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Improve error boundary handling for unmounted subtrees (#19542)
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A passive effect's cleanup function may throw after an unmount. Prior to this commit, such an error would be ignored. (React would not notify any error boundaries.) After this commit, React's behavior varies depending on which reconciler fork is being used.

For the old reconciler, React will call componentDidCatch for the nearest unmounted error boundary (if there is one). If there are no unmounted error boundaries, React will still swallow the error because the return pointer has been disconnected, so the normal error handling logic does not know how to traverse the tree to find the nearest still-mounted ancestor.

For the new reconciler, React will skip any unmounted boundaries and look for a still-mounted boundary. If one is found, it will call getDerivedStateFromError and/or componentDidCatch (depending on the type of boundary).

Tests have been added for both reconciler variants for now.
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Brian Vaughn authored Aug 14, 2020
1 parent 9b35dd2 commit ffb749c
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Showing 5 changed files with 400 additions and 53 deletions.
56 changes: 40 additions & 16 deletions packages/react-dom/src/events/__tests__/DOMPluginEventSystem-test.internal.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1667,16 +1667,28 @@ describe('DOMPluginEventSystem', () => {

function Test() {
React.useEffect(() => {
setClick1(buttonRef.current, targetListener1);
setClick2(buttonRef.current, targetListener2);
setClick3(buttonRef.current, targetListener3);
setClick4(buttonRef.current, targetListener4);
const clearClick1 = setClick1(
buttonRef.current,
targetListener1,
);
const clearClick2 = setClick2(
buttonRef.current,
targetListener2,
);
const clearClick3 = setClick3(
buttonRef.current,
targetListener3,
);
const clearClick4 = setClick4(
buttonRef.current,
targetListener4,
);

return () => {
setClick1();
setClick2();
setClick3();
setClick4();
clearClick1();
clearClick2();
clearClick3();
clearClick4();
};
});

Expand All @@ -1701,16 +1713,28 @@ describe('DOMPluginEventSystem', () => {

function Test2() {
React.useEffect(() => {
setClick1(buttonRef.current, targetListener1);
setClick2(buttonRef.current, targetListener2);
setClick3(buttonRef.current, targetListener3);
setClick4(buttonRef.current, targetListener4);
const clearClick1 = setClick1(
buttonRef.current,
targetListener1,
);
const clearClick2 = setClick2(
buttonRef.current,
targetListener2,
);
const clearClick3 = setClick3(
buttonRef.current,
targetListener3,
);
const clearClick4 = setClick4(
buttonRef.current,
targetListener4,
);

return () => {
setClick1();
setClick2();
setClick3();
setClick4();
clearClick1();
clearClick2();
clearClick3();
clearClick4();
};
});

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51 changes: 33 additions & 18 deletions packages/react-reconciler/src/ReactFiberCommitWork.new.js
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Original file line number Diff line number Diff line change
Expand Up @@ -173,13 +173,13 @@ function safelyCallComponentWillUnmount(current, instance) {
);
if (hasCaughtError()) {
const unmountError = clearCaughtError();
captureCommitPhaseError(current, unmountError);
captureCommitPhaseError(current, current.return, unmountError);
}
} else {
try {
callComponentWillUnmountWithTimer(current, instance);
} catch (unmountError) {
captureCommitPhaseError(current, unmountError);
captureCommitPhaseError(current, current.return, unmountError);
}
}
}
Expand All @@ -192,13 +192,13 @@ function safelyDetachRef(current: Fiber) {
invokeGuardedCallback(null, ref, null, null);
if (hasCaughtError()) {
const refError = clearCaughtError();
captureCommitPhaseError(current, refError);
captureCommitPhaseError(current, current.return, refError);
}
} else {
try {
ref(null);
} catch (refError) {
captureCommitPhaseError(current, refError);
captureCommitPhaseError(current, current.return, refError);
}
}
} else {
Expand All @@ -207,18 +207,22 @@ function safelyDetachRef(current: Fiber) {
}
}

export function safelyCallDestroy(current: Fiber, destroy: () => void) {
export function safelyCallDestroy(
current: Fiber,
nearestMountedAncestor: Fiber | null,
destroy: () => void,
) {
if (__DEV__) {
invokeGuardedCallback(null, destroy, null);
if (hasCaughtError()) {
const error = clearCaughtError();
captureCommitPhaseError(current, error);
captureCommitPhaseError(current, nearestMountedAncestor, error);
}
} else {
try {
destroy();
} catch (error) {
captureCommitPhaseError(current, error);
captureCommitPhaseError(current, nearestMountedAncestor, error);
}
}
}
Expand Down Expand Up @@ -337,10 +341,10 @@ function commitHookEffectListUnmount(tag: HookEffectTag, finishedWork: Fiber) {

