from os.path import basename from Queue import Queue from random import random from sys import argv, exit from threading import Thread from time import sleep # for creating widgets class Widget: pass # for creating stacks class Stack: def __init__(self): self.__stack = list() def __len__(self): return len(self.__stack) def push(self, item): self.__stack.append(item) def pop(self): return self.__stack.pop() # provides an outline for the execution of the program def main(): # check and parse the command line arguments parse_sys_argv() # setup the variables used by the threads run_flag = [True] queue = Queue(argv[1]) send = Stack() recv = Stack() # start the threads producer = Thread(target=produce, args=(run_flag, queue, send)) consumer = Thread(target=consume, args=(run_flag, queue, recv, producer)) producer.start() consumer.start() # let the threads do their work sleep(argv[2]) run_flag[0] = False consumer.join() # verify that the solution was valid calculate_results(send, recv) # parses and checks the command line arguments def parse_sys_argv(): try: # there should be two command line arguments assert len(argv) == 3 # convert and check argv[1] = abs(int(argv[1])) assert argv[1] > 0 # convert and check argv[2] = abs(float(argv[2])) assert argv[2] > 0 except: # print out usage information print basename(argv[0]), print ' ' # exits the program exit(1) # called by the producer thread def produce(run_flag, queue, send): while run_flag[0]: # simulate production sleep(random()) # put widget in buffer item = Widget() queue.put(item) send.push(item) # called by the consumer thread def consume(run_flag, queue, recv, producer): # consume items while running while run_flag[0]: do_consume(queue, recv) # empty the queue to allow maximum room while not queue.empty(): do_consume(queue, recv) # wait for the producer to end producer.join() # consume any other items that might have been produced while not queue.empty(): do_consume(queue, recv) # executes one consumption operation def do_consume(queue, recv): # get a widget from the queue recv.push(queue.get()) # simulate consumption sleep(random()) # verifies that send and recv were equal def calculate_results(send, recv): print 'Solution has', try: # make sure that send and recv have the same length assert len(send) == len(recv) # check all of the contents of send and recv while send: # check the identity of the items in send and recv assert send.pop() is recv.pop() print 'passed.' except: print 'failed.' # starts the program if __name__ == '__main__': main()