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| 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. |
| 4 |
| 5 ''' Utility functions and objects for logging. |
| 6 ''' |
| 7 |
| 8 import logging |
| 9 import sys |
| 10 |
| 11 class StdoutStderrHandler(logging.Handler): |
| 12 ''' Subclass of logging.Handler which outputs to either stdout or stderr |
| 13 based on a threshold level. |
| 14 ''' |
| 15 |
| 16 def __init__(self, threshold=logging.WARNING, err=sys.stderr, out=sys.stdout): |
| 17 ''' Args: |
| 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 |
| 21 sys.stderr |
| 22 out: a stream object that non-error messages are sent to, defaults to |
| 23 sys.stdout |
| 24 ''' |
| 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 |
| 30 |
| 31 def setLevel(self, lvl): |
| 32 logging.Handler.setLevel(self, lvl) |
| 33 self._err.setLevel(lvl) |
| 34 self._out.setLevel(lvl) |
| 35 |
| 36 def setFormatter(self, formatter): |
| 37 logging.Handler.setFormatter(self, formatter) |
| 38 self._err.setFormatter(formatter) |
| 39 self._out.setFormatter(formatter) |
| 40 |
| 41 def emit(self, record): |
| 42 if record.levelno < self._threshold: |
| 43 self._out.emit(record) |
| 44 self._last_was_err = False |
| 45 else: |
| 46 self._err.emit(record) |
| 47 self._last_was_err = False |
| 48 |
| 49 def flush(self): |
| 50 # preserve order on the flushing, the stalest stream gets flushed first |
| 51 if self._last_was_err: |
| 52 self._out.flush() |
| 53 self._err.flush() |
| 54 else: |
| 55 self._err.flush() |
| 56 self._out.flush() |
| 57 |
| 58 |
| 59 FORMAT = "%(asctime)s %(filename)s [%(levelname)s] %(message)s" |
| 60 DATEFMT = "%H:%M:%S" |
| 61 |
| 62 def config_root(level=logging.INFO, threshold=logging.WARNING, format=FORMAT, |
| 63 datefmt=DATEFMT): |
| 64 ''' Configure the root logger to use a StdoutStderrHandler and some default |
| 65 formatting. |
| 66 Args: |
| 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 |
| 72 |
| 73 ''' |
| 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() |
| 77 root.setLevel(level) |
| 78 formatter = logging.Formatter(format, datefmt) |
| 79 handler = StdoutStderrHandler(threshold=threshold) |
| 80 handler.setLevel(level) |
| 81 handler.setFormatter(formatter) |
| 82 root.addHandler(handler) |
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