Introduce a convenience method inSameIsland, which is the same as...

Introduce a convenience method inSameIsland, which is the same as inSameCluster.  In future, they may have different functionalities.

src/main/java/net/floodlightcontroller/routing/ForwardingBase.java

@@ -89,7 +89,15 @@ public abstract class ForwardingBase implements IOFMessageListener, IDeviceManag
             return d1ClusterId.compareTo(d2ClusterId);
         }
     };
-    
+
+    // Comparator for sorting the attachment points by last seen.
+    public Comparator<DeviceAttachmentPoint> lastSeenComparator = new Comparator<DeviceAttachmentPoint>() {
+        @Override
+        public int compare(DeviceAttachmentPoint d1, DeviceAttachmentPoint d2) {
+            return d1.getLastSeen().compareTo(d2.getLastSeen());
+        }
+    };
+
     /**
       * All subclasses must define this function if they want any specific forwarding action
      * @param sw Switch that the packet came in from

src/main/java/net/floodlightcontroller/topology/ITopologyService.java

@@ -36,6 +36,15 @@ public interface ITopologyService extends IFloodlightService  {
      */
     public boolean inSameCluster(long switch1, long switch2);
 
+    /**
+     * Queries whether two switches are in the same island.
+     * Currently, island and cluster are the same. In future,
+     * islands could be different than clusters.
+     * @param switch1
+     * @param switch2
+     * @return
+     */
+    public boolean inSameIsland(long switch1, long switch2);
 
     public void addListener(ITopologyListener listener);
 
@@ -56,7 +65,7 @@ public interface ITopologyService extends IFloodlightService  {
                                                          short srcPort,
                                                          long dst,
                                                          short dstPort);
-    
+
     public boolean isIncomingBroadcastAllowed(long sw, short portId);
 
     public boolean isInSameBroadcastDomain(long s1, short p1, long s2, short p2);

src/main/java/net/floodlightcontroller/topology/TopologyInstance.java

@@ -540,6 +540,10 @@ public class TopologyInstance {
         return false;
     }
 
+    public boolean inSameIsland(long switch1, long switch2) {
+        return inSameCluster(switch1, switch2);
+    }
+
     public NodePortTuple getOutgoingSwitchPort(long src, short srcPort,
                                                long dst, short dstPort) {
         // Use this function to redirect traffic if needed.

src/main/java/net/floodlightcontroller/topology/TopologyManager.java

@@ -441,5 +441,10 @@ IRoutingService, ILinkDiscoveryListener {
                                 short newPort) {
         return currentInstance.isConsistent(oldSw, oldPort, newSw, newPort);
     }
+
+    @Override
+    public boolean inSameIsland(long switch1, long switch2) {
+        return currentInstance.inSameIsland(switch1, switch2);
+    }
 }