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Diffstat (limited to 'Doc/library/logging.handlers.rst')
| -rw-r--r-- | Doc/library/logging.handlers.rst | 101 |
1 files changed, 100 insertions, 1 deletions
diff --git a/Doc/library/logging.handlers.rst b/Doc/library/logging.handlers.rst index c4dd438..51e476b 100644 --- a/Doc/library/logging.handlers.rst +++ b/Doc/library/logging.handlers.rst @@ -164,6 +164,87 @@ this value. changed. If it has, the existing stream is flushed and closed and the file opened again, before outputting the record to the file. +.. _base-rotating-handler: + +BaseRotatingHandler +^^^^^^^^^^^^^^^^^^^ + +The :class:`BaseRotatingHandler` class, located in the :mod:`logging.handlers` +module, is the base class for the rotating file handlers, +:class:`RotatingFileHandler` and :class:`TimedRotatingFileHandler`. You should +not need to instantiate this class, but it has attributes and methods you may +need to override. + +.. class:: BaseRotatingHandler(filename, mode, encoding=None, delay=False) + + The parameters are as for :class:`FileHandler`. The attributes are: + + .. attribute:: namer + + If this attribute is set to a callable, the :meth:`rotation_filename` + method delegates to this callable. The parameters passed to the callable + are those passed to :meth:`rotation_filename`. + + .. note:: The namer function is called quite a few times during rollover, + so it should be as simple and as fast as possible. It should also + return the same output every time for a given input, otherwise the + rollover behaviour may not work as expected. + + .. versionadded:: 3.3 + + + .. attribute:: BaseRotatingHandler.rotator + + If this attribute is set to a callable, the :meth:`rotate` method + delegates to this callable. The parameters passed to the callable are + those passed to :meth:`rotate`. + + .. versionadded:: 3.3 + + .. method:: BaseRotatingHandler.rotation_filename(default_name) + + Modify the filename of a log file when rotating. + + This is provided so that a custom filename can be provided. + + The default implementation calls the 'namer' attribute of the handler, + if it's callable, passing the default name to it. If the attribute isn't + callable (the default is ``None``), the name is returned unchanged. + + :param default_name: The default name for the log file. + + .. versionadded:: 3.3 + + + .. method:: BaseRotatingHandler.rotate(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'. + + .. versionadded:: 3.3 + +The reason the attributes exist is to save you having to subclass - you can use +the same callables for instances of :class:`RotatingFileHandler` and +:class:`TimedRotatingFileHandler`. If either the namer or rotator callable +raises an exception, this will be handled in the same way as any other +exception during an :meth:`emit` call, i.e. via the :meth:`handleError` method +of the handler. + +If you need to make more significant changes to rotation processing, you can +override the methods. + +For an example, see :ref:`cookbook-rotator-namer`. + + .. _rotating-file-handler: RotatingFileHandler @@ -452,6 +533,15 @@ supports sending logging messages to a remote or local Unix syslog. behaviour) but can be set to ``False`` on a ``SysLogHandler`` instance in order for that instance to *not* append the NUL terminator. + .. versionchanged:: 3.3 + (See: :issue:`12419`.) In earlier versions, there was no facility for + an "ident" or "tag" prefix to identify the source of the message. This + can now be specified using a class-level attribute, defaulting to + ``""`` to preserve existing behaviour, but which can be overridden on + a ``SysLogHandler`` instance in order for that instance to prepend + the ident to every message handled. Note that the provided ident must + be text, not bytes, and is prepended to the message exactly as is. + .. method:: encodePriority(facility, priority) Encodes the facility and priority into an integer. You can pass in strings @@ -690,7 +780,7 @@ should, then :meth:`flush` is expected to do the needful. .. method:: close() - Calls :meth:`flush`, sets the target to :const:`None` and clears the + Calls :meth:`flush`, sets the target to ``None`` and clears the buffer. @@ -859,6 +949,15 @@ possible, while any potentially slow operations (such as sending an email via Note that if you don't call this before your application exits, there may be some records still left on the queue, which won't be processed. + .. method:: enqueue_sentinel() + + Writes a sentinel to the queue to tell the listener to quit. This + implementation uses ``put_nowait()``. You may want to override this + method if you want to use timeouts or work with custom queue + implementations. + + .. versionadded:: 3.3 + .. seealso:: |