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Editing File: /lib64/python3.8/logging/init.py

# Copyright 2001-2017 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.

"""
Logging package for Python. Based on PEP 282 and comments thereto in
comp.lang.python.

To use, simply 'import logging' and log away!
"""

import sys, os, time, io, re, traceback, warnings, weakref, collections.abc

from string import Template
from string import Formatter as StrFormatter

__all__ = ['BASIC_FORMAT', 'BufferingFormatter', 'CRITICAL', 'DEBUG', 'ERROR',
           'FATAL', 'FileHandler', 'Filter', 'Formatter', 'Handler', 'INFO',
           'LogRecord', 'Logger', 'LoggerAdapter', 'NOTSET', 'NullHandler',
           'StreamHandler', 'WARN', 'WARNING', 'addLevelName', 'basicConfig',
           'captureWarnings', 'critical', 'debug', 'disable', 'error',
           'exception', 'fatal', 'getLevelName', 'getLogger', 'getLoggerClass',
           'info', 'log', 'makeLogRecord', 'setLoggerClass', 'shutdown',
           'warn', 'warning', 'getLogRecordFactory', 'setLogRecordFactory',
           'lastResort', 'raiseExceptions']

import threading

__author__  = "Vinay Sajip <vinay_sajip@red-dove.com>"
__status__  = "production"
# The following module attributes are no longer updated.
__version__ = "0.5.1.2"
__date__    = "07 February 2010"

#---------------------------------------------------------------------------
#   Miscellaneous module data
#---------------------------------------------------------------------------

#
#_startTime is used as the base when calculating the relative time of events
#
_startTime = time.time()

#
#raiseExceptions is used to see if exceptions during handling should be
#propagated
#
raiseExceptions = True

#
# If you don't want threading information in the log, set this to zero
#
logThreads = True

#
# If you don't want multiprocessing information in the log, set this to zero
#
logMultiprocessing = True

#
# If you don't want process information in the log, set this to zero
#
logProcesses = True

#---------------------------------------------------------------------------
#   Level related stuff
#---------------------------------------------------------------------------
#
# Default levels and level names, these can be replaced with any positive set
# of values having corresponding names. There is a pseudo-level, NOTSET, which
# is only really there as a lower limit for user-defined levels. Handlers and
# loggers are initialized with NOTSET so that they will log all messages, even
# at user-defined levels.
#

CRITICAL = 50
FATAL = CRITICAL
ERROR = 40
WARNING = 30
WARN = WARNING
INFO = 20
DEBUG = 10
NOTSET = 0

_levelToName = {
    CRITICAL: 'CRITICAL',
    ERROR: 'ERROR',
    WARNING: 'WARNING',
    INFO: 'INFO',
    DEBUG: 'DEBUG',
    NOTSET: 'NOTSET',
}
_nameToLevel = {
    'CRITICAL': CRITICAL,
    'FATAL': FATAL,
    'ERROR': ERROR,
    'WARN': WARNING,
    'WARNING': WARNING,
    'INFO': INFO,
    'DEBUG': DEBUG,
    'NOTSET': NOTSET,
}

def getLevelName(level):
    """
    Return the textual or numeric representation of logging level 'level'.

If the level is one of the predefined levels (CRITICAL, ERROR, WARNING,
    INFO, DEBUG) then you get the corresponding string. If you have
    associated levels with names using addLevelName then the name you have
    associated with 'level' is returned.

If a numeric value corresponding to one of the defined levels is passed
    in, the corresponding string representation is returned.

If a string representation of the level is passed in, the corresponding
    numeric value is returned.

If no matching numeric or string value is passed in, the string
    'Level %s' % level is returned.
    """
    # See Issues #22386, #27937 and #29220 for why it's this way
    result = _levelToName.get(level)
    if result is not None:
        return result
    result = _nameToLevel.get(level)
    if result is not None:
        return result
    return "Level %s" % level

def addLevelName(level, levelName):
    """
    Associate 'levelName' with 'level'.

This is used when converting levels to text during message formatting.
    """
    _acquireLock()
    try:    #unlikely to cause an exception, but you never know...
        _levelToName[level] = levelName
        _nameToLevel[levelName] = level
    finally:
        _releaseLock()

if hasattr(sys, '_getframe'):
    currentframe = lambda: sys._getframe(3)
else: #pragma: no cover
    def currentframe():
        """Return the frame object for the caller's stack frame."""
        try:
            raise Exception
        except Exception:
            return sys.exc_info()[2].tb_frame.f_back

#
# _srcfile is used when walking the stack to check when we've got the first
# caller stack frame, by skipping frames whose filename is that of this
# module's source. It therefore should contain the filename of this module's
# source file.
#
# Ordinarily we would use __file__ for this, but frozen modules don't always
# have __file__ set, for some reason (see Issue #21736). Thus, we get the
# filename from a handy code object from a function defined in this module.
# (There's no particular reason for picking addLevelName.)
#

_srcfile = os.path.normcase(addLevelName.__code__.co_filename)

