I need to do some clean up just right after all the `Subscriber`s unsubscribe from my `Observable`, ...

# rx

[yougin]

I need to do some clean up just right after all the `Subscriber`s unsubscribe from my Observable, doOnUnsubscribe is invoked upon unsubscribe (dispose) by each of them. Is there a way to wait until everyone unsubscribes?

[bezrukov]

Most likely your Observable is cold, so in fact Subscribers subscribe to different observables. So most likely you need to convert your cold observable to hot, for example by replay().refCount() and then share it between subscribers. After that doOnUnsubscribe will be called only when every subscribe unsubscribes

[yougin]

@bezrukov It's hot, I've tried replay().refCount() but it doesn't seem to make any difference, i.e. doOnDispose is invoked for every subscriber

[bezrukov]

What is order of operators do you use?

[yougin]

This same idea just crossed my mind, I used to have doOnDispose right before replay().refCount(), trying to place it after these two

[yougin]

Nope, got the same behaviour

[yougin]

So, it's

myObservable
        .doOnSubscribe { init() }
        .replay()
        .refCount()
        .doOnDispose { cleanUp() }

[bezrukov]

tried it now, and it works:

private val cold = Observable.interval(1, TimeUnit.SECONDS)
    .subscribeOn(<http://Schedulers.io|Schedulers.io>())
    .observeOn(<http://Schedulers.io|Schedulers.io>())

private val hot = cold.doOnDispose { println("Cold dispose") }
    .replay().refCount()
    .doOnDispose { println("Hot dispose") }

fun main() {
    val first = hot
        .subscribe {
            println("1 $it")
        }
    val second = hot
        .subscribe {
            println("2 $it")
        }

    Thread.sleep(5000)
    println("dispose first")
    first.dispose()
    Thread.sleep(5000)
    println("dispose second")
    second.dispose()
    Thread.sleep(3000)
}

[bezrukov]

It prints Hot dispose twice, but Cold dispose once

[yougin]

@bezrukov thank you, makes sense to me now.