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.cluster.raft.protobuff.client.messages.CompositeModificationPayload;
  57 import org.opendaylight.controller.md.sal.common.api.data.AsyncDataChangeListener;
  58 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
  59 import org.opendaylight.controller.md.sal.dom.store.impl.InMemoryDOMDataStore;
  60 import org.opendaylight.controller.md.sal.dom.store.impl.InMemoryDOMDataStoreFactory;
  61 import org.opendaylight.controller.protobuff.messages.common.NormalizedNodeMessages;
  62 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadTransaction;
  63 import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
  64 import org.opendaylight.controller.sal.core.spi.data.DOMStoreTransactionChain;
  65 import org.opendaylight.controller.sal.core.spi.data.DOMStoreTransactionFactory;
  66 import org.opendaylight.controller.sal.core.spi.data.DOMStoreWriteTransaction;
  67 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  68 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  69 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  70 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  71 import scala.concurrent.duration.FiniteDuration;
  72
  73 import java.util.ArrayList;
  74 import java.util.HashMap;
  75 import java.util.List;
  76 import java.util.Map;
  77 import java.util.concurrent.ExecutionException;
  78 import java.util.concurrent.TimeUnit;
  79
  80 /**
  81  * A Shard represents a portion of the logical data tree <br/>
  82  * <p>
  83  * Our Shard uses InMemoryDataStore as it's internal representation and delegates all requests it
  84  * </p>
  85  */
  86 public class Shard extends RaftActor {
  87
  88     private static final ConfigParams configParams = new ShardConfigParams();
  89
  90     public static final String DEFAULT_NAME = "default";
  91
  92     // The state of this Shard
  93     private final InMemoryDOMDataStore store;
  94
  95     private final Map<Object, DOMStoreThreePhaseCommitCohort>
  96         modificationToCohort = new HashMap<>();
  97
  98     private final LoggingAdapter LOG =
  99         Logging.getLogger(getContext().system(), this);
 100
 101     // By default persistent will be true and can be turned off using the system
 102     // property shard.persistent
 103     private final boolean persistent;
 104
 105     /// The name of this shard
 106     private final ShardIdentifier name;
 107
 108     private final ShardStats shardMBean;
 109
 110     private final List<ActorSelection> dataChangeListeners = new ArrayList<>();
 111
 112     private final DatastoreContext datastoreContext;
 113
 114     private SchemaContext schemaContext;
 115
 116     private ActorRef createSnapshotTransaction;
 117
 118     private final Map<String, DOMStoreTransactionChain> transactionChains = new HashMap<>();
 119
 120     private Shard(ShardIdentifier name, Map<ShardIdentifier, String> peerAddresses,
 121             DatastoreContext datastoreContext, SchemaContext schemaContext) {
 122         super(name.toString(), mapPeerAddresses(peerAddresses), Optional.of(configParams));
 123
 124         this.name = name;
 125         this.datastoreContext = datastoreContext;
 126         this.schemaContext = schemaContext;
 127
 128         String setting = System.getProperty("shard.persistent");
 129
 130         this.persistent = !"false".equals(setting);
 131
 132         LOG.info("Shard created : {} persistent : {}", name, persistent);
 133
 134         store = InMemoryDOMDataStoreFactory.create(name.toString(), null,
 135                 datastoreContext.getDataStoreProperties());
 136
 137         if(schemaContext != null) {
 138             store.onGlobalContextUpdated(schemaContext);
 139         }
 140
 141         shardMBean = ShardMBeanFactory.getShardStatsMBean(name.toString(),
 142                 datastoreContext.getDataStoreMXBeanType());
 143         shardMBean.setDataStoreExecutor(store.getDomStoreExecutor());
 144         shardMBean.setNotificationManager(store.getDataChangeListenerNotificationManager());
 145
 146         if (isMetricsCaptureEnabled()) {
 147             getContext().become(new MeteringBehavior(this));
 148         }
 149     }
 150
 151     private static Map<String, String> mapPeerAddresses(
 152         Map<ShardIdentifier, String> peerAddresses) {
 153         Map<String, String> map = new HashMap<>();
 154
 155         for (Map.Entry<ShardIdentifier, String> entry : peerAddresses
 156             .entrySet()) {
 157             map.put(entry.getKey().toString(), entry.getValue());
 158         }
 159
 160         return map;
 161     }
 162
 163     public static Props props(final ShardIdentifier name,
 164         final Map<ShardIdentifier, String> peerAddresses,
 165         DatastoreContext datastoreContext, SchemaContext schemaContext) {
 166         Preconditions.checkNotNull(name, "name should not be null");
 167         Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
