I am trying to modify the Qt Fortune Threaded Server example to read text from the connection and then echo it back. I defined tcpSocket in my FortuneThread.h file as follows:
QTcpSocket tcpSocket;
My new run function for the thread looks as follows:
void FortuneThread::run()
{
if (!tcpSocket.setSocketDescriptor(socketDescriptor)) {
emit error(tcpSocket.error());
return;
}
connect(&tcpSocket, SIGNAL(readyREAD()), this, SLOT(readCommand()) );
}
Which compiles and runs, but once I connect I get this error (referring to the connect line):
QObject: Cannot create children for a parent that is in a different thread.
(Parent is QTcpSocket(0x1eeb920), parent's thread is QThread(0x1bb3f90), current thread is FortuneThread(0x1eeb8f0)
QObject::connect: No such signal QTcpSocket::readyREAD() in ../fortune/fortunethread.cpp:60
Can someone explain the cause to me? Since tcpSocket is defined inside the FortuneThread class (which is run as a separate thread), and "this" refers to FortuneThread, I assume both objects are inside the thread? How to fix this?
Your socket object has been created in the main thread, but you're accessing it from a different thread. You need to create it inside of the thread's run() method. The location where the socket is defined doesn't matter. It will be created from the main thread when the C++ runtime library is doing static object initialization.
QTcpSocket * tcpSocket;
...
void FortuneThread::run() {
tcpSocket = new QTcpSocket;
...
}