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 -> LOG.warn("Error slicing response {}", success, t)).build()));
 399                 } else {
 400                     envelope.sendSuccess(success, executionTimeNanos);
 401                 }
 402             }
 403         } catch (RequestException e) {
 404             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
 405             envelope.sendFailure(e, ticker().read() - now);
 406         } catch (Exception e) {
 407             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
 408             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
 409                 ticker().read() - now);
 410         }
 411     }
 412
 413     private void commitTimeoutCheck() {
 414         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
 415         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
 416         requestMessageAssembler.checkExpiredAssembledMessageState();
 417     }
 418
 419     private Optional<Long> updateAccess(final SimpleShardDataTreeCohort cohort) {
 420         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
 421         final LeaderFrontendState state = knownFrontends.get(frontend);
 422         if (state == null) {
 423             // Not tell-based protocol, do nothing
 424             return Optional.absent();
 425         }
 426
 427         if (isIsolatedLeader()) {
 428             // We are isolated and no new request can come through until we emerge from it. We are still updating
 429             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
 430             return Optional.of(state.getLastSeenTicks());
 431         }
 432
 433         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
 434         return Optional.of(state.getLastConnectTicks());
 435     }
 436
 437     private void onMakeLeaderLocal() {
 438         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
 439         if (isLeader()) {
 440             getSender().tell(new Status.Success(null), getSelf());
 441             return;
 442         }
 443
 444         final ActorSelection leader = getLeader();
 445
 446         if (leader == null) {
 447             // Leader is not present. The cluster is most likely trying to
 448             // elect a leader and we should let that run its normal course
 449
 450             // TODO we can wait for the election to complete and retry the
 451             // request. We can also let the caller retry by sending a flag
 452             // in the response indicating the request is "reTryable".
 453             getSender().tell(new Failure(
 454                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
 455                             + "Currently there is no leader for " + persistenceId())),
 456                     getSelf());
 457             return;
 458         }
 459
 460         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
 461     }
 462
 463     // Acquire our frontend tracking handle and verify generation matches
 464     @Nullable
 465     private LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
 466         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
 467         if (existing != null) {
 468             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
 469             if (cmp == 0) {
 470                 existing.touch();
 471                 return existing;
 472             }
 473             if (cmp > 0) {
 474                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
 475                 throw new RetiredGenerationException(clientId.getGeneration(),
 476                     existing.getIdentifier().getGeneration());
 477             }
 478
 479             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 480             existing.retire();
 481             knownFrontends.remove(clientId.getFrontendId());
 482         } else {
 483             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 484         }
 485
 486         return null;
 487     }
 488
 489     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 490         final LeaderFrontendState ret = findFrontend(clientId);
 491         if (ret != null) {
 492             return ret;
 493         }
 494
 495         // TODO: a dedicated exception would be better, but this is technically true, too
 496         throw new OutOfSequenceEnvelopeException(0);
 497     }
 498
 499     @Nonnull
 500     private static ABIVersion selectVersion(final ConnectClientRequest message) {
 501         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
 502         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
 503             if (clientRange.contains(v)) {
 504                 return v;
 505             }
 506         }
 507
 508         throw new IllegalArgumentException(String.format(
 509             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
 510             clientRange));
 511     }
 512
 513     @SuppressWarnings("checkstyle:IllegalCatch")
 514     private void handleConnectClient(final ConnectClientRequest message) {
 515         try {
 516             final ClientIdentifier clientId = message.getTarget();
 517             final LeaderFrontendState existing = findFrontend(clientId);
 518             if (existing != null) {
 519                 existing.touch();
 520             }
 521
 522             if (!isLeader() || !isLeaderActive()) {
 523                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 524                                 + "isLeadershipTransferInProgress: {}.",
 525                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
 526                 throw new NotLeaderException(getSelf());
 527             }
 528
 529             final ABIVersion selectedVersion = selectVersion(message);
 530             final LeaderFrontendState frontend;
 531             if (existing == null) {
 532                 frontend = new LeaderFrontendState(persistenceId(), clientId, store);
 533                 knownFrontends.put(clientId.getFrontendId(), frontend);
 534                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
 535             } else {
 536                 frontend = existing;
 537             }
 538
 539             frontend.reconnect();
 540             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
 541                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
 542                 ActorRef.noSender());
 543         } catch (RequestException | RuntimeException e) {
 544             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
 545         }
 546     }
 547
 548     @Nullable
 549     private RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 550             throws RequestException {
 551         // We are not the leader, hence we want to fail-fast.
