Send only changed props on Insert of preallocated views with accumulated raw props

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<<a39494512e761e266940e5d1853f38fc>>
+ * @generated SignedSource<<86390dbd6b2c57cb4f8cdd7cb73cc1f7>>
  */
 
 /**
@@ -300,6 +300,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun enableNativeCSSParsing(): Boolean = accessor.enableNativeCSSParsing()
 
+  /**
+   * When enabled together with `enableAccumulatedUpdatesInRawPropsAndroid`, the Insert of a preallocated view only sends the difference between the props the view was preallocated with and the inserted props, instead of sending all props again on every Insert.
+   */
+  @JvmStatic
+  public fun enablePreallocatedPropsDiffOnInsertAndroid(): Boolean = accessor.enablePreallocatedPropsDiffOnInsertAndroid()
+
   /**
    * Enables caching text layout artifacts for later reuse
    */

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<<cd1753241fa2f51c23cd4e01ffe3f18c>>
+ * @generated SignedSource<<3e939eebe846d12cab15905db8efba18>>
  */
 
 /**
@@ -65,6 +65,7 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
   private var enableMountingCoordinatorPullModelAndroidCache: Boolean? = null
   private var enableMutationObserverByDefaultCache: Boolean? = null
   private var enableNativeCSSParsingCache: Boolean? = null
+  private var enablePreallocatedPropsDiffOnInsertAndroidCache: Boolean? = null
   private var enablePreparedTextLayoutCache: Boolean? = null
   private var enablePropsUpdateReconciliationAndroidCache: Boolean? = null
   private var enableResizeObserverByDefaultCache: Boolean? = null
@@ -515,6 +516,15 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun enablePreallocatedPropsDiffOnInsertAndroid(): Boolean {
+    var cached = enablePreallocatedPropsDiffOnInsertAndroidCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.enablePreallocatedPropsDiffOnInsertAndroid()
+      enablePreallocatedPropsDiffOnInsertAndroidCache = cached
+    }
+    return cached
+  }
+
   override fun enablePreparedTextLayout(): Boolean {
     var cached = enablePreparedTextLayoutCache
     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<<eb8737673aaec0b1eda6ae2ebc0b9970>>
+ * @generated SignedSource<<da34d40665437b2901de2ca5f0bee7c1>>
  */
 
 /**
@@ -118,6 +118,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun enableNativeCSSParsing(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun enablePreallocatedPropsDiffOnInsertAndroid(): Boolean
+
   @DoNotStrip @JvmStatic public external fun enablePreparedTextLayout(): Boolean
 
   @DoNotStrip @JvmStatic public external fun enablePropsUpdateReconciliationAndroid(): 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<<890e204b6cf8afef481f64de44766edf>>
+ * @generated SignedSource<<0f4c074c11c564f05950eab73a8fd452>>
  */
 
 /**
@@ -113,6 +113,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun enableNativeCSSParsing(): Boolean = false
 
+  override fun enablePreallocatedPropsDiffOnInsertAndroid(): Boolean = false
+
   override fun enablePreparedTextLayout(): Boolean = false
 
   override fun enablePropsUpdateReconciliationAndroid(): 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<<9044f0df865ba9d7668f9ff391d21911>>
+ * @generated SignedSource<<013790bd2c3fa8b9ff03e8c5e924bf91>>
  */
 
 /**
@@ -69,6 +69,7 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
   private var enableMountingCoordinatorPullModelAndroidCache: Boolean? = null
   private var enableMutationObserverByDefaultCache: Boolean? = null
   private var enableNativeCSSParsingCache: Boolean? = null
+  private var enablePreallocatedPropsDiffOnInsertAndroidCache: Boolean? = null
   private var enablePreparedTextLayoutCache: Boolean? = null
   private var enablePropsUpdateReconciliationAndroidCache: Boolean? = null
   private var enableResizeObserverByDefaultCache: Boolean? = null
@@ -564,6 +565,16 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
     return cached
   }
 
+  override fun enablePreallocatedPropsDiffOnInsertAndroid(): Boolean {
+    var cached = enablePreallocatedPropsDiffOnInsertAndroidCache
+    if (cached == null) {
+      cached = currentProvider.enablePreallocatedPropsDiffOnInsertAndroid()
+      accessedFeatureFlags.add("enablePreallocatedPropsDiffOnInsertAndroid")
+      enablePreallocatedPropsDiffOnInsertAndroidCache = cached
+    }
+    return cached
+  }
+
   override fun enablePreparedTextLayout(): Boolean {
     var cached = enablePreparedTextLayoutCache
     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<<cfd99e53a077549124370e6bb123ba43>>
+ * @generated SignedSource<<6607c8678df2693c361f6d8091483662>>
  */
 
 /**
@@ -113,6 +113,8 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun enableNativeCSSParsing(): Boolean
 
