    main() 
diff --git a/contrib/python/tornado/tornado-4/tornado/concurrent.py b/contrib/python/tornado/tornado-4/tornado/concurrent.py
index 667e6b1788..dc82ff0009 100644
--- a/contrib/python/tornado/tornado-4/tornado/concurrent.py
+++ b/contrib/python/tornado/tornado-4/tornado/concurrent.py
@@ -1,521 +1,521 @@
-#!/usr/bin/env python
-#
-# Copyright 2012 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-"""Utilities for working with threads and ``Futures``.
-
-``Futures`` are a pattern for concurrent programming introduced in
-Python 3.2 in the `concurrent.futures` package. This package defines
-a mostly-compatible `Future` class designed for use from coroutines,
-as well as some utility functions for interacting with the
-`concurrent.futures` package.
-"""
-from __future__ import absolute_import, division, print_function
-
-import functools
-import platform
-import textwrap
-import traceback
-import sys
-
-from tornado.log import app_log
-from tornado.stack_context import ExceptionStackContext, wrap
-from tornado.util import raise_exc_info, ArgReplacer, is_finalizing
-
-try:
-    from concurrent import futures
-except ImportError:
-    futures = None
-
-try:
-    import typing
-except ImportError:
-    typing = None
-
-
-# Can the garbage collector handle cycles that include __del__ methods?
-# This is true in cpython beginning with version 3.4 (PEP 442).
-_GC_CYCLE_FINALIZERS = (platform.python_implementation() == 'CPython' and
-                        sys.version_info >= (3, 4))
-
-
-class ReturnValueIgnoredError(Exception):
-    pass
-
-# This class and associated code in the future object is derived
-# from the Trollius project, a backport of asyncio to Python 2.x - 3.x
-
-
-class _TracebackLogger(object):
-    """Helper to log a traceback upon destruction if not cleared.
-
-    This solves a nasty problem with Futures and Tasks that have an
-    exception set: if nobody asks for the exception, the exception is
-    never logged.  This violates the Zen of Python: 'Errors should
-    never pass silently.  Unless explicitly silenced.'
-
-    However, we don't want to log the exception as soon as
-    set_exception() is called: if the calling code is written
-    properly, it will get the exception and handle it properly.  But
-    we *do* want to log it if result() or exception() was never called
-    -- otherwise developers waste a lot of time wondering why their
-    buggy code fails silently.
-
-    An earlier attempt added a __del__() method to the Future class
-    itself, but this backfired because the presence of __del__()
-    prevents garbage collection from breaking cycles.  A way out of
-    this catch-22 is to avoid having a __del__() method on the Future
-    class itself, but instead to have a reference to a helper object
-    with a __del__() method that logs the traceback, where we ensure
-    that the helper object doesn't participate in cycles, and only the
-    Future has a reference to it.
-
-    The helper object is added when set_exception() is called.  When
-    the Future is collected, and the helper is present, the helper
-    object is also collected, and its __del__() method will log the
-    traceback.  When the Future's result() or exception() method is
-    called (and a helper object is present), it removes the the helper
-    object, after calling its clear() method to prevent it from
-    logging.
-
-    One downside is that we do a fair amount of work to extract the
-    traceback from the exception, even when it is never logged.  It
-    would seem cheaper to just store the exception object, but that
-    references the traceback, which references stack frames, which may
-    reference the Future, which references the _TracebackLogger, and
-    then the _TracebackLogger would be included in a cycle, which is
-    what we're trying to avoid!  As an optimization, we don't
-    immediately format the exception; we only do the work when
-    activate() is called, which call is delayed until after all the
-    Future's callbacks have run.  Since usually a Future has at least
-    one callback (typically set by 'yield From') and usually that
-    callback extracts the callback, thereby removing the need to
-    format the exception.
-
-    PS. I don't claim credit for this solution.  I first heard of it
-    in a discussion about closing files when they are collected.
-    """
-
-    __slots__ = ('exc_info', 'formatted_tb')
-
-    def __init__(self, exc_info):
-        self.exc_info = exc_info
-        self.formatted_tb = None
-
-    def activate(self):
-        exc_info = self.exc_info
-        if exc_info is not None:
-            self.exc_info = None
-            self.formatted_tb = traceback.format_exception(*exc_info)
-
-    def clear(self):
-        self.exc_info = None
-        self.formatted_tb = None
-
-    def __del__(self, is_finalizing=is_finalizing):
-        if not is_finalizing() and self.formatted_tb:
-            app_log.error('Future exception was never retrieved: %s',
-                          ''.join(self.formatted_tb).rstrip())
-
-
-class Future(object):
-    """Placeholder for an asynchronous result.
-
-    A ``Future`` encapsulates the result of an asynchronous
-    operation.  In synchronous applications ``Futures`` are used
-    to wait for the result from a thread or process pool; in
-    Tornado they are normally used with `.IOLoop.add_future` or by
-    yielding them in a `.gen.coroutine`.
-
-    `tornado.concurrent.Future` is similar to
-    `concurrent.futures.Future`, but not thread-safe (and therefore
-    faster for use with single-threaded event loops).
-
-    In addition to ``exception`` and ``set_exception``, methods ``exc_info``
-    and ``set_exc_info`` are supported to capture tracebacks in Python 2.
-    The traceback is automatically available in Python 3, but in the
-    Python 2 futures backport this information is discarded.
-    This functionality was previously available in a separate class
-    ``TracebackFuture``, which is now a deprecated alias for this class.
-
-    .. versionchanged:: 4.0
-       `tornado.concurrent.Future` is always a thread-unsafe ``Future``
-       with support for the ``exc_info`` methods.  Previously it would
-       be an alias for the thread-safe `concurrent.futures.Future`
-       if that package was available and fall back to the thread-unsafe
-       implementation if it was not.
-
-    .. versionchanged:: 4.1
-       If a `.Future` contains an error but that error is never observed
-       (by calling ``result()``, ``exception()``, or ``exc_info()``),
-       a stack trace will be logged when the `.Future` is garbage collected.
-       This normally indicates an error in the application, but in cases
-       where it results in undesired logging it may be necessary to
-       suppress the logging by ensuring that the exception is observed:
-       ``f.add_done_callback(lambda f: f.exception())``.
-    """
-    def __init__(self):
-        self._done = False
-        self._result = None
-        self._exc_info = None
-
-        self._log_traceback = False   # Used for Python >= 3.4
-        self._tb_logger = None        # Used for Python <= 3.3
-
-        self._callbacks = []
-
-    # Implement the Python 3.5 Awaitable protocol if possible
-    # (we can't use return and yield together until py33).
-    if sys.version_info >= (3, 3):
-        exec(textwrap.dedent("""
-        def __await__(self):
-            return (yield self)
-        """))
-    else:
-        # Py2-compatible version for use with cython.
-        def __await__(self):
-            result = yield self
-            # StopIteration doesn't take args before py33,
-            # but Cython recognizes the args tuple.
-            e = StopIteration()
-            e.args = (result,)
-            raise e
-
-    def cancel(self):
-        """Cancel the operation, if possible.
-
-        Tornado ``Futures`` do not support cancellation, so this method always
-        returns False.
-        """
-        return False
-
-    def cancelled(self):
-        """Returns True if the operation has been cancelled.
-
-        Tornado ``Futures`` do not support cancellation, so this method
-        always returns False.
-        """
-        return False
-
-    def running(self):
-        """Returns True if this operation is currently running."""
-        return not self._done
-
-    def done(self):
-        """Returns True if the future has finished running."""
-        return self._done
-
-    def _clear_tb_log(self):
-        self._log_traceback = False
-        if self._tb_logger is not None:
-            self._tb_logger.clear()
-            self._tb_logger = None
-
-    def result(self, timeout=None):
-        """If the operation succeeded, return its result.  If it failed,
-        re-raise its exception.
-
-        This method takes a ``timeout`` argument for compatibility with
-        `concurrent.futures.Future` but it is an error to call it
-        before the `Future` is done, so the ``timeout`` is never used.
-        """
-        self._clear_tb_log()
-        if self._result is not None:
-            return self._result
-        if self._exc_info is not None:
-            try:
-                raise_exc_info(self._exc_info)
-            finally:
-                self = None
-        self._check_done()
-        return self._result
-
-    def exception(self, timeout=None):
-        """If the operation raised an exception, return the `Exception`
-        object.  Otherwise returns None.
-
-        This method takes a ``timeout`` argument for compatibility with
-        `concurrent.futures.Future` but it is an error to call it
-        before the `Future` is done, so the ``timeout`` is never used.
-        """
-        self._clear_tb_log()
-        if self._exc_info is not None:
-            return self._exc_info[1]
-        else:
-            self._check_done()
-            return None
-
-    def add_done_callback(self, fn):
-        """Attaches the given callback to the `Future`.
-
-        It will be invoked with the `Future` as its argument when the Future
-        has finished running and its result is available.  In Tornado
-        consider using `.IOLoop.add_future` instead of calling
-        `add_done_callback` directly.
-        """
-        if self._done:
-            fn(self)
-        else:
-            self._callbacks.append(fn)
-
-    def set_result(self, result):
-        """Sets the result of a ``Future``.
-
-        It is undefined to call any of the ``set`` methods more than once
-        on the same object.
-        """
-        self._result = result
-        self._set_done()
-
-    def set_exception(self, exception):
-        """Sets the exception of a ``Future.``"""
-        self.set_exc_info(
-            (exception.__class__,
-             exception,
-             getattr(exception, '__traceback__', None)))
-
-    def exc_info(self):
-        """Returns a tuple in the same format as `sys.exc_info` or None.
-
-        .. versionadded:: 4.0
-        """
-        self._clear_tb_log()
-        return self._exc_info
-
-    def set_exc_info(self, exc_info):
-        """Sets the exception information of a ``Future.``
-
-        Preserves tracebacks on Python 2.
-
-        .. versionadded:: 4.0
-        """
-        self._exc_info = exc_info
-        self._log_traceback = True
-        if not _GC_CYCLE_FINALIZERS:
-            self._tb_logger = _TracebackLogger(exc_info)
-
-        try:
-            self._set_done()
-        finally:
-            # Activate the logger after all callbacks have had a
-            # chance to call result() or exception().
-            if self._log_traceback and self._tb_logger is not None:
-                self._tb_logger.activate()
-        self._exc_info = exc_info
-
-    def _check_done(self):
-        if not self._done:
-            raise Exception("DummyFuture does not support blocking for results")
-
-    def _set_done(self):
-        self._done = True
-        for cb in self._callbacks:
-            try:
-                cb(self)
-            except Exception:
-                app_log.exception('Exception in callback %r for %r',
-                                  cb, self)
-        self._callbacks = None
-
-    # On Python 3.3 or older, objects with a destructor part of a reference
-    # cycle are never destroyed. It's no longer the case on Python 3.4 thanks to
-    # the PEP 442.
-    if _GC_CYCLE_FINALIZERS:
-        def __del__(self, is_finalizing=is_finalizing):
-            if is_finalizing() or not self._log_traceback:
-                # set_exception() was not called, or result() or exception()
-                # has consumed the exception
-                return
-
-            tb = traceback.format_exception(*self._exc_info)
-
-            app_log.error('Future %r exception was never retrieved: %s',
-                          self, ''.join(tb).rstrip())
-
-
-TracebackFuture = Future
-
-if futures is None:
-    FUTURES = Future  # type: typing.Union[type, typing.Tuple[type, ...]]
-else:
-    FUTURES = (futures.Future, Future)
-
-
-def is_future(x):
-    return isinstance(x, FUTURES)
-
-
-class DummyExecutor(object):
-    def submit(self, fn, *args, **kwargs):
-        future = TracebackFuture()
-        try:
-            future.set_result(fn(*args, **kwargs))
-        except Exception:
-            future.set_exc_info(sys.exc_info())
-        return future
-
-    def shutdown(self, wait=True):
-        pass
-
-
-dummy_executor = DummyExecutor()
-
-
-def run_on_executor(*args, **kwargs):
-    """Decorator to run a synchronous method asynchronously on an executor.
-
-    The decorated method may be called with a ``callback`` keyword
-    argument and returns a future.
-
-    The `.IOLoop` and executor to be used are determined by the ``io_loop``
-    and ``executor`` attributes of ``self``. To use different attributes,
-    pass keyword arguments to the decorator::
-
-        @run_on_executor(executor='_thread_pool')
-        def foo(self):
-            pass
-
-    .. versionchanged:: 4.2
-       Added keyword arguments to use alternative attributes.
-    """
-    def run_on_executor_decorator(fn):
-        executor = kwargs.get("executor", "executor")
-        io_loop = kwargs.get("io_loop", "io_loop")
-
-        @functools.wraps(fn)
-        def wrapper(self, *args, **kwargs):
-            callback = kwargs.pop("callback", None)
-            future = getattr(self, executor).submit(fn, self, *args, **kwargs)
-            if callback:
-                getattr(self, io_loop).add_future(
-                    future, lambda future: callback(future.result()))
-            return future
-        return wrapper
-    if args and kwargs:
-        raise ValueError("cannot combine positional and keyword args")
-    if len(args) == 1:
-        return run_on_executor_decorator(args[0])
-    elif len(args) != 0:
-        raise ValueError("expected 1 argument, got %d", len(args))
-    return run_on_executor_decorator
-
-
-_NO_RESULT = object()
-
-
-def return_future(f):
-    """Decorator to make a function that returns via callback return a
-    `Future`.
-
-    The wrapped function should take a ``callback`` keyword argument
-    and invoke it with one argument when it has finished.  To signal failure,
-    the function can simply raise an exception (which will be
-    captured by the `.StackContext` and passed along to the ``Future``).
-
-    From the caller's perspective, the callback argument is optional.
-    If one is given, it will be invoked when the function is complete
-    with `Future.result()` as an argument.  If the function fails, the
-    callback will not be run and an exception will be raised into the
-    surrounding `.StackContext`.
-
-    If no callback is given, the caller should use the ``Future`` to
-    wait for the function to complete (perhaps by yielding it in a
-    `.gen.engine` function, or passing it to `.IOLoop.add_future`).
-
-    Usage:
-
-    .. testcode::
-
-        @return_future
-        def future_func(arg1, arg2, callback):
-            # Do stuff (possibly asynchronous)
-            callback(result)
-
-        @gen.engine
-        def caller(callback):
-            yield future_func(arg1, arg2)
-            callback()
-
-    ..
-
-    Note that ``@return_future`` and ``@gen.engine`` can be applied to the
-    same function, provided ``@return_future`` appears first.  However,
-    consider using ``@gen.coroutine`` instead of this combination.
-    """
-    replacer = ArgReplacer(f, 'callback')
-
-    @functools.wraps(f)
-    def wrapper(*args, **kwargs):
-        future = TracebackFuture()
-        callback, args, kwargs = replacer.replace(
-            lambda value=_NO_RESULT: future.set_result(value),
-            args, kwargs)
-
-        def handle_error(typ, value, tb):
-            future.set_exc_info((typ, value, tb))
-            return True
-        exc_info = None
-        with ExceptionStackContext(handle_error):
-            try:
-                result = f(*args, **kwargs)
-                if result is not None:
-                    raise ReturnValueIgnoredError(
-                        "@return_future should not be used with functions "
-                        "that return values")
-            except:
-                exc_info = sys.exc_info()
-                raise
-        if exc_info is not None:
-            # If the initial synchronous part of f() raised an exception,
-            # go ahead and raise it to the caller directly without waiting
-            # for them to inspect the Future.
-            future.result()
-
-        # If the caller passed in a callback, schedule it to be called
-        # when the future resolves.  It is important that this happens
-        # just before we return the future, or else we risk confusing
-        # stack contexts with multiple exceptions (one here with the
-        # immediate exception, and again when the future resolves and
-        # the callback triggers its exception by calling future.result()).
-        if callback is not None:
-            def run_callback(future):
-                result = future.result()
-                if result is _NO_RESULT:
-                    callback()
-                else:
-                    callback(future.result())
-            future.add_done_callback(wrap(run_callback))
-        return future
-    return wrapper
-
-
-def chain_future(a, b):
-    """Chain two futures together so that when one completes, so does the other.
-
-    The result (success or failure) of ``a`` will be copied to ``b``, unless
-    ``b`` has already been completed or cancelled by the time ``a`` finishes.
-    """
-    def copy(future):
-        assert future is a
-        if b.done():
-            return
-        if (isinstance(a, TracebackFuture) and
-                isinstance(b, TracebackFuture) and
-                a.exc_info() is not None):
-            b.set_exc_info(a.exc_info())
-        elif a.exception() is not None:
-            b.set_exception(a.exception())
-        else:
-            b.set_result(a.result())
-    a.add_done_callback(copy)
+#!/usr/bin/env python 
+# 
+# Copyright 2012 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+"""Utilities for working with threads and ``Futures``. 
+ 
+``Futures`` are a pattern for concurrent programming introduced in 
+Python 3.2 in the `concurrent.futures` package. This package defines 
+a mostly-compatible `Future` class designed for use from coroutines, 
+as well as some utility functions for interacting with the 
+`concurrent.futures` package. 
+""" 
+from __future__ import absolute_import, division, print_function 
+ 
+import functools 
+import platform 
+import textwrap 
+import traceback 
+import sys 
+ 
+from tornado.log import app_log 
+from tornado.stack_context import ExceptionStackContext, wrap 
+from tornado.util import raise_exc_info, ArgReplacer, is_finalizing 
+ 
+try: 
+    from concurrent import futures 
+except ImportError: 
+    futures = None 
+ 
+try: 
+    import typing 
+except ImportError: 
+    typing = None 
+ 
+ 
+# Can the garbage collector handle cycles that include __del__ methods? 
+# This is true in cpython beginning with version 3.4 (PEP 442). 
+_GC_CYCLE_FINALIZERS = (platform.python_implementation() == 'CPython' and 
+                        sys.version_info >= (3, 4)) 
+ 
+ 
+class ReturnValueIgnoredError(Exception): 
+    pass 
+ 
+# This class and associated code in the future object is derived 
+# from the Trollius project, a backport of asyncio to Python 2.x - 3.x 
+ 
+ 
+class _TracebackLogger(object): 
+    """Helper to log a traceback upon destruction if not cleared. 
+ 
+    This solves a nasty problem with Futures and Tasks that have an 
+    exception set: if nobody asks for the exception, the exception is 
+    never logged.  This violates the Zen of Python: 'Errors should 
+    never pass silently.  Unless explicitly silenced.' 
+ 
+    However, we don't want to log the exception as soon as 
+    set_exception() is called: if the calling code is written 
+    properly, it will get the exception and handle it properly.  But 
+    we *do* want to log it if result() or exception() was never called 
+    -- otherwise developers waste a lot of time wondering why their 
+    buggy code fails silently. 
+ 
+    An earlier attempt added a __del__() method to the Future class 
+    itself, but this backfired because the presence of __del__() 
+    prevents garbage collection from breaking cycles.  A way out of 
+    this catch-22 is to avoid having a __del__() method on the Future 
+    class itself, but instead to have a reference to a helper object 
+    with a __del__() method that logs the traceback, where we ensure 
+    that the helper object doesn't participate in cycles, and only the 
+    Future has a reference to it. 
+ 
+    The helper object is added when set_exception() is called.  When 
+    the Future is collected, and the helper is present, the helper 
+    object is also collected, and its __del__() method will log the 
+    traceback.  When the Future's result() or exception() method is 
+    called (and a helper object is present), it removes the the helper 
+    object, after calling its clear() method to prevent it from 
+    logging. 
+ 
+    One downside is that we do a fair amount of work to extract the 
+    traceback from the exception, even when it is never logged.  It 
+    would seem cheaper to just store the exception object, but that 
+    references the traceback, which references stack frames, which may 
+    reference the Future, which references the _TracebackLogger, and 
+    then the _TracebackLogger would be included in a cycle, which is 
+    what we're trying to avoid!  As an optimization, we don't 
+    immediately format the exception; we only do the work when 
+    activate() is called, which call is delayed until after all the 
+    Future's callbacks have run.  Since usually a Future has at least 
+    one callback (typically set by 'yield From') and usually that 
+    callback extracts the callback, thereby removing the need to 
+    format the exception. 
+ 
+    PS. I don't claim credit for this solution.  I first heard of it 
+    in a discussion about closing files when they are collected. 
+    """ 
+ 
+    __slots__ = ('exc_info', 'formatted_tb') 
+ 
+    def __init__(self, exc_info): 
+        self.exc_info = exc_info 
+        self.formatted_tb = None 
+ 
+    def activate(self): 
+        exc_info = self.exc_info 
+        if exc_info is not None: 
+            self.exc_info = None 
+            self.formatted_tb = traceback.format_exception(*exc_info) 
+ 
+    def clear(self): 
+        self.exc_info = None 
+        self.formatted_tb = None 
+ 
+    def __del__(self, is_finalizing=is_finalizing): 
+        if not is_finalizing() and self.formatted_tb: 
+            app_log.error('Future exception was never retrieved: %s', 
+                          ''.join(self.formatted_tb).rstrip()) 
+ 
+ 
+class Future(object): 
+    """Placeholder for an asynchronous result. 
+ 
+    A ``Future`` encapsulates the result of an asynchronous 
+    operation.  In synchronous applications ``Futures`` are used 
+    to wait for the result from a thread or process pool; in 
+    Tornado they are normally used with `.IOLoop.add_future` or by 
+    yielding them in a `.gen.coroutine`. 
+ 
+    `tornado.concurrent.Future` is similar to 
+    `concurrent.futures.Future`, but not thread-safe (and therefore 
+    faster for use with single-threaded event loops). 
+ 
+    In addition to ``exception`` and ``set_exception``, methods ``exc_info`` 
+    and ``set_exc_info`` are supported to capture tracebacks in Python 2. 
+    The traceback is automatically available in Python 3, but in the 
+    Python 2 futures backport this information is discarded. 
+    This functionality was previously available in a separate class 
+    ``TracebackFuture``, which is now a deprecated alias for this class. 
+ 
+    .. versionchanged:: 4.0 
+       `tornado.concurrent.Future` is always a thread-unsafe ``Future`` 
+       with support for the ``exc_info`` methods.  Previously it would 
+       be an alias for the thread-safe `concurrent.futures.Future` 
+       if that package was available and fall back to the thread-unsafe 
+       implementation if it was not. 
+ 
+    .. versionchanged:: 4.1 
+       If a `.Future` contains an error but that error is never observed 
+       (by calling ``result()``, ``exception()``, or ``exc_info()``), 
+       a stack trace will be logged when the `.Future` is garbage collected. 
+       This normally indicates an error in the application, but in cases 
+       where it results in undesired logging it may be necessary to 
+       suppress the logging by ensuring that the exception is observed: 
+       ``f.add_done_callback(lambda f: f.exception())``. 
+    """ 
+    def __init__(self): 
+        self._done = False 
+        self._result = None 
+        self._exc_info = None 
+ 
+        self._log_traceback = False   # Used for Python >= 3.4 
+        self._tb_logger = None        # Used for Python <= 3.3 
+ 
+        self._callbacks = [] 
+ 
+    # Implement the Python 3.5 Awaitable protocol if possible 
+    # (we can't use return and yield together until py33). 
+    if sys.version_info >= (3, 3): 
+        exec(textwrap.dedent(""" 
+        def __await__(self): 
+            return (yield self) 
+        """)) 
+    else: 
+        # Py2-compatible version for use with cython. 
+        def __await__(self): 
+            result = yield self 
+            # StopIteration doesn't take args before py33, 
+            # but Cython recognizes the args tuple. 
+            e = StopIteration() 
+            e.args = (result,) 
+            raise e 
+ 
+    def cancel(self): 
+        """Cancel the operation, if possible. 
+ 
+        Tornado ``Futures`` do not support cancellation, so this method always 
+        returns False. 
+        """ 
+        return False 
+ 
+    def cancelled(self): 
+        """Returns True if the operation has been cancelled. 
+ 
+        Tornado ``Futures`` do not support cancellation, so this method 
+        always returns False. 
+        """ 
+        return False 
+ 
+    def running(self): 
+        """Returns True if this operation is currently running.""" 
+        return not self._done 
+ 
+    def done(self): 
+        """Returns True if the future has finished running.""" 
+        return self._done 
+ 
+    def _clear_tb_log(self): 
+        self._log_traceback = False 
+        if self._tb_logger is not None: 
+            self._tb_logger.clear() 
+            self._tb_logger = None 
+ 
+    def result(self, timeout=None): 
+        """If the operation succeeded, return its result.  If it failed, 
+        re-raise its exception. 
+ 
+        This method takes a ``timeout`` argument for compatibility with 
+        `concurrent.futures.Future` but it is an error to call it 
+        before the `Future` is done, so the ``timeout`` is never used. 
+        """ 
+        self._clear_tb_log() 
+        if self._result is not None: 
+            return self._result 
+        if self._exc_info is not None: 
+            try: 
+                raise_exc_info(self._exc_info) 
+            finally: 
+                self = None 
+        self._check_done() 
+        return self._result 
+ 
+    def exception(self, timeout=None): 
+        """If the operation raised an exception, return the `Exception` 
+        object.  Otherwise returns None. 
+ 
+        This method takes a ``timeout`` argument for compatibility with 
+        `concurrent.futures.Future` but it is an error to call it 
+        before the `Future` is done, so the ``timeout`` is never used. 
+        """ 
+        self._clear_tb_log() 
+        if self._exc_info is not None: 
+            return self._exc_info[1] 
+        else: 
+            self._check_done() 
+            return None 
+ 
+    def add_done_callback(self, fn): 
+        """Attaches the given callback to the `Future`. 
+ 
+        It will be invoked with the `Future` as its argument when the Future 
+        has finished running and its result is available.  In Tornado 
+        consider using `.IOLoop.add_future` instead of calling 
+        `add_done_callback` directly. 
+        """ 
+        if self._done: 
+            fn(self) 
+        else: 
+            self._callbacks.append(fn) 
+ 
+    def set_result(self, result): 
+        """Sets the result of a ``Future``. 
+ 
+        It is undefined to call any of the ``set`` methods more than once 
+        on the same object. 
+        """ 
+        self._result = result 
+        self._set_done() 
+ 
+    def set_exception(self, exception): 
+        """Sets the exception of a ``Future.``""" 
+        self.set_exc_info( 
+            (exception.__class__, 
+             exception, 
+             getattr(exception, '__traceback__', None))) 
+ 
+    def exc_info(self): 
+        """Returns a tuple in the same format as `sys.exc_info` or None. 
+ 
+        .. versionadded:: 4.0 
+        """ 
+        self._clear_tb_log() 
+        return self._exc_info 
+ 
+    def set_exc_info(self, exc_info): 
+        """Sets the exception information of a ``Future.`` 
+ 
+        Preserves tracebacks on Python 2. 
+ 
+        .. versionadded:: 4.0 
+        """ 
+        self._exc_info = exc_info 
+        self._log_traceback = True 
+        if not _GC_CYCLE_FINALIZERS: 
+            self._tb_logger = _TracebackLogger(exc_info) 
+ 
+        try: 
+            self._set_done() 
+        finally: 
+            # Activate the logger after all callbacks have had a 
+            # chance to call result() or exception(). 
+            if self._log_traceback and self._tb_logger is not None: 
+                self._tb_logger.activate() 
+        self._exc_info = exc_info 
+ 
+    def _check_done(self): 
+        if not self._done: 
+            raise Exception("DummyFuture does not support blocking for results") 
+ 
+    def _set_done(self): 
+        self._done = True 
+        for cb in self._callbacks: 
+            try: 
+                cb(self) 
+            except Exception: 
+                app_log.exception('Exception in callback %r for %r', 
+                                  cb, self) 
+        self._callbacks = None 
+ 
+    # On Python 3.3 or older, objects with a destructor part of a reference 
+    # cycle are never destroyed. It's no longer the case on Python 3.4 thanks to 
+    # the PEP 442. 
+    if _GC_CYCLE_FINALIZERS: 
+        def __del__(self, is_finalizing=is_finalizing): 
+            if is_finalizing() or not self._log_traceback: 
+                # set_exception() was not called, or result() or exception() 
+                # has consumed the exception 
+                return 
+ 
+            tb = traceback.format_exception(*self._exc_info) 
+ 
+            app_log.error('Future %r exception was never retrieved: %s', 
+                          self, ''.join(tb).rstrip()) 
+ 
+ 
+TracebackFuture = Future 
+ 
+if futures is None: 
+    FUTURES = Future  # type: typing.Union[type, typing.Tuple[type, ...]] 
+else: 
+    FUTURES = (futures.Future, Future) 
+ 
+ 
+def is_future(x): 
+    return isinstance(x, FUTURES) 
+ 
+ 
+class DummyExecutor(object): 
+    def submit(self, fn, *args, **kwargs): 
+        future = TracebackFuture() 
+        try: 
+            future.set_result(fn(*args, **kwargs)) 
+        except Exception: 
+            future.set_exc_info(sys.exc_info()) 
+        return future 
+ 
+    def shutdown(self, wait=True): 
+        pass 
+ 
+ 
+dummy_executor = DummyExecutor() 
+ 
+ 
+def run_on_executor(*args, **kwargs): 
+    """Decorator to run a synchronous method asynchronously on an executor. 
+ 
+    The decorated method may be called with a ``callback`` keyword 
+    argument and returns a future. 
+ 
+    The `.IOLoop` and executor to be used are determined by the ``io_loop`` 
+    and ``executor`` attributes of ``self``. To use different attributes, 
+    pass keyword arguments to the decorator:: 
+ 
+        @run_on_executor(executor='_thread_pool') 
+        def foo(self): 
+            pass 
+ 
+    .. versionchanged:: 4.2 
+       Added keyword arguments to use alternative attributes. 
+    """ 
+    def run_on_executor_decorator(fn): 
+        executor = kwargs.get("executor", "executor") 
+        io_loop = kwargs.get("io_loop", "io_loop") 
+ 
+        @functools.wraps(fn) 
+        def wrapper(self, *args, **kwargs): 
+            callback = kwargs.pop("callback", None) 
+            future = getattr(self, executor).submit(fn, self, *args, **kwargs) 
+            if callback: 
+                getattr(self, io_loop).add_future( 
+                    future, lambda future: callback(future.result())) 
+            return future 
+        return wrapper 
+    if args and kwargs: 
+        raise ValueError("cannot combine positional and keyword args") 
+    if len(args) == 1: 
+        return run_on_executor_decorator(args[0]) 
+    elif len(args) != 0: 
+        raise ValueError("expected 1 argument, got %d", len(args)) 
+    return run_on_executor_decorator 
+ 
+ 
+_NO_RESULT = object() 
+ 
+ 
+def return_future(f): 
+    """Decorator to make a function that returns via callback return a 
+    `Future`. 
+ 
+    The wrapped function should take a ``callback`` keyword argument 
+    and invoke it with one argument when it has finished.  To signal failure, 
+    the function can simply raise an exception (which will be 
+    captured by the `.StackContext` and passed along to the ``Future``). 
+ 
+    From the caller's perspective, the callback argument is optional. 
+    If one is given, it will be invoked when the function is complete 
+    with `Future.result()` as an argument.  If the function fails, the 
+    callback will not be run and an exception will be raised into the 
+    surrounding `.StackContext`. 
+ 
+    If no callback is given, the caller should use the ``Future`` to 
+    wait for the function to complete (perhaps by yielding it in a 
+    `.gen.engine` function, or passing it to `.IOLoop.add_future`). 
+ 
+    Usage: 
+ 
+    .. testcode:: 
+ 
+        @return_future 
+        def future_func(arg1, arg2, callback): 
+            # Do stuff (possibly asynchronous) 
+            callback(result) 
+ 
+        @gen.engine 
+        def caller(callback): 
+            yield future_func(arg1, arg2) 
+            callback() 
+ 
+    .. 
+ 
+    Note that ``@return_future`` and ``@gen.engine`` can be applied to the 
+    same function, provided ``@return_future`` appears first.  However, 
+    consider using ``@gen.coroutine`` instead of this combination. 
+    """ 
+    replacer = ArgReplacer(f, 'callback') 
+ 
+    @functools.wraps(f) 
+    def wrapper(*args, **kwargs): 
+        future = TracebackFuture() 
+        callback, args, kwargs = replacer.replace( 
+            lambda value=_NO_RESULT: future.set_result(value), 
+            args, kwargs) 
+ 
+        def handle_error(typ, value, tb): 
+            future.set_exc_info((typ, value, tb)) 
+            return True 
+        exc_info = None 
+        with ExceptionStackContext(handle_error): 
+            try: 
+                result = f(*args, **kwargs) 
+                if result is not None: 
+                    raise ReturnValueIgnoredError( 
+                        "@return_future should not be used with functions " 
+                        "that return values") 
+            except: 
+                exc_info = sys.exc_info() 
+                raise 
+        if exc_info is not None: 
+            # If the initial synchronous part of f() raised an exception, 
+            # go ahead and raise it to the caller directly without waiting 
+            # for them to inspect the Future. 
+            future.result() 
+ 
+        # If the caller passed in a callback, schedule it to be called 
+        # when the future resolves.  It is important that this happens 
+        # just before we return the future, or else we risk confusing 
+        # stack contexts with multiple exceptions (one here with the 
+        # immediate exception, and again when the future resolves and 
+        # the callback triggers its exception by calling future.result()). 
+        if callback is not None: 
+            def run_callback(future): 
+                result = future.result() 
+                if result is _NO_RESULT: 
+                    callback() 
+                else: 
+                    callback(future.result()) 
+            future.add_done_callback(wrap(run_callback)) 
+        return future 
+    return wrapper 
+ 
+ 
+def chain_future(a, b): 
+    """Chain two futures together so that when one completes, so does the other. 
+ 
+    The result (success or failure) of ``a`` will be copied to ``b``, unless 
+    ``b`` has already been completed or cancelled by the time ``a`` finishes. 
+    """ 
+    def copy(future): 
+        assert future is a 
+        if b.done(): 
+            return 
+        if (isinstance(a, TracebackFuture) and 
+                isinstance(b, TracebackFuture) and 
+                a.exc_info() is not None): 
+            b.set_exc_info(a.exc_info()) 
+        elif a.exception() is not None: 
+            b.set_exception(a.exception()) 
+        else: 
+            b.set_result(a.result()) 
+    a.add_done_callback(copy) 
diff --git a/contrib/python/tornado/tornado-4/tornado/curl_httpclient.py b/contrib/python/tornado/tornado-4/tornado/curl_httpclient.py
index 28492c16cd..8632c788c1 100644
--- a/contrib/python/tornado/tornado-4/tornado/curl_httpclient.py
+++ b/contrib/python/tornado/tornado-4/tornado/curl_httpclient.py
@@ -1,524 +1,524 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Non-blocking HTTP client implementation using pycurl."""
-
-from __future__ import absolute_import, division, print_function
-
-import collections
-import functools
-import logging
-import pycurl  # type: ignore
-import threading
-import time
-from io import BytesIO
-
-from tornado import httputil
-from tornado import ioloop
-from tornado import stack_context
-
-from tornado.escape import utf8, native_str
-from tornado.httpclient import HTTPResponse, HTTPError, AsyncHTTPClient, main
-
-curl_log = logging.getLogger('tornado.curl_httpclient')
-
-
-class CurlAsyncHTTPClient(AsyncHTTPClient):
-    def initialize(self, io_loop, max_clients=10, defaults=None):
-        super(CurlAsyncHTTPClient, self).initialize(io_loop, defaults=defaults)
-        self._multi = pycurl.CurlMulti()
-        self._multi.setopt(pycurl.M_TIMERFUNCTION, self._set_timeout)
-        self._multi.setopt(pycurl.M_SOCKETFUNCTION, self._handle_socket)
-        self._curls = [self._curl_create() for i in range(max_clients)]
-        self._free_list = self._curls[:]
-        self._requests = collections.deque()
-        self._fds = {}
-        self._timeout = None
-
-        # libcurl has bugs that sometimes cause it to not report all
-        # relevant file descriptors and timeouts to TIMERFUNCTION/
-        # SOCKETFUNCTION.  Mitigate the effects of such bugs by
-        # forcing a periodic scan of all active requests.
-        self._force_timeout_callback = ioloop.PeriodicCallback(
-            self._handle_force_timeout, 1000, io_loop=io_loop)
-        self._force_timeout_callback.start()
-
-        # Work around a bug in libcurl 7.29.0: Some fields in the curl
-        # multi object are initialized lazily, and its destructor will
-        # segfault if it is destroyed without having been used.  Add
-        # and remove a dummy handle to make sure everything is
-        # initialized.
-        dummy_curl_handle = pycurl.Curl()
-        self._multi.add_handle(dummy_curl_handle)
-        self._multi.remove_handle(dummy_curl_handle)
-
-    def close(self):
-        self._force_timeout_callback.stop()
-        if self._timeout is not None:
-            self.io_loop.remove_timeout(self._timeout)
-        for curl in self._curls:
-            curl.close()
-        self._multi.close()
-        super(CurlAsyncHTTPClient, self).close()
-
-    def fetch_impl(self, request, callback):
-        self._requests.append((request, callback))
-        self._process_queue()
-        self._set_timeout(0)
-
-    def _handle_socket(self, event, fd, multi, data):
-        """Called by libcurl when it wants to change the file descriptors
-        it cares about.
-        """
-        event_map = {
-            pycurl.POLL_NONE: ioloop.IOLoop.NONE,
-            pycurl.POLL_IN: ioloop.IOLoop.READ,
-            pycurl.POLL_OUT: ioloop.IOLoop.WRITE,
-            pycurl.POLL_INOUT: ioloop.IOLoop.READ | ioloop.IOLoop.WRITE
-        }
-        if event == pycurl.POLL_REMOVE:
-            if fd in self._fds:
-                self.io_loop.remove_handler(fd)
-                del self._fds[fd]
-        else:
-            ioloop_event = event_map[event]
-            # libcurl sometimes closes a socket and then opens a new
-            # one using the same FD without giving us a POLL_NONE in
-            # between.  This is a problem with the epoll IOLoop,
-            # because the kernel can tell when a socket is closed and
-            # removes it from the epoll automatically, causing future
-            # update_handler calls to fail.  Since we can't tell when
-            # this has happened, always use remove and re-add
-            # instead of update.
-            if fd in self._fds:
-                self.io_loop.remove_handler(fd)
-            self.io_loop.add_handler(fd, self._handle_events,
-                                     ioloop_event)
-            self._fds[fd] = ioloop_event
-
-    def _set_timeout(self, msecs):
-        """Called by libcurl to schedule a timeout."""
-        if self._timeout is not None:
-            self.io_loop.remove_timeout(self._timeout)
-        self._timeout = self.io_loop.add_timeout(
-            self.io_loop.time() + msecs / 1000.0, self._handle_timeout)
-
-    def _handle_events(self, fd, events):
-        """Called by IOLoop when there is activity on one of our
-        file descriptors.
-        """
-        action = 0
-        if events & ioloop.IOLoop.READ:
-            action |= pycurl.CSELECT_IN
-        if events & ioloop.IOLoop.WRITE:
-            action |= pycurl.CSELECT_OUT
-        while True:
-            try:
-                ret, num_handles = self._multi.socket_action(fd, action)
-            except pycurl.error as e:
-                ret = e.args[0]
-            if ret != pycurl.E_CALL_MULTI_PERFORM:
-                break
-        self._finish_pending_requests()
-
-    def _handle_timeout(self):
-        """Called by IOLoop when the requested timeout has passed."""
-        with stack_context.NullContext():
-            self._timeout = None
-            while True:
-                try:
-                    ret, num_handles = self._multi.socket_action(
-                        pycurl.SOCKET_TIMEOUT, 0)
-                except pycurl.error as e:
-                    ret = e.args[0]
-                if ret != pycurl.E_CALL_MULTI_PERFORM:
-                    break
-            self._finish_pending_requests()
-
-        # In theory, we shouldn't have to do this because curl will
-        # call _set_timeout whenever the timeout changes.  However,
-        # sometimes after _handle_timeout we will need to reschedule
-        # immediately even though nothing has changed from curl's
-        # perspective.  This is because when socket_action is
-        # called with SOCKET_TIMEOUT, libcurl decides internally which
-        # timeouts need to be processed by using a monotonic clock
-        # (where available) while tornado uses python's time.time()
-        # to decide when timeouts have occurred.  When those clocks
-        # disagree on elapsed time (as they will whenever there is an
-        # NTP adjustment), tornado might call _handle_timeout before
-        # libcurl is ready.  After each timeout, resync the scheduled
-        # timeout with libcurl's current state.
-        new_timeout = self._multi.timeout()
-        if new_timeout >= 0:
-            self._set_timeout(new_timeout)
-
-    def _handle_force_timeout(self):
-        """Called by IOLoop periodically to ask libcurl to process any
-        events it may have forgotten about.
-        """
-        with stack_context.NullContext():
-            while True:
-                try:
-                    ret, num_handles = self._multi.socket_all()
-                except pycurl.error as e:
-                    ret = e.args[0]
-                if ret != pycurl.E_CALL_MULTI_PERFORM:
-                    break
-            self._finish_pending_requests()
-
-    def _finish_pending_requests(self):
-        """Process any requests that were completed by the last
-        call to multi.socket_action.
-        """
-        while True:
-            num_q, ok_list, err_list = self._multi.info_read()
-            for curl in ok_list:
-                self._finish(curl)
-            for curl, errnum, errmsg in err_list:
-                self._finish(curl, errnum, errmsg)
-            if num_q == 0:
-                break
-        self._process_queue()
-
-    def _process_queue(self):
-        with stack_context.NullContext():
-            while True:
-                started = 0
-                while self._free_list and self._requests:
-                    started += 1
-                    curl = self._free_list.pop()
-                    (request, callback) = self._requests.popleft()
-                    curl.info = {
-                        "headers": httputil.HTTPHeaders(),
-                        "buffer": BytesIO(),
-                        "request": request,
-                        "callback": callback,
-                        "curl_start_time": time.time(),
-                    }
-                    try:
-                        self._curl_setup_request(
-                            curl, request, curl.info["buffer"],
-                            curl.info["headers"])
-                    except Exception as e:
-                        # If there was an error in setup, pass it on
-                        # to the callback. Note that allowing the
-                        # error to escape here will appear to work
-                        # most of the time since we are still in the
-                        # caller's original stack frame, but when
-                        # _process_queue() is called from
-                        # _finish_pending_requests the exceptions have
-                        # nowhere to go.
-                        self._free_list.append(curl)
-                        callback(HTTPResponse(
-                            request=request,
-                            code=599,
-                            error=e))
-                    else:
-                        self._multi.add_handle(curl)
-
-                if not started:
-                    break
-
-    def _finish(self, curl, curl_error=None, curl_message=None):
-        info = curl.info
-        curl.info = None
-        self._multi.remove_handle(curl)
-        self._free_list.append(curl)
-        buffer = info["buffer"]
-        if curl_error:
-            error = CurlError(curl_error, curl_message)
-            code = error.code
-            effective_url = None
-            buffer.close()
-            buffer = None
-        else:
-            error = None
-            code = curl.getinfo(pycurl.HTTP_CODE)
-            effective_url = curl.getinfo(pycurl.EFFECTIVE_URL)
-            buffer.seek(0)
-        # the various curl timings are documented at
-        # http://curl.haxx.se/libcurl/c/curl_easy_getinfo.html
-        time_info = dict(
-            queue=info["curl_start_time"] - info["request"].start_time,
-            namelookup=curl.getinfo(pycurl.NAMELOOKUP_TIME),
-            connect=curl.getinfo(pycurl.CONNECT_TIME),
-            pretransfer=curl.getinfo(pycurl.PRETRANSFER_TIME),
-            starttransfer=curl.getinfo(pycurl.STARTTRANSFER_TIME),
-            total=curl.getinfo(pycurl.TOTAL_TIME),
-            redirect=curl.getinfo(pycurl.REDIRECT_TIME),
-        )
-        try:
-            info["callback"](HTTPResponse(
-                request=info["request"], code=code, headers=info["headers"],
-                buffer=buffer, effective_url=effective_url, error=error,
-                reason=info['headers'].get("X-Http-Reason", None),
-                request_time=time.time() - info["curl_start_time"],
-                time_info=time_info))
-        except Exception:
-            self.handle_callback_exception(info["callback"])
-
-    def handle_callback_exception(self, callback):
-        self.io_loop.handle_callback_exception(callback)
-
-    def _curl_create(self):
-        curl = pycurl.Curl()
-        if curl_log.isEnabledFor(logging.DEBUG):
-            curl.setopt(pycurl.VERBOSE, 1)
-            curl.setopt(pycurl.DEBUGFUNCTION, self._curl_debug)
-        if hasattr(pycurl, 'PROTOCOLS'):  # PROTOCOLS first appeared in pycurl 7.19.5 (2014-07-12)
-            curl.setopt(pycurl.PROTOCOLS, pycurl.PROTO_HTTP | pycurl.PROTO_HTTPS)
-            curl.setopt(pycurl.REDIR_PROTOCOLS, pycurl.PROTO_HTTP | pycurl.PROTO_HTTPS)
-        return curl
-
-    def _curl_setup_request(self, curl, request, buffer, headers):
-        curl.setopt(pycurl.URL, native_str(request.url))
-
-        # libcurl's magic "Expect: 100-continue" behavior causes delays
-        # with servers that don't support it (which include, among others,
-        # Google's OpenID endpoint).  Additionally, this behavior has
-        # a bug in conjunction with the curl_multi_socket_action API
-        # (https://sourceforge.net/tracker/?func=detail&atid=100976&aid=3039744&group_id=976),
-        # which increases the delays.  It's more trouble than it's worth,
-        # so just turn off the feature (yes, setting Expect: to an empty
-        # value is the official way to disable this)
-        if "Expect" not in request.headers:
-            request.headers["Expect"] = ""
-
-        # libcurl adds Pragma: no-cache by default; disable that too
-        if "Pragma" not in request.headers:
-            request.headers["Pragma"] = ""
-
-        curl.setopt(pycurl.HTTPHEADER,
-                    ["%s: %s" % (native_str(k), native_str(v))
-                     for k, v in request.headers.get_all()])
-
-        curl.setopt(pycurl.HEADERFUNCTION,
-                    functools.partial(self._curl_header_callback,
-                                      headers, request.header_callback))
-        if request.streaming_callback:
-            def write_function(chunk):
-                self.io_loop.add_callback(request.streaming_callback, chunk)
-        else:
-            write_function = buffer.write
-        if bytes is str:  # py2
-            curl.setopt(pycurl.WRITEFUNCTION, write_function)
-        else:  # py3
-            # Upstream pycurl doesn't support py3, but ubuntu 12.10 includes
-            # a fork/port.  That version has a bug in which it passes unicode
-            # strings instead of bytes to the WRITEFUNCTION.  This means that
-            # if you use a WRITEFUNCTION (which tornado always does), you cannot
-            # download arbitrary binary data.  This needs to be fixed in the
-            # ported pycurl package, but in the meantime this lambda will
-            # make it work for downloading (utf8) text.
-            curl.setopt(pycurl.WRITEFUNCTION, lambda s: write_function(utf8(s)))
-        curl.setopt(pycurl.FOLLOWLOCATION, request.follow_redirects)
-        curl.setopt(pycurl.MAXREDIRS, request.max_redirects)
-        curl.setopt(pycurl.CONNECTTIMEOUT_MS, int(1000 * request.connect_timeout))
-        curl.setopt(pycurl.TIMEOUT_MS, int(1000 * request.request_timeout))
-        if request.user_agent:
-            curl.setopt(pycurl.USERAGENT, native_str(request.user_agent))
-        else:
-            curl.setopt(pycurl.USERAGENT, "Mozilla/5.0 (compatible; pycurl)")
-        if request.network_interface:
-            curl.setopt(pycurl.INTERFACE, request.network_interface)
-        if request.decompress_response:
-            curl.setopt(pycurl.ENCODING, "gzip,deflate")
-        else:
-            curl.setopt(pycurl.ENCODING, "none")
-        if request.proxy_host and request.proxy_port:
-            curl.setopt(pycurl.PROXY, request.proxy_host)
-            curl.setopt(pycurl.PROXYPORT, request.proxy_port)
-            if request.proxy_username:
-                credentials = '%s:%s' % (request.proxy_username,
-                                         request.proxy_password)
-                curl.setopt(pycurl.PROXYUSERPWD, credentials)
-
-            if (request.proxy_auth_mode is None or
-                    request.proxy_auth_mode == "basic"):
-                curl.setopt(pycurl.PROXYAUTH, pycurl.HTTPAUTH_BASIC)
-            elif request.proxy_auth_mode == "digest":
-                curl.setopt(pycurl.PROXYAUTH, pycurl.HTTPAUTH_DIGEST)
-            else:
-                raise ValueError(
-                    "Unsupported proxy_auth_mode %s" % request.proxy_auth_mode)
-        else:
-            curl.setopt(pycurl.PROXY, '')
-            curl.unsetopt(pycurl.PROXYUSERPWD)
-        if request.validate_cert:
-            curl.setopt(pycurl.SSL_VERIFYPEER, 1)
-            curl.setopt(pycurl.SSL_VERIFYHOST, 2)
-        else:
-            curl.setopt(pycurl.SSL_VERIFYPEER, 0)
-            curl.setopt(pycurl.SSL_VERIFYHOST, 0)
-        if request.ca_certs is not None:
-            cafile, capath, cadata = None, None, None
-            if callable(request.ca_certs):
-                cafile, capath, cadata = request.ca_certs()
-            else:
-                cafile = request.ca_certs
-            if cafile is not None:
-                curl.setopt(pycurl.CAINFO, cafile)
-            if capath is not None:
-                curl.setopt(pycurl.CAPATH, capath)
-            if cadata is not None:
-                curl.set_ca_certs(cadata)
-        else:
-            # There is no way to restore pycurl.CAINFO to its default value
-            # (Using unsetopt makes it reject all certificates).
-            # I don't see any way to read the default value from python so it
-            # can be restored later.  We'll have to just leave CAINFO untouched
-            # if no ca_certs file was specified, and require that if any
-            # request uses a custom ca_certs file, they all must.
-            pass
-
-        if request.allow_ipv6 is False:
-            # Curl behaves reasonably when DNS resolution gives an ipv6 address
-            # that we can't reach, so allow ipv6 unless the user asks to disable.
-            curl.setopt(pycurl.IPRESOLVE, pycurl.IPRESOLVE_V4)
-        else:
-            curl.setopt(pycurl.IPRESOLVE, pycurl.IPRESOLVE_WHATEVER)
-
-        # Set the request method through curl's irritating interface which makes
-        # up names for almost every single method
-        curl_options = {
-            "GET": pycurl.HTTPGET,
-            "POST": pycurl.POST,
-            "PUT": pycurl.UPLOAD,
-            "HEAD": pycurl.NOBODY,
-        }
-        custom_methods = set(["DELETE", "OPTIONS", "PATCH"])
-        for o in curl_options.values():
-            curl.setopt(o, False)
-        if request.method in curl_options:
-            curl.unsetopt(pycurl.CUSTOMREQUEST)
-            curl.setopt(curl_options[request.method], True)
-        elif request.allow_nonstandard_methods or request.method in custom_methods:
-            curl.setopt(pycurl.CUSTOMREQUEST, request.method)
-        else:
-            raise KeyError('unknown method ' + request.method)
-
-        body_expected = request.method in ("POST", "PATCH", "PUT")
-        body_present = request.body is not None
-        if not request.allow_nonstandard_methods:
-            # Some HTTP methods nearly always have bodies while others
-            # almost never do. Fail in this case unless the user has
-            # opted out of sanity checks with allow_nonstandard_methods.
-            if ((body_expected and not body_present) or
-                    (body_present and not body_expected)):
-                raise ValueError(
-                    'Body must %sbe None for method %s (unless '
-                    'allow_nonstandard_methods is true)' %
-                    ('not ' if body_expected else '', request.method))
-
-        if body_expected or body_present:
-            if request.method == "GET":
-                # Even with `allow_nonstandard_methods` we disallow
-                # GET with a body (because libcurl doesn't allow it
-                # unless we use CUSTOMREQUEST). While the spec doesn't
-                # forbid clients from sending a body, it arguably
-                # disallows the server from doing anything with them.
-                raise ValueError('Body must be None for GET request')
-            request_buffer = BytesIO(utf8(request.body or ''))
-
-            def ioctl(cmd):
-                if cmd == curl.IOCMD_RESTARTREAD:
-                    request_buffer.seek(0)
-            curl.setopt(pycurl.READFUNCTION, request_buffer.read)
-            curl.setopt(pycurl.IOCTLFUNCTION, ioctl)
-            if request.method == "POST":
-                curl.setopt(pycurl.POSTFIELDSIZE, len(request.body or ''))
-            else:
-                curl.setopt(pycurl.UPLOAD, True)
-                curl.setopt(pycurl.INFILESIZE, len(request.body or ''))
-
-        if request.auth_username is not None:
-            userpwd = "%s:%s" % (request.auth_username, request.auth_password or '')
-
-            if request.auth_mode is None or request.auth_mode == "basic":
-                curl.setopt(pycurl.HTTPAUTH, pycurl.HTTPAUTH_BASIC)
-            elif request.auth_mode == "digest":
-                curl.setopt(pycurl.HTTPAUTH, pycurl.HTTPAUTH_DIGEST)
-            else:
-                raise ValueError("Unsupported auth_mode %s" % request.auth_mode)
-
-            curl.setopt(pycurl.USERPWD, native_str(userpwd))
-            curl_log.debug("%s %s (username: %r)", request.method, request.url,
-                           request.auth_username)
-        else:
-            curl.unsetopt(pycurl.USERPWD)
-            curl_log.debug("%s %s", request.method, request.url)
-
-        if request.client_cert is not None:
-            curl.setopt(pycurl.SSLCERT, request.client_cert)
-
-        if request.client_key is not None:
-            curl.setopt(pycurl.SSLKEY, request.client_key)
-
-        if request.ssl_options is not None:
-            raise ValueError("ssl_options not supported in curl_httpclient")
-
-        if threading.activeCount() > 1:
-            # libcurl/pycurl is not thread-safe by default.  When multiple threads
-            # are used, signals should be disabled.  This has the side effect
-            # of disabling DNS timeouts in some environments (when libcurl is
-            # not linked against ares), so we don't do it when there is only one
-            # thread.  Applications that use many short-lived threads may need
-            # to set NOSIGNAL manually in a prepare_curl_callback since
-            # there may not be any other threads running at the time we call
-            # threading.activeCount.
-            curl.setopt(pycurl.NOSIGNAL, 1)
-        if request.prepare_curl_callback is not None:
-            request.prepare_curl_callback(curl)
-
-    def _curl_header_callback(self, headers, header_callback, header_line):
-        header_line = native_str(header_line.decode('latin1'))
-        if header_callback is not None:
-            self.io_loop.add_callback(header_callback, header_line)
-        # header_line as returned by curl includes the end-of-line characters.
-        # whitespace at the start should be preserved to allow multi-line headers
-        header_line = header_line.rstrip()
-        if header_line.startswith("HTTP/"):
-            headers.clear()
-            try:
-                (__, __, reason) = httputil.parse_response_start_line(header_line)
-                header_line = "X-Http-Reason: %s" % reason
-            except httputil.HTTPInputError:
-                return
-        if not header_line:
-            return
-        headers.parse_line(header_line)
-
-    def _curl_debug(self, debug_type, debug_msg):
-        debug_types = ('I', '<', '>', '<', '>')
-        debug_msg = native_str(debug_msg)
-        if debug_type == 0:
-            curl_log.debug('%s', debug_msg.strip())
-        elif debug_type in (1, 2):
-            for line in debug_msg.splitlines():
-                curl_log.debug('%s %s', debug_types[debug_type], line)
-        elif debug_type == 4:
-            curl_log.debug('%s %r', debug_types[debug_type], debug_msg)
-
-
-class CurlError(HTTPError):
-    def __init__(self, errno, message):
-        HTTPError.__init__(self, 599, message)
-        self.errno = errno
-
-
-if __name__ == "__main__":
-    AsyncHTTPClient.configure(CurlAsyncHTTPClient)
-    main()
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Non-blocking HTTP client implementation using pycurl.""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import collections 
+import functools 
+import logging 
+import pycurl  # type: ignore 
+import threading 
+import time 
+from io import BytesIO 
+ 
+from tornado import httputil 
+from tornado import ioloop 
+from tornado import stack_context 
+ 
+from tornado.escape import utf8, native_str 
+from tornado.httpclient import HTTPResponse, HTTPError, AsyncHTTPClient, main 
+ 
+curl_log = logging.getLogger('tornado.curl_httpclient') 
+ 
+ 
+class CurlAsyncHTTPClient(AsyncHTTPClient): 
+    def initialize(self, io_loop, max_clients=10, defaults=None): 
+        super(CurlAsyncHTTPClient, self).initialize(io_loop, defaults=defaults) 
+        self._multi = pycurl.CurlMulti() 
+        self._multi.setopt(pycurl.M_TIMERFUNCTION, self._set_timeout) 
+        self._multi.setopt(pycurl.M_SOCKETFUNCTION, self._handle_socket) 
+        self._curls = [self._curl_create() for i in range(max_clients)] 
+        self._free_list = self._curls[:] 
+        self._requests = collections.deque() 
+        self._fds = {} 
+        self._timeout = None 
+ 
+        # libcurl has bugs that sometimes cause it to not report all 
+        # relevant file descriptors and timeouts to TIMERFUNCTION/ 
+        # SOCKETFUNCTION.  Mitigate the effects of such bugs by 
+        # forcing a periodic scan of all active requests. 
+        self._force_timeout_callback = ioloop.PeriodicCallback( 
+            self._handle_force_timeout, 1000, io_loop=io_loop) 
+        self._force_timeout_callback.start() 
+ 
+        # Work around a bug in libcurl 7.29.0: Some fields in the curl 
+        # multi object are initialized lazily, and its destructor will 
+        # segfault if it is destroyed without having been used.  Add 
+        # and remove a dummy handle to make sure everything is 
+        # initialized. 
+        dummy_curl_handle = pycurl.Curl() 
+        self._multi.add_handle(dummy_curl_handle) 
+        self._multi.remove_handle(dummy_curl_handle) 
+ 
+    def close(self): 
+        self._force_timeout_callback.stop() 
+        if self._timeout is not None: 
+            self.io_loop.remove_timeout(self._timeout) 
+        for curl in self._curls: 
+            curl.close() 
+        self._multi.close() 
+        super(CurlAsyncHTTPClient, self).close() 
+ 
+    def fetch_impl(self, request, callback): 
+        self._requests.append((request, callback)) 
+        self._process_queue() 
+        self._set_timeout(0) 
+ 
+    def _handle_socket(self, event, fd, multi, data): 
+        """Called by libcurl when it wants to change the file descriptors 
+        it cares about. 
+        """ 
+        event_map = { 
+            pycurl.POLL_NONE: ioloop.IOLoop.NONE, 
+            pycurl.POLL_IN: ioloop.IOLoop.READ, 
+            pycurl.POLL_OUT: ioloop.IOLoop.WRITE, 
+            pycurl.POLL_INOUT: ioloop.IOLoop.READ | ioloop.IOLoop.WRITE 
+        } 
+        if event == pycurl.POLL_REMOVE: 
+            if fd in self._fds: 
+                self.io_loop.remove_handler(fd) 
+                del self._fds[fd] 
+        else: 
+            ioloop_event = event_map[event] 
+            # libcurl sometimes closes a socket and then opens a new 
+            # one using the same FD without giving us a POLL_NONE in 
+            # between.  This is a problem with the epoll IOLoop, 
+            # because the kernel can tell when a socket is closed and 
+            # removes it from the epoll automatically, causing future 
+            # update_handler calls to fail.  Since we can't tell when 
+            # this has happened, always use remove and re-add 
+            # instead of update. 
+            if fd in self._fds: 
+                self.io_loop.remove_handler(fd) 
+            self.io_loop.add_handler(fd, self._handle_events, 
+                                     ioloop_event) 
+            self._fds[fd] = ioloop_event 
+ 
+    def _set_timeout(self, msecs): 
+        """Called by libcurl to schedule a timeout.""" 
+        if self._timeout is not None: 
+            self.io_loop.remove_timeout(self._timeout) 
+        self._timeout = self.io_loop.add_timeout( 
+            self.io_loop.time() + msecs / 1000.0, self._handle_timeout) 
+ 
+    def _handle_events(self, fd, events): 
+        """Called by IOLoop when there is activity on one of our 
+        file descriptors. 
+        """ 
+        action = 0 
+        if events & ioloop.IOLoop.READ: 
+            action |= pycurl.CSELECT_IN 
+        if events & ioloop.IOLoop.WRITE: 
+            action |= pycurl.CSELECT_OUT 
+        while True: 
+            try: 
+                ret, num_handles = self._multi.socket_action(fd, action) 
+            except pycurl.error as e: 
+                ret = e.args[0] 
+            if ret != pycurl.E_CALL_MULTI_PERFORM: 
+                break 
+        self._finish_pending_requests() 
+ 
+    def _handle_timeout(self): 
+        """Called by IOLoop when the requested timeout has passed.""" 
+        with stack_context.NullContext(): 
+            self._timeout = None 
+            while True: 
+                try: 
+                    ret, num_handles = self._multi.socket_action( 
+                        pycurl.SOCKET_TIMEOUT, 0) 
+                except pycurl.error as e: 
+                    ret = e.args[0] 
+                if ret != pycurl.E_CALL_MULTI_PERFORM: 
+                    break 
+            self._finish_pending_requests() 
+ 
+        # In theory, we shouldn't have to do this because curl will 
+        # call _set_timeout whenever the timeout changes.  However, 
+        # sometimes after _handle_timeout we will need to reschedule 
+        # immediately even though nothing has changed from curl's 
+        # perspective.  This is because when socket_action is 
+        # called with SOCKET_TIMEOUT, libcurl decides internally which 
+        # timeouts need to be processed by using a monotonic clock 
+        # (where available) while tornado uses python's time.time() 
+        # to decide when timeouts have occurred.  When those clocks 
+        # disagree on elapsed time (as they will whenever there is an 
+        # NTP adjustment), tornado might call _handle_timeout before 
+        # libcurl is ready.  After each timeout, resync the scheduled 
+        # timeout with libcurl's current state. 
+        new_timeout = self._multi.timeout() 
+        if new_timeout >= 0: 
+            self._set_timeout(new_timeout) 
+ 
+    def _handle_force_timeout(self): 
+        """Called by IOLoop periodically to ask libcurl to process any 
+        events it may have forgotten about. 
+        """ 
+        with stack_context.NullContext(): 
+            while True: 
+                try: 
+                    ret, num_handles = self._multi.socket_all() 
+                except pycurl.error as e: 
+                    ret = e.args[0] 
+                if ret != pycurl.E_CALL_MULTI_PERFORM: 
+                    break 
+            self._finish_pending_requests() 
+ 
+    def _finish_pending_requests(self): 
+        """Process any requests that were completed by the last 
+        call to multi.socket_action. 
+        """ 
+        while True: 
+            num_q, ok_list, err_list = self._multi.info_read() 
+            for curl in ok_list: 
+                self._finish(curl) 
+            for curl, errnum, errmsg in err_list: 
+                self._finish(curl, errnum, errmsg) 
+            if num_q == 0: 
+                break 
+        self._process_queue() 
+ 
+    def _process_queue(self): 
+        with stack_context.NullContext(): 
+            while True: 
+                started = 0 
+                while self._free_list and self._requests: 
+                    started += 1 
+                    curl = self._free_list.pop() 
+                    (request, callback) = self._requests.popleft() 
+                    curl.info = { 
+                        "headers": httputil.HTTPHeaders(), 
+                        "buffer": BytesIO(), 
+                        "request": request, 
+                        "callback": callback, 
+                        "curl_start_time": time.time(), 
+                    } 
+                    try: 
+                        self._curl_setup_request( 
+                            curl, request, curl.info["buffer"], 
+                            curl.info["headers"]) 
+                    except Exception as e: 
+                        # If there was an error in setup, pass it on 
+                        # to the callback. Note that allowing the 
+                        # error to escape here will appear to work 
+                        # most of the time since we are still in the 
+                        # caller's original stack frame, but when 
+                        # _process_queue() is called from 
+                        # _finish_pending_requests the exceptions have 
+                        # nowhere to go. 
+                        self._free_list.append(curl) 
+                        callback(HTTPResponse( 
+                            request=request, 
+                            code=599, 
+                            error=e)) 
+                    else: 
+                        self._multi.add_handle(curl) 
+ 
+                if not started: 
+                    break 
+ 
+    def _finish(self, curl, curl_error=None, curl_message=None): 
+        info = curl.info 
+        curl.info = None 
+        self._multi.remove_handle(curl) 
+        self._free_list.append(curl) 
+        buffer = info["buffer"] 
+        if curl_error: 
+            error = CurlError(curl_error, curl_message) 
+            code = error.code 
+            effective_url = None 
+            buffer.close() 
+            buffer = None 
+        else: 
+            error = None 
+            code = curl.getinfo(pycurl.HTTP_CODE) 
+            effective_url = curl.getinfo(pycurl.EFFECTIVE_URL) 
+            buffer.seek(0) 
+        # the various curl timings are documented at 
+        # http://curl.haxx.se/libcurl/c/curl_easy_getinfo.html 
+        time_info = dict( 
+            queue=info["curl_start_time"] - info["request"].start_time, 
+            namelookup=curl.getinfo(pycurl.NAMELOOKUP_TIME), 
+            connect=curl.getinfo(pycurl.CONNECT_TIME), 
+            pretransfer=curl.getinfo(pycurl.PRETRANSFER_TIME), 
+            starttransfer=curl.getinfo(pycurl.STARTTRANSFER_TIME), 
+            total=curl.getinfo(pycurl.TOTAL_TIME), 
+            redirect=curl.getinfo(pycurl.REDIRECT_TIME), 
+        ) 
+        try: 
+            info["callback"](HTTPResponse( 
+                request=info["request"], code=code, headers=info["headers"], 
+                buffer=buffer, effective_url=effective_url, error=error, 
+                reason=info['headers'].get("X-Http-Reason", None), 
+                request_time=time.time() - info["curl_start_time"], 
+                time_info=time_info)) 
+        except Exception: 
+            self.handle_callback_exception(info["callback"]) 
+ 
+    def handle_callback_exception(self, callback): 
+        self.io_loop.handle_callback_exception(callback) 
+ 
+    def _curl_create(self): 
+        curl = pycurl.Curl() 
+        if curl_log.isEnabledFor(logging.DEBUG): 
+            curl.setopt(pycurl.VERBOSE, 1) 
+            curl.setopt(pycurl.DEBUGFUNCTION, self._curl_debug) 
+        if hasattr(pycurl, 'PROTOCOLS'):  # PROTOCOLS first appeared in pycurl 7.19.5 (2014-07-12) 
+            curl.setopt(pycurl.PROTOCOLS, pycurl.PROTO_HTTP | pycurl.PROTO_HTTPS) 
+            curl.setopt(pycurl.REDIR_PROTOCOLS, pycurl.PROTO_HTTP | pycurl.PROTO_HTTPS) 
+        return curl 
+ 
+    def _curl_setup_request(self, curl, request, buffer, headers): 
+        curl.setopt(pycurl.URL, native_str(request.url)) 
+ 
+        # libcurl's magic "Expect: 100-continue" behavior causes delays 
+        # with servers that don't support it (which include, among others, 
+        # Google's OpenID endpoint).  Additionally, this behavior has 
+        # a bug in conjunction with the curl_multi_socket_action API 
+        # (https://sourceforge.net/tracker/?func=detail&atid=100976&aid=3039744&group_id=976), 
+        # which increases the delays.  It's more trouble than it's worth, 
+        # so just turn off the feature (yes, setting Expect: to an empty 
+        # value is the official way to disable this) 
+        if "Expect" not in request.headers: 
+            request.headers["Expect"] = "" 
+ 
+        # libcurl adds Pragma: no-cache by default; disable that too 
+        if "Pragma" not in request.headers: 
+            request.headers["Pragma"] = "" 
+ 
+        curl.setopt(pycurl.HTTPHEADER, 
+                    ["%s: %s" % (native_str(k), native_str(v)) 
+                     for k, v in request.headers.get_all()]) 
+ 
+        curl.setopt(pycurl.HEADERFUNCTION, 
+                    functools.partial(self._curl_header_callback, 
+                                      headers, request.header_callback)) 
+        if request.streaming_callback: 
+            def write_function(chunk): 
+                self.io_loop.add_callback(request.streaming_callback, chunk) 
+        else: 
+            write_function = buffer.write 
+        if bytes is str:  # py2 
+            curl.setopt(pycurl.WRITEFUNCTION, write_function) 
+        else:  # py3 
+            # Upstream pycurl doesn't support py3, but ubuntu 12.10 includes 
+            # a fork/port.  That version has a bug in which it passes unicode 
+            # strings instead of bytes to the WRITEFUNCTION.  This means that 
+            # if you use a WRITEFUNCTION (which tornado always does), you cannot 
+            # download arbitrary binary data.  This needs to be fixed in the 
+            # ported pycurl package, but in the meantime this lambda will 
+            # make it work for downloading (utf8) text. 
+            curl.setopt(pycurl.WRITEFUNCTION, lambda s: write_function(utf8(s))) 
+        curl.setopt(pycurl.FOLLOWLOCATION, request.follow_redirects) 
+        curl.setopt(pycurl.MAXREDIRS, request.max_redirects) 
+        curl.setopt(pycurl.CONNECTTIMEOUT_MS, int(1000 * request.connect_timeout)) 
+        curl.setopt(pycurl.TIMEOUT_MS, int(1000 * request.request_timeout)) 
+        if request.user_agent: 
+            curl.setopt(pycurl.USERAGENT, native_str(request.user_agent)) 
+        else: 
+            curl.setopt(pycurl.USERAGENT, "Mozilla/5.0 (compatible; pycurl)") 
+        if request.network_interface: 
+            curl.setopt(pycurl.INTERFACE, request.network_interface) 
+        if request.decompress_response: 
+            curl.setopt(pycurl.ENCODING, "gzip,deflate") 
+        else: 
+            curl.setopt(pycurl.ENCODING, "none") 
+        if request.proxy_host and request.proxy_port: 
+            curl.setopt(pycurl.PROXY, request.proxy_host) 
+            curl.setopt(pycurl.PROXYPORT, request.proxy_port) 
+            if request.proxy_username: 
+                credentials = '%s:%s' % (request.proxy_username, 
+                                         request.proxy_password) 
+                curl.setopt(pycurl.PROXYUSERPWD, credentials) 
+ 
+            if (request.proxy_auth_mode is None or 
+                    request.proxy_auth_mode == "basic"): 
+                curl.setopt(pycurl.PROXYAUTH, pycurl.HTTPAUTH_BASIC) 
+            elif request.proxy_auth_mode == "digest": 
+                curl.setopt(pycurl.PROXYAUTH, pycurl.HTTPAUTH_DIGEST) 
+            else: 
+                raise ValueError( 
+                    "Unsupported proxy_auth_mode %s" % request.proxy_auth_mode) 
+        else: 
+            curl.setopt(pycurl.PROXY, '') 
+            curl.unsetopt(pycurl.PROXYUSERPWD) 
+        if request.validate_cert: 
+            curl.setopt(pycurl.SSL_VERIFYPEER, 1) 
+            curl.setopt(pycurl.SSL_VERIFYHOST, 2) 
+        else: 
+            curl.setopt(pycurl.SSL_VERIFYPEER, 0) 
+            curl.setopt(pycurl.SSL_VERIFYHOST, 0) 
+        if request.ca_certs is not None: 
+            cafile, capath, cadata = None, None, None 
+            if callable(request.ca_certs): 
+                cafile, capath, cadata = request.ca_certs() 
+            else: 
+                cafile = request.ca_certs 
+            if cafile is not None: 
+                curl.setopt(pycurl.CAINFO, cafile) 
+            if capath is not None: 
+                curl.setopt(pycurl.CAPATH, capath) 
+            if cadata is not None: 
+                curl.set_ca_certs(cadata) 
+        else: 
+            # There is no way to restore pycurl.CAINFO to its default value 
+            # (Using unsetopt makes it reject all certificates). 
+            # I don't see any way to read the default value from python so it 
+            # can be restored later.  We'll have to just leave CAINFO untouched 
+            # if no ca_certs file was specified, and require that if any 
+            # request uses a custom ca_certs file, they all must. 
+            pass 
+ 
+        if request.allow_ipv6 is False: 
+            # Curl behaves reasonably when DNS resolution gives an ipv6 address 
+            # that we can't reach, so allow ipv6 unless the user asks to disable. 
+            curl.setopt(pycurl.IPRESOLVE, pycurl.IPRESOLVE_V4) 
+        else: 
+            curl.setopt(pycurl.IPRESOLVE, pycurl.IPRESOLVE_WHATEVER) 
+ 
+        # Set the request method through curl's irritating interface which makes 
+        # up names for almost every single method 
+        curl_options = { 
+            "GET": pycurl.HTTPGET, 
+            "POST": pycurl.POST, 
+            "PUT": pycurl.UPLOAD, 
+            "HEAD": pycurl.NOBODY, 
+        } 
+        custom_methods = set(["DELETE", "OPTIONS", "PATCH"]) 
+        for o in curl_options.values(): 
+            curl.setopt(o, False) 
+        if request.method in curl_options: 
+            curl.unsetopt(pycurl.CUSTOMREQUEST) 
+            curl.setopt(curl_options[request.method], True) 
+        elif request.allow_nonstandard_methods or request.method in custom_methods: 
+            curl.setopt(pycurl.CUSTOMREQUEST, request.method) 
+        else: 
+            raise KeyError('unknown method ' + request.method) 
+ 
+        body_expected = request.method in ("POST", "PATCH", "PUT") 
+        body_present = request.body is not None 
+        if not request.allow_nonstandard_methods: 
+            # Some HTTP methods nearly always have bodies while others 
+            # almost never do. Fail in this case unless the user has 
+            # opted out of sanity checks with allow_nonstandard_methods. 
+            if ((body_expected and not body_present) or 
+                    (body_present and not body_expected)): 
+                raise ValueError( 
+                    'Body must %sbe None for method %s (unless ' 
+                    'allow_nonstandard_methods is true)' % 
+                    ('not ' if body_expected else '', request.method)) 
+ 
+        if body_expected or body_present: 
+            if request.method == "GET": 
+                # Even with `allow_nonstandard_methods` we disallow 
+                # GET with a body (because libcurl doesn't allow it 
+                # unless we use CUSTOMREQUEST). While the spec doesn't 
+                # forbid clients from sending a body, it arguably 
+                # disallows the server from doing anything with them. 
+                raise ValueError('Body must be None for GET request') 
+            request_buffer = BytesIO(utf8(request.body or '')) 
+ 
+            def ioctl(cmd): 
+                if cmd == curl.IOCMD_RESTARTREAD: 
+                    request_buffer.seek(0) 
+            curl.setopt(pycurl.READFUNCTION, request_buffer.read) 
+            curl.setopt(pycurl.IOCTLFUNCTION, ioctl) 
+            if request.method == "POST": 
+                curl.setopt(pycurl.POSTFIELDSIZE, len(request.body or '')) 
+            else: 
+                curl.setopt(pycurl.UPLOAD, True) 
+                curl.setopt(pycurl.INFILESIZE, len(request.body or '')) 
+ 
+        if request.auth_username is not None: 
+            userpwd = "%s:%s" % (request.auth_username, request.auth_password or '') 
+ 
+            if request.auth_mode is None or request.auth_mode == "basic": 
+                curl.setopt(pycurl.HTTPAUTH, pycurl.HTTPAUTH_BASIC) 
+            elif request.auth_mode == "digest": 
+                curl.setopt(pycurl.HTTPAUTH, pycurl.HTTPAUTH_DIGEST) 
+            else: 
+                raise ValueError("Unsupported auth_mode %s" % request.auth_mode) 
+ 
+            curl.setopt(pycurl.USERPWD, native_str(userpwd)) 
+            curl_log.debug("%s %s (username: %r)", request.method, request.url, 
+                           request.auth_username) 
+        else: 
+            curl.unsetopt(pycurl.USERPWD) 
+            curl_log.debug("%s %s", request.method, request.url) 
+ 
+        if request.client_cert is not None: 
+            curl.setopt(pycurl.SSLCERT, request.client_cert) 
+ 
+        if request.client_key is not None: 
+            curl.setopt(pycurl.SSLKEY, request.client_key) 
+ 
+        if request.ssl_options is not None: 
+            raise ValueError("ssl_options not supported in curl_httpclient") 
+ 
+        if threading.activeCount() > 1: 
+            # libcurl/pycurl is not thread-safe by default.  When multiple threads 
+            # are used, signals should be disabled.  This has the side effect 
+            # of disabling DNS timeouts in some environments (when libcurl is 
+            # not linked against ares), so we don't do it when there is only one 
+            # thread.  Applications that use many short-lived threads may need 
+            # to set NOSIGNAL manually in a prepare_curl_callback since 
+            # there may not be any other threads running at the time we call 
+            # threading.activeCount. 
+            curl.setopt(pycurl.NOSIGNAL, 1) 
+        if request.prepare_curl_callback is not None: 
+            request.prepare_curl_callback(curl) 
+ 
+    def _curl_header_callback(self, headers, header_callback, header_line): 
+        header_line = native_str(header_line.decode('latin1')) 
+        if header_callback is not None: 
+            self.io_loop.add_callback(header_callback, header_line) 
+        # header_line as returned by curl includes the end-of-line characters. 
+        # whitespace at the start should be preserved to allow multi-line headers 
+        header_line = header_line.rstrip() 
+        if header_line.startswith("HTTP/"): 
+            headers.clear() 
+            try: 
+                (__, __, reason) = httputil.parse_response_start_line(header_line) 
+                header_line = "X-Http-Reason: %s" % reason 
+            except httputil.HTTPInputError: 
+                return 
+        if not header_line: 
+            return 
+        headers.parse_line(header_line) 
+ 
+    def _curl_debug(self, debug_type, debug_msg): 
+        debug_types = ('I', '<', '>', '<', '>') 
+        debug_msg = native_str(debug_msg) 
+        if debug_type == 0: 
+            curl_log.debug('%s', debug_msg.strip()) 
+        elif debug_type in (1, 2): 
+            for line in debug_msg.splitlines(): 
+                curl_log.debug('%s %s', debug_types[debug_type], line) 
+        elif debug_type == 4: 
+            curl_log.debug('%s %r', debug_types[debug_type], debug_msg) 
+ 
+ 
+class CurlError(HTTPError): 
+    def __init__(self, errno, message): 
+        HTTPError.__init__(self, 599, message) 
+        self.errno = errno 
+ 
+ 
+if __name__ == "__main__": 
+    AsyncHTTPClient.configure(CurlAsyncHTTPClient) 
+    main() 
diff --git a/contrib/python/tornado/tornado-4/tornado/escape.py b/contrib/python/tornado/tornado-4/tornado/escape.py
index 2ca3fe3fe8..0fc63f8d20 100644
--- a/contrib/python/tornado/tornado-4/tornado/escape.py
+++ b/contrib/python/tornado/tornado-4/tornado/escape.py
@@ -1,398 +1,398 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Escaping/unescaping methods for HTML, JSON, URLs, and others.
-
-Also includes a few other miscellaneous string manipulation functions that
-have crept in over time.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import json
-import re
-
-from tornado.util import PY3, unicode_type, basestring_type
-
-if PY3:
-    from urllib.parse import parse_qs as _parse_qs
-    import html.entities as htmlentitydefs
-    import urllib.parse as urllib_parse
-    unichr = chr
-else:
-    from urlparse import parse_qs as _parse_qs
-    import htmlentitydefs
-    import urllib as urllib_parse
-
-try:
-    import typing  # noqa
-except ImportError:
-    pass
-
-
-_XHTML_ESCAPE_RE = re.compile('[&<>"\']')
-_XHTML_ESCAPE_DICT = {'&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;',
-                      '\'': '&#39;'}
-
-
-def xhtml_escape(value):
-    """Escapes a string so it is valid within HTML or XML.
-
-    Escapes the characters ``<``, ``>``, ``"``, ``'``, and ``&``.
-    When used in attribute values the escaped strings must be enclosed
-    in quotes.
-
-    .. versionchanged:: 3.2
-
-       Added the single quote to the list of escaped characters.
-    """
-    return _XHTML_ESCAPE_RE.sub(lambda match: _XHTML_ESCAPE_DICT[match.group(0)],
-                                to_basestring(value))
-
-
-def xhtml_unescape(value):
-    """Un-escapes an XML-escaped string."""
-    return re.sub(r"&(#?)(\w+?);", _convert_entity, _unicode(value))
-
-
-# The fact that json_encode wraps json.dumps is an implementation detail.
-# Please see https://github.com/tornadoweb/tornado/pull/706
-# before sending a pull request that adds **kwargs to this function.
-def json_encode(value):
-    """JSON-encodes the given Python object."""
-    # JSON permits but does not require forward slashes to be escaped.
-    # This is useful when json data is emitted in a <script> tag
-    # in HTML, as it prevents </script> tags from prematurely terminating
-    # the javascript.  Some json libraries do this escaping by default,
-    # although python's standard library does not, so we do it here.
-    # http://stackoverflow.com/questions/1580647/json-why-are-forward-slashes-escaped
-    return json.dumps(value).replace("</", "<\\/")
-
-
-def json_decode(value):
-    """Returns Python objects for the given JSON string."""
-    return json.loads(to_basestring(value))
-
-
-def squeeze(value):
-    """Replace all sequences of whitespace chars with a single space."""
-    return re.sub(r"[\x00-\x20]+", " ", value).strip()
-
-
-def url_escape(value, plus=True):
-    """Returns a URL-encoded version of the given value.
-
-    If ``plus`` is true (the default), spaces will be represented
-    as "+" instead of "%20".  This is appropriate for query strings
-    but not for the path component of a URL.  Note that this default
-    is the reverse of Python's urllib module.
-
-    .. versionadded:: 3.1
-        The ``plus`` argument
-    """
-    quote = urllib_parse.quote_plus if plus else urllib_parse.quote
-    return quote(utf8(value))
-
-
-# python 3 changed things around enough that we need two separate
-# implementations of url_unescape.  We also need our own implementation
-# of parse_qs since python 3's version insists on decoding everything.
-if not PY3:
-    def url_unescape(value, encoding='utf-8', plus=True):
-        """Decodes the given value from a URL.
-
-        The argument may be either a byte or unicode string.
-
-        If encoding is None, the result will be a byte string.  Otherwise,
-        the result is a unicode string in the specified encoding.
-
-        If ``plus`` is true (the default), plus signs will be interpreted
-        as spaces (literal plus signs must be represented as "%2B").  This
-        is appropriate for query strings and form-encoded values but not
-        for the path component of a URL.  Note that this default is the
-        reverse of Python's urllib module.
-
-        .. versionadded:: 3.1
-           The ``plus`` argument
-        """
-        unquote = (urllib_parse.unquote_plus if plus else urllib_parse.unquote)
-        if encoding is None:
-            return unquote(utf8(value))
-        else:
-            return unicode_type(unquote(utf8(value)), encoding)
-
-    parse_qs_bytes = _parse_qs
-else:
-    def url_unescape(value, encoding='utf-8', plus=True):
-        """Decodes the given value from a URL.
-
-        The argument may be either a byte or unicode string.
-
-        If encoding is None, the result will be a byte string.  Otherwise,
-        the result is a unicode string in the specified encoding.
-
-        If ``plus`` is true (the default), plus signs will be interpreted
-        as spaces (literal plus signs must be represented as "%2B").  This
-        is appropriate for query strings and form-encoded values but not
-        for the path component of a URL.  Note that this default is the
-        reverse of Python's urllib module.
-
-        .. versionadded:: 3.1
-           The ``plus`` argument
-        """
-        if encoding is None:
-            if plus:
-                # unquote_to_bytes doesn't have a _plus variant
-                value = to_basestring(value).replace('+', ' ')
-            return urllib_parse.unquote_to_bytes(value)
-        else:
-            unquote = (urllib_parse.unquote_plus if plus
-                       else urllib_parse.unquote)
-            return unquote(to_basestring(value), encoding=encoding)
-
-    def parse_qs_bytes(qs, keep_blank_values=False, strict_parsing=False):
-        """Parses a query string like urlparse.parse_qs, but returns the
-        values as byte strings.
-
-        Keys still become type str (interpreted as latin1 in python3!)
-        because it's too painful to keep them as byte strings in
-        python3 and in practice they're nearly always ascii anyway.
-        """
-        # This is gross, but python3 doesn't give us another way.
-        # Latin1 is the universal donor of character encodings.
-        result = _parse_qs(qs, keep_blank_values, strict_parsing,
-                           encoding='latin1', errors='strict')
-        encoded = {}
-        for k, v in result.items():
-            encoded[k] = [i.encode('latin1') for i in v]
-        return encoded
-
-
-_UTF8_TYPES = (bytes, type(None))
-
-
-def utf8(value):
-    # type: (typing.Union[bytes,unicode_type,None])->typing.Union[bytes,None]
-    """Converts a string argument to a byte string.
-
-    If the argument is already a byte string or None, it is returned unchanged.
-    Otherwise it must be a unicode string and is encoded as utf8.
-    """
-    if isinstance(value, _UTF8_TYPES):
-        return value
-    if not isinstance(value, unicode_type):
-        raise TypeError(
-            "Expected bytes, unicode, or None; got %r" % type(value)
-        )
-    return value.encode("utf-8")
-
-
-_TO_UNICODE_TYPES = (unicode_type, type(None))
-
-
-def to_unicode(value):
-    """Converts a string argument to a unicode string.
-
-    If the argument is already a unicode string or None, it is returned
-    unchanged.  Otherwise it must be a byte string and is decoded as utf8.
-    """
-    if isinstance(value, _TO_UNICODE_TYPES):
-        return value
-    if not isinstance(value, bytes):
-        raise TypeError(
-            "Expected bytes, unicode, or None; got %r" % type(value)
-        )
-    return value.decode("utf-8")
-
-
-# to_unicode was previously named _unicode not because it was private,
-# but to avoid conflicts with the built-in unicode() function/type
-_unicode = to_unicode
-
-# When dealing with the standard library across python 2 and 3 it is
-# sometimes useful to have a direct conversion to the native string type
-if str is unicode_type:
-    native_str = to_unicode
-else:
-    native_str = utf8
-
-_BASESTRING_TYPES = (basestring_type, type(None))
-
-
-def to_basestring(value):
-    """Converts a string argument to a subclass of basestring.
-
-    In python2, byte and unicode strings are mostly interchangeable,
-    so functions that deal with a user-supplied argument in combination
-    with ascii string constants can use either and should return the type
-    the user supplied.  In python3, the two types are not interchangeable,
-    so this method is needed to convert byte strings to unicode.
-    """
-    if isinstance(value, _BASESTRING_TYPES):
-        return value
-    if not isinstance(value, bytes):
-        raise TypeError(
-            "Expected bytes, unicode, or None; got %r" % type(value)
-        )
-    return value.decode("utf-8")
-
-
-def recursive_unicode(obj):
-    """Walks a simple data structure, converting byte strings to unicode.
-
-    Supports lists, tuples, and dictionaries.
-    """
-    if isinstance(obj, dict):
-        return dict((recursive_unicode(k), recursive_unicode(v)) for (k, v) in obj.items())
-    elif isinstance(obj, list):
-        return list(recursive_unicode(i) for i in obj)
-    elif isinstance(obj, tuple):
-        return tuple(recursive_unicode(i) for i in obj)
-    elif isinstance(obj, bytes):
-        return to_unicode(obj)
-    else:
-        return obj
-
-
-# I originally used the regex from
-# http://daringfireball.net/2010/07/improved_regex_for_matching_urls
-# but it gets all exponential on certain patterns (such as too many trailing
-# dots), causing the regex matcher to never return.
-# This regex should avoid those problems.
-# Use to_unicode instead of tornado.util.u - we don't want backslashes getting
-# processed as escapes.
-_URL_RE = re.compile(to_unicode(r"""\b((?:([\w-]+):(/{1,3})|www[.])(?:(?:(?:[^\s&()]|&amp;|&quot;)*(?:[^!"#$%&'()*+,.:;<=>?@\[\]^`{|}~\s]))|(?:\((?:[^\s&()]|&amp;|&quot;)*\)))+)"""))
-
-
-def linkify(text, shorten=False, extra_params="",
-            require_protocol=False, permitted_protocols=["http", "https"]):
-    """Converts plain text into HTML with links.
-
-    For example: ``linkify("Hello http://tornadoweb.org!")`` would return
-    ``Hello <a href="http://tornadoweb.org">http://tornadoweb.org</a>!``
-
-    Parameters:
-
-    * ``shorten``: Long urls will be shortened for display.
-
-    * ``extra_params``: Extra text to include in the link tag, or a callable
-        taking the link as an argument and returning the extra text
-        e.g. ``linkify(text, extra_params='rel="nofollow" class="external"')``,
-        or::
-
-            def extra_params_cb(url):
-                if url.startswith("http://example.com"):
-                    return 'class="internal"'
-                else:
-                    return 'class="external" rel="nofollow"'
-            linkify(text, extra_params=extra_params_cb)
-
-    * ``require_protocol``: Only linkify urls which include a protocol. If
-        this is False, urls such as www.facebook.com will also be linkified.
-
-    * ``permitted_protocols``: List (or set) of protocols which should be
-        linkified, e.g. ``linkify(text, permitted_protocols=["http", "ftp",
-        "mailto"])``. It is very unsafe to include protocols such as
-        ``javascript``.
-    """
-    if extra_params and not callable(extra_params):
-        extra_params = " " + extra_params.strip()
-
-    def make_link(m):
-        url = m.group(1)
-        proto = m.group(2)
-        if require_protocol and not proto:
-            return url  # not protocol, no linkify
-
-        if proto and proto not in permitted_protocols:
-            return url  # bad protocol, no linkify
-
-        href = m.group(1)
-        if not proto:
-            href = "http://" + href   # no proto specified, use http
-
-        if callable(extra_params):
-            params = " " + extra_params(href).strip()
-        else:
-            params = extra_params
-
-        # clip long urls. max_len is just an approximation
-        max_len = 30
-        if shorten and len(url) > max_len:
-            before_clip = url
-            if proto:
-                proto_len = len(proto) + 1 + len(m.group(3) or "")  # +1 for :
-            else:
-                proto_len = 0
-
-            parts = url[proto_len:].split("/")
-            if len(parts) > 1:
-                # Grab the whole host part plus the first bit of the path
-                # The path is usually not that interesting once shortened
-                # (no more slug, etc), so it really just provides a little
-                # extra indication of shortening.
-                url = url[:proto_len] + parts[0] + "/" + \
-                    parts[1][:8].split('?')[0].split('.')[0]
-
-            if len(url) > max_len * 1.5:  # still too long
-                url = url[:max_len]
-
-            if url != before_clip:
-                amp = url.rfind('&')
-                # avoid splitting html char entities
-                if amp > max_len - 5:
-                    url = url[:amp]
-                url += "..."
-
-                if len(url) >= len(before_clip):
-                    url = before_clip
-                else:
-                    # full url is visible on mouse-over (for those who don't
-                    # have a status bar, such as Safari by default)
-                    params += ' title="%s"' % href
-
-        return u'<a href="%s"%s>%s</a>' % (href, params, url)
-
-    # First HTML-escape so that our strings are all safe.
-    # The regex is modified to avoid character entites other than &amp; so
-    # that we won't pick up &quot;, etc.
-    text = _unicode(xhtml_escape(text))
-    return _URL_RE.sub(make_link, text)
-
-
-def _convert_entity(m):
-    if m.group(1) == "#":
-        try:
-            if m.group(2)[:1].lower() == 'x':
-                return unichr(int(m.group(2)[1:], 16))
-            else:
-                return unichr(int(m.group(2)))
-        except ValueError:
-            return "&#%s;" % m.group(2)
-    try:
-        return _HTML_UNICODE_MAP[m.group(2)]
-    except KeyError:
-        return "&%s;" % m.group(2)
-
-
-def _build_unicode_map():
-    unicode_map = {}
-    for name, value in htmlentitydefs.name2codepoint.items():
-        unicode_map[name] = unichr(value)
-    return unicode_map
-
-
-_HTML_UNICODE_MAP = _build_unicode_map()
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Escaping/unescaping methods for HTML, JSON, URLs, and others. 
+ 
+Also includes a few other miscellaneous string manipulation functions that 
+have crept in over time. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import json 
+import re 
+ 
+from tornado.util import PY3, unicode_type, basestring_type 
+ 
+if PY3: 
+    from urllib.parse import parse_qs as _parse_qs 
+    import html.entities as htmlentitydefs 
+    import urllib.parse as urllib_parse 
+    unichr = chr 
+else: 
+    from urlparse import parse_qs as _parse_qs 
+    import htmlentitydefs 
+    import urllib as urllib_parse 
+ 
+try: 
+    import typing  # noqa 
+except ImportError: 
+    pass 
+ 
+ 
+_XHTML_ESCAPE_RE = re.compile('[&<>"\']') 
+_XHTML_ESCAPE_DICT = {'&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', 
+                      '\'': '&#39;'} 
+ 
+ 
+def xhtml_escape(value): 
+    """Escapes a string so it is valid within HTML or XML. 
+ 
+    Escapes the characters ``<``, ``>``, ``"``, ``'``, and ``&``. 
+    When used in attribute values the escaped strings must be enclosed 
+    in quotes. 
+ 
+    .. versionchanged:: 3.2 
+ 
+       Added the single quote to the list of escaped characters. 
+    """ 
+    return _XHTML_ESCAPE_RE.sub(lambda match: _XHTML_ESCAPE_DICT[match.group(0)], 
+                                to_basestring(value)) 
+ 
+ 
+def xhtml_unescape(value): 
+    """Un-escapes an XML-escaped string.""" 
+    return re.sub(r"&(#?)(\w+?);", _convert_entity, _unicode(value)) 
+ 
+ 
+# The fact that json_encode wraps json.dumps is an implementation detail. 
+# Please see https://github.com/tornadoweb/tornado/pull/706 
+# before sending a pull request that adds **kwargs to this function. 
+def json_encode(value): 
+    """JSON-encodes the given Python object.""" 
+    # JSON permits but does not require forward slashes to be escaped. 
+    # This is useful when json data is emitted in a <script> tag 
+    # in HTML, as it prevents </script> tags from prematurely terminating 
+    # the javascript.  Some json libraries do this escaping by default, 
+    # although python's standard library does not, so we do it here. 
+    # http://stackoverflow.com/questions/1580647/json-why-are-forward-slashes-escaped 
+    return json.dumps(value).replace("</", "<\\/") 
+ 
+ 
+def json_decode(value): 
+    """Returns Python objects for the given JSON string.""" 
+    return json.loads(to_basestring(value)) 
+ 
+ 
+def squeeze(value): 
+    """Replace all sequences of whitespace chars with a single space.""" 
+    return re.sub(r"[\x00-\x20]+", " ", value).strip() 
+ 
+ 
+def url_escape(value, plus=True): 
+    """Returns a URL-encoded version of the given value. 
+ 
+    If ``plus`` is true (the default), spaces will be represented 
+    as "+" instead of "%20".  This is appropriate for query strings 
+    but not for the path component of a URL.  Note that this default 
+    is the reverse of Python's urllib module. 
+ 
+    .. versionadded:: 3.1 
+        The ``plus`` argument 
+    """ 
+    quote = urllib_parse.quote_plus if plus else urllib_parse.quote 
+    return quote(utf8(value)) 
+ 
+ 
+# python 3 changed things around enough that we need two separate 
+# implementations of url_unescape.  We also need our own implementation 
+# of parse_qs since python 3's version insists on decoding everything. 
+if not PY3: 
+    def url_unescape(value, encoding='utf-8', plus=True): 
+        """Decodes the given value from a URL. 
+ 
+        The argument may be either a byte or unicode string. 
+ 
+        If encoding is None, the result will be a byte string.  Otherwise, 
+        the result is a unicode string in the specified encoding. 
+ 
+        If ``plus`` is true (the default), plus signs will be interpreted 
+        as spaces (literal plus signs must be represented as "%2B").  This 
+        is appropriate for query strings and form-encoded values but not 
+        for the path component of a URL.  Note that this default is the 
+        reverse of Python's urllib module. 
+ 
+        .. versionadded:: 3.1 
+           The ``plus`` argument 
+        """ 
+        unquote = (urllib_parse.unquote_plus if plus else urllib_parse.unquote) 
+        if encoding is None: 
+            return unquote(utf8(value)) 
+        else: 
+            return unicode_type(unquote(utf8(value)), encoding) 
+ 
+    parse_qs_bytes = _parse_qs 
+else: 
+    def url_unescape(value, encoding='utf-8', plus=True): 
+        """Decodes the given value from a URL. 
+ 
+        The argument may be either a byte or unicode string. 
+ 
+        If encoding is None, the result will be a byte string.  Otherwise, 
+        the result is a unicode string in the specified encoding. 
+ 
+        If ``plus`` is true (the default), plus signs will be interpreted 
+        as spaces (literal plus signs must be represented as "%2B").  This 
+        is appropriate for query strings and form-encoded values but not 
+        for the path component of a URL.  Note that this default is the 
+        reverse of Python's urllib module. 
+ 
+        .. versionadded:: 3.1 
+           The ``plus`` argument 
+        """ 
+        if encoding is None: 
+            if plus: 
+                # unquote_to_bytes doesn't have a _plus variant 
+                value = to_basestring(value).replace('+', ' ') 
+            return urllib_parse.unquote_to_bytes(value) 
+        else: 
+            unquote = (urllib_parse.unquote_plus if plus 
+                       else urllib_parse.unquote) 
+            return unquote(to_basestring(value), encoding=encoding) 
+ 
+    def parse_qs_bytes(qs, keep_blank_values=False, strict_parsing=False): 
+        """Parses a query string like urlparse.parse_qs, but returns the 
+        values as byte strings. 
+ 
+        Keys still become type str (interpreted as latin1 in python3!) 
+        because it's too painful to keep them as byte strings in 
+        python3 and in practice they're nearly always ascii anyway. 
+        """ 
+        # This is gross, but python3 doesn't give us another way. 
+        # Latin1 is the universal donor of character encodings. 
+        result = _parse_qs(qs, keep_blank_values, strict_parsing, 
+                           encoding='latin1', errors='strict') 
+        encoded = {} 
+        for k, v in result.items(): 
+            encoded[k] = [i.encode('latin1') for i in v] 
+        return encoded 
+ 
+ 
+_UTF8_TYPES = (bytes, type(None)) 
+ 
+ 
+def utf8(value): 
+    # type: (typing.Union[bytes,unicode_type,None])->typing.Union[bytes,None] 
+    """Converts a string argument to a byte string. 
+ 
+    If the argument is already a byte string or None, it is returned unchanged. 
+    Otherwise it must be a unicode string and is encoded as utf8. 
+    """ 
+    if isinstance(value, _UTF8_TYPES): 
+        return value 
+    if not isinstance(value, unicode_type): 
+        raise TypeError( 
+            "Expected bytes, unicode, or None; got %r" % type(value) 
+        ) 
+    return value.encode("utf-8") 
+ 
+ 
+_TO_UNICODE_TYPES = (unicode_type, type(None)) 
+ 
+ 
+def to_unicode(value): 
+    """Converts a string argument to a unicode string. 
+ 
+    If the argument is already a unicode string or None, it is returned 
+    unchanged.  Otherwise it must be a byte string and is decoded as utf8. 
+    """ 
+    if isinstance(value, _TO_UNICODE_TYPES): 
+        return value 
+    if not isinstance(value, bytes): 
+        raise TypeError( 
+            "Expected bytes, unicode, or None; got %r" % type(value) 
+        ) 
+    return value.decode("utf-8") 
+ 
+ 
+# to_unicode was previously named _unicode not because it was private, 
+# but to avoid conflicts with the built-in unicode() function/type 
+_unicode = to_unicode 
+ 
+# When dealing with the standard library across python 2 and 3 it is 
+# sometimes useful to have a direct conversion to the native string type 
+if str is unicode_type: 
+    native_str = to_unicode 
+else: 
+    native_str = utf8 
+ 
+_BASESTRING_TYPES = (basestring_type, type(None)) 
+ 
+ 
+def to_basestring(value): 
+    """Converts a string argument to a subclass of basestring. 
+ 
+    In python2, byte and unicode strings are mostly interchangeable, 
+    so functions that deal with a user-supplied argument in combination 
+    with ascii string constants can use either and should return the type 
+    the user supplied.  In python3, the two types are not interchangeable, 
+    so this method is needed to convert byte strings to unicode. 
+    """ 
+    if isinstance(value, _BASESTRING_TYPES): 
+        return value 
+    if not isinstance(value, bytes): 
+        raise TypeError( 
+            "Expected bytes, unicode, or None; got %r" % type(value) 
+        ) 
+    return value.decode("utf-8") 
+ 
+ 
+def recursive_unicode(obj): 
+    """Walks a simple data structure, converting byte strings to unicode. 
+ 
+    Supports lists, tuples, and dictionaries. 
+    """ 
+    if isinstance(obj, dict): 
+        return dict((recursive_unicode(k), recursive_unicode(v)) for (k, v) in obj.items()) 
+    elif isinstance(obj, list): 
+        return list(recursive_unicode(i) for i in obj) 
+    elif isinstance(obj, tuple): 
+        return tuple(recursive_unicode(i) for i in obj) 
+    elif isinstance(obj, bytes): 
+        return to_unicode(obj) 
+    else: 
+        return obj 
+ 
+ 
+# I originally used the regex from 
+# http://daringfireball.net/2010/07/improved_regex_for_matching_urls 
+# but it gets all exponential on certain patterns (such as too many trailing 
+# dots), causing the regex matcher to never return. 
+# This regex should avoid those problems. 
+# Use to_unicode instead of tornado.util.u - we don't want backslashes getting 
+# processed as escapes. 
+_URL_RE = re.compile(to_unicode(r"""\b((?:([\w-]+):(/{1,3})|www[.])(?:(?:(?:[^\s&()]|&amp;|&quot;)*(?:[^!"#$%&'()*+,.:;<=>?@\[\]^`{|}~\s]))|(?:\((?:[^\s&()]|&amp;|&quot;)*\)))+)""")) 
+ 
+ 
+def linkify(text, shorten=False, extra_params="", 
+            require_protocol=False, permitted_protocols=["http", "https"]): 
+    """Converts plain text into HTML with links. 
+ 
+    For example: ``linkify("Hello http://tornadoweb.org!")`` would return 
+    ``Hello <a href="http://tornadoweb.org">http://tornadoweb.org</a>!`` 
+ 
+    Parameters: 
+ 
+    * ``shorten``: Long urls will be shortened for display. 
+ 
+    * ``extra_params``: Extra text to include in the link tag, or a callable 
+        taking the link as an argument and returning the extra text 
+        e.g. ``linkify(text, extra_params='rel="nofollow" class="external"')``, 
+        or:: 
+ 
+            def extra_params_cb(url): 
+                if url.startswith("http://example.com"): 
+                    return 'class="internal"' 
+                else: 
+                    return 'class="external" rel="nofollow"' 
+            linkify(text, extra_params=extra_params_cb) 
+ 
+    * ``require_protocol``: Only linkify urls which include a protocol. If 
+        this is False, urls such as www.facebook.com will also be linkified. 
+ 
+    * ``permitted_protocols``: List (or set) of protocols which should be 
+        linkified, e.g. ``linkify(text, permitted_protocols=["http", "ftp", 
+        "mailto"])``. It is very unsafe to include protocols such as 
+        ``javascript``. 
+    """ 
+    if extra_params and not callable(extra_params): 
+        extra_params = " " + extra_params.strip() 
+ 
+    def make_link(m): 
+        url = m.group(1) 
+        proto = m.group(2) 
+        if require_protocol and not proto: 
+            return url  # not protocol, no linkify 
+ 
+        if proto and proto not in permitted_protocols: 
+            return url  # bad protocol, no linkify 
+ 
+        href = m.group(1) 
+        if not proto: 
+            href = "http://" + href   # no proto specified, use http 
+ 
+        if callable(extra_params): 
+            params = " " + extra_params(href).strip() 
+        else: 
+            params = extra_params 
+ 
+        # clip long urls. max_len is just an approximation 
+        max_len = 30 
+        if shorten and len(url) > max_len: 
+            before_clip = url 
+            if proto: 
+                proto_len = len(proto) + 1 + len(m.group(3) or "")  # +1 for : 
+            else: 
+                proto_len = 0 
+ 
+            parts = url[proto_len:].split("/") 
+            if len(parts) > 1: 
+                # Grab the whole host part plus the first bit of the path 
+                # The path is usually not that interesting once shortened 
+                # (no more slug, etc), so it really just provides a little 
+                # extra indication of shortening. 
+                url = url[:proto_len] + parts[0] + "/" + \ 
+                    parts[1][:8].split('?')[0].split('.')[0] 
+ 
+            if len(url) > max_len * 1.5:  # still too long 
+                url = url[:max_len] 
+ 
+            if url != before_clip: 
+                amp = url.rfind('&') 
+                # avoid splitting html char entities 
+                if amp > max_len - 5: 
+                    url = url[:amp] 
+                url += "..." 
+ 
+                if len(url) >= len(before_clip): 
+                    url = before_clip 
+                else: 
+                    # full url is visible on mouse-over (for those who don't 
+                    # have a status bar, such as Safari by default) 
+                    params += ' title="%s"' % href 
+ 
+        return u'<a href="%s"%s>%s</a>' % (href, params, url) 
+ 
+    # First HTML-escape so that our strings are all safe. 
+    # The regex is modified to avoid character entites other than &amp; so 
+    # that we won't pick up &quot;, etc. 
+    text = _unicode(xhtml_escape(text)) 
+    return _URL_RE.sub(make_link, text) 
+ 
+ 
+def _convert_entity(m): 
+    if m.group(1) == "#": 
+        try: 
+            if m.group(2)[:1].lower() == 'x': 
+                return unichr(int(m.group(2)[1:], 16)) 
+            else: 
+                return unichr(int(m.group(2))) 
+        except ValueError: 
+            return "&#%s;" % m.group(2) 
+    try: 
+        return _HTML_UNICODE_MAP[m.group(2)] 
+    except KeyError: 
+        return "&%s;" % m.group(2) 
+ 
+ 
+def _build_unicode_map(): 
+    unicode_map = {} 
+    for name, value in htmlentitydefs.name2codepoint.items(): 
+        unicode_map[name] = unichr(value) 
+    return unicode_map 
+ 
+ 
+_HTML_UNICODE_MAP = _build_unicode_map() 
diff --git a/contrib/python/tornado/tornado-4/tornado/gen.py b/contrib/python/tornado/tornado-4/tornado/gen.py
index 89a4dd7c7a..cef0935a92 100644
--- a/contrib/python/tornado/tornado-4/tornado/gen.py
+++ b/contrib/python/tornado/tornado-4/tornado/gen.py
@@ -1,1304 +1,1304 @@
-"""``tornado.gen`` is a generator-based interface to make it easier to
-work in an asynchronous environment.  Code using the ``gen`` module
-is technically asynchronous, but it is written as a single generator
-instead of a collection of separate functions.
-
-For example, the following asynchronous handler:
-
-.. testcode::
-
-    class AsyncHandler(RequestHandler):
-        @asynchronous
-        def get(self):
-            http_client = AsyncHTTPClient()
-            http_client.fetch("http://example.com",
-                              callback=self.on_fetch)
-
-        def on_fetch(self, response):
-            do_something_with_response(response)
-            self.render("template.html")
-
-.. testoutput::
-   :hide:
-
-could be written with ``gen`` as:
-
-.. testcode::
-
-    class GenAsyncHandler(RequestHandler):
-        @gen.coroutine
-        def get(self):
-            http_client = AsyncHTTPClient()
-            response = yield http_client.fetch("http://example.com")
-            do_something_with_response(response)
-            self.render("template.html")
-
-.. testoutput::
-   :hide:
-
-Most asynchronous functions in Tornado return a `.Future`;
-yielding this object returns its `~.Future.result`.
-
-You can also yield a list or dict of ``Futures``, which will be
-started at the same time and run in parallel; a list or dict of results will
-be returned when they are all finished:
-
-.. testcode::
-
-    @gen.coroutine
-    def get(self):
-        http_client = AsyncHTTPClient()
-        response1, response2 = yield [http_client.fetch(url1),
-                                      http_client.fetch(url2)]
-        response_dict = yield dict(response3=http_client.fetch(url3),
-                                   response4=http_client.fetch(url4))
-        response3 = response_dict['response3']
-        response4 = response_dict['response4']
-
-.. testoutput::
-   :hide:
-
-If the `~functools.singledispatch` library is available (standard in
-Python 3.4, available via the `singledispatch
-<https://pypi.python.org/pypi/singledispatch>`_ package on older
-versions), additional types of objects may be yielded. Tornado includes
-support for ``asyncio.Future`` and Twisted's ``Deferred`` class when
-``tornado.platform.asyncio`` and ``tornado.platform.twisted`` are imported.
-See the `convert_yielded` function to extend this mechanism.
-
-.. versionchanged:: 3.2
-   Dict support added.
-
-.. versionchanged:: 4.1
-   Support added for yielding ``asyncio`` Futures and Twisted Deferreds
-   via ``singledispatch``.
-
-"""
-from __future__ import absolute_import, division, print_function
-
-import collections
-import functools
-import itertools
-import os
-import sys
-import textwrap
-import types
-import weakref
-
-from tornado.concurrent import Future, TracebackFuture, is_future, chain_future
-from tornado.ioloop import IOLoop
-from tornado.log import app_log
-from tornado import stack_context
-from tornado.util import PY3, raise_exc_info
-
-try:
-    try:
-        # py34+
-        from functools import singledispatch  # type: ignore
-    except ImportError:
-        from singledispatch import singledispatch  # backport
-except ImportError:
-    # In most cases, singledispatch is required (to avoid
-    # difficult-to-diagnose problems in which the functionality
-    # available differs depending on which invisble packages are
-    # installed). However, in Google App Engine third-party
-    # dependencies are more trouble so we allow this module to be
-    # imported without it.
-    if 'APPENGINE_RUNTIME' not in os.environ:
-        raise
-    singledispatch = None
-
-try:
-    try:
-        # py35+
-        from collections.abc import Generator as GeneratorType  # type: ignore
-    except ImportError:
-        from backports_abc import Generator as GeneratorType  # type: ignore
-
-    try:
-        # py35+
-        from inspect import isawaitable  # type: ignore
-    except ImportError:
-        from backports_abc import isawaitable
-except ImportError:
-    if 'APPENGINE_RUNTIME' not in os.environ:
-        raise
-    from types import GeneratorType
-
-    def isawaitable(x):  # type: ignore
-        return False
-
-if PY3:
-    import builtins
-else:
-    import __builtin__ as builtins
-
-
-class KeyReuseError(Exception):
-    pass
-
-
-class UnknownKeyError(Exception):
-    pass
-
-
-class LeakedCallbackError(Exception):
-    pass
-
-
-class BadYieldError(Exception):
-    pass
-
-
-class ReturnValueIgnoredError(Exception):
-    pass
-
-
-class TimeoutError(Exception):
-    """Exception raised by ``with_timeout``."""
-
-
-def _value_from_stopiteration(e):
-    try:
-        # StopIteration has a value attribute beginning in py33.
-        # So does our Return class.
-        return e.value
-    except AttributeError:
-        pass
-    try:
-        # Cython backports coroutine functionality by putting the value in
-        # e.args[0].
-        return e.args[0]
-    except (AttributeError, IndexError):
-        return None
-
-
-def engine(func):
-    """Callback-oriented decorator for asynchronous generators.
-
-    This is an older interface; for new code that does not need to be
-    compatible with versions of Tornado older than 3.0 the
-    `coroutine` decorator is recommended instead.
-
-    This decorator is similar to `coroutine`, except it does not
-    return a `.Future` and the ``callback`` argument is not treated
-    specially.
-
-    In most cases, functions decorated with `engine` should take
-    a ``callback`` argument and invoke it with their result when
-    they are finished.  One notable exception is the
-    `~tornado.web.RequestHandler` :ref:`HTTP verb methods <verbs>`,
-    which use ``self.finish()`` in place of a callback argument.
-    """
-    func = _make_coroutine_wrapper(func, replace_callback=False)
-
-    @functools.wraps(func)
-    def wrapper(*args, **kwargs):
-        future = func(*args, **kwargs)
-
-        def final_callback(future):
-            if future.result() is not None:
-                raise ReturnValueIgnoredError(
-                    "@gen.engine functions cannot return values: %r" %
-                    (future.result(),))
-        # The engine interface doesn't give us any way to return
-        # errors but to raise them into the stack context.
-        # Save the stack context here to use when the Future has resolved.
-        future.add_done_callback(stack_context.wrap(final_callback))
-    return wrapper
-
-
-def coroutine(func, replace_callback=True):
-    """Decorator for asynchronous generators.
-
-    Any generator that yields objects from this module must be wrapped
-    in either this decorator or `engine`.
-
-    Coroutines may "return" by raising the special exception
-    `Return(value) <Return>`.  In Python 3.3+, it is also possible for
-    the function to simply use the ``return value`` statement (prior to
-    Python 3.3 generators were not allowed to also return values).
-    In all versions of Python a coroutine that simply wishes to exit
-    early may use the ``return`` statement without a value.
-
-    Functions with this decorator return a `.Future`.  Additionally,
-    they may be called with a ``callback`` keyword argument, which
-    will be invoked with the future's result when it resolves.  If the
-    coroutine fails, the callback will not be run and an exception
-    will be raised into the surrounding `.StackContext`.  The
-    ``callback`` argument is not visible inside the decorated
-    function; it is handled by the decorator itself.
-
-    From the caller's perspective, ``@gen.coroutine`` is similar to
-    the combination of ``@return_future`` and ``@gen.engine``.
-
-    .. warning::
-
-       When exceptions occur inside a coroutine, the exception
-       information will be stored in the `.Future` object. You must
-       examine the result of the `.Future` object, or the exception
-       may go unnoticed by your code. This means yielding the function
-       if called from another coroutine, using something like
-       `.IOLoop.run_sync` for top-level calls, or passing the `.Future`
-       to `.IOLoop.add_future`.
-
-    """
-    return _make_coroutine_wrapper(func, replace_callback=True)
-
-
-# Ties lifetime of runners to their result futures. Github Issue #1769
-# Generators, like any object in Python, must be strong referenced
-# in order to not be cleaned up by the garbage collector. When using
-# coroutines, the Runner object is what strong-refs the inner
-# generator. However, the only item that strong-reffed the Runner
-# was the last Future that the inner generator yielded (via the
-# Future's internal done_callback list). Usually this is enough, but
-# it is also possible for this Future to not have any strong references
-# other than other objects referenced by the Runner object (usually
-# when using other callback patterns and/or weakrefs). In this
-# situation, if a garbage collection ran, a cycle would be detected and
-# Runner objects could be destroyed along with their inner generators
-# and everything in their local scope.
-# This map provides strong references to Runner objects as long as
-# their result future objects also have strong references (typically
-# from the parent coroutine's Runner). This keeps the coroutine's
-# Runner alive.
-_futures_to_runners = weakref.WeakKeyDictionary()
-
-
-def _make_coroutine_wrapper(func, replace_callback):
-    """The inner workings of ``@gen.coroutine`` and ``@gen.engine``.
-
-    The two decorators differ in their treatment of the ``callback``
-    argument, so we cannot simply implement ``@engine`` in terms of
-    ``@coroutine``.
-    """
-    # On Python 3.5, set the coroutine flag on our generator, to allow it
-    # to be used with 'await'.
-    wrapped = func
-    if hasattr(types, 'coroutine'):
-        func = types.coroutine(func)
-
-    @functools.wraps(wrapped)
-    def wrapper(*args, **kwargs):
-        future = TracebackFuture()
-
-        if replace_callback and 'callback' in kwargs:
-            callback = kwargs.pop('callback')
-            IOLoop.current().add_future(
-                future, lambda future: callback(future.result()))
-
-        try:
-            result = func(*args, **kwargs)
-        except (Return, StopIteration) as e:
-            result = _value_from_stopiteration(e)
-        except Exception:
-            future.set_exc_info(sys.exc_info())
-            return future
-        else:
-            if isinstance(result, GeneratorType):
-                # Inline the first iteration of Runner.run.  This lets us
-                # avoid the cost of creating a Runner when the coroutine
-                # never actually yields, which in turn allows us to
-                # use "optional" coroutines in critical path code without
-                # performance penalty for the synchronous case.
-                try:
-                    orig_stack_contexts = stack_context._state.contexts
-                    yielded = next(result)
-                    if stack_context._state.contexts is not orig_stack_contexts:
-                        yielded = TracebackFuture()
-                        yielded.set_exception(
-                            stack_context.StackContextInconsistentError(
-                                'stack_context inconsistency (probably caused '
-                                'by yield within a "with StackContext" block)'))
-                except (StopIteration, Return) as e:
-                    future.set_result(_value_from_stopiteration(e))
-                except Exception:
-                    future.set_exc_info(sys.exc_info())
-                else:
-                    _futures_to_runners[future] = Runner(result, future, yielded)
-                yielded = None
-                try:
-                    return future
-                finally:
-                    # Subtle memory optimization: if next() raised an exception,
-                    # the future's exc_info contains a traceback which
-                    # includes this stack frame.  This creates a cycle,
-                    # which will be collected at the next full GC but has
-                    # been shown to greatly increase memory usage of
-                    # benchmarks (relative to the refcount-based scheme
-                    # used in the absence of cycles).  We can avoid the
-                    # cycle by clearing the local variable after we return it.
-                    future = None
-        future.set_result(result)
-        return future
-
-    wrapper.__wrapped__ = wrapped
-    wrapper.__tornado_coroutine__ = True
-    return wrapper
-
-
-def is_coroutine_function(func):
-    """Return whether *func* is a coroutine function, i.e. a function
-    wrapped with `~.gen.coroutine`.
-
-    .. versionadded:: 4.5
-    """
-    return getattr(func, '__tornado_coroutine__', False)
-
-
-class Return(Exception):
-    """Special exception to return a value from a `coroutine`.
-
-    If this exception is raised, its value argument is used as the
-    result of the coroutine::
-
-        @gen.coroutine
-        def fetch_json(url):
-            response = yield AsyncHTTPClient().fetch(url)
-            raise gen.Return(json_decode(response.body))
-
-    In Python 3.3, this exception is no longer necessary: the ``return``
-    statement can be used directly to return a value (previously
-    ``yield`` and ``return`` with a value could not be combined in the
-    same function).
-
-    By analogy with the return statement, the value argument is optional,
-    but it is never necessary to ``raise gen.Return()``.  The ``return``
-    statement can be used with no arguments instead.
-    """
-    def __init__(self, value=None):
-        super(Return, self).__init__()
-        self.value = value
-        # Cython recognizes subclasses of StopIteration with a .args tuple.
-        self.args = (value,)
-
-
-class WaitIterator(object):
-    """Provides an iterator to yield the results of futures as they finish.
-
-    Yielding a set of futures like this:
-
-    ``results = yield [future1, future2]``
-
-    pauses the coroutine until both ``future1`` and ``future2``
-    return, and then restarts the coroutine with the results of both
-    futures. If either future is an exception, the expression will
-    raise that exception and all the results will be lost.
-
-    If you need to get the result of each future as soon as possible,
-    or if you need the result of some futures even if others produce
-    errors, you can use ``WaitIterator``::
-
-      wait_iterator = gen.WaitIterator(future1, future2)
-      while not wait_iterator.done():
-          try:
-              result = yield wait_iterator.next()
-          except Exception as e:
-              print("Error {} from {}".format(e, wait_iterator.current_future))
-          else:
-              print("Result {} received from {} at {}".format(
-                  result, wait_iterator.current_future,
-                  wait_iterator.current_index))
-
-    Because results are returned as soon as they are available the
-    output from the iterator *will not be in the same order as the
-    input arguments*. If you need to know which future produced the
-    current result, you can use the attributes
-    ``WaitIterator.current_future``, or ``WaitIterator.current_index``
-    to get the index of the future from the input list. (if keyword
-    arguments were used in the construction of the `WaitIterator`,
-    ``current_index`` will use the corresponding keyword).
-
-    On Python 3.5, `WaitIterator` implements the async iterator
-    protocol, so it can be used with the ``async for`` statement (note
-    that in this version the entire iteration is aborted if any value
-    raises an exception, while the previous example can continue past
-    individual errors)::
-
-      async for result in gen.WaitIterator(future1, future2):
-          print("Result {} received from {} at {}".format(
-              result, wait_iterator.current_future,
-              wait_iterator.current_index))
-
-    .. versionadded:: 4.1
-
-    .. versionchanged:: 4.3
-       Added ``async for`` support in Python 3.5.
-
-    """
-    def __init__(self, *args, **kwargs):
-        if args and kwargs:
-            raise ValueError(
-                "You must provide args or kwargs, not both")
-
-        if kwargs:
-            self._unfinished = dict((f, k) for (k, f) in kwargs.items())
-            futures = list(kwargs.values())
-        else:
-            self._unfinished = dict((f, i) for (i, f) in enumerate(args))
-            futures = args
-
-        self._finished = collections.deque()
-        self.current_index = self.current_future = None
-        self._running_future = None
-
-        for future in futures:
-            future.add_done_callback(self._done_callback)
-
-    def done(self):
-        """Returns True if this iterator has no more results."""
-        if self._finished or self._unfinished:
-            return False
-        # Clear the 'current' values when iteration is done.
-        self.current_index = self.current_future = None
-        return True
-
-    def next(self):
-        """Returns a `.Future` that will yield the next available result.
-
-        Note that this `.Future` will not be the same object as any of
-        the inputs.
-        """
-        self._running_future = TracebackFuture()
-
-        if self._finished:
-            self._return_result(self._finished.popleft())
-
-        return self._running_future
-
-    def _done_callback(self, done):
-        if self._running_future and not self._running_future.done():
-            self._return_result(done)
-        else:
-            self._finished.append(done)
-
-    def _return_result(self, done):
-        """Called set the returned future's state that of the future
-        we yielded, and set the current future for the iterator.
-        """
-        chain_future(done, self._running_future)
-
-        self.current_future = done
-        self.current_index = self._unfinished.pop(done)
-
-    @coroutine
-    def __aiter__(self):
-        raise Return(self)
-
-    def __anext__(self):
-        if self.done():
-            # Lookup by name to silence pyflakes on older versions.
-            raise getattr(builtins, 'StopAsyncIteration')()
-        return self.next()
-
-
-class YieldPoint(object):
-    """Base class for objects that may be yielded from the generator.
-
-    .. deprecated:: 4.0
-       Use `Futures <.Future>` instead.
-    """
-    def start(self, runner):
-        """Called by the runner after the generator has yielded.
-
-        No other methods will be called on this object before ``start``.
-        """
-        raise NotImplementedError()
-
-    def is_ready(self):
-        """Called by the runner to determine whether to resume the generator.
-
-        Returns a boolean; may be called more than once.
-        """
-        raise NotImplementedError()
-
-    def get_result(self):
-        """Returns the value to use as the result of the yield expression.
-
-        This method will only be called once, and only after `is_ready`
-        has returned true.
-        """
-        raise NotImplementedError()
-
-
-class Callback(YieldPoint):
-    """Returns a callable object that will allow a matching `Wait` to proceed.
-
-    The key may be any value suitable for use as a dictionary key, and is
-    used to match ``Callbacks`` to their corresponding ``Waits``.  The key
-    must be unique among outstanding callbacks within a single run of the
-    generator function, but may be reused across different runs of the same
-    function (so constants generally work fine).
-
-    The callback may be called with zero or one arguments; if an argument
-    is given it will be returned by `Wait`.
-
-    .. deprecated:: 4.0
-       Use `Futures <.Future>` instead.
-    """
-    def __init__(self, key):
-        self.key = key
-
-    def start(self, runner):
-        self.runner = runner
-        runner.register_callback(self.key)
-
-    def is_ready(self):
-        return True
-
-    def get_result(self):
-        return self.runner.result_callback(self.key)
-
-
-class Wait(YieldPoint):
-    """Returns the argument passed to the result of a previous `Callback`.
-
-    .. deprecated:: 4.0
-       Use `Futures <.Future>` instead.
-    """
-    def __init__(self, key):
-        self.key = key
-
-    def start(self, runner):
-        self.runner = runner
-
-    def is_ready(self):
-        return self.runner.is_ready(self.key)
-
-    def get_result(self):
-        return self.runner.pop_result(self.key)
-
-
-class WaitAll(YieldPoint):
-    """Returns the results of multiple previous `Callbacks <Callback>`.
-
-    The argument is a sequence of `Callback` keys, and the result is
-    a list of results in the same order.
-
-    `WaitAll` is equivalent to yielding a list of `Wait` objects.
-
-    .. deprecated:: 4.0
-       Use `Futures <.Future>` instead.
-    """
-    def __init__(self, keys):
-        self.keys = keys
-
-    def start(self, runner):
-        self.runner = runner
-
-    def is_ready(self):
-        return all(self.runner.is_ready(key) for key in self.keys)
-
-    def get_result(self):
-        return [self.runner.pop_result(key) for key in self.keys]
-
-
-def Task(func, *args, **kwargs):
-    """Adapts a callback-based asynchronous function for use in coroutines.
-
-    Takes a function (and optional additional arguments) and runs it with
-    those arguments plus a ``callback`` keyword argument.  The argument passed
-    to the callback is returned as the result of the yield expression.
-
-    .. versionchanged:: 4.0
-       ``gen.Task`` is now a function that returns a `.Future`, instead of
-       a subclass of `YieldPoint`.  It still behaves the same way when
-       yielded.
-    """
-    future = Future()
-
-    def handle_exception(typ, value, tb):
-        if future.done():
-            return False
-        future.set_exc_info((typ, value, tb))
-        return True
-
-    def set_result(result):
-        if future.done():
-            return
-        future.set_result(result)
-    with stack_context.ExceptionStackContext(handle_exception):
-        func(*args, callback=_argument_adapter(set_result), **kwargs)
-    return future
-
-
-class YieldFuture(YieldPoint):
-    def __init__(self, future, io_loop=None):
-        """Adapts a `.Future` to the `YieldPoint` interface.
-
-        .. versionchanged:: 4.1
-           The ``io_loop`` argument is deprecated.
-        """
-        self.future = future
-        self.io_loop = io_loop or IOLoop.current()
-
-    def start(self, runner):
-        if not self.future.done():
-            self.runner = runner
-            self.key = object()
-            runner.register_callback(self.key)
-            self.io_loop.add_future(self.future, runner.result_callback(self.key))
-        else:
-            self.runner = None
-            self.result_fn = self.future.result
-
-    def is_ready(self):
-        if self.runner is not None:
-            return self.runner.is_ready(self.key)
-        else:
-            return True
-
-    def get_result(self):
-        if self.runner is not None:
-            return self.runner.pop_result(self.key).result()
-        else:
-            return self.result_fn()
-
-
-def _contains_yieldpoint(children):
-    """Returns True if ``children`` contains any YieldPoints.
-
-    ``children`` may be a dict or a list, as used by `MultiYieldPoint`
-    and `multi_future`.
-    """
-    if isinstance(children, dict):
-        return any(isinstance(i, YieldPoint) for i in children.values())
-    if isinstance(children, list):
-        return any(isinstance(i, YieldPoint) for i in children)
-    return False
-
-
-def multi(children, quiet_exceptions=()):
-    """Runs multiple asynchronous operations in parallel.
-
-    ``children`` may either be a list or a dict whose values are
-    yieldable objects. ``multi()`` returns a new yieldable
-    object that resolves to a parallel structure containing their
-    results. If ``children`` is a list, the result is a list of
-    results in the same order; if it is a dict, the result is a dict
-    with the same keys.
-
-    That is, ``results = yield multi(list_of_futures)`` is equivalent
-    to::
-
-        results = []
-        for future in list_of_futures:
-            results.append(yield future)
-
-    If any children raise exceptions, ``multi()`` will raise the first
-    one. All others will be logged, unless they are of types
-    contained in the ``quiet_exceptions`` argument.
-
-    If any of the inputs are `YieldPoints <YieldPoint>`, the returned
-    yieldable object is a `YieldPoint`. Otherwise, returns a `.Future`.
-    This means that the result of `multi` can be used in a native
-    coroutine if and only if all of its children can be.
-
-    In a ``yield``-based coroutine, it is not normally necessary to
-    call this function directly, since the coroutine runner will
-    do it automatically when a list or dict is yielded. However,
-    it is necessary in ``await``-based coroutines, or to pass
-    the ``quiet_exceptions`` argument.
-
-    This function is available under the names ``multi()`` and ``Multi()``
-    for historical reasons.
-
-    .. versionchanged:: 4.2
-       If multiple yieldables fail, any exceptions after the first
-       (which is raised) will be logged. Added the ``quiet_exceptions``
-       argument to suppress this logging for selected exception types.
-
-    .. versionchanged:: 4.3
-       Replaced the class ``Multi`` and the function ``multi_future``
-       with a unified function ``multi``. Added support for yieldables
-       other than `YieldPoint` and `.Future`.
-
-    """
-    if _contains_yieldpoint(children):
-        return MultiYieldPoint(children, quiet_exceptions=quiet_exceptions)
-    else:
-        return multi_future(children, quiet_exceptions=quiet_exceptions)
-
-
-Multi = multi
-
-
-class MultiYieldPoint(YieldPoint):
-    """Runs multiple asynchronous operations in parallel.
-
-    This class is similar to `multi`, but it always creates a stack
-    context even when no children require it. It is not compatible with
-    native coroutines.
-
-    .. versionchanged:: 4.2
-       If multiple ``YieldPoints`` fail, any exceptions after the first
-       (which is raised) will be logged. Added the ``quiet_exceptions``
-       argument to suppress this logging for selected exception types.
-
-    .. versionchanged:: 4.3
-       Renamed from ``Multi`` to ``MultiYieldPoint``. The name ``Multi``
-       remains as an alias for the equivalent `multi` function.
-
-    .. deprecated:: 4.3
-       Use `multi` instead.
-    """
-    def __init__(self, children, quiet_exceptions=()):
-        self.keys = None
-        if isinstance(children, dict):
-            self.keys = list(children.keys())
-            children = children.values()
-        self.children = []
-        for i in children:
-            if not isinstance(i, YieldPoint):
-                i = convert_yielded(i)
-            if is_future(i):
-                i = YieldFuture(i)
-            self.children.append(i)
-        assert all(isinstance(i, YieldPoint) for i in self.children)
-        self.unfinished_children = set(self.children)
-        self.quiet_exceptions = quiet_exceptions
-
-    def start(self, runner):
-        for i in self.children:
-            i.start(runner)
-
-    def is_ready(self):
-        finished = list(itertools.takewhile(
-            lambda i: i.is_ready(), self.unfinished_children))
-        self.unfinished_children.difference_update(finished)
-        return not self.unfinished_children
-
-    def get_result(self):
-        result_list = []
-        exc_info = None
-        for f in self.children:
-            try:
-                result_list.append(f.get_result())
-            except Exception as e:
-                if exc_info is None:
-                    exc_info = sys.exc_info()
-                else:
-                    if not isinstance(e, self.quiet_exceptions):
-                        app_log.error("Multiple exceptions in yield list",
-                                      exc_info=True)
-        if exc_info is not None:
-            raise_exc_info(exc_info)
-        if self.keys is not None:
-            return dict(zip(self.keys, result_list))
-        else:
-            return list(result_list)
-
-
-def multi_future(children, quiet_exceptions=()):
-    """Wait for multiple asynchronous futures in parallel.
-
-    This function is similar to `multi`, but does not support
-    `YieldPoints <YieldPoint>`.
-
-    .. versionadded:: 4.0
-
-    .. versionchanged:: 4.2
-       If multiple ``Futures`` fail, any exceptions after the first (which is
-       raised) will be logged. Added the ``quiet_exceptions``
-       argument to suppress this logging for selected exception types.
-
-    .. deprecated:: 4.3
-       Use `multi` instead.
-    """
-    if isinstance(children, dict):
-        keys = list(children.keys())
-        children = children.values()
-    else:
-        keys = None
-    children = list(map(convert_yielded, children))
-    assert all(is_future(i) for i in children)
-    unfinished_children = set(children)
-
-    future = Future()
-    if not children:
-        future.set_result({} if keys is not None else [])
-
-    def callback(f):
-        unfinished_children.remove(f)
-        if not unfinished_children:
-            result_list = []
-            for f in children:
-                try:
-                    result_list.append(f.result())
-                except Exception as e:
-                    if future.done():
-                        if not isinstance(e, quiet_exceptions):
-                            app_log.error("Multiple exceptions in yield list",
-                                          exc_info=True)
-                    else:
-                        future.set_exc_info(sys.exc_info())
-            if not future.done():
-                if keys is not None:
-                    future.set_result(dict(zip(keys, result_list)))
-                else:
-                    future.set_result(result_list)
-
-    listening = set()
-    for f in children:
-        if f not in listening:
-            listening.add(f)
-            f.add_done_callback(callback)
-    return future
-
-
-def maybe_future(x):
-    """Converts ``x`` into a `.Future`.
-
-    If ``x`` is already a `.Future`, it is simply returned; otherwise
-    it is wrapped in a new `.Future`.  This is suitable for use as
-    ``result = yield gen.maybe_future(f())`` when you don't know whether
-    ``f()`` returns a `.Future` or not.
-
-    .. deprecated:: 4.3
-       This function only handles ``Futures``, not other yieldable objects.
-       Instead of `maybe_future`, check for the non-future result types
-       you expect (often just ``None``), and ``yield`` anything unknown.
-    """
-    if is_future(x):
-        return x
-    else:
-        fut = Future()
-        fut.set_result(x)
-        return fut
-
-
-def with_timeout(timeout, future, io_loop=None, quiet_exceptions=()):
-    """Wraps a `.Future` (or other yieldable object) in a timeout.
-
-    Raises `TimeoutError` if the input future does not complete before
-    ``timeout``, which may be specified in any form allowed by
-    `.IOLoop.add_timeout` (i.e. a `datetime.timedelta` or an absolute time
-    relative to `.IOLoop.time`)
-
-    If the wrapped `.Future` fails after it has timed out, the exception
-    will be logged unless it is of a type contained in ``quiet_exceptions``
-    (which may be an exception type or a sequence of types).
-
-    Does not support `YieldPoint` subclasses.
-
-    .. versionadded:: 4.0
-
-    .. versionchanged:: 4.1
-       Added the ``quiet_exceptions`` argument and the logging of unhandled
-       exceptions.
-
-    .. versionchanged:: 4.4
-       Added support for yieldable objects other than `.Future`.
-    """
-    # TODO: allow YieldPoints in addition to other yieldables?
-    # Tricky to do with stack_context semantics.
-    #
-    # It's tempting to optimize this by cancelling the input future on timeout
-    # instead of creating a new one, but A) we can't know if we are the only
-    # one waiting on the input future, so cancelling it might disrupt other
-    # callers and B) concurrent futures can only be cancelled while they are
-    # in the queue, so cancellation cannot reliably bound our waiting time.
-    future = convert_yielded(future)
-    result = Future()
-    chain_future(future, result)
-    if io_loop is None:
-        io_loop = IOLoop.current()
-
-    def error_callback(future):
-        try:
-            future.result()
-        except Exception as e:
-            if not isinstance(e, quiet_exceptions):
-                app_log.error("Exception in Future %r after timeout",
-                              future, exc_info=True)
-
-    def timeout_callback():
-        if not result.done():
-            result.set_exception(TimeoutError("Timeout"))
-        # In case the wrapped future goes on to fail, log it.
-        future.add_done_callback(error_callback)
-    timeout_handle = io_loop.add_timeout(
-        timeout, timeout_callback)
-    if isinstance(future, Future):
-        # We know this future will resolve on the IOLoop, so we don't
-        # need the extra thread-safety of IOLoop.add_future (and we also
-        # don't care about StackContext here.
-        future.add_done_callback(
-            lambda future: io_loop.remove_timeout(timeout_handle))
-    else:
-        # concurrent.futures.Futures may resolve on any thread, so we
-        # need to route them back to the IOLoop.
-        io_loop.add_future(
-            future, lambda future: io_loop.remove_timeout(timeout_handle))
-    return result
-
-
-def sleep(duration):
-    """Return a `.Future` that resolves after the given number of seconds.
-
-    When used with ``yield`` in a coroutine, this is a non-blocking
-    analogue to `time.sleep` (which should not be used in coroutines
-    because it is blocking)::
-
-        yield gen.sleep(0.5)
-
-    Note that calling this function on its own does nothing; you must
-    wait on the `.Future` it returns (usually by yielding it).
-
-    .. versionadded:: 4.1
-    """
-    f = Future()
-    IOLoop.current().call_later(duration, lambda: f.set_result(None))
-    return f
-
-
-_null_future = Future()
-_null_future.set_result(None)
-
-moment = Future()
-moment.__doc__ = \
-    """A special object which may be yielded to allow the IOLoop to run for
-one iteration.
-
-This is not needed in normal use but it can be helpful in long-running
-coroutines that are likely to yield Futures that are ready instantly.
-
-Usage: ``yield gen.moment``
-
-.. versionadded:: 4.0
-
-.. deprecated:: 4.5
-   ``yield None`` is now equivalent to ``yield gen.moment``.
-"""
-moment.set_result(None)
-
-
-class Runner(object):
-    """Internal implementation of `tornado.gen.engine`.
-
-    Maintains information about pending callbacks and their results.
-
-    The results of the generator are stored in ``result_future`` (a
-    `.TracebackFuture`)
-    """
-    def __init__(self, gen, result_future, first_yielded):
-        self.gen = gen
-        self.result_future = result_future
-        self.future = _null_future
-        self.yield_point = None
-        self.pending_callbacks = None
-        self.results = None
-        self.running = False
-        self.finished = False
-        self.had_exception = False
-        self.io_loop = IOLoop.current()
-        # For efficiency, we do not create a stack context until we
-        # reach a YieldPoint (stack contexts are required for the historical
-        # semantics of YieldPoints, but not for Futures).  When we have
-        # done so, this field will be set and must be called at the end
-        # of the coroutine.
-        self.stack_context_deactivate = None
-        if self.handle_yield(first_yielded):
-            gen = result_future = first_yielded = None
-            self.run()
-
-    def register_callback(self, key):
-        """Adds ``key`` to the list of callbacks."""
-        if self.pending_callbacks is None:
-            # Lazily initialize the old-style YieldPoint data structures.
-            self.pending_callbacks = set()
-            self.results = {}
-        if key in self.pending_callbacks:
-            raise KeyReuseError("key %r is already pending" % (key,))
-        self.pending_callbacks.add(key)
-
-    def is_ready(self, key):
-        """Returns true if a result is available for ``key``."""
-        if self.pending_callbacks is None or key not in self.pending_callbacks:
-            raise UnknownKeyError("key %r is not pending" % (key,))
-        return key in self.results
-
-    def set_result(self, key, result):
-        """Sets the result for ``key`` and attempts to resume the generator."""
-        self.results[key] = result
-        if self.yield_point is not None and self.yield_point.is_ready():
-            try:
-                self.future.set_result(self.yield_point.get_result())
-            except:
-                self.future.set_exc_info(sys.exc_info())
-            self.yield_point = None
-            self.run()
-
-    def pop_result(self, key):
-        """Returns the result for ``key`` and unregisters it."""
-        self.pending_callbacks.remove(key)
-        return self.results.pop(key)
-
-    def run(self):
-        """Starts or resumes the generator, running until it reaches a
-        yield point that is not ready.
-        """
-        if self.running or self.finished:
-            return
-        try:
-            self.running = True
-            while True:
-                future = self.future
-                if not future.done():
-                    return
-                self.future = None
-                try:
-                    orig_stack_contexts = stack_context._state.contexts
-                    exc_info = None
-
-                    try:
-                        value = future.result()
-                    except Exception:
-                        self.had_exception = True
-                        exc_info = sys.exc_info()
-                    future = None
-
-                    if exc_info is not None:
-                        try:
-                            yielded = self.gen.throw(*exc_info)
-                        finally:
-                            # Break up a reference to itself
-                            # for faster GC on CPython.
-                            exc_info = None
-                    else:
-                        yielded = self.gen.send(value)
-
-                    if stack_context._state.contexts is not orig_stack_contexts:
-                        self.gen.throw(
-                            stack_context.StackContextInconsistentError(
-                                'stack_context inconsistency (probably caused '
-                                'by yield within a "with StackContext" block)'))
-                except (StopIteration, Return) as e:
-                    self.finished = True
-                    self.future = _null_future
-                    if self.pending_callbacks and not self.had_exception:
-                        # If we ran cleanly without waiting on all callbacks
-                        # raise an error (really more of a warning).  If we
-                        # had an exception then some callbacks may have been
-                        # orphaned, so skip the check in that case.
-                        raise LeakedCallbackError(
-                            "finished without waiting for callbacks %r" %
-                            self.pending_callbacks)
-                    self.result_future.set_result(_value_from_stopiteration(e))
-                    self.result_future = None
-                    self._deactivate_stack_context()
-                    return
-                except Exception:
-                    self.finished = True
-                    self.future = _null_future
-                    self.result_future.set_exc_info(sys.exc_info())
-                    self.result_future = None
-                    self._deactivate_stack_context()
-                    return
-                if not self.handle_yield(yielded):
-                    return
-                yielded = None
-        finally:
-            self.running = False
-
-    def handle_yield(self, yielded):
-        # Lists containing YieldPoints require stack contexts;
-        # other lists are handled in convert_yielded.
-        if _contains_yieldpoint(yielded):
-            yielded = multi(yielded)
-
-        if isinstance(yielded, YieldPoint):
-            # YieldPoints are too closely coupled to the Runner to go
-            # through the generic convert_yielded mechanism.
-            self.future = TracebackFuture()
-
-            def start_yield_point():
-                try:
-                    yielded.start(self)
-                    if yielded.is_ready():
-                        self.future.set_result(
-                            yielded.get_result())
-                    else:
-                        self.yield_point = yielded
-                except Exception:
-                    self.future = TracebackFuture()
-                    self.future.set_exc_info(sys.exc_info())
-
-            if self.stack_context_deactivate is None:
-                # Start a stack context if this is the first
-                # YieldPoint we've seen.
-                with stack_context.ExceptionStackContext(
-                        self.handle_exception) as deactivate:
-                    self.stack_context_deactivate = deactivate
-
-                    def cb():
-                        start_yield_point()
-                        self.run()
-                    self.io_loop.add_callback(cb)
-                    return False
-            else:
-                start_yield_point()
-        else:
-            try:
-                self.future = convert_yielded(yielded)
-            except BadYieldError:
-                self.future = TracebackFuture()
-                self.future.set_exc_info(sys.exc_info())
-
-        if not self.future.done() or self.future is moment:
-            def inner(f):
-                # Break a reference cycle to speed GC.
-                f = None # noqa
-                self.run()
-            self.io_loop.add_future(
-                self.future, inner)
-            return False
-        return True
-
-    def result_callback(self, key):
-        return stack_context.wrap(_argument_adapter(
-            functools.partial(self.set_result, key)))
-
-    def handle_exception(self, typ, value, tb):
-        if not self.running and not self.finished:
-            self.future = TracebackFuture()
-            self.future.set_exc_info((typ, value, tb))
-            self.run()
-            return True
-        else:
-            return False
-
-    def _deactivate_stack_context(self):
-        if self.stack_context_deactivate is not None:
-            self.stack_context_deactivate()
-            self.stack_context_deactivate = None
-
-
-Arguments = collections.namedtuple('Arguments', ['args', 'kwargs'])
-
-
-def _argument_adapter(callback):
-    """Returns a function that when invoked runs ``callback`` with one arg.
-
-    If the function returned by this function is called with exactly
-    one argument, that argument is passed to ``callback``.  Otherwise
-    the args tuple and kwargs dict are wrapped in an `Arguments` object.
-    """
-    def wrapper(*args, **kwargs):
-        if kwargs or len(args) > 1:
-            callback(Arguments(args, kwargs))
-        elif args:
-            callback(args[0])
-        else:
-            callback(None)
-    return wrapper
-
-
-# Convert Awaitables into Futures. It is unfortunately possible
-# to have infinite recursion here if those Awaitables assume that
-# we're using a different coroutine runner and yield objects
-# we don't understand. If that happens, the solution is to
-# register that runner's yieldable objects with convert_yielded.
-if sys.version_info >= (3, 3):
-    exec(textwrap.dedent("""
-    @coroutine
-    def _wrap_awaitable(x):
-        if hasattr(x, '__await__'):
-            x = x.__await__()
-        return (yield from x)
-    """))
-else:
-    # Py2-compatible version for use with Cython.
-    # Copied from PEP 380.
-    @coroutine
-    def _wrap_awaitable(x):
-        if hasattr(x, '__await__'):
-            _i = x.__await__()
-        else:
-            _i = iter(x)
-        try:
-            _y = next(_i)
-        except StopIteration as _e:
-            _r = _value_from_stopiteration(_e)
-        else:
-            while 1:
-                try:
-                    _s = yield _y
-                except GeneratorExit as _e:
-                    try:
-                        _m = _i.close
-                    except AttributeError:
-                        pass
-                    else:
-                        _m()
-                    raise _e
-                except BaseException as _e:
-                    _x = sys.exc_info()
-                    try:
-                        _m = _i.throw
-                    except AttributeError:
-                        raise _e
-                    else:
-                        try:
-                            _y = _m(*_x)
-                        except StopIteration as _e:
-                            _r = _value_from_stopiteration(_e)
-                            break
-                else:
-                    try:
-                        if _s is None:
-                            _y = next(_i)
-                        else:
-                            _y = _i.send(_s)
-                    except StopIteration as _e:
-                        _r = _value_from_stopiteration(_e)
-                        break
-        raise Return(_r)
-
-
-def convert_yielded(yielded):
-    """Convert a yielded object into a `.Future`.
-
-    The default implementation accepts lists, dictionaries, and Futures.
-
-    If the `~functools.singledispatch` library is available, this function
-    may be extended to support additional types. For example::
-
-        @convert_yielded.register(asyncio.Future)
-        def _(asyncio_future):
-            return tornado.platform.asyncio.to_tornado_future(asyncio_future)
-
-    .. versionadded:: 4.1
-    """
-    # Lists and dicts containing YieldPoints were handled earlier.
-    if yielded is None:
-        return moment
-    elif isinstance(yielded, (list, dict)):
-        return multi(yielded)
-    elif is_future(yielded):
-        return yielded
-    elif isawaitable(yielded):
-        return _wrap_awaitable(yielded)
-    else:
-        raise BadYieldError("yielded unknown object %r" % (yielded,))
-
-
-if singledispatch is not None:
-    convert_yielded = singledispatch(convert_yielded)
-
-    try:
-        # If we can import t.p.asyncio, do it for its side effect
-        # (registering asyncio.Future with convert_yielded).
-        # It's ugly to do this here, but it prevents a cryptic
-        # infinite recursion in _wrap_awaitable.
-        # Note that even with this, asyncio integration is unlikely
-        # to work unless the application also configures AsyncIOLoop,
-        # but at least the error messages in that case are more
-        # comprehensible than a stack overflow.
-        import tornado.platform.asyncio
-    except ImportError:
-        pass
-    else:
-        # Reference the imported module to make pyflakes happy.
-        tornado
+"""``tornado.gen`` is a generator-based interface to make it easier to 
+work in an asynchronous environment.  Code using the ``gen`` module 
+is technically asynchronous, but it is written as a single generator 
+instead of a collection of separate functions. 
+ 
+For example, the following asynchronous handler: 
+ 
+.. testcode:: 
+ 
+    class AsyncHandler(RequestHandler): 
+        @asynchronous 
+        def get(self): 
+            http_client = AsyncHTTPClient() 
+            http_client.fetch("http://example.com", 
+                              callback=self.on_fetch) 
+ 
+        def on_fetch(self, response): 
+            do_something_with_response(response) 
+            self.render("template.html") 
+ 
+.. testoutput:: 
+   :hide: 
+ 
+could be written with ``gen`` as: 
+ 
+.. testcode:: 
+ 
+    class GenAsyncHandler(RequestHandler): 
+        @gen.coroutine 
+        def get(self): 
+            http_client = AsyncHTTPClient() 
+            response = yield http_client.fetch("http://example.com") 
+            do_something_with_response(response) 
+            self.render("template.html") 
+ 
+.. testoutput:: 
+   :hide: 
+ 
+Most asynchronous functions in Tornado return a `.Future`; 
+yielding this object returns its `~.Future.result`. 
+ 
+You can also yield a list or dict of ``Futures``, which will be 
+started at the same time and run in parallel; a list or dict of results will 
+be returned when they are all finished: 
+ 
+.. testcode:: 
+ 
+    @gen.coroutine 
+    def get(self): 
+        http_client = AsyncHTTPClient() 
+        response1, response2 = yield [http_client.fetch(url1), 
+                                      http_client.fetch(url2)] 
+        response_dict = yield dict(response3=http_client.fetch(url3), 
+                                   response4=http_client.fetch(url4)) 
+        response3 = response_dict['response3'] 
+        response4 = response_dict['response4'] 
+ 
+.. testoutput:: 
+   :hide: 
+ 
+If the `~functools.singledispatch` library is available (standard in 
+Python 3.4, available via the `singledispatch 
+<https://pypi.python.org/pypi/singledispatch>`_ package on older 
+versions), additional types of objects may be yielded. Tornado includes 
+support for ``asyncio.Future`` and Twisted's ``Deferred`` class when 
+``tornado.platform.asyncio`` and ``tornado.platform.twisted`` are imported. 
+See the `convert_yielded` function to extend this mechanism. 
+ 
+.. versionchanged:: 3.2 
+   Dict support added. 
+ 
+.. versionchanged:: 4.1 
+   Support added for yielding ``asyncio`` Futures and Twisted Deferreds 
+   via ``singledispatch``. 
+ 
+""" 
+from __future__ import absolute_import, division, print_function 
+ 
+import collections 
+import functools 
+import itertools 
+import os 
+import sys 
+import textwrap 
+import types 
+import weakref 
+ 
+from tornado.concurrent import Future, TracebackFuture, is_future, chain_future 
+from tornado.ioloop import IOLoop 
+from tornado.log import app_log 
+from tornado import stack_context 
+from tornado.util import PY3, raise_exc_info 
+ 
+try: 
+    try: 
+        # py34+ 
+        from functools import singledispatch  # type: ignore 
+    except ImportError: 
+        from singledispatch import singledispatch  # backport 
+except ImportError: 
+    # In most cases, singledispatch is required (to avoid 
+    # difficult-to-diagnose problems in which the functionality 
+    # available differs depending on which invisble packages are 
+    # installed). However, in Google App Engine third-party 
+    # dependencies are more trouble so we allow this module to be 
+    # imported without it. 
+    if 'APPENGINE_RUNTIME' not in os.environ: 
+        raise 
+    singledispatch = None 
+ 
+try: 
+    try: 
+        # py35+ 
+        from collections.abc import Generator as GeneratorType  # type: ignore 
+    except ImportError: 
+        from backports_abc import Generator as GeneratorType  # type: ignore 
+ 
+    try: 
+        # py35+ 
+        from inspect import isawaitable  # type: ignore 
+    except ImportError: 
+        from backports_abc import isawaitable 
+except ImportError: 
+    if 'APPENGINE_RUNTIME' not in os.environ: 
+        raise 
+    from types import GeneratorType 
+ 
+    def isawaitable(x):  # type: ignore 
+        return False 
+ 
+if PY3: 
+    import builtins 
+else: 
+    import __builtin__ as builtins 
+ 
+ 
+class KeyReuseError(Exception): 
+    pass 
+ 
+ 
+class UnknownKeyError(Exception): 
+    pass 
+ 
+ 
+class LeakedCallbackError(Exception): 
+    pass 
+ 
+ 
+class BadYieldError(Exception): 
+    pass 
+ 
+ 
+class ReturnValueIgnoredError(Exception): 
+    pass 
+ 
+ 
+class TimeoutError(Exception): 
+    """Exception raised by ``with_timeout``.""" 
+ 
+ 
+def _value_from_stopiteration(e): 
+    try: 
+        # StopIteration has a value attribute beginning in py33. 
+        # So does our Return class. 
+        return e.value 
+    except AttributeError: 
+        pass 
+    try: 
+        # Cython backports coroutine functionality by putting the value in 
+        # e.args[0]. 
+        return e.args[0] 
+    except (AttributeError, IndexError): 
+        return None 
+ 
+ 
+def engine(func): 
+    """Callback-oriented decorator for asynchronous generators. 
+ 
+    This is an older interface; for new code that does not need to be 
+    compatible with versions of Tornado older than 3.0 the 
+    `coroutine` decorator is recommended instead. 
+ 
+    This decorator is similar to `coroutine`, except it does not 
+    return a `.Future` and the ``callback`` argument is not treated 
+    specially. 
+ 
+    In most cases, functions decorated with `engine` should take 
+    a ``callback`` argument and invoke it with their result when 
+    they are finished.  One notable exception is the 
+    `~tornado.web.RequestHandler` :ref:`HTTP verb methods <verbs>`, 
+    which use ``self.finish()`` in place of a callback argument. 
+    """ 
+    func = _make_coroutine_wrapper(func, replace_callback=False) 
+ 
+    @functools.wraps(func) 
+    def wrapper(*args, **kwargs): 
+        future = func(*args, **kwargs) 
+ 
+        def final_callback(future): 
+            if future.result() is not None: 
+                raise ReturnValueIgnoredError( 
+                    "@gen.engine functions cannot return values: %r" % 
+                    (future.result(),)) 
+        # The engine interface doesn't give us any way to return 
+        # errors but to raise them into the stack context. 
+        # Save the stack context here to use when the Future has resolved. 
+        future.add_done_callback(stack_context.wrap(final_callback)) 
+    return wrapper 
+ 
+ 
+def coroutine(func, replace_callback=True): 
+    """Decorator for asynchronous generators. 
+ 
+    Any generator that yields objects from this module must be wrapped 
+    in either this decorator or `engine`. 
+ 
+    Coroutines may "return" by raising the special exception 
+    `Return(value) <Return>`.  In Python 3.3+, it is also possible for 
+    the function to simply use the ``return value`` statement (prior to 
+    Python 3.3 generators were not allowed to also return values). 
+    In all versions of Python a coroutine that simply wishes to exit 
+    early may use the ``return`` statement without a value. 
+ 
+    Functions with this decorator return a `.Future`.  Additionally, 
+    they may be called with a ``callback`` keyword argument, which 
+    will be invoked with the future's result when it resolves.  If the 
+    coroutine fails, the callback will not be run and an exception 
+    will be raised into the surrounding `.StackContext`.  The 
+    ``callback`` argument is not visible inside the decorated 
+    function; it is handled by the decorator itself. 
+ 
+    From the caller's perspective, ``@gen.coroutine`` is similar to 
+    the combination of ``@return_future`` and ``@gen.engine``. 
+ 
+    .. warning:: 
+ 
+       When exceptions occur inside a coroutine, the exception 
+       information will be stored in the `.Future` object. You must 
+       examine the result of the `.Future` object, or the exception 
+       may go unnoticed by your code. This means yielding the function 
+       if called from another coroutine, using something like 
+       `.IOLoop.run_sync` for top-level calls, or passing the `.Future` 
+       to `.IOLoop.add_future`. 
+ 
+    """ 
+    return _make_coroutine_wrapper(func, replace_callback=True) 
+ 
+ 
+# Ties lifetime of runners to their result futures. Github Issue #1769 
+# Generators, like any object in Python, must be strong referenced 
+# in order to not be cleaned up by the garbage collector. When using 
+# coroutines, the Runner object is what strong-refs the inner 
+# generator. However, the only item that strong-reffed the Runner 
+# was the last Future that the inner generator yielded (via the 
+# Future's internal done_callback list). Usually this is enough, but 
+# it is also possible for this Future to not have any strong references 
+# other than other objects referenced by the Runner object (usually 
+# when using other callback patterns and/or weakrefs). In this 
+# situation, if a garbage collection ran, a cycle would be detected and 
+# Runner objects could be destroyed along with their inner generators 
+# and everything in their local scope. 
+# This map provides strong references to Runner objects as long as 
+# their result future objects also have strong references (typically 
+# from the parent coroutine's Runner). This keeps the coroutine's 
+# Runner alive. 
+_futures_to_runners = weakref.WeakKeyDictionary() 
+ 
+ 
+def _make_coroutine_wrapper(func, replace_callback): 
+    """The inner workings of ``@gen.coroutine`` and ``@gen.engine``. 
+ 
+    The two decorators differ in their treatment of the ``callback`` 
+    argument, so we cannot simply implement ``@engine`` in terms of 
+    ``@coroutine``. 
+    """ 
+    # On Python 3.5, set the coroutine flag on our generator, to allow it 
+    # to be used with 'await'. 
+    wrapped = func 
+    if hasattr(types, 'coroutine'): 
+        func = types.coroutine(func) 
+ 
+    @functools.wraps(wrapped) 
+    def wrapper(*args, **kwargs): 
+        future = TracebackFuture() 
+ 
+        if replace_callback and 'callback' in kwargs: 
+            callback = kwargs.pop('callback') 
+            IOLoop.current().add_future( 
+                future, lambda future: callback(future.result())) 
+ 
+        try: 
+            result = func(*args, **kwargs) 
+        except (Return, StopIteration) as e: 
+            result = _value_from_stopiteration(e) 
+        except Exception: 
+            future.set_exc_info(sys.exc_info()) 
+            return future 
+        else: 
+            if isinstance(result, GeneratorType): 
+                # Inline the first iteration of Runner.run.  This lets us 
+                # avoid the cost of creating a Runner when the coroutine 
+                # never actually yields, which in turn allows us to 
+                # use "optional" coroutines in critical path code without 
+                # performance penalty for the synchronous case. 
+                try: 
+                    orig_stack_contexts = stack_context._state.contexts 
+                    yielded = next(result) 
+                    if stack_context._state.contexts is not orig_stack_contexts: 
+                        yielded = TracebackFuture() 
+                        yielded.set_exception( 
+                            stack_context.StackContextInconsistentError( 
+                                'stack_context inconsistency (probably caused ' 
+                                'by yield within a "with StackContext" block)')) 
+                except (StopIteration, Return) as e: 
+                    future.set_result(_value_from_stopiteration(e)) 
+                except Exception: 
+                    future.set_exc_info(sys.exc_info()) 
+                else: 
+                    _futures_to_runners[future] = Runner(result, future, yielded) 
+                yielded = None 
+                try: 
+                    return future 
+                finally: 
+                    # Subtle memory optimization: if next() raised an exception, 
+                    # the future's exc_info contains a traceback which 
+                    # includes this stack frame.  This creates a cycle, 
+                    # which will be collected at the next full GC but has 
+                    # been shown to greatly increase memory usage of 
+                    # benchmarks (relative to the refcount-based scheme 
+                    # used in the absence of cycles).  We can avoid the 
+                    # cycle by clearing the local variable after we return it. 
+                    future = None 
+        future.set_result(result) 
+        return future 
+ 
+    wrapper.__wrapped__ = wrapped 
+    wrapper.__tornado_coroutine__ = True 
+    return wrapper 
+ 
+ 
+def is_coroutine_function(func): 
+    """Return whether *func* is a coroutine function, i.e. a function 
+    wrapped with `~.gen.coroutine`. 
+ 
+    .. versionadded:: 4.5 
+    """ 
+    return getattr(func, '__tornado_coroutine__', False) 
+ 
+ 
+class Return(Exception): 
+    """Special exception to return a value from a `coroutine`. 
+ 
+    If this exception is raised, its value argument is used as the 
+    result of the coroutine:: 
+ 
+        @gen.coroutine 
+        def fetch_json(url): 
+            response = yield AsyncHTTPClient().fetch(url) 
+            raise gen.Return(json_decode(response.body)) 
+ 
+    In Python 3.3, this exception is no longer necessary: the ``return`` 
+    statement can be used directly to return a value (previously 
+    ``yield`` and ``return`` with a value could not be combined in the 
+    same function). 
+ 
+    By analogy with the return statement, the value argument is optional, 
+    but it is never necessary to ``raise gen.Return()``.  The ``return`` 
+    statement can be used with no arguments instead. 
+    """ 
+    def __init__(self, value=None): 
+        super(Return, self).__init__() 
+        self.value = value 
+        # Cython recognizes subclasses of StopIteration with a .args tuple. 
+        self.args = (value,) 
+ 
+ 
+class WaitIterator(object): 
+    """Provides an iterator to yield the results of futures as they finish. 
+ 
+    Yielding a set of futures like this: 
+ 
+    ``results = yield [future1, future2]`` 
+ 
+    pauses the coroutine until both ``future1`` and ``future2`` 
+    return, and then restarts the coroutine with the results of both 
+    futures. If either future is an exception, the expression will 
+    raise that exception and all the results will be lost. 
+ 
+    If you need to get the result of each future as soon as possible, 
+    or if you need the result of some futures even if others produce 
+    errors, you can use ``WaitIterator``:: 
+ 
+      wait_iterator = gen.WaitIterator(future1, future2) 
+      while not wait_iterator.done(): 
+          try: 
+              result = yield wait_iterator.next() 
+          except Exception as e: 
+              print("Error {} from {}".format(e, wait_iterator.current_future)) 
+          else: 
+              print("Result {} received from {} at {}".format( 
+                  result, wait_iterator.current_future, 
+                  wait_iterator.current_index)) 
+ 
+    Because results are returned as soon as they are available the 
+    output from the iterator *will not be in the same order as the 
+    input arguments*. If you need to know which future produced the 
+    current result, you can use the attributes 
+    ``WaitIterator.current_future``, or ``WaitIterator.current_index`` 
+    to get the index of the future from the input list. (if keyword 
+    arguments were used in the construction of the `WaitIterator`, 
+    ``current_index`` will use the corresponding keyword). 
+ 
+    On Python 3.5, `WaitIterator` implements the async iterator 
+    protocol, so it can be used with the ``async for`` statement (note 
+    that in this version the entire iteration is aborted if any value 
+    raises an exception, while the previous example can continue past 
+    individual errors):: 
+ 
+      async for result in gen.WaitIterator(future1, future2): 
+          print("Result {} received from {} at {}".format( 
+              result, wait_iterator.current_future, 
+              wait_iterator.current_index)) 
+ 
+    .. versionadded:: 4.1 
+ 
+    .. versionchanged:: 4.3 
+       Added ``async for`` support in Python 3.5. 
+ 
+    """ 
+    def __init__(self, *args, **kwargs): 
+        if args and kwargs: 
+            raise ValueError( 
+                "You must provide args or kwargs, not both") 
+ 
+        if kwargs: 
+            self._unfinished = dict((f, k) for (k, f) in kwargs.items()) 
+            futures = list(kwargs.values()) 
+        else: 
+            self._unfinished = dict((f, i) for (i, f) in enumerate(args)) 
+            futures = args 
+ 
+        self._finished = collections.deque() 
+        self.current_index = self.current_future = None 
+        self._running_future = None 
+ 
+        for future in futures: 
+            future.add_done_callback(self._done_callback) 
+ 
+    def done(self): 
+        """Returns True if this iterator has no more results.""" 
+        if self._finished or self._unfinished: 
+            return False 
+        # Clear the 'current' values when iteration is done. 
+        self.current_index = self.current_future = None 
+        return True 
+ 
+    def next(self): 
+        """Returns a `.Future` that will yield the next available result. 
+ 
+        Note that this `.Future` will not be the same object as any of 
+        the inputs. 
+        """ 
+        self._running_future = TracebackFuture() 
+ 
+        if self._finished: 
+            self._return_result(self._finished.popleft()) 
+ 
+        return self._running_future 
+ 
+    def _done_callback(self, done): 
+        if self._running_future and not self._running_future.done(): 
+            self._return_result(done) 
+        else: 
+            self._finished.append(done) 
+ 
+    def _return_result(self, done): 
+        """Called set the returned future's state that of the future 
+        we yielded, and set the current future for the iterator. 
+        """ 
+        chain_future(done, self._running_future) 
+ 
+        self.current_future = done 
+        self.current_index = self._unfinished.pop(done) 
+ 
+    @coroutine 
+    def __aiter__(self): 
+        raise Return(self) 
+ 
+    def __anext__(self): 
+        if self.done(): 
+            # Lookup by name to silence pyflakes on older versions. 
+            raise getattr(builtins, 'StopAsyncIteration')() 
+        return self.next() 
+ 
+ 
+class YieldPoint(object): 
+    """Base class for objects that may be yielded from the generator. 
+ 
+    .. deprecated:: 4.0 
+       Use `Futures <.Future>` instead. 
+    """ 
+    def start(self, runner): 
+        """Called by the runner after the generator has yielded. 
+ 
+        No other methods will be called on this object before ``start``. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def is_ready(self): 
+        """Called by the runner to determine whether to resume the generator. 
+ 
+        Returns a boolean; may be called more than once. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def get_result(self): 
+        """Returns the value to use as the result of the yield expression. 
+ 
+        This method will only be called once, and only after `is_ready` 
+        has returned true. 
+        """ 
+        raise NotImplementedError() 
+ 
+ 
+class Callback(YieldPoint): 
+    """Returns a callable object that will allow a matching `Wait` to proceed. 
+ 
+    The key may be any value suitable for use as a dictionary key, and is 
+    used to match ``Callbacks`` to their corresponding ``Waits``.  The key 
+    must be unique among outstanding callbacks within a single run of the 
+    generator function, but may be reused across different runs of the same 
+    function (so constants generally work fine). 
+ 
+    The callback may be called with zero or one arguments; if an argument 
+    is given it will be returned by `Wait`. 
+ 
+    .. deprecated:: 4.0 
+       Use `Futures <.Future>` instead. 
+    """ 
+    def __init__(self, key): 
+        self.key = key 
+ 
+    def start(self, runner): 
+        self.runner = runner 
+        runner.register_callback(self.key) 
+ 
+    def is_ready(self): 
+        return True 
+ 
+    def get_result(self): 
+        return self.runner.result_callback(self.key) 
+ 
+ 
+class Wait(YieldPoint): 
+    """Returns the argument passed to the result of a previous `Callback`. 
+ 
+    .. deprecated:: 4.0 
+       Use `Futures <.Future>` instead. 
+    """ 
+    def __init__(self, key): 
+        self.key = key 
+ 
+    def start(self, runner): 
+        self.runner = runner 
+ 
+    def is_ready(self): 
+        return self.runner.is_ready(self.key) 
+ 
+    def get_result(self): 
+        return self.runner.pop_result(self.key) 
+ 
+ 
+class WaitAll(YieldPoint): 
+    """Returns the results of multiple previous `Callbacks <Callback>`. 
+ 
+    The argument is a sequence of `Callback` keys, and the result is 
+    a list of results in the same order. 
+ 
+    `WaitAll` is equivalent to yielding a list of `Wait` objects. 
+ 
+    .. deprecated:: 4.0 
+       Use `Futures <.Future>` instead. 
+    """ 
+    def __init__(self, keys): 
+        self.keys = keys 
+ 
+    def start(self, runner): 
+        self.runner = runner 
+ 
+    def is_ready(self): 
+        return all(self.runner.is_ready(key) for key in self.keys) 
+ 
+    def get_result(self): 
+        return [self.runner.pop_result(key) for key in self.keys] 
+ 
+ 
+def Task(func, *args, **kwargs): 
+    """Adapts a callback-based asynchronous function for use in coroutines. 
+ 
+    Takes a function (and optional additional arguments) and runs it with 
+    those arguments plus a ``callback`` keyword argument.  The argument passed 
+    to the callback is returned as the result of the yield expression. 
+ 
+    .. versionchanged:: 4.0 
+       ``gen.Task`` is now a function that returns a `.Future`, instead of 
+       a subclass of `YieldPoint`.  It still behaves the same way when 
+       yielded. 
+    """ 
+    future = Future() 
+ 
+    def handle_exception(typ, value, tb): 
+        if future.done(): 
+            return False 
+        future.set_exc_info((typ, value, tb)) 
+        return True 
+ 
+    def set_result(result): 
+        if future.done(): 
+            return 
+        future.set_result(result) 
+    with stack_context.ExceptionStackContext(handle_exception): 
+        func(*args, callback=_argument_adapter(set_result), **kwargs) 
+    return future 
+ 
+ 
+class YieldFuture(YieldPoint): 
+    def __init__(self, future, io_loop=None): 
+        """Adapts a `.Future` to the `YieldPoint` interface. 
+ 
+        .. versionchanged:: 4.1 
+           The ``io_loop`` argument is deprecated. 
+        """ 
+        self.future = future 
+        self.io_loop = io_loop or IOLoop.current() 
+ 
+    def start(self, runner): 
+        if not self.future.done(): 
+            self.runner = runner 
+            self.key = object() 
+            runner.register_callback(self.key) 
+            self.io_loop.add_future(self.future, runner.result_callback(self.key)) 
+        else: 
+            self.runner = None 
+            self.result_fn = self.future.result 
+ 
+    def is_ready(self): 
+        if self.runner is not None: 
+            return self.runner.is_ready(self.key) 
+        else: 
+            return True 
+ 
+    def get_result(self): 
+        if self.runner is not None: 
+            return self.runner.pop_result(self.key).result() 
+        else: 
+            return self.result_fn() 
+ 
+ 
+def _contains_yieldpoint(children): 
+    """Returns True if ``children`` contains any YieldPoints. 
+ 
+    ``children`` may be a dict or a list, as used by `MultiYieldPoint` 
+    and `multi_future`. 
+    """ 
+    if isinstance(children, dict): 
+        return any(isinstance(i, YieldPoint) for i in children.values()) 
+    if isinstance(children, list): 
+        return any(isinstance(i, YieldPoint) for i in children) 
+    return False 
+ 
+ 
+def multi(children, quiet_exceptions=()): 
+    """Runs multiple asynchronous operations in parallel. 
+ 
+    ``children`` may either be a list or a dict whose values are 
+    yieldable objects. ``multi()`` returns a new yieldable 
+    object that resolves to a parallel structure containing their 
+    results. If ``children`` is a list, the result is a list of 
+    results in the same order; if it is a dict, the result is a dict 
+    with the same keys. 
+ 
+    That is, ``results = yield multi(list_of_futures)`` is equivalent 
+    to:: 
+ 
+        results = [] 
+        for future in list_of_futures: 
+            results.append(yield future) 
+ 
+    If any children raise exceptions, ``multi()`` will raise the first 
+    one. All others will be logged, unless they are of types 
+    contained in the ``quiet_exceptions`` argument. 
+ 
+    If any of the inputs are `YieldPoints <YieldPoint>`, the returned 
+    yieldable object is a `YieldPoint`. Otherwise, returns a `.Future`. 
+    This means that the result of `multi` can be used in a native 
+    coroutine if and only if all of its children can be. 
+ 
+    In a ``yield``-based coroutine, it is not normally necessary to 
+    call this function directly, since the coroutine runner will 
+    do it automatically when a list or dict is yielded. However, 
+    it is necessary in ``await``-based coroutines, or to pass 
+    the ``quiet_exceptions`` argument. 
+ 
+    This function is available under the names ``multi()`` and ``Multi()`` 
+    for historical reasons. 
+ 
+    .. versionchanged:: 4.2 
+       If multiple yieldables fail, any exceptions after the first 
+       (which is raised) will be logged. Added the ``quiet_exceptions`` 
+       argument to suppress this logging for selected exception types. 
+ 
+    .. versionchanged:: 4.3 
+       Replaced the class ``Multi`` and the function ``multi_future`` 
+       with a unified function ``multi``. Added support for yieldables 
+       other than `YieldPoint` and `.Future`. 
+ 
+    """ 
+    if _contains_yieldpoint(children): 
+        return MultiYieldPoint(children, quiet_exceptions=quiet_exceptions) 
+    else: 
+        return multi_future(children, quiet_exceptions=quiet_exceptions) 
+ 
+ 
+Multi = multi 
+ 
+ 
+class MultiYieldPoint(YieldPoint): 
+    """Runs multiple asynchronous operations in parallel. 
+ 
+    This class is similar to `multi`, but it always creates a stack 
+    context even when no children require it. It is not compatible with 
+    native coroutines. 
+ 
+    .. versionchanged:: 4.2 
+       If multiple ``YieldPoints`` fail, any exceptions after the first 
+       (which is raised) will be logged. Added the ``quiet_exceptions`` 
+       argument to suppress this logging for selected exception types. 
+ 
+    .. versionchanged:: 4.3 
+       Renamed from ``Multi`` to ``MultiYieldPoint``. The name ``Multi`` 
+       remains as an alias for the equivalent `multi` function. 
+ 
+    .. deprecated:: 4.3 
+       Use `multi` instead. 
+    """ 
+    def __init__(self, children, quiet_exceptions=()): 
+        self.keys = None 
+        if isinstance(children, dict): 
+            self.keys = list(children.keys()) 
+            children = children.values() 
+        self.children = [] 
+        for i in children: 
+            if not isinstance(i, YieldPoint): 
+                i = convert_yielded(i) 
+            if is_future(i): 
+                i = YieldFuture(i) 
+            self.children.append(i) 
+        assert all(isinstance(i, YieldPoint) for i in self.children) 
+        self.unfinished_children = set(self.children) 
+        self.quiet_exceptions = quiet_exceptions 
+ 
+    def start(self, runner): 
+        for i in self.children: 
+            i.start(runner) 
+ 
+    def is_ready(self): 
+        finished = list(itertools.takewhile( 
+            lambda i: i.is_ready(), self.unfinished_children)) 
+        self.unfinished_children.difference_update(finished) 
+        return not self.unfinished_children 
+ 
+    def get_result(self): 
+        result_list = [] 
+        exc_info = None 
+        for f in self.children: 
+            try: 
+                result_list.append(f.get_result()) 
+            except Exception as e: 
+                if exc_info is None: 
+                    exc_info = sys.exc_info() 
+                else: 
+                    if not isinstance(e, self.quiet_exceptions): 
+                        app_log.error("Multiple exceptions in yield list", 
+                                      exc_info=True) 
+        if exc_info is not None: 
+            raise_exc_info(exc_info) 
+        if self.keys is not None: 
+            return dict(zip(self.keys, result_list)) 
+        else: 
+            return list(result_list) 
+ 
+ 
+def multi_future(children, quiet_exceptions=()): 
+    """Wait for multiple asynchronous futures in parallel. 
+ 
+    This function is similar to `multi`, but does not support 
+    `YieldPoints <YieldPoint>`. 
+ 
+    .. versionadded:: 4.0 
+ 
+    .. versionchanged:: 4.2 
+       If multiple ``Futures`` fail, any exceptions after the first (which is 
+       raised) will be logged. Added the ``quiet_exceptions`` 
+       argument to suppress this logging for selected exception types. 
+ 
+    .. deprecated:: 4.3 
+       Use `multi` instead. 
+    """ 
+    if isinstance(children, dict): 
+        keys = list(children.keys()) 
+        children = children.values() 
+    else: 
+        keys = None 
+    children = list(map(convert_yielded, children)) 
+    assert all(is_future(i) for i in children) 
+    unfinished_children = set(children) 
+ 
+    future = Future() 
+    if not children: 
+        future.set_result({} if keys is not None else []) 
+ 
+    def callback(f): 
+        unfinished_children.remove(f) 
+        if not unfinished_children: 
+            result_list = [] 
+            for f in children: 
+                try: 
+                    result_list.append(f.result()) 
+                except Exception as e: 
+                    if future.done(): 
+                        if not isinstance(e, quiet_exceptions): 
+                            app_log.error("Multiple exceptions in yield list", 
+                                          exc_info=True) 
+                    else: 
+                        future.set_exc_info(sys.exc_info()) 
+            if not future.done(): 
+                if keys is not None: 
+                    future.set_result(dict(zip(keys, result_list))) 
+                else: 
+                    future.set_result(result_list) 
+ 
+    listening = set() 
+    for f in children: 
+        if f not in listening: 
+            listening.add(f) 
+            f.add_done_callback(callback) 
+    return future 
+ 
+ 
+def maybe_future(x): 
+    """Converts ``x`` into a `.Future`. 
+ 
+    If ``x`` is already a `.Future`, it is simply returned; otherwise 
+    it is wrapped in a new `.Future`.  This is suitable for use as 
+    ``result = yield gen.maybe_future(f())`` when you don't know whether 
+    ``f()`` returns a `.Future` or not. 
+ 
+    .. deprecated:: 4.3 
+       This function only handles ``Futures``, not other yieldable objects. 
+       Instead of `maybe_future`, check for the non-future result types 
+       you expect (often just ``None``), and ``yield`` anything unknown. 
+    """ 
+    if is_future(x): 
+        return x 
+    else: 
+        fut = Future() 
+        fut.set_result(x) 
+        return fut 
+ 
+ 
+def with_timeout(timeout, future, io_loop=None, quiet_exceptions=()): 
+    """Wraps a `.Future` (or other yieldable object) in a timeout. 
+ 
+    Raises `TimeoutError` if the input future does not complete before 
+    ``timeout``, which may be specified in any form allowed by 
+    `.IOLoop.add_timeout` (i.e. a `datetime.timedelta` or an absolute time 
+    relative to `.IOLoop.time`) 
+ 
+    If the wrapped `.Future` fails after it has timed out, the exception 
+    will be logged unless it is of a type contained in ``quiet_exceptions`` 
+    (which may be an exception type or a sequence of types). 
+ 
+    Does not support `YieldPoint` subclasses. 
+ 
+    .. versionadded:: 4.0 
+ 
+    .. versionchanged:: 4.1 
+       Added the ``quiet_exceptions`` argument and the logging of unhandled 
+       exceptions. 
+ 
+    .. versionchanged:: 4.4 
+       Added support for yieldable objects other than `.Future`. 
+    """ 
+    # TODO: allow YieldPoints in addition to other yieldables? 
+    # Tricky to do with stack_context semantics. 
+    # 
+    # It's tempting to optimize this by cancelling the input future on timeout 
+    # instead of creating a new one, but A) we can't know if we are the only 
+    # one waiting on the input future, so cancelling it might disrupt other 
+    # callers and B) concurrent futures can only be cancelled while they are 
+    # in the queue, so cancellation cannot reliably bound our waiting time. 
+    future = convert_yielded(future) 
+    result = Future() 
+    chain_future(future, result) 
+    if io_loop is None: 
+        io_loop = IOLoop.current() 
+ 
+    def error_callback(future): 
+        try: 
+            future.result() 
+        except Exception as e: 
+            if not isinstance(e, quiet_exceptions): 
+                app_log.error("Exception in Future %r after timeout", 
+                              future, exc_info=True) 
+ 
+    def timeout_callback(): 
+        if not result.done(): 
+            result.set_exception(TimeoutError("Timeout")) 
+        # In case the wrapped future goes on to fail, log it. 
+        future.add_done_callback(error_callback) 
+    timeout_handle = io_loop.add_timeout( 
+        timeout, timeout_callback) 
+    if isinstance(future, Future): 
+        # We know this future will resolve on the IOLoop, so we don't 
+        # need the extra thread-safety of IOLoop.add_future (and we also 
+        # don't care about StackContext here. 
+        future.add_done_callback( 
+            lambda future: io_loop.remove_timeout(timeout_handle)) 
+    else: 
+        # concurrent.futures.Futures may resolve on any thread, so we 
+        # need to route them back to the IOLoop. 
+        io_loop.add_future( 
+            future, lambda future: io_loop.remove_timeout(timeout_handle)) 
+    return result 
+ 
+ 
+def sleep(duration): 
+    """Return a `.Future` that resolves after the given number of seconds. 
+ 
+    When used with ``yield`` in a coroutine, this is a non-blocking 
+    analogue to `time.sleep` (which should not be used in coroutines 
+    because it is blocking):: 
+ 
+        yield gen.sleep(0.5) 
+ 
+    Note that calling this function on its own does nothing; you must 
+    wait on the `.Future` it returns (usually by yielding it). 
+ 
+    .. versionadded:: 4.1 
+    """ 
+    f = Future() 
+    IOLoop.current().call_later(duration, lambda: f.set_result(None)) 
+    return f 
+ 
+ 
+_null_future = Future() 
+_null_future.set_result(None) 
+ 
+moment = Future() 
+moment.__doc__ = \ 
+    """A special object which may be yielded to allow the IOLoop to run for 
+one iteration. 
+ 
+This is not needed in normal use but it can be helpful in long-running 
+coroutines that are likely to yield Futures that are ready instantly. 
+ 
+Usage: ``yield gen.moment`` 
+ 
+.. versionadded:: 4.0 
+ 
+.. deprecated:: 4.5 
+   ``yield None`` is now equivalent to ``yield gen.moment``. 
+""" 
+moment.set_result(None) 
+ 
+ 
+class Runner(object): 
+    """Internal implementation of `tornado.gen.engine`. 
+ 
+    Maintains information about pending callbacks and their results. 
+ 
+    The results of the generator are stored in ``result_future`` (a 
+    `.TracebackFuture`) 
+    """ 
+    def __init__(self, gen, result_future, first_yielded): 
+        self.gen = gen 
+        self.result_future = result_future 
+        self.future = _null_future 
+        self.yield_point = None 
+        self.pending_callbacks = None 
+        self.results = None 
+        self.running = False 
+        self.finished = False 
+        self.had_exception = False 
+        self.io_loop = IOLoop.current() 
+        # For efficiency, we do not create a stack context until we 
+        # reach a YieldPoint (stack contexts are required for the historical 
+        # semantics of YieldPoints, but not for Futures).  When we have 
+        # done so, this field will be set and must be called at the end 
+        # of the coroutine. 
+        self.stack_context_deactivate = None 
+        if self.handle_yield(first_yielded): 
+            gen = result_future = first_yielded = None 
+            self.run() 
+ 
+    def register_callback(self, key): 
+        """Adds ``key`` to the list of callbacks.""" 
+        if self.pending_callbacks is None: 
+            # Lazily initialize the old-style YieldPoint data structures. 
+            self.pending_callbacks = set() 
+            self.results = {} 
+        if key in self.pending_callbacks: 
+            raise KeyReuseError("key %r is already pending" % (key,)) 
+        self.pending_callbacks.add(key) 
+ 
+    def is_ready(self, key): 
+        """Returns true if a result is available for ``key``.""" 
+        if self.pending_callbacks is None or key not in self.pending_callbacks: 
+            raise UnknownKeyError("key %r is not pending" % (key,)) 
+        return key in self.results 
+ 
+    def set_result(self, key, result): 
+        """Sets the result for ``key`` and attempts to resume the generator.""" 
+        self.results[key] = result 
+        if self.yield_point is not None and self.yield_point.is_ready(): 
+            try: 
+                self.future.set_result(self.yield_point.get_result()) 
+            except: 
+                self.future.set_exc_info(sys.exc_info()) 
+            self.yield_point = None 
+            self.run() 
+ 
+    def pop_result(self, key): 
+        """Returns the result for ``key`` and unregisters it.""" 
+        self.pending_callbacks.remove(key) 
+        return self.results.pop(key) 
+ 
+    def run(self): 
+        """Starts or resumes the generator, running until it reaches a 
+        yield point that is not ready. 
+        """ 
+        if self.running or self.finished: 
+            return 
+        try: 
+            self.running = True 
+            while True: 
+                future = self.future 
+                if not future.done(): 
+                    return 
+                self.future = None 
+                try: 
+                    orig_stack_contexts = stack_context._state.contexts 
+                    exc_info = None 
+ 
+                    try: 
+                        value = future.result() 
+                    except Exception: 
+                        self.had_exception = True 
+                        exc_info = sys.exc_info() 
+                    future = None 
+ 
+                    if exc_info is not None: 
+                        try: 
+                            yielded = self.gen.throw(*exc_info) 
+                        finally: 
+                            # Break up a reference to itself 
+                            # for faster GC on CPython. 
+                            exc_info = None 
+                    else: 
+                        yielded = self.gen.send(value) 
+ 
+                    if stack_context._state.contexts is not orig_stack_contexts: 
+                        self.gen.throw( 
+                            stack_context.StackContextInconsistentError( 
+                                'stack_context inconsistency (probably caused ' 
+                                'by yield within a "with StackContext" block)')) 
+                except (StopIteration, Return) as e: 
+                    self.finished = True 
+                    self.future = _null_future 
+                    if self.pending_callbacks and not self.had_exception: 
+                        # If we ran cleanly without waiting on all callbacks 
+                        # raise an error (really more of a warning).  If we 
+                        # had an exception then some callbacks may have been 
+                        # orphaned, so skip the check in that case. 
+                        raise LeakedCallbackError( 
+                            "finished without waiting for callbacks %r" % 
+                            self.pending_callbacks) 
+                    self.result_future.set_result(_value_from_stopiteration(e)) 
+                    self.result_future = None 
+                    self._deactivate_stack_context() 
+                    return 
+                except Exception: 
+                    self.finished = True 
+                    self.future = _null_future 
+                    self.result_future.set_exc_info(sys.exc_info()) 
+                    self.result_future = None 
+                    self._deactivate_stack_context() 
+                    return 
+                if not self.handle_yield(yielded): 
+                    return 
+                yielded = None 
+        finally: 
+            self.running = False 
+ 
+    def handle_yield(self, yielded): 
+        # Lists containing YieldPoints require stack contexts; 
+        # other lists are handled in convert_yielded. 
+        if _contains_yieldpoint(yielded): 
+            yielded = multi(yielded) 
+ 
+        if isinstance(yielded, YieldPoint): 
+            # YieldPoints are too closely coupled to the Runner to go 
+            # through the generic convert_yielded mechanism. 
+            self.future = TracebackFuture() 
+ 
+            def start_yield_point(): 
+                try: 
+                    yielded.start(self) 
+                    if yielded.is_ready(): 
+                        self.future.set_result( 
+                            yielded.get_result()) 
+                    else: 
+                        self.yield_point = yielded 
+                except Exception: 
+                    self.future = TracebackFuture() 
+                    self.future.set_exc_info(sys.exc_info()) 
+ 
+            if self.stack_context_deactivate is None: 
+                # Start a stack context if this is the first 
+                # YieldPoint we've seen. 
+                with stack_context.ExceptionStackContext( 
+                        self.handle_exception) as deactivate: 
+                    self.stack_context_deactivate = deactivate 
+ 
+                    def cb(): 
+                        start_yield_point() 
+                        self.run() 
+                    self.io_loop.add_callback(cb) 
+                    return False 
+            else: 
+                start_yield_point() 
+        else: 
+            try: 
+                self.future = convert_yielded(yielded) 
+            except BadYieldError: 
+                self.future = TracebackFuture() 
+                self.future.set_exc_info(sys.exc_info()) 
+ 
+        if not self.future.done() or self.future is moment: 
+            def inner(f): 
+                # Break a reference cycle to speed GC. 
+                f = None # noqa 
+                self.run() 
+            self.io_loop.add_future( 
+                self.future, inner) 
+            return False 
+        return True 
+ 
+    def result_callback(self, key): 
+        return stack_context.wrap(_argument_adapter( 
+            functools.partial(self.set_result, key))) 
+ 
+    def handle_exception(self, typ, value, tb): 
+        if not self.running and not self.finished: 
+            self.future = TracebackFuture() 
+            self.future.set_exc_info((typ, value, tb)) 
+            self.run() 
+            return True 
+        else: 
+            return False 
+ 
+    def _deactivate_stack_context(self): 
+        if self.stack_context_deactivate is not None: 
+            self.stack_context_deactivate() 
+            self.stack_context_deactivate = None 
+ 
+ 
+Arguments = collections.namedtuple('Arguments', ['args', 'kwargs']) 
+ 
+ 
+def _argument_adapter(callback): 
+    """Returns a function that when invoked runs ``callback`` with one arg. 
+ 
+    If the function returned by this function is called with exactly 
+    one argument, that argument is passed to ``callback``.  Otherwise 
+    the args tuple and kwargs dict are wrapped in an `Arguments` object. 
+    """ 
+    def wrapper(*args, **kwargs): 
+        if kwargs or len(args) > 1: 
+            callback(Arguments(args, kwargs)) 
+        elif args: 
+            callback(args[0]) 
+        else: 
+            callback(None) 
+    return wrapper 
+ 
+ 
+# Convert Awaitables into Futures. It is unfortunately possible 
+# to have infinite recursion here if those Awaitables assume that 
+# we're using a different coroutine runner and yield objects 
+# we don't understand. If that happens, the solution is to 
+# register that runner's yieldable objects with convert_yielded. 
+if sys.version_info >= (3, 3): 
+    exec(textwrap.dedent(""" 
+    @coroutine 
+    def _wrap_awaitable(x): 
+        if hasattr(x, '__await__'): 
+            x = x.__await__() 
+        return (yield from x) 
+    """)) 
+else: 
+    # Py2-compatible version for use with Cython. 
+    # Copied from PEP 380. 
+    @coroutine 
+    def _wrap_awaitable(x): 
+        if hasattr(x, '__await__'): 
+            _i = x.__await__() 
+        else: 
+            _i = iter(x) 
+        try: 
+            _y = next(_i) 
+        except StopIteration as _e: 
+            _r = _value_from_stopiteration(_e) 
+        else: 
+            while 1: 
+                try: 
+                    _s = yield _y 
+                except GeneratorExit as _e: 
+                    try: 
+                        _m = _i.close 
+                    except AttributeError: 
+                        pass 
+                    else: 
+                        _m() 
+                    raise _e 
+                except BaseException as _e: 
+                    _x = sys.exc_info() 
+                    try: 
+                        _m = _i.throw 
+                    except AttributeError: 
+                        raise _e 
+                    else: 
+                        try: 
+                            _y = _m(*_x) 
+                        except StopIteration as _e: 
+                            _r = _value_from_stopiteration(_e) 
+                            break 
+                else: 
+                    try: 
+                        if _s is None: 
+                            _y = next(_i) 
+                        else: 
+                            _y = _i.send(_s) 
+                    except StopIteration as _e: 
+                        _r = _value_from_stopiteration(_e) 
+                        break 
+        raise Return(_r) 
+ 
+ 
+def convert_yielded(yielded): 
+    """Convert a yielded object into a `.Future`. 
+ 
+    The default implementation accepts lists, dictionaries, and Futures. 
+ 
+    If the `~functools.singledispatch` library is available, this function 
+    may be extended to support additional types. For example:: 
+ 
+        @convert_yielded.register(asyncio.Future) 
+        def _(asyncio_future): 
+            return tornado.platform.asyncio.to_tornado_future(asyncio_future) 
+ 
+    .. versionadded:: 4.1 
+    """ 
+    # Lists and dicts containing YieldPoints were handled earlier. 
+    if yielded is None: 
+        return moment 
+    elif isinstance(yielded, (list, dict)): 
+        return multi(yielded) 
+    elif is_future(yielded): 
+        return yielded 
+    elif isawaitable(yielded): 
+        return _wrap_awaitable(yielded) 
+    else: 
+        raise BadYieldError("yielded unknown object %r" % (yielded,)) 
+ 
+ 
+if singledispatch is not None: 
+    convert_yielded = singledispatch(convert_yielded) 
+ 
+    try: 
+        # If we can import t.p.asyncio, do it for its side effect 
+        # (registering asyncio.Future with convert_yielded). 
+        # It's ugly to do this here, but it prevents a cryptic 
+        # infinite recursion in _wrap_awaitable. 
+        # Note that even with this, asyncio integration is unlikely 
+        # to work unless the application also configures AsyncIOLoop, 
+        # but at least the error messages in that case are more 
+        # comprehensible than a stack overflow. 
+        import tornado.platform.asyncio 
+    except ImportError: 
+        pass 
+    else: 
+        # Reference the imported module to make pyflakes happy. 