 168         Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
 169         Preconditions.checkNotNull(schemaContext, "schemaContext should not be null");
 170
 171         return Props.create(new ShardCreator(name, peerAddresses, datastoreContext, schemaContext));
 172     }
 173
 174     @Override public void onReceiveRecover(Object message) {
 175         LOG.debug("onReceiveRecover: Received message {} from {}", message.getClass().toString(),
 176             getSender());
 177
 178         if (message instanceof RecoveryFailure){
 179             LOG.error(((RecoveryFailure) message).cause(), "Recovery failed because of this cause");
 180         } else {
 181             super.onReceiveRecover(message);
 182         }
 183     }
 184
 185     @Override public void onReceiveCommand(Object message) {
 186         LOG.debug("onReceiveCommand: Received message {} from {}", message.getClass().toString(),
 187             getSender());
 188
 189         if(message.getClass().equals(ReadDataReply.SERIALIZABLE_CLASS)) {
 190             // This must be for install snapshot. Don't want to open this up and trigger
 191             // deSerialization
 192             self()
 193                 .tell(new CaptureSnapshotReply(ReadDataReply.getNormalizedNodeByteString(message)),
 194                     self());
 195
 196             createSnapshotTransaction = null;
 197             // Send a PoisonPill instead of sending close transaction because we do not really need
 198             // a response
 199             getSender().tell(PoisonPill.getInstance(), self());
 200
 201         } else if (message.getClass().equals(CloseTransactionChain.SERIALIZABLE_CLASS)){
 202             closeTransactionChain(CloseTransactionChain.fromSerializable(message));
 203         } else if (message instanceof RegisterChangeListener) {
 204             registerChangeListener((RegisterChangeListener) message);
 205         } else if (message instanceof UpdateSchemaContext) {
 206             updateSchemaContext((UpdateSchemaContext) message);
 207         } else if (message instanceof ForwardedCommitTransaction) {
 208             handleForwardedCommit((ForwardedCommitTransaction) message);
 209         } else if (message.getClass()
 210             .equals(CreateTransaction.SERIALIZABLE_CLASS)) {
 211             if (isLeader()) {
 212                 createTransaction(CreateTransaction.fromSerializable(message));
 213             } else if (getLeader() != null) {
 214                 getLeader().forward(message, getContext());
 215             } else {
 216                 getSender().tell(new akka.actor.Status.Failure(new IllegalStateException(
 217                     "Could not find leader so transaction cannot be created")), getSelf());
 218             }
 219         } else if (message instanceof PeerAddressResolved) {
 220             PeerAddressResolved resolved = (PeerAddressResolved) message;
 221             setPeerAddress(resolved.getPeerId().toString(),
 222                 resolved.getPeerAddress());
 223         } else {
 224             super.onReceiveCommand(message);
 225         }
 226     }
 227
 228     private void closeTransactionChain(CloseTransactionChain closeTransactionChain) {
 229         DOMStoreTransactionChain chain =
 230             transactionChains.remove(closeTransactionChain.getTransactionChainId());
 231
 232         if(chain != null) {
 233             chain.close();
 234         }
 235     }
 236
 237     private ActorRef createTypedTransactionActor(
 238         int transactionType,
 239         ShardTransactionIdentifier transactionId,
 240         String transactionChainId ) {
 241
 242         DOMStoreTransactionFactory factory = store;
 243
 244         if(!transactionChainId.isEmpty()) {
 245             factory = transactionChains.get(transactionChainId);
 246             if(factory == null){
 247                 DOMStoreTransactionChain transactionChain = store.createTransactionChain();
 248                 transactionChains.put(transactionChainId, transactionChain);
 249                 factory = transactionChain;
 250             }
 251         }
 252
 253         if(this.schemaContext == null){
 254             throw new NullPointerException("schemaContext should not be null");
 255         }
 256
 257         if (transactionType
 258             == TransactionProxy.TransactionType.READ_ONLY.ordinal()) {
 259
 260             shardMBean.incrementReadOnlyTransactionCount();
 261
 262             return getContext().actorOf(
 263                 ShardTransaction.props(factory.newReadOnlyTransaction(), getSelf(),
 264                         schemaContext,datastoreContext, shardMBean), transactionId.toString());
 265
 266         } else if (transactionType
 267             == TransactionProxy.TransactionType.READ_WRITE.ordinal()) {
 268
 269             shardMBean.incrementReadWriteTransactionCount();
 270
 271             return getContext().actorOf(
