LeadershipStore updates:

 - Now tracking leader and candidates for a topic using a single map.
 - Using term numbers that are incremented by one every time a new leader is elected.
 - Introduced a separate LeadershipStore to conform to the  manager-store pattern

Change-Id: I1d03a6c5e8ff0e68ef0c1e3a6c2d425c4856e470

@@ -16,6 +16,7 @@
 package org.onosproject.cip;
 
 import com.google.common.io.ByteStreams;
+
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
@@ -93,7 +94,7 @@ public class ClusterIpManager {
         cfgService.registerProperties(getClass());
 
         localId = clusterService.getLocalNode().id();
-        processLeadershipChange(leadershipService.getLeader(CLUSTER_IP));
+        processLeaderChange(leadershipService.getLeader(CLUSTER_IP));
 
         leadershipService.addListener(listener);
         leadershipService.runForLeadership(CLUSTER_IP);
@@ -137,10 +138,7 @@ public class ClusterIpManager {
         }
     }
 
-    private synchronized void processLeadershipChange(NodeId newLeader) {
-        if (newLeader == null) {
-            return;
-        }
+    private synchronized void processLeaderChange(NodeId newLeader) {
         boolean isLeader = Objects.equals(newLeader, localId);
         log.info("Processing leadership change; wasLeader={}, isLeader={}", wasLeader, isLeader);
         if (!wasLeader && isLeader) {
@@ -189,11 +187,15 @@ public class ClusterIpManager {
 
     // Listens for leadership changes.
     private class InternalLeadershipListener implements LeadershipEventListener {
+
+        @Override
+        public boolean isRelevant(LeadershipEvent event) {
+            return CLUSTER_IP.equals(event.subject().topic());
+        }
+
         @Override
         public void event(LeadershipEvent event) {
-            if (event.subject().topic().equals(CLUSTER_IP)) {
-                processLeadershipChange(event.subject().leader());
-            }
+             processLeaderChange(event.subject().leaderNodeId());
         }
     }
 

@@ -19,6 +19,7 @@ package org.onosproject.mlb;
 import com.google.common.util.concurrent.ListenableScheduledFuture;
 import com.google.common.util.concurrent.ListeningScheduledExecutorService;
 import com.google.common.util.concurrent.MoreExecutors;
+
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
@@ -105,10 +106,7 @@ public class MastershipLoadBalancer {
         log.info("Stopped");
     }
 
-    private synchronized void processLeadershipChange(NodeId newLeader) {
-        if (newLeader == null) {
-            return;
-        }
+    private synchronized void processLeaderChange(NodeId newLeader) {
         boolean currLeader = newLeader.equals(localId);
         if (isLeader.getAndSet(currLeader) != currLeader) {
             if (currLeader) {
@@ -159,7 +157,7 @@ public class MastershipLoadBalancer {
 
         @Override
         public void event(LeadershipEvent event) {
-            processLeadershipChange(event.subject().leader());
+            processLeaderChange(event.subject().leaderNodeId());
         }
     }
-}
\ No newline at end of file
+}

@@ -26,6 +26,7 @@ import org.onosproject.cluster.ClusterService;
 import org.onosproject.cluster.LeadershipEvent;
 import org.onosproject.cluster.LeadershipEventListener;
 import org.onosproject.cluster.LeadershipService;
+import org.onosproject.cluster.NodeId;
 import org.onosproject.core.ApplicationId;
 import org.onosproject.core.CoreService;
 import org.onosproject.net.intent.Intent;
@@ -43,7 +44,6 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
-import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutorService;
 
@@ -74,6 +74,7 @@ public class IntentSynchronizer implements IntentSynchronizationService,
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected IntentService intentService;
 
+    private NodeId localNodeId;
     private ApplicationId appId;
 
     private final InternalLeadershipListener leadershipEventListener =
@@ -89,7 +90,7 @@ public class IntentSynchronizer implements IntentSynchronizationService,
     @Activate
     public void activate() {
         intentsSynchronizerExecutor = createExecutor();
-
+        this.localNodeId = clusterService.getLocalNode().id();
         this.appId = coreService.registerApplication(APP_NAME);
 
         leadershipService.addListener(leadershipEventListener);
@@ -268,27 +269,22 @@ public class IntentSynchronizer implements IntentSynchronizationService,
     private class InternalLeadershipListener implements LeadershipEventListener {
 
         @Override
-        public void event(LeadershipEvent event) {
-            if (!event.subject().topic().equals(appId.name())) {
-                // Not our topic: ignore
-                return;
-            }
-            if (!Objects.equals(event.subject().leader(),
-                    clusterService.getLocalNode().id())) {
-                // The event is not about this instance: ignore
-                return;
-            }
+        public boolean isRelevant(LeadershipEvent event) {
+            return event.subject().topic().equals(appId.name());
+        }
 
+        @Override
+        public void event(LeadershipEvent event) {
             switch (event.type()) {
-            case LEADER_ELECTED:
-                log.info("IntentSynchronizer gained leadership");
-                leaderChanged(true);
-                break;
-            case LEADER_BOOTED:
-                log.info("IntentSynchronizer lost leadership");
-                leaderChanged(false);
-                break;
-            case LEADER_REELECTED:
+            case LEADER_CHANGED:
+            case LEADER_AND_CANDIDATES_CHANGED:
+                if (localNodeId.equals(event.subject().leaderNodeId())) {
+                    log.info("IntentSynchronizer gained leadership");
+                    leaderChanged(true);
+                } else {
+                    log.info("IntentSynchronizer leader changed. New leader is {}", event.subject().leaderNodeId());
+                    leaderChanged(false);
+                }
             default:
                 break;
             }

@@ -17,6 +17,7 @@ package org.onosproject.routing.impl;
 
 import com.google.common.collect.Sets;
 import com.google.common.util.concurrent.MoreExecutors;
+
 import org.junit.Before;
 import org.junit.Test;
 import org.onlab.junit.TestUtils;
@@ -29,7 +30,11 @@ import org.onlab.packet.IpPrefix;
 import org.onlab.packet.MacAddress;
 import org.onlab.packet.VlanId;
 import org.onosproject.TestApplicationId;
+import org.onosproject.cluster.ClusterServiceAdapter;
+import org.onosproject.cluster.ControllerNode;
+import org.onosproject.cluster.DefaultControllerNode;
 import org.onosproject.cluster.LeadershipServiceAdapter;
+import org.onosproject.cluster.NodeId;
 import org.onosproject.core.ApplicationId;
 import org.onosproject.core.CoreServiceAdapter;
 import org.onosproject.incubator.net.intf.Interface;
@@ -94,6 +99,9 @@ public class IntentSynchronizerTest extends AbstractIntentTest {
     private static final ApplicationId APPID =
             TestApplicationId.create("intent-sync-test");
 
+    private static final ControllerNode LOCAL_NODE =
+            new DefaultControllerNode(new NodeId("foo"), IpAddress.valueOf("127.0.0.1"));
+
     @Before
     public void setUp() throws Exception {
         super.setUp();
@@ -105,6 +113,7 @@ public class IntentSynchronizerTest extends AbstractIntentTest {
         intentSynchronizer = new TestIntentSynchronizer();
 
         intentSynchronizer.coreService = new TestCoreService();
+        intentSynchronizer.clusterService = new TestClusterService();
         intentSynchronizer.leadershipService = new TestLeadershipService();
         intentSynchronizer.intentService = intentService;
 
@@ -441,6 +450,13 @@ public class IntentSynchronizerTest extends AbstractIntentTest {
         }
     }
 
+    private class TestClusterService extends ClusterServiceAdapter {
+        @Override
+        public ControllerNode getLocalNode() {
+            return LOCAL_NODE;
+        }
+    }
+
     private class TestLeadershipService extends LeadershipServiceAdapter {
 
     }

@@ -24,12 +24,11 @@ import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.onosproject.cluster.ClusterService;
 import org.onosproject.core.CoreService;
-import org.onosproject.cluster.ControllerNode;
 import org.onosproject.cluster.LeadershipEvent;
 import org.onosproject.cluster.LeadershipEventListener;
 import org.onosproject.cluster.LeadershipService;
+import org.onosproject.cluster.NodeId;
 import org.onosproject.core.ApplicationId;
-
 import org.slf4j.Logger;
 
 
@@ -56,7 +55,7 @@ public class ElectionTest {
     private LeadershipEventListener leadershipEventListener =
             new InnerLeadershipEventListener();
 
-    private ControllerNode localControllerNode;
+    private NodeId localNodeId;
 
 
     @Activate
@@ -65,7 +64,7 @@ public class ElectionTest {
 
         appId = coreService.registerApplication(ELECTION_APP);
 
-        localControllerNode = clusterService.getLocalNode();
+        localNodeId = clusterService.getLocalNode().id();
 
         leadershipService.addListener(leadershipEventListener);
     }
@@ -100,20 +99,10 @@ public class ElectionTest {
             log.debug("Leadership Event: time = {} type = {} event = {}",
                     event.time(), event.type(), event);
 
-            if (!event.subject().leader().equals(
-                    localControllerNode.id())) {
-                return;         // The event is not about this instance: ignore
-            }
-
             switch (event.type()) {
-                case LEADER_ELECTED:
-                    log.info("Election-test app leader elected");
-                    break;
-                case LEADER_BOOTED:
-                    log.info("Election-test app lost election");
-                    break;
-                case LEADER_REELECTED:
-                    log.debug("Election-test app was re-elected");
+                case LEADER_CHANGED:
+                case LEADER_AND_CANDIDATES_CHANGED:
+                    log.info("Election-test app leader changed. New leadership: {}", event.subject());
                     break;
                 default:
                     break;

@@ -40,7 +40,7 @@ import com.fasterxml.jackson.databind.node.ArrayNode;
         description = "Finds the leader for particular topic.")
 public class LeaderCommand extends AbstractShellCommand {
 
-    private static final String FMT = "%-30s | %-15s | %-6s | %-10s |";
+    private static final String FMT = "%-30s | %-15s | %-5s | %-10s |";
     private static final String FMT_C = "%-30s | %-15s | %-19s |";
     private boolean allTopics;
     private Pattern pattern;
@@ -57,19 +57,8 @@ public class LeaderCommand extends AbstractShellCommand {
     /**
      * Compares leaders, sorting by toString() output.
      */
-    private Comparator<Leadership> leadershipComparator =
-            (e1, e2) -> {
-                if (e1.leader() == null && e2.leader() == null) {
-                    return 0;
-                }
-                if (e1.leader() == null) {
-                    return 1;
-                }
-                if (e2.leader() == null) {
-                    return -1;
-                }
-                return e1.leader().toString().compareTo(e2.leader().toString());
-            };
+    private Comparator<Leadership> leadershipComparator = (l1, l2) ->
+        String.valueOf(l1.leaderNodeId()).compareTo(String.valueOf(l2.leaderNodeId()));
 
     /**
      * Displays text representing the leaders.
@@ -78,18 +67,19 @@ public class LeaderCommand extends AbstractShellCommand {
      */
     private void displayLeaders(Map<String, Leadership> leaderBoard) {
         print("------------------------------------------------------------------------");
-        print(FMT, "Topic", "Leader", "Epoch", "Elected");
+        print(FMT, "Topic", "Leader", "Term", "Elected");
         print("------------------------------------------------------------------------");
 
         leaderBoard.values()
                 .stream()
                 .filter(l -> allTopics || pattern.matcher(l.topic()).matches())
+                .filter(l -> l.leader() != null)
                 .sorted(leadershipComparator)
                 .forEach(l -> print(FMT,
                         l.topic(),
-                        l.leader(),
-                        l.epoch(),
-                        Tools.timeAgo(l.electedTime())));
+                        l.leaderNodeId(),
+                        l.leader().term(),
+                        Tools.timeAgo(l.leader().termStartTime())));
         print("------------------------------------------------------------------------");
     }
 
@@ -110,7 +100,7 @@ public class LeaderCommand extends AbstractShellCommand {
                         Leadership l = leaderBoard.get(es.getKey());
                         print(FMT_C,
                             es.getKey(),
-                            l == null ? "null" : l.leader(),
+                            String.valueOf(l.leaderNodeId()),
                             // formatting hacks to get it into a table
                             list.get(0).toString());
                             list.subList(1, list.size()).forEach(n -> print(FMT_C, " ", " ", n));
@@ -134,10 +124,10 @@ public class LeaderCommand extends AbstractShellCommand {
                         result.add(
                             mapper.createObjectNode()
                                 .put("topic", l.topic())
-                                .put("leader", l.leader().toString())
+                                .put("leader", String.valueOf(l.leaderNodeId()))
                                 .put("candidates", l.candidates().toString())
-                                .put("epoch", l.epoch())
-                                .put("electedTime", Tools.timeAgo(l.electedTime()))));
+                                .put("epoch", l.leader().term())
+                                .put("epochStartTime", Tools.timeAgo(l.leader().termStartTime()))));
 
         return result;
     }

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.cluster;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.base.Objects;
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkArgument;
+
+/**
+ * Topic leader.
+ * <p>
+ * Identified by the {@link NodeId node identifier} and a monotonically increasing term number.
+ * The term number is incremented by one every time a new node is elected as leader.
+ * Also available is the system clock time at the instant when this node was elected as leader.
+ * Keep in mind though that as with any system clock based time stamps this particular information
+ * susceptible to clock skew and should only be relied on for simple diagnostic purposes.
+ */
+public class Leader {
+    private final NodeId nodeId;
+    private final long term;
+    private final long termStartTime;
+
+    public Leader(NodeId nodeId, long term, long termStartTime) {
+        this.nodeId = checkNotNull(nodeId);
+        checkArgument(term >= 0, "term must be non-negative");
+        this.term = term;
+        checkArgument(termStartTime >= 0, "termStartTime must be non-negative");
+        this.termStartTime = termStartTime;
+    }
+
+    /**
+     * Returns the identifier for of leader.
+     * @return node identifier
+     */
+    public NodeId nodeId() {
+        return nodeId;
+    }
+
+    /**
+     * Returns the leader's term.
+     * @return leader term
+     */
+    public long term() {
+        return term;
+    }
+
+    /**
+     * Returns the system time when the current leadership term started.
+     * @return current leader term start time
+     */
+    public long termStartTime() {
+        return termStartTime;
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (this == other) {
+            return true;
+        }
+        if (other != null && other instanceof Leader) {
+            Leader that = (Leader) other;
+            return Objects.equal(this.nodeId, that.nodeId) &&
+                    this.term ==  that.term &&
+                    this.termStartTime == that.termStartTime;
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(nodeId, term, termStartTime);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+            .add("nodeId", nodeId)
+            .add("term", term)
+            .add("termStartTime", termStartTime)
+            .toString();
+    }
+}

@@ -17,63 +17,31 @@ package org.onosproject.cluster;
 
 import java.util.Objects;
 import java.util.List;
-import java.util.Optional;
-
-import org.joda.time.DateTime;
 
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableList;
 
 /**
- * Abstract leadership concept. The information carried by this construct
- * include the topic of contention, the {@link NodeId}s of Nodes that could
- * become leader for the topic, the epoch when the term for a given leader
- * began, and the system time when the term began. Note:
- * <ul>
- * <li>The list of NodeIds may include the current leader at index 0, and the
- * rest in decreasing preference order.</li>
- * <li>The epoch is the logical age of a Leadership construct, and should be
- * used for comparing two Leaderships, but only of the same topic.</li>
- * <li>The leader may be null if its accuracy can't be guaranteed. This applies
- * to CANDIDATES_CHANGED events and candidate board contents.</li>
- * </ul>
+ * State of leadership for topic.
+ * <p>
+ * Provided by this construct is the current {@link Leader leader} and the list of
+ * {@link NodeId nodeId}s currently registered as candidates for election for the topic.
+ * Keep in mind that only registered candidates can become leaders.
  */
 public class Leadership {
 
     private final String topic;
-    private final Optional<NodeId> leader;
+    private final Leader leader;
     private final List<NodeId> candidates;
-    private final long epoch;
-    private final long electedTime;
-
-    public Leadership(String topic, NodeId leader, long epoch, long electedTime) {
-        this.topic = topic;
-        this.leader = Optional.of(leader);
-        this.candidates = ImmutableList.of(leader);
-        this.epoch = epoch;
-        this.electedTime = electedTime;
-    }
-
-    public Leadership(String topic, NodeId leader, List<NodeId> candidates,
-            long epoch, long electedTime) {
-        this.topic = topic;
-        this.leader = Optional.of(leader);
-        this.candidates = ImmutableList.copyOf(candidates);
-        this.epoch = epoch;
-        this.electedTime = electedTime;
-    }
 
-    public Leadership(String topic, List<NodeId> candidates,
-            long epoch, long electedTime) {
+    public Leadership(String topic, Leader leader, List<NodeId> candidates) {
         this.topic = topic;
-        this.leader = Optional.empty();
+        this.leader = leader;
         this.candidates = ImmutableList.copyOf(candidates);
-        this.epoch = epoch;
-        this.electedTime = electedTime;
     }
 
     /**
-     * The topic for which this leadership applies.
+     * Returns the leadership topic.
      *
      * @return leadership topic.
      */
@@ -82,57 +50,36 @@ public class Leadership {
     }
 
     /**
-     * The nodeId of leader for this topic.
+     * Returns the {@link NodeId nodeId} of the leader.
      *
-     * @return leader node.
+     * @return leader node identifier; will be null if there is no leader
      */
-    // This will return Optional<NodeId> in the future.
-    public NodeId leader() {
-        return leader.orElse(null);
+    public NodeId leaderNodeId() {
+        return leader == null ? null : leader.nodeId();
     }
 
     /**
-     * Returns an preference-ordered list of nodes that are in the leadership
-     * race for this topic.
+     * Returns the leader for this topic.
      *
-     * @return a list of NodeIds in priority-order, or an empty list.
+     * @return leader; will be null if there is no leader for topic
      */
-    public List<NodeId> candidates() {
-        return candidates;
-    }
-
-    /**
-     * The epoch when the leadership was assumed.
-     * <p>
-     * Comparing epochs is only appropriate for leadership events for the same
-     * topic. The system guarantees that for any given topic the epoch for a new
-     * term is higher (not necessarily by 1) than the epoch for any previous
-     * term.
-     *
-     * @return leadership epoch
-     */
-    public long epoch() {
-        return epoch;
+    public Leader leader() {
+        return leader;
     }
 
     /**
-     * The system time when the term started.
-     * <p>
-     * The elected time is initially set on the node coordinating
-     * the leader election using its local system time. Due to possible
-     * clock skew, relying on this value for determining event ordering
-     * is discouraged. Epoch is more appropriate for determining
-     * event ordering.
+     * Returns an preference-ordered list of nodes that are in the leadership
+     * race for this topic.
      *
-     * @return elected time.
+     * @return a list of NodeIds in priority-order, or an empty list.
      */
-    public long electedTime() {
-        return electedTime;
+    public List<NodeId> candidates() {
+        return candidates;
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(topic, leader, candidates, epoch, electedTime);
+        return Objects.hash(topic, leader, candidates);
     }
 
     @Override
@@ -144,9 +91,7 @@ public class Leadership {
             final Leadership other = (Leadership) obj;
             return Objects.equals(this.topic, other.topic) &&
                     Objects.equals(this.leader, other.leader) &&
-                    Objects.equals(this.candidates, other.candidates) &&
-                    Objects.equals(this.epoch, other.epoch) &&
-                    Objects.equals(this.electedTime, other.electedTime);
+                    Objects.equals(this.candidates, other.candidates);
         }
         return false;
     }
@@ -157,8 +102,6 @@ public class Leadership {
             .add("topic", topic)
             .add("leader", leader)
             .add("candidates", candidates)
-            .add("epoch", epoch)
-            .add("electedTime", new DateTime(electedTime))
             .toString();
     }
 }

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.cluster;
+
+/**
+ * Interface for administratively manipulating leadership assignments.
+ */
+public interface LeadershipAdminService {
+
+    /**
+     * Attempts to assign leadership for a topic to a specified node.
+     * @param topic leadership topic
+     * @param nodeId identifier of the node to be made leader
+     * @return true is the transfer was successfully executed. This method returns {@code false}
+     * if {@code nodeId} is not one of the candidates for for the topic.
+     */
+    boolean transferLeadership(String topic, NodeId nodeId);
+
+    /**
+     * Make a node to be the next leader by promoting it to top of candidate list.
+     * @param topic leadership topic
+     * @param nodeId identifier of node to be next leader
+     * @return {@code true} if nodeId is now the top candidate. This method returns {@code false}
+     * if {@code nodeId} is not one of the candidates for for the topic.
+     */
+    boolean promoteToTopOfCandidateList(String topic, NodeId nodeId);
+
+    /**
+     * Removes all active leadership registrations for a given node.
+     * <p>
+     * This method will also evict the node from leaderships that it currently owns.
+     * @param nodeId node identifier
+     */
+    void unregister(NodeId nodeId);
+}

@@ -27,33 +27,25 @@ import com.google.common.base.MoreObjects;
 public class LeadershipEvent extends AbstractEvent<LeadershipEvent.Type, Leadership> {
 
     /**
-     * Type of leadership-related events.
+     * Type of leadership events.
      */
     public enum Type {
         /**
-         * Signifies that the leader has been elected.
-         * The event subject is the new leader.
-         * This event does not guarantee accurate candidate information.
+         * Signifies a change in both the leader as well as change to the list of candidates. Keep in mind though that
+         * the first node entering the race will trigger this event as it will become a candidate and automatically get
+         * promoted to become leader.
          */
-        LEADER_ELECTED,
+        LEADER_AND_CANDIDATES_CHANGED,
 
         /**
-         * Signifies that the leader has been re-elected.
-         * The event subject is the leader.
-         * This event does not guarantee accurate candidate information.
+         * Signifies that the leader for a topic has changed.
          */
-        LEADER_REELECTED,
+        // TODO: We may not need this. We currently do not support a way for a current leader to step down
+        // while still reamining a candidate
+        LEADER_CHANGED,
 
         /**
-         * Signifies that the leader has been booted and lost leadership.
-         * The event subject is the former leader.
-         * This event does not guarantee accurate candidate information.
-         */
-        LEADER_BOOTED,
-
-        /**
-         * Signifies that the list of candidates for leadership for a topic has
-         * changed. This event does not guarantee accurate leader information.
+         * Signifies a change in the list of candidates for a topic.
          */
         CANDIDATES_CHANGED
     }

@@ -17,87 +17,73 @@ package org.onosproject.cluster;
 
 import org.onosproject.event.ListenerService;
 
+import com.google.common.base.Objects;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Maps;
+
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.CompletableFuture;
 
 /**
  * Service for leader election.
+ * <p>
  * Leadership contests are organized around topics. A instance can join the
  * leadership race for a topic or withdraw from a race it has previously joined.
+ * <p>
  * Listeners can be added to receive notifications asynchronously for various
  * leadership contests.
+ * <p>
+ * When a node gets elected as a leader for a topic, all nodes receive notifications
+ * indicating a change in leadership.
  */
 public interface LeadershipService
     extends ListenerService<LeadershipEvent, LeadershipEventListener> {
 
     /**
-     * Returns the current leader for the topic.
+     * Returns the {@link NodeId node identifier} that is the current leader for a topic.
      *
-     * @param path topic
-     * @return nodeId of the leader, null if so such topic exists.
+     * @param topic leadership topic
+     * @return node identifier of the current leader; {@code null} if there is no leader for the topic
      */
-    NodeId getLeader(String path);
+    default NodeId getLeader(String topic) {
+        Leadership leadership = getLeadership(topic);
+        return leadership == null ? null : leadership.leaderNodeId();
+    }
 
     /**
-     * Returns the current leadership info for the topic.
+     * Returns the current {@link Leadership leadership} for a topic.
      *
-     * @param path topic
-     * @return leadership info or null if so such topic exists.
+     * @param topic leadership topic
+     * @return leadership or {@code null} if no such topic exists
      */
-    Leadership getLeadership(String path);
+    Leadership getLeadership(String topic);
 
     /**
-     * Returns the set of topics owned by the specified node.
+     * Returns the set of topics owned by the specified {@link NodeId node}.
      *
-     * @param nodeId node Id.
+     * @param nodeId node identifier.
      * @return set of topics for which this node is the current leader.
      */
-    Set<String> ownedTopics(NodeId nodeId);
+    default Set<String> ownedTopics(NodeId nodeId) {
+        return Maps.filterValues(getLeaderBoard(), v -> Objects.equal(nodeId, v.leaderNodeId())).keySet();
+    }
 
     /**
-     * Joins the leadership contest.
+     * Enters a leadership contest.
      *
-     * @param path topic for which this controller node wishes to be a leader
+     * @param topic leadership topic
      * @return {@code Leadership} future
      */
-    CompletableFuture<Leadership> runForLeadership(String path);
+    Leadership runForLeadership(String topic);
 
     /**
      * Withdraws from a leadership contest.
      *
-     * @param path topic for which this controller node no longer wishes to be a leader
-     * @return future that is successfully completed when withdraw is done
-     */
-    CompletableFuture<Void> withdraw(String path);
-
-    /**
-     * If the local nodeId is the leader for specified topic, this method causes it to
-     * step down temporarily from leadership.
-     * <p>
-     * The node will continue to be in contention for leadership and can
-     * potentially become the leader again if and when it becomes the highest
-     * priority candidate
-     * <p>
-     * If the local nodeId is not the leader, this method will make no changes and
-     * simply return false.
-     *
-     * @param path topic for which this controller node should give up leadership
-     * @return true if this node stepped down from leadership, false otherwise
+     * @param topic leadership topic
      */
-    boolean stepdown(String path);
-
-    /**
-     * Moves the specified nodeId to the top of the candidates list for the topic.
-     * <p>
-     * If the node is not a candidate for this topic, this method will be a noop.
-     *
-     * @param path leadership topic
-     * @param nodeId nodeId to make the top candidate
-     * @return true if nodeId is now the top candidate, false otherwise
-     */
-    boolean makeTopCandidate(String path, NodeId nodeId);
+    void withdraw(String topic);
 
     /**
      * Returns the current leader board.
@@ -107,18 +93,22 @@ public interface LeadershipService
     Map<String, Leadership> getLeaderBoard();
 
     /**
-     * Returns the candidates for all known topics.
+     * Returns the candidate nodes for each topic.
      *
      * @return A mapping from topics to corresponding list of candidates.
      */
-    Map<String, List<NodeId>> getCandidates();
+    default Map<String, List<NodeId>> getCandidates() {
+        return ImmutableMap.copyOf(Maps.transformValues(getLeaderBoard(), v -> ImmutableList.copyOf(v.candidates())));
+    }
 
     /**
-     * Returns the candidates for a given topic.
+     * Returns the candidate nodes for a given topic.
      *
-     * @param path topic
-     * @return A lists of NodeIds, which may be empty.
+     * @param topic leadership topic
+     * @return A lists of {@link NodeId nodeIds}, which may be empty.
      */
-    List<NodeId> getCandidates(String path);
-
-}
+    default List<NodeId> getCandidates(String topic) {
+        Leadership leadership = getLeadership(topic);
+        return leadership == null ? ImmutableList.of() : ImmutableList.copyOf(leadership.candidates());
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.cluster;
+
+import java.util.Map;
+import org.onosproject.store.Store;
+
+/**
+ * Store interface for managing {@link LeadershipService} state.
+ */
+public interface LeadershipStore extends Store<LeadershipEvent, LeadershipStoreDelegate> {
+
+    /**
+     * Adds registration for the local instance to be leader for topic.
+     *
+     * @param topic leadership topic
+     * @return Updated leadership after operation is completed
+     */
+    Leadership addRegistration(String topic);
+
+    /**
+     * Unregisters the local instance from leadership contest for topic.
+     *
+     * @param topic leadership topic
+     */
+    void removeRegistration(String topic);
+
+    /**
+     * Unregisters an instance from all leadership contests.
+     *
+     * @param nodeId node identifier
+     */
+    void removeRegistration(NodeId nodeId);
+
+    /**
+     * Updates state so that given node is leader for a topic.
+     *
+     * @param topic leadership topic
+     * @param toNodeId identifier of the desired leader
+     * @return {@code true} if the transfer succeeded; {@code false} otherwise.
+     * This method can return {@code false} if the node is not registered for the topic
+     */
+    boolean moveLeadership(String topic, NodeId toNodeId);
+
+    /**
+     * Attempts to make a node the top candidate.
+     *
+     * @param topic leadership topic
+     * @param nodeId node identifier
+     * @return {@code true} if the specified node is now the top candidate.
+     * This method will return {@code false} if the node is not registered for the topic
+     */
+    boolean makeTopCandidate(String topic, NodeId nodeId);
+
+    /**
+     * Returns the current leadership for topic.
+     *
+     * @param topic leadership topic
+     * @return current leadership
+     */
+    Leadership getLeadership(String topic);
+
+    /**
+     * Return current leadership for all topics.
+     *
+     * @return topic to leadership mapping
+     */
+    Map<String, Leadership> getLeaderships();
+}
\ No newline at end of file

+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.cluster;
+
+import org.onosproject.store.StoreDelegate;
+
+/**
+ * {@link LeadershipStore} delegate abstraction.
+ */
+public interface LeadershipStoreDelegate extends StoreDelegate<LeadershipEvent> {
+}

@@ -15,6 +15,8 @@
  */
 package org.onosproject.cluster;
 
+import java.util.Arrays;
+
 import org.junit.Test;
 
 import com.google.common.testing.EqualsTester;
@@ -28,10 +30,11 @@ import static org.junit.Assert.assertThat;
 public class LeadershipEventTest {
     private final NodeId node1 = new NodeId("1");
     private final NodeId node2 = new NodeId("2");
-    private final Leadership lead1 = new Leadership("topic1", node1, 1L, 2L);
-    private final Leadership lead2 = new Leadership("topic1", node2, 1L, 2L);
+    private final Leadership lead1 = new Leadership("topic1", new Leader(node1, 1L, 2L), Arrays.asList(node1));
+    private final Leadership lead2 = new Leadership("topic1", new Leader(node1, 1L, 2L), Arrays.asList(node1, node2));
+    private final Leadership lead3 = new Leadership("topic1", new Leader(node2, 1L, 2L), Arrays.asList(node2));
     private final LeadershipEvent event1 =
-            new LeadershipEvent(LeadershipEvent.Type.LEADER_ELECTED, lead1);
+            new LeadershipEvent(LeadershipEvent.Type.LEADER_CHANGED, lead1);
     private final long time = System.currentTimeMillis();
     private final LeadershipEvent event2 =
             new LeadershipEvent(LeadershipEvent.Type.CANDIDATES_CHANGED,
@@ -40,11 +43,9 @@ public class LeadershipEventTest {
             new LeadershipEvent(LeadershipEvent.Type.CANDIDATES_CHANGED,
                     lead2, time);
     private final LeadershipEvent event3 =
-            new LeadershipEvent(LeadershipEvent.Type.LEADER_BOOTED, lead1);
+            new LeadershipEvent(LeadershipEvent.Type.LEADER_CHANGED, lead2);
     private final LeadershipEvent event4 =
-            new LeadershipEvent(LeadershipEvent.Type.LEADER_REELECTED, lead1);
-    private final LeadershipEvent event5 =
-            new LeadershipEvent(LeadershipEvent.Type.LEADER_REELECTED, lead2);
+            new LeadershipEvent(LeadershipEvent.Type.LEADER_AND_CANDIDATES_CHANGED, lead3);
 
     /**
      * Tests for proper operation of equals(), hashCode() and toString() methods.
@@ -56,7 +57,6 @@ public class LeadershipEventTest {
                 .addEqualityGroup(event2, sameAsEvent2)
                 .addEqualityGroup(event3)
                 .addEqualityGroup(event4)
-                .addEqualityGroup(event5)
                 .testEquals();
     }
 
@@ -65,7 +65,7 @@ public class LeadershipEventTest {
      */
     @Test
     public void checkConstruction() {
-        assertThat(event1.type(), is(LeadershipEvent.Type.LEADER_ELECTED));
+        assertThat(event1.type(), is(LeadershipEvent.Type.LEADER_CHANGED));
         assertThat(event1.subject(), is(lead1));
 
         assertThat(event2.time(), is(time));

@@ -18,7 +18,6 @@ package org.onosproject.cluster;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.CompletableFuture;
 
 /**
  * Test adapter for leadership service.
@@ -41,13 +40,12 @@ public class LeadershipServiceAdapter implements LeadershipService {
     }
 
     @Override
-    public CompletableFuture<Leadership> runForLeadership(String path) {
+    public Leadership runForLeadership(String path) {
         return null;
     }
 
     @Override
-    public CompletableFuture<Void> withdraw(String path) {
-        return null;
+    public void withdraw(String path) {
     }
 
     @Override
@@ -74,14 +72,4 @@ public class LeadershipServiceAdapter implements LeadershipService {
     public List<NodeId> getCandidates(String path) {
         return null;
     }
-
-    @Override
-    public boolean stepdown(String path) {
-        return false;
-    }
-
-    @Override
-    public boolean makeTopCandidate(String path, NodeId nodeId) {
-        return false;
-    }
 }
\ No newline at end of file

@@ -15,12 +15,13 @@
  */
 package org.onosproject.cluster;
 
+import java.util.Arrays;
+
 import org.junit.Test;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.testing.EqualsTester;
 
-import static org.hamcrest.Matchers.contains;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertThat;
@@ -31,16 +32,14 @@ import static org.junit.Assert.assertThat;
 public class LeadershipTest {
     private final NodeId node1 = new NodeId("1");
     private final NodeId node2 = new NodeId("2");
-    private final Leadership lead1 = new Leadership("topic1", node1, 1L, 2L);
-    private final Leadership sameAsLead1 = new Leadership("topic1", node1, 1L, 2L);
-    private final Leadership lead2 = new Leadership("topic2", node1, 1L, 2L);
-    private final Leadership lead3 = new Leadership("topic1", node1, 2L, 2L);
-    private final Leadership lead4 = new Leadership("topic1", node1, 3L, 2L);
-    private final Leadership lead5 = new Leadership("topic1", node1, 3L, 3L);
-    private final Leadership lead6 = new Leadership("topic1", node1,
-            ImmutableList.of(node2), 1L, 2L);
-    private final Leadership lead7 = new Leadership("topic1",
-            ImmutableList.of(node2), 1L, 2L);
+    private final Leadership lead1 = new Leadership("topic1", new Leader(node1, 1L, 2L), Arrays.asList(node1));
+    private final Leadership sameAsLead1 = new Leadership("topic1", new Leader(node1, 1L, 2L), Arrays.asList(node1));
+    private final Leadership lead2 = new Leadership("topic2", new Leader(node1, 1L, 2L), Arrays.asList(node1));
+    private final Leadership lead3 = new Leadership("topic1", new Leader(node1, 2L, 2L), Arrays.asList(node1));
+    private final Leadership lead4 = new Leadership("topic1", new Leader(node1, 3L, 2L), Arrays.asList(node1));
+    private final Leadership lead5 = new Leadership("topic1", new Leader(node1, 3L, 3L), Arrays.asList(node1));
+    private final Leadership lead6 = new Leadership("topic1", new Leader(node2, 1L, 2L), Arrays.asList(node2, node1));
+    private final Leadership lead7 = new Leadership("topic1", null, ImmutableList.of());
 
     /**
      * Tests for proper operation of equals(), hashCode() and toString() methods.
@@ -64,12 +63,10 @@ public class LeadershipTest {
      */
     @Test
     public void checkConstruction() {
-        assertThat(lead6.electedTime(), is(2L));
-        assertThat(lead6.epoch(), is(1L));
-        assertThat(lead6.leader(), is(node1));
+        assertThat(lead6.leader(), is(new Leader(node2, 1L, 2L)));
         assertThat(lead6.topic(), is("topic1"));
-        assertThat(lead6.candidates(), hasSize(1));
-        assertThat(lead6.candidates(), contains(node2));
+        assertThat(lead6.candidates(), hasSize(2));
+        assertThat(lead6.candidates().get(1), is(node1));
+        assertThat(lead6.candidates().get(0), is(node2));
     }
-
 }

@@ -17,20 +17,22 @@ package org.onosproject.store.trivial;
 
 import static com.google.common.base.Preconditions.checkArgument;
 
+import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.stream.Collectors;
 
+import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.apache.felix.scr.annotations.Service;
 import org.onosproject.cluster.ClusterService;
+import org.onosproject.cluster.Leader;
 import org.onosproject.cluster.Leadership;
 import org.onosproject.cluster.LeadershipEvent;
 import org.onosproject.cluster.LeadershipEvent.Type;
@@ -53,8 +55,15 @@ public class SimpleLeadershipManager implements LeadershipService {
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     private ClusterService clusterService;
 
+    private NodeId localNodeId;
+
     private Map<String, Boolean> elections = new ConcurrentHashMap<>();
 
+    @Activate
+    public void activate() {
+        localNodeId = clusterService.getLocalNode().id();
+    }
+
     @Override
     public NodeId getLeader(String path) {
         return elections.get(path) ? clusterService.getLocalNode().id() : null;
@@ -63,7 +72,8 @@ public class SimpleLeadershipManager implements LeadershipService {
     @Override
     public Leadership getLeadership(String path) {
         checkArgument(path != null);
-        return elections.get(path) ? new Leadership(path, clusterService.getLocalNode().id(), 0, 0) : null;
+        return elections.get(path) ?
+                new Leadership(path, new Leader(localNodeId, 0, 0), Arrays.asList(localNodeId)) : null;
     }
 