+        tornado 
diff --git a/contrib/python/tornado/tornado-4/tornado/http1connection.py b/contrib/python/tornado/tornado-4/tornado/http1connection.py
index 32bed6c961..72e6c3b1f4 100644
--- a/contrib/python/tornado/tornado-4/tornado/http1connection.py
+++ b/contrib/python/tornado/tornado-4/tornado/http1connection.py
@@ -1,742 +1,742 @@
-#!/usr/bin/env python
-#
-# Copyright 2014 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Client and server implementations of HTTP/1.x.
-
-.. versionadded:: 4.0
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import re
-
-from tornado.concurrent import Future
-from tornado.escape import native_str, utf8
-from tornado import gen
-from tornado import httputil
-from tornado import iostream
-from tornado.log import gen_log, app_log
-from tornado import stack_context
-from tornado.util import GzipDecompressor, PY3
-
-
-class _QuietException(Exception):
-    def __init__(self):
-        pass
-
-
-class _ExceptionLoggingContext(object):
-    """Used with the ``with`` statement when calling delegate methods to
-    log any exceptions with the given logger.  Any exceptions caught are
-    converted to _QuietException
-    """
-    def __init__(self, logger):
-        self.logger = logger
-
-    def __enter__(self):
-        pass
-
-    def __exit__(self, typ, value, tb):
-        if value is not None:
-            self.logger.error("Uncaught exception", exc_info=(typ, value, tb))
-            raise _QuietException
-
-
-class HTTP1ConnectionParameters(object):
-    """Parameters for `.HTTP1Connection` and `.HTTP1ServerConnection`.
-    """
-    def __init__(self, no_keep_alive=False, chunk_size=None,
-                 max_header_size=None, header_timeout=None, max_body_size=None,
-                 body_timeout=None, decompress=False):
-        """
-        :arg bool no_keep_alive: If true, always close the connection after
-            one request.
-        :arg int chunk_size: how much data to read into memory at once
-        :arg int max_header_size:  maximum amount of data for HTTP headers
-        :arg float header_timeout: how long to wait for all headers (seconds)
-        :arg int max_body_size: maximum amount of data for body
-        :arg float body_timeout: how long to wait while reading body (seconds)
-        :arg bool decompress: if true, decode incoming
-            ``Content-Encoding: gzip``
-        """
-        self.no_keep_alive = no_keep_alive
-        self.chunk_size = chunk_size or 65536
-        self.max_header_size = max_header_size or 65536
-        self.header_timeout = header_timeout
-        self.max_body_size = max_body_size
-        self.body_timeout = body_timeout
-        self.decompress = decompress
-
-
-class HTTP1Connection(httputil.HTTPConnection):
-    """Implements the HTTP/1.x protocol.
-
-    This class can be on its own for clients, or via `HTTP1ServerConnection`
-    for servers.
-    """
-    def __init__(self, stream, is_client, params=None, context=None):
-        """
-        :arg stream: an `.IOStream`
-        :arg bool is_client: client or server
-        :arg params: a `.HTTP1ConnectionParameters` instance or ``None``
-        :arg context: an opaque application-defined object that can be accessed
-            as ``connection.context``.
-        """
-        self.is_client = is_client
-        self.stream = stream
-        if params is None:
-            params = HTTP1ConnectionParameters()
-        self.params = params
-        self.context = context
-        self.no_keep_alive = params.no_keep_alive
-        # The body limits can be altered by the delegate, so save them
-        # here instead of just referencing self.params later.
-        self._max_body_size = (self.params.max_body_size or
-                               self.stream.max_buffer_size)
-        self._body_timeout = self.params.body_timeout
-        # _write_finished is set to True when finish() has been called,
-        # i.e. there will be no more data sent.  Data may still be in the
-        # stream's write buffer.
-        self._write_finished = False
-        # True when we have read the entire incoming body.
-        self._read_finished = False
-        # _finish_future resolves when all data has been written and flushed
-        # to the IOStream.
-        self._finish_future = Future()
-        # If true, the connection should be closed after this request
-        # (after the response has been written in the server side,
-        # and after it has been read in the client)
-        self._disconnect_on_finish = False
-        self._clear_callbacks()
-        # Save the start lines after we read or write them; they
-        # affect later processing (e.g. 304 responses and HEAD methods
-        # have content-length but no bodies)
-        self._request_start_line = None
-        self._response_start_line = None
-        self._request_headers = None
-        # True if we are writing output with chunked encoding.
-        self._chunking_output = None
-        # While reading a body with a content-length, this is the
-        # amount left to read.
-        self._expected_content_remaining = None
-        # A Future for our outgoing writes, returned by IOStream.write.
-        self._pending_write = None
-
-    def read_response(self, delegate):
-        """Read a single HTTP response.
-
-        Typical client-mode usage is to write a request using `write_headers`,
-        `write`, and `finish`, and then call ``read_response``.
-
-        :arg delegate: a `.HTTPMessageDelegate`
-
-        Returns a `.Future` that resolves to None after the full response has
-        been read.
-        """
-        if self.params.decompress:
-            delegate = _GzipMessageDelegate(delegate, self.params.chunk_size)
-        return self._read_message(delegate)
-
-    @gen.coroutine
-    def _read_message(self, delegate):
-        need_delegate_close = False
-        try:
-            header_future = self.stream.read_until_regex(
-                b"\r?\n\r?\n",
-                max_bytes=self.params.max_header_size)
-            if self.params.header_timeout is None:
-                header_data = yield header_future
-            else:
-                try:
-                    header_data = yield gen.with_timeout(
-                        self.stream.io_loop.time() + self.params.header_timeout,
-                        header_future,
-                        io_loop=self.stream.io_loop,
-                        quiet_exceptions=iostream.StreamClosedError)
-                except gen.TimeoutError:
-                    self.close()
-                    raise gen.Return(False)
-            start_line, headers = self._parse_headers(header_data)
-            if self.is_client:
-                start_line = httputil.parse_response_start_line(start_line)
-                self._response_start_line = start_line
-            else:
-                start_line = httputil.parse_request_start_line(start_line)
-                self._request_start_line = start_line
-                self._request_headers = headers
-
-            self._disconnect_on_finish = not self._can_keep_alive(
-                start_line, headers)
-            need_delegate_close = True
-            with _ExceptionLoggingContext(app_log):
-                header_future = delegate.headers_received(start_line, headers)
-                if header_future is not None:
-                    yield header_future
-            if self.stream is None:
-                # We've been detached.
-                need_delegate_close = False
-                raise gen.Return(False)
-            skip_body = False
-            if self.is_client:
-                if (self._request_start_line is not None and
-                        self._request_start_line.method == 'HEAD'):
-                    skip_body = True
-                code = start_line.code
-                if code == 304:
-                    # 304 responses may include the content-length header
-                    # but do not actually have a body.
-                    # http://tools.ietf.org/html/rfc7230#section-3.3
-                    skip_body = True
-                if code >= 100 and code < 200:
-                    # 1xx responses should never indicate the presence of
-                    # a body.
-                    if ('Content-Length' in headers or
-                            'Transfer-Encoding' in headers):
-                        raise httputil.HTTPInputError(
-                            "Response code %d cannot have body" % code)
-                    # TODO: client delegates will get headers_received twice
-                    # in the case of a 100-continue.  Document or change?
-                    yield self._read_message(delegate)
-            else:
-                if (headers.get("Expect") == "100-continue" and
-                        not self._write_finished):
-                    self.stream.write(b"HTTP/1.1 100 (Continue)\r\n\r\n")
-            if not skip_body:
-                body_future = self._read_body(
-                    start_line.code if self.is_client else 0, headers, delegate)
-                if body_future is not None:
-                    if self._body_timeout is None:
-                        yield body_future
-                    else:
-                        try:
-                            yield gen.with_timeout(
-                                self.stream.io_loop.time() + self._body_timeout,
-                                body_future, self.stream.io_loop,
-                                quiet_exceptions=iostream.StreamClosedError)
-                        except gen.TimeoutError:
-                            gen_log.info("Timeout reading body from %s",
-                                         self.context)
-                            self.stream.close()
-                            raise gen.Return(False)
-            self._read_finished = True
-            if not self._write_finished or self.is_client:
-                need_delegate_close = False
-                with _ExceptionLoggingContext(app_log):
-                    delegate.finish()
-            # If we're waiting for the application to produce an asynchronous
-            # response, and we're not detached, register a close callback
-            # on the stream (we didn't need one while we were reading)
-            if (not self._finish_future.done() and
-                    self.stream is not None and
-                    not self.stream.closed()):
-                self.stream.set_close_callback(self._on_connection_close)
-                yield self._finish_future
-            if self.is_client and self._disconnect_on_finish:
-                self.close()
-            if self.stream is None:
-                raise gen.Return(False)
-        except httputil.HTTPInputError as e:
-            gen_log.info("Malformed HTTP message from %s: %s",
-                         self.context, e)
-            self.close()
-            raise gen.Return(False)
-        finally:
-            if need_delegate_close:
-                with _ExceptionLoggingContext(app_log):
-                    delegate.on_connection_close()
-            header_future = None
-            self._clear_callbacks()
-        raise gen.Return(True)
-
-    def _clear_callbacks(self):
-        """Clears the callback attributes.
-
-        This allows the request handler to be garbage collected more
-        quickly in CPython by breaking up reference cycles.
-        """
-        self._write_callback = None
-        self._write_future = None
-        self._close_callback = None
-        if self.stream is not None:
-            self.stream.set_close_callback(None)
-
-    def set_close_callback(self, callback):
-        """Sets a callback that will be run when the connection is closed.
-
-        .. deprecated:: 4.0
-            Use `.HTTPMessageDelegate.on_connection_close` instead.
-        """
-        self._close_callback = stack_context.wrap(callback)
-
-    def _on_connection_close(self):
-        # Note that this callback is only registered on the IOStream
-        # when we have finished reading the request and are waiting for
-        # the application to produce its response.
-        if self._close_callback is not None:
-            callback = self._close_callback
-            self._close_callback = None
-            callback()
-        if not self._finish_future.done():
-            self._finish_future.set_result(None)
-        self._clear_callbacks()
-
-    def close(self):
-        if self.stream is not None:
-            self.stream.close()
-        self._clear_callbacks()
-        if not self._finish_future.done():
-            self._finish_future.set_result(None)
-
-    def detach(self):
-        """Take control of the underlying stream.
-
-        Returns the underlying `.IOStream` object and stops all further
-        HTTP processing.  May only be called during
-        `.HTTPMessageDelegate.headers_received`.  Intended for implementing
-        protocols like websockets that tunnel over an HTTP handshake.
-        """
-        self._clear_callbacks()
-        stream = self.stream
-        self.stream = None
-        if not self._finish_future.done():
-            self._finish_future.set_result(None)
-        return stream
-
-    def set_body_timeout(self, timeout):
-        """Sets the body timeout for a single request.
-
-        Overrides the value from `.HTTP1ConnectionParameters`.
-        """
-        self._body_timeout = timeout
-
-    def set_max_body_size(self, max_body_size):
-        """Sets the body size limit for a single request.
-
-        Overrides the value from `.HTTP1ConnectionParameters`.
-        """
-        self._max_body_size = max_body_size
-
-    def write_headers(self, start_line, headers, chunk=None, callback=None):
-        """Implements `.HTTPConnection.write_headers`."""
-        lines = []
-        if self.is_client:
-            self._request_start_line = start_line
-            lines.append(utf8('%s %s HTTP/1.1' % (start_line[0], start_line[1])))
-            # Client requests with a non-empty body must have either a
-            # Content-Length or a Transfer-Encoding.
-            self._chunking_output = (
-                start_line.method in ('POST', 'PUT', 'PATCH') and
-                'Content-Length' not in headers and
-                'Transfer-Encoding' not in headers)
-        else:
-            self._response_start_line = start_line
-            lines.append(utf8('HTTP/1.1 %d %s' % (start_line[1], start_line[2])))
-            self._chunking_output = (
-                # TODO: should this use
-                # self._request_start_line.version or
-                # start_line.version?
-                self._request_start_line.version == 'HTTP/1.1' and
-                # 1xx, 204 and 304 responses have no body (not even a zero-length
-                # body), and so should not have either Content-Length or
-                # Transfer-Encoding headers.
-                start_line.code not in (204, 304) and
-                (start_line.code < 100 or start_line.code >= 200) and
-                # No need to chunk the output if a Content-Length is specified.
-                'Content-Length' not in headers and
-                # Applications are discouraged from touching Transfer-Encoding,
-                # but if they do, leave it alone.
-                'Transfer-Encoding' not in headers)
-            # If a 1.0 client asked for keep-alive, add the header.
-            if (self._request_start_line.version == 'HTTP/1.0' and
-                (self._request_headers.get('Connection', '').lower() ==
-                 'keep-alive')):
-                headers['Connection'] = 'Keep-Alive'
-        if self._chunking_output:
-            headers['Transfer-Encoding'] = 'chunked'
-        if (not self.is_client and
-            (self._request_start_line.method == 'HEAD' or
-             start_line.code == 304)):
-            self._expected_content_remaining = 0
-        elif 'Content-Length' in headers:
-            self._expected_content_remaining = int(headers['Content-Length'])
-        else:
-            self._expected_content_remaining = None
-        # TODO: headers are supposed to be of type str, but we still have some
-        # cases that let bytes slip through. Remove these native_str calls when those
-        # are fixed.
-        header_lines = (native_str(n) + ": " + native_str(v) for n, v in headers.get_all())
-        if PY3:
-            lines.extend(l.encode('latin1') for l in header_lines)
-        else:
-            lines.extend(header_lines)
-        for line in lines:
-            if b'\n' in line:
-                raise ValueError('Newline in header: ' + repr(line))
-        future = None
-        if self.stream.closed():
-            future = self._write_future = Future()
-            future.set_exception(iostream.StreamClosedError())
-            future.exception()
-        else:
-            if callback is not None:
-                self._write_callback = stack_context.wrap(callback)
-            else:
-                future = self._write_future = Future()
-            data = b"\r\n".join(lines) + b"\r\n\r\n"
-            if chunk:
-                data += self._format_chunk(chunk)
-            self._pending_write = self.stream.write(data)
-            self._pending_write.add_done_callback(self._on_write_complete)
-        return future
-
-    def _format_chunk(self, chunk):
-        if self._expected_content_remaining is not None:
-            self._expected_content_remaining -= len(chunk)
-            if self._expected_content_remaining < 0:
-                # Close the stream now to stop further framing errors.
-                self.stream.close()
-                raise httputil.HTTPOutputError(
-                    "Tried to write more data than Content-Length")
-        if self._chunking_output and chunk:
-            # Don't write out empty chunks because that means END-OF-STREAM
-            # with chunked encoding
-            return utf8("%x" % len(chunk)) + b"\r\n" + chunk + b"\r\n"
-        else:
-            return chunk
-
-    def write(self, chunk, callback=None):
-        """Implements `.HTTPConnection.write`.
-
-        For backwards compatibility is is allowed but deprecated to
-        skip `write_headers` and instead call `write()` with a
-        pre-encoded header block.
-        """
-        future = None
-        if self.stream.closed():
-            future = self._write_future = Future()
-            self._write_future.set_exception(iostream.StreamClosedError())
-            self._write_future.exception()
-        else:
-            if callback is not None:
-                self._write_callback = stack_context.wrap(callback)
-            else:
-                future = self._write_future = Future()
-            self._pending_write = self.stream.write(self._format_chunk(chunk))
-            self._pending_write.add_done_callback(self._on_write_complete)
-        return future
-
-    def finish(self):
-        """Implements `.HTTPConnection.finish`."""
-        if (self._expected_content_remaining is not None and
-                self._expected_content_remaining != 0 and
-                not self.stream.closed()):
-            self.stream.close()
-            raise httputil.HTTPOutputError(
-                "Tried to write %d bytes less than Content-Length" %
-                self._expected_content_remaining)
-        if self._chunking_output:
-            if not self.stream.closed():
-                self._pending_write = self.stream.write(b"0\r\n\r\n")
-                self._pending_write.add_done_callback(self._on_write_complete)
-        self._write_finished = True
-        # If the app finished the request while we're still reading,
-        # divert any remaining data away from the delegate and
-        # close the connection when we're done sending our response.
-        # Closing the connection is the only way to avoid reading the
-        # whole input body.
-        if not self._read_finished:
-            self._disconnect_on_finish = True
-        # No more data is coming, so instruct TCP to send any remaining
-        # data immediately instead of waiting for a full packet or ack.
-        self.stream.set_nodelay(True)
-        if self._pending_write is None:
-            self._finish_request(None)
-        else:
-            self._pending_write.add_done_callback(self._finish_request)
-
-    def _on_write_complete(self, future):
-        exc = future.exception()
-        if exc is not None and not isinstance(exc, iostream.StreamClosedError):
-            future.result()
-        if self._write_callback is not None:
-            callback = self._write_callback
-            self._write_callback = None
-            self.stream.io_loop.add_callback(callback)
-        if self._write_future is not None:
-            future = self._write_future
-            self._write_future = None
-            future.set_result(None)
-
-    def _can_keep_alive(self, start_line, headers):
-        if self.params.no_keep_alive:
-            return False
-        connection_header = headers.get("Connection")
-        if connection_header is not None:
-            connection_header = connection_header.lower()
-        if start_line.version == "HTTP/1.1":
-            return connection_header != "close"
-        elif ("Content-Length" in headers or
-              headers.get("Transfer-Encoding", "").lower() == "chunked" or
-              getattr(start_line, 'method', None) in ("HEAD", "GET")):
-            # start_line may be a request or response start line; only
-            # the former has a method attribute.
-            return connection_header == "keep-alive"
-        return False
-
-    def _finish_request(self, future):
-        self._clear_callbacks()
-        if not self.is_client and self._disconnect_on_finish:
-            self.close()
-            return
-        # Turn Nagle's algorithm back on, leaving the stream in its
-        # default state for the next request.
-        self.stream.set_nodelay(False)
-        if not self._finish_future.done():
-            self._finish_future.set_result(None)
-
-    def _parse_headers(self, data):
-        # The lstrip removes newlines that some implementations sometimes
-        # insert between messages of a reused connection.  Per RFC 7230,
-        # we SHOULD ignore at least one empty line before the request.
-        # http://tools.ietf.org/html/rfc7230#section-3.5
-        data = native_str(data.decode('latin1')).lstrip("\r\n")
-        # RFC 7230 section allows for both CRLF and bare LF.
-        eol = data.find("\n")
-        start_line = data[:eol].rstrip("\r")
-        try:
-            headers = httputil.HTTPHeaders.parse(data[eol:])
-        except ValueError:
-            # probably form split() if there was no ':' in the line
-            raise httputil.HTTPInputError("Malformed HTTP headers: %r" %
-                                          data[eol:100])
-        return start_line, headers
-
-    def _read_body(self, code, headers, delegate):
-        if "Content-Length" in headers:
-            if "Transfer-Encoding" in headers:
-                # Response cannot contain both Content-Length and
-                # Transfer-Encoding headers.
-                # http://tools.ietf.org/html/rfc7230#section-3.3.3
-                raise httputil.HTTPInputError(
-                    "Response with both Transfer-Encoding and Content-Length")
-            if "," in headers["Content-Length"]:
-                # Proxies sometimes cause Content-Length headers to get
-                # duplicated.  If all the values are identical then we can
-                # use them but if they differ it's an error.
-                pieces = re.split(r',\s*', headers["Content-Length"])
-                if any(i != pieces[0] for i in pieces):
-                    raise httputil.HTTPInputError(
-                        "Multiple unequal Content-Lengths: %r" %
-                        headers["Content-Length"])
-                headers["Content-Length"] = pieces[0]
-
-            try:
-                content_length = int(headers["Content-Length"])
-            except ValueError:
-                # Handles non-integer Content-Length value.
-                raise httputil.HTTPInputError(
-                    "Only integer Content-Length is allowed: %s" % headers["Content-Length"])
-
-            if content_length > self._max_body_size:
-                raise httputil.HTTPInputError("Content-Length too long")
-        else:
-            content_length = None
-
-        if code == 204:
-            # This response code is not allowed to have a non-empty body,
-            # and has an implicit length of zero instead of read-until-close.
-            # http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.3
-            if ("Transfer-Encoding" in headers or
-                    content_length not in (None, 0)):
-                raise httputil.HTTPInputError(
-                    "Response with code %d should not have body" % code)
-            content_length = 0
-
-        if content_length is not None:
-            return self._read_fixed_body(content_length, delegate)
-        if headers.get("Transfer-Encoding", "").lower() == "chunked":
-            return self._read_chunked_body(delegate)
-        if self.is_client:
-            return self._read_body_until_close(delegate)
-        return None
-
-    @gen.coroutine
-    def _read_fixed_body(self, content_length, delegate):
-        while content_length > 0:
-            body = yield self.stream.read_bytes(
-                min(self.params.chunk_size, content_length), partial=True)
-            content_length -= len(body)
-            if not self._write_finished or self.is_client:
-                with _ExceptionLoggingContext(app_log):
-                    ret = delegate.data_received(body)
-                    if ret is not None:
-                        yield ret
-
-    @gen.coroutine
-    def _read_chunked_body(self, delegate):
-        # TODO: "chunk extensions" http://tools.ietf.org/html/rfc2616#section-3.6.1
-        total_size = 0
-        while True:
-            chunk_len = yield self.stream.read_until(b"\r\n", max_bytes=64)
-            chunk_len = int(chunk_len.strip(), 16)
-            if chunk_len == 0:
-                crlf = yield self.stream.read_bytes(2)
-                if crlf != b'\r\n':
-                    raise httputil.HTTPInputError("improperly terminated chunked request")
-                return
-            total_size += chunk_len
-            if total_size > self._max_body_size:
-                raise httputil.HTTPInputError("chunked body too large")
-            bytes_to_read = chunk_len
-            while bytes_to_read:
-                chunk = yield self.stream.read_bytes(
-                    min(bytes_to_read, self.params.chunk_size), partial=True)
-                bytes_to_read -= len(chunk)
-                if not self._write_finished or self.is_client:
-                    with _ExceptionLoggingContext(app_log):
-                        ret = delegate.data_received(chunk)
-                        if ret is not None:
-                            yield ret
-            # chunk ends with \r\n
-            crlf = yield self.stream.read_bytes(2)
-            assert crlf == b"\r\n"
-
-    @gen.coroutine
-    def _read_body_until_close(self, delegate):
-        body = yield self.stream.read_until_close()
-        if not self._write_finished or self.is_client:
-            with _ExceptionLoggingContext(app_log):
-                delegate.data_received(body)
-
-
-class _GzipMessageDelegate(httputil.HTTPMessageDelegate):
-    """Wraps an `HTTPMessageDelegate` to decode ``Content-Encoding: gzip``.
-    """
-    def __init__(self, delegate, chunk_size):
-        self._delegate = delegate
-        self._chunk_size = chunk_size
-        self._decompressor = None
-
-    def headers_received(self, start_line, headers):
-        if headers.get("Content-Encoding") == "gzip":
-            self._decompressor = GzipDecompressor()
-            # Downstream delegates will only see uncompressed data,
-            # so rename the content-encoding header.
-            # (but note that curl_httpclient doesn't do this).
-            headers.add("X-Consumed-Content-Encoding",
-                        headers["Content-Encoding"])
-            del headers["Content-Encoding"]
-        return self._delegate.headers_received(start_line, headers)
-
-    @gen.coroutine
-    def data_received(self, chunk):
-        if self._decompressor:
-            compressed_data = chunk
-            while compressed_data:
-                decompressed = self._decompressor.decompress(
-                    compressed_data, self._chunk_size)
-                if decompressed:
-                    ret = self._delegate.data_received(decompressed)
-                    if ret is not None:
-                        yield ret
-                compressed_data = self._decompressor.unconsumed_tail
-        else:
-            ret = self._delegate.data_received(chunk)
-            if ret is not None:
-                yield ret
-
-    def finish(self):
-        if self._decompressor is not None:
-            tail = self._decompressor.flush()
-            if tail:
-                # I believe the tail will always be empty (i.e.
-                # decompress will return all it can).  The purpose
-                # of the flush call is to detect errors such
-                # as truncated input.  But in case it ever returns
-                # anything, treat it as an extra chunk
-                self._delegate.data_received(tail)
-        return self._delegate.finish()
-
-    def on_connection_close(self):
-        return self._delegate.on_connection_close()
-
-
-class HTTP1ServerConnection(object):
-    """An HTTP/1.x server."""
-    def __init__(self, stream, params=None, context=None):
-        """
-        :arg stream: an `.IOStream`
-        :arg params: a `.HTTP1ConnectionParameters` or None
-        :arg context: an opaque application-defined object that is accessible
-            as ``connection.context``
-        """
-        self.stream = stream
-        if params is None:
-            params = HTTP1ConnectionParameters()
-        self.params = params
-        self.context = context
-        self._serving_future = None
-
-    @gen.coroutine
-    def close(self):
-        """Closes the connection.
-
-        Returns a `.Future` that resolves after the serving loop has exited.
-        """
-        self.stream.close()
-        # Block until the serving loop is done, but ignore any exceptions
-        # (start_serving is already responsible for logging them).
-        try:
-            yield self._serving_future
-        except Exception:
-            pass
-
-    def start_serving(self, delegate):
-        """Starts serving requests on this connection.
-
-        :arg delegate: a `.HTTPServerConnectionDelegate`
-        """
-        assert isinstance(delegate, httputil.HTTPServerConnectionDelegate)
-        self._serving_future = self._server_request_loop(delegate)
-        # Register the future on the IOLoop so its errors get logged.
-        self.stream.io_loop.add_future(self._serving_future,
-                                       lambda f: f.result())
-
-    @gen.coroutine
-    def _server_request_loop(self, delegate):
-        try:
-            while True:
-                conn = HTTP1Connection(self.stream, False,
-                                       self.params, self.context)
-                request_delegate = delegate.start_request(self, conn)
-                try:
-                    ret = yield conn.read_response(request_delegate)
-                except (iostream.StreamClosedError,
-                        iostream.UnsatisfiableReadError):
-                    return
-                except _QuietException:
-                    # This exception was already logged.
-                    conn.close()
-                    return
-                except Exception:
-                    gen_log.error("Uncaught exception", exc_info=True)
-                    conn.close()
-                    return
-                if not ret:
-                    return
-                yield gen.moment
-        finally:
-            delegate.on_close(self)
+#!/usr/bin/env python 
+# 
+# Copyright 2014 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Client and server implementations of HTTP/1.x. 
+ 
+.. versionadded:: 4.0 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import re 
+ 
+from tornado.concurrent import Future 
+from tornado.escape import native_str, utf8 
+from tornado import gen 
+from tornado import httputil 
+from tornado import iostream 
+from tornado.log import gen_log, app_log 
+from tornado import stack_context 
+from tornado.util import GzipDecompressor, PY3 
+ 
+ 
+class _QuietException(Exception): 
+    def __init__(self): 
+        pass 
+ 
+ 
+class _ExceptionLoggingContext(object): 
+    """Used with the ``with`` statement when calling delegate methods to 
+    log any exceptions with the given logger.  Any exceptions caught are 
+    converted to _QuietException 
+    """ 
+    def __init__(self, logger): 
+        self.logger = logger 
+ 
+    def __enter__(self): 
+        pass 
+ 
+    def __exit__(self, typ, value, tb): 
+        if value is not None: 
+            self.logger.error("Uncaught exception", exc_info=(typ, value, tb)) 
+            raise _QuietException 
+ 
+ 
+class HTTP1ConnectionParameters(object): 
+    """Parameters for `.HTTP1Connection` and `.HTTP1ServerConnection`. 
+    """ 
+    def __init__(self, no_keep_alive=False, chunk_size=None, 
+                 max_header_size=None, header_timeout=None, max_body_size=None, 
+                 body_timeout=None, decompress=False): 
+        """ 
+        :arg bool no_keep_alive: If true, always close the connection after 
+            one request. 
+        :arg int chunk_size: how much data to read into memory at once 
+        :arg int max_header_size:  maximum amount of data for HTTP headers 
+        :arg float header_timeout: how long to wait for all headers (seconds) 
+        :arg int max_body_size: maximum amount of data for body 
+        :arg float body_timeout: how long to wait while reading body (seconds) 
+        :arg bool decompress: if true, decode incoming 
+            ``Content-Encoding: gzip`` 
+        """ 
+        self.no_keep_alive = no_keep_alive 
+        self.chunk_size = chunk_size or 65536 
+        self.max_header_size = max_header_size or 65536 
+        self.header_timeout = header_timeout 
+        self.max_body_size = max_body_size 
+        self.body_timeout = body_timeout 
+        self.decompress = decompress 
+ 
+ 
+class HTTP1Connection(httputil.HTTPConnection): 
+    """Implements the HTTP/1.x protocol. 
+ 
+    This class can be on its own for clients, or via `HTTP1ServerConnection` 
+    for servers. 
+    """ 
+    def __init__(self, stream, is_client, params=None, context=None): 
+        """ 
+        :arg stream: an `.IOStream` 
+        :arg bool is_client: client or server 
+        :arg params: a `.HTTP1ConnectionParameters` instance or ``None`` 
+        :arg context: an opaque application-defined object that can be accessed 
+            as ``connection.context``. 
+        """ 
+        self.is_client = is_client 
+        self.stream = stream 
+        if params is None: 
+            params = HTTP1ConnectionParameters() 
+        self.params = params 
+        self.context = context 
+        self.no_keep_alive = params.no_keep_alive 
+        # The body limits can be altered by the delegate, so save them 
+        # here instead of just referencing self.params later. 
+        self._max_body_size = (self.params.max_body_size or 
+                               self.stream.max_buffer_size) 
+        self._body_timeout = self.params.body_timeout 
+        # _write_finished is set to True when finish() has been called, 
+        # i.e. there will be no more data sent.  Data may still be in the 
+        # stream's write buffer. 
+        self._write_finished = False 
+        # True when we have read the entire incoming body. 
+        self._read_finished = False 
+        # _finish_future resolves when all data has been written and flushed 
+        # to the IOStream. 
+        self._finish_future = Future() 
+        # If true, the connection should be closed after this request 
+        # (after the response has been written in the server side, 
+        # and after it has been read in the client) 
+        self._disconnect_on_finish = False 
+        self._clear_callbacks() 
+        # Save the start lines after we read or write them; they 
+        # affect later processing (e.g. 304 responses and HEAD methods 
+        # have content-length but no bodies) 
+        self._request_start_line = None 
+        self._response_start_line = None 
+        self._request_headers = None 
+        # True if we are writing output with chunked encoding. 
+        self._chunking_output = None 
+        # While reading a body with a content-length, this is the 
+        # amount left to read. 
+        self._expected_content_remaining = None 
+        # A Future for our outgoing writes, returned by IOStream.write. 
+        self._pending_write = None 
+ 
+    def read_response(self, delegate): 
+        """Read a single HTTP response. 
+ 
+        Typical client-mode usage is to write a request using `write_headers`, 
+        `write`, and `finish`, and then call ``read_response``. 
+ 
+        :arg delegate: a `.HTTPMessageDelegate` 
+ 
+        Returns a `.Future` that resolves to None after the full response has 
+        been read. 
+        """ 
+        if self.params.decompress: 
+            delegate = _GzipMessageDelegate(delegate, self.params.chunk_size) 
+        return self._read_message(delegate) 
+ 
+    @gen.coroutine 
+    def _read_message(self, delegate): 
+        need_delegate_close = False 
+        try: 
+            header_future = self.stream.read_until_regex( 
+                b"\r?\n\r?\n", 
+                max_bytes=self.params.max_header_size) 
+            if self.params.header_timeout is None: 
+                header_data = yield header_future 
+            else: 
+                try: 
+                    header_data = yield gen.with_timeout( 
+                        self.stream.io_loop.time() + self.params.header_timeout, 
+                        header_future, 
+                        io_loop=self.stream.io_loop, 
+                        quiet_exceptions=iostream.StreamClosedError) 
+                except gen.TimeoutError: 
+                    self.close() 
+                    raise gen.Return(False) 
+            start_line, headers = self._parse_headers(header_data) 
+            if self.is_client: 
+                start_line = httputil.parse_response_start_line(start_line) 
+                self._response_start_line = start_line 
+            else: 
+                start_line = httputil.parse_request_start_line(start_line) 
+                self._request_start_line = start_line 
+                self._request_headers = headers 
+ 
+            self._disconnect_on_finish = not self._can_keep_alive( 
+                start_line, headers) 
+            need_delegate_close = True 
+            with _ExceptionLoggingContext(app_log): 
+                header_future = delegate.headers_received(start_line, headers) 
+                if header_future is not None: 
+                    yield header_future 
+            if self.stream is None: 
+                # We've been detached. 
+                need_delegate_close = False 
+                raise gen.Return(False) 
+            skip_body = False 
+            if self.is_client: 
+                if (self._request_start_line is not None and 
+                        self._request_start_line.method == 'HEAD'): 
+                    skip_body = True 
+                code = start_line.code 
+                if code == 304: 
+                    # 304 responses may include the content-length header 
+                    # but do not actually have a body. 
+                    # http://tools.ietf.org/html/rfc7230#section-3.3 
+                    skip_body = True 
+                if code >= 100 and code < 200: 
+                    # 1xx responses should never indicate the presence of 
+                    # a body. 
+                    if ('Content-Length' in headers or 
+                            'Transfer-Encoding' in headers): 
+                        raise httputil.HTTPInputError( 
+                            "Response code %d cannot have body" % code) 
+                    # TODO: client delegates will get headers_received twice 
+                    # in the case of a 100-continue.  Document or change? 
+                    yield self._read_message(delegate) 
+            else: 
+                if (headers.get("Expect") == "100-continue" and 
+                        not self._write_finished): 
+                    self.stream.write(b"HTTP/1.1 100 (Continue)\r\n\r\n") 
+            if not skip_body: 
+                body_future = self._read_body( 
+                    start_line.code if self.is_client else 0, headers, delegate) 
+                if body_future is not None: 
+                    if self._body_timeout is None: 
+                        yield body_future 
+                    else: 
+                        try: 
+                            yield gen.with_timeout( 
+                                self.stream.io_loop.time() + self._body_timeout, 
+                                body_future, self.stream.io_loop, 
+                                quiet_exceptions=iostream.StreamClosedError) 
+                        except gen.TimeoutError: 
+                            gen_log.info("Timeout reading body from %s", 
+                                         self.context) 
+                            self.stream.close() 
+                            raise gen.Return(False) 
+            self._read_finished = True 
+            if not self._write_finished or self.is_client: 
+                need_delegate_close = False 
+                with _ExceptionLoggingContext(app_log): 
+                    delegate.finish() 
+            # If we're waiting for the application to produce an asynchronous 
+            # response, and we're not detached, register a close callback 
+            # on the stream (we didn't need one while we were reading) 
+            if (not self._finish_future.done() and 
+                    self.stream is not None and 
+                    not self.stream.closed()): 
+                self.stream.set_close_callback(self._on_connection_close) 
+                yield self._finish_future 
+            if self.is_client and self._disconnect_on_finish: 
+                self.close() 
+            if self.stream is None: 
+                raise gen.Return(False) 
+        except httputil.HTTPInputError as e: 
+            gen_log.info("Malformed HTTP message from %s: %s", 
+                         self.context, e) 
+            self.close() 
+            raise gen.Return(False) 
+        finally: 
+            if need_delegate_close: 
+                with _ExceptionLoggingContext(app_log): 
+                    delegate.on_connection_close() 
+            header_future = None 
+            self._clear_callbacks() 
+        raise gen.Return(True) 
+ 
+    def _clear_callbacks(self): 
+        """Clears the callback attributes. 
+ 
+        This allows the request handler to be garbage collected more 
+        quickly in CPython by breaking up reference cycles. 
+        """ 
+        self._write_callback = None 
+        self._write_future = None 
+        self._close_callback = None 
+        if self.stream is not None: 
+            self.stream.set_close_callback(None) 
+ 
+    def set_close_callback(self, callback): 
+        """Sets a callback that will be run when the connection is closed. 
+ 
+        .. deprecated:: 4.0 
+            Use `.HTTPMessageDelegate.on_connection_close` instead. 
+        """ 
+        self._close_callback = stack_context.wrap(callback) 
+ 
+    def _on_connection_close(self): 
+        # Note that this callback is only registered on the IOStream 
+        # when we have finished reading the request and are waiting for 
+        # the application to produce its response. 
+        if self._close_callback is not None: 
+            callback = self._close_callback 
+            self._close_callback = None 
+            callback() 
+        if not self._finish_future.done(): 
+            self._finish_future.set_result(None) 
+        self._clear_callbacks() 
+ 
+    def close(self): 
+        if self.stream is not None: 
+            self.stream.close() 
+        self._clear_callbacks() 
+        if not self._finish_future.done(): 
+            self._finish_future.set_result(None) 
+ 
+    def detach(self): 
+        """Take control of the underlying stream. 
+ 
+        Returns the underlying `.IOStream` object and stops all further 
+        HTTP processing.  May only be called during 
+        `.HTTPMessageDelegate.headers_received`.  Intended for implementing 
+        protocols like websockets that tunnel over an HTTP handshake. 
+        """ 
+        self._clear_callbacks() 
+        stream = self.stream 
+        self.stream = None 
+        if not self._finish_future.done(): 
+            self._finish_future.set_result(None) 
+        return stream 
+ 
+    def set_body_timeout(self, timeout): 
+        """Sets the body timeout for a single request. 
+ 
+        Overrides the value from `.HTTP1ConnectionParameters`. 
+        """ 
+        self._body_timeout = timeout 
+ 
+    def set_max_body_size(self, max_body_size): 
+        """Sets the body size limit for a single request. 
+ 
+        Overrides the value from `.HTTP1ConnectionParameters`. 
+        """ 
+        self._max_body_size = max_body_size 
+ 
+    def write_headers(self, start_line, headers, chunk=None, callback=None): 
+        """Implements `.HTTPConnection.write_headers`.""" 
+        lines = [] 
+        if self.is_client: 
+            self._request_start_line = start_line 
+            lines.append(utf8('%s %s HTTP/1.1' % (start_line[0], start_line[1]))) 
+            # Client requests with a non-empty body must have either a 
+            # Content-Length or a Transfer-Encoding. 
+            self._chunking_output = ( 
+                start_line.method in ('POST', 'PUT', 'PATCH') and 
+                'Content-Length' not in headers and 
+                'Transfer-Encoding' not in headers) 
+        else: 
+            self._response_start_line = start_line 
+            lines.append(utf8('HTTP/1.1 %d %s' % (start_line[1], start_line[2]))) 
+            self._chunking_output = ( 
+                # TODO: should this use 
+                # self._request_start_line.version or 
+                # start_line.version? 
+                self._request_start_line.version == 'HTTP/1.1' and 
+                # 1xx, 204 and 304 responses have no body (not even a zero-length 
+                # body), and so should not have either Content-Length or 
+                # Transfer-Encoding headers. 
+                start_line.code not in (204, 304) and 
+                (start_line.code < 100 or start_line.code >= 200) and 
+                # No need to chunk the output if a Content-Length is specified. 
+                'Content-Length' not in headers and 
+                # Applications are discouraged from touching Transfer-Encoding, 
+                # but if they do, leave it alone. 
+                'Transfer-Encoding' not in headers) 
+            # If a 1.0 client asked for keep-alive, add the header. 
+            if (self._request_start_line.version == 'HTTP/1.0' and 
+                (self._request_headers.get('Connection', '').lower() == 
+                 'keep-alive')): 
+                headers['Connection'] = 'Keep-Alive' 
+        if self._chunking_output: 
+            headers['Transfer-Encoding'] = 'chunked' 
+        if (not self.is_client and 
+            (self._request_start_line.method == 'HEAD' or 
+             start_line.code == 304)): 
+            self._expected_content_remaining = 0 
+        elif 'Content-Length' in headers: 
+            self._expected_content_remaining = int(headers['Content-Length']) 
+        else: 
+            self._expected_content_remaining = None 
+        # TODO: headers are supposed to be of type str, but we still have some 
+        # cases that let bytes slip through. Remove these native_str calls when those 
+        # are fixed. 
+        header_lines = (native_str(n) + ": " + native_str(v) for n, v in headers.get_all()) 
+        if PY3: 
+            lines.extend(l.encode('latin1') for l in header_lines) 
+        else: 
+            lines.extend(header_lines) 
+        for line in lines: 
+            if b'\n' in line: 
+                raise ValueError('Newline in header: ' + repr(line)) 
+        future = None 
+        if self.stream.closed(): 
+            future = self._write_future = Future() 
+            future.set_exception(iostream.StreamClosedError()) 
+            future.exception() 
+        else: 
+            if callback is not None: 
+                self._write_callback = stack_context.wrap(callback) 
+            else: 
+                future = self._write_future = Future() 
+            data = b"\r\n".join(lines) + b"\r\n\r\n" 
+            if chunk: 
+                data += self._format_chunk(chunk) 
+            self._pending_write = self.stream.write(data) 
+            self._pending_write.add_done_callback(self._on_write_complete) 
+        return future 
+ 
+    def _format_chunk(self, chunk): 
+        if self._expected_content_remaining is not None: 
+            self._expected_content_remaining -= len(chunk) 
+            if self._expected_content_remaining < 0: 
+                # Close the stream now to stop further framing errors. 
+                self.stream.close() 
+                raise httputil.HTTPOutputError( 
+                    "Tried to write more data than Content-Length") 
+        if self._chunking_output and chunk: 
+            # Don't write out empty chunks because that means END-OF-STREAM 
+            # with chunked encoding 
+            return utf8("%x" % len(chunk)) + b"\r\n" + chunk + b"\r\n" 
+        else: 
+            return chunk 
+ 
+    def write(self, chunk, callback=None): 
+        """Implements `.HTTPConnection.write`. 
+ 
+        For backwards compatibility is is allowed but deprecated to 
+        skip `write_headers` and instead call `write()` with a 
+        pre-encoded header block. 
+        """ 
+        future = None 
+        if self.stream.closed(): 
+            future = self._write_future = Future() 
+            self._write_future.set_exception(iostream.StreamClosedError()) 
+            self._write_future.exception() 
+        else: 
+            if callback is not None: 
+                self._write_callback = stack_context.wrap(callback) 
+            else: 
+                future = self._write_future = Future() 
+            self._pending_write = self.stream.write(self._format_chunk(chunk)) 
+            self._pending_write.add_done_callback(self._on_write_complete) 
+        return future 
+ 
+    def finish(self): 
+        """Implements `.HTTPConnection.finish`.""" 
+        if (self._expected_content_remaining is not None and 
+                self._expected_content_remaining != 0 and 
+                not self.stream.closed()): 
+            self.stream.close() 
+            raise httputil.HTTPOutputError( 
+                "Tried to write %d bytes less than Content-Length" % 
+                self._expected_content_remaining) 
+        if self._chunking_output: 
+            if not self.stream.closed(): 
+                self._pending_write = self.stream.write(b"0\r\n\r\n") 
+                self._pending_write.add_done_callback(self._on_write_complete) 
+        self._write_finished = True 
+        # If the app finished the request while we're still reading, 
+        # divert any remaining data away from the delegate and 
+        # close the connection when we're done sending our response. 
+        # Closing the connection is the only way to avoid reading the 
+        # whole input body. 
+        if not self._read_finished: 
+            self._disconnect_on_finish = True 
+        # No more data is coming, so instruct TCP to send any remaining 
+        # data immediately instead of waiting for a full packet or ack. 
+        self.stream.set_nodelay(True) 
+        if self._pending_write is None: 
+            self._finish_request(None) 
+        else: 
+            self._pending_write.add_done_callback(self._finish_request) 
+ 
+    def _on_write_complete(self, future): 
+        exc = future.exception() 
+        if exc is not None and not isinstance(exc, iostream.StreamClosedError): 
+            future.result() 
+        if self._write_callback is not None: 
+            callback = self._write_callback 
+            self._write_callback = None 
+            self.stream.io_loop.add_callback(callback) 
+        if self._write_future is not None: 
+            future = self._write_future 
+            self._write_future = None 
+            future.set_result(None) 
+ 
+    def _can_keep_alive(self, start_line, headers): 
+        if self.params.no_keep_alive: 
+            return False 
+        connection_header = headers.get("Connection") 
+        if connection_header is not None: 
+            connection_header = connection_header.lower() 
+        if start_line.version == "HTTP/1.1": 
+            return connection_header != "close" 
+        elif ("Content-Length" in headers or 
+              headers.get("Transfer-Encoding", "").lower() == "chunked" or 
+              getattr(start_line, 'method', None) in ("HEAD", "GET")): 
+            # start_line may be a request or response start line; only 
+            # the former has a method attribute. 
+            return connection_header == "keep-alive" 
+        return False 
+ 
+    def _finish_request(self, future): 
+        self._clear_callbacks() 
+        if not self.is_client and self._disconnect_on_finish: 
+            self.close() 
+            return 
+        # Turn Nagle's algorithm back on, leaving the stream in its 
+        # default state for the next request. 
+        self.stream.set_nodelay(False) 
+        if not self._finish_future.done(): 
+            self._finish_future.set_result(None) 
+ 
+    def _parse_headers(self, data): 
+        # The lstrip removes newlines that some implementations sometimes 
+        # insert between messages of a reused connection.  Per RFC 7230, 
+        # we SHOULD ignore at least one empty line before the request. 
+        # http://tools.ietf.org/html/rfc7230#section-3.5 
+        data = native_str(data.decode('latin1')).lstrip("\r\n") 
+        # RFC 7230 section allows for both CRLF and bare LF. 
+        eol = data.find("\n") 
+        start_line = data[:eol].rstrip("\r") 
+        try: 
+            headers = httputil.HTTPHeaders.parse(data[eol:]) 
+        except ValueError: 
+            # probably form split() if there was no ':' in the line 
+            raise httputil.HTTPInputError("Malformed HTTP headers: %r" % 
+                                          data[eol:100]) 
+        return start_line, headers 
+ 
+    def _read_body(self, code, headers, delegate): 
+        if "Content-Length" in headers: 
+            if "Transfer-Encoding" in headers: 
+                # Response cannot contain both Content-Length and 
+                # Transfer-Encoding headers. 
+                # http://tools.ietf.org/html/rfc7230#section-3.3.3 
+                raise httputil.HTTPInputError( 
+                    "Response with both Transfer-Encoding and Content-Length") 
+            if "," in headers["Content-Length"]: 
+                # Proxies sometimes cause Content-Length headers to get 
+                # duplicated.  If all the values are identical then we can 
+                # use them but if they differ it's an error. 
+                pieces = re.split(r',\s*', headers["Content-Length"]) 
+                if any(i != pieces[0] for i in pieces): 
+                    raise httputil.HTTPInputError( 
+                        "Multiple unequal Content-Lengths: %r" % 
+                        headers["Content-Length"]) 
+                headers["Content-Length"] = pieces[0] 
+ 
+            try: 
+                content_length = int(headers["Content-Length"]) 
+            except ValueError: 
+                # Handles non-integer Content-Length value. 
+                raise httputil.HTTPInputError( 
+                    "Only integer Content-Length is allowed: %s" % headers["Content-Length"]) 
+ 
+            if content_length > self._max_body_size: 
+                raise httputil.HTTPInputError("Content-Length too long") 
+        else: 
+            content_length = None 
+ 
+        if code == 204: 
+            # This response code is not allowed to have a non-empty body, 
+            # and has an implicit length of zero instead of read-until-close. 
+            # http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.3 
+            if ("Transfer-Encoding" in headers or 
+                    content_length not in (None, 0)): 
+                raise httputil.HTTPInputError( 
+                    "Response with code %d should not have body" % code) 
+            content_length = 0 
+ 
+        if content_length is not None: 
+            return self._read_fixed_body(content_length, delegate) 
+        if headers.get("Transfer-Encoding", "").lower() == "chunked": 
+            return self._read_chunked_body(delegate) 
+        if self.is_client: 
+            return self._read_body_until_close(delegate) 
+        return None 
+ 
+    @gen.coroutine 
+    def _read_fixed_body(self, content_length, delegate): 
+        while content_length > 0: 
+            body = yield self.stream.read_bytes( 
+                min(self.params.chunk_size, content_length), partial=True) 
+            content_length -= len(body) 
+            if not self._write_finished or self.is_client: 
+                with _ExceptionLoggingContext(app_log): 
+                    ret = delegate.data_received(body) 
+                    if ret is not None: 
+                        yield ret 
+ 
+    @gen.coroutine 
+    def _read_chunked_body(self, delegate): 
+        # TODO: "chunk extensions" http://tools.ietf.org/html/rfc2616#section-3.6.1 
+        total_size = 0 
+        while True: 
+            chunk_len = yield self.stream.read_until(b"\r\n", max_bytes=64) 
+            chunk_len = int(chunk_len.strip(), 16) 
+            if chunk_len == 0: 
+                crlf = yield self.stream.read_bytes(2) 
+                if crlf != b'\r\n': 
+                    raise httputil.HTTPInputError("improperly terminated chunked request") 
+                return 
+            total_size += chunk_len 
+            if total_size > self._max_body_size: 
+                raise httputil.HTTPInputError("chunked body too large") 
+            bytes_to_read = chunk_len 
+            while bytes_to_read: 
+                chunk = yield self.stream.read_bytes( 
+                    min(bytes_to_read, self.params.chunk_size), partial=True) 
+                bytes_to_read -= len(chunk) 
+                if not self._write_finished or self.is_client: 
+                    with _ExceptionLoggingContext(app_log): 
+                        ret = delegate.data_received(chunk) 
+                        if ret is not None: 
+                            yield ret 
+            # chunk ends with \r\n 
+            crlf = yield self.stream.read_bytes(2) 
+            assert crlf == b"\r\n" 
+ 
+    @gen.coroutine 
+    def _read_body_until_close(self, delegate): 
+        body = yield self.stream.read_until_close() 
+        if not self._write_finished or self.is_client: 
+            with _ExceptionLoggingContext(app_log): 
+                delegate.data_received(body) 
+ 
+ 
+class _GzipMessageDelegate(httputil.HTTPMessageDelegate): 
+    """Wraps an `HTTPMessageDelegate` to decode ``Content-Encoding: gzip``. 
+    """ 
+    def __init__(self, delegate, chunk_size): 
+        self._delegate = delegate 
+        self._chunk_size = chunk_size 
+        self._decompressor = None 
+ 
+    def headers_received(self, start_line, headers): 
+        if headers.get("Content-Encoding") == "gzip": 
+            self._decompressor = GzipDecompressor() 
+            # Downstream delegates will only see uncompressed data, 
+            # so rename the content-encoding header. 
+            # (but note that curl_httpclient doesn't do this). 
+            headers.add("X-Consumed-Content-Encoding", 
+                        headers["Content-Encoding"]) 
+            del headers["Content-Encoding"] 
+        return self._delegate.headers_received(start_line, headers) 
+ 
+    @gen.coroutine 
+    def data_received(self, chunk): 
+        if self._decompressor: 
+            compressed_data = chunk 
+            while compressed_data: 
+                decompressed = self._decompressor.decompress( 
+                    compressed_data, self._chunk_size) 
+                if decompressed: 
+                    ret = self._delegate.data_received(decompressed) 
+                    if ret is not None: 
+                        yield ret 
+                compressed_data = self._decompressor.unconsumed_tail 
+        else: 
+            ret = self._delegate.data_received(chunk) 
+            if ret is not None: 
+                yield ret 
+ 
+    def finish(self): 
+        if self._decompressor is not None: 
+            tail = self._decompressor.flush() 
+            if tail: 
+                # I believe the tail will always be empty (i.e. 
+                # decompress will return all it can).  The purpose 
+                # of the flush call is to detect errors such 
+                # as truncated input.  But in case it ever returns 
+                # anything, treat it as an extra chunk 
+                self._delegate.data_received(tail) 
+        return self._delegate.finish() 
+ 
+    def on_connection_close(self): 
+        return self._delegate.on_connection_close() 
+ 
+ 
+class HTTP1ServerConnection(object): 
+    """An HTTP/1.x server.""" 
+    def __init__(self, stream, params=None, context=None): 
+        """ 
+        :arg stream: an `.IOStream` 
+        :arg params: a `.HTTP1ConnectionParameters` or None 
+        :arg context: an opaque application-defined object that is accessible 
+            as ``connection.context`` 
+        """ 
+        self.stream = stream 
+        if params is None: 
+            params = HTTP1ConnectionParameters() 
+        self.params = params 
+        self.context = context 
+        self._serving_future = None 
+ 
+    @gen.coroutine 
+    def close(self): 
+        """Closes the connection. 
+ 
+        Returns a `.Future` that resolves after the serving loop has exited. 
+        """ 
+        self.stream.close() 
+        # Block until the serving loop is done, but ignore any exceptions 
+        # (start_serving is already responsible for logging them). 
+        try: 
+            yield self._serving_future 
+        except Exception: 
+            pass 
+ 
+    def start_serving(self, delegate): 
+        """Starts serving requests on this connection. 
+ 
+        :arg delegate: a `.HTTPServerConnectionDelegate` 
+        """ 
+        assert isinstance(delegate, httputil.HTTPServerConnectionDelegate) 
+        self._serving_future = self._server_request_loop(delegate) 
+        # Register the future on the IOLoop so its errors get logged. 
+        self.stream.io_loop.add_future(self._serving_future, 
+                                       lambda f: f.result()) 
+ 
+    @gen.coroutine 
+    def _server_request_loop(self, delegate): 
+        try: 
+            while True: 
+                conn = HTTP1Connection(self.stream, False, 
+                                       self.params, self.context) 
+                request_delegate = delegate.start_request(self, conn) 
+                try: 
+                    ret = yield conn.read_response(request_delegate) 
+                except (iostream.StreamClosedError, 
+                        iostream.UnsatisfiableReadError): 
+                    return 
+                except _QuietException: 
+                    # This exception was already logged. 
+                    conn.close() 
+                    return 
+                except Exception: 
+                    gen_log.error("Uncaught exception", exc_info=True) 
+                    conn.close() 
+                    return 
+                if not ret: 
+                    return 
+                yield gen.moment 
+        finally: 
+            delegate.on_close(self) 
diff --git a/contrib/python/tornado/tornado-4/tornado/httpclient.py b/contrib/python/tornado/tornado-4/tornado/httpclient.py
index 8436ece469..1e7e5f2a2f 100644
--- a/contrib/python/tornado/tornado-4/tornado/httpclient.py
+++ b/contrib/python/tornado/tornado-4/tornado/httpclient.py
@@ -1,678 +1,678 @@
-"""Blocking and non-blocking HTTP client interfaces.
-
-This module defines a common interface shared by two implementations,
-``simple_httpclient`` and ``curl_httpclient``.  Applications may either
-instantiate their chosen implementation class directly or use the
-`AsyncHTTPClient` class from this module, which selects an implementation
-that can be overridden with the `AsyncHTTPClient.configure` method.
-
-The default implementation is ``simple_httpclient``, and this is expected
-to be suitable for most users' needs.  However, some applications may wish
-to switch to ``curl_httpclient`` for reasons such as the following:
-
-* ``curl_httpclient`` has some features not found in ``simple_httpclient``,
-  including support for HTTP proxies and the ability to use a specified
-  network interface.
-
-* ``curl_httpclient`` is more likely to be compatible with sites that are
-  not-quite-compliant with the HTTP spec, or sites that use little-exercised
-  features of HTTP.
-
-* ``curl_httpclient`` is faster.
-
-* ``curl_httpclient`` was the default prior to Tornado 2.0.
-
-Note that if you are using ``curl_httpclient``, it is highly
-recommended that you use a recent version of ``libcurl`` and
-``pycurl``.  Currently the minimum supported version of libcurl is
-7.22.0, and the minimum version of pycurl is 7.18.2.  It is highly
-recommended that your ``libcurl`` installation is built with
-asynchronous DNS resolver (threaded or c-ares), otherwise you may
-encounter various problems with request timeouts (for more
-information, see
-http://curl.haxx.se/libcurl/c/curl_easy_setopt.html#CURLOPTCONNECTTIMEOUTMS
-and comments in curl_httpclient.py).
-
-To select ``curl_httpclient``, call `AsyncHTTPClient.configure` at startup::
-
-    AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import functools
-import time
-import weakref
-
-from tornado.concurrent import TracebackFuture
-from tornado.escape import utf8, native_str
-from tornado import httputil, stack_context
-from tornado.ioloop import IOLoop
-from tornado.util import Configurable
-
-
-class HTTPClient(object):
-    """A blocking HTTP client.
-
-    This interface is provided for convenience and testing; most applications
-    that are running an IOLoop will want to use `AsyncHTTPClient` instead.
-    Typical usage looks like this::
-
-        http_client = httpclient.HTTPClient()
-        try:
-            response = http_client.fetch("http://www.google.com/")
-            print(response.body)
-        except httpclient.HTTPError as e:
-            # HTTPError is raised for non-200 responses; the response
-            # can be found in e.response.
-            print("Error: " + str(e))
-        except Exception as e:
-            # Other errors are possible, such as IOError.
-            print("Error: " + str(e))
-        http_client.close()
-    """
-    def __init__(self, async_client_class=None, **kwargs):
-        self._io_loop = IOLoop(make_current=False)
-        if async_client_class is None:
-            async_client_class = AsyncHTTPClient
-        self._async_client = async_client_class(self._io_loop, **kwargs)
-        self._closed = False
-
-    def __del__(self):
-        self.close()
-
-    def close(self):
-        """Closes the HTTPClient, freeing any resources used."""
-        if not self._closed:
-            self._async_client.close()
-            self._io_loop.close()
-            self._closed = True
-
-    def fetch(self, request, **kwargs):
-        """Executes a request, returning an `HTTPResponse`.
-
-        The request may be either a string URL or an `HTTPRequest` object.
-        If it is a string, we construct an `HTTPRequest` using any additional
-        kwargs: ``HTTPRequest(request, **kwargs)``
-
-        If an error occurs during the fetch, we raise an `HTTPError` unless
-        the ``raise_error`` keyword argument is set to False.
-        """
-        response = self._io_loop.run_sync(functools.partial(
-            self._async_client.fetch, request, **kwargs))
-        return response
-
-
-class AsyncHTTPClient(Configurable):
-    """An non-blocking HTTP client.
-
-    Example usage::
-
-        def handle_response(response):
-            if response.error:
-                print("Error: %s" % response.error)
-            else:
-                print(response.body)
-
-        http_client = AsyncHTTPClient()
-        http_client.fetch("http://www.google.com/", handle_response)
-
-    The constructor for this class is magic in several respects: It
-    actually creates an instance of an implementation-specific
-    subclass, and instances are reused as a kind of pseudo-singleton
-    (one per `.IOLoop`).  The keyword argument ``force_instance=True``
-    can be used to suppress this singleton behavior.  Unless
-    ``force_instance=True`` is used, no arguments other than
-    ``io_loop`` should be passed to the `AsyncHTTPClient` constructor.
-    The implementation subclass as well as arguments to its
-    constructor can be set with the static method `configure()`
-
-    All `AsyncHTTPClient` implementations support a ``defaults``
-    keyword argument, which can be used to set default values for
-    `HTTPRequest` attributes.  For example::
-
-        AsyncHTTPClient.configure(
-            None, defaults=dict(user_agent="MyUserAgent"))
-        # or with force_instance:
-        client = AsyncHTTPClient(force_instance=True,
-            defaults=dict(user_agent="MyUserAgent"))
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-    """
-    @classmethod
-    def configurable_base(cls):
-        return AsyncHTTPClient
-
-    @classmethod
-    def configurable_default(cls):
-        from tornado.simple_httpclient import SimpleAsyncHTTPClient
-        return SimpleAsyncHTTPClient
-
-    @classmethod
-    def _async_clients(cls):
-        attr_name = '_async_client_dict_' + cls.__name__
-        if not hasattr(cls, attr_name):
-            setattr(cls, attr_name, weakref.WeakKeyDictionary())
-        return getattr(cls, attr_name)
-
-    def __new__(cls, io_loop=None, force_instance=False, **kwargs):
-        io_loop = io_loop or IOLoop.current()
-        if force_instance:
-            instance_cache = None
-        else:
-            instance_cache = cls._async_clients()
-        if instance_cache is not None and io_loop in instance_cache:
-            return instance_cache[io_loop]
-        instance = super(AsyncHTTPClient, cls).__new__(cls, io_loop=io_loop,
-                                                       **kwargs)
-        # Make sure the instance knows which cache to remove itself from.
-        # It can't simply call _async_clients() because we may be in
-        # __new__(AsyncHTTPClient) but instance.__class__ may be
-        # SimpleAsyncHTTPClient.
-        instance._instance_cache = instance_cache
-        if instance_cache is not None:
-            instance_cache[instance.io_loop] = instance
-        return instance
-
-    def initialize(self, io_loop, defaults=None):
-        self.io_loop = io_loop
-        self.defaults = dict(HTTPRequest._DEFAULTS)
-        if defaults is not None:
-            self.defaults.update(defaults)
-        self._closed = False
-
-    def close(self):
-        """Destroys this HTTP client, freeing any file descriptors used.
-
-        This method is **not needed in normal use** due to the way
-        that `AsyncHTTPClient` objects are transparently reused.
-        ``close()`` is generally only necessary when either the
-        `.IOLoop` is also being closed, or the ``force_instance=True``
-        argument was used when creating the `AsyncHTTPClient`.
-
-        No other methods may be called on the `AsyncHTTPClient` after
-        ``close()``.
-
-        """
-        if self._closed:
-            return
-        self._closed = True
-        if self._instance_cache is not None:
-            if self._instance_cache.get(self.io_loop) is not self:
-                raise RuntimeError("inconsistent AsyncHTTPClient cache")
-            del self._instance_cache[self.io_loop]
-
-    def fetch(self, request, callback=None, raise_error=True, **kwargs):
-        """Executes a request, asynchronously returning an `HTTPResponse`.
-
-        The request may be either a string URL or an `HTTPRequest` object.
-        If it is a string, we construct an `HTTPRequest` using any additional
-        kwargs: ``HTTPRequest(request, **kwargs)``
-
-        This method returns a `.Future` whose result is an
-        `HTTPResponse`. By default, the ``Future`` will raise an
-        `HTTPError` if the request returned a non-200 response code
-        (other errors may also be raised if the server could not be
-        contacted). Instead, if ``raise_error`` is set to False, the
-        response will always be returned regardless of the response
-        code.
-
-        If a ``callback`` is given, it will be invoked with the `HTTPResponse`.
-        In the callback interface, `HTTPError` is not automatically raised.
-        Instead, you must check the response's ``error`` attribute or
-        call its `~HTTPResponse.rethrow` method.
-        """
-        if self._closed:
-            raise RuntimeError("fetch() called on closed AsyncHTTPClient")
-        if not isinstance(request, HTTPRequest):
-            request = HTTPRequest(url=request, **kwargs)
-        else:
-            if kwargs:
-                raise ValueError("kwargs can't be used if request is an HTTPRequest object")
-        # We may modify this (to add Host, Accept-Encoding, etc),
-        # so make sure we don't modify the caller's object.  This is also
-        # where normal dicts get converted to HTTPHeaders objects.
-        request.headers = httputil.HTTPHeaders(request.headers)
-        request = _RequestProxy(request, self.defaults)
-        future = TracebackFuture()
-        if callback is not None:
-            callback = stack_context.wrap(callback)
-
-            def handle_future(future):
-                exc = future.exception()
-                if isinstance(exc, HTTPError) and exc.response is not None:
-                    response = exc.response
-                elif exc is not None:
-                    response = HTTPResponse(
-                        request, 599, error=exc,
-                        request_time=time.time() - request.start_time)
-                else:
-                    response = future.result()
-                self.io_loop.add_callback(callback, response)
-            future.add_done_callback(handle_future)
-
-        def handle_response(response):
-            if raise_error and response.error:
-                future.set_exception(response.error)
-            else:
-                future.set_result(response)
-        self.fetch_impl(request, handle_response)
-        return future
-
-    def fetch_impl(self, request, callback):
-        raise NotImplementedError()
-
-    @classmethod
-    def configure(cls, impl, **kwargs):
-        """Configures the `AsyncHTTPClient` subclass to use.
-
-        ``AsyncHTTPClient()`` actually creates an instance of a subclass.
-        This method may be called with either a class object or the
-        fully-qualified name of such a class (or ``None`` to use the default,
-        ``SimpleAsyncHTTPClient``)
-
-        If additional keyword arguments are given, they will be passed
-        to the constructor of each subclass instance created.  The
-        keyword argument ``max_clients`` determines the maximum number
-        of simultaneous `~AsyncHTTPClient.fetch()` operations that can
-        execute in parallel on each `.IOLoop`.  Additional arguments
-        may be supported depending on the implementation class in use.
-
-        Example::
-
-           AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")
-        """
-        super(AsyncHTTPClient, cls).configure(impl, **kwargs)
-
-
-class HTTPRequest(object):
-    """HTTP client request object."""
-
-    # Default values for HTTPRequest parameters.
-    # Merged with the values on the request object by AsyncHTTPClient
-    # implementations.
-    _DEFAULTS = dict(
-        connect_timeout=20.0,
-        request_timeout=20.0,
-        follow_redirects=True,
-        max_redirects=5,
-        decompress_response=True,
-        proxy_password='',
-        allow_nonstandard_methods=False,
-        validate_cert=True)
-
-    def __init__(self, url, method="GET", headers=None, body=None,
-                 auth_username=None, auth_password=None, auth_mode=None,
-                 connect_timeout=None, request_timeout=None,
-                 if_modified_since=None, follow_redirects=None,
-                 max_redirects=None, user_agent=None, use_gzip=None,
-                 network_interface=None, streaming_callback=None,
-                 header_callback=None, prepare_curl_callback=None,
-                 proxy_host=None, proxy_port=None, proxy_username=None,
-                 proxy_password=None, proxy_auth_mode=None,
-                 allow_nonstandard_methods=None, validate_cert=None,
-                 ca_certs=None, allow_ipv6=None, client_key=None,
-                 client_cert=None, body_producer=None,
-                 expect_100_continue=False, decompress_response=None,
-                 ssl_options=None):
-        r"""All parameters except ``url`` are optional.
-
-        :arg string url: URL to fetch
-        :arg string method: HTTP method, e.g. "GET" or "POST"
-        :arg headers: Additional HTTP headers to pass on the request
-        :type headers: `~tornado.httputil.HTTPHeaders` or `dict`
-        :arg body: HTTP request body as a string (byte or unicode; if unicode
-           the utf-8 encoding will be used)
-        :arg body_producer: Callable used for lazy/asynchronous request bodies.
-           It is called with one argument, a ``write`` function, and should
-           return a `.Future`.  It should call the write function with new
-           data as it becomes available.  The write function returns a
-           `.Future` which can be used for flow control.
-           Only one of ``body`` and ``body_producer`` may
-           be specified.  ``body_producer`` is not supported on
-           ``curl_httpclient``.  When using ``body_producer`` it is recommended
-           to pass a ``Content-Length`` in the headers as otherwise chunked
-           encoding will be used, and many servers do not support chunked
-           encoding on requests.  New in Tornado 4.0
-        :arg string auth_username: Username for HTTP authentication
-        :arg string auth_password: Password for HTTP authentication
-        :arg string auth_mode: Authentication mode; default is "basic".
-           Allowed values are implementation-defined; ``curl_httpclient``
-           supports "basic" and "digest"; ``simple_httpclient`` only supports
-           "basic"
-        :arg float connect_timeout: Timeout for initial connection in seconds,
-           default 20 seconds
-        :arg float request_timeout: Timeout for entire request in seconds,
-           default 20 seconds
-        :arg if_modified_since: Timestamp for ``If-Modified-Since`` header
-        :type if_modified_since: `datetime` or `float`
-        :arg bool follow_redirects: Should redirects be followed automatically
-           or return the 3xx response? Default True.
-        :arg int max_redirects: Limit for ``follow_redirects``, default 5.
-        :arg string user_agent: String to send as ``User-Agent`` header
-        :arg bool decompress_response: Request a compressed response from
-           the server and decompress it after downloading.  Default is True.
-           New in Tornado 4.0.
-        :arg bool use_gzip: Deprecated alias for ``decompress_response``
-           since Tornado 4.0.
-        :arg string network_interface: Network interface to use for request.
-           ``curl_httpclient`` only; see note below.
-        :arg callable streaming_callback: If set, ``streaming_callback`` will
-           be run with each chunk of data as it is received, and
-           ``HTTPResponse.body`` and ``HTTPResponse.buffer`` will be empty in
-           the final response.
-        :arg callable header_callback: If set, ``header_callback`` will
-           be run with each header line as it is received (including the
-           first line, e.g. ``HTTP/1.0 200 OK\r\n``, and a final line
-           containing only ``\r\n``.  All lines include the trailing newline
-           characters).  ``HTTPResponse.headers`` will be empty in the final
-           response.  This is most useful in conjunction with
-           ``streaming_callback``, because it's the only way to get access to
-           header data while the request is in progress.
-        :arg callable prepare_curl_callback: If set, will be called with
-           a ``pycurl.Curl`` object to allow the application to make additional
-           ``setopt`` calls.
-        :arg string proxy_host: HTTP proxy hostname.  To use proxies,
-           ``proxy_host`` and ``proxy_port`` must be set; ``proxy_username``,
-           ``proxy_pass`` and ``proxy_auth_mode`` are optional.  Proxies are
-           currently only supported with ``curl_httpclient``.
-        :arg int proxy_port: HTTP proxy port
-        :arg string proxy_username: HTTP proxy username
-        :arg string proxy_password: HTTP proxy password
-        :arg string proxy_auth_mode: HTTP proxy Authentication mode;
-           default is "basic". supports "basic" and "digest"
-        :arg bool allow_nonstandard_methods: Allow unknown values for ``method``
-           argument? Default is False.
-        :arg bool validate_cert: For HTTPS requests, validate the server's
-           certificate? Default is True.
-        :arg string ca_certs: filename of CA certificates in PEM format,
-           or None to use defaults.  See note below when used with
-           ``curl_httpclient``.
-        :arg string client_key: Filename for client SSL key, if any.  See
-           note below when used with ``curl_httpclient``.
-        :arg string client_cert: Filename for client SSL certificate, if any.
-           See note below when used with ``curl_httpclient``.
-        :arg ssl.SSLContext ssl_options: `ssl.SSLContext` object for use in
-           ``simple_httpclient`` (unsupported by ``curl_httpclient``).
-           Overrides ``validate_cert``, ``ca_certs``, ``client_key``,
-           and ``client_cert``.
-        :arg bool allow_ipv6: Use IPv6 when available?  Default is true.
-        :arg bool expect_100_continue: If true, send the
-           ``Expect: 100-continue`` header and wait for a continue response
-           before sending the request body.  Only supported with
-           simple_httpclient.
-
-        .. note::
-
-            When using ``curl_httpclient`` certain options may be
-            inherited by subsequent fetches because ``pycurl`` does
-            not allow them to be cleanly reset.  This applies to the
-            ``ca_certs``, ``client_key``, ``client_cert``, and
-            ``network_interface`` arguments.  If you use these
-            options, you should pass them on every request (you don't
-            have to always use the same values, but it's not possible
-            to mix requests that specify these options with ones that
-            use the defaults).
-
-        .. versionadded:: 3.1
-           The ``auth_mode`` argument.
-
-        .. versionadded:: 4.0
-           The ``body_producer`` and ``expect_100_continue`` arguments.
-
-        .. versionadded:: 4.2
-           The ``ssl_options`` argument.
-
-        .. versionadded:: 4.5
-           The ``proxy_auth_mode`` argument.
-        """
-        # Note that some of these attributes go through property setters
-        # defined below.
-        self.headers = headers
-        if if_modified_since:
-            self.headers["If-Modified-Since"] = httputil.format_timestamp(
-                if_modified_since)
-        self.proxy_host = proxy_host
-        self.proxy_port = proxy_port
-        self.proxy_username = proxy_username
-        self.proxy_password = proxy_password
-        self.proxy_auth_mode = proxy_auth_mode
-        self.url = url
-        self.method = method
-        self.body = body
-        self.body_producer = body_producer
-        self.auth_username = auth_username
-        self.auth_password = auth_password
-        self.auth_mode = auth_mode
-        self.connect_timeout = connect_timeout
-        self.request_timeout = request_timeout
-        self.follow_redirects = follow_redirects
-        self.max_redirects = max_redirects
-        self.user_agent = user_agent
-        if decompress_response is not None:
-            self.decompress_response = decompress_response
-        else:
-            self.decompress_response = use_gzip
-        self.network_interface = network_interface
-        self.streaming_callback = streaming_callback
-        self.header_callback = header_callback
-        self.prepare_curl_callback = prepare_curl_callback
-        self.allow_nonstandard_methods = allow_nonstandard_methods
-        self.validate_cert = validate_cert
-        self.ca_certs = ca_certs
-        self.allow_ipv6 = allow_ipv6
-        self.client_key = client_key
-        self.client_cert = client_cert
-        self.ssl_options = ssl_options
-        self.expect_100_continue = expect_100_continue
-        self.start_time = time.time()
-
-    @property
-    def headers(self):
-        return self._headers
-
-    @headers.setter
-    def headers(self, value):
-        if value is None:
-            self._headers = httputil.HTTPHeaders()
-        else:
-            self._headers = value
-
-    @property
-    def body(self):
-        return self._body
-
-    @body.setter
-    def body(self, value):
-        self._body = utf8(value)
-
-    @property
-    def body_producer(self):
-        return self._body_producer
-
-    @body_producer.setter
-    def body_producer(self, value):
-        self._body_producer = stack_context.wrap(value)
-
-    @property
-    def streaming_callback(self):
-        return self._streaming_callback
-
-    @streaming_callback.setter
-    def streaming_callback(self, value):
-        self._streaming_callback = stack_context.wrap(value)
-
-    @property
-    def header_callback(self):
-        return self._header_callback
-
-    @header_callback.setter
-    def header_callback(self, value):
-        self._header_callback = stack_context.wrap(value)
-
-    @property
-    def prepare_curl_callback(self):
-        return self._prepare_curl_callback
-
-    @prepare_curl_callback.setter
-    def prepare_curl_callback(self, value):
-        self._prepare_curl_callback = stack_context.wrap(value)
-
-
-class HTTPResponse(object):
-    """HTTP Response object.
-
-    Attributes:
-
-    * request: HTTPRequest object
-
-    * code: numeric HTTP status code, e.g. 200 or 404
-
-    * reason: human-readable reason phrase describing the status code
-
-    * headers: `tornado.httputil.HTTPHeaders` object
-
-    * effective_url: final location of the resource after following any
-      redirects
-
-    * buffer: ``cStringIO`` object for response body
-
-    * body: response body as bytes (created on demand from ``self.buffer``)
-
-    * error: Exception object, if any
-
-    * request_time: seconds from request start to finish
-
-    * time_info: dictionary of diagnostic timing information from the request.
-      Available data are subject to change, but currently uses timings
-      available from http://curl.haxx.se/libcurl/c/curl_easy_getinfo.html,
-      plus ``queue``, which is the delay (if any) introduced by waiting for
-      a slot under `AsyncHTTPClient`'s ``max_clients`` setting.
-    """
-    def __init__(self, request, code, headers=None, buffer=None,
-                 effective_url=None, error=None, request_time=None,
-                 time_info=None, reason=None):
-        if isinstance(request, _RequestProxy):
-            self.request = request.request
-        else:
-            self.request = request
-        self.code = code
-        self.reason = reason or httputil.responses.get(code, "Unknown")
-        if headers is not None:
-            self.headers = headers
-        else:
-            self.headers = httputil.HTTPHeaders()
-        self.buffer = buffer
-        self._body = None
-        if effective_url is None:
-            self.effective_url = request.url
-        else:
-            self.effective_url = effective_url
-        if error is None:
-            if self.code < 200 or self.code >= 300:
-                self.error = HTTPError(self.code, message=self.reason,
-                                       response=self)
-            else:
-                self.error = None
-        else:
-            self.error = error
-        self.request_time = request_time
-        self.time_info = time_info or {}
-
-    @property
-    def body(self):
-        if self.buffer is None:
-            return None
-        elif self._body is None:
-            self._body = self.buffer.getvalue()
-
-        return self._body
-
-    def rethrow(self):
-        """If there was an error on the request, raise an `HTTPError`."""
-        if self.error:
-            raise self.error
-
-    def __repr__(self):
-        args = ",".join("%s=%r" % i for i in sorted(self.__dict__.items()))
-        return "%s(%s)" % (self.__class__.__name__, args)
-
-
-class HTTPError(Exception):
-    """Exception thrown for an unsuccessful HTTP request.
-
-    Attributes:
-
-    * ``code`` - HTTP error integer error code, e.g. 404.  Error code 599 is
-      used when no HTTP response was received, e.g. for a timeout.
-
-    * ``response`` - `HTTPResponse` object, if any.
-
-    Note that if ``follow_redirects`` is False, redirects become HTTPErrors,
-    and you can look at ``error.response.headers['Location']`` to see the
-    destination of the redirect.
-    """
-    def __init__(self, code, message=None, response=None):
-        self.code = code
-        self.message = message or httputil.responses.get(code, "Unknown")
-        self.response = response
-        super(HTTPError, self).__init__(code, message, response)
-
-    def __str__(self):
-        return "HTTP %d: %s" % (self.code, self.message)
-
-    # There is a cyclic reference between self and self.response,
-    # which breaks the default __repr__ implementation.
-    # (especially on pypy, which doesn't have the same recursion
-    # detection as cpython).
-    __repr__ = __str__
-
-
-class _RequestProxy(object):
-    """Combines an object with a dictionary of defaults.
-
-    Used internally by AsyncHTTPClient implementations.
-    """
-    def __init__(self, request, defaults):
-        self.request = request
-        self.defaults = defaults
-
-    def __getattr__(self, name):
-        request_attr = getattr(self.request, name)
-        if request_attr is not None:
-            return request_attr
-        elif self.defaults is not None:
-            return self.defaults.get(name, None)
-        else:
-            return None
-
-
-def main():
-    from tornado.options import define, options, parse_command_line
-    define("print_headers", type=bool, default=False)
-    define("print_body", type=bool, default=True)
-    define("follow_redirects", type=bool, default=True)
-    define("validate_cert", type=bool, default=True)
-    args = parse_command_line()
-    client = HTTPClient()
-    for arg in args:
-        try:
-            response = client.fetch(arg,
-                                    follow_redirects=options.follow_redirects,
-                                    validate_cert=options.validate_cert,
-                                    )
-        except HTTPError as e:
-            if e.response is not None:
-                response = e.response
-            else:
-                raise
-        if options.print_headers:
-            print(response.headers)
-        if options.print_body:
-            print(native_str(response.body))
-    client.close()
-
-
-if __name__ == "__main__":
-    main()
+"""Blocking and non-blocking HTTP client interfaces. 
+ 
+This module defines a common interface shared by two implementations, 
+``simple_httpclient`` and ``curl_httpclient``.  Applications may either 
+instantiate their chosen implementation class directly or use the 
+`AsyncHTTPClient` class from this module, which selects an implementation 
+that can be overridden with the `AsyncHTTPClient.configure` method. 
+ 
+The default implementation is ``simple_httpclient``, and this is expected 
+to be suitable for most users' needs.  However, some applications may wish 
+to switch to ``curl_httpclient`` for reasons such as the following: 
+ 
+* ``curl_httpclient`` has some features not found in ``simple_httpclient``, 
+  including support for HTTP proxies and the ability to use a specified 
+  network interface. 
+ 
+* ``curl_httpclient`` is more likely to be compatible with sites that are 
+  not-quite-compliant with the HTTP spec, or sites that use little-exercised 
+  features of HTTP. 
+ 
+* ``curl_httpclient`` is faster. 
+ 
+* ``curl_httpclient`` was the default prior to Tornado 2.0. 
+ 
+Note that if you are using ``curl_httpclient``, it is highly 
+recommended that you use a recent version of ``libcurl`` and 
+``pycurl``.  Currently the minimum supported version of libcurl is 
+7.22.0, and the minimum version of pycurl is 7.18.2.  It is highly 
+recommended that your ``libcurl`` installation is built with 
+asynchronous DNS resolver (threaded or c-ares), otherwise you may 
+encounter various problems with request timeouts (for more 
+information, see 
+http://curl.haxx.se/libcurl/c/curl_easy_setopt.html#CURLOPTCONNECTTIMEOUTMS 
+and comments in curl_httpclient.py). 
+ 
+To select ``curl_httpclient``, call `AsyncHTTPClient.configure` at startup:: 
+ 
+    AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient") 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import functools 
+import time 
+import weakref 
+ 
+from tornado.concurrent import TracebackFuture 
+from tornado.escape import utf8, native_str 
+from tornado import httputil, stack_context 
+from tornado.ioloop import IOLoop 
+from tornado.util import Configurable 
+ 
+ 
+class HTTPClient(object): 
+    """A blocking HTTP client. 
+ 
+    This interface is provided for convenience and testing; most applications 
+    that are running an IOLoop will want to use `AsyncHTTPClient` instead. 
+    Typical usage looks like this:: 
+ 
+        http_client = httpclient.HTTPClient() 
+        try: 
+            response = http_client.fetch("http://www.google.com/") 
+            print(response.body) 
+        except httpclient.HTTPError as e: 
+            # HTTPError is raised for non-200 responses; the response 
+            # can be found in e.response. 
+            print("Error: " + str(e)) 
+        except Exception as e: 
+            # Other errors are possible, such as IOError. 
+            print("Error: " + str(e)) 
+        http_client.close() 
+    """ 
+    def __init__(self, async_client_class=None, **kwargs): 
+        self._io_loop = IOLoop(make_current=False) 
+        if async_client_class is None: 
+            async_client_class = AsyncHTTPClient 
+        self._async_client = async_client_class(self._io_loop, **kwargs) 
+        self._closed = False 
+ 
+    def __del__(self): 
+        self.close() 
+ 
+    def close(self): 
+        """Closes the HTTPClient, freeing any resources used.""" 
+        if not self._closed: 
+            self._async_client.close() 
+            self._io_loop.close() 
+            self._closed = True 
+ 
+    def fetch(self, request, **kwargs): 
+        """Executes a request, returning an `HTTPResponse`. 
+ 
+        The request may be either a string URL or an `HTTPRequest` object. 
+        If it is a string, we construct an `HTTPRequest` using any additional 
+        kwargs: ``HTTPRequest(request, **kwargs)`` 
+ 
+        If an error occurs during the fetch, we raise an `HTTPError` unless 
+        the ``raise_error`` keyword argument is set to False. 
+        """ 
+        response = self._io_loop.run_sync(functools.partial( 
+            self._async_client.fetch, request, **kwargs)) 
+        return response 
+ 
+ 
+class AsyncHTTPClient(Configurable): 
+    """An non-blocking HTTP client. 
+ 
+    Example usage:: 
+ 
+        def handle_response(response): 
+            if response.error: 
+                print("Error: %s" % response.error) 
+            else: 
+                print(response.body) 
+ 
+        http_client = AsyncHTTPClient() 
+        http_client.fetch("http://www.google.com/", handle_response) 
+ 
+    The constructor for this class is magic in several respects: It 
+    actually creates an instance of an implementation-specific 
+    subclass, and instances are reused as a kind of pseudo-singleton 
+    (one per `.IOLoop`).  The keyword argument ``force_instance=True`` 
+    can be used to suppress this singleton behavior.  Unless 
+    ``force_instance=True`` is used, no arguments other than 
+    ``io_loop`` should be passed to the `AsyncHTTPClient` constructor. 
+    The implementation subclass as well as arguments to its 
+    constructor can be set with the static method `configure()` 
+ 
+    All `AsyncHTTPClient` implementations support a ``defaults`` 
+    keyword argument, which can be used to set default values for 
+    `HTTPRequest` attributes.  For example:: 
+ 
+        AsyncHTTPClient.configure( 
+            None, defaults=dict(user_agent="MyUserAgent")) 
+        # or with force_instance: 
+        client = AsyncHTTPClient(force_instance=True, 
+            defaults=dict(user_agent="MyUserAgent")) 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+    """ 
+    @classmethod 
+    def configurable_base(cls): 
+        return AsyncHTTPClient 
+ 
+    @classmethod 
+    def configurable_default(cls): 
+        from tornado.simple_httpclient import SimpleAsyncHTTPClient 
+        return SimpleAsyncHTTPClient 
+ 
+    @classmethod 
+    def _async_clients(cls): 
+        attr_name = '_async_client_dict_' + cls.__name__ 
+        if not hasattr(cls, attr_name): 
+            setattr(cls, attr_name, weakref.WeakKeyDictionary()) 
+        return getattr(cls, attr_name) 
+ 
+    def __new__(cls, io_loop=None, force_instance=False, **kwargs): 
+        io_loop = io_loop or IOLoop.current() 
+        if force_instance: 
+            instance_cache = None 
+        else: 
+            instance_cache = cls._async_clients() 
+        if instance_cache is not None and io_loop in instance_cache: 
+            return instance_cache[io_loop] 
+        instance = super(AsyncHTTPClient, cls).__new__(cls, io_loop=io_loop, 
+                                                       **kwargs) 
+        # Make sure the instance knows which cache to remove itself from. 
+        # It can't simply call _async_clients() because we may be in 
+        # __new__(AsyncHTTPClient) but instance.__class__ may be 
+        # SimpleAsyncHTTPClient. 
+        instance._instance_cache = instance_cache 
+        if instance_cache is not None: 
+            instance_cache[instance.io_loop] = instance 
+        return instance 
+ 
+    def initialize(self, io_loop, defaults=None): 
+        self.io_loop = io_loop 
+        self.defaults = dict(HTTPRequest._DEFAULTS) 
+        if defaults is not None: 
+            self.defaults.update(defaults) 
+        self._closed = False 
+ 
+    def close(self): 
+        """Destroys this HTTP client, freeing any file descriptors used. 
+ 
+        This method is **not needed in normal use** due to the way 
+        that `AsyncHTTPClient` objects are transparently reused. 
+        ``close()`` is generally only necessary when either the 
+        `.IOLoop` is also being closed, or the ``force_instance=True`` 
+        argument was used when creating the `AsyncHTTPClient`. 
+ 
+        No other methods may be called on the `AsyncHTTPClient` after 
+        ``close()``. 
+ 
+        """ 
+        if self._closed: 
+            return 
+        self._closed = True 
+        if self._instance_cache is not None: 
+            if self._instance_cache.get(self.io_loop) is not self: 
+                raise RuntimeError("inconsistent AsyncHTTPClient cache") 
+            del self._instance_cache[self.io_loop] 
+ 
+    def fetch(self, request, callback=None, raise_error=True, **kwargs): 
+        """Executes a request, asynchronously returning an `HTTPResponse`. 
+ 
+        The request may be either a string URL or an `HTTPRequest` object. 
+        If it is a string, we construct an `HTTPRequest` using any additional 
+        kwargs: ``HTTPRequest(request, **kwargs)`` 
+ 
+        This method returns a `.Future` whose result is an 
+        `HTTPResponse`. By default, the ``Future`` will raise an 
+        `HTTPError` if the request returned a non-200 response code 
+        (other errors may also be raised if the server could not be 
+        contacted). Instead, if ``raise_error`` is set to False, the 
+        response will always be returned regardless of the response 
+        code. 
+ 
+        If a ``callback`` is given, it will be invoked with the `HTTPResponse`. 
+        In the callback interface, `HTTPError` is not automatically raised. 
+        Instead, you must check the response's ``error`` attribute or 
+        call its `~HTTPResponse.rethrow` method. 
+        """ 
+        if self._closed: 
+            raise RuntimeError("fetch() called on closed AsyncHTTPClient") 
+        if not isinstance(request, HTTPRequest): 
+            request = HTTPRequest(url=request, **kwargs) 
+        else: 
+            if kwargs: 
+                raise ValueError("kwargs can't be used if request is an HTTPRequest object") 
+        # We may modify this (to add Host, Accept-Encoding, etc), 
+        # so make sure we don't modify the caller's object.  This is also 
+        # where normal dicts get converted to HTTPHeaders objects. 
+        request.headers = httputil.HTTPHeaders(request.headers) 
+        request = _RequestProxy(request, self.defaults) 
+        future = TracebackFuture() 
+        if callback is not None: 
+            callback = stack_context.wrap(callback) 
+ 
+            def handle_future(future): 
+                exc = future.exception() 
+                if isinstance(exc, HTTPError) and exc.response is not None: 
+                    response = exc.response 
+                elif exc is not None: 
+                    response = HTTPResponse( 
+                        request, 599, error=exc, 
+                        request_time=time.time() - request.start_time) 
+                else: 
+                    response = future.result() 
+                self.io_loop.add_callback(callback, response) 
+            future.add_done_callback(handle_future) 
+ 
+        def handle_response(response): 
+            if raise_error and response.error: 
+                future.set_exception(response.error) 
+            else: 
+                future.set_result(response) 
+        self.fetch_impl(request, handle_response) 
+        return future 
+ 
+    def fetch_impl(self, request, callback): 
+        raise NotImplementedError() 
+ 
+    @classmethod 
+    def configure(cls, impl, **kwargs): 
+        """Configures the `AsyncHTTPClient` subclass to use. 
+ 
+        ``AsyncHTTPClient()`` actually creates an instance of a subclass. 
+        This method may be called with either a class object or the 
+        fully-qualified name of such a class (or ``None`` to use the default, 
+        ``SimpleAsyncHTTPClient``) 
+ 
+        If additional keyword arguments are given, they will be passed 
+        to the constructor of each subclass instance created.  The 
+        keyword argument ``max_clients`` determines the maximum number 
+        of simultaneous `~AsyncHTTPClient.fetch()` operations that can 
+        execute in parallel on each `.IOLoop`.  Additional arguments 
+        may be supported depending on the implementation class in use. 
+ 
+        Example:: 
+ 
+           AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient") 
+        """ 
+        super(AsyncHTTPClient, cls).configure(impl, **kwargs) 
+ 
+ 
+class HTTPRequest(object): 
+    """HTTP client request object.""" 
+ 
+    # Default values for HTTPRequest parameters. 
+    # Merged with the values on the request object by AsyncHTTPClient 
+    # implementations. 
+    _DEFAULTS = dict( 
+        connect_timeout=20.0, 
+        request_timeout=20.0, 
+        follow_redirects=True, 
+        max_redirects=5, 
+        decompress_response=True, 
+        proxy_password='', 
+        allow_nonstandard_methods=False, 
+        validate_cert=True) 
+ 
+    def __init__(self, url, method="GET", headers=None, body=None, 
+                 auth_username=None, auth_password=None, auth_mode=None, 
+                 connect_timeout=None, request_timeout=None, 
+                 if_modified_since=None, follow_redirects=None, 
+                 max_redirects=None, user_agent=None, use_gzip=None, 
+                 network_interface=None, streaming_callback=None, 
+                 header_callback=None, prepare_curl_callback=None, 
+                 proxy_host=None, proxy_port=None, proxy_username=None, 
+                 proxy_password=None, proxy_auth_mode=None, 
+                 allow_nonstandard_methods=None, validate_cert=None, 
+                 ca_certs=None, allow_ipv6=None, client_key=None, 
+                 client_cert=None, body_producer=None, 
+                 expect_100_continue=False, decompress_response=None, 
+                 ssl_options=None): 
+        r"""All parameters except ``url`` are optional. 
+ 
+        :arg string url: URL to fetch 
+        :arg string method: HTTP method, e.g. "GET" or "POST" 
+        :arg headers: Additional HTTP headers to pass on the request 
+        :type headers: `~tornado.httputil.HTTPHeaders` or `dict` 
+        :arg body: HTTP request body as a string (byte or unicode; if unicode 
+           the utf-8 encoding will be used) 
+        :arg body_producer: Callable used for lazy/asynchronous request bodies. 
+           It is called with one argument, a ``write`` function, and should 
+           return a `.Future`.  It should call the write function with new 
+           data as it becomes available.  The write function returns a 
+           `.Future` which can be used for flow control. 
+           Only one of ``body`` and ``body_producer`` may 
+           be specified.  ``body_producer`` is not supported on 
+           ``curl_httpclient``.  When using ``body_producer`` it is recommended 
+           to pass a ``Content-Length`` in the headers as otherwise chunked 
+           encoding will be used, and many servers do not support chunked 
+           encoding on requests.  New in Tornado 4.0 
+        :arg string auth_username: Username for HTTP authentication 
+        :arg string auth_password: Password for HTTP authentication 
+        :arg string auth_mode: Authentication mode; default is "basic". 
+           Allowed values are implementation-defined; ``curl_httpclient`` 
+           supports "basic" and "digest"; ``simple_httpclient`` only supports 
+           "basic" 
+        :arg float connect_timeout: Timeout for initial connection in seconds, 
+           default 20 seconds 
+        :arg float request_timeout: Timeout for entire request in seconds, 
+           default 20 seconds 
+        :arg if_modified_since: Timestamp for ``If-Modified-Since`` header 
+        :type if_modified_since: `datetime` or `float` 
+        :arg bool follow_redirects: Should redirects be followed automatically 
+           or return the 3xx response? Default True. 
+        :arg int max_redirects: Limit for ``follow_redirects``, default 5. 
+        :arg string user_agent: String to send as ``User-Agent`` header 
+        :arg bool decompress_response: Request a compressed response from 
+           the server and decompress it after downloading.  Default is True. 
+           New in Tornado 4.0. 
+        :arg bool use_gzip: Deprecated alias for ``decompress_response`` 
+           since Tornado 4.0. 
+        :arg string network_interface: Network interface to use for request. 
+           ``curl_httpclient`` only; see note below. 
+        :arg callable streaming_callback: If set, ``streaming_callback`` will 
+           be run with each chunk of data as it is received, and 
+           ``HTTPResponse.body`` and ``HTTPResponse.buffer`` will be empty in 
+           the final response. 
+        :arg callable header_callback: If set, ``header_callback`` will 
+           be run with each header line as it is received (including the 
+           first line, e.g. ``HTTP/1.0 200 OK\r\n``, and a final line 
+           containing only ``\r\n``.  All lines include the trailing newline 
+           characters).  ``HTTPResponse.headers`` will be empty in the final 
+           response.  This is most useful in conjunction with 
+           ``streaming_callback``, because it's the only way to get access to 
+           header data while the request is in progress. 
+        :arg callable prepare_curl_callback: If set, will be called with 
+           a ``pycurl.Curl`` object to allow the application to make additional 
+           ``setopt`` calls. 
+        :arg string proxy_host: HTTP proxy hostname.  To use proxies, 
+           ``proxy_host`` and ``proxy_port`` must be set; ``proxy_username``, 
+           ``proxy_pass`` and ``proxy_auth_mode`` are optional.  Proxies are 
+           currently only supported with ``curl_httpclient``. 
+        :arg int proxy_port: HTTP proxy port 
+        :arg string proxy_username: HTTP proxy username 
+        :arg string proxy_password: HTTP proxy password 
+        :arg string proxy_auth_mode: HTTP proxy Authentication mode; 
+           default is "basic". supports "basic" and "digest" 
+        :arg bool allow_nonstandard_methods: Allow unknown values for ``method`` 
+           argument? Default is False. 
+        :arg bool validate_cert: For HTTPS requests, validate the server's 
+           certificate? Default is True. 
+        :arg string ca_certs: filename of CA certificates in PEM format, 
+           or None to use defaults.  See note below when used with 
+           ``curl_httpclient``. 
+        :arg string client_key: Filename for client SSL key, if any.  See 
+           note below when used with ``curl_httpclient``. 
+        :arg string client_cert: Filename for client SSL certificate, if any. 
+           See note below when used with ``curl_httpclient``. 
+        :arg ssl.SSLContext ssl_options: `ssl.SSLContext` object for use in 
+           ``simple_httpclient`` (unsupported by ``curl_httpclient``). 
+           Overrides ``validate_cert``, ``ca_certs``, ``client_key``, 
+           and ``client_cert``. 
+        :arg bool allow_ipv6: Use IPv6 when available?  Default is true. 
+        :arg bool expect_100_continue: If true, send the 
+           ``Expect: 100-continue`` header and wait for a continue response 
+           before sending the request body.  Only supported with 
+           simple_httpclient. 
+ 
+        .. note:: 
+ 
+            When using ``curl_httpclient`` certain options may be 
+            inherited by subsequent fetches because ``pycurl`` does 
+            not allow them to be cleanly reset.  This applies to the 
+            ``ca_certs``, ``client_key``, ``client_cert``, and 
+            ``network_interface`` arguments.  If you use these 
+            options, you should pass them on every request (you don't 
+            have to always use the same values, but it's not possible 
+            to mix requests that specify these options with ones that 
+            use the defaults). 
+ 
+        .. versionadded:: 3.1 
+           The ``auth_mode`` argument. 
+ 
+        .. versionadded:: 4.0 
+           The ``body_producer`` and ``expect_100_continue`` arguments. 
+ 
+        .. versionadded:: 4.2 
+           The ``ssl_options`` argument. 
+ 
+        .. versionadded:: 4.5 
+           The ``proxy_auth_mode`` argument. 
+        """ 
+        # Note that some of these attributes go through property setters 
+        # defined below. 
+        self.headers = headers 
+        if if_modified_since: 
+            self.headers["If-Modified-Since"] = httputil.format_timestamp( 
+                if_modified_since) 
+        self.proxy_host = proxy_host 
+        self.proxy_port = proxy_port 
+        self.proxy_username = proxy_username 
+        self.proxy_password = proxy_password 
+        self.proxy_auth_mode = proxy_auth_mode 
+        self.url = url 
+        self.method = method 
+        self.body = body 
+        self.body_producer = body_producer 
+        self.auth_username = auth_username 
+        self.auth_password = auth_password 
+        self.auth_mode = auth_mode 
+        self.connect_timeout = connect_timeout 
+        self.request_timeout = request_timeout 
+        self.follow_redirects = follow_redirects 
+        self.max_redirects = max_redirects 
+        self.user_agent = user_agent 
+        if decompress_response is not None: 
+            self.decompress_response = decompress_response 
+        else: 
+            self.decompress_response = use_gzip 
+        self.network_interface = network_interface 
+        self.streaming_callback = streaming_callback 
+        self.header_callback = header_callback 
+        self.prepare_curl_callback = prepare_curl_callback 
+        self.allow_nonstandard_methods = allow_nonstandard_methods 
+        self.validate_cert = validate_cert 
+        self.ca_certs = ca_certs 
+        self.allow_ipv6 = allow_ipv6 
+        self.client_key = client_key 
+        self.client_cert = client_cert 
+        self.ssl_options = ssl_options 
+        self.expect_100_continue = expect_100_continue 
+        self.start_time = time.time() 
+ 
+    @property 
+    def headers(self): 
+        return self._headers 
+ 
+    @headers.setter 
+    def headers(self, value): 
+        if value is None: 
+            self._headers = httputil.HTTPHeaders() 
+        else: 
+            self._headers = value 
+ 
+    @property 
+    def body(self): 
+        return self._body 
+ 
+    @body.setter 
+    def body(self, value): 
+        self._body = utf8(value) 
+ 
+    @property 
+    def body_producer(self): 
+        return self._body_producer 
+ 
+    @body_producer.setter 
+    def body_producer(self, value): 
+        self._body_producer = stack_context.wrap(value) 
+ 
+    @property 
+    def streaming_callback(self): 
+        return self._streaming_callback 
+ 
+    @streaming_callback.setter 
+    def streaming_callback(self, value): 
+        self._streaming_callback = stack_context.wrap(value) 
+ 
+    @property 
+    def header_callback(self): 
+        return self._header_callback 
+ 
+    @header_callback.setter 
+    def header_callback(self, value): 
+        self._header_callback = stack_context.wrap(value) 
+ 
+    @property 
+    def prepare_curl_callback(self): 
+        return self._prepare_curl_callback 
+ 
+    @prepare_curl_callback.setter 
+    def prepare_curl_callback(self, value): 
+        self._prepare_curl_callback = stack_context.wrap(value) 
+ 
+ 
+class HTTPResponse(object): 
+    """HTTP Response object. 
+ 
+    Attributes: 
+ 
+    * request: HTTPRequest object 
+ 
+    * code: numeric HTTP status code, e.g. 200 or 404 
+ 
+    * reason: human-readable reason phrase describing the status code 
+ 
+    * headers: `tornado.httputil.HTTPHeaders` object 
+ 
+    * effective_url: final location of the resource after following any 
+      redirects 
+ 
+    * buffer: ``cStringIO`` object for response body 
+ 
+    * body: response body as bytes (created on demand from ``self.buffer``) 
+ 
+    * error: Exception object, if any 
+ 
+    * request_time: seconds from request start to finish 
+ 
+    * time_info: dictionary of diagnostic timing information from the request. 
+      Available data are subject to change, but currently uses timings 
+      available from http://curl.haxx.se/libcurl/c/curl_easy_getinfo.html, 
+      plus ``queue``, which is the delay (if any) introduced by waiting for 
+      a slot under `AsyncHTTPClient`'s ``max_clients`` setting. 
+    """ 
+    def __init__(self, request, code, headers=None, buffer=None, 
+                 effective_url=None, error=None, request_time=None, 
+                 time_info=None, reason=None): 
+        if isinstance(request, _RequestProxy): 
+            self.request = request.request 
+        else: 
+            self.request = request 
+        self.code = code 
+        self.reason = reason or httputil.responses.get(code, "Unknown") 
+        if headers is not None: 
+            self.headers = headers 
+        else: 
+            self.headers = httputil.HTTPHeaders() 
+        self.buffer = buffer 
+        self._body = None 
+        if effective_url is None: 
+            self.effective_url = request.url 
+        else: 
+            self.effective_url = effective_url 
+        if error is None: 
+            if self.code < 200 or self.code >= 300: 
+                self.error = HTTPError(self.code, message=self.reason, 
+                                       response=self) 
+            else: 
+                self.error = None 
+        else: 
+            self.error = error 
+        self.request_time = request_time 
+        self.time_info = time_info or {} 
+ 
+    @property 
+    def body(self): 
+        if self.buffer is None: 
+            return None 
+        elif self._body is None: 
+            self._body = self.buffer.getvalue() 
+ 
+        return self._body 
+ 
+    def rethrow(self): 
+        """If there was an error on the request, raise an `HTTPError`.""" 
+        if self.error: 
+            raise self.error 
+ 
+    def __repr__(self): 
+        args = ",".join("%s=%r" % i for i in sorted(self.__dict__.items())) 
+        return "%s(%s)" % (self.__class__.__name__, args) 
+ 
+ 
+class HTTPError(Exception): 
+    """Exception thrown for an unsuccessful HTTP request. 
+ 
+    Attributes: 
+ 
+    * ``code`` - HTTP error integer error code, e.g. 404.  Error code 599 is 
+      used when no HTTP response was received, e.g. for a timeout. 
+ 
+    * ``response`` - `HTTPResponse` object, if any. 
+ 
+    Note that if ``follow_redirects`` is False, redirects become HTTPErrors, 
+    and you can look at ``error.response.headers['Location']`` to see the 
+    destination of the redirect. 
+    """ 
+    def __init__(self, code, message=None, response=None): 
+        self.code = code 
+        self.message = message or httputil.responses.get(code, "Unknown") 
+        self.response = response 
+        super(HTTPError, self).__init__(code, message, response) 
+ 
+    def __str__(self): 
+        return "HTTP %d: %s" % (self.code, self.message) 
+ 
+    # There is a cyclic reference between self and self.response, 
+    # which breaks the default __repr__ implementation. 
+    # (especially on pypy, which doesn't have the same recursion 
+    # detection as cpython). 
+    __repr__ = __str__ 
+ 
+ 
+class _RequestProxy(object): 
+    """Combines an object with a dictionary of defaults. 
+ 
+    Used internally by AsyncHTTPClient implementations. 
+    """ 
+    def __init__(self, request, defaults): 
+        self.request = request 
+        self.defaults = defaults 
+ 
+    def __getattr__(self, name): 
+        request_attr = getattr(self.request, name) 
+        if request_attr is not None: 
+            return request_attr 
+        elif self.defaults is not None: 
+            return self.defaults.get(name, None) 
+        else: 
+            return None 
+ 
+ 
+def main(): 
+    from tornado.options import define, options, parse_command_line 
+    define("print_headers", type=bool, default=False) 
+    define("print_body", type=bool, default=True) 
+    define("follow_redirects", type=bool, default=True) 
+    define("validate_cert", type=bool, default=True) 
+    args = parse_command_line() 
+    client = HTTPClient() 
+    for arg in args: 
+        try: 
+            response = client.fetch(arg, 
+                                    follow_redirects=options.follow_redirects, 
+                                    validate_cert=options.validate_cert, 
+                                    ) 
+        except HTTPError as e: 
+            if e.response is not None: 
+                response = e.response 
+            else: 
+                raise 
+        if options.print_headers: 
+            print(response.headers) 
+        if options.print_body: 
+            print(native_str(response.body)) 
+    client.close() 
+ 
+ 
+if __name__ == "__main__": 
+    main() 
diff --git a/contrib/python/tornado/tornado-4/tornado/httpserver.py b/contrib/python/tornado/tornado-4/tornado/httpserver.py
index d757be188d..90fb01b8d6 100644
--- a/contrib/python/tornado/tornado-4/tornado/httpserver.py
+++ b/contrib/python/tornado/tornado-4/tornado/httpserver.py
@@ -1,325 +1,325 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""A non-blocking, single-threaded HTTP server.
-
-Typical applications have little direct interaction with the `HTTPServer`
-class except to start a server at the beginning of the process
-(and even that is often done indirectly via `tornado.web.Application.listen`).
-
-.. versionchanged:: 4.0
-
-   The ``HTTPRequest`` class that used to live in this module has been moved
-   to `tornado.httputil.HTTPServerRequest`.  The old name remains as an alias.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import socket
-
-from tornado.escape import native_str
-from tornado.http1connection import HTTP1ServerConnection, HTTP1ConnectionParameters
-from tornado import gen
-from tornado import httputil
-from tornado import iostream
-from tornado import netutil
-from tornado.tcpserver import TCPServer
-from tornado.util import Configurable
-
-
-class HTTPServer(TCPServer, Configurable,
-                 httputil.HTTPServerConnectionDelegate):
-    r"""A non-blocking, single-threaded HTTP server.
-
-    A server is defined by a subclass of `.HTTPServerConnectionDelegate`,
-    or, for backwards compatibility, a callback that takes an
-    `.HTTPServerRequest` as an argument. The delegate is usually a
-    `tornado.web.Application`.
-
-    `HTTPServer` supports keep-alive connections by default
-    (automatically for HTTP/1.1, or for HTTP/1.0 when the client
-    requests ``Connection: keep-alive``).
-
-    If ``xheaders`` is ``True``, we support the
-    ``X-Real-Ip``/``X-Forwarded-For`` and
-    ``X-Scheme``/``X-Forwarded-Proto`` headers, which override the
-    remote IP and URI scheme/protocol for all requests.  These headers
-    are useful when running Tornado behind a reverse proxy or load
-    balancer.  The ``protocol`` argument can also be set to ``https``
-    if Tornado is run behind an SSL-decoding proxy that does not set one of
-    the supported ``xheaders``.
-
-    By default, when parsing the ``X-Forwarded-For`` header, Tornado will
-    select the last (i.e., the closest) address on the list of hosts as the
-    remote host IP address.  To select the next server in the chain, a list of
-    trusted downstream hosts may be passed as the ``trusted_downstream``
-    argument.  These hosts will be skipped when parsing the ``X-Forwarded-For``
-    header.
-
-    To make this server serve SSL traffic, send the ``ssl_options`` keyword
-    argument with an `ssl.SSLContext` object. For compatibility with older
-    versions of Python ``ssl_options`` may also be a dictionary of keyword
-    arguments for the `ssl.wrap_socket` method.::
-
-       ssl_ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
-       ssl_ctx.load_cert_chain(os.path.join(data_dir, "mydomain.crt"),
-                               os.path.join(data_dir, "mydomain.key"))
-       HTTPServer(applicaton, ssl_options=ssl_ctx)
-
-    `HTTPServer` initialization follows one of three patterns (the
-    initialization methods are defined on `tornado.tcpserver.TCPServer`):
-
-    1. `~tornado.tcpserver.TCPServer.listen`: simple single-process::
-
-            server = HTTPServer(app)
-            server.listen(8888)
-            IOLoop.current().start()
-
-       In many cases, `tornado.web.Application.listen` can be used to avoid
-       the need to explicitly create the `HTTPServer`.
-
-    2. `~tornado.tcpserver.TCPServer.bind`/`~tornado.tcpserver.TCPServer.start`:
-       simple multi-process::
-
-            server = HTTPServer(app)
-            server.bind(8888)
-            server.start(0)  # Forks multiple sub-processes
-            IOLoop.current().start()
-
-       When using this interface, an `.IOLoop` must *not* be passed
-       to the `HTTPServer` constructor.  `~.TCPServer.start` will always start
-       the server on the default singleton `.IOLoop`.
-
-    3. `~tornado.tcpserver.TCPServer.add_sockets`: advanced multi-process::
-
-            sockets = tornado.netutil.bind_sockets(8888)
-            tornado.process.fork_processes(0)
-            server = HTTPServer(app)
-            server.add_sockets(sockets)
-            IOLoop.current().start()
-
-       The `~.TCPServer.add_sockets` interface is more complicated,
-       but it can be used with `tornado.process.fork_processes` to
-       give you more flexibility in when the fork happens.
-       `~.TCPServer.add_sockets` can also be used in single-process
-       servers if you want to create your listening sockets in some
-       way other than `tornado.netutil.bind_sockets`.
-
-    .. versionchanged:: 4.0
-       Added ``decompress_request``, ``chunk_size``, ``max_header_size``,
-       ``idle_connection_timeout``, ``body_timeout``, ``max_body_size``
-       arguments.  Added support for `.HTTPServerConnectionDelegate`
-       instances as ``request_callback``.
-
-    .. versionchanged:: 4.1
-       `.HTTPServerConnectionDelegate.start_request` is now called with
-       two arguments ``(server_conn, request_conn)`` (in accordance with the
-       documentation) instead of one ``(request_conn)``.
-
-    .. versionchanged:: 4.2
-       `HTTPServer` is now a subclass of `tornado.util.Configurable`.
-
-    .. versionchanged:: 4.5
-       Added the ``trusted_downstream`` argument.
-    """
-    def __init__(self, *args, **kwargs):
-        # Ignore args to __init__; real initialization belongs in
-        # initialize since we're Configurable. (there's something
-        # weird in initialization order between this class,
-        # Configurable, and TCPServer so we can't leave __init__ out
-        # completely)
-        pass
-
-    def initialize(self, request_callback, no_keep_alive=False, io_loop=None,
-                   xheaders=False, ssl_options=None, protocol=None,
-                   decompress_request=False,
-                   chunk_size=None, max_header_size=None,
-                   idle_connection_timeout=None, body_timeout=None,
-                   max_body_size=None, max_buffer_size=None,
-                   trusted_downstream=None):
-        self.request_callback = request_callback
-        self.no_keep_alive = no_keep_alive
-        self.xheaders = xheaders
-        self.protocol = protocol
-        self.conn_params = HTTP1ConnectionParameters(
-            decompress=decompress_request,
-            chunk_size=chunk_size,
-            max_header_size=max_header_size,
-            header_timeout=idle_connection_timeout or 3600,
-            max_body_size=max_body_size,
-            body_timeout=body_timeout,
-            no_keep_alive=no_keep_alive)
-        TCPServer.__init__(self, io_loop=io_loop, ssl_options=ssl_options,
-                           max_buffer_size=max_buffer_size,
-                           read_chunk_size=chunk_size)
-        self._connections = set()
-        self.trusted_downstream = trusted_downstream
-
-    @classmethod
-    def configurable_base(cls):
-        return HTTPServer
-
-    @classmethod
-    def configurable_default(cls):
-        return HTTPServer
-
-    @gen.coroutine
-    def close_all_connections(self):
-        while self._connections:
-            # Peek at an arbitrary element of the set
-            conn = next(iter(self._connections))
-            yield conn.close()
-
-    def handle_stream(self, stream, address):
-        context = _HTTPRequestContext(stream, address,
-                                      self.protocol,
-                                      self.trusted_downstream)
-        conn = HTTP1ServerConnection(
-            stream, self.conn_params, context)
-        self._connections.add(conn)
-        conn.start_serving(self)
-
-    def start_request(self, server_conn, request_conn):
-        if isinstance(self.request_callback, httputil.HTTPServerConnectionDelegate):
-            delegate = self.request_callback.start_request(server_conn, request_conn)
-        else:
-            delegate = _CallableAdapter(self.request_callback, request_conn)
-
-        if self.xheaders:
-            delegate = _ProxyAdapter(delegate, request_conn)
-
-        return delegate
-
-    def on_close(self, server_conn):
-        self._connections.remove(server_conn)
-
-
-class _CallableAdapter(httputil.HTTPMessageDelegate):
-    def __init__(self, request_callback, request_conn):
-        self.connection = request_conn
-        self.request_callback = request_callback
-        self.request = None
-        self.delegate = None
-        self._chunks = []
-
-    def headers_received(self, start_line, headers):
-        self.request = httputil.HTTPServerRequest(
-            connection=self.connection, start_line=start_line,
-            headers=headers)
-
-    def data_received(self, chunk):
-        self._chunks.append(chunk)
-
-    def finish(self):
-        self.request.body = b''.join(self._chunks)
-        self.request._parse_body()
-        self.request_callback(self.request)
-
-    def on_connection_close(self):
-        self._chunks = None
-
-
-class _HTTPRequestContext(object):
-    def __init__(self, stream, address, protocol, trusted_downstream=None):
-        self.address = address
-        # Save the socket's address family now so we know how to
-        # interpret self.address even after the stream is closed
-        # and its socket attribute replaced with None.
-        if stream.socket is not None:
-            self.address_family = stream.socket.family
-        else:
-            self.address_family = None
-        # In HTTPServerRequest we want an IP, not a full socket address.
-        if (self.address_family in (socket.AF_INET, socket.AF_INET6) and
-                address is not None):
-            self.remote_ip = address[0]
-        else:
-            # Unix (or other) socket; fake the remote address.
-            self.remote_ip = '0.0.0.0'
-        if protocol:
-            self.protocol = protocol
-        elif isinstance(stream, iostream.SSLIOStream):
-            self.protocol = "https"
-        else:
-            self.protocol = "http"
-        self._orig_remote_ip = self.remote_ip
-        self._orig_protocol = self.protocol
-        self.trusted_downstream = set(trusted_downstream or [])
-
-    def __str__(self):
-        if self.address_family in (socket.AF_INET, socket.AF_INET6):
-            return self.remote_ip
-        elif isinstance(self.address, bytes):
-            # Python 3 with the -bb option warns about str(bytes),
-            # so convert it explicitly.
-            # Unix socket addresses are str on mac but bytes on linux.
-            return native_str(self.address)
-        else:
-            return str(self.address)
-
-    def _apply_xheaders(self, headers):
-        """Rewrite the ``remote_ip`` and ``protocol`` fields."""
-        # Squid uses X-Forwarded-For, others use X-Real-Ip
-        ip = headers.get("X-Forwarded-For", self.remote_ip)
-        # Skip trusted downstream hosts in X-Forwarded-For list
-        for ip in (cand.strip() for cand in reversed(ip.split(','))):
-            if ip not in self.trusted_downstream:
-                break
-        ip = headers.get("X-Real-Ip", ip)
-        if netutil.is_valid_ip(ip):
-            self.remote_ip = ip
-        # AWS uses X-Forwarded-Proto
-        proto_header = headers.get(
-            "X-Scheme", headers.get("X-Forwarded-Proto",
-                                    self.protocol))
-        if proto_header in ("http", "https"):
-            self.protocol = proto_header
-
-    def _unapply_xheaders(self):
-        """Undo changes from `_apply_xheaders`.
-
-        Xheaders are per-request so they should not leak to the next
-        request on the same connection.
-        """
-        self.remote_ip = self._orig_remote_ip
-        self.protocol = self._orig_protocol
-
-
-class _ProxyAdapter(httputil.HTTPMessageDelegate):
-    def __init__(self, delegate, request_conn):
-        self.connection = request_conn
-        self.delegate = delegate
-
-    def headers_received(self, start_line, headers):
-        self.connection.context._apply_xheaders(headers)
-        return self.delegate.headers_received(start_line, headers)
-
-    def data_received(self, chunk):
-        return self.delegate.data_received(chunk)
-
-    def finish(self):
-        self.delegate.finish()
-        self._cleanup()
-
-    def on_connection_close(self):
-        self.delegate.on_connection_close()
-        self._cleanup()
-
-    def _cleanup(self):
-        self.connection.context._unapply_xheaders()
-
-
-HTTPRequest = httputil.HTTPServerRequest
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""A non-blocking, single-threaded HTTP server. 
+ 
+Typical applications have little direct interaction with the `HTTPServer` 
+class except to start a server at the beginning of the process 
+(and even that is often done indirectly via `tornado.web.Application.listen`). 
+ 
+.. versionchanged:: 4.0 
+ 
+   The ``HTTPRequest`` class that used to live in this module has been moved 
+   to `tornado.httputil.HTTPServerRequest`.  The old name remains as an alias. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import socket 
+ 
+from tornado.escape import native_str 
+from tornado.http1connection import HTTP1ServerConnection, HTTP1ConnectionParameters 
+from tornado import gen 
+from tornado import httputil 
+from tornado import iostream 
+from tornado import netutil 
+from tornado.tcpserver import TCPServer 
+from tornado.util import Configurable 
+ 
+ 
+class HTTPServer(TCPServer, Configurable, 
+                 httputil.HTTPServerConnectionDelegate): 
+    r"""A non-blocking, single-threaded HTTP server. 
+ 
+    A server is defined by a subclass of `.HTTPServerConnectionDelegate`, 
+    or, for backwards compatibility, a callback that takes an 
+    `.HTTPServerRequest` as an argument. The delegate is usually a 
+    `tornado.web.Application`. 
+ 
+    `HTTPServer` supports keep-alive connections by default 
+    (automatically for HTTP/1.1, or for HTTP/1.0 when the client 
+    requests ``Connection: keep-alive``). 
+ 
+    If ``xheaders`` is ``True``, we support the 
+    ``X-Real-Ip``/``X-Forwarded-For`` and 
+    ``X-Scheme``/``X-Forwarded-Proto`` headers, which override the 
+    remote IP and URI scheme/protocol for all requests.  These headers 
+    are useful when running Tornado behind a reverse proxy or load 
+    balancer.  The ``protocol`` argument can also be set to ``https`` 
+    if Tornado is run behind an SSL-decoding proxy that does not set one of 
+    the supported ``xheaders``. 
+ 
+    By default, when parsing the ``X-Forwarded-For`` header, Tornado will 
+    select the last (i.e., the closest) address on the list of hosts as the 
+    remote host IP address.  To select the next server in the chain, a list of 
+    trusted downstream hosts may be passed as the ``trusted_downstream`` 
+    argument.  These hosts will be skipped when parsing the ``X-Forwarded-For`` 
+    header. 
+ 
+    To make this server serve SSL traffic, send the ``ssl_options`` keyword 
+    argument with an `ssl.SSLContext` object. For compatibility with older 
+    versions of Python ``ssl_options`` may also be a dictionary of keyword 
+    arguments for the `ssl.wrap_socket` method.:: 
+ 
+       ssl_ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH) 
+       ssl_ctx.load_cert_chain(os.path.join(data_dir, "mydomain.crt"), 
+                               os.path.join(data_dir, "mydomain.key")) 
+       HTTPServer(applicaton, ssl_options=ssl_ctx) 
+ 
+    `HTTPServer` initialization follows one of three patterns (the 
+    initialization methods are defined on `tornado.tcpserver.TCPServer`): 
+ 
+    1. `~tornado.tcpserver.TCPServer.listen`: simple single-process:: 
+ 
+            server = HTTPServer(app) 
+            server.listen(8888) 
+            IOLoop.current().start() 
+ 
+       In many cases, `tornado.web.Application.listen` can be used to avoid 
+       the need to explicitly create the `HTTPServer`. 
+ 
+    2. `~tornado.tcpserver.TCPServer.bind`/`~tornado.tcpserver.TCPServer.start`: 
+       simple multi-process:: 
+ 
+            server = HTTPServer(app) 
+            server.bind(8888) 
+            server.start(0)  # Forks multiple sub-processes 
+            IOLoop.current().start() 
+ 
+       When using this interface, an `.IOLoop` must *not* be passed 
+       to the `HTTPServer` constructor.  `~.TCPServer.start` will always start 
+       the server on the default singleton `.IOLoop`. 
+ 
+    3. `~tornado.tcpserver.TCPServer.add_sockets`: advanced multi-process:: 
+ 
+            sockets = tornado.netutil.bind_sockets(8888) 
+            tornado.process.fork_processes(0) 
+            server = HTTPServer(app) 
+            server.add_sockets(sockets) 
+            IOLoop.current().start() 
+ 
+       The `~.TCPServer.add_sockets` interface is more complicated, 
+       but it can be used with `tornado.process.fork_processes` to 
+       give you more flexibility in when the fork happens. 
+       `~.TCPServer.add_sockets` can also be used in single-process 
+       servers if you want to create your listening sockets in some 
+       way other than `tornado.netutil.bind_sockets`. 
+ 
+    .. versionchanged:: 4.0 
+       Added ``decompress_request``, ``chunk_size``, ``max_header_size``, 
+       ``idle_connection_timeout``, ``body_timeout``, ``max_body_size`` 
+       arguments.  Added support for `.HTTPServerConnectionDelegate` 
+       instances as ``request_callback``. 
+ 
+    .. versionchanged:: 4.1 
+       `.HTTPServerConnectionDelegate.start_request` is now called with 
+       two arguments ``(server_conn, request_conn)`` (in accordance with the 
+       documentation) instead of one ``(request_conn)``. 
+ 
+    .. versionchanged:: 4.2 
+       `HTTPServer` is now a subclass of `tornado.util.Configurable`. 
+ 
+    .. versionchanged:: 4.5 
+       Added the ``trusted_downstream`` argument. 
+    """ 
+    def __init__(self, *args, **kwargs): 
+        # Ignore args to __init__; real initialization belongs in 
+        # initialize since we're Configurable. (there's something 
+        # weird in initialization order between this class, 
+        # Configurable, and TCPServer so we can't leave __init__ out 
+        # completely) 
+        pass 
+ 
+    def initialize(self, request_callback, no_keep_alive=False, io_loop=None, 
+                   xheaders=False, ssl_options=None, protocol=None, 
+                   decompress_request=False, 
+                   chunk_size=None, max_header_size=None, 
+                   idle_connection_timeout=None, body_timeout=None, 
+                   max_body_size=None, max_buffer_size=None, 
+                   trusted_downstream=None): 
+        self.request_callback = request_callback 
+        self.no_keep_alive = no_keep_alive 
+        self.xheaders = xheaders 
+        self.protocol = protocol 
+        self.conn_params = HTTP1ConnectionParameters( 
+            decompress=decompress_request, 
+            chunk_size=chunk_size, 
+            max_header_size=max_header_size, 
+            header_timeout=idle_connection_timeout or 3600, 
+            max_body_size=max_body_size, 
+            body_timeout=body_timeout, 
+            no_keep_alive=no_keep_alive) 
+        TCPServer.__init__(self, io_loop=io_loop, ssl_options=ssl_options, 
+                           max_buffer_size=max_buffer_size, 
+                           read_chunk_size=chunk_size) 
+        self._connections = set() 
+        self.trusted_downstream = trusted_downstream 
+ 
+    @classmethod 
+    def configurable_base(cls): 
+        return HTTPServer 
+ 
+    @classmethod 
+    def configurable_default(cls): 
+        return HTTPServer 
+ 
+    @gen.coroutine 
+    def close_all_connections(self): 
+        while self._connections: 
+            # Peek at an arbitrary element of the set 
+            conn = next(iter(self._connections)) 
+            yield conn.close() 
+ 
+    def handle_stream(self, stream, address): 
+        context = _HTTPRequestContext(stream, address, 
+                                      self.protocol, 
+                                      self.trusted_downstream) 
+        conn = HTTP1ServerConnection( 
+            stream, self.conn_params, context) 
+        self._connections.add(conn) 
+        conn.start_serving(self) 
+ 
+    def start_request(self, server_conn, request_conn): 
+        if isinstance(self.request_callback, httputil.HTTPServerConnectionDelegate): 
+            delegate = self.request_callback.start_request(server_conn, request_conn) 
+        else: 
+            delegate = _CallableAdapter(self.request_callback, request_conn) 
+ 
+        if self.xheaders: 
+            delegate = _ProxyAdapter(delegate, request_conn) 
+ 
+        return delegate 
+ 
+    def on_close(self, server_conn): 
+        self._connections.remove(server_conn) 
+ 
+ 
+class _CallableAdapter(httputil.HTTPMessageDelegate): 
+    def __init__(self, request_callback, request_conn): 
+        self.connection = request_conn 
+        self.request_callback = request_callback 
+        self.request = None 
+        self.delegate = None 
+        self._chunks = [] 
+ 
+    def headers_received(self, start_line, headers): 
+        self.request = httputil.HTTPServerRequest( 
+            connection=self.connection, start_line=start_line, 
+            headers=headers) 
+ 
+    def data_received(self, chunk): 
+        self._chunks.append(chunk) 
+ 
+    def finish(self): 
+        self.request.body = b''.join(self._chunks) 
+        self.request._parse_body() 
+        self.request_callback(self.request) 
+ 
+    def on_connection_close(self): 
+        self._chunks = None 
+ 
+ 
+class _HTTPRequestContext(object): 
+    def __init__(self, stream, address, protocol, trusted_downstream=None): 
+        self.address = address 
+        # Save the socket's address family now so we know how to 
+        # interpret self.address even after the stream is closed 
+        # and its socket attribute replaced with None. 
+        if stream.socket is not None: 
+            self.address_family = stream.socket.family 
+        else: 
+            self.address_family = None 
+        # In HTTPServerRequest we want an IP, not a full socket address. 
+        if (self.address_family in (socket.AF_INET, socket.AF_INET6) and 
+                address is not None): 
+            self.remote_ip = address[0] 
+        else: 
+            # Unix (or other) socket; fake the remote address. 
+            self.remote_ip = '0.0.0.0' 
+        if protocol: 
+            self.protocol = protocol 
+        elif isinstance(stream, iostream.SSLIOStream): 
+            self.protocol = "https" 
+        else: 
+            self.protocol = "http" 
+        self._orig_remote_ip = self.remote_ip 
+        self._orig_protocol = self.protocol 
+        self.trusted_downstream = set(trusted_downstream or []) 
+ 
+    def __str__(self): 
+        if self.address_family in (socket.AF_INET, socket.AF_INET6): 
+            return self.remote_ip 
+        elif isinstance(self.address, bytes): 
+            # Python 3 with the -bb option warns about str(bytes), 
+            # so convert it explicitly. 
+            # Unix socket addresses are str on mac but bytes on linux. 
+            return native_str(self.address) 
+        else: 
+            return str(self.address) 
+ 
+    def _apply_xheaders(self, headers): 
+        """Rewrite the ``remote_ip`` and ``protocol`` fields.""" 
+        # Squid uses X-Forwarded-For, others use X-Real-Ip 
+        ip = headers.get("X-Forwarded-For", self.remote_ip) 
+        # Skip trusted downstream hosts in X-Forwarded-For list 
+        for ip in (cand.strip() for cand in reversed(ip.split(','))): 
+            if ip not in self.trusted_downstream: 
+                break 
+        ip = headers.get("X-Real-Ip", ip) 
+        if netutil.is_valid_ip(ip): 
+            self.remote_ip = ip 
+        # AWS uses X-Forwarded-Proto 
+        proto_header = headers.get( 
+            "X-Scheme", headers.get("X-Forwarded-Proto", 
+                                    self.protocol)) 
+        if proto_header in ("http", "https"): 
+            self.protocol = proto_header 
+ 
+    def _unapply_xheaders(self): 
+        """Undo changes from `_apply_xheaders`. 
+ 
+        Xheaders are per-request so they should not leak to the next 
+        request on the same connection. 
+        """ 
+        self.remote_ip = self._orig_remote_ip 
+        self.protocol = self._orig_protocol 
+ 
+ 
+class _ProxyAdapter(httputil.HTTPMessageDelegate): 
+    def __init__(self, delegate, request_conn): 
+        self.connection = request_conn 
+        self.delegate = delegate 
+ 
+    def headers_received(self, start_line, headers): 
+        self.connection.context._apply_xheaders(headers) 
+        return self.delegate.headers_received(start_line, headers) 
+ 
+    def data_received(self, chunk): 
+        return self.delegate.data_received(chunk) 
+ 
+    def finish(self): 
+        self.delegate.finish() 
+        self._cleanup() 
+ 
+    def on_connection_close(self): 
+        self.delegate.on_connection_close() 
+        self._cleanup() 
+ 
+    def _cleanup(self): 
+        self.connection.context._unapply_xheaders() 
+ 
+ 
+HTTPRequest = httputil.HTTPServerRequest 
diff --git a/contrib/python/tornado/tornado-4/tornado/httputil.py b/contrib/python/tornado/tornado-4/tornado/httputil.py
index 9654b5ab4b..8be39ebf2b 100644
--- a/contrib/python/tornado/tornado-4/tornado/httputil.py
+++ b/contrib/python/tornado/tornado-4/tornado/httputil.py
@@ -1,1026 +1,1026 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""HTTP utility code shared by clients and servers.
-
-This module also defines the `HTTPServerRequest` class which is exposed
-via `tornado.web.RequestHandler.request`.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import calendar
-import collections
-import copy
-import datetime
-import email.utils
-import numbers
-import re
-import time
-
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""HTTP utility code shared by clients and servers. 
+ 
+This module also defines the `HTTPServerRequest` class which is exposed 
+via `tornado.web.RequestHandler.request`. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import calendar 
+import collections 
+import copy 
+import datetime 
+import email.utils 
+import numbers 
+import re 
+import time 
+ 
 try:
     from collections.abc import MutableMapping
 except ImportError:
     from collections import MutableMapping
 
-from tornado.escape import native_str, parse_qs_bytes, utf8
-from tornado.log import gen_log
-from tornado.util import ObjectDict, PY3
-
-if PY3:
-    import http.cookies as Cookie
-    from http.client import responses
-    from urllib.parse import urlencode, urlparse, urlunparse, parse_qsl
-else:
-    import Cookie
-    from httplib import responses
-    from urllib import urlencode
-    from urlparse import urlparse, urlunparse, parse_qsl
-
-
-# responses is unused in this file, but we re-export it to other files.
-# Reference it so pyflakes doesn't complain.
-responses
-
-try:
-    from ssl import SSLError
-except ImportError:
-    # ssl is unavailable on app engine.
-    class _SSLError(Exception):
-        pass
-    # Hack around a mypy limitation. We can't simply put "type: ignore"
-    # on the class definition itself; must go through an assignment.
-    SSLError = _SSLError  # type: ignore
-
-try:
-    import typing
-except ImportError:
-    pass
-
-
-# RFC 7230 section 3.5: a recipient MAY recognize a single LF as a line
-# terminator and ignore any preceding CR.
-_CRLF_RE = re.compile(r'\r?\n')
-
-
-class _NormalizedHeaderCache(dict):
-    """Dynamic cached mapping of header names to Http-Header-Case.
-
-    Implemented as a dict subclass so that cache hits are as fast as a
-    normal dict lookup, without the overhead of a python function
-    call.
-
-    >>> normalized_headers = _NormalizedHeaderCache(10)
-    >>> normalized_headers["coNtent-TYPE"]
-    'Content-Type'
-    """
-    def __init__(self, size):
-        super(_NormalizedHeaderCache, self).__init__()
-        self.size = size
-        self.queue = collections.deque()
-
-    def __missing__(self, key):
-        normalized = "-".join([w.capitalize() for w in key.split("-")])
-        self[key] = normalized
-        self.queue.append(key)
-        if len(self.queue) > self.size:
-            # Limit the size of the cache.  LRU would be better, but this
-            # simpler approach should be fine.  In Python 2.7+ we could
-            # use OrderedDict (or in 3.2+, @functools.lru_cache).
-            old_key = self.queue.popleft()
-            del self[old_key]
-        return normalized
-
-
-_normalized_headers = _NormalizedHeaderCache(1000)
-
-
+from tornado.escape import native_str, parse_qs_bytes, utf8 
+from tornado.log import gen_log 
+from tornado.util import ObjectDict, PY3 
+ 
+if PY3: 
+    import http.cookies as Cookie 
+    from http.client import responses 
+    from urllib.parse import urlencode, urlparse, urlunparse, parse_qsl 
+else: 
+    import Cookie 
+    from httplib import responses 
+    from urllib import urlencode 
+    from urlparse import urlparse, urlunparse, parse_qsl 
+ 
+ 
+# responses is unused in this file, but we re-export it to other files. 
+# Reference it so pyflakes doesn't complain. 
+responses 
+ 
+try: 
+    from ssl import SSLError 
+except ImportError: 
+    # ssl is unavailable on app engine. 
+    class _SSLError(Exception): 
+        pass 
+    # Hack around a mypy limitation. We can't simply put "type: ignore" 
+    # on the class definition itself; must go through an assignment. 
+    SSLError = _SSLError  # type: ignore 
+ 
+try: 
+    import typing 
+except ImportError: 
+    pass 
+ 
+ 
+# RFC 7230 section 3.5: a recipient MAY recognize a single LF as a line 
+# terminator and ignore any preceding CR. 
+_CRLF_RE = re.compile(r'\r?\n') 
+ 
+ 
+class _NormalizedHeaderCache(dict): 
+    """Dynamic cached mapping of header names to Http-Header-Case. 
+ 
+    Implemented as a dict subclass so that cache hits are as fast as a 
+    normal dict lookup, without the overhead of a python function 
+    call. 
+ 
+    >>> normalized_headers = _NormalizedHeaderCache(10) 
+    >>> normalized_headers["coNtent-TYPE"] 
+    'Content-Type' 
+    """ 
+    def __init__(self, size): 
+        super(_NormalizedHeaderCache, self).__init__() 
+        self.size = size 
+        self.queue = collections.deque() 
+ 
+    def __missing__(self, key): 
+        normalized = "-".join([w.capitalize() for w in key.split("-")]) 
+        self[key] = normalized 
+        self.queue.append(key) 
+        if len(self.queue) > self.size: 
+            # Limit the size of the cache.  LRU would be better, but this 
+            # simpler approach should be fine.  In Python 2.7+ we could 
+            # use OrderedDict (or in 3.2+, @functools.lru_cache). 
+            old_key = self.queue.popleft() 
+            del self[old_key] 
+        return normalized 
+ 
+ 
+_normalized_headers = _NormalizedHeaderCache(1000) 
+ 
+ 
 class HTTPHeaders(MutableMapping):
-    """A dictionary that maintains ``Http-Header-Case`` for all keys.
-
-    Supports multiple values per key via a pair of new methods,
-    `add()` and `get_list()`.  The regular dictionary interface
-    returns a single value per key, with multiple values joined by a
-    comma.
-
-    >>> h = HTTPHeaders({"content-type": "text/html"})
-    >>> list(h.keys())
-    ['Content-Type']
-    >>> h["Content-Type"]
-    'text/html'
-
-    >>> h.add("Set-Cookie", "A=B")
-    >>> h.add("Set-Cookie", "C=D")
-    >>> h["set-cookie"]
-    'A=B,C=D'
-    >>> h.get_list("set-cookie")
-    ['A=B', 'C=D']
-
-    >>> for (k,v) in sorted(h.get_all()):
-    ...    print('%s: %s' % (k,v))
-    ...
-    Content-Type: text/html
-    Set-Cookie: A=B
-    Set-Cookie: C=D
-    """
-    def __init__(self, *args, **kwargs):
-        self._dict = {}  # type: typing.Dict[str, str]
-        self._as_list = {}  # type: typing.Dict[str, typing.List[str]]
-        self._last_key = None
-        if (len(args) == 1 and len(kwargs) == 0 and
-                isinstance(args[0], HTTPHeaders)):
-            # Copy constructor
-            for k, v in args[0].get_all():
-                self.add(k, v)
-        else:
-            # Dict-style initialization
-            self.update(*args, **kwargs)
-
-    # new public methods
-
-    def add(self, name, value):
-        # type: (str, str) -> None
-        """Adds a new value for the given key."""
-        norm_name = _normalized_headers[name]
-        self._last_key = norm_name
-        if norm_name in self:
-            self._dict[norm_name] = (native_str(self[norm_name]) + ',' +
-                                     native_str(value))
-            self._as_list[norm_name].append(value)
-        else:
-            self[norm_name] = value
-
-    def get_list(self, name):
-        """Returns all values for the given header as a list."""
-        norm_name = _normalized_headers[name]
-        return self._as_list.get(norm_name, [])
-
-    def get_all(self):
-        # type: () -> typing.Iterable[typing.Tuple[str, str]]
-        """Returns an iterable of all (name, value) pairs.
-
-        If a header has multiple values, multiple pairs will be
-        returned with the same name.
-        """
-        for name, values in self._as_list.items():
-            for value in values:
-                yield (name, value)
-
-    def parse_line(self, line):
-        """Updates the dictionary with a single header line.
-
-        >>> h = HTTPHeaders()
-        >>> h.parse_line("Content-Type: text/html")
-        >>> h.get('content-type')
-        'text/html'
-        """
-        if line[0].isspace():
-            # continuation of a multi-line header
-            new_part = ' ' + line.lstrip()
-            self._as_list[self._last_key][-1] += new_part
-            self._dict[self._last_key] += new_part
-        else:
-            name, value = line.split(":", 1)
-            self.add(name, value.strip())
-
-    @classmethod
-    def parse(cls, headers):
-        """Returns a dictionary from HTTP header text.
-
-        >>> h = HTTPHeaders.parse("Content-Type: text/html\\r\\nContent-Length: 42\\r\\n")
-        >>> sorted(h.items())
-        [('Content-Length', '42'), ('Content-Type', 'text/html')]
-        """
-        h = cls()
-        for line in _CRLF_RE.split(headers):
-            if line:
-                h.parse_line(line)
-        return h
-
-    # MutableMapping abstract method implementations.
-
-    def __setitem__(self, name, value):
-        norm_name = _normalized_headers[name]
-        self._dict[norm_name] = value
-        self._as_list[norm_name] = [value]
-
-    def __getitem__(self, name):
-        # type: (str) -> str
-        return self._dict[_normalized_headers[name]]
-
-    def __delitem__(self, name):
-        norm_name = _normalized_headers[name]
-        del self._dict[norm_name]
-        del self._as_list[norm_name]
-
-    def __len__(self):
-        return len(self._dict)
-
-    def __iter__(self):
-        return iter(self._dict)
-
-    def copy(self):
-        # defined in dict but not in MutableMapping.
-        return HTTPHeaders(self)
-
-    # Use our overridden copy method for the copy.copy module.
-    # This makes shallow copies one level deeper, but preserves
-    # the appearance that HTTPHeaders is a single container.
-    __copy__ = copy
-
-    def __str__(self):
-        lines = []
-        for name, value in self.get_all():
-            lines.append("%s: %s\n" % (name, value))
-        return "".join(lines)
-
-    __unicode__ = __str__
-
-
-class HTTPServerRequest(object):
-    """A single HTTP request.
-
-    All attributes are type `str` unless otherwise noted.
-
-    .. attribute:: method
-
-       HTTP request method, e.g. "GET" or "POST"
-
-    .. attribute:: uri
-
-       The requested uri.
-
-    .. attribute:: path
-
-       The path portion of `uri`
-
-    .. attribute:: query
-
-       The query portion of `uri`
-
-    .. attribute:: version
-
-       HTTP version specified in request, e.g. "HTTP/1.1"
-
-    .. attribute:: headers
-
-       `.HTTPHeaders` dictionary-like object for request headers.  Acts like
-       a case-insensitive dictionary with additional methods for repeated
-       headers.
-
-    .. attribute:: body
-
-       Request body, if present, as a byte string.
-
-    .. attribute:: remote_ip
-
-       Client's IP address as a string.  If ``HTTPServer.xheaders`` is set,
-       will pass along the real IP address provided by a load balancer
-       in the ``X-Real-Ip`` or ``X-Forwarded-For`` header.
-
-    .. versionchanged:: 3.1
-       The list format of ``X-Forwarded-For`` is now supported.
-
-    .. attribute:: protocol
-
-       The protocol used, either "http" or "https".  If ``HTTPServer.xheaders``
-       is set, will pass along the protocol used by a load balancer if
-       reported via an ``X-Scheme`` header.
-
-    .. attribute:: host
-
-       The requested hostname, usually taken from the ``Host`` header.
-
-    .. attribute:: arguments
-
-       GET/POST arguments are available in the arguments property, which
-       maps arguments names to lists of values (to support multiple values
-       for individual names). Names are of type `str`, while arguments
-       are byte strings.  Note that this is different from
-       `.RequestHandler.get_argument`, which returns argument values as
-       unicode strings.
-
-    .. attribute:: query_arguments
-
-       Same format as ``arguments``, but contains only arguments extracted
-       from the query string.
-
-       .. versionadded:: 3.2
-
-    .. attribute:: body_arguments
-
-       Same format as ``arguments``, but contains only arguments extracted
-       from the request body.
-
-       .. versionadded:: 3.2
-
-    .. attribute:: files
-
-       File uploads are available in the files property, which maps file
-       names to lists of `.HTTPFile`.
-
-    .. attribute:: connection
-
-       An HTTP request is attached to a single HTTP connection, which can
-       be accessed through the "connection" attribute. Since connections
-       are typically kept open in HTTP/1.1, multiple requests can be handled
-       sequentially on a single connection.
-
-    .. versionchanged:: 4.0
-       Moved from ``tornado.httpserver.HTTPRequest``.
-    """
-    def __init__(self, method=None, uri=None, version="HTTP/1.0", headers=None,
-                 body=None, host=None, files=None, connection=None,
-                 start_line=None, server_connection=None):
-        if start_line is not None:
-            method, uri, version = start_line
-        self.method = method
-        self.uri = uri
-        self.version = version
-        self.headers = headers or HTTPHeaders()
-        self.body = body or b""
-
-        # set remote IP and protocol
-        context = getattr(connection, 'context', None)
-        self.remote_ip = getattr(context, 'remote_ip', None)
-        self.protocol = getattr(context, 'protocol', "http")
-
-        self.host = host or self.headers.get("Host") or "127.0.0.1"
-        self.host_name = split_host_and_port(self.host.lower())[0]
-        self.files = files or {}
-        self.connection = connection
-        self.server_connection = server_connection
-        self._start_time = time.time()
-        self._finish_time = None
-
-        self.path, sep, self.query = uri.partition('?')
-        self.arguments = parse_qs_bytes(self.query, keep_blank_values=True)
-        self.query_arguments = copy.deepcopy(self.arguments)
-        self.body_arguments = {}
-
-    def supports_http_1_1(self):
-        """Returns True if this request supports HTTP/1.1 semantics.
-
-        .. deprecated:: 4.0
-           Applications are less likely to need this information with the
-           introduction of `.HTTPConnection`.  If you still need it, access
-           the ``version`` attribute directly.
-        """
-        return self.version == "HTTP/1.1"
-
-    @property
-    def cookies(self):
-        """A dictionary of Cookie.Morsel objects."""
-        if not hasattr(self, "_cookies"):
-            self._cookies = Cookie.SimpleCookie()
-            if "Cookie" in self.headers:
-                try:
-                    parsed = parse_cookie(self.headers["Cookie"])
-                except Exception:
-                    pass
-                else:
-                    for k, v in parsed.items():
-                        try:
-                            self._cookies[k] = v
-                        except Exception:
-                            # SimpleCookie imposes some restrictions on keys;
-                            # parse_cookie does not. Discard any cookies
-                            # with disallowed keys.
-                            pass
-        return self._cookies
-
-    def write(self, chunk, callback=None):
-        """Writes the given chunk to the response stream.
-
-        .. deprecated:: 4.0
-           Use ``request.connection`` and the `.HTTPConnection` methods
-           to write the response.
-        """
-        assert isinstance(chunk, bytes)
-        assert self.version.startswith("HTTP/1."), \
-            "deprecated interface only supported in HTTP/1.x"
-        self.connection.write(chunk, callback=callback)
-
-    def finish(self):
-        """Finishes this HTTP request on the open connection.
-
-        .. deprecated:: 4.0
-           Use ``request.connection`` and the `.HTTPConnection` methods
-           to write the response.
-        """
-        self.connection.finish()
-        self._finish_time = time.time()
-
-    def full_url(self):
-        """Reconstructs the full URL for this request."""
-        return self.protocol + "://" + self.host + self.uri
-
-    def request_time(self):
-        """Returns the amount of time it took for this request to execute."""
-        if self._finish_time is None:
-            return time.time() - self._start_time
-        else:
-            return self._finish_time - self._start_time
-
-    def get_ssl_certificate(self, binary_form=False):
-        """Returns the client's SSL certificate, if any.
-
-        To use client certificates, the HTTPServer's
-        `ssl.SSLContext.verify_mode` field must be set, e.g.::
-
-            ssl_ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
-            ssl_ctx.load_cert_chain("foo.crt", "foo.key")
-            ssl_ctx.load_verify_locations("cacerts.pem")
-            ssl_ctx.verify_mode = ssl.CERT_REQUIRED
-            server = HTTPServer(app, ssl_options=ssl_ctx)
-
-        By default, the return value is a dictionary (or None, if no
-        client certificate is present).  If ``binary_form`` is true, a
-        DER-encoded form of the certificate is returned instead.  See
-        SSLSocket.getpeercert() in the standard library for more
-        details.
-        http://docs.python.org/library/ssl.html#sslsocket-objects
-        """
-        try:
-            return self.connection.stream.socket.getpeercert(
-                binary_form=binary_form)
-        except SSLError:
-            return None
-
-    def _parse_body(self):
-        parse_body_arguments(
-            self.headers.get("Content-Type", ""), self.body,
-            self.body_arguments, self.files,
-            self.headers)
-
-        for k, v in self.body_arguments.items():
-            self.arguments.setdefault(k, []).extend(v)
-
-    def __repr__(self):
-        attrs = ("protocol", "host", "method", "uri", "version", "remote_ip")
-        args = ", ".join(["%s=%r" % (n, getattr(self, n)) for n in attrs])
-        return "%s(%s, headers=%s)" % (
-            self.__class__.__name__, args, dict(self.headers))
-
-
-class HTTPInputError(Exception):
-    """Exception class for malformed HTTP requests or responses
-    from remote sources.
-
-    .. versionadded:: 4.0
-    """
-    pass
-
-
-class HTTPOutputError(Exception):
-    """Exception class for errors in HTTP output.
-
-    .. versionadded:: 4.0
-    """
-    pass
-
-
-class HTTPServerConnectionDelegate(object):
-    """Implement this interface to handle requests from `.HTTPServer`.
-
-    .. versionadded:: 4.0
-    """
-    def start_request(self, server_conn, request_conn):
-        """This method is called by the server when a new request has started.
-
-        :arg server_conn: is an opaque object representing the long-lived
-            (e.g. tcp-level) connection.
-        :arg request_conn: is a `.HTTPConnection` object for a single
-            request/response exchange.
-
-        This method should return a `.HTTPMessageDelegate`.
-        """
-        raise NotImplementedError()
-
-    def on_close(self, server_conn):
-        """This method is called when a connection has been closed.
-
-        :arg server_conn: is a server connection that has previously been
-            passed to ``start_request``.
-        """
-        pass
-
-
-class HTTPMessageDelegate(object):
-    """Implement this interface to handle an HTTP request or response.
-
-    .. versionadded:: 4.0
-    """
-    def headers_received(self, start_line, headers):
-        """Called when the HTTP headers have been received and parsed.
-
-        :arg start_line: a `.RequestStartLine` or `.ResponseStartLine`
-            depending on whether this is a client or server message.
-        :arg headers: a `.HTTPHeaders` instance.
-
-        Some `.HTTPConnection` methods can only be called during
-        ``headers_received``.
-
-        May return a `.Future`; if it does the body will not be read
-        until it is done.
-        """
-        pass
-
-    def data_received(self, chunk):
-        """Called when a chunk of data has been received.
-
-        May return a `.Future` for flow control.
-        """
-        pass
-
-    def finish(self):
-        """Called after the last chunk of data has been received."""
-        pass
-
-    def on_connection_close(self):
-        """Called if the connection is closed without finishing the request.
-
-        If ``headers_received`` is called, either ``finish`` or
-        ``on_connection_close`` will be called, but not both.
-        """
-        pass
-
-
-class HTTPConnection(object):
-    """Applications use this interface to write their responses.
-
-    .. versionadded:: 4.0
-    """
-    def write_headers(self, start_line, headers, chunk=None, callback=None):
-        """Write an HTTP header block.
-
-        :arg start_line: a `.RequestStartLine` or `.ResponseStartLine`.
-        :arg headers: a `.HTTPHeaders` instance.
-        :arg chunk: the first (optional) chunk of data.  This is an optimization
-            so that small responses can be written in the same call as their
-            headers.
-        :arg callback: a callback to be run when the write is complete.
-
-        The ``version`` field of ``start_line`` is ignored.
-
-        Returns a `.Future` if no callback is given.
-        """
-        raise NotImplementedError()
-
-    def write(self, chunk, callback=None):
-        """Writes a chunk of body data.
-
-        The callback will be run when the write is complete.  If no callback
-        is given, returns a Future.
-        """
-        raise NotImplementedError()
-
-    def finish(self):
-        """Indicates that the last body data has been written.
-        """
-        raise NotImplementedError()
-
-
-def url_concat(url, args):
-    """Concatenate url and arguments regardless of whether
-    url has existing query parameters.
-
-    ``args`` may be either a dictionary or a list of key-value pairs
-    (the latter allows for multiple values with the same key.
-
-    >>> url_concat("http://example.com/foo", dict(c="d"))
-    'http://example.com/foo?c=d'
-    >>> url_concat("http://example.com/foo?a=b", dict(c="d"))
-    'http://example.com/foo?a=b&c=d'
-    >>> url_concat("http://example.com/foo?a=b", [("c", "d"), ("c", "d2")])
-    'http://example.com/foo?a=b&c=d&c=d2'
-    """
-    if args is None:
-        return url
-    parsed_url = urlparse(url)
-    if isinstance(args, dict):
-        parsed_query = parse_qsl(parsed_url.query, keep_blank_values=True)
-        parsed_query.extend(args.items())
-    elif isinstance(args, list) or isinstance(args, tuple):
-        parsed_query = parse_qsl(parsed_url.query, keep_blank_values=True)
-        parsed_query.extend(args)
-    else:
-        err = "'args' parameter should be dict, list or tuple. Not {0}".format(
-            type(args))
-        raise TypeError(err)
-    final_query = urlencode(parsed_query)
-    url = urlunparse((
-        parsed_url[0],
-        parsed_url[1],
-        parsed_url[2],
-        parsed_url[3],
-        final_query,
-        parsed_url[5]))
-    return url
-
-
-class HTTPFile(ObjectDict):
-    """Represents a file uploaded via a form.
-
-    For backwards compatibility, its instance attributes are also
-    accessible as dictionary keys.
-
-    * ``filename``
-    * ``body``
-    * ``content_type``
-    """
-    pass
-
-
-def _parse_request_range(range_header):
-    """Parses a Range header.
-
-    Returns either ``None`` or tuple ``(start, end)``.
-    Note that while the HTTP headers use inclusive byte positions,
-    this method returns indexes suitable for use in slices.
-
-    >>> start, end = _parse_request_range("bytes=1-2")
-    >>> start, end
-    (1, 3)
-    >>> [0, 1, 2, 3, 4][start:end]
-    [1, 2]
-    >>> _parse_request_range("bytes=6-")
-    (6, None)
-    >>> _parse_request_range("bytes=-6")
-    (-6, None)
-    >>> _parse_request_range("bytes=-0")
-    (None, 0)
-    >>> _parse_request_range("bytes=")
-    (None, None)
-    >>> _parse_request_range("foo=42")
-    >>> _parse_request_range("bytes=1-2,6-10")
-
-    Note: only supports one range (ex, ``bytes=1-2,6-10`` is not allowed).
-
-    See [0] for the details of the range header.
-
-    [0]: http://greenbytes.de/tech/webdav/draft-ietf-httpbis-p5-range-latest.html#byte.ranges
-    """
-    unit, _, value = range_header.partition("=")
-    unit, value = unit.strip(), value.strip()
-    if unit != "bytes":
-        return None
-    start_b, _, end_b = value.partition("-")
-    try:
-        start = _int_or_none(start_b)
-        end = _int_or_none(end_b)
-    except ValueError:
-        return None
-    if end is not None:
-        if start is None:
-            if end != 0:
-                start = -end
-                end = None
-        else:
-            end += 1
-    return (start, end)
-
-
-def _get_content_range(start, end, total):
-    """Returns a suitable Content-Range header:
-
-    >>> print(_get_content_range(None, 1, 4))
-    bytes 0-0/4
-    >>> print(_get_content_range(1, 3, 4))
-    bytes 1-2/4
-    >>> print(_get_content_range(None, None, 4))
-    bytes 0-3/4
-    """
-    start = start or 0
-    end = (end or total) - 1
-    return "bytes %s-%s/%s" % (start, end, total)
-
-
-def _int_or_none(val):
-    val = val.strip()
-    if val == "":
-        return None
-    return int(val)
-
-
-def parse_body_arguments(content_type, body, arguments, files, headers=None):
-    """Parses a form request body.
-
-    Supports ``application/x-www-form-urlencoded`` and
-    ``multipart/form-data``.  The ``content_type`` parameter should be
-    a string and ``body`` should be a byte string.  The ``arguments``
-    and ``files`` parameters are dictionaries that will be updated
-    with the parsed contents.
-    """
-    if headers and 'Content-Encoding' in headers:
-        gen_log.warning("Unsupported Content-Encoding: %s",
-                        headers['Content-Encoding'])
-        return
-    if content_type.startswith("application/x-www-form-urlencoded"):
-        try:
-            uri_arguments = parse_qs_bytes(native_str(body), keep_blank_values=True)
-        except Exception as e:
-            gen_log.warning('Invalid x-www-form-urlencoded body: %s', e)
-            uri_arguments = {}
-        for name, values in uri_arguments.items():
-            if values:
-                arguments.setdefault(name, []).extend(values)
-    elif content_type.startswith("multipart/form-data"):
-        try:
-            fields = content_type.split(";")
-            for field in fields:
-                k, sep, v = field.strip().partition("=")
-                if k == "boundary" and v:
-                    parse_multipart_form_data(utf8(v), body, arguments, files)
-                    break
-            else:
-                raise ValueError("multipart boundary not found")
-        except Exception as e:
-            gen_log.warning("Invalid multipart/form-data: %s", e)
-
-
-def parse_multipart_form_data(boundary, data, arguments, files):
-    """Parses a ``multipart/form-data`` body.
-
-    The ``boundary`` and ``data`` parameters are both byte strings.
-    The dictionaries given in the arguments and files parameters
-    will be updated with the contents of the body.
-    """
-    # The standard allows for the boundary to be quoted in the header,
-    # although it's rare (it happens at least for google app engine
-    # xmpp).  I think we're also supposed to handle backslash-escapes
-    # here but I'll save that until we see a client that uses them
-    # in the wild.
-    if boundary.startswith(b'"') and boundary.endswith(b'"'):
-        boundary = boundary[1:-1]
-    final_boundary_index = data.rfind(b"--" + boundary + b"--")
-    if final_boundary_index == -1:
-        gen_log.warning("Invalid multipart/form-data: no final boundary")
-        return
-    parts = data[:final_boundary_index].split(b"--" + boundary + b"\r\n")
-    for part in parts:
-        if not part:
-            continue
-        eoh = part.find(b"\r\n\r\n")
-        if eoh == -1:
-            gen_log.warning("multipart/form-data missing headers")
-            continue
-        headers = HTTPHeaders.parse(part[:eoh].decode("utf-8"))
-        disp_header = headers.get("Content-Disposition", "")
-        disposition, disp_params = _parse_header(disp_header)
-        if disposition != "form-data" or not part.endswith(b"\r\n"):
-            gen_log.warning("Invalid multipart/form-data")
-            continue
-        value = part[eoh + 4:-2]
-        if not disp_params.get("name"):
-            gen_log.warning("multipart/form-data value missing name")
-            continue
-        name = disp_params["name"]
-        if disp_params.get("filename"):
-            ctype = headers.get("Content-Type", "application/unknown")
-            files.setdefault(name, []).append(HTTPFile(  # type: ignore
-                filename=disp_params["filename"], body=value,
-                content_type=ctype))
-        else:
-            arguments.setdefault(name, []).append(value)
-
-
-def format_timestamp(ts):
-    """Formats a timestamp in the format used by HTTP.
-
-    The argument may be a numeric timestamp as returned by `time.time`,
-    a time tuple as returned by `time.gmtime`, or a `datetime.datetime`
-    object.
-
-    >>> format_timestamp(1359312200)
-    'Sun, 27 Jan 2013 18:43:20 GMT'
-    """
-    if isinstance(ts, numbers.Real):
-        pass
-    elif isinstance(ts, (tuple, time.struct_time)):
-        ts = calendar.timegm(ts)
-    elif isinstance(ts, datetime.datetime):
-        ts = calendar.timegm(ts.utctimetuple())
-    else:
-        raise TypeError("unknown timestamp type: %r" % ts)
-    return email.utils.formatdate(ts, usegmt=True)
-
-
-RequestStartLine = collections.namedtuple(
-    'RequestStartLine', ['method', 'path', 'version'])
-
-
-def parse_request_start_line(line):
-    """Returns a (method, path, version) tuple for an HTTP 1.x request line.
-
-    The response is a `collections.namedtuple`.
-
-    >>> parse_request_start_line("GET /foo HTTP/1.1")
-    RequestStartLine(method='GET', path='/foo', version='HTTP/1.1')
-    """
-    try:
-        method, path, version = line.split(" ")
-    except ValueError:
-        raise HTTPInputError("Malformed HTTP request line")
-    if not re.match(r"^HTTP/1\.[0-9]$", version):
-        raise HTTPInputError(
-            "Malformed HTTP version in HTTP Request-Line: %r" % version)
-    return RequestStartLine(method, path, version)
-
-
-ResponseStartLine = collections.namedtuple(
-    'ResponseStartLine', ['version', 'code', 'reason'])
-
-
-def parse_response_start_line(line):
-    """Returns a (version, code, reason) tuple for an HTTP 1.x response line.
-
-    The response is a `collections.namedtuple`.
-
-    >>> parse_response_start_line("HTTP/1.1 200 OK")
-    ResponseStartLine(version='HTTP/1.1', code=200, reason='OK')
-    """
-    line = native_str(line)
-    match = re.match("(HTTP/1.[0-9]) ([0-9]+) ([^\r]*)", line)
-    if not match:
-        raise HTTPInputError("Error parsing response start line")
-    return ResponseStartLine(match.group(1), int(match.group(2)),
-                             match.group(3))
-
-# _parseparam and _parse_header are copied and modified from python2.7's cgi.py
-# The original 2.7 version of this code did not correctly support some
-# combinations of semicolons and double quotes.
-# It has also been modified to support valueless parameters as seen in
-# websocket extension negotiations.
-
-
-def _parseparam(s):
-    while s[:1] == ';':
-        s = s[1:]
-        end = s.find(';')
-        while end > 0 and (s.count('"', 0, end) - s.count('\\"', 0, end)) % 2:
-            end = s.find(';', end + 1)
-        if end < 0:
-            end = len(s)
-        f = s[:end]
-        yield f.strip()
-        s = s[end:]
-
-
-def _parse_header(line):
-    """Parse a Content-type like header.
-
-    Return the main content-type and a dictionary of options.
-
-    """
-    parts = _parseparam(';' + line)
-    key = next(parts)
-    pdict = {}
-    for p in parts:
-        i = p.find('=')
-        if i >= 0:
-            name = p[:i].strip().lower()
-            value = p[i + 1:].strip()
-            if len(value) >= 2 and value[0] == value[-1] == '"':
-                value = value[1:-1]
-                value = value.replace('\\\\', '\\').replace('\\"', '"')
-            pdict[name] = value
-        else:
-            pdict[p] = None
-    return key, pdict
-
-
-def _encode_header(key, pdict):
-    """Inverse of _parse_header.
-
-    >>> _encode_header('permessage-deflate',
-    ...     {'client_max_window_bits': 15, 'client_no_context_takeover': None})
-    'permessage-deflate; client_max_window_bits=15; client_no_context_takeover'
-    """
-    if not pdict:
-        return key
-    out = [key]
-    # Sort the parameters just to make it easy to test.
-    for k, v in sorted(pdict.items()):
-        if v is None:
-            out.append(k)
-        else:
-            # TODO: quote if necessary.
-            out.append('%s=%s' % (k, v))
-    return '; '.join(out)
-
-
-def doctests():
-    import doctest
-    return doctest.DocTestSuite()
-
-
-def split_host_and_port(netloc):
-    """Returns ``(host, port)`` tuple from ``netloc``.
-
-    Returned ``port`` will be ``None`` if not present.
-
-    .. versionadded:: 4.1
-    """
-    match = re.match(r'^(.+):(\d+)$', netloc)
-    if match:
-        host = match.group(1)
-        port = int(match.group(2))
-    else:
-        host = netloc
-        port = None
-    return (host, port)
-
-
-_OctalPatt = re.compile(r"\\[0-3][0-7][0-7]")
-_QuotePatt = re.compile(r"[\\].")
-_nulljoin = ''.join
-
-
-def _unquote_cookie(str):
-    """Handle double quotes and escaping in cookie values.
-
-    This method is copied verbatim from the Python 3.5 standard
-    library (http.cookies._unquote) so we don't have to depend on
-    non-public interfaces.
-    """
-    # If there aren't any doublequotes,
-    # then there can't be any special characters.  See RFC 2109.
-    if str is None or len(str) < 2:
-        return str
-    if str[0] != '"' or str[-1] != '"':
-        return str
-
-    # We have to assume that we must decode this string.
-    # Down to work.
-
-    # Remove the "s
-    str = str[1:-1]
-
-    # Check for special sequences.  Examples:
-    #    \012 --> \n
-    #    \"   --> "
-    #
-    i = 0
-    n = len(str)
-    res = []
-    while 0 <= i < n:
-        o_match = _OctalPatt.search(str, i)
-        q_match = _QuotePatt.search(str, i)
-        if not o_match and not q_match:              # Neither matched
-            res.append(str[i:])
-            break
-        # else:
-        j = k = -1
-        if o_match:
-            j = o_match.start(0)
-        if q_match:
-            k = q_match.start(0)
-        if q_match and (not o_match or k < j):     # QuotePatt matched
-            res.append(str[i:k])
-            res.append(str[k + 1])
-            i = k + 2
-        else:                                      # OctalPatt matched
-            res.append(str[i:j])
-            res.append(chr(int(str[j + 1:j + 4], 8)))
-            i = j + 4
-    return _nulljoin(res)
-
-
-def parse_cookie(cookie):
-    """Parse a ``Cookie`` HTTP header into a dict of name/value pairs.
-
-    This function attempts to mimic browser cookie parsing behavior;
-    it specifically does not follow any of the cookie-related RFCs
-    (because browsers don't either).
-
-    The algorithm used is identical to that used by Django version 1.9.10.
-
-    .. versionadded:: 4.4.2
-    """
-    cookiedict = {}
-    for chunk in cookie.split(str(';')):
-        if str('=') in chunk:
-            key, val = chunk.split(str('='), 1)
-        else:
-            # Assume an empty name per
-            # https://bugzilla.mozilla.org/show_bug.cgi?id=169091
-            key, val = str(''), chunk
-        key, val = key.strip(), val.strip()
-        if key or val:
-            # unquote using Python's algorithm.
-            cookiedict[key] = _unquote_cookie(val)
-    return cookiedict
+    """A dictionary that maintains ``Http-Header-Case`` for all keys. 
+ 
+    Supports multiple values per key via a pair of new methods, 
+    `add()` and `get_list()`.  The regular dictionary interface 
+    returns a single value per key, with multiple values joined by a 
+    comma. 
+ 
+    >>> h = HTTPHeaders({"content-type": "text/html"}) 
+    >>> list(h.keys()) 
+    ['Content-Type'] 
+    >>> h["Content-Type"] 
+    'text/html' 
+ 
+    >>> h.add("Set-Cookie", "A=B") 
+    >>> h.add("Set-Cookie", "C=D") 
+    >>> h["set-cookie"] 
+    'A=B,C=D' 
+    >>> h.get_list("set-cookie") 
+    ['A=B', 'C=D'] 
+ 
+    >>> for (k,v) in sorted(h.get_all()): 
+    ...    print('%s: %s' % (k,v)) 
+    ... 
+    Content-Type: text/html 
+    Set-Cookie: A=B 
+    Set-Cookie: C=D 
+    """ 
+    def __init__(self, *args, **kwargs): 
+        self._dict = {}  # type: typing.Dict[str, str] 
+        self._as_list = {}  # type: typing.Dict[str, typing.List[str]] 
+        self._last_key = None 
+        if (len(args) == 1 and len(kwargs) == 0 and 
+                isinstance(args[0], HTTPHeaders)): 
+            # Copy constructor 
+            for k, v in args[0].get_all(): 
+                self.add(k, v) 
+        else: 
+            # Dict-style initialization 
+            self.update(*args, **kwargs) 
+ 
+    # new public methods 
+ 
+    def add(self, name, value): 
+        # type: (str, str) -> None 
+        """Adds a new value for the given key.""" 
+        norm_name = _normalized_headers[name] 
+        self._last_key = norm_name 
+        if norm_name in self: 
+            self._dict[norm_name] = (native_str(self[norm_name]) + ',' + 
+                                     native_str(value)) 
+            self._as_list[norm_name].append(value) 
+        else: 
+            self[norm_name] = value 
+ 
+    def get_list(self, name): 
+        """Returns all values for the given header as a list.""" 
+        norm_name = _normalized_headers[name] 
+        return self._as_list.get(norm_name, []) 
+ 
+    def get_all(self): 
+        # type: () -> typing.Iterable[typing.Tuple[str, str]] 
+        """Returns an iterable of all (name, value) pairs. 
+ 
+        If a header has multiple values, multiple pairs will be 
+        returned with the same name. 
+        """ 
+        for name, values in self._as_list.items(): 
+            for value in values: 
+                yield (name, value) 
+ 
+    def parse_line(self, line): 
+        """Updates the dictionary with a single header line. 
+ 
+        >>> h = HTTPHeaders() 
+        >>> h.parse_line("Content-Type: text/html") 
+        >>> h.get('content-type') 
+        'text/html' 
+        """ 
+        if line[0].isspace(): 
+            # continuation of a multi-line header 
+            new_part = ' ' + line.lstrip() 
+            self._as_list[self._last_key][-1] += new_part 
+            self._dict[self._last_key] += new_part 
+        else: 
+            name, value = line.split(":", 1) 
+            self.add(name, value.strip()) 
+ 
+    @classmethod 
+    def parse(cls, headers): 
+        """Returns a dictionary from HTTP header text. 
+ 
+        >>> h = HTTPHeaders.parse("Content-Type: text/html\\r\\nContent-Length: 42\\r\\n") 
+        >>> sorted(h.items()) 
+        [('Content-Length', '42'), ('Content-Type', 'text/html')] 
+        """ 
+        h = cls() 
+        for line in _CRLF_RE.split(headers): 
+            if line: 
+                h.parse_line(line) 
+        return h 
+ 
+    # MutableMapping abstract method implementations. 
+ 
+    def __setitem__(self, name, value): 
+        norm_name = _normalized_headers[name] 
+        self._dict[norm_name] = value 
+        self._as_list[norm_name] = [value] 
+ 
+    def __getitem__(self, name): 
+        # type: (str) -> str 
+        return self._dict[_normalized_headers[name]] 
+ 
+    def __delitem__(self, name): 
+        norm_name = _normalized_headers[name] 
+        del self._dict[norm_name] 
+        del self._as_list[norm_name] 
+ 
+    def __len__(self): 
+        return len(self._dict) 
+ 
+    def __iter__(self): 
+        return iter(self._dict) 
+ 
+    def copy(self): 
+        # defined in dict but not in MutableMapping. 
+        return HTTPHeaders(self) 
+ 
+    # Use our overridden copy method for the copy.copy module. 
+    # This makes shallow copies one level deeper, but preserves 
+    # the appearance that HTTPHeaders is a single container. 
+    __copy__ = copy 
+ 
+    def __str__(self): 
+        lines = [] 
+        for name, value in self.get_all(): 
+            lines.append("%s: %s\n" % (name, value)) 
+        return "".join(lines) 
+ 
+    __unicode__ = __str__ 
+ 
+ 
+class HTTPServerRequest(object): 
+    """A single HTTP request. 
+ 
+    All attributes are type `str` unless otherwise noted. 
+ 
+    .. attribute:: method 
+ 
+       HTTP request method, e.g. "GET" or "POST" 
+ 
+    .. attribute:: uri 
+ 
+       The requested uri. 
+ 
+    .. attribute:: path 
+ 
+       The path portion of `uri` 
+ 
+    .. attribute:: query 
+ 
+       The query portion of `uri` 
+ 
+    .. attribute:: version 
+ 
+       HTTP version specified in request, e.g. "HTTP/1.1" 
+ 
+    .. attribute:: headers 
+ 
+       `.HTTPHeaders` dictionary-like object for request headers.  Acts like 
+       a case-insensitive dictionary with additional methods for repeated 
+       headers. 
+ 
+    .. attribute:: body 
+ 
+       Request body, if present, as a byte string. 
+ 
+    .. attribute:: remote_ip 
+ 
+       Client's IP address as a string.  If ``HTTPServer.xheaders`` is set, 
+       will pass along the real IP address provided by a load balancer 
+       in the ``X-Real-Ip`` or ``X-Forwarded-For`` header. 
+ 
+    .. versionchanged:: 3.1 
+       The list format of ``X-Forwarded-For`` is now supported. 
+ 
+    .. attribute:: protocol 
+ 
+       The protocol used, either "http" or "https".  If ``HTTPServer.xheaders`` 
+       is set, will pass along the protocol used by a load balancer if 
+       reported via an ``X-Scheme`` header. 
+ 
+    .. attribute:: host 
+ 
+       The requested hostname, usually taken from the ``Host`` header. 
+ 
+    .. attribute:: arguments 
+ 
+       GET/POST arguments are available in the arguments property, which 
+       maps arguments names to lists of values (to support multiple values 
+       for individual names). Names are of type `str`, while arguments 
+       are byte strings.  Note that this is different from 
+       `.RequestHandler.get_argument`, which returns argument values as 
+       unicode strings. 
+ 
+    .. attribute:: query_arguments 
+ 
+       Same format as ``arguments``, but contains only arguments extracted 
+       from the query string. 
+ 
+       .. versionadded:: 3.2 
+ 
+    .. attribute:: body_arguments 
+ 
+       Same format as ``arguments``, but contains only arguments extracted 
+       from the request body. 
+ 
+       .. versionadded:: 3.2 
+ 
+    .. attribute:: files 
+ 
+       File uploads are available in the files property, which maps file 
+       names to lists of `.HTTPFile`. 
+ 
+    .. attribute:: connection 
+ 
+       An HTTP request is attached to a single HTTP connection, which can 
+       be accessed through the "connection" attribute. Since connections 
+       are typically kept open in HTTP/1.1, multiple requests can be handled 
+       sequentially on a single connection. 
+ 
+    .. versionchanged:: 4.0 
+       Moved from ``tornado.httpserver.HTTPRequest``. 
+    """ 
+    def __init__(self, method=None, uri=None, version="HTTP/1.0", headers=None, 
+                 body=None, host=None, files=None, connection=None, 
+                 start_line=None, server_connection=None): 
+        if start_line is not None: 
+            method, uri, version = start_line 
+        self.method = method 
+        self.uri = uri 
+        self.version = version 
+        self.headers = headers or HTTPHeaders() 
+        self.body = body or b"" 
+ 
+        # set remote IP and protocol 
+        context = getattr(connection, 'context', None) 
+        self.remote_ip = getattr(context, 'remote_ip', None) 
+        self.protocol = getattr(context, 'protocol', "http") 
+ 
+        self.host = host or self.headers.get("Host") or "127.0.0.1" 
+        self.host_name = split_host_and_port(self.host.lower())[0] 
+        self.files = files or {} 
+        self.connection = connection 
+        self.server_connection = server_connection 
+        self._start_time = time.time() 
+        self._finish_time = None 
+ 
+        self.path, sep, self.query = uri.partition('?') 
+        self.arguments = parse_qs_bytes(self.query, keep_blank_values=True) 
+        self.query_arguments = copy.deepcopy(self.arguments) 
+        self.body_arguments = {} 
+ 
+    def supports_http_1_1(self): 
+        """Returns True if this request supports HTTP/1.1 semantics. 
+ 
+        .. deprecated:: 4.0 
+           Applications are less likely to need this information with the 
+           introduction of `.HTTPConnection`.  If you still need it, access 
+           the ``version`` attribute directly. 
+        """ 
+        return self.version == "HTTP/1.1" 
+ 
+    @property 
+    def cookies(self): 
+        """A dictionary of Cookie.Morsel objects.""" 
+        if not hasattr(self, "_cookies"): 
+            self._cookies = Cookie.SimpleCookie() 
+            if "Cookie" in self.headers: 
+                try: 
+                    parsed = parse_cookie(self.headers["Cookie"]) 
+                except Exception: 
+                    pass 
+                else: 
+                    for k, v in parsed.items(): 
+                        try: 
+                            self._cookies[k] = v 
+                        except Exception: 
+                            # SimpleCookie imposes some restrictions on keys; 
+                            # parse_cookie does not. Discard any cookies 
+                            # with disallowed keys. 
+                            pass 
+        return self._cookies 
+ 
+    def write(self, chunk, callback=None): 
+        """Writes the given chunk to the response stream. 
+ 
+        .. deprecated:: 4.0 
+           Use ``request.connection`` and the `.HTTPConnection` methods 
+           to write the response. 
+        """ 
+        assert isinstance(chunk, bytes) 
+        assert self.version.startswith("HTTP/1."), \ 
+            "deprecated interface only supported in HTTP/1.x" 
+        self.connection.write(chunk, callback=callback) 
+ 
+    def finish(self): 
+        """Finishes this HTTP request on the open connection. 
+ 
+        .. deprecated:: 4.0 
+           Use ``request.connection`` and the `.HTTPConnection` methods 
+           to write the response. 
+        """ 
+        self.connection.finish() 
+        self._finish_time = time.time() 
+ 
+    def full_url(self): 
+        """Reconstructs the full URL for this request.""" 
+        return self.protocol + "://" + self.host + self.uri 
+ 
+    def request_time(self): 
+        """Returns the amount of time it took for this request to execute.""" 
+        if self._finish_time is None: 
+            return time.time() - self._start_time 
+        else: 
+            return self._finish_time - self._start_time 
+ 
+    def get_ssl_certificate(self, binary_form=False): 
+        """Returns the client's SSL certificate, if any. 
+ 
+        To use client certificates, the HTTPServer's 
+        `ssl.SSLContext.verify_mode` field must be set, e.g.:: 
+ 
+            ssl_ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH) 
+            ssl_ctx.load_cert_chain("foo.crt", "foo.key") 
+            ssl_ctx.load_verify_locations("cacerts.pem") 
+            ssl_ctx.verify_mode = ssl.CERT_REQUIRED 
+            server = HTTPServer(app, ssl_options=ssl_ctx) 
+ 
+        By default, the return value is a dictionary (or None, if no 
+        client certificate is present).  If ``binary_form`` is true, a 
+        DER-encoded form of the certificate is returned instead.  See 
+        SSLSocket.getpeercert() in the standard library for more 
+        details. 
+        http://docs.python.org/library/ssl.html#sslsocket-objects 
+        """ 
+        try: 
+            return self.connection.stream.socket.getpeercert( 
+                binary_form=binary_form) 
+        except SSLError: 
+            return None 
+ 
+    def _parse_body(self): 
+        parse_body_arguments( 
+            self.headers.get("Content-Type", ""), self.body, 
+            self.body_arguments, self.files, 
+            self.headers) 
+ 
+        for k, v in self.body_arguments.items(): 
+            self.arguments.setdefault(k, []).extend(v) 
+ 
+    def __repr__(self): 
+        attrs = ("protocol", "host", "method", "uri", "version", "remote_ip") 
+        args = ", ".join(["%s=%r" % (n, getattr(self, n)) for n in attrs]) 
+        return "%s(%s, headers=%s)" % ( 
+            self.__class__.__name__, args, dict(self.headers)) 
+ 
+ 
+class HTTPInputError(Exception): 
+    """Exception class for malformed HTTP requests or responses 
+    from remote sources. 
+ 
+    .. versionadded:: 4.0 
+    """ 
+    pass 
+ 
+ 
+class HTTPOutputError(Exception): 
+    """Exception class for errors in HTTP output. 
+ 
+    .. versionadded:: 4.0 
+    """ 
+    pass 
+ 
+ 
+class HTTPServerConnectionDelegate(object): 
+    """Implement this interface to handle requests from `.HTTPServer`. 
+ 
+    .. versionadded:: 4.0 
+    """ 
+    def start_request(self, server_conn, request_conn): 
+        """This method is called by the server when a new request has started. 
+ 
+        :arg server_conn: is an opaque object representing the long-lived 
+            (e.g. tcp-level) connection. 
+        :arg request_conn: is a `.HTTPConnection` object for a single 
+            request/response exchange. 
+ 
+        This method should return a `.HTTPMessageDelegate`. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def on_close(self, server_conn): 
+        """This method is called when a connection has been closed. 
+ 
+        :arg server_conn: is a server connection that has previously been 
+            passed to ``start_request``. 
+        """ 
+        pass 
+ 
+ 
+class HTTPMessageDelegate(object): 
+    """Implement this interface to handle an HTTP request or response. 
+ 
+    .. versionadded:: 4.0 
+    """ 
+    def headers_received(self, start_line, headers): 
+        """Called when the HTTP headers have been received and parsed. 
+ 
+        :arg start_line: a `.RequestStartLine` or `.ResponseStartLine` 
+            depending on whether this is a client or server message. 
+        :arg headers: a `.HTTPHeaders` instance. 
+ 
+        Some `.HTTPConnection` methods can only be called during 
+        ``headers_received``. 
+ 
+        May return a `.Future`; if it does the body will not be read 
+        until it is done. 
+        """ 
+        pass 
+ 
+    def data_received(self, chunk): 
+        """Called when a chunk of data has been received. 
+ 
+        May return a `.Future` for flow control. 
+        """ 
+        pass 
+ 
+    def finish(self): 
+        """Called after the last chunk of data has been received.""" 
+        pass 
+ 
+    def on_connection_close(self): 
+        """Called if the connection is closed without finishing the request. 
+ 
+        If ``headers_received`` is called, either ``finish`` or 
+        ``on_connection_close`` will be called, but not both. 
+        """ 
+        pass 
+ 
+ 
+class HTTPConnection(object): 
+    """Applications use this interface to write their responses. 
+ 
+    .. versionadded:: 4.0 
+    """ 
+    def write_headers(self, start_line, headers, chunk=None, callback=None): 
+        """Write an HTTP header block. 
+ 
+        :arg start_line: a `.RequestStartLine` or `.ResponseStartLine`. 
+        :arg headers: a `.HTTPHeaders` instance. 
+        :arg chunk: the first (optional) chunk of data.  This is an optimization 
+            so that small responses can be written in the same call as their 
+            headers. 
+        :arg callback: a callback to be run when the write is complete. 
+ 
+        The ``version`` field of ``start_line`` is ignored. 
+ 
+        Returns a `.Future` if no callback is given. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def write(self, chunk, callback=None): 
+        """Writes a chunk of body data. 
+ 
+        The callback will be run when the write is complete.  If no callback 
+        is given, returns a Future. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def finish(self): 
+        """Indicates that the last body data has been written. 
+        """ 
+        raise NotImplementedError() 
+ 
+ 
+def url_concat(url, args): 
+    """Concatenate url and arguments regardless of whether 
+    url has existing query parameters. 
+ 
+    ``args`` may be either a dictionary or a list of key-value pairs 
+    (the latter allows for multiple values with the same key. 
+ 
+    >>> url_concat("http://example.com/foo", dict(c="d")) 
+    'http://example.com/foo?c=d' 
+    >>> url_concat("http://example.com/foo?a=b", dict(c="d")) 
+    'http://example.com/foo?a=b&c=d' 
+    >>> url_concat("http://example.com/foo?a=b", [("c", "d"), ("c", "d2")]) 
+    'http://example.com/foo?a=b&c=d&c=d2' 
+    """ 
+    if args is None: 
+        return url 
+    parsed_url = urlparse(url) 
+    if isinstance(args, dict): 
+        parsed_query = parse_qsl(parsed_url.query, keep_blank_values=True) 
+        parsed_query.extend(args.items()) 
+    elif isinstance(args, list) or isinstance(args, tuple): 
+        parsed_query = parse_qsl(parsed_url.query, keep_blank_values=True) 
+        parsed_query.extend(args) 
+    else: 
+        err = "'args' parameter should be dict, list or tuple. Not {0}".format( 
+            type(args)) 
+        raise TypeError(err) 
+    final_query = urlencode(parsed_query) 
+    url = urlunparse(( 
+        parsed_url[0], 
+        parsed_url[1], 
+        parsed_url[2], 
+        parsed_url[3], 
+        final_query, 
+        parsed_url[5])) 
+    return url 
+ 
+ 
+class HTTPFile(ObjectDict): 
+    """Represents a file uploaded via a form. 
+ 
+    For backwards compatibility, its instance attributes are also 
+    accessible as dictionary keys. 
+ 
+    * ``filename`` 
+    * ``body`` 
+    * ``content_type`` 
+    """ 
+    pass 
+ 
+ 
+def _parse_request_range(range_header): 
+    """Parses a Range header. 
+ 
+    Returns either ``None`` or tuple ``(start, end)``. 
+    Note that while the HTTP headers use inclusive byte positions, 
+    this method returns indexes suitable for use in slices. 
+ 
+    >>> start, end = _parse_request_range("bytes=1-2") 
+    >>> start, end 
+    (1, 3) 
+    >>> [0, 1, 2, 3, 4][start:end] 
+    [1, 2] 
+    >>> _parse_request_range("bytes=6-") 
+    (6, None) 
+    >>> _parse_request_range("bytes=-6") 
+    (-6, None) 
+    >>> _parse_request_range("bytes=-0") 
+    (None, 0) 
+    >>> _parse_request_range("bytes=") 
+    (None, None) 
+    >>> _parse_request_range("foo=42") 
+    >>> _parse_request_range("bytes=1-2,6-10") 
+ 
+    Note: only supports one range (ex, ``bytes=1-2,6-10`` is not allowed). 
+ 
+    See [0] for the details of the range header. 
+ 
+    [0]: http://greenbytes.de/tech/webdav/draft-ietf-httpbis-p5-range-latest.html#byte.ranges 
+    """ 
+    unit, _, value = range_header.partition("=") 
+    unit, value = unit.strip(), value.strip() 
+    if unit != "bytes": 
+        return None 
+    start_b, _, end_b = value.partition("-") 
+    try: 
+        start = _int_or_none(start_b) 
+        end = _int_or_none(end_b) 
+    except ValueError: 
+        return None 
+    if end is not None: 
+        if start is None: 
+            if end != 0: 
+                start = -end 
+                end = None 
+        else: 
+            end += 1 
+    return (start, end) 
+ 
+ 
+def _get_content_range(start, end, total): 
+    """Returns a suitable Content-Range header: 
+ 
+    >>> print(_get_content_range(None, 1, 4)) 
+    bytes 0-0/4 
+    >>> print(_get_content_range(1, 3, 4)) 
+    bytes 1-2/4 
+    >>> print(_get_content_range(None, None, 4)) 
+    bytes 0-3/4 
+    """ 
+    start = start or 0 
+    end = (end or total) - 1 
+    return "bytes %s-%s/%s" % (start, end, total) 
+ 
+ 
+def _int_or_none(val): 
+    val = val.strip() 
+    if val == "": 
+        return None 
+    return int(val) 
+ 
+ 
+def parse_body_arguments(content_type, body, arguments, files, headers=None): 
+    """Parses a form request body. 
+ 
+    Supports ``application/x-www-form-urlencoded`` and 
+    ``multipart/form-data``.  The ``content_type`` parameter should be 
+    a string and ``body`` should be a byte string.  The ``arguments`` 
+    and ``files`` parameters are dictionaries that will be updated 
+    with the parsed contents. 
+    """ 
+    if headers and 'Content-Encoding' in headers: 
+        gen_log.warning("Unsupported Content-Encoding: %s", 
+                        headers['Content-Encoding']) 
+        return 
+    if content_type.startswith("application/x-www-form-urlencoded"): 
+        try: 
+            uri_arguments = parse_qs_bytes(native_str(body), keep_blank_values=True) 
+        except Exception as e: 
+            gen_log.warning('Invalid x-www-form-urlencoded body: %s', e) 
+            uri_arguments = {} 
+        for name, values in uri_arguments.items(): 
+            if values: 
+                arguments.setdefault(name, []).extend(values) 
+    elif content_type.startswith("multipart/form-data"): 
+        try: 
+            fields = content_type.split(";") 
+            for field in fields: 
+                k, sep, v = field.strip().partition("=") 
+                if k == "boundary" and v: 
+                    parse_multipart_form_data(utf8(v), body, arguments, files) 
+                    break 
+            else: 
+                raise ValueError("multipart boundary not found") 
+        except Exception as e: 
+            gen_log.warning("Invalid multipart/form-data: %s", e) 
+ 
+ 
+def parse_multipart_form_data(boundary, data, arguments, files): 
+    """Parses a ``multipart/form-data`` body. 
+ 
+    The ``boundary`` and ``data`` parameters are both byte strings. 
+    The dictionaries given in the arguments and files parameters 
+    will be updated with the contents of the body. 
+    """ 
+    # The standard allows for the boundary to be quoted in the header, 
+    # although it's rare (it happens at least for google app engine 
+    # xmpp).  I think we're also supposed to handle backslash-escapes 
+    # here but I'll save that until we see a client that uses them 
+    # in the wild. 
+    if boundary.startswith(b'"') and boundary.endswith(b'"'): 
+        boundary = boundary[1:-1] 
+    final_boundary_index = data.rfind(b"--" + boundary + b"--") 
+    if final_boundary_index == -1: 
+        gen_log.warning("Invalid multipart/form-data: no final boundary") 
+        return 
+    parts = data[:final_boundary_index].split(b"--" + boundary + b"\r\n") 
+    for part in parts: 
+        if not part: 
+            continue 
+        eoh = part.find(b"\r\n\r\n") 
+        if eoh == -1: 
+            gen_log.warning("multipart/form-data missing headers") 
+            continue 
+        headers = HTTPHeaders.parse(part[:eoh].decode("utf-8")) 
+        disp_header = headers.get("Content-Disposition", "") 
+        disposition, disp_params = _parse_header(disp_header) 
+        if disposition != "form-data" or not part.endswith(b"\r\n"): 
+            gen_log.warning("Invalid multipart/form-data") 
+            continue 
+        value = part[eoh + 4:-2] 
+        if not disp_params.get("name"): 
+            gen_log.warning("multipart/form-data value missing name") 
+            continue 
+        name = disp_params["name"] 
+        if disp_params.get("filename"): 
+            ctype = headers.get("Content-Type", "application/unknown") 
+            files.setdefault(name, []).append(HTTPFile(  # type: ignore 
+                filename=disp_params["filename"], body=value, 
+                content_type=ctype)) 
+        else: 
+            arguments.setdefault(name, []).append(value) 
+ 
+ 
+def format_timestamp(ts): 
+    """Formats a timestamp in the format used by HTTP. 
+ 
+    The argument may be a numeric timestamp as returned by `time.time`, 
+    a time tuple as returned by `time.gmtime`, or a `datetime.datetime` 
+    object. 
+ 
+    >>> format_timestamp(1359312200) 
+    'Sun, 27 Jan 2013 18:43:20 GMT' 
+    """ 
+    if isinstance(ts, numbers.Real): 
+        pass 
+    elif isinstance(ts, (tuple, time.struct_time)): 
+        ts = calendar.timegm(ts) 
+    elif isinstance(ts, datetime.datetime): 
+        ts = calendar.timegm(ts.utctimetuple()) 
+    else: 
+        raise TypeError("unknown timestamp type: %r" % ts) 
+    return email.utils.formatdate(ts, usegmt=True) 
+ 
+ 
+RequestStartLine = collections.namedtuple( 
+    'RequestStartLine', ['method', 'path', 'version']) 
+ 
+ 
+def parse_request_start_line(line): 
+    """Returns a (method, path, version) tuple for an HTTP 1.x request line. 
+ 
+    The response is a `collections.namedtuple`. 
+ 
+    >>> parse_request_start_line("GET /foo HTTP/1.1") 
+    RequestStartLine(method='GET', path='/foo', version='HTTP/1.1') 
+    """ 
+    try: 
+        method, path, version = line.split(" ") 
+    except ValueError: 
+        raise HTTPInputError("Malformed HTTP request line") 
+    if not re.match(r"^HTTP/1\.[0-9]$", version): 
+        raise HTTPInputError( 
+            "Malformed HTTP version in HTTP Request-Line: %r" % version) 
+    return RequestStartLine(method, path, version) 
+ 
+ 
+ResponseStartLine = collections.namedtuple( 
+    'ResponseStartLine', ['version', 'code', 'reason']) 
+ 
+ 
+def parse_response_start_line(line): 
+    """Returns a (version, code, reason) tuple for an HTTP 1.x response line. 
+ 
+    The response is a `collections.namedtuple`. 
+ 
+    >>> parse_response_start_line("HTTP/1.1 200 OK") 
+    ResponseStartLine(version='HTTP/1.1', code=200, reason='OK') 
+    """ 
+    line = native_str(line) 
+    match = re.match("(HTTP/1.[0-9]) ([0-9]+) ([^\r]*)", line) 
+    if not match: 
+        raise HTTPInputError("Error parsing response start line") 
+    return ResponseStartLine(match.group(1), int(match.group(2)), 
+                             match.group(3)) 
+ 
+# _parseparam and _parse_header are copied and modified from python2.7's cgi.py 
+# The original 2.7 version of this code did not correctly support some 
+# combinations of semicolons and double quotes. 
+# It has also been modified to support valueless parameters as seen in 
+# websocket extension negotiations. 
+ 
+ 
+def _parseparam(s): 
+    while s[:1] == ';': 
+        s = s[1:] 
+        end = s.find(';') 
+        while end > 0 and (s.count('"', 0, end) - s.count('\\"', 0, end)) % 2: 
+            end = s.find(';', end + 1) 
+        if end < 0: 
+            end = len(s) 
+        f = s[:end] 
+        yield f.strip() 
+        s = s[end:] 
+ 
+ 
+def _parse_header(line): 
+    """Parse a Content-type like header. 
+ 
+    Return the main content-type and a dictionary of options. 
+ 
+    """ 
+    parts = _parseparam(';' + line) 
+    key = next(parts) 
+    pdict = {} 
+    for p in parts: 
+        i = p.find('=') 
+        if i >= 0: 
+            name = p[:i].strip().lower() 
+            value = p[i + 1:].strip() 
+            if len(value) >= 2 and value[0] == value[-1] == '"': 
+                value = value[1:-1] 
+                value = value.replace('\\\\', '\\').replace('\\"', '"') 
+            pdict[name] = value 
+        else: 
+            pdict[p] = None 
+    return key, pdict 
+ 
+ 
+def _encode_header(key, pdict): 
+    """Inverse of _parse_header. 
