old

packages/react-reconciler/src/ReactFiberWorkLoop.old.js

@@ -82,6 +82,7 @@ import {
   supportsMicrotasks,
   errorHydratingContainer,
   scheduleMicrotask,
+  requestPostPaintCallback,
 } from './ReactFiberHostConfig';
 
 import {
@@ -350,6 +351,7 @@ export function getWorkInProgressTransitions() {
 }
 
 let currentPendingTransitionCallbacks: PendingTransitionCallbacks | null = null;
+let currentEndTime: number | null = null;
 
 export function addTransitionStartCallbackToPendingTransition(
   transition: Transition,
@@ -2514,6 +2516,24 @@ function commitRootImpl(
     markCommitStopped();
   }
 
+  const prevRootTransitionCallbacks = root.transitionCallbacks;
+  if (prevRootTransitionCallbacks !== null) {
+    requestPostPaintCallback(endTime => {
+      const prevPendingTransitionCallbacks = currentPendingTransitionCallbacks;
+      if (prevPendingTransitionCallbacks !== null) {
+        scheduleCallback(IdleSchedulerPriority, () => {
+          processTransitionCallbacks(
+            prevPendingTransitionCallbacks,
+            endTime,
+            prevRootTransitionCallbacks,
+          );
+        });
+      } else {
+        currentEndTime = endTime;
+      }
+    });
+  }
+
   return null;
 }
 
@@ -2655,28 +2675,23 @@ function flushPassiveEffectsImpl() {
   if (enableTransitionTracing) {
     const prevPendingTransitionCallbacks = currentPendingTransitionCallbacks;
     const prevRootTransitionCallbacks = root.transitionCallbacks;
+    const prevEndTime = currentEndTime;
     if (
       prevPendingTransitionCallbacks !== null &&
       prevRootTransitionCallbacks !== null
     ) {
-      // TODO(luna) Refactor this code into the Host Config
-      // TODO(luna) The end time here is not necessarily accurate
-      // because passive effects could be called before paint
-      // (synchronously) or after paint (normally). We need
-      // to come up with a way to get the correct end time for both cases.
-      // One solution is in the host config, if the passive effects
-      // have not yet been run, make a call to flush the passive effects
-      // right after paint.
-      const endTime = now();
       currentPendingTransitionCallbacks = null;
-
-      scheduleCallback(IdleSchedulerPriority, () =>
-        processTransitionCallbacks(
-          prevPendingTransitionCallbacks,
-          endTime,
-          prevRootTransitionCallbacks,
-        ),
-      );
+      currentEndTime = null;
+
+      if (prevEndTime !== null) {
+        scheduleCallback(IdleSchedulerPriority, () =>
+          processTransitionCallbacks(
+            prevPendingTransitionCallbacks,
+            prevEndTime,
+            prevRootTransitionCallbacks,
+          ),
+        );
+      }
     }
   }