[DevTools] Support Server Components in Tree #30684

sebmarkbage · 2024-08-14T02:25:48Z

This adds VirtualInstances to the tree. Each Fiber has a list of its parent Server Components in _debugInfo. The algorithm is that when we enter a set of fibers, we actually traverse level 0 of all the _debugInfo in each fiber. Then level 1 of each _debugInfo and so on. It would be simpler if _debugInfo only contained Server Component since then we could just look at the index in the array but it actually contains other data as well which leads to multiple passes but we don't expect it to have a lot of levels before hitting a reified fiber. Finally when we hit the end a traverse the fiber itself.

This lets us match consecutive ReactComponentInfo that are all the same at the same level. This creates a single VirtualInstance for each sequence. This lets the same Server Component instance that's a parent to multiple children appear as a single Instance instead of one per Fiber.

Since a Server Component's result can be rendered in more than one place there's not a 1:1 mapping though. If it is in different parents or if the sequence is interrupted, then it gets split into two different instances with the same ReactComponentInfo data.

The real interesting case is what happens during updates because this algorithm means that a Fiber can become reparented during an update to end up in a different VirtualInstance. The ideal would maybe be that the frontend could deal with this reparenting but instead I basically just unmount the previous instance (and its children) and mount a new instance which leads to some interesting scenarios. This is inline with the strategy I was intending to pursue anyway where instances are reconciled against the previous children of the same parent instead of the fiberToFiberInstance map - which would let us get rid of that map. In that case the model is resilient to Fiber being in more than one place at a time.

However this unmount/remount does mean that we can lose selection when this happens. We could maybe do something like using the tracked path like I did for component filters. Ideally it's a weird edge case though because you'd typically not have it. The main case that it happens now is for reorders of list of server components. In that case basically all the children move between server components while the server components themselves stay in place. We should really include the key in server components so that we can reconcile them using the key to handle reorders which would solve the common case anyway.

I convert the name to the Env(Name) pattern which allows the Environment Name to be used as a badge.

(Screenshot is with #30667. I haven't tried it with the alternative fix.)

Since the same instance can have multiple child fibers, we need a ref count to know when it's safe to delete.

When a fiber moves from one virtual parent to another, we unmount the previous one and mount a new FiberInstance. This means that it is now possible for a Fiber to be associated with more than one FiberInstance at least temporarily. It also means we can't assume that just because an instance has an alternate that we have already mounted it because it might have been deleted and recreated. This makes more sense if we reconciled from the previous parent instance than the fiberToFiberInstance map.

vercel · 2024-08-14T02:25:52Z

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hoxyq · 2024-08-14T13:07:13Z

packages/react-devtools-shared/src/backend/fiber/renderer.js

@@ -1423,10 +1442,14 @@ export function attach(
      }
    }

-    fiberToFiberInstanceMap.delete(fiber);
+    if (fiberToFiberInstanceMap.get(fiber) === fiberInstance) {


What is the possible case when fiberToFiberInstanceMap.get(fiber) !== fiberInstance? Reparenting case?

Reparenting can happen in different sequences.

E.g. if it moves to later then it can get removed first and then added. In that case we end up with the situation where we have an alternate but is actually a mount.

If it moves to earlier then it gets added first and then later removed. In this case we steal/claim the fiberToFiberInstanceMap slot for this Fiber using the newly mounted instance. Later the previous instance gets removed which shouldn't delete the newly mounted instance from this map.

hoxyq · 2024-08-14T13:10:31Z

packages/react-devtools-shared/src/backend/fiber/renderer.js

+    if (alternate !== null && fiberToFiberInstanceMap.has(alternate)) {
+      fiberToFiberInstanceMap.set(alternate, fiberInstance);
+    }


Is it possible that alternate was not registered in fiberToFiberInstanceMap before?

In the case where the initial set is flushed such as when we connect to an existing tree, we only register the mounted fibers. Not the alternates so it's possible for alternates to not be registered at any given point.

In the case where we reparent - moving to an earlier point - we insert a new FiberInstance before removing the old one.

In that case we use this pass to override the previous fiber->instance mapping with our new instance.

