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.Preconditions.checkState;
  11 import static com.google.common.base.Verify.verify;
  12 import static com.google.common.base.Verify.verifyNotNull;
  13 import static java.util.Objects.requireNonNull;
  14
  15 import akka.actor.ActorRef;
  16 import akka.actor.ActorSelection;
  17 import akka.actor.Cancellable;
  18 import akka.actor.ExtendedActorSystem;
  19 import akka.actor.PoisonPill;
  20 import akka.actor.Props;
  21 import akka.actor.Status;
  22 import akka.actor.Status.Failure;
  23 import akka.persistence.RecoveryCompleted;
  24 import akka.persistence.SnapshotOffer;
  25 import akka.serialization.JavaSerializer;
  26 import akka.serialization.Serialization;
  27 import com.google.common.annotations.VisibleForTesting;
  28 import com.google.common.base.Ticker;
  29 import com.google.common.collect.ImmutableList;
  30 import com.google.common.collect.ImmutableMap;
  31 import com.google.common.collect.ImmutableSet;
  32 import com.google.common.collect.Range;
  33 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  34 import java.io.IOException;
  35 import java.util.Arrays;
  36 import java.util.Collection;
  37 import java.util.Collections;
  38 import java.util.HashMap;
  39 import java.util.Map;
  40 import java.util.Optional;
  41 import java.util.OptionalLong;
  42 import java.util.concurrent.TimeUnit;
  43 import org.eclipse.jdt.annotation.NonNull;
  44 import org.eclipse.jdt.annotation.Nullable;
  45 import org.opendaylight.controller.cluster.access.ABIVersion;
  46 import org.opendaylight.controller.cluster.access.commands.ConnectClientRequest;
  47 import org.opendaylight.controller.cluster.access.commands.ConnectClientSuccess;
  48 import org.opendaylight.controller.cluster.access.commands.LocalHistoryRequest;
  49 import org.opendaylight.controller.cluster.access.commands.NotLeaderException;
  50 import org.opendaylight.controller.cluster.access.commands.OutOfSequenceEnvelopeException;
  51 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
  52 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  53 import org.opendaylight.controller.cluster.access.concepts.FrontendIdentifier;
  54 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
  55 import org.opendaylight.controller.cluster.access.concepts.Request;
  56 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
  57 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  58 import org.opendaylight.controller.cluster.access.concepts.RequestSuccess;
  59 import org.opendaylight.controller.cluster.access.concepts.RetiredGenerationException;
  60 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
  61 import org.opendaylight.controller.cluster.access.concepts.SliceableMessage;
  62 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  63 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
  64 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
  65 import org.opendaylight.controller.cluster.common.actor.Dispatchers;
  66 import org.opendaylight.controller.cluster.common.actor.Dispatchers.DispatcherType;
  67 import org.opendaylight.controller.cluster.common.actor.MessageTracker;
  68 import org.opendaylight.controller.cluster.common.actor.MessageTracker.Error;
  69 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
  70 import org.opendaylight.controller.cluster.datastore.actors.JsonExportActor;
  71 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  72 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  73 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
  74 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
  75 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  76 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransaction;
  77 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  78 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
  79 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  80 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  81 import org.opendaylight.controller.cluster.datastore.messages.DataTreeChangedReply;
  82 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
  83 import org.opendaylight.controller.cluster.datastore.messages.GetKnownClients;
  84 import org.opendaylight.controller.cluster.datastore.messages.GetKnownClientsReply;
  85 import org.opendaylight.controller.cluster.datastore.messages.GetShardDataTree;
  86 import org.opendaylight.controller.cluster.datastore.messages.MakeLeaderLocal;
  87 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
  88 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
  89 import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
  90 import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
  91 import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
  92 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
  93 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot;
  94 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot.ShardSnapshot;
  95 import org.opendaylight.controller.cluster.datastore.persisted.DisableTrackingPayload;
  96 import org.opendaylight.controller.cluster.messaging.MessageAssembler;
  97 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
  98 import org.opendaylight.controller.cluster.messaging.SliceOptions;
  99 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
 100 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
 101 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
 102 import org.opendaylight.controller.cluster.raft.LeadershipTransferFailedException;
 103 import org.opendaylight.controller.cluster.raft.RaftActor;
 104 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
 105 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
 106 import org.opendaylight.controller.cluster.raft.RaftState;
 107 import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry;
 108 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
 109 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
 110 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
 111 import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
 112 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
 113 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
 114 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.controller.config.distributed.datastore.provider.rev140612.DataStoreProperties.ExportOnRecovery;
 115 import org.opendaylight.yangtools.concepts.Identifier;
 116 import org.opendaylight.yangtools.yang.data.tree.api.DataTree;
 117 import org.opendaylight.yangtools.yang.data.tree.api.DataValidationFailedException;
 118 import org.opendaylight.yangtools.yang.data.tree.api.TreeType;
 119 import org.opendaylight.yangtools.yang.model.api.EffectiveModelContext;
 120 import org.opendaylight.yangtools.yang.model.api.EffectiveModelContextProvider;
 121 import scala.concurrent.duration.FiniteDuration;
 122
 123 /**
 124  * A Shard represents a portion of the logical data tree.
