Hi, On Sat, Nov 28, 2015 at 1:42 AM, Harit Himanshu < [email protected]> wrote:
> Hello there, > > I am working on akka-persistence and my use case looks like following > > > - Jobs are submitted to PersistentActor, which are then journaled to > leveldb. I also maintain a state variable (as shown in the akka docs > <http://doc.akka.io/docs/akka/snapshot/scala/persistence.html>) > - There are worker actors who work on these jobs. > - Once worker completes the job successfully, I would like to remove > the job from leveldb and update the state variable. > > You will not be able to recover the state if your persistent actor crashes just after the state update. What is more, it seems that kafka storage backend <https://github.com/krasserm/akka-persistence-kafka/> is better suited for your usecase, which has a configurable retention time. > > I looked at the message deletion > <http://doc.akka.io/docs/akka/snapshot/scala/persistence.html#Message_deletion> > section, which has deleteMessages(toSequenceNr) API, but my confusion is > that I do not know the toSequenceNr. Infact, there may be many workers > working on different jobs at any time, and I want to remove a specific job > which is completed successfully. > > Once the message is deleted, I am ideally making this journal bounded > (otherwise it will increases forever). In this case, snapshots will be > smaller as well. > > How can I achieve this use case? Or am I not doing things right? > > My current code looks like > > import akka.actor.{Props, ActorSystem, ActorLogging} > import akka.event.LoggingReceive > import akka.persistence.{SaveSnapshotFailure, SaveSnapshotSuccess, > SnapshotOffer, PersistentActor} > > case class Command(data: String) > > case class Event(data: String) > > case object InternalState > > case object TakeSnapshot > > case object ShutDown > case object Fail > > case class State(queue: List[String] = Nil) { > def updated(event: Event): State = copy(event.data :: queue) > > def size: Int = queue.length > > override def toString: String = queue.reverse.toString > } > > class PersistentSnapshotActor extends PersistentActor with ActorLogging { > override def persistenceId = "snapshot-persistence-id" > > var state = State() > > def updateState(event: Event) = state = state.updated(event) > > def numberOfEvents = state.size > > def receiveRecover = LoggingReceive { > case event: Event => updateState(event) > case SnapshotOffer(_, snapshot: State) => > log.debug(s"offered state: $snapshot") > state = snapshot > } > > def receiveCommand = LoggingReceive { > case Command(data) => persist(Event(data))(updateState) > case Fail => throw new Exception("killing persistent actor.") > case ShutDown => context.stop(self) > case InternalState => println(state) > case TakeSnapshot => saveSnapshot(state) > delete > case SaveSnapshotSuccess => log.debug("snapshot saved successfully.") > case SaveSnapshotFailure(_, reason) => log.error(s"failed to save > snapshot: $reason") > } > } > > object PersistentSnapshotActorApp extends App { > val system = ActorSystem("snapshotSystem") > val persistentActor = system.actorOf(Props[PersistentSnapshotActor], > "persistentSnapshotActor") > > persistentActor ! Command("1") > persistentActor ! Command("2") > persistentActor ! Command("3") > persistentActor ! Command("4") > persistentActor ! TakeSnapshot > persistentActor ! InternalState > persistentActor ! Command("5") > persistentActor ! TakeSnapshot > persistentActor ! Fail > persistentActor ! InternalState > } > > Thanks a lot > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > -- Martynas Mickevičius Typesafe <http://typesafe.com/> – Reactive <http://www.reactivemanifesto.org/> Apps on the JVM -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.