I'm not sure if we actually need to set the alternate to the new fiber in this case though. We could maybe actually just delete it.

packages/react-devtools-shared/src/backend/fiber/renderer.js

Co-authored-by: Ruslan Lesiutin <rdlesyutin@gmail.com>

Full list of changes: * refactor: data source for errors and warnings tracking is now in Store ([hoxyq](https://github.com/hoxyq) in [#31010](#31010)) * fix: consider alternate as a key for componentLogsEntry when inspecting raw fiber instance ([hoxyq](https://github.com/hoxyq) in [#31009](#31009)) * Fix: profiling crashes #30661 #28838 ([EdmondChuiHW](https://github.com/EdmondChuiHW) in [#31024](#31024)) * chore: remove using local storage for persisting console settings on the frontend ([hoxyq](https://github.com/hoxyq) in [#31002](#31002)) * feat: display message if user ended up opening hook script ([hoxyq](https://github.com/hoxyq) in [#31000](#31000)) * feat: expose installHook with settings argument from react-devtools-core/backend ([hoxyq](https://github.com/hoxyq) in [#30987](#30987)) * chore: remove settings manager from react-devtools-core ([hoxyq](https://github.com/hoxyq) in [#30986](#30986)) * feat[react-devtools/extension]: use chrome.storage to persist settings across sessions ([hoxyq](https://github.com/hoxyq) in [#30636](#30636)) * refactor[react-devtools]: propagate settings from global hook object to frontend ([hoxyq](https://github.com/hoxyq) in [#30610](#30610)) * chore[react-devtools]: extract some utils into separate modules to unify implementations ([hoxyq](https://github.com/hoxyq) in [#30597](#30597)) * refactor[react-devtools]: move console patching to global hook ([hoxyq](https://github.com/hoxyq) in [#30596](#30596)) * refactor[react-devtools]: remove browserTheme from ConsolePatchSettings ([hoxyq](https://github.com/hoxyq) in [#30566](#30566)) * feat[react-devtools]: add settings to global hook object ([hoxyq](https://github.com/hoxyq) in [#30564](#30564)) * fix: add Error prefix to Error objects names ([hoxyq](https://github.com/hoxyq) in [#30969](#30969)) * Add enableComponentPerformanceTrack Flag ([sebmarkbage](https://github.com/sebmarkbage) in [#30960](#30960)) * fix[rdt/fiber/renderer.js]: getCurrentFiber can be injected as null ([hoxyq](https://github.com/hoxyq) in [#30968](#30968)) * disable `enableSiblingPrerendering` in experimental channel ([gnoff](https://github.com/gnoff) in [#30952](#30952)) * refactor[react-devtools]: initialize renderer interface early ([hoxyq](https://github.com/hoxyq) in [#30946](#30946)) * Start prerendering Suspense retries immediately ([acdlite](https://github.com/acdlite) in [#30934](#30934)) * refactor[Agent/Store]: Store to send messages only after Agent is initialized ([hoxyq](https://github.com/hoxyq) in [#30945](#30945)) * refactor[RendererInterface]: expose onErrorOrWarning and getComponentStack ([hoxyq](https://github.com/hoxyq) in [#30931](#30931)) * Implement getComponentStack and onErrorOrWarning for replayed Flight logs ([sebmarkbage](https://github.com/sebmarkbage) in [#30930](#30930)) * Use Unicode Atom Symbol instead of Atom Emoji ([sebmarkbage](https://github.com/sebmarkbage) in [#30832](#30832)) * Improve Layering Between Console and Renderer ([sebmarkbage](https://github.com/sebmarkbage) in [#30925](#30925)) * Add Map for Server Component Logs ([sebmarkbage](https://github.com/sebmarkbage) in [#30905](#30905)) * Delete fiberToFiberInstanceMap ([sebmarkbage](https://github.com/sebmarkbage) in [#30900](#30900)) * Add Flight Renderer ([sebmarkbage](https://github.com/sebmarkbage) in [#30906](#30906)) * Refactor Error / Warning Count Tracking ([sebmarkbage](https://github.com/sebmarkbage) in [#30899](#30899)) * [flow] Upgrade Flow to 0.245.2 ([SamChou19815](https://github.com/SamChou19815) in [#30919](#30919)) * Separate RDT Fusebox into single-panel entry points ([huntie](https://github.com/huntie) in [#30708](#30708)) * Build Updater List from the Commit instead of Map ([sebmarkbage](https://github.com/sebmarkbage) in [#30897](#30897)) * Simplify Context Change Tracking in Profiler ([sebmarkbage](https://github.com/sebmarkbage) in [#30896](#30896)) * Remove use of .alternate in root and recordProfilingDurations ([sebmarkbage](https://github.com/sebmarkbage) in [#30895](#30895)) * Handle reordered contexts in Profiler ([sebmarkbage](https://github.com/sebmarkbage) in [#30887](#30887)) * Refactor Forcing Fallback / Error of Suspense / Error Boundaries ([sebmarkbage](https://github.com/sebmarkbage) in [#30870](#30870)) * Avoid getFiberIDUnsafe in debug() Helper ([sebmarkbage](https://github.com/sebmarkbage) in [#30878](#30878)) * Include some Filtered Fiber Instances ([sebmarkbage](https://github.com/sebmarkbage) in [#30865](#30865)) * Track root instances in a root Map ([sebmarkbage](https://github.com/sebmarkbage) in [#30875](#30875)) * Track all public HostInstances in a Map ([sebmarkbage](https://github.com/sebmarkbage) in [#30831](#30831)) * Support VirtualInstances in findAllCurrentHostInstances ([sebmarkbage](https://github.com/sebmarkbage) in [#30853](#30853)) * Add Filtering of Environment Names ([sebmarkbage](https://github.com/sebmarkbage) in [#30850](#30850)) * Support secondary environment name when it changes ([sebmarkbage](https://github.com/sebmarkbage) in [#30842](#30842)) * Increase max payload for websocket in standalone app ([runeb](https://github.com/runeb) in [#30848](#30848)) * Filter Server Components ([sebmarkbage](https://github.com/sebmarkbage) in [#30839](#30839)) * Track virtual instances on the tracked