Expose compression level on CompressionLayer

[Zerowalker]

Feature Request

Motivation

Being able to set the compression level will allow one to tweak the settings for optimal speed/compression.
It can be quite a big difference in speed mostly, especially if things are at max.

Proposal

My thoughts are that with_quality is exposed from async_compression.
https://docs.rs/async-compression/latest/src/async_compression/macros.rs.html#19

The interesting one is the Level::Precise so just having access to that should give much of the customization
https://docs.rs/async-compression/latest/src/async_compression/lib.rs.html#208

Alternatives

Haven't tried it but i guess one could manually implement their own compression layer,
or do the compression in the request handler.
I believe it would be quite unnecessary to do that workaround when there's already a CompressionLayer available.

:)

[Nehliin]

PRs are welcome!

[Zerowalker]

I will try look into it, not sure i can provide code that are up to par though haha.
But i take that as it's not a bad idea, so that's a start:)

[Nehliin]

Happy to help with feedback!

[barvirm]

@Nehliin @davidpdrsn Do you have any design ideas? How propagate compression level to the encoders?
The current DecorateAsyncRead is not expandable for these changes.

[Nehliin]

Haven't looked into the details yet. Can look at it next week sometime

[barvirm]

@Nehliin Thank you

[davidpdrsn]

I think a builder method on CompressionLayer and Compression a la

CompressionLayer::new().level(the_level)

is fine.

I think we can copy https://docs.rs/async-compression/latest/async_compression/enum.Level.html into tower-http and internally map between them, to not expose things from async-compression.