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 import sys, traceback, thread
  22 from offlineimap.ui import UIBase       # for getglobalui()
  23
  24 profiledir = None
  25
  26 def setprofiledir(newdir):
  27     global profiledir
  28     profiledir = newdir
  29
  30 ######################################################################
  31 # General utilities
  32 ######################################################################
  33
  34 def semaphorereset(semaphore, originalstate):
  35     """Wait until the semaphore gets back to its original state -- all acquired
  36     resources released."""
  37     for i in range(originalstate):
  38         semaphore.acquire()
  39     # Now release these.
  40     for i in range(originalstate):
  41         semaphore.release()
  42
  43 def semaphorewait(semaphore):
  44     semaphore.acquire()
  45     semaphore.release()
  46
  47 def threadsreset(threadlist):
  48     for thr in threadlist:
  49         thr.join()
  50
  51 class threadlist:
  52     def __init__(self):
  53         self.lock = Lock()
  54         self.list = []
  55
  56     def add(self, thread):
  57         self.lock.acquire()
  58         try:
  59             self.list.append(thread)
  60         finally:
  61             self.lock.release()
  62
  63     def remove(self, thread):
  64         self.lock.acquire()
  65         try:
  66             self.list.remove(thread)
  67         finally:
  68             self.lock.release()
  69
  70     def pop(self):
  71         self.lock.acquire()
  72         try:
  73             if not len(self.list):
  74                 return None
  75             return self.list.pop()
  76         finally:
  77             self.lock.release()
  78
  79     def reset(self):
  80         while 1:
  81             thread = self.pop()
  82             if not thread:
  83                 return
  84             thread.join()
  85
  86
  87 ######################################################################
  88 # Exit-notify threads
  89 ######################################################################
  90
  91 exitcondition = Condition(Lock())
  92 exitthreads = []
  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 exitcondition, exitthreads
 114     while 1:                            # Loop forever.
 115         exitcondition.acquire()
 116         try:
 117             while not len(exitthreads):
 118                 exitcondition.wait(1)
 119
 120             while len(exitthreads):
 121                 callback(exitthreads.pop(0)) # Pull off in order added!
 122         finally:
 123             exitcondition.release()
 124
 125 def threadexited(thread):
 126     """Called when a thread exits."""
 127     ui = UIBase.getglobalui()
 128     if thread.getExitCause() == 'EXCEPTION':
 129         if isinstance(thread.getExitException(), SystemExit):
 130             # Bring a SystemExit into the main thread.
 131             # Do not send it back to UI layer right now.
 132             # Maybe later send it to ui.terminate?
 133             raise SystemExit
 134         ui.threadException(thread)      # Expected to terminate
 135         sys.exit(100)                   # Just in case...
 136         os._exit(100)
 137     elif thread.getExitMessage() == 'SYNC_WITH_TIMER_TERMINATE':
 138         ui.terminate()
 139         # Just in case...
 140         sys.exit(100)
 141         os._exit(100)
 142     else:
 143         ui.threadExited(thread)
 144
 145 class ExitNotifyThread(Thread):
 146     """This class is designed to alert a "monitor" to the fact that a thread has
 147     exited and to provide for the ability for it to find out why."""
 148     def run(self):
 149         global exitcondition, exitthreads, profiledir
 150         self.threadid = thread.get_ident()
 151         try:
 152             if not profiledir:          # normal case
 153                 Thread.run(self)
 154             else:
 155                 import profile
 156                 prof = profile.Profile()
 157                 try:
 158                     prof = prof.runctx("Thread.run(self)", globals(), locals())
 159                 except SystemExit:
 160                     pass
 161                 prof.dump_stats( \
 162                             profiledir + "/" + str(self.threadid) + "_" + \
 163                             self.getName() + ".prof")
 164         except:
 165             self.setExitCause('EXCEPTION')
 166             self.setExitException(sys.exc_info()[1])
 167             sbuf = StringIO()
 168             traceback.print_exc(file = sbuf)
 169             self.setExitStackTrace(sbuf.getvalue())
 170         else:
 171             self.setExitCause('NORMAL')
 172         if not hasattr(self, 'exitmessage'):
 173             self.setExitMessage(None)
 174         exitcondition.acquire()
 175         exitthreads.append(self)
 176         exitcondition.notify()
 177         exitcondition.release()
 178
 179     def setExitCause(self, cause):
 180         self.exitcause = cause
 181     def getExitCause(self):
 182         """Returns the cause of the exit, one of:
 183         'EXCEPTION' -- the thread aborted because of an exception
 184         'NORMAL' -- normal termination."""
