Akka/Scala example source code file (SnapshotExample.scala)

This example Akka source code file (SnapshotExample.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Akka and Scala source code examples by using tags.

All credit for the original source code belongs to akka.io; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Akka tags/keywords

actor, actorsystem, akka, app, examplestate, list, nil, persistence, persistentactor, savesnapshotfailure, savesnapshotsuccess, snapshotexample, snapshotoffer, string

The SnapshotExample.scala Akka example source code

package sample.persistence

import akka.actor._
import akka.persistence._

object SnapshotExample extends App {
  final case class ExampleState(received: List[String] = Nil) {
    def updated(s: String): ExampleState = copy(s :: received)
    override def toString = received.reverse.toString
  }

  class ExamplePersistentActor extends PersistentActor {
    def persistenceId: String = "sample-id-3"

    var state = ExampleState()

    def receiveCommand: Actor.Receive = {
      case "print"                               => println("current state = " + state)
      case "snap"                                => saveSnapshot(state)
      case SaveSnapshotSuccess(metadata)         => // ...
      case SaveSnapshotFailure(metadata, reason) => // ...
      case s: String =>
        persist(s) { evt => state = state.updated(evt) }
    }

    def receiveRecover: Actor.Receive = {
      case SnapshotOffer(_, s: ExampleState) =>
        println("offered state = " + s)
        state = s
      case evt: String =>
        state = state.updated(evt)
    }

  }

  val system = ActorSystem("example")
  val persistentActor = system.actorOf(Props(classOf[ExamplePersistentActor]), "persistentActor-3-scala")

  persistentActor ! "a"
  persistentActor ! "b"
  persistentActor ! "snap"
  persistentActor ! "c"
  persistentActor ! "d"
  persistentActor ! "print"

  Thread.sleep(1000)
  system.shutdown()
}