python/google/appengine/api/app_logging.py

   1 #!/usr/bin/env python
   2 #
   3 # Copyright 2007 Google Inc.
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16 #
  17
  18
  19
  20
  21
  22 """Logging utilities for use by applications.
  23
  24 Classes defined here:
  25   AppLogsHandler: StreamHandler subclass
  26 """
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  36 import logging
  37
  38 from google.appengine import runtime
  39 from google.appengine.api import logservice
  40
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  42
  43
  44 NEWLINE_REPLACEMENT = "\0"
  45
  46 class AppLogsHandler(logging.Handler):
  47   """Logging handler that will direct output to a persistent store of
  48   application logs.
  49
  50   This handler will output log statements to logservice.write(). This handler is
  51   automatically initialized and attached to the Python common logging library.
  52   """
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  66
  67   def emit(self, record):
  68     """Emit a record.
  69
  70     This implementation is based on the implementation of
  71     StreamHandler.emit()."""
  72     try:
  73       message = self._AppLogsMessage(record)
  74       if isinstance(message, unicode):
  75         message = message.encode("UTF-8")
  76
  77
  78       logservice.write(message)
  79     except (KeyboardInterrupt, SystemExit, runtime.DeadlineExceededError):
  80       raise
  81     except:
  82       self.handleError(record)
  83
  84   def _AppLogsMessage(self, record):
  85     """Converts the log record into a log line."""
  86
  87
  88
  89     message = self.format(record).replace("\r\n", NEWLINE_REPLACEMENT)
  90     message = message.replace("\r", NEWLINE_REPLACEMENT)
  91     message = message.replace("\n", NEWLINE_REPLACEMENT)
  92
  93     return "LOG %d %d %s\n" % (self._AppLogsLevel(record.levelno),
  94                                long(record.created * 1000 * 1000),
  95                                message)
  96
  97   def _AppLogsLevel(self, level):
  98     """Converts the logging level used in Python to the API logging level"""
  99     if level >= logging.CRITICAL:
 100       return 4
 101     elif level >= logging.ERROR:
 102       return 3
 103     elif level >= logging.WARNING:
 104       return 2
 105     elif level >= logging.INFO:
 106       return 1
 107     else:
 108       return 0