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             } else if (message instanceof MakeLeaderLocal) {
 369                 onMakeLeaderLocal();
 370             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
 371                 store.resumeNextPendingTransaction();
 372             } else if (!responseMessageSlicer.handleMessage(message)) {
 373                 super.handleNonRaftCommand(message);
 374             }
 375         }
 376     }
 377
 378     private void handleRequestAssemblerMessage(final Object message) {
 379         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
 380             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
 381             requestMessageAssembler.handleMessage(message, self());
 382         });
 383     }
 384
 385     @SuppressWarnings("checkstyle:IllegalCatch")
 386     private void handleRequestEnvelope(final RequestEnvelope envelope) {
 387         final long now = ticker().read();
 388         try {
 389             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
 390             if (success != null) {
 391                 final long executionTimeNanos = ticker().read() - now;
 392                 if (success instanceof SliceableMessage) {
 393                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
 394                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
 395                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
 396                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
 397                             .onFailureCallback(t -> LOG.warn("Error slicing response {}", success, t)).build()));
 398                 } else {
 399                     envelope.sendSuccess(success, executionTimeNanos);
 400                 }
 401             }
 402         } catch (RequestException e) {
 403             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
 404             envelope.sendFailure(e, ticker().read() - now);
 405         } catch (Exception e) {
 406             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
 407             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
 408                 ticker().read() - now);
 409         }
 410     }
 411
 412     private void commitTimeoutCheck() {
 413         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
 414         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
 415         requestMessageAssembler.checkExpiredAssembledMessageState();
 416     }
 417
 418     private Optional<Long> updateAccess(final SimpleShardDataTreeCohort cohort) {
 419         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
 420         final LeaderFrontendState state = knownFrontends.get(frontend);
 421         if (state == null) {
 422             // Not tell-based protocol, do nothing
 423             return Optional.absent();
 424         }
 425
 426         if (isIsolatedLeader()) {
 427             // We are isolated and no new request can come through until we emerge from it. We are still updating
 428             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
 429             return Optional.of(state.getLastSeenTicks());
 430         }
 431
 432         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
 433         return Optional.of(state.getLastConnectTicks());
 434     }
 435
 436     private void onMakeLeaderLocal() {
 437         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
 438         if (isLeader()) {
 439             getSender().tell(new Status.Success(null), getSelf());
 440             return;
 441         }
 442
 443         final ActorSelection leader = getLeader();
 444
 445         if (leader == null) {
 446             // Leader is not present. The cluster is most likely trying to
 447             // elect a leader and we should let that run its normal course
 448
 449             // TODO we can wait for the election to complete and retry the
 450             // request. We can also let the caller retry by sending a flag
 451             // in the response indicating the request is "reTryable".
 452             getSender().tell(new Failure(
 453                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
 454                             + "Currently there is no leader for " + persistenceId())),
 455                     getSelf());
 456             return;
 457         }
 458
 459         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
 460     }
 461
 462     // Acquire our frontend tracking handle and verify generation matches
 463     private @Nullable LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
 464         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
 465         if (existing != null) {
 466             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
 467             if (cmp == 0) {
 468                 existing.touch();
 469                 return existing;
 470             }
 471             if (cmp > 0) {
 472                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
 473                 throw new RetiredGenerationException(clientId.getGeneration(),
 474                     existing.getIdentifier().getGeneration());
 475             }
 476
 477             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 478             existing.retire();
 479             knownFrontends.remove(clientId.getFrontendId());
 480         } else {
 481             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 482         }
 483
 484         return null;
 485     }
 486
 487     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 488         final LeaderFrontendState ret = findFrontend(clientId);
 489         if (ret != null) {
 490             return ret;
 491         }
 492
 493         // TODO: a dedicated exception would be better, but this is technically true, too
 494         throw new OutOfSequenceEnvelopeException(0);
 495     }
 496
 497     private static @NonNull ABIVersion selectVersion(final ConnectClientRequest message) {
 498         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
 499         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
 500             if (clientRange.contains(v)) {
 501                 return v;
 502             }
 503         }
 504
 505         throw new IllegalArgumentException(String.format(
 506             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
 507             clientRange));
 508     }
 509
 510     @SuppressWarnings("checkstyle:IllegalCatch")
 511     private void handleConnectClient(final ConnectClientRequest message) {
 512         try {
 513             final ClientIdentifier clientId = message.getTarget();
 514             final LeaderFrontendState existing = findFrontend(clientId);
 515             if (existing != null) {
 516                 existing.touch();
 517             }
 518
 519             if (!isLeader() || !isLeaderActive()) {
 520                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 521                                 + "isLeadershipTransferInProgress: {}.",
 522                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
 523                 throw new NotLeaderException(getSelf());
 524             }
 525
 526             final ABIVersion selectedVersion = selectVersion(message);
 527             final LeaderFrontendState frontend;
 528             if (existing == null) {
 529                 frontend = new LeaderFrontendState(persistenceId(), clientId, store);
 530                 knownFrontends.put(clientId.getFrontendId(), frontend);
 531                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
 532             } else {
 533                 frontend = existing;
 534             }
 535
 536             frontend.reconnect();
 537             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
 538                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
 539                 ActorRef.noSender());
 540         } catch (RequestException | RuntimeException e) {
 541             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
 542         }
 543     }
 544
 545     private @Nullable RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 546             throws RequestException {
 547         // We are not the leader, hence we want to fail-fast.
