Source code for eg.Classes.ThreadWorker

# -*- coding: utf-8 -*-
# This file is part of EventGhost.
# Copyright © 2005-2016 EventGhost Project <>
# EventGhost 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
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# any later version.
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from collections import deque
from functools import partial
from sys import exc_info, _getframe
from threading import currentThread, Event, Thread
from time import clock
from traceback import extract_stack, format_list

# Local imports
import eg
from eg.WinApi.Dynamic import (
    byref, COINIT_APARTMENTTHREADED, CoInitializeEx, CoUninitialize,
    CreateEvent, DispatchMessage, HANDLE, MSG, MsgWaitForMultipleObjects,

[docs]class ThreadWorker(object): """ General purpose message pumping thread, that is used in many places. """ # used for automatic documentation creation __docsort__ = ( "Start, Stop, Setup, Finish, Call, Func, CallWait" ) def __init__(self, *args, **kwargs): self.__alive = True self.__queue = deque() self.__setupFunc = partial(self.Setup, *args, **kwargs) self.__wakeEvent = CreateEvent(None, 0, 0, None) self.__dummyEvent = CreateEvent(None, 0, 0, None) self.__events = (HANDLE * 1)(self.__wakeEvent) self.__thread = Thread( group=None, target=self.__MainLoop, name=self.__class__.__name__, ) def AppendAction(self, action): self.__queue.append(action) SetEvent(self.__wakeEvent)
[docs] def Call(self, func, *args, **kwargs): """ Queue a function and its arguments for execution in the :class:`eg.ThreadWorker` thread. Doesn't wait for the completion of the function. """ action = ThreadWorkerAction(func, args, kwargs, True) self.__queue.append(action) SetEvent(self.__wakeEvent) return action
[docs] def CallWait(self, func, timeout=10.0): """ Queue a function for execution in the :class:`eg.ThreadWorker` thread. Waits for completion of the function and returns its result. The function must have no arguments, so if some are needed one should create a argumentless function with functools.partial. .. note:: This function is deprecated. Use the :meth:`Func` wrapper instead. """ return self.Func(func, timeout)()
def ClearPendingEvents(self): self.__queue.clear()
[docs] def Finish(self): """ This will be called inside the thread when it finishes. It will even be called if the thread exits through an exception. """ pass
[docs] def Func(self, func, timeout=None): """ Wraps a function for synchronized execution in the :class:`eg.ThreadWorker` thread. The returned object can be called like the unwrapped function but will execute in the :class:`eg.ThreadWorker` thread regardless were it is called from. The call will deliver the return value of the function. If the function raises an exception, it will be propagated to the calling thread. The optional *timeout* value specifies the maximal time to wait for the completion of the function in floating point seconds. If the timeout expires, the call will raise an exception. If timeout is not specified or None (the default), it will wait forever. Example usage:: threadWorker = eg.ThreadWorker() threadWorker.Start() def MyFunction(param): print param return "Hello Caller!" wrappedFunc = threadWorker.Func(MyFunction, 5.0) result = wrappedFunc("Hello World!") print result """ def Wrapper(*args, **kwargs): action = ThreadWorkerAction(func, args, kwargs, False) self.__queue.append(action) SetEvent(self.__wakeEvent) action.processed.wait(timeout) if timeout is not None and not action.processed.isSet(): eg.PrintStack() raise Exception("Timeout while calling %s" % func.__name__) if action.exceptionInfo is not None: excType, excValue, excTraceback = action.exceptionInfo raise excType, excValue, excTraceback return action.returnValue return Wrapper
def HandleAction(self, action): action() def Poll(self): pass
[docs] def Setup(self, *args, **kwargs): """ This will be called inside the thread at the beginning. Any exception raised in this method will be propagated to the :meth:`Start` method and re-raised there. """ pass
