opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/entityownership/EntityOwnershipShard.java

   1 /*
   2  * Copyright (c) 2015 Brocade Communications Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.controller.cluster.datastore.entityownership;
   9
  10 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.CANDIDATE_NAME_NODE_ID;
  11 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.CANDIDATE_NODE_ID;
  12 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_ID_NODE_ID;
  13 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_ID_QNAME;
  14 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_NODE_ID;
  15 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_OWNERS_PATH;
  16 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_OWNER_NODE_ID;
  17 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_OWNER_QNAME;
  18 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_TYPES_PATH;
  19 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_TYPE_NODE_ID;
  20 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_TYPE_QNAME;
  21 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.candidateMapEntry;
  22 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.candidateNodeKey;
  23 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.candidatePath;
  24 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.createEntity;
  25 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.entityOwnersWithCandidate;
  26 import akka.actor.ActorRef;
  27 import akka.actor.ActorSelection;
  28 import akka.pattern.Patterns;
  29 import com.google.common.base.Optional;
  30 import com.google.common.base.Preconditions;
  31 import com.google.common.base.Strings;
  32 import java.util.ArrayList;
  33 import java.util.Collection;
  34 import java.util.HashMap;
  35 import java.util.HashSet;
  36 import java.util.Map;
  37 import java.util.Set;
  38 import java.util.concurrent.TimeUnit;
  39 import org.opendaylight.controller.cluster.datastore.DatastoreContext;
  40 import org.opendaylight.controller.cluster.datastore.Shard;
  41 import org.opendaylight.controller.cluster.datastore.entityownership.messages.CandidateAdded;
  42 import org.opendaylight.controller.cluster.datastore.entityownership.messages.CandidateRemoved;
  43 import org.opendaylight.controller.cluster.datastore.entityownership.messages.RegisterCandidateLocal;
  44 import org.opendaylight.controller.cluster.datastore.entityownership.messages.RegisterListenerLocal;
  45 import org.opendaylight.controller.cluster.datastore.entityownership.messages.UnregisterCandidateLocal;
  46 import org.opendaylight.controller.cluster.datastore.entityownership.messages.UnregisterListenerLocal;
  47 import org.opendaylight.controller.cluster.datastore.entityownership.selectionstrategy.EntityOwnerSelectionStrategy;
  48 import org.opendaylight.controller.cluster.datastore.entityownership.selectionstrategy.FirstCandidateSelectionStrategy;
  49 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  50 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  51 import org.opendaylight.controller.cluster.datastore.messages.PeerDown;
  52 import org.opendaylight.controller.cluster.datastore.messages.PeerUp;
  53 import org.opendaylight.controller.cluster.datastore.messages.SuccessReply;
  54 import org.opendaylight.controller.cluster.datastore.modification.DeleteModification;
  55 import org.opendaylight.controller.cluster.datastore.modification.MergeModification;
  56 import org.opendaylight.controller.cluster.datastore.modification.WriteModification;
  57 import org.opendaylight.controller.md.sal.common.api.clustering.Entity;
  58 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  59 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
  60 import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
  61 import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
  62 import org.opendaylight.yangtools.yang.data.api.schema.MapNode;
  63 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  64 import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNodes;
  65 import scala.concurrent.Future;
  66
  67 /**
  68  * Special Shard for EntityOwnership.
