Added load balancer which prefers actors with small mailboxes (discussed on mailing list a while ago).

akka-patterns/src/main/scala/Patterns.scala

@@ -73,4 +73,15 @@ class CyclicIterator[T](items: List[T]) extends InfiniteIterator[T] {
     current = nc.tail
     nc.head
   }
-}
+}
+
+class SmallestMailboxFirstIterator(items : List[Actor]) extends InfiniteIterator[Actor] {
+  def hasNext = items != Nil
+
+  def next = {
+    def actorWithSmallestMailbox(a1: Actor, a2: Actor) = {
+      if (a1.mailboxSize < a2.mailboxSize) a1 else a2
+    }
+    items.reduceLeft((actor1, actor2) => actorWithSmallestMailbox(actor1,actor2))
+  }
+}