# Copyright (C) 2002-2012 John Goerzen & contributors # Thread support module # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, write to the Free Software # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA from threading import Lock, Thread, BoundedSemaphore, currentThread try: from Queue import Queue, Empty except ImportError: # python3 from queue import Queue, Empty import traceback import os.path from offlineimap.ui import getglobalui STOP_MONITOR = 'STOP_MONITOR' ###################################################################### # General utilities ###################################################################### def semaphorereset(semaphore, originalstate): """Block until `semaphore` gets back to its original state, ie all acquired resources have been released.""" for i in range(originalstate): semaphore.acquire() # Now release these. for i in range(originalstate): semaphore.release() class threadlist: """Store the list of all threads in the software so it can be used to find out what's running and what's not.""" def __init__(self): self.lock = Lock() self.list = [] def add(self, thread): self.lock.acquire() try: self.list.append(thread) finally: self.lock.release() def remove(self, thread): self.lock.acquire() try: self.list.remove(thread) finally: self.lock.release() def pop(self): self.lock.acquire() try: if not len(self.list): return None return self.list.pop() finally: self.lock.release() def wait(self): while 1: thread = self.pop() if not thread: return thread.join() ###################################################################### # Exit-notify threads ###################################################################### exitthreads = Queue() def monitor(): """An infinite "monitoring" loop watching for finished ExitNotifyThread's. This one is supposed to run in the main thread. :param callback: the function to call when a thread terminated. That function is called with a single argument -- the ExitNotifyThread that has terminated. The monitor will not continue to monitor for other threads until 'callback' returns, so if it intends to perform long calculations, it should start a new thread itself -- but NOT an ExitNotifyThread, or else an infinite loop may result. Furthermore, the monitor will hold the lock all the while the other thread is waiting. :type callback: a callable function """ global exitthreads ui = getglobalui() while True: # Loop forever and call 'callback' for each thread that exited try: # We need a timeout in the get() call, so that ctrl-c can throw # a SIGINT (http://bugs.python.org/issue1360). A timeout with empty # Queue will raise `Empty`. thread = exitthreads.get(True, 60) # request to abort when callback returns true if thread.exit_exception is not None: if isinstance(thread.exit_exception, SystemExit): # Bring a SystemExit into the main thread. # Do not send it back to UI layer right now. # Maybe later send it to ui.terminate? raise SystemExit ui.threadException(thread) # Expected to terminate the program. # Should never hit this line. raise AssertionError("thread has 'exit_exception' set to" " '%s' [%s] but this value is unexpected" " and the ui did not stop the program."% (repr(thread.exit_exception), type(thread.exit_exception))) elif thread.exit_message == STOP_MONITOR: break # Exit the loop here. else: ui.threadExited(thread) except Empty: pass class ExitNotifyThread(Thread): """This class is designed to alert a "monitor" to the fact that a thread has exited and to provide for the ability for it to find out why. All instances are made daemon threads (setDaemon(True), so we bail out when the mainloop dies. The thread can set instance variables self.exit_message for a human readable reason of the thread exit. There is one instance of this class at runtime. The main thread waits for the monitor to end.""" profiledir = None """Class variable that is set to the profile directory if required.""" def __init__(self, *args, **kwargs): super(ExitNotifyThread, self).__init__(*args, **kwargs) # These are all child threads that are supposed to go away when # the main thread is killed. self.setDaemon(True) self.exit_message = None self._exit_exc = None self._exit_stacktrace = None def run(self): """Allow profiling of a run.""" global exitthreads try: if not ExitNotifyThread.profiledir: # normal case Thread.run(self) else: try: import cProfile as profile except ImportError: import profile prof = profile.Profile() try: prof = prof.runctx("Thread.run(self)", globals(), locals()) except SystemExit: pass prof.dump_stats(os.path.join(ExitNotifyThread.profiledir, "%s_%s.prof"% (self.ident, self.getName()))) except Exception as e: # Thread exited with Exception, store it tb = traceback.format_exc() self.set_exit_exception(e, tb) if exitthreads: exitthreads.put(self, True) def set_exit_exception(self, exc, st=None): """Sets Exception and stacktrace of a thread, so that other threads can query its exit status""" self._exit_exc = exc self._exit_stacktrace = st @property def exit_exception(self): """Returns the cause of the exit, one of: Exception() -- the thread aborted with this exception None -- normal termination.""" return self._exit_exc @property def exit_stacktrace(self): """Returns a string representing the stack trace if set""" return self._exit_stacktrace @classmethod def set_profiledir(cls, directory): """If set, will output profile information to 'directory'""" cls.profiledir = directory ###################################################################### # Instance-limited threads ###################################################################### instancelimitedsems = {} instancelimitedlock = Lock() def initInstanceLimit(instancename, instancemax): """Initialize the instance-limited thread implementation to permit up to intancemax threads with the given instancename.""" instancelimitedlock.acquire() if not instancename in instancelimitedsems: instancelimitedsems[instancename] = BoundedSemaphore(instancemax) instancelimitedlock.release() class InstanceLimitedThread(ExitNotifyThread): def __init__(self, instancename, *args, **kwargs): self.instancename = instancename super(InstanceLimitedThread, self).__init__(*args, **kwargs) def start(self): instancelimitedsems[self.instancename].acquire() ExitNotifyThread.start(self) def run(self): try: ExitNotifyThread.run(self) finally: if instancelimitedsems and instancelimitedsems[self.instancename]: instancelimitedsems[self.instancename].release()