9c761cddad
More locking updates. Introduced a new MultiLock to threadutil. This lock will let a single thread acquire the same lock more than once, keeping track of how many times this happens, and will release the actual lock only when the lock's lock count gets back to zero. By using MultiLock, various functions in Curses.py and Blinkenlights.py no longer need to pass around to other functions a parameter indicating whether or not a lock should be obtained. This was a large cause of complexity and errors, which is now eliminated. Everything seems to be working properly wrt locking at this point. The Curses.Blinkenlights interface has achieved basic working functionality.
290 lines
9.9 KiB
Python
290 lines
9.9 KiB
Python
# Copyright (C) 2002 John Goerzen
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# Thread support module
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# <jgoerzen@complete.org>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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from threading import *
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from StringIO import StringIO
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import sys, traceback, thread, profile
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from offlineimap.ui import UIBase # for getglobalui()
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profiledir = None
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def setprofiledir(newdir):
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global profiledir
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profiledir = newdir
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######################################################################
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# General utilities
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######################################################################
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def semaphorereset(semaphore, originalstate):
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"""Wait until the semaphore gets back to its original state -- all acquired
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resources released."""
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for i in range(originalstate):
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semaphore.acquire()
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# Now release these.
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for i in range(originalstate):
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semaphore.release()
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def semaphorewait(semaphore):
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semaphore.acquire()
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semaphore.release()
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def threadsreset(threadlist):
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for thr in threadlist:
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thr.join()
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class threadlist:
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def __init__(self):
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self.lock = Lock()
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self.list = []
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def add(self, thread):
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self.lock.acquire()
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try:
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self.list.append(thread)
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finally:
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self.lock.release()
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def remove(self, thread):
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self.lock.acquire()
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try:
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self.list.remove(thread)
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finally:
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self.lock.release()
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def pop(self):
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self.lock.acquire()
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try:
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if not len(self.list):
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return None
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return self.list.pop()
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finally:
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self.lock.release()
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def reset(self):
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while 1:
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thread = self.pop()
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if not thread:
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return
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thread.join()
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######################################################################
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# Exit-notify threads
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######################################################################
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exitcondition = Condition(Lock())
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exitthreads = []
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inited = 0
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def initexitnotify():
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"""Initialize the exit notify system. This MUST be called from the
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SAME THREAD that will call monitorloop BEFORE it calls monitorloop.
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This SHOULD be called before the main thread starts any other
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ExitNotifyThreads, or else it may miss the ability to catch the exit
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status from them!"""
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pass
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def exitnotifymonitorloop(callback):
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"""Enter an infinite "monitoring" loop. The argument, callback,
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defines the function to call when an ExitNotifyThread has terminated.
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That function is called with a single argument -- the ExitNotifyThread
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that has terminated. The monitor will not continue to monitor for
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other threads until the function returns, so if it intends to perform
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long calculations, it should start a new thread itself -- but NOT
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an ExitNotifyThread, or else an infinite loop may result. Furthermore,
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the monitor will hold the lock all the while the other thread is waiting.
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"""
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global exitcondition, exitthreads
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while 1: # Loop forever.
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exitcondition.acquire()
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while not len(exitthreads):
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exitcondition.wait(1)
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while len(exitthreads):
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callback(exitthreads.pop(0)) # Pull off in order added!
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exitcondition.release()
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def threadexited(thread):
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"""Called when a thread exits."""
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ui = UIBase.getglobalui()
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if thread.getExitCause() == 'EXCEPTION':
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if isinstance(thread.getExitException(), SystemExit):
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# Bring a SystemExit into the main thread.
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# Do not send it back to UI layer right now.
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# Maybe later send it to ui.terminate?
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raise SystemExit
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ui.threadException(thread) # Expected to terminate
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sys.exit(100) # Just in case...
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os._exit(100)
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elif thread.getExitMessage() == 'SYNC_WITH_TIMER_TERMINATE':
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ui.terminate()
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# Just in case...
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sys.exit(100)
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os._exit(100)
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else:
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ui.threadExited(thread)
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class ExitNotifyThread(Thread):
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"""This class is designed to alert a "monitor" to the fact that a thread has
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exited and to provide for the ability for it to find out why."""
