integrate scheduler.yield in SchedulerPostTask (#27069)
## Summary `scheduler.yield` is entering [Origin Trial soon in Chrome 115](https://chromestatus.com/feature/6266249336586240). This diff adds it to `SchedulerPostTask` when scheduling continuations to allow Origin Trial participation for early feedback on the new API. It seems the difference here versus the current use of `postTask` will be minor – the intent behind `scheduler.yield` seems to mostly be better ergonomics for scheduling continuations, but it may be interesting to see if the follow aspect of it results in any tangible difference in scheduling (from [here](https://github.com/WICG/scheduling-apis/blob/main/explainers/yield-and-continuation.md#introduction)): > To mitigate yielding performance penalty concerns, UAs prioritize scheduler.yield() continuations over tasks of the same priority or similar task sources. ## How did you test this change? ``` yarn test SchedulerPostTask ```
Noah Lemen committed
Jul 11, 2023 at 14:35 UTC
0a360642dcc08cab469da0a0e4f1050e56b0ef7e
2 files changed
+100
-14
packages/scheduler/src/__tests__/SchedulerPostTask-test.js
+81
-2
@@ -94,6 +94,22 @@ describe('SchedulerPostTask', () => {
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});
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};
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+ scheduler.yield = function ({priority, signal}) {
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+ const id = idCounter++;
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+ log(`Yield ${id} [${priority === undefined ? '<default>' : priority}]`);
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+ const controller = signal._controller;
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+ let callback;
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+
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+ return {
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+ then(cb) {
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+ callback = cb;
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+ return new Promise((resolve, reject) => {
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+ taskQueue.set(controller, {id, callback, resolve, reject});
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+ });
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+ },
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+ };
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+ };
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+
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global.TaskController = class TaskController {
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constructor() {
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this.signal = {_controller: this};
@@ -178,7 +194,7 @@ describe('SchedulerPostTask', () => {
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'Task 0 Fired',
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'A',
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'Yield at 5ms',
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- 'Post Task 1 [user-visible]',
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+ 'Yield 1 [user-visible]',
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]);
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runtime.flushTasks();
@@ -321,7 +337,7 @@ describe('SchedulerPostTask', () => {
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// The continuation should be scheduled in a separate macrotask even
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// though there's time remaining.
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- 'Post Task 1 [user-visible]',
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+ 'Yield 1 [user-visible]',
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]);
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// No time has elapsed
@@ -330,4 +346,67 @@ describe('SchedulerPostTask', () => {
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runtime.flushTasks();
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runtime.assertLog(['Task 1 Fired', 'Continuation Task']);
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});
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+
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+ describe('falls back to postTask for scheduling continuations when scheduler.yield is not available', () => {
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+ beforeEach(() => {
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+ delete global.scheduler.yield;
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+ });
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+
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+ it('task with continuation', () => {
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+ scheduleCallback(NormalPriority, () => {
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+ runtime.log('A');
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+ while (!Scheduler.unstable_shouldYield()) {
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+ runtime.advanceTime(1);
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+ }
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+ runtime.log(`Yield at ${performance.now()}ms`);
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+ return () => {
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+ runtime.log('Continuation');
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+ };
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+ });
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+ runtime.assertLog(['Post Task 0 [user-visible]']);
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+
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+ runtime.flushTasks();
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+ runtime.assertLog([
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+ 'Task 0 Fired',
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+ 'A',
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+ 'Yield at 5ms',
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+ 'Post Task 1 [user-visible]',
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+ ]);
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+
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+ runtime.flushTasks();
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+ runtime.assertLog(['Task 1 Fired', 'Continuation']);
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+ });
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+
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+ it('yielding continues in a new task regardless of how much time is remaining', () => {
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+ scheduleCallback(NormalPriority, () => {
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+ runtime.log('Original Task');
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+ runtime.log('shouldYield: ' + shouldYield());
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+ runtime.log('Return a continuation');
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+ return () => {
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+ runtime.log('Continuation Task');
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+ };
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+ });
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+ runtime.assertLog(['Post Task 0 [user-visible]']);
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+
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+ runtime.flushTasks();
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+ runtime.assertLog([
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+ 'Task 0 Fired',
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+ 'Original Task',
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+ // Immediately before returning a continuation, `shouldYield` returns
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+ // false, which means there must be time remaining in the frame.
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+ 'shouldYield: false',
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+ 'Return a continuation',
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+
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+ // The continuation should be scheduled in a separate macrotask even
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+ // though there's time remaining.
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+ 'Post Task 1 [user-visible]',
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+ ]);
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+
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+ // No time has elapsed
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+ expect(performance.now()).toBe(0);
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+
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+ runtime.flushTasks();
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+ runtime.assertLog(['Task 1 Fired', 'Continuation Task']);
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+ });
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+ });
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});
packages/scheduler/src/forks/SchedulerPostTask.js
+19
-12
@@ -138,18 +138,25 @@ function runTask<T>(
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// Update the original callback node's controller, since even though we're
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// posting a new task, conceptually it's the same one.
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node._controller = continuationController;
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- scheduler
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- .postTask(
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- runTask.bind(
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- null,
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- priorityLevel,
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- postTaskPriority,
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- node,
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- continuation,
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- ),
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- continuationOptions,
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- )
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- .catch(handleAbortError);
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+
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+ const nextTask = runTask.bind(
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+ null,
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+ priorityLevel,
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+ postTaskPriority,
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+ node,
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+ continuation,
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+ );
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+
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+ if (scheduler.yield !== undefined) {
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+ scheduler
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+ .yield(continuationOptions)
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+ .then(nextTask)
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+ .catch(handleAbortError);
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+ } else {
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+ scheduler
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+ .postTask(nextTask, continuationOptions)
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+ .catch(handleAbortError);
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+ }
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}
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} catch (error) {
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// We're inside a `postTask` promise. If we don't handle this error, then it