 125  *
 126  * <p>
 127  * Our Shard uses InMemoryDataTree as it's internal representation and delegates all requests it
 128  */
 129 // FIXME: non-final for testing?
 130 public class Shard extends RaftActor {
 131
 132     @VisibleForTesting
 133     static final Object TX_COMMIT_TIMEOUT_CHECK_MESSAGE = new Object() {
 134         @Override
 135         public String toString() {
 136             return "txCommitTimeoutCheck";
 137         }
 138     };
 139
 140     @VisibleForTesting
 141     static final Object GET_SHARD_MBEAN_MESSAGE = new Object() {
 142         @Override
 143         public String toString() {
 144             return "getShardMBeanMessage";
 145         }
 146     };
 147
 148     static final Object RESUME_NEXT_PENDING_TRANSACTION = new Object() {
 149         @Override
 150         public String toString() {
 151             return "resumeNextPendingTransaction";
 152         }
 153     };
 154
 155     // FIXME: shard names should be encapsulated in their own class and this should be exposed as a constant.
 156     public static final String DEFAULT_NAME = "default";
 157
 158     private static final Collection<ABIVersion> SUPPORTED_ABIVERSIONS;
 159
 160     // Make sure to keep this in sync with the journal configuration in factory-akka.conf
 161     public static final String NON_PERSISTENT_JOURNAL_ID = "akka.persistence.non-persistent.journal";
 162
 163     static {
 164         final ABIVersion[] values = ABIVersion.values();
 165         final ABIVersion[] real = Arrays.copyOfRange(values, 1, values.length - 1);
 166         SUPPORTED_ABIVERSIONS = ImmutableList.copyOf(real).reverse();
 167     }
 168
 169     // FIXME: make this a dynamic property based on mailbox size and maximum number of clients
 170     private static final int CLIENT_MAX_MESSAGES = 1000;
 171
 172     // The state of this Shard
 173     private final ShardDataTree store;
 174
 175     /// The name of this shard
 176     private final String name;
 177
 178     private final String shardName;
 179
 180     private final ShardStats shardMBean;
 181
 182     private final ShardDataTreeListenerInfoMXBeanImpl listenerInfoMXBean;
 183
 184     private DatastoreContext datastoreContext;
 185
 186     private final ShardCommitCoordinator commitCoordinator;
 187
 188     private long transactionCommitTimeout;
 189
 190     private Cancellable txCommitTimeoutCheckSchedule;
 191
 192     private final Optional<ActorRef> roleChangeNotifier;
 193
 194     private final MessageTracker appendEntriesReplyTracker;
 195
 196     private final ShardTransactionActorFactory transactionActorFactory;
 197
 198     private final ShardSnapshotCohort snapshotCohort;
 199
 200     private final DataTreeChangeListenerSupport treeChangeSupport = new DataTreeChangeListenerSupport(this);
 201
 202     private ShardSnapshot restoreFromSnapshot;
 203
 204     private final ShardTransactionMessageRetrySupport messageRetrySupport;
 205
 206     @VisibleForTesting
 207     final FrontendMetadata frontendMetadata;
 208
 209     private Map<FrontendIdentifier, LeaderFrontendState> knownFrontends = ImmutableMap.of();
 210     private boolean paused;
 211
 212     private final MessageSlicer responseMessageSlicer;
 213     private final Dispatchers dispatchers;
 214
 215     private final MessageAssembler requestMessageAssembler;
 216
 217     private final ExportOnRecovery exportOnRecovery;
 218
 219     private final ActorRef exportActor;
 220
 221     @SuppressFBWarnings(value = "MC_OVERRIDABLE_METHOD_CALL_IN_CONSTRUCTOR", justification = "Akka class design")
