Akka and cake pattern

Question

I\'m confused how to ensure that my Actors have the appropriate dependencies using the cake pattern. I\'m still getting to grips with this, and I can\'t find any examples anywhe

Answer 1

Actors as dependency:

trait DBComponent {
   def db: ActorRef // no compile time guarantees

   type K
   type V

   object DBActor {
      case class Put(key: K, value: V)
      case class Get(key: K)
   }

   class DBActor {
      import DBActor._
      val db = scala.collection.mutable.Map.empty[K, V]
      def receive = {
         case Put(k, v) => db.put(k, v)
         case Get(k) => sender ! db.get(k)
      }
   }
}

trait ServiceComponent {
   this: DBComponent =>

   import DBActor._

   // you could be talking to deadLetters for all you know
   def put(k: K, v: V): Unit = db ! Put(k, v)
   def get(k: K): Option[V] = {
      implicit val timeout = Timeout(5 seconds)
      val future = ask(actor, Get(k)).mapTo[Option[V]]
      Await.result(future, timeout.duration)
   }
}

Actors having dependencies (where there is nothing special to it):

trait DBComponent {
   def db: DB

   type K
   type V

   trait DB {
      def put(key: K, value: V): Unit
      def get(key: K): Option[V]
   }
}

trait ServiceComponent {
   this: DBComponent =>

   object ServiceActor {
      case class Put(key: K, value: V)
      case class Get(key: K)
   }

   class ServiceActor {
      import ServiceActor._
      def receive = {
         case Put(k, v) => db.put(k, v) // db is in scope
         case Get(k) => sender ! db.get(k)
      }
   }
}