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def run(self):
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global exitcondition, exitthreads, profiledir
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self.threadid = thread.get_ident()
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try:
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if not profiledir: # normal case
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Thread.run(self)
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else:
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prof = profile.Profile()
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try:
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prof = prof.runctx("Thread.run(self)", globals(), locals())
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except SystemExit:
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pass
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prof.dump_stats( \
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profiledir + "/" + str(self.threadid) + "_" + \
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self.getName() + ".prof")
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except:
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self.setExitCause('EXCEPTION')
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self.setExitException(sys.exc_info()[1])
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sbuf = StringIO()
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traceback.print_exc(file = sbuf)
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self.setExitStackTrace(sbuf.getvalue())
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else:
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self.setExitCause('NORMAL')
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if not hasattr(self, 'exitmessage'):
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self.setExitMessage(None)
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exitcondition.acquire()
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exitthreads.append(self)
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exitcondition.notify()
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exitcondition.release()
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def setExitCause(self, cause):
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self.exitcause = cause
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def getExitCause(self):
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"""Returns the cause of the exit, one of:
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'EXCEPTION' -- the thread aborted because of an exception
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'NORMAL' -- normal termination."""
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return self.exitcause
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def setExitException(self, exc):
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self.exitexception = exc
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def getExitException(self):
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"""If getExitCause() is 'EXCEPTION', holds the value from
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sys.exc_info()[1] for this exception."""
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return self.exitexception
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def setExitStackTrace(self, st):
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self.exitstacktrace = st
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def getExitStackTrace(self):
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"""If getExitCause() is 'EXCEPTION', returns a string representing
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the stack trace for this exception."""
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return self.exitstacktrace
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def setExitMessage(self, msg):
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"""Sets the exit message to be fetched by a subsequent call to
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getExitMessage. This message may be any object or type except
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None."""
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self.exitmessage = msg
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def getExitMessage(self):
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"""For any exit cause, returns the message previously set by
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a call to setExitMessage(), or None if there was no such message
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set."""
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return self.exitmessage
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######################################################################
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# Instance-limited threads
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######################################################################
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instancelimitedsems = {}
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instancelimitedlock = Lock()
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def initInstanceLimit(instancename, instancemax):
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"""Initialize the instance-limited thread implementation to permit
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up to intancemax threads with the given instancename."""
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instancelimitedlock.acquire()
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if not instancelimitedsems.has_key(instancename):
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instancelimitedsems[instancename] = BoundedSemaphore(instancemax)
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instancelimitedlock.release()
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class InstanceLimitedThread(ExitNotifyThread):
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def __init__(self, instancename, *args, **kwargs):
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self.instancename = instancename
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apply(ExitNotifyThread.__init__, (self,) + args, kwargs)
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def start(self):
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instancelimitedsems[self.instancename].acquire()
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ExitNotifyThread.start(self)
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def run(self):
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try:
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ExitNotifyThread.run(self)
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finally:
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instancelimitedsems[self.instancename].release()
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######################################################################
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# Multi-lock -- capable of handling a single thread requesting a lock
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# multiple times
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######################################################################
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class MultiLock:
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def __init__(self):
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self.lock = Lock()
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self.statuslock = Lock()
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self.locksheld = {}
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def acquire(self):
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"""Obtain a lock. Provides nice support for a single
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thread trying to lock it several times -- as may be the case
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if one I/O-using object calls others, while wanting to make it all
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an atomic operation. Keeps a "lock request count" for the current
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thread, and acquires the lock when it goes above zero, releases when
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it goes below one.
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This call is always blocking."""
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# First, check to see if this thread already has a lock.
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# If so, increment the lock count and just return.
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self.statuslock.acquire()
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try:
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threadid = thread.get_ident()
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if threadid in self.locksheld:
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self.locksheld[threadid] += 1
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return
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else:
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# This is safe because it is a per-thread structure
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self.locksheld[threadid] = 1
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finally:
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self.statuslock.release()
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self.lock.acquire()
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def release(self):
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self.statuslock.acquire()
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try:
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threadid = thread.get_ident()
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if self.locksheld[threadid] > 1:
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self.locksheld[threadid] -= 1
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return
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else:
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del self.locksheld[threadid]
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self.lock.release()
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finally:
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self.statuslock.release()
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