Library import 16 (#2433)

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1 files changed, 1609 insertions, 0 deletions

diff --git a/contrib/tools/python3/Lib/logging/handlers.py b/contrib/tools/python3/Lib/logging/handlers.py
new file mode 100644
index 0000000000..6e88184b51
--- /dev/null
+++ b/contrib/tools/python3/Lib/logging/handlers.py
@@ -0,0 +1,1609 @@
+# Copyright 2001-2021 by Vinay Sajip. All Rights Reserved.
+#
+# Permission to use, copy, modify, and distribute this software and its
+# documentation for any purpose and without fee is hereby granted,
+# provided that the above copyright notice appear in all copies and that
+# both that copyright notice and this permission notice appear in
+# supporting documentation, and that the name of Vinay Sajip
+# not be used in advertising or publicity pertaining to distribution
+# of the software without specific, written prior permission.
+# VINAY SAJIP DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
+# ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
+# VINAY SAJIP BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
+# ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
+# IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
+# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+"""
+Additional handlers for the logging package for Python. The core package is
+based on PEP 282 and comments thereto in comp.lang.python.
+
+Copyright (C) 2001-2021 Vinay Sajip. All Rights Reserved.
+
+To use, simply 'import logging.handlers' and log away!
+"""
+
+import io, logging, socket, os, pickle, struct, time, re
+from stat import ST_DEV, ST_INO, ST_MTIME
+import queue
+import threading
+import copy
+
+#
+# Some constants...
+#
+
+DEFAULT_TCP_LOGGING_PORT    = 9020
+DEFAULT_UDP_LOGGING_PORT    = 9021
+DEFAULT_HTTP_LOGGING_PORT   = 9022
+DEFAULT_SOAP_LOGGING_PORT   = 9023
+SYSLOG_UDP_PORT             = 514
+SYSLOG_TCP_PORT             = 514
+
+_MIDNIGHT = 24 * 60 * 60  # number of seconds in a day
+
+class BaseRotatingHandler(logging.FileHandler):
+    """
+    Base class for handlers that rotate log files at a certain point.
+    Not meant to be instantiated directly.  Instead, use RotatingFileHandler
+    or TimedRotatingFileHandler.
+    """
+    namer = None
+    rotator = None
+
+    def __init__(self, filename, mode, encoding=None, delay=False, errors=None):
+        """
+        Use the specified filename for streamed logging
+        """
+        logging.FileHandler.__init__(self, filename, mode=mode,
+                                     encoding=encoding, delay=delay,
+                                     errors=errors)
+        self.mode = mode
+        self.encoding = encoding
+        self.errors = errors
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        Output the record to the file, catering for rollover as described
+        in doRollover().
+        """
+        try:
+            if self.shouldRollover(record):
+                self.doRollover()
+            logging.FileHandler.emit(self, record)
+        except Exception:
+            self.handleError(record)
+
+    def rotation_filename(self, default_name):
+        """
+        Modify the filename of a log file when rotating.
+
+        This is provided so that a custom filename can be provided.
+
+        The default implementation calls the 'namer' attribute of the
+        handler, if it's callable, passing the default name to
+        it. If the attribute isn't callable (the default is None), the name
+        is returned unchanged.
+
+        :param default_name: The default name for the log file.
+        """
+        if not callable(self.namer):
+            result = default_name
+        else:
+            result = self.namer(default_name)
+        return result
+
+    def rotate(self, source, dest):
+        """
+        When rotating, rotate the current log.
+
+        The default implementation calls the 'rotator' attribute of the
+        handler, if it's callable, passing the source and dest arguments to
+        it. If the attribute isn't callable (the default is None), the source
+        is simply renamed to the destination.
+
+        :param source: The source filename. This is normally the base
+                       filename, e.g. 'test.log'
+        :param dest:   The destination filename. This is normally
+                       what the source is rotated to, e.g. 'test.log.1'.
+        """
+        if not callable(self.rotator):
+            # Issue 18940: A file may not have been created if delay is True.
+            if os.path.exists(source):
+                os.rename(source, dest)
+        else:
+            self.rotator(source, dest)
+
+class RotatingFileHandler(BaseRotatingHandler):
+    """
+    Handler for logging to a set of files, which switches from one file
+    to the next when the current file reaches a certain size.
+    """
+    def __init__(self, filename, mode='a', maxBytes=0, backupCount=0,
+                 encoding=None, delay=False, errors=None):
+        """
+        Open the specified file and use it as the stream for logging.
+
+        By default, the file grows indefinitely. You can specify particular
+        values of maxBytes and backupCount to allow the file to rollover at
+        a predetermined size.
+
+        Rollover occurs whenever the current log file is nearly maxBytes in
+        length. If backupCount is >= 1, the system will successively create
+        new files with the same pathname as the base file, but with extensions
+        ".1", ".2" etc. appended to it. For example, with a backupCount of 5
+        and a base file name of "app.log", you would get "app.log",
+        "app.log.1", "app.log.2", ... through to "app.log.5". The file being
+        written to is always "app.log" - when it gets filled up, it is closed
+        and renamed to "app.log.1", and if files "app.log.1", "app.log.2" etc.
+        exist, then they are renamed to "app.log.2", "app.log.3" etc.
+        respectively.
+
+        If maxBytes is zero, rollover never occurs.
+        """
+        # If rotation/rollover is wanted, it doesn't make sense to use another
+        # mode. If for example 'w' were specified, then if there were multiple
+        # runs of the calling application, the logs from previous runs would be
+        # lost if the 'w' is respected, because the log file would be truncated
+        # on each run.
+        if maxBytes > 0:
+            mode = 'a'
+        if "b" not in mode:
+            encoding = io.text_encoding(encoding)
+        BaseRotatingHandler.__init__(self, filename, mode, encoding=encoding,
+                                     delay=delay, errors=errors)
+        self.maxBytes = maxBytes
+        self.backupCount = backupCount
+
+    def doRollover(self):
+        """
+        Do a rollover, as described in __init__().
+        """
+        if self.stream:
+            self.stream.close()
+            self.stream = None
+        if self.backupCount > 0:
+            for i in range(self.backupCount - 1, 0, -1):
+                sfn = self.rotation_filename("%s.%d" % (self.baseFilename, i))
+                dfn = self.rotation_filename("%s.%d" % (self.baseFilename,
+                                                        i + 1))
+                if os.path.exists(sfn):
+                    if os.path.exists(dfn):
+                        os.remove(dfn)
+                    os.rename(sfn, dfn)
+            dfn = self.rotation_filename(self.baseFilename + ".1")
+            if os.path.exists(dfn):
+                os.remove(dfn)
+            self.rotate(self.baseFilename, dfn)
+        if not self.delay:
+            self.stream = self._open()
+
+    def shouldRollover(self, record):
+        """
+        Determine if rollover should occur.
+
+        Basically, see if the supplied record would cause the file to exceed
+        the size limit we have.