+ 
+    >>> _encode_header('permessage-deflate', 
+    ...     {'client_max_window_bits': 15, 'client_no_context_takeover': None}) 
+    'permessage-deflate; client_max_window_bits=15; client_no_context_takeover' 
+    """ 
+    if not pdict: 
+        return key 
+    out = [key] 
+    # Sort the parameters just to make it easy to test. 
+    for k, v in sorted(pdict.items()): 
+        if v is None: 
+            out.append(k) 
+        else: 
+            # TODO: quote if necessary. 
+            out.append('%s=%s' % (k, v)) 
+    return '; '.join(out) 
+ 
+ 
+def doctests(): 
+    import doctest 
+    return doctest.DocTestSuite() 
+ 
+ 
+def split_host_and_port(netloc): 
+    """Returns ``(host, port)`` tuple from ``netloc``. 
+ 
+    Returned ``port`` will be ``None`` if not present. 
+ 
+    .. versionadded:: 4.1 
+    """ 
+    match = re.match(r'^(.+):(\d+)$', netloc) 
+    if match: 
+        host = match.group(1) 
+        port = int(match.group(2)) 
+    else: 
+        host = netloc 
+        port = None 
+    return (host, port) 
+ 
+ 
+_OctalPatt = re.compile(r"\\[0-3][0-7][0-7]") 
+_QuotePatt = re.compile(r"[\\].") 
+_nulljoin = ''.join 
+ 
+ 
+def _unquote_cookie(str): 
+    """Handle double quotes and escaping in cookie values. 
+ 
+    This method is copied verbatim from the Python 3.5 standard 
+    library (http.cookies._unquote) so we don't have to depend on 
+    non-public interfaces. 
+    """ 
+    # If there aren't any doublequotes, 
+    # then there can't be any special characters.  See RFC 2109. 
+    if str is None or len(str) < 2: 
+        return str 
+    if str[0] != '"' or str[-1] != '"': 
+        return str 
+ 
+    # We have to assume that we must decode this string. 
+    # Down to work. 
+ 
+    # Remove the "s 
+    str = str[1:-1] 
+ 
+    # Check for special sequences.  Examples: 
+    #    \012 --> \n 
+    #    \"   --> " 
+    # 
+    i = 0 
+    n = len(str) 
+    res = [] 
+    while 0 <= i < n: 
+        o_match = _OctalPatt.search(str, i) 
+        q_match = _QuotePatt.search(str, i) 
+        if not o_match and not q_match:              # Neither matched 
+            res.append(str[i:]) 
+            break 
+        # else: 
+        j = k = -1 
+        if o_match: 
+            j = o_match.start(0) 
+        if q_match: 
+            k = q_match.start(0) 
+        if q_match and (not o_match or k < j):     # QuotePatt matched 
+            res.append(str[i:k]) 
+            res.append(str[k + 1]) 
+            i = k + 2 
+        else:                                      # OctalPatt matched 
+            res.append(str[i:j]) 
+            res.append(chr(int(str[j + 1:j + 4], 8))) 
+            i = j + 4 
+    return _nulljoin(res) 
+ 
+ 
+def parse_cookie(cookie): 
+    """Parse a ``Cookie`` HTTP header into a dict of name/value pairs. 
+ 
+    This function attempts to mimic browser cookie parsing behavior; 
+    it specifically does not follow any of the cookie-related RFCs 
+    (because browsers don't either). 
+ 
+    The algorithm used is identical to that used by Django version 1.9.10. 
+ 
+    .. versionadded:: 4.4.2 
+    """ 
+    cookiedict = {} 
+    for chunk in cookie.split(str(';')): 
+        if str('=') in chunk: 
+            key, val = chunk.split(str('='), 1) 
+        else: 
+            # Assume an empty name per 
+            # https://bugzilla.mozilla.org/show_bug.cgi?id=169091 
+            key, val = str(''), chunk 
+        key, val = key.strip(), val.strip() 
+        if key or val: 
+            # unquote using Python's algorithm. 
+            cookiedict[key] = _unquote_cookie(val) 
+    return cookiedict 
diff --git a/contrib/python/tornado/tornado-4/tornado/ioloop.py b/contrib/python/tornado/tornado-4/tornado/ioloop.py
index ad35787fca..3dd129bb74 100644
--- a/contrib/python/tornado/tornado-4/tornado/ioloop.py
+++ b/contrib/python/tornado/tornado-4/tornado/ioloop.py
@@ -1,1041 +1,1041 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""An I/O event loop for non-blocking sockets.
-
-Typical applications will use a single `IOLoop` object, in the
-`IOLoop.instance` singleton.  The `IOLoop.start` method should usually
-be called at the end of the ``main()`` function.  Atypical applications may
-use more than one `IOLoop`, such as one `IOLoop` per thread, or per `unittest`
-case.
-
-In addition to I/O events, the `IOLoop` can also schedule time-based events.
-`IOLoop.add_timeout` is a non-blocking alternative to `time.sleep`.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import collections
-import datetime
-import errno
-import functools
-import heapq
-import itertools
-import logging
-import numbers
-import os
-import select
-import sys
-import threading
-import time
-import traceback
-import math
-
-from tornado.concurrent import TracebackFuture, is_future
-from tornado.log import app_log, gen_log
-from tornado.platform.auto import set_close_exec, Waker
-from tornado import stack_context
-from tornado.util import PY3, Configurable, errno_from_exception, timedelta_to_seconds
-
-try:
-    import signal
-except ImportError:
-    signal = None
-
-
-if PY3:
-    import _thread as thread
-else:
-    import thread
-
-
-_POLL_TIMEOUT = 3600.0
-
-
-class TimeoutError(Exception):
-    pass
-
-
-class IOLoop(Configurable):
-    """A level-triggered I/O loop.
-
-    We use ``epoll`` (Linux) or ``kqueue`` (BSD and Mac OS X) if they
-    are available, or else we fall back on select(). If you are
-    implementing a system that needs to handle thousands of
-    simultaneous connections, you should use a system that supports
-    either ``epoll`` or ``kqueue``.
-
-    Example usage for a simple TCP server:
-
-    .. testcode::
-
-        import errno
-        import functools
-        import tornado.ioloop
-        import socket
-
-        def connection_ready(sock, fd, events):
-            while True:
-                try:
-                    connection, address = sock.accept()
-                except socket.error as e:
-                    if e.args[0] not in (errno.EWOULDBLOCK, errno.EAGAIN):
-                        raise
-                    return
-                connection.setblocking(0)
-                handle_connection(connection, address)
-
-        if __name__ == '__main__':
-            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
-            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-            sock.setblocking(0)
-            sock.bind(("", port))
-            sock.listen(128)
-
-            io_loop = tornado.ioloop.IOLoop.current()
-            callback = functools.partial(connection_ready, sock)
-            io_loop.add_handler(sock.fileno(), callback, io_loop.READ)
-            io_loop.start()
-
-    .. testoutput::
-       :hide:
-
-    By default, a newly-constructed `IOLoop` becomes the thread's current
-    `IOLoop`, unless there already is a current `IOLoop`. This behavior
-    can be controlled with the ``make_current`` argument to the `IOLoop`
-    constructor: if ``make_current=True``, the new `IOLoop` will always
-    try to become current and it raises an error if there is already a
-    current instance. If ``make_current=False``, the new `IOLoop` will
-    not try to become current.
-
-    .. versionchanged:: 4.2
-       Added the ``make_current`` keyword argument to the `IOLoop`
-       constructor.
-    """
-    # Constants from the epoll module
-    _EPOLLIN = 0x001
-    _EPOLLPRI = 0x002
-    _EPOLLOUT = 0x004
-    _EPOLLERR = 0x008
-    _EPOLLHUP = 0x010
-    _EPOLLRDHUP = 0x2000
-    _EPOLLONESHOT = (1 << 30)
-    _EPOLLET = (1 << 31)
-
-    # Our events map exactly to the epoll events
-    NONE = 0
-    READ = _EPOLLIN
-    WRITE = _EPOLLOUT
-    ERROR = _EPOLLERR | _EPOLLHUP
-
-    # Global lock for creating global IOLoop instance
-    _instance_lock = threading.Lock()
-
-    _current = threading.local()
-
-    @staticmethod
-    def instance():
-        """Returns a global `IOLoop` instance.
-
-        Most applications have a single, global `IOLoop` running on the
-        main thread.  Use this method to get this instance from
-        another thread.  In most other cases, it is better to use `current()`
-        to get the current thread's `IOLoop`.
-        """
-        if not hasattr(IOLoop, "_instance"):
-            with IOLoop._instance_lock:
-                if not hasattr(IOLoop, "_instance"):
-                    # New instance after double check
-                    IOLoop._instance = IOLoop()
-        return IOLoop._instance
-
-    @staticmethod
-    def initialized():
-        """Returns true if the singleton instance has been created."""
-        return hasattr(IOLoop, "_instance")
-
-    def install(self):
-        """Installs this `IOLoop` object as the singleton instance.
-
-        This is normally not necessary as `instance()` will create
-        an `IOLoop` on demand, but you may want to call `install` to use
-        a custom subclass of `IOLoop`.
-
-        When using an `IOLoop` subclass, `install` must be called prior
-        to creating any objects that implicitly create their own
-        `IOLoop` (e.g., :class:`tornado.httpclient.AsyncHTTPClient`).
-        """
-        assert not IOLoop.initialized()
-        IOLoop._instance = self
-
-    @staticmethod
-    def clear_instance():
-        """Clear the global `IOLoop` instance.
-
-        .. versionadded:: 4.0
-        """
-        if hasattr(IOLoop, "_instance"):
-            del IOLoop._instance
-
-    @staticmethod
-    def current(instance=True):
-        """Returns the current thread's `IOLoop`.
-
-        If an `IOLoop` is currently running or has been marked as
-        current by `make_current`, returns that instance.  If there is
-        no current `IOLoop`, returns `IOLoop.instance()` (i.e. the
-        main thread's `IOLoop`, creating one if necessary) if ``instance``
-        is true.
-
-        In general you should use `IOLoop.current` as the default when
-        constructing an asynchronous object, and use `IOLoop.instance`
-        when you mean to communicate to the main thread from a different
-        one.
-
-        .. versionchanged:: 4.1
-           Added ``instance`` argument to control the fallback to
-           `IOLoop.instance()`.
-        """
-        current = getattr(IOLoop._current, "instance", None)
-        if current is None and instance:
-            return IOLoop.instance()
-        return current
-
-    def make_current(self):
-        """Makes this the `IOLoop` for the current thread.
-
-        An `IOLoop` automatically becomes current for its thread
-        when it is started, but it is sometimes useful to call
-        `make_current` explicitly before starting the `IOLoop`,
-        so that code run at startup time can find the right
-        instance.
-
-        .. versionchanged:: 4.1
-           An `IOLoop` created while there is no current `IOLoop`
-           will automatically become current.
-        """
-        IOLoop._current.instance = self
-
-    @staticmethod
-    def clear_current():
-        IOLoop._current.instance = None
-
-    @classmethod
-    def configurable_base(cls):
-        return IOLoop
-
-    @classmethod
-    def configurable_default(cls):
-        if hasattr(select, "epoll"):
-            from tornado.platform.epoll import EPollIOLoop
-            return EPollIOLoop
-        if hasattr(select, "kqueue"):
-            # Python 2.6+ on BSD or Mac
-            from tornado.platform.kqueue import KQueueIOLoop
-            return KQueueIOLoop
-        from tornado.platform.select import SelectIOLoop
-        return SelectIOLoop
-
-    def initialize(self, make_current=None):
-        if make_current is None:
-            if IOLoop.current(instance=False) is None:
-                self.make_current()
-        elif make_current:
-            if IOLoop.current(instance=False) is not None:
-                raise RuntimeError("current IOLoop already exists")
-            self.make_current()
-
-    def close(self, all_fds=False):
-        """Closes the `IOLoop`, freeing any resources used.
-
-        If ``all_fds`` is true, all file descriptors registered on the
-        IOLoop will be closed (not just the ones created by the
-        `IOLoop` itself).
-
-        Many applications will only use a single `IOLoop` that runs for the
-        entire lifetime of the process.  In that case closing the `IOLoop`
-        is not necessary since everything will be cleaned up when the
-        process exits.  `IOLoop.close` is provided mainly for scenarios
-        such as unit tests, which create and destroy a large number of
-        ``IOLoops``.
-
-        An `IOLoop` must be completely stopped before it can be closed.  This
-        means that `IOLoop.stop()` must be called *and* `IOLoop.start()` must
-        be allowed to return before attempting to call `IOLoop.close()`.
-        Therefore the call to `close` will usually appear just after
-        the call to `start` rather than near the call to `stop`.
-
-        .. versionchanged:: 3.1
-           If the `IOLoop` implementation supports non-integer objects
-           for "file descriptors", those objects will have their
-           ``close`` method when ``all_fds`` is true.
-        """
-        raise NotImplementedError()
-
-    def add_handler(self, fd, handler, events):
-        """Registers the given handler to receive the given events for ``fd``.
-
-        The ``fd`` argument may either be an integer file descriptor or
-        a file-like object with a ``fileno()`` method (and optionally a
-        ``close()`` method, which may be called when the `IOLoop` is shut
-        down).
-
-        The ``events`` argument is a bitwise or of the constants
-        ``IOLoop.READ``, ``IOLoop.WRITE``, and ``IOLoop.ERROR``.
-
-        When an event occurs, ``handler(fd, events)`` will be run.
-
-        .. versionchanged:: 4.0
-           Added the ability to pass file-like objects in addition to
-           raw file descriptors.
-        """
-        raise NotImplementedError()
-
-    def update_handler(self, fd, events):
-        """Changes the events we listen for ``fd``.
-
-        .. versionchanged:: 4.0
-           Added the ability to pass file-like objects in addition to
-           raw file descriptors.
-        """
-        raise NotImplementedError()
-
-    def remove_handler(self, fd):
-        """Stop listening for events on ``fd``.
-
-        .. versionchanged:: 4.0
-           Added the ability to pass file-like objects in addition to
-           raw file descriptors.
-        """
-        raise NotImplementedError()
-
-    def set_blocking_signal_threshold(self, seconds, action):
-        """Sends a signal if the `IOLoop` is blocked for more than
-        ``s`` seconds.
-
-        Pass ``seconds=None`` to disable.  Requires Python 2.6 on a unixy
-        platform.
-
-        The action parameter is a Python signal handler.  Read the
-        documentation for the `signal` module for more information.
-        If ``action`` is None, the process will be killed if it is
-        blocked for too long.
-        """
-        raise NotImplementedError()
-
-    def set_blocking_log_threshold(self, seconds):
-        """Logs a stack trace if the `IOLoop` is blocked for more than
-        ``s`` seconds.
-
-        Equivalent to ``set_blocking_signal_threshold(seconds,
-        self.log_stack)``
-        """
-        self.set_blocking_signal_threshold(seconds, self.log_stack)
-
-    def log_stack(self, signal, frame):
-        """Signal handler to log the stack trace of the current thread.
-
-        For use with `set_blocking_signal_threshold`.
-        """
-        gen_log.warning('IOLoop blocked for %f seconds in\n%s',
-                        self._blocking_signal_threshold,
-                        ''.join(traceback.format_stack(frame)))
-
-    def start(self):
-        """Starts the I/O loop.
-
-        The loop will run until one of the callbacks calls `stop()`, which
-        will make the loop stop after the current event iteration completes.
-        """
-        raise NotImplementedError()
-
-    def _setup_logging(self):
-        """The IOLoop catches and logs exceptions, so it's
-        important that log output be visible.  However, python's
-        default behavior for non-root loggers (prior to python
-        3.2) is to print an unhelpful "no handlers could be
-        found" message rather than the actual log entry, so we
-        must explicitly configure logging if we've made it this
-        far without anything.
-
-        This method should be called from start() in subclasses.
-        """
-        if not any([logging.getLogger().handlers,
-                    logging.getLogger('tornado').handlers,
-                    logging.getLogger('tornado.application').handlers]):
-            logging.basicConfig()
-
-    def stop(self):
-        """Stop the I/O loop.
-
-        If the event loop is not currently running, the next call to `start()`
-        will return immediately.
-
-        To use asynchronous methods from otherwise-synchronous code (such as
-        unit tests), you can start and stop the event loop like this::
-
-          ioloop = IOLoop()
-          async_method(ioloop=ioloop, callback=ioloop.stop)
-          ioloop.start()
-
-        ``ioloop.start()`` will return after ``async_method`` has run
-        its callback, whether that callback was invoked before or
-        after ``ioloop.start``.
-
-        Note that even after `stop` has been called, the `IOLoop` is not
-        completely stopped until `IOLoop.start` has also returned.
-        Some work that was scheduled before the call to `stop` may still
-        be run before the `IOLoop` shuts down.
-        """
-        raise NotImplementedError()
-
-    def run_sync(self, func, timeout=None):
-        """Starts the `IOLoop`, runs the given function, and stops the loop.
-
-        The function must return either a yieldable object or
-        ``None``. If the function returns a yieldable object, the
-        `IOLoop` will run until the yieldable is resolved (and
-        `run_sync()` will return the yieldable's result). If it raises
-        an exception, the `IOLoop` will stop and the exception will be
-        re-raised to the caller.
-
-        The keyword-only argument ``timeout`` may be used to set
-        a maximum duration for the function.  If the timeout expires,
-        a `TimeoutError` is raised.
-
-        This method is useful in conjunction with `tornado.gen.coroutine`
-        to allow asynchronous calls in a ``main()`` function::
-
-            @gen.coroutine
-            def main():
-                # do stuff...
-
-            if __name__ == '__main__':
-                IOLoop.current().run_sync(main)
-
-        .. versionchanged:: 4.3
-           Returning a non-``None``, non-yieldable value is now an error.
-        """
-        future_cell = [None]
-
-        def run():
-            try:
-                result = func()
-                if result is not None:
-                    from tornado.gen import convert_yielded
-                    result = convert_yielded(result)
-            except Exception:
-                future_cell[0] = TracebackFuture()
-                future_cell[0].set_exc_info(sys.exc_info())
-            else:
-                if is_future(result):
-                    future_cell[0] = result
-                else:
-                    future_cell[0] = TracebackFuture()
-                    future_cell[0].set_result(result)
-            self.add_future(future_cell[0], lambda future: self.stop())
-        self.add_callback(run)
-        if timeout is not None:
-            timeout_handle = self.add_timeout(self.time() + timeout, self.stop)
-        self.start()
-        if timeout is not None:
-            self.remove_timeout(timeout_handle)
-        if not future_cell[0].done():
-            raise TimeoutError('Operation timed out after %s seconds' % timeout)
-        return future_cell[0].result()
-
-    def time(self):
-        """Returns the current time according to the `IOLoop`'s clock.
-
-        The return value is a floating-point number relative to an
-        unspecified time in the past.
-
-        By default, the `IOLoop`'s time function is `time.time`.  However,
-        it may be configured to use e.g. `time.monotonic` instead.
-        Calls to `add_timeout` that pass a number instead of a
-        `datetime.timedelta` should use this function to compute the
-        appropriate time, so they can work no matter what time function
-        is chosen.
-        """
-        return time.time()
-
-    def add_timeout(self, deadline, callback, *args, **kwargs):
-        """Runs the ``callback`` at the time ``deadline`` from the I/O loop.
-
-        Returns an opaque handle that may be passed to
-        `remove_timeout` to cancel.
-
-        ``deadline`` may be a number denoting a time (on the same
-        scale as `IOLoop.time`, normally `time.time`), or a
-        `datetime.timedelta` object for a deadline relative to the
-        current time.  Since Tornado 4.0, `call_later` is a more
-        convenient alternative for the relative case since it does not
-        require a timedelta object.
-
-        Note that it is not safe to call `add_timeout` from other threads.
-        Instead, you must use `add_callback` to transfer control to the
-        `IOLoop`'s thread, and then call `add_timeout` from there.
-
-        Subclasses of IOLoop must implement either `add_timeout` or
-        `call_at`; the default implementations of each will call
-        the other.  `call_at` is usually easier to implement, but
-        subclasses that wish to maintain compatibility with Tornado
-        versions prior to 4.0 must use `add_timeout` instead.
-
-        .. versionchanged:: 4.0
-           Now passes through ``*args`` and ``**kwargs`` to the callback.
-        """
-        if isinstance(deadline, numbers.Real):
-            return self.call_at(deadline, callback, *args, **kwargs)
-        elif isinstance(deadline, datetime.timedelta):
-            return self.call_at(self.time() + timedelta_to_seconds(deadline),
-                                callback, *args, **kwargs)
-        else:
-            raise TypeError("Unsupported deadline %r" % deadline)
-
-    def call_later(self, delay, callback, *args, **kwargs):
-        """Runs the ``callback`` after ``delay`` seconds have passed.
-
-        Returns an opaque handle that may be passed to `remove_timeout`
-        to cancel.  Note that unlike the `asyncio` method of the same
-        name, the returned object does not have a ``cancel()`` method.
-
-        See `add_timeout` for comments on thread-safety and subclassing.
-
-        .. versionadded:: 4.0
-        """
-        return self.call_at(self.time() + delay, callback, *args, **kwargs)
-
-    def call_at(self, when, callback, *args, **kwargs):
-        """Runs the ``callback`` at the absolute time designated by ``when``.
-
-        ``when`` must be a number using the same reference point as
-        `IOLoop.time`.
-
-        Returns an opaque handle that may be passed to `remove_timeout`
-        to cancel.  Note that unlike the `asyncio` method of the same
-        name, the returned object does not have a ``cancel()`` method.
-
-        See `add_timeout` for comments on thread-safety and subclassing.
-
-        .. versionadded:: 4.0
-        """
-        return self.add_timeout(when, callback, *args, **kwargs)
-
-    def remove_timeout(self, timeout):
-        """Cancels a pending timeout.
-
-        The argument is a handle as returned by `add_timeout`.  It is
-        safe to call `remove_timeout` even if the callback has already
-        been run.
-        """
-        raise NotImplementedError()
-
-    def add_callback(self, callback, *args, **kwargs):
-        """Calls the given callback on the next I/O loop iteration.
-
-        It is safe to call this method from any thread at any time,
-        except from a signal handler.  Note that this is the **only**
-        method in `IOLoop` that makes this thread-safety guarantee; all
-        other interaction with the `IOLoop` must be done from that
-        `IOLoop`'s thread.  `add_callback()` may be used to transfer
-        control from other threads to the `IOLoop`'s thread.
-
-        To add a callback from a signal handler, see
-        `add_callback_from_signal`.
-        """
-        raise NotImplementedError()
-
-    def add_callback_from_signal(self, callback, *args, **kwargs):
-        """Calls the given callback on the next I/O loop iteration.
-
-        Safe for use from a Python signal handler; should not be used
-        otherwise.
-
-        Callbacks added with this method will be run without any
-        `.stack_context`, to avoid picking up the context of the function
-        that was interrupted by the signal.
-        """
-        raise NotImplementedError()
-
-    def spawn_callback(self, callback, *args, **kwargs):
-        """Calls the given callback on the next IOLoop iteration.
-
-        Unlike all other callback-related methods on IOLoop,
-        ``spawn_callback`` does not associate the callback with its caller's
-        ``stack_context``, so it is suitable for fire-and-forget callbacks
-        that should not interfere with the caller.
-
-        .. versionadded:: 4.0
-        """
-        with stack_context.NullContext():
-            self.add_callback(callback, *args, **kwargs)
-
-    def add_future(self, future, callback):
-        """Schedules a callback on the ``IOLoop`` when the given
-        `.Future` is finished.
-
-        The callback is invoked with one argument, the
-        `.Future`.
-        """
-        assert is_future(future)
-        callback = stack_context.wrap(callback)
-        future.add_done_callback(
-            lambda future: self.add_callback(callback, future))
-
-    def _run_callback(self, callback):
-        """Runs a callback with error handling.
-
-        For use in subclasses.
-        """
-        try:
-            ret = callback()
-            if ret is not None:
-                from tornado import gen
-                # Functions that return Futures typically swallow all
-                # exceptions and store them in the Future.  If a Future
-                # makes it out to the IOLoop, ensure its exception (if any)
-                # gets logged too.
-                try:
-                    ret = gen.convert_yielded(ret)
-                except gen.BadYieldError:
-                    # It's not unusual for add_callback to be used with
-                    # methods returning a non-None and non-yieldable
-                    # result, which should just be ignored.
-                    pass
-                else:
-                    self.add_future(ret, self._discard_future_result)
-        except Exception:
-            self.handle_callback_exception(callback)
-
-    def _discard_future_result(self, future):
-        """Avoid unhandled-exception warnings from spawned coroutines."""
-        future.result()
-
-    def handle_callback_exception(self, callback):
-        """This method is called whenever a callback run by the `IOLoop`
-        throws an exception.
-
-        By default simply logs the exception as an error.  Subclasses
-        may override this method to customize reporting of exceptions.
-
-        The exception itself is not passed explicitly, but is available
-        in `sys.exc_info`.
-        """
-        app_log.error("Exception in callback %r", callback, exc_info=True)
-
-    def split_fd(self, fd):
-        """Returns an (fd, obj) pair from an ``fd`` parameter.
-
-        We accept both raw file descriptors and file-like objects as
-        input to `add_handler` and related methods.  When a file-like
-        object is passed, we must retain the object itself so we can
-        close it correctly when the `IOLoop` shuts down, but the
-        poller interfaces favor file descriptors (they will accept
-        file-like objects and call ``fileno()`` for you, but they
-        always return the descriptor itself).
-
-        This method is provided for use by `IOLoop` subclasses and should
-        not generally be used by application code.
-
-        .. versionadded:: 4.0
-        """
-        try:
-            return fd.fileno(), fd
-        except AttributeError:
-            return fd, fd
-
-    def close_fd(self, fd):
-        """Utility method to close an ``fd``.
-
-        If ``fd`` is a file-like object, we close it directly; otherwise
-        we use `os.close`.
-
-        This method is provided for use by `IOLoop` subclasses (in
-        implementations of ``IOLoop.close(all_fds=True)`` and should
-        not generally be used by application code.
-
-        .. versionadded:: 4.0
-        """
-        try:
-            try:
-                fd.close()
-            except AttributeError:
-                os.close(fd)
-        except OSError:
-            pass
-
-
-class PollIOLoop(IOLoop):
-    """Base class for IOLoops built around a select-like function.
-
-    For concrete implementations, see `tornado.platform.epoll.EPollIOLoop`
-    (Linux), `tornado.platform.kqueue.KQueueIOLoop` (BSD and Mac), or
-    `tornado.platform.select.SelectIOLoop` (all platforms).
-    """
-    def initialize(self, impl, time_func=None, **kwargs):
-        super(PollIOLoop, self).initialize(**kwargs)
-        self._impl = impl
-        if hasattr(self._impl, 'fileno'):
-            set_close_exec(self._impl.fileno())
-        self.time_func = time_func or time.time
-        self._handlers = {}
-        self._events = {}
-        self._callbacks = collections.deque()
-        self._timeouts = []
-        self._cancellations = 0
-        self._running = False
-        self._stopped = False
-        self._closing = False
-        self._thread_ident = None
-        self._blocking_signal_threshold = None
-        self._timeout_counter = itertools.count()
-
-        # Create a pipe that we send bogus data to when we want to wake
-        # the I/O loop when it is idle
-        self._waker = Waker()
-        self.add_handler(self._waker.fileno(),
-                         lambda fd, events: self._waker.consume(),
-                         self.READ)
-
-    def close(self, all_fds=False):
-        self._closing = True
-        self.remove_handler(self._waker.fileno())
-        if all_fds:
-            for fd, handler in list(self._handlers.values()):
-                self.close_fd(fd)
-        self._waker.close()
-        self._impl.close()
-        self._callbacks = None
-        self._timeouts = None
-
-    def add_handler(self, fd, handler, events):
-        fd, obj = self.split_fd(fd)
-        self._handlers[fd] = (obj, stack_context.wrap(handler))
-        self._impl.register(fd, events | self.ERROR)
-
-    def update_handler(self, fd, events):
-        fd, obj = self.split_fd(fd)
-        self._impl.modify(fd, events | self.ERROR)
-
-    def remove_handler(self, fd):
-        fd, obj = self.split_fd(fd)
-        self._handlers.pop(fd, None)
-        self._events.pop(fd, None)
-        try:
-            self._impl.unregister(fd)
-        except Exception:
-            gen_log.debug("Error deleting fd from IOLoop", exc_info=True)
-
-    def set_blocking_signal_threshold(self, seconds, action):
-        if not hasattr(signal, "setitimer"):
-            gen_log.error("set_blocking_signal_threshold requires a signal module "
-                          "with the setitimer method")
-            return
-        self._blocking_signal_threshold = seconds
-        if seconds is not None:
-            signal.signal(signal.SIGALRM,
-                          action if action is not None else signal.SIG_DFL)
-
-    def start(self):
-        if self._running:
-            raise RuntimeError("IOLoop is already running")
-        self._setup_logging()
-        if self._stopped:
-            self._stopped = False
-            return
-        old_current = getattr(IOLoop._current, "instance", None)
-        IOLoop._current.instance = self
-        self._thread_ident = thread.get_ident()
-        self._running = True
-
-        # signal.set_wakeup_fd closes a race condition in event loops:
-        # a signal may arrive at the beginning of select/poll/etc
-        # before it goes into its interruptible sleep, so the signal
-        # will be consumed without waking the select.  The solution is
-        # for the (C, synchronous) signal handler to write to a pipe,
-        # which will then be seen by select.
-        #
-        # In python's signal handling semantics, this only matters on the
-        # main thread (fortunately, set_wakeup_fd only works on the main
-        # thread and will raise a ValueError otherwise).
-        #
-        # If someone has already set a wakeup fd, we don't want to
-        # disturb it.  This is an issue for twisted, which does its
-        # SIGCHLD processing in response to its own wakeup fd being
-        # written to.  As long as the wakeup fd is registered on the IOLoop,
-        # the loop will still wake up and everything should work.
-        old_wakeup_fd = None
-        if hasattr(signal, 'set_wakeup_fd') and os.name == 'posix':
-            # requires python 2.6+, unix.  set_wakeup_fd exists but crashes
-            # the python process on windows.
-            try:
-                old_wakeup_fd = signal.set_wakeup_fd(self._waker.write_fileno())
-                if old_wakeup_fd != -1:
-                    # Already set, restore previous value.  This is a little racy,
-                    # but there's no clean get_wakeup_fd and in real use the
-                    # IOLoop is just started once at the beginning.
-                    signal.set_wakeup_fd(old_wakeup_fd)
-                    old_wakeup_fd = None
-            except ValueError:
-                # Non-main thread, or the previous value of wakeup_fd
-                # is no longer valid.
-                old_wakeup_fd = None
-
-        try:
-            while True:
-                # Prevent IO event starvation by delaying new callbacks
-                # to the next iteration of the event loop.
-                ncallbacks = len(self._callbacks)
-
-                # Add any timeouts that have come due to the callback list.
-                # Do not run anything until we have determined which ones
-                # are ready, so timeouts that call add_timeout cannot
-                # schedule anything in this iteration.
-                due_timeouts = []
-                if self._timeouts:
-                    now = self.time()
-                    while self._timeouts:
-                        if self._timeouts[0].callback is None:
-                            # The timeout was cancelled.  Note that the
-                            # cancellation check is repeated below for timeouts
-                            # that are cancelled by another timeout or callback.
-                            heapq.heappop(self._timeouts)
-                            self._cancellations -= 1
-                        elif self._timeouts[0].deadline <= now:
-                            due_timeouts.append(heapq.heappop(self._timeouts))
-                        else:
-                            break
-                    if (self._cancellations > 512 and
-                            self._cancellations > (len(self._timeouts) >> 1)):
-                        # Clean up the timeout queue when it gets large and it's
-                        # more than half cancellations.
-                        self._cancellations = 0
-                        self._timeouts = [x for x in self._timeouts
-                                          if x.callback is not None]
-                        heapq.heapify(self._timeouts)
-
-                for i in range(ncallbacks):
-                    self._run_callback(self._callbacks.popleft())
-                for timeout in due_timeouts:
-                    if timeout.callback is not None:
-                        self._run_callback(timeout.callback)
-                # Closures may be holding on to a lot of memory, so allow
-                # them to be freed before we go into our poll wait.
-                due_timeouts = timeout = None
-
-                if self._callbacks:
-                    # If any callbacks or timeouts called add_callback,
-                    # we don't want to wait in poll() before we run them.
-                    poll_timeout = 0.0
-                elif self._timeouts:
-                    # If there are any timeouts, schedule the first one.
-                    # Use self.time() instead of 'now' to account for time
-                    # spent running callbacks.
-                    poll_timeout = self._timeouts[0].deadline - self.time()
-                    poll_timeout = max(0, min(poll_timeout, _POLL_TIMEOUT))
-                else:
-                    # No timeouts and no callbacks, so use the default.
-                    poll_timeout = _POLL_TIMEOUT
-
-                if not self._running:
-                    break
-
-                if self._blocking_signal_threshold is not None:
-                    # clear alarm so it doesn't fire while poll is waiting for
-                    # events.
-                    signal.setitimer(signal.ITIMER_REAL, 0, 0)
-
-                try:
-                    event_pairs = self._impl.poll(poll_timeout)
-                except Exception as e:
-                    # Depending on python version and IOLoop implementation,
-                    # different exception types may be thrown and there are
-                    # two ways EINTR might be signaled:
-                    # * e.errno == errno.EINTR
-                    # * e.args is like (errno.EINTR, 'Interrupted system call')
-                    if errno_from_exception(e) == errno.EINTR:
-                        continue
-                    else:
-                        raise
-
-                if self._blocking_signal_threshold is not None:
-                    signal.setitimer(signal.ITIMER_REAL,
-                                     self._blocking_signal_threshold, 0)
-
-                # Pop one fd at a time from the set of pending fds and run
-                # its handler. Since that handler may perform actions on
-                # other file descriptors, there may be reentrant calls to
-                # this IOLoop that modify self._events
-                self._events.update(event_pairs)
-                while self._events:
-                    fd, events = self._events.popitem()
-                    try:
-                        fd_obj, handler_func = self._handlers[fd]
-                        handler_func(fd_obj, events)
-                    except (OSError, IOError) as e:
-                        if errno_from_exception(e) == errno.EPIPE:
-                            # Happens when the client closes the connection
-                            pass
-                        else:
-                            self.handle_callback_exception(self._handlers.get(fd))
-                    except Exception:
-                        self.handle_callback_exception(self._handlers.get(fd))
-                fd_obj = handler_func = None
-
-        finally:
-            # reset the stopped flag so another start/stop pair can be issued
-            self._stopped = False
-            if self._blocking_signal_threshold is not None:
-                signal.setitimer(signal.ITIMER_REAL, 0, 0)
-            IOLoop._current.instance = old_current
-            if old_wakeup_fd is not None:
-                signal.set_wakeup_fd(old_wakeup_fd)
-
-    def stop(self):
-        self._running = False
-        self._stopped = True
-        self._waker.wake()
-
-    def time(self):
-        return self.time_func()
-
-    def call_at(self, deadline, callback, *args, **kwargs):
-        timeout = _Timeout(
-            deadline,
-            functools.partial(stack_context.wrap(callback), *args, **kwargs),
-            self)
-        heapq.heappush(self._timeouts, timeout)
-        return timeout
-
-    def remove_timeout(self, timeout):
-        # Removing from a heap is complicated, so just leave the defunct
-        # timeout object in the queue (see discussion in
-        # http://docs.python.org/library/heapq.html).
-        # If this turns out to be a problem, we could add a garbage
-        # collection pass whenever there are too many dead timeouts.
-        timeout.callback = None
-        self._cancellations += 1
-
-    def add_callback(self, callback, *args, **kwargs):
-        if self._closing:
-            return
-        # Blindly insert into self._callbacks. This is safe even
-        # from signal handlers because deque.append is atomic.
-        self._callbacks.append(functools.partial(
-            stack_context.wrap(callback), *args, **kwargs))
-        if thread.get_ident() != self._thread_ident:
-            # This will write one byte but Waker.consume() reads many
-            # at once, so it's ok to write even when not strictly
-            # necessary.
-            self._waker.wake()
-        else:
-            # If we're on the IOLoop's thread, we don't need to wake anyone.
-            pass
-
-    def add_callback_from_signal(self, callback, *args, **kwargs):
-        with stack_context.NullContext():
-            self.add_callback(callback, *args, **kwargs)
-
-
-class _Timeout(object):
-    """An IOLoop timeout, a UNIX timestamp and a callback"""
-
-    # Reduce memory overhead when there are lots of pending callbacks
-    __slots__ = ['deadline', 'callback', 'tdeadline']
-
-    def __init__(self, deadline, callback, io_loop):
-        if not isinstance(deadline, numbers.Real):
-            raise TypeError("Unsupported deadline %r" % deadline)
-        self.deadline = deadline
-        self.callback = callback
-        self.tdeadline = (deadline, next(io_loop._timeout_counter))
-
-    # Comparison methods to sort by deadline, with object id as a tiebreaker
-    # to guarantee a consistent ordering.  The heapq module uses __le__
-    # in python2.5, and __lt__ in 2.6+ (sort() and most other comparisons
-    # use __lt__).
-    def __lt__(self, other):
-        return self.tdeadline < other.tdeadline
-
-    def __le__(self, other):
-        return self.tdeadline <= other.tdeadline
-
-
-class PeriodicCallback(object):
-    """Schedules the given callback to be called periodically.
-
-    The callback is called every ``callback_time`` milliseconds.
-    Note that the timeout is given in milliseconds, while most other
-    time-related functions in Tornado use seconds.
-
-    If the callback runs for longer than ``callback_time`` milliseconds,
-    subsequent invocations will be skipped to get back on schedule.
-
-    `start` must be called after the `PeriodicCallback` is created.
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-    """
-    def __init__(self, callback, callback_time, io_loop=None):
-        self.callback = callback
-        if callback_time <= 0:
-            raise ValueError("Periodic callback must have a positive callback_time")
-        self.callback_time = callback_time
-        self.io_loop = io_loop or IOLoop.current()
-        self._running = False
-        self._timeout = None
-
-    def start(self):
-        """Starts the timer."""
-        self._running = True
-        self._next_timeout = self.io_loop.time()
-        self._schedule_next()
-
-    def stop(self):
-        """Stops the timer."""
-        self._running = False
-        if self._timeout is not None:
-            self.io_loop.remove_timeout(self._timeout)
-            self._timeout = None
-
-    def is_running(self):
-        """Return True if this `.PeriodicCallback` has been started.
-
-        .. versionadded:: 4.1
-        """
-        return self._running
-
-    def _run(self):
-        if not self._running:
-            return
-        try:
-            return self.callback()
-        except Exception:
-            self.io_loop.handle_callback_exception(self.callback)
-        finally:
-            self._schedule_next()
-
-    def _schedule_next(self):
-        if self._running:
-            current_time = self.io_loop.time()
-
-            if self._next_timeout <= current_time:
-                callback_time_sec = self.callback_time / 1000.0
-                self._next_timeout += (math.floor((current_time - self._next_timeout) /
-                                                  callback_time_sec) + 1) * callback_time_sec
-
-            self._timeout = self.io_loop.add_timeout(self._next_timeout, self._run)
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""An I/O event loop for non-blocking sockets. 
+ 
+Typical applications will use a single `IOLoop` object, in the 
+`IOLoop.instance` singleton.  The `IOLoop.start` method should usually 
+be called at the end of the ``main()`` function.  Atypical applications may 
+use more than one `IOLoop`, such as one `IOLoop` per thread, or per `unittest` 
+case. 
+ 
+In addition to I/O events, the `IOLoop` can also schedule time-based events. 
+`IOLoop.add_timeout` is a non-blocking alternative to `time.sleep`. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import collections 
+import datetime 
+import errno 
+import functools 
+import heapq 
+import itertools 
+import logging 
+import numbers 
+import os 
+import select 
+import sys 
+import threading 
+import time 
+import traceback 
+import math 
+ 
+from tornado.concurrent import TracebackFuture, is_future 
+from tornado.log import app_log, gen_log 
+from tornado.platform.auto import set_close_exec, Waker 
+from tornado import stack_context 
+from tornado.util import PY3, Configurable, errno_from_exception, timedelta_to_seconds 
+ 
+try: 
+    import signal 
+except ImportError: 
+    signal = None 
+ 
+ 
+if PY3: 
+    import _thread as thread 
+else: 
+    import thread 
+ 
+ 
+_POLL_TIMEOUT = 3600.0 
+ 
+ 
+class TimeoutError(Exception): 
+    pass 
+ 
+ 
+class IOLoop(Configurable): 
+    """A level-triggered I/O loop. 
+ 
+    We use ``epoll`` (Linux) or ``kqueue`` (BSD and Mac OS X) if they 
+    are available, or else we fall back on select(). If you are 
+    implementing a system that needs to handle thousands of 
+    simultaneous connections, you should use a system that supports 
+    either ``epoll`` or ``kqueue``. 
+ 
+    Example usage for a simple TCP server: 
+ 
+    .. testcode:: 
+ 
+        import errno 
+        import functools 
+        import tornado.ioloop 
+        import socket 
+ 
+        def connection_ready(sock, fd, events): 
+            while True: 
+                try: 
+                    connection, address = sock.accept() 
+                except socket.error as e: 
+                    if e.args[0] not in (errno.EWOULDBLOCK, errno.EAGAIN): 
+                        raise 
+                    return 
+                connection.setblocking(0) 
+                handle_connection(connection, address) 
+ 
+        if __name__ == '__main__': 
+            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) 
+            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) 
+            sock.setblocking(0) 
+            sock.bind(("", port)) 
+            sock.listen(128) 
+ 
+            io_loop = tornado.ioloop.IOLoop.current() 
+            callback = functools.partial(connection_ready, sock) 
+            io_loop.add_handler(sock.fileno(), callback, io_loop.READ) 
+            io_loop.start() 
+ 
+    .. testoutput:: 
+       :hide: 
+ 
+    By default, a newly-constructed `IOLoop` becomes the thread's current 
+    `IOLoop`, unless there already is a current `IOLoop`. This behavior 
+    can be controlled with the ``make_current`` argument to the `IOLoop` 
+    constructor: if ``make_current=True``, the new `IOLoop` will always 
+    try to become current and it raises an error if there is already a 
+    current instance. If ``make_current=False``, the new `IOLoop` will 
+    not try to become current. 
+ 
+    .. versionchanged:: 4.2 
+       Added the ``make_current`` keyword argument to the `IOLoop` 
+       constructor. 
+    """ 
+    # Constants from the epoll module 
+    _EPOLLIN = 0x001 
+    _EPOLLPRI = 0x002 
+    _EPOLLOUT = 0x004 
+    _EPOLLERR = 0x008 
+    _EPOLLHUP = 0x010 
+    _EPOLLRDHUP = 0x2000 
+    _EPOLLONESHOT = (1 << 30) 
+    _EPOLLET = (1 << 31) 
+ 
+    # Our events map exactly to the epoll events 
+    NONE = 0 
+    READ = _EPOLLIN 
+    WRITE = _EPOLLOUT 
+    ERROR = _EPOLLERR | _EPOLLHUP 
+ 
+    # Global lock for creating global IOLoop instance 
+    _instance_lock = threading.Lock() 
+ 
+    _current = threading.local() 
+ 
+    @staticmethod 
+    def instance(): 
+        """Returns a global `IOLoop` instance. 
+ 
+        Most applications have a single, global `IOLoop` running on the 
+        main thread.  Use this method to get this instance from 
+        another thread.  In most other cases, it is better to use `current()` 
+        to get the current thread's `IOLoop`. 
+        """ 
+        if not hasattr(IOLoop, "_instance"): 
+            with IOLoop._instance_lock: 
+                if not hasattr(IOLoop, "_instance"): 
+                    # New instance after double check 
+                    IOLoop._instance = IOLoop() 
+        return IOLoop._instance 
+ 
+    @staticmethod 
+    def initialized(): 
+        """Returns true if the singleton instance has been created.""" 
+        return hasattr(IOLoop, "_instance") 
+ 
+    def install(self): 
+        """Installs this `IOLoop` object as the singleton instance. 
+ 
+        This is normally not necessary as `instance()` will create 
+        an `IOLoop` on demand, but you may want to call `install` to use 
+        a custom subclass of `IOLoop`. 
+ 
+        When using an `IOLoop` subclass, `install` must be called prior 
+        to creating any objects that implicitly create their own 
+        `IOLoop` (e.g., :class:`tornado.httpclient.AsyncHTTPClient`). 
+        """ 
+        assert not IOLoop.initialized() 
+        IOLoop._instance = self 
+ 
+    @staticmethod 
+    def clear_instance(): 
+        """Clear the global `IOLoop` instance. 
+ 
+        .. versionadded:: 4.0 
+        """ 
+        if hasattr(IOLoop, "_instance"): 
+            del IOLoop._instance 
+ 
+    @staticmethod 
+    def current(instance=True): 
+        """Returns the current thread's `IOLoop`. 
+ 
+        If an `IOLoop` is currently running or has been marked as 
+        current by `make_current`, returns that instance.  If there is 
+        no current `IOLoop`, returns `IOLoop.instance()` (i.e. the 
+        main thread's `IOLoop`, creating one if necessary) if ``instance`` 
+        is true. 
+ 
+        In general you should use `IOLoop.current` as the default when 
+        constructing an asynchronous object, and use `IOLoop.instance` 
+        when you mean to communicate to the main thread from a different 
+        one. 
+ 
+        .. versionchanged:: 4.1 
+           Added ``instance`` argument to control the fallback to 
+           `IOLoop.instance()`. 
+        """ 
+        current = getattr(IOLoop._current, "instance", None) 
+        if current is None and instance: 
+            return IOLoop.instance() 
+        return current 
+ 
+    def make_current(self): 
+        """Makes this the `IOLoop` for the current thread. 
+ 
+        An `IOLoop` automatically becomes current for its thread 
+        when it is started, but it is sometimes useful to call 
+        `make_current` explicitly before starting the `IOLoop`, 
+        so that code run at startup time can find the right 
+        instance. 
+ 
+        .. versionchanged:: 4.1 
+           An `IOLoop` created while there is no current `IOLoop` 
+           will automatically become current. 
+        """ 
+        IOLoop._current.instance = self 
+ 
+    @staticmethod 
+    def clear_current(): 
+        IOLoop._current.instance = None 
+ 
+    @classmethod 
+    def configurable_base(cls): 
+        return IOLoop 
+ 
+    @classmethod 
+    def configurable_default(cls): 
+        if hasattr(select, "epoll"): 
+            from tornado.platform.epoll import EPollIOLoop 
+            return EPollIOLoop 
+        if hasattr(select, "kqueue"): 
+            # Python 2.6+ on BSD or Mac 
+            from tornado.platform.kqueue import KQueueIOLoop 
+            return KQueueIOLoop 
+        from tornado.platform.select import SelectIOLoop 
+        return SelectIOLoop 
+ 
+    def initialize(self, make_current=None): 
+        if make_current is None: 
+            if IOLoop.current(instance=False) is None: 
+                self.make_current() 
+        elif make_current: 
+            if IOLoop.current(instance=False) is not None: 
+                raise RuntimeError("current IOLoop already exists") 
+            self.make_current() 
+ 
+    def close(self, all_fds=False): 
+        """Closes the `IOLoop`, freeing any resources used. 
+ 
+        If ``all_fds`` is true, all file descriptors registered on the 
+        IOLoop will be closed (not just the ones created by the 
+        `IOLoop` itself). 
+ 
+        Many applications will only use a single `IOLoop` that runs for the 
+        entire lifetime of the process.  In that case closing the `IOLoop` 
+        is not necessary since everything will be cleaned up when the 
+        process exits.  `IOLoop.close` is provided mainly for scenarios 
+        such as unit tests, which create and destroy a large number of 
+        ``IOLoops``. 
+ 
+        An `IOLoop` must be completely stopped before it can be closed.  This 
+        means that `IOLoop.stop()` must be called *and* `IOLoop.start()` must 
+        be allowed to return before attempting to call `IOLoop.close()`. 
+        Therefore the call to `close` will usually appear just after 
+        the call to `start` rather than near the call to `stop`. 
+ 
+        .. versionchanged:: 3.1 
+           If the `IOLoop` implementation supports non-integer objects 
+           for "file descriptors", those objects will have their 
+           ``close`` method when ``all_fds`` is true. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def add_handler(self, fd, handler, events): 
+        """Registers the given handler to receive the given events for ``fd``. 
+ 
+        The ``fd`` argument may either be an integer file descriptor or 
+        a file-like object with a ``fileno()`` method (and optionally a 
+        ``close()`` method, which may be called when the `IOLoop` is shut 
+        down). 
+ 
+        The ``events`` argument is a bitwise or of the constants 
+        ``IOLoop.READ``, ``IOLoop.WRITE``, and ``IOLoop.ERROR``. 
+ 
+        When an event occurs, ``handler(fd, events)`` will be run. 
+ 
+        .. versionchanged:: 4.0 
+           Added the ability to pass file-like objects in addition to 
+           raw file descriptors. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def update_handler(self, fd, events): 
+        """Changes the events we listen for ``fd``. 
+ 
+        .. versionchanged:: 4.0 
+           Added the ability to pass file-like objects in addition to 
+           raw file descriptors. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def remove_handler(self, fd): 
+        """Stop listening for events on ``fd``. 
+ 
+        .. versionchanged:: 4.0 
+           Added the ability to pass file-like objects in addition to 
+           raw file descriptors. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def set_blocking_signal_threshold(self, seconds, action): 
+        """Sends a signal if the `IOLoop` is blocked for more than 
+        ``s`` seconds. 
+ 
+        Pass ``seconds=None`` to disable.  Requires Python 2.6 on a unixy 
+        platform. 
+ 
+        The action parameter is a Python signal handler.  Read the 
+        documentation for the `signal` module for more information. 
+        If ``action`` is None, the process will be killed if it is 
+        blocked for too long. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def set_blocking_log_threshold(self, seconds): 
+        """Logs a stack trace if the `IOLoop` is blocked for more than 
+        ``s`` seconds. 
+ 
+        Equivalent to ``set_blocking_signal_threshold(seconds, 
+        self.log_stack)`` 
+        """ 
+        self.set_blocking_signal_threshold(seconds, self.log_stack) 
+ 
+    def log_stack(self, signal, frame): 
+        """Signal handler to log the stack trace of the current thread. 
+ 
+        For use with `set_blocking_signal_threshold`. 
+        """ 
+        gen_log.warning('IOLoop blocked for %f seconds in\n%s', 
+                        self._blocking_signal_threshold, 
+                        ''.join(traceback.format_stack(frame))) 
+ 
+    def start(self): 
+        """Starts the I/O loop. 
+ 
+        The loop will run until one of the callbacks calls `stop()`, which 
+        will make the loop stop after the current event iteration completes. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def _setup_logging(self): 
+        """The IOLoop catches and logs exceptions, so it's 
+        important that log output be visible.  However, python's 
+        default behavior for non-root loggers (prior to python 
+        3.2) is to print an unhelpful "no handlers could be 
+        found" message rather than the actual log entry, so we 
+        must explicitly configure logging if we've made it this 
+        far without anything. 
+ 
+        This method should be called from start() in subclasses. 
+        """ 
+        if not any([logging.getLogger().handlers, 
+                    logging.getLogger('tornado').handlers, 
+                    logging.getLogger('tornado.application').handlers]): 
+            logging.basicConfig() 
+ 
+    def stop(self): 
+        """Stop the I/O loop. 
+ 
+        If the event loop is not currently running, the next call to `start()` 
+        will return immediately. 
+ 
+        To use asynchronous methods from otherwise-synchronous code (such as 
+        unit tests), you can start and stop the event loop like this:: 
+ 
+          ioloop = IOLoop() 
+          async_method(ioloop=ioloop, callback=ioloop.stop) 
+          ioloop.start() 
+ 
+        ``ioloop.start()`` will return after ``async_method`` has run 
+        its callback, whether that callback was invoked before or 
+        after ``ioloop.start``. 
+ 
+        Note that even after `stop` has been called, the `IOLoop` is not 
+        completely stopped until `IOLoop.start` has also returned. 
+        Some work that was scheduled before the call to `stop` may still 
+        be run before the `IOLoop` shuts down. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def run_sync(self, func, timeout=None): 
+        """Starts the `IOLoop`, runs the given function, and stops the loop. 
+ 
+        The function must return either a yieldable object or 
+        ``None``. If the function returns a yieldable object, the 
+        `IOLoop` will run until the yieldable is resolved (and 
+        `run_sync()` will return the yieldable's result). If it raises 
+        an exception, the `IOLoop` will stop and the exception will be 
+        re-raised to the caller. 
+ 
+        The keyword-only argument ``timeout`` may be used to set 
+        a maximum duration for the function.  If the timeout expires, 
+        a `TimeoutError` is raised. 
+ 
+        This method is useful in conjunction with `tornado.gen.coroutine` 
+        to allow asynchronous calls in a ``main()`` function:: 
+ 
+            @gen.coroutine 
+            def main(): 
+                # do stuff... 
+ 
+            if __name__ == '__main__': 
+                IOLoop.current().run_sync(main) 
+ 
+        .. versionchanged:: 4.3 
+           Returning a non-``None``, non-yieldable value is now an error. 
+        """ 
+        future_cell = [None] 
+ 
+        def run(): 
+            try: 
+                result = func() 
+                if result is not None: 
+                    from tornado.gen import convert_yielded 
+                    result = convert_yielded(result) 
+            except Exception: 
+                future_cell[0] = TracebackFuture() 
+                future_cell[0].set_exc_info(sys.exc_info()) 
+            else: 
+                if is_future(result): 
+                    future_cell[0] = result 
+                else: 
+                    future_cell[0] = TracebackFuture() 
+                    future_cell[0].set_result(result) 
+            self.add_future(future_cell[0], lambda future: self.stop()) 
+        self.add_callback(run) 
+        if timeout is not None: 
+            timeout_handle = self.add_timeout(self.time() + timeout, self.stop) 
+        self.start() 
+        if timeout is not None: 
+            self.remove_timeout(timeout_handle) 
+        if not future_cell[0].done(): 
+            raise TimeoutError('Operation timed out after %s seconds' % timeout) 
+        return future_cell[0].result() 
+ 
+    def time(self): 
+        """Returns the current time according to the `IOLoop`'s clock. 
+ 
+        The return value is a floating-point number relative to an 
+        unspecified time in the past. 
+ 
+        By default, the `IOLoop`'s time function is `time.time`.  However, 
+        it may be configured to use e.g. `time.monotonic` instead. 
+        Calls to `add_timeout` that pass a number instead of a 
+        `datetime.timedelta` should use this function to compute the 
+        appropriate time, so they can work no matter what time function 
+        is chosen. 
+        """ 
+        return time.time() 
+ 
+    def add_timeout(self, deadline, callback, *args, **kwargs): 
+        """Runs the ``callback`` at the time ``deadline`` from the I/O loop. 
+ 
+        Returns an opaque handle that may be passed to 
+        `remove_timeout` to cancel. 
+ 
+        ``deadline`` may be a number denoting a time (on the same 
+        scale as `IOLoop.time`, normally `time.time`), or a 
+        `datetime.timedelta` object for a deadline relative to the 
+        current time.  Since Tornado 4.0, `call_later` is a more 
+        convenient alternative for the relative case since it does not 
+        require a timedelta object. 
+ 
+        Note that it is not safe to call `add_timeout` from other threads. 
+        Instead, you must use `add_callback` to transfer control to the 
+        `IOLoop`'s thread, and then call `add_timeout` from there. 
+ 
+        Subclasses of IOLoop must implement either `add_timeout` or 
+        `call_at`; the default implementations of each will call 
+        the other.  `call_at` is usually easier to implement, but 
+        subclasses that wish to maintain compatibility with Tornado 
+        versions prior to 4.0 must use `add_timeout` instead. 
+ 
+        .. versionchanged:: 4.0 
+           Now passes through ``*args`` and ``**kwargs`` to the callback. 
+        """ 
+        if isinstance(deadline, numbers.Real): 
+            return self.call_at(deadline, callback, *args, **kwargs) 
+        elif isinstance(deadline, datetime.timedelta): 
+            return self.call_at(self.time() + timedelta_to_seconds(deadline), 
+                                callback, *args, **kwargs) 
+        else: 
+            raise TypeError("Unsupported deadline %r" % deadline) 
+ 
+    def call_later(self, delay, callback, *args, **kwargs): 
+        """Runs the ``callback`` after ``delay`` seconds have passed. 
+ 
+        Returns an opaque handle that may be passed to `remove_timeout` 
+        to cancel.  Note that unlike the `asyncio` method of the same 
+        name, the returned object does not have a ``cancel()`` method. 
+ 
+        See `add_timeout` for comments on thread-safety and subclassing. 
+ 
+        .. versionadded:: 4.0 
+        """ 
+        return self.call_at(self.time() + delay, callback, *args, **kwargs) 
+ 
+    def call_at(self, when, callback, *args, **kwargs): 
+        """Runs the ``callback`` at the absolute time designated by ``when``. 
+ 
+        ``when`` must be a number using the same reference point as 
+        `IOLoop.time`. 
+ 
+        Returns an opaque handle that may be passed to `remove_timeout` 
+        to cancel.  Note that unlike the `asyncio` method of the same 
+        name, the returned object does not have a ``cancel()`` method. 
+ 
+        See `add_timeout` for comments on thread-safety and subclassing. 
+ 
+        .. versionadded:: 4.0 
+        """ 
+        return self.add_timeout(when, callback, *args, **kwargs) 
+ 
+    def remove_timeout(self, timeout): 
+        """Cancels a pending timeout. 
+ 
+        The argument is a handle as returned by `add_timeout`.  It is 
+        safe to call `remove_timeout` even if the callback has already 
+        been run. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def add_callback(self, callback, *args, **kwargs): 
+        """Calls the given callback on the next I/O loop iteration. 
+ 
+        It is safe to call this method from any thread at any time, 
+        except from a signal handler.  Note that this is the **only** 
+        method in `IOLoop` that makes this thread-safety guarantee; all 
+        other interaction with the `IOLoop` must be done from that 
+        `IOLoop`'s thread.  `add_callback()` may be used to transfer 
+        control from other threads to the `IOLoop`'s thread. 
+ 
+        To add a callback from a signal handler, see 
+        `add_callback_from_signal`. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def add_callback_from_signal(self, callback, *args, **kwargs): 
+        """Calls the given callback on the next I/O loop iteration. 
+ 
+        Safe for use from a Python signal handler; should not be used 
+        otherwise. 
+ 
+        Callbacks added with this method will be run without any 
+        `.stack_context`, to avoid picking up the context of the function 
+        that was interrupted by the signal. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def spawn_callback(self, callback, *args, **kwargs): 
+        """Calls the given callback on the next IOLoop iteration. 
+ 
+        Unlike all other callback-related methods on IOLoop, 
+        ``spawn_callback`` does not associate the callback with its caller's 
+        ``stack_context``, so it is suitable for fire-and-forget callbacks 
+        that should not interfere with the caller. 
+ 
+        .. versionadded:: 4.0 
+        """ 
+        with stack_context.NullContext(): 
+            self.add_callback(callback, *args, **kwargs) 
+ 
+    def add_future(self, future, callback): 
+        """Schedules a callback on the ``IOLoop`` when the given 
+        `.Future` is finished. 
+ 
+        The callback is invoked with one argument, the 
+        `.Future`. 
+        """ 
+        assert is_future(future) 
+        callback = stack_context.wrap(callback) 
+        future.add_done_callback( 
+            lambda future: self.add_callback(callback, future)) 
+ 
+    def _run_callback(self, callback): 
+        """Runs a callback with error handling. 
+ 
+        For use in subclasses. 
+        """ 
+        try: 
+            ret = callback() 
+            if ret is not None: 
+                from tornado import gen 
+                # Functions that return Futures typically swallow all 
+                # exceptions and store them in the Future.  If a Future 
+                # makes it out to the IOLoop, ensure its exception (if any) 
+                # gets logged too. 
+                try: 
+                    ret = gen.convert_yielded(ret) 
+                except gen.BadYieldError: 
+                    # It's not unusual for add_callback to be used with 
+                    # methods returning a non-None and non-yieldable 
+                    # result, which should just be ignored. 
+                    pass 
+                else: 
+                    self.add_future(ret, self._discard_future_result) 
+        except Exception: 
+            self.handle_callback_exception(callback) 
+ 
+    def _discard_future_result(self, future): 
+        """Avoid unhandled-exception warnings from spawned coroutines.""" 
+        future.result() 
+ 
+    def handle_callback_exception(self, callback): 
+        """This method is called whenever a callback run by the `IOLoop` 
+        throws an exception. 
+ 
+        By default simply logs the exception as an error.  Subclasses 
+        may override this method to customize reporting of exceptions. 
+ 
+        The exception itself is not passed explicitly, but is available 
+        in `sys.exc_info`. 
+        """ 
+        app_log.error("Exception in callback %r", callback, exc_info=True) 
+ 
+    def split_fd(self, fd): 
+        """Returns an (fd, obj) pair from an ``fd`` parameter. 
+ 
+        We accept both raw file descriptors and file-like objects as 
+        input to `add_handler` and related methods.  When a file-like 
+        object is passed, we must retain the object itself so we can 
+        close it correctly when the `IOLoop` shuts down, but the 
+        poller interfaces favor file descriptors (they will accept 
+        file-like objects and call ``fileno()`` for you, but they 
+        always return the descriptor itself). 
+ 
+        This method is provided for use by `IOLoop` subclasses and should 
+        not generally be used by application code. 
+ 
+        .. versionadded:: 4.0 
+        """ 
+        try: 
+            return fd.fileno(), fd 
+        except AttributeError: 
+            return fd, fd 
+ 
+    def close_fd(self, fd): 
+        """Utility method to close an ``fd``. 
+ 
+        If ``fd`` is a file-like object, we close it directly; otherwise 
+        we use `os.close`. 
+ 
+        This method is provided for use by `IOLoop` subclasses (in 
+        implementations of ``IOLoop.close(all_fds=True)`` and should 
+        not generally be used by application code. 
+ 
+        .. versionadded:: 4.0 
+        """ 
+        try: 
+            try: 
+                fd.close() 
+            except AttributeError: 
+                os.close(fd) 
+        except OSError: 
+            pass 
+ 
+ 
+class PollIOLoop(IOLoop): 
+    """Base class for IOLoops built around a select-like function. 
+ 
+    For concrete implementations, see `tornado.platform.epoll.EPollIOLoop` 
+    (Linux), `tornado.platform.kqueue.KQueueIOLoop` (BSD and Mac), or 
+    `tornado.platform.select.SelectIOLoop` (all platforms). 
+    """ 
+    def initialize(self, impl, time_func=None, **kwargs): 
+        super(PollIOLoop, self).initialize(**kwargs) 
+        self._impl = impl 
+        if hasattr(self._impl, 'fileno'): 
+            set_close_exec(self._impl.fileno()) 
+        self.time_func = time_func or time.time 
+        self._handlers = {} 
+        self._events = {} 
+        self._callbacks = collections.deque() 
+        self._timeouts = [] 
+        self._cancellations = 0 
+        self._running = False 
+        self._stopped = False 
+        self._closing = False 
+        self._thread_ident = None 
+        self._blocking_signal_threshold = None 
+        self._timeout_counter = itertools.count() 
+ 
+        # Create a pipe that we send bogus data to when we want to wake 
+        # the I/O loop when it is idle 
+        self._waker = Waker() 
+        self.add_handler(self._waker.fileno(), 
+                         lambda fd, events: self._waker.consume(), 
+                         self.READ) 
+ 
+    def close(self, all_fds=False): 
+        self._closing = True 
+        self.remove_handler(self._waker.fileno()) 
+        if all_fds: 
+            for fd, handler in list(self._handlers.values()): 
+                self.close_fd(fd) 
+        self._waker.close() 
+        self._impl.close() 
+        self._callbacks = None 
+        self._timeouts = None 
+ 
+    def add_handler(self, fd, handler, events): 
+        fd, obj = self.split_fd(fd) 
+        self._handlers[fd] = (obj, stack_context.wrap(handler)) 
+        self._impl.register(fd, events | self.ERROR) 
+ 
+    def update_handler(self, fd, events): 
+        fd, obj = self.split_fd(fd) 
+        self._impl.modify(fd, events | self.ERROR) 
+ 
+    def remove_handler(self, fd): 
+        fd, obj = self.split_fd(fd) 
+        self._handlers.pop(fd, None) 
+        self._events.pop(fd, None) 
+        try: 
+            self._impl.unregister(fd) 
+        except Exception: 
+            gen_log.debug("Error deleting fd from IOLoop", exc_info=True) 
+ 
+    def set_blocking_signal_threshold(self, seconds, action): 
+        if not hasattr(signal, "setitimer"): 
+            gen_log.error("set_blocking_signal_threshold requires a signal module " 
+                          "with the setitimer method") 
+            return 
+        self._blocking_signal_threshold = seconds 
+        if seconds is not None: 
+            signal.signal(signal.SIGALRM, 
+                          action if action is not None else signal.SIG_DFL) 
+ 
+    def start(self): 
+        if self._running: 
+            raise RuntimeError("IOLoop is already running") 
+        self._setup_logging() 
+        if self._stopped: 
+            self._stopped = False 
+            return 
+        old_current = getattr(IOLoop._current, "instance", None) 
+        IOLoop._current.instance = self 
+        self._thread_ident = thread.get_ident() 
+        self._running = True 
+ 
+        # signal.set_wakeup_fd closes a race condition in event loops: 
+        # a signal may arrive at the beginning of select/poll/etc 
+        # before it goes into its interruptible sleep, so the signal 
+        # will be consumed without waking the select.  The solution is 
+        # for the (C, synchronous) signal handler to write to a pipe, 
+        # which will then be seen by select. 
+        # 
+        # In python's signal handling semantics, this only matters on the 
+        # main thread (fortunately, set_wakeup_fd only works on the main 
+        # thread and will raise a ValueError otherwise). 
+        # 
+        # If someone has already set a wakeup fd, we don't want to 
+        # disturb it.  This is an issue for twisted, which does its 
+        # SIGCHLD processing in response to its own wakeup fd being 
+        # written to.  As long as the wakeup fd is registered on the IOLoop, 
+        # the loop will still wake up and everything should work. 
+        old_wakeup_fd = None 
+        if hasattr(signal, 'set_wakeup_fd') and os.name == 'posix': 
+            # requires python 2.6+, unix.  set_wakeup_fd exists but crashes 
+            # the python process on windows. 
+            try: 
+                old_wakeup_fd = signal.set_wakeup_fd(self._waker.write_fileno()) 
+                if old_wakeup_fd != -1: 
+                    # Already set, restore previous value.  This is a little racy, 
+                    # but there's no clean get_wakeup_fd and in real use the 
+                    # IOLoop is just started once at the beginning. 
+                    signal.set_wakeup_fd(old_wakeup_fd) 
+                    old_wakeup_fd = None 
+            except ValueError: 
+                # Non-main thread, or the previous value of wakeup_fd 
+                # is no longer valid. 
+                old_wakeup_fd = None 
+ 
+        try: 
+            while True: 
+                # Prevent IO event starvation by delaying new callbacks 
+                # to the next iteration of the event loop. 
+                ncallbacks = len(self._callbacks) 
+ 
+                # Add any timeouts that have come due to the callback list. 
+                # Do not run anything until we have determined which ones 
+                # are ready, so timeouts that call add_timeout cannot 
+                # schedule anything in this iteration. 
+                due_timeouts = [] 
+                if self._timeouts: 
+                    now = self.time() 
+                    while self._timeouts: 
+                        if self._timeouts[0].callback is None: 
+                            # The timeout was cancelled.  Note that the 
+                            # cancellation check is repeated below for timeouts 
+                            # that are cancelled by another timeout or callback. 
+                            heapq.heappop(self._timeouts) 
+                            self._cancellations -= 1 
+                        elif self._timeouts[0].deadline <= now: 
+                            due_timeouts.append(heapq.heappop(self._timeouts)) 
+                        else: 
+                            break 
+                    if (self._cancellations > 512 and 
+                            self._cancellations > (len(self._timeouts) >> 1)): 
+                        # Clean up the timeout queue when it gets large and it's 
+                        # more than half cancellations. 
+                        self._cancellations = 0 
+                        self._timeouts = [x for x in self._timeouts 
+                                          if x.callback is not None] 
+                        heapq.heapify(self._timeouts) 
+ 
+                for i in range(ncallbacks): 
+                    self._run_callback(self._callbacks.popleft()) 
+                for timeout in due_timeouts: 
+                    if timeout.callback is not None: 
+                        self._run_callback(timeout.callback) 
+                # Closures may be holding on to a lot of memory, so allow 
+                # them to be freed before we go into our poll wait. 
+                due_timeouts = timeout = None 
+ 
+                if self._callbacks: 
+                    # If any callbacks or timeouts called add_callback, 
+                    # we don't want to wait in poll() before we run them. 
+                    poll_timeout = 0.0 
+                elif self._timeouts: 
+                    # If there are any timeouts, schedule the first one. 
+                    # Use self.time() instead of 'now' to account for time 
+                    # spent running callbacks. 
+                    poll_timeout = self._timeouts[0].deadline - self.time() 
+                    poll_timeout = max(0, min(poll_timeout, _POLL_TIMEOUT)) 
+                else: 
+                    # No timeouts and no callbacks, so use the default. 
+                    poll_timeout = _POLL_TIMEOUT 
+ 
+                if not self._running: 
+                    break 
+ 
+                if self._blocking_signal_threshold is not None: 
+                    # clear alarm so it doesn't fire while poll is waiting for 
+                    # events. 
+                    signal.setitimer(signal.ITIMER_REAL, 0, 0) 
+ 
+                try: 
+                    event_pairs = self._impl.poll(poll_timeout) 
+                except Exception as e: 
+                    # Depending on python version and IOLoop implementation, 
+                    # different exception types may be thrown and there are 
+                    # two ways EINTR might be signaled: 
+                    # * e.errno == errno.EINTR 
+                    # * e.args is like (errno.EINTR, 'Interrupted system call') 
+                    if errno_from_exception(e) == errno.EINTR: 
+                        continue 
+                    else: 
+                        raise 
+ 
+                if self._blocking_signal_threshold is not None: 
+                    signal.setitimer(signal.ITIMER_REAL, 
+                                     self._blocking_signal_threshold, 0) 
+ 
+                # Pop one fd at a time from the set of pending fds and run 
+                # its handler. Since that handler may perform actions on 
+                # other file descriptors, there may be reentrant calls to 
+                # this IOLoop that modify self._events 
+                self._events.update(event_pairs) 
+                while self._events: 
+                    fd, events = self._events.popitem() 
+                    try: 
+                        fd_obj, handler_func = self._handlers[fd] 
+                        handler_func(fd_obj, events) 
+                    except (OSError, IOError) as e: 
+                        if errno_from_exception(e) == errno.EPIPE: 
+                            # Happens when the client closes the connection 
+                            pass 
+                        else: 
+                            self.handle_callback_exception(self._handlers.get(fd)) 
+                    except Exception: 
+                        self.handle_callback_exception(self._handlers.get(fd)) 
+                fd_obj = handler_func = None 
+ 
+        finally: 
+            # reset the stopped flag so another start/stop pair can be issued 
+            self._stopped = False 
+            if self._blocking_signal_threshold is not None: 
+                signal.setitimer(signal.ITIMER_REAL, 0, 0) 
+            IOLoop._current.instance = old_current 
+            if old_wakeup_fd is not None: 
+                signal.set_wakeup_fd(old_wakeup_fd) 
+ 
+    def stop(self): 
+        self._running = False 
+        self._stopped = True 
+        self._waker.wake() 
+ 
+    def time(self): 
+        return self.time_func() 
+ 
+    def call_at(self, deadline, callback, *args, **kwargs): 
+        timeout = _Timeout( 
+            deadline, 
+            functools.partial(stack_context.wrap(callback), *args, **kwargs), 
+            self) 
+        heapq.heappush(self._timeouts, timeout) 
+        return timeout 
+ 
+    def remove_timeout(self, timeout): 
+        # Removing from a heap is complicated, so just leave the defunct 
+        # timeout object in the queue (see discussion in 
+        # http://docs.python.org/library/heapq.html). 
+        # If this turns out to be a problem, we could add a garbage 
+        # collection pass whenever there are too many dead timeouts. 
+        timeout.callback = None 
+        self._cancellations += 1 
+ 
+    def add_callback(self, callback, *args, **kwargs): 
+        if self._closing: 
+            return 
+        # Blindly insert into self._callbacks. This is safe even 
+        # from signal handlers because deque.append is atomic. 
+        self._callbacks.append(functools.partial( 
+            stack_context.wrap(callback), *args, **kwargs)) 
+        if thread.get_ident() != self._thread_ident: 
+            # This will write one byte but Waker.consume() reads many 
+            # at once, so it's ok to write even when not strictly 
+            # necessary. 
+            self._waker.wake() 
+        else: 
+            # If we're on the IOLoop's thread, we don't need to wake anyone. 
+            pass 
+ 
+    def add_callback_from_signal(self, callback, *args, **kwargs): 
+        with stack_context.NullContext(): 
+            self.add_callback(callback, *args, **kwargs) 
+ 
+ 
+class _Timeout(object): 
+    """An IOLoop timeout, a UNIX timestamp and a callback""" 
+ 
+    # Reduce memory overhead when there are lots of pending callbacks 
+    __slots__ = ['deadline', 'callback', 'tdeadline'] 
+ 
+    def __init__(self, deadline, callback, io_loop): 
+        if not isinstance(deadline, numbers.Real): 
+            raise TypeError("Unsupported deadline %r" % deadline) 
+        self.deadline = deadline 
+        self.callback = callback 
+        self.tdeadline = (deadline, next(io_loop._timeout_counter)) 
+ 
+    # Comparison methods to sort by deadline, with object id as a tiebreaker 
+    # to guarantee a consistent ordering.  The heapq module uses __le__ 
+    # in python2.5, and __lt__ in 2.6+ (sort() and most other comparisons 
+    # use __lt__). 
+    def __lt__(self, other): 
+        return self.tdeadline < other.tdeadline 
+ 
+    def __le__(self, other): 
+        return self.tdeadline <= other.tdeadline 
+ 
+ 
+class PeriodicCallback(object): 
+    """Schedules the given callback to be called periodically. 
+ 
+    The callback is called every ``callback_time`` milliseconds. 
+    Note that the timeout is given in milliseconds, while most other 
+    time-related functions in Tornado use seconds. 
+ 
+    If the callback runs for longer than ``callback_time`` milliseconds, 
+    subsequent invocations will be skipped to get back on schedule. 
+ 
+    `start` must be called after the `PeriodicCallback` is created. 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+    """ 
+    def __init__(self, callback, callback_time, io_loop=None): 
+        self.callback = callback 
+        if callback_time <= 0: 
+            raise ValueError("Periodic callback must have a positive callback_time") 
+        self.callback_time = callback_time 
+        self.io_loop = io_loop or IOLoop.current() 
+        self._running = False 
+        self._timeout = None 
+ 
+    def start(self): 
+        """Starts the timer.""" 
+        self._running = True 
+        self._next_timeout = self.io_loop.time() 
+        self._schedule_next() 
+ 
+    def stop(self): 
+        """Stops the timer.""" 
+        self._running = False 
+        if self._timeout is not None: 
+            self.io_loop.remove_timeout(self._timeout) 
+            self._timeout = None 
+ 
+    def is_running(self): 
+        """Return True if this `.PeriodicCallback` has been started. 
+ 
+        .. versionadded:: 4.1 
+        """ 
+        return self._running 
+ 
+    def _run(self): 
+        if not self._running: 
+            return 
+        try: 
+            return self.callback() 
+        except Exception: 
+            self.io_loop.handle_callback_exception(self.callback) 
+        finally: 
+            self._schedule_next() 
+ 
+    def _schedule_next(self): 
+        if self._running: 
+            current_time = self.io_loop.time() 
+ 
+            if self._next_timeout <= current_time: 
+                callback_time_sec = self.callback_time / 1000.0 
+                self._next_timeout += (math.floor((current_time - self._next_timeout) / 
+                                                  callback_time_sec) + 1) * callback_time_sec 
+ 
+            self._timeout = self.io_loop.add_timeout(self._next_timeout, self._run) 
diff --git a/contrib/python/tornado/tornado-4/tornado/iostream.py b/contrib/python/tornado/tornado-4/tornado/iostream.py
index 639ed5082b..359c831234 100644
--- a/contrib/python/tornado/tornado-4/tornado/iostream.py
+++ b/contrib/python/tornado/tornado-4/tornado/iostream.py
@@ -1,1568 +1,1568 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Utility classes to write to and read from non-blocking files and sockets.
-
-Contents:
-
-* `BaseIOStream`: Generic interface for reading and writing.
-* `IOStream`: Implementation of BaseIOStream using non-blocking sockets.
-* `SSLIOStream`: SSL-aware version of IOStream.
-* `PipeIOStream`: Pipe-based IOStream implementation.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import collections
-import errno
-import numbers
-import os
-import socket
-import sys
-import re
-
-from tornado.concurrent import TracebackFuture
-from tornado import ioloop
-from tornado.log import gen_log, app_log
-from tornado.netutil import ssl_wrap_socket, ssl_match_hostname, SSLCertificateError, _client_ssl_defaults, _server_ssl_defaults
-from tornado import stack_context
-from tornado.util import errno_from_exception
-
-try:
-    from tornado.platform.posix import _set_nonblocking
-except ImportError:
-    _set_nonblocking = None
-
-try:
-    import ssl
-except ImportError:
-    # ssl is not available on Google App Engine
-    ssl = None
-
-# These errnos indicate that a non-blocking operation must be retried
-# at a later time.  On most platforms they're the same value, but on
-# some they differ.
-_ERRNO_WOULDBLOCK = (errno.EWOULDBLOCK, errno.EAGAIN)
-
-if hasattr(errno, "WSAEWOULDBLOCK"):
-    _ERRNO_WOULDBLOCK += (errno.WSAEWOULDBLOCK,)  # type: ignore
-
-# These errnos indicate that a connection has been abruptly terminated.
-# They should be caught and handled less noisily than other errors.
-_ERRNO_CONNRESET = (errno.ECONNRESET, errno.ECONNABORTED, errno.EPIPE,
-                    errno.ETIMEDOUT)
-
-if hasattr(errno, "WSAECONNRESET"):
-    _ERRNO_CONNRESET += (errno.WSAECONNRESET, errno.WSAECONNABORTED, errno.WSAETIMEDOUT)  # type: ignore
-
-if sys.platform == 'darwin':
-    # OSX appears to have a race condition that causes send(2) to return
-    # EPROTOTYPE if called while a socket is being torn down:
-    # http://erickt.github.io/blog/2014/11/19/adventures-in-debugging-a-potential-osx-kernel-bug/
-    # Since the socket is being closed anyway, treat this as an ECONNRESET
-    # instead of an unexpected error.
-    _ERRNO_CONNRESET += (errno.EPROTOTYPE,)  # type: ignore
-
-# More non-portable errnos:
-_ERRNO_INPROGRESS = (errno.EINPROGRESS,)
-
-if hasattr(errno, "WSAEINPROGRESS"):
-    _ERRNO_INPROGRESS += (errno.WSAEINPROGRESS,)  # type: ignore
-
-_WINDOWS = sys.platform.startswith('win')
-
-
-class StreamClosedError(IOError):
-    """Exception raised by `IOStream` methods when the stream is closed.
-
-    Note that the close callback is scheduled to run *after* other
-    callbacks on the stream (to allow for buffered data to be processed),
-    so you may see this error before you see the close callback.
-
-    The ``real_error`` attribute contains the underlying error that caused
-    the stream to close (if any).
-
-    .. versionchanged:: 4.3
-       Added the ``real_error`` attribute.
-    """
-    def __init__(self, real_error=None):
-        super(StreamClosedError, self).__init__('Stream is closed')
-        self.real_error = real_error
-
-
-class UnsatisfiableReadError(Exception):
-    """Exception raised when a read cannot be satisfied.
-
-    Raised by ``read_until`` and ``read_until_regex`` with a ``max_bytes``
-    argument.
-    """
-    pass
-
-
-class StreamBufferFullError(Exception):
-    """Exception raised by `IOStream` methods when the buffer is full.
-    """
-
-
-class BaseIOStream(object):
-    """A utility class to write to and read from a non-blocking file or socket.
-
-    We support a non-blocking ``write()`` and a family of ``read_*()`` methods.
-    All of the methods take an optional ``callback`` argument and return a
-    `.Future` only if no callback is given.  When the operation completes,
-    the callback will be run or the `.Future` will resolve with the data
-    read (or ``None`` for ``write()``).  All outstanding ``Futures`` will
-    resolve with a `StreamClosedError` when the stream is closed; users
-    of the callback interface will be notified via
-    `.BaseIOStream.set_close_callback` instead.
-
-    When a stream is closed due to an error, the IOStream's ``error``
-    attribute contains the exception object.
-
-    Subclasses must implement `fileno`, `close_fd`, `write_to_fd`,
-    `read_from_fd`, and optionally `get_fd_error`.
-    """
-    def __init__(self, io_loop=None, max_buffer_size=None,
-                 read_chunk_size=None, max_write_buffer_size=None):
-        """`BaseIOStream` constructor.
-
-        :arg io_loop: The `.IOLoop` to use; defaults to `.IOLoop.current`.
-                      Deprecated since Tornado 4.1.
-        :arg max_buffer_size: Maximum amount of incoming data to buffer;
-            defaults to 100MB.
-        :arg read_chunk_size: Amount of data to read at one time from the
-            underlying transport; defaults to 64KB.
-        :arg max_write_buffer_size: Amount of outgoing data to buffer;
-            defaults to unlimited.
-
-        .. versionchanged:: 4.0
-           Add the ``max_write_buffer_size`` parameter.  Changed default
-           ``read_chunk_size`` to 64KB.
-        """
-        self.io_loop = io_loop or ioloop.IOLoop.current()
-        self.max_buffer_size = max_buffer_size or 104857600
-        # A chunk size that is too close to max_buffer_size can cause
-        # spurious failures.
-        self.read_chunk_size = min(read_chunk_size or 65536,
-                                   self.max_buffer_size // 2)
-        self.max_write_buffer_size = max_write_buffer_size
-        self.error = None
-        self._read_buffer = bytearray()
-        self._read_buffer_pos = 0
-        self._read_buffer_size = 0
-        self._write_buffer = bytearray()
-        self._write_buffer_pos = 0
-        self._write_buffer_size = 0
-        self._write_buffer_frozen = False
-        self._total_write_index = 0
-        self._total_write_done_index = 0
-        self._pending_writes_while_frozen = []
-        self._read_delimiter = None
-        self._read_regex = None
-        self._read_max_bytes = None
-        self._read_bytes = None
-        self._read_partial = False
-        self._read_until_close = False
-        self._read_callback = None
-        self._read_future = None
-        self._streaming_callback = None
-        self._write_callback = None
-        self._write_futures = collections.deque()
-        self._close_callback = None
-        self._connect_callback = None
-        self._connect_future = None
-        # _ssl_connect_future should be defined in SSLIOStream
-        # but it's here so we can clean it up in maybe_run_close_callback.
-        # TODO: refactor that so subclasses can add additional futures
-        # to be cancelled.
-        self._ssl_connect_future = None
-        self._connecting = False
-        self._state = None
-        self._pending_callbacks = 0
-        self._closed = False
-
-    def fileno(self):
-        """Returns the file descriptor for this stream."""
-        raise NotImplementedError()
-
-    def close_fd(self):
-        """Closes the file underlying this stream.
-
-        ``close_fd`` is called by `BaseIOStream` and should not be called
-        elsewhere; other users should call `close` instead.
-        """
-        raise NotImplementedError()
-
-    def write_to_fd(self, data):
-        """Attempts to write ``data`` to the underlying file.
-
-        Returns the number of bytes written.
-        """
-        raise NotImplementedError()
-
-    def read_from_fd(self):
-        """Attempts to read from the underlying file.
-
-        Returns ``None`` if there was nothing to read (the socket
-        returned `~errno.EWOULDBLOCK` or equivalent), otherwise
-        returns the data.  When possible, should return no more than
-        ``self.read_chunk_size`` bytes at a time.
-        """
-        raise NotImplementedError()
-
-    def get_fd_error(self):
-        """Returns information about any error on the underlying file.
-
-        This method is called after the `.IOLoop` has signaled an error on the
-        file descriptor, and should return an Exception (such as `socket.error`
-        with additional information, or None if no such information is
-        available.
-        """
-        return None
-
-    def read_until_regex(self, regex, callback=None, max_bytes=None):
-        """Asynchronously read until we have matched the given regex.
-
-        The result includes the data that matches the regex and anything
-        that came before it.  If a callback is given, it will be run
-        with the data as an argument; if not, this method returns a
-        `.Future`.
-
-        If ``max_bytes`` is not None, the connection will be closed
-        if more than ``max_bytes`` bytes have been read and the regex is
-        not satisfied.
-
-        .. versionchanged:: 4.0
-            Added the ``max_bytes`` argument.  The ``callback`` argument is
-            now optional and a `.Future` will be returned if it is omitted.
-        """
-        future = self._set_read_callback(callback)
-        self._read_regex = re.compile(regex)
-        self._read_max_bytes = max_bytes
-        try:
-            self._try_inline_read()
-        except UnsatisfiableReadError as e:
-            # Handle this the same way as in _handle_events.
-            gen_log.info("Unsatisfiable read, closing connection: %s" % e)
-            self.close(exc_info=True)
-            return future
-        except:
-            if future is not None:
-                # Ensure that the future doesn't log an error because its
-                # failure was never examined.
-                future.add_done_callback(lambda f: f.exception())
-            raise
-        return future
-
-    def read_until(self, delimiter, callback=None, max_bytes=None):
-        """Asynchronously read until we have found the given delimiter.
-
-        The result includes all the data read including the delimiter.
-        If a callback is given, it will be run with the data as an argument;
-        if not, this method returns a `.Future`.
-
-        If ``max_bytes`` is not None, the connection will be closed
-        if more than ``max_bytes`` bytes have been read and the delimiter
-        is not found.
-
-        .. versionchanged:: 4.0
-            Added the ``max_bytes`` argument.  The ``callback`` argument is
-            now optional and a `.Future` will be returned if it is omitted.
-        """
-        future = self._set_read_callback(callback)
-        self._read_delimiter = delimiter
-        self._read_max_bytes = max_bytes
-        try:
-            self._try_inline_read()
-        except UnsatisfiableReadError as e:
-            # Handle this the same way as in _handle_events.
-            gen_log.info("Unsatisfiable read, closing connection: %s" % e)
-            self.close(exc_info=True)
-            return future
-        except:
-            if future is not None:
-                future.add_done_callback(lambda f: f.exception())
-            raise
-        return future
-
-    def read_bytes(self, num_bytes, callback=None, streaming_callback=None,
-                   partial=False):
-        """Asynchronously read a number of bytes.
-
-        If a ``streaming_callback`` is given, it will be called with chunks
-        of data as they become available, and the final result will be empty.
-        Otherwise, the result is all the data that was read.
-        If a callback is given, it will be run with the data as an argument;
-        if not, this method returns a `.Future`.
-
-        If ``partial`` is true, the callback is run as soon as we have
-        any bytes to return (but never more than ``num_bytes``)
-
-        .. versionchanged:: 4.0
-            Added the ``partial`` argument.  The callback argument is now
-            optional and a `.Future` will be returned if it is omitted.
-        """
-        future = self._set_read_callback(callback)
-        assert isinstance(num_bytes, numbers.Integral)
-        self._read_bytes = num_bytes
-        self._read_partial = partial
-        self._streaming_callback = stack_context.wrap(streaming_callback)
-        try:
-            self._try_inline_read()
-        except:
-            if future is not None:
-                future.add_done_callback(lambda f: f.exception())
-            raise
-        return future
-
-    def read_until_close(self, callback=None, streaming_callback=None):
-        """Asynchronously reads all data from the socket until it is closed.
-
-        If a ``streaming_callback`` is given, it will be called with chunks
-        of data as they become available, and the final result will be empty.
-        Otherwise, the result is all the data that was read.
-        If a callback is given, it will be run with the data as an argument;
-        if not, this method returns a `.Future`.
-
-        Note that if a ``streaming_callback`` is used, data will be
-        read from the socket as quickly as it becomes available; there
-        is no way to apply backpressure or cancel the reads. If flow
-        control or cancellation are desired, use a loop with
-        `read_bytes(partial=True) <.read_bytes>` instead.
-
-        .. versionchanged:: 4.0
-            The callback argument is now optional and a `.Future` will
-            be returned if it is omitted.
-
-        """
-        future = self._set_read_callback(callback)
-        self._streaming_callback = stack_context.wrap(streaming_callback)
-        if self.closed():
-            if self._streaming_callback is not None:
-                self._run_read_callback(self._read_buffer_size, True)
-            self._run_read_callback(self._read_buffer_size, False)
-            return future
-        self._read_until_close = True
-        try:
-            self._try_inline_read()
-        except:
-            if future is not None:
-                future.add_done_callback(lambda f: f.exception())
-            raise
-        return future
-
-    def write(self, data, callback=None):
-        """Asynchronously write the given data to this stream.
-
-        If ``callback`` is given, we call it when all of the buffered write
-        data has been successfully written to the stream. If there was
-        previously buffered write data and an old write callback, that
-        callback is simply overwritten with this new callback.
-
-        If no ``callback`` is given, this method returns a `.Future` that
-        resolves (with a result of ``None``) when the write has been
-        completed.
-
-        The ``data`` argument may be of type `bytes` or `memoryview`.
-
-        .. versionchanged:: 4.0
-            Now returns a `.Future` if no callback is given.
-
-        .. versionchanged:: 4.5
-            Added support for `memoryview` arguments.
-        """
-        self._check_closed()
-        if data:
-            if (self.max_write_buffer_size is not None and
-                    self._write_buffer_size + len(data) > self.max_write_buffer_size):
-                raise StreamBufferFullError("Reached maximum write buffer size")
-            if self._write_buffer_frozen:
-                self._pending_writes_while_frozen.append(data)
-            else:
-                self._write_buffer += data
-                self._write_buffer_size += len(data)
-            self._total_write_index += len(data)
-        if callback is not None:
-            self._write_callback = stack_context.wrap(callback)
-            future = None
-        else:
-            future = TracebackFuture()
-            future.add_done_callback(lambda f: f.exception())
-            self._write_futures.append((self._total_write_index, future))
-        if not self._connecting:
-            self._handle_write()
-            if self._write_buffer_size:
-                self._add_io_state(self.io_loop.WRITE)
-            self._maybe_add_error_listener()
-        return future
-
-    def set_close_callback(self, callback):
-        """Call the given callback when the stream is closed.
-
-        This is not necessary for applications that use the `.Future`
-        interface; all outstanding ``Futures`` will resolve with a
-        `StreamClosedError` when the stream is closed.
-        """
-        self._close_callback = stack_context.wrap(callback)
-        self._maybe_add_error_listener()
-
-    def close(self, exc_info=False):
-        """Close this stream.
-
-        If ``exc_info`` is true, set the ``error`` attribute to the current
-        exception from `sys.exc_info` (or if ``exc_info`` is a tuple,
-        use that instead of `sys.exc_info`).
-        """
-        if not self.closed():
-            if exc_info:
-                if not isinstance(exc_info, tuple):
-                    exc_info = sys.exc_info()
-                if any(exc_info):
-                    self.error = exc_info[1]
-            if self._read_until_close:
-                if (self._streaming_callback is not None and
-                        self._read_buffer_size):
-                    self._run_read_callback(self._read_buffer_size, True)
-                self._read_until_close = False
-                self._run_read_callback(self._read_buffer_size, False)
-            if self._state is not None:
-                self.io_loop.remove_handler(self.fileno())
-                self._state = None
-            self.close_fd()
-            self._closed = True
-        self._maybe_run_close_callback()
-
-    def _maybe_run_close_callback(self):
-        # If there are pending callbacks, don't run the close callback
-        # until they're done (see _maybe_add_error_handler)
-        if self.closed() and self._pending_callbacks == 0:
-            futures = []
-            if self._read_future is not None:
-                futures.append(self._read_future)
-                self._read_future = None
-            futures += [future for _, future in self._write_futures]
-            self._write_futures.clear()
-            if self._connect_future is not None:
-                futures.append(self._connect_future)
-                self._connect_future = None
-            if self._ssl_connect_future is not None:
-                futures.append(self._ssl_connect_future)
-                self._ssl_connect_future = None
-            for future in futures:
-                future.set_exception(StreamClosedError(real_error=self.error))
-            if self._close_callback is not None:
-                cb = self._close_callback
-                self._close_callback = None
-                self._run_callback(cb)
-            # Delete any unfinished callbacks to break up reference cycles.
-            self._read_callback = self._write_callback = None
-            # Clear the buffers so they can be cleared immediately even
-            # if the IOStream object is kept alive by a reference cycle.
-            # TODO: Clear the read buffer too; it currently breaks some tests.
-            self._write_buffer = None
-            self._write_buffer_size = 0
-
-    def reading(self):
-        """Returns true if we are currently reading from the stream."""
-        return self._read_callback is not None or self._read_future is not None
-
-    def writing(self):
-        """Returns true if we are currently writing to the stream."""
-        return self._write_buffer_size > 0
-
-    def closed(self):
-        """Returns true if the stream has been closed."""
-        return self._closed
-
-    def set_nodelay(self, value):
-        """Sets the no-delay flag for this stream.
-
-        By default, data written to TCP streams may be held for a time
-        to make the most efficient use of bandwidth (according to
-        Nagle's algorithm).  The no-delay flag requests that data be
-        written as soon as possible, even if doing so would consume
-        additional bandwidth.
-
-        This flag is currently defined only for TCP-based ``IOStreams``.
-
-        .. versionadded:: 3.1
-        """
-        pass
-
-    def _handle_events(self, fd, events):
-        if self.closed():
-            gen_log.warning("Got events for closed stream %s", fd)
-            return
-        try:
-            if self._connecting:
-                # Most IOLoops will report a write failed connect
-                # with the WRITE event, but SelectIOLoop reports a
-                # READ as well so we must check for connecting before
-                # either.
-                self._handle_connect()
-            if self.closed():
-                return
-            if events & self.io_loop.READ:
-                self._handle_read()
-            if self.closed():
-                return
-            if events & self.io_loop.WRITE:
-                self._handle_write()
-            if self.closed():
-                return
-            if events & self.io_loop.ERROR:
-                self.error = self.get_fd_error()
-                # We may have queued up a user callback in _handle_read or
-                # _handle_write, so don't close the IOStream until those
-                # callbacks have had a chance to run.
-                self.io_loop.add_callback(self.close)
-                return
-            state = self.io_loop.ERROR
-            if self.reading():
-                state |= self.io_loop.READ
-            if self.writing():
-                state |= self.io_loop.WRITE
-            if state == self.io_loop.ERROR and self._read_buffer_size == 0:
-                # If the connection is idle, listen for reads too so
-                # we can tell if the connection is closed.  If there is
-                # data in the read buffer we won't run the close callback
-                # yet anyway, so we don't need to listen in this case.
-                state |= self.io_loop.READ
-            if state != self._state:
-                assert self._state is not None, \
-                    "shouldn't happen: _handle_events without self._state"
-                self._state = state
-                self.io_loop.update_handler(self.fileno(), self._state)
-        except UnsatisfiableReadError as e:
-            gen_log.info("Unsatisfiable read, closing connection: %s" % e)
-            self.close(exc_info=True)
-        except Exception:
-            gen_log.error("Uncaught exception, closing connection.",
-                          exc_info=True)
-            self.close(exc_info=True)
-            raise
-
-    def _run_callback(self, callback, *args):
-        def wrapper():
-            self._pending_callbacks -= 1
-            try:
-                return callback(*args)
-            except Exception:
-                app_log.error("Uncaught exception, closing connection.",
-                              exc_info=True)
-                # Close the socket on an uncaught exception from a user callback
-                # (It would eventually get closed when the socket object is
-                # gc'd, but we don't want to rely on gc happening before we
-                # run out of file descriptors)
-                self.close(exc_info=True)
-                # Re-raise the exception so that IOLoop.handle_callback_exception
-                # can see it and log the error
-                raise
-            finally:
-                self._maybe_add_error_listener()
-        # We schedule callbacks to be run on the next IOLoop iteration
-        # rather than running them directly for several reasons:
-        # * Prevents unbounded stack growth when a callback calls an
-        #   IOLoop operation that immediately runs another callback
-        # * Provides a predictable execution context for e.g.
-        #   non-reentrant mutexes
-        # * Ensures that the try/except in wrapper() is run outside
-        #   of the application's StackContexts
-        with stack_context.NullContext():
-            # stack_context was already captured in callback, we don't need to
-            # capture it again for IOStream's wrapper.  This is especially
-            # important if the callback was pre-wrapped before entry to
-            # IOStream (as in HTTPConnection._header_callback), as we could
-            # capture and leak the wrong context here.
-            self._pending_callbacks += 1
-            self.io_loop.add_callback(wrapper)
-
-    def _read_to_buffer_loop(self):
-        # This method is called from _handle_read and _try_inline_read.
-        try:
-            if self._read_bytes is not None:
-                target_bytes = self._read_bytes
-            elif self._read_max_bytes is not None:
-                target_bytes = self._read_max_bytes
-            elif self.reading():
-                # For read_until without max_bytes, or
-                # read_until_close, read as much as we can before
-                # scanning for the delimiter.
-                target_bytes = None
-            else:
-                target_bytes = 0
-            next_find_pos = 0
-            # Pretend to have a pending callback so that an EOF in
-            # _read_to_buffer doesn't trigger an immediate close
-            # callback.  At the end of this method we'll either
-            # establish a real pending callback via
-            # _read_from_buffer or run the close callback.
-            #
-            # We need two try statements here so that
-            # pending_callbacks is decremented before the `except`
-            # clause below (which calls `close` and does need to
-            # trigger the callback)
-            self._pending_callbacks += 1
-            while not self.closed():
-                # Read from the socket until we get EWOULDBLOCK or equivalent.
-                # SSL sockets do some internal buffering, and if the data is
-                # sitting in the SSL object's buffer select() and friends
-                # can't see it; the only way to find out if it's there is to
-                # try to read it.
-                if self._read_to_buffer() == 0:
-                    break
-
-                self._run_streaming_callback()
-
-                # If we've read all the bytes we can use, break out of
-                # this loop.  We can't just call read_from_buffer here
-                # because of subtle interactions with the
-                # pending_callback and error_listener mechanisms.
-                #
-                # If we've reached target_bytes, we know we're done.
-                if (target_bytes is not None and
-                        self._read_buffer_size >= target_bytes):
-                    break
-
-                # Otherwise, we need to call the more expensive find_read_pos.
-                # It's inefficient to do this on every read, so instead
-                # do it on the first read and whenever the read buffer
-                # size has doubled.
-                if self._read_buffer_size >= next_find_pos:
-                    pos = self._find_read_pos()
-                    if pos is not None:
-                        return pos
-                    next_find_pos = self._read_buffer_size * 2
-            return self._find_read_pos()
-        finally:
-            self._pending_callbacks -= 1
-
-    def _handle_read(self):
-        try:
-            pos = self._read_to_buffer_loop()
-        except UnsatisfiableReadError:
-            raise
-        except Exception as e:
-            gen_log.warning("error on read: %s" % e)
-            self.close(exc_info=True)
-            return
-        if pos is not None:
-            self._read_from_buffer(pos)
-            return
-        else:
-            self._maybe_run_close_callback()
-
-    def _set_read_callback(self, callback):
-        assert self._read_callback is None, "Already reading"
-        assert self._read_future is None, "Already reading"
-        if callback is not None:
-            self._read_callback = stack_context.wrap(callback)
-        else:
-            self._read_future = TracebackFuture()
-        return self._read_future
-
-    def _run_read_callback(self, size, streaming):
-        if streaming:
-            callback = self._streaming_callback
-        else:
-            callback = self._read_callback
-            self._read_callback = self._streaming_callback = None
-            if self._read_future is not None:
-                assert callback is None
-                future = self._read_future
-                self._read_future = None
-                future.set_result(self._consume(size))
-        if callback is not None:
-            assert (self._read_future is None) or streaming
-            self._run_callback(callback, self._consume(size))
-        else:
-            # If we scheduled a callback, we will add the error listener
-            # afterwards.  If we didn't, we have to do it now.
-            self._maybe_add_error_listener()
-
-    def _try_inline_read(self):
-        """Attempt to complete the current read operation from buffered data.
-
-        If the read can be completed without blocking, schedules the
-        read callback on the next IOLoop iteration; otherwise starts
-        listening for reads on the socket.
-        """
-        # See if we've already got the data from a previous read
-        self._run_streaming_callback()
-        pos = self._find_read_pos()
-        if pos is not None:
-            self._read_from_buffer(pos)
-            return
-        self._check_closed()
-        try:
-            pos = self._read_to_buffer_loop()
-        except Exception:
-            # If there was an in _read_to_buffer, we called close() already,
-            # but couldn't run the close callback because of _pending_callbacks.
-            # Before we escape from this function, run the close callback if
-            # applicable.
-            self._maybe_run_close_callback()
-            raise
-        if pos is not None:
-            self._read_from_buffer(pos)
-            return
-        # We couldn't satisfy the read inline, so either close the stream
-        # or listen for new data.
-        if self.closed():
-            self._maybe_run_close_callback()
-        else:
-            self._add_io_state(ioloop.IOLoop.READ)
-
-    def _read_to_buffer(self):
-        """Reads from the socket and appends the result to the read buffer.
-
-        Returns the number of bytes read.  Returns 0 if there is nothing
-        to read (i.e. the read returns EWOULDBLOCK or equivalent).  On
-        error closes the socket and raises an exception.
-        """
-        while True:
-            try:
-                chunk = self.read_from_fd()
-            except (socket.error, IOError, OSError) as e:
-                if errno_from_exception(e) == errno.EINTR:
-                    continue
-                # ssl.SSLError is a subclass of socket.error
-                if self._is_connreset(e):
-                    # Treat ECONNRESET as a connection close rather than
-                    # an error to minimize log spam  (the exception will
-                    # be available on self.error for apps that care).
-                    self.close(exc_info=True)
-                    return
-                self.close(exc_info=True)
-                raise
-            break
-        if chunk is None:
-            return 0
-        self._read_buffer += chunk
-        self._read_buffer_size += len(chunk)
-        if self._read_buffer_size > self.max_buffer_size:
-            gen_log.error("Reached maximum read buffer size")
-            self.close()
-            raise StreamBufferFullError("Reached maximum read buffer size")
-        return len(chunk)
-
-    def _run_streaming_callback(self):
-        if self._streaming_callback is not None and self._read_buffer_size:
-            bytes_to_consume = self._read_buffer_size
-            if self._read_bytes is not None:
-                bytes_to_consume = min(self._read_bytes, bytes_to_consume)
-                self._read_bytes -= bytes_to_consume
-            self._run_read_callback(bytes_to_consume, True)
-
-    def _read_from_buffer(self, pos):
-        """Attempts to complete the currently-pending read from the buffer.
-
-        The argument is either a position in the read buffer or None,
-        as returned by _find_read_pos.
-        """
-        self._read_bytes = self._read_delimiter = self._read_regex = None
-        self._read_partial = False
-        self._run_read_callback(pos, False)
-
-    def _find_read_pos(self):
-        """Attempts to find a position in the read buffer that satisfies
-        the currently-pending read.
-
-        Returns a position in the buffer if the current read can be satisfied,
-        or None if it cannot.
-        """
-        if (self._read_bytes is not None and
-            (self._read_buffer_size >= self._read_bytes or
-             (self._read_partial and self._read_buffer_size > 0))):
-            num_bytes = min(self._read_bytes, self._read_buffer_size)
-            return num_bytes
-        elif self._read_delimiter is not None:
-            # Multi-byte delimiters (e.g. '\r\n') may straddle two
-            # chunks in the read buffer, so we can't easily find them
-            # without collapsing the buffer.  However, since protocols
-            # using delimited reads (as opposed to reads of a known
-            # length) tend to be "line" oriented, the delimiter is likely
-            # to be in the first few chunks.  Merge the buffer gradually
-            # since large merges are relatively expensive and get undone in
-            # _consume().
-            if self._read_buffer:
-                loc = self._read_buffer.find(self._read_delimiter,
-                                             self._read_buffer_pos)
-                if loc != -1:
-                    loc -= self._read_buffer_pos
-                    delimiter_len = len(self._read_delimiter)
-                    self._check_max_bytes(self._read_delimiter,
-                                          loc + delimiter_len)
-                    return loc + delimiter_len
-                self._check_max_bytes(self._read_delimiter,
-                                      self._read_buffer_size)
-        elif self._read_regex is not None:
-            if self._read_buffer:
-                m = self._read_regex.search(self._read_buffer,
-                                            self._read_buffer_pos)
-                if m is not None:
-                    loc = m.end() - self._read_buffer_pos
-                    self._check_max_bytes(self._read_regex, loc)
-                    return loc
-                self._check_max_bytes(self._read_regex, self._read_buffer_size)
-        return None
-
-    def _check_max_bytes(self, delimiter, size):
-        if (self._read_max_bytes is not None and
-                size > self._read_max_bytes):
-            raise UnsatisfiableReadError(
-                "delimiter %r not found within %d bytes" % (
-                    delimiter, self._read_max_bytes))
-
-    def _freeze_write_buffer(self, size):
-        self._write_buffer_frozen = size
-
-    def _unfreeze_write_buffer(self):
-        self._write_buffer_frozen = False
-        self._write_buffer += b''.join(self._pending_writes_while_frozen)
-        self._write_buffer_size += sum(map(len, self._pending_writes_while_frozen))
-        self._pending_writes_while_frozen[:] = []
-
-    def _got_empty_write(self, size):
-        """
-        Called when a non-blocking write() failed writing anything.
-        Can be overridden in subclasses.
-        """
-
-    def _handle_write(self):
-        while self._write_buffer_size:
-            assert self._write_buffer_size >= 0
-            try:
-                start = self._write_buffer_pos
-                if self._write_buffer_frozen:
-                    size = self._write_buffer_frozen
-                elif _WINDOWS:
-                    # On windows, socket.send blows up if given a
-                    # write buffer that's too large, instead of just
-                    # returning the number of bytes it was able to
-                    # process.  Therefore we must not call socket.send
-                    # with more than 128KB at a time.
-                    size = 128 * 1024
-                else:
-                    size = self._write_buffer_size
-                num_bytes = self.write_to_fd(
-                    memoryview(self._write_buffer)[start:start + size])
-                if num_bytes == 0:
-                    self._got_empty_write(size)
-                    break
-                self._write_buffer_pos += num_bytes
-                self._write_buffer_size -= num_bytes
-                # Amortized O(1) shrink
-                # (this heuristic is implemented natively in Python 3.4+
-                #  but is replicated here for Python 2)
-                if self._write_buffer_pos > self._write_buffer_size:
-                    del self._write_buffer[:self._write_buffer_pos]
-                    self._write_buffer_pos = 0
-                if self._write_buffer_frozen:
-                    self._unfreeze_write_buffer()
-                self._total_write_done_index += num_bytes
-            except (socket.error, IOError, OSError) as e:
-                if e.args[0] in _ERRNO_WOULDBLOCK:
-                    self._got_empty_write(size)
-                    break
-                else:
-                    if not self._is_connreset(e):
-                        # Broken pipe errors are usually caused by connection
-                        # reset, and its better to not log EPIPE errors to
-                        # minimize log spam
-                        gen_log.warning("Write error on %s: %s",
-                                        self.fileno(), e)
-                    self.close(exc_info=True)
-                    return
-
-        while self._write_futures:
-            index, future = self._write_futures[0]
-            if index > self._total_write_done_index:
-                break
-            self._write_futures.popleft()
-            future.set_result(None)
-
-        if not self._write_buffer_size:
-            if self._write_callback:
-                callback = self._write_callback
-                self._write_callback = None
-                self._run_callback(callback)
-
-    def _consume(self, loc):
-        # Consume loc bytes from the read buffer and return them
-        if loc == 0:
-            return b""
-        assert loc <= self._read_buffer_size
-        # Slice the bytearray buffer into bytes, without intermediate copying
-        b = (memoryview(self._read_buffer)
-             [self._read_buffer_pos:self._read_buffer_pos + loc]
-             ).tobytes()
-        self._read_buffer_pos += loc
-        self._read_buffer_size -= loc
-        # Amortized O(1) shrink
-        # (this heuristic is implemented natively in Python 3.4+
-        #  but is replicated here for Python 2)
-        if self._read_buffer_pos > self._read_buffer_size:
-            del self._read_buffer[:self._read_buffer_pos]
-            self._read_buffer_pos = 0
-        return b
-
-    def _check_closed(self):
-        if self.closed():
-            raise StreamClosedError(real_error=self.error)
-
-    def _maybe_add_error_listener(self):
-        # This method is part of an optimization: to detect a connection that
-        # is closed when we're not actively reading or writing, we must listen
-        # for read events.  However, it is inefficient to do this when the
-        # connection is first established because we are going to read or write
-        # immediately anyway.  Instead, we insert checks at various times to
-        # see if the connection is idle and add the read listener then.
-        if self._pending_callbacks != 0:
-            return
-        if self._state is None or self._state == ioloop.IOLoop.ERROR:
-            if self.closed():
-                self._maybe_run_close_callback()
-            elif (self._read_buffer_size == 0 and
-                  self._close_callback is not None):
-                self._add_io_state(ioloop.IOLoop.READ)
-
-    def _add_io_state(self, state):
-        """Adds `state` (IOLoop.{READ,WRITE} flags) to our event handler.
-
-        Implementation notes: Reads and writes have a fast path and a
-        slow path.  The fast path reads synchronously from socket
-        buffers, while the slow path uses `_add_io_state` to schedule
-        an IOLoop callback.  Note that in both cases, the callback is
-        run asynchronously with `_run_callback`.
-
-        To detect closed connections, we must have called
-        `_add_io_state` at some point, but we want to delay this as
-        much as possible so we don't have to set an `IOLoop.ERROR`
-        listener that will be overwritten by the next slow-path
-        operation.  As long as there are callbacks scheduled for
-        fast-path ops, those callbacks may do more reads.
-        If a sequence of fast-path ops do not end in a slow-path op,
-        (e.g. for an @asynchronous long-poll request), we must add
-        the error handler.  This is done in `_run_callback` and `write`
-        (since the write callback is optional so we can have a
-        fast-path write with no `_run_callback`)
-        """
-        if self.closed():
-            # connection has been closed, so there can be no future events
-            return
-        if self._state is None:
-            self._state = ioloop.IOLoop.ERROR | state
-            with stack_context.NullContext():
-                self.io_loop.add_handler(
-                    self.fileno(), self._handle_events, self._state)
-        elif not self._state & state:
-            self._state = self._state | state
-            self.io_loop.update_handler(self.fileno(), self._state)
-
-    def _is_connreset(self, exc):
-        """Return true if exc is ECONNRESET or equivalent.
-
-        May be overridden in subclasses.
-        """
-        return (isinstance(exc, (socket.error, IOError)) and
-                errno_from_exception(exc) in _ERRNO_CONNRESET)
-
-
-class IOStream(BaseIOStream):
-    r"""Socket-based `IOStream` implementation.
-
-    This class supports the read and write methods from `BaseIOStream`
-    plus a `connect` method.
-
-    The ``socket`` parameter may either be connected or unconnected.
-    For server operations the socket is the result of calling
-    `socket.accept <socket.socket.accept>`.  For client operations the
-    socket is created with `socket.socket`, and may either be
-    connected before passing it to the `IOStream` or connected with
-    `IOStream.connect`.
-
-    A very simple (and broken) HTTP client using this class:
-
-    .. testcode::
-
-        import tornado.ioloop
-        import tornado.iostream
-        import socket
-
-        def send_request():
-            stream.write(b"GET / HTTP/1.0\r\nHost: friendfeed.com\r\n\r\n")
-            stream.read_until(b"\r\n\r\n", on_headers)
-
-        def on_headers(data):
-            headers = {}
-            for line in data.split(b"\r\n"):
-               parts = line.split(b":")
-               if len(parts) == 2:
-                   headers[parts[0].strip()] = parts[1].strip()
-            stream.read_bytes(int(headers[b"Content-Length"]), on_body)
-
-        def on_body(data):
-            print(data)
-            stream.close()
-            tornado.ioloop.IOLoop.current().stop()
-
-        if __name__ == '__main__':
-            s = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
-            stream = tornado.iostream.IOStream(s)
-            stream.connect(("friendfeed.com", 80), send_request)
-            tornado.ioloop.IOLoop.current().start()
-
-    .. testoutput::
-       :hide:
-
-    """
-    def __init__(self, socket, *args, **kwargs):
-        self.socket = socket
-        self.socket.setblocking(False)
-        super(IOStream, self).__init__(*args, **kwargs)
-
-    def fileno(self):
-        return self.socket
-
-    def close_fd(self):
-        self.socket.close()
-        self.socket = None
-
-    def get_fd_error(self):
-        errno = self.socket.getsockopt(socket.SOL_SOCKET,
-                                       socket.SO_ERROR)
-        return socket.error(errno, os.strerror(errno))
-
-    def read_from_fd(self):
-        try:
-            chunk = self.socket.recv(self.read_chunk_size)
-        except socket.error as e:
-            if e.args[0] in _ERRNO_WOULDBLOCK:
-                return None
-            else:
-                raise
-        if not chunk:
-            self.close()
-            return None
-        return chunk
-
-    def write_to_fd(self, data):
-        try:
-            return self.socket.send(data)
-        finally:
-            # Avoid keeping to data, which can be a memoryview.
-            # See https://github.com/tornadoweb/tornado/pull/2008
-            del data
-
-    def connect(self, address, callback=None, server_hostname=None):
-        """Connects the socket to a remote address without blocking.
-
-        May only be called if the socket passed to the constructor was
-        not previously connected.  The address parameter is in the
-        same format as for `socket.connect <socket.socket.connect>` for
-        the type of socket passed to the IOStream constructor,
-        e.g. an ``(ip, port)`` tuple.  Hostnames are accepted here,
-        but will be resolved synchronously and block the IOLoop.
-        If you have a hostname instead of an IP address, the `.TCPClient`
-        class is recommended instead of calling this method directly.
-        `.TCPClient` will do asynchronous DNS resolution and handle
-        both IPv4 and IPv6.
-
-        If ``callback`` is specified, it will be called with no
-        arguments when the connection is completed; if not this method
-        returns a `.Future` (whose result after a successful
-        connection will be the stream itself).
-
-        In SSL mode, the ``server_hostname`` parameter will be used
-        for certificate validation (unless disabled in the
-        ``ssl_options``) and SNI (if supported; requires Python
-        2.7.9+).
-
-        Note that it is safe to call `IOStream.write
-        <BaseIOStream.write>` while the connection is pending, in
-        which case the data will be written as soon as the connection
-        is ready.  Calling `IOStream` read methods before the socket is
-        connected works on some platforms but is non-portable.
-
-        .. versionchanged:: 4.0
-            If no callback is given, returns a `.Future`.
-
-        .. versionchanged:: 4.2
-           SSL certificates are validated by default; pass
-           ``ssl_options=dict(cert_reqs=ssl.CERT_NONE)`` or a
-           suitably-configured `ssl.SSLContext` to the
-           `SSLIOStream` constructor to disable.
-        """
-        self._connecting = True
-        if callback is not None:
-            self._connect_callback = stack_context.wrap(callback)
-            future = None
-        else:
-            future = self._connect_future = TracebackFuture()
-        try:
-            self.socket.connect(address)
-        except socket.error as e:
-            # In non-blocking mode we expect connect() to raise an
-            # exception with EINPROGRESS or EWOULDBLOCK.
-            #
-            # On freebsd, other errors such as ECONNREFUSED may be
-            # returned immediately when attempting to connect to
-            # localhost, so handle them the same way as an error
-            # reported later in _handle_connect.
-            if (errno_from_exception(e) not in _ERRNO_INPROGRESS and
-                    errno_from_exception(e) not in _ERRNO_WOULDBLOCK):
-                if future is None:
-                    gen_log.warning("Connect error on fd %s: %s",
-                                    self.socket.fileno(), e)
-                self.close(exc_info=True)
-                return future
-        self._add_io_state(self.io_loop.WRITE)
-        return future
-
-    def start_tls(self, server_side, ssl_options=None, server_hostname=None):
-        """Convert this `IOStream` to an `SSLIOStream`.
-
-        This enables protocols that begin in clear-text mode and
-        switch to SSL after some initial negotiation (such as the
-        ``STARTTLS`` extension to SMTP and IMAP).
-
-        This method cannot be used if there are outstanding reads
-        or writes on the stream, or if there is any data in the
-        IOStream's buffer (data in the operating system's socket
-        buffer is allowed).  This means it must generally be used
-        immediately after reading or writing the last clear-text
-        data.  It can also be used immediately after connecting,
-        before any reads or writes.
-
-        The ``ssl_options`` argument may be either an `ssl.SSLContext`
-        object or a dictionary of keyword arguments for the
-        `ssl.wrap_socket` function.  The ``server_hostname`` argument
-        will be used for certificate validation unless disabled
-        in the ``ssl_options``.
-
-        This method returns a `.Future` whose result is the new
-        `SSLIOStream`.  After this method has been called,
-        any other operation on the original stream is undefined.
-
-        If a close callback is defined on this stream, it will be
-        transferred to the new stream.
-
-        .. versionadded:: 4.0
-
-        .. versionchanged:: 4.2
-           SSL certificates are validated by default; pass
-           ``ssl_options=dict(cert_reqs=ssl.CERT_NONE)`` or a
-           suitably-configured `ssl.SSLContext` to disable.
-        """
-        if (self._read_callback or self._read_future or
-                self._write_callback or self._write_futures or
-                self._connect_callback or self._connect_future or
-                self._pending_callbacks or self._closed or
-                self._read_buffer or self._write_buffer):
-            raise ValueError("IOStream is not idle; cannot convert to SSL")
-        if ssl_options is None:
-            if server_side:
-                ssl_options = _server_ssl_defaults
-            else:
-                ssl_options = _client_ssl_defaults
-
-        socket = self.socket
-        self.io_loop.remove_handler(socket)
-        self.socket = None
-        socket = ssl_wrap_socket(socket, ssl_options,
-                                 server_hostname=server_hostname,
-                                 server_side=server_side,
-                                 do_handshake_on_connect=False)
-        orig_close_callback = self._close_callback
-        self._close_callback = None
-
-        future = TracebackFuture()
-        ssl_stream = SSLIOStream(socket, ssl_options=ssl_options,
-                                 io_loop=self.io_loop)
-        # Wrap the original close callback so we can fail our Future as well.
-        # If we had an "unwrap" counterpart to this method we would need
-        # to restore the original callback after our Future resolves
-        # so that repeated wrap/unwrap calls don't build up layers.
-
-        def close_callback():
-            if not future.done():
-                # Note that unlike most Futures returned by IOStream,
-                # this one passes the underlying error through directly
-                # instead of wrapping everything in a StreamClosedError
-                # with a real_error attribute. This is because once the
-                # connection is established it's more helpful to raise
-                # the SSLError directly than to hide it behind a
-                # StreamClosedError (and the client is expecting SSL
-                # issues rather than network issues since this method is
-                # named start_tls).
-                future.set_exception(ssl_stream.error or StreamClosedError())
-            if orig_close_callback is not None:
-                orig_close_callback()
-        ssl_stream.set_close_callback(close_callback)
-        ssl_stream._ssl_connect_callback = lambda: future.set_result(ssl_stream)
-        ssl_stream.max_buffer_size = self.max_buffer_size
-        ssl_stream.read_chunk_size = self.read_chunk_size
-        return future
-
-    def _handle_connect(self):
-        err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
-        if err != 0:
-            self.error = socket.error(err, os.strerror(err))
-            # IOLoop implementations may vary: some of them return
-            # an error state before the socket becomes writable, so
-            # in that case a connection failure would be handled by the
-            # error path in _handle_events instead of here.
-            if self._connect_future is None:
-                gen_log.warning("Connect error on fd %s: %s",
-                                self.socket.fileno(), errno.errorcode[err])
-            self.close()
-            return
-        if self._connect_callback is not None:
-            callback = self._connect_callback
-            self._connect_callback = None
-            self._run_callback(callback)
-        if self._connect_future is not None:
-            future = self._connect_future
-            self._connect_future = None
-            future.set_result(self)
-        self._connecting = False
-
-    def set_nodelay(self, value):
-        if (self.socket is not None and
-                self.socket.family in (socket.AF_INET, socket.AF_INET6)):
-            try:
-                self.socket.setsockopt(socket.IPPROTO_TCP,
-                                       socket.TCP_NODELAY, 1 if value else 0)
-            except socket.error as e:
-                # Sometimes setsockopt will fail if the socket is closed
-                # at the wrong time.  This can happen with HTTPServer
-                # resetting the value to false between requests.
-                if e.errno != errno.EINVAL and not self._is_connreset(e):
-                    raise
-
-
-class SSLIOStream(IOStream):
-    """A utility class to write to and read from a non-blocking SSL socket.
-
-    If the socket passed to the constructor is already connected,
-    it should be wrapped with::
-
-        ssl.wrap_socket(sock, do_handshake_on_connect=False, **kwargs)
-
-    before constructing the `SSLIOStream`.  Unconnected sockets will be
-    wrapped when `IOStream.connect` is finished.
-    """
-    def __init__(self, *args, **kwargs):
-        """The ``ssl_options`` keyword argument may either be an
-        `ssl.SSLContext` object or a dictionary of keywords arguments
-        for `ssl.wrap_socket`
-        """
-        self._ssl_options = kwargs.pop('ssl_options', _client_ssl_defaults)
-        super(SSLIOStream, self).__init__(*args, **kwargs)
-        self._ssl_accepting = True
-        self._handshake_reading = False
-        self._handshake_writing = False
-        self._ssl_connect_callback = None
-        self._server_hostname = None
-
-        # If the socket is already connected, attempt to start the handshake.
-        try:
-            self.socket.getpeername()
-        except socket.error:
-            pass
-        else:
-            # Indirectly start the handshake, which will run on the next
-            # IOLoop iteration and then the real IO state will be set in
-            # _handle_events.
-            self._add_io_state(self.io_loop.WRITE)
-
-    def reading(self):
-        return self._handshake_reading or super(SSLIOStream, self).reading()
-
-    def writing(self):
-        return self._handshake_writing or super(SSLIOStream, self).writing()
-
-    def _got_empty_write(self, size):
-        # With OpenSSL, if we couldn't write the entire buffer,
-        # the very same string object must be used on the
-        # next call to send.  Therefore we suppress
-        # merging the write buffer after an incomplete send.
-        # A cleaner solution would be to set
-        # SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER, but this is
-        # not yet accessible from python
-        # (http://bugs.python.org/issue8240)
-        self._freeze_write_buffer(size)
-
-    def _do_ssl_handshake(self):
-        # Based on code from test_ssl.py in the python stdlib
-        try:
-            self._handshake_reading = False
-            self._handshake_writing = False
-            self.socket.do_handshake()
-        except ssl.SSLError as err:
-            if err.args[0] == ssl.SSL_ERROR_WANT_READ:
-                self._handshake_reading = True
-                return
-            elif err.args[0] == ssl.SSL_ERROR_WANT_WRITE:
-                self._handshake_writing = True
-                return
-            elif err.args[0] in (ssl.SSL_ERROR_EOF,
-                                 ssl.SSL_ERROR_ZERO_RETURN):
-                return self.close(exc_info=True)
-            elif err.args[0] == ssl.SSL_ERROR_SSL:
-                try:
-                    peer = self.socket.getpeername()
-                except Exception:
-                    peer = '(not connected)'
-                gen_log.warning("SSL Error on %s %s: %s",
-                                self.socket.fileno(), peer, err)
-                return self.close(exc_info=True)
-            raise
-        except socket.error as err:
-            # Some port scans (e.g. nmap in -sT mode) have been known
-            # to cause do_handshake to raise EBADF and ENOTCONN, so make
-            # those errors quiet as well.
-            # https://groups.google.com/forum/?fromgroups#!topic/python-tornado/ApucKJat1_0
-            if (self._is_connreset(err) or
-                    err.args[0] in (errno.EBADF, errno.ENOTCONN)):
-                return self.close(exc_info=True)
-            raise
-        except AttributeError:
-            # On Linux, if the connection was reset before the call to
-            # wrap_socket, do_handshake will fail with an
-            # AttributeError.
-            return self.close(exc_info=True)
-        else:
-            self._ssl_accepting = False
-            if not self._verify_cert(self.socket.getpeercert()):
-                self.close()
-                return
-            self._run_ssl_connect_callback()
-
-    def _run_ssl_connect_callback(self):
-        if self._ssl_connect_callback is not None:
-            callback = self._ssl_connect_callback
-            self._ssl_connect_callback = None
-            self._run_callback(callback)
-        if self._ssl_connect_future is not None:
-            future = self._ssl_connect_future
-            self._ssl_connect_future = None
-            future.set_result(self)
-
-    def _verify_cert(self, peercert):
-        """Returns True if peercert is valid according to the configured
-        validation mode and hostname.
-
-        The ssl handshake already tested the certificate for a valid
-        CA signature; the only thing that remains is to check
-        the hostname.
-        """
-        if isinstance(self._ssl_options, dict):
-            verify_mode = self._ssl_options.get('cert_reqs', ssl.CERT_NONE)
-        elif isinstance(self._ssl_options, ssl.SSLContext):
-            verify_mode = self._ssl_options.verify_mode
-        assert verify_mode in (ssl.CERT_NONE, ssl.CERT_REQUIRED, ssl.CERT_OPTIONAL)
-        if verify_mode == ssl.CERT_NONE or self._server_hostname is None:
-            return True
-        cert = self.socket.getpeercert()
-        if cert is None and verify_mode == ssl.CERT_REQUIRED:
-            gen_log.warning("No SSL certificate given")
-            return False
-        try:
-            ssl_match_hostname(peercert, self._server_hostname)
-        except SSLCertificateError as e:
-            gen_log.warning("Invalid SSL certificate: %s" % e)
-            return False
-        else:
-            return True
-
-    def _handle_read(self):
-        if self._ssl_accepting:
-            self._do_ssl_handshake()
-            return
-        super(SSLIOStream, self)._handle_read()
-
-    def _handle_write(self):
-        if self._ssl_accepting:
-            self._do_ssl_handshake()
-            return
-        super(SSLIOStream, self)._handle_write()
-
-    def connect(self, address, callback=None, server_hostname=None):
-        self._server_hostname = server_hostname
-        # Pass a dummy callback to super.connect(), which is slightly
-        # more efficient than letting it return a Future we ignore.
-        super(SSLIOStream, self).connect(address, callback=lambda: None)
-        return self.wait_for_handshake(callback)
-
-    def _handle_connect(self):
-        # Call the superclass method to check for errors.
-        super(SSLIOStream, self)._handle_connect()
-        if self.closed():
-            return
-        # When the connection is complete, wrap the socket for SSL
-        # traffic.  Note that we do this by overriding _handle_connect
-        # instead of by passing a callback to super().connect because
-        # user callbacks are enqueued asynchronously on the IOLoop,
-        # but since _handle_events calls _handle_connect immediately
-        # followed by _handle_write we need this to be synchronous.
-        #
-        # The IOLoop will get confused if we swap out self.socket while the
-        # fd is registered, so remove it now and re-register after
-        # wrap_socket().
-        self.io_loop.remove_handler(self.socket)
-        old_state = self._state
-        self._state = None
-        self.socket = ssl_wrap_socket(self.socket, self._ssl_options,
-                                      server_hostname=self._server_hostname,
-                                      do_handshake_on_connect=False)
-        self._add_io_state(old_state)
-
-    def wait_for_handshake(self, callback=None):
-        """Wait for the initial SSL handshake to complete.
-
-        If a ``callback`` is given, it will be called with no
-        arguments once the handshake is complete; otherwise this
-        method returns a `.Future` which will resolve to the
-        stream itself after the handshake is complete.
-
-        Once the handshake is complete, information such as
-        the peer's certificate and NPN/ALPN selections may be
-        accessed on ``self.socket``.
-
-        This method is intended for use on server-side streams
-        or after using `IOStream.start_tls`; it should not be used
-        with `IOStream.connect` (which already waits for the
-        handshake to complete). It may only be called once per stream.
-
-        .. versionadded:: 4.2
-        """
-        if (self._ssl_connect_callback is not None or
-                self._ssl_connect_future is not None):
-            raise RuntimeError("Already waiting")
-        if callback is not None:
-            self._ssl_connect_callback = stack_context.wrap(callback)
-            future = None
-        else:
-            future = self._ssl_connect_future = TracebackFuture()
-        if not self._ssl_accepting:
-            self._run_ssl_connect_callback()
-        return future
-
-    def write_to_fd(self, data):
-        try:
-            return self.socket.send(data)
-        except ssl.SSLError as e:
-            if e.args[0] == ssl.SSL_ERROR_WANT_WRITE:
-                # In Python 3.5+, SSLSocket.send raises a WANT_WRITE error if
-                # the socket is not writeable; we need to transform this into
-                # an EWOULDBLOCK socket.error or a zero return value,
-                # either of which will be recognized by the caller of this
-                # method. Prior to Python 3.5, an unwriteable socket would
-                # simply return 0 bytes written.
-                return 0
-            raise
-        finally:
-            # Avoid keeping to data, which can be a memoryview.
-            # See https://github.com/tornadoweb/tornado/pull/2008
-            del data
-
-    def read_from_fd(self):
-        if self._ssl_accepting:
-            # If the handshake hasn't finished yet, there can't be anything
-            # to read (attempting to read may or may not raise an exception
-            # depending on the SSL version)
-            return None
-        try:
-            # SSLSocket objects have both a read() and recv() method,
-            # while regular sockets only have recv().
-            # The recv() method blocks (at least in python 2.6) if it is
-            # called when there is nothing to read, so we have to use
-            # read() instead.
-            chunk = self.socket.read(self.read_chunk_size)
-        except ssl.SSLError as e:
-            # SSLError is a subclass of socket.error, so this except
-            # block must come first.
-            if e.args[0] == ssl.SSL_ERROR_WANT_READ:
-                return None
-            else:
-                raise
-        except socket.error as e:
-            if e.args[0] in _ERRNO_WOULDBLOCK:
-                return None
-            else:
-                raise
-        if not chunk:
-            self.close()
-            return None
-        return chunk
-
-    def _is_connreset(self, e):
-        if isinstance(e, ssl.SSLError) and e.args[0] == ssl.SSL_ERROR_EOF:
-            return True
-        return super(SSLIOStream, self)._is_connreset(e)
-
-
-class PipeIOStream(BaseIOStream):
-    """Pipe-based `IOStream` implementation.
-
-    The constructor takes an integer file descriptor (such as one returned
-    by `os.pipe`) rather than an open file object.  Pipes are generally
-    one-way, so a `PipeIOStream` can be used for reading or writing but not
-    both.
-    """
-    def __init__(self, fd, *args, **kwargs):
-        self.fd = fd
-        _set_nonblocking(fd)
-        super(PipeIOStream, self).__init__(*args, **kwargs)
-
-    def fileno(self):
-        return self.fd
-
-    def close_fd(self):
-        os.close(self.fd)
-
-    def write_to_fd(self, data):
-        try:
-            return os.write(self.fd, data)
-        finally:
-            # Avoid keeping to data, which can be a memoryview.
-            # See https://github.com/tornadoweb/tornado/pull/2008
-            del data
-
-    def read_from_fd(self):
-        try:
-            chunk = os.read(self.fd, self.read_chunk_size)
-        except (IOError, OSError) as e:
-            if errno_from_exception(e) in _ERRNO_WOULDBLOCK:
-                return None
-            elif errno_from_exception(e) == errno.EBADF:
-                # If the writing half of a pipe is closed, select will
-                # report it as readable but reads will fail with EBADF.
-                self.close(exc_info=True)
-                return None
-            else:
-                raise
-        if not chunk:
-            self.close()
-            return None
-        return chunk
-
-
-def doctests():
-    import doctest
-    return doctest.DocTestSuite()
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Utility classes to write to and read from non-blocking files and sockets. 
+ 
+Contents: 
+ 
+* `BaseIOStream`: Generic interface for reading and writing. 
+* `IOStream`: Implementation of BaseIOStream using non-blocking sockets. 
+* `SSLIOStream`: SSL-aware version of IOStream. 
+* `PipeIOStream`: Pipe-based IOStream implementation. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import collections 
+import errno 
+import numbers 
+import os 
+import socket 
+import sys 
+import re 
+ 
+from tornado.concurrent import TracebackFuture 
+from tornado import ioloop 
+from tornado.log import gen_log, app_log 
+from tornado.netutil import ssl_wrap_socket, ssl_match_hostname, SSLCertificateError, _client_ssl_defaults, _server_ssl_defaults 
+from tornado import stack_context 
+from tornado.util import errno_from_exception 
+ 
+try: 
+    from tornado.platform.posix import _set_nonblocking 
+except ImportError: 
+    _set_nonblocking = None 
+ 
+try: 
+    import ssl 
+except ImportError: 
+    # ssl is not available on Google App Engine 
+    ssl = None 
+ 
+# These errnos indicate that a non-blocking operation must be retried 
+# at a later time.  On most platforms they're the same value, but on 
+# some they differ. 
+_ERRNO_WOULDBLOCK = (errno.EWOULDBLOCK, errno.EAGAIN) 
+ 
+if hasattr(errno, "WSAEWOULDBLOCK"): 
+    _ERRNO_WOULDBLOCK += (errno.WSAEWOULDBLOCK,)  # type: ignore 
+ 
+# These errnos indicate that a connection has been abruptly terminated. 
+# They should be caught and handled less noisily than other errors. 
+_ERRNO_CONNRESET = (errno.ECONNRESET, errno.ECONNABORTED, errno.EPIPE, 
+                    errno.ETIMEDOUT) 
+ 
+if hasattr(errno, "WSAECONNRESET"): 
+    _ERRNO_CONNRESET += (errno.WSAECONNRESET, errno.WSAECONNABORTED, errno.WSAETIMEDOUT)  # type: ignore 
+ 
+if sys.platform == 'darwin': 
+    # OSX appears to have a race condition that causes send(2) to return 
+    # EPROTOTYPE if called while a socket is being torn down: 
+    # http://erickt.github.io/blog/2014/11/19/adventures-in-debugging-a-potential-osx-kernel-bug/ 
+    # Since the socket is being closed anyway, treat this as an ECONNRESET 
+    # instead of an unexpected error. 
+    _ERRNO_CONNRESET += (errno.EPROTOTYPE,)  # type: ignore 
+ 
+# More non-portable errnos: 
+_ERRNO_INPROGRESS = (errno.EINPROGRESS,) 
+ 
+if hasattr(errno, "WSAEINPROGRESS"): 
+    _ERRNO_INPROGRESS += (errno.WSAEINPROGRESS,)  # type: ignore 
+ 
+_WINDOWS = sys.platform.startswith('win') 
+ 
+ 
+class StreamClosedError(IOError): 
+    """Exception raised by `IOStream` methods when the stream is closed. 
+ 
+    Note that the close callback is scheduled to run *after* other 
+    callbacks on the stream (to allow for buffered data to be processed), 
+    so you may see this error before you see the close callback. 
+ 
+    The ``real_error`` attribute contains the underlying error that caused 
+    the stream to close (if any). 
+ 
+    .. versionchanged:: 4.3 
+       Added the ``real_error`` attribute. 
+    """ 
+    def __init__(self, real_error=None): 
+        super(StreamClosedError, self).__init__('Stream is closed') 
+        self.real_error = real_error 
+ 
+ 
+class UnsatisfiableReadError(Exception): 
+    """Exception raised when a read cannot be satisfied. 
+ 
+    Raised by ``read_until`` and ``read_until_regex`` with a ``max_bytes`` 
+    argument. 
+    """ 
+    pass 
+ 
+ 
+class StreamBufferFullError(Exception): 
+    """Exception raised by `IOStream` methods when the buffer is full. 
+    """ 
+ 
+ 
+class BaseIOStream(object): 
+    """A utility class to write to and read from a non-blocking file or socket. 
+ 
+    We support a non-blocking ``write()`` and a family of ``read_*()`` methods. 
+    All of the methods take an optional ``callback`` argument and return a 
+    `.Future` only if no callback is given.  When the operation completes, 
+    the callback will be run or the `.Future` will resolve with the data 
+    read (or ``None`` for ``write()``).  All outstanding ``Futures`` will 
+    resolve with a `StreamClosedError` when the stream is closed; users 
+    of the callback interface will be notified via 
+    `.BaseIOStream.set_close_callback` instead. 
+ 
+    When a stream is closed due to an error, the IOStream's ``error`` 
+    attribute contains the exception object. 
+ 
+    Subclasses must implement `fileno`, `close_fd`, `write_to_fd`, 
+    `read_from_fd`, and optionally `get_fd_error`. 
+    """ 
+    def __init__(self, io_loop=None, max_buffer_size=None, 
+                 read_chunk_size=None, max_write_buffer_size=None): 
+        """`BaseIOStream` constructor. 
+ 
+        :arg io_loop: The `.IOLoop` to use; defaults to `.IOLoop.current`. 
+                      Deprecated since Tornado 4.1. 
+        :arg max_buffer_size: Maximum amount of incoming data to buffer; 
+            defaults to 100MB. 
+        :arg read_chunk_size: Amount of data to read at one time from the 
+            underlying transport; defaults to 64KB. 
+        :arg max_write_buffer_size: Amount of outgoing data to buffer; 
+            defaults to unlimited. 
+ 
+        .. versionchanged:: 4.0 
+           Add the ``max_write_buffer_size`` parameter.  Changed default 
+           ``read_chunk_size`` to 64KB. 
+        """ 
+        self.io_loop = io_loop or ioloop.IOLoop.current() 
+        self.max_buffer_size = max_buffer_size or 104857600 
+        # A chunk size that is too close to max_buffer_size can cause 
+        # spurious failures. 
+        self.read_chunk_size = min(read_chunk_size or 65536, 
+                                   self.max_buffer_size // 2) 
+        self.max_write_buffer_size = max_write_buffer_size 
+        self.error = None 
+        self._read_buffer = bytearray() 
+        self._read_buffer_pos = 0 
+        self._read_buffer_size = 0 
+        self._write_buffer = bytearray() 
+        self._write_buffer_pos = 0 
+        self._write_buffer_size = 0 
+        self._write_buffer_frozen = False 
+        self._total_write_index = 0 
+        self._total_write_done_index = 0 
+        self._pending_writes_while_frozen = [] 
+        self._read_delimiter = None 
+        self._read_regex = None 
+        self._read_max_bytes = None 
+        self._read_bytes = None 
+        self._read_partial = False 
+        self._read_until_close = False 
+        self._read_callback = None 
+        self._read_future = None 
+        self._streaming_callback = None 
+        self._write_callback = None 
+        self._write_futures = collections.deque() 
+        self._close_callback = None 
+        self._connect_callback = None 
+        self._connect_future = None 
+        # _ssl_connect_future should be defined in SSLIOStream 
+        # but it's here so we can clean it up in maybe_run_close_callback. 
+        # TODO: refactor that so subclasses can add additional futures 
+        # to be cancelled. 
+        self._ssl_connect_future = None 
+        self._connecting = False 
+        self._state = None 
+        self._pending_callbacks = 0 
+        self._closed = False 
+ 
+    def fileno(self): 
+        """Returns the file descriptor for this stream.""" 
+        raise NotImplementedError() 
+ 
+    def close_fd(self): 
+        """Closes the file underlying this stream. 
+ 
+        ``close_fd`` is called by `BaseIOStream` and should not be called 
+        elsewhere; other users should call `close` instead. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def write_to_fd(self, data): 
+        """Attempts to write ``data`` to the underlying file. 
+ 
+        Returns the number of bytes written. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def read_from_fd(self): 
+        """Attempts to read from the underlying file. 
+ 
+        Returns ``None`` if there was nothing to read (the socket 
+        returned `~errno.EWOULDBLOCK` or equivalent), otherwise 
+        returns the data.  When possible, should return no more than 
+        ``self.read_chunk_size`` bytes at a time. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def get_fd_error(self): 
+        """Returns information about any error on the underlying file. 
+ 
+        This method is called after the `.IOLoop` has signaled an error on the 
+        file descriptor, and should return an Exception (such as `socket.error` 
+        with additional information, or None if no such information is 
+        available. 
+        """ 
+        return None 
+ 
+    def read_until_regex(self, regex, callback=None, max_bytes=None): 
+        """Asynchronously read until we have matched the given regex. 
+ 
+        The result includes the data that matches the regex and anything 
+        that came before it.  If a callback is given, it will be run 
+        with the data as an argument; if not, this method returns a 
+        `.Future`. 
+ 
+        If ``max_bytes`` is not None, the connection will be closed 
+        if more than ``max_bytes`` bytes have been read and the regex is 
+        not satisfied. 
+ 
+        .. versionchanged:: 4.0 
+            Added the ``max_bytes`` argument.  The ``callback`` argument is 
+            now optional and a `.Future` will be returned if it is omitted. 
+        """ 
+        future = self._set_read_callback(callback) 
+        self._read_regex = re.compile(regex) 
+        self._read_max_bytes = max_bytes 
+        try: 
+            self._try_inline_read() 
+        except UnsatisfiableReadError as e: 
+            # Handle this the same way as in _handle_events. 
+            gen_log.info("Unsatisfiable read, closing connection: %s" % e) 
+            self.close(exc_info=True) 
+            return future 
+        except: 
+            if future is not None: 
+                # Ensure that the future doesn't log an error because its 
+                # failure was never examined. 
+                future.add_done_callback(lambda f: f.exception()) 
+            raise 
+        return future 
+ 
+    def read_until(self, delimiter, callback=None, max_bytes=None): 
+        """Asynchronously read until we have found the given delimiter. 
+ 
+        The result includes all the data read including the delimiter. 
+        If a callback is given, it will be run with the data as an argument; 
+        if not, this method returns a `.Future`. 
+ 
+        If ``max_bytes`` is not None, the connection will be closed 
+        if more than ``max_bytes`` bytes have been read and the delimiter 
+        is not found. 
+ 
+        .. versionchanged:: 4.0 
+            Added the ``max_bytes`` argument.  The ``callback`` argument is 
+            now optional and a `.Future` will be returned if it is omitted. 
+        """ 
+        future = self._set_read_callback(callback) 
+        self._read_delimiter = delimiter 
+        self._read_max_bytes = max_bytes 
+        try: 
+            self._try_inline_read() 
+        except UnsatisfiableReadError as e: 
+            # Handle this the same way as in _handle_events. 
+            gen_log.info("Unsatisfiable read, closing connection: %s" % e) 
+            self.close(exc_info=True) 
+            return future 
+        except: 
+            if future is not None: 
+                future.add_done_callback(lambda f: f.exception()) 
+            raise 
+        return future 
+ 
+    def read_bytes(self, num_bytes, callback=None, streaming_callback=None, 
+                   partial=False): 
+        """Asynchronously read a number of bytes. 
+ 
+        If a ``streaming_callback`` is given, it will be called with chunks 
+        of data as they become available, and the final result will be empty. 
+        Otherwise, the result is all the data that was read. 
+        If a callback is given, it will be run with the data as an argument; 
+        if not, this method returns a `.Future`. 
+ 
+        If ``partial`` is true, the callback is run as soon as we have 
+        any bytes to return (but never more than ``num_bytes``) 
+ 
+        .. versionchanged:: 4.0 
+            Added the ``partial`` argument.  The callback argument is now 
+            optional and a `.Future` will be returned if it is omitted. 
+        """ 
+        future = self._set_read_callback(callback) 
+        assert isinstance(num_bytes, numbers.Integral) 
+        self._read_bytes = num_bytes 
+        self._read_partial = partial 
+        self._streaming_callback = stack_context.wrap(streaming_callback) 
+        try: 
+            self._try_inline_read() 
+        except: 
+            if future is not None: 
+                future.add_done_callback(lambda f: f.exception()) 
+            raise 
+        return future 
+ 
+    def read_until_close(self, callback=None, streaming_callback=None): 
+        """Asynchronously reads all data from the socket until it is closed. 
+ 
+        If a ``streaming_callback`` is given, it will be called with chunks 
+        of data as they become available, and the final result will be empty. 
+        Otherwise, the result is all the data that was read. 
+        If a callback is given, it will be run with the data as an argument; 
+        if not, this method returns a `.Future`. 
+ 
+        Note that if a ``streaming_callback`` is used, data will be 
+        read from the socket as quickly as it becomes available; there 
+        is no way to apply backpressure or cancel the reads. If flow 
+        control or cancellation are desired, use a loop with 
+        `read_bytes(partial=True) <.read_bytes>` instead. 
+ 
+        .. versionchanged:: 4.0 
+            The callback argument is now optional and a `.Future` will 
+            be returned if it is omitted. 
+ 
+        """ 
+        future = self._set_read_callback(callback) 
+        self._streaming_callback = stack_context.wrap(streaming_callback) 
+        if self.closed(): 
+            if self._streaming_callback is not None: 
+                self._run_read_callback(self._read_buffer_size, True) 
+            self._run_read_callback(self._read_buffer_size, False) 
+            return future 
+        self._read_until_close = True 
+        try: 
+            self._try_inline_read() 
+        except: 
+            if future is not None: 
+                future.add_done_callback(lambda f: f.exception()) 
+            raise 
+        return future 
+ 
+    def write(self, data, callback=None): 
+        """Asynchronously write the given data to this stream. 
+ 
+        If ``callback`` is given, we call it when all of the buffered write 
+        data has been successfully written to the stream. If there was 
+        previously buffered write data and an old write callback, that 
+        callback is simply overwritten with this new callback. 
+ 
+        If no ``callback`` is given, this method returns a `.Future` that 
+        resolves (with a result of ``None``) when the write has been 
+        completed. 
+ 
+        The ``data`` argument may be of type `bytes` or `memoryview`. 
+ 
+        .. versionchanged:: 4.0 
+            Now returns a `.Future` if no callback is given. 
+ 
+        .. versionchanged:: 4.5 
+            Added support for `memoryview` arguments. 
+        """ 
+        self._check_closed() 
+        if data: 
+            if (self.max_write_buffer_size is not None and 
+                    self._write_buffer_size + len(data) > self.max_write_buffer_size): 
+                raise StreamBufferFullError("Reached maximum write buffer size") 
+            if self._write_buffer_frozen: 
+                self._pending_writes_while_frozen.append(data) 
+            else: 
+                self._write_buffer += data 
+                self._write_buffer_size += len(data) 
+            self._total_write_index += len(data) 
+        if callback is not None: 
+            self._write_callback = stack_context.wrap(callback) 
+            future = None 
+        else: 
+            future = TracebackFuture() 
+            future.add_done_callback(lambda f: f.exception()) 
+            self._write_futures.append((self._total_write_index, future)) 
+        if not self._connecting: 
+            self._handle_write() 
+            if self._write_buffer_size: 
+                self._add_io_state(self.io_loop.WRITE) 
+            self._maybe_add_error_listener() 
+        return future 
+ 
+    def set_close_callback(self, callback): 
+        """Call the given callback when the stream is closed. 
+ 
+        This is not necessary for applications that use the `.Future` 
+        interface; all outstanding ``Futures`` will resolve with a 
+        `StreamClosedError` when the stream is closed. 
+        """ 
+        self._close_callback = stack_context.wrap(callback) 
+        self._maybe_add_error_listener() 
+ 
+    def close(self, exc_info=False): 
+        """Close this stream. 
+ 
+        If ``exc_info`` is true, set the ``error`` attribute to the current 
+        exception from `sys.exc_info` (or if ``exc_info`` is a tuple, 
+        use that instead of `sys.exc_info`). 
+        """ 
+        if not self.closed(): 
+            if exc_info: 
+                if not isinstance(exc_info, tuple): 
+                    exc_info = sys.exc_info() 
+                if any(exc_info): 
+                    self.error = exc_info[1] 
+            if self._read_until_close: 
+                if (self._streaming_callback is not None and 
+                        self._read_buffer_size): 
+                    self._run_read_callback(self._read_buffer_size, True) 
+                self._read_until_close = False 
+                self._run_read_callback(self._read_buffer_size, False) 
+            if self._state is not None: 
+                self.io_loop.remove_handler(self.fileno()) 
+                self._state = None 
+            self.close_fd() 
+            self._closed = True 
+        self._maybe_run_close_callback() 
+ 
+    def _maybe_run_close_callback(self): 
+        # If there are pending callbacks, don't run the close callback 
+        # until they're done (see _maybe_add_error_handler) 
+        if self.closed() and self._pending_callbacks == 0: 
+            futures = [] 
+            if self._read_future is not None: 
+                futures.append(self._read_future) 
+                self._read_future = None 
+            futures += [future for _, future in self._write_futures] 
+            self._write_futures.clear() 
+            if self._connect_future is not None: 
+                futures.append(self._connect_future) 
+                self._connect_future = None 
+            if self._ssl_connect_future is not None: 
+                futures.append(self._ssl_connect_future) 
+                self._ssl_connect_future = None 
+            for future in futures: 
+                future.set_exception(StreamClosedError(real_error=self.error)) 
+            if self._close_callback is not None: 
+                cb = self._close_callback 
+                self._close_callback = None 
+                self._run_callback(cb) 
+            # Delete any unfinished callbacks to break up reference cycles. 
+            self._read_callback = self._write_callback = None 
+            # Clear the buffers so they can be cleared immediately even 
+            # if the IOStream object is kept alive by a reference cycle. 
+            # TODO: Clear the read buffer too; it currently breaks some tests. 
+            self._write_buffer = None 
+            self._write_buffer_size = 0 
+ 
+    def reading(self): 
+        """Returns true if we are currently reading from the stream.""" 
+        return self._read_callback is not None or self._read_future is not None 
+ 
+    def writing(self): 
+        """Returns true if we are currently writing to the stream.""" 
+        return self._write_buffer_size > 0 
+ 
+    def closed(self): 
+        """Returns true if the stream has been closed.""" 
+        return self._closed 
+ 
+    def set_nodelay(self, value): 
+        """Sets the no-delay flag for this stream. 
+ 
+        By default, data written to TCP streams may be held for a time 
+        to make the most efficient use of bandwidth (according to 
+        Nagle's algorithm).  The no-delay flag requests that data be 
+        written as soon as possible, even if doing so would consume 
+        additional bandwidth. 
+ 
+        This flag is currently defined only for TCP-based ``IOStreams``. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        pass 
+ 
+    def _handle_events(self, fd, events): 
+        if self.closed(): 
+            gen_log.warning("Got events for closed stream %s", fd) 
+            return 
+        try: 
+            if self._connecting: 
+                # Most IOLoops will report a write failed connect 
+                # with the WRITE event, but SelectIOLoop reports a 
+                # READ as well so we must check for connecting before 
+                # either. 
+                self._handle_connect() 
+            if self.closed(): 
+                return 
+            if events & self.io_loop.READ: 
+                self._handle_read() 
+            if self.closed(): 
+                return 
+            if events & self.io_loop.WRITE: 
+                self._handle_write() 
+            if self.closed(): 
+                return 
+            if events & self.io_loop.ERROR: 
+                self.error = self.get_fd_error() 
+                # We may have queued up a user callback in _handle_read or 
+                # _handle_write, so don't close the IOStream until those 
+                # callbacks have had a chance to run. 
+                self.io_loop.add_callback(self.close) 
+                return 
+            state = self.io_loop.ERROR 
+            if self.reading(): 
+                state |= self.io_loop.READ 
+            if self.writing(): 
+                state |= self.io_loop.WRITE 
+            if state == self.io_loop.ERROR and self._read_buffer_size == 0: 
+                # If the connection is idle, listen for reads too so 
+                # we can tell if the connection is closed.  If there is 
+                # data in the read buffer we won't run the close callback 
+                # yet anyway, so we don't need to listen in this case. 
+                state |= self.io_loop.READ 
+            if state != self._state: 
+                assert self._state is not None, \ 
+                    "shouldn't happen: _handle_events without self._state" 
+                self._state = state 
+                self.io_loop.update_handler(self.fileno(), self._state) 
+        except UnsatisfiableReadError as e: 
+            gen_log.info("Unsatisfiable read, closing connection: %s" % e) 
+            self.close(exc_info=True) 
+        except Exception: 
+            gen_log.error("Uncaught exception, closing connection.", 
+                          exc_info=True) 
+            self.close(exc_info=True) 
+            raise 
+ 
+    def _run_callback(self, callback, *args): 
+        def wrapper(): 
+            self._pending_callbacks -= 1 
+            try: 
+                return callback(*args) 
+            except Exception: 
+                app_log.error("Uncaught exception, closing connection.", 
+                              exc_info=True) 
+                # Close the socket on an uncaught exception from a user callback 
+                # (It would eventually get closed when the socket object is 
+                # gc'd, but we don't want to rely on gc happening before we 
+                # run out of file descriptors) 
+                self.close(exc_info=True) 
+                # Re-raise the exception so that IOLoop.handle_callback_exception 
+                # can see it and log the error 
+                raise 
+            finally: 
+                self._maybe_add_error_listener() 
+        # We schedule callbacks to be run on the next IOLoop iteration 
+        # rather than running them directly for several reasons: 
+        # * Prevents unbounded stack growth when a callback calls an 
+        #   IOLoop operation that immediately runs another callback 
+        # * Provides a predictable execution context for e.g. 
+        #   non-reentrant mutexes 
+        # * Ensures that the try/except in wrapper() is run outside 
+        #   of the application's StackContexts 
+        with stack_context.NullContext(): 
+            # stack_context was already captured in callback, we don't need to 
+            # capture it again for IOStream's wrapper.  This is especially 
+            # important if the callback was pre-wrapped before entry to 
+            # IOStream (as in HTTPConnection._header_callback), as we could 
+            # capture and leak the wrong context here. 
+            self._pending_callbacks += 1 
+            self.io_loop.add_callback(wrapper) 
+ 
+    def _read_to_buffer_loop(self): 
+        # This method is called from _handle_read and _try_inline_read. 
+        try: 
+            if self._read_bytes is not None: 
+                target_bytes = self._read_bytes 
+            elif self._read_max_bytes is not None: 
+                target_bytes = self._read_max_bytes 
+            elif self.reading(): 
+                # For read_until without max_bytes, or 
+                # read_until_close, read as much as we can before 
+                # scanning for the delimiter. 
+                target_bytes = None 
+            else: 
+                target_bytes = 0 
+            next_find_pos = 0 
+            # Pretend to have a pending callback so that an EOF in 
+            # _read_to_buffer doesn't trigger an immediate close 
+            # callback.  At the end of this method we'll either 
+            # establish a real pending callback via 
+            # _read_from_buffer or run the close callback. 
+            # 
+            # We need two try statements here so that 
+            # pending_callbacks is decremented before the `except` 
+            # clause below (which calls `close` and does need to 
+            # trigger the callback) 
+            self._pending_callbacks += 1 
+            while not self.closed(): 
+                # Read from the socket until we get EWOULDBLOCK or equivalent. 
+                # SSL sockets do some internal buffering, and if the data is 
+                # sitting in the SSL object's buffer select() and friends 
+                # can't see it; the only way to find out if it's there is to 
+                # try to read it. 
+                if self._read_to_buffer() == 0: 
+                    break 
+ 
+                self._run_streaming_callback() 
+ 
+                # If we've read all the bytes we can use, break out of 
+                # this loop.  We can't just call read_from_buffer here 
+                # because of subtle interactions with the 
+                # pending_callback and error_listener mechanisms. 
+                # 
+                # If we've reached target_bytes, we know we're done. 
+                if (target_bytes is not None and 
+                        self._read_buffer_size >= target_bytes): 
+                    break 
+ 
+                # Otherwise, we need to call the more expensive find_read_pos. 
+                # It's inefficient to do this on every read, so instead 
+                # do it on the first read and whenever the read buffer 
+                # size has doubled. 
+                if self._read_buffer_size >= next_find_pos: 
+                    pos = self._find_read_pos() 
+                    if pos is not None: 
+                        return pos 
+                    next_find_pos = self._read_buffer_size * 2 
+            return self._find_read_pos() 
+        finally: 
+            self._pending_callbacks -= 1 
+ 
+    def _handle_read(self): 
+        try: 
+            pos = self._read_to_buffer_loop() 
+        except UnsatisfiableReadError: 
+            raise 
+        except Exception as e: 
+            gen_log.warning("error on read: %s" % e) 
+            self.close(exc_info=True) 
+            return 
+        if pos is not None: 
+            self._read_from_buffer(pos) 
+            return 
+        else: 
+            self._maybe_run_close_callback() 
+ 
+    def _set_read_callback(self, callback): 
+        assert self._read_callback is None, "Already reading" 
+        assert self._read_future is None, "Already reading" 
+        if callback is not None: 
+            self._read_callback = stack_context.wrap(callback) 
+        else: 
+            self._read_future = TracebackFuture() 
+        return self._read_future 
+ 
+    def _run_read_callback(self, size, streaming): 
+        if streaming: 
+            callback = self._streaming_callback 
+        else: 
+            callback = self._read_callback 
+            self._read_callback = self._streaming_callback = None 
+            if self._read_future is not None: 
+                assert callback is None 
+                future = self._read_future 
+                self._read_future = None 
+                future.set_result(self._consume(size)) 
+        if callback is not None: 
+            assert (self._read_future is None) or streaming 
+            self._run_callback(callback, self._consume(size)) 
+        else: 
+            # If we scheduled a callback, we will add the error listener 
+            # afterwards.  If we didn't, we have to do it now. 
+            self._maybe_add_error_listener() 
+ 
+    def _try_inline_read(self): 
+        """Attempt to complete the current read operation from buffered data. 
+ 
+        If the read can be completed without blocking, schedules the 
+        read callback on the next IOLoop iteration; otherwise starts 
+        listening for reads on the socket. 
+        """ 
+        # See if we've already got the data from a previous read 
+        self._run_streaming_callback() 
+        pos = self._find_read_pos() 
+        if pos is not None: 
+            self._read_from_buffer(pos) 
+            return 
+        self._check_closed() 
+        try: 
+            pos = self._read_to_buffer_loop() 
+        except Exception: 
+            # If there was an in _read_to_buffer, we called close() already, 
+            # but couldn't run the close callback because of _pending_callbacks. 
+            # Before we escape from this function, run the close callback if 
+            # applicable. 
+            self._maybe_run_close_callback() 
+            raise 
+        if pos is not None: 
+            self._read_from_buffer(pos) 
+            return 
+        # We couldn't satisfy the read inline, so either close the stream 
+        # or listen for new data. 
+        if self.closed(): 
+            self._maybe_run_close_callback() 
+        else: 
+            self._add_io_state(ioloop.IOLoop.READ) 
+ 
+    def _read_to_buffer(self): 
+        """Reads from the socket and appends the result to the read buffer. 
+ 
+        Returns the number of bytes read.  Returns 0 if there is nothing 
+        to read (i.e. the read returns EWOULDBLOCK or equivalent).  On 
+        error closes the socket and raises an exception. 
+        """ 
+        while True: 
+            try: 
+                chunk = self.read_from_fd() 
+            except (socket.error, IOError, OSError) as e: 
+                if errno_from_exception(e) == errno.EINTR: 
+                    continue 
+                # ssl.SSLError is a subclass of socket.error 
+                if self._is_connreset(e): 
+                    # Treat ECONNRESET as a connection close rather than 
+                    # an error to minimize log spam  (the exception will 
+                    # be available on self.error for apps that care). 
+                    self.close(exc_info=True) 
+                    return 
+                self.close(exc_info=True) 
+                raise 
+            break 
+        if chunk is None: 
+            return 0 
+        self._read_buffer += chunk 
+        self._read_buffer_size += len(chunk) 
+        if self._read_buffer_size > self.max_buffer_size: 
+            gen_log.error("Reached maximum read buffer size") 
+            self.close() 
+            raise StreamBufferFullError("Reached maximum read buffer size") 
+        return len(chunk) 
+ 
+    def _run_streaming_callback(self): 
+        if self._streaming_callback is not None and self._read_buffer_size: 
+            bytes_to_consume = self._read_buffer_size 
+            if self._read_bytes is not None: 
+                bytes_to_consume = min(self._read_bytes, bytes_to_consume) 
+                self._read_bytes -= bytes_to_consume 
+            self._run_read_callback(bytes_to_consume, True) 
+ 
+    def _read_from_buffer(self, pos): 
+        """Attempts to complete the currently-pending read from the buffer. 
+ 
+        The argument is either a position in the read buffer or None, 
+        as returned by _find_read_pos. 
+        """ 
+        self._read_bytes = self._read_delimiter = self._read_regex = None 
+        self._read_partial = False 
+        self._run_read_callback(pos, False) 
+ 
+    def _find_read_pos(self): 
+        """Attempts to find a position in the read buffer that satisfies 
+        the currently-pending read. 
+ 
+        Returns a position in the buffer if the current read can be satisfied, 
+        or None if it cannot. 
+        """ 
+        if (self._read_bytes is not None and 
+            (self._read_buffer_size >= self._read_bytes or 
+             (self._read_partial and self._read_buffer_size > 0))): 
+            num_bytes = min(self._read_bytes, self._read_buffer_size) 
+            return num_bytes 
+        elif self._read_delimiter is not None: 
+            # Multi-byte delimiters (e.g. '\r\n') may straddle two 
+            # chunks in the read buffer, so we can't easily find them 
+            # without collapsing the buffer.  However, since protocols 
+            # using delimited reads (as opposed to reads of a known 
+            # length) tend to be "line" oriented, the delimiter is likely 
+            # to be in the first few chunks.  Merge the buffer gradually 
+            # since large merges are relatively expensive and get undone in 
+            # _consume(). 
+            if self._read_buffer: 
+                loc = self._read_buffer.find(self._read_delimiter, 
+                                             self._read_buffer_pos) 
+                if loc != -1: 
+                    loc -= self._read_buffer_pos 
+                    delimiter_len = len(self._read_delimiter) 
+                    self._check_max_bytes(self._read_delimiter, 
+                                          loc + delimiter_len) 
+                    return loc + delimiter_len 
+                self._check_max_bytes(self._read_delimiter, 
+                                      self._read_buffer_size) 
+        elif self._read_regex is not None: 
+            if self._read_buffer: 
+                m = self._read_regex.search(self._read_buffer, 
+                                            self._read_buffer_pos) 
+                if m is not None: 
+                    loc = m.end() - self._read_buffer_pos 
+                    self._check_max_bytes(self._read_regex, loc) 
+                    return loc 
+                self._check_max_bytes(self._read_regex, self._read_buffer_size) 
+        return None 
+ 
+    def _check_max_bytes(self, delimiter, size): 
+        if (self._read_max_bytes is not None and 
+                size > self._read_max_bytes): 
+            raise UnsatisfiableReadError( 
+                "delimiter %r not found within %d bytes" % ( 
+                    delimiter, self._read_max_bytes)) 
+ 
+    def _freeze_write_buffer(self, size): 
+        self._write_buffer_frozen = size 
+ 
+    def _unfreeze_write_buffer(self): 
+        self._write_buffer_frozen = False 
+        self._write_buffer += b''.join(self._pending_writes_while_frozen) 
+        self._write_buffer_size += sum(map(len, self._pending_writes_while_frozen)) 
+        self._pending_writes_while_frozen[:] = [] 
+ 
+    def _got_empty_write(self, size): 
+        """ 
+        Called when a non-blocking write() failed writing anything. 
+        Can be overridden in subclasses. 
+        """ 
+ 
+    def _handle_write(self): 
+        while self._write_buffer_size: 
+            assert self._write_buffer_size >= 0 
+            try: 
+                start = self._write_buffer_pos 
+                if self._write_buffer_frozen: 
+                    size = self._write_buffer_frozen 
+                elif _WINDOWS: 
+                    # On windows, socket.send blows up if given a 
+                    # write buffer that's too large, instead of just 
+                    # returning the number of bytes it was able to 
+                    # process.  Therefore we must not call socket.send 
+                    # with more than 128KB at a time. 
+                    size = 128 * 1024 
+                else: 
+                    size = self._write_buffer_size 
+                num_bytes = self.write_to_fd( 
+                    memoryview(self._write_buffer)[start:start + size]) 
+                if num_bytes == 0: 
+                    self._got_empty_write(size) 
+                    break 
+                self._write_buffer_pos += num_bytes 
+                self._write_buffer_size -= num_bytes 
+                # Amortized O(1) shrink 
+                # (this heuristic is implemented natively in Python 3.4+ 
+                #  but is replicated here for Python 2) 
+                if self._write_buffer_pos > self._write_buffer_size: 
+                    del self._write_buffer[:self._write_buffer_pos] 
+                    self._write_buffer_pos = 0 
+                if self._write_buffer_frozen: 
+                    self._unfreeze_write_buffer() 
+                self._total_write_done_index += num_bytes 
+            except (socket.error, IOError, OSError) as e: 
+                if e.args[0] in _ERRNO_WOULDBLOCK: 
+                    self._got_empty_write(size) 
+                    break 
+                else: 
+                    if not self._is_connreset(e): 
+                        # Broken pipe errors are usually caused by connection 
+                        # reset, and its better to not log EPIPE errors to 
+                        # minimize log spam 
+                        gen_log.warning("Write error on %s: %s", 
+                                        self.fileno(), e) 
+                    self.close(exc_info=True) 
+                    return 
+ 
+        while self._write_futures: 
+            index, future = self._write_futures[0] 
+            if index > self._total_write_done_index: 
+                break 
+            self._write_futures.popleft() 
+            future.set_result(None) 
+ 
+        if not self._write_buffer_size: 
+            if self._write_callback: 
+                callback = self._write_callback 
+                self._write_callback = None 
+                self._run_callback(callback) 
+ 
+    def _consume(self, loc): 
+        # Consume loc bytes from the read buffer and return them 
+        if loc == 0: 
+            return b"" 
+        assert loc <= self._read_buffer_size 
+        # Slice the bytearray buffer into bytes, without intermediate copying 
+        b = (memoryview(self._read_buffer) 
+             [self._read_buffer_pos:self._read_buffer_pos + loc] 
+             ).tobytes() 
+        self._read_buffer_pos += loc 
+        self._read_buffer_size -= loc 
+        # Amortized O(1) shrink 
+        # (this heuristic is implemented natively in Python 3.4+ 
+        #  but is replicated here for Python 2) 
+        if self._read_buffer_pos > self._read_buffer_size: 
+            del self._read_buffer[:self._read_buffer_pos] 
+            self._read_buffer_pos = 0 
+        return b 
+ 
+    def _check_closed(self): 
+        if self.closed(): 
+            raise StreamClosedError(real_error=self.error) 
+ 
+    def _maybe_add_error_listener(self): 
+        # This method is part of an optimization: to detect a connection that 
+        # is closed when we're not actively reading or writing, we must listen 
+        # for read events.  However, it is inefficient to do this when the 
+        # connection is first established because we are going to read or write 
+        # immediately anyway.  Instead, we insert checks at various times to 
+        # see if the connection is idle and add the read listener then. 
+        if self._pending_callbacks != 0: 
+            return 
+        if self._state is None or self._state == ioloop.IOLoop.ERROR: 
+            if self.closed(): 
+                self._maybe_run_close_callback() 
+            elif (self._read_buffer_size == 0 and 
+                  self._close_callback is not None): 
+                self._add_io_state(ioloop.IOLoop.READ) 
+ 
+    def _add_io_state(self, state): 
+        """Adds `state` (IOLoop.{READ,WRITE} flags) to our event handler. 
+ 
+        Implementation notes: Reads and writes have a fast path and a 
+        slow path.  The fast path reads synchronously from socket 
+        buffers, while the slow path uses `_add_io_state` to schedule 
+        an IOLoop callback.  Note that in both cases, the callback is 
+        run asynchronously with `_run_callback`. 
+ 
+        To detect closed connections, we must have called 
+        `_add_io_state` at some point, but we want to delay this as 
+        much as possible so we don't have to set an `IOLoop.ERROR` 
+        listener that will be overwritten by the next slow-path 
+        operation.  As long as there are callbacks scheduled for 
+        fast-path ops, those callbacks may do more reads. 
+        If a sequence of fast-path ops do not end in a slow-path op, 
+        (e.g. for an @asynchronous long-poll request), we must add 
+        the error handler.  This is done in `_run_callback` and `write` 
+        (since the write callback is optional so we can have a 
+        fast-path write with no `_run_callback`) 
+        """ 
+        if self.closed(): 
+            # connection has been closed, so there can be no future events 
+            return 
+        if self._state is None: 
+            self._state = ioloop.IOLoop.ERROR | state 
+            with stack_context.NullContext(): 
+                self.io_loop.add_handler( 
+                    self.fileno(), self._handle_events, self._state) 
+        elif not self._state & state: 
+            self._state = self._state | state 
+            self.io_loop.update_handler(self.fileno(), self._state) 
+ 
+    def _is_connreset(self, exc): 
+        """Return true if exc is ECONNRESET or equivalent. 
+ 
+        May be overridden in subclasses. 
+        """ 
+        return (isinstance(exc, (socket.error, IOError)) and 
+                errno_from_exception(exc) in _ERRNO_CONNRESET) 
+ 
+ 
+class IOStream(BaseIOStream): 
+    r"""Socket-based `IOStream` implementation. 
+ 
+    This class supports the read and write methods from `BaseIOStream` 
+    plus a `connect` method. 
+ 
+    The ``socket`` parameter may either be connected or unconnected. 
+    For server operations the socket is the result of calling 
+    `socket.accept <socket.socket.accept>`.  For client operations the 
+    socket is created with `socket.socket`, and may either be 
+    connected before passing it to the `IOStream` or connected with 
+    `IOStream.connect`. 
+ 
+    A very simple (and broken) HTTP client using this class: 
+ 
+    .. testcode:: 
+ 
+        import tornado.ioloop 
+        import tornado.iostream 
+        import socket 
+ 
+        def send_request(): 
+            stream.write(b"GET / HTTP/1.0\r\nHost: friendfeed.com\r\n\r\n") 
+            stream.read_until(b"\r\n\r\n", on_headers) 
+ 
+        def on_headers(data): 
+            headers = {} 
+            for line in data.split(b"\r\n"): 
+               parts = line.split(b":") 
+               if len(parts) == 2: 
+                   headers[parts[0].strip()] = parts[1].strip() 
+            stream.read_bytes(int(headers[b"Content-Length"]), on_body) 
+ 
+        def on_body(data): 
+            print(data) 
+            stream.close() 
+            tornado.ioloop.IOLoop.current().stop() 
+ 
+        if __name__ == '__main__': 
+            s = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) 
+            stream = tornado.iostream.IOStream(s) 
+            stream.connect(("friendfeed.com", 80), send_request) 
+            tornado.ioloop.IOLoop.current().start() 
+ 
+    .. testoutput:: 
+       :hide: 
+ 
+    """ 
+    def __init__(self, socket, *args, **kwargs): 
+        self.socket = socket 
+        self.socket.setblocking(False) 
+        super(IOStream, self).__init__(*args, **kwargs) 
+ 
+    def fileno(self): 
+        return self.socket 
+ 
+    def close_fd(self): 
+        self.socket.close() 
+        self.socket = None 
+ 
+    def get_fd_error(self): 
+        errno = self.socket.getsockopt(socket.SOL_SOCKET, 
+                                       socket.SO_ERROR) 
+        return socket.error(errno, os.strerror(errno)) 
+ 
+    def read_from_fd(self): 
+        try: 
+            chunk = self.socket.recv(self.read_chunk_size) 
+        except socket.error as e: 
+            if e.args[0] in _ERRNO_WOULDBLOCK: 
+                return None 
+            else: 
+                raise 
+        if not chunk: 
+            self.close() 
+            return None 
+        return chunk 
+ 
+    def write_to_fd(self, data): 
+        try: 
+            return self.socket.send(data) 
+        finally: 
+            # Avoid keeping to data, which can be a memoryview. 
+            # See https://github.com/tornadoweb/tornado/pull/2008 
+            del data 
+ 
+    def connect(self, address, callback=None, server_hostname=None): 
+        """Connects the socket to a remote address without blocking. 
+ 
+        May only be called if the socket passed to the constructor was 
+        not previously connected.  The address parameter is in the 
+        same format as for `socket.connect <socket.socket.connect>` for 
+        the type of socket passed to the IOStream constructor, 
+        e.g. an ``(ip, port)`` tuple.  Hostnames are accepted here, 
+        but will be resolved synchronously and block the IOLoop. 
+        If you have a hostname instead of an IP address, the `.TCPClient` 
+        class is recommended instead of calling this method directly. 
+        `.TCPClient` will do asynchronous DNS resolution and handle 
+        both IPv4 and IPv6. 
+ 
+        If ``callback`` is specified, it will be called with no 
+        arguments when the connection is completed; if not this method 
+        returns a `.Future` (whose result after a successful 
+        connection will be the stream itself). 
+ 
+        In SSL mode, the ``server_hostname`` parameter will be used 
+        for certificate validation (unless disabled in the 
+        ``ssl_options``) and SNI (if supported; requires Python 
+        2.7.9+). 
+ 
+        Note that it is safe to call `IOStream.write 
+        <BaseIOStream.write>` while the connection is pending, in 
+        which case the data will be written as soon as the connection 
+        is ready.  Calling `IOStream` read methods before the socket is 
+        connected works on some platforms but is non-portable. 
+ 
+        .. versionchanged:: 4.0 
+            If no callback is given, returns a `.Future`. 
+ 
+        .. versionchanged:: 4.2 
+           SSL certificates are validated by default; pass 
+           ``ssl_options=dict(cert_reqs=ssl.CERT_NONE)`` or a 
+           suitably-configured `ssl.SSLContext` to the 
+           `SSLIOStream` constructor to disable. 
+        """ 
+        self._connecting = True 
+        if callback is not None: 
+            self._connect_callback = stack_context.wrap(callback) 
+            future = None 
+        else: 
+            future = self._connect_future = TracebackFuture() 
+        try: 
+            self.socket.connect(address) 
+        except socket.error as e: 
+            # In non-blocking mode we expect connect() to raise an 
+            # exception with EINPROGRESS or EWOULDBLOCK. 
+            # 
+            # On freebsd, other errors such as ECONNREFUSED may be 
+            # returned immediately when attempting to connect to 
+            # localhost, so handle them the same way as an error 
+            # reported later in _handle_connect. 
+            if (errno_from_exception(e) not in _ERRNO_INPROGRESS and 
+                    errno_from_exception(e) not in _ERRNO_WOULDBLOCK): 
+                if future is None: 
+                    gen_log.warning("Connect error on fd %s: %s", 
+                                    self.socket.fileno(), e) 
+                self.close(exc_info=True) 
+                return future 
+        self._add_io_state(self.io_loop.WRITE) 
+        return future 
+ 
+    def start_tls(self, server_side, ssl_options=None, server_hostname=None): 
+        """Convert this `IOStream` to an `SSLIOStream`. 
+ 
+        This enables protocols that begin in clear-text mode and 
+        switch to SSL after some initial negotiation (such as the 
+        ``STARTTLS`` extension to SMTP and IMAP). 
+ 
+        This method cannot be used if there are outstanding reads 
+        or writes on the stream, or if there is any data in the 
+        IOStream's buffer (data in the operating system's socket 
+        buffer is allowed).  This means it must generally be used 
+        immediately after reading or writing the last clear-text 
+        data.  It can also be used immediately after connecting, 
+        before any reads or writes. 
+ 
+        The ``ssl_options`` argument may be either an `ssl.SSLContext` 
+        object or a dictionary of keyword arguments for the 
+        `ssl.wrap_socket` function.  The ``server_hostname`` argument 
+        will be used for certificate validation unless disabled 
+        in the ``ssl_options``. 
+ 
+        This method returns a `.Future` whose result is the new 
+        `SSLIOStream`.  After this method has been called, 
+        any other operation on the original stream is undefined. 
+ 
+        If a close callback is defined on this stream, it will be 
+        transferred to the new stream. 
+ 
+        .. versionadded:: 4.0 
+ 
+        .. versionchanged:: 4.2 
+           SSL certificates are validated by default; pass 
+           ``ssl_options=dict(cert_reqs=ssl.CERT_NONE)`` or a 
+           suitably-configured `ssl.SSLContext` to disable. 
+        """ 
+        if (self._read_callback or self._read_future or 
+                self._write_callback or self._write_futures or 
+                self._connect_callback or self._connect_future or 
+                self._pending_callbacks or self._closed or 
+                self._read_buffer or self._write_buffer): 
+            raise ValueError("IOStream is not idle; cannot convert to SSL") 
+        if ssl_options is None: 
+            if server_side: 
+                ssl_options = _server_ssl_defaults 
+            else: 
+                ssl_options = _client_ssl_defaults 
+ 
+        socket = self.socket 
+        self.io_loop.remove_handler(socket) 
+        self.socket = None 
+        socket = ssl_wrap_socket(socket, ssl_options, 
+                                 server_hostname=server_hostname, 
+                                 server_side=server_side, 
+                                 do_handshake_on_connect=False) 
+        orig_close_callback = self._close_callback 
+        self._close_callback = None 
+ 
+        future = TracebackFuture() 
+        ssl_stream = SSLIOStream(socket, ssl_options=ssl_options, 
+                                 io_loop=self.io_loop) 
+        # Wrap the original close callback so we can fail our Future as well. 
+        # If we had an "unwrap" counterpart to this method we would need 
+        # to restore the original callback after our Future resolves 
+        # so that repeated wrap/unwrap calls don't build up layers. 
+ 
+        def close_callback(): 
+            if not future.done(): 
+                # Note that unlike most Futures returned by IOStream, 
+                # this one passes the underlying error through directly 
+                # instead of wrapping everything in a StreamClosedError 
+                # with a real_error attribute. This is because once the 
+                # connection is established it's more helpful to raise 
+                # the SSLError directly than to hide it behind a 
+                # StreamClosedError (and the client is expecting SSL 
+                # issues rather than network issues since this method is 
+                # named start_tls). 
+                future.set_exception(ssl_stream.error or StreamClosedError()) 
+            if orig_close_callback is not None: 
+                orig_close_callback() 
+        ssl_stream.set_close_callback(close_callback) 
+        ssl_stream._ssl_connect_callback = lambda: future.set_result(ssl_stream) 
+        ssl_stream.max_buffer_size = self.max_buffer_size 
+        ssl_stream.read_chunk_size = self.read_chunk_size 
+        return future 
+ 
+    def _handle_connect(self): 
+        err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR) 
+        if err != 0: 
+            self.error = socket.error(err, os.strerror(err)) 
+            # IOLoop implementations may vary: some of them return 
+            # an error state before the socket becomes writable, so 
+            # in that case a connection failure would be handled by the 
+            # error path in _handle_events instead of here. 
+            if self._connect_future is None: 
+                gen_log.warning("Connect error on fd %s: %s", 
+                                self.socket.fileno(), errno.errorcode[err]) 
+            self.close() 
+            return 
+        if self._connect_callback is not None: 
+            callback = self._connect_callback 
+            self._connect_callback = None 
+            self._run_callback(callback) 
+        if self._connect_future is not None: 
+            future = self._connect_future 
+            self._connect_future = None 
+            future.set_result(self) 
+        self._connecting = False 
+ 
+    def set_nodelay(self, value): 
+        if (self.socket is not None and 
+                self.socket.family in (socket.AF_INET, socket.AF_INET6)): 
+            try: 
+                self.socket.setsockopt(socket.IPPROTO_TCP, 
+                                       socket.TCP_NODELAY, 1 if value else 0) 
+            except socket.error as e: 
+                # Sometimes setsockopt will fail if the socket is closed 
+                # at the wrong time.  This can happen with HTTPServer 
+                # resetting the value to false between requests. 
+                if e.errno != errno.EINVAL and not self._is_connreset(e): 
+                    raise 
+ 
+ 
+class SSLIOStream(IOStream): 
+    """A utility class to write to and read from a non-blocking SSL socket. 
+ 
+    If the socket passed to the constructor is already connected, 
+    it should be wrapped with:: 
+ 
+        ssl.wrap_socket(sock, do_handshake_on_connect=False, **kwargs) 
+ 
+    before constructing the `SSLIOStream`.  Unconnected sockets will be 
+    wrapped when `IOStream.connect` is finished. 
+    """ 
+    def __init__(self, *args, **kwargs): 
+        """The ``ssl_options`` keyword argument may either be an 
+        `ssl.SSLContext` object or a dictionary of keywords arguments 
+        for `ssl.wrap_socket` 
+        """ 
+        self._ssl_options = kwargs.pop('ssl_options', _client_ssl_defaults) 
+        super(SSLIOStream, self).__init__(*args, **kwargs) 
+        self._ssl_accepting = True 
+        self._handshake_reading = False 
+        self._handshake_writing = False 
+        self._ssl_connect_callback = None 
+        self._server_hostname = None 
+ 
+        # If the socket is already connected, attempt to start the handshake. 
+        try: 
+            self.socket.getpeername() 
+        except socket.error: 
+            pass 
+        else: 
+            # Indirectly start the handshake, which will run on the next 
+            # IOLoop iteration and then the real IO state will be set in 
+            # _handle_events. 
+            self._add_io_state(self.io_loop.WRITE) 
+ 
+    def reading(self): 
+        return self._handshake_reading or super(SSLIOStream, self).reading() 
+ 
+    def writing(self): 
+        return self._handshake_writing or super(SSLIOStream, self).writing() 
+ 
+    def _got_empty_write(self, size): 
+        # With OpenSSL, if we couldn't write the entire buffer, 
+        # the very same string object must be used on the 
+        # next call to send.  Therefore we suppress 
+        # merging the write buffer after an incomplete send. 
+        # A cleaner solution would be to set 
+        # SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER, but this is 
+        # not yet accessible from python 
+        # (http://bugs.python.org/issue8240) 
+        self._freeze_write_buffer(size) 
+ 
+    def _do_ssl_handshake(self): 
+        # Based on code from test_ssl.py in the python stdlib 
+        try: 
+            self._handshake_reading = False 
+            self._handshake_writing = False 
+            self.socket.do_handshake() 
+        except ssl.SSLError as err: 
+            if err.args[0] == ssl.SSL_ERROR_WANT_READ: 
+                self._handshake_reading = True 
+                return 
+            elif err.args[0] == ssl.SSL_ERROR_WANT_WRITE: 
+                self._handshake_writing = True 
+                return 
+            elif err.args[0] in (ssl.SSL_ERROR_EOF, 
+                                 ssl.SSL_ERROR_ZERO_RETURN): 
+                return self.close(exc_info=True) 
+            elif err.args[0] == ssl.SSL_ERROR_SSL: 
+                try: 
+                    peer = self.socket.getpeername() 
+                except Exception: 
+                    peer = '(not connected)' 
+                gen_log.warning("SSL Error on %s %s: %s", 
+                                self.socket.fileno(), peer, err) 
+                return self.close(exc_info=True) 
+            raise 
+        except socket.error as err: 
+            # Some port scans (e.g. nmap in -sT mode) have been known 
+            # to cause do_handshake to raise EBADF and ENOTCONN, so make 
+            # those errors quiet as well. 
+            # https://groups.google.com/forum/?fromgroups#!topic/python-tornado/ApucKJat1_0 
+            if (self._is_connreset(err) or 
+                    err.args[0] in (errno.EBADF, errno.ENOTCONN)): 
+                return self.close(exc_info=True) 
+            raise 
+        except AttributeError: 
+            # On Linux, if the connection was reset before the call to 
+            # wrap_socket, do_handshake will fail with an 
+            # AttributeError. 
+            return self.close(exc_info=True) 
+        else: 
+            self._ssl_accepting = False 
+            if not self._verify_cert(self.socket.getpeercert()): 
+                self.close() 
+                return 
+            self._run_ssl_connect_callback() 
+ 
+    def _run_ssl_connect_callback(self): 
+        if self._ssl_connect_callback is not None: 
+            callback = self._ssl_connect_callback 
+            self._ssl_connect_callback = None 
+            self._run_callback(callback) 
+        if self._ssl_connect_future is not None: 
+            future = self._ssl_connect_future 
+            self._ssl_connect_future = None 
+            future.set_result(self) 
+ 
+    def _verify_cert(self, peercert): 
+        """Returns True if peercert is valid according to the configured 
+        validation mode and hostname. 
+ 
+        The ssl handshake already tested the certificate for a valid 
+        CA signature; the only thing that remains is to check 
+        the hostname. 
+        """ 
+        if isinstance(self._ssl_options, dict): 
+            verify_mode = self._ssl_options.get('cert_reqs', ssl.CERT_NONE) 
+        elif isinstance(self._ssl_options, ssl.SSLContext): 
+            verify_mode = self._ssl_options.verify_mode 
+        assert verify_mode in (ssl.CERT_NONE, ssl.CERT_REQUIRED, ssl.CERT_OPTIONAL) 
+        if verify_mode == ssl.CERT_NONE or self._server_hostname is None: 
+            return True 
+        cert = self.socket.getpeercert() 
+        if cert is None and verify_mode == ssl.CERT_REQUIRED: 
+            gen_log.warning("No SSL certificate given") 
+            return False 
+        try: 
+            ssl_match_hostname(peercert, self._server_hostname) 
+        except SSLCertificateError as e: 
+            gen_log.warning("Invalid SSL certificate: %s" % e) 
+            return False 
+        else: 
+            return True 
+ 
+    def _handle_read(self): 
+        if self._ssl_accepting: 
+            self._do_ssl_handshake() 
+            return 
+        super(SSLIOStream, self)._handle_read() 
+ 
+    def _handle_write(self): 
+        if self._ssl_accepting: 
+            self._do_ssl_handshake() 
+            return 
+        super(SSLIOStream, self)._handle_write() 
+ 
+    def connect(self, address, callback=None, server_hostname=None): 
+        self._server_hostname = server_hostname 
+        # Pass a dummy callback to super.connect(), which is slightly 
+        # more efficient than letting it return a Future we ignore. 
+        super(SSLIOStream, self).connect(address, callback=lambda: None) 
+        return self.wait_for_handshake(callback) 
+ 
+    def _handle_connect(self): 
+        # Call the superclass method to check for errors. 
+        super(SSLIOStream, self)._handle_connect() 
+        if self.closed(): 
+            return 
+        # When the connection is complete, wrap the socket for SSL 
+        # traffic.  Note that we do this by overriding _handle_connect 
+        # instead of by passing a callback to super().connect because 
+        # user callbacks are enqueued asynchronously on the IOLoop, 
+        # but since _handle_events calls _handle_connect immediately 
+        # followed by _handle_write we need this to be synchronous. 
+        # 
+        # The IOLoop will get confused if we swap out self.socket while the 
+        # fd is registered, so remove it now and re-register after 
+        # wrap_socket(). 
+        self.io_loop.remove_handler(self.socket) 
+        old_state = self._state 
+        self._state = None 
+        self.socket = ssl_wrap_socket(self.socket, self._ssl_options, 
+                                      server_hostname=self._server_hostname, 
+                                      do_handshake_on_connect=False) 
+        self._add_io_state(old_state) 
+ 
+    def wait_for_handshake(self, callback=None): 
+        """Wait for the initial SSL handshake to complete. 
+ 
+        If a ``callback`` is given, it will be called with no 
+        arguments once the handshake is complete; otherwise this 
+        method returns a `.Future` which will resolve to the 
+        stream itself after the handshake is complete. 
+ 
+        Once the handshake is complete, information such as 
+        the peer's certificate and NPN/ALPN selections may be 
+        accessed on ``self.socket``. 
+ 
+        This method is intended for use on server-side streams 
+        or after using `IOStream.start_tls`; it should not be used 
+        with `IOStream.connect` (which already waits for the 
+        handshake to complete). It may only be called once per stream. 
+ 
+        .. versionadded:: 4.2 
+        """ 
+        if (self._ssl_connect_callback is not None or 
+                self._ssl_connect_future is not None): 
+            raise RuntimeError("Already waiting") 
+        if callback is not None: 
+            self._ssl_connect_callback = stack_context.wrap(callback) 
+            future = None 
+        else: 
+            future = self._ssl_connect_future = TracebackFuture() 
+        if not self._ssl_accepting: 
+            self._run_ssl_connect_callback() 
+        return future 
+ 
+    def write_to_fd(self, data): 
+        try: 
+            return self.socket.send(data) 
+        except ssl.SSLError as e: 
+            if e.args[0] == ssl.SSL_ERROR_WANT_WRITE: 
+                # In Python 3.5+, SSLSocket.send raises a WANT_WRITE error if 
+                # the socket is not writeable; we need to transform this into 
+                # an EWOULDBLOCK socket.error or a zero return value, 
+                # either of which will be recognized by the caller of this 
+                # method. Prior to Python 3.5, an unwriteable socket would 
+                # simply return 0 bytes written. 
+                return 0 
+            raise 
+        finally: 
+            # Avoid keeping to data, which can be a memoryview. 
+            # See https://github.com/tornadoweb/tornado/pull/2008 
+            del data 
+ 
+    def read_from_fd(self): 
+        if self._ssl_accepting: 
+            # If the handshake hasn't finished yet, there can't be anything 
+            # to read (attempting to read may or may not raise an exception 
+            # depending on the SSL version) 
+            return None 
+        try: 
+            # SSLSocket objects have both a read() and recv() method, 
+            # while regular sockets only have recv(). 
+            # The recv() method blocks (at least in python 2.6) if it is 
+            # called when there is nothing to read, so we have to use 
+            # read() instead. 
+            chunk = self.socket.read(self.read_chunk_size) 
+        except ssl.SSLError as e: 
+            # SSLError is a subclass of socket.error, so this except 
+            # block must come first. 
+            if e.args[0] == ssl.SSL_ERROR_WANT_READ: 
+                return None 
+            else: 
+                raise 
+        except socket.error as e: 
+            if e.args[0] in _ERRNO_WOULDBLOCK: 
+                return None 
+            else: 
+                raise 
+        if not chunk: 
+            self.close() 
+            return None 
+        return chunk 
+ 
+    def _is_connreset(self, e): 
+        if isinstance(e, ssl.SSLError) and e.args[0] == ssl.SSL_ERROR_EOF: 
+            return True 
+        return super(SSLIOStream, self)._is_connreset(e) 
+ 
+ 
+class PipeIOStream(BaseIOStream): 
+    """Pipe-based `IOStream` implementation. 
+ 
+    The constructor takes an integer file descriptor (such as one returned 
+    by `os.pipe`) rather than an open file object.  Pipes are generally 
+    one-way, so a `PipeIOStream` can be used for reading or writing but not 
+    both. 
+    """ 
+    def __init__(self, fd, *args, **kwargs): 
+        self.fd = fd 
+        _set_nonblocking(fd) 
+        super(PipeIOStream, self).__init__(*args, **kwargs) 
+ 
+    def fileno(self): 
+        return self.fd 
+ 
+    def close_fd(self): 
+        os.close(self.fd) 
+ 
+    def write_to_fd(self, data): 
+        try: 
+            return os.write(self.fd, data) 
+        finally: 
+            # Avoid keeping to data, which can be a memoryview. 
+            # See https://github.com/tornadoweb/tornado/pull/2008 
+            del data 
+ 
+    def read_from_fd(self): 
+        try: 
+            chunk = os.read(self.fd, self.read_chunk_size) 
+        except (IOError, OSError) as e: 
+            if errno_from_exception(e) in _ERRNO_WOULDBLOCK: 
+                return None 
+            elif errno_from_exception(e) == errno.EBADF: 
+                # If the writing half of a pipe is closed, select will 
+                # report it as readable but reads will fail with EBADF. 
