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.datastore.persisted.PurgeTransactionPayload;
  88 import org.opendaylight.controller.cluster.messaging.MessageAssembler;
  89 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
  90 import org.opendaylight.controller.cluster.messaging.SliceOptions;
  91 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
  92 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
  93 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
  94 import org.opendaylight.controller.cluster.raft.LeadershipTransferFailedException;
  95 import org.opendaylight.controller.cluster.raft.RaftActor;
  96 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
  97 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
  98 import org.opendaylight.controller.cluster.raft.RaftState;
  99 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
 100 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
 101 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
 102 import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
 103 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
 104 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
 105 import org.opendaylight.yangtools.concepts.Identifier;
 106 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
 107 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
 108 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
 109 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
 110 import org.opendaylight.yangtools.yang.model.api.SchemaContextProvider;
 111 import scala.concurrent.duration.Duration;
 112 import scala.concurrent.duration.FiniteDuration;
 113
 114 /**
 115  * A Shard represents a portion of the logical data tree.
 116  *
 117  * <p>
 118  * Our Shard uses InMemoryDataTree as it's internal representation and delegates all requests it
 119  */
 120 public class Shard extends RaftActor {
 121
 122     @VisibleForTesting
 123     static final Object TX_COMMIT_TIMEOUT_CHECK_MESSAGE = new Object() {
 124         @Override
 125         public String toString() {
 126             return "txCommitTimeoutCheck";
 127         }
 128     };
 129
 130     @VisibleForTesting
 131     static final Object GET_SHARD_MBEAN_MESSAGE = new Object() {
 132         @Override
 133         public String toString() {
 134             return "getShardMBeanMessage";
 135         }
 136     };
 137
 138     static final Object RESUME_NEXT_PENDING_TRANSACTION = new Object() {
 139         @Override
 140         public String toString() {
 141             return "resumeNextPendingTransaction";
 142         }
 143     };
 144
 145     // FIXME: shard names should be encapsulated in their own class and this should be exposed as a constant.
 146     public static final String DEFAULT_NAME = "default";
 147
 148     private static final Collection<ABIVersion> SUPPORTED_ABIVERSIONS;
 149
 150     static {
 151         final ABIVersion[] values = ABIVersion.values();
 152         final ABIVersion[] real = Arrays.copyOfRange(values, 1, values.length - 1);
 153         SUPPORTED_ABIVERSIONS = ImmutableList.copyOf(real).reverse();
 154     }
 155
 156     // FIXME: make this a dynamic property based on mailbox size and maximum number of clients
 157     private static final int CLIENT_MAX_MESSAGES = 1000;
 158
 159     // The state of this Shard
 160     private final ShardDataTree store;
 161
 162     /// The name of this shard
 163     private final String name;
 164
 165     private final String shardName;
 166
 167     private final ShardStats shardMBean;
 168
 169     private final ShardDataTreeListenerInfoMXBeanImpl listenerInfoMXBean;
 170
 171     private DatastoreContext datastoreContext;
 172
 173     private final ShardCommitCoordinator commitCoordinator;
 174
 175     private long transactionCommitTimeout;
 176
 177     private Cancellable txCommitTimeoutCheckSchedule;
 178
 179     private final Optional<ActorRef> roleChangeNotifier;
 180
 181     private final MessageTracker appendEntriesReplyTracker;
 182
 183     private final ShardTransactionActorFactory transactionActorFactory;
 184
 185     private final ShardSnapshotCohort snapshotCohort;
 186
 187     private final DataTreeChangeListenerSupport treeChangeSupport = new DataTreeChangeListenerSupport(this);
 188
 189     private ShardSnapshot restoreFromSnapshot;
 190
 191     private final ShardTransactionMessageRetrySupport messageRetrySupport;
 192
 193     private final FrontendMetadata frontendMetadata;
 194     private Map<FrontendIdentifier, LeaderFrontendState> knownFrontends = ImmutableMap.of();
 195     private boolean paused;
 196
 197     private final MessageSlicer responseMessageSlicer;
 198     private final Dispatchers dispatchers;
