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# Generator implementation using threads
import thread
Killed = 'Generator.Killed'
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:
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 = 2, 4, 1, 12, 4
while 1:
# Next approximation
p, q, k = k*k, 2*k+1, k+1
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 = 10*(a%b), 10*(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(), end=' ')
print()
h = g.clone()
g.kill()
while 1:
print(h.get(), end=' ')
test()
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