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

   1 /*
   2  * Copyright (c) 2014 Cisco 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
   9 package org.opendaylight.controller.cluster.datastore;
  10
  11 import akka.actor.ActorRef;
  12 import akka.actor.ActorSelection;
  13 import akka.actor.PoisonPill;
  14 import akka.actor.Props;
  15 import akka.event.Logging;
  16 import akka.event.LoggingAdapter;
  17 import akka.japi.Creator;
  18 import akka.persistence.RecoveryFailure;
  19 import akka.serialization.Serialization;
  20 import com.google.common.annotations.VisibleForTesting;
  21 import com.google.common.base.Optional;
  22 import com.google.common.base.Preconditions;
  23 import com.google.common.util.concurrent.CheckedFuture;
  24 import com.google.common.util.concurrent.FutureCallback;
  25 import com.google.common.util.concurrent.Futures;
  26 import com.google.common.util.concurrent.ListenableFuture;
  27 import com.google.protobuf.ByteString;
  28 import com.google.protobuf.InvalidProtocolBufferException;
  29 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
  30 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
  31 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  32 import org.opendaylight.controller.cluster.datastore.identifiers.ShardTransactionIdentifier;
  33 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardMBeanFactory;
  34 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
  35 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  36 import org.opendaylight.controller.cluster.datastore.messages.CommitTransactionReply;
  37 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  38 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionChainReply;
  39 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  40 import org.opendaylight.controller.cluster.datastore.messages.EnableNotification;
  41 import org.opendaylight.controller.cluster.datastore.messages.ForwardedCommitTransaction;
  42 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
  43 import org.opendaylight.controller.cluster.datastore.messages.ReadData;
  44 import org.opendaylight.controller.cluster.datastore.messages.ReadDataReply;
  45 import org.opendaylight.controller.cluster.datastore.messages.RegisterChangeListener;
  46 import org.opendaylight.controller.cluster.datastore.messages.RegisterChangeListenerReply;
  47 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
  48 import org.opendaylight.controller.cluster.datastore.modification.Modification;
  49 import org.opendaylight.controller.cluster.datastore.modification.MutableCompositeModification;
  50 import org.opendaylight.controller.cluster.datastore.node.NormalizedNodeToNodeCodec;
  51 import org.opendaylight.controller.cluster.raft.ConfigParams;
  52 import org.opendaylight.controller.cluster.raft.DefaultConfigParamsImpl;
  53 import org.opendaylight.controller.cluster.raft.RaftActor;
  54 import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry;
  55 import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshotReply;
  56 import org.opendaylight.controller.md.sal.common.api.data.AsyncDataChangeListener;
  57 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
  58 import org.opendaylight.controller.md.sal.dom.store.impl.InMemoryDOMDataStore;
  59 import org.opendaylight.controller.md.sal.dom.store.impl.InMemoryDOMDataStoreFactory;
  60 import org.opendaylight.controller.protobuff.messages.common.NormalizedNodeMessages;
  61 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadTransaction;
  62 import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
  63 import org.opendaylight.controller.sal.core.spi.data.DOMStoreTransactionChain;
  64 import org.opendaylight.controller.sal.core.spi.data.DOMStoreTransactionFactory;
  65 import org.opendaylight.controller.sal.core.spi.data.DOMStoreWriteTransaction;
  66 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  67 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  68 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  69 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  70 import scala.concurrent.duration.FiniteDuration;
  71
  72 import java.util.ArrayList;
  73 import java.util.HashMap;
  74 import java.util.List;
  75 import java.util.Map;
  76 import java.util.concurrent.ExecutionException;
  77 import java.util.concurrent.TimeUnit;
  78
  79 /**
  80  * A Shard represents a portion of the logical data tree <br/>
  81  * <p>
  82  * Our Shard uses InMemoryDataStore as it's internal representation and delegates all requests it
  83  * </p>
  84  */
