role reassignment tweaks

Change-Id: Ie6d412787330e67a13e605a34f0824cf70882f85

@@ -33,7 +33,7 @@ public interface MastershipService {
     /**
     /**
      * Abandons mastership of the specified device on the local node thus
      * Abandons mastership of the specified device on the local node thus
      * forcing selection of a new master. If the local node is not a master
      * forcing selection of a new master. If the local node is not a master
-     * for this device, no action will be taken.
+     * for this device, no master selection will occur.
      *
      *
      * @param deviceId the identifier of the device
      * @param deviceId the identifier of the device
      */
      */

@@ -66,12 +66,25 @@ public interface MastershipStore extends Store<MastershipEvent, MastershipStoreD
     MastershipTerm getTermFor(DeviceId deviceId);
     MastershipTerm getTermFor(DeviceId deviceId);
 
 
     /**
     /**
-     * Revokes a controller instance's mastership over a device and hands
-     * over mastership to another controller instance.
+     * Sets a controller instance's mastership role to STANDBY for a device.
+     * If the role is MASTER, another controller instance will be selected
+     * as a candidate master.
      *
      *
      * @param nodeId   the controller instance identifier
      * @param nodeId   the controller instance identifier
-     * @param deviceId device to revoke mastership for
+     * @param deviceId device to revoke mastership role for
      * @return a mastership event
      * @return a mastership event
      */
      */
-    MastershipEvent unsetMaster(NodeId nodeId, DeviceId deviceId);
+    MastershipEvent setStandby(NodeId nodeId, DeviceId deviceId);
+
+    /**
+     * Allows a controller instance to give up its current role for a device.
+     * If the role is MASTER, another controller instance will be selected
+     * as a candidate master.
+     *
+     * @param nodeId   the controller instance identifier
+     * @param deviceId device to revoke mastership role for
+     * @return a mastership event
+     */
+    MastershipEvent relinquishRole(NodeId nodeId, DeviceId deviceId);
+
 }
 }

@@ -82,7 +82,7 @@ implements MastershipService, MastershipAdminService {
         if (role.equals(MastershipRole.MASTER)) {
         if (role.equals(MastershipRole.MASTER)) {
             event = store.setMaster(nodeId, deviceId);
             event = store.setMaster(nodeId, deviceId);
         } else {
         } else {
-            event = store.unsetMaster(nodeId, deviceId);
+            event = store.setStandby(nodeId, deviceId);
         }
         }
 
 
         if (event != null) {
         if (event != null) {
@@ -98,13 +98,10 @@ implements MastershipService, MastershipAdminService {
 
 
     @Override
     @Override
     public void relinquishMastership(DeviceId deviceId) {
     public void relinquishMastership(DeviceId deviceId) {
-        MastershipRole role = getLocalRole(deviceId);
-        if (!role.equals(MastershipRole.MASTER)) {
-            return;
-        }
-
-        MastershipEvent event = store.unsetMaster(
+        MastershipEvent event = null;
+            event = store.relinquishRole(
                     clusterService.getLocalNode().id(), deviceId);
                     clusterService.getLocalNode().id(), deviceId);
+
         if (event != null) {
         if (event != null) {
             post(event);
             post(event);
         }
         }

@@ -142,7 +142,7 @@ public class DeviceManager
 
 
     // Applies the specified role to the device; ignores NONE
     // Applies the specified role to the device; ignores NONE
     private void applyRole(DeviceId deviceId, MastershipRole newRole) {
     private void applyRole(DeviceId deviceId, MastershipRole newRole) {
-        if (newRole != MastershipRole.NONE) {
+        if (newRole.equals(MastershipRole.NONE)) {
             Device device = store.getDevice(deviceId);
             Device device = store.getDevice(deviceId);
             DeviceProvider provider = getProvider(device.providerId());
             DeviceProvider provider = getProvider(device.providerId());
             if (provider != null) {
             if (provider != null) {
@@ -196,11 +196,8 @@ public class DeviceManager
             DeviceEvent event = store.createOrUpdateDevice(provider().id(),
             DeviceEvent event = store.createOrUpdateDevice(provider().id(),
                     deviceId, deviceDescription);
                     deviceId, deviceDescription);
 
 
-            // If there was a change of any kind, trigger role selection
-            // process.
             if (event != null) {
             if (event != null) {
                 log.info("Device {} connected", deviceId);
                 log.info("Device {} connected", deviceId);
-                //mastershipService.requestRoleFor(deviceId);
                 provider().roleChanged(event.subject(),
                 provider().roleChanged(event.subject(),
                         mastershipService.requestRoleFor(deviceId));
                         mastershipService.requestRoleFor(deviceId));
                 post(event);
                 post(event);
@@ -212,11 +209,11 @@ public class DeviceManager
             checkNotNull(deviceId, DEVICE_ID_NULL);
             checkNotNull(deviceId, DEVICE_ID_NULL);
             checkValidity();
             checkValidity();
             DeviceEvent event = store.markOffline(deviceId);
             DeviceEvent event = store.markOffline(deviceId);
+            //we're no longer capable of being master or a candidate.
+            mastershipService.relinquishMastership(deviceId);
 
 
-            //we're no longer capable of mastership.
             if (event != null) {
             if (event != null) {
                 log.info("Device {} disconnected", deviceId);
                 log.info("Device {} disconnected", deviceId);
-                mastershipService.relinquishMastership(deviceId);
                 post(event);
                 post(event);
             }
             }
         }
         }
@@ -267,17 +264,23 @@ public class DeviceManager
     }
     }
 