 548         if (!isLeader() || paused || !isLeaderActive()) {
 549             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 550                             + "isLeadershipTransferInProgress: {}, paused: {}",
 551                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 552             throw new NotLeaderException(getSelf());
 553         }
 554
 555         final Request<?, ?> request = envelope.getMessage();
 556         if (request instanceof TransactionRequest) {
 557             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
 558             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
 559             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 560         } else if (request instanceof LocalHistoryRequest) {
 561             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
 562             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
 563             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 564         } else {
 565             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 566             throw new UnsupportedRequestException(request);
 567         }
 568     }
 569
 570     private boolean hasLeader() {
 571         return getLeaderId() != null;
 572     }
 573
 574     public int getPendingTxCommitQueueSize() {
 575         return store.getQueueSize();
 576     }
 577
 578     public int getCohortCacheSize() {
 579         return commitCoordinator.getCohortCacheSize();
 580     }
 581
 582     @Override
 583     protected Optional<ActorRef> getRoleChangeNotifier() {
 584         return roleChangeNotifier;
 585     }
 586
 587     String getShardName() {
 588         return shardName;
 589     }
 590
 591     @Override
 592     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 593             final short leaderPayloadVersion) {
 594         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 595                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 596     }
 597
 598     protected void onDatastoreContext(final DatastoreContext context) {
 599         datastoreContext = context;
 600
 601         setTransactionCommitTimeout();
 602
 603         setPersistence(datastoreContext.isPersistent());
 604
 605         updateConfigParams(datastoreContext.getShardRaftConfig());
 606     }
 607
 608     // applyState() will be invoked once consensus is reached on the payload
 609     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 610         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 611         if (canSkipPayload) {
 612             applyState(self(), id, payload);
 613         } else {
 614             // We are faking the sender
 615             persistData(self(), id, payload, batchHint);
 616         }
 617     }
 618
 619     private void handleCommitTransaction(final CommitTransaction commit) {
 620         if (isLeader()) {
 621             commitCoordinator.handleCommit(commit.getTransactionId(), getSender(), this);
 622         } else {
 623             ActorSelection leader = getLeader();
 624             if (leader == null) {
 625                 messageRetrySupport.addMessageToRetry(commit, getSender(),
 626                         "Could not commit transaction " + commit.getTransactionId());
 627             } else {
 628                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 629                 leader.forward(commit, getContext());
 630             }
 631         }
 632     }
 633
 634     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 635         LOG.debug("{}: Can committing transaction {}", persistenceId(), canCommit.getTransactionId());
 636
 637         if (isLeader()) {
 638             commitCoordinator.handleCanCommit(canCommit.getTransactionId(), getSender(), this);
 639         } else {
 640             ActorSelection leader = getLeader();
 641             if (leader == null) {
 642                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 643                         "Could not canCommit transaction " + canCommit.getTransactionId());
 644             } else {
 645                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 646                 leader.forward(canCommit, getContext());
 647             }
 648         }
 649     }
 650
 651     @SuppressWarnings("checkstyle:IllegalCatch")
 652     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 653         try {
 654             commitCoordinator.handleBatchedModifications(batched, sender, this);
 655         } catch (Exception e) {
 656             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 657                     batched.getTransactionId(), e);
 658             sender.tell(new Failure(e), getSelf());
 659         }
 660     }
 661
 662     private void handleBatchedModifications(final BatchedModifications batched) {
 663         // This message is sent to prepare the modifications transaction directly on the Shard as an
 664         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 665         // BatchedModifications message, the caller sets the ready flag in the message indicating
 666         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 667         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 668         // ReadyTransaction message.
