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_NODE_ID;
  11 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_ID_NODE_ID;
  12 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_ID_QNAME;
  13 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_NODE_ID;
  14 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_OWNERS_PATH;
  15 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_OWNER_NODE_ID;
  16 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_OWNER_QNAME;
  17 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_TYPES_PATH;
  18 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_TYPE_NODE_ID;
  19 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.ENTITY_TYPE_QNAME;
  20 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.candidateMapEntry;
  21 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.candidateNodeKey;
  22 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.candidatePath;
  23 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.createEntity;
  24 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.entityOwnersWithCandidate;
  25 import akka.actor.ActorRef;
  26 import akka.actor.ActorSelection;
  27 import akka.actor.Cancellable;
  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.SelectOwner;
  46 import org.opendaylight.controller.cluster.datastore.entityownership.messages.UnregisterCandidateLocal;
  47 import org.opendaylight.controller.cluster.datastore.entityownership.messages.UnregisterListenerLocal;
  48 import org.opendaylight.controller.cluster.datastore.entityownership.selectionstrategy.EntityOwnerSelectionStrategy;
  49 import org.opendaylight.controller.cluster.datastore.entityownership.selectionstrategy.EntityOwnerSelectionStrategyConfig;
  50 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  51 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  52 import org.opendaylight.controller.cluster.datastore.messages.PeerDown;
  53 import org.opendaylight.controller.cluster.datastore.messages.PeerUp;
  54 import org.opendaylight.controller.cluster.datastore.messages.SuccessReply;
  55 import org.opendaylight.controller.cluster.datastore.modification.DeleteModification;
  56 import org.opendaylight.controller.cluster.datastore.modification.MergeModification;
  57 import org.opendaylight.controller.cluster.datastore.modification.WriteModification;
  58 import org.opendaylight.controller.cluster.raft.RaftState;
  59 import org.opendaylight.controller.md.sal.common.api.clustering.Entity;
  60 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  61 import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
  62 import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
  63 import org.opendaylight.yangtools.yang.data.api.schema.MapNode;
  64 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  65 import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNodes;
  66 import scala.concurrent.Future;
  67 import scala.concurrent.duration.FiniteDuration;
  68
  69 /**
  70  * Special Shard for EntityOwnership.
  71  *
  72  * @author Thomas Pantelis
  73  */
  74 class EntityOwnershipShard extends Shard {
  75     private final String localMemberName;
  76     private final EntityOwnershipShardCommitCoordinator commitCoordinator;
  77     private final EntityOwnershipListenerSupport listenerSupport;
  78     private final Set<String> downPeerMemberNames = new HashSet<>();
  79     private final Map<String, String> peerIdToMemberNames = new HashMap<>();
  80     private final EntityOwnerSelectionStrategyConfig strategyConfig;
  81     private final Map<YangInstanceIdentifier, Cancellable> entityToScheduledOwnershipTask = new HashMap<>();
  82     private final EntityOwnershipStatistics entityOwnershipStatistics;
  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         this.strategyConfig = builder.ownerSelectionStrategyConfig;
  94         this.entityOwnershipStatistics = new EntityOwnershipStatistics();
  95         this.entityOwnershipStatistics.init(getDataStore());
  96
  97         for(String peerId: getRaftActorContext().getPeerIds()) {
  98             ShardIdentifier shardId = ShardIdentifier.builder().fromShardIdString(peerId).build();
