QWebSocketServer and QThread

red_spider

Hello everyone. for some reasons, namely when a user fills a stream, others do not have access to the server,
I need to make separate threads on QWebSocket, so I know that QWebSocket cannot be passed to other threads, so I wrote an example in which QTcpServer -> socketDescriptor - > QThread -> QTcpSocket -> QWebSocketServer::handleConnection and accordingly via newConnection I get a QWebSocket,
the connection is established and the data is received by the server and can be processed, but when I try to send back to the client nothing happens except one error in the console,

QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread

here is a simple example server, tested from the standard echoclient example
if you do not transfer the work of QWebSocketServer to a heavy thread, then everything works.
maybe someone has some idea what the problem is, or has faced such before.

Thank you for attention.

example
main.cpp

#include <QCoreApplication>
#include "TcpServerMultithreading.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    TcpServerMultithreading serverTcp(1551);
    return a.exec();
}

TcpServerMultithreading.h

#ifndef TCPSERVERMULTITHREADING_H
#define TCPSERVERMULTITHREADING_H

#include <QObject>
#include <QTcpServer>

#include <QTcpSocket>
#include <QtWebSockets/QWebSocketServer>
#include <QtWebSockets/QWebSocket>

class TcpServerMultithreading : public QTcpServer
{
    Q_OBJECT
public:
    explicit TcpServerMultithreading(quint16 port, QObject *parent = nullptr);

protected:
    void incomingConnection(qintptr socketDescriptor) override;


public slots:
    void parseMessage(const QString &message);
    void onNewConnection();

private:
    int socketDescriptor;
    QWebSocketServer *m_pWebSocketServer;
};

#endif // TCPSERVERMULTITHREADING_H

TcpServerMultithreading.cpp

#include "TcpServerMultithreading.h"
#include "UserConnectThread.h"

TcpServerMultithreading::TcpServerMultithreading(quint16 port, QObject *parent)
    : QTcpServer{parent}
{
    if (listen(QHostAddress::Any, port))
    {
        qDebug() << "SSL Echo Server listening on port" << serverPort();
    }
    else
    {
        qDebug() << "ERROR: " << errorString();
    }
}

void TcpServerMultithreading::incomingConnection(qintptr socketDescriptor)
{
    qDebug() << Q_FUNC_INFO << socketDescriptor;

    UserConnectThread *userConnectThread = new UserConnectThread(socketDescriptor, this);


    userConnectThread->start();
}


void TcpServerMultithreading::parseMessage(const QString &message)
{
    qDebug() << Q_FUNC_INFO << message;

    QWebSocket *pClient = qobject_cast<QWebSocket *>(sender());

    pClient->sendTextMessage(QString("return: %1").arg(message));
}

void TcpServerMultithreading::onNewConnection()
{
    qDebug() << Q_FUNC_INFO;
    QWebSocket *m_pSocket = m_pWebSocketServer->nextPendingConnection();

    connect(m_pSocket, &QWebSocket::textMessageReceived, this, &TcpServerMultithreading::parseMessage);
}

UserConnectThread.h

#ifndef USERCONNECTTHREAD_H
#define USERCONNECTTHREAD_H

#include <QObject>
#include <QThread>
#include <QTcpSocket>
#include <QtWebSockets/QWebSocketServer>
#include <QtWebSockets/QWebSocket>

class UserConnectThread : public QThread
{
    Q_OBJECT
public:
    explicit UserConnectThread(int socketDescriptor, QObject *parent = nullptr);

    void run() override;
signals:
    void sendToClient(QString message);

public slots:
    void parseMessage(const QString &message);
    void onNewConnection();

private:
    int socketDescriptor;
    QWebSocketServer *m_pWebSocketServer;
};

#endif // USERCONNECTTHREAD_H

UserConnectThread.cpp

#include "UserConnectThread.h"

UserConnectThread::UserConnectThread(int socketDescriptor, QObject *parent)
    : QThread{parent}, socketDescriptor(socketDescriptor)
{

}

void UserConnectThread::run()
{
    qDebug() << "Run Thread";
    QTcpSocket *tcpSocket = new QTcpSocket();


    if (!tcpSocket->setSocketDescriptor(socketDescriptor)) {
        //emit error(tcpSocket->error());
        return;
    }

    m_pWebSocketServer = new QWebSocketServer(QStringLiteral("SSL Echo Server"),
                                              QWebSocketServer::NonSecureMode);


    connect(m_pWebSocketServer, &QWebSocketServer::newConnection,
            this, &UserConnectThread::onNewConnection);


    m_pWebSocketServer->handleConnection(tcpSocket);

    exec();
}

void UserConnectThread::parseMessage(const QString &message)
{
    qDebug() << Q_FUNC_INFO << message;

    QWebSocket *pClient = qobject_cast<QWebSocket *>(sender());

    int sizeSend = pClient->sendTextMessage(QString("return: %1").arg(message));
    qDebug() << Q_FUNC_INFO << "send: " << sizeSend;
}

void UserConnectThread::onNewConnection()
{
    qDebug() << Q_FUNC_INFO;
    QWebSocket *m_pSocket = m_pWebSocketServer->nextPendingConnection();

    connect(m_pSocket, &QWebSocket::textMessageReceived, this, &UserConnectThread::parseMessage);
    connect(this, &UserConnectThread::sendToClient, m_pSocket, &QWebSocket::sendTextMessage);
}

Christian Ehrlicher

@red_spider said in QWebSocketServer and QThread:

connect(m_pWebSocketServer, &QWebSocketServer::newConnection,
this, &UserConnectThread::onNewConnection);

Common error - since this is living in the main thread, the slot is executed there.
Ise the worker approach instead. But don't see why a thread is needed here at all though.

red_spider

@Christian-Ehrlicher thank you for your reply, it will solve my problem there.

distribution into separate streams, it is necessary because when you download a large stream of binary data through a socket, everyone else who has their own sockets does not receive a response, they wait until the data is loaded