57 lines
1.6 KiB
Scala
57 lines
1.6 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 topicMapper: (Message) => immutable.Seq[Topic] = { msg =>
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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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class X {
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//#multi-groupby
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val topicMapper: (Message) => immutable.Seq[Topic] = ???
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//#multi-groupby
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}
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//#multi-groupby
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val messageAndTopic: Source[(Message, Topic)] = 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: Source[(Topic, Source[String])] = messageAndTopic.groupBy(_._2).map {
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case (topic, topicStream) =>
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// chopping of the topic from the (Message, Topic) pairs
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(topic, topicStream.map(_._1))
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}
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//#multi-groupby
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val result = multiGroups.map {
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case (topic, topicMessages) => topicMessages.grouped(10).map(topic.name + _.mkString("[", ", ", "]")).runWith(Sink.head)
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}.mapAsync(identity).grouped(10).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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