 
     // Intercepts mastership events
     // Intercepts mastership events
-    private class InternalMastershipListener
-    implements MastershipListener {
+    private class InternalMastershipListener implements MastershipListener {
+
         @Override
         @Override
         public void event(MastershipEvent event) {
         public void event(MastershipEvent event) {
+            DeviceId did = event.subject();
+            if (isAvailable(did)) {
                 if (event.master().equals(clusterService.getLocalNode().id())) {
                 if (event.master().equals(clusterService.getLocalNode().id())) {
-                MastershipTerm term = mastershipService.requestTermService()
-                        .getMastershipTerm(event.subject());
-                clockService.setMastershipTerm(event.subject(), term);
-                applyRole(event.subject(), MastershipRole.MASTER);
+                    MastershipTerm term = termService.getMastershipTerm(did);
+                    clockService.setMastershipTerm(did, term);
+                    applyRole(did, MastershipRole.MASTER);
+                } else {
+                    applyRole(did, MastershipRole.STANDBY);
+                }
             } else {
             } else {
-                applyRole(event.subject(), MastershipRole.STANDBY);
+                //device dead to node, give up
+                mastershipService.relinquishMastership(did);
+                applyRole(did, MastershipRole.STANDBY);
             }
             }
         }
         }
     }
     }

 package org.onlab.onos.net.device.impl;
 package org.onlab.onos.net.device.impl;
 
 
 import com.google.common.collect.Sets;
 import com.google.common.collect.Sets;
+
 import org.junit.After;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Before;
 import org.junit.Ignore;
 import org.junit.Ignore;
@@ -258,7 +259,8 @@ public class DeviceManagerTest {
         }
         }
     }
     }
 
 
-    private static class TestMastershipService extends MastershipServiceAdapter {
+    private static class TestMastershipService
+            extends MastershipServiceAdapter {
         @Override
         @Override
         public MastershipRole getLocalRole(DeviceId deviceId) {
         public MastershipRole getLocalRole(DeviceId deviceId) {
             return MastershipRole.MASTER;
             return MastershipRole.MASTER;

@@ -10,7 +10,6 @@ import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
-import org.apache.felix.scr.annotations.ReferencePolicy;
 import org.apache.felix.scr.annotations.Service;
 import org.apache.felix.scr.annotations.Service;
 import org.onlab.onos.cluster.ClusterService;
 import org.onlab.onos.cluster.ClusterService;
 import org.onlab.onos.cluster.MastershipEvent;
 import org.onlab.onos.cluster.MastershipEvent;
@@ -20,15 +19,16 @@ import org.onlab.onos.cluster.MastershipTerm;
 import org.onlab.onos.cluster.NodeId;
 import org.onlab.onos.cluster.NodeId;
 import org.onlab.onos.net.DeviceId;
 import org.onlab.onos.net.DeviceId;
 import org.onlab.onos.net.MastershipRole;
 import org.onlab.onos.net.MastershipRole;
-import org.onlab.onos.net.device.DeviceService;
 import org.onlab.onos.store.common.AbstractHazelcastStore;
 import org.onlab.onos.store.common.AbstractHazelcastStore;
 
 
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSet;
 import com.hazelcast.core.ILock;
 import com.hazelcast.core.ILock;
 import com.hazelcast.core.IMap;
 import com.hazelcast.core.IMap;
+import com.hazelcast.core.MultiMap;
 
 
 /**
 /**
- * Distributed implementation of the cluster nodes store.
+ * Distributed implementation of the mastership store. The store is
+ * responsible for the master selection process.
  */
  */
 @Component(immediate = true)
 @Component(immediate = true)
 @Service
 @Service
@@ -38,35 +38,34 @@ implements MastershipStore {
 
 
     //arbitrary lock name
     //arbitrary lock name
     private static final String LOCK = "lock";
     private static final String LOCK = "lock";
-    //initial term value
+    //initial term/TTL value
     private static final Integer INIT = 0;
     private static final Integer INIT = 0;
-    //placeholder non-null value
-    private static final Byte NIL = 0x0;
 
 
     //devices to masters
     //devices to masters
-    protected IMap<byte[], byte[]> rawMasters;
+    protected IMap<byte[], byte[]> masters;
     //devices to terms
     //devices to terms
-    protected IMap<byte[], Integer> rawTerms;
-    //collection of nodes. values are ignored, as it's used as a makeshift 'set'
-    protected IMap<byte[], Byte> backups;
+    protected IMap<byte[], Integer> terms;
+
+    //re-election related, disjoint-set structures:
+    //device-nodes multiset of available nodes
+    protected MultiMap<byte[], byte[]> standbys;
+    //device-nodes multiset for nodes that have given up on device
+    protected MultiMap<byte[], byte[]> unusable;
 
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected ClusterService clusterService;
     protected ClusterService clusterService;
 
 
-    //FIXME: need to guarantee that this will be met, sans circular dependencies
-    @Reference(policy = ReferencePolicy.DYNAMIC)
-    protected DeviceService deviceService;
-
     @Override
     @Override
     @Activate
     @Activate
     public void activate() {
     public void activate() {
         super.activate();
         super.activate();
 
