intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

51 files changed, 23739 insertions, 0 deletions

diff --git a/contrib/python/tornado/tornado-4/.dist-info/METADATA b/contrib/python/tornado/tornado-4/.dist-info/METADATA
new file mode 100644
index 0000000000..3c02bd9be2
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/.dist-info/METADATA
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/.dist-info/top_level.txt b/contrib/python/tornado/tornado-4/.dist-info/top_level.txt
new file mode 100644
index 0000000000..c3368dfa51
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/.dist-info/top_level.txt
@@ -0,0 +1 @@
+tornado
diff --git a/contrib/python/tornado/tornado-4/tornado/__init__.py b/contrib/python/tornado/tornado-4/tornado/__init__.py
new file mode 100644
index 0000000000..fa71bf6133
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/__init__.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/_locale_data.py b/contrib/python/tornado/tornado-4/tornado/_locale_data.py
new file mode 100644
index 0000000000..6fa2c29742
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/_locale_data.py
@@ -0,0 +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)"},
+}
diff --git a/contrib/python/tornado/tornado-4/tornado/auth.py b/contrib/python/tornado/tornado-4/tornado/auth.py
new file mode 100644
index 0000000000..f02d289808
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/auth.py
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/tornado/autoreload.py b/contrib/python/tornado/tornado-4/tornado/autoreload.py
new file mode 100644
index 0000000000..60571efe71
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/autoreload.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/concurrent.py b/contrib/python/tornado/tornado-4/tornado/concurrent.py
new file mode 100644
index 0000000000..667e6b1788
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/concurrent.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/curl_httpclient.py b/contrib/python/tornado/tornado-4/tornado/curl_httpclient.py
new file mode 100644
index 0000000000..28492c16cd
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/curl_httpclient.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/escape.py b/contrib/python/tornado/tornado-4/tornado/escape.py
new file mode 100644
index 0000000000..2ca3fe3fe8
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/escape.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/gen.py b/contrib/python/tornado/tornado-4/tornado/gen.py
new file mode 100644
index 0000000000..89a4dd7c7a
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/gen.py
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/tornado/http1connection.py b/contrib/python/tornado/tornado-4/tornado/http1connection.py
new file mode 100644
index 0000000000..32bed6c961
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/http1connection.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/httpclient.py b/contrib/python/tornado/tornado-4/tornado/httpclient.py
new file mode 100644
index 0000000000..8436ece469
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/httpclient.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/httpserver.py b/contrib/python/tornado/tornado-4/tornado/httpserver.py
new file mode 100644
index 0000000000..d757be188d
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/httpserver.py
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/tornado/httputil.py b/contrib/python/tornado/tornado-4/tornado/httputil.py
new file mode 100644
index 0000000000..9654b5ab4b
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/httputil.py
@@ -0,0 +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
+
+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)
+
+
+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
diff --git a/contrib/python/tornado/tornado-4/tornado/ioloop.py b/contrib/python/tornado/tornado-4/tornado/ioloop.py
new file mode 100644
index 0000000000..ad35787fca
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/ioloop.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/iostream.py b/contrib/python/tornado/tornado-4/tornado/iostream.py
new file mode 100644
index 0000000000..639ed5082b
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/iostream.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/locale.py b/contrib/python/tornado/tornado-4/tornado/locale.py
new file mode 100644
index 0000000000..7dba10d616
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/locale.py
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/tornado/locks.py b/contrib/python/tornado/tornado-4/tornado/locks.py
new file mode 100644
index 0000000000..4f9ecf6dfd
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/locks.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/log.py b/contrib/python/tornado/tornado-4/tornado/log.py
new file mode 100644
index 0000000000..654afc021e
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/log.py
@@ -0,0 +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))
diff --git a/contrib/python/tornado/tornado-4/tornado/netutil.py b/contrib/python/tornado/tornado-4/tornado/netutil.py
new file mode 100644
index 0000000000..59df1435ea
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/netutil.py
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/tornado/options.py b/contrib/python/tornado/tornado-4/tornado/options.py
new file mode 100644
index 0000000000..707fbd35ee
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/options.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/__init__.py b/contrib/python/tornado/tornado-4/tornado/platform/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/__init__.py
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/asyncio.py b/contrib/python/tornado/tornado-4/tornado/platform/asyncio.py
new file mode 100644
index 0000000000..830ee1f3b1
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/asyncio.py
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/auto.py b/contrib/python/tornado/tornado-4/tornado/platform/auto.py
new file mode 100644
index 0000000000..1f4d700193
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/auto.py
@@ -0,0 +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']
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/caresresolver.py b/contrib/python/tornado/tornado-4/tornado/platform/caresresolver.py
new file mode 100644
index 0000000000..fd6e9d2748
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/caresresolver.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/common.py b/contrib/python/tornado/tornado-4/tornado/platform/common.py
new file mode 100644
index 0000000000..b597748d1f
