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

CP71

@Dooham
I have a dubt.
Maybe I’m beeing wrong but I think that your server musn't create TcpSocket but it should waiting a new connection:

In your server
QObject::connect( this, SIGNAL(newConnection()), this, SLOT(newConnection()) );

In newConnection:

//////////////////////////////////////////////////////////////////////////////////////
///
void MyServer::newConnection()
{
QTcpSocket *socket = server->nextPendingConnection();
if ( socket )
{
… doing your procedure
}
}

I don’t see where incomingConnection is called.

But maybe it is already so.

Dooham

@CP71 I think that is not neccesary,because of the function incomingConnection. When I see this Code I had a similar doubt, but this function is a virtual function of QtcpServer that is called when a newConnection Signal appears. In this code,I just edit the function a bit.
Maybe the trouble would be that I didnt called the write function from the run, and this could be problematic. In a while, I will try to rewrite the code un order to call the function that write the message from the run

SGaist

Hi,

Are you trying to implement a threaded server ? If so, you can take a look at the threaded fortune server example.

Dooham

@SGaist Thanks you, I think this example support my idea, that the trouble is that I dont call the function that write the message from the run function but from a external slot that, in theory dont interact with this routine. Am I right?
On the other hand, do you know any method to initialize the serial port from the thread just one time (at the begginning of the program)? I have been thinking during the last hour but I dont archive any progress
Thanks again

SGaist

What is your exact use of QSerialPort ?

Dooham

@SGaist I read the continuous message that a device (a Pixhawk). Every thing that I receive a package of message ( the serial port send me package of message) in form of QByteArray I send it to a client that can decode them

Dooham

@Dooham That didn't work, I dont know what is the trouble, I have seen that there are two different QThread ID, and that is probably the cause of the issue:
0_1554190211682_3c2ed1b3-b00e-4493-9839-8182529d1966-image.png
As you can see, I got the adress of the Thread that I generate with the incomingConnection but, in some point I create an Object that its parent is other QThread.
I dont know what to do.

CP71

@Dooham
I think you don't call addPendingConnection or it seems so

0_1554194144567_013b5385-d81d-4dd1-be58-d950d072f8e1-image.png

Dooham

@Dooham @CP71 @SGaist Finally I could "solve" the trouble that I had. I had to create other class that has the QTcpSocket, and create that class inside the run function of the thread as a local variable. However I found some trouble with the write method, I dont know how to solve it. The trouble is that dont read the client (with the previous code I could read, the messaged from the client). This is my code:

myserver.cpp

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... ";
MyThread *thread=new MyThread(socketDescriptor, this);

qDebug()<<thread;
connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
connect(this, SIGNAL(mensChanged(QByteArray * )), thread, SLOT(getMsg(QByteArray *)));
connect(thread, SIGNAL(mensajeEnviar(QByteArray * )), this,SLOT(sendMens(QByteArray * )));



thread->start();

}

myserialport.cpp

#include "myserialport.h"
#include <QObject>
#include <QtSerialPort/QSerialPort>
#include <QDebug>


MySerialPort::MySerialPort()
{
    serial = new QSerialPort(this);
    data= "";

    connect(serial, SIGNAL(readyRead()), this, SLOT(readData()));
    openSerialPort();

}

void MySerialPort::openSerialPort()
{
    serial->setPortName("COM4");
    //serial->setBaudRate(QSerialPort::Baud9600);
    serial->setBaudRate(QSerialPort::Baud115200);
    serial->setDataBits(QSerialPort::Data8);
    serial->setParity(QSerialPort::NoParity);
    serial->setStopBits(QSerialPort::OneStop);
    serial->setFlowControl(QSerialPort::NoFlowControl);
    serial->open(QIODevice::ReadWrite);


}

void MySerialPort::closeSerialPort()
{
    if(serial->isOpen()){
        serial->close();
    }
}

void MySerialPort::readData()
{

   data = serial->readAll();
    dataAux=data.toHex();
    emit msgChanged(&data);

}

QByteArray MySerialPort::getMensaje()
{
    return data;
}

void MySerialPort::writeMsg(QByteArray datos)
{

    serial->write(datos);

}

mythread.cpp

#include "mythread.h"
#include "mysocket.h"
MyThread::MyThread(int ID, QObject *parent) : QThread(parent)
{
    this->socketDescriptor=ID;


}

void MyThread::run()
{
    qDebug()<<socketDescriptor<< " Starting thread";
    MySocket socket2(this->socketDescriptor);
    //Revisar mas tarde
    /*if(!socket2.setSocketDescriptor(this->socketDescriptor)){
        emit error(socket->error());