 199
 200     private final MessageAssembler requestMessageAssembler;
 201
 202     protected Shard(final AbstractBuilder<?, ?> builder) {
 203         super(builder.getId().toString(), builder.getPeerAddresses(),
 204                 Optional.of(builder.getDatastoreContext().getShardRaftConfig()), DataStoreVersions.CURRENT_VERSION);
 205
 206         this.name = builder.getId().toString();
 207         this.shardName = builder.getId().getShardName();
 208         this.datastoreContext = builder.getDatastoreContext();
 209         this.restoreFromSnapshot = builder.getRestoreFromSnapshot();
 210         this.frontendMetadata = new FrontendMetadata(name);
 211
 212         setPersistence(datastoreContext.isPersistent());
 213
 214         LOG.info("Shard created : {}, persistent : {}", name, datastoreContext.isPersistent());
 215
 216         ShardDataTreeChangeListenerPublisherActorProxy treeChangeListenerPublisher =
 217                 new ShardDataTreeChangeListenerPublisherActorProxy(getContext(), name + "-DTCL-publisher", name);
 218         if (builder.getDataTree() != null) {
 219             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getDataTree(),
 220                     treeChangeListenerPublisher, name, frontendMetadata);
 221         } else {
 222             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getTreeType(),
 223                     builder.getDatastoreContext().getStoreRoot(), treeChangeListenerPublisher, name, frontendMetadata);
 224         }
 225
 226         shardMBean = ShardMBeanFactory.getShardStatsMBean(name, datastoreContext.getDataStoreMXBeanType(), this);
 227
 228         if (isMetricsCaptureEnabled()) {
 229             getContext().become(new MeteringBehavior(this));
 230         }
 231
 232         commitCoordinator = new ShardCommitCoordinator(store, LOG, this.name);
 233
 234         setTransactionCommitTimeout();
 235
 236         // create a notifier actor for each cluster member
 237         roleChangeNotifier = createRoleChangeNotifier(name);
 238
 239         appendEntriesReplyTracker = new MessageTracker(AppendEntriesReply.class,
 240                 getRaftActorContext().getConfigParams().getIsolatedCheckIntervalInMillis());
 241
 242         dispatchers = new Dispatchers(context().system().dispatchers());
 243         transactionActorFactory = new ShardTransactionActorFactory(store, datastoreContext,
 244             dispatchers.getDispatcherPath(Dispatchers.DispatcherType.Transaction),
 245                 self(), getContext(), shardMBean, builder.getId().getShardName());
 246
 247         snapshotCohort = ShardSnapshotCohort.create(getContext(), builder.getId().getMemberName(), store, LOG,
 248             this.name);
 249
 250         messageRetrySupport = new ShardTransactionMessageRetrySupport(this);
 251
 252         responseMessageSlicer = MessageSlicer.builder().logContext(this.name)
 253                 .messageSliceSize(datastoreContext.getMaximumMessageSliceSize())
 254                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 255                 .expireStateAfterInactivity(2, TimeUnit.MINUTES).build();
 256
 257         requestMessageAssembler = MessageAssembler.builder().logContext(this.name)
 258                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 259                 .assembledMessageCallback((message, sender) -> self().tell(message, sender))
 260                 .expireStateAfterInactivity(datastoreContext.getRequestTimeout(), TimeUnit.NANOSECONDS).build();
 261
 262         listenerInfoMXBean = new ShardDataTreeListenerInfoMXBeanImpl(name, datastoreContext.getDataStoreMXBeanType(),
 263                 self());
 264         listenerInfoMXBean.register();
 265     }
 266
 267     private void setTransactionCommitTimeout() {
 268         transactionCommitTimeout = TimeUnit.MILLISECONDS.convert(
 269                 datastoreContext.getShardTransactionCommitTimeoutInSeconds(), TimeUnit.SECONDS) / 2;
 270     }
 271
 272     private Optional<ActorRef> createRoleChangeNotifier(final String shardId) {
 273         ActorRef shardRoleChangeNotifier = this.getContext().actorOf(
 274             RoleChangeNotifier.getProps(shardId), shardId + "-notifier");
 275         return Optional.of(shardRoleChangeNotifier);
 276     }
 277
 278     @Override
 279     public void postStop() {
 280         LOG.info("Stopping Shard {}", persistenceId());
 281
 282         super.postStop();
 283
 284         messageRetrySupport.close();
 285
 286         if (txCommitTimeoutCheckSchedule != null) {
 287             txCommitTimeoutCheckSchedule.cancel();
 288         }
 289
 290         commitCoordinator.abortPendingTransactions("Transaction aborted due to shutdown.", this);
