fix(android): delete enableAccumulatedUpdatesInRawPropsAndroid and make accumulated rawProps the default

Supersedes the earlier Props.cpp patch approach. The flag's
expectedReleaseValue was already true and the non-accumulated code
path has a latent correctness bug on view-flattening un-flatten
(shadow node's rawProps gets overwritten with the latest JS patch
only, so the CREATE mount item ships a partial prop set and newly-
created native Views lose props like borderRadius). See facebook#52415.

This removes the flag entirely and promotes the accumulated behavior
to be the only behavior:

- Props::initializeDynamicProps unconditionally merges previous
  rawProps with the incoming patch.
- FabricMountingManager::getProps: non-Props-2.0 path now always emits
  full rawProps for CREATE and diffDynamicProps() for UPDATE.
- FabricMountingManager executeMount INSERT: always emits
  UpdatePropsMountItem (dropped the shouldCreateView gate that only
  ran under the old flag-off branch).
- FabricUIManagerBinding: schedulerDidFinishTransaction is a no-op
  (transactions are pulled only in schedulerShouldRenderTransactions);
  the pendingTransactions_ queue and its mutex are deleted with it.
- ConcreteComponentDescriptor: enableExclusivePropsUpdateAndroid
  no longer pivots on the accumulated flag.
- Regenerated all feature-flag accessor files (Kotlin + C++) via
  `yarn featureflags --update` to drop the API surface.

Author: janicduplessis

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<<82da59cbfb06937bba284ff1df2c64d6>>
+ * @generated SignedSource<<497133038b4ac4b29ab8d172a82285fc>>
  */
 
 /**
@@ -96,12 +96,6 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun enableAccessibilityOrder(): Boolean = accessor.enableAccessibilityOrder()
 
-  /**
-   * When enabled, Android will accumulate updates in rawProps to reduce the number of mounting instructions for cascading re-renders.
-   */
-  @JvmStatic
-  public fun enableAccumulatedUpdatesInRawPropsAndroid(): Boolean = accessor.enableAccumulatedUpdatesInRawPropsAndroid()
-
   /**
    * Enables various optimizations throughout the path of measuring text on Android.
    */

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<<b6d6b8aae3449760d857e5dd52588b03>>
+ * @generated SignedSource<<50a1a0eeaef6bb9f8a7f7491bad8f24d>>
  */
 
 /**
@@ -31,7 +31,6 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
   private var disableTextLayoutManagerCacheAndroidCache: Boolean? = null
   private var disableViewPreallocationAndroidCache: Boolean? = null
   private var enableAccessibilityOrderCache: Boolean? = null
-  private var enableAccumulatedUpdatesInRawPropsAndroidCache: Boolean? = null
   private var enableAndroidTextMeasurementOptimizationsCache: Boolean? = null
   private var enableBridgelessArchitectureCache: Boolean? = null
   private var enableCppPropsIteratorSetterCache: Boolean? = null
@@ -212,15 +211,6 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
-  override fun enableAccumulatedUpdatesInRawPropsAndroid(): Boolean {
-    var cached = enableAccumulatedUpdatesInRawPropsAndroidCache
-    if (cached == null) {
-      cached = ReactNativeFeatureFlagsCxxInterop.enableAccumulatedUpdatesInRawPropsAndroid()
-      enableAccumulatedUpdatesInRawPropsAndroidCache = cached
-    }
-    return cached
-  }
-
   override fun enableAndroidTextMeasurementOptimizations(): Boolean {
     var cached = enableAndroidTextMeasurementOptimizationsCache
     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<<7ca56a7b519e6e1619931447dcc1672a>>
+ * @generated SignedSource<<f7d31a1306d76e08aa21774c29e6e53d>>
  */
 
 /**
@@ -50,8 +50,6 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun enableAccessibilityOrder(): Boolean
 
-  @DoNotStrip @JvmStatic public external fun enableAccumulatedUpdatesInRawPropsAndroid(): Boolean
-
   @DoNotStrip @JvmStatic public external fun enableAndroidTextMeasurementOptimizations(): Boolean
 
   @DoNotStrip @JvmStatic public external fun enableBridgelessArchitecture(): Boolean

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<<fe424de3f03b5f2ee20b83896eef01b1>>
+ * @generated SignedSource<<d4a3d675fe5516c39670052b2de41175>>
  */
 
 /**
@@ -45,8 +45,6 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun enableAccessibilityOrder(): Boolean = false
 
-  override fun enableAccumulatedUpdatesInRawPropsAndroid(): Boolean = false
-
   override fun enableAndroidTextMeasurementOptimizations(): Boolean = false
 
   override fun enableBridgelessArchitecture(): 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<<0de759cf10c9d77c9938f9dac257aada>>
+ * @generated SignedSource<<5585df6f3056f8f15ed00e58f521865a>>
  */
 