 
-        rawMasters = theInstance.getMap("masters");
-        rawTerms = theInstance.getMap("terms");
-        backups = theInstance.getMap("backups");
+        masters = theInstance.getMap("masters");
+        terms = theInstance.getMap("terms");
+        standbys = theInstance.getMultiMap("backups");
+        unusable = theInstance.getMultiMap("unusable");
 
 
-        rawMasters.addEntryListener(new RemoteMasterShipEventHandler(), true);
+        masters.addEntryListener(new RemoteMasterShipEventHandler(), true);
 
 
         log.info("Started");
         log.info("Started");
     }
     }
@@ -77,6 +76,30 @@ implements MastershipStore {
     }
     }
 
 
     @Override
     @Override
+    public MastershipRole getRole(NodeId nodeId, DeviceId deviceId) {
+        byte[] did = serialize(deviceId);
+        byte[] nid = serialize(nodeId);
+
+        NodeId current = deserialize(masters.get(did));
+        if (current == null) {
+            if (standbys.containsEntry(did, nid)) {
+                //was previously standby, or set to standby from master
+                return MastershipRole.STANDBY;
+            } else {
+                return MastershipRole.NONE;
+            }
+        } else {
+            if (current.equals(nodeId)) {
+                //*should* be in unusable, not always
+                return MastershipRole.MASTER;
+            } else {
+                //may be in backups or unusable from earlier retirement
+                return MastershipRole.STANDBY;
+            }
+        }
+    }
+
+    @Override
     public MastershipEvent setMaster(NodeId nodeId, DeviceId deviceId) {
     public MastershipEvent setMaster(NodeId nodeId, DeviceId deviceId) {
         byte [] did = serialize(deviceId);
         byte [] did = serialize(deviceId);
         byte [] nid = serialize(nodeId);
         byte [] nid = serialize(nodeId);
@@ -85,30 +108,31 @@ implements MastershipStore {
         lock.lock();
         lock.lock();
         try {
         try {
             MastershipRole role = getRole(nodeId, deviceId);
             MastershipRole role = getRole(nodeId, deviceId);
-            Integer term = rawTerms.get(did);
             switch (role) {
             switch (role) {
                 case MASTER:
                 case MASTER:
+                    //reinforce mastership
+                    evict(nid, did);
                     return null;
                     return null;
                 case STANDBY:
                 case STANDBY:
-                    rawMasters.put(did, nid);
-                    rawTerms.put(did, ++term);
-                    backups.putIfAbsent(nid, NIL);
-                    break;
-                case NONE:
-                    rawMasters.put(did, nid);
-                    //new switch OR state transition after being orphaned
-                    if (term == null) {
-                        rawTerms.put(did, INIT);
-                    } else {
-                        rawTerms.put(did, ++term);
+                    //make current master standby
+                    byte [] current = masters.get(did);
+                    if (current != null) {
+                        backup(current, did);
                     }
                     }
-                    backups.put(nid, NIL);
-                    break;
+                    //assign specified node as new master
+                    masters.put(did, nid);
+                    evict(nid, did);
+                    updateTerm(did);
+                    return new MastershipEvent(MASTER_CHANGED, deviceId, nodeId);
+                case NONE:
+                    masters.put(did, nid);
+                    evict(nid, did);
+                    updateTerm(did);
+                    return new MastershipEvent(MASTER_CHANGED, deviceId, nodeId);
                 default:
                 default:
                     log.warn("unknown Mastership Role {}", role);
                     log.warn("unknown Mastership Role {}", role);
                     return null;
                     return null;
             }
             }
-            return new MastershipEvent(MASTER_CHANGED, deviceId, nodeId);
         } finally {
         } finally {
             lock.unlock();
             lock.unlock();
         }
         }
@@ -116,14 +140,14 @@ implements MastershipStore {
 
 
     @Override
     @Override
     public NodeId getMaster(DeviceId deviceId) {
     public NodeId getMaster(DeviceId deviceId) {
-        return deserialize(rawMasters.get(serialize(deviceId)));
+        return deserialize(masters.get(serialize(deviceId)));
     }
     }
 
 
     @Override
     @Override
     public Set<DeviceId> getDevices(NodeId nodeId) {
     public Set<DeviceId> getDevices(NodeId nodeId) {
         ImmutableSet.Builder<DeviceId> builder = ImmutableSet.builder();
         ImmutableSet.Builder<DeviceId> builder = ImmutableSet.builder();
 
 
-        for (Map.Entry<byte[], byte[]> entry : rawMasters.entrySet()) {
+        for (Map.Entry<byte[], byte[]> entry : masters.entrySet()) {
             if (nodeId.equals(deserialize(entry.getValue()))) {
             if (nodeId.equals(deserialize(entry.getValue()))) {
                 builder.add((DeviceId) deserialize(entry.getKey()));
                 builder.add((DeviceId) deserialize(entry.getKey()));
             }
             }
@@ -134,11 +158,8 @@ implements MastershipStore {
 
 
     @Override
     @Override
     public MastershipRole requestRole(DeviceId deviceId) {
     public MastershipRole requestRole(DeviceId deviceId) {
-        // first to empty slot for device in master map is MASTER
-        // depending on how backups are organized, might need to trigger election
-        // so only controller doesn't set itself to backup for another device
-        byte [] did = serialize(deviceId);
         NodeId local = clusterService.getLocalNode().id();
         NodeId local = clusterService.getLocalNode().id();
+        byte [] did = serialize(deviceId);
         byte [] lnid = serialize(local);
         byte [] lnid = serialize(local);
 
