feat(wasm): add support for wasip2, aka webassembly components, using `wasi-http` #2290

brooksmtownsend · 2024-05-17T13:04:04Z

Draft as this depends on servo/rust-url#960

Should resolve the below comment re: future polling

Hey there! This is a work-in-progress PR that adds support for using reqwest with wasi-http. It was really neat to see the support for wasm_bindgen and JavaScript bindings for requests, and this PR helps support the component model in addition to wasm_bindgen.

I wanted to open this PR to see if you had any suggestions, requests from the initial working code/refactor perspective, and if there's any additional material you'd like me to clarify. If this fits within your general contribution guidelines, I'll wrap it up and mark as ready for review!

This code is still very littered with unwraps and comments, so go easy on me if you take a look at the implementation 😅 . To name a few, here's the things I want to do still for this PR:

General code cleanliness, no doc comments simply added as dox, kill unwraps, expects, and panics
Add example that I'm using for testing under the examples dir
Gate wit-bindgen behind the wasm32 family of deps
See if I can better toggle between the JS/bindgen Wasm support and the component model wasm support using directives instead of a feature (there is the wasm32-wasip2 target but that's not very widely used yet.) The goal here is to not affect any existing use cases of wasm -> reqwest and add support for components.
Consider a custom pollable to remove the technically blocking code in the request

Last but not least, thanks for this library! Love reqwest ❤️

seanmonstar · 2024-05-17T14:03:27Z

Thanks for taking a look at this! I think support WASI is likely a good goal, in general. However, I usually try to have the discussion in an issue first. I find it's helpful to find consensus before spending too much time going down a certain implementation path, or even working on a feature that won't be accepted at all.

So while I do appreciate exploring the area, and exploration is often needed to inform more complex features, I do want to set proper expectations: we might not do this, or do it very differently. 🙈

brooksmtownsend · 2024-05-17T14:23:54Z

@seanmonstar that's why I opened the draft PR! Glad I ended up doing that before I got too far down the road. I can open up an issue then and point at this branch as a reference if that's what you prefer

brooksmtownsend · 2024-05-17T14:29:16Z

Oh fun, #1956 and #1977 exist. Do we need another issue? Looks like the implementation in #1956 is also an option for comparison, albeit not quite on [email protected].

brooksmtownsend · 2024-05-20T16:26:59Z

Created #2294 to further the discussion, @seanmonstar please feel free to either close this PR for now while we continue in the issue or leave it open, totally up to the way you like to track the OSS work.

brooksmtownsend · 2024-05-22T16:33:51Z

Rebased this PR off of main and added a component example so folks can see this in action. With reqwest it is really nice looking

pimeys · 2024-07-29T09:48:27Z

Hey. I've been playing around with reqwest, tokio and wasm components, and presented a bit of a demo to a customer how to use these together. You might want to check and pull some of my changes. I implemented async response handling and my fork can now also send a body with the request.

https://github.com/pimeys/reqwest/tree/feat/wasi-p2-component-support

Any comments and ideas are welcome, and I might also join the effort later on to get this to the mainline. We just need the functionality now, so took your code and modified it a bit.

brooksmtownsend · 2024-07-29T14:43:54Z

Thanks @pimeys ! I'll have to take a look at your implementation. I was honestly considering making the component implementation blocking/sync for now, since wasi-http doesn't have any native async.

I'm happy to integrate any improvements into this fork

pimeys · 2024-07-29T15:10:14Z

Wait... There is enough functionality to make it work. I measured a tokio join to an endpoint with your original PR and with my changes to an endpoint with a steady 1s response time.

Mine was 1s and yours 3s for three concurrent requests.

The wit definitions do have async versions of the needed apis.

pimeys · 2024-07-29T15:55:10Z

This here allows async writing of body in the request:

https://github.com/pimeys/reqwest/blob/feat/wasi-p2-component-support/src/wasm/component/wit/deps/io/streams.wit#L117-L132

This one here after a request is done returns a future of a response:

https://github.com/pimeys/reqwest/blob/feat/wasi-p2-component-support/src/wasm/component/wit/deps/http/types.wit#L551

Which can be polled in a non-blocking way, and then determined if the response is received or not.

Edit: I based my changes to your branch @brooksmtownsend, so you should be able to rebase my changes if you want.

brooksmtownsend · 2024-07-31T13:58:55Z

@pimeys do you have an example component that you used with these changes?

pimeys · 2024-07-31T17:30:00Z

Here's one

https://github.com/grafbase/grafbase/tree/main/examples/gateway-hooks

brooksmtownsend · 2024-07-31T17:48:34Z

The wit definitions do have async versions of the needed apis.

Yep! You're correct, all I meant to say was that currently functions that you can export with components have to be sync, so it requires either blocking with an async runtime or executor. So I was considering making this sync to make the API easier, but I think it's a common enough operation in Rust to do this.

Looking at brooksmtownsend/reqwest@feat/wasi-p2-component-support...pimeys:reqwest:feat/wasi-p2-component-support it looks slick, I may just take it entirely!

pimeys · 2024-08-02T13:34:32Z

So what wasmtime does here is they have so called co-operative execution of the guest function. You can either use fuel or implement an epoch based yielding with it. This means you can run a tokio runtime with guest components, which will block but wasmtime yields every now and then and lets other futures execute things while going.

If you want async execution in a guest component, you will need a second runtime. We have some customers that expect to run async http requests in the guest code, so we really need an http client for Rust that can do that. And, luckily it is not that hard to implement!

