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(clientId.getGeneration(),
 478                     existing.getIdentifier().getGeneration());
 479             }
 480
 481             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 482             existing.retire();
 483             knownFrontends.remove(clientId.getFrontendId());
 484         } else {
 485             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 486         }
 487
 488         return null;
 489     }
 490
 491     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 492         final LeaderFrontendState ret = findFrontend(clientId);
 493         if (ret != null) {
 494             return ret;
 495         }
 496
 497         // TODO: a dedicated exception would be better, but this is technically true, too
 498         throw new OutOfSequenceEnvelopeException(0);
 499     }
 500
 501     @Nonnull
 502     private static ABIVersion selectVersion(final ConnectClientRequest message) {
 503         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
 504         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
 505             if (clientRange.contains(v)) {
 506                 return v;
 507             }
 508         }
 509
 510         throw new IllegalArgumentException(String.format(
 511             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
 512             clientRange));
 513     }
 514
 515     @SuppressWarnings("checkstyle:IllegalCatch")
 516     private void handleConnectClient(final ConnectClientRequest message) {
 517         try {
 518             final ClientIdentifier clientId = message.getTarget();
 519             final LeaderFrontendState existing = findFrontend(clientId);
 520             if (existing != null) {
 521                 existing.touch();
 522             }
 523
 524             if (!isLeader() || !isLeaderActive()) {
 525                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 526                                 + "isLeadershipTransferInProgress: {}.",
 527                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
 528                 throw new NotLeaderException(getSelf());
 529             }
 530
 531             final ABIVersion selectedVersion = selectVersion(message);
 532             final LeaderFrontendState frontend;
 533             if (existing == null) {
 534                 frontend = new LeaderFrontendState(persistenceId(), clientId, store);
 535                 knownFrontends.put(clientId.getFrontendId(), frontend);
 536                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
 537             } else {
 538                 frontend = existing;
 539             }
 540
 541             frontend.reconnect();
 542             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
 543                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
 544                 ActorRef.noSender());
 545         } catch (RequestException | RuntimeException e) {
 546             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
 547         }
 548     }
 549
 550     @Nullable
 551     private RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 552             throws RequestException {
 553         // We are not the leader, hence we want to fail-fast.
 554         if (!isLeader() || paused || !isLeaderActive()) {
 555             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 556                             + "isLeadershipTransferInProgress: {}, paused: {}",
 557                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 558             throw new NotLeaderException(getSelf());
 559         }
 560
 561         final Request<?, ?> request = envelope.getMessage();
 562         if (request instanceof TransactionRequest) {
 563             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
 564             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
 565             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 566         } else if (request instanceof LocalHistoryRequest) {
 567             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
 568             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
 569             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 570         } else {
 571             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 572             throw new UnsupportedRequestException(request);
 573         }
 574     }
 575
 576     private boolean hasLeader() {
 577         return getLeaderId() != null;
 578     }
 579
 580     public int getPendingTxCommitQueueSize() {
 581         return store.getQueueSize();
 582     }
 583
 584     public int getCohortCacheSize() {
 585         return commitCoordinator.getCohortCacheSize();
 586     }
 587
 588     @Override
 589     protected Optional<ActorRef> getRoleChangeNotifier() {
 590         return roleChangeNotifier;
 591     }
 592
 593     String getShardName() {
 594         return shardName;
 595     }
 596
 597     @Override
 598     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 599             final short leaderPayloadVersion) {
 600         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 601                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 602     }
 603
 604     protected void onDatastoreContext(final DatastoreContext context) {
 605         datastoreContext = context;
 606
 607         setTransactionCommitTimeout();
 608
 609         setPersistence(datastoreContext.isPersistent());
 610
 611         updateConfigParams(datastoreContext.getShardRaftConfig());
 612     }
 613
 614     // applyState() will be invoked once consensus is reached on the payload
 615     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 616         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 617         if (canSkipPayload) {
 618             applyState(self(), id, payload);
 619         } else {
 620             // We are faking the sender
 621             persistData(self(), id, payload, batchHint);
 622         }
 623     }
 624
 625     private void handleCommitTransaction(final CommitTransaction commit) {
 626         if (isLeader()) {
 627             commitCoordinator.handleCommit(commit.getTransactionId(), getSender(), this);
 628         } else {
 629             ActorSelection leader = getLeader();
 630             if (leader == null) {
 631                 messageRetrySupport.addMessageToRetry(commit, getSender(),
 632                         "Could not commit transaction " + commit.getTransactionId());
 633             } else {
 634                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 635                 leader.forward(commit, getContext());
 636             }
 637         }
 638     }
 639
 640     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 641         LOG.debug("{}: Can committing transaction {}", persistenceId(), canCommit.getTransactionId());
 642
 643         if (isLeader()) {
 644             commitCoordinator.handleCanCommit(canCommit.getTransactionId(), getSender(), this);
 645         } else {
 646             ActorSelection leader = getLeader();
 647             if (leader == null) {
 648                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 649                         "Could not canCommit transaction " + canCommit.getTransactionId());
 650             } else {
 651                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 652                 leader.forward(canCommit, getContext());
 653             }
 654         }
 655     }
 656
 657     @SuppressWarnings("checkstyle:IllegalCatch")
 658     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 659         try {
 660             commitCoordinator.handleBatchedModifications(batched, sender, this);
 661         } catch (Exception e) {
 662             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 663                     batched.getTransactionId(), e);
 664             sender.tell(new Failure(e), getSelf());
 665         }
 666     }
 667
 668     private void handleBatchedModifications(final BatchedModifications batched) {
 669         // This message is sent to prepare the modifications transaction directly on the Shard as an
 670         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 671         // BatchedModifications message, the caller sets the ready flag in the message indicating
 672         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 673         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 674         // ReadyTransaction message.
