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.Cancellable;
  14 import akka.actor.ExtendedActorSystem;
  15 import akka.actor.Props;
  16 import akka.actor.Status;
  17 import akka.actor.Status.Failure;
  18 import akka.serialization.JavaSerializer;
  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.base.Ticker;
  24 import com.google.common.base.Verify;
  25 import com.google.common.collect.ImmutableList;
  26 import com.google.common.collect.ImmutableMap;
  27 import com.google.common.collect.Range;
  28 import java.io.IOException;
  29 import java.util.Arrays;
  30 import java.util.Collection;
  31 import java.util.Collections;
  32 import java.util.Map;
  33 import java.util.concurrent.TimeUnit;
  34 import javax.annotation.Nonnull;
  35 import javax.annotation.Nullable;
  36 import org.opendaylight.controller.cluster.access.ABIVersion;
  37 import org.opendaylight.controller.cluster.access.commands.ConnectClientRequest;
  38 import org.opendaylight.controller.cluster.access.commands.ConnectClientSuccess;
  39 import org.opendaylight.controller.cluster.access.commands.LocalHistoryRequest;
  40 import org.opendaylight.controller.cluster.access.commands.NotLeaderException;
  41 import org.opendaylight.controller.cluster.access.commands.OutOfSequenceEnvelopeException;
  42 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
  43 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  44 import org.opendaylight.controller.cluster.access.concepts.FrontendIdentifier;
  45 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
  46 import org.opendaylight.controller.cluster.access.concepts.Request;
  47 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
  48 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  49 import org.opendaylight.controller.cluster.access.concepts.RequestSuccess;
  50 import org.opendaylight.controller.cluster.access.concepts.RetiredGenerationException;
  51 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
  52 import org.opendaylight.controller.cluster.access.concepts.SliceableMessage;
  53 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  54 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
  55 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
  56 import org.opendaylight.controller.cluster.common.actor.Dispatchers;
  57 import org.opendaylight.controller.cluster.common.actor.Dispatchers.DispatcherType;
  58 import org.opendaylight.controller.cluster.common.actor.MessageTracker;
  59 import org.opendaylight.controller.cluster.common.actor.MessageTracker.Error;
  60 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
  61 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  62 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  63 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardDataTreeListenerInfoMXBeanImpl;
  64 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardMBeanFactory;
  65 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
  66 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
  67 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
  68 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  69 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransaction;
  70 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  71 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
  72 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  73 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  74 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
  75 import org.opendaylight.controller.cluster.datastore.messages.GetShardDataTree;
  76 import org.opendaylight.controller.cluster.datastore.messages.MakeLeaderLocal;
  77 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
  78 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
  79 import org.opendaylight.controller.cluster.datastore.messages.PersistAbortTransactionPayload;
  80 import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
  81 import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
  82 import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
  83 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
  84 import org.opendaylight.controller.cluster.datastore.persisted.AbortTransactionPayload;
  85 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot;
  86 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot.ShardSnapshot;
  87 import org.opendaylight.controller.cluster.messaging.MessageAssembler;
  88 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
  89 import org.opendaylight.controller.cluster.messaging.SliceOptions;
  90 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
  91 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
  92 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
  93 import org.opendaylight.controller.cluster.raft.LeadershipTransferFailedException;
  94 import org.opendaylight.controller.cluster.raft.RaftActor;
  95 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
  96 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
  97 import org.opendaylight.controller.cluster.raft.RaftState;
  98 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
  99 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
 100 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
 101 import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
 102 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
 103 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
 104 import org.opendaylight.yangtools.concepts.Identifier;
 105 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
 106 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
 107 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
 108 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
 109 import org.opendaylight.yangtools.yang.model.api.SchemaContextProvider;
 110 import scala.concurrent.duration.Duration;
 111 import scala.concurrent.duration.FiniteDuration;
 112
 113 /**
 114  * A Shard represents a portion of the logical data tree.
 115  *
 116  * <p>
 117  * Our Shard uses InMemoryDataTree as it's internal representation and delegates all requests it
 118  */
 119 public class Shard extends RaftActor {
 120
 121     @VisibleForTesting
 122     static final Object TX_COMMIT_TIMEOUT_CHECK_MESSAGE = new Object() {
 123         @Override
 124         public String toString() {
 125             return "txCommitTimeoutCheck";
 126         }
 127     };
 128
 129     @VisibleForTesting
 130     static final Object GET_SHARD_MBEAN_MESSAGE = new Object() {
 131         @Override
 132         public String toString() {
 133             return "getShardMBeanMessage";
 134         }
 135     };
 136
 137     static final Object RESUME_NEXT_PENDING_TRANSACTION = new Object() {
 138         @Override
 139         public String toString() {
 140             return "resumeNextPendingTransaction";
 141         }
 142     };
 143
 144     // FIXME: shard names should be encapsulated in their own class and this should be exposed as a constant.
