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Reused components commit with timing as new ones
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When an Offscreen tree goes from hidden -> visible, the tree may include
both reused components that were unmounted when the tree was hidden, and
also brand new components that didn't exist in the hidden tree.

Currently when this happens, we commit all the reused components'
effects first, before committing the new ones, using two separate
traversals of the tree.

Instead, we should fire all the effects with the same timing as if it
were a completely new tree. See the test I wrote for an example.

This is also more efficient because we only need to traverse the
tree once.
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@acdlite
acdlite committed Jul 19, 2022
1 parent 679eea3 commit cfb6cfa
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Showing 3 changed files with 489 additions and 194 deletions.
256 changes: 159 additions & 97 deletions packages/react-reconciler/src/ReactFiberCommitWork.new.js
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Original file line number Diff line number Diff line change
Expand Up @@ -225,18 +225,6 @@ const callComponentWillUnmountWithTimer = function(current, instance) {
}
};

// Capture errors so they don't interrupt mounting.
function safelyCallCommitHookLayoutEffectListMount(
current: Fiber,
nearestMountedAncestor: Fiber | null,
) {
try {
commitHookEffectListMount(HookLayout, current);
} catch (error) {
captureCommitPhaseError(current, nearestMountedAncestor, error);
}
}

// Capture errors so they don't interrupt unmounting.
function safelyCallComponentWillUnmount(
current: Fiber,
Expand All @@ -250,19 +238,6 @@ function safelyCallComponentWillUnmount(
}
}

// Capture errors so they don't interrupt mounting.
function safelyCallComponentDidMount(
current: Fiber,
nearestMountedAncestor: Fiber | null,
instance: any,
) {
try {
instance.componentDidMount();
} catch (error) {
captureCommitPhaseError(current, nearestMountedAncestor, error);
}
}

// Capture errors so they don't interrupt mounting.
function safelyAttachRef(current: Fiber, nearestMountedAncestor: Fiber | null) {
try {
Expand Down Expand Up @@ -706,7 +681,7 @@ export function commitPassiveEffectDurations(
}
}

function commitHookLayoutEffects(finishedWork: Fiber) {
function commitHookLayoutEffects(finishedWork: Fiber, hookFlags: HookFlags) {
// At this point layout effects have already been destroyed (during mutation phase).
// This is done to prevent sibling component effects from interfering with each other,
// e.g. a destroy function in one component should never override a ref set
Expand All @@ -718,14 +693,14 @@ function commitHookLayoutEffects(finishedWork: Fiber) {
) {
try {
startLayoutEffectTimer();
commitHookEffectListMount(HookLayout | HookHasEffect, finishedWork);
commitHookEffectListMount(hookFlags, finishedWork);
} catch (error) {
captureCommitPhaseError(finishedWork, finishedWork.return, error);
}
recordLayoutEffectDuration(finishedWork);
} else {
try {
commitHookEffectListMount(HookLayout | HookHasEffect, finishedWork);
commitHookEffectListMount(hookFlags, finishedWork);
} catch (error) {
captureCommitPhaseError(finishedWork, finishedWork.return, error);
}
Expand Down Expand Up @@ -853,7 +828,7 @@ function commitClassLayoutLifecycles(
}
}

function commitClassCallbacks(finishedWork: Fiber, current: Fiber | null) {
function commitClassCallbacks(finishedWork: Fiber) {
// TODO: I think this is now always non-null by the time it reaches the
// commit phase. Consider removing the type check.
const updateQueue: UpdateQueue<*> | null = (finishedWork.updateQueue: any);
Expand Down Expand Up @@ -897,7 +872,7 @@ function commitClassCallbacks(finishedWork: Fiber, current: Fiber | null) {
}
}

function commitHostComponentMount(finishedWork: Fiber, current: Fiber | null) {
function commitHostComponentMount(finishedWork: Fiber) {
const type = finishedWork.type;
const props = finishedWork.memoizedProps;
const instance: Instance = finishedWork.stateNode;
Expand Down Expand Up @@ -978,6 +953,8 @@ function commitLayoutEffectOnFiber(
finishedWork: Fiber,
committedLanes: Lanes,
): void {
// When updating this function, also update reappearLayoutEffects, which does
// most of the same things when an offscreen tree goes from hidden -> visible.
const flags = finishedWork.flags;
switch (finishedWork.tag) {
case FunctionComponent:
Expand All @@ -989,9 +966,7 @@ function commitLayoutEffectOnFiber(
committedLanes,
);
if (flags & Update) {
if (!offscreenSubtreeWasHidden) {
commitHookLayoutEffects(finishedWork);
}
commitHookLayoutEffects(finishedWork, HookLayout | HookHasEffect);
}
break;
}
Expand All @@ -1002,19 +977,15 @@ function commitLayoutEffectOnFiber(
committedLanes,
);
if (flags & Update) {
if (!offscreenSubtreeWasHidden) {
commitClassLayoutLifecycles(finishedWork, current);
}
commitClassLayoutLifecycles(finishedWork, current);
}

