Ensure one can add/remove status change listeners for LeaderElectors

Change-Id: Ief362489fe9b563606f07d52c300629af23b6372
(cherry picked from commit d7ff34d6)

@@ -15,6 +15,7 @@
  */
 package org.onosproject.store.primitives;
 
+import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
@@ -89,6 +90,21 @@ public class DefaultLeaderElector extends Synchronous<AsyncLeaderElector> implem
         complete(asyncElector.removeChangeListener(consumer));
     }
 
+    @Override
+    public void addStatusChangeListener(Consumer<Status> listener) {
+        asyncElector.addStatusChangeListener(listener);
+    }
+
+    @Override
+    public void removeStatusChangeListener(Consumer<Status> listener) {
+        asyncElector.removeStatusChangeListener(listener);
+    }
+
+    @Override
+    public Collection<Consumer<Status>> statusChangeListeners() {
+        return asyncElector.statusChangeListeners();
+    }
+
     private <T> T complete(CompletableFuture<T> future) {
         try {
             return future.get(operationTimeoutMillis, TimeUnit.MILLISECONDS);

@@ -19,6 +19,7 @@ import io.atomix.copycat.client.CopycatClient;
 import io.atomix.resource.AbstractResource;
 import io.atomix.resource.ResourceTypeInfo;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
@@ -40,6 +41,7 @@ import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorComman
 import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorCommands.Withdraw;
 import org.onosproject.store.service.AsyncLeaderElector;
 
+import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
 
 /**
@@ -48,8 +50,10 @@ import com.google.common.collect.Sets;
 @ResourceTypeInfo(id = -152, factory = AtomixLeaderElectorFactory.class)
 public class AtomixLeaderElector extends AbstractResource<AtomixLeaderElector>
     implements AsyncLeaderElector {
+    private final Set<Consumer<Status>> statusChangeListeners =
+            Sets.newCopyOnWriteArraySet();
     private final Set<Consumer<Change<Leadership>>> leadershipChangeListeners =
-            Sets.newIdentityHashSet();
+            Sets.newCopyOnWriteArraySet();
 
     public static final String CHANGE_SUBJECT = "leadershipChangeEvents";
 
@@ -130,4 +134,19 @@ public class AtomixLeaderElector extends AbstractResource<AtomixLeaderElector>
         }
         return CompletableFuture.completedFuture(null);
     }
+
+    @Override
+    public void addStatusChangeListener(Consumer<Status> listener) {
+        statusChangeListeners.add(listener);
+    }
+
+    @Override
+    public void removeStatusChangeListener(Consumer<Status> listener) {
+        statusChangeListeners.remove(listener);
+    }
+
+    @Override
+    public Collection<Consumer<Status>> statusChangeListeners() {
+        return ImmutableSet.copyOf(statusChangeListeners);
+    }
 }