[Python-checkins] cpython: Added respect_handler_level to QueueListener.

Mon Feb 9 20:49:10 CET 2015

https://hg.python.org/cpython/rev/e548ab4ce71d
changeset: 94573:e548ab4ce71d
user: Vinay Sajip <vinay_sajip at yahoo.co.uk>
date: Mon Feb 09 19:49:00 2015 +0000
summary:
 Added respect_handler_level to QueueListener.
files:
 Doc/howto/logging-cookbook.rst | 9 +++++++++
 Doc/library/logging.handlers.rst | 11 +++++++++--
 Lib/logging/handlers.py | 14 ++++++++++----
 Lib/test/test_logging.py | 19 +++++++++++++++++++
 Misc/NEWS | 3 +++
 5 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/Doc/howto/logging-cookbook.rst b/Doc/howto/logging-cookbook.rst
--- a/Doc/howto/logging-cookbook.rst
+++ b/Doc/howto/logging-cookbook.rst
@@ -325,6 +325,15 @@
 
 MainThread: Look out!
 
+.. versionchanged:: 3.5
+ Prior to Python 3.5, the :class:`QueueListener` always passed every message
+ received from the queue to every handler it was initialized with. (This was
+ because it was assumed that level filtering was all done on the other side,
+ where the queue is filled.) From 3.5 onwards, this behaviour can be changed
+ by passing a keyword argument ``respect_handler_level=True`` to the
+ listener's constructor. When this is done, the listener compares the level
+ of each message with the handler's level, and only passes a message to a
+ handler if it's appropriate to do so.
 
 .. _network-logging:
 
diff --git a/Doc/library/logging.handlers.rst b/Doc/library/logging.handlers.rst
--- a/Doc/library/logging.handlers.rst
+++ b/Doc/library/logging.handlers.rst
@@ -953,13 +953,20 @@
 possible, while any potentially slow operations (such as sending an email via
 :class:`SMTPHandler`) are done on a separate thread.
 
-.. class:: QueueListener(queue, *handlers)
+.. class:: QueueListener(queue, *handlers, respect_handler_level=False)
 
 Returns a new instance of the :class:`QueueListener` class. The instance is
 initialized with the queue to send messages to and a list of handlers which
 will handle entries placed on the queue. The queue can be any queue-
 like object; it's passed as-is to the :meth:`dequeue` method, which needs
- to know how to get messages from it.
+ to know how to get messages from it. If ``respect_handler_level`` is ``True``,
+ a handler's level is respected (compared with the level for the message) when
+ deciding whether to pass messages to that handler; otherwise, the behaviour
+ is as in previous Python versions - to always pass each message to each
+ handler.
+
+ .. versionchanged:: 3.5
+ The ``respect_handler_levels`` argument was added.
 
 .. method:: dequeue(block)
 
diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
--- a/Lib/logging/handlers.py
+++ b/Lib/logging/handlers.py
@@ -1,4 +1,4 @@
-# Copyright 2001-2013 by Vinay Sajip. All Rights Reserved.
+# Copyright 2001-2015 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,
@@ -18,7 +18,7 @@
 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) 2001-2013 Vinay Sajip. All Rights Reserved.
+Copyright (C) 2001-2015 Vinay Sajip. All Rights Reserved.
 
 To use, simply 'import logging.handlers' and log away!
 """
@@ -1350,7 +1350,7 @@
 """
 _sentinel = None
 
- def __init__(self, queue, *handlers):
+ def __init__(self, queue, *handlers, respect_handler_level=False):
 """
 Initialise an instance with the specified queue and
 handlers.
@@ -1359,6 +1359,7 @@
 self.handlers = handlers
 self._stop = threading.Event()
 self._thread = None
+ self.respect_handler_level = respect_handler_level
 
 def dequeue(self, block):
 """
@@ -1399,7 +1400,12 @@
 """
 record = self.prepare(record)
 for handler in self.handlers:
- handler.handle(record)
+ if not self.respect_handler_level:
+ process = True
+ else:
+ process = record.levelno >= handler.level
+ if process:
+ handler.handle(record)
 
 def _monitor(self):
 """
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -3006,6 +3006,25 @@
 self.assertTrue(handler.matches(levelno=logging.WARNING, message='1'))
 self.assertTrue(handler.matches(levelno=logging.ERROR, message='2'))
 self.assertTrue(handler.matches(levelno=logging.CRITICAL, message='3'))
+ handler.close()
+
+ # Now test with respect_handler_level set
+
+ handler = support.TestHandler(support.Matcher())
+ handler.setLevel(logging.CRITICAL)
+ listener = logging.handlers.QueueListener(self.queue, handler,
+ respect_handler_level=True)
+ listener.start()
+ try:
+ self.que_logger.warning(self.next_message())
+ self.que_logger.error(self.next_message())
+ self.que_logger.critical(self.next_message())
+ finally:
+ listener.stop()
+ self.assertFalse(handler.matches(levelno=logging.WARNING, message='4'))
+ self.assertFalse(handler.matches(levelno=logging.ERROR, message='5'))
+ self.assertTrue(handler.matches(levelno=logging.CRITICAL, message='6'))
+
 
 ZERO = datetime.timedelta(0)
 
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -13,6 +13,9 @@
 Library
 -------
 
+- logging.handlers.QueueListener now takes a respect_handler_level keyword
+ argument which, if set to True, will pass messages to handlers taking handler
+ levels into account.
 
 What's New in Python 3.5 alpha 1?
 =================================
-- 
Repository URL: https://hg.python.org/cpython
