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[Flight] Patch Promise cycles and toString on Server Functions #35345

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Merged
sebmarkbage merged 1 commit into from
Dec 11, 2025
+441 −240
Merged

[Flight] Patch Promise cycles and toString on Server Functions #35345

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271 changes: 148 additions & 123 deletions packages/react-client/src/ReactFlightClient.js
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Original file line number Diff line number Diff line change
Expand Up @@ -894,6 +894,7 @@ function resolveModuleChunk<T>(
const resolvedChunk: ResolvedModuleChunk<T> = (chunk: any);
resolvedChunk.status = RESOLVED_MODULE;
resolvedChunk.value = value;
resolvedChunk.reason = null;
if (__DEV__) {
const debugInfo = getModuleDebugInfo(value);
if (debugInfo !== null) {
Expand Down Expand Up @@ -1114,6 +1115,8 @@ export function reportGlobalError(
// because we won't be getting any new data to resolve it.
if (chunk.status === PENDING) {
triggerErrorOnChunk(response, chunk, error);
} else if (chunk.status === INITIALIZED && chunk.reason !== null) {
chunk.reason.error(error);
}
});
if (__DEV__) {
Expand Down Expand Up @@ -1462,15 +1465,95 @@ function fulfillReference(
): void {
const {handler, parentObject, key, map, path} = reference;

for (let i = 1; i < path.length; i++) {
try {
for (let i = 1; i < path.length; i++) {
while (
typeof value === 'object' &&
value !== null &&
value.$$typeof === REACT_LAZY_TYPE
) {
// We never expect to see a Lazy node on this path because we encode those as
// separate models. This must mean that we have inserted an extra lazy node
// e.g. to replace a blocked element. We must instead look for it inside.
const referencedChunk: SomeChunk<any> = value._payload;
if (referencedChunk === handler.chunk) {
// This is a reference to the thing we're currently blocking. We can peak
// inside of it to get the value.
value = handler.value;
continue;
} else {
switch (referencedChunk.status) {
case RESOLVED_MODEL:
initializeModelChunk(referencedChunk);
break;
case RESOLVED_MODULE:
initializeModuleChunk(referencedChunk);
break;
}
switch (referencedChunk.status) {
case INITIALIZED: {
value = referencedChunk.value;
continue;
}
case BLOCKED: {
// It is possible that we're blocked on our own chunk if it's a cycle.
// Before adding the listener to the inner chunk, let's check if it would
// result in a cycle.
const cyclicHandler = resolveBlockedCycle(
referencedChunk,
reference,
);
if (cyclicHandler !== null) {
// This reference points back to this chunk. We can resolve the cycle by
// using the value from that handler.
value = cyclicHandler.value;
continue;
}
// Fallthrough
}
case PENDING: {
// If we're not yet initialized we need to skip what we've already drilled
// through and then wait for the next value to become available.
path.splice(0, i - 1);
// Add "listener" to our new chunk dependency.
if (referencedChunk.value === null) {
referencedChunk.value = [reference];
} else {
referencedChunk.value.push(reference);
}
if (referencedChunk.reason === null) {
referencedChunk.reason = [reference];
} else {
referencedChunk.reason.push(reference);
}
return;
}
case HALTED: {
// Do nothing. We couldn't fulfill.
// TODO: Mark downstreams as halted too.
return;
}
default: {
rejectReference(
response,
reference.handler,
referencedChunk.reason,
);
return;
}
}
}
}
value = value[path[i]];
}

while (
typeof value === 'object' &&
value !== null &&
value.$$typeof === REACT_LAZY_TYPE
) {
// We never expect to see a Lazy node on this path because we encode those as
// separate models. This must mean that we have inserted an extra lazy node
// e.g. to replace a blocked element. We must instead look for it inside.
// If what we're referencing is a Lazy it must be because we inserted one as a virtual node
// while it was blocked by other data. If it's no longer blocked, we can unwrap it.
const referencedChunk: SomeChunk<any> = value._payload;
if (referencedChunk === handler.chunk) {
// This is a reference to the thing we're currently blocking. We can peak
Expand All @@ -1491,132 +1574,57 @@ function fulfillReference(
value = referencedChunk.value;
continue;
}
case BLOCKED: {
// It is possible that we're blocked on our own chunk if it's a cycle.
// Before adding the listener to the inner chunk, let's check if it would
// result in a cycle.
const cyclicHandler = resolveBlockedCycle(
referencedChunk,
reference,
);
if (cyclicHandler !== null) {
// This reference points back to this chunk. We can resolve the cycle by
// using the value from that handler.
value = cyclicHandler.value;
continue;
}
// Fallthrough
}
case PENDING: {
// If we're not yet initialized we need to skip what we've already drilled
// through and then wait for the next value to become available.
path.splice(0, i - 1);
// Add "listener" to our new chunk dependency.
if (referencedChunk.value === null) {
referencedChunk.value = [reference];
} else {
referencedChunk.value.push(reference);
}
if (referencedChunk.reason === null) {
referencedChunk.reason = [reference];
} else {
referencedChunk.reason.push(reference);
}
return;
}
case HALTED: {
// Do nothing. We couldn't fulfill.
// TODO: Mark downstreams as halted too.
return;
}
default: {
rejectReference(
response,
reference.handler,
referencedChunk.reason,
);
return;
}
}
}
break;
}
value = value[path[i]];
}

while (
typeof value === 'object' &&
value !== null &&
value.$$typeof === REACT_LAZY_TYPE
) {
// If what we're referencing is a Lazy it must be because we inserted one as a virtual node
// while it was blocked by other data. If it's no longer blocked, we can unwrap it.
const referencedChunk: SomeChunk<any> = value._payload;
if (referencedChunk === handler.chunk) {
// This is a reference to the thing we're currently blocking. We can peak
// inside of it to get the value.
value = handler.value;
continue;
} else {
switch (referencedChunk.status) {
case RESOLVED_MODEL:
initializeModelChunk(referencedChunk);
const mappedValue = map(response, value, parentObject, key);
parentObject[key] = mappedValue;

