|
| 1 | +# Generator implementation using threads |
| 2 | + |
| 3 | +import thread |
| 4 | + |
| 5 | +Killed = 'Generator.Killed' |
| 6 | + |
| 7 | +class Generator: |
| 8 | + # Constructor |
| 9 | + def __init__(self, func, args): |
| 10 | + self.getlock = thread.allocate_lock() |
| 11 | + self.putlock = thread.allocate_lock() |
| 12 | + self.getlock.acquire() |
| 13 | + self.putlock.acquire() |
| 14 | + self.func = func |
| 15 | + self.args = args |
| 16 | + self.done = 0 |
| 17 | + self.killed = 0 |
| 18 | + thread.start_new_thread(self._start, ()) |
| 19 | + # Internal routine |
| 20 | + def _start(self): |
| 21 | + try: |
| 22 | + self.putlock.acquire() |
| 23 | + if not self.killed: |
| 24 | + try: |
| 25 | + apply(self.func, (self,) + self.args) |
| 26 | + except Killed: |
| 27 | + pass |
| 28 | + finally: |
| 29 | + if not self.killed: |
| 30 | + self.done = 1 |
| 31 | + self.getlock.release() |
| 32 | + # Called by producer for each value; raise Killed if no more needed |
| 33 | + def put(self, value): |
| 34 | + if self.killed: |
| 35 | + raise TypeError, 'put() called on killed generator' |
| 36 | + self.value = value |
| 37 | + self.getlock.release() # Resume consumer thread |
| 38 | + self.putlock.acquire() # Wait for next get() call |
| 39 | + if self.killed: |
| 40 | + raise Killed |
| 41 | + # Called by producer to get next value; raise EOFError if no more |
| 42 | + def get(self): |
| 43 | + if self.killed: |
| 44 | + raise TypeError, 'get() called on killed generator' |
| 45 | + self.putlock.release() # Resume producer thread |
| 46 | + self.getlock.acquire() # Wait for value to appear |
| 47 | + if self.done: |
| 48 | + raise EOFError # Say there are no more values |
| 49 | + return self.value |
| 50 | + # Called by consumer if no more values wanted |
| 51 | + def kill(self): |
| 52 | + if self.killed: |
| 53 | + raise TypeError, 'kill() called on killed generator' |
| 54 | + self.killed = 1 |
| 55 | + self.putlock.release() |
| 56 | + # Clone constructor |
| 57 | + def clone(self): |
| 58 | + return Generator(self.func, self.args) |
| 59 | + |
| 60 | +def pi(g): |
| 61 | + k, a, b, a1, b1 = 2L, 4L, 1L, 12L, 4L |
| 62 | + while 1: |
| 63 | + # Next approximation |
| 64 | + p, q, k = k*k, 2L*k+1L, k+1L |
| 65 | + a, b, a1, b1 = a1, b1, p*a+q*a1, p*b+q*b1 |
| 66 | + # Print common digits |
| 67 | + d, d1 = a/b, a1/b1 |
| 68 | + while d == d1: |
| 69 | + g.put(int(d)) |
| 70 | + a, a1 = 10L*(a%b), 10L*(a1%b1) |
| 71 | + d, d1 = a/b, a1/b1 |
| 72 | + |
| 73 | +def test(): |
| 74 | + g = Generator(pi, ()) |
| 75 | + g.kill() |
| 76 | + g = Generator(pi, ()) |
| 77 | + for i in range(10): print g.get(), |
| 78 | + print |
| 79 | + h = g.clone() |
| 80 | + g.kill() |
| 81 | + while 1: |
| 82 | + print h.get(), |
| 83 | + |
| 84 | +test() |
0 commit comments