Using CallbackWrapper in async operations

[stephenkopylov]

Hello!
First of all - thank you for your amazing libraries, guys!

I analysed your cxx code for a little and found that you're not using Facebook's CallbackWrapper at all

It would be really useful for example here (NativeReanimatedModule.cpp)

jsi::Value NativeReanimatedModule::getViewProp(
    jsi::Runtime &rt,
    const jsi::Value &viewTag,
    const jsi::Value &propName,
    const jsi::Value &callback) {
  const int viewTagInt = static_cast<int>(viewTag.asNumber());
  std::string propNameStr = propName.asString(rt).utf8(rt);
  jsi::Function fun = callback.getObject(rt).asFunction(rt);
  std::shared_ptr<jsi::Function> funPtr =
      std::make_shared<jsi::Function>(std::move(fun));

  scheduler->scheduleOnUI([&rt, viewTagInt, funPtr, this, propNameStr]() {
    const jsi::String propNameValue =
        jsi::String::createFromUtf8(rt, propNameStr);
    jsi::Value result = propObtainer(rt, viewTagInt, propNameValue);
    std::string resultStr = result.asString(rt).utf8(rt);

    scheduler->scheduleOnJS([&rt, resultStr, funPtr]() {
      const jsi::String resultValue =
          jsi::String::createFromUtf8(rt, resultStr);
      funPtr->call(rt, resultValue);
    });
  });

  return jsi::Value::undefined();
}

If JS runtime was recreated (for example because of CodePush update, or hot reloading while debugging) we cannot be sure that funPtr is still alive inside scheduleOnUI and scheduleOnJS blocks

In our own TurboModules we use CallbackWrapper from <ReactCommon/TurboModuleUtils.h> and it works perfect - if runtime was destroyed all callbacks are destroyed too.
So, using CallbackWrapper your code will be more like this:

jsi::Value NativeReanimatedModule::getViewProp(
    jsi::Runtime &rt,
    const jsi::Value &viewTag,
    const jsi::Value &propName,
    const jsi::Value &callback) {
  const int viewTagInt = static_cast<int>(viewTag.asNumber());
  std::string propNameStr = propName.asString(rt).utf8(rt);
  jsi::Function fun = callback.getObject(rt).asFunction(rt);
  auto weakWrapper = CallbackWrapper::createWeak(fun,rt,jsInvoker_);

  scheduler->scheduleOnUI([&rt, viewTagInt, weakWrapper, this, propNameStr]() {
    auto strongWrapper = weakWrapper.lock();
    if (!strongWrapper) {
      return;
    }

    const jsi::String propNameValue =
        jsi::String::createFromUtf8(rt, propNameStr);
    jsi::Value result = propObtainer(rt, viewTagInt, propNameValue);
    std::string resultStr = result.asString(rt).utf8(rt);

    scheduler->scheduleOnJS([&rt, resultStr, weakWrapper]() {
      auto strongWrapper = weakWrapper.lock();
      if (!strongWrapper) {
        return;
      }
    
      const jsi::String resultValue =
          jsi::String::createFromUtf8(rt, resultStr);
      strongWrapper->call(rt, resultValue);
    });
  });

  return jsi::Value::undefined();
}

What do you think?