Create _misc_loop() task thread safely. Fixes #39

[flyte]

Fixes #39

[frederikaalund]

Good catch. :) Simple and straight-forward fix as well. 👍

I think that your explanation in #39 is really good:

It's because the self._client.connect() call is done in an executor (because it blocks on socket creation).

In fact, it's so good that I'd like it to be part of the code. ;) This way, we let future maintainers know why we use a thread-safe variant in this specific case.

Add a reference to the run_in_executor part at line 79:

await loop.run_in_executor(None, self._client.connect, self._hostname, self._port, 60)  # [3]

Then reference this in a comment near your fix at line 303:

def _on_socket_open(self, client, userdata, sock):
    def cb():
        client.loop_read()
    self._loop.add_reader(sock.fileno(), cb)
    def create_task_cb():
        self._misc_task = self._loop.create_task(self._misc_loop())
    # paho-mqtt calls this function from another thread since we use an executor
    # for the `self._client.connect` call (see [3]). Therefore, we use a thread-safe
    # function to start the `_misc_loop` task.
    self._loop.call_soon_threadsafe(create_task_cb)

[flyte]

Comments added. I somehow wrote a bunch of stuff before realising you'd given me comments to use, so they're a little different. Hope it still makes sense.

[frederikaalund]

Thanks. Looks good to me. 👍