Implemented a globally unique next id generator in FlowObjectStore

Change-Id: Ib98b2996e1ebcca56ad816ea94f25d838c5f4d44

@@ -348,7 +348,7 @@ public class BgpRouter {
             groupService.addGroup(groupDescription);
             */
 
-            nextHops.put(nextHop.ip(), entry.hashCode());
+            nextHops.put(nextHop.ip(), flowObjectiveService.allocateNextId());
 
         }
 

@@ -47,4 +47,10 @@ public interface FlowObjectiveService {
      */
     void next(DeviceId deviceId, NextObjective nextObjective);
 
+    /**
+     * Obtains a globally unique next objective.
+     * @return an integer
+     */
+    int allocateNextId();
+
 }

@@ -38,4 +38,11 @@ public interface FlowObjectiveStore
      * @return a next group
      */
     NextGroup getNextGroup(Integer nextId);
+
+    /**
+     * Allocates a next objective id. This id is globally unique
+     *
+     * @return an integer
+     */
+    int allocateNextId();
 }

@@ -170,6 +170,11 @@ public class FlowObjectiveManager implements FlowObjectiveService {
         }
     }
 
+    @Override
+    public int allocateNextId() {
+        return flowObjectiveStore.allocateNextId();
+    }
+
     private boolean queueObjective(DeviceId deviceId, ForwardingObjective fwd) {
         if (fwd.nextId() != null &&
                 flowObjectiveStore.getNextGroup(fwd.nextId()) == null) {

@@ -28,6 +28,7 @@ import org.onosproject.net.flowobjective.FlowObjectiveStore;
 import org.onosproject.net.flowobjective.FlowObjectiveStoreDelegate;
 import org.onosproject.net.flowobjective.ObjectiveEvent;
 import org.onosproject.store.AbstractStore;
+import org.onosproject.store.service.AtomicCounter;
 import org.onosproject.store.service.ConsistentMap;
 import org.onosproject.store.service.Serializer;
 import org.onosproject.store.service.StorageService;
@@ -52,6 +53,8 @@ public class DistributedFlowObjectiveStore
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected StorageService storageService;
 
+    private AtomicCounter nextIds;
+
     @Activate
     public void activate() {
         nextGroups = storageService.<Integer, byte[]>consistentMapBuilder()
@@ -62,6 +65,10 @@ public class DistributedFlowObjectiveStore
                                 .build()))
                 .build();
 
+        nextIds = storageService.atomicCounterBuilder()
+                .withName("next-objective-counter")
+                .build();
+
         log.info("Started");
     }
 
@@ -86,4 +93,9 @@ public class DistributedFlowObjectiveStore
         }
         return null;
     }
+
+    @Override
+    public int allocateNextId() {
+        return (int) nextIds.incrementAndGet();
+    }
 }