 669
 670         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 671         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 672         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 673         // window where it could have a stale leader during leadership transitions.
 674         //
 675         boolean isLeaderActive = isLeaderActive();
 676         if (isLeader() && isLeaderActive) {
 677             handleBatchedModificationsLocal(batched, getSender());
 678         } else {
 679             ActorSelection leader = getLeader();
 680             if (!isLeaderActive || leader == null) {
 681                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 682                         "Could not process BatchedModifications " + batched.getTransactionId());
 683             } else {
 684                 // If this is not the first batch and leadership changed in between batched messages,
 685                 // we need to reconstruct previous BatchedModifications from the transaction
 686                 // DataTreeModification, honoring the max batched modification count, and forward all the
 687                 // previous BatchedModifications to the new leader.
 688                 Collection<BatchedModifications> newModifications = commitCoordinator
 689                         .createForwardedBatchedModifications(batched,
 690                                 datastoreContext.getShardBatchedModificationCount());
 691
 692                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 693                         newModifications.size(), leader);
 694
 695                 for (BatchedModifications bm : newModifications) {
 696                     leader.forward(bm, getContext());
 697                 }
 698             }
 699         }
 700     }
 701
 702     private boolean failIfIsolatedLeader(final ActorRef sender) {
 703         if (isIsolatedLeader()) {
 704             sender.tell(new Failure(new NoShardLeaderException(String.format(
 705                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 706                     + " other follower nodes are down or this node is isolated by a network partition.",
 707                     persistenceId()))), getSelf());
 708             return true;
 709         }
 710
 711         return false;
 712     }
 713
 714     protected boolean isIsolatedLeader() {
 715         return getRaftState() == RaftState.IsolatedLeader;
 716     }
 717
 718     @SuppressWarnings("checkstyle:IllegalCatch")
 719     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 720         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
 721
 722         boolean isLeaderActive = isLeaderActive();
 723         if (isLeader() && isLeaderActive) {
 724             try {
 725                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 726             } catch (Exception e) {
 727                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
 728                         message.getTransactionId(), e);
 729                 getSender().tell(new Failure(e), getSelf());
 730             }
 731         } else {
 732             ActorSelection leader = getLeader();
 733             if (!isLeaderActive || leader == null) {
 734                 messageRetrySupport.addMessageToRetry(message, getSender(),
 735                         "Could not process ready local transaction " + message.getTransactionId());
 736             } else {
 737                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 738                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 739                 leader.forward(message, getContext());
 740             }
 741         }
 742     }
 743
 744     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 745         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 746
 747         boolean isLeaderActive = isLeaderActive();
 748         if (isLeader() && isLeaderActive) {
 749             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 750         } else {
 751             ActorSelection leader = getLeader();
 752             if (!isLeaderActive || leader == null) {
 753                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 754                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 755             } else {
 756                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 757
 758                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 759                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 760                         forwardedReady.getParticipatingShardNames());
 761                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 762                 leader.forward(readyLocal, getContext());
 763             }
 764         }
 765     }
 766
 767     private void handleAbortTransaction(final AbortTransaction abort) {
 768         doAbortTransaction(abort.getTransactionId(), getSender());
 769     }
 770
 771     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 772         commitCoordinator.handleAbort(transactionID, sender, this);
 773     }
 774
 775     private void handleCreateTransaction(final Object message) {
 776         if (isLeader()) {
 777             createTransaction(CreateTransaction.fromSerializable(message));
 778         } else if (getLeader() != null) {
 779             getLeader().forward(message, getContext());
 780         } else {
 781             getSender().tell(new Failure(new NoShardLeaderException(
 782                     "Could not create a shard transaction", persistenceId())), getSelf());
 783         }
 784     }
 785
