mirror of
https://github.com/denoland/deno.git
synced 2024-11-27 16:10:57 -05:00
ca66978a5a
This PR introduces Wasm ops. These calls are optimized for entry from
Wasm land.
The `#[op(wasm)]` attribute is opt-in.
Last parameter `Option<&mut [u8]>` is the memory slice of the Wasm
module *when entered from a Fast API call*. Otherwise, the user is
expected to implement logic to obtain the memory if `None`
```rust
#[op(wasm)]
pub fn op_args_get(
offset: i32,
buffer_offset: i32,
memory: Option<&mut [u8]>,
) {
// ...
}
```
62 lines
1.6 KiB
Markdown
62 lines
1.6 KiB
Markdown
# deno_ops
|
|
|
|
`proc_macro` for generating highly optimized V8 functions from Deno ops.
|
|
|
|
```rust
|
|
// Declare an op.
|
|
#[op(fast)]
|
|
pub fn op_add(_: &mut OpState, a: i32, b: i32) -> i32 {
|
|
a + b
|
|
}
|
|
|
|
// Register with an extension.
|
|
Extension::builder()
|
|
.ops(vec![op_add::decl()])
|
|
.build();
|
|
```
|
|
|
|
## Performance
|
|
|
|
The macro can optimize away code, short circuit fast paths and generate a Fast
|
|
API impl.
|
|
|
|
Cases where code is optimized away:
|
|
|
|
- `-> ()` skips serde_v8 and `rv.set` calls.
|
|
- `-> Result<(), E>` skips serde_v8 and `rv.set` calls for `Ok()` branch.
|
|
- `-> ResourceId` or `-> [int]` types will use specialized method like
|
|
`v8::ReturnValue::set_uint32`. A fast path for SMI.
|
|
- `-> Result<ResourceId, E>` or `-> Result<[int], E>` types will be optimized
|
|
like above for the `Ok()` branch.
|
|
|
|
### Fast calls
|
|
|
|
The macro will infer and try to auto generate V8 fast API call trait impl for
|
|
`sync` ops with:
|
|
|
|
- arguments: integers, bool, `&mut OpState`, `&[u8]`, `&mut [u8]`, `&[u32]`,
|
|
`&mut [u32]`
|
|
- return_type: integers, bool
|
|
|
|
The `#[op(fast)]` attribute should be used to enforce fast call generation at
|
|
compile time.
|
|
|
|
Trait gen for `async` ops & a ZeroCopyBuf equivalent type is planned and will be
|
|
added soon.
|
|
|
|
### Wasm calls
|
|
|
|
The `#[op(wasm)]` attribute should be used for calls expected to be called from
|
|
Wasm. This enables the fast call generation and allows seamless `WasmMemory`
|
|
integration for generic and fast calls.
|
|
|
|
```rust
|
|
#[op(wasm)]
|
|
pub fn op_args_get(
|
|
offset: i32,
|
|
buffer_offset: i32,
|
|
memory: Option<&[u8]>, // Must be last parameter. Some(..) when entered from Wasm.
|
|
) {
|
|
// ...
|
|
}
|
|
```
|