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 package org.opendaylight.controller.cluster.datastore;
   9
  10 import akka.actor.ActorRef;
  11 import akka.actor.ActorSelection;
  12 import akka.actor.Cancellable;
  13 import akka.actor.ExtendedActorSystem;
  14 import akka.actor.Props;
  15 import akka.actor.Status;
  16 import akka.actor.Status.Failure;
  17 import akka.serialization.JavaSerializer;
  18 import akka.serialization.Serialization;
  19 import com.google.common.annotations.VisibleForTesting;
  20 import com.google.common.base.Optional;
  21 import com.google.common.base.Preconditions;
  22 import com.google.common.base.Ticker;
  23 import com.google.common.base.Verify;
  24 import com.google.common.collect.ImmutableList;
  25 import com.google.common.collect.ImmutableMap;
  26 import com.google.common.collect.Range;
  27 import java.io.IOException;
  28 import java.util.Arrays;
  29 import java.util.Collection;
  30 import java.util.Collections;
  31 import java.util.Map;
  32 import java.util.concurrent.TimeUnit;
  33 import org.eclipse.jdt.annotation.NonNull;
  34 import org.eclipse.jdt.annotation.Nullable;
  35 import org.opendaylight.controller.cluster.access.ABIVersion;
  36 import org.opendaylight.controller.cluster.access.commands.ConnectClientRequest;
  37 import org.opendaylight.controller.cluster.access.commands.ConnectClientSuccess;
  38 import org.opendaylight.controller.cluster.access.commands.LocalHistoryRequest;
  39 import org.opendaylight.controller.cluster.access.commands.NotLeaderException;
  40 import org.opendaylight.controller.cluster.access.commands.OutOfSequenceEnvelopeException;
  41 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
  42 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  43 import org.opendaylight.controller.cluster.access.concepts.FrontendIdentifier;
  44 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
  45 import org.opendaylight.controller.cluster.access.concepts.Request;
  46 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
  47 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  48 import org.opendaylight.controller.cluster.access.concepts.RequestSuccess;
  49 import org.opendaylight.controller.cluster.access.concepts.RetiredGenerationException;
  50 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
  51 import org.opendaylight.controller.cluster.access.concepts.SliceableMessage;
  52 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  53 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
  54 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
  55 import org.opendaylight.controller.cluster.common.actor.Dispatchers;
  56 import org.opendaylight.controller.cluster.common.actor.Dispatchers.DispatcherType;
  57 import org.opendaylight.controller.cluster.common.actor.MessageTracker;
  58 import org.opendaylight.controller.cluster.common.actor.MessageTracker.Error;
  59 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
  60 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  61 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  62 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardDataTreeListenerInfoMXBeanImpl;
  63 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardMBeanFactory;
  64 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
  65 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
  66 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
  67 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  68 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransaction;
  69 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  70 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
  71 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  72 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  73 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
  74 import org.opendaylight.controller.cluster.datastore.messages.GetShardDataTree;
  75 import org.opendaylight.controller.cluster.datastore.messages.MakeLeaderLocal;
  76 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
  77 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
  78 import org.opendaylight.controller.cluster.datastore.messages.PersistAbortTransactionPayload;
  79 import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
  80 import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
  81 import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
  82 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
  83 import org.opendaylight.controller.cluster.datastore.persisted.AbortTransactionPayload;
  84 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot;
  85 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot.ShardSnapshot;
  86 import org.opendaylight.controller.cluster.messaging.MessageAssembler;
  87 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
  88 import org.opendaylight.controller.cluster.messaging.SliceOptions;
  89 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
  90 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
  91 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
  92 import org.opendaylight.controller.cluster.raft.LeadershipTransferFailedException;
  93 import org.opendaylight.controller.cluster.raft.RaftActor;
  94 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
  95 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
  96 import org.opendaylight.controller.cluster.raft.RaftState;
  97 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
  98 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
  99 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
 100 import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
 101 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
 102 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
 103 import org.opendaylight.yangtools.concepts.Identifier;
 104 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
 105 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
 106 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
 107 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
 108 import org.opendaylight.yangtools.yang.model.api.SchemaContextProvider;
 109 import scala.concurrent.duration.FiniteDuration;
 110
 111 /**
 112  * A Shard represents a portion of the logical data tree.