if (flags & Callback) {
commitClassCallbacks(finishedWork, current);
commitClassCallbacks(finishedWork);
}

if (flags & Ref) {
if (!offscreenSubtreeWasHidden) {
safelyAttachRef(finishedWork, finishedWork.return);
}
safelyAttachRef(finishedWork, finishedWork.return);
}
break;
}
Expand Down Expand Up @@ -1063,13 +1034,11 @@ function commitLayoutEffectOnFiber(
// These effects should only be committed when components are first mounted,
// aka when there is no current/alternate.
if (current === null && flags & Update) {
commitHostComponentMount(finishedWork, current);
commitHostComponentMount(finishedWork);
}

if (flags & Ref) {
if (!offscreenSubtreeWasHidden) {
safelyAttachRef(finishedWork, finishedWork.return);
}
safelyAttachRef(finishedWork, finishedWork.return);
}
break;
}
Expand Down Expand Up @@ -1117,19 +1086,25 @@ function commitLayoutEffectOnFiber(
offscreenSubtreeWasHidden = newOffscreenSubtreeWasHidden;

if (offscreenSubtreeWasHidden && !prevOffscreenSubtreeWasHidden) {
// This is the root of a reappearing boundary. Turn its layout
// effects back on.
recursivelyTraverseReappearLayoutEffects(finishedWork);
// This is the root of a reappearing boundary. As we continue
// traversing the layout effects, we must also re-mount layout
// effects that were unmounted when the Offscreen subtree was
// hidden. So this is a superset of the normal commitLayoutEffects.
const includeWorkInProgressEffects =
(finishedWork.subtreeFlags & LayoutMask) !== NoFlags;
recursivelyTraverseReappearLayoutEffects(
finishedRoot,
finishedWork,
committedLanes,
includeWorkInProgressEffects,
);
} else {
recursivelyTraverseLayoutEffects(
finishedRoot,
finishedWork,
committedLanes,
);
}

// TODO: We shouldn't traverse twice when reappearing layout effects.
// Move this into the else block of the above if statement, and modify
// reappearLayoutEffects to fire regular layout effects, too.
recursivelyTraverseLayoutEffects(
finishedRoot,
finishedWork,
committedLanes,
);
offscreenSubtreeIsHidden = prevOffscreenSubtreeIsHidden;
offscreenSubtreeWasHidden = prevOffscreenSubtreeWasHidden;
}
Expand Down Expand Up @@ -2723,90 +2698,177 @@ function recursivelyTraverseDisappearLayoutEffects(parentFiber: Fiber) {
}
}

function reappearLayoutEffects(finishedWork: Fiber) {
function reappearLayoutEffects(
finishedRoot: FiberRoot,
current: Fiber | null,
finishedWork: Fiber,
committedLanes: Lanes,
// This function visits both newly finished work and nodes that were re-used
// from a previously committed tree. We cannot check non-static flags if the
// node was reused.
includeWorkInProgressEffects: boolean,
) {
// Turn on layout effects in a tree that previously disappeared.
// TODO (Offscreen) Check: flags & LayoutStatic
const flags = finishedWork.flags;
switch (finishedWork.tag) {
case FunctionComponent:
case ForwardRef:
case SimpleMemoComponent: {
recursivelyTraverseReappearLayoutEffects(finishedWork);

// TODO: Check for LayoutStatic flag
if (
enableProfilerTimer &&
enableProfilerCommitHooks &&
finishedWork.mode & ProfileMode
) {
try {
startLayoutEffectTimer();
safelyCallCommitHookLayoutEffectListMount(
finishedWork,
finishedWork.return,
);
} finally {
recordLayoutEffectDuration(finishedWork);
}
} else {
safelyCallCommitHookLayoutEffectListMount(
finishedWork,
finishedWork.return,
);
}
recursivelyTraverseReappearLayoutEffects(
finishedRoot,
finishedWork,
committedLanes,
includeWorkInProgressEffects,
);
// TODO: Check flags & LayoutStatic
commitHookLayoutEffects(finishedWork, HookLayout);
break;
}
case ClassComponent: {
recursivelyTraverseReappearLayoutEffects(finishedWork);
recursivelyTraverseReappearLayoutEffects(
finishedRoot,
finishedWork,
committedLanes,
includeWorkInProgressEffects,
);

const instance = finishedWork.stateNode;
// TODO: Check for LayoutStatic flag
const instance = finishedWork.stateNode;
if (typeof instance.componentDidMount === 'function') {
safelyCallComponentDidMount(
finishedWork,
finishedWork.return,
instance,
);
try {
instance.componentDidMount();
} catch (error) {
captureCommitPhaseError(finishedWork, finishedWork.return, error);
}
}
// TODO: Check for RefStatic flag
safelyAttachRef(finishedWork, finishedWork.return);

