packages/react-native/Libraries/WebPerformance/MemoryInfo.js

@@ -11,7 +11,7 @@
 
 // flowlint unsafe-getters-setters:off
 
-export type MemoryInfoLike = {
+type MemoryInfoLike = {
   jsHeapSizeLimit: ?number,
   totalJSHeapSize: ?number,
   usedJSHeapSize: ?number,

packages/react-native/Libraries/WebPerformance/NativePerformance.cpp

@@ -54,23 +54,41 @@ std::unordered_map<std::string, double> NativePerformance::getSimpleMemoryInfo(
   return heapInfoToJs;
 }
 
-ReactNativeStartupTiming NativePerformance::getReactNativeStartupTiming(
-    jsi::Runtime &rt) {
-  ReactNativeStartupTiming result = {0, 0, 0, 0, 0, 0};
+std::unordered_map<std::string, double>
+NativePerformance::getReactNativeStartupTiming(jsi::Runtime &rt) {
+  std::unordered_map<std::string, double> result;
 
   ReactMarker::StartupLogger &startupLogger =
       ReactMarker::StartupLogger::getInstance();
-  result.startTime = startupLogger.getAppStartupStartTime();
-  if (result.startTime == 0) {
-    result.startTime = startupLogger.getInitReactRuntimeStartTime();
+  if (!std::isnan(startupLogger.getAppStartupStartTime())) {
+    result["startTime"] = startupLogger.getAppStartupStartTime();
+  } else if (!std::isnan(startupLogger.getInitReactRuntimeStartTime())) {
+    result["startTime"] = startupLogger.getInitReactRuntimeStartTime();
+  }
+
+  if (!std::isnan(startupLogger.getInitReactRuntimeStartTime())) {
+    result["initializeRuntimeStart"] =
+        startupLogger.getInitReactRuntimeStartTime();
+  }
+
+  if (!std::isnan(startupLogger.getRunJSBundleStartTime())) {
+    result["executeJavaScriptBundleEntryPointStart"] =
+        startupLogger.getRunJSBundleStartTime();
+  }
+
+  if (!std::isnan(startupLogger.getRunJSBundleEndTime())) {
+    result["executeJavaScriptBundleEntryPointEnd"] =
+        startupLogger.getRunJSBundleEndTime();
+  }
+
+  if (!std::isnan(startupLogger.getInitReactRuntimeEndTime())) {
+    result["initializeRuntimeEnd"] = startupLogger.getInitReactRuntimeEndTime();
   }
-  result.initializeRuntimeStart = startupLogger.getInitReactRuntimeStartTime();
-  result.executeJavaScriptBundleEntryPointStart =
-      startupLogger.getRunJSBundleStartTime();
-  result.executeJavaScriptBundleEntryPointEnd =
-      startupLogger.getRunJSBundleEndTime();
-  result.initializeRuntimeEnd = startupLogger.getInitReactRuntimeEndTime();
-  result.endTime = startupLogger.getAppStartupEndTime();
+
+  if (!std::isnan(startupLogger.getAppStartupEndTime())) {
+    result["endTime"] = startupLogger.getAppStartupEndTime();
+  }
+
   return result;
 }
 

packages/react-native/Libraries/WebPerformance/NativePerformance.h

@@ -18,25 +18,6 @@ class PerformanceEntryReporter;
 
 #pragma mark - Structs
 
-using ReactNativeStartupTiming =
-    NativePerformanceCxxBaseReactNativeStartupTiming<
-        int32_t,
-        int32_t,
-        int32_t,
-        int32_t,
-        int32_t,
-        int32_t>;
-
-template <>
-struct Bridging<ReactNativeStartupTiming>
-    : NativePerformanceCxxBaseReactNativeStartupTimingBridging<
-          int32_t,
-          int32_t,
-          int32_t,
-          int32_t,
-          int32_t,
-          int32_t> {};
-
 #pragma mark - implementation
 
 class NativePerformance : public NativePerformanceCxxSpec<NativePerformance>,
@@ -70,7 +51,8 @@ class NativePerformance : public NativePerformanceCxxSpec<NativePerformance>,
 
   // Collect and return the RN app startup timing information for performance
   // tracking.
-  ReactNativeStartupTiming getReactNativeStartupTiming(jsi::Runtime &rt);
+  std::unordered_map<std::string, double> getReactNativeStartupTiming(
+      jsi::Runtime &rt);
 
  private:
 };

packages/react-native/Libraries/WebPerformance/NativePerformance.js

@@ -12,16 +12,9 @@ import type {TurboModule} from '../TurboModule/RCTExport';
 
 import * as TurboModuleRegistry from '../TurboModule/TurboModuleRegistry';
 
-export type NativeMemoryInfo = {[key: string]: number};
+export type NativeMemoryInfo = {[key: string]: ?number};
 
-export type ReactNativeStartupTiming = {|
-  startTime: number,
-  endTime: number,
-  initializeRuntimeStart: number,
-  initializeRuntimeEnd: number,
-  executeJavaScriptBundleEntryPointStart: number,
-  executeJavaScriptBundleEntryPointEnd: number,
-|};
+export type ReactNativeStartupTiming = {[key: string]: ?number};
 
 export interface Spec extends TurboModule {
   +mark: (name: string, startTime: number) => void;

