c++qtqt5qtcpsocket

How can I connect QtcpSockets to about 100 servers without a UI hang?


How can I connect QtcpSockets to about 100 servers without a UI hang?

When I create 100 QTcpSockets to connect to each server and call the connectToHost() function, the QDialog stuck. Is there a way to run the connectToHost() part as a background job?

As a result, all connections are made, but while trying to connect (call connectToHost() the UI is in 'No Response' state.

// onConnectToICPMC is the slot function connected to the dialog button pressed signal
void WidgetUploadFile::onConnectToICPMC()
{
    // m_tcpClients is a QVector containing a custm QObject Class that manages QTcpSocket
    for(int i = 0; i < m_tcpClients.size(); ++i)
    {
        if(m_tcpClients.at(i)->state() != QAbstractSocket::ConnectedState)
        {
            m_tcpClients.at(i)->connectToServer(); // Call the connectToHost() function of QTcpSocket.
        }
        emit sendConnProgBarUpdate(i+1);
        emit sendCurrentSockLog(m_tcpClients.at(i)->ipAddress(), m_tcpClients.at(i)->state());
    }
}

A dialog that hangs while each QTcpSocket connects to the server.:
A dialog that hangs while each QTcpSocket connects to the server.

After all QTcpSockets try to connect to the server:
After all QTcpSockets try to connect to the server


Solution

  • Time-consuming tasks should not be run on the main thread. In that case there are 2 strategies:

    In this case I think the second option is the best using QTimeLine.

    *.h

    private:
       void handleFrameChanged(int i);
       QTimeLine timeLine;
    

    *.cpp

    {
        // constructor
        timeLine.setRange(0, m_tcpClients.size()-1);
        connect(&timeLine, &QTimeLine::frameChanged, this, &WidgetUploadFile::handleFrameChanged);
    }
    
    void WidgetUploadFile::onConnectToICPMC()
    {
        timeLine.start();
    }
    
    void WidgetUploadFile::handleFrameChanged(int i){
        auto client = m_tcpClients.at(i);
        if(client->state() != QAbstractSocket::ConnectedState){
            client->connectToServer();
        }       
        emit sendConnProgBarUpdate(i + 1);
        emit sendConnProgBarUpdate(client->ipAddress(), client->state());
    }