# _srcfile is only used in conjunction with sys._getframe().
# To provide compatibility with older versions of Python, set _srcfile
# to None if _getframe() is not available; this value will prevent
# findCaller() from being called. You can also do this if you want to avoid
# the overhead of fetching caller information, even when _getframe() is
# available.
#if not hasattr(sys, '_getframe'):
#    _srcfile = None

def _checkLevel(level):
    if isinstance(level, int):
        rv = level
    elif str(level) == level:
        if level not in _nameToLevel:
            raise ValueError("Unknown level: %r" % level)
        rv = _nameToLevel[level]
    else:
        raise TypeError("Level not an integer or a valid string: %r" % level)
    return rv

#---------------------------------------------------------------------------
#   Thread-related stuff
#---------------------------------------------------------------------------

#
#_lock is used to serialize access to shared data structures in this module.
#This needs to be an RLock because fileConfig() creates and configures
#Handlers, and so might arbitrary user threads. Since Handler code updates the
#shared dictionary _handlers, it needs to acquire the lock. But if configuring,
#the lock would already have been acquired - so we need an RLock.
#The same argument applies to Loggers and Manager.loggerDict.
#
_lock = threading.RLock()

def _acquireLock():
    """
    Acquire the module-level lock for serializing access to shared data.

This should be released with _releaseLock().
    """
    if _lock:
        _lock.acquire()

def _releaseLock():
    """
    Release the module-level lock acquired by calling _acquireLock().
    """
    if _lock:
        _lock.release()

# Prevent a held logging lock from blocking a child from logging.

if not hasattr(os, 'register_at_fork'):  # Windows and friends.
    def _register_at_fork_reinit_lock(instance):
        pass  # no-op when os.register_at_fork does not exist.
else:
    # A collection of instances with a createLock method (logging.Handler)
    # to be called in the child after forking.  The weakref avoids us keeping
    # discarded Handler instances alive.  A set is used to avoid accumulating
    # duplicate registrations as createLock() is responsible for registering
    # a new Handler instance with this set in the first place.
    _at_fork_reinit_lock_weakset = weakref.WeakSet()

def _register_at_fork_reinit_lock(instance):
        _acquireLock()
        try:
            _at_fork_reinit_lock_weakset.add(instance)
        finally:
            _releaseLock()

def _after_at_fork_child_reinit_locks():
        # _acquireLock() was called in the parent before forking.
        for handler in _at_fork_reinit_lock_weakset:
            try:
                handler.createLock()
            except Exception as err:
                # Similar to what PyErr_WriteUnraisable does.
                print("Ignoring exception from logging atfork", instance,
                      "._reinit_lock() method:", err, file=sys.stderr)
        _releaseLock()  # Acquired by os.register_at_fork(before=.

os.register_at_fork(before=_acquireLock,
                        after_in_child=_after_at_fork_child_reinit_locks,
                        after_in_parent=_releaseLock)

#---------------------------------------------------------------------------
#   The logging record
#---------------------------------------------------------------------------

class LogRecord(object):
    """
    A LogRecord instance represents an event being logged.

LogRecord instances are created every time something is logged. They
    contain all the information pertinent to the event being logged. The
    main information passed in is in msg and args, which are combined
    using str(msg) % args to create the message field of the record. The
    record also includes information such as when the record was created,
    the source line where the logging call was made, and any exception
    information to be logged.
    """
    def __init__(self, name, level, pathname, lineno,
                 msg, args, exc_info, func=None, sinfo=None, **kwargs):
        """
        Initialize a logging record with interesting information.
        """
        ct = time.time()
        self.name = name
        self.msg = msg
        #
        # The following statement allows passing of a dictionary as a sole
        # argument, so that you can do something like
        #  logging.debug("a %(a)d b %(b)s", {'a':1, 'b':2})
        # Suggested by Stefan Behnel.
        # Note that without the test for args[0], we get a problem because
        # during formatting, we test to see if the arg is present using
        # 'if self.args:'. If the event being logged is e.g. 'Value is %d'
        # and if the passed arg fails 'if self.args:' then no formatting
        # is done. For example, logger.warning('Value is %d', 0) would log
        # 'Value is %d' instead of 'Value is 0'.
        # For the use case of passing a dictionary, this should not be a
        # problem.
        # Issue #21172: a request was made to relax the isinstance check
        # to hasattr(args[0], '__getitem__'). However, the docs on string
        # formatting still seem to suggest a mapping object is required.
        # Thus, while not removing the isinstance check, it does now look
        # for collections.abc.Mapping rather than, as before, dict.
        if (args and len(args) == 1 and isinstance(args[0], collections.abc.Mapping)
            and args[0]):
            args = args[0]
        self.args = args
        self.levelname = getLevelName(level)
        self.levelno = level
        self.pathname = pathname
        try:
            self.filename = os.path.basename(pathname)
            self.module = os.path.splitext(self.filename)[0]
        except (TypeError, ValueError, AttributeError):
            self.filename = pathname
            self.module = "Unknown module"
        self.exc_info = exc_info
        self.exc_text = None      # used to cache the traceback text
        self.stack_info = sinfo
        self.lineno = lineno
        self.funcName = func
        self.created = ct
        self.msecs = (ct - int(ct)) * 1000
        self.relativeCreated = (self.created - _startTime) * 1000
        if logThreads:
            self.thread = threading.get_ident()
            self.threadName = threading.current_thread().name
        else: # pragma: no cover
            self.thread = None
            self.threadName = None
        if not logMultiprocessing: # pragma: no cover
            self.processName = None
        else:
            self.processName = 'MainProcess'
            mp = sys.modules.get('multiprocessing')
            if mp is not None:
                # Errors may occur if multiprocessing has not finished loading
                # yet - e.g. if a custom import hook causes third-party code
                # to run when multiprocessing calls import. See issue 8200
                # for an example
                try:
                    self.processName = mp.current_process().name
                except Exception: #pragma: no cover
                    pass
        if logProcesses and hasattr(os, 'getpid'):
            self.process = os.getpid()
        else:
            self.process = None

