"""
Copyright 2010 Shao-Chuan Wang <shaochuan.wang AT gmail DOT com>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""
import time
from threading import Thread, Condition, Lock
from Queue import Queue, Empty
from functools import partial
class CmdThread(Thread):
def __init__(self):
Thread.__init__(self)
self._queue = Queue()
self._status = 'NORMAL'
self._statusLock = Lock()
self._possibleStatus = ('NORMAL', 'SLEEPING', 'DONE')
self._condition = Condition(self._statusLock)
self.daemon = True
self.start()
def run(self):
while True:
self._condition.acquire()
if self._status == 'DONE':
self._condition.release()
break
if self._status == 'SLEEPING':
self._condition.wait() # this function will release the lock when going to sleep
self._condition.release()
try:
task = self._queue.get_nowait()
except Empty:
self._condition.acquire()
self._status = 'SLEEPING'
self._condition.wait()
# Here, we don't change the status to 'NORMAL' here
# The status is supposed to be changed by the waker
# Before this command thread wakes up.
self._condition.release()
continue
if callable(task):
try:
task()
except Exception:
self._statusLock.acquire()
self._status = 'DONE'
self._statusLock.release()
raise
else:
# you can define the task interface here.
pass
def addCmd(self, callableObj, *args, **argd):
""" non-blocking call.
"""
assert(callable(callableObj))
self._condition.acquire()
if self._status == 'DONE':
self._condition.release()
return
self._queue.put(partial(callableObj, *args, **argd))
self._status = 'NORMAL'
self._condition.notifyAll()
self._condition.release()
def close(self, timeout=None):
""" blocking call, return after close/cancel is done.
"""
undoneJobs = []
self._condition.acquire()
if self._status == 'DONE':
self._condition.release()
return
self._status = 'DONE'
self._condition.notifyAll()
while not self._queue.empty():
undoneJobs.append(self._queue.get())
self._condition.release()
self.join(timeout)
return undoneJobs
def pause(self, timeout=None):
""" non-blocking call, return after pause is done.
"""
self._condition.acquire()
if self._status == 'DONE':
self._condition.release()
return
self._status = 'SLEEPING'
self._condition.notifyAll()
self._condition.release()
def resume(self):
""" non-blocking call.
"""
self._condition.acquire()
if self._status == 'DONE':
self._condition.release()
return
self._status = 'NORMAL'
self._condition.notifyAll()
self._condition.release()
def hasCmd(self):
""" non-blocking call.
"""
return not self._queue.empty()
def demo():
def exampleTask():
print 'job beginning...'
time.sleep(2)
print 'job finishing...'
cmdObj = CmdThread()
for i in xrange(5):
cmdObj.addCmd(exampleTask)
return cmdObj
if __name__=='__main__':
cmd = demo()
print 'main thread is going to sleep.'
time.sleep(3)
print 'main threading is going to close the cmd thread.'
print cmd.close()
Diff to Previous Revision
--- revision 2 2010-12-20 00:28:52
+++ revision 3 2010-12-20 00:35:28
@@ -54,7 +54,9 @@
self._condition.acquire()
self._status = 'SLEEPING'
self._condition.wait()
- self._status = 'NORMAL'
+ # Here, we don't change the status to 'NORMAL' here
+ # The status is supposed to be changed by the waker
+ # Before this command thread wakes up.
self._condition.release()
continue
