Nonblocking cache

NonblockingCache.scala

/*©2013 Viktor Klang*/
package akka.util
import java.util.concurrent.atomic.AtomicReference
import scala.concurrent.{ Future, ExecutionContext }
import scala.annotation.tailrec
class Cache[K, V](__ec: ExecutionContext, throughput: Int) extends AtomicReference[Map[K, V]] {
  implicit val executor = SerializedSuspendableExecutionContext(throughput)(__ec)
  @tailrec final def update(f: Map[K, V] ⇒ Map[K, V]): Map[K, V] = {
    val v = get
    val nv = f(v)
    if ((v eq get) && compareAndSet(v, nv)) nv else update(f)
  }
  def alter(f: Map[K, V] ⇒ Map[K, V]): Future[Map[K, V]] = Future(update(f))
}

val c = new Cache[Foo, Bar](ExecutionContext.Implicits.global, 16)

/* Usage readers */
c.get.get("value")

/* Usage writers */
c.alter(_.updated(key, calculateValue))