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Diffstat (limited to 'ops/README.md')
| -rw-r--r-- | ops/README.md | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/ops/README.md b/ops/README.md index 02ee266f7..b9114b554 100644 --- a/ops/README.md +++ b/ops/README.md @@ -4,9 +4,9 @@ ```rust // Declare an op. -#[op] -pub fn op_add(_: &mut OpState, a: i32, b: i32) -> Result<i32, AnyError> { - Ok(a + b) +#[op(fast)] +pub fn op_add(_: &mut OpState, a: i32, b: i32) -> i32 { + a + b } // Register with an extension. @@ -14,3 +14,31 @@ Extension::builder() .ops(vec![op_add::decl()]) .build(); ``` + +## Peformance + +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 / `&mut OpState` +- return_type: integers + +The `#[op(fast)]` attribute shoukd 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. |