 /**
@@ -35,7 +35,6 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
   private var disableTextLayoutManagerCacheAndroidCache: Boolean? = null
   private var disableViewPreallocationAndroidCache: Boolean? = null
   private var enableAccessibilityOrderCache: Boolean? = null
-  private var enableAccumulatedUpdatesInRawPropsAndroidCache: Boolean? = null
   private var enableAndroidTextMeasurementOptimizationsCache: Boolean? = null
   private var enableBridgelessArchitectureCache: Boolean? = null
   private var enableCppPropsIteratorSetterCache: Boolean? = null
@@ -227,16 +226,6 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
     return cached
   }
 
-  override fun enableAccumulatedUpdatesInRawPropsAndroid(): Boolean {
-    var cached = enableAccumulatedUpdatesInRawPropsAndroidCache
-    if (cached == null) {
-      cached = currentProvider.enableAccumulatedUpdatesInRawPropsAndroid()
-      accessedFeatureFlags.add("enableAccumulatedUpdatesInRawPropsAndroid")
-      enableAccumulatedUpdatesInRawPropsAndroidCache = cached
-    }
-    return cached
-  }
-
   override fun enableAndroidTextMeasurementOptimizations(): Boolean {
     var cached = enableAndroidTextMeasurementOptimizationsCache
     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<<dd7ae1c5f86fa273402e5b64a8636528>>
+ * @generated SignedSource<<d91e9cbbbb0ab6f2e88b21db315dfa04>>
  */
 
 /**
@@ -45,8 +45,6 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun enableAccessibilityOrder(): Boolean
 
-  @DoNotStrip public fun enableAccumulatedUpdatesInRawPropsAndroid(): Boolean
-
   @DoNotStrip public fun enableAndroidTextMeasurementOptimizations(): Boolean
 
   @DoNotStrip public fun enableBridgelessArchitecture(): Boolean

packages/react-native/ReactAndroid/src/main/jni/react/fabric/FabricMountingManager.cpp

@@ -339,15 +339,11 @@ jni::local_ref<jobject> getProps(
 
     return ReadableNativeMap::newObjectCxxArgs(std::move(diff));
   }
-  if (ReactNativeFeatureFlags::enableAccumulatedUpdatesInRawPropsAndroid()) {
-    if (oldProps == nullptr) {
-      return ReadableNativeMap::newObjectCxxArgs(newProps->rawProps);
-    } else {
-      return ReadableNativeMap::newObjectCxxArgs(
-          diffDynamicProps(oldProps->rawProps, newProps->rawProps));
-    }
+  if (oldProps == nullptr) {
+    return ReadableNativeMap::newObjectCxxArgs(newProps->rawProps);
   }
-  return ReadableNativeMap::newObjectCxxArgs(newProps->rawProps);
+  return ReadableNativeMap::newObjectCxxArgs(
+      diffDynamicProps(oldProps->rawProps, newProps->rawProps));
 }
 
 struct InstructionBuffer {
@@ -725,28 +721,15 @@ void FabricMountingManager::executeMount(
 
             bool shouldCreateView =
                 !allocatedViewTags.contains(newChildShadowView.tag);
-            if (ReactNativeFeatureFlags::
-                    enableAccumulatedUpdatesInRawPropsAndroid()) {
-              if (shouldCreateView) {
-                LOG(ERROR) << "Emitting insert for unallocated view "
-                           << newChildShadowView.tag;
-              }
-              (maintainMutationOrder ? cppCommonMountItems
-                                     : cppUpdatePropsMountItems)
-                  .push_back(
-                      CppMountItem::UpdatePropsMountItem(
-                          {}, newChildShadowView));
-            } else {
-              if (shouldCreateView) {
-                LOG(ERROR) << "Emitting insert for unallocated view "
-                           << newChildShadowView.tag;
-                (maintainMutationOrder ? cppCommonMountItems
-                                       : cppUpdatePropsMountItems)
-                    .push_back(
-                        CppMountItem::UpdatePropsMountItem(
-                            {}, newChildShadowView));
-              }
+            if (shouldCreateView) {
+              LOG(ERROR) << "Emitting insert for unallocated view "
+                         << newChildShadowView.tag;
             }
+            (maintainMutationOrder ? cppCommonMountItems
+                                   : cppUpdatePropsMountItems)
+                .push_back(
+                    CppMountItem::UpdatePropsMountItem(
+                        {}, newChildShadowView));
 
             // State
             if (newChildShadowView.state) {

packages/react-native/ReactAndroid/src/main/jni/react/fabric/FabricUIManagerBinding.cpp

@@ -620,35 +620,9 @@ FabricUIManagerBinding::getMountingManager(const char* locationHint) {
 }
 
