=str #22448 rewrite Source.empty to GraphStage

akka-bench-jmh/src/main/scala/akka/stream/EmptySourceBenchmark.scala

@@ -0,0 +1,47 @@
+/**
+ * Copyright (C) 2014-2017 Lightbend Inc. <http://www.lightbend.com>
+ */
+
+package akka.stream
+
+import java.util.concurrent.TimeUnit
+
+import akka.actor.ActorSystem
+import akka.stream.scaladsl._
+import akka.{ Done, NotUsed }
+import org.openjdk.jmh.annotations._
+
+import scala.concurrent._
+import scala.concurrent.duration._
+
+@State(Scope.Benchmark)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@BenchmarkMode(Array(Mode.Throughput))
+class EmptySourceBenchmark {
+  implicit val system = ActorSystem("EmptySourceBenchmark")
+  val materializerSettings = ActorMaterializerSettings(system).withDispatcher("akka.test.stream-dispatcher")
+  implicit val materializer = ActorMaterializer(materializerSettings)
+
+
+  @TearDown
+  def shutdown(): Unit = {
+    Await.result(system.terminate(), 5.seconds)
+  }
+
+  val setup = Source.empty[String].toMat(Sink.ignore)(Keep.right)
+  
+  @Benchmark def empty(): Unit = 
+    Await.result(setup.run(), Duration.Inf)
+
+  
+  /*
+    (not serious benchmark, just sanity check: run on macbook 15, late 2013)
+  
+    While it was a PublisherSource:
+     [info] EmptySourceBenchmark.empty  thrpt   10  11.219 ± 6.498  ops/ms
+     
+    Rewrite to GraphStage:
+     [info] EmptySourceBenchmark.empty  thrpt   10  17.556 ± 2.865  ops/ms
+     
+   */
+}