Lib/logging/config.py

   1 # Copyright 2001-2005 by Vinay Sajip. All Rights Reserved.
   2 #
   3 # Permission to use, copy, modify, and distribute this software and its
   4 # documentation for any purpose and without fee is hereby granted,
   5 # provided that the above copyright notice appear in all copies and that
   6 # both that copyright notice and this permission notice appear in
   7 # supporting documentation, and that the name of Vinay Sajip
   8 # not be used in advertising or publicity pertaining to distribution
   9 # of the software without specific, written prior permission.
  10 # VINAY SAJIP DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
  11 # ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
  12 # VINAY SAJIP BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
  13 # ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
  14 # IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  15 # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16
  17 """
  18 Configuration functions for the logging package for Python. The core package
  19 is based on PEP 282 and comments thereto in comp.lang.python, and influenced
  20 by Apache's log4j system.
  21
  22 Should work under Python versions >= 1.5.2, except that source line
  23 information is not available unless 'sys._getframe()' is.
  24
  25 Copyright (C) 2001-2004 Vinay Sajip. All Rights Reserved.
  26
  27 To use, simply 'import logging' and log away!
  28 """
  29
  30 import sys, logging, logging.handlers, string, socket, struct, os, traceback
  31
  32 try:
  33     import thread
  34     import threading
  35 except ImportError:
  36     thread = None
  37
  38 from SocketServer import ThreadingTCPServer, StreamRequestHandler
  39
  40
  41 DEFAULT_LOGGING_CONFIG_PORT = 9030
  42
  43 if sys.platform == "win32":
  44     RESET_ERROR = 10054   #WSAECONNRESET
  45 else:
  46     RESET_ERROR = 104     #ECONNRESET
  47
  48 #
  49 #   The following code implements a socket listener for on-the-fly
  50 #   reconfiguration of logging.
  51 #
  52 #   _listener holds the server object doing the listening
  53 _listener = None
  54
  55 def fileConfig(fname, defaults=None):
  56     """
  57     Read the logging configuration from a ConfigParser-format file.
  58
  59     This can be called several times from an application, allowing an end user
  60     the ability to select from various pre-canned configurations (if the
  61     developer provides a mechanism to present the choices and load the chosen
  62     configuration).
  63     In versions of ConfigParser which have the readfp method [typically
  64     shipped in 2.x versions of Python], you can pass in a file-like object
  65     rather than a filename, in which case the file-like object will be read
  66     using readfp.
  67     """
  68     import ConfigParser
  69
  70     cp = ConfigParser.ConfigParser(defaults)
  71     if hasattr(cp, 'readfp') and hasattr(fname, 'readline'):
  72         cp.readfp(fname)
  73     else:
  74         cp.read(fname)
  75
  76     formatters = _create_formatters(cp)
  77
  78     # critical section
  79     logging._acquireLock()
  80     try:
  81         logging._handlers.clear()
  82         del logging._handlerList[:]
  83         # Handlers add themselves to logging._handlers
  84         handlers = _install_handlers(cp, formatters)
  85         _install_loggers(cp, handlers)
  86     finally:
  87         logging._releaseLock()
  88
  89
  90 def _resolve(name):
  91     """Resolve a dotted name to a global object."""
  92     name = string.split(name, '.')
