clean up Channel API (fixes #1070)

- remove feature query methods
- encode information in marker traits
- remove safe_!
- rename tellSafe to tryTell (harmonize with ActorRef.reply)

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

@@ -7,14 +7,33 @@ package akka.actor
 import org.scalatest.WordSpec
 import org.scalatest.matchers.MustMatchers
 import akka.dispatch._
+import akka.testkit.TestActorRef
 
 class ChannelSpec extends WordSpec with MustMatchers {
+
   "A Channel" must {
+
     "be contravariant" in {
       val ap = new ActorPromise(1000)
       val p: Promise[Any] = ap
       val c: Channel[Any] = ap
       val cs: Channel[String] = c
     }
+
+    "find implicit sender actors" in {
+      var s: (String, UntypedChannel) = null
+      val ch = new Channel[String] {
+        def !(msg: String)(implicit sender: UntypedChannel) = { s = (msg, sender) }
+      }
+      val a = TestActorRef(new Actor {
+        def receive = {
+          case str: String ⇒ ch ! str
+        }
+      }).start()
+      a ! "hallo"
+      s must be(("hallo", a))
+    }
+
   }
+
 }

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

@@ -71,7 +71,7 @@ private[akka] object ActorRefInternals {
  *
  * @author <a href="http://jonasboner.com">Jonas Bon&#233;r</a>
  */
-abstract class ActorRef extends ActorRefShared with ForwardableChannel with java.lang.Comparable[ActorRef] with Serializable {
+abstract class ActorRef extends ActorRefShared with ForwardableChannel with ReplyChannel[Any] with java.lang.Comparable[ActorRef] with Serializable {
   scalaRef: ScalaActorRef ⇒
   // Only mutable for RemoteServer in order to maintain identity across nodes
   @volatile
@@ -303,7 +303,7 @@ abstract class ActorRef extends ActorRefShared with ForwardableChannel with java
    *
    * If you would rather have an exception, check the <code>reply(..)</code> version.
    */
-  def tryReply(message: Any): Boolean = channel.safe_!(message)(this)
+  def tryReply(message: Any): Boolean = channel.tryTell(message, this)
 
   /**
    * Sets the dispatcher for this actor. Needs to be invoked before the actor is started.
@@ -386,20 +386,6 @@ abstract class ActorRef extends ActorRefShared with ForwardableChannel with java
     else NullChannel
   }
 
-  /*
-   * Implementation of ForwardableChannel
-   */
-
-  def sendException(ex: Throwable) {}
-
-  def isUsableOnlyOnce = false
-
-  def isUsable = true
-
-  def isReplyable = true
-
-  def canSendException = false
-
   /**
    * Java API. <p/>
    * Abstraction for unification of sender and senderFuture for later reply
@@ -1129,7 +1115,7 @@ trait ActorRefShared {
  * There are implicit conversions in ../actor/Implicits.scala
  * from ActorRef -> ScalaActorRef and back
  */
-trait ScalaActorRef extends ActorRefShared with ForwardableChannel {
+trait ScalaActorRef extends ActorRefShared with ForwardableChannel with ReplyChannel[Any] {
   ref: ActorRef ⇒
 
   /**

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

@@ -18,45 +18,17 @@ trait Channel[-T] {
    * Scala API. <p/>
    * Sends the specified message to the channel.
    */
-  def !(msg: T)(implicit channel: UntypedChannel = NullChannel): Unit
+  def !(msg: T)(implicit channel: UntypedChannel): Unit
 
   /**
    * Try to send an exception. Not all channel types support this, one notable
    * positive example is Future. Failure to send is silent.
+   *
+   * @return whether sending was successful
    */
-  def sendException(ex: Throwable): Unit
+  def sendException(ex: Throwable): Boolean = false
 
   /**
-   * Scala API.<p/>
-   * Try to send message to the channel, return whether successful.
-   */
-  def safe_!(msg: T)(implicit channel: UntypedChannel = NullChannel): Boolean
-
-  /**
-   * Indicates whether this channel may be used only once, e.g. a Future.
-   */
-  def isUsableOnlyOnce: Boolean
-
-  /**
-   * Indicates whether this channel may still be used (only useful if
-   * isUsableOnlyOnce returns true).
-   */
-  def isUsable: Boolean
-
-  /**
-   * Indicates whether this channel carries reply information, e.g. an
-   * ActorRef.
-   */
-  def isReplyable: Boolean
-
-  /**
-   * Indicates whether this channel is capable of sending exceptions to its
-   * recipient.
-   */
-  def canSendException: Boolean
-
-  /**
-   * Java API.<p/>
    * Sends the specified message to the channel, i.e. fire-and-forget semantics.<p/>
    * <pre>
    * actor.tell(message);
@@ -76,13 +48,12 @@ trait Channel[-T] {
   def tell(msg: T, sender: UntypedChannel): Unit = this.!(msg)(sender)
 
   /**
-   * Java API.<p/>
    * Try to send the specified message to the channel, i.e. fire-and-forget semantics.<p/>
    * <pre>
-   * actor.tell(message);
+   * channel.tell(message);
    * </pre>
    */
-  def tellSafe(msg: T): Boolean = this.safe_!(msg)
+  def tryTell(msg: T): Boolean = this.tryTell(msg, NullChannel)
 
