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[Flight/DevTools] Pass the Server Component's "key" as Part of the Re…
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…actComponentInfo (#30703)

Supports showing the key in DevTools on the Server Component that the
key was applied to. We can also use this to reconcile to preserve
instance equality when they're reordered.

One thing that's a bit weird about this is that if you provide an
explicit key on a Server Component that alone doesn't have any
semantics. It's because we pass the key down and let the nearest child
inherit the key or get prefixed by the key.

So you might see the same key as a prefix on the child of the Server
Component too which might be a bit confusing. We could remove the prefix
from children but that might also be a bit confusing if they collide.

The div in this case doesn't have a key explicitly specified. It gets it
from the Server Component parent.

<img width="1107" alt="Screenshot 2024-08-14 at 10 06 36 PM"
src="https://github.com/user-attachments/assets/cfc517cc-e737-44c3-a1be-050049267ee2">

Overall keys get a bit confusing when you apply filter. Especially since
it's so common to actually apply the key on a Host Instance. So you
often don't see the key.
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sebmarkbage authored Aug 15, 2024
1 parent c39da3e commit 19bd26b
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Showing 6 changed files with 64 additions and 27 deletions.
12 changes: 12 additions & 0 deletions packages/react-client/src/__tests__/ReactFlight-test.js
Original file line number Diff line number Diff line change
Expand Up @@ -299,6 +299,7 @@ describe('ReactFlight', () => {
{
name: 'Greeting',
env: 'Server',
key: null,
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in Object.<anonymous> (at **)'
Expand Down Expand Up @@ -337,6 +338,7 @@ describe('ReactFlight', () => {
{
name: 'Greeting',
env: 'Server',
key: null,
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in Object.<anonymous> (at **)'
Expand Down Expand Up @@ -2614,6 +2616,7 @@ describe('ReactFlight', () => {
{
name: 'ServerComponent',
env: 'Server',
key: null,
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in Object.<anonymous> (at **)'
Expand All @@ -2631,6 +2634,7 @@ describe('ReactFlight', () => {
{
name: 'ThirdPartyComponent',
env: 'third-party',
key: null,
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in Object.<anonymous> (at **)'
Expand All @@ -2645,6 +2649,7 @@ describe('ReactFlight', () => {
{
name: 'ThirdPartyLazyComponent',
env: 'third-party',
key: null,
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in myLazy (at **)\n in lazyInitializer (at **)'
Expand All @@ -2659,6 +2664,7 @@ describe('ReactFlight', () => {
{
name: 'ThirdPartyFragmentComponent',
env: 'third-party',
key: '3',
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in Object.<anonymous> (at **)'
Expand Down Expand Up @@ -2732,6 +2738,7 @@ describe('ReactFlight', () => {
{
name: 'ServerComponent',
env: 'Server',
key: null,
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in Object.<anonymous> (at **)'
Expand All @@ -2748,6 +2755,7 @@ describe('ReactFlight', () => {
{
name: 'Keyed',
env: 'Server',
key: 'keyed',
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in ServerComponent (at **)'
Expand All @@ -2763,6 +2771,7 @@ describe('ReactFlight', () => {
{
name: 'ThirdPartyAsyncIterableComponent',
env: 'third-party',
key: null,
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in Object.<anonymous> (at **)'
Expand Down Expand Up @@ -2920,6 +2929,7 @@ describe('ReactFlight', () => {
{
name: 'Component',
env: 'A',
key: null,
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in Object.<anonymous> (at **)'
Expand Down Expand Up @@ -3040,6 +3050,7 @@ describe('ReactFlight', () => {
const greetInfo = {
name: 'Greeting',
env: 'Server',
key: null,
owner: null,
stack: gate(flag => flag.enableOwnerStacks)
? ' in Object.<anonymous> (at **)'
Expand All @@ -3050,6 +3061,7 @@ describe('ReactFlight', () => {
{
name: 'Container',
env: 'Server',
key: null,
owner: greetInfo,
stack: gate(flag => flag.enableOwnerStacks)
? ' in Greeting (at **)'
Expand Down
18 changes: 8 additions & 10 deletions packages/react-devtools-shared/src/__tests__/store-test.js
Original file line number Diff line number Diff line change
Expand Up @@ -2439,7 +2439,7 @@ describe('Store', () => {
});

