Async PubSub listeners?

[mikeyk]

Hi @alisaifee!

Currently we use one PubSub object per user connection, and then use listen() to handle incoming responses on just that one subscribed channel. We'd like to move to having one PubSub per uvicorn worker instead. To do that, however, we need to have the registered handlers be async, since they need to do work like write back to the client websockets.

A proposal would be:

1. Make handle_message an async function
2. When grabbing handlers from the self.patterns or self.handlers map, check if they are coroutines or sync functions; if sync, just call regularly, otherwise await them. (can be something like Starlette's is_async_callable )

What do you think? Only downside would be a slightly more expensive call to handle_message since making it async has a small amount of overhead. Happy to take this on if it sounds good to you.

[alisaifee]

On first glance this seems perfectly reasonable - and yes please go ahead and put up a PR!

[mikeyk]

Great, thanks; here's the PR: #125

[alisaifee]

Available now in 4.10.0