path for selections ([sebmarkbage](https://github.com/sebmarkbage) in [#30802](#30802)) * Remove displayName from inspected data ([sebmarkbage](https://github.com/sebmarkbage) in [#30841](#30841)) * chore[react-devtools/hook]: remove unused native values ([hoxyq](https://github.com/hoxyq) in [#30827](#30827)) * chore[react-devtools/extensions]: remove unused storage permission ([hoxyq](https://github.com/hoxyq) in [#30826](#30826)) * fix[react-devtools/extensions]: fixed tabs API calls and displaying restricted access popup ([hoxyq](https://github.com/hoxyq) in [#30825](#30825)) * feat[react-devtools]: support Manifest v3 for Firefox extension ([hoxyq](https://github.com/hoxyq) in [#30824](#30824)) * Reconcile Fibers Against Previous Children Instances ([sebmarkbage](https://github.com/sebmarkbage) in [#30822](#30822)) * Remove findCurrentFiberUsingSlowPathByFiberInstance ([sebmarkbage](https://github.com/sebmarkbage) in [#30818](#30818)) * Track Tree Base Duration of Virtual Instances ([sebmarkbage](https://github.com/sebmarkbage) in [#30817](#30817)) * Use Owner Stacks to Implement View Source of a Server Component ([sebmarkbage](https://github.com/sebmarkbage) in [#30798](#30798)) * Make function inspection instant ([sebmarkbage](https://github.com/sebmarkbage) in [#30786](#30786)) * Make Functions Clickable to Jump to Definition ([sebmarkbage](https://github.com/sebmarkbage) in [#30769](#30769)) * Support REACT_LEGACY_ELEMENT_TYPE for formatting JSX ([sebmarkbage](https://github.com/sebmarkbage) in [#30779](#30779)) * Find owners from the parent path that matches the Fiber or ReactComponentInfo ([sebmarkbage](https://github.com/sebmarkbage) in [#30717](#30717)) * [Flight/DevTools] Pass the Server Component's "key" as Part of the ReactComponentInfo ([sebmarkbage](https://github.com/sebmarkbage) in [#30703](#30703)) * Hide props section if it is null ([sebmarkbage](https://github.com/sebmarkbage) in [#30696](#30696)) * Support Server Components in Tree ([sebmarkbage](https://github.com/sebmarkbage) in [#30684](#30684)) * fix[react-devtools/InspectedElement]: fixed border stylings when some of the panels are not rendered ([hoxyq](https://github.com/hoxyq) in [#30676](#30676)) * Compute new reordered child set from the instance tree ([sebmarkbage](https://github.com/sebmarkbage) in [#30668](#30668)) * Unmount instance by walking the instance tree instead of the fiber tree ([sebmarkbage](https://github.com/sebmarkbage) in [#30665](#30665)) * Further Refactoring of Unmounts ([sebmarkbage](https://github.com/sebmarkbage) in [#30658](#30658)) * Remove lodash.throttle ([sebmarkbage](https://github.com/sebmarkbage) in [#30657](#30657)) * Unmount by walking previous nodes no longer in the new tree ([sebmarkbage](https://github.com/sebmarkbage) in [#30644](#30644)) * Build up DevTools Instance Shadow Tree ([sebmarkbage](https://github.com/sebmarkbage) in [#30625](#30625)) * chore[packages/react-devtools]: remove unused index.js ([hoxyq](https://github.com/hoxyq) in [#30579](#30579)) * Track DOM nodes to Fiber map for HostHoistable Resources ([sebmarkbage](https://github.com/sebmarkbage) in [#30590](#30590)) * Rename mountFiberRecursively/updateFiberRecursively ([sebmarkbage](https://github.com/sebmarkbage) in [#30586](#30586)) * Allow Highlighting/Inspect HostSingletons/Hoistables and Resources ([sebmarkbage](https://github.com/sebmarkbage) in [#30584](#30584)) * chore[react-devtools]: add global for native and use it to fork backend implementation ([hoxyq](https://github.com/hoxyq) in [#30533](#30533)) * Enable pointEvents while scrolling ([sebmarkbage](https://github.com/sebmarkbage) in [#30560](#30560)) * Make Element Inspection Feel Snappy ([sebmarkbage](https://github.com/sebmarkbage) in [#30555](#30555)) * Track the parent DevToolsInstance while mounting a tree ([sebmarkbage](https://github.com/sebmarkbage) in [#30542](#30542)) * Add DevToolsInstance to Store Stateful Information ([sebmarkbage](https://github.com/sebmarkbage) in [#30517](#30517)) * Implement "best renderer" by taking the inner most matched node ([sebmarkbage](https://github.com/sebmarkbage) in [#30494](#30494)) * Rename NativeElement to HostInstance in the Bridge ([sebmarkbage](https://github.com/sebmarkbage) in [#30491](#30491)) * Rename Fiber to Element in the Bridge Protocol and RendererInterface ([sebmarkbage](https://github.com/sebmarkbage) in [#30490](#30490)) * Stop filtering owner stacks ([sebmarkbage](https://github.com/sebmarkbage) in [#30438](#30438)) * [Fiber] Call life-cycles with a react-stack-bottom-frame stack frame ([sebmarkbage](https://github.com/sebmarkbage) in [#30429](#30429)) * [Flight] Prefix owner stacks added to the console.log with the current stack ([sebmarkbage](https://github.com/sebmarkbage) in [#30427](#30427)) * [BE] switch to hermes parser for prettier ([kassens](https://github.com/kassens) in [#30421](#30421)) * Implement Owner Stacks ([sebmarkbage](https://github.com/sebmarkbage) in [#30417](#30417)) * [BE] upgrade prettier to 3.3.3 ([kassens](https://github.com/kassens) in [#30420](#30420)) * [ci] Add yarn_test_build job to gh actions * [Fizz] Refactor Component Stack Nodes ([sebmarkbage](https://github.com/sebmarkbage) in [#30298](#30298)) * Print component stacks as error objects to get source mapping ([sebmarkbage](https://github.com/sebmarkbage) in [#30289](#30289)) * Upgrade flow to 0.235.0 ([kassens](https://github.com/kassens) in [#30118](#30118)) * fix: path handling in react devtools ([Jack-Works](https://github.com/Jack-Works) in [#29199](#29199))

