#QTHREAD

[nam_anlab]

Hi everyone, i have a game mulitithread application, a server and many clients.
In Server Program, i creat 2 class. First class- mythread, and other -my server.
In mythread class, i have some functions, and slots to receive, send and bla. In my server class, i have a mythread list to append any creatated thread. Now, i want to send data from myserver to client; some things like this:
for(int i = 0; i < m_threadList.size(); i++)
{
m_threadList.at(i)->sendToClient(m_threadList.at(i)->getClients().at(i),"hello");
}

and i have receive this error:
@
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
ASSERT failure in QCoreApplication::sendEvent: "Cannot send events to objects owned by a different thread. Current thread 0x0x28799d30. Receiver '' (of type 'QNativeSocketEngine') was created in thread 0x0x3e791be0", file kernel\qcoreapplication.cpp, line 577
@

how do i fix this ? please help me!
sorry for my english!

//your code here
//here is myThread.h

class MyThread : public QThread
{
    Q_OBJECT
public:
    explicit MyThread(qintptr ID, QObject *parent = nullptr);

    void run();

signals:
    void error(QTcpSocket::SocketError socketerror);
    void checkOK();
public:
    QList<QTcpSocket *> getClients(); //  returnn socket  list
public slots:
   void readyRead();
   void disconnected();
   void sendQuestions(); // send questions
   qint64 sendToClient(QTcpSocket *socket, const QString &str);

private:
    qintptr socketDescriptor;
    QList<QTcpSocket*> connections;  
    QTcpSocket *socket;

and here is mythread.cpp

//your code here
MyThread::MyThread(qintptr ID, QObject *parent) :
    QThread(parent)
{
    this->socketDescriptor = ID;
}

void MyThread::run()
{
    qDebug() << "thread run :" << QThread ::currentThread();
    // thread starts here
    qDebug() << " Thread started";
    socket = new QTcpSocket();

    // set the ID
    if(!socket->setSocketDescriptor(this->socketDescriptor))
    {
        // something's wrong, we just emit a signal
        emit error(socket->error());
        return;
    }
    else
    {
    connections.append(socket);
    }
  //  m_demo = connections;

    // connect socket and signal
    connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()), Qt::DirectConnection);
    connect(socket, SIGNAL(disconnected()), this, SLOT(disconnected()));

    qDebug() << socketDescriptor << " Client connected";
    exec();

}

void MyThread::disconnected()
{
    qDebug() << socketDescriptor << " Disconnected";
    socket->deleteLater();
    exit(0);

}

void MyThread ::readyRead()
{

    QByteArray arrBlock = socket->readAll();
    QDataStream out(&arrBlock, QIODevice::ReadOnly);
    QString rec;

    out >> rec;
    qDebug() << rec;

}

QList<QTcpSocket *> MyThread::getClients()
{
    qDebug() << "clients thread :" << QThread ::currentThread();
    return connections;
}

void MyThread :: sendQuestions()
{
    int temp = 0;
    // doc file cau hoi
    QTextStream out(stdout);
    QFile file("E:/Visual/ANLab/Client-Server(Game)/server/question.txt");
     if (!file.open(QIODevice::ReadOnly)) {
       qWarning("Cannot open file for reading");
       return ;
     }
   //  QTextStream in(&file);
     QTextStream m_in(&file);
     while (!m_in.atEnd())
     {
         int i =0 ;
         temp++;
         QString line = m_in.readLine();

         // gui den tat ca cac client cac cau hoi
        for( i = 0;i < connections.size() ; i++)
        {
            sendToClient( connections.at(i), (qPrintable(line)) );// chuyen doi kieu QString ve const char
         }
       }
      file.close();
}

qint64 MyThread::sendToClient(QTcpSocket *socket, const QString &str)
{
    QByteArray arrBlock;
    QDataStream out(&arrBlock, QIODevice::WriteOnly);
    out << quint16(0) << str;

    out.device()->seek(0);
    out << quint16(arrBlock.size() - sizeof(quint16));

    return socket->write(arrBlock);
}

here is my server.h

//your code here
#ifndef MYSERVER_H
#define MYSERVER_H


#include <QTcpServer>
#include "mythread.h"

class MyServer : public QTcpServer
{
    Q_OBJECT
public:
    explicit MyServer(QObject *parent = nullptr);
    void startServer();


signals:
    void checkOK();

public slots:
    void incomingConnection(qintptr socketDescriptor);
    //-----------BO SUNG---------------//
    void update();



private:
  int m_person = 3 ; // so luong nguoi choi toi da doc tu file config
  int count = 0; // dem so nguoi choi thuc tai
  int flag = 1; // bien co danh dau de ket thuc su gui dem thoi gian nguoc
  int m_time = 1;
  QTime time; //  lay thoi gian troi qua
  QTimer *timer;// thuc hien interval gui thoi gian dem nguoc ve cho nguoi dung sau moi 5s
  QList <MyThread*> m_threadList;

};

#endif // MYSERVER_H

and the last myserver.cpp file

//your code here
#include "myserver.h"
#include "mythread.h"

MyServer::MyServer (QObject *parent) :
QTcpServer(parent)
{

}

void MyServer::startServer()
{
qDebug() << "startServer :" << QThread::currentThreadId();
int port = 6547;

if(!this->listen(QHostAddress::Any,port))
{
    qDebug() << "Could not start server";
}
else
{
    qDebug() << "Listening to port " << port << "...";
}

// send time clients
time.start();
timer = new QTimer();
connect(timer, SIGNAL(timeout()),this, SLOT(update()));
timer->start(5000);

}

void MyServer::incomingConnection(qintptr socketDescriptor)
{
count += 1;
// We have a new connection
qDebug() << socketDescriptor << " Connecting...";

MyThread *thread = new MyThread(socketDescriptor, this);
connect( thread, SIGNAL(finished()),thread, SLOT(deleteLater()) );
connect( this,  SIGNAL(checkOK()),thread, SLOT(sendQuestions()), Qt::DirectConnection );

if(count > m_person)
{

    thread->deleteLater();
}

else
{
    m_threadList.append(thread);
    thread->start();
}

}

void MyServer :: update()
{

if(  time.elapsed() > m_time*60000 || count == m_person )
{
    flag = 0;
    timer->stop();
    emit checkOK();

}

qDebug() << "thread update:" << QThread::currentThreadId();
    if(  flag == 1 )
    {
        for(int i = 0; i < m_threadList.size(); i++)
        {
           QByteArray tmp_m = QByteArray::number(m_time * 60 - time.elapsed() / 1000);


         // error here
           m_threadList.at(i)->sendToClient(m_threadList.at(i)->getClients().at(i),"hello");
         
        }

 }

}

[sierdzio]

I don't have time to analyse your whole code, but I think the bad bit can be in MyThread :: sendQuestions(). That method is not executed in MyThread::run so it most likely gets executed in main thread (the thread in which MyThread object was created), and not your thread (the thread inside run()). You can check if this->thread() is the same in run() and in sendQuestions() to be sure.

I strongly suggest using the worker thread pattern - see QThread documentation.

[aha_1980]

@nam_anlab

or just to add to @sierdzio: avoid threads.

For your simple example they are most likely not needed.

A server can handle dozens of clients in a single thread, if it works asynchronous, like Qt servers do.

[nam_anlab]

@sierdzio i think so, thank you so much !