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#------------------------------------------------------------------------------
# Copyright (c) 2005, Enthought, Inc.
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in enthought/LICENSE.txt and may be redistributed only
# under the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
# Thanks for using Enthought open source!
#
# Author: Enthought, Inc.
# Description: <Enthought util package component>
#------------------------------------------------------------------------------
import threading
class Worker(threading.Thread):
""" Performs numerically intensive computations on a separate thread.
Computations that take more than ~0.1 second should not be run in the
same thread as the user interface.
Typical usage:
>>> worker = Worker(name = "my worker thread")
>>> worker.perform_work(my_function_name, args)
>>> worker.start()
>>> worker.cancel()
"""
def __init__(self, **kwds):
""" Passes the thread constructor a name for the thread.
Naming threads makes debugging less impossible. The thread is set to be
a daemon thread, which means that if is the only remaining executing
thread the program will terminate.
"""
self._stopevent = threading.Event()
threading.Thread.__init__(self, **kwds)
self.setDaemon(True)
def perform_work(self, callable, *args, **kwds):
""" Indicates to the thread the method or function and it's arguments.
When the thread begins to run it will execute 'callable' and pass it
'args' and 'kwds'
"""
self.callable = callable
self.args = args
self.kwds = kwds
def run(self):
""" Private method - used only by the threading.Thread module.
Users signal a thread should start to run by calling start().
"""
self.callable(self, *self.args, **self.kwds)
def cancel(self, timeout = None):
""" Signals to the worker thread that it should stop computing.
Calling this method before the thread is started generates an
exception.
"""
self._stopevent.set()
threading.Thread.join(self, timeout)
def abort(self):
""" should the algorithm stop computing?
"""
return self._stopevent.isSet()
if __name__ == "__main__":
import time
def slow_eval(worker, sleep_time):
for i in range(10):
if worker.abort():
return
else:
# pretend to do some intensive computation
time.sleep(sleep_time)
print worker.getName(),' sleeping for: ', sleep_time
return sleep_time
print 'the standard thread is: ', threading.currentThread
worker = Worker(name = "First EnVisage worker thread")
worker.perform_work(slow_eval, 1)
worker.start()
time.sleep(3)
worker.cancel()
worker = Worker(name = "Second EnVisage worker thread")
worker.perform_work(slow_eval, 1)
worker.start()
time.sleep(2)
worker.cancel()
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