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
  22 import sys, traceback, thread
  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(5)
  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         callback(exitthreads.get(True))
 116         exitthreads.task_done()
 117
 118 def threadexited(thread):
 119     """Called when a thread exits."""
 120     ui = UIBase.getglobalui()
 121     if thread.getExitCause() == 'EXCEPTION':
 122         if isinstance(thread.getExitException(), SystemExit):
 123             # Bring a SystemExit into the main thread.
 124             # Do not send it back to UI layer right now.
 125             # Maybe later send it to ui.terminate?
 126             raise SystemExit
 127         ui.threadException(thread)      # Expected to terminate
 128         sys.exit(100)                   # Just in case...
 129         os._exit(100)
 130     elif thread.getExitMessage() == 'SYNC_WITH_TIMER_TERMINATE':
 131         ui.terminate()
 132         # Just in case...
 133         sys.exit(100)
 134         os._exit(100)
 135     else:
 136         ui.threadExited(thread)
 137
 138 class ExitNotifyThread(Thread):
 139     """This class is designed to alert a "monitor" to the fact that a thread has
 140     exited and to provide for the ability for it to find out why."""
 141     def run(self):
 142         global exitthreads, profiledir
 143         self.threadid = thread.get_ident()
 144         try:
 145             if not profiledir:          # normal case
 146                 Thread.run(self)
 147             else:
 148                 import profile
 149                 prof = profile.Profile()
 150                 try:
 151                     prof = prof.runctx("Thread.run(self)", globals(), locals())
 152                 except SystemExit:
 153                     pass
 154                 prof.dump_stats( \
 155                             profiledir + "/" + str(self.threadid) + "_" + \
 156                             self.getName() + ".prof")
 157         except:
 158             self.setExitCause('EXCEPTION')
 159             self.setExitException(sys.exc_info()[1])
 160             sbuf = StringIO()
 161             traceback.print_exc(file = sbuf)
 162             self.setExitStackTrace(sbuf.getvalue())
 163         else:
 164             self.setExitCause('NORMAL')
 165         if not hasattr(self, 'exitmessage'):
 166             self.setExitMessage(None)
 167
 168         exitthreads.put(self, True)
 169
 170     def setExitCause(self, cause):
 171         self.exitcause = cause
 172     def getExitCause(self):
 173         """Returns the cause of the exit, one of:
 174         'EXCEPTION' -- the thread aborted because of an exception
 175         'NORMAL' -- normal termination."""
 176         return self.exitcause
 177     def setExitException(self, exc):
 178         self.exitexception = exc
 179     def getExitException(self):
 180         """If getExitCause() is 'EXCEPTION', holds the value from
 181         sys.exc_info()[1] for this exception."""
 182         return self.exitexception
 183     def setExitStackTrace(self, st):
 184         self.exitstacktrace = st
 185     def getExitStackTrace(self):
 186         """If getExitCause() is 'EXCEPTION', returns a string representing
 187         the stack trace for this exception."""
 188         return self.exitstacktrace
 189     def setExitMessage(self, msg):
 190         """Sets the exit message to be fetched by a subsequent call to
 191         getExitMessage.  This message may be any object or type except
 192         None."""
 193         self.exitmessage = msg
 194     def getExitMessage(self):
 195         """For any exit cause, returns the message previously set by
 196         a call to setExitMessage(), or None if there was no such message
 197         set."""
 198         return self.exitmessage
 199
 200
 201 ######################################################################
 202 # Instance-limited threads
 203 ######################################################################
 204
 205 instancelimitedsems = {}
 206 instancelimitedlock = Lock()
 207
 208 def initInstanceLimit(instancename, instancemax):
 209     """Initialize the instance-limited thread implementation to permit
 210     up to intancemax threads with the given instancename."""
 211     instancelimitedlock.acquire()
 212     if not instancelimitedsems.has_key(instancename):
 213         instancelimitedsems[instancename] = BoundedSemaphore(instancemax)
 214     instancelimitedlock.release()
 215
 216 class InstanceLimitedThread(ExitNotifyThread):
 217     def __init__(self, instancename, *args, **kwargs):
 218         self.instancename = instancename
 219
 220         apply(ExitNotifyThread.__init__, (self,) + args, kwargs)
 221
 222     def start(self):
 223         instancelimitedsems[self.instancename].acquire()
 224         ExitNotifyThread.start(self)
 225
 226     def run(self):
 227         try:
 228             ExitNotifyThread.run(self)
 229         finally:
 230             instancelimitedsems[self.instancename].release()
 231
 232
 233 ######################################################################
 234 # Multi-lock -- capable of handling a single thread requesting a lock
 235 # multiple times
 236 ######################################################################
 237
 238 class MultiLock:
 239     def __init__(self):
 240         self.lock = Lock()
 241         self.statuslock = Lock()
 242         self.locksheld = {}
 243
 244     def acquire(self):
 245         """Obtain a lock.  Provides nice support for a single
 246         thread trying to lock it several times -- as may be the case
 247         if one I/O-using object calls others, while wanting to make it all
 248         an atomic operation.  Keeps a "lock request count" for the current
 249         thread, and acquires the lock when it goes above zero, releases when
 250         it goes below one.
 251
 252         This call is always blocking."""
 253
 254         # First, check to see if this thread already has a lock.
 255         # If so, increment the lock count and just return.
 256         self.statuslock.acquire()
 257         try:
 258             threadid = thread.get_ident()
 259
 260             if threadid in self.locksheld:
 261                 self.locksheld[threadid] += 1
 262                 return
 263             else:
 264                 # This is safe because it is a per-thread structure
 265                 self.locksheld[threadid] = 1
 266         finally:
 267             self.statuslock.release()
 268         self.lock.acquire()
 269
 270     def release(self):
 271         self.statuslock.acquire()
 272         try:
 273             threadid = thread.get_ident()
 274             if self.locksheld[threadid] > 1:
 275                 self.locksheld[threadid] -= 1
 276                 return
 277             else:
 278                 del self.locksheld[threadid]
 279                 self.lock.release()
 280         finally:
 281             self.statuslock.release()
 282
 283