+                self.close(exc_info=True) 
+                return None 
+            else: 
+                raise 
+        if not chunk: 
+            self.close() 
+            return None 
+        return chunk 
+ 
+ 
+def doctests(): 
+    import doctest 
+    return doctest.DocTestSuite() 
diff --git a/contrib/python/tornado/tornado-4/tornado/locale.py b/contrib/python/tornado/tornado-4/tornado/locale.py
index 7dba10d616..682bc534b0 100644
--- a/contrib/python/tornado/tornado-4/tornado/locale.py
+++ b/contrib/python/tornado/tornado-4/tornado/locale.py
@@ -1,521 +1,521 @@
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Translation methods for generating localized strings.
-
-To load a locale and generate a translated string::
-
-    user_locale = tornado.locale.get("es_LA")
-    print(user_locale.translate("Sign out"))
-
-`tornado.locale.get()` returns the closest matching locale, not necessarily the
-specific locale you requested. You can support pluralization with
-additional arguments to `~Locale.translate()`, e.g.::
-
-    people = [...]
-    message = user_locale.translate(
-        "%(list)s is online", "%(list)s are online", len(people))
-    print(message % {"list": user_locale.list(people)})
-
-The first string is chosen if ``len(people) == 1``, otherwise the second
-string is chosen.
-
-Applications should call one of `load_translations` (which uses a simple
-CSV format) or `load_gettext_translations` (which uses the ``.mo`` format
-supported by `gettext` and related tools).  If neither method is called,
-the `Locale.translate` method will simply return the original string.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import codecs
-import csv
-import datetime
-from io import BytesIO
-import numbers
-import os
-import re
-
-from tornado import escape
-from tornado.log import gen_log
-from tornado.util import PY3
-
-from tornado._locale_data import LOCALE_NAMES
-
-_default_locale = "en_US"
-_translations = {}  # type: dict
-_supported_locales = frozenset([_default_locale])
-_use_gettext = False
-CONTEXT_SEPARATOR = "\x04"
-
-
-def get(*locale_codes):
-    """Returns the closest match for the given locale codes.
-
-    We iterate over all given locale codes in order. If we have a tight
-    or a loose match for the code (e.g., "en" for "en_US"), we return
-    the locale. Otherwise we move to the next code in the list.
-
-    By default we return ``en_US`` if no translations are found for any of
-    the specified locales. You can change the default locale with
-    `set_default_locale()`.
-    """
-    return Locale.get_closest(*locale_codes)
-
-
-def set_default_locale(code):
-    """Sets the default locale.
-
-    The default locale is assumed to be the language used for all strings
-    in the system. The translations loaded from disk are mappings from
-    the default locale to the destination locale. Consequently, you don't
-    need to create a translation file for the default locale.
-    """
-    global _default_locale
-    global _supported_locales
-    _default_locale = code
-    _supported_locales = frozenset(list(_translations.keys()) + [_default_locale])
-
-
-def load_translations(directory, encoding=None):
-    """Loads translations from CSV files in a directory.
-
-    Translations are strings with optional Python-style named placeholders
-    (e.g., ``My name is %(name)s``) and their associated translations.
-
-    The directory should have translation files of the form ``LOCALE.csv``,
-    e.g. ``es_GT.csv``. The CSV files should have two or three columns: string,
-    translation, and an optional plural indicator. Plural indicators should
-    be one of "plural" or "singular". A given string can have both singular
-    and plural forms. For example ``%(name)s liked this`` may have a
-    different verb conjugation depending on whether %(name)s is one
-    name or a list of names. There should be two rows in the CSV file for
-    that string, one with plural indicator "singular", and one "plural".
-    For strings with no verbs that would change on translation, simply
-    use "unknown" or the empty string (or don't include the column at all).
-
-    The file is read using the `csv` module in the default "excel" dialect.
-    In this format there should not be spaces after the commas.
-
-    If no ``encoding`` parameter is given, the encoding will be
-    detected automatically (among UTF-8 and UTF-16) if the file
-    contains a byte-order marker (BOM), defaulting to UTF-8 if no BOM
-    is present.
-
-    Example translation ``es_LA.csv``::
-
-        "I love you","Te amo"
-        "%(name)s liked this","A %(name)s les gustó esto","plural"
-        "%(name)s liked this","A %(name)s le gustó esto","singular"
-
-    .. versionchanged:: 4.3
-       Added ``encoding`` parameter. Added support for BOM-based encoding
-       detection, UTF-16, and UTF-8-with-BOM.
-    """
-    global _translations
-    global _supported_locales
-    _translations = {}
-    for path in os.listdir(directory):
-        if not path.endswith(".csv"):
-            continue
-        locale, extension = path.split(".")
-        if not re.match("[a-z]+(_[A-Z]+)?$", locale):
-            gen_log.error("Unrecognized locale %r (path: %s)", locale,
-                          os.path.join(directory, path))
-            continue
-        full_path = os.path.join(directory, path)
-        if encoding is None:
-            # Try to autodetect encoding based on the BOM.
-            with open(full_path, 'rb') as f:
-                data = f.read(len(codecs.BOM_UTF16_LE))
-            if data in (codecs.BOM_UTF16_LE, codecs.BOM_UTF16_BE):
-                encoding = 'utf-16'
-            else:
-                # utf-8-sig is "utf-8 with optional BOM". It's discouraged
-                # in most cases but is common with CSV files because Excel
-                # cannot read utf-8 files without a BOM.
-                encoding = 'utf-8-sig'
-        if PY3:
-            # python 3: csv.reader requires a file open in text mode.
-            # Force utf8 to avoid dependence on $LANG environment variable.
-            f = open(full_path, "r", encoding=encoding)
-        else:
-            # python 2: csv can only handle byte strings (in ascii-compatible
-            # encodings), which we decode below. Transcode everything into
-            # utf8 before passing it to csv.reader.
-            f = BytesIO()
-            with codecs.open(full_path, "r", encoding=encoding) as infile:
-                f.write(escape.utf8(infile.read()))
-            f.seek(0)
-        _translations[locale] = {}
-        for i, row in enumerate(csv.reader(f)):
-            if not row or len(row) < 2:
-                continue
-            row = [escape.to_unicode(c).strip() for c in row]
-            english, translation = row[:2]
-            if len(row) > 2:
-                plural = row[2] or "unknown"
-            else:
-                plural = "unknown"
-            if plural not in ("plural", "singular", "unknown"):
-                gen_log.error("Unrecognized plural indicator %r in %s line %d",
-                              plural, path, i + 1)
-                continue
-            _translations[locale].setdefault(plural, {})[english] = translation
-        f.close()
-    _supported_locales = frozenset(list(_translations.keys()) + [_default_locale])
-    gen_log.debug("Supported locales: %s", sorted(_supported_locales))
-
-
-def load_gettext_translations(directory, domain):
-    """Loads translations from `gettext`'s locale tree
-
-    Locale tree is similar to system's ``/usr/share/locale``, like::
-
-        {directory}/{lang}/LC_MESSAGES/{domain}.mo
-
-    Three steps are required to have your app translated:
-
-    1. Generate POT translation file::
-
-        xgettext --language=Python --keyword=_:1,2 -d mydomain file1.py file2.html etc
-
-    2. Merge against existing POT file::
-
-        msgmerge old.po mydomain.po > new.po
-
-    3. Compile::
-
-        msgfmt mydomain.po -o {directory}/pt_BR/LC_MESSAGES/mydomain.mo
-    """
-    import gettext
-    global _translations
-    global _supported_locales
-    global _use_gettext
-    _translations = {}
-    for lang in os.listdir(directory):
-        if lang.startswith('.'):
-            continue  # skip .svn, etc
-        if os.path.isfile(os.path.join(directory, lang)):
-            continue
-        try:
-            os.stat(os.path.join(directory, lang, "LC_MESSAGES", domain + ".mo"))
-            _translations[lang] = gettext.translation(domain, directory,
-                                                      languages=[lang])
-        except Exception as e:
-            gen_log.error("Cannot load translation for '%s': %s", lang, str(e))
-            continue
-    _supported_locales = frozenset(list(_translations.keys()) + [_default_locale])
-    _use_gettext = True
-    gen_log.debug("Supported locales: %s", sorted(_supported_locales))
-
-
-def get_supported_locales():
-    """Returns a list of all the supported locale codes."""
-    return _supported_locales
-
-
-class Locale(object):
-    """Object representing a locale.
-
-    After calling one of `load_translations` or `load_gettext_translations`,
-    call `get` or `get_closest` to get a Locale object.
-    """
-    @classmethod
-    def get_closest(cls, *locale_codes):
-        """Returns the closest match for the given locale code."""
-        for code in locale_codes:
-            if not code:
-                continue
-            code = code.replace("-", "_")
-            parts = code.split("_")
-            if len(parts) > 2:
-                continue
-            elif len(parts) == 2:
-                code = parts[0].lower() + "_" + parts[1].upper()
-            if code in _supported_locales:
-                return cls.get(code)
-            if parts[0].lower() in _supported_locales:
-                return cls.get(parts[0].lower())
-        return cls.get(_default_locale)
-
-    @classmethod
-    def get(cls, code):
-        """Returns the Locale for the given locale code.
-
-        If it is not supported, we raise an exception.
-        """
-        if not hasattr(cls, "_cache"):
-            cls._cache = {}
-        if code not in cls._cache:
-            assert code in _supported_locales
-            translations = _translations.get(code, None)
-            if translations is None:
-                locale = CSVLocale(code, {})
-            elif _use_gettext:
-                locale = GettextLocale(code, translations)
-            else:
-                locale = CSVLocale(code, translations)
-            cls._cache[code] = locale
-        return cls._cache[code]
-
-    def __init__(self, code, translations):
-        self.code = code
-        self.name = LOCALE_NAMES.get(code, {}).get("name", u"Unknown")
-        self.rtl = False
-        for prefix in ["fa", "ar", "he"]:
-            if self.code.startswith(prefix):
-                self.rtl = True
-                break
-        self.translations = translations
-
-        # Initialize strings for date formatting
-        _ = self.translate
-        self._months = [
-            _("January"), _("February"), _("March"), _("April"),
-            _("May"), _("June"), _("July"), _("August"),
-            _("September"), _("October"), _("November"), _("December")]
-        self._weekdays = [
-            _("Monday"), _("Tuesday"), _("Wednesday"), _("Thursday"),
-            _("Friday"), _("Saturday"), _("Sunday")]
-
-    def translate(self, message, plural_message=None, count=None):
-        """Returns the translation for the given message for this locale.
-
-        If ``plural_message`` is given, you must also provide
-        ``count``. We return ``plural_message`` when ``count != 1``,
-        and we return the singular form for the given message when
-        ``count == 1``.
-        """
-        raise NotImplementedError()
-
-    def pgettext(self, context, message, plural_message=None, count=None):
-        raise NotImplementedError()
-
-    def format_date(self, date, gmt_offset=0, relative=True, shorter=False,
-                    full_format=False):
-        """Formats the given date (which should be GMT).
-
-        By default, we return a relative time (e.g., "2 minutes ago"). You
-        can return an absolute date string with ``relative=False``.
-
-        You can force a full format date ("July 10, 1980") with
-        ``full_format=True``.
-
-        This method is primarily intended for dates in the past.
-        For dates in the future, we fall back to full format.
-        """
-        if isinstance(date, numbers.Real):
-            date = datetime.datetime.utcfromtimestamp(date)
-        now = datetime.datetime.utcnow()
-        if date > now:
-            if relative and (date - now).seconds < 60:
-                # Due to click skew, things are some things slightly
-                # in the future. Round timestamps in the immediate
-                # future down to now in relative mode.
-                date = now
-            else:
-                # Otherwise, future dates always use the full format.
-                full_format = True
-        local_date = date - datetime.timedelta(minutes=gmt_offset)
-        local_now = now - datetime.timedelta(minutes=gmt_offset)
-        local_yesterday = local_now - datetime.timedelta(hours=24)
-        difference = now - date
-        seconds = difference.seconds
-        days = difference.days
-
-        _ = self.translate
-        format = None
-        if not full_format:
-            if relative and days == 0:
-                if seconds < 50:
-                    return _("1 second ago", "%(seconds)d seconds ago",
-                             seconds) % {"seconds": seconds}
-
-                if seconds < 50 * 60:
-                    minutes = round(seconds / 60.0)
-                    return _("1 minute ago", "%(minutes)d minutes ago",
-                             minutes) % {"minutes": minutes}
-
-                hours = round(seconds / (60.0 * 60))
-                return _("1 hour ago", "%(hours)d hours ago",
-                         hours) % {"hours": hours}
-
-            if days == 0:
-                format = _("%(time)s")
-            elif days == 1 and local_date.day == local_yesterday.day and \
-                    relative:
-                format = _("yesterday") if shorter else \
-                    _("yesterday at %(time)s")
-            elif days < 5:
-                format = _("%(weekday)s") if shorter else \
-                    _("%(weekday)s at %(time)s")
-            elif days < 334:  # 11mo, since confusing for same month last year
-                format = _("%(month_name)s %(day)s") if shorter else \
-                    _("%(month_name)s %(day)s at %(time)s")
-
-        if format is None:
-            format = _("%(month_name)s %(day)s, %(year)s") if shorter else \
-                _("%(month_name)s %(day)s, %(year)s at %(time)s")
-
-        tfhour_clock = self.code not in ("en", "en_US", "zh_CN")
-        if tfhour_clock:
-            str_time = "%d:%02d" % (local_date.hour, local_date.minute)
-        elif self.code == "zh_CN":
-            str_time = "%s%d:%02d" % (
-                (u'\u4e0a\u5348', u'\u4e0b\u5348')[local_date.hour >= 12],
-                local_date.hour % 12 or 12, local_date.minute)
-        else:
-            str_time = "%d:%02d %s" % (
-                local_date.hour % 12 or 12, local_date.minute,
-                ("am", "pm")[local_date.hour >= 12])
-
-        return format % {
-            "month_name": self._months[local_date.month - 1],
-            "weekday": self._weekdays[local_date.weekday()],
-            "day": str(local_date.day),
-            "year": str(local_date.year),
-            "time": str_time
-        }
-
-    def format_day(self, date, gmt_offset=0, dow=True):
-        """Formats the given date as a day of week.
-
-        Example: "Monday, January 22". You can remove the day of week with
-        ``dow=False``.
-        """
-        local_date = date - datetime.timedelta(minutes=gmt_offset)
-        _ = self.translate
-        if dow:
-            return _("%(weekday)s, %(month_name)s %(day)s") % {
-                "month_name": self._months[local_date.month - 1],
-                "weekday": self._weekdays[local_date.weekday()],
-                "day": str(local_date.day),
-            }
-        else:
-            return _("%(month_name)s %(day)s") % {
-                "month_name": self._months[local_date.month - 1],
-                "day": str(local_date.day),
-            }
-
-    def list(self, parts):
-        """Returns a comma-separated list for the given list of parts.
-
-        The format is, e.g., "A, B and C", "A and B" or just "A" for lists
-        of size 1.
-        """
-        _ = self.translate
-        if len(parts) == 0:
-            return ""
-        if len(parts) == 1:
-            return parts[0]
-        comma = u' \u0648 ' if self.code.startswith("fa") else u", "
-        return _("%(commas)s and %(last)s") % {
-            "commas": comma.join(parts[:-1]),
-            "last": parts[len(parts) - 1],
-        }
-
-    def friendly_number(self, value):
-        """Returns a comma-separated number for the given integer."""
-        if self.code not in ("en", "en_US"):
-            return str(value)
-        value = str(value)
-        parts = []
-        while value:
-            parts.append(value[-3:])
-            value = value[:-3]
-        return ",".join(reversed(parts))
-
-
-class CSVLocale(Locale):
-    """Locale implementation using tornado's CSV translation format."""
-    def translate(self, message, plural_message=None, count=None):
-        if plural_message is not None:
-            assert count is not None
-            if count != 1:
-                message = plural_message
-                message_dict = self.translations.get("plural", {})
-            else:
-                message_dict = self.translations.get("singular", {})
-        else:
-            message_dict = self.translations.get("unknown", {})
-        return message_dict.get(message, message)
-
-    def pgettext(self, context, message, plural_message=None, count=None):
-        if self.translations:
-            gen_log.warning('pgettext is not supported by CSVLocale')
-        return self.translate(message, plural_message, count)
-
-
-class GettextLocale(Locale):
-    """Locale implementation using the `gettext` module."""
-    def __init__(self, code, translations):
-        try:
-            # python 2
-            self.ngettext = translations.ungettext
-            self.gettext = translations.ugettext
-        except AttributeError:
-            # python 3
-            self.ngettext = translations.ngettext
-            self.gettext = translations.gettext
-        # self.gettext must exist before __init__ is called, since it
-        # calls into self.translate
-        super(GettextLocale, self).__init__(code, translations)
-
-    def translate(self, message, plural_message=None, count=None):
-        if plural_message is not None:
-            assert count is not None
-            return self.ngettext(message, plural_message, count)
-        else:
-            return self.gettext(message)
-
-    def pgettext(self, context, message, plural_message=None, count=None):
-        """Allows to set context for translation, accepts plural forms.
-
-        Usage example::
-
-            pgettext("law", "right")
-            pgettext("good", "right")
-
-        Plural message example::
-
-            pgettext("organization", "club", "clubs", len(clubs))
-            pgettext("stick", "club", "clubs", len(clubs))
-
-        To generate POT file with context, add following options to step 1
-        of `load_gettext_translations` sequence::
-
-            xgettext [basic options] --keyword=pgettext:1c,2 --keyword=pgettext:1c,2,3
-
-        .. versionadded:: 4.2
-        """
-        if plural_message is not None:
-            assert count is not None
-            msgs_with_ctxt = ("%s%s%s" % (context, CONTEXT_SEPARATOR, message),
-                              "%s%s%s" % (context, CONTEXT_SEPARATOR, plural_message),
-                              count)
-            result = self.ngettext(*msgs_with_ctxt)
-            if CONTEXT_SEPARATOR in result:
-                # Translation not found
-                result = self.ngettext(message, plural_message, count)
-            return result
-        else:
-            msg_with_ctxt = "%s%s%s" % (context, CONTEXT_SEPARATOR, message)
-            result = self.gettext(msg_with_ctxt)
-            if CONTEXT_SEPARATOR in result:
-                # Translation not found
-                result = message
-            return result
+#!/usr/bin/env python 
+# -*- coding: utf-8 -*- 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Translation methods for generating localized strings. 
+ 
+To load a locale and generate a translated string:: 
+ 
+    user_locale = tornado.locale.get("es_LA") 
+    print(user_locale.translate("Sign out")) 
+ 
+`tornado.locale.get()` returns the closest matching locale, not necessarily the 
+specific locale you requested. You can support pluralization with 
+additional arguments to `~Locale.translate()`, e.g.:: 
+ 
+    people = [...] 
+    message = user_locale.translate( 
+        "%(list)s is online", "%(list)s are online", len(people)) 
+    print(message % {"list": user_locale.list(people)}) 
+ 
+The first string is chosen if ``len(people) == 1``, otherwise the second 
+string is chosen. 
+ 
+Applications should call one of `load_translations` (which uses a simple 
+CSV format) or `load_gettext_translations` (which uses the ``.mo`` format 
+supported by `gettext` and related tools).  If neither method is called, 
+the `Locale.translate` method will simply return the original string. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import codecs 
+import csv 
+import datetime 
+from io import BytesIO 
+import numbers 
+import os 
+import re 
+ 
+from tornado import escape 
+from tornado.log import gen_log 
+from tornado.util import PY3 
+ 
+from tornado._locale_data import LOCALE_NAMES 
+ 
+_default_locale = "en_US" 
+_translations = {}  # type: dict 
+_supported_locales = frozenset([_default_locale]) 
+_use_gettext = False 
+CONTEXT_SEPARATOR = "\x04" 
+ 
+ 
+def get(*locale_codes): 
+    """Returns the closest match for the given locale codes. 
+ 
+    We iterate over all given locale codes in order. If we have a tight 
+    or a loose match for the code (e.g., "en" for "en_US"), we return 
+    the locale. Otherwise we move to the next code in the list. 
+ 
+    By default we return ``en_US`` if no translations are found for any of 
+    the specified locales. You can change the default locale with 
+    `set_default_locale()`. 
+    """ 
+    return Locale.get_closest(*locale_codes) 
+ 
+ 
+def set_default_locale(code): 
+    """Sets the default locale. 
+ 
+    The default locale is assumed to be the language used for all strings 
+    in the system. The translations loaded from disk are mappings from 
+    the default locale to the destination locale. Consequently, you don't 
+    need to create a translation file for the default locale. 
+    """ 
+    global _default_locale 
+    global _supported_locales 
+    _default_locale = code 
+    _supported_locales = frozenset(list(_translations.keys()) + [_default_locale]) 
+ 
+ 
+def load_translations(directory, encoding=None): 
+    """Loads translations from CSV files in a directory. 
+ 
+    Translations are strings with optional Python-style named placeholders 
+    (e.g., ``My name is %(name)s``) and their associated translations. 
+ 
+    The directory should have translation files of the form ``LOCALE.csv``, 
+    e.g. ``es_GT.csv``. The CSV files should have two or three columns: string, 
+    translation, and an optional plural indicator. Plural indicators should 
+    be one of "plural" or "singular". A given string can have both singular 
+    and plural forms. For example ``%(name)s liked this`` may have a 
+    different verb conjugation depending on whether %(name)s is one 
+    name or a list of names. There should be two rows in the CSV file for 
+    that string, one with plural indicator "singular", and one "plural". 
+    For strings with no verbs that would change on translation, simply 
+    use "unknown" or the empty string (or don't include the column at all). 
+ 
+    The file is read using the `csv` module in the default "excel" dialect. 
+    In this format there should not be spaces after the commas. 
+ 
+    If no ``encoding`` parameter is given, the encoding will be 
+    detected automatically (among UTF-8 and UTF-16) if the file 
+    contains a byte-order marker (BOM), defaulting to UTF-8 if no BOM 
+    is present. 
+ 
+    Example translation ``es_LA.csv``:: 
+ 
+        "I love you","Te amo" 
+        "%(name)s liked this","A %(name)s les gustó esto","plural" 
+        "%(name)s liked this","A %(name)s le gustó esto","singular" 
+ 
+    .. versionchanged:: 4.3 
+       Added ``encoding`` parameter. Added support for BOM-based encoding 
+       detection, UTF-16, and UTF-8-with-BOM. 
+    """ 
+    global _translations 
+    global _supported_locales 
+    _translations = {} 
+    for path in os.listdir(directory): 
+        if not path.endswith(".csv"): 
+            continue 
+        locale, extension = path.split(".") 
+        if not re.match("[a-z]+(_[A-Z]+)?$", locale): 
+            gen_log.error("Unrecognized locale %r (path: %s)", locale, 
+                          os.path.join(directory, path)) 
+            continue 
+        full_path = os.path.join(directory, path) 
+        if encoding is None: 
+            # Try to autodetect encoding based on the BOM. 
+            with open(full_path, 'rb') as f: 
+                data = f.read(len(codecs.BOM_UTF16_LE)) 
+            if data in (codecs.BOM_UTF16_LE, codecs.BOM_UTF16_BE): 
+                encoding = 'utf-16' 
+            else: 
+                # utf-8-sig is "utf-8 with optional BOM". It's discouraged 
+                # in most cases but is common with CSV files because Excel 
+                # cannot read utf-8 files without a BOM. 
+                encoding = 'utf-8-sig' 
+        if PY3: 
+            # python 3: csv.reader requires a file open in text mode. 
+            # Force utf8 to avoid dependence on $LANG environment variable. 
+            f = open(full_path, "r", encoding=encoding) 
+        else: 
+            # python 2: csv can only handle byte strings (in ascii-compatible 
+            # encodings), which we decode below. Transcode everything into 
+            # utf8 before passing it to csv.reader. 
+            f = BytesIO() 
+            with codecs.open(full_path, "r", encoding=encoding) as infile: 
+                f.write(escape.utf8(infile.read())) 
+            f.seek(0) 
+        _translations[locale] = {} 
+        for i, row in enumerate(csv.reader(f)): 
+            if not row or len(row) < 2: 
+                continue 
+            row = [escape.to_unicode(c).strip() for c in row] 
+            english, translation = row[:2] 
+            if len(row) > 2: 
+                plural = row[2] or "unknown" 
+            else: 
+                plural = "unknown" 
+            if plural not in ("plural", "singular", "unknown"): 
+                gen_log.error("Unrecognized plural indicator %r in %s line %d", 
+                              plural, path, i + 1) 
+                continue 
+            _translations[locale].setdefault(plural, {})[english] = translation 
+        f.close() 
+    _supported_locales = frozenset(list(_translations.keys()) + [_default_locale]) 
+    gen_log.debug("Supported locales: %s", sorted(_supported_locales)) 
+ 
+ 
+def load_gettext_translations(directory, domain): 
+    """Loads translations from `gettext`'s locale tree 
+ 
+    Locale tree is similar to system's ``/usr/share/locale``, like:: 
+ 
+        {directory}/{lang}/LC_MESSAGES/{domain}.mo 
+ 
+    Three steps are required to have your app translated: 
+ 
+    1. Generate POT translation file:: 
+ 
+        xgettext --language=Python --keyword=_:1,2 -d mydomain file1.py file2.html etc 
+ 
+    2. Merge against existing POT file:: 
+ 
+        msgmerge old.po mydomain.po > new.po 
+ 
+    3. Compile:: 
+ 
+        msgfmt mydomain.po -o {directory}/pt_BR/LC_MESSAGES/mydomain.mo 
+    """ 
+    import gettext 
+    global _translations 
+    global _supported_locales 
+    global _use_gettext 
+    _translations = {} 
+    for lang in os.listdir(directory): 
+        if lang.startswith('.'): 
+            continue  # skip .svn, etc 
+        if os.path.isfile(os.path.join(directory, lang)): 
+            continue 
+        try: 
+            os.stat(os.path.join(directory, lang, "LC_MESSAGES", domain + ".mo")) 
+            _translations[lang] = gettext.translation(domain, directory, 
+                                                      languages=[lang]) 
+        except Exception as e: 
+            gen_log.error("Cannot load translation for '%s': %s", lang, str(e)) 
+            continue 
+    _supported_locales = frozenset(list(_translations.keys()) + [_default_locale]) 
+    _use_gettext = True 
+    gen_log.debug("Supported locales: %s", sorted(_supported_locales)) 
+ 
+ 
+def get_supported_locales(): 
+    """Returns a list of all the supported locale codes.""" 
+    return _supported_locales 
+ 
+ 
+class Locale(object): 
+    """Object representing a locale. 
+ 
+    After calling one of `load_translations` or `load_gettext_translations`, 
+    call `get` or `get_closest` to get a Locale object. 
+    """ 
+    @classmethod 
+    def get_closest(cls, *locale_codes): 
+        """Returns the closest match for the given locale code.""" 
+        for code in locale_codes: 
+            if not code: 
+                continue 
+            code = code.replace("-", "_") 
+            parts = code.split("_") 
+            if len(parts) > 2: 
+                continue 
+            elif len(parts) == 2: 
+                code = parts[0].lower() + "_" + parts[1].upper() 
+            if code in _supported_locales: 
+                return cls.get(code) 
+            if parts[0].lower() in _supported_locales: 
+                return cls.get(parts[0].lower()) 
+        return cls.get(_default_locale) 
+ 
+    @classmethod 
+    def get(cls, code): 
+        """Returns the Locale for the given locale code. 
+ 
+        If it is not supported, we raise an exception. 
+        """ 
+        if not hasattr(cls, "_cache"): 
+            cls._cache = {} 
+        if code not in cls._cache: 
+            assert code in _supported_locales 
+            translations = _translations.get(code, None) 
+            if translations is None: 
+                locale = CSVLocale(code, {}) 
+            elif _use_gettext: 
+                locale = GettextLocale(code, translations) 
+            else: 
+                locale = CSVLocale(code, translations) 
+            cls._cache[code] = locale 
+        return cls._cache[code] 
+ 
+    def __init__(self, code, translations): 
+        self.code = code 
+        self.name = LOCALE_NAMES.get(code, {}).get("name", u"Unknown") 
+        self.rtl = False 
+        for prefix in ["fa", "ar", "he"]: 
+            if self.code.startswith(prefix): 
+                self.rtl = True 
+                break 
+        self.translations = translations 
+ 
+        # Initialize strings for date formatting 
+        _ = self.translate 
+        self._months = [ 
+            _("January"), _("February"), _("March"), _("April"), 
+            _("May"), _("June"), _("July"), _("August"), 
+            _("September"), _("October"), _("November"), _("December")] 
+        self._weekdays = [ 
+            _("Monday"), _("Tuesday"), _("Wednesday"), _("Thursday"), 
+            _("Friday"), _("Saturday"), _("Sunday")] 
+ 
+    def translate(self, message, plural_message=None, count=None): 
+        """Returns the translation for the given message for this locale. 
+ 
+        If ``plural_message`` is given, you must also provide 
+        ``count``. We return ``plural_message`` when ``count != 1``, 
+        and we return the singular form for the given message when 
+        ``count == 1``. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def pgettext(self, context, message, plural_message=None, count=None): 
+        raise NotImplementedError() 
+ 
+    def format_date(self, date, gmt_offset=0, relative=True, shorter=False, 
+                    full_format=False): 
+        """Formats the given date (which should be GMT). 
+ 
+        By default, we return a relative time (e.g., "2 minutes ago"). You 
+        can return an absolute date string with ``relative=False``. 
+ 
+        You can force a full format date ("July 10, 1980") with 
+        ``full_format=True``. 
+ 
+        This method is primarily intended for dates in the past. 
+        For dates in the future, we fall back to full format. 
+        """ 
+        if isinstance(date, numbers.Real): 
+            date = datetime.datetime.utcfromtimestamp(date) 
+        now = datetime.datetime.utcnow() 
+        if date > now: 
+            if relative and (date - now).seconds < 60: 
+                # Due to click skew, things are some things slightly 
+                # in the future. Round timestamps in the immediate 
+                # future down to now in relative mode. 
+                date = now 
+            else: 
+                # Otherwise, future dates always use the full format. 
+                full_format = True 
+        local_date = date - datetime.timedelta(minutes=gmt_offset) 
+        local_now = now - datetime.timedelta(minutes=gmt_offset) 
+        local_yesterday = local_now - datetime.timedelta(hours=24) 
+        difference = now - date 
+        seconds = difference.seconds 
+        days = difference.days 
+ 
+        _ = self.translate 
+        format = None 
+        if not full_format: 
+            if relative and days == 0: 
+                if seconds < 50: 
+                    return _("1 second ago", "%(seconds)d seconds ago", 
+                             seconds) % {"seconds": seconds} 
+ 
+                if seconds < 50 * 60: 
+                    minutes = round(seconds / 60.0) 
+                    return _("1 minute ago", "%(minutes)d minutes ago", 
+                             minutes) % {"minutes": minutes} 
+ 
+                hours = round(seconds / (60.0 * 60)) 
+                return _("1 hour ago", "%(hours)d hours ago", 
+                         hours) % {"hours": hours} 
+ 
+            if days == 0: 
+                format = _("%(time)s") 
+            elif days == 1 and local_date.day == local_yesterday.day and \ 
+                    relative: 
+                format = _("yesterday") if shorter else \ 
+                    _("yesterday at %(time)s") 
+            elif days < 5: 
+                format = _("%(weekday)s") if shorter else \ 
+                    _("%(weekday)s at %(time)s") 
+            elif days < 334:  # 11mo, since confusing for same month last year 
+                format = _("%(month_name)s %(day)s") if shorter else \ 
+                    _("%(month_name)s %(day)s at %(time)s") 
+ 
+        if format is None: 
+            format = _("%(month_name)s %(day)s, %(year)s") if shorter else \ 
+                _("%(month_name)s %(day)s, %(year)s at %(time)s") 
+ 
+        tfhour_clock = self.code not in ("en", "en_US", "zh_CN") 
+        if tfhour_clock: 
+            str_time = "%d:%02d" % (local_date.hour, local_date.minute) 
+        elif self.code == "zh_CN": 
+            str_time = "%s%d:%02d" % ( 
+                (u'\u4e0a\u5348', u'\u4e0b\u5348')[local_date.hour >= 12], 
+                local_date.hour % 12 or 12, local_date.minute) 
+        else: 
+            str_time = "%d:%02d %s" % ( 
+                local_date.hour % 12 or 12, local_date.minute, 
+                ("am", "pm")[local_date.hour >= 12]) 
+ 
+        return format % { 
+            "month_name": self._months[local_date.month - 1], 
+            "weekday": self._weekdays[local_date.weekday()], 
+            "day": str(local_date.day), 
+            "year": str(local_date.year), 
+            "time": str_time 
+        } 
+ 
+    def format_day(self, date, gmt_offset=0, dow=True): 
+        """Formats the given date as a day of week. 
+ 
+        Example: "Monday, January 22". You can remove the day of week with 
+        ``dow=False``. 
+        """ 
+        local_date = date - datetime.timedelta(minutes=gmt_offset) 
+        _ = self.translate 
+        if dow: 
+            return _("%(weekday)s, %(month_name)s %(day)s") % { 
+                "month_name": self._months[local_date.month - 1], 
+                "weekday": self._weekdays[local_date.weekday()], 
+                "day": str(local_date.day), 
+            } 
+        else: 
+            return _("%(month_name)s %(day)s") % { 
+                "month_name": self._months[local_date.month - 1], 
+                "day": str(local_date.day), 
+            } 
+ 
+    def list(self, parts): 
+        """Returns a comma-separated list for the given list of parts. 
+ 
+        The format is, e.g., "A, B and C", "A and B" or just "A" for lists 
+        of size 1. 
+        """ 
+        _ = self.translate 
+        if len(parts) == 0: 
+            return "" 
+        if len(parts) == 1: 
+            return parts[0] 
+        comma = u' \u0648 ' if self.code.startswith("fa") else u", " 
+        return _("%(commas)s and %(last)s") % { 
+            "commas": comma.join(parts[:-1]), 
+            "last": parts[len(parts) - 1], 
+        } 
+ 
+    def friendly_number(self, value): 
+        """Returns a comma-separated number for the given integer.""" 
+        if self.code not in ("en", "en_US"): 
+            return str(value) 
+        value = str(value) 
+        parts = [] 
+        while value: 
+            parts.append(value[-3:]) 
+            value = value[:-3] 
+        return ",".join(reversed(parts)) 
+ 
+ 
+class CSVLocale(Locale): 
+    """Locale implementation using tornado's CSV translation format.""" 
+    def translate(self, message, plural_message=None, count=None): 
+        if plural_message is not None: 
+            assert count is not None 
+            if count != 1: 
+                message = plural_message 
+                message_dict = self.translations.get("plural", {}) 
+            else: 
+                message_dict = self.translations.get("singular", {}) 
+        else: 
+            message_dict = self.translations.get("unknown", {}) 
+        return message_dict.get(message, message) 
+ 
+    def pgettext(self, context, message, plural_message=None, count=None): 
+        if self.translations: 
+            gen_log.warning('pgettext is not supported by CSVLocale') 
+        return self.translate(message, plural_message, count) 
+ 
+ 
+class GettextLocale(Locale): 
+    """Locale implementation using the `gettext` module.""" 
+    def __init__(self, code, translations): 
+        try: 
+            # python 2 
+            self.ngettext = translations.ungettext 
+            self.gettext = translations.ugettext 
+        except AttributeError: 
+            # python 3 
+            self.ngettext = translations.ngettext 
+            self.gettext = translations.gettext 
+        # self.gettext must exist before __init__ is called, since it 
+        # calls into self.translate 
+        super(GettextLocale, self).__init__(code, translations) 
+ 
+    def translate(self, message, plural_message=None, count=None): 
+        if plural_message is not None: 
+            assert count is not None 
+            return self.ngettext(message, plural_message, count) 
+        else: 
+            return self.gettext(message) 
+ 
+    def pgettext(self, context, message, plural_message=None, count=None): 
+        """Allows to set context for translation, accepts plural forms. 
+ 
+        Usage example:: 
+ 
+            pgettext("law", "right") 
+            pgettext("good", "right") 
+ 
+        Plural message example:: 
+ 
+            pgettext("organization", "club", "clubs", len(clubs)) 
+            pgettext("stick", "club", "clubs", len(clubs)) 
+ 
+        To generate POT file with context, add following options to step 1 
+        of `load_gettext_translations` sequence:: 
+ 
+            xgettext [basic options] --keyword=pgettext:1c,2 --keyword=pgettext:1c,2,3 
+ 
+        .. versionadded:: 4.2 
+        """ 
+        if plural_message is not None: 
+            assert count is not None 
+            msgs_with_ctxt = ("%s%s%s" % (context, CONTEXT_SEPARATOR, message), 
+                              "%s%s%s" % (context, CONTEXT_SEPARATOR, plural_message), 
+                              count) 
+            result = self.ngettext(*msgs_with_ctxt) 
+            if CONTEXT_SEPARATOR in result: 
+                # Translation not found 
+                result = self.ngettext(message, plural_message, count) 
+            return result 
+        else: 
+            msg_with_ctxt = "%s%s%s" % (context, CONTEXT_SEPARATOR, message) 
+            result = self.gettext(msg_with_ctxt) 
+            if CONTEXT_SEPARATOR in result: 
+                # Translation not found 
+                result = message 
+            return result 
diff --git a/contrib/python/tornado/tornado-4/tornado/locks.py b/contrib/python/tornado/tornado-4/tornado/locks.py
index 4f9ecf6dfd..6099c9f95a 100644
--- a/contrib/python/tornado/tornado-4/tornado/locks.py
+++ b/contrib/python/tornado/tornado-4/tornado/locks.py
@@ -1,512 +1,512 @@
-# Copyright 2015 The Tornado Authors
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-from __future__ import absolute_import, division, print_function
-
-import collections
-
-from tornado import gen, ioloop
-from tornado.concurrent import Future
-
-__all__ = ['Condition', 'Event', 'Semaphore', 'BoundedSemaphore', 'Lock']
-
-
-class _TimeoutGarbageCollector(object):
-    """Base class for objects that periodically clean up timed-out waiters.
-
-    Avoids memory leak in a common pattern like:
-
-        while True:
-            yield condition.wait(short_timeout)
-            print('looping....')
-    """
-    def __init__(self):
-        self._waiters = collections.deque()  # Futures.
-        self._timeouts = 0
-
-    def _garbage_collect(self):
-        # Occasionally clear timed-out waiters.
-        self._timeouts += 1
-        if self._timeouts > 100:
-            self._timeouts = 0
-            self._waiters = collections.deque(
-                w for w in self._waiters if not w.done())
-
-
-class Condition(_TimeoutGarbageCollector):
-    """A condition allows one or more coroutines to wait until notified.
-
-    Like a standard `threading.Condition`, but does not need an underlying lock
-    that is acquired and released.
-
-    With a `Condition`, coroutines can wait to be notified by other coroutines:
-
-    .. testcode::
-
-        from tornado import gen
-        from tornado.ioloop import IOLoop
-        from tornado.locks import Condition
-
-        condition = Condition()
-
-        @gen.coroutine
-        def waiter():
-            print("I'll wait right here")
-            yield condition.wait()  # Yield a Future.
-            print("I'm done waiting")
-
-        @gen.coroutine
-        def notifier():
-            print("About to notify")
-            condition.notify()
-            print("Done notifying")
-
-        @gen.coroutine
-        def runner():
-            # Yield two Futures; wait for waiter() and notifier() to finish.
-            yield [waiter(), notifier()]
-
-        IOLoop.current().run_sync(runner)
-
-    .. testoutput::
-
-        I'll wait right here
-        About to notify
-        Done notifying
-        I'm done waiting
-
-    `wait` takes an optional ``timeout`` argument, which is either an absolute
-    timestamp::
-
-        io_loop = IOLoop.current()
-
-        # Wait up to 1 second for a notification.
-        yield condition.wait(timeout=io_loop.time() + 1)
-
-    ...or a `datetime.timedelta` for a timeout relative to the current time::
-
-        # Wait up to 1 second.
-        yield condition.wait(timeout=datetime.timedelta(seconds=1))
-
-    The method raises `tornado.gen.TimeoutError` if there's no notification
-    before the deadline.
-    """
-
-    def __init__(self):
-        super(Condition, self).__init__()
-        self.io_loop = ioloop.IOLoop.current()
-
-    def __repr__(self):
-        result = '<%s' % (self.__class__.__name__, )
-        if self._waiters:
-            result += ' waiters[%s]' % len(self._waiters)
-        return result + '>'
-
-    def wait(self, timeout=None):
-        """Wait for `.notify`.
-
-        Returns a `.Future` that resolves ``True`` if the condition is notified,
-        or ``False`` after a timeout.
-        """
-        waiter = Future()
-        self._waiters.append(waiter)
-        if timeout:
-            def on_timeout():
-                waiter.set_result(False)
-                self._garbage_collect()
-            io_loop = ioloop.IOLoop.current()
-            timeout_handle = io_loop.add_timeout(timeout, on_timeout)
-            waiter.add_done_callback(
-                lambda _: io_loop.remove_timeout(timeout_handle))
-        return waiter
-
-    def notify(self, n=1):
-        """Wake ``n`` waiters."""
-        waiters = []  # Waiters we plan to run right now.
-        while n and self._waiters:
-            waiter = self._waiters.popleft()
-            if not waiter.done():  # Might have timed out.
-                n -= 1
-                waiters.append(waiter)
-
-        for waiter in waiters:
-            waiter.set_result(True)
-
-    def notify_all(self):
-        """Wake all waiters."""
-        self.notify(len(self._waiters))
-
-
-class Event(object):
-    """An event blocks coroutines until its internal flag is set to True.
-
-    Similar to `threading.Event`.
-
-    A coroutine can wait for an event to be set. Once it is set, calls to
-    ``yield event.wait()`` will not block unless the event has been cleared:
-
-    .. testcode::
-
-        from tornado import gen
-        from tornado.ioloop import IOLoop
-        from tornado.locks import Event
-
-        event = Event()
-
-        @gen.coroutine
-        def waiter():
-            print("Waiting for event")
-            yield event.wait()
-            print("Not waiting this time")
-            yield event.wait()
-            print("Done")
-
-        @gen.coroutine
-        def setter():
-            print("About to set the event")
-            event.set()
-
-        @gen.coroutine
-        def runner():
-            yield [waiter(), setter()]
-
-        IOLoop.current().run_sync(runner)
-
-    .. testoutput::
-
-        Waiting for event
-        About to set the event
-        Not waiting this time
-        Done
-    """
-    def __init__(self):
-        self._future = Future()
-
-    def __repr__(self):
-        return '<%s %s>' % (
-            self.__class__.__name__, 'set' if self.is_set() else 'clear')
-
-    def is_set(self):
-        """Return ``True`` if the internal flag is true."""
-        return self._future.done()
-
-    def set(self):
-        """Set the internal flag to ``True``. All waiters are awakened.
-
-        Calling `.wait` once the flag is set will not block.
-        """
-        if not self._future.done():
-            self._future.set_result(None)
-
-    def clear(self):
-        """Reset the internal flag to ``False``.
-
-        Calls to `.wait` will block until `.set` is called.
-        """
-        if self._future.done():
-            self._future = Future()
-
-    def wait(self, timeout=None):
-        """Block until the internal flag is true.
-
-        Returns a Future, which raises `tornado.gen.TimeoutError` after a
-        timeout.
-        """
-        if timeout is None:
-            return self._future
-        else:
-            return gen.with_timeout(timeout, self._future)
-
-
-class _ReleasingContextManager(object):
-    """Releases a Lock or Semaphore at the end of a "with" statement.
-
-        with (yield semaphore.acquire()):
-            pass
-
-        # Now semaphore.release() has been called.
-    """
-    def __init__(self, obj):
-        self._obj = obj
-
-    def __enter__(self):
-        pass
-
-    def __exit__(self, exc_type, exc_val, exc_tb):
-        self._obj.release()
-
-
-class Semaphore(_TimeoutGarbageCollector):
-    """A lock that can be acquired a fixed number of times before blocking.
-
-    A Semaphore manages a counter representing the number of `.release` calls
-    minus the number of `.acquire` calls, plus an initial value. The `.acquire`
-    method blocks if necessary until it can return without making the counter
-    negative.
-
-    Semaphores limit access to a shared resource. To allow access for two
-    workers at a time:
-
-    .. testsetup:: semaphore
-
-       from collections import deque
-
-       from tornado import gen
-       from tornado.ioloop import IOLoop
-       from tornado.concurrent import Future
-
-       # Ensure reliable doctest output: resolve Futures one at a time.
-       futures_q = deque([Future() for _ in range(3)])
-
-       @gen.coroutine
-       def simulator(futures):
-           for f in futures:
-               yield gen.moment
-               f.set_result(None)
-
-       IOLoop.current().add_callback(simulator, list(futures_q))
-
-       def use_some_resource():
-           return futures_q.popleft()
-
-    .. testcode:: semaphore
-
-        from tornado import gen
-        from tornado.ioloop import IOLoop
-        from tornado.locks import Semaphore
-
-        sem = Semaphore(2)
-
-        @gen.coroutine
-        def worker(worker_id):
-            yield sem.acquire()
-            try:
-                print("Worker %d is working" % worker_id)
-                yield use_some_resource()
-            finally:
-                print("Worker %d is done" % worker_id)
-                sem.release()
-
-        @gen.coroutine
-        def runner():
-            # Join all workers.
-            yield [worker(i) for i in range(3)]
-
-        IOLoop.current().run_sync(runner)
-
-    .. testoutput:: semaphore
-
-        Worker 0 is working
-        Worker 1 is working
-        Worker 0 is done
-        Worker 2 is working
-        Worker 1 is done
-        Worker 2 is done
-
-    Workers 0 and 1 are allowed to run concurrently, but worker 2 waits until
-    the semaphore has been released once, by worker 0.
-
-    `.acquire` is a context manager, so ``worker`` could be written as::
-
-        @gen.coroutine
-        def worker(worker_id):
-            with (yield sem.acquire()):
-                print("Worker %d is working" % worker_id)
-                yield use_some_resource()
-
-            # Now the semaphore has been released.
-            print("Worker %d is done" % worker_id)
-
-    In Python 3.5, the semaphore itself can be used as an async context
-    manager::
-
-        async def worker(worker_id):
-            async with sem:
-                print("Worker %d is working" % worker_id)
-                await use_some_resource()
-
-            # Now the semaphore has been released.
-            print("Worker %d is done" % worker_id)
-
-    .. versionchanged:: 4.3
-       Added ``async with`` support in Python 3.5.
-    """
-    def __init__(self, value=1):
-        super(Semaphore, self).__init__()
-        if value < 0:
-            raise ValueError('semaphore initial value must be >= 0')
-
-        self._value = value
-
-    def __repr__(self):
-        res = super(Semaphore, self).__repr__()
-        extra = 'locked' if self._value == 0 else 'unlocked,value:{0}'.format(
-            self._value)
-        if self._waiters:
-            extra = '{0},waiters:{1}'.format(extra, len(self._waiters))
-        return '<{0} [{1}]>'.format(res[1:-1], extra)
-
-    def release(self):
-        """Increment the counter and wake one waiter."""
-        self._value += 1
-        while self._waiters:
-            waiter = self._waiters.popleft()
-            if not waiter.done():
-                self._value -= 1
-
-                # If the waiter is a coroutine paused at
-                #
-                #     with (yield semaphore.acquire()):
-                #
-                # then the context manager's __exit__ calls release() at the end
-                # of the "with" block.
-                waiter.set_result(_ReleasingContextManager(self))
-                break
-
-    def acquire(self, timeout=None):
-        """Decrement the counter. Returns a Future.
-
-        Block if the counter is zero and wait for a `.release`. The Future
-        raises `.TimeoutError` after the deadline.
-        """
-        waiter = Future()
-        if self._value > 0:
-            self._value -= 1
-            waiter.set_result(_ReleasingContextManager(self))
-        else:
-            self._waiters.append(waiter)
-            if timeout:
-                def on_timeout():
-                    waiter.set_exception(gen.TimeoutError())
-                    self._garbage_collect()
-                io_loop = ioloop.IOLoop.current()
-                timeout_handle = io_loop.add_timeout(timeout, on_timeout)
-                waiter.add_done_callback(
-                    lambda _: io_loop.remove_timeout(timeout_handle))
-        return waiter
-
-    def __enter__(self):
-        raise RuntimeError(
-            "Use Semaphore like 'with (yield semaphore.acquire())', not like"
-            " 'with semaphore'")
-
-    __exit__ = __enter__
-
-    @gen.coroutine
-    def __aenter__(self):
-        yield self.acquire()
-
-    @gen.coroutine
-    def __aexit__(self, typ, value, tb):
-        self.release()
-
-
-class BoundedSemaphore(Semaphore):
-    """A semaphore that prevents release() being called too many times.
-
-    If `.release` would increment the semaphore's value past the initial
-    value, it raises `ValueError`. Semaphores are mostly used to guard
-    resources with limited capacity, so a semaphore released too many times
-    is a sign of a bug.
-    """
-    def __init__(self, value=1):
-        super(BoundedSemaphore, self).__init__(value=value)
-        self._initial_value = value
-
-    def release(self):
-        """Increment the counter and wake one waiter."""
-        if self._value >= self._initial_value:
-            raise ValueError("Semaphore released too many times")
-        super(BoundedSemaphore, self).release()
-
-
-class Lock(object):
-    """A lock for coroutines.
-
-    A Lock begins unlocked, and `acquire` locks it immediately. While it is
-    locked, a coroutine that yields `acquire` waits until another coroutine
-    calls `release`.
-
-    Releasing an unlocked lock raises `RuntimeError`.
-
-    `acquire` supports the context manager protocol in all Python versions:
-
-    >>> from tornado import gen, locks
-    >>> lock = locks.Lock()
-    >>>
-    >>> @gen.coroutine
-    ... def f():
-    ...    with (yield lock.acquire()):
-    ...        # Do something holding the lock.
-    ...        pass
-    ...
-    ...    # Now the lock is released.
-
-    In Python 3.5, `Lock` also supports the async context manager
-    protocol. Note that in this case there is no `acquire`, because
-    ``async with`` includes both the ``yield`` and the ``acquire``
-    (just as it does with `threading.Lock`):
-
-    >>> async def f():  # doctest: +SKIP
-    ...    async with lock:
-    ...        # Do something holding the lock.
-    ...        pass
-    ...
-    ...    # Now the lock is released.
-
-    .. versionchanged:: 4.3
-       Added ``async with`` support in Python 3.5.
-
-    """
-    def __init__(self):
-        self._block = BoundedSemaphore(value=1)
-
-    def __repr__(self):
-        return "<%s _block=%s>" % (
-            self.__class__.__name__,
-            self._block)
-
-    def acquire(self, timeout=None):
-        """Attempt to lock. Returns a Future.
-
-        Returns a Future, which raises `tornado.gen.TimeoutError` after a
-        timeout.
-        """
-        return self._block.acquire(timeout)
-
-    def release(self):
-        """Unlock.
-
-        The first coroutine in line waiting for `acquire` gets the lock.
-
-        If not locked, raise a `RuntimeError`.
-        """
-        try:
-            self._block.release()
-        except ValueError:
-            raise RuntimeError('release unlocked lock')
-
-    def __enter__(self):
-        raise RuntimeError(
-            "Use Lock like 'with (yield lock)', not like 'with lock'")
-
-    __exit__ = __enter__
-
-    @gen.coroutine
-    def __aenter__(self):
-        yield self.acquire()
-
-    @gen.coroutine
-    def __aexit__(self, typ, value, tb):
-        self.release()
+# Copyright 2015 The Tornado Authors 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import collections 
+ 
+from tornado import gen, ioloop 
+from tornado.concurrent import Future 
+ 
+__all__ = ['Condition', 'Event', 'Semaphore', 'BoundedSemaphore', 'Lock'] 
+ 
+ 
+class _TimeoutGarbageCollector(object): 
+    """Base class for objects that periodically clean up timed-out waiters. 
+ 
+    Avoids memory leak in a common pattern like: 
+ 
+        while True: 
+            yield condition.wait(short_timeout) 
+            print('looping....') 
+    """ 
+    def __init__(self): 
+        self._waiters = collections.deque()  # Futures. 
+        self._timeouts = 0 
+ 
+    def _garbage_collect(self): 
+        # Occasionally clear timed-out waiters. 
+        self._timeouts += 1 
+        if self._timeouts > 100: 
+            self._timeouts = 0 
+            self._waiters = collections.deque( 
+                w for w in self._waiters if not w.done()) 
+ 
+ 
+class Condition(_TimeoutGarbageCollector): 
+    """A condition allows one or more coroutines to wait until notified. 
+ 
+    Like a standard `threading.Condition`, but does not need an underlying lock 
+    that is acquired and released. 
+ 
+    With a `Condition`, coroutines can wait to be notified by other coroutines: 
+ 
+    .. testcode:: 
+ 
+        from tornado import gen 
+        from tornado.ioloop import IOLoop 
+        from tornado.locks import Condition 
+ 
+        condition = Condition() 
+ 
+        @gen.coroutine 
+        def waiter(): 
+            print("I'll wait right here") 
+            yield condition.wait()  # Yield a Future. 
+            print("I'm done waiting") 
+ 
+        @gen.coroutine 
+        def notifier(): 
+            print("About to notify") 
+            condition.notify() 
+            print("Done notifying") 
+ 
+        @gen.coroutine 
+        def runner(): 
+            # Yield two Futures; wait for waiter() and notifier() to finish. 
+            yield [waiter(), notifier()] 
+ 
+        IOLoop.current().run_sync(runner) 
+ 
+    .. testoutput:: 
+ 
+        I'll wait right here 
+        About to notify 
+        Done notifying 
+        I'm done waiting 
+ 
+    `wait` takes an optional ``timeout`` argument, which is either an absolute 
+    timestamp:: 
+ 
+        io_loop = IOLoop.current() 
+ 
+        # Wait up to 1 second for a notification. 
+        yield condition.wait(timeout=io_loop.time() + 1) 
+ 
+    ...or a `datetime.timedelta` for a timeout relative to the current time:: 
+ 
+        # Wait up to 1 second. 
+        yield condition.wait(timeout=datetime.timedelta(seconds=1)) 
+ 
+    The method raises `tornado.gen.TimeoutError` if there's no notification 
+    before the deadline. 
+    """ 
+ 
+    def __init__(self): 
+        super(Condition, self).__init__() 
+        self.io_loop = ioloop.IOLoop.current() 
+ 
+    def __repr__(self): 
+        result = '<%s' % (self.__class__.__name__, ) 
+        if self._waiters: 
+            result += ' waiters[%s]' % len(self._waiters) 
+        return result + '>' 
+ 
+    def wait(self, timeout=None): 
+        """Wait for `.notify`. 
+ 
+        Returns a `.Future` that resolves ``True`` if the condition is notified, 
+        or ``False`` after a timeout. 
+        """ 
+        waiter = Future() 
+        self._waiters.append(waiter) 
+        if timeout: 
+            def on_timeout(): 
+                waiter.set_result(False) 
+                self._garbage_collect() 
+            io_loop = ioloop.IOLoop.current() 
+            timeout_handle = io_loop.add_timeout(timeout, on_timeout) 
+            waiter.add_done_callback( 
+                lambda _: io_loop.remove_timeout(timeout_handle)) 
+        return waiter 
+ 
+    def notify(self, n=1): 
+        """Wake ``n`` waiters.""" 
+        waiters = []  # Waiters we plan to run right now. 
+        while n and self._waiters: 
+            waiter = self._waiters.popleft() 
+            if not waiter.done():  # Might have timed out. 
+                n -= 1 
+                waiters.append(waiter) 
+ 
+        for waiter in waiters: 
+            waiter.set_result(True) 
+ 
+    def notify_all(self): 
+        """Wake all waiters.""" 
+        self.notify(len(self._waiters)) 
+ 
+ 
+class Event(object): 
+    """An event blocks coroutines until its internal flag is set to True. 
+ 
+    Similar to `threading.Event`. 
+ 
+    A coroutine can wait for an event to be set. Once it is set, calls to 
+    ``yield event.wait()`` will not block unless the event has been cleared: 
+ 
+    .. testcode:: 
+ 
+        from tornado import gen 
+        from tornado.ioloop import IOLoop 
+        from tornado.locks import Event 
+ 
+        event = Event() 
+ 
+        @gen.coroutine 
+        def waiter(): 
+            print("Waiting for event") 
+            yield event.wait() 
+            print("Not waiting this time") 
+            yield event.wait() 
+            print("Done") 
+ 
+        @gen.coroutine 
+        def setter(): 
+            print("About to set the event") 
+            event.set() 
+ 
+        @gen.coroutine 
+        def runner(): 
+            yield [waiter(), setter()] 
+ 
+        IOLoop.current().run_sync(runner) 
+ 
+    .. testoutput:: 
+ 
+        Waiting for event 
+        About to set the event 
+        Not waiting this time 
+        Done 
+    """ 
+    def __init__(self): 
+        self._future = Future() 
+ 
+    def __repr__(self): 
+        return '<%s %s>' % ( 
+            self.__class__.__name__, 'set' if self.is_set() else 'clear') 
+ 
+    def is_set(self): 
+        """Return ``True`` if the internal flag is true.""" 
+        return self._future.done() 
+ 
+    def set(self): 
+        """Set the internal flag to ``True``. All waiters are awakened. 
+ 
+        Calling `.wait` once the flag is set will not block. 
+        """ 
+        if not self._future.done(): 
+            self._future.set_result(None) 
+ 
+    def clear(self): 
+        """Reset the internal flag to ``False``. 
+ 
+        Calls to `.wait` will block until `.set` is called. 
+        """ 
+        if self._future.done(): 
+            self._future = Future() 
+ 
+    def wait(self, timeout=None): 
+        """Block until the internal flag is true. 
+ 
+        Returns a Future, which raises `tornado.gen.TimeoutError` after a 
+        timeout. 
+        """ 
+        if timeout is None: 
+            return self._future 
+        else: 
+            return gen.with_timeout(timeout, self._future) 
+ 
+ 
+class _ReleasingContextManager(object): 
+    """Releases a Lock or Semaphore at the end of a "with" statement. 
+ 
+        with (yield semaphore.acquire()): 
+            pass 
+ 
+        # Now semaphore.release() has been called. 
+    """ 
+    def __init__(self, obj): 
+        self._obj = obj 
+ 
+    def __enter__(self): 
+        pass 
+ 
+    def __exit__(self, exc_type, exc_val, exc_tb): 
+        self._obj.release() 
+ 
+ 
+class Semaphore(_TimeoutGarbageCollector): 
+    """A lock that can be acquired a fixed number of times before blocking. 
+ 
+    A Semaphore manages a counter representing the number of `.release` calls 
+    minus the number of `.acquire` calls, plus an initial value. The `.acquire` 
+    method blocks if necessary until it can return without making the counter 
+    negative. 
+ 
+    Semaphores limit access to a shared resource. To allow access for two 
+    workers at a time: 
+ 
+    .. testsetup:: semaphore 
+ 
+       from collections import deque 
+ 
+       from tornado import gen 
+       from tornado.ioloop import IOLoop 
+       from tornado.concurrent import Future 
+ 
+       # Ensure reliable doctest output: resolve Futures one at a time. 
+       futures_q = deque([Future() for _ in range(3)]) 
+ 
+       @gen.coroutine 
+       def simulator(futures): 
+           for f in futures: 
+               yield gen.moment 
+               f.set_result(None) 
+ 
+       IOLoop.current().add_callback(simulator, list(futures_q)) 
+ 
+       def use_some_resource(): 
+           return futures_q.popleft() 
+ 
+    .. testcode:: semaphore 
+ 
+        from tornado import gen 
+        from tornado.ioloop import IOLoop 
+        from tornado.locks import Semaphore 
+ 
+        sem = Semaphore(2) 
+ 
+        @gen.coroutine 
+        def worker(worker_id): 
+            yield sem.acquire() 
+            try: 
+                print("Worker %d is working" % worker_id) 
+                yield use_some_resource() 
+            finally: 
+                print("Worker %d is done" % worker_id) 
+                sem.release() 
+ 
+        @gen.coroutine 
+        def runner(): 
+            # Join all workers. 
+            yield [worker(i) for i in range(3)] 
+ 
+        IOLoop.current().run_sync(runner) 
+ 
+    .. testoutput:: semaphore 
+ 
+        Worker 0 is working 
+        Worker 1 is working 
+        Worker 0 is done 
+        Worker 2 is working 
+        Worker 1 is done 
+        Worker 2 is done 
+ 
+    Workers 0 and 1 are allowed to run concurrently, but worker 2 waits until 
+    the semaphore has been released once, by worker 0. 
+ 
+    `.acquire` is a context manager, so ``worker`` could be written as:: 
+ 
+        @gen.coroutine 
+        def worker(worker_id): 
+            with (yield sem.acquire()): 
+                print("Worker %d is working" % worker_id) 
+                yield use_some_resource() 
+ 
+            # Now the semaphore has been released. 
+            print("Worker %d is done" % worker_id) 
+ 
+    In Python 3.5, the semaphore itself can be used as an async context 
+    manager:: 
+ 
+        async def worker(worker_id): 
+            async with sem: 
+                print("Worker %d is working" % worker_id) 
+                await use_some_resource() 
+ 
+            # Now the semaphore has been released. 
+            print("Worker %d is done" % worker_id) 
+ 
+    .. versionchanged:: 4.3 
+       Added ``async with`` support in Python 3.5. 
+    """ 
+    def __init__(self, value=1): 
+        super(Semaphore, self).__init__() 
+        if value < 0: 
+            raise ValueError('semaphore initial value must be >= 0') 
+ 
+        self._value = value 
+ 
+    def __repr__(self): 
+        res = super(Semaphore, self).__repr__() 
+        extra = 'locked' if self._value == 0 else 'unlocked,value:{0}'.format( 
+            self._value) 
+        if self._waiters: 
+            extra = '{0},waiters:{1}'.format(extra, len(self._waiters)) 
+        return '<{0} [{1}]>'.format(res[1:-1], extra) 
+ 
+    def release(self): 
+        """Increment the counter and wake one waiter.""" 
+        self._value += 1 
+        while self._waiters: 
+            waiter = self._waiters.popleft() 
+            if not waiter.done(): 
+                self._value -= 1 
+ 
+                # If the waiter is a coroutine paused at 
+                # 
+                #     with (yield semaphore.acquire()): 
+                # 
+                # then the context manager's __exit__ calls release() at the end 
+                # of the "with" block. 
+                waiter.set_result(_ReleasingContextManager(self)) 
+                break 
+ 
+    def acquire(self, timeout=None): 
+        """Decrement the counter. Returns a Future. 
+ 
+        Block if the counter is zero and wait for a `.release`. The Future 
+        raises `.TimeoutError` after the deadline. 
+        """ 
+        waiter = Future() 
+        if self._value > 0: 
+            self._value -= 1 
+            waiter.set_result(_ReleasingContextManager(self)) 
+        else: 
+            self._waiters.append(waiter) 
+            if timeout: 
+                def on_timeout(): 
+                    waiter.set_exception(gen.TimeoutError()) 
+                    self._garbage_collect() 
+                io_loop = ioloop.IOLoop.current() 
+                timeout_handle = io_loop.add_timeout(timeout, on_timeout) 
+                waiter.add_done_callback( 
+                    lambda _: io_loop.remove_timeout(timeout_handle)) 
+        return waiter 
+ 
+    def __enter__(self): 
+        raise RuntimeError( 
+            "Use Semaphore like 'with (yield semaphore.acquire())', not like" 
+            " 'with semaphore'") 
+ 
+    __exit__ = __enter__ 
+ 
+    @gen.coroutine 
+    def __aenter__(self): 
+        yield self.acquire() 
+ 
+    @gen.coroutine 
+    def __aexit__(self, typ, value, tb): 
+        self.release() 
+ 
+ 
+class BoundedSemaphore(Semaphore): 
+    """A semaphore that prevents release() being called too many times. 
+ 
+    If `.release` would increment the semaphore's value past the initial 
+    value, it raises `ValueError`. Semaphores are mostly used to guard 
+    resources with limited capacity, so a semaphore released too many times 
+    is a sign of a bug. 
+    """ 
+    def __init__(self, value=1): 
+        super(BoundedSemaphore, self).__init__(value=value) 
+        self._initial_value = value 
+ 
+    def release(self): 
+        """Increment the counter and wake one waiter.""" 
+        if self._value >= self._initial_value: 
+            raise ValueError("Semaphore released too many times") 
+        super(BoundedSemaphore, self).release() 
+ 
+ 
+class Lock(object): 
+    """A lock for coroutines. 
+ 
+    A Lock begins unlocked, and `acquire` locks it immediately. While it is 
+    locked, a coroutine that yields `acquire` waits until another coroutine 
+    calls `release`. 
+ 
+    Releasing an unlocked lock raises `RuntimeError`. 
+ 
+    `acquire` supports the context manager protocol in all Python versions: 
+ 
+    >>> from tornado import gen, locks 
+    >>> lock = locks.Lock() 
+    >>> 
+    >>> @gen.coroutine 
+    ... def f(): 
+    ...    with (yield lock.acquire()): 
+    ...        # Do something holding the lock. 
+    ...        pass 
+    ... 
+    ...    # Now the lock is released. 
+ 
+    In Python 3.5, `Lock` also supports the async context manager 
+    protocol. Note that in this case there is no `acquire`, because 
+    ``async with`` includes both the ``yield`` and the ``acquire`` 
+    (just as it does with `threading.Lock`): 
+ 
+    >>> async def f():  # doctest: +SKIP 
+    ...    async with lock: 
+    ...        # Do something holding the lock. 
+    ...        pass 
+    ... 
+    ...    # Now the lock is released. 
+ 
+    .. versionchanged:: 4.3 
+       Added ``async with`` support in Python 3.5. 
+ 
+    """ 
+    def __init__(self): 
+        self._block = BoundedSemaphore(value=1) 
+ 
+    def __repr__(self): 
+        return "<%s _block=%s>" % ( 
+            self.__class__.__name__, 
+            self._block) 
+ 
+    def acquire(self, timeout=None): 
+        """Attempt to lock. Returns a Future. 
+ 
+        Returns a Future, which raises `tornado.gen.TimeoutError` after a 
+        timeout. 
+        """ 
+        return self._block.acquire(timeout) 
+ 
+    def release(self): 
+        """Unlock. 
+ 
+        The first coroutine in line waiting for `acquire` gets the lock. 
+ 
+        If not locked, raise a `RuntimeError`. 
+        """ 
+        try: 
+            self._block.release() 
+        except ValueError: 
+            raise RuntimeError('release unlocked lock') 
+ 
+    def __enter__(self): 
+        raise RuntimeError( 
+            "Use Lock like 'with (yield lock)', not like 'with lock'") 
+ 
+    __exit__ = __enter__ 
+ 
+    @gen.coroutine 
+    def __aenter__(self): 
+        yield self.acquire() 
+ 
+    @gen.coroutine 
+    def __aexit__(self, typ, value, tb): 
+        self.release() 
diff --git a/contrib/python/tornado/tornado-4/tornado/log.py b/contrib/python/tornado/tornado-4/tornado/log.py
index 654afc021e..b5ddb75e98 100644
--- a/contrib/python/tornado/tornado-4/tornado/log.py
+++ b/contrib/python/tornado/tornado-4/tornado/log.py
@@ -1,290 +1,290 @@
-#!/usr/bin/env python
-#
-# Copyright 2012 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-"""Logging support for Tornado.
-
-Tornado uses three logger streams:
-
-* ``tornado.access``: Per-request logging for Tornado's HTTP servers (and
-  potentially other servers in the future)
-* ``tornado.application``: Logging of errors from application code (i.e.
-  uncaught exceptions from callbacks)
-* ``tornado.general``: General-purpose logging, including any errors
-  or warnings from Tornado itself.
-
-These streams may be configured independently using the standard library's
-`logging` module.  For example, you may wish to send ``tornado.access`` logs
-to a separate file for analysis.
-"""
-from __future__ import absolute_import, division, print_function
-
-import logging
-import logging.handlers
-import sys
-
-from tornado.escape import _unicode
-from tornado.util import unicode_type, basestring_type
-
-try:
-    import colorama
-except ImportError:
-    colorama = None
-
-try:
-    import curses  # type: ignore
-except ImportError:
-    curses = None
-
-# Logger objects for internal tornado use
-access_log = logging.getLogger("tornado.access")
-app_log = logging.getLogger("tornado.application")
-gen_log = logging.getLogger("tornado.general")
-
-
-def _stderr_supports_color():
-    try:
-        if hasattr(sys.stderr, 'isatty') and sys.stderr.isatty():
-            if curses:
-                curses.setupterm()
-                if curses.tigetnum("colors") > 0:
-                    return True
-            elif colorama:
-                if sys.stderr is getattr(colorama.initialise, 'wrapped_stderr',
-                                         object()):
-                    return True
-    except Exception:
-        # Very broad exception handling because it's always better to
-        # fall back to non-colored logs than to break at startup.
-        pass
-    return False
-
-
-def _safe_unicode(s):
-    try:
-        return _unicode(s)
-    except UnicodeDecodeError:
-        return repr(s)
-
-
-class LogFormatter(logging.Formatter):
-    """Log formatter used in Tornado.
-
-    Key features of this formatter are:
-
-    * Color support when logging to a terminal that supports it.
-    * Timestamps on every log line.
-    * Robust against str/bytes encoding problems.
-
-    This formatter is enabled automatically by
-    `tornado.options.parse_command_line` or `tornado.options.parse_config_file`
-    (unless ``--logging=none`` is used).
-
-    Color support on Windows versions that do not support ANSI color codes is
-    enabled by use of the colorama__ library. Applications that wish to use
-    this must first initialize colorama with a call to ``colorama.init``.
-    See the colorama documentation for details.
-
-    __ https://pypi.python.org/pypi/colorama
-
-    .. versionchanged:: 4.5
-       Added support for ``colorama``. Changed the constructor
-       signature to be compatible with `logging.config.dictConfig`.
-    """
-    DEFAULT_FORMAT = '%(color)s[%(levelname)1.1s %(asctime)s %(module)s:%(lineno)d]%(end_color)s %(message)s'
-    DEFAULT_DATE_FORMAT = '%y%m%d %H:%M:%S'
-    DEFAULT_COLORS = {
-        logging.DEBUG: 4,  # Blue
-        logging.INFO: 2,  # Green
-        logging.WARNING: 3,  # Yellow
-        logging.ERROR: 1,  # Red
-    }
-
-    def __init__(self, fmt=DEFAULT_FORMAT, datefmt=DEFAULT_DATE_FORMAT,
-                 style='%', color=True, colors=DEFAULT_COLORS):
-        r"""
-        :arg bool color: Enables color support.
-        :arg string fmt: Log message format.
-          It will be applied to the attributes dict of log records. The
-          text between ``%(color)s`` and ``%(end_color)s`` will be colored
-          depending on the level if color support is on.
-        :arg dict colors: color mappings from logging level to terminal color
-          code
-        :arg string datefmt: Datetime format.
-          Used for formatting ``(asctime)`` placeholder in ``prefix_fmt``.
-
-        .. versionchanged:: 3.2
-
-           Added ``fmt`` and ``datefmt`` arguments.
-        """
-        logging.Formatter.__init__(self, datefmt=datefmt)
-        self._fmt = fmt
-
-        self._colors = {}
-        if color and _stderr_supports_color():
-            if curses is not None:
-                # The curses module has some str/bytes confusion in
-                # python3.  Until version 3.2.3, most methods return
-                # bytes, but only accept strings.  In addition, we want to
-                # output these strings with the logging module, which
-                # works with unicode strings.  The explicit calls to
-                # unicode() below are harmless in python2 but will do the
-                # right conversion in python 3.
-                fg_color = (curses.tigetstr("setaf") or
-                            curses.tigetstr("setf") or "")
-                if (3, 0) < sys.version_info < (3, 2, 3):
-                    fg_color = unicode_type(fg_color, "ascii")
-
-                for levelno, code in colors.items():
-                    self._colors[levelno] = unicode_type(curses.tparm(fg_color, code), "ascii")
-                self._normal = unicode_type(curses.tigetstr("sgr0"), "ascii")
-            else:
-                # If curses is not present (currently we'll only get here for
-                # colorama on windows), assume hard-coded ANSI color codes.
-                for levelno, code in colors.items():
-                    self._colors[levelno] = '\033[2;3%dm' % code
-                self._normal = '\033[0m'
-        else:
-            self._normal = ''
-
-    def format(self, record):
-        try:
-            message = record.getMessage()
-            assert isinstance(message, basestring_type)  # guaranteed by logging
-            # Encoding notes:  The logging module prefers to work with character
-            # strings, but only enforces that log messages are instances of
-            # basestring.  In python 2, non-ascii bytestrings will make
-            # their way through the logging framework until they blow up with
-            # an unhelpful decoding error (with this formatter it happens
-            # when we attach the prefix, but there are other opportunities for
-            # exceptions further along in the framework).
-            #
-            # If a byte string makes it this far, convert it to unicode to
-            # ensure it will make it out to the logs.  Use repr() as a fallback
-            # to ensure that all byte strings can be converted successfully,
-            # but don't do it by default so we don't add extra quotes to ascii
-            # bytestrings.  This is a bit of a hacky place to do this, but
-            # it's worth it since the encoding errors that would otherwise
-            # result are so useless (and tornado is fond of using utf8-encoded
-            # byte strings whereever possible).
-            record.message = _safe_unicode(message)
-        except Exception as e:
-            record.message = "Bad message (%r): %r" % (e, record.__dict__)
-
-        record.asctime = self.formatTime(record, self.datefmt)
-
-        if record.levelno in self._colors:
-            record.color = self._colors[record.levelno]
-            record.end_color = self._normal
-        else:
-            record.color = record.end_color = ''
-
-        formatted = self._fmt % record.__dict__
-
-        if record.exc_info:
-            if not record.exc_text:
-                record.exc_text = self.formatException(record.exc_info)
-        if record.exc_text:
-            # exc_text contains multiple lines.  We need to _safe_unicode
-            # each line separately so that non-utf8 bytes don't cause
-            # all the newlines to turn into '\n'.
-            lines = [formatted.rstrip()]
-            lines.extend(_safe_unicode(ln) for ln in record.exc_text.split('\n'))
-            formatted = '\n'.join(lines)
-        return formatted.replace("\n", "\n    ")
-
-
-def enable_pretty_logging(options=None, logger=None):
-    """Turns on formatted logging output as configured.
-
-    This is called automatically by `tornado.options.parse_command_line`
-    and `tornado.options.parse_config_file`.
-    """
-    if options is None:
-        import tornado.options
-        options = tornado.options.options
-    if options.logging is None or options.logging.lower() == 'none':
-        return
-    if logger is None:
-        logger = logging.getLogger()
-    logger.setLevel(getattr(logging, options.logging.upper()))
-    if options.log_file_prefix:
-        rotate_mode = options.log_rotate_mode
-        if rotate_mode == 'size':
-            channel = logging.handlers.RotatingFileHandler(
-                filename=options.log_file_prefix,
-                maxBytes=options.log_file_max_size,
-                backupCount=options.log_file_num_backups)
-        elif rotate_mode == 'time':
-            channel = logging.handlers.TimedRotatingFileHandler(
-                filename=options.log_file_prefix,
-                when=options.log_rotate_when,
-                interval=options.log_rotate_interval,
-                backupCount=options.log_file_num_backups)
-        else:
-            error_message = 'The value of log_rotate_mode option should be ' +\
-                            '"size" or "time", not "%s".' % rotate_mode
-            raise ValueError(error_message)
-        channel.setFormatter(LogFormatter(color=False))
-        logger.addHandler(channel)
-
-    if (options.log_to_stderr or
-            (options.log_to_stderr is None and not logger.handlers)):
-        # Set up color if we are in a tty and curses is installed
-        channel = logging.StreamHandler()
-        channel.setFormatter(LogFormatter())
-        logger.addHandler(channel)
-
-
-def define_logging_options(options=None):
-    """Add logging-related flags to ``options``.
-
-    These options are present automatically on the default options instance;
-    this method is only necessary if you have created your own `.OptionParser`.
-
-    .. versionadded:: 4.2
-        This function existed in prior versions but was broken and undocumented until 4.2.
-    """
-    if options is None:
-        # late import to prevent cycle
-        import tornado.options
-        options = tornado.options.options
-    options.define("logging", default="info",
-                   help=("Set the Python log level. If 'none', tornado won't touch the "
-                         "logging configuration."),
-                   metavar="debug|info|warning|error|none")
-    options.define("log_to_stderr", type=bool, default=None,
-                   help=("Send log output to stderr (colorized if possible). "
-                         "By default use stderr if --log_file_prefix is not set and "
-                         "no other logging is configured."))
-    options.define("log_file_prefix", type=str, default=None, metavar="PATH",
-                   help=("Path prefix for log files. "
-                         "Note that if you are running multiple tornado processes, "
-                         "log_file_prefix must be different for each of them (e.g. "
-                         "include the port number)"))
-    options.define("log_file_max_size", type=int, default=100 * 1000 * 1000,
-                   help="max size of log files before rollover")
-    options.define("log_file_num_backups", type=int, default=10,
-                   help="number of log files to keep")
-
-    options.define("log_rotate_when", type=str, default='midnight',
-                   help=("specify the type of TimedRotatingFileHandler interval "
-                         "other options:('S', 'M', 'H', 'D', 'W0'-'W6')"))
-    options.define("log_rotate_interval", type=int, default=1,
-                   help="The interval value of timed rotating")
-
-    options.define("log_rotate_mode", type=str, default='size',
-                   help="The mode of rotating files(time or size)")
-
-    options.add_parse_callback(lambda: enable_pretty_logging(options))
+#!/usr/bin/env python 
+# 
+# Copyright 2012 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+"""Logging support for Tornado. 
+ 
+Tornado uses three logger streams: 
+ 
+* ``tornado.access``: Per-request logging for Tornado's HTTP servers (and 
+  potentially other servers in the future) 
+* ``tornado.application``: Logging of errors from application code (i.e. 
+  uncaught exceptions from callbacks) 
+* ``tornado.general``: General-purpose logging, including any errors 
+  or warnings from Tornado itself. 
+ 
+These streams may be configured independently using the standard library's 
+`logging` module.  For example, you may wish to send ``tornado.access`` logs 
+to a separate file for analysis. 
+""" 
+from __future__ import absolute_import, division, print_function 
+ 
+import logging 
+import logging.handlers 
+import sys 
+ 
+from tornado.escape import _unicode 
+from tornado.util import unicode_type, basestring_type 
+ 
+try: 
+    import colorama 
+except ImportError: 
+    colorama = None 
+ 
+try: 
+    import curses  # type: ignore 
+except ImportError: 
+    curses = None 
+ 
+# Logger objects for internal tornado use 
+access_log = logging.getLogger("tornado.access") 
+app_log = logging.getLogger("tornado.application") 
+gen_log = logging.getLogger("tornado.general") 
+ 
+ 
+def _stderr_supports_color(): 
+    try: 
+        if hasattr(sys.stderr, 'isatty') and sys.stderr.isatty(): 
+            if curses: 
+                curses.setupterm() 
+                if curses.tigetnum("colors") > 0: 
+                    return True 
+            elif colorama: 
+                if sys.stderr is getattr(colorama.initialise, 'wrapped_stderr', 
+                                         object()): 
+                    return True 
+    except Exception: 
+        # Very broad exception handling because it's always better to 
+        # fall back to non-colored logs than to break at startup. 
+        pass 
+    return False 
+ 
+ 
+def _safe_unicode(s): 
+    try: 
+        return _unicode(s) 
+    except UnicodeDecodeError: 
+        return repr(s) 
+ 
+ 
+class LogFormatter(logging.Formatter): 
+    """Log formatter used in Tornado. 
+ 
+    Key features of this formatter are: 
+ 
+    * Color support when logging to a terminal that supports it. 
+    * Timestamps on every log line. 
+    * Robust against str/bytes encoding problems. 
+ 
+    This formatter is enabled automatically by 
+    `tornado.options.parse_command_line` or `tornado.options.parse_config_file` 
+    (unless ``--logging=none`` is used). 
+ 
+    Color support on Windows versions that do not support ANSI color codes is 
+    enabled by use of the colorama__ library. Applications that wish to use 
+    this must first initialize colorama with a call to ``colorama.init``. 
+    See the colorama documentation for details. 
+ 
+    __ https://pypi.python.org/pypi/colorama 
+ 
+    .. versionchanged:: 4.5 
+       Added support for ``colorama``. Changed the constructor 
+       signature to be compatible with `logging.config.dictConfig`. 
+    """ 
+    DEFAULT_FORMAT = '%(color)s[%(levelname)1.1s %(asctime)s %(module)s:%(lineno)d]%(end_color)s %(message)s' 
+    DEFAULT_DATE_FORMAT = '%y%m%d %H:%M:%S' 
+    DEFAULT_COLORS = { 
+        logging.DEBUG: 4,  # Blue 
+        logging.INFO: 2,  # Green 
+        logging.WARNING: 3,  # Yellow 
+        logging.ERROR: 1,  # Red 
+    } 
+ 
+    def __init__(self, fmt=DEFAULT_FORMAT, datefmt=DEFAULT_DATE_FORMAT, 
+                 style='%', color=True, colors=DEFAULT_COLORS): 
+        r""" 
+        :arg bool color: Enables color support. 
+        :arg string fmt: Log message format. 
+          It will be applied to the attributes dict of log records. The 
+          text between ``%(color)s`` and ``%(end_color)s`` will be colored 
+          depending on the level if color support is on. 
+        :arg dict colors: color mappings from logging level to terminal color 
+          code 
+        :arg string datefmt: Datetime format. 
+          Used for formatting ``(asctime)`` placeholder in ``prefix_fmt``. 
+ 
+        .. versionchanged:: 3.2 
+ 
+           Added ``fmt`` and ``datefmt`` arguments. 
+        """ 
+        logging.Formatter.__init__(self, datefmt=datefmt) 
+        self._fmt = fmt 
+ 
+        self._colors = {} 
+        if color and _stderr_supports_color(): 
+            if curses is not None: 
+                # The curses module has some str/bytes confusion in 
+                # python3.  Until version 3.2.3, most methods return 
+                # bytes, but only accept strings.  In addition, we want to 
+                # output these strings with the logging module, which 
+                # works with unicode strings.  The explicit calls to 
+                # unicode() below are harmless in python2 but will do the 
+                # right conversion in python 3. 
+                fg_color = (curses.tigetstr("setaf") or 
+                            curses.tigetstr("setf") or "") 
+                if (3, 0) < sys.version_info < (3, 2, 3): 
+                    fg_color = unicode_type(fg_color, "ascii") 
+ 
+                for levelno, code in colors.items(): 
+                    self._colors[levelno] = unicode_type(curses.tparm(fg_color, code), "ascii") 
+                self._normal = unicode_type(curses.tigetstr("sgr0"), "ascii") 
+            else: 
+                # If curses is not present (currently we'll only get here for 
+                # colorama on windows), assume hard-coded ANSI color codes. 
+                for levelno, code in colors.items(): 
+                    self._colors[levelno] = '\033[2;3%dm' % code 
+                self._normal = '\033[0m' 
+        else: 
+            self._normal = '' 
+ 
+    def format(self, record): 
+        try: 
+            message = record.getMessage() 
+            assert isinstance(message, basestring_type)  # guaranteed by logging 
+            # Encoding notes:  The logging module prefers to work with character 
+            # strings, but only enforces that log messages are instances of 
+            # basestring.  In python 2, non-ascii bytestrings will make 
+            # their way through the logging framework until they blow up with 
+            # an unhelpful decoding error (with this formatter it happens 
+            # when we attach the prefix, but there are other opportunities for 
+            # exceptions further along in the framework). 
+            # 
+            # If a byte string makes it this far, convert it to unicode to 
+            # ensure it will make it out to the logs.  Use repr() as a fallback 
+            # to ensure that all byte strings can be converted successfully, 
+            # but don't do it by default so we don't add extra quotes to ascii 
+            # bytestrings.  This is a bit of a hacky place to do this, but 
+            # it's worth it since the encoding errors that would otherwise 
+            # result are so useless (and tornado is fond of using utf8-encoded 
+            # byte strings whereever possible). 
+            record.message = _safe_unicode(message) 
+        except Exception as e: 
+            record.message = "Bad message (%r): %r" % (e, record.__dict__) 
+ 
+        record.asctime = self.formatTime(record, self.datefmt) 
+ 
+        if record.levelno in self._colors: 
+            record.color = self._colors[record.levelno] 
+            record.end_color = self._normal 
+        else: 
+            record.color = record.end_color = '' 
+ 
+        formatted = self._fmt % record.__dict__ 
+ 
+        if record.exc_info: 
+            if not record.exc_text: 
+                record.exc_text = self.formatException(record.exc_info) 
+        if record.exc_text: 
+            # exc_text contains multiple lines.  We need to _safe_unicode 
+            # each line separately so that non-utf8 bytes don't cause 
+            # all the newlines to turn into '\n'. 
+            lines = [formatted.rstrip()] 
+            lines.extend(_safe_unicode(ln) for ln in record.exc_text.split('\n')) 
+            formatted = '\n'.join(lines) 
+        return formatted.replace("\n", "\n    ") 
+ 
+ 
+def enable_pretty_logging(options=None, logger=None): 
+    """Turns on formatted logging output as configured. 
+ 
+    This is called automatically by `tornado.options.parse_command_line` 
+    and `tornado.options.parse_config_file`. 
+    """ 
+    if options is None: 
+        import tornado.options 
+        options = tornado.options.options 
+    if options.logging is None or options.logging.lower() == 'none': 
+        return 
+    if logger is None: 
+        logger = logging.getLogger() 
+    logger.setLevel(getattr(logging, options.logging.upper())) 
+    if options.log_file_prefix: 
+        rotate_mode = options.log_rotate_mode 
+        if rotate_mode == 'size': 
+            channel = logging.handlers.RotatingFileHandler( 
+                filename=options.log_file_prefix, 
+                maxBytes=options.log_file_max_size, 
+                backupCount=options.log_file_num_backups) 
+        elif rotate_mode == 'time': 
+            channel = logging.handlers.TimedRotatingFileHandler( 
+                filename=options.log_file_prefix, 
+                when=options.log_rotate_when, 
+                interval=options.log_rotate_interval, 
+                backupCount=options.log_file_num_backups) 
+        else: 
+            error_message = 'The value of log_rotate_mode option should be ' +\ 
+                            '"size" or "time", not "%s".' % rotate_mode 
+            raise ValueError(error_message) 
+        channel.setFormatter(LogFormatter(color=False)) 
+        logger.addHandler(channel) 
+ 
+    if (options.log_to_stderr or 
+            (options.log_to_stderr is None and not logger.handlers)): 
+        # Set up color if we are in a tty and curses is installed 
+        channel = logging.StreamHandler() 
+        channel.setFormatter(LogFormatter()) 
+        logger.addHandler(channel) 
+ 
+ 
+def define_logging_options(options=None): 
+    """Add logging-related flags to ``options``. 
+ 
+    These options are present automatically on the default options instance; 
+    this method is only necessary if you have created your own `.OptionParser`. 
+ 
+    .. versionadded:: 4.2 
+        This function existed in prior versions but was broken and undocumented until 4.2. 
+    """ 
+    if options is None: 
+        # late import to prevent cycle 
+        import tornado.options 
+        options = tornado.options.options 
+    options.define("logging", default="info", 
+                   help=("Set the Python log level. If 'none', tornado won't touch the " 
+                         "logging configuration."), 
+                   metavar="debug|info|warning|error|none") 
+    options.define("log_to_stderr", type=bool, default=None, 
+                   help=("Send log output to stderr (colorized if possible). " 
+                         "By default use stderr if --log_file_prefix is not set and " 
+                         "no other logging is configured.")) 
+    options.define("log_file_prefix", type=str, default=None, metavar="PATH", 
+                   help=("Path prefix for log files. " 
+                         "Note that if you are running multiple tornado processes, " 
+                         "log_file_prefix must be different for each of them (e.g. " 
+                         "include the port number)")) 
+    options.define("log_file_max_size", type=int, default=100 * 1000 * 1000, 
+                   help="max size of log files before rollover") 
+    options.define("log_file_num_backups", type=int, default=10, 
+                   help="number of log files to keep") 
+ 
+    options.define("log_rotate_when", type=str, default='midnight', 
+                   help=("specify the type of TimedRotatingFileHandler interval " 
+                         "other options:('S', 'M', 'H', 'D', 'W0'-'W6')")) 
+    options.define("log_rotate_interval", type=int, default=1, 
+                   help="The interval value of timed rotating") 
+ 
+    options.define("log_rotate_mode", type=str, default='size', 
+                   help="The mode of rotating files(time or size)") 
+ 
+    options.add_parse_callback(lambda: enable_pretty_logging(options)) 
diff --git a/contrib/python/tornado/tornado-4/tornado/netutil.py b/contrib/python/tornado/tornado-4/tornado/netutil.py
index 59df1435ea..e74434234a 100644
--- a/contrib/python/tornado/tornado-4/tornado/netutil.py
+++ b/contrib/python/tornado/tornado-4/tornado/netutil.py
@@ -1,531 +1,531 @@
-#!/usr/bin/env python
-#
-# Copyright 2011 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Miscellaneous network utility code."""
-
-from __future__ import absolute_import, division, print_function
-
-import errno
-import os
-import sys
-import socket
-import stat
-
-from tornado.concurrent import dummy_executor, run_on_executor
-from tornado.ioloop import IOLoop
-from tornado.platform.auto import set_close_exec
-from tornado.util import PY3, Configurable, errno_from_exception
-
-try:
-    import ssl
-except ImportError:
-    # ssl is not available on Google App Engine
-    ssl = None
-
-try:
-    import certifi
-except ImportError:
-    # certifi is optional as long as we have ssl.create_default_context.
-    if ssl is None or hasattr(ssl, 'create_default_context'):
-        certifi = None
-    else:
-        raise
-
-if PY3:
-    xrange = range
-
-if hasattr(ssl, 'match_hostname') and hasattr(ssl, 'CertificateError'):  # python 3.2+
-    ssl_match_hostname = ssl.match_hostname
-    SSLCertificateError = ssl.CertificateError
-elif ssl is None:
-    ssl_match_hostname = SSLCertificateError = None  # type: ignore
-else:
-    import backports.ssl_match_hostname
-    ssl_match_hostname = backports.ssl_match_hostname.match_hostname
-    SSLCertificateError = backports.ssl_match_hostname.CertificateError  # type: ignore
-
-if hasattr(ssl, 'SSLContext'):
-    if hasattr(ssl, 'create_default_context'):
-        # Python 2.7.9+, 3.4+
-        # Note that the naming of ssl.Purpose is confusing; the purpose
-        # of a context is to authentiate the opposite side of the connection.
-        _client_ssl_defaults = ssl.create_default_context(
-            ssl.Purpose.SERVER_AUTH)
-        # load ca certs bundled with binary
-        _client_ssl_defaults.load_verify_locations(certifi.where())
-        _server_ssl_defaults = ssl.create_default_context(
-            ssl.Purpose.CLIENT_AUTH)
-    else:
-        # Python 3.2-3.3
-        _client_ssl_defaults = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
-        _client_ssl_defaults.verify_mode = ssl.CERT_REQUIRED
-        _client_ssl_defaults.load_verify_locations(certifi.where())
-        _server_ssl_defaults = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
-        if hasattr(ssl, 'OP_NO_COMPRESSION'):
-            # Disable TLS compression to avoid CRIME and related attacks.
-            # This constant wasn't added until python 3.3.
-            _client_ssl_defaults.options |= ssl.OP_NO_COMPRESSION
-            _server_ssl_defaults.options |= ssl.OP_NO_COMPRESSION
-
-elif ssl:
-    # Python 2.6-2.7.8
-    _client_ssl_defaults = dict(cert_reqs=ssl.CERT_REQUIRED,
-                                ca_certs=certifi.where())
-    _server_ssl_defaults = {}
-else:
-    # Google App Engine
-    _client_ssl_defaults = dict(cert_reqs=None,
-                                ca_certs=None)
-    _server_ssl_defaults = {}
-
-# ThreadedResolver runs getaddrinfo on a thread. If the hostname is unicode,
-# getaddrinfo attempts to import encodings.idna. If this is done at
-# module-import time, the import lock is already held by the main thread,
-# leading to deadlock. Avoid it by caching the idna encoder on the main
-# thread now.
-u'foo'.encode('idna')
-
-# For undiagnosed reasons, 'latin1' codec may also need to be preloaded.
-u'foo'.encode('latin1')
-
-# These errnos indicate that a non-blocking operation must be retried
-# at a later time.  On most platforms they're the same value, but on
-# some they differ.
-_ERRNO_WOULDBLOCK = (errno.EWOULDBLOCK, errno.EAGAIN)
-
-if hasattr(errno, "WSAEWOULDBLOCK"):
-    _ERRNO_WOULDBLOCK += (errno.WSAEWOULDBLOCK,)  # type: ignore
-
-# Default backlog used when calling sock.listen()
-_DEFAULT_BACKLOG = 128
-
-
-def bind_sockets(port, address=None, family=socket.AF_UNSPEC,
-                 backlog=_DEFAULT_BACKLOG, flags=None, reuse_port=False):
-    """Creates listening sockets bound to the given port and address.
-
-    Returns a list of socket objects (multiple sockets are returned if
-    the given address maps to multiple IP addresses, which is most common
-    for mixed IPv4 and IPv6 use).
-
-    Address may be either an IP address or hostname.  If it's a hostname,
-    the server will listen on all IP addresses associated with the
-    name.  Address may be an empty string or None to listen on all
-    available interfaces.  Family may be set to either `socket.AF_INET`
-    or `socket.AF_INET6` to restrict to IPv4 or IPv6 addresses, otherwise
-    both will be used if available.
-
-    The ``backlog`` argument has the same meaning as for
-    `socket.listen() <socket.socket.listen>`.
-
-    ``flags`` is a bitmask of AI_* flags to `~socket.getaddrinfo`, like
-    ``socket.AI_PASSIVE | socket.AI_NUMERICHOST``.
-
-    ``reuse_port`` option sets ``SO_REUSEPORT`` option for every socket
-    in the list. If your platform doesn't support this option ValueError will
-    be raised.
-    """
-    if reuse_port and not hasattr(socket, "SO_REUSEPORT"):
-        raise ValueError("the platform doesn't support SO_REUSEPORT")
-
-    sockets = []
-    if address == "":
-        address = None
-    if not socket.has_ipv6 and family == socket.AF_UNSPEC:
-        # Python can be compiled with --disable-ipv6, which causes
-        # operations on AF_INET6 sockets to fail, but does not
-        # automatically exclude those results from getaddrinfo
-        # results.
-        # http://bugs.python.org/issue16208
-        family = socket.AF_INET
-    if flags is None:
-        flags = socket.AI_PASSIVE
-    bound_port = None
-    for res in set(socket.getaddrinfo(address, port, family, socket.SOCK_STREAM,
-                                      0, flags)):
-        af, socktype, proto, canonname, sockaddr = res
-        if (sys.platform == 'darwin' and address == 'localhost' and
-                af == socket.AF_INET6 and sockaddr[3] != 0):
-            # Mac OS X includes a link-local address fe80::1%lo0 in the
-            # getaddrinfo results for 'localhost'.  However, the firewall
-            # doesn't understand that this is a local address and will
-            # prompt for access (often repeatedly, due to an apparent
-            # bug in its ability to remember granting access to an
-            # application). Skip these addresses.
-            continue
-        try:
-            sock = socket.socket(af, socktype, proto)
-        except socket.error as e:
-            if errno_from_exception(e) == errno.EAFNOSUPPORT:
-                continue
-            raise
-        set_close_exec(sock.fileno())
-        if os.name != 'nt':
-            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        if reuse_port:
-            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
-        if af == socket.AF_INET6:
-            # On linux, ipv6 sockets accept ipv4 too by default,
-            # but this makes it impossible to bind to both
-            # 0.0.0.0 in ipv4 and :: in ipv6.  On other systems,
-            # separate sockets *must* be used to listen for both ipv4
-            # and ipv6.  For consistency, always disable ipv4 on our
-            # ipv6 sockets and use a separate ipv4 socket when needed.
-            #
-            # Python 2.x on windows doesn't have IPPROTO_IPV6.
-            if hasattr(socket, "IPPROTO_IPV6"):
-                sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, 1)
-
-        # automatic port allocation with port=None
-        # should bind on the same port on IPv4 and IPv6
-        host, requested_port = sockaddr[:2]
-        if requested_port == 0 and bound_port is not None:
-            sockaddr = tuple([host, bound_port] + list(sockaddr[2:]))
-
-        sock.setblocking(0)
-        sock.bind(sockaddr)
-        bound_port = sock.getsockname()[1]
-        sock.listen(backlog)
-        sockets.append(sock)
-    return sockets
-
-
-if hasattr(socket, 'AF_UNIX'):
-    def bind_unix_socket(file, mode=0o600, backlog=_DEFAULT_BACKLOG):
-        """Creates a listening unix socket.
-
-        If a socket with the given name already exists, it will be deleted.
-        If any other file with that name exists, an exception will be
-        raised.
-
-        Returns a socket object (not a list of socket objects like
-        `bind_sockets`)
-        """
-        sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-        set_close_exec(sock.fileno())
-        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        sock.setblocking(0)
-        try:
-            st = os.stat(file)
-        except OSError as err:
-            if errno_from_exception(err) != errno.ENOENT:
-                raise
-        else:
-            if stat.S_ISSOCK(st.st_mode):
-                os.remove(file)
-            else:
-                raise ValueError("File %s exists and is not a socket", file)
-        sock.bind(file)
-        os.chmod(file, mode)
-        sock.listen(backlog)
-        return sock
-
-
-def add_accept_handler(sock, callback, io_loop=None):
-    """Adds an `.IOLoop` event handler to accept new connections on ``sock``.
-
-    When a connection is accepted, ``callback(connection, address)`` will
-    be run (``connection`` is a socket object, and ``address`` is the
-    address of the other end of the connection).  Note that this signature
-    is different from the ``callback(fd, events)`` signature used for
-    `.IOLoop` handlers.
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-    """
-    if io_loop is None:
-        io_loop = IOLoop.current()
-
-    def accept_handler(fd, events):
-        # More connections may come in while we're handling callbacks;
-        # to prevent starvation of other tasks we must limit the number
-        # of connections we accept at a time.  Ideally we would accept
-        # up to the number of connections that were waiting when we
-        # entered this method, but this information is not available
-        # (and rearranging this method to call accept() as many times
-        # as possible before running any callbacks would have adverse
-        # effects on load balancing in multiprocess configurations).
-        # Instead, we use the (default) listen backlog as a rough
-        # heuristic for the number of connections we can reasonably
-        # accept at once.
-        for i in xrange(_DEFAULT_BACKLOG):
-            try:
-                connection, address = sock.accept()
-            except socket.error as e:
-                # _ERRNO_WOULDBLOCK indicate we have accepted every
-                # connection that is available.
-                if errno_from_exception(e) in _ERRNO_WOULDBLOCK:
-                    return
-                # ECONNABORTED indicates that there was a connection
-                # but it was closed while still in the accept queue.
-                # (observed on FreeBSD).
-                if errno_from_exception(e) == errno.ECONNABORTED:
-                    continue
-                raise
-            set_close_exec(connection.fileno())
-            callback(connection, address)
-    io_loop.add_handler(sock, accept_handler, IOLoop.READ)
-
-
-def is_valid_ip(ip):
-    """Returns true if the given string is a well-formed IP address.
-
-    Supports IPv4 and IPv6.
-    """
-    if not ip or '\x00' in ip:
-        # getaddrinfo resolves empty strings to localhost, and truncates
-        # on zero bytes.
-        return False
-    try:
-        res = socket.getaddrinfo(ip, 0, socket.AF_UNSPEC,
-                                 socket.SOCK_STREAM,
-                                 0, socket.AI_NUMERICHOST)
-        return bool(res)
-    except socket.gaierror as e:
-        if e.args[0] == socket.EAI_NONAME:
-            return False
-        raise
-    return True
-
-
-class Resolver(Configurable):
-    """Configurable asynchronous DNS resolver interface.
-
-    By default, a blocking implementation is used (which simply calls
-    `socket.getaddrinfo`).  An alternative implementation can be
-    chosen with the `Resolver.configure <.Configurable.configure>`
-    class method::
-
-        Resolver.configure('tornado.netutil.ThreadedResolver')
-
-    The implementations of this interface included with Tornado are
-
-    * `tornado.netutil.BlockingResolver`
-    * `tornado.netutil.ThreadedResolver`
-    * `tornado.netutil.OverrideResolver`
-    * `tornado.platform.twisted.TwistedResolver`
-    * `tornado.platform.caresresolver.CaresResolver`
-    """
-    @classmethod
-    def configurable_base(cls):
-        return Resolver
-
-    @classmethod
-    def configurable_default(cls):
-        return BlockingResolver
-
-    def resolve(self, host, port, family=socket.AF_UNSPEC, callback=None):
-        """Resolves an address.
-
-        The ``host`` argument is a string which may be a hostname or a
-        literal IP address.
-
-        Returns a `.Future` whose result is a list of (family,
-        address) pairs, where address is a tuple suitable to pass to
-        `socket.connect <socket.socket.connect>` (i.e. a ``(host,
-        port)`` pair for IPv4; additional fields may be present for
-        IPv6). If a ``callback`` is passed, it will be run with the
-        result as an argument when it is complete.
-
-        :raises IOError: if the address cannot be resolved.
-
-        .. versionchanged:: 4.4
-           Standardized all implementations to raise `IOError`.
-        """
-        raise NotImplementedError()
-
-    def close(self):
-        """Closes the `Resolver`, freeing any resources used.
-
-        .. versionadded:: 3.1
-
-        """
-        pass
-
-
-class ExecutorResolver(Resolver):
-    """Resolver implementation using a `concurrent.futures.Executor`.
-
-    Use this instead of `ThreadedResolver` when you require additional
-    control over the executor being used.
-
-    The executor will be shut down when the resolver is closed unless
-    ``close_resolver=False``; use this if you want to reuse the same
-    executor elsewhere.
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-    """
-    def initialize(self, io_loop=None, executor=None, close_executor=True):
-        self.io_loop = io_loop or IOLoop.current()
-        if executor is not None:
-            self.executor = executor
-            self.close_executor = close_executor
-        else:
-            self.executor = dummy_executor
-            self.close_executor = False
-
-    def close(self):
-        if self.close_executor:
-            self.executor.shutdown()
-        self.executor = None
-
-    @run_on_executor
-    def resolve(self, host, port, family=socket.AF_UNSPEC):
-        # On Solaris, getaddrinfo fails if the given port is not found
-        # in /etc/services and no socket type is given, so we must pass
-        # one here.  The socket type used here doesn't seem to actually
-        # matter (we discard the one we get back in the results),
-        # so the addresses we return should still be usable with SOCK_DGRAM.
-        addrinfo = socket.getaddrinfo(host, port, family, socket.SOCK_STREAM)
-        results = []
-        for family, socktype, proto, canonname, address in addrinfo:
-            results.append((family, address))
-        return results
-
-
-class BlockingResolver(ExecutorResolver):
-    """Default `Resolver` implementation, using `socket.getaddrinfo`.
-
-    The `.IOLoop` will be blocked during the resolution, although the
-    callback will not be run until the next `.IOLoop` iteration.
-    """
-    def initialize(self, io_loop=None):
-        super(BlockingResolver, self).initialize(io_loop=io_loop)
-
-
-class ThreadedResolver(ExecutorResolver):
-    """Multithreaded non-blocking `Resolver` implementation.
-
-    Requires the `concurrent.futures` package to be installed
-    (available in the standard library since Python 3.2,
-    installable with ``pip install futures`` in older versions).
-
-    The thread pool size can be configured with::
-
-        Resolver.configure('tornado.netutil.ThreadedResolver',
-                           num_threads=10)
-
-    .. versionchanged:: 3.1
-       All ``ThreadedResolvers`` share a single thread pool, whose
-       size is set by the first one to be created.
-    """
-    _threadpool = None  # type: ignore
-    _threadpool_pid = None  # type: int
-
-    def initialize(self, io_loop=None, num_threads=10):
-        threadpool = ThreadedResolver._create_threadpool(num_threads)
-        super(ThreadedResolver, self).initialize(
-            io_loop=io_loop, executor=threadpool, close_executor=False)
-
-    @classmethod
-    def _create_threadpool(cls, num_threads):
-        pid = os.getpid()
-        if cls._threadpool_pid != pid:
-            # Threads cannot survive after a fork, so if our pid isn't what it
-            # was when we created the pool then delete it.
-            cls._threadpool = None
-        if cls._threadpool is None:
-            from concurrent.futures import ThreadPoolExecutor
-            cls._threadpool = ThreadPoolExecutor(num_threads)
-            cls._threadpool_pid = pid
-        return cls._threadpool
-
-
-class OverrideResolver(Resolver):
-    """Wraps a resolver with a mapping of overrides.
-
-    This can be used to make local DNS changes (e.g. for testing)
-    without modifying system-wide settings.
-
-    The mapping can contain either host strings or host-port pairs.
-    """
-    def initialize(self, resolver, mapping):
-        self.resolver = resolver
-        self.mapping = mapping
-
-    def close(self):
-        self.resolver.close()
-
-    def resolve(self, host, port, *args, **kwargs):
-        if (host, port) in self.mapping:
-            host, port = self.mapping[(host, port)]
-        elif host in self.mapping:
-            host = self.mapping[host]
-        return self.resolver.resolve(host, port, *args, **kwargs)
-
-
-# These are the keyword arguments to ssl.wrap_socket that must be translated
-# to their SSLContext equivalents (the other arguments are still passed
-# to SSLContext.wrap_socket).
-_SSL_CONTEXT_KEYWORDS = frozenset(['ssl_version', 'certfile', 'keyfile',
-                                   'cert_reqs', 'ca_certs', 'ciphers'])
-
-
-def ssl_options_to_context(ssl_options):
-    """Try to convert an ``ssl_options`` dictionary to an
-    `~ssl.SSLContext` object.
-
-    The ``ssl_options`` dictionary contains keywords to be passed to
-    `ssl.wrap_socket`.  In Python 2.7.9+, `ssl.SSLContext` objects can
-    be used instead.  This function converts the dict form to its
-    `~ssl.SSLContext` equivalent, and may be used when a component which
-    accepts both forms needs to upgrade to the `~ssl.SSLContext` version
-    to use features like SNI or NPN.
-    """
-    if isinstance(ssl_options, dict):
-        assert all(k in _SSL_CONTEXT_KEYWORDS for k in ssl_options), ssl_options
-    if (not hasattr(ssl, 'SSLContext') or
-            isinstance(ssl_options, ssl.SSLContext)):
-        return ssl_options
-    context = ssl.SSLContext(
-        ssl_options.get('ssl_version', ssl.PROTOCOL_SSLv23))
-    if 'certfile' in ssl_options:
-        context.load_cert_chain(ssl_options['certfile'], ssl_options.get('keyfile', None))
-    if 'cert_reqs' in ssl_options:
-        context.verify_mode = ssl_options['cert_reqs']
-    if 'ca_certs' in ssl_options:
-        context.load_verify_locations(ssl_options['ca_certs'])
-    if 'ciphers' in ssl_options:
-        context.set_ciphers(ssl_options['ciphers'])
-    if hasattr(ssl, 'OP_NO_COMPRESSION'):
-        # Disable TLS compression to avoid CRIME and related attacks.
-        # This constant wasn't added until python 3.3.
-        context.options |= ssl.OP_NO_COMPRESSION
-    return context
-
-
-def ssl_wrap_socket(socket, ssl_options, server_hostname=None, **kwargs):
-    """Returns an ``ssl.SSLSocket`` wrapping the given socket.
-
-    ``ssl_options`` may be either an `ssl.SSLContext` object or a
-    dictionary (as accepted by `ssl_options_to_context`).  Additional
-    keyword arguments are passed to ``wrap_socket`` (either the
-    `~ssl.SSLContext` method or the `ssl` module function as
-    appropriate).
-    """
-    context = ssl_options_to_context(ssl_options)
-    if hasattr(ssl, 'SSLContext') and isinstance(context, ssl.SSLContext):
-        if server_hostname is not None and getattr(ssl, 'HAS_SNI'):
-            # Python doesn't have server-side SNI support so we can't
-            # really unittest this, but it can be manually tested with
-            # python3.2 -m tornado.httpclient https://sni.velox.ch
-            return context.wrap_socket(socket, server_hostname=server_hostname,
-                                       **kwargs)
-        else:
-            return context.wrap_socket(socket, **kwargs)
-    else:
-        return ssl.wrap_socket(socket, **dict(context, **kwargs))  # type: ignore
+#!/usr/bin/env python 
+# 
+# Copyright 2011 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Miscellaneous network utility code.""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import errno 
+import os 
+import sys 
+import socket 
+import stat 
+ 
+from tornado.concurrent import dummy_executor, run_on_executor 
+from tornado.ioloop import IOLoop 
+from tornado.platform.auto import set_close_exec 
+from tornado.util import PY3, Configurable, errno_from_exception 
+ 
+try: 
+    import ssl 
+except ImportError: 
+    # ssl is not available on Google App Engine 
+    ssl = None 
+ 
+try: 
+    import certifi 
+except ImportError: 
+    # certifi is optional as long as we have ssl.create_default_context. 
+    if ssl is None or hasattr(ssl, 'create_default_context'): 
+        certifi = None 
+    else: 
+        raise 
+ 
+if PY3: 
+    xrange = range 
+ 
+if hasattr(ssl, 'match_hostname') and hasattr(ssl, 'CertificateError'):  # python 3.2+ 
+    ssl_match_hostname = ssl.match_hostname 
+    SSLCertificateError = ssl.CertificateError 
+elif ssl is None: 
+    ssl_match_hostname = SSLCertificateError = None  # type: ignore 
+else: 
+    import backports.ssl_match_hostname 
+    ssl_match_hostname = backports.ssl_match_hostname.match_hostname 
+    SSLCertificateError = backports.ssl_match_hostname.CertificateError  # type: ignore 
+ 
+if hasattr(ssl, 'SSLContext'): 
+    if hasattr(ssl, 'create_default_context'): 
+        # Python 2.7.9+, 3.4+ 
+        # Note that the naming of ssl.Purpose is confusing; the purpose 
+        # of a context is to authentiate the opposite side of the connection. 
+        _client_ssl_defaults = ssl.create_default_context( 
+            ssl.Purpose.SERVER_AUTH) 
+        # load ca certs bundled with binary 
+        _client_ssl_defaults.load_verify_locations(certifi.where()) 
+        _server_ssl_defaults = ssl.create_default_context( 
+            ssl.Purpose.CLIENT_AUTH) 
+    else: 
+        # Python 3.2-3.3 
+        _client_ssl_defaults = ssl.SSLContext(ssl.PROTOCOL_SSLv23) 
+        _client_ssl_defaults.verify_mode = ssl.CERT_REQUIRED 
+        _client_ssl_defaults.load_verify_locations(certifi.where()) 
+        _server_ssl_defaults = ssl.SSLContext(ssl.PROTOCOL_SSLv23) 
+        if hasattr(ssl, 'OP_NO_COMPRESSION'): 
+            # Disable TLS compression to avoid CRIME and related attacks. 
+            # This constant wasn't added until python 3.3. 
+            _client_ssl_defaults.options |= ssl.OP_NO_COMPRESSION 
+            _server_ssl_defaults.options |= ssl.OP_NO_COMPRESSION 
+ 
+elif ssl: 
+    # Python 2.6-2.7.8 
+    _client_ssl_defaults = dict(cert_reqs=ssl.CERT_REQUIRED, 
+                                ca_certs=certifi.where()) 
+    _server_ssl_defaults = {} 
+else: 
+    # Google App Engine 
+    _client_ssl_defaults = dict(cert_reqs=None, 
+                                ca_certs=None) 
+    _server_ssl_defaults = {} 
+ 
+# ThreadedResolver runs getaddrinfo on a thread. If the hostname is unicode, 
+# getaddrinfo attempts to import encodings.idna. If this is done at 
+# module-import time, the import lock is already held by the main thread, 
+# leading to deadlock. Avoid it by caching the idna encoder on the main 
+# thread now. 
+u'foo'.encode('idna') 
+ 
+# For undiagnosed reasons, 'latin1' codec may also need to be preloaded. 
+u'foo'.encode('latin1') 
+ 
+# These errnos indicate that a non-blocking operation must be retried 
+# at a later time.  On most platforms they're the same value, but on 
+# some they differ. 
+_ERRNO_WOULDBLOCK = (errno.EWOULDBLOCK, errno.EAGAIN) 
+ 
+if hasattr(errno, "WSAEWOULDBLOCK"): 
+    _ERRNO_WOULDBLOCK += (errno.WSAEWOULDBLOCK,)  # type: ignore 
+ 
+# Default backlog used when calling sock.listen() 
+_DEFAULT_BACKLOG = 128 
+ 
+ 
+def bind_sockets(port, address=None, family=socket.AF_UNSPEC, 
+                 backlog=_DEFAULT_BACKLOG, flags=None, reuse_port=False): 
+    """Creates listening sockets bound to the given port and address. 
+ 
+    Returns a list of socket objects (multiple sockets are returned if 
+    the given address maps to multiple IP addresses, which is most common 
+    for mixed IPv4 and IPv6 use). 
+ 
+    Address may be either an IP address or hostname.  If it's a hostname, 
+    the server will listen on all IP addresses associated with the 
+    name.  Address may be an empty string or None to listen on all 
+    available interfaces.  Family may be set to either `socket.AF_INET` 
+    or `socket.AF_INET6` to restrict to IPv4 or IPv6 addresses, otherwise 
+    both will be used if available. 
+ 
+    The ``backlog`` argument has the same meaning as for 
+    `socket.listen() <socket.socket.listen>`. 
+ 
+    ``flags`` is a bitmask of AI_* flags to `~socket.getaddrinfo`, like 
+    ``socket.AI_PASSIVE | socket.AI_NUMERICHOST``. 
+ 
+    ``reuse_port`` option sets ``SO_REUSEPORT`` option for every socket 
+    in the list. If your platform doesn't support this option ValueError will 
+    be raised. 
+    """ 
+    if reuse_port and not hasattr(socket, "SO_REUSEPORT"): 
+        raise ValueError("the platform doesn't support SO_REUSEPORT") 
+ 
+    sockets = [] 
+    if address == "": 
+        address = None 
+    if not socket.has_ipv6 and family == socket.AF_UNSPEC: 
+        # Python can be compiled with --disable-ipv6, which causes 
+        # operations on AF_INET6 sockets to fail, but does not 
+        # automatically exclude those results from getaddrinfo 
+        # results. 
+        # http://bugs.python.org/issue16208 
+        family = socket.AF_INET 
+    if flags is None: 
+        flags = socket.AI_PASSIVE 
+    bound_port = None 
+    for res in set(socket.getaddrinfo(address, port, family, socket.SOCK_STREAM, 
+                                      0, flags)): 
+        af, socktype, proto, canonname, sockaddr = res 
+        if (sys.platform == 'darwin' and address == 'localhost' and 
+                af == socket.AF_INET6 and sockaddr[3] != 0): 
+            # Mac OS X includes a link-local address fe80::1%lo0 in the 
+            # getaddrinfo results for 'localhost'.  However, the firewall 
+            # doesn't understand that this is a local address and will 
+            # prompt for access (often repeatedly, due to an apparent 
+            # bug in its ability to remember granting access to an 
+            # application). Skip these addresses. 
+            continue 
+        try: 
+            sock = socket.socket(af, socktype, proto) 
+        except socket.error as e: 
+            if errno_from_exception(e) == errno.EAFNOSUPPORT: 
+                continue 
+            raise 
+        set_close_exec(sock.fileno()) 
+        if os.name != 'nt': 
+            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) 
+        if reuse_port: 
+            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1) 
+        if af == socket.AF_INET6: 
+            # On linux, ipv6 sockets accept ipv4 too by default, 
+            # but this makes it impossible to bind to both 
+            # 0.0.0.0 in ipv4 and :: in ipv6.  On other systems, 
+            # separate sockets *must* be used to listen for both ipv4 
+            # and ipv6.  For consistency, always disable ipv4 on our 
+            # ipv6 sockets and use a separate ipv4 socket when needed. 
+            # 
+            # Python 2.x on windows doesn't have IPPROTO_IPV6. 
+            if hasattr(socket, "IPPROTO_IPV6"): 
+                sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, 1) 
+ 
+        # automatic port allocation with port=None 
+        # should bind on the same port on IPv4 and IPv6 
+        host, requested_port = sockaddr[:2] 
+        if requested_port == 0 and bound_port is not None: 
+            sockaddr = tuple([host, bound_port] + list(sockaddr[2:])) 
+ 
+        sock.setblocking(0) 
+        sock.bind(sockaddr) 
+        bound_port = sock.getsockname()[1] 
+        sock.listen(backlog) 
+        sockets.append(sock) 
+    return sockets 
+ 
+ 
+if hasattr(socket, 'AF_UNIX'): 
+    def bind_unix_socket(file, mode=0o600, backlog=_DEFAULT_BACKLOG): 
+        """Creates a listening unix socket. 
+ 
+        If a socket with the given name already exists, it will be deleted. 
+        If any other file with that name exists, an exception will be 
+        raised. 
+ 
+        Returns a socket object (not a list of socket objects like 
+        `bind_sockets`) 
+        """ 
+        sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) 
+        set_close_exec(sock.fileno()) 
+        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) 
+        sock.setblocking(0) 
+        try: 
+            st = os.stat(file) 
+        except OSError as err: 
+            if errno_from_exception(err) != errno.ENOENT: 
+                raise 
+        else: 
+            if stat.S_ISSOCK(st.st_mode): 
+                os.remove(file) 
+            else: 
+                raise ValueError("File %s exists and is not a socket", file) 
+        sock.bind(file) 
+        os.chmod(file, mode) 
+        sock.listen(backlog) 
+        return sock 
+ 
+ 
+def add_accept_handler(sock, callback, io_loop=None): 
+    """Adds an `.IOLoop` event handler to accept new connections on ``sock``. 
+ 
+    When a connection is accepted, ``callback(connection, address)`` will 
+    be run (``connection`` is a socket object, and ``address`` is the 
+    address of the other end of the connection).  Note that this signature 
+    is different from the ``callback(fd, events)`` signature used for 
+    `.IOLoop` handlers. 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+    """ 
+    if io_loop is None: 
+        io_loop = IOLoop.current() 
+ 
+    def accept_handler(fd, events): 
+        # More connections may come in while we're handling callbacks; 
+        # to prevent starvation of other tasks we must limit the number 
+        # of connections we accept at a time.  Ideally we would accept 
+        # up to the number of connections that were waiting when we 
+        # entered this method, but this information is not available 
+        # (and rearranging this method to call accept() as many times 
+        # as possible before running any callbacks would have adverse 
+        # effects on load balancing in multiprocess configurations). 
+        # Instead, we use the (default) listen backlog as a rough 
+        # heuristic for the number of connections we can reasonably 
+        # accept at once. 
+        for i in xrange(_DEFAULT_BACKLOG): 
+            try: 
+                connection, address = sock.accept() 
+            except socket.error as e: 
+                # _ERRNO_WOULDBLOCK indicate we have accepted every 
+                # connection that is available. 
+                if errno_from_exception(e) in _ERRNO_WOULDBLOCK: 
+                    return 
+                # ECONNABORTED indicates that there was a connection 
+                # but it was closed while still in the accept queue. 
+                # (observed on FreeBSD). 
+                if errno_from_exception(e) == errno.ECONNABORTED: 
+                    continue 
+                raise 
+            set_close_exec(connection.fileno()) 
+            callback(connection, address) 
+    io_loop.add_handler(sock, accept_handler, IOLoop.READ) 
+ 
+ 
+def is_valid_ip(ip): 
+    """Returns true if the given string is a well-formed IP address. 
+ 
+    Supports IPv4 and IPv6. 
+    """ 
+    if not ip or '\x00' in ip: 
+        # getaddrinfo resolves empty strings to localhost, and truncates 
+        # on zero bytes. 
+        return False 
+    try: 
+        res = socket.getaddrinfo(ip, 0, socket.AF_UNSPEC, 
+                                 socket.SOCK_STREAM, 
+                                 0, socket.AI_NUMERICHOST) 
+        return bool(res) 
+    except socket.gaierror as e: 
+        if e.args[0] == socket.EAI_NONAME: 
+            return False 
+        raise 
+    return True 
+ 
+ 
+class Resolver(Configurable): 
+    """Configurable asynchronous DNS resolver interface. 
+ 
+    By default, a blocking implementation is used (which simply calls 
+    `socket.getaddrinfo`).  An alternative implementation can be 
+    chosen with the `Resolver.configure <.Configurable.configure>` 
+    class method:: 
+ 
+        Resolver.configure('tornado.netutil.ThreadedResolver') 
+ 
+    The implementations of this interface included with Tornado are 
+ 
+    * `tornado.netutil.BlockingResolver` 
+    * `tornado.netutil.ThreadedResolver` 
+    * `tornado.netutil.OverrideResolver` 
+    * `tornado.platform.twisted.TwistedResolver` 
+    * `tornado.platform.caresresolver.CaresResolver` 
+    """ 
+    @classmethod 
+    def configurable_base(cls): 
+        return Resolver 
+ 
+    @classmethod 
+    def configurable_default(cls): 
+        return BlockingResolver 
+ 
+    def resolve(self, host, port, family=socket.AF_UNSPEC, callback=None): 
+        """Resolves an address. 
+ 
+        The ``host`` argument is a string which may be a hostname or a 
+        literal IP address. 
+ 
+        Returns a `.Future` whose result is a list of (family, 
+        address) pairs, where address is a tuple suitable to pass to 
+        `socket.connect <socket.socket.connect>` (i.e. a ``(host, 
+        port)`` pair for IPv4; additional fields may be present for 
+        IPv6). If a ``callback`` is passed, it will be run with the 
+        result as an argument when it is complete. 
+ 
+        :raises IOError: if the address cannot be resolved. 
+ 
+        .. versionchanged:: 4.4 
+           Standardized all implementations to raise `IOError`. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def close(self): 
+        """Closes the `Resolver`, freeing any resources used. 
+ 
+        .. versionadded:: 3.1 
+ 
+        """ 
+        pass 
+ 
+ 
+class ExecutorResolver(Resolver): 
+    """Resolver implementation using a `concurrent.futures.Executor`. 
+ 
+    Use this instead of `ThreadedResolver` when you require additional 
+    control over the executor being used. 
+ 
+    The executor will be shut down when the resolver is closed unless 
+    ``close_resolver=False``; use this if you want to reuse the same 
+    executor elsewhere. 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+    """ 
+    def initialize(self, io_loop=None, executor=None, close_executor=True): 
+        self.io_loop = io_loop or IOLoop.current() 
+        if executor is not None: 
+            self.executor = executor 
+            self.close_executor = close_executor 
+        else: 
+            self.executor = dummy_executor 
+            self.close_executor = False 
+ 
+    def close(self): 
+        if self.close_executor: 
+            self.executor.shutdown() 
+        self.executor = None 
+ 
+    @run_on_executor 
+    def resolve(self, host, port, family=socket.AF_UNSPEC): 
+        # On Solaris, getaddrinfo fails if the given port is not found 
+        # in /etc/services and no socket type is given, so we must pass 
+        # one here.  The socket type used here doesn't seem to actually 
+        # matter (we discard the one we get back in the results), 
+        # so the addresses we return should still be usable with SOCK_DGRAM. 
+        addrinfo = socket.getaddrinfo(host, port, family, socket.SOCK_STREAM) 
+        results = [] 
+        for family, socktype, proto, canonname, address in addrinfo: 
+            results.append((family, address)) 
+        return results 
+ 
+ 
+class BlockingResolver(ExecutorResolver): 
+    """Default `Resolver` implementation, using `socket.getaddrinfo`. 
+ 
+    The `.IOLoop` will be blocked during the resolution, although the 
+    callback will not be run until the next `.IOLoop` iteration. 
+    """ 
+    def initialize(self, io_loop=None): 
+        super(BlockingResolver, self).initialize(io_loop=io_loop) 
+ 
+ 
+class ThreadedResolver(ExecutorResolver): 
+    """Multithreaded non-blocking `Resolver` implementation. 
+ 
+    Requires the `concurrent.futures` package to be installed 
+    (available in the standard library since Python 3.2, 
+    installable with ``pip install futures`` in older versions). 
+ 
+    The thread pool size can be configured with:: 
+ 
+        Resolver.configure('tornado.netutil.ThreadedResolver', 
+                           num_threads=10) 
+ 
+    .. versionchanged:: 3.1 
+       All ``ThreadedResolvers`` share a single thread pool, whose 
+       size is set by the first one to be created. 
+    """ 
+    _threadpool = None  # type: ignore 
+    _threadpool_pid = None  # type: int 
+ 
+    def initialize(self, io_loop=None, num_threads=10): 
+        threadpool = ThreadedResolver._create_threadpool(num_threads) 
+        super(ThreadedResolver, self).initialize( 
+            io_loop=io_loop, executor=threadpool, close_executor=False) 
+ 
+    @classmethod 
+    def _create_threadpool(cls, num_threads): 
+        pid = os.getpid() 
+        if cls._threadpool_pid != pid: 
+            # Threads cannot survive after a fork, so if our pid isn't what it 
+            # was when we created the pool then delete it. 
+            cls._threadpool = None 
+        if cls._threadpool is None: 
+            from concurrent.futures import ThreadPoolExecutor 
+            cls._threadpool = ThreadPoolExecutor(num_threads) 
+            cls._threadpool_pid = pid 
+        return cls._threadpool 
+ 
+ 
+class OverrideResolver(Resolver): 
+    """Wraps a resolver with a mapping of overrides. 
+ 
+    This can be used to make local DNS changes (e.g. for testing) 
+    without modifying system-wide settings. 
+ 
+    The mapping can contain either host strings or host-port pairs. 
+    """ 
+    def initialize(self, resolver, mapping): 
+        self.resolver = resolver 
+        self.mapping = mapping 
+ 
+    def close(self): 
+        self.resolver.close() 
+ 
+    def resolve(self, host, port, *args, **kwargs): 
+        if (host, port) in self.mapping: 
+            host, port = self.mapping[(host, port)] 
+        elif host in self.mapping: 
+            host = self.mapping[host] 
+        return self.resolver.resolve(host, port, *args, **kwargs) 
+ 
+ 
+# These are the keyword arguments to ssl.wrap_socket that must be translated 
+# to their SSLContext equivalents (the other arguments are still passed 
+# to SSLContext.wrap_socket). 
+_SSL_CONTEXT_KEYWORDS = frozenset(['ssl_version', 'certfile', 'keyfile', 
+                                   'cert_reqs', 'ca_certs', 'ciphers']) 
+ 
+ 
+def ssl_options_to_context(ssl_options): 
+    """Try to convert an ``ssl_options`` dictionary to an 
+    `~ssl.SSLContext` object. 
+ 
+    The ``ssl_options`` dictionary contains keywords to be passed to 
+    `ssl.wrap_socket`.  In Python 2.7.9+, `ssl.SSLContext` objects can 
+    be used instead.  This function converts the dict form to its 
+    `~ssl.SSLContext` equivalent, and may be used when a component which 
+    accepts both forms needs to upgrade to the `~ssl.SSLContext` version 
+    to use features like SNI or NPN. 
+    """ 
+    if isinstance(ssl_options, dict): 
+        assert all(k in _SSL_CONTEXT_KEYWORDS for k in ssl_options), ssl_options 
+    if (not hasattr(ssl, 'SSLContext') or 
+            isinstance(ssl_options, ssl.SSLContext)): 
+        return ssl_options 
+    context = ssl.SSLContext( 
+        ssl_options.get('ssl_version', ssl.PROTOCOL_SSLv23)) 
+    if 'certfile' in ssl_options: 
+        context.load_cert_chain(ssl_options['certfile'], ssl_options.get('keyfile', None)) 
+    if 'cert_reqs' in ssl_options: 
+        context.verify_mode = ssl_options['cert_reqs'] 
+    if 'ca_certs' in ssl_options: 
+        context.load_verify_locations(ssl_options['ca_certs']) 
+    if 'ciphers' in ssl_options: 
+        context.set_ciphers(ssl_options['ciphers']) 
+    if hasattr(ssl, 'OP_NO_COMPRESSION'): 
+        # Disable TLS compression to avoid CRIME and related attacks. 
+        # This constant wasn't added until python 3.3. 
+        context.options |= ssl.OP_NO_COMPRESSION 
+    return context 
+ 
+ 
+def ssl_wrap_socket(socket, ssl_options, server_hostname=None, **kwargs): 
+    """Returns an ``ssl.SSLSocket`` wrapping the given socket. 
+ 
+    ``ssl_options`` may be either an `ssl.SSLContext` object or a 
+    dictionary (as accepted by `ssl_options_to_context`).  Additional 
+    keyword arguments are passed to ``wrap_socket`` (either the 
+    `~ssl.SSLContext` method or the `ssl` module function as 
+    appropriate). 
+    """ 
+    context = ssl_options_to_context(ssl_options) 
+    if hasattr(ssl, 'SSLContext') and isinstance(context, ssl.SSLContext): 
+        if server_hostname is not None and getattr(ssl, 'HAS_SNI'): 
+            # Python doesn't have server-side SNI support so we can't 
+            # really unittest this, but it can be manually tested with 
+            # python3.2 -m tornado.httpclient https://sni.velox.ch 
+            return context.wrap_socket(socket, server_hostname=server_hostname, 
+                                       **kwargs) 
+        else: 
+            return context.wrap_socket(socket, **kwargs) 
+    else: 
+        return ssl.wrap_socket(socket, **dict(context, **kwargs))  # type: ignore 
diff --git a/contrib/python/tornado/tornado-4/tornado/options.py b/contrib/python/tornado/tornado-4/tornado/options.py
index 707fbd35ee..ffaaba6209 100644
--- a/contrib/python/tornado/tornado-4/tornado/options.py
+++ b/contrib/python/tornado/tornado-4/tornado/options.py
@@ -1,594 +1,594 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""A command line parsing module that lets modules define their own options.
-
-Each module defines its own options which are added to the global
-option namespace, e.g.::
-
-    from tornado.options import define, options
-
-    define("mysql_host", default="127.0.0.1:3306", help="Main user DB")
-    define("memcache_hosts", default="127.0.0.1:11011", multiple=True,
-           help="Main user memcache servers")
-
-    def connect():
-        db = database.Connection(options.mysql_host)
-        ...
-
-The ``main()`` method of your application does not need to be aware of all of
-the options used throughout your program; they are all automatically loaded
-when the modules are loaded.  However, all modules that define options
-must have been imported before the command line is parsed.
-
-Your ``main()`` method can parse the command line or parse a config file with
-either::
-
-    tornado.options.parse_command_line()
-    # or
-    tornado.options.parse_config_file("/etc/server.conf")
-
-.. note:
-
-   When using tornado.options.parse_command_line or
-   tornado.options.parse_config_file, the only options that are set are
-   ones that were previously defined with tornado.options.define.
-
-Command line formats are what you would expect (``--myoption=myvalue``).
-Config files are just Python files. Global names become options, e.g.::
-
-    myoption = "myvalue"
-    myotheroption = "myothervalue"
-
-We support `datetimes <datetime.datetime>`, `timedeltas
-<datetime.timedelta>`, ints, and floats (just pass a ``type`` kwarg to
-`define`). We also accept multi-value options. See the documentation for
-`define()` below.
-
-`tornado.options.options` is a singleton instance of `OptionParser`, and
-the top-level functions in this module (`define`, `parse_command_line`, etc)
-simply call methods on it.  You may create additional `OptionParser`
-instances to define isolated sets of options, such as for subcommands.
-
-.. note::
-
-   By default, several options are defined that will configure the
-   standard `logging` module when `parse_command_line` or `parse_config_file`
-   are called.  If you want Tornado to leave the logging configuration
-   alone so you can manage it yourself, either pass ``--logging=none``
-   on the command line or do the following to disable it in code::
-
-       from tornado.options import options, parse_command_line
-       options.logging = None
-       parse_command_line()
-
-.. versionchanged:: 4.3
-   Dashes and underscores are fully interchangeable in option names;
-   options can be defined, set, and read with any mix of the two.
-   Dashes are typical for command-line usage while config files require
-   underscores.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import datetime
-import numbers
-import re
-import sys
-import os
-import textwrap
-
-from tornado.escape import _unicode, native_str
-from tornado.log import define_logging_options
-from tornado import stack_context
-from tornado.util import basestring_type, exec_in
-
-
-class Error(Exception):
-    """Exception raised by errors in the options module."""
-    pass
-
-
-class OptionParser(object):
-    """A collection of options, a dictionary with object-like access.
-
-    Normally accessed via static functions in the `tornado.options` module,
-    which reference a global instance.
-    """
-    def __init__(self):
-        # we have to use self.__dict__ because we override setattr.
-        self.__dict__['_options'] = {}
-        self.__dict__['_parse_callbacks'] = []
-        self.define("help", type=bool, help="show this help information",
-                    callback=self._help_callback)
-
-    def _normalize_name(self, name):
-        return name.replace('_', '-')
-
-    def __getattr__(self, name):
-        name = self._normalize_name(name)
-        if isinstance(self._options.get(name), _Option):
-            return self._options[name].value()
-        raise AttributeError("Unrecognized option %r" % name)
-
-    def __setattr__(self, name, value):
-        name = self._normalize_name(name)
-        if isinstance(self._options.get(name), _Option):
-            return self._options[name].set(value)
-        raise AttributeError("Unrecognized option %r" % name)
-
-    def __iter__(self):
-        return (opt.name for opt in self._options.values())
-
-    def __contains__(self, name):
-        name = self._normalize_name(name)
-        return name in self._options
-
-    def __getitem__(self, name):
-        return self.__getattr__(name)
-
-    def __setitem__(self, name, value):
-        return self.__setattr__(name, value)
-
-    def items(self):
-        """A sequence of (name, value) pairs.
-
-        .. versionadded:: 3.1
-        """
-        return [(opt.name, opt.value()) for name, opt in self._options.items()]
-
-    def groups(self):
-        """The set of option-groups created by ``define``.
-
-        .. versionadded:: 3.1
-        """
-        return set(opt.group_name for opt in self._options.values())
-
-    def group_dict(self, group):
-        """The names and values of options in a group.
-
-        Useful for copying options into Application settings::
-
-            from tornado.options import define, parse_command_line, options
-
-            define('template_path', group='application')
-            define('static_path', group='application')
-
-            parse_command_line()
-
-            application = Application(
-                handlers, **options.group_dict('application'))
-
-        .. versionadded:: 3.1
-        """
-        return dict(
-            (opt.name, opt.value()) for name, opt in self._options.items()
-            if not group or group == opt.group_name)
-
-    def as_dict(self):
-        """The names and values of all options.
-
-        .. versionadded:: 3.1
-        """
-        return dict(
-            (opt.name, opt.value()) for name, opt in self._options.items())
-
-    def define(self, name, default=None, type=None, help=None, metavar=None,
-               multiple=False, group=None, callback=None):
-        """Defines a new command line option.
-
-        If ``type`` is given (one of str, float, int, datetime, or timedelta)
-        or can be inferred from the ``default``, we parse the command line
-        arguments based on the given type. If ``multiple`` is True, we accept
-        comma-separated values, and the option value is always a list.
-
-        For multi-value integers, we also accept the syntax ``x:y``, which
-        turns into ``range(x, y)`` - very useful for long integer ranges.
-
-        ``help`` and ``metavar`` are used to construct the
-        automatically generated command line help string. The help
-        message is formatted like::
-
-           --name=METAVAR      help string
-
-        ``group`` is used to group the defined options in logical
-        groups. By default, command line options are grouped by the
-        file in which they are defined.
-
-        Command line option names must be unique globally. They can be parsed
-        from the command line with `parse_command_line` or parsed from a
-        config file with `parse_config_file`.
-
-        If a ``callback`` is given, it will be run with the new value whenever
-        the option is changed.  This can be used to combine command-line
-        and file-based options::
-
-            define("config", type=str, help="path to config file",
-                   callback=lambda path: parse_config_file(path, final=False))
-
-        With this definition, options in the file specified by ``--config`` will
-        override options set earlier on the command line, but can be overridden
-        by later flags.
-        """
-        normalized = self._normalize_name(name)
-        if normalized in self._options:
-            raise Error("Option %r already defined in %s" %
-                        (normalized, self._options[normalized].file_name))
-        frame = sys._getframe(0)
-        options_file = frame.f_code.co_filename
-
-        # Can be called directly, or through top level define() fn, in which
-        # case, step up above that frame to look for real caller.
-        if (frame.f_back.f_code.co_filename == options_file and
-                frame.f_back.f_code.co_name == 'define'):
-            frame = frame.f_back
-
-        file_name = frame.f_back.f_code.co_filename
-        if file_name == options_file:
-            file_name = ""
-        if type is None:
-            if not multiple and default is not None:
-                type = default.__class__
-            else:
-                type = str
-        if group:
-            group_name = group
-        else:
-            group_name = file_name
-        option = _Option(name, file_name=file_name,
-                         default=default, type=type, help=help,
-                         metavar=metavar, multiple=multiple,
-                         group_name=group_name,
-                         callback=callback)
-        self._options[normalized] = option
-
-    def parse_command_line(self, args=None, final=True):
-        """Parses all options given on the command line (defaults to
-        `sys.argv`).
-
-        Note that ``args[0]`` is ignored since it is the program name
-        in `sys.argv`.
-
-        We return a list of all arguments that are not parsed as options.
-
-        If ``final`` is ``False``, parse callbacks will not be run.
-        This is useful for applications that wish to combine configurations
-        from multiple sources.
-        """
-        if args is None:
-            args = sys.argv
-        remaining = []
-        for i in range(1, len(args)):
-            # All things after the last option are command line arguments
-            if not args[i].startswith("-"):
-                remaining = args[i:]
-                break
-            if args[i] == "--":
-                remaining = args[i + 1:]
-                break
-            arg = args[i].lstrip("-")
-            name, equals, value = arg.partition("=")
-            name = self._normalize_name(name)
-            if name not in self._options:
-                self.print_help()
-                raise Error('Unrecognized command line option: %r' % name)
-            option = self._options[name]
-            if not equals:
-                if option.type == bool:
-                    value = "true"
-                else:
-                    raise Error('Option %r requires a value' % name)
-            option.parse(value)
-
-        if final:
-            self.run_parse_callbacks()
-
-        return remaining
-
-    def parse_config_file(self, path, final=True):
-        """Parses and loads the Python config file at the given path.
-
-        If ``final`` is ``False``, parse callbacks will not be run.
-        This is useful for applications that wish to combine configurations
-        from multiple sources.
-
-        .. versionchanged:: 4.1
-           Config files are now always interpreted as utf-8 instead of
-           the system default encoding.
-
-        .. versionchanged:: 4.4
-           The special variable ``__file__`` is available inside config
-           files, specifying the absolute path to the config file itself.
-        """
-        config = {'__file__': os.path.abspath(path)}
-        with open(path, 'rb') as f:
-            exec_in(native_str(f.read()), config, config)
-        for name in config:
-            normalized = self._normalize_name(name)
-            if normalized in self._options:
-                self._options[normalized].set(config[name])
-
-        if final:
-            self.run_parse_callbacks()
-
-    def print_help(self, file=None):
-        """Prints all the command line options to stderr (or another file)."""
-        if file is None:
-            file = sys.stderr
-        print("Usage: %s [OPTIONS]" % sys.argv[0], file=file)
-        print("\nOptions:\n", file=file)
-        by_group = {}
-        for option in self._options.values():
-            by_group.setdefault(option.group_name, []).append(option)
-
-        for filename, o in sorted(by_group.items()):
-            if filename:
-                print("\n%s options:\n" % os.path.normpath(filename), file=file)
-            o.sort(key=lambda option: option.name)
-            for option in o:
-                # Always print names with dashes in a CLI context.
-                prefix = self._normalize_name(option.name)
-                if option.metavar:
-                    prefix += "=" + option.metavar
-                description = option.help or ""
-                if option.default is not None and option.default != '':
-                    description += " (default %s)" % option.default
-                lines = textwrap.wrap(description, 79 - 35)
-                if len(prefix) > 30 or len(lines) == 0:
-                    lines.insert(0, '')
-                print("  --%-30s %s" % (prefix, lines[0]), file=file)
-                for line in lines[1:]:
-                    print("%-34s %s" % (' ', line), file=file)
-        print(file=file)
-
-    def _help_callback(self, value):
-        if value:
-            self.print_help()
-            sys.exit(0)
-
-    def add_parse_callback(self, callback):
-        """Adds a parse callback, to be invoked when option parsing is done."""
-        self._parse_callbacks.append(stack_context.wrap(callback))
-
-    def run_parse_callbacks(self):
-        for callback in self._parse_callbacks:
-            callback()
-
-    def mockable(self):
-        """Returns a wrapper around self that is compatible with
-        `mock.patch <unittest.mock.patch>`.
-
-        The `mock.patch <unittest.mock.patch>` function (included in
-        the standard library `unittest.mock` package since Python 3.3,
-        or in the third-party ``mock`` package for older versions of
-        Python) is incompatible with objects like ``options`` that
-        override ``__getattr__`` and ``__setattr__``.  This function
-        returns an object that can be used with `mock.patch.object
-        <unittest.mock.patch.object>` to modify option values::
-
-            with mock.patch.object(options.mockable(), 'name', value):
-                assert options.name == value
-        """
-        return _Mockable(self)
-
-
-class _Mockable(object):
-    """`mock.patch` compatible wrapper for `OptionParser`.
-
-    As of ``mock`` version 1.0.1, when an object uses ``__getattr__``
-    hooks instead of ``__dict__``, ``patch.__exit__`` tries to delete
-    the attribute it set instead of setting a new one (assuming that
-    the object does not catpure ``__setattr__``, so the patch
-    created a new attribute in ``__dict__``).
-
-    _Mockable's getattr and setattr pass through to the underlying
-    OptionParser, and delattr undoes the effect of a previous setattr.
-    """
-    def __init__(self, options):
-        # Modify __dict__ directly to bypass __setattr__
-        self.__dict__['_options'] = options
-        self.__dict__['_originals'] = {}
-
-    def __getattr__(self, name):
-        return getattr(self._options, name)
-
-    def __setattr__(self, name, value):
-        assert name not in self._originals, "don't reuse mockable objects"
-        self._originals[name] = getattr(self._options, name)
-        setattr(self._options, name, value)
-
-    def __delattr__(self, name):
-        setattr(self._options, name, self._originals.pop(name))
-
-
-class _Option(object):
-    UNSET = object()
-
-    def __init__(self, name, default=None, type=basestring_type, help=None,
-                 metavar=None, multiple=False, file_name=None, group_name=None,
-                 callback=None):
-        if default is None and multiple:
-            default = []
-        self.name = name
-        self.type = type
-        self.help = help
-        self.metavar = metavar
-        self.multiple = multiple
-        self.file_name = file_name
-        self.group_name = group_name
-        self.callback = callback
-        self.default = default
-        self._value = _Option.UNSET
-
-    def value(self):
-        return self.default if self._value is _Option.UNSET else self._value
-
-    def parse(self, value):
-        _parse = {
-            datetime.datetime: self._parse_datetime,
-            datetime.timedelta: self._parse_timedelta,
-            bool: self._parse_bool,
-            basestring_type: self._parse_string,
-        }.get(self.type, self.type)
-        if self.multiple:
-            self._value = []
-            for part in value.split(","):
-                if issubclass(self.type, numbers.Integral):
-                    # allow ranges of the form X:Y (inclusive at both ends)
-                    lo, _, hi = part.partition(":")
-                    lo = _parse(lo)
-                    hi = _parse(hi) if hi else lo
-                    self._value.extend(range(lo, hi + 1))
-                else:
-                    self._value.append(_parse(part))
-        else:
-            self._value = _parse(value)
-        if self.callback is not None:
-            self.callback(self._value)
-        return self.value()
-
-    def set(self, value):
-        if self.multiple:
-            if not isinstance(value, list):
-                raise Error("Option %r is required to be a list of %s" %
-                            (self.name, self.type.__name__))
-            for item in value:
-                if item is not None and not isinstance(item, self.type):
-                    raise Error("Option %r is required to be a list of %s" %
-                                (self.name, self.type.__name__))
-        else:
-            if value is not None and not isinstance(value, self.type):
-                raise Error("Option %r is required to be a %s (%s given)" %
-                            (self.name, self.type.__name__, type(value)))
-        self._value = value
-        if self.callback is not None:
-            self.callback(self._value)
-
-    # Supported date/time formats in our options
-    _DATETIME_FORMATS = [
-        "%a %b %d %H:%M:%S %Y",
-        "%Y-%m-%d %H:%M:%S",
-        "%Y-%m-%d %H:%M",
-        "%Y-%m-%dT%H:%M",
-        "%Y%m%d %H:%M:%S",
-        "%Y%m%d %H:%M",
-        "%Y-%m-%d",
-        "%Y%m%d",
-        "%H:%M:%S",
-        "%H:%M",
-    ]
-
-    def _parse_datetime(self, value):
-        for format in self._DATETIME_FORMATS:
-            try:
-                return datetime.datetime.strptime(value, format)
-            except ValueError:
-                pass
-        raise Error('Unrecognized date/time format: %r' % value)
-
-    _TIMEDELTA_ABBREV_DICT = {
-        'h': 'hours',
-        'm': 'minutes',
-        'min': 'minutes',
-        's': 'seconds',
-        'sec': 'seconds',
-        'ms': 'milliseconds',
-        'us': 'microseconds',
-        'd': 'days',
-        'w': 'weeks',
-    }
-
-    _FLOAT_PATTERN = r'[-+]?(?:\d+(?:\.\d*)?|\.\d+)(?:[eE][-+]?\d+)?'
-
-    _TIMEDELTA_PATTERN = re.compile(
-        r'\s*(%s)\s*(\w*)\s*' % _FLOAT_PATTERN, re.IGNORECASE)
-
-    def _parse_timedelta(self, value):
-        try:
-            sum = datetime.timedelta()
-            start = 0
-            while start < len(value):
-                m = self._TIMEDELTA_PATTERN.match(value, start)
-                if not m:
-                    raise Exception()
-                num = float(m.group(1))
-                units = m.group(2) or 'seconds'
-                units = self._TIMEDELTA_ABBREV_DICT.get(units, units)
-                sum += datetime.timedelta(**{units: num})
-                start = m.end()
-            return sum
-        except Exception:
-            raise
-
-    def _parse_bool(self, value):
-        return value.lower() not in ("false", "0", "f")
-
-    def _parse_string(self, value):
-        return _unicode(value)
-
-
-options = OptionParser()
-"""Global options object.
-
-All defined options are available as attributes on this object.
-"""
-
-
-def define(name, default=None, type=None, help=None, metavar=None,
-           multiple=False, group=None, callback=None):
-    """Defines an option in the global namespace.
-
-    See `OptionParser.define`.
-    """
-    return options.define(name, default=default, type=type, help=help,
-                          metavar=metavar, multiple=multiple, group=group,
-                          callback=callback)
-
-
-def parse_command_line(args=None, final=True):
-    """Parses global options from the command line.
-
-    See `OptionParser.parse_command_line`.
-    """
-    return options.parse_command_line(args, final=final)
-
-
-def parse_config_file(path, final=True):
-    """Parses global options from a config file.
-
-    See `OptionParser.parse_config_file`.
-    """
-    return options.parse_config_file(path, final=final)
-
-
-def print_help(file=None):
-    """Prints all the command line options to stderr (or another file).
-
-    See `OptionParser.print_help`.
-    """
-    return options.print_help(file)
-
-
-def add_parse_callback(callback):
-    """Adds a parse callback, to be invoked when option parsing is done.
-
-    See `OptionParser.add_parse_callback`
-    """
-    options.add_parse_callback(callback)
-
-
-# Default options
-define_logging_options(options)
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""A command line parsing module that lets modules define their own options. 
+ 
+Each module defines its own options which are added to the global 
+option namespace, e.g.:: 
+ 
+    from tornado.options import define, options 
+ 
+    define("mysql_host", default="127.0.0.1:3306", help="Main user DB") 
+    define("memcache_hosts", default="127.0.0.1:11011", multiple=True, 
+           help="Main user memcache servers") 
+ 
+    def connect(): 
+        db = database.Connection(options.mysql_host) 
+        ... 
+ 
+The ``main()`` method of your application does not need to be aware of all of 
+the options used throughout your program; they are all automatically loaded 
+when the modules are loaded.  However, all modules that define options 
+must have been imported before the command line is parsed. 
+ 
+Your ``main()`` method can parse the command line or parse a config file with 
+either:: 
+ 
+    tornado.options.parse_command_line() 
+    # or 
+    tornado.options.parse_config_file("/etc/server.conf") 
+ 
+.. note: 
+ 
+   When using tornado.options.parse_command_line or 
+   tornado.options.parse_config_file, the only options that are set are 
+   ones that were previously defined with tornado.options.define. 
+ 
+Command line formats are what you would expect (``--myoption=myvalue``). 
+Config files are just Python files. Global names become options, e.g.:: 
+ 
+    myoption = "myvalue" 
+    myotheroption = "myothervalue" 
+ 
+We support `datetimes <datetime.datetime>`, `timedeltas 
+<datetime.timedelta>`, ints, and floats (just pass a ``type`` kwarg to 
+`define`). We also accept multi-value options. See the documentation for 
+`define()` below. 
+ 
+`tornado.options.options` is a singleton instance of `OptionParser`, and 
+the top-level functions in this module (`define`, `parse_command_line`, etc) 
+simply call methods on it.  You may create additional `OptionParser` 
+instances to define isolated sets of options, such as for subcommands. 
+ 
+.. note:: 
+ 
+   By default, several options are defined that will configure the 
+   standard `logging` module when `parse_command_line` or `parse_config_file` 
+   are called.  If you want Tornado to leave the logging configuration 
+   alone so you can manage it yourself, either pass ``--logging=none`` 
+   on the command line or do the following to disable it in code:: 
+ 
+       from tornado.options import options, parse_command_line 
+       options.logging = None 
+       parse_command_line() 
+ 
+.. versionchanged:: 4.3 
+   Dashes and underscores are fully interchangeable in option names; 
+   options can be defined, set, and read with any mix of the two. 
+   Dashes are typical for command-line usage while config files require 
+   underscores. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import datetime 
+import numbers 
+import re 
+import sys 
+import os 
+import textwrap 
+ 
+from tornado.escape import _unicode, native_str 
+from tornado.log import define_logging_options 
+from tornado import stack_context 
+from tornado.util import basestring_type, exec_in 
+ 
+ 
+class Error(Exception): 
+    """Exception raised by errors in the options module.""" 
+    pass 
+ 
+ 
+class OptionParser(object): 
+    """A collection of options, a dictionary with object-like access. 
+ 
+    Normally accessed via static functions in the `tornado.options` module, 
+    which reference a global instance. 
+    """ 
+    def __init__(self): 
+        # we have to use self.__dict__ because we override setattr. 
+        self.__dict__['_options'] = {} 
+        self.__dict__['_parse_callbacks'] = [] 
+        self.define("help", type=bool, help="show this help information", 
+                    callback=self._help_callback) 
+ 
+    def _normalize_name(self, name): 
+        return name.replace('_', '-') 
+ 
+    def __getattr__(self, name): 
+        name = self._normalize_name(name) 
+        if isinstance(self._options.get(name), _Option): 
+            return self._options[name].value() 
+        raise AttributeError("Unrecognized option %r" % name) 
+ 
+    def __setattr__(self, name, value): 
+        name = self._normalize_name(name) 
+        if isinstance(self._options.get(name), _Option): 
+            return self._options[name].set(value) 
+        raise AttributeError("Unrecognized option %r" % name) 
+ 
+    def __iter__(self): 
+        return (opt.name for opt in self._options.values()) 
+ 
+    def __contains__(self, name): 
+        name = self._normalize_name(name) 
+        return name in self._options 
+ 
+    def __getitem__(self, name): 
+        return self.__getattr__(name) 
+ 
+    def __setitem__(self, name, value): 
+        return self.__setattr__(name, value) 
+ 
+    def items(self): 
+        """A sequence of (name, value) pairs. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        return [(opt.name, opt.value()) for name, opt in self._options.items()] 
+ 
+    def groups(self): 
+        """The set of option-groups created by ``define``. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        return set(opt.group_name for opt in self._options.values()) 
+ 
+    def group_dict(self, group): 
+        """The names and values of options in a group. 
+ 
+        Useful for copying options into Application settings:: 
+ 
+            from tornado.options import define, parse_command_line, options 
+ 
+            define('template_path', group='application') 
+            define('static_path', group='application') 
+ 
+            parse_command_line() 
+ 
+            application = Application( 
+                handlers, **options.group_dict('application')) 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        return dict( 
+            (opt.name, opt.value()) for name, opt in self._options.items() 
+            if not group or group == opt.group_name) 
+ 
+    def as_dict(self): 
+        """The names and values of all options. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        return dict( 
+            (opt.name, opt.value()) for name, opt in self._options.items()) 
+ 
+    def define(self, name, default=None, type=None, help=None, metavar=None, 
+               multiple=False, group=None, callback=None): 
+        """Defines a new command line option. 
+ 
+        If ``type`` is given (one of str, float, int, datetime, or timedelta) 
+        or can be inferred from the ``default``, we parse the command line 
+        arguments based on the given type. If ``multiple`` is True, we accept 
+        comma-separated values, and the option value is always a list. 
+ 
+        For multi-value integers, we also accept the syntax ``x:y``, which 
+        turns into ``range(x, y)`` - very useful for long integer ranges. 
+ 
+        ``help`` and ``metavar`` are used to construct the 
+        automatically generated command line help string. The help 
+        message is formatted like:: 
+ 
+           --name=METAVAR      help string 
+ 
+        ``group`` is used to group the defined options in logical 
+        groups. By default, command line options are grouped by the 
+        file in which they are defined. 
+ 
+        Command line option names must be unique globally. They can be parsed 
+        from the command line with `parse_command_line` or parsed from a 
+        config file with `parse_config_file`. 
+ 
+        If a ``callback`` is given, it will be run with the new value whenever 
+        the option is changed.  This can be used to combine command-line 
+        and file-based options:: 
+ 
+            define("config", type=str, help="path to config file", 
+                   callback=lambda path: parse_config_file(path, final=False)) 
+ 
+        With this definition, options in the file specified by ``--config`` will 
+        override options set earlier on the command line, but can be overridden 
+        by later flags. 
+        """ 
+        normalized = self._normalize_name(name) 
+        if normalized in self._options: 
+            raise Error("Option %r already defined in %s" % 
+                        (normalized, self._options[normalized].file_name)) 
+        frame = sys._getframe(0) 
+        options_file = frame.f_code.co_filename 
+ 
+        # Can be called directly, or through top level define() fn, in which 
+        # case, step up above that frame to look for real caller. 
+        if (frame.f_back.f_code.co_filename == options_file and 
+                frame.f_back.f_code.co_name == 'define'): 
+            frame = frame.f_back 
+ 
+        file_name = frame.f_back.f_code.co_filename 
+        if file_name == options_file: 
+            file_name = "" 
+        if type is None: 
+            if not multiple and default is not None: 
+                type = default.__class__ 
+            else: 
+                type = str 
+        if group: 
+            group_name = group 
+        else: 
+            group_name = file_name 
+        option = _Option(name, file_name=file_name, 
+                         default=default, type=type, help=help, 
+                         metavar=metavar, multiple=multiple, 
+                         group_name=group_name, 
+                         callback=callback) 
+        self._options[normalized] = option 
+ 
+    def parse_command_line(self, args=None, final=True): 
+        """Parses all options given on the command line (defaults to 
+        `sys.argv`). 
+ 
+        Note that ``args[0]`` is ignored since it is the program name 
+        in `sys.argv`. 
+ 
+        We return a list of all arguments that are not parsed as options. 
+ 
+        If ``final`` is ``False``, parse callbacks will not be run. 
+        This is useful for applications that wish to combine configurations 
+        from multiple sources. 
+        """ 
+        if args is None: 
+            args = sys.argv 
+        remaining = [] 
+        for i in range(1, len(args)): 
+            # All things after the last option are command line arguments 
+            if not args[i].startswith("-"): 
+                remaining = args[i:] 
+                break 
+            if args[i] == "--": 
+                remaining = args[i + 1:] 
+                break 
+            arg = args[i].lstrip("-") 
+            name, equals, value = arg.partition("=") 
+            name = self._normalize_name(name) 
+            if name not in self._options: 
+                self.print_help() 
+                raise Error('Unrecognized command line option: %r' % name) 
+            option = self._options[name] 
+            if not equals: 
+                if option.type == bool: 
+                    value = "true" 
+                else: 
+                    raise Error('Option %r requires a value' % name) 
+            option.parse(value) 
+ 
+        if final: 
+            self.run_parse_callbacks() 
+ 
+        return remaining 
+ 
+    def parse_config_file(self, path, final=True): 
+        """Parses and loads the Python config file at the given path. 
+ 
+        If ``final`` is ``False``, parse callbacks will not be run. 
+        This is useful for applications that wish to combine configurations 
+        from multiple sources. 
+ 
+        .. versionchanged:: 4.1 
+           Config files are now always interpreted as utf-8 instead of 
+           the system default encoding. 
+ 
+        .. versionchanged:: 4.4 
+           The special variable ``__file__`` is available inside config 
+           files, specifying the absolute path to the config file itself. 
+        """ 
+        config = {'__file__': os.path.abspath(path)} 
+        with open(path, 'rb') as f: 
+            exec_in(native_str(f.read()), config, config) 
+        for name in config: 
+            normalized = self._normalize_name(name) 
+            if normalized in self._options: 
+                self._options[normalized].set(config[name]) 
+ 
+        if final: 
+            self.run_parse_callbacks() 
+ 
+    def print_help(self, file=None): 
+        """Prints all the command line options to stderr (or another file).""" 
+        if file is None: 
+            file = sys.stderr 
+        print("Usage: %s [OPTIONS]" % sys.argv[0], file=file) 
+        print("\nOptions:\n", file=file) 
+        by_group = {} 
+        for option in self._options.values(): 
+            by_group.setdefault(option.group_name, []).append(option) 
+ 
+        for filename, o in sorted(by_group.items()): 
+            if filename: 
+                print("\n%s options:\n" % os.path.normpath(filename), file=file) 
+            o.sort(key=lambda option: option.name) 
+            for option in o: 
+                # Always print names with dashes in a CLI context. 
+                prefix = self._normalize_name(option.name) 
+                if option.metavar: 
+                    prefix += "=" + option.metavar 
+                description = option.help or "" 
+                if option.default is not None and option.default != '': 
+                    description += " (default %s)" % option.default 
+                lines = textwrap.wrap(description, 79 - 35) 
+                if len(prefix) > 30 or len(lines) == 0: 
+                    lines.insert(0, '') 
+                print("  --%-30s %s" % (prefix, lines[0]), file=file) 
+                for line in lines[1:]: 
+                    print("%-34s %s" % (' ', line), file=file) 
+        print(file=file) 
+ 
+    def _help_callback(self, value): 
+        if value: 
+            self.print_help() 
+            sys.exit(0) 
+ 
+    def add_parse_callback(self, callback): 
+        """Adds a parse callback, to be invoked when option parsing is done.""" 
+        self._parse_callbacks.append(stack_context.wrap(callback)) 
+ 
+    def run_parse_callbacks(self): 
+        for callback in self._parse_callbacks: 
+            callback() 
+ 
+    def mockable(self): 
+        """Returns a wrapper around self that is compatible with 
+        `mock.patch <unittest.mock.patch>`. 
+ 
+        The `mock.patch <unittest.mock.patch>` function (included in 
+        the standard library `unittest.mock` package since Python 3.3, 
+        or in the third-party ``mock`` package for older versions of 
+        Python) is incompatible with objects like ``options`` that 
+        override ``__getattr__`` and ``__setattr__``.  This function 
+        returns an object that can be used with `mock.patch.object 
+        <unittest.mock.patch.object>` to modify option values:: 
+ 
+            with mock.patch.object(options.mockable(), 'name', value): 
+                assert options.name == value 
+        """ 
+        return _Mockable(self) 
+ 
+ 
+class _Mockable(object): 
+    """`mock.patch` compatible wrapper for `OptionParser`. 
+ 
+    As of ``mock`` version 1.0.1, when an object uses ``__getattr__`` 
+    hooks instead of ``__dict__``, ``patch.__exit__`` tries to delete 
+    the attribute it set instead of setting a new one (assuming that 
+    the object does not catpure ``__setattr__``, so the patch 
+    created a new attribute in ``__dict__``). 
+ 
+    _Mockable's getattr and setattr pass through to the underlying 
+    OptionParser, and delattr undoes the effect of a previous setattr. 
+    """ 
+    def __init__(self, options): 
+        # Modify __dict__ directly to bypass __setattr__ 
+        self.__dict__['_options'] = options 
+        self.__dict__['_originals'] = {} 
+ 
+    def __getattr__(self, name): 
+        return getattr(self._options, name) 
+ 
+    def __setattr__(self, name, value): 
+        assert name not in self._originals, "don't reuse mockable objects" 
+        self._originals[name] = getattr(self._options, name) 
+        setattr(self._options, name, value) 
+ 
+    def __delattr__(self, name): 
+        setattr(self._options, name, self._originals.pop(name)) 
+ 
+ 
+class _Option(object): 
+    UNSET = object() 
+ 
+    def __init__(self, name, default=None, type=basestring_type, help=None, 
+                 metavar=None, multiple=False, file_name=None, group_name=None, 
+                 callback=None): 
+        if default is None and multiple: 
+            default = [] 
+        self.name = name 
+        self.type = type 
+        self.help = help 
+        self.metavar = metavar 
+        self.multiple = multiple 
+        self.file_name = file_name 
+        self.group_name = group_name 
+        self.callback = callback 
+        self.default = default 
+        self._value = _Option.UNSET 
+ 
+    def value(self): 
+        return self.default if self._value is _Option.UNSET else self._value 
+ 
+    def parse(self, value): 
+        _parse = { 
+            datetime.datetime: self._parse_datetime, 
+            datetime.timedelta: self._parse_timedelta, 
+            bool: self._parse_bool, 
+            basestring_type: self._parse_string, 
+        }.get(self.type, self.type) 
+        if self.multiple: 
+            self._value = [] 
+            for part in value.split(","): 
+                if issubclass(self.type, numbers.Integral): 
+                    # allow ranges of the form X:Y (inclusive at both ends) 
+                    lo, _, hi = part.partition(":") 
+                    lo = _parse(lo) 
+                    hi = _parse(hi) if hi else lo 
+                    self._value.extend(range(lo, hi + 1)) 
+                else: 
+                    self._value.append(_parse(part)) 
+        else: 
+            self._value = _parse(value) 
+        if self.callback is not None: 
+            self.callback(self._value) 
+        return self.value() 
+ 
+    def set(self, value): 
+        if self.multiple: 
+            if not isinstance(value, list): 
+                raise Error("Option %r is required to be a list of %s" % 
+                            (self.name, self.type.__name__)) 
+            for item in value: 
+                if item is not None and not isinstance(item, self.type): 
+                    raise Error("Option %r is required to be a list of %s" % 
+                                (self.name, self.type.__name__)) 
+        else: 
+            if value is not None and not isinstance(value, self.type): 
+                raise Error("Option %r is required to be a %s (%s given)" % 
+                            (self.name, self.type.__name__, type(value))) 
+        self._value = value 
+        if self.callback is not None: 
+            self.callback(self._value) 
+ 
+    # Supported date/time formats in our options 
+    _DATETIME_FORMATS = [ 
+        "%a %b %d %H:%M:%S %Y", 
+        "%Y-%m-%d %H:%M:%S", 
+        "%Y-%m-%d %H:%M", 
+        "%Y-%m-%dT%H:%M", 
+        "%Y%m%d %H:%M:%S", 
+        "%Y%m%d %H:%M", 
+        "%Y-%m-%d", 
+        "%Y%m%d", 
+        "%H:%M:%S", 
+        "%H:%M", 
+    ] 
+ 
+    def _parse_datetime(self, value): 
+        for format in self._DATETIME_FORMATS: 
+            try: 
+                return datetime.datetime.strptime(value, format) 
+            except ValueError: 
+                pass 
+        raise Error('Unrecognized date/time format: %r' % value) 
+ 
+    _TIMEDELTA_ABBREV_DICT = { 
+        'h': 'hours', 
+        'm': 'minutes', 
+        'min': 'minutes', 
+        's': 'seconds', 
+        'sec': 'seconds', 
+        'ms': 'milliseconds', 
+        'us': 'microseconds', 
+        'd': 'days', 
+        'w': 'weeks', 
+    } 
+ 
+    _FLOAT_PATTERN = r'[-+]?(?:\d+(?:\.\d*)?|\.\d+)(?:[eE][-+]?\d+)?' 
+ 
+    _TIMEDELTA_PATTERN = re.compile( 
+        r'\s*(%s)\s*(\w*)\s*' % _FLOAT_PATTERN, re.IGNORECASE) 
+ 
+    def _parse_timedelta(self, value): 
+        try: 
+            sum = datetime.timedelta() 
+            start = 0 
+            while start < len(value): 
+                m = self._TIMEDELTA_PATTERN.match(value, start) 
+                if not m: 
+                    raise Exception() 
+                num = float(m.group(1)) 
+                units = m.group(2) or 'seconds' 
+                units = self._TIMEDELTA_ABBREV_DICT.get(units, units) 
+                sum += datetime.timedelta(**{units: num}) 
+                start = m.end() 
+            return sum 
+        except Exception: 
+            raise 
+ 
+    def _parse_bool(self, value): 
+        return value.lower() not in ("false", "0", "f") 
+ 
+    def _parse_string(self, value): 
+        return _unicode(value) 
+ 
+ 
+options = OptionParser() 
+"""Global options object. 
+ 
+All defined options are available as attributes on this object. 
+""" 
+ 
+ 
+def define(name, default=None, type=None, help=None, metavar=None, 
+           multiple=False, group=None, callback=None): 
+    """Defines an option in the global namespace. 
+ 
+    See `OptionParser.define`. 
+    """ 
+    return options.define(name, default=default, type=type, help=help, 
+                          metavar=metavar, multiple=multiple, group=group, 
+                          callback=callback) 
+ 
+ 
+def parse_command_line(args=None, final=True): 
+    """Parses global options from the command line. 
+ 
+    See `OptionParser.parse_command_line`. 
+    """ 
+    return options.parse_command_line(args, final=final) 
+ 
+ 
+def parse_config_file(path, final=True): 
+    """Parses global options from a config file. 
+ 
+    See `OptionParser.parse_config_file`. 
+    """ 
+    return options.parse_config_file(path, final=final) 
+ 
+ 
+def print_help(file=None): 
+    """Prints all the command line options to stderr (or another file). 
+ 
+    See `OptionParser.print_help`. 
+    """ 
+    return options.print_help(file) 
+ 
+ 
+def add_parse_callback(callback): 
+    """Adds a parse callback, to be invoked when option parsing is done. 
+ 
+    See `OptionParser.add_parse_callback` 
+    """ 
+    options.add_parse_callback(callback) 
+ 
+ 
+# Default options 
+define_logging_options(options) 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/asyncio.py b/contrib/python/tornado/tornado-4/tornado/platform/asyncio.py
index 830ee1f3b1..e30277225f 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/asyncio.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/asyncio.py
@@ -1,222 +1,222 @@
-"""Bridges between the `asyncio` module and Tornado IOLoop.
-
-.. versionadded:: 3.2
-
-This module integrates Tornado with the ``asyncio`` module introduced
-in Python 3.4 (and available `as a separate download
-<https://pypi.python.org/pypi/asyncio>`_ for Python 3.3).  This makes
-it possible to combine the two libraries on the same event loop.
-
-Most applications should use `AsyncIOMainLoop` to run Tornado on the
-default ``asyncio`` event loop.  Applications that need to run event
-loops on multiple threads may use `AsyncIOLoop` to create multiple
-loops.
-
-.. note::
-
-   Tornado requires the `~asyncio.AbstractEventLoop.add_reader` family of
-   methods, so it is not compatible with the `~asyncio.ProactorEventLoop` on
-   Windows. Use the `~asyncio.SelectorEventLoop` instead.
-"""
-
-from __future__ import absolute_import, division, print_function
-import functools
-
-import tornado.concurrent
-from tornado.gen import convert_yielded
-from tornado.ioloop import IOLoop
-from tornado import stack_context
-
-try:
-    # Import the real asyncio module for py33+ first.  Older versions of the
-    # trollius backport also use this name.
-    import asyncio  # type: ignore
-except ImportError as e:
-    # Asyncio itself isn't available; see if trollius is (backport to py26+).
-    try:
-        import trollius as asyncio  # type: ignore
-    except ImportError:
-        # Re-raise the original asyncio error, not the trollius one.
-        raise e
-
-
-class BaseAsyncIOLoop(IOLoop):
-    def initialize(self, asyncio_loop, close_loop=False, **kwargs):
-        super(BaseAsyncIOLoop, self).initialize(**kwargs)
-        self.asyncio_loop = asyncio_loop
-        self.close_loop = close_loop
-        # Maps fd to (fileobj, handler function) pair (as in IOLoop.add_handler)
-        self.handlers = {}
-        # Set of fds listening for reads/writes
-        self.readers = set()
-        self.writers = set()
-        self.closing = False
-
-    def close(self, all_fds=False):
-        self.closing = True
-        for fd in list(self.handlers):
-            fileobj, handler_func = self.handlers[fd]
-            self.remove_handler(fd)
-            if all_fds:
-                self.close_fd(fileobj)
-        if self.close_loop:
-            self.asyncio_loop.close()
-
-    def add_handler(self, fd, handler, events):
-        fd, fileobj = self.split_fd(fd)
-        if fd in self.handlers:
-            raise ValueError("fd %s added twice" % fd)
-        self.handlers[fd] = (fileobj, stack_context.wrap(handler))
-        if events & IOLoop.READ:
-            self.asyncio_loop.add_reader(
-                fd, self._handle_events, fd, IOLoop.READ)
-            self.readers.add(fd)
-        if events & IOLoop.WRITE:
-            self.asyncio_loop.add_writer(
-                fd, self._handle_events, fd, IOLoop.WRITE)
-            self.writers.add(fd)
-
-    def update_handler(self, fd, events):
-        fd, fileobj = self.split_fd(fd)
-        if events & IOLoop.READ:
-            if fd not in self.readers:
-                self.asyncio_loop.add_reader(
-                    fd, self._handle_events, fd, IOLoop.READ)
-                self.readers.add(fd)
-        else:
-            if fd in self.readers:
-                self.asyncio_loop.remove_reader(fd)
-                self.readers.remove(fd)
-        if events & IOLoop.WRITE:
-            if fd not in self.writers:
-                self.asyncio_loop.add_writer(
-                    fd, self._handle_events, fd, IOLoop.WRITE)
-                self.writers.add(fd)
-        else:
-            if fd in self.writers:
-                self.asyncio_loop.remove_writer(fd)
-                self.writers.remove(fd)
-
-    def remove_handler(self, fd):
-        fd, fileobj = self.split_fd(fd)
-        if fd not in self.handlers:
-            return
-        if fd in self.readers:
-            self.asyncio_loop.remove_reader(fd)
-            self.readers.remove(fd)
-        if fd in self.writers:
-            self.asyncio_loop.remove_writer(fd)
-            self.writers.remove(fd)
-        del self.handlers[fd]
-
-    def _handle_events(self, fd, events):
-        fileobj, handler_func = self.handlers[fd]
-        handler_func(fileobj, events)
-
-    def start(self):
-        old_current = IOLoop.current(instance=False)
-        try:
-            self._setup_logging()
-            self.make_current()
-            self.asyncio_loop.run_forever()
-        finally:
-            if old_current is None:
-                IOLoop.clear_current()
-            else:
-                old_current.make_current()
-
-    def stop(self):
-        self.asyncio_loop.stop()
-
-    def call_at(self, when, callback, *args, **kwargs):
-        # asyncio.call_at supports *args but not **kwargs, so bind them here.
-        # We do not synchronize self.time and asyncio_loop.time, so
-        # convert from absolute to relative.
-        return self.asyncio_loop.call_later(
-            max(0, when - self.time()), self._run_callback,
-            functools.partial(stack_context.wrap(callback), *args, **kwargs))
-
-    def remove_timeout(self, timeout):
-        timeout.cancel()
-
-    def add_callback(self, callback, *args, **kwargs):
-        if self.closing:
-            # TODO: this is racy; we need a lock to ensure that the
-            # loop isn't closed during call_soon_threadsafe.
-            raise RuntimeError("IOLoop is closing")
-        self.asyncio_loop.call_soon_threadsafe(
-            self._run_callback,
-            functools.partial(stack_context.wrap(callback), *args, **kwargs))
-
-    add_callback_from_signal = add_callback
-
-
-class AsyncIOMainLoop(BaseAsyncIOLoop):
-    """``AsyncIOMainLoop`` creates an `.IOLoop` that corresponds to the
-    current ``asyncio`` event loop (i.e. the one returned by
-    ``asyncio.get_event_loop()``).  Recommended usage::
-
-        from tornado.platform.asyncio import AsyncIOMainLoop
-        import asyncio
-        AsyncIOMainLoop().install()
-        asyncio.get_event_loop().run_forever()
-
-    See also :meth:`tornado.ioloop.IOLoop.install` for general notes on
-    installing alternative IOLoops.
-    """
-    def initialize(self, **kwargs):
-        super(AsyncIOMainLoop, self).initialize(asyncio.get_event_loop(),
-                                                close_loop=False, **kwargs)
-
-
-class AsyncIOLoop(BaseAsyncIOLoop):
-    """``AsyncIOLoop`` is an `.IOLoop` that runs on an ``asyncio`` event loop.
-    This class follows the usual Tornado semantics for creating new
-    ``IOLoops``; these loops are not necessarily related to the
-    ``asyncio`` default event loop.  Recommended usage::
-
-        from tornado.ioloop import IOLoop
-        IOLoop.configure('tornado.platform.asyncio.AsyncIOLoop')
-        IOLoop.current().start()
-
-    Each ``AsyncIOLoop`` creates a new ``asyncio.EventLoop``; this object
-    can be accessed with the ``asyncio_loop`` attribute.
-    """
-    def initialize(self, **kwargs):
-        loop = asyncio.new_event_loop()
-        try:
-            super(AsyncIOLoop, self).initialize(loop, close_loop=True, **kwargs)
-        except Exception:
-            # If initialize() does not succeed (taking ownership of the loop),
-            # we have to close it.
-            loop.close()
-            raise
-
-
-def to_tornado_future(asyncio_future):
-    """Convert an `asyncio.Future` to a `tornado.concurrent.Future`.
-
-    .. versionadded:: 4.1
-    """
-    tf = tornado.concurrent.Future()
-    tornado.concurrent.chain_future(asyncio_future, tf)
-    return tf
-
-
-def to_asyncio_future(tornado_future):
-    """Convert a Tornado yieldable object to an `asyncio.Future`.
-
-    .. versionadded:: 4.1
-
-    .. versionchanged:: 4.3
-       Now accepts any yieldable object, not just
-       `tornado.concurrent.Future`.
-    """
-    tornado_future = convert_yielded(tornado_future)
-    af = asyncio.Future()
-    tornado.concurrent.chain_future(tornado_future, af)
-    return af
-
-
-if hasattr(convert_yielded, 'register'):
-    convert_yielded.register(asyncio.Future, to_tornado_future)  # type: ignore
+"""Bridges between the `asyncio` module and Tornado IOLoop. 
+ 
+.. versionadded:: 3.2 
+ 
+This module integrates Tornado with the ``asyncio`` module introduced 
+in Python 3.4 (and available `as a separate download 
+<https://pypi.python.org/pypi/asyncio>`_ for Python 3.3).  This makes 
+it possible to combine the two libraries on the same event loop. 
+ 
+Most applications should use `AsyncIOMainLoop` to run Tornado on the 
+default ``asyncio`` event loop.  Applications that need to run event 
+loops on multiple threads may use `AsyncIOLoop` to create multiple 
+loops. 
+ 
+.. note:: 
+ 
+   Tornado requires the `~asyncio.AbstractEventLoop.add_reader` family of 
+   methods, so it is not compatible with the `~asyncio.ProactorEventLoop` on 
+   Windows. Use the `~asyncio.SelectorEventLoop` instead. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+import functools 
+ 
+import tornado.concurrent 
+from tornado.gen import convert_yielded 
+from tornado.ioloop import IOLoop 
+from tornado import stack_context 
+ 
+try: 
+    # Import the real asyncio module for py33+ first.  Older versions of the 
+    # trollius backport also use this name. 
+    import asyncio  # type: ignore 
+except ImportError as e: 
+    # Asyncio itself isn't available; see if trollius is (backport to py26+). 
+    try: 
+        import trollius as asyncio  # type: ignore 
+    except ImportError: 
+        # Re-raise the original asyncio error, not the trollius one. 
+        raise e 
+ 
+ 
+class BaseAsyncIOLoop(IOLoop): 
+    def initialize(self, asyncio_loop, close_loop=False, **kwargs): 
+        super(BaseAsyncIOLoop, self).initialize(**kwargs) 
+        self.asyncio_loop = asyncio_loop 
+        self.close_loop = close_loop 
+        # Maps fd to (fileobj, handler function) pair (as in IOLoop.add_handler) 
+        self.handlers = {} 
+        # Set of fds listening for reads/writes 
+        self.readers = set() 
+        self.writers = set() 
+        self.closing = False 
+ 
+    def close(self, all_fds=False): 
+        self.closing = True 
+        for fd in list(self.handlers): 
+            fileobj, handler_func = self.handlers[fd] 
+            self.remove_handler(fd) 
+            if all_fds: 
+                self.close_fd(fileobj) 
+        if self.close_loop: 
+            self.asyncio_loop.close() 
+ 
+    def add_handler(self, fd, handler, events): 
+        fd, fileobj = self.split_fd(fd) 
+        if fd in self.handlers: 
+            raise ValueError("fd %s added twice" % fd) 
+        self.handlers[fd] = (fileobj, stack_context.wrap(handler)) 
+        if events & IOLoop.READ: 
+            self.asyncio_loop.add_reader( 
+                fd, self._handle_events, fd, IOLoop.READ) 
+            self.readers.add(fd) 
+        if events & IOLoop.WRITE: 
+            self.asyncio_loop.add_writer( 
+                fd, self._handle_events, fd, IOLoop.WRITE) 
+            self.writers.add(fd) 
+ 
+    def update_handler(self, fd, events): 
+        fd, fileobj = self.split_fd(fd) 
+        if events & IOLoop.READ: 
+            if fd not in self.readers: 
+                self.asyncio_loop.add_reader( 
+                    fd, self._handle_events, fd, IOLoop.READ) 
+                self.readers.add(fd) 
+        else: 
+            if fd in self.readers: 
+                self.asyncio_loop.remove_reader(fd) 
+                self.readers.remove(fd) 
+        if events & IOLoop.WRITE: 
+            if fd not in self.writers: 
+                self.asyncio_loop.add_writer( 
+                    fd, self._handle_events, fd, IOLoop.WRITE) 
+                self.writers.add(fd) 
+        else: 
+            if fd in self.writers: 
+                self.asyncio_loop.remove_writer(fd) 
+                self.writers.remove(fd) 
+ 
+    def remove_handler(self, fd): 
+        fd, fileobj = self.split_fd(fd) 
+        if fd not in self.handlers: 
+            return 
+        if fd in self.readers: 
+            self.asyncio_loop.remove_reader(fd) 
+            self.readers.remove(fd) 
+        if fd in self.writers: 
+            self.asyncio_loop.remove_writer(fd) 
+            self.writers.remove(fd) 
+        del self.handlers[fd] 
+ 
+    def _handle_events(self, fd, events): 
+        fileobj, handler_func = self.handlers[fd] 
+        handler_func(fileobj, events) 
+ 
+    def start(self): 
+        old_current = IOLoop.current(instance=False) 
+        try: 
+            self._setup_logging() 
+            self.make_current() 
+            self.asyncio_loop.run_forever() 
+        finally: 
+            if old_current is None: 
+                IOLoop.clear_current() 
+            else: 
+                old_current.make_current() 
+ 
+    def stop(self): 
+        self.asyncio_loop.stop() 
+ 
+    def call_at(self, when, callback, *args, **kwargs): 
+        # asyncio.call_at supports *args but not **kwargs, so bind them here. 
+        # We do not synchronize self.time and asyncio_loop.time, so 
+        # convert from absolute to relative. 
+        return self.asyncio_loop.call_later( 
+            max(0, when - self.time()), self._run_callback, 
+            functools.partial(stack_context.wrap(callback), *args, **kwargs)) 
+ 
+    def remove_timeout(self, timeout): 
+        timeout.cancel() 
+ 
+    def add_callback(self, callback, *args, **kwargs): 
+        if self.closing: 
+            # TODO: this is racy; we need a lock to ensure that the 
+            # loop isn't closed during call_soon_threadsafe. 
+            raise RuntimeError("IOLoop is closing") 
+        self.asyncio_loop.call_soon_threadsafe( 
+            self._run_callback, 
+            functools.partial(stack_context.wrap(callback), *args, **kwargs)) 
+ 
+    add_callback_from_signal = add_callback 
+ 
+ 
+class AsyncIOMainLoop(BaseAsyncIOLoop): 
+    """``AsyncIOMainLoop`` creates an `.IOLoop` that corresponds to the 
+    current ``asyncio`` event loop (i.e. the one returned by 
+    ``asyncio.get_event_loop()``).  Recommended usage:: 
+ 
+        from tornado.platform.asyncio import AsyncIOMainLoop 
+        import asyncio 
+        AsyncIOMainLoop().install() 
+        asyncio.get_event_loop().run_forever() 
+ 
+    See also :meth:`tornado.ioloop.IOLoop.install` for general notes on 
+    installing alternative IOLoops. 
+    """ 
+    def initialize(self, **kwargs): 
+        super(AsyncIOMainLoop, self).initialize(asyncio.get_event_loop(), 
+                                                close_loop=False, **kwargs) 
+ 
+ 
+class AsyncIOLoop(BaseAsyncIOLoop): 
+    """``AsyncIOLoop`` is an `.IOLoop` that runs on an ``asyncio`` event loop. 
+    This class follows the usual Tornado semantics for creating new 
+    ``IOLoops``; these loops are not necessarily related to the 
+    ``asyncio`` default event loop.  Recommended usage:: 
+ 
+        from tornado.ioloop import IOLoop 
+        IOLoop.configure('tornado.platform.asyncio.AsyncIOLoop') 
+        IOLoop.current().start() 
+ 
+    Each ``AsyncIOLoop`` creates a new ``asyncio.EventLoop``; this object 
+    can be accessed with the ``asyncio_loop`` attribute. 
+    """ 
+    def initialize(self, **kwargs): 
+        loop = asyncio.new_event_loop() 
+        try: 
+            super(AsyncIOLoop, self).initialize(loop, close_loop=True, **kwargs) 
+        except Exception: 
+            # If initialize() does not succeed (taking ownership of the loop), 
+            # we have to close it. 
+            loop.close() 
+            raise 
+ 
+ 
+def to_tornado_future(asyncio_future): 
+    """Convert an `asyncio.Future` to a `tornado.concurrent.Future`. 
+ 
+    .. versionadded:: 4.1 
+    """ 
+    tf = tornado.concurrent.Future() 
+    tornado.concurrent.chain_future(asyncio_future, tf) 
+    return tf 
+ 
+ 
+def to_asyncio_future(tornado_future): 
+    """Convert a Tornado yieldable object to an `asyncio.Future`. 
+ 
+    .. versionadded:: 4.1 
+ 
+    .. versionchanged:: 4.3 
+       Now accepts any yieldable object, not just 
+       `tornado.concurrent.Future`. 
+    """ 
+    tornado_future = convert_yielded(tornado_future) 
+    af = asyncio.Future() 
+    tornado.concurrent.chain_future(tornado_future, af) 
+    return af 
+ 
+ 
+if hasattr(convert_yielded, 'register'): 
+    convert_yielded.register(asyncio.Future, to_tornado_future)  # type: ignore 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/auto.py b/contrib/python/tornado/tornado-4/tornado/platform/auto.py
index 1f4d700193..6a1a2d8fa4 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/auto.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/auto.py
@@ -1,59 +1,59 @@
-#!/usr/bin/env python
-#
-# Copyright 2011 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Implementation of platform-specific functionality.
-
-For each function or class described in `tornado.platform.interface`,
-the appropriate platform-specific implementation exists in this module.
-Most code that needs access to this functionality should do e.g.::
-
-    from tornado.platform.auto import set_close_exec
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import os
-
-if 'APPENGINE_RUNTIME' in os.environ:
-    from tornado.platform.common import Waker
-
-    def set_close_exec(fd):
-        pass
-elif os.name == 'nt':
-    from tornado.platform.common import Waker
-    from tornado.platform.windows import set_close_exec
-else:
-    from tornado.platform.posix import set_close_exec, Waker
-
-try:
-    # monotime monkey-patches the time module to have a monotonic function
-    # in versions of python before 3.3.
-    import monotime
-    # Silence pyflakes warning about this unused import
-    monotime
-except ImportError:
-    pass
-try:
-    # monotonic can provide a monotonic function in versions of python before
-    # 3.3, too.
-    from monotonic import monotonic as monotonic_time
-except ImportError:
-    try:
-        from time import monotonic as monotonic_time
-    except ImportError:
-        monotonic_time = None
-
-__all__ = ['Waker', 'set_close_exec', 'monotonic_time']
+#!/usr/bin/env python 
+# 
+# Copyright 2011 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Implementation of platform-specific functionality. 
+ 
+For each function or class described in `tornado.platform.interface`, 
+the appropriate platform-specific implementation exists in this module. 
+Most code that needs access to this functionality should do e.g.:: 
+ 
+    from tornado.platform.auto import set_close_exec 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import os 
+ 
+if 'APPENGINE_RUNTIME' in os.environ: 
+    from tornado.platform.common import Waker 
+ 
+    def set_close_exec(fd): 
+        pass 
+elif os.name == 'nt': 
+    from tornado.platform.common import Waker 
+    from tornado.platform.windows import set_close_exec 
+else: 
+    from tornado.platform.posix import set_close_exec, Waker 
+ 
+try: 
+    # monotime monkey-patches the time module to have a monotonic function 
+    # in versions of python before 3.3. 
+    import monotime 
+    # Silence pyflakes warning about this unused import 
+    monotime 
+except ImportError: 
+    pass 
+try: 
+    # monotonic can provide a monotonic function in versions of python before 
+    # 3.3, too. 
+    from monotonic import monotonic as monotonic_time 
+except ImportError: 
+    try: 
+        from time import monotonic as monotonic_time 
+    except ImportError: 
+        monotonic_time = None 
+ 
+__all__ = ['Waker', 'set_close_exec', 'monotonic_time'] 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/caresresolver.py b/contrib/python/tornado/tornado-4/tornado/platform/caresresolver.py
index fd6e9d2748..3732ca9194 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/caresresolver.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/caresresolver.py
@@ -1,79 +1,79 @@
-from __future__ import absolute_import, division, print_function
-import pycares  # type: ignore
-import socket
-
-from tornado import gen
-from tornado.ioloop import IOLoop
-from tornado.netutil import Resolver, is_valid_ip
-
-
-class CaresResolver(Resolver):
-    """Name resolver based on the c-ares library.
-
-    This is a non-blocking and non-threaded resolver.  It may not produce
-    the same results as the system resolver, but can be used for non-blocking
-    resolution when threads cannot be used.
-
-    c-ares fails to resolve some names when ``family`` is ``AF_UNSPEC``,
-    so it is only recommended for use in ``AF_INET`` (i.e. IPv4).  This is
-    the default for ``tornado.simple_httpclient``, but other libraries
-    may default to ``AF_UNSPEC``.
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-    """
-    def initialize(self, io_loop=None):
-        self.io_loop = io_loop or IOLoop.current()
-        self.channel = pycares.Channel(sock_state_cb=self._sock_state_cb)
-        self.fds = {}
-
-    def _sock_state_cb(self, fd, readable, writable):
-        state = ((IOLoop.READ if readable else 0) |
-                 (IOLoop.WRITE if writable else 0))
-        if not state:
-            self.io_loop.remove_handler(fd)
-            del self.fds[fd]
-        elif fd in self.fds:
-            self.io_loop.update_handler(fd, state)
-            self.fds[fd] = state
-        else:
-            self.io_loop.add_handler(fd, self._handle_events, state)
-            self.fds[fd] = state
-
-    def _handle_events(self, fd, events):
-        read_fd = pycares.ARES_SOCKET_BAD
-        write_fd = pycares.ARES_SOCKET_BAD
-        if events & IOLoop.READ:
-            read_fd = fd
-        if events & IOLoop.WRITE:
-            write_fd = fd
-        self.channel.process_fd(read_fd, write_fd)
-
-    @gen.coroutine
-    def resolve(self, host, port, family=0):
-        if is_valid_ip(host):
-            addresses = [host]
-        else:
-            # gethostbyname doesn't take callback as a kwarg
-            self.channel.gethostbyname(host, family, (yield gen.Callback(1)))
-            callback_args = yield gen.Wait(1)
-            assert isinstance(callback_args, gen.Arguments)
-            assert not callback_args.kwargs
-            result, error = callback_args.args
-            if error:
-                raise IOError('C-Ares returned error %s: %s while resolving %s' %
-                              (error, pycares.errno.strerror(error), host))
-            addresses = result.addresses
-        addrinfo = []
-        for address in addresses:
-            if '.' in address:
-                address_family = socket.AF_INET
-            elif ':' in address:
-                address_family = socket.AF_INET6
-            else:
-                address_family = socket.AF_UNSPEC
-            if family != socket.AF_UNSPEC and family != address_family:
-                raise IOError('Requested socket family %d but got %d' %
-                              (family, address_family))
-            addrinfo.append((address_family, (address, port)))
-        raise gen.Return(addrinfo)
+from __future__ import absolute_import, division, print_function 
+import pycares  # type: ignore 
+import socket 
+ 
+from tornado import gen 
+from tornado.ioloop import IOLoop 
+from tornado.netutil import Resolver, is_valid_ip 
+ 
+ 
+class CaresResolver(Resolver): 
+    """Name resolver based on the c-ares library. 
+ 
+    This is a non-blocking and non-threaded resolver.  It may not produce 
+    the same results as the system resolver, but can be used for non-blocking 
+    resolution when threads cannot be used. 
