On Thursday, January 9, 2014 1:56:02 PM UTC+2, Tim Pigden wrote:
>
> 1. write your own fsm and embed it in an actor (it's not that hard. I
> wasted a quite a lot of time trying to bend the akka one to my purposes
> inappropriately before I realised this).
> 2. consider whether you are ever truly "active". After all you never had
> the opportunity to process messages in the active state. In which case
> shuffle the active transition processing into a separate method where you
> can access from either place. I'm not saying this is appropriate for you.
> 3. someone in scala-user suggested a self-message. Don't do that if
> there's a slightest change another message will arrive (or be in your input
> queue) otherwise it will be out of sequence. You might be able to
> circumvent this with some multi-actor explicit queue management but for me
> this was the first step in the slippery slope that led to wasted time and
> kept me away from realising that (1) was best for me.
>
Thanks Tim,
Yes, the actor should stay in Active, the transition from Waiting to
Expired being very infrequent, but it does happen.
I guess I'll write my own FSM :-)
>
> On Thursday, January 9, 2014 9:32:22 AM UTC, Alexandru Nedelcu wrote:
>>
>> Hi,
>>
>> I'm re-posting this from scala-user.
>>
>> I have a problem with FSM Actors in Akka. Say I have a bunch of states
>> and the transitions look something like this:
>>
>> Waiting -> Active -> Expired
>>
>> You can't get from Waiting to Expired directly. But when in "Waiting" I
>> still need to be able to send an "Expire" message to the actor, at which
>> point I need the actor to execute the transition changes for both (Waiting
>> -> Active) and for (Active -> Expired).
>>
>> So I basically want something like this (making stuff up):
>>
>>
>> when(Waiting) {
>> case Event(Expire, _) =>
>> goto(Active).andThen(Expired)
>> }
>>
>> onTransition {
>> case Waiting -> Active => /* activate */
>> case Active -> Expired => /* expiry */
>> }
>>
>> This is basically a non-deterministic finite automaton.
>>
>> Looking at the documentation and in the source-code, I don't believe this
>> is possible. It would have been great though, because the goto() on the
>> Expire event would make it perfectly clear that the actor first goes into
>> Active before being Expired. So what choices do I have?
>>
>> Thanks,
>>
>>
>>
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