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.  We also
  53     # write these to stderr so that other output (e.g., dumpfiles) can
  54     # be written to stdout without being contaminated with progress
  55     # messages:
  56     self._out = sys.stderr
  57
  58     # Lock to serialize writes to the log:
  59     self.lock = threading.Lock()
  60
  61   def increase_verbosity(self):
  62     self.lock.acquire()
  63     try:
  64       self.log_level = min(self.log_level + 1, _Log.DEBUG)
  65     finally:
  66       self.lock.release()
  67
  68   def decrease_verbosity(self):
  69     self.lock.acquire()
  70     try:
  71       self.log_level = max(self.log_level - 1, _Log.ERROR)
  72     finally:
  73       self.lock.release()
  74
  75   def is_on(self, level):
  76     """Return True iff messages at the specified LEVEL are currently on.
  77
  78     LEVEL should be one of the constants _Log.WARN, _Log.QUIET, etc."""
  79
  80     return self.log_level >= level
  81
  82   def _timestamp(self):
  83     """Return a timestamp if needed, as a string with a trailing space."""
  84
  85     retval = []
  86
  87     if self.log_level >= _Log.DEBUG:
  88       retval.append('%f: ' % (time.time() - self.start_time,))
  89
  90     return ''.join(retval)
  91
  92   def _write(self, out, *args):
  93     """Write a message to OUT.
  94
  95     If there are multiple ARGS, they will be separated by spaces.  If
  96     there are multiple lines, they will be output one by one with the
  97     same timestamp prefix."""
  98
  99     timestamp = self._timestamp()
 100     s = ' '.join(map(str, args))
 101     lines = s.split('\n')
 102     if lines and not lines[-1]:
 103       del lines[-1]
 104
 105     self.lock.acquire()
 106     try:
 107       for s in lines:
 108         out.write('%s%s\n' % (timestamp, s,))
 109       # Ensure that log output doesn't get out-of-order with respect to
 110       # stderr output.
 111       out.flush()
 112     finally:
 113       self.lock.release()
 114
 115   def write(self, *args):
 116     """Write a message to SELF._out.
 117
 118     This is a public method to use for writing to the output log
 119     unconditionally."""
 120
 121     self._write(self._out, *args)
 122
 123   def error(self, *args):
 124     """Log a message at the ERROR level."""
 125
 126     if self.is_on(_Log.ERROR):
 127       self._write(self._err, *args)
 128
 129   def warn(self, *args):
 130     """Log a message at the WARN level."""
 131
 132     if self.is_on(_Log.WARN):
 133       self._write(self._out, *args)
 134
 135   def quiet(self, *args):
 136     """Log a message at the QUIET level."""
 137
 138     if self.is_on(_Log.QUIET):
 139       self._write(self._out, *args)
 140
 141   def normal(self, *args):
 142     """Log a message at the NORMAL level."""
 143
 144     if self.is_on(_Log.NORMAL):
 145       self._write(self._out, *args)
 146
 147   def verbose(self, *args):
 148     """Log a message at the VERBOSE level."""
 149
 150     if self.is_on(_Log.VERBOSE):
 151       self._write(self._out, *args)
 152
 153   def debug(self, *args):
 154     """Log a message at the DEBUG level."""
 155
 156     if self.is_on(_Log.DEBUG):
 157       self._write(self._out, *args)
 158
 159
 160 # Create an instance that everybody can use:
 161 logger = _Log()
 162
 163