   /**
    * Java API. <p/>
@@ -93,27 +64,33 @@ trait Channel[-T] {
    * actor.tell(message, context);
    * </pre>
    */
-  def tellSafe(msg: T, sender: UntypedChannel): Boolean = this.safe_!(msg)(sender)
+  def tryTell(msg: T, sender: UntypedChannel): Boolean = {
+    try {
+      this.!(msg)(sender)
+      true
+    } catch {
+      case _: Exception ⇒ false
+    }
+  }
 
 }
 
 /**
- * This trait represents a channel that a priori does have sending capability,
+ * This trait marks a channel that a priori does have sending capability,
  * i.e. ! is not guaranteed to fail (e.g. NullChannel would be a
  * counter-example).
  */
-trait AvailableChannel[-T] { self: Channel[T] ⇒
-  def safe_!(msg: T)(implicit channel: UntypedChannel = NullChannel): Boolean = {
-    if (isUsable) {
-      try {
-        this ! msg
-        true
-      } catch {
-        case _ ⇒ false
-      }
-    } else false
-  }
-}
+trait AvailableChannel[-T] extends Channel[T]
+
+/**
+ * This trait marks a channel which is capable of sending exceptions.
+ */
+trait ExceptionChannel[-T] extends AvailableChannel[T]
+
+/**
+ * This trait marks a channel which carries reply information when tell()ing.
+ */
+trait ReplyChannel[-T] extends AvailableChannel[T]
 
 /**
  * All channels used in conjunction with MessageInvocation are untyped by
@@ -129,14 +106,13 @@ object UntypedChannel {
     }
 
   implicit final val default: UntypedChannel = NullChannel
-
 }
 
 /**
  * Default channel when none available.
  */
 case object NullChannel extends UntypedChannel {
-  def !(msg: Any)(implicit channel: UntypedChannel = NullChannel) {
+  def !(msg: Any)(implicit channel: UntypedChannel) {
     throw new IllegalActorStateException("""
    No sender in scope, can't reply.
    You have probably:
@@ -144,12 +120,7 @@ case object NullChannel extends UntypedChannel {
       2. Invoked a method on an TypedActor from an instance NOT an TypedActor.
    You may want to have a look at safe_! for a variant returning a Boolean""")
   }
-  def safe_!(msg: Any)(implicit channel: UntypedChannel = NullChannel): Boolean = false
-  def sendException(ex: Throwable) {}
-  def isUsableOnlyOnce = false
-  def isUsable = false
-  def isReplyable = false
-  def canSendException = false
+  def tryTell(msg: Any)(implicit channel: UntypedChannel, dummy: Int = 0): Boolean = false
 }
 
 /**

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

@@ -6,7 +6,7 @@ package akka.dispatch
 
 import akka.AkkaException
 import akka.event.EventHandler
-import akka.actor.{ Actor, Channel, ForwardableChannel, NullChannel, UntypedChannel, ActorRef, Scheduler, Timeout }
+import akka.actor.{ Actor, Channel, ForwardableChannel, NullChannel, UntypedChannel, ActorRef, Scheduler, Timeout, ExceptionChannel }
 import akka.util.{ Duration, BoxedType }
 import akka.japi.{ Procedure, Function ⇒ JFunc }
 
@@ -1012,21 +1012,17 @@ class DefaultPromise[T](val timeout: Timeout) extends Promise[T] {
   private def timeLeft(): Long = timeoutInNanos - (currentTimeInNanos - _startTimeInNanos)
 }
 
-class ActorPromise(timeout: Timeout) extends DefaultPromise[Any](timeout) with ForwardableChannel {
+class ActorPromise(timeout: Timeout) extends DefaultPromise[Any](timeout) with ForwardableChannel with ExceptionChannel[Any] {
 
-  def !(message: Any)(implicit channel: UntypedChannel = NullChannel) = completeWithResult(message)
+  def !(message: Any)(implicit channel: UntypedChannel) = completeWithResult(message)
 
-  def sendException(ex: Throwable) = completeWithException(ex)
+  override def sendException(ex: Throwable) = {
+    completeWithException(ex)
+    value == Some(Left(ex))
+  }
 
   def channel: UntypedChannel = this
 
-  def isUsableOnlyOnce = true
-  def isUsable = !isCompleted
-  def isReplyable = false
-  def canSendException = true
-
-  @deprecated("ActorPromise merged with Channel[Any], just use 'this'", "1.2")
-  def future = this
 }
 
 object ActorPromise {
@@ -1034,7 +1030,10 @@ object ActorPromise {
     new ActorPromise(f.timeout) {
       completeWith(f)
       override def !(message: Any)(implicit channel: UntypedChannel) = f completeWithResult message
-      override def sendException(ex: Throwable) = f completeWithException ex
+      override def sendException(ex: Throwable) = {
+        f completeWithException ex
+        f.value == Some(Left(ex))
+      }
     }
 }
 

akka-docs/java/untyped-actors.rst

@@ -240,7 +240,7 @@ which you do by Channel.tell(msg)
       String msg = (String)message;
       if (msg.equals("Hello")) {
         // Reply to original sender of message using the channel
-        getContext().channel().tellSafe(msg + " from " + getContext().getUuid());
+        getContext().channel().tryTell(msg + " from " + getContext().getUuid());
       }
     }
   }