Move event dispatch logic from FabricUIManager into SurfaceMountingManager (facebook#56659)

Summary:
Pull Request resolved: facebook#56659

Refactor: consolidate the event dispatch decision (enqueue vs direct dispatch) into `SurfaceMountingManager.dispatchEvent`, removing the 3-way branching from `FabricUIManager.receiveEvent`. The sync event path remains in `FabricUIManager`.

This moves `getEventEmitter`, `getViewExists`, and `enqueuePendingEvent` calls behind a single `dispatchEvent` entry point, making the ordering logic fully encapsulated in `SurfaceMountingManager`.

Changelog: [Internal]

Reviewed By: zeyap

Differential Revision: D103007280

fbshipit-source-id: 15eed04c0d936836d2fedeaff09254266c0f0528

Author: javache

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

@@ -1199,42 +1199,22 @@ public void receiveEvent(
       return;
     }
 
-    EventEmitterWrapper eventEmitter = mMountingManager.getEventEmitter(surfaceId, reactTag);
-    if (eventEmitter == null) {
-      if (mMountingManager.getViewExists(reactTag)) {
-        // The view is pre-allocated and created. However, it hasn't been mounted yet. We will have
-        // access to the event emitter later when the view is mounted. For now just save the event
-        // in the view state and trigger it later.
-        mMountingManager.enqueuePendingEvent(
-            surfaceId,
-            reactTag,
-            eventName,
-            canCoalesceEvent,
-            params,
-            eventCategory,
-            eventTimestamp);
-      } else {
-        // This can happen if the view has disappeared from the screen (because of async events)
-        FLog.i(TAG, "Unable to invoke event: " + eventName + " for reactTag: " + reactTag);
-      }
-      return;
-    }
-
     if (experimentalIsSynchronous) {
       UiThreadUtil.assertOnUiThread();
-      // add() returns true only if there are no equivalent events already in the set
-      boolean firstEventForFrame =
-          mSynchronousEvents.add(new SynchronousEvent(surfaceId, reactTag, eventName));
-      if (firstEventForFrame) {
-        eventEmitter.dispatchEventSynchronously(eventName, params, eventTimestamp);
-      }
-    } else {
-      if (canCoalesceEvent) {
-        eventEmitter.dispatchUnique(eventName, params, eventTimestamp);
-      } else {
-        eventEmitter.dispatch(eventName, params, eventCategory, eventTimestamp);
+      EventEmitterWrapper eventEmitter = mMountingManager.getEventEmitter(surfaceId, reactTag);
+      if (eventEmitter != null) {
+        // add() returns true only if there are no equivalent events already in the set
+        boolean firstEventForFrame =
+            mSynchronousEvents.add(new SynchronousEvent(surfaceId, reactTag, eventName));
+        if (firstEventForFrame) {
+          eventEmitter.dispatchEventSynchronously(eventName, params, eventTimestamp);
+        }
+        return;
       }
     }
+
+    mMountingManager.dispatchEvent(
+        surfaceId, reactTag, eventName, canCoalesceEvent, params, eventCategory, eventTimestamp);
   }
 
   @Override

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/MountingManager.kt

@@ -327,7 +327,7 @@ internal class MountingManager(
               attachmentsPositions,
           )
 
-  fun enqueuePendingEvent(
+  fun dispatchEvent(
       surfaceId: Int,
       reactTag: Int,
       eventName: String,
@@ -338,22 +338,16 @@ internal class MountingManager(
   ) {
     val smm = getSurfaceMountingManager(surfaceId, reactTag)
     if (smm == null) {
-      FLog.d(
+      FLog.i(
           TAG,
-          "Cannot queue event without valid surface mounting manager for tag: %d, surfaceId: %d",
+          "Unable to invoke event %s for tag [%d] in surfaceId [%d]",
+          eventName,
           reactTag,
           surfaceId,
       )
       return
     }
-    smm.enqueuePendingEvent(
-        reactTag,
-        eventName,
-        canCoalesceEvent,
-        params,
-        eventCategory,
-        eventTimestamp,
-    )
+    smm.dispatchEvent(reactTag, eventName, canCoalesceEvent, params, eventCategory, eventTimestamp)
   }
 
   private fun getSurfaceMountingManager(surfaceId: Int, reactTag: Int): SurfaceMountingManager? =

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/SurfaceMountingManager.kt

@@ -1241,6 +1241,45 @@ internal constructor(
     }
   }
 
+  @AnyThread
+  internal fun dispatchEvent(
+      reactTag: Int,
+      eventName: String,
+      canCoalesceEvent: Boolean,
+      params: WritableMap?,
+      @EventCategoryDef eventCategory: Int,
+      eventTimestamp: Long,
+  ) {
+    val viewState = registryGet(reactTag)
+    if (viewState == null) {
+      // This can happen if the view has disappeared from the screen (because of async events)
+      FLog.i(TAG, "Unable to invoke event: %s for reactTag: %d", eventName, reactTag)
+      return
+    }
+
+    val eventEmitter = viewState.eventEmitter
+    if (eventEmitter == null) {
+      // The view is pre-allocated and created. However, it hasn't been mounted yet. We will have
+      // access to the event emitter later when the view is mounted. For now just save the event
+      // in the view state and trigger it later.
+      enqueuePendingEvent(
+          reactTag,
+          eventName,
+          canCoalesceEvent,
+          params,
+          eventCategory,
+          eventTimestamp,
+      )
+      return
+    }
+
+    if (canCoalesceEvent) {
+      eventEmitter.dispatchUnique(eventName, params, eventTimestamp)
+    } else {
+      eventEmitter.dispatch(eventName, params, eventCategory, eventTimestamp)
+    }
+  }
+
   public fun markActiveTouchForTag(reactTag: Int): Unit {
     viewsWithActiveTouches.add(reactTag)
   }