1500d1f36d
A SubFlow (or SubSource) is not a Graph, it is an unfinished builder that accepts transformations. This allows us to capture the substreams’ transformations before materializing the flow, which will be very helpful in fully fusing all operators. Another change is that groupBy now requires a maxSubstreams parameter in order to bound its resource usage. In exchange the matching merge can be unbounded. This trades silent deadlock for explicit stream failure. This commit also changes all uses of Predef.identity to use `conforms` and removes the HTTP impl.util.identityFunc.
58 lines
1.5 KiB
Scala
58 lines
1.5 KiB
Scala
package docs.stream.cookbook
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import akka.stream.scaladsl.{ Sink, Source }
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import scala.collection.immutable
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import scala.concurrent.Await
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import scala.concurrent.duration._
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class RecipeMultiGroupBy extends RecipeSpec {
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"Recipe for multi-groupBy" must {
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"work" in {
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case class Topic(name: String)
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val elems = Source(List("1: a", "1: b", "all: c", "all: d", "1: e"))
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val extractTopics = { msg: Message =>
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if (msg.startsWith("1")) List(Topic("1"))
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else List(Topic("1"), Topic("2"))
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}
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//#multi-groupby
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val topicMapper: (Message) => immutable.Seq[Topic] = extractTopics
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val messageAndTopic: Source[(Message, Topic), Unit] = elems.mapConcat { msg: Message =>
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val topicsForMessage = topicMapper(msg)
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// Create a (Msg, Topic) pair for each of the topics
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// the message belongs to
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topicsForMessage.map(msg -> _)
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}
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val multiGroups = messageAndTopic
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.groupBy(2, _._2).map {
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case (msg, topic) =>
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// do what needs to be done
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//#multi-groupby
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(msg, topic)
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//#multi-groupby
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}
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//#multi-groupby
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val result = multiGroups
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.grouped(10)
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.mergeSubstreams
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.map(g => g.head._2.name + g.map(_._1).mkString("[", ", ", "]"))
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.grouped(10)
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.runWith(Sink.head)
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Await.result(result, 3.seconds).toSet should be(Set(
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"1[1: a, 1: b, all: c, all: d, 1: e]",
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"2[all: c, all: d]"))
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}
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}
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}
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