    }*/

    /*connect(socket2, SIGNAL(readyRead()), this, SLOT(readyRead()), Qt::DirectConnection);*/


    connect(this, SIGNAL(mensajeRecibido(QByteArray*)), &socket2, SLOT(getMsg(QByteArray*)));
    connect(&socket2, SIGNAL(disconnected()), this, SLOT(disconnected()));
    connect(&socket2, SIGNAL(mensajeEnviarSocket(QByteArray*)), this, SLOT(readyRead(QByteArray*)));
    qDebug() << socketDescriptor<< " Client Connect";



    exec();
}

void MyThread::readyRead(QByteArray*arraySent)
{


    qDebug()<<arraySent->toHex();
    emit mensajeEnviar(arraySent);
}

void MyThread::disconnected()
{
    qDebug() << socketDescriptor<< " Disconnected";

    //socket->deleteLater();

    exit(0);
}

void MyThread::getMsg(QByteArray * array)
{
    emit mensajeRecibido(array);


}

mysocket.cpp (This is the new class)

#include "mysocket.h"

MySocket::MySocket(int socketDescriptor)
{
socket= new QTcpSocket;
socket->setSocketDescriptor(socketDescriptor);
connect(this, SIGNAL(disconnected()), this, SLOT(desconexion()));
connect(this, SIGNAL(readyRead()), this, SLOT(leerMsg()));
qDebug()<<"Hola";
}

void MySocket::leerMsg()
{
    msgSend="";
    // socket->waitForReadyRead(100);
    msgSend=socket->readAll();

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

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

void MySocket::getMsg(QByteArray *array)
{

    arr=*array;
    //qDebug()<<arr;
   // qDebug()<<"server a thread";
    socket->write(arr);
    socket->flush();
    socket->waitForBytesWritten(3000);
}

mysocket.h

#ifndef MYSOCKET_H
#define MYSOCKET_H

#include <QObject>
#include <QTcpSocket>

class MySocket:public QTcpSocket
{
    Q_OBJECT
public:
    MySocket(int socketDescriptor);
signals:
    void mensajeEnviarSocket(QByteArray *arraySend);

public slots:
    void leerMsg();
    void desconexion();
    void getMsg(QByteArray *array);
private:
    QTcpSocket *socket;
    QByteArray arr;
    QByteArray msgSend;
};

#endif // MYSOCKET_H

With this code, I can read the serial port and sending to the client without troubles (I also tried with the telnet command and two connections, and this could with them). But I can read the messages sent. Another trouble that I saw, is that, when I disconect the client, in the server appears the following error: QAbstractSocket::waitForBytesWritten() is not allowed in UnconnectedState

Does anyone knows how I can solve this issues?
Thanks for your help.

Dooham

@Dooham I have solved the trouble with waitforBytesWritten with the function: waitforConnected() that return true if is connected so, I just read if the socket is connected. But I cant read yet.

CP71

@Dooham
Hi,
I quickly watch your code.
I see a thing that is a bit dangerous or I think so, you emit a pointer and not a copy of data without thread synchronization, don’t you?

CP71

@Dooham
And more,
I think you must call addPendingConnection in your incomingConnection

void MyServer::incomingConnection(int socketDescriptor)
{

…

addPendingConnection( thread→GetQTcpSocketPointer() )

thread->start();

}

Dooham

@CP71 I dont know if this is dangerous or not, but it is easy to change, I think. So I will change it later to pass a QByteArray and not a QByteArray pointer. Related to pendingConnection, I don know if this is necessary or not. I am just going to have a few connection. I proved ths code with three clients and I didnt have troubles. With the exception that I cant send message to the serialport, but is a problem that dont depend of the number of connections. However I saw that the trouble is that the socket dont emit the signal readyRead in the socket of the server when I receive a message from a client.

CP71

@Dooham
Ok,
When we have some problems we say, “the computer has always reason”, well almost always.
I’m joking ;)

I already done a TCP Server but I took another road and I hadn't got special problems, so now I haven’t ideas. :(

If I can, I suggest you to solve one problem at a time, I would start at the end, as per QtcpSocket, to try to understand why readyRead seems not working I should check the following checks:

Check with Wireshark or other tools if TCP packets arrive to your device
Check by debug text info about QTcpSocket that you have created (e.g. IP of the client)

Then climb up to TcpServer.

Sorry

Dooham

@CP71 Dont worry, you are helpful. I will tried to find the trouble, I know that must be in my Code of the server, because in the first Code that I published in this thread I could do It. And in a simpler Code for just one connection server-client It also worked.