 
         ILock lock = theInstance.getLock(LOCK);
         ILock lock = theInstance.getLock(LOCK);
@@ -147,15 +168,17 @@ implements MastershipStore {
             MastershipRole role = getRole(local, deviceId);
             MastershipRole role = getRole(local, deviceId);
             switch (role) {
             switch (role) {
                 case MASTER:
                 case MASTER:
+                    evict(lnid, did);
                     break;
                     break;
                 case STANDBY:
                 case STANDBY:
-                    backups.put(lnid, NIL);
-                    rawTerms.putIfAbsent(did, INIT);
+                    backup(lnid, did);
+                    terms.putIfAbsent(did, INIT);
                     break;
                     break;
                 case NONE:
                 case NONE:
-                    rawMasters.put(did, lnid);
-                    rawTerms.putIfAbsent(did, INIT);
-                    backups.put(lnid, NIL);
+                    //claim mastership
+                    masters.put(did, lnid);
+                    evict(lnid, did);
+                    updateTerm(did);
                     role = MastershipRole.MASTER;
                     role = MastershipRole.MASTER;
                     break;
                     break;
                 default:
                 default:
@@ -168,41 +191,50 @@ implements MastershipStore {
     }
     }
 
 
     @Override
     @Override
-    public MastershipRole getRole(NodeId nodeId, DeviceId deviceId) {
+    public MastershipTerm getTermFor(DeviceId deviceId) {
         byte[] did = serialize(deviceId);
         byte[] did = serialize(deviceId);
-
-        NodeId current = deserialize(rawMasters.get(did));
-        MastershipRole role = null;
-
-        if (current == null) {
-            //IFF no controllers have claimed mastership over it
-            role = MastershipRole.NONE;
-        } else {
-            if (current.equals(nodeId)) {
-                role = MastershipRole.MASTER;
-            } else {
-                role = MastershipRole.STANDBY;
-            }
+        if ((masters.get(did) == null) ||
+                (terms.get(did) == null)) {
+            return null;
         }
         }
-
-        return role;
+        return MastershipTerm.of(
+                (NodeId) deserialize(masters.get(did)), terms.get(did));
     }
     }
 
 
     @Override
     @Override
-    public MastershipTerm getTermFor(DeviceId deviceId) {
-        byte[] did = serialize(deviceId);
+    public MastershipEvent setStandby(NodeId nodeId, DeviceId deviceId) {
+        byte [] did = serialize(deviceId);
+        byte [] nid = serialize(nodeId);
+        MastershipEvent event = null;
 
 
-        if ((rawMasters.get(did) == null) ||
-                (rawTerms.get(did) == null)) {
-            return null;
+        ILock lock = theInstance.getLock(LOCK);
+        lock.lock();
+        try {
+            MastershipRole role = getRole(nodeId, deviceId);
+            switch (role) {
+                case MASTER:
+                    event = reelect(nodeId, deviceId);
+                    backup(nid, did);
+                    break;
+                case STANDBY:
+                    //fall through to reinforce role
+                case NONE:
+                    backup(nid, did);
+                    break;
+                default:
+                    log.warn("unknown Mastership Role {}", role);
+            }
+            return event;
+        } finally {
+            lock.unlock();
         }
         }
-        return MastershipTerm.of(
-                (NodeId) deserialize(rawMasters.get(did)), rawTerms.get(did));
     }
     }
 
 
     @Override
     @Override
-    public MastershipEvent unsetMaster(NodeId nodeId, DeviceId deviceId) {
+    public MastershipEvent relinquishRole(NodeId nodeId, DeviceId deviceId) {
         byte [] did = serialize(deviceId);
         byte [] did = serialize(deviceId);
+        byte [] nid = serialize(nodeId);
+        MastershipEvent event = null;
 
 
         ILock lock = theInstance.getLock(LOCK);
         ILock lock = theInstance.getLock(LOCK);
         lock.lock();
         lock.lock();
@@ -210,54 +242,84 @@ implements MastershipStore {
             MastershipRole role = getRole(nodeId, deviceId);
             MastershipRole role = getRole(nodeId, deviceId);
             switch (role) {
             switch (role) {
                 case MASTER:
                 case MASTER:
-                    //hand off device to another
-                    NodeId backup = reelect(nodeId, deviceId);
-                    if (backup == null) {
-                        //goes back to NONE
-                        rawMasters.remove(did);
-                    } else {
-                        //goes to STANDBY for local, MASTER for someone else
-                        Integer term = rawTerms.get(did);
-                        rawMasters.put(did, serialize(backup));
-                        rawTerms.put(did, ++term);
-                        return new MastershipEvent(MASTER_CHANGED, deviceId, backup);
-                    }
+                    event = reelect(nodeId, deviceId);
+                    evict(nid, did);
+                    break;
                 case STANDBY:
                 case STANDBY:
+                    //fall through to reinforce relinquishment
                 case NONE:
                 case NONE:
+                    evict(nid, did);
                     break;
                     break;
                 default:
                 default:
                 log.warn("unknown Mastership Role {}", role);
                 log.warn("unknown Mastership Role {}", role);
             }
             }
-            return null;
+            return event;
         } finally {
         } finally {
             lock.unlock();
             lock.unlock();
         }
         }
     }
     }
 