 291
 292         shardMBean.unregisterMBean();
 293         listenerInfoMXBean.unregister();
 294     }
 295
 296     @Override
 297     protected void handleRecover(final Object message) {
 298         LOG.debug("{}: onReceiveRecover: Received message {} from {}", persistenceId(), message.getClass(),
 299             getSender());
 300
 301         super.handleRecover(message);
 302         if (LOG.isTraceEnabled()) {
 303             appendEntriesReplyTracker.begin();
 304         }
 305     }
 306
 307     @Override
 308     protected void handleNonRaftCommand(final Object message) {
 309         try (MessageTracker.Context context = appendEntriesReplyTracker.received(message)) {
 310             final Optional<Error> maybeError = context.error();
 311             if (maybeError.isPresent()) {
 312                 LOG.trace("{} : AppendEntriesReply failed to arrive at the expected interval {}", persistenceId(),
 313                     maybeError.get());
 314             }
 315
 316             store.resetTransactionBatch();
 317
 318             if (message instanceof RequestEnvelope) {
 319                 handleRequestEnvelope((RequestEnvelope)message);
 320             } else if (MessageAssembler.isHandledMessage(message)) {
 321                 handleRequestAssemblerMessage(message);
 322             } else if (message instanceof ConnectClientRequest) {
 323                 handleConnectClient((ConnectClientRequest)message);
 324             } else if (CreateTransaction.isSerializedType(message)) {
 325                 handleCreateTransaction(message);
 326             } else if (message instanceof BatchedModifications) {
 327                 handleBatchedModifications((BatchedModifications)message);
 328             } else if (message instanceof ForwardedReadyTransaction) {
 329                 handleForwardedReadyTransaction((ForwardedReadyTransaction) message);
 330             } else if (message instanceof ReadyLocalTransaction) {
 331                 handleReadyLocalTransaction((ReadyLocalTransaction)message);
 332             } else if (CanCommitTransaction.isSerializedType(message)) {
 333                 handleCanCommitTransaction(CanCommitTransaction.fromSerializable(message));
 334             } else if (CommitTransaction.isSerializedType(message)) {
 335                 handleCommitTransaction(CommitTransaction.fromSerializable(message));
 336             } else if (AbortTransaction.isSerializedType(message)) {
 337                 handleAbortTransaction(AbortTransaction.fromSerializable(message));
 338             } else if (CloseTransactionChain.isSerializedType(message)) {
 339                 closeTransactionChain(CloseTransactionChain.fromSerializable(message));
 340             } else if (message instanceof RegisterDataTreeChangeListener) {
 341                 treeChangeSupport.onMessage((RegisterDataTreeChangeListener) message, isLeader(), hasLeader());
 342             } else if (message instanceof UpdateSchemaContext) {
 343                 updateSchemaContext((UpdateSchemaContext) message);
 344             } else if (message instanceof PeerAddressResolved) {
 345                 PeerAddressResolved resolved = (PeerAddressResolved) message;
 346                 setPeerAddress(resolved.getPeerId(), resolved.getPeerAddress());
 347             } else if (TX_COMMIT_TIMEOUT_CHECK_MESSAGE.equals(message)) {
 348                 commitTimeoutCheck();
 349             } else if (message instanceof DatastoreContext) {
 350                 onDatastoreContext((DatastoreContext)message);
 351             } else if (message instanceof RegisterRoleChangeListener) {
 352                 roleChangeNotifier.get().forward(message, context());
 353             } else if (message instanceof FollowerInitialSyncUpStatus) {
 354                 shardMBean.setFollowerInitialSyncStatus(((FollowerInitialSyncUpStatus) message).isInitialSyncDone());
 355                 context().parent().tell(message, self());
 356             } else if (GET_SHARD_MBEAN_MESSAGE.equals(message)) {
 357                 sender().tell(getShardMBean(), self());
 358             } else if (message instanceof GetShardDataTree) {
 359                 sender().tell(store.getDataTree(), self());
 360             } else if (message instanceof ServerRemoved) {
 361                 context().parent().forward(message, context());
 362             } else if (ShardTransactionMessageRetrySupport.TIMER_MESSAGE_CLASS.isInstance(message)) {
 363                 messageRetrySupport.onTimerMessage(message);
 364             } else if (message instanceof DataTreeCohortActorRegistry.CohortRegistryCommand) {