 113  *
 114  * <p>
 115  * Our Shard uses InMemoryDataTree as it's internal representation and delegates all requests it
 116  */
 117 public class Shard extends RaftActor {
 118
 119     @VisibleForTesting
 120     static final Object TX_COMMIT_TIMEOUT_CHECK_MESSAGE = new Object() {
 121         @Override
 122         public String toString() {
 123             return "txCommitTimeoutCheck";
 124         }
 125     };
 126
 127     @VisibleForTesting
 128     static final Object GET_SHARD_MBEAN_MESSAGE = new Object() {
 129         @Override
 130         public String toString() {
 131             return "getShardMBeanMessage";
 132         }
 133     };
 134
 135     static final Object RESUME_NEXT_PENDING_TRANSACTION = new Object() {
 136         @Override
 137         public String toString() {
 138             return "resumeNextPendingTransaction";
 139         }
 140     };
 141
 142     // FIXME: shard names should be encapsulated in their own class and this should be exposed as a constant.
 143     public static final String DEFAULT_NAME = "default";
 144
 145     private static final Collection<ABIVersion> SUPPORTED_ABIVERSIONS;
 146
 147     static {
 148         final ABIVersion[] values = ABIVersion.values();
 149         final ABIVersion[] real = Arrays.copyOfRange(values, 1, values.length - 1);
 150         SUPPORTED_ABIVERSIONS = ImmutableList.copyOf(real).reverse();
 151     }
 152
 153     // FIXME: make this a dynamic property based on mailbox size and maximum number of clients
 154     private static final int CLIENT_MAX_MESSAGES = 1000;
 155
 156     // The state of this Shard
 157     private final ShardDataTree store;
 158
 159     /// The name of this shard
 160     private final String name;
 161
 162     private final String shardName;
 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.shardName = builder.getId().getShardName();
 205         this.datastoreContext = builder.getDatastoreContext();
 206         this.restoreFromSnapshot = builder.getRestoreFromSnapshot();
 207         this.frontendMetadata = new FrontendMetadata(name);
 208
 209         setPersistence(datastoreContext.isPersistent());
 210
 211         LOG.info("Shard created : {}, persistent : {}", name, datastoreContext.isPersistent());
 212
 213         ShardDataTreeChangeListenerPublisherActorProxy treeChangeListenerPublisher =
 214                 new ShardDataTreeChangeListenerPublisherActorProxy(getContext(), name + "-DTCL-publisher", name);
 215         if (builder.getDataTree() != null) {
 216             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getDataTree(),
 217                     treeChangeListenerPublisher, name, frontendMetadata);
 218         } else {
 219             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getTreeType(),
 220                     builder.getDatastoreContext().getStoreRoot(), treeChangeListenerPublisher, name, frontendMetadata);
 221         }
 222
 223         shardMBean = ShardMBeanFactory.getShardStatsMBean(name, datastoreContext.getDataStoreMXBeanType(), this);
 224
 225         if (isMetricsCaptureEnabled()) {
 226             getContext().become(new MeteringBehavior(this));
 227         }
 228
 229         commitCoordinator = new ShardCommitCoordinator(store, LOG, this.name);
 230
 231         setTransactionCommitTimeout();
 232
 233         // create a notifier actor for each cluster member
 234         roleChangeNotifier = createRoleChangeNotifier(name);
 235
 236         appendEntriesReplyTracker = new MessageTracker(AppendEntriesReply.class,
 237                 getRaftActorContext().getConfigParams().getIsolatedCheckIntervalInMillis());
 238
 239         dispatchers = new Dispatchers(context().system().dispatchers());
 240         transactionActorFactory = new ShardTransactionActorFactory(store, datastoreContext,
 241             dispatchers.getDispatcherPath(Dispatchers.DispatcherType.Transaction),
 242                 self(), getContext(), shardMBean, builder.getId().getShardName());
 243
 244         snapshotCohort = ShardSnapshotCohort.create(getContext(), builder.getId().getMemberName(), store, LOG,
 245             this.name);
 246
 247         messageRetrySupport = new ShardTransactionMessageRetrySupport(this);
 248
 249         responseMessageSlicer = MessageSlicer.builder().logContext(this.name)
 250                 .messageSliceSize(datastoreContext.getMaximumMessageSliceSize())
 251                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 252                 .expireStateAfterInactivity(2, TimeUnit.MINUTES).build();
 253
 254         requestMessageAssembler = MessageAssembler.builder().logContext(this.name)
 255                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 256                 .assembledMessageCallback((message, sender) -> self().tell(message, sender))
 257                 .expireStateAfterInactivity(datastoreContext.getRequestTimeout(), TimeUnit.NANOSECONDS).build();
 258
 259         listenerInfoMXBean = new ShardDataTreeListenerInfoMXBeanImpl(name, datastoreContext.getDataStoreMXBeanType(),
 260                 self());
 261         listenerInfoMXBean.register();
 262     }
 263
 264     private void setTransactionCommitTimeout() {
 265         transactionCommitTimeout = TimeUnit.MILLISECONDS.convert(
 266                 datastoreContext.getShardTransactionCommitTimeoutInSeconds(), TimeUnit.SECONDS) / 2;
 267     }
 268
 269     private Optional<ActorRef> createRoleChangeNotifier(final String shardId) {
 270         ActorRef shardRoleChangeNotifier = this.getContext().actorOf(
 271             RoleChangeNotifier.getProps(shardId), shardId + "-notifier");
 272         return Optional.of(shardRoleChangeNotifier);
 273     }
 274
 275     @Override
 276     public void postStop() {
 277         LOG.info("Stopping Shard {}", persistenceId());
 278
 279         super.postStop();
 280
 281         messageRetrySupport.close();
 282
 283         if (txCommitTimeoutCheckSchedule != null) {
 284             txCommitTimeoutCheckSchedule.cancel();
 285         }
 286
 287         commitCoordinator.abortPendingTransactions("Transaction aborted due to shutdown.", this);
 288
 289         shardMBean.unregisterMBean();
 290         listenerInfoMXBean.unregister();
 291     }
 292
 293     @Override
 294     protected void handleRecover(final Object message) {
 295         LOG.debug("{}: onReceiveRecover: Received message {} from {}", persistenceId(), message.getClass(),
 296             getSender());
 297
 298         super.handleRecover(message);
 299         if (LOG.isTraceEnabled()) {
 300             appendEntriesReplyTracker.begin();
 301         }
 302     }
 303
 304     @Override
 305     protected void handleNonRaftCommand(final Object message) {
 306         try (MessageTracker.Context context = appendEntriesReplyTracker.received(message)) {
 307             final Optional<Error> maybeError = context.error();
 308             if (maybeError.isPresent()) {
 309                 LOG.trace("{} : AppendEntriesReply failed to arrive at the expected interval {}", persistenceId(),
 310                     maybeError.get());
 311             }
 312
 313             store.resetTransactionBatch();
 314
 315             if (message instanceof RequestEnvelope) {
 316                 handleRequestEnvelope((RequestEnvelope)message);
 317             } else if (MessageAssembler.isHandledMessage(message)) {
 318                 handleRequestAssemblerMessage(message);
 319             } else if (message instanceof ConnectClientRequest) {
 320                 handleConnectClient((ConnectClientRequest)message);
 321             } else if (CreateTransaction.isSerializedType(message)) {
 322                 handleCreateTransaction(message);
 323             } else if (message instanceof BatchedModifications) {
 324                 handleBatchedModifications((BatchedModifications)message);
 325             } else if (message instanceof ForwardedReadyTransaction) {
 326                 handleForwardedReadyTransaction((ForwardedReadyTransaction) message);
 327             } else if (message instanceof ReadyLocalTransaction) {
 328                 handleReadyLocalTransaction((ReadyLocalTransaction)message);
 329             } else if (CanCommitTransaction.isSerializedType(message)) {
 330                 handleCanCommitTransaction(CanCommitTransaction.fromSerializable(message));
