Pre-allocate mutation vectors in Differentiator to reduce reallocation overhead

Summary:
Changelog: [Internal]

speed up differentiator

| Test                          | Before (ms) | After (ms) | Improvement |
|-------------------------------|-------------|------------|-------------|
| 100 uncollapsable views       | 3.0         | 2.7        | +10%        |
| 1000 uncollapsable views      | 91.1        | 50.5       | +45%        |
| 100 views w/ many props       | 9.8         | 9.2        | +6%         |
| 1000 views w/ many props      | 147.4       | 116.7      | +21%        |
| 1500 views w/ many props      | 143.1       | 136.7      | +5%         |

Differential Revision: D94096006

Author: sammy-SC

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<<477777b9a795b57f3bb3eaeb030738a9>>
+ * @generated SignedSource<<22cf2dd60587b906939f2774d416f035>>
  */
 
 /**
@@ -138,6 +138,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun enableCustomFocusSearchOnClippedElementsAndroid(): Boolean = accessor.enableCustomFocusSearchOnClippedElementsAndroid()
 
+  /**
+   * Pre-allocate mutation vectors in the Differentiator to reduce reallocation overhead during shadow view diffing.
+   */
+  @JvmStatic
+  public fun enableDifferentiatorMutationVectorPreallocation(): Boolean = accessor.enableDifferentiatorMutationVectorPreallocation()
+
   /**
    * Enables destructor calls for ShadowTreeRevision in the background to reduce UI thread work.
    */

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<<c7b6ea7f1672df7bb3396375378784c5>>
+ * @generated SignedSource<<7af3aa99f498c613b30359a17b5577eb>>
  */
 
 /**
@@ -38,6 +38,7 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
   private var enableBridgelessArchitectureCache: Boolean? = null
   private var enableCppPropsIteratorSetterCache: Boolean? = null
   private var enableCustomFocusSearchOnClippedElementsAndroidCache: Boolean? = null
+  private var enableDifferentiatorMutationVectorPreallocationCache: Boolean? = null
   private var enableDestroyShadowTreeRevisionAsyncCache: Boolean? = null
   private var enableDoubleMeasurementFixAndroidCache: Boolean? = null
   private var enableEagerMainQueueModulesOnIOSCache: Boolean? = null
@@ -267,6 +268,15 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun enableDifferentiatorMutationVectorPreallocation(): Boolean {
+    var cached = enableDifferentiatorMutationVectorPreallocationCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.enableDifferentiatorMutationVectorPreallocation()
+      enableDifferentiatorMutationVectorPreallocationCache = cached
+    }
+    return cached
+  }
+
   override fun enableDestroyShadowTreeRevisionAsync(): Boolean {
     var cached = enableDestroyShadowTreeRevisionAsyncCache
     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<<ec036cff49622b8c2b52d2f9eaa59e6c>>
+ * @generated SignedSource<<8b47d3a231a37a3d4a7b89a74a5a0122>>
  */
 
 /**
@@ -64,6 +64,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun enableCustomFocusSearchOnClippedElementsAndroid(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun enableDifferentiatorMutationVectorPreallocation(): Boolean
+
   @DoNotStrip @JvmStatic public external fun enableDestroyShadowTreeRevisionAsync(): Boolean
 
   @DoNotStrip @JvmStatic public external fun enableDoubleMeasurementFixAndroid(): 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<<523e3c35d4bd1fc85f2a3bb26b8aad3f>>
+ * @generated SignedSource<<54932f95b0a9cf0483a2bc03b3d3cc74>>
  */
 
 /**
@@ -59,6 +59,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun enableCustomFocusSearchOnClippedElementsAndroid(): Boolean = true
 
+  override fun enableDifferentiatorMutationVectorPreallocation(): Boolean = false
+
   override fun enableDestroyShadowTreeRevisionAsync(): Boolean = false
 
   override fun enableDoubleMeasurementFixAndroid(): 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<<cfd6a4514be320519a57566182b73f69>>
+ * @generated SignedSource<<70a43edd653ba85c3885af1e13e9fb95>>
  */
 
 /**
@@ -42,6 +42,7 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
   private var enableBridgelessArchitectureCache: Boolean? = null
   private var enableCppPropsIteratorSetterCache: Boolean? = null
   private var enableCustomFocusSearchOnClippedElementsAndroidCache: Boolean? = null
+  private var enableDifferentiatorMutationVectorPreallocationCache: Boolean? = null
   private var enableDestroyShadowTreeRevisionAsyncCache: Boolean? = null
   private var enableDoubleMeasurementFixAndroidCache: Boolean? = null
   private var enableEagerMainQueueModulesOnIOSCache: Boolean? = null
@@ -289,6 +290,16 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
     return cached
   }
 
