Replay queue for new subscribers

[TheoBabilon]

Hi @smithk86,

Thanks for your work on asyncio-multisubscriber-queue!

I think it might be great (but subject to discussion, as this might be out-of-scope for this library) to have some sort of "non-fire-and-forget" functionality where new subscribers would replay the whole history of updates pushed to the multisubscriber-queue; currently it is plain "fire-and-forget" (and this might be by design!) so users need to ensure that subscribers are already subscribed to the queue before producer start producing messages, otherwise messages might just get lost (https://github.com/smithk86/asyncio-multisubscriber-queue/blob/main/asyncio_multisubscriber_queue/queue.py#L105).
This "forces" users to have some flow-control (as this scenario can easily happen in an async-world) between producer and potential consumers, which can be sometimes inconvenient.

Curious on what you think on the above? If this is something you believe might make sense I'm happy to try and tackle this when I get some time.

[smithk86]

Hello, @TheoBabilon.

I'm so glad you are finding the module useful!

The one thing I would like to avoid is unnecessary complexity. Maybe we could look at making it more extensible so upstream projects could more easily implement extra functionality?

1. Allow a subclass of MultisubscriberQueue to override the Queue class. This could allow the user to make a subclass of asyncio.Queue which could implement extra logic in the Queue's methods.
2. Add hooks that could be registered and executed when certain functions of MultisubscriberQueue are called. The four likely candidates seem to be add(), remove(), put(), and close().

I already took a stab at #1. Take a look at this commit. There is a test as part of the commit to show how to use it.

Let me know what you think!
Kyle