perf(android): gate UIManager constants cache

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

@@ -19,7 +19,6 @@
 import com.facebook.react.modules.core.PermissionListener;
 import com.facebook.react.util.AndroidVersion;
 import org.jetbrains.annotations.NotNull;
-import com.facebook.react.uimanager.UIManagerConstantsCache;
 
 /** Base Activity for React Native applications. */
 public abstract class ReactActivity extends AppCompatActivity
@@ -59,7 +58,6 @@ protected ReactActivityDelegate createReactActivityDelegate() {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
-    UIManagerConstantsCache.getInstance().init(this);
     mDelegate.onCreate(savedInstanceState);
     if (AndroidVersion.isAtLeastTargetSdk36(this)) {
       getOnBackPressedDispatcher().addCallback(this, mBackPressedCallback);

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactInstance.kt

@@ -220,6 +220,7 @@ internal class ReactInstance(
     // initialized.
     // This happens inside getTurboModuleManagerDelegate getter.
     if (ReactNativeFeatureFlags.useNativeViewConfigsInBridgelessMode()) {
+      val customBubblingEvents: MutableMap<String, Any> = HashMap()
       val customDirectEvents: MutableMap<String, Any> = HashMap()
 
       UIConstantsProviderBinding.install(
@@ -239,19 +240,30 @@ internal class ReactInstance(
             getConstantsForViewManager(viewManager, customDirectEvents)
           },
           {
-            UIManagerConstantsCache.getInstance().getUIManagerConstantsAsWritableMap()
-                ?: run {
-                  val viewManagers: List<ViewManager<*, *>> =
-                      ArrayList(viewManagerResolver.eagerViewManagerMap.values)
-                  val constants = createConstants(viewManagers, customDirectEvents)
-
-                  val lazyViewManagers = viewManagerResolver.lazyViewManagerNames
-                  if (!lazyViewManagers.isEmpty()) {
-                    constants["ViewManagerNames"] = ArrayList(lazyViewManagers)
-                    constants["LazyViewManagersEnabled"] = true
-                  }
-                  Arguments.makeNativeMap(constants)
-                }
+            val constantsCache = UIManagerConstantsCache.getInstance()
+            val cachedConstants = constantsCache.getUIManagerConstantsAsWritableMap()
+            if (cachedConstants != null) {
+              cachedConstants
+            } else {
+              val viewManagers: List<ViewManager<*, *>> =
+                  ArrayList(viewManagerResolver.eagerViewManagerMap.values)
+              val constants =
+                  createConstants(viewManagers, customBubblingEvents, customDirectEvents)
+
+              val lazyViewManagers = viewManagerResolver.lazyViewManagerNames
+              if (!lazyViewManagers.isEmpty()) {
+                constants["ViewManagerNames"] = ArrayList(lazyViewManagers)
+                constants["LazyViewManagersEnabled"] = true
+              }
+
+              // Persist only after the constants are complete so a cache hit returns the exact
+              // same shape as the miss path.
+              constantsCache.saveConstantsAndBubblingEventsTypes(
+                  constants,
+                  customBubblingEvents,
+              )
+              Arguments.makeNativeMap(constants)
+            }
           },
       )
     }
@@ -598,6 +610,7 @@ internal class ReactInstance(
 
     private fun createConstants(
         viewManagers: List<ViewManager<in Nothing, in Nothing>>,
+        customBubblingEvents: MutableMap<String, Any>?,
         customDirectEvents: MutableMap<String, Any>?,
     ): MutableMap<String, Any> {
       ReactMarker.logMarker(ReactMarkerConstants.CREATE_UI_MANAGER_MODULE_CONSTANTS_START)
@@ -607,7 +620,7 @@ internal class ReactInstance(
       try {
         return UIManagerModuleConstantsHelper.createConstants(
             viewManagers,
-            null,
+            customBubblingEvents,
             customDirectEvents,
         )
       } finally {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerConstantsCache.java

