feat(ext/http): auto-compression of fixed response bodies

[kitsonk]

Work in progress from a pairing session between myself and @ry

Inspired by previous work of @satyarohith on Deno Deploy.

[lucacasonato]

This is looking great! @kitsonk what do you think about adding an option to disable this behaviour to a Deno.serveHttp options bag?

[lucacasonato]

Also do we need to have special handling for Range?

[kitsonk]

This is looking great! @kitsonk what do you think about adding an option to disable this behaviour to a Deno.serveHttp options bag?

I thought about it when I paired with @ry and he argued against it. It does add complexity to it. Is there a compelling case where someone would want to disable it, other than "because they can"? Doesn't setting Cache-Control: no-transform effectively provide that functionality without adding to the API surface? That is how CFW supports disabling it.

[lucacasonato]

I could imagine that one has an nginx in front of Deno that is responsible for on the fly encoding. In that case you want Deno to leave the responses as "pure" as possible. I don't think we per-se need to add this for the PR to land, but I think it would be useful to give users an opt-out. The implementation complexity seems rather trivial.

[kitsonk]

Also do we need to have special handling for Range?

Actually, after doing a bit of research, if a Content-Range header is present in the response, we should disable automatic compression, as the user HTTP server has processed a range request, with the range being based off the uncompressed range headers it negotiated.

[lucacasonato]

LGTM

@satyarohith PTAL too

[satyarohith]

Nit: there are some new additions to https://github.com/jshttp/mime-db/blob/master/db.json; we might want to update the list.

feel free to skip it

[kitsonk]

Let's skip it for now, as they are very likely very esoteric media types that aren't widely used.

Longer term, someone should either find an efficient way to statically include the JSON in, or generate the code statically from the JSON file.

[satyarohith]

LGTM.

Thanks for working on it! :)