  99             peerIdToMemberNames.put(peerId, shardId.getMemberName());
 100         }
 101     }
 102
 103     @Override
 104     protected void onDatastoreContext(DatastoreContext context) {
 105         super.onDatastoreContext(noPersistenceDatastoreContext(context));
 106     }
 107
 108     @Override
 109     protected void onRecoveryComplete() {
 110         super.onRecoveryComplete();
 111
 112         new CandidateListChangeListener(getSelf(), persistenceId()).init(getDataStore());
 113         new EntityOwnerChangeListener(localMemberName, listenerSupport).init(getDataStore());
 114     }
 115
 116     @Override
 117     public void handleNonRaftCommand(final Object message) {
 118         if(message instanceof RegisterCandidateLocal) {
 119             onRegisterCandidateLocal((RegisterCandidateLocal) message);
 120         } else if(message instanceof UnregisterCandidateLocal) {
 121             onUnregisterCandidateLocal((UnregisterCandidateLocal)message);
 122         } else if(message instanceof CandidateAdded){
 123             onCandidateAdded((CandidateAdded) message);
 124         } else if(message instanceof CandidateRemoved){
 125             onCandidateRemoved((CandidateRemoved) message);
 126         } else if(message instanceof PeerDown) {
 127             onPeerDown((PeerDown) message);
 128         } else if(message instanceof PeerUp) {
 129             onPeerUp((PeerUp) message);
 130         } else if(message instanceof RegisterListenerLocal) {
 131             onRegisterListenerLocal((RegisterListenerLocal)message);
 132         } else if(message instanceof UnregisterListenerLocal) {
 133             onUnregisterListenerLocal((UnregisterListenerLocal) message);
 134         } else if(message instanceof SelectOwner) {
 135             onSelectOwner((SelectOwner) message);
 136         } else if(!commitCoordinator.handleMessage(message, this)) {
 137             super.handleNonRaftCommand(message);
 138         }
 139     }
 140
 141     private void onSelectOwner(SelectOwner selectOwner) {
 142         LOG.debug("{}: onSelectOwner: {}", persistenceId(), selectOwner);
 143
 144         String currentOwner = getCurrentOwner(selectOwner.getEntityPath());
 145         if(Strings.isNullOrEmpty(currentOwner)) {
 146             String entityType = EntityOwnersModel.entityTypeFromEntityPath(selectOwner.getEntityPath());
 147             writeNewOwner(selectOwner.getEntityPath(), newOwner(currentOwner, selectOwner.getAllCandidates(),
 148                     entityOwnershipStatistics.byEntityType(entityType),
 149                     selectOwner.getOwnerSelectionStrategy()));
 150
 151             Cancellable cancellable = entityToScheduledOwnershipTask.get(selectOwner.getEntityPath());
 152             if(cancellable != null){
 153                 if(!cancellable.isCancelled()){
 154                     cancellable.cancel();
 155                 }
 156                 entityToScheduledOwnershipTask.remove(selectOwner.getEntityPath());
 157             }
 158         }
 159     }
 160
 161     private void onRegisterCandidateLocal(RegisterCandidateLocal registerCandidate) {
 162         LOG.debug("{}: onRegisterCandidateLocal: {}", persistenceId(), registerCandidate);
 163
 164         listenerSupport.setHasCandidateForEntity(registerCandidate.getEntity());
 165
 166         NormalizedNode<?, ?> entityOwners = entityOwnersWithCandidate(registerCandidate.getEntity().getType(),
 167                 registerCandidate.getEntity().getId(), localMemberName);
 168         commitCoordinator.commitModification(new MergeModification(ENTITY_OWNERS_PATH, entityOwners), this);
 169
 170         getSender().tell(SuccessReply.INSTANCE, getSelf());
 171     }
 172
 173     private void onUnregisterCandidateLocal(UnregisterCandidateLocal unregisterCandidate) {
 174         LOG.debug("{}: onUnregisterCandidateLocal: {}", persistenceId(), unregisterCandidate);
 175
 176         Entity entity = unregisterCandidate.getEntity();
 177         listenerSupport.unsetHasCandidateForEntity(entity);
 178
 179         YangInstanceIdentifier candidatePath = candidatePath(entity.getType(), entity.getId(), localMemberName);
