f29d7affbd
* also make factories more consistent by only offering FlowGraph.create() * also remove secondary (edge-based) FlowGraph.Builder DSL * also improve naming for conversions from Graph to Source/Flow/BidiFlow/Sink
75 lines
2 KiB
Scala
75 lines
2 KiB
Scala
package docs.stream.cookbook
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import akka.stream.ClosedShape
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import akka.stream.scaladsl._
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import akka.stream.testkit._
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import akka.util.ByteString
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class RecipeKeepAlive extends RecipeSpec {
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"Recipe for injecting keepalive messages" must {
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"work" in {
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type Tick = Unit
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val tickPub = TestPublisher.probe[Tick]()
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val dataPub = TestPublisher.probe[ByteString]()
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val sub = TestSubscriber.manualProbe[ByteString]()
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val ticks = Source(tickPub)
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val dataStream = Source(dataPub)
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val keepaliveMessage = ByteString(11)
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val sink = Sink(sub)
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//#inject-keepalive
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val tickToKeepAlivePacket: Flow[Tick, ByteString, Unit] = Flow[Tick]
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.conflate(seed = (tick) => keepaliveMessage)((msg, newTick) => msg)
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val graph = RunnableGraph.fromGraph(FlowGraph.create() { implicit builder =>
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import FlowGraph.Implicits._
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val unfairMerge = builder.add(MergePreferred[ByteString](1))
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// If data is available then no keepalive is injected
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dataStream ~> unfairMerge.preferred
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ticks ~> tickToKeepAlivePacket ~> unfairMerge ~> sink
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ClosedShape
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})
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//#inject-keepalive
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graph.run()
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val subscription = sub.expectSubscription()
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tickPub.sendNext(())
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// pending data will overcome the keepalive
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dataPub.sendNext(ByteString(1))
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dataPub.sendNext(ByteString(2))
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dataPub.sendNext(ByteString(3))
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subscription.request(1)
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sub.expectNext(ByteString(1))
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subscription.request(2)
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sub.expectNext(ByteString(2))
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// This still gets through because there is some intrinsic fairness caused by the FIFO queue in the interpreter
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// Expecting here a preferred element also only worked true accident with the old Pump.
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sub.expectNext(keepaliveMessage)
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subscription.request(1)
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sub.expectNext(ByteString(3))
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subscription.request(1)
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tickPub.sendNext(())
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sub.expectNext(keepaliveMessage)
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dataPub.sendComplete()
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tickPub.sendComplete()
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sub.expectComplete()
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}
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}
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}
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