Qt 4.0: waitconditions.cpp Example File (threads/waitconditions/waitconditions.cpp)

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# waitconditions.cpp Example File
threads/waitconditions/waitconditions.cpp

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        **
        ** 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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        ** 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;
        }