Minor cleanup

platform/arcus-lib/src/main/java/com/iris/platform/cluster/zookeeper/ZookeeperClusterServiceDao.java

@@ -82,7 +82,7 @@ public ClusterServiceRecord register() throws ClusterIdUnavailableException {
                         .collect(Collectors.toList());
         try (Timer.Context timer = ZookeeperClusterServiceDao.ClusterServiceMetrics.registerTimer.time()) {
             Instant heartbeat = clock.instant();
-            // try to grab an empty first
+            // grab an empty cluster id, or wait
             for (int i = 0; i < members; i++) {
                 if (others.contains(i)) {
                     continue;
@@ -96,8 +96,6 @@ public ClusterServiceRecord register() throws ClusterIdUnavailableException {
                     ZookeeperClusterServiceDao.ClusterServiceMetrics.clusterRegistrationMissCounter.inc();
                 }
             }
-            // try to grab an existing one then
-            // TODO: is this actually needed?
 
             ZookeeperClusterServiceDao.ClusterServiceMetrics.clusterRegistrationFailedCounter.inc();
             throw new ClusterIdUnavailableException("No cluster ids for service [" + service + "] were available");
@@ -135,6 +133,7 @@ private ClusterServiceRecord tryInsert(int memberId, Instant heartbeat) {
 
     @Override
     public ClusterServiceRecord heartbeat(ClusterServiceRecord service) throws ClusterServiceDaoException {
+        // Not required for this implementation - ZooKeeper will automatically expire ephemeral nodes.
         return null;
     }
 
@@ -183,7 +182,6 @@ public void process(WatchedEvent event) {
 
     private static class ClusterServiceMetrics {
         static final Timer registerTimer = DaoMetrics.upsertTimer(ClusterServiceDao.class, "register");
-        static final Timer heartbeatTimer = DaoMetrics.updateTimer(ClusterServiceDao.class, "heartbeat");
         static final Timer deregisterTimer = DaoMetrics.deleteTimer(ClusterServiceDao.class, "deregister");
         static final Timer listByServiceTimer = DaoMetrics.readTimer(ClusterServiceDao.class, "listMembersByService");
         static final Counter clusterIdRegisteredCounter = DaoMetrics.counter(ClusterServiceDao.class, "clusterid.registered");

platform/arcus-lib/src/main/java/com/iris/platform/cluster/zookeeper/ZookeeperMonitor.java

@@ -34,12 +34,12 @@ public ZookeeperMonitor(ZooKeeper zk) {
 
     @Override
     public void process(WatchedEvent event) {
-        String path = event.getPath();
         if (event.getType() == Event.EventType.None) {
             switch (event.getState()) {
                 case SyncConnected:
                     break;
                 case Expired:
+                    // TODO: move this elsewhere?
                     logger.error("SHUTTING DOWN -- zookeeper session has been marked as expired");
                     System.err.println("SHUTTING DOWN -- zookeeper session has been marked as expired");
                     System.exit(-1);