 331             } else if (CommitTransaction.isSerializedType(message)) {
 332                 handleCommitTransaction(CommitTransaction.fromSerializable(message));
 333             } else if (AbortTransaction.isSerializedType(message)) {
 334                 handleAbortTransaction(AbortTransaction.fromSerializable(message));
 335             } else if (CloseTransactionChain.isSerializedType(message)) {
 336                 closeTransactionChain(CloseTransactionChain.fromSerializable(message));
 337             } else if (message instanceof RegisterDataTreeChangeListener) {
 338                 treeChangeSupport.onMessage((RegisterDataTreeChangeListener) message, isLeader(), hasLeader());
 339             } else if (message instanceof UpdateSchemaContext) {
 340                 updateSchemaContext((UpdateSchemaContext) message);
 341             } else if (message instanceof PeerAddressResolved) {
 342                 PeerAddressResolved resolved = (PeerAddressResolved) message;
 343                 setPeerAddress(resolved.getPeerId(), resolved.getPeerAddress());
 344             } else if (TX_COMMIT_TIMEOUT_CHECK_MESSAGE.equals(message)) {
 345                 commitTimeoutCheck();
 346             } else if (message instanceof DatastoreContext) {
 347                 onDatastoreContext((DatastoreContext)message);
 348             } else if (message instanceof RegisterRoleChangeListener) {
 349                 roleChangeNotifier.get().forward(message, context());
 350             } else if (message instanceof FollowerInitialSyncUpStatus) {
 351                 shardMBean.setFollowerInitialSyncStatus(((FollowerInitialSyncUpStatus) message).isInitialSyncDone());
 352                 context().parent().tell(message, self());
 353             } else if (GET_SHARD_MBEAN_MESSAGE.equals(message)) {
 354                 sender().tell(getShardMBean(), self());
 355             } else if (message instanceof GetShardDataTree) {
 356                 sender().tell(store.getDataTree(), self());
 357             } else if (message instanceof ServerRemoved) {
 358                 context().parent().forward(message, context());
 359             } else if (ShardTransactionMessageRetrySupport.TIMER_MESSAGE_CLASS.isInstance(message)) {
 360                 messageRetrySupport.onTimerMessage(message);
 361             } else if (message instanceof DataTreeCohortActorRegistry.CohortRegistryCommand) {
 362                 store.processCohortRegistryCommand(getSender(),
 363                         (DataTreeCohortActorRegistry.CohortRegistryCommand) message);
 364             } else if (message instanceof PersistAbortTransactionPayload) {
 365                 final TransactionIdentifier txId = ((PersistAbortTransactionPayload) message).getTransactionId();
 366                 persistPayload(txId, AbortTransactionPayload.create(
 367                         txId, datastoreContext.getInitialPayloadSerializedBufferCapacity()), true);
 368                 store.purgeTransaction(txId, null);
 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     private @Nullable 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(clientId.getGeneration(),
 475                     existing.getIdentifier().getGeneration());
 476             }
 477
 478             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 479             existing.retire();
 480             knownFrontends.remove(clientId.getFrontendId());
 481         } else {
 482             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 483         }
 484
 485         return null;
 486     }
 487
 488     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 489         final LeaderFrontendState ret = findFrontend(clientId);
 490         if (ret != null) {
 491             return ret;
 492         }
 493
 494         // TODO: a dedicated exception would be better, but this is technically true, too
 495         throw new OutOfSequenceEnvelopeException(0);
 496     }
 497
 498     private static @NonNull 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     private @Nullable RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 547             throws RequestException {
 548         // We are not the leader, hence we want to fail-fast.
