Log Suspended startViewTransition Phase

packages/react-dom-bindings/src/client/ReactFiberConfigDOM.js

@@ -125,6 +125,7 @@ import {
   enableViewTransition,
   enableHydrationChangeEvent,
   enableFragmentRefsScrollIntoView,
+  enableProfilerTimer,
 } from 'shared/ReactFeatureFlags';
 import {
   HostComponent,
@@ -2098,6 +2099,7 @@ export function startViewTransition(
   spawnedWorkCallback: () => void,
   passiveCallback: () => mixed,
   errorCallback: mixed => void,
+  blockedCallback: string => void, // Profiling-only
 ): null | RunningViewTransition {
   const ownerDocument: Document =
     rootContainer.nodeType === DOCUMENT_NODE
@@ -2131,10 +2133,10 @@ export function startViewTransition(
             blockingPromises.push(ownerDocument.fonts.ready);
           }
         }
+        const blockingIndexSnapshot = blockingPromises.length;
         if (suspendedState !== null) {
           // Suspend on any images that still haven't loaded and are in the viewport.
           const suspenseyImages = suspendedState.suspenseyImages;
-          const blockingIndexSnapshot = blockingPromises.length;
           let imgBytes = 0;
           for (let i = 0; i < suspenseyImages.length; i++) {
             const suspenseyImage = suspenseyImages[i];
@@ -2162,6 +2164,15 @@ export function startViewTransition(
           }
         }
         if (blockingPromises.length > 0) {
+          if (enableProfilerTimer) {
+            const blockedReason =
+              blockingIndexSnapshot > 0
+                ? blockingPromises.length > blockingIndexSnapshot
+                  ? 'Waiting on Fonts and Images'
+                  : 'Waiting on Fonts'
+                : 'Waiting on Images';
+            blockedCallback(blockedReason);
+          }
           const blockingReady = Promise.race([
             Promise.all(blockingPromises),
             new Promise(resolve =>

packages/react-native-renderer/src/ReactFiberConfigNative.js

@@ -673,6 +673,7 @@ export function startViewTransition(
   spawnedWorkCallback: () => void,
   passiveCallback: () => mixed,
   errorCallback: mixed => void,
+  blockedCallback: string => void, // Profiling-only
 ): null | RunningViewTransition {
   mutationCallback();
   layoutCallback();

packages/react-reconciler/src/ReactFiberPerformanceTrack.js

@@ -1254,6 +1254,45 @@ export function logSuspendedCommitPhase(
   }
 }
 
+export function logSuspendedViewTransitionPhase(
+  startTime: number,
+  endTime: number,
+  reason: string,
+  debugTask: null | ConsoleTask,
+): void {
+  // This means the commit was suspended on CSS or images.
+  if (supportsUserTiming) {
+    if (endTime <= startTime) {
+      return;
+    }
+    // TODO: Include the exact reason and URLs of what resources suspended.
+    // TODO: This might also be Suspended while waiting on a View Transition.
+    if (__DEV__ && debugTask) {
+      debugTask.run(
+        // $FlowFixMe[method-unbinding]
+        console.timeStamp.bind(
+          console,
+          reason,
+          startTime,
+          endTime,
+          currentTrack,
+          LANES_TRACK_GROUP,
+          'secondary-light',
+        ),
+      );
+    } else {
+      console.timeStamp(
+        reason,
+        startTime,
+        endTime,
+        currentTrack,
+        LANES_TRACK_GROUP,
+        'secondary-light',
+      );
+    }
+  }
+}
+
 export function logCommitErrored(
   startTime: number,
   endTime: number,

packages/react-reconciler/src/ReactFiberWorkLoop.js

@@ -81,6 +81,7 @@ import {
   logSuspendedWithDelayPhase,
   logSuspenseThrottlePhase,
   logSuspendedCommitPhase,
+  logSuspendedViewTransitionPhase,
   logCommitPhase,
   logPaintYieldPhase,
   logStartViewTransitionYieldPhase,
@@ -704,6 +705,7 @@ let pendingTransitionTypes: null | TransitionTypes = null;
 let pendingDidIncludeRenderPhaseUpdate: boolean = false;
 let pendingSuspendedCommitReason: SuspendedCommitReason = IMMEDIATE_COMMIT; // Profiling-only
 let pendingDelayedCommitReason: DelayedCommitReason = IMMEDIATE_COMMIT; // Profiling-only
+let pendingSuspendedViewTransitionReason: null | string = null; // Profiling-only
 
 // Use these to prevent an infinite loop of nested updates
 const NESTED_UPDATE_LIMIT = 50;
@@ -3445,6 +3447,7 @@ function commitRoot(
     pendingEffectsRenderEndTime = completedRenderEndTime;
     pendingSuspendedCommitReason = suspendedCommitReason;
     pendingDelayedCommitReason = IMMEDIATE_COMMIT;
+    pendingSuspendedViewTransitionReason = null;
   }
 
   if (enableGestureTransition && isGestureRender(lanes)) {
@@ -3604,6 +3607,7 @@ function commitRoot(
       flushSpawnedWork,
       flushPassiveEffects,
       reportViewTransitionError,
+      enableProfilerTimer ? suspendedViewTransition : (null: any),
     );
   } else {
     // Flush synchronously.
@@ -3624,6 +3628,24 @@ function reportViewTransitionError(error: mixed) {
   onRecoverableError(error, makeErrorInfo(null));
 }
 
+function suspendedViewTransition(reason: string): void {
+  if (enableProfilerTimer && enableComponentPerformanceTrack) {
+    // We'll split the commit into two phases, because we're suspended in the middle.
+    recordCommitEndTime();
+    logCommitPhase(
+      pendingSuspendedCommitReason === IMMEDIATE_COMMIT
+        ? pendingEffectsRenderEndTime
+        : commitStartTime,
+      commitEndTime,
+      commitErrors,
+      pendingDelayedCommitReason === ABORTED_VIEW_TRANSITION_COMMIT,
+      workInProgressUpdateTask,
+    );
+    pendingSuspendedViewTransitionReason = reason;
+    pendingSuspendedCommitReason = SUSPENDED_COMMIT;
+  }
+}
+
 function flushAfterMutationEffects(): void {
   if (pendingEffectsStatus !== PENDING_AFTER_MUTATION_PHASE) {
     return;
@@ -3688,6 +3710,21 @@ function flushLayoutEffects(): void {
   }
   pendingEffectsStatus = NO_PENDING_EFFECTS;
 
+  if (enableProfilerTimer && enableComponentPerformanceTrack) {
+    const suspendedViewTransitionReason = pendingSuspendedViewTransitionReason;
+    if (suspendedViewTransitionReason !== null) {
+      // We suspended in the middle of the commit for the view transition.
+      // We'll start a new commit track now.
+      recordCommitTime();
+      logSuspendedViewTransitionPhase(
+        commitEndTime, // The start is the end of the first commit part.
+        commitStartTime, // The end is the start of the second commit part.
+        suspendedViewTransitionReason,
+        workInProgressUpdateTask,
+      );
+    }
+  }
+
   const root = pendingEffectsRoot;
   const finishedWork = pendingFinishedWork;
   const lanes = pendingEffectsLanes;

packages/react-test-renderer/src/ReactFiberConfigTestHost.js

@@ -423,6 +423,7 @@ export function startViewTransition(
   spawnedWorkCallback: () => void,
   passiveCallback: () => mixed,
   errorCallback: mixed => void,
+  blockedCallback: string => void, // Profiling-only
 ): null | RunningViewTransition {
   mutationCallback();
   layoutCallback();