 365                 store.processCohortRegistryCommand(getSender(),
 366                         (DataTreeCohortActorRegistry.CohortRegistryCommand) message);
 367             } else if (message instanceof PersistAbortTransactionPayload) {
 368                 final TransactionIdentifier txId = ((PersistAbortTransactionPayload) message).getTransactionId();
 369                 persistPayload(txId, AbortTransactionPayload.create(txId,
 370                     datastoreContext.getInitialPayloadSerializedBufferCapacity()), true);
 371                 persistPayload(txId, PurgeTransactionPayload.create(txId,
 372                     datastoreContext.getInitialPayloadSerializedBufferCapacity()), false);
 373             } else if (message instanceof MakeLeaderLocal) {
 374                 onMakeLeaderLocal();
 375             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
 376                 store.resumeNextPendingTransaction();
 377             } else if (!responseMessageSlicer.handleMessage(message)) {
 378                 super.handleNonRaftCommand(message);
 379             }
 380         }
 381     }
 382
 383     private void handleRequestAssemblerMessage(final Object message) {
 384         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
 385             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
 386             requestMessageAssembler.handleMessage(message, self());
 387         });
 388     }
 389
 390     @SuppressWarnings("checkstyle:IllegalCatch")
 391     private void handleRequestEnvelope(final RequestEnvelope envelope) {
 392         final long now = ticker().read();
 393         try {
 394             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
 395             if (success != null) {
 396                 final long executionTimeNanos = ticker().read() - now;
 397                 if (success instanceof SliceableMessage) {
 398                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
 399                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
 400                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
 401                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
 402                             .onFailureCallback(t -> LOG.warn("Error slicing response {}", success, t)).build()));
 403                 } else {
 404                     envelope.sendSuccess(success, executionTimeNanos);
 405                 }
 406             }
 407         } catch (RequestException e) {
 408             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
 409             envelope.sendFailure(e, ticker().read() - now);
 410         } catch (Exception e) {
 411             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
 412             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
 413                 ticker().read() - now);
 414         }
 415     }
 416
 417     private void commitTimeoutCheck() {
 418         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
 419         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
 420         requestMessageAssembler.checkExpiredAssembledMessageState();
 421     }
 422
 423     private Optional<Long> updateAccess(final SimpleShardDataTreeCohort cohort) {
 424         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
 425         final LeaderFrontendState state = knownFrontends.get(frontend);
 426         if (state == null) {
 427             // Not tell-based protocol, do nothing
 428             return Optional.absent();
 429         }
 430
 431         if (isIsolatedLeader()) {
 432             // We are isolated and no new request can come through until we emerge from it. We are still updating
 433             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
 434             return Optional.of(state.getLastSeenTicks());
 435         }
 436
 437         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
 438         return Optional.of(state.getLastConnectTicks());
 439     }
 440
 441     private void onMakeLeaderLocal() {
 442         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
 443         if (isLeader()) {
 444             getSender().tell(new Status.Success(null), getSelf());
 445             return;
 446         }
 447
 448         final ActorSelection leader = getLeader();
 449
 450         if (leader == null) {
 451             // Leader is not present. The cluster is most likely trying to
 452             // elect a leader and we should let that run its normal course
 453
 454             // TODO we can wait for the election to complete and retry the
 455             // request. We can also let the caller retry by sending a flag
 456             // in the response indicating the request is "reTryable".