 272                 ShardTransaction.props(factory.newReadWriteTransaction(), getSelf(),
 273                         schemaContext, datastoreContext, shardMBean), transactionId.toString());
 274
 275
 276         } else if (transactionType
 277             == TransactionProxy.TransactionType.WRITE_ONLY.ordinal()) {
 278
 279             shardMBean.incrementWriteOnlyTransactionCount();
 280
 281             return getContext().actorOf(
 282                 ShardTransaction.props(factory.newWriteOnlyTransaction(), getSelf(),
 283                         schemaContext, datastoreContext, shardMBean), transactionId.toString());
 284         } else {
 285             throw new IllegalArgumentException(
 286                 "Shard="+name + ":CreateTransaction message has unidentified transaction type="
 287                     + transactionType);
 288         }
 289     }
 290
 291     private void createTransaction(CreateTransaction createTransaction) {
 292         createTransaction(createTransaction.getTransactionType(),
 293             createTransaction.getTransactionId(), createTransaction.getTransactionChainId());
 294     }
 295
 296     private ActorRef createTransaction(int transactionType, String remoteTransactionId, String transactionChainId) {
 297
 298         ShardTransactionIdentifier transactionId =
 299             ShardTransactionIdentifier.builder()
 300                 .remoteTransactionId(remoteTransactionId)
 301                 .build();
 302         LOG.debug("Creating transaction : {} ", transactionId);
 303         ActorRef transactionActor =
 304             createTypedTransactionActor(transactionType, transactionId, transactionChainId);
 305
 306         getSender()
 307             .tell(new CreateTransactionReply(
 308                     Serialization.serializedActorPath(transactionActor),
 309                     remoteTransactionId).toSerializable(),
 310                 getSelf());
 311
 312         return transactionActor;
 313     }
 314
 315     private void syncCommitTransaction(DOMStoreWriteTransaction transaction)
 316         throws ExecutionException, InterruptedException {
 317         DOMStoreThreePhaseCommitCohort commitCohort = transaction.ready();
 318         commitCohort.preCommit().get();
 319         commitCohort.commit().get();
 320     }
 321
 322
 323     private void commit(final ActorRef sender, Object serialized) {
 324         Modification modification = MutableCompositeModification
 325             .fromSerializable(serialized, schemaContext);
 326         DOMStoreThreePhaseCommitCohort cohort =
 327             modificationToCohort.remove(serialized);
 328         if (cohort == null) {
 329             LOG.debug(
 330                 "Could not find cohort for modification : {}. Writing modification using a new transaction",
 331                 modification);
 332             DOMStoreWriteTransaction transaction =
 333                 store.newWriteOnlyTransaction();
 334
 335             LOG.debug("Created new transaction {}", transaction.getIdentifier().toString());
 336
 337             modification.apply(transaction);
 338             try {
 339                 syncCommitTransaction(transaction);
 340             } catch (InterruptedException | ExecutionException e) {
 341                 shardMBean.incrementFailedTransactionsCount();
 342                 LOG.error("Failed to commit", e);
 343                 return;
 344             }
 345             //we want to just apply the recovery commit and return
 346             shardMBean.incrementCommittedTransactionCount();
 347             return;
 348         }
 349
 350
 351         if(sender == null){
 352             LOG.error("Commit failed. Sender cannot be null");
 353             return;
 354         }
 355
 356         final ListenableFuture<Void> future = cohort.commit();
 357         final ActorRef self = getSelf();
 358
 359         Futures.addCallback(future, new FutureCallback<Void>() {
 360             @Override
 361             public void onSuccess(Void v) {
 362                 sender.tell(new CommitTransactionReply().toSerializable(), self);
 363                 shardMBean.incrementCommittedTransactionCount();
 364                 shardMBean.setLastCommittedTransactionTime(System.currentTimeMillis());
 365             }
 366
 367             @Override
 368             public void onFailure(Throwable t) {
 369                 LOG.error(t, "An exception happened during commit");
 370                 shardMBean.incrementFailedTransactionsCount();
 371                 sender.tell(new akka.actor.Status.Failure(t), self);
 372             }
 373         });
 374
 375     }
 376
 377     private void handleForwardedCommit(ForwardedCommitTransaction message) {
 378         Object serializedModification =
 379             message.getModification().toSerializable();
 380
 381         modificationToCohort
 382             .put(serializedModification, message.getCohort());
 383
 384         if (persistent) {