+  @DoNotStrip public fun enablePreallocatedPropsDiffOnInsertAndroid(): Boolean
+
   @DoNotStrip public fun enablePreparedTextLayout(): Boolean
 
   @DoNotStrip public fun enablePropsUpdateReconciliationAndroid(): Boolean

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

@@ -46,7 +46,7 @@ FabricMountingManager::~FabricMountingManager() {
 void FabricMountingManager::onSurfaceStart(SurfaceId surfaceId) {
   std::lock_guard lock(allocatedViewsMutex_);
   allocatedViewRegistry_.emplace(
-      surfaceId, std::unordered_set<Tag>({surfaceId}));
+      surfaceId, std::unordered_map<Tag, Props::Shared>{{surfaceId, nullptr}});
 }
 
 void FabricMountingManager::onSurfaceStop(SurfaceId surfaceId) {
@@ -311,6 +311,11 @@ inline float scale(Float value, Float pointScaleFactor) {
   return result;
 }
 
+bool shouldDiffInsertPropsAgainstPreallocatedProps() {
+  return ReactNativeFeatureFlags::enableAccumulatedUpdatesInRawPropsAndroid() &&
+      ReactNativeFeatureFlags::enablePreallocatedPropsDiffOnInsertAndroid();
+}
+
 jni::local_ref<jobject> getProps(
     const ShadowView& oldShadowView,
     const ShadowView& newShadowView) {
@@ -609,12 +614,12 @@ void FabricMountingManager::executeMount(
     std::lock_guard allocatedViewsLock(allocatedViewsMutex_);
 
     auto allocatedViewsIterator = allocatedViewRegistry_.find(surfaceId);
-    auto defaultAllocatedViews = std::unordered_set<Tag>{};
+    auto defaultAllocatedViews = std::unordered_map<Tag, Props::Shared>{};
     // Do not remove `defaultAllocatedViews` or initialize
-    // `std::unordered_set<Tag>{}` inline in below ternary expression - if falsy
-    // operand is a value type, the compiler will decide the expression to be a
-    // value type, an unnecessary (sometimes expensive) copy will happen as a
-    // result.
+    // `std::unordered_map<Tag, Props::Shared>{}` inline in below ternary
+    // expression - if falsy operand is a value type, the compiler will decide
+    // the expression to be a value type, an unnecessary (sometimes expensive)
+    // copy will happen as a result.
     auto& allocatedViewTags =
         allocatedViewsIterator != allocatedViewRegistry_.end()
         ? allocatedViewsIterator->second
@@ -640,7 +645,7 @@ void FabricMountingManager::executeMount(
           if (shouldCreateView) {
             cppCommonMountItems.push_back(
                 CppMountItem::CreateMountItem(newChildShadowView));
-            allocatedViewTags.insert(newChildShadowView.tag);
+            allocatedViewTags.emplace(newChildShadowView.tag, nullptr);
           }
           break;
         }
@@ -734,19 +739,34 @@ void FabricMountingManager::executeMount(
                 CppMountItem::InsertMountItem(
                     parentTag, newChildShadowView, index));
 
-            bool shouldCreateView =
-                !allocatedViewTags.contains(newChildShadowView.tag);
+            auto allocatedView = allocatedViewTags.find(newChildShadowView.tag);
+            bool shouldCreateView = allocatedView == allocatedViewTags.end();
             if (ReactNativeFeatureFlags::
                     enableAccumulatedUpdatesInRawPropsAndroid()) {
               if (shouldCreateView) {
                 LOG(ERROR) << "Emitting insert for unallocated view "
                            << newChildShadowView.tag;
               }
-              (maintainMutationOrder ? cppCommonMountItems
-                                     : cppUpdatePropsMountItems)
-                  .push_back(
-                      CppMountItem::UpdatePropsMountItem(
-                          {}, newChildShadowView));
+              if (shouldCreateView ||
+                  !shouldDiffInsertPropsAgainstPreallocatedProps()) {
+                (maintainMutationOrder ? cppCommonMountItems
+                                       : cppUpdatePropsMountItems)
+                    .push_back(
+                        CppMountItem::UpdatePropsMountItem(
+                            {}, newChildShadowView));
+              } else if (auto& preallocatedProps = allocatedView->second;
+                         preallocatedProps != nullptr) {
+                if (preallocatedProps != newChildShadowView.props) {
+                  auto preallocatedShadowView = newChildShadowView;
+                  preallocatedShadowView.props = preallocatedProps;
+                  (maintainMutationOrder ? cppCommonMountItems
+                                         : cppUpdatePropsMountItems)
+                      .push_back(
+                          CppMountItem::UpdatePropsMountItem(
+                              preallocatedShadowView, newChildShadowView));
+                }
+                preallocatedProps = nullptr;
+              }
             } else {
               if (shouldCreateView) {
                 LOG(ERROR) << "Emitting insert for unallocated view "
@@ -1107,8 +1127,10 @@ void FabricMountingManager::preallocateShadowView(
     if (allocatedViewsIterator == allocatedViewRegistry_.end()) {
       return;
     }
-    const auto [_, inserted] =
-        allocatedViewsIterator->second.insert(shadowView.tag);
+    const auto [_, inserted] = allocatedViewsIterator->second.emplace(
+        shadowView.tag,
+        shouldDiffInsertPropsAgainstPreallocatedProps() ? shadowView.props
+                                                        : nullptr);
     if (!inserted) {
       return;
     }