  69  *
  70  * @author Thomas Pantelis
  71  */
  72 class EntityOwnershipShard extends Shard {
  73
  74     private static final EntityOwnerSelectionStrategy DEFAULT_ENTITY_OWNER_SELECTION_STRATEGY
  75             = FirstCandidateSelectionStrategy.INSTANCE;
  76
  77     private final String localMemberName;
  78     private final EntityOwnershipShardCommitCoordinator commitCoordinator;
  79     private final EntityOwnershipListenerSupport listenerSupport;
  80     private final Set<String> downPeerMemberNames = new HashSet<>();
  81     private final Map<String, String> peerIdToMemberNames = new HashMap<>();
  82     private final Map<String, EntityOwnerSelectionStrategy> ownerSelectionStrategies = new HashMap<>();
  83
  84     private static DatastoreContext noPersistenceDatastoreContext(DatastoreContext datastoreContext) {
  85         return DatastoreContext.newBuilderFrom(datastoreContext).persistent(false).build();
  86     }
  87
  88     protected EntityOwnershipShard(Builder builder) {
  89         super(builder);
  90         this.localMemberName = builder.localMemberName;
  91         this.commitCoordinator = new EntityOwnershipShardCommitCoordinator(builder.localMemberName, LOG);
  92         this.listenerSupport = new EntityOwnershipListenerSupport(getContext(), persistenceId());
  93
  94         for(String peerId: getRaftActorContext().getPeerIds()) {
  95             ShardIdentifier shardId = ShardIdentifier.builder().fromShardIdString(peerId).build();
  96             peerIdToMemberNames.put(peerId, shardId.getMemberName());
  97         }
  98     }
  99
 100     @Override
 101     protected void onDatastoreContext(DatastoreContext context) {
 102         super.onDatastoreContext(noPersistenceDatastoreContext(context));
 103     }
 104
 105     @Override
 106     protected void onRecoveryComplete() {
 107         super.onRecoveryComplete();
 108
 109         new CandidateListChangeListener(getSelf(), persistenceId()).init(getDataStore());
 110         new EntityOwnerChangeListener(localMemberName, listenerSupport).init(getDataStore());
 111     }
 112
 113     @Override
 114     public void onReceiveCommand(final Object message) throws Exception {
 115         if(message instanceof RegisterCandidateLocal) {
 116             onRegisterCandidateLocal((RegisterCandidateLocal)message);
 117         } else if(message instanceof UnregisterCandidateLocal) {
 118             onUnregisterCandidateLocal((UnregisterCandidateLocal)message);
 119         } else if(message instanceof CandidateAdded){
 120             onCandidateAdded((CandidateAdded) message);
 121         } else if(message instanceof CandidateRemoved){
 122             onCandidateRemoved((CandidateRemoved) message);
 123         } else if(message instanceof PeerDown) {
 124             onPeerDown((PeerDown) message);
 125         } else if(message instanceof PeerUp) {
 126             onPeerUp((PeerUp) message);
 127         } if(message instanceof RegisterListenerLocal) {
 128             onRegisterListenerLocal((RegisterListenerLocal)message);
 129         } if(message instanceof UnregisterListenerLocal) {
 130             onUnregisterListenerLocal((UnregisterListenerLocal)message);
 131         } else if(!commitCoordinator.handleMessage(message, this)) {
 132             super.onReceiveCommand(message);
 133         }
 134     }
 135
 136     private void onRegisterCandidateLocal(RegisterCandidateLocal registerCandidate) {
 137         LOG.debug("{}: onRegisterCandidateLocal: {}", persistenceId(), registerCandidate);
 138
 139         listenerSupport.setHasCandidateForEntity(registerCandidate.getEntity());
 140
 141         NormalizedNode<?, ?> entityOwners = entityOwnersWithCandidate(registerCandidate.getEntity().getType(),
 142                 registerCandidate.getEntity().getId(), localMemberName);
 143         commitCoordinator.commitModification(new MergeModification(ENTITY_OWNERS_PATH, entityOwners), this);
 144
 145         getSender().tell(SuccessReply.INSTANCE, getSelf());
 146     }
 147
 148     private void onUnregisterCandidateLocal(UnregisterCandidateLocal unregisterCandidate) {
 149         LOG.debug("{}: onUnregisterCandidateLocal: {}", persistenceId(), unregisterCandidate);
 150
 151         Entity entity = unregisterCandidate.getEntity();
 152         listenerSupport.unsetHasCandidateForEntity(entity);
