Qt生产者消费者实验：等待条件QWaitCondition

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/*使用QWaitCondition和QMutex可以实现比信号量更精确的控制*/#include <QtCore>#include <iostream>//const int DataSize = 100000;//const int BufferSize = 4096;const int DataSize = 100;const int BufferSize = 100;char buffer[BufferSize];//与信号量不同的程序QWaitCondition bufferIsNotFull; //QWaitCondition允许在一定条件下触发其它多个线程QWaitCondition bufferIsNotEmpty;QMutex mutex;int usedSpace = 0;//不是信号量，而是用来代表在缓冲器中存在多少个“用过的”字节//生产者class Producer : public QThread{public:    void run();};void Producer::run(){    for (int i = 0; i < DataSize; ++i) {        mutex.lock();//锁定：保护对usedSpace变量的访问        //如果缓冲区都是用过的字节，那么就等待        while (usedSpace == BufferSize)            bufferIsNotFull.wait(&mutex);//wait的过程：解锁－>阻塞当前线程－>满足条件－>锁定－>返回        buffer[i % BufferSize] = "ACGT"[uint(rand()) % 4];        std::cerr<<"P";//代表一次生产者线程的运行        ++usedSpace;        bufferIsNotEmpty.wakeAll();//Wakes all threads waiting on the wait condition.        mutex.unlock();//解锁    }}//消费者class Consumer : public QThread{public:    void run();};void Consumer::run(){    for (int i = 0; i < DataSize; ++i) {        mutex.lock();//        //如果缓冲区里“用过的”字节数目为0，则等待        while (usedSpace == 0)            bufferIsNotEmpty.wait(&mutex);        //std::cerr << buffer[i % BufferSize];        char Cons = buffer[i % BufferSize];        std::cerr<<"c";        --usedSpace;        bufferIsNotFull.wakeAll();        mutex.unlock();    }    std::cerr << std::endl;}int main(){    Producer producer;    Consumer consumer;    producer.start();    consumer.start();    producer.wait();    consumer.wait();    return 0;}

执行结果：

(1)

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

PcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPc

(2)

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

结果1

PPPPPPPPPPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcccccccccc

结果2

PPPPPPPPPPcPcPcPcPcPcPcPcPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPcc

结果3

PPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPcccccccccc

(3)

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

PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP

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