  85 public class Shard extends RaftActor {
  86
  87     private static final ConfigParams configParams = new ShardConfigParams();
  88
  89     public static final String DEFAULT_NAME = "default";
  90
  91     // The state of this Shard
  92     private final InMemoryDOMDataStore store;
  93
  94     private final Map<Object, DOMStoreThreePhaseCommitCohort>
  95         modificationToCohort = new HashMap<>();
  96
  97     private final LoggingAdapter LOG =
  98         Logging.getLogger(getContext().system(), this);
  99
 100     // By default persistent will be true and can be turned off using the system
 101     // property shard.persistent
 102     private final boolean persistent;
 103
 104     /// The name of this shard
 105     private final ShardIdentifier name;
 106
 107     private final ShardStats shardMBean;
 108
 109     private final List<ActorSelection> dataChangeListeners = new ArrayList<>();
 110
 111     private final DatastoreContext datastoreContext;
 112
 113     private SchemaContext schemaContext;
 114
 115     private ActorRef createSnapshotTransaction;
 116
 117     private final Map<String, DOMStoreTransactionChain> transactionChains = new HashMap<>();
 118
 119     private Shard(ShardIdentifier name, Map<ShardIdentifier, String> peerAddresses,
 120             DatastoreContext datastoreContext, SchemaContext schemaContext) {
 121         super(name.toString(), mapPeerAddresses(peerAddresses), Optional.of(configParams));
 122
 123         this.name = name;
 124         this.datastoreContext = datastoreContext;
 125         this.schemaContext = schemaContext;
 126
 127         String setting = System.getProperty("shard.persistent");
 128
 129         this.persistent = !"false".equals(setting);
 130
 131         LOG.info("Shard created : {} persistent : {}", name, persistent);
 132
 133         store = InMemoryDOMDataStoreFactory.create(name.toString(), null,
 134                 datastoreContext.getDataStoreProperties());
 135
 136         if(schemaContext != null) {
 137             store.onGlobalContextUpdated(schemaContext);
 138         }
 139
 140         shardMBean = ShardMBeanFactory.getShardStatsMBean(name.toString(),
 141                 datastoreContext.getDataStoreMXBeanType());
 142         shardMBean.setDataStoreExecutor(store.getDomStoreExecutor());
 143         shardMBean.setNotificationManager(store.getDataChangeListenerNotificationManager());
 144
 145         if (isMetricsCaptureEnabled()) {
 146             getContext().become(new MeteringBehavior(this));
 147         }
 148     }
 149
 150     private static Map<String, String> mapPeerAddresses(
 151         Map<ShardIdentifier, String> peerAddresses) {
 152         Map<String, String> map = new HashMap<>();
 153
 154         for (Map.Entry<ShardIdentifier, String> entry : peerAddresses
 155             .entrySet()) {
 156             map.put(entry.getKey().toString(), entry.getValue());
 157         }
 158
 159         return map;
 160     }
 161
 162     public static Props props(final ShardIdentifier name,
 163         final Map<ShardIdentifier, String> peerAddresses,
 164         DatastoreContext datastoreContext, SchemaContext schemaContext) {
 165         Preconditions.checkNotNull(name, "name should not be null");
 166         Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
 167         Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
 168         Preconditions.checkNotNull(schemaContext, "schemaContext should not be null");
 169
 170         return Props.create(new ShardCreator(name, peerAddresses, datastoreContext, schemaContext));
 171     }
 172
 173     @Override public void onReceiveRecover(Object message) {
 174         LOG.debug("onReceiveRecover: Received message {} from {}", message.getClass().toString(),
 175             getSender());
 176
 177         if (message instanceof RecoveryFailure){
 178             LOG.error(((RecoveryFailure) message).cause(), "Recovery failed because of this cause");
 179         } else {
 180             super.onReceiveRecover(message);
 181         }
 182     }
 183
 184     @Override public void onReceiveCommand(Object message) {
 185         LOG.debug("onReceiveCommand: Received message {} from {}", message.getClass().toString(),
 186             getSender());
 187
 188         if(message.getClass().equals(ReadDataReply.SERIALIZABLE_CLASS)) {
 189             // This must be for install snapshot. Don't want to open this up and trigger
 190             // deSerialization
 191             self()
 192                 .tell(new CaptureSnapshotReply(ReadDataReply.getNormalizedNodeByteString(message)),