 552         if (!isLeader() || paused || !isLeaderActive()) {
 553             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 554                             + "isLeadershipTransferInProgress: {}, paused: {}",
 555                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 556             throw new NotLeaderException(getSelf());
 557         }
 558
 559         final Request<?, ?> request = envelope.getMessage();
 560         if (request instanceof TransactionRequest) {
 561             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
 562             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
 563             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 564         } else if (request instanceof LocalHistoryRequest) {
 565             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
 566             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
 567             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 568         } else {
 569             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 570             throw new UnsupportedRequestException(request);
 571         }
 572     }
 573
 574     private boolean hasLeader() {
 575         return getLeaderId() != null;
 576     }
 577
 578     public int getPendingTxCommitQueueSize() {
 579         return store.getQueueSize();
 580     }
 581
 582     public int getCohortCacheSize() {
 583         return commitCoordinator.getCohortCacheSize();
 584     }
 585
 586     @Override
 587     protected Optional<ActorRef> getRoleChangeNotifier() {
 588         return roleChangeNotifier;
 589     }
 590
 591     String getShardName() {
 592         return shardName;
 593     }
 594
 595     @Override
 596     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 597             final short leaderPayloadVersion) {
 598         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 599                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 600     }
 601
 602     protected void onDatastoreContext(final DatastoreContext context) {
 603         datastoreContext = context;
 604
 605         setTransactionCommitTimeout();
 606
 607         setPersistence(datastoreContext.isPersistent());
 608
 609         updateConfigParams(datastoreContext.getShardRaftConfig());
 610     }
 611
 612     // applyState() will be invoked once consensus is reached on the payload
 613     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 614         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 615         if (canSkipPayload) {
 616             applyState(self(), id, payload);
 617         } else {
 618             // We are faking the sender
 619             persistData(self(), id, payload, batchHint);
 620         }
 621     }
 622
 623     private void handleCommitTransaction(final CommitTransaction commit) {
 624         if (isLeader()) {
 625             commitCoordinator.handleCommit(commit.getTransactionId(), getSender(), this);
 626         } else {
 627             ActorSelection leader = getLeader();
 628             if (leader == null) {
 629                 messageRetrySupport.addMessageToRetry(commit, getSender(),
 630                         "Could not commit transaction " + commit.getTransactionId());
 631             } else {
 632                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 633                 leader.forward(commit, getContext());
 634             }
 635         }
 636     }
 637
 638     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 639         LOG.debug("{}: Can committing transaction {}", persistenceId(), canCommit.getTransactionId());
 640
 641         if (isLeader()) {
 642             commitCoordinator.handleCanCommit(canCommit.getTransactionId(), getSender(), this);
 643         } else {
 644             ActorSelection leader = getLeader();
 645             if (leader == null) {
 646                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 647                         "Could not canCommit transaction " + canCommit.getTransactionId());
 648             } else {
 649                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 650                 leader.forward(canCommit, getContext());
 651             }
 652         }
 653     }
 654
 655     @SuppressWarnings("checkstyle:IllegalCatch")
 656     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 657         try {
 658             commitCoordinator.handleBatchedModifications(batched, sender, this);
 659         } catch (Exception e) {
 660             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 661                     batched.getTransactionId(), e);
 662             sender.tell(new Failure(e), getSelf());
 663         }
 664     }
 665
 666     private void handleBatchedModifications(final BatchedModifications batched) {
 667         // This message is sent to prepare the modifications transaction directly on the Shard as an
 668         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 669         // BatchedModifications message, the caller sets the ready flag in the message indicating
 670         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 671         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 672         // ReadyTransaction message.
 673
 674         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 675         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 676         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 677         // window where it could have a stale leader during leadership transitions.
