/Demo/threads/Generator.py
http://unladen-swallow.googlecode.com/ · Python · 92 lines · 72 code · 11 blank · 9 comment · 15 complexity · f642da2de5b06429fd0cefc9be12a5ee MD5 · raw file
- # Generator implementation using threads
- import sys
- import thread
- class Killed(Exception):
- pass
- class Generator:
- # Constructor
- def __init__(self, func, args):
- self.getlock = thread.allocate_lock()
- self.putlock = thread.allocate_lock()
- self.getlock.acquire()
- self.putlock.acquire()
- self.func = func
- self.args = args
- self.done = 0
- self.killed = 0
- thread.start_new_thread(self._start, ())
- # Internal routine
- def _start(self):
- try:
- self.putlock.acquire()
- if not self.killed:
- try:
- apply(self.func, (self,) + self.args)
- except Killed:
- pass
- finally:
- if not self.killed:
- self.done = 1
- self.getlock.release()
- # Called by producer for each value; raise Killed if no more needed
- def put(self, value):
- if self.killed:
- raise TypeError, 'put() called on killed generator'
- self.value = value
- self.getlock.release() # Resume consumer thread
- self.putlock.acquire() # Wait for next get() call
- if self.killed:
- raise Killed
- # Called by producer to get next value; raise EOFError if no more
- def get(self):
- if self.killed:
- raise TypeError, 'get() called on killed generator'
- self.putlock.release() # Resume producer thread
- self.getlock.acquire() # Wait for value to appear
- if self.done:
- raise EOFError # Say there are no more values
- return self.value
- # Called by consumer if no more values wanted
- def kill(self):
- if self.killed:
- raise TypeError, 'kill() called on killed generator'
- self.killed = 1
- self.putlock.release()
- # Clone constructor
- def clone(self):
- return Generator(self.func, self.args)
- def pi(g):
- k, a, b, a1, b1 = 2L, 4L, 1L, 12L, 4L
- while 1:
- # Next approximation
- p, q, k = k*k, 2L*k+1L, k+1L
- a, b, a1, b1 = a1, b1, p*a+q*a1, p*b+q*b1
- # Print common digits
- d, d1 = a//b, a1//b1
- while d == d1:
- g.put(int(d))
- a, a1 = 10L*(a%b), 10L*(a1%b1)
- d, d1 = a//b, a1//b1
- def test():
- g = Generator(pi, ())
- g.kill()
- g = Generator(pi, ())
- for i in range(10): print g.get(),
- print
- h = g.clone()
- g.kill()
- while 1:
- print h.get(),
- sys.stdout.flush()
- test()