A solution like this could work, but it is a lot more complicated (complexity added just to handle actor termination).

The databaseServer actor is not affected by the deaths of the indexes.

Btw, all my Terminated actors are local (same ActorSystem, same jvm) to the watcher, does that help?

On 09/10/15 17:36, Michael Frank wrote:
instead of using actor paths to send directly to the index actor, why not send your message to the /databaseServer actor, which then forwards the message to the appropriate index actor? the databaseServer actor would contain a Map[String,ActorRef] which maps index name to index actor (which are its children), and would register deathwatch on each child, so it would be notified when an index goes away and update its state.

-Michael

On 10/09/15 08:58, 'Konstantinos Kougios' via Akka User List wrote:
well, I am using actor paths to find the actors, which are unique per ActorSystem.

I.e. paths are

../databaseServer

../databaseServer/index:x1

../databaseServer/index:x2

I am using the akka cluster, so each "server" will have these paths.

Now when I do a "dropIndex" and drop index x1, actors ../databaseServer/index:x1 on each server must terminate. I would like to know precisely when that occurred, because a drop/recreate will have the issue of the same actor name.

Now I could, for tests, use a unique index name each time. But some tests need to drop/recreate the /databaseServer (and remember I refer to the indexes by ../databaseServer/index:x1)

Cheers


On 09/10/15 12:30, Patrik Nordwall wrote:
it's probably easies to not reuse the name

On Fri, Oct 9, 2015 at 1:23 PM, 'Konstantinos Kougios' via Akka User List <[email protected]> wrote:

    Well, I have this component based on 1 actor. It is the "flow"
    thing I was talking a few months ago, anyway it does take care
    of a process between different actors. One thing it does is to
    stop an other actor and wait till it is terminated. I need to
    make sure the other actor is really terminated because further
    down an actor with the same name is created - which randomly &
    rarely fails with "actor name [databaseServer] is not unique!"


    On 09/10/15 12:17, Patrik Nordwall wrote:


    On Fri, Oct 9, 2015 at 12:59 PM, 'Konstantinos Kougios' via
    Akka User List <[email protected]> wrote:

        oh... in that case my code changes won't work. The watcher
        is not the parent of the actor.

        Will it work if the watcher is child of the same parent of
        the Terminated actor?


    no, but what would a sibling do? it can't recreate the actor,
    it is only the parent that can create child actor with same name




        On 09/10/15 06:08, Patrik Nordwall wrote:
        Note that this advice is correct but only when the parent
        actor receives the Terminated, i.e. it does not hold for
        top level actors where you can only watch from the "outside".
        tors 8 okt. 2015 kl. 11:46 skrev Kostas kougios
        <[email protected]
        <mailto:[email protected]>>:

            Thanks, I am doing that now and hopefully it works
            (the issue occurred very rarely, so I have to wait and
            see)


            On Friday, 2 October 2015 17:16:35 UTC+1, Ryan Tanner
            wrote:

                Don't create the replacement actor until you've
                received a Terminated message for the original actor.

                On Friday, October 2, 2015 at 8:58:54 AM UTC-6,
                Kostas kougios wrote:

                    I create a named actor, stop it and recreate
                    it with the same name. Because stop is async,
                    I end up with exceptions like

                    akka.actor.InvalidActorNameException: actor
                    name [databaseServer] is not unique!
                    [info]   at
                    
akka.actor.dungeon.ChildrenContainer$NormalChildrenContainer.reserve(ChildrenContainer.scala:130)
                    [info]   at
                    
akka.actor.dungeon.Children$class.reserveChild(Children.scala:77)
                    [info]   at
                    akka.actor.ActorCell.reserveChild(ActorCell.scala:373)
                    [info]   at
                    
akka.actor.dungeon.Children$class.makeChild(Children.scala:215)
                    [info]   at
                    
akka.actor.dungeon.Children$class.attachChild(Children.scala:42)
                    [info]   at
                    akka.actor.ActorCell.attachChild(ActorCell.scala:373)
                    [info]   at
                    akka.actor.ActorSystemImpl.actorOf(ActorSystem.scala:586)
                    [info]   at
                    
org.distributedrange.actors.StreamActor$$anonfun$2.apply(StreamActor.scala:122)

                    I get the same exception even if I set an
                    AtomicBoolean to true at:

                    override def postStop() = {
                        stopped.set(true)
                        super.postStop()
                    }


                    and then

                    while (!stopped.get) {
                        Thread.sleep(1)
                      }


                    Is there a way to "block" and wait till the
                    actor stops?
                    (don't worry about the block part, it is only
                    for test cases)

                    Thanks

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