Data Appending while sending Data through Qt NamedPipe - c++

Question

Data Appending Problem While sending the data through Namedpipe using QT
localserver.h
#ifndef LOCALSERVER_H
#define LOCALSERVER_H
#include "QLocalSocket"
#include "QLocalServer"
class QLocalSocket;
class LocalServer : public QLocalServer
{
Q_OBJECT
public:
explicit LocalServer(QObject *parent = 0);
void send(QString &msj);
QLocalSocket *mSocket;
private slots:
void receive();
private:
};
#endif // LOCALSERVER_H
localserver.cpp
#include "localserver.h"
#include "QLocalSocket"
#include "QTextStream"
#include "QMessageBox"
LocalServer::LocalServer(QObject *parent) : QLocalServer(parent)
{
mSocket = nullptr;
connect(this,&LocalServer::newConnection,[&](){
mSocket = nextPendingConnection();
});
qDebug()<<"Hello World";
}
void LocalServer::send(QString &msj)
{
qDebug()<<"Sending Data";
if(mSocket)
{
QTextStream T(mSocket);
T<<msj.toStdString().c_str();
mSocket->flush();
}
}
void LocalServer::receive()
{
qDebug()<<"Im here";
QDataStream in(mSocket);
in.setVersion(QDataStream::Qt_5_2);
mSocket->readAll();
qDebug()<<"Data Received";
}
widget.h
#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
#include "QProcess"
#include "QTimer"
#include "QLocalSocket"
#include "localserver.h"
namespace Ui {
class Widget;
}
class Widget : public QWidget
{
Q_OBJECT
public:
explicit Widget(QWidget *parent = 0);
~Widget();
void Connection();
private slots:
void on_start_clicked();
void on_send_clicked();
void on_quit_clicked();
void detect_connection();
void connect_terminate();
void connected();
void send_data();
void receive_data();
QString RandomData();
void on_pbtn_Stop_clicked();
private:
Ui::Widget *ui;
LocalServer *mLocalServer;
QTimer *timer;
QLocalSocket *mSocket;
bool first;
QString data_received;
};
#endif // WIDGET_H
widget.cpp
#include "widget.h"
#include "ui_widget.h"
#include "QProcess"
#include "QDebug"
#include "localserver.h"
#include "QMessageBox"
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
Widget::Widget(QWidget *parent) :
QWidget(parent),
ui(new Ui::Widget)
{
ui->setupUi(this);
Connection();
first = true;
}
void Widget::Connection()
{
mLocalServer = new LocalServer(this);
mLocalServer->listen("Server1");
connect(mLocalServer,SIGNAL(newConnection()),this,SLOT(detect_connection()));
first = true;
timer = new QTimer(this);
timer->setInterval(8);
connect(timer,SIGNAL(timeout()),this,SLOT(send_data()));
}
Widget::~Widget()
{
delete ui;
}
void Widget::on_start_clicked()
{
timer->start();
}
void Widget::on_send_clicked()
{
timer->stop();
}
void Widget::on_quit_clicked()
{
timer->stop();
this->close();
}
void Widget::detect_connection()
{
qDebug()<<"Write Pipe Established";
mSocket = new QLocalSocket(this);
mSocket->connectToServer("Server2");
connect(mSocket,SIGNAL(disconnected()),this,SLOT(connect_terminate()));
connect(mSocket,SIGNAL(connected()),this,SLOT(connected()));
qDebug()<<"Connection Established, Ready to Read";
connect(mSocket,&QLocalSocket::readyRead, [&]() {
QTextStream T(mSocket);
ui->receivedText->addItem(T.readAll());
});
}
void Widget::connect_terminate()
{
qDebug()<<"Read Server Connection Terminated";
QString string = "Stop_Session";
mLocalServer->send(string);
ui->sentText->addItem(string);
}
void Widget::connected()
{
qDebug()<<"Socket Connected to Server";
QString s=" Connection Done ";
mLocalServer->send(s);
}
void Widget::send_data()
{
QString string = RandomData();
mLocalServer->send(string);
ui->sentText->addItem(string);
}
QString Widget::RandomData()
{
srand(time(NULL));
int random_number = rand()%(1920-0 + 1) + 0; // rand() return a number between ​0​ and RAND_MAX
int random_number1 = rand()%(1080-0 + 1) + 0;
int random_number2 = rand()%(10-0 + 1) + 0;
QString s="Contour,"+QString::number(random_number)+","+QString::number(random_number1)+","+QString::number(random_number2);
// Basically this data in "s" gives the actual contours detected data but am using a random generator to test the Local Server and Socket .
return s;
}
void Widget::receive_data()
{
QString string;
QTextStream T(mSocket);
T.readLine();
if(T.readAll()=="Stop")
{
qDebug()<<"Socket About to Close";
QString string = "Stop";
mLocalServer->send(string);
}
else
{
qDebug()<<"Program can continue"<<T.readAll();
}
}
void Widget::on_pbtn_Stop_clicked()
{
timer->stop();
}
At Receiver SIde Program
Receiver.cpp
void Receiver ::Declaration_Of_Server2()
{
// Declaration Of LocalServer i.e Server2
ServerIS = new LocalServer(this);
ServerIS->listen("Server2");
// Connect To a LocalSocket TO The Above LocalServer i.e Server_IS with Server_VS
connect(ServerIS,SIGNAL(newConnection()),this,SLOT(DetectConnection_WithServer1()));
}
void CoFire_MainPage::DetectConnection_WithServer1()
{
// Declaration of LocalSocket i.e Server_VS
SocketIS = new QLocalSocket(this);
SocketIS->connectToServer("Server1");
connect(SocketIS,SIGNAL(readyRead()),this,SLOT(Receiving_VS_Data()));
}
void CoFire_MainPage::Receiving_VS_Data()
{
// Receiving Vs Data From Socket "Socket_IS"
QTextStream msg(SocketIS);
QString str = msg.readLine();
qDebug()<<" VS DATA : "<<str;
}
By this am trying to send data ( example : Contour,1000,800,1 ) from one program to other program
with a speed of 1 data / 8msec but in real scenario it might even go to 1msec data transfer.
but by this at receving end every now and then incomming data is been appended
(example: Contour,1000,800,1Contour,200,400,1Contour,500,650,1 etc... ).
But actually expentected data is
1st
Contour,1000,800,1
next
Contour,200,400,1
next
Contour,500,650,1
etc....
This way the data is getting appeneded before i capture and process the data at receiver .
By this am loosing the precious information .
how do i solve this issue .

Answer 1

readLine() waits for an end-of-line ("\n" or "\r\n"), but in your case you do not send it, you must change to the following:
QString Widget::RandomData(){
srand(time(NULL));
int random_number = rand()%(1920-0 + 1) + 0; // rand() return a number between ​0​ and RAND_MAX
int random_number1 = rand()%(1080-0 + 1) + 0;
int random_number2 = rand()%(10-0 + 1) + 0;
return QString("Contour,%1,%2,%3\n")
.arg(random_number)
.arg(random_number1)
.arg(random_number2);
}
On the other hand it is not necessary to use the reference of the QString, and also it is unnecessary to use toStdString().c_str().
void LocalServer::send(const QString &msj)
{
qDebug()<<"Sending Data";
if(mSocket)
{
QTextStream T(mSocket);
T << msj;
mSocket->flush();
}
}