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

@@ -9,10 +9,10 @@
 
 #include <mutex>
 #include <unordered_map>
-#include <unordered_set>
 
 #include <fbjni/fbjni.h>
 #include <react/fabric/JFabricUIManager.h>
+#include <react/renderer/core/Props.h>
 #include <react/renderer/uimanager/primitives.h>
 
 namespace facebook::react {
@@ -109,7 +109,12 @@ class FabricMountingManager final {
    */
   std::vector<ShadowView> preallocatedViewsQueue_{};
 
-  std::unordered_map<SurfaceId, std::unordered_set<Tag>> allocatedViewRegistry_{};
+  /*
+   * Allocated tags per surface. With enablePreallocatedPropsDiffOnInsertAndroid
+   * a preallocated tag maps to the props it was preallocated with until its
+   * first Insert; every other tag maps to nullptr.
+   */
+  std::unordered_map<SurfaceId, std::unordered_map<Tag, Props::Shared>> allocatedViewRegistry_{};
   std::recursive_mutex allocatedViewsMutex_;
 };
 

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<<e6f56d60147d5c08e0b38549b9956e52>>
+ * @generated SignedSource<<dad8d48d93f01fc5ec68f70dbd9a9e73>>
  */
 
 /**
@@ -309,6 +309,12 @@ class ReactNativeFeatureFlagsJavaProvider
     return method(javaProvider_);
   }
 
+  bool enablePreallocatedPropsDiffOnInsertAndroid() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("enablePreallocatedPropsDiffOnInsertAndroid");
+    return method(javaProvider_);
+  }
+
   bool enablePreparedTextLayout() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("enablePreparedTextLayout");
@@ -802,6 +808,11 @@ bool JReactNativeFeatureFlagsCxxInterop::enableNativeCSSParsing(
   return ReactNativeFeatureFlags::enableNativeCSSParsing();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::enablePreallocatedPropsDiffOnInsertAndroid(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::enablePreallocatedPropsDiffOnInsertAndroid();
+}
+
 bool JReactNativeFeatureFlagsCxxInterop::enablePreparedTextLayout(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::enablePreparedTextLayout();
@@ -1188,6 +1199,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "enableNativeCSSParsing",
         JReactNativeFeatureFlagsCxxInterop::enableNativeCSSParsing),
+      makeNativeMethod(
+        "enablePreallocatedPropsDiffOnInsertAndroid",
+        JReactNativeFeatureFlagsCxxInterop::enablePreallocatedPropsDiffOnInsertAndroid),
       makeNativeMethod(
         "enablePreparedTextLayout",
         JReactNativeFeatureFlagsCxxInterop::enablePreparedTextLayout),

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<<25d66101785e737822e86d218789912d>>
+ * @generated SignedSource<<7a9a9c1938c3e01f589e05fffe349ad3>>
  */
 
 /**
@@ -165,6 +165,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool enableNativeCSSParsing(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool enablePreallocatedPropsDiffOnInsertAndroid(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static bool enablePreparedTextLayout(
     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<<8b8b80ac3744a205b20cfd0627856fba>>
+ * @generated SignedSource<<8b23b6ea5f2d377f8126adffd753dae7>>
  */
 
 /**
@@ -206,6 +206,10 @@ bool ReactNativeFeatureFlags::enableNativeCSSParsing() {
   return getAccessor().enableNativeCSSParsing();
 }
 
+bool ReactNativeFeatureFlags::enablePreallocatedPropsDiffOnInsertAndroid() {
+  return getAccessor().enablePreallocatedPropsDiffOnInsertAndroid();
+}
+
 bool ReactNativeFeatureFlags::enablePreparedTextLayout() {
   return getAccessor().enablePreparedTextLayout();
 }

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<<4c93a39dd2a8ee5ba24f3f8bc99ac1ae>>
+ * @generated SignedSource<<aef7d6ac25fdeb2423ebf4a2a9ac6f2e>>
  */
 
 /**
@@ -266,6 +266,11 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool enableNativeCSSParsing();
 
+  /**
+   * When enabled together with `enableAccumulatedUpdatesInRawPropsAndroid`, the Insert of a preallocated view only sends the difference between the props the view was preallocated with and the inserted props, instead of sending all props again on every Insert.
+   */
+  RN_EXPORT static bool enablePreallocatedPropsDiffOnInsertAndroid();
+
   /**
    * Enables caching text layout artifacts for later reuse
    */