     @Override
@@ -77,23 +87,22 @@ public class SimpleLeadershipManager implements LeadershipService {
     }
 
     @Override
-    public CompletableFuture<Leadership> runForLeadership(String path) {
+    public Leadership runForLeadership(String path) {
         elections.put(path, true);
+        Leadership leadership = new Leadership(path, new Leader(localNodeId, 0, 0), Arrays.asList(localNodeId));
         for (LeadershipEventListener listener : listeners) {
-            listener.event(new LeadershipEvent(Type.LEADER_ELECTED,
-                    new Leadership(path, clusterService.getLocalNode().id(), 0, 0)));
+            listener.event(new LeadershipEvent(Type.LEADER_AND_CANDIDATES_CHANGED, leadership));
         }
-        return CompletableFuture.completedFuture(new Leadership(path, clusterService.getLocalNode().id(), 0, 0));
+        return leadership;
     }
 
     @Override
-    public CompletableFuture<Void> withdraw(String path) {
+    public void withdraw(String path) {
         elections.remove(path);
         for (LeadershipEventListener listener : listeners) {
-            listener.event(new LeadershipEvent(Type.LEADER_BOOTED,
-                    new Leadership(path, clusterService.getLocalNode().id(), 0, 0)));
+            listener.event(new LeadershipEvent(Type.LEADER_AND_CANDIDATES_CHANGED,
+                    new Leadership(path, null, Arrays.asList())));
         }
-        return CompletableFuture.completedFuture(null);
     }
 
     @Override
@@ -122,14 +131,4 @@ public class SimpleLeadershipManager implements LeadershipService {
     public List<NodeId> getCandidates(String path) {
         return null;
     }
-
-    @Override
-    public boolean stepdown(String path) {
-        throw new UnsupportedOperationException();
-    }
-
-    @Override
-    public boolean makeTopCandidate(String path, NodeId nodeId) {
-        throw new UnsupportedOperationException();
-    }
 }

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.cluster.impl;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+import java.util.Map;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.apache.felix.scr.annotations.Service;
+import org.onlab.util.Tools;
+import org.onosproject.cluster.ClusterService;
+import org.onosproject.cluster.ControllerNode;
+import org.onosproject.cluster.Leadership;
+import org.onosproject.cluster.LeadershipAdminService;
+import org.onosproject.cluster.LeadershipEvent;
+import org.onosproject.cluster.LeadershipEventListener;
+import org.onosproject.cluster.LeadershipService;
+import org.onosproject.cluster.LeadershipStore;
+import org.onosproject.cluster.LeadershipStoreDelegate;
+import org.onosproject.cluster.NodeId;
+import org.onosproject.event.AbstractListenerManager;
+import org.slf4j.Logger;
+
+import com.google.common.collect.Maps;
+
+/**
+ * Implementation of {@link LeadershipService} and {@link LeadershipAdminService}.
+ */
+@Component(immediate = true)
+@Service
+public class LeadershipManager
+    extends AbstractListenerManager<LeadershipEvent, LeadershipEventListener>
+    implements LeadershipService, LeadershipAdminService {
+
+    private final Logger log = getLogger(getClass());
+
+    private LeadershipStoreDelegate delegate = this::post;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ClusterService clusterService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected LeadershipStore store;
+
+    private NodeId localNodeId;
+
+    private final ScheduledExecutorService deadlockDetector =
+            Executors.newSingleThreadScheduledExecutor(Tools.groupedThreads("onos/leadership", ""));
+
+    @Activate
+    public void activate() {
+        localNodeId = clusterService.getLocalNode().id();
+        store.setDelegate(delegate);
+        eventDispatcher.addSink(LeadershipEvent.class, listenerRegistry);
+        deadlockDetector.scheduleWithFixedDelay(() -> clusterService.getNodes()
+                .stream()
+                .map(ControllerNode::id)
+                .filter(id -> clusterService.getState(id) != ControllerNode.State.ACTIVE)
+                .forEach(this::unregister), 0, 2, TimeUnit.SECONDS);
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        deadlockDetector.shutdown();
+        Maps.filterValues(store.getLeaderships(), v -> v.candidates().contains(localNodeId))
+            .keySet()
+            .forEach(this::withdraw);
+        store.unsetDelegate(delegate);
+        eventDispatcher.removeSink(LeadershipEvent.class);
+        log.info("Stopped");
+    }
+
+    @Override
+    public Leadership getLeadership(String topic) {
+        return store.getLeadership(topic);
+    }
+
+    @Override
+    public Leadership runForLeadership(String topic) {
+        return store.addRegistration(topic);
+    }
+
+    @Override
+    public void withdraw(String topic) {
+        store.removeRegistration(topic);
+    }
+
+    @Override
+    public Map<String, Leadership> getLeaderBoard() {
+        return store.getLeaderships();
+    }
+
+    @Override
+    public boolean transferLeadership(String topic, NodeId to) {
+        return store.moveLeadership(topic, to);
+    }
+
+    @Override
+    public void unregister(NodeId nodeId) {
+        store.removeRegistration(nodeId);
+    }
+
+    @Override
+    public boolean promoteToTopOfCandidateList(String topic, NodeId nodeId) {
+        return store.makeTopCandidate(topic, nodeId);
+    }
+}

@@ -21,8 +21,6 @@ import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.apache.felix.scr.annotations.Service;
-import org.onosproject.cluster.ClusterEvent;
-import org.onosproject.cluster.ClusterEventListener;
 import org.onosproject.cluster.ClusterService;
 import org.onosproject.cluster.ControllerNode;
 import org.onosproject.cluster.Leadership;
@@ -76,7 +74,6 @@ public class IntentPartitionManager implements IntentPartitionService {
 
     private ListenerRegistry<IntentPartitionEvent, IntentPartitionEventListener> listenerRegistry;
     private LeadershipEventListener leaderListener = new InternalLeadershipListener();
-    private ClusterEventListener clusterListener = new InternalClusterEventListener();
 
     private ScheduledExecutorService executor = Executors
             .newScheduledThreadPool(1);
@@ -84,7 +81,6 @@ public class IntentPartitionManager implements IntentPartitionService {
     @Activate
     public void activate() {
         leadershipService.addListener(leaderListener);
-        clusterService.addListener(clusterListener);
 
         listenerRegistry = new ListenerRegistry<>();
         eventDispatcher.addSink(IntentPartitionEvent.class, listenerRegistry);
@@ -103,7 +99,6 @@ public class IntentPartitionManager implements IntentPartitionService {
 
         eventDispatcher.removeSink(IntentPartitionEvent.class);
         leadershipService.removeListener(leaderListener);
-        clusterService.removeListener(clusterListener);
     }
 