 549         if (!isLeader() || paused || !isLeaderActive()) {
 550             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 551                             + "isLeadershipTransferInProgress: {}, paused: {}",
 552                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 553             throw new NotLeaderException(getSelf());
 554         }
 555
 556         final Request<?, ?> request = envelope.getMessage();
 557         if (request instanceof TransactionRequest) {
 558             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
 559             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
 560             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 561         } else if (request instanceof LocalHistoryRequest) {
 562             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
 563             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
 564             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 565         } else {
 566             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 567             throw new UnsupportedRequestException(request);
 568         }
 569     }
 570
 571     private boolean hasLeader() {
 572         return getLeaderId() != null;
 573     }
 574
 575     public int getPendingTxCommitQueueSize() {
 576         return store.getQueueSize();
 577     }
 578
 579     public int getCohortCacheSize() {
 580         return commitCoordinator.getCohortCacheSize();
 581     }
 582
 583     @Override
 584     protected Optional<ActorRef> getRoleChangeNotifier() {
 585         return roleChangeNotifier;
 586     }
 587
 588     String getShardName() {
 589         return shardName;
 590     }
 591
 592     @Override
 593     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 594             final short leaderPayloadVersion) {
 595         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 596                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 597     }
 598
 599     protected void onDatastoreContext(final DatastoreContext context) {
 600         datastoreContext = context;
 601
 602         setTransactionCommitTimeout();
 603
 604         setPersistence(datastoreContext.isPersistent());
 605
 606         updateConfigParams(datastoreContext.getShardRaftConfig());
 607     }
 608
 609     // applyState() will be invoked once consensus is reached on the payload
 610     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 611         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 612         if (canSkipPayload) {
 613             applyState(self(), id, payload);
 614         } else {
 615             // We are faking the sender
 616             persistData(self(), id, payload, batchHint);
 617         }
 618     }
 619
 620     private void handleCommitTransaction(final CommitTransaction commit) {
 621         if (isLeader()) {
 622             commitCoordinator.handleCommit(commit.getTransactionId(), getSender(), this);
 623         } else {
 624             ActorSelection leader = getLeader();
 625             if (leader == null) {
 626                 messageRetrySupport.addMessageToRetry(commit, getSender(),
 627                         "Could not commit transaction " + commit.getTransactionId());
 628             } else {
 629                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 630                 leader.forward(commit, getContext());
 631             }
 632         }
 633     }
 634
 635     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 636         LOG.debug("{}: Can committing transaction {}", persistenceId(), canCommit.getTransactionId());
 637
 638         if (isLeader()) {
 639             commitCoordinator.handleCanCommit(canCommit.getTransactionId(), getSender(), this);
 640         } else {
 641             ActorSelection leader = getLeader();
 642             if (leader == null) {
 643                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 644                         "Could not canCommit transaction " + canCommit.getTransactionId());
 645             } else {
 646                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 647                 leader.forward(canCommit, getContext());
 648             }
 649         }
 650     }
 651
 652     @SuppressWarnings("checkstyle:IllegalCatch")
 653     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 654         try {
 655             commitCoordinator.handleBatchedModifications(batched, sender, this);
 656         } catch (Exception e) {
 657             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 658                     batched.getTransactionId(), e);
 659             sender.tell(new Failure(e), getSelf());
 660         }
 661     }
 662
 663     private void handleBatchedModifications(final BatchedModifications batched) {
 664         // This message is sent to prepare the modifications transaction directly on the Shard as an
 665         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 666         // BatchedModifications message, the caller sets the ready flag in the message indicating
 667         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 668         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 669         // ReadyTransaction message.
 670
 671         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 672         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 673         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 674         // window where it could have a stale leader during leadership transitions.
 675         //
 676         boolean isLeaderActive = isLeaderActive();
 677         if (isLeader() && isLeaderActive) {
 678             handleBatchedModificationsLocal(batched, getSender());
 679         } else {
 680             ActorSelection leader = getLeader();
 681             if (!isLeaderActive || leader == null) {
 682                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 683                         "Could not process BatchedModifications " + batched.getTransactionId());
 684             } else {
 685                 // If this is not the first batch and leadership changed in between batched messages,
 686                 // we need to reconstruct previous BatchedModifications from the transaction
 687                 // DataTreeModification, honoring the max batched modification count, and forward all the
 688                 // previous BatchedModifications to the new leader.
