Merge pull request #19711 from johanandren/wip-19710-scala-types-attributes-java-api-johanandren

!str #19710 Use Java types in Attributes Java API

akka-stream-tests/src/test/java/akka/stream/javadsl/AttributesTest.java

@@ -7,6 +7,7 @@ import static org.junit.Assert.assertEquals;
 
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.Optional;
 
 import org.junit.ClassRule;
 import org.junit.Test;
@@ -47,4 +48,32 @@ public class AttributesTest extends StreamTest {
       attributes.getAttribute(Attributes.Name.class, new Attributes.Name("default")));
   }
 
+  @Test
+  public void mustGetMissingAttributeByClass() {
+    assertEquals(
+        Optional.empty(),
+        attributes.getAttribute(Attributes.LogLevels.class));
+  }
+
+  @Test
+  public void mustGetPossiblyMissingAttributeByClass() {
+    assertEquals(
+        Optional.of(new Attributes.Name("b")),
+        attributes.getAttribute(Attributes.Name.class));
+  }
+
+  @Test
+  public void mustGetPossiblyMissingFirstAttributeByClass() {
+    assertEquals(
+        Optional.of(new Attributes.Name("a")),
+        attributes.getFirstAttribute(Attributes.Name.class));
+  }
+
+  @Test
+  public void mustGetMissingFirstAttributeByClass() {
+    assertEquals(
+        Optional.empty(),
+        attributes.getFirstAttribute(Attributes.LogLevels.class));
+  }
+
 }

akka-stream-tests/src/test/scala/akka/stream/scaladsl/AttributesSpec.scala

@@ -60,6 +60,17 @@ class AttributesSpec extends AkkaSpec with ScalaFutures {
         attributes.get[Name] should contain(Name("attributesSink"))
       }
     }
+
+    val attributes = Attributes.name("a") and Attributes.name("b") and Attributes.inputBuffer(1, 2)
+
+    "give access to first attribute" in {
+      attributes.getFirst[Name] should ===(Some(Attributes.Name("a")))
+    }
+
+    "give access to attribute byt type" in {
+      attributes.get[Name] should ===(Some(Attributes.Name("b")))
+    }
+
   }
 
 }

akka-stream/src/main/scala/akka/stream/Attributes.scala

@@ -3,12 +3,15 @@
  */
 package akka.stream
 
+import java.util.Optional
+
 import akka.event.Logging
 import scala.annotation.tailrec
 import scala.reflect.{ classTag, ClassTag }
 import akka.japi.function
 import akka.stream.impl.StreamLayout._
 import java.net.URLEncoder
+import scala.compat.java8.OptionConverters._
 
 /**
  * Holds attributes which can be used to alter [[akka.stream.scaladsl.Flow]] / [[akka.stream.javadsl.Flow]]
@@ -48,32 +51,30 @@ final case class Attributes(attributeList: List[Attributes.Attribute] = Nil) {
    * If no such attribute exists the `default` value is returned.
    */
   def getAttribute[T <: Attribute](c: Class[T], default: T): T =
-    getAttribute(c) match {
-      case Some(a) ⇒ a
-      case None    ⇒ default
-    }
+    getAttribute(c).orElse(default)
 
   /**
    * Java API: Get the first (least specific) attribute of a given `Class` or subclass thereof.
    * If no such attribute exists the `default` value is returned.
    */
   def getFirstAttribute[T <: Attribute](c: Class[T], default: T): T =
-    getFirstAttribute(c) match {
-      case Some(a) ⇒ a
-      case None    ⇒ default
-    }
+    getFirstAttribute(c).orElse(default)
 
   /**
    * Java API: Get the last (most specific) attribute of a given `Class` or subclass thereof.
    */
-  def getAttribute[T <: Attribute](c: Class[T]): Option[T] =
-    Option(attributeList.foldLeft(null.asInstanceOf[T])((acc, attr) ⇒ if (c.isInstance(attr)) c.cast(attr) else acc))
+  def getAttribute[T <: Attribute](c: Class[T]): Optional[T] =
+    Optional.ofNullable(attributeList.foldLeft(
+      null.asInstanceOf[T]
+    )(
+      (acc, attr) ⇒ if (c.isInstance(attr)) c.cast(attr) else acc)
+    )
 
   /**
    * Java API: Get the first (least specific) attribute of a given `Class` or subclass thereof.
    */
-  def getFirstAttribute[T <: Attribute](c: Class[T]): Option[T] =
-    attributeList.find(c isInstance _).map(c cast _)
+  def getFirstAttribute[T <: Attribute](c: Class[T]): Optional[T] =
+    attributeList.collectFirst { case attr if c.isInstance(attr) => c cast attr }.asJava
 
