Fix cleanup bug

Summary:
When I initially made TurboModuleManager.getModule thread-safe, I unintentionally broken TurboModule cleanup. This diff fixes that mistake.

## Mistake
```
  Override
  public void onCatalystInstanceDestroy() {
    synchronized (mTurboModuleCleanupLock) {
      mTurboModuleCleanupStarted = true;
    }

    final Set<String> turboModuleNames = new HashSet<>(mTurboModuleHolders.keySet());

    for (final String moduleName : turboModuleNames) {
      // Retrieve the TurboModule, possibly waiting for it to finish instantiating.
      final TurboModule turboModule = getModule(moduleName); // ERROR!

      if (turboModule != null) {
        // TODO(T48014458): Rename this to invalidate()
        ((NativeModule) turboModule).onCatalystInstanceDestroy();
      }
    }

```

Before calling `getModule(moduleName)`, I set `mTurboModuleCleanupStarted = true`. This assignment makes all calls to `getModule` return `null`, which means that none of the TurboModules were having their `onCatalystInstanceDestroy()` method invoked.

Changelog:
[Android][Fixed] - TurboModule cleanup

Reviewed By: fkgozali

Differential Revision: D21290582

fbshipit-source-id: 3645b9a4f8c6f41498ebd9d51f9b5775edf2dbd7

ReactAndroid/src/main/java/com/facebook/react/turbomodule/core/TurboModuleManager.java

@@ -104,13 +104,38 @@ public class TurboModuleManager implements JSIModule, TurboModuleRegistry {
     return mEagerInitModuleNames;
   }
 
+  @DoNotStrip
+  @Nullable
+  private CxxModuleWrapper getLegacyCxxModule(String moduleName) {
+    final TurboModule turboModule = getModule(moduleName);
+    if (!(turboModule instanceof CxxModuleWrapper)) {
+      return null;
+    }
+
+    return (CxxModuleWrapper) turboModule;
+  }
+
+  @DoNotStrip
+  @Nullable
+  private TurboModule getJavaModule(String moduleName) {
+    final TurboModule turboModule = getModule(moduleName);
+    if (turboModule instanceof CxxModuleWrapper) {
+      return null;
+    }
+
+    return turboModule;
+  }
+
   /**
-   * TurboModuleHolders are used as locks to ensure that when n threads race to create a
-   * TurboModule, only the first thread creates that TurboModule. All other n - 1 threads wait until
-   * the TurboModule is created and initialized.
+   * Return the TurboModule instance that corresponds to the provided moduleName.
+   *
+   * <p>This method: - Creates and initializes the module if it doesn't already exist. - Returns
+   * null after TurboModuleManager has been torn down.
    */
   @Nullable
-  private TurboModuleHolder getOrMaybeCreateTurboModuleHolder(String moduleName) {
+  public TurboModule getModule(String moduleName) {
+    TurboModuleHolder moduleHolder;
+
     synchronized (mTurboModuleCleanupLock) {
       if (mTurboModuleCleanupStarted) {
         /*
@@ -132,24 +157,22 @@ public class TurboModuleManager implements JSIModule, TurboModuleRegistry {
       if (!mTurboModuleHolders.containsKey(moduleName)) {
         mTurboModuleHolders.put(moduleName, new TurboModuleHolder());
       }
-      return mTurboModuleHolders.get(moduleName);
+
+      moduleHolder = mTurboModuleHolders.get(moduleName);
     }
+
+    return getModule(moduleName, moduleHolder);
   }
 
   /**
-   * If n threads race to create TurboModule x, then only the first thread should create x. All n -
-   * 1 other threads should wait until x is created and initialized.
+   * Given a TurboModuleHolder, and the TurboModule's moduleName, return the TurboModule instance.
    *
-   * <p>Note: After we've started cleanup, getModule will always return null.
+   * <p>Use the TurboModuleHolder to ensure that if n threads race to create TurboModule x, then
+   * only the first thread creates x. All n - 1 other threads wait until the x is created and
+   * initialized.
    */
   @Nullable
-  public TurboModule getModule(String moduleName) {
-    final TurboModuleHolder moduleHolder = getOrMaybeCreateTurboModuleHolder(moduleName);
-
-    if (moduleHolder == null) {
-      return null;
-    }
-
+  private TurboModule getModule(String moduleName, @NonNull TurboModuleHolder moduleHolder) {
     boolean shouldCreateModule = false;
 
     synchronized (moduleHolder) {
@@ -220,28 +243,6 @@ public class TurboModuleManager implements JSIModule, TurboModuleRegistry {
     }
   }
 
-  @DoNotStrip
-  @Nullable
-  private CxxModuleWrapper getLegacyCxxModule(String moduleName) {
-    final TurboModule turboModule = getModule(moduleName);
-    if (!(turboModule instanceof CxxModuleWrapper)) {
-      return null;
-    }
-
-    return (CxxModuleWrapper) turboModule;
-  }
-
-  @DoNotStrip
-  @Nullable
-  private TurboModule getJavaModule(String moduleName) {
-    final TurboModule turboModule = getModule(moduleName);
-    if (turboModule instanceof CxxModuleWrapper) {
-      return null;
-    }
-
-    return turboModule;
-  }
-
   /** Which TurboModules have been created? */
   public Collection<TurboModule> getModules() {
     final List<TurboModuleHolder> turboModuleHolders = new ArrayList<>();
@@ -305,11 +306,17 @@ public class TurboModuleManager implements JSIModule, TurboModuleRegistry {
       mTurboModuleCleanupStarted = true;
     }
 
-    final Set<String> turboModuleNames = new HashSet<>(mTurboModuleHolders.keySet());
+    for (final Map.Entry<String, TurboModuleHolder> moduleHolderEntry :
+        mTurboModuleHolders.entrySet()) {
+      final String moduleName = moduleHolderEntry.getKey();
+      final TurboModuleHolder moduleHolder = moduleHolderEntry.getValue();
 
-    for (final String moduleName : turboModuleNames) {
-      // Retrieve the TurboModule, possibly waiting for it to finish instantiating.
-      final TurboModule turboModule = getModule(moduleName);
+      /**
+       * ReactNative could start tearing down before this particular TurboModule has been fully
+       * initialized. In this case, we should wait for initialization to complete, before destroying
+       * the TurboModule.
+       */
+      final TurboModule turboModule = getModule(moduleName, moduleHolder);
 
       if (turboModule != null) {
         // TODO(T48014458): Rename this to invalidate()