 457             getSender().tell(new Failure(
 458                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
 459                             + "Currently there is no leader for " + persistenceId())),
 460                     getSelf());
 461             return;
 462         }
 463
 464         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
 465     }
 466
 467     // Acquire our frontend tracking handle and verify generation matches
 468     @Nullable
 469     private LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
 470         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
 471         if (existing != null) {
 472             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
 473             if (cmp == 0) {
 474                 existing.touch();
 475                 return existing;
 476             }
 477             if (cmp > 0) {
 478                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
 479                 throw new RetiredGenerationException(clientId.getGeneration(),
 480                     existing.getIdentifier().getGeneration());
 481             }
 482
 483             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 484             existing.retire();
 485             knownFrontends.remove(clientId.getFrontendId());
 486         } else {
 487             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 488         }
 489
 490         return null;
 491     }
 492
 493     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 494         final LeaderFrontendState ret = findFrontend(clientId);
 495         if (ret != null) {
 496             return ret;
 497         }
 498
 499         // TODO: a dedicated exception would be better, but this is technically true, too
 500         throw new OutOfSequenceEnvelopeException(0);
 501     }
 502
 503     @Nonnull
 504     private static ABIVersion selectVersion(final ConnectClientRequest message) {
 505         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
 506         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
 507             if (clientRange.contains(v)) {
 508                 return v;
 509             }
 510         }
 511
 512         throw new IllegalArgumentException(String.format(
 513             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
 514             clientRange));
 515     }
 516
 517     @SuppressWarnings("checkstyle:IllegalCatch")
 518     private void handleConnectClient(final ConnectClientRequest message) {
 519         try {
 520             final ClientIdentifier clientId = message.getTarget();
 521             final LeaderFrontendState existing = findFrontend(clientId);
 522             if (existing != null) {
 523                 existing.touch();
 524             }
 525
 526             if (!isLeader() || !isLeaderActive()) {
 527                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 528                                 + "isLeadershipTransferInProgress: {}.",
 529                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
 530                 throw new NotLeaderException(getSelf());
 531             }
 532
 533             final ABIVersion selectedVersion = selectVersion(message);
 534             final LeaderFrontendState frontend;
 535             if (existing == null) {
 536                 frontend = new LeaderFrontendState(persistenceId(), clientId, store);
 537                 knownFrontends.put(clientId.getFrontendId(), frontend);
 538                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
 539             } else {
 540                 frontend = existing;
 541             }
 542
 543             frontend.reconnect();
 544             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
 545                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
 546                 ActorRef.noSender());
 547         } catch (RequestException | RuntimeException e) {
 548             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
 549         }
 550     }
 551
 552     @Nullable
 553     private RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 554             throws RequestException {
 555         // We are not the leader, hence we want to fail-fast.
 556         if (!isLeader() || paused || !isLeaderActive()) {
 557             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 558                             + "isLeadershipTransferInProgress: {}, paused: {}",
 559                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 560             throw new NotLeaderException(getSelf());
 561         }
 562
 563         final Request<?, ?> request = envelope.getMessage();
 564         if (request instanceof TransactionRequest) {
 565             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
 566             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
 567             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 568         } else if (request instanceof LocalHistoryRequest) {
 569             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
 570             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
 571             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 572         } else {
 573             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 574             throw new UnsupportedRequestException(request);
 575         }
 576     }
 577
 578     private boolean hasLeader() {
 579         return getLeaderId() != null;
 580     }
 581
 582     public int getPendingTxCommitQueueSize() {
 583         return store.getQueueSize();
 584     }
 585
 586     public int getCohortCacheSize() {
 587         return commitCoordinator.getCohortCacheSize();
 588     }
 589
 590     @Override
 591     protected Optional<ActorRef> getRoleChangeNotifier() {
 592         return roleChangeNotifier;
 593     }
 594
 595     String getShardName() {
 596         return shardName;
 597     }
 598
 599     @Override
 600     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 601             final short leaderPayloadVersion) {
 602         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 603                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 604     }
 605
 606     protected void onDatastoreContext(final DatastoreContext context) {
 607         datastoreContext = context;
 608
 609         setTransactionCommitTimeout();
 610
 611         setPersistence(datastoreContext.isPersistent());
 612
 613         updateConfigParams(datastoreContext.getShardRaftConfig());
 614     }
 615
 616     // applyState() will be invoked once consensus is reached on the payload
 617     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 618         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 619         if (canSkipPayload) {
 620             applyState(self(), id, payload);
 621         } else {
 622             // We are faking the sender
 623             persistData(self(), id, payload, batchHint);
 624         }
 625     }
 626
 627     private void handleCommitTransaction(final CommitTransaction commit) {
 628         if (isLeader()) {
 629             commitCoordinator.handleCommit(commit.getTransactionId(), getSender(), this);
 630         } else {
 631             ActorSelection leader = getLeader();
 632             if (leader == null) {
 633                 messageRetrySupport.addMessageToRetry(commit, getSender(),
 634                         "Could not commit transaction " + commit.getTransactionId());
 635             } else {
 636                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 637                 leader.forward(commit, getContext());
 638             }
 639         }
 640     }
 641
 642     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 643         LOG.debug("{}: Can committing transaction {}", persistenceId(), canCommit.getTransactionId());
 644
 645         if (isLeader()) {
 646             commitCoordinator.handleCanCommit(canCommit.getTransactionId(), getSender(), this);
 647         } else {
 648             ActorSelection leader = getLeader();
 649             if (leader == null) {
 650                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 651                         "Could not canCommit transaction " + canCommit.getTransactionId());
 652             } else {
 653                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 654                 leader.forward(canCommit, getContext());
 655             }
 656         }
 657     }
 658
 659     @SuppressWarnings("checkstyle:IllegalCatch")
 660     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 661         try {
 662             commitCoordinator.handleBatchedModifications(batched, sender, this);
 663         } catch (Exception e) {
 664             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 665                     batched.getTransactionId(), e);
 666             sender.tell(new Failure(e), getSelf());
 667         }
 668     }
 669
 670     private void handleBatchedModifications(final BatchedModifications batched) {
 671         // This message is sent to prepare the modifications transaction directly on the Shard as an
 672         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 673         // BatchedModifications message, the caller sets the ready flag in the message indicating
 674         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 675         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 676         // ReadyTransaction message.
