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 static com.google.common.base.Verify.verify;
  11
  12 import akka.actor.ActorRef;
  13 import akka.actor.ActorSelection;
  14 import akka.actor.Cancellable;
  15 import akka.actor.ExtendedActorSystem;
  16 import akka.actor.Props;
  17 import akka.actor.Status;
  18 import akka.actor.Status.Failure;
  19 import akka.serialization.JavaSerializer;
  20 import akka.serialization.Serialization;
  21 import com.google.common.annotations.VisibleForTesting;
  22 import com.google.common.base.Optional;
  23 import com.google.common.base.Preconditions;
  24 import com.google.common.base.Ticker;
  25 import com.google.common.base.Verify;
  26 import com.google.common.collect.ImmutableList;
  27 import com.google.common.collect.ImmutableMap;
  28 import com.google.common.collect.Range;
  29 import java.io.IOException;
  30 import java.util.Arrays;
  31 import java.util.Collection;
  32 import java.util.Collections;
  33 import java.util.HashMap;
  34 import java.util.Map;
  35 import java.util.OptionalLong;
  36 import java.util.concurrent.TimeUnit;
  37 import org.eclipse.jdt.annotation.NonNull;
  38 import org.eclipse.jdt.annotation.Nullable;
  39 import org.opendaylight.controller.cluster.access.ABIVersion;
  40 import org.opendaylight.controller.cluster.access.commands.ConnectClientRequest;
  41 import org.opendaylight.controller.cluster.access.commands.ConnectClientSuccess;
  42 import org.opendaylight.controller.cluster.access.commands.LocalHistoryRequest;
  43 import org.opendaylight.controller.cluster.access.commands.NotLeaderException;
  44 import org.opendaylight.controller.cluster.access.commands.OutOfSequenceEnvelopeException;
  45 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
  46 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  47 import org.opendaylight.controller.cluster.access.concepts.FrontendIdentifier;
  48 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
  49 import org.opendaylight.controller.cluster.access.concepts.Request;
  50 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
  51 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  52 import org.opendaylight.controller.cluster.access.concepts.RequestSuccess;
  53 import org.opendaylight.controller.cluster.access.concepts.RetiredGenerationException;
  54 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
  55 import org.opendaylight.controller.cluster.access.concepts.SliceableMessage;
  56 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  57 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
  58 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
  59 import org.opendaylight.controller.cluster.common.actor.Dispatchers;
  60 import org.opendaylight.controller.cluster.common.actor.Dispatchers.DispatcherType;
  61 import org.opendaylight.controller.cluster.common.actor.MessageTracker;
  62 import org.opendaylight.controller.cluster.common.actor.MessageTracker.Error;
  63 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
  64 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  65 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  66 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardDataTreeListenerInfoMXBeanImpl;
  67 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardMBeanFactory;
  68 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
  69 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
  70 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
  71 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  72 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransaction;
  73 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  74 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
  75 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  76 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  77 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
  78 import org.opendaylight.controller.cluster.datastore.messages.GetShardDataTree;
  79 import org.opendaylight.controller.cluster.datastore.messages.MakeLeaderLocal;
  80 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
  81 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
  82 import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
  83 import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
  84 import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
  85 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
  86 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot;
  87 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot.ShardSnapshot;
  88 import org.opendaylight.controller.cluster.datastore.persisted.DisableTrackingPayload;
  89 import org.opendaylight.controller.cluster.messaging.MessageAssembler;
  90 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
  91 import org.opendaylight.controller.cluster.messaging.SliceOptions;
  92 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
  93 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
  94 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
  95 import org.opendaylight.controller.cluster.raft.LeadershipTransferFailedException;
  96 import org.opendaylight.controller.cluster.raft.RaftActor;
  97 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
  98 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
  99 import org.opendaylight.controller.cluster.raft.RaftState;
 100 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
 101 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
 102 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
 103 import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
 104 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
 105 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
 106 import org.opendaylight.yangtools.concepts.Identifier;
 107 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
 108 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