// @reactVersion > 18.2
it('can reorder keyed components', async () => {
it('can reorder keyed server components', async () => {
function ClientComponent({text}) {
return <div>{text}</div>;
}
Expand All @@ -2452,9 +2452,7 @@ describe('Store', () => {
name: 'ServerComponent',
env: 'Server',
owner: null,
// TODO: Ideally the debug info should include the "key" too to
// preserve the virtual identity of the server component when
// reordered. Atm only the children of it gets reparented.
key: key,
},
];
return ServerPromise;
Expand All @@ -2468,23 +2466,23 @@ describe('Store', () => {
expect(store).toMatchInlineSnapshot(`
[root]
▾ <App>
▾ <ServerComponent> [Server]
▾ <ServerComponent key="A"> [Server]
<ClientComponent key="A">
▾ <ServerComponent> [Server]
▾ <ServerComponent key="B"> [Server]
<ClientComponent key="B">
▾ <ServerComponent> [Server]
▾ <ServerComponent key="C"> [Server]
<ClientComponent key="C">
`);

await actAsync(() => render(<App initial={false} />));
expect(store).toMatchInlineSnapshot(`
[root]
▾ <App>
▾ <ServerComponent> [Server]
▾ <ServerComponent key="B"> [Server]
<ClientComponent key="B">
▾ <ServerComponent> [Server]
▾ <ServerComponent key="A"> [Server]
<ClientComponent key="A">
▾ <ServerComponent> [Server]
▾ <ServerComponent key="D"> [Server]
<ClientComponent key="D">
`);
});
Expand Down
51 changes: 36 additions & 15 deletions packages/react-devtools-shared/src/backend/fiber/renderer.js
Original file line number Diff line number Diff line change
Expand Up @@ -2220,9 +2220,12 @@ export function attach(

const isProfilingSupported = false; // TODO: Support Tree Base Duration Based on Children.

const key = null; // TODO: Track keys on ReactComponentInfo;
const env = instance.data.env;
let displayName = instance.data.name || '';
const componentInfo = instance.data;

const key =
typeof componentInfo.key === 'string' ? componentInfo.key : null;
const env = componentInfo.env;
let displayName = componentInfo.name || '';
if (typeof env === 'string') {
// We model environment as an HoC name for now.
displayName = env + '(' + displayName + ')';
Expand Down Expand Up @@ -2855,19 +2858,35 @@ export function attach(
);
}
}
const firstRemainingChild = remainingReconcilingChildren;
// TODO: Find the best matching existing child based on the key if defined.

let bestMatch = remainingReconcilingChildren;
if (componentInfo.key != null) {
// If there is a key try to find a matching key in the set.
bestMatch = remainingReconcilingChildren;
while (bestMatch !== null) {
if (
bestMatch.kind === VIRTUAL_INSTANCE &&
bestMatch.data.key === componentInfo.key
) {
break;
}
bestMatch = bestMatch.nextSibling;
}
}
if (
firstRemainingChild !== null &&
firstRemainingChild.kind === VIRTUAL_INSTANCE &&
firstRemainingChild.data.name === componentInfo.name &&
firstRemainingChild.data.env === componentInfo.env
bestMatch !== null &&
bestMatch.kind === VIRTUAL_INSTANCE &&
bestMatch.data.name === componentInfo.name &&
bestMatch.data.env === componentInfo.env &&
bestMatch.data.key === componentInfo.key
) {
// If the previous children had a virtual instance in the same slot
// with the same name, then we claim it and reuse it for this update.
// Update it with the latest entry.
firstRemainingChild.data = componentInfo;
moveChild(firstRemainingChild);
previousVirtualInstance = firstRemainingChild;
bestMatch.data = componentInfo;
moveChild(bestMatch);
previousVirtualInstance = bestMatch;
previousVirtualInstanceWasMount = false;
} else {
// Otherwise we create a new instance.
Expand Down Expand Up @@ -4321,11 +4340,13 @@ export function attach(
): InspectedElement | null {
const canViewSource = false;