[docs] def Start(self, timeout=None): """ Start the thread execution. The thread will first call the self.Setup method with the parameters assigned by the :class:`eg.ThreadWorker` constructor and waits till :meth:`Setup` has finished its execution. If an exception is raised in self.Setup, this exception will be propagated to the self.Start method, so it will look like self.Start has directly called :meth:`Setup`. But :meth:`Setup` is actually executed in the new thread. """ if timeout is None: timeout = eg.config.defaultThreadStartTimeout if timeout > 0.0: self.__thread.start() try: self.Func(self.__setupFunc, timeout)() except: self.Stop() raise else: self.__thread.start() self.Call(self.__setupFunc) return True
[docs] def Stop(self, timeout=0.0): """ Call this if the thread should stop. """ def StopCall(): self.__alive = False self.Call(StopCall) if timeout > 0.0: self.__thread.join(timeout) return self.__thread.isAlive()
def Wait(self, timeout): endTime = clock() + timeout events = (HANDLE * 1)(self.__dummyEvent) while True: resultCode = MsgWaitForMultipleObjects( 1, events, 0, int(timeout * 1000), QS_ALLINPUT ) if resultCode == WAIT_OBJECT_0: # event signaled - should never happen! raise Exception("Got unknown event in ThreadWorker.Wait()") elif resultCode == WAIT_TIMEOUT: # Timeout expired. return # must be a message. self.__PumpWaitingMessages() timeout = endTime - clock() if timeout < 0: return def WaitOnEvent(self, event, timeout=10): endTime = clock() + timeout events = (HANDLE * 1)(event) while self.__alive: resultCode = MsgWaitForMultipleObjects( 1, events, 0, int(timeout * 1000), QS_ALLINPUT ) if resultCode == WAIT_OBJECT_0: return True elif resultCode == WAIT_TIMEOUT: # Timeout expired. return # must be a message. self.__PumpWaitingMessages() timeout = endTime - clock() if timeout < 0: return True def __DoOneEvent(self): try: resultCode = MsgWaitForMultipleObjects( 1, self.__events, 0, 10000, QS_ALLINPUT ) if resultCode == WAIT_OBJECT_0: while 1: try: action = self.__queue.popleft() except IndexError: break try: self.HandleAction(action) except: action.PrintUnhandledException() finally: # if the frame reference would not be removed, the # action would never be garbage collected. action.callersFrame = None elif resultCode == WAIT_OBJECT_0 + 1: self.__PumpWaitingMessages() elif resultCode == WAIT_TIMEOUT: # Our timeout has elapsed. self.Poll() else: raise RuntimeError("unexpected win32wait return value") except: eg.PrintDebugNotice("Exception in __DoOneEvent") eg.PrintTraceback() @eg.LogItWithReturn def __MainLoop(self): """ Mainloop of the new thread. """ CoInitializeEx(None, COINIT_APARTMENTTHREADED) self.__PumpWaitingMessages() try: while self.__alive: self.__DoOneEvent() finally: self.Finish() CoUninitialize() def __PumpWaitingMessages(self): msg = MSG() while PeekMessage(byref(msg), 0, 0, 0, PM_REMOVE): if msg.message == WM_QUIT: self.__alive = False return DispatchMessage(byref(msg))
class ThreadWorkerAction(object): """ Represents an item that will be put on the ThreadWorker queue to be executed there. """ __slots__ = [ "time", "func", "args", "kwargs", "returnValue", "processed", "exceptionInfo", "raiseException", "callersFrame", ] def __init__(self, func, args, kwargs, raiseException=True): self.time = clock() self.func = func self.args = args self.kwargs = kwargs self.returnValue = None self.processed = Event() self.raiseException = raiseException self.exceptionInfo = None self.callersFrame = _getframe().f_back.f_back def __call__(self): try: self.returnValue = self.func(*self.args, **self.kwargs) except Exception: if self.raiseException: raise else: self.exceptionInfo = exc_info() finally: self.processed.set() def PrintUnhandledException(self): name = currentThread().name lines = [ "Unhandled exception in WorkerThread <%s>:\n" % name, "Callers stack:\n" ] lines += format_list(extract_stack(self.callersFrame)) eg.PrintError("".join(lines).rstrip()) eg.PrintTraceback()