 109 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
 110 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
 111 import org.opendaylight.yangtools.yang.model.api.SchemaContextProvider;
 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 java.util.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 MakeLeaderLocal) {
 368                 onMakeLeaderLocal();
 369             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
 370                 store.resumeNextPendingTransaction();
 371             } else if (!responseMessageSlicer.handleMessage(message)) {
 372                 super.handleNonRaftCommand(message);
 373             }
 374         }
 375     }
 376
 377     private void handleRequestAssemblerMessage(final Object message) {
 378         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
 379             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
 380             requestMessageAssembler.handleMessage(message, self());
 381         });
 382     }
 383
 384     @SuppressWarnings("checkstyle:IllegalCatch")
 385     private void handleRequestEnvelope(final RequestEnvelope envelope) {
 386         final long now = ticker().read();
 387         try {
 388             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
 389             if (success != null) {
 390                 final long executionTimeNanos = ticker().read() - now;
 391                 if (success instanceof SliceableMessage) {
 392                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
 393                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
 394                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
 395                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
 396                             .onFailureCallback(t -> LOG.warn("Error slicing response {}", success, t)).build()));
 397                 } else {
 398                     envelope.sendSuccess(success, executionTimeNanos);
 399                 }
 400             }
 401         } catch (RequestException e) {
 402             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
 403             envelope.sendFailure(e, ticker().read() - now);
 404         } catch (Exception e) {
 405             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
 406             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
 407                 ticker().read() - now);
 408         }
 409     }
 410
 411     private void commitTimeoutCheck() {
 412         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
 413         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
 414         requestMessageAssembler.checkExpiredAssembledMessageState();
 415     }
 416
 417     private OptionalLong updateAccess(final SimpleShardDataTreeCohort cohort) {
 418         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
 419         final LeaderFrontendState state = knownFrontends.get(frontend);
 420         if (state == null) {
 421             // Not tell-based protocol, do nothing
 422             return OptionalLong.empty();
 423         }
 424
 425         if (isIsolatedLeader()) {
 426             // We are isolated and no new request can come through until we emerge from it. We are still updating
 427             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
 428             return OptionalLong.of(state.getLastSeenTicks());
 429         }
 430
 431         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
 432         return OptionalLong.of(state.getLastConnectTicks());
 433     }
 434
 435     private void disableTracking(final DisableTrackingPayload payload) {
 436         final ClientIdentifier clientId = payload.getIdentifier();
 437         LOG.debug("{}: disabling tracking of {}", persistenceId(), clientId);
 438         frontendMetadata.disableTracking(clientId);
 439
 440         if (isLeader()) {
 441             final FrontendIdentifier frontendId = clientId.getFrontendId();
 442             final LeaderFrontendState frontend = knownFrontends.get(frontendId);
 443             if (frontend != null) {
 444                 if (clientId.equals(frontend.getIdentifier())) {
 445                     if (!(frontend instanceof LeaderFrontendState.Disabled)) {
 446                         verify(knownFrontends.replace(frontendId, frontend,
 447                             new LeaderFrontendState.Disabled(persistenceId(), clientId, store)));
 448                         LOG.debug("{}: leader state for {} disabled", persistenceId(), clientId);
 449                     } else {
 450                         LOG.debug("{}: leader state {} is already disabled", persistenceId(), frontend);
 451                     }
 452                 } else {
 453                     LOG.debug("{}: leader state {} does not match {}", persistenceId(), frontend, clientId);
 454                 }
 455             } else {
 456                 LOG.debug("{}: leader state for {} not found", persistenceId(), clientId);
 457                 knownFrontends.put(frontendId, new LeaderFrontendState.Disabled(persistenceId(), clientId,
 458                     getDataStore()));
 459             }
 460         }
 461     }
 462
 463     private void onMakeLeaderLocal() {
 464         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
 465         if (isLeader()) {
 466             getSender().tell(new Status.Success(null), getSelf());
 467             return;
 468         }
 469
 470         final ActorSelection leader = getLeader();
 471
 472         if (leader == null) {
 473             // Leader is not present. The cluster is most likely trying to
 474             // elect a leader and we should let that run its normal course
 475
 476             // TODO we can wait for the election to complete and retry the
 477             // request. We can also let the caller retry by sending a flag
 478             // in the response indicating the request is "reTryable".
