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Add support for async ABI, futures, streams, and errors #1895

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@dicej dicej commented Nov 5, 2024

This adds support for encoding and parsing components which use the Async ABI and associated canonical options and functions, along with the stream, future, and error types.

Note that the error type was recently (about 30 minutes ago) renamed to error-context in Luke's spec PR. I haven't updated this implementation to reflect that yet, but will do so in a follow-up commit. That should allow us to avoid conflicts with existing WIT files that use error as a type and/or interface name. EDIT: done

This does not yet include any new tests; I'll also add those in a follow-up commit.

See bytecodealliance/rfcs#38 for more context.

This is ready for review, but I'll leave it in draft mode until the following are complete:

  • Rename error to error-context
  • Add tests to tests/local/component-model and tests/local/missing-features to exercise new wasm-encoder, wasmparser, and wasmprinter features
  • Add tests to crates/wit-component/tests to exercise its new features
  • Add tests to crates/wit-parser/tests to exercise its new features

This adds support for encoding and parsing components which use the [Async
ABI](https://github.com/WebAssembly/component-model/blob/main/design/mvp/Async.md)
and associated canonical options and functions, along with the [`stream`,
`future`, and `error`](WebAssembly/component-model#405)
types.

Note that the `error` type was recently (about 30 minutes ago) renamed to
`error-context` in Luke's spec PR.  I haven't updated this implementation to
reflect that yet, but will do so in a follow-up commit.  That should allow us to
avoid conflicts with existing WIT files that use `error` as a type and/or
interface name.

This does not include any new tests; I'll also add those in a follow-up commit.

See bytecodealliance/rfcs#38 for more context.

Signed-off-by: Joel Dice <[email protected]>
@dicej dicej self-assigned this Nov 5, 2024
@alexcrichton alexcrichton self-requested a review November 5, 2024 23:19
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dicej commented Nov 5, 2024

Sorry about all the churn in wasm-compose; I'm currently using it for end-to-end testing, but I could switch to WAC for that and revert most of the wasm-compose changes in this PR if desired.

Also, parse string encoding and realloc from encoded `error-context.new` and
`error-context.debug-string` names.

Signed-off-by: Joel Dice <[email protected]>
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Thanks again for this! My current plan is to start tackling this the week-after-next (after WasmCon) but if you've got any high-level points you want me to confirm ahead of time feel free to let me know

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dicej commented Nov 6, 2024

Thanks again for this! My current plan is to start tackling this the week-after-next (after WasmCon) but if you've got any high-level points you want me to confirm ahead of time feel free to let me know

No hurry at all; I'm mainly opening this (and soon-to-follow PRs to wit-bindgen and wasmtime) for visibility, i.e. to allow people to track progress if they're interested. The code is still in a pretty raw state (especially the wasmtime parts 😅 ), so it's probably better if you wait a couple of weeks before looking at it, anyway.

dicej added a commit to dicej/wasmtime that referenced this pull request Nov 7, 2024
This adds support for loading, compiling, linking, and running components which
use the [Async
ABI](https://github.com/WebAssembly/component-model/blob/main/design/mvp/Async.md)
along with the [`stream`, `future`, and
`error-context`](WebAssembly/component-model#405) types.
It also adds support for generating host bindings such that multiple host
functions can be run concurrently with guest tasks -- without monopolizing the
`Store`.

See the [implementation RFC](bytecodealliance/rfcs#38)
for details, as well as [this
repo](https://github.com/dicej/component-async-demo) containing end-to-end smoke
tests.

This is very much a work-in progress, with a number of tasks remaining:

- [ ] Avoid exposing global task IDs to guests and use per-instance IDs instead
- [ ] Track `task.return` type during compilation and assert the actual and expected types match at runtime
- [ ] Ensure all guest pointers are bounds-checked when lifting, lowering, or copying values
- [ ] Reduce code duplication in `wasmtime_cranelift::compiler::component`
- [ ] Add support for `(Typed)Func::call_concurrent` per the RFC
- [ ] Add support for multiplexing stream/future reads/writes and concurrent calls to guest exports per the RFC
- [ ] Refactor, clean up, and unify handling of backpressure, yields, and even polling
- [ ] Guard against reentrance where required (e.g. in certain fused adapter calls)
- [ ] Add integration test cases covering new functionality to tests/all/component_model (starting by porting over the tests in https://github.com/dicej/component-async-demo)
- [ ] Add binding generation test cases to crates/component-macro/tests
- [ ] Add WAST tests to tests/misc_testsuite/component-model
- [ ] Add support and test coverage for callback-less async functions (e.g. goroutines)
- [ ] Switch to back to upstream `wasm-tools` once bytecodealliance/wasm-tools#1895 has been merged and released

Signed-off-by: Joel Dice <[email protected]>
dicej added a commit to dicej/wasmtime that referenced this pull request Nov 7, 2024
This adds support for loading, compiling, linking, and running components which
use the [Async
ABI](https://github.com/WebAssembly/component-model/blob/main/design/mvp/Async.md)
along with the [`stream`, `future`, and
`error-context`](WebAssembly/component-model#405) types.
It also adds support for generating host bindings such that multiple host
functions can be run concurrently with guest tasks -- without monopolizing the
`Store`.

See the [implementation RFC](bytecodealliance/rfcs#38)
for details, as well as [this
repo](https://github.com/dicej/component-async-demo) containing end-to-end smoke
tests.

This is very much a work-in progress, with a number of tasks remaining:

- [ ] Avoid exposing global task IDs to guests and use per-instance IDs instead
- [ ] Track `task.return` type during compilation and assert the actual and expected types match at runtime
- [ ] Ensure all guest pointers are bounds-checked when lifting, lowering, or copying values
- [ ] Reduce code duplication in `wasmtime_cranelift::compiler::component`
- [ ] Reduce code duplication between `StoreContextMut::on_fiber` and `concurrent::on_fiber`
- [ ] Minimize and/or document the use of unsafe code
- [ ] Add support for `(Typed)Func::call_concurrent` per the RFC
- [ ] Add support for multiplexing stream/future reads/writes and concurrent calls to guest exports per the RFC
- [ ] Refactor, clean up, and unify handling of backpressure, yields, and even polling
- [ ] Guard against reentrance where required (e.g. in certain fused adapter calls)
- [ ] Add integration test cases covering new functionality to tests/all/component_model (starting by porting over the tests in https://github.com/dicej/component-async-demo)
- [ ] Add binding generation test cases to crates/component-macro/tests
- [ ] Add WAST tests to tests/misc_testsuite/component-model
- [ ] Add support and test coverage for callback-less async functions (e.g. goroutines)
- [ ] Switch to back to upstream `wasm-tools` once bytecodealliance/wasm-tools#1895 has been merged and released

Signed-off-by: Joel Dice <[email protected]>
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