+        """
+        # See bpo-45401: Never rollover anything other than regular files
+        if os.path.exists(self.baseFilename) and not os.path.isfile(self.baseFilename):
+            return False
+        if self.stream is None:                 # delay was set...
+            self.stream = self._open()
+        if self.maxBytes > 0:                   # are we rolling over?
+            msg = "%s\n" % self.format(record)
+            self.stream.seek(0, 2)  #due to non-posix-compliant Windows feature
+            if self.stream.tell() + len(msg) >= self.maxBytes:
+                return True
+        return False
+
+class TimedRotatingFileHandler(BaseRotatingHandler):
+    """
+    Handler for logging to a file, rotating the log file at certain timed
+    intervals.
+
+    If backupCount is > 0, when rollover is done, no more than backupCount
+    files are kept - the oldest ones are deleted.
+    """
+    def __init__(self, filename, when='h', interval=1, backupCount=0,
+                 encoding=None, delay=False, utc=False, atTime=None,
+                 errors=None):
+        encoding = io.text_encoding(encoding)
+        BaseRotatingHandler.__init__(self, filename, 'a', encoding=encoding,
+                                     delay=delay, errors=errors)
+        self.when = when.upper()
+        self.backupCount = backupCount
+        self.utc = utc
+        self.atTime = atTime
+        # Calculate the real rollover interval, which is just the number of
+        # seconds between rollovers.  Also set the filename suffix used when
+        # a rollover occurs.  Current 'when' events supported:
+        # S - Seconds
+        # M - Minutes
+        # H - Hours
+        # D - Days
+        # midnight - roll over at midnight
+        # W{0-6} - roll over on a certain day; 0 - Monday
+        #
+        # Case of the 'when' specifier is not important; lower or upper case
+        # will work.
+        if self.when == 'S':
+            self.interval = 1 # one second
+            self.suffix = "%Y-%m-%d_%H-%M-%S"
+            self.extMatch = r"^\d{4}-\d{2}-\d{2}_\d{2}-\d{2}-\d{2}(\.\w+)?$"
+        elif self.when == 'M':
+            self.interval = 60 # one minute
+            self.suffix = "%Y-%m-%d_%H-%M"
+            self.extMatch = r"^\d{4}-\d{2}-\d{2}_\d{2}-\d{2}(\.\w+)?$"
+        elif self.when == 'H':
+            self.interval = 60 * 60 # one hour
+            self.suffix = "%Y-%m-%d_%H"
+            self.extMatch = r"^\d{4}-\d{2}-\d{2}_\d{2}(\.\w+)?$"
+        elif self.when == 'D' or self.when == 'MIDNIGHT':
+            self.interval = 60 * 60 * 24 # one day
+            self.suffix = "%Y-%m-%d"
+            self.extMatch = r"^\d{4}-\d{2}-\d{2}(\.\w+)?$"
+        elif self.when.startswith('W'):
+            self.interval = 60 * 60 * 24 * 7 # one week
+            if len(self.when) != 2:
+                raise ValueError("You must specify a day for weekly rollover from 0 to 6 (0 is Monday): %s" % self.when)
+            if self.when[1] < '0' or self.when[1] > '6':
+                raise ValueError("Invalid day specified for weekly rollover: %s" % self.when)
+            self.dayOfWeek = int(self.when[1])
+            self.suffix = "%Y-%m-%d"
+            self.extMatch = r"^\d{4}-\d{2}-\d{2}(\.\w+)?$"
+        else:
+            raise ValueError("Invalid rollover interval specified: %s" % self.when)
+
+        self.extMatch = re.compile(self.extMatch, re.ASCII)
+        self.interval = self.interval * interval # multiply by units requested
+        # The following line added because the filename passed in could be a
+        # path object (see Issue #27493), but self.baseFilename will be a string
+        filename = self.baseFilename
+        if os.path.exists(filename):
+            t = os.stat(filename)[ST_MTIME]
+        else:
+            t = int(time.time())
+        self.rolloverAt = self.computeRollover(t)
+
+    def computeRollover(self, currentTime):
+        """
+        Work out the rollover time based on the specified time.
+        """
+        result = currentTime + self.interval
+        # If we are rolling over at midnight or weekly, then the interval is already known.
+        # What we need to figure out is WHEN the next interval is.  In other words,
+        # if you are rolling over at midnight, then your base interval is 1 day,
+        # but you want to start that one day clock at midnight, not now.  So, we
+        # have to fudge the rolloverAt value in order to trigger the first rollover
+        # at the right time.  After that, the regular interval will take care of
+        # the rest.  Note that this code doesn't care about leap seconds. :)
+        if self.when == 'MIDNIGHT' or self.when.startswith('W'):
+            # This could be done with less code, but I wanted it to be clear
+            if self.utc:
+                t = time.gmtime(currentTime)
+            else:
+                t = time.localtime(currentTime)
+            currentHour = t[3]
+            currentMinute = t[4]
+            currentSecond = t[5]
+            currentDay = t[6]
+            # r is the number of seconds left between now and the next rotation
+            if self.atTime is None:
+                rotate_ts = _MIDNIGHT
+            else:
+                rotate_ts = ((self.atTime.hour * 60 + self.atTime.minute)*60 +
+                    self.atTime.second)
+
+            r = rotate_ts - ((currentHour * 60 + currentMinute) * 60 +
+                currentSecond)
+            if r < 0:
+                # Rotate time is before the current time (for example when
+                # self.rotateAt is 13:45 and it now 14:15), rotation is
+                # tomorrow.
+                r += _MIDNIGHT
+                currentDay = (currentDay + 1) % 7
+            result = currentTime + r
+            # If we are rolling over on a certain day, add in the number of days until
+            # the next rollover, but offset by 1 since we just calculated the time
+            # until the next day starts.  There are three cases:
+            # Case 1) The day to rollover is today; in this case, do nothing
+            # Case 2) The day to rollover is further in the interval (i.e., today is
+            #         day 2 (Wednesday) and rollover is on day 6 (Sunday).  Days to
+            #         next rollover is simply 6 - 2 - 1, or 3.
+            # Case 3) The day to rollover is behind us in the interval (i.e., today
+            #         is day 5 (Saturday) and rollover is on day 3 (Thursday).
+            #         Days to rollover is 6 - 5 + 3, or 4.  In this case, it's the
+            #         number of days left in the current week (1) plus the number
+            #         of days in the next week until the rollover day (3).
+            # The calculations described in 2) and 3) above need to have a day added.
+            # This is because the above time calculation takes us to midnight on this
+            # day, i.e. the start of the next day.
