QT之使用QMutex/ QMutexLocker互斥量同步线程小例子

    接上一篇，在多线程中基本上都需要解决线程同步问题，本篇文章主要将介绍如何使用QMutex/ QMutexLocker互斥量来同步线程。

    首先，先回顾下Qt官网QThreads general usage介绍，其中有一段基本上介绍了其使用方法，如下：

    The main thing in this example to keep in mind when using a QThread is that it's not a thread. It's a wrapper around a thread object. This wrapper provides the signals, slots and methods to easily use the thread object within a Qt project. To use it, prepare a QObject subclass with all your desired functionality in it. Then create a new QThread instance, push the QObject onto it using moveToThread(QThread*) of the QObject instance and call start() on the QThread instance. That's all. You set up the proper signal/slot connections to make it quit properly and such, and that's all.

    现在，直接上售票的小例子：

    Step1. 按Qt介绍的用法：先创建一个继承QObject的类，把要执行的函数包装进里面：

.h 文件代码如下：

#ifndef TICKETSELLER_H#define TICKETSELLER_H#include <QObject>#include <QThread>#include <QMutex>#include <string>class TicketSeller : public QObject{public:    TicketSeller();    ~TicketSeller();public slots:    void sale();public:    int* tickets;    QMutex* mutex;    std::string name;};#endif // TICKETSELLER_H

.cpp 文件代码如下：

#include "ticketseller.h"#include <iostream>TicketSeller::TicketSeller(){    tickets = 0;    mutex = NULL;}TicketSeller::~TicketSeller(){}void TicketSeller::sale(){    while((*tickets) > 0)    {        mutex->lock();        std::cout << name << " : " << (*tickets)-- << std::endl;        mutex->unlock();    }    /*while((*tickets) > 0)    {        QMutexLocker locker(mutex);        std::cout << name << " : " << (*tickets)-- << std::endl;        locker.unlock();    }*/}

    Step2. 按Qt介绍的用法：创建一个实例，使用moveToThread将对象移至QThread内，并连接信号槽，最后调用start()方法：

main.cpp 文件代码如下：

#include <QCoreApplication>#include <QMutex>#include <QThread>#include <string>#include "ticketseller.h"int main(int argc, char *argv[]){    QCoreApplication a(argc, argv);       int ticket = 100;    QMutex mutex;    /*创建设置线程1*/    //创建线程1    QThread t1;    TicketSeller seller1;    //设置线程1    seller1.tickets = &ticket;    seller1.mutex = &mutex;    seller1.name = "seller1";    //将对象移动到线程    seller1.moveToThread(&t1);    /*创建设置线程2*/    //创建线程2    QThread t2;    TicketSeller seller2;    seller2.tickets = &ticket;    seller2.mutex = &mutex;    seller2.name = "seller2";    //将对象移动到线程    seller2.moveToThread(&t2);    QObject::connect(&t1, &QThread::started, &seller1, &TicketSeller::sale);    QObject::connect(&t2, &QThread::started, &seller2, &TicketSeller::sale);    t1.start();    t2.start();    return a.exec();}

    QT 中使用 QMutex/ QMutexLocker 比Window API CreateMutex 配合 WaitForSingleObject 同步线程要简单得多。