sebmarkbage added 7 commits August 13, 2024 22:08

Mount virtual instances

a99a5f5

Unmount virtual instances

5402eee

Since the same instance can have multiple child fibers, we need a ref count to know when it's safe to delete.

Update virtual instances

9356b03

Badge Server Components with their environment name

31ae174

Implement Element inspection for virtual instances

082418e

Test tree

4d1de50

sebmarkbage requested a review from hoxyq August 14, 2024 02:25

facebook-github-bot added CLA Signed React Core Team Opened by a member of the React Core Team labels Aug 14, 2024

vercel bot deployed to Preview August 14, 2024 02:28 View deployment

sebmarkbage requested a review from eps1lon August 14, 2024 02:35

hoxyq approved these changes Aug 14, 2024

View reviewed changes

Update copypasta error message.

f4e101b

Co-authored-by: Ruslan Lesiutin <rdlesyutin@gmail.com>

sebmarkbage merged commit 49496d4 into facebook:main Aug 14, 2024
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eps1lon mentioned this pull request Aug 14, 2024

Update React from 187dd6a7-20240806 to 49496d49-20240814 vercel/next.js#68898

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jimkyndemeyer mentioned this pull request Aug 27, 2024

[DevTools Feature Request]: Full support for RSC server elements (component tree, props, inspect) #27758

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hoxyq mentioned this pull request Sep 25, 2024

React DevTools 5.3.1 -> 6.0.0 #31058

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[DevTools] Support Server Components in Tree #30684

[DevTools] Support Server Components in Tree #30684

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[DevTools] Support Server Components in Tree #30684

[DevTools] Support Server Components in Tree #30684

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