QThread Signal Not Received By Main Thread Slot

[EF2008]

I'm having a rather strange problem, and I'm wondering if anyone can help set me on track.

I'm new to working with QThreads, and I'm quite sure that this is a logic problem more than anything else.

I can't seem to connect my thread's custom signal to the desired slot on the main thread that launched it.

"mythread.h"

#include <QtGui>
class MyThread: public QThread
{
    Q_OBJECT
public:
    MyThread(int thread_id)
    {
        connect(this, SIGNAL(threadFinished(int)), this, SLOT(finished(int)),Qt::DirectConnection);
    }
    ~MyThread();
 
signals:
    void threadFinished(int thread_id);
 
public slots:
    void finished(int)
    {
        qDebug() << "finished(int) received in thread"; // output displays this
    }
 
protected:
    void run()
    {
        runGeneralQuery();
        runProgramNameQuery();
 
        emit threadFinished(thread_id);
    }
 
private:
    void runGeneralQuery(){};
    void runProgramNameQuery(){};
 
};

#include <QtGui>
class MyThread: public QThread
{
    Q_OBJECT
public:
    MyThread(int thread_id)
    {
        connect(this, SIGNAL(threadFinished(int)), this, SLOT(finished(int)),Qt::DirectConnection);
    }
    ~MyThread();

signals:
    void threadFinished(int thread_id);

public slots:
    void finished(int)
    {
        qDebug() << "finished(int) received in thread"; // output displays this
    }

protected:
    void run()
    {
        runGeneralQuery();
        runProgramNameQuery();

        emit threadFinished(thread_id);
    }

private:
    void runGeneralQuery(){};
    void runProgramNameQuery(){};

};

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"threadmanager.h"

#include <QtGui>
#include "mythread.h"
 
class ThreadManager: public QObject
{
    Q_OBJECT
public:
    ThreadManager()
    {
        /*...*/
        runThreads();
     }
 
 
    void runThreads()
    {
        thread= new MyThread(0);
        connect(thread, SIGNAL(threadFinished(int)), this, SLOT(finished(int)), Qt::DirectConnection);
 
        thread->start();
 
    }
 
 
public slots:
    void finished(int thread_id)
    {
        qDebug() << "finished(int) received in manager"; // output does not display this
    }
 
private:
    MyThread* thread;
 
};

#include <QtGui>
#include "mythread.h"

class ThreadManager: public QObject
{
    Q_OBJECT
public:
    ThreadManager()
    {
        /*...*/
        runThreads();
     }


    void runThreads()
    {
        thread= new MyThread(0);
        connect(thread, SIGNAL(threadFinished(int)), this, SLOT(finished(int)), Qt::DirectConnection);

        thread->start();

    }


public slots:
    void finished(int thread_id)
    {
        qDebug() << "finished(int) received in manager"; // output does not display this
    }

private:
    MyThread* thread;

};

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Does anyone have any suggestions as to why the signal isn't being received by the slot on the main thread?

Thanks in advance!

[tbscope]

What happens if you remove Qt::DirectConnection ?

[squidge]

You can't use DirectConnection with threads, they must be queued.

[EF2008]

No change, unfortunately.

[squidge]

Where do you run the event loop for the thread?

[EF2008]

Is executing the thread's event loop necessary for what I'm doing? I just need work to be done in MyThread::run(), have it emit a signal, and return...

[squidge]

It shouldn't be necessary tbh, just a stab in the dark.

What happens when you step through the run method?

[wysota]

Let's make one thing clear - you are not making connections across threads. QThread objects live in the main thread (at least in your situation).