 678         //
 679         boolean isLeaderActive = isLeaderActive();
 680         if (isLeader() && isLeaderActive) {
 681             handleBatchedModificationsLocal(batched, getSender());
 682         } else {
 683             ActorSelection leader = getLeader();
 684             if (!isLeaderActive || leader == null) {
 685                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 686                         "Could not process BatchedModifications " + batched.getTransactionId());
 687             } else {
 688                 // If this is not the first batch and leadership changed in between batched messages,
 689                 // we need to reconstruct previous BatchedModifications from the transaction
 690                 // DataTreeModification, honoring the max batched modification count, and forward all the
 691                 // previous BatchedModifications to the new leader.
 692                 Collection<BatchedModifications> newModifications = commitCoordinator
 693                         .createForwardedBatchedModifications(batched,
 694                                 datastoreContext.getShardBatchedModificationCount());
 695
 696                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 697                         newModifications.size(), leader);
 698
 699                 for (BatchedModifications bm : newModifications) {
 700                     leader.forward(bm, getContext());
 701                 }
 702             }
 703         }
 704     }
 705
 706     private boolean failIfIsolatedLeader(final ActorRef sender) {
 707         if (isIsolatedLeader()) {
 708             sender.tell(new Failure(new NoShardLeaderException(String.format(
 709                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 710                     + " other follower nodes are down or this node is isolated by a network partition.",
 711                     persistenceId()))), getSelf());
 712             return true;
 713         }
 714
 715         return false;
 716     }
 717
 718     protected boolean isIsolatedLeader() {
 719         return getRaftState() == RaftState.IsolatedLeader;
 720     }
 721
 722     @SuppressWarnings("checkstyle:IllegalCatch")
 723     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 724         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
 725
 726         boolean isLeaderActive = isLeaderActive();
 727         if (isLeader() && isLeaderActive) {
 728             try {
 729                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 730             } catch (Exception e) {
 731                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
 732                         message.getTransactionId(), e);
 733                 getSender().tell(new Failure(e), getSelf());
 734             }
 735         } else {
 736             ActorSelection leader = getLeader();
 737             if (!isLeaderActive || leader == null) {
 738                 messageRetrySupport.addMessageToRetry(message, getSender(),
 739                         "Could not process ready local transaction " + message.getTransactionId());
 740             } else {
 741                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 742                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 743                 leader.forward(message, getContext());
 744             }
 745         }
 746     }
 747
 748     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 749         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 750
 751         boolean isLeaderActive = isLeaderActive();
 752         if (isLeader() && isLeaderActive) {
 753             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 754         } else {
 755             ActorSelection leader = getLeader();
 756             if (!isLeaderActive || leader == null) {
 757                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 758                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 759             } else {
 760                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 761
 762                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 763                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 764                         forwardedReady.getParticipatingShardNames());
 765                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 766                 leader.forward(readyLocal, getContext());
 767             }
 768         }
 769     }
 770
 771     private void handleAbortTransaction(final AbortTransaction abort) {
 772         doAbortTransaction(abort.getTransactionId(), getSender());
 773     }
 774
 775     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 776         commitCoordinator.handleAbort(transactionID, sender, this);
 777     }
 778
 779     private void handleCreateTransaction(final Object message) {
 780         if (isLeader()) {
 781             createTransaction(CreateTransaction.fromSerializable(message));
 782         } else if (getLeader() != null) {
 783             getLeader().forward(message, getContext());
 784         } else {
 785             getSender().tell(new Failure(new NoShardLeaderException(
 786                     "Could not create a shard transaction", persistenceId())), getSelf());
 787         }
 788     }
 789
 790     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 791         final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 792         store.closeTransactionChain(id, null);
 793         store.purgeTransactionChain(id, null);
 794     }
 795
 796     @SuppressWarnings("checkstyle:IllegalCatch")
 797     private void createTransaction(final CreateTransaction createTransaction) {
 798         try {
 799             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
 800                     && failIfIsolatedLeader(getSender())) {
 801                 return;
 802             }
 803
 804             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 805                 createTransaction.getTransactionId());
 806
 807             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 808                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 809         } catch (Exception e) {
 810             getSender().tell(new Failure(e), getSelf());
 811         }
 812     }
 813
 814     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
 815         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 816         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 817             transactionId);
 818     }
 819
 820     private void updateSchemaContext(final UpdateSchemaContext message) {
 821         updateSchemaContext(message.getSchemaContext());
 822     }
 823
 824     @VisibleForTesting
 825     void updateSchemaContext(final SchemaContext schemaContext) {
 826         store.updateSchemaContext(schemaContext);
 827     }
 828
 829     private boolean isMetricsCaptureEnabled() {
 830         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 831         return config.isMetricCaptureEnabled();
 832     }
 833
 834     @Override
 835     @VisibleForTesting
 836     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 837         return snapshotCohort;
 838     }
 839
 840     @Override
 841     @Nonnull
 842     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 843         if (restoreFromSnapshot == null) {
 844             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 845         }
 846
 847         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 848     }
 849
 850     @Override
 851     protected void onRecoveryComplete() {
 852         restoreFromSnapshot = null;
 853
 854         //notify shard manager
 855         getContext().parent().tell(new ActorInitialized(), getSelf());
 856
 857         // Being paranoid here - this method should only be called once but just in case...
