Re-land refactored implementation of mutation phase in new fork

packages/react-reconciler/src/ReactChildFiber.new.js

@@ -282,22 +282,13 @@ function ChildReconciler(shouldTrackSideEffects) {
     childToDelete.nextEffect = null;
     childToDelete.flags = (childToDelete.flags & StaticMask) | Deletion;
 
-    let deletions = returnFiber.deletions;
+    const deletions = returnFiber.deletions;
     if (deletions === null) {
-      deletions = returnFiber.deletions = [childToDelete];
+      returnFiber.deletions = [childToDelete];
       returnFiber.flags |= ChildDeletion;
     } else {
       deletions.push(childToDelete);
     }
-    // Stash a reference to the return fiber's deletion array on each of the
-    // deleted children. This is really weird, but it's a temporary workaround
-    // while we're still using the effect list to traverse effect fibers. A
-    // better workaround would be to follow the `.return` pointer in the commit
-    // phase, but unfortunately we can't assume that `.return` points to the
-    // correct fiber, even in the commit phase, because `findDOMNode` might
-    // mutate it.
-    // TODO: Remove this line.
-    childToDelete.deletions = deletions;
   }
 
   function deleteRemainingChildren(

packages/react-reconciler/src/ReactFiberBeginWork.new.js

@@ -2203,14 +2203,13 @@ function updateSuspensePrimaryChildren(
     currentFallbackChildFragment.flags =
       (currentFallbackChildFragment.flags & StaticMask) | Deletion;
     workInProgress.firstEffect = workInProgress.lastEffect = currentFallbackChildFragment;
-    let deletions = workInProgress.deletions;
+    const deletions = workInProgress.deletions;
     if (deletions === null) {
-      deletions = workInProgress.deletions = [currentFallbackChildFragment];
+      workInProgress.deletions = [currentFallbackChildFragment];
       workInProgress.flags |= ChildDeletion;
     } else {
       deletions.push(currentFallbackChildFragment);
     }
-    currentFallbackChildFragment.deletions = deletions;
   }
 
   workInProgress.child = primaryChildFragment;
@@ -3194,14 +3193,13 @@ function remountFiber(
     current.nextEffect = null;
     current.flags = (current.flags & StaticMask) | Deletion;
 
-    let deletions = returnFiber.deletions;
+    const deletions = returnFiber.deletions;
     if (deletions === null) {
-      deletions = returnFiber.deletions = [current];
+      returnFiber.deletions = [current];
       returnFiber.flags |= ChildDeletion;
     } else {
       deletions.push(current);
     }
-    current.deletions = deletions;
 
     newWorkInProgress.flags |= Placement;
 

packages/react-reconciler/src/ReactFiberCommitWork.new.js

@@ -66,12 +66,16 @@ import {
   NoFlags,
   ContentReset,
   Placement,
+  PlacementAndUpdate,
   ChildDeletion,
   Snapshot,
   Update,
   Callback,
   Ref,
+  Hydrating,
+  HydratingAndUpdate,
   Passive,
+  MutationMask,
   PassiveMask,
   LayoutMask,
   PassiveUnmountPendingDev,
@@ -1841,6 +1845,172 @@ function commitResetTextContent(current: Fiber) {
   resetTextContent(current.stateNode);
 }
 
