ONOS-1326: Added support for observing when node liveness status was last updated. Useful for detecting/debugging stability issues.

Change-Id: I8ffebcf3a09a51c6e3e7526986a0f05530ed757f
diff --git a/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java b/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java
index 213d0f4..90fbd60 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java
@@ -38,6 +38,7 @@
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Service;
+import org.joda.time.DateTime;
 import org.onlab.netty.Endpoint;
 import org.onlab.netty.Message;
 import org.onlab.netty.MessageHandler;
@@ -99,6 +100,7 @@
     private Set<ControllerNode> seedNodes;
     private final Map<NodeId, ControllerNode> allNodes = Maps.newConcurrentMap();
     private final Map<NodeId, State> nodeStates = Maps.newConcurrentMap();
+    private final Map<NodeId, DateTime> nodeStateLastUpdatedTimes = Maps.newConcurrentMap();
     private NettyMessagingService messagingService = new NettyMessagingService();
     private ScheduledExecutorService heartBeatSender = Executors.newSingleThreadScheduledExecutor(
             groupedThreads("onos/cluster/membership", "heartbeat-sender"));
@@ -131,7 +133,7 @@
 
         seedNodes.forEach(node -> {
             allNodes.put(node.id(), node);
-            nodeStates.put(node.id(), State.INACTIVE);
+            updateState(node.id(), State.INACTIVE);
         });
 
         establishSelfIdentity();
@@ -216,7 +218,7 @@
         checkArgument(tcpPort > 5000, "Tcp port must be greater than 5000");
         ControllerNode node = new DefaultControllerNode(nodeId, ip, tcpPort);
         allNodes.put(node.id(), node);
-        nodeStates.put(nodeId, State.INACTIVE);
+        updateState(nodeId, State.INACTIVE);
         delegate.notify(new ClusterEvent(ClusterEvent.Type.INSTANCE_ADDED, node));
         return node;
     }
@@ -231,12 +233,17 @@
         }
     }
 
+    private void updateState(NodeId nodeId, State newState) {
+        nodeStates.put(nodeId, newState);
+        nodeStateLastUpdatedTimes.put(nodeId, DateTime.now());
+    }
+
     private void establishSelfIdentity() {
         try {
             IpAddress ip = findLocalIp();
             localNode = new DefaultControllerNode(new NodeId(ip.toString()), ip);
             allNodes.put(localNode.id(), localNode);
-            nodeStates.put(localNode.id(), State.ACTIVE);
+            updateState(localNode.id(), State.ACTIVE);
             log.info("Local Node: {}", localNode);
         } catch (SocketException e) {
             throw new IllegalStateException("Cannot determine local IP", e);
@@ -256,12 +263,12 @@
                 double phi = failureDetector.phi(node.id());
                 if (phi >= PHI_FAILURE_THRESHOLD) {
                     if (currentState == State.ACTIVE) {
-                        nodeStates.put(node.id(), State.INACTIVE);
+                        updateState(node.id(), State.INACTIVE);
                         notifyStateChange(node.id(), State.ACTIVE, State.INACTIVE);
                     }
                 } else {
                     if (currentState == State.INACTIVE) {
-                        nodeStates.put(node.id(), State.ACTIVE);
+                        updateState(node.id(), State.ACTIVE);
                         notifyStateChange(node.id(), State.INACTIVE, State.ACTIVE);
                     }
                 }
@@ -334,4 +341,8 @@
         }
     }
 
-}
+    @Override
+    public DateTime getLastUpdated(NodeId nodeId) {
+        return nodeStateLastUpdatedTimes.get(nodeId);
+    }
+}
\ No newline at end of file
diff --git a/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/HazelcastClusterStore.java b/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/HazelcastClusterStore.java
index d32f7a8..55d877d 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/HazelcastClusterStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/HazelcastClusterStore.java
@@ -18,6 +18,7 @@
 import com.google.common.base.Optional;
 import com.google.common.cache.LoadingCache;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Maps;
 import com.hazelcast.core.IMap;
 import com.hazelcast.core.Member;
 import com.hazelcast.core.MemberAttributeEvent;
@@ -28,6 +29,7 @@
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Service;
+import org.joda.time.DateTime;
 import org.onosproject.cluster.ClusterEvent;
 import org.onosproject.cluster.ClusterStore;
 import org.onosproject.cluster.ClusterStoreDelegate;
@@ -63,6 +65,7 @@
     private String listenerId;
     private final MembershipListener listener = new InternalMembershipListener();
     private final Map<NodeId, State> states = new ConcurrentHashMap<>();
+    private final Map<NodeId, DateTime> lastUpdatedTimes = Maps.newConcurrentMap();
 
     private String nodesListenerId;
 
@@ -123,6 +126,11 @@
     }
 
     @Override
+    public DateTime getLastUpdated(NodeId nodeId) {
+        return lastUpdatedTimes.get(nodeId);
+    }
+
+    @Override
     public ControllerNode addNode(NodeId nodeId, IpAddress ip, int tcpPort) {
         return addNode(new DefaultControllerNode(nodeId, ip, tcpPort));
     }
@@ -139,7 +147,7 @@
     private synchronized ControllerNode addNode(DefaultControllerNode node) {
         rawNodes.put(serialize(node.id()), serialize(node));
         nodes.put(node.id(), Optional.of(node));
-        states.put(node.id(), State.ACTIVE);
+        updateState(node.id(), State.ACTIVE);
         return node;
     }
 
@@ -153,6 +161,11 @@
         return IpAddress.valueOf(member.getSocketAddress().getAddress());
     }
 
+    private void updateState(NodeId nodeId, State newState) {
+        updateState(nodeId, newState);
+        lastUpdatedTimes.put(nodeId, DateTime.now());
+    }
+
     // Interceptor for membership events.
     private class InternalMembershipListener implements MembershipListener {
         @Override
@@ -166,7 +179,7 @@
         public void memberRemoved(MembershipEvent membershipEvent) {
             log.info("Member {} removed", membershipEvent.getMember());
             NodeId nodeId = new NodeId(memberAddress(membershipEvent.getMember()).toString());
-            states.put(nodeId, State.INACTIVE);
+            updateState(nodeId, State.INACTIVE);
             notifyDelegate(new ClusterEvent(INSTANCE_DEACTIVATED, getNode(nodeId)));
         }
 
@@ -178,4 +191,4 @@
                      memberAttributeEvent.getValue());
         }
     }
-}
+}
\ No newline at end of file