 677
 678         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 679         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 680         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 681         // window where it could have a stale leader during leadership transitions.
 682         //
 683         boolean isLeaderActive = isLeaderActive();
 684         if (isLeader() && isLeaderActive) {
 685             handleBatchedModificationsLocal(batched, getSender());
 686         } else {
 687             ActorSelection leader = getLeader();
 688             if (!isLeaderActive || leader == null) {
 689                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 690                         "Could not process BatchedModifications " + batched.getTransactionId());
 691             } else {
 692                 // If this is not the first batch and leadership changed in between batched messages,
 693                 // we need to reconstruct previous BatchedModifications from the transaction
 694                 // DataTreeModification, honoring the max batched modification count, and forward all the
 695                 // previous BatchedModifications to the new leader.
 696                 Collection<BatchedModifications> newModifications = commitCoordinator
 697                         .createForwardedBatchedModifications(batched,
 698                                 datastoreContext.getShardBatchedModificationCount());
 699
 700                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 701                         newModifications.size(), leader);
 702
 703                 for (BatchedModifications bm : newModifications) {
 704                     leader.forward(bm, getContext());
 705                 }
 706             }
 707         }
 708     }
 709
 710     private boolean failIfIsolatedLeader(final ActorRef sender) {
 711         if (isIsolatedLeader()) {
 712             sender.tell(new Failure(new NoShardLeaderException(String.format(
 713                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 714                     + " other follower nodes are down or this node is isolated by a network partition.",
 715                     persistenceId()))), getSelf());
 716             return true;
 717         }
 718
 719         return false;
 720     }
 721
 722     protected boolean isIsolatedLeader() {
 723         return getRaftState() == RaftState.IsolatedLeader;
 724     }
 725
 726     @SuppressWarnings("checkstyle:IllegalCatch")
 727     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 728         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
 729
 730         boolean isLeaderActive = isLeaderActive();
 731         if (isLeader() && isLeaderActive) {
 732             try {
 733                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 734             } catch (Exception e) {
 735                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
 736                         message.getTransactionId(), e);
 737                 getSender().tell(new Failure(e), getSelf());
 738             }
 739         } else {
 740             ActorSelection leader = getLeader();
 741             if (!isLeaderActive || leader == null) {
 742                 messageRetrySupport.addMessageToRetry(message, getSender(),
 743                         "Could not process ready local transaction " + message.getTransactionId());
 744             } else {
 745                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 746                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 747                 leader.forward(message, getContext());
 748             }
 749         }
 750     }
 751
 752     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 753         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 754
 755         boolean isLeaderActive = isLeaderActive();
 756         if (isLeader() && isLeaderActive) {
 757             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 758         } else {
 759             ActorSelection leader = getLeader();
 760             if (!isLeaderActive || leader == null) {
 761                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 762                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 763             } else {
 764                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 765
 766                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 767                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 768                         forwardedReady.getParticipatingShardNames());
 769                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 770                 leader.forward(readyLocal, getContext());
 771             }
 772         }
 773     }
 774
 775     private void handleAbortTransaction(final AbortTransaction abort) {
 776         doAbortTransaction(abort.getTransactionId(), getSender());
 777     }
 778
 779     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 780         commitCoordinator.handleAbort(transactionID, sender, this);
 781     }
 782
 783     private void handleCreateTransaction(final Object message) {
 784         if (isLeader()) {
 785             createTransaction(CreateTransaction.fromSerializable(message));
 786         } else if (getLeader() != null) {
 787             getLeader().forward(message, getContext());
 788         } else {
 789             getSender().tell(new Failure(new NoShardLeaderException(
 790                     "Could not create a shard transaction", persistenceId())), getSelf());
 791         }
 792     }
 793
 794     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 795         final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 796         store.closeTransactionChain(id, null);
 797         store.purgeTransactionChain(id, null);
 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     @Nonnull
 846     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 847         if (restoreFromSnapshot == null) {
 848             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 849         }
 850
 851         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 852     }
 853
 854     @Override
 855     protected void onRecoveryComplete() {
 856         restoreFromSnapshot = null;
 857
 858         //notify shard manager
 859         getContext().parent().tell(new ActorInitialized(), getSelf());
 860
 861         // Being paranoid here - this method should only be called once but just in case...