+ 
+    c-ares fails to resolve some names when ``family`` is ``AF_UNSPEC``, 
+    so it is only recommended for use in ``AF_INET`` (i.e. IPv4).  This is 
+    the default for ``tornado.simple_httpclient``, but other libraries 
+    may default to ``AF_UNSPEC``. 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+    """ 
+    def initialize(self, io_loop=None): 
+        self.io_loop = io_loop or IOLoop.current() 
+        self.channel = pycares.Channel(sock_state_cb=self._sock_state_cb) 
+        self.fds = {} 
+ 
+    def _sock_state_cb(self, fd, readable, writable): 
+        state = ((IOLoop.READ if readable else 0) | 
+                 (IOLoop.WRITE if writable else 0)) 
+        if not state: 
+            self.io_loop.remove_handler(fd) 
+            del self.fds[fd] 
+        elif fd in self.fds: 
+            self.io_loop.update_handler(fd, state) 
+            self.fds[fd] = state 
+        else: 
+            self.io_loop.add_handler(fd, self._handle_events, state) 
+            self.fds[fd] = state 
+ 
+    def _handle_events(self, fd, events): 
+        read_fd = pycares.ARES_SOCKET_BAD 
+        write_fd = pycares.ARES_SOCKET_BAD 
+        if events & IOLoop.READ: 
+            read_fd = fd 
+        if events & IOLoop.WRITE: 
+            write_fd = fd 
+        self.channel.process_fd(read_fd, write_fd) 
+ 
+    @gen.coroutine 
+    def resolve(self, host, port, family=0): 
+        if is_valid_ip(host): 
+            addresses = [host] 
+        else: 
+            # gethostbyname doesn't take callback as a kwarg 
+            self.channel.gethostbyname(host, family, (yield gen.Callback(1))) 
+            callback_args = yield gen.Wait(1) 
+            assert isinstance(callback_args, gen.Arguments) 
+            assert not callback_args.kwargs 
+            result, error = callback_args.args 
+            if error: 
+                raise IOError('C-Ares returned error %s: %s while resolving %s' % 
+                              (error, pycares.errno.strerror(error), host)) 
+            addresses = result.addresses 
+        addrinfo = [] 
+        for address in addresses: 
+            if '.' in address: 
+                address_family = socket.AF_INET 
+            elif ':' in address: 
+                address_family = socket.AF_INET6 
+            else: 
+                address_family = socket.AF_UNSPEC 
+            if family != socket.AF_UNSPEC and family != address_family: 
+                raise IOError('Requested socket family %d but got %d' % 
+                              (family, address_family)) 
+            addrinfo.append((address_family, (address, port))) 
+        raise gen.Return(addrinfo) 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/common.py b/contrib/python/tornado/tornado-4/tornado/platform/common.py
index b597748d1f..8cd6c126f5 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/common.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/common.py
@@ -1,113 +1,113 @@
-"""Lowest-common-denominator implementations of platform functionality."""
-from __future__ import absolute_import, division, print_function
-
-import errno
-import socket
-import time
-
-from tornado.platform import interface
-from tornado.util import errno_from_exception
-
-
-def try_close(f):
-    # Avoid issue #875 (race condition when using the file in another
-    # thread).
-    for i in range(10):
-        try:
-            f.close()
-        except IOError:
-            # Yield to another thread
-            time.sleep(1e-3)
-        else:
-            break
-    # Try a last time and let raise
-    f.close()
-
-
-class Waker(interface.Waker):
-    """Create an OS independent asynchronous pipe.
-
-    For use on platforms that don't have os.pipe() (or where pipes cannot
-    be passed to select()), but do have sockets.  This includes Windows
-    and Jython.
-    """
-    def __init__(self):
-        from .auto import set_close_exec
-        # Based on Zope select_trigger.py:
-        # https://github.com/zopefoundation/Zope/blob/master/src/ZServer/medusa/thread/select_trigger.py
-
-        self.writer = socket.socket()
-        set_close_exec(self.writer.fileno())
-        # Disable buffering -- pulling the trigger sends 1 byte,
-        # and we want that sent immediately, to wake up ASAP.
-        self.writer.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
-
-        count = 0
-        while 1:
-            count += 1
-            # Bind to a local port; for efficiency, let the OS pick
-            # a free port for us.
-            # Unfortunately, stress tests showed that we may not
-            # be able to connect to that port ("Address already in
-            # use") despite that the OS picked it.  This appears
-            # to be a race bug in the Windows socket implementation.
-            # So we loop until a connect() succeeds (almost always
-            # on the first try).  See the long thread at
-            # http://mail.zope.org/pipermail/zope/2005-July/160433.html
-            # for hideous details.
-            a = socket.socket()
-            set_close_exec(a.fileno())
-            a.bind(("127.0.0.1", 0))
-            a.listen(1)
-            connect_address = a.getsockname()  # assigned (host, port) pair
-            try:
-                self.writer.connect(connect_address)
-                break    # success
-            except socket.error as detail:
-                if (not hasattr(errno, 'WSAEADDRINUSE') or
-                        errno_from_exception(detail) != errno.WSAEADDRINUSE):
-                    # "Address already in use" is the only error
-                    # I've seen on two WinXP Pro SP2 boxes, under
-                    # Pythons 2.3.5 and 2.4.1.
-                    raise
-                # (10048, 'Address already in use')
-                # assert count <= 2 # never triggered in Tim's tests
-                if count >= 10:  # I've never seen it go above 2
-                    a.close()
-                    self.writer.close()
-                    raise socket.error("Cannot bind trigger!")
-                # Close `a` and try again.  Note:  I originally put a short
-                # sleep() here, but it didn't appear to help or hurt.
-                a.close()
-
-        self.reader, addr = a.accept()
-        set_close_exec(self.reader.fileno())
-        self.reader.setblocking(0)
-        self.writer.setblocking(0)
-        a.close()
-        self.reader_fd = self.reader.fileno()
-
-    def fileno(self):
-        return self.reader.fileno()
-
-    def write_fileno(self):
-        return self.writer.fileno()
-
-    def wake(self):
-        try:
-            self.writer.send(b"x")
-        except (IOError, socket.error, ValueError):
-            pass
-
-    def consume(self):
-        try:
-            while True:
-                result = self.reader.recv(1024)
-                if not result:
-                    break
-        except (IOError, socket.error):
-            pass
-
-    def close(self):
-        self.reader.close()
-        try_close(self.writer)
+"""Lowest-common-denominator implementations of platform functionality.""" 
+from __future__ import absolute_import, division, print_function 
+ 
+import errno 
+import socket 
+import time 
+ 
+from tornado.platform import interface 
+from tornado.util import errno_from_exception 
+ 
+ 
+def try_close(f): 
+    # Avoid issue #875 (race condition when using the file in another 
+    # thread). 
+    for i in range(10): 
+        try: 
+            f.close() 
+        except IOError: 
+            # Yield to another thread 
+            time.sleep(1e-3) 
+        else: 
+            break 
+    # Try a last time and let raise 
+    f.close() 
+ 
+ 
+class Waker(interface.Waker): 
+    """Create an OS independent asynchronous pipe. 
+ 
+    For use on platforms that don't have os.pipe() (or where pipes cannot 
+    be passed to select()), but do have sockets.  This includes Windows 
+    and Jython. 
+    """ 
+    def __init__(self): 
+        from .auto import set_close_exec 
+        # Based on Zope select_trigger.py: 
+        # https://github.com/zopefoundation/Zope/blob/master/src/ZServer/medusa/thread/select_trigger.py 
+ 
+        self.writer = socket.socket() 
+        set_close_exec(self.writer.fileno()) 
+        # Disable buffering -- pulling the trigger sends 1 byte, 
+        # and we want that sent immediately, to wake up ASAP. 
+        self.writer.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1) 
+ 
+        count = 0 
+        while 1: 
+            count += 1 
+            # Bind to a local port; for efficiency, let the OS pick 
+            # a free port for us. 
+            # Unfortunately, stress tests showed that we may not 
+            # be able to connect to that port ("Address already in 
+            # use") despite that the OS picked it.  This appears 
+            # to be a race bug in the Windows socket implementation. 
+            # So we loop until a connect() succeeds (almost always 
+            # on the first try).  See the long thread at 
+            # http://mail.zope.org/pipermail/zope/2005-July/160433.html 
+            # for hideous details. 
+            a = socket.socket() 
+            set_close_exec(a.fileno()) 
+            a.bind(("127.0.0.1", 0)) 
+            a.listen(1) 
+            connect_address = a.getsockname()  # assigned (host, port) pair 
+            try: 
+                self.writer.connect(connect_address) 
+                break    # success 
+            except socket.error as detail: 
+                if (not hasattr(errno, 'WSAEADDRINUSE') or 
+                        errno_from_exception(detail) != errno.WSAEADDRINUSE): 
+                    # "Address already in use" is the only error 
+                    # I've seen on two WinXP Pro SP2 boxes, under 
+                    # Pythons 2.3.5 and 2.4.1. 
+                    raise 
+                # (10048, 'Address already in use') 
+                # assert count <= 2 # never triggered in Tim's tests 
+                if count >= 10:  # I've never seen it go above 2 
+                    a.close() 
+                    self.writer.close() 
+                    raise socket.error("Cannot bind trigger!") 
+                # Close `a` and try again.  Note:  I originally put a short 
+                # sleep() here, but it didn't appear to help or hurt. 
+                a.close() 
+ 
+        self.reader, addr = a.accept() 
+        set_close_exec(self.reader.fileno()) 
+        self.reader.setblocking(0) 
+        self.writer.setblocking(0) 
+        a.close() 
+        self.reader_fd = self.reader.fileno() 
+ 
+    def fileno(self): 
+        return self.reader.fileno() 
+ 
+    def write_fileno(self): 
+        return self.writer.fileno() 
+ 
+    def wake(self): 
+        try: 
+            self.writer.send(b"x") 
+        except (IOError, socket.error, ValueError): 
+            pass 
+ 
+    def consume(self): 
+        try: 
+            while True: 
+                result = self.reader.recv(1024) 
+                if not result: 
+                    break 
+        except (IOError, socket.error): 
+            pass 
+ 
+    def close(self): 
+        self.reader.close() 
+        try_close(self.writer) 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/epoll.py b/contrib/python/tornado/tornado-4/tornado/platform/epoll.py
index 80bfd8af4c..a5d17c6c51 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/epoll.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/epoll.py
@@ -1,26 +1,26 @@
-#!/usr/bin/env python
-#
-# Copyright 2012 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-"""EPoll-based IOLoop implementation for Linux systems."""
-from __future__ import absolute_import, division, print_function
-
-import select
-
-from tornado.ioloop import PollIOLoop
-
-
-class EPollIOLoop(PollIOLoop):
-    def initialize(self, **kwargs):
-        super(EPollIOLoop, self).initialize(impl=select.epoll(), **kwargs)
+#!/usr/bin/env python 
+# 
+# Copyright 2012 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+"""EPoll-based IOLoop implementation for Linux systems.""" 
+from __future__ import absolute_import, division, print_function 
+ 
+import select 
+ 
+from tornado.ioloop import PollIOLoop 
+ 
+ 
+class EPollIOLoop(PollIOLoop): 
+    def initialize(self, **kwargs): 
+        super(EPollIOLoop, self).initialize(impl=select.epoll(), **kwargs) 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/interface.py b/contrib/python/tornado/tornado-4/tornado/platform/interface.py
index c0ef2905c3..682351274b 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/interface.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/interface.py
@@ -1,67 +1,67 @@
-#!/usr/bin/env python
-#
-# Copyright 2011 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Interfaces for platform-specific functionality.
-
-This module exists primarily for documentation purposes and as base classes
-for other tornado.platform modules.  Most code should import the appropriate
-implementation from `tornado.platform.auto`.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-
-def set_close_exec(fd):
-    """Sets the close-on-exec bit (``FD_CLOEXEC``)for a file descriptor."""
-    raise NotImplementedError()
-
-
-class Waker(object):
-    """A socket-like object that can wake another thread from ``select()``.
-
-    The `~tornado.ioloop.IOLoop` will add the Waker's `fileno()` to
-    its ``select`` (or ``epoll`` or ``kqueue``) calls.  When another
-    thread wants to wake up the loop, it calls `wake`.  Once it has woken
-    up, it will call `consume` to do any necessary per-wake cleanup.  When
-    the ``IOLoop`` is closed, it closes its waker too.
-    """
-    def fileno(self):
-        """Returns the read file descriptor for this waker.
-
-        Must be suitable for use with ``select()`` or equivalent on the
-        local platform.
-        """
-        raise NotImplementedError()
-
-    def write_fileno(self):
-        """Returns the write file descriptor for this waker."""
-        raise NotImplementedError()
-
-    def wake(self):
-        """Triggers activity on the waker's file descriptor."""
-        raise NotImplementedError()
-
-    def consume(self):
-        """Called after the listen has woken up to do any necessary cleanup."""
-        raise NotImplementedError()
-
-    def close(self):
-        """Closes the waker's file descriptor(s)."""
-        raise NotImplementedError()
-
-
-def monotonic_time():
-    raise NotImplementedError()
+#!/usr/bin/env python 
+# 
+# Copyright 2011 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Interfaces for platform-specific functionality. 
+ 
+This module exists primarily for documentation purposes and as base classes 
+for other tornado.platform modules.  Most code should import the appropriate 
+implementation from `tornado.platform.auto`. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+ 
+def set_close_exec(fd): 
+    """Sets the close-on-exec bit (``FD_CLOEXEC``)for a file descriptor.""" 
+    raise NotImplementedError() 
+ 
+ 
+class Waker(object): 
+    """A socket-like object that can wake another thread from ``select()``. 
+ 
+    The `~tornado.ioloop.IOLoop` will add the Waker's `fileno()` to 
+    its ``select`` (or ``epoll`` or ``kqueue``) calls.  When another 
+    thread wants to wake up the loop, it calls `wake`.  Once it has woken 
+    up, it will call `consume` to do any necessary per-wake cleanup.  When 
+    the ``IOLoop`` is closed, it closes its waker too. 
+    """ 
+    def fileno(self): 
+        """Returns the read file descriptor for this waker. 
+ 
+        Must be suitable for use with ``select()`` or equivalent on the 
+        local platform. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def write_fileno(self): 
+        """Returns the write file descriptor for this waker.""" 
+        raise NotImplementedError() 
+ 
+    def wake(self): 
+        """Triggers activity on the waker's file descriptor.""" 
+        raise NotImplementedError() 
+ 
+    def consume(self): 
+        """Called after the listen has woken up to do any necessary cleanup.""" 
+        raise NotImplementedError() 
+ 
+    def close(self): 
+        """Closes the waker's file descriptor(s).""" 
+        raise NotImplementedError() 
+ 
+ 
+def monotonic_time(): 
+    raise NotImplementedError() 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/kqueue.py b/contrib/python/tornado/tornado-4/tornado/platform/kqueue.py
index 3a5d417429..d10b07c230 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/kqueue.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/kqueue.py
@@ -1,91 +1,91 @@
-#!/usr/bin/env python
-#
-# Copyright 2012 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-"""KQueue-based IOLoop implementation for BSD/Mac systems."""
-from __future__ import absolute_import, division, print_function
-
-import select
-
-from tornado.ioloop import IOLoop, PollIOLoop
-
-assert hasattr(select, 'kqueue'), 'kqueue not supported'
-
-
-class _KQueue(object):
-    """A kqueue-based event loop for BSD/Mac systems."""
-    def __init__(self):
-        self._kqueue = select.kqueue()
-        self._active = {}
-
-    def fileno(self):
-        return self._kqueue.fileno()
-
-    def close(self):
-        self._kqueue.close()
-
-    def register(self, fd, events):
-        if fd in self._active:
-            raise IOError("fd %s already registered" % fd)
-        self._control(fd, events, select.KQ_EV_ADD)
-        self._active[fd] = events
-
-    def modify(self, fd, events):
-        self.unregister(fd)
-        self.register(fd, events)
-
-    def unregister(self, fd):
-        events = self._active.pop(fd)
-        self._control(fd, events, select.KQ_EV_DELETE)
-
-    def _control(self, fd, events, flags):
-        kevents = []
-        if events & IOLoop.WRITE:
-            kevents.append(select.kevent(
-                fd, filter=select.KQ_FILTER_WRITE, flags=flags))
-        if events & IOLoop.READ:
-            kevents.append(select.kevent(
-                fd, filter=select.KQ_FILTER_READ, flags=flags))
-        # Even though control() takes a list, it seems to return EINVAL
-        # on Mac OS X (10.6) when there is more than one event in the list.
-        for kevent in kevents:
-            self._kqueue.control([kevent], 0)
-
-    def poll(self, timeout):
-        kevents = self._kqueue.control(None, 1000, timeout)
-        events = {}
-        for kevent in kevents:
-            fd = kevent.ident
-            if kevent.filter == select.KQ_FILTER_READ:
-                events[fd] = events.get(fd, 0) | IOLoop.READ
-            if kevent.filter == select.KQ_FILTER_WRITE:
-                if kevent.flags & select.KQ_EV_EOF:
-                    # If an asynchronous connection is refused, kqueue
-                    # returns a write event with the EOF flag set.
-                    # Turn this into an error for consistency with the
-                    # other IOLoop implementations.
-                    # Note that for read events, EOF may be returned before
-                    # all data has been consumed from the socket buffer,
-                    # so we only check for EOF on write events.
-                    events[fd] = IOLoop.ERROR
-                else:
-                    events[fd] = events.get(fd, 0) | IOLoop.WRITE
-            if kevent.flags & select.KQ_EV_ERROR:
-                events[fd] = events.get(fd, 0) | IOLoop.ERROR
-        return events.items()
-
-
-class KQueueIOLoop(PollIOLoop):
-    def initialize(self, **kwargs):
-        super(KQueueIOLoop, self).initialize(impl=_KQueue(), **kwargs)
+#!/usr/bin/env python 
+# 
+# Copyright 2012 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+"""KQueue-based IOLoop implementation for BSD/Mac systems.""" 
+from __future__ import absolute_import, division, print_function 
+ 
+import select 
+ 
+from tornado.ioloop import IOLoop, PollIOLoop 
+ 
+assert hasattr(select, 'kqueue'), 'kqueue not supported' 
+ 
+ 
+class _KQueue(object): 
+    """A kqueue-based event loop for BSD/Mac systems.""" 
+    def __init__(self): 
+        self._kqueue = select.kqueue() 
+        self._active = {} 
+ 
+    def fileno(self): 
+        return self._kqueue.fileno() 
+ 
+    def close(self): 
+        self._kqueue.close() 
+ 
+    def register(self, fd, events): 
+        if fd in self._active: 
+            raise IOError("fd %s already registered" % fd) 
+        self._control(fd, events, select.KQ_EV_ADD) 
+        self._active[fd] = events 
+ 
+    def modify(self, fd, events): 
+        self.unregister(fd) 
+        self.register(fd, events) 
+ 
+    def unregister(self, fd): 
+        events = self._active.pop(fd) 
+        self._control(fd, events, select.KQ_EV_DELETE) 
+ 
+    def _control(self, fd, events, flags): 
+        kevents = [] 
+        if events & IOLoop.WRITE: 
+            kevents.append(select.kevent( 
+                fd, filter=select.KQ_FILTER_WRITE, flags=flags)) 
+        if events & IOLoop.READ: 
+            kevents.append(select.kevent( 
+                fd, filter=select.KQ_FILTER_READ, flags=flags)) 
+        # Even though control() takes a list, it seems to return EINVAL 
+        # on Mac OS X (10.6) when there is more than one event in the list. 
+        for kevent in kevents: 
+            self._kqueue.control([kevent], 0) 
+ 
+    def poll(self, timeout): 
+        kevents = self._kqueue.control(None, 1000, timeout) 
+        events = {} 
+        for kevent in kevents: 
+            fd = kevent.ident 
+            if kevent.filter == select.KQ_FILTER_READ: 
+                events[fd] = events.get(fd, 0) | IOLoop.READ 
+            if kevent.filter == select.KQ_FILTER_WRITE: 
+                if kevent.flags & select.KQ_EV_EOF: 
+                    # If an asynchronous connection is refused, kqueue 
+                    # returns a write event with the EOF flag set. 
+                    # Turn this into an error for consistency with the 
+                    # other IOLoop implementations. 
+                    # Note that for read events, EOF may be returned before 
+                    # all data has been consumed from the socket buffer, 
+                    # so we only check for EOF on write events. 
+                    events[fd] = IOLoop.ERROR 
+                else: 
+                    events[fd] = events.get(fd, 0) | IOLoop.WRITE 
+            if kevent.flags & select.KQ_EV_ERROR: 
+                events[fd] = events.get(fd, 0) | IOLoop.ERROR 
+        return events.items() 
+ 
+ 
+class KQueueIOLoop(PollIOLoop): 
+    def initialize(self, **kwargs): 
+        super(KQueueIOLoop, self).initialize(impl=_KQueue(), **kwargs) 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/posix.py b/contrib/python/tornado/tornado-4/tornado/platform/posix.py
index 9bf1f18868..3ad7634ec2 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/posix.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/posix.py
@@ -1,70 +1,70 @@
-#!/usr/bin/env python
-#
-# Copyright 2011 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Posix implementations of platform-specific functionality."""
-
-from __future__ import absolute_import, division, print_function
-
-import fcntl
-import os
-
-from tornado.platform import common, interface
-
-
-def set_close_exec(fd):
-    flags = fcntl.fcntl(fd, fcntl.F_GETFD)
-    fcntl.fcntl(fd, fcntl.F_SETFD, flags | fcntl.FD_CLOEXEC)
-
-
-def _set_nonblocking(fd):
-    flags = fcntl.fcntl(fd, fcntl.F_GETFL)
-    fcntl.fcntl(fd, fcntl.F_SETFL, flags | os.O_NONBLOCK)
-
-
-class Waker(interface.Waker):
-    def __init__(self):
-        r, w = os.pipe()
-        _set_nonblocking(r)
-        _set_nonblocking(w)
-        set_close_exec(r)
-        set_close_exec(w)
-        self.reader = os.fdopen(r, "rb", 0)
-        self.writer = os.fdopen(w, "wb", 0)
-
-    def fileno(self):
-        return self.reader.fileno()
-
-    def write_fileno(self):
-        return self.writer.fileno()
-
-    def wake(self):
-        try:
-            self.writer.write(b"x")
-        except (IOError, ValueError):
-            pass
-
-    def consume(self):
-        try:
-            while True:
-                result = self.reader.read()
-                if not result:
-                    break
-        except IOError:
-            pass
-
-    def close(self):
-        self.reader.close()
-        common.try_close(self.writer)
+#!/usr/bin/env python 
+# 
+# Copyright 2011 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Posix implementations of platform-specific functionality.""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import fcntl 
+import os 
+ 
+from tornado.platform import common, interface 
+ 
+ 
+def set_close_exec(fd): 
+    flags = fcntl.fcntl(fd, fcntl.F_GETFD) 
+    fcntl.fcntl(fd, fcntl.F_SETFD, flags | fcntl.FD_CLOEXEC) 
+ 
+ 
+def _set_nonblocking(fd): 
+    flags = fcntl.fcntl(fd, fcntl.F_GETFL) 
+    fcntl.fcntl(fd, fcntl.F_SETFL, flags | os.O_NONBLOCK) 
+ 
+ 
+class Waker(interface.Waker): 
+    def __init__(self): 
+        r, w = os.pipe() 
+        _set_nonblocking(r) 
+        _set_nonblocking(w) 
+        set_close_exec(r) 
+        set_close_exec(w) 
+        self.reader = os.fdopen(r, "rb", 0) 
+        self.writer = os.fdopen(w, "wb", 0) 
+ 
+    def fileno(self): 
+        return self.reader.fileno() 
+ 
+    def write_fileno(self): 
+        return self.writer.fileno() 
+ 
+    def wake(self): 
+        try: 
+            self.writer.write(b"x") 
+        except (IOError, ValueError): 
+            pass 
+ 
+    def consume(self): 
+        try: 
+            while True: 
+                result = self.reader.read() 
+                if not result: 
+                    break 
+        except IOError: 
+            pass 
+ 
+    def close(self): 
+        self.reader.close() 
+        common.try_close(self.writer) 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/select.py b/contrib/python/tornado/tornado-4/tornado/platform/select.py
index a18049f7cd..2dd66654c5 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/select.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/select.py
@@ -1,76 +1,76 @@
-#!/usr/bin/env python
-#
-# Copyright 2012 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-"""Select-based IOLoop implementation.
-
-Used as a fallback for systems that don't support epoll or kqueue.
-"""
-from __future__ import absolute_import, division, print_function
-
-import select
-
-from tornado.ioloop import IOLoop, PollIOLoop
-
-
-class _Select(object):
-    """A simple, select()-based IOLoop implementation for non-Linux systems"""
-    def __init__(self):
-        self.read_fds = set()
-        self.write_fds = set()
-        self.error_fds = set()
-        self.fd_sets = (self.read_fds, self.write_fds, self.error_fds)
-
-    def close(self):
-        pass
-
-    def register(self, fd, events):
-        if fd in self.read_fds or fd in self.write_fds or fd in self.error_fds:
-            raise IOError("fd %s already registered" % fd)
-        if events & IOLoop.READ:
-            self.read_fds.add(fd)
-        if events & IOLoop.WRITE:
-            self.write_fds.add(fd)
-        if events & IOLoop.ERROR:
-            self.error_fds.add(fd)
-            # Closed connections are reported as errors by epoll and kqueue,
-            # but as zero-byte reads by select, so when errors are requested
-            # we need to listen for both read and error.
-            # self.read_fds.add(fd)
-
-    def modify(self, fd, events):
-        self.unregister(fd)
-        self.register(fd, events)
-
-    def unregister(self, fd):
-        self.read_fds.discard(fd)
-        self.write_fds.discard(fd)
-        self.error_fds.discard(fd)
-
-    def poll(self, timeout):
-        readable, writeable, errors = select.select(
-            self.read_fds, self.write_fds, self.error_fds, timeout)
-        events = {}
-        for fd in readable:
-            events[fd] = events.get(fd, 0) | IOLoop.READ
-        for fd in writeable:
-            events[fd] = events.get(fd, 0) | IOLoop.WRITE
-        for fd in errors:
-            events[fd] = events.get(fd, 0) | IOLoop.ERROR
-        return events.items()
-
-
-class SelectIOLoop(PollIOLoop):
-    def initialize(self, **kwargs):
-        super(SelectIOLoop, self).initialize(impl=_Select(), **kwargs)
+#!/usr/bin/env python 
+# 
+# Copyright 2012 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+"""Select-based IOLoop implementation. 
+ 
+Used as a fallback for systems that don't support epoll or kqueue. 
+""" 
+from __future__ import absolute_import, division, print_function 
+ 
+import select 
+ 
+from tornado.ioloop import IOLoop, PollIOLoop 
+ 
+ 
+class _Select(object): 
+    """A simple, select()-based IOLoop implementation for non-Linux systems""" 
+    def __init__(self): 
+        self.read_fds = set() 
+        self.write_fds = set() 
+        self.error_fds = set() 
+        self.fd_sets = (self.read_fds, self.write_fds, self.error_fds) 
+ 
+    def close(self): 
+        pass 
+ 
+    def register(self, fd, events): 
+        if fd in self.read_fds or fd in self.write_fds or fd in self.error_fds: 
+            raise IOError("fd %s already registered" % fd) 
+        if events & IOLoop.READ: 
+            self.read_fds.add(fd) 
+        if events & IOLoop.WRITE: 
+            self.write_fds.add(fd) 
+        if events & IOLoop.ERROR: 
+            self.error_fds.add(fd) 
+            # Closed connections are reported as errors by epoll and kqueue, 
+            # but as zero-byte reads by select, so when errors are requested 
+            # we need to listen for both read and error. 
+            # self.read_fds.add(fd) 
+ 
+    def modify(self, fd, events): 
+        self.unregister(fd) 
+        self.register(fd, events) 
+ 
+    def unregister(self, fd): 
+        self.read_fds.discard(fd) 
+        self.write_fds.discard(fd) 
+        self.error_fds.discard(fd) 
+ 
+    def poll(self, timeout): 
+        readable, writeable, errors = select.select( 
+            self.read_fds, self.write_fds, self.error_fds, timeout) 
+        events = {} 
+        for fd in readable: 
+            events[fd] = events.get(fd, 0) | IOLoop.READ 
+        for fd in writeable: 
+            events[fd] = events.get(fd, 0) | IOLoop.WRITE 
+        for fd in errors: 
+            events[fd] = events.get(fd, 0) | IOLoop.ERROR 
+        return events.items() 
+ 
+ 
+class SelectIOLoop(PollIOLoop): 
+    def initialize(self, **kwargs): 
+        super(SelectIOLoop, self).initialize(impl=_Select(), **kwargs) 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/twisted.py b/contrib/python/tornado/tornado-4/tornado/platform/twisted.py
index 0f9787e84d..7e1b18d84c 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/twisted.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/twisted.py
@@ -1,591 +1,591 @@
-# Author: Ovidiu Predescu
-# Date: July 2011
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-"""Bridges between the Twisted reactor and Tornado IOLoop.
-
-This module lets you run applications and libraries written for
-Twisted in a Tornado application.  It can be used in two modes,
-depending on which library's underlying event loop you want to use.
-
-This module has been tested with Twisted versions 11.0.0 and newer.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import datetime
-import functools
-import numbers
-import socket
-import sys
-
-import twisted.internet.abstract  # type: ignore
-from twisted.internet.defer import Deferred  # type: ignore
-from twisted.internet.posixbase import PosixReactorBase  # type: ignore
-from twisted.internet.interfaces import IReactorFDSet, IDelayedCall, IReactorTime, IReadDescriptor, IWriteDescriptor  # type: ignore
-from twisted.python import failure, log  # type: ignore
-from twisted.internet import error  # type: ignore
-import twisted.names.cache  # type: ignore
-import twisted.names.client  # type: ignore
-import twisted.names.hosts  # type: ignore
-import twisted.names.resolve  # type: ignore
-
-from zope.interface import implementer  # type: ignore
-
-from tornado.concurrent import Future
-from tornado.escape import utf8
-from tornado import gen
-import tornado.ioloop
-from tornado.log import app_log
-from tornado.netutil import Resolver
-from tornado.stack_context import NullContext, wrap
-from tornado.ioloop import IOLoop
-from tornado.util import timedelta_to_seconds
-
-
-@implementer(IDelayedCall)
-class TornadoDelayedCall(object):
-    """DelayedCall object for Tornado."""
-    def __init__(self, reactor, seconds, f, *args, **kw):
-        self._reactor = reactor
-        self._func = functools.partial(f, *args, **kw)
-        self._time = self._reactor.seconds() + seconds
-        self._timeout = self._reactor._io_loop.add_timeout(self._time,
-                                                           self._called)
-        self._active = True
-
-    def _called(self):
-        self._active = False
-        self._reactor._removeDelayedCall(self)
-        try:
-            self._func()
-        except:
-            app_log.error("_called caught exception", exc_info=True)
-
-    def getTime(self):
-        return self._time
-
-    def cancel(self):
-        self._active = False
-        self._reactor._io_loop.remove_timeout(self._timeout)
-        self._reactor._removeDelayedCall(self)
-
-    def delay(self, seconds):
-        self._reactor._io_loop.remove_timeout(self._timeout)
-        self._time += seconds
-        self._timeout = self._reactor._io_loop.add_timeout(self._time,
-                                                           self._called)
-
-    def reset(self, seconds):
-        self._reactor._io_loop.remove_timeout(self._timeout)
-        self._time = self._reactor.seconds() + seconds
-        self._timeout = self._reactor._io_loop.add_timeout(self._time,
-                                                           self._called)
-
-    def active(self):
-        return self._active
-
-
-@implementer(IReactorTime, IReactorFDSet)
-class TornadoReactor(PosixReactorBase):
-    """Twisted reactor built on the Tornado IOLoop.
-
-    `TornadoReactor` implements the Twisted reactor interface on top of
-    the Tornado IOLoop.  To use it, simply call `install` at the beginning
-    of the application::
-
-        import tornado.platform.twisted
-        tornado.platform.twisted.install()
-        from twisted.internet import reactor
-
-    When the app is ready to start, call ``IOLoop.current().start()``
-    instead of ``reactor.run()``.
-
-    It is also possible to create a non-global reactor by calling
-    ``tornado.platform.twisted.TornadoReactor(io_loop)``.  However, if
-    the `.IOLoop` and reactor are to be short-lived (such as those used in
-    unit tests), additional cleanup may be required.  Specifically, it is
-    recommended to call::
-
-        reactor.fireSystemEvent('shutdown')
-        reactor.disconnectAll()
-
-    before closing the `.IOLoop`.
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-    """
-    def __init__(self, io_loop=None):
-        if not io_loop:
-            io_loop = tornado.ioloop.IOLoop.current()
-        self._io_loop = io_loop
-        self._readers = {}  # map of reader objects to fd
-        self._writers = {}  # map of writer objects to fd
-        self._fds = {}  # a map of fd to a (reader, writer) tuple
-        self._delayedCalls = {}
-        PosixReactorBase.__init__(self)
-        self.addSystemEventTrigger('during', 'shutdown', self.crash)
-
-        # IOLoop.start() bypasses some of the reactor initialization.
-        # Fire off the necessary events if they weren't already triggered
-        # by reactor.run().
-        def start_if_necessary():
-            if not self._started:
-                self.fireSystemEvent('startup')
-        self._io_loop.add_callback(start_if_necessary)
-
-    # IReactorTime
-    def seconds(self):
-        return self._io_loop.time()
-
-    def callLater(self, seconds, f, *args, **kw):
-        dc = TornadoDelayedCall(self, seconds, f, *args, **kw)
-        self._delayedCalls[dc] = True
-        return dc
-
-    def getDelayedCalls(self):
-        return [x for x in self._delayedCalls if x._active]
-
-    def _removeDelayedCall(self, dc):
-        if dc in self._delayedCalls:
-            del self._delayedCalls[dc]
-
-    # IReactorThreads
-    def callFromThread(self, f, *args, **kw):
-        assert callable(f), "%s is not callable" % f
-        with NullContext():
-            # This NullContext is mainly for an edge case when running
-            # TwistedIOLoop on top of a TornadoReactor.
-            # TwistedIOLoop.add_callback uses reactor.callFromThread and
-            # should not pick up additional StackContexts along the way.
-            self._io_loop.add_callback(f, *args, **kw)
-
-    # We don't need the waker code from the super class, Tornado uses
-    # its own waker.
-    def installWaker(self):
-        pass
-
-    def wakeUp(self):
-        pass
-
-    # IReactorFDSet
-    def _invoke_callback(self, fd, events):
-        if fd not in self._fds:
-            return
-        (reader, writer) = self._fds[fd]
-        if reader:
-            err = None
-            if reader.fileno() == -1:
-                err = error.ConnectionLost()
-            elif events & IOLoop.READ:
-                err = log.callWithLogger(reader, reader.doRead)
-            if err is None and events & IOLoop.ERROR:
-                err = error.ConnectionLost()
-            if err is not None:
-                self.removeReader(reader)
-                reader.readConnectionLost(failure.Failure(err))
-        if writer:
-            err = None
-            if writer.fileno() == -1:
-                err = error.ConnectionLost()
-            elif events & IOLoop.WRITE:
-                err = log.callWithLogger(writer, writer.doWrite)
-            if err is None and events & IOLoop.ERROR:
-                err = error.ConnectionLost()
-            if err is not None:
-                self.removeWriter(writer)
-                writer.writeConnectionLost(failure.Failure(err))
-
-    def addReader(self, reader):
-        if reader in self._readers:
-            # Don't add the reader if it's already there
-            return
-        fd = reader.fileno()
-        self._readers[reader] = fd
-        if fd in self._fds:
-            (_, writer) = self._fds[fd]
-            self._fds[fd] = (reader, writer)
-            if writer:
-                # We already registered this fd for write events,
-                # update it for read events as well.
-                self._io_loop.update_handler(fd, IOLoop.READ | IOLoop.WRITE)
-        else:
-            with NullContext():
-                self._fds[fd] = (reader, None)
-                self._io_loop.add_handler(fd, self._invoke_callback,
-                                          IOLoop.READ)
-
-    def addWriter(self, writer):
-        if writer in self._writers:
-            return
-        fd = writer.fileno()
-        self._writers[writer] = fd
-        if fd in self._fds:
-            (reader, _) = self._fds[fd]
-            self._fds[fd] = (reader, writer)
-            if reader:
-                # We already registered this fd for read events,
-                # update it for write events as well.
-                self._io_loop.update_handler(fd, IOLoop.READ | IOLoop.WRITE)
-        else:
-            with NullContext():
-                self._fds[fd] = (None, writer)
-                self._io_loop.add_handler(fd, self._invoke_callback,
-                                          IOLoop.WRITE)
-
-    def removeReader(self, reader):
-        if reader in self._readers:
-            fd = self._readers.pop(reader)
-            (_, writer) = self._fds[fd]
-            if writer:
-                # We have a writer so we need to update the IOLoop for
-                # write events only.
-                self._fds[fd] = (None, writer)
-                self._io_loop.update_handler(fd, IOLoop.WRITE)
-            else:
-                # Since we have no writer registered, we remove the
-                # entry from _fds and unregister the handler from the
-                # IOLoop
-                del self._fds[fd]
-                self._io_loop.remove_handler(fd)
-
-    def removeWriter(self, writer):
-        if writer in self._writers:
-            fd = self._writers.pop(writer)
-            (reader, _) = self._fds[fd]
-            if reader:
-                # We have a reader so we need to update the IOLoop for
-                # read events only.
-                self._fds[fd] = (reader, None)
-                self._io_loop.update_handler(fd, IOLoop.READ)
-            else:
-                # Since we have no reader registered, we remove the
-                # entry from the _fds and unregister the handler from
-                # the IOLoop.
-                del self._fds[fd]
-                self._io_loop.remove_handler(fd)
-
-    def removeAll(self):
-        return self._removeAll(self._readers, self._writers)
-
-    def getReaders(self):
-        return self._readers.keys()
-
-    def getWriters(self):
-        return self._writers.keys()
-
-    # The following functions are mainly used in twisted-style test cases;
-    # it is expected that most users of the TornadoReactor will call
-    # IOLoop.start() instead of Reactor.run().
-    def stop(self):
-        PosixReactorBase.stop(self)
-        fire_shutdown = functools.partial(self.fireSystemEvent, "shutdown")
-        self._io_loop.add_callback(fire_shutdown)
-
-    def crash(self):
-        PosixReactorBase.crash(self)
-        self._io_loop.stop()
-
-    def doIteration(self, delay):
-        raise NotImplementedError("doIteration")
-
-    def mainLoop(self):
-        # Since this class is intended to be used in applications
-        # where the top-level event loop is ``io_loop.start()`` rather
-        # than ``reactor.run()``, it is implemented a little
-        # differently than other Twisted reactors. We override
-        # ``mainLoop`` instead of ``doIteration`` and must implement
-        # timed call functionality on top of `.IOLoop.add_timeout`
-        # rather than using the implementation in
-        # ``PosixReactorBase``.
-        self._io_loop.start()
-
-
-class _TestReactor(TornadoReactor):
-    """Subclass of TornadoReactor for use in unittests.
-
-    This can't go in the test.py file because of import-order dependencies
-    with the Twisted reactor test builder.
-    """
-    def __init__(self):
-        # always use a new ioloop
-        super(_TestReactor, self).__init__(IOLoop())
-
-    def listenTCP(self, port, factory, backlog=50, interface=''):
-        # default to localhost to avoid firewall prompts on the mac
-        if not interface:
-            interface = '127.0.0.1'
-        return super(_TestReactor, self).listenTCP(
-            port, factory, backlog=backlog, interface=interface)
-
-    def listenUDP(self, port, protocol, interface='', maxPacketSize=8192):
-        if not interface:
-            interface = '127.0.0.1'
-        return super(_TestReactor, self).listenUDP(
-            port, protocol, interface=interface, maxPacketSize=maxPacketSize)
-
-
-def install(io_loop=None):
-    """Install this package as the default Twisted reactor.
-
-    ``install()`` must be called very early in the startup process,
-    before most other twisted-related imports. Conversely, because it
-    initializes the `.IOLoop`, it cannot be called before
-    `.fork_processes` or multi-process `~.TCPServer.start`. These
-    conflicting requirements make it difficult to use `.TornadoReactor`
-    in multi-process mode, and an external process manager such as
-    ``supervisord`` is recommended instead.
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-
-    """
-    if not io_loop:
-        io_loop = tornado.ioloop.IOLoop.current()
-    reactor = TornadoReactor(io_loop)
-    from twisted.internet.main import installReactor  # type: ignore
-    installReactor(reactor)
-    return reactor
-
-
-@implementer(IReadDescriptor, IWriteDescriptor)
-class _FD(object):
-    def __init__(self, fd, fileobj, handler):
-        self.fd = fd
-        self.fileobj = fileobj
-        self.handler = handler
-        self.reading = False
-        self.writing = False
-        self.lost = False
-
-    def fileno(self):
-        return self.fd
-
-    def doRead(self):
-        if not self.lost:
-            self.handler(self.fileobj, tornado.ioloop.IOLoop.READ)
-
-    def doWrite(self):
-        if not self.lost:
-            self.handler(self.fileobj, tornado.ioloop.IOLoop.WRITE)
-
-    def connectionLost(self, reason):
-        if not self.lost:
-            self.handler(self.fileobj, tornado.ioloop.IOLoop.ERROR)
-            self.lost = True
-
-    def logPrefix(self):
-        return ''
-
-
-class TwistedIOLoop(tornado.ioloop.IOLoop):
-    """IOLoop implementation that runs on Twisted.
-
-    `TwistedIOLoop` implements the Tornado IOLoop interface on top of
-    the Twisted reactor. Recommended usage::
-
-        from tornado.platform.twisted import TwistedIOLoop
-        from twisted.internet import reactor
-        TwistedIOLoop().install()
-        # Set up your tornado application as usual using `IOLoop.instance`
-        reactor.run()
-
-    Uses the global Twisted reactor by default.  To create multiple
-    ``TwistedIOLoops`` in the same process, you must pass a unique reactor
-    when constructing each one.
-
-    Not compatible with `tornado.process.Subprocess.set_exit_callback`
-    because the ``SIGCHLD`` handlers used by Tornado and Twisted conflict
-    with each other.
-
-    See also :meth:`tornado.ioloop.IOLoop.install` for general notes on
-    installing alternative IOLoops.
-    """
-    def initialize(self, reactor=None, **kwargs):
-        super(TwistedIOLoop, self).initialize(**kwargs)
-        if reactor is None:
-            import twisted.internet.reactor  # type: ignore
-            reactor = twisted.internet.reactor
-        self.reactor = reactor
-        self.fds = {}
-
-    def close(self, all_fds=False):
-        fds = self.fds
-        self.reactor.removeAll()
-        for c in self.reactor.getDelayedCalls():
-            c.cancel()
-        if all_fds:
-            for fd in fds.values():
-                self.close_fd(fd.fileobj)
-
-    def add_handler(self, fd, handler, events):
-        if fd in self.fds:
-            raise ValueError('fd %s added twice' % fd)
-        fd, fileobj = self.split_fd(fd)
-        self.fds[fd] = _FD(fd, fileobj, wrap(handler))
-        if events & tornado.ioloop.IOLoop.READ:
-            self.fds[fd].reading = True
-            self.reactor.addReader(self.fds[fd])
-        if events & tornado.ioloop.IOLoop.WRITE:
-            self.fds[fd].writing = True
-            self.reactor.addWriter(self.fds[fd])
-
-    def update_handler(self, fd, events):
-        fd, fileobj = self.split_fd(fd)
-        if events & tornado.ioloop.IOLoop.READ:
-            if not self.fds[fd].reading:
-                self.fds[fd].reading = True
-                self.reactor.addReader(self.fds[fd])
-        else:
-            if self.fds[fd].reading:
-                self.fds[fd].reading = False
-                self.reactor.removeReader(self.fds[fd])
-        if events & tornado.ioloop.IOLoop.WRITE:
-            if not self.fds[fd].writing:
-                self.fds[fd].writing = True
-                self.reactor.addWriter(self.fds[fd])
-        else:
-            if self.fds[fd].writing:
-                self.fds[fd].writing = False
-                self.reactor.removeWriter(self.fds[fd])
-
-    def remove_handler(self, fd):
-        fd, fileobj = self.split_fd(fd)
-        if fd not in self.fds:
-            return
-        self.fds[fd].lost = True
-        if self.fds[fd].reading:
-            self.reactor.removeReader(self.fds[fd])
-        if self.fds[fd].writing:
-            self.reactor.removeWriter(self.fds[fd])
-        del self.fds[fd]
-
-    def start(self):
-        old_current = IOLoop.current(instance=False)
-        try:
-            self._setup_logging()
-            self.make_current()
-            self.reactor.run()
-        finally:
-            if old_current is None:
-                IOLoop.clear_current()
-            else:
-                old_current.make_current()
-
-    def stop(self):
-        self.reactor.crash()
-
-    def add_timeout(self, deadline, callback, *args, **kwargs):
-        # This method could be simplified (since tornado 4.0) by
-        # overriding call_at instead of add_timeout, but we leave it
-        # for now as a test of backwards-compatibility.
-        if isinstance(deadline, numbers.Real):
-            delay = max(deadline - self.time(), 0)
-        elif isinstance(deadline, datetime.timedelta):
-            delay = timedelta_to_seconds(deadline)
-        else:
-            raise TypeError("Unsupported deadline %r")
-        return self.reactor.callLater(
-            delay, self._run_callback,
-            functools.partial(wrap(callback), *args, **kwargs))
-
-    def remove_timeout(self, timeout):
-        if timeout.active():
-            timeout.cancel()
-
-    def add_callback(self, callback, *args, **kwargs):
-        self.reactor.callFromThread(
-            self._run_callback,
-            functools.partial(wrap(callback), *args, **kwargs))
-
-    def add_callback_from_signal(self, callback, *args, **kwargs):
-        self.add_callback(callback, *args, **kwargs)
-
-
-class TwistedResolver(Resolver):
-    """Twisted-based asynchronous resolver.
-
-    This is a non-blocking and non-threaded resolver.  It is
-    recommended only when threads cannot be used, since it has
-    limitations compared to the standard ``getaddrinfo``-based
-    `~tornado.netutil.Resolver` and
-    `~tornado.netutil.ThreadedResolver`.  Specifically, it returns at
-    most one result, and arguments other than ``host`` and ``family``
-    are ignored.  It may fail to resolve when ``family`` is not
-    ``socket.AF_UNSPEC``.
-
-    Requires Twisted 12.1 or newer.
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-    """
-    def initialize(self, io_loop=None):
-        self.io_loop = io_loop or IOLoop.current()
-        # partial copy of twisted.names.client.createResolver, which doesn't
-        # allow for a reactor to be passed in.
-        self.reactor = tornado.platform.twisted.TornadoReactor(io_loop)
-
-        host_resolver = twisted.names.hosts.Resolver('/etc/hosts')
-        cache_resolver = twisted.names.cache.CacheResolver(reactor=self.reactor)
-        real_resolver = twisted.names.client.Resolver('/etc/resolv.conf',
-                                                      reactor=self.reactor)
-        self.resolver = twisted.names.resolve.ResolverChain(
-            [host_resolver, cache_resolver, real_resolver])
-
-    @gen.coroutine
-    def resolve(self, host, port, family=0):
-        # getHostByName doesn't accept IP addresses, so if the input
-        # looks like an IP address just return it immediately.
-        if twisted.internet.abstract.isIPAddress(host):
-            resolved = host
-            resolved_family = socket.AF_INET
-        elif twisted.internet.abstract.isIPv6Address(host):
-            resolved = host
-            resolved_family = socket.AF_INET6
-        else:
-            deferred = self.resolver.getHostByName(utf8(host))
-            resolved = yield gen.Task(deferred.addBoth)
-            if isinstance(resolved, failure.Failure):
-                try:
-                    resolved.raiseException()
-                except twisted.names.error.DomainError as e:
-                    raise IOError(e)
-            elif twisted.internet.abstract.isIPAddress(resolved):
-                resolved_family = socket.AF_INET
-            elif twisted.internet.abstract.isIPv6Address(resolved):
-                resolved_family = socket.AF_INET6
-            else:
-                resolved_family = socket.AF_UNSPEC
-        if family != socket.AF_UNSPEC and family != resolved_family:
-            raise Exception('Requested socket family %d but got %d' %
-                            (family, resolved_family))
-        result = [
-            (resolved_family, (resolved, port)),
-        ]
-        raise gen.Return(result)
-
-
-if hasattr(gen.convert_yielded, 'register'):
-    @gen.convert_yielded.register(Deferred)  # type: ignore
-    def _(d):
-        f = Future()
-
-        def errback(failure):
-            try:
-                failure.raiseException()
-                # Should never happen, but just in case
-                raise Exception("errback called without error")
-            except:
-                f.set_exc_info(sys.exc_info())
-        d.addCallbacks(f.set_result, errback)
-        return f
+# Author: Ovidiu Predescu 
+# Date: July 2011 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+"""Bridges between the Twisted reactor and Tornado IOLoop. 
+ 
+This module lets you run applications and libraries written for 
+Twisted in a Tornado application.  It can be used in two modes, 
+depending on which library's underlying event loop you want to use. 
+ 
+This module has been tested with Twisted versions 11.0.0 and newer. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import datetime 
+import functools 
+import numbers 
+import socket 
+import sys 
+ 
+import twisted.internet.abstract  # type: ignore 
+from twisted.internet.defer import Deferred  # type: ignore 
+from twisted.internet.posixbase import PosixReactorBase  # type: ignore 
+from twisted.internet.interfaces import IReactorFDSet, IDelayedCall, IReactorTime, IReadDescriptor, IWriteDescriptor  # type: ignore 
+from twisted.python import failure, log  # type: ignore 
+from twisted.internet import error  # type: ignore 
+import twisted.names.cache  # type: ignore 
+import twisted.names.client  # type: ignore 
+import twisted.names.hosts  # type: ignore 
+import twisted.names.resolve  # type: ignore 
+ 
+from zope.interface import implementer  # type: ignore 
+ 
+from tornado.concurrent import Future 
+from tornado.escape import utf8 
+from tornado import gen 
+import tornado.ioloop 
+from tornado.log import app_log 
+from tornado.netutil import Resolver 
+from tornado.stack_context import NullContext, wrap 
+from tornado.ioloop import IOLoop 
+from tornado.util import timedelta_to_seconds 
+ 
+ 
+@implementer(IDelayedCall) 
+class TornadoDelayedCall(object): 
+    """DelayedCall object for Tornado.""" 
+    def __init__(self, reactor, seconds, f, *args, **kw): 
+        self._reactor = reactor 
+        self._func = functools.partial(f, *args, **kw) 
+        self._time = self._reactor.seconds() + seconds 
+        self._timeout = self._reactor._io_loop.add_timeout(self._time, 
+                                                           self._called) 
+        self._active = True 
+ 
+    def _called(self): 
+        self._active = False 
+        self._reactor._removeDelayedCall(self) 
+        try: 
+            self._func() 
+        except: 
+            app_log.error("_called caught exception", exc_info=True) 
+ 
+    def getTime(self): 
+        return self._time 
+ 
+    def cancel(self): 
+        self._active = False 
+        self._reactor._io_loop.remove_timeout(self._timeout) 
+        self._reactor._removeDelayedCall(self) 
+ 
+    def delay(self, seconds): 
+        self._reactor._io_loop.remove_timeout(self._timeout) 
+        self._time += seconds 
+        self._timeout = self._reactor._io_loop.add_timeout(self._time, 
+                                                           self._called) 
+ 
+    def reset(self, seconds): 
+        self._reactor._io_loop.remove_timeout(self._timeout) 
+        self._time = self._reactor.seconds() + seconds 
+        self._timeout = self._reactor._io_loop.add_timeout(self._time, 
+                                                           self._called) 
+ 
+    def active(self): 
+        return self._active 
+ 
+ 
+@implementer(IReactorTime, IReactorFDSet) 
+class TornadoReactor(PosixReactorBase): 
+    """Twisted reactor built on the Tornado IOLoop. 
+ 
+    `TornadoReactor` implements the Twisted reactor interface on top of 
+    the Tornado IOLoop.  To use it, simply call `install` at the beginning 
+    of the application:: 
+ 
+        import tornado.platform.twisted 
+        tornado.platform.twisted.install() 
+        from twisted.internet import reactor 
+ 
+    When the app is ready to start, call ``IOLoop.current().start()`` 
+    instead of ``reactor.run()``. 
+ 
+    It is also possible to create a non-global reactor by calling 
+    ``tornado.platform.twisted.TornadoReactor(io_loop)``.  However, if 
+    the `.IOLoop` and reactor are to be short-lived (such as those used in 
+    unit tests), additional cleanup may be required.  Specifically, it is 
+    recommended to call:: 
+ 
+        reactor.fireSystemEvent('shutdown') 
+        reactor.disconnectAll() 
+ 
+    before closing the `.IOLoop`. 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+    """ 
+    def __init__(self, io_loop=None): 
+        if not io_loop: 
+            io_loop = tornado.ioloop.IOLoop.current() 
+        self._io_loop = io_loop 
+        self._readers = {}  # map of reader objects to fd 
+        self._writers = {}  # map of writer objects to fd 
+        self._fds = {}  # a map of fd to a (reader, writer) tuple 
+        self._delayedCalls = {} 
+        PosixReactorBase.__init__(self) 
+        self.addSystemEventTrigger('during', 'shutdown', self.crash) 
+ 
+        # IOLoop.start() bypasses some of the reactor initialization. 
+        # Fire off the necessary events if they weren't already triggered 
+        # by reactor.run(). 
+        def start_if_necessary(): 
+            if not self._started: 
+                self.fireSystemEvent('startup') 
+        self._io_loop.add_callback(start_if_necessary) 
+ 
+    # IReactorTime 
+    def seconds(self): 
+        return self._io_loop.time() 
+ 
+    def callLater(self, seconds, f, *args, **kw): 
+        dc = TornadoDelayedCall(self, seconds, f, *args, **kw) 
+        self._delayedCalls[dc] = True 
+        return dc 
+ 
+    def getDelayedCalls(self): 
+        return [x for x in self._delayedCalls if x._active] 
+ 
+    def _removeDelayedCall(self, dc): 
+        if dc in self._delayedCalls: 
+            del self._delayedCalls[dc] 
+ 
+    # IReactorThreads 
+    def callFromThread(self, f, *args, **kw): 
+        assert callable(f), "%s is not callable" % f 
+        with NullContext(): 
+            # This NullContext is mainly for an edge case when running 
+            # TwistedIOLoop on top of a TornadoReactor. 
+            # TwistedIOLoop.add_callback uses reactor.callFromThread and 
+            # should not pick up additional StackContexts along the way. 
+            self._io_loop.add_callback(f, *args, **kw) 
+ 
+    # We don't need the waker code from the super class, Tornado uses 
+    # its own waker. 
+    def installWaker(self): 
+        pass 
+ 
+    def wakeUp(self): 
+        pass 
+ 
+    # IReactorFDSet 
+    def _invoke_callback(self, fd, events): 
+        if fd not in self._fds: 
+            return 
+        (reader, writer) = self._fds[fd] 
+        if reader: 
+            err = None 
+            if reader.fileno() == -1: 
+                err = error.ConnectionLost() 
+            elif events & IOLoop.READ: 
+                err = log.callWithLogger(reader, reader.doRead) 
+            if err is None and events & IOLoop.ERROR: 
+                err = error.ConnectionLost() 
+            if err is not None: 
+                self.removeReader(reader) 
+                reader.readConnectionLost(failure.Failure(err)) 
+        if writer: 
+            err = None 
+            if writer.fileno() == -1: 
+                err = error.ConnectionLost() 
+            elif events & IOLoop.WRITE: 
+                err = log.callWithLogger(writer, writer.doWrite) 
+            if err is None and events & IOLoop.ERROR: 
+                err = error.ConnectionLost() 
+            if err is not None: 
+                self.removeWriter(writer) 
+                writer.writeConnectionLost(failure.Failure(err)) 
+ 
+    def addReader(self, reader): 
+        if reader in self._readers: 
+            # Don't add the reader if it's already there 
+            return 
+        fd = reader.fileno() 
+        self._readers[reader] = fd 
+        if fd in self._fds: 
+            (_, writer) = self._fds[fd] 
+            self._fds[fd] = (reader, writer) 
+            if writer: 
+                # We already registered this fd for write events, 
+                # update it for read events as well. 
+                self._io_loop.update_handler(fd, IOLoop.READ | IOLoop.WRITE) 
+        else: 
+            with NullContext(): 
+                self._fds[fd] = (reader, None) 
+                self._io_loop.add_handler(fd, self._invoke_callback, 
+                                          IOLoop.READ) 
+ 
+    def addWriter(self, writer): 
+        if writer in self._writers: 
+            return 
+        fd = writer.fileno() 
+        self._writers[writer] = fd 
+        if fd in self._fds: 
+            (reader, _) = self._fds[fd] 
+            self._fds[fd] = (reader, writer) 
+            if reader: 
+                # We already registered this fd for read events, 
+                # update it for write events as well. 
+                self._io_loop.update_handler(fd, IOLoop.READ | IOLoop.WRITE) 
+        else: 
+            with NullContext(): 
+                self._fds[fd] = (None, writer) 
+                self._io_loop.add_handler(fd, self._invoke_callback, 
+                                          IOLoop.WRITE) 
+ 
+    def removeReader(self, reader): 
+        if reader in self._readers: 
+            fd = self._readers.pop(reader) 
+            (_, writer) = self._fds[fd] 
+            if writer: 
+                # We have a writer so we need to update the IOLoop for 
+                # write events only. 
+                self._fds[fd] = (None, writer) 
+                self._io_loop.update_handler(fd, IOLoop.WRITE) 
+            else: 
+                # Since we have no writer registered, we remove the 
+                # entry from _fds and unregister the handler from the 
+                # IOLoop 
+                del self._fds[fd] 
+                self._io_loop.remove_handler(fd) 
+ 
+    def removeWriter(self, writer): 
+        if writer in self._writers: 
+            fd = self._writers.pop(writer) 
+            (reader, _) = self._fds[fd] 
+            if reader: 
+                # We have a reader so we need to update the IOLoop for 
+                # read events only. 
+                self._fds[fd] = (reader, None) 
+                self._io_loop.update_handler(fd, IOLoop.READ) 
+            else: 
+                # Since we have no reader registered, we remove the 
+                # entry from the _fds and unregister the handler from 
+                # the IOLoop. 
+                del self._fds[fd] 
+                self._io_loop.remove_handler(fd) 
+ 
+    def removeAll(self): 
+        return self._removeAll(self._readers, self._writers) 
+ 
+    def getReaders(self): 
+        return self._readers.keys() 
+ 
+    def getWriters(self): 
+        return self._writers.keys() 
+ 
+    # The following functions are mainly used in twisted-style test cases; 
+    # it is expected that most users of the TornadoReactor will call 
+    # IOLoop.start() instead of Reactor.run(). 
+    def stop(self): 
+        PosixReactorBase.stop(self) 
+        fire_shutdown = functools.partial(self.fireSystemEvent, "shutdown") 
+        self._io_loop.add_callback(fire_shutdown) 
+ 
+    def crash(self): 
+        PosixReactorBase.crash(self) 
+        self._io_loop.stop() 
+ 
+    def doIteration(self, delay): 
+        raise NotImplementedError("doIteration") 
+ 
+    def mainLoop(self): 
+        # Since this class is intended to be used in applications 
+        # where the top-level event loop is ``io_loop.start()`` rather 
+        # than ``reactor.run()``, it is implemented a little 
+        # differently than other Twisted reactors. We override 
+        # ``mainLoop`` instead of ``doIteration`` and must implement 
+        # timed call functionality on top of `.IOLoop.add_timeout` 
+        # rather than using the implementation in 
+        # ``PosixReactorBase``. 
+        self._io_loop.start() 
+ 
+ 
+class _TestReactor(TornadoReactor): 
+    """Subclass of TornadoReactor for use in unittests. 
+ 
+    This can't go in the test.py file because of import-order dependencies 
+    with the Twisted reactor test builder. 
+    """ 
+    def __init__(self): 
+        # always use a new ioloop 
+        super(_TestReactor, self).__init__(IOLoop()) 
+ 
+    def listenTCP(self, port, factory, backlog=50, interface=''): 
+        # default to localhost to avoid firewall prompts on the mac 
+        if not interface: 
+            interface = '127.0.0.1' 
+        return super(_TestReactor, self).listenTCP( 
+            port, factory, backlog=backlog, interface=interface) 
+ 
+    def listenUDP(self, port, protocol, interface='', maxPacketSize=8192): 
+        if not interface: 
+            interface = '127.0.0.1' 
+        return super(_TestReactor, self).listenUDP( 
+            port, protocol, interface=interface, maxPacketSize=maxPacketSize) 
+ 
+ 
+def install(io_loop=None): 
+    """Install this package as the default Twisted reactor. 
+ 
+    ``install()`` must be called very early in the startup process, 
+    before most other twisted-related imports. Conversely, because it 
+    initializes the `.IOLoop`, it cannot be called before 
+    `.fork_processes` or multi-process `~.TCPServer.start`. These 
+    conflicting requirements make it difficult to use `.TornadoReactor` 
+    in multi-process mode, and an external process manager such as 
+    ``supervisord`` is recommended instead. 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+ 
+    """ 
+    if not io_loop: 
+        io_loop = tornado.ioloop.IOLoop.current() 
+    reactor = TornadoReactor(io_loop) 
+    from twisted.internet.main import installReactor  # type: ignore 
+    installReactor(reactor) 
+    return reactor 
+ 
+ 
+@implementer(IReadDescriptor, IWriteDescriptor) 
+class _FD(object): 
+    def __init__(self, fd, fileobj, handler): 
+        self.fd = fd 
+        self.fileobj = fileobj 
+        self.handler = handler 
+        self.reading = False 
+        self.writing = False 
+        self.lost = False 
+ 
+    def fileno(self): 
+        return self.fd 
+ 
+    def doRead(self): 
+        if not self.lost: 
+            self.handler(self.fileobj, tornado.ioloop.IOLoop.READ) 
+ 
+    def doWrite(self): 
+        if not self.lost: 
+            self.handler(self.fileobj, tornado.ioloop.IOLoop.WRITE) 
+ 
+    def connectionLost(self, reason): 
+        if not self.lost: 
+            self.handler(self.fileobj, tornado.ioloop.IOLoop.ERROR) 
+            self.lost = True 
+ 
+    def logPrefix(self): 
+        return '' 
+ 
+ 
+class TwistedIOLoop(tornado.ioloop.IOLoop): 
+    """IOLoop implementation that runs on Twisted. 
+ 
+    `TwistedIOLoop` implements the Tornado IOLoop interface on top of 
+    the Twisted reactor. Recommended usage:: 
+ 
+        from tornado.platform.twisted import TwistedIOLoop 
+        from twisted.internet import reactor 
+        TwistedIOLoop().install() 
+        # Set up your tornado application as usual using `IOLoop.instance` 
+        reactor.run() 
+ 
+    Uses the global Twisted reactor by default.  To create multiple 
+    ``TwistedIOLoops`` in the same process, you must pass a unique reactor 
+    when constructing each one. 
+ 
+    Not compatible with `tornado.process.Subprocess.set_exit_callback` 
+    because the ``SIGCHLD`` handlers used by Tornado and Twisted conflict 
+    with each other. 
+ 
+    See also :meth:`tornado.ioloop.IOLoop.install` for general notes on 
+    installing alternative IOLoops. 
+    """ 
+    def initialize(self, reactor=None, **kwargs): 
+        super(TwistedIOLoop, self).initialize(**kwargs) 
+        if reactor is None: 
+            import twisted.internet.reactor  # type: ignore 
+            reactor = twisted.internet.reactor 
+        self.reactor = reactor 
+        self.fds = {} 
+ 
+    def close(self, all_fds=False): 
+        fds = self.fds 
+        self.reactor.removeAll() 
+        for c in self.reactor.getDelayedCalls(): 
+            c.cancel() 
+        if all_fds: 
+            for fd in fds.values(): 
+                self.close_fd(fd.fileobj) 
+ 
+    def add_handler(self, fd, handler, events): 
+        if fd in self.fds: 
+            raise ValueError('fd %s added twice' % fd) 
+        fd, fileobj = self.split_fd(fd) 
+        self.fds[fd] = _FD(fd, fileobj, wrap(handler)) 
+        if events & tornado.ioloop.IOLoop.READ: 
+            self.fds[fd].reading = True 
+            self.reactor.addReader(self.fds[fd]) 
+        if events & tornado.ioloop.IOLoop.WRITE: 
+            self.fds[fd].writing = True 
+            self.reactor.addWriter(self.fds[fd]) 
+ 
+    def update_handler(self, fd, events): 
+        fd, fileobj = self.split_fd(fd) 
+        if events & tornado.ioloop.IOLoop.READ: 
+            if not self.fds[fd].reading: 
+                self.fds[fd].reading = True 
+                self.reactor.addReader(self.fds[fd]) 
+        else: 
+            if self.fds[fd].reading: 
+                self.fds[fd].reading = False 
+                self.reactor.removeReader(self.fds[fd]) 
+        if events & tornado.ioloop.IOLoop.WRITE: 
+            if not self.fds[fd].writing: 
+                self.fds[fd].writing = True 
+                self.reactor.addWriter(self.fds[fd]) 
+        else: 
+            if self.fds[fd].writing: 
+                self.fds[fd].writing = False 
+                self.reactor.removeWriter(self.fds[fd]) 
+ 
+    def remove_handler(self, fd): 
+        fd, fileobj = self.split_fd(fd) 
+        if fd not in self.fds: 
+            return 
+        self.fds[fd].lost = True 
+        if self.fds[fd].reading: 
+            self.reactor.removeReader(self.fds[fd]) 
+        if self.fds[fd].writing: 
+            self.reactor.removeWriter(self.fds[fd]) 
+        del self.fds[fd] 
+ 
+    def start(self): 
+        old_current = IOLoop.current(instance=False) 
+        try: 
+            self._setup_logging() 
+            self.make_current() 
+            self.reactor.run() 
+        finally: 
+            if old_current is None: 
+                IOLoop.clear_current() 
+            else: 
+                old_current.make_current() 
+ 
+    def stop(self): 
+        self.reactor.crash() 
+ 
+    def add_timeout(self, deadline, callback, *args, **kwargs): 
+        # This method could be simplified (since tornado 4.0) by 
+        # overriding call_at instead of add_timeout, but we leave it 
+        # for now as a test of backwards-compatibility. 
+        if isinstance(deadline, numbers.Real): 
+            delay = max(deadline - self.time(), 0) 
+        elif isinstance(deadline, datetime.timedelta): 
+            delay = timedelta_to_seconds(deadline) 
+        else: 
+            raise TypeError("Unsupported deadline %r") 
+        return self.reactor.callLater( 
+            delay, self._run_callback, 
+            functools.partial(wrap(callback), *args, **kwargs)) 
+ 
+    def remove_timeout(self, timeout): 
+        if timeout.active(): 
+            timeout.cancel() 
+ 
+    def add_callback(self, callback, *args, **kwargs): 
+        self.reactor.callFromThread( 
+            self._run_callback, 
+            functools.partial(wrap(callback), *args, **kwargs)) 
+ 
+    def add_callback_from_signal(self, callback, *args, **kwargs): 
+        self.add_callback(callback, *args, **kwargs) 
+ 
+ 
+class TwistedResolver(Resolver): 
+    """Twisted-based asynchronous resolver. 
+ 
+    This is a non-blocking and non-threaded resolver.  It is 
+    recommended only when threads cannot be used, since it has 
+    limitations compared to the standard ``getaddrinfo``-based 
+    `~tornado.netutil.Resolver` and 
+    `~tornado.netutil.ThreadedResolver`.  Specifically, it returns at 
+    most one result, and arguments other than ``host`` and ``family`` 
+    are ignored.  It may fail to resolve when ``family`` is not 
+    ``socket.AF_UNSPEC``. 
+ 
+    Requires Twisted 12.1 or newer. 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+    """ 
+    def initialize(self, io_loop=None): 
+        self.io_loop = io_loop or IOLoop.current() 
+        # partial copy of twisted.names.client.createResolver, which doesn't 
+        # allow for a reactor to be passed in. 
+        self.reactor = tornado.platform.twisted.TornadoReactor(io_loop) 
+ 
+        host_resolver = twisted.names.hosts.Resolver('/etc/hosts') 
+        cache_resolver = twisted.names.cache.CacheResolver(reactor=self.reactor) 
+        real_resolver = twisted.names.client.Resolver('/etc/resolv.conf', 
+                                                      reactor=self.reactor) 
+        self.resolver = twisted.names.resolve.ResolverChain( 
+            [host_resolver, cache_resolver, real_resolver]) 
+ 
+    @gen.coroutine 
+    def resolve(self, host, port, family=0): 
+        # getHostByName doesn't accept IP addresses, so if the input 
+        # looks like an IP address just return it immediately. 
+        if twisted.internet.abstract.isIPAddress(host): 
+            resolved = host 
+            resolved_family = socket.AF_INET 
+        elif twisted.internet.abstract.isIPv6Address(host): 
+            resolved = host 
+            resolved_family = socket.AF_INET6 
+        else: 
+            deferred = self.resolver.getHostByName(utf8(host)) 
+            resolved = yield gen.Task(deferred.addBoth) 
+            if isinstance(resolved, failure.Failure): 
+                try: 
+                    resolved.raiseException() 
+                except twisted.names.error.DomainError as e: 
+                    raise IOError(e) 
+            elif twisted.internet.abstract.isIPAddress(resolved): 
+                resolved_family = socket.AF_INET 
+            elif twisted.internet.abstract.isIPv6Address(resolved): 
+                resolved_family = socket.AF_INET6 
+            else: 
+                resolved_family = socket.AF_UNSPEC 
+        if family != socket.AF_UNSPEC and family != resolved_family: 
+            raise Exception('Requested socket family %d but got %d' % 
+                            (family, resolved_family)) 
+        result = [ 
+            (resolved_family, (resolved, port)), 
+        ] 
+        raise gen.Return(result) 
+ 
+ 
+if hasattr(gen.convert_yielded, 'register'): 
+    @gen.convert_yielded.register(Deferred)  # type: ignore 
+    def _(d): 
+        f = Future() 
+ 
+        def errback(failure): 
+            try: 
+                failure.raiseException() 
+                # Should never happen, but just in case 
+                raise Exception("errback called without error") 
+            except: 
+                f.set_exc_info(sys.exc_info()) 
+        d.addCallbacks(f.set_result, errback) 
+        return f 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/windows.py b/contrib/python/tornado/tornado-4/tornado/platform/windows.py
index e94a0cf13d..5e223c8191 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/windows.py
+++ b/contrib/python/tornado/tornado-4/tornado/platform/windows.py
@@ -1,20 +1,20 @@
-# NOTE: win32 support is currently experimental, and not recommended
-# for production use.
-
-
-from __future__ import absolute_import, division, print_function
-import ctypes  # type: ignore
-import ctypes.wintypes  # type: ignore
-
-# See: http://msdn.microsoft.com/en-us/library/ms724935(VS.85).aspx
-SetHandleInformation = ctypes.windll.kernel32.SetHandleInformation
-SetHandleInformation.argtypes = (ctypes.wintypes.HANDLE, ctypes.wintypes.DWORD, ctypes.wintypes.DWORD)
-SetHandleInformation.restype = ctypes.wintypes.BOOL
-
-HANDLE_FLAG_INHERIT = 0x00000001
-
-
-def set_close_exec(fd):
-    success = SetHandleInformation(fd, HANDLE_FLAG_INHERIT, 0)
-    if not success:
-        raise ctypes.WinError()
+# NOTE: win32 support is currently experimental, and not recommended 
+# for production use. 
+ 
+ 
+from __future__ import absolute_import, division, print_function 
+import ctypes  # type: ignore 
+import ctypes.wintypes  # type: ignore 
+ 
+# See: http://msdn.microsoft.com/en-us/library/ms724935(VS.85).aspx 
+SetHandleInformation = ctypes.windll.kernel32.SetHandleInformation 
+SetHandleInformation.argtypes = (ctypes.wintypes.HANDLE, ctypes.wintypes.DWORD, ctypes.wintypes.DWORD) 
+SetHandleInformation.restype = ctypes.wintypes.BOOL 
+ 
+HANDLE_FLAG_INHERIT = 0x00000001 
+ 
+ 
+def set_close_exec(fd): 
+    success = SetHandleInformation(fd, HANDLE_FLAG_INHERIT, 0) 
+    if not success: 
+        raise ctypes.WinError() 
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/ya.make b/contrib/python/tornado/tornado-4/tornado/platform/ya.make
index 195c1fad93..c960eea835 100644
--- a/contrib/python/tornado/tornado-4/tornado/platform/ya.make
+++ b/contrib/python/tornado/tornado-4/tornado/platform/ya.make
@@ -1 +1 @@
-OWNER(g:python-contrib)
+OWNER(g:python-contrib) 
diff --git a/contrib/python/tornado/tornado-4/tornado/process.py b/contrib/python/tornado/tornado-4/tornado/process.py
index fae94f3c13..8bf8818c1a 100644
--- a/contrib/python/tornado/tornado-4/tornado/process.py
+++ b/contrib/python/tornado/tornado-4/tornado/process.py
@@ -1,365 +1,365 @@
-#!/usr/bin/env python
-#
-# Copyright 2011 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Utilities for working with multiple processes, including both forking
-the server into multiple processes and managing subprocesses.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import errno
-import os
-import signal
-import subprocess
-import sys
-import time
-
-from binascii import hexlify
-
-from tornado.concurrent import Future
-from tornado import ioloop
-from tornado.iostream import PipeIOStream
-from tornado.log import gen_log
-from tornado.platform.auto import set_close_exec
-from tornado import stack_context
-from tornado.util import errno_from_exception, PY3
-
-try:
-    import multiprocessing
-except ImportError:
-    # Multiprocessing is not available on Google App Engine.
-    multiprocessing = None
-
-if PY3:
-    long = int
-
-# Re-export this exception for convenience.
-try:
-    CalledProcessError = subprocess.CalledProcessError
-except AttributeError:
-    # The subprocess module exists in Google App Engine, but is empty.
-    # This module isn't very useful in that case, but it should
-    # at least be importable.
-    if 'APPENGINE_RUNTIME' not in os.environ:
-        raise
-
-
-def cpu_count():
-    """Returns the number of processors on this machine."""
-    if multiprocessing is None:
-        return 1
-    try:
-        return multiprocessing.cpu_count()
-    except NotImplementedError:
-        pass
-    try:
-        return os.sysconf("SC_NPROCESSORS_CONF")
-    except (AttributeError, ValueError):
-        pass
-    gen_log.error("Could not detect number of processors; assuming 1")
-    return 1
-
-
-def _reseed_random():
-    if 'random' not in sys.modules:
-        return
-    import random
-    # If os.urandom is available, this method does the same thing as
-    # random.seed (at least as of python 2.6).  If os.urandom is not
-    # available, we mix in the pid in addition to a timestamp.
-    try:
-        seed = long(hexlify(os.urandom(16)), 16)
-    except NotImplementedError:
-        seed = int(time.time() * 1000) ^ os.getpid()
-    random.seed(seed)
-
-
-def _pipe_cloexec():
-    r, w = os.pipe()
-    set_close_exec(r)
-    set_close_exec(w)
-    return r, w
-
-
-_task_id = None
-
-
-def fork_processes(num_processes, max_restarts=100):
-    """Starts multiple worker processes.
-
-    If ``num_processes`` is None or <= 0, we detect the number of cores
-    available on this machine and fork that number of child
-    processes. If ``num_processes`` is given and > 0, we fork that
-    specific number of sub-processes.
-
-    Since we use processes and not threads, there is no shared memory
-    between any server code.
-
-    Note that multiple processes are not compatible with the autoreload
-    module (or the ``autoreload=True`` option to `tornado.web.Application`
-    which defaults to True when ``debug=True``).
-    When using multiple processes, no IOLoops can be created or
-    referenced until after the call to ``fork_processes``.
-
-    In each child process, ``fork_processes`` returns its *task id*, a
-    number between 0 and ``num_processes``.  Processes that exit
-    abnormally (due to a signal or non-zero exit status) are restarted
-    with the same id (up to ``max_restarts`` times).  In the parent
-    process, ``fork_processes`` returns None if all child processes
-    have exited normally, but will otherwise only exit by throwing an
-    exception.
-    """
-    global _task_id
-    assert _task_id is None
-    if num_processes is None or num_processes <= 0:
-        num_processes = cpu_count()
-    if ioloop.IOLoop.initialized():
-        raise RuntimeError("Cannot run in multiple processes: IOLoop instance "
-                           "has already been initialized. You cannot call "
-                           "IOLoop.instance() before calling start_processes()")
-    gen_log.info("Starting %d processes", num_processes)
-    children = {}
-
-    def start_child(i):
-        pid = os.fork()
-        if pid == 0:
-            # child process
-            _reseed_random()
-            global _task_id
-            _task_id = i
-            return i
-        else:
-            children[pid] = i
-            return None
-
-    for i in range(num_processes):
-        id = start_child(i)
-        if id is not None:
-            return id
-    num_restarts = 0
-    while children:
-        try:
-            pid, status = os.wait()
-        except OSError as e:
-            if errno_from_exception(e) == errno.EINTR:
-                continue
-            raise
-        if pid not in children:
-            continue
-        id = children.pop(pid)
-        if os.WIFSIGNALED(status):
-            gen_log.warning("child %d (pid %d) killed by signal %d, restarting",
-                            id, pid, os.WTERMSIG(status))
-        elif os.WEXITSTATUS(status) != 0:
-            gen_log.warning("child %d (pid %d) exited with status %d, restarting",
-                            id, pid, os.WEXITSTATUS(status))
-        else:
-            gen_log.info("child %d (pid %d) exited normally", id, pid)
-            continue
-        num_restarts += 1
-        if num_restarts > max_restarts:
-            raise RuntimeError("Too many child restarts, giving up")
-        new_id = start_child(id)
-        if new_id is not None:
-            return new_id
-    # All child processes exited cleanly, so exit the master process
-    # instead of just returning to right after the call to
-    # fork_processes (which will probably just start up another IOLoop
-    # unless the caller checks the return value).
-    sys.exit(0)
-
-
-def task_id():
-    """Returns the current task id, if any.
-
-    Returns None if this process was not created by `fork_processes`.
-    """
-    global _task_id
-    return _task_id
-
-
-class Subprocess(object):
-    """Wraps ``subprocess.Popen`` with IOStream support.
-
-    The constructor is the same as ``subprocess.Popen`` with the following
-    additions:
-
-    * ``stdin``, ``stdout``, and ``stderr`` may have the value
-      ``tornado.process.Subprocess.STREAM``, which will make the corresponding
-      attribute of the resulting Subprocess a `.PipeIOStream`.
-    * A new keyword argument ``io_loop`` may be used to pass in an IOLoop.
-
-    The ``Subprocess.STREAM`` option and the ``set_exit_callback`` and
-    ``wait_for_exit`` methods do not work on Windows. There is
-    therefore no reason to use this class instead of
-    ``subprocess.Popen`` on that platform.
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-
-    """
-    STREAM = object()
-
-    _initialized = False
-    _waiting = {}  # type: ignore
-
-    def __init__(self, *args, **kwargs):
-        self.io_loop = kwargs.pop('io_loop', None) or ioloop.IOLoop.current()
-        # All FDs we create should be closed on error; those in to_close
-        # should be closed in the parent process on success.
-        pipe_fds = []
-        to_close = []
-        if kwargs.get('stdin') is Subprocess.STREAM:
-            in_r, in_w = _pipe_cloexec()
-            kwargs['stdin'] = in_r
-            pipe_fds.extend((in_r, in_w))
-            to_close.append(in_r)
-            self.stdin = PipeIOStream(in_w, io_loop=self.io_loop)
-        if kwargs.get('stdout') is Subprocess.STREAM:
-            out_r, out_w = _pipe_cloexec()
-            kwargs['stdout'] = out_w
-            pipe_fds.extend((out_r, out_w))
-            to_close.append(out_w)
-            self.stdout = PipeIOStream(out_r, io_loop=self.io_loop)
-        if kwargs.get('stderr') is Subprocess.STREAM:
-            err_r, err_w = _pipe_cloexec()
-            kwargs['stderr'] = err_w
-            pipe_fds.extend((err_r, err_w))
-            to_close.append(err_w)
-            self.stderr = PipeIOStream(err_r, io_loop=self.io_loop)
-        try:
-            self.proc = subprocess.Popen(*args, **kwargs)
-        except:
-            for fd in pipe_fds:
-                os.close(fd)
-            raise
-        for fd in to_close:
-            os.close(fd)
-        for attr in ['stdin', 'stdout', 'stderr', 'pid']:
-            if not hasattr(self, attr):  # don't clobber streams set above
-                setattr(self, attr, getattr(self.proc, attr))
-        self._exit_callback = None
-        self.returncode = None
-
-    def set_exit_callback(self, callback):
-        """Runs ``callback`` when this process exits.
-
-        The callback takes one argument, the return code of the process.
-
-        This method uses a ``SIGCHLD`` handler, which is a global setting
-        and may conflict if you have other libraries trying to handle the
-        same signal.  If you are using more than one ``IOLoop`` it may
-        be necessary to call `Subprocess.initialize` first to designate
-        one ``IOLoop`` to run the signal handlers.
-
-        In many cases a close callback on the stdout or stderr streams
-        can be used as an alternative to an exit callback if the
-        signal handler is causing a problem.
-        """
-        self._exit_callback = stack_context.wrap(callback)
-        Subprocess.initialize(self.io_loop)
-        Subprocess._waiting[self.pid] = self
-        Subprocess._try_cleanup_process(self.pid)
-
-    def wait_for_exit(self, raise_error=True):
-        """Returns a `.Future` which resolves when the process exits.
-
-        Usage::
-
-            ret = yield proc.wait_for_exit()
-
-        This is a coroutine-friendly alternative to `set_exit_callback`
-        (and a replacement for the blocking `subprocess.Popen.wait`).
-
-        By default, raises `subprocess.CalledProcessError` if the process
-        has a non-zero exit status. Use ``wait_for_exit(raise_error=False)``
-        to suppress this behavior and return the exit status without raising.
-
-        .. versionadded:: 4.2
-        """
-        future = Future()
-
-        def callback(ret):
-            if ret != 0 and raise_error:
-                # Unfortunately we don't have the original args any more.
-                future.set_exception(CalledProcessError(ret, None))
-            else:
-                future.set_result(ret)
-        self.set_exit_callback(callback)
-        return future
-
-    @classmethod
-    def initialize(cls, io_loop=None):
-        """Initializes the ``SIGCHLD`` handler.
-
-        The signal handler is run on an `.IOLoop` to avoid locking issues.
-        Note that the `.IOLoop` used for signal handling need not be the
-        same one used by individual Subprocess objects (as long as the
-        ``IOLoops`` are each running in separate threads).
-
-        .. versionchanged:: 4.1
-           The ``io_loop`` argument is deprecated.
-        """
-        if cls._initialized:
-            return
-        if io_loop is None:
-            io_loop = ioloop.IOLoop.current()
-        cls._old_sigchld = signal.signal(
-            signal.SIGCHLD,
-            lambda sig, frame: io_loop.add_callback_from_signal(cls._cleanup))
-        cls._initialized = True
-
-    @classmethod
-    def uninitialize(cls):
-        """Removes the ``SIGCHLD`` handler."""
-        if not cls._initialized:
-            return
-        signal.signal(signal.SIGCHLD, cls._old_sigchld)
-        cls._initialized = False
-
-    @classmethod
-    def _cleanup(cls):
-        for pid in list(cls._waiting.keys()):  # make a copy
-            cls._try_cleanup_process(pid)
-
-    @classmethod
-    def _try_cleanup_process(cls, pid):
-        try:
-            ret_pid, status = os.waitpid(pid, os.WNOHANG)
-        except OSError as e:
-            if errno_from_exception(e) == errno.ECHILD:
-                return
-        if ret_pid == 0:
-            return
-        assert ret_pid == pid
-        subproc = cls._waiting.pop(pid)
-        subproc.io_loop.add_callback_from_signal(
-            subproc._set_returncode, status)
-
-    def _set_returncode(self, status):
-        if os.WIFSIGNALED(status):
-            self.returncode = -os.WTERMSIG(status)
-        else:
-            assert os.WIFEXITED(status)
-            self.returncode = os.WEXITSTATUS(status)
-        # We've taken over wait() duty from the subprocess.Popen
-        # object. If we don't inform it of the process's return code,
-        # it will log a warning at destruction in python 3.6+.
-        self.proc.returncode = self.returncode
-        if self._exit_callback:
-            callback = self._exit_callback
-            self._exit_callback = None
-            callback(self.returncode)
+#!/usr/bin/env python 
+# 
+# Copyright 2011 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Utilities for working with multiple processes, including both forking 
+the server into multiple processes and managing subprocesses. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import errno 
+import os 
+import signal 
+import subprocess 
+import sys 
+import time 
+ 
+from binascii import hexlify 
+ 
+from tornado.concurrent import Future 
+from tornado import ioloop 
+from tornado.iostream import PipeIOStream 
+from tornado.log import gen_log 
+from tornado.platform.auto import set_close_exec 
+from tornado import stack_context 
+from tornado.util import errno_from_exception, PY3 
+ 
+try: 
+    import multiprocessing 
+except ImportError: 
+    # Multiprocessing is not available on Google App Engine. 
+    multiprocessing = None 
+ 
+if PY3: 
+    long = int 
+ 
+# Re-export this exception for convenience. 
+try: 
+    CalledProcessError = subprocess.CalledProcessError 
+except AttributeError: 
+    # The subprocess module exists in Google App Engine, but is empty. 
+    # This module isn't very useful in that case, but it should 
+    # at least be importable. 
+    if 'APPENGINE_RUNTIME' not in os.environ: 
+        raise 
+ 
+ 
+def cpu_count(): 
+    """Returns the number of processors on this machine.""" 
+    if multiprocessing is None: 
+        return 1 
+    try: 
+        return multiprocessing.cpu_count() 
+    except NotImplementedError: 
+        pass 
+    try: 
+        return os.sysconf("SC_NPROCESSORS_CONF") 
+    except (AttributeError, ValueError): 
+        pass 
+    gen_log.error("Could not detect number of processors; assuming 1") 
+    return 1 
+ 
+ 
+def _reseed_random(): 
+    if 'random' not in sys.modules: 
+        return 
+    import random 
+    # If os.urandom is available, this method does the same thing as 
+    # random.seed (at least as of python 2.6).  If os.urandom is not 
+    # available, we mix in the pid in addition to a timestamp. 
+    try: 
+        seed = long(hexlify(os.urandom(16)), 16) 
+    except NotImplementedError: 
+        seed = int(time.time() * 1000) ^ os.getpid() 
+    random.seed(seed) 
+ 
+ 
+def _pipe_cloexec(): 
+    r, w = os.pipe() 
+    set_close_exec(r) 
+    set_close_exec(w) 
+    return r, w 
+ 
+ 
+_task_id = None 
+ 
+ 
+def fork_processes(num_processes, max_restarts=100): 
+    """Starts multiple worker processes. 
+ 
+    If ``num_processes`` is None or <= 0, we detect the number of cores 
+    available on this machine and fork that number of child 
+    processes. If ``num_processes`` is given and > 0, we fork that 
+    specific number of sub-processes. 
+ 
+    Since we use processes and not threads, there is no shared memory 
+    between any server code. 
+ 
+    Note that multiple processes are not compatible with the autoreload 
+    module (or the ``autoreload=True`` option to `tornado.web.Application` 
+    which defaults to True when ``debug=True``). 
+    When using multiple processes, no IOLoops can be created or 
+    referenced until after the call to ``fork_processes``. 
+ 
+    In each child process, ``fork_processes`` returns its *task id*, a 
+    number between 0 and ``num_processes``.  Processes that exit 
+    abnormally (due to a signal or non-zero exit status) are restarted 
+    with the same id (up to ``max_restarts`` times).  In the parent 
+    process, ``fork_processes`` returns None if all child processes 
+    have exited normally, but will otherwise only exit by throwing an 
+    exception. 
+    """ 
+    global _task_id 
+    assert _task_id is None 
+    if num_processes is None or num_processes <= 0: 
+        num_processes = cpu_count() 
+    if ioloop.IOLoop.initialized(): 
+        raise RuntimeError("Cannot run in multiple processes: IOLoop instance " 
+                           "has already been initialized. You cannot call " 
+                           "IOLoop.instance() before calling start_processes()") 
+    gen_log.info("Starting %d processes", num_processes) 
+    children = {} 
+ 
+    def start_child(i): 
+        pid = os.fork() 
+        if pid == 0: 
+            # child process 
+            _reseed_random() 
+            global _task_id 
+            _task_id = i 
+            return i 
+        else: 
+            children[pid] = i 
+            return None 
+ 
+    for i in range(num_processes): 
+        id = start_child(i) 
+        if id is not None: 
+            return id 
+    num_restarts = 0 
+    while children: 
+        try: 
+            pid, status = os.wait() 
+        except OSError as e: 
+            if errno_from_exception(e) == errno.EINTR: 
+                continue 
+            raise 
+        if pid not in children: 
+            continue 
+        id = children.pop(pid) 
+        if os.WIFSIGNALED(status): 
+            gen_log.warning("child %d (pid %d) killed by signal %d, restarting", 
+                            id, pid, os.WTERMSIG(status)) 
+        elif os.WEXITSTATUS(status) != 0: 
+            gen_log.warning("child %d (pid %d) exited with status %d, restarting", 
+                            id, pid, os.WEXITSTATUS(status)) 
+        else: 
+            gen_log.info("child %d (pid %d) exited normally", id, pid) 
+            continue 
+        num_restarts += 1 
+        if num_restarts > max_restarts: 
+            raise RuntimeError("Too many child restarts, giving up") 
+        new_id = start_child(id) 
+        if new_id is not None: 
+            return new_id 
+    # All child processes exited cleanly, so exit the master process 
+    # instead of just returning to right after the call to 
+    # fork_processes (which will probably just start up another IOLoop 
+    # unless the caller checks the return value). 
+    sys.exit(0) 
+ 
+ 
+def task_id(): 
+    """Returns the current task id, if any. 
+ 
+    Returns None if this process was not created by `fork_processes`. 
+    """ 
+    global _task_id 
+    return _task_id 
+ 
+ 
+class Subprocess(object): 
+    """Wraps ``subprocess.Popen`` with IOStream support. 
+ 
+    The constructor is the same as ``subprocess.Popen`` with the following 
+    additions: 
+ 
+    * ``stdin``, ``stdout``, and ``stderr`` may have the value 
+      ``tornado.process.Subprocess.STREAM``, which will make the corresponding 
+      attribute of the resulting Subprocess a `.PipeIOStream`. 
+    * A new keyword argument ``io_loop`` may be used to pass in an IOLoop. 
+ 
+    The ``Subprocess.STREAM`` option and the ``set_exit_callback`` and 
+    ``wait_for_exit`` methods do not work on Windows. There is 
+    therefore no reason to use this class instead of 
+    ``subprocess.Popen`` on that platform. 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+ 
+    """ 
+    STREAM = object() 
+ 
+    _initialized = False 
+    _waiting = {}  # type: ignore 
+ 
+    def __init__(self, *args, **kwargs): 
+        self.io_loop = kwargs.pop('io_loop', None) or ioloop.IOLoop.current() 
+        # All FDs we create should be closed on error; those in to_close 
+        # should be closed in the parent process on success. 
+        pipe_fds = [] 
+        to_close = [] 
+        if kwargs.get('stdin') is Subprocess.STREAM: 
+            in_r, in_w = _pipe_cloexec() 
+            kwargs['stdin'] = in_r 
+            pipe_fds.extend((in_r, in_w)) 
+            to_close.append(in_r) 
+            self.stdin = PipeIOStream(in_w, io_loop=self.io_loop) 
+        if kwargs.get('stdout') is Subprocess.STREAM: 
+            out_r, out_w = _pipe_cloexec() 
+            kwargs['stdout'] = out_w 
+            pipe_fds.extend((out_r, out_w)) 
+            to_close.append(out_w) 
+            self.stdout = PipeIOStream(out_r, io_loop=self.io_loop) 
+        if kwargs.get('stderr') is Subprocess.STREAM: 
+            err_r, err_w = _pipe_cloexec() 
+            kwargs['stderr'] = err_w 
+            pipe_fds.extend((err_r, err_w)) 
+            to_close.append(err_w) 
+            self.stderr = PipeIOStream(err_r, io_loop=self.io_loop) 
+        try: 
+            self.proc = subprocess.Popen(*args, **kwargs) 
+        except: 
+            for fd in pipe_fds: 
+                os.close(fd) 
+            raise 
+        for fd in to_close: 
+            os.close(fd) 
+        for attr in ['stdin', 'stdout', 'stderr', 'pid']: 
+            if not hasattr(self, attr):  # don't clobber streams set above 
+                setattr(self, attr, getattr(self.proc, attr)) 
+        self._exit_callback = None 
+        self.returncode = None 
+ 
+    def set_exit_callback(self, callback): 
+        """Runs ``callback`` when this process exits. 
+ 
+        The callback takes one argument, the return code of the process. 
+ 
+        This method uses a ``SIGCHLD`` handler, which is a global setting 
+        and may conflict if you have other libraries trying to handle the 
+        same signal.  If you are using more than one ``IOLoop`` it may 
+        be necessary to call `Subprocess.initialize` first to designate 
+        one ``IOLoop`` to run the signal handlers. 
+ 
+        In many cases a close callback on the stdout or stderr streams 
+        can be used as an alternative to an exit callback if the 
+        signal handler is causing a problem. 
+        """ 
+        self._exit_callback = stack_context.wrap(callback) 
+        Subprocess.initialize(self.io_loop) 
+        Subprocess._waiting[self.pid] = self 
+        Subprocess._try_cleanup_process(self.pid) 
+ 
+    def wait_for_exit(self, raise_error=True): 
+        """Returns a `.Future` which resolves when the process exits. 
+ 
+        Usage:: 
+ 
+            ret = yield proc.wait_for_exit() 
+ 
+        This is a coroutine-friendly alternative to `set_exit_callback` 
+        (and a replacement for the blocking `subprocess.Popen.wait`). 
+ 
+        By default, raises `subprocess.CalledProcessError` if the process 
+        has a non-zero exit status. Use ``wait_for_exit(raise_error=False)`` 
+        to suppress this behavior and return the exit status without raising. 
+ 
+        .. versionadded:: 4.2 
+        """ 
+        future = Future() 
+ 
+        def callback(ret): 
+            if ret != 0 and raise_error: 
+                # Unfortunately we don't have the original args any more. 
+                future.set_exception(CalledProcessError(ret, None)) 
+            else: 
+                future.set_result(ret) 
+        self.set_exit_callback(callback) 
+        return future 
+ 
+    @classmethod 
+    def initialize(cls, io_loop=None): 
+        """Initializes the ``SIGCHLD`` handler. 
+ 
+        The signal handler is run on an `.IOLoop` to avoid locking issues. 
+        Note that the `.IOLoop` used for signal handling need not be the 
+        same one used by individual Subprocess objects (as long as the 
+        ``IOLoops`` are each running in separate threads). 
+ 
+        .. versionchanged:: 4.1 
+           The ``io_loop`` argument is deprecated. 
+        """ 
+        if cls._initialized: 
+            return 
+        if io_loop is None: 
+            io_loop = ioloop.IOLoop.current() 
+        cls._old_sigchld = signal.signal( 
+            signal.SIGCHLD, 
+            lambda sig, frame: io_loop.add_callback_from_signal(cls._cleanup)) 
+        cls._initialized = True 
+ 
+    @classmethod 
+    def uninitialize(cls): 
+        """Removes the ``SIGCHLD`` handler.""" 
+        if not cls._initialized: 
+            return 
+        signal.signal(signal.SIGCHLD, cls._old_sigchld) 
+        cls._initialized = False 
+ 
+    @classmethod 
+    def _cleanup(cls): 
+        for pid in list(cls._waiting.keys()):  # make a copy 
+            cls._try_cleanup_process(pid) 
+ 
+    @classmethod 
+    def _try_cleanup_process(cls, pid): 
+        try: 
+            ret_pid, status = os.waitpid(pid, os.WNOHANG) 
+        except OSError as e: 
+            if errno_from_exception(e) == errno.ECHILD: 
+                return 
+        if ret_pid == 0: 
+            return 
+        assert ret_pid == pid 
+        subproc = cls._waiting.pop(pid) 
+        subproc.io_loop.add_callback_from_signal( 
+            subproc._set_returncode, status) 
+ 
+    def _set_returncode(self, status): 
+        if os.WIFSIGNALED(status): 
+            self.returncode = -os.WTERMSIG(status) 
+        else: 
+            assert os.WIFEXITED(status) 
+            self.returncode = os.WEXITSTATUS(status) 
+        # We've taken over wait() duty from the subprocess.Popen 
+        # object. If we don't inform it of the process's return code, 
+        # it will log a warning at destruction in python 3.6+. 
+        self.proc.returncode = self.returncode 
+        if self._exit_callback: 
+            callback = self._exit_callback 
+            self._exit_callback = None 
+            callback(self.returncode) 
diff --git a/contrib/python/tornado/tornado-4/tornado/queues.py b/contrib/python/tornado/tornado-4/tornado/queues.py
index 0041a80086..76c4843b8b 100644
--- a/contrib/python/tornado/tornado-4/tornado/queues.py
+++ b/contrib/python/tornado/tornado-4/tornado/queues.py
@@ -1,367 +1,367 @@
-# Copyright 2015 The Tornado Authors
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Asynchronous queues for coroutines.
-
-.. warning::
-
-   Unlike the standard library's `queue` module, the classes defined here
-   are *not* thread-safe. To use these queues from another thread,
-   use `.IOLoop.add_callback` to transfer control to the `.IOLoop` thread
-   before calling any queue methods.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import collections
-import heapq
-
-from tornado import gen, ioloop
-from tornado.concurrent import Future
-from tornado.locks import Event
-
-__all__ = ['Queue', 'PriorityQueue', 'LifoQueue', 'QueueFull', 'QueueEmpty']
-
-
-class QueueEmpty(Exception):
-    """Raised by `.Queue.get_nowait` when the queue has no items."""
-    pass
-
-
-class QueueFull(Exception):
-    """Raised by `.Queue.put_nowait` when a queue is at its maximum size."""
-    pass
-
-
-def _set_timeout(future, timeout):
-    if timeout:
-        def on_timeout():
-            future.set_exception(gen.TimeoutError())
-        io_loop = ioloop.IOLoop.current()
-        timeout_handle = io_loop.add_timeout(timeout, on_timeout)
-        future.add_done_callback(
-            lambda _: io_loop.remove_timeout(timeout_handle))
-
-
-class _QueueIterator(object):
-    def __init__(self, q):
-        self.q = q
-
-    def __anext__(self):
-        return self.q.get()
-
-
-class Queue(object):
-    """Coordinate producer and consumer coroutines.
-
-    If maxsize is 0 (the default) the queue size is unbounded.
-
-    .. testcode::
-
-        from tornado import gen
-        from tornado.ioloop import IOLoop
-        from tornado.queues import Queue
-
-        q = Queue(maxsize=2)
-
-        @gen.coroutine
-        def consumer():
-            while True:
-                item = yield q.get()
-                try:
-                    print('Doing work on %s' % item)
-                    yield gen.sleep(0.01)
-                finally:
-                    q.task_done()
-
-        @gen.coroutine
-        def producer():
-            for item in range(5):
-                yield q.put(item)
-                print('Put %s' % item)
-
-        @gen.coroutine
-        def main():
-            # Start consumer without waiting (since it never finishes).
-            IOLoop.current().spawn_callback(consumer)
-            yield producer()     # Wait for producer to put all tasks.
-            yield q.join()       # Wait for consumer to finish all tasks.
-            print('Done')
-
-        IOLoop.current().run_sync(main)
-
-    .. testoutput::
-
-        Put 0
-        Put 1
-        Doing work on 0
-        Put 2
-        Doing work on 1
-        Put 3
-        Doing work on 2
-        Put 4
-        Doing work on 3
-        Doing work on 4
-        Done
-
-    In Python 3.5, `Queue` implements the async iterator protocol, so
-    ``consumer()`` could be rewritten as::
-
-        async def consumer():
-            async for item in q:
-                try:
-                    print('Doing work on %s' % item)
-                    yield gen.sleep(0.01)
-                finally:
-                    q.task_done()
-
-    .. versionchanged:: 4.3
-       Added ``async for`` support in Python 3.5.
-
-    """
-    def __init__(self, maxsize=0):
-        if maxsize is None:
-            raise TypeError("maxsize can't be None")
-
-        if maxsize < 0:
-            raise ValueError("maxsize can't be negative")
-
-        self._maxsize = maxsize
-        self._init()
-        self._getters = collections.deque([])  # Futures.
-        self._putters = collections.deque([])  # Pairs of (item, Future).
-        self._unfinished_tasks = 0
-        self._finished = Event()
-        self._finished.set()
-
-    @property
-    def maxsize(self):
-        """Number of items allowed in the queue."""
-        return self._maxsize
-
-    def qsize(self):
-        """Number of items in the queue."""
-        return len(self._queue)
-
-    def empty(self):
-        return not self._queue
-
-    def full(self):
-        if self.maxsize == 0:
-            return False
-        else:
-            return self.qsize() >= self.maxsize
-
-    def put(self, item, timeout=None):
-        """Put an item into the queue, perhaps waiting until there is room.
-
-        Returns a Future, which raises `tornado.gen.TimeoutError` after a
-        timeout.
-        """
-        try:
-            self.put_nowait(item)
-        except QueueFull:
-            future = Future()
-            self._putters.append((item, future))
-            _set_timeout(future, timeout)
-            return future
-        else:
-            return gen._null_future
-
-    def put_nowait(self, item):
-        """Put an item into the queue without blocking.
-
-        If no free slot is immediately available, raise `QueueFull`.
-        """
-        self._consume_expired()
-        if self._getters:
-            assert self.empty(), "queue non-empty, why are getters waiting?"
-            getter = self._getters.popleft()
-            self.__put_internal(item)
-            getter.set_result(self._get())
-        elif self.full():
-            raise QueueFull
-        else:
-            self.__put_internal(item)
-
-    def get(self, timeout=None):
-        """Remove and return an item from the queue.
-
-        Returns a Future which resolves once an item is available, or raises
-        `tornado.gen.TimeoutError` after a timeout.
-        """
-        future = Future()
-        try:
-            future.set_result(self.get_nowait())
-        except QueueEmpty:
-            self._getters.append(future)
-            _set_timeout(future, timeout)
-        return future
-
-    def get_nowait(self):
-        """Remove and return an item from the queue without blocking.
-
-        Return an item if one is immediately available, else raise
-        `QueueEmpty`.
-        """
-        self._consume_expired()
-        if self._putters:
-            assert self.full(), "queue not full, why are putters waiting?"
-            item, putter = self._putters.popleft()
-            self.__put_internal(item)
-            putter.set_result(None)
-            return self._get()
-        elif self.qsize():
-            return self._get()
-        else:
-            raise QueueEmpty
-
-    def task_done(self):
-        """Indicate that a formerly enqueued task is complete.
-
-        Used by queue consumers. For each `.get` used to fetch a task, a
-        subsequent call to `.task_done` tells the queue that the processing
-        on the task is complete.
-
-        If a `.join` is blocking, it resumes when all items have been
-        processed; that is, when every `.put` is matched by a `.task_done`.
-
-        Raises `ValueError` if called more times than `.put`.
-        """
-        if self._unfinished_tasks <= 0:
-            raise ValueError('task_done() called too many times')
-        self._unfinished_tasks -= 1
-        if self._unfinished_tasks == 0:
-            self._finished.set()
-
-    def join(self, timeout=None):
-        """Block until all items in the queue are processed.
-
-        Returns a Future, which raises `tornado.gen.TimeoutError` after a
-        timeout.
-        """
-        return self._finished.wait(timeout)
-
-    @gen.coroutine
-    def __aiter__(self):
-        return _QueueIterator(self)
-
-    # These three are overridable in subclasses.
-    def _init(self):
-        self._queue = collections.deque()
-
-    def _get(self):
-        return self._queue.popleft()
-
-    def _put(self, item):
-        self._queue.append(item)
-    # End of the overridable methods.
-
-    def __put_internal(self, item):
-        self._unfinished_tasks += 1
-        self._finished.clear()
-        self._put(item)
-
-    def _consume_expired(self):
-        # Remove timed-out waiters.
-        while self._putters and self._putters[0][1].done():
-            self._putters.popleft()
-
-        while self._getters and self._getters[0].done():
-            self._getters.popleft()
-
-    def __repr__(self):
-        return '<%s at %s %s>' % (
-            type(self).__name__, hex(id(self)), self._format())
-
-    def __str__(self):
-        return '<%s %s>' % (type(self).__name__, self._format())
-
-    def _format(self):
-        result = 'maxsize=%r' % (self.maxsize, )
-        if getattr(self, '_queue', None):
-            result += ' queue=%r' % self._queue
-        if self._getters:
-            result += ' getters[%s]' % len(self._getters)
-        if self._putters:
-            result += ' putters[%s]' % len(self._putters)
-        if self._unfinished_tasks:
-            result += ' tasks=%s' % self._unfinished_tasks
-        return result
-
-
-class PriorityQueue(Queue):
-    """A `.Queue` that retrieves entries in priority order, lowest first.
-
-    Entries are typically tuples like ``(priority number, data)``.
-
-    .. testcode::
-
-        from tornado.queues import PriorityQueue
-
-        q = PriorityQueue()
-        q.put((1, 'medium-priority item'))
-        q.put((0, 'high-priority item'))
-        q.put((10, 'low-priority item'))
-
-        print(q.get_nowait())
-        print(q.get_nowait())
-        print(q.get_nowait())
-
-    .. testoutput::
-
-        (0, 'high-priority item')
-        (1, 'medium-priority item')
-        (10, 'low-priority item')
-    """
-    def _init(self):
-        self._queue = []
-
-    def _put(self, item):
-        heapq.heappush(self._queue, item)
-
-    def _get(self):
-        return heapq.heappop(self._queue)
-
-
-class LifoQueue(Queue):
-    """A `.Queue` that retrieves the most recently put items first.
-
-    .. testcode::
-
-        from tornado.queues import LifoQueue
-
-        q = LifoQueue()
-        q.put(3)
-        q.put(2)
-        q.put(1)
-
-        print(q.get_nowait())
-        print(q.get_nowait())
-        print(q.get_nowait())
-
-    .. testoutput::
-
-        1
-        2
-        3
-    """
-    def _init(self):
-        self._queue = []
-
-    def _put(self, item):
-        self._queue.append(item)
-
-    def _get(self):
-        return self._queue.pop()
+# Copyright 2015 The Tornado Authors 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Asynchronous queues for coroutines. 
+ 
+.. warning:: 
+ 
+   Unlike the standard library's `queue` module, the classes defined here 
+   are *not* thread-safe. To use these queues from another thread, 
+   use `.IOLoop.add_callback` to transfer control to the `.IOLoop` thread 
+   before calling any queue methods. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import collections 
+import heapq 
+ 
+from tornado import gen, ioloop 
+from tornado.concurrent import Future 
+from tornado.locks import Event 
+ 
+__all__ = ['Queue', 'PriorityQueue', 'LifoQueue', 'QueueFull', 'QueueEmpty'] 
+ 
+ 
+class QueueEmpty(Exception): 
+    """Raised by `.Queue.get_nowait` when the queue has no items.""" 
+    pass 
+ 
+ 
+class QueueFull(Exception): 
+    """Raised by `.Queue.put_nowait` when a queue is at its maximum size.""" 
+    pass 
+ 
+ 
+def _set_timeout(future, timeout): 
+    if timeout: 
+        def on_timeout(): 
+            future.set_exception(gen.TimeoutError()) 
+        io_loop = ioloop.IOLoop.current() 
+        timeout_handle = io_loop.add_timeout(timeout, on_timeout) 
+        future.add_done_callback( 
+            lambda _: io_loop.remove_timeout(timeout_handle)) 
+ 
+ 
+class _QueueIterator(object): 
+    def __init__(self, q): 
+        self.q = q 
+ 
+    def __anext__(self): 
+        return self.q.get() 
+ 
+ 
+class Queue(object): 
+    """Coordinate producer and consumer coroutines. 
+ 
+    If maxsize is 0 (the default) the queue size is unbounded. 
+ 
+    .. testcode:: 
+ 
+        from tornado import gen 
+        from tornado.ioloop import IOLoop 
+        from tornado.queues import Queue 
+ 
+        q = Queue(maxsize=2) 
+ 
+        @gen.coroutine 
+        def consumer(): 
+            while True: 
+                item = yield q.get() 
+                try: 
+                    print('Doing work on %s' % item) 
+                    yield gen.sleep(0.01) 
+                finally: 
+                    q.task_done() 
+ 
+        @gen.coroutine 
+        def producer(): 
+            for item in range(5): 
+                yield q.put(item) 
+                print('Put %s' % item) 
+ 
+        @gen.coroutine 
+        def main(): 
+            # Start consumer without waiting (since it never finishes). 
+            IOLoop.current().spawn_callback(consumer) 
+            yield producer()     # Wait for producer to put all tasks. 
+            yield q.join()       # Wait for consumer to finish all tasks. 
+            print('Done') 
+ 
+        IOLoop.current().run_sync(main) 
+ 
+    .. testoutput:: 
+ 
+        Put 0 
+        Put 1 
+        Doing work on 0 
+        Put 2 
+        Doing work on 1 
+        Put 3 
+        Doing work on 2 
+        Put 4 
+        Doing work on 3 
+        Doing work on 4 
+        Done 
+ 
+    In Python 3.5, `Queue` implements the async iterator protocol, so 
+    ``consumer()`` could be rewritten as:: 
+ 
+        async def consumer(): 
+            async for item in q: 
+                try: 
+                    print('Doing work on %s' % item) 
+                    yield gen.sleep(0.01) 
+                finally: 
+                    q.task_done() 
+ 
+    .. versionchanged:: 4.3 
+       Added ``async for`` support in Python 3.5. 
+ 
+    """ 
+    def __init__(self, maxsize=0): 
+        if maxsize is None: 
+            raise TypeError("maxsize can't be None") 
+ 
+        if maxsize < 0: 
+            raise ValueError("maxsize can't be negative") 
+ 
+        self._maxsize = maxsize 
+        self._init() 
+        self._getters = collections.deque([])  # Futures. 
+        self._putters = collections.deque([])  # Pairs of (item, Future). 
+        self._unfinished_tasks = 0 
+        self._finished = Event() 
+        self._finished.set() 
+ 
+    @property 
+    def maxsize(self): 
+        """Number of items allowed in the queue.""" 
+        return self._maxsize 
+ 
+    def qsize(self): 
+        """Number of items in the queue.""" 
+        return len(self._queue) 
+ 
+    def empty(self): 
+        return not self._queue 
+ 
+    def full(self): 
+        if self.maxsize == 0: 
+            return False 
+        else: 
+            return self.qsize() >= self.maxsize 
+ 
+    def put(self, item, timeout=None): 
+        """Put an item into the queue, perhaps waiting until there is room. 
+ 
+        Returns a Future, which raises `tornado.gen.TimeoutError` after a 
+        timeout. 
+        """ 
+        try: 
+            self.put_nowait(item) 
+        except QueueFull: 
+            future = Future() 
+            self._putters.append((item, future)) 
+            _set_timeout(future, timeout) 
+            return future 
+        else: 
+            return gen._null_future 
+ 
+    def put_nowait(self, item): 
+        """Put an item into the queue without blocking. 
+ 
+        If no free slot is immediately available, raise `QueueFull`. 
+        """ 
+        self._consume_expired() 
+        if self._getters: 
+            assert self.empty(), "queue non-empty, why are getters waiting?" 
+            getter = self._getters.popleft() 
+            self.__put_internal(item) 
+            getter.set_result(self._get()) 
+        elif self.full(): 
+            raise QueueFull 
+        else: 
+            self.__put_internal(item) 
+ 
+    def get(self, timeout=None): 
+        """Remove and return an item from the queue. 
+ 
+        Returns a Future which resolves once an item is available, or raises 
+        `tornado.gen.TimeoutError` after a timeout. 
+        """ 
+        future = Future() 
+        try: 
+            future.set_result(self.get_nowait()) 
+        except QueueEmpty: 
+            self._getters.append(future) 
+            _set_timeout(future, timeout) 
+        return future 
+ 
+    def get_nowait(self): 
+        """Remove and return an item from the queue without blocking. 
+ 
+        Return an item if one is immediately available, else raise 
+        `QueueEmpty`. 
+        """ 
+        self._consume_expired() 
+        if self._putters: 
+            assert self.full(), "queue not full, why are putters waiting?" 
+            item, putter = self._putters.popleft() 
+            self.__put_internal(item) 
+            putter.set_result(None) 
+            return self._get() 
+        elif self.qsize(): 
+            return self._get() 
+        else: 
+            raise QueueEmpty 
+ 
+    def task_done(self): 
+        """Indicate that a formerly enqueued task is complete. 
+ 
+        Used by queue consumers. For each `.get` used to fetch a task, a 
+        subsequent call to `.task_done` tells the queue that the processing 
+        on the task is complete. 
+ 
+        If a `.join` is blocking, it resumes when all items have been 
+        processed; that is, when every `.put` is matched by a `.task_done`. 
+ 
+        Raises `ValueError` if called more times than `.put`. 
+        """ 
+        if self._unfinished_tasks <= 0: 
+            raise ValueError('task_done() called too many times') 
+        self._unfinished_tasks -= 1 
+        if self._unfinished_tasks == 0: 
+            self._finished.set() 
+ 
+    def join(self, timeout=None): 
+        """Block until all items in the queue are processed. 
+ 
+        Returns a Future, which raises `tornado.gen.TimeoutError` after a 
+        timeout. 
+        """ 
+        return self._finished.wait(timeout) 
+ 
+    @gen.coroutine 
+    def __aiter__(self): 
+        return _QueueIterator(self) 
+ 
+    # These three are overridable in subclasses. 
+    def _init(self): 
+        self._queue = collections.deque() 
+ 
+    def _get(self): 
+        return self._queue.popleft() 
+ 
+    def _put(self, item): 
+        self._queue.append(item) 
+    # End of the overridable methods. 
+ 
+    def __put_internal(self, item): 
+        self._unfinished_tasks += 1 
+        self._finished.clear() 
+        self._put(item) 
+ 
+    def _consume_expired(self): 
+        # Remove timed-out waiters. 
+        while self._putters and self._putters[0][1].done(): 
+            self._putters.popleft() 
+ 
+        while self._getters and self._getters[0].done(): 
+            self._getters.popleft() 
+ 
+    def __repr__(self): 
+        return '<%s at %s %s>' % ( 
+            type(self).__name__, hex(id(self)), self._format()) 
+ 
+    def __str__(self): 
+        return '<%s %s>' % (type(self).__name__, self._format()) 
+ 
+    def _format(self): 
+        result = 'maxsize=%r' % (self.maxsize, ) 
+        if getattr(self, '_queue', None): 
+            result += ' queue=%r' % self._queue 
+        if self._getters: 
+            result += ' getters[%s]' % len(self._getters) 
+        if self._putters: 
+            result += ' putters[%s]' % len(self._putters) 
+        if self._unfinished_tasks: 
+            result += ' tasks=%s' % self._unfinished_tasks 
+        return result 
+ 
+ 
+class PriorityQueue(Queue): 
+    """A `.Queue` that retrieves entries in priority order, lowest first. 
+ 
+    Entries are typically tuples like ``(priority number, data)``. 
+ 
+    .. testcode:: 
+ 
+        from tornado.queues import PriorityQueue 
+ 
+        q = PriorityQueue() 
+        q.put((1, 'medium-priority item')) 
+        q.put((0, 'high-priority item')) 
+        q.put((10, 'low-priority item')) 
+ 
+        print(q.get_nowait()) 
+        print(q.get_nowait()) 
+        print(q.get_nowait()) 
+ 
+    .. testoutput:: 
+ 
+        (0, 'high-priority item') 
+        (1, 'medium-priority item') 
+        (10, 'low-priority item') 
+    """ 
+    def _init(self): 
+        self._queue = [] 
+ 
+    def _put(self, item): 
+        heapq.heappush(self._queue, item) 
+ 
+    def _get(self): 
+        return heapq.heappop(self._queue) 
+ 
+ 
+class LifoQueue(Queue): 
+    """A `.Queue` that retrieves the most recently put items first. 
+ 
+    .. testcode:: 
+ 
+        from tornado.queues import LifoQueue 
+ 
+        q = LifoQueue() 
+        q.put(3) 
+        q.put(2) 
+        q.put(1) 
+ 
+        print(q.get_nowait()) 
+        print(q.get_nowait()) 
+        print(q.get_nowait()) 
+ 
+    .. testoutput:: 
+ 
+        1 
+        2 
+        3 
+    """ 
+    def _init(self): 
+        self._queue = [] 
+ 
+    def _put(self, item): 
+        self._queue.append(item) 
+ 
+    def _get(self): 
+        return self._queue.pop() 
diff --git a/contrib/python/tornado/tornado-4/tornado/routing.py b/contrib/python/tornado/tornado-4/tornado/routing.py
index 6762dc05bc..2f7e036e1d 100644
--- a/contrib/python/tornado/tornado-4/tornado/routing.py
+++ b/contrib/python/tornado/tornado-4/tornado/routing.py
@@ -1,625 +1,625 @@
-# Copyright 2015 The Tornado Authors
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""Flexible routing implementation.
-
-Tornado routes HTTP requests to appropriate handlers using `Router`
-class implementations. The `tornado.web.Application` class is a
-`Router` implementation and may be used directly, or the classes in
-this module may be used for additional flexibility. The `RuleRouter`
-class can match on more criteria than `.Application`, or the `Router`
-interface can be subclassed for maximum customization.
-
-`Router` interface extends `~.httputil.HTTPServerConnectionDelegate`
-to provide additional routing capabilities. This also means that any
-`Router` implementation can be used directly as a ``request_callback``
-for `~.httpserver.HTTPServer` constructor.
-
-`Router` subclass must implement a ``find_handler`` method to provide
-a suitable `~.httputil.HTTPMessageDelegate` instance to handle the
-request:
-
-.. code-block:: python
-
-    class CustomRouter(Router):
-        def find_handler(self, request, **kwargs):
-            # some routing logic providing a suitable HTTPMessageDelegate instance
-            return MessageDelegate(request.connection)
-
-    class MessageDelegate(HTTPMessageDelegate):
-        def __init__(self, connection):
-            self.connection = connection
-
-        def finish(self):
-            self.connection.write_headers(
-                ResponseStartLine("HTTP/1.1", 200, "OK"),
-                HTTPHeaders({"Content-Length": "2"}),
-                b"OK")
-            self.connection.finish()
-
-    router = CustomRouter()
-    server = HTTPServer(router)
-
-The main responsibility of `Router` implementation is to provide a
-mapping from a request to `~.httputil.HTTPMessageDelegate` instance
-that will handle this request. In the example above we can see that
-routing is possible even without instantiating an `~.web.Application`.
-
-For routing to `~.web.RequestHandler` implementations we need an
-`~.web.Application` instance. `~.web.Application.get_handler_delegate`
-provides a convenient way to create `~.httputil.HTTPMessageDelegate`
-for a given request and `~.web.RequestHandler`.
-
-Here is a simple example of how we can we route to
-`~.web.RequestHandler` subclasses by HTTP method:
-
-.. code-block:: python
-
-    resources = {}
-
-    class GetResource(RequestHandler):
-        def get(self, path):
-            if path not in resources:
-                raise HTTPError(404)
-
-            self.finish(resources[path])
-
-    class PostResource(RequestHandler):
-        def post(self, path):
-            resources[path] = self.request.body
-
-    class HTTPMethodRouter(Router):
-        def __init__(self, app):
-            self.app = app
-
-        def find_handler(self, request, **kwargs):
-            handler = GetResource if request.method == "GET" else PostResource
-            return self.app.get_handler_delegate(request, handler, path_args=[request.path])
-
-    router = HTTPMethodRouter(Application())
-    server = HTTPServer(router)
-
-`ReversibleRouter` interface adds the ability to distinguish between
-the routes and reverse them to the original urls using route's name
-and additional arguments. `~.web.Application` is itself an
-implementation of `ReversibleRouter` class.
-
-`RuleRouter` and `ReversibleRuleRouter` are implementations of
-`Router` and `ReversibleRouter` interfaces and can be used for
-creating rule-based routing configurations.
-
-Rules are instances of `Rule` class. They contain a `Matcher`, which
-provides the logic for determining whether the rule is a match for a
-particular request and a target, which can be one of the following.
-
-1) An instance of `~.httputil.HTTPServerConnectionDelegate`:
-
-.. code-block:: python
-
-    router = RuleRouter([
-        Rule(PathMatches("/handler"), ConnectionDelegate()),
-        # ... more rules
-    ])
-
-    class ConnectionDelegate(HTTPServerConnectionDelegate):
-        def start_request(self, server_conn, request_conn):
-            return MessageDelegate(request_conn)
-
-2) A callable accepting a single argument of `~.httputil.HTTPServerRequest` type:
-
-.. code-block:: python
-
-    router = RuleRouter([
-        Rule(PathMatches("/callable"), request_callable)
-    ])
-
-    def request_callable(request):
-        request.write(b"HTTP/1.1 200 OK\\r\\nContent-Length: 2\\r\\n\\r\\nOK")
-        request.finish()
-
-3) Another `Router` instance:
-
-.. code-block:: python
-
-    router = RuleRouter([
-        Rule(PathMatches("/router.*"), CustomRouter())
-    ])
-
-Of course a nested `RuleRouter` or a `~.web.Application` is allowed:
-
-.. code-block:: python
-
-    router = RuleRouter([
-        Rule(HostMatches("example.com"), RuleRouter([
-            Rule(PathMatches("/app1/.*"), Application([(r"/app1/handler", Handler)]))),
-        ]))
-    ])
-
-    server = HTTPServer(router)
-
-In the example below `RuleRouter` is used to route between applications:
-
-.. code-block:: python
-
-    app1 = Application([
-        (r"/app1/handler", Handler1),
-        # other handlers ...
-    ])
-
-    app2 = Application([
-        (r"/app2/handler", Handler2),
-        # other handlers ...
-    ])
-
-    router = RuleRouter([
-        Rule(PathMatches("/app1.*"), app1),
-        Rule(PathMatches("/app2.*"), app2)
-    ])
-
-    server = HTTPServer(router)
-
-For more information on application-level routing see docs for `~.web.Application`.
-
-.. versionadded:: 4.5
-
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import re
-from functools import partial
-
-from tornado import httputil
-from tornado.httpserver import _CallableAdapter
-from tornado.escape import url_escape, url_unescape, utf8
-from tornado.log import app_log
-from tornado.util import basestring_type, import_object, re_unescape, unicode_type
-
-try:
-    import typing  # noqa
-except ImportError:
-    pass
-
-
-class Router(httputil.HTTPServerConnectionDelegate):
-    """Abstract router interface."""
-
-    def find_handler(self, request, **kwargs):
-        # type: (httputil.HTTPServerRequest, typing.Any)->httputil.HTTPMessageDelegate
-        """Must be implemented to return an appropriate instance of `~.httputil.HTTPMessageDelegate`
-        that can serve the request.
-        Routing implementations may pass additional kwargs to extend the routing logic.
-
-        :arg httputil.HTTPServerRequest request: current HTTP request.
-        :arg kwargs: additional keyword arguments passed by routing implementation.
-        :returns: an instance of `~.httputil.HTTPMessageDelegate` that will be used to
-            process the request.
-        """
-        raise NotImplementedError()
-
-    def start_request(self, server_conn, request_conn):
-        return _RoutingDelegate(self, server_conn, request_conn)
-
-
-class ReversibleRouter(Router):
-    """Abstract router interface for routers that can handle named routes
-    and support reversing them to original urls.
-    """
-
-    def reverse_url(self, name, *args):
-        """Returns url string for a given route name and arguments
-        or ``None`` if no match is found.
-
-        :arg str name: route name.
-        :arg args: url parameters.
-        :returns: parametrized url string for a given route name (or ``None``).
-        """
-        raise NotImplementedError()
-
-
-class _RoutingDelegate(httputil.HTTPMessageDelegate):
-    def __init__(self, router, server_conn, request_conn):
-        self.server_conn = server_conn
-        self.request_conn = request_conn
-        self.delegate = None
-        self.router = router  # type: Router
-
-    def headers_received(self, start_line, headers):
-        request = httputil.HTTPServerRequest(
-            connection=self.request_conn,
-            server_connection=self.server_conn,
-            start_line=start_line, headers=headers)
-
-        self.delegate = self.router.find_handler(request)
-        return self.delegate.headers_received(start_line, headers)
-
-    def data_received(self, chunk):
-        return self.delegate.data_received(chunk)
-
-    def finish(self):
-        self.delegate.finish()
-
-    def on_connection_close(self):
-        self.delegate.on_connection_close()
-
-
-class RuleRouter(Router):
-    """Rule-based router implementation."""
-
-    def __init__(self, rules=None):
-        """Constructs a router from an ordered list of rules::
-
-            RuleRouter([
-                Rule(PathMatches("/handler"), Target),
-                # ... more rules
-            ])
-
-        You can also omit explicit `Rule` constructor and use tuples of arguments::
-
-            RuleRouter([
-                (PathMatches("/handler"), Target),
-            ])
-
-        `PathMatches` is a default matcher, so the example above can be simplified::
-
-            RuleRouter([
-                ("/handler", Target),
-            ])
-
-        In the examples above, ``Target`` can be a nested `Router` instance, an instance of
-        `~.httputil.HTTPServerConnectionDelegate` or an old-style callable, accepting a request argument.
-
-        :arg rules: a list of `Rule` instances or tuples of `Rule`
-            constructor arguments.
-        """
-        self.rules = []  # type: typing.List[Rule]
-        if rules:
-            self.add_rules(rules)
-
-    def add_rules(self, rules):
-        """Appends new rules to the router.
-
-        :arg rules: a list of Rule instances (or tuples of arguments, which are
-            passed to Rule constructor).
-        """
-        for rule in rules:
-            if isinstance(rule, (tuple, list)):
-                assert len(rule) in (2, 3, 4)
-                if isinstance(rule[0], basestring_type):
-                    rule = Rule(PathMatches(rule[0]), *rule[1:])
-                else:
-                    rule = Rule(*rule)
-
-            self.rules.append(self.process_rule(rule))
-
-    def process_rule(self, rule):
-        """Override this method for additional preprocessing of each rule.
-
-        :arg Rule rule: a rule to be processed.
-        :returns: the same or modified Rule instance.
-        """
-        return rule
-
-    def find_handler(self, request, **kwargs):
-        for rule in self.rules:
-            target_params = rule.matcher.match(request)
-            if target_params is not None:
-                if rule.target_kwargs:
-                    target_params['target_kwargs'] = rule.target_kwargs
-
-                delegate = self.get_target_delegate(
-                    rule.target, request, **target_params)
-
-                if delegate is not None:
-                    return delegate
-
-        return None
-
-    def get_target_delegate(self, target, request, **target_params):
-        """Returns an instance of `~.httputil.HTTPMessageDelegate` for a
-        Rule's target. This method is called by `~.find_handler` and can be
-        extended to provide additional target types.
-
-        :arg target: a Rule's target.
-        :arg httputil.HTTPServerRequest request: current request.
-        :arg target_params: additional parameters that can be useful
-            for `~.httputil.HTTPMessageDelegate` creation.
-        """
-        if isinstance(target, Router):
-            return target.find_handler(request, **target_params)
-
-        elif isinstance(target, httputil.HTTPServerConnectionDelegate):
-            return target.start_request(request.server_connection, request.connection)
-
-        elif callable(target):
-            return _CallableAdapter(
-                partial(target, **target_params), request.connection
-            )
-
-        return None
-
-
-class ReversibleRuleRouter(ReversibleRouter, RuleRouter):
-    """A rule-based router that implements ``reverse_url`` method.
-
-    Each rule added to this router may have a ``name`` attribute that can be
-    used to reconstruct an original uri. The actual reconstruction takes place
-    in a rule's matcher (see `Matcher.reverse`).
-    """
-
-    def __init__(self, rules=None):
-        self.named_rules = {}  # type: typing.Dict[str]
-        super(ReversibleRuleRouter, self).__init__(rules)
-
-    def process_rule(self, rule):
-        rule = super(ReversibleRuleRouter, self).process_rule(rule)
-
-        if rule.name:
-            if rule.name in self.named_rules:
-                app_log.warning(
-                    "Multiple handlers named %s; replacing previous value",
-                    rule.name)
-            self.named_rules[rule.name] = rule
-
-        return rule
-
-    def reverse_url(self, name, *args):
-        if name in self.named_rules:
-            return self.named_rules[name].matcher.reverse(*args)
-
-        for rule in self.rules:
-            if isinstance(rule.target, ReversibleRouter):
-                reversed_url = rule.target.reverse_url(name, *args)
-                if reversed_url is not None:
-                    return reversed_url
-
-        return None
-
-
-class Rule(object):
-    """A routing rule."""
-
-    def __init__(self, matcher, target, target_kwargs=None, name=None):
-        """Constructs a Rule instance.
-
-        :arg Matcher matcher: a `Matcher` instance used for determining
-            whether the rule should be considered a match for a specific
-            request.
-        :arg target: a Rule's target (typically a ``RequestHandler`` or
-            `~.httputil.HTTPServerConnectionDelegate` subclass or even a nested `Router`,
-            depending on routing implementation).
-        :arg dict target_kwargs: a dict of parameters that can be useful
-            at the moment of target instantiation (for example, ``status_code``
-            for a ``RequestHandler`` subclass). They end up in
-            ``target_params['target_kwargs']`` of `RuleRouter.get_target_delegate`
-            method.
-        :arg str name: the name of the rule that can be used to find it
-            in `ReversibleRouter.reverse_url` implementation.
-        """
-        if isinstance(target, str):
-            # import the Module and instantiate the class
-            # Must be a fully qualified name (module.ClassName)
-            target = import_object(target)
-
-        self.matcher = matcher  # type: Matcher
-        self.target = target
-        self.target_kwargs = target_kwargs if target_kwargs else {}
-        self.name = name
-
-    def reverse(self, *args):
-        return self.matcher.reverse(*args)
-
-    def __repr__(self):
-        return '%s(%r, %s, kwargs=%r, name=%r)' % \
-               (self.__class__.__name__, self.matcher,
-                self.target, self.target_kwargs, self.name)
-
-
-class Matcher(object):
-    """Represents a matcher for request features."""
-
-    def match(self, request):
-        """Matches current instance against the request.
-
-        :arg httputil.HTTPServerRequest request: current HTTP request
-        :returns: a dict of parameters to be passed to the target handler
-            (for example, ``handler_kwargs``, ``path_args``, ``path_kwargs``
-            can be passed for proper `~.web.RequestHandler` instantiation).
-            An empty dict is a valid (and common) return value to indicate a match
-            when the argument-passing features are not used.
-            ``None`` must be returned to indicate that there is no match."""
-        raise NotImplementedError()
-
-    def reverse(self, *args):
-        """Reconstructs full url from matcher instance and additional arguments."""
-        return None
-
-
-class AnyMatches(Matcher):
-    """Matches any request."""
-
-    def match(self, request):
-        return {}
-
-
-class HostMatches(Matcher):
-    """Matches requests from hosts specified by ``host_pattern`` regex."""
-
-    def __init__(self, host_pattern):
-        if isinstance(host_pattern, basestring_type):
-            if not host_pattern.endswith("$"):
-                host_pattern += "$"
-            self.host_pattern = re.compile(host_pattern)
-        else:
-            self.host_pattern = host_pattern
-
-    def match(self, request):
-        if self.host_pattern.match(request.host_name):
-            return {}
-
-        return None
-
-
-class DefaultHostMatches(Matcher):
-    """Matches requests from host that is equal to application's default_host.
-    Always returns no match if ``X-Real-Ip`` header is present.
-    """
-
-    def __init__(self, application, host_pattern):
-        self.application = application
-        self.host_pattern = host_pattern
-
-    def match(self, request):
-        # Look for default host if not behind load balancer (for debugging)
-        if "X-Real-Ip" not in request.headers:
-            if self.host_pattern.match(self.application.default_host):
-                return {}
-        return None
-
-
-class PathMatches(Matcher):
-    """Matches requests with paths specified by ``path_pattern`` regex."""
-
-    def __init__(self, path_pattern):
-        if isinstance(path_pattern, basestring_type):
-            if not path_pattern.endswith('$'):
-                path_pattern += '$'
-            self.regex = re.compile(path_pattern)
-        else:
-            self.regex = path_pattern
-
-        assert len(self.regex.groupindex) in (0, self.regex.groups), \
-            ("groups in url regexes must either be all named or all "
-             "positional: %r" % self.regex.pattern)
-
-        self._path, self._group_count = self._find_groups()
-
-    def match(self, request):
-        match = self.regex.match(request.path)
-        if match is None:
-            return None
-        if not self.regex.groups:
-            return {}
-
-        path_args, path_kwargs = [], {}
-
-        # Pass matched groups to the handler.  Since
-        # match.groups() includes both named and
-        # unnamed groups, we want to use either groups
-        # or groupdict but not both.
-        if self.regex.groupindex:
-            path_kwargs = dict(
-                (str(k), _unquote_or_none(v))
-                for (k, v) in match.groupdict().items())
-        else:
-            path_args = [_unquote_or_none(s) for s in match.groups()]
-
-        return dict(path_args=path_args, path_kwargs=path_kwargs)
-
-    def reverse(self, *args):
-        if self._path is None:
-            raise ValueError("Cannot reverse url regex " + self.regex.pattern)
-        assert len(args) == self._group_count, "required number of arguments " \
-                                               "not found"
-        if not len(args):
-            return self._path
-        converted_args = []
-        for a in args:
-            if not isinstance(a, (unicode_type, bytes)):
-                a = str(a)
-            converted_args.append(url_escape(utf8(a), plus=False))
-        return self._path % tuple(converted_args)
-
-    def _find_groups(self):
-        """Returns a tuple (reverse string, group count) for a url.
-
-        For example: Given the url pattern /([0-9]{4})/([a-z-]+)/, this method
-        would return ('/%s/%s/', 2).
-        """
-        pattern = self.regex.pattern
-        if pattern.startswith('^'):
-            pattern = pattern[1:]
-        if pattern.endswith('$'):
-            pattern = pattern[:-1]
-
-        if self.regex.groups != pattern.count('('):
-            # The pattern is too complicated for our simplistic matching,
-            # so we can't support reversing it.
-            return None, None
-
-        pieces = []
-        for fragment in pattern.split('('):
-            if ')' in fragment:
-                paren_loc = fragment.index(')')
-                if paren_loc >= 0:
-                    pieces.append('%s' + fragment[paren_loc + 1:])
-            else:
-                try:
-                    unescaped_fragment = re_unescape(fragment)
-                except ValueError as exc:
-                    # If we can't unescape part of it, we can't
-                    # reverse this url.
-                    return (None, None)
-                pieces.append(unescaped_fragment)
-
-        return ''.join(pieces), self.regex.groups
-
-
-class URLSpec(Rule):
-    """Specifies mappings between URLs and handlers.
-
-    .. versionchanged: 4.5
-       `URLSpec` is now a subclass of a `Rule` with `PathMatches` matcher and is preserved for
-       backwards compatibility.
-    """
-    def __init__(self, pattern, handler, kwargs=None, name=None):
-        """Parameters:
-
-        * ``pattern``: Regular expression to be matched. Any capturing
-          groups in the regex will be passed in to the handler's
-          get/post/etc methods as arguments (by keyword if named, by
-          position if unnamed. Named and unnamed capturing groups may
-          may not be mixed in the same rule).
-
-        * ``handler``: `~.web.RequestHandler` subclass to be invoked.
-
-        * ``kwargs`` (optional): A dictionary of additional arguments
-          to be passed to the handler's constructor.
-
-        * ``name`` (optional): A name for this handler.  Used by
-          `~.web.Application.reverse_url`.
-
-        """
-        super(URLSpec, self).__init__(PathMatches(pattern), handler, kwargs, name)
-
-        self.regex = self.matcher.regex
-        self.handler_class = self.target
-        self.kwargs = kwargs
-
-    def __repr__(self):
-        return '%s(%r, %s, kwargs=%r, name=%r)' % \
-               (self.__class__.__name__, self.regex.pattern,
-                self.handler_class, self.kwargs, self.name)
-
-
-def _unquote_or_none(s):
-    """None-safe wrapper around url_unescape to handle unmatched optional
-    groups correctly.
-
-    Note that args are passed as bytes so the handler can decide what
-    encoding to use.
-    """
-    if s is None:
-        return s
-    return url_unescape(s, encoding=None, plus=False)
+# Copyright 2015 The Tornado Authors 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""Flexible routing implementation. 
+ 
+Tornado routes HTTP requests to appropriate handlers using `Router` 
+class implementations. The `tornado.web.Application` class is a 
+`Router` implementation and may be used directly, or the classes in 
+this module may be used for additional flexibility. The `RuleRouter` 
+class can match on more criteria than `.Application`, or the `Router` 
+interface can be subclassed for maximum customization. 
+ 
+`Router` interface extends `~.httputil.HTTPServerConnectionDelegate` 
+to provide additional routing capabilities. This also means that any 
+`Router` implementation can be used directly as a ``request_callback`` 
+for `~.httpserver.HTTPServer` constructor. 
+ 
+`Router` subclass must implement a ``find_handler`` method to provide 
+a suitable `~.httputil.HTTPMessageDelegate` instance to handle the 
+request: 
+ 
+.. code-block:: python 
+ 
+    class CustomRouter(Router): 
+        def find_handler(self, request, **kwargs): 
+            # some routing logic providing a suitable HTTPMessageDelegate instance 
+            return MessageDelegate(request.connection) 
+ 
+    class MessageDelegate(HTTPMessageDelegate): 
+        def __init__(self, connection): 
+            self.connection = connection 
+ 
+        def finish(self): 
+            self.connection.write_headers( 
+                ResponseStartLine("HTTP/1.1", 200, "OK"), 
+                HTTPHeaders({"Content-Length": "2"}), 
+                b"OK") 
+            self.connection.finish() 
+ 
+    router = CustomRouter() 
+    server = HTTPServer(router) 
+ 
+The main responsibility of `Router` implementation is to provide a 
+mapping from a request to `~.httputil.HTTPMessageDelegate` instance 
+that will handle this request. In the example above we can see that 
+routing is possible even without instantiating an `~.web.Application`. 
+ 
+For routing to `~.web.RequestHandler` implementations we need an 
+`~.web.Application` instance. `~.web.Application.get_handler_delegate` 
+provides a convenient way to create `~.httputil.HTTPMessageDelegate` 
+for a given request and `~.web.RequestHandler`. 
+ 
+Here is a simple example of how we can we route to 
+`~.web.RequestHandler` subclasses by HTTP method: 
+ 
+.. code-block:: python 
+ 
+    resources = {} 
+ 
+    class GetResource(RequestHandler): 
+        def get(self, path): 
+            if path not in resources: 
+                raise HTTPError(404) 
+ 
+            self.finish(resources[path]) 
+ 
+    class PostResource(RequestHandler): 
+        def post(self, path): 
+            resources[path] = self.request.body 
+ 
+    class HTTPMethodRouter(Router): 
+        def __init__(self, app): 
+            self.app = app 
+ 
+        def find_handler(self, request, **kwargs): 
+            handler = GetResource if request.method == "GET" else PostResource 
+            return self.app.get_handler_delegate(request, handler, path_args=[request.path]) 
+ 
+    router = HTTPMethodRouter(Application()) 
+    server = HTTPServer(router) 
+ 
+`ReversibleRouter` interface adds the ability to distinguish between 
+the routes and reverse them to the original urls using route's name 
+and additional arguments. `~.web.Application` is itself an 
+implementation of `ReversibleRouter` class. 
+ 
+`RuleRouter` and `ReversibleRuleRouter` are implementations of 
+`Router` and `ReversibleRouter` interfaces and can be used for 
+creating rule-based routing configurations. 
+ 
+Rules are instances of `Rule` class. They contain a `Matcher`, which 
+provides the logic for determining whether the rule is a match for a 
+particular request and a target, which can be one of the following. 
+ 
+1) An instance of `~.httputil.HTTPServerConnectionDelegate`: 
+ 
+.. code-block:: python 
+ 
+    router = RuleRouter([ 
+        Rule(PathMatches("/handler"), ConnectionDelegate()), 
+        # ... more rules 
+    ]) 
+ 
+    class ConnectionDelegate(HTTPServerConnectionDelegate): 
+        def start_request(self, server_conn, request_conn): 
+            return MessageDelegate(request_conn) 
+ 
+2) A callable accepting a single argument of `~.httputil.HTTPServerRequest` type: 
+ 
+.. code-block:: python 
+ 
+    router = RuleRouter([ 
+        Rule(PathMatches("/callable"), request_callable) 
+    ]) 
+ 
+    def request_callable(request): 
+        request.write(b"HTTP/1.1 200 OK\\r\\nContent-Length: 2\\r\\n\\r\\nOK") 
+        request.finish() 
+ 
+3) Another `Router` instance: 
+ 
+.. code-block:: python 
+ 
+    router = RuleRouter([ 
+        Rule(PathMatches("/router.*"), CustomRouter()) 
+    ]) 
+ 
+Of course a nested `RuleRouter` or a `~.web.Application` is allowed: 
+ 
+.. code-block:: python 
+ 
+    router = RuleRouter([ 
+        Rule(HostMatches("example.com"), RuleRouter([ 
+            Rule(PathMatches("/app1/.*"), Application([(r"/app1/handler", Handler)]))), 
+        ])) 
+    ]) 
+ 
+    server = HTTPServer(router) 
+ 
+In the example below `RuleRouter` is used to route between applications: 
+ 
+.. code-block:: python 
+ 
+    app1 = Application([ 
+        (r"/app1/handler", Handler1), 
+        # other handlers ... 
+    ]) 
+ 
+    app2 = Application([ 
+        (r"/app2/handler", Handler2), 
+        # other handlers ... 
+    ]) 
+ 
+    router = RuleRouter([ 
+        Rule(PathMatches("/app1.*"), app1), 
+        Rule(PathMatches("/app2.*"), app2) 
+    ]) 
+ 
+    server = HTTPServer(router) 
+ 
+For more information on application-level routing see docs for `~.web.Application`. 
+ 
+.. versionadded:: 4.5 
+ 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import re 
+from functools import partial 
+ 
+from tornado import httputil 
+from tornado.httpserver import _CallableAdapter 
+from tornado.escape import url_escape, url_unescape, utf8 
+from tornado.log import app_log 
+from tornado.util import basestring_type, import_object, re_unescape, unicode_type 
+ 
+try: 
+    import typing  # noqa 
+except ImportError: 
+    pass 
+ 
+ 
+class Router(httputil.HTTPServerConnectionDelegate): 
+    """Abstract router interface.""" 
+ 
+    def find_handler(self, request, **kwargs): 
+        # type: (httputil.HTTPServerRequest, typing.Any)->httputil.HTTPMessageDelegate 
+        """Must be implemented to return an appropriate instance of `~.httputil.HTTPMessageDelegate` 
+        that can serve the request. 
+        Routing implementations may pass additional kwargs to extend the routing logic. 
+ 
+        :arg httputil.HTTPServerRequest request: current HTTP request. 
+        :arg kwargs: additional keyword arguments passed by routing implementation. 
+        :returns: an instance of `~.httputil.HTTPMessageDelegate` that will be used to 
+            process the request. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def start_request(self, server_conn, request_conn): 
+        return _RoutingDelegate(self, server_conn, request_conn) 
+ 
+ 
+class ReversibleRouter(Router): 
+    """Abstract router interface for routers that can handle named routes 
+    and support reversing them to original urls. 
+    """ 
+ 
+    def reverse_url(self, name, *args): 
+        """Returns url string for a given route name and arguments 
+        or ``None`` if no match is found. 
+ 
+        :arg str name: route name. 
+        :arg args: url parameters. 
+        :returns: parametrized url string for a given route name (or ``None``). 
+        """ 
+        raise NotImplementedError() 
+ 
+ 
+class _RoutingDelegate(httputil.HTTPMessageDelegate): 
+    def __init__(self, router, server_conn, request_conn): 
+        self.server_conn = server_conn 
+        self.request_conn = request_conn 
+        self.delegate = None 
+        self.router = router  # type: Router 
+ 
+    def headers_received(self, start_line, headers): 
+        request = httputil.HTTPServerRequest( 
+            connection=self.request_conn, 
+            server_connection=self.server_conn, 
+            start_line=start_line, headers=headers) 
+ 
+        self.delegate = self.router.find_handler(request) 
+        return self.delegate.headers_received(start_line, headers) 
+ 
+    def data_received(self, chunk): 
+        return self.delegate.data_received(chunk) 
+ 
+    def finish(self): 
+        self.delegate.finish() 
+ 
+    def on_connection_close(self): 
+        self.delegate.on_connection_close() 
+ 
+ 
+class RuleRouter(Router): 
+    """Rule-based router implementation.""" 
+ 
+    def __init__(self, rules=None): 
+        """Constructs a router from an ordered list of rules:: 
+ 
+            RuleRouter([ 
+                Rule(PathMatches("/handler"), Target), 
+                # ... more rules 
+            ]) 
+ 
+        You can also omit explicit `Rule` constructor and use tuples of arguments:: 
+ 
+            RuleRouter([ 
+                (PathMatches("/handler"), Target), 
+            ]) 
+ 
+        `PathMatches` is a default matcher, so the example above can be simplified:: 
+ 
+            RuleRouter([ 
+                ("/handler", Target), 
+            ]) 
+ 
+        In the examples above, ``Target`` can be a nested `Router` instance, an instance of 
+        `~.httputil.HTTPServerConnectionDelegate` or an old-style callable, accepting a request argument. 
+ 
+        :arg rules: a list of `Rule` instances or tuples of `Rule` 
+            constructor arguments. 
+        """ 
+        self.rules = []  # type: typing.List[Rule] 
+        if rules: 
+            self.add_rules(rules) 
+ 
+    def add_rules(self, rules): 
+        """Appends new rules to the router. 
+ 
+        :arg rules: a list of Rule instances (or tuples of arguments, which are 
+            passed to Rule constructor). 
+        """ 
+        for rule in rules: 
+            if isinstance(rule, (tuple, list)): 
+                assert len(rule) in (2, 3, 4) 
+                if isinstance(rule[0], basestring_type): 
+                    rule = Rule(PathMatches(rule[0]), *rule[1:]) 
+                else: 
+                    rule = Rule(*rule) 
+ 
+            self.rules.append(self.process_rule(rule)) 
+ 
+    def process_rule(self, rule): 
+        """Override this method for additional preprocessing of each rule. 
+ 
+        :arg Rule rule: a rule to be processed. 
+        :returns: the same or modified Rule instance. 
+        """ 
+        return rule 
+ 
+    def find_handler(self, request, **kwargs): 
+        for rule in self.rules: 
+            target_params = rule.matcher.match(request) 
+            if target_params is not None: 
+                if rule.target_kwargs: 
+                    target_params['target_kwargs'] = rule.target_kwargs 
+ 
+                delegate = self.get_target_delegate( 
+                    rule.target, request, **target_params) 
+ 
+                if delegate is not None: 
+                    return delegate 
+ 
+        return None 
+ 
+    def get_target_delegate(self, target, request, **target_params): 
+        """Returns an instance of `~.httputil.HTTPMessageDelegate` for a 
+        Rule's target. This method is called by `~.find_handler` and can be 
+        extended to provide additional target types. 
+ 
+        :arg target: a Rule's target. 
+        :arg httputil.HTTPServerRequest request: current request. 
+        :arg target_params: additional parameters that can be useful 
+            for `~.httputil.HTTPMessageDelegate` creation. 
+        """ 
+        if isinstance(target, Router): 
+            return target.find_handler(request, **target_params) 
+ 
+        elif isinstance(target, httputil.HTTPServerConnectionDelegate): 
+            return target.start_request(request.server_connection, request.connection) 
+ 
+        elif callable(target): 
+            return _CallableAdapter( 
+                partial(target, **target_params), request.connection 
+            ) 
+ 
+        return None 
+ 
+ 
+class ReversibleRuleRouter(ReversibleRouter, RuleRouter): 
+    """A rule-based router that implements ``reverse_url`` method. 
+ 
+    Each rule added to this router may have a ``name`` attribute that can be 
+    used to reconstruct an original uri. The actual reconstruction takes place 
+    in a rule's matcher (see `Matcher.reverse`). 
+    """ 
+ 
+    def __init__(self, rules=None): 
+        self.named_rules = {}  # type: typing.Dict[str] 
+        super(ReversibleRuleRouter, self).__init__(rules) 
+ 
+    def process_rule(self, rule): 
+        rule = super(ReversibleRuleRouter, self).process_rule(rule) 
+ 
+        if rule.name: 
+            if rule.name in self.named_rules: 
+                app_log.warning( 
+                    "Multiple handlers named %s; replacing previous value", 
+                    rule.name) 
+            self.named_rules[rule.name] = rule 
+ 
+        return rule 
+ 
+    def reverse_url(self, name, *args): 
+        if name in self.named_rules: 
+            return self.named_rules[name].matcher.reverse(*args) 
+ 
+        for rule in self.rules: 
+            if isinstance(rule.target, ReversibleRouter): 
+                reversed_url = rule.target.reverse_url(name, *args) 
+                if reversed_url is not None: 
+                    return reversed_url 
+ 
+        return None 
+ 
+ 
+class Rule(object): 
+    """A routing rule.""" 
+ 
+    def __init__(self, matcher, target, target_kwargs=None, name=None): 
+        """Constructs a Rule instance. 
+ 
+        :arg Matcher matcher: a `Matcher` instance used for determining 
+            whether the rule should be considered a match for a specific 
+            request. 
+        :arg target: a Rule's target (typically a ``RequestHandler`` or 
+            `~.httputil.HTTPServerConnectionDelegate` subclass or even a nested `Router`, 
+            depending on routing implementation). 
+        :arg dict target_kwargs: a dict of parameters that can be useful 
+            at the moment of target instantiation (for example, ``status_code`` 
+            for a ``RequestHandler`` subclass). They end up in 
+            ``target_params['target_kwargs']`` of `RuleRouter.get_target_delegate` 
+            method. 
+        :arg str name: the name of the rule that can be used to find it 
+            in `ReversibleRouter.reverse_url` implementation. 
+        """ 
+        if isinstance(target, str): 
+            # import the Module and instantiate the class 
+            # Must be a fully qualified name (module.ClassName) 
+            target = import_object(target) 
+ 
+        self.matcher = matcher  # type: Matcher 
+        self.target = target 
+        self.target_kwargs = target_kwargs if target_kwargs else {} 
+        self.name = name 
+ 
+    def reverse(self, *args): 
+        return self.matcher.reverse(*args) 
+ 
+    def __repr__(self): 
+        return '%s(%r, %s, kwargs=%r, name=%r)' % \ 
+               (self.__class__.__name__, self.matcher, 
+                self.target, self.target_kwargs, self.name) 
+ 
+ 
+class Matcher(object): 
+    """Represents a matcher for request features.""" 
+ 
+    def match(self, request): 
+        """Matches current instance against the request. 
+ 
+        :arg httputil.HTTPServerRequest request: current HTTP request 
+        :returns: a dict of parameters to be passed to the target handler 
+            (for example, ``handler_kwargs``, ``path_args``, ``path_kwargs`` 
+            can be passed for proper `~.web.RequestHandler` instantiation). 
+            An empty dict is a valid (and common) return value to indicate a match 
+            when the argument-passing features are not used. 
+            ``None`` must be returned to indicate that there is no match.""" 
+        raise NotImplementedError() 
+ 
+    def reverse(self, *args): 
+        """Reconstructs full url from matcher instance and additional arguments.""" 
+        return None 
+ 
+ 
+class AnyMatches(Matcher): 
+    """Matches any request.""" 
+ 
+    def match(self, request): 
+        return {} 
+ 
+ 
+class HostMatches(Matcher): 
+    """Matches requests from hosts specified by ``host_pattern`` regex.""" 
+ 
+    def __init__(self, host_pattern): 
+        if isinstance(host_pattern, basestring_type): 
+            if not host_pattern.endswith("$"): 
+                host_pattern += "$" 
+            self.host_pattern = re.compile(host_pattern) 
+        else: 
+            self.host_pattern = host_pattern 
+ 
+    def match(self, request): 
+        if self.host_pattern.match(request.host_name): 
+            return {} 
+ 
+        return None 
+ 
+ 
+class DefaultHostMatches(Matcher): 
+    """Matches requests from host that is equal to application's default_host. 
+    Always returns no match if ``X-Real-Ip`` header is present. 
+    """ 
+ 
+    def __init__(self, application, host_pattern): 
+        self.application = application 
+        self.host_pattern = host_pattern 
+ 
+    def match(self, request): 
+        # Look for default host if not behind load balancer (for debugging) 
+        if "X-Real-Ip" not in request.headers: 
+            if self.host_pattern.match(self.application.default_host): 
+                return {} 
+        return None 
+ 
+ 
+class PathMatches(Matcher): 
+    """Matches requests with paths specified by ``path_pattern`` regex.""" 
+ 
+    def __init__(self, path_pattern): 
+        if isinstance(path_pattern, basestring_type): 
+            if not path_pattern.endswith('$'): 
+                path_pattern += '$' 
+            self.regex = re.compile(path_pattern) 
+        else: 
+            self.regex = path_pattern 
+ 
+        assert len(self.regex.groupindex) in (0, self.regex.groups), \ 
+            ("groups in url regexes must either be all named or all " 
+             "positional: %r" % self.regex.pattern) 
+ 
+        self._path, self._group_count = self._find_groups() 
+ 
+    def match(self, request): 
+        match = self.regex.match(request.path) 
+        if match is None: 
+            return None 
+        if not self.regex.groups: 
+            return {} 
+ 
+        path_args, path_kwargs = [], {} 
+ 
+        # Pass matched groups to the handler.  Since 
+        # match.groups() includes both named and 
+        # unnamed groups, we want to use either groups 
+        # or groupdict but not both. 
+        if self.regex.groupindex: 
+            path_kwargs = dict( 
+                (str(k), _unquote_or_none(v)) 
+                for (k, v) in match.groupdict().items()) 
+        else: 
+            path_args = [_unquote_or_none(s) for s in match.groups()] 
+ 
+        return dict(path_args=path_args, path_kwargs=path_kwargs) 
+ 
+    def reverse(self, *args): 
+        if self._path is None: 
+            raise ValueError("Cannot reverse url regex " + self.regex.pattern) 
+        assert len(args) == self._group_count, "required number of arguments " \ 
+                                               "not found" 
+        if not len(args): 
+            return self._path 
+        converted_args = [] 
+        for a in args: 
+            if not isinstance(a, (unicode_type, bytes)): 
+                a = str(a) 
+            converted_args.append(url_escape(utf8(a), plus=False)) 
+        return self._path % tuple(converted_args) 
+ 
+    def _find_groups(self): 
+        """Returns a tuple (reverse string, group count) for a url. 
+ 
+        For example: Given the url pattern /([0-9]{4})/([a-z-]+)/, this method 
+        would return ('/%s/%s/', 2). 
+        """ 
+        pattern = self.regex.pattern 
+        if pattern.startswith('^'): 
+            pattern = pattern[1:] 
+        if pattern.endswith('$'): 
+            pattern = pattern[:-1] 
+ 
+        if self.regex.groups != pattern.count('('): 
+            # The pattern is too complicated for our simplistic matching, 
+            # so we can't support reversing it. 
+            return None, None 
+ 
+        pieces = [] 
+        for fragment in pattern.split('('): 
+            if ')' in fragment: 
+                paren_loc = fragment.index(')') 
+                if paren_loc >= 0: 
+                    pieces.append('%s' + fragment[paren_loc + 1:]) 
+            else: 
+                try: 
+                    unescaped_fragment = re_unescape(fragment) 
+                except ValueError as exc: 
+                    # If we can't unescape part of it, we can't 
+                    # reverse this url. 
+                    return (None, None) 
+                pieces.append(unescaped_fragment) 
+ 
+        return ''.join(pieces), self.regex.groups 
+ 
+ 
+class URLSpec(Rule): 
+    """Specifies mappings between URLs and handlers. 
+ 
+    .. versionchanged: 4.5 
+       `URLSpec` is now a subclass of a `Rule` with `PathMatches` matcher and is preserved for 
+       backwards compatibility. 
+    """ 
+    def __init__(self, pattern, handler, kwargs=None, name=None): 
+        """Parameters: 
+ 
+        * ``pattern``: Regular expression to be matched. Any capturing 
+          groups in the regex will be passed in to the handler's 
+          get/post/etc methods as arguments (by keyword if named, by 
+          position if unnamed. Named and unnamed capturing groups may 
+          may not be mixed in the same rule). 
+ 
+        * ``handler``: `~.web.RequestHandler` subclass to be invoked. 
+ 
+        * ``kwargs`` (optional): A dictionary of additional arguments 
+          to be passed to the handler's constructor. 
+ 
+        * ``name`` (optional): A name for this handler.  Used by 
+          `~.web.Application.reverse_url`. 
+ 
+        """ 
+        super(URLSpec, self).__init__(PathMatches(pattern), handler, kwargs, name) 
+ 
+        self.regex = self.matcher.regex 
+        self.handler_class = self.target 
+        self.kwargs = kwargs 
+ 
+    def __repr__(self): 
+        return '%s(%r, %s, kwargs=%r, name=%r)' % \ 
+               (self.__class__.__name__, self.regex.pattern, 
+                self.handler_class, self.kwargs, self.name) 
+ 
+ 
+def _unquote_or_none(s): 
+    """None-safe wrapper around url_unescape to handle unmatched optional 
+    groups correctly. 
+ 
+    Note that args are passed as bytes so the handler can decide what 
+    encoding to use. 
+    """ 
+    if s is None: 
+        return s 
+    return url_unescape(s, encoding=None, plus=False) 
diff --git a/contrib/python/tornado/tornado-4/tornado/simple_httpclient.py b/contrib/python/tornado/tornado-4/tornado/simple_httpclient.py
index 8fb70707f9..6c7767ab3c 100644
--- a/contrib/python/tornado/tornado-4/tornado/simple_httpclient.py
+++ b/contrib/python/tornado/tornado-4/tornado/simple_httpclient.py
@@ -1,567 +1,567 @@
-#!/usr/bin/env python
-from __future__ import absolute_import, division, print_function
-
-from tornado.escape import utf8, _unicode
-from tornado import gen
-from tornado.httpclient import HTTPResponse, HTTPError, AsyncHTTPClient, main, _RequestProxy
-from tornado import httputil
-from tornado.http1connection import HTTP1Connection, HTTP1ConnectionParameters
-from tornado.iostream import StreamClosedError
-from tornado.netutil import Resolver, OverrideResolver, _client_ssl_defaults
-from tornado.log import gen_log
-from tornado import stack_context
-from tornado.tcpclient import TCPClient
-from tornado.util import PY3
-
-import base64
-import collections
-import copy
-import functools
-import re
-import socket
-import sys
-from io import BytesIO
-
-
-if PY3:
-    import urllib.parse as urlparse
-else:
-    import urlparse
-
-try:
-    import ssl
-except ImportError:
-    # ssl is not available on Google App Engine.
-    ssl = None
-
-try:
-    import certifi
-except ImportError:
-    certifi = None
-
-
-def _default_ca_certs():
-    if certifi is None:
-        raise Exception("The 'certifi' package is required to use https "
-                        "in simple_httpclient")
-    return certifi.where()
-
-
-class SimpleAsyncHTTPClient(AsyncHTTPClient):
-    """Non-blocking HTTP client with no external dependencies.
-
-    This class implements an HTTP 1.1 client on top of Tornado's IOStreams.
-    Some features found in the curl-based AsyncHTTPClient are not yet
-    supported.  In particular, proxies are not supported, connections
-    are not reused, and callers cannot select the network interface to be
-    used.
-    """
-    def initialize(self, io_loop, max_clients=10,
-                   hostname_mapping=None, max_buffer_size=104857600,
-                   resolver=None, defaults=None, max_header_size=None,
-                   max_body_size=None):
-        """Creates a AsyncHTTPClient.
-
-        Only a single AsyncHTTPClient instance exists per IOLoop
-        in order to provide limitations on the number of pending connections.
-        ``force_instance=True`` may be used to suppress this behavior.
-
-        Note that because of this implicit reuse, unless ``force_instance``
-        is used, only the first call to the constructor actually uses
-        its arguments. It is recommended to use the ``configure`` method
-        instead of the constructor to ensure that arguments take effect.
-
-        ``max_clients`` is the number of concurrent requests that can be
-        in progress; when this limit is reached additional requests will be
-        queued. Note that time spent waiting in this queue still counts
-        against the ``request_timeout``.
-
-        ``hostname_mapping`` is a dictionary mapping hostnames to IP addresses.
-        It can be used to make local DNS changes when modifying system-wide
-        settings like ``/etc/hosts`` is not possible or desirable (e.g. in
-        unittests).
-
-        ``max_buffer_size`` (default 100MB) is the number of bytes
-        that can be read into memory at once. ``max_body_size``
-        (defaults to ``max_buffer_size``) is the largest response body
-        that the client will accept.  Without a
-        ``streaming_callback``, the smaller of these two limits
-        applies; with a ``streaming_callback`` only ``max_body_size``
-        does.
-
-        .. versionchanged:: 4.2
-           Added the ``max_body_size`` argument.
-        """
-        super(SimpleAsyncHTTPClient, self).initialize(io_loop,
-                                                      defaults=defaults)
-        self.max_clients = max_clients
-        self.queue = collections.deque()
-        self.active = {}
-        self.waiting = {}
-        self.max_buffer_size = max_buffer_size
-        self.max_header_size = max_header_size
-        self.max_body_size = max_body_size
-        # TCPClient could create a Resolver for us, but we have to do it
-        # ourselves to support hostname_mapping.
-        if resolver:
-            self.resolver = resolver
-            self.own_resolver = False
-        else:
-            self.resolver = Resolver(io_loop=io_loop)
-            self.own_resolver = True
-        if hostname_mapping is not None:
-            self.resolver = OverrideResolver(resolver=self.resolver,
-                                             mapping=hostname_mapping)
-        self.tcp_client = TCPClient(resolver=self.resolver, io_loop=io_loop)
-
-    def close(self):
-        super(SimpleAsyncHTTPClient, self).close()
-        if self.own_resolver:
-            self.resolver.close()
-        self.tcp_client.close()
-
-    def fetch_impl(self, request, callback):
-        key = object()
-        self.queue.append((key, request, callback))
-        if not len(self.active) < self.max_clients:
-            timeout_handle = self.io_loop.add_timeout(
-                self.io_loop.time() + min(request.connect_timeout,
-                                          request.request_timeout),
-                functools.partial(self._on_timeout, key, "in request queue"))
-        else:
-            timeout_handle = None
-        self.waiting[key] = (request, callback, timeout_handle)
-        self._process_queue()
-        if self.queue:
-            gen_log.debug("max_clients limit reached, request queued. "
-                          "%d active, %d queued requests." % (
-                              len(self.active), len(self.queue)))
-
-    def _process_queue(self):
-        with stack_context.NullContext():
-            while self.queue and len(self.active) < self.max_clients:
-                key, request, callback = self.queue.popleft()
-                if key not in self.waiting:
-                    continue
-                self._remove_timeout(key)
-                self.active[key] = (request, callback)
-                release_callback = functools.partial(self._release_fetch, key)
-                self._handle_request(request, release_callback, callback)
-
-    def _connection_class(self):
-        return _HTTPConnection
-
-    def _handle_request(self, request, release_callback, final_callback):
-        self._connection_class()(
-            self.io_loop, self, request, release_callback,
-            final_callback, self.max_buffer_size, self.tcp_client,
-            self.max_header_size, self.max_body_size)
-
-    def _release_fetch(self, key):
-        del self.active[key]
-        self._process_queue()
-
-    def _remove_timeout(self, key):
-        if key in self.waiting:
-            request, callback, timeout_handle = self.waiting[key]
-            if timeout_handle is not None:
-                self.io_loop.remove_timeout(timeout_handle)
-            del self.waiting[key]
-
-    def _on_timeout(self, key, info=None):
-        """Timeout callback of request.
-
-        Construct a timeout HTTPResponse when a timeout occurs.
-
-        :arg object key: A simple object to mark the request.
-        :info string key: More detailed timeout information.
-        """
-        request, callback, timeout_handle = self.waiting[key]
-        self.queue.remove((key, request, callback))
-
-        error_message = "Timeout {0}".format(info) if info else "Timeout"
-        timeout_response = HTTPResponse(
-            request, 599, error=HTTPError(599, error_message),
-            request_time=self.io_loop.time() - request.start_time)
-        self.io_loop.add_callback(callback, timeout_response)
-        del self.waiting[key]
-
-
-class _HTTPConnection(httputil.HTTPMessageDelegate):
-    _SUPPORTED_METHODS = set(["GET", "HEAD", "POST", "PUT", "DELETE", "PATCH", "OPTIONS"])
-
-    def __init__(self, io_loop, client, request, release_callback,
-                 final_callback, max_buffer_size, tcp_client,
-                 max_header_size, max_body_size):
-        self.start_time = io_loop.time()
-        self.io_loop = io_loop
-        self.client = client
-        self.request = request
-        self.release_callback = release_callback
-        self.final_callback = final_callback
-        self.max_buffer_size = max_buffer_size
-        self.tcp_client = tcp_client
-        self.max_header_size = max_header_size
-        self.max_body_size = max_body_size
-        self.code = None
-        self.headers = None
-        self.chunks = []
-        self._decompressor = None
-        # Timeout handle returned by IOLoop.add_timeout
-        self._timeout = None
-        self._sockaddr = None
-        with stack_context.ExceptionStackContext(self._handle_exception):
-            self.parsed = urlparse.urlsplit(_unicode(self.request.url))
-            if self.parsed.scheme not in ("http", "https"):
-                raise ValueError("Unsupported url scheme: %s" %
-                                 self.request.url)
-            # urlsplit results have hostname and port results, but they
-            # didn't support ipv6 literals until python 2.7.
-            netloc = self.parsed.netloc
-            if "@" in netloc:
-                userpass, _, netloc = netloc.rpartition("@")
-            host, port = httputil.split_host_and_port(netloc)
-            if port is None:
-                port = 443 if self.parsed.scheme == "https" else 80
-            if re.match(r'^\[.*\]$', host):
-                # raw ipv6 addresses in urls are enclosed in brackets
-                host = host[1:-1]
-            self.parsed_hostname = host  # save final host for _on_connect
-
-            if request.allow_ipv6 is False:
-                af = socket.AF_INET
-            else:
-                af = socket.AF_UNSPEC
-
-            ssl_options = self._get_ssl_options(self.parsed.scheme)
-
-            timeout = min(self.request.connect_timeout, self.request.request_timeout)
-            if timeout:
-                self._timeout = self.io_loop.add_timeout(
-                    self.start_time + timeout,
-                    stack_context.wrap(functools.partial(self._on_timeout, "while connecting")))
-            self.tcp_client.connect(host, port, af=af,
-                                    ssl_options=ssl_options,
-                                    max_buffer_size=self.max_buffer_size,
-                                    callback=self._on_connect)
-
-    def _get_ssl_options(self, scheme):
-        if scheme == "https":
-            if self.request.ssl_options is not None:
-                return self.request.ssl_options
-            # If we are using the defaults, don't construct a
-            # new SSLContext.
-            if (self.request.validate_cert and
-                    self.request.ca_certs is None and
-                    self.request.client_cert is None and
-                    self.request.client_key is None):
-                return _client_ssl_defaults
-            ssl_options = {}
-            if self.request.validate_cert:
-                ssl_options["cert_reqs"] = ssl.CERT_REQUIRED
-            if self.request.ca_certs is not None:
-                ssl_options["ca_certs"] = self.request.ca_certs
-            elif not hasattr(ssl, 'create_default_context'):
-                # When create_default_context is present,
-                # we can omit the "ca_certs" parameter entirely,
-                # which avoids the dependency on "certifi" for py34.
-                ssl_options["ca_certs"] = _default_ca_certs()
-            if self.request.client_key is not None:
-                ssl_options["keyfile"] = self.request.client_key
-            if self.request.client_cert is not None:
-                ssl_options["certfile"] = self.request.client_cert
-
-            # SSL interoperability is tricky.  We want to disable
-            # SSLv2 for security reasons; it wasn't disabled by default
-            # until openssl 1.0.  The best way to do this is to use
-            # the SSL_OP_NO_SSLv2, but that wasn't exposed to python
-            # until 3.2.  Python 2.7 adds the ciphers argument, which
-            # can also be used to disable SSLv2.  As a last resort
-            # on python 2.6, we set ssl_version to TLSv1.  This is
-            # more narrow than we'd like since it also breaks
-            # compatibility with servers configured for SSLv3 only,
-            # but nearly all servers support both SSLv3 and TLSv1:
-            # http://blog.ivanristic.com/2011/09/ssl-survey-protocol-support.html
-            if sys.version_info >= (2, 7):
-                # In addition to disabling SSLv2, we also exclude certain
-                # classes of insecure ciphers.
-                ssl_options["ciphers"] = "DEFAULT:!SSLv2:!EXPORT:!DES"
-            else:
-                # This is really only necessary for pre-1.0 versions
-                # of openssl, but python 2.6 doesn't expose version
-                # information.
-                ssl_options["ssl_version"] = ssl.PROTOCOL_TLSv1
-            return ssl_options
-        return None
-
-    def _on_timeout(self, info=None):
-        """Timeout callback of _HTTPConnection instance.
-
-        Raise a timeout HTTPError when a timeout occurs.
-
-        :info string key: More detailed timeout information.
-        """
-        self._timeout = None
-        error_message = "Timeout {0}".format(info) if info else "Timeout"
-        if self.final_callback is not None:
-            raise HTTPError(599, error_message)
-
-    def _remove_timeout(self):
-        if self._timeout is not None:
-            self.io_loop.remove_timeout(self._timeout)
-            self._timeout = None
-
-    def _on_connect(self, stream):
-        if self.final_callback is None:
-            # final_callback is cleared if we've hit our timeout.
-            stream.close()
-            return
-        self.stream = stream
-        self.stream.set_close_callback(self.on_connection_close)
-        self._remove_timeout()
-        if self.final_callback is None:
-            return
-        if self.request.request_timeout:
-            self._timeout = self.io_loop.add_timeout(
-                self.start_time + self.request.request_timeout,
-                stack_context.wrap(functools.partial(self._on_timeout, "during request")))
-        if (self.request.method not in self._SUPPORTED_METHODS and
-                not self.request.allow_nonstandard_methods):
-            raise KeyError("unknown method %s" % self.request.method)
-        for key in ('network_interface',
-                    'proxy_host', 'proxy_port',
-                    'proxy_username', 'proxy_password',
-                    'proxy_auth_mode'):
-            if getattr(self.request, key, None):
-                raise NotImplementedError('%s not supported' % key)
-        if "Connection" not in self.request.headers:
-            self.request.headers["Connection"] = "close"
-        if "Host" not in self.request.headers:
-            if '@' in self.parsed.netloc:
-                self.request.headers["Host"] = self.parsed.netloc.rpartition('@')[-1]
-            else:
-                self.request.headers["Host"] = self.parsed.netloc
-        username, password = None, None
-        if self.parsed.username is not None:
-            username, password = self.parsed.username, self.parsed.password
-        elif self.request.auth_username is not None:
-            username = self.request.auth_username
-            password = self.request.auth_password or ''
-        if username is not None:
-            if self.request.auth_mode not in (None, "basic"):
-                raise ValueError("unsupported auth_mode %s",
-                                 self.request.auth_mode)
-            auth = utf8(username) + b":" + utf8(password)
-            self.request.headers["Authorization"] = (b"Basic " +
-                                                     base64.b64encode(auth))
-        if self.request.user_agent:
-            self.request.headers["User-Agent"] = self.request.user_agent
-        if not self.request.allow_nonstandard_methods:
-            # Some HTTP methods nearly always have bodies while others
-            # almost never do. Fail in this case unless the user has
-            # opted out of sanity checks with allow_nonstandard_methods.
-            body_expected = self.request.method in ("POST", "PATCH", "PUT")
-            body_present = (self.request.body is not None or
-                            self.request.body_producer is not None)
-            if ((body_expected and not body_present) or
-                    (body_present and not body_expected)):
-                raise ValueError(
-                    'Body must %sbe None for method %s (unless '
-                    'allow_nonstandard_methods is true)' %
-                    ('not ' if body_expected else '', self.request.method))
-        if self.request.expect_100_continue:
-            self.request.headers["Expect"] = "100-continue"
-        if self.request.body is not None:
-            # When body_producer is used the caller is responsible for
-            # setting Content-Length (or else chunked encoding will be used).
-            self.request.headers["Content-Length"] = str(len(
-                self.request.body))
-        if (self.request.method == "POST" and
-                "Content-Type" not in self.request.headers):
-            self.request.headers["Content-Type"] = "application/x-www-form-urlencoded"
-        if self.request.decompress_response:
-            self.request.headers["Accept-Encoding"] = "gzip"
-        req_path = ((self.parsed.path or '/') +
-                    (('?' + self.parsed.query) if self.parsed.query else ''))
-        self.connection = self._create_connection(stream)
-        start_line = httputil.RequestStartLine(self.request.method,
-                                               req_path, '')
-        self.connection.write_headers(start_line, self.request.headers)
-        if self.request.expect_100_continue:
-            self._read_response()
-        else:
-            self._write_body(True)
-
-    def _create_connection(self, stream):
-        stream.set_nodelay(True)
-        connection = HTTP1Connection(
-            stream, True,
-            HTTP1ConnectionParameters(
-                no_keep_alive=True,
-                max_header_size=self.max_header_size,
-                max_body_size=self.max_body_size,
-                decompress=self.request.decompress_response),
-            self._sockaddr)
-        return connection
-
-    def _write_body(self, start_read):
-        if self.request.body is not None:
-            self.connection.write(self.request.body)
-        elif self.request.body_producer is not None:
-            fut = self.request.body_producer(self.connection.write)
-            if fut is not None:
-                fut = gen.convert_yielded(fut)
-
-                def on_body_written(fut):
-                    fut.result()
-                    self.connection.finish()
-                    if start_read:
-                        self._read_response()
-                self.io_loop.add_future(fut, on_body_written)
-                return
-        self.connection.finish()
-        if start_read:
-            self._read_response()
-
-    def _read_response(self):
-        # Ensure that any exception raised in read_response ends up in our
-        # stack context.
-        self.io_loop.add_future(
-            self.connection.read_response(self),
-            lambda f: f.result())
-
-    def _release(self):
-        if self.release_callback is not None:
-            release_callback = self.release_callback
-            self.release_callback = None
-            release_callback()
-
-    def _run_callback(self, response):
-        self._release()
-        if self.final_callback is not None:
-            final_callback = self.final_callback
-            self.final_callback = None
-            self.io_loop.add_callback(final_callback, response)
-
-    def _handle_exception(self, typ, value, tb):
-        if self.final_callback:
-            self._remove_timeout()
-            if isinstance(value, StreamClosedError):
-                if value.real_error is None:
-                    value = HTTPError(599, "Stream closed")
-                else:
-                    value = value.real_error
-            self._run_callback(HTTPResponse(self.request, 599, error=value,
-                                            request_time=self.io_loop.time() - self.start_time,
-                                            ))
-
-            if hasattr(self, "stream"):
-                # TODO: this may cause a StreamClosedError to be raised
-                # by the connection's Future.  Should we cancel the
-                # connection more gracefully?
-                self.stream.close()
-            return True
-        else:
-            # If our callback has already been called, we are probably
-            # catching an exception that is not caused by us but rather
-            # some child of our callback. Rather than drop it on the floor,
-            # pass it along, unless it's just the stream being closed.
-            return isinstance(value, StreamClosedError)
-
-    def on_connection_close(self):
-        if self.final_callback is not None:
-            message = "Connection closed"
-            if self.stream.error:
-                raise self.stream.error
-            try:
-                raise HTTPError(599, message)
-            except HTTPError:
-                self._handle_exception(*sys.exc_info())
-
-    def headers_received(self, first_line, headers):
-        if self.request.expect_100_continue and first_line.code == 100:
-            self._write_body(False)
-            return
-        self.code = first_line.code
-        self.reason = first_line.reason
-        self.headers = headers
-
-        if self._should_follow_redirect():
-            return
-
-        if self.request.header_callback is not None:
-            # Reassemble the start line.
-            self.request.header_callback('%s %s %s\r\n' % first_line)
-            for k, v in self.headers.get_all():
-                self.request.header_callback("%s: %s\r\n" % (k, v))
-            self.request.header_callback('\r\n')
-
-    def _should_follow_redirect(self):
-        return (self.request.follow_redirects and
-                self.request.max_redirects > 0 and
-                self.code in (301, 302, 303, 307, 308))
-
-    def finish(self):
-        data = b''.join(self.chunks)
-        self._remove_timeout()
-        original_request = getattr(self.request, "original_request",
-                                   self.request)
-        if self._should_follow_redirect():
-            assert isinstance(self.request, _RequestProxy)
-            new_request = copy.copy(self.request.request)
-            new_request.url = urlparse.urljoin(self.request.url,
-                                               self.headers["Location"])
-            new_request.max_redirects = self.request.max_redirects - 1
-            del new_request.headers["Host"]
-            # http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.4
-            # Client SHOULD make a GET request after a 303.
-            # According to the spec, 302 should be followed by the same
-            # method as the original request, but in practice browsers
-            # treat 302 the same as 303, and many servers use 302 for
-            # compatibility with pre-HTTP/1.1 user agents which don't
-            # understand the 303 status.
-            if self.code in (302, 303):
-                new_request.method = "GET"
-                new_request.body = None
-                for h in ["Content-Length", "Content-Type",
-                          "Content-Encoding", "Transfer-Encoding"]:
-                    try:
-                        del self.request.headers[h]
-                    except KeyError:
-                        pass
-            new_request.original_request = original_request
-            final_callback = self.final_callback
-            self.final_callback = None
-            self._release()
-            self.client.fetch(new_request, final_callback)
-            self._on_end_request()
-            return
-        if self.request.streaming_callback:
-            buffer = BytesIO()
-        else:
-            buffer = BytesIO(data)  # TODO: don't require one big string?
-        response = HTTPResponse(original_request,
-                                self.code, reason=getattr(self, 'reason', None),
-                                headers=self.headers,
-                                request_time=self.io_loop.time() - self.start_time,
-                                buffer=buffer,
-                                effective_url=self.request.url)
-        self._run_callback(response)
-        self._on_end_request()
-
-    def _on_end_request(self):
-        self.stream.close()
-
-    def data_received(self, chunk):
-        if self._should_follow_redirect():
-            # We're going to follow a redirect so just discard the body.
-            return
-        if self.request.streaming_callback is not None:
-            self.request.streaming_callback(chunk)
-        else:
-            self.chunks.append(chunk)
-
-
-if __name__ == "__main__":
-    AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
-    main()
+#!/usr/bin/env python 
+from __future__ import absolute_import, division, print_function 
+ 
+from tornado.escape import utf8, _unicode 
+from tornado import gen 
+from tornado.httpclient import HTTPResponse, HTTPError, AsyncHTTPClient, main, _RequestProxy 
+from tornado import httputil 
+from tornado.http1connection import HTTP1Connection, HTTP1ConnectionParameters 
+from tornado.iostream import StreamClosedError 
+from tornado.netutil import Resolver, OverrideResolver, _client_ssl_defaults 
+from tornado.log import gen_log 
+from tornado import stack_context 
+from tornado.tcpclient import TCPClient 
+from tornado.util import PY3 
+ 
+import base64 
+import collections 
+import copy 
+import functools 
+import re 
+import socket 
+import sys 
+from io import BytesIO 
+ 
+ 
+if PY3: 
+    import urllib.parse as urlparse 
+else: 
+    import urlparse 
+ 
+try: 
+    import ssl 
+except ImportError: 
+    # ssl is not available on Google App Engine. 
+    ssl = None 
+ 
+try: 
+    import certifi 
+except ImportError: 
+    certifi = None 
+ 
+ 
+def _default_ca_certs(): 
+    if certifi is None: 
+        raise Exception("The 'certifi' package is required to use https " 
+                        "in simple_httpclient") 
+    return certifi.where() 
+ 
+ 
+class SimpleAsyncHTTPClient(AsyncHTTPClient): 
+    """Non-blocking HTTP client with no external dependencies. 
+ 
+    This class implements an HTTP 1.1 client on top of Tornado's IOStreams. 
+    Some features found in the curl-based AsyncHTTPClient are not yet 
+    supported.  In particular, proxies are not supported, connections 
+    are not reused, and callers cannot select the network interface to be 
+    used. 
+    """ 
+    def initialize(self, io_loop, max_clients=10, 
+                   hostname_mapping=None, max_buffer_size=104857600, 
+                   resolver=None, defaults=None, max_header_size=None, 
+                   max_body_size=None): 
+        """Creates a AsyncHTTPClient. 
+ 
+        Only a single AsyncHTTPClient instance exists per IOLoop 
+        in order to provide limitations on the number of pending connections. 
+        ``force_instance=True`` may be used to suppress this behavior. 
+ 
+        Note that because of this implicit reuse, unless ``force_instance`` 
+        is used, only the first call to the constructor actually uses 
+        its arguments. It is recommended to use the ``configure`` method 
+        instead of the constructor to ensure that arguments take effect. 
+ 
+        ``max_clients`` is the number of concurrent requests that can be 
+        in progress; when this limit is reached additional requests will be 
+        queued. Note that time spent waiting in this queue still counts 
+        against the ``request_timeout``. 
+ 
+        ``hostname_mapping`` is a dictionary mapping hostnames to IP addresses. 
+        It can be used to make local DNS changes when modifying system-wide 
+        settings like ``/etc/hosts`` is not possible or desirable (e.g. in 
+        unittests). 
+ 
+        ``max_buffer_size`` (default 100MB) is the number of bytes 
+        that can be read into memory at once. ``max_body_size`` 
+        (defaults to ``max_buffer_size``) is the largest response body 
+        that the client will accept.  Without a 
+        ``streaming_callback``, the smaller of these two limits 
+        applies; with a ``streaming_callback`` only ``max_body_size`` 
+        does. 
+ 
+        .. versionchanged:: 4.2 
+           Added the ``max_body_size`` argument. 
+        """ 
+        super(SimpleAsyncHTTPClient, self).initialize(io_loop, 
+                                                      defaults=defaults) 
+        self.max_clients = max_clients 
+        self.queue = collections.deque() 
+        self.active = {} 
+        self.waiting = {} 
+        self.max_buffer_size = max_buffer_size 
+        self.max_header_size = max_header_size 
+        self.max_body_size = max_body_size 
+        # TCPClient could create a Resolver for us, but we have to do it 
+        # ourselves to support hostname_mapping. 
+        if resolver: 
+            self.resolver = resolver 
+            self.own_resolver = False 
+        else: 
+            self.resolver = Resolver(io_loop=io_loop) 
+            self.own_resolver = True 
+        if hostname_mapping is not None: 
+            self.resolver = OverrideResolver(resolver=self.resolver, 
+                                             mapping=hostname_mapping) 
+        self.tcp_client = TCPClient(resolver=self.resolver, io_loop=io_loop) 
+ 
+    def close(self): 
+        super(SimpleAsyncHTTPClient, self).close() 
+        if self.own_resolver: 
+            self.resolver.close() 
+        self.tcp_client.close() 
+ 
+    def fetch_impl(self, request, callback): 
+        key = object() 
+        self.queue.append((key, request, callback)) 
+        if not len(self.active) < self.max_clients: 
+            timeout_handle = self.io_loop.add_timeout( 
+                self.io_loop.time() + min(request.connect_timeout, 
+                                          request.request_timeout), 
+                functools.partial(self._on_timeout, key, "in request queue")) 
+        else: 
+            timeout_handle = None 
+        self.waiting[key] = (request, callback, timeout_handle) 
+        self._process_queue() 
+        if self.queue: 
+            gen_log.debug("max_clients limit reached, request queued. " 
+                          "%d active, %d queued requests." % ( 
+                              len(self.active), len(self.queue))) 
+ 
+    def _process_queue(self): 
+        with stack_context.NullContext(): 
+            while self.queue and len(self.active) < self.max_clients: 
+                key, request, callback = self.queue.popleft() 
+                if key not in self.waiting: 
+                    continue 
+                self._remove_timeout(key) 
+                self.active[key] = (request, callback) 
+                release_callback = functools.partial(self._release_fetch, key) 
+                self._handle_request(request, release_callback, callback) 
+ 
+    def _connection_class(self): 
+        return _HTTPConnection 
+ 
+    def _handle_request(self, request, release_callback, final_callback): 
+        self._connection_class()( 
+            self.io_loop, self, request, release_callback, 
+            final_callback, self.max_buffer_size, self.tcp_client, 
+            self.max_header_size, self.max_body_size) 
+ 
+    def _release_fetch(self, key): 
+        del self.active[key] 
+        self._process_queue() 
+ 
+    def _remove_timeout(self, key): 
+        if key in self.waiting: 
+            request, callback, timeout_handle = self.waiting[key] 
+            if timeout_handle is not None: 
+                self.io_loop.remove_timeout(timeout_handle) 
+            del self.waiting[key] 
+ 
+    def _on_timeout(self, key, info=None): 
+        """Timeout callback of request. 
+ 
+        Construct a timeout HTTPResponse when a timeout occurs. 
+ 
+        :arg object key: A simple object to mark the request. 
+        :info string key: More detailed timeout information. 
+        """ 
+        request, callback, timeout_handle = self.waiting[key] 
+        self.queue.remove((key, request, callback)) 
+ 
+        error_message = "Timeout {0}".format(info) if info else "Timeout" 
+        timeout_response = HTTPResponse( 
+            request, 599, error=HTTPError(599, error_message), 
+            request_time=self.io_loop.time() - request.start_time) 
+        self.io_loop.add_callback(callback, timeout_response) 
+        del self.waiting[key] 
+ 
+ 
+class _HTTPConnection(httputil.HTTPMessageDelegate): 
+    _SUPPORTED_METHODS = set(["GET", "HEAD", "POST", "PUT", "DELETE", "PATCH", "OPTIONS"]) 
+ 
+    def __init__(self, io_loop, client, request, release_callback, 
+                 final_callback, max_buffer_size, tcp_client, 
+                 max_header_size, max_body_size): 
+        self.start_time = io_loop.time() 
+        self.io_loop = io_loop 
+        self.client = client 
+        self.request = request 
+        self.release_callback = release_callback 
+        self.final_callback = final_callback 
+        self.max_buffer_size = max_buffer_size 
+        self.tcp_client = tcp_client 
+        self.max_header_size = max_header_size 
+        self.max_body_size = max_body_size 
+        self.code = None 
+        self.headers = None 
+        self.chunks = [] 
+        self._decompressor = None 
+        # Timeout handle returned by IOLoop.add_timeout 
+        self._timeout = None 
+        self._sockaddr = None 
+        with stack_context.ExceptionStackContext(self._handle_exception): 
+            self.parsed = urlparse.urlsplit(_unicode(self.request.url)) 
+            if self.parsed.scheme not in ("http", "https"): 
+                raise ValueError("Unsupported url scheme: %s" % 
+                                 self.request.url) 
+            # urlsplit results have hostname and port results, but they 
+            # didn't support ipv6 literals until python 2.7. 
+            netloc = self.parsed.netloc 
+            if "@" in netloc: 
+                userpass, _, netloc = netloc.rpartition("@") 
+            host, port = httputil.split_host_and_port(netloc) 
+            if port is None: 
+                port = 443 if self.parsed.scheme == "https" else 80 
+            if re.match(r'^\[.*\]$', host): 
+                # raw ipv6 addresses in urls are enclosed in brackets 
+                host = host[1:-1] 
+            self.parsed_hostname = host  # save final host for _on_connect 
+ 
+            if request.allow_ipv6 is False: 
+                af = socket.AF_INET 
+            else: 
+                af = socket.AF_UNSPEC 
+ 
+            ssl_options = self._get_ssl_options(self.parsed.scheme) 
+ 
+            timeout = min(self.request.connect_timeout, self.request.request_timeout) 
+            if timeout: 
+                self._timeout = self.io_loop.add_timeout( 
+                    self.start_time + timeout, 
+                    stack_context.wrap(functools.partial(self._on_timeout, "while connecting"))) 
+            self.tcp_client.connect(host, port, af=af, 
+                                    ssl_options=ssl_options, 
+                                    max_buffer_size=self.max_buffer_size, 
+                                    callback=self._on_connect) 
+ 
+    def _get_ssl_options(self, scheme): 
+        if scheme == "https": 
+            if self.request.ssl_options is not None: 
+                return self.request.ssl_options 
+            # If we are using the defaults, don't construct a 
+            # new SSLContext. 
+            if (self.request.validate_cert and 
+                    self.request.ca_certs is None and 
+                    self.request.client_cert is None and 
+                    self.request.client_key is None): 
+                return _client_ssl_defaults 
+            ssl_options = {} 
+            if self.request.validate_cert: 
+                ssl_options["cert_reqs"] = ssl.CERT_REQUIRED 
+            if self.request.ca_certs is not None: 
+                ssl_options["ca_certs"] = self.request.ca_certs 
+            elif not hasattr(ssl, 'create_default_context'): 
+                # When create_default_context is present, 
+                # we can omit the "ca_certs" parameter entirely, 
+                # which avoids the dependency on "certifi" for py34. 
+                ssl_options["ca_certs"] = _default_ca_certs() 
+            if self.request.client_key is not None: 
+                ssl_options["keyfile"] = self.request.client_key 
+            if self.request.client_cert is not None: 
+                ssl_options["certfile"] = self.request.client_cert 
+ 
+            # SSL interoperability is tricky.  We want to disable 
+            # SSLv2 for security reasons; it wasn't disabled by default 
+            # until openssl 1.0.  The best way to do this is to use 
+            # the SSL_OP_NO_SSLv2, but that wasn't exposed to python 
+            # until 3.2.  Python 2.7 adds the ciphers argument, which 
+            # can also be used to disable SSLv2.  As a last resort 
+            # on python 2.6, we set ssl_version to TLSv1.  This is 
+            # more narrow than we'd like since it also breaks 
+            # compatibility with servers configured for SSLv3 only, 
+            # but nearly all servers support both SSLv3 and TLSv1: 
+            # http://blog.ivanristic.com/2011/09/ssl-survey-protocol-support.html 
+            if sys.version_info >= (2, 7): 
+                # In addition to disabling SSLv2, we also exclude certain 
+                # classes of insecure ciphers. 
+                ssl_options["ciphers"] = "DEFAULT:!SSLv2:!EXPORT:!DES" 
+            else: 
+                # This is really only necessary for pre-1.0 versions 
+                # of openssl, but python 2.6 doesn't expose version 
+                # information. 
+                ssl_options["ssl_version"] = ssl.PROTOCOL_TLSv1 
+            return ssl_options 
+        return None 
+ 
+    def _on_timeout(self, info=None): 
+        """Timeout callback of _HTTPConnection instance. 
+ 
+        Raise a timeout HTTPError when a timeout occurs. 
+ 
+        :info string key: More detailed timeout information. 
+        """ 
+        self._timeout = None 
+        error_message = "Timeout {0}".format(info) if info else "Timeout" 
+        if self.final_callback is not None: 
+            raise HTTPError(599, error_message) 
+ 
+    def _remove_timeout(self): 
+        if self._timeout is not None: 
+            self.io_loop.remove_timeout(self._timeout) 
+            self._timeout = None 
+ 
+    def _on_connect(self, stream): 
+        if self.final_callback is None: 
+            # final_callback is cleared if we've hit our timeout. 
