redis-BackEnd listener just listen once

[Fly-Playgroud]

https://github.com/encode/broadcaster/blob/22e8b2afb131321dcd0a9a06be2d860849cfbe5a/broadcaster/_backends/redis.py#L43-L53

the redis-backend pub-listener only just listen once, if channels unsubscribed until here no channels to subscribe, this async.Task will exited. Even if new subscriptions come in later, no messages can be listened because of it has eixted.

[Fly-Playgroud]

I think maybe use while loop to keep running

[Fly-Playgroud]

solve code:

 async def _pubsub_listener(self) -> None: 
     # redis-py does not listen to the pubsub connection if there are no channels subscribed 
     # so we need to wait until the first channel is subscribed to start listening
     while True:
         await self._ready.wait() 
         async for message in self._pubsub.listen(): 
             if message["type"] == "message": 
                 event = Event( 
                     channel=message["channel"].decode(), 
                     message=message["data"].decode(), 
                 ) 
                 await self._queue.put(event) 
        self._ready.clear()

[alex-oleshkevich]

This looks like a great solution! Can you make a PR?

[Fly-Playgroud]

This looks like a great solution! Can you make a PR?

ok， I will do it

[alex-oleshkevich]

merged,