 145     public static final String DEFAULT_NAME = "default";
 146
 147     private static final Collection<ABIVersion> SUPPORTED_ABIVERSIONS;
 148
 149     static {
 150         final ABIVersion[] values = ABIVersion.values();
 151         final ABIVersion[] real = Arrays.copyOfRange(values, 1, values.length - 1);
 152         SUPPORTED_ABIVERSIONS = ImmutableList.copyOf(real).reverse();
 153     }
 154
 155     // FIXME: make this a dynamic property based on mailbox size and maximum number of clients
 156     private static final int CLIENT_MAX_MESSAGES = 1000;
 157
 158     // The state of this Shard
 159     private final ShardDataTree store;
 160
 161     /// The name of this shard
 162     private final String name;
 163
 164     private final String shardName;
 165
 166     private final ShardStats shardMBean;
 167
 168     private final ShardDataTreeListenerInfoMXBeanImpl listenerInfoMXBean;
 169
 170     private DatastoreContext datastoreContext;
 171
 172     private final ShardCommitCoordinator commitCoordinator;
 173
 174     private long transactionCommitTimeout;
 175
 176     private Cancellable txCommitTimeoutCheckSchedule;
 177
 178     private final Optional<ActorRef> roleChangeNotifier;
 179
 180     private final MessageTracker appendEntriesReplyTracker;
 181
 182     private final ShardTransactionActorFactory transactionActorFactory;
 183
 184     private final ShardSnapshotCohort snapshotCohort;
 185
 186     private final DataTreeChangeListenerSupport treeChangeSupport = new DataTreeChangeListenerSupport(this);
 187
 188     private ShardSnapshot restoreFromSnapshot;
 189
 190     private final ShardTransactionMessageRetrySupport messageRetrySupport;
 191
 192     private final FrontendMetadata frontendMetadata;
 193     private Map<FrontendIdentifier, LeaderFrontendState> knownFrontends = ImmutableMap.of();
 194     private boolean paused;
 195
 196     private final MessageSlicer responseMessageSlicer;
 197     private final Dispatchers dispatchers;
 198
 199     private final MessageAssembler requestMessageAssembler;
 200
 201     protected Shard(final AbstractBuilder<?, ?> builder) {
 202         super(builder.getId().toString(), builder.getPeerAddresses(),
 203                 Optional.of(builder.getDatastoreContext().getShardRaftConfig()), DataStoreVersions.CURRENT_VERSION);
 204
 205         this.name = builder.getId().toString();
 206         this.shardName = builder.getId().getShardName();
 207         this.datastoreContext = builder.getDatastoreContext();
 208         this.restoreFromSnapshot = builder.getRestoreFromSnapshot();
 209         this.frontendMetadata = new FrontendMetadata(name);
 210
 211         setPersistence(datastoreContext.isPersistent());
 212
 213         LOG.info("Shard created : {}, persistent : {}", name, datastoreContext.isPersistent());
 214
 215         ShardDataTreeChangeListenerPublisherActorProxy treeChangeListenerPublisher =
 216                 new ShardDataTreeChangeListenerPublisherActorProxy(getContext(), name + "-DTCL-publisher", name);
 217         if (builder.getDataTree() != null) {
 218             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getDataTree(),
 219                     treeChangeListenerPublisher, name, frontendMetadata);
 220         } else {
 221             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getTreeType(),
 222                     builder.getDatastoreContext().getStoreRoot(), treeChangeListenerPublisher, name, frontendMetadata);
 223         }
 224
 225         shardMBean = ShardMBeanFactory.getShardStatsMBean(name, datastoreContext.getDataStoreMXBeanType(), this);
 226
 227         if (isMetricsCaptureEnabled()) {
 228             getContext().become(new MeteringBehavior(this));
 229         }
 230
 231         commitCoordinator = new ShardCommitCoordinator(store, LOG, this.name);
 232
 233         setTransactionCommitTimeout();
 234
 235         // create a notifier actor for each cluster member
 236         roleChangeNotifier = createRoleChangeNotifier(name);
 237
 238         appendEntriesReplyTracker = new MessageTracker(AppendEntriesReply.class,
 239                 getRaftActorContext().getConfigParams().getIsolatedCheckIntervalInMillis());
 240
 241         dispatchers = new Dispatchers(context().system().dispatchers());
 242         transactionActorFactory = new ShardTransactionActorFactory(store, datastoreContext,
 243             dispatchers.getDispatcherPath(Dispatchers.DispatcherType.Transaction),
 244                 self(), getContext(), shardMBean, builder.getId().getShardName());
 245
 246         snapshotCohort = ShardSnapshotCohort.create(getContext(), builder.getId().getMemberName(), store, LOG,
 247             this.name);
 248
 249         messageRetrySupport = new ShardTransactionMessageRetrySupport(this);
 250
 251         responseMessageSlicer = MessageSlicer.builder().logContext(this.name)
 252                 .messageSliceSize(datastoreContext.getMaximumMessageSliceSize())
 253                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 254                 .expireStateAfterInactivity(2, TimeUnit.MINUTES).build();
 255
 256         requestMessageAssembler = MessageAssembler.builder().logContext(this.name)
