introduce native api to access RuntimeExecutor (facebook#42882)

Summary:

Changelog: [Android][Added] - introduce native api to access RuntimeExecutor

This is the android equivalent of [PR#42758](facebook#42758).

From [PR#42758](facebook#42758)

> The goal of this API is to provide a safe way to access the jsi::runtime in bridgeless mode. The decision to limit access to the runtime in bridgeless was a conscious one - the runtime pointer is not thread-safe and its lifecycle must be managed correctly by owners.

> However, interacting with the runtime is an advanced use case we would want to support. Our recommended ways to access the runtime in bridgeless mode is either 1) via the RuntimeExecutor, or 2) via a C++ TurboModule.

This diff introduces the API that would allow for 1). because react context can be non-null before react instance is ready, this can still return null. however, the callsite should be cognizant of when this will happen. in the case of expomodules, the runtime should be ready when the module is init, unless it is a eager initialized module

Differential Revision: D53461821

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridge/ReactContext.java

@@ -206,6 +206,15 @@ public <T extends NativeModule> T getNativeModule(Class<T> nativeModuleInterface
     return mCatalystInstance.getNativeModule(nativeModuleInterface);
   }
 
+  /** @return the RuntimeExecutor, a thread-safe handler for accessing the runtime. */
+  @Nullable
+  public RuntimeExecutor getRuntimeExecutor() {
+    if (mCatalystInstance == null) {
+      raiseCatalystInstanceMissingException();
+    }
+    return mCatalystInstance.getRuntimeExecutor();
+  }
+
   /**
    * Calls RCTDeviceEventEmitter.emit to JavaScript, with given event name and an optional list of
    * arguments.

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/BridgelessReactContext.java

@@ -19,6 +19,7 @@
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.bridge.ReactNoCrashBridgeNotAllowedSoftException;
 import com.facebook.react.bridge.ReactSoftExceptionLogger;
+import com.facebook.react.bridge.RuntimeExecutor;
 import com.facebook.react.bridge.UIManager;
 import com.facebook.react.bridge.WritableNativeArray;
 import com.facebook.react.config.ReactFeatureFlags;
@@ -149,6 +150,14 @@ public Collection<NativeModule> getNativeModules() {
   public @Nullable <T extends NativeModule> T getNativeModule(Class<T> nativeModuleInterface) {
     return mReactHost.getNativeModule(nativeModuleInterface);
   }
+  /**
+   * @return the RuntimeExecutor, a thread-safe handler for accessing the runtime. If the runtime is
+   *     not initialized yet, it will return null.
+   */
+  @Override
+  public @Nullable RuntimeExecutor getRuntimeExecutor() {
+    return mReactHost.getRuntimeExecutor();
+  }
 
   @Override
   public void handleException(Exception e) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactHostImpl.java

@@ -38,6 +38,7 @@
 import com.facebook.react.bridge.ReactNoCrashBridgeNotAllowedSoftException;
 import com.facebook.react.bridge.ReactNoCrashSoftException;
 import com.facebook.react.bridge.ReactSoftExceptionLogger;
+import com.facebook.react.bridge.RuntimeExecutor;
 import com.facebook.react.bridge.UiThreadUtil;
 import com.facebook.react.bridge.queue.QueueThreadExceptionHandler;
 import com.facebook.react.bridge.queue.ReactQueueConfiguration;
@@ -542,7 +543,8 @@ private void setCurrentActivity(@Nullable Activity activity) {
     return reactInstance.getEventDispatcher();
   }
 
-  /* package */ @Nullable
+  /* package */
+  @Nullable
   FabricUIManager getUIManager() {
     final ReactInstance reactInstance = mReactInstanceTaskRef.get().getResult();
     if (reactInstance == null) {
@@ -567,7 +569,8 @@ FabricUIManager getUIManager() {
     return new ArrayList<>();
   }
 
-  /* package */ @Nullable
+  /* package */
+  @Nullable
   <T extends NativeModule> T getNativeModule(Class<T> nativeModuleInterface) {
     if (nativeModuleInterface == UIManagerModule.class) {
       ReactSoftExceptionLogger.logSoftExceptionVerbose(
@@ -583,6 +586,16 @@ <T extends NativeModule> T getNativeModule(Class<T> nativeModuleInterface) {
     return null;
   }
 
+  /* package */
+  @Nullable
+  RuntimeExecutor getRuntimeExecutor() {
+    final ReactInstance reactInstance = mReactInstanceTaskRef.get().getResult();
+    if (reactInstance != null) {
+      return reactInstance.getBufferedRuntimeExecutor();
+    }
+    return null;
+  }
+
   /* package */
   DefaultHardwareBackBtnHandler getDefaultBackButtonHandler() {
     return () -> {
@@ -699,6 +712,7 @@ public void removeBeforeDestroyListener(@NonNull Function0<Unit> onBeforeDestroy
   }
 
   /* package */ interface VeniceThenable<T> {
+
     void then(T t);
   }
 
@@ -913,6 +927,7 @@ private Task<ReactInstance> getOrCreateReactInstanceTask() {
                         });
 
                     class Result {
+
                       final ReactInstance mInstance = instance;
                       final ReactContext mContext = reactContext;
                       final boolean mIsReloading = mReloadTask != null;
@@ -1087,6 +1102,7 @@ private void startAttachedSurfaces(String method, ReactInstance reactInstance) {
   private @Nullable Task<ReactInstance> mReloadTask = null;
 
   private interface ReactInstanceTaskUnwrapper {
+
     @Nullable
     ReactInstance unwrap(Task<ReactInstance> task, String stage);
   }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactInstance.java

@@ -471,7 +471,7 @@ private native HybridData initHybrid(
 
   private native RuntimeExecutor getUnbufferedRuntimeExecutor();
 
-  private native RuntimeExecutor getBufferedRuntimeExecutor();
+  /* package */ native RuntimeExecutor getBufferedRuntimeExecutor();
 
   private native RuntimeScheduler getRuntimeScheduler();