How to know if client is connected?

[hongquan]

I'm using hbmqtt v0.9.0. My program, as an MQTT client, sometimes gets "Disconnected from broker" log and no longer receive new data from Mosquitto broker. I'm using default config (with auto-reconnect).

I have questions:

• Does "auto-reconnect" work when connection is lost, while waiting for message in deliver_message()?
• Any way to check if client is connected, so that I can call reconnect() and subscribe again?

[hongquan]

Log: https://paste.ee/p/VVAV0

[luchermans]

use MQTTClient(config={"auto_reconnect":True})

[hongquan]

@luchermans Please read my question carefully. I wrote:

I'm using default config (with auto-reconnect).

[luchermans]

Sorry did not look carefully. I have a related issue using python and MQTTClient gives "Disconnected from broker" (simulate by restarting the hbmqtt broker) "auto_reconnect" seems to do reconnect but not re-subscribe.

I have solved the issue by MQTTClient(config={'auto_reconnect':False}) then a Connection lost / Disconnected throws an error so I can handle the re-connect myself.

[hongquan]

@luchermans Thank you. I will try that option. My case also seems to be "not re-subscribed".

[stas-dubrovskyi]

class MockedMQTTClient(MQTTClient):
    @asyncio.coroutine
    def handle_connection_close(self):

        def cancel_tasks():
            self._no_more_connections.set()
            while self.client_tasks:
                task = self.client_tasks.popleft()
                if not task.done():
                    task.set_exception(ClientException("Connection lost"))

        self.logger.debug("Watch broker disconnection")
        # Wait for disconnection from broker (like connection lost)
        yield from self._handler.wait_disconnect()
        self.logger.warning("Disconnected from broker")

        # Block client API
        self._connected_state.clear()

        # stop an clean handler
        #yield from self._handler.stop()
        self._handler.detach()
        self.session.transitions.disconnect()

        if hasattr(self, 'on_connection_close'):
            if inspect.iscoroutinefunction(self.on_connection_close):
                yield from self.on_connection_close()
            else:
                self.on_connection_close()

        if self.config.get('auto_reconnect', False):
            # Try reconnection
            self.logger.debug("Auto-reconnecting")
            try:
                yield from self.reconnect()
            except ConnectException:
                # Cancel client pending tasks
                cancel_tasks()
        else:
            # Cancel client pending tasks
            cancel_tasks()

    def set_close_callback(self, callback):
        self.on_connection_close = callback

Have done for myself in this dirty way.

If some kind of callback`s applicable for current project. I'm glad to prepare PR

[sronsiek]

@stas-dubrovskyi: Nice - but hbmqtt should really supply a means of setting on_connect / on_message callbacks, as paho does. It's not difficult - shame the pkg is neglected as there is call for it ...

[Equidamoid]

Yeah, looks like the only way is to not use the broken reconnect functionality:

    async def process_messages(self):
        while True:
            try:
                await self._cli.reconnect()
                await self._cli.subscribe([...])
                while True:
                    msg: hbmqtt.session.ApplicationMessage = await self._cli.deliver_message()
                    if not msg:
                        logger.warning("No message. Disconnected?")
                        raise RuntimeError('Disconnected?')
                    do_stuff(msg)
            except KeyboardInterrupt:
                raise
            except:
                logger.exception("whoops")
                await asyncio.sleep(5)

dirty but works