   /**
    * Scala API: get all attributes of a given type (or subtypes thereof).
@@ -81,7 +82,7 @@ final case class Attributes(attributeList: List[Attributes.Attribute] = Nil) {
   def filtered[T <: Attribute: ClassTag]: List[T] = {
     val c = implicitly[ClassTag[T]].runtimeClass.asInstanceOf[Class[T]]
     attributeList.collect {
-      case a if c.isAssignableFrom(a.getClass) ⇒ c.cast(a)
+      case attr if c.isAssignableFrom(attr.getClass) ⇒ c.cast(attr)
     }
   }
 
@@ -102,14 +103,18 @@ final case class Attributes(attributeList: List[Attributes.Attribute] = Nil) {
   /**
    * Scala API: Get the last (most specific) attribute of a given type parameter T `Class` or subclass thereof.
    */
-  def get[T <: Attribute: ClassTag]: Option[T] =
-    getAttribute(classTag[T].runtimeClass.asInstanceOf[Class[T]])
+  def get[T <: Attribute: ClassTag]: Option[T] = {
+    val c = classTag[T].runtimeClass.asInstanceOf[Class[T]]
+    attributeList.reverseIterator.collectFirst[T] { case attr if c.isInstance(attr) => c.cast(attr) }
+  }
 
   /**
    * Scala API: Get the first (least specific) attribute of a given type parameter T `Class` or subclass thereof.
    */
-  def getFirst[T <: Attribute: ClassTag]: Option[T] =
-    getFirstAttribute(classTag[T].runtimeClass.asInstanceOf[Class[T]])
+  def getFirst[T <: Attribute: ClassTag]: Option[T] = {
+    val c = classTag[T].runtimeClass.asInstanceOf[Class[T]]
+    attributeList.collectFirst { case attr if c.isInstance(attr) => c.cast(attr) }
+  }
 
   /**
    * Test whether the given attribute is contained within this attributes list.

akka-stream/src/main/scala/akka/stream/impl/fusing/Ops.scala

@@ -445,7 +445,7 @@ private[akka] final case class Batch[In, Out](max: Long, costFn: In ⇒ Long, se
 
   override def createLogic(inheritedAttributes: Attributes): GraphStageLogic = new GraphStageLogic(shape) {
 
-    val decider = inheritedAttributes.getAttribute(classOf[SupervisionStrategy]).map(_.decider).getOrElse(Supervision.stoppingDecider)
+    val decider = inheritedAttributes.get[SupervisionStrategy].map(_.decider).getOrElse(Supervision.stoppingDecider)
 
     private var agg: Out = null.asInstanceOf[Out]
     private var left: Long = max
@@ -637,7 +637,7 @@ private[akka] final case class MapAsync[In, Out](parallelism: Int, f: In ⇒ Fut
     override def toString = s"MapAsync.Logic(buffer=$buffer)"
 
     //FIXME Put Supervision.stoppingDecider as a SupervisionStrategy on DefaultAttributes.mapAsync?
-    val decider = inheritedAttributes.getAttribute(classOf[SupervisionStrategy]).map(_.decider).getOrElse(Supervision.stoppingDecider)
+    val decider = inheritedAttributes.get[SupervisionStrategy].map(_.decider).getOrElse(Supervision.stoppingDecider)
 
     val buffer = new BoundedBuffer[Holder[Try[Out]]](parallelism)
     def todo = buffer.used
@@ -715,7 +715,7 @@ private[akka] final case class MapAsyncUnordered[In, Out](parallelism: Int, f: I
     override def toString = s"MapAsyncUnordered.Logic(inFlight=$inFlight, buffer=$buffer)"
 
     val decider =
-      inheritedAttributes.getAttribute(classOf[SupervisionStrategy])
+      inheritedAttributes.get[SupervisionStrategy]
         .map(_.decider).getOrElse(Supervision.stoppingDecider)
 
     var inFlight = 0
@@ -953,7 +953,7 @@ private[stream] final class Delay[T](d: FiniteDuration, strategy: DelayOverflowS
   override def initialAttributes: Attributes = DefaultAttributes.delay
   override def createLogic(inheritedAttributes: Attributes): GraphStageLogic = new TimerGraphStageLogic(shape) {
     val size =
-      inheritedAttributes.getAttribute(classOf[InputBuffer]) match {
+      inheritedAttributes.get[InputBuffer] match {
         case None                        ⇒ throw new IllegalStateException(s"Couldn't find InputBuffer Attribute for $this")
         case Some(InputBuffer(min, max)) ⇒ max
       }