Thanks Rafal.
Based on this I tried to make sample code, where I would like to count
number of elements being processed and their sum:
val source = Source (1 to 5).filter(x=> x%2==0)
val sink:Sink[Int, Future[Int]]=Sink.fold[Int,Int](0)(_ + _)
val runnableGraph = source.via(counter[Int]).toMat(sink)(Keep.both)
val result=runnableGraph.run()
def counter[T]: Flow[T, T, Counter] = {
val internalCounter = new AtomicLong(0)
Flow[T].map{ elem ⇒
internalCounter.incrementAndGet()
elem
}.mapMaterializedValue(_ ⇒ new Counter{
override def get = internalCounter.get
})
}
1. using Keep.both, result should able to return me count and sum, but it is
not?
2. How materialize values are different than "out"? I am not able to visualize
the difference between materialize values and out?
Thanks
Arun
On Saturday, March 5, 2016 at 6:02:56 PM UTC-6, Arun Sethia wrote:
>
> Hi,
>
> can some explain what does it mean of materialized value ? I have see
> documentation at
> http://doc.akka.io/docs/akka-stream-and-http-experimental/2.0.3/scala/stream-quickstart.html#transforming-and-consuming-simple-streams
>
>
> I am not sure how Flow can define materialize type, for example the
> following code has Input - Tweet, output - Int but Mat is Unit. I would
> like to see how someone can define Mat as Int or any example where Flow or
> source is defining Mat other than Unit.
>
> - val count: Flow[Tweet, Int, Unit] = Flow[Tweet].map(_ => 1)
>
>
>
> It is quite confusing for me to understand difference between "out" and
> "Mat".
>
>
> Thanks
>
> As
>
>
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