+            stream.close() 
+            return 
+        self.stream = stream 
+        self.stream.set_close_callback(self.on_connection_close) 
+        self._remove_timeout() 
+        if self.final_callback is None: 
+            return 
+        if self.request.request_timeout: 
+            self._timeout = self.io_loop.add_timeout( 
+                self.start_time + self.request.request_timeout, 
+                stack_context.wrap(functools.partial(self._on_timeout, "during request"))) 
+        if (self.request.method not in self._SUPPORTED_METHODS and 
+                not self.request.allow_nonstandard_methods): 
+            raise KeyError("unknown method %s" % self.request.method) 
+        for key in ('network_interface', 
+                    'proxy_host', 'proxy_port', 
+                    'proxy_username', 'proxy_password', 
+                    'proxy_auth_mode'): 
+            if getattr(self.request, key, None): 
+                raise NotImplementedError('%s not supported' % key) 
+        if "Connection" not in self.request.headers: 
+            self.request.headers["Connection"] = "close" 
+        if "Host" not in self.request.headers: 
+            if '@' in self.parsed.netloc: 
+                self.request.headers["Host"] = self.parsed.netloc.rpartition('@')[-1] 
+            else: 
+                self.request.headers["Host"] = self.parsed.netloc 
+        username, password = None, None 
+        if self.parsed.username is not None: 
+            username, password = self.parsed.username, self.parsed.password 
+        elif self.request.auth_username is not None: 
+            username = self.request.auth_username 
+            password = self.request.auth_password or '' 
+        if username is not None: 
+            if self.request.auth_mode not in (None, "basic"): 
+                raise ValueError("unsupported auth_mode %s", 
+                                 self.request.auth_mode) 
+            auth = utf8(username) + b":" + utf8(password) 
+            self.request.headers["Authorization"] = (b"Basic " + 
+                                                     base64.b64encode(auth)) 
+        if self.request.user_agent: 
+            self.request.headers["User-Agent"] = self.request.user_agent 
+        if not self.request.allow_nonstandard_methods: 
+            # Some HTTP methods nearly always have bodies while others 
+            # almost never do. Fail in this case unless the user has 
+            # opted out of sanity checks with allow_nonstandard_methods. 
+            body_expected = self.request.method in ("POST", "PATCH", "PUT") 
+            body_present = (self.request.body is not None or 
+                            self.request.body_producer is not None) 
+            if ((body_expected and not body_present) or 
+                    (body_present and not body_expected)): 
+                raise ValueError( 
+                    'Body must %sbe None for method %s (unless ' 
+                    'allow_nonstandard_methods is true)' % 
+                    ('not ' if body_expected else '', self.request.method)) 
+        if self.request.expect_100_continue: 
+            self.request.headers["Expect"] = "100-continue" 
+        if self.request.body is not None: 
+            # When body_producer is used the caller is responsible for 
+            # setting Content-Length (or else chunked encoding will be used). 
+            self.request.headers["Content-Length"] = str(len( 
+                self.request.body)) 
+        if (self.request.method == "POST" and 
+                "Content-Type" not in self.request.headers): 
+            self.request.headers["Content-Type"] = "application/x-www-form-urlencoded" 
+        if self.request.decompress_response: 
+            self.request.headers["Accept-Encoding"] = "gzip" 
+        req_path = ((self.parsed.path or '/') + 
+                    (('?' + self.parsed.query) if self.parsed.query else '')) 
+        self.connection = self._create_connection(stream) 
+        start_line = httputil.RequestStartLine(self.request.method, 
+                                               req_path, '') 
+        self.connection.write_headers(start_line, self.request.headers) 
+        if self.request.expect_100_continue: 
+            self._read_response() 
+        else: 
+            self._write_body(True) 
+ 
+    def _create_connection(self, stream): 
+        stream.set_nodelay(True) 
+        connection = HTTP1Connection( 
+            stream, True, 
+            HTTP1ConnectionParameters( 
+                no_keep_alive=True, 
+                max_header_size=self.max_header_size, 
+                max_body_size=self.max_body_size, 
+                decompress=self.request.decompress_response), 
+            self._sockaddr) 
+        return connection 
+ 
+    def _write_body(self, start_read): 
+        if self.request.body is not None: 
+            self.connection.write(self.request.body) 
+        elif self.request.body_producer is not None: 
+            fut = self.request.body_producer(self.connection.write) 
+            if fut is not None: 
+                fut = gen.convert_yielded(fut) 
+ 
+                def on_body_written(fut): 
+                    fut.result() 
+                    self.connection.finish() 
+                    if start_read: 
+                        self._read_response() 
+                self.io_loop.add_future(fut, on_body_written) 
+                return 
+        self.connection.finish() 
+        if start_read: 
+            self._read_response() 
+ 
+    def _read_response(self): 
+        # Ensure that any exception raised in read_response ends up in our 
+        # stack context. 
+        self.io_loop.add_future( 
+            self.connection.read_response(self), 
+            lambda f: f.result()) 
+ 
+    def _release(self): 
+        if self.release_callback is not None: 
+            release_callback = self.release_callback 
+            self.release_callback = None 
+            release_callback() 
+ 
+    def _run_callback(self, response): 
+        self._release() 
+        if self.final_callback is not None: 
+            final_callback = self.final_callback 
+            self.final_callback = None 
+            self.io_loop.add_callback(final_callback, response) 
+ 
+    def _handle_exception(self, typ, value, tb): 
+        if self.final_callback: 
+            self._remove_timeout() 
+            if isinstance(value, StreamClosedError): 
+                if value.real_error is None: 
+                    value = HTTPError(599, "Stream closed") 
+                else: 
+                    value = value.real_error 
+            self._run_callback(HTTPResponse(self.request, 599, error=value, 
+                                            request_time=self.io_loop.time() - self.start_time, 
+                                            )) 
+ 
+            if hasattr(self, "stream"): 
+                # TODO: this may cause a StreamClosedError to be raised 
+                # by the connection's Future.  Should we cancel the 
+                # connection more gracefully? 
+                self.stream.close() 
+            return True 
+        else: 
+            # If our callback has already been called, we are probably 
+            # catching an exception that is not caused by us but rather 
+            # some child of our callback. Rather than drop it on the floor, 
+            # pass it along, unless it's just the stream being closed. 
+            return isinstance(value, StreamClosedError) 
+ 
+    def on_connection_close(self): 
+        if self.final_callback is not None: 
+            message = "Connection closed" 
+            if self.stream.error: 
+                raise self.stream.error 
+            try: 
+                raise HTTPError(599, message) 
+            except HTTPError: 
+                self._handle_exception(*sys.exc_info()) 
+ 
+    def headers_received(self, first_line, headers): 
+        if self.request.expect_100_continue and first_line.code == 100: 
+            self._write_body(False) 
+            return 
+        self.code = first_line.code 
+        self.reason = first_line.reason 
+        self.headers = headers 
+ 
+        if self._should_follow_redirect(): 
+            return 
+ 
+        if self.request.header_callback is not None: 
+            # Reassemble the start line. 
+            self.request.header_callback('%s %s %s\r\n' % first_line) 
+            for k, v in self.headers.get_all(): 
+                self.request.header_callback("%s: %s\r\n" % (k, v)) 
+            self.request.header_callback('\r\n') 
+ 
+    def _should_follow_redirect(self): 
+        return (self.request.follow_redirects and 
+                self.request.max_redirects > 0 and 
+                self.code in (301, 302, 303, 307, 308)) 
+ 
+    def finish(self): 
+        data = b''.join(self.chunks) 
+        self._remove_timeout() 
+        original_request = getattr(self.request, "original_request", 
+                                   self.request) 
+        if self._should_follow_redirect(): 
+            assert isinstance(self.request, _RequestProxy) 
+            new_request = copy.copy(self.request.request) 
+            new_request.url = urlparse.urljoin(self.request.url, 
+                                               self.headers["Location"]) 
+            new_request.max_redirects = self.request.max_redirects - 1 
+            del new_request.headers["Host"] 
+            # http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.4 
+            # Client SHOULD make a GET request after a 303. 
+            # According to the spec, 302 should be followed by the same 
+            # method as the original request, but in practice browsers 
+            # treat 302 the same as 303, and many servers use 302 for 
+            # compatibility with pre-HTTP/1.1 user agents which don't 
+            # understand the 303 status. 
+            if self.code in (302, 303): 
+                new_request.method = "GET" 
+                new_request.body = None 
+                for h in ["Content-Length", "Content-Type", 
+                          "Content-Encoding", "Transfer-Encoding"]: 
+                    try: 
+                        del self.request.headers[h] 
+                    except KeyError: 
+                        pass 
+            new_request.original_request = original_request 
+            final_callback = self.final_callback 
+            self.final_callback = None 
+            self._release() 
+            self.client.fetch(new_request, final_callback) 
+            self._on_end_request() 
+            return 
+        if self.request.streaming_callback: 
+            buffer = BytesIO() 
+        else: 
+            buffer = BytesIO(data)  # TODO: don't require one big string? 
+        response = HTTPResponse(original_request, 
+                                self.code, reason=getattr(self, 'reason', None), 
+                                headers=self.headers, 
+                                request_time=self.io_loop.time() - self.start_time, 
+                                buffer=buffer, 
+                                effective_url=self.request.url) 
+        self._run_callback(response) 
+        self._on_end_request() 
+ 
+    def _on_end_request(self): 
+        self.stream.close() 
+ 
+    def data_received(self, chunk): 
+        if self._should_follow_redirect(): 
+            # We're going to follow a redirect so just discard the body. 
+            return 
+        if self.request.streaming_callback is not None: 
+            self.request.streaming_callback(chunk) 
+        else: 
+            self.chunks.append(chunk) 
+ 
+ 
+if __name__ == "__main__": 
+    AsyncHTTPClient.configure(SimpleAsyncHTTPClient) 
+    main() 
diff --git a/contrib/python/tornado/tornado-4/tornado/speedups.c b/contrib/python/tornado/tornado-4/tornado/speedups.c
index c59bda0092..bea15523ff 100644
--- a/contrib/python/tornado/tornado-4/tornado/speedups.c
+++ b/contrib/python/tornado/tornado-4/tornado/speedups.c
@@ -1,52 +1,52 @@
-#define PY_SSIZE_T_CLEAN
-#include <Python.h>
-
-static PyObject* websocket_mask(PyObject* self, PyObject* args) {
-    const char* mask;
-    Py_ssize_t mask_len;
-    const char* data;
-    Py_ssize_t data_len;
-    Py_ssize_t i;
-    PyObject* result;
-    char* buf;
-
-    if (!PyArg_ParseTuple(args, "s#s#", &mask, &mask_len, &data, &data_len)) {
-        return NULL;
-    }
-
-    result = PyBytes_FromStringAndSize(NULL, data_len);
-    if (!result) {
-        return NULL;
-    }
-    buf = PyBytes_AsString(result);
-    for (i = 0; i < data_len; i++) {
-        buf[i] = data[i] ^ mask[i % 4];
-    }
-
-    return result;
-}
-
-static PyMethodDef methods[] = {
-    {"websocket_mask",  websocket_mask, METH_VARARGS, ""},
-    {NULL, NULL, 0, NULL}
-};
-
-#if PY_MAJOR_VERSION >= 3
-static struct PyModuleDef speedupsmodule = {
-   PyModuleDef_HEAD_INIT,
-   "speedups",
-   NULL,
-   -1,
-   methods
-};
-
-PyMODINIT_FUNC
-PyInit_speedups(void) {
-    return PyModule_Create(&speedupsmodule);
-}
-#else  // Python 2.x
-PyMODINIT_FUNC
-initspeedups(void) {
-    Py_InitModule("tornado.speedups", methods);
-}
-#endif
+#define PY_SSIZE_T_CLEAN 
+#include <Python.h> 
+ 
+static PyObject* websocket_mask(PyObject* self, PyObject* args) { 
+    const char* mask; 
+    Py_ssize_t mask_len; 
+    const char* data; 
+    Py_ssize_t data_len; 
+    Py_ssize_t i; 
+    PyObject* result; 
+    char* buf; 
+ 
+    if (!PyArg_ParseTuple(args, "s#s#", &mask, &mask_len, &data, &data_len)) { 
+        return NULL; 
+    } 
+ 
+    result = PyBytes_FromStringAndSize(NULL, data_len); 
+    if (!result) { 
+        return NULL; 
+    } 
+    buf = PyBytes_AsString(result); 
+    for (i = 0; i < data_len; i++) { 
+        buf[i] = data[i] ^ mask[i % 4]; 
+    } 
+ 
+    return result; 
+} 
+ 
+static PyMethodDef methods[] = { 
+    {"websocket_mask",  websocket_mask, METH_VARARGS, ""}, 
+    {NULL, NULL, 0, NULL} 
+}; 
+ 
+#if PY_MAJOR_VERSION >= 3 
+static struct PyModuleDef speedupsmodule = { 
+   PyModuleDef_HEAD_INIT, 
+   "speedups", 
+   NULL, 
+   -1, 
+   methods 
+}; 
+ 
+PyMODINIT_FUNC 
+PyInit_speedups(void) { 
+    return PyModule_Create(&speedupsmodule); 
+} 
+#else  // Python 2.x 
+PyMODINIT_FUNC 
+initspeedups(void) { 
+    Py_InitModule("tornado.speedups", methods); 
+} 
+#endif 
diff --git a/contrib/python/tornado/tornado-4/tornado/stack_context.py b/contrib/python/tornado/tornado-4/tornado/stack_context.py
index 61ae51f4eb..3081121329 100644
--- a/contrib/python/tornado/tornado-4/tornado/stack_context.py
+++ b/contrib/python/tornado/tornado-4/tornado/stack_context.py
@@ -1,390 +1,390 @@
-#!/usr/bin/env python
-#
-# Copyright 2010 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""`StackContext` allows applications to maintain threadlocal-like state
-that follows execution as it moves to other execution contexts.
-
-The motivating examples are to eliminate the need for explicit
-``async_callback`` wrappers (as in `tornado.web.RequestHandler`), and to
-allow some additional context to be kept for logging.
-
-This is slightly magic, but it's an extension of the idea that an
-exception handler is a kind of stack-local state and when that stack
-is suspended and resumed in a new context that state needs to be
-preserved.  `StackContext` shifts the burden of restoring that state
-from each call site (e.g.  wrapping each `.AsyncHTTPClient` callback
-in ``async_callback``) to the mechanisms that transfer control from
-one context to another (e.g. `.AsyncHTTPClient` itself, `.IOLoop`,
-thread pools, etc).
-
-Example usage::
-
-    @contextlib.contextmanager
-    def die_on_error():
-        try:
-            yield
-        except Exception:
-            logging.error("exception in asynchronous operation",exc_info=True)
-            sys.exit(1)
-
-    with StackContext(die_on_error):
-        # Any exception thrown here *or in callback and its descendants*
-        # will cause the process to exit instead of spinning endlessly
-        # in the ioloop.
-        http_client.fetch(url, callback)
-    ioloop.start()
-
-Most applications shouldn't have to work with `StackContext` directly.
-Here are a few rules of thumb for when it's necessary:
-
-* If you're writing an asynchronous library that doesn't rely on a
-  stack_context-aware library like `tornado.ioloop` or `tornado.iostream`
-  (for example, if you're writing a thread pool), use
-  `.stack_context.wrap()` before any asynchronous operations to capture the
-  stack context from where the operation was started.
-
-* If you're writing an asynchronous library that has some shared
-  resources (such as a connection pool), create those shared resources
-  within a ``with stack_context.NullContext():`` block.  This will prevent
-  ``StackContexts`` from leaking from one request to another.
-
-* If you want to write something like an exception handler that will
-  persist across asynchronous calls, create a new `StackContext` (or
-  `ExceptionStackContext`), and make your asynchronous calls in a ``with``
-  block that references your `StackContext`.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import sys
-import threading
-
-from tornado.util import raise_exc_info
-
-
-class StackContextInconsistentError(Exception):
-    pass
-
-
-class _State(threading.local):
-    def __init__(self):
-        self.contexts = (tuple(), None)
-
-
-_state = _State()
-
-
-class StackContext(object):
-    """Establishes the given context as a StackContext that will be transferred.
-
-    Note that the parameter is a callable that returns a context
-    manager, not the context itself.  That is, where for a
-    non-transferable context manager you would say::
-
-      with my_context():
-
-    StackContext takes the function itself rather than its result::
-
-      with StackContext(my_context):
-
-    The result of ``with StackContext() as cb:`` is a deactivation
-    callback.  Run this callback when the StackContext is no longer
-    needed to ensure that it is not propagated any further (note that
-    deactivating a context does not affect any instances of that
-    context that are currently pending).  This is an advanced feature
-    and not necessary in most applications.
-    """
-    def __init__(self, context_factory):
-        self.context_factory = context_factory
-        self.contexts = []
-        self.active = True
-
-    def _deactivate(self):
-        self.active = False
-
-    # StackContext protocol
-    def enter(self):
-        context = self.context_factory()
-        self.contexts.append(context)
-        context.__enter__()
-
-    def exit(self, type, value, traceback):
-        context = self.contexts.pop()
-        context.__exit__(type, value, traceback)
-
-    # Note that some of this code is duplicated in ExceptionStackContext
-    # below.  ExceptionStackContext is more common and doesn't need
-    # the full generality of this class.
-    def __enter__(self):
-        self.old_contexts = _state.contexts
-        self.new_contexts = (self.old_contexts[0] + (self,), self)
-        _state.contexts = self.new_contexts
-
-        try:
-            self.enter()
-        except:
-            _state.contexts = self.old_contexts
-            raise
-
-        return self._deactivate
-
-    def __exit__(self, type, value, traceback):
-        try:
-            self.exit(type, value, traceback)
-        finally:
-            final_contexts = _state.contexts
-            _state.contexts = self.old_contexts
-
-            # Generator coroutines and with-statements with non-local
-            # effects interact badly.  Check here for signs of
-            # the stack getting out of sync.
-            # Note that this check comes after restoring _state.context
-            # so that if it fails things are left in a (relatively)
-            # consistent state.
-            if final_contexts is not self.new_contexts:
-                raise StackContextInconsistentError(
-                    'stack_context inconsistency (may be caused by yield '
-                    'within a "with StackContext" block)')
-
-            # Break up a reference to itself to allow for faster GC on CPython.
-            self.new_contexts = None
-
-
-class ExceptionStackContext(object):
-    """Specialization of StackContext for exception handling.
-
-    The supplied ``exception_handler`` function will be called in the
-    event of an uncaught exception in this context.  The semantics are
-    similar to a try/finally clause, and intended use cases are to log
-    an error, close a socket, or similar cleanup actions.  The
-    ``exc_info`` triple ``(type, value, traceback)`` will be passed to the
-    exception_handler function.
-
-    If the exception handler returns true, the exception will be
-    consumed and will not be propagated to other exception handlers.
-    """
-    def __init__(self, exception_handler):
-        self.exception_handler = exception_handler
-        self.active = True
-
-    def _deactivate(self):
-        self.active = False
-
-    def exit(self, type, value, traceback):
-        if type is not None:
-            return self.exception_handler(type, value, traceback)
-
-    def __enter__(self):
-        self.old_contexts = _state.contexts
-        self.new_contexts = (self.old_contexts[0], self)
-        _state.contexts = self.new_contexts
-
-        return self._deactivate
-
-    def __exit__(self, type, value, traceback):
-        try:
-            if type is not None:
-                return self.exception_handler(type, value, traceback)
-        finally:
-            final_contexts = _state.contexts
-            _state.contexts = self.old_contexts
-
-            if final_contexts is not self.new_contexts:
-                raise StackContextInconsistentError(
-                    'stack_context inconsistency (may be caused by yield '
-                    'within a "with StackContext" block)')
-
-            # Break up a reference to itself to allow for faster GC on CPython.
-            self.new_contexts = None
-
-
-class NullContext(object):
-    """Resets the `StackContext`.
-
-    Useful when creating a shared resource on demand (e.g. an
-    `.AsyncHTTPClient`) where the stack that caused the creating is
-    not relevant to future operations.
-    """
-    def __enter__(self):
-        self.old_contexts = _state.contexts
-        _state.contexts = (tuple(), None)
-
-    def __exit__(self, type, value, traceback):
-        _state.contexts = self.old_contexts
-
-
-def _remove_deactivated(contexts):
-    """Remove deactivated handlers from the chain"""
-    # Clean ctx handlers
-    stack_contexts = tuple([h for h in contexts[0] if h.active])
-
-    # Find new head
-    head = contexts[1]
-    while head is not None and not head.active:
-        head = head.old_contexts[1]
-
-    # Process chain
-    ctx = head
-    while ctx is not None:
-        parent = ctx.old_contexts[1]
-
-        while parent is not None:
-            if parent.active:
-                break
-            ctx.old_contexts = parent.old_contexts
-            parent = parent.old_contexts[1]
-
-        ctx = parent
-
-    return (stack_contexts, head)
-
-
-def wrap(fn):
-    """Returns a callable object that will restore the current `StackContext`
-    when executed.
-
-    Use this whenever saving a callback to be executed later in a
-    different execution context (either in a different thread or
-    asynchronously in the same thread).
-    """
-    # Check if function is already wrapped
-    if fn is None or hasattr(fn, '_wrapped'):
-        return fn
-
-    # Capture current stack head
-    # TODO: Any other better way to store contexts and update them in wrapped function?
-    cap_contexts = [_state.contexts]
-
-    if not cap_contexts[0][0] and not cap_contexts[0][1]:
-        # Fast path when there are no active contexts.
-        def null_wrapper(*args, **kwargs):
-            try:
-                current_state = _state.contexts
-                _state.contexts = cap_contexts[0]
-                return fn(*args, **kwargs)
-            finally:
-                _state.contexts = current_state
-        null_wrapper._wrapped = True
-        return null_wrapper
-
-    def wrapped(*args, **kwargs):
-        ret = None
-        try:
-            # Capture old state
-            current_state = _state.contexts
-
-            # Remove deactivated items
-            cap_contexts[0] = contexts = _remove_deactivated(cap_contexts[0])
-
-            # Force new state
-            _state.contexts = contexts
-
-            # Current exception
-            exc = (None, None, None)
-            top = None
-
-            # Apply stack contexts
-            last_ctx = 0
-            stack = contexts[0]
-
-            # Apply state
-            for n in stack:
-                try:
-                    n.enter()
-                    last_ctx += 1
-                except:
-                    # Exception happened. Record exception info and store top-most handler
-                    exc = sys.exc_info()
-                    top = n.old_contexts[1]
-
-            # Execute callback if no exception happened while restoring state
-            if top is None:
-                try:
-                    ret = fn(*args, **kwargs)
-                except:
-                    exc = sys.exc_info()
-                    top = contexts[1]
-
-            # If there was exception, try to handle it by going through the exception chain
-            if top is not None:
-                exc = _handle_exception(top, exc)
-            else:
-                # Otherwise take shorter path and run stack contexts in reverse order
-                while last_ctx > 0:
-                    last_ctx -= 1
-                    c = stack[last_ctx]
-
-                    try:
-                        c.exit(*exc)
-                    except:
-                        exc = sys.exc_info()
-                        top = c.old_contexts[1]
-                        break
-                else:
-                    top = None
-
-                # If if exception happened while unrolling, take longer exception handler path
-                if top is not None:
-                    exc = _handle_exception(top, exc)
-
-            # If exception was not handled, raise it
-            if exc != (None, None, None):
-                raise_exc_info(exc)
-        finally:
-            _state.contexts = current_state
-        return ret
-
-    wrapped._wrapped = True
-    return wrapped
-
-
-def _handle_exception(tail, exc):
-    while tail is not None:
-        try:
-            if tail.exit(*exc):
-                exc = (None, None, None)
-        except:
-            exc = sys.exc_info()
-
-        tail = tail.old_contexts[1]
-
-    return exc
-
-
-def run_with_stack_context(context, func):
-    """Run a coroutine ``func`` in the given `StackContext`.
-
-    It is not safe to have a ``yield`` statement within a ``with StackContext``
-    block, so it is difficult to use stack context with `.gen.coroutine`.
-    This helper function runs the function in the correct context while
-    keeping the ``yield`` and ``with`` statements syntactically separate.
-
-    Example::
-
-        @gen.coroutine
-        def incorrect():
-            with StackContext(ctx):
-                # ERROR: this will raise StackContextInconsistentError
-                yield other_coroutine()
-
-        @gen.coroutine
-        def correct():
-            yield run_with_stack_context(StackContext(ctx), other_coroutine)
-
-    .. versionadded:: 3.1
-    """
-    with context:
-        return func()
+#!/usr/bin/env python 
+# 
+# Copyright 2010 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""`StackContext` allows applications to maintain threadlocal-like state 
+that follows execution as it moves to other execution contexts. 
+ 
+The motivating examples are to eliminate the need for explicit 
+``async_callback`` wrappers (as in `tornado.web.RequestHandler`), and to 
+allow some additional context to be kept for logging. 
+ 
+This is slightly magic, but it's an extension of the idea that an 
+exception handler is a kind of stack-local state and when that stack 
+is suspended and resumed in a new context that state needs to be 
+preserved.  `StackContext` shifts the burden of restoring that state 
+from each call site (e.g.  wrapping each `.AsyncHTTPClient` callback 
+in ``async_callback``) to the mechanisms that transfer control from 
+one context to another (e.g. `.AsyncHTTPClient` itself, `.IOLoop`, 
+thread pools, etc). 
+ 
+Example usage:: 
+ 
+    @contextlib.contextmanager 
+    def die_on_error(): 
+        try: 
+            yield 
+        except Exception: 
+            logging.error("exception in asynchronous operation",exc_info=True) 
+            sys.exit(1) 
+ 
+    with StackContext(die_on_error): 
+        # Any exception thrown here *or in callback and its descendants* 
+        # will cause the process to exit instead of spinning endlessly 
+        # in the ioloop. 
+        http_client.fetch(url, callback) 
+    ioloop.start() 
+ 
+Most applications shouldn't have to work with `StackContext` directly. 
+Here are a few rules of thumb for when it's necessary: 
+ 
+* If you're writing an asynchronous library that doesn't rely on a 
+  stack_context-aware library like `tornado.ioloop` or `tornado.iostream` 
+  (for example, if you're writing a thread pool), use 
+  `.stack_context.wrap()` before any asynchronous operations to capture the 
+  stack context from where the operation was started. 
+ 
+* If you're writing an asynchronous library that has some shared 
+  resources (such as a connection pool), create those shared resources 
+  within a ``with stack_context.NullContext():`` block.  This will prevent 
+  ``StackContexts`` from leaking from one request to another. 
+ 
+* If you want to write something like an exception handler that will 
+  persist across asynchronous calls, create a new `StackContext` (or 
+  `ExceptionStackContext`), and make your asynchronous calls in a ``with`` 
+  block that references your `StackContext`. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import sys 
+import threading 
+ 
+from tornado.util import raise_exc_info 
+ 
+ 
+class StackContextInconsistentError(Exception): 
+    pass 
+ 
+ 
+class _State(threading.local): 
+    def __init__(self): 
+        self.contexts = (tuple(), None) 
+ 
+ 
+_state = _State() 
+ 
+ 
+class StackContext(object): 
+    """Establishes the given context as a StackContext that will be transferred. 
+ 
+    Note that the parameter is a callable that returns a context 
+    manager, not the context itself.  That is, where for a 
+    non-transferable context manager you would say:: 
+ 
+      with my_context(): 
+ 
+    StackContext takes the function itself rather than its result:: 
+ 
+      with StackContext(my_context): 
+ 
+    The result of ``with StackContext() as cb:`` is a deactivation 
+    callback.  Run this callback when the StackContext is no longer 
+    needed to ensure that it is not propagated any further (note that 
+    deactivating a context does not affect any instances of that 
+    context that are currently pending).  This is an advanced feature 
+    and not necessary in most applications. 
+    """ 
+    def __init__(self, context_factory): 
+        self.context_factory = context_factory 
+        self.contexts = [] 
+        self.active = True 
+ 
+    def _deactivate(self): 
+        self.active = False 
+ 
+    # StackContext protocol 
+    def enter(self): 
+        context = self.context_factory() 
+        self.contexts.append(context) 
+        context.__enter__() 
+ 
+    def exit(self, type, value, traceback): 
+        context = self.contexts.pop() 
+        context.__exit__(type, value, traceback) 
+ 
+    # Note that some of this code is duplicated in ExceptionStackContext 
+    # below.  ExceptionStackContext is more common and doesn't need 
+    # the full generality of this class. 
+    def __enter__(self): 
+        self.old_contexts = _state.contexts 
+        self.new_contexts = (self.old_contexts[0] + (self,), self) 
+        _state.contexts = self.new_contexts 
+ 
+        try: 
+            self.enter() 
+        except: 
+            _state.contexts = self.old_contexts 
+            raise 
+ 
+        return self._deactivate 
+ 
+    def __exit__(self, type, value, traceback): 
+        try: 
+            self.exit(type, value, traceback) 
+        finally: 
+            final_contexts = _state.contexts 
+            _state.contexts = self.old_contexts 
+ 
+            # Generator coroutines and with-statements with non-local 
+            # effects interact badly.  Check here for signs of 
+            # the stack getting out of sync. 
+            # Note that this check comes after restoring _state.context 
+            # so that if it fails things are left in a (relatively) 
+            # consistent state. 
+            if final_contexts is not self.new_contexts: 
+                raise StackContextInconsistentError( 
+                    'stack_context inconsistency (may be caused by yield ' 
+                    'within a "with StackContext" block)') 
+ 
+            # Break up a reference to itself to allow for faster GC on CPython. 
+            self.new_contexts = None 
+ 
+ 
+class ExceptionStackContext(object): 
+    """Specialization of StackContext for exception handling. 
+ 
+    The supplied ``exception_handler`` function will be called in the 
+    event of an uncaught exception in this context.  The semantics are 
+    similar to a try/finally clause, and intended use cases are to log 
+    an error, close a socket, or similar cleanup actions.  The 
+    ``exc_info`` triple ``(type, value, traceback)`` will be passed to the 
+    exception_handler function. 
+ 
+    If the exception handler returns true, the exception will be 
+    consumed and will not be propagated to other exception handlers. 
+    """ 
+    def __init__(self, exception_handler): 
+        self.exception_handler = exception_handler 
+        self.active = True 
+ 
+    def _deactivate(self): 
+        self.active = False 
+ 
+    def exit(self, type, value, traceback): 
+        if type is not None: 
+            return self.exception_handler(type, value, traceback) 
+ 
+    def __enter__(self): 
+        self.old_contexts = _state.contexts 
+        self.new_contexts = (self.old_contexts[0], self) 
+        _state.contexts = self.new_contexts 
+ 
+        return self._deactivate 
+ 
+    def __exit__(self, type, value, traceback): 
+        try: 
+            if type is not None: 
+                return self.exception_handler(type, value, traceback) 
+        finally: 
+            final_contexts = _state.contexts 
+            _state.contexts = self.old_contexts 
+ 
+            if final_contexts is not self.new_contexts: 
+                raise StackContextInconsistentError( 
+                    'stack_context inconsistency (may be caused by yield ' 
+                    'within a "with StackContext" block)') 
+ 
+            # Break up a reference to itself to allow for faster GC on CPython. 
+            self.new_contexts = None 
+ 
+ 
+class NullContext(object): 
+    """Resets the `StackContext`. 
+ 
+    Useful when creating a shared resource on demand (e.g. an 
+    `.AsyncHTTPClient`) where the stack that caused the creating is 
+    not relevant to future operations. 
+    """ 
+    def __enter__(self): 
+        self.old_contexts = _state.contexts 
+        _state.contexts = (tuple(), None) 
+ 
+    def __exit__(self, type, value, traceback): 
+        _state.contexts = self.old_contexts 
+ 
+ 
+def _remove_deactivated(contexts): 
+    """Remove deactivated handlers from the chain""" 
+    # Clean ctx handlers 
+    stack_contexts = tuple([h for h in contexts[0] if h.active]) 
+ 
+    # Find new head 
+    head = contexts[1] 
+    while head is not None and not head.active: 
+        head = head.old_contexts[1] 
+ 
+    # Process chain 
+    ctx = head 
+    while ctx is not None: 
+        parent = ctx.old_contexts[1] 
+ 
+        while parent is not None: 
+            if parent.active: 
+                break 
+            ctx.old_contexts = parent.old_contexts 
+            parent = parent.old_contexts[1] 
+ 
+        ctx = parent 
+ 
+    return (stack_contexts, head) 
+ 
+ 
+def wrap(fn): 
+    """Returns a callable object that will restore the current `StackContext` 
+    when executed. 
+ 
+    Use this whenever saving a callback to be executed later in a 
+    different execution context (either in a different thread or 
+    asynchronously in the same thread). 
+    """ 
+    # Check if function is already wrapped 
+    if fn is None or hasattr(fn, '_wrapped'): 
+        return fn 
+ 
+    # Capture current stack head 
+    # TODO: Any other better way to store contexts and update them in wrapped function? 
+    cap_contexts = [_state.contexts] 
+ 
+    if not cap_contexts[0][0] and not cap_contexts[0][1]: 
+        # Fast path when there are no active contexts. 
+        def null_wrapper(*args, **kwargs): 
+            try: 
+                current_state = _state.contexts 
+                _state.contexts = cap_contexts[0] 
+                return fn(*args, **kwargs) 
+            finally: 
+                _state.contexts = current_state 
+        null_wrapper._wrapped = True 
+        return null_wrapper 
+ 
+    def wrapped(*args, **kwargs): 
+        ret = None 
+        try: 
+            # Capture old state 
+            current_state = _state.contexts 
+ 
+            # Remove deactivated items 
+            cap_contexts[0] = contexts = _remove_deactivated(cap_contexts[0]) 
+ 
+            # Force new state 
+            _state.contexts = contexts 
+ 
+            # Current exception 
+            exc = (None, None, None) 
+            top = None 
+ 
+            # Apply stack contexts 
+            last_ctx = 0 
+            stack = contexts[0] 
+ 
+            # Apply state 
+            for n in stack: 
+                try: 
+                    n.enter() 
+                    last_ctx += 1 
+                except: 
+                    # Exception happened. Record exception info and store top-most handler 
+                    exc = sys.exc_info() 
+                    top = n.old_contexts[1] 
+ 
+            # Execute callback if no exception happened while restoring state 
+            if top is None: 
+                try: 
+                    ret = fn(*args, **kwargs) 
+                except: 
+                    exc = sys.exc_info() 
+                    top = contexts[1] 
+ 
+            # If there was exception, try to handle it by going through the exception chain 
+            if top is not None: 
+                exc = _handle_exception(top, exc) 
+            else: 
+                # Otherwise take shorter path and run stack contexts in reverse order 
+                while last_ctx > 0: 
+                    last_ctx -= 1 
+                    c = stack[last_ctx] 
+ 
+                    try: 
+                        c.exit(*exc) 
+                    except: 
+                        exc = sys.exc_info() 
+                        top = c.old_contexts[1] 
+                        break 
+                else: 
+                    top = None 
+ 
+                # If if exception happened while unrolling, take longer exception handler path 
+                if top is not None: 
+                    exc = _handle_exception(top, exc) 
+ 
+            # If exception was not handled, raise it 
+            if exc != (None, None, None): 
+                raise_exc_info(exc) 
+        finally: 
+            _state.contexts = current_state 
+        return ret 
+ 
+    wrapped._wrapped = True 
+    return wrapped 
+ 
+ 
+def _handle_exception(tail, exc): 
+    while tail is not None: 
+        try: 
+            if tail.exit(*exc): 
+                exc = (None, None, None) 
+        except: 
+            exc = sys.exc_info() 
+ 
+        tail = tail.old_contexts[1] 
+ 
+    return exc 
+ 
+ 
+def run_with_stack_context(context, func): 
+    """Run a coroutine ``func`` in the given `StackContext`. 
+ 
+    It is not safe to have a ``yield`` statement within a ``with StackContext`` 
+    block, so it is difficult to use stack context with `.gen.coroutine`. 
+    This helper function runs the function in the correct context while 
+    keeping the ``yield`` and ``with`` statements syntactically separate. 
+ 
+    Example:: 
+ 
+        @gen.coroutine 
+        def incorrect(): 
+            with StackContext(ctx): 
+                # ERROR: this will raise StackContextInconsistentError 
+                yield other_coroutine() 
+ 
+        @gen.coroutine 
+        def correct(): 
+            yield run_with_stack_context(StackContext(ctx), other_coroutine) 
+ 
+    .. versionadded:: 3.1 
+    """ 
+    with context: 
+        return func() 
diff --git a/contrib/python/tornado/tornado-4/tornado/tcpclient.py b/contrib/python/tornado/tornado-4/tornado/tcpclient.py
index bb5e9f347e..bf928d5c6e 100644
--- a/contrib/python/tornado/tornado-4/tornado/tcpclient.py
+++ b/contrib/python/tornado/tornado-4/tornado/tcpclient.py
@@ -1,224 +1,224 @@
-#!/usr/bin/env python
-#
-# Copyright 2014 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""A non-blocking TCP connection factory.
-"""
-from __future__ import absolute_import, division, print_function
-
-import functools
-import socket
-
-from tornado.concurrent import Future
-from tornado.ioloop import IOLoop
-from tornado.iostream import IOStream
-from tornado import gen
-from tornado.netutil import Resolver
-from tornado.platform.auto import set_close_exec
-
-_INITIAL_CONNECT_TIMEOUT = 0.3
-
-
-class _Connector(object):
-    """A stateless implementation of the "Happy Eyeballs" algorithm.
-
-    "Happy Eyeballs" is documented in RFC6555 as the recommended practice
-    for when both IPv4 and IPv6 addresses are available.
-
-    In this implementation, we partition the addresses by family, and
-    make the first connection attempt to whichever address was
-    returned first by ``getaddrinfo``.  If that connection fails or
-    times out, we begin a connection in parallel to the first address
-    of the other family.  If there are additional failures we retry
-    with other addresses, keeping one connection attempt per family
-    in flight at a time.
-
-    http://tools.ietf.org/html/rfc6555
-
-    """
-    def __init__(self, addrinfo, io_loop, connect):
-        self.io_loop = io_loop
-        self.connect = connect
-
-        self.future = Future()
-        self.timeout = None
-        self.last_error = None
-        self.remaining = len(addrinfo)
-        self.primary_addrs, self.secondary_addrs = self.split(addrinfo)
-
-    @staticmethod
-    def split(addrinfo):
-        """Partition the ``addrinfo`` list by address family.
-
-        Returns two lists.  The first list contains the first entry from
-        ``addrinfo`` and all others with the same family, and the
-        second list contains all other addresses (normally one list will
-        be AF_INET and the other AF_INET6, although non-standard resolvers
-        may return additional families).
-        """
-        primary = []
-        secondary = []
-        primary_af = addrinfo[0][0]
-        for af, addr in addrinfo:
-            if af == primary_af:
-                primary.append((af, addr))
-            else:
-                secondary.append((af, addr))
-        return primary, secondary
-
-    def start(self, timeout=_INITIAL_CONNECT_TIMEOUT):
-        self.try_connect(iter(self.primary_addrs))
-        self.set_timout(timeout)
-        return self.future
-
-    def try_connect(self, addrs):
-        try:
-            af, addr = next(addrs)
-        except StopIteration:
-            # We've reached the end of our queue, but the other queue
-            # might still be working.  Send a final error on the future
-            # only when both queues are finished.
-            if self.remaining == 0 and not self.future.done():
-                self.future.set_exception(self.last_error or
-                                          IOError("connection failed"))
-            return
-        future = self.connect(af, addr)
-        future.add_done_callback(functools.partial(self.on_connect_done,
-                                                   addrs, af, addr))
-
-    def on_connect_done(self, addrs, af, addr, future):
-        self.remaining -= 1
-        try:
-            stream = future.result()
-        except Exception as e:
-            if self.future.done():
-                return
-            # Error: try again (but remember what happened so we have an
-            # error to raise in the end)
-            self.last_error = e
-            self.try_connect(addrs)
-            if self.timeout is not None:
-                # If the first attempt failed, don't wait for the
-                # timeout to try an address from the secondary queue.
-                self.io_loop.remove_timeout(self.timeout)
-                self.on_timeout()
-            return
-        self.clear_timeout()
-        if self.future.done():
-            # This is a late arrival; just drop it.
-            stream.close()
-        else:
-            self.future.set_result((af, addr, stream))
-
-    def set_timout(self, timeout):
-        self.timeout = self.io_loop.add_timeout(self.io_loop.time() + timeout,
-                                                self.on_timeout)
-
-    def on_timeout(self):
-        self.timeout = None
-        self.try_connect(iter(self.secondary_addrs))
-
-    def clear_timeout(self):
-        if self.timeout is not None:
-            self.io_loop.remove_timeout(self.timeout)
-
-
-class TCPClient(object):
-    """A non-blocking TCP connection factory.
-
-    .. versionchanged:: 4.1
-       The ``io_loop`` argument is deprecated.
-    """
-    def __init__(self, resolver=None, io_loop=None):
-        self.io_loop = io_loop or IOLoop.current()
-        if resolver is not None:
-            self.resolver = resolver
-            self._own_resolver = False
-        else:
-            self.resolver = Resolver(io_loop=io_loop)
-            self._own_resolver = True
-
-    def close(self):
-        if self._own_resolver:
-            self.resolver.close()
-
-    @gen.coroutine
-    def connect(self, host, port, af=socket.AF_UNSPEC, ssl_options=None,
-                max_buffer_size=None, source_ip=None, source_port=None):
-        """Connect to the given host and port.
-
-        Asynchronously returns an `.IOStream` (or `.SSLIOStream` if
-        ``ssl_options`` is not None).
-
-        Using the ``source_ip`` kwarg, one can specify the source
-        IP address to use when establishing the connection.
-        In case the user needs to resolve and
-        use a specific interface, it has to be handled outside
-        of Tornado as this depends very much on the platform.
-
-        Similarly, when the user requires a certain source port, it can
-        be specified using the ``source_port`` arg.
-
-        .. versionchanged:: 4.5
-           Added the ``source_ip`` and ``source_port`` arguments.
-        """
-        addrinfo = yield self.resolver.resolve(host, port, af)
-        connector = _Connector(
-            addrinfo, self.io_loop,
-            functools.partial(self._create_stream, max_buffer_size,
-                              source_ip=source_ip, source_port=source_port)
-        )
-        af, addr, stream = yield connector.start()
-        # TODO: For better performance we could cache the (af, addr)
-        # information here and re-use it on subsequent connections to
-        # the same host. (http://tools.ietf.org/html/rfc6555#section-4.2)
-        if ssl_options is not None:
-            stream = yield stream.start_tls(False, ssl_options=ssl_options,
-                                            server_hostname=host)
-        raise gen.Return(stream)
-
-    def _create_stream(self, max_buffer_size, af, addr, source_ip=None,
-                       source_port=None):
-        # Always connect in plaintext; we'll convert to ssl if necessary
-        # after one connection has completed.
-        source_port_bind = source_port if isinstance(source_port, int) else 0
-        source_ip_bind = source_ip
-        if source_port_bind and not source_ip:
-            # User required a specific port, but did not specify
-            # a certain source IP, will bind to the default loopback.
-            source_ip_bind = '::1' if af == socket.AF_INET6 else '127.0.0.1'
-            # Trying to use the same address family as the requested af socket:
-            # - 127.0.0.1 for IPv4
-            # - ::1 for IPv6
-        socket_obj = socket.socket(af)
-        set_close_exec(socket_obj.fileno())
-        if source_port_bind or source_ip_bind:
-            # If the user requires binding also to a specific IP/port.
-            try:
-                socket_obj.bind((source_ip_bind, source_port_bind))
-            except socket.error:
-                socket_obj.close()
-                # Fail loudly if unable to use the IP/port.
-                raise
-        try:
-            stream = IOStream(socket_obj,
-                              io_loop=self.io_loop,
-                              max_buffer_size=max_buffer_size)
-        except socket.error as e:
-            fu = Future()
-            fu.set_exception(e)
-            return fu
-        else:
-            return stream.connect(addr)
+#!/usr/bin/env python 
+# 
+# Copyright 2014 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""A non-blocking TCP connection factory. 
+""" 
+from __future__ import absolute_import, division, print_function 
+ 
+import functools 
+import socket 
+ 
+from tornado.concurrent import Future 
+from tornado.ioloop import IOLoop 
+from tornado.iostream import IOStream 
+from tornado import gen 
+from tornado.netutil import Resolver 
+from tornado.platform.auto import set_close_exec 
+ 
+_INITIAL_CONNECT_TIMEOUT = 0.3 
+ 
+ 
+class _Connector(object): 
+    """A stateless implementation of the "Happy Eyeballs" algorithm. 
+ 
+    "Happy Eyeballs" is documented in RFC6555 as the recommended practice 
+    for when both IPv4 and IPv6 addresses are available. 
+ 
+    In this implementation, we partition the addresses by family, and 
+    make the first connection attempt to whichever address was 
+    returned first by ``getaddrinfo``.  If that connection fails or 
+    times out, we begin a connection in parallel to the first address 
+    of the other family.  If there are additional failures we retry 
+    with other addresses, keeping one connection attempt per family 
+    in flight at a time. 
+ 
+    http://tools.ietf.org/html/rfc6555 
+ 
+    """ 
+    def __init__(self, addrinfo, io_loop, connect): 
+        self.io_loop = io_loop 
+        self.connect = connect 
+ 
+        self.future = Future() 
+        self.timeout = None 
+        self.last_error = None 
+        self.remaining = len(addrinfo) 
+        self.primary_addrs, self.secondary_addrs = self.split(addrinfo) 
+ 
+    @staticmethod 
+    def split(addrinfo): 
+        """Partition the ``addrinfo`` list by address family. 
+ 
+        Returns two lists.  The first list contains the first entry from 
+        ``addrinfo`` and all others with the same family, and the 
+        second list contains all other addresses (normally one list will 
+        be AF_INET and the other AF_INET6, although non-standard resolvers 
+        may return additional families). 
+        """ 
+        primary = [] 
+        secondary = [] 
+        primary_af = addrinfo[0][0] 
+        for af, addr in addrinfo: 
+            if af == primary_af: 
+                primary.append((af, addr)) 
+            else: 
+                secondary.append((af, addr)) 
+        return primary, secondary 
+ 
+    def start(self, timeout=_INITIAL_CONNECT_TIMEOUT): 
+        self.try_connect(iter(self.primary_addrs)) 
+        self.set_timout(timeout) 
+        return self.future 
+ 
+    def try_connect(self, addrs): 
+        try: 
+            af, addr = next(addrs) 
+        except StopIteration: 
+            # We've reached the end of our queue, but the other queue 
+            # might still be working.  Send a final error on the future 
+            # only when both queues are finished. 
+            if self.remaining == 0 and not self.future.done(): 
+                self.future.set_exception(self.last_error or 
+                                          IOError("connection failed")) 
+            return 
+        future = self.connect(af, addr) 
+        future.add_done_callback(functools.partial(self.on_connect_done, 
+                                                   addrs, af, addr)) 
+ 
+    def on_connect_done(self, addrs, af, addr, future): 
+        self.remaining -= 1 
+        try: 
+            stream = future.result() 
+        except Exception as e: 
+            if self.future.done(): 
+                return 
+            # Error: try again (but remember what happened so we have an 
+            # error to raise in the end) 
+            self.last_error = e 
+            self.try_connect(addrs) 
+            if self.timeout is not None: 
+                # If the first attempt failed, don't wait for the 
+                # timeout to try an address from the secondary queue. 
+                self.io_loop.remove_timeout(self.timeout) 
+                self.on_timeout() 
+            return 
+        self.clear_timeout() 
+        if self.future.done(): 
+            # This is a late arrival; just drop it. 
+            stream.close() 
+        else: 
+            self.future.set_result((af, addr, stream)) 
+ 
+    def set_timout(self, timeout): 
+        self.timeout = self.io_loop.add_timeout(self.io_loop.time() + timeout, 
+                                                self.on_timeout) 
+ 
+    def on_timeout(self): 
+        self.timeout = None 
+        self.try_connect(iter(self.secondary_addrs)) 
+ 
+    def clear_timeout(self): 
+        if self.timeout is not None: 
+            self.io_loop.remove_timeout(self.timeout) 
+ 
+ 
+class TCPClient(object): 
+    """A non-blocking TCP connection factory. 
+ 
+    .. versionchanged:: 4.1 
+       The ``io_loop`` argument is deprecated. 
+    """ 
+    def __init__(self, resolver=None, io_loop=None): 
+        self.io_loop = io_loop or IOLoop.current() 
+        if resolver is not None: 
+            self.resolver = resolver 
+            self._own_resolver = False 
+        else: 
+            self.resolver = Resolver(io_loop=io_loop) 
+            self._own_resolver = True 
+ 
+    def close(self): 
+        if self._own_resolver: 
+            self.resolver.close() 
+ 
+    @gen.coroutine 
+    def connect(self, host, port, af=socket.AF_UNSPEC, ssl_options=None, 
+                max_buffer_size=None, source_ip=None, source_port=None): 
+        """Connect to the given host and port. 
+ 
+        Asynchronously returns an `.IOStream` (or `.SSLIOStream` if 
+        ``ssl_options`` is not None). 
+ 
+        Using the ``source_ip`` kwarg, one can specify the source 
+        IP address to use when establishing the connection. 
+        In case the user needs to resolve and 
+        use a specific interface, it has to be handled outside 
+        of Tornado as this depends very much on the platform. 
+ 
+        Similarly, when the user requires a certain source port, it can 
+        be specified using the ``source_port`` arg. 
+ 
+        .. versionchanged:: 4.5 
+           Added the ``source_ip`` and ``source_port`` arguments. 
+        """ 
+        addrinfo = yield self.resolver.resolve(host, port, af) 
+        connector = _Connector( 
+            addrinfo, self.io_loop, 
+            functools.partial(self._create_stream, max_buffer_size, 
+                              source_ip=source_ip, source_port=source_port) 
+        ) 
+        af, addr, stream = yield connector.start() 
+        # TODO: For better performance we could cache the (af, addr) 
+        # information here and re-use it on subsequent connections to 
+        # the same host. (http://tools.ietf.org/html/rfc6555#section-4.2) 
+        if ssl_options is not None: 
+            stream = yield stream.start_tls(False, ssl_options=ssl_options, 
+                                            server_hostname=host) 
+        raise gen.Return(stream) 
+ 
+    def _create_stream(self, max_buffer_size, af, addr, source_ip=None, 
+                       source_port=None): 
+        # Always connect in plaintext; we'll convert to ssl if necessary 
+        # after one connection has completed. 
+        source_port_bind = source_port if isinstance(source_port, int) else 0 
+        source_ip_bind = source_ip 
+        if source_port_bind and not source_ip: 
+            # User required a specific port, but did not specify 
+            # a certain source IP, will bind to the default loopback. 
+            source_ip_bind = '::1' if af == socket.AF_INET6 else '127.0.0.1' 
+            # Trying to use the same address family as the requested af socket: 
+            # - 127.0.0.1 for IPv4 
+            # - ::1 for IPv6 
+        socket_obj = socket.socket(af) 
+        set_close_exec(socket_obj.fileno()) 
+        if source_port_bind or source_ip_bind: 
+            # If the user requires binding also to a specific IP/port. 
+            try: 
+                socket_obj.bind((source_ip_bind, source_port_bind)) 
+            except socket.error: 
+                socket_obj.close() 
+                # Fail loudly if unable to use the IP/port. 
+                raise 
+        try: 
+            stream = IOStream(socket_obj, 
+                              io_loop=self.io_loop, 
+                              max_buffer_size=max_buffer_size) 
+        except socket.error as e: 
+            fu = Future() 
+            fu.set_exception(e) 
+            return fu 
+        else: 
+            return stream.connect(addr) 
diff --git a/contrib/python/tornado/tornado-4/tornado/tcpserver.py b/contrib/python/tornado/tornado-4/tornado/tcpserver.py
index f47ec89a42..9ea1784bda 100644
--- a/contrib/python/tornado/tornado-4/tornado/tcpserver.py
+++ b/contrib/python/tornado/tornado-4/tornado/tcpserver.py
@@ -1,300 +1,300 @@
-#!/usr/bin/env python
-#
-# Copyright 2011 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""A non-blocking, single-threaded TCP server."""
-from __future__ import absolute_import, division, print_function
-
-import errno
-import os
-import socket
-
-from tornado import gen
-from tornado.log import app_log
-from tornado.ioloop import IOLoop
-from tornado.iostream import IOStream, SSLIOStream
-from tornado.netutil import bind_sockets, add_accept_handler, ssl_wrap_socket
-from tornado import process
-from tornado.util import errno_from_exception
-
-try:
-    import ssl
-except ImportError:
-    # ssl is not available on Google App Engine.
-    ssl = None
-
-
-class TCPServer(object):
-    r"""A non-blocking, single-threaded TCP server.
-
-    To use `TCPServer`, define a subclass which overrides the `handle_stream`
-    method. For example, a simple echo server could be defined like this::
-
-      from tornado.tcpserver import TCPServer
-      from tornado.iostream import StreamClosedError
-      from tornado import gen
-
-      class EchoServer(TCPServer):
-          @gen.coroutine
-          def handle_stream(self, stream, address):
-              while True:
-                  try:
-                      data = yield stream.read_until(b"\n")
-                      yield stream.write(data)
-                  except StreamClosedError:
-                      break
-
-    To make this server serve SSL traffic, send the ``ssl_options`` keyword
-    argument with an `ssl.SSLContext` object. For compatibility with older
-    versions of Python ``ssl_options`` may also be a dictionary of keyword
-    arguments for the `ssl.wrap_socket` method.::
-
-       ssl_ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
-       ssl_ctx.load_cert_chain(os.path.join(data_dir, "mydomain.crt"),
-                               os.path.join(data_dir, "mydomain.key"))
-       TCPServer(ssl_options=ssl_ctx)
-
-    `TCPServer` initialization follows one of three patterns:
-
-    1. `listen`: simple single-process::
-
-            server = TCPServer()
-            server.listen(8888)
-            IOLoop.current().start()
-
-    2. `bind`/`start`: simple multi-process::
-
-            server = TCPServer()
-            server.bind(8888)
-            server.start(0)  # Forks multiple sub-processes
-            IOLoop.current().start()
-
-       When using this interface, an `.IOLoop` must *not* be passed
-       to the `TCPServer` constructor.  `start` will always start
-       the server on the default singleton `.IOLoop`.
-
-    3. `add_sockets`: advanced multi-process::
-
-            sockets = bind_sockets(8888)
-            tornado.process.fork_processes(0)
-            server = TCPServer()
-            server.add_sockets(sockets)
-            IOLoop.current().start()
-
-       The `add_sockets` interface is more complicated, but it can be
-       used with `tornado.process.fork_processes` to give you more
-       flexibility in when the fork happens.  `add_sockets` can
-       also be used in single-process servers if you want to create
-       your listening sockets in some way other than
-       `~tornado.netutil.bind_sockets`.
-
-    .. versionadded:: 3.1
-       The ``max_buffer_size`` argument.
-    """
-    def __init__(self, io_loop=None, ssl_options=None, max_buffer_size=None,
-                 read_chunk_size=None):
-        self.io_loop = io_loop
-        self.ssl_options = ssl_options
-        self._sockets = {}  # fd -> socket object
-        self._pending_sockets = []
-        self._started = False
-        self._stopped = False
-        self.max_buffer_size = max_buffer_size
-        self.read_chunk_size = read_chunk_size
-
-        # Verify the SSL options. Otherwise we don't get errors until clients
-        # connect. This doesn't verify that the keys are legitimate, but
-        # the SSL module doesn't do that until there is a connected socket
-        # which seems like too much work
-        if self.ssl_options is not None and isinstance(self.ssl_options, dict):
-            # Only certfile is required: it can contain both keys
-            if 'certfile' not in self.ssl_options:
-                raise KeyError('missing key "certfile" in ssl_options')
-
-            if not os.path.exists(self.ssl_options['certfile']):
-                raise ValueError('certfile "%s" does not exist' %
-                                 self.ssl_options['certfile'])
-            if ('keyfile' in self.ssl_options and
-                    not os.path.exists(self.ssl_options['keyfile'])):
-                raise ValueError('keyfile "%s" does not exist' %
-                                 self.ssl_options['keyfile'])
-
-    def listen(self, port, address=""):
-        """Starts accepting connections on the given port.
-
-        This method may be called more than once to listen on multiple ports.
-        `listen` takes effect immediately; it is not necessary to call
-        `TCPServer.start` afterwards.  It is, however, necessary to start
-        the `.IOLoop`.
-        """
-        sockets = bind_sockets(port, address=address)
-        self.add_sockets(sockets)
-
-    def add_sockets(self, sockets):
-        """Makes this server start accepting connections on the given sockets.
-
-        The ``sockets`` parameter is a list of socket objects such as
-        those returned by `~tornado.netutil.bind_sockets`.
-        `add_sockets` is typically used in combination with that
-        method and `tornado.process.fork_processes` to provide greater
-        control over the initialization of a multi-process server.
-        """
-        if self.io_loop is None:
-            self.io_loop = IOLoop.current()
-
-        for sock in sockets:
-            self._sockets[sock.fileno()] = sock
-            add_accept_handler(sock, self._handle_connection,
-                               io_loop=self.io_loop)
-
-    def add_socket(self, socket):
-        """Singular version of `add_sockets`.  Takes a single socket object."""
-        self.add_sockets([socket])
-
-    def bind(self, port, address=None, family=socket.AF_UNSPEC, backlog=128,
-             reuse_port=False):
-        """Binds this server to the given port on the given address.
-
-        To start the server, call `start`. If you want to run this server
-        in a single process, you can call `listen` as a shortcut to the
-        sequence of `bind` and `start` calls.
-
-        Address may be either an IP address or hostname.  If it's a hostname,
-        the server will listen on all IP addresses associated with the
-        name.  Address may be an empty string or None to listen on all
-        available interfaces.  Family may be set to either `socket.AF_INET`
-        or `socket.AF_INET6` to restrict to IPv4 or IPv6 addresses, otherwise
-        both will be used if available.
-
-        The ``backlog`` argument has the same meaning as for
-        `socket.listen <socket.socket.listen>`. The ``reuse_port`` argument
-        has the same meaning as for `.bind_sockets`.
-
-        This method may be called multiple times prior to `start` to listen
-        on multiple ports or interfaces.
-
-        .. versionchanged:: 4.4
-           Added the ``reuse_port`` argument.
-        """
-        sockets = bind_sockets(port, address=address, family=family,
-                               backlog=backlog, reuse_port=reuse_port)
-        if self._started:
-            self.add_sockets(sockets)
-        else:
-            self._pending_sockets.extend(sockets)
-
-    def start(self, num_processes=1):
-        """Starts this server in the `.IOLoop`.
-
-        By default, we run the server in this process and do not fork any
-        additional child process.
-
-        If num_processes is ``None`` or <= 0, we detect the number of cores
-        available on this machine and fork that number of child
-        processes. If num_processes is given and > 1, we fork that
-        specific number of sub-processes.
-
-        Since we use processes and not threads, there is no shared memory
-        between any server code.
-
-        Note that multiple processes are not compatible with the autoreload
-        module (or the ``autoreload=True`` option to `tornado.web.Application`
-        which defaults to True when ``debug=True``).
-        When using multiple processes, no IOLoops can be created or
-        referenced until after the call to ``TCPServer.start(n)``.
-        """
-        assert not self._started
-        self._started = True
-        if num_processes != 1:
-            process.fork_processes(num_processes)
-        sockets = self._pending_sockets
-        self._pending_sockets = []
-        self.add_sockets(sockets)
-
-    def stop(self):
-        """Stops listening for new connections.
-
-        Requests currently in progress may still continue after the
-        server is stopped.
-        """
-        if self._stopped:
-            return
-        self._stopped = True
-        for fd, sock in self._sockets.items():
-            assert sock.fileno() == fd
-            self.io_loop.remove_handler(fd)
-            sock.close()
-
-    def handle_stream(self, stream, address):
-        """Override to handle a new `.IOStream` from an incoming connection.
-
-        This method may be a coroutine; if so any exceptions it raises
-        asynchronously will be logged. Accepting of incoming connections
-        will not be blocked by this coroutine.
-
-        If this `TCPServer` is configured for SSL, ``handle_stream``
-        may be called before the SSL handshake has completed. Use
-        `.SSLIOStream.wait_for_handshake` if you need to verify the client's
-        certificate or use NPN/ALPN.
-
-        .. versionchanged:: 4.2
-           Added the option for this method to be a coroutine.
-        """
-        raise NotImplementedError()
-
-    def _handle_connection(self, connection, address):
-        if self.ssl_options is not None:
-            assert ssl, "Python 2.6+ and OpenSSL required for SSL"
-            try:
-                connection = ssl_wrap_socket(connection,
-                                             self.ssl_options,
-                                             server_side=True,
-                                             do_handshake_on_connect=False)
-            except ssl.SSLError as err:
-                if err.args[0] == ssl.SSL_ERROR_EOF:
-                    return connection.close()
-                else:
-                    raise
-            except socket.error as err:
-                # If the connection is closed immediately after it is created
-                # (as in a port scan), we can get one of several errors.
-                # wrap_socket makes an internal call to getpeername,
-                # which may return either EINVAL (Mac OS X) or ENOTCONN
-                # (Linux).  If it returns ENOTCONN, this error is
-                # silently swallowed by the ssl module, so we need to
-                # catch another error later on (AttributeError in
-                # SSLIOStream._do_ssl_handshake).
-                # To test this behavior, try nmap with the -sT flag.
-                # https://github.com/tornadoweb/tornado/pull/750
-                if errno_from_exception(err) in (errno.ECONNABORTED, errno.EINVAL):
-                    return connection.close()
-                else:
-                    raise
-        try:
-            if self.ssl_options is not None:
-                stream = SSLIOStream(connection, io_loop=self.io_loop,
-                                     max_buffer_size=self.max_buffer_size,
-                                     read_chunk_size=self.read_chunk_size)
-            else:
-                stream = IOStream(connection, io_loop=self.io_loop,
-                                  max_buffer_size=self.max_buffer_size,
-                                  read_chunk_size=self.read_chunk_size)
-
-            future = self.handle_stream(stream, address)
-            if future is not None:
-                self.io_loop.add_future(gen.convert_yielded(future),
-                                        lambda f: f.result())
-        except Exception:
-            app_log.error("Error in connection callback", exc_info=True)
+#!/usr/bin/env python 
+# 
+# Copyright 2011 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""A non-blocking, single-threaded TCP server.""" 
+from __future__ import absolute_import, division, print_function 
+ 
+import errno 
+import os 
+import socket 
+ 
+from tornado import gen 
+from tornado.log import app_log 
+from tornado.ioloop import IOLoop 
+from tornado.iostream import IOStream, SSLIOStream 
+from tornado.netutil import bind_sockets, add_accept_handler, ssl_wrap_socket 
+from tornado import process 
+from tornado.util import errno_from_exception 
+ 
+try: 
+    import ssl 
+except ImportError: 
+    # ssl is not available on Google App Engine. 
+    ssl = None 
+ 
+ 
+class TCPServer(object): 
+    r"""A non-blocking, single-threaded TCP server. 
+ 
+    To use `TCPServer`, define a subclass which overrides the `handle_stream` 
+    method. For example, a simple echo server could be defined like this:: 
+ 
+      from tornado.tcpserver import TCPServer 
+      from tornado.iostream import StreamClosedError 
+      from tornado import gen 
+ 
+      class EchoServer(TCPServer): 
+          @gen.coroutine 
+          def handle_stream(self, stream, address): 
+              while True: 
+                  try: 
+                      data = yield stream.read_until(b"\n") 
+                      yield stream.write(data) 
+                  except StreamClosedError: 
+                      break 
+ 
+    To make this server serve SSL traffic, send the ``ssl_options`` keyword 
+    argument with an `ssl.SSLContext` object. For compatibility with older 
+    versions of Python ``ssl_options`` may also be a dictionary of keyword 
+    arguments for the `ssl.wrap_socket` method.:: 
+ 
+       ssl_ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH) 
+       ssl_ctx.load_cert_chain(os.path.join(data_dir, "mydomain.crt"), 
+                               os.path.join(data_dir, "mydomain.key")) 
+       TCPServer(ssl_options=ssl_ctx) 
+ 
+    `TCPServer` initialization follows one of three patterns: 
+ 
+    1. `listen`: simple single-process:: 
+ 
+            server = TCPServer() 
+            server.listen(8888) 
+            IOLoop.current().start() 
+ 
+    2. `bind`/`start`: simple multi-process:: 
+ 
+            server = TCPServer() 
+            server.bind(8888) 
+            server.start(0)  # Forks multiple sub-processes 
+            IOLoop.current().start() 
+ 
+       When using this interface, an `.IOLoop` must *not* be passed 
+       to the `TCPServer` constructor.  `start` will always start 
+       the server on the default singleton `.IOLoop`. 
+ 
+    3. `add_sockets`: advanced multi-process:: 
+ 
+            sockets = bind_sockets(8888) 
+            tornado.process.fork_processes(0) 
+            server = TCPServer() 
+            server.add_sockets(sockets) 
+            IOLoop.current().start() 
+ 
+       The `add_sockets` interface is more complicated, but it can be 
+       used with `tornado.process.fork_processes` to give you more 
+       flexibility in when the fork happens.  `add_sockets` can 
+       also be used in single-process servers if you want to create 
+       your listening sockets in some way other than 
+       `~tornado.netutil.bind_sockets`. 
+ 
+    .. versionadded:: 3.1 
+       The ``max_buffer_size`` argument. 
+    """ 
+    def __init__(self, io_loop=None, ssl_options=None, max_buffer_size=None, 
+                 read_chunk_size=None): 
+        self.io_loop = io_loop 
+        self.ssl_options = ssl_options 
+        self._sockets = {}  # fd -> socket object 
+        self._pending_sockets = [] 
+        self._started = False 
+        self._stopped = False 
+        self.max_buffer_size = max_buffer_size 
+        self.read_chunk_size = read_chunk_size 
+ 
+        # Verify the SSL options. Otherwise we don't get errors until clients 
+        # connect. This doesn't verify that the keys are legitimate, but 
+        # the SSL module doesn't do that until there is a connected socket 
+        # which seems like too much work 
+        if self.ssl_options is not None and isinstance(self.ssl_options, dict): 
+            # Only certfile is required: it can contain both keys 
+            if 'certfile' not in self.ssl_options: 
+                raise KeyError('missing key "certfile" in ssl_options') 
+ 
+            if not os.path.exists(self.ssl_options['certfile']): 
+                raise ValueError('certfile "%s" does not exist' % 
+                                 self.ssl_options['certfile']) 
+            if ('keyfile' in self.ssl_options and 
+                    not os.path.exists(self.ssl_options['keyfile'])): 
+                raise ValueError('keyfile "%s" does not exist' % 
+                                 self.ssl_options['keyfile']) 
+ 
+    def listen(self, port, address=""): 
+        """Starts accepting connections on the given port. 
+ 
+        This method may be called more than once to listen on multiple ports. 
+        `listen` takes effect immediately; it is not necessary to call 
+        `TCPServer.start` afterwards.  It is, however, necessary to start 
+        the `.IOLoop`. 
+        """ 
+        sockets = bind_sockets(port, address=address) 
+        self.add_sockets(sockets) 
+ 
+    def add_sockets(self, sockets): 
+        """Makes this server start accepting connections on the given sockets. 
+ 
+        The ``sockets`` parameter is a list of socket objects such as 
+        those returned by `~tornado.netutil.bind_sockets`. 
+        `add_sockets` is typically used in combination with that 
+        method and `tornado.process.fork_processes` to provide greater 
+        control over the initialization of a multi-process server. 
+        """ 
+        if self.io_loop is None: 
+            self.io_loop = IOLoop.current() 
+ 
+        for sock in sockets: 
+            self._sockets[sock.fileno()] = sock 
+            add_accept_handler(sock, self._handle_connection, 
+                               io_loop=self.io_loop) 
+ 
+    def add_socket(self, socket): 
+        """Singular version of `add_sockets`.  Takes a single socket object.""" 
+        self.add_sockets([socket]) 
+ 
+    def bind(self, port, address=None, family=socket.AF_UNSPEC, backlog=128, 
+             reuse_port=False): 
+        """Binds this server to the given port on the given address. 
+ 
+        To start the server, call `start`. If you want to run this server 
+        in a single process, you can call `listen` as a shortcut to the 
+        sequence of `bind` and `start` calls. 
+ 
+        Address may be either an IP address or hostname.  If it's a hostname, 
+        the server will listen on all IP addresses associated with the 
+        name.  Address may be an empty string or None to listen on all 
+        available interfaces.  Family may be set to either `socket.AF_INET` 
+        or `socket.AF_INET6` to restrict to IPv4 or IPv6 addresses, otherwise 
+        both will be used if available. 
+ 
+        The ``backlog`` argument has the same meaning as for 
+        `socket.listen <socket.socket.listen>`. The ``reuse_port`` argument 
+        has the same meaning as for `.bind_sockets`. 
+ 
+        This method may be called multiple times prior to `start` to listen 
+        on multiple ports or interfaces. 
+ 
+        .. versionchanged:: 4.4 
+           Added the ``reuse_port`` argument. 
+        """ 
+        sockets = bind_sockets(port, address=address, family=family, 
+                               backlog=backlog, reuse_port=reuse_port) 
+        if self._started: 
+            self.add_sockets(sockets) 
+        else: 
+            self._pending_sockets.extend(sockets) 
+ 
+    def start(self, num_processes=1): 
+        """Starts this server in the `.IOLoop`. 
+ 
+        By default, we run the server in this process and do not fork any 
+        additional child process. 
+ 
+        If num_processes is ``None`` or <= 0, we detect the number of cores 
+        available on this machine and fork that number of child 
+        processes. If num_processes is given and > 1, we fork that 
+        specific number of sub-processes. 
+ 
+        Since we use processes and not threads, there is no shared memory 
+        between any server code. 
+ 
+        Note that multiple processes are not compatible with the autoreload 
+        module (or the ``autoreload=True`` option to `tornado.web.Application` 
+        which defaults to True when ``debug=True``). 
+        When using multiple processes, no IOLoops can be created or 
+        referenced until after the call to ``TCPServer.start(n)``. 
+        """ 
+        assert not self._started 
+        self._started = True 
+        if num_processes != 1: 
+            process.fork_processes(num_processes) 
+        sockets = self._pending_sockets 
+        self._pending_sockets = [] 
+        self.add_sockets(sockets) 
+ 
+    def stop(self): 
+        """Stops listening for new connections. 
+ 
+        Requests currently in progress may still continue after the 
+        server is stopped. 
+        """ 
+        if self._stopped: 
+            return 
+        self._stopped = True 
+        for fd, sock in self._sockets.items(): 
+            assert sock.fileno() == fd 
+            self.io_loop.remove_handler(fd) 
+            sock.close() 
+ 
+    def handle_stream(self, stream, address): 
+        """Override to handle a new `.IOStream` from an incoming connection. 
+ 
+        This method may be a coroutine; if so any exceptions it raises 
+        asynchronously will be logged. Accepting of incoming connections 
+        will not be blocked by this coroutine. 
+ 
+        If this `TCPServer` is configured for SSL, ``handle_stream`` 
+        may be called before the SSL handshake has completed. Use 
+        `.SSLIOStream.wait_for_handshake` if you need to verify the client's 
+        certificate or use NPN/ALPN. 
+ 
+        .. versionchanged:: 4.2 
+           Added the option for this method to be a coroutine. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def _handle_connection(self, connection, address): 
+        if self.ssl_options is not None: 
+            assert ssl, "Python 2.6+ and OpenSSL required for SSL" 
+            try: 
+                connection = ssl_wrap_socket(connection, 
+                                             self.ssl_options, 
+                                             server_side=True, 
+                                             do_handshake_on_connect=False) 
+            except ssl.SSLError as err: 
+                if err.args[0] == ssl.SSL_ERROR_EOF: 
+                    return connection.close() 
+                else: 
+                    raise 
+            except socket.error as err: 
+                # If the connection is closed immediately after it is created 
+                # (as in a port scan), we can get one of several errors. 
+                # wrap_socket makes an internal call to getpeername, 
+                # which may return either EINVAL (Mac OS X) or ENOTCONN 
+                # (Linux).  If it returns ENOTCONN, this error is 
+                # silently swallowed by the ssl module, so we need to 
+                # catch another error later on (AttributeError in 
+                # SSLIOStream._do_ssl_handshake). 
+                # To test this behavior, try nmap with the -sT flag. 
+                # https://github.com/tornadoweb/tornado/pull/750 
+                if errno_from_exception(err) in (errno.ECONNABORTED, errno.EINVAL): 
+                    return connection.close() 
+                else: 
+                    raise 
+        try: 
+            if self.ssl_options is not None: 
+                stream = SSLIOStream(connection, io_loop=self.io_loop, 
+                                     max_buffer_size=self.max_buffer_size, 
+                                     read_chunk_size=self.read_chunk_size) 
+            else: 
+                stream = IOStream(connection, io_loop=self.io_loop, 
+                                  max_buffer_size=self.max_buffer_size, 
+                                  read_chunk_size=self.read_chunk_size) 
+ 
+            future = self.handle_stream(stream, address) 
+            if future is not None: 
+                self.io_loop.add_future(gen.convert_yielded(future), 
+                                        lambda f: f.result()) 
+        except Exception: 
+            app_log.error("Error in connection callback", exc_info=True) 
diff --git a/contrib/python/tornado/tornado-4/tornado/template.py b/contrib/python/tornado/tornado-4/tornado/template.py
index 3b2fa3feef..10c14d53c9 100644
--- a/contrib/python/tornado/tornado-4/tornado/template.py
+++ b/contrib/python/tornado/tornado-4/tornado/template.py
@@ -1,978 +1,978 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""A simple template system that compiles templates to Python code.
-
-Basic usage looks like::
-
-    t = template.Template("<html>{{ myvalue }}</html>")
-    print(t.generate(myvalue="XXX"))
-
-`Loader` is a class that loads templates from a root directory and caches
-the compiled templates::
-
-    loader = template.Loader("/home/btaylor")
-    print(loader.load("test.html").generate(myvalue="XXX"))
-
-We compile all templates to raw Python. Error-reporting is currently... uh,
-interesting. Syntax for the templates::
-
-    ### base.html
-    <html>
-      <head>
-        <title>{% block title %}Default title{% end %}</title>
-      </head>
-      <body>
-        <ul>
-          {% for student in students %}
-            {% block student %}
-              <li>{{ escape(student.name) }}</li>
-            {% end %}
-          {% end %}
-        </ul>
-      </body>
-    </html>
-
-    ### bold.html
-    {% extends "base.html" %}
-
-    {% block title %}A bolder title{% end %}
-
-    {% block student %}
-      <li><span style="bold">{{ escape(student.name) }}</span></li>
-    {% end %}
-
-Unlike most other template systems, we do not put any restrictions on the
-expressions you can include in your statements. ``if`` and ``for`` blocks get
-translated exactly into Python, so you can do complex expressions like::
-
-   {% for student in [p for p in people if p.student and p.age > 23] %}
-     <li>{{ escape(student.name) }}</li>
-   {% end %}
-
-Translating directly to Python means you can apply functions to expressions
-easily, like the ``escape()`` function in the examples above. You can pass
-functions in to your template just like any other variable
-(In a `.RequestHandler`, override `.RequestHandler.get_template_namespace`)::
-
-   ### Python code
-   def add(x, y):
-      return x + y
-   template.execute(add=add)
-
-   ### The template
-   {{ add(1, 2) }}
-
-We provide the functions `escape() <.xhtml_escape>`, `.url_escape()`,
-`.json_encode()`, and `.squeeze()` to all templates by default.
-
-Typical applications do not create `Template` or `Loader` instances by
-hand, but instead use the `~.RequestHandler.render` and
-`~.RequestHandler.render_string` methods of
-`tornado.web.RequestHandler`, which load templates automatically based
-on the ``template_path`` `.Application` setting.
-
-Variable names beginning with ``_tt_`` are reserved by the template
-system and should not be used by application code.
-
-Syntax Reference
-----------------
-
-Template expressions are surrounded by double curly braces: ``{{ ... }}``.
-The contents may be any python expression, which will be escaped according
-to the current autoescape setting and inserted into the output.  Other
-template directives use ``{% %}``.
-
-To comment out a section so that it is omitted from the output, surround it
-with ``{# ... #}``.
-
-These tags may be escaped as ``{{!``, ``{%!``, and ``{#!``
-if you need to include a literal ``{{``, ``{%``, or ``{#`` in the output.
-
-
-``{% apply *function* %}...{% end %}``
-    Applies a function to the output of all template code between ``apply``
-    and ``end``::
-
-        {% apply linkify %}{{name}} said: {{message}}{% end %}
-
-    Note that as an implementation detail apply blocks are implemented
-    as nested functions and thus may interact strangely with variables
-    set via ``{% set %}``, or the use of ``{% break %}`` or ``{% continue %}``
-    within loops.
-
-``{% autoescape *function* %}``
-    Sets the autoescape mode for the current file.  This does not affect
-    other files, even those referenced by ``{% include %}``.  Note that
-    autoescaping can also be configured globally, at the `.Application`
-    or `Loader`.::
-
-        {% autoescape xhtml_escape %}
-        {% autoescape None %}
-
-``{% block *name* %}...{% end %}``
-    Indicates a named, replaceable block for use with ``{% extends %}``.
-    Blocks in the parent template will be replaced with the contents of
-    the same-named block in a child template.::
-
-        <!-- base.html -->
-        <title>{% block title %}Default title{% end %}</title>
-
-        <!-- mypage.html -->
-        {% extends "base.html" %}
-        {% block title %}My page title{% end %}
-
-``{% comment ... %}``
-    A comment which will be removed from the template output.  Note that
-    there is no ``{% end %}`` tag; the comment goes from the word ``comment``
-    to the closing ``%}`` tag.
-
-``{% extends *filename* %}``
-    Inherit from another template.  Templates that use ``extends`` should
-    contain one or more ``block`` tags to replace content from the parent
-    template.  Anything in the child template not contained in a ``block``
-    tag will be ignored.  For an example, see the ``{% block %}`` tag.
-
-``{% for *var* in *expr* %}...{% end %}``
-    Same as the python ``for`` statement.  ``{% break %}`` and
-    ``{% continue %}`` may be used inside the loop.
-
-``{% from *x* import *y* %}``
-    Same as the python ``import`` statement.
-
-``{% if *condition* %}...{% elif *condition* %}...{% else %}...{% end %}``
-    Conditional statement - outputs the first section whose condition is
-    true.  (The ``elif`` and ``else`` sections are optional)
-
-``{% import *module* %}``
-    Same as the python ``import`` statement.
-
-``{% include *filename* %}``
-    Includes another template file.  The included file can see all the local
-    variables as if it were copied directly to the point of the ``include``
-    directive (the ``{% autoescape %}`` directive is an exception).
-    Alternately, ``{% module Template(filename, **kwargs) %}`` may be used
-    to include another template with an isolated namespace.
-
-``{% module *expr* %}``
-    Renders a `~tornado.web.UIModule`.  The output of the ``UIModule`` is
-    not escaped::
-
-        {% module Template("foo.html", arg=42) %}
-
-    ``UIModules`` are a feature of the `tornado.web.RequestHandler`
-    class (and specifically its ``render`` method) and will not work
-    when the template system is used on its own in other contexts.
-
-``{% raw *expr* %}``
-    Outputs the result of the given expression without autoescaping.
-
-``{% set *x* = *y* %}``
-    Sets a local variable.
-
-``{% try %}...{% except %}...{% else %}...{% finally %}...{% end %}``
-    Same as the python ``try`` statement.
-
-``{% while *condition* %}... {% end %}``
-    Same as the python ``while`` statement.  ``{% break %}`` and
-    ``{% continue %}`` may be used inside the loop.
-
-``{% whitespace *mode* %}``
-    Sets the whitespace mode for the remainder of the current file
-    (or until the next ``{% whitespace %}`` directive). See
-    `filter_whitespace` for available options. New in Tornado 4.3.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import datetime
-import linecache
-import os.path
-import posixpath
-import re
-import threading
-
-from tornado import escape
-from tornado.log import app_log
-from tornado.util import ObjectDict, exec_in, unicode_type, PY3
-
-if PY3:
-    from io import StringIO
-else:
-    from cStringIO import StringIO
-
-_DEFAULT_AUTOESCAPE = "xhtml_escape"
-_UNSET = object()
-
-
-def filter_whitespace(mode, text):
-    """Transform whitespace in ``text`` according to ``mode``.
-
-    Available modes are:
-
-    * ``all``: Return all whitespace unmodified.
-    * ``single``: Collapse consecutive whitespace with a single whitespace
-      character, preserving newlines.
-    * ``oneline``: Collapse all runs of whitespace into a single space
-      character, removing all newlines in the process.
-
-    .. versionadded:: 4.3
-    """
-    if mode == 'all':
-        return text
-    elif mode == 'single':
-        text = re.sub(r"([\t ]+)", " ", text)
-        text = re.sub(r"(\s*\n\s*)", "\n", text)
-        return text
-    elif mode == 'oneline':
-        return re.sub(r"(\s+)", " ", text)
-    else:
-        raise Exception("invalid whitespace mode %s" % mode)
-
-
-class Template(object):
-    """A compiled template.
-
-    We compile into Python from the given template_string. You can generate
-    the template from variables with generate().
-    """
-    # note that the constructor's signature is not extracted with
-    # autodoc because _UNSET looks like garbage.  When changing
-    # this signature update website/sphinx/template.rst too.
-    def __init__(self, template_string, name="<string>", loader=None,
-                 compress_whitespace=_UNSET, autoescape=_UNSET,
-                 whitespace=None):
-        """Construct a Template.
-
-        :arg str template_string: the contents of the template file.
-        :arg str name: the filename from which the template was loaded
-            (used for error message).
-        :arg tornado.template.BaseLoader loader: the `~tornado.template.BaseLoader` responsible for this template,
-            used to resolve ``{% include %}`` and ``{% extend %}``
-            directives.
-        :arg bool compress_whitespace: Deprecated since Tornado 4.3.
-            Equivalent to ``whitespace="single"`` if true and
-            ``whitespace="all"`` if false.
-        :arg str autoescape: The name of a function in the template
-            namespace, or ``None`` to disable escaping by default.
-        :arg str whitespace: A string specifying treatment of whitespace;
-            see `filter_whitespace` for options.
-
-        .. versionchanged:: 4.3
-           Added ``whitespace`` parameter; deprecated ``compress_whitespace``.
-        """
-        self.name = escape.native_str(name)
-
-        if compress_whitespace is not _UNSET:
-            # Convert deprecated compress_whitespace (bool) to whitespace (str).
-            if whitespace is not None:
-                raise Exception("cannot set both whitespace and compress_whitespace")
-            whitespace = "single" if compress_whitespace else "all"
-        if whitespace is None:
-            if loader and loader.whitespace:
-                whitespace = loader.whitespace
-            else:
-                # Whitespace defaults by filename.
-                if name.endswith(".html") or name.endswith(".js"):
-                    whitespace = "single"
-                else:
-                    whitespace = "all"
-        # Validate the whitespace setting.
-        filter_whitespace(whitespace, '')
-
-        if autoescape is not _UNSET:
-            self.autoescape = autoescape
-        elif loader:
-            self.autoescape = loader.autoescape
-        else:
-            self.autoescape = _DEFAULT_AUTOESCAPE
-
-        self.namespace = loader.namespace if loader else {}
-        reader = _TemplateReader(name, escape.native_str(template_string),
-                                 whitespace)
-        self.file = _File(self, _parse(reader, self))
-        self.code = self._generate_python(loader)
-        self.loader = loader
-        try:
-            # Under python2.5, the fake filename used here must match
-            # the module name used in __name__ below.
-            # The dont_inherit flag prevents template.py's future imports
-            # from being applied to the generated code.
-            self.compiled = compile(
-                escape.to_unicode(self.code),
-                "%s.generated.py" % self.name.replace('.', '_'),
-                "exec", dont_inherit=True)
-        except Exception:
-            formatted_code = _format_code(self.code).rstrip()
-            app_log.error("%s code:\n%s", self.name, formatted_code)
-            raise
-
-    def generate(self, **kwargs):
-        """Generate this template with the given arguments."""
-        namespace = {
-            "escape": escape.xhtml_escape,
-            "xhtml_escape": escape.xhtml_escape,
-            "url_escape": escape.url_escape,
-            "json_encode": escape.json_encode,
-            "squeeze": escape.squeeze,
-            "linkify": escape.linkify,
-            "datetime": datetime,
-            "_tt_utf8": escape.utf8,  # for internal use
-            "_tt_string_types": (unicode_type, bytes),
-            # __name__ and __loader__ allow the traceback mechanism to find
-            # the generated source code.
-            "__name__": self.name.replace('.', '_'),
-            "__loader__": ObjectDict(get_source=lambda name: self.code),
-        }
-        namespace.update(self.namespace)
-        namespace.update(kwargs)
-        exec_in(self.compiled, namespace)
-        execute = namespace["_tt_execute"]
-        # Clear the traceback module's cache of source data now that
-        # we've generated a new template (mainly for this module's
-        # unittests, where different tests reuse the same name).
-        linecache.clearcache()
-        return execute()
-
-    def _generate_python(self, loader):
-        buffer = StringIO()
-        try:
-            # named_blocks maps from names to _NamedBlock objects
-            named_blocks = {}
-            ancestors = self._get_ancestors(loader)
-            ancestors.reverse()
-            for ancestor in ancestors:
-                ancestor.find_named_blocks(loader, named_blocks)
-            writer = _CodeWriter(buffer, named_blocks, loader,
-                                 ancestors[0].template)
-            ancestors[0].generate(writer)
-            return buffer.getvalue()
-        finally:
-            buffer.close()
-
-    def _get_ancestors(self, loader):
-        ancestors = [self.file]
-        for chunk in self.file.body.chunks:
-            if isinstance(chunk, _ExtendsBlock):
-                if not loader:
-                    raise ParseError("{% extends %} block found, but no "
-                                     "template loader")
-                template = loader.load(chunk.name, self.name)
-                ancestors.extend(template._get_ancestors(loader))
-        return ancestors
-
-
-class BaseLoader(object):
-    """Base class for template loaders.
-
-    You must use a template loader to use template constructs like
-    ``{% extends %}`` and ``{% include %}``. The loader caches all
-    templates after they are loaded the first time.
-    """
-    def __init__(self, autoescape=_DEFAULT_AUTOESCAPE, namespace=None,
-                 whitespace=None):
-        """Construct a template loader.
-
-        :arg str autoescape: The name of a function in the template
-            namespace, such as "xhtml_escape", or ``None`` to disable
-            autoescaping by default.
-        :arg dict namespace: A dictionary to be added to the default template
-            namespace, or ``None``.
-        :arg str whitespace: A string specifying default behavior for
-            whitespace in templates; see `filter_whitespace` for options.
-            Default is "single" for files ending in ".html" and ".js" and
-            "all" for other files.
-
-        .. versionchanged:: 4.3
-           Added ``whitespace`` parameter.
-        """
-        self.autoescape = autoescape
-        self.namespace = namespace or {}
-        self.whitespace = whitespace
-        self.templates = {}
-        # self.lock protects self.templates.  It's a reentrant lock
-        # because templates may load other templates via `include` or
-        # `extends`.  Note that thanks to the GIL this code would be safe
-        # even without the lock, but could lead to wasted work as multiple
-        # threads tried to compile the same template simultaneously.
-        self.lock = threading.RLock()
-
-    def reset(self):
-        """Resets the cache of compiled templates."""
-        with self.lock:
-            self.templates = {}
-
-    def resolve_path(self, name, parent_path=None):
-        """Converts a possibly-relative path to absolute (used internally)."""
-        raise NotImplementedError()
-
-    def load(self, name, parent_path=None):
-        """Loads a template."""
-        name = self.resolve_path(name, parent_path=parent_path)
-        with self.lock:
-            if name not in self.templates:
-                self.templates[name] = self._create_template(name)
-            return self.templates[name]
-
-    def _create_template(self, name):
-        raise NotImplementedError()
-
-
-class Loader(BaseLoader):
-    """A template loader that loads from a single root directory.
-    """
-    def __init__(self, root_directory, **kwargs):
-        super(Loader, self).__init__(**kwargs)
-        self.root = os.path.abspath(root_directory)
-
-    def resolve_path(self, name, parent_path=None):
-        if parent_path and not parent_path.startswith("<") and \
-            not parent_path.startswith("/") and \
-                not name.startswith("/"):
-            current_path = os.path.join(self.root, parent_path)
-            file_dir = os.path.dirname(os.path.abspath(current_path))
-            relative_path = os.path.abspath(os.path.join(file_dir, name))
-            if relative_path.startswith(self.root):
-                name = relative_path[len(self.root) + 1:]
-        return name
-
-    def _create_template(self, name):
-        path = os.path.join(self.root, name)
-        with open(path, "rb") as f:
-            template = Template(f.read(), name=name, loader=self)
-            return template
-
-
-class DictLoader(BaseLoader):
-    """A template loader that loads from a dictionary."""
-    def __init__(self, dict, **kwargs):
-        super(DictLoader, self).__init__(**kwargs)
-        self.dict = dict
-
-    def resolve_path(self, name, parent_path=None):
-        if parent_path and not parent_path.startswith("<") and \
-            not parent_path.startswith("/") and \
-                not name.startswith("/"):
-            file_dir = posixpath.dirname(parent_path)
-            name = posixpath.normpath(posixpath.join(file_dir, name))
-        return name
-
-    def _create_template(self, name):
-        return Template(self.dict[name], name=name, loader=self)
-
-
-class _Node(object):
-    def each_child(self):
-        return ()
-
-    def generate(self, writer):
-        raise NotImplementedError()
-
-    def find_named_blocks(self, loader, named_blocks):
-        for child in self.each_child():
-            child.find_named_blocks(loader, named_blocks)
-
-
-class _File(_Node):
-    def __init__(self, template, body):
-        self.template = template
-        self.body = body
-        self.line = 0
-
-    def generate(self, writer):
-        writer.write_line("def _tt_execute():", self.line)
-        with writer.indent():
-            writer.write_line("_tt_buffer = []", self.line)
-            writer.write_line("_tt_append = _tt_buffer.append", self.line)
-            self.body.generate(writer)
-            writer.write_line("return _tt_utf8('').join(_tt_buffer)", self.line)
-
-    def each_child(self):
-        return (self.body,)
-
-
-class _ChunkList(_Node):
-    def __init__(self, chunks):
-        self.chunks = chunks
-
-    def generate(self, writer):
-        for chunk in self.chunks:
-            chunk.generate(writer)
-
-    def each_child(self):
-        return self.chunks
-
-
-class _NamedBlock(_Node):
-    def __init__(self, name, body, template, line):
-        self.name = name
-        self.body = body
-        self.template = template
-        self.line = line
-
-    def each_child(self):
-        return (self.body,)
-
-    def generate(self, writer):
-        block = writer.named_blocks[self.name]
-        with writer.include(block.template, self.line):
-            block.body.generate(writer)
-
-    def find_named_blocks(self, loader, named_blocks):
-        named_blocks[self.name] = self
-        _Node.find_named_blocks(self, loader, named_blocks)
-
-
-class _ExtendsBlock(_Node):
-    def __init__(self, name):
-        self.name = name
-
-
-class _IncludeBlock(_Node):
-    def __init__(self, name, reader, line):
-        self.name = name
-        self.template_name = reader.name
-        self.line = line
-
-    def find_named_blocks(self, loader, named_blocks):
-        included = loader.load(self.name, self.template_name)
-        included.file.find_named_blocks(loader, named_blocks)
-
-    def generate(self, writer):
-        included = writer.loader.load(self.name, self.template_name)
-        with writer.include(included, self.line):
-            included.file.body.generate(writer)
-
-
-class _ApplyBlock(_Node):
-    def __init__(self, method, line, body=None):
-        self.method = method
-        self.line = line
-        self.body = body
-
-    def each_child(self):
-        return (self.body,)
-
-    def generate(self, writer):
-        method_name = "_tt_apply%d" % writer.apply_counter
-        writer.apply_counter += 1
-        writer.write_line("def %s():" % method_name, self.line)
-        with writer.indent():
-            writer.write_line("_tt_buffer = []", self.line)
-            writer.write_line("_tt_append = _tt_buffer.append", self.line)
-            self.body.generate(writer)
-            writer.write_line("return _tt_utf8('').join(_tt_buffer)", self.line)
-        writer.write_line("_tt_append(_tt_utf8(%s(%s())))" % (
-            self.method, method_name), self.line)
-
-
-class _ControlBlock(_Node):
-    def __init__(self, statement, line, body=None):
-        self.statement = statement
-        self.line = line
-        self.body = body
-
-    def each_child(self):
-        return (self.body,)
-
-    def generate(self, writer):
-        writer.write_line("%s:" % self.statement, self.line)
-        with writer.indent():
-            self.body.generate(writer)
-            # Just in case the body was empty
-            writer.write_line("pass", self.line)
-
-
-class _IntermediateControlBlock(_Node):
-    def __init__(self, statement, line):
-        self.statement = statement
-        self.line = line
-
-    def generate(self, writer):
-        # In case the previous block was empty
-        writer.write_line("pass", self.line)
-        writer.write_line("%s:" % self.statement, self.line, writer.indent_size() - 1)
-
-
-class _Statement(_Node):
-    def __init__(self, statement, line):
-        self.statement = statement
-        self.line = line
-
-    def generate(self, writer):
-        writer.write_line(self.statement, self.line)
-
-
-class _Expression(_Node):
-    def __init__(self, expression, line, raw=False):
-        self.expression = expression
-        self.line = line
-        self.raw = raw
-
-    def generate(self, writer):
-        writer.write_line("_tt_tmp = %s" % self.expression, self.line)
-        writer.write_line("if isinstance(_tt_tmp, _tt_string_types):"
-                          " _tt_tmp = _tt_utf8(_tt_tmp)", self.line)
-        writer.write_line("else: _tt_tmp = _tt_utf8(str(_tt_tmp))", self.line)
-        if not self.raw and writer.current_template.autoescape is not None:
-            # In python3 functions like xhtml_escape return unicode,
-            # so we have to convert to utf8 again.
-            writer.write_line("_tt_tmp = _tt_utf8(%s(_tt_tmp))" %
-                              writer.current_template.autoescape, self.line)
-        writer.write_line("_tt_append(_tt_tmp)", self.line)
-
-
-class _Module(_Expression):
-    def __init__(self, expression, line):
-        super(_Module, self).__init__("_tt_modules." + expression, line,
-                                      raw=True)
-
-
-class _Text(_Node):
-    def __init__(self, value, line, whitespace):
-        self.value = value
-        self.line = line
-        self.whitespace = whitespace
-
-    def generate(self, writer):
-        value = self.value
-
-        # Compress whitespace if requested, with a crude heuristic to avoid
-        # altering preformatted whitespace.
-        if "<pre>" not in value:
-            value = filter_whitespace(self.whitespace, value)
-
-        if value:
-            writer.write_line('_tt_append(%r)' % escape.utf8(value), self.line)
-
-
-class ParseError(Exception):
-    """Raised for template syntax errors.
-
-    ``ParseError`` instances have ``filename`` and ``lineno`` attributes
-    indicating the position of the error.
-
-    .. versionchanged:: 4.3
-       Added ``filename`` and ``lineno`` attributes.
-    """
-    def __init__(self, message, filename=None, lineno=0):
-        self.message = message
-        # The names "filename" and "lineno" are chosen for consistency
-        # with python SyntaxError.
-        self.filename = filename
-        self.lineno = lineno
-
-    def __str__(self):
-        return '%s at %s:%d' % (self.message, self.filename, self.lineno)
-
-
-class _CodeWriter(object):
-    def __init__(self, file, named_blocks, loader, current_template):
-        self.file = file
-        self.named_blocks = named_blocks
-        self.loader = loader
-        self.current_template = current_template
-        self.apply_counter = 0
-        self.include_stack = []
-        self._indent = 0
-
-    def indent_size(self):
-        return self._indent
-
-    def indent(self):
-        class Indenter(object):
-            def __enter__(_):
-                self._indent += 1
-                return self
-
-            def __exit__(_, *args):
-                assert self._indent > 0
-                self._indent -= 1
-
-        return Indenter()
-
-    def include(self, template, line):
-        self.include_stack.append((self.current_template, line))
-        self.current_template = template
-
-        class IncludeTemplate(object):
-            def __enter__(_):
-                return self
-
-            def __exit__(_, *args):
-                self.current_template = self.include_stack.pop()[0]
-
-        return IncludeTemplate()
-
-    def write_line(self, line, line_number, indent=None):
-        if indent is None:
-            indent = self._indent
-        line_comment = '  # %s:%d' % (self.current_template.name, line_number)
-        if self.include_stack:
-            ancestors = ["%s:%d" % (tmpl.name, lineno)
-                         for (tmpl, lineno) in self.include_stack]
-            line_comment += ' (via %s)' % ', '.join(reversed(ancestors))
-        print("    " * indent + line + line_comment, file=self.file)
-
-
-class _TemplateReader(object):
-    def __init__(self, name, text, whitespace):
-        self.name = name
-        self.text = text
-        self.whitespace = whitespace
-        self.line = 1
-        self.pos = 0
-
-    def find(self, needle, start=0, end=None):
-        assert start >= 0, start
-        pos = self.pos
-        start += pos
-        if end is None:
-            index = self.text.find(needle, start)
-        else:
-            end += pos
-            assert end >= start
-            index = self.text.find(needle, start, end)
-        if index != -1:
-            index -= pos
-        return index
-
-    def consume(self, count=None):
-        if count is None:
-            count = len(self.text) - self.pos
-        newpos = self.pos + count
-        self.line += self.text.count("\n", self.pos, newpos)
-        s = self.text[self.pos:newpos]
-        self.pos = newpos
-        return s
-
-    def remaining(self):
-        return len(self.text) - self.pos
-
-    def __len__(self):
-        return self.remaining()
-
-    def __getitem__(self, key):
-        if type(key) is slice:
-            size = len(self)
-            start, stop, step = key.indices(size)
-            if start is None:
-                start = self.pos
-            else:
-                start += self.pos
-            if stop is not None:
-                stop += self.pos
-            return self.text[slice(start, stop, step)]
-        elif key < 0:
-            return self.text[key]
-        else:
-            return self.text[self.pos + key]
-
-    def __str__(self):
-        return self.text[self.pos:]
-
-    def raise_parse_error(self, msg):
-        raise ParseError(msg, self.name, self.line)
-
-
-def _format_code(code):
-    lines = code.splitlines()
-    format = "%%%dd  %%s\n" % len(repr(len(lines) + 1))
-    return "".join([format % (i + 1, line) for (i, line) in enumerate(lines)])
-
-
-def _parse(reader, template, in_block=None, in_loop=None):
-    body = _ChunkList([])
-    while True:
-        # Find next template directive
-        curly = 0
-        while True:
-            curly = reader.find("{", curly)
-            if curly == -1 or curly + 1 == reader.remaining():
-                # EOF
-                if in_block:
-                    reader.raise_parse_error(
-                        "Missing {%% end %%} block for %s" % in_block)
-                body.chunks.append(_Text(reader.consume(), reader.line,
-                                         reader.whitespace))
-                return body
-            # If the first curly brace is not the start of a special token,
-            # start searching from the character after it
-            if reader[curly + 1] not in ("{", "%", "#"):
-                curly += 1
-                continue
-            # When there are more than 2 curlies in a row, use the
-            # innermost ones.  This is useful when generating languages
-            # like latex where curlies are also meaningful
-            if (curly + 2 < reader.remaining() and
-                    reader[curly + 1] == '{' and reader[curly + 2] == '{'):
-                curly += 1
-                continue
-            break
-
-        # Append any text before the special token
-        if curly > 0:
-            cons = reader.consume(curly)
-            body.chunks.append(_Text(cons, reader.line,
-                                     reader.whitespace))
-
-        start_brace = reader.consume(2)
-        line = reader.line
-
-        # Template directives may be escaped as "{{!" or "{%!".
-        # In this case output the braces and consume the "!".
-        # This is especially useful in conjunction with jquery templates,
-        # which also use double braces.
-        if reader.remaining() and reader[0] == "!":
-            reader.consume(1)
-            body.chunks.append(_Text(start_brace, line,
-                                     reader.whitespace))
-            continue
-
-        # Comment
-        if start_brace == "{#":
-            end = reader.find("#}")
-            if end == -1:
-                reader.raise_parse_error("Missing end comment #}")
-            contents = reader.consume(end).strip()
-            reader.consume(2)
-            continue
-
-        # Expression
-        if start_brace == "{{":
-            end = reader.find("}}")
-            if end == -1:
-                reader.raise_parse_error("Missing end expression }}")
-            contents = reader.consume(end).strip()
-            reader.consume(2)
-            if not contents:
-                reader.raise_parse_error("Empty expression")
-            body.chunks.append(_Expression(contents, line))
-            continue
-
-        # Block
-        assert start_brace == "{%", start_brace
-        end = reader.find("%}")
-        if end == -1:
-            reader.raise_parse_error("Missing end block %}")
-        contents = reader.consume(end).strip()
-        reader.consume(2)
-        if not contents:
-            reader.raise_parse_error("Empty block tag ({% %})")
-
-        operator, space, suffix = contents.partition(" ")
-        suffix = suffix.strip()
-
-        # Intermediate ("else", "elif", etc) blocks
-        intermediate_blocks = {
-            "else": set(["if", "for", "while", "try"]),
-            "elif": set(["if"]),
-            "except": set(["try"]),
-            "finally": set(["try"]),
-        }
-        allowed_parents = intermediate_blocks.get(operator)
-        if allowed_parents is not None:
-            if not in_block:
-                reader.raise_parse_error("%s outside %s block" %
-                                         (operator, allowed_parents))
-            if in_block not in allowed_parents:
-                reader.raise_parse_error(
-                    "%s block cannot be attached to %s block" %
-                    (operator, in_block))
-            body.chunks.append(_IntermediateControlBlock(contents, line))
-            continue
-
-        # End tag
-        elif operator == "end":
-            if not in_block:
-                reader.raise_parse_error("Extra {% end %} block")
-            return body
-
-        elif operator in ("extends", "include", "set", "import", "from",
-                          "comment", "autoescape", "whitespace", "raw",
-                          "module"):
-            if operator == "comment":
-                continue
-            if operator == "extends":
-                suffix = suffix.strip('"').strip("'")
-                if not suffix:
-                    reader.raise_parse_error("extends missing file path")
-                block = _ExtendsBlock(suffix)
-            elif operator in ("import", "from"):
-                if not suffix:
-                    reader.raise_parse_error("import missing statement")
-                block = _Statement(contents, line)
-            elif operator == "include":
-                suffix = suffix.strip('"').strip("'")
-                if not suffix:
-                    reader.raise_parse_error("include missing file path")
-                block = _IncludeBlock(suffix, reader, line)
-            elif operator == "set":
-                if not suffix:
-                    reader.raise_parse_error("set missing statement")
-                block = _Statement(suffix, line)
-            elif operator == "autoescape":
-                fn = suffix.strip()
-                if fn == "None":
-                    fn = None
-                template.autoescape = fn
-                continue
-            elif operator == "whitespace":
-                mode = suffix.strip()
-                # Validate the selected mode
-                filter_whitespace(mode, '')
-                reader.whitespace = mode
-                continue
-            elif operator == "raw":
-                block = _Expression(suffix, line, raw=True)
-            elif operator == "module":
-                block = _Module(suffix, line)
-            body.chunks.append(block)
-            continue
-
-        elif operator in ("apply", "block", "try", "if", "for", "while"):
-            # parse inner body recursively
-            if operator in ("for", "while"):
-                block_body = _parse(reader, template, operator, operator)
-            elif operator == "apply":
-                # apply creates a nested function so syntactically it's not
-                # in the loop.
-                block_body = _parse(reader, template, operator, None)
-            else:
-                block_body = _parse(reader, template, operator, in_loop)
-
-            if operator == "apply":
-                if not suffix:
-                    reader.raise_parse_error("apply missing method name")
-                block = _ApplyBlock(suffix, line, block_body)
-            elif operator == "block":
-                if not suffix:
-                    reader.raise_parse_error("block missing name")
-                block = _NamedBlock(suffix, block_body, template, line)
-            else:
-                block = _ControlBlock(contents, line, block_body)
-            body.chunks.append(block)
-            continue
-
-        elif operator in ("break", "continue"):
-            if not in_loop:
-                reader.raise_parse_error("%s outside %s block" %
-                                         (operator, set(["for", "while"])))
-            body.chunks.append(_Statement(contents, line))
-            continue
-
-        else:
-            reader.raise_parse_error("unknown operator: %r" % operator)
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""A simple template system that compiles templates to Python code. 
+ 
+Basic usage looks like:: 
+ 
+    t = template.Template("<html>{{ myvalue }}</html>") 
+    print(t.generate(myvalue="XXX")) 
+ 
+`Loader` is a class that loads templates from a root directory and caches 
+the compiled templates:: 
+ 
+    loader = template.Loader("/home/btaylor") 
+    print(loader.load("test.html").generate(myvalue="XXX")) 
+ 
+We compile all templates to raw Python. Error-reporting is currently... uh, 
+interesting. Syntax for the templates:: 
+ 
+    ### base.html 
+    <html> 
+      <head> 
+        <title>{% block title %}Default title{% end %}</title> 
+      </head> 
+      <body> 
+        <ul> 
+          {% for student in students %} 
+            {% block student %} 
+              <li>{{ escape(student.name) }}</li> 
+            {% end %} 
+          {% end %} 
+        </ul> 
+      </body> 
+    </html> 
+ 
+    ### bold.html 
+    {% extends "base.html" %} 
+ 
+    {% block title %}A bolder title{% end %} 
+ 
+    {% block student %} 
+      <li><span style="bold">{{ escape(student.name) }}</span></li> 
+    {% end %} 
+ 
+Unlike most other template systems, we do not put any restrictions on the 
+expressions you can include in your statements. ``if`` and ``for`` blocks get 
+translated exactly into Python, so you can do complex expressions like:: 
+ 
+   {% for student in [p for p in people if p.student and p.age > 23] %} 
+     <li>{{ escape(student.name) }}</li> 
+   {% end %} 
+ 
+Translating directly to Python means you can apply functions to expressions 
+easily, like the ``escape()`` function in the examples above. You can pass 
+functions in to your template just like any other variable 
+(In a `.RequestHandler`, override `.RequestHandler.get_template_namespace`):: 
+ 
+   ### Python code 
+   def add(x, y): 
+      return x + y 
+   template.execute(add=add) 
+ 
+   ### The template 
+   {{ add(1, 2) }} 
+ 
+We provide the functions `escape() <.xhtml_escape>`, `.url_escape()`, 
+`.json_encode()`, and `.squeeze()` to all templates by default. 
+ 
+Typical applications do not create `Template` or `Loader` instances by 
+hand, but instead use the `~.RequestHandler.render` and 
+`~.RequestHandler.render_string` methods of 
+`tornado.web.RequestHandler`, which load templates automatically based 
+on the ``template_path`` `.Application` setting. 
+ 
+Variable names beginning with ``_tt_`` are reserved by the template 
+system and should not be used by application code. 
+ 
+Syntax Reference 
+---------------- 
+ 
+Template expressions are surrounded by double curly braces: ``{{ ... }}``. 
+The contents may be any python expression, which will be escaped according 
+to the current autoescape setting and inserted into the output.  Other 
+template directives use ``{% %}``. 
+ 
+To comment out a section so that it is omitted from the output, surround it 
+with ``{# ... #}``. 
+ 
+These tags may be escaped as ``{{!``, ``{%!``, and ``{#!`` 
+if you need to include a literal ``{{``, ``{%``, or ``{#`` in the output. 
+ 
+ 
+``{% apply *function* %}...{% end %}`` 
+    Applies a function to the output of all template code between ``apply`` 
+    and ``end``:: 
+ 
+        {% apply linkify %}{{name}} said: {{message}}{% end %} 
+ 
+    Note that as an implementation detail apply blocks are implemented 
+    as nested functions and thus may interact strangely with variables 
+    set via ``{% set %}``, or the use of ``{% break %}`` or ``{% continue %}`` 
+    within loops. 
+ 
+``{% autoescape *function* %}`` 
+    Sets the autoescape mode for the current file.  This does not affect 
+    other files, even those referenced by ``{% include %}``.  Note that 
+    autoescaping can also be configured globally, at the `.Application` 
+    or `Loader`.:: 
+ 
+        {% autoescape xhtml_escape %} 
+        {% autoescape None %} 
+ 
+``{% block *name* %}...{% end %}`` 
+    Indicates a named, replaceable block for use with ``{% extends %}``. 
+    Blocks in the parent template will be replaced with the contents of 
+    the same-named block in a child template.:: 
+ 
+        <!-- base.html --> 
+        <title>{% block title %}Default title{% end %}</title> 
+ 
+        <!-- mypage.html --> 
+        {% extends "base.html" %} 
+        {% block title %}My page title{% end %} 
+ 
+``{% comment ... %}`` 
+    A comment which will be removed from the template output.  Note that 
+    there is no ``{% end %}`` tag; the comment goes from the word ``comment`` 
+    to the closing ``%}`` tag. 
+ 
+``{% extends *filename* %}`` 
+    Inherit from another template.  Templates that use ``extends`` should 
+    contain one or more ``block`` tags to replace content from the parent 
+    template.  Anything in the child template not contained in a ``block`` 
+    tag will be ignored.  For an example, see the ``{% block %}`` tag. 
+ 
+``{% for *var* in *expr* %}...{% end %}`` 
+    Same as the python ``for`` statement.  ``{% break %}`` and 
+    ``{% continue %}`` may be used inside the loop. 
+ 
+``{% from *x* import *y* %}`` 
+    Same as the python ``import`` statement. 
+ 
+``{% if *condition* %}...{% elif *condition* %}...{% else %}...{% end %}`` 
+    Conditional statement - outputs the first section whose condition is 
+    true.  (The ``elif`` and ``else`` sections are optional) 
+ 
+``{% import *module* %}`` 
+    Same as the python ``import`` statement. 
+ 
+``{% include *filename* %}`` 
+    Includes another template file.  The included file can see all the local 
+    variables as if it were copied directly to the point of the ``include`` 
+    directive (the ``{% autoescape %}`` directive is an exception). 
+    Alternately, ``{% module Template(filename, **kwargs) %}`` may be used 
+    to include another template with an isolated namespace. 
+ 
+``{% module *expr* %}`` 
+    Renders a `~tornado.web.UIModule`.  The output of the ``UIModule`` is 
+    not escaped:: 
+ 
+        {% module Template("foo.html", arg=42) %} 
+ 
+    ``UIModules`` are a feature of the `tornado.web.RequestHandler` 
+    class (and specifically its ``render`` method) and will not work 
+    when the template system is used on its own in other contexts. 
+ 
+``{% raw *expr* %}`` 
+    Outputs the result of the given expression without autoescaping. 
+ 
+``{% set *x* = *y* %}`` 
+    Sets a local variable. 
+ 
+``{% try %}...{% except %}...{% else %}...{% finally %}...{% end %}`` 
+    Same as the python ``try`` statement. 
+ 
+``{% while *condition* %}... {% end %}`` 
+    Same as the python ``while`` statement.  ``{% break %}`` and 
+    ``{% continue %}`` may be used inside the loop. 
+ 
+``{% whitespace *mode* %}`` 
+    Sets the whitespace mode for the remainder of the current file 
+    (or until the next ``{% whitespace %}`` directive). See 
+    `filter_whitespace` for available options. New in Tornado 4.3. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import datetime 
+import linecache 
+import os.path 
+import posixpath 
+import re 
+import threading 
+ 
+from tornado import escape 
+from tornado.log import app_log 
+from tornado.util import ObjectDict, exec_in, unicode_type, PY3 
+ 
+if PY3: 
+    from io import StringIO 
+else: 
+    from cStringIO import StringIO 
+ 
+_DEFAULT_AUTOESCAPE = "xhtml_escape" 
+_UNSET = object() 
+ 
+ 
+def filter_whitespace(mode, text): 
+    """Transform whitespace in ``text`` according to ``mode``. 
+ 
+    Available modes are: 
+ 
+    * ``all``: Return all whitespace unmodified. 
+    * ``single``: Collapse consecutive whitespace with a single whitespace 
+      character, preserving newlines. 
+    * ``oneline``: Collapse all runs of whitespace into a single space 
+      character, removing all newlines in the process. 
+ 
+    .. versionadded:: 4.3 
+    """ 
+    if mode == 'all': 
+        return text 
+    elif mode == 'single': 
+        text = re.sub(r"([\t ]+)", " ", text) 
+        text = re.sub(r"(\s*\n\s*)", "\n", text) 
+        return text 
+    elif mode == 'oneline': 
+        return re.sub(r"(\s+)", " ", text) 
+    else: 
+        raise Exception("invalid whitespace mode %s" % mode) 
+ 
+ 
+class Template(object): 
+    """A compiled template. 
+ 
+    We compile into Python from the given template_string. You can generate 
+    the template from variables with generate(). 
+    """ 
+    # note that the constructor's signature is not extracted with 
+    # autodoc because _UNSET looks like garbage.  When changing 
+    # this signature update website/sphinx/template.rst too. 
+    def __init__(self, template_string, name="<string>", loader=None, 
+                 compress_whitespace=_UNSET, autoescape=_UNSET, 
+                 whitespace=None): 
+        """Construct a Template. 
+ 
+        :arg str template_string: the contents of the template file. 
+        :arg str name: the filename from which the template was loaded 
+            (used for error message). 
+        :arg tornado.template.BaseLoader loader: the `~tornado.template.BaseLoader` responsible for this template, 
+            used to resolve ``{% include %}`` and ``{% extend %}`` 
+            directives. 
+        :arg bool compress_whitespace: Deprecated since Tornado 4.3. 
+            Equivalent to ``whitespace="single"`` if true and 
+            ``whitespace="all"`` if false. 
+        :arg str autoescape: The name of a function in the template 
+            namespace, or ``None`` to disable escaping by default. 
+        :arg str whitespace: A string specifying treatment of whitespace; 
+            see `filter_whitespace` for options. 
+ 
+        .. versionchanged:: 4.3 
+           Added ``whitespace`` parameter; deprecated ``compress_whitespace``. 
+        """ 
+        self.name = escape.native_str(name) 
+ 
+        if compress_whitespace is not _UNSET: 
+            # Convert deprecated compress_whitespace (bool) to whitespace (str). 
+            if whitespace is not None: 
+                raise Exception("cannot set both whitespace and compress_whitespace") 
+            whitespace = "single" if compress_whitespace else "all" 
+        if whitespace is None: 
+            if loader and loader.whitespace: 
+                whitespace = loader.whitespace 
+            else: 
+                # Whitespace defaults by filename. 
+                if name.endswith(".html") or name.endswith(".js"): 
+                    whitespace = "single" 
+                else: 
+                    whitespace = "all" 
+        # Validate the whitespace setting. 
+        filter_whitespace(whitespace, '') 
+ 
+        if autoescape is not _UNSET: 
+            self.autoescape = autoescape 
+        elif loader: 
+            self.autoescape = loader.autoescape 
+        else: 
+            self.autoescape = _DEFAULT_AUTOESCAPE 
+ 
+        self.namespace = loader.namespace if loader else {} 
+        reader = _TemplateReader(name, escape.native_str(template_string), 
+                                 whitespace) 
+        self.file = _File(self, _parse(reader, self)) 
+        self.code = self._generate_python(loader) 
+        self.loader = loader 
+        try: 
+            # Under python2.5, the fake filename used here must match 
+            # the module name used in __name__ below. 
+            # The dont_inherit flag prevents template.py's future imports 
+            # from being applied to the generated code. 
+            self.compiled = compile( 
+                escape.to_unicode(self.code), 
+                "%s.generated.py" % self.name.replace('.', '_'), 
+                "exec", dont_inherit=True) 
+        except Exception: 
+            formatted_code = _format_code(self.code).rstrip() 
+            app_log.error("%s code:\n%s", self.name, formatted_code) 
+            raise 
+ 
+    def generate(self, **kwargs): 
+        """Generate this template with the given arguments.""" 
+        namespace = { 
+            "escape": escape.xhtml_escape, 
+            "xhtml_escape": escape.xhtml_escape, 
+            "url_escape": escape.url_escape, 
+            "json_encode": escape.json_encode, 
+            "squeeze": escape.squeeze, 
+            "linkify": escape.linkify, 
+            "datetime": datetime, 
+            "_tt_utf8": escape.utf8,  # for internal use 
+            "_tt_string_types": (unicode_type, bytes), 
+            # __name__ and __loader__ allow the traceback mechanism to find 
+            # the generated source code. 
+            "__name__": self.name.replace('.', '_'), 
+            "__loader__": ObjectDict(get_source=lambda name: self.code), 
+        } 
+        namespace.update(self.namespace) 
+        namespace.update(kwargs) 
+        exec_in(self.compiled, namespace) 
+        execute = namespace["_tt_execute"] 
+        # Clear the traceback module's cache of source data now that 
+        # we've generated a new template (mainly for this module's 
+        # unittests, where different tests reuse the same name). 
+        linecache.clearcache() 
+        return execute() 
+ 
+    def _generate_python(self, loader): 
+        buffer = StringIO() 
+        try: 
+            # named_blocks maps from names to _NamedBlock objects 
+            named_blocks = {} 
+            ancestors = self._get_ancestors(loader) 
+            ancestors.reverse() 
+            for ancestor in ancestors: 
+                ancestor.find_named_blocks(loader, named_blocks) 
+            writer = _CodeWriter(buffer, named_blocks, loader, 
+                                 ancestors[0].template) 
+            ancestors[0].generate(writer) 
+            return buffer.getvalue() 
+        finally: 
+            buffer.close() 
+ 
+    def _get_ancestors(self, loader): 
+        ancestors = [self.file] 
+        for chunk in self.file.body.chunks: 
+            if isinstance(chunk, _ExtendsBlock): 
+                if not loader: 
+                    raise ParseError("{% extends %} block found, but no " 
+                                     "template loader") 
+                template = loader.load(chunk.name, self.name) 
+                ancestors.extend(template._get_ancestors(loader)) 
+        return ancestors 
+ 
+ 
+class BaseLoader(object): 
+    """Base class for template loaders. 
+ 
+    You must use a template loader to use template constructs like 
+    ``{% extends %}`` and ``{% include %}``. The loader caches all 
+    templates after they are loaded the first time. 
+    """ 
+    def __init__(self, autoescape=_DEFAULT_AUTOESCAPE, namespace=None, 
+                 whitespace=None): 
+        """Construct a template loader. 
+ 
+        :arg str autoescape: The name of a function in the template 
+            namespace, such as "xhtml_escape", or ``None`` to disable 
+            autoescaping by default. 
+        :arg dict namespace: A dictionary to be added to the default template 
+            namespace, or ``None``. 
+        :arg str whitespace: A string specifying default behavior for 
+            whitespace in templates; see `filter_whitespace` for options. 
+            Default is "single" for files ending in ".html" and ".js" and 
+            "all" for other files. 
+ 
+        .. versionchanged:: 4.3 
+           Added ``whitespace`` parameter. 
+        """ 
+        self.autoescape = autoescape 
+        self.namespace = namespace or {} 
+        self.whitespace = whitespace 
+        self.templates = {} 
+        # self.lock protects self.templates.  It's a reentrant lock 
+        # because templates may load other templates via `include` or 
+        # `extends`.  Note that thanks to the GIL this code would be safe 
+        # even without the lock, but could lead to wasted work as multiple 
+        # threads tried to compile the same template simultaneously. 
+        self.lock = threading.RLock() 
+ 
+    def reset(self): 
+        """Resets the cache of compiled templates.""" 
+        with self.lock: 
+            self.templates = {} 
+ 
+    def resolve_path(self, name, parent_path=None): 
+        """Converts a possibly-relative path to absolute (used internally).""" 
+        raise NotImplementedError() 
+ 
+    def load(self, name, parent_path=None): 
+        """Loads a template.""" 
+        name = self.resolve_path(name, parent_path=parent_path) 
+        with self.lock: 
+            if name not in self.templates: 
+                self.templates[name] = self._create_template(name) 
+            return self.templates[name] 
+ 
+    def _create_template(self, name): 
+        raise NotImplementedError() 
+ 
+ 
+class Loader(BaseLoader): 
+    """A template loader that loads from a single root directory. 
+    """ 
+    def __init__(self, root_directory, **kwargs): 
+        super(Loader, self).__init__(**kwargs) 
+        self.root = os.path.abspath(root_directory) 
+ 
+    def resolve_path(self, name, parent_path=None): 
+        if parent_path and not parent_path.startswith("<") and \ 
+            not parent_path.startswith("/") and \ 
+                not name.startswith("/"): 
+            current_path = os.path.join(self.root, parent_path) 
+            file_dir = os.path.dirname(os.path.abspath(current_path)) 
+            relative_path = os.path.abspath(os.path.join(file_dir, name)) 
+            if relative_path.startswith(self.root): 
+                name = relative_path[len(self.root) + 1:] 
+        return name 
+ 
+    def _create_template(self, name): 
+        path = os.path.join(self.root, name) 
+        with open(path, "rb") as f: 
+            template = Template(f.read(), name=name, loader=self) 
+            return template 
+ 
+ 
+class DictLoader(BaseLoader): 
+    """A template loader that loads from a dictionary.""" 
+    def __init__(self, dict, **kwargs): 
+        super(DictLoader, self).__init__(**kwargs) 
+        self.dict = dict 
+ 
+    def resolve_path(self, name, parent_path=None): 
+        if parent_path and not parent_path.startswith("<") and \ 
+            not parent_path.startswith("/") and \ 
+                not name.startswith("/"): 
+            file_dir = posixpath.dirname(parent_path) 
+            name = posixpath.normpath(posixpath.join(file_dir, name)) 
+        return name 
+ 
+    def _create_template(self, name): 
+        return Template(self.dict[name], name=name, loader=self) 
+ 
+ 
+class _Node(object): 
+    def each_child(self): 
+        return () 
+ 
+    def generate(self, writer): 
+        raise NotImplementedError() 
+ 
+    def find_named_blocks(self, loader, named_blocks): 
+        for child in self.each_child(): 
+            child.find_named_blocks(loader, named_blocks) 
+ 
+ 
+class _File(_Node): 
+    def __init__(self, template, body): 
+        self.template = template 
+        self.body = body 
+        self.line = 0 
+ 
+    def generate(self, writer): 
+        writer.write_line("def _tt_execute():", self.line) 
+        with writer.indent(): 
+            writer.write_line("_tt_buffer = []", self.line) 
+            writer.write_line("_tt_append = _tt_buffer.append", self.line) 
+            self.body.generate(writer) 
+            writer.write_line("return _tt_utf8('').join(_tt_buffer)", self.line) 
+ 
+    def each_child(self): 
+        return (self.body,) 
+ 
+ 
+class _ChunkList(_Node): 
+    def __init__(self, chunks): 
+        self.chunks = chunks 
+ 
+    def generate(self, writer): 
+        for chunk in self.chunks: 
+            chunk.generate(writer) 
+ 
+    def each_child(self): 
+        return self.chunks 
+ 
+ 
+class _NamedBlock(_Node): 
+    def __init__(self, name, body, template, line): 
+        self.name = name 
+        self.body = body 
+        self.template = template 
+        self.line = line 
+ 
+    def each_child(self): 
+        return (self.body,) 
+ 
+    def generate(self, writer): 
+        block = writer.named_blocks[self.name] 
+        with writer.include(block.template, self.line): 
+            block.body.generate(writer) 
+ 
+    def find_named_blocks(self, loader, named_blocks): 
+        named_blocks[self.name] = self 
+        _Node.find_named_blocks(self, loader, named_blocks) 
+ 
+ 
+class _ExtendsBlock(_Node): 
+    def __init__(self, name): 
+        self.name = name 
+ 
+ 
+class _IncludeBlock(_Node): 
+    def __init__(self, name, reader, line): 
+        self.name = name 
+        self.template_name = reader.name 
+        self.line = line 
+ 
+    def find_named_blocks(self, loader, named_blocks): 
+        included = loader.load(self.name, self.template_name) 
+        included.file.find_named_blocks(loader, named_blocks) 
+ 
+    def generate(self, writer): 
+        included = writer.loader.load(self.name, self.template_name) 
+        with writer.include(included, self.line): 
+            included.file.body.generate(writer) 
+ 
+ 
+class _ApplyBlock(_Node): 
+    def __init__(self, method, line, body=None): 
+        self.method = method 
+        self.line = line 
+        self.body = body 
+ 
+    def each_child(self): 
+        return (self.body,) 
+ 
+    def generate(self, writer): 
+        method_name = "_tt_apply%d" % writer.apply_counter 
+        writer.apply_counter += 1 
+        writer.write_line("def %s():" % method_name, self.line) 
+        with writer.indent(): 
+            writer.write_line("_tt_buffer = []", self.line) 
+            writer.write_line("_tt_append = _tt_buffer.append", self.line) 
+            self.body.generate(writer) 
+            writer.write_line("return _tt_utf8('').join(_tt_buffer)", self.line) 
+        writer.write_line("_tt_append(_tt_utf8(%s(%s())))" % ( 
+            self.method, method_name), self.line) 
+ 
+ 
+class _ControlBlock(_Node): 
+    def __init__(self, statement, line, body=None): 
+        self.statement = statement 
+        self.line = line 
+        self.body = body 
+ 
+    def each_child(self): 
+        return (self.body,) 
+ 
+    def generate(self, writer): 
+        writer.write_line("%s:" % self.statement, self.line) 
+        with writer.indent(): 
+            self.body.generate(writer) 
+            # Just in case the body was empty 
+            writer.write_line("pass", self.line) 
+ 
+ 
+class _IntermediateControlBlock(_Node): 
+    def __init__(self, statement, line): 
+        self.statement = statement 
+        self.line = line 
+ 
+    def generate(self, writer): 
+        # In case the previous block was empty 
+        writer.write_line("pass", self.line) 
+        writer.write_line("%s:" % self.statement, self.line, writer.indent_size() - 1) 
+ 
+ 
+class _Statement(_Node): 
+    def __init__(self, statement, line): 
+        self.statement = statement 
+        self.line = line 
+ 
+    def generate(self, writer): 
+        writer.write_line(self.statement, self.line) 
+ 
+ 
+class _Expression(_Node): 
+    def __init__(self, expression, line, raw=False): 
+        self.expression = expression 
+        self.line = line 
+        self.raw = raw 
+ 
+    def generate(self, writer): 
+        writer.write_line("_tt_tmp = %s" % self.expression, self.line) 
+        writer.write_line("if isinstance(_tt_tmp, _tt_string_types):" 
+                          " _tt_tmp = _tt_utf8(_tt_tmp)", self.line) 
+        writer.write_line("else: _tt_tmp = _tt_utf8(str(_tt_tmp))", self.line) 
+        if not self.raw and writer.current_template.autoescape is not None: 
+            # In python3 functions like xhtml_escape return unicode, 
+            # so we have to convert to utf8 again. 
+            writer.write_line("_tt_tmp = _tt_utf8(%s(_tt_tmp))" % 
+                              writer.current_template.autoescape, self.line) 
+        writer.write_line("_tt_append(_tt_tmp)", self.line) 
+ 
+ 
+class _Module(_Expression): 
+    def __init__(self, expression, line): 
+        super(_Module, self).__init__("_tt_modules." + expression, line, 
+                                      raw=True) 
+ 
+ 
+class _Text(_Node): 
+    def __init__(self, value, line, whitespace): 
+        self.value = value 
+        self.line = line 
+        self.whitespace = whitespace 
+ 
+    def generate(self, writer): 
+        value = self.value 
+ 
+        # Compress whitespace if requested, with a crude heuristic to avoid 
+        # altering preformatted whitespace. 
+        if "<pre>" not in value: 
+            value = filter_whitespace(self.whitespace, value) 
+ 
+        if value: 
+            writer.write_line('_tt_append(%r)' % escape.utf8(value), self.line) 
+ 
+ 
+class ParseError(Exception): 
+    """Raised for template syntax errors. 
+ 
+    ``ParseError`` instances have ``filename`` and ``lineno`` attributes 
+    indicating the position of the error. 
+ 
+    .. versionchanged:: 4.3 
+       Added ``filename`` and ``lineno`` attributes. 
+    """ 
+    def __init__(self, message, filename=None, lineno=0): 
+        self.message = message 
+        # The names "filename" and "lineno" are chosen for consistency 
+        # with python SyntaxError. 
+        self.filename = filename 
+        self.lineno = lineno 
+ 
+    def __str__(self): 
+        return '%s at %s:%d' % (self.message, self.filename, self.lineno) 
+ 
+ 
+class _CodeWriter(object): 
+    def __init__(self, file, named_blocks, loader, current_template): 
+        self.file = file 
+        self.named_blocks = named_blocks 
+        self.loader = loader 
+        self.current_template = current_template 
+        self.apply_counter = 0 
+        self.include_stack = [] 
+        self._indent = 0 
+ 
+    def indent_size(self): 
+        return self._indent 
+ 
+    def indent(self): 
+        class Indenter(object): 
+            def __enter__(_): 
+                self._indent += 1 
+                return self 
+ 
+            def __exit__(_, *args): 
+                assert self._indent > 0 
+                self._indent -= 1 
+ 
+        return Indenter() 
+ 
+    def include(self, template, line): 
+        self.include_stack.append((self.current_template, line)) 
+        self.current_template = template 
+ 
+        class IncludeTemplate(object): 
+            def __enter__(_): 
+                return self 
+ 
+            def __exit__(_, *args): 
+                self.current_template = self.include_stack.pop()[0] 
+ 
+        return IncludeTemplate() 
+ 
+    def write_line(self, line, line_number, indent=None): 
+        if indent is None: 
+            indent = self._indent 
+        line_comment = '  # %s:%d' % (self.current_template.name, line_number) 
+        if self.include_stack: 
+            ancestors = ["%s:%d" % (tmpl.name, lineno) 
+                         for (tmpl, lineno) in self.include_stack] 
+            line_comment += ' (via %s)' % ', '.join(reversed(ancestors)) 
+        print("    " * indent + line + line_comment, file=self.file) 
+ 
+ 
+class _TemplateReader(object): 
+    def __init__(self, name, text, whitespace): 
+        self.name = name 
+        self.text = text 
+        self.whitespace = whitespace 
+        self.line = 1 
+        self.pos = 0 
+ 
+    def find(self, needle, start=0, end=None): 
+        assert start >= 0, start 
+        pos = self.pos 
+        start += pos 
+        if end is None: 
+            index = self.text.find(needle, start) 
+        else: 
+            end += pos 
+            assert end >= start 
+            index = self.text.find(needle, start, end) 
+        if index != -1: 
+            index -= pos 
+        return index 
+ 
+    def consume(self, count=None): 
+        if count is None: 
+            count = len(self.text) - self.pos 
+        newpos = self.pos + count 
+        self.line += self.text.count("\n", self.pos, newpos) 
+        s = self.text[self.pos:newpos] 
+        self.pos = newpos 
+        return s 
+ 
+    def remaining(self): 
+        return len(self.text) - self.pos 
+ 
+    def __len__(self): 
+        return self.remaining() 
+ 
+    def __getitem__(self, key): 
+        if type(key) is slice: 
+            size = len(self) 
+            start, stop, step = key.indices(size) 
+            if start is None: 
+                start = self.pos 
+            else: 
+                start += self.pos 
+            if stop is not None: 
+                stop += self.pos 
+            return self.text[slice(start, stop, step)] 
+        elif key < 0: 
+            return self.text[key] 
+        else: 
+            return self.text[self.pos + key] 
+ 
+    def __str__(self): 
+        return self.text[self.pos:] 
+ 
+    def raise_parse_error(self, msg): 
+        raise ParseError(msg, self.name, self.line) 
+ 
+ 
+def _format_code(code): 
+    lines = code.splitlines() 
+    format = "%%%dd  %%s\n" % len(repr(len(lines) + 1)) 
+    return "".join([format % (i + 1, line) for (i, line) in enumerate(lines)]) 
+ 
+ 
+def _parse(reader, template, in_block=None, in_loop=None): 
+    body = _ChunkList([]) 
+    while True: 
+        # Find next template directive 
+        curly = 0 
+        while True: 
+            curly = reader.find("{", curly) 
+            if curly == -1 or curly + 1 == reader.remaining(): 
+                # EOF 
+                if in_block: 
+                    reader.raise_parse_error( 
+                        "Missing {%% end %%} block for %s" % in_block) 
+                body.chunks.append(_Text(reader.consume(), reader.line, 
+                                         reader.whitespace)) 
+                return body 
+            # If the first curly brace is not the start of a special token, 
+            # start searching from the character after it 
+            if reader[curly + 1] not in ("{", "%", "#"): 
+                curly += 1 
+                continue 
+            # When there are more than 2 curlies in a row, use the 
+            # innermost ones.  This is useful when generating languages 
+            # like latex where curlies are also meaningful 
+            if (curly + 2 < reader.remaining() and 
+                    reader[curly + 1] == '{' and reader[curly + 2] == '{'): 
+                curly += 1 
+                continue 
+            break 
+ 
+        # Append any text before the special token 
+        if curly > 0: 
+            cons = reader.consume(curly) 
+            body.chunks.append(_Text(cons, reader.line, 
+                                     reader.whitespace)) 
+ 
+        start_brace = reader.consume(2) 
+        line = reader.line 
+ 
+        # Template directives may be escaped as "{{!" or "{%!". 
+        # In this case output the braces and consume the "!". 
+        # This is especially useful in conjunction with jquery templates, 
+        # which also use double braces. 
+        if reader.remaining() and reader[0] == "!": 
+            reader.consume(1) 
+            body.chunks.append(_Text(start_brace, line, 
+                                     reader.whitespace)) 
+            continue 
+ 
+        # Comment 
+        if start_brace == "{#": 
+            end = reader.find("#}") 
+            if end == -1: 
+                reader.raise_parse_error("Missing end comment #}") 
+            contents = reader.consume(end).strip() 
+            reader.consume(2) 
+            continue 
+ 
+        # Expression 
+        if start_brace == "{{": 
+            end = reader.find("}}") 
+            if end == -1: 
+                reader.raise_parse_error("Missing end expression }}") 
+            contents = reader.consume(end).strip() 
+            reader.consume(2) 
+            if not contents: 
+                reader.raise_parse_error("Empty expression") 
+            body.chunks.append(_Expression(contents, line)) 
+            continue 
+ 
+        # Block 
+        assert start_brace == "{%", start_brace 
+        end = reader.find("%}") 
+        if end == -1: 
+            reader.raise_parse_error("Missing end block %}") 
+        contents = reader.consume(end).strip() 
+        reader.consume(2) 
+        if not contents: 
+            reader.raise_parse_error("Empty block tag ({% %})") 
+ 
+        operator, space, suffix = contents.partition(" ") 
+        suffix = suffix.strip() 
+ 
+        # Intermediate ("else", "elif", etc) blocks 
+        intermediate_blocks = { 
+            "else": set(["if", "for", "while", "try"]), 
+            "elif": set(["if"]), 
+            "except": set(["try"]), 
+            "finally": set(["try"]), 
+        } 
+        allowed_parents = intermediate_blocks.get(operator) 
+        if allowed_parents is not None: 
+            if not in_block: 
+                reader.raise_parse_error("%s outside %s block" % 
+                                         (operator, allowed_parents)) 
+            if in_block not in allowed_parents: 
+                reader.raise_parse_error( 
+                    "%s block cannot be attached to %s block" % 
+                    (operator, in_block)) 
+            body.chunks.append(_IntermediateControlBlock(contents, line)) 
+            continue 
+ 
+        # End tag 
+        elif operator == "end": 
+            if not in_block: 
+                reader.raise_parse_error("Extra {% end %} block") 
+            return body 
+ 
+        elif operator in ("extends", "include", "set", "import", "from", 
+                          "comment", "autoescape", "whitespace", "raw", 
+                          "module"): 
+            if operator == "comment": 
+                continue 
+            if operator == "extends": 
+                suffix = suffix.strip('"').strip("'") 
+                if not suffix: 
+                    reader.raise_parse_error("extends missing file path") 
+                block = _ExtendsBlock(suffix) 
+            elif operator in ("import", "from"): 
+                if not suffix: 
+                    reader.raise_parse_error("import missing statement") 
+                block = _Statement(contents, line) 
+            elif operator == "include": 
+                suffix = suffix.strip('"').strip("'") 
+                if not suffix: 
+                    reader.raise_parse_error("include missing file path") 
+                block = _IncludeBlock(suffix, reader, line) 
+            elif operator == "set": 
+                if not suffix: 
+                    reader.raise_parse_error("set missing statement") 
+                block = _Statement(suffix, line) 
+            elif operator == "autoescape": 
+                fn = suffix.strip() 
+                if fn == "None": 
+                    fn = None 
+                template.autoescape = fn 
+                continue 
+            elif operator == "whitespace": 
+                mode = suffix.strip() 
+                # Validate the selected mode 
+                filter_whitespace(mode, '') 
+                reader.whitespace = mode 
+                continue 
+            elif operator == "raw": 
+                block = _Expression(suffix, line, raw=True) 
+            elif operator == "module": 
+                block = _Module(suffix, line) 
+            body.chunks.append(block) 
+            continue 
+ 
+        elif operator in ("apply", "block", "try", "if", "for", "while"): 
+            # parse inner body recursively 
+            if operator in ("for", "while"): 
+                block_body = _parse(reader, template, operator, operator) 
+            elif operator == "apply": 
+                # apply creates a nested function so syntactically it's not 
+                # in the loop. 
+                block_body = _parse(reader, template, operator, None) 
+            else: 
+                block_body = _parse(reader, template, operator, in_loop) 
+ 
+            if operator == "apply": 
+                if not suffix: 
+                    reader.raise_parse_error("apply missing method name") 
+                block = _ApplyBlock(suffix, line, block_body) 
+            elif operator == "block": 
+                if not suffix: 
+                    reader.raise_parse_error("block missing name") 
+                block = _NamedBlock(suffix, block_body, template, line) 
+            else: 
+                block = _ControlBlock(contents, line, block_body) 
+            body.chunks.append(block) 
+            continue 
+ 
+        elif operator in ("break", "continue"): 
+            if not in_loop: 
+                reader.raise_parse_error("%s outside %s block" % 
+                                         (operator, set(["for", "while"]))) 
+            body.chunks.append(_Statement(contents, line)) 
+            continue 
+ 
+        else: 
+            reader.raise_parse_error("unknown operator: %r" % operator) 
diff --git a/contrib/python/tornado/tornado-4/tornado/testing.py b/contrib/python/tornado/tornado-4/tornado/testing.py
index 82a3b93732..762d3133a0 100644
--- a/contrib/python/tornado/tornado-4/tornado/testing.py
+++ b/contrib/python/tornado/tornado-4/tornado/testing.py
@@ -1,742 +1,742 @@
-#!/usr/bin/env python
-"""Support classes for automated testing.
-
-* `AsyncTestCase` and `AsyncHTTPTestCase`:  Subclasses of unittest.TestCase
-  with additional support for testing asynchronous (`.IOLoop`-based) code.
-
-* `ExpectLog` and `LogTrapTestCase`: Make test logs less spammy.
-
-* `main()`: A simple test runner (wrapper around unittest.main()) with support
-  for the tornado.autoreload module to rerun the tests when code changes.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-try:
-    from tornado import gen
-    from tornado.httpclient import AsyncHTTPClient
-    from tornado.httpserver import HTTPServer
-    from tornado.simple_httpclient import SimpleAsyncHTTPClient
-    from tornado.ioloop import IOLoop, TimeoutError
-    from tornado import netutil
-    from tornado.process import Subprocess
-except ImportError:
-    # These modules are not importable on app engine.  Parts of this module
-    # won't work, but e.g. LogTrapTestCase and main() will.
-    AsyncHTTPClient = None  # type: ignore
-    gen = None  # type: ignore
-    HTTPServer = None  # type: ignore
-    IOLoop = None  # type: ignore
-    netutil = None  # type: ignore
-    SimpleAsyncHTTPClient = None  # type: ignore
-    Subprocess = None  # type: ignore
-from tornado.log import gen_log, app_log
-from tornado.stack_context import ExceptionStackContext
-from tornado.util import raise_exc_info, basestring_type, PY3
-import functools
-import inspect
-import logging
-import os
-import re
-import signal
-import socket
-import sys
-
-if PY3:
-    from io import StringIO
-else:
-    from cStringIO import StringIO
-
-try:
-    from collections.abc import Generator as GeneratorType  # type: ignore
-except ImportError:
-    from types import GeneratorType  # type: ignore
-
-if sys.version_info >= (3, 5):
-    iscoroutine = inspect.iscoroutine  # type: ignore
-    iscoroutinefunction = inspect.iscoroutinefunction  # type: ignore
-else:
-    iscoroutine = iscoroutinefunction = lambda f: False
-
-# Tornado's own test suite requires the updated unittest module
-# (either py27+ or unittest2) so tornado.test.util enforces
-# this requirement, but for other users of tornado.testing we want
-# to allow the older version if unitest2 is not available.
-if PY3:
-    # On python 3, mixing unittest2 and unittest (including doctest)
-    # doesn't seem to work, so always use unittest.
-    import unittest
-else:
-    # On python 2, prefer unittest2 when available.
-    try:
-        import unittest2 as unittest  # type: ignore
-    except ImportError:
-        import unittest  # type: ignore
-
-_next_port = 10000
-
-
-def get_unused_port():
-    """Returns a (hopefully) unused port number.
-
-    This function does not guarantee that the port it returns is available,
-    only that a series of get_unused_port calls in a single process return
-    distinct ports.
-
-    .. deprecated::
-       Use bind_unused_port instead, which is guaranteed to find an unused port.
-    """
-    global _next_port
-    port = _next_port
-    _next_port = _next_port + 1
-    return port
-
-
-def bind_unused_port(reuse_port=False):
-    """Binds a server socket to an available port on localhost.
-
-    Returns a tuple (socket, port).
-
-    .. versionchanged:: 4.4
-       Always binds to ``127.0.0.1`` without resolving the name
-       ``localhost``.
-    """
-    sock = netutil.bind_sockets(None, '127.0.0.1', family=socket.AF_INET,
-                                reuse_port=reuse_port)[0]
-    port = sock.getsockname()[1]
-    return sock, port
-
-
-def get_async_test_timeout():
-    """Get the global timeout setting for async tests.
-
-    Returns a float, the timeout in seconds.
-
-    .. versionadded:: 3.1
-    """
-    try:
-        return float(os.environ.get('ASYNC_TEST_TIMEOUT'))
-    except (ValueError, TypeError):
-        return 5
-
-
-class _TestMethodWrapper(object):
-    """Wraps a test method to raise an error if it returns a value.
-
-    This is mainly used to detect undecorated generators (if a test
-    method yields it must use a decorator to consume the generator),
-    but will also detect other kinds of return values (these are not
-    necessarily errors, but we alert anyway since there is no good
-    reason to return a value from a test).
-    """
-    def __init__(self, orig_method):
-        self.orig_method = orig_method
-
-    def __call__(self, *args, **kwargs):
-        result = self.orig_method(*args, **kwargs)
-        if isinstance(result, GeneratorType) or iscoroutine(result):
-            raise TypeError("Generator and coroutine test methods should be"
-                            " decorated with tornado.testing.gen_test")
-        elif result is not None:
-            raise ValueError("Return value from test method ignored: %r" %
-                             result)
-
-    def __getattr__(self, name):
-        """Proxy all unknown attributes to the original method.
-
-        This is important for some of the decorators in the `unittest`
-        module, such as `unittest.skipIf`.
-        """
-        return getattr(self.orig_method, name)
-
-
-class AsyncTestCase(unittest.TestCase):
-    """`~unittest.TestCase` subclass for testing `.IOLoop`-based
-    asynchronous code.
-
-    The unittest framework is synchronous, so the test must be
-    complete by the time the test method returns.  This means that
-    asynchronous code cannot be used in quite the same way as usual.
-    To write test functions that use the same ``yield``-based patterns
-    used with the `tornado.gen` module, decorate your test methods
-    with `tornado.testing.gen_test` instead of
-    `tornado.gen.coroutine`.  This class also provides the `stop()`
-    and `wait()` methods for a more manual style of testing.  The test
-    method itself must call ``self.wait()``, and asynchronous
-    callbacks should call ``self.stop()`` to signal completion.
-
-    By default, a new `.IOLoop` is constructed for each test and is available
-    as ``self.io_loop``.  This `.IOLoop` should be used in the construction of
-    HTTP clients/servers, etc.  If the code being tested requires a
-    global `.IOLoop`, subclasses should override `get_new_ioloop` to return it.
-
-    The `.IOLoop`'s ``start`` and ``stop`` methods should not be
-    called directly.  Instead, use `self.stop <stop>` and `self.wait
-    <wait>`.  Arguments passed to ``self.stop`` are returned from
-    ``self.wait``.  It is possible to have multiple ``wait``/``stop``
-    cycles in the same test.
-
-    Example::
-
-        # This test uses coroutine style.
-        class MyTestCase(AsyncTestCase):
-            @tornado.testing.gen_test
-            def test_http_fetch(self):
-                client = AsyncHTTPClient(self.io_loop)
-                response = yield client.fetch("http://www.tornadoweb.org")
-                # Test contents of response
-                self.assertIn("FriendFeed", response.body)
-
-        # This test uses argument passing between self.stop and self.wait.
-        class MyTestCase2(AsyncTestCase):
-            def test_http_fetch(self):
-                client = AsyncHTTPClient(self.io_loop)
-                client.fetch("http://www.tornadoweb.org/", self.stop)
-                response = self.wait()
-                # Test contents of response
-                self.assertIn("FriendFeed", response.body)
-
-        # This test uses an explicit callback-based style.
-        class MyTestCase3(AsyncTestCase):
-            def test_http_fetch(self):
-                client = AsyncHTTPClient(self.io_loop)
-                client.fetch("http://www.tornadoweb.org/", self.handle_fetch)
-                self.wait()
-
-            def handle_fetch(self, response):
-                # Test contents of response (failures and exceptions here
-                # will cause self.wait() to throw an exception and end the
-                # test).
-                # Exceptions thrown here are magically propagated to
-                # self.wait() in test_http_fetch() via stack_context.
-                self.assertIn("FriendFeed", response.body)
-                self.stop()
-    """
-    def __init__(self, methodName='runTest'):
-        super(AsyncTestCase, self).__init__(methodName)
-        self.__stopped = False
-        self.__running = False
-        self.__failure = None
-        self.__stop_args = None
-        self.__timeout = None
-
-        # It's easy to forget the @gen_test decorator, but if you do
-        # the test will silently be ignored because nothing will consume
-        # the generator.  Replace the test method with a wrapper that will
-        # make sure it's not an undecorated generator.
-        setattr(self, methodName, _TestMethodWrapper(getattr(self, methodName)))
-
-    def setUp(self):
-        super(AsyncTestCase, self).setUp()
-        self.io_loop = self.get_new_ioloop()
-        self.io_loop.make_current()
-
-    def tearDown(self):
-        # Clean up Subprocess, so it can be used again with a new ioloop.
-        Subprocess.uninitialize()
-        self.io_loop.clear_current()
-        if (not IOLoop.initialized() or
-                self.io_loop is not IOLoop.instance()):
-            # Try to clean up any file descriptors left open in the ioloop.
-            # This avoids leaks, especially when tests are run repeatedly
-            # in the same process with autoreload (because curl does not
-            # set FD_CLOEXEC on its file descriptors)
-            self.io_loop.close(all_fds=True)
-        super(AsyncTestCase, self).tearDown()
-        # In case an exception escaped or the StackContext caught an exception
-        # when there wasn't a wait() to re-raise it, do so here.
-        # This is our last chance to raise an exception in a way that the
-        # unittest machinery understands.
-        self.__rethrow()
-
-    def get_new_ioloop(self):
-        """Creates a new `.IOLoop` for this test.  May be overridden in
-        subclasses for tests that require a specific `.IOLoop` (usually
-        the singleton `.IOLoop.instance()`).
-        """
-        return IOLoop()
-
-    def _handle_exception(self, typ, value, tb):
-        if self.__failure is None:
-            self.__failure = (typ, value, tb)
-        else:
-            app_log.error("multiple unhandled exceptions in test",
-                          exc_info=(typ, value, tb))
-        self.stop()
-        return True
-
-    def __rethrow(self):
-        if self.__failure is not None:
-            failure = self.__failure
-            self.__failure = None
-            raise_exc_info(failure)
-
-    def run(self, result=None):
-        with ExceptionStackContext(self._handle_exception):
-            super(AsyncTestCase, self).run(result)
-        # As a last resort, if an exception escaped super.run() and wasn't
-        # re-raised in tearDown, raise it here.  This will cause the
-        # unittest run to fail messily, but that's better than silently
-        # ignoring an error.
-        self.__rethrow()
-
-    def stop(self, _arg=None, **kwargs):
-        """Stops the `.IOLoop`, causing one pending (or future) call to `wait()`
-        to return.
-
-        Keyword arguments or a single positional argument passed to `stop()` are
-        saved and will be returned by `wait()`.
-        """
-        assert _arg is None or not kwargs
-        self.__stop_args = kwargs or _arg
-        if self.__running:
-            self.io_loop.stop()
-            self.__running = False
-        self.__stopped = True
-
-    def wait(self, condition=None, timeout=None):
-        """Runs the `.IOLoop` until stop is called or timeout has passed.
-
-        In the event of a timeout, an exception will be thrown. The
-        default timeout is 5 seconds; it may be overridden with a
-        ``timeout`` keyword argument or globally with the
-        ``ASYNC_TEST_TIMEOUT`` environment variable.
-
-        If ``condition`` is not None, the `.IOLoop` will be restarted
-        after `stop()` until ``condition()`` returns true.
-
-        .. versionchanged:: 3.1
-           Added the ``ASYNC_TEST_TIMEOUT`` environment variable.
-        """
-        if timeout is None:
-            timeout = get_async_test_timeout()
-
-        if not self.__stopped:
-            if timeout:
-                def timeout_func():
-                    try:
-                        raise self.failureException(
-                            'Async operation timed out after %s seconds' %
-                            timeout)
-                    except Exception:
-                        self.__failure = sys.exc_info()
-                    self.stop()
-                self.__timeout = self.io_loop.add_timeout(self.io_loop.time() + timeout, timeout_func)
-            while True:
-                self.__running = True
-                self.io_loop.start()
-                if (self.__failure is not None or
-                        condition is None or condition()):
-                    break
-            if self.__timeout is not None:
-                self.io_loop.remove_timeout(self.__timeout)
-                self.__timeout = None
-        assert self.__stopped
-        self.__stopped = False
-        self.__rethrow()
-        result = self.__stop_args
-        self.__stop_args = None
-        return result
-
-
-class AsyncHTTPTestCase(AsyncTestCase):
-    """A test case that starts up an HTTP server.
-
-    Subclasses must override `get_app()`, which returns the
-    `tornado.web.Application` (or other `.HTTPServer` callback) to be tested.
-    Tests will typically use the provided ``self.http_client`` to fetch
-    URLs from this server.
-
-    Example, assuming the "Hello, world" example from the user guide is in
-    ``hello.py``::
-
-        import hello
-
-        class TestHelloApp(AsyncHTTPTestCase):
-            def get_app(self):
-                return hello.make_app()
-
-            def test_homepage(self):
-                response = self.fetch('/')
-                self.assertEqual(response.code, 200)
-                self.assertEqual(response.body, 'Hello, world')
-
-    That call to ``self.fetch()`` is equivalent to ::
-
-        self.http_client.fetch(self.get_url('/'), self.stop)
-        response = self.wait()
-
-    which illustrates how AsyncTestCase can turn an asynchronous operation,
-    like ``http_client.fetch()``, into a synchronous operation. If you need
-    to do other asynchronous operations in tests, you'll probably need to use
-    ``stop()`` and ``wait()`` yourself.
-    """
-    def setUp(self):
-        super(AsyncHTTPTestCase, self).setUp()
-        sock, port = bind_unused_port()
-        self.__port = port
-
-        self.http_client = self.get_http_client()
-        self._app = self.get_app()
-        self.http_server = self.get_http_server()
-        self.http_server.add_sockets([sock])
-
-    def get_http_client(self):
-        return AsyncHTTPClient(io_loop=self.io_loop)
-
-    def get_http_server(self):
-        return HTTPServer(self._app, io_loop=self.io_loop,
-                          **self.get_httpserver_options())
-
-    def get_app(self):
-        """Should be overridden by subclasses to return a
-        `tornado.web.Application` or other `.HTTPServer` callback.
-        """
-        raise NotImplementedError()
-
-    def fetch(self, path, **kwargs):
-        """Convenience method to synchronously fetch a url.
-
-        The given path will be appended to the local server's host and
-        port.  Any additional kwargs will be passed directly to
-        `.AsyncHTTPClient.fetch` (and so could be used to pass
-        ``method="POST"``, ``body="..."``, etc).
-        """
-        self.http_client.fetch(self.get_url(path), self.stop, **kwargs)
-        return self.wait()
-
-    def get_httpserver_options(self):
-        """May be overridden by subclasses to return additional
-        keyword arguments for the server.
-        """
-        return {}
-
-    def get_http_port(self):
-        """Returns the port used by the server.
-
-        A new port is chosen for each test.
-        """
-        return self.__port
-
-    def get_protocol(self):
-        return 'http'
-
-    def get_url(self, path):
-        """Returns an absolute url for the given path on the test server."""
-        return '%s://127.0.0.1:%s%s' % (self.get_protocol(),
-                                        self.get_http_port(), path)
-
-    def tearDown(self):
-        self.http_server.stop()
-        self.io_loop.run_sync(self.http_server.close_all_connections,
-                              timeout=get_async_test_timeout())
-        if (not IOLoop.initialized() or
-                self.http_client.io_loop is not IOLoop.instance()):
-            self.http_client.close()
-        super(AsyncHTTPTestCase, self).tearDown()
-
-
-class AsyncHTTPSTestCase(AsyncHTTPTestCase):
-    """A test case that starts an HTTPS server.
-
-    Interface is generally the same as `AsyncHTTPTestCase`.
-    """
-    def get_http_client(self):
-        return AsyncHTTPClient(io_loop=self.io_loop, force_instance=True,
-                               defaults=dict(validate_cert=False))
-
-    def get_httpserver_options(self):
-        return dict(ssl_options=self.get_ssl_options())
-
-    def get_ssl_options(self):
-        """May be overridden by subclasses to select SSL options.
-
-        By default includes a self-signed testing certificate.
-        """
-        # Testing keys were generated with:
-        # openssl req -new -keyout tornado/test/test.key -out tornado/test/test.crt -nodes -days 3650 -x509
-        module_dir = os.path.dirname(__file__)
-        return dict(
-            certfile=os.path.join(module_dir, 'test', 'test.crt'),
-            keyfile=os.path.join(module_dir, 'test', 'test.key'))
-
-    def get_protocol(self):
-        return 'https'
-
-
-def gen_test(func=None, timeout=None):
-    """Testing equivalent of ``@gen.coroutine``, to be applied to test methods.
-
-    ``@gen.coroutine`` cannot be used on tests because the `.IOLoop` is not
-    already running.  ``@gen_test`` should be applied to test methods
-    on subclasses of `AsyncTestCase`.
-
-    Example::
-
-        class MyTest(AsyncHTTPTestCase):
-            @gen_test
-            def test_something(self):
-                response = yield gen.Task(self.fetch('/'))
-
-    By default, ``@gen_test`` times out after 5 seconds. The timeout may be
-    overridden globally with the ``ASYNC_TEST_TIMEOUT`` environment variable,
-    or for each test with the ``timeout`` keyword argument::
-
-        class MyTest(AsyncHTTPTestCase):
-            @gen_test(timeout=10)
-            def test_something_slow(self):
-                response = yield gen.Task(self.fetch('/'))
-
-    .. versionadded:: 3.1
-       The ``timeout`` argument and ``ASYNC_TEST_TIMEOUT`` environment
-       variable.
-
-    .. versionchanged:: 4.0
-       The wrapper now passes along ``*args, **kwargs`` so it can be used
-       on functions with arguments.
-    """
-    if timeout is None:
-        timeout = get_async_test_timeout()
-
-    def wrap(f):
-        # Stack up several decorators to allow us to access the generator
-        # object itself.  In the innermost wrapper, we capture the generator
-        # and save it in an attribute of self.  Next, we run the wrapped
-        # function through @gen.coroutine.  Finally, the coroutine is
-        # wrapped again to make it synchronous with run_sync.
-        #
-        # This is a good case study arguing for either some sort of
-        # extensibility in the gen decorators or cancellation support.
-        @functools.wraps(f)
-        def pre_coroutine(self, *args, **kwargs):
-            result = f(self, *args, **kwargs)
-            if isinstance(result, GeneratorType) or iscoroutine(result):
-                self._test_generator = result
-            else:
-                self._test_generator = None
-            return result
-
-        if iscoroutinefunction(f):
-            coro = pre_coroutine
-        else:
-            coro = gen.coroutine(pre_coroutine)
-
-        @functools.wraps(coro)
-        def post_coroutine(self, *args, **kwargs):
-            try:
-                return self.io_loop.run_sync(
-                    functools.partial(coro, self, *args, **kwargs),
-                    timeout=timeout)
-            except TimeoutError as e:
-                # run_sync raises an error with an unhelpful traceback.
-                # Throw it back into the generator or coroutine so the stack
-                # trace is replaced by the point where the test is stopped.
-                self._test_generator.throw(e)
-                # In case the test contains an overly broad except clause,
-                # we may get back here.  In this case re-raise the original
-                # exception, which is better than nothing.
-                raise
-        return post_coroutine
-
-    if func is not None:
-        # Used like:
-        #     @gen_test
-        #     def f(self):
-        #         pass
-        return wrap(func)
-    else:
-        # Used like @gen_test(timeout=10)
-        return wrap
-
-
-# Without this attribute, nosetests will try to run gen_test as a test
-# anywhere it is imported.
-gen_test.__test__ = False  # type: ignore
-
-
-class LogTrapTestCase(unittest.TestCase):
-    """A test case that captures and discards all logging output
-    if the test passes.
-
-    Some libraries can produce a lot of logging output even when
-    the test succeeds, so this class can be useful to minimize the noise.
-    Simply use it as a base class for your test case.  It is safe to combine
-    with AsyncTestCase via multiple inheritance
-    (``class MyTestCase(AsyncHTTPTestCase, LogTrapTestCase):``)
-
-    This class assumes that only one log handler is configured and
-    that it is a `~logging.StreamHandler`.  This is true for both
-    `logging.basicConfig` and the "pretty logging" configured by
-    `tornado.options`.  It is not compatible with other log buffering
-    mechanisms, such as those provided by some test runners.
-
-    .. deprecated:: 4.1
-       Use the unittest module's ``--buffer`` option instead, or `.ExpectLog`.
-    """
-    def run(self, result=None):
-        logger = logging.getLogger()
-        if not logger.handlers:
-            logging.basicConfig()
-        handler = logger.handlers[0]
-        if (len(logger.handlers) > 1 or
-                not isinstance(handler, logging.StreamHandler)):
-            # Logging has been configured in a way we don't recognize,
-            # so just leave it alone.
-            super(LogTrapTestCase, self).run(result)
-            return
-        old_stream = handler.stream
-        try:
-            handler.stream = StringIO()
-            gen_log.info("RUNNING TEST: " + str(self))
-            old_error_count = len(result.failures) + len(result.errors)
-            super(LogTrapTestCase, self).run(result)
-            new_error_count = len(result.failures) + len(result.errors)
-            if new_error_count != old_error_count:
-                old_stream.write(handler.stream.getvalue())
-        finally:
-            handler.stream = old_stream
-
-
-class ExpectLog(logging.Filter):
-    """Context manager to capture and suppress expected log output.
-
-    Useful to make tests of error conditions less noisy, while still
-    leaving unexpected log entries visible.  *Not thread safe.*
-
-    The attribute ``logged_stack`` is set to true if any exception
-    stack trace was logged.
-
-    Usage::
-
-        with ExpectLog('tornado.application', "Uncaught exception"):
-            error_response = self.fetch("/some_page")
-
-    .. versionchanged:: 4.3
-       Added the ``logged_stack`` attribute.
-    """
-    def __init__(self, logger, regex, required=True):
-        """Constructs an ExpectLog context manager.
-
-        :param logger: Logger object (or name of logger) to watch.  Pass
-            an empty string to watch the root logger.
-        :param regex: Regular expression to match.  Any log entries on
-            the specified logger that match this regex will be suppressed.
-        :param required: If true, an exception will be raised if the end of
-            the ``with`` statement is reached without matching any log entries.
-        """
-        if isinstance(logger, basestring_type):
-            logger = logging.getLogger(logger)
-        self.logger = logger
-        self.regex = re.compile(regex)
-        self.required = required
-        self.matched = False
-        self.logged_stack = False
-
-    def filter(self, record):
-        if record.exc_info:
-            self.logged_stack = True
-        message = record.getMessage()
-        if self.regex.match(message):
-            self.matched = True
-            return False
-        return True
-
-    def __enter__(self):
-        self.logger.addFilter(self)
-        return self
-
-    def __exit__(self, typ, value, tb):
-        self.logger.removeFilter(self)
-        if not typ and self.required and not self.matched:
-            raise Exception("did not get expected log message")
-
-
-def main(**kwargs):
-    """A simple test runner.
-
-    This test runner is essentially equivalent to `unittest.main` from
-    the standard library, but adds support for tornado-style option
-    parsing and log formatting. It is *not* necessary to use this
-    `main` function to run tests using `AsyncTestCase`; these tests
-    are self-contained and can run with any test runner.
-
-    The easiest way to run a test is via the command line::
-
-        python -m tornado.testing tornado.test.stack_context_test
-
-    See the standard library unittest module for ways in which tests can
-    be specified.
-
-    Projects with many tests may wish to define a test script like
-    ``tornado/test/runtests.py``.  This script should define a method
-    ``all()`` which returns a test suite and then call
-    `tornado.testing.main()`.  Note that even when a test script is
-    used, the ``all()`` test suite may be overridden by naming a
-    single test on the command line::
-
-        # Runs all tests
-        python -m tornado.test.runtests
-        # Runs one test
-        python -m tornado.test.runtests tornado.test.stack_context_test
-
-    Additional keyword arguments passed through to ``unittest.main()``.
-    For example, use ``tornado.testing.main(verbosity=2)``
-    to show many test details as they are run.
+#!/usr/bin/env python 
+"""Support classes for automated testing. 
+ 
+* `AsyncTestCase` and `AsyncHTTPTestCase`:  Subclasses of unittest.TestCase 
+  with additional support for testing asynchronous (`.IOLoop`-based) code. 
+ 
+* `ExpectLog` and `LogTrapTestCase`: Make test logs less spammy. 
+ 
+* `main()`: A simple test runner (wrapper around unittest.main()) with support 
+  for the tornado.autoreload module to rerun the tests when code changes. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+try: 
+    from tornado import gen 
+    from tornado.httpclient import AsyncHTTPClient 
+    from tornado.httpserver import HTTPServer 
+    from tornado.simple_httpclient import SimpleAsyncHTTPClient 
+    from tornado.ioloop import IOLoop, TimeoutError 
+    from tornado import netutil 
+    from tornado.process import Subprocess 
+except ImportError: 
+    # These modules are not importable on app engine.  Parts of this module 
+    # won't work, but e.g. LogTrapTestCase and main() will. 
+    AsyncHTTPClient = None  # type: ignore 
+    gen = None  # type: ignore 
+    HTTPServer = None  # type: ignore 
+    IOLoop = None  # type: ignore 
+    netutil = None  # type: ignore 
+    SimpleAsyncHTTPClient = None  # type: ignore 
+    Subprocess = None  # type: ignore 
+from tornado.log import gen_log, app_log 
+from tornado.stack_context import ExceptionStackContext 
+from tornado.util import raise_exc_info, basestring_type, PY3 
+import functools 
+import inspect 
+import logging 
+import os 
+import re 
+import signal 
+import socket 
+import sys 
+ 
+if PY3: 
+    from io import StringIO 
+else: 
+    from cStringIO import StringIO 
+ 
+try: 
+    from collections.abc import Generator as GeneratorType  # type: ignore 
+except ImportError: 
+    from types import GeneratorType  # type: ignore 
+ 
+if sys.version_info >= (3, 5): 
+    iscoroutine = inspect.iscoroutine  # type: ignore 
+    iscoroutinefunction = inspect.iscoroutinefunction  # type: ignore 
+else: 
+    iscoroutine = iscoroutinefunction = lambda f: False 
+ 
+# Tornado's own test suite requires the updated unittest module 
+# (either py27+ or unittest2) so tornado.test.util enforces 
+# this requirement, but for other users of tornado.testing we want 
+# to allow the older version if unitest2 is not available. 
+if PY3: 
+    # On python 3, mixing unittest2 and unittest (including doctest) 
+    # doesn't seem to work, so always use unittest. 
+    import unittest 
+else: 
+    # On python 2, prefer unittest2 when available. 
+    try: 
+        import unittest2 as unittest  # type: ignore 
+    except ImportError: 
+        import unittest  # type: ignore 
+ 
+_next_port = 10000 
+ 
+ 
+def get_unused_port(): 
+    """Returns a (hopefully) unused port number. 
+ 
+    This function does not guarantee that the port it returns is available, 
+    only that a series of get_unused_port calls in a single process return 
+    distinct ports. 
+ 
+    .. deprecated:: 
+       Use bind_unused_port instead, which is guaranteed to find an unused port. 
+    """ 
+    global _next_port 
+    port = _next_port 
+    _next_port = _next_port + 1 
+    return port 
+ 
+ 
+def bind_unused_port(reuse_port=False): 
+    """Binds a server socket to an available port on localhost. 
+ 
+    Returns a tuple (socket, port). 
+ 
+    .. versionchanged:: 4.4 
+       Always binds to ``127.0.0.1`` without resolving the name 
+       ``localhost``. 
+    """ 
+    sock = netutil.bind_sockets(None, '127.0.0.1', family=socket.AF_INET, 
+                                reuse_port=reuse_port)[0] 
+    port = sock.getsockname()[1] 
+    return sock, port 
+ 
+ 
+def get_async_test_timeout(): 
+    """Get the global timeout setting for async tests. 
+ 
+    Returns a float, the timeout in seconds. 
+ 
+    .. versionadded:: 3.1 
+    """ 
+    try: 
+        return float(os.environ.get('ASYNC_TEST_TIMEOUT')) 
+    except (ValueError, TypeError): 
+        return 5 
+ 
+ 
+class _TestMethodWrapper(object): 
+    """Wraps a test method to raise an error if it returns a value. 
+ 
+    This is mainly used to detect undecorated generators (if a test 
+    method yields it must use a decorator to consume the generator), 
+    but will also detect other kinds of return values (these are not 
+    necessarily errors, but we alert anyway since there is no good 
+    reason to return a value from a test). 
+    """ 
+    def __init__(self, orig_method): 
+        self.orig_method = orig_method 
+ 
+    def __call__(self, *args, **kwargs): 
+        result = self.orig_method(*args, **kwargs) 
+        if isinstance(result, GeneratorType) or iscoroutine(result): 
+            raise TypeError("Generator and coroutine test methods should be" 
+                            " decorated with tornado.testing.gen_test") 
+        elif result is not None: 
+            raise ValueError("Return value from test method ignored: %r" % 
+                             result) 
+ 
+    def __getattr__(self, name): 
+        """Proxy all unknown attributes to the original method. 
+ 
+        This is important for some of the decorators in the `unittest` 
+        module, such as `unittest.skipIf`. 
+        """ 
+        return getattr(self.orig_method, name) 
+ 
+ 
+class AsyncTestCase(unittest.TestCase): 
+    """`~unittest.TestCase` subclass for testing `.IOLoop`-based 
+    asynchronous code. 
+ 
+    The unittest framework is synchronous, so the test must be 
+    complete by the time the test method returns.  This means that 
+    asynchronous code cannot be used in quite the same way as usual. 
+    To write test functions that use the same ``yield``-based patterns 
+    used with the `tornado.gen` module, decorate your test methods 
+    with `tornado.testing.gen_test` instead of 
+    `tornado.gen.coroutine`.  This class also provides the `stop()` 
+    and `wait()` methods for a more manual style of testing.  The test 
+    method itself must call ``self.wait()``, and asynchronous 
+    callbacks should call ``self.stop()`` to signal completion. 
+ 
+    By default, a new `.IOLoop` is constructed for each test and is available 
+    as ``self.io_loop``.  This `.IOLoop` should be used in the construction of 
+    HTTP clients/servers, etc.  If the code being tested requires a 
+    global `.IOLoop`, subclasses should override `get_new_ioloop` to return it. 
+ 
+    The `.IOLoop`'s ``start`` and ``stop`` methods should not be 
+    called directly.  Instead, use `self.stop <stop>` and `self.wait 
+    <wait>`.  Arguments passed to ``self.stop`` are returned from 
+    ``self.wait``.  It is possible to have multiple ``wait``/``stop`` 
+    cycles in the same test. 
+ 
+    Example:: 
+ 
+        # This test uses coroutine style. 
+        class MyTestCase(AsyncTestCase): 
+            @tornado.testing.gen_test 
+            def test_http_fetch(self): 
+                client = AsyncHTTPClient(self.io_loop) 
+                response = yield client.fetch("http://www.tornadoweb.org") 
+                # Test contents of response 
+                self.assertIn("FriendFeed", response.body) 
+ 
+        # This test uses argument passing between self.stop and self.wait. 
+        class MyTestCase2(AsyncTestCase): 
+            def test_http_fetch(self): 
+                client = AsyncHTTPClient(self.io_loop) 
+                client.fetch("http://www.tornadoweb.org/", self.stop) 
+                response = self.wait() 
+                # Test contents of response 
+                self.assertIn("FriendFeed", response.body) 
+ 
+        # This test uses an explicit callback-based style. 
+        class MyTestCase3(AsyncTestCase): 
+            def test_http_fetch(self): 
+                client = AsyncHTTPClient(self.io_loop) 
+                client.fetch("http://www.tornadoweb.org/", self.handle_fetch) 
+                self.wait() 
+ 
+            def handle_fetch(self, response): 
+                # Test contents of response (failures and exceptions here 
+                # will cause self.wait() to throw an exception and end the 
+                # test). 
+                # Exceptions thrown here are magically propagated to 
+                # self.wait() in test_http_fetch() via stack_context. 
+                self.assertIn("FriendFeed", response.body) 
+                self.stop() 
+    """ 
+    def __init__(self, methodName='runTest'): 
+        super(AsyncTestCase, self).__init__(methodName) 
+        self.__stopped = False 
+        self.__running = False 
+        self.__failure = None 
+        self.__stop_args = None 
+        self.__timeout = None 
+ 
+        # It's easy to forget the @gen_test decorator, but if you do 
+        # the test will silently be ignored because nothing will consume 
+        # the generator.  Replace the test method with a wrapper that will 
+        # make sure it's not an undecorated generator. 
+        setattr(self, methodName, _TestMethodWrapper(getattr(self, methodName))) 
+ 
+    def setUp(self): 
+        super(AsyncTestCase, self).setUp() 
+        self.io_loop = self.get_new_ioloop() 
+        self.io_loop.make_current() 
+ 
+    def tearDown(self): 
+        # Clean up Subprocess, so it can be used again with a new ioloop. 
+        Subprocess.uninitialize() 
+        self.io_loop.clear_current() 
+        if (not IOLoop.initialized() or 
+                self.io_loop is not IOLoop.instance()): 
+            # Try to clean up any file descriptors left open in the ioloop. 
+            # This avoids leaks, especially when tests are run repeatedly 
+            # in the same process with autoreload (because curl does not 
+            # set FD_CLOEXEC on its file descriptors) 
+            self.io_loop.close(all_fds=True) 
+        super(AsyncTestCase, self).tearDown() 
+        # In case an exception escaped or the StackContext caught an exception 
+        # when there wasn't a wait() to re-raise it, do so here. 
+        # This is our last chance to raise an exception in a way that the 
+        # unittest machinery understands. 
+        self.__rethrow() 
+ 
+    def get_new_ioloop(self): 
+        """Creates a new `.IOLoop` for this test.  May be overridden in 
+        subclasses for tests that require a specific `.IOLoop` (usually 
+        the singleton `.IOLoop.instance()`). 
+        """ 
+        return IOLoop() 
+ 
+    def _handle_exception(self, typ, value, tb): 
+        if self.__failure is None: 
+            self.__failure = (typ, value, tb) 
+        else: 
+            app_log.error("multiple unhandled exceptions in test", 
+                          exc_info=(typ, value, tb)) 
+        self.stop() 
+        return True 
+ 
+    def __rethrow(self): 
+        if self.__failure is not None: 
+            failure = self.__failure 
+            self.__failure = None 
+            raise_exc_info(failure) 
+ 
+    def run(self, result=None): 
+        with ExceptionStackContext(self._handle_exception): 
+            super(AsyncTestCase, self).run(result) 
+        # As a last resort, if an exception escaped super.run() and wasn't 
+        # re-raised in tearDown, raise it here.  This will cause the 
+        # unittest run to fail messily, but that's better than silently 
+        # ignoring an error. 
+        self.__rethrow() 
+ 
+    def stop(self, _arg=None, **kwargs): 
+        """Stops the `.IOLoop`, causing one pending (or future) call to `wait()` 
+        to return. 
+ 
+        Keyword arguments or a single positional argument passed to `stop()` are 
+        saved and will be returned by `wait()`. 
+        """ 
+        assert _arg is None or not kwargs 
+        self.__stop_args = kwargs or _arg 
+        if self.__running: 
+            self.io_loop.stop() 
+            self.__running = False 
+        self.__stopped = True 
+ 
+    def wait(self, condition=None, timeout=None): 
+        """Runs the `.IOLoop` until stop is called or timeout has passed. 
+ 
+        In the event of a timeout, an exception will be thrown. The 
+        default timeout is 5 seconds; it may be overridden with a 
+        ``timeout`` keyword argument or globally with the 
+        ``ASYNC_TEST_TIMEOUT`` environment variable. 
+ 
+        If ``condition`` is not None, the `.IOLoop` will be restarted 
+        after `stop()` until ``condition()`` returns true. 
+ 
+        .. versionchanged:: 3.1 
+           Added the ``ASYNC_TEST_TIMEOUT`` environment variable. 
+        """ 
+        if timeout is None: 
+            timeout = get_async_test_timeout() 
+ 
+        if not self.__stopped: 
+            if timeout: 
+                def timeout_func(): 
+                    try: 
+                        raise self.failureException( 
+                            'Async operation timed out after %s seconds' % 
+                            timeout) 
+                    except Exception: 
+                        self.__failure = sys.exc_info() 
+                    self.stop() 
+                self.__timeout = self.io_loop.add_timeout(self.io_loop.time() + timeout, timeout_func) 
+            while True: 
+                self.__running = True 
+                self.io_loop.start() 
+                if (self.__failure is not None or 
+                        condition is None or condition()): 
+                    break 
+            if self.__timeout is not None: 
+                self.io_loop.remove_timeout(self.__timeout) 
+                self.__timeout = None 
+        assert self.__stopped 
+        self.__stopped = False 
+        self.__rethrow() 
+        result = self.__stop_args 
+        self.__stop_args = None 
+        return result 
+ 
+ 
+class AsyncHTTPTestCase(AsyncTestCase): 
+    """A test case that starts up an HTTP server. 
+ 
+    Subclasses must override `get_app()`, which returns the 
+    `tornado.web.Application` (or other `.HTTPServer` callback) to be tested. 
+    Tests will typically use the provided ``self.http_client`` to fetch 
+    URLs from this server. 
+ 
+    Example, assuming the "Hello, world" example from the user guide is in 
+    ``hello.py``:: 
+ 
+        import hello 
+ 
+        class TestHelloApp(AsyncHTTPTestCase): 
+            def get_app(self): 
+                return hello.make_app() 
+ 
+            def test_homepage(self): 
+                response = self.fetch('/') 
+                self.assertEqual(response.code, 200) 
+                self.assertEqual(response.body, 'Hello, world') 
+ 
+    That call to ``self.fetch()`` is equivalent to :: 
+ 
+        self.http_client.fetch(self.get_url('/'), self.stop) 
+        response = self.wait() 
+ 
+    which illustrates how AsyncTestCase can turn an asynchronous operation, 
+    like ``http_client.fetch()``, into a synchronous operation. If you need 
+    to do other asynchronous operations in tests, you'll probably need to use 
+    ``stop()`` and ``wait()`` yourself. 
+    """ 
+    def setUp(self): 
+        super(AsyncHTTPTestCase, self).setUp() 
+        sock, port = bind_unused_port() 
+        self.__port = port 
+ 
+        self.http_client = self.get_http_client() 
+        self._app = self.get_app() 
+        self.http_server = self.get_http_server() 
+        self.http_server.add_sockets([sock]) 
+ 
+    def get_http_client(self): 
+        return AsyncHTTPClient(io_loop=self.io_loop) 
+ 
+    def get_http_server(self): 
+        return HTTPServer(self._app, io_loop=self.io_loop, 
+                          **self.get_httpserver_options()) 
+ 
+    def get_app(self): 
+        """Should be overridden by subclasses to return a 
+        `tornado.web.Application` or other `.HTTPServer` callback. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def fetch(self, path, **kwargs): 
+        """Convenience method to synchronously fetch a url. 
+ 
+        The given path will be appended to the local server's host and 
+        port.  Any additional kwargs will be passed directly to 
+        `.AsyncHTTPClient.fetch` (and so could be used to pass 
+        ``method="POST"``, ``body="..."``, etc). 
+        """ 
+        self.http_client.fetch(self.get_url(path), self.stop, **kwargs) 
+        return self.wait() 
+ 
+    def get_httpserver_options(self): 
+        """May be overridden by subclasses to return additional 
+        keyword arguments for the server. 
+        """ 
+        return {} 
+ 
+    def get_http_port(self): 
+        """Returns the port used by the server. 
+ 
+        A new port is chosen for each test. 
+        """ 
+        return self.__port 
+ 
+    def get_protocol(self): 
+        return 'http' 
+ 
+    def get_url(self, path): 
+        """Returns an absolute url for the given path on the test server.""" 
+        return '%s://127.0.0.1:%s%s' % (self.get_protocol(), 
+                                        self.get_http_port(), path) 
+ 
+    def tearDown(self): 
+        self.http_server.stop() 
+        self.io_loop.run_sync(self.http_server.close_all_connections, 
+                              timeout=get_async_test_timeout()) 
+        if (not IOLoop.initialized() or 
+                self.http_client.io_loop is not IOLoop.instance()): 
+            self.http_client.close() 
+        super(AsyncHTTPTestCase, self).tearDown() 
+ 
+ 
+class AsyncHTTPSTestCase(AsyncHTTPTestCase): 
+    """A test case that starts an HTTPS server. 
+ 
+    Interface is generally the same as `AsyncHTTPTestCase`. 
+    """ 
+    def get_http_client(self): 
+        return AsyncHTTPClient(io_loop=self.io_loop, force_instance=True, 
+                               defaults=dict(validate_cert=False)) 
+ 
+    def get_httpserver_options(self): 
+        return dict(ssl_options=self.get_ssl_options()) 
+ 
+    def get_ssl_options(self): 
+        """May be overridden by subclasses to select SSL options. 
+ 
+        By default includes a self-signed testing certificate. 
+        """ 
+        # Testing keys were generated with: 
+        # openssl req -new -keyout tornado/test/test.key -out tornado/test/test.crt -nodes -days 3650 -x509 
+        module_dir = os.path.dirname(__file__) 
+        return dict( 
+            certfile=os.path.join(module_dir, 'test', 'test.crt'), 
+            keyfile=os.path.join(module_dir, 'test', 'test.key')) 
+ 
+    def get_protocol(self): 
+        return 'https' 
+ 
+ 
+def gen_test(func=None, timeout=None): 
+    """Testing equivalent of ``@gen.coroutine``, to be applied to test methods. 
+ 
+    ``@gen.coroutine`` cannot be used on tests because the `.IOLoop` is not 
+    already running.  ``@gen_test`` should be applied to test methods 
+    on subclasses of `AsyncTestCase`. 
+ 
+    Example:: 
+ 
+        class MyTest(AsyncHTTPTestCase): 
+            @gen_test 
+            def test_something(self): 
+                response = yield gen.Task(self.fetch('/')) 
+ 
+    By default, ``@gen_test`` times out after 5 seconds. The timeout may be 
+    overridden globally with the ``ASYNC_TEST_TIMEOUT`` environment variable, 
+    or for each test with the ``timeout`` keyword argument:: 
+ 
+        class MyTest(AsyncHTTPTestCase): 
+            @gen_test(timeout=10) 
+            def test_something_slow(self): 
+                response = yield gen.Task(self.fetch('/')) 
+ 
+    .. versionadded:: 3.1 
+       The ``timeout`` argument and ``ASYNC_TEST_TIMEOUT`` environment 
+       variable. 
+ 
+    .. versionchanged:: 4.0 
+       The wrapper now passes along ``*args, **kwargs`` so it can be used 
+       on functions with arguments. 
+    """ 
+    if timeout is None: 
+        timeout = get_async_test_timeout() 
+ 
+    def wrap(f): 
+        # Stack up several decorators to allow us to access the generator 
+        # object itself.  In the innermost wrapper, we capture the generator 
+        # and save it in an attribute of self.  Next, we run the wrapped 
+        # function through @gen.coroutine.  Finally, the coroutine is 
+        # wrapped again to make it synchronous with run_sync. 
+        # 
+        # This is a good case study arguing for either some sort of 
+        # extensibility in the gen decorators or cancellation support. 
+        @functools.wraps(f) 
+        def pre_coroutine(self, *args, **kwargs): 
+            result = f(self, *args, **kwargs) 
+            if isinstance(result, GeneratorType) or iscoroutine(result): 
+                self._test_generator = result 
+            else: 
+                self._test_generator = None 
+            return result 
+ 
+        if iscoroutinefunction(f): 
+            coro = pre_coroutine 
+        else: 
+            coro = gen.coroutine(pre_coroutine) 
+ 
+        @functools.wraps(coro) 
+        def post_coroutine(self, *args, **kwargs): 
+            try: 
+                return self.io_loop.run_sync( 
+                    functools.partial(coro, self, *args, **kwargs), 
+                    timeout=timeout) 
+            except TimeoutError as e: 
+                # run_sync raises an error with an unhelpful traceback. 
+                # Throw it back into the generator or coroutine so the stack 
+                # trace is replaced by the point where the test is stopped. 
+                self._test_generator.throw(e) 
+                # In case the test contains an overly broad except clause, 
+                # we may get back here.  In this case re-raise the original 
+                # exception, which is better than nothing. 
+                raise 
+        return post_coroutine 
+ 
+    if func is not None: 
+        # Used like: 
+        #     @gen_test 
+        #     def f(self): 
+        #         pass 
+        return wrap(func) 
+    else: 
+        # Used like @gen_test(timeout=10) 
+        return wrap 
+ 
+ 
+# Without this attribute, nosetests will try to run gen_test as a test 
+# anywhere it is imported. 
+gen_test.__test__ = False  # type: ignore 
+ 
+ 
+class LogTrapTestCase(unittest.TestCase): 
+    """A test case that captures and discards all logging output 
+    if the test passes. 
+ 
+    Some libraries can produce a lot of logging output even when 
+    the test succeeds, so this class can be useful to minimize the noise. 
+    Simply use it as a base class for your test case.  It is safe to combine 
+    with AsyncTestCase via multiple inheritance 
+    (``class MyTestCase(AsyncHTTPTestCase, LogTrapTestCase):``) 
+ 
+    This class assumes that only one log handler is configured and 
+    that it is a `~logging.StreamHandler`.  This is true for both 
+    `logging.basicConfig` and the "pretty logging" configured by 
+    `tornado.options`.  It is not compatible with other log buffering 
+    mechanisms, such as those provided by some test runners. 
+ 
+    .. deprecated:: 4.1 
+       Use the unittest module's ``--buffer`` option instead, or `.ExpectLog`. 
+    """ 
+    def run(self, result=None): 
+        logger = logging.getLogger() 
+        if not logger.handlers: 
+            logging.basicConfig() 
+        handler = logger.handlers[0] 
+        if (len(logger.handlers) > 1 or 
+                not isinstance(handler, logging.StreamHandler)): 
+            # Logging has been configured in a way we don't recognize, 
+            # so just leave it alone. 
+            super(LogTrapTestCase, self).run(result) 
+            return 
+        old_stream = handler.stream 
+        try: 
+            handler.stream = StringIO() 
+            gen_log.info("RUNNING TEST: " + str(self)) 
+            old_error_count = len(result.failures) + len(result.errors) 
+            super(LogTrapTestCase, self).run(result) 
+            new_error_count = len(result.failures) + len(result.errors) 
+            if new_error_count != old_error_count: 
+                old_stream.write(handler.stream.getvalue()) 
+        finally: 
+            handler.stream = old_stream 
+ 
+ 
+class ExpectLog(logging.Filter): 
+    """Context manager to capture and suppress expected log output. 
+ 
+    Useful to make tests of error conditions less noisy, while still 
+    leaving unexpected log entries visible.  *Not thread safe.* 
+ 
+    The attribute ``logged_stack`` is set to true if any exception 
+    stack trace was logged. 
+ 
+    Usage:: 
+ 
+        with ExpectLog('tornado.application', "Uncaught exception"): 
+            error_response = self.fetch("/some_page") 
+ 
+    .. versionchanged:: 4.3 
+       Added the ``logged_stack`` attribute. 
+    """ 
+    def __init__(self, logger, regex, required=True): 
+        """Constructs an ExpectLog context manager. 
+ 
+        :param logger: Logger object (or name of logger) to watch.  Pass 
+            an empty string to watch the root logger. 
+        :param regex: Regular expression to match.  Any log entries on 
+            the specified logger that match this regex will be suppressed. 
+        :param required: If true, an exception will be raised if the end of 
+            the ``with`` statement is reached without matching any log entries. 
+        """ 
+        if isinstance(logger, basestring_type): 
+            logger = logging.getLogger(logger) 
+        self.logger = logger 
+        self.regex = re.compile(regex) 
+        self.required = required 
+        self.matched = False 
+        self.logged_stack = False 
+ 
+    def filter(self, record): 
+        if record.exc_info: 
+            self.logged_stack = True 
+        message = record.getMessage() 
+        if self.regex.match(message): 
+            self.matched = True 
+            return False 
+        return True 
+ 
+    def __enter__(self): 
+        self.logger.addFilter(self) 
+        return self 
+ 
+    def __exit__(self, typ, value, tb): 
+        self.logger.removeFilter(self) 
+        if not typ and self.required and not self.matched: 
+            raise Exception("did not get expected log message") 
+ 
+ 
+def main(**kwargs): 
+    """A simple test runner. 
+ 
+    This test runner is essentially equivalent to `unittest.main` from 
+    the standard library, but adds support for tornado-style option 
+    parsing and log formatting. It is *not* necessary to use this 
+    `main` function to run tests using `AsyncTestCase`; these tests 
+    are self-contained and can run with any test runner. 
+ 
+    The easiest way to run a test is via the command line:: 
+ 
+        python -m tornado.testing tornado.test.stack_context_test 
+ 
+    See the standard library unittest module for ways in which tests can 
+    be specified. 
+ 
+    Projects with many tests may wish to define a test script like 
+    ``tornado/test/runtests.py``.  This script should define a method 
+    ``all()`` which returns a test suite and then call 
+    `tornado.testing.main()`.  Note that even when a test script is 
+    used, the ``all()`` test suite may be overridden by naming a 
+    single test on the command line:: 
+ 
+        # Runs all tests 
+        python -m tornado.test.runtests 
+        # Runs one test 
+        python -m tornado.test.runtests tornado.test.stack_context_test 
+ 
+    Additional keyword arguments passed through to ``unittest.main()``. 
+    For example, use ``tornado.testing.main(verbosity=2)`` 
+    to show many test details as they are run. 
     See http://docs.python.org/library/unittest.html#unittest.main
-    for full argument list.
-    """
-    from tornado.options import define, options, parse_command_line
-
-    define('exception_on_interrupt', type=bool, default=True,
-           help=("If true (default), ctrl-c raises a KeyboardInterrupt "
-                 "exception.  This prints a stack trace but cannot interrupt "
-                 "certain operations.  If false, the process is more reliably "
-                 "killed, but does not print a stack trace."))
-
-    # support the same options as unittest's command-line interface
-    define('verbose', type=bool)
-    define('quiet', type=bool)
-    define('failfast', type=bool)
-    define('catch', type=bool)
-    define('buffer', type=bool)
-
-    argv = [sys.argv[0]] + parse_command_line(sys.argv)
-
-    if not options.exception_on_interrupt:
-        signal.signal(signal.SIGINT, signal.SIG_DFL)
-
-    if options.verbose is not None:
-        kwargs['verbosity'] = 2
-    if options.quiet is not None:
-        kwargs['verbosity'] = 0
-    if options.failfast is not None:
-        kwargs['failfast'] = True
-    if options.catch is not None:
-        kwargs['catchbreak'] = True
-    if options.buffer is not None:
-        kwargs['buffer'] = True
-
-    if __name__ == '__main__' and len(argv) == 1:
-        print("No tests specified", file=sys.stderr)
-        sys.exit(1)
-    try:
-        # In order to be able to run tests by their fully-qualified name
-        # on the command line without importing all tests here,
-        # module must be set to None.  Python 3.2's unittest.main ignores
-        # defaultTest if no module is given (it tries to do its own
-        # test discovery, which is incompatible with auto2to3), so don't
-        # set module if we're not asking for a specific test.
-        if len(argv) > 1:
-            unittest.main(module=None, argv=argv, **kwargs)
-        else:
-            unittest.main(defaultTest="all", argv=argv, **kwargs)
-    except SystemExit as e:
-        if e.code == 0:
-            gen_log.info('PASS')
-        else:
-            gen_log.error('FAIL')
-        raise
-
-
-if __name__ == '__main__':
-    main()
+    for full argument list. 
+    """ 
+    from tornado.options import define, options, parse_command_line 
+ 
+    define('exception_on_interrupt', type=bool, default=True, 
+           help=("If true (default), ctrl-c raises a KeyboardInterrupt " 
+                 "exception.  This prints a stack trace but cannot interrupt " 
+                 "certain operations.  If false, the process is more reliably " 
+                 "killed, but does not print a stack trace.")) 
+ 
+    # support the same options as unittest's command-line interface 
+    define('verbose', type=bool) 
+    define('quiet', type=bool) 
+    define('failfast', type=bool) 
+    define('catch', type=bool) 
+    define('buffer', type=bool) 
+ 
+    argv = [sys.argv[0]] + parse_command_line(sys.argv) 
+ 
+    if not options.exception_on_interrupt: 
+        signal.signal(signal.SIGINT, signal.SIG_DFL) 
+ 
+    if options.verbose is not None: 
+        kwargs['verbosity'] = 2 
+    if options.quiet is not None: 
+        kwargs['verbosity'] = 0 
+    if options.failfast is not None: 
+        kwargs['failfast'] = True 
+    if options.catch is not None: 
+        kwargs['catchbreak'] = True 
+    if options.buffer is not None: 
+        kwargs['buffer'] = True 
+ 
+    if __name__ == '__main__' and len(argv) == 1: 
+        print("No tests specified", file=sys.stderr) 
+        sys.exit(1) 
+    try: 
+        # In order to be able to run tests by their fully-qualified name 
+        # on the command line without importing all tests here, 
+        # module must be set to None.  Python 3.2's unittest.main ignores 
+        # defaultTest if no module is given (it tries to do its own 
+        # test discovery, which is incompatible with auto2to3), so don't 
+        # set module if we're not asking for a specific test. 