def __repr__(self):
        return '<LogRecord: %s, %s, %s, %s, "%s">'%(self.name, self.levelno,
            self.pathname, self.lineno, self.msg)

def getMessage(self):
        """
        Return the message for this LogRecord.

Return the message for this LogRecord after merging any user-supplied
        arguments with the message.
        """
        msg = str(self.msg)
        if self.args:
            msg = msg % self.args
        return msg

#
#   Determine which class to use when instantiating log records.
#
_logRecordFactory = LogRecord

def setLogRecordFactory(factory):
    """
    Set the factory to be used when instantiating a log record.

:param factory: A callable which will be called to instantiate
    a log record.
    """
    global _logRecordFactory
    _logRecordFactory = factory

def getLogRecordFactory():
    """
    Return the factory to be used when instantiating a log record.
    """

return _logRecordFactory

def makeLogRecord(dict):
    """
    Make a LogRecord whose attributes are defined by the specified dictionary,
    This function is useful for converting a logging event received over
    a socket connection (which is sent as a dictionary) into a LogRecord
    instance.
    """
    rv = _logRecordFactory(None, None, "", 0, "", (), None, None)
    rv.__dict__.update(dict)
    return rv

#---------------------------------------------------------------------------
#   Formatter classes and functions
#---------------------------------------------------------------------------
_str_formatter = StrFormatter()
del StrFormatter

class PercentStyle(object):

default_format = '%(message)s'
    asctime_format = '%(asctime)s'
    asctime_search = '%(asctime)'
    validation_pattern = re.compile(r'%$\w+$[#0+ -]*(\*|\d+)?(\.(\*|\d+))?[diouxefgcrsa%]', re.I)

def __init__(self, fmt):
        self._fmt = fmt or self.default_format

def usesTime(self):
        return self._fmt.find(self.asctime_search) >= 0

def validate(self):
        """Validate the input format, ensure it matches the correct style"""
        if not self.validation_pattern.search(self._fmt):
            raise ValueError("Invalid format '%s' for '%s' style" % (self._fmt, self.default_format[0]))

def _format(self, record):
        return self._fmt % record.__dict__

def format(self, record):
        try:
            return self._format(record)
        except KeyError as e:
            raise ValueError('Formatting field not found in record: %s' % e)

class StrFormatStyle(PercentStyle):
    default_format = '{message}'
    asctime_format = '{asctime}'
    asctime_search = '{asctime'

fmt_spec = re.compile(r'^(.?[<>=^])?[+ -]?#?0?(\d+|{\w+})?[,_]?(\.(\d+|{\w+}))?[bcdefgnosx%]?$', re.I)
    field_spec = re.compile(r'^(\d+|\w+)(\.\w+|\[[^]]+\])*$')

def _format(self, record):
        return self._fmt.format(**record.__dict__)

def validate(self):
        """Validate the input format, ensure it is the correct string formatting style"""
        fields = set()
        try:
            for _, fieldname, spec, conversion in _str_formatter.parse(self._fmt):
                if fieldname:
                    if not self.field_spec.match(fieldname):
                        raise ValueError('invalid field name/expression: %r' % fieldname)
                    fields.add(fieldname)
                if conversion and conversion not in 'rsa':
                    raise ValueError('invalid conversion: %r' % conversion)
                if spec and not self.fmt_spec.match(spec):
                    raise ValueError('bad specifier: %r' % spec)
        except ValueError as e:
            raise ValueError('invalid format: %s' % e)
        if not fields:
            raise ValueError('invalid format: no fields')

class StringTemplateStyle(PercentStyle):
    default_format = '${message}'
    asctime_format = '${asctime}'
    asctime_search = '${asctime}'

def __init__(self, fmt):
        self._fmt = fmt or self.default_format
        self._tpl = Template(self._fmt)

def usesTime(self):
        fmt = self._fmt
        return fmt.find('$asctime') >= 0 or fmt.find(self.asctime_format) >= 0

def validate(self):
        pattern = Template.pattern
        fields = set()
        for m in pattern.finditer(self._fmt):
            d = m.groupdict()
            if d['named']:
                fields.add(d['named'])
            elif d['braced']:
                fields.add(d['braced'])
            elif m.group(0) == '$':
                raise ValueError('invalid format: bare \'$\' not allowed')
        if not fields:
            raise ValueError('invalid format: no fields')

def _format(self, record):
        return self._tpl.substitute(**record.__dict__)

BASIC_FORMAT = "%(levelname)s:%(name)s:%(message)s"

_STYLES = {
    '%': (PercentStyle, BASIC_FORMAT),
    '{': (StrFormatStyle, '{levelname}:{name}:{message}'),
    '$': (StringTemplateStyle, '${levelname}:${name}:${message}'),
}

class Formatter(object):
    """
    Formatter instances are used to convert a LogRecord to text.