+            if self.when.startswith('W'):
+                day = currentDay # 0 is Monday
+                if day != self.dayOfWeek:
+                    if day < self.dayOfWeek:
+                        daysToWait = self.dayOfWeek - day
+                    else:
+                        daysToWait = 6 - day + self.dayOfWeek + 1
+                    newRolloverAt = result + (daysToWait * (60 * 60 * 24))
+                    if not self.utc:
+                        dstNow = t[-1]
+                        dstAtRollover = time.localtime(newRolloverAt)[-1]
+                        if dstNow != dstAtRollover:
+                            if not dstNow:  # DST kicks in before next rollover, so we need to deduct an hour
+                                addend = -3600
+                            else:           # DST bows out before next rollover, so we need to add an hour
+                                addend = 3600
+                            newRolloverAt += addend
+                    result = newRolloverAt
+        return result
+
+    def shouldRollover(self, record):
+        """
+        Determine if rollover should occur.
+
+        record is not used, as we are just comparing times, but it is needed so
+        the method signatures are the same
+        """
+        t = int(time.time())
+        if t >= self.rolloverAt:
+            # See #89564: Never rollover anything other than regular files
+            if os.path.exists(self.baseFilename) and not os.path.isfile(self.baseFilename):
+                # The file is not a regular file, so do not rollover, but do
+                # set the next rollover time to avoid repeated checks.
+                self.rolloverAt = self.computeRollover(t)
+                return False
+
+            return True
+        return False
+
+    def getFilesToDelete(self):
+        """
+        Determine the files to delete when rolling over.
+
+        More specific than the earlier method, which just used glob.glob().
+        """
+        dirName, baseName = os.path.split(self.baseFilename)
+        fileNames = os.listdir(dirName)
+        result = []
+        # See bpo-44753: Don't use the extension when computing the prefix.
+        n, e = os.path.splitext(baseName)
+        prefix = n + '.'
+        plen = len(prefix)
+        for fileName in fileNames:
+            if self.namer is None:
+                # Our files will always start with baseName
+                if not fileName.startswith(baseName):
+                    continue
+            else:
+                # Our files could be just about anything after custom naming, but
+                # likely candidates are of the form
+                # foo.log.DATETIME_SUFFIX or foo.DATETIME_SUFFIX.log
+                if (not fileName.startswith(baseName) and fileName.endswith(e) and
+                    len(fileName) > (plen + 1) and not fileName[plen+1].isdigit()):
+                    continue
+
+            if fileName[:plen] == prefix:
+                suffix = fileName[plen:]
+                # See bpo-45628: The date/time suffix could be anywhere in the
+                # filename
+                parts = suffix.split('.')
+                for part in parts:
+                    if self.extMatch.match(part):
+                        result.append(os.path.join(dirName, fileName))
+                        break
+        if len(result) < self.backupCount:
+            result = []
+        else:
+            result.sort()
+            result = result[:len(result) - self.backupCount]
+        return result
+
+    def doRollover(self):
+        """
+        do a rollover; in this case, a date/time stamp is appended to the filename
+        when the rollover happens.  However, you want the file to be named for the
+        start of the interval, not the current time.  If there is a backup count,
+        then we have to get a list of matching filenames, sort them and remove
+        the one with the oldest suffix.
+        """
+        if self.stream:
+            self.stream.close()
+            self.stream = None
+        # get the time that this sequence started at and make it a TimeTuple
+        currentTime = int(time.time())
+        dstNow = time.localtime(currentTime)[-1]
+        t = self.rolloverAt - self.interval
+        if self.utc:
+            timeTuple = time.gmtime(t)
+        else:
+            timeTuple = time.localtime(t)
+            dstThen = timeTuple[-1]
+            if dstNow != dstThen:
+                if dstNow:
+                    addend = 3600
+                else:
+                    addend = -3600
+                timeTuple = time.localtime(t + addend)
+        dfn = self.rotation_filename(self.baseFilename + "." +
+                                     time.strftime(self.suffix, timeTuple))
+        if os.path.exists(dfn):
+            os.remove(dfn)
+        self.rotate(self.baseFilename, dfn)
+        if self.backupCount > 0:
+            for s in self.getFilesToDelete():
+                os.remove(s)
+        if not self.delay:
+            self.stream = self._open()
+        newRolloverAt = self.computeRollover(currentTime)
+        while newRolloverAt <= currentTime:
+            newRolloverAt = newRolloverAt + self.interval
+        #If DST changes and midnight or weekly rollover, adjust for this.
+        if (self.when == 'MIDNIGHT' or self.when.startswith('W')) and not self.utc:
+            dstAtRollover = time.localtime(newRolloverAt)[-1]
+            if dstNow != dstAtRollover:
+                if not dstNow:  # DST kicks in before next rollover, so we need to deduct an hour
+                    addend = -3600
+                else:           # DST bows out before next rollover, so we need to add an hour
+                    addend = 3600
+                newRolloverAt += addend
+        self.rolloverAt = newRolloverAt
+
+class WatchedFileHandler(logging.FileHandler):
+    """
+    A handler for logging to a file, which watches the file
+    to see if it has changed while in use. This can happen because of
+    usage of programs such as newsyslog and logrotate which perform
+    log file rotation. This handler, intended for use under Unix,
+    watches the file to see if it has changed since the last emit.
+    (A file has changed if its device or inode have changed.)
+    If it has changed, the old file stream is closed, and the file
+    opened to get a new stream.
+
+    This handler is not appropriate for use under Windows, because
+    under Windows open files cannot be moved or renamed - logging
+    opens the files with exclusive locks - and so there is no need
+    for such a handler. Furthermore, ST_INO is not supported under
+    Windows; stat always returns zero for this value.
+
+    This handler is based on a suggestion and patch by Chad J.
+    Schroeder.
+    """
+    def __init__(self, filename, mode='a', encoding=None, delay=False,
+                 errors=None):
+        if "b" not in mode:
+            encoding = io.text_encoding(encoding)
+        logging.FileHandler.__init__(self, filename, mode=mode,
+                                     encoding=encoding, delay=delay,
+                                     errors=errors)
+        self.dev, self.ino = -1, -1
+        self._statstream()
+
+    def _statstream(self):
+        if self.stream:
+            sres = os.fstat(self.stream.fileno())
+            self.dev, self.ino = sres[ST_DEV], sres[ST_INO]
+
+    def reopenIfNeeded(self):
+        """
+        Reopen log file if needed.
+
+        Checks if the underlying file has changed, and if it
+        has, close the old stream and reopen the file to get the
+        current stream.
+        """
+        # Reduce the chance of race conditions by stat'ing by path only
+        # once and then fstat'ing our new fd if we opened a new log stream.
+        # See issue #14632: Thanks to John Mulligan for the problem report
+        # and patch.
+        try:
+            # stat the file by path, checking for existence
+            sres = os.stat(self.baseFilename)
+        except FileNotFoundError:
+            sres = None
+        # compare file system stat with that of our stream file handle
+        if not sres or sres[ST_DEV] != self.dev or sres[ST_INO] != self.ino:
+            if self.stream is not None:
+                # we have an open file handle, clean it up
+                self.stream.flush()
+                self.stream.close()
+                self.stream = None  # See Issue #21742: _open () might fail.
