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84 lines
2 KiB
Python
84 lines
2 KiB
Python
# Generator implementation using threads
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import thread
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Killed = 'Generator.Killed'
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class Generator:
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# Constructor
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def __init__(self, func, args):
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self.getlock = thread.allocate_lock()
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self.putlock = thread.allocate_lock()
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self.getlock.acquire()
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self.putlock.acquire()
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self.func = func
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self.args = args
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self.done = 0
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self.killed = 0
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thread.start_new_thread(self._start, ())
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# Internal routine
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def _start(self):
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try:
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self.putlock.acquire()
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if not self.killed:
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try:
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apply(self.func, (self,) + self.args)
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except Killed:
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pass
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finally:
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if not self.killed:
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self.done = 1
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self.getlock.release()
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# Called by producer for each value; raise Killed if no more needed
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def put(self, value):
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if self.killed:
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raise TypeError, 'put() called on killed generator'
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self.value = value
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self.getlock.release() # Resume consumer thread
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self.putlock.acquire() # Wait for next get() call
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if self.killed:
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raise Killed
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# Called by producer to get next value; raise EOFError if no more
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def get(self):
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if self.killed:
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raise TypeError, 'get() called on killed generator'
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self.putlock.release() # Resume producer thread
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self.getlock.acquire() # Wait for value to appear
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if self.done:
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raise EOFError # Say there are no more values
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return self.value
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# Called by consumer if no more values wanted
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def kill(self):
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if self.killed:
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raise TypeError, 'kill() called on killed generator'
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self.killed = 1
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self.putlock.release()
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# Clone constructor
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def clone(self):
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return Generator(self.func, self.args)
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def pi(g):
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k, a, b, a1, b1 = 2L, 4L, 1L, 12L, 4L
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while 1:
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# Next approximation
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p, q, k = k*k, 2L*k+1L, k+1L
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a, b, a1, b1 = a1, b1, p*a+q*a1, p*b+q*b1
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# Print common digits
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d, d1 = a/b, a1/b1
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while d == d1:
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g.put(int(d))
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a, a1 = 10L*(a%b), 10L*(a1%b1)
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d, d1 = a/b, a1/b1
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def test():
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g = Generator(pi, ())
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g.kill()
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g = Generator(pi, ())
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for i in range(10): print g.get(),
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print
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h = g.clone()
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g.kill()
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while 1:
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print h.get(),
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test()
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