public class ExampleDestinationAtLeastOnceDeliveryReceiveActor : ReceiveActor
{
    private ILoggingAdapter log = Context.GetLogger();
    protected int messageCnt = 0;
    public ExampleDestinationAtLeastOnceDeliveryReceiveActor()
    {
        Receive<Msg>(msg =>
        {
            messageCnt++;
            //Test를 위해 일부러 메시지를 못받은척한다.
            if (messageCnt % 2 ==0)
            {
                log.Warning("Test for Drop Message");
                return;
            }
                
            log.Debug("Yes I can");
            Sender.Tell(new Confirm(msg.DeliveryId), Self);
        });
    }
}


public class ExampleAtLeastOnceDeliveryReceiveActor : AtLeastOnceDeliveryReceiveActor
{
    private readonly IActorRef _destionationActor = Context.ActorOf<ExampleDestinationAtLeastOnceDeliveryReceiveActor>();
    private ILoggingAdapter log = Context.GetLogger();

    public ExampleAtLeastOnceDeliveryReceiveActor()
    {
        Recover<MsgSent>(msgSent => Handler(msgSent));
        Recover<MsgConfirmed>(msgConfirmed => Handler(msgConfirmed));

        Command<string>(str =>
        {
            log.Debug("received:" + str);
            Persist(new MsgSent(str), Handler);
        });

        Command<Confirm>(confirm =>
        {
            //메시지 받음을 확인하고, 해당 메시지를 더이상 안보낸다.
            log.Debug("received confirm:" + confirm.DeliveryId);
            Persist(new MsgConfirmed(confirm.DeliveryId), Handler);
        });
    }

    private void Handler(MsgSent msgSent)
    {
        Deliver(_destionationActor.Path, l => new Msg(l, msgSent.Message));
    }

    private void Handler(MsgConfirmed msgConfirmed)
    {
        ConfirmDelivery(msgConfirmed.DeliveryId);
    }

    public override string PersistenceId { get; } = "persistence-id";
}