Extract trackPostponedBoundary boundary

Author: sebmarkbage

packages/react-server/src/ReactFizzServer.js

@@ -3774,6 +3774,49 @@ function renderChildrenArray(
   }
 }
 
+function trackPostponedBoundary(
+  request: Request,
+  trackedPostpones: PostponedHoles,
+  boundary: SuspenseBoundary,
+): ReplaySuspenseBoundary {
+  boundary.status = POSTPONED;
+  // We need to eagerly assign it an ID because we'll need to refer to
+  // it before flushing and we know that we can't inline it.
+  boundary.rootSegmentID = request.nextSegmentId++;
+
+  const boundaryKeyPath = boundary.trackedContentKeyPath;
+  if (boundaryKeyPath === null) {
+    throw new Error(
+      'It should not be possible to postpone at the root. This is a bug in React.',
+    );
+  }
+
+  const fallbackReplayNode = boundary.trackedFallbackNode;
+
+  const children: Array<ReplayNode> = [];
+  const boundaryNode: void | ReplayNode =
+    trackedPostpones.workingMap.get(boundaryKeyPath);
+  if (boundaryNode === undefined) {
+    const suspenseBoundary: ReplaySuspenseBoundary = [
+      boundaryKeyPath[1],
+      boundaryKeyPath[2],
+      children,
+      null,
+      fallbackReplayNode,
+      boundary.rootSegmentID,
+    ];
+    trackedPostpones.workingMap.set(boundaryKeyPath, suspenseBoundary);
+    addToReplayParent(suspenseBoundary, boundaryKeyPath[0], trackedPostpones);
+    return suspenseBoundary;
+  } else {
+    // Upgrade to ReplaySuspenseBoundary.
+    const suspenseBoundary: ReplaySuspenseBoundary = (boundaryNode: any);
+    suspenseBoundary[4] = fallbackReplayNode;
+    suspenseBoundary[5] = boundary.rootSegmentID;
+    return suspenseBoundary;
+  }
+}
+
 function trackPostpone(
   request: Request,
   trackedPostpones: PostponedHoles,
@@ -3796,22 +3839,12 @@ function trackPostpone(
   }
 
   if (boundary !== null && boundary.status === PENDING) {
-    boundary.status = POSTPONED;
-    // We need to eagerly assign it an ID because we'll need to refer to
-    // it before flushing and we know that we can't inline it.
-    boundary.rootSegmentID = request.nextSegmentId++;
-
-    const boundaryKeyPath = boundary.trackedContentKeyPath;
-    if (boundaryKeyPath === null) {
-      throw new Error(
-        'It should not be possible to postpone at the root. This is a bug in React.',
-      );
-    }
-
-    const fallbackReplayNode = boundary.trackedFallbackNode;
-
-    const children: Array<ReplayNode> = [];
-    if (boundaryKeyPath === keyPath && task.childIndex === -1) {
+    const boundaryNode = trackPostponedBoundary(
+      request,
+      trackedPostpones,
+      boundary,
+    );
+    if (boundary.trackedContentKeyPath === keyPath && task.childIndex === -1) {
       // Assign ID
       if (segment.id === -1) {
         if (segment.parentFlushed) {
@@ -3823,39 +3856,10 @@ function trackPostpone(
         }
       }
       // We postponed directly inside the Suspense boundary so we mark this for resuming.
-      const boundaryNode: ReplaySuspenseBoundary = [
-        boundaryKeyPath[1],
-        boundaryKeyPath[2],
-        children,
-        segment.id,
-        fallbackReplayNode,
-        boundary.rootSegmentID,
-      ];
-      trackedPostpones.workingMap.set(boundaryKeyPath, boundaryNode);
-      addToReplayParent(boundaryNode, boundaryKeyPath[0], trackedPostpones);
+      boundaryNode[3] = segment.id;
       return;
-    } else {
-      let boundaryNode: void | ReplayNode =
-        trackedPostpones.workingMap.get(boundaryKeyPath);
-      if (boundaryNode === undefined) {
-        boundaryNode = [
-          boundaryKeyPath[1],
-          boundaryKeyPath[2],
-          children,
-          null,
-          fallbackReplayNode,
-          boundary.rootSegmentID,
-        ];
-        trackedPostpones.workingMap.set(boundaryKeyPath, boundaryNode);
-        addToReplayParent(boundaryNode, boundaryKeyPath[0], trackedPostpones);
-      } else {
-        // Upgrade to ReplaySuspenseBoundary.
-        const suspenseBoundary: ReplaySuspenseBoundary = (boundaryNode: any);
-        suspenseBoundary[4] = fallbackReplayNode;
-        suspenseBoundary[5] = boundary.rootSegmentID;
-      }
-      // Fall through to add the child node.
     }
+    // Otherwise, fall through to add the child node.
   }
 
   // We know that this will leave a hole so we might as well assign an ID now.