 858         if (txCommitTimeoutCheckSchedule == null) {
 859             // Schedule a message to be periodically sent to check if the current in-progress
 860             // transaction should be expired and aborted.
 861             FiniteDuration period = Duration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 862             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 863                     period, period, getSelf(),
 864                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 865         }
 866     }
 867
 868     @Override
 869     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 870         if (data instanceof Payload) {
 871             try {
 872                 store.applyReplicatedPayload(identifier, (Payload)data);
 873             } catch (DataValidationFailedException | IOException e) {
 874                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 875             }
 876         } else {
 877             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
 878         }
 879     }
 880
 881     @Override
 882     protected void onStateChanged() {
 883         boolean isLeader = isLeader();
 884         boolean hasLeader = hasLeader();
 885         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
 886
 887         // If this actor is no longer the leader close all the transaction chains
 888         if (!isLeader) {
 889             if (LOG.isDebugEnabled()) {
 890                 LOG.debug(
 891                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
 892                     persistenceId(), getId());
 893             }
 894
 895             paused = false;
 896             store.purgeLeaderState();
 897         }
 898
 899         if (hasLeader && !isIsolatedLeader()) {
 900             messageRetrySupport.retryMessages();
 901         }
 902     }
 903
 904     @Override
 905     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
 906         shardMBean.incrementLeadershipChangeCount();
 907         paused = false;
 908
 909         if (!isLeader()) {
 910             if (!knownFrontends.isEmpty()) {
 911                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
 912                 knownFrontends = ImmutableMap.of();
 913             }
 914
 915             requestMessageAssembler.close();
 916
 917             if (!hasLeader()) {
 918                 // No leader anywhere, nothing else to do
 919                 return;
 920             }
 921
 922             // Another leader was elected. If we were the previous leader and had pending transactions, convert
 923             // them to transaction messages and send to the new leader.
 924             ActorSelection leader = getLeader();
 925             if (leader != null) {
 926                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
 927
 928                 if (!messagesToForward.isEmpty()) {
 929                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
 930                             messagesToForward.size(), leader);
 931
 932                     for (Object message : messagesToForward) {
 933                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
 934
 935                         leader.tell(message, self());
 936                     }
 937                 }
 938             } else {
 939                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
 940                         + "change and the leader address isn't available.", this);
 941             }
 942         } else {
 943             // We have become the leader, we need to reconstruct frontend state
 944             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 945             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
 946         }
 947
 948         if (!isIsolatedLeader()) {
 949             messageRetrySupport.retryMessages();
 950         }
 951     }
 952
 953     /**
 954      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
 955      *
 956      * @return the converted messages
 957      */
 958     public Collection<?> convertPendingTransactionsToMessages() {
 959         return commitCoordinator.convertPendingTransactionsToMessages(
 960                 datastoreContext.getShardBatchedModificationCount());
 961     }
 962
 963     @Override
 964     protected void pauseLeader(final Runnable operation) {
 965         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
 966         paused = true;
 967
 968         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
 969         knownFrontends.values().forEach(LeaderFrontendState::retire);
 970         knownFrontends = ImmutableMap.of();
 971
 972         store.setRunOnPendingTransactionsComplete(operation);
 973     }
 974
 975     @Override
 976     protected void unpauseLeader() {
 977         LOG.debug("{}: In unpauseLeader", persistenceId());
 978         paused = false;
 979
 980         store.setRunOnPendingTransactionsComplete(null);
 981
 982         // Restore tell-based protocol state as if we were becoming the leader
 983         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 984     }
 985
 986     @Override
