"""
This file shows a simple example of a producer-consumer pattern.
The code removes the race condition using a single condition variable.

Because there is only one consumer, only the notify, wait, and condition check
is inside the critical sections, not the actual consumption.
"""


import random
from threading import Thread, Condition

words = ("adieu","audio","bayou","eerie","queue")

wqueue = []
nqueue = []
cv = Condition()

def wordmaker(n):
    """Adds {n} words to a list"""
    for i in range(n):
        word = random.choice(words)
        print(word)
        wqueue.append(word)
        with cv:
            cv.notify()

def nummaker(n):
    """Adds {n} numbers to a list"""
    for i in range(n):
        num = random.randrange(100,1000)
        print(num)
        nqueue.append(num)
        with cv:
            cv.notify()

def packer(n):
    """Pairs up words and numbers from two lists and displays the result"""
    for i in range(n):
        with cv:    
            cnt = 0
            while len(wqueue) == 0 or len(nqueue) == 0:
                cnt += 1
                cv.wait()
            if cnt > 0: print('ran the loop', cnt, 'times')
        pair = wqueue.pop(), nqueue.pop()
        print(pair)

# Make a thread to run each of the above functions
wworker = Thread(target=wordmaker, args=[1000])
nworker = Thread(target=nummaker, args=[1000])
pworker = Thread(target=packer, args=[1000])

# Make the list-filling threads daemons (no need to join them)
wworker.daemon = True
nworker.daemon = True

# Start all three threads
wworker.start()
nworker.start()
pworker.start()

# Wait for the packing thread to finish
pworker.join()