Formatters need to know how a LogRecord is constructed. They are
    responsible for converting a LogRecord to (usually) a string which can
    be interpreted by either a human or an external system. The base Formatter
    allows a formatting string to be specified. If none is supplied, the
    style-dependent default value, "%(message)s", "{message}", or
    "${message}", is used.

The Formatter can be initialized with a format string which makes use of
    knowledge of the LogRecord attributes - e.g. the default value mentioned
    above makes use of the fact that the user's message and arguments are pre-
    formatted into a LogRecord's message attribute. Currently, the useful
    attributes in a LogRecord are described by:

%(name)s            Name of the logger (logging channel)
    %(levelno)s         Numeric logging level for the message (DEBUG, INFO,
                        WARNING, ERROR, CRITICAL)
    %(levelname)s       Text logging level for the message ("DEBUG", "INFO",
                        "WARNING", "ERROR", "CRITICAL")
    %(pathname)s        Full pathname of the source file where the logging
                        call was issued (if available)
    %(filename)s        Filename portion of pathname
    %(module)s          Module (name portion of filename)
    %(lineno)d          Source line number where the logging call was issued
                        (if available)
    %(funcName)s        Function name
    %(created)f         Time when the LogRecord was created (time.time()
                        return value)
    %(asctime)s         Textual time when the LogRecord was created
    %(msecs)d           Millisecond portion of the creation time
    %(relativeCreated)d Time in milliseconds when the LogRecord was created,
                        relative to the time the logging module was loaded
                        (typically at application startup time)
    %(thread)d          Thread ID (if available)
    %(threadName)s      Thread name (if available)
    %(process)d         Process ID (if available)
    %(message)s         The result of record.getMessage(), computed just as
                        the record is emitted
    """

converter = time.localtime

def __init__(self, fmt=None, datefmt=None, style='%', validate=True):
        """
        Initialize the formatter with specified format strings.

Initialize the formatter either with the specified format string, or a
        default as described above. Allow for specialized date formatting with
        the optional datefmt argument. If datefmt is omitted, you get an
        ISO8601-like (or RFC 3339-like) format.

Use a style parameter of '%', '{' or '$' to specify that you want to
        use one of %-formatting, :meth:`str.format` (``{}``) formatting or
        :class:`string.Template` formatting in your format string.

.. versionchanged:: 3.2
           Added the ``style`` parameter.
        """
        if style not in _STYLES:
            raise ValueError('Style must be one of: %s' % ','.join(
                             _STYLES.keys()))
        self._style = _STYLES[style][0](fmt)
        if validate:
            self._style.validate()

self._fmt = self._style._fmt
        self.datefmt = datefmt

default_time_format = '%Y-%m-%d %H:%M:%S'
    default_msec_format = '%s,%03d'

def formatTime(self, record, datefmt=None):
        """
        Return the creation time of the specified LogRecord as formatted text.

This method should be called from format() by a formatter which
        wants to make use of a formatted time. This method can be overridden
        in formatters to provide for any specific requirement, but the
        basic behaviour is as follows: if datefmt (a string) is specified,
        it is used with time.strftime() to format the creation time of the
        record. Otherwise, an ISO8601-like (or RFC 3339-like) format is used.
        The resulting string is returned. This function uses a user-configurable
        function to convert the creation time to a tuple. By default,
        time.localtime() is used; to change this for a particular formatter
        instance, set the 'converter' attribute to a function with the same
        signature as time.localtime() or time.gmtime(). To change it for all
        formatters, for example if you want all logging times to be shown in GMT,
        set the 'converter' attribute in the Formatter class.
        """
        ct = self.converter(record.created)
        if datefmt:
            s = time.strftime(datefmt, ct)
        else:
            t = time.strftime(self.default_time_format, ct)
            s = self.default_msec_format % (t, record.msecs)
        return s

def formatException(self, ei):
        """
        Format and return the specified exception information as a string.

This default implementation just uses
        traceback.print_exception()
        """
        sio = io.StringIO()
        tb = ei[2]
        # See issues #9427, #1553375. Commented out for now.
        #if getattr(self, 'fullstack', False):
        #    traceback.print_stack(tb.tb_frame.f_back, file=sio)
        traceback.print_exception(ei[0], ei[1], tb, None, sio)
        s = sio.getvalue()
        sio.close()
        if s[-1:] == "\n":
            s = s[:-1]
        return s

def usesTime(self):
        """
        Check if the format uses the creation time of the record.
        """
        return self._style.usesTime()

def formatMessage(self, record):
        return self._style.format(record)

def formatStack(self, stack_info):
        """
        This method is provided as an extension point for specialized
        formatting of stack information.