 185         return self.exitcause
 186     def setExitException(self, exc):
 187         self.exitexception = exc
 188     def getExitException(self):
 189         """If getExitCause() is 'EXCEPTION', holds the value from
 190         sys.exc_info()[1] for this exception."""
 191         return self.exitexception
 192     def setExitStackTrace(self, st):
 193         self.exitstacktrace = st
 194     def getExitStackTrace(self):
 195         """If getExitCause() is 'EXCEPTION', returns a string representing
 196         the stack trace for this exception."""
 197         return self.exitstacktrace
 198     def setExitMessage(self, msg):
 199         """Sets the exit message to be fetched by a subsequent call to
 200         getExitMessage.  This message may be any object or type except
 201         None."""
 202         self.exitmessage = msg
 203     def getExitMessage(self):
 204         """For any exit cause, returns the message previously set by
 205         a call to setExitMessage(), or None if there was no such message
 206         set."""
 207         return self.exitmessage
 208
 209
 210 ######################################################################
 211 # Instance-limited threads
 212 ######################################################################
 213
 214 instancelimitedsems = {}
 215 instancelimitedlock = Lock()
 216
 217 def initInstanceLimit(instancename, instancemax):
 218     """Initialize the instance-limited thread implementation to permit
 219     up to intancemax threads with the given instancename."""
 220     instancelimitedlock.acquire()
 221     if not instancelimitedsems.has_key(instancename):
 222         instancelimitedsems[instancename] = BoundedSemaphore(instancemax)
 223     instancelimitedlock.release()
 224
 225 class InstanceLimitedThread(ExitNotifyThread):
 226     def __init__(self, instancename, *args, **kwargs):
 227         self.instancename = instancename
 228
 229         apply(ExitNotifyThread.__init__, (self,) + args, kwargs)
 230
 231     def start(self):
 232         instancelimitedsems[self.instancename].acquire()
 233         ExitNotifyThread.start(self)
 234
 235     def run(self):
 236         try:
 237             ExitNotifyThread.run(self)
 238         finally:
 239             instancelimitedsems[self.instancename].release()
 240
 241
 242 ######################################################################
 243 # Multi-lock -- capable of handling a single thread requesting a lock
 244 # multiple times
 245 ######################################################################
 246
 247 class MultiLock:
 248     def __init__(self):
 249         self.lock = Lock()
 250         self.statuslock = Lock()
 251         self.locksheld = {}
 252
 253     def acquire(self):
 254         """Obtain a lock.  Provides nice support for a single
 255         thread trying to lock it several times -- as may be the case
 256         if one I/O-using object calls others, while wanting to make it all
 257         an atomic operation.  Keeps a "lock request count" for the current
 258         thread, and acquires the lock when it goes above zero, releases when
 259         it goes below one.
 260
 261         This call is always blocking."""
 262
 263         # First, check to see if this thread already has a lock.
 264         # If so, increment the lock count and just return.
 265         self.statuslock.acquire()
 266         try:
 267             threadid = thread.get_ident()
 268
 269             if threadid in self.locksheld:
 270                 self.locksheld[threadid] += 1
 271                 return
 272             else:
 273                 # This is safe because it is a per-thread structure
 274                 self.locksheld[threadid] = 1
 275         finally:
 276             self.statuslock.release()
 277         self.lock.acquire()
 278
 279     def release(self):
 280         self.statuslock.acquire()
 281         try:
 282             threadid = thread.get_ident()
 283             if self.locksheld[threadid] > 1:
 284                 self.locksheld[threadid] -= 1
 285                 return
 286             else:
 287                 del self.locksheld[threadid]
 288                 self.lock.release()
 289         finally:
 290             self.statuslock.release()
 291
 292