// TODO: Remove this duplication.
function commitHookEffectListUnmount2(
// Tags to check for when deciding whether to unmount. e.g. to skip over
// layout effects
// Tags to check for when deciding whether to unmount. e.g. to skip over layout effects
hookEffectTag: HookEffectTag,
fiber: Fiber,
nearestMountedAncestor: Fiber | null,
): void {
const updateQueue: FunctionComponentUpdateQueue | null = (fiber.updateQueue: any);
const lastEffect = updateQueue !== null ? updateQueue.lastEffect : null;
Expand All @@ -359,10 +363,10 @@ function commitHookEffectListUnmount2(
fiber.mode & ProfileMode
) {
startPassiveEffectTimer();
safelyCallDestroy(fiber, destroy);
safelyCallDestroy(fiber, nearestMountedAncestor, destroy);
recordPassiveEffectDuration(fiber);
} else {
safelyCallDestroy(fiber, destroy);
safelyCallDestroy(fiber, nearestMountedAncestor, destroy);
}
}
}
Expand Down Expand Up @@ -465,7 +469,7 @@ function commitHookEffectListMount2(fiber: Fiber): void {
if (hasCaughtError()) {
invariant(fiber !== null, 'Should be working on an effect.');
const error = clearCaughtError();
captureCommitPhaseError(fiber, error);
captureCommitPhaseError(fiber, fiber.return, error);
}
} else {
try {
Expand All @@ -488,7 +492,7 @@ function commitHookEffectListMount2(fiber: Fiber): void {
// The warning refers to useEffect but only applies to useLayoutEffect.
} catch (error) {
invariant(fiber !== null, 'Should be working on an effect.');
captureCommitPhaseError(fiber, error);
captureCommitPhaseError(fiber, fiber.return, error);
}
}
}
Expand Down Expand Up @@ -997,10 +1001,10 @@ function commitUnmount(
current.mode & ProfileMode
) {
startLayoutEffectTimer();
safelyCallDestroy(current, destroy);
safelyCallDestroy(current, current.return, destroy);
recordLayoutEffectDuration(current);
} else {
safelyCallDestroy(current, destroy);
safelyCallDestroy(current, current.return, destroy);
}
}
}
Expand Down Expand Up @@ -1842,18 +1846,29 @@ function commitPassiveWork(finishedWork: Fiber): void {
case ForwardRef:
case SimpleMemoComponent:
case Block: {
commitHookEffectListUnmount2(HookPassive | HookHasEffect, finishedWork);
commitHookEffectListUnmount2(
HookPassive | HookHasEffect,
finishedWork,
finishedWork.return,
);
}
}
}

function commitPassiveUnmount(current: Fiber): void {
function commitPassiveUnmount(
current: Fiber,
nearestMountedAncestor: Fiber | null,
): void {
switch (current.tag) {
case FunctionComponent:
case ForwardRef:
case SimpleMemoComponent:
case Block:
commitHookEffectListUnmount2(HookPassive, current);
commitHookEffectListUnmount2(
HookPassive,
current,
nearestMountedAncestor,
);
}
}

Expand Down
34 changes: 21 additions & 13 deletions packages/react-reconciler/src/ReactFiberWorkLoop.new.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2393,14 +2393,14 @@ function commitBeforeMutationEffects(firstChild: Fiber) {
invokeGuardedCallback(null, commitBeforeMutationEffectsImpl, null, fiber);
if (hasCaughtError()) {
const error = clearCaughtError();
captureCommitPhaseError(fiber, error);
captureCommitPhaseError(fiber, fiber.return, error);
}
resetCurrentDebugFiberInDEV();
} else {
try {
commitBeforeMutationEffectsImpl(fiber);
} catch (error) {
captureCommitPhaseError(fiber, error);
captureCommitPhaseError(fiber, fiber.return, error);
}
}
fiber = fiber.sibling;
Expand Down Expand Up @@ -2490,14 +2490,14 @@ function commitMutationEffects(
);
if (hasCaughtError()) {
const error = clearCaughtError();
captureCommitPhaseError(fiber, error);
captureCommitPhaseError(fiber, fiber.return, error);
}
resetCurrentDebugFiberInDEV();
} else {
try {
commitMutationEffectsImpl(fiber, root, renderPriorityLevel);
} catch (error) {
captureCommitPhaseError(fiber, error);
captureCommitPhaseError(fiber, fiber.return, error);
}
}
fiber = fiber.sibling;
Expand Down Expand Up @@ -2593,13 +2593,13 @@ function commitMutationEffectsDeletions(
);
if (hasCaughtError()) {
const error = clearCaughtError();
captureCommitPhaseError(childToDelete, error);
captureCommitPhaseError(childToDelete, childToDelete.return, error);
}
} else {
try {
commitDeletion(root, childToDelete, renderPriorityLevel);
} catch (error) {
captureCommitPhaseError(childToDelete, error);
captureCommitPhaseError(childToDelete, childToDelete.return, error);
}
}
}
Expand Down Expand Up @@ -2641,14 +2641,14 @@ function commitLayoutEffects(
);
if (hasCaughtError()) {
const error = clearCaughtError();
captureCommitPhaseError(fiber, error);
captureCommitPhaseError(fiber, fiber.return, error);
}
resetCurrentDebugFiberInDEV();
} else {
try {
commitLayoutEffectsImpl(fiber, root, committedLanes);
} catch (error) {
captureCommitPhaseError(fiber, error);
captureCommitPhaseError(fiber, fiber.return, error);
}
}
fiber = fiber.sibling;
Expand Down Expand Up @@ -2748,7 +2748,7 @@ function flushPassiveUnmountEffects(firstChild: Fiber): void {
if (deletions !== null) {
for (let i = 0; i < deletions.length; i++) {
const fiberToDelete = deletions[i];
flushPassiveUnmountEffectsInsideOfDeletedTree(fiberToDelete);
flushPassiveUnmountEffectsInsideOfDeletedTree(fiberToDelete, fiber);

