how can I verify that the persistence process is completed in order to gracefully shutdown the system?

Question

using akka actor - I am sending heavy rate of messages to the actor that updates it's state

for (i <-0 to 100000){
  persistentActor ! Cmd("foo"+i)
}

and using the persistAsync like this

 val receiveCommand: Receive = {
    case Cmd(data) =>
      persistAsync(Evt(s"${data}-${numEvents}"))(updateState)
    case "snap"  => saveSnapshot(state)
    case "print" => println(state)
  }

how can I verify that the persistence process is completed in order to gracefully shutdown the system ?

Answer 1

Your actor will receive acknowledge after snapshot's persistence:

 var count = 0
 var shutdown = false
 def checkShutDown() = if (shutdown && count == 0) context stop self

 def receive = {
     case "snap"  => count++; saveSnapshot(state)
     case SaveSnapshotSuccess(metadata)         =>
         count --; checkShutDown()
     case SaveSnapshotFailure(metadata, reason)  =>
         count --; checkShutDown()
     case ShutDown => 
         shutdown = true; checkShutDown()
 }

And finally you could use The Reaper pattern to shutdown your system after actors shutdown.