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 ) {
	    		//로그를 통해 확인하거나?
	    		log.info("상태확인:"+state);
	    		// 전송자에게 메시지를 통해 상태를 알려줌
	    		sender().tell(state, ActorRef.noSender());	    		
	    	}else {
	    		msgCnt++;	    		
	    		state = cmd + "을 먹은 상태";		//커멘드에따른 상태변화
	    		log.info("ChangeStated" + state);
	    		
	    		if (msgCnt % snapShotInterval == 0 ) {
		    		//이벤트가 ?회 발생할때만,상태를 변경하고 스냅샷을 찍음 ( 순수스냅샷 테스트 )	        		        	  		    				    		
		    		log.info("SaveSnapShot:" + state);
		    		saveSnapshot(state);	    		
		    	}	    		
	    	}
	    })	    
	    .build();
	}
}

@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 재생성");
		ActorRef snapShotActo2 = system.actorOf(snapShotActorProp, "eventActor");
		
		System.out.println("=====  상태 복원확인을 위해 probe를 액터 참조자로 지정");
		snapShotActo2.tell( "print" , probe );
		
		// === 기대결과 1초이내에 '라면을 먹은 상태'임을 확인 : 비동기 메시지를 검사하는방법중하나  
		expectMsgEquals(java.time.Duration.ofSeconds(1), "라면을 먹은 상태" );			
    }};
}