Unify RootDidNotComplete and RootSuspendedWithDelay exit path (#31547)

Also rename RootDidNotComplete to RootSuspendedAtTheShell since it
specifically means something suspended in the shell during hydration.

Author: sebmarkbage

packages/react-reconciler/src/ReactFiberWorkLoop.js

@@ -329,8 +329,8 @@ const RootFatalErrored = 1;
 const RootErrored = 2;
 const RootSuspended = 3;
 const RootSuspendedWithDelay = 4;
+const RootSuspendedAtTheShell = 6;
 const RootCompleted = 5;
-const RootDidNotComplete = 6;
 
 // Describes where we are in the React execution stack
 let executionContext: ExecutionContext = NoContext;
@@ -942,15 +942,6 @@ export function performWorkOnRoot(
         markRootSuspended(root, lanes, NoLane, didAttemptEntireTree);
       }
       break;
-    } else if (exitStatus === RootDidNotComplete) {
-      if (enableProfilerTimer && enableComponentPerformanceTrack) {
-        finalizeRender(lanes, now());
-      }
-      // The render unwound without completing the tree. This happens in special
-      // cases where need to exit the current render without producing a
-      // consistent tree or committing.
-      const didAttemptEntireTree = !workInProgressRootDidSkipSuspendedSiblings;
-      markRootSuspended(root, lanes, NoLane, didAttemptEntireTree);
     } else {
       // The render completed.
 
@@ -998,7 +989,7 @@ export function performWorkOnRoot(
             // from the beginning.
             // TODO: Refactor the exit algorithm to be less confusing. Maybe
             // more branches + recursion instead of a loop. I think the only
-            // thing that causes it to be a loop is the RootDidNotComplete
+            // thing that causes it to be a loop is the RootSuspendedAtTheShell
             // check. If that's true, then we don't need a loop/recursion
             // at all.
             continue;
@@ -1134,25 +1125,27 @@ function finishConcurrentRender(
       throw new Error('Root did not complete. This is a bug in React.');
     }
     case RootSuspendedWithDelay: {
-      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.
-        if (enableProfilerTimer && enableComponentPerformanceTrack) {
-          finalizeRender(lanes, now());
-        }
-        const didAttemptEntireTree =
-          !workInProgressRootDidSkipSuspendedSiblings;
-        markRootSuspended(
-          root,
-          lanes,
-          workInProgressDeferredLane,
-          didAttemptEntireTree,
-        );
-        return;
+      if (!includesOnlyTransitions(lanes)) {
+        // Commit the placeholder.
+        break;
       }
-      // Commit the placeholder.
-      break;
+    }
+    // Fallthrough
+    case RootSuspendedAtTheShell: {
+      // This is a transition, so we should exit without committing a
+      // placeholder and without scheduling a timeout. Delay indefinitely
+      // until we receive more data.
+      if (enableProfilerTimer && enableComponentPerformanceTrack) {
+        finalizeRender(lanes, renderEndTime);
+      }
+      const didAttemptEntireTree = !workInProgressRootDidSkipSuspendedSiblings;
+      markRootSuspended(
+        root,
+        lanes,
+        workInProgressDeferredLane,
+        didAttemptEntireTree,
+      );
+      return;
     }
     case RootErrored: {
       // This render errored. Ignore any recoverable errors because we weren't actually
@@ -2146,7 +2139,7 @@ function renderRootSync(
             // just yield and reset the stack when we re-enter the work loop,
             // like normal.
             resetWorkInProgressStack();
-            exitStatus = RootDidNotComplete;
+            exitStatus = RootSuspendedAtTheShell;
             break outer;
           }
           case SuspendedOnImmediate:
@@ -2465,7 +2458,7 @@ function renderRootConcurrent(root: FiberRoot, lanes: Lanes) {
             // Interrupt the current render so the work loop can switch to the
             // hydration lane.
             resetWorkInProgressStack();
-            workInProgressRootExitStatus = RootDidNotComplete;
+            workInProgressRootExitStatus = RootSuspendedAtTheShell;
             break outer;
           }
           default: {
@@ -2973,7 +2966,7 @@ function unwindUnitOfWork(unitOfWork: Fiber, skipSiblings: boolean): void {
   } while (incompleteWork !== null);
 
   // We've unwound all the way to the root.
-  workInProgressRootExitStatus = RootDidNotComplete;
+  workInProgressRootExitStatus = RootSuspendedAtTheShell;
   workInProgress = null;
 }