Introduce enableFabricCommitBranchingMergeOnMainThread feature flag (#58614)

Summary:
Pull Request resolved: #58614

Changelog: [Internal]

Adds `enableFabricCommitBranchingMergeOnMainThread` feature flag for follow-up diffs.

Reviewed By: javache

Differential Revision: D120981615

fbshipit-source-id: 2294f6bee061eebc01702e0224c95d0e2c625705

Author: j-piasecki

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<<7d7547b5f25dbe0d0e6722d2f2bf5baf>>
+ * @generated SignedSource<<a5c748863dbb09c323056ca1ec17774b>>
  */
 
 /**
@@ -163,11 +163,17 @@ public object ReactNativeFeatureFlags {
   public fun enableExclusivePropsUpdateAndroid(): Boolean = accessor.enableExclusivePropsUpdateAndroid()
 
   /**
-   * Enables Fabric commit branching to fix starvation problems and atomic JS updates.
+   * Enables Fabric commit branching to fix atomic JS updates.
    */
   @JvmStatic
   public fun enableFabricCommitBranching(): Boolean = accessor.enableFabricCommitBranching()
 
+  /**
+   * Enables Fabric commit branching merge to happen on the main thread to fix starvation problems.
+   */
+  @JvmStatic
+  public fun enableFabricCommitBranchingMergeOnMainThread(): Boolean = accessor.enableFabricCommitBranchingMergeOnMainThread()
+
   /**
    * This feature flag enables logs for Fabric.
    */

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<<c07cb2f4489ba94f267d0c76616ee718>>
+ * @generated SignedSource<<e69290c5801d6f796d368c643f9e8072>>
  */
 
 /**
@@ -43,6 +43,7 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
   private var enableEagerRootViewAttachmentCache: Boolean? = null
   private var enableExclusivePropsUpdateAndroidCache: Boolean? = null
   private var enableFabricCommitBranchingCache: Boolean? = null
+  private var enableFabricCommitBranchingMergeOnMainThreadCache: Boolean? = null
   private var enableFabricLogsCache: Boolean? = null
   private var enableFlexboxAutoMinSizeInStrictModeCache: Boolean? = null
   private var enableFontScaleChangesUpdatingLayoutCache: Boolean? = null
@@ -316,6 +317,15 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun enableFabricCommitBranchingMergeOnMainThread(): Boolean {
+    var cached = enableFabricCommitBranchingMergeOnMainThreadCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.enableFabricCommitBranchingMergeOnMainThread()
+      enableFabricCommitBranchingMergeOnMainThreadCache = cached
+    }
+    return cached
+  }
+
   override fun enableFabricLogs(): Boolean {
     var cached = enableFabricLogsCache
     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<<7d6ce76213f08ecb356fa68e77edfe84>>
+ * @generated SignedSource<<b56cf5b92dffb93e08b3f89668b7eb90>>
  */
 
 /**
@@ -74,6 +74,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun enableFabricCommitBranching(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun enableFabricCommitBranchingMergeOnMainThread(): Boolean
+
   @DoNotStrip @JvmStatic public external fun enableFabricLogs(): Boolean
 
   @DoNotStrip @JvmStatic public external fun enableFlexboxAutoMinSizeInStrictMode(): 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<<0c228a0f53ced43d6744551a92d0ed86>>
+ * @generated SignedSource<<763e4b3cc142f1d34e7ce656ede0cb96>>
  */
 
 /**
@@ -69,6 +69,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun enableFabricCommitBranching(): Boolean = false
 
+  override fun enableFabricCommitBranchingMergeOnMainThread(): Boolean = false
+
   override fun enableFabricLogs(): Boolean = false
 
   override fun enableFlexboxAutoMinSizeInStrictMode(): 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<<37c9d46dfd98d868601390a9262f8d5a>>
+ * @generated SignedSource<<50bc14130889050ec9d447626454fe58>>
  */
 
 /**
@@ -47,6 +47,7 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
   private var enableEagerRootViewAttachmentCache: Boolean? = null
   private var enableExclusivePropsUpdateAndroidCache: Boolean? = null
   private var enableFabricCommitBranchingCache: Boolean? = null
+  private var enableFabricCommitBranchingMergeOnMainThreadCache: Boolean? = null
   private var enableFabricLogsCache: Boolean? = null
   private var enableFlexboxAutoMinSizeInStrictModeCache: Boolean? = null
   private var enableFontScaleChangesUpdatingLayoutCache: Boolean? = null
@@ -343,6 +344,16 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
     return cached
   }
 
