Qt生产者消费者实验(1)：信号量

/*生产者和消费者实验使用信号量实现线程的同步*/#include <QtCore>#include <iostream>const int DataSize = 100;const int BufferSize = 10;char buffer[BufferSize];//定义两个信号量QSemaphore freeSpace(BufferSize);QSemaphore usedSpace(0);//刚开始没有生产者写好的数据，所以初始化为0//生产者class Producer : public QThread{public:    void run();};//start()调用的就是run()函数。他是一个虚函数，默认情况下调用exec()//从该函数返回表示线程已经结束//生产者随机生成一个字母填充进缓冲区buffervoid Producer::run(){    for (int i = 0; i < DataSize; ++i) {        freeSpace.acquire();//获取“自由的”字节        buffer[i % BufferSize] = "ACGT"[uint(rand()) % 4];        std::cerr << "P";        usedSpace.release();//转换为“用过的”(填充过的)字节    }}//消费者class Consumer : public QThread{public:    void run();};//将生产者填充进“用过的”字节的字幕读取并输出到控制台void Consumer::run(){    for (int i = 0; i < DataSize; ++i) {        usedSpace.acquire();//获取“用过的”资源，如果没有则一直阻塞，直到有资源为止        //std::cerr << buffer[i % BufferSize];        char Cons = buffer[i % BufferSize];        std::cerr <<"c";        freeSpace.release();    }    std::cerr << std::endl;}//主程序int main(){    Producer producer;    Consumer consumer;    producer.start();//通过调用run来执行线程    consumer.start();    producer.wait();//wait()和pthread_join()功能类似    consumer.wait();    return 0;}

执行结果：

BufferSize 不同对应的结果也稍有不同

(1)

const int DataSize = 100;
const int BufferSize = 1;

PcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPc

(2)

const int DataSize = 100;
const int BufferSize = 10;

PPPPPPPPPPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcccccccccc

(3)

const int DataSize = 100;
const int BufferSize = 100;

PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc