Code clean up in ConsistentMap and LeaderElector resources

Change-Id: I1834188393f19e37394c32047538e6027522a13d

@@ -29,6 +29,15 @@ import java.util.function.Consumer;
 import org.onosproject.cluster.Leadership;
 import org.onosproject.cluster.NodeId;
 import org.onosproject.event.Change;
+import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorCommands.Anoint;
+import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorCommands.GetAllLeaderships;
+import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorCommands.GetElectedTopics;
+import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorCommands.GetLeadership;
+import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorCommands.Listen;
+import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorCommands.Promote;
+import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorCommands.Run;
+import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorCommands.Unlisten;
+import org.onosproject.store.primitives.resources.impl.AtomixLeaderElectorCommands.Withdraw;
 import org.onosproject.store.service.AsyncLeaderElector;
 
 import com.google.common.collect.Sets;
@@ -70,22 +79,22 @@ public class AtomixLeaderElector extends Resource<AtomixLeaderElector>
 
     @Override
     public CompletableFuture<Leadership> run(String topic, NodeId nodeId) {
-        return submit(new AtomixLeaderElectorCommands.Run(topic, nodeId));
+        return submit(new Run(topic, nodeId));
     }
 
     @Override
     public CompletableFuture<Void> withdraw(String topic) {
-        return submit(new AtomixLeaderElectorCommands.Withdraw(topic));
+        return submit(new Withdraw(topic));
     }
 
     @Override
     public CompletableFuture<Boolean> anoint(String topic, NodeId nodeId) {
-        return submit(new AtomixLeaderElectorCommands.Anoint(topic, nodeId));
+        return submit(new Anoint(topic, nodeId));
     }
 
     @Override
     public CompletableFuture<Boolean> promote(String topic, NodeId nodeId) {
-        return submit(new AtomixLeaderElectorCommands.Promote(topic, nodeId));
+        return submit(new Promote(topic, nodeId));
     }
 
     @Override
@@ -95,69 +104,32 @@ public class AtomixLeaderElector extends Resource<AtomixLeaderElector>
 
     @Override
     public CompletableFuture<Leadership> getLeadership(String topic) {
-        return submit(new AtomixLeaderElectorCommands.GetLeadership(topic));
+        return submit(new GetLeadership(topic));
     }
 
     @Override
     public CompletableFuture<Map<String, Leadership>> getLeaderships() {
-        return submit(new AtomixLeaderElectorCommands.GetAllLeaderships());
+        return submit(new GetAllLeaderships());
     }
 
     public CompletableFuture<Set<String>> getElectedTopics(NodeId nodeId) {
-        return submit(new AtomixLeaderElectorCommands.GetElectedTopics(nodeId));
-    }
-
-    /**
-     * Leadership change listener context.
-     */
-    private final class LeadershipChangeListener implements Listener<Change<Leadership>> {
-        private final Consumer<Change<Leadership>> listener;
-
-        private LeadershipChangeListener(Consumer<Change<Leadership>> listener) {
-            this.listener = listener;
-        }
-
-        @Override
-        public void accept(Change<Leadership> change) {
-            listener.accept(change);
-        }
-
-        @Override
-        public void close() {
-            synchronized (AtomixLeaderElector.this) {
-                submit(new AtomixLeaderElectorCommands.Unlisten());
-            }
-        }
+        return submit(new GetElectedTopics(nodeId));
     }
 
     @Override
-    public CompletableFuture<Void> addChangeListener(Consumer<Change<Leadership>> consumer) {
+    public synchronized CompletableFuture<Void> addChangeListener(Consumer<Change<Leadership>> consumer) {
+        if (leadershipChangeListeners.isEmpty()) {
+            return submit(new Listen()).thenRun(() -> leadershipChangeListeners.add(consumer));
+        } else {
             leadershipChangeListeners.add(consumer);
-        return setupListener();
-    }
-
-    @Override
-    public CompletableFuture<Void> removeChangeListener(Consumer<Change<Leadership>> consumer) {
-        leadershipChangeListeners.remove(consumer);
-        return teardownListener();
-    }
-
-    private CompletableFuture<Void> setupListener() {
-        if (listener == null && !leadershipChangeListeners.isEmpty()) {
-            Consumer<Change<Leadership>> changeConsumer = change -> {
-                leadershipChangeListeners.forEach(consumer -> consumer.accept(change));
-            };
-            return submit(new AtomixLeaderElectorCommands.Listen())
-                    .thenAccept(v -> listener = new LeadershipChangeListener(changeConsumer));
-        }
             return CompletableFuture.completedFuture(null);
         }
+    }
 
-    private CompletableFuture<Void> teardownListener() {
-        if (listener != null && leadershipChangeListeners.isEmpty()) {
-            listener.close();
-            listener = null;
-            return submit(new AtomixLeaderElectorCommands.Unlisten());
+    @Override
+    public synchronized CompletableFuture<Void> removeChangeListener(Consumer<Change<Leadership>> consumer) {
+        if (leadershipChangeListeners.remove(listener) && leadershipChangeListeners.isEmpty()) {
+            return submit(new Unlisten()).thenApply(v -> null);
         }
         return CompletableFuture.completedFuture(null);
     }