gistfile1.scala

@volatile var callbackExecuted = false

val ks = (1 to 10).map(i => s"client_key_$i")
val kvs = ks.zip(1 to 10)

val sets: Seq[Future[Boolean]] = kvs map {
  case (k, v) => client.set(k, v)
}

val setResult = Future.sequence(sets) map { r: Seq[Boolean] =>
  callbackExecuted = true
  r
}

callbackExecuted should be (false)
setResult.futureValue should contain only (true)
callbackExecuted should be (true)

callbackExecuted = false
val gets: Seq[Future[Option[Long]]] = ks.map { k => client.get[Long](k) }
val getResult = Future.sequence(gets).map { rs =>
  callbackExecuted = true
  rs.flatten.sum
}

callbackExecuted should be (false)
getResult.futureValue should equal (55)
callbackExecuted should be (true)