Add option to delay deletion of viewState

Summary:
changelog: [internal]

ViewState is sometimes deleted but not created again because of race condition in C++ pre-allocation and how it checks for revision to determine if createView mount item should be dispatched.

In this diff, we add an option to delay deletion of ViewState until the next commit.

Reviewed By: ShikaSD

Differential Revision: D34553174

fbshipit-source-id: e5213f1d39137fb56fc745321a7c1b28d417ea27

ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java

@@ -98,4 +98,6 @@ public class ReactFeatureFlags {
   public static boolean enableAggressiveEventEmitterCleanup = false;
 
   public static boolean insertZReorderBarriersOnViewGroupChildren = true;
+
+  public static boolean enableDelayedViewStateDeletion = false;
 }

ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/SurfaceMountingManager.java

@@ -45,6 +45,7 @@ import com.facebook.react.uimanager.ViewManager;
 import com.facebook.react.uimanager.ViewManagerRegistry;
 import com.facebook.react.views.view.ReactMapBufferViewManager;
 import com.facebook.react.views.view.ReactViewManagerWrapper;
+import java.util.HashSet;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentLinkedQueue;
@@ -72,6 +73,14 @@ public class SurfaceMountingManager {
   // This is null *until* StopSurface is called.
   private Set<Integer> mTagSetForStoppedSurface;
 
+  // C++ layer checks for prop revision and doesn't
+  // dispatch createView mount item if view pre-allocation mount item was dispatched.
+  // This leads to missing createView and pre-mature deletion of ViewState.
+  // To work around this issue, ViewState deletion is delayed until subsequent commit.
+  // If the subsequent commit accesses ViewState, it won't be deleted.
+  private Set<Integer> mSoftDeletedViewStateTags;
+  private Set<Integer> mScheduledForDeletionViewStateTags;
+
   private final int mSurfaceId;
 
   public SurfaceMountingManager(
@@ -88,6 +97,11 @@ public class SurfaceMountingManager {
     mRootViewManager = rootViewManager;
     mMountItemExecutor = mountItemExecutor;
     mThemedReactContext = reactContext;
+
+    if (ReactFeatureFlags.enableDelayedViewStateDeletion) {
+      mSoftDeletedViewStateTags = new HashSet();
+      mScheduledForDeletionViewStateTags = new HashSet();
+    }
   }
 
   public boolean isStopped() {
@@ -913,6 +927,23 @@ public class SurfaceMountingManager {
     }
   }
 
+  @UiThread
+  public void didUpdateViews() {
+    if (ReactFeatureFlags.enableDelayedViewStateDeletion) {
+      for (Integer reactTag : mScheduledForDeletionViewStateTags) {
+        // To delete we simply remove the tag from the registry.
+        // We want to rely on the correct set of MountInstructions being sent to the platform,
+        // or StopSurface being called, so we do not handle deleting descendents of the View.
+        ViewState viewState = mTagToViewState.remove(reactTag);
+        if (viewState != null) {
+          onViewStateDeleted(viewState);
+        }
+      }
+      mScheduledForDeletionViewStateTags = mSoftDeletedViewStateTags;
+      mSoftDeletedViewStateTags = new HashSet();
+    }
+  }
+
   @UiThread
   public void deleteView(int reactTag) {
     UiThreadUtil.assertOnUiThread();
@@ -930,12 +961,16 @@ public class SurfaceMountingManager {
       return;
     }
 
-    // To delete we simply remove the tag from the registry.
-    // We want to rely on the correct set of MountInstructions being sent to the platform,
-    // or StopSurface being called, so we do not handle deleting descendents of the View.
-    mTagToViewState.remove(reactTag);
+    if (ReactFeatureFlags.enableDelayedViewStateDeletion) {
+      mSoftDeletedViewStateTags.add(reactTag);
+    } else {
+      // To delete we simply remove the tag from the registry.
+      // We want to rely on the correct set of MountInstructions being sent to the platform,
+      // or StopSurface being called, so we do not handle deleting descendents of the View.
+      mTagToViewState.remove(reactTag);
 
-    onViewStateDeleted(viewState);
+      onViewStateDeleted(viewState);
+    }
   }
 
   @UiThread
@@ -984,6 +1019,9 @@ public class SurfaceMountingManager {
     if (viewState == null) {
       throw new RetryableMountingLayerException("Unable to find viewState for tag " + tag);
     }
+    if (ReactFeatureFlags.enableDelayedViewStateDeletion) {
+      mScheduledForDeletionViewStateTags.remove(tag);
+    }
     return viewState;
   }
 
@@ -991,6 +1029,9 @@ public class SurfaceMountingManager {
     if (mTagToViewState == null) {
       return null;
     }
+    if (ReactFeatureFlags.enableDelayedViewStateDeletion) {
+      mScheduledForDeletionViewStateTags.remove(tag);
+    }
     return mTagToViewState.get(tag);
   }
 

ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/mountitems/IntBufferBatchMountItem.java

@@ -188,6 +188,8 @@ public class IntBufferBatchMountItem implements MountItem {
       }
     }
 
+    surfaceMountingManager.didUpdateViews();
+
     endMarkers();
   }