  93     used = name.pop(0)
  94     found = __import__(used)
  95     for n in name:
  96         used = used + '.' + n
  97         try:
  98             found = getattr(found, n)
  99         except AttributeError:
 100             __import__(used)
 101             found = getattr(found, n)
 102     return found
 103
 104
 105 def _create_formatters(cp):
 106     """Create and return formatters"""
 107     flist = cp.get("formatters", "keys")
 108     if not len(flist):
 109         return {}
 110     flist = string.split(flist, ",")
 111     formatters = {}
 112     for form in flist:
 113         sectname = "formatter_%s" % form
 114         opts = cp.options(sectname)
 115         if "format" in opts:
 116             fs = cp.get(sectname, "format", 1)
 117         else:
 118             fs = None
 119         if "datefmt" in opts:
 120             dfs = cp.get(sectname, "datefmt", 1)
 121         else:
 122             dfs = None
 123         c = logging.Formatter
 124         if "class" in opts:
 125             class_name = cp.get(sectname, "class")
 126             if class_name:
 127                 c = _resolve(class_name)
 128         f = c(fs, dfs)
 129         formatters[form] = f
 130     return formatters
 131
 132
 133 def _install_handlers(cp, formatters):
 134     """Install and return handlers"""
 135     hlist = cp.get("handlers", "keys")
 136     if not len(hlist):
 137         return {}
 138     hlist = string.split(hlist, ",")
 139     handlers = {}
 140     fixups = [] #for inter-handler references
 141     for hand in hlist:
 142         sectname = "handler_%s" % hand
 143         klass = cp.get(sectname, "class")
 144         opts = cp.options(sectname)
 145         if "formatter" in opts:
 146             fmt = cp.get(sectname, "formatter")
 147         else:
 148             fmt = ""
 149         klass = eval(klass, vars(logging))
 150         args = cp.get(sectname, "args")
 151         args = eval(args, vars(logging))
 152         h = apply(klass, args)
 153         if "level" in opts:
 154             level = cp.get(sectname, "level")
 155             h.setLevel(logging._levelNames[level])
 156         if len(fmt):
 157             h.setFormatter(formatters[fmt])
 158         #temporary hack for FileHandler and MemoryHandler.
 159         if klass == logging.handlers.MemoryHandler:
 160             if "target" in opts:
 161                 target = cp.get(sectname,"target")
 162             else:
 163                 target = ""
 164             if len(target): #the target handler may not be loaded yet, so keep for later...
 165                 fixups.append((h, target))
 166         handlers[hand] = h
 167     #now all handlers are loaded, fixup inter-handler references...
 168     for h, t in fixups:
 169         h.setTarget(handlers[t])
 170     return handlers
 171
 172
 173 def _install_loggers(cp, handlers):
 174     """Create and install loggers"""
 175
 176     # configure the root first
 177     llist = cp.get("loggers", "keys")
 178     llist = string.split(llist, ",")
 179     llist.remove("root")
 180     sectname = "logger_root"
 181     root = logging.root
 182     log = root
 183     opts = cp.options(sectname)
 184     if "level" in opts:
 185         level = cp.get(sectname, "level")
 186         log.setLevel(logging._levelNames[level])
 187     for h in root.handlers[:]:
 188         root.removeHandler(h)
 189     hlist = cp.get(sectname, "handlers")
 190     if len(hlist):
 191         hlist = string.split(hlist, ",")
 192         for hand in hlist:
 193             log.addHandler(handlers[hand])
 194
 195     #and now the others...
 196     #we don't want to lose the existing loggers,
 197     #since other threads may have pointers to them.
 198     #existing is set to contain all existing loggers,
 199     #and as we go through the new configuration we
 200     #remove any which are configured. At the end,
 201     #what's left in existing is the set of loggers
 202     #which were in the previous configuration but
 203     #which are not in the new configuration.
 204     existing = root.manager.loggerDict.keys()
 205     #now set up the new ones...
 206     for log in llist:
 207         sectname = "logger_%s" % log
 208         qn = cp.get(sectname, "qualname")
 209         opts = cp.options(sectname)
 210         if "propagate" in opts:
 211             propagate = cp.getint(sectname, "propagate")
 212         else:
 213             propagate = 1
 214         logger = logging.getLogger(qn)
 215         if qn in existing:
 216             existing.remove(qn)
 217         if "level" in opts:
 218             level = cp.get(sectname, "level")
 219             logger.setLevel(logging._levelNames[level])
 220         for h in logger.handlers[:]:
 221             logger.removeHandler(h)
 222         logger.propagate = propagate
 223         logger.disabled = 0
 224         hlist = cp.get(sectname, "handlers")
 225         if len(hlist):
 226             hlist = string.split(hlist, ",")
 227             for hand in hlist:
 228                 logger.addHandler(handlers[hand])
 229
 230     #Disable any old loggers. There's no point deleting
 231     #them as other threads may continue to hold references
 232     #and by disabling them, you stop them doing any logging.
