Loop running with Qt running on side

TimeStrecher

Hello everyone,
I am on a small project and I ran into a problem. I need to run a for loop for the server to liste to new connections. Qt app will either freeze or stop being active until the loop is done. But I need both to run at the same time. I tried with threads, but the thread makes the app crash unless I call thread.join() which will make the app freeze until the thread is finish. So I'm stuck and I have no idea how to proceed. Thanks for the help and here is the project.

#include "serveur.h"


Server::Server(int PORT, bool broadcastPublic = false): QWidget()
{
	WSADATA wsaData;
	WORD dllVersion = MAKEWORD(2, 1);
    Window();

	if (WSAStartup(dllVersion, &wsaData) != 0)//starting winsock and check sucessfull startup
	{
        QMessageBox::critical(this, "Error", "Winsock Startup Failed");
		exit(1);
	}

	if (broadcastPublic == true)//check if server open to public
	{
		m_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	}
	else//server open to local only
	{
		m_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
	}

	m_addr.sin_port = htons(PORT);//port used
	m_addr.sin_family = AF_INET;//get IPv4 connections
	m_sockListen = socket(AF_INET, SOCK_STREAM, NULL);//creating listening socket

	if (bind(m_sockListen, (SOCKADDR*)&m_addr, sizeof(m_addr)) == SOCKET_ERROR)//bind the port to socket
	{
        QString errorMsg = QStringLiteral("Failed to bind to our listening port. Winsock error: %1").arg(WSAGetLastError());
        QMessageBox::critical(this, "Error", errorMsg);
		exit(1);
	}

	if (listen(m_sockListen, SOMAXCONN) == SOCKET_ERROR)
	{
        QString errorMsg = QStringLiteral("Listening socket failed. Winsock error: %1").arg(WSAGetLastError()) ;
        QMessageBox::critical(this, "Error", errorMsg);
		exit(1);
	}

	serverPtr = this;
}

void Server::Window()//setting up the interface
{
    setFixedSize(600, 400);

    m_start = new QPushButton("Start Server");
    m_shut  = new QPushButton("Shut Down");
    QTextEdit *log = new QTextEdit;

    log->setReadOnly(true);
    log->setFont(QFont("Courier"));
    log->setLineWrapMode(QTextEdit::NoWrap);

    QHBoxLayout *footer = new QHBoxLayout();
    footer->addWidget(m_start);
    footer->addWidget(m_shut);

    QGridLayout *window = new QGridLayout();
    window->addWidget(log, 0, 1);
    window->addLayout(footer, 1, 0, 1, 2);

    setLayout(window);

    //QObject::connect(m_start, SIGNAL(clicked()), this, SLOT(ServerLaunch()));
    QObject::connect(m_shut, SIGNAL(clicked()), this, SLOT(close()));

}

bool Server::ListenNewConnections()//method i call in loop
{
    SOCKET newConnection = accept(m_sockListen, (SOCKADDR*)&m_addr, &m_addrSize);

    if (newConnection == 0)
    {
        std::clog << "Failed to accept the client's connection." << std::endl;
        return false;
    }
    else
    {
        std::clog << "Client Connected! ID:" << m_totalConnections << std::endl;
        m_connections[m_totalConnections].socket = newConnection;
        CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)ClientHandlerThread, (LPVOID)(m_totalConnections), NULL, NULL);
        m_totalConnections += 1;
        return true;
    }
}

void Server::ClientHandlerThread(int ID)
{
	PacketType _packetType;
	while (true)
	{
		if (!serverPtr->GetPacketType(ID, _packetType)) //Get packet type
			break; //If there is an issue getting the packet type, exit this loop
		
		if (!serverPtr->ProcessPacket(ID,_packetType))
			break; //If there is an issue processing the packet, exit this loop
	}
	std::cout << "Lost connection to client ID: " << ID << std::endl;
	closesocket(serverPtr->m_connections[ID].socket);
}

Wieland

Hi! Using another thread was the right idea, but it shouldn't crash of course :-) Here's a guide on How To Really, Truly Use QThreads.

TimeStrecher

I still get the app not responding.

Server::Server(int PORT, bool broadcastPublic): QWidget()
{
    QThread *thread = new QThread;
    QObject::connect(thread, SIGNAL(started()), this, SLOT(ServerRunning()));
    thread->start();

	WSADATA wsaData;
	WORD dllVersion = MAKEWORD(2, 1);
    Window();

	if (WSAStartup(dllVersion, &wsaData) != 0)//starting winsock and check sucessfull startup
	{
        QMessageBox::critical(this, "Error", "Winsock Startup Failed");
		exit(1);
	}

	if (broadcastPublic == true)//check if server open to public
	{
		m_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	}
	else//server open to local only
	{
		m_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
	}

	m_addr.sin_port = htons(PORT);//port used
	m_addr.sin_family = AF_INET;//get IPv4 connections
	m_sockListen = socket(AF_INET, SOCK_STREAM, NULL);//creating listening socket

	if (bind(m_sockListen, (SOCKADDR*)&m_addr, sizeof(m_addr)) == SOCKET_ERROR)//bind the port to socket
	{
        QString errorMsg = QStringLiteral("Failed to bind to our listening port. Winsock error: %1").arg(WSAGetLastError());
        QMessageBox::critical(this, "Error", errorMsg);
		exit(1);
	}

	if (listen(m_sockListen, SOMAXCONN) == SOCKET_ERROR)
	{
        QString errorMsg = QStringLiteral("Listening socket failed. Winsock error: %1").arg(WSAGetLastError()) ;
        QMessageBox::critical(this, "Error", errorMsg);
		exit(1);
	}

	serverPtr = this;
}

void Server::ServerRunning()
{
    for (int i = 0; i < 100; i++)
    {
        ListenNewConnections();
    }
}

pip010

well you need 2 threads, one for the server but also 1 for the client. I can assume listen is blocking?
also are you mixing Qt and native code? why? why not use Qt connectivity instead of raw socket api?