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# semaphores.cpp Example File
threads/semaphores/semaphores.cpp

        /****************************************************************************
        **
        ** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
        **
        ** This file is part of the example classes of the Qt Toolkit.
        **
        ** Licensees holding valid Qt Preview licenses may use this file in
        ** accordance with the Qt Preview License Agreement provided with the
        ** Software.
        **
        ** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
        ** information about Qt Commercial License Agreements.
        **
        ** Contact info@trolltech.com if any conditions of this licensing are
        ** not clear to you.
        **
        ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
        ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        **
        ****************************************************************************/

        #include <QtCore>

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

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

        QSemaphore freeBytes(BufferSize);
        QSemaphore usedBytes;

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

        void Producer::run()
        {
            for (int i = 0; i < DataSize; ++i) {
                freeBytes.acquire();
                buffer[i % BufferSize] = "ACGT"[(int)rand() % 4];
                usedBytes.release();
            }
        }

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

        void Consumer::run()
        {
            for (int i = 0; i < DataSize; ++i) {
                usedBytes.acquire();
                fprintf(stderr, "%c", buffer[i % BufferSize]);
                freeBytes.release();
            }
            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;
        }