+doc #19429 initial merge of docs-dev and docs

akka-docs/rst/scala/code/docs/stream/StreamBuffersRateSpec.scala

@@ -0,0 +1,89 @@
+package docs.stream
+
+import akka.stream._
+import akka.stream.scaladsl._
+import akka.stream.testkit.AkkaSpec
+
+class StreamBuffersRateSpec extends AkkaSpec {
+  implicit val materializer = ActorMaterializer()
+
+  "Demonstrate pipelining" in {
+    def println(s: Any) = ()
+    //#pipelining
+    Source(1 to 3)
+      .map { i => println(s"A: $i"); i }
+      .map { i => println(s"B: $i"); i }
+      .map { i => println(s"C: $i"); i }
+      .runWith(Sink.ignore)
+    //#pipelining
+  }
+
+  "Demonstrate buffer sizes" in {
+    //#materializer-buffer
+    val materializer = ActorMaterializer(
+      ActorMaterializerSettings(system)
+        .withInputBuffer(
+          initialSize = 64,
+          maxSize = 64))
+    //#materializer-buffer
+
+    //#section-buffer
+    val section = Flow[Int].map(_ * 2)
+      .withAttributes(Attributes.inputBuffer(initial = 1, max = 1))
+    val flow = section.via(Flow[Int].map(_ / 2)) // the buffer size of this map is the default
+    //#section-buffer
+  }
+
+  "buffering abstraction leak" in {
+    //#buffering-abstraction-leak
+    import scala.concurrent.duration._
+    case class Tick()
+
+    RunnableGraph.fromGraph(GraphDSL.create() { implicit b =>
+      import GraphDSL.Implicits._
+
+      val zipper = b.add(ZipWith[Tick, Int, Int]((tick, count) => count))
+
+      Source.tick(initialDelay = 3.second, interval = 3.second, Tick()) ~> zipper.in0
+
+      Source.tick(initialDelay = 1.second, interval = 1.second, "message!")
+        .conflate(seed = (_) => 1)((count, _) => count + 1) ~> zipper.in1
+
+      zipper.out ~> Sink.foreach(println)
+      ClosedShape
+    })
+    //#buffering-abstraction-leak
+  }
+
+  "explcit buffers" in {
+    trait Job
+    def inboundJobsConnector(): Source[Job, Unit] = Source.empty
+    //#explicit-buffers-backpressure
+    // Getting a stream of jobs from an imaginary external system as a Source
+    val jobs: Source[Job, Unit] = inboundJobsConnector()
+    jobs.buffer(1000, OverflowStrategy.backpressure)
+    //#explicit-buffers-backpressure
+
+    //#explicit-buffers-droptail
+    jobs.buffer(1000, OverflowStrategy.dropTail)
+    //#explicit-buffers-droptail
+
+    //#explicit-buffers-dropnew
+    jobs.buffer(1000, OverflowStrategy.dropNew)
+    //#explicit-buffers-dropnew
+
+    //#explicit-buffers-drophead
+    jobs.buffer(1000, OverflowStrategy.dropHead)
+    //#explicit-buffers-drophead
+
+    //#explicit-buffers-dropbuffer
+    jobs.buffer(1000, OverflowStrategy.dropBuffer)
+    //#explicit-buffers-dropbuffer
+
+    //#explicit-buffers-fail
+    jobs.buffer(1000, OverflowStrategy.fail)
+    //#explicit-buffers-fail
+
+  }
+
+}