+                # open a new file handle and get new stat info from that fd
+                self.stream = self._open()
+                self._statstream()
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        If underlying file has changed, reopen the file before emitting the
+        record to it.
+        """
+        self.reopenIfNeeded()
+        logging.FileHandler.emit(self, record)
+
+
+class SocketHandler(logging.Handler):
+    """
+    A handler class which writes logging records, in pickle format, to
+    a streaming socket. The socket is kept open across logging calls.
+    If the peer resets it, an attempt is made to reconnect on the next call.
+    The pickle which is sent is that of the LogRecord's attribute dictionary
+    (__dict__), so that the receiver does not need to have the logging module
+    installed in order to process the logging event.
+
+    To unpickle the record at the receiving end into a LogRecord, use the
+    makeLogRecord function.
+    """
+
+    def __init__(self, host, port):
+        """
+        Initializes the handler with a specific host address and port.
+
+        When the attribute *closeOnError* is set to True - if a socket error
+        occurs, the socket is silently closed and then reopened on the next
+        logging call.
+        """
+        logging.Handler.__init__(self)
+        self.host = host
+        self.port = port
+        if port is None:
+            self.address = host
+        else:
+            self.address = (host, port)
+        self.sock = None
+        self.closeOnError = False
+        self.retryTime = None
+        #
+        # Exponential backoff parameters.
+        #
+        self.retryStart = 1.0
+        self.retryMax = 30.0
+        self.retryFactor = 2.0
+
+    def makeSocket(self, timeout=1):
+        """
+        A factory method which allows subclasses to define the precise
+        type of socket they want.
+        """
+        if self.port is not None:
+            result = socket.create_connection(self.address, timeout=timeout)
+        else:
+            result = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+            result.settimeout(timeout)
+            try:
+                result.connect(self.address)
+            except OSError:
+                result.close()  # Issue 19182
+                raise
+        return result
+
+    def createSocket(self):
+        """
+        Try to create a socket, using an exponential backoff with
+        a max retry time. Thanks to Robert Olson for the original patch
+        (SF #815911) which has been slightly refactored.
+        """
+        now = time.time()
+        # Either retryTime is None, in which case this
+        # is the first time back after a disconnect, or
+        # we've waited long enough.
+        if self.retryTime is None:
+            attempt = True
+        else:
+            attempt = (now >= self.retryTime)
+        if attempt:
+            try:
+                self.sock = self.makeSocket()
+                self.retryTime = None # next time, no delay before trying
+            except OSError:
+                #Creation failed, so set the retry time and return.
+                if self.retryTime is None:
+                    self.retryPeriod = self.retryStart
+                else:
+                    self.retryPeriod = self.retryPeriod * self.retryFactor
+                    if self.retryPeriod > self.retryMax:
+                        self.retryPeriod = self.retryMax
+                self.retryTime = now + self.retryPeriod
+
+    def send(self, s):
+        """
+        Send a pickled string to the socket.
+
+        This function allows for partial sends which can happen when the
+        network is busy.
+        """
+        if self.sock is None:
+            self.createSocket()
+        #self.sock can be None either because we haven't reached the retry
+        #time yet, or because we have reached the retry time and retried,
+        #but are still unable to connect.
+        if self.sock:
+            try:
+                self.sock.sendall(s)
+            except OSError: #pragma: no cover
+                self.sock.close()
+                self.sock = None  # so we can call createSocket next time
+
+    def makePickle(self, record):
+        """
+        Pickles the record in binary format with a length prefix, and
+        returns it ready for transmission across the socket.
+        """
+        ei = record.exc_info
+        if ei:
+            # just to get traceback text into record.exc_text ...
+            dummy = self.format(record)
+        # See issue #14436: If msg or args are objects, they may not be
+        # available on the receiving end. So we convert the msg % args
+        # to a string, save it as msg and zap the args.
+        d = dict(record.__dict__)
+        d['msg'] = record.getMessage()
+        d['args'] = None
+        d['exc_info'] = None
+        # Issue #25685: delete 'message' if present: redundant with 'msg'
+        d.pop('message', None)
+        s = pickle.dumps(d, 1)
+        slen = struct.pack(">L", len(s))
+        return slen + s
+
+    def handleError(self, record):
+        """
+        Handle an error during logging.
+
+        An error has occurred during logging. Most likely cause -
+        connection lost. Close the socket so that we can retry on the
+        next event.
+        """
+        if self.closeOnError and self.sock:
+            self.sock.close()
+            self.sock = None        #try to reconnect next time
+        else:
+            logging.Handler.handleError(self, record)
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        Pickles the record and writes it to the socket in binary format.
+        If there is an error with the socket, silently drop the packet.
+        If there was a problem with the socket, re-establishes the
+        socket.
+        """
+        try:
+            s = self.makePickle(record)
+            self.send(s)
+        except Exception:
+            self.handleError(record)
+
+    def close(self):
+        """
+        Closes the socket.
+        """
+        self.acquire()
+        try:
+            sock = self.sock
+            if sock:
+                self.sock = None
+                sock.close()
+            logging.Handler.close(self)
+        finally:
+            self.release()
+
+class DatagramHandler(SocketHandler):
+    """
+    A handler class which writes logging records, in pickle format, to
+    a datagram socket.  The pickle which is sent is that of the LogRecord's
+    attribute dictionary (__dict__), so that the receiver does not need to
+    have the logging module installed in order to process the logging event.
+
+    To unpickle the record at the receiving end into a LogRecord, use the
+    makeLogRecord function.
+
+    """
+    def __init__(self, host, port):
+        """
+        Initializes the handler with a specific host address and port.
+        """
+        SocketHandler.__init__(self, host, port)
+        self.closeOnError = False
+
+    def makeSocket(self):
+        """
+        The factory method of SocketHandler is here overridden to create
+        a UDP socket (SOCK_DGRAM).
+        """
+        if self.port is None:
+            family = socket.AF_UNIX
+        else:
+            family = socket.AF_INET
+        s = socket.socket(family, socket.SOCK_DGRAM)
+        return s
+
+    def send(self, s):
+        """
+        Send a pickled string to a socket.
+
+        This function no longer allows for partial sends which can happen
+        when the network is busy - UDP does not guarantee delivery and
+        can deliver packets out of sequence.
+        """
+        if self.sock is None:
+            self.createSocket()
+        self.sock.sendto(s, self.address)
+
+class SysLogHandler(logging.Handler):
+    """
+    A handler class which sends formatted logging records to a syslog
+    server. Based on Sam Rushing's syslog module:
+    http://www.nightmare.com/squirl/python-ext/misc/syslog.py
+    Contributed by Nicolas Untz (after which minor refactoring changes
+    have been made).
