7717d8fa55
* wiggle: adapt Wiggle guest slices for `unsafe` shared use When multiple threads can concurrently modify a WebAssembly shared memory, the underlying data for a Wiggle `GuestSlice` and `GuestSliceMut` could change due to access from other threads. This breaks Rust guarantees when `&[T]` and `&mut [T]` slices are handed out. This change modifies `GuestPtr` to make `as_slice` and `as_slice_mut` return an `Option` which is `None` when the underlying WebAssembly memory is shared. But WASI implementations still need access to the underlying WebAssembly memory, both to read to it and write from it. This change adds new APIs: - `GuestPtr::to_vec` copies the bytes from WebAssembly memory (from which we can safely take a `&[T]`) - `GuestPtr::as_unsafe_slice_mut` returns a wrapper `struct` from which we can `unsafe`-ly return a mutable slice (users must accept the unsafety of concurrently modifying a `&mut [T]`) This approach allows us to maintain Wiggle's borrow-checking infrastructure, which enforces the guarantee that Wiggle will not modify overlapping regions, e.g. This is important because the underlying system calls may expect this. Though other threads may modify the same underlying region, this is impossible to prevent; at least Wiggle will not be able to do so. Finally, the changes to Wiggle's API are propagated to all WASI implementations in Wasmtime. For now, code locations that attempt to get a guest slice will panic if the underlying memory is shared. Note that Wiggle is not enabled for shared memory (that will come later in something like #5054), but when it is, these panics will be clear indicators of locations that must be re-implemented in a thread-safe way. * review: remove double cast * review: refactor to include more logic in 'UnsafeGuestSlice' * review: add reference to #4203 * review: link all thread-safe WASI fixups to #5235 * fix: consume 'UnsafeGuestSlice' during conversion to safe versions * review: remove 'as_slice' and 'as_slice_mut' * review: use 'as_unsafe_slice_mut' in 'to_vec' * review: add `UnsafeBorrowResult`
wasmtime-wasi-nn
This crate enables support for the wasi-nn API in Wasmtime. Currently it contains an implementation of wasi-nn using OpenVINO™ but in the future it could support multiple machine learning backends. Since the wasi-nn API is expected to be an optional feature of WASI, this crate is currently separate from the wasi-common crate. This crate is experimental and its API, functionality, and location could quickly change.
Use
Use the Wasmtime APIs to instantiate a Wasm module and link in the WasiNn implementation as follows:
let wasi_nn = WasiNn::new(&store, WasiNnCtx::new()?);
wasi_nn.add_to_linker(&mut linker)?;
Build
This crate should build as usual (i.e. cargo build) but note that using an existing installation of OpenVINO™, rather
than building from source, will drastically improve the build times. See the openvino crate for more information
Example
An end-to-end example demonstrating ML classification is included in examples:
tests/wasi-nn-rust-bindingscontains ergonomic bindings for writing Rust code against the wasi-nn APIstests/classification-examplecontains a standalone Rust project that uses the wasi-nn APIs and is compiled to thewasm32-wasitarget using thewasi-nn-rust-bindings
Run the example from the Wasmtime project directory:
ci/run-wasi-nn-example.sh