code.delx.au - offlineimap/blob - offlineimap/threadutil.py

   1 # Copyright (C) 2002, 2003 John Goerzen
   2 # Thread support module
   3 # <jgoerzen@complete.org>
   4 #
   5 #    This program is free software; you can redistribute it and/or modify
   6 #    it under the terms of the GNU General Public License as published by
   7 #    the Free Software Foundation; either version 2 of the License, or
   8 #    (at your option) any later version.
   9 #
  10 #    This program is distributed in the hope that it will be useful,
  11 #    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 #    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 #    GNU General Public License for more details.
  14 #
  15 #    You should have received a copy of the GNU General Public License
  16 #    along with this program; if not, write to the Free Software
  17 #    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  18
  19 from threading import *
  20 from StringIO import StringIO
  21 from Queue import Queue, Empty
  22 import sys, traceback, thread, time
  23 from offlineimap.ui import UIBase       # for getglobalui()
  24
  25 profiledir = None
  26
  27 def setprofiledir(newdir):
  28     global profiledir
  29     profiledir = newdir
  30
  31 ######################################################################
  32 # General utilities
  33 ######################################################################
  34
  35 def semaphorereset(semaphore, originalstate):
  36     """Wait until the semaphore gets back to its original state -- all acquired
  37     resources released."""
  38     for i in range(originalstate):
  39         semaphore.acquire()
  40     # Now release these.
  41     for i in range(originalstate):
  42         semaphore.release()
  43
  44 def semaphorewait(semaphore):
  45     semaphore.acquire()
  46     semaphore.release()
  47
  48 def threadsreset(threadlist):
  49     for thr in threadlist:
  50         thr.join()
  51
  52 class threadlist:
  53     def __init__(self):
  54         self.lock = Lock()
  55         self.list = []
  56
  57     def add(self, thread):
  58         self.lock.acquire()
  59         try:
  60             self.list.append(thread)
  61         finally:
  62             self.lock.release()
  63
  64     def remove(self, thread):
  65         self.lock.acquire()
  66         try:
  67             self.list.remove(thread)
  68         finally:
  69             self.lock.release()
  70
  71     def pop(self):
  72         self.lock.acquire()
  73         try:
  74             if not len(self.list):
  75                 return None
  76             return self.list.pop()
  77         finally:
  78             self.lock.release()
  79
  80     def reset(self):
  81         while 1:
  82             thread = self.pop()
  83             if not thread:
  84                 return
  85             thread.join()
  86
  87
  88 ######################################################################
  89 # Exit-notify threads
  90 ######################################################################
  91
  92 exitthreads = Queue(100)
  93 inited = 0
  94
  95 def initexitnotify():
  96     """Initialize the exit notify system.  This MUST be called from the
  97     SAME THREAD that will call monitorloop BEFORE it calls monitorloop.
  98     This SHOULD be called before the main thread starts any other
  99     ExitNotifyThreads, or else it may miss the ability to catch the exit
 100     status from them!"""
 101     pass
 102
 103 def exitnotifymonitorloop(callback):
 104     """Enter an infinite "monitoring" loop.  The argument, callback,
 105     defines the function to call when an ExitNotifyThread has terminated.
 106     That function is called with a single argument -- the ExitNotifyThread
 107     that has terminated.  The monitor will not continue to monitor for
 108     other threads until the function returns, so if it intends to perform
 109     long calculations, it should start a new thread itself -- but NOT
 110     an ExitNotifyThread, or else an infinite loop may result.  Furthermore,
 111     the monitor will hold the lock all the while the other thread is waiting.
 112     """
 113     global exitthreads
 114     while 1:                            # Loop forever.
 115         try:
 116             thrd = exitthreads.get(False)
 117             callback(thrd)
 118         except Empty:
 119             time.sleep(1)
 120
 121 def threadexited(thread):
 122     """Called when a thread exits."""
 123     ui = UIBase.getglobalui()
 124     if thread.getExitCause() == 'EXCEPTION':
 125         if isinstance(thread.getExitException(), SystemExit):
 126             # Bring a SystemExit into the main thread.
 127             # Do not send it back to UI layer right now.
 128             # Maybe later send it to ui.terminate?
 129             raise SystemExit
 130         ui.threadException(thread)      # Expected to terminate
 131         sys.exit(100)                   # Just in case...
 132         os._exit(100)
 133     elif thread.getExitMessage() == 'SYNC_WITH_TIMER_TERMINATE':
 134         ui.terminate()
 135         # Just in case...
 136         sys.exit(100)
 137         os._exit(100)
 138     else:
 139         ui.threadExited(thread)
 140
 141 class ExitNotifyThread(Thread):
 142     """This class is designed to alert a "monitor" to the fact that a thread has
 143     exited and to provide for the ability for it to find out why."""
