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[FORKED] Hidden trees should capture Suspense
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If something suspends inside a hidden tree, it should not affect
anything in the visible part of the UI. This means that Offscreen acts
like a Suspense boundary whenever it's in its hidden state.
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@acdlite
acdlite committed Jul 5, 2022
1 parent c1f5884 commit 67de5e3
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Showing 14 changed files with 670 additions and 121 deletions.
2 changes: 2 additions & 0 deletions packages/react-reconciler/src/ReactFiber.new.js
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Original file line number Diff line number Diff line change
Expand Up @@ -719,6 +719,7 @@ export function createFiberFromOffscreen(
const primaryChildInstance: OffscreenInstance = {
isHidden: false,
pendingMarkers: null,
retryCache: null,
transitions: null,
};
fiber.stateNode = primaryChildInstance;
Expand All @@ -740,6 +741,7 @@ export function createFiberFromLegacyHidden(
isHidden: false,
pendingMarkers: null,
transitions: null,
retryCache: null,
};
fiber.stateNode = instance;
return fiber;
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2 changes: 2 additions & 0 deletions packages/react-reconciler/src/ReactFiber.old.js
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Original file line number Diff line number Diff line change
Expand Up @@ -719,6 +719,7 @@ export function createFiberFromOffscreen(
const primaryChildInstance: OffscreenInstance = {
isHidden: false,
pendingMarkers: null,
retryCache: null,
transitions: null,
};
fiber.stateNode = primaryChildInstance;
Expand All @@ -740,6 +741,7 @@ export function createFiberFromLegacyHidden(
isHidden: false,
pendingMarkers: null,
transitions: null,
retryCache: null,
};
fiber.stateNode = instance;
return fiber;
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189 changes: 143 additions & 46 deletions packages/react-reconciler/src/ReactFiberBeginWork.new.js
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Original file line number Diff line number Diff line change
Expand Up @@ -174,6 +174,8 @@ import {
setShallowSuspenseListContext,
pushPrimaryTreeSuspenseHandler,
pushFallbackTreeSuspenseHandler,
pushOffscreenSuspenseHandler,
reuseSuspenseHandlerOnStack,
popSuspenseHandler,
} from './ReactFiberSuspenseContext.new';
import {
Expand Down Expand Up @@ -678,6 +680,52 @@ function updateOffscreenComponent(
(enableLegacyHidden && nextProps.mode === 'unstable-defer-without-hiding')
) {
// Rendering a hidden tree.

const didSuspend = (workInProgress.flags & DidCapture) !== NoFlags;
if (didSuspend) {
// Something suspended inside a hidden tree

// Include the base lanes from the last render
const nextBaseLanes =
prevState !== null
? mergeLanes(prevState.baseLanes, renderLanes)
: renderLanes;

if (current !== null) {
// Reset to the current children
let currentChild = (workInProgress.child = current.child);

// The current render suspended, but there may be other lanes with
// pending work. We can't read `childLanes` from the current Offscreen
// fiber because we reset it when it was deferred; however, we can read
// the pending lanes from the child fibers.
let currentChildLanes = NoLanes;
while (currentChild !== null) {
currentChildLanes = mergeLanes(
mergeLanes(currentChildLanes, currentChild.lanes),
currentChild.childLanes,
);
currentChild = currentChild.sibling;
}
const lanesWeJustAttempted = nextBaseLanes;
const remainingChildLanes = removeLanes(
currentChildLanes,
lanesWeJustAttempted,
);
workInProgress.childLanes = remainingChildLanes;
} else {
workInProgress.childLanes = NoLanes;
workInProgress.child = null;
}

return deferHiddenOffscreenComponent(
current,
workInProgress,
nextBaseLanes,
renderLanes,
);
}

if ((workInProgress.mode & ConcurrentMode) === NoMode) {
// In legacy sync mode, don't defer the subtree. Render it now.
// TODO: Consider how Offscreen should work with transitions in the future
Expand All @@ -694,50 +742,28 @@ function updateOffscreenComponent(
}
}
reuseHiddenContextOnStack(workInProgress);
pushOffscreenSuspenseHandler(workInProgress);
} else if (!includesSomeLane(renderLanes, (OffscreenLane: Lane))) {
// We're hidden, and we're not rendering at Offscreen. We will bail out
// and resume this tree later.
let nextBaseLanes = renderLanes;
if (prevState !== null) {
// Include the base lanes from the last render
nextBaseLanes = mergeLanes(nextBaseLanes, prevState.baseLanes);
}