 193                     self());
 194
 195             // Send a PoisonPill instead of sending close transaction because we do not really need
 196             // a response
 197             getSender().tell(PoisonPill.getInstance(), self());
 198
 199         } else if (message.getClass().equals(CloseTransactionChain.SERIALIZABLE_CLASS)){
 200             closeTransactionChain(CloseTransactionChain.fromSerializable(message));
 201         } else if (message instanceof RegisterChangeListener) {
 202             registerChangeListener((RegisterChangeListener) message);
 203         } else if (message instanceof UpdateSchemaContext) {
 204             updateSchemaContext((UpdateSchemaContext) message);
 205         } else if (message instanceof ForwardedCommitTransaction) {
 206             handleForwardedCommit((ForwardedCommitTransaction) message);
 207         } else if (message.getClass()
 208             .equals(CreateTransaction.SERIALIZABLE_CLASS)) {
 209             if (isLeader()) {
 210                 createTransaction(CreateTransaction.fromSerializable(message));
 211             } else if (getLeader() != null) {
 212                 getLeader().forward(message, getContext());
 213             } else {
 214                 getSender().tell(new akka.actor.Status.Failure(new IllegalStateException(
 215                     "Could not find leader so transaction cannot be created")), getSelf());
 216             }
 217         } else if (message instanceof PeerAddressResolved) {
 218             PeerAddressResolved resolved = (PeerAddressResolved) message;
 219             setPeerAddress(resolved.getPeerId().toString(),
 220                 resolved.getPeerAddress());
 221         } else {
 222             super.onReceiveCommand(message);
 223         }
 224     }
 225
 226     private void closeTransactionChain(CloseTransactionChain closeTransactionChain) {
 227         DOMStoreTransactionChain chain =
 228             transactionChains.remove(closeTransactionChain.getTransactionChainId());
 229
 230         if(chain != null) {
 231             chain.close();
 232         }
 233     }
 234
 235     private ActorRef createTypedTransactionActor(
 236         int transactionType,
 237         ShardTransactionIdentifier transactionId,
 238         String transactionChainId ) {
 239
 240         DOMStoreTransactionFactory factory = store;
 241
 242         if(!transactionChainId.isEmpty()) {
 243             factory = transactionChains.get(transactionChainId);
 244             if(factory == null){
 245                 DOMStoreTransactionChain transactionChain = store.createTransactionChain();
 246                 transactionChains.put(transactionChainId, transactionChain);
 247                 factory = transactionChain;
 248             }
 249         }
 250
 251         if(this.schemaContext == null){
 252             throw new NullPointerException("schemaContext should not be null");
 253         }
 254
 255         if (transactionType
 256             == TransactionProxy.TransactionType.READ_ONLY.ordinal()) {
 257
 258             shardMBean.incrementReadOnlyTransactionCount();
 259
 260             return getContext().actorOf(
 261                 ShardTransaction.props(factory.newReadOnlyTransaction(), getSelf(),
 262                         schemaContext,datastoreContext, shardMBean), transactionId.toString());
 263
 264         } else if (transactionType
 265             == TransactionProxy.TransactionType.READ_WRITE.ordinal()) {
 266
 267             shardMBean.incrementReadWriteTransactionCount();
 268
 269             return getContext().actorOf(
 270                 ShardTransaction.props(factory.newReadWriteTransaction(), getSelf(),
 271                         schemaContext, datastoreContext, shardMBean), transactionId.toString());
 272
 273
 274         } else if (transactionType
 275             == TransactionProxy.TransactionType.WRITE_ONLY.ordinal()) {
 276
 277             shardMBean.incrementWriteOnlyTransactionCount();
 278
 279             return getContext().actorOf(
 280                 ShardTransaction.props(factory.newWriteOnlyTransaction(), getSelf(),
 281                         schemaContext, datastoreContext, shardMBean), transactionId.toString());
 282         } else {
 283             throw new IllegalArgumentException(
 284                 "Shard="+name + ":CreateTransaction message has unidentified transaction type="
 285                     + transactionType);
 286         }
 287     }
 288
 289     private void createTransaction(CreateTransaction createTransaction) {
 290         createTransaction(createTransaction.getTransactionType(),
 291             createTransaction.getTransactionId(), createTransaction.getTransactionChainId());
 292     }
 293
 294     private ActorRef createTransaction(int transactionType, String remoteTransactionId, String transactionChainId) {
 295
 296         ShardTransactionIdentifier transactionId =
 297             ShardTransactionIdentifier.builder()
 298                 .remoteTransactionId(remoteTransactionId)
 299                 .build();
 300         LOG.debug("Creating transaction : {} ", transactionId);
 301         ActorRef transactionActor =
 302             createTypedTransactionActor(transactionType, transactionId, transactionChainId);
 303
 304         getSender()
 305             .tell(new CreateTransactionReply(
 306                     Serialization.serializedActorPath(transactionActor),
 307                     remoteTransactionId).toSerializable(),
 308                 getSelf());
 309
 310         return transactionActor;
 311     }
 312
 313     private void syncCommitTransaction(DOMStoreWriteTransaction transaction)
 314         throws ExecutionException, InterruptedException {
 315         DOMStoreThreePhaseCommitCohort commitCohort = transaction.ready();
 316         commitCohort.preCommit().get();
 317         commitCohort.commit().get();
 318     }
 319
 320
 321     private void commit(final ActorRef sender, Object serialized) {
 322         Modification modification = MutableCompositeModification
 323             .fromSerializable(serialized, schemaContext);
 324         DOMStoreThreePhaseCommitCohort cohort =
 325             modificationToCohort.remove(serialized);
 326         if (cohort == null) {
 327             LOG.debug(
 328                 "Could not find cohort for modification : {}. Writing modification using a new transaction",
 329                 modification);
 330             DOMStoreWriteTransaction transaction =
 331                 store.newWriteOnlyTransaction();
 332
 333             LOG.debug("Created new transaction {}", transaction.getIdentifier().toString());
 334
 335             modification.apply(transaction);
 336             try {
 337                 syncCommitTransaction(transaction);
 338             } catch (InterruptedException | ExecutionException e) {
 339                 shardMBean.incrementFailedTransactionsCount();
 340                 LOG.error("Failed to commit", e);
 341                 return;
 342             }
 343             //we want to just apply the recovery commit and return
 344             shardMBean.incrementCommittedTransactionCount();
 345             return;
 346         }
 347
 348
 349         if(sender == null){
 350             LOG.error("Commit failed. Sender cannot be null");
 351             return;
 352         }
 353
 354         final ListenableFuture<Void> future = cohort.commit();
 355         final ActorRef self = getSelf();
 356
 357         Futures.addCallback(future, new FutureCallback<Void>() {
 358             @Override
 359             public void onSuccess(Void v) {
 360                 sender.tell(new CommitTransactionReply().toSerializable(), self);
 361                 shardMBean.incrementCommittedTransactionCount();
 362                 shardMBean.setLastCommittedTransactionTime(System.currentTimeMillis());
 363             }
 364
 365             @Override
 366             public void onFailure(Throwable t) {
 367                 LOG.error(t, "An exception happened during commit");
 368                 shardMBean.incrementFailedTransactionsCount();
 369                 sender.tell(new akka.actor.Status.Failure(t), self);
 370             }
 371         });
 372
 373     }
 374
 375     private void handleForwardedCommit(ForwardedCommitTransaction message) {
 376         Object serializedModification =
 377             message.getModification().toSerializable();
 378
 379         modificationToCohort
 380             .put(serializedModification, message.getCohort());
 381
 382         if (persistent) {
 383             this.persistData(getSender(), "identifier",
 384                 new CompositeModificationPayload(serializedModification));
 385         } else {
 386             this.commit(getSender(), serializedModification);
 387         }
 388     }
 389
 390     private void updateSchemaContext(UpdateSchemaContext message) {
 391         this.schemaContext = message.getSchemaContext();
 392         updateSchemaContext(message.getSchemaContext());
 393         store.onGlobalContextUpdated(message.getSchemaContext());
