QT app:exec is blocking the code.

Ayush Gupta

@JonB I am pasting my code here

UdpSocket.h

#ifndef UDPSOCKET_H
#define UDPSOCKET_H
#include <QUdpSocket>
#include <MMISimForm.h>

class UdpSocket : public QObject
{

    Q_OBJECT
public:
       UdpSocket(QObject* parent, int portno, MMISimForm* simForm_);
       ~UdpSocket();

private:
       int portNo_;
       MMISimForm* mmiSimForm_;
       QUdpSocket *socketUdp;

public slots:
       void dataRead();

//methods
public:
       int sendData();

};

#endif // UDPSOCKET_H

UdpSocket.cpp

#include "UdpSocket.h"


UdpSocket::UdpSocket(QObject *parent, int portno, MMISimForm* simForm_)
          :QObject(parent), portNo_(portno), mmiSimForm_(simForm_)
{

    socketUdp = new QUdpSocket(this);
    socketUdp->bind(QHostAddress::LocalHost, portNo_);
    connect(socketUdp, SIGNAL(readyRead()), this, SLOT(dataRead()));
}


UdpSocket::~UdpSocket()
{

}

void UdpSocket::dataRead()
{
    QByteArray buffer;
    QHostAddress sender;
    quint16 senderPort;
    buffer.resize(socketUdp->pendingDatagramSize());
    int test = socketUdp->readDatagram(buffer.data(), buffer.size(),
                                        &sender, &senderPort);
    QString text;
    text.sprintf("Bytes Read %d", test);
    mmiSimForm_->logMessage(buffer);
}

int UdpSocket::sendData()
{
     return socketUdp->writeDatagram("GetStream", QHostAddress::LocalHost,
                               5000);
}

My non - qt application code

ServerSocket.cpp

#include "ServerSocket.h"
#include "mmisimlogger.h"
ServerSocket::ServerSocket()
{
    WSAStartup(0x0101, &w) != 0;
    /* Open a datagram socket */
    sd = socket(AF_INET, SOCK_DGRAM, 0);

    /* Clear out server struct */
    memset((void *)&server, '\0', sizeof(struct sockaddr_in));
    memset((void *)&client, '\0', sizeof(struct sockaddr_in));
    server.sin_family = AF_INET;
    server.sin_port = htons(5000);

    /* Get host name of this computer */
    gethostname(host_name, sizeof(host_name));
    hp = gethostbyname(host_name);

     /*Assign the address
    server.sin_addr.S_un.S_un_b.s_b1 = hp->h_addr_list[0][0];
    server.sin_addr.S_un.S_un_b.s_b2 = hp->h_addr_list[0][1];
    server.sin_addr.S_un.S_un_b.s_b3 = hp->h_addr_list[0][2];
    server.sin_addr.S_un.S_un_b.s_b4 = hp->h_addr_list[0][3];*/
    server.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");

    bind(sd, (struct sockaddr *)&server, sizeof(struct sockaddr_in));

}

int ServerSocket::recieveData()
{

    client_length = (int)sizeof(struct sockaddr_in);
    int test = 0;



    //Receive bytes from client
    bytes_received = recvfrom(sd, buffer, 4096, 0, (struct sockaddr *)&client, &client_length);




     bytes_received = sendto(sd, (const char *)"hello", strlen("hello"),
                            0, (const struct sockaddr *) &client,
                               client_length);




    char teststring[40];
    sprintf(teststring,"ErrorCode %d", bytes_received);
    MMISimLogger::instance()->log(teststring);
    MMISimLogger::instance()->close();


    if (bytes_received < 0)
    {

    }
    else
    {
        test = bytes_received;
        //MMISimLogger::instance()->log(buffer);
        //MMISimLogger::instance()->close();
        return test;
    }
}

I know this code is mess but I don't know where I am doing wrong.

[Fixed code tags ~kshegunov]

Ayush Gupta

It seems that readyRead signal will be not be emitted when we send data from other non-QT application.

I am able to connect to the server (QT application side) when I send data using send() in non-QT application it returns number of byte send correctly but no readyRead signal is emitted.

J.Hilk

@Ayush-Gupta said in QT app:exec is blocking the code.:

It seems that readyRead signal will be not be emitted when we send data from other non-QT application.

No, there is no differentiation between Qt and non Qt UDP-Source. I'm able to receive and send UDP datagrams just fine that way.

I am able to connect to the server (QT application side) when I send data using send() in non-QT application it returns number of byte send correctly but no readyRead signal is emitted.

Pls make sure you actually really send data. A 3rd Party listening software could help here.

JonB

@Ayush-Gupta said in QT app:exec is blocking the code.:

It seems that readyRead signal will be not be emitted when we send data from other non-QT application.

As said multiple times, there is no difference in socket operation between a Qt program versus a non-Qt one, nor between blocking or non-blocking. TCP is TCP, UDP is UDP, regardless of who the sender/receiver is.

Concentrate instead on discovering what you are doing differently/wrong in either side of the communication.

Ayush Gupta

@J-Hilk Is it possible for you to share the example code?

Ayush Gupta

void MyTcpServer::incomingConnection(qintptr socketDescriptor)
{
    socket = new QTcpSocket();

    ```
// set the ID
    if(!socket->setSocketDescriptor(socketDescriptor))
    {
        //OnErrorSocket(socket->error());
        return;
    }
    else
    {
        simForm_->logMessage("Server Started");
        socket->setSocketOption(QAbstractSocket::KeepAliveOption, 1);
        //OnConnected();
    }

    // connect socket and signal
    // note - Qt::DirectConnection is used because it's multithreaded
    //        This makes the slot to be invoked immediately, when the signal is emitted.
    connect(socket, SIGNAL(readyRead()), this, SLOT(OnReadyRead()), Qt::DirectConnection);
    connect(socket, SIGNAL(disconnected()), this, SLOT(OnDisconnected()));
}


incomingConnection call is success means  connection is successful.
But when sending data using below function. ready Read is not emitting.

int ServerSocket::sendData()
{
   send(sd , "hello" , strlen("hello") , 0 );
}

ClientSocket::ClientSocket()
{
    WSAStartup(0x0101, &w) != 0;
    /* Open a datagram socket */
    sd = socket(AF_INET, SOCK_STREAM, 0);

    /* Clear out server struct */
    memset((void *)&server, '\0', sizeof(struct sockaddr_in));

    server.sin_family = AF_INET;
    server.sin_port = htons(5000);
    server.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");

    connect(sd, (struct sockaddr *)&server, sizeof(server));
}

Ayush Gupta

@J-Hilk @JonB Is I am doing anything wrong in code?

J.Hilk

@Ayush-Gupta said in QT app:exec is blocking the code.:

@J-Hilk Is it possible for you to share the example code?

maybe I would have to cut out as significant part, to be able to show it

2nd post

Here you're using a TcpSocket, previously you posted Udp. What is it, do you use both at the same time?

@J-Hilk @JonB Is I am doing anything wrong in code?

are you sure you pass the correct port when creating the class. I noticed, your write function has hardcoded port value while your bind uses a value defined at run time

Ayush Gupta

@J-Hilk Yes I am using same port number. I failed using UDP then I am trying using UDP.

Port number is used correctly that is why connection was established and incomingConnection() was called.

Ayush Gupta

@J-Hilk Is it possible for you to post some working code?