 void FabricUIManagerBinding::schedulerDidFinishTransaction(
-    const std::shared_ptr<const MountingCoordinator>& mountingCoordinator) {
-  if (ReactNativeFeatureFlags::enableAccumulatedUpdatesInRawPropsAndroid()) {
-    // We don't do anything here. We will pull the transaction in
-    // `schedulerShouldRenderTransactions`.
-  } else {
-    // We shouldn't be pulling the transaction here (which triggers diffing of
-    // the trees to determine the mutations to run on the host platform),
-    // but we have to due to current limitations in the Android implementation.
-    auto mountingTransaction = mountingCoordinator->pullTransaction(
-        /* willPerformAsynchronously = */ true);
-    if (!mountingTransaction.has_value()) {
-      return;
-    }
-
-    std::unique_lock<std::mutex> lock(pendingTransactionsMutex_);
-    auto pendingTransaction = std::find_if(
-        pendingTransactions_.begin(),
-        pendingTransactions_.end(),
-        [&](const auto& transaction) {
-          return transaction.getSurfaceId() ==
-              mountingTransaction->getSurfaceId();
-        });
-
-    if (pendingTransaction != pendingTransactions_.end()) {
-      pendingTransaction->mergeWith(std::move(*mountingTransaction));
-    } else {
-      pendingTransactions_.push_back(std::move(*mountingTransaction));
-    }
-  }
+    const std::shared_ptr<const MountingCoordinator>& /*mountingCoordinator*/) {
+  // We don't do anything here. We will pull the transaction in
+  // `schedulerShouldRenderTransactions`.
 }
 
 void FabricUIManagerBinding::schedulerShouldRenderTransactions(
@@ -671,33 +645,11 @@ void FabricUIManagerBinding::schedulerShouldRenderTransactions(
     }
   }
 
-  if (ReactNativeFeatureFlags::enableAccumulatedUpdatesInRawPropsAndroid()) {
-    auto mountingTransaction = mountingCoordinator->pullTransaction(
-        /* willPerformAsynchronously = */ true);
-    if (mountingTransaction.has_value()) {
-      auto transaction = std::move(*mountingTransaction);
-      mountingManager->executeMount(transaction);
-    }
-  } else {
-    std::vector<MountingTransaction> pendingTransactions;
-
-    {
-      // Retain the lock to access the pending transactions but not to execute
-      // the mount operations because that method can call into this method
-      // again.
-      //
-      // This can be re-entrant when mounting manager triggers state updates
-      // synchronously (this can happen when committing from the UI thread).
-      // This is safe because we're already combining all the transactions for
-      // the same surface ID in a single transaction in the pending transactions
-      // list, so operations won't run out of order.
-      std::unique_lock<std::mutex> lock(pendingTransactionsMutex_);
-      pendingTransactions_.swap(pendingTransactions);
-    }
-
-    for (auto& transaction : pendingTransactions) {
-      mountingManager->executeMount(transaction);
-    }
+  auto mountingTransaction = mountingCoordinator->pullTransaction(
+      /* willPerformAsynchronously = */ true);
+  if (mountingTransaction.has_value()) {
+    auto transaction = std::move(*mountingTransaction);
+    mountingManager->executeMount(transaction);
   }
 }
 

packages/react-native/ReactAndroid/src/main/jni/react/fabric/FabricUIManagerBinding.h

@@ -159,10 +159,6 @@ class FabricUIManagerBinding : public jni::HybridClass<FabricUIManagerBinding>,
       surfaceHandlerRegistry_{};
   std::shared_mutex surfaceHandlerRegistryMutex_; // Protects `surfaceHandlerRegistry_`.
 
-  // Track pending transactions, one per surfaceId
-  std::mutex pendingTransactionsMutex_;
-  std::vector<MountingTransaction> pendingTransactions_;
-
   float pointScaleFactor_ = 1;
 
   bool enableFabricLogs_{false};

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp

@@ -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<<411aef7b1b977407b52e4f23e95db0a5>>
+ * @generated SignedSource<<4b634360db1cb90223867041ea754fdc>>
  */
 
 /**
@@ -105,12 +105,6 @@ class ReactNativeFeatureFlagsJavaProvider
     return method(javaProvider_);
   }
 
-  bool enableAccumulatedUpdatesInRawPropsAndroid() override {
-    static const auto method =
-        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("enableAccumulatedUpdatesInRawPropsAndroid");
-    return method(javaProvider_);
-  }
-
   bool enableAndroidTextMeasurementOptimizations() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("enableAndroidTextMeasurementOptimizations");
@@ -650,11 +644,6 @@ bool JReactNativeFeatureFlagsCxxInterop::enableAccessibilityOrder(
   return ReactNativeFeatureFlags::enableAccessibilityOrder();
 }
 
-bool JReactNativeFeatureFlagsCxxInterop::enableAccumulatedUpdatesInRawPropsAndroid(
-    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
-  return ReactNativeFeatureFlags::enableAccumulatedUpdatesInRawPropsAndroid();
-}
-
 bool JReactNativeFeatureFlagsCxxInterop::enableAndroidTextMeasurementOptimizations(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::enableAndroidTextMeasurementOptimizations();
@@ -1119,9 +1108,6 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "enableAccessibilityOrder",
         JReactNativeFeatureFlagsCxxInterop::enableAccessibilityOrder),
-      makeNativeMethod(
-        "enableAccumulatedUpdatesInRawPropsAndroid",
-        JReactNativeFeatureFlagsCxxInterop::enableAccumulatedUpdatesInRawPropsAndroid),
       makeNativeMethod(
         "enableAndroidTextMeasurementOptimizations",
         JReactNativeFeatureFlagsCxxInterop::enableAndroidTextMeasurementOptimizations),