 394     }
 395
 396     @VisibleForTesting void updateSchemaContext(SchemaContext schemaContext) {
 397         store.onGlobalContextUpdated(schemaContext);
 398     }
 399
 400     private void registerChangeListener(
 401         RegisterChangeListener registerChangeListener) {
 402
 403         LOG.debug("registerDataChangeListener for {}", registerChangeListener
 404             .getPath());
 405
 406
 407         ActorSelection dataChangeListenerPath = getContext()
 408             .system().actorSelection(
 409                 registerChangeListener.getDataChangeListenerPath());
 410
 411
 412         // Notify the listener if notifications should be enabled or not
 413         // If this shard is the leader then it will enable notifications else
 414         // it will not
 415         dataChangeListenerPath
 416             .tell(new EnableNotification(isLeader()), getSelf());
 417
 418         // Now store a reference to the data change listener so it can be notified
 419         // at a later point if notifications should be enabled or disabled
 420         dataChangeListeners.add(dataChangeListenerPath);
 421
 422         AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>>
 423             listener = new DataChangeListenerProxy(schemaContext, dataChangeListenerPath);
 424
 425         ListenerRegistration<AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>>>
 426             registration = store.registerChangeListener(registerChangeListener.getPath(),
 427                 listener, registerChangeListener.getScope());
 428         ActorRef listenerRegistration =
 429             getContext().actorOf(
 430                 DataChangeListenerRegistration.props(registration));
 431
 432         LOG.debug(
 433             "registerDataChangeListener sending reply, listenerRegistrationPath = {} "
 434             , listenerRegistration.path().toString());
 435
 436         getSender()
 437             .tell(new RegisterChangeListenerReply(listenerRegistration.path()),
 438                 getSelf());
 439     }
 440
 441     private void createTransactionChain() {
 442         DOMStoreTransactionChain chain = store.createTransactionChain();
 443         ActorRef transactionChain = getContext().actorOf(
 444                 ShardTransactionChain.props(chain, schemaContext, datastoreContext, shardMBean));
 445         getSender().tell(new CreateTransactionChainReply(transactionChain.path()).toSerializable(),
 446                 getSelf());
 447     }
 448
 449     private boolean isMetricsCaptureEnabled(){
 450         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 451         return config.isMetricCaptureEnabled();
 452     }
 453
 454     @Override protected void applyState(ActorRef clientActor, String identifier,
 455         Object data) {
 456
 457         if (data instanceof CompositeModificationPayload) {
 458             Object modification =
 459                 ((CompositeModificationPayload) data).getModification();
 460
 461             if (modification != null) {
 462                 commit(clientActor, modification);
 463             } else {
 464                 LOG.error(
 465                     "modification is null - this is very unexpected, clientActor = {}, identifier = {}",
 466                     identifier, clientActor.path().toString());
 467             }
 468
 469         } else {
 470             LOG.error("Unknown state received {}", data);
 471         }
 472
 473         // Update stats
 474         ReplicatedLogEntry lastLogEntry = getLastLogEntry();
 475
 476         if (lastLogEntry != null) {
 477             shardMBean.setLastLogIndex(lastLogEntry.getIndex());
 478             shardMBean.setLastLogTerm(lastLogEntry.getTerm());
 479         }
 480
 481         shardMBean.setCommitIndex(getCommitIndex());
 482         shardMBean.setLastApplied(getLastApplied());
 483
 484     }
 485
 486     @Override protected void createSnapshot() {
 487         if (createSnapshotTransaction == null) {
 488
 489             // Create a transaction. We are really going to treat the transaction as a worker
 490             // so that this actor does not get block building the snapshot
 491             createSnapshotTransaction = createTransaction(
 492                 TransactionProxy.TransactionType.READ_ONLY.ordinal(),
 493                 "createSnapshot", "");
 494
 495             createSnapshotTransaction.tell(
 496                 new ReadData(YangInstanceIdentifier.builder().build()).toSerializable(), self());
 497
 498         }
 499     }
 500