 479             getSender().tell(new Failure(
 480                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
 481                             + "Currently there is no leader for " + persistenceId())),
 482                     getSelf());
 483             return;
 484         }
 485
 486         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
 487     }
 488
 489     // Acquire our frontend tracking handle and verify generation matches
 490     private @Nullable LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
 491         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
 492         if (existing != null) {
 493             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
 494             if (cmp == 0) {
 495                 existing.touch();
 496                 return existing;
 497             }
 498             if (cmp > 0) {
 499                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
 500                 throw new RetiredGenerationException(clientId.getGeneration(),
 501                     existing.getIdentifier().getGeneration());
 502             }
 503
 504             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 505             existing.retire();
 506             knownFrontends.remove(clientId.getFrontendId());
 507         } else {
 508             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 509         }
 510
 511         return null;
 512     }
 513
 514     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 515         final LeaderFrontendState ret = findFrontend(clientId);
 516         if (ret != null) {
 517             return ret;
 518         }
 519
 520         // TODO: a dedicated exception would be better, but this is technically true, too
 521         throw new OutOfSequenceEnvelopeException(0);
 522     }
 523
 524     private static @NonNull ABIVersion selectVersion(final ConnectClientRequest message) {
 525         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
 526         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
 527             if (clientRange.contains(v)) {
 528                 return v;
 529             }
 530         }
 531
 532         throw new IllegalArgumentException(String.format(
 533             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
 534             clientRange));
 535     }
 536
 537     @SuppressWarnings("checkstyle:IllegalCatch")
 538     private void handleConnectClient(final ConnectClientRequest message) {
 539         try {
 540             final ClientIdentifier clientId = message.getTarget();
 541             final LeaderFrontendState existing = findFrontend(clientId);
 542             if (existing != null) {
 543                 existing.touch();
 544             }
 545
 546             if (!isLeader() || !isLeaderActive()) {
 547                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 548                                 + "isLeadershipTransferInProgress: {}.",
 549                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
 550                 throw new NotLeaderException(getSelf());
 551             }
 552
 553             final ABIVersion selectedVersion = selectVersion(message);
 554             final LeaderFrontendState frontend;
 555             if (existing == null) {
 556                 frontend = new LeaderFrontendState.Enabled(persistenceId(), clientId, store);
 557                 knownFrontends.put(clientId.getFrontendId(), frontend);
 558                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
 559             } else {
 560                 frontend = existing;
 561             }
 562
 563             frontend.reconnect();
 564             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
 565                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
 566                 ActorRef.noSender());
 567         } catch (RequestException | RuntimeException e) {
 568             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
 569         }
 570     }
 571
 572     private @Nullable RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 573             throws RequestException {
 574         // We are not the leader, hence we want to fail-fast.
 575         if (!isLeader() || paused || !isLeaderActive()) {
 576             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 577                             + "isLeadershipTransferInProgress: {}, paused: {}",
 578                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 579             throw new NotLeaderException(getSelf());
 580         }
 581
 582         final Request<?, ?> request = envelope.getMessage();
 583         if (request instanceof TransactionRequest) {
 584             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
 585             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
 586             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 587         } else if (request instanceof LocalHistoryRequest) {
 588             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
 589             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
 590             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 591         } else {
 592             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 593             throw new UnsupportedRequestException(request);
 594         }
 595     }
 596
 597     private boolean hasLeader() {
 598         return getLeaderId() != null;
 599     }
 600
 601     public int getPendingTxCommitQueueSize() {
 602         return store.getQueueSize();
 603     }
 604
 605     public int getCohortCacheSize() {
 606         return commitCoordinator.getCohortCacheSize();
 607     }
 608
 609     @Override
 610     protected Optional<ActorRef> getRoleChangeNotifier() {
 611         return roleChangeNotifier;
 612     }
 613
 614     String getShardName() {
 615         return shardName;
 616     }
 617
 618     @Override
 619     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 620             final short leaderPayloadVersion) {
 621         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 622                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 623     }
 624
 625     protected void onDatastoreContext(final DatastoreContext context) {
 626         datastoreContext = context;
 627
 628         setTransactionCommitTimeout();
 629
 630         setPersistence(datastoreContext.isPersistent());
 631
 632         updateConfigParams(datastoreContext.getShardRaftConfig());