// Schedule this fiber to re-render at offscreen priority. Then bailout.
// Schedule this fiber to re-render at Offscreen priority
workInProgress.lanes = workInProgress.childLanes = laneToLanes(
OffscreenLane,
);
const nextState: OffscreenState = {
baseLanes: nextBaseLanes,
// Save the cache pool so we can resume later.
cachePool: enableCache ? getOffscreenDeferredCache() : null,
};
workInProgress.memoizedState = nextState;
workInProgress.updateQueue = null;
if (enableCache) {
// push the cache pool even though we're going to bail out
// because otherwise there'd be a context mismatch
if (current !== null) {
pushTransition(workInProgress, null, null);
}
}

// We're about to bail out, but we need to push this to the stack anyway
// to avoid a push/pop misalignment.
reuseHiddenContextOnStack(workInProgress);

if (enableLazyContextPropagation && current !== null) {
// Since this tree will resume rendering in a separate render, we need
// to propagate parent contexts now so we don't lose track of which
// ones changed.
propagateParentContextChangesToDeferredTree(
current,
workInProgress,
renderLanes,
);
}
// Include the base lanes from the last render
const nextBaseLanes =
prevState !== null
? mergeLanes(prevState.baseLanes, renderLanes)
: renderLanes;

return null;
return deferHiddenOffscreenComponent(
current,
workInProgress,
nextBaseLanes,
renderLanes,
);
} else {
// This is the second render. The surrounding visible content has already
// committed. Now we resume rendering the hidden tree.
Expand All @@ -764,6 +790,7 @@ function updateOffscreenComponent(
} else {
reuseHiddenContextOnStack(workInProgress);
}
pushOffscreenSuspenseHandler(workInProgress);
}
} else {
// Rendering a visible tree.
Expand Down Expand Up @@ -791,6 +818,7 @@ function updateOffscreenComponent(

// Push the lanes that were skipped when we bailed out.
pushHiddenContext(workInProgress, prevState);
reuseSuspenseHandlerOnStack(workInProgress);

// Since we're not hidden anymore, reset the state
workInProgress.memoizedState = null;
Expand All @@ -811,13 +839,54 @@ function updateOffscreenComponent(
// We're about to bail out, but we need to push this to the stack anyway
// to avoid a push/pop misalignment.
reuseHiddenContextOnStack(workInProgress);
reuseSuspenseHandlerOnStack(workInProgress);
}
}

reconcileChildren(current, workInProgress, nextChildren, renderLanes);
return workInProgress.child;
}

function deferHiddenOffscreenComponent(
current: Fiber | null,
workInProgress: Fiber,
nextBaseLanes: Lanes,
renderLanes: Lanes,
) {
const nextState: OffscreenState = {
baseLanes: nextBaseLanes,
// Save the cache pool so we can resume later.
cachePool: enableCache ? getOffscreenDeferredCache() : null,
};
workInProgress.memoizedState = nextState;
if (enableCache) {
// push the cache pool even though we're going to bail out
// because otherwise there'd be a context mismatch
if (current !== null) {
pushTransition(workInProgress, null, null);
}
}

