I need advice. branch/todo-mvp-clean. LongRunningUseCase

[westman2000]

Suppose there is such UseCase

And Presenter who using it.

When user start UseCase, i show loading, but because this is long running operation, user can close this screen(press back button, close activity), or even close application(press home button).
In this case, will be called detachView() and onDestroyed() (presenter will be destroyed here)

But since the operation is continued in the background, presenter will receive
onSuccess(LongRunningUseCase.ResponseValue response)
but because view already detached, there will be Error.

And my questions are:

1. How to avoid this error? I understand i can just check if view is attached isViewAttached(). but maybe there is a more elegant solution? For example how I can unsubscribe from UseCase if presenter destroyed, and then callback will not be called?
2. I do not understand how and why there is a function call onSuccess in the presenter, if presenter was already destroyed in MVPCPresenterLoader.onReset()
3. Somebody thought to create an intermediate buffer(let's called ViewState) between the Presenter and View to save commands for the View. In case you Presenter was disconnected from the View, and background thread finish loading, we need to hide the ProgressBar and display data. But this commands must be send to View only after attachView... In generally i speak about somesing like this

[ErikHellman]

The solution here is to have the UseCaseHandler return an object that implements something like cancel(). The presenter needs to define a stop() or unsubscribe() method that the view will call once it gets detached.