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[Flight/Fizz] Reset ThenableState Only in Branches Where It's Added (#…
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…28068)

Before, we used to reset the thenable state and extract the previous
state very early so that it's only the retried task that can possibly
consume it. This is nice because we can't accidentally consume that
state for any other node.

However, it does add a lot of branches of code that has to pass this
around. It also adds extra bytes on the stack per node. Even though it's
mostly just null.

This changes it so that where ever we can create a thenable state (e.g.
entering a component with hooks) we first extract this from the task.
The principle is that whatever could've created the thenable state in
the first place, must always be rerendered so it'll take the same code
paths to get there and so we'll always consume it.
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@sebmarkbage
sebmarkbage authored Jan 26, 2024
1 parent c7e735f commit 382190c
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Showing 2 changed files with 48 additions and 155 deletions.
144 changes: 29 additions & 115 deletions packages/react-server/src/ReactFizzServer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1294,11 +1294,15 @@ function renderWithHooks<Props, SecondArg>(
request: Request,
task: Task,
keyPath: KeyNode,
prevThenableState: ThenableState | null,
Component: (p: Props, arg: SecondArg) => any,
props: Props,
secondArg: SecondArg,
): any {
// Reset the task's thenable state before continuing, so that if a later
// component suspends we can reuse the same task object. If the same
// component suspends again, the thenable state will be restored.
const prevThenableState = task.thenableState;
task.thenableState = null;
const componentIdentity = {};
prepareToUseHooks(
request,
Expand Down Expand Up @@ -1345,15 +1349,15 @@ function finishClassComponent(
childContextTypes,
);
task.legacyContext = mergedContext;
renderNodeDestructive(request, task, null, nextChildren, -1);
renderNodeDestructive(request, task, nextChildren, -1);
task.legacyContext = previousContext;
return;
}
}

const prevKeyPath = task.keyPath;
task.keyPath = keyPath;
renderNodeDestructive(request, task, null, nextChildren, -1);
renderNodeDestructive(request, task, nextChildren, -1);
task.keyPath = prevKeyPath;
}

Expand Down Expand Up @@ -1391,7 +1395,6 @@ function renderIndeterminateComponent(
request: Request,
task: Task,
keyPath: KeyNode,
prevThenableState: ThenableState | null,
Component: any,
props: any,
): void {
Expand Down Expand Up @@ -1425,7 +1428,6 @@ function renderIndeterminateComponent(
request,
task,
keyPath,
prevThenableState,
Component,
props,
legacyContext,
Expand Down Expand Up @@ -1569,7 +1571,7 @@ function finishFunctionComponent(
// We're now successfully past this task, and we haven't modified the
// context stack. We don't have to pop back to the previous task every
// again, so we can use the destructive recursive form.
renderNodeDestructive(request, task, null, children, -1);
renderNodeDestructive(request, task, children, -1);
}
task.keyPath = prevKeyPath;
}
Expand Down Expand Up @@ -1646,7 +1648,6 @@ function renderForwardRef(
request: Request,
task: Task,
keyPath: KeyNode,
prevThenableState: null | ThenableState,
type: any,
props: Object,
ref: any,
Expand All @@ -1657,7 +1658,6 @@ function renderForwardRef(
request,
task,
keyPath,
prevThenableState,
type.render,
props,
ref,
Expand All @@ -1681,22 +1681,13 @@ function renderMemo(
request: Request,
task: Task,
keyPath: KeyNode,
prevThenableState: ThenableState | null,
type: any,
props: Object,
ref: any,
): void {
const innerType = type.type;
const resolvedProps = resolveDefaultProps(innerType, props);
renderElement(
request,
task,
keyPath,
prevThenableState,
innerType,
resolvedProps,
ref,
);
renderElement(request, task, keyPath, innerType, resolvedProps, ref);
}

function renderContextConsumer(
Expand Down Expand Up @@ -1749,7 +1740,7 @@ function renderContextConsumer(

const prevKeyPath = task.keyPath;
task.keyPath = keyPath;
renderNodeDestructive(request, task, null, newChildren, -1);
renderNodeDestructive(request, task, newChildren, -1);
task.keyPath = prevKeyPath;
}

