denoland-deno/ops/README.md

deno_ops

proc_macro for generating highly optimized V8 functions from Deno ops.

// Declare an op.
#[op]
pub fn op_add(_: &mut OpState, a: i32, b: i32) -> Result<i32, AnyError> {
  Ok(a + b)
}

// Register with an extension.
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 can 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.