perf(core): js errors as unions vs tuples to reduce allocs (denoland#…

…9947)
vinaymavi · Apr 1, 2021 · 6eace4d · 6eace4d
1 parent f8aff8e
commit 6eace4d
Show file tree

Hide file tree

Showing 2 changed files with 25 additions and 19 deletions.
diff --git a/core/core.js b/core/core.js
@@ -44,18 +44,23 @@
  }
 
  function processResponse(res) {
- // const [ok, err] = res;
- if (res[1] === null) {
- return res[0];
+ if (!isErr(res)) {
+ return res;
  }
- throw processErr(res[1]);
+ throw processErr(res);
+ }
+
+ // .$err_class_name is a special key that should only exist on errors
+ function isErr(res) {
+ return !!(res && res.$err_class_name);
  }
 
  function processErr(err) {
- const [ErrorClass, args] = getErrorClassAndArgs(err.className);
+ const className = err.$err_class_name;
+ const [ErrorClass, args] = getErrorClassAndArgs(className);
  if (!ErrorClass) {
  return new Error(
- `Unregistered error class: "${err.className}"\n ${err.message}\n Classes of errors returned from ops should be registered via Deno.core.registerErrorClass().`,
+ `Unregistered error class: "${className}"\n ${err.message}\n Classes of errors returned from ops should be registered via Deno.core.registerErrorClass().`,
  );
  }
  return new ErrorClass(err.message, ...args);
@@ -82,13 +87,12 @@
  }
 
  function opAsyncHandler(promiseId, res) {
- // const [ok, err] = res;
  const promise = promiseTable.get(promiseId);
  promiseTable.delete(promiseId);
- if (!res[1]) {
- promise.resolve(res[0]);
+ if (!isErr(res)) {
+ promise.resolve(res);
  } else {
- promise.reject(processErr(res[1]));
+ promise.reject(processErr(res));
  }
  }
 

diff --git a/core/ops.rs b/core/ops.rs
@@ -74,11 +74,16 @@ pub enum Op {
 }
 
 #[derive(Serialize)]
-pub struct OpResult<R>(Option<R>, Option<OpError>);
+#[serde(untagged)]
+pub enum OpResult<R> {
+ Ok(R),
+ Err(OpError),
+}
 
 #[derive(Serialize)]
 #[serde(rename_all = "camelCase")]
 pub struct OpError {
+ #[serde(rename = "$err_class_name")]
  class_name: &'static str,
  message: String,
 }
@@ -88,14 +93,11 @@ pub fn serialize_op_result<R: Serialize + 'static>(
  state: Rc<RefCell<OpState>>,
 ) -> OpResponse {
  OpResponse::Value(Box::new(match result {
- Ok(v) => OpResult::<R>(Some(v), None),
- Err(err) => OpResult::<R>(
- None,
- Some(OpError {
- class_name: (state.borrow().get_error_class_fn)(&err),
- message: err.to_string(),
- }),
- ),
+ Ok(v) => OpResult::Ok(v),
+ Err(err) => OpResult::Err(OpError {
+ class_name: (state.borrow().get_error_class_fn)(&err),
+ message: err.to_string(),
+ }),
  }))
 }