Thanks for the follow up -- the idea you posted is related, but not quite
it.
I wrote a self-contained working example below. What I do in this example
is manually materialize a graph, and wrap it as a future, making it usable
by mapAsync.
*Ideal: to define an entire graph such that the materialized subgraphs in
lineRewriter are instantiated and managed by akka itself.*
Can the code below be converted to do such a thing? (Scala responses also
great, but this happens to be java.)
b
---
// materialize entire subgraph as an async func
public static CompletionStage<String> lineRewriter(Materializer mat,
String line) {
return Source
.from(Arrays.asList(line.split(" "))) // unroll
.via(Flow.fromFunction(String::toUpperCase)) // per-item
processing
.runReduce((acc, w) -> acc + " " + w, mat); // rollup
}
public static void main(String[] args) {
final String batchesStr = "a word or two\nseparated by
newlines\nmakes for a simple\nstreaming batch test.";
final Source<String, NotUsed> batches =
Source.from(Arrays.asList(batchesStr.split("\n")));
final Sink<String, CompletionStage<Done>> printResp =
Sink.foreach(System.out::println);
batches.mapAsync(1, line -> lineRewriter(materializer,
line)).toMat(printResp, Keep.right())
.run(materializer)
.thenApply(d -> { system.terminate(); return d; })
.exceptionally(t -> { system.terminate(); return
Done.getInstance(); });
}
On Wednesday, May 10, 2017 at 1:53:43 PM UTC+2, Julian Howarth wrote:
>
> I may have misunderstood what you're trying to do but I think you can
> probably use expand for this. In builder pseudocode, something like:
>
> Flow ~> Unzip ~> <the processing you need producing n items> ~> Zip
> ~> Flow.expand(Iterator.continually(_)) ~>
>
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