02.Snapshots

@Component
@Scope("prototype")
public class SnapShotActor extends AbstractPersistentActor {
	
	private final LoggingAdapter log = Logging.getLogger(getContext().system(), "AbstractPersistentActor");	  
		
	private Object state;
	private int snapShotInterval = 5;
	
	private int msgCnt = 0;
	
    @Override
    public String persistenceId() { return "ExamplePersistentActor-id-1"; }
    
    @Override public Receive createReceiveRecover() {
	  return receiveBuilder().
	    match(SnapshotOffer.class, s -> {
	      state = s.snapshot();	//상태복원
	      log.info("상태복원");
	      // ...
	    }).
	    match(String.class, s -> {/* ...*/}).build();
	}
    
    @Override	//복구전략(스냅샷을 무시할수도 있음)
    public Recovery recovery() {
    	return Recovery.create(SnapshotSelectionCriteria.none());
    	/*
      return Recovery.create(
        SnapshotSelectionCriteria
          .create(457L, System.currentTimeMillis()));*/
    }
	 
	// 스냅샷을 지원하는 메시지 정의
	@Override public Receive createReceive() {
	  return receiveBuilder().
	    match(SaveSnapshotSuccess.class, ss -> {
	      SnapshotMetadata metadata = ss.metadata();	      
	      // ...
	    }).
	    match(SaveSnapshotFailure.class, sf -> {
	      SnapshotMetadata metadata = sf.metadata();
	      // ...
	    }).	      
	    match(String.class, cmd -> {
	    	log.info("EventFired:"+cmd);
	    	if(cmd.indexOf("print") ==0 ) {
	    		log.info("상태확인:"+state);	    		
	    	}else {
	    		msgCnt++;	    		
	    		state = cmd + "을 먹은 상태";		//커멘드에따른 상태변화	    		
	    		if (msgCnt % snapShotInterval == 0 ) {
		    		//이벤트가 ?회 발생할때만 스냅샷을 찍음 ( 스냅샵이 없을시 유실될수있습니다. )
		    		log.info("SaveSnapShot:" + state);
		    		saveSnapshot(state);	    		
		    	}	    		
	    	}
	    })	    
	    .build();
	}
}

private Object state;

@Override public Receive createReceiveRecover() {
  return receiveBuilder().
    match(SnapshotOffer.class, s -> {
      state = s.snapshot();
      // ...
    }).
    match(String.class, s -> {/* ...*/}).build();
}


또는


@Override
public Recovery recovery() {
  return Recovery.create(
    SnapshotSelectionCriteria
      .create(457L, System.currentTimeMillis()));
}

	protected void persistenceSnapShot()  {
	    new TestKit(system) {{
	    	ActorRef probe = getRef();	    	
	    	
			Props snapShotActorProp = ext.props("snapShotActor");			
			System.out.println("snapShotActor 액터생성");
			ActorRef snapShotActor = system.actorOf(snapShotActorProp, "snapShotActor");
			
			System.out.println("event 생성");
			snapShotActor.tell("커피", ActorRef.noSender());
			snapShotActor.tell("사탕", ActorRef.noSender());
			snapShotActor.tell("커피", ActorRef.noSender());
			snapShotActor.tell("스테이크", ActorRef.noSender());
			snapShotActor.tell("라면", ActorRef.noSender()); // <-- 복구기대 상태
			snapShotActor.tell("사탕", ActorRef.noSender());  
			snapShotActor.tell("커피", ActorRef.noSender());

			System.out.println("상태확인");
			snapShotActor.tell( "print" , ActorRef.noSender());			
			expectNoMessage(java.time.Duration.ofSeconds(1));
			
			System.out.println("snapShotActor 종료또는 비정상종료");
			snapShotActor.tell( akka.actor.PoisonPill.getInstance() , ActorRef.noSender());			
			expectNoMessage(java.time.Duration.ofSeconds(1));
			
			System.out.println("snapShotActor 마지막 상태 확인");
			ActorRef snapShotActo2 = system.actorOf(snapShotActorProp, "eventActor");
			
			System.out.println("상태 복원확인");
			snapShotActo2.tell( "print" , ActorRef.noSender());
			
			expectNoMessage(java.time.Duration.ofSeconds(1));				       
			
	    }};
	}