Carry previous host subject in HostEvent

This is an enhanced version of gerrit 6085 that provides not only the old location
but also the entire old host subject.
The main purpose is allowing apps to be aware of the change of IP address as well

Change-Id: I448d73b0d1e705996259cb0ec777f959f485d9c2

@@ -98,7 +98,8 @@ public class DefaultHost extends AbstractElement implements Host {
             return Objects.equals(this.id, other.id) &&
                     Objects.equals(this.mac, other.mac) &&
                     Objects.equals(this.vlan, other.vlan) &&
-                    Objects.equals(this.location, other.location);
+                    Objects.equals(this.location, other.location) &&
+                    Objects.equals(this.ipAddresses(), other.ipAddresses());
         }
         return false;
     }

@@ -18,7 +18,6 @@ package org.onosproject.net.host;
 import org.joda.time.LocalDateTime;
 import org.onosproject.event.AbstractEvent;
 import org.onosproject.net.Host;
-import org.onosproject.net.HostLocation;
 
 import static com.google.common.base.MoreObjects.toStringHelper;
 
@@ -52,7 +51,7 @@ public class HostEvent extends AbstractEvent<HostEvent.Type, Host> {
         HOST_MOVED
     }
 
-    private HostLocation prevLocation;
+    private Host prevSubject;
 
     /**
      * Creates an event of a given type and for the specified host and the
@@ -77,25 +76,29 @@ public class HostEvent extends AbstractEvent<HostEvent.Type, Host> {
     }
 
     /**
-     * Creates an event with HOST_MOVED type along with the previous location
-     * of the host.
+     * Creates an event with previous subject.
      *
+     * The previous subject is ignored if the type is not moved or updated
+     *
+     * @param type host event type
      * @param host event host subject
-     * @param prevLocation previous location of the host
+     * @param prevSubject previous host subject
      */
-    public HostEvent(Host host, HostLocation prevLocation) {
-        super(Type.HOST_MOVED, host);
-        this.prevLocation = prevLocation;
+    public HostEvent(Type type, Host host, Host prevSubject) {
+        super(type, host);
+        if (type == Type.HOST_MOVED || type == Type.HOST_UPDATED) {
+            this.prevSubject = prevSubject;
+        }
     }
 
     /**
-     * Gets the previous location information in this host event.
+     * Gets the previous subject in this host event.
      *
-     * @return the previous location, or null if previous location is not
+     * @return the previous subject, or null if previous subject is not
      *         specified.
      */
-    public HostLocation prevLocation() {
-        return this.prevLocation;
+    public Host prevSubject() {
+        return this.prevSubject;
     }
 
     @Override
@@ -104,7 +107,7 @@ public class HostEvent extends AbstractEvent<HostEvent.Type, Host> {
                 .add("time", new LocalDateTime(time()))
                 .add("type", type())
                 .add("subject", subject())
-                .add("prevLocation", prevLocation())
+                .add("prevSubject", prevSubject())
                 .toString();
     }
 }

@@ -19,6 +19,7 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 import static org.onosproject.net.DefaultAnnotations.merge;
 import static org.onosproject.net.host.HostEvent.Type.HOST_ADDED;
+import static org.onosproject.net.host.HostEvent.Type.HOST_MOVED;
 import static org.onosproject.net.host.HostEvent.Type.HOST_REMOVED;
 import static org.onosproject.net.host.HostEvent.Type.HOST_UPDATED;
 import static org.onosproject.store.service.EventuallyConsistentMapEvent.Type.PUT;
@@ -88,7 +89,7 @@ public class ECHostStore
 
     private EventuallyConsistentMap<HostId, DefaultHost> hosts;
 
-    private final ConcurrentHashMap<HostId, HostLocation> locations =
+    private final ConcurrentHashMap<HostId, DefaultHost> prevHosts =
             new ConcurrentHashMap<>();
 
     private EventuallyConsistentMapListener<HostId, DefaultHost> hostLocationTracker =
@@ -114,7 +115,7 @@ public class ECHostStore
     public void deactivate() {
         hosts.removeListener(hostLocationTracker);
         hosts.destroy();
-        locations.clear();
+        prevHosts.clear();
 
         log.info("Stopped");
     }
@@ -253,16 +254,16 @@ public class ECHostStore
         public void event(EventuallyConsistentMapEvent<HostId, DefaultHost> event) {
             DefaultHost host = checkNotNull(event.value());
             if (event.type() == PUT) {
-                HostLocation prevLocation = locations.put(host.id(), host.location());
-                if (prevLocation == null) {
+                Host prevHost = prevHosts.put(host.id(), host);
+                if (prevHost == null) {
                     notifyDelegate(new HostEvent(HOST_ADDED, host));
-                } else if (!Objects.equals(prevLocation, host.location())) {
-                    notifyDelegate(new HostEvent(host, prevLocation));
-                } else {
-                    notifyDelegate(new HostEvent(HOST_UPDATED, host));
+                } else if (!Objects.equals(prevHost.location(), host.location())) {
+                    notifyDelegate(new HostEvent(HOST_MOVED, host, prevHost));
+                } else if (!Objects.equals(prevHost, host)) {
+                    notifyDelegate(new HostEvent(HOST_UPDATED, host, prevHost));
                 }
             } else if (event.type() == REMOVE) {
-                if (locations.remove(host.id()) != null) {
+                if (prevHosts.remove(host.id()) != null) {
                     notifyDelegate(new HostEvent(HOST_REMOVED, host));
                 }
             }

@@ -291,8 +291,8 @@ public abstract class TopologyViewMessageHandlerBase extends UiMessageHandler {
     // Produces a host event message to the client.
     protected ObjectNode hostMessage(HostEvent event) {
         Host host = event.subject();
+        Host prevHost = event.prevSubject();
         String hostType = host.annotations().value(AnnotationKeys.TYPE);
-        HostLocation prevLoc = event.prevLocation();
 
         ObjectNode payload = objectNode()
                 .put("id", host.id().toString())
@@ -300,8 +300,8 @@ public abstract class TopologyViewMessageHandlerBase extends UiMessageHandler {
                 .put("ingress", compactLinkString(edgeLink(host, true)))
                 .put("egress", compactLinkString(edgeLink(host, false)));
         payload.set("cp", hostConnect(host.location()));
-        if (prevLoc != null) {
-            payload.set("prevCp", hostConnect(event.prevLocation()));
+        if (prevHost != null && prevHost.location() != null) {
+            payload.set("prevCp", hostConnect(prevHost.location()));
         }
         payload.set("labels", labels(ip(host.ipAddresses()),
                                      host.mac().toString()));