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Disable Just Noticeable Difference heuristic #15423

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Disable Just Noticeable Difference heuristic #15423

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52 changes: 21 additions & 31 deletions packages/react-reconciler/src/ReactFiberScheduler.js
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Original file line number Diff line number Diff line change
Expand Up @@ -160,8 +160,6 @@ import {
} from 'shared/ReactErrorUtils';
import {onCommitRoot} from './ReactFiberDevToolsHook';

const ceil = Math.ceil;

const {
ReactCurrentDispatcher,
ReactCurrentOwner,
Expand Down Expand Up @@ -1819,6 +1817,8 @@ export function resolveRetryThenable(boundaryFiber: Fiber, thenable: Thenable) {
retryTimedOutBoundary(boundaryFiber);
}

// FIXME: This change resulted in bugs during internal testing. I've reverted
// it temporarily. Figure out why before landing again.
// Computes the next Just Noticeable Difference (JND) boundary.
// The theory is that a person can't tell the difference between small differences in time.
// Therefore, if we wait a bit longer than necessary that won't translate to a noticeable
Expand All @@ -1828,21 +1828,21 @@ export function resolveRetryThenable(boundaryFiber: Fiber, thenable: Thenable) {
// the longer we can wait additionally. At some point we have to give up though.
// We pick a train model where the next boundary commits at a consistent schedule.
// These particular numbers are vague estimates. We expect to adjust them based on research.
function jnd(timeElapsed: number) {
return timeElapsed < 120
? 120
: timeElapsed < 480
? 480
: timeElapsed < 1080
? 1080
: timeElapsed < 1920
? 1920
: timeElapsed < 3000
? 3000
: timeElapsed < 4320
? 4320
: ceil(timeElapsed / 1960) * 1960;
}
// function jnd(timeElapsed: number) {
// return timeElapsed < 120
// ? 120
// : timeElapsed < 480
// ? 480
// : timeElapsed < 1080
// ? 1080
// : timeElapsed < 1920
// ? 1920
// : timeElapsed < 3000
// ? 3000
// : timeElapsed < 4320
// ? 4320
// : ceil(timeElapsed / 1960) * 1960;
// }

function computeMsUntilTimeout(
mostRecentEventTime: ExpirationTime,
Expand All @@ -1857,21 +1857,11 @@ function computeMsUntilTimeout(
const currentTimeMs: number = now();
const timeElapsed = currentTimeMs - eventTimeMs;

let msUntilTimeout = jnd(timeElapsed) - timeElapsed;

// Compute the time until this render pass would expire.
const timeUntilExpirationMs =
expirationTimeToMs(committedExpirationTime) + initialTimeMs - currentTimeMs;

// Clamp the timeout to the expiration time.
// TODO: Once the event time is exact instead of inferred from expiration time
// we don't need this.
if (timeUntilExpirationMs < msUntilTimeout) {
msUntilTimeout = timeUntilExpirationMs;
}

// TODO: Account for the Just Noticeable Difference
const timeoutMs = 150;
const msUntilTimeout = timeoutMs - timeElapsed;
// This is the value that is passed to `setTimeout`.
return msUntilTimeout;
return msUntilTimeout < 0 ? 0 : msUntilTimeout;
}

function checkForNestedUpdates() {
Expand Down
14 changes: 3 additions & 11 deletions packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.internal.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1568,7 +1568,7 @@ describe('ReactSuspenseWithNoopRenderer', () => {
);
});

it('suspends for longer if something took a long (CPU bound) time to render', async () => {
it.skip('suspends for longer if something took a long (CPU bound) time to render', async () => {
function Foo() {
Scheduler.yieldValue('Foo');
return (
Expand Down Expand Up @@ -1618,7 +1618,7 @@ describe('ReactSuspenseWithNoopRenderer', () => {
expect(ReactNoop.getChildren()).toEqual([span('A')]);
});

it('suspends for longer if a fallback has been shown for a long time', async () => {
it.skip('suspends for longer if a fallback has been shown for a long time', async () => {
function Foo() {
Scheduler.yieldValue('Foo');
return (
Expand Down Expand Up @@ -1688,7 +1688,7 @@ describe('ReactSuspenseWithNoopRenderer', () => {
expect(ReactNoop.getChildren()).toEqual([span('A'), span('B')]);
});

it('does not suspend for very long after a higher priority update', async () => {
it.skip('does not suspend for very long after a higher priority update', async () => {
function Foo() {
Scheduler.yieldValue('Foo');
return (
Expand Down Expand Up @@ -1724,11 +1724,3 @@ describe('ReactSuspenseWithNoopRenderer', () => {
expect(ReactNoop.getChildren()).toEqual([span('Loading...')]);
});
});

// TODO:
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@acdlite acdlite Apr 15, 2019

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This is unrelated; deleting because I noticed it and they are outdated.

// An update suspends, timeout is scheduled. Update again with different timeout.
// An update suspends, a higher priority update also suspends, each has different timeouts.
// Can update siblings of a timed out placeholder without suspending
// Pinging during the render phase
// Synchronous thenable
// Start time is computed using earliest suspended time