packages/react-native/Libraries/WebPerformance/Performance.js

@@ -143,9 +143,22 @@ export default class Performance {
   // Startup metrics is not used in web, but only in React Native.
   get reactNativeStartupTiming(): ReactNativeStartupTiming {
     if (NativePerformance?.getReactNativeStartupTiming) {
-      return new ReactNativeStartupTiming(
-        NativePerformance.getReactNativeStartupTiming(),
-      );
+      const {
+        startTime,
+        endTime,
+        initializeRuntimeStart,
+        initializeRuntimeEnd,
+        executeJavaScriptBundleEntryPointStart,
+        executeJavaScriptBundleEntryPointEnd,
+      } = NativePerformance.getReactNativeStartupTiming();
+      return new ReactNativeStartupTiming({
+        startTime,
+        endTime,
+        initializeRuntimeStart,
+        initializeRuntimeEnd,
+        executeJavaScriptBundleEntryPointStart,
+        executeJavaScriptBundleEntryPointEnd,
+      });
     }
     return new ReactNativeStartupTiming();
   }

packages/react-native/Libraries/WebPerformance/ReactNativeStartupTiming.js

@@ -11,22 +11,30 @@
 
 // flowlint unsafe-getters-setters:off
 
-import type {ReactNativeStartupTiming as ReactNativeStartupTimingType} from './NativePerformance';
+type ReactNativeStartupTimingLike = {
+  startTime: ?number,
+  endTime: ?number,
+  initializeRuntimeStart: ?number,
+  initializeRuntimeEnd: ?number,
+  executeJavaScriptBundleEntryPointStart: ?number,
+  executeJavaScriptBundleEntryPointEnd: ?number,
+};
 
 // Read-only object with RN startup timing information.
 // This is returned by the performance.reactNativeStartup API.
 export default class ReactNativeStartupTiming {
-  // All time information here are in ms. To match web spec,
-  // the default value for timings are zero if not present.
-  // See https://www.w3.org/TR/performance-timeline/#performancetiming-interface
-  _startTime = 0;
-  _endTime = 0;
-  _initializeRuntimeStart = 0;
-  _initializeRuntimeEnd = 0;
-  _executeJavaScriptBundleEntryPointStart = 0;
-  _executeJavaScriptBundleEntryPointEnd = 0;
+  // All time information here are in ms. The values may be null if not provided.
+  // We do NOT match web spect here for two reasons:
+  // 1. The `ReactNativeStartupTiming` is non-standard API
+  // 2. The timing information is relative to the time origin, which means `0` has valid meaning
+  _startTime: ?number;
+  _endTime: ?number;
+  _initializeRuntimeStart: ?number;
+  _initializeRuntimeEnd: ?number;
+  _executeJavaScriptBundleEntryPointStart: ?number;
+  _executeJavaScriptBundleEntryPointEnd: ?number;
 
-  constructor(startUpTiming: ?ReactNativeStartupTimingType) {
+  constructor(startUpTiming: ?ReactNativeStartupTimingLike) {
     if (startUpTiming != null) {
       this._startTime = startUpTiming.startTime;
       this._endTime = startUpTiming.endTime;
@@ -42,42 +50,42 @@ export default class ReactNativeStartupTiming {
   /**
    * Start time of the RN app startup process. This is provided by the platform by implementing the `ReactMarker.setAppStartTime` API in the native platform code.
    */
-  get startTime(): number {
+  get startTime(): ?number {
     return this._startTime;
   }
 
   /**
    * End time of the RN app startup process. This is equal to `executeJavaScriptBundleEntryPointEnd`.
    */
-  get endTime(): number {
+  get endTime(): ?number {
     return this._endTime;
   }
 
   /**
    * Start time when RN runtime get initialized. This is when RN infra first kicks in app startup process.
    */
-  get initializeRuntimeStart(): number {
+  get initializeRuntimeStart(): ?number {
     return this._initializeRuntimeStart;
   }
 
   /**
    * End time when RN runtime get initialized. This is the last marker before ends of the app startup process.
    */
-  get initializeRuntimeEnd(): number {
+  get initializeRuntimeEnd(): ?number {
     return this._initializeRuntimeEnd;
   }
 
   /**
    * Start time of JS bundle being executed. This indicates the RN JS bundle is loaded and start to be evaluated.
    */
-  get executeJavaScriptBundleEntryPointStart(): number {
+  get executeJavaScriptBundleEntryPointStart(): ?number {
     return this._executeJavaScriptBundleEntryPointStart;
   }
 
   /**
    * End time of JS bundle being executed. This indicates all the synchronous entry point jobs are finished.
    */
-  get executeJavaScriptBundleEntryPointEnd(): number {
+  get executeJavaScriptBundleEntryPointEnd(): ?number {
     return this._executeJavaScriptBundleEntryPointEnd;
   }
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/ViewManagersPropertyCache.java

@@ -393,6 +393,11 @@ public BoxedColorPropSetter(ReactProp prop, Method setter) {
    */
   /*package*/ static Map<String, PropSetter> getNativePropSettersForShadowNodeClass(
       Class<? extends ReactShadowNode> cls) {
+    if (cls == null) {
+      return EMPTY_PROPS_MAP;
+    }
+    ;
+
     for (Class iface : cls.getInterfaces()) {
       if (iface == ReactShadowNode.class) {
         return EMPTY_PROPS_MAP;

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

@@ -274,10 +274,16 @@ void FabricMountingManager::executeMount(
     std::lock_guard allocatedViewsLock(allocatedViewsMutex_);
 
     auto allocatedViewsIterator = allocatedViewRegistry_.find(surfaceId);
-    auto const &allocatedViewTags =
+    auto defaultAllocatedViews = butter::set<Tag>{};
+    // Do not remove `defaultAllocatedViews` or initialize `butter::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.
+    const auto &allocatedViewTags =
         allocatedViewsIterator != allocatedViewRegistry_.end()
         ? allocatedViewsIterator->second
-        : butter::set<Tag>{};
+        : defaultAllocatedViews;
     if (allocatedViewsIterator == allocatedViewRegistry_.end()) {
       LOG(ERROR) << "Executing commit after surface was stopped!";
     }