 153
 154         YangInstanceIdentifier candidatePath = candidatePath(entity.getType(), entity.getId(), localMemberName);
 155         commitCoordinator.commitModification(new DeleteModification(candidatePath), this);
 156
 157         getSender().tell(SuccessReply.INSTANCE, getSelf());
 158     }
 159
 160     private void onRegisterListenerLocal(final RegisterListenerLocal registerListener) {
 161         LOG.debug("{}: onRegisterListenerLocal: {}", persistenceId(), registerListener);
 162
 163         listenerSupport.addEntityOwnershipListener(registerListener.getEntityType(), registerListener.getListener());
 164
 165         getSender().tell(SuccessReply.INSTANCE, getSelf());
 166
 167         searchForEntitiesOwnedBy(localMemberName, new EntityWalker() {
 168             @Override
 169             public void onEntity(MapEntryNode entityTypeNode, MapEntryNode entityNode) {
 170                 Optional<DataContainerChild<? extends PathArgument, ?>> possibleType =
 171                         entityTypeNode.getChild(ENTITY_TYPE_NODE_ID);
 172                 String entityType = possibleType.isPresent() ? possibleType.get().getValue().toString() : null;
 173                 if (registerListener.getEntityType().equals(entityType)) {
 174                     Entity entity = new Entity(entityType,
 175                             (YangInstanceIdentifier) entityNode.getChild(ENTITY_ID_NODE_ID).get().getValue());
 176                     listenerSupport.notifyEntityOwnershipListener(entity, false, true, true, registerListener.getListener());
 177                 }
 178             }
 179         });
 180     }
 181
 182     private void onUnregisterListenerLocal(UnregisterListenerLocal unregisterListener) {
 183         LOG.debug("{}: onUnregisterListenerLocal: {}", persistenceId(), unregisterListener);
 184
 185         listenerSupport.removeEntityOwnershipListener(unregisterListener.getEntityType(), unregisterListener.getListener());
 186
 187         getSender().tell(SuccessReply.INSTANCE, getSelf());
 188     }
 189
 190     void tryCommitModifications(final BatchedModifications modifications) {
 191         if(isLeader()) {
 192             LOG.debug("{}: Committing BatchedModifications {} locally", persistenceId(), modifications.getTransactionID());
 193
 194             // Note that it's possible the commit won't get consensus and will timeout and not be applied
 195             // to the state. However we don't need to retry it in that case b/c it will be committed to
 196             // the journal first and, once a majority of followers come back on line and it is replicated,
 197             // it will be applied at that point.
 198             handleBatchedModificationsLocal(modifications, self());
 199         } else {
 200             final ActorSelection leader = getLeader();
 201             if (leader != null) {
 202                 if(LOG.isDebugEnabled()) {
 203                     LOG.debug("{}: Sending BatchedModifications {} to leader {}", persistenceId(),
 204                             modifications.getTransactionID(), leader);
 205                 }
 206
 207                 Future<Object> future = Patterns.ask(leader, modifications, TimeUnit.SECONDS.toMillis(
 208                         getDatastoreContext().getShardTransactionCommitTimeoutInSeconds()));
 209
 210                 Patterns.pipe(future, getContext().dispatcher()).pipeTo(getSelf(), ActorRef.noSender());
 211             }
 212         }
 213     }
 214
 215     boolean hasLeader() {
 216         return getLeader() != null && !isIsolatedLeader();
 217     }
 218
 219     @Override
 220     protected void onStateChanged() {
 221         super.onStateChanged();
 222
 223         commitCoordinator.onStateChanged(this, isLeader());
 224     }
 225
 226     @Override
 227     protected void onLeaderChanged(String oldLeader, String newLeader) {
 228         super.onLeaderChanged(oldLeader, newLeader);
 229
 230         LOG.debug("{}: onLeaderChanged: oldLeader: {}, newLeader: {}, isLeader: {}", persistenceId(), oldLeader,
 231                 newLeader, isLeader());
 232
 233         if(isLeader()) {
 234             // We were just elected leader. If the old leader is down, select new owners for the entities
 235             // owned by the down leader.
