Add native async support to redis cache backend

[Christopher Bailey]

The latest version of redis-py will support both sync and async clients so sync_to_async will no longer be necessary so it would be nice if the out of the box Redis cache backend supports both natively as well.

​https://github.com/redis/redis-py/releases/tag/v4.2.0rc1

It may be a bit premature since 4.2.0 is still RC, but I wanted to get a ticket out there so it can be on someones radar.

[Mariusz Felisiak]

Tentatively accepted. Do you have an idea for implementation? As far as I'm aware this would require initializing two redis clients: async and non-async.

[Mariusz Felisiak]

Let's wait for the final release first.

[Andrew Chen Wang]

We are currently re-implementing the async client (one last time) in a way that allows for aioredis 1.3.1 performance. ​https://github.com/seandstewart/redis-py-sansio/blob/main/benchmark/conftest.py The RedisLab team will need to approve it first, so I would wait until our new client is either approved/denied ​https://github.com/redis/redis-py/issues/2039. This won't affect the non-async client as the non-async client will still default on the current redis-py interface with the option to also use the new API.

This isn't to say no one should try implementing the async client now; I have high confidence the new client will be merged in with Redis-py as we're gunning for the much-needed performance gain. Just don't be surprised if a few things shift around.

[Christopher Bailey]

Do you have an idea for implementation? As far as I'm aware this would require initializing two redis clients: async and non-async.

I kind of started to implement it, but then realized it was likely going to be a bigger issue then I though. But there is already an abstract RedisClient class that is a wrapper around the base redis.Redis class. It maintains connection polls and handles all of the core commands. It has methods for get, set, add, touch, incr that just calls get_client and makes a new client using the existing connection pull any time it is called.

For Async we can just add something like get_async_client and follow the same pattern within the class. I believe the connection poll should be able to be reused between the sync/async clients, but I am not an expert on Redis.