 862         if (txCommitTimeoutCheckSchedule == null) {
 863             // Schedule a message to be periodically sent to check if the current in-progress
 864             // transaction should be expired and aborted.
 865             FiniteDuration period = Duration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 866             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 867                     period, period, getSelf(),
 868                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 869         }
 870     }
 871
 872     @Override
 873     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 874         if (data instanceof Payload) {
 875             try {
 876                 store.applyReplicatedPayload(identifier, (Payload)data);
 877             } catch (DataValidationFailedException | IOException e) {
 878                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 879             }
 880         } else {
 881             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
 882         }
 883     }
 884
 885     @Override
 886     protected void onStateChanged() {
 887         boolean isLeader = isLeader();
 888         boolean hasLeader = hasLeader();
 889         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
 890
 891         // If this actor is no longer the leader close all the transaction chains
 892         if (!isLeader) {
 893             if (LOG.isDebugEnabled()) {
 894                 LOG.debug(
 895                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
 896                     persistenceId(), getId());
 897             }
 898
 899             paused = false;
 900             store.purgeLeaderState();
 901         }
 902
 903         if (hasLeader && !isIsolatedLeader()) {
 904             messageRetrySupport.retryMessages();
 905         }
 906     }
 907
 908     @Override
 909     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
 910         shardMBean.incrementLeadershipChangeCount();
 911         paused = false;
 912
 913         if (!isLeader()) {
 914             if (!knownFrontends.isEmpty()) {
 915                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
 916                 knownFrontends = ImmutableMap.of();
 917             }
 918
 919             requestMessageAssembler.close();
 920
 921             if (!hasLeader()) {
 922                 // No leader anywhere, nothing else to do
 923                 return;
 924             }
 925
 926             // Another leader was elected. If we were the previous leader and had pending transactions, convert
 927             // them to transaction messages and send to the new leader.