 233     for log in existing:
 234         root.manager.loggerDict[log].disabled = 1
 235
 236
 237 def listen(port=DEFAULT_LOGGING_CONFIG_PORT):
 238     """
 239     Start up a socket server on the specified port, and listen for new
 240     configurations.
 241
 242     These will be sent as a file suitable for processing by fileConfig().
 243     Returns a Thread object on which you can call start() to start the server,
 244     and which you can join() when appropriate. To stop the server, call
 245     stopListening().
 246     """
 247     if not thread:
 248         raise NotImplementedError, "listen() needs threading to work"
 249
 250     class ConfigStreamHandler(StreamRequestHandler):
 251         """
 252         Handler for a logging configuration request.
 253
 254         It expects a completely new logging configuration and uses fileConfig
 255         to install it.
 256         """
 257         def handle(self):
 258             """
 259             Handle a request.
 260
 261             Each request is expected to be a 4-byte length, packed using
 262             struct.pack(">L", n), followed by the config file.
 263             Uses fileConfig() to do the grunt work.
 264             """
 265             import tempfile
 266             try:
 267                 conn = self.connection
 268                 chunk = conn.recv(4)
 269                 if len(chunk) == 4:
 270                     slen = struct.unpack(">L", chunk)[0]
 271                     chunk = self.connection.recv(slen)
 272                     while len(chunk) < slen:
 273                         chunk = chunk + conn.recv(slen - len(chunk))
 274                     #Apply new configuration. We'd like to be able to
 275                     #create a StringIO and pass that in, but unfortunately
 276                     #1.5.2 ConfigParser does not support reading file
 277                     #objects, only actual files. So we create a temporary
 278                     #file and remove it later.
 279                     file = tempfile.mktemp(".ini")
 280                     f = open(file, "w")
 281                     f.write(chunk)
 282                     f.close()
 283                     try:
 284                         fileConfig(file)
 285                     except (KeyboardInterrupt, SystemExit):
 286                         raise
 287                     except:
 288                         traceback.print_exc()
 289                     os.remove(file)
 290             except socket.error, e:
 291                 if type(e.args) != types.TupleType:
 292                     raise
 293                 else:
 294                     errcode = e.args[0]
 295                     if errcode != RESET_ERROR:
 296                         raise
 297
 298     class ConfigSocketReceiver(ThreadingTCPServer):
 299         """
 300         A simple TCP socket-based logging config receiver.
 301         """
 302
 303         allow_reuse_address = 1
 304
 305         def __init__(self, host='localhost', port=DEFAULT_LOGGING_CONFIG_PORT,
 306                      handler=None):
 307             ThreadingTCPServer.__init__(self, (host, port), handler)
 308             logging._acquireLock()
 309             self.abort = 0
 310             logging._releaseLock()
 311             self.timeout = 1
 312
 313         def serve_until_stopped(self):
 314             import select
 315             abort = 0
 316             while not abort:
 317                 rd, wr, ex = select.select([self.socket.fileno()],
 318                                            [], [],
 319                                            self.timeout)
 320                 if rd:
 321                     self.handle_request()
 322                 logging._acquireLock()
 323                 abort = self.abort
 324                 logging._releaseLock()
 325
 326     def serve(rcvr, hdlr, port):
 327         server = rcvr(port=port, handler=hdlr)
 328         global _listener
 329         logging._acquireLock()
 330         _listener = server
 331         logging._releaseLock()
 332         server.serve_until_stopped()
 333
 334     return threading.Thread(target=serve,
 335                             args=(ConfigSocketReceiver,
 336                                   ConfigStreamHandler, port))
 337
 338 def stopListening():
 339     """
 340     Stop the listening server which was created with a call to listen().
 341     """
 342     global _listener
 343     if _listener:
 344         logging._acquireLock()
 345         _listener.abort = 1
 346         _listener = None
 347         logging._releaseLock()