 257                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 258                 .assembledMessageCallback((message, sender) -> self().tell(message, sender))
 259                 .expireStateAfterInactivity(datastoreContext.getRequestTimeout(), TimeUnit.NANOSECONDS).build();
 260
 261         listenerInfoMXBean = new ShardDataTreeListenerInfoMXBeanImpl(name, datastoreContext.getDataStoreMXBeanType(),
 262                 self());
 263         listenerInfoMXBean.register();
 264     }
 265
 266     private void setTransactionCommitTimeout() {
 267         transactionCommitTimeout = TimeUnit.MILLISECONDS.convert(
 268                 datastoreContext.getShardTransactionCommitTimeoutInSeconds(), TimeUnit.SECONDS) / 2;
 269     }
 270
 271     private Optional<ActorRef> createRoleChangeNotifier(final String shardId) {
 272         ActorRef shardRoleChangeNotifier = this.getContext().actorOf(
 273             RoleChangeNotifier.getProps(shardId), shardId + "-notifier");
 274         return Optional.of(shardRoleChangeNotifier);
 275     }
 276
 277     @Override
 278     public void postStop() {
 279         LOG.info("Stopping Shard {}", persistenceId());
 280
 281         super.postStop();
 282
 283         messageRetrySupport.close();
 284
 285         if (txCommitTimeoutCheckSchedule != null) {
 286             txCommitTimeoutCheckSchedule.cancel();
 287         }
 288
 289         commitCoordinator.abortPendingTransactions("Transaction aborted due to shutdown.", this);
 290
 291         shardMBean.unregisterMBean();
 292         listenerInfoMXBean.unregister();
 293     }
 294
 295     @Override
 296     protected void handleRecover(final Object message) {
 297         LOG.debug("{}: onReceiveRecover: Received message {} from {}", persistenceId(), message.getClass(),
 298             getSender());
 299
 300         super.handleRecover(message);
 301         if (LOG.isTraceEnabled()) {
 302             appendEntriesReplyTracker.begin();
 303         }
 304     }
 305
 306     @Override
 307     protected void handleNonRaftCommand(final Object message) {
 308         try (MessageTracker.Context context = appendEntriesReplyTracker.received(message)) {
 309             final Optional<Error> maybeError = context.error();
 310             if (maybeError.isPresent()) {
 311                 LOG.trace("{} : AppendEntriesReply failed to arrive at the expected interval {}", persistenceId(),
 312                     maybeError.get());
 313             }
 314
 315             store.resetTransactionBatch();
 316
 317             if (message instanceof RequestEnvelope) {
 318                 handleRequestEnvelope((RequestEnvelope)message);
 319             } else if (MessageAssembler.isHandledMessage(message)) {
 320                 handleRequestAssemblerMessage(message);
 321             } else if (message instanceof ConnectClientRequest) {
 322                 handleConnectClient((ConnectClientRequest)message);
 323             } else if (CreateTransaction.isSerializedType(message)) {
 324                 handleCreateTransaction(message);
 325             } else if (message instanceof BatchedModifications) {
 326                 handleBatchedModifications((BatchedModifications)message);
 327             } else if (message instanceof ForwardedReadyTransaction) {
 328                 handleForwardedReadyTransaction((ForwardedReadyTransaction) message);
 329             } else if (message instanceof ReadyLocalTransaction) {
 330                 handleReadyLocalTransaction((ReadyLocalTransaction)message);
 331             } else if (CanCommitTransaction.isSerializedType(message)) {
 332                 handleCanCommitTransaction(CanCommitTransaction.fromSerializable(message));
 333             } else if (CommitTransaction.isSerializedType(message)) {
 334                 handleCommitTransaction(CommitTransaction.fromSerializable(message));
 335             } else if (AbortTransaction.isSerializedType(message)) {
 336                 handleAbortTransaction(AbortTransaction.fromSerializable(message));
 337             } else if (CloseTransactionChain.isSerializedType(message)) {
 338                 closeTransactionChain(CloseTransactionChain.fromSerializable(message));
 339             } else if (message instanceof RegisterDataTreeChangeListener) {
 340                 treeChangeSupport.onMessage((RegisterDataTreeChangeListener) message, isLeader(), hasLeader());
 341             } else if (message instanceof UpdateSchemaContext) {
 342                 updateSchemaContext((UpdateSchemaContext) message);
 343             } else if (message instanceof PeerAddressResolved) {
 344                 PeerAddressResolved resolved = (PeerAddressResolved) message;
 345                 setPeerAddress(resolved.getPeerId(), resolved.getPeerAddress());
 346             } else if (TX_COMMIT_TIMEOUT_CHECK_MESSAGE.equals(message)) {
 347                 commitTimeoutCheck();
 348             } else if (message instanceof DatastoreContext) {
 349                 onDatastoreContext((DatastoreContext)message);
 350             } else if (message instanceof RegisterRoleChangeListener) {
 351                 roleChangeNotifier.get().forward(message, context());
 352             } else if (message instanceof FollowerInitialSyncUpStatus) {
 353                 shardMBean.setFollowerInitialSyncStatus(((FollowerInitialSyncUpStatus) message).isInitialSyncDone());