 
-    //helper for "re-electing" a new master for a given device
-    private NodeId reelect(NodeId current, DeviceId deviceId) {
+    //helper to fetch a new master candidate for a given device.
+    private MastershipEvent reelect(NodeId current, DeviceId deviceId) {
+        byte [] did = serialize(deviceId);
+        byte [] nid = serialize(current);
 
 
-        for (byte [] node : backups.keySet()) {
-            NodeId nid = deserialize(node);
-            //if a device dies we shouldn't pick another master for it.
-            if (!current.equals(nid) && (deviceService.isAvailable(deviceId))) {
-                return nid;
+        //if this is an queue it'd be neater.
+        byte [] backup = null;
+        for (byte [] n : standbys.get(serialize(deviceId))) {
+            if (!current.equals(deserialize(n))) {
+                backup = n;
+                break;
             }
             }
         }
         }
+
+        if (backup == null) {
+            masters.remove(did, nid);
             return null;
             return null;
+        } else {
+            masters.put(did, backup);
+            evict(backup, did);
+            Integer term = terms.get(did);
+            terms.put(did, ++term);
+            return new MastershipEvent(
+                    MASTER_CHANGED, deviceId, (NodeId) deserialize(backup));
+        }
     }
     }
 
 
-    //adds node to pool(s) of backup
-    private void backup(NodeId nodeId, DeviceId deviceId) {
-        //TODO might be useful to isolate out this function and reelect() if we
-        //get more backup/election schemes
+    //adds node to pool(s) of backups and moves them from unusable.
+    private void backup(byte [] nodeId, byte [] deviceId) {
+        if (!standbys.containsEntry(deviceId, nodeId)) {
+            standbys.put(deviceId, nodeId);
+        }
+        if (unusable.containsEntry(deviceId, nodeId)) {
+            unusable.remove(deviceId, nodeId);
+        }
+    }
+
+    //adds node to unusable and evicts it from backup pool.
+    private void evict(byte [] nodeId, byte [] deviceId) {
+        if (!unusable.containsEntry(deviceId, nodeId)) {
+            unusable.put(deviceId, nodeId);
+        }
+        if (standbys.containsEntry(deviceId, nodeId)) {
+            standbys.remove(deviceId, nodeId);
+        }
+    }
+
+    //adds or updates term information.
+    private void updateTerm(byte [] deviceId) {
+        Integer term = terms.get(deviceId);
+        if (term == null) {
+            terms.put(deviceId, INIT);
+        } else {
+            terms.put(deviceId, ++term);
+        }
     }
     }
 
 
     private class RemoteMasterShipEventHandler extends RemoteEventHandler<DeviceId, NodeId> {
     private class RemoteMasterShipEventHandler extends RemoteEventHandler<DeviceId, NodeId> {
 
 
         @Override
         @Override
         protected void onAdd(DeviceId deviceId, NodeId nodeId) {
         protected void onAdd(DeviceId deviceId, NodeId nodeId) {
-            //only addition indicates a change in mastership
             notifyDelegate(new MastershipEvent(MASTER_CHANGED, deviceId, nodeId));
             notifyDelegate(new MastershipEvent(MASTER_CHANGED, deviceId, nodeId));
         }
         }
 
 
@@ -268,6 +330,7 @@ implements MastershipStore {
 
 
         @Override
         @Override
         protected void onUpdate(DeviceId deviceId, NodeId oldNodeId, NodeId nodeId) {
         protected void onUpdate(DeviceId deviceId, NodeId oldNodeId, NodeId nodeId) {
+            //only addition indicates a change in mastership
             //notifyDelegate(new MastershipEvent(MASTER_CHANGED, deviceId, nodeId));
             //notifyDelegate(new MastershipEvent(MASTER_CHANGED, deviceId, nodeId));
         }
         }
     }
     }

@@ -5,7 +5,7 @@ import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.assertTrue;
 import static org.onlab.onos.net.MastershipRole.*;
 import static org.onlab.onos.net.MastershipRole.*;
 
 
-import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.Set;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeUnit;
@@ -26,13 +26,7 @@ import org.onlab.onos.cluster.MastershipEvent.Type;
 import org.onlab.onos.cluster.MastershipStoreDelegate;
 import org.onlab.onos.cluster.MastershipStoreDelegate;
 import org.onlab.onos.cluster.MastershipTerm;
 import org.onlab.onos.cluster.MastershipTerm;
 import org.onlab.onos.cluster.NodeId;
 import org.onlab.onos.cluster.NodeId;
-import org.onlab.onos.net.Device;
 import org.onlab.onos.net.DeviceId;
 import org.onlab.onos.net.DeviceId;
-import org.onlab.onos.net.MastershipRole;
-import org.onlab.onos.net.Port;
-import org.onlab.onos.net.PortNumber;
-import org.onlab.onos.net.device.DeviceListener;
-import org.onlab.onos.net.device.DeviceService;
 import org.onlab.onos.store.common.StoreManager;
 import org.onlab.onos.store.common.StoreManager;
 import org.onlab.onos.store.common.StoreService;
 import org.onlab.onos.store.common.StoreService;
 import org.onlab.onos.store.common.TestStoreManager;
 import org.onlab.onos.store.common.TestStoreManager;
@@ -87,7 +81,6 @@ public class DistributedMastershipStoreTest {
 
