add and verify Java API for actorFor/ActorPath, fixes #1343

akka-actor-tests/src/test/scala/akka/actor/ActorLookupSpec.scala

@@ -51,7 +51,11 @@ class ActorLookupSpec extends AkkaSpec with DefaultTimeout {
       system.actorFor(system / "c1") must be === c1
       system.actorFor(system / "c2") must be === c2
       system.actorFor(system / "c2" / "c21") must be === c21
+      system.actorFor(system child "c2" child "c21") must be === c21 // test Java API
       system.actorFor(system / Seq("c2", "c21")) must be === c21
+
+      import scala.collection.JavaConverters._
+      system.actorFor(system descendant Seq("c2", "c21").asJava) // test Java API
     }
 
     "find actors by looking up their string representation" in {
@@ -75,7 +79,7 @@ class ActorLookupSpec extends AkkaSpec with DefaultTimeout {
     "find actors by looking up their path elements" in {
       system.actorFor(c1.path.elements) must be === c1
       system.actorFor(c2.path.elements) must be === c2
-      system.actorFor(c21.path.elements) must be === c21
+      system.actorFor(c21.path.getElements) must be === c21 // test Java API
     }
 
     "find system-generated actors" in {
@@ -190,6 +194,8 @@ class ActorLookupSpec extends AkkaSpec with DefaultTimeout {
     }
 
     "return deadLetters for non-existing paths" in {
+      import scala.collection.JavaConverters._
+
       def checkOne(looker: ActorRef, query: Query) {
         (looker ? query).get must be === system.deadLetters
       }
@@ -198,6 +204,8 @@ class ActorLookupSpec extends AkkaSpec with DefaultTimeout {
           LookupString(""),
           LookupString("akka://all-systems/Nobody"),
           LookupPath(system / "hallo"),
+          LookupPath(looker.path child "hallo"), // test Java API
+          LookupPath(looker.path descendant Seq("a", "b").asJava), // test Java API
           LookupElems(Seq()),
           LookupElems(Seq("a"))) foreach (checkOne(looker, _))
       }

akka-actor/src/main/scala/akka/actor/ActorPath.scala

@@ -49,16 +49,37 @@ sealed trait ActorPath extends Comparable[ActorPath] {
    */
   def /(child: String): ActorPath
 
+  /**
+   * ''Java API'': Create a new child actor path.
+   */
+  def child(child: String): ActorPath = /(child)
+
   /**
    * Recursively create a descendant’s path by appending all child names.
    */
   def /(child: Iterable[String]): ActorPath = (this /: child)(_ / _)
 
   /**
-   * Sequence of names for this path. Performance implication: has to allocate a list.
+   * ''Java API'': Recursively create a descendant’s path by appending all child names.
+   */
+  def descendant(names: java.lang.Iterable[String]): ActorPath = {
+    import scala.collection.JavaConverters._
+    /(names.asScala)
+  }
+
+  /**
+   * Sequence of names for this path from root to this. Performance implication: has to allocate a list.
    */
   def elements: Iterable[String]
 
+  /**
+   * ''Java API'': Sequence of names for this path from root to this. Performance implication: has to allocate a list.
+   */
+  def getElements: java.lang.Iterable[String] = {
+    import scala.collection.JavaConverters._
+    elements.asJava
+  }
+
   /**
    * Walk up the tree to obtain and return the RootActorPath.
    */

akka-actor/src/main/scala/akka/actor/ActorRef.scala

@@ -178,7 +178,7 @@ private[akka] abstract class InternalActorRef extends ActorRef with ScalaActorRe
    * trailing "" element must be disregarded. If the requested path does not
    * exist, return Nobody.
    */
-  def getChild(name: Iterable[String]): InternalActorRef
+  def getChild(name: Iterator[String]): InternalActorRef
 }
 
 private[akka] case object Nobody extends MinimalActorRef {
@@ -256,26 +256,27 @@ class LocalActorRef private[akka] (
     }
   }
 
-  def getChild(names: Iterable[String]): InternalActorRef = {
+  def getChild(names: Iterator[String]): InternalActorRef = {
     /*
      * The idea is to recursively descend as far as possible with LocalActor
      * Refs and hand over to that “foreign” child when we encounter it.
      */
     @tailrec
-    def rec(ref: InternalActorRef, name: Iterable[String]): InternalActorRef = ref match {
-      case l: LocalActorRef ⇒
-        val n = name.head
-        val rest = name.tail
-        val next = n match {
-          case ".." ⇒ l.getParent
-          case ""   ⇒ l
-          case _    ⇒ l.getSingleChild(n)
-        }
-        if (next == Nobody || rest.isEmpty) next else rec(next, rest)
-      case _ ⇒
-        ref.getChild(name)
-    }
-    rec(this, names)
+    def rec(ref: InternalActorRef, name: Iterator[String]): InternalActorRef =
+      ref match {
+        case l: LocalActorRef ⇒
+          val n = name.next()
+          val next = n match {
+            case ".." ⇒ l.getParent
+            case ""   ⇒ l
+            case _    ⇒ l.getSingleChild(n)
+          }
+          if (next == Nobody || name.isEmpty) next else rec(next, name)
+        case _ ⇒
+          ref.getChild(name)
+      }
+    if (names.isEmpty) this
+    else rec(this, names)
   }
 