The input data is a string as returned from a call to
        :func:`traceback.print_stack`, but with the last trailing newline
        removed.

The base implementation just returns the value passed in.
        """
        return stack_info

def format(self, record):
        """
        Format the specified record as text.

The record's attribute dictionary is used as the operand to a
        string formatting operation which yields the returned string.
        Before formatting the dictionary, a couple of preparatory steps
        are carried out. The message attribute of the record is computed
        using LogRecord.getMessage(). If the formatting string uses the
        time (as determined by a call to usesTime(), formatTime() is
        called to format the event time. If there is exception information,
        it is formatted using formatException() and appended to the message.
        """
        record.message = record.getMessage()
        if self.usesTime():
            record.asctime = self.formatTime(record, self.datefmt)
        s = self.formatMessage(record)
        if record.exc_info:
            # Cache the traceback text to avoid converting it multiple times
            # (it's constant anyway)
            if not record.exc_text:
                record.exc_text = self.formatException(record.exc_info)
        if record.exc_text:
            if s[-1:] != "\n":
                s = s + "\n"
            s = s + record.exc_text
        if record.stack_info:
            if s[-1:] != "\n":
                s = s + "\n"
            s = s + self.formatStack(record.stack_info)
        return s

#
#   The default formatter to use when no other is specified
#
_defaultFormatter = Formatter()

class BufferingFormatter(object):
    """
    A formatter suitable for formatting a number of records.
    """
    def __init__(self, linefmt=None):
        """
        Optionally specify a formatter which will be used to format each
        individual record.
        """
        if linefmt:
            self.linefmt = linefmt
        else:
            self.linefmt = _defaultFormatter

def formatHeader(self, records):
        """
        Return the header string for the specified records.
        """
        return ""

def formatFooter(self, records):
        """
        Return the footer string for the specified records.
        """
        return ""

def format(self, records):
        """
        Format the specified records and return the result as a string.
        """
        rv = ""
        if len(records) > 0:
            rv = rv + self.formatHeader(records)
            for record in records:
                rv = rv + self.linefmt.format(record)
            rv = rv + self.formatFooter(records)
        return rv

#---------------------------------------------------------------------------
#   Filter classes and functions
#---------------------------------------------------------------------------

class Filter(object):
    """
    Filter instances are used to perform arbitrary filtering of LogRecords.

Loggers and Handlers can optionally use Filter instances to filter
    records as desired. The base filter class only allows events which are
    below a certain point in the logger hierarchy. For example, a filter
    initialized with "A.B" will allow events logged by loggers "A.B",
    "A.B.C", "A.B.C.D", "A.B.D" etc. but not "A.BB", "B.A.B" etc. If
    initialized with the empty string, all events are passed.
    """
    def __init__(self, name=''):
        """
        Initialize a filter.

Initialize with the name of the logger which, together with its
        children, will have its events allowed through the filter. If no
        name is specified, allow every event.
        """
        self.name = name
        self.nlen = len(name)

def filter(self, record):
        """
        Determine if the specified record is to be logged.

Returns True if the record should be logged, or False otherwise.
        If deemed appropriate, the record may be modified in-place.
        """
        if self.nlen == 0:
            return True
        elif self.name == record.name:
            return True
        elif record.name.find(self.name, 0, self.nlen) != 0:
            return False
        return (record.name[self.nlen] == ".")

class Filterer(object):
    """
    A base class for loggers and handlers which allows them to share
    common code.
    """
    def __init__(self):
        """
        Initialize the list of filters to be an empty list.
        """
        self.filters = []

def addFilter(self, filter):
        """
        Add the specified filter to this handler.
        """
        if not (filter in self.filters):
            self.filters.append(filter)

def removeFilter(self, filter):
        """
        Remove the specified filter from this handler.
        """
        if filter in self.filters:
            self.filters.remove(filter)

def filter(self, record):
        """
        Determine if a record is loggable by consulting all the filters.

The default is to allow the record to be logged; any filter can veto
        this and the record is then dropped. Returns a zero value if a record
        is to be dropped, else non-zero.

.. versionchanged:: 3.2

Allow filters to be just callables.
        """
        rv = True
        for f in self.filters:
            if hasattr(f, 'filter'):
                result = f.filter(record)
            else:
                result = f(record) # assume callable - will raise if not
            if not result:
                rv = False
                break
        return rv

#---------------------------------------------------------------------------
#   Handler classes and functions
#---------------------------------------------------------------------------

_handlers = weakref.WeakValueDictionary()  #map of handler names to handlers
_handlerList = [] # added to allow handlers to be removed in reverse of order initialized

def _removeHandlerRef(wr):
    """
    Remove a handler reference from the internal cleanup list.
    """
    # This function can be called during module teardown, when globals are
    # set to None. It can also be called from another thread. So we need to
    # pre-emptively grab the necessary globals and check if they're None,
    # to prevent race conditions and failures during interpreter shutdown.
    acquire, release, handlers = _acquireLock, _releaseLock, _handlerList
    if acquire and release and handlers:
        acquire()
        try:
            if wr in handlers:
                handlers.remove(wr)
        finally:
            release()

def _addHandlerRef(handler):
    """
    Add a handler to the internal cleanup list using a weak reference.
    """
    _acquireLock()
    try:
        _handlerList.append(weakref.ref(handler, _removeHandlerRef))
    finally:
        _releaseLock()

class Handler(Filterer):
    """
    Handler instances dispatch logging events to specific destinations.

