Use mapbuffer for ReactViewGroup

Summary:
Provides an alternative way of diffing props on Android side. Instead of passing dynamic JSON values from JS, the new approach diff C++ props and serializes difference into a `MapBuffer`. Current implementation does this only for `RCTView` component to test performance, correctness and memory impact (as MapBuffers are supposed to be more compact and performant).

This way of passing props allows for additional alignment between platforms, as C++ props are now source of truth for the view state, similar to iOS. At the same time, changing serialization method requires reimplementing `ViewManager` codegen (done manually for now) to account for `MapBuffer`s.

Changelog: [Added][Android] - Added an experimental prop serialization path based on MapBuffer

Reviewed By: mdvacca

Differential Revision: D33735245

fbshipit-source-id: 1515b5fe92f6557ae55abe215ce48277c83974a6

Author: Andrei Shikov

ReactAndroid/src/main/java/com/facebook/react/bridge/JavaOnlyMap.java

@@ -31,6 +31,10 @@ public static JavaOnlyMap of(Object... keysAndValues) {
     return new JavaOnlyMap(keysAndValues);
   }
 
+  public static JavaOnlyMap from(Map<String, Object> map) {
+    return new JavaOnlyMap(map);
+  }
+
   public static JavaOnlyMap deepClone(ReadableMap map) {
     JavaOnlyMap res = new JavaOnlyMap();
     ReadableMapKeySetIterator iter = map.keySetIterator();

ReactAndroid/src/main/java/com/facebook/react/common/mapbuffer/ReadableMapBuffer.java

@@ -301,6 +301,36 @@ public boolean equals(@Nullable Object obj) {
     return thisByteBuffer.equals(otherByteBuffer);
   }
 
+  @Override
+  public String toString() {
+    StringBuilder builder = new StringBuilder("{");
+    for (MapBufferEntry entry : this) {
+      int key = entry.getKey();
+      builder.append(key);
+      builder.append('=');
+      switch (entry.getType()) {
+        case BOOL:
+          builder.append(entry.getBoolean());
+          break;
+        case INT:
+          builder.append(entry.getInt());
+          break;
+        case DOUBLE:
+          builder.append(entry.getDouble());
+          break;
+        case STRING:
+          builder.append(entry.getString());
+          break;
+        case MAP:
+          builder.append(entry.getReadableMapBuffer().toString());
+          break;
+      }
+      builder.append(',');
+    }
+    builder.append('}');
+    return builder.toString();
+  }
+
   /** @return an {@link Iterator<MapBufferEntry>} for the entries of this MapBuffer. */
   @Override
   public Iterator<MapBufferEntry> iterator() {
@@ -372,15 +402,15 @@ public boolean getBoolean() {
     }
 
     /** @return the String value that is stored in this {@link MapBufferEntry}. */
-    public @Nullable String getString() {
+    public String getString() {
       assertType(DataType.STRING);
       return readStringValue(mBucketOffset + VALUE_OFFSET);
     }
 
     /**
      * @return the {@link ReadableMapBuffer} value that is stored in this {@link MapBufferEntry}.
      */
-    public @Nullable ReadableMapBuffer getReadableMapBuffer() {
+    public ReadableMapBuffer getReadableMapBuffer() {
       assertType(DataType.MAP);
       return readMapBufferValue(mBucketOffset + VALUE_OFFSET);
     }

ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java

@@ -704,7 +704,7 @@ private void preallocateView(
       int rootTag,
       int reactTag,
       final String componentName,
-      @Nullable ReadableMap props,
+      @Nullable Object props,
       @Nullable Object stateWrapper,
       @Nullable Object eventEmitterWrapper,
       boolean isLayoutable) {

