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