 236
 237             String oldLeaderMemberName = peerIdToMemberNames.get(oldLeader);
 238
 239             LOG.debug("{}: oldLeaderMemberName: {}", persistenceId(), oldLeaderMemberName);
 240
 241             if(downPeerMemberNames.contains(oldLeaderMemberName)) {
 242                 selectNewOwnerForEntitiesOwnedBy(oldLeaderMemberName);
 243             }
 244         }
 245     }
 246
 247     private void onCandidateRemoved(CandidateRemoved message) {
 248         LOG.debug("{}: onCandidateRemoved: {}", persistenceId(), message);
 249
 250         if(isLeader()) {
 251             String currentOwner = getCurrentOwner(message.getEntityPath());
 252             if(message.getRemovedCandidate().equals(currentOwner)){
 253                 writeNewOwner(message.getEntityPath(), newOwner(message.getRemainingCandidates(),
 254                         getEntityOwnerElectionStrategy(message.getEntityPath())));
 255             }
 256         } else {
 257             // We're not the leader. If the removed candidate is our local member then check if we actually
 258             // have a local candidate registered. If we do then we must have been partitioned from the leader
 259             // and the leader removed our candidate since the leader can't tell the difference between a
 260             // temporary network partition and a node's process actually restarted. So, in that case, re-add
 261             // our candidate.
 262             if(localMemberName.equals(message.getRemovedCandidate()) &&
 263                     listenerSupport.hasCandidateForEntity(createEntity(message.getEntityPath()))) {
 264                 LOG.debug("Local candidate member was removed but a local candidate is registered for {}" +
 265                     " - adding back local candidate", message.getEntityPath());
 266
 267                 commitCoordinator.commitModification(new MergeModification(
 268                         candidatePath(message.getEntityPath(), localMemberName),
 269                         candidateMapEntry(localMemberName)), this);
 270             }
 271         }
 272     }
 273
 274     private EntityOwnerSelectionStrategy getEntityOwnerElectionStrategy(YangInstanceIdentifier entityPath) {
 275         String entityType = EntityOwnersModel.entityTypeFromEntityPath(entityPath);
 276         EntityOwnerSelectionStrategy entityOwnerSelectionStrategy = ownerSelectionStrategies.get(entityType);
 277
 278         if(entityOwnerSelectionStrategy == null){
 279             entityOwnerSelectionStrategy = DEFAULT_ENTITY_OWNER_SELECTION_STRATEGY;
 280             ownerSelectionStrategies.put(entityType, entityOwnerSelectionStrategy);
 281         }
 282
 283         return entityOwnerSelectionStrategy;
 284     }
 285
 286     private void onCandidateAdded(CandidateAdded message) {
 287         if(!isLeader()){
 288             return;
 289         }
 290
 291         LOG.debug("{}: onCandidateAdded: {}", persistenceId(), message);
 292
 293         // Since a node's candidate member is only added by the node itself, we can assume the node is up so
 294         // remove it from the downPeerMemberNames.
 295         downPeerMemberNames.remove(message.getNewCandidate());
 296
 297         String currentOwner = getCurrentOwner(message.getEntityPath());
 298         if(Strings.isNullOrEmpty(currentOwner)){
 299             EntityOwnerSelectionStrategy entityOwnerSelectionStrategy
 300                     = getEntityOwnerElectionStrategy(message.getEntityPath());
 301             if(entityOwnerSelectionStrategy.selectionDelayInMillis() == 0L) {
 302                 writeNewOwner(message.getEntityPath(), newOwner(message.getAllCandidates(),
 303                         entityOwnerSelectionStrategy));
 304             } else {
 305                 throw new UnsupportedOperationException("Delayed selection not implemented yet");
 306             }
 307         }
 308     }
 309
 310     private void onPeerDown(PeerDown peerDown) {
 311         LOG.info("{}: onPeerDown: {}", persistenceId(), peerDown);
 312
 313         String downMemberName = peerDown.getMemberName();
 314         if(downPeerMemberNames.add(downMemberName) && isLeader()) {
 315             // Remove the down peer as a candidate from all entities.
