waitconditions.cpp Example File

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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:
      Producer(QObject *parent = NULL) : QThread(parent)
      {
      }

      void run() Q_DECL_OVERRIDE
      {
          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
  {
      Q_OBJECT
  public:
      Consumer(QObject *parent = NULL) : QThread(parent)
      {
      }

      void run() Q_DECL_OVERRIDE
      {
          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");
      }

  signals:
      void stringConsumed(const QString &text);
  };

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

  #include "waitconditions.moc"