 689                 Collection<BatchedModifications> newModifications = commitCoordinator
 690                         .createForwardedBatchedModifications(batched,
 691                                 datastoreContext.getShardBatchedModificationCount());
 692
 693                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 694                         newModifications.size(), leader);
 695
 696                 for (BatchedModifications bm : newModifications) {
 697                     leader.forward(bm, getContext());
 698                 }
 699             }
 700         }
 701     }
 702
 703     private boolean failIfIsolatedLeader(final ActorRef sender) {
 704         if (isIsolatedLeader()) {
 705             sender.tell(new Failure(new NoShardLeaderException(String.format(
 706                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 707                     + " other follower nodes are down or this node is isolated by a network partition.",
 708                     persistenceId()))), getSelf());
 709             return true;
 710         }
 711
 712         return false;
 713     }
 714
 715     protected boolean isIsolatedLeader() {
 716         return getRaftState() == RaftState.IsolatedLeader;
 717     }
 718
 719     @SuppressWarnings("checkstyle:IllegalCatch")
 720     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 721         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
 722
 723         boolean isLeaderActive = isLeaderActive();
 724         if (isLeader() && isLeaderActive) {
 725             try {
 726                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 727             } catch (Exception e) {
 728                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
 729                         message.getTransactionId(), e);
 730                 getSender().tell(new Failure(e), getSelf());
 731             }
 732         } else {
 733             ActorSelection leader = getLeader();
 734             if (!isLeaderActive || leader == null) {
 735                 messageRetrySupport.addMessageToRetry(message, getSender(),
 736                         "Could not process ready local transaction " + message.getTransactionId());
 737             } else {
 738                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 739                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 740                 leader.forward(message, getContext());
 741             }
 742         }
 743     }
 744
 745     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 746         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 747
 748         boolean isLeaderActive = isLeaderActive();
 749         if (isLeader() && isLeaderActive) {
 750             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 751         } else {
 752             ActorSelection leader = getLeader();
 753             if (!isLeaderActive || leader == null) {
 754                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 755                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 756             } else {
 757                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 758
 759                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 760                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 761                         forwardedReady.getParticipatingShardNames());
 762                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 763                 leader.forward(readyLocal, getContext());
 764             }
 765         }
 766     }
 767
 768     private void handleAbortTransaction(final AbortTransaction abort) {
 769         doAbortTransaction(abort.getTransactionId(), getSender());
 770     }
 771
 772     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 773         commitCoordinator.handleAbort(transactionID, sender, this);
 774     }
 775
 776     private void handleCreateTransaction(final Object message) {
 777         if (isLeader()) {
 778             createTransaction(CreateTransaction.fromSerializable(message));
 779         } else if (getLeader() != null) {
 780             getLeader().forward(message, getContext());
 781         } else {
 782             getSender().tell(new Failure(new NoShardLeaderException(
 783                     "Could not create a shard transaction", persistenceId())), getSelf());
 784         }
 785     }
 786
 787     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 788         if (isLeader()) {
 789             final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 790             // FIXME: CONTROLLER-1628: stage purge once no transactions are present
 791             store.closeTransactionChain(id, null);
 792             store.purgeTransactionChain(id, null);
 793         } else if (getLeader() != null) {
 794             getLeader().forward(closeTransactionChain, getContext());
 795         } else {
 796             LOG.warn("{}: Could not close transaction {}", persistenceId(), closeTransactionChain.getIdentifier());
 797         }
 798     }
 799
 800     @SuppressWarnings("checkstyle:IllegalCatch")
 801     private void createTransaction(final CreateTransaction createTransaction) {
 802         try {
 803             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
 804                     && failIfIsolatedLeader(getSender())) {
 805                 return;
 806             }
 807
 808             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 809                 createTransaction.getTransactionId());
 810
 811             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 812                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 813         } catch (Exception e) {
 814             getSender().tell(new Failure(e), getSelf());
 815         }
 816     }
 817
 818     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
 819         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 820         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 821             transactionId);
 822     }
 823
 824     private void updateSchemaContext(final UpdateSchemaContext message) {
 825         updateSchemaContext(message.getSchemaContext());
 826     }
 827
 828     @VisibleForTesting
 829     void updateSchemaContext(final SchemaContext schemaContext) {
 830         store.updateSchemaContext(schemaContext);
 831     }
 832
 833     private boolean isMetricsCaptureEnabled() {
 834         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 835         return config.isMetricCaptureEnabled();
 836     }
 837
 838     @Override
 839     @VisibleForTesting
 840     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 841         return snapshotCohort;
 842     }
 843
 844     @Override
 845     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 846         if (restoreFromSnapshot == null) {
 847             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 848         }
 849
 850         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 851     }
 852
 853     @Override
 854     protected void onRecoveryComplete() {
 855         restoreFromSnapshot = null;
 856
 857         //notify shard manager
 858         getContext().parent().tell(new ActorInitialized(), getSelf());
 859
 860         // Being paranoid here - this method should only be called once but just in case...