 
         dms = new TestDistributedMastershipStore(storeMgr, serializationMgr);
         dms = new TestDistributedMastershipStore(storeMgr, serializationMgr);
         dms.clusterService = new TestClusterService();
         dms.clusterService = new TestClusterService();
-        dms.deviceService = new TestDeviceService();
         dms.activate();
         dms.activate();
 
 
         testStore = (TestDistributedMastershipStore) dms;
         testStore = (TestDistributedMastershipStore) dms;
@@ -105,14 +98,14 @@ public class DistributedMastershipStoreTest {
     @Test
     @Test
     public void getRole() {
     public void getRole() {
         assertEquals("wrong role:", NONE, dms.getRole(N1, DID1));
         assertEquals("wrong role:", NONE, dms.getRole(N1, DID1));
-        testStore.put(DID1, N1, true, true, true);
+        testStore.put(DID1, N1, true, false, true);
         assertEquals("wrong role:", MASTER, dms.getRole(N1, DID1));
         assertEquals("wrong role:", MASTER, dms.getRole(N1, DID1));
         assertEquals("wrong role:", STANDBY, dms.getRole(N2, DID1));
         assertEquals("wrong role:", STANDBY, dms.getRole(N2, DID1));
     }
     }
 
 
     @Test
     @Test
     public void getMaster() {
     public void getMaster() {
-        assertTrue("wrong store state:", dms.rawMasters.isEmpty());
+        assertTrue("wrong store state:", dms.masters.isEmpty());
 
 
         testStore.put(DID1, N1, true, false, false);
         testStore.put(DID1, N1, true, false, false);
         assertEquals("wrong master:", N1, dms.getMaster(DID1));
         assertEquals("wrong master:", N1, dms.getMaster(DID1));
@@ -121,7 +114,7 @@ public class DistributedMastershipStoreTest {
 
 
     @Test
     @Test
     public void getDevices() {
     public void getDevices() {
-        assertTrue("wrong store state:", dms.rawMasters.isEmpty());
+        assertTrue("wrong store state:", dms.masters.isEmpty());
 
 
         testStore.put(DID1, N1, true, false, false);
         testStore.put(DID1, N1, true, false, false);
         testStore.put(DID2, N1, true, false, false);
         testStore.put(DID2, N1, true, false, false);
@@ -139,20 +132,17 @@ public class DistributedMastershipStoreTest {
         //if already MASTER, nothing should happen
         //if already MASTER, nothing should happen
         testStore.put(DID2, N1, true, false, false);
         testStore.put(DID2, N1, true, false, false);
         assertEquals("wrong role for MASTER:", MASTER, dms.requestRole(DID2));
         assertEquals("wrong role for MASTER:", MASTER, dms.requestRole(DID2));
-        assertTrue("wrong state for store:",
-                dms.backups.isEmpty() & dms.rawTerms.isEmpty());
 
 
         //populate maps with DID1, N1 thru NONE case
         //populate maps with DID1, N1 thru NONE case
         assertEquals("wrong role for NONE:", MASTER, dms.requestRole(DID1));
         assertEquals("wrong role for NONE:", MASTER, dms.requestRole(DID1));
-        assertTrue("wrong state for store:",
-                !dms.backups.isEmpty() & !dms.rawTerms.isEmpty());
+        assertTrue("wrong state for store:", !dms.terms.isEmpty());
         assertEquals("wrong term",
         assertEquals("wrong term",
                 MastershipTerm.of(N1, 0), dms.getTermFor(DID1));
                 MastershipTerm.of(N1, 0), dms.getTermFor(DID1));
 
 
         //CN2 now local. DID2 has N1 as MASTER so N2 is STANDBY
         //CN2 now local. DID2 has N1 as MASTER so N2 is STANDBY
         testStore.setCurrent(CN2);
         testStore.setCurrent(CN2);
         assertEquals("wrong role for STANDBY:", STANDBY, dms.requestRole(DID2));
         assertEquals("wrong role for STANDBY:", STANDBY, dms.requestRole(DID2));
-        assertEquals("wrong number of entries:", 2, dms.rawTerms.size());
+        assertEquals("wrong number of entries:", 2, dms.terms.size());
 
 
         //change term and requestRole() again; should persist
         //change term and requestRole() again; should persist
         testStore.increment(DID2);
         testStore.increment(DID2);
@@ -181,35 +171,42 @@ public class DistributedMastershipStoreTest {
     }
     }
 
 
     @Test
     @Test
-    public void unsetMaster() {
+    public void relinquishRole() {
         //populate maps with DID1, N1 as MASTER thru NONE case
         //populate maps with DID1, N1 as MASTER thru NONE case
         testStore.setCurrent(CN1);
         testStore.setCurrent(CN1);
         assertEquals("wrong role for NONE:", MASTER, dms.requestRole(DID1));
         assertEquals("wrong role for NONE:", MASTER, dms.requestRole(DID1));
         //no backup, no new MASTER/event
         //no backup, no new MASTER/event
-        assertNull("wrong event:", dms.unsetMaster(N1, DID1));
+        assertNull("wrong event:", dms.relinquishRole(N1, DID1));
 
 
         dms.requestRole(DID1);
         dms.requestRole(DID1);
-        ((TestDeviceService) dms.deviceService).active.add(DID1);
 
 
         //add backup CN2, get it elected MASTER by relinquishing
         //add backup CN2, get it elected MASTER by relinquishing
         testStore.setCurrent(CN2);
         testStore.setCurrent(CN2);
-        dms.requestRole(DID1);
-        assertEquals("wrong event:", Type.MASTER_CHANGED, dms.unsetMaster(N1, DID1).type());
+        assertEquals("wrong role for NONE:", STANDBY, dms.requestRole(DID1));
+        assertEquals("wrong event:", Type.MASTER_CHANGED, dms.relinquishRole(N1, DID1).type());
         assertEquals("wrong master", N2, dms.getMaster(DID1));
         assertEquals("wrong master", N2, dms.getMaster(DID1));
 
 
         //STANDBY - nothing here, either
         //STANDBY - nothing here, either
-        assertNull("wrong event:", dms.unsetMaster(N1, DID1));
+        assertNull("wrong event:", dms.relinquishRole(N1, DID1));
         assertEquals("wrong role for node:", STANDBY, dms.getRole(N1, DID1));
         assertEquals("wrong role for node:", STANDBY, dms.getRole(N1, DID1));
 
 
+        //all nodes "give up" on device, which goes back to NONE.
+        assertNull("wrong event:", dms.relinquishRole(N2, DID1));
+        assertEquals("wrong role for node:", NONE, dms.getRole(N2, DID1));
+        assertEquals("wrong role for node:", NONE, dms.getRole(N1, DID1));
+
+        assertEquals("wrong number of retired nodes", 2, dms.unusable.size());
+
+        //bring nodes back
+        assertEquals("wrong role for NONE:", MASTER, dms.requestRole(DID1));
+        testStore.setCurrent(CN1);
+        assertEquals("wrong role for NONE:", STANDBY, dms.requestRole(DID1));
+        assertEquals("wrong number of backup nodes", 1, dms.standbys.size());
+
         //NONE - nothing happens
         //NONE - nothing happens
-        assertNull("wrong event:", dms.unsetMaster(N1, DID2));
+        assertNull("wrong event:", dms.relinquishRole(N1, DID2));
         assertEquals("wrong role for node:", NONE, dms.getRole(N1, DID2));
         assertEquals("wrong role for node:", NONE, dms.getRole(N1, DID2));
 
 
-        //for a device that turned off (not active) - status to NONE
-        ((TestDeviceService) dms.deviceService).active.clear();
-        assertNull("extraneous event:", dms.unsetMaster(N2, DID1));
-        assertEquals("wrong role", NONE, dms.getRole(N2, DID1));
-
     }
     }
 
 
     @Ignore("Ignore until Delegate spec. is clear.")
     @Ignore("Ignore until Delegate spec. is clear.")
@@ -244,36 +241,55 @@ public class DistributedMastershipStoreTest {
 
 
         //helper to populate master/backup structures
         //helper to populate master/backup structures
         public void put(DeviceId dev, NodeId node,
         public void put(DeviceId dev, NodeId node,
-                boolean store, boolean backup, boolean term) {
-            if (store) {
-                dms.rawMasters.put(serialize(dev), serialize(node));
+                boolean master, boolean backup, boolean term) {
+            byte [] n = serialize(node);
+            byte [] d = serialize(dev);
+
+            if (master) {
+                dms.masters.put(d, n);
+                dms.unusable.put(d, n);
+                dms.standbys.remove(d, n);
             }
             }
             if (backup) {
             if (backup) {
-                dms.backups.put(serialize(node), (byte) 0);
+                dms.standbys.put(d, n);
+                dms.masters.remove(d, n);
+                dms.unusable.remove(d, n);
             }
             }
             if (term) {
             if (term) {
-                dms.rawTerms.put(serialize(dev), 0);
+                dms.terms.put(d, 0);
+            }
+        }
+
+        public void dump() {
+            System.out.println("standbys");
+            for (Map.Entry<byte [], byte []> e : standbys.entrySet()) {
+                System.out.println(deserialize(e.getKey()) + ":" + deserialize(e.getValue()));
+            }
+            System.out.println("unusable");
+            for (Map.Entry<byte [], byte []> e : unusable.entrySet()) {
+                System.out.println(deserialize(e.getKey()) + ":" + deserialize(e.getValue()));
             }
             }
         }
         }
 
 
         //clears structures
         //clears structures
         public void reset(boolean store, boolean backup, boolean term) {
         public void reset(boolean store, boolean backup, boolean term) {
             if (store) {
             if (store) {
-                dms.rawMasters.clear();
+                dms.masters.clear();
+                dms.unusable.clear();
             }
             }
             if (backup) {
             if (backup) {
-                dms.backups.clear();
+                dms.standbys.clear();
             }
             }
             if (term) {
             if (term) {
-                dms.rawTerms.clear();
+                dms.terms.clear();
             }
             }
         }
         }
 
 
         //increment term for a device
         //increment term for a device
         public void increment(DeviceId dev) {
         public void increment(DeviceId dev) {
-            Integer t = dms.rawTerms.get(serialize(dev));
+            Integer t = dms.terms.get(serialize(dev));
             if (t != null) {
             if (t != null) {
-                dms.rawTerms.put(serialize(dev), ++t);
+                dms.terms.put(serialize(dev), ++t);
             }
             }
         }
         }
 