Signed-off-by: Brooks Townsend <[email protected]> refactor(wasm): add wasm mod Signed-off-by: Brooks Townsend <[email protected]>

Signed-off-by: Brooks Townsend <[email protected]> wip: feat(wasm): add component feature Signed-off-by: Brooks Townsend <[email protected]>

Signed-off-by: Brooks Townsend <[email protected]>

brooksmtownsend · 2024-08-15T17:08:29Z

@pimeys curious if you have any recommendations for 33aa9d7, I've pulled in your changes but unfortunately for the component included I wasn't able to actually use the async support you added, the future was just polled in a hot loop. The sleep isn't ideal and I'm wondering if you get the same result as me, but I assume your example worked.

I updated the example included to build using the nightly target wasm32-wasip2 and the wasi crate, which removes the need to use generated WIT bindings in the component or the crate. I also pushed a refactor that removed some of the extra implementations that weren't correct or necessary here, like multipart, in order to simplify the initial review process. We can certainly add that back in as necessary

brooksmtownsend · 2024-08-19T13:27:32Z

src/wasm/component/client/future.rs

+                    // NOTE(brooksmtownsend): We shouldn't be waking here since we don't know that
+                    // the future is ready to be polled again. Sleeping for a nanosecond appears to
+                    // allow the future to be polled again without causing a busy loop.
+                    std::thread::sleep(std::time::Duration::from_nanos(1));
+                    cx.waker().wake_by_ref();
+                    return Poll::Pending;


This sleep is the only part of this PR that needs to be addressed before review. We should consider storing the waker & using a background task to wait for the future to be ready before waking the context. Not sleeping for a nanosecond here will infinitely hot-loop polling the future

Signed-off-by: Brooks Townsend <[email protected]>

Signed-off-by: Brooks Townsend <[email protected]> feat(wasm): update component to use wasip2 target Signed-off-by: Brooks Townsend <[email protected]> feat(wasm): update component to use wasip2 target Signed-off-by: Brooks Townsend <[email protected]>

Signed-off-by: Brooks Townsend <[email protected]>

Signed-off-by: Brooks Townsend <[email protected]> io::copy instead of streams Signed-off-by: Brooks Townsend <[email protected]>

Signed-off-by: Brooks Townsend <[email protected]>

brooksmtownsend force-pushed the feat/wasi-p2-component-support branch from 9d87534 to 2811301 Compare May 17, 2024 14:29

brooksmtownsend mentioned this pull request May 20, 2024

Support WebAssembly Component bindings, aka wasip2, in addition to javascript bindings #2294

Open

brooksmtownsend force-pushed the feat/wasi-p2-component-support branch 2 times, most recently from 7a17bbe to f623025 Compare May 22, 2024 16:33

brooksmtownsend force-pushed the feat/wasi-p2-component-support branch from f623025 to b083bbd Compare May 22, 2024 16:50

brooksmtownsend and others added 7 commits August 15, 2024 13:03

refactor(wasm): move wasm_bindgen support to js folder

5086398

Signed-off-by: Brooks Townsend <[email protected]> refactor(wasm): add wasm mod Signed-off-by: Brooks Townsend <[email protected]>

feat(wasm): add wasip2 component support

ea2473e

Signed-off-by: Brooks Townsend <[email protected]> wip: feat(wasm): add component feature Signed-off-by: Brooks Townsend <[email protected]>

chore(wasm): add wasip2 component example

3b4569c

Signed-off-by: Brooks Townsend <[email protected]>

fix: make request async

c3b687c

fix: try to write the request body

46965b9

chore: simplify body state machine

f708de8

fix: proper bytes handling for larger bodies

b7c418b

brooksmtownsend force-pushed the feat/wasi-p2-component-support branch from 393e7a5 to 33aa9d7 Compare August 15, 2024 17:03

brooksmtownsend force-pushed the feat/wasi-p2-component-support branch from 33aa9d7 to bfd1d9d Compare August 15, 2024 17:09

brooksmtownsend mentioned this pull request Aug 15, 2024

fix: enable wasip2 feature for wasm32-wasip2 target servo/rust-url#960

Merged

brooksmtownsend force-pushed the feat/wasi-p2-component-support branch from bfd1d9d to 093c1cb Compare August 15, 2024 18:53

brooksmtownsend commented Aug 19, 2024

View reviewed changes

brooksmtownsend force-pushed the feat/wasi-p2-component-support branch 2 times, most recently from 7d636e2 to 3ef4eb4 Compare August 21, 2024 21:04

pimeys and others added 6 commits August 22, 2024 11:47

fix: make big bodies to send correctly

975bd9c

Signed-off-by: Brooks Townsend <[email protected]>

pin to 0.13.1

6993585

Signed-off-by: Brooks Townsend <[email protected]>

chore: add .vscode to .gitignore

b0c6e1b

Signed-off-by: Brooks Townsend <[email protected]>

feat(wasm): allow streaming incoming body

ff8a364

Signed-off-by: Brooks Townsend <[email protected]> io::copy instead of streams Signed-off-by: Brooks Townsend <[email protected]>

refactor(wasm): remove extra component implementations

04e8b94

Signed-off-by: Brooks Townsend <[email protected]>

brooksmtownsend force-pushed the feat/wasi-p2-component-support branch from 3ef4eb4 to 04e8b94 Compare August 22, 2024 15:47

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feat(wasm): add support for wasip2, aka webassembly components, using `wasi-http` #2290

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feat(wasm): add support for wasip2, aka webassembly components, using `wasi-http` #2290

feat(wasm): add support for wasip2, aka webassembly components, using `wasi-http` #2290

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