redis-py async pipelines not being awaited is an error

[bentheiii]

types-redis incorrectly marks async Pipeline commands as coroutines, when in truth they do not need to be awaited to work (and are not implemented as coroutines.

the following snippet

from redis.asyncio import Redis
async def foo(redis: Redis):
  pipeline = redis.pipeline()
  pipeline.get(...)
  pipeline.set(...)
  await pipeline.execute()

is functional according to redis-py, but fails mypy with the error error: Value of type "Coroutine[Any, Any, bool]" must be used

[srittau]

This is basically the same issue we have with the non-async Pipeline class: It needs to override all redis command methods so that it doesn't inherit them from the base (async) Redis class. Any PRs to improve the situation are welcome.

[bentheiii]

Hi @srittau, I'd be happy to submit a PR, but I think a solution must be agreed upon beforehand. AFAICT every command in Pipeline can return either the pipeline itself or a coroutine to the command result. This leaves with 3 options I can see:

1. All commands return Pipeline | Coroutine[Any, Any, ActualResultType] this is technically correct, but it means that neither pipeline.get(...).set(...).execute() nor (await pipeline.get(...)).decode() will succeed.
2. All commands return Any. This will solve our issues but obviously will not catch other errors.
3. wait for AnyOf I guess.

[srittau]

Just to clarify (I didn't check): asyncio.Pipeline can return either a coroutine or itself? How is it decided what is returned? In case we can't model this, we should indeed just return Any, unfortunate as that is.

[bentheiii]

AFAICT (judging by the source code), asyncio.Pipeline will return itself for method pipelining, UNLESS it exists in a special mode called watching, which it can enter at any time by someone calling the watch method, or exited by calling the multi method.

pipeline = redis.pipeline()
pipeline.get(...) # will return pipeline
pipeline.set(...)  # will return pipeline

pipeline.watch(...)  # will return a coroutine
pipeline.get(...) # will return a coroutine
pipeline.set(...)  # will return a coroutine

pipeline.multi() # returns none
pipeline.get(...) # will return pipeline
pipeline.set(...)  # will return pipeline

I'll get started on an Any solution

[bentheiii]

#8325