Receive Data From UdpSocket In Thread

Marco Flad

when using Readyread() Signal In MAINWINDOW working good my problem when i move it to thread didnt emit data
CODE:

udpreceiver.h

#ifndef UDPRECEIVER_H
#define UDPRECEIVER_H

#include <QObject>
#include <QDebug>
#include <QThread>
#include <QUdpSocket>
class UdpReceiver : public QObject
{
    Q_OBJECT
public:
    explicit UdpReceiver(QObject *parent = nullptr);
    ~UdpReceiver();

signals:
    void SendDataToGui(QByteArray frame);
    //to Send Feed Back To THE USER InERFACE
public slots:
 void readPendingDiagrams();

private:
    QUdpSocket *socket;
};
#endif // UDPRECEIVER_H

udpreceiver.cpp

#include "udpreceiver.h"
#include <QThread>
#include <QDebug>

UdpReceiver::UdpReceiver(QObject *parent) : QObject(parent)
{
    //constractor
    qDebug() << "UDP Construction thread:" << QThread::currentThread();
 
   //intialize
    socket = new QUdpSocket(this);     
    socket->bind(36000, QUdpSocket::ShareAddress);   
    socket->connect(socket, SIGNAL(readyRead()), this, SLOT(readPendingDiagrams()));  
}

UdpReceiver::~UdpReceiver()
{
     qDebug() << "UDP DE-Construction thread:" << QThread::currentThread();
}

void UdpReceiver::readPendingDiagrams()
{

     qDebug() << "UDP READ thread:" << QThread::currentThread();
   
  QByteArray Data;
    while (socket->hasPendingDatagrams()){
     Data.resize(socket->pendingDatagramSize());
     QHostAddress sender;
     quint16 senderPort;

     socket->readDatagram(Data.data(), Data.size(),&sender, &senderPort);
     qDebug() << "Message from: " << sender.toString();
     qDebug() << "Message port: " << senderPort;
     qDebug() << "Message: " << Data;
     qDebug() << sizeof (Data);

}
    emit SendDataToGui(Data);
}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QThread>
#include <QUdpSocket>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_connect_clicked();

    void on_subscrip_clicked();

    void on_info_clicked();

    void ReciveDataFromThread(QByteArray array);

private:
    Ui::MainWindow *ui;
    QThread *UDPThread;
    QUdpSocket *Sendsocket ;
};
#endif // MAINWINDOW_H

mainwindow.cpp


#include "mainwindow.h"
#include "ui_mainwindow.h"

#include "udpreceiver.h"
#include <QThread>
#include <QDebug>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    qDebug() << "GUI thread:" << QThread::currentThread();
    ui->setupUi(this);
 
    //SEND Socket
    Sendsocket = new QUdpSocket(this);     //output data Socket Work as server
    Sendsocket->bind(36000);   //to send on 36000


   //Start Recive Socket
    UDPThread = new QThread(this);
    UdpReceiver *udpreciver = new UdpReceiver;  //now this live in Mainwindow
    udpreciver->moveToThread(UDPThread);  //now leaved in another thread
    connect(UDPThread,&QThread::started,udpreciver,&UdpReceiver::readPendingDiagrams);
    UDPThread->start();

}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_connect_clicked()
{
    QByteArray Data;
    Data.append("10 04 00 00 04 10 03");
    QByteArray n = Data.fromHex(Data);
    qDebug()<<"n:"<<n ;
    Sendsocket->writeDatagram(n, QHostAddress("192.168.50.55"),36000); //[0] Define The Lisner IP AND PORT

}

void MainWindow::on_subscrip_clicked()
{

}

void MainWindow::on_info_clicked()
{
}

void MainWindow::ReciveDataFromThread(QByteArray array)
{
}

Thanks,

mrjj

Hi
For me - your bind returned false and gave this error
QNativeSocketEngine::hasPendingDatagrams() was called in QAbstractSocket::UnconnectedState

I then changed

UdpReceiver::UdpReceiver(QObject *parent) : QObject(parent)
{
//constractor
qDebug() << "UDP Construction thread:" << QThread::currentThread();

//intialize
socket = new QUdpSocket(this);
qDebug() << "bind:" << socket->bind(QHostAddress::LocalHost,36000, QUdpSocket::ShareAddresst); // localhost addded
qDebug() << "conn:" << socket->connect(socket, SIGNAL(readyRead()), this,
                                       SLOT(readPendingDiagrams()));

}

and in mainWinow

Sendsocket->writeDatagram(n, QHostAddress::LocalHost,
36000); //[0] Define The Lisner IP AND PORT

and then it works

GUI thread: QThread(0x199eb0)
UDP Construction thread: QThread(0x199eb0)
bind: true
conn: true
UDP READ thread: QThread(0x7ae870)
UDP READ thread: QThread(0x7ae870)
Message from:  "127.0.0.1"
Message port:  36000
Message:  "\x10\x04\x00\x00\x04\x10\x03"

even with udpreciver->moveToThread(UDPThread);

Marco Flad

this is the output :

GUI thread: QThread(0x1e9220)
UDP Construction thread: QThread(0x1e9220)
bind: false
conn: true
UDP READ thread: QThread(0x891a00)

here i am send and recive data from another pc on the network after modifying this line the send socket didn't work.

Sendsocket->writeDatagram(n, QHostAddress::LocalHost,36000); //[0] Define The Lisner IP AND PORT

thanks,

mrjj

@Marco-Flad said in Recive Data From UDpSocket In Thread:

bind: false

Your bind fails again. it seems. you have to find out why.

Also if you test on 2 pc, Im not sure QHostAddress:: LocalHost can be correct for both.

Did you try with your original
Sendsocket->writeDatagram(n, QHostAddress("192.168.50.55"),36000);

I assume the 192.168.50.55 is the IP of the other pc ?

Marco Flad

@mrjj said in Recive Data From UDpSocket In Thread:

of

yes i tried it and worked in send and receive in mainwindow.cpp but not in thread
yes this ip of 2nd pc

mrjj

@Marco-Flad

So on other pc, you run the same program and it reports
false for bind ?

It works for me with thread - on the same machine running the app 2 times.
and sending from one to the other.

I cannot test between 2 pc currently.

Marco Flad

@mrjj
i used this to get the error

    if(!socket->bind(36000, QUdpSocket::ShareAddress)){
       qInfo() << socket->errorString();
    }

the Debugger output is :

"The bound address is already in use"

this mean this address used by the Send Socket

i change the send socket to be :

Sendsocket->bind(QHostAddress("169.168.50.55"),36000);

the Debugger output is :

GUI thread: QThread(0x1849220)
UDP Construction thread: QThread(0x1849220)
bind: true
conn: true
QNativeSocketEngine::bind() was not called in QAbstractSocket::UnconnectedState
"Unknown error"

mrjj

@Marco-Flad
Hi did you find out why
"The bound address is already in use" ?