Clear out CreateReactInstanceTaskRef early when destroying (#46544)

Summary:
Pull Request resolved: #46544

Experiments with `completeReactInstanceCreationOnBgThreadOnAndroid` have shown a native crash in this code path, but it also existed previously.

I believe this is due to the ordering of ReactInstance teardown: we first destroy the ReactInstance, and only then destroy the reference to it in mCreateReactInstanceTaskRef. When using the immediate executor and completeReactInstanceCreationOnBgThreadOnAndroid, we read the react instance from the task, which may no longer be valid at this point. Resetting the task at the earliest point should mitigate the issue.

Changelog: [Internal]

Reviewed By: markv

Differential Revision: D62872625

fbshipit-source-id: 5aaccd53433ca806d2b93f7e3dd2bcf9bf8c09a8

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

@@ -1400,9 +1400,14 @@ private Task<ReactInstance> getOrCreateReloadTask(String reason) {
  createReactInstanceUnwrapper("Reload", method, reason);
 
  if (mReloadTask == null) {
+ // When using the immediate executor, we want to avoid scheduling any further work immediately
+ // when destruction is kicked off.
+ Task<ReactInstance> createTask =
+ ReactNativeFeatureFlags.completeReactInstanceCreationOnBgThreadOnAndroid()
+ ? mCreateReactInstanceTaskRef.getAndReset()
+ : mCreateReactInstanceTaskRef.get();
  mReloadTask =
- mCreateReactInstanceTaskRef
- .get()
+ createTask
  .continueWithTask(
  (task) -> {
  log(method, "Starting React Native reload");
@@ -1499,8 +1504,13 @@ private Task<ReactInstance> getOrCreateReloadTask(String reason) {
  reactInstance.destroy();
  }
 
- log(method, "Resetting createReactInstance task ref");
- mCreateReactInstanceTaskRef.reset();
+ // Originally, we reset the instance task ref quite late, leading to potential
+ // racing invocations while shutting down
+ if (!ReactNativeFeatureFlags
+ .completeReactInstanceCreationOnBgThreadOnAndroid()) {
+ log(method, "Resetting createReactInstance task ref");
+ mCreateReactInstanceTaskRef.reset();
+ }
 
  log(method, "Resetting start task ref");
  mStartTask = null;
@@ -1578,9 +1588,15 @@ private Task<Void> getOrCreateDestroyTask(final String reason, @Nullable Excepti
  createReactInstanceUnwrapper("Destroy", method, reason);
 
  if (mDestroyTask == null) {
+ // When using the immediate executor, we want to avoid scheduling any further work immediately
+ // when destruction is kicked off.
+ Task<ReactInstance> createTask =
+ ReactNativeFeatureFlags.completeReactInstanceCreationOnBgThreadOnAndroid()
+ ? mCreateReactInstanceTaskRef.getAndReset()
+ : mCreateReactInstanceTaskRef.get();
+
  mDestroyTask =
- mCreateReactInstanceTaskRef
- .get()
+ createTask
  .continueWithTask(
  task -> {
  log(method, "Starting React Native destruction");
@@ -1608,7 +1624,6 @@ private Task<Void> getOrCreateDestroyTask(final String reason, @Nullable Excepti
  }
 
  final ReactContext reactContext = mBridgelessReactContextRef.getNullable();
-
  if (reactContext == null) {
  raiseSoftException(method, "ReactContext is null. Destroy reason: " + reason);
  }
@@ -1624,7 +1639,6 @@ private Task<Void> getOrCreateDestroyTask(final String reason, @Nullable Excepti
  task -> {
  final ReactInstance reactInstance =
  reactInstanceTaskUnwrapper.unwrap(task, "2: Stopping surfaces");
-
  if (reactInstance == null) {
  raiseSoftException(method, "Skipping surface shutdown: ReactInstance null");
  return task;
@@ -1701,8 +1715,13 @@ private Task<Void> getOrCreateDestroyTask(final String reason, @Nullable Excepti
  reactInstance.destroy();
  }
 
- log(method, "Resetting createReactInstance task ref");
- mCreateReactInstanceTaskRef.reset();
+ // Originally, we reset the instance task ref quite late, leading to potential
+ // racing invocations while shutting down
+ if (!ReactNativeFeatureFlags
+ .completeReactInstanceCreationOnBgThreadOnAndroid()) {
+ log(method, "Resetting createReactInstance task ref");
+ mCreateReactInstanceTaskRef.reset();
+ }
 
  log(method, "Resetting start task ref");
  mStartTask = null;