// We're about to bail out, but we need to push this to the stack anyway
// to avoid a push/pop misalignment.
reuseHiddenContextOnStack(workInProgress);

pushOffscreenSuspenseHandler(workInProgress);

if (enableLazyContextPropagation && current !== null) {
// Since this tree will resume rendering in a separate render, we need
// to propagate parent contexts now so we don't lose track of which
// ones changed.
propagateParentContextChangesToDeferredTree(
current,
workInProgress,
renderLanes,
);
}

return null;
}

// Note: These happen to have identical begin phases, for now. We shouldn't hold
// ourselves to this constraint, though. If the behavior diverges, we should
// fork the function.
Expand Down Expand Up @@ -2109,13 +2178,19 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
if (enableTransitionTracing) {
const currentTransitions = getPendingTransitions();
if (currentTransitions !== null) {
// If there are no transitions, we don't need to keep track of tracing markers
const parentMarkerInstances = getMarkerInstances();
const primaryChildUpdateQueue: OffscreenQueue = {
transitions: currentTransitions,
markerInstances: parentMarkerInstances,
};
primaryChildFragment.updateQueue = primaryChildUpdateQueue;
const offscreenQueue: OffscreenQueue | null = (primaryChildFragment.updateQueue: any);
if (offscreenQueue === null) {
const newOffscreenQueue: OffscreenQueue = {
transitions: currentTransitions,
markerInstances: parentMarkerInstances,
wakeables: null,
};
primaryChildFragment.updateQueue = newOffscreenQueue;
} else {
offscreenQueue.transitions = currentTransitions;
offscreenQueue.markerInstances = parentMarkerInstances;
}
}
}

Expand All @@ -2140,6 +2215,8 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
);
workInProgress.memoizedState = SUSPENDED_MARKER;

// TODO: Transition Tracing is not yet implemented for CPU Suspense.

// Since nothing actually suspended, there will nothing to ping this to
// get it started back up to attempt the next item. While in terms of
// priority this work has the same priority as this current render, it's
Expand Down Expand Up @@ -2201,11 +2278,31 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
const currentTransitions = getPendingTransitions();
if (currentTransitions !== null) {
const parentMarkerInstances = getMarkerInstances();
const primaryChildUpdateQueue: OffscreenQueue = {
transitions: currentTransitions,
markerInstances: parentMarkerInstances,
};
primaryChildFragment.updateQueue = primaryChildUpdateQueue;
const offscreenQueue: OffscreenQueue | null = (primaryChildFragment.updateQueue: any);
const currentOffscreenQueue: OffscreenQueue | null = (current.updateQueue: any);
if (offscreenQueue === null) {
const newOffscreenQueue: OffscreenQueue = {
transitions: currentTransitions,
markerInstances: parentMarkerInstances,
wakeables: null,
};
primaryChildFragment.updateQueue = newOffscreenQueue;
} else if (offscreenQueue === currentOffscreenQueue) {
// If the work-in-progress queue is the same object as current, we
// can't modify it without cloning it first.
const newOffscreenQueue: OffscreenQueue = {
transitions: currentTransitions,
markerInstances: parentMarkerInstances,
wakeables:
currentOffscreenQueue !== null
? currentOffscreenQueue.wakeables
: null,
};
primaryChildFragment.updateQueue = newOffscreenQueue;
} else {
offscreenQueue.transitions = currentTransitions;
offscreenQueue.markerInstances = parentMarkerInstances;
}
}
}
primaryChildFragment.childLanes = getRemainingWorkInPrimaryTree(
Expand Down
2 changes: 2 additions & 0 deletions packages/react-reconciler/src/ReactFiberBeginWork.old.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2130,6 +2130,7 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
const primaryChildUpdateQueue: OffscreenQueue = {
transitions: currentTransitions,
markerInstances: parentMarkerInstances,
wakeables: null,
};
primaryChildFragment.updateQueue = primaryChildUpdateQueue;
}
Expand Down Expand Up @@ -2216,6 +2217,7 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
const primaryChildUpdateQueue: OffscreenQueue = {
transitions: currentTransitions,
markerInstances: parentMarkerInstances,
wakeables: null,
};
primaryChildFragment.updateQueue = primaryChildUpdateQueue;
}
Expand Down
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