play a very scary sound on each GC trigger

gc.kt

import rx.Observable
import rx.Subscriber
import rx.schedulers.Schedulers
import java.lang.ref.PhantomReference
import java.lang.ref.ReferenceQueue

fun gcTriggers(): Observable<Unit> =
    Observable.create(triggerLoop())
        .subscribeOn(Schedulers.newThread())

private fun triggerLoop() = { sub: Subscriber<in Unit> ->
  Thread.currentThread().priority = Thread.MIN_PRIORITY

  val queue = ReferenceQueue<Any>()
  var phantom = PhantomReference(Any(), queue)
  while (!sub.isUnsubscribed) {
    // blocks for up to 16 ms until the object is GC'd
    if (queue.remove(16) != null) {
      sub.onNext(Unit)
      phantom = PhantomReference(Any(), queue)
    }
  }
}

usage.kt

import android.media.RingtoneManager

val ringtone = lazy {
  val uri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION)
  RingtoneManager.getRingtone(this, uri)
}
gcTriggers().subscribe {
  val ring = ringtone.value
  ring.stop()
  ring.play()
}