QTcpSocket doesn't emit the signal ReadyRead()

Dooham

Hello,
Few days ago I have a trouble implementing a MultiClient Server, but finally I could solve my trouble (here is the link for the previous thread:https://forum.qt.io/topic/101298/qsocketnotifier-socket-notifiers-cannot-be-enabled-or-disabled-from-another-thread/23)
However, since I found the solution, I have been having other trouble: My goal is implenting a code for a Multiclient server that can read the messages from a device (A Pixhawk, is a device that is continously sending messages in form of package). With these messages group in form of QByteArray, I send this QbyteArray to my clients (programs that can decode the message and extract the information that the Pixhawk is trying to transmit). However I need to implement otrher function: i need to send a message from my client to the Pixhawk.
I made a client code that I know it can send and receive messages from a server (I prove it with a server code that I made and just can handle one connection and it also works with a multiclient server with the error that I had), so I think the trouble is in the solution that I found for my Server code.
This is my code (it's a bit different that the code from my previous thread):

server.cpp

#include "myserver.h"


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

}

void MyServer::startServer()
{
    if(!this->listen(QHostAddress::Any, 9999)){
qDebug()<<"Server not started";
    }else {
qDebug()<<"Server listening";
    }
}

void MyServer::startSerialPort()
{
   mipuerto2 = new MySerialPort;
  connect(mipuerto2, SIGNAL(msgChanged(QByteArray*)), this, SLOT(getMens(QByteArray*)));
   mipuerto2->openSerialPort();
}

void MyServer::getMens(QByteArray*array)
{



    emit mensChanged(array);
}

void MyServer::sendMens(QByteArray *arraySend)
{
mipuerto2->writeMsg(*arraySend);
}


void MyServer::incomingConnection(int socketDescriptor)
{

qDebug()<<socketDescriptor<<"Connecting... ";

socket = new MySocket(socketDescriptor);
QThread *thread = new QThread;
qDebug()<<thread->currentThreadId();
connect(this, SIGNAL(mensChanged(QByteArray*)), socket, SLOT(getMsg(QByteArray*)));

connect(socket, SIGNAL(mensajeEnviarSocket(QByteArray*)), this, SLOT(sendMens(QByteArray*)));
connect(socket, SIGNAL(disconnected()),thread, SLOT(quit()) );
connect(socket, SIGNAL(disconnected()), socket, SLOT(deleteLater()));
connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
connect(thread, SIGNAL(started()), socket, SLOT(funcionamiento()));

socket->moveToThread(thread);
thread->start();



}

mysocket.cpp

#include "mysocket.h"

MySocket::MySocket(int socketDescriptor)
{
ID=socketDescriptor;
}

void MySocket::leerMsg()
{
    qDebug()<<"Mensaje entrante";
    msgSend="";
   socket->waitForReadyRead(100);
    msgSend=socket->readAll();

    qDebug()<<msgSend.toHex();
    emit mensajeEnviarSocket(&msgSend);
}

void MySocket::funcionamiento()
{
    socket= new QTcpSocket;
    estado=socket->setSocketDescriptor(ID, QAbstractSocket::ConnectedState, QIODevice::ReadWrite);
    connect(this, SIGNAL(disconnected()), this, SLOT(desconexion()));
    connect(this, SIGNAL(readyRead()), this, SLOT(leerMsg()));
    qDebug()<<"Hola";
}

void MySocket::desconexion()
{
   socket->close();
   socket->deleteLater();
}

void MySocket::getMsg(QByteArray *array)
{
if(socket->waitForConnected(1000)){
    arr=*array;
    socket->write(arr);
    socket->flush();
    socket->waitForBytesWritten(3000);
}
}

I know that the troble is that the signal ReadyRead() is not emitted when I receive a new package of data from the client. As I said, I know that the client send the messages propertly; so I think that the trouble is with the class MySocket that don't work propertly. I have been the last hourse trying to find a solution.

koahnig

@Dooham said in QTcpSocket doesn't emit the signal ReadyRead():

void MySocket::funcionamiento()
{
socket= new QTcpSocket;
estado=socket->setSocketDescriptor(ID, QAbstractSocket::ConnectedState, QIODevice::ReadWrite);
connect(this, SIGNAL(disconnected()), this, SLOT(desconexion()));
connect(this, SIGNAL(readyRead()), this, SLOT(leerMsg()));
qDebug()<<"Hola";
}

Your problem seems to be there.

The signal is not connected to its origin "socket", but the object hosting "socket". Probably you need to change to

 void MySocket::funcionamiento()
 {
     socket= new QTcpSocket;
     estado=socket->setSocketDescriptor(ID, QAbstractSocket::ConnectedState, QIODevice::ReadWrite);
     connect(socket, SIGNAL(disconnected()), this, SLOT(desconexion()));
     connect(socket, SIGNAL(readyRead()), this, SLOT(leerMsg()));
     qDebug()<<"Hola";
 }

You should check also the application's output (e.g. in pane Application Output of creator). There should be a message popping up that the connect failed.

Alternatively you can use the functor syntax for connect which is giving you an error message at building time.

 void MySocket::funcionamiento()
 {
     socket= new QTcpSocket;
     estado=socket->setSocketDescriptor(ID, QAbstractSocket::ConnectedState, QIODevice::ReadWrite);
     connect(socket, &QTcpSocket::disconnected, this, &MySocket::desconexion);
     connect(socket, &QTcpSocket::readyRead, this, &MySocket::leerMsg);
     qDebug()<<"Hola";
 }

When you try the latter syntax with "this" instead of socket you will see immediately the effect e.g.

     connect(this, &QTcpSocket::disconnected, this, &MySocket::desconexion);
     connect(this, &QTcpSocket::readyRead, this, &MySocket::leerMsg);

Dooham

@koahnig You were right, changing the pointer this to socket in the connection function of readyRead, it worked. Thanks you