 385             this.persistData(getSender(), "identifier",
 386                 new CompositeModificationPayload(serializedModification));
 387         } else {
 388             this.commit(getSender(), serializedModification);
 389         }
 390     }
 391
 392     private void updateSchemaContext(UpdateSchemaContext message) {
 393         this.schemaContext = message.getSchemaContext();
 394         updateSchemaContext(message.getSchemaContext());
 395         store.onGlobalContextUpdated(message.getSchemaContext());
 396     }
 397
 398     @VisibleForTesting void updateSchemaContext(SchemaContext schemaContext) {
 399         store.onGlobalContextUpdated(schemaContext);
 400     }
 401
 402     private void registerChangeListener(
 403         RegisterChangeListener registerChangeListener) {
 404
 405         LOG.debug("registerDataChangeListener for {}", registerChangeListener
 406             .getPath());
 407
 408
 409         ActorSelection dataChangeListenerPath = getContext()
 410             .system().actorSelection(
 411                 registerChangeListener.getDataChangeListenerPath());
 412
 413
 414         // Notify the listener if notifications should be enabled or not
 415         // If this shard is the leader then it will enable notifications else
 416         // it will not
 417         dataChangeListenerPath
 418             .tell(new EnableNotification(isLeader()), getSelf());
 419
 420         // Now store a reference to the data change listener so it can be notified
 421         // at a later point if notifications should be enabled or disabled
 422         dataChangeListeners.add(dataChangeListenerPath);
 423
 424         AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>>
 425             listener = new DataChangeListenerProxy(schemaContext, dataChangeListenerPath);
 426
 427         ListenerRegistration<AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>>>
 428             registration = store.registerChangeListener(registerChangeListener.getPath(),
 429                 listener, registerChangeListener.getScope());
 430         ActorRef listenerRegistration =
 431             getContext().actorOf(
 432                 DataChangeListenerRegistration.props(registration));
 433
 434         LOG.debug(
 435             "registerDataChangeListener sending reply, listenerRegistrationPath = {} "
 436             , listenerRegistration.path().toString());
 437
 438         getSender()
 439             .tell(new RegisterChangeListenerReply(listenerRegistration.path()),
 440                 getSelf());
 441     }
 442
 443     private void createTransactionChain() {
 444         DOMStoreTransactionChain chain = store.createTransactionChain();
 445         ActorRef transactionChain = getContext().actorOf(
 446                 ShardTransactionChain.props(chain, schemaContext, datastoreContext, shardMBean));
 447         getSender().tell(new CreateTransactionChainReply(transactionChain.path()).toSerializable(),
 448                 getSelf());
 449     }
 450
 451     private boolean isMetricsCaptureEnabled(){
 452         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 453         return config.isMetricCaptureEnabled();
 454     }
 455
 456     @Override protected void applyState(ActorRef clientActor, String identifier,
 457         Object data) {
 458
 459         if (data instanceof CompositeModificationPayload) {
 460             Object modification =
 461                 ((CompositeModificationPayload) data).getModification();
 462
 463             if (modification != null) {
 464                 commit(clientActor, modification);
 465             } else {
 466                 LOG.error(
 467                     "modification is null - this is very unexpected, clientActor = {}, identifier = {}",
 468                     identifier, clientActor.path().toString());
 469             }
 470
 471         } else {
 472             LOG.error("Unknown state received {} Class loader = {} CompositeNodeMod.ClassLoader = {}", data, data.getClass().getClassLoader(), CompositeModificationPayload.class.getClassLoader());
 473         }
 474
 475         // Update stats
 476         ReplicatedLogEntry lastLogEntry = getLastLogEntry();
 477
 478         if (lastLogEntry != null) {
 479             shardMBean.setLastLogIndex(lastLogEntry.getIndex());
 480             shardMBean.setLastLogTerm(lastLogEntry.getTerm());
 481         }
 482
 483         shardMBean.setCommitIndex(getCommitIndex());
 484         shardMBean.setLastApplied(getLastApplied());
 485
 486     }
 487
 488     @Override protected void createSnapshot() {
 489         if (createSnapshotTransaction == null) {
 490
 491             // Create a transaction. We are really going to treat the transaction as a worker
 492             // so that this actor does not get block building the snapshot
 493             createSnapshotTransaction = createTransaction(
 494                 TransactionProxy.TransactionType.READ_ONLY.ordinal(),