 786     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 787         if (isLeader()) {
 788             final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 789             // FIXME: CONTROLLER-1628: stage purge once no transactions are present
 790             store.closeTransactionChain(id, null);
 791             store.purgeTransactionChain(id, null);
 792         } else if (getLeader() != null) {
 793             getLeader().forward(closeTransactionChain, getContext());
 794         } else {
 795             LOG.warn("{}: Could not close transaction {}", persistenceId(), closeTransactionChain.getIdentifier());
 796         }
 797     }
 798
 799     @SuppressWarnings("checkstyle:IllegalCatch")
 800     private void createTransaction(final CreateTransaction createTransaction) {
 801         try {
 802             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
 803                     && failIfIsolatedLeader(getSender())) {
 804                 return;
 805             }
 806
 807             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 808                 createTransaction.getTransactionId());
 809
 810             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 811                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 812         } catch (Exception e) {
 813             getSender().tell(new Failure(e), getSelf());
 814         }
 815     }
 816
 817     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
 818         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 819         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 820             transactionId);
 821     }
 822
 823     private void updateSchemaContext(final UpdateSchemaContext message) {
 824         updateSchemaContext(message.getSchemaContext());
 825     }
 826
 827     @VisibleForTesting
 828     void updateSchemaContext(final SchemaContext schemaContext) {
 829         store.updateSchemaContext(schemaContext);
 830     }
 831
 832     private boolean isMetricsCaptureEnabled() {
 833         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 834         return config.isMetricCaptureEnabled();
 835     }
 836
 837     @Override
 838     @VisibleForTesting
 839     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 840         return snapshotCohort;
 841     }
 842
 843     @Override
 844     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 845         if (restoreFromSnapshot == null) {
 846             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 847         }
 848
 849         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 850     }
 851
 852     @Override
 853     protected void onRecoveryComplete() {
 854         restoreFromSnapshot = null;
 855
 856         //notify shard manager
 857         getContext().parent().tell(new ActorInitialized(), getSelf());
 858
 859         // Being paranoid here - this method should only be called once but just in case...
 860         if (txCommitTimeoutCheckSchedule == null) {
 861             // Schedule a message to be periodically sent to check if the current in-progress
 862             // transaction should be expired and aborted.
 863             FiniteDuration period = FiniteDuration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 864             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 865                     period, period, getSelf(),
 866                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 867         }
 868     }
 869
 870     @Override
 871     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 872         if (data instanceof Payload) {
 873             try {
 874                 store.applyReplicatedPayload(identifier, (Payload)data);
 875             } catch (DataValidationFailedException | IOException e) {
 876                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 877             }
 878         } else {
 879             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
 880         }
 881     }
 882
 883     @Override
 884     protected void onStateChanged() {
 885         boolean isLeader = isLeader();
 886         boolean hasLeader = hasLeader();
 887         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
 888
 889         // If this actor is no longer the leader close all the transaction chains
 890         if (!isLeader) {
 891             if (LOG.isDebugEnabled()) {
 892                 LOG.debug(
 893                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
 894                     persistenceId(), getId());
 895             }
 896
 897             paused = false;
 898             store.purgeLeaderState();
 899         }
 900
 901         if (hasLeader && !isIsolatedLeader()) {
 902             messageRetrySupport.retryMessages();
 903         }
 904     }
 905
 906     @Override
 907     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
 908         shardMBean.incrementLeadershipChangeCount();
 909         paused = false;
 910
 911         if (!isLeader()) {
 912             if (!knownFrontends.isEmpty()) {
 913                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
 914                 knownFrontends = ImmutableMap.of();
 915             }
 916
 917             requestMessageAssembler.close();
 918
 919             if (!hasLeader()) {
 920                 // No leader anywhere, nothing else to do
 921                 return;
 922             }
 923
 924             // Another leader was elected. If we were the previous leader and had pending transactions, convert
 925             // them to transaction messages and send to the new leader.
