#!/usr/bin/python

# -*- coding: utf-8 -*-

# 了解多线程的锁，信号量

from atexit import register

from random import randrange

import threading

import time

lock = threading.Lock()

MAX = 5

candytray = threading.BoundedSemaphore(MAX)

def refill():

with lock:

print 'Refilling candy...'

try:

candytray.release()

except ValueError:

print 'full,skipping'

else:

print 'ok'

def buy():

with lock:

print 'buying candy...'

if candytray.acquire(False):

print 'ok'

else:

print 'empty,skipping'

def producer(loops):

for i in xrange(loops):

refill()

time.sleep(randrange(3))

def consumer(loops):

for i in xrange(loops):

buy()

time.sleep(randrange(3))

def _main():

print 'starting at:',time.ctime()

nloops = randrange(2,6)

print 'THE CANDY MATCH (full with %d bars)!' % MAX

threading.Thread(target=consumer,args=(randrange(nloops,nloops+MAX+2),)).start()

# threading.Thread(target=producer,args=(nloops,)).start()

@register

def _atexit():

print 'all DOne at:',time.ctime()

if __name__ == '__main__':

_main()