Create new flag to disable the last part of the notifications for mount hooks on Android

packages/react-native/React/Fabric/RCTSurfacePresenter.mm

@@ -265,10 +265,6 @@ - (RCTScheduler *)_createScheduler
     CoreFeatures::enableGranularScrollViewStateUpdatesIOS = true;
   }
 
-  if (reactNativeConfig && reactNativeConfig->getBool("react_fabric:enable_mount_hooks_ios")) {
-    CoreFeatures::enableMountHooks = true;
-  }
-
   if (reactNativeConfig && reactNativeConfig->getBool("react_fabric:enable_cloneless_state_progression")) {
     CoreFeatures::enableClonelessStateProgression = true;
   }

packages/react-native/ReactAndroid/api/ReactAndroid.api

@@ -1910,7 +1910,6 @@ public class com/facebook/react/config/ReactFeatureFlags {
 	public static field enableFabricPendingEventQueue Z
 	public static field enableFabricRenderer Z
 	public static field enableFabricRendererExclusively Z
-	public static field enableMountHooks Z
 	public static field enableRemoveDeleteTreeInstruction Z
 	public static field enableTextSpannableCache Z
 	public static field enableViewRecycling Z

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java

@@ -109,9 +109,6 @@ public class ReactFeatureFlags {
    */
   public static boolean enableRemoveDeleteTreeInstruction = false;
 
-  /** Report mount operations from the host platform to notify mount hooks. */
-  public static boolean enableMountHooks = false;
-
   /** Use native view configs in bridgeless mode. */
   public static boolean useNativeViewConfigsInBridgelessMode = false;
 

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java

@@ -65,6 +65,7 @@
 import com.facebook.react.fabric.mounting.mountitems.MountItem;
 import com.facebook.react.fabric.mounting.mountitems.MountItemFactory;
 import com.facebook.react.interfaces.fabric.SurfaceHandler;
+import com.facebook.react.internal.featureflags.ReactNativeFeatureFlags;
 import com.facebook.react.internal.interop.InteropEventEmitter;
 import com.facebook.react.modules.core.ReactChoreographer;
 import com.facebook.react.modules.i18nmanager.I18nUtil;
@@ -91,7 +92,6 @@
 import java.util.Map;
 import java.util.Queue;
 import java.util.concurrent.CopyOnWriteArrayList;
-import java.util.concurrent.atomic.AtomicBoolean;
 
 /**
  * We instruct ProGuard not to strip out any fields or methods, because many of these methods are
@@ -173,7 +173,8 @@ public class FabricUIManager implements UIManager, LifecycleEventListener {
   @NonNull
   private final CopyOnWriteArrayList<UIManagerListener> mListeners = new CopyOnWriteArrayList<>();
 
-  @NonNull private final AtomicBoolean mMountNotificationScheduled = new AtomicBoolean(false);
+  private boolean mMountNotificationScheduled = false;
+  private final List<Integer> mMountedSurfaceIds = new ArrayList<>();
 
   @ThreadConfined(UI)
   @NonNull
@@ -1203,54 +1204,57 @@ public Map<String, Long> getPerformanceCounters() {
   }
 
   private class MountItemDispatchListener implements MountItemDispatcher.ItemDispatchListener {
+    @UiThread
+    @ThreadConfined(UI)
     @Override
     public void willMountItems(@Nullable List<MountItem> mountItems) {
       for (UIManagerListener listener : mListeners) {
         listener.willMountItems(FabricUIManager.this);
       }
     }
 
+    @UiThread
+    @ThreadConfined(UI)
     @Override
     public void didMountItems(@Nullable List<MountItem> mountItems) {
       for (UIManagerListener listener : mListeners) {
         listener.didMountItems(FabricUIManager.this);
       }
 
-      if (!ReactFeatureFlags.enableMountHooks) {
+      if (!ReactNativeFeatureFlags.enableMountHooksAndroid()
+          || mountItems == null
+          || mountItems.isEmpty()) {
         return;
       }
 
