cvs2svn_lib/log.py

   1 # (Be in -*- python -*- mode.)
   2 #
   3 # ====================================================================
   4 # Copyright (c) 2000-2008 CollabNet.  All rights reserved.
   5 #
   6 # This software is licensed as described in the file COPYING, which
   7 # you should have received as part of this distribution.  The terms
   8 # are also available at http://subversion.tigris.org/license-1.html.
   9 # If newer versions of this license are posted there, you may use a
  10 # newer version instead, at your option.
  11 #
  12 # This software consists of voluntary contributions made by many
  13 # individuals.  For exact contribution history, see the revision
  14 # history and logs, available at http://cvs2svn.tigris.org/.
  15 # ====================================================================
  16
  17 """This module contains a simple logging facility for cvs2svn."""
  18
  19
  20 import sys
  21 import time
  22 import threading
  23
  24
  25 class _Log:
  26   """A Simple logging facility.
  27
  28   If self.log_level is DEBUG or higher, each line will be timestamped
  29   with the number of wall-clock seconds since the time when this
  30   module was first imported.
  31
  32   The public methods of this class are thread-safe."""
  33
  34   # These constants represent the log levels that this class supports.
  35   # The increase_verbosity() and decrease_verbosity() methods rely on
  36   # these constants being consecutive integers:
  37   ERROR = -2
  38   WARN = -1
  39   QUIET = 0
  40   NORMAL = 1
  41   VERBOSE = 2
  42   DEBUG = 3
  43
  44   start_time = time.time()
  45
  46   def __init__(self):
  47     self.log_level = _Log.NORMAL
  48
  49     # The output file to use for errors:
  50     self._err = sys.stderr
  51
  52     # The output file to use for lower-priority messages:
  53     self._out = sys.stdout
  54
  55     # Lock to serialize writes to the log:
  56     self.lock = threading.Lock()
  57
  58   def increase_verbosity(self):
  59     self.lock.acquire()
  60     try:
  61       self.log_level = min(self.log_level + 1, _Log.DEBUG)
  62     finally:
  63       self.lock.release()
  64
  65   def decrease_verbosity(self):
  66     self.lock.acquire()
  67     try:
  68       self.log_level = max(self.log_level - 1, _Log.ERROR)
  69     finally:
  70       self.lock.release()
  71
  72   def is_on(self, level):
  73     """Return True iff messages at the specified LEVEL are currently on.
  74
  75     LEVEL should be one of the constants _Log.WARN, _Log.QUIET, etc."""
  76
  77     return self.log_level >= level
  78
  79   def _timestamp(self):
  80     """Return a timestamp if needed, as a string with a trailing space."""
  81
  82     retval = []
  83
  84     if self.log_level >= _Log.DEBUG:
  85       retval.append('%f: ' % (time.time() - self.start_time,))
  86
  87     return ''.join(retval)
  88
  89   def _write(self, out, *args):
  90     """Write a message to OUT.
  91
  92     If there are multiple ARGS, they will be separated by spaces.  If
  93     there are multiple lines, they will be output one by one with the
  94     same timestamp prefix."""
  95
  96     timestamp = self._timestamp()
  97     s = ' '.join(map(str, args))
  98     lines = s.split('\n')
  99     if lines and not lines[-1]:
 100       del lines[-1]
 101
 102     self.lock.acquire()
 103     try:
 104       for s in lines:
 105         out.write('%s%s\n' % (timestamp, s,))
 106       # Ensure that log output doesn't get out-of-order with respect to
 107       # stderr output.
 108       out.flush()
 109     finally:
 110       self.lock.release()
 111
 112   def write(self, *args):
 113     """Write a message to SELF._out.
 114
 115     This is a public method to use for writing to the output log
 116     unconditionally."""
 117
 118     self._write(self._out, *args)
 119
 120   def error(self, *args):
 121     """Log a message at the ERROR level."""
 122
 123     if self.is_on(_Log.ERROR):
 124       self._write(self._err, *args)
 125
 126   def warn(self, *args):
 127     """Log a message at the WARN level."""
 128
 129     if self.is_on(_Log.WARN):
 130       self._write(self._out, *args)
 131
 132   def quiet(self, *args):
 133     """Log a message at the QUIET level."""
 134
 135     if self.is_on(_Log.QUIET):
 136       self._write(self._out, *args)
 137
 138   def normal(self, *args):
 139     """Log a message at the NORMAL level."""
 140
 141     if self.is_on(_Log.NORMAL):
 142       self._write(self._out, *args)
 143
 144   def verbose(self, *args):
 145     """Log a message at the VERBOSE level."""
 146
 147     if self.is_on(_Log.VERBOSE):
 148       self._write(self._out, *args)
 149
 150   def debug(self, *args):
 151     """Log a message at the DEBUG level."""
 152
 153     if self.is_on(_Log.DEBUG):
 154       self._write(self._out, *args)
 155
 156
 157 # Create an instance that everybody can use:
 158 logger = _Log()
 159
 160