 633     }
 634
 635     // applyState() will be invoked once consensus is reached on the payload
 636     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 637         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 638         if (canSkipPayload) {
 639             applyState(self(), id, payload);
 640         } else {
 641             // We are faking the sender
 642             persistData(self(), id, payload, batchHint);
 643         }
 644     }
 645
 646     private void handleCommitTransaction(final CommitTransaction commit) {
 647         final TransactionIdentifier txId = commit.getTransactionId();
 648         if (isLeader()) {
 649             askProtocolEncountered(txId);
 650             commitCoordinator.handleCommit(txId, getSender(), this);
 651         } else {
 652             ActorSelection leader = getLeader();
 653             if (leader == null) {
 654                 messageRetrySupport.addMessageToRetry(commit, getSender(), "Could not commit transaction " + txId);
 655             } else {
 656                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 657                 leader.forward(commit, getContext());
 658             }
 659         }
 660     }
 661
 662     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 663         final TransactionIdentifier txId = canCommit.getTransactionId();
 664         LOG.debug("{}: Can committing transaction {}", persistenceId(), txId);
 665
 666         if (isLeader()) {
 667             askProtocolEncountered(txId);
 668             commitCoordinator.handleCanCommit(txId, getSender(), this);
 669         } else {
 670             ActorSelection leader = getLeader();
 671             if (leader == null) {
 672                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 673                         "Could not canCommit transaction " + txId);
 674             } else {
 675                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 676                 leader.forward(canCommit, getContext());
 677             }
 678         }
 679     }
 680
 681     @SuppressWarnings("checkstyle:IllegalCatch")
 682     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 683         askProtocolEncountered(batched.getTransactionId());
 684
 685         try {
 686             commitCoordinator.handleBatchedModifications(batched, sender, this);
 687         } catch (Exception e) {
 688             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 689                     batched.getTransactionId(), e);
 690             sender.tell(new Failure(e), getSelf());
 691         }
 692     }
 693
 694     private void handleBatchedModifications(final BatchedModifications batched) {
 695         // This message is sent to prepare the modifications transaction directly on the Shard as an
 696         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 697         // BatchedModifications message, the caller sets the ready flag in the message indicating
 698         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 699         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 700         // ReadyTransaction message.
 701
 702         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 703         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 704         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 705         // window where it could have a stale leader during leadership transitions.
 706         //
 707         boolean isLeaderActive = isLeaderActive();
 708         if (isLeader() && isLeaderActive) {
 709             handleBatchedModificationsLocal(batched, getSender());
 710         } else {
 711             ActorSelection leader = getLeader();
 712             if (!isLeaderActive || leader == null) {
 713                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 714                         "Could not process BatchedModifications " + batched.getTransactionId());
 715             } else {
 716                 // If this is not the first batch and leadership changed in between batched messages,
 717                 // we need to reconstruct previous BatchedModifications from the transaction
 718                 // DataTreeModification, honoring the max batched modification count, and forward all the
 719                 // previous BatchedModifications to the new leader.
 720                 Collection<BatchedModifications> newModifications = commitCoordinator
 721                         .createForwardedBatchedModifications(batched,
 722                                 datastoreContext.getShardBatchedModificationCount());
 723
 724                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 725                         newModifications.size(), leader);
 726
 727                 for (BatchedModifications bm : newModifications) {
 728                     leader.forward(bm, getContext());
 729                 }
 730             }
 731         }
 732     }
 733
 734     private boolean failIfIsolatedLeader(final ActorRef sender) {
 735         if (isIsolatedLeader()) {
 736             sender.tell(new Failure(new NoShardLeaderException(String.format(
 737                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 738                     + " other follower nodes are down or this node is isolated by a network partition.",
 739                     persistenceId()))), getSelf());
 740             return true;
 741         }
 742
 743         return false;
 744     }
 745
 746     protected boolean isIsolatedLeader() {
 747         return getRaftState() == RaftState.IsolatedLeader;
 748     }
 749
 750     @SuppressWarnings("checkstyle:IllegalCatch")
 751     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 752         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
 753
 754         boolean isLeaderActive = isLeaderActive();
 755         if (isLeader() && isLeaderActive) {
 756             try {
 757                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 758             } catch (Exception e) {
 759                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
 760                         message.getTransactionId(), e);
 761                 getSender().tell(new Failure(e), getSelf());
 762             }
 763         } else {
 764             ActorSelection leader = getLeader();
 765             if (!isLeaderActive || leader == null) {
 766                 messageRetrySupport.addMessageToRetry(message, getSender(),
 767                         "Could not process ready local transaction " + message.getTransactionId());
