QT multi-thread socket quit issue

gaosiy

As title, I made a project to use multi-thread realize multi-socket client connection.
I choose 'move to a thread' to make my data processing in the new thread.
I test it works, "thread over " can be print
My question is are there any risks, or how can I know the tread is over?

//server.cpp
void Server::incomingConnection(qintptr socketDescriptor)
{

    qDebug()<<"incoming in thread: "<<QThread::currentThreadId();

    Thread *thread = new Thread(socketDescriptor,this);
    Worker *cpu=new Worker(thread->socket);
    connect(thread->socket,SIGNAL(readyRead()),cpu,SLOT(socket_Read_Data()));
    connect(thread->socket, SIGNAL(disconnected()), cpu, SLOT(socket_Disconnected()));
    connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
    connect(thread, SIGNAL(finished()), this, SLOT(Over()));
    cpu->moveToThread (thread);
    cpu->socket->moveToThread(thread);
    thread->start();
}
void Server::Over()
{
    qDebug()<<"thread over!";
}

in server.cpp I overwriter the incommingconnection function, and connect 2 slot and signal. I want to realize that when socket is disconnected, the thread should be quit and release all the resource.

this is worker.cpp

//worker.cpp
void Worker::socket_Read_Data()
{
//data processing
}

void Worker::socket_Disconnected()
{

   this->thread()->quit();
   this->thread()->wait();

}

Christian Ehrlicher

This doesn't work at all. QThread is not a thread but an object which creates a thread. All stuff inside QThread::run() is running in another thread. Therefore when you create your QTcpSocket inside Thread's ctor it will be created in the main thread.
The easiest way to go is

QThread *t = new QThread(this);
Worker *w = new Worker(socketDescriptor); // no parent - otherwise moveToThread will not work, see documentation!
connect(t, &QThread::started, w, &Worker::doWork);
connect(...)
w->moveToThread(t);
t->start();

~~The Worker is started in the~~

gaosiy

tks a lot.
have you finished the answer? I find the last sentences is ‘the worker is started in the’

by the way, how can I finish the thread when the socket is disconnected.

tks again.

KillerSmath

@gaosiy

Assuming that Worker has Socket instead of is Socket (relationship).
You can forward the socket disconnected signal to a worker signal to stop the thread

 // in worker and thread creation
 connect(t, &QThread::finished, w, &Worker::deleteLater);
 connect(t, &QThread::finished, t, &QThread::deleteLater);
 connect(w, &Worker::socketDisconnected, t, &QThread::quit);

// in worker constructor
connect(mySocket, &QTcpSocket::disconnected, this, &Worker::socketDisconnected); // worker signal

Or use a slot function from your worker to stop its thread.

// in worker and thread creation
 connect(t, &QThread::finished, w, &Worker::deleteLater);
 connect(t, &QThread::finished, t, &QThread::deleteLater);

// in worker constructor
connect(mySocket, &QTcpSocket::disconnected, this, &Worker::onSocketDisconnected); // worker slot

// worker onSocketDisconnected Slot function
void Worker::onSocketDisconnected()
{
    this->thread()->quit();
}

gaosiy

@KillerSmath
tks, it all works, so do my code above.
I think I find the original question, that is QTcpSocket::disconnected cant be emitted in some cases.
When I use software to connect my server and disconnect it, QTcpSocket::disconnected can be emitted.
When I use my two network hardware to connect, one of them cant make the QTcpSocket::disconnected work when I shut down the hardware, another one can make the QTcpSocket::disconnected work when I shut down, but it works after 10 seconds, it's very strange and confused me.
I will find why and how to check the connection state and use another way to deal with the disconnection issue.

tks again KillerSmath, you are so warmhearted!