Producer Consumer using Semaphores

gistfile1.py

"""
Producer produces numbers 1..10
Consumer runs first & then blocks

Solution: uses semaphores
"""

from threading import Thread
from threading import Semaphore

class SharedBuffer(object):
    def __init__(self):
        self.empty = Semaphore(0)
        self.mutex = Semaphore(1)
        self.slot = []

    def put(self, p):
        """ blocking put """
        self.mutex.acquire()
        try:
            print "put " + str(p)
            self.slot.append( p )
        except:
            print "failed to append"
        self.mutex.release()
        self.empty.release()

    def get(self):
        """ blocking get """
        self.empty.acquire()
        self.mutex.acquire()
        v = self.slot.pop()
        self.mutex.release()
        print "get " + str(v)
        return v

class Producer(Thread):
    def __init__(self,buffer):
        Thread.__init__(self)
        self.buffer = buffer

    def run(self):
        print "[Producer] running"
        for i in range(0, 10):
            self.buffer.put( i )
            print "[Producer] sent " + str(i)

        print "[Producer] dead"

class Consumer(Thread):
    def __init__(self,buffer):
        Thread.__init__(self)
        self.buffer = buffer

    def run(self):
        print "[Consumer] running"
        while(True):
            v = self.buffer.get()
            print "[Consumer] received " + str(v)
            if( v == 9 ):
                break
            
        print "[Consumer] dead"
    

if __name__ == "__main__":
    buffer = SharedBuffer()
    p = Producer(buffer)
    c = Consumer(buffer)
    c.start()
    p.start()

    c.join()