 180         commitCoordinator.commitModification(new DeleteModification(candidatePath), this);
 181
 182         getSender().tell(SuccessReply.INSTANCE, getSelf());
 183     }
 184
 185     private void onRegisterListenerLocal(final RegisterListenerLocal registerListener) {
 186         LOG.debug("{}: onRegisterListenerLocal: {}", persistenceId(), registerListener);
 187
 188         listenerSupport.addEntityOwnershipListener(registerListener.getEntityType(), registerListener.getListener());
 189
 190         getSender().tell(SuccessReply.INSTANCE, getSelf());
 191
 192         searchForEntities(new EntityWalker() {
 193             @Override
 194             public void onEntity(MapEntryNode entityTypeNode, MapEntryNode entityNode) {
 195                 Optional<DataContainerChild<?, ?>> possibleType = entityTypeNode.getChild(ENTITY_TYPE_NODE_ID);
 196                 String entityType = possibleType.isPresent() ? possibleType.get().getValue().toString() : null;
 197                 if (registerListener.getEntityType().equals(entityType)) {
 198                     final boolean hasOwner;
 199                     final boolean isOwner;
 200
 201                     Optional<DataContainerChild<?, ?>> possibleOwner = entityNode.getChild(ENTITY_OWNER_NODE_ID);
 202                     if (possibleOwner.isPresent()) {
 203                         isOwner = localMemberName.equals(possibleOwner.get().getValue().toString());
 204                         hasOwner = true;
 205                     } else {
 206                         isOwner = false;
 207                         hasOwner = false;
 208                     }
 209
 210                     Entity entity = new Entity(entityType,
 211                         (YangInstanceIdentifier) entityNode.getChild(ENTITY_ID_NODE_ID).get().getValue());
 212
 213                     listenerSupport.notifyEntityOwnershipListener(entity, false, isOwner, hasOwner,
 214                         registerListener.getListener());
 215                 }
 216             }
 217         });
 218     }
 219
 220     private void onUnregisterListenerLocal(UnregisterListenerLocal unregisterListener) {
 221         LOG.debug("{}: onUnregisterListenerLocal: {}", persistenceId(), unregisterListener);
 222
 223         listenerSupport.removeEntityOwnershipListener(unregisterListener.getEntityType(), unregisterListener.getListener());
 224
 225         getSender().tell(SuccessReply.INSTANCE, getSelf());
 226     }
 227
 228     void tryCommitModifications(final BatchedModifications modifications) {
 229         if(isLeader()) {
 230             LOG.debug("{}: Committing BatchedModifications {} locally", persistenceId(), modifications.getTransactionID());
 231
 232             // Note that it's possible the commit won't get consensus and will timeout and not be applied
 233             // to the state. However we don't need to retry it in that case b/c it will be committed to
 234             // the journal first and, once a majority of followers come back on line and it is replicated,
 235             // it will be applied at that point.
 236             handleBatchedModificationsLocal(modifications, self());
 237         } else {
 238             final ActorSelection leader = getLeader();
 239             if (leader != null) {
 240                 if(LOG.isDebugEnabled()) {
 241                     LOG.debug("{}: Sending BatchedModifications {} to leader {}", persistenceId(),
 242                             modifications.getTransactionID(), leader);
 243                 }
 244
 245                 Future<Object> future = Patterns.ask(leader, modifications, TimeUnit.SECONDS.toMillis(
 246                         getDatastoreContext().getShardTransactionCommitTimeoutInSeconds()));
 247
 248                 Patterns.pipe(future, getContext().dispatcher()).pipeTo(getSelf(), ActorRef.noSender());
 249             }
 250         }
 251     }
 252
 253     boolean hasLeader() {
 254         return getLeader() != null && !isIsolatedLeader();
 255     }
 256
 257     /**
 258      * Determine if we are in jeopardy based on observed RAFT state.