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/FabricMountItem.cpp

@@ -28,8 +28,11 @@ CppMountItem CppMountItem::RemoveMountItem(
     int index) {
   return {CppMountItem::Type::Remove, parentView, shadowView, {}, index};
 }
-CppMountItem CppMountItem::UpdatePropsMountItem(ShadowView const &shadowView) {
-  return {CppMountItem::Type::UpdateProps, {}, {}, shadowView, -1};
+CppMountItem CppMountItem::UpdatePropsMountItem(
+    ShadowView const &oldShadowView,
+    ShadowView const &newShadowView) {
+  return {
+      CppMountItem::Type::UpdateProps, {}, oldShadowView, newShadowView, -1};
 }
 CppMountItem CppMountItem::UpdateStateMountItem(ShadowView const &shadowView) {
   return {CppMountItem::Type::UpdateState, {}, {}, shadowView, -1};

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/FabricMountItem.h

@@ -35,7 +35,9 @@ struct CppMountItem final {
       ShadowView const &shadowView,
       int index);
 
-  static CppMountItem UpdatePropsMountItem(ShadowView const &shadowView);
+  static CppMountItem UpdatePropsMountItem(
+      ShadowView const &oldShadowView,
+      ShadowView const &newShadowView);
 
   static CppMountItem UpdateStateMountItem(ShadowView const &shadowView);
 

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/FabricMountingManager.cpp

@@ -8,6 +8,7 @@
 #include "FabricMountingManager.h"
 #include "EventEmitterWrapper.h"
 #include "StateWrapperImpl.h"
+#include "viewPropConversions.h"
 
 #include <react/jni/ReadableNativeMap.h>
 #include <react/renderer/components/scrollview/ScrollViewProps.h>
@@ -177,11 +178,6 @@ static inline void writeIntBufferTypePreamble(
   }
 }
 
-inline local_ref<ReadableMap::javaobject> castReadableMap(
-    local_ref<ReadableNativeMap::javaobject> const &nativeMap) {
-  return make_local(reinterpret_cast<ReadableMap::javaobject>(nativeMap.get()));
-}
-
 inline local_ref<ReadableArray::javaobject> castReadableArray(
     local_ref<ReadableNativeArray::javaobject> const &nativeArray) {
   return make_local(
@@ -222,6 +218,22 @@ static inline float scale(Float value, Float pointScaleFactor) {
   return result;
 }
 
+local_ref<jobject> FabricMountingManager::getProps(
+    ShadowView const &oldShadowView,
+    ShadowView const &newShadowView) {
+  if (useMapBufferForViewProps_ &&
+      newShadowView.traits.check(ShadowNodeTraits::Trait::View)) {
+    auto oldProps = oldShadowView.props != nullptr
+        ? static_cast<ViewProps const &>(*oldShadowView.props)
+        : ViewProps{};
+    auto newProps = static_cast<ViewProps const &>(*newShadowView.props);
+    return ReadableMapBuffer::createWithContents(
+        viewPropsDiff(oldProps, newProps));
+  } else {
+    return ReadableNativeMap::newObjectCxxArgs(newShadowView.props->rawProps);
+  }
+}
+
 void FabricMountingManager::executeMount(
     MountingCoordinator::Shared const &mountingCoordinator) {
   std::lock_guard<std::recursive_mutex> lock(commitMutex_);
@@ -308,7 +320,8 @@ void FabricMountingManager::executeMount(
           if (!isVirtual) {
             if (oldChildShadowView.props != newChildShadowView.props) {
               cppUpdatePropsMountItems.push_back(
-                  CppMountItem::UpdatePropsMountItem(newChildShadowView));
+                  CppMountItem::UpdatePropsMountItem(
+                      oldChildShadowView, newChildShadowView));
             }
             if (oldChildShadowView.state != newChildShadowView.state) {
               cppUpdateStateMountItems.push_back(
@@ -367,7 +380,7 @@ void FabricMountingManager::executeMount(
                 shouldRememberAllocatedViews_ ? allocationCheck : revisionCheck;
             if (shouldCreateView) {
               cppUpdatePropsMountItems.push_back(
-                  CppMountItem::UpdatePropsMountItem(newChildShadowView));
+                  CppMountItem::UpdatePropsMountItem({}, newChildShadowView));
             }
 