// Now that passive effects have been processed, it's safe to detach lingering pointers.
detachFiberAfterEffects(fiberToDelete);
Expand Down Expand Up @@ -2780,6 +2780,7 @@ function flushPassiveUnmountEffects(firstChild: Fiber): void {

function flushPassiveUnmountEffectsInsideOfDeletedTree(
fiberToDelete: Fiber,
nearestMountedAncestor: Fiber,
): void {
if ((fiberToDelete.subtreeTag & PassiveStaticSubtreeTag) !== NoSubtreeTag) {
// If any children have passive effects then traverse the subtree.
Expand All @@ -2788,14 +2789,17 @@ function flushPassiveUnmountEffectsInsideOfDeletedTree(
// since that would not cover passive effects in siblings.
let child = fiberToDelete.child;
while (child !== null) {
flushPassiveUnmountEffectsInsideOfDeletedTree(child);
flushPassiveUnmountEffectsInsideOfDeletedTree(
child,
nearestMountedAncestor,
);
child = child.sibling;
}
}

if ((fiberToDelete.effectTag & PassiveStatic) !== NoEffect) {
setCurrentDebugFiberInDEV(fiberToDelete);
commitPassiveUnmount(fiberToDelete);
commitPassiveUnmount(fiberToDelete, nearestMountedAncestor);
resetCurrentDebugFiberInDEV();
}
}
Expand Down Expand Up @@ -2922,15 +2926,19 @@ function captureCommitPhaseErrorOnRoot(
}
}

export function captureCommitPhaseError(sourceFiber: Fiber, error: mixed) {
export function captureCommitPhaseError(
sourceFiber: Fiber,
nearestMountedAncestor: Fiber | null,
error: mixed,
) {
if (sourceFiber.tag === HostRoot) {
// Error was thrown at the root. There is no parent, so the root
// itself should capture it.
captureCommitPhaseErrorOnRoot(sourceFiber, sourceFiber, error);
return;
}

let fiber = sourceFiber.return;
let fiber = nearestMountedAncestor;
while (fiber !== null) {
if (fiber.tag === HostRoot) {
captureCommitPhaseErrorOnRoot(fiber, sourceFiber, error);
Expand Down
18 changes: 18 additions & 0 deletions packages/react-reconciler/src/ReactFiberWorkLoop.old.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2850,6 +2850,24 @@ export function captureCommitPhaseError(sourceFiber: Fiber, error: mixed) {
markRootUpdated(root, SyncLane, eventTime);
ensureRootIsScheduled(root, eventTime);
schedulePendingInteractions(root, SyncLane);
} else {
// This component has already been unmounted.
// We can't schedule any follow up work for the root because the fiber is already unmounted,
// but we can still call the log-only boundary so the error isn't swallowed.
//
// TODO This is only a temporary bandaid for the old reconciler fork.
// We can delete this special case once the new fork is merged.
if (
typeof instance.componentDidCatch === 'function' &&
!isAlreadyFailedLegacyErrorBoundary(instance)
) {
try {
instance.componentDidCatch(error, errorInfo);
} catch (errorToIgnore) {
// TODO Ignore this error? Rethrow it?
// This is kind of an edge case.
}
}
}
return;
}
Expand Down
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