Expand All @@ -1770,7 +1761,7 @@ function renderContextProvider(
const prevKeyPath = task.keyPath;
task.context = pushProvider(context, value);
task.keyPath = keyPath;
renderNodeDestructive(request, task, null, children, -1);
renderNodeDestructive(request, task, children, -1);
task.context = popProvider(context);
task.keyPath = prevKeyPath;
if (__DEV__) {
Expand All @@ -1786,7 +1777,6 @@ function renderLazyComponent(
request: Request,
task: Task,
keyPath: KeyNode,
prevThenableState: ThenableState | null,
lazyComponent: LazyComponentType<any, any>,
props: Object,
ref: any,
Expand All @@ -1797,15 +1787,7 @@ function renderLazyComponent(
const init = lazyComponent._init;
const Component = init(payload);
const resolvedProps = resolveDefaultProps(Component, props);
renderElement(
request,
task,
keyPath,
prevThenableState,
Component,
resolvedProps,
ref,
);
renderElement(request, task, keyPath, Component, resolvedProps, ref);
task.componentStack = previousComponentStack;
}

Expand All @@ -1824,7 +1806,7 @@ function renderOffscreen(
// pure indirection.
const prevKeyPath = task.keyPath;
task.keyPath = keyPath;
renderNodeDestructive(request, task, null, props.children, -1);
renderNodeDestructive(request, task, props.children, -1);
task.keyPath = prevKeyPath;
}
}
Expand All @@ -1833,7 +1815,6 @@ function renderElement(
request: Request,
task: Task,
keyPath: KeyNode,
prevThenableState: ThenableState | null,
type: any,
props: Object,
ref: any,
Expand All @@ -1843,14 +1824,7 @@ function renderElement(
renderClassComponent(request, task, keyPath, type, props);
return;
} else {
renderIndeterminateComponent(
request,
task,
keyPath,
prevThenableState,
type,
props,
);
renderIndeterminateComponent(request, task, keyPath, type, props);
return;
}
}
Expand All @@ -1876,7 +1850,7 @@ function renderElement(
case REACT_FRAGMENT_TYPE: {
const prevKeyPath = task.keyPath;
task.keyPath = keyPath;
renderNodeDestructive(request, task, null, props.children, -1);
renderNodeDestructive(request, task, props.children, -1);
task.keyPath = prevKeyPath;
return;
}
Expand All @@ -1890,7 +1864,7 @@ function renderElement(
// TODO: SuspenseList should control the boundaries.
const prevKeyPath = task.keyPath;
task.keyPath = keyPath;
renderNodeDestructive(request, task, null, props.children, -1);
renderNodeDestructive(request, task, props.children, -1);
task.keyPath = prevKeyPath;
task.componentStack = preiousComponentStack;
return;
Expand All @@ -1899,7 +1873,7 @@ function renderElement(
if (enableScopeAPI) {
const prevKeyPath = task.keyPath;
task.keyPath = keyPath;
renderNodeDestructive(request, task, null, props.children, -1);
renderNodeDestructive(request, task, props.children, -1);
task.keyPath = prevKeyPath;
return;
}
Expand All @@ -1921,19 +1895,11 @@ function renderElement(
if (typeof type === 'object' && type !== null) {
switch (type.$$typeof) {
case REACT_FORWARD_REF_TYPE: {
renderForwardRef(
request,
task,
keyPath,
prevThenableState,
type,
props,
ref,
);
renderForwardRef(request, task, keyPath, type, props, ref);
return;
}
case REACT_MEMO_TYPE: {
renderMemo(request, task, keyPath, prevThenableState, type, props, ref);
renderMemo(request, task, keyPath, type, props, ref);
return;
}
case REACT_PROVIDER_TYPE: {
Expand All @@ -1945,14 +1911,7 @@ function renderElement(
return;
}
case REACT_LAZY_TYPE: {
renderLazyComponent(
request,
task,
keyPath,
prevThenableState,
type,
props,
);
renderLazyComponent(request, task, keyPath, type, props);
return;
}
}
Expand Down Expand Up @@ -2025,7 +1984,6 @@ function replayElement(
request: Request,
task: ReplayTask,
keyPath: KeyNode,
prevThenableState: ThenableState | null,
name: null | string,
keyOrIndex: number | string,
childIndex: number,
Expand Down Expand Up @@ -2060,15 +2018,7 @@ function replayElement(
const currentNode = task.node;
task.replay = {nodes: childNodes, slots: childSlots, pendingTasks: 1};
try {
renderElement(
request,
task,
keyPath,
prevThenableState,
type,
props,
ref,
);
renderElement(request, task, keyPath, type, props, ref);
if (
task.replay.pendingTasks === 1 &&
task.replay.nodes.length > 0
Expand Down Expand Up @@ -2184,9 +2134,6 @@ function validateIterable(iterable, iteratorFn: Function): void {
function renderNodeDestructive(
request: Request,
task: Task,
// The thenable state reused from the previous attempt, if any. This is almost
// always null, except when called by retryTask.
prevThenableState: ThenableState | null,
node: ReactNodeList,
childIndex: number,
): void {
Expand Down Expand Up @@ -2223,7 +2170,6 @@ function renderNodeDestructive(
request,
task,
keyPath,
prevThenableState,
name,
keyOrIndex,
childIndex,
Expand All @@ -2236,15 +2182,7 @@ function renderNodeDestructive(
// prelude and skip it during the replay.
} else {
// We're doing a plain render.
renderElement(
request,
task,
keyPath,
prevThenableState,
type,
props,
ref,
);
renderElement(request, task, keyPath, type, props, ref);
}
return;
}
Expand All @@ -2266,7 +2204,7 @@ function renderNodeDestructive(
task.componentStack = previousComponentStack;

