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   If self.use_timestamps is True, each line will be timestamped with a
  33   human-readable clock time.
  34
  35   The public methods of this class are thread-safe.
  36
  37   This class is a Borg; see
  38   http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66531."""
  39
  40   # These constants represent the log levels that this class supports.
  41   # The increase_verbosity() and decrease_verbosity() methods rely on
  42   # these constants being consecutive integers:
  43   ERROR = -2
  44   WARN = -1
  45   QUIET = 0
  46   NORMAL = 1
  47   VERBOSE = 2
  48   DEBUG = 3
  49
  50   start_time = time.time()
  51
  52   __shared_state = {}
  53
  54   def __init__(self):
  55     self.__dict__ = self.__shared_state
  56     if self.__dict__:
  57       return
  58
  59     self.log_level = Log.NORMAL
  60
  61     # Set this to True if you want to see timestamps on each line output.
  62     self.use_timestamps = False
  63
  64     # The output file to use for errors:
  65     self._err = sys.stderr
  66
  67     # The output file to use for lower-priority messages:
  68     self._out = sys.stdout
  69
  70     # Lock to serialize writes to the log:
  71     self.lock = threading.Lock()
  72
  73   def increase_verbosity(self):
  74     self.lock.acquire()
  75     try:
  76       self.log_level = min(self.log_level + 1, Log.DEBUG)
  77     finally:
  78       self.lock.release()
  79
  80   def decrease_verbosity(self):
  81     self.lock.acquire()
  82     try:
  83       self.log_level = max(self.log_level - 1, Log.ERROR)
  84     finally:
  85       self.lock.release()
  86
  87   def is_on(self, level):
  88     """Return True iff messages at the specified LEVEL are currently on.
  89
  90     LEVEL should be one of the constants Log.WARN, Log.QUIET, etc."""
  91
  92     return self.log_level >= level
  93
  94   def _timestamp(self):
  95     """Return a timestamp if needed, as a string with a trailing space."""
  96
  97     retval = []
  98
  99     if self.log_level >= Log.DEBUG:
 100       retval.append('%f: ' % (time.time() - self.start_time,))
 101
 102     if self.use_timestamps:
 103       retval.append(time.strftime('[%Y-%m-%d %I:%M:%S %Z] - '))
 104
 105     return ''.join(retval)
 106
 107   def _write(self, out, *args):
 108     """Write a message to OUT.
 109
 110     If there are multiple ARGS, they will be separated by spaces.  If
 111     there are multiple lines, they will be output one by one with the
 112     same timestamp prefix."""
 113
 114     timestamp = self._timestamp()
 115     s = ' '.join(map(str, args))
 116     lines = s.split('\n')
 117     if lines and not lines[-1]:
 118       del lines[-1]
 119
 120     self.lock.acquire()
 121     try:
 122       for s in lines:
 123         out.write('%s%s\n' % (timestamp, s,))
 124       # Ensure that log output doesn't get out-of-order with respect to
 125       # stderr output.
 126       out.flush()
 127     finally:
 128       self.lock.release()
 129
 130   def write(self, *args):
 131     """Write a message to SELF._out.
 132
 133     This is a public method to use for writing to the output log
 134     unconditionally."""
 135
 136     self._write(self._out, *args)
 137
 138   def error(self, *args):
 139     """Log a message at the ERROR level."""
 140
 141     if self.is_on(Log.ERROR):
 142       self._write(self._err, *args)
 143
 144   def warn(self, *args):
 145     """Log a message at the WARN level."""
 146
 147     if self.is_on(Log.WARN):
 148       self._write(self._out, *args)
 149
 150   def quiet(self, *args):
 151     """Log a message at the QUIET level."""
 152
 153     if self.is_on(Log.QUIET):
 154       self._write(self._out, *args)
 155
 156   def normal(self, *args):
 157     """Log a message at the NORMAL level."""
 158
 159     if self.is_on(Log.NORMAL):
 160       self._write(self._out, *args)
 161
 162   def verbose(self, *args):
 163     """Log a message at the VERBOSE level."""
 164
 165     if self.is_on(Log.VERBOSE):
 166       self._write(self._out, *args)
 167
 168   def debug(self, *args):
 169     """Log a message at the DEBUG level."""
 170
 171     if self.is_on(Log.DEBUG):
 172       self._write(self._out, *args)
 173
 174