1 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 # Use of this source code is governed by a BSD-style license that can be
3 # found in the LICENSE file.
5 ''' Utility functions and objects for logging.
11 class StdoutStderrHandler(logging.Handler):
12 ''' Subclass of logging.Handler which outputs to either stdout or stderr
13 based on a threshold level.
16 def __init__(self, threshold=logging.WARNING, err=sys.stderr, out=sys.stdout):
18 threshold: below this logging level messages are sent to stdout,
19 otherwise they are sent to stderr
20 err: a stream object that error messages are sent to, defaults to
22 out: a stream object that non-error messages are sent to, defaults to
25 logging.Handler.__init__(self)
26 self._err = logging.StreamHandler(err)
27 self._out = logging.StreamHandler(out)
28 self._threshold = threshold
29 self._last_was_err = False
31 def setLevel(self, lvl):
32 logging.Handler.setLevel(self, lvl)
33 self._err.setLevel(lvl)
34 self._out.setLevel(lvl)
36 def setFormatter(self, formatter):
37 logging.Handler.setFormatter(self, formatter)
38 self._err.setFormatter(formatter)
39 self._out.setFormatter(formatter)
41 def emit(self, record):
42 if record.levelno < self._threshold:
43 self._out.emit(record)
44 self._last_was_err = False
46 self._err.emit(record)
47 self._last_was_err = False
50 # preserve order on the flushing, the stalest stream gets flushed first
51 if self._last_was_err:
59 FORMAT = "%(asctime)s %(filename)s [%(levelname)s] %(message)s"
62 def config_root(level=logging.INFO, threshold=logging.WARNING, format=FORMAT,
64 ''' Configure the root logger to use a StdoutStderrHandler and some default
67 level: messages below this level are ignored
68 threshold: below this logging level messages are sent to stdout,
69 otherwise they are sent to stderr
70 format: format for log messages, see logger.Format
71 datefmt: format for date in log messages
74 # to set the handler of the root logging object, we need to do setup
75 # manually rather than using basicConfig
76 root = logging.getLogger()
78 formatter = logging.Formatter(format, datefmt)
79 handler = StdoutStderrHandler(threshold=threshold)
80 handler.setLevel(level)
81 handler.setFormatter(formatter)
82 root.addHandler(handler)