// Now we render the resolved node
renderNodeDestructive(request, task, null, resolvedNode, childIndex);
renderNodeDestructive(request, task, resolvedNode, childIndex);
return;
}
}
Expand Down Expand Up @@ -2314,11 +2252,12 @@ function renderNodeDestructive(
// e.g. Usable<Usable<Usable<T>>> should resolve to T
const maybeUsable: Object = node;
if (typeof maybeUsable.then === 'function') {
// Clear any previous thenable state that was created by the unwrapping.
task.thenableState = null;
const thenable: Thenable<ReactNodeList> = (maybeUsable: any);
return renderNodeDestructive(
request,
task,
null,
unwrapThenable(thenable),
childIndex,
);
Expand All @@ -2332,7 +2271,6 @@ function renderNodeDestructive(
return renderNodeDestructive(
request,
task,
null,
readContext(context),
childIndex,
);
Expand Down Expand Up @@ -2827,7 +2765,7 @@ function renderNode(
if (segment === null) {
// Replay
try {
return renderNodeDestructive(request, task, null, node, childIndex);
return renderNodeDestructive(request, task, node, childIndex);
} catch (thrownValue) {
resetHooksState();

Expand Down Expand Up @@ -2875,7 +2813,7 @@ function renderNode(
const childrenLength = segment.children.length;
const chunkLength = segment.chunks.length;
try {
return renderNodeDestructive(request, task, null, node, childIndex);
return renderNodeDestructive(request, task, node, childIndex);
} catch (thrownValue) {
resetHooksState();

Expand Down Expand Up @@ -3456,19 +3394,7 @@ function retryRenderTask(
// We call the destructive form that mutates this task. That way if something
// suspends again, we can reuse the same task instead of spawning a new one.

// Reset the task's thenable state before continuing, so that if a later
// component suspends we can reuse the same task object. If the same
// component suspends again, the thenable state will be restored.
const prevThenableState = task.thenableState;
task.thenableState = null;

renderNodeDestructive(
request,
task,
prevThenableState,
task.node,
task.childIndex,
);
renderNodeDestructive(request, task, task.node, task.childIndex);
pushSegmentFinale(
segment.chunks,
request.renderState,
Expand Down Expand Up @@ -3559,19 +3485,7 @@ function retryReplayTask(request: Request, task: ReplayTask): void {
// We call the destructive form that mutates this task. That way if something
// suspends again, we can reuse the same task instead of spawning a new one.

// Reset the task's thenable state before continuing, so that if a later
// component suspends we can reuse the same task object. If the same
// component suspends again, the thenable state will be restored.
const prevThenableState = task.thenableState;
task.thenableState = null;

renderNodeDestructive(
request,
task,
prevThenableState,
task.node,
task.childIndex,
);
renderNodeDestructive(request, task, task.node, task.childIndex);

if (task.replay.pendingTasks === 1 && task.replay.nodes.length > 0) {
throw new Error(
Expand Down
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