 987     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
 988         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
 989                 .commitCohortActors(store.getCohortActors());
 990     }
 991
 992     @Override
 993     public String persistenceId() {
 994         return this.name;
 995     }
 996
 997     @VisibleForTesting
 998     ShardCommitCoordinator getCommitCoordinator() {
 999         return commitCoordinator;
1000     }
1001
1002     public DatastoreContext getDatastoreContext() {
1003         return datastoreContext;
1004     }
1005
1006     @VisibleForTesting
1007     public ShardDataTree getDataStore() {
1008         return store;
1009     }
1010
1011     @VisibleForTesting
1012     ShardStats getShardMBean() {
1013         return shardMBean;
1014     }
1015
1016     public static Builder builder() {
1017         return new Builder();
1018     }
1019
1020     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1021         private final Class<S> shardClass;
1022         private ShardIdentifier id;
1023         private Map<String, String> peerAddresses = Collections.emptyMap();
1024         private DatastoreContext datastoreContext;
1025         private SchemaContextProvider schemaContextProvider;
1026         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1027         private DataTree dataTree;
1028         private volatile boolean sealed;
1029
1030         protected AbstractBuilder(final Class<S> shardClass) {
1031             this.shardClass = shardClass;
1032         }
1033
1034         protected void checkSealed() {
1035             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1036         }
1037
1038         @SuppressWarnings("unchecked")
1039         private T self() {
1040             return (T) this;
1041         }
1042
1043         public T id(final ShardIdentifier newId) {
1044             checkSealed();
1045             this.id = newId;
1046             return self();
1047         }
1048
1049         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1050             checkSealed();
1051             this.peerAddresses = newPeerAddresses;
1052             return self();
1053         }
1054
1055         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1056             checkSealed();
1057             this.datastoreContext = newDatastoreContext;
1058             return self();
1059         }
1060
1061         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1062             checkSealed();
1063             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1064             return self();
1065         }
1066
1067         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1068             checkSealed();
1069             this.restoreFromSnapshot = newRestoreFromSnapshot;
1070             return self();
1071         }
1072
1073         public T dataTree(final DataTree newDataTree) {
1074             checkSealed();
1075             this.dataTree = newDataTree;
1076             return self();
1077         }
1078
1079         public ShardIdentifier getId() {
1080             return id;
1081         }
1082
1083         public Map<String, String> getPeerAddresses() {
1084             return peerAddresses;
1085         }
1086
1087         public DatastoreContext getDatastoreContext() {
1088             return datastoreContext;
1089         }
1090
1091         public SchemaContext getSchemaContext() {
1092             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1093         }
1094
1095         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1096             return restoreFromSnapshot;
1097         }
1098
1099         public DataTree getDataTree() {
1100             return dataTree;
1101         }
1102
1103         public TreeType getTreeType() {
1104             switch (datastoreContext.getLogicalStoreType()) {
1105                 case CONFIGURATION:
1106                     return TreeType.CONFIGURATION;
1107                 case OPERATIONAL:
1108                     return TreeType.OPERATIONAL;
1109                 default:
1110                     throw new IllegalStateException("Unhandled logical store type "
1111                             + datastoreContext.getLogicalStoreType());
1112             }
1113         }
1114
1115         protected void verify() {
1116             Preconditions.checkNotNull(id, "id should not be null");
1117             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1118             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1119             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1120         }
1121
1122         public Props props() {
1123             sealed = true;
1124             verify();
1125             return Props.create(shardClass, this);
1126         }
1127     }
1128
1129     public static class Builder extends AbstractBuilder<Builder, Shard> {
1130         Builder() {
1131             super(Shard.class);
1132         }
1133     }
1134
1135     Ticker ticker() {
1136         return Ticker.systemTicker();
1137     }
1138
1139     void scheduleNextPendingTransaction() {
1140         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1141     }
1142 }