// If this is the root object for a model reference, where `handler.value`
// is a stale `null`, the resolved value can be used directly.
if (key === '' && handler.value === null) {
handler.value = mappedValue;
}

// If the parent object is an unparsed React element tuple, we also need to
// update the props and owner of the parsed element object (i.e.
// handler.value).
if (
parentObject[0] === REACT_ELEMENT_TYPE &&
typeof handler.value === 'object' &&
handler.value !== null &&
handler.value.$$typeof === REACT_ELEMENT_TYPE
) {
const element: any = handler.value;
switch (key) {
case '3':
transferReferencedDebugInfo(handler.chunk, fulfilledChunk);
element.props = mappedValue;
break;
case '4':
// This path doesn't call transferReferencedDebugInfo because this reference is to a debug chunk.
if (__DEV__) {
element._owner = mappedValue;
}
break;
case RESOLVED_MODULE:
initializeModuleChunk(referencedChunk);
case '5':
// This path doesn't call transferReferencedDebugInfo because this reference is to a debug chunk.
if (__DEV__) {
element._debugStack = mappedValue;
}
break;
default:
transferReferencedDebugInfo(handler.chunk, fulfilledChunk);
break;
}
switch (referencedChunk.status) {
case INITIALIZED: {
value = referencedChunk.value;
continue;
}
}
}
break;
}

const mappedValue = map(response, value, parentObject, key);
parentObject[key] = mappedValue;

// If this is the root object for a model reference, where `handler.value`
// is a stale `null`, the resolved value can be used directly.
if (key === '' && handler.value === null) {
handler.value = mappedValue;
}

// If the parent object is an unparsed React element tuple, we also need to
// update the props and owner of the parsed element object (i.e.
// handler.value).
if (
parentObject[0] === REACT_ELEMENT_TYPE &&
typeof handler.value === 'object' &&
handler.value !== null &&
handler.value.$$typeof === REACT_ELEMENT_TYPE
) {
const element: any = handler.value;
switch (key) {
case '3':
transferReferencedDebugInfo(handler.chunk, fulfilledChunk);
element.props = mappedValue;
break;
case '4':
// This path doesn't call transferReferencedDebugInfo because this reference is to a debug chunk.
if (__DEV__) {
element._owner = mappedValue;
}
break;
case '5':
// This path doesn't call transferReferencedDebugInfo because this reference is to a debug chunk.
if (__DEV__) {
element._debugStack = mappedValue;
}
break;
default:
transferReferencedDebugInfo(handler.chunk, fulfilledChunk);
break;
} else if (__DEV__ && !reference.isDebug) {
transferReferencedDebugInfo(handler.chunk, fulfilledChunk);
}
} else if (__DEV__ && !reference.isDebug) {
transferReferencedDebugInfo(handler.chunk, fulfilledChunk);
} catch (error) {
rejectReference(response, reference.handler, error);
return;
}

handler.deps--;
Expand Down Expand Up @@ -1882,6 +1890,7 @@ function loadServerReference<A: Iterable<any>, T>(
const initializedChunk: InitializedChunk<T> = (chunk: any);
initializedChunk.status = INITIALIZED;
initializedChunk.value = handler.value;
initializedChunk.reason = null;
if (resolveListeners !== null) {
wakeChunk(response, resolveListeners, handler.value, initializedChunk);
} else {
Expand Down Expand Up @@ -2359,7 +2368,7 @@ function parseModelString(
// Symbol
return Symbol.for(value.slice(2));
}
case 'F': {
case 'h': {
// Server Reference
const ref = value.slice(2);
return getOutlinedModel(
Expand Down Expand Up @@ -3138,6 +3147,7 @@ function startReadableStream<T>(
streamState: StreamState,
): void {
let controller: ReadableStreamController = (null: any);
let closed = false;
const stream = new ReadableStream({
type: type,
start(c) {
Expand Down Expand Up @@ -3195,6 +3205,10 @@ function startReadableStream<T>(
}
},
close(json: UninitializedModel): void {
if (closed) {
return;
}
closed = true;
if (previousBlockedChunk === null) {
controller.close();
} else {
Expand All @@ -3205,6 +3219,10 @@ function startReadableStream<T>(
}
},
error(error: mixed): void {
if (closed) {
return;
}
closed = true;
if (previousBlockedChunk === null) {
// $FlowFixMe[incompatible-call]
controller.error(error);
Expand Down Expand Up @@ -3265,6 +3283,7 @@ function startAsyncIterable<T>(
(chunk: any);
initializedChunk.status = INITIALIZED;
initializedChunk.value = {done: false, value: value};
initializedChunk.reason = null;
if (resolveListeners !== null) {
wakeChunkIfInitialized(
response,
Expand Down Expand Up @@ -3294,6 +3313,9 @@ function startAsyncIterable<T>(
nextWriteIndex++;
},
close(value: UninitializedModel): void {
if (closed) {
return;
}
closed = true;
if (nextWriteIndex === buffer.length) {
buffer[nextWriteIndex] = createResolvedIteratorResultChunk(
Expand Down Expand Up @@ -3321,6 +3343,9 @@ function startAsyncIterable<T>(
}
},
error(error: Error): void {
if (closed) {
return;
}
closed = true;
if (nextWriteIndex === buffer.length) {
buffer[nextWriteIndex] =
Expand Down
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