 926             ActorSelection leader = getLeader();
 927             if (leader != null) {
 928                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
 929
 930                 if (!messagesToForward.isEmpty()) {
 931                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
 932                             messagesToForward.size(), leader);
 933
 934                     for (Object message : messagesToForward) {
 935                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
 936
 937                         leader.tell(message, self());
 938                     }
 939                 }
 940             } else {
 941                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
 942                         + "change and the leader address isn't available.", this);
 943             }
 944         } else {
 945             // We have become the leader, we need to reconstruct frontend state
 946             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 947             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
 948         }
 949
 950         if (!isIsolatedLeader()) {
 951             messageRetrySupport.retryMessages();
 952         }
 953     }
 954
 955     /**
 956      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
 957      *
 958      * @return the converted messages
 959      */
 960     public Collection<?> convertPendingTransactionsToMessages() {
 961         return commitCoordinator.convertPendingTransactionsToMessages(
 962                 datastoreContext.getShardBatchedModificationCount());
 963     }
 964
 965     @Override
 966     protected void pauseLeader(final Runnable operation) {
 967         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
 968         paused = true;
 969
 970         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
 971         knownFrontends.values().forEach(LeaderFrontendState::retire);
 972         knownFrontends = ImmutableMap.of();
 973
 974         store.setRunOnPendingTransactionsComplete(operation);
 975     }
 976
 977     @Override
 978     protected void unpauseLeader() {
 979         LOG.debug("{}: In unpauseLeader", persistenceId());
 980         paused = false;
 981
 982         store.setRunOnPendingTransactionsComplete(null);
 983
 984         // Restore tell-based protocol state as if we were becoming the leader
 985         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
 986     }
 987
 988     @Override
 989     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
 990         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
 991                 .commitCohortActors(store.getCohortActors());
 992     }
 993
 994     @Override
 995     public String persistenceId() {
 996         return this.name;
 997     }
 998
 999     @VisibleForTesting
1000     ShardCommitCoordinator getCommitCoordinator() {
1001         return commitCoordinator;
1002     }
1003
1004     public DatastoreContext getDatastoreContext() {
1005         return datastoreContext;
1006     }
1007
1008     @VisibleForTesting
1009     public ShardDataTree getDataStore() {
1010         return store;
1011     }
1012
1013     @VisibleForTesting
1014     ShardStats getShardMBean() {
1015         return shardMBean;
1016     }
1017
1018     public static Builder builder() {
1019         return new Builder();
1020     }
1021
1022     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1023         private final Class<S> shardClass;
1024         private ShardIdentifier id;
1025         private Map<String, String> peerAddresses = Collections.emptyMap();
1026         private DatastoreContext datastoreContext;
1027         private SchemaContextProvider schemaContextProvider;
1028         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1029         private DataTree dataTree;
1030         private volatile boolean sealed;
1031
1032         protected AbstractBuilder(final Class<S> shardClass) {
1033             this.shardClass = shardClass;
1034         }
1035
1036         protected void checkSealed() {
1037             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1038         }
1039
1040         @SuppressWarnings("unchecked")
1041         private T self() {
1042             return (T) this;
1043         }
1044
1045         public T id(final ShardIdentifier newId) {
1046             checkSealed();
1047             this.id = newId;
1048             return self();
1049         }
1050
1051         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1052             checkSealed();
1053             this.peerAddresses = newPeerAddresses;
1054             return self();
1055         }
1056
1057         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1058             checkSealed();
1059             this.datastoreContext = newDatastoreContext;
1060             return self();
1061         }
1062
1063         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1064             checkSealed();
1065             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1066             return self();
1067         }
1068
1069         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1070             checkSealed();
1071             this.restoreFromSnapshot = newRestoreFromSnapshot;
1072             return self();
1073         }
1074
1075         public T dataTree(final DataTree newDataTree) {
1076             checkSealed();
1077             this.dataTree = newDataTree;
1078             return self();
1079         }
1080
1081         public ShardIdentifier getId() {
1082             return id;
1083         }
1084
1085         public Map<String, String> getPeerAddresses() {
1086             return peerAddresses;
1087         }
1088
1089         public DatastoreContext getDatastoreContext() {
1090             return datastoreContext;
1091         }
1092
1093         public SchemaContext getSchemaContext() {
1094             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1095         }
1096
1097         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1098             return restoreFromSnapshot;
1099         }
1100
1101         public DataTree getDataTree() {
1102             return dataTree;
1103         }
1104
1105         public TreeType getTreeType() {
1106             switch (datastoreContext.getLogicalStoreType()) {
1107                 case CONFIGURATION:
1108                     return TreeType.CONFIGURATION;
1109                 case OPERATIONAL:
1110                     return TreeType.OPERATIONAL;
1111                 default:
1112                     throw new IllegalStateException("Unhandled logical store type "
1113                             + datastoreContext.getLogicalStoreType());
1114             }
1115         }
1116
1117         protected void verify() {
1118             Preconditions.checkNotNull(id, "id should not be null");
1119             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1120             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1121             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1122         }
1123
1124         public Props props() {
1125             sealed = true;
1126             verify();
1127             return Props.create(shardClass, this);
1128         }
1129     }
1130
1131     public static class Builder extends AbstractBuilder<Builder, Shard> {
1132         Builder() {
1133             super(Shard.class);
1134         }
1135     }
1136
1137     Ticker ticker() {
1138         return Ticker.systemTicker();
1139     }
1140
1141     void scheduleNextPendingTransaction() {
1142         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1143     }
1144 }