QT信号量QSemaphore基础学习

QT信号量QSemaphore基础学习

QSemaphore作为QT中的信号量，相当于多把互斥锁，QMutex只锁一次，而QSemaphore能锁多次，且控制多个条件。
如下：先创建一个客户类和一个线程类来使用信号量，
QSemaphore中主要函数为：
acquire(int n = 1)获取资源，默认获取第一个资源，相当于获取资源后加锁，如果没有资源会阻塞到当前位置；
available()获取当前可用资源数量；
release(int n = 1)释放n个资源，相当于开锁；
tryAcquire(int n = 1)尝试获取第n个资源，相当于开启n把锁，开锁成功后返回true，失败返回false，不阻塞。
头文件：

#include 
#include 
#include 
class mythread;

namespace Ui {
class mysemaphore;
}

class mysemaphore : public QMainWindow
{
    Q_OBJECT

public:
    explicit mysemaphore(QWidget *parent = 0);
    ~mysemaphore();

public slots:
    void deleteSlot();
private slots:
    void on_pushButton_clicked();

private:
    Ui::mysemaphore *ui;
    mythread* m_thread;
};


class mythread : public QThread
{
    Q_OBJECT

public:
    mythread();

    virtual void run();
public slots:
    void useSlot();

public:
    QSemaphore m_semaphore;
    int index;
};

cpp文件：

#include "mysemaphore.h"
#include "ui_mysemaphore.h"
#include 
mysemaphore::mysemaphore(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::mysemaphore)
{
    ui->setupUi(this);
    m_thread = new mythread();
    connect(ui->threadbtn,SIGNAL(clicked()),m_thread,SLOT(useSlot()));
    connect(m_thread,SIGNAL(finished()),this,SLOT(deleteSlot()));
}

mysemaphore::~mysemaphore()
{
    delete ui;
}

void mysemaphore::on_pushButton_clicked()
{
    m_thread->start();
}


void mysemaphore::deleteSlot()
{
    m_thread->wait();
    m_thread->deleteLater();
}

void mysemaphore::on_lineEdit_textChanged(const QString &arg1)
{
    m_thread->index = ui->lineEdit->text().toInt();
}


mythread::mythread() : m_semaphore(0),index(0)
{

}

void mythread::run()
{
    while(1)
    {
        //获取可用资源数量
        switch (index)
        {
        case 0:
            //获取一个资源
            m_semaphore.acquire();
            qDebug()<<"1--unlock--sem"<<m_semaphore.available()<<"---type=0";
            break;
        case 1:
            //获取2个资源
            m_semaphore.acquire(2);
            qDebug()<<"2--unlock--sem"<<m_semaphore.available()<<"---type=1";
            break;
        case 2:
            // 尝试获取资源
            if (m_semaphore.tryAcquire())
            {
                qDebug()<<"try--unlock--sem"<<m_semaphore.available()<<"---type=2";
            }
            break;
        case 3:
            // 尝试获取2个资源
            if (m_semaphore.tryAcquire(2))
            {
                qDebug()<<"try--unlock-2-sem"<<m_semaphore.available()<<"---type=3";
            }
            break;
        case 4:
            // 控制多个条件
            m_semaphore.acquire();
            qDebug()<<"--unlock--1"<<m_semaphore.available()<<"---type=4";
            m_semaphore.release();//释放1个资源
            m_semaphore.acquire(2);
            qDebug()<<"--unlock--2"<<m_semaphore.available()<<"---type=4";
            m_semaphore.release(2);//释放2个资源
            m_semaphore.acquire(3);
            qDebug()<<"--unlock--3"<<m_semaphore.available()<<"---type=4";
            break;
        default:
            qDebug()<<"no exsit"<<m_semaphore.available();
            break;
        }
    }
}

void mythread::useSlot()
{
    qDebug()<<"click--";
    // 释放一个资源
    m_semaphore.release();
}

结果如下：