-      boolean mountNotificationScheduled = mMountNotificationScheduled.getAndSet(true);
-      if (!mountNotificationScheduled) {
+      // Collect surface IDs for all the mount items
+      for (MountItem mountItem : mountItems) {
+        if (mountItem != null && !mMountedSurfaceIds.contains(mountItem.getSurfaceId())) {
+          mMountedSurfaceIds.add(mountItem.getSurfaceId());
+        }
+      }
+
+      if (!mMountNotificationScheduled && !mMountedSurfaceIds.isEmpty()) {
         // Notify mount when the effects are visible and prevent mount hooks to
         // delay paint.
         UiThreadUtil.getUiThreadHandler()
             .postAtFrontOfQueue(
                 new Runnable() {
                   @Override
                   public void run() {
-                    mMountNotificationScheduled.set(false);
-
-                    if (mDestroyed) {
-                      return;
-                    }
+                    mMountNotificationScheduled = false;
 
                     final @Nullable Binding binding = mBinding;
-                    if (mountItems == null || binding == null) {
+                    if (binding == null || mDestroyed) {
+                      mMountedSurfaceIds.clear();
                       return;
                     }
 
-                    // Collect surface IDs for all the mount items
-                    List<Integer> surfaceIds = new ArrayList<>();
-                    for (MountItem mountItem : mountItems) {
-                      if (mountItem != null && !surfaceIds.contains(mountItem.getSurfaceId())) {
-                        surfaceIds.add(mountItem.getSurfaceId());
-                      }
-                    }
-
-                    for (int surfaceId : surfaceIds) {
+                    for (int surfaceId : mMountedSurfaceIds) {
                       binding.reportMount(surfaceId);
                     }
+
+                    mMountedSurfaceIds.clear();
                   }
                 });
       }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<6d6fd79bdd221b3aeed0057ac756ee92>>
+ * @generated SignedSource<<a3cb24f7faddd86beb617c8314c1bfed>>
  */
 
 /**
@@ -64,6 +64,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun enableMicrotasks(): Boolean = accessor.enableMicrotasks()
 
+  /**
+   * Enables the notification of mount operations to mount hooks on Android.
+   */
+  @JvmStatic
+  public fun enableMountHooksAndroid(): Boolean = accessor.enableMountHooksAndroid()
+
   /**
    * Uses new, deduplicated logic for constructing Android Spannables from text fragments
    */
@@ -82,6 +88,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun inspectorEnableModernCDPRegistry(): Boolean = accessor.inspectorEnableModernCDPRegistry()
 
+  /**
+   * This is a temporary flag to disable part of the mount hooks pipeline to investigate a crash.
+   */
+  @JvmStatic
+  public fun skipMountHookNotifications(): Boolean = accessor.skipMountHookNotifications()
+
   /**
    * When enabled, it uses the modern fork of RuntimeScheduler that allows scheduling tasks with priorities from any thread.
    */

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<45776de0416f833eed9bb84d6b7d1052>>
+ * @generated SignedSource<<8539cf7ba13ab52ca878efd2c4858d7a>>
  */
 
 /**
@@ -26,9 +26,11 @@ public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccesso
   private var enableCustomDrawOrderFabricCache: Boolean? = null
   private var enableFixForClippedSubviewsCrashCache: Boolean? = null
   private var enableMicrotasksCache: Boolean? = null
+  private var enableMountHooksAndroidCache: Boolean? = null
   private var enableSpannableBuildingUnificationCache: Boolean? = null
   private var inspectorEnableCxxInspectorPackagerConnectionCache: Boolean? = null
   private var inspectorEnableModernCDPRegistryCache: Boolean? = null
+  private var skipMountHookNotificationsCache: Boolean? = null
   private var useModernRuntimeSchedulerCache: Boolean? = null
 
   override fun commonTestFlag(): Boolean {
@@ -85,6 +87,15 @@ public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccesso
     return cached
   }
 
+  override fun enableMountHooksAndroid(): Boolean {
+    var cached = enableMountHooksAndroidCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.enableMountHooksAndroid()
+      enableMountHooksAndroidCache = cached
+    }
+    return cached
+  }
+
   override fun enableSpannableBuildingUnification(): Boolean {
     var cached = enableSpannableBuildingUnificationCache
     if (cached == null) {
@@ -112,6 +123,15 @@ public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccesso
     return cached
   }
 
+  override fun skipMountHookNotifications(): Boolean {
+    var cached = skipMountHookNotificationsCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.skipMountHookNotifications()
+      skipMountHookNotificationsCache = cached
+    }
+    return cached
+  }
+
   override fun useModernRuntimeScheduler(): Boolean {
     var cached = useModernRuntimeSchedulerCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<f9c16b18d93c786db2c5a90c0c4340f6>>
+ * @generated SignedSource<<cd7257d4b1414f7aacd02a79b9295a46>>
  */
 