 354                 context().parent().tell(message, self());
 355             } else if (GET_SHARD_MBEAN_MESSAGE.equals(message)) {
 356                 sender().tell(getShardMBean(), self());
 357             } else if (message instanceof GetShardDataTree) {
 358                 sender().tell(store.getDataTree(), self());
 359             } else if (message instanceof ServerRemoved) {
 360                 context().parent().forward(message, context());
 361             } else if (ShardTransactionMessageRetrySupport.TIMER_MESSAGE_CLASS.isInstance(message)) {
 362                 messageRetrySupport.onTimerMessage(message);
 363             } else if (message instanceof DataTreeCohortActorRegistry.CohortRegistryCommand) {
 364                 store.processCohortRegistryCommand(getSender(),
 365                         (DataTreeCohortActorRegistry.CohortRegistryCommand) message);
 366             } else if (message instanceof PersistAbortTransactionPayload) {
 367                 final TransactionIdentifier txId = ((PersistAbortTransactionPayload) message).getTransactionId();
 368                 persistPayload(txId, AbortTransactionPayload.create(txId), true);
 369             } else if (message instanceof MakeLeaderLocal) {
 370                 onMakeLeaderLocal();
 371             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
 372                 store.resumeNextPendingTransaction();
 373             } else if (!responseMessageSlicer.handleMessage(message)) {
 374                 super.handleNonRaftCommand(message);
 375             }
 376         }
 377     }
 378
 379     private void handleRequestAssemblerMessage(final Object message) {
 380         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
 381             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
 382             requestMessageAssembler.handleMessage(message, self());
 383         });
 384     }
 385
 386     @SuppressWarnings("checkstyle:IllegalCatch")
 387     private void handleRequestEnvelope(final RequestEnvelope envelope) {
 388         final long now = ticker().read();
 389         try {
 390             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
 391             if (success != null) {
 392                 final long executionTimeNanos = ticker().read() - now;
 393                 if (success instanceof SliceableMessage) {
 394                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
 395                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
 396                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
 397                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
 398                             .onFailureCallback(t -> {
 399                                 LOG.warn("Error slicing response {}", success, t);
 400                             }).build()));
 401                 } else {
 402                     envelope.sendSuccess(success, executionTimeNanos);
 403                 }
 404             }
 405         } catch (RequestException e) {
 406             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
 407             envelope.sendFailure(e, ticker().read() - now);
 408         } catch (Exception e) {
 409             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
 410             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
 411                 ticker().read() - now);
 412         }
 413     }
 414
 415     private void commitTimeoutCheck() {
 416         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
 417         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
 418         requestMessageAssembler.checkExpiredAssembledMessageState();
 419     }
 420
 421     private Optional<Long> updateAccess(final SimpleShardDataTreeCohort cohort) {
 422         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
 423         final LeaderFrontendState state = knownFrontends.get(frontend);
 424         if (state == null) {
 425             // Not tell-based protocol, do nothing
 426             return Optional.absent();
 427         }
 428
 429         if (isIsolatedLeader()) {
 430             // We are isolated and no new request can come through until we emerge from it. We are still updating
 431             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
 432             return Optional.of(state.getLastSeenTicks());
 433         }
 434
 435         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
 436         return Optional.of(state.getLastConnectTicks());
 437     }
 438
 439     private void onMakeLeaderLocal() {
 440         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
 441         if (isLeader()) {
 442             getSender().tell(new Status.Success(null), getSelf());
 443             return;
 444         }
 445
 446         final ActorSelection leader = getLeader();
 447
 448         if (leader == null) {
 449             // Leader is not present. The cluster is most likely trying to
 450             // elect a leader and we should let that run its normal course
 451
 452             // TODO we can wait for the election to complete and retry the
 453             // request. We can also let the caller retry by sending a flag
 454             // in the response indicating the request is "reTryable".
