QtConcurrent::run() with virtual function

[Mihan]

Hi all

I want to make a abstract class to process data from different IO devices.

I have an idea as follow:

class AbstractCommunication : public QObject
{
    Q_OBJECT
public:
    QMutex m_CacheMutex;       
    QByteArray m_receiveCache;  

public:
    explicit AbstractCommunication(QIODevice *device);
    void sendData(QByteArray data);

    int receiveTick() const;

private:
    virtual void processPacket();

private slots:
    void receiveData();

private:
    QIODevice *m_communication;
    int m_receiveTick;         
};

AbstractCommunication::AbstractCommunication(QIODevice *device) :
    m_communication(device)
{
    m_receiveCache.clear();
    if(m_communication->isOpen())
    {
        connect(m_communication,SIGNAL(readyRead()),this,SLOT(receiveData()));
        QtConcurrent::run(this,&AbstractCommunication::processPacket);
    }
    else
    {
        qDebug()<<"device is not ready";
    }
}

void AbstractCommunication::sendData(QByteArray data)
{
    m_communication->write(data);
}

void AbstractCommunication::receiveData()
{
    QMutexLocker lock(&m_CacheMutex);
    
    m_receiveCache.append(m_communication->readAll());
    
    m_receiveTick = (m_receiveTick + 1) % MAX_RECEIVE_TICK;  

    // then process the data with the same protocol
    
    
}

nt AbstractCommunication::receiveTick() const
{
    return m_receiveTick;
}

// this virtual function will be overwrite in different module, which inherit this class.
void AbstractCommunication::processPacket()
{
    qDebug()<<"in virtual thread".
}

first it doesn't work. then I improve the max count of thread pool QThreadPool::globalInstance()->setMaxThreadCount(8);,
sometimes it works, but sometimes it only print "in virtual thread".'

does the pointer this mean this abstract class , not the class inheriting it?

Best regards
Mihan

[VRonin]

I think it's more the fact that you are passing a pointer to the base class method. Try:
QtConcurrent::run([this](){processPacket();});

P.S.
Using QtConcurrent here is unsafe, this could get deleted/go out of scope while processPacket() is still running

[KroMignon]

@Mihan said in QtConcurrent::run() with virtual function:

QtConcurrent::run(this,&AbstractCommunication::processPacket);

Why do you do this in base class constructor?
This will call AbstractCommunication::processPacket() and not any overload... So no need to made it virtual!

[Mihan]

Sorry for late and thanks a lot @VRonin @KroMignon

I modified it according to your suggestions, now it works well!