 768             } else {
 769                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 770                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 771                 leader.forward(message, getContext());
 772             }
 773         }
 774     }
 775
 776     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 777         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 778
 779         boolean isLeaderActive = isLeaderActive();
 780         if (isLeader() && isLeaderActive) {
 781             askProtocolEncountered(forwardedReady.getTransactionId());
 782             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 783         } else {
 784             ActorSelection leader = getLeader();
 785             if (!isLeaderActive || leader == null) {
 786                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 787                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 788             } else {
 789                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 790
 791                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 792                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 793                         forwardedReady.getParticipatingShardNames());
 794                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 795                 leader.forward(readyLocal, getContext());
 796             }
 797         }
 798     }
 799
 800     private void handleAbortTransaction(final AbortTransaction abort) {
 801         final TransactionIdentifier transactionId = abort.getTransactionId();
 802         askProtocolEncountered(transactionId);
 803         doAbortTransaction(transactionId, getSender());
 804     }
 805
 806     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 807         commitCoordinator.handleAbort(transactionID, sender, this);
 808     }
 809
 810     private void handleCreateTransaction(final Object message) {
 811         if (isLeader()) {
 812             createTransaction(CreateTransaction.fromSerializable(message));
 813         } else if (getLeader() != null) {
 814             getLeader().forward(message, getContext());
 815         } else {
 816             getSender().tell(new Failure(new NoShardLeaderException(
 817                     "Could not create a shard transaction", persistenceId())), getSelf());
 818         }
 819     }
 820
 821     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 822         if (isLeader()) {
 823             final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 824             askProtocolEncountered(id.getClientId());
 825             store.closeTransactionChain(id);
 826         } else if (getLeader() != null) {
 827             getLeader().forward(closeTransactionChain, getContext());
 828         } else {
 829             LOG.warn("{}: Could not close transaction {}", persistenceId(), closeTransactionChain.getIdentifier());
 830         }
 831     }
 832
 833     @SuppressWarnings("checkstyle:IllegalCatch")
 834     private void createTransaction(final CreateTransaction createTransaction) {
 835         askProtocolEncountered(createTransaction.getTransactionId());
 836
 837         try {
 838             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
 839                     && failIfIsolatedLeader(getSender())) {
 840                 return;
 841             }
 842
 843             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 844                 createTransaction.getTransactionId());
 845
 846             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 847                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 848         } catch (Exception e) {
 849             getSender().tell(new Failure(e), getSelf());
 850         }
 851     }
 852
 853     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
 854         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 855         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 856             transactionId);
 857     }
 858
 859     // Called on leader only
 860     private void askProtocolEncountered(final TransactionIdentifier transactionId) {
 861         askProtocolEncountered(transactionId.getHistoryId().getClientId());
 862     }
 863
 864     // Called on leader only
 865     private void askProtocolEncountered(final ClientIdentifier clientId) {
 866         final FrontendIdentifier frontend = clientId.getFrontendId();
 867         final LeaderFrontendState state = knownFrontends.get(frontend);
 868         if (!(state instanceof LeaderFrontendState.Disabled)) {
 869             LOG.debug("{}: encountered ask-based client {}, disabling transaction tracking", persistenceId(), clientId);
 870             if (knownFrontends.isEmpty()) {
 871                 knownFrontends = new HashMap<>();
 872             }
 873             knownFrontends.put(frontend, new LeaderFrontendState.Disabled(persistenceId(), clientId, getDataStore()));
 874
 875             persistPayload(clientId, DisableTrackingPayload.create(clientId,
 876                 datastoreContext.getInitialPayloadSerializedBufferCapacity()), false);
 877         }
 878     }
 879
 880     private void updateSchemaContext(final UpdateSchemaContext message) {
 881         updateSchemaContext(message.getSchemaContext());
 882     }
 883
 884     @VisibleForTesting
 885     void updateSchemaContext(final SchemaContext schemaContext) {
 886         store.updateSchemaContext(schemaContext);
 887     }
 888
 889     private boolean isMetricsCaptureEnabled() {
 890         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 891         return config.isMetricCaptureEnabled();
 892     }
 893
 894     @Override
 895     @VisibleForTesting
 896     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 897         return snapshotCohort;
 898     }
 899
 900     @Override
 901     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 902         if (restoreFromSnapshot == null) {
 903             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 904         }
 905
 906         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 907     }
 908
 909     @Override
 910     protected void onRecoveryComplete() {
 911         restoreFromSnapshot = null;
 912
 913         //notify shard manager
 914         getContext().parent().tell(new ActorInitialized(), getSelf());
 915
 916         // Being paranoid here - this method should only be called once but just in case...