 455             getSender().tell(new Failure(
 456                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
 457                             + "Currently there is no leader for " + persistenceId())),
 458                     getSelf());
 459             return;
 460         }
 461
 462         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
 463     }
 464
 465     // Acquire our frontend tracking handle and verify generation matches
 466     @Nullable
 467     private LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
 468         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
 469         if (existing != null) {
 470             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
 471             if (cmp == 0) {
 472                 existing.touch();
 473                 return existing;
 474             }
 475             if (cmp > 0) {
 476                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
 477                 throw new RetiredGenerationException(existing.getIdentifier().getGeneration());
 478             }
 479
 480             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 481             existing.retire();
 482             knownFrontends.remove(clientId.getFrontendId());
 483         } else {
 484             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 485         }
 486
 487         return null;
 488     }
 489
 490     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 491         final LeaderFrontendState ret = findFrontend(clientId);
 492         if (ret != null) {
 493             return ret;
 494         }
 495
 496         // TODO: a dedicated exception would be better, but this is technically true, too
 497         throw new OutOfSequenceEnvelopeException(0);
 498     }
 499
 500     @Nonnull
 501     private static ABIVersion selectVersion(final ConnectClientRequest message) {
 502         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
 503         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
 504             if (clientRange.contains(v)) {
 505                 return v;
 506             }
 507         }
 508
 509         throw new IllegalArgumentException(String.format(
 510             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
 511             clientRange));
 512     }
 513
 514     @SuppressWarnings("checkstyle:IllegalCatch")
 515     private void handleConnectClient(final ConnectClientRequest message) {
 516         try {
 517             final ClientIdentifier clientId = message.getTarget();
 518             final LeaderFrontendState existing = findFrontend(clientId);
 519             if (existing != null) {
 520                 existing.touch();
 521             }
 522
 523             if (!isLeader() || !isLeaderActive()) {
 524                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 525                                 + "isLeadershipTransferInProgress: {}.",
 526                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
 527                 throw new NotLeaderException(getSelf());
 528             }
 529
 530             final ABIVersion selectedVersion = selectVersion(message);
 531             final LeaderFrontendState frontend;
 532             if (existing == null) {
 533                 frontend = new LeaderFrontendState(persistenceId(), clientId, store);
 534                 knownFrontends.put(clientId.getFrontendId(), frontend);
 535                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
 536             } else {
 537                 frontend = existing;
 538             }
 539
 540             frontend.reconnect();
 541             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
 542                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
 543                 ActorRef.noSender());
 544         } catch (RequestException | RuntimeException e) {
 545             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
 546         }
 547     }
 548
 549     @Nullable
 550     private RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 551             throws RequestException {
 552         // We are not the leader, hence we want to fail-fast.
 553         if (!isLeader() || paused || !isLeaderActive()) {
 554             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 555                             + "isLeadershipTransferInProgress: {}, paused: {}",
 556                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 557             throw new NotLeaderException(getSelf());
 558         }
 559
 560         final Request<?, ?> request = envelope.getMessage();
 561         if (request instanceof TransactionRequest) {
 562             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
 563             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
 564             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 565         } else if (request instanceof LocalHistoryRequest) {
 566             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
 567             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
 568             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 569         } else {
 570             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 571             throw new UnsupportedRequestException(request);
 572         }
 573     }
 574
 575     private boolean hasLeader() {
 576         return getLeaderId() != null;
 577     }
 578
 579     public int getPendingTxCommitQueueSize() {
 580         return store.getQueueSize();
 581     }
 582
 583     public int getCohortCacheSize() {
 584         return commitCoordinator.getCohortCacheSize();
 585     }
 586
 587     @Override
 588     protected Optional<ActorRef> getRoleChangeNotifier() {
 589         return roleChangeNotifier;
 590     }
 591
 592     String getShardName() {
 593         return shardName;
 594     }
 595
 596     @Override
 597     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 598             final short leaderPayloadVersion) {
 599         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 600                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 601     }
 602
 603     protected void onDatastoreContext(final DatastoreContext context) {
 604         datastoreContext = context;
 605
 606         setTransactionCommitTimeout();
 607
 608         setPersistence(datastoreContext.isPersistent());
 609
 610         updateConfigParams(datastoreContext.getShardRaftConfig());
 611     }
 612
 613     // applyState() will be invoked once consensus is reached on the payload
 614     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 615         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 616         if (canSkipPayload) {