 495                 "createSnapshot", "");
 496
 497             createSnapshotTransaction.tell(
 498                 new ReadData(YangInstanceIdentifier.builder().build()).toSerializable(), self());
 499
 500         }
 501     }
 502
 503     @VisibleForTesting @Override protected void applySnapshot(ByteString snapshot) {
 504         // Since this will be done only on Recovery or when this actor is a Follower
 505         // we can safely commit everything in here. We not need to worry about event notifications
 506         // as they would have already been disabled on the follower
 507
 508         LOG.info("Applying snapshot");
 509         try {
 510             DOMStoreWriteTransaction transaction = store.newWriteOnlyTransaction();
 511             NormalizedNodeMessages.Node serializedNode = NormalizedNodeMessages.Node.parseFrom(snapshot);
 512             NormalizedNode<?, ?> node = new NormalizedNodeToNodeCodec(schemaContext)
 513                 .decode(YangInstanceIdentifier.builder().build(), serializedNode);
 514
 515             // delete everything first
 516             transaction.delete(YangInstanceIdentifier.builder().build());
 517
 518             // Add everything from the remote node back
 519             transaction.write(YangInstanceIdentifier.builder().build(), node);
 520             syncCommitTransaction(transaction);
 521         } catch (InvalidProtocolBufferException | InterruptedException | ExecutionException e) {
 522             LOG.error(e, "An exception occurred when applying snapshot");
 523         } finally {
 524             LOG.info("Done applying snapshot");
 525         }
 526     }
 527
 528     @Override protected void onStateChanged() {
 529         for (ActorSelection dataChangeListener : dataChangeListeners) {
 530             dataChangeListener
 531                 .tell(new EnableNotification(isLeader()), getSelf());
 532         }
 533
 534
 535         shardMBean.setRaftState(getRaftState().name());
 536         shardMBean.setCurrentTerm(getCurrentTerm());
 537
 538         // If this actor is no longer the leader close all the transaction chains
 539         if(!isLeader()){
 540             for(Map.Entry<String, DOMStoreTransactionChain> entry : transactionChains.entrySet()){
 541                 LOG.debug("onStateChanged: Closing transaction chain {} because shard {} is no longer the leader", entry.getKey(), getId());
 542                 entry.getValue().close();
 543             }
 544
 545             transactionChains.clear();
 546         }
 547     }
 548
 549     @Override protected void onLeaderChanged(String oldLeader, String newLeader) {
 550         shardMBean.setLeader(newLeader);
 551     }
 552
 553     @Override public String persistenceId() {
 554         return this.name.toString();
 555     }
 556
 557
 558     private static class ShardConfigParams extends DefaultConfigParamsImpl {
 559         public static final FiniteDuration HEART_BEAT_INTERVAL =
 560             new FiniteDuration(500, TimeUnit.MILLISECONDS);
 561
 562         @Override public FiniteDuration getHeartBeatInterval() {
 563             return HEART_BEAT_INTERVAL;
 564         }
 565     }
 566
 567     private static class ShardCreator implements Creator<Shard> {
 568
 569         private static final long serialVersionUID = 1L;
 570
 571         final ShardIdentifier name;
 572         final Map<ShardIdentifier, String> peerAddresses;
 573         final DatastoreContext datastoreContext;
 574         final SchemaContext schemaContext;
 575
 576         ShardCreator(ShardIdentifier name, Map<ShardIdentifier, String> peerAddresses,
 577                 DatastoreContext datastoreContext, SchemaContext schemaContext) {
 578             this.name = name;
 579             this.peerAddresses = peerAddresses;
 580             this.datastoreContext = datastoreContext;
 581             this.schemaContext = schemaContext;
 582         }
 583
 584         @Override
 585         public Shard create() throws Exception {
 586             return new Shard(name, peerAddresses, datastoreContext, schemaContext);
 587         }
 588     }
 589
 590     @VisibleForTesting NormalizedNode readStore() throws ExecutionException, InterruptedException {
 591         DOMStoreReadTransaction transaction = store.newReadOnlyTransaction();
 592
 593         CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> future =
 594             transaction.read(YangInstanceIdentifier.builder().build());
 595
 596         NormalizedNode<?, ?> node = future.get().get();
 597
 598         transaction.close();
 599
 600         return node;
 601     }
 602
 603     @VisibleForTesting void writeToStore(YangInstanceIdentifier id, NormalizedNode node)
 604         throws ExecutionException, InterruptedException {
 605         DOMStoreWriteTransaction transaction = store.newWriteOnlyTransaction();
 606
 607         transaction.write(id, node);
 608
 609         syncCommitTransaction(transaction);
 610     }
 611
 612 }