Moving in isEmpty and count into AbstractNodeQueue

akka-actor/src/main/java/akka/dispatch/AbstractNodeQueue.java

@@ -31,6 +31,17 @@ public abstract class AbstractNodeQueue<T> extends AtomicReference<AbstractNodeQ
         getAndSet(n).setNext(n);
     }
 
+    public final boolean isEmpty() {
+        return peek() == null;
+    }
+
+    public final int count() {
+        int count = 0;
+        for(Node<T> n = peek();n != null; n = n.next())
+          ++count;
+        return count;
+    }
+
     @SuppressWarnings("unchecked")
     public final T poll() {
         final Node<T> next = peek();

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

@@ -353,12 +353,9 @@ class NodeMessageQueue extends AbstractNodeQueue[Envelope] with MessageQueue {
 
   final def dequeue(): Envelope = poll()
 
-  final def numberOfMessages: Int = {
-    @tailrec def count(node: AbstractNodeQueue.Node[Envelope], c: Int): Int = if (node eq null) c else count(node.next(), c + 1)
-    count(peek(), 0)
-  }
+  final def numberOfMessages: Int = count()
 
-  final def hasMessages: Boolean = peek() ne null
+  final def hasMessages: Boolean = !isEmpty()
 
   @tailrec final def cleanUp(owner: ActorRef, deadLetters: MessageQueue): Unit = {
     val envelope = dequeue()
@@ -535,11 +532,11 @@ case class UnboundedMailbox() extends MailboxType {
 }
 
 /**
- * MPSCUnboundedMailbox is a high-performance unbounded MailboxType,
+ * SingleConsumerOnlyUnboundedMailbox is a high-performance, multiple producer—single consumer, unbounded MailboxType,
  * the only drawback is that you can't have multiple consumers,
  * which rules out using it with BalancingDispatcher for instance.
  */
-case class MPSCUnboundedMailbox() extends MailboxType {
+case class SingleConsumerOnlyUnboundedMailbox() extends MailboxType {
 
   def this(settings: ActorSystem.Settings, config: Config) = this()
 

akka-actor/src/main/scala/akka/util/SerializedSuspendableExecutionContext.scala

@@ -76,12 +76,11 @@ private[akka] final class SerializedSuspendableExecutionContext(throughput: Int)
   override final def execute(task: Runnable): Unit = try add(task) finally attach()
   override final def reportFailure(t: Throwable): Unit = context reportFailure t
 
-  final def size(): Int = {
-    @tailrec def count(node: AbstractNodeQueue.Node[Runnable], c: Int): Int = if (node eq null) c else count(node.next(), c + 1)
-    count(peek(), 0)
-  }
-
-  final def isEmpty(): Boolean = peek() eq null
+  /**
+   * O(N)
+   * @return the number of Runnable's currently enqueued
+   */
+  final def size(): Int = count()
 
   override final def toString: String = (state.get: @switch) match {
     case 0 ⇒ "Off"