 617             applyState(self(), id, payload);
 618         } else {
 619             // We are faking the sender
 620             persistData(self(), id, payload, batchHint);
 621         }
 622     }
 623
 624     private void handleCommitTransaction(final CommitTransaction commit) {
 625         if (isLeader()) {
 626             commitCoordinator.handleCommit(commit.getTransactionId(), getSender(), this);
 627         } else {
 628             ActorSelection leader = getLeader();
 629             if (leader == null) {
 630                 messageRetrySupport.addMessageToRetry(commit, getSender(),
 631                         "Could not commit transaction " + commit.getTransactionId());
 632             } else {
 633                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 634                 leader.forward(commit, getContext());
 635             }
 636         }
 637     }
 638
 639     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 640         LOG.debug("{}: Can committing transaction {}", persistenceId(), canCommit.getTransactionId());
 641
 642         if (isLeader()) {
 643             commitCoordinator.handleCanCommit(canCommit.getTransactionId(), getSender(), this);
 644         } else {
 645             ActorSelection leader = getLeader();
 646             if (leader == null) {
 647                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 648                         "Could not canCommit transaction " + canCommit.getTransactionId());
 649             } else {
 650                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 651                 leader.forward(canCommit, getContext());
 652             }
 653         }
 654     }
 655
 656     @SuppressWarnings("checkstyle:IllegalCatch")
 657     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 658         try {
 659             commitCoordinator.handleBatchedModifications(batched, sender, this);
 660         } catch (Exception e) {
 661             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 662                     batched.getTransactionId(), e);
 663             sender.tell(new Failure(e), getSelf());
 664         }
 665     }
 666
 667     private void handleBatchedModifications(final BatchedModifications batched) {
 668         // This message is sent to prepare the modifications transaction directly on the Shard as an
 669         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 670         // BatchedModifications message, the caller sets the ready flag in the message indicating
 671         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 672         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 673         // ReadyTransaction message.
 674
 675         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 676         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 677         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 678         // window where it could have a stale leader during leadership transitions.
 679         //
 680         boolean isLeaderActive = isLeaderActive();
 681         if (isLeader() && isLeaderActive) {
 682             handleBatchedModificationsLocal(batched, getSender());
 683         } else {
 684             ActorSelection leader = getLeader();
 685             if (!isLeaderActive || leader == null) {
 686                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 687                         "Could not process BatchedModifications " + batched.getTransactionId());
 688             } else {
 689                 // If this is not the first batch and leadership changed in between batched messages,
 690                 // we need to reconstruct previous BatchedModifications from the transaction
 691                 // DataTreeModification, honoring the max batched modification count, and forward all the
 692                 // previous BatchedModifications to the new leader.
 693                 Collection<BatchedModifications> newModifications = commitCoordinator
 694                         .createForwardedBatchedModifications(batched,
 695                                 datastoreContext.getShardBatchedModificationCount());
 696
 697                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 698                         newModifications.size(), leader);
 699
 700                 for (BatchedModifications bm : newModifications) {
 701                     leader.forward(bm, getContext());
 702                 }
 703             }
 704         }
 705     }
 706
 707     private boolean failIfIsolatedLeader(final ActorRef sender) {
 708         if (isIsolatedLeader()) {
 709             sender.tell(new Failure(new NoShardLeaderException(String.format(
 710                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 711                     + " other follower nodes are down or this node is isolated by a network partition.",
 712                     persistenceId()))), getSelf());
 713             return true;
 714         }
 715
 716         return false;
 717     }
 718
 719     protected boolean isIsolatedLeader() {
 720         return getRaftState() == RaftState.IsolatedLeader;
 721     }
 722
 723     @SuppressWarnings("checkstyle:IllegalCatch")
 724     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 725         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
 726
 727         boolean isLeaderActive = isLeaderActive();
 728         if (isLeader() && isLeaderActive) {
 729             try {
 730                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 731             } catch (Exception e) {
 732                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
 733                         message.getTransactionId(), e);
 734                 getSender().tell(new Failure(e), getSelf());
 735             }
 736         } else {
 737             ActorSelection leader = getLeader();
 738             if (!isLeaderActive || leader == null) {
 739                 messageRetrySupport.addMessageToRetry(message, getSender(),
 740                         "Could not process ready local transaction " + message.getTransactionId());
 741             } else {
 742                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 743                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 744                 leader.forward(message, getContext());
 745             }
 746         }
 747     }
 748
 749     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 750         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 751
 752         boolean isLeaderActive = isLeaderActive();
 753         if (isLeader() && isLeaderActive) {
 754             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 755         } else {
 756             ActorSelection leader = getLeader();