 316             removeCandidateFromEntities(downMemberName);
 317         }
 318     }
 319
 320     private void onPeerUp(PeerUp peerUp) {
 321         LOG.debug("{}: onPeerUp: {}", persistenceId(), peerUp);
 322
 323         peerIdToMemberNames.put(peerUp.getPeerId(), peerUp.getMemberName());
 324         downPeerMemberNames.remove(peerUp.getMemberName());
 325     }
 326
 327     private void selectNewOwnerForEntitiesOwnedBy(String owner) {
 328         final BatchedModifications modifications = commitCoordinator.newBatchedModifications();
 329         searchForEntitiesOwnedBy(owner, new EntityWalker() {
 330             @Override
 331             public void onEntity(MapEntryNode entityTypeNode, MapEntryNode entityNode) {
 332
 333                 YangInstanceIdentifier entityPath = YangInstanceIdentifier.builder(ENTITY_TYPES_PATH).
 334                         node(entityTypeNode.getIdentifier()).node(ENTITY_NODE_ID).node(entityNode.getIdentifier()).
 335                         node(ENTITY_OWNER_NODE_ID).build();
 336
 337                 Object newOwner = newOwner(getCandidateNames(entityNode), getEntityOwnerElectionStrategy(entityPath));
 338
 339                 LOG.debug("{}: Found entity {}, writing new owner {}", persistenceId(), entityPath, newOwner);
 340
 341                 modifications.addModification(new WriteModification(entityPath,
 342                         ImmutableNodes.leafNode(ENTITY_OWNER_NODE_ID, newOwner)));
 343             }
 344         });
 345
 346         commitCoordinator.commitModifications(modifications, this);
 347     }
 348
 349     private void removeCandidateFromEntities(final String owner) {
 350         final BatchedModifications modifications = commitCoordinator.newBatchedModifications();
 351         searchForEntities(new EntityWalker() {
 352             @Override
 353             public void onEntity(MapEntryNode entityTypeNode, MapEntryNode entityNode) {
 354                 if(hasCandidate(entityNode, owner)) {
 355                     YangInstanceIdentifier entityId =
 356                             (YangInstanceIdentifier)entityNode.getIdentifier().getKeyValues().get(ENTITY_ID_QNAME);
 357                     YangInstanceIdentifier candidatePath = candidatePath(
 358                             entityTypeNode.getIdentifier().getKeyValues().get(ENTITY_TYPE_QNAME).toString(),
 359                             entityId, owner);
 360
 361                     LOG.info("{}: Found entity {}, removing candidate {}, path {}", persistenceId(), entityId,
 362                             owner, candidatePath);
 363
 364                     modifications.addModification(new DeleteModification(candidatePath));
 365                 }
 366             }
 367         });
 368
 369         commitCoordinator.commitModifications(modifications, this);
 370     }
 371
 372     private static boolean hasCandidate(MapEntryNode entity, String candidateName) {
 373         return ((MapNode)entity.getChild(CANDIDATE_NODE_ID).get()).getChild(candidateNodeKey(candidateName)).isPresent();
 374     }
 375
 376     private void searchForEntitiesOwnedBy(final String owner, final EntityWalker walker) {
 377         Optional<NormalizedNode<?, ?>> possibleEntityTypes = getDataStore().readNode(ENTITY_TYPES_PATH);
 378         if(!possibleEntityTypes.isPresent()) {
 379             return;
 380         }
 381
 382         LOG.debug("{}: Searching for entities owned by {}", persistenceId(), owner);
 383
 384         searchForEntities(new EntityWalker() {
 385             @Override
 386             public void onEntity(MapEntryNode entityTypeNode, MapEntryNode entityNode) {
 387                 Optional<DataContainerChild<? extends PathArgument, ?>> possibleOwner =
 388                         entityNode.getChild(ENTITY_OWNER_NODE_ID);
 389                 if(possibleOwner.isPresent() && owner.equals(possibleOwner.get().getValue().toString())) {
 390                     walker.onEntity(entityTypeNode, entityNode);
