详细了解Thread Affinity与跨线程信号槽

来源：互联网发布：flux软件怎么恢复编辑：程序博客网时间：2024/05/31 19:12

本篇介绍详细了解Thread Affinity与跨线程信号槽，QObject的线程依附性（thread affinity）是指某个对象的生命周期依附的线程（该对象生存在该线程里）。我们在任何时间都可以通过调用QObject::thread()来查询线程依附性，它适用于构建在QThread对象构造函数的对象。

// file multiSignal.h     
#ifndef MULTISIGNAL_H     
#define MULTISIGNAL_H     
#include <QThread>     
class Thread : public QThread     
{     
Q_OBJECT     
signals:     
    void aSignal();     
protected:     
    void run();     
};     
class Object: public QObject     
{     
Q_OBJECT     
   public slots:     
     void aSlot();     
};     
#endif // MULTISIGNAL_H    
// file multiSignal.h  
#ifndef MULTISIGNAL_H  
#define MULTISIGNAL_H  
#include <QThread> 
class Thread : public QThread  
{  
Q_OBJECT  
signals:  
    void aSignal();  
protected:  
    void run();  
};  
class Object: public QObject  
{  
Q_OBJECT  
   public slots:  
     void aSlot();  
};  
#endif // MULTISIGNAL_H  
   
 
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#include <QtCore/QCoreApplication>     
#include <QDebug>     
#include <QTimer>     
#include "multiSignal.h"     
void Object::aSlot()     
{     
   QTimer *timer = new QTimer;     
   qDebug()<< "aSlot " << timer->thread();     
   qDebug() << "aSlot called";     
   delete timer;     
}     
void Thread::run()     
{     
   QTimer *timer = new QTimer;     
   qDebug()<< "run " << timer->thread();     
   emit aSignal();     
   delete timer;     
}     
int main(int argc, char *argv[])     
{     
    QCoreApplication a(argc, argv);     
    Thread thread;     
    Object obj;     
    qDebug()<< "mainThread " << a.thread();     
    qDebug()<< "thread " << thread.thread();     
    qDebug()<< "Object " << obj.thread();     
    QObject::connect(&thread, SIGNAL(aSignal()), &obj, SLOT(aSlot()));     
    thread.start();     
    return a.exec();     
}    
#include <QtCore/QCoreApplication> 
#include <QDebug> 
#include <QTimer> 
#include "multiSignal.h"  
void Object::aSlot()  
{  
   QTimer *timer = new QTimer;  
   qDebug()<< "aSlot " << timer->thread();  
   qDebug() << "aSlot called";  
   delete timer;  
}  
void Thread::run()  
{  
   QTimer *timer = new QTimer;  
   qDebug()<< "run " << timer->thread();  
   emit aSignal();  
   delete timer;  
}  
int main(int argc, char *argv[])  
{  
    QCoreApplication a(argc, argv);  
    Thread thread;  
    Object obj;  
    qDebug()<< "mainThread " << a.thread();  
    qDebug()<< "thread " << thread.thread();  
    qDebug()<< "Object " << obj.thread();  
    QObject::connect(&thread, SIGNAL(aSignal()), &obj, SLOT(aSlot()));  
    thread.start();  
    return a.exec();  
}

打印结果：

Debugging starts   
mainThread QThread(0x3e2870)   
thread QThread(0x3e2870)   
Object QThread(0x3e2870)   
run Thread(0x22ff1c)   
aSlot QThread(0x3e2870)   
aSlot called

我们知道跨线程的信号槽连接需要使用queued connection，上述代码中QObject::connect(&thread, SIGNAL(aSignal()), &obj, SLOT(aSlot())); 虽然thread与obj的线程依附性相同，它们都隶属于地址为0x3e2870的线程；但是我们看到发射aSignal的线程

与之不同是0x22ff1c. 这就是为什么使用queued connection。

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