review comments

- some API docs
- require names for top-level actors
- allow names for children
- flag error when no channels declared

akka-actor/src/main/scala/akka/dispatch/Future.scala

@@ -70,8 +70,8 @@ object ExecutionContexts {
    * It is very useful for actions which are known to be non-blocking and
    * non-throwing in order to save a round-trip to the thread pool.
    */
-  object sameThreadExecutionContext extends ExecutionContext {
+  private[akka] object sameThreadExecutionContext extends ExecutionContext with BatchingExecutor {
-    override def execute(runnable: Runnable): Unit = runnable.run()
+    override protected def unbatchedExecute(runnable: Runnable): Unit = runnable.run()
     override def reportFailure(t: Throwable): Unit =
       throw new IllegalStateException("exception in sameThreadExecutionContext", t)
   }

akka-channels-tests/src/test/scala/akka/channels/ChannelSpec.scala

@@ -126,7 +126,7 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
   "Actor with Channels" must {
 
     "construct refs" in {
-      val ref = ChannelExt(system).actorOf(new Tester)
+      val ref = ChannelExt(system).actorOf(new Tester, "t1")
       ref <-!- A
       expectMsg(C)
       lastSender must be(ref.actorRef)
@@ -136,16 +136,16 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
     }
 
     "select return channels" in {
-      val ref = ChannelExt(system).actorOf(new Tester)
+      val ref = ChannelExt(system).actorOf(new Tester, "t2")
-      implicit val selfChannel = ChannelExt(system).actorOf(new RecvC(testActor))
+      implicit val selfChannel = ChannelExt(system).actorOf(new RecvC(testActor), "t3")
       ref <-!- A
       expectMsg(C)
       lastSender must be(selfChannel.actorRef)
     }
 
     "correctly dispatch to subchannels" in {
-      val ref = ChannelExt(system).actorOf(new Tester)
+      val ref = ChannelExt(system).actorOf(new Tester, "t4")
-      implicit val selfChannel = ChannelExt(system).actorOf(new RecvC(testActor))
+      implicit val selfChannel = ChannelExt(system).actorOf(new RecvC(testActor), "t5")
       ref <-!- A2
       expectMsg(C1)
       lastSender must be(selfChannel.actorRef)
@@ -281,7 +281,7 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
     }
 
     "have a working selfChannel" in {
-      val ref = ChannelExt(system).actorOf(new Children)
+      val ref = ChannelExt(system).actorOf(new Children, "t10")
       ref <-!- A
       expectMsg(C)
     }
@@ -292,7 +292,7 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
           parentChannel <-!- A
         })
         channel[A] { (msg, snd) ⇒ testActor ! msg }
-      })
+      }, "t11")
       expectMsg(A)
     }
 
@@ -301,7 +301,7 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
         eval("""
             |import akka.channels._
             |import ChannelSpec._
-            |null.asInstanceOf[ChannelExtension].actorOf(new Actor with Channels[(A, A) :+: TNil, (A, Nothing) :+: TNil] {})
+            |null.asInstanceOf[ChannelExtension].actorOf(new Actor with Channels[(A, A) :+: TNil, (A, Nothing) :+: TNil] {}, "")
             """.stripMargin)
       }.message must include("type mismatch")
     }
@@ -367,7 +367,7 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
 
     "support narrowing ActorRefs" in {
       import Channels._
-      val channel = ChannelExt(system).actorOf(new RecvC(testActor))
+      val channel = ChannelExt(system).actorOf(new RecvC(testActor), "t15")
       val ref = channel.actorRef
       implicit val t = Timeout(1.second.dilated)
       import system.dispatcher
@@ -377,7 +377,7 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
     }
 
     "deny wrong narrowing of ActorRefs" in {
-      val channel = ChannelExt(system).actorOf(new RecvC(testActor))
+      val channel = ChannelExt(system).actorOf(new RecvC(testActor), "t16")
       val ref = channel.actorRef
       implicit val t = Timeout(1.second.dilated)
       import system.dispatcher
@@ -392,8 +392,8 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
     }
 
     "allow wrapping of ChannelRefs with pass-through" in {
-      val target = ChannelExt(system).actorOf(new RecvC(testActor))
+      val target = ChannelExt(system).actorOf(new RecvC(testActor), "t17")
-      val wrap = ChannelExt(system).actorOf(new WriteOnly[C, Nothing](target))
+      val wrap = ChannelExt(system).actorOf(new WriteOnly[C, Nothing](target), "t18")
       wrap <-!- C
       expectMsg(C)
       lastSender must be(target.actorRef)
@@ -404,8 +404,8 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
 
