46 lines
1.4 KiB
Scala
46 lines
1.4 KiB
Scala
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/**
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* Copyright (C) 2016 Typesafe Inc. <http://www.typesafe.com>
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*/
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package docs.stream.cookbook
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import akka.stream.scaladsl._
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import scala.concurrent.Future
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import org.scalatest.concurrent.ScalaFutures
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import scala.concurrent.duration._
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class RecipeSeq extends RecipeSpec with ScalaFutures {
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implicit val patience = PatienceConfig(3.seconds)
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"Draining to a strict sequence" must {
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"not be done unsafely" in {
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val mySource = Source(1 to 3).map(_.toString)
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//#draining-to-seq-unsafe
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// Dangerous: might produce a collection with 2 billion elements!
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val f: Future[Seq[String]] = mySource.runWith(Sink.seq)
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//#draining-to-seq-unsafe
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f.futureValue should ===(Seq("1", "2", "3"))
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}
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"be done safely" in {
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val mySource = Source(1 to 3).map(_.toString)
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//#draining-to-seq-safe
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val MAX_ALLOWED_SIZE = 100
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// OK. Future will fail with a `StreamLimitReachedException`
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// if the number of incoming elements is larger than max
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val limited: Future[Seq[String]] =
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mySource.limit(MAX_ALLOWED_SIZE).runWith(Sink.seq)
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// OK. Collect up until max-th elements only, then cancel upstream
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val ignoreOverflow: Future[Seq[String]] =
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mySource.take(MAX_ALLOWED_SIZE).runWith(Sink.seq)
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//#draining-to-seq-safe
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limited.futureValue should ===(Seq("1", "2", "3"))
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ignoreOverflow.futureValue should ===(Seq("1", "2", "3"))
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}
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}
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}
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