+    """
+
+    # from <linux/sys/syslog.h>:
+    # ======================================================================
+    # priorities/facilities are encoded into a single 32-bit quantity, where
+    # the bottom 3 bits are the priority (0-7) and the top 28 bits are the
+    # facility (0-big number). Both the priorities and the facilities map
+    # roughly one-to-one to strings in the syslogd(8) source code.  This
+    # mapping is included in this file.
+    #
+    # priorities (these are ordered)
+
+    LOG_EMERG     = 0       #  system is unusable
+    LOG_ALERT     = 1       #  action must be taken immediately
+    LOG_CRIT      = 2       #  critical conditions
+    LOG_ERR       = 3       #  error conditions
+    LOG_WARNING   = 4       #  warning conditions
+    LOG_NOTICE    = 5       #  normal but significant condition
+    LOG_INFO      = 6       #  informational
+    LOG_DEBUG     = 7       #  debug-level messages
+
+    #  facility codes
+    LOG_KERN      = 0       #  kernel messages
+    LOG_USER      = 1       #  random user-level messages
+    LOG_MAIL      = 2       #  mail system
+    LOG_DAEMON    = 3       #  system daemons
+    LOG_AUTH      = 4       #  security/authorization messages
+    LOG_SYSLOG    = 5       #  messages generated internally by syslogd
+    LOG_LPR       = 6       #  line printer subsystem
+    LOG_NEWS      = 7       #  network news subsystem
+    LOG_UUCP      = 8       #  UUCP subsystem
+    LOG_CRON      = 9       #  clock daemon
+    LOG_AUTHPRIV  = 10      #  security/authorization messages (private)
+    LOG_FTP       = 11      #  FTP daemon
+    LOG_NTP       = 12      #  NTP subsystem
+    LOG_SECURITY  = 13      #  Log audit
+    LOG_CONSOLE   = 14      #  Log alert
+    LOG_SOLCRON   = 15      #  Scheduling daemon (Solaris)
+
+    #  other codes through 15 reserved for system use
+    LOG_LOCAL0    = 16      #  reserved for local use
+    LOG_LOCAL1    = 17      #  reserved for local use
+    LOG_LOCAL2    = 18      #  reserved for local use
+    LOG_LOCAL3    = 19      #  reserved for local use
+    LOG_LOCAL4    = 20      #  reserved for local use
+    LOG_LOCAL5    = 21      #  reserved for local use
+    LOG_LOCAL6    = 22      #  reserved for local use
+    LOG_LOCAL7    = 23      #  reserved for local use
+
+    priority_names = {
+        "alert":    LOG_ALERT,
+        "crit":     LOG_CRIT,
+        "critical": LOG_CRIT,
+        "debug":    LOG_DEBUG,
+        "emerg":    LOG_EMERG,
+        "err":      LOG_ERR,
+        "error":    LOG_ERR,        #  DEPRECATED
+        "info":     LOG_INFO,
+        "notice":   LOG_NOTICE,
+        "panic":    LOG_EMERG,      #  DEPRECATED
+        "warn":     LOG_WARNING,    #  DEPRECATED
+        "warning":  LOG_WARNING,
+        }
+
+    facility_names = {
+        "auth":         LOG_AUTH,
+        "authpriv":     LOG_AUTHPRIV,
+        "console":      LOG_CONSOLE,
+        "cron":         LOG_CRON,
+        "daemon":       LOG_DAEMON,
+        "ftp":          LOG_FTP,
+        "kern":         LOG_KERN,
+        "lpr":          LOG_LPR,
+        "mail":         LOG_MAIL,
+        "news":         LOG_NEWS,
+        "ntp":          LOG_NTP,
+        "security":     LOG_SECURITY,
+        "solaris-cron": LOG_SOLCRON,
+        "syslog":       LOG_SYSLOG,
+        "user":         LOG_USER,
+        "uucp":         LOG_UUCP,
+        "local0":       LOG_LOCAL0,
+        "local1":       LOG_LOCAL1,
+        "local2":       LOG_LOCAL2,
+        "local3":       LOG_LOCAL3,
+        "local4":       LOG_LOCAL4,
+        "local5":       LOG_LOCAL5,
+        "local6":       LOG_LOCAL6,
+        "local7":       LOG_LOCAL7,
+        }
+
+    # Originally added to work around GH-43683. Unnecessary since GH-50043 but kept
+    # for backwards compatibility.
+    priority_map = {
+        "DEBUG" : "debug",
+        "INFO" : "info",
+        "WARNING" : "warning",
+        "ERROR" : "error",
+        "CRITICAL" : "critical"
+    }
+
+    def __init__(self, address=('localhost', SYSLOG_UDP_PORT),
+                 facility=LOG_USER, socktype=None):
+        """
+        Initialize a handler.
+
+        If address is specified as a string, a UNIX socket is used. To log to a
+        local syslogd, "SysLogHandler(address="/dev/log")" can be used.
+        If facility is not specified, LOG_USER is used. If socktype is
+        specified as socket.SOCK_DGRAM or socket.SOCK_STREAM, that specific
+        socket type will be used. For Unix sockets, you can also specify a
+        socktype of None, in which case socket.SOCK_DGRAM will be used, falling
+        back to socket.SOCK_STREAM.
+        """
+        logging.Handler.__init__(self)
+
+        self.address = address
+        self.facility = facility
+        self.socktype = socktype
+        self.socket = None
+        self.createSocket()
+
+    def _connect_unixsocket(self, address):
+        use_socktype = self.socktype
+        if use_socktype is None:
+            use_socktype = socket.SOCK_DGRAM
+        self.socket = socket.socket(socket.AF_UNIX, use_socktype)
+        try:
+            self.socket.connect(address)
+            # it worked, so set self.socktype to the used type
+            self.socktype = use_socktype
+        except OSError:
+            self.socket.close()
+            if self.socktype is not None:
+                # user didn't specify falling back, so fail
+                raise
+            use_socktype = socket.SOCK_STREAM
+            self.socket = socket.socket(socket.AF_UNIX, use_socktype)
+            try:
+                self.socket.connect(address)
+                # it worked, so set self.socktype to the used type
+                self.socktype = use_socktype
+            except OSError:
+                self.socket.close()
+                raise
+
+    def createSocket(self):
+        """
+        Try to create a socket and, if it's not a datagram socket, connect it
+        to the other end. This method is called during handler initialization,
+        but it's not regarded as an error if the other end isn't listening yet
+        --- the method will be called again when emitting an event,
+        if there is no socket at that point.
+        """
+        address = self.address
+        socktype = self.socktype
+
+        if isinstance(address, str):
+            self.unixsocket = True
+            # Syslog server may be unavailable during handler initialisation.
+            # C's openlog() function also ignores connection errors.
+            # Moreover, we ignore these errors while logging, so it's not worse
+            # to ignore it also here.