     "allow wrapping of Actor with ChannelsRefs with replies" in {
       val probe = TestProbe()
-      val target = ChannelExt(system).actorOf(new EchoTee(probe.ref))
+      val target = ChannelExt(system).actorOf(new EchoTee(probe.ref), "t19")
-      val wrap = ChannelExt(system).actorOf(new WriteOnly[C, C](target))
+      val wrap = ChannelExt(system).actorOf(new WriteOnly[C, C](target), "t20")
       C -!-> wrap
       expectMsg(C1)
       expectMsg(C1)
@@ -413,14 +413,14 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
     }
 
     "support typed ask" in {
-      val t = ChannelExt(system).actorOf(new Tester)
+      val t = ChannelExt(system).actorOf(new Tester, "t21")
       implicit val timeout = Timeout(1.second)
       val r: Future[C] = (t <-?- A).lub
       Await.result(r, 1.second) must be(C)
     }
 
     "support typed ask with multiple reply channels" in {
-      val t = ChannelExt(system).actorOf(new SubChannels)
+      val t = ChannelExt(system).actorOf(new SubChannels, "t22")
       implicit val timeout = Timeout(1.second)
       val r: Future[Msg] = (t <-?- A1).lub
       Await.result(r, 1.second) must be(B)
@@ -462,8 +462,8 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
     "be able to forward fully generic channels" in {
       val cd = ChannelExt(system).actorOf(new Actor with Channels[TNil, (C, D) :+: TNil] {
         channel[C] { (x, snd) ⇒ snd <-!- D }
-      })
+      }, "t25")
-      val t = ChannelExt(system).actorOf(new Poly(cd))
+      val t = ChannelExt(system).actorOf(new Poly(cd), "t26")
       t <-!- A
       expectMsg(A)
       t <-!- C
@@ -479,8 +479,8 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
       implicit val selfChannel = ChannelExt(system).actorOf(new Actor with Channels[TNil, (C, Nothing) :+:(D, Nothing) :+: TNil] {
         channel[C] { (c, snd) ⇒ testActor ! c }
         channel[D] { (d, snd) ⇒ testActor ! d }
-      })
+      }, "t27")
-      val t = ChannelExt(system).actorOf(new Tester)
+      val t = ChannelExt(system).actorOf(new Tester, "t28")
       val a = new WrappedMessage[(A, Nothing) :+:(B, Nothing) :+: TNil, Msg](A)
       val fa = Future successful a
       val b = new WrappedMessage[(A, Nothing) :+:(B, Nothing) :+: TNil, Msg](B)
@@ -548,7 +548,7 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
 
     "be askable to a ChannelRef" in {
       implicit val timeout = Timeout(1.second)
-      val t = ChannelExt(system).actorOf(new Tester)
+      val t = ChannelExt(system).actorOf(new Tester, "t30")
       val a = new WrappedMessage[(A, Nothing) :+:(B, Nothing) :+: TNil, Msg](A)
       val fa = Future successful a
       val b = new WrappedMessage[(A, Nothing) :+:(B, Nothing) :+: TNil, Msg](B)
@@ -608,7 +608,7 @@ class ChannelSpec extends AkkaSpec(ActorSystem("ChannelSpec", AkkaSpec.testConf,
 
     "be LUBbable within a Future" in {
       implicit val timeout = Timeout(1.second)
-      val t = ChannelExt(system).actorOf(new Tester)
+      val t = ChannelExt(system).actorOf(new Tester, "t31")
       val a = new WrappedMessage[(A, Nothing) :+:(B, Nothing) :+: TNil, Msg](A)
       (Await.result((a -?-> t).lub, timeout.duration): Msg) must be(C)
     }

akka-channels/src/main/scala/akka/channels/ChannelExtension.scala

@@ -17,9 +17,10 @@ object ChannelExt extends ExtensionKey[ChannelExtension]
 
 class ChannelExtension(system: ExtendedActorSystem) extends Extension {
 
-  // kick-start the universe (needed due to thread safety issues in runtime mirror)
+  // FIXME: kick-start the universe (needed due to thread safety issues in runtime mirror)
+  // see https://issues.scala-lang.org/browse/SI-6240
   private val t = typeTag[(Int, Int) :+: TNil]
 
-  def actorOf[Ch <: ChannelList](factory: ⇒ Actor with Channels[TNil, Ch]): ChannelRef[Ch] =
+  def actorOf[Ch <: ChannelList](factory: ⇒ Actor with Channels[TNil, Ch], name: String): ChannelRef[Ch] =
-    new ChannelRef[Ch](system.actorOf(Props(factory)))
+    new ChannelRef[Ch](system.actorOf(Props(factory), name))
 }

akka-channels/src/main/scala/akka/channels/ChannelRef.scala

@@ -6,27 +6,38 @@ package akka.channels
 
 import language.experimental.{ macros ⇒ makkros }
 import akka.actor.ActorRef
-import scala.reflect.runtime.universe.TypeTag
-import scala.reflect.macros.Context
-import scala.annotation.tailrec
-import scala.reflect.macros.Universe
-import akka.actor.Actor
-import akka.actor.ActorContext
 import scala.concurrent.Future
-import akka.util.Timeout
-import akka.AkkaException
-import scala.util.control.NoStackTrace
-
-case class NarrowingException(errors: String) extends AkkaException(errors) with NoStackTrace
 
