waitconditions.py

#!/usr/bin/env python


#############################################################################
##
## Copyright (C) 2013 Riverbank Computing Limited.
## Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
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## This file is part of the examples of PyQt.
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#############################################################################


import sys
import random

from PyQt5.QtCore import QCoreApplication, QMutex, QThread, QWaitCondition


DataSize = 100000
BufferSize = 8192
buffer = list(range(BufferSize))

bufferNotEmpty = QWaitCondition()
bufferNotFull = QWaitCondition()
mutex = QMutex()
numUsedBytes = 0


class Producer(QThread):
    def run(self):
        global numUsedBytes

        for i in range(DataSize):
            mutex.lock()
            if numUsedBytes == BufferSize:
                bufferNotFull.wait(mutex)
            mutex.unlock()
            
            buffer[i % BufferSize] = "ACGT"[random.randint(0, 3)]

            mutex.lock()
            numUsedBytes += 1
            bufferNotEmpty.wakeAll()
            mutex.unlock()


class Consumer(QThread):
    def run(self):
        global numUsedBytes

        for i in range(DataSize):
            mutex.lock()
            if numUsedBytes == 0:
                bufferNotEmpty.wait(mutex)
            mutex.unlock()
            
            sys.stderr.write(buffer[i % BufferSize])

            mutex.lock()
            numUsedBytes -= 1
            bufferNotFull.wakeAll()
            mutex.unlock()
            
        sys.stderr.write("\n")


if __name__ == '__main__':
    app = QCoreApplication(sys.argv)
    producer = Producer()
    consumer = Consumer()
    producer.start()
    consumer.start()
    producer.wait()
    consumer.wait()