Fix MQTT reconnection bug

RosLD commented 1 year ago

Problems found

The first problem I found is that if the iotagent is provisioned with a group, and thus, subscribed to a topic if the broker disconnects in my case does not resubscribe to those topics, hence all the reports made from the devices will be ignored.

The second problem is about a bug in the code. As I could understand, in case of a disconnection it is supposed to wait a larger time every time it tries to reconnect and fail, it will try 5 times, but there is a problem with the function sleep, because it is not executed asynchronously and thus the reconnection times are not incremental, there will be 1 second between each trial because it is the default time in the mqtt library. I could not fix the async problem either, I think it is related to the mqtt library and how its event handler works.

Proposed changes

To fix both problems described I used the option reconnectPeriod when the mqtt client is being created, this way if the mqtt broker dissapears it will try to reconnect every 10 minutes. It will also resubscribe to the topics.
I have removed the lines inside the event handler that stops the client from trying to reconnect if it fails 5 times. I find this more logical since if it is the broker which failed you wont need to restart both services, but if there was a reason for stopping it just let me know and I can change it back.
I have also removed lines that, as a result of this changes were left unused such as, the sleep function and some variables.

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[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

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RosLD commented 1 year ago

I have read the CLA Document and I hereby sign the CLA

Atos-Research-and-Innovation / IoTagent-LoRaWAN