+/**
+ * A channel reference, holding a type list of all channels supported by the
+ * underlying actor. This actor’s reference can be obtained as the `actorRef`
+ * member.
+ */
 class ChannelRef[+T <: ChannelList](val actorRef: ActorRef) extends AnyVal {
 
+  /**
+   * Send a message over this channel, “tell” semantics, returning the message.
+   */
   def <-!-[M](msg: M): M = macro macros.Tell.impl[T, M]
 
+  /**
+   * Eventually send the value contained in the future over this channel,
+   * “tell” semantics, returning a Future which is completed after sending
+   * with the value which was sent (“Future.andThen” semantics).
+   */
   def <-!-[M](future: Future[M]): Future[M] = macro macros.Tell.futureImpl[T, M]
 
+  /**
+   * Send a message over this channel, “ask” semantics, returning a Future
+   * which will be completed with the reply message or a TimeoutException.
+   * If the message is a Future itself, eventually send the Future’s value.
+   */
   def <-?-[M](msg: M): Future[_] = macro macros.Ask.impl[ChannelList, Any, T, M]
 
+  /**
+   * Narrow this ChannelRef by removing channels or narrowing input types or
+   * widening output types.
+   */
   def narrow[C <: ChannelList]: ChannelRef[C] = macro macros.Narrow.impl[C, T]
 
 }

akka-channels/src/main/scala/akka/channels/Channels.scala

@@ -51,6 +51,13 @@ trait Channels[P <: ChannelList, C <: ChannelList] { this: Actor ⇒
    */
   def createChild[Pa <: ChannelList, Ch <: ChannelList](factory: Actor with Channels[Pa, Ch]): ChannelRef[Ch] = macro macros.CreateChild.impl[C, Pa, Ch]
 
+  /**
+   * Create a child actor with properly typed ChannelRef and the given name,
+   * verifying that this actor can handle everything which the child tries to
+   * send via its `parent` ChannelRef.
+   */
+  def createChild[Pa <: ChannelList, Ch <: ChannelList](factory: Actor with Channels[Pa, Ch], name: String): ChannelRef[Ch] = macro macros.CreateChild.implName[C, Pa, Ch]
+
   /**
    * Properly typed ChannelRef for the context.parent.
    */
@@ -131,6 +138,8 @@ trait Channels[P <: ChannelList, C <: ChannelList] { this: Actor ⇒
 
     private def verifyCompleteness() {
       val channels = inputChannels(ru)(channelListTypeTag.tpe)
+      if (channels.isEmpty)
+        throw ActorInitializationException("Actor with Channels cannot have no channels")
       val classes = channels groupBy (e ⇒ channelListTypeTag.mirror.runtimeClass(e.widen))
       val missing = classes.keySet -- behavior.keySet
       if (missing.nonEmpty) {
@@ -162,10 +171,7 @@ trait Channels[P <: ChannelList, C <: ChannelList] { this: Actor ⇒
       case c: CheckType[_] ⇒ true
       case _ ⇒
         val msgClass = x.getClass
-        index find (_ isAssignableFrom msgClass) match {
+        index exists (_ isAssignableFrom msgClass)
-          case None      ⇒ false
-          case Some(cls) ⇒ true
-        }
     }
   }
 }

akka-channels/src/main/scala/akka/channels/Ops.scala

@@ -12,6 +12,7 @@ import scala.concurrent.{ ExecutionContext, Future }
 import scala.reflect.runtime.{ universe ⇒ ru }
 import scala.util.Success
 import akka.dispatch.ExecutionContexts
+import scala.util.control.NoStackTrace
 
 sealed trait ChannelList
 sealed trait TNil extends ChannelList
@@ -26,8 +27,23 @@ sealed trait ReplyChannels[T <: ChannelList] extends ChannelList
  */
 sealed trait UnknownDoNotWriteMeDown
 