+        if len(argv) > 1: 
+            unittest.main(module=None, argv=argv, **kwargs) 
+        else: 
+            unittest.main(defaultTest="all", argv=argv, **kwargs) 
+    except SystemExit as e: 
+        if e.code == 0: 
+            gen_log.info('PASS') 
+        else: 
+            gen_log.error('FAIL') 
+        raise 
+ 
+ 
+if __name__ == '__main__': 
+    main() 
diff --git a/contrib/python/tornado/tornado-4/tornado/util.py b/contrib/python/tornado/tornado-4/tornado/util.py
index 981b94c8ea..e0a1b280fa 100644
--- a/contrib/python/tornado/tornado-4/tornado/util.py
+++ b/contrib/python/tornado/tornado-4/tornado/util.py
@@ -1,475 +1,475 @@
-"""Miscellaneous utility functions and classes.
-
-This module is used internally by Tornado.  It is not necessarily expected
-that the functions and classes defined here will be useful to other
-applications, but they are documented here in case they are.
-
-The one public-facing part of this module is the `Configurable` class
-and its `~Configurable.configure` method, which becomes a part of the
-interface of its subclasses, including `.AsyncHTTPClient`, `.IOLoop`,
-and `.Resolver`.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import array
-import atexit
-import os
-import re
-import sys
-import zlib
-
-PY3 = sys.version_info >= (3,)
-
-if PY3:
-    xrange = range
-
-# inspect.getargspec() raises DeprecationWarnings in Python 3.5.
-# The two functions have compatible interfaces for the parts we need.
-if PY3:
-    from inspect import getfullargspec as getargspec
-else:
-    from inspect import getargspec
-
-# Aliases for types that are spelled differently in different Python
-# versions. bytes_type is deprecated and no longer used in Tornado
-# itself but is left in case anyone outside Tornado is using it.
-bytes_type = bytes
-if PY3:
-    unicode_type = str
-    basestring_type = str
-else:
-    # The names unicode and basestring don't exist in py3 so silence flake8.
-    unicode_type = unicode  # noqa
-    basestring_type = basestring  # noqa
-
-
-try:
-    import typing  # noqa
-    from typing import cast
-
-    _ObjectDictBase = typing.Dict[str, typing.Any]
-except ImportError:
-    _ObjectDictBase = dict
-
-    def cast(typ, x):
-        return x
-else:
-    # More imports that are only needed in type comments.
-    import datetime  # noqa
-    import types  # noqa
-    from typing import Any, AnyStr, Union, Optional, Dict, Mapping  # noqa
-    from typing import Tuple, Match, Callable  # noqa
-
-    if PY3:
-        _BaseString = str
-    else:
-        _BaseString = Union[bytes, unicode_type]
-
-
-try:
-    from sys import is_finalizing
-except ImportError:
-    # Emulate it
-    def _get_emulated_is_finalizing():
-        L = []
-        atexit.register(lambda: L.append(None))
-
-        def is_finalizing():
-            # Not referencing any globals here
-            return L != []
-
-        return is_finalizing
-
-    is_finalizing = _get_emulated_is_finalizing()
-
-
-class ObjectDict(_ObjectDictBase):
-    """Makes a dictionary behave like an object, with attribute-style access.
-    """
-    def __getattr__(self, name):
-        # type: (str) -> Any
-        try:
-            return self[name]
-        except KeyError:
-            raise AttributeError(name)
-
-    def __setattr__(self, name, value):
-        # type: (str, Any) -> None
-        self[name] = value
-
-
-class GzipDecompressor(object):
-    """Streaming gzip decompressor.
-
-    The interface is like that of `zlib.decompressobj` (without some of the
-    optional arguments, but it understands gzip headers and checksums.
-    """
-    def __init__(self):
-        # Magic parameter makes zlib module understand gzip header
-        # http://stackoverflow.com/questions/1838699/how-can-i-decompress-a-gzip-stream-with-zlib
-        # This works on cpython and pypy, but not jython.
-        self.decompressobj = zlib.decompressobj(16 + zlib.MAX_WBITS)
-
-    def decompress(self, value, max_length=None):
-        # type: (bytes, Optional[int]) -> bytes
-        """Decompress a chunk, returning newly-available data.
-
-        Some data may be buffered for later processing; `flush` must
-        be called when there is no more input data to ensure that
-        all data was processed.
-
-        If ``max_length`` is given, some input data may be left over
-        in ``unconsumed_tail``; you must retrieve this value and pass
-        it back to a future call to `decompress` if it is not empty.
-        """
-        return self.decompressobj.decompress(value, max_length)
-
-    @property
-    def unconsumed_tail(self):
-        # type: () -> bytes
-        """Returns the unconsumed portion left over
-        """
-        return self.decompressobj.unconsumed_tail
-
-    def flush(self):
-        # type: () -> bytes
-        """Return any remaining buffered data not yet returned by decompress.
-
-        Also checks for errors such as truncated input.
-        No other methods may be called on this object after `flush`.
-        """
-        return self.decompressobj.flush()
-
-
-def import_object(name):
-    # type: (_BaseString) -> Any
-    """Imports an object by name.
-
-    import_object('x') is equivalent to 'import x'.
-    import_object('x.y.z') is equivalent to 'from x.y import z'.
-
-    >>> import tornado.escape
-    >>> import_object('tornado.escape') is tornado.escape
-    True
-    >>> import_object('tornado.escape.utf8') is tornado.escape.utf8
-    True
-    >>> import_object('tornado') is tornado
-    True
-    >>> import_object('tornado.missing_module')
-    Traceback (most recent call last):
-        ...
-    ImportError: No module named missing_module
-    """
-    if not isinstance(name, str):
-        # on python 2 a byte string is required.
-        name = name.encode('utf-8')
-    if name.count('.') == 0:
-        return __import__(name, None, None)
-
-    parts = name.split('.')
-    obj = __import__('.'.join(parts[:-1]), None, None, [parts[-1]], 0)
-    try:
-        return getattr(obj, parts[-1])
-    except AttributeError:
-        raise ImportError("No module named %s" % parts[-1])
-
-
-# Stubs to make mypy happy (and later for actual type-checking).
-def raise_exc_info(exc_info):
-    # type: (Tuple[type, BaseException, types.TracebackType]) -> None
-    pass
-
-
-def exec_in(code, glob, loc=None):
-    # type: (Any, Dict[str, Any], Optional[Mapping[str, Any]]) -> Any
-    if isinstance(code, basestring_type):
-        # exec(string) inherits the caller's future imports; compile
-        # the string first to prevent that.
-        code = compile(code, '<string>', 'exec', dont_inherit=True)
-    exec(code, glob, loc)
-
-
-if PY3:
-    exec("""
-def raise_exc_info(exc_info):
-    try:
-        raise exc_info[1].with_traceback(exc_info[2])
-    finally:
-        exc_info = None
-
-""")
-else:
-    exec("""
-def raise_exc_info(exc_info):
-    raise exc_info[0], exc_info[1], exc_info[2]
-""")
-
-
-def errno_from_exception(e):
-    # type: (BaseException) -> Optional[int]
-    """Provides the errno from an Exception object.
-
-    There are cases that the errno attribute was not set so we pull
-    the errno out of the args but if someone instantiates an Exception
-    without any args you will get a tuple error. So this function
-    abstracts all that behavior to give you a safe way to get the
-    errno.
-    """
-
-    if hasattr(e, 'errno'):
-        return e.errno  # type: ignore
-    elif e.args:
-        return e.args[0]
-    else:
-        return None
-
-
-_alphanum = frozenset(
-    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
-
-
-def _re_unescape_replacement(match):
-    # type: (Match[str]) -> str
-    group = match.group(1)
-    if group[0] in _alphanum:
-        raise ValueError("cannot unescape '\\\\%s'" % group[0])
-    return group
-
-
-_re_unescape_pattern = re.compile(r'\\(.)', re.DOTALL)
-
-
-def re_unescape(s):
-    # type: (str) -> str
-    """Unescape a string escaped by `re.escape`.
-
-    May raise ``ValueError`` for regular expressions which could not
-    have been produced by `re.escape` (for example, strings containing
-    ``\d`` cannot be unescaped).
-
-    .. versionadded:: 4.4
-    """
-    return _re_unescape_pattern.sub(_re_unescape_replacement, s)
-
-
-class Configurable(object):
-    """Base class for configurable interfaces.
-
-    A configurable interface is an (abstract) class whose constructor
-    acts as a factory function for one of its implementation subclasses.
-    The implementation subclass as well as optional keyword arguments to
-    its initializer can be set globally at runtime with `configure`.
-
-    By using the constructor as the factory method, the interface
-    looks like a normal class, `isinstance` works as usual, etc.  This
-    pattern is most useful when the choice of implementation is likely
-    to be a global decision (e.g. when `~select.epoll` is available,
-    always use it instead of `~select.select`), or when a
-    previously-monolithic class has been split into specialized
-    subclasses.
-
-    Configurable subclasses must define the class methods
-    `configurable_base` and `configurable_default`, and use the instance
-    method `initialize` instead of ``__init__``.
-    """
-    __impl_class = None  # type: type
-    __impl_kwargs = None  # type: Dict[str, Any]
-
-    def __new__(cls, *args, **kwargs):
-        base = cls.configurable_base()
-        init_kwargs = {}
-        if cls is base:
-            impl = cls.configured_class()
-            if base.__impl_kwargs:
-                init_kwargs.update(base.__impl_kwargs)
-        else:
-            impl = cls
-        init_kwargs.update(kwargs)
-        instance = super(Configurable, cls).__new__(impl)
-        # initialize vs __init__ chosen for compatibility with AsyncHTTPClient
-        # singleton magic.  If we get rid of that we can switch to __init__
-        # here too.
-        instance.initialize(*args, **init_kwargs)
-        return instance
-
-    @classmethod
-    def configurable_base(cls):
-        # type: () -> Any
-        # TODO: This class needs https://github.com/python/typing/issues/107
-        # to be fully typeable.
-        """Returns the base class of a configurable hierarchy.
-
-        This will normally return the class in which it is defined.
-        (which is *not* necessarily the same as the cls classmethod parameter).
-        """
-        raise NotImplementedError()
-
-    @classmethod
-    def configurable_default(cls):
-        # type: () -> type
-        """Returns the implementation class to be used if none is configured."""
-        raise NotImplementedError()
-
-    def initialize(self):
-        # type: () -> None
-        """Initialize a `Configurable` subclass instance.
-
-        Configurable classes should use `initialize` instead of ``__init__``.
-
-        .. versionchanged:: 4.2
-           Now accepts positional arguments in addition to keyword arguments.
-        """
-
-    @classmethod
-    def configure(cls, impl, **kwargs):
-        # type: (Any, **Any) -> None
-        """Sets the class to use when the base class is instantiated.
-
-        Keyword arguments will be saved and added to the arguments passed
-        to the constructor.  This can be used to set global defaults for
-        some parameters.
-        """
-        base = cls.configurable_base()
-        if isinstance(impl, (str, unicode_type)):
-            impl = import_object(impl)
-        if impl is not None and not issubclass(impl, cls):
-            raise ValueError("Invalid subclass of %s" % cls)
-        base.__impl_class = impl
-        base.__impl_kwargs = kwargs
-
-    @classmethod
-    def configured_class(cls):
-        # type: () -> type
-        """Returns the currently configured class."""
-        base = cls.configurable_base()
-        if cls.__impl_class is None:
-            base.__impl_class = cls.configurable_default()
-        return base.__impl_class
-
-    @classmethod
-    def _save_configuration(cls):
-        # type: () -> Tuple[type, Dict[str, Any]]
-        base = cls.configurable_base()
-        return (base.__impl_class, base.__impl_kwargs)
-
-    @classmethod
-    def _restore_configuration(cls, saved):
-        # type: (Tuple[type, Dict[str, Any]]) -> None
-        base = cls.configurable_base()
-        base.__impl_class = saved[0]
-        base.__impl_kwargs = saved[1]
-
-
-class ArgReplacer(object):
-    """Replaces one value in an ``args, kwargs`` pair.
-
-    Inspects the function signature to find an argument by name
-    whether it is passed by position or keyword.  For use in decorators
-    and similar wrappers.
-    """
-    def __init__(self, func, name):
-        # type: (Callable, str) -> None
-        self.name = name
-        try:
-            self.arg_pos = self._getargnames(func).index(name)
-        except ValueError:
-            # Not a positional parameter
-            self.arg_pos = None
-
-    def _getargnames(self, func):
-        # type: (Callable) -> List[str]
-        try:
-            return getargspec(func).args
-        except TypeError:
-            if hasattr(func, 'func_code'):
-                # Cython-generated code has all the attributes needed
-                # by inspect.getargspec, but the inspect module only
-                # works with ordinary functions. Inline the portion of
-                # getargspec that we need here. Note that for static
-                # functions the @cython.binding(True) decorator must
-                # be used (for methods it works out of the box).
-                code = func.func_code  # type: ignore
-                return code.co_varnames[:code.co_argcount]
-            raise
-
-    def get_old_value(self, args, kwargs, default=None):
-        # type: (List[Any], Dict[str, Any], Any) -> Any
-        """Returns the old value of the named argument without replacing it.
-
-        Returns ``default`` if the argument is not present.
-        """
-        if self.arg_pos is not None and len(args) > self.arg_pos:
-            return args[self.arg_pos]
-        else:
-            return kwargs.get(self.name, default)
-
-    def replace(self, new_value, args, kwargs):
-        # type: (Any, List[Any], Dict[str, Any]) -> Tuple[Any, List[Any], Dict[str, Any]]
-        """Replace the named argument in ``args, kwargs`` with ``new_value``.
-
-        Returns ``(old_value, args, kwargs)``.  The returned ``args`` and
-        ``kwargs`` objects may not be the same as the input objects, or
-        the input objects may be mutated.
-
-        If the named argument was not found, ``new_value`` will be added
-        to ``kwargs`` and None will be returned as ``old_value``.
-        """
-        if self.arg_pos is not None and len(args) > self.arg_pos:
-            # The arg to replace is passed positionally
-            old_value = args[self.arg_pos]
-            args = list(args)  # *args is normally a tuple
-            args[self.arg_pos] = new_value
-        else:
-            # The arg to replace is either omitted or passed by keyword.
-            old_value = kwargs.get(self.name)
-            kwargs[self.name] = new_value
-        return old_value, args, kwargs
-
-
-def timedelta_to_seconds(td):
-    # type: (datetime.timedelta) -> float
-    """Equivalent to td.total_seconds() (introduced in python 2.7)."""
-    return (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10 ** 6) / float(10 ** 6)
-
-
-def _websocket_mask_python(mask, data):
-    # type: (bytes, bytes) -> bytes
-    """Websocket masking function.
-
-    `mask` is a `bytes` object of length 4; `data` is a `bytes` object of any length.
-    Returns a `bytes` object of the same length as `data` with the mask applied
-    as specified in section 5.3 of RFC 6455.
-
-    This pure-python implementation may be replaced by an optimized version when available.
-    """
-    mask_arr = array.array("B", mask)
-    unmasked_arr = array.array("B", data)
-    for i in xrange(len(data)):
-        unmasked_arr[i] = unmasked_arr[i] ^ mask_arr[i % 4]
-    if PY3:
-        # tostring was deprecated in py32.  It hasn't been removed,
-        # but since we turn on deprecation warnings in our tests
-        # we need to use the right one.
-        return unmasked_arr.tobytes()
-    else:
-        return unmasked_arr.tostring()
-
-
-if (os.environ.get('TORNADO_NO_EXTENSION') or
-        os.environ.get('TORNADO_EXTENSION') == '0'):
-    # These environment variables exist to make it easier to do performance
-    # comparisons; they are not guaranteed to remain supported in the future.
-    _websocket_mask = _websocket_mask_python
-else:
-    try:
-        from tornado.speedups import websocket_mask as _websocket_mask
-    except ImportError:
-        if os.environ.get('TORNADO_EXTENSION') == '1':
-            raise
-        _websocket_mask = _websocket_mask_python
-
-
-def doctests():
-    import doctest
-    return doctest.DocTestSuite()
+"""Miscellaneous utility functions and classes. 
+ 
+This module is used internally by Tornado.  It is not necessarily expected 
+that the functions and classes defined here will be useful to other 
+applications, but they are documented here in case they are. 
+ 
+The one public-facing part of this module is the `Configurable` class 
+and its `~Configurable.configure` method, which becomes a part of the 
+interface of its subclasses, including `.AsyncHTTPClient`, `.IOLoop`, 
+and `.Resolver`. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import array 
+import atexit 
+import os 
+import re 
+import sys 
+import zlib 
+ 
+PY3 = sys.version_info >= (3,) 
+ 
+if PY3: 
+    xrange = range 
+ 
+# inspect.getargspec() raises DeprecationWarnings in Python 3.5. 
+# The two functions have compatible interfaces for the parts we need. 
+if PY3: 
+    from inspect import getfullargspec as getargspec 
+else: 
+    from inspect import getargspec 
+ 
+# Aliases for types that are spelled differently in different Python 
+# versions. bytes_type is deprecated and no longer used in Tornado 
+# itself but is left in case anyone outside Tornado is using it. 
+bytes_type = bytes 
+if PY3: 
+    unicode_type = str 
+    basestring_type = str 
+else: 
+    # The names unicode and basestring don't exist in py3 so silence flake8. 
+    unicode_type = unicode  # noqa 
+    basestring_type = basestring  # noqa 
+ 
+ 
+try: 
+    import typing  # noqa 
+    from typing import cast 
+ 
+    _ObjectDictBase = typing.Dict[str, typing.Any] 
+except ImportError: 
+    _ObjectDictBase = dict 
+ 
+    def cast(typ, x): 
+        return x 
+else: 
+    # More imports that are only needed in type comments. 
+    import datetime  # noqa 
+    import types  # noqa 
+    from typing import Any, AnyStr, Union, Optional, Dict, Mapping  # noqa 
+    from typing import Tuple, Match, Callable  # noqa 
+ 
+    if PY3: 
+        _BaseString = str 
+    else: 
+        _BaseString = Union[bytes, unicode_type] 
+ 
+ 
+try: 
+    from sys import is_finalizing 
+except ImportError: 
+    # Emulate it 
+    def _get_emulated_is_finalizing(): 
+        L = [] 
+        atexit.register(lambda: L.append(None)) 
+ 
+        def is_finalizing(): 
+            # Not referencing any globals here 
+            return L != [] 
+ 
+        return is_finalizing 
+ 
+    is_finalizing = _get_emulated_is_finalizing() 
+ 
+ 
+class ObjectDict(_ObjectDictBase): 
+    """Makes a dictionary behave like an object, with attribute-style access. 
+    """ 
+    def __getattr__(self, name): 
+        # type: (str) -> Any 
+        try: 
+            return self[name] 
+        except KeyError: 
+            raise AttributeError(name) 
+ 
+    def __setattr__(self, name, value): 
+        # type: (str, Any) -> None 
+        self[name] = value 
+ 
+ 
+class GzipDecompressor(object): 
+    """Streaming gzip decompressor. 
+ 
+    The interface is like that of `zlib.decompressobj` (without some of the 
+    optional arguments, but it understands gzip headers and checksums. 
+    """ 
+    def __init__(self): 
+        # Magic parameter makes zlib module understand gzip header 
+        # http://stackoverflow.com/questions/1838699/how-can-i-decompress-a-gzip-stream-with-zlib 
+        # This works on cpython and pypy, but not jython. 
+        self.decompressobj = zlib.decompressobj(16 + zlib.MAX_WBITS) 
+ 
+    def decompress(self, value, max_length=None): 
+        # type: (bytes, Optional[int]) -> bytes 
+        """Decompress a chunk, returning newly-available data. 
+ 
+        Some data may be buffered for later processing; `flush` must 
+        be called when there is no more input data to ensure that 
+        all data was processed. 
+ 
+        If ``max_length`` is given, some input data may be left over 
+        in ``unconsumed_tail``; you must retrieve this value and pass 
+        it back to a future call to `decompress` if it is not empty. 
+        """ 
+        return self.decompressobj.decompress(value, max_length) 
+ 
+    @property 
+    def unconsumed_tail(self): 
+        # type: () -> bytes 
+        """Returns the unconsumed portion left over 
+        """ 
+        return self.decompressobj.unconsumed_tail 
+ 
+    def flush(self): 
+        # type: () -> bytes 
+        """Return any remaining buffered data not yet returned by decompress. 
+ 
+        Also checks for errors such as truncated input. 
+        No other methods may be called on this object after `flush`. 
+        """ 
+        return self.decompressobj.flush() 
+ 
+ 
+def import_object(name): 
+    # type: (_BaseString) -> Any 
+    """Imports an object by name. 
+ 
+    import_object('x') is equivalent to 'import x'. 
+    import_object('x.y.z') is equivalent to 'from x.y import z'. 
+ 
+    >>> import tornado.escape 
+    >>> import_object('tornado.escape') is tornado.escape 
+    True 
+    >>> import_object('tornado.escape.utf8') is tornado.escape.utf8 
+    True 
+    >>> import_object('tornado') is tornado 
+    True 
+    >>> import_object('tornado.missing_module') 
+    Traceback (most recent call last): 
+        ... 
+    ImportError: No module named missing_module 
+    """ 
+    if not isinstance(name, str): 
+        # on python 2 a byte string is required. 
+        name = name.encode('utf-8') 
+    if name.count('.') == 0: 
+        return __import__(name, None, None) 
+ 
+    parts = name.split('.') 
+    obj = __import__('.'.join(parts[:-1]), None, None, [parts[-1]], 0) 
+    try: 
+        return getattr(obj, parts[-1]) 
+    except AttributeError: 
+        raise ImportError("No module named %s" % parts[-1]) 
+ 
+ 
+# Stubs to make mypy happy (and later for actual type-checking). 
+def raise_exc_info(exc_info): 
+    # type: (Tuple[type, BaseException, types.TracebackType]) -> None 
+    pass 
+ 
+ 
+def exec_in(code, glob, loc=None): 
+    # type: (Any, Dict[str, Any], Optional[Mapping[str, Any]]) -> Any 
+    if isinstance(code, basestring_type): 
+        # exec(string) inherits the caller's future imports; compile 
+        # the string first to prevent that. 
+        code = compile(code, '<string>', 'exec', dont_inherit=True) 
+    exec(code, glob, loc) 
+ 
+ 
+if PY3: 
+    exec(""" 
+def raise_exc_info(exc_info): 
+    try: 
+        raise exc_info[1].with_traceback(exc_info[2]) 
+    finally: 
+        exc_info = None 
+ 
+""") 
+else: 
+    exec(""" 
+def raise_exc_info(exc_info): 
+    raise exc_info[0], exc_info[1], exc_info[2] 
+""") 
+ 
+ 
+def errno_from_exception(e): 
+    # type: (BaseException) -> Optional[int] 
+    """Provides the errno from an Exception object. 
+ 
+    There are cases that the errno attribute was not set so we pull 
+    the errno out of the args but if someone instantiates an Exception 
+    without any args you will get a tuple error. So this function 
+    abstracts all that behavior to give you a safe way to get the 
+    errno. 
+    """ 
+ 
+    if hasattr(e, 'errno'): 
+        return e.errno  # type: ignore 
+    elif e.args: 
+        return e.args[0] 
+    else: 
+        return None 
+ 
+ 
+_alphanum = frozenset( 
+    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789") 
+ 
+ 
+def _re_unescape_replacement(match): 
+    # type: (Match[str]) -> str 
+    group = match.group(1) 
+    if group[0] in _alphanum: 
+        raise ValueError("cannot unescape '\\\\%s'" % group[0]) 
+    return group 
+ 
+ 
+_re_unescape_pattern = re.compile(r'\\(.)', re.DOTALL) 
+ 
+ 
+def re_unescape(s): 
+    # type: (str) -> str 
+    """Unescape a string escaped by `re.escape`. 
+ 
+    May raise ``ValueError`` for regular expressions which could not 
+    have been produced by `re.escape` (for example, strings containing 
+    ``\d`` cannot be unescaped). 
+ 
+    .. versionadded:: 4.4 
+    """ 
+    return _re_unescape_pattern.sub(_re_unescape_replacement, s) 
+ 
+ 
+class Configurable(object): 
+    """Base class for configurable interfaces. 
+ 
+    A configurable interface is an (abstract) class whose constructor 
+    acts as a factory function for one of its implementation subclasses. 
+    The implementation subclass as well as optional keyword arguments to 
+    its initializer can be set globally at runtime with `configure`. 
+ 
+    By using the constructor as the factory method, the interface 
+    looks like a normal class, `isinstance` works as usual, etc.  This 
+    pattern is most useful when the choice of implementation is likely 
+    to be a global decision (e.g. when `~select.epoll` is available, 
+    always use it instead of `~select.select`), or when a 
+    previously-monolithic class has been split into specialized 
+    subclasses. 
+ 
+    Configurable subclasses must define the class methods 
+    `configurable_base` and `configurable_default`, and use the instance 
+    method `initialize` instead of ``__init__``. 
+    """ 
+    __impl_class = None  # type: type 
+    __impl_kwargs = None  # type: Dict[str, Any] 
+ 
+    def __new__(cls, *args, **kwargs): 
+        base = cls.configurable_base() 
+        init_kwargs = {} 
+        if cls is base: 
+            impl = cls.configured_class() 
+            if base.__impl_kwargs: 
+                init_kwargs.update(base.__impl_kwargs) 
+        else: 
+            impl = cls 
+        init_kwargs.update(kwargs) 
+        instance = super(Configurable, cls).__new__(impl) 
+        # initialize vs __init__ chosen for compatibility with AsyncHTTPClient 
+        # singleton magic.  If we get rid of that we can switch to __init__ 
+        # here too. 
+        instance.initialize(*args, **init_kwargs) 
+        return instance 
+ 
+    @classmethod 
+    def configurable_base(cls): 
+        # type: () -> Any 
+        # TODO: This class needs https://github.com/python/typing/issues/107 
+        # to be fully typeable. 
+        """Returns the base class of a configurable hierarchy. 
+ 
+        This will normally return the class in which it is defined. 
+        (which is *not* necessarily the same as the cls classmethod parameter). 
+        """ 
+        raise NotImplementedError() 
+ 
+    @classmethod 
+    def configurable_default(cls): 
+        # type: () -> type 
+        """Returns the implementation class to be used if none is configured.""" 
+        raise NotImplementedError() 
+ 
+    def initialize(self): 
+        # type: () -> None 
+        """Initialize a `Configurable` subclass instance. 
+ 
+        Configurable classes should use `initialize` instead of ``__init__``. 
+ 
+        .. versionchanged:: 4.2 
+           Now accepts positional arguments in addition to keyword arguments. 
+        """ 
+ 
+    @classmethod 
+    def configure(cls, impl, **kwargs): 
+        # type: (Any, **Any) -> None 
+        """Sets the class to use when the base class is instantiated. 
+ 
+        Keyword arguments will be saved and added to the arguments passed 
+        to the constructor.  This can be used to set global defaults for 
+        some parameters. 
+        """ 
+        base = cls.configurable_base() 
+        if isinstance(impl, (str, unicode_type)): 
+            impl = import_object(impl) 
+        if impl is not None and not issubclass(impl, cls): 
+            raise ValueError("Invalid subclass of %s" % cls) 
+        base.__impl_class = impl 
+        base.__impl_kwargs = kwargs 
+ 
+    @classmethod 
+    def configured_class(cls): 
+        # type: () -> type 
+        """Returns the currently configured class.""" 
+        base = cls.configurable_base() 
+        if cls.__impl_class is None: 
+            base.__impl_class = cls.configurable_default() 
+        return base.__impl_class 
+ 
+    @classmethod 
+    def _save_configuration(cls): 
+        # type: () -> Tuple[type, Dict[str, Any]] 
+        base = cls.configurable_base() 
+        return (base.__impl_class, base.__impl_kwargs) 
+ 
+    @classmethod 
+    def _restore_configuration(cls, saved): 
+        # type: (Tuple[type, Dict[str, Any]]) -> None 
+        base = cls.configurable_base() 
+        base.__impl_class = saved[0] 
+        base.__impl_kwargs = saved[1] 
+ 
+ 
+class ArgReplacer(object): 
+    """Replaces one value in an ``args, kwargs`` pair. 
+ 
+    Inspects the function signature to find an argument by name 
+    whether it is passed by position or keyword.  For use in decorators 
+    and similar wrappers. 
+    """ 
+    def __init__(self, func, name): 
+        # type: (Callable, str) -> None 
+        self.name = name 
+        try: 
+            self.arg_pos = self._getargnames(func).index(name) 
+        except ValueError: 
+            # Not a positional parameter 
+            self.arg_pos = None 
+ 
+    def _getargnames(self, func): 
+        # type: (Callable) -> List[str] 
+        try: 
+            return getargspec(func).args 
+        except TypeError: 
+            if hasattr(func, 'func_code'): 
+                # Cython-generated code has all the attributes needed 
+                # by inspect.getargspec, but the inspect module only 
+                # works with ordinary functions. Inline the portion of 
+                # getargspec that we need here. Note that for static 
+                # functions the @cython.binding(True) decorator must 
+                # be used (for methods it works out of the box). 
+                code = func.func_code  # type: ignore 
+                return code.co_varnames[:code.co_argcount] 
+            raise 
+ 
+    def get_old_value(self, args, kwargs, default=None): 
+        # type: (List[Any], Dict[str, Any], Any) -> Any 
+        """Returns the old value of the named argument without replacing it. 
+ 
+        Returns ``default`` if the argument is not present. 
+        """ 
+        if self.arg_pos is not None and len(args) > self.arg_pos: 
+            return args[self.arg_pos] 
+        else: 
+            return kwargs.get(self.name, default) 
+ 
+    def replace(self, new_value, args, kwargs): 
+        # type: (Any, List[Any], Dict[str, Any]) -> Tuple[Any, List[Any], Dict[str, Any]] 
+        """Replace the named argument in ``args, kwargs`` with ``new_value``. 
+ 
+        Returns ``(old_value, args, kwargs)``.  The returned ``args`` and 
+        ``kwargs`` objects may not be the same as the input objects, or 
+        the input objects may be mutated. 
+ 
+        If the named argument was not found, ``new_value`` will be added 
+        to ``kwargs`` and None will be returned as ``old_value``. 
+        """ 
+        if self.arg_pos is not None and len(args) > self.arg_pos: 
+            # The arg to replace is passed positionally 
+            old_value = args[self.arg_pos] 
+            args = list(args)  # *args is normally a tuple 
+            args[self.arg_pos] = new_value 
+        else: 
+            # The arg to replace is either omitted or passed by keyword. 
+            old_value = kwargs.get(self.name) 
+            kwargs[self.name] = new_value 
+        return old_value, args, kwargs 
+ 
+ 
+def timedelta_to_seconds(td): 
+    # type: (datetime.timedelta) -> float 
+    """Equivalent to td.total_seconds() (introduced in python 2.7).""" 
+    return (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10 ** 6) / float(10 ** 6) 
+ 
+ 
+def _websocket_mask_python(mask, data): 
+    # type: (bytes, bytes) -> bytes 
+    """Websocket masking function. 
+ 
+    `mask` is a `bytes` object of length 4; `data` is a `bytes` object of any length. 
+    Returns a `bytes` object of the same length as `data` with the mask applied 
+    as specified in section 5.3 of RFC 6455. 
+ 
+    This pure-python implementation may be replaced by an optimized version when available. 
+    """ 
+    mask_arr = array.array("B", mask) 
+    unmasked_arr = array.array("B", data) 
+    for i in xrange(len(data)): 
+        unmasked_arr[i] = unmasked_arr[i] ^ mask_arr[i % 4] 
+    if PY3: 
+        # tostring was deprecated in py32.  It hasn't been removed, 
+        # but since we turn on deprecation warnings in our tests 
+        # we need to use the right one. 
+        return unmasked_arr.tobytes() 
+    else: 
+        return unmasked_arr.tostring() 
+ 
+ 
+if (os.environ.get('TORNADO_NO_EXTENSION') or 
+        os.environ.get('TORNADO_EXTENSION') == '0'): 
+    # These environment variables exist to make it easier to do performance 
+    # comparisons; they are not guaranteed to remain supported in the future. 
+    _websocket_mask = _websocket_mask_python 
+else: 
+    try: 
+        from tornado.speedups import websocket_mask as _websocket_mask 
+    except ImportError: 
+        if os.environ.get('TORNADO_EXTENSION') == '1': 
+            raise 
+        _websocket_mask = _websocket_mask_python 
+ 
+ 
+def doctests(): 
+    import doctest 
+    return doctest.DocTestSuite() 
diff --git a/contrib/python/tornado/tornado-4/tornado/web.py b/contrib/python/tornado/tornado-4/tornado/web.py
index e8d102b50e..e67a867684 100644
--- a/contrib/python/tornado/tornado-4/tornado/web.py
+++ b/contrib/python/tornado/tornado-4/tornado/web.py
@@ -1,3286 +1,3286 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""``tornado.web`` provides a simple web framework with asynchronous
-features that allow it to scale to large numbers of open connections,
-making it ideal for `long polling
-<http://en.wikipedia.org/wiki/Push_technology#Long_polling>`_.
-
-Here is a simple "Hello, world" example app:
-
-.. testcode::
-
-    import tornado.ioloop
-    import tornado.web
-
-    class MainHandler(tornado.web.RequestHandler):
-        def get(self):
-            self.write("Hello, world")
-
-    if __name__ == "__main__":
-        application = tornado.web.Application([
-            (r"/", MainHandler),
-        ])
-        application.listen(8888)
-        tornado.ioloop.IOLoop.current().start()
-
-.. testoutput::
-   :hide:
-
-
-See the :doc:`guide` for additional information.
-
-Thread-safety notes
--------------------
-
-In general, methods on `RequestHandler` and elsewhere in Tornado are
-not thread-safe.  In particular, methods such as
-`~RequestHandler.write()`, `~RequestHandler.finish()`, and
-`~RequestHandler.flush()` must only be called from the main thread.  If
-you use multiple threads it is important to use `.IOLoop.add_callback`
-to transfer control back to the main thread before finishing the
-request.
-
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import base64
-import binascii
-import datetime
-import email.utils
-import functools
-import gzip
-import hashlib
-import hmac
-import mimetypes
-import numbers
-import os.path
-import re
-import stat
-import sys
-import threading
-import time
-import tornado
-import traceback
-import types
-from inspect import isclass
-from io import BytesIO
-
-from tornado.concurrent import Future
-from tornado import escape
-from tornado import gen
-from tornado import httputil
-from tornado import iostream
-from tornado import locale
-from tornado.log import access_log, app_log, gen_log
-from tornado import stack_context
-from tornado import template
-from tornado.escape import utf8, _unicode
-from tornado.routing import (AnyMatches, DefaultHostMatches, HostMatches,
-                             ReversibleRouter, Rule, ReversibleRuleRouter,
-                             URLSpec)
-from tornado.util import (ObjectDict, raise_exc_info,
-                          unicode_type, _websocket_mask, PY3)
-
-url = URLSpec
-
-if PY3:
-    import http.cookies as Cookie
-    import urllib.parse as urlparse
-    from urllib.parse import urlencode
-else:
-    import Cookie
-    import urlparse
-    from urllib import urlencode
-
-try:
-    import typing  # noqa
-
-    # The following types are accepted by RequestHandler.set_header
-    # and related methods.
-    _HeaderTypes = typing.Union[bytes, unicode_type,
-                                numbers.Integral, datetime.datetime]
-except ImportError:
-    pass
-
-
-MIN_SUPPORTED_SIGNED_VALUE_VERSION = 1
-"""The oldest signed value version supported by this version of Tornado.
-
-Signed values older than this version cannot be decoded.
-
-.. versionadded:: 3.2.1
-"""
-
-MAX_SUPPORTED_SIGNED_VALUE_VERSION = 2
-"""The newest signed value version supported by this version of Tornado.
-
-Signed values newer than this version cannot be decoded.
-
-.. versionadded:: 3.2.1
-"""
-
-DEFAULT_SIGNED_VALUE_VERSION = 2
-"""The signed value version produced by `.RequestHandler.create_signed_value`.
-
-May be overridden by passing a ``version`` keyword argument.
-
-.. versionadded:: 3.2.1
-"""
-
-DEFAULT_SIGNED_VALUE_MIN_VERSION = 1
-"""The oldest signed value accepted by `.RequestHandler.get_secure_cookie`.
-
-May be overridden by passing a ``min_version`` keyword argument.
-
-.. versionadded:: 3.2.1
-"""
-
-
-class RequestHandler(object):
-    """Base class for HTTP request handlers.
-
-    Subclasses must define at least one of the methods defined in the
-    "Entry points" section below.
-    """
-    SUPPORTED_METHODS = ("GET", "HEAD", "POST", "DELETE", "PATCH", "PUT",
-                         "OPTIONS")
-
-    _template_loaders = {}  # type: typing.Dict[str, template.BaseLoader]
-    _template_loader_lock = threading.Lock()
-    _remove_control_chars_regex = re.compile(r"[\x00-\x08\x0e-\x1f]")
-
-    def __init__(self, application, request, **kwargs):
-        super(RequestHandler, self).__init__()
-
-        self.application = application
-        self.request = request
-        self._headers_written = False
-        self._finished = False
-        self._auto_finish = True
-        self._transforms = None  # will be set in _execute
-        self._prepared_future = None
-        self._headers = None  # type: httputil.HTTPHeaders
-        self.path_args = None
-        self.path_kwargs = None
-        self.ui = ObjectDict((n, self._ui_method(m)) for n, m in
-                             application.ui_methods.items())
-        # UIModules are available as both `modules` and `_tt_modules` in the
-        # template namespace.  Historically only `modules` was available
-        # but could be clobbered by user additions to the namespace.
-        # The template {% module %} directive looks in `_tt_modules` to avoid
-        # possible conflicts.
-        self.ui["_tt_modules"] = _UIModuleNamespace(self,
-                                                    application.ui_modules)
-        self.ui["modules"] = self.ui["_tt_modules"]
-        self.clear()
-        self.request.connection.set_close_callback(self.on_connection_close)
-        self.initialize(**kwargs)
-
-    def initialize(self):
-        """Hook for subclass initialization. Called for each request.
-
-        A dictionary passed as the third argument of a url spec will be
-        supplied as keyword arguments to initialize().
-
-        Example::
-
-            class ProfileHandler(RequestHandler):
-                def initialize(self, database):
-                    self.database = database
-
-                def get(self, username):
-                    ...
-
-            app = Application([
-                (r'/user/(.*)', ProfileHandler, dict(database=database)),
-                ])
-        """
-        pass
-
-    @property
-    def settings(self):
-        """An alias for `self.application.settings <Application.settings>`."""
-        return self.application.settings
-
-    def head(self, *args, **kwargs):
-        raise HTTPError(405)
-
-    def get(self, *args, **kwargs):
-        raise HTTPError(405)
-
-    def post(self, *args, **kwargs):
-        raise HTTPError(405)
-
-    def delete(self, *args, **kwargs):
-        raise HTTPError(405)
-
-    def patch(self, *args, **kwargs):
-        raise HTTPError(405)
-
-    def put(self, *args, **kwargs):
-        raise HTTPError(405)
-
-    def options(self, *args, **kwargs):
-        raise HTTPError(405)
-
-    def prepare(self):
-        """Called at the beginning of a request before  `get`/`post`/etc.
-
-        Override this method to perform common initialization regardless
-        of the request method.
-
-        Asynchronous support: Decorate this method with `.gen.coroutine`
-        or `.return_future` to make it asynchronous (the
-        `asynchronous` decorator cannot be used on `prepare`).
-        If this method returns a `.Future` execution will not proceed
-        until the `.Future` is done.
-
-        .. versionadded:: 3.1
-           Asynchronous support.
-        """
-        pass
-
-    def on_finish(self):
-        """Called after the end of a request.
-
-        Override this method to perform cleanup, logging, etc.
-        This method is a counterpart to `prepare`.  ``on_finish`` may
-        not produce any output, as it is called after the response
-        has been sent to the client.
-        """
-        pass
-
-    def on_connection_close(self):
-        """Called in async handlers if the client closed the connection.
-
-        Override this to clean up resources associated with
-        long-lived connections.  Note that this method is called only if
-        the connection was closed during asynchronous processing; if you
-        need to do cleanup after every request override `on_finish`
-        instead.
-
-        Proxies may keep a connection open for a time (perhaps
-        indefinitely) after the client has gone away, so this method
-        may not be called promptly after the end user closes their
-        connection.
-        """
-        if _has_stream_request_body(self.__class__):
-            if not self.request.body.done():
-                self.request.body.set_exception(iostream.StreamClosedError())
-                self.request.body.exception()
-
-    def clear(self):
-        """Resets all headers and content for this response."""
-        self._headers = httputil.HTTPHeaders({
-            "Server": "TornadoServer/%s" % tornado.version,
-            "Content-Type": "text/html; charset=UTF-8",
-            "Date": httputil.format_timestamp(time.time()),
-        })
-        self.set_default_headers()
-        self._write_buffer = []
-        self._status_code = 200
-        self._reason = httputil.responses[200]
-
-    def set_default_headers(self):
-        """Override this to set HTTP headers at the beginning of the request.
-
-        For example, this is the place to set a custom ``Server`` header.
-        Note that setting such headers in the normal flow of request
-        processing may not do what you want, since headers may be reset
-        during error handling.
-        """
-        pass
-
-    def set_status(self, status_code, reason=None):
-        """Sets the status code for our response.
-
-        :arg int status_code: Response status code. If ``reason`` is ``None``,
-            it must be present in `httplib.responses <http.client.responses>`.
-        :arg string reason: Human-readable reason phrase describing the status
-            code. If ``None``, it will be filled in from
-            `httplib.responses <http.client.responses>`.
-        """
-        self._status_code = status_code
-        if reason is not None:
-            self._reason = escape.native_str(reason)
-        else:
-            try:
-                self._reason = httputil.responses[status_code]
-            except KeyError:
-                raise ValueError("unknown status code %d" % status_code)
-
-    def get_status(self):
-        """Returns the status code for our response."""
-        return self._status_code
-
-    def set_header(self, name, value):
-        # type: (str, _HeaderTypes) -> None
-        """Sets the given response header name and value.
-
-        If a datetime is given, we automatically format it according to the
-        HTTP specification. If the value is not a string, we convert it to
-        a string. All header values are then encoded as UTF-8.
-        """
-        self._headers[name] = self._convert_header_value(value)
-
-    def add_header(self, name, value):
-        # type: (str, _HeaderTypes) -> None
-        """Adds the given response header and value.
-
-        Unlike `set_header`, `add_header` may be called multiple times
-        to return multiple values for the same header.
-        """
-        self._headers.add(name, self._convert_header_value(value))
-
-    def clear_header(self, name):
-        """Clears an outgoing header, undoing a previous `set_header` call.
-
-        Note that this method does not apply to multi-valued headers
-        set by `add_header`.
-        """
-        if name in self._headers:
-            del self._headers[name]
-
-    _INVALID_HEADER_CHAR_RE = re.compile(r"[\x00-\x1f]")
-
-    def _convert_header_value(self, value):
-        # type: (_HeaderTypes) -> str
-
-        # Convert the input value to a str. This type check is a bit
-        # subtle: The bytes case only executes on python 3, and the
-        # unicode case only executes on python 2, because the other
-        # cases are covered by the first match for str.
-        if isinstance(value, str):
-            retval = value
-        elif isinstance(value, bytes):  # py3
-            # Non-ascii characters in headers are not well supported,
-            # but if you pass bytes, use latin1 so they pass through as-is.
-            retval = value.decode('latin1')
-        elif isinstance(value, unicode_type):  # py2
-            # TODO: This is inconsistent with the use of latin1 above,
-            # but it's been that way for a long time. Should it change?
-            retval = escape.utf8(value)
-        elif isinstance(value, numbers.Integral):
-            # return immediately since we know the converted value will be safe
-            return str(value)
-        elif isinstance(value, datetime.datetime):
-            return httputil.format_timestamp(value)
-        else:
-            raise TypeError("Unsupported header value %r" % value)
-        # If \n is allowed into the header, it is possible to inject
-        # additional headers or split the request.
-        if RequestHandler._INVALID_HEADER_CHAR_RE.search(retval):
-            raise ValueError("Unsafe header value %r", retval)
-        return retval
-
-    _ARG_DEFAULT = object()
-
-    def get_argument(self, name, default=_ARG_DEFAULT, strip=True):
-        """Returns the value of the argument with the given name.
-
-        If default is not provided, the argument is considered to be
-        required, and we raise a `MissingArgumentError` if it is missing.
-
-        If the argument appears in the url more than once, we return the
-        last value.
-
-        The returned value is always unicode.
-        """
-        return self._get_argument(name, default, self.request.arguments, strip)
-
-    def get_arguments(self, name, strip=True):
-        """Returns a list of the arguments with the given name.
-
-        If the argument is not present, returns an empty list.
-
-        The returned values are always unicode.
-        """
-
-        # Make sure `get_arguments` isn't accidentally being called with a
-        # positional argument that's assumed to be a default (like in
-        # `get_argument`.)
-        assert isinstance(strip, bool)
-
-        return self._get_arguments(name, self.request.arguments, strip)
-
-    def get_body_argument(self, name, default=_ARG_DEFAULT, strip=True):
-        """Returns the value of the argument with the given name
-        from the request body.
-
-        If default is not provided, the argument is considered to be
-        required, and we raise a `MissingArgumentError` if it is missing.
-
-        If the argument appears in the url more than once, we return the
-        last value.
-
-        The returned value is always unicode.
-
-        .. versionadded:: 3.2
-        """
-        return self._get_argument(name, default, self.request.body_arguments,
-                                  strip)
-
-    def get_body_arguments(self, name, strip=True):
-        """Returns a list of the body arguments with the given name.
-
-        If the argument is not present, returns an empty list.
-
-        The returned values are always unicode.
-
-        .. versionadded:: 3.2
-        """
-        return self._get_arguments(name, self.request.body_arguments, strip)
-
-    def get_query_argument(self, name, default=_ARG_DEFAULT, strip=True):
-        """Returns the value of the argument with the given name
-        from the request query string.
-
-        If default is not provided, the argument is considered to be
-        required, and we raise a `MissingArgumentError` if it is missing.
-
-        If the argument appears in the url more than once, we return the
-        last value.
-
-        The returned value is always unicode.
-
-        .. versionadded:: 3.2
-        """
-        return self._get_argument(name, default,
-                                  self.request.query_arguments, strip)
-
-    def get_query_arguments(self, name, strip=True):
-        """Returns a list of the query arguments with the given name.
-
-        If the argument is not present, returns an empty list.
-
-        The returned values are always unicode.
-
-        .. versionadded:: 3.2
-        """
-        return self._get_arguments(name, self.request.query_arguments, strip)
-
-    def _get_argument(self, name, default, source, strip=True):
-        args = self._get_arguments(name, source, strip=strip)
-        if not args:
-            if default is self._ARG_DEFAULT:
-                raise MissingArgumentError(name)
-            return default
-        return args[-1]
-
-    def _get_arguments(self, name, source, strip=True):
-        values = []
-        for v in source.get(name, []):
-            v = self.decode_argument(v, name=name)
-            if isinstance(v, unicode_type):
-                # Get rid of any weird control chars (unless decoding gave
-                # us bytes, in which case leave it alone)
-                v = RequestHandler._remove_control_chars_regex.sub(" ", v)
-            if strip:
-                v = v.strip()
-            values.append(v)
-        return values
-
-    def decode_argument(self, value, name=None):
-        """Decodes an argument from the request.
-
-        The argument has been percent-decoded and is now a byte string.
-        By default, this method decodes the argument as utf-8 and returns
-        a unicode string, but this may be overridden in subclasses.
-
-        This method is used as a filter for both `get_argument()` and for
-        values extracted from the url and passed to `get()`/`post()`/etc.
-
-        The name of the argument is provided if known, but may be None
-        (e.g. for unnamed groups in the url regex).
-        """
-        try:
-            return _unicode(value)
-        except UnicodeDecodeError:
-            raise HTTPError(400, "Invalid unicode in %s: %r" %
-                            (name or "url", value[:40]))
-
-    @property
-    def cookies(self):
-        """An alias for
-        `self.request.cookies <.httputil.HTTPServerRequest.cookies>`."""
-        return self.request.cookies
-
-    def get_cookie(self, name, default=None):
-        """Gets the value of the cookie with the given name, else default."""
-        if self.request.cookies is not None and name in self.request.cookies:
-            return self.request.cookies[name].value
-        return default
-
-    def set_cookie(self, name, value, domain=None, expires=None, path="/",
-                   expires_days=None, **kwargs):
-        """Sets the given cookie name/value with the given options.
-
-        Additional keyword arguments are set on the Cookie.Morsel
-        directly.
-        See https://docs.python.org/2/library/cookie.html#Cookie.Morsel
-        for available attributes.
-        """
-        # The cookie library only accepts type str, in both python 2 and 3
-        name = escape.native_str(name)
-        value = escape.native_str(value)
-        if re.search(r"[\x00-\x20]", name + value):
-            # Don't let us accidentally inject bad stuff
-            raise ValueError("Invalid cookie %r: %r" % (name, value))
-        if not hasattr(self, "_new_cookie"):
-            self._new_cookie = Cookie.SimpleCookie()
-        if name in self._new_cookie:
-            del self._new_cookie[name]
-        self._new_cookie[name] = value
-        morsel = self._new_cookie[name]
-        if domain:
-            morsel["domain"] = domain
-        if expires_days is not None and not expires:
-            expires = datetime.datetime.utcnow() + datetime.timedelta(
-                days=expires_days)
-        if expires:
-            morsel["expires"] = httputil.format_timestamp(expires)
-        if path:
-            morsel["path"] = path
-        for k, v in kwargs.items():
-            if k == 'max_age':
-                k = 'max-age'
-
-            # skip falsy values for httponly and secure flags because
-            # SimpleCookie sets them regardless
-            if k in ['httponly', 'secure'] and not v:
-                continue
-
-            morsel[k] = v
-
-    def clear_cookie(self, name, path="/", domain=None):
-        """Deletes the cookie with the given name.
-
-        Due to limitations of the cookie protocol, you must pass the same
-        path and domain to clear a cookie as were used when that cookie
-        was set (but there is no way to find out on the server side
-        which values were used for a given cookie).
-        """
-        expires = datetime.datetime.utcnow() - datetime.timedelta(days=365)
-        self.set_cookie(name, value="", path=path, expires=expires,
-                        domain=domain)
-
-    def clear_all_cookies(self, path="/", domain=None):
-        """Deletes all the cookies the user sent with this request.
-
-        See `clear_cookie` for more information on the path and domain
-        parameters.
-
-        .. versionchanged:: 3.2
-
-           Added the ``path`` and ``domain`` parameters.
-        """
-        for name in self.request.cookies:
-            self.clear_cookie(name, path=path, domain=domain)
-
-    def set_secure_cookie(self, name, value, expires_days=30, version=None,
-                          **kwargs):
-        """Signs and timestamps a cookie so it cannot be forged.
-
-        You must specify the ``cookie_secret`` setting in your Application
-        to use this method. It should be a long, random sequence of bytes
-        to be used as the HMAC secret for the signature.
-
-        To read a cookie set with this method, use `get_secure_cookie()`.
-
-        Note that the ``expires_days`` parameter sets the lifetime of the
-        cookie in the browser, but is independent of the ``max_age_days``
-        parameter to `get_secure_cookie`.
-
-        Secure cookies may contain arbitrary byte values, not just unicode
-        strings (unlike regular cookies)
-
-        .. versionchanged:: 3.2.1
-
-           Added the ``version`` argument.  Introduced cookie version 2
-           and made it the default.
-        """
-        self.set_cookie(name, self.create_signed_value(name, value,
-                                                       version=version),
-                        expires_days=expires_days, **kwargs)
-
-    def create_signed_value(self, name, value, version=None):
-        """Signs and timestamps a string so it cannot be forged.
-
-        Normally used via set_secure_cookie, but provided as a separate
-        method for non-cookie uses.  To decode a value not stored
-        as a cookie use the optional value argument to get_secure_cookie.
-
-        .. versionchanged:: 3.2.1
-
-           Added the ``version`` argument.  Introduced cookie version 2
-           and made it the default.
-        """
-        self.require_setting("cookie_secret", "secure cookies")
-        secret = self.application.settings["cookie_secret"]
-        key_version = None
-        if isinstance(secret, dict):
-            if self.application.settings.get("key_version") is None:
-                raise Exception("key_version setting must be used for secret_key dicts")
-            key_version = self.application.settings["key_version"]
-
-        return create_signed_value(secret, name, value, version=version,
-                                   key_version=key_version)
-
-    def get_secure_cookie(self, name, value=None, max_age_days=31,
-                          min_version=None):
-        """Returns the given signed cookie if it validates, or None.
-
-        The decoded cookie value is returned as a byte string (unlike
-        `get_cookie`).
-
-        .. versionchanged:: 3.2.1
-
-           Added the ``min_version`` argument.  Introduced cookie version 2;
-           both versions 1 and 2 are accepted by default.
-        """
-        self.require_setting("cookie_secret", "secure cookies")
-        if value is None:
-            value = self.get_cookie(name)
-        return decode_signed_value(self.application.settings["cookie_secret"],
-                                   name, value, max_age_days=max_age_days,
-                                   min_version=min_version)
-
-    def get_secure_cookie_key_version(self, name, value=None):
-        """Returns the signing key version of the secure cookie.
-
-        The version is returned as int.
-        """
-        self.require_setting("cookie_secret", "secure cookies")
-        if value is None:
-            value = self.get_cookie(name)
-        return get_signature_key_version(value)
-
-    def redirect(self, url, permanent=False, status=None):
-        """Sends a redirect to the given (optionally relative) URL.
-
-        If the ``status`` argument is specified, that value is used as the
-        HTTP status code; otherwise either 301 (permanent) or 302
-        (temporary) is chosen based on the ``permanent`` argument.
-        The default is 302 (temporary).
-        """
-        if self._headers_written:
-            raise Exception("Cannot redirect after headers have been written")
-        if status is None:
-            status = 301 if permanent else 302
-        else:
-            assert isinstance(status, int) and 300 <= status <= 399
-        self.set_status(status)
-        self.set_header("Location", utf8(url))
-        self.finish()
-
-    def write(self, chunk):
-        """Writes the given chunk to the output buffer.
-
-        To write the output to the network, use the flush() method below.
-
-        If the given chunk is a dictionary, we write it as JSON and set
-        the Content-Type of the response to be ``application/json``.
-        (if you want to send JSON as a different ``Content-Type``, call
-        set_header *after* calling write()).
-
-        Note that lists are not converted to JSON because of a potential
-        cross-site security vulnerability.  All JSON output should be
-        wrapped in a dictionary.  More details at
-        http://haacked.com/archive/2009/06/25/json-hijacking.aspx/ and
-        https://github.com/facebook/tornado/issues/1009
-        """
-        if self._finished:
-            raise RuntimeError("Cannot write() after finish()")
-        if not isinstance(chunk, (bytes, unicode_type, dict)):
-            message = "write() only accepts bytes, unicode, and dict objects"
-            if isinstance(chunk, list):
-                message += ". Lists not accepted for security reasons; see http://www.tornadoweb.org/en/stable/web.html#tornado.web.RequestHandler.write"
-            raise TypeError(message)
-        if isinstance(chunk, dict):
-            chunk = escape.json_encode(chunk)
-            self.set_header("Content-Type", "application/json; charset=UTF-8")
-        chunk = utf8(chunk)
-        self._write_buffer.append(chunk)
-
-    def render(self, template_name, **kwargs):
-        """Renders the template with the given arguments as the response."""
-        if self._finished:
-            raise RuntimeError("Cannot render() after finish()")
-        html = self.render_string(template_name, **kwargs)
-
-        # Insert the additional JS and CSS added by the modules on the page
-        js_embed = []
-        js_files = []
-        css_embed = []
-        css_files = []
-        html_heads = []
-        html_bodies = []
-        for module in getattr(self, "_active_modules", {}).values():
-            embed_part = module.embedded_javascript()
-            if embed_part:
-                js_embed.append(utf8(embed_part))
-            file_part = module.javascript_files()
-            if file_part:
-                if isinstance(file_part, (unicode_type, bytes)):
-                    js_files.append(file_part)
-                else:
-                    js_files.extend(file_part)
-            embed_part = module.embedded_css()
-            if embed_part:
-                css_embed.append(utf8(embed_part))
-            file_part = module.css_files()
-            if file_part:
-                if isinstance(file_part, (unicode_type, bytes)):
-                    css_files.append(file_part)
-                else:
-                    css_files.extend(file_part)
-            head_part = module.html_head()
-            if head_part:
-                html_heads.append(utf8(head_part))
-            body_part = module.html_body()
-            if body_part:
-                html_bodies.append(utf8(body_part))
-
-        if js_files:
-            # Maintain order of JavaScript files given by modules
-            js = self.render_linked_js(js_files)
-            sloc = html.rindex(b'</body>')
-            html = html[:sloc] + utf8(js) + b'\n' + html[sloc:]
-        if js_embed:
-            js = self.render_embed_js(js_embed)
-            sloc = html.rindex(b'</body>')
-            html = html[:sloc] + js + b'\n' + html[sloc:]
-        if css_files:
-            css = self.render_linked_css(css_files)
-            hloc = html.index(b'</head>')
-            html = html[:hloc] + utf8(css) + b'\n' + html[hloc:]
-        if css_embed:
-            css = self.render_embed_css(css_embed)
-            hloc = html.index(b'</head>')
-            html = html[:hloc] + css + b'\n' + html[hloc:]
-        if html_heads:
-            hloc = html.index(b'</head>')
-            html = html[:hloc] + b''.join(html_heads) + b'\n' + html[hloc:]
-        if html_bodies:
-            hloc = html.index(b'</body>')
-            html = html[:hloc] + b''.join(html_bodies) + b'\n' + html[hloc:]
-        self.finish(html)
-
-    def render_linked_js(self, js_files):
-        """Default method used to render the final js links for the
-        rendered webpage.
-
-        Override this method in a sub-classed controller to change the output.
-        """
-        paths = []
-        unique_paths = set()
-
-        for path in js_files:
-            if not is_absolute(path):
-                path = self.static_url(path)
-            if path not in unique_paths:
-                paths.append(path)
-                unique_paths.add(path)
-
-        return ''.join('<script src="' + escape.xhtml_escape(p) +
-                       '" type="text/javascript"></script>'
-                       for p in paths)
-
-    def render_embed_js(self, js_embed):
-        """Default method used to render the final embedded js for the
-        rendered webpage.
-
-        Override this method in a sub-classed controller to change the output.
-        """
-        return b'<script type="text/javascript">\n//<![CDATA[\n' + \
-               b'\n'.join(js_embed) + b'\n//]]>\n</script>'
-
-    def render_linked_css(self, css_files):
-        """Default method used to render the final css links for the
-        rendered webpage.
-
-        Override this method in a sub-classed controller to change the output.
-        """
-        paths = []
-        unique_paths = set()
-
-        for path in css_files:
-            if not is_absolute(path):
-                path = self.static_url(path)
-            if path not in unique_paths:
-                paths.append(path)
-                unique_paths.add(path)
-
-        return ''.join('<link href="' + escape.xhtml_escape(p) + '" '
-                       'type="text/css" rel="stylesheet"/>'
-                       for p in paths)
-
-    def render_embed_css(self, css_embed):
-        """Default method used to render the final embedded css for the
-        rendered webpage.
-
-        Override this method in a sub-classed controller to change the output.
-        """
-        return b'<style type="text/css">\n' + b'\n'.join(css_embed) + \
-               b'\n</style>'
-
-    def render_string(self, template_name, **kwargs):
-        """Generate the given template with the given arguments.
-
-        We return the generated byte string (in utf8). To generate and
-        write a template as a response, use render() above.
-        """
-        # If no template_path is specified, use the path of the calling file
-        template_path = self.get_template_path()
-        if not template_path:
-            frame = sys._getframe(0)
-            web_file = frame.f_code.co_filename
-            while frame.f_code.co_filename == web_file:
-                frame = frame.f_back
-            template_path = os.path.dirname(frame.f_code.co_filename)
-        with RequestHandler._template_loader_lock:
-            if template_path not in RequestHandler._template_loaders:
-                loader = self.create_template_loader(template_path)
-                RequestHandler._template_loaders[template_path] = loader
-            else:
-                loader = RequestHandler._template_loaders[template_path]
-        t = loader.load(template_name)
-        namespace = self.get_template_namespace()
-        namespace.update(kwargs)
-        return t.generate(**namespace)
-
-    def get_template_namespace(self):
-        """Returns a dictionary to be used as the default template namespace.
-
-        May be overridden by subclasses to add or modify values.
-
-        The results of this method will be combined with additional
-        defaults in the `tornado.template` module and keyword arguments
-        to `render` or `render_string`.
-        """
-        namespace = dict(
-            handler=self,
-            request=self.request,
-            current_user=self.current_user,
-            locale=self.locale,
-            _=self.locale.translate,
-            pgettext=self.locale.pgettext,
-            static_url=self.static_url,
-            xsrf_form_html=self.xsrf_form_html,
-            reverse_url=self.reverse_url
-        )
-        namespace.update(self.ui)
-        return namespace
-
-    def create_template_loader(self, template_path):
-        """Returns a new template loader for the given path.
-
-        May be overridden by subclasses.  By default returns a
-        directory-based loader on the given path, using the
-        ``autoescape`` and ``template_whitespace`` application
-        settings.  If a ``template_loader`` application setting is
-        supplied, uses that instead.
-        """
-        settings = self.application.settings
-        if "template_loader" in settings:
-            return settings["template_loader"]
-        kwargs = {}
-        if "autoescape" in settings:
-            # autoescape=None means "no escaping", so we have to be sure
-            # to only pass this kwarg if the user asked for it.
-            kwargs["autoescape"] = settings["autoescape"]
-        if "template_whitespace" in settings:
-            kwargs["whitespace"] = settings["template_whitespace"]
-        return template.Loader(template_path, **kwargs)
-
-    def flush(self, include_footers=False, callback=None):
-        """Flushes the current output buffer to the network.
-
-        The ``callback`` argument, if given, can be used for flow control:
-        it will be run when all flushed data has been written to the socket.
-        Note that only one flush callback can be outstanding at a time;
-        if another flush occurs before the previous flush's callback
-        has been run, the previous callback will be discarded.
-
-        .. versionchanged:: 4.0
-           Now returns a `.Future` if no callback is given.
-        """
-        chunk = b"".join(self._write_buffer)
-        self._write_buffer = []
-        if not self._headers_written:
-            self._headers_written = True
-            for transform in self._transforms:
-                self._status_code, self._headers, chunk = \
-                    transform.transform_first_chunk(
-                        self._status_code, self._headers,
-                        chunk, include_footers)
-            # Ignore the chunk and only write the headers for HEAD requests
-            if self.request.method == "HEAD":
-                chunk = None
-
-            # Finalize the cookie headers (which have been stored in a side
-            # object so an outgoing cookie could be overwritten before it
-            # is sent).
-            if hasattr(self, "_new_cookie"):
-                for cookie in self._new_cookie.values():
-                    self.add_header("Set-Cookie", cookie.OutputString(None))
-
-            start_line = httputil.ResponseStartLine('',
-                                                    self._status_code,
-                                                    self._reason)
-            return self.request.connection.write_headers(
-                start_line, self._headers, chunk, callback=callback)
-        else:
-            for transform in self._transforms:
-                chunk = transform.transform_chunk(chunk, include_footers)
-            # Ignore the chunk and only write the headers for HEAD requests
-            if self.request.method != "HEAD":
-                return self.request.connection.write(chunk, callback=callback)
-            else:
-                future = Future()
-                future.set_result(None)
-                return future
-
-    def finish(self, chunk=None):
-        """Finishes this response, ending the HTTP request."""
-        if self._finished:
-            raise RuntimeError("finish() called twice")
-
-        if chunk is not None:
-            self.write(chunk)
-
-        # Automatically support ETags and add the Content-Length header if
-        # we have not flushed any content yet.
-        if not self._headers_written:
-            if (self._status_code == 200 and
-                self.request.method in ("GET", "HEAD") and
-                    "Etag" not in self._headers):
-                self.set_etag_header()
-                if self.check_etag_header():
-                    self._write_buffer = []
-                    self.set_status(304)
-            if (self._status_code in (204, 304) or
-                (self._status_code >= 100 and self._status_code < 200)):
-                assert not self._write_buffer, "Cannot send body with %s" % self._status_code
-                self._clear_headers_for_304()
-            elif "Content-Length" not in self._headers:
-                content_length = sum(len(part) for part in self._write_buffer)
-                self.set_header("Content-Length", content_length)
-
-        if hasattr(self.request, "connection"):
-            # Now that the request is finished, clear the callback we
-            # set on the HTTPConnection (which would otherwise prevent the
-            # garbage collection of the RequestHandler when there
-            # are keepalive connections)
-            self.request.connection.set_close_callback(None)
-
-        self.flush(include_footers=True)
-        self.request.finish()
-        self._log()
-        self._finished = True
-        self.on_finish()
-        self._break_cycles()
-
-    def _break_cycles(self):
-        # Break up a reference cycle between this handler and the
-        # _ui_module closures to allow for faster GC on CPython.
-        self.ui = None
-
-    def send_error(self, status_code=500, **kwargs):
-        """Sends the given HTTP error code to the browser.
-
-        If `flush()` has already been called, it is not possible to send
-        an error, so this method will simply terminate the response.
-        If output has been written but not yet flushed, it will be discarded
-        and replaced with the error page.
-
-        Override `write_error()` to customize the error page that is returned.
-        Additional keyword arguments are passed through to `write_error`.
-        """
-        if self._headers_written:
-            gen_log.error("Cannot send error response after headers written")
-            if not self._finished:
-                # If we get an error between writing headers and finishing,
-                # we are unlikely to be able to finish due to a
-                # Content-Length mismatch. Try anyway to release the
-                # socket.
-                try:
-                    self.finish()
-                except Exception:
-                    gen_log.error("Failed to flush partial response",
-                                  exc_info=True)
-            return
-        self.clear()
-
-        reason = kwargs.get('reason')
-        if 'exc_info' in kwargs:
-            exception = kwargs['exc_info'][1]
-            if isinstance(exception, HTTPError) and exception.reason:
-                reason = exception.reason
-        self.set_status(status_code, reason=reason)
-        try:
-            self.write_error(status_code, **kwargs)
-        except Exception:
-            app_log.error("Uncaught exception in write_error", exc_info=True)
-        if not self._finished:
-            self.finish()
-
-    def write_error(self, status_code, **kwargs):
-        """Override to implement custom error pages.
-
-        ``write_error`` may call `write`, `render`, `set_header`, etc
-        to produce output as usual.
-
-        If this error was caused by an uncaught exception (including
-        HTTPError), an ``exc_info`` triple will be available as
-        ``kwargs["exc_info"]``.  Note that this exception may not be
-        the "current" exception for purposes of methods like
-        ``sys.exc_info()`` or ``traceback.format_exc``.
-        """
-        if self.settings.get("serve_traceback") and "exc_info" in kwargs:
-            # in debug mode, try to send a traceback
-            self.set_header('Content-Type', 'text/plain')
-            for line in traceback.format_exception(*kwargs["exc_info"]):
-                self.write(line)
-            self.finish()
-        else:
-            self.finish("<html><title>%(code)d: %(message)s</title>"
-                        "<body>%(code)d: %(message)s</body></html>" % {
-                            "code": status_code,
-                            "message": self._reason,
-                        })
-
-    @property
-    def locale(self):
-        """The locale for the current session.
-
-        Determined by either `get_user_locale`, which you can override to
-        set the locale based on, e.g., a user preference stored in a
-        database, or `get_browser_locale`, which uses the ``Accept-Language``
-        header.
-
-        .. versionchanged: 4.1
-           Added a property setter.
-        """
-        if not hasattr(self, "_locale"):
-            self._locale = self.get_user_locale()
-            if not self._locale:
-                self._locale = self.get_browser_locale()
-                assert self._locale
-        return self._locale
-
-    @locale.setter
-    def locale(self, value):
-        self._locale = value
-
-    def get_user_locale(self):
-        """Override to determine the locale from the authenticated user.
-
-        If None is returned, we fall back to `get_browser_locale()`.
-
-        This method should return a `tornado.locale.Locale` object,
-        most likely obtained via a call like ``tornado.locale.get("en")``
-        """
-        return None
-
-    def get_browser_locale(self, default="en_US"):
-        """Determines the user's locale from ``Accept-Language`` header.
-
-        See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.4
-        """
-        if "Accept-Language" in self.request.headers:
-            languages = self.request.headers["Accept-Language"].split(",")
-            locales = []
-            for language in languages:
-                parts = language.strip().split(";")
-                if len(parts) > 1 and parts[1].startswith("q="):
-                    try:
-                        score = float(parts[1][2:])
-                    except (ValueError, TypeError):
-                        score = 0.0
-                else:
-                    score = 1.0
-                locales.append((parts[0], score))
-            if locales:
-                locales.sort(key=lambda pair: pair[1], reverse=True)
-                codes = [l[0] for l in locales]
-                return locale.get(*codes)
-        return locale.get(default)
-
-    @property
-    def current_user(self):
-        """The authenticated user for this request.
-
-        This is set in one of two ways:
-
-        * A subclass may override `get_current_user()`, which will be called
-          automatically the first time ``self.current_user`` is accessed.
-          `get_current_user()` will only be called once per request,
-          and is cached for future access::
-
-              def get_current_user(self):
-                  user_cookie = self.get_secure_cookie("user")
-                  if user_cookie:
-                      return json.loads(user_cookie)
-                  return None
-
-        * It may be set as a normal variable, typically from an overridden
-          `prepare()`::
-
-              @gen.coroutine
-              def prepare(self):
-                  user_id_cookie = self.get_secure_cookie("user_id")
-                  if user_id_cookie:
-                      self.current_user = yield load_user(user_id_cookie)
-
-        Note that `prepare()` may be a coroutine while `get_current_user()`
-        may not, so the latter form is necessary if loading the user requires
-        asynchronous operations.
-
-        The user object may be any type of the application's choosing.
-        """
-        if not hasattr(self, "_current_user"):
-            self._current_user = self.get_current_user()
-        return self._current_user
-
-    @current_user.setter
-    def current_user(self, value):
-        self._current_user = value
-
-    def get_current_user(self):
-        """Override to determine the current user from, e.g., a cookie.
-
-        This method may not be a coroutine.
-        """
-        return None
-
-    def get_login_url(self):
-        """Override to customize the login URL based on the request.
-
-        By default, we use the ``login_url`` application setting.
-        """
-        self.require_setting("login_url", "@tornado.web.authenticated")
-        return self.application.settings["login_url"]
-
-    def get_template_path(self):
-        """Override to customize template path for each handler.
-
-        By default, we use the ``template_path`` application setting.
-        Return None to load templates relative to the calling file.
-        """
-        return self.application.settings.get("template_path")
-
-    @property
-    def xsrf_token(self):
-        """The XSRF-prevention token for the current user/session.
-
-        To prevent cross-site request forgery, we set an '_xsrf' cookie
-        and include the same '_xsrf' value as an argument with all POST
-        requests. If the two do not match, we reject the form submission
-        as a potential forgery.
-
-        See http://en.wikipedia.org/wiki/Cross-site_request_forgery
-
-        .. versionchanged:: 3.2.2
-           The xsrf token will now be have a random mask applied in every
-           request, which makes it safe to include the token in pages
-           that are compressed.  See http://breachattack.com for more
-           information on the issue fixed by this change.  Old (version 1)
-           cookies will be converted to version 2 when this method is called
-           unless the ``xsrf_cookie_version`` `Application` setting is
-           set to 1.
-
-        .. versionchanged:: 4.3
-           The ``xsrf_cookie_kwargs`` `Application` setting may be
-           used to supply additional cookie options (which will be
-           passed directly to `set_cookie`). For example,
-           ``xsrf_cookie_kwargs=dict(httponly=True, secure=True)``
-           will set the ``secure`` and ``httponly`` flags on the
-           ``_xsrf`` cookie.
-        """
-        if not hasattr(self, "_xsrf_token"):
-            version, token, timestamp = self._get_raw_xsrf_token()
-            output_version = self.settings.get("xsrf_cookie_version", 2)
-            cookie_kwargs = self.settings.get("xsrf_cookie_kwargs", {})
-            if output_version == 1:
-                self._xsrf_token = binascii.b2a_hex(token)
-            elif output_version == 2:
-                mask = os.urandom(4)
-                self._xsrf_token = b"|".join([
-                    b"2",
-                    binascii.b2a_hex(mask),
-                    binascii.b2a_hex(_websocket_mask(mask, token)),
-                    utf8(str(int(timestamp)))])
-            else:
-                raise ValueError("unknown xsrf cookie version %d",
-                                 output_version)
-            if version is None:
-                expires_days = 30 if self.current_user else None
-                self.set_cookie("_xsrf", self._xsrf_token,
-                                expires_days=expires_days,
-                                **cookie_kwargs)
-        return self._xsrf_token
-
-    def _get_raw_xsrf_token(self):
-        """Read or generate the xsrf token in its raw form.
-
-        The raw_xsrf_token is a tuple containing:
-
-        * version: the version of the cookie from which this token was read,
-          or None if we generated a new token in this request.
-        * token: the raw token data; random (non-ascii) bytes.
-        * timestamp: the time this token was generated (will not be accurate
-          for version 1 cookies)
-        """
-        if not hasattr(self, '_raw_xsrf_token'):
-            cookie = self.get_cookie("_xsrf")
-            if cookie:
-                version, token, timestamp = self._decode_xsrf_token(cookie)
-            else:
-                version, token, timestamp = None, None, None
-            if token is None:
-                version = None
-                token = os.urandom(16)
-                timestamp = time.time()
-            self._raw_xsrf_token = (version, token, timestamp)
-        return self._raw_xsrf_token
-
-    def _decode_xsrf_token(self, cookie):
-        """Convert a cookie string into a the tuple form returned by
-        _get_raw_xsrf_token.
-        """
-
-        try:
-            m = _signed_value_version_re.match(utf8(cookie))
-
-            if m:
-                version = int(m.group(1))
-                if version == 2:
-                    _, mask, masked_token, timestamp = cookie.split("|")
-
-                    mask = binascii.a2b_hex(utf8(mask))
-                    token = _websocket_mask(
-                        mask, binascii.a2b_hex(utf8(masked_token)))
-                    timestamp = int(timestamp)
-                    return version, token, timestamp
-                else:
-                    # Treat unknown versions as not present instead of failing.
-                    raise Exception("Unknown xsrf cookie version")
-            else:
-                version = 1
-                try:
-                    token = binascii.a2b_hex(utf8(cookie))
-                except (binascii.Error, TypeError):
-                    token = utf8(cookie)
-                # We don't have a usable timestamp in older versions.
-                timestamp = int(time.time())
-                return (version, token, timestamp)
-        except Exception:
-            # Catch exceptions and return nothing instead of failing.
-            gen_log.debug("Uncaught exception in _decode_xsrf_token",
-                          exc_info=True)
-            return None, None, None
-
-    def check_xsrf_cookie(self):
-        """Verifies that the ``_xsrf`` cookie matches the ``_xsrf`` argument.
-
-        To prevent cross-site request forgery, we set an ``_xsrf``
-        cookie and include the same value as a non-cookie
-        field with all ``POST`` requests. If the two do not match, we
-        reject the form submission as a potential forgery.
-
-        The ``_xsrf`` value may be set as either a form field named ``_xsrf``
-        or in a custom HTTP header named ``X-XSRFToken`` or ``X-CSRFToken``
-        (the latter is accepted for compatibility with Django).
-
-        See http://en.wikipedia.org/wiki/Cross-site_request_forgery
-
-        Prior to release 1.1.1, this check was ignored if the HTTP header
-        ``X-Requested-With: XMLHTTPRequest`` was present.  This exception
-        has been shown to be insecure and has been removed.  For more
-        information please see
-        http://www.djangoproject.com/weblog/2011/feb/08/security/
-        http://weblog.rubyonrails.org/2011/2/8/csrf-protection-bypass-in-ruby-on-rails
-
-        .. versionchanged:: 3.2.2
-           Added support for cookie version 2.  Both versions 1 and 2 are
-           supported.
-        """
-        token = (self.get_argument("_xsrf", None) or
-                 self.request.headers.get("X-Xsrftoken") or
-                 self.request.headers.get("X-Csrftoken"))
-        if not token:
-            raise HTTPError(403, "'_xsrf' argument missing from POST")
-        _, token, _ = self._decode_xsrf_token(token)
-        _, expected_token, _ = self._get_raw_xsrf_token()
-        if not token:
-            raise HTTPError(403, "'_xsrf' argument has invalid format")
-        if not _time_independent_equals(utf8(token), utf8(expected_token)):
-            raise HTTPError(403, "XSRF cookie does not match POST argument")
-
-    def xsrf_form_html(self):
-        """An HTML ``<input/>`` element to be included with all POST forms.
-
-        It defines the ``_xsrf`` input value, which we check on all POST
-        requests to prevent cross-site request forgery. If you have set
-        the ``xsrf_cookies`` application setting, you must include this
-        HTML within all of your HTML forms.
-
-        In a template, this method should be called with ``{% module
-        xsrf_form_html() %}``
-
-        See `check_xsrf_cookie()` above for more information.
-        """
-        return '<input type="hidden" name="_xsrf" value="' + \
-            escape.xhtml_escape(self.xsrf_token) + '"/>'
-
-    def static_url(self, path, include_host=None, **kwargs):
-        """Returns a static URL for the given relative static file path.
-
-        This method requires you set the ``static_path`` setting in your
-        application (which specifies the root directory of your static
-        files).
-
-        This method returns a versioned url (by default appending
-        ``?v=<signature>``), which allows the static files to be
-        cached indefinitely.  This can be disabled by passing
-        ``include_version=False`` (in the default implementation;
-        other static file implementations are not required to support
-        this, but they may support other options).
-
-        By default this method returns URLs relative to the current
-        host, but if ``include_host`` is true the URL returned will be
-        absolute.  If this handler has an ``include_host`` attribute,
-        that value will be used as the default for all `static_url`
-        calls that do not pass ``include_host`` as a keyword argument.
-
-        """
-        self.require_setting("static_path", "static_url")
-        get_url = self.settings.get("static_handler_class",
-                                    StaticFileHandler).make_static_url
-
-        if include_host is None:
-            include_host = getattr(self, "include_host", False)
-
-        if include_host:
-            base = self.request.protocol + "://" + self.request.host
-        else:
-            base = ""
-
-        return base + get_url(self.settings, path, **kwargs)
-
-    def require_setting(self, name, feature="this feature"):
-        """Raises an exception if the given app setting is not defined."""
-        if not self.application.settings.get(name):
-            raise Exception("You must define the '%s' setting in your "
-                            "application to use %s" % (name, feature))
-
-    def reverse_url(self, name, *args):
-        """Alias for `Application.reverse_url`."""
-        return self.application.reverse_url(name, *args)
-
-    def compute_etag(self):
-        """Computes the etag header to be used for this request.
-
-        By default uses a hash of the content written so far.
-
-        May be overridden to provide custom etag implementations,
-        or may return None to disable tornado's default etag support.
-        """
-        hasher = hashlib.sha1()
-        for part in self._write_buffer:
-            hasher.update(part)
-        return '"%s"' % hasher.hexdigest()
-
-    def set_etag_header(self):
-        """Sets the response's Etag header using ``self.compute_etag()``.
-
-        Note: no header will be set if ``compute_etag()`` returns ``None``.
-
-        This method is called automatically when the request is finished.
-        """
-        etag = self.compute_etag()
-        if etag is not None:
-            self.set_header("Etag", etag)
-
-    def check_etag_header(self):
-        """Checks the ``Etag`` header against requests's ``If-None-Match``.
-
-        Returns ``True`` if the request's Etag matches and a 304 should be
-        returned. For example::
-
-            self.set_etag_header()
-            if self.check_etag_header():
-                self.set_status(304)
-                return
-
-        This method is called automatically when the request is finished,
-        but may be called earlier for applications that override
-        `compute_etag` and want to do an early check for ``If-None-Match``
-        before completing the request.  The ``Etag`` header should be set
-        (perhaps with `set_etag_header`) before calling this method.
-        """
-        computed_etag = utf8(self._headers.get("Etag", ""))
-        # Find all weak and strong etag values from If-None-Match header
-        # because RFC 7232 allows multiple etag values in a single header.
-        etags = re.findall(
-            br'\*|(?:W/)?"[^"]*"',
-            utf8(self.request.headers.get("If-None-Match", ""))
-        )
-        if not computed_etag or not etags:
-            return False
-
-        match = False
-        if etags[0] == b'*':
-            match = True
-        else:
-            # Use a weak comparison when comparing entity-tags.
-            def val(x):
-                return x[2:] if x.startswith(b'W/') else x
-
-            for etag in etags:
-                if val(etag) == val(computed_etag):
-                    match = True
-                    break
-        return match
-
-    def _stack_context_handle_exception(self, type, value, traceback):
-        try:
-            # For historical reasons _handle_request_exception only takes
-            # the exception value instead of the full triple,
-            # so re-raise the exception to ensure that it's in
-            # sys.exc_info()
-            raise_exc_info((type, value, traceback))
-        except Exception:
-            self._handle_request_exception(value)
-        return True
-
-    @gen.coroutine
-    def _execute(self, transforms, *args, **kwargs):
-        """Executes this request with the given output transforms."""
-        self._transforms = transforms
-        try:
-            if self.request.method not in self.SUPPORTED_METHODS:
-                raise HTTPError(405)
-            self.path_args = [self.decode_argument(arg) for arg in args]
-            self.path_kwargs = dict((k, self.decode_argument(v, name=k))
-                                    for (k, v) in kwargs.items())
-            # If XSRF cookies are turned on, reject form submissions without
-            # the proper cookie
-            if self.request.method not in ("GET", "HEAD", "OPTIONS") and \
-                    self.application.settings.get("xsrf_cookies"):
-                self.check_xsrf_cookie()
-
-            result = self.prepare()
-            if result is not None:
-                result = yield result
-            if self._prepared_future is not None:
-                # Tell the Application we've finished with prepare()
-                # and are ready for the body to arrive.
-                self._prepared_future.set_result(None)
-            if self._finished:
-                return
-
-            if _has_stream_request_body(self.__class__):
-                # In streaming mode request.body is a Future that signals
-                # the body has been completely received.  The Future has no
-                # result; the data has been passed to self.data_received
-                # instead.
-                try:
-                    yield self.request.body
-                except iostream.StreamClosedError:
-                    return
-
-            method = getattr(self, self.request.method.lower())
-            result = method(*self.path_args, **self.path_kwargs)
-            if result is not None:
-                result = yield result
-            if self._auto_finish and not self._finished:
-                self.finish()
-        except Exception as e:
-            try:
-                self._handle_request_exception(e)
-            except Exception:
-                app_log.error("Exception in exception handler", exc_info=True)
-            if (self._prepared_future is not None and
-                    not self._prepared_future.done()):
-                # In case we failed before setting _prepared_future, do it
-                # now (to unblock the HTTP server).  Note that this is not
-                # in a finally block to avoid GC issues prior to Python 3.4.
-                self._prepared_future.set_result(None)
-
-    def data_received(self, chunk):
-        """Implement this method to handle streamed request data.
-
-        Requires the `.stream_request_body` decorator.
-        """
-        raise NotImplementedError()
-
-    def _log(self):
-        """Logs the current request.
-
-        Sort of deprecated since this functionality was moved to the
-        Application, but left in place for the benefit of existing apps
-        that have overridden this method.
-        """
-        self.application.log_request(self)
-
-    def _request_summary(self):
-        return "%s %s (%s)" % (self.request.method, self.request.uri,
-                               self.request.remote_ip)
-
-    def _handle_request_exception(self, e):
-        if isinstance(e, Finish):
-            # Not an error; just finish the request without logging.
-            if not self._finished:
-                self.finish(*e.args)
-            return
-        try:
-            self.log_exception(*sys.exc_info())
-        except Exception:
-            # An error here should still get a best-effort send_error()
-            # to avoid leaking the connection.
-            app_log.error("Error in exception logger", exc_info=True)
-        if self._finished:
-            # Extra errors after the request has been finished should
-            # be logged, but there is no reason to continue to try and
-            # send a response.
-            return
-        if isinstance(e, HTTPError):
-            if e.status_code not in httputil.responses and not e.reason:
-                gen_log.error("Bad HTTP status code: %d", e.status_code)
-                self.send_error(500, exc_info=sys.exc_info())
-            else:
-                self.send_error(e.status_code, exc_info=sys.exc_info())
-        else:
-            self.send_error(500, exc_info=sys.exc_info())
-
-    def log_exception(self, typ, value, tb):
-        """Override to customize logging of uncaught exceptions.
-
-        By default logs instances of `HTTPError` as warnings without
-        stack traces (on the ``tornado.general`` logger), and all
-        other exceptions as errors with stack traces (on the
-        ``tornado.application`` logger).
-
-        .. versionadded:: 3.1
-        """
-        if isinstance(value, HTTPError):
-            if value.log_message:
-                format = "%d %s: " + value.log_message
-                args = ([value.status_code, self._request_summary()] +
-                        list(value.args))
-                gen_log.warning(format, *args)
-        else:
-            app_log.error("Uncaught exception %s\n%r", self._request_summary(),
-                          self.request, exc_info=(typ, value, tb))
-
-    def _ui_module(self, name, module):
-        def render(*args, **kwargs):
-            if not hasattr(self, "_active_modules"):
-                self._active_modules = {}
-            if name not in self._active_modules:
-                self._active_modules[name] = module(self)
-            rendered = self._active_modules[name].render(*args, **kwargs)
-            return rendered
-        return render
-
-    def _ui_method(self, method):
-        return lambda *args, **kwargs: method(self, *args, **kwargs)
-
-    def _clear_headers_for_304(self):
-        # 304 responses should not contain entity headers (defined in
-        # http://www.w3.org/Protocols/rfc2616/rfc2616-sec7.html#sec7.1)
-        # not explicitly allowed by
-        # http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.5
-        headers = ["Allow", "Content-Encoding", "Content-Language",
-                   "Content-Length", "Content-MD5", "Content-Range",
-                   "Content-Type", "Last-Modified"]
-        for h in headers:
-            self.clear_header(h)
-
-
-def asynchronous(method):
-    """Wrap request handler methods with this if they are asynchronous.
-
-    This decorator is for callback-style asynchronous methods; for
-    coroutines, use the ``@gen.coroutine`` decorator without
-    ``@asynchronous``. (It is legal for legacy reasons to use the two
-    decorators together provided ``@asynchronous`` is first, but
-    ``@asynchronous`` will be ignored in this case)
-
-    This decorator should only be applied to the :ref:`HTTP verb
-    methods <verbs>`; its behavior is undefined for any other method.
-    This decorator does not *make* a method asynchronous; it tells
-    the framework that the method *is* asynchronous.  For this decorator
-    to be useful the method must (at least sometimes) do something
-    asynchronous.
-
-    If this decorator is given, the response is not finished when the
-    method returns. It is up to the request handler to call
-    `self.finish() <RequestHandler.finish>` to finish the HTTP
-    request. Without this decorator, the request is automatically
-    finished when the ``get()`` or ``post()`` method returns. Example:
-
-    .. testcode::
-
-       class MyRequestHandler(RequestHandler):
-           @asynchronous
-           def get(self):
-              http = httpclient.AsyncHTTPClient()
-              http.fetch("http://friendfeed.com/", self._on_download)
-
-           def _on_download(self, response):
-              self.write("Downloaded!")
-              self.finish()
-
-    .. testoutput::
-       :hide:
-
-    .. versionchanged:: 3.1
-       The ability to use ``@gen.coroutine`` without ``@asynchronous``.
-
-    .. versionchanged:: 4.3 Returning anything but ``None`` or a
-       yieldable object from a method decorated with ``@asynchronous``
-       is an error. Such return values were previously ignored silently.
-    """
-    # Delay the IOLoop import because it's not available on app engine.
-    from tornado.ioloop import IOLoop
-
-    @functools.wraps(method)
-    def wrapper(self, *args, **kwargs):
-        self._auto_finish = False
-        with stack_context.ExceptionStackContext(
-                self._stack_context_handle_exception):
-            result = method(self, *args, **kwargs)
-            if result is not None:
-                result = gen.convert_yielded(result)
-
-                # If @asynchronous is used with @gen.coroutine, (but
-                # not @gen.engine), we can automatically finish the
-                # request when the future resolves.  Additionally,
-                # the Future will swallow any exceptions so we need
-                # to throw them back out to the stack context to finish
-                # the request.
-                def future_complete(f):
-                    f.result()
-                    if not self._finished:
-                        self.finish()
-                IOLoop.current().add_future(result, future_complete)
-                # Once we have done this, hide the Future from our
-                # caller (i.e. RequestHandler._when_complete), which
-                # would otherwise set up its own callback and
-                # exception handler (resulting in exceptions being
-                # logged twice).
-                return None
-            return result
-    return wrapper
-
-
-def stream_request_body(cls):
-    """Apply to `RequestHandler` subclasses to enable streaming body support.
-
-    This decorator implies the following changes:
-
-    * `.HTTPServerRequest.body` is undefined, and body arguments will not
-      be included in `RequestHandler.get_argument`.
-    * `RequestHandler.prepare` is called when the request headers have been
-      read instead of after the entire body has been read.
-    * The subclass must define a method ``data_received(self, data):``, which
-      will be called zero or more times as data is available.  Note that
-      if the request has an empty body, ``data_received`` may not be called.
-    * ``prepare`` and ``data_received`` may return Futures (such as via
-      ``@gen.coroutine``, in which case the next method will not be called
-      until those futures have completed.
-    * The regular HTTP method (``post``, ``put``, etc) will be called after
-      the entire body has been read.
-
-    See the `file receiver demo <https://github.com/tornadoweb/tornado/tree/master/demos/file_upload/>`_
-    for example usage.
-    """
-    if not issubclass(cls, RequestHandler):
-        raise TypeError("expected subclass of RequestHandler, got %r", cls)
-    cls._stream_request_body = True
-    return cls
-
-
-def _has_stream_request_body(cls):
-    if not issubclass(cls, RequestHandler):
-        raise TypeError("expected subclass of RequestHandler, got %r", cls)
-    return getattr(cls, '_stream_request_body', False)
-
-
-def removeslash(method):
-    """Use this decorator to remove trailing slashes from the request path.
-
-    For example, a request to ``/foo/`` would redirect to ``/foo`` with this
-    decorator. Your request handler mapping should use a regular expression
-    like ``r'/foo/*'`` in conjunction with using the decorator.
-    """
-    @functools.wraps(method)
-    def wrapper(self, *args, **kwargs):
-        if self.request.path.endswith("/"):
-            if self.request.method in ("GET", "HEAD"):
-                uri = self.request.path.rstrip("/")
-                if uri:  # don't try to redirect '/' to ''
-                    if self.request.query:
-                        uri += "?" + self.request.query
-                    self.redirect(uri, permanent=True)
-                    return
-            else:
-                raise HTTPError(404)
-        return method(self, *args, **kwargs)
-    return wrapper
-
-
-def addslash(method):
-    """Use this decorator to add a missing trailing slash to the request path.
-
-    For example, a request to ``/foo`` would redirect to ``/foo/`` with this
-    decorator. Your request handler mapping should use a regular expression
-    like ``r'/foo/?'`` in conjunction with using the decorator.
-    """
-    @functools.wraps(method)
-    def wrapper(self, *args, **kwargs):
-        if not self.request.path.endswith("/"):
-            if self.request.method in ("GET", "HEAD"):
-                uri = self.request.path + "/"
-                if self.request.query:
-                    uri += "?" + self.request.query
-                self.redirect(uri, permanent=True)
-                return
-            raise HTTPError(404)
-        return method(self, *args, **kwargs)
-    return wrapper
-
-
-class _ApplicationRouter(ReversibleRuleRouter):
-    """Routing implementation used internally by `Application`.
-
-    Provides a binding between `Application` and `RequestHandler`.
-    This implementation extends `~.routing.ReversibleRuleRouter` in a couple of ways:
-        * it allows to use `RequestHandler` subclasses as `~.routing.Rule` target and
-        * it allows to use a list/tuple of rules as `~.routing.Rule` target.
-        ``process_rule`` implementation will substitute this list with an appropriate
-        `_ApplicationRouter` instance.
-    """
-
-    def __init__(self, application, rules=None):
-        assert isinstance(application, Application)
-        self.application = application
-        super(_ApplicationRouter, self).__init__(rules)
-
-    def process_rule(self, rule):
-        rule = super(_ApplicationRouter, self).process_rule(rule)
-
-        if isinstance(rule.target, (list, tuple)):
-            rule.target = _ApplicationRouter(self.application, rule.target)
-
-        return rule
-
-    def get_target_delegate(self, target, request, **target_params):
-        if isclass(target) and issubclass(target, RequestHandler):
-            return self.application.get_handler_delegate(request, target, **target_params)
-
-        return super(_ApplicationRouter, self).get_target_delegate(target, request, **target_params)
-
-
-class Application(ReversibleRouter):
-    """A collection of request handlers that make up a web application.
-
-    Instances of this class are callable and can be passed directly to
-    HTTPServer to serve the application::
-
-        application = web.Application([
-            (r"/", MainPageHandler),
-        ])
-        http_server = httpserver.HTTPServer(application)
-        http_server.listen(8080)
-        ioloop.IOLoop.current().start()
-
-    The constructor for this class takes in a list of `~.routing.Rule`
-    objects or tuples of values corresponding to the arguments of
-    `~.routing.Rule` constructor: ``(matcher, target, [target_kwargs], [name])``,
-    the values in square brackets being optional. The default matcher is
-    `~.routing.PathMatches`, so ``(regexp, target)`` tuples can also be used
-    instead of ``(PathMatches(regexp), target)``.
-
-    A common routing target is a `RequestHandler` subclass, but you can also
-    use lists of rules as a target, which create a nested routing configuration::
-
-        application = web.Application([
-            (HostMatches("example.com"), [
-                (r"/", MainPageHandler),
-                (r"/feed", FeedHandler),
-            ]),
-        ])
-
-    In addition to this you can use nested `~.routing.Router` instances,
-    `~.httputil.HTTPMessageDelegate` subclasses and callables as routing targets
-    (see `~.routing` module docs for more information).
-
-    When we receive requests, we iterate over the list in order and
-    instantiate an instance of the first request class whose regexp
-    matches the request path. The request class can be specified as
-    either a class object or a (fully-qualified) name.
-
-    A dictionary may be passed as the third element (``target_kwargs``)
-    of the tuple, which will be used as keyword arguments to the handler's
-    constructor and `~RequestHandler.initialize` method. This pattern
-    is used for the `StaticFileHandler` in this example (note that a
-    `StaticFileHandler` can be installed automatically with the
-    static_path setting described below)::
-
-        application = web.Application([
-            (r"/static/(.*)", web.StaticFileHandler, {"path": "/var/www"}),
-        ])
-
-    We support virtual hosts with the `add_handlers` method, which takes in
-    a host regular expression as the first argument::
-
-        application.add_handlers(r"www\.myhost\.com", [
-            (r"/article/([0-9]+)", ArticleHandler),
-        ])
-
-    If there's no match for the current request's host, then ``default_host``
-    parameter value is matched against host regular expressions.
-
-    You can serve static files by sending the ``static_path`` setting
-    as a keyword argument. We will serve those files from the
-    ``/static/`` URI (this is configurable with the
-    ``static_url_prefix`` setting), and we will serve ``/favicon.ico``
-    and ``/robots.txt`` from the same directory.  A custom subclass of
-    `StaticFileHandler` can be specified with the
-    ``static_handler_class`` setting.
-
-    .. versionchanged:: 4.5
-       Integration with the new `tornado.routing` module.
-    """
-    def __init__(self, handlers=None, default_host=None, transforms=None,
-                 **settings):
-        if transforms is None:
-            self.transforms = []
-            if settings.get("compress_response") or settings.get("gzip"):
-                self.transforms.append(GZipContentEncoding)
-        else:
-            self.transforms = transforms
-        self.default_host = default_host
-        self.settings = settings
-        self.ui_modules = {'linkify': _linkify,
-                           'xsrf_form_html': _xsrf_form_html,
-                           'Template': TemplateModule,
-                           }
-        self.ui_methods = {}
-        self._load_ui_modules(settings.get("ui_modules", {}))
-        self._load_ui_methods(settings.get("ui_methods", {}))
-        if self.settings.get("static_path"):
-            path = self.settings["static_path"]
-            handlers = list(handlers or [])
-            static_url_prefix = settings.get("static_url_prefix",
-                                             "/static/")
-            static_handler_class = settings.get("static_handler_class",
-                                                StaticFileHandler)
-            static_handler_args = settings.get("static_handler_args", {})
-            static_handler_args['path'] = path
-            for pattern in [re.escape(static_url_prefix) + r"(.*)",
-                            r"/(favicon\.ico)", r"/(robots\.txt)"]:
-                handlers.insert(0, (pattern, static_handler_class,
-                                    static_handler_args))
-
-        if self.settings.get('debug'):
-            self.settings.setdefault('autoreload', True)
-            self.settings.setdefault('compiled_template_cache', False)
-            self.settings.setdefault('static_hash_cache', False)
-            self.settings.setdefault('serve_traceback', True)
-
-        self.wildcard_router = _ApplicationRouter(self, handlers)
-        self.default_router = _ApplicationRouter(self, [
-            Rule(AnyMatches(), self.wildcard_router)
-        ])
-
-        # Automatically reload modified modules
-        if self.settings.get('autoreload'):
-            from tornado import autoreload
-            autoreload.start()
-
-    def listen(self, port, address="", **kwargs):
-        """Starts an HTTP server for this application on the given port.
-
-        This is a convenience alias for creating an `.HTTPServer`
-        object and calling its listen method.  Keyword arguments not
-        supported by `HTTPServer.listen <.TCPServer.listen>` are passed to the
-        `.HTTPServer` constructor.  For advanced uses
-        (e.g. multi-process mode), do not use this method; create an
-        `.HTTPServer` and call its
-        `.TCPServer.bind`/`.TCPServer.start` methods directly.
-
-        Note that after calling this method you still need to call
-        ``IOLoop.current().start()`` to start the server.
-
-        Returns the `.HTTPServer` object.
-
-        .. versionchanged:: 4.3
-           Now returns the `.HTTPServer` object.
-        """
-        # import is here rather than top level because HTTPServer
-        # is not importable on appengine
-        from tornado.httpserver import HTTPServer
-        server = HTTPServer(self, **kwargs)
-        server.listen(port, address)
-        return server
-
-    def add_handlers(self, host_pattern, host_handlers):
-        """Appends the given handlers to our handler list.
-
-        Host patterns are processed sequentially in the order they were
-        added. All matching patterns will be considered.
-        """
-        host_matcher = HostMatches(host_pattern)
-        rule = Rule(host_matcher, _ApplicationRouter(self, host_handlers))
-
-        self.default_router.rules.insert(-1, rule)
-
-        if self.default_host is not None:
-            self.wildcard_router.add_rules([(
-                DefaultHostMatches(self, host_matcher.host_pattern),
-                host_handlers
-            )])
-
-    def add_transform(self, transform_class):
-        self.transforms.append(transform_class)
-
-    def _load_ui_methods(self, methods):
-        if isinstance(methods, types.ModuleType):
-            self._load_ui_methods(dict((n, getattr(methods, n))
-                                       for n in dir(methods)))
-        elif isinstance(methods, list):
-            for m in methods:
-                self._load_ui_methods(m)
-        else:
-            for name, fn in methods.items():
-                if not name.startswith("_") and hasattr(fn, "__call__") \
-                        and name[0].lower() == name[0]:
-                    self.ui_methods[name] = fn
-
-    def _load_ui_modules(self, modules):
-        if isinstance(modules, types.ModuleType):
-            self._load_ui_modules(dict((n, getattr(modules, n))
-                                       for n in dir(modules)))
-        elif isinstance(modules, list):
-            for m in modules:
-                self._load_ui_modules(m)
-        else:
-            assert isinstance(modules, dict)
-            for name, cls in modules.items():
-                try:
-                    if issubclass(cls, UIModule):
-                        self.ui_modules[name] = cls
-                except TypeError:
-                    pass
-
-    def __call__(self, request):
-        # Legacy HTTPServer interface
-        dispatcher = self.find_handler(request)
-        return dispatcher.execute()
-
-    def find_handler(self, request, **kwargs):
-        route = self.default_router.find_handler(request)
-        if route is not None:
-            return route
-
-        if self.settings.get('default_handler_class'):
-            return self.get_handler_delegate(
-                request,
-                self.settings['default_handler_class'],
-                self.settings.get('default_handler_args', {}))
-
-        return self.get_handler_delegate(
-            request, ErrorHandler, {'status_code': 404})
-
-    def get_handler_delegate(self, request, target_class, target_kwargs=None,
-                             path_args=None, path_kwargs=None):
-        """Returns `~.httputil.HTTPMessageDelegate` that can serve a request
-        for application and `RequestHandler` subclass.
-
-        :arg httputil.HTTPServerRequest request: current HTTP request.
-        :arg RequestHandler target_class: a `RequestHandler` class.
-        :arg dict target_kwargs: keyword arguments for ``target_class`` constructor.
-        :arg list path_args: positional arguments for ``target_class`` HTTP method that
-            will be executed while handling a request (``get``, ``post`` or any other).
-        :arg dict path_kwargs: keyword arguments for ``target_class`` HTTP method.
-        """
-        return _HandlerDelegate(
-            self, request, target_class, target_kwargs, path_args, path_kwargs)
-
-    def reverse_url(self, name, *args):
-        """Returns a URL path for handler named ``name``
-
-        The handler must be added to the application as a named `URLSpec`.
-
-        Args will be substituted for capturing groups in the `URLSpec` regex.
-        They will be converted to strings if necessary, encoded as utf8,
-        and url-escaped.
-        """
-        reversed_url = self.default_router.reverse_url(name, *args)
-        if reversed_url is not None:
-            return reversed_url
-
-        raise KeyError("%s not found in named urls" % name)
-
-    def log_request(self, handler):
-        """Writes a completed HTTP request to the logs.
-
-        By default writes to the python root logger.  To change
-        this behavior either subclass Application and override this method,
-        or pass a function in the application settings dictionary as
-        ``log_function``.
-        """
-        if "log_function" in self.settings:
-            self.settings["log_function"](handler)
-            return
-        if handler.get_status() < 400:
-            log_method = access_log.info
-        elif handler.get_status() < 500:
-            log_method = access_log.warning
-        else:
-            log_method = access_log.error
-        request_time = 1000.0 * handler.request.request_time()
-        log_method("%d %s %.2fms", handler.get_status(),
-                   handler._request_summary(), request_time)
-
-
-class _HandlerDelegate(httputil.HTTPMessageDelegate):
-    def __init__(self, application, request, handler_class, handler_kwargs,
-                 path_args, path_kwargs):
-        self.application = application
-        self.connection = request.connection
-        self.request = request
-        self.handler_class = handler_class
-        self.handler_kwargs = handler_kwargs or {}
-        self.path_args = path_args or []
-        self.path_kwargs = path_kwargs or {}
-        self.chunks = []
-        self.stream_request_body = _has_stream_request_body(self.handler_class)
-
-    def headers_received(self, start_line, headers):
-        if self.stream_request_body:
-            self.request.body = Future()
-            return self.execute()
-
-    def data_received(self, data):
-        if self.stream_request_body:
-            return self.handler.data_received(data)
-        else:
-            self.chunks.append(data)
-
-    def finish(self):
-        if self.stream_request_body:
-            self.request.body.set_result(None)
-        else:
-            self.request.body = b''.join(self.chunks)
-            self.request._parse_body()
-            self.execute()
-
-    def on_connection_close(self):
-        if self.stream_request_body:
-            self.handler.on_connection_close()
-        else:
-            self.chunks = None
-
-    def execute(self):
-        # If template cache is disabled (usually in the debug mode),
-        # re-compile templates and reload static files on every
-        # request so you don't need to restart to see changes
-        if not self.application.settings.get("compiled_template_cache", True):
-            with RequestHandler._template_loader_lock:
-                for loader in RequestHandler._template_loaders.values():
-                    loader.reset()
-        if not self.application.settings.get('static_hash_cache', True):
-            StaticFileHandler.reset()
-
-        self.handler = self.handler_class(self.application, self.request,
-                                          **self.handler_kwargs)
-        transforms = [t(self.request) for t in self.application.transforms]
-
-        if self.stream_request_body:
-            self.handler._prepared_future = Future()
-        # Note that if an exception escapes handler._execute it will be
-        # trapped in the Future it returns (which we are ignoring here,
-        # leaving it to be logged when the Future is GC'd).
-        # However, that shouldn't happen because _execute has a blanket
-        # except handler, and we cannot easily access the IOLoop here to
-        # call add_future (because of the requirement to remain compatible
-        # with WSGI)
-        self.handler._execute(transforms, *self.path_args,
-                              **self.path_kwargs)
-        # If we are streaming the request body, then execute() is finished
-        # when the handler has prepared to receive the body.  If not,
-        # it doesn't matter when execute() finishes (so we return None)
-        return self.handler._prepared_future
-
-
-class HTTPError(Exception):
-    """An exception that will turn into an HTTP error response.
-
-    Raising an `HTTPError` is a convenient alternative to calling
-    `RequestHandler.send_error` since it automatically ends the
-    current function.
-
-    To customize the response sent with an `HTTPError`, override
-    `RequestHandler.write_error`.
-
-    :arg int status_code: HTTP status code.  Must be listed in
-        `httplib.responses <http.client.responses>` unless the ``reason``
-        keyword argument is given.
-    :arg string log_message: Message to be written to the log for this error
-        (will not be shown to the user unless the `Application` is in debug
-        mode).  May contain ``%s``-style placeholders, which will be filled
-        in with remaining positional parameters.
-    :arg string reason: Keyword-only argument.  The HTTP "reason" phrase
-        to pass in the status line along with ``status_code``.  Normally
-        determined automatically from ``status_code``, but can be used
-        to use a non-standard numeric code.
-    """
-    def __init__(self, status_code=500, log_message=None, *args, **kwargs):
-        self.status_code = status_code
-        self.log_message = log_message
-        self.args = args
-        self.reason = kwargs.get('reason', None)
-        if log_message and not args:
-            self.log_message = log_message.replace('%', '%%')
-
-    def __str__(self):
-        message = "HTTP %d: %s" % (
-            self.status_code,
-            self.reason or httputil.responses.get(self.status_code, 'Unknown'))
-        if self.log_message:
-            return message + " (" + (self.log_message % self.args) + ")"
-        else:
-            return message
-
-
-class Finish(Exception):
-    """An exception that ends the request without producing an error response.
-
-    When `Finish` is raised in a `RequestHandler`, the request will
-    end (calling `RequestHandler.finish` if it hasn't already been
-    called), but the error-handling methods (including
-    `RequestHandler.write_error`) will not be called.
-
-    If `Finish()` was created with no arguments, the pending response
-    will be sent as-is. If `Finish()` was given an argument, that
-    argument will be passed to `RequestHandler.finish()`.
-
-    This can be a more convenient way to implement custom error pages
-    than overriding ``write_error`` (especially in library code)::
-
-        if self.current_user is None:
-            self.set_status(401)
-            self.set_header('WWW-Authenticate', 'Basic realm="something"')
-            raise Finish()
-
-    .. versionchanged:: 4.3
-       Arguments passed to ``Finish()`` will be passed on to
-       `RequestHandler.finish`.
-    """
-    pass
-
-
-class MissingArgumentError(HTTPError):
-    """Exception raised by `RequestHandler.get_argument`.
-
-    This is a subclass of `HTTPError`, so if it is uncaught a 400 response
-    code will be used instead of 500 (and a stack trace will not be logged).
-
-    .. versionadded:: 3.1
-    """
-    def __init__(self, arg_name):
-        super(MissingArgumentError, self).__init__(
-            400, 'Missing argument %s' % arg_name)
-        self.arg_name = arg_name
-
-
-class ErrorHandler(RequestHandler):
-    """Generates an error response with ``status_code`` for all requests."""
-    def initialize(self, status_code):
-        self.set_status(status_code)
-
-    def prepare(self):
-        raise HTTPError(self._status_code)
-
-    def check_xsrf_cookie(self):
-        # POSTs to an ErrorHandler don't actually have side effects,
-        # so we don't need to check the xsrf token.  This allows POSTs
-        # to the wrong url to return a 404 instead of 403.
-        pass
-
-
-class RedirectHandler(RequestHandler):
-    """Redirects the client to the given URL for all GET requests.
-
-    You should provide the keyword argument ``url`` to the handler, e.g.::
-
-        application = web.Application([
-            (r"/oldpath", web.RedirectHandler, {"url": "/newpath"}),
-        ])
-
-    `RedirectHandler` supports regular expression substitutions. E.g., to
-    swap the first and second parts of a path while preserving the remainder::
-
-        application = web.Application([
-            (r"/(.*?)/(.*?)/(.*)", web.RedirectHandler, {"url": "/{1}/{0}/{2}"}),
-        ])
-
-    The final URL is formatted with `str.format` and the substrings that match
-    the capturing groups. In the above example, a request to "/a/b/c" would be
-    formatted like::
-
-        str.format("/{1}/{0}/{2}", "a", "b", "c")  # -> "/b/a/c"
-
-    Use Python's :ref:`format string syntax <formatstrings>` to customize how
-    values are substituted.
-
-    .. versionchanged:: 4.5
-       Added support for substitutions into the destination URL.
-    """
-    def initialize(self, url, permanent=True):
-        self._url = url
-        self._permanent = permanent
-
-    def get(self, *args):
-        self.redirect(self._url.format(*args), permanent=self._permanent)
-
-
-class StaticFileHandler(RequestHandler):
-    """A simple handler that can serve static content from a directory.
-
-    A `StaticFileHandler` is configured automatically if you pass the
-    ``static_path`` keyword argument to `Application`.  This handler
-    can be customized with the ``static_url_prefix``, ``static_handler_class``,
-    and ``static_handler_args`` settings.
-
-    To map an additional path to this handler for a static data directory
-    you would add a line to your application like::
-
-        application = web.Application([
-            (r"/content/(.*)", web.StaticFileHandler, {"path": "/var/www"}),
-        ])
-
-    The handler constructor requires a ``path`` argument, which specifies the
-    local root directory of the content to be served.
-
-    Note that a capture group in the regex is required to parse the value for
-    the ``path`` argument to the get() method (different than the constructor
-    argument above); see `URLSpec` for details.
-
-    To serve a file like ``index.html`` automatically when a directory is
-    requested, set ``static_handler_args=dict(default_filename="index.html")``
-    in your application settings, or add ``default_filename`` as an initializer
-    argument for your ``StaticFileHandler``.
-
-    To maximize the effectiveness of browser caching, this class supports
-    versioned urls (by default using the argument ``?v=``).  If a version
-    is given, we instruct the browser to cache this file indefinitely.
-    `make_static_url` (also available as `RequestHandler.static_url`) can
-    be used to construct a versioned url.
-
-    This handler is intended primarily for use in development and light-duty
-    file serving; for heavy traffic it will be more efficient to use
-    a dedicated static file server (such as nginx or Apache).  We support
-    the HTTP ``Accept-Ranges`` mechanism to return partial content (because
-    some browsers require this functionality to be present to seek in
-    HTML5 audio or video).
-
-    **Subclassing notes**
-
-    This class is designed to be extensible by subclassing, but because
-    of the way static urls are generated with class methods rather than
-    instance methods, the inheritance patterns are somewhat unusual.
-    Be sure to use the ``@classmethod`` decorator when overriding a
-    class method.  Instance methods may use the attributes ``self.path``
-    ``self.absolute_path``, and ``self.modified``.
-
-    Subclasses should only override methods discussed in this section;
-    overriding other methods is error-prone.  Overriding
-    ``StaticFileHandler.get`` is particularly problematic due to the
-    tight coupling with ``compute_etag`` and other methods.
-
-    To change the way static urls are generated (e.g. to match the behavior
-    of another server or CDN), override `make_static_url`, `parse_url_path`,
-    `get_cache_time`, and/or `get_version`.
-
-    To replace all interaction with the filesystem (e.g. to serve
-    static content from a database), override `get_content`,
-    `get_content_size`, `get_modified_time`, `get_absolute_path`, and
-    `validate_absolute_path`.
-
-    .. versionchanged:: 3.1
-       Many of the methods for subclasses were added in Tornado 3.1.
-    """
-    CACHE_MAX_AGE = 86400 * 365 * 10  # 10 years
-
-    _static_hashes = {}  # type: typing.Dict
-    _lock = threading.Lock()  # protects _static_hashes
-
-    def initialize(self, path, default_filename=None):
-        self.root = path
-        self.default_filename = default_filename
-
-    @classmethod
-    def reset(cls):
-        with cls._lock:
-            cls._static_hashes = {}
-
-    def head(self, path):
-        return self.get(path, include_body=False)
-
-    @gen.coroutine
-    def get(self, path, include_body=True):
-        # Set up our path instance variables.
-        self.path = self.parse_url_path(path)
-        del path  # make sure we don't refer to path instead of self.path again
-        absolute_path = self.get_absolute_path(self.root, self.path)
-        self.absolute_path = self.validate_absolute_path(
-            self.root, absolute_path)
-        if self.absolute_path is None:
-            return
-
-        self.modified = self.get_modified_time()
-        self.set_headers()
-
-        if self.should_return_304():
-            self.set_status(304)
-            return
-
-        request_range = None
-        range_header = self.request.headers.get("Range")
-        if range_header:
-            # As per RFC 2616 14.16, if an invalid Range header is specified,
-            # the request will be treated as if the header didn't exist.
-            request_range = httputil._parse_request_range(range_header)
-
-        size = self.get_content_size()
-        if request_range:
-            start, end = request_range
-            if (start is not None and start >= size) or end == 0:
-                # As per RFC 2616 14.35.1, a range is not satisfiable only: if
-                # the first requested byte is equal to or greater than the
-                # content, or when a suffix with length 0 is specified
-                self.set_status(416)  # Range Not Satisfiable
-                self.set_header("Content-Type", "text/plain")
-                self.set_header("Content-Range", "bytes */%s" % (size, ))
-                return
-            if start is not None and start < 0:
-                start += size
-            if end is not None and end > size:
-                # Clients sometimes blindly use a large range to limit their
-                # download size; cap the endpoint at the actual file size.
-                end = size
-            # Note: only return HTTP 206 if less than the entire range has been
-            # requested. Not only is this semantically correct, but Chrome
-            # refuses to play audio if it gets an HTTP 206 in response to
-            # ``Range: bytes=0-``.
-            if size != (end or size) - (start or 0):
-                self.set_status(206)  # Partial Content
-                self.set_header("Content-Range",
-                                httputil._get_content_range(start, end, size))
-        else:
-            start = end = None
-
-        if start is not None and end is not None:
-            content_length = end - start
-        elif end is not None:
-            content_length = end
-        elif start is not None:
-            content_length = size - start
-        else:
-            content_length = size
-        self.set_header("Content-Length", content_length)
-
-        if include_body:
-            content = self.get_content(self.absolute_path, start, end)
-            if isinstance(content, bytes):
-                content = [content]
-            for chunk in content:
-                try:
-                    self.write(chunk)
-                    yield self.flush()
-                except iostream.StreamClosedError:
-                    return
-        else:
-            assert self.request.method == "HEAD"
-
-    def compute_etag(self):
-        """Sets the ``Etag`` header based on static url version.
-
-        This allows efficient ``If-None-Match`` checks against cached
-        versions, and sends the correct ``Etag`` for a partial response
-        (i.e. the same ``Etag`` as the full file).
-
-        .. versionadded:: 3.1
-        """
-        version_hash = self._get_cached_version(self.absolute_path)
-        if not version_hash:
-            return None
-        return '"%s"' % (version_hash, )
-
-    def set_headers(self):
-        """Sets the content and caching headers on the response.
-
-        .. versionadded:: 3.1
-        """
-        self.set_header("Accept-Ranges", "bytes")
-        self.set_etag_header()
-
-        if self.modified is not None:
-            self.set_header("Last-Modified", self.modified)
-
-        content_type = self.get_content_type()
-        if content_type:
-            self.set_header("Content-Type", content_type)
-
-        cache_time = self.get_cache_time(self.path, self.modified,
-                                         content_type)
-        if cache_time > 0:
-            self.set_header("Expires", datetime.datetime.utcnow() +
-                            datetime.timedelta(seconds=cache_time))
-            self.set_header("Cache-Control", "max-age=" + str(cache_time))
-
-        self.set_extra_headers(self.path)
-
-    def should_return_304(self):
-        """Returns True if the headers indicate that we should return 304.
-
-        .. versionadded:: 3.1
-        """
-        if self.check_etag_header():
-            return True
-
-        # Check the If-Modified-Since, and don't send the result if the
-        # content has not been modified
-        ims_value = self.request.headers.get("If-Modified-Since")
-        if ims_value is not None:
-            date_tuple = email.utils.parsedate(ims_value)
-            if date_tuple is not None:
-                if_since = datetime.datetime(*date_tuple[:6])
-                if if_since >= self.modified:
-                    return True
-
-        return False
-
-    @classmethod
-    def get_absolute_path(cls, root, path):
-        """Returns the absolute location of ``path`` relative to ``root``.
-
-        ``root`` is the path configured for this `StaticFileHandler`
-        (in most cases the ``static_path`` `Application` setting).
-
-        This class method may be overridden in subclasses.  By default
-        it returns a filesystem path, but other strings may be used
-        as long as they are unique and understood by the subclass's
-        overridden `get_content`.
-
-        .. versionadded:: 3.1
-        """
-        abspath = os.path.abspath(os.path.join(root, path))
-        return abspath
-
-    def validate_absolute_path(self, root, absolute_path):
-        """Validate and return the absolute path.
-
-        ``root`` is the configured path for the `StaticFileHandler`,
-        and ``path`` is the result of `get_absolute_path`
-
-        This is an instance method called during request processing,
-        so it may raise `HTTPError` or use methods like
-        `RequestHandler.redirect` (return None after redirecting to
-        halt further processing).  This is where 404 errors for missing files
-        are generated.
-
-        This method may modify the path before returning it, but note that
-        any such modifications will not be understood by `make_static_url`.
-
-        In instance methods, this method's result is available as
-        ``self.absolute_path``.
-
-        .. versionadded:: 3.1
-        """
-        # os.path.abspath strips a trailing /.
-        # We must add it back to `root` so that we only match files
-        # in a directory named `root` instead of files starting with
-        # that prefix.
-        root = os.path.abspath(root)
-        if not root.endswith(os.path.sep):
-            # abspath always removes a trailing slash, except when
-            # root is '/'. This is an unusual case, but several projects
-            # have independently discovered this technique to disable
-            # Tornado's path validation and (hopefully) do their own,
-            # so we need to support it.
-            root += os.path.sep
-        # The trailing slash also needs to be temporarily added back
-        # the requested path so a request to root/ will match.
-        if not (absolute_path + os.path.sep).startswith(root):
-            raise HTTPError(403, "%s is not in root static directory",
-                            self.path)
-        if (os.path.isdir(absolute_path) and
-                self.default_filename is not None):
-            # need to look at the request.path here for when path is empty
-            # but there is some prefix to the path that was already
-            # trimmed by the routing
-            if not self.request.path.endswith("/"):
-                self.redirect(self.request.path + "/", permanent=True)
-                return
-            absolute_path = os.path.join(absolute_path, self.default_filename)
-        if not os.path.exists(absolute_path):
-            raise HTTPError(404)
-        if not os.path.isfile(absolute_path):
-            raise HTTPError(403, "%s is not a file", self.path)
-        return absolute_path
-
-    @classmethod
-    def get_content(cls, abspath, start=None, end=None):
-        """Retrieve the content of the requested resource which is located
-        at the given absolute path.
-
-        This class method may be overridden by subclasses.  Note that its
-        signature is different from other overridable class methods
-        (no ``settings`` argument); this is deliberate to ensure that
-        ``abspath`` is able to stand on its own as a cache key.
-
-        This method should either return a byte string or an iterator
-        of byte strings.  The latter is preferred for large files
-        as it helps reduce memory fragmentation.
-
-        .. versionadded:: 3.1
-        """
-        with open(abspath, "rb") as file:
-            if start is not None:
-                file.seek(start)
-            if end is not None:
-                remaining = end - (start or 0)
-            else:
-                remaining = None
-            while True:
-                chunk_size = 64 * 1024
-                if remaining is not None and remaining < chunk_size:
-                    chunk_size = remaining
-                chunk = file.read(chunk_size)
-                if chunk:
-                    if remaining is not None:
-                        remaining -= len(chunk)
-                    yield chunk
-                else:
-                    if remaining is not None:
-                        assert remaining == 0
-                    return
-
-    @classmethod
-    def get_content_version(cls, abspath):
-        """Returns a version string for the resource at the given path.
-
-        This class method may be overridden by subclasses.  The
-        default implementation is a hash of the file's contents.
-
-        .. versionadded:: 3.1
-        """
-        data = cls.get_content(abspath)
-        hasher = hashlib.md5()
-        if isinstance(data, bytes):
-            hasher.update(data)
-        else:
-            for chunk in data:
-                hasher.update(chunk)
-        return hasher.hexdigest()
-
-    def _stat(self):
-        if not hasattr(self, '_stat_result'):
-            self._stat_result = os.stat(self.absolute_path)
-        return self._stat_result
-
-    def get_content_size(self):
-        """Retrieve the total size of the resource at the given path.
-
-        This method may be overridden by subclasses.
-
-        .. versionadded:: 3.1
-
-        .. versionchanged:: 4.0
-           This method is now always called, instead of only when
-           partial results are requested.
-        """
-        stat_result = self._stat()
-        return stat_result[stat.ST_SIZE]
-
-    def get_modified_time(self):
-        """Returns the time that ``self.absolute_path`` was last modified.
-
-        May be overridden in subclasses.  Should return a `~datetime.datetime`
-        object or None.
-
-        .. versionadded:: 3.1
-        """
-        stat_result = self._stat()
-        modified = datetime.datetime.utcfromtimestamp(
-            stat_result[stat.ST_MTIME])
-        return modified
-
-    def get_content_type(self):
-        """Returns the ``Content-Type`` header to be used for this request.
-
-        .. versionadded:: 3.1
-        """
-        mime_type, encoding = mimetypes.guess_type(self.absolute_path)
-        # per RFC 6713, use the appropriate type for a gzip compressed file
-        if encoding == "gzip":
-            return "application/gzip"
-        # As of 2015-07-21 there is no bzip2 encoding defined at
-        # http://www.iana.org/assignments/media-types/media-types.xhtml
-        # So for that (and any other encoding), use octet-stream.
-        elif encoding is not None:
-            return "application/octet-stream"
-        elif mime_type is not None:
-            return mime_type
-        # if mime_type not detected, use application/octet-stream
-        else:
-            return "application/octet-stream"
-
-    def set_extra_headers(self, path):
-        """For subclass to add extra headers to the response"""
-        pass
-
-    def get_cache_time(self, path, modified, mime_type):
-        """Override to customize cache control behavior.
-
-        Return a positive number of seconds to make the result
-        cacheable for that amount of time or 0 to mark resource as
-        cacheable for an unspecified amount of time (subject to
-        browser heuristics).
-
-        By default returns cache expiry of 10 years for resources requested
-        with ``v`` argument.
-        """
-        return self.CACHE_MAX_AGE if "v" in self.request.arguments else 0
-
-    @classmethod
-    def make_static_url(cls, settings, path, include_version=True):
-        """Constructs a versioned url for the given path.
-
-        This method may be overridden in subclasses (but note that it
-        is a class method rather than an instance method).  Subclasses
-        are only required to implement the signature
-        ``make_static_url(cls, settings, path)``; other keyword
-        arguments may be passed through `~RequestHandler.static_url`
-        but are not standard.
-
-        ``settings`` is the `Application.settings` dictionary.  ``path``
-        is the static path being requested.  The url returned should be
-        relative to the current host.
-
-        ``include_version`` determines whether the generated URL should
-        include the query string containing the version hash of the
-        file corresponding to the given ``path``.
-
-        """
-        url = settings.get('static_url_prefix', '/static/') + path
-        if not include_version:
-            return url
-
-        version_hash = cls.get_version(settings, path)
-        if not version_hash:
-            return url
-
-        return '%s?v=%s' % (url, version_hash)
-
-    def parse_url_path(self, url_path):
-        """Converts a static URL path into a filesystem path.
-
-        ``url_path`` is the path component of the URL with
-        ``static_url_prefix`` removed.  The return value should be
-        filesystem path relative to ``static_path``.
-
-        This is the inverse of `make_static_url`.
-        """
-        if os.path.sep != "/":
-            url_path = url_path.replace("/", os.path.sep)
-        return url_path
-
-    @classmethod
-    def get_version(cls, settings, path):
-        """Generate the version string to be used in static URLs.
-
-        ``settings`` is the `Application.settings` dictionary and ``path``
-        is the relative location of the requested asset on the filesystem.
-        The returned value should be a string, or ``None`` if no version
-        could be determined.
-
-        .. versionchanged:: 3.1
-           This method was previously recommended for subclasses to override;
-           `get_content_version` is now preferred as it allows the base
-           class to handle caching of the result.
-        """
-        abs_path = cls.get_absolute_path(settings['static_path'], path)
-        return cls._get_cached_version(abs_path)
-
-    @classmethod
-    def _get_cached_version(cls, abs_path):
-        with cls._lock:
-            hashes = cls._static_hashes
-            if abs_path not in hashes:
-                try:
-                    hashes[abs_path] = cls.get_content_version(abs_path)
-                except Exception:
-                    gen_log.error("Could not open static file %r", abs_path)
-                    hashes[abs_path] = None
-            hsh = hashes.get(abs_path)
-            if hsh:
-                return hsh
-        return None
-
-
-class FallbackHandler(RequestHandler):
-    """A `RequestHandler` that wraps another HTTP server callback.
-
-    The fallback is a callable object that accepts an
-    `~.httputil.HTTPServerRequest`, such as an `Application` or
-    `tornado.wsgi.WSGIContainer`.  This is most useful to use both
-    Tornado ``RequestHandlers`` and WSGI in the same server.  Typical
-    usage::
-
-        wsgi_app = tornado.wsgi.WSGIContainer(
-            django.core.handlers.wsgi.WSGIHandler())
-        application = tornado.web.Application([
-            (r"/foo", FooHandler),
-            (r".*", FallbackHandler, dict(fallback=wsgi_app),
-        ])
-    """
-    def initialize(self, fallback):
-        self.fallback = fallback
-
-    def prepare(self):
-        self.fallback(self.request)
-        self._finished = True
-
-
-class OutputTransform(object):
-    """A transform modifies the result of an HTTP request (e.g., GZip encoding)
-
-    Applications are not expected to create their own OutputTransforms
-    or interact with them directly; the framework chooses which transforms
-    (if any) to apply.
-    """
-    def __init__(self, request):
-        pass
-
-    def transform_first_chunk(self, status_code, headers, chunk, finishing):
-        # type: (int, httputil.HTTPHeaders, bytes, bool) -> typing.Tuple[int, httputil.HTTPHeaders, bytes]
-        return status_code, headers, chunk
-
-    def transform_chunk(self, chunk, finishing):
-        return chunk
-
-
-class GZipContentEncoding(OutputTransform):
-    """Applies the gzip content encoding to the response.
-
-    See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.11
-
-    .. versionchanged:: 4.0
-        Now compresses all mime types beginning with ``text/``, instead
-        of just a whitelist. (the whitelist is still used for certain
-        non-text mime types).
-    """
-    # Whitelist of compressible mime types (in addition to any types
-    # beginning with "text/").
-    CONTENT_TYPES = set(["application/javascript", "application/x-javascript",
-                         "application/xml", "application/atom+xml",
-                         "application/json", "application/xhtml+xml",
-                         "image/svg+xml"])
-    # Python's GzipFile defaults to level 9, while most other gzip
-    # tools (including gzip itself) default to 6, which is probably a
-    # better CPU/size tradeoff.
-    GZIP_LEVEL = 6
-    # Responses that are too short are unlikely to benefit from gzipping
-    # after considering the "Content-Encoding: gzip" header and the header
-    # inside the gzip encoding.
-    # Note that responses written in multiple chunks will be compressed
-    # regardless of size.
-    MIN_LENGTH = 1024
-
-    def __init__(self, request):
-        self._gzipping = "gzip" in request.headers.get("Accept-Encoding", "")
-
-    def _compressible_type(self, ctype):
-        return ctype.startswith('text/') or ctype in self.CONTENT_TYPES
-
-    def transform_first_chunk(self, status_code, headers, chunk, finishing):
-        # type: (int, httputil.HTTPHeaders, bytes, bool) -> typing.Tuple[int, httputil.HTTPHeaders, bytes]
-        # TODO: can/should this type be inherited from the superclass?
-        if 'Vary' in headers:
-            headers['Vary'] += ', Accept-Encoding'
-        else:
-            headers['Vary'] = 'Accept-Encoding'
-        if self._gzipping:
-            ctype = _unicode(headers.get("Content-Type", "")).split(";")[0]
-            self._gzipping = self._compressible_type(ctype) and \
-                (not finishing or len(chunk) >= self.MIN_LENGTH) and \
-                ("Content-Encoding" not in headers)
-        if self._gzipping:
-            headers["Content-Encoding"] = "gzip"
-            self._gzip_value = BytesIO()
-            self._gzip_file = gzip.GzipFile(mode="w", fileobj=self._gzip_value,
-                                            compresslevel=self.GZIP_LEVEL)
-            chunk = self.transform_chunk(chunk, finishing)
-            if "Content-Length" in headers:
-                # The original content length is no longer correct.
-                # If this is the last (and only) chunk, we can set the new
-                # content-length; otherwise we remove it and fall back to
-                # chunked encoding.
-                if finishing:
-                    headers["Content-Length"] = str(len(chunk))
-                else:
-                    del headers["Content-Length"]
-        return status_code, headers, chunk
-
-    def transform_chunk(self, chunk, finishing):
-        if self._gzipping:
-            self._gzip_file.write(chunk)
-            if finishing:
-                self._gzip_file.close()
-            else:
-                self._gzip_file.flush()
-            chunk = self._gzip_value.getvalue()
-            self._gzip_value.truncate(0)
-            self._gzip_value.seek(0)
-        return chunk
-
-
-def authenticated(method):
-    """Decorate methods with this to require that the user be logged in.
-
-    If the user is not logged in, they will be redirected to the configured
-    `login url <RequestHandler.get_login_url>`.
-
-    If you configure a login url with a query parameter, Tornado will
-    assume you know what you're doing and use it as-is.  If not, it
-    will add a `next` parameter so the login page knows where to send
-    you once you're logged in.
-    """
-    @functools.wraps(method)
-    def wrapper(self, *args, **kwargs):
-        if not self.current_user:
-            if self.request.method in ("GET", "HEAD"):
-                url = self.get_login_url()
-                if "?" not in url:
-                    if urlparse.urlsplit(url).scheme:
-                        # if login url is absolute, make next absolute too
-                        next_url = self.request.full_url()
-                    else:
-                        next_url = self.request.uri
-                    url += "?" + urlencode(dict(next=next_url))
-                self.redirect(url)
-                return
-            raise HTTPError(403)
-        return method(self, *args, **kwargs)
-    return wrapper
-
-
-class UIModule(object):
-    """A re-usable, modular UI unit on a page.
-
-    UI modules often execute additional queries, and they can include
-    additional CSS and JavaScript that will be included in the output
-    page, which is automatically inserted on page render.
-
-    Subclasses of UIModule must override the `render` method.
-    """
-    def __init__(self, handler):
-        self.handler = handler
-        self.request = handler.request
-        self.ui = handler.ui
-        self.locale = handler.locale
-
-    @property
-    def current_user(self):
-        return self.handler.current_user
-
-    def render(self, *args, **kwargs):
-        """Override in subclasses to return this module's output."""
-        raise NotImplementedError()
-
-    def embedded_javascript(self):
-        """Override to return a JavaScript string
-        to be embedded in the page."""
-        return None
-
-    def javascript_files(self):
-        """Override to return a list of JavaScript files needed by this module.
-
-        If the return values are relative paths, they will be passed to
-        `RequestHandler.static_url`; otherwise they will be used as-is.
-        """
-        return None
-
-    def embedded_css(self):
-        """Override to return a CSS string
-        that will be embedded in the page."""
-        return None
-
-    def css_files(self):
-        """Override to returns a list of CSS files required by this module.
-
-        If the return values are relative paths, they will be passed to
-        `RequestHandler.static_url`; otherwise they will be used as-is.
-        """
-        return None
-
-    def html_head(self):
-        """Override to return an HTML string that will be put in the <head/>
-        element.
-        """
-        return None
-
-    def html_body(self):
-        """Override to return an HTML string that will be put at the end of
-        the <body/> element.
-        """
-        return None
-
-    def render_string(self, path, **kwargs):
-        """Renders a template and returns it as a string."""
-        return self.handler.render_string(path, **kwargs)
-
-
-class _linkify(UIModule):
-    def render(self, text, **kwargs):
-        return escape.linkify(text, **kwargs)
-
-
-class _xsrf_form_html(UIModule):
-    def render(self):
-        return self.handler.xsrf_form_html()
-
-
-class TemplateModule(UIModule):
-    """UIModule that simply renders the given template.
-
-    {% module Template("foo.html") %} is similar to {% include "foo.html" %},
-    but the module version gets its own namespace (with kwargs passed to
-    Template()) instead of inheriting the outer template's namespace.
-
-    Templates rendered through this module also get access to UIModule's
-    automatic javascript/css features.  Simply call set_resources
-    inside the template and give it keyword arguments corresponding to
-    the methods on UIModule: {{ set_resources(js_files=static_url("my.js")) }}
-    Note that these resources are output once per template file, not once
-    per instantiation of the template, so they must not depend on
-    any arguments to the template.
-    """
-    def __init__(self, handler):
-        super(TemplateModule, self).__init__(handler)
-        # keep resources in both a list and a dict to preserve order
-        self._resource_list = []
-        self._resource_dict = {}
-
-    def render(self, path, **kwargs):
-        def set_resources(**kwargs):
-            if path not in self._resource_dict:
-                self._resource_list.append(kwargs)
-                self._resource_dict[path] = kwargs
-            else:
-                if self._resource_dict[path] != kwargs:
-                    raise ValueError("set_resources called with different "
-                                     "resources for the same template")
-            return ""
-        return self.render_string(path, set_resources=set_resources,
-                                  **kwargs)
-
-    def _get_resources(self, key):
-        return (r[key] for r in self._resource_list if key in r)
-
-    def embedded_javascript(self):
-        return "\n".join(self._get_resources("embedded_javascript"))
-
-    def javascript_files(self):
-        result = []
-        for f in self._get_resources("javascript_files"):
-            if isinstance(f, (unicode_type, bytes)):
-                result.append(f)
-            else:
-                result.extend(f)
-        return result
-
-    def embedded_css(self):
-        return "\n".join(self._get_resources("embedded_css"))
-
-    def css_files(self):
-        result = []
-        for f in self._get_resources("css_files"):
-            if isinstance(f, (unicode_type, bytes)):
-                result.append(f)
-            else:
-                result.extend(f)
-        return result
-
-    def html_head(self):
-        return "".join(self._get_resources("html_head"))
-
-    def html_body(self):
-        return "".join(self._get_resources("html_body"))
-
-
-class _UIModuleNamespace(object):
-    """Lazy namespace which creates UIModule proxies bound to a handler."""
-    def __init__(self, handler, ui_modules):
-        self.handler = handler
-        self.ui_modules = ui_modules
-
-    def __getitem__(self, key):
-        return self.handler._ui_module(key, self.ui_modules[key])
-
-    def __getattr__(self, key):
-        try:
-            return self[key]
-        except KeyError as e:
-            raise AttributeError(str(e))
-
-
-if hasattr(hmac, 'compare_digest'):  # python 3.3
-    _time_independent_equals = hmac.compare_digest
-else:
-    def _time_independent_equals(a, b):
-        if len(a) != len(b):
-            return False
-        result = 0
-        if isinstance(a[0], int):  # python3 byte strings
-            for x, y in zip(a, b):
-                result |= x ^ y
-        else:  # python2
-            for x, y in zip(a, b):
-                result |= ord(x) ^ ord(y)
-        return result == 0
-
-
-def create_signed_value(secret, name, value, version=None, clock=None,
-                        key_version=None):
-    if version is None:
-        version = DEFAULT_SIGNED_VALUE_VERSION
-    if clock is None:
-        clock = time.time
-
-    timestamp = utf8(str(int(clock())))
-    value = base64.b64encode(utf8(value))
-    if version == 1:
-        signature = _create_signature_v1(secret, name, value, timestamp)
-        value = b"|".join([value, timestamp, signature])
-        return value
-    elif version == 2:
-        # The v2 format consists of a version number and a series of
-        # length-prefixed fields "%d:%s", the last of which is a
-        # signature, all separated by pipes.  All numbers are in
-        # decimal format with no leading zeros.  The signature is an
-        # HMAC-SHA256 of the whole string up to that point, including
-        # the final pipe.
-        #
-        # The fields are:
-        # - format version (i.e. 2; no length prefix)
-        # - key version (integer, default is 0)
-        # - timestamp (integer seconds since epoch)
-        # - name (not encoded; assumed to be ~alphanumeric)
-        # - value (base64-encoded)
-        # - signature (hex-encoded; no length prefix)
-        def format_field(s):
-            return utf8("%d:" % len(s)) + utf8(s)
-        to_sign = b"|".join([
-            b"2",
-            format_field(str(key_version or 0)),
-            format_field(timestamp),
-            format_field(name),
-            format_field(value),
-            b''])
-
-        if isinstance(secret, dict):
-            assert key_version is not None, 'Key version must be set when sign key dict is used'
-            assert version >= 2, 'Version must be at least 2 for key version support'
-            secret = secret[key_version]
-
-        signature = _create_signature_v2(secret, to_sign)
-        return to_sign + signature
-    else:
-        raise ValueError("Unsupported version %d" % version)
-
-
-# A leading version number in decimal
-# with no leading zeros, followed by a pipe.
-_signed_value_version_re = re.compile(br"^([1-9][0-9]*)\|(.*)$")
-
-
-def _get_version(value):
-    # Figures out what version value is.  Version 1 did not include an
-    # explicit version field and started with arbitrary base64 data,
-    # which makes this tricky.
-    m = _signed_value_version_re.match(value)
-    if m is None:
-        version = 1
-    else:
-        try:
-            version = int(m.group(1))
-            if version > 999:
-                # Certain payloads from the version-less v1 format may
-                # be parsed as valid integers.  Due to base64 padding
-                # restrictions, this can only happen for numbers whose
-                # length is a multiple of 4, so we can treat all
-                # numbers up to 999 as versions, and for the rest we
-                # fall back to v1 format.
-                version = 1
-        except ValueError:
-            version = 1
-    return version
-
-
-def decode_signed_value(secret, name, value, max_age_days=31,
-                        clock=None, min_version=None):
-    if clock is None:
-        clock = time.time
-    if min_version is None:
-        min_version = DEFAULT_SIGNED_VALUE_MIN_VERSION
-    if min_version > 2:
-        raise ValueError("Unsupported min_version %d" % min_version)
-    if not value:
-        return None
-
-    value = utf8(value)
-    version = _get_version(value)
-
-    if version < min_version:
-        return None
-    if version == 1:
-        return _decode_signed_value_v1(secret, name, value,
-                                       max_age_days, clock)
-    elif version == 2:
-        return _decode_signed_value_v2(secret, name, value,
-                                       max_age_days, clock)
-    else:
-        return None
-
-
-def _decode_signed_value_v1(secret, name, value, max_age_days, clock):
-    parts = utf8(value).split(b"|")
-    if len(parts) != 3:
-        return None
-    signature = _create_signature_v1(secret, name, parts[0], parts[1])
-    if not _time_independent_equals(parts[2], signature):
-        gen_log.warning("Invalid cookie signature %r", value)
-        return None
-    timestamp = int(parts[1])
-    if timestamp < clock() - max_age_days * 86400:
-        gen_log.warning("Expired cookie %r", value)
-        return None
-    if timestamp > clock() + 31 * 86400:
-        # _cookie_signature does not hash a delimiter between the
-        # parts of the cookie, so an attacker could transfer trailing
-        # digits from the payload to the timestamp without altering the
-        # signature.  For backwards compatibility, sanity-check timestamp
-        # here instead of modifying _cookie_signature.
-        gen_log.warning("Cookie timestamp in future; possible tampering %r",
-                        value)
-        return None
-    if parts[1].startswith(b"0"):
-        gen_log.warning("Tampered cookie %r", value)
-        return None
-    try:
-        return base64.b64decode(parts[0])
-    except Exception:
-        return None
-
-
-def _decode_fields_v2(value):
-    def _consume_field(s):
-        length, _, rest = s.partition(b':')
-        n = int(length)
-        field_value = rest[:n]
-        # In python 3, indexing bytes returns small integers; we must
-        # use a slice to get a byte string as in python 2.
-        if rest[n:n + 1] != b'|':
-            raise ValueError("malformed v2 signed value field")
-        rest = rest[n + 1:]
-        return field_value, rest
-
-    rest = value[2:]  # remove version number
-    key_version, rest = _consume_field(rest)
-    timestamp, rest = _consume_field(rest)
-    name_field, rest = _consume_field(rest)
-    value_field, passed_sig = _consume_field(rest)
-    return int(key_version), timestamp, name_field, value_field, passed_sig
-
-
-def _decode_signed_value_v2(secret, name, value, max_age_days, clock):
-    try:
-        key_version, timestamp, name_field, value_field, passed_sig = _decode_fields_v2(value)
-    except ValueError:
-        return None
-    signed_string = value[:-len(passed_sig)]
-
-    if isinstance(secret, dict):
-        try:
-            secret = secret[key_version]
-        except KeyError:
-            return None
-
-    expected_sig = _create_signature_v2(secret, signed_string)
-    if not _time_independent_equals(passed_sig, expected_sig):
-        return None
-    if name_field != utf8(name):
-        return None
-    timestamp = int(timestamp)
-    if timestamp < clock() - max_age_days * 86400:
-        # The signature has expired.
-        return None
-    try:
-        return base64.b64decode(value_field)
-    except Exception:
-        return None
-
-
-def get_signature_key_version(value):
-    value = utf8(value)
-    version = _get_version(value)
-    if version < 2:
-        return None
-    try:
-        key_version, _, _, _, _ = _decode_fields_v2(value)
-    except ValueError:
-        return None
-
-    return key_version
-
-
-def _create_signature_v1(secret, *parts):
-    hash = hmac.new(utf8(secret), digestmod=hashlib.sha1)
-    for part in parts:
-        hash.update(utf8(part))
-    return utf8(hash.hexdigest())
-
-
-def _create_signature_v2(secret, s):
-    hash = hmac.new(utf8(secret), digestmod=hashlib.sha256)
-    hash.update(utf8(s))
-    return utf8(hash.hexdigest())
-
-
-def is_absolute(path):
-    return any(path.startswith(x) for x in ["/", "http:", "https:"])
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""``tornado.web`` provides a simple web framework with asynchronous 
+features that allow it to scale to large numbers of open connections, 
+making it ideal for `long polling 
+<http://en.wikipedia.org/wiki/Push_technology#Long_polling>`_. 
+ 
+Here is a simple "Hello, world" example app: 
+ 
+.. testcode:: 
+ 
+    import tornado.ioloop 
+    import tornado.web 
+ 
+    class MainHandler(tornado.web.RequestHandler): 
+        def get(self): 
+            self.write("Hello, world") 
+ 
+    if __name__ == "__main__": 
+        application = tornado.web.Application([ 
+            (r"/", MainHandler), 
+        ]) 
+        application.listen(8888) 
+        tornado.ioloop.IOLoop.current().start() 
+ 
+.. testoutput:: 
+   :hide: 
+ 
+ 
+See the :doc:`guide` for additional information. 
+ 
+Thread-safety notes 
+------------------- 
+ 
+In general, methods on `RequestHandler` and elsewhere in Tornado are 
+not thread-safe.  In particular, methods such as 
+`~RequestHandler.write()`, `~RequestHandler.finish()`, and 
+`~RequestHandler.flush()` must only be called from the main thread.  If 
+you use multiple threads it is important to use `.IOLoop.add_callback` 
+to transfer control back to the main thread before finishing the 
+request. 
+ 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import base64 
+import binascii 
+import datetime 
+import email.utils 
+import functools 
+import gzip 
+import hashlib 
+import hmac 
+import mimetypes 
+import numbers 
+import os.path 
+import re 
+import stat 
+import sys 
+import threading 
+import time 
+import tornado 
+import traceback 
+import types 
+from inspect import isclass 
+from io import BytesIO 
+ 
+from tornado.concurrent import Future 
+from tornado import escape 
+from tornado import gen 
+from tornado import httputil 
+from tornado import iostream 
+from tornado import locale 
+from tornado.log import access_log, app_log, gen_log 
+from tornado import stack_context 
+from tornado import template 
+from tornado.escape import utf8, _unicode 
+from tornado.routing import (AnyMatches, DefaultHostMatches, HostMatches, 
+                             ReversibleRouter, Rule, ReversibleRuleRouter, 
+                             URLSpec) 
+from tornado.util import (ObjectDict, raise_exc_info, 
+                          unicode_type, _websocket_mask, PY3) 
+ 
+url = URLSpec 
+ 
+if PY3: 
+    import http.cookies as Cookie 
+    import urllib.parse as urlparse 
+    from urllib.parse import urlencode 
+else: 
+    import Cookie 
+    import urlparse 
+    from urllib import urlencode 
+ 
+try: 
+    import typing  # noqa 
+ 
+    # The following types are accepted by RequestHandler.set_header 
+    # and related methods. 
+    _HeaderTypes = typing.Union[bytes, unicode_type, 
+                                numbers.Integral, datetime.datetime] 
+except ImportError: 
+    pass 
+ 
+ 
+MIN_SUPPORTED_SIGNED_VALUE_VERSION = 1 
+"""The oldest signed value version supported by this version of Tornado. 
+ 
+Signed values older than this version cannot be decoded. 
+ 
+.. versionadded:: 3.2.1 
+""" 
+ 
+MAX_SUPPORTED_SIGNED_VALUE_VERSION = 2 
+"""The newest signed value version supported by this version of Tornado. 
+ 
+Signed values newer than this version cannot be decoded. 
+ 
+.. versionadded:: 3.2.1 
+""" 
+ 
+DEFAULT_SIGNED_VALUE_VERSION = 2 
+"""The signed value version produced by `.RequestHandler.create_signed_value`. 
+ 
+May be overridden by passing a ``version`` keyword argument. 
+ 
+.. versionadded:: 3.2.1 
+""" 
+ 
+DEFAULT_SIGNED_VALUE_MIN_VERSION = 1 
+"""The oldest signed value accepted by `.RequestHandler.get_secure_cookie`. 
+ 
+May be overridden by passing a ``min_version`` keyword argument. 
+ 
+.. versionadded:: 3.2.1 
+""" 
+ 
+ 
+class RequestHandler(object): 
+    """Base class for HTTP request handlers. 
+ 
+    Subclasses must define at least one of the methods defined in the 
+    "Entry points" section below. 
+    """ 
+    SUPPORTED_METHODS = ("GET", "HEAD", "POST", "DELETE", "PATCH", "PUT", 
+                         "OPTIONS") 
+ 
+    _template_loaders = {}  # type: typing.Dict[str, template.BaseLoader] 
+    _template_loader_lock = threading.Lock() 
+    _remove_control_chars_regex = re.compile(r"[\x00-\x08\x0e-\x1f]") 
+ 
+    def __init__(self, application, request, **kwargs): 
+        super(RequestHandler, self).__init__() 
+ 
+        self.application = application 
+        self.request = request 
+        self._headers_written = False 
+        self._finished = False 
+        self._auto_finish = True 
+        self._transforms = None  # will be set in _execute 
+        self._prepared_future = None 
+        self._headers = None  # type: httputil.HTTPHeaders 
+        self.path_args = None 
+        self.path_kwargs = None 
+        self.ui = ObjectDict((n, self._ui_method(m)) for n, m in 
+                             application.ui_methods.items()) 
+        # UIModules are available as both `modules` and `_tt_modules` in the 
+        # template namespace.  Historically only `modules` was available 
+        # but could be clobbered by user additions to the namespace. 
+        # The template {% module %} directive looks in `_tt_modules` to avoid 
+        # possible conflicts. 
+        self.ui["_tt_modules"] = _UIModuleNamespace(self, 
+                                                    application.ui_modules) 
+        self.ui["modules"] = self.ui["_tt_modules"] 
+        self.clear() 
+        self.request.connection.set_close_callback(self.on_connection_close) 
+        self.initialize(**kwargs) 
+ 
+    def initialize(self): 
+        """Hook for subclass initialization. Called for each request. 
+ 
+        A dictionary passed as the third argument of a url spec will be 
+        supplied as keyword arguments to initialize(). 
+ 
+        Example:: 
+ 
+            class ProfileHandler(RequestHandler): 
+                def initialize(self, database): 
+                    self.database = database 
+ 
+                def get(self, username): 
+                    ... 
+ 
+            app = Application([ 
+                (r'/user/(.*)', ProfileHandler, dict(database=database)), 
+                ]) 
+        """ 
+        pass 
+ 
+    @property 
+    def settings(self): 
+        """An alias for `self.application.settings <Application.settings>`.""" 
+        return self.application.settings 
+ 
+    def head(self, *args, **kwargs): 
+        raise HTTPError(405) 
+ 
+    def get(self, *args, **kwargs): 
+        raise HTTPError(405) 
+ 
+    def post(self, *args, **kwargs): 
+        raise HTTPError(405) 
+ 
+    def delete(self, *args, **kwargs): 
+        raise HTTPError(405) 
+ 
+    def patch(self, *args, **kwargs): 
+        raise HTTPError(405) 
+ 
+    def put(self, *args, **kwargs): 
+        raise HTTPError(405) 
+ 
+    def options(self, *args, **kwargs): 
+        raise HTTPError(405) 
+ 
+    def prepare(self): 
+        """Called at the beginning of a request before  `get`/`post`/etc. 
+ 
+        Override this method to perform common initialization regardless 
+        of the request method. 
+ 
+        Asynchronous support: Decorate this method with `.gen.coroutine` 
+        or `.return_future` to make it asynchronous (the 
+        `asynchronous` decorator cannot be used on `prepare`). 
+        If this method returns a `.Future` execution will not proceed 
+        until the `.Future` is done. 
+ 
+        .. versionadded:: 3.1 
+           Asynchronous support. 
+        """ 
+        pass 
+ 
+    def on_finish(self): 
+        """Called after the end of a request. 
+ 
+        Override this method to perform cleanup, logging, etc. 
+        This method is a counterpart to `prepare`.  ``on_finish`` may 
+        not produce any output, as it is called after the response 
+        has been sent to the client. 
+        """ 
+        pass 
+ 
+    def on_connection_close(self): 
+        """Called in async handlers if the client closed the connection. 
+ 
+        Override this to clean up resources associated with 
+        long-lived connections.  Note that this method is called only if 
+        the connection was closed during asynchronous processing; if you 
+        need to do cleanup after every request override `on_finish` 
+        instead. 
+ 
+        Proxies may keep a connection open for a time (perhaps 
+        indefinitely) after the client has gone away, so this method 
+        may not be called promptly after the end user closes their 
+        connection. 
+        """ 
+        if _has_stream_request_body(self.__class__): 
+            if not self.request.body.done(): 
+                self.request.body.set_exception(iostream.StreamClosedError()) 
+                self.request.body.exception() 
+ 
+    def clear(self): 
+        """Resets all headers and content for this response.""" 
+        self._headers = httputil.HTTPHeaders({ 
+            "Server": "TornadoServer/%s" % tornado.version, 
+            "Content-Type": "text/html; charset=UTF-8", 
+            "Date": httputil.format_timestamp(time.time()), 
+        }) 
+        self.set_default_headers() 
+        self._write_buffer = [] 
+        self._status_code = 200 
+        self._reason = httputil.responses[200] 
+ 
+    def set_default_headers(self): 
+        """Override this to set HTTP headers at the beginning of the request. 
+ 
+        For example, this is the place to set a custom ``Server`` header. 
+        Note that setting such headers in the normal flow of request 
+        processing may not do what you want, since headers may be reset 
+        during error handling. 
+        """ 
+        pass 
+ 
+    def set_status(self, status_code, reason=None): 
+        """Sets the status code for our response. 
+ 
+        :arg int status_code: Response status code. If ``reason`` is ``None``, 
+            it must be present in `httplib.responses <http.client.responses>`. 
+        :arg string reason: Human-readable reason phrase describing the status 
+            code. If ``None``, it will be filled in from 
+            `httplib.responses <http.client.responses>`. 
+        """ 
+        self._status_code = status_code 
+        if reason is not None: 
+            self._reason = escape.native_str(reason) 
+        else: 
+            try: 
+                self._reason = httputil.responses[status_code] 
+            except KeyError: 
+                raise ValueError("unknown status code %d" % status_code) 
+ 
+    def get_status(self): 
+        """Returns the status code for our response.""" 
+        return self._status_code 
+ 
+    def set_header(self, name, value): 
+        # type: (str, _HeaderTypes) -> None 
+        """Sets the given response header name and value. 
+ 
+        If a datetime is given, we automatically format it according to the 
+        HTTP specification. If the value is not a string, we convert it to 
+        a string. All header values are then encoded as UTF-8. 
+        """ 
+        self._headers[name] = self._convert_header_value(value) 
+ 
+    def add_header(self, name, value): 
+        # type: (str, _HeaderTypes) -> None 
+        """Adds the given response header and value. 
+ 
+        Unlike `set_header`, `add_header` may be called multiple times 
+        to return multiple values for the same header. 
+        """ 
+        self._headers.add(name, self._convert_header_value(value)) 
+ 
+    def clear_header(self, name): 
+        """Clears an outgoing header, undoing a previous `set_header` call. 
+ 
+        Note that this method does not apply to multi-valued headers 
+        set by `add_header`. 
+        """ 
+        if name in self._headers: 
+            del self._headers[name] 
+ 
+    _INVALID_HEADER_CHAR_RE = re.compile(r"[\x00-\x1f]") 
+ 
+    def _convert_header_value(self, value): 
+        # type: (_HeaderTypes) -> str 
+ 
+        # Convert the input value to a str. This type check is a bit 
+        # subtle: The bytes case only executes on python 3, and the 
+        # unicode case only executes on python 2, because the other 
+        # cases are covered by the first match for str. 
+        if isinstance(value, str): 
+            retval = value 
+        elif isinstance(value, bytes):  # py3 
+            # Non-ascii characters in headers are not well supported, 
+            # but if you pass bytes, use latin1 so they pass through as-is. 
+            retval = value.decode('latin1') 
+        elif isinstance(value, unicode_type):  # py2 
+            # TODO: This is inconsistent with the use of latin1 above, 
+            # but it's been that way for a long time. Should it change? 
+            retval = escape.utf8(value) 
+        elif isinstance(value, numbers.Integral): 
+            # return immediately since we know the converted value will be safe 
+            return str(value) 
+        elif isinstance(value, datetime.datetime): 
+            return httputil.format_timestamp(value) 
+        else: 
+            raise TypeError("Unsupported header value %r" % value) 
+        # If \n is allowed into the header, it is possible to inject 
+        # additional headers or split the request. 
+        if RequestHandler._INVALID_HEADER_CHAR_RE.search(retval): 
+            raise ValueError("Unsafe header value %r", retval) 
+        return retval 
+ 
+    _ARG_DEFAULT = object() 
+ 
+    def get_argument(self, name, default=_ARG_DEFAULT, strip=True): 
+        """Returns the value of the argument with the given name. 
+ 
+        If default is not provided, the argument is considered to be 
+        required, and we raise a `MissingArgumentError` if it is missing. 
+ 
+        If the argument appears in the url more than once, we return the 
+        last value. 
+ 
+        The returned value is always unicode. 
+        """ 
+        return self._get_argument(name, default, self.request.arguments, strip) 
+ 
+    def get_arguments(self, name, strip=True): 
+        """Returns a list of the arguments with the given name. 
+ 
+        If the argument is not present, returns an empty list. 
+ 
+        The returned values are always unicode. 
+        """ 
+ 
+        # Make sure `get_arguments` isn't accidentally being called with a 
+        # positional argument that's assumed to be a default (like in 
+        # `get_argument`.) 
+        assert isinstance(strip, bool) 
+ 
+        return self._get_arguments(name, self.request.arguments, strip) 
+ 
+    def get_body_argument(self, name, default=_ARG_DEFAULT, strip=True): 
+        """Returns the value of the argument with the given name 
+        from the request body. 
+ 
+        If default is not provided, the argument is considered to be 
+        required, and we raise a `MissingArgumentError` if it is missing. 
+ 
+        If the argument appears in the url more than once, we return the 
+        last value. 
+ 
+        The returned value is always unicode. 
+ 
+        .. versionadded:: 3.2 
+        """ 
+        return self._get_argument(name, default, self.request.body_arguments, 
+                                  strip) 
+ 
+    def get_body_arguments(self, name, strip=True): 
+        """Returns a list of the body arguments with the given name. 
+ 
+        If the argument is not present, returns an empty list. 
+ 
+        The returned values are always unicode. 
+ 
+        .. versionadded:: 3.2 
+        """ 
+        return self._get_arguments(name, self.request.body_arguments, strip) 
+ 
+    def get_query_argument(self, name, default=_ARG_DEFAULT, strip=True): 
+        """Returns the value of the argument with the given name 
+        from the request query string. 
+ 
+        If default is not provided, the argument is considered to be 
+        required, and we raise a `MissingArgumentError` if it is missing. 
+ 
+        If the argument appears in the url more than once, we return the 
+        last value. 
+ 
+        The returned value is always unicode. 
+ 
+        .. versionadded:: 3.2 
+        """ 
+        return self._get_argument(name, default, 
+                                  self.request.query_arguments, strip) 
+ 
+    def get_query_arguments(self, name, strip=True): 
+        """Returns a list of the query arguments with the given name. 
+ 
+        If the argument is not present, returns an empty list. 
+ 
+        The returned values are always unicode. 
+ 
+        .. versionadded:: 3.2 
+        """ 
+        return self._get_arguments(name, self.request.query_arguments, strip) 
+ 
+    def _get_argument(self, name, default, source, strip=True): 
+        args = self._get_arguments(name, source, strip=strip) 
+        if not args: 
+            if default is self._ARG_DEFAULT: 
+                raise MissingArgumentError(name) 
+            return default 
+        return args[-1] 
+ 
+    def _get_arguments(self, name, source, strip=True): 
+        values = [] 
+        for v in source.get(name, []): 
+            v = self.decode_argument(v, name=name) 
+            if isinstance(v, unicode_type): 
+                # Get rid of any weird control chars (unless decoding gave 
+                # us bytes, in which case leave it alone) 
+                v = RequestHandler._remove_control_chars_regex.sub(" ", v) 
+            if strip: 
+                v = v.strip() 
+            values.append(v) 
+        return values 
+ 
+    def decode_argument(self, value, name=None): 
+        """Decodes an argument from the request. 
+ 
+        The argument has been percent-decoded and is now a byte string. 
+        By default, this method decodes the argument as utf-8 and returns 
+        a unicode string, but this may be overridden in subclasses. 
+ 
+        This method is used as a filter for both `get_argument()` and for 
+        values extracted from the url and passed to `get()`/`post()`/etc. 
+ 
+        The name of the argument is provided if known, but may be None 
+        (e.g. for unnamed groups in the url regex). 
+        """ 
+        try: 
+            return _unicode(value) 
+        except UnicodeDecodeError: 
+            raise HTTPError(400, "Invalid unicode in %s: %r" % 
+                            (name or "url", value[:40])) 
+ 
+    @property 
+    def cookies(self): 
+        """An alias for 
+        `self.request.cookies <.httputil.HTTPServerRequest.cookies>`.""" 
+        return self.request.cookies 
+ 
+    def get_cookie(self, name, default=None): 
+        """Gets the value of the cookie with the given name, else default.""" 
+        if self.request.cookies is not None and name in self.request.cookies: 
+            return self.request.cookies[name].value 
+        return default 
+ 
+    def set_cookie(self, name, value, domain=None, expires=None, path="/", 
+                   expires_days=None, **kwargs): 
+        """Sets the given cookie name/value with the given options. 
+ 
+        Additional keyword arguments are set on the Cookie.Morsel 
+        directly. 
+        See https://docs.python.org/2/library/cookie.html#Cookie.Morsel 
+        for available attributes. 
+        """ 
+        # The cookie library only accepts type str, in both python 2 and 3 
+        name = escape.native_str(name) 
+        value = escape.native_str(value) 
+        if re.search(r"[\x00-\x20]", name + value): 
+            # Don't let us accidentally inject bad stuff 
+            raise ValueError("Invalid cookie %r: %r" % (name, value)) 
+        if not hasattr(self, "_new_cookie"): 
+            self._new_cookie = Cookie.SimpleCookie() 
+        if name in self._new_cookie: 
+            del self._new_cookie[name] 
+        self._new_cookie[name] = value 
+        morsel = self._new_cookie[name] 
+        if domain: 
+            morsel["domain"] = domain 
+        if expires_days is not None and not expires: 
+            expires = datetime.datetime.utcnow() + datetime.timedelta( 
+                days=expires_days) 
+        if expires: 
+            morsel["expires"] = httputil.format_timestamp(expires) 
+        if path: 
+            morsel["path"] = path 
+        for k, v in kwargs.items(): 
+            if k == 'max_age': 
+                k = 'max-age' 
+ 
+            # skip falsy values for httponly and secure flags because 
+            # SimpleCookie sets them regardless 
+            if k in ['httponly', 'secure'] and not v: 
+                continue 
+ 
+            morsel[k] = v 
+ 
+    def clear_cookie(self, name, path="/", domain=None): 
+        """Deletes the cookie with the given name. 
+ 
+        Due to limitations of the cookie protocol, you must pass the same 
+        path and domain to clear a cookie as were used when that cookie 
+        was set (but there is no way to find out on the server side 
+        which values were used for a given cookie). 
+        """ 
+        expires = datetime.datetime.utcnow() - datetime.timedelta(days=365) 
+        self.set_cookie(name, value="", path=path, expires=expires, 
+                        domain=domain) 
+ 
+    def clear_all_cookies(self, path="/", domain=None): 
+        """Deletes all the cookies the user sent with this request. 
+ 
+        See `clear_cookie` for more information on the path and domain 
+        parameters. 
+ 
+        .. versionchanged:: 3.2 
+ 
+           Added the ``path`` and ``domain`` parameters. 
+        """ 
+        for name in self.request.cookies: 
+            self.clear_cookie(name, path=path, domain=domain) 
+ 
+    def set_secure_cookie(self, name, value, expires_days=30, version=None, 
+                          **kwargs): 
+        """Signs and timestamps a cookie so it cannot be forged. 
+ 
+        You must specify the ``cookie_secret`` setting in your Application 
+        to use this method. It should be a long, random sequence of bytes 
+        to be used as the HMAC secret for the signature. 
+ 
+        To read a cookie set with this method, use `get_secure_cookie()`. 
+ 
+        Note that the ``expires_days`` parameter sets the lifetime of the 
+        cookie in the browser, but is independent of the ``max_age_days`` 
+        parameter to `get_secure_cookie`. 
+ 
+        Secure cookies may contain arbitrary byte values, not just unicode 
+        strings (unlike regular cookies) 
+ 
+        .. versionchanged:: 3.2.1 
+ 
+           Added the ``version`` argument.  Introduced cookie version 2 
+           and made it the default. 
+        """ 
+        self.set_cookie(name, self.create_signed_value(name, value, 
+                                                       version=version), 
+                        expires_days=expires_days, **kwargs) 
+ 
+    def create_signed_value(self, name, value, version=None): 
+        """Signs and timestamps a string so it cannot be forged. 
+ 
+        Normally used via set_secure_cookie, but provided as a separate 
+        method for non-cookie uses.  To decode a value not stored 
+        as a cookie use the optional value argument to get_secure_cookie. 
+ 
+        .. versionchanged:: 3.2.1 
+ 
+           Added the ``version`` argument.  Introduced cookie version 2 
+           and made it the default. 
+        """ 
+        self.require_setting("cookie_secret", "secure cookies") 
+        secret = self.application.settings["cookie_secret"] 
+        key_version = None 
+        if isinstance(secret, dict): 
+            if self.application.settings.get("key_version") is None: 
+                raise Exception("key_version setting must be used for secret_key dicts") 
+            key_version = self.application.settings["key_version"] 
+ 
+        return create_signed_value(secret, name, value, version=version, 
+                                   key_version=key_version) 
+ 
+    def get_secure_cookie(self, name, value=None, max_age_days=31, 
+                          min_version=None): 
+        """Returns the given signed cookie if it validates, or None. 
+ 
+        The decoded cookie value is returned as a byte string (unlike 
+        `get_cookie`). 
+ 
+        .. versionchanged:: 3.2.1 
+ 
+           Added the ``min_version`` argument.  Introduced cookie version 2; 
+           both versions 1 and 2 are accepted by default. 
+        """ 
+        self.require_setting("cookie_secret", "secure cookies") 
+        if value is None: 
+            value = self.get_cookie(name) 
+        return decode_signed_value(self.application.settings["cookie_secret"], 
+                                   name, value, max_age_days=max_age_days, 
+                                   min_version=min_version) 
+ 
+    def get_secure_cookie_key_version(self, name, value=None): 
+        """Returns the signing key version of the secure cookie. 
+ 
+        The version is returned as int. 
+        """ 
+        self.require_setting("cookie_secret", "secure cookies") 
+        if value is None: 
+            value = self.get_cookie(name) 
+        return get_signature_key_version(value) 
+ 
+    def redirect(self, url, permanent=False, status=None): 
+        """Sends a redirect to the given (optionally relative) URL. 
+ 
+        If the ``status`` argument is specified, that value is used as the 
+        HTTP status code; otherwise either 301 (permanent) or 302 
+        (temporary) is chosen based on the ``permanent`` argument. 
+        The default is 302 (temporary). 
+        """ 
+        if self._headers_written: 
+            raise Exception("Cannot redirect after headers have been written") 
+        if status is None: 
+            status = 301 if permanent else 302 
+        else: 
+            assert isinstance(status, int) and 300 <= status <= 399 
+        self.set_status(status) 
+        self.set_header("Location", utf8(url)) 
+        self.finish() 
+ 
+    def write(self, chunk): 
+        """Writes the given chunk to the output buffer. 
+ 
+        To write the output to the network, use the flush() method below. 
+ 
+        If the given chunk is a dictionary, we write it as JSON and set 
+        the Content-Type of the response to be ``application/json``. 
+        (if you want to send JSON as a different ``Content-Type``, call 
+        set_header *after* calling write()). 
+ 
+        Note that lists are not converted to JSON because of a potential 
+        cross-site security vulnerability.  All JSON output should be 
+        wrapped in a dictionary.  More details at 
+        http://haacked.com/archive/2009/06/25/json-hijacking.aspx/ and 
+        https://github.com/facebook/tornado/issues/1009 
+        """ 
+        if self._finished: 
+            raise RuntimeError("Cannot write() after finish()") 
+        if not isinstance(chunk, (bytes, unicode_type, dict)): 
+            message = "write() only accepts bytes, unicode, and dict objects" 
+            if isinstance(chunk, list): 
+                message += ". Lists not accepted for security reasons; see http://www.tornadoweb.org/en/stable/web.html#tornado.web.RequestHandler.write" 
+            raise TypeError(message) 
+        if isinstance(chunk, dict): 
+            chunk = escape.json_encode(chunk) 
+            self.set_header("Content-Type", "application/json; charset=UTF-8") 
+        chunk = utf8(chunk) 
+        self._write_buffer.append(chunk) 
+ 
+    def render(self, template_name, **kwargs): 
+        """Renders the template with the given arguments as the response.""" 
+        if self._finished: 
+            raise RuntimeError("Cannot render() after finish()") 
+        html = self.render_string(template_name, **kwargs) 
+ 
+        # Insert the additional JS and CSS added by the modules on the page 
+        js_embed = [] 
+        js_files = [] 
+        css_embed = [] 
+        css_files = [] 
+        html_heads = [] 
+        html_bodies = [] 
+        for module in getattr(self, "_active_modules", {}).values(): 
+            embed_part = module.embedded_javascript() 
+            if embed_part: 
+                js_embed.append(utf8(embed_part)) 
+            file_part = module.javascript_files() 
+            if file_part: 
+                if isinstance(file_part, (unicode_type, bytes)): 
+                    js_files.append(file_part) 
+                else: 
+                    js_files.extend(file_part) 
+            embed_part = module.embedded_css() 
+            if embed_part: 
+                css_embed.append(utf8(embed_part)) 
+            file_part = module.css_files() 
+            if file_part: 
+                if isinstance(file_part, (unicode_type, bytes)): 
+                    css_files.append(file_part) 
+                else: 
+                    css_files.extend(file_part) 
+            head_part = module.html_head() 
+            if head_part: 
+                html_heads.append(utf8(head_part)) 
+            body_part = module.html_body() 
+            if body_part: 
+                html_bodies.append(utf8(body_part)) 
+ 
+        if js_files: 
+            # Maintain order of JavaScript files given by modules 
+            js = self.render_linked_js(js_files) 
+            sloc = html.rindex(b'</body>') 
+            html = html[:sloc] + utf8(js) + b'\n' + html[sloc:] 
+        if js_embed: 
+            js = self.render_embed_js(js_embed) 
+            sloc = html.rindex(b'</body>') 
+            html = html[:sloc] + js + b'\n' + html[sloc:] 
+        if css_files: 
+            css = self.render_linked_css(css_files) 
+            hloc = html.index(b'</head>') 
+            html = html[:hloc] + utf8(css) + b'\n' + html[hloc:] 
+        if css_embed: 
+            css = self.render_embed_css(css_embed) 
+            hloc = html.index(b'</head>') 
+            html = html[:hloc] + css + b'\n' + html[hloc:] 
+        if html_heads: 
+            hloc = html.index(b'</head>') 
+            html = html[:hloc] + b''.join(html_heads) + b'\n' + html[hloc:] 
+        if html_bodies: 
+            hloc = html.index(b'</body>') 
+            html = html[:hloc] + b''.join(html_bodies) + b'\n' + html[hloc:] 
+        self.finish(html) 
+ 
+    def render_linked_js(self, js_files): 
+        """Default method used to render the final js links for the 
+        rendered webpage. 
+ 
+        Override this method in a sub-classed controller to change the output. 
+        """ 
+        paths = [] 
+        unique_paths = set() 
+ 
+        for path in js_files: 
+            if not is_absolute(path): 
+                path = self.static_url(path) 
+            if path not in unique_paths: 
+                paths.append(path) 
+                unique_paths.add(path) 
+ 
+        return ''.join('<script src="' + escape.xhtml_escape(p) + 
+                       '" type="text/javascript"></script>' 
+                       for p in paths) 
+ 
+    def render_embed_js(self, js_embed): 
+        """Default method used to render the final embedded js for the 
+        rendered webpage. 
+ 
+        Override this method in a sub-classed controller to change the output. 
+        """ 
+        return b'<script type="text/javascript">\n//<![CDATA[\n' + \ 
+               b'\n'.join(js_embed) + b'\n//]]>\n</script>' 
+ 
+    def render_linked_css(self, css_files): 
+        """Default method used to render the final css links for the 
+        rendered webpage. 
+ 
+        Override this method in a sub-classed controller to change the output. 
+        """ 
+        paths = [] 
+        unique_paths = set() 
+ 
+        for path in css_files: 
+            if not is_absolute(path): 
+                path = self.static_url(path) 
+            if path not in unique_paths: 
+                paths.append(path) 
+                unique_paths.add(path) 
+ 
+        return ''.join('<link href="' + escape.xhtml_escape(p) + '" ' 
+                       'type="text/css" rel="stylesheet"/>' 
+                       for p in paths) 
+ 
+    def render_embed_css(self, css_embed): 
+        """Default method used to render the final embedded css for the 
+        rendered webpage. 
+ 
+        Override this method in a sub-classed controller to change the output. 
+        """ 
+        return b'<style type="text/css">\n' + b'\n'.join(css_embed) + \ 
+               b'\n</style>' 
+ 
+    def render_string(self, template_name, **kwargs): 
+        """Generate the given template with the given arguments. 
+ 
+        We return the generated byte string (in utf8). To generate and 
+        write a template as a response, use render() above. 
+        """ 
+        # If no template_path is specified, use the path of the calling file 
+        template_path = self.get_template_path() 
+        if not template_path: 
+            frame = sys._getframe(0) 
+            web_file = frame.f_code.co_filename 
+            while frame.f_code.co_filename == web_file: 
+                frame = frame.f_back 
+            template_path = os.path.dirname(frame.f_code.co_filename) 
+        with RequestHandler._template_loader_lock: 
+            if template_path not in RequestHandler._template_loaders: 
+                loader = self.create_template_loader(template_path) 
+                RequestHandler._template_loaders[template_path] = loader 
+            else: 
+                loader = RequestHandler._template_loaders[template_path] 
+        t = loader.load(template_name) 
+        namespace = self.get_template_namespace() 
+        namespace.update(kwargs) 
+        return t.generate(**namespace) 
+ 
+    def get_template_namespace(self): 
+        """Returns a dictionary to be used as the default template namespace. 
+ 
+        May be overridden by subclasses to add or modify values. 
+ 
+        The results of this method will be combined with additional 
+        defaults in the `tornado.template` module and keyword arguments 
+        to `render` or `render_string`. 
+        """ 
+        namespace = dict( 
+            handler=self, 
+            request=self.request, 
+            current_user=self.current_user, 
+            locale=self.locale, 
+            _=self.locale.translate, 
+            pgettext=self.locale.pgettext, 
+            static_url=self.static_url, 
+            xsrf_form_html=self.xsrf_form_html, 
+            reverse_url=self.reverse_url 
+        ) 
+        namespace.update(self.ui) 
+        return namespace 
+ 
+    def create_template_loader(self, template_path): 
+        """Returns a new template loader for the given path. 
+ 
+        May be overridden by subclasses.  By default returns a 
+        directory-based loader on the given path, using the 
+        ``autoescape`` and ``template_whitespace`` application 
+        settings.  If a ``template_loader`` application setting is 
+        supplied, uses that instead. 
+        """ 
+        settings = self.application.settings 
+        if "template_loader" in settings: 
+            return settings["template_loader"] 
+        kwargs = {} 
+        if "autoescape" in settings: 
+            # autoescape=None means "no escaping", so we have to be sure 
+            # to only pass this kwarg if the user asked for it. 
+            kwargs["autoescape"] = settings["autoescape"] 
+        if "template_whitespace" in settings: 
+            kwargs["whitespace"] = settings["template_whitespace"] 
+        return template.Loader(template_path, **kwargs) 
+ 
+    def flush(self, include_footers=False, callback=None): 
+        """Flushes the current output buffer to the network. 
+ 
+        The ``callback`` argument, if given, can be used for flow control: 
+        it will be run when all flushed data has been written to the socket. 
+        Note that only one flush callback can be outstanding at a time; 
+        if another flush occurs before the previous flush's callback 
+        has been run, the previous callback will be discarded. 
+ 
+        .. versionchanged:: 4.0 
+           Now returns a `.Future` if no callback is given. 
+        """ 
+        chunk = b"".join(self._write_buffer) 
+        self._write_buffer = [] 
+        if not self._headers_written: 
+            self._headers_written = True 
+            for transform in self._transforms: 
+                self._status_code, self._headers, chunk = \ 
+                    transform.transform_first_chunk( 
+                        self._status_code, self._headers, 
+                        chunk, include_footers) 
+            # Ignore the chunk and only write the headers for HEAD requests 
+            if self.request.method == "HEAD": 
+                chunk = None 
+ 
+            # Finalize the cookie headers (which have been stored in a side 
+            # object so an outgoing cookie could be overwritten before it 
+            # is sent). 
+            if hasattr(self, "_new_cookie"): 
+                for cookie in self._new_cookie.values(): 
+                    self.add_header("Set-Cookie", cookie.OutputString(None)) 
+ 
+            start_line = httputil.ResponseStartLine('', 
+                                                    self._status_code, 
+                                                    self._reason) 
+            return self.request.connection.write_headers( 
+                start_line, self._headers, chunk, callback=callback) 
+        else: 
+            for transform in self._transforms: 
+                chunk = transform.transform_chunk(chunk, include_footers) 
+            # Ignore the chunk and only write the headers for HEAD requests 
+            if self.request.method != "HEAD": 
+                return self.request.connection.write(chunk, callback=callback) 
+            else: 
+                future = Future() 
+                future.set_result(None) 
+                return future 
+ 
+    def finish(self, chunk=None): 
+        """Finishes this response, ending the HTTP request.""" 
+        if self._finished: 
+            raise RuntimeError("finish() called twice") 
+ 
+        if chunk is not None: 
+            self.write(chunk) 
+ 
+        # Automatically support ETags and add the Content-Length header if 
+        # we have not flushed any content yet. 
+        if not self._headers_written: 
+            if (self._status_code == 200 and 
+                self.request.method in ("GET", "HEAD") and 
+                    "Etag" not in self._headers): 
+                self.set_etag_header() 
+                if self.check_etag_header(): 
+                    self._write_buffer = [] 
+                    self.set_status(304) 
+            if (self._status_code in (204, 304) or 
+                (self._status_code >= 100 and self._status_code < 200)): 
+                assert not self._write_buffer, "Cannot send body with %s" % self._status_code 
+                self._clear_headers_for_304() 
+            elif "Content-Length" not in self._headers: 
+                content_length = sum(len(part) for part in self._write_buffer) 
+                self.set_header("Content-Length", content_length) 
+ 
+        if hasattr(self.request, "connection"): 
+            # Now that the request is finished, clear the callback we 
+            # set on the HTTPConnection (which would otherwise prevent the 
+            # garbage collection of the RequestHandler when there 
+            # are keepalive connections) 
+            self.request.connection.set_close_callback(None) 
+ 
+        self.flush(include_footers=True) 
+        self.request.finish() 
+        self._log() 
+        self._finished = True 
+        self.on_finish() 
+        self._break_cycles() 
+ 
+    def _break_cycles(self): 
+        # Break up a reference cycle between this handler and the 
+        # _ui_module closures to allow for faster GC on CPython. 
+        self.ui = None 
+ 
+    def send_error(self, status_code=500, **kwargs): 
+        """Sends the given HTTP error code to the browser. 
+ 
+        If `flush()` has already been called, it is not possible to send 
+        an error, so this method will simply terminate the response. 
+        If output has been written but not yet flushed, it will be discarded 
+        and replaced with the error page. 
+ 
+        Override `write_error()` to customize the error page that is returned. 
+        Additional keyword arguments are passed through to `write_error`. 
+        """ 
+        if self._headers_written: 
+            gen_log.error("Cannot send error response after headers written") 
+            if not self._finished: 
+                # If we get an error between writing headers and finishing, 
+                # we are unlikely to be able to finish due to a 
+                # Content-Length mismatch. Try anyway to release the 
+                # socket. 
+                try: 
+                    self.finish() 
+                except Exception: 
+                    gen_log.error("Failed to flush partial response", 
+                                  exc_info=True) 
+            return 
+        self.clear() 
+ 
+        reason = kwargs.get('reason') 
+        if 'exc_info' in kwargs: 
+            exception = kwargs['exc_info'][1] 
+            if isinstance(exception, HTTPError) and exception.reason: 
+                reason = exception.reason 
+        self.set_status(status_code, reason=reason) 
+        try: 
+            self.write_error(status_code, **kwargs) 
+        except Exception: 
+            app_log.error("Uncaught exception in write_error", exc_info=True) 
+        if not self._finished: 
+            self.finish() 
+ 
+    def write_error(self, status_code, **kwargs): 
+        """Override to implement custom error pages. 
+ 
+        ``write_error`` may call `write`, `render`, `set_header`, etc 
+        to produce output as usual. 
+ 
+        If this error was caused by an uncaught exception (including 
+        HTTPError), an ``exc_info`` triple will be available as 
+        ``kwargs["exc_info"]``.  Note that this exception may not be 
+        the "current" exception for purposes of methods like 
+        ``sys.exc_info()`` or ``traceback.format_exc``. 
+        """ 
+        if self.settings.get("serve_traceback") and "exc_info" in kwargs: 
+            # in debug mode, try to send a traceback 
+            self.set_header('Content-Type', 'text/plain') 
+            for line in traceback.format_exception(*kwargs["exc_info"]): 
+                self.write(line) 
+            self.finish() 
+        else: 
+            self.finish("<html><title>%(code)d: %(message)s</title>" 
+                        "<body>%(code)d: %(message)s</body></html>" % { 
+                            "code": status_code, 
+                            "message": self._reason, 
+                        }) 
+ 
+    @property 
+    def locale(self): 
+        """The locale for the current session. 
+ 
+        Determined by either `get_user_locale`, which you can override to 
+        set the locale based on, e.g., a user preference stored in a 
+        database, or `get_browser_locale`, which uses the ``Accept-Language`` 
+        header. 
+ 
+        .. versionchanged: 4.1 
+           Added a property setter. 
+        """ 
+        if not hasattr(self, "_locale"): 
+            self._locale = self.get_user_locale() 
+            if not self._locale: 
+                self._locale = self.get_browser_locale() 
+                assert self._locale 
+        return self._locale 
+ 
+    @locale.setter 
+    def locale(self, value): 
+        self._locale = value 
+ 
+    def get_user_locale(self): 
+        """Override to determine the locale from the authenticated user. 
+ 
+        If None is returned, we fall back to `get_browser_locale()`. 
+ 
+        This method should return a `tornado.locale.Locale` object, 
+        most likely obtained via a call like ``tornado.locale.get("en")`` 
+        """ 
+        return None 
+ 
+    def get_browser_locale(self, default="en_US"): 
+        """Determines the user's locale from ``Accept-Language`` header. 
+ 
+        See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.4 
+        """ 
+        if "Accept-Language" in self.request.headers: 
+            languages = self.request.headers["Accept-Language"].split(",") 
+            locales = [] 
+            for language in languages: 
+                parts = language.strip().split(";") 
+                if len(parts) > 1 and parts[1].startswith("q="): 
+                    try: 
+                        score = float(parts[1][2:]) 
+                    except (ValueError, TypeError): 
+                        score = 0.0 
+                else: 
+                    score = 1.0 
+                locales.append((parts[0], score)) 
+            if locales: 
+                locales.sort(key=lambda pair: pair[1], reverse=True) 
+                codes = [l[0] for l in locales] 
+                return locale.get(*codes) 
+        return locale.get(default) 
+ 
+    @property 
+    def current_user(self): 
+        """The authenticated user for this request. 
+ 
+        This is set in one of two ways: 
+ 
+        * A subclass may override `get_current_user()`, which will be called 
+          automatically the first time ``self.current_user`` is accessed. 
+          `get_current_user()` will only be called once per request, 
+          and is cached for future access:: 
+ 
+              def get_current_user(self): 
+                  user_cookie = self.get_secure_cookie("user") 
+                  if user_cookie: 
+                      return json.loads(user_cookie) 
+                  return None 
+ 
+        * It may be set as a normal variable, typically from an overridden 
+          `prepare()`:: 
+ 
+              @gen.coroutine 
+              def prepare(self): 
+                  user_id_cookie = self.get_secure_cookie("user_id") 
+                  if user_id_cookie: 
+                      self.current_user = yield load_user(user_id_cookie) 
+ 
+        Note that `prepare()` may be a coroutine while `get_current_user()` 
+        may not, so the latter form is necessary if loading the user requires 
+        asynchronous operations. 
+ 
+        The user object may be any type of the application's choosing. 
+        """ 
+        if not hasattr(self, "_current_user"): 
+            self._current_user = self.get_current_user() 
+        return self._current_user 
+ 
+    @current_user.setter 
+    def current_user(self, value): 
+        self._current_user = value 
+ 
+    def get_current_user(self): 
+        """Override to determine the current user from, e.g., a cookie. 
+ 
+        This method may not be a coroutine. 
+        """ 
+        return None 
+ 
+    def get_login_url(self): 
+        """Override to customize the login URL based on the request. 
+ 
+        By default, we use the ``login_url`` application setting. 
+        """ 
+        self.require_setting("login_url", "@tornado.web.authenticated") 
+        return self.application.settings["login_url"] 
+ 
+    def get_template_path(self): 
+        """Override to customize template path for each handler. 
+ 
+        By default, we use the ``template_path`` application setting. 
+        Return None to load templates relative to the calling file. 
+        """ 
+        return self.application.settings.get("template_path") 
+ 
+    @property 
+    def xsrf_token(self): 
+        """The XSRF-prevention token for the current user/session. 
+ 
+        To prevent cross-site request forgery, we set an '_xsrf' cookie 
+        and include the same '_xsrf' value as an argument with all POST 
+        requests. If the two do not match, we reject the form submission 
+        as a potential forgery. 
+ 
+        See http://en.wikipedia.org/wiki/Cross-site_request_forgery 
+ 
+        .. versionchanged:: 3.2.2 
+           The xsrf token will now be have a random mask applied in every 
+           request, which makes it safe to include the token in pages 
+           that are compressed.  See http://breachattack.com for more 
+           information on the issue fixed by this change.  Old (version 1) 
+           cookies will be converted to version 2 when this method is called 
+           unless the ``xsrf_cookie_version`` `Application` setting is 
+           set to 1. 
+ 
+        .. versionchanged:: 4.3 
+           The ``xsrf_cookie_kwargs`` `Application` setting may be 
+           used to supply additional cookie options (which will be 
+           passed directly to `set_cookie`). For example, 
+           ``xsrf_cookie_kwargs=dict(httponly=True, secure=True)`` 
+           will set the ``secure`` and ``httponly`` flags on the 
+           ``_xsrf`` cookie. 
+        """ 
+        if not hasattr(self, "_xsrf_token"): 
+            version, token, timestamp = self._get_raw_xsrf_token() 
+            output_version = self.settings.get("xsrf_cookie_version", 2) 
+            cookie_kwargs = self.settings.get("xsrf_cookie_kwargs", {}) 
+            if output_version == 1: 
+                self._xsrf_token = binascii.b2a_hex(token) 
+            elif output_version == 2: 
+                mask = os.urandom(4) 
+                self._xsrf_token = b"|".join([ 
+                    b"2", 
+                    binascii.b2a_hex(mask), 
+                    binascii.b2a_hex(_websocket_mask(mask, token)), 
+                    utf8(str(int(timestamp)))]) 
+            else: 
+                raise ValueError("unknown xsrf cookie version %d", 
+                                 output_version) 
+            if version is None: 
+                expires_days = 30 if self.current_user else None 
+                self.set_cookie("_xsrf", self._xsrf_token, 
+                                expires_days=expires_days, 
+                                **cookie_kwargs) 
+        return self._xsrf_token 
+ 
+    def _get_raw_xsrf_token(self): 
+        """Read or generate the xsrf token in its raw form. 
+ 
+        The raw_xsrf_token is a tuple containing: 
+ 
+        * version: the version of the cookie from which this token was read, 
+          or None if we generated a new token in this request. 
+        * token: the raw token data; random (non-ascii) bytes. 
+        * timestamp: the time this token was generated (will not be accurate 
+          for version 1 cookies) 
+        """ 
+        if not hasattr(self, '_raw_xsrf_token'): 
+            cookie = self.get_cookie("_xsrf") 
+            if cookie: 
+                version, token, timestamp = self._decode_xsrf_token(cookie) 
+            else: 
+                version, token, timestamp = None, None, None 
+            if token is None: 
+                version = None 
+                token = os.urandom(16) 
+                timestamp = time.time() 
+            self._raw_xsrf_token = (version, token, timestamp) 
+        return self._raw_xsrf_token 
+ 
+    def _decode_xsrf_token(self, cookie): 
+        """Convert a cookie string into a the tuple form returned by 
+        _get_raw_xsrf_token. 
+        """ 
+ 
+        try: 
+            m = _signed_value_version_re.match(utf8(cookie)) 
+ 
+            if m: 
+                version = int(m.group(1)) 
+                if version == 2: 
+                    _, mask, masked_token, timestamp = cookie.split("|") 
+ 
+                    mask = binascii.a2b_hex(utf8(mask)) 
+                    token = _websocket_mask( 
+                        mask, binascii.a2b_hex(utf8(masked_token))) 
+                    timestamp = int(timestamp) 
+                    return version, token, timestamp 
+                else: 
+                    # Treat unknown versions as not present instead of failing. 
+                    raise Exception("Unknown xsrf cookie version") 
+            else: 
+                version = 1 
+                try: 
+                    token = binascii.a2b_hex(utf8(cookie)) 
+                except (binascii.Error, TypeError): 
+                    token = utf8(cookie) 
+                # We don't have a usable timestamp in older versions. 
+                timestamp = int(time.time()) 
+                return (version, token, timestamp) 
+        except Exception: 
+            # Catch exceptions and return nothing instead of failing. 
+            gen_log.debug("Uncaught exception in _decode_xsrf_token", 
+                          exc_info=True) 
+            return None, None, None 
+ 
+    def check_xsrf_cookie(self): 
+        """Verifies that the ``_xsrf`` cookie matches the ``_xsrf`` argument. 
+ 
+        To prevent cross-site request forgery, we set an ``_xsrf`` 
+        cookie and include the same value as a non-cookie 
+        field with all ``POST`` requests. If the two do not match, we 
+        reject the form submission as a potential forgery. 
+ 
+        The ``_xsrf`` value may be set as either a form field named ``_xsrf`` 
+        or in a custom HTTP header named ``X-XSRFToken`` or ``X-CSRFToken`` 
+        (the latter is accepted for compatibility with Django). 
+ 
+        See http://en.wikipedia.org/wiki/Cross-site_request_forgery 
+ 
+        Prior to release 1.1.1, this check was ignored if the HTTP header 
+        ``X-Requested-With: XMLHTTPRequest`` was present.  This exception 
+        has been shown to be insecure and has been removed.  For more 
+        information please see 
+        http://www.djangoproject.com/weblog/2011/feb/08/security/ 
+        http://weblog.rubyonrails.org/2011/2/8/csrf-protection-bypass-in-ruby-on-rails 
+ 
+        .. versionchanged:: 3.2.2 
+           Added support for cookie version 2.  Both versions 1 and 2 are 
+           supported. 
+        """ 
+        token = (self.get_argument("_xsrf", None) or 
+                 self.request.headers.get("X-Xsrftoken") or 
+                 self.request.headers.get("X-Csrftoken")) 
+        if not token: 
+            raise HTTPError(403, "'_xsrf' argument missing from POST") 
+        _, token, _ = self._decode_xsrf_token(token) 
+        _, expected_token, _ = self._get_raw_xsrf_token() 
+        if not token: 
+            raise HTTPError(403, "'_xsrf' argument has invalid format") 
+        if not _time_independent_equals(utf8(token), utf8(expected_token)): 
+            raise HTTPError(403, "XSRF cookie does not match POST argument") 
+ 
+    def xsrf_form_html(self): 
+        """An HTML ``<input/>`` element to be included with all POST forms. 
+ 
+        It defines the ``_xsrf`` input value, which we check on all POST 
+        requests to prevent cross-site request forgery. If you have set 
+        the ``xsrf_cookies`` application setting, you must include this 
+        HTML within all of your HTML forms. 