 /**
@@ -40,12 +40,16 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun enableMicrotasks(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun enableMountHooksAndroid(): Boolean
+
   @DoNotStrip @JvmStatic public external fun enableSpannableBuildingUnification(): Boolean
 
   @DoNotStrip @JvmStatic public external fun inspectorEnableCxxInspectorPackagerConnection(): Boolean
 
   @DoNotStrip @JvmStatic public external fun inspectorEnableModernCDPRegistry(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun skipMountHookNotifications(): Boolean
+
   @DoNotStrip @JvmStatic public external fun useModernRuntimeScheduler(): Boolean
 
   @DoNotStrip @JvmStatic public external fun override(provider: Any)

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<4f72683fb2a832d5b77ee2cb37343526>>
+ * @generated SignedSource<<99263973c4a06fdc91e7c9edf4aa4e19>>
  */
 
 /**
@@ -35,11 +35,15 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun enableMicrotasks(): Boolean = false
 
+  override fun enableMountHooksAndroid(): Boolean = false
+
   override fun enableSpannableBuildingUnification(): Boolean = false
 
   override fun inspectorEnableCxxInspectorPackagerConnection(): Boolean = false
 
   override fun inspectorEnableModernCDPRegistry(): Boolean = false
 
+  override fun skipMountHookNotifications(): Boolean = false
+
   override fun useModernRuntimeScheduler(): Boolean = false
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<5fd54183222961f5557dbe0ac111a6ec>>
+ * @generated SignedSource<<e8550b0c2494b223b82e6fab0a827d53>>
  */
 
 /**
@@ -30,9 +30,11 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
   private var enableCustomDrawOrderFabricCache: Boolean? = null
   private var enableFixForClippedSubviewsCrashCache: Boolean? = null
   private var enableMicrotasksCache: Boolean? = null
+  private var enableMountHooksAndroidCache: Boolean? = null
   private var enableSpannableBuildingUnificationCache: Boolean? = null
   private var inspectorEnableCxxInspectorPackagerConnectionCache: Boolean? = null
   private var inspectorEnableModernCDPRegistryCache: Boolean? = null
+  private var skipMountHookNotificationsCache: Boolean? = null
   private var useModernRuntimeSchedulerCache: Boolean? = null
 
   override fun commonTestFlag(): Boolean {
@@ -95,6 +97,16 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun enableMountHooksAndroid(): Boolean {
+    var cached = enableMountHooksAndroidCache
+    if (cached == null) {
+      cached = currentProvider.enableMountHooksAndroid()
+      accessedFeatureFlags.add("enableMountHooksAndroid")
+      enableMountHooksAndroidCache = cached
+    }
+    return cached
+  }
+
   override fun enableSpannableBuildingUnification(): Boolean {
     var cached = enableSpannableBuildingUnificationCache
     if (cached == null) {
@@ -125,6 +137,16 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun skipMountHookNotifications(): Boolean {
+    var cached = skipMountHookNotificationsCache
+    if (cached == null) {
+      cached = currentProvider.skipMountHookNotifications()
+      accessedFeatureFlags.add("skipMountHookNotifications")
+      skipMountHookNotificationsCache = cached
+    }
+    return cached
+  }
+
   override fun useModernRuntimeScheduler(): Boolean {
     var cached = useModernRuntimeSchedulerCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<c4f4d28210d5437839616d49120eb921>>
+ * @generated SignedSource<<268a87860fea5f281567d2142f90b0d4>>
  */
 
 /**
@@ -35,11 +35,15 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun enableMicrotasks(): Boolean
 
+  @DoNotStrip public fun enableMountHooksAndroid(): Boolean
+
   @DoNotStrip public fun enableSpannableBuildingUnification(): Boolean
 
   @DoNotStrip public fun inspectorEnableCxxInspectorPackagerConnection(): Boolean
 
   @DoNotStrip public fun inspectorEnableModernCDPRegistry(): Boolean
 
+  @DoNotStrip public fun skipMountHookNotifications(): Boolean
+
   @DoNotStrip public fun useModernRuntimeScheduler(): Boolean
 }