The base handler class. Acts as a placeholder which defines the Handler
    interface. Handlers can optionally use Formatter instances to format
    records as desired. By default, no formatter is specified; in this case,
    the 'raw' message as determined by record.message is logged.
    """
    def __init__(self, level=NOTSET):
        """
        Initializes the instance - basically setting the formatter to None
        and the filter list to empty.
        """
        Filterer.__init__(self)
        self._name = None
        self.level = _checkLevel(level)
        self.formatter = None
        # Add the handler to the global _handlerList (for cleanup on shutdown)
        _addHandlerRef(self)
        self.createLock()

def get_name(self):
        return self._name

def set_name(self, name):
        _acquireLock()
        try:
            if self._name in _handlers:
                del _handlers[self._name]
            self._name = name
            if name:
                _handlers[name] = self
        finally:
            _releaseLock()

name = property(get_name, set_name)

def createLock(self):
        """
        Acquire a thread lock for serializing access to the underlying I/O.
        """
        self.lock = threading.RLock()
        _register_at_fork_reinit_lock(self)

def acquire(self):
        """
        Acquire the I/O thread lock.
        """
        if self.lock:
            self.lock.acquire()

def release(self):
        """
        Release the I/O thread lock.
        """
        if self.lock:
            self.lock.release()

def setLevel(self, level):
        """
        Set the logging level of this handler.  level must be an int or a str.
        """
        self.level = _checkLevel(level)

def format(self, record):
        """
        Format the specified record.

If a formatter is set, use it. Otherwise, use the default formatter
        for the module.
        """
        if self.formatter:
            fmt = self.formatter
        else:
            fmt = _defaultFormatter
        return fmt.format(record)

def emit(self, record):
        """
        Do whatever it takes to actually log the specified logging record.

This version is intended to be implemented by subclasses and so
        raises a NotImplementedError.
        """
        raise NotImplementedError('emit must be implemented '
                                  'by Handler subclasses')

def handle(self, record):
        """
        Conditionally emit the specified logging record.

Emission depends on filters which may have been added to the handler.
        Wrap the actual emission of the record with acquisition/release of
        the I/O thread lock. Returns whether the filter passed the record for
        emission.
        """
        rv = self.filter(record)
        if rv:
            self.acquire()
            try:
                self.emit(record)
            finally:
                self.release()
        return rv

def setFormatter(self, fmt):
        """
        Set the formatter for this handler.
        """
        self.formatter = fmt

def flush(self):
        """
        Ensure all logging output has been flushed.

This version does nothing and is intended to be implemented by
        subclasses.
        """
        pass

def close(self):
        """
        Tidy up any resources used by the handler.

This version removes the handler from an internal map of handlers,
        _handlers, which is used for handler lookup by name. Subclasses
        should ensure that this gets called from overridden close()
        methods.
        """
        #get the module data lock, as we're updating a shared structure.
        _acquireLock()
        try:    #unlikely to raise an exception, but you never know...
            if self._name and self._name in _handlers:
                del _handlers[self._name]
        finally:
            _releaseLock()

def handleError(self, record):
        """
        Handle errors which occur during an emit() call.

This method should be called from handlers when an exception is
        encountered during an emit() call. If raiseExceptions is false,
        exceptions get silently ignored. This is what is mostly wanted
        for a logging system - most users will not care about errors in
        the logging system, they are more interested in application errors.
        You could, however, replace this with a custom handler if you wish.
        The record which was being processed is passed in to this method.
        """
        if raiseExceptions and sys.stderr:  # see issue 13807
            t, v, tb = sys.exc_info()
            try:
                sys.stderr.write('--- Logging error ---\n')
                traceback.print_exception(t, v, tb, None, sys.stderr)
                sys.stderr.write('Call stack:\n')
                # Walk the stack frame up until we're out of logging,
                # so as to print the calling context.
                frame = tb.tb_frame
                while (frame and os.path.dirname(frame.f_code.co_filename) ==
                       __path__[0]):
                    frame = frame.f_back
                if frame:
                    traceback.print_stack(frame, file=sys.stderr)
                else:
                    # couldn't find the right stack frame, for some reason
                    sys.stderr.write('Logged from file %s, line %s\n' % (
                                     record.filename, record.lineno))
                # Issue 18671: output logging message and arguments
                try:
                    sys.stderr.write('Message: %r\n'
                                     'Arguments: %s\n' % (record.msg,
                                                          record.args))
                except RecursionError:  # See issue 36272
                    raise
                except Exception:
                    sys.stderr.write('Unable to print the message and arguments'
                                     ' - possible formatting error.\nUse the'
                                     ' traceback above to help find the error.\n'
                                    )
            except OSError: #pragma: no cover
                pass    # see issue 5971
            finally:
                del t, v, tb

def __repr__(self):
        level = getLevelName(self.level)
        return '<%s (%s)>' % (self.__class__.__name__, level)

class StreamHandler(Handler):
    """
    A handler class which writes logging records, appropriately formatted,
    to a stream. Note that this class does not close the stream, as
    sys.stdout or sys.stderr may be used.
    """

terminator = '\n'

def __init__(self, stream=None):
        """
        Initialize the handler.

