jens
7412e813bc
git-svn-id: http://moon:8086/svn/software/trunk/projects/opencv@329 b431acfa-c32f-4a4a-93f1-934dc6c82436
92 lines
2.0 KiB
Python
Executable File
92 lines
2.0 KiB
Python
Executable File
"""A simple thread subclass for making ev3 function calls asynchronous.
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EXAMPLE USAGE:
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import time
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from ev3 import *
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finished = False
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def keep_alive_finished(result):
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global finished
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print 'The keep_alive() function returned: ', result
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finished = True
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if ("__main__" == __name__):
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try:
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async_thread = async.AsyncThread()
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with ev3.EV3() as brick:
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async_thread.put(brick.keep_alive, keep_alive_finished)
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while (not finished):
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print 'Waiting...'
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time.sleep(0.1)
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except ev3.EV3Error as ex:
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print 'An error occurred: ', ex
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async_thread.stop()
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"""
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import threading
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import queue
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class AsyncThread(threading.Thread):
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"""A simple thread subclass maintains a queue of functions to call."""
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_STOP_QUEUE_ITEM = 'STOP'
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def __init__(self):
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"""Creates and starts a new thread."""
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super(AsyncThread, self).__init__()
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self._daemon = True
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self._queue = Queue.Queue()
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self.start()
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def run(self):
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"""This function is called automatically by the Thread class."""
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try:
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while(True):
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item = self._queue.get(block=True)
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if (self._STOP_QUEUE_ITEM == item):
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break
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ev3_func, cb, args, kwargs = item
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cb(ev3_func(*args, **kwargs))
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except KeyboardInterrupt:
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pass
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def stop(self):
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"""Instructs the thread to exit after the current function is
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finished.
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"""
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with self._queue.mutex:
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self._queue.queue.clear()
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self._queue.put(self._STOP_QUEUE_ITEM)
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def put(self, ev3_func, cb, *args, **kwargs):
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"""Adds a new function to the queue. The cb (callback) parameter should
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be a function that accepts the result as its only parameter.
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"""
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self._queue.put((ev3_func, cb, args, kwargs))
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