Can't receive signal from another thread.

[useryy]

Can't receive signal from another thread as following.
Using connect type as Qt::BlockingQueuedConnection, the thread blocks. But signal not received.

main.cpp

#include "myclass.h"
 
 
 
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
 
    MyClass myClass;
    myClass.startAll();
 
    return a.exec();
}

#include "myclass.h"




int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);


    MyClass myClass;
    myClass.startAll();

    return a.exec();
}

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thread.h

#include <QtCore/QCoreApplication>
#include <QThread>
 
#include <QDebug>
 
 
 
class Thread1 : public QThread
{
    Q_OBJECT
public:
    void run( void )
    {
        qDebug() << "thread 1 started";
        int i = 0;
        while(1)
        {
           msleep( 10 );
           i++;
           qDebug() << "i is: " + QString::number(i);
           if(i==1000)
           {
               qDebug() << "Got I";
               emit MyThread1Signal();
               exit();
           }
        }
    }
signals:
    void MyThread1Signal();
};

#include <QtCore/QCoreApplication>
#include <QThread>

#include <QDebug>



class Thread1 : public QThread
{
    Q_OBJECT
public:
    void run( void )
    {
        qDebug() << "thread 1 started";
        int i = 0;
        while(1)
        {
           msleep( 10 );
           i++;
           qDebug() << "i is: " + QString::number(i);
           if(i==1000)
           {
               qDebug() << "Got I";
               emit MyThread1Signal();
               exit();
           }
        }
    }
signals:
    void MyThread1Signal();
};

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myclass.cpp

MyClass::MyClass(QObject *parent) :
    QObject(parent)
{
    thread1 = new Thread1();
    connect(thread1, SIGNAL(MyThread1Signal()), this, SLOT(myClassSlot1()), Qt::BlockingQueuedConnection);
}
 
 
void MyClass::startAll()
{
    thread1->start();
    thread1->wait();
}
 
 
void MyClass::myClassSlot1()
{
    qDebug()<<"Signal received";
}

MyClass::MyClass(QObject *parent) :
    QObject(parent)
{
    thread1 = new Thread1();
    connect(thread1, SIGNAL(MyThread1Signal()), this, SLOT(myClassSlot1()), Qt::BlockingQueuedConnection);
}


void MyClass::startAll()
{
    thread1->start();
    thread1->wait();
}


void MyClass::myClassSlot1()
{
    qDebug()<<"Signal received";
}

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myclass.h

#ifndef MYCLASS_H
#define MYCLASS_H
 
#include <QObject>
 
#include "threads.h"
 
class MyClass : public QObject
{
    Q_OBJECT
public:
    explicit MyClass(QObject *parent = 0);
 
    void startAll();
 
signals:
 
public slots:
    void myClassSlot1();
 
private:
    Thread1* thread1;
};
 
#endif // MYCLASS_H

#ifndef MYCLASS_H
#define MYCLASS_H

#include <QObject>

#include "threads.h"

class MyClass : public QObject
{
    Q_OBJECT
public:
    explicit MyClass(QObject *parent = 0);

    void startAll();

signals:

public slots:
    void myClassSlot1();

private:
    Thread1* thread1;
};

#endif // MYCLASS_H

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[Lesiok]

Because You never launch main event loop. Why wait for the end of the second thread in the method MyClass::startAll calling thread1->wait() ?

[useryy]

Hi,

For It needs not receive any event in thread, so I don't think exec() is required.


Remove wait(), it is ok. It's this wait() that makes the thread never give up execution. Right?

Please correct me if my understanding is wrong.

[Lesiok]

Yes, a problem is wait(). But I'm talking about main exec. You have a connection with attribute Qt::BlockingQueuedConnection. This means that the event is delivered through the recipient's message queue thread. This is not the same as Qt:: DirectConnection.