 675
 676         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 677         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 678         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 679         // window where it could have a stale leader during leadership transitions.
 680         //
 681         boolean isLeaderActive = isLeaderActive();
 682         if (isLeader() && isLeaderActive) {
 683             handleBatchedModificationsLocal(batched, getSender());
 684         } else {
 685             ActorSelection leader = getLeader();
 686             if (!isLeaderActive || leader == null) {
 687                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 688                         "Could not process BatchedModifications " + batched.getTransactionId());
 689             } else {
 690                 // If this is not the first batch and leadership changed in between batched messages,
 691                 // we need to reconstruct previous BatchedModifications from the transaction
 692                 // DataTreeModification, honoring the max batched modification count, and forward all the
 693                 // previous BatchedModifications to the new leader.
 694                 Collection<BatchedModifications> newModifications = commitCoordinator
 695                         .createForwardedBatchedModifications(batched,
 696                                 datastoreContext.getShardBatchedModificationCount());
 697
 698                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 699                         newModifications.size(), leader);
 700
 701                 for (BatchedModifications bm : newModifications) {
 702                     leader.forward(bm, getContext());
 703                 }
 704             }
 705         }
 706     }
 707
 708     private boolean failIfIsolatedLeader(final ActorRef sender) {
 709         if (isIsolatedLeader()) {
 710             sender.tell(new Failure(new NoShardLeaderException(String.format(
 711                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 712                     + " other follower nodes are down or this node is isolated by a network partition.",
 713                     persistenceId()))), getSelf());
 714             return true;
 715         }
 716
 717         return false;
 718     }
 719
 720     protected boolean isIsolatedLeader() {
 721         return getRaftState() == RaftState.IsolatedLeader;
 722     }
 723
 724     @SuppressWarnings("checkstyle:IllegalCatch")
 725     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 726         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
 727
 728         boolean isLeaderActive = isLeaderActive();
 729         if (isLeader() && isLeaderActive) {
 730             try {
 731                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 732             } catch (Exception e) {
 733                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
 734                         message.getTransactionId(), e);
 735                 getSender().tell(new Failure(e), getSelf());
 736             }
 737         } else {
 738             ActorSelection leader = getLeader();
 739             if (!isLeaderActive || leader == null) {
 740                 messageRetrySupport.addMessageToRetry(message, getSender(),
 741                         "Could not process ready local transaction " + message.getTransactionId());
 742             } else {
 743                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 744                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 745                 leader.forward(message, getContext());
 746             }
 747         }
 748     }
 749
 750     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 751         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 752
 753         boolean isLeaderActive = isLeaderActive();
 754         if (isLeader() && isLeaderActive) {
 755             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 756         } else {
 757             ActorSelection leader = getLeader();
 758             if (!isLeaderActive || leader == null) {
 759                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 760                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 761             } else {
 762                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 763
 764                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 765                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 766                         forwardedReady.getParticipatingShardNames());
 767                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 768                 leader.forward(readyLocal, getContext());
 769             }
 770         }
 771     }
 772
 773     private void handleAbortTransaction(final AbortTransaction abort) {
 774         doAbortTransaction(abort.getTransactionId(), getSender());
 775     }
 776
 777     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 778         commitCoordinator.handleAbort(transactionID, sender, this);
 779     }
 780
 781     private void handleCreateTransaction(final Object message) {
 782         if (isLeader()) {
 783             createTransaction(CreateTransaction.fromSerializable(message));
 784         } else if (getLeader() != null) {
 785             getLeader().forward(message, getContext());
 786         } else {
