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
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  20
  21
  22 """Logging utilities for use by applications.
  23
  24 Classes defined here:
  25   AppLogsHandler: StreamHandler subclass
  26 """
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  37 import logging
  38
  39 from google.appengine import runtime
  40 from google.appengine.api import logservice
  41
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  44
  45 NEWLINE_REPLACEMENT = "\0"
  46
  47 class AppLogsHandler(logging.Handler):
  48   """Logging handler that will direct output to a persistent store of
  49   application logs.
  50
  51   This handler will output log statements to logservice.write(). This handler is
  52   automatically initialized and attached to the Python common logging library.
  53   """
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  68   def emit(self, record):
  69     """Emit a record.
  70
  71     This implementation is based on the implementation of
  72     StreamHandler.emit()."""
  73     try:
  74       message = self._AppLogsMessage(record)
  75       if isinstance(message, unicode):
  76         message = message.encode("UTF-8")
  77
  78
  79       logservice.write(message)
  80     except (KeyboardInterrupt, SystemExit, runtime.DeadlineExceededError):
  81       raise
  82     except:
  83       self.handleError(record)
  84
  85   def _AppLogsMessage(self, record):
  86     """Converts the log record into a log line."""
  87
  88
  89
  90     message = self.format(record).replace("\r\n", NEWLINE_REPLACEMENT)
  91     message = message.replace("\r", NEWLINE_REPLACEMENT)
  92     message = message.replace("\n", NEWLINE_REPLACEMENT)
  93
  94     return "LOG %d %d %s\n" % (self._AppLogsLevel(record.levelno),
  95                                long(record.created * 1000 * 1000),
  96                                message)
  97
  98   def _AppLogsLevel(self, level):
  99     """Converts the logging level used in Python to the API logging level"""
 100     if level >= logging.CRITICAL:
 101       return 4
 102     elif level >= logging.ERROR:
 103       return 3
 104     elif level >= logging.WARNING:
 105       return 2
 106     elif level >= logging.INFO:
 107       return 1
 108     else:
 109       return 0