Akka's ActorCaching

ActorCaching.scala

import akka.actor.{Actor, ActorLogging, ExtendedActorSystem, Extension, ExtensionId, ExtensionIdProvider}
import akka.pattern.pipe
import com.typesafe.config.Config

import scala.concurrent.Future
import scala.concurrent.duration.Duration

object ActorCaching {
  case class SaveToCache(msg: Any, response: Any)
  case class RemoveFromCache(msg: Any)
}

trait ActorCaching { this: Actor with ActorLogging =>
  import ActorCaching._
  import context.dispatcher

  private val cache = ActorCache()
  private val cacheSettings = ActorCacheSettings(context.system)

  override def receive: Receive = {
    case SaveToCache(msg, response) =>
      cache.put(msg, response)
      context.system.scheduler.scheduleOnce(cacheSettings.defaultTll, self, RemoveFromCache(msg))

    case RemoveFromCache(msg) =>
      cache.remove(msg)

    case msg if cache.contains(msg) =>
      sender ! cache.get(msg)

    case msg if cachedReceive.isDefinedAt(msg) =>
      cachedReceive(msg)

  }

  def respond[A](msg: Any, response: Future[A], cache: Boolean = true): Unit = {
    if (cache) response.foreach(r => self ! SaveToCache(msg, r))
    response pipeTo sender()
  }

  def cachedReceive: Receive

}

// ActorCache
class ActorCache {
  private var cache: Map[Any, Any] = Map()
  def put(msg: Any, response: Any): Unit = cache = cache + (msg -> response)
  def get(msg: Any): Any = cache(msg)
  def remove(msg: Any): Unit = cache = cache - msg
  def contains(msg: Any): Boolean = cache.contains(msg)
}

object ActorCache {
  def apply(): ActorCache = new ActorCache()
}

// Settings
class ActorCacheSettings(config: Config) extends Extension {
  private val actorCacheConfig = config.getConfig("akka.actor.cache")
  val defaultTll =  Duration.fromNanos(actorCacheConfig.getDuration("default-ttl").toNanos)
}

object ActorCacheSettings extends ExtensionId[ActorCacheSettings] with ExtensionIdProvider {
  override def createExtension(system: ExtendedActorSystem): ActorCacheSettings = new ActorCacheSettings(system.settings.config)

  override def lookup(): ExtensionId[_ <: Extension] = ActorCacheSettings
}