feat: make reactHost accessible

[WoLewicki]

Summary:

On bridgeless mode, reactHost is kept in memory even after destroying the DefaultReactNativeHost in brownfield scenario. Since it keeps references to the modules, they are not deallocated, and their initialize methods are not fired again when creating new instance of react-native later. It breaks the behavior of e.g. react-native-screens, which wants to listen for mutations and should get new FabricUIManager: https://github.com/software-mansion/react-native-screens/blob/20b7e83782cd5f79ddd0d61dadc13eeb4db4b258/android/src/main/java/com/swmansion/rnscreens/ScreensModule.kt#L45.

By adding invalidate method, which cleans up the reactHost instance, we can achieve it.

Changelog:

[ANDROID] [FIXED] - add invalidate method for destroying reactHost instance.

Test Plan:

In brownfield scenario, destroy the instance of RN and see that modules are also destroyed.

[cortinico]

/rebase

[cortinico]

Thanks for sending this over @WoLewicki This sounds like a reasonable approach, but I'd like to have @mdvacca 's opinion on this as well

[arushikesarwani94]

IIRC for internal apps use-case we were able to make use of getReactHost().destroy() to address this scenario without needing an explicit invalidate() in DefaultReactHost

cc: @shwanton

[cortinico]

I see that ReactNativeHost already has a clear() method.
Could we instead do the invalidation in the DefaultReactHost.clear() method instead of having to create a brand new invalidate() abstract method?

[WoLewicki]

Ok so clear is a public API for cleaning all of those instances? If so, I think it will be the correct place to put it there then.

[WoLewicki]

I changed it but I am not sure if the INSTANCE is the proper way of getting the instance of kotlin object.

[cortinico]

can you instead override fun clear(), call super.clear() and set the reactHost to null here?

[WoLewicki]

I am not sure I get it. DefaultReactHost does not inherit from ReactNativeHost so how can I override clear method in it? Or am I messing it up?

[cortinico]

@WoLewicki you're right, I misread the class title.

I'd suggest instead we do the following:

• Here make public fun invalidate() be internal
• Inside DefaultReactNativeHost add the following:

  override fun clear() {
    super.clear()
    DefaultReactHost.invalidate()
  }

[WoLewicki]

Done

[cortinico]

this is probably not needed

[facebook-github-bot]

@cortinico has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@cortinico merged this pull request in 07769d4.

[react-native-bot]

This pull request was successfully merged by @WoLewicki in 07769d4

^{When will my fix make it into a release? | How to file a pick request?}

[cortinico]

@WoLewicki sorry this took a bit longer. I've also update the commit message/description to reflect the correct behavior 07769d4

[WoLewicki]

Ok thanks