qmqtt auto reconnect on disconnet

RahibeMeryem · 22 Oct 2018, 04:37

Hi

I am connecting to the qmqtt

m_client = new QMqttClient(this);


    m_client->setHostname("localhost");
    m_client->setPort(1883);
    m_client->setClientId("RASPBERRY-009");

    m_client->setUsername("pullu");
    m_client->setPassword("pullu");
    m_client->setKeepAlive(30);

    m_client->setCleanSession(false);

    m_client->connectToHost();
    QObject::connect(m_client, &QMqttClient::stateChanged, this, &Publisher::updateStateChange);
    QObject::connect(m_client, &QMqttClient::connected, this, &Publisher::sendMessages);

When its connected looking a folder new files than sending to the emqt broker.

There sometimes network problem or broker restart etc. Than client lost his connection and state change 1.

than :

void Publisher::updateStateChange()
{
    const QString content = QDateTime::currentDateTime().toString()
                    + QLatin1String(": State Changed : ")
                    + QString::number(m_client->state());

    qDebug() << " -- *** **  state change .. : " << content << endl;
    while (m_client->state()  != 2 ){
        qDebug() << " Retrying.... . . . " << endl;
        m_client->setHostname("localhost");
        m_client->setPort(1883);
        m_client->setClientId("RASPBERRY-009");

        m_client->setUsername("pullu");
        m_client->setPassword("pullu");
        m_client->setKeepAlive(30);


        m_client->setCleanSession(false);

        m_client->connectToHost();
        const QString content = QDateTime::currentDateTime().toString()
                        + QLatin1String(": State Changed : ")
                        + QString::number(m_client->state());
        qDebug() << " -- *** **  state === .. : " << content << endl;


        QThread::sleep(2);
}

I am checking state than try to recover my connection .

I couldt succed.

How can I keep my client always connected if bad things happen try to reconnect untill connected :)

Best

jsulm · wrote on 22 Oct 2018, 04:37

@RahibeMeryem said in qmqtt auto reconnect on disconnet:

while (m_client->state() != 2 ){

NEVER use such loops and QThread::sleep(2); in event driven applications!
You're blocking Qt event loop!

Use a QTimer for reconnect.

RahibeMeryem · 24 Oct 2018, 05:27

I figured it out before read this :)

Another question for same topic:

can I connect signals from threads signal from it ? like :

Messenqt::Messenqt(QObject *parent) : QObject(parent)
{


         m_client = new QMqttClient(this);


    m_client->setHostname("localhost");
    m_client->setPort(1883);
    m_client->setClientId("ERRY-009");

    m_client->setUsername("xxxxx");
    m_client->setPassword("xxxxx");
    m_client->setKeepAlive(300);
    m_client->setCleanSession(false);

    m_client->connectToHost();
    //yeni slot mekanizmasi. kendi icinde &Publisher örneği..
    QObject::connect(m_client, &QMqttClient::stateChanged, this, &Messenqt::updateStateChange);


    QObject::connect(m_client, &QMqttClient::connected, this, &Messenqt::subscribe_results);
    QObject::connect(m_client , &QMqttClient::messageReceived , this , &Messenqt::result_received);

//    connect(messqt->m_client, &QMqttClient::stateChanged, messqt, &Messenqt::updateLogStateChange);
//    connect(m_client, &QMqttClient::disconnected, this, &Publisher::disconnect);
//    connect(messqt->m_client, &QMqttClient::connected, messqt, &Messenqt::sendingMessage);

    msg_timer = new QTimer(this);
    connection_check = new QTimer(this);

            //    m_client->subscribe(result_topic ,2);


    //TODO big chip save timer.
    connect(msg_timer, SIGNAL(timeout()) , this , SLOT(sendMessages()));
    msg_timer->start(4000);

    connect(connection_check , SIGNAL(timeout()) , this , SLOT(reconnect()));
    connection_check->start(5000);


         }

This thread started from the main GUI thread.

When started the app it says :

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

jsulm · wrote on 24 Oct 2018, 05:27

@RahibeMeryem said in qmqtt auto reconnect on disconnet:

can I connect signals from threads signal from it ?

What do you mean? Do you mean to connect a signal to a slot living in different threads? If so then yes you can (use Qt::QueuedConnection connection type). But that doesn't mean that what you're doing in other thread with your socket is allowed.

RahibeMeryem · 24 Oct 2018, 07:47

for example :

Main thread is Widget.cpp which is updating UI.

Messenqt.cpp is also a thread created by Widget.cpp with moveThread .

so how can I use

connect(m_client, &QMqttClient::connected, this, &Messenqt::subscribe_results);

in Messenqt ?

jsulm · wrote on 24 Oct 2018, 07:47

@RahibeMeryem You should do the connect in Widget.cpp and add Qt::QueuedConnection to the connect call

RahibeMeryem · 24 Oct 2018, 10:40

Whey there is not an autoconnect on diconnect is Qt qmqtt :) . There is in the pyhthon... is there any ?

jsulm · wrote on 24 Oct 2018, 10:40

@RahibeMeryem You should ask qmqtt project I guess

RahibeMeryem · 24 Oct 2018, 12:33

Looking into it, but I am confused qmqtt in thread and connecting signal slot inside that thread also to check connection and re-connect.

is there any minimalistic example for qmqtt running in a thread like:
mainwindow.cpp

    messenqt_thread = new QThread();
    messqt = new Messenqt();
    messqt->moveToThread(messenqt_thread);
    messenqt_thread->start();

Messenqt.cpp

Messenqt::Messenqt(QObject *parent) : QObject(parent)
{


//        qRegisterMetaType<QMqttClient::ClientState>("QMqttClient::ClientState");
        
        m_client = new QMqttClient(this);
        m_client->setHostname("xx.15.43.84");
        m_client->setPort(1883);
        m_client->setClientId("001");



        qDebug() << "?? is here"  << m_client->state() << endl;
        if (m_client->state() == QMqttClient::Disconnected){
            qDebug() << "state Disconnected 01" << endl;}
        else{qDebug() << "state Connected 01" << endl;};


            connect(m_client, &QMqttClient::stateChanged, this, &Messenqt::updateLogStateChange);
            connect(m_client, &QMqttClient::disconnected, this, &Messenqt::brokerDisconnected);
            connect(m_client, &QMqttClient::connected, this, &Messenqt::succesfully_connected);
            connect(m_client, &QMqttClient::pingResponseReceived, this , &Messenqt::pingReceived);

}

void Messenqt::brokerDisconnected()
{
    qDebug() << "Qmqt -- :: Disconnected ????****????*****???? " << endl;

    if (m_client->state() != 2){
        qDebug() << " Re-connecting......" << endl ;
        qDebug ()<< " state :  " << m_client->state() << endl;
        m_client->setHostname("xx.15.43.84");
        m_client->setPort(1883);
        m_client->setClientId("RASPBERRY-009");

        m_client->setUsername("xx");
        m_client->setPassword("xx");
        m_client->setKeepAlive(60);
        m_client->setCleanSession(false);

        m_client->connectToHost();


}

this is not working... I see debug message at the emqt server :

14:49:37.455 [debug] Client(78.187.191.133:50395): Terminated for {shutdown,closed}

jsulm · wrote on 24 Oct 2018, 12:33

@RahibeMeryem said in qmqtt auto reconnect on disconnet:

I am confused qmqtt in thread and connecting signal slot inside that thread also to check connection and re-connect

As I said you can connect signals slots across threads