 
@@ -317,52 +333,4 @@ public class DistributedMastershipStoreTest {
 
 
     }
     }
 
 
-    private class TestDeviceService implements DeviceService {
-
-        Set<DeviceId> active = Sets.newHashSet();
-
-        @Override
-        public int getDeviceCount() {
-            return 0;
-        }
-
-        @Override
-        public Iterable<Device> getDevices() {
-            return null;
-        }
-
-        @Override
-        public Device getDevice(DeviceId deviceId) {
-            return null;
-        }
-
-        @Override
-        public MastershipRole getRole(DeviceId deviceId) {
-            return null;
-        }
-
-        @Override
-        public List<Port> getPorts(DeviceId deviceId) {
-            return null;
-        }
-
-        @Override
-        public Port getPort(DeviceId deviceId, PortNumber portNumber) {
-            return null;
-        }
-
-        @Override
-        public boolean isAvailable(DeviceId deviceId) {
-            return active.contains(deviceId);
-        }
-
-        @Override
-        public void addListener(DeviceListener listener) {
-        }
-
-        @Override
-        public void removeListener(DeviceListener listener) {
-        }
-
-    }
 }
 }

@@ -174,7 +174,7 @@ public class SimpleMastershipStore
     }
     }
 
 
     @Override
     @Override
-    public MastershipEvent unsetMaster(NodeId nodeId, DeviceId deviceId) {
+    public MastershipEvent setStandby(NodeId nodeId, DeviceId deviceId) {
         MastershipRole role = getRole(nodeId, deviceId);
         MastershipRole role = getRole(nodeId, deviceId);
         synchronized (this) {
         synchronized (this) {
             switch (role) {
             switch (role) {
@@ -214,4 +214,9 @@ public class SimpleMastershipStore
         return backup;
         return backup;
     }
     }
 
 
+    @Override
+    public MastershipEvent relinquishRole(NodeId nodeId, DeviceId deviceId) {
+        return setStandby(nodeId, deviceId);
+    }
+
 }
 }

@@ -129,22 +129,22 @@ public class SimpleMastershipStoreTest {
     public void unsetMaster() {
     public void unsetMaster() {
         //NONE - record backup but take no other action
         //NONE - record backup but take no other action
         put(DID1, N1, false, false);
         put(DID1, N1, false, false);
-        sms.unsetMaster(N1, DID1);
+        sms.setStandby(N1, DID1);
         assertTrue("not backed up", sms.backups.contains(N1));
         assertTrue("not backed up", sms.backups.contains(N1));
         sms.termMap.clear();
         sms.termMap.clear();
-        sms.unsetMaster(N1, DID1);
+        sms.setStandby(N1, DID1);
         assertTrue("term not set", sms.termMap.containsKey(DID1));
         assertTrue("term not set", sms.termMap.containsKey(DID1));
 
 
         //no backup, MASTER
         //no backup, MASTER
         put(DID1, N1, true, true);
         put(DID1, N1, true, true);
-        assertNull("wrong event", sms.unsetMaster(N1, DID1));
+        assertNull("wrong event", sms.setStandby(N1, DID1));
         assertNull("wrong node", sms.masterMap.get(DID1));
         assertNull("wrong node", sms.masterMap.get(DID1));
 
 
         //backup, switch
         //backup, switch
         sms.masterMap.clear();
         sms.masterMap.clear();
         put(DID1, N1, true, true);
         put(DID1, N1, true, true);
         put(DID2, N2, true, true);
         put(DID2, N2, true, true);
-        assertEquals("wrong event", MASTER_CHANGED, sms.unsetMaster(N1, DID1).type());
+        assertEquals("wrong event", MASTER_CHANGED, sms.setStandby(N1, DID1).type());
     }
     }
 
 
     //helper to populate master/backup structures
     //helper to populate master/backup structures

@@ -981,11 +981,13 @@ class OFChannelHandler extends IdleStateAwareChannelHandler {
                 // switch was a duplicate-dpid, calling the method below would clear
                 // switch was a duplicate-dpid, calling the method below would clear
                 // all state for the original switch (with the same dpid),
                 // all state for the original switch (with the same dpid),
                 // which we obviously don't want.
                 // which we obviously don't want.
+                log.info("{}:removal called");
                 sw.removeConnectedSwitch();
                 sw.removeConnectedSwitch();
             } else {
             } else {
                 // A duplicate was disconnected on this ChannelHandler,
                 // A duplicate was disconnected on this ChannelHandler,
                 // this is the same switch reconnecting, but the original state was
                 // this is the same switch reconnecting, but the original state was
                 // not cleaned up - XXX check liveness of original ChannelHandler
                 // not cleaned up - XXX check liveness of original ChannelHandler
+                log.info("{}:duplicate found");
                 duplicateDpidFound = Boolean.FALSE;
                 duplicateDpidFound = Boolean.FALSE;
             }
             }
         } else {
         } else {

@@ -307,9 +307,11 @@ public class OpenFlowControllerImpl implements OpenFlowController {
             connectedSwitches.remove(dpid);
             connectedSwitches.remove(dpid);
             OpenFlowSwitch sw = activeMasterSwitches.remove(dpid);
             OpenFlowSwitch sw = activeMasterSwitches.remove(dpid);
             if (sw == null) {
             if (sw == null) {
+                log.warn("sw was null for {}", dpid);
                 sw = activeEqualSwitches.remove(dpid);
                 sw = activeEqualSwitches.remove(dpid);
             }
             }
             for (OpenFlowSwitchListener l : ofSwitchListener) {
             for (OpenFlowSwitchListener l : ofSwitchListener) {
+                log.warn("removal for {}", dpid);
                 l.switchRemoved(dpid);
                 l.switchRemoved(dpid);
             }
             }
         }
         }