Qt 4.3: waitconditions.cpp Example File (threads/waitconditions/waitconditions.cpp)

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

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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()
     {
         qsrand(QTime(0,0,0).secsTo(QTime::currentTime()));

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

             buffer[i % BufferSize] = "ACGT"[(int)qrand() % 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;
     }