feat: update to independent trailer retrieval

[vados-cosmonic]

No description provided.

[dicej]

LGTM, but I agree with WebAssembly/wasi-http#154 (comment) that the return type should be future<option<trailers>> rather than option<future<trailers>>.

[vados-cosmonic]

Yup, just made a comment over there -- that was more an artifact of what the Body provides -- going to write a little transpose() to push the Option in -- I'd like to avoid having to wrap in another future invocation though that would be the easiest way.

[vados-cosmonic]

Alright @dicej thanks for the feedback, this is ready now. Going to put off updating the wit completely (removing body.constructor, etc) until after upstream WIT changes and this initial PR merges!

[dicej]

LGTM. One suggestion: at the top of component-async-tests/http/src/lib.rs, we could change

    async: {
        only_imports: [
            "wasi:http/types@0.3.0-draft#[static]body.finish",
            "wasi:http/handler@0.3.0-draft#handle",
        ]
    },

to

    async: {
        only_imports: [
            "wasi:http/handler@0.3.0-draft#handle",
        ]
    },

and likewise in the wit_bindgen::generate! macro invocations in e.g. async_http_echo.rs since body.finish no longer needs to be implemented or called async.

[vados-cosmonic]

Hey @dicej I'm not sure we can do that -- since we need to create that future in the case there are no trailers -- and for that I need access to the store (which I currently get via the Accessor)

[dicej]

Hey @dicej I'm not sure we can do that -- since we need to create that future in the case there are no trailers -- and for that I need access to the store (which I currently get via the Accessor)

Good point. Let's leave the host side async but make the guest side sync, then.