 787             getSender().tell(new Failure(new NoShardLeaderException(
 788                     "Could not create a shard transaction", persistenceId())), getSelf());
 789         }
 790     }
 791
 792     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 793         final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 794         store.closeTransactionChain(id, null);
 795         store.purgeTransactionChain(id, null);
 796     }
 797
 798     @SuppressWarnings("checkstyle:IllegalCatch")
 799     private void createTransaction(final CreateTransaction createTransaction) {
 800         try {
 801             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
 802                     && failIfIsolatedLeader(getSender())) {
 803                 return;
 804             }
 805
 806             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 807                 createTransaction.getTransactionId());
 808
 809             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 810                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 811         } catch (Exception e) {
 812             getSender().tell(new Failure(e), getSelf());
 813         }
 814     }
 815
 816     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
 817         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 818         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 819             transactionId);
 820     }
 821
 822     private void updateSchemaContext(final UpdateSchemaContext message) {
 823         updateSchemaContext(message.getSchemaContext());
 824     }
 825
 826     @VisibleForTesting
 827     void updateSchemaContext(final SchemaContext schemaContext) {
 828         store.updateSchemaContext(schemaContext);
 829     }
 830
 831     private boolean isMetricsCaptureEnabled() {
 832         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 833         return config.isMetricCaptureEnabled();
 834     }
 835
 836     @Override
 837     @VisibleForTesting
 838     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 839         return snapshotCohort;
 840     }
 841
 842     @Override
 843     @Nonnull
 844     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 845         if (restoreFromSnapshot == null) {
 846             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 847         }
 848
 849         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 850     }
 851
 852     @Override
 853     protected void onRecoveryComplete() {
 854         restoreFromSnapshot = null;
 855
 856         //notify shard manager
 857         getContext().parent().tell(new ActorInitialized(), getSelf());
 858
 859         // Being paranoid here - this method should only be called once but just in case...
 860         if (txCommitTimeoutCheckSchedule == null) {
 861             // Schedule a message to be periodically sent to check if the current in-progress
 862             // transaction should be expired and aborted.
 863             FiniteDuration period = Duration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 864             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 865                     period, period, getSelf(),
 866                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 867         }
 868     }
 869
 870     @Override
 871     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 872         if (data instanceof Payload) {
 873             try {
 874                 store.applyReplicatedPayload(identifier, (Payload)data);
 875             } catch (DataValidationFailedException | IOException e) {
 876                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 877             }
 878         } else {
 879             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
 880         }
 881     }
 882
 883     @Override
 884     protected void onStateChanged() {
 885         boolean isLeader = isLeader();
 886         boolean hasLeader = hasLeader();
 887         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
 888
 889         // If this actor is no longer the leader close all the transaction chains
 890         if (!isLeader) {
 891             if (LOG.isDebugEnabled()) {
 892                 LOG.debug(
 893                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
 894                     persistenceId(), getId());
 895             }
 896
 897             paused = false;
 898             store.purgeLeaderState();
 899         }
 900
 901         if (hasLeader && !isIsolatedLeader()) {
 902             messageRetrySupport.retryMessages();
 903         }
 904     }
 905
 906     @Override
 907     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
 908         shardMBean.incrementLeadershipChangeCount();
 909         paused = false;
 910
 911         if (!isLeader()) {
 912             if (!knownFrontends.isEmpty()) {
 913                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
 914                 knownFrontends = ImmutableMap.of();
 915             }
 916
 917             requestMessageAssembler.close();
 918
 919             if (!hasLeader()) {
 920                 // No leader anywhere, nothing else to do
 921                 return;
 922             }
 923
 924             // Another leader was elected. If we were the previous leader and had pending transactions, convert
 925             // them to transaction messages and send to the new leader.