             // State
@@ -484,7 +497,6 @@ void FabricMountingManager::executeMount(
 
   // Allocate the intBuffer and object array, now that we know exact sizes
   // necessary
-  // TODO: don't allocate at all if size is zero
   jintArray intBufferArray = env->NewIntArray(batchMountItemIntsSize);
   local_ref<JArrayClass<jobject>> objBufferArray =
       JArrayClass<jobject>::newArray(batchMountItemObjectsSize);
@@ -525,10 +537,8 @@ void FabricMountingManager::executeMount(
       int isLayoutable =
           mountItem.newChildShadowView.layoutMetrics != EmptyLayoutMetrics ? 1
                                                                            : 0;
-
-      local_ref<ReadableMap::javaobject> props =
-          castReadableMap(ReadableNativeMap::newObjectCxxArgs(
-              mountItem.newChildShadowView.props->rawProps));
+      local_ref<JObject> props =
+          getProps(mountItem.oldChildShadowView, mountItem.newChildShadowView);
 
       // Do not hold onto Java object from C
       // We DO want to hold onto C object from Java, since we don't know the
@@ -584,11 +594,8 @@ void FabricMountingManager::executeMount(
       temp[0] = mountItem.newChildShadowView.tag;
       env->SetIntArrayRegion(intBufferArray, intBufferPosition, 1, temp);
       intBufferPosition += 1;
-
-      auto newProps = mountItem.newChildShadowView.props->rawProps;
-      local_ref<ReadableMap::javaobject> newPropsReadableMap =
-          castReadableMap(ReadableNativeMap::newObjectCxxArgs(newProps));
-      (*objBufferArray)[objBufferPosition++] = newPropsReadableMap.get();
+      (*objBufferArray)[objBufferPosition++] =
+          getProps(mountItem.oldChildShadowView, mountItem.newChildShadowView);
     }
   }
   if (!cppUpdateStateMountItems.empty()) {
@@ -795,15 +802,11 @@ void FabricMountingManager::preallocateShadowView(
 
   bool isLayoutableShadowNode = shadowView.layoutMetrics != EmptyLayoutMetrics;
 
-  static auto preallocateView = jni::findClassStatic(UIManagerJavaDescriptor)
-                                    ->getMethod<void(
-                                        jint,
-                                        jint,
-                                        jstring,
-                                        ReadableMap::javaobject,
-                                        jobject,
-                                        jobject,
-                                        jboolean)>("preallocateView");
+  static auto preallocateView =
+      jni::findClassStatic(UIManagerJavaDescriptor)
+          ->getMethod<void(
+              jint, jint, jstring, jobject, jobject, jobject, jboolean)>(
+              "preallocateView");
 
   // Do not hold onto Java object from C
   // We DO want to hold onto C object from Java, since we don't know the
@@ -826,8 +829,8 @@ void FabricMountingManager::preallocateShadowView(
     }
   }
 
-  local_ref<ReadableMap::javaobject> props = castReadableMap(
-      ReadableNativeMap::newObjectCxxArgs(shadowView.props->rawProps));
+  local_ref<JObject> props = getProps({}, shadowView);
+
   auto component = getPlatformComponentName(shadowView);
 
   preallocateView(
@@ -942,6 +945,8 @@ FabricMountingManager::FabricMountingManager(
   useOverflowInset_ = doesUseOverflowInset();
   shouldRememberAllocatedViews_ = config->getBool(
       "react_native_new_architecture:remember_views_on_mount_android");
+  useMapBufferForViewProps_ = config->getBool(
+      "react_native_new_architecture:use_mapbuffer_for_viewprops");
 }
 
 } // namespace react

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/FabricMountingManager.h

@@ -76,6 +76,11 @@ class FabricMountingManager {
   bool disableRevisionCheckForPreallocation_{false};
   bool useOverflowInset_{false};
   bool shouldRememberAllocatedViews_{false};
+  bool useMapBufferForViewProps_{false};
+
+  jni::local_ref<jobject> getProps(
+      ShadowView const &oldShadowView,
+      ShadowView const &newShadowView);
 };
 
 } // namespace react