Close Java Stream after completion #22241

akka-stream/src/main/scala/akka/stream/impl/JavaStreamSource.scala

@@ -0,0 +1,40 @@
+package akka.stream.impl
+
+import akka.stream._
+import akka.stream.stage.{ GraphStage, GraphStageLogic, OutHandler }
+import akka.annotation.InternalApi
+
+/** Internal API */
+@InternalApi
+private[stream] final class JavaStreamSource[T, S <: java.util.stream.BaseStream[T, S]](open: () ⇒ java.util.stream.BaseStream[T, S])
+  extends GraphStage[SourceShape[T]] {
+
+  val out: Outlet[T] = Outlet("JavaStreamSource")
+  override val shape: SourceShape[T] = SourceShape(out)
+
+  override def createLogic(inheritedAttributes: Attributes): GraphStageLogic =
+    new GraphStageLogic(shape) with OutHandler {
+      private[this] var stream: java.util.stream.BaseStream[T, S] = _
+      private[this] var iter: java.util.Iterator[T] = _
+
+      setHandler(out, this)
+
+      override def preStart(): Unit = {
+        stream = open()
+        iter = stream.iterator()
+      }
+
+      override def postStop(): Unit = {
+        if (stream ne null)
+          stream.close()
+      }
+
+      override def onPull(): Unit = {
+        if (iter.hasNext) {
+          push(out, iter.next())
+        } else {
+          complete(out)
+        }
+      }
+    }
+}