wiggle: choose between &mut self and &self
#5428
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Previously, all Wiggle-generated traits were generated with `&mut self` signatures. With the addition of the `mutable` configuration option to `from_witx!` and `wasmtime_integration!`, one can disable this, emitting instead traits that use `&self` (i.e., `mutable: false`). This change is helpful for implementing wasi-threads: WASI implementations with interior mutability will now be able to communitcate this to their Wiggle-generated code. The other side of this change is the `get_cx` closure passed to Wiggle's generated `add_to_linker` function. When `mutability` is set to `true` (default), the `get_cx` function takes a `&mut` data structure from the store and returns a corresponding `&mut` reference, usually to a field of the passed-in structure. When `mutability: false`, the `get_cx` closure will still take a `&mut` data structure but now will return a `&` reference.
alexcrichton
approved these changes
Dec 13, 2022
abrown
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Dec 20, 2022
After bytecodealliance#5236, it is now easier to modify the `wasi-common` implementations (both `preview0` and `preview1`) to use `&self` instead of `&mut self` in their function signatures. This makes it possible to access and use a `WasiCtx` from an `Arc<Host>` (the top-level Wasmtime CLI structure holding the WASI implementations). An `Arc<Host>` will only give out immutable access to the WASI implementations it contains. This relies on bytecodealliance#5428 to configure Wiggle to emit `&self`-receiving traits. This change also wraps `wasi-common`'s source of randomness in `WasiCtx` with a `Mutex` to enable this `&mut self` to `&self` refactoring. One remaining issue to figure out with this change is the interaction with the `async` side of wiggle. E.g., `cargo build --all-features -p wasmtime-wasi` will fail due to the `tokyo` feature being enabled. The errors have to do with incorrect `Send` and `Sync` bounds on various parts of the Wiggle-generated API. We had previously discussed turning off these `async` parts when the `wasi-threads` feature is enabled, or at least prevent these features from being enabled at the same time, since as-is even `cargo test --all` is affected.
abrown
added a commit
to abrown/wasmtime
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Jan 6, 2023
After bytecodealliance#5236, it is now easier to modify the `wasi-common` implementations (both `preview0` and `preview1`) to use `&self` instead of `&mut self` in their function signatures. This makes it possible to access and use a `WasiCtx` from an `Arc<Host>` (the top-level Wasmtime CLI structure holding the WASI implementations). An `Arc<Host>` will only give out immutable access to the WASI implementations it contains. This relies on bytecodealliance#5428 to configure Wiggle to emit `&self`-receiving traits. This change also wraps `wasi-common`'s source of randomness in `WasiCtx` with a `Mutex` to enable this `&mut self` to `&self` refactoring. One remaining issue to figure out with this change is the interaction with the `async` side of wiggle. E.g., `cargo build --all-features -p wasmtime-wasi` will fail due to the `tokyo` feature being enabled. The errors have to do with incorrect `Send` and `Sync` bounds on various parts of the Wiggle-generated API. We had previously discussed turning off these `async` parts when the `wasi-threads` feature is enabled, or at least prevent these features from being enabled at the same time, since as-is even `cargo test --all` is affected.
abrown
added a commit
to abrown/wasmtime
that referenced
this pull request
Jan 9, 2023
After bytecodealliance#5236, it is now easier to modify the `wasi-common` implementations (both `preview0` and `preview1`) to use `&self` instead of `&mut self` in their function signatures. This makes it possible to access and use a `WasiCtx` from an `Arc<Host>` (the top-level Wasmtime CLI structure holding the WASI implementations). An `Arc<Host>` will only give out immutable access to the WASI implementations it contains. This relies on bytecodealliance#5428 to configure Wiggle to emit `&self`-receiving traits. This change also wraps `wasi-common`'s source of randomness in `WasiCtx` with a `Mutex` to enable this `&mut self` to `&self` refactoring. One remaining issue to figure out with this change is the interaction with the `async` side of wiggle. E.g., `cargo build --all-features -p wasmtime-wasi` will fail due to the `tokyo` feature being enabled. The errors have to do with incorrect `Send` and `Sync` bounds on various parts of the Wiggle-generated API. We had previously discussed turning off these `async` parts when the `wasi-threads` feature is enabled, or at least prevent these features from being enabled at the same time, since as-is even `cargo test --all` is affected.
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Previously, all Wiggle-generated traits were generated with
&mut selfsignatures. With the addition of themutableconfiguration option tofrom_witx!andwasmtime_integration!, one can disable this, emitting instead traits that use&self(i.e.,mutable: false). This change is helpful for implementing wasi-threads: WASI implementations with interior mutability will now be able to communitcate this to their Wiggle-generated code.The other side of this change is the
get_cxclosure passed to Wiggle's generatedadd_to_linkerfunction. Whenmutabilityis set totrue(default), theget_cxfunction takes a&mutdata structure from the store and returns a corresponding&mutreference, usually to a field of the passed-in structure. Whenmutability: false, theget_cxclosure will still take a&mutdata structure but now will return a&reference.