 757             if (!isLeaderActive || leader == null) {
 758                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 759                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 760             } else {
 761                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 762
 763                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 764                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 765                         forwardedReady.getParticipatingShardNames());
 766                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 767                 leader.forward(readyLocal, getContext());
 768             }
 769         }
 770     }
 771
 772     private void handleAbortTransaction(final AbortTransaction abort) {
 773         doAbortTransaction(abort.getTransactionId(), getSender());
 774     }
 775
 776     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 777         commitCoordinator.handleAbort(transactionID, sender, this);
 778     }
 779
 780     private void handleCreateTransaction(final Object message) {
 781         if (isLeader()) {
 782             createTransaction(CreateTransaction.fromSerializable(message));
 783         } else if (getLeader() != null) {
 784             getLeader().forward(message, getContext());
 785         } else {
 786             getSender().tell(new Failure(new NoShardLeaderException(
 787                     "Could not create a shard transaction", persistenceId())), getSelf());
 788         }
 789     }
 790
 791     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 792         final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 793         store.closeTransactionChain(id, null);
 794         store.purgeTransactionChain(id, null);
 795     }
 796
 797     @SuppressWarnings("checkstyle:IllegalCatch")
 798     private void createTransaction(final CreateTransaction createTransaction) {
 799         try {
 800             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
 801                     && failIfIsolatedLeader(getSender())) {
 802                 return;
 803             }
 804
 805             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 806                 createTransaction.getTransactionId());
 807
 808             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 809                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 810         } catch (Exception e) {
 811             getSender().tell(new Failure(e), getSelf());
 812         }
 813     }
 814
 815     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
 816         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 817         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 818             transactionId);
 819     }
 820
 821     private void updateSchemaContext(final UpdateSchemaContext message) {
 822         updateSchemaContext(message.getSchemaContext());
 823     }
 824
 825     @VisibleForTesting
 826     void updateSchemaContext(final SchemaContext schemaContext) {
 827         store.updateSchemaContext(schemaContext);
 828     }
 829
 830     private boolean isMetricsCaptureEnabled() {
 831         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 832         return config.isMetricCaptureEnabled();
 833     }
 834
 835     @Override
 836     @VisibleForTesting
 837     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 838         return snapshotCohort;
 839     }
 840
 841     @Override
 842     @Nonnull
 843     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 844         if (restoreFromSnapshot == null) {
 845             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 846         }
 847
 848         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 849     }
 850
 851     @Override
 852     protected void onRecoveryComplete() {
 853         restoreFromSnapshot = null;
 854
 855         //notify shard manager
 856         getContext().parent().tell(new ActorInitialized(), getSelf());
 857
 858         // Being paranoid here - this method should only be called once but just in case...
 859         if (txCommitTimeoutCheckSchedule == null) {
 860             // Schedule a message to be periodically sent to check if the current in-progress
 861             // transaction should be expired and aborted.
 862             FiniteDuration period = Duration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 863             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 864                     period, period, getSelf(),
 865                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 866         }
 867     }
 868
 869     @Override
 870     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 871         if (data instanceof Payload) {
 872             try {
 873                 store.applyReplicatedPayload(identifier, (Payload)data);
 874             } catch (DataValidationFailedException | IOException e) {
 875                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 876             }
 877         } else {
 878             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
 879         }
 880     }
 881
 882     @Override
 883     protected void onStateChanged() {
 884         boolean isLeader = isLeader();
 885         boolean hasLeader = hasLeader();
 886         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
 887
 888         // If this actor is no longer the leader close all the transaction chains
 889         if (!isLeader) {
 890             if (LOG.isDebugEnabled()) {
 891                 LOG.debug(
 892                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
 893                     persistenceId(), getId());
 894             }
 895
 896             paused = false;
 897             store.purgeLeaderState();
 898         }
 899
 900         if (hasLeader && !isIsolatedLeader()) {
 901             messageRetrySupport.retryMessages();
 902         }
 903     }
 904
 905     @Override
 906     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
 907         shardMBean.incrementLeadershipChangeCount();
 908         paused = false;
 909
 910         if (!isLeader()) {
 911             if (!knownFrontends.isEmpty()) {
 912                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
 913                 knownFrontends = ImmutableMap.of();
 914             }
 915
 916             requestMessageAssembler.close();
 917
 918             if (!hasLeader()) {
 919                 // No leader anywhere, nothing else to do
 920                 return;
 921             }
 922
 923             // Another leader was elected. If we were the previous leader and had pending transactions, convert
 924             // them to transaction messages and send to the new leader.
