线程使用之条件等待模拟生产者消费者

producer_customer.h

#include <QThread>class Producer : public QThread{public:    Producer();protected:    void run();};class Customer : public QThread{public:    Customer();protected:    void run();};

producer_customer.h

#include "producer_customer.h"#include <QWaitCondition>//等待条件#include <QMutex>#include <QDebug>QWaitCondition cond;QMutex mutex;int global = 0;int flag = 0;Producer::Producer(){}void Producer::run(){    while(1)    {        mutex.lock();        int tmp = global;        global += 2;        qDebug()<< currentThreadId()                << ", Producer: "                << tmp                << "-->"                << global;        //判定标志，是否有人在等待        while(!flag)        {            mutex.unlock();            usleep(200);            mutex.lock();        }        cond.wakeAll();//唤醒所有消费者        //cond.wakeOne();        qDebug() << "producer finished! ----------------------";        //只唤醒一个处于等待的消费者        mutex.unlock();        sleep(2);    }}Customer::Customer(){}void Customer::run(){    while(1)    {        mutex.lock();        //++        flag ++;        cond.wait(&mutex);//等待生产者唤醒消费        //--        flag --;        int tmp = global;        global--;        qDebug()<< currentThreadId()                << ", Customer: "                << tmp                << "-->"                << global;        qDebug() << "customer finished!================";        mutex.unlock();        sleep(1);    }}

main.cpp

#include <QApplication>#include <QDebug>#include "producer_customer.h"int main(int argc, char *argv[]){    QApplication a(argc, argv);    Producer *p = new Producer;    Customer *c1 = new Customer;    Customer *c2 = new Customer;    p->start();    c1->start();    c2->start();    return a.exec();}