blocking_q.py

# coding=utf-8
import threading

class BlockingQ(object):

    def __init__(self, size):
        self.size = size
        self.q = []
        self.lock = threading.Condition()

    def push(self, obj):
        self.lock.acquire()
        while len(self.q) >= self.size:
            print 'wait push %s\n' % obj
            self.lock.wait()
        self.q.insert(0, obj)
        self.lock.notify()
        self.lock.release()

    def pop(self):
        self.lock.acquire()
        while not self.q:
            print 'wait pop\n'
            self.lock.wait()
        r = self.q.pop()
        # '''an awakened thread does not actually return from its wait() call
        #    until it can reacquire the lock.'''
        # 所以这里notify以后push并没有得到锁，而要等到release之后才能得到锁开始运行
        self.lock.notify()
        self.lock.release()
        return r


q = BlockingQ(3)

def do_push():
    for i in range(10):
        q.push(i)

def do_pop():
    while True:
        o = q.pop()
        print '%s\n' % o

push = threading.Thread(target=do_push)
pop = threading.Thread(target=do_pop)
push.start()
pop.start()