 259      */
 260     private static boolean inJeopardy(final RaftState state) {
 261         switch (state) {
 262             case Candidate:
 263             case Follower:
 264             case Leader:
 265                 return false;
 266             case IsolatedLeader:
 267                 return true;
 268         }
 269         throw new IllegalStateException("Unsupported RAFT state " + state);
 270     }
 271
 272     private void notifyAllListeners() {
 273         searchForEntities(new EntityWalker() {
 274             @Override
 275             public void onEntity(MapEntryNode entityTypeNode, MapEntryNode entityNode) {
 276                 Optional<DataContainerChild<?, ?>> possibleType = entityTypeNode.getChild(ENTITY_TYPE_NODE_ID);
 277                 if (possibleType.isPresent()) {
 278                     final boolean hasOwner;
 279                     final boolean isOwner;
 280
 281                     Optional<DataContainerChild<?, ?>> possibleOwner = entityNode.getChild(ENTITY_OWNER_NODE_ID);
 282                     if (possibleOwner.isPresent()) {
 283                         isOwner = localMemberName.equals(possibleOwner.get().getValue().toString());
 284                         hasOwner = true;
 285                     } else {
 286                         isOwner = false;
 287                         hasOwner = false;
 288                     }
 289
 290                     Entity entity = new Entity(possibleType.get().getValue().toString(),
 291                         (YangInstanceIdentifier) entityNode.getChild(ENTITY_ID_NODE_ID).get().getValue());
 292
 293                     listenerSupport.notifyEntityOwnershipListeners(entity, isOwner, isOwner, hasOwner);
 294                 }
 295             }
 296         });
 297     }
 298
 299     @Override
 300     protected void onStateChanged() {
 301         super.onStateChanged();
 302
 303         boolean isLeader = isLeader();
 304         LOG.debug("{}: onStateChanged: isLeader: {}, hasLeader: {}", persistenceId(), isLeader, hasLeader());
 305
 306         // Examine current RAFT state to see if we are in jeopardy, potentially notifying all listeners
 307         final boolean inJeopardy = inJeopardy(getRaftState());
 308         final boolean wasInJeopardy = listenerSupport.setInJeopardy(inJeopardy);
 309         if (inJeopardy != wasInJeopardy) {
 310             LOG.debug("{}: {} jeopardy state, notifying all listeners", persistenceId(),
 311                 inJeopardy ? "entered" : "left");
 312             notifyAllListeners();
 313         }
 314
 315         commitCoordinator.onStateChanged(this, isLeader);
 316     }
 317
 318     @Override
 319     protected void onLeaderChanged(String oldLeader, String newLeader) {
 320         super.onLeaderChanged(oldLeader, newLeader);
 321
 322         boolean isLeader = isLeader();
 323         LOG.debug("{}: onLeaderChanged: oldLeader: {}, newLeader: {}, isLeader: {}", persistenceId(), oldLeader,
 324                 newLeader, isLeader);
 325
 326         if(isLeader) {
 327
 328             // Clear all existing strategies so that they get re-created when we call createStrategy again
 329             // This allows the strategies to be re-initialized with existing statistics maintained by
 330             // EntityOwnershipStatistics
 331             strategyConfig.clearStrategies();
 332
 333             // Remove the candidates for all members that are known to be down. In a cluster which has greater than
 334             // 3 nodes it is possible for a some node beside the leader being down when the leadership transitions
 335             // it makes sense to use this event to remove all the candidates for those downed nodes
 336             for(String downPeerName : downPeerMemberNames){
 337                 removeCandidateFromEntities(downPeerName);
 338             }
 339         } else {
 340             // The leader changed - notify the coordinator to check if pending modifications need to be sent.
 341             // While onStateChanged also does this, this method handles the case where the shard hears from a
 342             // leader and stays in the follower state. In that case no behavior state change occurs.