// Commit any callbacks that would have fired while the component
// was hidden.
const updateQueue: UpdateQueue<
*,
> | null = (finishedWork.updateQueue: any);
if (updateQueue !== null) {
commitHiddenCallbacks(updateQueue, instance);
}

// If this is newly finished work, check for setState callbacks
if (includeWorkInProgressEffects && flags & Callback) {
commitClassCallbacks(finishedWork);
}

// TODO: Check flags & RefStatic
safelyAttachRef(finishedWork, finishedWork.return);
break;
}
// Unlike commitLayoutEffectsOnFiber, we don't need to handle HostRoot
// because this function only visits nodes that are inside an
// Offscreen fiber.
// case HostRoot: {
// ...
// }
case HostComponent: {
recursivelyTraverseReappearLayoutEffects(finishedWork);
recursivelyTraverseReappearLayoutEffects(
finishedRoot,
finishedWork,
committedLanes,
includeWorkInProgressEffects,
);

// TODO: Check for RefStatic flag
// Renderers may schedule work to be done after host components are mounted
// (eg DOM renderer may schedule auto-focus for inputs and form controls).
// These effects should only be committed when components are first mounted,
// aka when there is no current/alternate.
if (includeWorkInProgressEffects && current === null && flags & Update) {
commitHostComponentMount(finishedWork);
}

// TODO: Check flags & Ref
safelyAttachRef(finishedWork, finishedWork.return);
break;
}
case Profiler: {
recursivelyTraverseReappearLayoutEffects(
finishedRoot,
finishedWork,
committedLanes,
includeWorkInProgressEffects,
);
// TODO: Figure out how Profiler updates should work with Offscreen
if (includeWorkInProgressEffects && flags & Update) {
commitProfilerUpdate(finishedWork, current);
}
break;
}
case SuspenseComponent: {
recursivelyTraverseReappearLayoutEffects(
finishedRoot,
finishedWork,
committedLanes,
includeWorkInProgressEffects,
);

// TODO: Figure out how Suspense hydration callbacks should work
// with Offscreen.
if (includeWorkInProgressEffects && flags & Update) {
commitSuspenseHydrationCallbacks(finishedRoot, finishedWork);
}
break;
}
case OffscreenComponent: {
const isHidden = finishedWork.memoizedState !== null;
const offscreenState: OffscreenState = finishedWork.memoizedState;
const isHidden = offscreenState !== null;
if (isHidden) {
// Nested Offscreen tree is still hidden. Don't re-appear its effects.
} else {
recursivelyTraverseReappearLayoutEffects(finishedWork);
recursivelyTraverseReappearLayoutEffects(
finishedRoot,
finishedWork,
committedLanes,
includeWorkInProgressEffects,
);
}
break;
}
default: {
recursivelyTraverseReappearLayoutEffects(finishedWork);
recursivelyTraverseReappearLayoutEffects(
finishedRoot,
finishedWork,
committedLanes,
includeWorkInProgressEffects,
);
break;
}
}
}

function recursivelyTraverseReappearLayoutEffects(parentFiber: Fiber) {
function recursivelyTraverseReappearLayoutEffects(
finishedRoot: FiberRoot,
parentFiber: Fiber,
committedLanes: Lanes,
includeWorkInProgressEffects: boolean,
) {
// This function visits both newly finished work and nodes that were re-used
// from a previously committed tree. We cannot check non-static flags if the
// node was reused.
const childShouldIncludeWorkInProgressEffects =
includeWorkInProgressEffects &&
(parentFiber.subtreeFlags & LayoutMask) !== NoFlags;

// TODO (Offscreen) Check: flags & (RefStatic | LayoutStatic)
const prevDebugFiber = getCurrentDebugFiberInDEV();
let child = parentFiber.child;
while (child !== null) {
reappearLayoutEffects(child);
const current = child.alternate;
reappearLayoutEffects(
finishedRoot,
current,
child,
committedLanes,
childShouldIncludeWorkInProgressEffects,
);
child = child.sibling;
}
setCurrentDebugFiberInDEV(prevDebugFiber);
}

export function commitPassiveMountEffects(
Expand Down
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