在处理当前消息时，在akka中使用排队请求阻止其他参与者

Question

I have an actor with two types of messages, one for inserting to mysql and the other for inserting to redis. I wonder how block that redis actor with queuing the messages in that actor related to inserting in redis, while the mysql actor is processing.

@Override
public Receive createReceive() {
    return receiveBuilder()
            .match(RedisMessage.class, message -> {
                try {
                    accountService.saveBusinessAccountRedis(message.redisBusinessAccount);
                    getSender().tell(OK, getSelf());
                } catch (Exception e) {
                    //getSender().tell(new Status.Failure(e), getSelf());
                    e.printStackTrace();
                    //createRedisUser(idMessage.uid);
                    getSender().tell(NOK, getSelf());
                }

            }).match(MySqlMessage.class, message -> {
                try {
                    accountService.saveBusinessAccount();
                    //ToDo: test for queuing another actor! remove!! :)
                    Thread.sleep(300);
                    getSender().tell(OK, getSelf());
                } catch (Exception e) {
                    e.printStackTrace();
                    getSender().tell(NOK, getSelf());
                }

            }).build();
}


@Getter
@Setter
@AllArgsConstructor
public static class RedisMessage {
    private final RedisBusinessAccount redisBusinessAccount;
}

@Getter
@Setter
@AllArgsConstructor
public static class MySqlMessage {
    private final BusinessAccount businessAccount;
}

Answer 1

So what you want is you want to avoid processing RedisMessage s while you haven't yet received the response of the action triggered by MySqlMessage , right?

Do you want to be able to process multiple MySqlMessage s in the same actor? I suspect you do not.

I would suggest using become and 'stashing'. When processing a MySqlMessage , use become to move the actor to a state where it is 'waiting for the MySql result'. In that state, when you receive additional MySqlMessage or RedisMessage , you stash(msg) them. When you receive the OK or NOK from the MySQL call, you unstashAll() and use become to go back to the 'normal' state where you can start processing any (stashed or new) commands again.

Does that make sense?