 343             commitCoordinator.onStateChanged(this, isLeader);
 344         }
 345     }
 346
 347     private void onCandidateRemoved(CandidateRemoved message) {
 348         LOG.debug("{}: onCandidateRemoved: {}", persistenceId(), message);
 349
 350         if(isLeader()) {
 351             String currentOwner = getCurrentOwner(message.getEntityPath());
 352             if(message.getRemovedCandidate().equals(currentOwner) || message.getRemainingCandidates().size() == 0){
 353                 String entityType = EntityOwnersModel.entityTypeFromEntityPath(message.getEntityPath());
 354                 writeNewOwner(message.getEntityPath(),
 355                         newOwner(currentOwner, message.getRemainingCandidates(), entityOwnershipStatistics.byEntityType(entityType),
 356                                 getEntityOwnerElectionStrategy(message.getEntityPath())));
 357             }
 358         } else {
 359             // We're not the leader. If the removed candidate is our local member then check if we actually
 360             // have a local candidate registered. If we do then we must have been partitioned from the leader
 361             // and the leader removed our candidate since the leader can't tell the difference between a
 362             // temporary network partition and a node's process actually restarted. So, in that case, re-add
 363             // our candidate.
 364             if(localMemberName.equals(message.getRemovedCandidate()) &&
 365                     listenerSupport.hasCandidateForEntity(createEntity(message.getEntityPath()))) {
 366                 LOG.debug("Local candidate member was removed but a local candidate is registered for {}" +
 367                     " - adding back local candidate", message.getEntityPath());
 368
 369                 commitCoordinator.commitModification(new MergeModification(
 370                         candidatePath(message.getEntityPath(), localMemberName),
 371                         candidateMapEntry(localMemberName)), this);
 372             }
 373         }
 374     }
 375
 376     private EntityOwnerSelectionStrategy getEntityOwnerElectionStrategy(YangInstanceIdentifier entityPath) {
 377         final String entityType = EntityOwnersModel.entityTypeFromEntityPath(entityPath);
 378         return strategyConfig.createStrategy(entityType, entityOwnershipStatistics.byEntityType(entityType));
 379     }
 380
 381     private void onCandidateAdded(CandidateAdded message) {
 382         if(!isLeader()){
 383             return;
 384         }
 385
 386         LOG.debug("{}: onCandidateAdded: {}", persistenceId(), message);
 387
 388         // Since a node's candidate member is only added by the node itself, we can assume the node is up so
 389         // remove it from the downPeerMemberNames.
 390         downPeerMemberNames.remove(message.getNewCandidate());
 391
 392         final String currentOwner = getCurrentOwner(message.getEntityPath());
 393         final EntityOwnerSelectionStrategy strategy = getEntityOwnerElectionStrategy(message.getEntityPath());
 394         final String entityType = EntityOwnersModel.entityTypeFromEntityPath(message.getEntityPath());
 395
 396         // Available members is all the known peers - the number of peers that are down + self
 397         // So if there are 2 peers and 1 is down then availableMembers will be 2
 398         final int availableMembers = (peerIdToMemberNames.size() - downPeerMemberNames.size()) + 1;
 399
 400         LOG.debug("{}: Using strategy {} to select owner, currentOwner = {}", persistenceId(), strategy, currentOwner);
 401
 402         if(!message.getAllCandidates().contains(currentOwner)){
 403             if(strategy.getSelectionDelayInMillis() == 0L) {
 404                 writeNewOwner(message.getEntityPath(), newOwner(currentOwner, message.getAllCandidates(),
 405                         entityOwnershipStatistics.byEntityType(entityType), strategy));
 406             } else if(message.getAllCandidates().size() == availableMembers) {
 407                 LOG.debug("{}: Received the maximum candidates requests : {} writing new owner",
 408                         persistenceId(), availableMembers);
 409                 cancelOwnerSelectionTask(message.getEntityPath());
 410                 writeNewOwner(message.getEntityPath(), newOwner(currentOwner, message.getAllCandidates(),
 411                         entityOwnershipStatistics.byEntityType(entityType), strategy));
 412             } else {
 413                 scheduleOwnerSelection(message.getEntityPath(), message.getAllCandidates(), strategy);
 414             }
 415         }
 416     }
 417
 418     private void onPeerDown(PeerDown peerDown) {
 419         LOG.info("{}: onPeerDown: {}", persistenceId(), peerDown);
 420
 421         String downMemberName = peerDown.getMemberName();
 422         if(downPeerMemberNames.add(downMemberName) && isLeader()) {
 423             // Remove the down peer as a candidate from all entities.