+/**
+ * This exception is used to signal errors when trying to `.narrow` an
+ * ActorRef into a ChannelRef: if the actor finds the requested channel types
+ * incompatible with its selfChannel, it will return errors in the same format
+ * as would occur during compilation of a `ChannelRef.narrow` operation.
+ */
+case class NarrowingException(message: String) extends akka.AkkaException(message) with NoStackTrace
+
 class ActorRefOps(val ref: ActorRef) extends AnyVal {
   import macros.Helpers._
+
+  /**
+   * Send a query to the actor and check whether it supports the requested
+   * channel types; the normal timeout semantics of the `ask` pattern apply.
+   * The Future will be completed either with the desired ChannelRef or with
+   * an exception (TimeoutException or NarrowingException).
+   */
   def narrow[C <: ChannelList](implicit timeout: Timeout, ec: ExecutionContext, tt: ru.TypeTag[C]): Future[ChannelRef[C]] = {
     import Channels._
     ref ? CheckType(tt) map {

akka-channels/src/main/scala/akka/channels/macros/CreateChild.scala

@@ -22,20 +22,35 @@ object CreateChild {
 
     import c.universe._
 
-    if (weakTypeOf[ParentChannels] =:= weakTypeOf[Nothing]) {
+    verify(c)(weakTypeOf[ParentChannels], weakTypeOf[ChildChannels], weakTypeOf[MyChannels])
-      c.abort(c.enclosingPosition, "Parent argument must not be Nothing")
-    }
-    if (weakTypeOf[ChildChannels] =:= weakTypeOf[Nothing]) {
-      c.abort(c.enclosingPosition, "channel list must not be Nothing")
-    }
 
-    val missing = missingChannels(c.universe)(weakTypeOf[MyChannels], inputChannels(c.universe)(weakTypeOf[ParentChannels]))
+    implicit val t = c.TypeTag[ChildChannels](c.weakTypeOf[ChildChannels])
-    if (missing.isEmpty) {
+    reify(new ChannelRef[ChildChannels](c.prefix.splice.context.actorOf(Props(factory.splice))))
-      implicit val t = c.TypeTag[ChildChannels](c.weakTypeOf[ChildChannels])
+  }
-      reify(new ChannelRef[ChildChannels](c.prefix.splice.context.actorOf(Props(factory.splice))))
+
-    } else {
+  def implName[MyChannels <: ChannelList: c.WeakTypeTag, ParentChannels <: ChannelList: c.WeakTypeTag, ChildChannels <: ChannelList: c.WeakTypeTag](
-      c.abort(c.enclosingPosition, s"This actor cannot support a child requiring channels ${missing mkString ", "}")
+    c: Context {
-    }
+      type PrefixType = Actor with Channels[_, MyChannels]
+    })(factory: c.Expr[Actor with Channels[ParentChannels, ChildChannels]], name: c.Expr[String]): c.Expr[ChannelRef[ChildChannels]] = {
+
+    import c.universe._
+
+    verify(c)(weakTypeOf[ParentChannels], weakTypeOf[ChildChannels], weakTypeOf[MyChannels])
+
+    implicit val t = c.TypeTag[ChildChannels](c.weakTypeOf[ChildChannels])
+    reify(new ChannelRef[ChildChannels](c.prefix.splice.context.actorOf(Props(factory.splice), name.splice)))
+  }
+
+  def verify(c: Context)(parent: c.Type, child: c.Type, mine: c.Type): Unit = {
+    import c.universe._
+
+    val nothing = weakTypeOf[Nothing]
+    if (parent =:= nothing) abort(c, "Parent argument must not be Nothing")
+    if (child =:= nothing) abort(c, "channel list must not be Nothing")
+
+    val missing = missingChannels(c.universe)(mine, inputChannels(c.universe)(parent))
+    if (missing.nonEmpty)
+      abort(c, s"This actor cannot support a child requiring channels ${missing mkString ", "}")
   }
 
 }

akka-docs/rst/scala/code/docs/channels/ChannelDocSpec.scala

@@ -176,7 +176,7 @@ class ChannelDocSpec extends AkkaSpec {
 
     // type given just for demonstration purposes
     val latch: ChannelRef[(Request, Reply) :+: (String, Int) :+: TNil] =
-      ChannelExt(system).actorOf(new Latch(target))
+      ChannelExt(system).actorOf(new Latch(target), "latch")
 
     "hello" -!-> latch
     //#processing
@@ -203,7 +203,7 @@ class ChannelDocSpec extends AkkaSpec {
     // then it is used somewhat like this:
     // 
 
-    val parent = ChannelExt(system).actorOf(new Parent)
+    val parent = ChannelExt(system).actorOf(new Parent, "parent")
     parent <-!- GetChild
     val child = expectMsgType[ChildRef].child // this assumes TestKit context
 

akka-docs/rst/scala/typed-channels.rst

@@ -40,7 +40,7 @@ an error, since the companion object ``Command`` is not an instance of type
 
 While this example looks pretty simple, the implications are profound. In order
 to be useful, the system must be as reliable as you would expect a type system
-to be. This means that unless you step outside of the it (i.e. doing the
+to be. This means that unless you step outside of it (i.e. doing the
 equivalent of ``.asInstanceOf[_]``) you shall be protected, failures shall be
 recognized and flagged. There are a number of challenges included in this
 requirement, which are discussed in the following sections. If you are reading