Merge pull request #21813 from akka/wip-21518-patriknw

minor cleanup of cluster.subscribe usage

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ShardCoordinator.scala

@@ -21,6 +21,7 @@ import akka.cluster.ddata.Replicator._
 import akka.dispatch.ExecutionContexts
 import akka.pattern.{ AskTimeoutException, pipe }
 import akka.persistence._
+import akka.cluster.ClusterEvent
 
 /**
  * @see [[ClusterSharding$ ClusterSharding extension]]
@@ -840,7 +841,7 @@ class DDataShardCoordinator(typeName: String, settings: ClusterShardingSettings,
   val CoordinatorStateKey = LWWRegisterKey[State](s"${typeName}CoordinatorState")
   val initEmptyState = State.empty.withRememberEntities(settings.rememberEntities)
 
-  node.subscribe(self, ClusterShuttingDown.getClass)
+  node.subscribe(self, ClusterEvent.InitialStateAsEvents, ClusterShuttingDown.getClass)
 
   // get state from ddata replicator, repeat until GetSuccess
   getState()

akka-cluster-tools/src/main/scala/akka/cluster/singleton/ClusterSingletonManager.scala

@@ -24,6 +24,7 @@ import akka.cluster.MemberStatus
 import akka.AkkaException
 import akka.actor.NoSerializationVerificationNeeded
 import akka.cluster.UniqueAddress
+import akka.cluster.ClusterEvent
 
 object ClusterSingletonManagerSettings {
 
@@ -435,7 +436,7 @@ class ClusterSingletonManager(
     require(!cluster.isTerminated, "Cluster node must not be terminated")
 
     // subscribe to cluster changes, re-subscribe when restart
-    cluster.subscribe(self, classOf[MemberExited], classOf[MemberRemoved])
+    cluster.subscribe(self, ClusterEvent.InitialStateAsEvents, classOf[MemberExited], classOf[MemberRemoved])
 
     setTimer(CleanupTimer, Cleanup, 1.minute, repeat = true)
 
@@ -715,7 +716,6 @@ class ClusterSingletonManager(
   }
 
   whenUnhandled {
-    case Event(_: CurrentClusterState, _) ⇒ stay
     case Event(MemberExited(m), _) ⇒
       if (m.uniqueAddress == cluster.selfUniqueAddress) {
         selfExited = true