+  override fun enableDifferentiatorMutationVectorPreallocation(): Boolean {
+    var cached = enableDifferentiatorMutationVectorPreallocationCache
+    if (cached == null) {
+      cached = currentProvider.enableDifferentiatorMutationVectorPreallocation()
+      accessedFeatureFlags.add("enableDifferentiatorMutationVectorPreallocation")
+      enableDifferentiatorMutationVectorPreallocationCache = cached
+    }
+    return cached
+  }
+
   override fun enableDestroyShadowTreeRevisionAsync(): Boolean {
     var cached = enableDestroyShadowTreeRevisionAsyncCache
     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<<bbaa4d1498f606886341d34a62acb508>>
+ * @generated SignedSource<<6a40e5cbecff645336f690a95d1684fd>>
  */
 
 /**
@@ -59,6 +59,8 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun enableCustomFocusSearchOnClippedElementsAndroid(): Boolean
 
+  @DoNotStrip public fun enableDifferentiatorMutationVectorPreallocation(): Boolean
+
   @DoNotStrip public fun enableDestroyShadowTreeRevisionAsync(): Boolean
 
   @DoNotStrip public fun enableDoubleMeasurementFixAndroid(): 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<<45063df01d7ce8726b4a7d901f1b3341>>
+ * @generated SignedSource<<736f0da032f0d0e61e88a2268b071716>>
  */
 
 /**
@@ -147,6 +147,12 @@ class ReactNativeFeatureFlagsJavaProvider
     return method(javaProvider_);
   }
 
+  bool enableDifferentiatorMutationVectorPreallocation() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("enableDifferentiatorMutationVectorPreallocation");
+    return method(javaProvider_);
+  }
+
   bool enableDestroyShadowTreeRevisionAsync() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("enableDestroyShadowTreeRevisionAsync");
@@ -637,6 +643,11 @@ bool JReactNativeFeatureFlagsCxxInterop::enableCustomFocusSearchOnClippedElement
   return ReactNativeFeatureFlags::enableCustomFocusSearchOnClippedElementsAndroid();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::enableDifferentiatorMutationVectorPreallocation(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::enableDifferentiatorMutationVectorPreallocation();
+}
+
 bool JReactNativeFeatureFlagsCxxInterop::enableDestroyShadowTreeRevisionAsync(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::enableDestroyShadowTreeRevisionAsync();
@@ -1052,6 +1063,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "enableCustomFocusSearchOnClippedElementsAndroid",
         JReactNativeFeatureFlagsCxxInterop::enableCustomFocusSearchOnClippedElementsAndroid),
+      makeNativeMethod(
+        "enableDifferentiatorMutationVectorPreallocation",
+        JReactNativeFeatureFlagsCxxInterop::enableDifferentiatorMutationVectorPreallocation),
       makeNativeMethod(
         "enableDestroyShadowTreeRevisionAsync",
         JReactNativeFeatureFlagsCxxInterop::enableDestroyShadowTreeRevisionAsync),

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<<5ac93ed057017f8d1a388b8029614f18>>
+ * @generated SignedSource<<ca1ca3ebd21aca34c80512e829027dc9>>
  */
 
 /**
@@ -84,6 +84,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool enableCustomFocusSearchOnClippedElementsAndroid(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool enableDifferentiatorMutationVectorPreallocation(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static bool enableDestroyShadowTreeRevisionAsync(
     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<<9d81f74c5926706ee353813e594575e8>>
+ * @generated SignedSource<<89d14fa7c51ca92ab1c42f5bc1e18bae>>
  */
 
 /**
@@ -98,6 +98,10 @@ bool ReactNativeFeatureFlags::enableCustomFocusSearchOnClippedElementsAndroid()
   return getAccessor().enableCustomFocusSearchOnClippedElementsAndroid();
 }
 
+bool ReactNativeFeatureFlags::enableDifferentiatorMutationVectorPreallocation() {
+  return getAccessor().enableDifferentiatorMutationVectorPreallocation();
+}
+
 bool ReactNativeFeatureFlags::enableDestroyShadowTreeRevisionAsync() {
   return getAccessor().enableDestroyShadowTreeRevisionAsync();
 }

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<<84e2800073ffab2313a4e27897c0c246>>
+ * @generated SignedSource<<97f4abf7e573a97e54b3e9c2473226ec>>
  */
 
 /**
@@ -129,6 +129,11 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool enableCustomFocusSearchOnClippedElementsAndroid();
 
+  /**
+   * Pre-allocate mutation vectors in the Differentiator to reduce reallocation overhead during shadow view diffing.
+   */
+  RN_EXPORT static bool enableDifferentiatorMutationVectorPreallocation();
+
   /**
    * Enables destructor calls for ShadowTreeRevision in the background to reduce UI thread work.
    */