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https://github.com/facebook/react.git
synced 2025-11-01 09:12:30 +00:00
Andrew Clark
9b36df86c6
* Don't call idle callback unless there's time remaining * Expiration fixture Fixture that demonstrates how async work expires after a certain interval. The fixture clogs the main thread with animation work, so it only works if the `timeout` option is provided to `requestIdleCallback`. * Pass timeout option to requestIdleCallback Forces `requestIdleCallback` to fire if too much time has elapsed, even if the main thread is busy. Required to make expiration times work properly. Otherwise, async work can expire, but React never has a chance to flush it because the browser never calls into React.
57 lines
1.7 KiB
JavaScript
57 lines
1.7 KiB
JavaScript
/**
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* Copyright (c) 2013-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @flow
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*/
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import type {Deadline} from 'react-reconciler';
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const hasNativePerformanceNow =
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typeof performance === 'object' && typeof performance.now === 'function';
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const now = hasNativePerformanceNow
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? () => performance.now()
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: () => Date.now();
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type Callback = (deadline: Deadline) => void;
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let scheduledCallback: Callback | null = null;
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let frameDeadline: number = 0;
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const frameDeadlineObject: Deadline = {
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timeRemaining: () => frameDeadline - now(),
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};
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function setTimeoutCallback() {
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// TODO (bvaughn) Hard-coded 5ms unblocks initial async testing.
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// React API probably changing to boolean rather than time remaining.
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// Longer-term plan is to rewrite this using shared memory,
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// And just return the value of the bit as the boolean.
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frameDeadline = now() + 5;
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const callback = scheduledCallback;
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scheduledCallback = null;
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if (callback !== null) {
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callback(frameDeadlineObject);
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}
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}
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// RN has a poor polyfill for requestIdleCallback so we aren't using it.
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// This implementation is only intended for short-term use anyway.
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// We also don't implement cancel functionality b'c Fiber doesn't currently need it.
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function scheduleDeferredCallback(callback: Callback): number {
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// We assume only one callback is scheduled at a time b'c that's how Fiber works.
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scheduledCallback = callback;
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return setTimeout(setTimeoutCallback, 1);
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}
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function cancelDeferredCallback(callbackID: number) {
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scheduledCallback = null;
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clearTimeout(callbackID);
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}
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export {now, scheduleDeferredCallback, cancelDeferredCallback};
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