# Copyright 2001-2016 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) 2001-2016 Vinay Sajip. All Rights Reserved.
To use, simply 'import logging.handlers' and log away!
import logging, socket, os, pickle, struct, time, re
from stat import ST_DEV, ST_INO, ST_MTIME
except ImportError: #pragma: no cover
DEFAULT_TCP_LOGGING_PORT = 9020
DEFAULT_UDP_LOGGING_PORT = 9021
DEFAULT_HTTP_LOGGING_PORT = 9022
DEFAULT_SOAP_LOGGING_PORT = 9023
_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.
def __init__(self, filename, mode, encoding=None, delay=False):
Use the specified filename for streamed logging
logging.FileHandler.__init__(self, filename, mode, encoding, delay)
Output the record to the file, catering for rollover as described
if self.shouldRollover(record):
logging.FileHandler.emit(self, 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
:param default_name: The default name for the log file.
if not callable(self.namer):
result = self.namer(default_name)
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):
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):
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
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.
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
BaseRotatingHandler.__init__(self, filename, mode, encoding, delay)
self.backupCount = backupCount
Do a rollover, as described in __init__().
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,
dfn = self.rotation_filename(self.baseFilename + ".1")
self.rotate(self.baseFilename, dfn)
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
# See bpo-45401: Never rollover anything other than regular files
if os.path.exists(self.baseFilename) and not os.path.isfile(self.baseFilename):
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:
class TimedRotatingFileHandler(BaseRotatingHandler):
Handler for logging to a file, rotating the log file at certain timed
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):
BaseRotatingHandler.__init__(self, filename, 'a', encoding, delay)
self.backupCount = backupCount
# 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:
# 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
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+)?$"
self.interval = 60 # one minute
self.suffix = "%Y-%m-%d_%H-%M"
self.extMatch = r"^\d{4}-\d{2}-\d{2}_\d{2}-\d{2}(\.\w+)?$"
self.interval = 60 * 60 # one hour
self.suffix = "%Y-%m-%d_%H"
self.extMatch = r"^\d{4}-\d{2}-\d{2}_\d{2}(\.\w+)?$"
elif self.when == 'D' or self.when == 'MIDNIGHT':
self.interval = 60 * 60 * 24 # one day
self.extMatch = r"^\d{4}-\d{2}-\d{2}(\.\w+)?$"
elif self.when.startswith('W'):
self.interval = 60 * 60 * 24 * 7 # one week
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.extMatch = r"^\d{4}-\d{2}-\d{2}(\.\w+)?$"
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]
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
t = time.gmtime(currentTime)
t = time.localtime(currentTime)
# r is the number of seconds left between now and the next rotation
rotate_ts = ((self.atTime.hour * 60 + self.atTime.minute)*60 +
r = rotate_ts - ((currentHour * 60 + currentMinute) * 60 +
# Rotate time is before the current time (for example when
# self.rotateAt is 13:45 and it now 14:15), rotation is
currentDay = (currentDay + 1) % 7
# 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:
daysToWait = self.dayOfWeek - day
daysToWait = 6 - day + self.dayOfWeek + 1
newRolloverAt = result + (daysToWait * (60 * 60 * 24))
dstAtRollover = time.localtime(newRolloverAt)[-1]
if dstNow != dstAtRollover:
if not dstNow: # DST kicks in before next rollover, so we need to deduct an hour
else: # DST bows out before next rollover, so we need to add an hour
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
# See bpo-45401: Never rollover anything other than regular files
if os.path.exists(self.baseFilename) and not os.path.isfile(self.baseFilename):
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)
for fileName in fileNames:
if fileName[:plen] == prefix:
if self.extMatch.match(suffix):
result.append(os.path.join(dirName, fileName))
if len(result) < self.backupCount:
result = result[:len(result) - self.backupCount]
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.
# 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
timeTuple = time.gmtime(t)
timeTuple = time.localtime(t)
timeTuple = time.localtime(t + addend)
dfn = self.rotation_filename(self.baseFilename + "." +
time.strftime(self.suffix, timeTuple))
self.rotate(self.baseFilename, dfn)
for s in self.getFilesToDelete():
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
else: # DST bows out before next rollover, so we need to add an hour
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.
def __init__(self, filename, mode='a', encoding=None, delay=False):
logging.FileHandler.__init__(self, filename, mode, encoding, delay)
self.dev, self.ino = -1, -1
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
# 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
# stat the file by path, checking for existence
sres = os.stat(self.baseFilename)
except FileNotFoundError:
# 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 = None # See Issue #21742: _open () might fail.
# open a new file handle and get new stat info from that fd
self.stream = self._open()
If underlying file has changed, reopen the file before emitting the
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
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