SchedulerPostTask.js — react Source File

Source Code

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */

import type {PriorityLevel} from '../SchedulerPriorities';

declare class TaskController {
  constructor(options?: {priority?: string}): TaskController;
  signal: mixed;
  abort(): void;
}

type PostTaskPriorityLevel = 'user-blocking' | 'user-visible' | 'background';

type CallbackNode = {
  _controller: TaskController,
};

import {
  ImmediatePriority,
  UserBlockingPriority,
  NormalPriority,
  LowPriority,
  IdlePriority,
} from '../SchedulerPriorities';

export {
  ImmediatePriority as unstable_ImmediatePriority,
  UserBlockingPriority as unstable_UserBlockingPriority,
  NormalPriority as unstable_NormalPriority,
  IdlePriority as unstable_IdlePriority,
  LowPriority as unstable_LowPriority,
};

// Capture local references to native APIs, in case a polyfill overrides them.
const perf = window.performance;
const setTimeout = window.setTimeout;

// Use experimental Chrome Scheduler postTask API.
const scheduler = global.scheduler;

const getCurrentTime: () => DOMHighResTimeStamp = perf.now.bind(perf);

export const unstable_now = getCurrentTime;

// Scheduler periodically yields in case there is other work on the main
// thread, like user events. By default, it yields multiple times per frame.
// It does not attempt to align with frame boundaries, since most tasks don't
// need to be frame aligned; for those that do, use requestAnimationFrame.
const yieldInterval = 5;
let deadline = 0;

let currentPriorityLevel_DEPRECATED: PriorityLevel = NormalPriority;

// Always yield at the end of the frame.
// ... (179 more lines)