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waitconditions.cpp Example File
^{threads/waitconditions/waitconditions.cpp}

    /****************************************************************************
    **
    ** Copyright (C) 2005-2005 Trolltech AS. All rights reserved.
    **
    ** This file is part of the documentation of the Qt Toolkit.
    **
    ** This file may be used under the terms of the GNU General Public
    ** License version 2.0 as published by the Free Software Foundation
    ** and appearing in the file LICENSE.GPL included in the packaging of
    ** this file.  Please review the following information to ensure GNU
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    ** review the following information:
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    ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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    #include <QtCore>

    #include <stdio.h>
    #include <stdlib.h>

    const int DataSize = 100000;
    const int BufferSize = 8192;
    char buffer[BufferSize];

    QWaitCondition bufferNotEmpty;
    QWaitCondition bufferNotFull;
    QMutex mutex;
    int numUsedBytes = 0;

    class Producer : public QThread
    {
    public:
        void run();
    };

    void Producer::run()
    {
        for (int i = 0; i < DataSize; ++i) {
            mutex.lock();
            if (numUsedBytes == BufferSize)
                bufferNotFull.wait(&mutex);
            mutex.unlock();

            buffer[i % BufferSize] = "ACGT"[(int)rand() % 4];

            mutex.lock();
            ++numUsedBytes;
            bufferNotEmpty.wakeAll();
            mutex.unlock();
        }
    }

    class Consumer : public QThread
    {
    public:
        void run();
    };

    void Consumer::run()
    {
        for (int i = 0; i < DataSize; ++i) {
            mutex.lock();
            if (numUsedBytes == 0)
                bufferNotEmpty.wait(&mutex);
            mutex.unlock();

            fprintf(stderr, "%c", buffer[i % BufferSize]);

            mutex.lock();
            --numUsedBytes;
            bufferNotFull.wakeAll();
            mutex.unlock();
        }
        fprintf(stderr, "\n");
    }

    int main(int argc, char *argv[])
    {
        QCoreApplication app(argc, argv);
        Producer producer;
        Consumer consumer;
        producer.start();
        consumer.start();
        producer.wait();
        consumer.wait();
        return 0;
    }