+            try:
+                self._connect_unixsocket(address)
+            except OSError:
+                pass
+        else:
+            self.unixsocket = False
+            if socktype is None:
+                socktype = socket.SOCK_DGRAM
+            host, port = address
+            ress = socket.getaddrinfo(host, port, 0, socktype)
+            if not ress:
+                raise OSError("getaddrinfo returns an empty list")
+            for res in ress:
+                af, socktype, proto, _, sa = res
+                err = sock = None
+                try:
+                    sock = socket.socket(af, socktype, proto)
+                    if socktype == socket.SOCK_STREAM:
+                        sock.connect(sa)
+                    break
+                except OSError as exc:
+                    err = exc
+                    if sock is not None:
+                        sock.close()
+            if err is not None:
+                raise err
+            self.socket = sock
+            self.socktype = socktype
+
+    def encodePriority(self, facility, priority):
+        """
+        Encode the facility and priority. You can pass in strings or
+        integers - if strings are passed, the facility_names and
+        priority_names mapping dictionaries are used to convert them to
+        integers.
+        """
+        if isinstance(facility, str):
+            facility = self.facility_names[facility]
+        if isinstance(priority, str):
+            priority = self.priority_names[priority]
+        return (facility << 3) | priority
+
+    def close(self):
+        """
+        Closes the socket.
+        """
+        self.acquire()
+        try:
+            sock = self.socket
+            if sock:
+                self.socket = None
+                sock.close()
+            logging.Handler.close(self)
+        finally:
+            self.release()
+
+    def mapPriority(self, levelName):
+        """
+        Map a logging level name to a key in the priority_names map.
+        This is useful in two scenarios: when custom levels are being
+        used, and in the case where you can't do a straightforward
+        mapping by lowercasing the logging level name because of locale-
+        specific issues (see SF #1524081).
+        """
+        return self.priority_map.get(levelName, "warning")
+
+    ident = ''          # prepended to all messages
+    append_nul = True   # some old syslog daemons expect a NUL terminator
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        The record is formatted, and then sent to the syslog server. If
+        exception information is present, it is NOT sent to the server.
+        """
+        try:
+            msg = self.format(record)
+            if self.ident:
+                msg = self.ident + msg
+            if self.append_nul:
+                msg += '\000'
+
+            # We need to convert record level to lowercase, maybe this will
+            # change in the future.
+            prio = '<%d>' % self.encodePriority(self.facility,
+                                                self.mapPriority(record.levelname))
+            prio = prio.encode('utf-8')
+            # Message is a string. Convert to bytes as required by RFC 5424
+            msg = msg.encode('utf-8')
+            msg = prio + msg
+
+            if not self.socket:
+                self.createSocket()
+
+            if self.unixsocket:
+                try:
+                    self.socket.send(msg)
+                except OSError:
+                    self.socket.close()
+                    self._connect_unixsocket(self.address)
+                    self.socket.send(msg)
+            elif self.socktype == socket.SOCK_DGRAM:
+                self.socket.sendto(msg, self.address)
+            else:
+                self.socket.sendall(msg)
+        except Exception:
+            self.handleError(record)
+
+class SMTPHandler(logging.Handler):
+    """
+    A handler class which sends an SMTP email for each logging event.
+    """
+    def __init__(self, mailhost, fromaddr, toaddrs, subject,
+                 credentials=None, secure=None, timeout=5.0):
+        """
+        Initialize the handler.
+
+        Initialize the instance with the from and to addresses and subject
+        line of the email. To specify a non-standard SMTP port, use the
+        (host, port) tuple format for the mailhost argument. To specify
+        authentication credentials, supply a (username, password) tuple
+        for the credentials argument. To specify the use of a secure
+        protocol (TLS), pass in a tuple for the secure argument. This will
+        only be used when authentication credentials are supplied. The tuple
+        will be either an empty tuple, or a single-value tuple with the name
+        of a keyfile, or a 2-value tuple with the names of the keyfile and
+        certificate file. (This tuple is passed to the `starttls` method).
+        A timeout in seconds can be specified for the SMTP connection (the
+        default is one second).
+        """
+        logging.Handler.__init__(self)
+        if isinstance(mailhost, (list, tuple)):
+            self.mailhost, self.mailport = mailhost
+        else:
+            self.mailhost, self.mailport = mailhost, None
+        if isinstance(credentials, (list, tuple)):
+            self.username, self.password = credentials
+        else:
+            self.username = None
+        self.fromaddr = fromaddr
+        if isinstance(toaddrs, str):
+            toaddrs = [toaddrs]
+        self.toaddrs = toaddrs
+        self.subject = subject
+        self.secure = secure
+        self.timeout = timeout
+
+    def getSubject(self, record):
+        """
+        Determine the subject for the email.
+
+        If you want to specify a subject line which is record-dependent,
+        override this method.
+        """
+        return self.subject
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        Format the record and send it to the specified addressees.
+        """
+        try:
+            import smtplib
+            from email.message import EmailMessage
+            import email.utils
+
+            port = self.mailport
+            if not port:
+                port = smtplib.SMTP_PORT
+            smtp = smtplib.SMTP(self.mailhost, port, timeout=self.timeout)
+            msg = EmailMessage()
+            msg['From'] = self.fromaddr
+            msg['To'] = ','.join(self.toaddrs)
+            msg['Subject'] = self.getSubject(record)
+            msg['Date'] = email.utils.localtime()
+            msg.set_content(self.format(record))
+            if self.username:
+                if self.secure is not None:
+                    smtp.ehlo()
+                    smtp.starttls(*self.secure)
+                    smtp.ehlo()
+                smtp.login(self.username, self.password)
+            smtp.send_message(msg)
+            smtp.quit()
+        except Exception:
+            self.handleError(record)
+
+class NTEventLogHandler(logging.Handler):
+    """
+    A handler class which sends events to the NT Event Log. Adds a
+    registry entry for the specified application name. If no dllname is
+    provided, win32service.pyd (which contains some basic message
+    placeholders) is used. Note that use of these placeholders will make
+    your event logs big, as the entire message source is held in the log.
+    If you want slimmer logs, you have to pass in the name of your own DLL
+    which contains the message definitions you want to use in the event log.
+    """
+    def __init__(self, appname, dllname=None, logtype="Application"):
+        logging.Handler.__init__(self)
+        try:
+            import win32evtlogutil, win32evtlog
+            self.appname = appname
+            self._welu = win32evtlogutil
+            if not dllname:
+                dllname = os.path.split(self._welu.__file__)
+                dllname = os.path.split(dllname[0])
+                dllname = os.path.join(dllname[0], r'win32service.pyd')
+            self.dllname = dllname
+            self.logtype = logtype
+            # Administrative privileges are required to add a source to the registry.
+            # This may not be available for a user that just wants to add to an
+            # existing source - handle this specific case.