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/common.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/epoll.py b/contrib/python/tornado/tornado-4/tornado/platform/epoll.py
new file mode 100644
index 0000000000..80bfd8af4c
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/epoll.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/interface.py b/contrib/python/tornado/tornado-4/tornado/platform/interface.py
new file mode 100644
index 0000000000..c0ef2905c3
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/interface.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/kqueue.py b/contrib/python/tornado/tornado-4/tornado/platform/kqueue.py
new file mode 100644
index 0000000000..3a5d417429
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/kqueue.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/posix.py b/contrib/python/tornado/tornado-4/tornado/platform/posix.py
new file mode 100644
index 0000000000..9bf1f18868
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/posix.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/select.py b/contrib/python/tornado/tornado-4/tornado/platform/select.py
new file mode 100644
index 0000000000..a18049f7cd
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/select.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/twisted.py b/contrib/python/tornado/tornado-4/tornado/platform/twisted.py
new file mode 100644
index 0000000000..0f9787e84d
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/twisted.py
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/windows.py b/contrib/python/tornado/tornado-4/tornado/platform/windows.py
new file mode 100644
index 0000000000..e94a0cf13d
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/windows.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/platform/ya.make b/contrib/python/tornado/tornado-4/tornado/platform/ya.make
new file mode 100644
index 0000000000..195c1fad93
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/platform/ya.make
@@ -0,0 +1 @@
+OWNER(g:python-contrib)
diff --git a/contrib/python/tornado/tornado-4/tornado/process.py b/contrib/python/tornado/tornado-4/tornado/process.py
new file mode 100644
index 0000000000..fae94f3c13
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/process.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/queues.py b/contrib/python/tornado/tornado-4/tornado/queues.py
new file mode 100644
index 0000000000..0041a80086
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/queues.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/routing.py b/contrib/python/tornado/tornado-4/tornado/routing.py
new file mode 100644
index 0000000000..6762dc05bc
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/routing.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/simple_httpclient.py b/contrib/python/tornado/tornado-4/tornado/simple_httpclient.py
new file mode 100644
index 0000000000..8fb70707f9
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/simple_httpclient.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/speedups.c b/contrib/python/tornado/tornado-4/tornado/speedups.c
new file mode 100644
index 0000000000..c59bda0092
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/speedups.c
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/tornado/stack_context.py b/contrib/python/tornado/tornado-4/tornado/stack_context.py
new file mode 100644
index 0000000000..61ae51f4eb
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/stack_context.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/tcpclient.py b/contrib/python/tornado/tornado-4/tornado/tcpclient.py
new file mode 100644
index 0000000000..bb5e9f347e
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/tcpclient.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/tcpserver.py b/contrib/python/tornado/tornado-4/tornado/tcpserver.py
new file mode 100644
index 0000000000..f47ec89a42
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/tcpserver.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/template.py b/contrib/python/tornado/tornado-4/tornado/template.py
new file mode 100644
index 0000000000..3b2fa3feef
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/template.py
@@ -0,0 +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)
diff --git a/contrib/python/tornado/tornado-4/tornado/testing.py b/contrib/python/tornado/tornado-4/tornado/testing.py
new file mode 100644
index 0000000000..82a3b93732
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/testing.py
@@ -0,0 +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.
+    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()
diff --git a/contrib/python/tornado/tornado-4/tornado/util.py b/contrib/python/tornado/tornado-4/tornado/util.py
new file mode 100644
index 0000000000..981b94c8ea
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/util.py
@@ -0,0 +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()
diff --git a/contrib/python/tornado/tornado-4/tornado/web.py b/contrib/python/tornado/tornado-4/tornado/web.py
new file mode 100644
index 0000000000..e8d102b50e
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/web.py
@@ -0,0 +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:"])
diff --git a/contrib/python/tornado/tornado-4/tornado/websocket.py b/contrib/python/tornado/tornado-4/tornado/websocket.py
new file mode 100644
index 0000000000..0e9d339f59
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/websocket.py
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/tornado/wsgi.py b/contrib/python/tornado/tornado-4/tornado/wsgi.py
new file mode 100644
index 0000000000..68a7615a0e
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/wsgi.py
@@ -0,0 +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
diff --git a/contrib/python/tornado/tornado-4/tornado/ya.make b/contrib/python/tornado/tornado-4/tornado/ya.make
new file mode 100644
index 0000000000..195c1fad93
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/tornado/ya.make
@@ -0,0 +1 @@
+OWNER(g:python-contrib)
diff --git a/contrib/python/tornado/tornado-4/ya.make b/contrib/python/tornado/tornado-4/ya.make
new file mode 100644
index 0000000000..0ea2ed6040
--- /dev/null
+++ b/contrib/python/tornado/tornado-4/ya.make
@@ -0,0 +1,84 @@
+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()
diff --git a/contrib/python/tornado/ya.make b/contrib/python/tornado/ya.make
new file mode 100644
index 0000000000..85a91fb7c1
--- /dev/null
+++ b/contrib/python/tornado/ya.make
@@ -0,0 +1,20 @@
+PY23_LIBRARY()
+
+LICENSE(Service-Py23-Proxy)
+
+OWNER(g:python-contrib)
+
+IF (PYTHON2)
+    PEERDIR(contrib/python/tornado/tornado-4)
+ELSE()
+    PEERDIR(contrib/python/tornado/tornado-6)
+ENDIF()
+
+NO_LINT()
+
+END()
+
+RECURSE(
+    tornado-4
+    tornado-6
+)