reconnect logic may get in endless loop

[kriskep]

It is possible that the reconnection procedure may get in an endless loop of close and connect events.

The code below reproduces the problem on Ubuntu 12.04 with default mosquitto installation. Note I had to use iptables to simulate bad network conditions.

var mqtt = require('mqtt');

var host = '127.0.0.1';
var port = 1883;
var args = {
     keepalive: 10,
     reconnectPeriod: 6000
};

var LOG = function(m) {
    console.log(new Date().toLocaleString() + ': ' + m);
}

var mqttclient = mqtt.createClient(port, host, args);

mqttclient.on('connect', function() {
    LOG('mqtt client connected');
});

mqttclient.on('disconnect', function() {
    console.log('mqtt client disconnected');
});

mqttclient.on('error', function(err) {
    LOG('mqtt client error:');
        LOG(err);
});

mqttclient.on('close', function(err) {
    LOG('mqtt client closed');
});

setTimeout(function() {
    var exec = require('child_process').exec;
    exec('sudo iptables -A INPUT -p tcp --dport 1883 -j DROP', function(error) {
        if (error !== null) {
            LOG('error configuring iptables '+error);
        } else {
            LOG('iptables drop 1883');
            setTimeout(function() {
                exec('sudo iptables -D INPUT -p tcp --dport 1883 -j DROP', function(err) {
                    if (error !== null) {
                        LOG('error configuring iptables '+error);
                    } else {
                        LOG('iptables accept 1883');
                    }
                } );
            }, 15000 );
        }
    } );
}, 10000 );


setInterval(function() {
    mqttclient.publish('/test/ping', 'testmsg');
}, 1000 );

[kriskep]

I digged a bit further and the problem is the following:

1. ping response fails and a close event is generated. Socket.end() is called. reconnect timer is started. (reconnectPeriod)
2. after reconnectPeriod, reconnection attempt is made
3. a close event is generated for the socket.end() in 1. reconnectTimer is started again
4. network connection is restored
5. reconnection succeeds and connect is sent
6. reconnectTimer from step 3 expires, and a new reconnection attempt is made(!)
7. mosquitto detects 2 connections for the same clientId and closes one of them
   etc ....

[kriskep]

kriskep@2e662a8 fixes this problem

[mikelfo]

Thank you, I was also experiencing this issue!