Cannot access `RuntimeExecutor` through `RCTCxxBridge` on iOS

Description

It is currently not possible to access RuntimeExecutor through RCTCxxBridge on iOS even though it’s available through _reactInstance->getRuntimeExecutor():

@implementation RCTMyModule

@synthesize bridge = _bridge;

RCT_EXPORT_MODULE()

- (void)initialize {
  RCTCxxBridge *cxxBridge = (RCTCxxBridge *)_bridge;

  // Cannot access `RuntimeExecutor` through `cxxBridge`
}

@end

On Android, RuntimeExecutor can be accessed through CatalystInstance:

public class MyModule extends ReactContextBaseJavaModule {
  public MyModule(ReactApplicationContext reactContext) {
    super(reactContext);
  }

  public void initialize() {
    RuntimeExecutor runtimeExecutor = this
      .getReactApplicationContext()
      .getCatalystInstance()
      .getRuntimeExecutor();
  }
}

Should RCTCxxBridge expose the underlying Instance similar to how it’s done on Android or simply expose a runtimeExecutor getter?

I’m currently using a shim based on CallInvoker to work around this:

facebook::react::RuntimeExecutor runtimeExecutor =
  [cxxBridge](std::function<void(facebook::jsi::Runtime & runtime)> &&callback) {
    cxxBridge.jsCallInvoker->invokeAsync(
      [cxxBridge, callback = std::move(callback)]() {
        callback(*(facebook::jsi::Runtime *)(cxxBridge.runtime));
      }
    );
  };

Version

0.66.4

Output of npx react-native info

System: OS: macOS 11.6.2 CPU: (4) x64 Intel® Core™ i5-4308U CPU @ 2.80GHz Memory: 77.92 MB / 8.00 GB Shell: 5.8 - /bin/zsh Binaries: Node: 17.2.0 - /usr/local/bin/node Yarn: 1.22.17 - /usr/local/bin/yarn npm: 8.1.4 - /usr/local/bin/npm Watchman: 2021.12.06.00 - /usr/local/bin/watchman Managers: CocoaPods: 1.11.2 - /usr/local/bin/pod SDKs: iOS SDK: Platforms: DriverKit 21.2, iOS 15.2, macOS 12.1, tvOS 15.2, watchOS 8.3 Android SDK: Not Found IDEs: Android Studio: 2020.3 AI-203.7717.56.2031.7784292 Xcode: 13.2.1/13C100 - /usr/bin/xcodebuild Languages: Java: 17.0.1 - /usr/bin/javac npmPackages: @react-native-community/cli: Not Found react: ^17.0.2 => 17.0.2 react-native: ^0.66.4 => 0.66.4 react-native-macos: Not Found npmGlobalPackages: react-native: Not Found

Steps to reproduce

1. Create a native module for iOS.
2. Access its associated RCTBridge and cast it to RCTCxxBridge.
3. Notice how there’s no way to access the RuntimeExecutor hiding behind _reactInstance->getRuntimeExecutor().

Snack, code example, screenshot, or link to a repository

No response

[kasperisager]

On a related note, I might be holding RuntimeExecutor wrong. I’m using it to install JSI bindings for a native module, but on Android, which uses _reactInstance->getRuntimeExecutor(), I’m not seeing the bindings in the JavaScript context of the application:

executeAsynchronously(runtimeExecutor, [](Runtime &runtime) {
  runtime.global().setProperty(
    runtime,
    "__myFunction",
    Function::createFromHostFunction(...)
  );
});

When the application loads, __myFunction is undefined. It works just fine on iOS with the RuntimeExecutor shim described previously.

Edit: The cause has been identified in https://github.com/facebook/react-native/issues/32813#issuecomment-1020021633.

[kasperisager]

Is there anything I can do to help this issue along?