Asynchronous TcpServer Share Object between Threads

buggi

Hello everyone,
I have a TcpServer up and running. As soon as a client connects I create a new socket and when the client is ready, I start my new Thread with the Task I want it to do. Now when I am ready executing and want to write my Task-result to the socket I have to work with Signal&Slots to make the Socket-Thread send my result. But what I want to do is, send the result directly from the Task-Thread. I tried passing the pointer to the socket to the Result-Thread and write to it, but this only gives me a Warning on runtime: QObject: Cannot create children for a parent that is in a different thread. (Parent is QNativeSocketEngine(0x11d7b10), parent's thread is QThread(0xfa9f40), current thread is QThread(0x101cac0). So maybe you can help me avoid Signals&Slots here.

So this is the Method for creating the Socket:
@
void MyClient::CreatSocket(qintptr handle)
{
socket = new QTcpSocket(this);

socket->setSocketDescriptor(handle);

connect(socket, SIGNAL(connected()), this, SLOT(connected()));
connect(socket, SIGNAL(disconnected()), this, SLOT(disconnected()));
connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()));

}
@

and here I create the new Task as soon as the Client is ready, and give it the socket.
@
void MyClient::readyRead()
{
task = new MyTask();
task->setAutoDelete (true);

task->SetSocket(socket);
task->SetFilename(FileName);

QThreadPool::globalInstance()->start(task);

}
@

This is the Set Socket Function:
@
void MyTask::SetSocket(QTcpSocket *socket)
{
socket = socket;
}
@

and last but not least the run Method of MyTask:
@
void MyTask::run()
{
QString non = "This is Sparta!!!!";

if(socket->isWritable())
{
    int written = socket->write(non.toUtf8());
    if(written == -1)
    {
        qWarning() << "Data could not be written to Socket!";
    }
    else
    {
        qDebug()<<"Non written to Socket";
    }
}
else
{
    qWarning() << "Socket is not writable!";
}

@

Thank you in advance! :)

t3685

You cannot read/write with a QTcpSocket in another thread than the one that created the Object.

Is there a reason why you want to write from the other thread, because

@QTcpSocket::write@

returns immediately causing no delay in your application.

buggi

Thanks for your reply!
Yes the reason is I'm lazy ;) In my Task-Thread I look at what the Client send me and check if he wants something back, when he wants something I have to send it like here:
"tmp" is the string I get from the socket/client.

@
if(tmp.contains("newcycle"))
{
tmp = tmp.replace("newcycle;","\n");
WriteData(tmp);
}
else if (tmp.contains("write"))
{
tmp = tmp.replace("write,","");
WriteData(tmp);
}
else if (tmp.contains("get_x_pos"))
{
emit send_x_pos();
}
else if(tmp.contains("get_y_pos"))
{
emit send_y_pos();
}
else if(tmp.contains("get_z_pos"))
{
emit send_z_pos();
}
@

And I have a huge amount of these "get_something" and "set_something"
and for every command I want to receive from the client I have to implement a Signal&Slot. Would make live much easier if I could send back the data right in the Task-Thread instead of emitting the signal.

And I am open for a complete redesign of my mechanism if that would make adding these "If(tmp.contains(...))" easy:D

dheerendra

Try changing the ownership of serversocket. I have not tried this. It should work. You can use myObject->moveToThread(...)

buggi

Ok so I do it like this:
@socket->moveToThread(...)@

my Problem is when I start the Thread like this:
@ QThreadPool::globalInstance()->start(task);@

how do I find out what Thread I have to move the socket to?

t3685

You could simply make one slot

@void sendData(QString)@

and one signal

@void dataReady(QString)@

and in your worker, determine what the string needs to be and emit dataReady.

[quote author="buggi" date="1390469097"]Thanks for your reply!
Yes the reason is I'm lazy ;) In my Task-Thread I look at what the Client send me and check if he wants something back, when he wants something I have to send it like here:
"tmp" is the string I get from the socket/client.

@
if(tmp.contains("newcycle"))
{
tmp = tmp.replace("newcycle;","\n");
WriteData(tmp);
}
else if (tmp.contains("write"))
{
tmp = tmp.replace("write,","");
WriteData(tmp);
}
else if (tmp.contains("get_x_pos"))
{
emit send_x_pos();
}
else if(tmp.contains("get_y_pos"))
{
emit send_y_pos();
}
else if(tmp.contains("get_z_pos"))
{
emit send_z_pos();
}
@

And I have a huge amount of these "get_something" and "set_something"
and for every command I want to receive from the client I have to implement a Signal&Slot. Would make live much easier if I could send back the data right in the Task-Thread instead of emitting the signal.

And I am open for a complete redesign of my mechanism if that would make adding these "If(tmp.contains(...))" easy:D[/quote]

buggi

Thank you for this response!
I had this Idea too and it looks like there is no better way to do it.

I will try it.