+            try:
+                self._welu.AddSourceToRegistry(appname, dllname, logtype)
+            except Exception as e:
+                # This will probably be a pywintypes.error. Only raise if it's not
+                # an "access denied" error, else let it pass
+                if getattr(e, 'winerror', None) != 5:  # not access denied
+                    raise
+            self.deftype = win32evtlog.EVENTLOG_ERROR_TYPE
+            self.typemap = {
+                logging.DEBUG   : win32evtlog.EVENTLOG_INFORMATION_TYPE,
+                logging.INFO    : win32evtlog.EVENTLOG_INFORMATION_TYPE,
+                logging.WARNING : win32evtlog.EVENTLOG_WARNING_TYPE,
+                logging.ERROR   : win32evtlog.EVENTLOG_ERROR_TYPE,
+                logging.CRITICAL: win32evtlog.EVENTLOG_ERROR_TYPE,
+         }
+        except ImportError:
+            print("The Python Win32 extensions for NT (service, event "\
+                        "logging) appear not to be available.")
+            self._welu = None
+
+    def getMessageID(self, record):
+        """
+        Return the message ID for the event record. If you are using your
+        own messages, you could do this by having the msg passed to the
+        logger being an ID rather than a formatting string. Then, in here,
+        you could use a dictionary lookup to get the message ID. This
+        version returns 1, which is the base message ID in win32service.pyd.
+        """
+        return 1
+
+    def getEventCategory(self, record):
+        """
+        Return the event category for the record.
+
+        Override this if you want to specify your own categories. This version
+        returns 0.
+        """
+        return 0
+
+    def getEventType(self, record):
+        """
+        Return the event type for the record.
+
+        Override this if you want to specify your own types. This version does
+        a mapping using the handler's typemap attribute, which is set up in
+        __init__() to a dictionary which contains mappings for DEBUG, INFO,
+        WARNING, ERROR and CRITICAL. If you are using your own levels you will
+        either need to override this method or place a suitable dictionary in
+        the handler's typemap attribute.
+        """
+        return self.typemap.get(record.levelno, self.deftype)
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        Determine the message ID, event category and event type. Then
+        log the message in the NT event log.
+        """
+        if self._welu:
+            try:
+                id = self.getMessageID(record)
+                cat = self.getEventCategory(record)
+                type = self.getEventType(record)
+                msg = self.format(record)
+                self._welu.ReportEvent(self.appname, id, cat, type, [msg])
+            except Exception:
+                self.handleError(record)
+
+    def close(self):
+        """
+        Clean up this handler.
+
+        You can remove the application name from the registry as a
+        source of event log entries. However, if you do this, you will
+        not be able to see the events as you intended in the Event Log
+        Viewer - it needs to be able to access the registry to get the
+        DLL name.
+        """
+        #self._welu.RemoveSourceFromRegistry(self.appname, self.logtype)
+        logging.Handler.close(self)
+
+class HTTPHandler(logging.Handler):
+    """
+    A class which sends records to a web server, using either GET or
+    POST semantics.
+    """
+    def __init__(self, host, url, method="GET", secure=False, credentials=None,
+                 context=None):
+        """
+        Initialize the instance with the host, the request URL, and the method
+        ("GET" or "POST")
+        """
+        logging.Handler.__init__(self)
+        method = method.upper()
+        if method not in ["GET", "POST"]:
+            raise ValueError("method must be GET or POST")
+        if not secure and context is not None:
+            raise ValueError("context parameter only makes sense "
+                             "with secure=True")
+        self.host = host
+        self.url = url
+        self.method = method
+        self.secure = secure
+        self.credentials = credentials
+        self.context = context
+
+    def mapLogRecord(self, record):
+        """
+        Default implementation of mapping the log record into a dict
+        that is sent as the CGI data. Overwrite in your class.
+        Contributed by Franz Glasner.
+        """
+        return record.__dict__
+
+    def getConnection(self, host, secure):
+        """
+        get a HTTP[S]Connection.
+
+        Override when a custom connection is required, for example if
+        there is a proxy.
+        """
+        import http.client
+        if secure:
+            connection = http.client.HTTPSConnection(host, context=self.context)
+        else:
+            connection = http.client.HTTPConnection(host)
+        return connection
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        Send the record to the web server as a percent-encoded dictionary
+        """
+        try:
+            import urllib.parse
+            host = self.host
+            h = self.getConnection(host, self.secure)
+            url = self.url
+            data = urllib.parse.urlencode(self.mapLogRecord(record))
+            if self.method == "GET":
+                if (url.find('?') >= 0):
+                    sep = '&'
+                else:
+                    sep = '?'
+                url = url + "%c%s" % (sep, data)
+            h.putrequest(self.method, url)
+            # support multiple hosts on one IP address...
+            # need to strip optional :port from host, if present
+            i = host.find(":")
+            if i >= 0:
+                host = host[:i]
+            # See issue #30904: putrequest call above already adds this header
+            # on Python 3.x.
+            # h.putheader("Host", host)
+            if self.method == "POST":
+                h.putheader("Content-type",
+                            "application/x-www-form-urlencoded")
+                h.putheader("Content-length", str(len(data)))
+            if self.credentials:
+                import base64
+                s = ('%s:%s' % self.credentials).encode('utf-8')
+                s = 'Basic ' + base64.b64encode(s).strip().decode('ascii')
+                h.putheader('Authorization', s)
+            h.endheaders()
+            if self.method == "POST":
+                h.send(data.encode('utf-8'))
+            h.getresponse()    #can't do anything with the result
+        except Exception:
+            self.handleError(record)
+
+class BufferingHandler(logging.Handler):
+    """
+  A handler class which buffers logging records in memory. Whenever each
+  record is added to the buffer, a check is made to see if the buffer should
+  be flushed. If it should, then flush() is expected to do what's needed.
+    """
+    def __init__(self, capacity):
+        """
+        Initialize the handler with the buffer size.
+        """
+        logging.Handler.__init__(self)
+        self.capacity = capacity
+        self.buffer = []
+
+    def shouldFlush(self, record):
+        """
+        Should the handler flush its buffer?
+
+        Returns true if the buffer is up to capacity. This method can be
+        overridden to implement custom flushing strategies.
+        """
+        return (len(self.buffer) >= self.capacity)
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        Append the record. If shouldFlush() tells us to, call flush() to process
+        the buffer.
+        """
+        self.buffer.append(record)
+        if self.shouldFlush(record):
+            self.flush()
+
+    def flush(self):
+        """
+        Override to implement custom flushing behaviour.
+
+        This version just zaps the buffer to empty.
+        """
+        self.acquire()
+        try:
+            self.buffer.clear()
+        finally:
+            self.release()
+
+    def close(self):
+        """
+        Close the handler.
+
+        This version just flushes and chains to the parent class' close().
+        """
+        try:
+            self.flush()
+        finally:
+            logging.Handler.close(self)
+
+class MemoryHandler(BufferingHandler):
+    """
+    A handler class which buffers logging records in memory, periodically
+    flushing them to a target handler. Flushing occurs whenever the buffer
+    is full, or when an event of a certain severity or greater is seen.
+    """
+    def __init__(self, capacity, flushLevel=logging.ERROR, target=None,
+                 flushOnClose=True):
+        """
+        Initialize the handler with the buffer size, the level at which
+        flushing should occur and an optional target.