@@ -64,6 +64,9 @@ public class UIManagerConstantsCache {
     /** Ensures init(...) is only done once. */
     private volatile boolean initCalled = false;
 
+    /** Allows the host application to keep the cache fully disabled for an experiment control. */
+    private volatile boolean cacheEnabled = false;
+
     private String cacheVersionName = null;
 
     private UIManagerConstantsCache() {
@@ -75,18 +78,33 @@ public static UIManagerConstantsCache getInstance() {
     }
 
     /**
-     * Must be called (once) from Application or MainActivity before any UIManager
-     * constants are accessed. This kicks off:
+     * Must be called once from Application before any UIManager constants are accessed. This kicks
+     * off:
      *   1) MMKV.initialize(...)
      *   2) A background thread that reads two MMKV keys, parses them → Maps,
      *      and countDown()s loadLatch.
      */
-    public synchronized void init(Context appContext) {
+    public void init(Context appContext) {
+        init(appContext, true);
+    }
+
+    /**
+     * Initializes the cache when enabled. A disabled initialization permanently leaves this
+     * singleton disabled for the process so later initialization cannot change the experiment
+     * assignment.
+     */
+    public synchronized void init(Context appContext, boolean enabled) {
         if (initCalled) {
             return;
         }
+        cacheEnabled = enabled;
         initCalled = true;
 
+        if (!cacheEnabled) {
+            loadLatch.countDown();
+            return;
+        }
+
         // Its possible that the constants change between versions, so we have to keep track of the version
         // and reset the cache if it changes.
         // TODO: This can be improved by us compiling the UIManager constants at compile time
@@ -96,6 +114,8 @@ public synchronized void init(Context appContext) {
                     .versionName;
         } catch (PackageManager.NameNotFoundException e) {
             Log.e(TAG, "Failed to get app version name; continuing without caching!", e);
+            cacheEnabled = false;
+            loadLatch.countDown();
             return;
         }
 
@@ -183,6 +203,9 @@ public synchronized void init(Context appContext) {
      * @return parsed Map<String,Object> or null if none stored / parse failed.
      */
     public Map<String,Object> getCachedConstants() {
+        if (!isCacheEnabled()) {
+            return null;
+        }
         try {
             loadLatch.await();
         } catch (InterruptedException e) {
@@ -200,6 +223,9 @@ public Map<String,Object> getCachedConstants() {
      * @return parsed Map<String,Object> or null if none stored / parse failed.
      */
     public Map<String,Object> getCachedBubblingEventsTypes() {
+        if (!isCacheEnabled()) {
+            return null;
+        }
         try {
             loadLatch.await();
         } catch (InterruptedException e) {
@@ -223,6 +249,9 @@ public Map<String,Object> getCachedBubblingEventsTypes() {
      * @return WritableNativeMap or null if no full-constants available.
      */
     public WritableNativeMap getUIManagerConstantsAsWritableMap() {
+        if (!isCacheEnabled()) {
+            return null;
+        }
         try {
             loadLatch.await();
         } catch (InterruptedException e) {
@@ -246,6 +275,9 @@ public WritableNativeMap getUIManagerConstantsAsWritableMap() {
     public void saveConstantsAndBubblingEventsTypes(
             final Map<String,Object> constants,
             final Map<String,Object> bubblingEventsTypes) {
+        if (!isCacheEnabled()) {
+            return;
+        }
         if (constants == null) {
             return;
         }
@@ -282,6 +314,15 @@ public void saveConstantsAndBubblingEventsTypes(
         MMKV.defaultMMKV().encode(MMKV_KEY_VERSION, cacheVersionName);
     }
 
+    private boolean isCacheEnabled() {
+        if (!initCalled) {
+            throw new IllegalStateException(
+                    "UIManagerConstantsCache not initialized! Call init(...) first."
+            );
+        }
+        return cacheEnabled;
+    }
+
     // ────────────────────────────────────────────────────────────────────────────────
     //   JSON ↔ Map<String,Object> Helpers (identical to before)
     // ────────────────────────────────────────────────────────────────────────────────