const key = null; // TODO: Track keys on ReactComponentInfo;
const componentInfo = virtualInstance.data;
const key =
typeof componentInfo.key === 'string' ? componentInfo.key : null;
const props = null; // TODO: Track props on ReactComponentInfo;

const env = virtualInstance.data.env;
let displayName = virtualInstance.data.name || '';
const env = componentInfo.env;
let displayName = componentInfo.name || '';
if (typeof env === 'string') {
// We model environment as an HoC name for now.
displayName = env + '(' + displayName + ')';
Expand Down Expand Up @@ -4384,7 +4405,7 @@ export function attach(
// Does the component have legacy context attached to it.
hasLegacyContext: false,

key: key != null ? key : null,
key: key,

displayName: displayName,
type: ElementTypeVirtual,
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -307,7 +307,7 @@ describe('ReactFlightDOMEdge', () => {

const serializedContent = await readResult(stream1);

expect(serializedContent.length).toBeLessThan(410);
expect(serializedContent.length).toBeLessThan(425);
expect(timesRendered).toBeLessThan(5);

const model = await ReactServerDOMClient.createFromReadableStream(stream2, {
Expand Down Expand Up @@ -374,7 +374,7 @@ describe('ReactFlightDOMEdge', () => {
const [stream1, stream2] = passThrough(stream).tee();

const serializedContent = await readResult(stream1);
expect(serializedContent.length).toBeLessThan(__DEV__ ? 590 : 400);
expect(serializedContent.length).toBeLessThan(__DEV__ ? 605 : 400);
expect(timesRendered).toBeLessThan(5);

const model = await ReactServerDOMClient.createFromReadableStream(stream2, {
Expand Down
5 changes: 5 additions & 0 deletions packages/react-server/src/ReactFlightServer.js
Original file line number Diff line number Diff line change
Expand Up @@ -970,6 +970,7 @@ function callWithDebugContextInDEV<A, T>(
const componentDebugInfo: ReactComponentInfo = {
name: '',
env: task.environmentName,
key: null,
owner: task.debugOwner,
};
if (enableOwnerStacks) {
Expand Down Expand Up @@ -1036,6 +1037,7 @@ function renderFunctionComponent<Props>(
componentDebugInfo = ({
name: componentName,
env: componentEnv,
key: key,
owner: task.debugOwner,
}: ReactComponentInfo);
if (enableOwnerStacks) {
Expand Down Expand Up @@ -1575,6 +1577,7 @@ function renderElement(
const componentDebugInfo: ReactComponentInfo = {
name: 'Fragment',
env: (0, request.environmentName)(),
key: key,
owner: task.debugOwner,
stack:
task.debugStack === null
Expand Down Expand Up @@ -2615,6 +2618,7 @@ function renderModelDestructive(
> = {
name: (value: any).name,
env: (value: any).env,
key: (value: any).key,
owner: (value: any).owner,
};
if (enableOwnerStacks) {
Expand Down Expand Up @@ -3287,6 +3291,7 @@ function renderConsoleValue(
> = {
name: (value: any).name,
env: (value: any).env,
key: (value: any).key,
owner: (value: any).owner,
};
if (enableOwnerStacks) {
Expand Down
1 change: 1 addition & 0 deletions packages/shared/ReactTypes.js
Original file line number Diff line number Diff line change
Expand Up @@ -190,6 +190,7 @@ export type ReactStackTrace = Array<ReactCallSite>;
export type ReactComponentInfo = {
+name?: string,
+env?: string,
+key?: null | string,
+owner?: null | ReactComponentInfo,
+stack?: null | ReactStackTrace,
// Stashed Data for the Specific Execution Environment. Not part of the transport protocol
Expand Down

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