Incorporate feedback from review, see #2214

akka-cluster/src/main/scala/akka/cluster/Cluster.scala

@@ -14,18 +14,14 @@ import akka.pattern.ask
 import akka.util._
 import akka.util.duration._
 import akka.ConfigurationException
-
 import java.util.concurrent.atomic.{ AtomicReference, AtomicBoolean }
 import java.util.concurrent.TimeUnit._
 import java.util.concurrent.TimeoutException
 import akka.jsr166y.ThreadLocalRandom
-
 import java.lang.management.ManagementFactory
 import javax.management._
-
 import scala.collection.immutable.{ Map, SortedSet }
 import scala.annotation.tailrec
-
 import com.google.protobuf.ByteString
 
 /**
@@ -44,6 +40,8 @@ trait MetaDataChangeListener {
 
 /**
  * Base trait for all cluster messages. All ClusterMessage's are serializable.
+ *
+ * FIXME Protobuf all ClusterMessages
  */
 sealed trait ClusterMessage extends Serializable
 
@@ -82,6 +80,7 @@ object ClusterAction {
 
 /**
  * Represents the address and the current status of a cluster member node.
+ *
  */
 class Member(val address: Address, val status: MemberStatus) extends ClusterMessage {
   override def hashCode = address.##
@@ -175,6 +174,10 @@ case class GossipOverview(
       "])"
 }
 
+object Gossip {
+  val emptyMembers: SortedSet[Member] = SortedSet.empty
+}
+
 /**
  * Represents the state of the cluster; cluster ring membership, ring convergence, meta data - all versioned by a vector clock.
  */
@@ -219,7 +222,7 @@ case class Gossip(
 
     // 3. merge members by selecting the single Member with highest MemberStatus out of the Member groups
     val mergedMembers =
-      SortedSet.empty[Member] ++
+      Gossip.emptyMembers ++
         membersGroupedByAddress.values.foldLeft(Vector.empty[Member]) { (acc, members) ⇒
           acc :+ members.reduceLeft(Member.highestPriorityOf(_, _))
         }
@@ -244,7 +247,10 @@ case class Gossip(
       ")"
 }
 
-case class Heartbeat(from: Address)
+/**
+ * Sent at regular intervals for failure detection.
+ */
+case class Heartbeat(from: Address) extends ClusterMessage
 
 /**
  * Manages routing of the different cluster commands.
@@ -372,6 +378,8 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
   import clusterSettings._
 
   val selfAddress = remote.transport.address
+  private val selfHeartbeat = Heartbeat(selfAddress)
+
   val failureDetector = new AccrualFailureDetector(
     system, selfAddress, FailureDetectorThreshold, FailureDetectorMaxSampleSize)
 
@@ -402,7 +410,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
 
   private val state = {
     val member = Member(selfAddress, MemberStatus.Joining)
-    val versionedGossip = Gossip(members = SortedSet.empty[Member] + member) + vclockNode // add me as member and update my vector clock
+    val versionedGossip = Gossip(members = Gossip.emptyMembers + member) + vclockNode // add me as member and update my vector clock
     val seenVersionedGossip = versionedGossip seen selfAddress
     new AtomicReference[State](State(seenVersionedGossip))
   }
@@ -757,9 +765,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
   /**
    * INTERNAL API
    */
-  private[cluster] def receiveHeartbeat(from: Address): Unit = {
-    failureDetector heartbeat from
-  }
+  private[cluster] def receiveHeartbeat(from: Address): Unit = failureDetector heartbeat from
 
   /**
    * Joins the pre-configured contact point.
@@ -785,10 +791,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
     val newSelf = localSelf copy (status = newStatus)
 
     // change my state in 'gossip.members'
-    val newMembers = localMembers map { member ⇒
-      if (member.address == selfAddress) newSelf
-      else member
-    }
+    val newMembers = localMembers map { member ⇒ if (member.address == selfAddress) newSelf else member }
 
     val newGossip = localGossip copy (members = newMembers)
 
@@ -893,13 +896,11 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
 
     if (!isSingletonCluster(localState)) {
       val liveMembers = localState.latestGossip.members.toIndexedSeq
-      val unreachableMembers = localState.latestGossip.overview.unreachable
 
-      // FIXME use unreachable?
-      for (member ← (liveMembers ++ unreachableMembers); if member.address != selfAddress) {
+      for (member ← liveMembers; if member.address != selfAddress) {
         val connection = clusterGossipConnectionFor(member.address)
         log.debug("Cluster Node [{}] - Heartbeat to [{}]", selfAddress, connection)
-        connection ! Heartbeat(selfAddress)
+        connection ! selfHeartbeat
       }
     }
   }