 926             ActorSelection leader = getLeader();
 927             if (leader != null) {
 928                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
 929
 930                 if (!messagesToForward.isEmpty()) {
 931                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
 932                             messagesToForward.size(), leader);
 933
 934                     for (Object message : messagesToForward) {
 935                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
 936
 937                         leader.tell(message, self());
 938                     }
 939                 }
 940             } else {
 941                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
 942                         + "change and the leader address isn't available.", this);
 943             }
 944         } else {
 945             // We have become the leader, we need to reconstruct frontend state
 946             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 947             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
 948         }
 949
 950         if (!isIsolatedLeader()) {
 951             messageRetrySupport.retryMessages();
 952         }
 953     }
 954
 955     /**
 956      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
 957      *
 958      * @return the converted messages
 959      */
 960     public Collection<?> convertPendingTransactionsToMessages() {
 961         return commitCoordinator.convertPendingTransactionsToMessages(
 962                 datastoreContext.getShardBatchedModificationCount());
 963     }
 964
 965     @Override
 966     protected void pauseLeader(final Runnable operation) {
 967         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
 968         paused = true;
 969
 970         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
 971         knownFrontends.values().forEach(LeaderFrontendState::retire);
 972         knownFrontends = ImmutableMap.of();
 973
 974         store.setRunOnPendingTransactionsComplete(operation);
 975     }
 976
 977     @Override
 978     protected void unpauseLeader() {
 979         LOG.debug("{}: In unpauseLeader", persistenceId());
 980         paused = false;
 981
 982         store.setRunOnPendingTransactionsComplete(null);
 983
 984         // Restore tell-based protocol state as if we were becoming the leader
 985         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 986     }
 987
 988     @Override
 989     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
 990         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
 991                 .commitCohortActors(store.getCohortActors());
 992     }
 993
 994     @Override
 995     public String persistenceId() {
 996         return this.name;
 997     }
 998
 999     @VisibleForTesting
1000     ShardCommitCoordinator getCommitCoordinator() {
1001         return commitCoordinator;
1002     }
1003
1004     public DatastoreContext getDatastoreContext() {
1005         return datastoreContext;
1006     }
1007
1008     @VisibleForTesting
1009     public ShardDataTree getDataStore() {
1010         return store;
1011     }
1012
1013     @VisibleForTesting
1014     ShardStats getShardMBean() {
1015         return shardMBean;
1016     }
1017
1018     public static Builder builder() {
1019         return new Builder();
1020     }
1021
1022     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1023         private final Class<S> shardClass;
1024         private ShardIdentifier id;
1025         private Map<String, String> peerAddresses = Collections.emptyMap();
1026         private DatastoreContext datastoreContext;
1027         private SchemaContextProvider schemaContextProvider;
1028         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1029         private DataTree dataTree;
1030         private volatile boolean sealed;
1031
1032         protected AbstractBuilder(final Class<S> shardClass) {
1033             this.shardClass = shardClass;
1034         }
1035
1036         protected void checkSealed() {
1037             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1038         }
1039
1040         @SuppressWarnings("unchecked")
1041         private T self() {
1042             return (T) this;
1043         }
1044
1045         public T id(final ShardIdentifier newId) {
1046             checkSealed();
1047             this.id = newId;
1048             return self();
1049         }
1050
1051         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1052             checkSealed();
1053             this.peerAddresses = newPeerAddresses;
1054             return self();
1055         }
1056
1057         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1058             checkSealed();
1059             this.datastoreContext = newDatastoreContext;
1060             return self();
1061         }
1062
1063         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1064             checkSealed();
1065             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1066             return self();
1067         }
1068
1069         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1070             checkSealed();
1071             this.restoreFromSnapshot = newRestoreFromSnapshot;
1072             return self();
1073         }
1074
1075         public T dataTree(final DataTree newDataTree) {
1076             checkSealed();
1077             this.dataTree = newDataTree;
1078             return self();
1079         }
1080
1081         public ShardIdentifier getId() {
1082             return id;
1083         }
1084
1085         public Map<String, String> getPeerAddresses() {
1086             return peerAddresses;
1087         }
1088
1089         public DatastoreContext getDatastoreContext() {
1090             return datastoreContext;
1091         }
1092
1093         public SchemaContext getSchemaContext() {
1094             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1095         }
1096
1097         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1098             return restoreFromSnapshot;
1099         }
1100
1101         public DataTree getDataTree() {
1102             return dataTree;
1103         }
1104
1105         public TreeType getTreeType() {
1106             switch (datastoreContext.getLogicalStoreType()) {
1107                 case CONFIGURATION:
1108                     return TreeType.CONFIGURATION;
1109                 case OPERATIONAL:
1110                     return TreeType.OPERATIONAL;
1111                 default:
1112                     throw new IllegalStateException("Unhandled logical store type "
1113                             + datastoreContext.getLogicalStoreType());
1114             }
1115         }
1116
1117         protected void verify() {
1118             Preconditions.checkNotNull(id, "id should not be null");
1119             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1120             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1121             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1122         }
1123
1124         public Props props() {
1125             sealed = true;
1126             verify();
1127             return Props.create(shardClass, this);
1128         }
1129     }
1130
1131     public static class Builder extends AbstractBuilder<Builder, Shard> {
1132         Builder() {
1133             super(Shard.class);
1134         }
1135     }
1136
1137     Ticker ticker() {
1138         return Ticker.systemTicker();
1139     }
1140
1141     void scheduleNextPendingTransaction() {
1142         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1143     }
1144 }