 501     @VisibleForTesting @Override protected void applySnapshot(ByteString snapshot) {
 502         // Since this will be done only on Recovery or when this actor is a Follower
 503         // we can safely commit everything in here. We not need to worry about event notifications
 504         // as they would have already been disabled on the follower
 505         try {
 506             DOMStoreWriteTransaction transaction = store.newWriteOnlyTransaction();
 507             NormalizedNodeMessages.Node serializedNode = NormalizedNodeMessages.Node.parseFrom(snapshot);
 508             NormalizedNode<?, ?> node = new NormalizedNodeToNodeCodec(schemaContext)
 509                 .decode(YangInstanceIdentifier.builder().build(), serializedNode);
 510
 511             // delete everything first
 512             transaction.delete(YangInstanceIdentifier.builder().build());
 513
 514             // Add everything from the remote node back
 515             transaction.write(YangInstanceIdentifier.builder().build(), node);
 516             syncCommitTransaction(transaction);
 517         } catch (InvalidProtocolBufferException | InterruptedException | ExecutionException e) {
 518             LOG.error(e, "An exception occurred when applying snapshot");
 519         }
 520     }
 521
 522     @Override protected void onStateChanged() {
 523         for (ActorSelection dataChangeListener : dataChangeListeners) {
 524             dataChangeListener
 525                 .tell(new EnableNotification(isLeader()), getSelf());
 526         }
 527
 528         if (getLeaderId() != null) {
 529             shardMBean.setLeader(getLeaderId());
 530         }
 531
 532         shardMBean.setRaftState(getRaftState().name());
 533         shardMBean.setCurrentTerm(getCurrentTerm());
 534
 535         // If this actor is no longer the leader close all the transaction chains
 536         if(!isLeader()){
 537             for(Map.Entry<String, DOMStoreTransactionChain> entry : transactionChains.entrySet()){
 538                 LOG.debug("onStateChanged: Closing transaction chain {} because shard {} is no longer the leader", entry.getKey(), getId());
 539                 entry.getValue().close();
 540             }
 541
 542             transactionChains.clear();
 543         }
 544     }
 545
 546     @Override public String persistenceId() {
 547         return this.name.toString();
 548     }
 549
 550
 551     private static class ShardConfigParams extends DefaultConfigParamsImpl {
 552         public static final FiniteDuration HEART_BEAT_INTERVAL =
 553             new FiniteDuration(500, TimeUnit.MILLISECONDS);
 554
 555         @Override public FiniteDuration getHeartBeatInterval() {
 556             return HEART_BEAT_INTERVAL;
 557         }
 558     }
 559
 560     private static class ShardCreator implements Creator<Shard> {
 561
 562         private static final long serialVersionUID = 1L;
 563
 564         final ShardIdentifier name;
 565         final Map<ShardIdentifier, String> peerAddresses;
 566         final DatastoreContext datastoreContext;
 567         final SchemaContext schemaContext;
 568
 569         ShardCreator(ShardIdentifier name, Map<ShardIdentifier, String> peerAddresses,
 570                 DatastoreContext datastoreContext, SchemaContext schemaContext) {
 571             this.name = name;
 572             this.peerAddresses = peerAddresses;
 573             this.datastoreContext = datastoreContext;
 574             this.schemaContext = schemaContext;
 575         }
 576
 577         @Override
 578         public Shard create() throws Exception {
 579             return new Shard(name, peerAddresses, datastoreContext, schemaContext);
 580         }
 581     }
 582
 583     @VisibleForTesting NormalizedNode readStore() throws ExecutionException, InterruptedException {
 584         DOMStoreReadTransaction transaction = store.newReadOnlyTransaction();
 585
 586         CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> future =
 587             transaction.read(YangInstanceIdentifier.builder().build());
 588
 589         NormalizedNode<?, ?> node = future.get().get();
 590
 591         transaction.close();
 592
 593         return node;
 594     }
 595
 596     @VisibleForTesting void writeToStore(YangInstanceIdentifier id, NormalizedNode node)
 597         throws ExecutionException, InterruptedException {
 598         DOMStoreWriteTransaction transaction = store.newWriteOnlyTransaction();
 599
 600         transaction.write(id, node);
 601
 602         syncCommitTransaction(transaction);
 603     }
 604
 605 }