fix(android): fix bug w/ LA where animation never executed when scheduled from JS

packages/react-native-reanimated/Common/cpp/reanimated/LayoutAnimations/LayoutAnimationsProxy.cpp

@@ -395,18 +395,18 @@ void LayoutAnimationsProxy::addOngoingAnimations(
     SurfaceId surfaceId,
     ShadowViewMutationList &mutations) const {
   auto &updateMap = surfaceManager.getUpdateMap(surfaceId);
+  if (updateMap.empty()) {
+    return;
+  }
+
 #ifdef ANDROID
   std::vector<int> tagsToUpdate;
+  tagsToUpdate.reserve(updateMap.size());
   for (auto &[tag, updateValues] : updateMap) {
     tagsToUpdate.push_back(tag);
   }
 
-  auto maybeCorrectedTags = preserveMountedTags_(tagsToUpdate);
-  if (!maybeCorrectedTags.has_value()) {
-    return;
-  }
-
-  auto correctedTags = maybeCorrectedTags->get();
+  auto correctedTags = preserveMountedTags_(tagsToUpdate);
 
   // since the map is not updated, we can assume that the ordering of tags in
   // correctedTags matches the iterator

packages/react-native-reanimated/Common/cpp/reanimated/Tools/PlatformDepMethodsHolder.h

@@ -38,7 +38,7 @@ using SynchronouslyUpdateUIPropsFunction =
     std::function<void(const int, const folly::dynamic &)>;
 #endif // ANDROID
 using PreserveMountedTagsFunction =
-    std::function<std::optional<std::unique_ptr<int[]>>(std::vector<int> &)>;
+    std::function<std::unique_ptr<int[]>(std::vector<int> &)>;
 using GetAnimationTimestampFunction = std::function<double(void)>;
 
 using ProgressLayoutAnimationFunction =

packages/react-native-reanimated/android/src/main/cpp/reanimated/android/NativeProxy.cpp

@@ -174,21 +174,14 @@ void NativeProxy::maybeFlushUIUpdatesQueue() {
   method(javaPart_.get());
 }
 
-std::optional<std::unique_ptr<int[]>> NativeProxy::preserveMountedTags(
+std::unique_ptr<int[]> NativeProxy::preserveMountedTags(
     std::vector<int> &tags) {
-  if (tags.empty()) {
-    return {};
-  }
-
   static const auto method =
-      getJniMethod<jboolean(jni::alias_ref<jni::JArrayInt>)>(
-          "preserveMountedTags");
+      getJniMethod<void(jni::alias_ref<jni::JArrayInt>)>("preserveMountedTags");
   auto jArrayInt = jni::JArrayInt::newArray(tags.size());
   jArrayInt->setRegion(0, tags.size(), tags.data());
 
-  if (!method(javaPart_.get(), jArrayInt)) {
-    return {};
-  }
+  method(javaPart_.get(), jArrayInt);
 
   auto region = jArrayInt->getRegion(0, tags.size());
   return region;

packages/react-native-reanimated/android/src/main/cpp/reanimated/android/NativeProxy.h

@@ -53,8 +53,7 @@ class NativeProxy : public jni::HybridClass<NativeProxy>,
   // std::shared_ptr<facebook::react::Scheduler> reactScheduler_;
   // std::shared_ptr<EventListener> eventListener_;
   void installJSIBindings();
-  std::optional<std::unique_ptr<int[]>> preserveMountedTags(
-      std::vector<int> &tags);
+  std::unique_ptr<int[]> preserveMountedTags(std::vector<int> &tags);
   void synchronouslyUpdateUIProps(
       const std::vector<int> &intBuffer,
       const std::vector<double> &doubleBuffer);

packages/react-native-reanimated/android/src/main/java/com/swmansion/reanimated/NativeProxy.java

@@ -289,19 +289,16 @@ private static String transformCommandToString(int transformCommand) {
     };
   }
 
+  /** Modifies tags in place, setting not mounted view tags to -1 at their index. */
   @DoNotStrip
-  public boolean preserveMountedTags(int[] tags) {
-    if (!UiThreadUtil.isOnUiThread()) {
-      return false;
-    }
-
+  public void preserveMountedTags(int[] tags) {
     for (int i = 0; i < tags.length; i++) {
+      // Note: resolveView has assertOnUiThread, which only logs as softexception in debug
+      // It is actually completely thread safe and there is a RFC in RN to do something about it
       if (mFabricUIManager.resolveView(tags[i]) == null) {
         tags[i] = -1;
       }
     }
-
-    return true;
   }
 
   @DoNotStrip