     /**
@@ -180,7 +175,7 @@ public class IntentPartitionManager implements IntentPartitionService {
 
         List<Leadership> myPartitions = leadershipService.getLeaderBoard().values()
                 .stream()
-                .filter(l -> clusterService.getLocalNode().id().equals(l.leader()))
+                .filter(l -> clusterService.getLocalNode().id().equals(l.leaderNodeId()))
                 .filter(l -> l.topic().startsWith(ELECTION_PREFIX))
                 .collect(Collectors.toList());
 
@@ -220,24 +215,16 @@ public class IntentPartitionManager implements IntentPartitionService {
         public void event(LeadershipEvent event) {
             Leadership leadership = event.subject();
 
-            if (Objects.equals(leadership.leader(), clusterService.getLocalNode().id()) &&
+            if (Objects.equals(leadership.leaderNodeId(), clusterService.getLocalNode().id()) &&
                     leadership.topic().startsWith(ELECTION_PREFIX)) {
 
-                // See if we need to let some partitions go
-                scheduleRebalance(0);
-
                 eventDispatcher.post(new IntentPartitionEvent(IntentPartitionEvent.Type.LEADER_CHANGED,
                                                         leadership.topic()));
             }
-        }
-    }
 
-    private final class InternalClusterEventListener implements
-            ClusterEventListener {
-
-        @Override
-        public void event(ClusterEvent event) {
-            scheduleRebalance(0);
+            if (event.type() == LeadershipEvent.Type.CANDIDATES_CHANGED) {
+                scheduleRebalance(0);
+            }
         }
     }
 }

@@ -22,6 +22,7 @@ import org.onlab.packet.IpAddress;
 import org.onosproject.cluster.ClusterServiceAdapter;
 import org.onosproject.cluster.ControllerNode;
 import org.onosproject.cluster.DefaultControllerNode;
+import org.onosproject.cluster.Leader;
 import org.onosproject.cluster.Leadership;
 import org.onosproject.cluster.LeadershipEvent;
 import org.onosproject.cluster.LeadershipEventListener;
@@ -31,13 +32,12 @@ import org.onosproject.cluster.NodeId;
 import org.onosproject.common.event.impl.TestEventDispatcher;
 import org.onosproject.net.intent.Key;
 
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
-import java.util.concurrent.CompletableFuture;
-
 import static junit.framework.TestCase.assertFalse;
 import static org.easymock.EasyMock.anyObject;
 import static org.easymock.EasyMock.anyString;
@@ -55,9 +55,10 @@ import static org.junit.Assert.assertTrue;
 public class IntentPartitionManagerTest {
 
     private final LeadershipEvent event
-            = new LeadershipEvent(LeadershipEvent.Type.LEADER_ELECTED,
+            = new LeadershipEvent(LeadershipEvent.Type.CANDIDATES_CHANGED,
                                   new Leadership(ELECTION_PREFIX + "0",
-                                                 MY_NODE_ID, 0, 0));
+                                                 new Leader(MY_NODE_ID, 0, 0),
+                                                 Arrays.asList(MY_NODE_ID, OTHER_NODE_ID)));
 
     private static final NodeId MY_NODE_ID = new NodeId("local");
     private static final NodeId OTHER_NODE_ID = new NodeId("other");
@@ -78,7 +79,7 @@ public class IntentPartitionManagerTest {
         expectLastCall().andDelegateTo(new TestLeadershipService());
         for (int i = 0; i < IntentPartitionManager.NUM_PARTITIONS; i++) {
             expect(leadershipService.runForLeadership(ELECTION_PREFIX + i))
-                .andReturn(CompletableFuture.completedFuture(null))
+                .andReturn(null)
                 .times(1);
         }
 
@@ -105,7 +106,9 @@ public class IntentPartitionManagerTest {
             expect(leadershipService.getLeader(ELECTION_PREFIX + i))
                     .andReturn(MY_NODE_ID).anyTimes();
             leaderBoard.put(ELECTION_PREFIX + i,
-                            new Leadership(ELECTION_PREFIX + i, MY_NODE_ID, 0, 0));
+                            new Leadership(ELECTION_PREFIX + i,
+                                    new Leader(MY_NODE_ID, 0, 0),
+                                    Arrays.asList(MY_NODE_ID)));
         }
 
         for (int i = numMine; i < IntentPartitionManager.NUM_PARTITIONS; i++) {
@@ -113,7 +116,9 @@ public class IntentPartitionManagerTest {
                     .andReturn(OTHER_NODE_ID).anyTimes();
 
             leaderBoard.put(ELECTION_PREFIX + i,
-                            new Leadership(ELECTION_PREFIX + i, OTHER_NODE_ID, 0, 0));
+                            new Leadership(ELECTION_PREFIX + i,
+                                    new Leader(OTHER_NODE_ID, 0, 0),
+                                    Arrays.asList(OTHER_NODE_ID)));
         }
 
         expect(leadershipService.getLeaderBoard()).andReturn(leaderBoard).anyTimes();
@@ -131,7 +136,7 @@ public class IntentPartitionManagerTest {
 
         for (int i = 0; i < IntentPartitionManager.NUM_PARTITIONS; i++) {
             expect(leadershipService.runForLeadership(ELECTION_PREFIX + i))
-                .andReturn(CompletableFuture.completedFuture(null))
+                .andReturn(null)
                 .times(1);
         }
 
@@ -200,9 +205,8 @@ public class IntentPartitionManagerTest {
         // We have all the partitions so we'll need to relinquish some
         setUpLeadershipService(IntentPartitionManager.NUM_PARTITIONS);
 
-        expect(leadershipService.withdraw(anyString()))
-                                 .andReturn(CompletableFuture.completedFuture(null))
-                                 .times(7);
+        leadershipService.withdraw(anyString());
+        expectLastCall().times(7);
 
         replay(leadershipService);