 424             removeCandidateFromEntities(downMemberName);
 425         }
 426     }
 427
 428     private void onPeerUp(PeerUp peerUp) {
 429         LOG.debug("{}: onPeerUp: {}", persistenceId(), peerUp);
 430
 431         peerIdToMemberNames.put(peerUp.getPeerId(), peerUp.getMemberName());
 432         downPeerMemberNames.remove(peerUp.getMemberName());
 433
 434         // Notify the coordinator to check if pending modifications need to be sent. We do this here
 435         // to handle the case where the leader's peer address isn't now yet when a prior state or
 436         // leader change occurred.
 437         commitCoordinator.onStateChanged(this, isLeader());
 438     }
 439
 440     private void removeCandidateFromEntities(final String owner) {
 441         final BatchedModifications modifications = commitCoordinator.newBatchedModifications();
 442         searchForEntities(new EntityWalker() {
 443             @Override
 444             public void onEntity(MapEntryNode entityTypeNode, MapEntryNode entityNode) {
 445                 if (hasCandidate(entityNode, owner)) {
 446                     YangInstanceIdentifier entityId =
 447                             (YangInstanceIdentifier) entityNode.getIdentifier().getKeyValues().get(ENTITY_ID_QNAME);
 448                     YangInstanceIdentifier candidatePath = candidatePath(
 449                             entityTypeNode.getIdentifier().getKeyValues().get(ENTITY_TYPE_QNAME).toString(),
 450                             entityId, owner);
 451
 452                     LOG.info("{}: Found entity {}, removing candidate {}, path {}", persistenceId(), entityId,
 453                             owner, candidatePath);
 454
 455                     modifications.addModification(new DeleteModification(candidatePath));
 456                 }
 457             }
 458         });
 459
 460         commitCoordinator.commitModifications(modifications, this);
 461     }
 462
 463     private static boolean hasCandidate(MapEntryNode entity, String candidateName) {
 464         return ((MapNode)entity.getChild(CANDIDATE_NODE_ID).get()).getChild(candidateNodeKey(candidateName)).isPresent();
 465     }
 466
 467     private void searchForEntities(EntityWalker walker) {
 468         Optional<NormalizedNode<?, ?>> possibleEntityTypes = getDataStore().readNode(ENTITY_TYPES_PATH);
 469         if(!possibleEntityTypes.isPresent()) {
 470             return;
 471         }
 472
 473         for(MapEntryNode entityType:  ((MapNode) possibleEntityTypes.get()).getValue()) {
 474             Optional<DataContainerChild<?, ?>> possibleEntities = entityType.getChild(ENTITY_NODE_ID);
 475             if(!possibleEntities.isPresent()) {
 476                 // shouldn't happen but handle anyway
 477                 continue;
 478             }
 479
 480             for(MapEntryNode entity:  ((MapNode) possibleEntities.get()).getValue()) {
 481                 walker.onEntity(entityType, entity);
 482             }
 483         }
 484     }
 485
 486     private void writeNewOwner(YangInstanceIdentifier entityPath, String newOwner) {
 487         LOG.debug("{}: Writing new owner {} for entity {}", persistenceId(), newOwner, entityPath);
 488
 489         commitCoordinator.commitModification(new WriteModification(entityPath.node(ENTITY_OWNER_QNAME),
 490                 ImmutableNodes.leafNode(ENTITY_OWNER_NODE_ID, newOwner)), this);
 491     }
 492
 493     /**
 494      * Schedule a new owner selection job. Cancelling any outstanding job if it has not been cancelled.