 391                 }
 392             }
 393         });
 394     }
 395
 396     private void searchForEntities(EntityWalker walker) {
 397         Optional<NormalizedNode<?, ?>> possibleEntityTypes = getDataStore().readNode(ENTITY_TYPES_PATH);
 398         if(!possibleEntityTypes.isPresent()) {
 399             return;
 400         }
 401
 402         for(MapEntryNode entityType:  ((MapNode) possibleEntityTypes.get()).getValue()) {
 403             Optional<DataContainerChild<? extends PathArgument, ?>> possibleEntities =
 404                     entityType.getChild(ENTITY_NODE_ID);
 405             if(!possibleEntities.isPresent()) {
 406                 continue; // shouldn't happen but handle anyway
 407             }
 408
 409             for(MapEntryNode entity:  ((MapNode) possibleEntities.get()).getValue()) {
 410                 walker.onEntity(entityType, entity);
 411             }
 412         }
 413     }
 414
 415     private static Collection<String> getCandidateNames(MapEntryNode entity) {
 416         Collection<MapEntryNode> candidates = ((MapNode)entity.getChild(CANDIDATE_NODE_ID).get()).getValue();
 417         Collection<String> candidateNames = new ArrayList<>(candidates.size());
 418         for(MapEntryNode candidate: candidates) {
 419             candidateNames.add(candidate.getChild(CANDIDATE_NAME_NODE_ID).get().getValue().toString());
 420         }
 421
 422         return candidateNames;
 423     }
 424
 425     private void writeNewOwner(YangInstanceIdentifier entityPath, String newOwner) {
 426         LOG.debug("{}: Writing new owner {} for entity {}", persistenceId(), newOwner, entityPath);
 427
 428         commitCoordinator.commitModification(new WriteModification(entityPath.node(ENTITY_OWNER_QNAME),
 429                 ImmutableNodes.leafNode(ENTITY_OWNER_NODE_ID, newOwner)), this);
 430     }
 431
 432     private String newOwner(Collection<String> candidates, EntityOwnerSelectionStrategy ownerSelectionStrategy) {
 433         Collection<String> viableCandidates = getViableCandidates(candidates);
 434         if(viableCandidates.size() == 0){
 435             return "";
 436         }
 437         return ownerSelectionStrategy.newOwner(viableCandidates);
 438     }
 439
 440     private Collection<String> getViableCandidates(Collection<String> candidates) {
 441         Collection<String> viableCandidates = new ArrayList<>();
 442
 443         for (String candidate : candidates) {
 444             if (!downPeerMemberNames.contains(candidate)) {
 445                 viableCandidates.add(candidate);
 446             }
 447         }
 448         return viableCandidates;
 449     }
 450
 451     private String getCurrentOwner(YangInstanceIdentifier entityId) {
 452         Optional<NormalizedNode<?, ?>> optionalEntityOwner = getDataStore().readNode(entityId.node(ENTITY_OWNER_QNAME));
 453         if(optionalEntityOwner.isPresent()){
 454             return optionalEntityOwner.get().getValue().toString();
 455         }
 456         return null;
 457     }
 458
 459     private static interface EntityWalker {
 460         void onEntity(MapEntryNode entityTypeNode, MapEntryNode entityNode);
 461     }
 462
 463     public static Builder newBuilder() {
 464         return new Builder();
 465     }
 466
 467     static class Builder extends Shard.AbstractBuilder<Builder, EntityOwnershipShard> {
 468         private String localMemberName;
 469
 470         protected Builder() {
 471             super(EntityOwnershipShard.class);
 472         }
 473
 474         Builder localMemberName(String localMemberName) {
 475             checkSealed();
 476             this.localMemberName = localMemberName;
 477             return this;
 478         }
 479
 480         @Override
 481         protected void verify() {
 482             super.verify();
 483             Preconditions.checkNotNull(localMemberName, "localMemberName should not be null");
 484         }
 485     }
 486 }