Throttle retries even if everything has loaded (#26611)

If a Suspense fallback is shown, and the data finishes loading really
quickly after that, we throttle the content from appearing for 500ms to
reduce thrash.

This already works for successive fallback states (like if one fallback
is nested inside another) but it wasn't being applied to the final step
in the sequence: if there were no more unresolved Suspense boundaries in
the tree, the content would appear immediately.

This fixes the throttling behavior so that it applies to all renders
that are the result of suspended data being loaded. (Our internal jargon
term for this is a "retry".)

DiffTrain build for [8256781](8256781)

Author: acdlite

compiled/facebook-www/REVISION

@@ -1 +1 @@
-6b90976bc10f325146b193286435a4b5015ef605
+8256781fdf3ae1947a7f27ddc78ae11b9989c2cd

compiled/facebook-www/React-dev.modern.js

@@ -27,7 +27,7 @@ if (
 }
           "use strict";
 
-var ReactVersion = "18.3.0-www-modern-54376ec8";
+var ReactVersion = "18.3.0-www-modern-ad6e07a1";
 
 // ATTENTION
 // When adding new symbols to this file,

compiled/facebook-www/ReactART-dev.classic.js

@@ -69,7 +69,7 @@ function _assertThisInitialized(self) {
   return self;
 }
 
-var ReactVersion = "18.3.0-www-classic-d940bd0e";
+var ReactVersion = "18.3.0-www-classic-3684ffc4";
 
 var LegacyRoot = 0;
 var ConcurrentRoot = 1;
@@ -24184,109 +24184,89 @@ function queueRecoverableErrors(errors) {
 }
 
 function finishConcurrentRender(root, exitStatus, finishedWork, lanes) {
+  // TODO: The fact that most of these branches are identical suggests that some
+  // of the exit statuses are not best modeled as exit statuses and should be
+  // tracked orthogonally.
   switch (exitStatus) {
     case RootInProgress:
     case RootFatalErrored: {
       throw new Error("Root did not complete. This is a bug in React.");
     }
 
-    case RootErrored: {
-      // We should have already attempted to retry this tree. If we reached
-      // this point, it errored again. Commit it.
-      commitRootWhenReady(
-        root,
-        finishedWork,
-        workInProgressRootRecoverableErrors,
-        workInProgressTransitions,
-        lanes
-      );
-      break;
-    }
-
-    case RootSuspended: {
-      markRootSuspended(root, lanes); // We have an acceptable loading state. We need to figure out if we
-      // should immediately commit it or wait a bit.
-
-      if (
-        includesOnlyRetries(lanes) && // do not delay if we're inside an act() scope
-        !shouldForceFlushFallbacksInDEV()
-      ) {
-        // This render only included retries, no updates. Throttle committing
-        // retries so that we don't show too many loading states too quickly.
-        var msUntilTimeout =
-          globalMostRecentFallbackTime + FALLBACK_THROTTLE_MS - now$1(); // Don't bother with a very short suspense time.
-
-        if (msUntilTimeout > 10) {
-          var nextLanes = getNextLanes(root, NoLanes);
-
-          if (nextLanes !== NoLanes) {
-            // There's additional work on this root.
-            break;
-          } // The render is suspended, it hasn't timed out, and there's no
-          // lower priority work to do. Instead of committing the fallback
-          // immediately, wait for more data to arrive.
-
-          root.timeoutHandle = scheduleTimeout(
-            commitRootWhenReady.bind(
-              null,
-              root,
-              finishedWork,
-              workInProgressRootRecoverableErrors,
-              workInProgressTransitions,
-              lanes
-            ),
-            msUntilTimeout
-          );
-          break;
-        }
-      } // The work expired. Commit immediately.
-
-      commitRootWhenReady(
-        root,
-        finishedWork,
-        workInProgressRootRecoverableErrors,
-        workInProgressTransitions,
-        lanes
-      );
-      break;
-    }
-
     case RootSuspendedWithDelay: {
-      markRootSuspended(root, lanes);
-
       if (includesOnlyTransitions(lanes)) {
         // This is a transition, so we should exit without committing a
         // placeholder and without scheduling a timeout. Delay indefinitely
         // until we receive more data.
-        break;
+        markRootSuspended(root, lanes);
+        return;
       } // Commit the placeholder.
 