If stream is not specified, sys.stderr is used.
        """
        Handler.__init__(self)
        if stream is None:
            stream = sys.stderr
        self.stream = stream

def flush(self):
        """
        Flushes the stream.
        """
        self.acquire()
        try:
            if self.stream and hasattr(self.stream, "flush"):
                self.stream.flush()
        finally:
            self.release()

def emit(self, record):
        """
        Emit a record.

If a formatter is specified, it is used to format the record.
        The record is then written to the stream with a trailing newline.  If
        exception information is present, it is formatted using
        traceback.print_exception and appended to the stream.  If the stream
        has an 'encoding' attribute, it is used to determine how to do the
        output to the stream.
        """
        try:
            msg = self.format(record)
            stream = self.stream
            # issue 35046: merged two stream.writes into one.
            stream.write(msg + self.terminator)
            self.flush()
        except RecursionError:  # See issue 36272
            raise
        except Exception:
            self.handleError(record)

def setStream(self, stream):
        """
        Sets the StreamHandler's stream to the specified value,
        if it is different.

Returns the old stream, if the stream was changed, or None
        if it wasn't.
        """
        if stream is self.stream:
            result = None
        else:
            result = self.stream
            self.acquire()
            try:
                self.flush()
                self.stream = stream
            finally:
                self.release()
        return result

def __repr__(self):
        level = getLevelName(self.level)
        name = getattr(self.stream, 'name', '')
        #  bpo-36015: name can be an int
        name = str(name)
        if name:
            name += ' '
        return '<%s %s(%s)>' % (self.__class__.__name__, name, level)

class FileHandler(StreamHandler):
    """
    A handler class which writes formatted logging records to disk files.
    """
    def __init__(self, filename, mode='a', encoding=None, delay=False):
        """
        Open the specified file and use it as the stream for logging.
        """
        # Issue #27493: add support for Path objects to be passed in
        filename = os.fspath(filename)
        #keep the absolute path, otherwise derived classes which use this
        #may come a cropper when the current directory changes
        self.baseFilename = os.path.abspath(filename)
        self.mode = mode
        self.encoding = encoding
        self.delay = delay
        if delay:
            #We don't open the stream, but we still need to call the
            #Handler constructor to set level, formatter, lock etc.
            Handler.__init__(self)
            self.stream = None
        else:
            StreamHandler.__init__(self, self._open())

def close(self):
        """
        Closes the stream.
        """
        self.acquire()
        try:
            try:
                if self.stream:
                    try:
                        self.flush()
                    finally:
                        stream = self.stream
                        self.stream = None
                        if hasattr(stream, "close"):
                            stream.close()
            finally:
                # Issue #19523: call unconditionally to
                # prevent a handler leak when delay is set
                StreamHandler.close(self)
        finally:
            self.release()

def _open(self):
        """
        Open the current base file with the (original) mode and encoding.
        Return the resulting stream.
        """
        return open(self.baseFilename, self.mode, encoding=self.encoding)

def emit(self, record):
        """
        Emit a record.

If the stream was not opened because 'delay' was specified in the
        constructor, open it before calling the superclass's emit.
        """
        if self.stream is None:
            self.stream = self._open()
        StreamHandler.emit(self, record)

def __repr__(self):
        level = getLevelName(self.level)
        return '<%s %s (%s)>' % (self.__class__.__name__, self.baseFilename, level)

class _StderrHandler(StreamHandler):
    """
    This class is like a StreamHandler using sys.stderr, but always uses
    whatever sys.stderr is currently set to rather than the value of
    sys.stderr at handler construction time.
    """
    def __init__(self, level=NOTSET):
        """
        Initialize the handler.
        """
        Handler.__init__(self, level)

@property
    def stream(self):
        return sys.stderr

_defaultLastResort = _StderrHandler(WARNING)
lastResort = _defaultLastResort

#---------------------------------------------------------------------------
#   Manager classes and functions
#---------------------------------------------------------------------------

class PlaceHolder(object):
    """
    PlaceHolder instances are used in the Manager logger hierarchy to take
    the place of nodes for which no loggers have been defined. This class is
    intended for internal use only and not as part of the public API.
    """
    def __init__(self, alogger):
        """
        Initialize with the specified logger being a child of this placeholder.
        """
        self.loggerMap = { alogger : None }

def append(self, alogger):
        """
        Add the specified logger as a child of this placeholder.
        """
        if alogger not in self.loggerMap:
            self.loggerMap[alogger] = None

