=jmh Add LazyFutureSourceBenchmark for #525.

Signed-off-by: He-Pin <hepin1989@gmail.com>

bench-jmh/src/main/scala/org/apache/pekko/stream/LazyFutureSourceBenchmark.scala

@@ -0,0 +1,77 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.pekko.stream
+
+import java.util.concurrent.TimeUnit
+
+import scala.concurrent._
+import scala.concurrent.duration._
+
+import com.typesafe.config.ConfigFactory
+import org.openjdk.jmh.annotations._
+
+import org.apache.pekko
+import pekko.NotUsed
+import pekko.actor.ActorSystem
+import pekko.stream.scaladsl._
+
+object LazyFutureSourceBenchmark {
+  final val OperationsPerInvocation = 100000
+}
+
+@State(Scope.Benchmark)
+@OutputTimeUnit(TimeUnit.SECONDS)
+@BenchmarkMode(Array(Mode.Throughput))
+class LazyFutureSourceBenchmark {
+  import LazyFutureSourceBenchmark._
+
+  private val config = ConfigFactory.parseString(
+    """
+  pekko.actor.default-dispatcher {
+    executor = "fork-join-executor"
+    fork-join-executor {
+      parallelism-factor = 1
+    }
+  }
+  """)
+
+  implicit val system: ActorSystem = ActorSystem("LazyFutureSourceBenchmark", config)
+
+  @TearDown
+  def shutdown(): Unit = {
+    Await.result(system.terminate(), 5.seconds)
+  }
+
+  private val newLazyFutureSource = Source.lazyFuture(() => Future.successful("")).toMat(Sink.ignore)(Keep.right)
+
+  private val create = () => Future.successful("")
+  private val oldLazyFutureSource = Source.lazySource { () =>
+    val f = create()
+    Source.future(f)
+  }.mapMaterializedValue(_ => NotUsed)
+
+  @Benchmark
+  @OperationsPerInvocation(OperationsPerInvocation)
+  def newLazyFuture(): Unit =
+    Await.result(newLazyFutureSource.run(), Duration.Inf)
+
+  @Benchmark
+  @OperationsPerInvocation(OperationsPerInvocation)
+  def oldLazyFuture(): Unit =
+    Await.result(oldLazyFutureSource.run(), Duration.Inf)
+}