 861         if (txCommitTimeoutCheckSchedule == null) {
 862             // Schedule a message to be periodically sent to check if the current in-progress
 863             // transaction should be expired and aborted.
 864             FiniteDuration period = FiniteDuration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 865             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 866                     period, period, getSelf(),
 867                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 868         }
 869     }
 870
 871     @Override
 872     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 873         if (data instanceof Payload) {
 874             try {
 875                 store.applyReplicatedPayload(identifier, (Payload)data);
 876             } catch (DataValidationFailedException | IOException e) {
 877                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 878             }
 879         } else {
 880             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
 881         }
 882     }
 883
 884     @Override
 885     protected void onStateChanged() {
 886         boolean isLeader = isLeader();
 887         boolean hasLeader = hasLeader();
 888         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
 889
 890         // If this actor is no longer the leader close all the transaction chains
 891         if (!isLeader) {
 892             if (LOG.isDebugEnabled()) {
 893                 LOG.debug(
 894                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
 895                     persistenceId(), getId());
 896             }
 897
 898             paused = false;
 899             store.purgeLeaderState();
 900         }
 901
 902         if (hasLeader && !isIsolatedLeader()) {
 903             messageRetrySupport.retryMessages();
 904         }
 905     }
 906
 907     @Override
 908     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
 909         shardMBean.incrementLeadershipChangeCount();
 910         paused = false;
 911
 912         if (!isLeader()) {
 913             if (!knownFrontends.isEmpty()) {
 914                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
 915                 knownFrontends = ImmutableMap.of();
 916             }
 917
 918             requestMessageAssembler.close();
 919
 920             if (!hasLeader()) {
 921                 // No leader anywhere, nothing else to do
 922                 return;
 923             }
 924
 925             // Another leader was elected. If we were the previous leader and had pending transactions, convert
 926             // them to transaction messages and send to the new leader.
 927             ActorSelection leader = getLeader();
 928             if (leader != null) {
 929                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
 930
 931                 if (!messagesToForward.isEmpty()) {
 932                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
 933                             messagesToForward.size(), leader);
 934
 935                     for (Object message : messagesToForward) {
 936                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
 937
 938                         leader.tell(message, self());
 939                     }
 940                 }
 941             } else {
 942                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
 943                         + "change and the leader address isn't available.", this);
 944             }
 945         } else {
 946             // We have become the leader, we need to reconstruct frontend state
 947             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 948             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
 949         }
 950
 951         if (!isIsolatedLeader()) {
 952             messageRetrySupport.retryMessages();
 953         }
 954     }
 955
 956     /**
 957      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
 958      *
 959      * @return the converted messages
 960      */
 961     public Collection<?> convertPendingTransactionsToMessages() {
 962         return commitCoordinator.convertPendingTransactionsToMessages(
 963                 datastoreContext.getShardBatchedModificationCount());
 964     }
 965
 966     @Override
 967     protected void pauseLeader(final Runnable operation) {
 968         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
 969         paused = true;
 970
 971         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
 972         knownFrontends.values().forEach(LeaderFrontendState::retire);
 973         knownFrontends = ImmutableMap.of();
 974
 975         store.setRunOnPendingTransactionsComplete(operation);
 976     }
 977
 978     @Override
 979     protected void unpauseLeader() {
 980         LOG.debug("{}: In unpauseLeader", persistenceId());
 981         paused = false;
 982
 983         store.setRunOnPendingTransactionsComplete(null);
 984
 985         // Restore tell-based protocol state as if we were becoming the leader
 986         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 987     }
 988
 989     @Override