 917         if (txCommitTimeoutCheckSchedule == null) {
 918             // Schedule a message to be periodically sent to check if the current in-progress
 919             // transaction should be expired and aborted.
 920             FiniteDuration period = FiniteDuration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 921             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 922                     period, period, getSelf(),
 923                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 924         }
 925     }
 926
 927     @Override
 928     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 929         if (data instanceof Payload) {
 930             if (data instanceof DisableTrackingPayload) {
 931                 disableTracking((DisableTrackingPayload) data);
 932                 return;
 933             }
 934
 935             try {
 936                 store.applyReplicatedPayload(identifier, (Payload)data);
 937             } catch (DataValidationFailedException | IOException e) {
 938                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 939             }
 940         } else {
 941             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
 942         }
 943     }
 944
 945     @Override
 946     protected void onStateChanged() {
 947         boolean isLeader = isLeader();
 948         boolean hasLeader = hasLeader();
 949         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
 950
 951         // If this actor is no longer the leader close all the transaction chains
 952         if (!isLeader) {
 953             if (LOG.isDebugEnabled()) {
 954                 LOG.debug(
 955                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
 956                     persistenceId(), getId());
 957             }
 958
 959             paused = false;
 960             store.purgeLeaderState();
 961         }
 962
 963         if (hasLeader && !isIsolatedLeader()) {
 964             messageRetrySupport.retryMessages();
 965         }
 966     }
 967
 968     @Override
 969     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
 970         shardMBean.incrementLeadershipChangeCount();
 971         paused = false;
 972
 973         if (!isLeader()) {
 974             if (!knownFrontends.isEmpty()) {
 975                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
 976                 knownFrontends = ImmutableMap.of();
 977             }
 978
 979             requestMessageAssembler.close();
 980
 981             if (!hasLeader()) {
 982                 // No leader anywhere, nothing else to do
 983                 return;
 984             }
 985
 986             // Another leader was elected. If we were the previous leader and had pending transactions, convert
 987             // them to transaction messages and send to the new leader.
 988             ActorSelection leader = getLeader();
 989             if (leader != null) {
 990                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
 991
 992                 if (!messagesToForward.isEmpty()) {
 993                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
 994                             messagesToForward.size(), leader);
 995
 996                     for (Object message : messagesToForward) {
 997                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
 998
 999                         leader.tell(message, self());
1000                     }
1001                 }
1002             } else {
1003                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
1004                         + "change and the leader address isn't available.", this);
1005             }
1006         } else {
1007             // We have become the leader, we need to reconstruct frontend state
1008             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
1009             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
1010         }
1011
1012         if (!isIsolatedLeader()) {
1013             messageRetrySupport.retryMessages();
1014         }
1015     }
1016
1017     /**
1018      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
1019      *
1020      * @return the converted messages
1021      */
1022     public Collection<?> convertPendingTransactionsToMessages() {
1023         return commitCoordinator.convertPendingTransactionsToMessages(
1024                 datastoreContext.getShardBatchedModificationCount());
1025     }
1026
1027     @Override
1028     protected void pauseLeader(final Runnable operation) {
1029         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
1030         paused = true;
1031
1032         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
1033         if (datastoreContext.isUseTellBasedProtocol()) {
1034             knownFrontends.values().forEach(LeaderFrontendState::retire);
1035             knownFrontends = ImmutableMap.of();
1036         }
1037
1038         store.setRunOnPendingTransactionsComplete(operation);
1039     }
1040
1041     @Override
1042     protected void unpauseLeader() {
1043         LOG.debug("{}: In unpauseLeader", persistenceId());
1044         paused = false;
1045
1046         store.setRunOnPendingTransactionsComplete(null);
1047
1048         // Restore tell-based protocol state as if we were becoming the leader
1049         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
1050     }
1051
1052     @Override
1053     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
1054         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
1055                 .commitCohortActors(store.getCohortActors());
1056     }
1057
1058     @Override
1059     public String persistenceId() {
1060         return this.name;
1061     }
1062
1063     @VisibleForTesting
1064     ShardCommitCoordinator getCommitCoordinator() {
1065         return commitCoordinator;
1066     }
1067
1068     public DatastoreContext getDatastoreContext() {
1069         return datastoreContext;
1070     }
1071
1072     @VisibleForTesting
1073     public ShardDataTree getDataStore() {
1074         return store;
1075     }
1076
1077     @VisibleForTesting
1078     ShardStats getShardMBean() {
1079         return shardMBean;
1080     }
1081
1082     public static Builder builder() {
1083         return new Builder();
1084     }
1085
1086     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1087         private final Class<S> shardClass;
1088         private ShardIdentifier id;
1089         private Map<String, String> peerAddresses = Collections.emptyMap();
1090         private DatastoreContext datastoreContext;
1091         private SchemaContextProvider schemaContextProvider;
1092         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1093         private DataTree dataTree;
1094         private volatile boolean sealed;
1095
1096         protected AbstractBuilder(final Class<S> shardClass) {
1097             this.shardClass = shardClass;
1098         }
1099
1100         protected void checkSealed() {
1101             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1102         }
1103
1104         @SuppressWarnings("unchecked")
1105         private T self() {
1106             return (T) this;
1107         }
1108
1109         public T id(final ShardIdentifier newId) {
1110             checkSealed();
1111             this.id = newId;
1112             return self();
1113         }
1114
1115         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1116             checkSealed();
1117             this.peerAddresses = newPeerAddresses;
1118             return self();
1119         }
1120
1121         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1122             checkSealed();
1123             this.datastoreContext = newDatastoreContext;
1124             return self();
1125         }
1126
1127         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1128             checkSealed();
1129             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1130             return self();
1131         }
1132
1133         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1134             checkSealed();
1135             this.restoreFromSnapshot = newRestoreFromSnapshot;
1136             return self();
1137         }
1138
1139         public T dataTree(final DataTree newDataTree) {
1140             checkSealed();
1141             this.dataTree = newDataTree;
1142             return self();
1143         }
1144
1145         public ShardIdentifier getId() {
1146             return id;
1147         }
1148
1149         public Map<String, String> getPeerAddresses() {
1150             return peerAddresses;
1151         }
1152
1153         public DatastoreContext getDatastoreContext() {
1154             return datastoreContext;
1155         }
1156
1157         public SchemaContext getSchemaContext() {
1158             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1159         }
1160
1161         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1162             return restoreFromSnapshot;
1163         }
1164
1165         public DataTree getDataTree() {
1166             return dataTree;
1167         }
1168
1169         public TreeType getTreeType() {
1170             switch (datastoreContext.getLogicalStoreType()) {
1171                 case CONFIGURATION:
1172                     return TreeType.CONFIGURATION;
1173                 case OPERATIONAL:
1174                     return TreeType.OPERATIONAL;
1175                 default:
1176                     throw new IllegalStateException("Unhandled logical store type "
1177                             + datastoreContext.getLogicalStoreType());
1178             }
1179         }
1180
1181         protected void verify() {
1182             Preconditions.checkNotNull(id, "id should not be null");
1183             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1184             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1185             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1186         }
1187
1188         public Props props() {
1189             sealed = true;
1190             verify();
1191             return Props.create(shardClass, this);
1192         }
1193     }
1194
1195     public static class Builder extends AbstractBuilder<Builder, Shard> {
1196         Builder() {
1197             super(Shard.class);
1198         }
1199     }
1200
1201     Ticker ticker() {
1202         return Ticker.systemTicker();
1203     }
1204
1205     void scheduleNextPendingTransaction() {
1206         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1207     }
1208 }