If that defer works as explained, then I can reduce my code to this:
...
val durables = events map { e ⇒
DurableEvent(e, pid).causedBy(cm)
}
persist(durables)(applyEvent)
defer()(_ ⇒ done)
...
That's rather nice :)
On Friday, July 17, 2015 at 8:04:54 PM UTC+1, ahjohannessen wrote:
>
> Andrew, I have also run into that and never paid much attention to defer,
> solved my problem in a rather clumsy way:
>
> private def processEvents(events: Seq[DomainEvent], cm: CommandMessage)(done:
> ⇒ Unit): Unit = {
>
> val durables = events map { e ⇒
> DurableEvent(e, pid).causedBy(cm)
> }
>
> if(durables.isEmpty) done else {
> val lastId = durables.last.eventId
> persist(durables) { pe ⇒
> applyEvent(pe)
> if(pe.eventId == lastId) done
> }
> }
> }
>
>
> On Friday, July 17, 2015 at 4:09:04 PM UTC+1, Andrew Easter wrote:
>>
>> Ah, thanks. I'd got confused and thought the defer behaviour was only
>> relevant when using persistAsync. Need to read the manual properly next
>> time, doh!
>>
>> On Friday, 17 July 2015 16:00:43 UTC+1, Ryan Bair wrote:
>>>
>>> Hi Andrew,
>>>
>>> There is the defer method which handles this case rather nicely.
>>>
>>> case Message =>
>>> val events = ...
>>> persist(events)
>>> defer() { _ => sender() ! Ack } // Not run until persist completes
>>>
>>> On Friday, July 17, 2015 at 10:47:01 AM UTC-4, Andrew Easter wrote:
>>>>
>>>> I've got a persistent actor that, on processing a command, generates
>>>> multiple events. There is support for persisting multiple events in the
>>>> API:
>>>>
>>>> def persist[A](events: immutable.Seq[A])(handler: A => Unit): Unit
>>>>
>>>> In my use case, after all the events have been persisted, I wish to
>>>> send an command acknowledgement to the sender:
>>>>
>>>> sender() ! Ack
>>>>
>>>> However, because the event handler is invoked per event, I can't easily
>>>> achieve invoking the sender acknowledgement only once all events have been
>>>> handled.
>>>>
>>>> Am I missing something obvious that would help serve my use case?
>>>>
>>>
--
>>>>>>>>>> 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
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