cpython/Lib/logging/__init__.py at 3.15 · python/cpython · GitHub

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# Copyright 2001-2022 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.

Copyright (C) 2001-2022 Vinay Sajip. All Rights Reserved.

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

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

from types import GenericAlias
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', 'getLevelNamesMapping',
           'getHandlerByName', 'getHandlerNames']

import threading

__author__  = "Vinay Sajip <vinay_sajip@red-dove.com>"
__status__  = "production"

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

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

#
#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 False
#
logThreads = True

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

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

#
# If you don't want asyncio task information in the log, set this to False
#
logAsyncioTasks = 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 getLevelNamesMapping():
    return _nameToLevel.copy()

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.
    """
    with _lock:
        _levelToName[level] = levelName
        _nameToLevel[levelName] = level

if hasattr(sys, "_getframe"):
    currentframe = lambda: sys._getframe(1)
else: #pragma: no cover
    def currentframe():
        """Return the frame object for the caller's stack frame."""
        try:
            raise Exception
        except Exception as exc:
            return exc.__traceback__.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().
# Setting _srcfile to None will prevent findCaller() from being called. This
# way, you can avoid the overhead of fetching caller information.

# The following is based on warnings._is_internal_frame. It makes sure that
# frames of the import mechanism are skipped when logging at module level and
# using a stacklevel value greater than one.
def _is_internal_frame(frame):
    """Signal whether the frame is a CPython or logging module internal."""
    filename = os.path.normcase(frame.f_code.co_filename)
    return filename == _srcfile or (
        "importlib" in filename and "_bootstrap" in filename
    )


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 _prepareFork():
    """
    Prepare to fork a new child process by acquiring the module-level lock.

    This should be used in conjunction with _afterFork().
    """
    # Wrap the lock acquisition in a try-except to prevent the lock from being
    # abandoned in the event of an asynchronous exception. See gh-106238.
    try:
        _lock.acquire()
    except BaseException:
        _lock.release()
        raise

def _afterFork():
    """
    After a new child process has been forked, release the module-level lock.

    This should be used in conjunction with _prepareFork().
    """
    _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 _at_fork_reinit method (logging.Handler)
    # to be called in the child after forking.  The weakref avoids us keeping
    # discarded Handler instances alive.
    _at_fork_reinit_lock_weakset = weakref.WeakSet()

    def _register_at_fork_reinit_lock(instance):
        with _lock:
            _at_fork_reinit_lock_weakset.add(instance)

    def _after_at_fork_child_reinit_locks():
        for handler in _at_fork_reinit_lock_weakset:
            handler._at_fork_reinit()

        # _prepareFork() was called in the parent before forking.
        # The lock is reinitialized to unlocked state.
        _lock._at_fork_reinit()

    os.register_at_fork(before=_prepareFork,
                        after_in_child=_after_at_fork_child_reinit_locks,
                        after_in_parent=_afterFork)


#---------------------------------------------------------------------------
#   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_ns()
        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 / 1e9  # ns to float seconds
        # Get the number of whole milliseconds (0-999) in the fractional part of seconds.
        # Eg: 1_677_903_920_999_998_503 ns --> 999_998_503 ns--> 999 ms
        # Convert to float by adding 0.0 for historical reasons. See gh-89047
        self.msecs = (ct % 1_000_000_000) // 1_000_000 + 0.0
        if self.msecs == 999.0 and int(self.created) != ct // 1_000_000_000:
            # ns -> sec conversion can round up, e.g:
            # 1_677_903_920_999_999_900 ns --> 1_677_903_921.0 sec
            self.msecs = 0.0

        self.relativeCreated = (ct - _startTime) / 1e6
        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

        self.taskName = None
        if logAsyncioTasks:
            asyncio = sys.modules.get('asyncio')
            if asyncio:
                try:
                    self.taskName = asyncio.current_task().get_name()
                except Exception:
                    pass

    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, *, defaults=None):
        self._fmt = fmt or self.default_format
        self._defaults = defaults

    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):
        if defaults := self._defaults:
            values = defaults | record.__dict__
        else:
            values = record.__dict__
        return self._fmt % values

    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):
        if defaults := self._defaults:
            values = defaults | record.__dict__
        else:
            values = record.__dict__
        return self._fmt.format(**values)

    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, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._tpl = Template(self._fmt)

    def usesTime(self):
        fmt = self._fmt
        return fmt.find('$asctime') >= 0 or fmt.find(self.asctime_search) >= 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):
        if defaults := self._defaults:
            values = defaults | record.__dict__
        else:
            values = record.__dict__
        return self._tpl.substitute(**values)


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_ns() / 1e9
                        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)
    %(taskName)s        Task name (if available)
    %(process)d         Process ID (if available)
    %(processName)s     Process name (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, *,
                 defaults=None):
        """
        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, defaults=defaults)
        if validate:
            self._style.validate()

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

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

    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:
            s = time.strftime(self.default_time_format, ct)
            if self.default_msec_format:
                s = self.default_msec_format % (s, 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, limit=None, file=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 __repr__(self):
        return '<%s (%s)>' % (self.__class__.__name__, self.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 by returning a false value.
        If a filter attached to a handler returns a log record instance,
        then that instance is used in place of the original log record in
        any further processing of the event by that handler.
        If a filter returns any other true value, the original log record
        is used in any further processing of the event by that handler.

        If none of the filters return false values, this method returns
        a log record.
        If any of the filters return a false value, this method returns
        a false value.

        .. versionchanged:: 3.2

           Allow filters to be just callables.

        .. versionchanged:: 3.12
           Allow filters to return a LogRecord instead of
           modifying it in place.
        """
        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:
                return False
            if isinstance(result, LogRecord):
                record = result
        return record

#---------------------------------------------------------------------------
#   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.
    handlers, lock = _handlerList, _lock
    if lock and handlers:
        with lock:
            try:
                handlers.remove(wr)
            except ValueError:
                pass

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


def getHandlerByName(name):
    """
    Get a handler with the specified *name*, or None if there isn't one with
    that name.
    """
    return _handlers.get(name)


def getHandlerNames():
    """
    Return all known handler names as an immutable set.
    """
    return frozenset(_handlers)


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
        self._closed = False
        # 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):
        with _lock:
            if self._name in _handlers:
                del _handlers[self._name]
            self._name = name
            if name:
                _handlers[name] = self

    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 _at_fork_reinit(self):
        self.lock._at_fork_reinit()

    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: