LaunchActivity.kt

## LaunchActivity.kt
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.LifecycleObserver
import androidx.lifecycle.LifecycleOwner
import androidx.lifecycle.OnLifecycleEvent
import io.reactivex.Flowable
import io.reactivex.disposables.Disposable
import io.reactivex.schedulers.Schedulers
import timber.log.Timber
import java.util.concurrent.TimeUnit

class LaunchActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_launch)

    }

    override fun onResume() {
        super.onResume()

        Timber.i("create single")
        Flowable.range(0, 10_000)
                .delay(100, TimeUnit.MILLISECONDS)
                .subscribeOn(Schedulers.io())
                .subscribe({
                    Timber.i("counted $it")
                }, {})
                .dispose(Lifecycle.Event.ON_PAUSE)
    }

    fun Disposable.dispose(filter: Lifecycle.Event) {
        lifecycle.addObserver(Disposer(this, filter))
    }

    @Suppress("UNUSED", "UNUSED_PARAMETER")
    open class Disposer(
            private val disposable: Disposable,
            private val filter: Lifecycle.Event): LifecycleObserver {

        @OnLifecycleEvent(Lifecycle.Event.ON_ANY)
        fun onAny(source: LifecycleOwner, event: Lifecycle.Event) {
            if (event != filter) return
            if (!disposable.isDisposed) disposable.dispose()
            Timber.i("disposed")
        }
    }
}