Feedback requested: Python SDK config and status object for debugging

[BertKleewein]

Looking for feedback on mqtt_transport.py changes. Tony and I have been talking about something like this as a way for customers to get a quick status on the health of our library. This is far from complete, but the intention is to provide data for observability/debugging only with the hope of avoiding the need to pour through reams of debug data.

The config object looks like this;

  "paho_config": {
    "transport": "websockets",
    "protocol": "4",
    "keepalive": 60,
    "connect_timeout": 5.0,
    "reconnect_on_failure": true,
    "reconnect_delay_min": 7200,
    "reconnect_delay_max": 120,
    "host": "bertk.azure-devices.net",
    "port": 443,
    "proxy_args": {},
    "socket_class": "WebsocketWrapper",
    "socket_name": "No socket name"
  },

and the status object looks like this:

  "paho_status": {
    "connect_rc_codes": {
      "0": 2
    },
    "on_connect_rc_codes": {
      "0": 2
    },
    "connect_exceptions": {
      "timeout": 3
    },
    "disconnect_rc_codes": {},
    "on_disconnect_rc_codes": {
      "16": 1,
      "0": 1
    },
    "disconnect_exceptions": {},
    "publish_rc_codes": {
      "0": 631
    },
    "publish_exceptions": {},
    "subscribe_rc_codes": {},
    "subscribe_exceptions": {},
    "unsubscribe_rc_codes": {},
    "unsubscribe_exceptions": {},
    "count_message_received": 0,
    "count_subscribe": 0,
    "count_suback": 0,
    "count_unsubscribe": 0,
    "count_unsuback": 0,
    "count_publish": 631,
    "count_puback": 631,
    "shut_down": false,
    "time_since_last_paho_traffic_in": "0:00:00.779999",
    "time_since_last_paho_traffic_out": "0:00:05.885535",
    "client_object_id": 140285330079296,
    "thread_name": "Thread-14",
    "thread_is_alive": "True",
    "len_out_mesage_queue": 0,
    "len_in_message_queue": 0,
    "len_out_pakcet_queue": 0,
    "thread_terminate": false,
    "paho_connection_state": 1
  },

[anthonyvercolano]

Spelling?

[anthonyvercolano]

Well I like it.

[cartertinney]

Comments

[cartertinney]

Since this requires Python 3.7, there should be an update to the setup.py to exclude Python 3.6 (and a removal of the associated classifier)

[cartertinney]

This is.... super nitpicky... (but also kind of not) but you aren't supposed to use """ to make comments anywhere except a docstring. As I recall, they are interpreted differently by the runtime, because the """ is a string literal, wheras a # comment just gets completely ignored.

[BertKleewein]

No, not nitpicky. These string literals end up taking space at runtime, so the distinction is important. I did it this way on purpose. Even though docstrings on attributes are technically not part of the Python standard, some tools will pick these up (if you put them after the attribute definition). I think PyCharm will pick these up, and maybe some versions of Sphynx.

[cartertinney]

I feel as though accessing convention-private attributes of Paho is dangerous. There is no guarantee they don't change in an update to Paho, which could break anyone using our library until we make an update. Furthermore, that risk doesn't really seem worth it for a logging utility.

I could be convinced of the utility if we were to build some exception handling in to protect against this possibility, but even still, seems dicey.

[BertKleewein]

I agree that it's dangerous. I also think it's super useful -- at least some of these are. Using getattr() with a default would be much safer.

[cartertinney]

Great change. Was thinking of doing this myself.