How to correctly re-subscribe to topic after connection lost

[MarioRossi37]

I have to find a way to re-subscribe to topics after connection lost. Currently I have something like this:

// [Other Code...]
opts := mqtt.NewClientOptions()
opts.AddBroker(fmt.Sprintf("%s:%d", brokerAddress, brokerPort))
opts.SetClientID(clientID)
opts.SetTLSConfig(tlsConfig)

opts.AutoReconnect = true
opts.OnConnect = connectHandler
opts.OnConnectionLost = connectLostHandler
opts.CleanSession = true

client = mqtt.NewClient(opts)

if token := client.Connect(); token.Wait() && token.Error() != nil {
    return nil, token.Error()
} else {
    return &MqttClient{client}, nil
}
// [Other Code...]

and then on the onConnect handler something similar to

if token := c.Subscribe(topic1, 1, messageHandler1); token.Wait() && token.Error() != nil {
    log.Fatal(token.Error())
        return
}
if token := c.Subscribe(topic2, 1, messageHandler2); token.Wait() && token.Error() != nil {
    log.Fatal(token.Error())
    return
}

That way if the device loses connection and then resumes it, entering the onConnect should re-subscribe to the topics.

However, what happens if the subscription fails? I would like to automatically retry to subscribe (and not just log the error). What is the correct way to achieve this?

[MattBrittan]

Please ask this kind of question in one of the resources shown in the readme. You need to consider what could lead to a failure and whether you want to retry (if the broker returns an error then it's likely you will get the same error on repeat attempts). The most likely cause of failure is probably a network issue, but if that happens the client will reconnect, so your current code will retry...

[MattBrittan]

Closing this as it's something best discussed elsewhere (and not really an issue specific to this particular client).