+
+        Note that without a target being set either here or via setTarget(),
+        a MemoryHandler is no use to anyone!
+
+        The ``flushOnClose`` argument is ``True`` for backward compatibility
+        reasons - the old behaviour is that when the handler is closed, the
+        buffer is flushed, even if the flush level hasn't been exceeded nor the
+        capacity exceeded. To prevent this, set ``flushOnClose`` to ``False``.
+        """
+        BufferingHandler.__init__(self, capacity)
+        self.flushLevel = flushLevel
+        self.target = target
+        # See Issue #26559 for why this has been added
+        self.flushOnClose = flushOnClose
+
+    def shouldFlush(self, record):
+        """
+        Check for buffer full or a record at the flushLevel or higher.
+        """
+        return (len(self.buffer) >= self.capacity) or \
+                (record.levelno >= self.flushLevel)
+
+    def setTarget(self, target):
+        """
+        Set the target handler for this handler.
+        """
+        self.acquire()
+        try:
+            self.target = target
+        finally:
+            self.release()
+
+    def flush(self):
+        """
+        For a MemoryHandler, flushing means just sending the buffered
+        records to the target, if there is one. Override if you want
+        different behaviour.
+
+        The record buffer is only cleared if a target has been set.
+        """
+        self.acquire()
+        try:
+            if self.target:
+                for record in self.buffer:
+                    self.target.handle(record)
+                self.buffer.clear()
+        finally:
+            self.release()
+
+    def close(self):
+        """
+        Flush, if appropriately configured, set the target to None and lose the
+        buffer.
+        """
+        try:
+            if self.flushOnClose:
+                self.flush()
+        finally:
+            self.acquire()
+            try:
+                self.target = None
+                BufferingHandler.close(self)
+            finally:
+                self.release()
+
+
+class QueueHandler(logging.Handler):
+    """
+    This handler sends events to a queue. Typically, it would be used together
+    with a multiprocessing Queue to centralise logging to file in one process
+    (in a multi-process application), so as to avoid file write contention
+    between processes.
+
+    This code is new in Python 3.2, but this class can be copy pasted into
+    user code for use with earlier Python versions.
+    """
+
+    def __init__(self, queue):
+        """
+        Initialise an instance, using the passed queue.
+        """
+        logging.Handler.__init__(self)
+        self.queue = queue
+        self.listener = None  # will be set to listener if configured via dictConfig()
+
+    def enqueue(self, record):
+        """
+        Enqueue a record.
+
+        The base implementation uses put_nowait. You may want to override
+        this method if you want to use blocking, timeouts or custom queue
+        implementations.
+        """
+        self.queue.put_nowait(record)
+
+    def prepare(self, record):
+        """
+        Prepare a record for queuing. The object returned by this method is
+        enqueued.
+
+        The base implementation formats the record to merge the message and
+        arguments, and removes unpickleable items from the record in-place.
+        Specifically, it overwrites the record's `msg` and
+        `message` attributes with the merged message (obtained by
+        calling the handler's `format` method), and sets the `args`,
+        `exc_info` and `exc_text` attributes to None.
+
+        You might want to override this method if you want to convert
+        the record to a dict or JSON string, or send a modified copy
+        of the record while leaving the original intact.
+        """
+        # The format operation gets traceback text into record.exc_text
+        # (if there's exception data), and also returns the formatted
+        # message. We can then use this to replace the original
+        # msg + args, as these might be unpickleable. We also zap the
+        # exc_info, exc_text and stack_info attributes, as they are no longer
+        # needed and, if not None, will typically not be pickleable.
+        msg = self.format(record)
+        # bpo-35726: make copy of record to avoid affecting other handlers in the chain.
+        record = copy.copy(record)
+        record.message = msg
+        record.msg = msg
+        record.args = None
+        record.exc_info = None
+        record.exc_text = None
+        record.stack_info = None
+        return record
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        Writes the LogRecord to the queue, preparing it for pickling first.
+        """
+        try:
+            self.enqueue(self.prepare(record))
+        except Exception:
+            self.handleError(record)
+
+
+class QueueListener(object):
+    """
+    This class implements an internal threaded listener which watches for
+    LogRecords being added to a queue, removes them and passes them to a
+    list of handlers for processing.
+    """
+    _sentinel = None
+
+    def __init__(self, queue, *handlers, respect_handler_level=False):
+        """
+        Initialise an instance with the specified queue and
+        handlers.
+        """
+        self.queue = queue
+        self.handlers = handlers
+        self._thread = None
+        self.respect_handler_level = respect_handler_level
+
+    def dequeue(self, block):
+        """
+        Dequeue a record and return it, optionally blocking.
+
+        The base implementation uses get. You may want to override this method
+        if you want to use timeouts or work with custom queue implementations.
+        """
+        return self.queue.get(block)
+
+    def start(self):
+        """
+        Start the listener.
+
+        This starts up a background thread to monitor the queue for
+        LogRecords to process.
+        """
+        self._thread = t = threading.Thread(target=self._monitor)
+        t.daemon = True
+        t.start()
+
+    def prepare(self, record):
+        """
+        Prepare a record for handling.
+
+        This method just returns the passed-in record. You may want to
+        override this method if you need to do any custom marshalling or
+        manipulation of the record before passing it to the handlers.
+        """
+        return record
+
+    def handle(self, record):
+        """
+        Handle a record.
+
+        This just loops through the handlers offering them the record
+        to handle.
+        """
+        record = self.prepare(record)
+        for handler in self.handlers:
+            if not self.respect_handler_level:
+                process = True
+            else:
+                process = record.levelno >= handler.level
+            if process:
+                handler.handle(record)
+
+    def _monitor(self):
+        """
+        Monitor the queue for records, and ask the handler
+        to deal with them.
+
+        This method runs on a separate, internal thread.
+        The thread will terminate if it sees a sentinel object in the queue.
+        """
+        q = self.queue
+        has_task_done = hasattr(q, 'task_done')
+        while True:
+            try:
+                record = self.dequeue(True)
+                if record is self._sentinel:
+                    if has_task_done:
+                        q.task_done()
+                    break
+                self.handle(record)
+                if has_task_done:
+                    q.task_done()
+            except queue.Empty:
+                break
+
+    def enqueue_sentinel(self):
+        """
+        This is used to enqueue the sentinel record.
+
+        The base implementation uses put_nowait. You may want to override this
+        method if you want to use timeouts or work with custom queue
+        implementations.
+        """
+        self.queue.put_nowait(self._sentinel)
+
+    def stop(self):
+        """
+        Stop the listener.
+
+        This asks the thread to terminate, and then waits for it to do so.
+        Note that if you don't call this before your application exits, there
+        may be some records still left on the queue, which won't be processed.
+        """
+        self.enqueue_sentinel()
+        self._thread.join()
+        self._thread = None