 925             ActorSelection leader = getLeader();
 926             if (leader != null) {
 927                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
 928
 929                 if (!messagesToForward.isEmpty()) {
 930                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
 931                             messagesToForward.size(), leader);
 932
 933                     for (Object message : messagesToForward) {
 934                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
 935
 936                         leader.tell(message, self());
 937                     }
 938                 }
 939             } else {
 940                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
 941                         + "change and the leader address isn't available.", this);
 942             }
 943         } else {
 944             // We have become the leader, we need to reconstruct frontend state
 945             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 946             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
 947         }
 948
 949         if (!isIsolatedLeader()) {
 950             messageRetrySupport.retryMessages();
 951         }
 952     }
 953
 954     /**
 955      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
 956      *
 957      * @return the converted messages
 958      */
 959     public Collection<?> convertPendingTransactionsToMessages() {
 960         return commitCoordinator.convertPendingTransactionsToMessages(
 961                 datastoreContext.getShardBatchedModificationCount());
 962     }
 963
 964     @Override
 965     protected void pauseLeader(final Runnable operation) {
 966         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
 967         paused = true;
 968
 969         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
 970         knownFrontends.values().forEach(LeaderFrontendState::retire);
 971         knownFrontends = ImmutableMap.of();
 972
 973         store.setRunOnPendingTransactionsComplete(operation);
 974     }
 975
 976     @Override
 977     protected void unpauseLeader() {
 978         LOG.debug("{}: In unpauseLeader", persistenceId());
 979         paused = false;
 980
 981         store.setRunOnPendingTransactionsComplete(null);
 982
 983         // Restore tell-based protocol state as if we were becoming the leader
 984         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 985     }
 986
 987     @Override
 988     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
 989         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
 990                 .commitCohortActors(store.getCohortActors());
 991     }
 992
 993     @Override
 994     public String persistenceId() {
 995         return this.name;
 996     }
 997
 998     @VisibleForTesting
 999     ShardCommitCoordinator getCommitCoordinator() {
1000         return commitCoordinator;
1001     }
1002
1003     public DatastoreContext getDatastoreContext() {
1004         return datastoreContext;
1005     }
1006
1007     @VisibleForTesting
1008     public ShardDataTree getDataStore() {
1009         return store;
1010     }
1011
1012     @VisibleForTesting
1013     ShardStats getShardMBean() {
1014         return shardMBean;
1015     }
1016
1017     public static Builder builder() {
1018         return new Builder();
1019     }
1020
1021     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1022         private final Class<S> shardClass;
1023         private ShardIdentifier id;
1024         private Map<String, String> peerAddresses = Collections.emptyMap();
1025         private DatastoreContext datastoreContext;
1026         private SchemaContextProvider schemaContextProvider;
1027         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1028         private DataTree dataTree;
1029         private volatile boolean sealed;
1030
1031         protected AbstractBuilder(final Class<S> shardClass) {
1032             this.shardClass = shardClass;
1033         }
1034
1035         protected void checkSealed() {
1036             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1037         }
1038
1039         @SuppressWarnings("unchecked")
1040         private T self() {
1041             return (T) this;
1042         }
1043
1044         public T id(final ShardIdentifier newId) {
1045             checkSealed();
1046             this.id = newId;
1047             return self();
1048         }
1049
1050         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1051             checkSealed();
1052             this.peerAddresses = newPeerAddresses;
1053             return self();
1054         }
1055
1056         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1057             checkSealed();
1058             this.datastoreContext = newDatastoreContext;
1059             return self();
1060         }
1061
1062         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1063             checkSealed();
1064             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1065             return self();
1066         }
1067
1068         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1069             checkSealed();
1070             this.restoreFromSnapshot = newRestoreFromSnapshot;
1071             return self();
1072         }
1073
1074         public T dataTree(final DataTree newDataTree) {
1075             checkSealed();
1076             this.dataTree = newDataTree;
1077             return self();
1078         }
1079
1080         public ShardIdentifier getId() {
1081             return id;
1082         }
1083
1084         public Map<String, String> getPeerAddresses() {
1085             return peerAddresses;
1086         }
1087
1088         public DatastoreContext getDatastoreContext() {
1089             return datastoreContext;
1090         }
1091
1092         public SchemaContext getSchemaContext() {
1093             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1094         }
1095
1096         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1097             return restoreFromSnapshot;
1098         }
1099
1100         public DataTree getDataTree() {
1101             return dataTree;
1102         }
1103
1104         public TreeType getTreeType() {
1105             switch (datastoreContext.getLogicalStoreType()) {
1106                 case CONFIGURATION:
1107                     return TreeType.CONFIGURATION;
1108                 case OPERATIONAL:
1109                     return TreeType.OPERATIONAL;
1110                 default:
1111                     throw new IllegalStateException("Unhandled logical store type "
1112                             + datastoreContext.getLogicalStoreType());
1113             }
1114         }
1115
1116         protected void verify() {
1117             Preconditions.checkNotNull(id, "id should not be null");
1118             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1119             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1120             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1121         }
1122
1123         public Props props() {
1124             sealed = true;
1125             verify();
1126             return Props.create(shardClass, this);
1127         }
1128     }
1129
1130     public static class Builder extends AbstractBuilder<Builder, Shard> {
1131         Builder() {
1132             super(Shard.class);
1133         }
1134     }
1135
1136     Ticker ticker() {
1137         return Ticker.systemTicker();
1138     }
1139
1140     void scheduleNextPendingTransaction() {
1141         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1142     }
1143 }