 144     def run(self):
 145         global exitthreads, profiledir
 146         self.threadid = thread.get_ident()
 147         try:
 148             if not profiledir:          # normal case
 149                 Thread.run(self)
 150             else:
 151                 import profile
 152                 prof = profile.Profile()
 153                 try:
 154                     prof = prof.runctx("Thread.run(self)", globals(), locals())
 155                 except SystemExit:
 156                     pass
 157                 prof.dump_stats( \
 158                             profiledir + "/" + str(self.threadid) + "_" + \
 159                             self.getName() + ".prof")
 160         except:
 161             self.setExitCause('EXCEPTION')
 162             if sys:
 163                 self.setExitException(sys.exc_info()[1])
 164                 sbuf = StringIO()
 165                 traceback.print_exc(file = sbuf)
 166                 self.setExitStackTrace(sbuf.getvalue())
 167         else:
 168             self.setExitCause('NORMAL')
 169         if not hasattr(self, 'exitmessage'):
 170             self.setExitMessage(None)
 171
 172         if exitthreads:
 173             exitthreads.put(self, True)
 174
 175     def setExitCause(self, cause):
 176         self.exitcause = cause
 177     def getExitCause(self):
 178         """Returns the cause of the exit, one of:
 179         'EXCEPTION' -- the thread aborted because of an exception
 180         'NORMAL' -- normal termination."""
 181         return self.exitcause
 182     def setExitException(self, exc):
 183         self.exitexception = exc
 184     def getExitException(self):
 185         """If getExitCause() is 'EXCEPTION', holds the value from
 186         sys.exc_info()[1] for this exception."""
 187         return self.exitexception
 188     def setExitStackTrace(self, st):
 189         self.exitstacktrace = st
 190     def getExitStackTrace(self):
 191         """If getExitCause() is 'EXCEPTION', returns a string representing
 192         the stack trace for this exception."""
 193         return self.exitstacktrace
 194     def setExitMessage(self, msg):
 195         """Sets the exit message to be fetched by a subsequent call to
 196         getExitMessage.  This message may be any object or type except
 197         None."""
 198         self.exitmessage = msg
 199     def getExitMessage(self):
 200         """For any exit cause, returns the message previously set by
 201         a call to setExitMessage(), or None if there was no such message
 202         set."""
 203         return self.exitmessage
 204
 205
 206 ######################################################################
 207 # Instance-limited threads
 208 ######################################################################
 209
 210 instancelimitedsems = {}
 211 instancelimitedlock = Lock()
 212
 213 def initInstanceLimit(instancename, instancemax):
 214     """Initialize the instance-limited thread implementation to permit
 215     up to intancemax threads with the given instancename."""
 216     instancelimitedlock.acquire()
 217     if not instancelimitedsems.has_key(instancename):
 218         instancelimitedsems[instancename] = BoundedSemaphore(instancemax)
 219     instancelimitedlock.release()
 220
 221 class InstanceLimitedThread(ExitNotifyThread):
 222     def __init__(self, instancename, *args, **kwargs):
 223         self.instancename = instancename
 224
 225         apply(ExitNotifyThread.__init__, (self,) + args, kwargs)
 226
 227     def start(self):
 228         instancelimitedsems[self.instancename].acquire()
 229         ExitNotifyThread.start(self)
 230
 231     def run(self):
 232         try:
 233             ExitNotifyThread.run(self)
 234         finally:
 235             if instancelimitedsems and instancelimitedsems[self.instancename]:
 236                 instancelimitedsems[self.instancename].release()
 237
 238
 239 ######################################################################
 240 # Multi-lock -- capable of handling a single thread requesting a lock
 241 # multiple times
 242 ######################################################################
 243
 244 class MultiLock:
 245     def __init__(self):
 246         self.lock = Lock()
 247         self.statuslock = Lock()
 248         self.locksheld = {}
 249
 250     def acquire(self):
 251         """Obtain a lock.  Provides nice support for a single
 252         thread trying to lock it several times -- as may be the case
 253         if one I/O-using object calls others, while wanting to make it all
 254         an atomic operation.  Keeps a "lock request count" for the current
 255         thread, and acquires the lock when it goes above zero, releases when
 256         it goes below one.
 257
 258         This call is always blocking."""
 259
 260         # First, check to see if this thread already has a lock.
 261         # If so, increment the lock count and just return.
 262         self.statuslock.acquire()
 263         try:
 264             threadid = thread.get_ident()
 265
 266             if threadid in self.locksheld:
 267                 self.locksheld[threadid] += 1
 268                 return
 269             else:
 270                 # This is safe because it is a per-thread structure
 271                 self.locksheld[threadid] = 1
 272         finally:
 273             self.statuslock.release()
 274         self.lock.acquire()
 275
 276     def release(self):
 277         self.statuslock.acquire()
 278         try:
 279             threadid = thread.get_ident()
 280             if self.locksheld[threadid] > 1:
 281                 self.locksheld[threadid] -= 1
 282                 return
 283             else:
 284                 del self.locksheld[threadid]
 285                 self.lock.release()
 286         finally:
 287             self.statuslock.release()
 288
 289