 990     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
 991         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
 992                 .commitCohortActors(store.getCohortActors());
 993     }
 994
 995     @Override
 996     public String persistenceId() {
 997         return this.name;
 998     }
 999
1000     @VisibleForTesting
1001     ShardCommitCoordinator getCommitCoordinator() {
1002         return commitCoordinator;
1003     }
1004
1005     public DatastoreContext getDatastoreContext() {
1006         return datastoreContext;
1007     }
1008
1009     @VisibleForTesting
1010     public ShardDataTree getDataStore() {
1011         return store;
1012     }
1013
1014     @VisibleForTesting
1015     ShardStats getShardMBean() {
1016         return shardMBean;
1017     }
1018
1019     public static Builder builder() {
1020         return new Builder();
1021     }
1022
1023     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1024         private final Class<S> shardClass;
1025         private ShardIdentifier id;
1026         private Map<String, String> peerAddresses = Collections.emptyMap();
1027         private DatastoreContext datastoreContext;
1028         private SchemaContextProvider schemaContextProvider;
1029         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1030         private DataTree dataTree;
1031         private volatile boolean sealed;
1032
1033         protected AbstractBuilder(final Class<S> shardClass) {
1034             this.shardClass = shardClass;
1035         }
1036
1037         protected void checkSealed() {
1038             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1039         }
1040
1041         @SuppressWarnings("unchecked")
1042         private T self() {
1043             return (T) this;
1044         }
1045
1046         public T id(final ShardIdentifier newId) {
1047             checkSealed();
1048             this.id = newId;
1049             return self();
1050         }
1051
1052         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1053             checkSealed();
1054             this.peerAddresses = newPeerAddresses;
1055             return self();
1056         }
1057
1058         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1059             checkSealed();
1060             this.datastoreContext = newDatastoreContext;
1061             return self();
1062         }
1063
1064         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1065             checkSealed();
1066             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1067             return self();
1068         }
1069
1070         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1071             checkSealed();
1072             this.restoreFromSnapshot = newRestoreFromSnapshot;
1073             return self();
1074         }
1075
1076         public T dataTree(final DataTree newDataTree) {
1077             checkSealed();
1078             this.dataTree = newDataTree;
1079             return self();
1080         }
1081
1082         public ShardIdentifier getId() {
1083             return id;
1084         }
1085
1086         public Map<String, String> getPeerAddresses() {
1087             return peerAddresses;
1088         }
1089
1090         public DatastoreContext getDatastoreContext() {
1091             return datastoreContext;
1092         }
1093
1094         public SchemaContext getSchemaContext() {
1095             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1096         }
1097
1098         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1099             return restoreFromSnapshot;
1100         }
1101
1102         public DataTree getDataTree() {
1103             return dataTree;
1104         }
1105
1106         public TreeType getTreeType() {
1107             switch (datastoreContext.getLogicalStoreType()) {
1108                 case CONFIGURATION:
1109                     return TreeType.CONFIGURATION;
1110                 case OPERATIONAL:
1111                     return TreeType.OPERATIONAL;
1112                 default:
1113                     throw new IllegalStateException("Unhandled logical store type "
1114                             + datastoreContext.getLogicalStoreType());
1115             }
1116         }
1117
1118         protected void verify() {
1119             Preconditions.checkNotNull(id, "id should not be null");
1120             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1121             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1122             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1123         }
1124
1125         public Props props() {
1126             sealed = true;
1127             verify();
1128             return Props.create(shardClass, this);
1129         }
1130     }
1131
1132     public static class Builder extends AbstractBuilder<Builder, Shard> {
1133         Builder() {
1134             super(Shard.class);
1135         }
1136     }
1137
1138     Ticker ticker() {
1139         return Ticker.systemTicker();
1140     }
1141
1142     void scheduleNextPendingTransaction() {
1143         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1144     }
1145 }