 495      *
 496      * @param entityPath
 497      * @param allCandidates
 498      */
 499     public void scheduleOwnerSelection(YangInstanceIdentifier entityPath, Collection<String> allCandidates,
 500                                        EntityOwnerSelectionStrategy strategy){
 501         cancelOwnerSelectionTask(entityPath);
 502
 503         LOG.debug("{}: Scheduling owner selection after {} ms", persistenceId(), strategy.getSelectionDelayInMillis());
 504
 505         final Cancellable lastScheduledTask = context().system().scheduler().scheduleOnce(
 506                 FiniteDuration.apply(strategy.getSelectionDelayInMillis(), TimeUnit.MILLISECONDS)
 507                 , self(), new SelectOwner(entityPath, allCandidates, strategy)
 508                 , context().system().dispatcher(), self());
 509
 510         entityToScheduledOwnershipTask.put(entityPath, lastScheduledTask);
 511     }
 512
 513     private void cancelOwnerSelectionTask(YangInstanceIdentifier entityPath){
 514         final Cancellable lastScheduledTask = entityToScheduledOwnershipTask.get(entityPath);
 515         if(lastScheduledTask != null && !lastScheduledTask.isCancelled()){
 516             lastScheduledTask.cancel();
 517         }
 518     }
 519
 520     private String newOwner(String currentOwner, Collection<String> candidates, Map<String, Long> statistics, EntityOwnerSelectionStrategy ownerSelectionStrategy) {
 521         Collection<String> viableCandidates = getViableCandidates(candidates);
 522         if(viableCandidates.size() == 0){
 523             return "";
 524         }
 525         return ownerSelectionStrategy.newOwner(currentOwner, viableCandidates);
 526     }
 527
 528     private Collection<String> getViableCandidates(Collection<String> candidates) {
 529         Collection<String> viableCandidates = new ArrayList<>();
 530
 531         for (String candidate : candidates) {
 532             if (!downPeerMemberNames.contains(candidate)) {
 533                 viableCandidates.add(candidate);
 534             }
 535         }
 536         return viableCandidates;
 537     }
 538
 539     private String getCurrentOwner(YangInstanceIdentifier entityId) {
 540         Optional<NormalizedNode<?, ?>> optionalEntityOwner = getDataStore().readNode(entityId.node(ENTITY_OWNER_QNAME));
 541         if(optionalEntityOwner.isPresent()){
 542             return optionalEntityOwner.get().getValue().toString();
 543         }
 544         return null;
 545     }
 546
 547     private static interface EntityWalker {
 548         void onEntity(MapEntryNode entityTypeNode, MapEntryNode entityNode);
 549     }
 550
 551     public static Builder newBuilder() {
 552         return new Builder();
 553     }
 554
 555     static class Builder extends Shard.AbstractBuilder<Builder, EntityOwnershipShard> {
 556         private String localMemberName;
 557         private EntityOwnerSelectionStrategyConfig ownerSelectionStrategyConfig;
 558
 559         protected Builder() {
 560             super(EntityOwnershipShard.class);
 561         }
 562
 563         Builder localMemberName(String localMemberName) {
 564             checkSealed();
 565             this.localMemberName = localMemberName;
 566             return this;
 567         }
 568
 569         Builder ownerSelectionStrategyConfig(EntityOwnerSelectionStrategyConfig ownerSelectionStrategyConfig){
 570             checkSealed();
 571             this.ownerSelectionStrategyConfig = ownerSelectionStrategyConfig;
 572             return this;
 573         }
 574
 575         @Override
 576         protected void verify() {
 577             super.verify();
 578             Preconditions.checkNotNull(localMemberName, "localMemberName should not be null");
 579             Preconditions.checkNotNull(ownerSelectionStrategyConfig, "ownerSelectionStrategyConfig should not be null");
 580         }
 581     }
 582 }