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             print "exitnotifymonitorloop: Got thread\n"
 118             callback(thrd)
 119             print "exitnotifymonitorloop: callback done\n"
 120             exitthreads.task_done()
 121         except Empty:
 122             time.sleep(1)
 123
 124 def threadexited(thread):
 125     """Called when a thread exits."""
 126     ui = UIBase.getglobalui()
 127     if thread.getExitCause() == 'EXCEPTION':
 128         if isinstance(thread.getExitException(), SystemExit):
 129             # Bring a SystemExit into the main thread.
 130             # Do not send it back to UI layer right now.
 131             # Maybe later send it to ui.terminate?
 132             raise SystemExit
 133         ui.threadException(thread)      # Expected to terminate
 134         sys.exit(100)                   # Just in case...
 135         os._exit(100)
 136     elif thread.getExitMessage() == 'SYNC_WITH_TIMER_TERMINATE':
 137         ui.terminate()
 138         # Just in case...
 139         sys.exit(100)
 140         os._exit(100)
 141     else:
 142         ui.threadExited(thread)
 143
 144 class ExitNotifyThread(Thread):
 145     """This class is designed to alert a "monitor" to the fact that a thread has
 146     exited and to provide for the ability for it to find out why."""
 147     def run(self):
 148         global exitthreads, profiledir
 149         self.threadid = thread.get_ident()
 150         try:
 151             if not profiledir:          # normal case
 152                 Thread.run(self)
 153             else:
 154                 import profile
 155                 prof = profile.Profile()
 156                 try:
 157                     prof = prof.runctx("Thread.run(self)", globals(), locals())
 158                 except SystemExit:
 159                     pass
 160                 prof.dump_stats( \
 161                             profiledir + "/" + str(self.threadid) + "_" + \
 162                             self.getName() + ".prof")
 163         except:
 164             self.setExitCause('EXCEPTION')
 165             self.setExitException(sys.exc_info()[1])
 166             sbuf = StringIO()
 167             traceback.print_exc(file = sbuf)
 168             self.setExitStackTrace(sbuf.getvalue())
 169         else:
 170             self.setExitCause('NORMAL')
 171         if not hasattr(self, 'exitmessage'):
 172             self.setExitMessage(None)
 173
 174         exitthreads.put(self, True)
 175
 176     def setExitCause(self, cause):
 177         self.exitcause = cause
 178     def getExitCause(self):
 179         """Returns the cause of the exit, one of:
 180         'EXCEPTION' -- the thread aborted because of an exception
 181         'NORMAL' -- normal termination."""
 182         return self.exitcause
 183     def setExitException(self, exc):
 184         self.exitexception = exc
 185     def getExitException(self):
 186         """If getExitCause() is 'EXCEPTION', holds the value from
 187         sys.exc_info()[1] for this exception."""
 188         return self.exitexception
 189     def setExitStackTrace(self, st):
 190         self.exitstacktrace = st
 191     def getExitStackTrace(self):
 192         """If getExitCause() is 'EXCEPTION', returns a string representing
 193         the stack trace for this exception."""
 194         return self.exitstacktrace
 195     def setExitMessage(self, msg):
 196         """Sets the exit message to be fetched by a subsequent call to
 197         getExitMessage.  This message may be any object or type except
 198         None."""
 199         self.exitmessage = msg
 200     def getExitMessage(self):
 201         """For any exit cause, returns the message previously set by
 202         a call to setExitMessage(), or None if there was no such message
 203         set."""
 204         return self.exitmessage
 205
 206
 207 ######################################################################
 208 # Instance-limited threads
 209 ######################################################################
 210
 211 instancelimitedsems = {}
 212 instancelimitedlock = Lock()
 213
 214 def initInstanceLimit(instancename, instancemax):
 215     """Initialize the instance-limited thread implementation to permit
 216     up to intancemax threads with the given instancename."""
 217     instancelimitedlock.acquire()
 218     if not instancelimitedsems.has_key(instancename):
 219         instancelimitedsems[instancename] = BoundedSemaphore(instancemax)
 220     instancelimitedlock.release()
 221
 222 class InstanceLimitedThread(ExitNotifyThread):
 223     def __init__(self, instancename, *args, **kwargs):
 224         self.instancename = instancename
 225
 226         apply(ExitNotifyThread.__init__, (self,) + args, kwargs)
 227
 228     def start(self):
 229         instancelimitedsems[self.instancename].acquire()
 230         ExitNotifyThread.start(self)
 231
 232     def run(self):
 233         try:
 234             ExitNotifyThread.run(self)
 235         finally:
 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