+  override fun enableFabricCommitBranchingMergeOnMainThread(): Boolean {
+    var cached = enableFabricCommitBranchingMergeOnMainThreadCache
+    if (cached == null) {
+      cached = currentProvider.enableFabricCommitBranchingMergeOnMainThread()
+      accessedFeatureFlags.add("enableFabricCommitBranchingMergeOnMainThread")
+      enableFabricCommitBranchingMergeOnMainThreadCache = cached
+    }
+    return cached
+  }
+
   override fun enableFabricLogs(): Boolean {
     var cached = enableFabricLogsCache
     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<<18ffa42c9d28304df99548a350b014ac>>
+ * @generated SignedSource<<a9eed3dc15b11bd5708439de0dc46cf9>>
  */
 
 /**
@@ -69,6 +69,8 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun enableFabricCommitBranching(): Boolean
 
+  @DoNotStrip public fun enableFabricCommitBranchingMergeOnMainThread(): Boolean
+
   @DoNotStrip public fun enableFabricLogs(): Boolean
 
   @DoNotStrip public fun enableFlexboxAutoMinSizeInStrictMode(): Boolean

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<<ebc2ba98faa638c89c86c45d35e93c3d>>
+ * @generated SignedSource<<faf56e666f2f0aab01e17fa7d6e186c0>>
  */
 
 /**
@@ -177,6 +177,12 @@ class ReactNativeFeatureFlagsJavaProvider
     return method(javaProvider_);
   }
 
+  bool enableFabricCommitBranchingMergeOnMainThread() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("enableFabricCommitBranchingMergeOnMainThread");
+    return method(javaProvider_);
+  }
+
   bool enableFabricLogs() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("enableFabricLogs");
@@ -686,6 +692,11 @@ bool JReactNativeFeatureFlagsCxxInterop::enableFabricCommitBranching(
   return ReactNativeFeatureFlags::enableFabricCommitBranching();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::enableFabricCommitBranchingMergeOnMainThread(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::enableFabricCommitBranchingMergeOnMainThread();
+}
+
 bool JReactNativeFeatureFlagsCxxInterop::enableFabricLogs(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::enableFabricLogs();
@@ -1111,6 +1122,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "enableFabricCommitBranching",
         JReactNativeFeatureFlagsCxxInterop::enableFabricCommitBranching),
+      makeNativeMethod(
+        "enableFabricCommitBranchingMergeOnMainThread",
+        JReactNativeFeatureFlagsCxxInterop::enableFabricCommitBranchingMergeOnMainThread),
       makeNativeMethod(
         "enableFabricLogs",
         JReactNativeFeatureFlagsCxxInterop::enableFabricLogs),

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

@@ -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<<a19681d4edcac5523ea8978c2fbc52ab>>
+ * @generated SignedSource<<006f29ff357deddc058c69c31528db83>>
  */
 
 /**
@@ -99,6 +99,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool enableFabricCommitBranching(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool enableFabricCommitBranchingMergeOnMainThread(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static bool enableFabricLogs(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.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<<37ceecaa4ef7ce8b076a46652b6cf0f0>>
+ * @generated SignedSource<<d61dace8faf4a80d6babbcd72bdbbde9>>
  */
 
 /**
@@ -118,6 +118,10 @@ bool ReactNativeFeatureFlags::enableFabricCommitBranching() {
   return getAccessor().enableFabricCommitBranching();
 }
 
+bool ReactNativeFeatureFlags::enableFabricCommitBranchingMergeOnMainThread() {
+  return getAccessor().enableFabricCommitBranchingMergeOnMainThread();
+}
+
 bool ReactNativeFeatureFlags::enableFabricLogs() {
   return getAccessor().enableFabricLogs();
 }

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h

@@ -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<<d3937c47ffa5234a2b7632aa92387ee3>>
+ * @generated SignedSource<<7f1f0374fb5e2ec1b2727d1d2a7fc304>>
  */
 
 /**
@@ -152,10 +152,15 @@ class ReactNativeFeatureFlags {
   RN_EXPORT static bool enableExclusivePropsUpdateAndroid();
 
   /**
-   * Enables Fabric commit branching to fix starvation problems and atomic JS updates.
+   * Enables Fabric commit branching to fix atomic JS updates.
    */
   RN_EXPORT static bool enableFabricCommitBranching();
 
+  /**
+   * Enables Fabric commit branching merge to happen on the main thread to fix starvation problems.
+   */
+  RN_EXPORT static bool enableFabricCommitBranchingMergeOnMainThread();
+
   /**
    * This feature flag enables logs for Fabric.
    */