   // ========= AKKA PROTECTED FUNCTIONS =========
@@ -326,9 +327,11 @@ case class SerializedActorRef(path: String) {
 trait MinimalActorRef extends InternalActorRef {
 
   def getParent: InternalActorRef = Nobody
-  def getChild(name: Iterable[String]): InternalActorRef =
-    if (name.size == 1 && name.head.isEmpty) this
+  def getChild(names: Iterator[String]): InternalActorRef = {
+    val dropped = names.dropWhile(_.isEmpty)
+    if (dropped.isEmpty) this
     else Nobody
+  }
 
   //FIXME REMOVE THIS, ticket #1416
   //FIXME REMOVE THIS, ticket #1415

akka-actor/src/main/scala/akka/actor/ActorRefProvider.scala

@@ -287,7 +287,7 @@ trait ActorRefFactory {
   def actorFor(path: Iterable[String]): ActorRef = provider.actorFor(lookupRoot, path)
 
   /**
-   * Look-up an actor by applying the given path elements, starting from the
+   * ''Java API'': Look-up an actor by applying the given path elements, starting from the
    * current context, where `".."` signifies the parent of an actor.
    *
    * Example:
@@ -307,7 +307,7 @@ trait ActorRefFactory {
    *
    * For maximum performance use a collection with efficient head & tail operations.
    */
-  def actorFor(path: java.util.List[String]): ActorRef = {
+  def actorFor(path: java.lang.Iterable[String]): ActorRef = {
     import scala.collection.JavaConverters._
     provider.actorFor(lookupRoot, path.asScala)
   }
@@ -462,13 +462,17 @@ class LocalActorRefProvider(
     val children = new ConcurrentHashMap[String, AskActorRef]
     def path = tempNode
     override def getParent = rootGuardian
-    override def getChild(name: Iterable[String]): InternalActorRef = {
-      children.get(name.head) match {
-        case null ⇒ Nobody
-        case some ⇒
-          val t = name.tail
-          if (t.isEmpty) some
-          else some.getChild(t)
+    override def getChild(name: Iterator[String]): InternalActorRef = {
+      if (name.isEmpty) this
+      else {
+        val n = name.next()
+        if (n.isEmpty) this
+        else children.get(n) match {
+          case null ⇒ Nobody
+          case some ⇒
+            if (name.isEmpty) some
+            else some.getChild(name)
+        }
       }
     }
   }
@@ -497,7 +501,7 @@ class LocalActorRefProvider(
 
   def actorFor(ref: InternalActorRef, path: Iterable[String]): InternalActorRef =
     if (path.isEmpty) deadLetters
-    else ref.getChild(path) match {
+    else ref.getChild(path.iterator) match {
       case Nobody ⇒ deadLetters
       case x      ⇒ x
     }

akka-actor/src/main/scala/akka/actor/ActorSystem.scala

@@ -218,11 +218,24 @@ abstract class ActorSystem extends ActorRefFactory {
    */
   def /(name: String): ActorPath
 
+  /**
+   * ''Java API'': Create a new child actor path.
+   */
+  def child(child: String): ActorPath = /(child)
+
   /**
    * Construct a path below the application guardian to be used with [[ActorSystem.actorFor]].
    */
   def /(name: Iterable[String]): ActorPath
 
+  /**
+   * ''Java API'': Recursively create a descendant’s path by appending all child names.
+   */
+  def descendant(names: java.lang.Iterable[String]): ActorPath = {
+    import scala.collection.JavaConverters._
+    /(names.asScala)
+  }
+
   /**
    * Start-up time in milliseconds since the epoch.
    */

akka-remote/src/main/scala/akka/remote/RemoteActorRefProvider.scala

@@ -270,7 +270,7 @@ private[akka] case class RemoteActorRef private[akka] (
 
   // FIXME RK
   def getParent = Nobody
-  def getChild(name: Iterable[String]) = Nobody
+  def getChild(name: Iterator[String]) = Nobody
 
   @volatile
   private var running: Boolean = true