+ 
+        In a template, this method should be called with ``{% module 
+        xsrf_form_html() %}`` 
+ 
+        See `check_xsrf_cookie()` above for more information. 
+        """ 
+        return '<input type="hidden" name="_xsrf" value="' + \ 
+            escape.xhtml_escape(self.xsrf_token) + '"/>' 
+ 
+    def static_url(self, path, include_host=None, **kwargs): 
+        """Returns a static URL for the given relative static file path. 
+ 
+        This method requires you set the ``static_path`` setting in your 
+        application (which specifies the root directory of your static 
+        files). 
+ 
+        This method returns a versioned url (by default appending 
+        ``?v=<signature>``), which allows the static files to be 
+        cached indefinitely.  This can be disabled by passing 
+        ``include_version=False`` (in the default implementation; 
+        other static file implementations are not required to support 
+        this, but they may support other options). 
+ 
+        By default this method returns URLs relative to the current 
+        host, but if ``include_host`` is true the URL returned will be 
+        absolute.  If this handler has an ``include_host`` attribute, 
+        that value will be used as the default for all `static_url` 
+        calls that do not pass ``include_host`` as a keyword argument. 
+ 
+        """ 
+        self.require_setting("static_path", "static_url") 
+        get_url = self.settings.get("static_handler_class", 
+                                    StaticFileHandler).make_static_url 
+ 
+        if include_host is None: 
+            include_host = getattr(self, "include_host", False) 
+ 
+        if include_host: 
+            base = self.request.protocol + "://" + self.request.host 
+        else: 
+            base = "" 
+ 
+        return base + get_url(self.settings, path, **kwargs) 
+ 
+    def require_setting(self, name, feature="this feature"): 
+        """Raises an exception if the given app setting is not defined.""" 
+        if not self.application.settings.get(name): 
+            raise Exception("You must define the '%s' setting in your " 
+                            "application to use %s" % (name, feature)) 
+ 
+    def reverse_url(self, name, *args): 
+        """Alias for `Application.reverse_url`.""" 
+        return self.application.reverse_url(name, *args) 
+ 
+    def compute_etag(self): 
+        """Computes the etag header to be used for this request. 
+ 
+        By default uses a hash of the content written so far. 
+ 
+        May be overridden to provide custom etag implementations, 
+        or may return None to disable tornado's default etag support. 
+        """ 
+        hasher = hashlib.sha1() 
+        for part in self._write_buffer: 
+            hasher.update(part) 
+        return '"%s"' % hasher.hexdigest() 
+ 
+    def set_etag_header(self): 
+        """Sets the response's Etag header using ``self.compute_etag()``. 
+ 
+        Note: no header will be set if ``compute_etag()`` returns ``None``. 
+ 
+        This method is called automatically when the request is finished. 
+        """ 
+        etag = self.compute_etag() 
+        if etag is not None: 
+            self.set_header("Etag", etag) 
+ 
+    def check_etag_header(self): 
+        """Checks the ``Etag`` header against requests's ``If-None-Match``. 
+ 
+        Returns ``True`` if the request's Etag matches and a 304 should be 
+        returned. For example:: 
+ 
+            self.set_etag_header() 
+            if self.check_etag_header(): 
+                self.set_status(304) 
+                return 
+ 
+        This method is called automatically when the request is finished, 
+        but may be called earlier for applications that override 
+        `compute_etag` and want to do an early check for ``If-None-Match`` 
+        before completing the request.  The ``Etag`` header should be set 
+        (perhaps with `set_etag_header`) before calling this method. 
+        """ 
+        computed_etag = utf8(self._headers.get("Etag", "")) 
+        # Find all weak and strong etag values from If-None-Match header 
+        # because RFC 7232 allows multiple etag values in a single header. 
+        etags = re.findall( 
+            br'\*|(?:W/)?"[^"]*"', 
+            utf8(self.request.headers.get("If-None-Match", "")) 
+        ) 
+        if not computed_etag or not etags: 
+            return False 
+ 
+        match = False 
+        if etags[0] == b'*': 
+            match = True 
+        else: 
+            # Use a weak comparison when comparing entity-tags. 
+            def val(x): 
+                return x[2:] if x.startswith(b'W/') else x 
+ 
+            for etag in etags: 
+                if val(etag) == val(computed_etag): 
+                    match = True 
+                    break 
+        return match 
+ 
+    def _stack_context_handle_exception(self, type, value, traceback): 
+        try: 
+            # For historical reasons _handle_request_exception only takes 
+            # the exception value instead of the full triple, 
+            # so re-raise the exception to ensure that it's in 
+            # sys.exc_info() 
+            raise_exc_info((type, value, traceback)) 
+        except Exception: 
+            self._handle_request_exception(value) 
+        return True 
+ 
+    @gen.coroutine 
+    def _execute(self, transforms, *args, **kwargs): 
+        """Executes this request with the given output transforms.""" 
+        self._transforms = transforms 
+        try: 
+            if self.request.method not in self.SUPPORTED_METHODS: 
+                raise HTTPError(405) 
+            self.path_args = [self.decode_argument(arg) for arg in args] 
+            self.path_kwargs = dict((k, self.decode_argument(v, name=k)) 
+                                    for (k, v) in kwargs.items()) 
+            # If XSRF cookies are turned on, reject form submissions without 
+            # the proper cookie 
+            if self.request.method not in ("GET", "HEAD", "OPTIONS") and \ 
+                    self.application.settings.get("xsrf_cookies"): 
+                self.check_xsrf_cookie() 
+ 
+            result = self.prepare() 
+            if result is not None: 
+                result = yield result 
+            if self._prepared_future is not None: 
+                # Tell the Application we've finished with prepare() 
+                # and are ready for the body to arrive. 
+                self._prepared_future.set_result(None) 
+            if self._finished: 
+                return 
+ 
+            if _has_stream_request_body(self.__class__): 
+                # In streaming mode request.body is a Future that signals 
+                # the body has been completely received.  The Future has no 
+                # result; the data has been passed to self.data_received 
+                # instead. 
+                try: 
+                    yield self.request.body 
+                except iostream.StreamClosedError: 
+                    return 
+ 
+            method = getattr(self, self.request.method.lower()) 
+            result = method(*self.path_args, **self.path_kwargs) 
+            if result is not None: 
+                result = yield result 
+            if self._auto_finish and not self._finished: 
+                self.finish() 
+        except Exception as e: 
+            try: 
+                self._handle_request_exception(e) 
+            except Exception: 
+                app_log.error("Exception in exception handler", exc_info=True) 
+            if (self._prepared_future is not None and 
+                    not self._prepared_future.done()): 
+                # In case we failed before setting _prepared_future, do it 
+                # now (to unblock the HTTP server).  Note that this is not 
+                # in a finally block to avoid GC issues prior to Python 3.4. 
+                self._prepared_future.set_result(None) 
+ 
+    def data_received(self, chunk): 
+        """Implement this method to handle streamed request data. 
+ 
+        Requires the `.stream_request_body` decorator. 
+        """ 
+        raise NotImplementedError() 
+ 
+    def _log(self): 
+        """Logs the current request. 
+ 
+        Sort of deprecated since this functionality was moved to the 
+        Application, but left in place for the benefit of existing apps 
+        that have overridden this method. 
+        """ 
+        self.application.log_request(self) 
+ 
+    def _request_summary(self): 
+        return "%s %s (%s)" % (self.request.method, self.request.uri, 
+                               self.request.remote_ip) 
+ 
+    def _handle_request_exception(self, e): 
+        if isinstance(e, Finish): 
+            # Not an error; just finish the request without logging. 
+            if not self._finished: 
+                self.finish(*e.args) 
+            return 
+        try: 
+            self.log_exception(*sys.exc_info()) 
+        except Exception: 
+            # An error here should still get a best-effort send_error() 
+            # to avoid leaking the connection. 
+            app_log.error("Error in exception logger", exc_info=True) 
+        if self._finished: 
+            # Extra errors after the request has been finished should 
+            # be logged, but there is no reason to continue to try and 
+            # send a response. 
+            return 
+        if isinstance(e, HTTPError): 
+            if e.status_code not in httputil.responses and not e.reason: 
+                gen_log.error("Bad HTTP status code: %d", e.status_code) 
+                self.send_error(500, exc_info=sys.exc_info()) 
+            else: 
+                self.send_error(e.status_code, exc_info=sys.exc_info()) 
+        else: 
+            self.send_error(500, exc_info=sys.exc_info()) 
+ 
+    def log_exception(self, typ, value, tb): 
+        """Override to customize logging of uncaught exceptions. 
+ 
+        By default logs instances of `HTTPError` as warnings without 
+        stack traces (on the ``tornado.general`` logger), and all 
+        other exceptions as errors with stack traces (on the 
+        ``tornado.application`` logger). 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        if isinstance(value, HTTPError): 
+            if value.log_message: 
+                format = "%d %s: " + value.log_message 
+                args = ([value.status_code, self._request_summary()] + 
+                        list(value.args)) 
+                gen_log.warning(format, *args) 
+        else: 
+            app_log.error("Uncaught exception %s\n%r", self._request_summary(), 
+                          self.request, exc_info=(typ, value, tb)) 
+ 
+    def _ui_module(self, name, module): 
+        def render(*args, **kwargs): 
+            if not hasattr(self, "_active_modules"): 
+                self._active_modules = {} 
+            if name not in self._active_modules: 
+                self._active_modules[name] = module(self) 
+            rendered = self._active_modules[name].render(*args, **kwargs) 
+            return rendered 
+        return render 
+ 
+    def _ui_method(self, method): 
+        return lambda *args, **kwargs: method(self, *args, **kwargs) 
+ 
+    def _clear_headers_for_304(self): 
+        # 304 responses should not contain entity headers (defined in 
+        # http://www.w3.org/Protocols/rfc2616/rfc2616-sec7.html#sec7.1) 
+        # not explicitly allowed by 
+        # http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.5 
+        headers = ["Allow", "Content-Encoding", "Content-Language", 
+                   "Content-Length", "Content-MD5", "Content-Range", 
+                   "Content-Type", "Last-Modified"] 
+        for h in headers: 
+            self.clear_header(h) 
+ 
+ 
+def asynchronous(method): 
+    """Wrap request handler methods with this if they are asynchronous. 
+ 
+    This decorator is for callback-style asynchronous methods; for 
+    coroutines, use the ``@gen.coroutine`` decorator without 
+    ``@asynchronous``. (It is legal for legacy reasons to use the two 
+    decorators together provided ``@asynchronous`` is first, but 
+    ``@asynchronous`` will be ignored in this case) 
+ 
+    This decorator should only be applied to the :ref:`HTTP verb 
+    methods <verbs>`; its behavior is undefined for any other method. 
+    This decorator does not *make* a method asynchronous; it tells 
+    the framework that the method *is* asynchronous.  For this decorator 
+    to be useful the method must (at least sometimes) do something 
+    asynchronous. 
+ 
+    If this decorator is given, the response is not finished when the 
+    method returns. It is up to the request handler to call 
+    `self.finish() <RequestHandler.finish>` to finish the HTTP 
+    request. Without this decorator, the request is automatically 
+    finished when the ``get()`` or ``post()`` method returns. Example: 
+ 
+    .. testcode:: 
+ 
+       class MyRequestHandler(RequestHandler): 
+           @asynchronous 
+           def get(self): 
+              http = httpclient.AsyncHTTPClient() 
+              http.fetch("http://friendfeed.com/", self._on_download) 
+ 
+           def _on_download(self, response): 
+              self.write("Downloaded!") 
+              self.finish() 
+ 
+    .. testoutput:: 
+       :hide: 
+ 
+    .. versionchanged:: 3.1 
+       The ability to use ``@gen.coroutine`` without ``@asynchronous``. 
+ 
+    .. versionchanged:: 4.3 Returning anything but ``None`` or a 
+       yieldable object from a method decorated with ``@asynchronous`` 
+       is an error. Such return values were previously ignored silently. 
+    """ 
+    # Delay the IOLoop import because it's not available on app engine. 
+    from tornado.ioloop import IOLoop 
+ 
+    @functools.wraps(method) 
+    def wrapper(self, *args, **kwargs): 
+        self._auto_finish = False 
+        with stack_context.ExceptionStackContext( 
+                self._stack_context_handle_exception): 
+            result = method(self, *args, **kwargs) 
+            if result is not None: 
+                result = gen.convert_yielded(result) 
+ 
+                # If @asynchronous is used with @gen.coroutine, (but 
+                # not @gen.engine), we can automatically finish the 
+                # request when the future resolves.  Additionally, 
+                # the Future will swallow any exceptions so we need 
+                # to throw them back out to the stack context to finish 
+                # the request. 
+                def future_complete(f): 
+                    f.result() 
+                    if not self._finished: 
+                        self.finish() 
+                IOLoop.current().add_future(result, future_complete) 
+                # Once we have done this, hide the Future from our 
+                # caller (i.e. RequestHandler._when_complete), which 
+                # would otherwise set up its own callback and 
+                # exception handler (resulting in exceptions being 
+                # logged twice). 
+                return None 
+            return result 
+    return wrapper 
+ 
+ 
+def stream_request_body(cls): 
+    """Apply to `RequestHandler` subclasses to enable streaming body support. 
+ 
+    This decorator implies the following changes: 
+ 
+    * `.HTTPServerRequest.body` is undefined, and body arguments will not 
+      be included in `RequestHandler.get_argument`. 
+    * `RequestHandler.prepare` is called when the request headers have been 
+      read instead of after the entire body has been read. 
+    * The subclass must define a method ``data_received(self, data):``, which 
+      will be called zero or more times as data is available.  Note that 
+      if the request has an empty body, ``data_received`` may not be called. 
+    * ``prepare`` and ``data_received`` may return Futures (such as via 
+      ``@gen.coroutine``, in which case the next method will not be called 
+      until those futures have completed. 
+    * The regular HTTP method (``post``, ``put``, etc) will be called after 
+      the entire body has been read. 
+ 
+    See the `file receiver demo <https://github.com/tornadoweb/tornado/tree/master/demos/file_upload/>`_ 
+    for example usage. 
+    """ 
+    if not issubclass(cls, RequestHandler): 
+        raise TypeError("expected subclass of RequestHandler, got %r", cls) 
+    cls._stream_request_body = True 
+    return cls 
+ 
+ 
+def _has_stream_request_body(cls): 
+    if not issubclass(cls, RequestHandler): 
+        raise TypeError("expected subclass of RequestHandler, got %r", cls) 
+    return getattr(cls, '_stream_request_body', False) 
+ 
+ 
+def removeslash(method): 
+    """Use this decorator to remove trailing slashes from the request path. 
+ 
+    For example, a request to ``/foo/`` would redirect to ``/foo`` with this 
+    decorator. Your request handler mapping should use a regular expression 
+    like ``r'/foo/*'`` in conjunction with using the decorator. 
+    """ 
+    @functools.wraps(method) 
+    def wrapper(self, *args, **kwargs): 
+        if self.request.path.endswith("/"): 
+            if self.request.method in ("GET", "HEAD"): 
+                uri = self.request.path.rstrip("/") 
+                if uri:  # don't try to redirect '/' to '' 
+                    if self.request.query: 
+                        uri += "?" + self.request.query 
+                    self.redirect(uri, permanent=True) 
+                    return 
+            else: 
+                raise HTTPError(404) 
+        return method(self, *args, **kwargs) 
+    return wrapper 
+ 
+ 
+def addslash(method): 
+    """Use this decorator to add a missing trailing slash to the request path. 
+ 
+    For example, a request to ``/foo`` would redirect to ``/foo/`` with this 
+    decorator. Your request handler mapping should use a regular expression 
+    like ``r'/foo/?'`` in conjunction with using the decorator. 
+    """ 
+    @functools.wraps(method) 
+    def wrapper(self, *args, **kwargs): 
+        if not self.request.path.endswith("/"): 
+            if self.request.method in ("GET", "HEAD"): 
+                uri = self.request.path + "/" 
+                if self.request.query: 
+                    uri += "?" + self.request.query 
+                self.redirect(uri, permanent=True) 
+                return 
+            raise HTTPError(404) 
+        return method(self, *args, **kwargs) 
+    return wrapper 
+ 
+ 
+class _ApplicationRouter(ReversibleRuleRouter): 
+    """Routing implementation used internally by `Application`. 
+ 
+    Provides a binding between `Application` and `RequestHandler`. 
+    This implementation extends `~.routing.ReversibleRuleRouter` in a couple of ways: 
+        * it allows to use `RequestHandler` subclasses as `~.routing.Rule` target and 
+        * it allows to use a list/tuple of rules as `~.routing.Rule` target. 
+        ``process_rule`` implementation will substitute this list with an appropriate 
+        `_ApplicationRouter` instance. 
+    """ 
+ 
+    def __init__(self, application, rules=None): 
+        assert isinstance(application, Application) 
+        self.application = application 
+        super(_ApplicationRouter, self).__init__(rules) 
+ 
+    def process_rule(self, rule): 
+        rule = super(_ApplicationRouter, self).process_rule(rule) 
+ 
+        if isinstance(rule.target, (list, tuple)): 
+            rule.target = _ApplicationRouter(self.application, rule.target) 
+ 
+        return rule 
+ 
+    def get_target_delegate(self, target, request, **target_params): 
+        if isclass(target) and issubclass(target, RequestHandler): 
+            return self.application.get_handler_delegate(request, target, **target_params) 
+ 
+        return super(_ApplicationRouter, self).get_target_delegate(target, request, **target_params) 
+ 
+ 
+class Application(ReversibleRouter): 
+    """A collection of request handlers that make up a web application. 
+ 
+    Instances of this class are callable and can be passed directly to 
+    HTTPServer to serve the application:: 
+ 
+        application = web.Application([ 
+            (r"/", MainPageHandler), 
+        ]) 
+        http_server = httpserver.HTTPServer(application) 
+        http_server.listen(8080) 
+        ioloop.IOLoop.current().start() 
+ 
+    The constructor for this class takes in a list of `~.routing.Rule` 
+    objects or tuples of values corresponding to the arguments of 
+    `~.routing.Rule` constructor: ``(matcher, target, [target_kwargs], [name])``, 
+    the values in square brackets being optional. The default matcher is 
+    `~.routing.PathMatches`, so ``(regexp, target)`` tuples can also be used 
+    instead of ``(PathMatches(regexp), target)``. 
+ 
+    A common routing target is a `RequestHandler` subclass, but you can also 
+    use lists of rules as a target, which create a nested routing configuration:: 
+ 
+        application = web.Application([ 
+            (HostMatches("example.com"), [ 
+                (r"/", MainPageHandler), 
+                (r"/feed", FeedHandler), 
+            ]), 
+        ]) 
+ 
+    In addition to this you can use nested `~.routing.Router` instances, 
+    `~.httputil.HTTPMessageDelegate` subclasses and callables as routing targets 
+    (see `~.routing` module docs for more information). 
+ 
+    When we receive requests, we iterate over the list in order and 
+    instantiate an instance of the first request class whose regexp 
+    matches the request path. The request class can be specified as 
+    either a class object or a (fully-qualified) name. 
+ 
+    A dictionary may be passed as the third element (``target_kwargs``) 
+    of the tuple, which will be used as keyword arguments to the handler's 
+    constructor and `~RequestHandler.initialize` method. This pattern 
+    is used for the `StaticFileHandler` in this example (note that a 
+    `StaticFileHandler` can be installed automatically with the 
+    static_path setting described below):: 
+ 
+        application = web.Application([ 
+            (r"/static/(.*)", web.StaticFileHandler, {"path": "/var/www"}), 
+        ]) 
+ 
+    We support virtual hosts with the `add_handlers` method, which takes in 
+    a host regular expression as the first argument:: 
+ 
+        application.add_handlers(r"www\.myhost\.com", [ 
+            (r"/article/([0-9]+)", ArticleHandler), 
+        ]) 
+ 
+    If there's no match for the current request's host, then ``default_host`` 
+    parameter value is matched against host regular expressions. 
+ 
+    You can serve static files by sending the ``static_path`` setting 
+    as a keyword argument. We will serve those files from the 
+    ``/static/`` URI (this is configurable with the 
+    ``static_url_prefix`` setting), and we will serve ``/favicon.ico`` 
+    and ``/robots.txt`` from the same directory.  A custom subclass of 
+    `StaticFileHandler` can be specified with the 
+    ``static_handler_class`` setting. 
+ 
+    .. versionchanged:: 4.5 
+       Integration with the new `tornado.routing` module. 
+    """ 
+    def __init__(self, handlers=None, default_host=None, transforms=None, 
+                 **settings): 
+        if transforms is None: 
+            self.transforms = [] 
+            if settings.get("compress_response") or settings.get("gzip"): 
+                self.transforms.append(GZipContentEncoding) 
+        else: 
+            self.transforms = transforms 
+        self.default_host = default_host 
+        self.settings = settings 
+        self.ui_modules = {'linkify': _linkify, 
+                           'xsrf_form_html': _xsrf_form_html, 
+                           'Template': TemplateModule, 
+                           } 
+        self.ui_methods = {} 
+        self._load_ui_modules(settings.get("ui_modules", {})) 
+        self._load_ui_methods(settings.get("ui_methods", {})) 
+        if self.settings.get("static_path"): 
+            path = self.settings["static_path"] 
+            handlers = list(handlers or []) 
+            static_url_prefix = settings.get("static_url_prefix", 
+                                             "/static/") 
+            static_handler_class = settings.get("static_handler_class", 
+                                                StaticFileHandler) 
+            static_handler_args = settings.get("static_handler_args", {}) 
+            static_handler_args['path'] = path 
+            for pattern in [re.escape(static_url_prefix) + r"(.*)", 
+                            r"/(favicon\.ico)", r"/(robots\.txt)"]: 
+                handlers.insert(0, (pattern, static_handler_class, 
+                                    static_handler_args)) 
+ 
+        if self.settings.get('debug'): 
+            self.settings.setdefault('autoreload', True) 
+            self.settings.setdefault('compiled_template_cache', False) 
+            self.settings.setdefault('static_hash_cache', False) 
+            self.settings.setdefault('serve_traceback', True) 
+ 
+        self.wildcard_router = _ApplicationRouter(self, handlers) 
+        self.default_router = _ApplicationRouter(self, [ 
+            Rule(AnyMatches(), self.wildcard_router) 
+        ]) 
+ 
+        # Automatically reload modified modules 
+        if self.settings.get('autoreload'): 
+            from tornado import autoreload 
+            autoreload.start() 
+ 
+    def listen(self, port, address="", **kwargs): 
+        """Starts an HTTP server for this application on the given port. 
+ 
+        This is a convenience alias for creating an `.HTTPServer` 
+        object and calling its listen method.  Keyword arguments not 
+        supported by `HTTPServer.listen <.TCPServer.listen>` are passed to the 
+        `.HTTPServer` constructor.  For advanced uses 
+        (e.g. multi-process mode), do not use this method; create an 
+        `.HTTPServer` and call its 
+        `.TCPServer.bind`/`.TCPServer.start` methods directly. 
+ 
+        Note that after calling this method you still need to call 
+        ``IOLoop.current().start()`` to start the server. 
+ 
+        Returns the `.HTTPServer` object. 
+ 
+        .. versionchanged:: 4.3 
+           Now returns the `.HTTPServer` object. 
+        """ 
+        # import is here rather than top level because HTTPServer 
+        # is not importable on appengine 
+        from tornado.httpserver import HTTPServer 
+        server = HTTPServer(self, **kwargs) 
+        server.listen(port, address) 
+        return server 
+ 
+    def add_handlers(self, host_pattern, host_handlers): 
+        """Appends the given handlers to our handler list. 
+ 
+        Host patterns are processed sequentially in the order they were 
+        added. All matching patterns will be considered. 
+        """ 
+        host_matcher = HostMatches(host_pattern) 
+        rule = Rule(host_matcher, _ApplicationRouter(self, host_handlers)) 
+ 
+        self.default_router.rules.insert(-1, rule) 
+ 
+        if self.default_host is not None: 
+            self.wildcard_router.add_rules([( 
+                DefaultHostMatches(self, host_matcher.host_pattern), 
+                host_handlers 
+            )]) 
+ 
+    def add_transform(self, transform_class): 
+        self.transforms.append(transform_class) 
+ 
+    def _load_ui_methods(self, methods): 
+        if isinstance(methods, types.ModuleType): 
+            self._load_ui_methods(dict((n, getattr(methods, n)) 
+                                       for n in dir(methods))) 
+        elif isinstance(methods, list): 
+            for m in methods: 
+                self._load_ui_methods(m) 
+        else: 
+            for name, fn in methods.items(): 
+                if not name.startswith("_") and hasattr(fn, "__call__") \ 
+                        and name[0].lower() == name[0]: 
+                    self.ui_methods[name] = fn 
+ 
+    def _load_ui_modules(self, modules): 
+        if isinstance(modules, types.ModuleType): 
+            self._load_ui_modules(dict((n, getattr(modules, n)) 
+                                       for n in dir(modules))) 
+        elif isinstance(modules, list): 
+            for m in modules: 
+                self._load_ui_modules(m) 
+        else: 
+            assert isinstance(modules, dict) 
+            for name, cls in modules.items(): 
+                try: 
+                    if issubclass(cls, UIModule): 
+                        self.ui_modules[name] = cls 
+                except TypeError: 
+                    pass 
+ 
+    def __call__(self, request): 
+        # Legacy HTTPServer interface 
+        dispatcher = self.find_handler(request) 
+        return dispatcher.execute() 
+ 
+    def find_handler(self, request, **kwargs): 
+        route = self.default_router.find_handler(request) 
+        if route is not None: 
+            return route 
+ 
+        if self.settings.get('default_handler_class'): 
+            return self.get_handler_delegate( 
+                request, 
+                self.settings['default_handler_class'], 
+                self.settings.get('default_handler_args', {})) 
+ 
+        return self.get_handler_delegate( 
+            request, ErrorHandler, {'status_code': 404}) 
+ 
+    def get_handler_delegate(self, request, target_class, target_kwargs=None, 
+                             path_args=None, path_kwargs=None): 
+        """Returns `~.httputil.HTTPMessageDelegate` that can serve a request 
+        for application and `RequestHandler` subclass. 
+ 
+        :arg httputil.HTTPServerRequest request: current HTTP request. 
+        :arg RequestHandler target_class: a `RequestHandler` class. 
+        :arg dict target_kwargs: keyword arguments for ``target_class`` constructor. 
+        :arg list path_args: positional arguments for ``target_class`` HTTP method that 
+            will be executed while handling a request (``get``, ``post`` or any other). 
+        :arg dict path_kwargs: keyword arguments for ``target_class`` HTTP method. 
+        """ 
+        return _HandlerDelegate( 
+            self, request, target_class, target_kwargs, path_args, path_kwargs) 
+ 
+    def reverse_url(self, name, *args): 
+        """Returns a URL path for handler named ``name`` 
+ 
+        The handler must be added to the application as a named `URLSpec`. 
+ 
+        Args will be substituted for capturing groups in the `URLSpec` regex. 
+        They will be converted to strings if necessary, encoded as utf8, 
+        and url-escaped. 
+        """ 
+        reversed_url = self.default_router.reverse_url(name, *args) 
+        if reversed_url is not None: 
+            return reversed_url 
+ 
+        raise KeyError("%s not found in named urls" % name) 
+ 
+    def log_request(self, handler): 
+        """Writes a completed HTTP request to the logs. 
+ 
+        By default writes to the python root logger.  To change 
+        this behavior either subclass Application and override this method, 
+        or pass a function in the application settings dictionary as 
+        ``log_function``. 
+        """ 
+        if "log_function" in self.settings: 
+            self.settings["log_function"](handler) 
+            return 
+        if handler.get_status() < 400: 
+            log_method = access_log.info 
+        elif handler.get_status() < 500: 
+            log_method = access_log.warning 
+        else: 
+            log_method = access_log.error 
+        request_time = 1000.0 * handler.request.request_time() 
+        log_method("%d %s %.2fms", handler.get_status(), 
+                   handler._request_summary(), request_time) 
+ 
+ 
+class _HandlerDelegate(httputil.HTTPMessageDelegate): 
+    def __init__(self, application, request, handler_class, handler_kwargs, 
+                 path_args, path_kwargs): 
+        self.application = application 
+        self.connection = request.connection 
+        self.request = request 
+        self.handler_class = handler_class 
+        self.handler_kwargs = handler_kwargs or {} 
+        self.path_args = path_args or [] 
+        self.path_kwargs = path_kwargs or {} 
+        self.chunks = [] 
+        self.stream_request_body = _has_stream_request_body(self.handler_class) 
+ 
+    def headers_received(self, start_line, headers): 
+        if self.stream_request_body: 
+            self.request.body = Future() 
+            return self.execute() 
+ 
+    def data_received(self, data): 
+        if self.stream_request_body: 
+            return self.handler.data_received(data) 
+        else: 
+            self.chunks.append(data) 
+ 
+    def finish(self): 
+        if self.stream_request_body: 
+            self.request.body.set_result(None) 
+        else: 
+            self.request.body = b''.join(self.chunks) 
+            self.request._parse_body() 
+            self.execute() 
+ 
+    def on_connection_close(self): 
+        if self.stream_request_body: 
+            self.handler.on_connection_close() 
+        else: 
+            self.chunks = None 
+ 
+    def execute(self): 
+        # If template cache is disabled (usually in the debug mode), 
+        # re-compile templates and reload static files on every 
+        # request so you don't need to restart to see changes 
+        if not self.application.settings.get("compiled_template_cache", True): 
+            with RequestHandler._template_loader_lock: 
+                for loader in RequestHandler._template_loaders.values(): 
+                    loader.reset() 
+        if not self.application.settings.get('static_hash_cache', True): 
+            StaticFileHandler.reset() 
+ 
+        self.handler = self.handler_class(self.application, self.request, 
+                                          **self.handler_kwargs) 
+        transforms = [t(self.request) for t in self.application.transforms] 
+ 
+        if self.stream_request_body: 
+            self.handler._prepared_future = Future() 
+        # Note that if an exception escapes handler._execute it will be 
+        # trapped in the Future it returns (which we are ignoring here, 
+        # leaving it to be logged when the Future is GC'd). 
+        # However, that shouldn't happen because _execute has a blanket 
+        # except handler, and we cannot easily access the IOLoop here to 
+        # call add_future (because of the requirement to remain compatible 
+        # with WSGI) 
+        self.handler._execute(transforms, *self.path_args, 
+                              **self.path_kwargs) 
+        # If we are streaming the request body, then execute() is finished 
+        # when the handler has prepared to receive the body.  If not, 
+        # it doesn't matter when execute() finishes (so we return None) 
+        return self.handler._prepared_future 
+ 
+ 
+class HTTPError(Exception): 
+    """An exception that will turn into an HTTP error response. 
+ 
+    Raising an `HTTPError` is a convenient alternative to calling 
+    `RequestHandler.send_error` since it automatically ends the 
+    current function. 
+ 
+    To customize the response sent with an `HTTPError`, override 
+    `RequestHandler.write_error`. 
+ 
+    :arg int status_code: HTTP status code.  Must be listed in 
+        `httplib.responses <http.client.responses>` unless the ``reason`` 
+        keyword argument is given. 
+    :arg string log_message: Message to be written to the log for this error 
+        (will not be shown to the user unless the `Application` is in debug 
+        mode).  May contain ``%s``-style placeholders, which will be filled 
+        in with remaining positional parameters. 
+    :arg string reason: Keyword-only argument.  The HTTP "reason" phrase 
+        to pass in the status line along with ``status_code``.  Normally 
+        determined automatically from ``status_code``, but can be used 
+        to use a non-standard numeric code. 
+    """ 
+    def __init__(self, status_code=500, log_message=None, *args, **kwargs): 
+        self.status_code = status_code 
+        self.log_message = log_message 
+        self.args = args 
+        self.reason = kwargs.get('reason', None) 
+        if log_message and not args: 
+            self.log_message = log_message.replace('%', '%%') 
+ 
+    def __str__(self): 
+        message = "HTTP %d: %s" % ( 
+            self.status_code, 
+            self.reason or httputil.responses.get(self.status_code, 'Unknown')) 
+        if self.log_message: 
+            return message + " (" + (self.log_message % self.args) + ")" 
+        else: 
+            return message 
+ 
+ 
+class Finish(Exception): 
+    """An exception that ends the request without producing an error response. 
+ 
+    When `Finish` is raised in a `RequestHandler`, the request will 
+    end (calling `RequestHandler.finish` if it hasn't already been 
+    called), but the error-handling methods (including 
+    `RequestHandler.write_error`) will not be called. 
+ 
+    If `Finish()` was created with no arguments, the pending response 
+    will be sent as-is. If `Finish()` was given an argument, that 
+    argument will be passed to `RequestHandler.finish()`. 
+ 
+    This can be a more convenient way to implement custom error pages 
+    than overriding ``write_error`` (especially in library code):: 
+ 
+        if self.current_user is None: 
+            self.set_status(401) 
+            self.set_header('WWW-Authenticate', 'Basic realm="something"') 
+            raise Finish() 
+ 
+    .. versionchanged:: 4.3 
+       Arguments passed to ``Finish()`` will be passed on to 
+       `RequestHandler.finish`. 
+    """ 
+    pass 
+ 
+ 
+class MissingArgumentError(HTTPError): 
+    """Exception raised by `RequestHandler.get_argument`. 
+ 
+    This is a subclass of `HTTPError`, so if it is uncaught a 400 response 
+    code will be used instead of 500 (and a stack trace will not be logged). 
+ 
+    .. versionadded:: 3.1 
+    """ 
+    def __init__(self, arg_name): 
+        super(MissingArgumentError, self).__init__( 
+            400, 'Missing argument %s' % arg_name) 
+        self.arg_name = arg_name 
+ 
+ 
+class ErrorHandler(RequestHandler): 
+    """Generates an error response with ``status_code`` for all requests.""" 
+    def initialize(self, status_code): 
+        self.set_status(status_code) 
+ 
+    def prepare(self): 
+        raise HTTPError(self._status_code) 
+ 
+    def check_xsrf_cookie(self): 
+        # POSTs to an ErrorHandler don't actually have side effects, 
+        # so we don't need to check the xsrf token.  This allows POSTs 
+        # to the wrong url to return a 404 instead of 403. 
+        pass 
+ 
+ 
+class RedirectHandler(RequestHandler): 
+    """Redirects the client to the given URL for all GET requests. 
+ 
+    You should provide the keyword argument ``url`` to the handler, e.g.:: 
+ 
+        application = web.Application([ 
+            (r"/oldpath", web.RedirectHandler, {"url": "/newpath"}), 
+        ]) 
+ 
+    `RedirectHandler` supports regular expression substitutions. E.g., to 
+    swap the first and second parts of a path while preserving the remainder:: 
+ 
+        application = web.Application([ 
+            (r"/(.*?)/(.*?)/(.*)", web.RedirectHandler, {"url": "/{1}/{0}/{2}"}), 
+        ]) 
+ 
+    The final URL is formatted with `str.format` and the substrings that match 
+    the capturing groups. In the above example, a request to "/a/b/c" would be 
+    formatted like:: 
+ 
+        str.format("/{1}/{0}/{2}", "a", "b", "c")  # -> "/b/a/c" 
+ 
+    Use Python's :ref:`format string syntax <formatstrings>` to customize how 
+    values are substituted. 
+ 
+    .. versionchanged:: 4.5 
+       Added support for substitutions into the destination URL. 
+    """ 
+    def initialize(self, url, permanent=True): 
+        self._url = url 
+        self._permanent = permanent 
+ 
+    def get(self, *args): 
+        self.redirect(self._url.format(*args), permanent=self._permanent) 
+ 
+ 
+class StaticFileHandler(RequestHandler): 
+    """A simple handler that can serve static content from a directory. 
+ 
+    A `StaticFileHandler` is configured automatically if you pass the 
+    ``static_path`` keyword argument to `Application`.  This handler 
+    can be customized with the ``static_url_prefix``, ``static_handler_class``, 
+    and ``static_handler_args`` settings. 
+ 
+    To map an additional path to this handler for a static data directory 
+    you would add a line to your application like:: 
+ 
+        application = web.Application([ 
+            (r"/content/(.*)", web.StaticFileHandler, {"path": "/var/www"}), 
+        ]) 
+ 
+    The handler constructor requires a ``path`` argument, which specifies the 
+    local root directory of the content to be served. 
+ 
+    Note that a capture group in the regex is required to parse the value for 
+    the ``path`` argument to the get() method (different than the constructor 
+    argument above); see `URLSpec` for details. 
+ 
+    To serve a file like ``index.html`` automatically when a directory is 
+    requested, set ``static_handler_args=dict(default_filename="index.html")`` 
+    in your application settings, or add ``default_filename`` as an initializer 
+    argument for your ``StaticFileHandler``. 
+ 
+    To maximize the effectiveness of browser caching, this class supports 
+    versioned urls (by default using the argument ``?v=``).  If a version 
+    is given, we instruct the browser to cache this file indefinitely. 
+    `make_static_url` (also available as `RequestHandler.static_url`) can 
+    be used to construct a versioned url. 
+ 
+    This handler is intended primarily for use in development and light-duty 
+    file serving; for heavy traffic it will be more efficient to use 
+    a dedicated static file server (such as nginx or Apache).  We support 
+    the HTTP ``Accept-Ranges`` mechanism to return partial content (because 
+    some browsers require this functionality to be present to seek in 
+    HTML5 audio or video). 
+ 
+    **Subclassing notes** 
+ 
+    This class is designed to be extensible by subclassing, but because 
+    of the way static urls are generated with class methods rather than 
+    instance methods, the inheritance patterns are somewhat unusual. 
+    Be sure to use the ``@classmethod`` decorator when overriding a 
+    class method.  Instance methods may use the attributes ``self.path`` 
+    ``self.absolute_path``, and ``self.modified``. 
+ 
+    Subclasses should only override methods discussed in this section; 
+    overriding other methods is error-prone.  Overriding 
+    ``StaticFileHandler.get`` is particularly problematic due to the 
+    tight coupling with ``compute_etag`` and other methods. 
+ 
+    To change the way static urls are generated (e.g. to match the behavior 
+    of another server or CDN), override `make_static_url`, `parse_url_path`, 
+    `get_cache_time`, and/or `get_version`. 
+ 
+    To replace all interaction with the filesystem (e.g. to serve 
+    static content from a database), override `get_content`, 
+    `get_content_size`, `get_modified_time`, `get_absolute_path`, and 
+    `validate_absolute_path`. 
+ 
+    .. versionchanged:: 3.1 
+       Many of the methods for subclasses were added in Tornado 3.1. 
+    """ 
+    CACHE_MAX_AGE = 86400 * 365 * 10  # 10 years 
+ 
+    _static_hashes = {}  # type: typing.Dict 
+    _lock = threading.Lock()  # protects _static_hashes 
+ 
+    def initialize(self, path, default_filename=None): 
+        self.root = path 
+        self.default_filename = default_filename 
+ 
+    @classmethod 
+    def reset(cls): 
+        with cls._lock: 
+            cls._static_hashes = {} 
+ 
+    def head(self, path): 
+        return self.get(path, include_body=False) 
+ 
+    @gen.coroutine 
+    def get(self, path, include_body=True): 
+        # Set up our path instance variables. 
+        self.path = self.parse_url_path(path) 
+        del path  # make sure we don't refer to path instead of self.path again 
+        absolute_path = self.get_absolute_path(self.root, self.path) 
+        self.absolute_path = self.validate_absolute_path( 
+            self.root, absolute_path) 
+        if self.absolute_path is None: 
+            return 
+ 
+        self.modified = self.get_modified_time() 
+        self.set_headers() 
+ 
+        if self.should_return_304(): 
+            self.set_status(304) 
+            return 
+ 
+        request_range = None 
+        range_header = self.request.headers.get("Range") 
+        if range_header: 
+            # As per RFC 2616 14.16, if an invalid Range header is specified, 
+            # the request will be treated as if the header didn't exist. 
+            request_range = httputil._parse_request_range(range_header) 
+ 
+        size = self.get_content_size() 
+        if request_range: 
+            start, end = request_range 
+            if (start is not None and start >= size) or end == 0: 
+                # As per RFC 2616 14.35.1, a range is not satisfiable only: if 
+                # the first requested byte is equal to or greater than the 
+                # content, or when a suffix with length 0 is specified 
+                self.set_status(416)  # Range Not Satisfiable 
+                self.set_header("Content-Type", "text/plain") 
+                self.set_header("Content-Range", "bytes */%s" % (size, )) 
+                return 
+            if start is not None and start < 0: 
+                start += size 
+            if end is not None and end > size: 
+                # Clients sometimes blindly use a large range to limit their 
+                # download size; cap the endpoint at the actual file size. 
+                end = size 
+            # Note: only return HTTP 206 if less than the entire range has been 
+            # requested. Not only is this semantically correct, but Chrome 
+            # refuses to play audio if it gets an HTTP 206 in response to 
+            # ``Range: bytes=0-``. 
+            if size != (end or size) - (start or 0): 
+                self.set_status(206)  # Partial Content 
+                self.set_header("Content-Range", 
+                                httputil._get_content_range(start, end, size)) 
+        else: 
+            start = end = None 
+ 
+        if start is not None and end is not None: 
+            content_length = end - start 
+        elif end is not None: 
+            content_length = end 
+        elif start is not None: 
+            content_length = size - start 
+        else: 
+            content_length = size 
+        self.set_header("Content-Length", content_length) 
+ 
+        if include_body: 
+            content = self.get_content(self.absolute_path, start, end) 
+            if isinstance(content, bytes): 
+                content = [content] 
+            for chunk in content: 
+                try: 
+                    self.write(chunk) 
+                    yield self.flush() 
+                except iostream.StreamClosedError: 
+                    return 
+        else: 
+            assert self.request.method == "HEAD" 
+ 
+    def compute_etag(self): 
+        """Sets the ``Etag`` header based on static url version. 
+ 
+        This allows efficient ``If-None-Match`` checks against cached 
+        versions, and sends the correct ``Etag`` for a partial response 
+        (i.e. the same ``Etag`` as the full file). 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        version_hash = self._get_cached_version(self.absolute_path) 
+        if not version_hash: 
+            return None 
+        return '"%s"' % (version_hash, ) 
+ 
+    def set_headers(self): 
+        """Sets the content and caching headers on the response. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        self.set_header("Accept-Ranges", "bytes") 
+        self.set_etag_header() 
+ 
+        if self.modified is not None: 
+            self.set_header("Last-Modified", self.modified) 
+ 
+        content_type = self.get_content_type() 
+        if content_type: 
+            self.set_header("Content-Type", content_type) 
+ 
+        cache_time = self.get_cache_time(self.path, self.modified, 
+                                         content_type) 
+        if cache_time > 0: 
+            self.set_header("Expires", datetime.datetime.utcnow() + 
+                            datetime.timedelta(seconds=cache_time)) 
+            self.set_header("Cache-Control", "max-age=" + str(cache_time)) 
+ 
+        self.set_extra_headers(self.path) 
+ 
+    def should_return_304(self): 
+        """Returns True if the headers indicate that we should return 304. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        if self.check_etag_header(): 
+            return True 
+ 
+        # Check the If-Modified-Since, and don't send the result if the 
+        # content has not been modified 
+        ims_value = self.request.headers.get("If-Modified-Since") 
+        if ims_value is not None: 
+            date_tuple = email.utils.parsedate(ims_value) 
+            if date_tuple is not None: 
+                if_since = datetime.datetime(*date_tuple[:6]) 
+                if if_since >= self.modified: 
+                    return True 
+ 
+        return False 
+ 
+    @classmethod 
+    def get_absolute_path(cls, root, path): 
+        """Returns the absolute location of ``path`` relative to ``root``. 
+ 
+        ``root`` is the path configured for this `StaticFileHandler` 
+        (in most cases the ``static_path`` `Application` setting). 
+ 
+        This class method may be overridden in subclasses.  By default 
+        it returns a filesystem path, but other strings may be used 
+        as long as they are unique and understood by the subclass's 
+        overridden `get_content`. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        abspath = os.path.abspath(os.path.join(root, path)) 
+        return abspath 
+ 
+    def validate_absolute_path(self, root, absolute_path): 
+        """Validate and return the absolute path. 
+ 
+        ``root`` is the configured path for the `StaticFileHandler`, 
+        and ``path`` is the result of `get_absolute_path` 
+ 
+        This is an instance method called during request processing, 
+        so it may raise `HTTPError` or use methods like 
+        `RequestHandler.redirect` (return None after redirecting to 
+        halt further processing).  This is where 404 errors for missing files 
+        are generated. 
+ 
+        This method may modify the path before returning it, but note that 
+        any such modifications will not be understood by `make_static_url`. 
+ 
+        In instance methods, this method's result is available as 
+        ``self.absolute_path``. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        # os.path.abspath strips a trailing /. 
+        # We must add it back to `root` so that we only match files 
+        # in a directory named `root` instead of files starting with 
+        # that prefix. 
+        root = os.path.abspath(root) 
+        if not root.endswith(os.path.sep): 
+            # abspath always removes a trailing slash, except when 
+            # root is '/'. This is an unusual case, but several projects 
+            # have independently discovered this technique to disable 
+            # Tornado's path validation and (hopefully) do their own, 
+            # so we need to support it. 
+            root += os.path.sep 
+        # The trailing slash also needs to be temporarily added back 
+        # the requested path so a request to root/ will match. 
+        if not (absolute_path + os.path.sep).startswith(root): 
+            raise HTTPError(403, "%s is not in root static directory", 
+                            self.path) 
+        if (os.path.isdir(absolute_path) and 
+                self.default_filename is not None): 
+            # need to look at the request.path here for when path is empty 
+            # but there is some prefix to the path that was already 
+            # trimmed by the routing 
+            if not self.request.path.endswith("/"): 
+                self.redirect(self.request.path + "/", permanent=True) 
+                return 
+            absolute_path = os.path.join(absolute_path, self.default_filename) 
+        if not os.path.exists(absolute_path): 
+            raise HTTPError(404) 
+        if not os.path.isfile(absolute_path): 
+            raise HTTPError(403, "%s is not a file", self.path) 
+        return absolute_path 
+ 
+    @classmethod 
+    def get_content(cls, abspath, start=None, end=None): 
+        """Retrieve the content of the requested resource which is located 
+        at the given absolute path. 
+ 
+        This class method may be overridden by subclasses.  Note that its 
+        signature is different from other overridable class methods 
+        (no ``settings`` argument); this is deliberate to ensure that 
+        ``abspath`` is able to stand on its own as a cache key. 
+ 
+        This method should either return a byte string or an iterator 
+        of byte strings.  The latter is preferred for large files 
+        as it helps reduce memory fragmentation. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        with open(abspath, "rb") as file: 
+            if start is not None: 
+                file.seek(start) 
+            if end is not None: 
+                remaining = end - (start or 0) 
+            else: 
+                remaining = None 
+            while True: 
+                chunk_size = 64 * 1024 
+                if remaining is not None and remaining < chunk_size: 
+                    chunk_size = remaining 
+                chunk = file.read(chunk_size) 
+                if chunk: 
+                    if remaining is not None: 
+                        remaining -= len(chunk) 
+                    yield chunk 
+                else: 
+                    if remaining is not None: 
+                        assert remaining == 0 
+                    return 
+ 
+    @classmethod 
+    def get_content_version(cls, abspath): 
+        """Returns a version string for the resource at the given path. 
+ 
+        This class method may be overridden by subclasses.  The 
+        default implementation is a hash of the file's contents. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        data = cls.get_content(abspath) 
+        hasher = hashlib.md5() 
+        if isinstance(data, bytes): 
+            hasher.update(data) 
+        else: 
+            for chunk in data: 
+                hasher.update(chunk) 
+        return hasher.hexdigest() 
+ 
+    def _stat(self): 
+        if not hasattr(self, '_stat_result'): 
+            self._stat_result = os.stat(self.absolute_path) 
+        return self._stat_result 
+ 
+    def get_content_size(self): 
+        """Retrieve the total size of the resource at the given path. 
+ 
+        This method may be overridden by subclasses. 
+ 
+        .. versionadded:: 3.1 
+ 
+        .. versionchanged:: 4.0 
+           This method is now always called, instead of only when 
+           partial results are requested. 
+        """ 
+        stat_result = self._stat() 
+        return stat_result[stat.ST_SIZE] 
+ 
+    def get_modified_time(self): 
+        """Returns the time that ``self.absolute_path`` was last modified. 
+ 
+        May be overridden in subclasses.  Should return a `~datetime.datetime` 
+        object or None. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        stat_result = self._stat() 
+        modified = datetime.datetime.utcfromtimestamp( 
+            stat_result[stat.ST_MTIME]) 
+        return modified 
+ 
+    def get_content_type(self): 
+        """Returns the ``Content-Type`` header to be used for this request. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        mime_type, encoding = mimetypes.guess_type(self.absolute_path) 
+        # per RFC 6713, use the appropriate type for a gzip compressed file 
+        if encoding == "gzip": 
+            return "application/gzip" 
+        # As of 2015-07-21 there is no bzip2 encoding defined at 
+        # http://www.iana.org/assignments/media-types/media-types.xhtml 
+        # So for that (and any other encoding), use octet-stream. 
+        elif encoding is not None: 
+            return "application/octet-stream" 
+        elif mime_type is not None: 
+            return mime_type 
+        # if mime_type not detected, use application/octet-stream 
+        else: 
+            return "application/octet-stream" 
+ 
+    def set_extra_headers(self, path): 
+        """For subclass to add extra headers to the response""" 
+        pass 
+ 
+    def get_cache_time(self, path, modified, mime_type): 
+        """Override to customize cache control behavior. 
+ 
+        Return a positive number of seconds to make the result 
+        cacheable for that amount of time or 0 to mark resource as 
+        cacheable for an unspecified amount of time (subject to 
+        browser heuristics). 
+ 
+        By default returns cache expiry of 10 years for resources requested 
+        with ``v`` argument. 
+        """ 
+        return self.CACHE_MAX_AGE if "v" in self.request.arguments else 0 
+ 
+    @classmethod 
+    def make_static_url(cls, settings, path, include_version=True): 
+        """Constructs a versioned url for the given path. 
+ 
+        This method may be overridden in subclasses (but note that it 
+        is a class method rather than an instance method).  Subclasses 
+        are only required to implement the signature 
+        ``make_static_url(cls, settings, path)``; other keyword 
+        arguments may be passed through `~RequestHandler.static_url` 
+        but are not standard. 
+ 
+        ``settings`` is the `Application.settings` dictionary.  ``path`` 
+        is the static path being requested.  The url returned should be 
+        relative to the current host. 
+ 
+        ``include_version`` determines whether the generated URL should 
+        include the query string containing the version hash of the 
+        file corresponding to the given ``path``. 
+ 
+        """ 
+        url = settings.get('static_url_prefix', '/static/') + path 
+        if not include_version: 
+            return url 
+ 
+        version_hash = cls.get_version(settings, path) 
+        if not version_hash: 
+            return url 
+ 
+        return '%s?v=%s' % (url, version_hash) 
+ 
+    def parse_url_path(self, url_path): 
+        """Converts a static URL path into a filesystem path. 
+ 
+        ``url_path`` is the path component of the URL with 
+        ``static_url_prefix`` removed.  The return value should be 
+        filesystem path relative to ``static_path``. 
+ 
+        This is the inverse of `make_static_url`. 
+        """ 
+        if os.path.sep != "/": 
+            url_path = url_path.replace("/", os.path.sep) 
+        return url_path 
+ 
+    @classmethod 
+    def get_version(cls, settings, path): 
+        """Generate the version string to be used in static URLs. 
+ 
+        ``settings`` is the `Application.settings` dictionary and ``path`` 
+        is the relative location of the requested asset on the filesystem. 
+        The returned value should be a string, or ``None`` if no version 
+        could be determined. 
+ 
+        .. versionchanged:: 3.1 
+           This method was previously recommended for subclasses to override; 
+           `get_content_version` is now preferred as it allows the base 
+           class to handle caching of the result. 
+        """ 
+        abs_path = cls.get_absolute_path(settings['static_path'], path) 
+        return cls._get_cached_version(abs_path) 
+ 
+    @classmethod 
+    def _get_cached_version(cls, abs_path): 
+        with cls._lock: 
+            hashes = cls._static_hashes 
+            if abs_path not in hashes: 
+                try: 
+                    hashes[abs_path] = cls.get_content_version(abs_path) 
+                except Exception: 
+                    gen_log.error("Could not open static file %r", abs_path) 
+                    hashes[abs_path] = None 
+            hsh = hashes.get(abs_path) 
+            if hsh: 
+                return hsh 
+        return None 
+ 
+ 
+class FallbackHandler(RequestHandler): 
+    """A `RequestHandler` that wraps another HTTP server callback. 
+ 
+    The fallback is a callable object that accepts an 
+    `~.httputil.HTTPServerRequest`, such as an `Application` or 
+    `tornado.wsgi.WSGIContainer`.  This is most useful to use both 
+    Tornado ``RequestHandlers`` and WSGI in the same server.  Typical 
+    usage:: 
+ 
+        wsgi_app = tornado.wsgi.WSGIContainer( 
+            django.core.handlers.wsgi.WSGIHandler()) 
+        application = tornado.web.Application([ 
+            (r"/foo", FooHandler), 
+            (r".*", FallbackHandler, dict(fallback=wsgi_app), 
+        ]) 
+    """ 
+    def initialize(self, fallback): 
+        self.fallback = fallback 
+ 
+    def prepare(self): 
+        self.fallback(self.request) 
+        self._finished = True 
+ 
+ 
+class OutputTransform(object): 
+    """A transform modifies the result of an HTTP request (e.g., GZip encoding) 
+ 
+    Applications are not expected to create their own OutputTransforms 
+    or interact with them directly; the framework chooses which transforms 
+    (if any) to apply. 
+    """ 
+    def __init__(self, request): 
+        pass 
+ 
+    def transform_first_chunk(self, status_code, headers, chunk, finishing): 
+        # type: (int, httputil.HTTPHeaders, bytes, bool) -> typing.Tuple[int, httputil.HTTPHeaders, bytes] 
+        return status_code, headers, chunk 
+ 
+    def transform_chunk(self, chunk, finishing): 
+        return chunk 
+ 
+ 
+class GZipContentEncoding(OutputTransform): 
+    """Applies the gzip content encoding to the response. 
+ 
+    See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.11 
+ 
+    .. versionchanged:: 4.0 
+        Now compresses all mime types beginning with ``text/``, instead 
+        of just a whitelist. (the whitelist is still used for certain 
+        non-text mime types). 
+    """ 
+    # Whitelist of compressible mime types (in addition to any types 
+    # beginning with "text/"). 
+    CONTENT_TYPES = set(["application/javascript", "application/x-javascript", 
+                         "application/xml", "application/atom+xml", 
+                         "application/json", "application/xhtml+xml", 
+                         "image/svg+xml"]) 
+    # Python's GzipFile defaults to level 9, while most other gzip 
+    # tools (including gzip itself) default to 6, which is probably a 
+    # better CPU/size tradeoff. 
+    GZIP_LEVEL = 6 
+    # Responses that are too short are unlikely to benefit from gzipping 
+    # after considering the "Content-Encoding: gzip" header and the header 
+    # inside the gzip encoding. 
+    # Note that responses written in multiple chunks will be compressed 
+    # regardless of size. 
+    MIN_LENGTH = 1024 
+ 
+    def __init__(self, request): 
+        self._gzipping = "gzip" in request.headers.get("Accept-Encoding", "") 
+ 
+    def _compressible_type(self, ctype): 
+        return ctype.startswith('text/') or ctype in self.CONTENT_TYPES 
+ 
+    def transform_first_chunk(self, status_code, headers, chunk, finishing): 
+        # type: (int, httputil.HTTPHeaders, bytes, bool) -> typing.Tuple[int, httputil.HTTPHeaders, bytes] 
+        # TODO: can/should this type be inherited from the superclass? 
+        if 'Vary' in headers: 
+            headers['Vary'] += ', Accept-Encoding' 
+        else: 
+            headers['Vary'] = 'Accept-Encoding' 
+        if self._gzipping: 
+            ctype = _unicode(headers.get("Content-Type", "")).split(";")[0] 
+            self._gzipping = self._compressible_type(ctype) and \ 
+                (not finishing or len(chunk) >= self.MIN_LENGTH) and \ 
+                ("Content-Encoding" not in headers) 
+        if self._gzipping: 
+            headers["Content-Encoding"] = "gzip" 
+            self._gzip_value = BytesIO() 
+            self._gzip_file = gzip.GzipFile(mode="w", fileobj=self._gzip_value, 
+                                            compresslevel=self.GZIP_LEVEL) 
+            chunk = self.transform_chunk(chunk, finishing) 
+            if "Content-Length" in headers: 
+                # The original content length is no longer correct. 
+                # If this is the last (and only) chunk, we can set the new 
+                # content-length; otherwise we remove it and fall back to 
+                # chunked encoding. 
+                if finishing: 
+                    headers["Content-Length"] = str(len(chunk)) 
+                else: 
+                    del headers["Content-Length"] 
+        return status_code, headers, chunk 
+ 
+    def transform_chunk(self, chunk, finishing): 
+        if self._gzipping: 
+            self._gzip_file.write(chunk) 
+            if finishing: 
+                self._gzip_file.close() 
+            else: 
+                self._gzip_file.flush() 
+            chunk = self._gzip_value.getvalue() 
+            self._gzip_value.truncate(0) 
+            self._gzip_value.seek(0) 
+        return chunk 
+ 
+ 
+def authenticated(method): 
+    """Decorate methods with this to require that the user be logged in. 
+ 
+    If the user is not logged in, they will be redirected to the configured 
+    `login url <RequestHandler.get_login_url>`. 
+ 
+    If you configure a login url with a query parameter, Tornado will 
+    assume you know what you're doing and use it as-is.  If not, it 
+    will add a `next` parameter so the login page knows where to send 
+    you once you're logged in. 
+    """ 
+    @functools.wraps(method) 
+    def wrapper(self, *args, **kwargs): 
+        if not self.current_user: 
+            if self.request.method in ("GET", "HEAD"): 
+                url = self.get_login_url() 
+                if "?" not in url: 
+                    if urlparse.urlsplit(url).scheme: 
+                        # if login url is absolute, make next absolute too 
+                        next_url = self.request.full_url() 
+                    else: 
+                        next_url = self.request.uri 
+                    url += "?" + urlencode(dict(next=next_url)) 
+                self.redirect(url) 
+                return 
+            raise HTTPError(403) 
+        return method(self, *args, **kwargs) 
+    return wrapper 
+ 
+ 
+class UIModule(object): 
+    """A re-usable, modular UI unit on a page. 
+ 
+    UI modules often execute additional queries, and they can include 
+    additional CSS and JavaScript that will be included in the output 
+    page, which is automatically inserted on page render. 
+ 
+    Subclasses of UIModule must override the `render` method. 
+    """ 
+    def __init__(self, handler): 
+        self.handler = handler 
+        self.request = handler.request 
+        self.ui = handler.ui 
+        self.locale = handler.locale 
+ 
+    @property 
+    def current_user(self): 
+        return self.handler.current_user 
+ 
+    def render(self, *args, **kwargs): 
+        """Override in subclasses to return this module's output.""" 
+        raise NotImplementedError() 
+ 
+    def embedded_javascript(self): 
+        """Override to return a JavaScript string 
+        to be embedded in the page.""" 
+        return None 
+ 
+    def javascript_files(self): 
+        """Override to return a list of JavaScript files needed by this module. 
+ 
+        If the return values are relative paths, they will be passed to 
+        `RequestHandler.static_url`; otherwise they will be used as-is. 
+        """ 
+        return None 
+ 
+    def embedded_css(self): 
+        """Override to return a CSS string 
+        that will be embedded in the page.""" 
+        return None 
+ 
+    def css_files(self): 
+        """Override to returns a list of CSS files required by this module. 
+ 
+        If the return values are relative paths, they will be passed to 
+        `RequestHandler.static_url`; otherwise they will be used as-is. 
+        """ 
+        return None 
+ 
+    def html_head(self): 
+        """Override to return an HTML string that will be put in the <head/> 
+        element. 
+        """ 
+        return None 
+ 
+    def html_body(self): 
+        """Override to return an HTML string that will be put at the end of 
+        the <body/> element. 
+        """ 
+        return None 
+ 
+    def render_string(self, path, **kwargs): 
+        """Renders a template and returns it as a string.""" 
+        return self.handler.render_string(path, **kwargs) 
+ 
+ 
+class _linkify(UIModule): 
+    def render(self, text, **kwargs): 
+        return escape.linkify(text, **kwargs) 
+ 
+ 
+class _xsrf_form_html(UIModule): 
+    def render(self): 
+        return self.handler.xsrf_form_html() 
+ 
+ 
+class TemplateModule(UIModule): 
+    """UIModule that simply renders the given template. 
+ 
+    {% module Template("foo.html") %} is similar to {% include "foo.html" %}, 
+    but the module version gets its own namespace (with kwargs passed to 
+    Template()) instead of inheriting the outer template's namespace. 
+ 
+    Templates rendered through this module also get access to UIModule's 
+    automatic javascript/css features.  Simply call set_resources 
+    inside the template and give it keyword arguments corresponding to 
+    the methods on UIModule: {{ set_resources(js_files=static_url("my.js")) }} 
+    Note that these resources are output once per template file, not once 
+    per instantiation of the template, so they must not depend on 
+    any arguments to the template. 
+    """ 
+    def __init__(self, handler): 
+        super(TemplateModule, self).__init__(handler) 
+        # keep resources in both a list and a dict to preserve order 
+        self._resource_list = [] 
+        self._resource_dict = {} 
+ 
+    def render(self, path, **kwargs): 
+        def set_resources(**kwargs): 
+            if path not in self._resource_dict: 
+                self._resource_list.append(kwargs) 
+                self._resource_dict[path] = kwargs 
+            else: 
+                if self._resource_dict[path] != kwargs: 
+                    raise ValueError("set_resources called with different " 
+                                     "resources for the same template") 
+            return "" 
+        return self.render_string(path, set_resources=set_resources, 
+                                  **kwargs) 
+ 
+    def _get_resources(self, key): 
+        return (r[key] for r in self._resource_list if key in r) 
+ 
+    def embedded_javascript(self): 
+        return "\n".join(self._get_resources("embedded_javascript")) 
+ 
+    def javascript_files(self): 
+        result = [] 
+        for f in self._get_resources("javascript_files"): 
+            if isinstance(f, (unicode_type, bytes)): 
+                result.append(f) 
+            else: 
+                result.extend(f) 
+        return result 
+ 
+    def embedded_css(self): 
+        return "\n".join(self._get_resources("embedded_css")) 
+ 
+    def css_files(self): 
+        result = [] 
+        for f in self._get_resources("css_files"): 
+            if isinstance(f, (unicode_type, bytes)): 
+                result.append(f) 
+            else: 
+                result.extend(f) 
+        return result 
+ 
+    def html_head(self): 
+        return "".join(self._get_resources("html_head")) 
+ 
+    def html_body(self): 
+        return "".join(self._get_resources("html_body")) 
+ 
+ 
+class _UIModuleNamespace(object): 
+    """Lazy namespace which creates UIModule proxies bound to a handler.""" 
+    def __init__(self, handler, ui_modules): 
+        self.handler = handler 
+        self.ui_modules = ui_modules 
+ 
+    def __getitem__(self, key): 
+        return self.handler._ui_module(key, self.ui_modules[key]) 
+ 
+    def __getattr__(self, key): 
+        try: 
+            return self[key] 
+        except KeyError as e: 
+            raise AttributeError(str(e)) 
+ 
+ 
+if hasattr(hmac, 'compare_digest'):  # python 3.3 
+    _time_independent_equals = hmac.compare_digest 
+else: 
+    def _time_independent_equals(a, b): 
+        if len(a) != len(b): 
+            return False 
+        result = 0 
+        if isinstance(a[0], int):  # python3 byte strings 
+            for x, y in zip(a, b): 
+                result |= x ^ y 
+        else:  # python2 
+            for x, y in zip(a, b): 
+                result |= ord(x) ^ ord(y) 
+        return result == 0 
+ 
+ 
+def create_signed_value(secret, name, value, version=None, clock=None, 
+                        key_version=None): 
+    if version is None: 
+        version = DEFAULT_SIGNED_VALUE_VERSION 
+    if clock is None: 
+        clock = time.time 
+ 
+    timestamp = utf8(str(int(clock()))) 
+    value = base64.b64encode(utf8(value)) 
+    if version == 1: 
+        signature = _create_signature_v1(secret, name, value, timestamp) 
+        value = b"|".join([value, timestamp, signature]) 
+        return value 
+    elif version == 2: 
+        # The v2 format consists of a version number and a series of 
+        # length-prefixed fields "%d:%s", the last of which is a 
+        # signature, all separated by pipes.  All numbers are in 
+        # decimal format with no leading zeros.  The signature is an 
+        # HMAC-SHA256 of the whole string up to that point, including 
+        # the final pipe. 
+        # 
+        # The fields are: 
+        # - format version (i.e. 2; no length prefix) 
+        # - key version (integer, default is 0) 
+        # - timestamp (integer seconds since epoch) 
+        # - name (not encoded; assumed to be ~alphanumeric) 
+        # - value (base64-encoded) 
+        # - signature (hex-encoded; no length prefix) 
+        def format_field(s): 
+            return utf8("%d:" % len(s)) + utf8(s) 
+        to_sign = b"|".join([ 
+            b"2", 
+            format_field(str(key_version or 0)), 
+            format_field(timestamp), 
+            format_field(name), 
+            format_field(value), 
+            b'']) 
+ 
+        if isinstance(secret, dict): 
+            assert key_version is not None, 'Key version must be set when sign key dict is used' 
+            assert version >= 2, 'Version must be at least 2 for key version support' 
+            secret = secret[key_version] 
+ 
+        signature = _create_signature_v2(secret, to_sign) 
+        return to_sign + signature 
+    else: 
+        raise ValueError("Unsupported version %d" % version) 
+ 
+ 
+# A leading version number in decimal 
+# with no leading zeros, followed by a pipe. 
+_signed_value_version_re = re.compile(br"^([1-9][0-9]*)\|(.*)$") 
+ 
+ 
+def _get_version(value): 
+    # Figures out what version value is.  Version 1 did not include an 
+    # explicit version field and started with arbitrary base64 data, 
+    # which makes this tricky. 
+    m = _signed_value_version_re.match(value) 
+    if m is None: 
+        version = 1 
+    else: 
+        try: 
+            version = int(m.group(1)) 
+            if version > 999: 
+                # Certain payloads from the version-less v1 format may 
+                # be parsed as valid integers.  Due to base64 padding 
+                # restrictions, this can only happen for numbers whose 
+                # length is a multiple of 4, so we can treat all 
+                # numbers up to 999 as versions, and for the rest we 
+                # fall back to v1 format. 
+                version = 1 
+        except ValueError: 
+            version = 1 
+    return version 
+ 
+ 
+def decode_signed_value(secret, name, value, max_age_days=31, 
+                        clock=None, min_version=None): 
+    if clock is None: 
+        clock = time.time 
+    if min_version is None: 
+        min_version = DEFAULT_SIGNED_VALUE_MIN_VERSION 
+    if min_version > 2: 
+        raise ValueError("Unsupported min_version %d" % min_version) 
+    if not value: 
+        return None 
+ 
+    value = utf8(value) 
+    version = _get_version(value) 
+ 
+    if version < min_version: 
+        return None 
+    if version == 1: 
+        return _decode_signed_value_v1(secret, name, value, 
+                                       max_age_days, clock) 
+    elif version == 2: 
+        return _decode_signed_value_v2(secret, name, value, 
+                                       max_age_days, clock) 
+    else: 
+        return None 
+ 
+ 
+def _decode_signed_value_v1(secret, name, value, max_age_days, clock): 
+    parts = utf8(value).split(b"|") 
+    if len(parts) != 3: 
+        return None 
+    signature = _create_signature_v1(secret, name, parts[0], parts[1]) 
+    if not _time_independent_equals(parts[2], signature): 
+        gen_log.warning("Invalid cookie signature %r", value) 
+        return None 
+    timestamp = int(parts[1]) 
+    if timestamp < clock() - max_age_days * 86400: 
+        gen_log.warning("Expired cookie %r", value) 
+        return None 
+    if timestamp > clock() + 31 * 86400: 
+        # _cookie_signature does not hash a delimiter between the 
+        # parts of the cookie, so an attacker could transfer trailing 
+        # digits from the payload to the timestamp without altering the 
+        # signature.  For backwards compatibility, sanity-check timestamp 
+        # here instead of modifying _cookie_signature. 
+        gen_log.warning("Cookie timestamp in future; possible tampering %r", 
+                        value) 
+        return None 
+    if parts[1].startswith(b"0"): 
+        gen_log.warning("Tampered cookie %r", value) 
+        return None 
+    try: 
+        return base64.b64decode(parts[0]) 
+    except Exception: 
+        return None 
+ 
+ 
+def _decode_fields_v2(value): 
+    def _consume_field(s): 
+        length, _, rest = s.partition(b':') 
+        n = int(length) 
+        field_value = rest[:n] 
+        # In python 3, indexing bytes returns small integers; we must 
+        # use a slice to get a byte string as in python 2. 
+        if rest[n:n + 1] != b'|': 
+            raise ValueError("malformed v2 signed value field") 
+        rest = rest[n + 1:] 
+        return field_value, rest 
+ 
+    rest = value[2:]  # remove version number 
+    key_version, rest = _consume_field(rest) 
+    timestamp, rest = _consume_field(rest) 
+    name_field, rest = _consume_field(rest) 
+    value_field, passed_sig = _consume_field(rest) 
+    return int(key_version), timestamp, name_field, value_field, passed_sig 
+ 
+ 
+def _decode_signed_value_v2(secret, name, value, max_age_days, clock): 
+    try: 
+        key_version, timestamp, name_field, value_field, passed_sig = _decode_fields_v2(value) 
+    except ValueError: 
+        return None 
+    signed_string = value[:-len(passed_sig)] 
+ 
+    if isinstance(secret, dict): 
+        try: 
+            secret = secret[key_version] 
+        except KeyError: 
+            return None 
+ 
+    expected_sig = _create_signature_v2(secret, signed_string) 
+    if not _time_independent_equals(passed_sig, expected_sig): 
+        return None 
+    if name_field != utf8(name): 
+        return None 
+    timestamp = int(timestamp) 
+    if timestamp < clock() - max_age_days * 86400: 
+        # The signature has expired. 
+        return None 
+    try: 
+        return base64.b64decode(value_field) 
+    except Exception: 
+        return None 
+ 
+ 
+def get_signature_key_version(value): 
+    value = utf8(value) 
+    version = _get_version(value) 
+    if version < 2: 
+        return None 
+    try: 
+        key_version, _, _, _, _ = _decode_fields_v2(value) 
+    except ValueError: 
+        return None 
+ 
+    return key_version 
+ 
+ 
+def _create_signature_v1(secret, *parts): 
+    hash = hmac.new(utf8(secret), digestmod=hashlib.sha1) 
+    for part in parts: 
+        hash.update(utf8(part)) 
+    return utf8(hash.hexdigest()) 
+ 
+ 
+def _create_signature_v2(secret, s): 
+    hash = hmac.new(utf8(secret), digestmod=hashlib.sha256) 
+    hash.update(utf8(s)) 
+    return utf8(hash.hexdigest()) 
+ 
+ 
+def is_absolute(path): 
+    return any(path.startswith(x) for x in ["/", "http:", "https:"]) 
diff --git a/contrib/python/tornado/tornado-4/tornado/websocket.py b/contrib/python/tornado/tornado-4/tornado/websocket.py
index 0e9d339f59..12086e116c 100644
--- a/contrib/python/tornado/tornado-4/tornado/websocket.py
+++ b/contrib/python/tornado/tornado-4/tornado/websocket.py
@@ -1,1244 +1,1244 @@
-"""Implementation of the WebSocket protocol.
-
-`WebSockets <http://dev.w3.org/html5/websockets/>`_ allow for bidirectional
-communication between the browser and server.
-
-WebSockets are supported in the current versions of all major browsers,
-although older versions that do not support WebSockets are still in use
-(refer to http://caniuse.com/websockets for details).
-
-This module implements the final version of the WebSocket protocol as
-defined in `RFC 6455 <http://tools.ietf.org/html/rfc6455>`_.  Certain
-browser versions (notably Safari 5.x) implemented an earlier draft of
-the protocol (known as "draft 76") and are not compatible with this module.
-
-.. versionchanged:: 4.0
-   Removed support for the draft 76 protocol version.
-"""
-
-from __future__ import absolute_import, division, print_function
-# Author: Jacob Kristhammar, 2010
-
-import base64
-import collections
-import hashlib
-import os
-import struct
-import tornado.escape
-import tornado.web
-import zlib
-
-from tornado.concurrent import TracebackFuture
-from tornado.escape import utf8, native_str, to_unicode
-from tornado import gen, httpclient, httputil
-from tornado.ioloop import IOLoop, PeriodicCallback
-from tornado.iostream import StreamClosedError
-from tornado.log import gen_log, app_log
-from tornado import simple_httpclient
-from tornado.tcpclient import TCPClient
-from tornado.util import _websocket_mask, PY3
-
-if PY3:
-    from urllib.parse import urlparse  # py2
-    xrange = range
-else:
-    from urlparse import urlparse  # py3
-
-
-class WebSocketError(Exception):
-    pass
-
-
-class WebSocketClosedError(WebSocketError):
-    """Raised by operations on a closed connection.
-
-    .. versionadded:: 3.2
-    """
-    pass
-
-
-class WebSocketHandler(tornado.web.RequestHandler):
-    """Subclass this class to create a basic WebSocket handler.
-
-    Override `on_message` to handle incoming messages, and use
-    `write_message` to send messages to the client. You can also
-    override `open` and `on_close` to handle opened and closed
-    connections.
-
-    Custom upgrade response headers can be sent by overriding
-    `~tornado.web.RequestHandler.set_default_headers` or
-    `~tornado.web.RequestHandler.prepare`.
-
-    See http://dev.w3.org/html5/websockets/ for details on the
-    JavaScript interface.  The protocol is specified at
-    http://tools.ietf.org/html/rfc6455.
-
-    Here is an example WebSocket handler that echos back all received messages
-    back to the client:
-
-    .. testcode::
-
-      class EchoWebSocket(tornado.websocket.WebSocketHandler):
-          def open(self):
-              print("WebSocket opened")
-
-          def on_message(self, message):
-              self.write_message(u"You said: " + message)
-
-          def on_close(self):
-              print("WebSocket closed")
-
-    .. testoutput::
-       :hide:
-
-    WebSockets are not standard HTTP connections. The "handshake" is
-    HTTP, but after the handshake, the protocol is
-    message-based. Consequently, most of the Tornado HTTP facilities
-    are not available in handlers of this type. The only communication
-    methods available to you are `write_message()`, `ping()`, and
-    `close()`. Likewise, your request handler class should implement
-    `open()` method rather than ``get()`` or ``post()``.
-
-    If you map the handler above to ``/websocket`` in your application, you can
-    invoke it in JavaScript with::
-
-      var ws = new WebSocket("ws://localhost:8888/websocket");
-      ws.onopen = function() {
-         ws.send("Hello, world");
-      };
-      ws.onmessage = function (evt) {
-         alert(evt.data);
-      };
-
-    This script pops up an alert box that says "You said: Hello, world".
-
-    Web browsers allow any site to open a websocket connection to any other,
-    instead of using the same-origin policy that governs other network
-    access from javascript.  This can be surprising and is a potential
-    security hole, so since Tornado 4.0 `WebSocketHandler` requires
-    applications that wish to receive cross-origin websockets to opt in
-    by overriding the `~WebSocketHandler.check_origin` method (see that
-    method's docs for details).  Failure to do so is the most likely
-    cause of 403 errors when making a websocket connection.
-
-    When using a secure websocket connection (``wss://``) with a self-signed
-    certificate, the connection from a browser may fail because it wants
-    to show the "accept this certificate" dialog but has nowhere to show it.
-    You must first visit a regular HTML page using the same certificate
-    to accept it before the websocket connection will succeed.
-
-    If the application setting ``websocket_ping_interval`` has a non-zero
-    value, a ping will be sent periodically, and the connection will be
-    closed if a response is not received before the ``websocket_ping_timeout``.
-
-    Messages larger than the ``websocket_max_message_size`` application setting
-    (default 10MiB) will not be accepted.
-
-    .. versionchanged:: 4.5
-       Added ``websocket_ping_interval``, ``websocket_ping_timeout``, and
-       ``websocket_max_message_size``.
-    """
-    def __init__(self, application, request, **kwargs):
-        super(WebSocketHandler, self).__init__(application, request, **kwargs)
-        self.ws_connection = None
-        self.close_code = None
-        self.close_reason = None
-        self.stream = None
-        self._on_close_called = False
-
-    @tornado.web.asynchronous
-    def get(self, *args, **kwargs):
-        self.open_args = args
-        self.open_kwargs = kwargs
-
-        # Upgrade header should be present and should be equal to WebSocket
-        if self.request.headers.get("Upgrade", "").lower() != 'websocket':
-            self.set_status(400)
-            log_msg = "Can \"Upgrade\" only to \"WebSocket\"."
-            self.finish(log_msg)
-            gen_log.debug(log_msg)
-            return
-
-        # Connection header should be upgrade.
-        # Some proxy servers/load balancers
-        # might mess with it.
-        headers = self.request.headers
-        connection = map(lambda s: s.strip().lower(),
-                         headers.get("Connection", "").split(","))
-        if 'upgrade' not in connection:
-            self.set_status(400)
-            log_msg = "\"Connection\" must be \"Upgrade\"."
-            self.finish(log_msg)
-            gen_log.debug(log_msg)
-            return
-
-        # Handle WebSocket Origin naming convention differences
-        # The difference between version 8 and 13 is that in 8 the
-        # client sends a "Sec-Websocket-Origin" header and in 13 it's
-        # simply "Origin".
-        if "Origin" in self.request.headers:
-            origin = self.request.headers.get("Origin")
-        else:
-            origin = self.request.headers.get("Sec-Websocket-Origin", None)
-
-        # If there was an origin header, check to make sure it matches
-        # according to check_origin. When the origin is None, we assume it
-        # did not come from a browser and that it can be passed on.
-        if origin is not None and not self.check_origin(origin):
-            self.set_status(403)
-            log_msg = "Cross origin websockets not allowed"
-            self.finish(log_msg)
-            gen_log.debug(log_msg)
-            return
-
-        self.ws_connection = self.get_websocket_protocol()
-        if self.ws_connection:
-            self.ws_connection.accept_connection()
-        else:
-            self.set_status(426, "Upgrade Required")
-            self.set_header("Sec-WebSocket-Version", "7, 8, 13")
-            self.finish()
-
-    stream = None
-
-    @property
-    def ping_interval(self):
-        """The interval for websocket keep-alive pings.
-
-        Set websocket_ping_interval = 0 to disable pings.
-        """
-        return self.settings.get('websocket_ping_interval', None)
-
-    @property
-    def ping_timeout(self):
-        """If no ping is received in this many seconds,
-        close the websocket connection (VPNs, etc. can fail to cleanly close ws connections).
-        Default is max of 3 pings or 30 seconds.
-        """
-        return self.settings.get('websocket_ping_timeout', None)
-
-    @property
-    def max_message_size(self):
-        """Maximum allowed message size.
-
-        If the remote peer sends a message larger than this, the connection
-        will be closed.
-
-        Default is 10MiB.
-        """
-        return self.settings.get('websocket_max_message_size', None)
-
-    def write_message(self, message, binary=False):
-        """Sends the given message to the client of this Web Socket.
-
-        The message may be either a string or a dict (which will be
-        encoded as json).  If the ``binary`` argument is false, the
-        message will be sent as utf8; in binary mode any byte string
-        is allowed.
-
-        If the connection is already closed, raises `WebSocketClosedError`.
-
-        .. versionchanged:: 3.2
-           `WebSocketClosedError` was added (previously a closed connection
-           would raise an `AttributeError`)
-
-        .. versionchanged:: 4.3
-           Returns a `.Future` which can be used for flow control.
-        """
-        if self.ws_connection is None:
-            raise WebSocketClosedError()
-        if isinstance(message, dict):
-            message = tornado.escape.json_encode(message)
-        return self.ws_connection.write_message(message, binary=binary)
-
-    def select_subprotocol(self, subprotocols):
-        """Invoked when a new WebSocket requests specific subprotocols.
-
-        ``subprotocols`` is a list of strings identifying the
-        subprotocols proposed by the client.  This method may be
-        overridden to return one of those strings to select it, or
-        ``None`` to not select a subprotocol.  Failure to select a
-        subprotocol does not automatically abort the connection,
-        although clients may close the connection if none of their
-        proposed subprotocols was selected.
-        """
-        return None
-
-    def get_compression_options(self):
-        """Override to return compression options for the connection.
-
-        If this method returns None (the default), compression will
-        be disabled.  If it returns a dict (even an empty one), it
-        will be enabled.  The contents of the dict may be used to
-        control the following compression options:
-
-        ``compression_level`` specifies the compression level.
-
-        ``mem_level`` specifies the amount of memory used for the internal compression state.
-
-         These parameters are documented in details here:
-         https://docs.python.org/3.6/library/zlib.html#zlib.compressobj
-
-        .. versionadded:: 4.1
-
-        .. versionchanged:: 4.5
-
-           Added ``compression_level`` and ``mem_level``.
-        """
-        # TODO: Add wbits option.
-        return None
-
-    def open(self, *args, **kwargs):
-        """Invoked when a new WebSocket is opened.
-
-        The arguments to `open` are extracted from the `tornado.web.URLSpec`
-        regular expression, just like the arguments to
-        `tornado.web.RequestHandler.get`.
-        """
-        pass
-
-    def on_message(self, message):
-        """Handle incoming messages on the WebSocket
-
-        This method must be overridden.
-
-        .. versionchanged:: 4.5
-
-           ``on_message`` can be a coroutine.
-        """
-        raise NotImplementedError
-
-    def ping(self, data):
-        """Send ping frame to the remote end."""
-        if self.ws_connection is None:
-            raise WebSocketClosedError()
-        self.ws_connection.write_ping(data)
-
-    def on_pong(self, data):
-        """Invoked when the response to a ping frame is received."""
-        pass
-
-    def on_ping(self, data):
-        """Invoked when the a ping frame is received."""
-        pass
-
-    def on_close(self):
-        """Invoked when the WebSocket is closed.
-
-        If the connection was closed cleanly and a status code or reason
-        phrase was supplied, these values will be available as the attributes
-        ``self.close_code`` and ``self.close_reason``.
-
-        .. versionchanged:: 4.0
-
-           Added ``close_code`` and ``close_reason`` attributes.
-        """
-        pass
-
-    def close(self, code=None, reason=None):
-        """Closes this Web Socket.
-
-        Once the close handshake is successful the socket will be closed.
-
-        ``code`` may be a numeric status code, taken from the values
-        defined in `RFC 6455 section 7.4.1
-        <https://tools.ietf.org/html/rfc6455#section-7.4.1>`_.
-        ``reason`` may be a textual message about why the connection is
-        closing.  These values are made available to the client, but are
-        not otherwise interpreted by the websocket protocol.
-
-        .. versionchanged:: 4.0
-
-           Added the ``code`` and ``reason`` arguments.
-        """
-        if self.ws_connection:
-            self.ws_connection.close(code, reason)
-            self.ws_connection = None
-
-    def check_origin(self, origin):
-        """Override to enable support for allowing alternate origins.
-
-        The ``origin`` argument is the value of the ``Origin`` HTTP
-        header, the url responsible for initiating this request.  This
-        method is not called for clients that do not send this header;
-        such requests are always allowed (because all browsers that
-        implement WebSockets support this header, and non-browser
-        clients do not have the same cross-site security concerns).
-
-        Should return True to accept the request or False to reject it.
-        By default, rejects all requests with an origin on a host other
-        than this one.
-
-        This is a security protection against cross site scripting attacks on
-        browsers, since WebSockets are allowed to bypass the usual same-origin
-        policies and don't use CORS headers.
-
-        .. warning::
-
-           This is an important security measure; don't disable it
-           without understanding the security implications. In
-           particular, if your authentication is cookie-based, you
-           must either restrict the origins allowed by
-           ``check_origin()`` or implement your own XSRF-like
-           protection for websocket connections. See `these
-           <https://www.christian-schneider.net/CrossSiteWebSocketHijacking.html>`_
-           `articles
-           <https://devcenter.heroku.com/articles/websocket-security>`_
-           for more.
-
-        To accept all cross-origin traffic (which was the default prior to
-        Tornado 4.0), simply override this method to always return true::
-
-            def check_origin(self, origin):
-                return True
-
-        To allow connections from any subdomain of your site, you might
-        do something like::
-
-            def check_origin(self, origin):
-                parsed_origin = urllib.parse.urlparse(origin)
-                return parsed_origin.netloc.endswith(".mydomain.com")
-
-        .. versionadded:: 4.0
-
-        """
-        parsed_origin = urlparse(origin)
-        origin = parsed_origin.netloc
-        origin = origin.lower()
-
-        host = self.request.headers.get("Host")
-
-        # Check to see that origin matches host directly, including ports
-        return origin == host
-
-    def set_nodelay(self, value):
-        """Set the no-delay flag for this stream.
-
-        By default, small messages may be delayed and/or combined to minimize
-        the number of packets sent.  This can sometimes cause 200-500ms delays
-        due to the interaction between Nagle's algorithm and TCP delayed
-        ACKs.  To reduce this delay (at the expense of possibly increasing
-        bandwidth usage), call ``self.set_nodelay(True)`` once the websocket
-        connection is established.
-
-        See `.BaseIOStream.set_nodelay` for additional details.
-
-        .. versionadded:: 3.1
-        """
-        self.stream.set_nodelay(value)
-
-    def on_connection_close(self):
-        if self.ws_connection:
-            self.ws_connection.on_connection_close()
-            self.ws_connection = None
-        if not self._on_close_called:
-            self._on_close_called = True
-            self.on_close()
-            self._break_cycles()
-
-    def _break_cycles(self):
-        # WebSocketHandlers call finish() early, but we don't want to
-        # break up reference cycles (which makes it impossible to call
-        # self.render_string) until after we've really closed the
-        # connection (if it was established in the first place,
-        # indicated by status code 101).
-        if self.get_status() != 101 or self._on_close_called:
-            super(WebSocketHandler, self)._break_cycles()
-
-    def send_error(self, *args, **kwargs):
-        if self.stream is None:
-            super(WebSocketHandler, self).send_error(*args, **kwargs)
-        else:
-            # If we get an uncaught exception during the handshake,
-            # we have no choice but to abruptly close the connection.
-            # TODO: for uncaught exceptions after the handshake,
-            # we can close the connection more gracefully.
-            self.stream.close()
-
-    def get_websocket_protocol(self):
-        websocket_version = self.request.headers.get("Sec-WebSocket-Version")
-        if websocket_version in ("7", "8", "13"):
-            return WebSocketProtocol13(
-                self, compression_options=self.get_compression_options())
-
-    def _attach_stream(self):
-        self.stream = self.request.connection.detach()
-        self.stream.set_close_callback(self.on_connection_close)
-        # disable non-WS methods
-        for method in ["write", "redirect", "set_header", "set_cookie",
-                       "set_status", "flush", "finish"]:
-            setattr(self, method, _raise_not_supported_for_websockets)
-
-
-def _raise_not_supported_for_websockets(*args, **kwargs):
-    raise RuntimeError("Method not supported for Web Sockets")
-
-
-class WebSocketProtocol(object):
-    """Base class for WebSocket protocol versions.
-    """
-    def __init__(self, handler):
-        self.handler = handler
-        self.request = handler.request
-        self.stream = handler.stream
-        self.client_terminated = False
-        self.server_terminated = False
-
-    def _run_callback(self, callback, *args, **kwargs):
-        """Runs the given callback with exception handling.
-
-        If the callback is a coroutine, returns its Future. On error, aborts the
-        websocket connection and returns None.
-        """
-        try:
-            result = callback(*args, **kwargs)
-        except Exception:
-            app_log.error("Uncaught exception in %s",
-                          getattr(self.request, 'path', None), exc_info=True)
-            self._abort()
-        else:
-            if result is not None:
-                result = gen.convert_yielded(result)
-                self.stream.io_loop.add_future(result, lambda f: f.result())
-            return result
-
-    def on_connection_close(self):
-        self._abort()
-
-    def _abort(self):
-        """Instantly aborts the WebSocket connection by closing the socket"""
-        self.client_terminated = True
-        self.server_terminated = True
-        self.stream.close()  # forcibly tear down the connection
-        self.close()  # let the subclass cleanup
-
-
-class _PerMessageDeflateCompressor(object):
-    def __init__(self, persistent, max_wbits, compression_options=None):
-        if max_wbits is None:
-            max_wbits = zlib.MAX_WBITS
-        # There is no symbolic constant for the minimum wbits value.
-        if not (8 <= max_wbits <= zlib.MAX_WBITS):
-            raise ValueError("Invalid max_wbits value %r; allowed range 8-%d",
-                             max_wbits, zlib.MAX_WBITS)
-        self._max_wbits = max_wbits
-
-        if compression_options is None or 'compression_level' not in compression_options:
-            self._compression_level = tornado.web.GZipContentEncoding.GZIP_LEVEL
-        else:
-            self._compression_level = compression_options['compression_level']
-
-        if compression_options is None or 'mem_level' not in compression_options:
-            self._mem_level = 8
-        else:
-            self._mem_level = compression_options['mem_level']
-
-        if persistent:
-            self._compressor = self._create_compressor()
-        else:
-            self._compressor = None
-
-    def _create_compressor(self):
-        return zlib.compressobj(self._compression_level, zlib.DEFLATED, -self._max_wbits, self._mem_level)
-
-    def compress(self, data):
-        compressor = self._compressor or self._create_compressor()
-        data = (compressor.compress(data) +
-                compressor.flush(zlib.Z_SYNC_FLUSH))
-        assert data.endswith(b'\x00\x00\xff\xff')
-        return data[:-4]
-
-
-class _PerMessageDeflateDecompressor(object):
-    def __init__(self, persistent, max_wbits, compression_options=None):
-        if max_wbits is None:
-            max_wbits = zlib.MAX_WBITS
-        if not (8 <= max_wbits <= zlib.MAX_WBITS):
-            raise ValueError("Invalid max_wbits value %r; allowed range 8-%d",
-                             max_wbits, zlib.MAX_WBITS)
-        self._max_wbits = max_wbits
-        if persistent:
-            self._decompressor = self._create_decompressor()
-        else:
-            self._decompressor = None
-
-    def _create_decompressor(self):
-        return zlib.decompressobj(-self._max_wbits)
-
-    def decompress(self, data):
-        decompressor = self._decompressor or self._create_decompressor()
-        return decompressor.decompress(data + b'\x00\x00\xff\xff')
-
-
-class WebSocketProtocol13(WebSocketProtocol):
-    """Implementation of the WebSocket protocol from RFC 6455.
-
-    This class supports versions 7 and 8 of the protocol in addition to the
-    final version 13.
-    """
-    # Bit masks for the first byte of a frame.
-    FIN = 0x80
-    RSV1 = 0x40
-    RSV2 = 0x20
-    RSV3 = 0x10
-    RSV_MASK = RSV1 | RSV2 | RSV3
-    OPCODE_MASK = 0x0f
-
-    def __init__(self, handler, mask_outgoing=False,
-                 compression_options=None):
-        WebSocketProtocol.__init__(self, handler)
-        self.mask_outgoing = mask_outgoing
-        self._final_frame = False
-        self._frame_opcode = None
-        self._masked_frame = None
-        self._frame_mask = None
-        self._frame_length = None
-        self._fragmented_message_buffer = None
-        self._fragmented_message_opcode = None
-        self._waiting = None
-        self._compression_options = compression_options
-        self._decompressor = None
-        self._compressor = None
-        self._frame_compressed = None
-        # The total uncompressed size of all messages received or sent.
-        # Unicode messages are encoded to utf8.
-        # Only for testing; subject to change.
-        self._message_bytes_in = 0
-        self._message_bytes_out = 0
-        # The total size of all packets received or sent.  Includes
-        # the effect of compression, frame overhead, and control frames.
-        self._wire_bytes_in = 0
-        self._wire_bytes_out = 0
-        self.ping_callback = None
-        self.last_ping = 0
-        self.last_pong = 0
-
-    def accept_connection(self):
-        try:
-            self._handle_websocket_headers()
-        except ValueError:
-            self.handler.set_status(400)
-            log_msg = "Missing/Invalid WebSocket headers"
-            self.handler.finish(log_msg)
-            gen_log.debug(log_msg)
-            return
-
-        try:
-            self._accept_connection()
-        except ValueError:
-            gen_log.debug("Malformed WebSocket request received",
-                          exc_info=True)
-            self._abort()
-            return
-
-    def _handle_websocket_headers(self):
-        """Verifies all invariant- and required headers
-
-        If a header is missing or have an incorrect value ValueError will be
-        raised
-        """
-        fields = ("Host", "Sec-Websocket-Key", "Sec-Websocket-Version")
-        if not all(map(lambda f: self.request.headers.get(f), fields)):
-            raise ValueError("Missing/Invalid WebSocket headers")
-
-    @staticmethod
-    def compute_accept_value(key):
-        """Computes the value for the Sec-WebSocket-Accept header,
-        given the value for Sec-WebSocket-Key.
-        """
-        sha1 = hashlib.sha1()
-        sha1.update(utf8(key))
-        sha1.update(b"258EAFA5-E914-47DA-95CA-C5AB0DC85B11")  # Magic value
-        return native_str(base64.b64encode(sha1.digest()))
-
-    def _challenge_response(self):
-        return WebSocketProtocol13.compute_accept_value(
-            self.request.headers.get("Sec-Websocket-Key"))
-
-    def _accept_connection(self):
-        subprotocols = self.request.headers.get("Sec-WebSocket-Protocol", '')
-        subprotocols = [s.strip() for s in subprotocols.split(',')]
-        if subprotocols:
-            selected = self.handler.select_subprotocol(subprotocols)
-            if selected:
-                assert selected in subprotocols
-                self.handler.set_header("Sec-WebSocket-Protocol", selected)
-
-        extensions = self._parse_extensions_header(self.request.headers)
-        for ext in extensions:
-            if (ext[0] == 'permessage-deflate' and
-                    self._compression_options is not None):
-                # TODO: negotiate parameters if compression_options
-                # specifies limits.
-                self._create_compressors('server', ext[1], self._compression_options)
-                if ('client_max_window_bits' in ext[1] and
-                        ext[1]['client_max_window_bits'] is None):
-                    # Don't echo an offered client_max_window_bits
-                    # parameter with no value.
-                    del ext[1]['client_max_window_bits']
-                self.handler.set_header("Sec-WebSocket-Extensions",
-                                        httputil._encode_header(
-                                            'permessage-deflate', ext[1]))
-                break
-
-        self.handler.clear_header("Content-Type")
-        self.handler.set_status(101)
-        self.handler.set_header("Upgrade", "websocket")
-        self.handler.set_header("Connection", "Upgrade")
-        self.handler.set_header("Sec-WebSocket-Accept", self._challenge_response())
-        self.handler.finish()
-
-        self.handler._attach_stream()
-        self.stream = self.handler.stream
-
-        self.start_pinging()
-        self._run_callback(self.handler.open, *self.handler.open_args,
-                           **self.handler.open_kwargs)
-        self._receive_frame()
-
-    def _parse_extensions_header(self, headers):
-        extensions = headers.get("Sec-WebSocket-Extensions", '')
-        if extensions:
-            return [httputil._parse_header(e.strip())
-                    for e in extensions.split(',')]
-        return []
-
-    def _process_server_headers(self, key, headers):
-        """Process the headers sent by the server to this client connection.
-
-        'key' is the websocket handshake challenge/response key.
-        """
-        assert headers['Upgrade'].lower() == 'websocket'
-        assert headers['Connection'].lower() == 'upgrade'
-        accept = self.compute_accept_value(key)
-        assert headers['Sec-Websocket-Accept'] == accept
-
-        extensions = self._parse_extensions_header(headers)
-        for ext in extensions:
-            if (ext[0] == 'permessage-deflate' and
-                    self._compression_options is not None):
-                self._create_compressors('client', ext[1])
-            else:
-                raise ValueError("unsupported extension %r", ext)
-
-    def _get_compressor_options(self, side, agreed_parameters, compression_options=None):
-        """Converts a websocket agreed_parameters set to keyword arguments
-        for our compressor objects.
-        """
-        options = dict(
-            persistent=(side + '_no_context_takeover') not in agreed_parameters)
-        wbits_header = agreed_parameters.get(side + '_max_window_bits', None)
-        if wbits_header is None:
-            options['max_wbits'] = zlib.MAX_WBITS
-        else:
-            options['max_wbits'] = int(wbits_header)
-        options['compression_options'] = compression_options
-        return options
-
-    def _create_compressors(self, side, agreed_parameters, compression_options=None):
-        # TODO: handle invalid parameters gracefully
-        allowed_keys = set(['server_no_context_takeover',
-                            'client_no_context_takeover',
-                            'server_max_window_bits',
-                            'client_max_window_bits'])
-        for key in agreed_parameters:
-            if key not in allowed_keys:
-                raise ValueError("unsupported compression parameter %r" % key)
-        other_side = 'client' if (side == 'server') else 'server'
-        self._compressor = _PerMessageDeflateCompressor(
-            **self._get_compressor_options(side, agreed_parameters, compression_options))
-        self._decompressor = _PerMessageDeflateDecompressor(
-            **self._get_compressor_options(other_side, agreed_parameters, compression_options))
-
-    def _write_frame(self, fin, opcode, data, flags=0):
-        if fin:
-            finbit = self.FIN
-        else:
-            finbit = 0
-        frame = struct.pack("B", finbit | opcode | flags)
-        l = len(data)
-        if self.mask_outgoing:
-            mask_bit = 0x80
-        else:
-            mask_bit = 0
-        if l < 126:
-            frame += struct.pack("B", l | mask_bit)
-        elif l <= 0xFFFF:
-            frame += struct.pack("!BH", 126 | mask_bit, l)
-        else:
-            frame += struct.pack("!BQ", 127 | mask_bit, l)
-        if self.mask_outgoing:
-            mask = os.urandom(4)
-            data = mask + _websocket_mask(mask, data)
-        frame += data
-        self._wire_bytes_out += len(frame)
-        try:
-            return self.stream.write(frame)
-        except StreamClosedError:
-            self._abort()
-
-    def write_message(self, message, binary=False):
-        """Sends the given message to the client of this Web Socket."""
-        if binary:
-            opcode = 0x2
-        else:
-            opcode = 0x1
-        message = tornado.escape.utf8(message)
-        assert isinstance(message, bytes)
-        self._message_bytes_out += len(message)
-        flags = 0
-        if self._compressor:
-            message = self._compressor.compress(message)
-            flags |= self.RSV1
-        return self._write_frame(True, opcode, message, flags=flags)
-
-    def write_ping(self, data):
-        """Send ping frame."""
-        assert isinstance(data, bytes)
-        self._write_frame(True, 0x9, data)
-
-    def _receive_frame(self):
-        try:
-            self.stream.read_bytes(2, self._on_frame_start)
-        except StreamClosedError:
-            self._abort()
-
-    def _on_frame_start(self, data):
-        self._wire_bytes_in += len(data)
-        header, payloadlen = struct.unpack("BB", data)
-        self._final_frame = header & self.FIN
-        reserved_bits = header & self.RSV_MASK
-        self._frame_opcode = header & self.OPCODE_MASK
-        self._frame_opcode_is_control = self._frame_opcode & 0x8
-        if self._decompressor is not None and self._frame_opcode != 0:
-            self._frame_compressed = bool(reserved_bits & self.RSV1)
-            reserved_bits &= ~self.RSV1
-        if reserved_bits:
-            # client is using as-yet-undefined extensions; abort
-            self._abort()
-            return
-        self._masked_frame = bool(payloadlen & 0x80)
-        payloadlen = payloadlen & 0x7f
-        if self._frame_opcode_is_control and payloadlen >= 126:
-            # control frames must have payload < 126
-            self._abort()
-            return
-        try:
-            if payloadlen < 126:
-                self._frame_length = payloadlen
-                if self._masked_frame:
-                    self.stream.read_bytes(4, self._on_masking_key)
-                else:
-                    self._read_frame_data(False)
-            elif payloadlen == 126:
-                self.stream.read_bytes(2, self._on_frame_length_16)
-            elif payloadlen == 127:
-                self.stream.read_bytes(8, self._on_frame_length_64)
-        except StreamClosedError:
-            self._abort()
-
-    def _read_frame_data(self, masked):
-        new_len = self._frame_length
-        if self._fragmented_message_buffer is not None:
-            new_len += len(self._fragmented_message_buffer)
-        if new_len > (self.handler.max_message_size or 10 * 1024 * 1024):
-            self.close(1009, "message too big")
-            return
-        self.stream.read_bytes(
-            self._frame_length,
-            self._on_masked_frame_data if masked else self._on_frame_data)
-
-    def _on_frame_length_16(self, data):
-        self._wire_bytes_in += len(data)
-        self._frame_length = struct.unpack("!H", data)[0]
-        try:
-            if self._masked_frame:
-                self.stream.read_bytes(4, self._on_masking_key)
-            else:
-                self._read_frame_data(False)
-        except StreamClosedError:
-            self._abort()
-
-    def _on_frame_length_64(self, data):
-        self._wire_bytes_in += len(data)
-        self._frame_length = struct.unpack("!Q", data)[0]
-        try:
-            if self._masked_frame:
-                self.stream.read_bytes(4, self._on_masking_key)
-            else:
-                self._read_frame_data(False)
-        except StreamClosedError:
-            self._abort()
-
-    def _on_masking_key(self, data):
-        self._wire_bytes_in += len(data)
-        self._frame_mask = data
-        try:
-            self._read_frame_data(True)
-        except StreamClosedError:
-            self._abort()
-
-    def _on_masked_frame_data(self, data):
-        # Don't touch _wire_bytes_in; we'll do it in _on_frame_data.
-        self._on_frame_data(_websocket_mask(self._frame_mask, data))
-
-    def _on_frame_data(self, data):
-        handled_future = None
-
-        self._wire_bytes_in += len(data)
-        if self._frame_opcode_is_control:
-            # control frames may be interleaved with a series of fragmented
-            # data frames, so control frames must not interact with
-            # self._fragmented_*
-            if not self._final_frame:
-                # control frames must not be fragmented
-                self._abort()
-                return
-            opcode = self._frame_opcode
-        elif self._frame_opcode == 0:  # continuation frame
-            if self._fragmented_message_buffer is None:
-                # nothing to continue
-                self._abort()
-                return
-            self._fragmented_message_buffer += data
-            if self._final_frame:
-                opcode = self._fragmented_message_opcode
-                data = self._fragmented_message_buffer
-                self._fragmented_message_buffer = None
-        else:  # start of new data message
-            if self._fragmented_message_buffer is not None:
-                # can't start new message until the old one is finished
-                self._abort()
-                return
-            if self._final_frame:
-                opcode = self._frame_opcode
-            else:
-                self._fragmented_message_opcode = self._frame_opcode
-                self._fragmented_message_buffer = data
-
-        if self._final_frame:
-            handled_future = self._handle_message(opcode, data)
-
-        if not self.client_terminated:
-            if handled_future:
-                # on_message is a coroutine, process more frames once it's done.
-                handled_future.add_done_callback(
-                    lambda future: self._receive_frame())
-            else:
-                self._receive_frame()
-
-    def _handle_message(self, opcode, data):
-        """Execute on_message, returning its Future if it is a coroutine."""
-        if self.client_terminated:
-            return
-
-        if self._frame_compressed:
-            data = self._decompressor.decompress(data)
-
-        if opcode == 0x1:
-            # UTF-8 data
-            self._message_bytes_in += len(data)
-            try:
-                decoded = data.decode("utf-8")
-            except UnicodeDecodeError:
-                self._abort()
-                return
-            return self._run_callback(self.handler.on_message, decoded)
-        elif opcode == 0x2:
-            # Binary data
-            self._message_bytes_in += len(data)
-            return self._run_callback(self.handler.on_message, data)
-        elif opcode == 0x8:
-            # Close
-            self.client_terminated = True
-            if len(data) >= 2:
-                self.handler.close_code = struct.unpack('>H', data[:2])[0]
-            if len(data) > 2:
-                self.handler.close_reason = to_unicode(data[2:])
-            # Echo the received close code, if any (RFC 6455 section 5.5.1).
-            self.close(self.handler.close_code)
-        elif opcode == 0x9:
-            # Ping
-            self._write_frame(True, 0xA, data)
-            self._run_callback(self.handler.on_ping, data)
-        elif opcode == 0xA:
-            # Pong
-            self.last_pong = IOLoop.current().time()
-            return self._run_callback(self.handler.on_pong, data)
-        else:
-            self._abort()
-
-    def close(self, code=None, reason=None):
-        """Closes the WebSocket connection."""
-        if not self.server_terminated:
-            if not self.stream.closed():
-                if code is None and reason is not None:
-                    code = 1000  # "normal closure" status code
-                if code is None:
-                    close_data = b''
-                else:
-                    close_data = struct.pack('>H', code)
-                if reason is not None:
-                    close_data += utf8(reason)
-                self._write_frame(True, 0x8, close_data)
-            self.server_terminated = True
-        if self.client_terminated:
-            if self._waiting is not None:
-                self.stream.io_loop.remove_timeout(self._waiting)
-                self._waiting = None
-            self.stream.close()
-        elif self._waiting is None:
-            # Give the client a few seconds to complete a clean shutdown,
-            # otherwise just close the connection.
-            self._waiting = self.stream.io_loop.add_timeout(
-                self.stream.io_loop.time() + 5, self._abort)
-
-    @property
-    def ping_interval(self):
-        interval = self.handler.ping_interval
-        if interval is not None:
-            return interval
-        return 0
-
-    @property
-    def ping_timeout(self):
-        timeout = self.handler.ping_timeout
-        if timeout is not None:
-            return timeout
-        return max(3 * self.ping_interval, 30)
-
-    def start_pinging(self):
-        """Start sending periodic pings to keep the connection alive"""
-        if self.ping_interval > 0:
-            self.last_ping = self.last_pong = IOLoop.current().time()
-            self.ping_callback = PeriodicCallback(
-                self.periodic_ping, self.ping_interval * 1000)
-            self.ping_callback.start()
-
-    def periodic_ping(self):
-        """Send a ping to keep the websocket alive
-
-        Called periodically if the websocket_ping_interval is set and non-zero.
-        """
-        if self.stream.closed() and self.ping_callback is not None:
-            self.ping_callback.stop()
-            return
-
-        # Check for timeout on pong. Make sure that we really have
-        # sent a recent ping in case the machine with both server and
-        # client has been suspended since the last ping.
-        now = IOLoop.current().time()
-        since_last_pong = now - self.last_pong
-        since_last_ping = now - self.last_ping
-        if (since_last_ping < 2 * self.ping_interval and
-                since_last_pong > self.ping_timeout):
-            self.close()
-            return
-
-        self.write_ping(b'')
-        self.last_ping = now
-
-
-class WebSocketClientConnection(simple_httpclient._HTTPConnection):
-    """WebSocket client connection.
-
-    This class should not be instantiated directly; use the
-    `websocket_connect` function instead.
-    """
-    def __init__(self, io_loop, request, on_message_callback=None,
-                 compression_options=None, ping_interval=None, ping_timeout=None,
-                 max_message_size=None):
-        self.compression_options = compression_options
-        self.connect_future = TracebackFuture()
-        self.protocol = None
-        self.read_future = None
-        self.read_queue = collections.deque()
-        self.key = base64.b64encode(os.urandom(16))
-        self._on_message_callback = on_message_callback
-        self.close_code = self.close_reason = None
-        self.ping_interval = ping_interval
-        self.ping_timeout = ping_timeout
-        self.max_message_size = max_message_size
-
-        scheme, sep, rest = request.url.partition(':')
-        scheme = {'ws': 'http', 'wss': 'https'}[scheme]
-        request.url = scheme + sep + rest
-        request.headers.update({
-            'Upgrade': 'websocket',
-            'Connection': 'Upgrade',
-            'Sec-WebSocket-Key': self.key,
-            'Sec-WebSocket-Version': '13',
-        })
-        if self.compression_options is not None:
-            # Always offer to let the server set our max_wbits (and even though
-            # we don't offer it, we will accept a client_no_context_takeover
-            # from the server).
-            # TODO: set server parameters for deflate extension
-            # if requested in self.compression_options.
-            request.headers['Sec-WebSocket-Extensions'] = (
-                'permessage-deflate; client_max_window_bits')
-
-        self.tcp_client = TCPClient(io_loop=io_loop)
-        super(WebSocketClientConnection, self).__init__(
-            io_loop, None, request, lambda: None, self._on_http_response,
-            104857600, self.tcp_client, 65536, 104857600)
-
-    def close(self, code=None, reason=None):
-        """Closes the websocket connection.
-
-        ``code`` and ``reason`` are documented under
-        `WebSocketHandler.close`.
-
-        .. versionadded:: 3.2
-
-        .. versionchanged:: 4.0
-
-           Added the ``code`` and ``reason`` arguments.
-        """
-        if self.protocol is not None:
-            self.protocol.close(code, reason)
-            self.protocol = None
-
-    def on_connection_close(self):
-        if not self.connect_future.done():
-            self.connect_future.set_exception(StreamClosedError())
-        self.on_message(None)
-        self.tcp_client.close()
-        super(WebSocketClientConnection, self).on_connection_close()
-
-    def _on_http_response(self, response):
-        if not self.connect_future.done():
-            if response.error:
-                self.connect_future.set_exception(response.error)
-            else:
-                self.connect_future.set_exception(WebSocketError(
-                    "Non-websocket response"))
-
-    def headers_received(self, start_line, headers):
-        if start_line.code != 101:
-            return super(WebSocketClientConnection, self).headers_received(
-                start_line, headers)
-
-        self.headers = headers
-        self.protocol = self.get_websocket_protocol()
-        self.protocol._process_server_headers(self.key, self.headers)
-        self.protocol.start_pinging()
-        self.protocol._receive_frame()
-
-        if self._timeout is not None:
-            self.io_loop.remove_timeout(self._timeout)
-            self._timeout = None
-
-        self.stream = self.connection.detach()
-        self.stream.set_close_callback(self.on_connection_close)
-        # Once we've taken over the connection, clear the final callback
-        # we set on the http request.  This deactivates the error handling
-        # in simple_httpclient that would otherwise interfere with our
-        # ability to see exceptions.
-        self.final_callback = None
-
-        self.connect_future.set_result(self)
-
-    def write_message(self, message, binary=False):
-        """Sends a message to the WebSocket server."""
-        return self.protocol.write_message(message, binary)
-
-    def read_message(self, callback=None):
-        """Reads a message from the WebSocket server.
-
-        If on_message_callback was specified at WebSocket
-        initialization, this function will never return messages
-
-        Returns a future whose result is the message, or None
-        if the connection is closed.  If a callback argument
-        is given it will be called with the future when it is
-        ready.
-        """
-        assert self.read_future is None
-        future = TracebackFuture()
-        if self.read_queue:
-            future.set_result(self.read_queue.popleft())
-        else:
-            self.read_future = future
-        if callback is not None:
-            self.io_loop.add_future(future, callback)
-        return future
-
-    def on_message(self, message):
-        if self._on_message_callback:
-            self._on_message_callback(message)
-        elif self.read_future is not None:
-            self.read_future.set_result(message)
-            self.read_future = None
-        else:
-            self.read_queue.append(message)
-
-    def on_pong(self, data):
-        pass
-
-    def on_ping(self, data):
-        pass
-
-    def get_websocket_protocol(self):
-        return WebSocketProtocol13(self, mask_outgoing=True,
-                                   compression_options=self.compression_options)
-
-
-def websocket_connect(url, io_loop=None, callback=None, connect_timeout=None,
-                      on_message_callback=None, compression_options=None,
-                      ping_interval=None, ping_timeout=None,
-                      max_message_size=None):
-    """Client-side websocket support.
-
-    Takes a url and returns a Future whose result is a
-    `WebSocketClientConnection`.
-
-    ``compression_options`` is interpreted in the same way as the
-    return value of `.WebSocketHandler.get_compression_options`.
-
-    The connection supports two styles of operation. In the coroutine
-    style, the application typically calls
-    `~.WebSocketClientConnection.read_message` in a loop::
-
-        conn = yield websocket_connect(url)
-        while True:
-            msg = yield conn.read_message()
-            if msg is None: break
-            # Do something with msg
-
-    In the callback style, pass an ``on_message_callback`` to
-    ``websocket_connect``. In both styles, a message of ``None``
-    indicates that the connection has been closed.
-
-    .. versionchanged:: 3.2
-       Also accepts ``HTTPRequest`` objects in place of urls.
-
-    .. versionchanged:: 4.1
-       Added ``compression_options`` and ``on_message_callback``.
-       The ``io_loop`` argument is deprecated.
-
-    .. versionchanged:: 4.5
-       Added the ``ping_interval``, ``ping_timeout``, and ``max_message_size``
-       arguments, which have the same meaning as in `WebSocketHandler`.
-    """
-    if io_loop is None:
-        io_loop = IOLoop.current()
-    if isinstance(url, httpclient.HTTPRequest):
-        assert connect_timeout is None
-        request = url
-        # Copy and convert the headers dict/object (see comments in
-        # AsyncHTTPClient.fetch)
-        request.headers = httputil.HTTPHeaders(request.headers)
-    else:
-        request = httpclient.HTTPRequest(url, connect_timeout=connect_timeout)
-    request = httpclient._RequestProxy(
-        request, httpclient.HTTPRequest._DEFAULTS)
-    conn = WebSocketClientConnection(io_loop, request,
-                                     on_message_callback=on_message_callback,
-                                     compression_options=compression_options,
-                                     ping_interval=ping_interval,
-                                     ping_timeout=ping_timeout,
-                                     max_message_size=max_message_size)
-    if callback is not None:
-        io_loop.add_future(conn.connect_future, callback)
-    return conn.connect_future
+"""Implementation of the WebSocket protocol. 
+ 
+`WebSockets <http://dev.w3.org/html5/websockets/>`_ allow for bidirectional 
+communication between the browser and server. 
+ 
+WebSockets are supported in the current versions of all major browsers, 
+although older versions that do not support WebSockets are still in use 
+(refer to http://caniuse.com/websockets for details). 
+ 
+This module implements the final version of the WebSocket protocol as 
+defined in `RFC 6455 <http://tools.ietf.org/html/rfc6455>`_.  Certain 
+browser versions (notably Safari 5.x) implemented an earlier draft of 
+the protocol (known as "draft 76") and are not compatible with this module. 
+ 
+.. versionchanged:: 4.0 
+   Removed support for the draft 76 protocol version. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+# Author: Jacob Kristhammar, 2010 
+ 
+import base64 
+import collections 
+import hashlib 
+import os 
+import struct 
+import tornado.escape 
+import tornado.web 
+import zlib 
+ 
+from tornado.concurrent import TracebackFuture 
+from tornado.escape import utf8, native_str, to_unicode 
+from tornado import gen, httpclient, httputil 
+from tornado.ioloop import IOLoop, PeriodicCallback 
+from tornado.iostream import StreamClosedError 
+from tornado.log import gen_log, app_log 
+from tornado import simple_httpclient 
+from tornado.tcpclient import TCPClient 
+from tornado.util import _websocket_mask, PY3 
+ 
+if PY3: 
+    from urllib.parse import urlparse  # py2 
+    xrange = range 
+else: 
+    from urlparse import urlparse  # py3 
+ 
+ 
+class WebSocketError(Exception): 
+    pass 
+ 
+ 
+class WebSocketClosedError(WebSocketError): 
+    """Raised by operations on a closed connection. 
+ 
+    .. versionadded:: 3.2 
+    """ 
+    pass 
+ 
+ 
+class WebSocketHandler(tornado.web.RequestHandler): 
+    """Subclass this class to create a basic WebSocket handler. 
+ 
+    Override `on_message` to handle incoming messages, and use 
+    `write_message` to send messages to the client. You can also 
+    override `open` and `on_close` to handle opened and closed 
+    connections. 
+ 
+    Custom upgrade response headers can be sent by overriding 
+    `~tornado.web.RequestHandler.set_default_headers` or 
+    `~tornado.web.RequestHandler.prepare`. 
+ 
+    See http://dev.w3.org/html5/websockets/ for details on the 
+    JavaScript interface.  The protocol is specified at 
+    http://tools.ietf.org/html/rfc6455. 
+ 
+    Here is an example WebSocket handler that echos back all received messages 
+    back to the client: 
+ 
+    .. testcode:: 
+ 
+      class EchoWebSocket(tornado.websocket.WebSocketHandler): 
+          def open(self): 
+              print("WebSocket opened") 
+ 
+          def on_message(self, message): 
+              self.write_message(u"You said: " + message) 
+ 
+          def on_close(self): 
+              print("WebSocket closed") 
+ 
+    .. testoutput:: 
+       :hide: 
+ 
+    WebSockets are not standard HTTP connections. The "handshake" is 
+    HTTP, but after the handshake, the protocol is 
+    message-based. Consequently, most of the Tornado HTTP facilities 
+    are not available in handlers of this type. The only communication 
+    methods available to you are `write_message()`, `ping()`, and 
+    `close()`. Likewise, your request handler class should implement 
+    `open()` method rather than ``get()`` or ``post()``. 
+ 
+    If you map the handler above to ``/websocket`` in your application, you can 
+    invoke it in JavaScript with:: 
+ 
+      var ws = new WebSocket("ws://localhost:8888/websocket"); 
+      ws.onopen = function() { 
+         ws.send("Hello, world"); 
+      }; 
+      ws.onmessage = function (evt) { 
+         alert(evt.data); 
+      }; 
+ 
+    This script pops up an alert box that says "You said: Hello, world". 
+ 
+    Web browsers allow any site to open a websocket connection to any other, 
+    instead of using the same-origin policy that governs other network 
+    access from javascript.  This can be surprising and is a potential 
+    security hole, so since Tornado 4.0 `WebSocketHandler` requires 
+    applications that wish to receive cross-origin websockets to opt in 
+    by overriding the `~WebSocketHandler.check_origin` method (see that 
+    method's docs for details).  Failure to do so is the most likely 
+    cause of 403 errors when making a websocket connection. 
+ 
+    When using a secure websocket connection (``wss://``) with a self-signed 
+    certificate, the connection from a browser may fail because it wants 
+    to show the "accept this certificate" dialog but has nowhere to show it. 
+    You must first visit a regular HTML page using the same certificate 
+    to accept it before the websocket connection will succeed. 
+ 
+    If the application setting ``websocket_ping_interval`` has a non-zero 
+    value, a ping will be sent periodically, and the connection will be 
+    closed if a response is not received before the ``websocket_ping_timeout``. 
+ 
+    Messages larger than the ``websocket_max_message_size`` application setting 
+    (default 10MiB) will not be accepted. 
+ 
+    .. versionchanged:: 4.5 
+       Added ``websocket_ping_interval``, ``websocket_ping_timeout``, and 
+       ``websocket_max_message_size``. 
+    """ 
+    def __init__(self, application, request, **kwargs): 
+        super(WebSocketHandler, self).__init__(application, request, **kwargs) 
+        self.ws_connection = None 
+        self.close_code = None 
+        self.close_reason = None 
+        self.stream = None 
+        self._on_close_called = False 
+ 
+    @tornado.web.asynchronous 
+    def get(self, *args, **kwargs): 
+        self.open_args = args 
+        self.open_kwargs = kwargs 
+ 
+        # Upgrade header should be present and should be equal to WebSocket 
+        if self.request.headers.get("Upgrade", "").lower() != 'websocket': 
+            self.set_status(400) 
+            log_msg = "Can \"Upgrade\" only to \"WebSocket\"." 
+            self.finish(log_msg) 
+            gen_log.debug(log_msg) 
+            return 
+ 
+        # Connection header should be upgrade. 
+        # Some proxy servers/load balancers 
+        # might mess with it. 
+        headers = self.request.headers 
+        connection = map(lambda s: s.strip().lower(), 
+                         headers.get("Connection", "").split(",")) 
+        if 'upgrade' not in connection: 
+            self.set_status(400) 
+            log_msg = "\"Connection\" must be \"Upgrade\"." 
+            self.finish(log_msg) 
+            gen_log.debug(log_msg) 
+            return 
+ 
+        # Handle WebSocket Origin naming convention differences 
+        # The difference between version 8 and 13 is that in 8 the 
+        # client sends a "Sec-Websocket-Origin" header and in 13 it's 
+        # simply "Origin". 
+        if "Origin" in self.request.headers: 
+            origin = self.request.headers.get("Origin") 
+        else: 
+            origin = self.request.headers.get("Sec-Websocket-Origin", None) 
+ 
+        # If there was an origin header, check to make sure it matches 
+        # according to check_origin. When the origin is None, we assume it 
+        # did not come from a browser and that it can be passed on. 
+        if origin is not None and not self.check_origin(origin): 
+            self.set_status(403) 
+            log_msg = "Cross origin websockets not allowed" 
+            self.finish(log_msg) 
+            gen_log.debug(log_msg) 
+            return 
+ 
+        self.ws_connection = self.get_websocket_protocol() 
+        if self.ws_connection: 
+            self.ws_connection.accept_connection() 
+        else: 
+            self.set_status(426, "Upgrade Required") 
+            self.set_header("Sec-WebSocket-Version", "7, 8, 13") 
+            self.finish() 
+ 
+    stream = None 
+ 
+    @property 
+    def ping_interval(self): 
+        """The interval for websocket keep-alive pings. 
+ 
+        Set websocket_ping_interval = 0 to disable pings. 
+        """ 
+        return self.settings.get('websocket_ping_interval', None) 
+ 
+    @property 
+    def ping_timeout(self): 
+        """If no ping is received in this many seconds, 
+        close the websocket connection (VPNs, etc. can fail to cleanly close ws connections). 
+        Default is max of 3 pings or 30 seconds. 
+        """ 
+        return self.settings.get('websocket_ping_timeout', None) 
+ 
+    @property 
+    def max_message_size(self): 
+        """Maximum allowed message size. 
+ 
+        If the remote peer sends a message larger than this, the connection 
+        will be closed. 
+ 
+        Default is 10MiB. 
+        """ 
+        return self.settings.get('websocket_max_message_size', None) 
+ 
+    def write_message(self, message, binary=False): 
+        """Sends the given message to the client of this Web Socket. 
+ 
+        The message may be either a string or a dict (which will be 
+        encoded as json).  If the ``binary`` argument is false, the 
+        message will be sent as utf8; in binary mode any byte string 
+        is allowed. 
+ 
+        If the connection is already closed, raises `WebSocketClosedError`. 
+ 
+        .. versionchanged:: 3.2 
+           `WebSocketClosedError` was added (previously a closed connection 
+           would raise an `AttributeError`) 
+ 
+        .. versionchanged:: 4.3 
+           Returns a `.Future` which can be used for flow control. 
+        """ 
+        if self.ws_connection is None: 
+            raise WebSocketClosedError() 
+        if isinstance(message, dict): 
+            message = tornado.escape.json_encode(message) 
+        return self.ws_connection.write_message(message, binary=binary) 
+ 
+    def select_subprotocol(self, subprotocols): 
+        """Invoked when a new WebSocket requests specific subprotocols. 
+ 
+        ``subprotocols`` is a list of strings identifying the 
+        subprotocols proposed by the client.  This method may be 
+        overridden to return one of those strings to select it, or 
+        ``None`` to not select a subprotocol.  Failure to select a 
+        subprotocol does not automatically abort the connection, 
+        although clients may close the connection if none of their 
+        proposed subprotocols was selected. 
+        """ 
+        return None 
+ 
+    def get_compression_options(self): 
+        """Override to return compression options for the connection. 
+ 
+        If this method returns None (the default), compression will 
+        be disabled.  If it returns a dict (even an empty one), it 
+        will be enabled.  The contents of the dict may be used to 
+        control the following compression options: 
+ 
+        ``compression_level`` specifies the compression level. 
+ 
+        ``mem_level`` specifies the amount of memory used for the internal compression state. 
+ 
+         These parameters are documented in details here: 
+         https://docs.python.org/3.6/library/zlib.html#zlib.compressobj 
+ 
+        .. versionadded:: 4.1 
+ 
+        .. versionchanged:: 4.5 
+ 
+           Added ``compression_level`` and ``mem_level``. 
+        """ 
+        # TODO: Add wbits option. 
+        return None 
+ 
+    def open(self, *args, **kwargs): 
+        """Invoked when a new WebSocket is opened. 
+ 
+        The arguments to `open` are extracted from the `tornado.web.URLSpec` 
+        regular expression, just like the arguments to 
+        `tornado.web.RequestHandler.get`. 
+        """ 
+        pass 
+ 
+    def on_message(self, message): 
+        """Handle incoming messages on the WebSocket 
+ 
+        This method must be overridden. 
+ 
+        .. versionchanged:: 4.5 
+ 
+           ``on_message`` can be a coroutine. 
+        """ 
+        raise NotImplementedError 
+ 
+    def ping(self, data): 
+        """Send ping frame to the remote end.""" 
+        if self.ws_connection is None: 
+            raise WebSocketClosedError() 
+        self.ws_connection.write_ping(data) 
+ 
+    def on_pong(self, data): 
+        """Invoked when the response to a ping frame is received.""" 
+        pass 
+ 
+    def on_ping(self, data): 
+        """Invoked when the a ping frame is received.""" 
+        pass 
+ 
+    def on_close(self): 
+        """Invoked when the WebSocket is closed. 
+ 
+        If the connection was closed cleanly and a status code or reason 
+        phrase was supplied, these values will be available as the attributes 
+        ``self.close_code`` and ``self.close_reason``. 
+ 
+        .. versionchanged:: 4.0 
+ 
+           Added ``close_code`` and ``close_reason`` attributes. 
+        """ 
+        pass 
+ 
+    def close(self, code=None, reason=None): 
+        """Closes this Web Socket. 
+ 
+        Once the close handshake is successful the socket will be closed. 
+ 
+        ``code`` may be a numeric status code, taken from the values 
+        defined in `RFC 6455 section 7.4.1 
+        <https://tools.ietf.org/html/rfc6455#section-7.4.1>`_. 
+        ``reason`` may be a textual message about why the connection is 
+        closing.  These values are made available to the client, but are 
+        not otherwise interpreted by the websocket protocol. 
+ 
+        .. versionchanged:: 4.0 
+ 
+           Added the ``code`` and ``reason`` arguments. 
+        """ 
+        if self.ws_connection: 
+            self.ws_connection.close(code, reason) 
+            self.ws_connection = None 
+ 
+    def check_origin(self, origin): 
+        """Override to enable support for allowing alternate origins. 
+ 
+        The ``origin`` argument is the value of the ``Origin`` HTTP 
+        header, the url responsible for initiating this request.  This 
+        method is not called for clients that do not send this header; 
+        such requests are always allowed (because all browsers that 
+        implement WebSockets support this header, and non-browser 
+        clients do not have the same cross-site security concerns). 
+ 
+        Should return True to accept the request or False to reject it. 
+        By default, rejects all requests with an origin on a host other 
+        than this one. 
+ 
+        This is a security protection against cross site scripting attacks on 
+        browsers, since WebSockets are allowed to bypass the usual same-origin 
+        policies and don't use CORS headers. 
+ 
+        .. warning:: 
+ 
+           This is an important security measure; don't disable it 
+           without understanding the security implications. In 
+           particular, if your authentication is cookie-based, you 
+           must either restrict the origins allowed by 
+           ``check_origin()`` or implement your own XSRF-like 
+           protection for websocket connections. See `these 
+           <https://www.christian-schneider.net/CrossSiteWebSocketHijacking.html>`_ 
+           `articles 
+           <https://devcenter.heroku.com/articles/websocket-security>`_ 
+           for more. 
+ 
+        To accept all cross-origin traffic (which was the default prior to 
+        Tornado 4.0), simply override this method to always return true:: 
+ 
+            def check_origin(self, origin): 
+                return True 
+ 
+        To allow connections from any subdomain of your site, you might 
+        do something like:: 
+ 
+            def check_origin(self, origin): 
+                parsed_origin = urllib.parse.urlparse(origin) 
+                return parsed_origin.netloc.endswith(".mydomain.com") 
+ 
+        .. versionadded:: 4.0 
+ 
+        """ 
+        parsed_origin = urlparse(origin) 
+        origin = parsed_origin.netloc 
+        origin = origin.lower() 
+ 
+        host = self.request.headers.get("Host") 
+ 
+        # Check to see that origin matches host directly, including ports 
+        return origin == host 
+ 
+    def set_nodelay(self, value): 
+        """Set the no-delay flag for this stream. 
+ 
+        By default, small messages may be delayed and/or combined to minimize 
+        the number of packets sent.  This can sometimes cause 200-500ms delays 
+        due to the interaction between Nagle's algorithm and TCP delayed 
+        ACKs.  To reduce this delay (at the expense of possibly increasing 
+        bandwidth usage), call ``self.set_nodelay(True)`` once the websocket 
+        connection is established. 
+ 
+        See `.BaseIOStream.set_nodelay` for additional details. 
+ 
+        .. versionadded:: 3.1 
+        """ 
+        self.stream.set_nodelay(value) 
+ 
+    def on_connection_close(self): 
+        if self.ws_connection: 
+            self.ws_connection.on_connection_close() 
+            self.ws_connection = None 
+        if not self._on_close_called: 
+            self._on_close_called = True 
+            self.on_close() 
+            self._break_cycles() 
+ 
+    def _break_cycles(self): 
+        # WebSocketHandlers call finish() early, but we don't want to 
+        # break up reference cycles (which makes it impossible to call 
+        # self.render_string) until after we've really closed the 
+        # connection (if it was established in the first place, 
+        # indicated by status code 101). 
+        if self.get_status() != 101 or self._on_close_called: 
+            super(WebSocketHandler, self)._break_cycles() 
+ 
+    def send_error(self, *args, **kwargs): 
+        if self.stream is None: 
+            super(WebSocketHandler, self).send_error(*args, **kwargs) 
+        else: 
+            # If we get an uncaught exception during the handshake, 
+            # we have no choice but to abruptly close the connection. 
+            # TODO: for uncaught exceptions after the handshake, 
+            # we can close the connection more gracefully. 
+            self.stream.close() 
+ 
+    def get_websocket_protocol(self): 
+        websocket_version = self.request.headers.get("Sec-WebSocket-Version") 
+        if websocket_version in ("7", "8", "13"): 
+            return WebSocketProtocol13( 
+                self, compression_options=self.get_compression_options()) 
+ 
+    def _attach_stream(self): 
+        self.stream = self.request.connection.detach() 
+        self.stream.set_close_callback(self.on_connection_close) 
+        # disable non-WS methods 
+        for method in ["write", "redirect", "set_header", "set_cookie", 
+                       "set_status", "flush", "finish"]: 
+            setattr(self, method, _raise_not_supported_for_websockets) 
+ 
+ 
+def _raise_not_supported_for_websockets(*args, **kwargs): 
+    raise RuntimeError("Method not supported for Web Sockets") 
+ 
+ 
+class WebSocketProtocol(object): 
+    """Base class for WebSocket protocol versions. 
+    """ 
+    def __init__(self, handler): 
+        self.handler = handler 
+        self.request = handler.request 
+        self.stream = handler.stream 
+        self.client_terminated = False 
+        self.server_terminated = False 
+ 
+    def _run_callback(self, callback, *args, **kwargs): 
+        """Runs the given callback with exception handling. 
+ 
+        If the callback is a coroutine, returns its Future. On error, aborts the 
+        websocket connection and returns None. 
+        """ 
+        try: 
+            result = callback(*args, **kwargs) 
+        except Exception: 
+            app_log.error("Uncaught exception in %s", 
+                          getattr(self.request, 'path', None), exc_info=True) 
+            self._abort() 
+        else: 
+            if result is not None: 
+                result = gen.convert_yielded(result) 
+                self.stream.io_loop.add_future(result, lambda f: f.result()) 
+            return result 
+ 
+    def on_connection_close(self): 
+        self._abort() 
+ 
+    def _abort(self): 
+        """Instantly aborts the WebSocket connection by closing the socket""" 
+        self.client_terminated = True 
+        self.server_terminated = True 
+        self.stream.close()  # forcibly tear down the connection 
+        self.close()  # let the subclass cleanup 
+ 
+ 
+class _PerMessageDeflateCompressor(object): 
+    def __init__(self, persistent, max_wbits, compression_options=None): 
+        if max_wbits is None: 
+            max_wbits = zlib.MAX_WBITS 
+        # There is no symbolic constant for the minimum wbits value. 
+        if not (8 <= max_wbits <= zlib.MAX_WBITS): 
+            raise ValueError("Invalid max_wbits value %r; allowed range 8-%d", 
+                             max_wbits, zlib.MAX_WBITS) 
+        self._max_wbits = max_wbits 
+ 
+        if compression_options is None or 'compression_level' not in compression_options: 
+            self._compression_level = tornado.web.GZipContentEncoding.GZIP_LEVEL 
+        else: 
+            self._compression_level = compression_options['compression_level'] 
+ 
+        if compression_options is None or 'mem_level' not in compression_options: 
+            self._mem_level = 8 
+        else: 
+            self._mem_level = compression_options['mem_level'] 
+ 
+        if persistent: 
+            self._compressor = self._create_compressor() 
+        else: 
+            self._compressor = None 
+ 
+    def _create_compressor(self): 
+        return zlib.compressobj(self._compression_level, zlib.DEFLATED, -self._max_wbits, self._mem_level) 
+ 
+    def compress(self, data): 
+        compressor = self._compressor or self._create_compressor() 
+        data = (compressor.compress(data) + 
+                compressor.flush(zlib.Z_SYNC_FLUSH)) 
+        assert data.endswith(b'\x00\x00\xff\xff') 
+        return data[:-4] 
+ 
+ 
+class _PerMessageDeflateDecompressor(object): 
+    def __init__(self, persistent, max_wbits, compression_options=None): 
+        if max_wbits is None: 
+            max_wbits = zlib.MAX_WBITS 
+        if not (8 <= max_wbits <= zlib.MAX_WBITS): 
+            raise ValueError("Invalid max_wbits value %r; allowed range 8-%d", 
+                             max_wbits, zlib.MAX_WBITS) 
+        self._max_wbits = max_wbits 
+        if persistent: 
+            self._decompressor = self._create_decompressor() 
+        else: 
+            self._decompressor = None 
+ 
+    def _create_decompressor(self): 
+        return zlib.decompressobj(-self._max_wbits) 
+ 
+    def decompress(self, data): 
+        decompressor = self._decompressor or self._create_decompressor() 
+        return decompressor.decompress(data + b'\x00\x00\xff\xff') 
+ 
+ 
+class WebSocketProtocol13(WebSocketProtocol): 
+    """Implementation of the WebSocket protocol from RFC 6455. 
+ 
+    This class supports versions 7 and 8 of the protocol in addition to the 
+    final version 13. 
+    """ 
+    # Bit masks for the first byte of a frame. 
+    FIN = 0x80 
+    RSV1 = 0x40 
+    RSV2 = 0x20 
+    RSV3 = 0x10 
+    RSV_MASK = RSV1 | RSV2 | RSV3 
+    OPCODE_MASK = 0x0f 
+ 
+    def __init__(self, handler, mask_outgoing=False, 
+                 compression_options=None): 
+        WebSocketProtocol.__init__(self, handler) 
+        self.mask_outgoing = mask_outgoing 
+        self._final_frame = False 
+        self._frame_opcode = None 
+        self._masked_frame = None 
+        self._frame_mask = None 
+        self._frame_length = None 
+        self._fragmented_message_buffer = None 
+        self._fragmented_message_opcode = None 
+        self._waiting = None 
+        self._compression_options = compression_options 
+        self._decompressor = None 
+        self._compressor = None 
+        self._frame_compressed = None 
+        # The total uncompressed size of all messages received or sent. 
+        # Unicode messages are encoded to utf8. 
+        # Only for testing; subject to change. 
+        self._message_bytes_in = 0 
+        self._message_bytes_out = 0 
+        # The total size of all packets received or sent.  Includes 
+        # the effect of compression, frame overhead, and control frames. 
+        self._wire_bytes_in = 0 
+        self._wire_bytes_out = 0 
+        self.ping_callback = None 
+        self.last_ping = 0 
+        self.last_pong = 0 
+ 
+    def accept_connection(self): 
+        try: 
+            self._handle_websocket_headers() 
+        except ValueError: 
+            self.handler.set_status(400) 
+            log_msg = "Missing/Invalid WebSocket headers" 
+            self.handler.finish(log_msg) 
+            gen_log.debug(log_msg) 
+            return 
+ 
+        try: 
+            self._accept_connection() 
+        except ValueError: 
+            gen_log.debug("Malformed WebSocket request received", 
+                          exc_info=True) 
+            self._abort() 
+            return 
+ 
+    def _handle_websocket_headers(self): 
+        """Verifies all invariant- and required headers 
+ 
+        If a header is missing or have an incorrect value ValueError will be 
+        raised 
+        """ 
+        fields = ("Host", "Sec-Websocket-Key", "Sec-Websocket-Version") 
+        if not all(map(lambda f: self.request.headers.get(f), fields)): 
+            raise ValueError("Missing/Invalid WebSocket headers") 
+ 
+    @staticmethod 
+    def compute_accept_value(key): 
+        """Computes the value for the Sec-WebSocket-Accept header, 
+        given the value for Sec-WebSocket-Key. 
+        """ 
+        sha1 = hashlib.sha1() 
+        sha1.update(utf8(key)) 
+        sha1.update(b"258EAFA5-E914-47DA-95CA-C5AB0DC85B11")  # Magic value 
+        return native_str(base64.b64encode(sha1.digest())) 
+ 
+    def _challenge_response(self): 
+        return WebSocketProtocol13.compute_accept_value( 
+            self.request.headers.get("Sec-Websocket-Key")) 
+ 
+    def _accept_connection(self): 
+        subprotocols = self.request.headers.get("Sec-WebSocket-Protocol", '') 
+        subprotocols = [s.strip() for s in subprotocols.split(',')] 
+        if subprotocols: 
+            selected = self.handler.select_subprotocol(subprotocols) 
+            if selected: 
+                assert selected in subprotocols 
+                self.handler.set_header("Sec-WebSocket-Protocol", selected) 
+ 
+        extensions = self._parse_extensions_header(self.request.headers) 
+        for ext in extensions: 
+            if (ext[0] == 'permessage-deflate' and 
+                    self._compression_options is not None): 
+                # TODO: negotiate parameters if compression_options 
+                # specifies limits. 
+                self._create_compressors('server', ext[1], self._compression_options) 
+                if ('client_max_window_bits' in ext[1] and 
+                        ext[1]['client_max_window_bits'] is None): 
+                    # Don't echo an offered client_max_window_bits 
+                    # parameter with no value. 
+                    del ext[1]['client_max_window_bits'] 
+                self.handler.set_header("Sec-WebSocket-Extensions", 
+                                        httputil._encode_header( 
+                                            'permessage-deflate', ext[1])) 
+                break 
+ 
+        self.handler.clear_header("Content-Type") 
+        self.handler.set_status(101) 
+        self.handler.set_header("Upgrade", "websocket") 
+        self.handler.set_header("Connection", "Upgrade") 
+        self.handler.set_header("Sec-WebSocket-Accept", self._challenge_response()) 
+        self.handler.finish() 
+ 
+        self.handler._attach_stream() 
+        self.stream = self.handler.stream 
+ 
+        self.start_pinging() 
+        self._run_callback(self.handler.open, *self.handler.open_args, 
+                           **self.handler.open_kwargs) 
+        self._receive_frame() 
+ 
+    def _parse_extensions_header(self, headers): 
+        extensions = headers.get("Sec-WebSocket-Extensions", '') 
+        if extensions: 
+            return [httputil._parse_header(e.strip()) 
+                    for e in extensions.split(',')] 
+        return [] 
+ 
+    def _process_server_headers(self, key, headers): 
+        """Process the headers sent by the server to this client connection. 
+ 
+        'key' is the websocket handshake challenge/response key. 
+        """ 
+        assert headers['Upgrade'].lower() == 'websocket' 
+        assert headers['Connection'].lower() == 'upgrade' 
+        accept = self.compute_accept_value(key) 
+        assert headers['Sec-Websocket-Accept'] == accept 
+ 
+        extensions = self._parse_extensions_header(headers) 
+        for ext in extensions: 
+            if (ext[0] == 'permessage-deflate' and 
+                    self._compression_options is not None): 
+                self._create_compressors('client', ext[1]) 
+            else: 
+                raise ValueError("unsupported extension %r", ext) 
+ 
+    def _get_compressor_options(self, side, agreed_parameters, compression_options=None): 
+        """Converts a websocket agreed_parameters set to keyword arguments 
+        for our compressor objects. 
+        """ 
+        options = dict( 
+            persistent=(side + '_no_context_takeover') not in agreed_parameters) 
+        wbits_header = agreed_parameters.get(side + '_max_window_bits', None) 
+        if wbits_header is None: 
+            options['max_wbits'] = zlib.MAX_WBITS 
+        else: 
+            options['max_wbits'] = int(wbits_header) 
+        options['compression_options'] = compression_options 
+        return options 
+ 
+    def _create_compressors(self, side, agreed_parameters, compression_options=None): 
+        # TODO: handle invalid parameters gracefully 
+        allowed_keys = set(['server_no_context_takeover', 
+                            'client_no_context_takeover', 
+                            'server_max_window_bits', 
+                            'client_max_window_bits']) 
+        for key in agreed_parameters: 
+            if key not in allowed_keys: 
+                raise ValueError("unsupported compression parameter %r" % key) 
+        other_side = 'client' if (side == 'server') else 'server' 
+        self._compressor = _PerMessageDeflateCompressor( 
+            **self._get_compressor_options(side, agreed_parameters, compression_options)) 
+        self._decompressor = _PerMessageDeflateDecompressor( 
+            **self._get_compressor_options(other_side, agreed_parameters, compression_options)) 
+ 
+    def _write_frame(self, fin, opcode, data, flags=0): 
+        if fin: 
+            finbit = self.FIN 
+        else: 
+            finbit = 0 
+        frame = struct.pack("B", finbit | opcode | flags) 
+        l = len(data) 
+        if self.mask_outgoing: 
+            mask_bit = 0x80 
+        else: 
+            mask_bit = 0 
+        if l < 126: 
+            frame += struct.pack("B", l | mask_bit) 
+        elif l <= 0xFFFF: 
+            frame += struct.pack("!BH", 126 | mask_bit, l) 
+        else: 
+            frame += struct.pack("!BQ", 127 | mask_bit, l) 
+        if self.mask_outgoing: 
+            mask = os.urandom(4) 
+            data = mask + _websocket_mask(mask, data) 
+        frame += data 
+        self._wire_bytes_out += len(frame) 
+        try: 
+            return self.stream.write(frame) 
+        except StreamClosedError: 
+            self._abort() 
+ 
+    def write_message(self, message, binary=False): 
+        """Sends the given message to the client of this Web Socket.""" 
+        if binary: 
+            opcode = 0x2 
+        else: 
+            opcode = 0x1 
+        message = tornado.escape.utf8(message) 
+        assert isinstance(message, bytes) 
+        self._message_bytes_out += len(message) 
+        flags = 0 
+        if self._compressor: 
+            message = self._compressor.compress(message) 
+            flags |= self.RSV1 
+        return self._write_frame(True, opcode, message, flags=flags) 
+ 
+    def write_ping(self, data): 
+        """Send ping frame.""" 
+        assert isinstance(data, bytes) 
+        self._write_frame(True, 0x9, data) 
+ 
+    def _receive_frame(self): 
+        try: 
+            self.stream.read_bytes(2, self._on_frame_start) 
+        except StreamClosedError: 
+            self._abort() 
+ 
+    def _on_frame_start(self, data): 
+        self._wire_bytes_in += len(data) 
+        header, payloadlen = struct.unpack("BB", data) 
+        self._final_frame = header & self.FIN 
+        reserved_bits = header & self.RSV_MASK 
+        self._frame_opcode = header & self.OPCODE_MASK 
+        self._frame_opcode_is_control = self._frame_opcode & 0x8 
+        if self._decompressor is not None and self._frame_opcode != 0: 
+            self._frame_compressed = bool(reserved_bits & self.RSV1) 
+            reserved_bits &= ~self.RSV1 
+        if reserved_bits: 
+            # client is using as-yet-undefined extensions; abort 
+            self._abort() 
+            return 
+        self._masked_frame = bool(payloadlen & 0x80) 
+        payloadlen = payloadlen & 0x7f 
+        if self._frame_opcode_is_control and payloadlen >= 126: 
+            # control frames must have payload < 126 
+            self._abort() 
+            return 
+        try: 
+            if payloadlen < 126: 
+                self._frame_length = payloadlen 
+                if self._masked_frame: 
+                    self.stream.read_bytes(4, self._on_masking_key) 
+                else: 
+                    self._read_frame_data(False) 
+            elif payloadlen == 126: 
+                self.stream.read_bytes(2, self._on_frame_length_16) 
+            elif payloadlen == 127: 
+                self.stream.read_bytes(8, self._on_frame_length_64) 
+        except StreamClosedError: 
+            self._abort() 
+ 
+    def _read_frame_data(self, masked): 
+        new_len = self._frame_length 
+        if self._fragmented_message_buffer is not None: 
+            new_len += len(self._fragmented_message_buffer) 
+        if new_len > (self.handler.max_message_size or 10 * 1024 * 1024): 
+            self.close(1009, "message too big") 
+            return 
+        self.stream.read_bytes( 
+            self._frame_length, 
+            self._on_masked_frame_data if masked else self._on_frame_data) 
+ 
+    def _on_frame_length_16(self, data): 
+        self._wire_bytes_in += len(data) 
+        self._frame_length = struct.unpack("!H", data)[0] 
+        try: 
+            if self._masked_frame: 
+                self.stream.read_bytes(4, self._on_masking_key) 
+            else: 
+                self._read_frame_data(False) 
+        except StreamClosedError: 
+            self._abort() 
+ 
+    def _on_frame_length_64(self, data): 
+        self._wire_bytes_in += len(data) 
+        self._frame_length = struct.unpack("!Q", data)[0] 
+        try: 
+            if self._masked_frame: 
+                self.stream.read_bytes(4, self._on_masking_key) 
+            else: 
+                self._read_frame_data(False) 
+        except StreamClosedError: 
+            self._abort() 
+ 
+    def _on_masking_key(self, data): 
+        self._wire_bytes_in += len(data) 
+        self._frame_mask = data 
+        try: 
+            self._read_frame_data(True) 
+        except StreamClosedError: 
+            self._abort() 
+ 
+    def _on_masked_frame_data(self, data): 
+        # Don't touch _wire_bytes_in; we'll do it in _on_frame_data. 
+        self._on_frame_data(_websocket_mask(self._frame_mask, data)) 
+ 
+    def _on_frame_data(self, data): 
+        handled_future = None 
+ 
+        self._wire_bytes_in += len(data) 
+        if self._frame_opcode_is_control: 
+            # control frames may be interleaved with a series of fragmented 
+            # data frames, so control frames must not interact with 
+            # self._fragmented_* 
+            if not self._final_frame: 
+                # control frames must not be fragmented 
+                self._abort() 
+                return 
+            opcode = self._frame_opcode 
+        elif self._frame_opcode == 0:  # continuation frame 
+            if self._fragmented_message_buffer is None: 
+                # nothing to continue 
+                self._abort() 
+                return 
+            self._fragmented_message_buffer += data 
+            if self._final_frame: 
+                opcode = self._fragmented_message_opcode 
+                data = self._fragmented_message_buffer 
+                self._fragmented_message_buffer = None 
+        else:  # start of new data message 
+            if self._fragmented_message_buffer is not None: 
+                # can't start new message until the old one is finished 
+                self._abort() 
+                return 
+            if self._final_frame: 
+                opcode = self._frame_opcode 
+            else: 
+                self._fragmented_message_opcode = self._frame_opcode 
+                self._fragmented_message_buffer = data 
+ 
+        if self._final_frame: 
+            handled_future = self._handle_message(opcode, data) 
+ 
+        if not self.client_terminated: 
+            if handled_future: 
+                # on_message is a coroutine, process more frames once it's done. 
+                handled_future.add_done_callback( 
+                    lambda future: self._receive_frame()) 
+            else: 
+                self._receive_frame() 
+ 
+    def _handle_message(self, opcode, data): 
+        """Execute on_message, returning its Future if it is a coroutine.""" 
+        if self.client_terminated: 
+            return 
+ 
+        if self._frame_compressed: 
+            data = self._decompressor.decompress(data) 
+ 
+        if opcode == 0x1: 
+            # UTF-8 data 
+            self._message_bytes_in += len(data) 
+            try: 
+                decoded = data.decode("utf-8") 
+            except UnicodeDecodeError: 
+                self._abort() 
+                return 
+            return self._run_callback(self.handler.on_message, decoded) 
+        elif opcode == 0x2: 
+            # Binary data 
+            self._message_bytes_in += len(data) 
+            return self._run_callback(self.handler.on_message, data) 
+        elif opcode == 0x8: 
+            # Close 
+            self.client_terminated = True 
+            if len(data) >= 2: 
+                self.handler.close_code = struct.unpack('>H', data[:2])[0] 
+            if len(data) > 2: 
+                self.handler.close_reason = to_unicode(data[2:]) 
+            # Echo the received close code, if any (RFC 6455 section 5.5.1). 
+            self.close(self.handler.close_code) 
+        elif opcode == 0x9: 
+            # Ping 
+            self._write_frame(True, 0xA, data) 
+            self._run_callback(self.handler.on_ping, data) 
+        elif opcode == 0xA: 
+            # Pong 
+            self.last_pong = IOLoop.current().time() 
+            return self._run_callback(self.handler.on_pong, data) 
+        else: 
+            self._abort() 
+ 
+    def close(self, code=None, reason=None): 
+        """Closes the WebSocket connection.""" 
+        if not self.server_terminated: 
+            if not self.stream.closed(): 
+                if code is None and reason is not None: 
+                    code = 1000  # "normal closure" status code 
+                if code is None: 
+                    close_data = b'' 
+                else: 
+                    close_data = struct.pack('>H', code) 
+                if reason is not None: 
+                    close_data += utf8(reason) 
+                self._write_frame(True, 0x8, close_data) 
+            self.server_terminated = True 
+        if self.client_terminated: 
+            if self._waiting is not None: 
+                self.stream.io_loop.remove_timeout(self._waiting) 
+                self._waiting = None 
+            self.stream.close() 
+        elif self._waiting is None: 
+            # Give the client a few seconds to complete a clean shutdown, 
+            # otherwise just close the connection. 
+            self._waiting = self.stream.io_loop.add_timeout( 
+                self.stream.io_loop.time() + 5, self._abort) 
+ 
+    @property 
+    def ping_interval(self): 
+        interval = self.handler.ping_interval 
+        if interval is not None: 
+            return interval 
+        return 0 
+ 
+    @property 
+    def ping_timeout(self): 
+        timeout = self.handler.ping_timeout 
+        if timeout is not None: 
+            return timeout 
+        return max(3 * self.ping_interval, 30) 
+ 
+    def start_pinging(self): 
+        """Start sending periodic pings to keep the connection alive""" 
+        if self.ping_interval > 0: 
+            self.last_ping = self.last_pong = IOLoop.current().time() 
+            self.ping_callback = PeriodicCallback( 
+                self.periodic_ping, self.ping_interval * 1000) 
+            self.ping_callback.start() 
+ 
+    def periodic_ping(self): 
+        """Send a ping to keep the websocket alive 
+ 
+        Called periodically if the websocket_ping_interval is set and non-zero. 
+        """ 
+        if self.stream.closed() and self.ping_callback is not None: 
+            self.ping_callback.stop() 
+            return 
+ 
+        # Check for timeout on pong. Make sure that we really have 
+        # sent a recent ping in case the machine with both server and 
+        # client has been suspended since the last ping. 
+        now = IOLoop.current().time() 
+        since_last_pong = now - self.last_pong 
+        since_last_ping = now - self.last_ping 
+        if (since_last_ping < 2 * self.ping_interval and 
+                since_last_pong > self.ping_timeout): 
+            self.close() 
+            return 
+ 
+        self.write_ping(b'') 
+        self.last_ping = now 
+ 
+ 
+class WebSocketClientConnection(simple_httpclient._HTTPConnection): 
+    """WebSocket client connection. 
+ 
+    This class should not be instantiated directly; use the 
+    `websocket_connect` function instead. 
+    """ 
+    def __init__(self, io_loop, request, on_message_callback=None, 
+                 compression_options=None, ping_interval=None, ping_timeout=None, 
+                 max_message_size=None): 
+        self.compression_options = compression_options 
+        self.connect_future = TracebackFuture() 
+        self.protocol = None 
+        self.read_future = None 
+        self.read_queue = collections.deque() 
+        self.key = base64.b64encode(os.urandom(16)) 
+        self._on_message_callback = on_message_callback 
+        self.close_code = self.close_reason = None 
+        self.ping_interval = ping_interval 
+        self.ping_timeout = ping_timeout 
+        self.max_message_size = max_message_size 
+ 
+        scheme, sep, rest = request.url.partition(':') 
+        scheme = {'ws': 'http', 'wss': 'https'}[scheme] 
+        request.url = scheme + sep + rest 
+        request.headers.update({ 
+            'Upgrade': 'websocket', 
+            'Connection': 'Upgrade', 
+            'Sec-WebSocket-Key': self.key, 
+            'Sec-WebSocket-Version': '13', 
+        }) 
+        if self.compression_options is not None: 
+            # Always offer to let the server set our max_wbits (and even though 
+            # we don't offer it, we will accept a client_no_context_takeover 
+            # from the server). 
+            # TODO: set server parameters for deflate extension 
+            # if requested in self.compression_options. 
+            request.headers['Sec-WebSocket-Extensions'] = ( 
+                'permessage-deflate; client_max_window_bits') 
+ 
+        self.tcp_client = TCPClient(io_loop=io_loop) 
+        super(WebSocketClientConnection, self).__init__( 
+            io_loop, None, request, lambda: None, self._on_http_response, 
+            104857600, self.tcp_client, 65536, 104857600) 
+ 
+    def close(self, code=None, reason=None): 
+        """Closes the websocket connection. 
+ 
+        ``code`` and ``reason`` are documented under 
+        `WebSocketHandler.close`. 
+ 
+        .. versionadded:: 3.2 
+ 
+        .. versionchanged:: 4.0 
+ 
+           Added the ``code`` and ``reason`` arguments. 
+        """ 
+        if self.protocol is not None: 
+            self.protocol.close(code, reason) 
+            self.protocol = None 
+ 
+    def on_connection_close(self): 
+        if not self.connect_future.done(): 
+            self.connect_future.set_exception(StreamClosedError()) 
+        self.on_message(None) 
+        self.tcp_client.close() 
+        super(WebSocketClientConnection, self).on_connection_close() 
+ 
+    def _on_http_response(self, response): 
+        if not self.connect_future.done(): 
+            if response.error: 
+                self.connect_future.set_exception(response.error) 
+            else: 
+                self.connect_future.set_exception(WebSocketError( 
+                    "Non-websocket response")) 
+ 
+    def headers_received(self, start_line, headers): 
+        if start_line.code != 101: 
+            return super(WebSocketClientConnection, self).headers_received( 
+                start_line, headers) 
+ 
+        self.headers = headers 
+        self.protocol = self.get_websocket_protocol() 
+        self.protocol._process_server_headers(self.key, self.headers) 
+        self.protocol.start_pinging() 
+        self.protocol._receive_frame() 
+ 
+        if self._timeout is not None: 
+            self.io_loop.remove_timeout(self._timeout) 
+            self._timeout = None 
+ 
+        self.stream = self.connection.detach() 
+        self.stream.set_close_callback(self.on_connection_close) 
+        # Once we've taken over the connection, clear the final callback 
+        # we set on the http request.  This deactivates the error handling 
+        # in simple_httpclient that would otherwise interfere with our 
+        # ability to see exceptions. 
+        self.final_callback = None 
+ 
+        self.connect_future.set_result(self) 
+ 
+    def write_message(self, message, binary=False): 
+        """Sends a message to the WebSocket server.""" 
+        return self.protocol.write_message(message, binary) 
+ 
+    def read_message(self, callback=None): 
+        """Reads a message from the WebSocket server. 
+ 
+        If on_message_callback was specified at WebSocket 
+        initialization, this function will never return messages 
+ 
+        Returns a future whose result is the message, or None 
+        if the connection is closed.  If a callback argument 
+        is given it will be called with the future when it is 
+        ready. 
+        """ 
+        assert self.read_future is None 
+        future = TracebackFuture() 
+        if self.read_queue: 
+            future.set_result(self.read_queue.popleft()) 
+        else: 
+            self.read_future = future 
+        if callback is not None: 
+            self.io_loop.add_future(future, callback) 
+        return future 
+ 
+    def on_message(self, message): 
+        if self._on_message_callback: 
+            self._on_message_callback(message) 
+        elif self.read_future is not None: 
+            self.read_future.set_result(message) 
+            self.read_future = None 
+        else: 
+            self.read_queue.append(message) 
+ 
+    def on_pong(self, data): 
+        pass 
+ 
+    def on_ping(self, data): 
+        pass 
+ 
+    def get_websocket_protocol(self): 
+        return WebSocketProtocol13(self, mask_outgoing=True, 
+                                   compression_options=self.compression_options) 
+ 
+ 
+def websocket_connect(url, io_loop=None, callback=None, connect_timeout=None, 
+                      on_message_callback=None, compression_options=None, 
+                      ping_interval=None, ping_timeout=None, 
+                      max_message_size=None): 
+    """Client-side websocket support. 
+ 
+    Takes a url and returns a Future whose result is a 
+    `WebSocketClientConnection`. 
+ 
+    ``compression_options`` is interpreted in the same way as the 
+    return value of `.WebSocketHandler.get_compression_options`. 
+ 
+    The connection supports two styles of operation. In the coroutine 
+    style, the application typically calls 
+    `~.WebSocketClientConnection.read_message` in a loop:: 
+ 
+        conn = yield websocket_connect(url) 
+        while True: 
+            msg = yield conn.read_message() 
+            if msg is None: break 
+            # Do something with msg 
+ 
+    In the callback style, pass an ``on_message_callback`` to 
+    ``websocket_connect``. In both styles, a message of ``None`` 
+    indicates that the connection has been closed. 
+ 
+    .. versionchanged:: 3.2 
+       Also accepts ``HTTPRequest`` objects in place of urls. 
+ 
+    .. versionchanged:: 4.1 
+       Added ``compression_options`` and ``on_message_callback``. 
+       The ``io_loop`` argument is deprecated. 
+ 
+    .. versionchanged:: 4.5 
+       Added the ``ping_interval``, ``ping_timeout``, and ``max_message_size`` 
+       arguments, which have the same meaning as in `WebSocketHandler`. 
+    """ 
+    if io_loop is None: 
+        io_loop = IOLoop.current() 
+    if isinstance(url, httpclient.HTTPRequest): 
+        assert connect_timeout is None 
+        request = url 
+        # Copy and convert the headers dict/object (see comments in 
+        # AsyncHTTPClient.fetch) 
+        request.headers = httputil.HTTPHeaders(request.headers) 
+    else: 
+        request = httpclient.HTTPRequest(url, connect_timeout=connect_timeout) 
+    request = httpclient._RequestProxy( 
+        request, httpclient.HTTPRequest._DEFAULTS) 
+    conn = WebSocketClientConnection(io_loop, request, 
+                                     on_message_callback=on_message_callback, 
+                                     compression_options=compression_options, 
+                                     ping_interval=ping_interval, 
+                                     ping_timeout=ping_timeout, 
+                                     max_message_size=max_message_size) 
+    if callback is not None: 
+        io_loop.add_future(conn.connect_future, callback) 
+    return conn.connect_future 
diff --git a/contrib/python/tornado/tornado-4/tornado/wsgi.py b/contrib/python/tornado/tornado-4/tornado/wsgi.py
index 68a7615a0e..4e4631e306 100644
--- a/contrib/python/tornado/tornado-4/tornado/wsgi.py
+++ b/contrib/python/tornado/tornado-4/tornado/wsgi.py
@@ -1,358 +1,358 @@
-#!/usr/bin/env python
-#
-# Copyright 2009 Facebook
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
-
-"""WSGI support for the Tornado web framework.
-
-WSGI is the Python standard for web servers, and allows for interoperability
-between Tornado and other Python web frameworks and servers.  This module
-provides WSGI support in two ways:
-
-* `WSGIAdapter` converts a `tornado.web.Application` to the WSGI application
-  interface.  This is useful for running a Tornado app on another
-  HTTP server, such as Google App Engine.  See the `WSGIAdapter` class
-  documentation for limitations that apply.
-* `WSGIContainer` lets you run other WSGI applications and frameworks on the
-  Tornado HTTP server.  For example, with this class you can mix Django
-  and Tornado handlers in a single server.
-"""
-
-from __future__ import absolute_import, division, print_function
-
-import sys
-from io import BytesIO
-import tornado
-
-from tornado.concurrent import Future
-from tornado import escape
-from tornado import httputil
-from tornado.log import access_log
-from tornado import web
-from tornado.escape import native_str
-from tornado.util import unicode_type, PY3
-
-
-if PY3:
-    import urllib.parse as urllib_parse  # py3
-else:
-    import urllib as urllib_parse
-
-# PEP 3333 specifies that WSGI on python 3 generally deals with byte strings
-# that are smuggled inside objects of type unicode (via the latin1 encoding).
-# These functions are like those in the tornado.escape module, but defined
-# here to minimize the temptation to use them in non-wsgi contexts.
-if str is unicode_type:
-    def to_wsgi_str(s):
-        assert isinstance(s, bytes)
-        return s.decode('latin1')
-
-    def from_wsgi_str(s):
-        assert isinstance(s, str)
-        return s.encode('latin1')
-else:
-    def to_wsgi_str(s):
-        assert isinstance(s, bytes)
-        return s
-
-    def from_wsgi_str(s):
-        assert isinstance(s, str)
-        return s
-
-
-class WSGIApplication(web.Application):
-    """A WSGI equivalent of `tornado.web.Application`.
-
-    .. deprecated:: 4.0
-
-       Use a regular `.Application` and wrap it in `WSGIAdapter` instead.
-    """
-    def __call__(self, environ, start_response):
-        return WSGIAdapter(self)(environ, start_response)
-
-
-# WSGI has no facilities for flow control, so just return an already-done
-# Future when the interface requires it.
-_dummy_future = Future()
-_dummy_future.set_result(None)
-
-
-class _WSGIConnection(httputil.HTTPConnection):
-    def __init__(self, method, start_response, context):
-        self.method = method
-        self.start_response = start_response
-        self.context = context
-        self._write_buffer = []
-        self._finished = False
-        self._expected_content_remaining = None
-        self._error = None
-
-    def set_close_callback(self, callback):
-        # WSGI has no facility for detecting a closed connection mid-request,
-        # so we can simply ignore the callback.
-        pass
-
-    def write_headers(self, start_line, headers, chunk=None, callback=None):
-        if self.method == 'HEAD':
-            self._expected_content_remaining = 0
-        elif 'Content-Length' in headers:
-            self._expected_content_remaining = int(headers['Content-Length'])
-        else:
-            self._expected_content_remaining = None
-        self.start_response(
-            '%s %s' % (start_line.code, start_line.reason),
-            [(native_str(k), native_str(v)) for (k, v) in headers.get_all()])
-        if chunk is not None:
-            self.write(chunk, callback)
-        elif callback is not None:
-            callback()
-        return _dummy_future
-
-    def write(self, chunk, callback=None):
-        if self._expected_content_remaining is not None:
-            self._expected_content_remaining -= len(chunk)
-            if self._expected_content_remaining < 0:
-                self._error = httputil.HTTPOutputError(
-                    "Tried to write more data than Content-Length")
-                raise self._error
-        self._write_buffer.append(chunk)
-        if callback is not None:
-            callback()
-        return _dummy_future
-
-    def finish(self):
-        if (self._expected_content_remaining is not None and
-                self._expected_content_remaining != 0):
-            self._error = httputil.HTTPOutputError(
-                "Tried to write %d bytes less than Content-Length" %
-                self._expected_content_remaining)
-            raise self._error
-        self._finished = True
-
-
-class _WSGIRequestContext(object):
-    def __init__(self, remote_ip, protocol):
-        self.remote_ip = remote_ip
-        self.protocol = protocol
-
-    def __str__(self):
-        return self.remote_ip
-
-
-class WSGIAdapter(object):
-    """Converts a `tornado.web.Application` instance into a WSGI application.
-
-    Example usage::
-
-        import tornado.web
-        import tornado.wsgi
-        import wsgiref.simple_server
-
-        class MainHandler(tornado.web.RequestHandler):
-            def get(self):
-                self.write("Hello, world")
-
-        if __name__ == "__main__":
-            application = tornado.web.Application([
-                (r"/", MainHandler),
-            ])
-            wsgi_app = tornado.wsgi.WSGIAdapter(application)
-            server = wsgiref.simple_server.make_server('', 8888, wsgi_app)
-            server.serve_forever()
-
-    See the `appengine demo
-    <https://github.com/tornadoweb/tornado/tree/stable/demos/appengine>`_
-    for an example of using this module to run a Tornado app on Google
-    App Engine.
-
-    In WSGI mode asynchronous methods are not supported.  This means
-    that it is not possible to use `.AsyncHTTPClient`, or the
-    `tornado.auth` or `tornado.websocket` modules.
-
-    .. versionadded:: 4.0
-    """
-    def __init__(self, application):
-        if isinstance(application, WSGIApplication):
-            self.application = lambda request: web.Application.__call__(
-                application, request)
-        else:
-            self.application = application
-
-    def __call__(self, environ, start_response):
-        method = environ["REQUEST_METHOD"]
-        uri = urllib_parse.quote(from_wsgi_str(environ.get("SCRIPT_NAME", "")))
-        uri += urllib_parse.quote(from_wsgi_str(environ.get("PATH_INFO", "")))
-        if environ.get("QUERY_STRING"):
-            uri += "?" + environ["QUERY_STRING"]
-        headers = httputil.HTTPHeaders()
-        if environ.get("CONTENT_TYPE"):
-            headers["Content-Type"] = environ["CONTENT_TYPE"]
-        if environ.get("CONTENT_LENGTH"):
-            headers["Content-Length"] = environ["CONTENT_LENGTH"]
-        for key in environ:
-            if key.startswith("HTTP_"):
-                headers[key[5:].replace("_", "-")] = environ[key]
-        if headers.get("Content-Length"):
-            body = environ["wsgi.input"].read(
-                int(headers["Content-Length"]))
-        else:
-            body = b""
-        protocol = environ["wsgi.url_scheme"]
-        remote_ip = environ.get("REMOTE_ADDR", "")
-        if environ.get("HTTP_HOST"):
-            host = environ["HTTP_HOST"]
-        else:
-            host = environ["SERVER_NAME"]
-        connection = _WSGIConnection(method, start_response,
-                                     _WSGIRequestContext(remote_ip, protocol))
-        request = httputil.HTTPServerRequest(
-            method, uri, "HTTP/1.1", headers=headers, body=body,
-            host=host, connection=connection)
-        request._parse_body()
-        self.application(request)
-        if connection._error:
-            raise connection._error
-        if not connection._finished:
-            raise Exception("request did not finish synchronously")
-        return connection._write_buffer
-
-
-class WSGIContainer(object):
-    r"""Makes a WSGI-compatible function runnable on Tornado's HTTP server.
-
-    .. warning::
-
-       WSGI is a *synchronous* interface, while Tornado's concurrency model
-       is based on single-threaded asynchronous execution.  This means that
-       running a WSGI app with Tornado's `WSGIContainer` is *less scalable*
-       than running the same app in a multi-threaded WSGI server like
-       ``gunicorn`` or ``uwsgi``.  Use `WSGIContainer` only when there are
-       benefits to combining Tornado and WSGI in the same process that
-       outweigh the reduced scalability.
-
-    Wrap a WSGI function in a `WSGIContainer` and pass it to `.HTTPServer` to
-    run it. For example::
-
-        def simple_app(environ, start_response):
-            status = "200 OK"
-            response_headers = [("Content-type", "text/plain")]
-            start_response(status, response_headers)
-            return ["Hello world!\n"]
-
-        container = tornado.wsgi.WSGIContainer(simple_app)
-        http_server = tornado.httpserver.HTTPServer(container)
-        http_server.listen(8888)
-        tornado.ioloop.IOLoop.current().start()
-
-    This class is intended to let other frameworks (Django, web.py, etc)
-    run on the Tornado HTTP server and I/O loop.
-
-    The `tornado.web.FallbackHandler` class is often useful for mixing
-    Tornado and WSGI apps in the same server.  See
-    https://github.com/bdarnell/django-tornado-demo for a complete example.
-    """
-    def __init__(self, wsgi_application):
-        self.wsgi_application = wsgi_application
-
-    def __call__(self, request):
-        data = {}
-        response = []
-
-        def start_response(status, response_headers, exc_info=None):
-            data["status"] = status
-            data["headers"] = response_headers
-            return response.append
-        app_response = self.wsgi_application(
-            WSGIContainer.environ(request), start_response)
-        try:
-            response.extend(app_response)
-            body = b"".join(response)
-        finally:
-            if hasattr(app_response, "close"):
-                app_response.close()
-        if not data:
-            raise Exception("WSGI app did not call start_response")
-
-        status_code, reason = data["status"].split(' ', 1)
-        status_code = int(status_code)
-        headers = data["headers"]
-        header_set = set(k.lower() for (k, v) in headers)
-        body = escape.utf8(body)
-        if status_code != 304:
-            if "content-length" not in header_set:
-                headers.append(("Content-Length", str(len(body))))
-            if "content-type" not in header_set:
-                headers.append(("Content-Type", "text/html; charset=UTF-8"))
-        if "server" not in header_set:
-            headers.append(("Server", "TornadoServer/%s" % tornado.version))
-
-        start_line = httputil.ResponseStartLine("HTTP/1.1", status_code, reason)
-        header_obj = httputil.HTTPHeaders()
-        for key, value in headers:
-            header_obj.add(key, value)
-        request.connection.write_headers(start_line, header_obj, chunk=body)
-        request.connection.finish()
-        self._log(status_code, request)
-
-    @staticmethod
-    def environ(request):
-        """Converts a `tornado.httputil.HTTPServerRequest` to a WSGI environment.
-        """
-        hostport = request.host.split(":")
-        if len(hostport) == 2:
-            host = hostport[0]
-            port = int(hostport[1])
-        else:
-            host = request.host
-            port = 443 if request.protocol == "https" else 80
-        environ = {
-            "REQUEST_METHOD": request.method,
-            "SCRIPT_NAME": "",
-            "PATH_INFO": to_wsgi_str(escape.url_unescape(
-                request.path, encoding=None, plus=False)),
-            "QUERY_STRING": request.query,
-            "REMOTE_ADDR": request.remote_ip,
-            "SERVER_NAME": host,
-            "SERVER_PORT": str(port),
-            "SERVER_PROTOCOL": request.version,
-            "wsgi.version": (1, 0),
-            "wsgi.url_scheme": request.protocol,
-            "wsgi.input": BytesIO(escape.utf8(request.body)),
-            "wsgi.errors": sys.stderr,
-            "wsgi.multithread": False,
-            "wsgi.multiprocess": True,
-            "wsgi.run_once": False,
-        }
-        if "Content-Type" in request.headers:
-            environ["CONTENT_TYPE"] = request.headers.pop("Content-Type")
-        if "Content-Length" in request.headers:
-            environ["CONTENT_LENGTH"] = request.headers.pop("Content-Length")
-        for key, value in request.headers.items():
-            environ["HTTP_" + key.replace("-", "_").upper()] = value
-        return environ
-
-    def _log(self, status_code, request):
-        if status_code < 400:
-            log_method = access_log.info
-        elif status_code < 500:
-            log_method = access_log.warning
-        else:
-            log_method = access_log.error
-        request_time = 1000.0 * request.request_time()
-        summary = request.method + " " + request.uri + " (" + \
-            request.remote_ip + ")"
-        log_method("%d %s %.2fms", status_code, summary, request_time)
-
-
-HTTPRequest = httputil.HTTPServerRequest
+#!/usr/bin/env python 
+# 
+# Copyright 2009 Facebook 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may 
+# not use this file except in compliance with the License. You may obtain 
+# a copy of the License at 
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0 
+# 
+# Unless required by applicable law or agreed to in writing, software 
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
+# License for the specific language governing permissions and limitations 
+# under the License. 
+ 
+"""WSGI support for the Tornado web framework. 
+ 
+WSGI is the Python standard for web servers, and allows for interoperability 
+between Tornado and other Python web frameworks and servers.  This module 
+provides WSGI support in two ways: 
+ 
+* `WSGIAdapter` converts a `tornado.web.Application` to the WSGI application 
+  interface.  This is useful for running a Tornado app on another 
+  HTTP server, such as Google App Engine.  See the `WSGIAdapter` class 
+  documentation for limitations that apply. 
+* `WSGIContainer` lets you run other WSGI applications and frameworks on the 
+  Tornado HTTP server.  For example, with this class you can mix Django 
+  and Tornado handlers in a single server. 
+""" 
+ 
+from __future__ import absolute_import, division, print_function 
+ 
+import sys 
+from io import BytesIO 
+import tornado 
+ 
+from tornado.concurrent import Future 
+from tornado import escape 
+from tornado import httputil 
+from tornado.log import access_log 
+from tornado import web 
+from tornado.escape import native_str 
+from tornado.util import unicode_type, PY3 
+ 
+ 
+if PY3: 
+    import urllib.parse as urllib_parse  # py3 
+else: 
+    import urllib as urllib_parse 
+ 
+# PEP 3333 specifies that WSGI on python 3 generally deals with byte strings 
+# that are smuggled inside objects of type unicode (via the latin1 encoding). 
+# These functions are like those in the tornado.escape module, but defined 
+# here to minimize the temptation to use them in non-wsgi contexts. 
+if str is unicode_type: 
+    def to_wsgi_str(s): 
+        assert isinstance(s, bytes) 
+        return s.decode('latin1') 
+ 
+    def from_wsgi_str(s): 
+        assert isinstance(s, str) 
+        return s.encode('latin1') 
+else: 
+    def to_wsgi_str(s): 
+        assert isinstance(s, bytes) 
+        return s 
+ 
+    def from_wsgi_str(s): 
+        assert isinstance(s, str) 
+        return s 
+ 
+ 
+class WSGIApplication(web.Application): 
+    """A WSGI equivalent of `tornado.web.Application`. 
+ 
+    .. deprecated:: 4.0 
+ 
+       Use a regular `.Application` and wrap it in `WSGIAdapter` instead. 
+    """ 
+    def __call__(self, environ, start_response): 
+        return WSGIAdapter(self)(environ, start_response) 
+ 
+ 
+# WSGI has no facilities for flow control, so just return an already-done 
+# Future when the interface requires it. 
+_dummy_future = Future() 
+_dummy_future.set_result(None) 
+ 
+ 
+class _WSGIConnection(httputil.HTTPConnection): 
+    def __init__(self, method, start_response, context): 
+        self.method = method 
+        self.start_response = start_response 
+        self.context = context 
+        self._write_buffer = [] 
+        self._finished = False 
+        self._expected_content_remaining = None 
+        self._error = None 
+ 
+    def set_close_callback(self, callback): 
+        # WSGI has no facility for detecting a closed connection mid-request, 
+        # so we can simply ignore the callback. 
+        pass 
+ 
+    def write_headers(self, start_line, headers, chunk=None, callback=None): 
+        if self.method == 'HEAD': 
+            self._expected_content_remaining = 0 
+        elif 'Content-Length' in headers: 
+            self._expected_content_remaining = int(headers['Content-Length']) 
+        else: 
+            self._expected_content_remaining = None 
+        self.start_response( 
+            '%s %s' % (start_line.code, start_line.reason), 
+            [(native_str(k), native_str(v)) for (k, v) in headers.get_all()]) 
+        if chunk is not None: 
+            self.write(chunk, callback) 
+        elif callback is not None: 
+            callback() 
+        return _dummy_future 
+ 
+    def write(self, chunk, callback=None): 
+        if self._expected_content_remaining is not None: 
+            self._expected_content_remaining -= len(chunk) 
+            if self._expected_content_remaining < 0: 
+                self._error = httputil.HTTPOutputError( 
+                    "Tried to write more data than Content-Length") 
+                raise self._error 
+        self._write_buffer.append(chunk) 
+        if callback is not None: 
+            callback() 
+        return _dummy_future 
+ 
+    def finish(self): 
+        if (self._expected_content_remaining is not None and 
+                self._expected_content_remaining != 0): 
+            self._error = httputil.HTTPOutputError( 
+                "Tried to write %d bytes less than Content-Length" % 
+                self._expected_content_remaining) 
+            raise self._error 
+        self._finished = True 
+ 
+ 
+class _WSGIRequestContext(object): 
+    def __init__(self, remote_ip, protocol): 
+        self.remote_ip = remote_ip 
+        self.protocol = protocol 
+ 
+    def __str__(self): 
+        return self.remote_ip 
+ 
+ 
+class WSGIAdapter(object): 
+    """Converts a `tornado.web.Application` instance into a WSGI application. 
+ 
+    Example usage:: 
+ 
+        import tornado.web 
+        import tornado.wsgi 
+        import wsgiref.simple_server 
+ 
+        class MainHandler(tornado.web.RequestHandler): 
+            def get(self): 
+                self.write("Hello, world") 
+ 
+        if __name__ == "__main__": 
+            application = tornado.web.Application([ 
+                (r"/", MainHandler), 
+            ]) 
+            wsgi_app = tornado.wsgi.WSGIAdapter(application) 
+            server = wsgiref.simple_server.make_server('', 8888, wsgi_app) 
+            server.serve_forever() 
+ 
+    See the `appengine demo 
+    <https://github.com/tornadoweb/tornado/tree/stable/demos/appengine>`_ 
+    for an example of using this module to run a Tornado app on Google 
+    App Engine. 
+ 
+    In WSGI mode asynchronous methods are not supported.  This means 
+    that it is not possible to use `.AsyncHTTPClient`, or the 
+    `tornado.auth` or `tornado.websocket` modules. 
+ 
+    .. versionadded:: 4.0 
+    """ 
+    def __init__(self, application): 
+        if isinstance(application, WSGIApplication): 
+            self.application = lambda request: web.Application.__call__( 
+                application, request) 
+        else: 
+            self.application = application 
+ 
+    def __call__(self, environ, start_response): 
+        method = environ["REQUEST_METHOD"] 
+        uri = urllib_parse.quote(from_wsgi_str(environ.get("SCRIPT_NAME", ""))) 
+        uri += urllib_parse.quote(from_wsgi_str(environ.get("PATH_INFO", ""))) 
+        if environ.get("QUERY_STRING"): 
+            uri += "?" + environ["QUERY_STRING"] 
+        headers = httputil.HTTPHeaders() 
+        if environ.get("CONTENT_TYPE"): 
+            headers["Content-Type"] = environ["CONTENT_TYPE"] 
+        if environ.get("CONTENT_LENGTH"): 
+            headers["Content-Length"] = environ["CONTENT_LENGTH"] 
+        for key in environ: 
+            if key.startswith("HTTP_"): 
+                headers[key[5:].replace("_", "-")] = environ[key] 
+        if headers.get("Content-Length"): 
+            body = environ["wsgi.input"].read( 
+                int(headers["Content-Length"])) 
+        else: 
+            body = b"" 
+        protocol = environ["wsgi.url_scheme"] 
+        remote_ip = environ.get("REMOTE_ADDR", "") 
+        if environ.get("HTTP_HOST"): 
+            host = environ["HTTP_HOST"] 
+        else: 
+            host = environ["SERVER_NAME"] 
+        connection = _WSGIConnection(method, start_response, 
+                                     _WSGIRequestContext(remote_ip, protocol)) 
+        request = httputil.HTTPServerRequest( 
+            method, uri, "HTTP/1.1", headers=headers, body=body, 
+            host=host, connection=connection) 
+        request._parse_body() 
+        self.application(request) 
+        if connection._error: 
+            raise connection._error 
+        if not connection._finished: 
+            raise Exception("request did not finish synchronously") 
+        return connection._write_buffer 
+ 
+ 
+class WSGIContainer(object): 
+    r"""Makes a WSGI-compatible function runnable on Tornado's HTTP server. 
+ 
+    .. warning:: 
+ 
+       WSGI is a *synchronous* interface, while Tornado's concurrency model 
+       is based on single-threaded asynchronous execution.  This means that 
+       running a WSGI app with Tornado's `WSGIContainer` is *less scalable* 
+       than running the same app in a multi-threaded WSGI server like 
+       ``gunicorn`` or ``uwsgi``.  Use `WSGIContainer` only when there are 
+       benefits to combining Tornado and WSGI in the same process that 
+       outweigh the reduced scalability. 
+ 
+    Wrap a WSGI function in a `WSGIContainer` and pass it to `.HTTPServer` to 
+    run it. For example:: 
+ 
+        def simple_app(environ, start_response): 
+            status = "200 OK" 
+            response_headers = [("Content-type", "text/plain")] 
+            start_response(status, response_headers) 
+            return ["Hello world!\n"] 
+ 
+        container = tornado.wsgi.WSGIContainer(simple_app) 
+        http_server = tornado.httpserver.HTTPServer(container) 
+        http_server.listen(8888) 
+        tornado.ioloop.IOLoop.current().start() 
+ 
+    This class is intended to let other frameworks (Django, web.py, etc) 
+    run on the Tornado HTTP server and I/O loop. 
+ 
+    The `tornado.web.FallbackHandler` class is often useful for mixing 
+    Tornado and WSGI apps in the same server.  See 
+    https://github.com/bdarnell/django-tornado-demo for a complete example. 
+    """ 
+    def __init__(self, wsgi_application): 
+        self.wsgi_application = wsgi_application 
+ 
+    def __call__(self, request): 
+        data = {} 
+        response = [] 
+ 
+        def start_response(status, response_headers, exc_info=None): 
+            data["status"] = status 
+            data["headers"] = response_headers 
+            return response.append 
+        app_response = self.wsgi_application( 
+            WSGIContainer.environ(request), start_response) 
+        try: 
+            response.extend(app_response) 
+            body = b"".join(response) 
+        finally: 
+            if hasattr(app_response, "close"): 
+                app_response.close() 
+        if not data: 
+            raise Exception("WSGI app did not call start_response") 
+ 
+        status_code, reason = data["status"].split(' ', 1) 
+        status_code = int(status_code) 
+        headers = data["headers"] 
+        header_set = set(k.lower() for (k, v) in headers) 
+        body = escape.utf8(body) 
+        if status_code != 304: 
+            if "content-length" not in header_set: 
+                headers.append(("Content-Length", str(len(body)))) 
+            if "content-type" not in header_set: 
+                headers.append(("Content-Type", "text/html; charset=UTF-8")) 
+        if "server" not in header_set: 
+            headers.append(("Server", "TornadoServer/%s" % tornado.version)) 
+ 
+        start_line = httputil.ResponseStartLine("HTTP/1.1", status_code, reason) 
+        header_obj = httputil.HTTPHeaders() 
+        for key, value in headers: 
+            header_obj.add(key, value) 
+        request.connection.write_headers(start_line, header_obj, chunk=body) 
+        request.connection.finish() 
+        self._log(status_code, request) 
+ 
+    @staticmethod 
+    def environ(request): 
+        """Converts a `tornado.httputil.HTTPServerRequest` to a WSGI environment. 
+        """ 
+        hostport = request.host.split(":") 
+        if len(hostport) == 2: 
+            host = hostport[0] 
+            port = int(hostport[1]) 
+        else: 
+            host = request.host 
+            port = 443 if request.protocol == "https" else 80 
+        environ = { 
+            "REQUEST_METHOD": request.method, 
+            "SCRIPT_NAME": "", 
+            "PATH_INFO": to_wsgi_str(escape.url_unescape( 
+                request.path, encoding=None, plus=False)), 
+            "QUERY_STRING": request.query, 
+            "REMOTE_ADDR": request.remote_ip, 
+            "SERVER_NAME": host, 
+            "SERVER_PORT": str(port), 
+            "SERVER_PROTOCOL": request.version, 
+            "wsgi.version": (1, 0), 
+            "wsgi.url_scheme": request.protocol, 
+            "wsgi.input": BytesIO(escape.utf8(request.body)), 
+            "wsgi.errors": sys.stderr, 
+            "wsgi.multithread": False, 
+            "wsgi.multiprocess": True, 
+            "wsgi.run_once": False, 
+        } 
+        if "Content-Type" in request.headers: 
+            environ["CONTENT_TYPE"] = request.headers.pop("Content-Type") 
+        if "Content-Length" in request.headers: 
+            environ["CONTENT_LENGTH"] = request.headers.pop("Content-Length") 
+        for key, value in request.headers.items(): 
+            environ["HTTP_" + key.replace("-", "_").upper()] = value 
+        return environ 
+ 
+    def _log(self, status_code, request): 
+        if status_code < 400: 
+            log_method = access_log.info 
+        elif status_code < 500: 
+            log_method = access_log.warning 
+        else: 
+            log_method = access_log.error 
+        request_time = 1000.0 * request.request_time() 
+        summary = request.method + " " + request.uri + " (" + \ 
+            request.remote_ip + ")" 
+        log_method("%d %s %.2fms", status_code, summary, request_time) 
+ 
+ 
+HTTPRequest = httputil.HTTPServerRequest 
diff --git a/contrib/python/tornado/tornado-4/tornado/ya.make b/contrib/python/tornado/tornado-4/tornado/ya.make
index 195c1fad93..c960eea835 100644
--- a/contrib/python/tornado/tornado-4/tornado/ya.make
+++ b/contrib/python/tornado/tornado-4/tornado/ya.make
@@ -1 +1 @@
-OWNER(g:python-contrib)
+OWNER(g:python-contrib) 
diff --git a/contrib/python/tornado/tornado-4/ya.make b/contrib/python/tornado/tornado-4/ya.make
index 0ea2ed6040..1efad04639 100644
--- a/contrib/python/tornado/tornado-4/ya.make
+++ b/contrib/python/tornado/tornado-4/ya.make
@@ -1,84 +1,84 @@
-OWNER(g:python-contrib dldmitry orivej)
-
-PY23_LIBRARY()
-
-LICENSE(Apache-2.0)
-
-VERSION(4.5.3)
-
+OWNER(g:python-contrib dldmitry orivej) 
+ 
+PY23_LIBRARY() 
+ 
+LICENSE(Apache-2.0) 
+ 
+VERSION(4.5.3) 
+ 
 PROVIDES(tornado)
 
-PEERDIR(
-    # because of ca bundle
-    contrib/python/certifi
-)
-
-IF (PYTHON2)
-    PEERDIR(
-        contrib/python/backports_abc
-        contrib/python/singledispatch
-    )
-ENDIF()
-
-NO_CHECK_IMPORTS(
-    tornado.platform.*
-    tornado.curl_httpclient
-)
-
-NO_LINT()
-
-PY_SRCS(
-    TOP_LEVEL
-    tornado/__init__.py
-    tornado/_locale_data.py
-    tornado/auth.py
-    tornado/autoreload.py
-    tornado/concurrent.py
-    tornado/curl_httpclient.py
-    tornado/escape.py
-    tornado/gen.py
-    tornado/http1connection.py
-    tornado/httpclient.py
-    tornado/httpserver.py
-    tornado/httputil.py
-    tornado/ioloop.py
-    tornado/iostream.py
-    tornado/locale.py
-    tornado/locks.py
-    tornado/log.py
-    tornado/netutil.py
-    tornado/options.py
-    tornado/platform/__init__.py
-    tornado/platform/asyncio.py
-    tornado/platform/auto.py
-    tornado/platform/caresresolver.py
-    tornado/platform/common.py
-    tornado/platform/epoll.py
-    tornado/platform/interface.py
-    tornado/platform/kqueue.py
-    tornado/platform/posix.py
-    tornado/platform/select.py
-    tornado/platform/twisted.py
-    tornado/platform/windows.py
-    tornado/process.py
-    tornado/queues.py
-    tornado/routing.py
-    tornado/simple_httpclient.py
-    tornado/stack_context.py
-    tornado/tcpclient.py
-    tornado/tcpserver.py
-    tornado/template.py
-    tornado/testing.py
-    tornado/util.py
-    tornado/web.py
-    tornado/websocket.py
-    tornado/wsgi.py
-)
-
-RESOURCE_FILES(
-    PREFIX contrib/python/tornado/tornado-4/
-    .dist-info/METADATA
-    .dist-info/top_level.txt
-)
-
-END()
+PEERDIR( 
+    # because of ca bundle 
+    contrib/python/certifi 
+) 
+ 
+IF (PYTHON2) 
+    PEERDIR( 
+        contrib/python/backports_abc 
+        contrib/python/singledispatch 
+    ) 
+ENDIF() 
+ 
+NO_CHECK_IMPORTS( 
+    tornado.platform.* 
+    tornado.curl_httpclient 
+) 
+ 
+NO_LINT() 
+ 
+PY_SRCS( 
+    TOP_LEVEL 
+    tornado/__init__.py 
+    tornado/_locale_data.py 
+    tornado/auth.py 
+    tornado/autoreload.py 
+    tornado/concurrent.py 
+    tornado/curl_httpclient.py 
+    tornado/escape.py 
+    tornado/gen.py 
+    tornado/http1connection.py 
+    tornado/httpclient.py 
+    tornado/httpserver.py 
+    tornado/httputil.py 
+    tornado/ioloop.py 
+    tornado/iostream.py 
+    tornado/locale.py 
+    tornado/locks.py 
+    tornado/log.py 
+    tornado/netutil.py 
+    tornado/options.py 
+    tornado/platform/__init__.py 
+    tornado/platform/asyncio.py 
+    tornado/platform/auto.py 
+    tornado/platform/caresresolver.py 
+    tornado/platform/common.py 
+    tornado/platform/epoll.py 
+    tornado/platform/interface.py 
+    tornado/platform/kqueue.py 
+    tornado/platform/posix.py 
+    tornado/platform/select.py 
+    tornado/platform/twisted.py 
+    tornado/platform/windows.py 
+    tornado/process.py 
+    tornado/queues.py 
+    tornado/routing.py 
+    tornado/simple_httpclient.py 
+    tornado/stack_context.py 
+    tornado/tcpclient.py 
+    tornado/tcpserver.py 
+    tornado/template.py 
+    tornado/testing.py 
+    tornado/util.py 
+    tornado/web.py 
+    tornado/websocket.py 
+    tornado/wsgi.py 
+) 
+ 
+RESOURCE_FILES( 
+    PREFIX contrib/python/tornado/tornado-4/ 
+    .dist-info/METADATA 
+    .dist-info/top_level.txt 
+) 
+ 
+END() 
diff --git a/contrib/python/tornado/ya.make b/contrib/python/tornado/ya.make
index 85a91fb7c1..796f54155f 100644
--- a/contrib/python/tornado/ya.make
+++ b/contrib/python/tornado/ya.make
@@ -14,7 +14,7 @@ NO_LINT()
 
 END()
 
-RECURSE(
-    tornado-4
-    tornado-6
+RECURSE( 
+    tornado-4 
+    tornado-6 
 )