Additions for Java API of cluster, see #2502

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

@@ -32,7 +32,38 @@ object ClusterEvent {
     unreachable: Set[Member] = Set.empty,
     convergence: Boolean = false,
     seenBy: Set[Address] = Set.empty,
-    leader: Option[Address] = None) extends ClusterDomainEvent
+    leader: Option[Address] = None) extends ClusterDomainEvent {
+
+    /**
+     * Java API
+     */
+    def getMembers: java.lang.Iterable[Member] = {
+      import scala.collection.JavaConverters._
+      members.asJava
+    }
+
+    /**
+     * Java API
+     */
+    def getUnreachable: java.util.Set[Member] = {
+      import scala.collection.JavaConverters._
+      unreachable.asJava
+    }
+
+    /**
+     * Java API
+     */
+    def getSeenBy: java.util.Set[Address] = {
+      import scala.collection.JavaConverters._
+      seenBy.asJava
+    }
+
+    /**
+     * Java API
+     * @return address of current leader, or null if none
+     */
+    def getLeader: Address = leader orNull
+  }
 
   /**
    * Marker interface for member related events.
@@ -88,11 +119,6 @@ object ClusterEvent {
     if (member.status != Removed) throw new IllegalArgumentException("Expected Removed status, got: " + member)
   }
 
-  /**
-   * Current snapshot of cluster member metrics. Published to subscribers.
-   */
-  case class ClusterMetricsChanged(nodes: Set[NodeMetrics]) extends ClusterDomainEvent
-
   /**
    * Cluster convergence state changed.
    */
@@ -101,7 +127,20 @@ object ClusterEvent {
   /**
    * Leader of the cluster members changed. Only published after convergence.
    */
-  case class LeaderChanged(leader: Option[Address]) extends ClusterDomainEvent
+  case class LeaderChanged(leader: Option[Address]) extends ClusterDomainEvent {
+    /**
+     * Java API
+     * @return address of current leader, or null if none
+     */
+    def getLeader: Address = leader orNull
+  }
+
+  /**
+   * INTERNAL API
+   *
+   * Current snapshot of cluster member metrics. Published to subscribers.
+   */
+  case class ClusterMetricsChanged(nodes: Set[NodeMetrics]) extends ClusterDomainEvent
 
   /**
    * INTERNAL API

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

@@ -22,6 +22,8 @@ import java.lang.reflect.Method
 import java.lang.System.{ currentTimeMillis ⇒ newTimestamp }
 
 /**
+ * INTERNAL API.
+ *
  * This strategy is primarily for load-balancing of nodes. It controls metrics sampling
  * at a regular frequency, prepares highly variable data for further analysis by other entities,
  * and publishes the latest cluster metrics data around the node ring to assist in determining
@@ -32,8 +34,6 @@ import java.lang.System.{ currentTimeMillis ⇒ newTimestamp }
  * Calculation of statistical data for each monitored process is delegated to the
  * [[akka.cluster.DataStream]] for exponential smoothing, with additional decay factor.
  *
- * INTERNAL API.
- *
  * @author Helena Edelson
  */
 private[cluster] class ClusterMetricsCollector(publisher: ActorRef) extends Actor with ActorLogging {
@@ -119,8 +119,6 @@ private[cluster] class ClusterMetricsCollector(publisher: ActorRef) extends Acto
    * Samples the latest metrics for the node, updates metrics statistics in
    * [[akka.cluster.MetricsGossip]], and publishes the change to the event bus.
    *
-   * INTERNAL API
-   *
    * @see [[akka.cluster.ClusterMetricsCollector.collect( )]]
    */
   def collect(): Unit = {
@@ -220,8 +218,8 @@ private[cluster] case class MetricsGossip(rateOfDecay: Int, nodes: Set[NodeMetri
 }
 
 /**
- * Envelope adding a sender address to the gossip.
  * INTERNAL API
+ * Envelope adding a sender address to the gossip.
  */
 private[cluster] case class MetricsGossipEnvelope(from: Address, gossip: MetricsGossip) extends ClusterMessage
 
@@ -277,6 +275,8 @@ private[cluster] case class DataStream(decay: Int, ewma: ScalaNumber, startTime:
 }
 
 /**
+ * INTERNAL API
+ *
  * Companion object of DataStream class.
  *
  * @author Helena Edelson
@@ -348,6 +348,8 @@ private[cluster] case class Metric(name: String, value: Option[ScalaNumber], ave
 }
 
 /**
+ * INTERNAL API
+ *
  * Companion object of Metric class.
  *
  * @author Helena Edelson
@@ -372,6 +374,8 @@ private[cluster] object Metric extends MetricNumericConverter {
 }
 
 /**
+ * INTERNAL API
+ *
  * The snapshot of current sampled health metrics for any monitored process.
  * Collected and gossipped at regular intervals for dynamic cluster management strategies.
  *
@@ -409,11 +413,11 @@ private[cluster] case class NodeMetrics(address: Address, timestamp: Long, metri
 }
 
 /**
+ * INTERNAL API
+ *
  * Encapsulates evaluation of validity of metric values, conversion of an actual metric value to
  * a [[akka.cluster.Metric]] for consumption by subscribed cluster entities.
  *
- * INTERNAL API
- *
  * @author Helena Edelson
  */
 private[cluster] trait MetricNumericConverter {
@@ -439,13 +443,13 @@ private[cluster] trait MetricNumericConverter {
 }
 
 /**
+ * INTERNAL API
+ *
  * Loads JVM metrics through JMX monitoring beans. If Hyperic SIGAR is on the classpath, this
  * loads wider and more accurate range of metrics in combination with SIGAR's native OS library.
  *
  * FIXME switch to Scala reflection
  *
- * INTERNAL API
- *
  * @param sigar the optional org.hyperic.Sigar instance
  *
  * @param address The [[akka.actor.Address]] of the node being sampled
@@ -562,6 +566,8 @@ private[cluster] class MetricsCollector private (private val sigar: Option[AnyRe
 }
 
 /**
+ * INTERNAL API
+ *
  * Companion object of MetricsCollector class.
  *
  * @author Helena Edelson

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

@@ -87,7 +87,7 @@ object Member {
  *
  * Can be one of: Joining, Up, Leaving, Exiting and Down.
  */
-sealed trait MemberStatus extends ClusterMessage {
+abstract class MemberStatus extends ClusterMessage {
 
   /**
    * Using the same notion for 'unavailable' as 'non-convergence': DOWN
@@ -102,4 +102,34 @@ object MemberStatus {
   case object Exiting extends MemberStatus
   case object Down extends MemberStatus
   case object Removed extends MemberStatus
+
+  /**
+   * JAVA API
+   */
+  def joining: Object = Joining
+
+  /**
+   * JAVA API
+   */
+  def up: Object = Up
+
+  /**
+   * JAVA API
+   */
+  def leaving: Object = Leaving
+
+  /**
+   * JAVA API
+   */
+  def exiting: Object = Exiting
+
+  /**
+   * JAVA API
+   */
+  def down: Object = Down
+
+  /**
+   * JAVA API
+   */
+  def removed: Object = Removed
 }