-      commitRootWhenReady(
-        root,
-        finishedWork,
-        workInProgressRootRecoverableErrors,
-        workInProgressTransitions,
-        lanes
-      );
       break;
     }
 
+    case RootErrored:
+    case RootSuspended:
     case RootCompleted: {
-      // The work completed.
-      commitRootWhenReady(
-        root,
-        finishedWork,
-        workInProgressRootRecoverableErrors,
-        workInProgressTransitions,
-        lanes
-      );
       break;
     }
 
     default: {
       throw new Error("Unknown root exit status.");
     }
   }
+
+  if (shouldForceFlushFallbacksInDEV()) {
+    // We're inside an `act` scope. Commit immediately.
+    commitRoot(
+      root,
+      workInProgressRootRecoverableErrors,
+      workInProgressTransitions
+    );
+  } else {
+    if (includesOnlyRetries(lanes)) {
+      // This render only included retries, no updates. Throttle committing
+      // retries so that we don't show too many loading states too quickly.
+      var msUntilTimeout =
+        globalMostRecentFallbackTime + FALLBACK_THROTTLE_MS - now$1(); // Don't bother with a very short suspense time.
+
+      if (msUntilTimeout > 10) {
+        markRootSuspended(root, lanes);
+        var nextLanes = getNextLanes(root, NoLanes);
+
+        if (nextLanes !== NoLanes) {
+          // There's additional work we can do on this root. We might as well
+          // attempt to work on that while we're suspended.
+          return;
+        } // The render is suspended, it hasn't timed out, and there's no
+        // lower priority work to do. Instead of committing the fallback
+        // immediately, wait for more data to arrive.
+        // TODO: Combine retry throttling with Suspensey commits. Right now they
+        // run one after the other.
+
+        root.timeoutHandle = scheduleTimeout(
+          commitRootWhenReady.bind(
+            null,
+            root,
+            finishedWork,
+            workInProgressRootRecoverableErrors,
+            workInProgressTransitions,
+            lanes
+          ),
+          msUntilTimeout
+        );
+        return;
+      }
+    }
+
+    commitRootWhenReady(
+      root,
+      finishedWork,
+      workInProgressRootRecoverableErrors,
+      workInProgressTransitions,
+      lanes
+    );
+  }
 }
 
 function commitRootWhenReady(
@@ -24296,6 +24276,8 @@ function commitRootWhenReady(
   transitions,
   lanes
 ) {
+  // TODO: Combine retry throttling with Suspensey commits. Right now they run
+  // one after the other.
   if (includesOnlyNonUrgentLanes(lanes)) {
     // the suspensey resources. The renderer is responsible for accumulating
     // all the load events. This all happens in a single synchronous
@@ -24315,22 +24297,14 @@ function commitRootWhenReady(
       // us that it's ready. This will be canceled if we start work on the
       // root again.
       root.cancelPendingCommit = schedulePendingCommit(
-        commitRoot.bind(
-          null,
-          root,
-          workInProgressRootRecoverableErrors,
-          workInProgressTransitions
-        )
+        commitRoot.bind(null, root, recoverableErrors, transitions)
       );
+      markRootSuspended(root, lanes);
       return;
     }
   } // Otherwise, commit immediately.
 
-  commitRoot(
-    root,
-    workInProgressRootRecoverableErrors,
-    workInProgressTransitions
-  );
+  commitRoot(root, recoverableErrors, transitions);
 }
 
 function isRenderConsistentWithExternalStores(finishedWork) {