 928             ActorSelection leader = getLeader();
 929             if (leader != null) {
 930                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
 931
 932                 if (!messagesToForward.isEmpty()) {
 933                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
 934                             messagesToForward.size(), leader);
 935
 936                     for (Object message : messagesToForward) {
 937                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
 938
 939                         leader.tell(message, self());
 940                     }
 941                 }
 942             } else {
 943                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
 944                         + "change and the leader address isn't available.", this);
 945             }
 946         } else {
 947             // We have become the leader, we need to reconstruct frontend state
 948             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 949             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
 950         }
 951
 952         if (!isIsolatedLeader()) {
 953             messageRetrySupport.retryMessages();
 954         }
 955     }
 956
 957     /**
 958      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
 959      *
 960      * @return the converted messages
 961      */
 962     public Collection<?> convertPendingTransactionsToMessages() {
 963         return commitCoordinator.convertPendingTransactionsToMessages(
 964                 datastoreContext.getShardBatchedModificationCount());
 965     }
 966
 967     @Override
 968     protected void pauseLeader(final Runnable operation) {
 969         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
 970         paused = true;
 971
 972         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
 973         knownFrontends.values().forEach(LeaderFrontendState::retire);
 974         knownFrontends = ImmutableMap.of();
 975
 976         store.setRunOnPendingTransactionsComplete(operation);
 977     }
 978
 979     @Override
 980     protected void unpauseLeader() {
 981         LOG.debug("{}: In unpauseLeader", persistenceId());
 982         paused = false;
 983
 984         store.setRunOnPendingTransactionsComplete(null);
 985
 986         // Restore tell-based protocol state as if we were becoming the leader
 987         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 988     }
 989
 990     @Override
 991     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
 992         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
 993                 .commitCohortActors(store.getCohortActors());
 994     }
 995
 996     @Override
 997     public String persistenceId() {
 998         return this.name;
 999     }
1000
1001     @VisibleForTesting
1002     ShardCommitCoordinator getCommitCoordinator() {
1003         return commitCoordinator;
1004     }
1005
1006     public DatastoreContext getDatastoreContext() {
1007         return datastoreContext;
1008     }
1009
1010     @VisibleForTesting
1011     public ShardDataTree getDataStore() {
1012         return store;
1013     }
1014
1015     @VisibleForTesting
1016     ShardStats getShardMBean() {
1017         return shardMBean;
1018     }
1019
1020     public static Builder builder() {
1021         return new Builder();
1022     }
1023
1024     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1025         private final Class<S> shardClass;
1026         private ShardIdentifier id;
1027         private Map<String, String> peerAddresses = Collections.emptyMap();
1028         private DatastoreContext datastoreContext;
1029         private SchemaContextProvider schemaContextProvider;
1030         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1031         private DataTree dataTree;
1032         private volatile boolean sealed;
1033
1034         protected AbstractBuilder(final Class<S> shardClass) {
1035             this.shardClass = shardClass;
1036         }
1037
1038         protected void checkSealed() {
1039             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1040         }
1041
1042         @SuppressWarnings("unchecked")
1043         private T self() {
1044             return (T) this;
1045         }
1046
1047         public T id(final ShardIdentifier newId) {
1048             checkSealed();
1049             this.id = newId;
1050             return self();
1051         }
1052
1053         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1054             checkSealed();
1055             this.peerAddresses = newPeerAddresses;
1056             return self();
1057         }
1058
1059         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1060             checkSealed();
1061             this.datastoreContext = newDatastoreContext;
1062             return self();
1063         }
1064
1065         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1066             checkSealed();
1067             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1068             return self();
1069         }
1070
1071         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1072             checkSealed();
1073             this.restoreFromSnapshot = newRestoreFromSnapshot;
1074             return self();
1075         }
1076
1077         public T dataTree(final DataTree newDataTree) {
1078             checkSealed();
1079             this.dataTree = newDataTree;
1080             return self();
1081         }
1082
1083         public ShardIdentifier getId() {
1084             return id;
1085         }
1086
1087         public Map<String, String> getPeerAddresses() {
1088             return peerAddresses;
1089         }
1090
1091         public DatastoreContext getDatastoreContext() {
1092             return datastoreContext;
1093         }
1094
1095         public SchemaContext getSchemaContext() {
1096             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1097         }
1098
1099         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1100             return restoreFromSnapshot;
1101         }
1102
1103         public DataTree getDataTree() {
1104             return dataTree;
1105         }
1106
1107         public TreeType getTreeType() {
1108             switch (datastoreContext.getLogicalStoreType()) {
1109                 case CONFIGURATION:
1110                     return TreeType.CONFIGURATION;
1111                 case OPERATIONAL:
1112                     return TreeType.OPERATIONAL;
1113                 default:
1114                     throw new IllegalStateException("Unhandled logical store type "
1115                             + datastoreContext.getLogicalStoreType());
1116             }
1117         }
1118
1119         protected void verify() {
1120             Preconditions.checkNotNull(id, "id should not be null");
1121             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1122             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1123             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1124         }
1125
1126         public Props props() {
1127             sealed = true;
1128             verify();
1129             return Props.create(shardClass, this);
1130         }
1131     }
1132
1133     public static class Builder extends AbstractBuilder<Builder, Shard> {
1134         Builder() {
1135             super(Shard.class);
1136         }
1137     }
1138
1139     Ticker ticker() {
1140         return Ticker.systemTicker();
1141     }
1142
1143     void scheduleNextPendingTransaction() {
1144         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1145     }
1146 }