import sys
from threading import *
from time import sleep
from random import random
from math import log

running = True
mutex = Semaphore(1)
num_cokes = 5

def consume():
    global num_cokes
    
    mutex.acquire()
    num_cokes -= 1
    print num_cokes
    mutex.release()

def produce():
    global num_cokes

    mutex.acquire()
    num_cokes += 1
    print num_cokes
    mutex.release()

def rand_exponential():
    while 1:
        x = random()
        if x > 0: break
    return -log(x)

def loop(f):
    global running

    while running:
        f()
        t = rand_exponential()
        sleep(t)

def entry(f):
    global running
    
    try:
        loop(f)
    except KeyboardInterrupt:
        running = False

def run_in_thread(function, *args):
    thread = Thread(target=function, args=args)
    thread.start()
    return thread

def main(script, *args):
    global running
    
    t1 = run_in_thread(entry, consume)
    t2 = run_in_thread(entry, produce)

    try:
        while running:
            sleep(1)
    except KeyboardInterrupt:
        running = False

    t1.join()
    t2.join()

if __name__ == '__main__':
    main(*sys.argv)