#
#   Determine which class to use when instantiating loggers.
#

def setLoggerClass(klass):
    """
    Set the class to be used when instantiating a logger. The class should
    define __init__() such that only a name argument is required, and the
    __init__() should call Logger.__init__()
    """
    if klass != Logger:
        if not issubclass(klass, Logger):
            raise TypeError("logger not derived from logging.Logger: "
                            + klass.__name__)
    global _loggerClass
    _loggerClass = klass

def getLoggerClass():
    """
    Return the class to be used when instantiating a logger.
    """
    return _loggerClass

class Manager(object):
    """
    There is [under normal circumstances] just one Manager instance, which
    holds the hierarchy of loggers.
    """
    def __init__(self, rootnode):
        """
        Initialize the manager with the root node of the logger hierarchy.
        """
        self.root = rootnode
        self.disable = 0
        self.emittedNoHandlerWarning = False
        self.loggerDict = {}
        self.loggerClass = None
        self.logRecordFactory = None

@property
    def disable(self):
        return self._disable

@disable.setter
    def disable(self, value):
        self._disable = _checkLevel(value)

def getLogger(self, name):
        """
        Get a logger with the specified name (channel name), creating it
        if it doesn't yet exist. This name is a dot-separated hierarchical
        name, such as "a", "a.b", "a.b.c" or similar.

If a PlaceHolder existed for the specified name [i.e. the logger
        didn't exist but a child of it did], replace it with the created
        logger and fix up the parent/child references which pointed to the
        placeholder to now point to the logger.
        """
        rv = None
        if not isinstance(name, str):
            raise TypeError('A logger name must be a string')
        _acquireLock()
        try:
            if name in self.loggerDict:
                rv = self.loggerDict[name]
                if isinstance(rv, PlaceHolder):
                    ph = rv
                    rv = (self.loggerClass or _loggerClass)(name)
                    rv.manager = self
                    self.loggerDict[name] = rv
                    self._fixupChildren(ph, rv)
                    self._fixupParents(rv)
            else:
                rv = (self.loggerClass or _loggerClass)(name)
                rv.manager = self
                self.loggerDict[name] = rv
                self._fixupParents(rv)
        finally:
            _releaseLock()
        return rv

def setLoggerClass(self, klass):
        """
        Set the class to be used when instantiating a logger with this Manager.
        """
        if klass != Logger:
            if not issubclass(klass, Logger):
                raise TypeError("logger not derived from logging.Logger: "
                                + klass.__name__)
        self.loggerClass = klass

def setLogRecordFactory(self, factory):
        """
        Set the factory to be used when instantiating a log record with this
        Manager.
        """
        self.logRecordFactory = factory

def _fixupParents(self, alogger):
        """
        Ensure that there are either loggers or placeholders all the way
        from the specified logger to the root of the logger hierarchy.
        """
        name = alogger.name
        i = name.rfind(".")
        rv = None
        while (i > 0) and not rv:
            substr = name[:i]
            if substr not in self.loggerDict:
                self.loggerDict[substr] = PlaceHolder(alogger)
            else:
                obj = self.loggerDict[substr]
                if isinstance(obj, Logger):
                    rv = obj
                else:
                    assert isinstance(obj, PlaceHolder)
                    obj.append(alogger)
            i = name.rfind(".", 0, i - 1)
        if not rv:
            rv = self.root
        alogger.parent = rv

def _fixupChildren(self, ph, alogger):
        """
        Ensure that children of the placeholder ph are connected to the
        specified logger.
        """
        name = alogger.name
        namelen = len(name)
        for c in ph.loggerMap.keys():
            #The if means ... if not c.parent.name.startswith(nm)
            if c.parent.name[:namelen] != name:
                alogger.parent = c.parent
                c.parent = alogger

def _clear_cache(self):
        """
        Clear the cache for all loggers in loggerDict
        Called when level changes are made
        """

_acquireLock()
        for logger in self.loggerDict.values():
            if isinstance(logger, Logger):
                logger._cache.clear()
        self.root._cache.clear()
        _releaseLock()

#---------------------------------------------------------------------------
#   Logger classes and functions
#---------------------------------------------------------------------------

class Logger(Filterer):
    """
    Instances of the Logger class represent a single logging channel. A
    "logging channel" indicates an area of an application. Exactly how an
    "area" is defined is up to the application developer. Since an
    application can have any number of areas, logging channels are identified
    by a unique string. Application areas can be nested (e.g. an area
    of "input processing" might include sub-areas "read CSV files", "read
    XLS files" and "read Gnumeric files"). To cater for this natural nesting,
    channel names are organized into a namespace hierarchy where levels are
    separated by periods, much like the Java or Python package namespace. So
    in the instance given above, channel names might be "input" for the upper
    level, and "input.csv", "input.xls" and "input.gnu" for the sub-levels.
    There is no arbitrary limit to the depth of nesting.
    """
    def __init__(self, name, level=NOTSET):
        """
        Initialize the logger with a name and an optional level.
        """
        Filterer.__init__(self)
        self.name = name
        self.level = _checkLevel(level)
        self.parent = None
        self.propagate = True
        self.handlers = []
        self.disabled = False
        self._cache = {}

def setLevel(self, level):
        """
        Set the logging level of this logger.  level must be an int or a str.
        """
        self.level = _checkLevel(level)
        self.manager._clear_cache()

def debug(self, msg, *args, **kwargs):
        """
        Log 'msg % args' with severity 'DEBUG'.