+export function commitMutationEffects(
+  root: FiberRoot,
+  renderPriorityLevel: ReactPriorityLevel,
+  firstChild: Fiber,
+) {
+  nextEffect = firstChild;
+  commitMutationEffects_begin(root, renderPriorityLevel);
+}
+
+function commitMutationEffects_begin(
+  root: FiberRoot,
+  renderPriorityLevel: ReactPriorityLevel,
+) {
+  while (nextEffect !== null) {
+    const fiber = nextEffect;
+
+    // TODO: Should wrap this in flags check, too, as optimization
+    const deletions = fiber.deletions;
+    if (deletions !== null) {
+      for (let i = 0; i < deletions.length; i++) {
+        const childToDelete = deletions[i];
+        if (__DEV__) {
+          invokeGuardedCallback(
+            null,
+            commitDeletion,
+            null,
+            root,
+            childToDelete,
+            renderPriorityLevel,
+          );
+          if (hasCaughtError()) {
+            const error = clearCaughtError();
+            captureCommitPhaseError(childToDelete, error);
+          }
+        } else {
+          try {
+            commitDeletion(root, childToDelete, renderPriorityLevel);
+          } catch (error) {
+            captureCommitPhaseError(childToDelete, error);
+          }
+        }
+      }
+    }
+
+    const child = fiber.child;
+    if ((fiber.subtreeFlags & MutationMask) !== NoFlags && child !== null) {
+      ensureCorrectReturnPointer(child, fiber);
+      nextEffect = child;
+    } else {
+      commitMutationEffects_complete(root, renderPriorityLevel);
+    }
+  }
+}
+
+function commitMutationEffects_complete(
+  root: FiberRoot,
+  renderPriorityLevel: ReactPriorityLevel,
+) {
+  while (nextEffect !== null) {
+    const fiber = nextEffect;
+    if (__DEV__) {
+      setCurrentDebugFiberInDEV(fiber);
+      invokeGuardedCallback(
+        null,
+        commitMutationEffectsOnFiber,
+        null,
+        fiber,
+        root,
+        renderPriorityLevel,
+      );
+      if (hasCaughtError()) {
+        const error = clearCaughtError();
+        captureCommitPhaseError(fiber, error);
+      }
+      resetCurrentDebugFiberInDEV();
+    } else {
+      try {
+        commitMutationEffectsOnFiber(fiber, root, renderPriorityLevel);
+      } catch (error) {
+        captureCommitPhaseError(fiber, error);
+      }
+    }
+
+    const sibling = fiber.sibling;
+    if (sibling !== null) {
+      ensureCorrectReturnPointer(sibling, fiber.return);
+      nextEffect = sibling;
+      return;
+    }
+
+    nextEffect = fiber.return;
+  }
+}
+
+function commitMutationEffectsOnFiber(
+  finishedWork: Fiber,
+  root: FiberRoot,
+  renderPriorityLevel: ReactPriorityLevel,
+) {
+  const flags = finishedWork.flags;
+
+  if (flags & ContentReset) {
+    commitResetTextContent(finishedWork);
+  }
+
+  if (flags & Ref) {
+    const current = finishedWork.alternate;
+    if (current !== null) {
+      commitDetachRef(current);
+    }
+    if (enableScopeAPI) {
+      // TODO: This is a temporary solution that allowed us to transition away
+      // from React Flare on www.
+      if (finishedWork.tag === ScopeComponent) {
+        commitAttachRef(finishedWork);
+      }
+    }
+  }
+
+  // The following switch statement is only concerned about placement,
+  // updates, and deletions. To avoid needing to add a case for every possible
+  // bitmap value, we remove the secondary effects from the effect tag and
+  // switch on that value.
+  const primaryFlags = flags & (Placement | Update | Hydrating);
+  outer: switch (primaryFlags) {
+    case Placement: {
+      commitPlacement(finishedWork);
+      // Clear the "placement" from effect tag so that we know that this is
+      // inserted, before any life-cycles like componentDidMount gets called.
+      // TODO: findDOMNode doesn't rely on this any more but isMounted does
+      // and isMounted is deprecated anyway so we should be able to kill this.
+      finishedWork.flags &= ~Placement;
+      break;
+    }
+    case PlacementAndUpdate: {
+      // Placement
+      commitPlacement(finishedWork);
+      // Clear the "placement" from effect tag so that we know that this is
+      // inserted, before any life-cycles like componentDidMount gets called.
+      finishedWork.flags &= ~Placement;
+
+      // Update
+      const current = finishedWork.alternate;
+      commitWork(current, finishedWork);
+      break;
+    }
+    case Hydrating: {
+      finishedWork.flags &= ~Hydrating;
+      break;
+    }
+    case HydratingAndUpdate: {
+      finishedWork.flags &= ~Hydrating;
+
+      // Update
+      const current = finishedWork.alternate;
+      commitWork(current, finishedWork);
+      break;
+    }
+    case Update: {
+      const current = finishedWork.alternate;
+      commitWork(current, finishedWork);
+      break;
+    }
+  }
+}
+
 export function commitLayoutEffects(
   finishedWork: Fiber,
   root: FiberRoot,

packages/react-reconciler/src/ReactFiberHydrationContext.new.js

@@ -144,14 +144,13 @@ function deleteHydratableInstance(
     returnFiber.firstEffect = returnFiber.lastEffect = childToDelete;
   }
 
-  let deletions = returnFiber.deletions;
+  const deletions = returnFiber.deletions;
   if (deletions === null) {
-    deletions = returnFiber.deletions = [childToDelete];
+    returnFiber.deletions = [childToDelete];
     returnFiber.flags |= ChildDeletion;
   } else {
     deletions.push(childToDelete);
   }
-  childToDelete.deletions = deletions;
 }
 
 function insertNonHydratedInstance(returnFiber: Fiber, fiber: Fiber) {