 222     Shard(final AbstractBuilder<?, ?> builder) {
 223         super(builder.getId().toString(), builder.getPeerAddresses(),
 224                 Optional.of(builder.getDatastoreContext().getShardRaftConfig()), DataStoreVersions.CURRENT_VERSION);
 225
 226         name = builder.getId().toString();
 227         shardName = builder.getId().getShardName();
 228         datastoreContext = builder.getDatastoreContext();
 229         restoreFromSnapshot = builder.getRestoreFromSnapshot();
 230         frontendMetadata = new FrontendMetadata(name);
 231         exportOnRecovery = datastoreContext.getExportOnRecovery();
 232
 233         switch (exportOnRecovery) {
 234             case Json:
 235                 exportActor = getContext().actorOf(JsonExportActor.props(builder.getSchemaContext(),
 236                         datastoreContext.getRecoveryExportBaseDir()));
 237                 break;
 238             case Off:
 239             default:
 240                 exportActor = null;
 241                 break;
 242         }
 243
 244         setPersistence(datastoreContext.isPersistent());
 245
 246         LOG.info("Shard created : {}, persistent : {}", name, datastoreContext.isPersistent());
 247
 248         ShardDataTreeChangeListenerPublisherActorProxy treeChangeListenerPublisher =
 249                 new ShardDataTreeChangeListenerPublisherActorProxy(getContext(), name + "-DTCL-publisher", name);
 250         if (builder.getDataTree() != null) {
 251             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getDataTree(),
 252                     treeChangeListenerPublisher, name,
 253                     frontendMetadata);
 254         } else {
 255             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getTreeType(),
 256                     builder.getDatastoreContext().getStoreRoot(), treeChangeListenerPublisher, name,
 257                     frontendMetadata);
 258         }
 259
 260         shardMBean = ShardStats.create(name, datastoreContext.getDataStoreMXBeanType(), this);
 261
 262         if (isMetricsCaptureEnabled()) {
 263             getContext().become(new MeteringBehavior(this));
 264         }
 265
 266         commitCoordinator = new ShardCommitCoordinator(store, LOG, name);
 267
 268         setTransactionCommitTimeout();
 269
 270         // create a notifier actor for each cluster member
 271         roleChangeNotifier = createRoleChangeNotifier(name);
 272
 273         appendEntriesReplyTracker = new MessageTracker(AppendEntriesReply.class,
 274                 getRaftActorContext().getConfigParams().getIsolatedCheckIntervalInMillis());
 275
 276         dispatchers = new Dispatchers(context().system().dispatchers());
 277         transactionActorFactory = new ShardTransactionActorFactory(store, datastoreContext,
 278             dispatchers.getDispatcherPath(Dispatchers.DispatcherType.Transaction),
 279                 self(), getContext(), shardMBean, builder.getId().getShardName());
 280
 281         snapshotCohort = ShardSnapshotCohort.create(getContext(), builder.getId().getMemberName(), store, LOG,
 282             name, datastoreContext);
 283
 284         messageRetrySupport = new ShardTransactionMessageRetrySupport(this);
 285
 286         responseMessageSlicer = MessageSlicer.builder().logContext(name)
 287                 .messageSliceSize(datastoreContext.getMaximumMessageSliceSize())
 288                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 289                 .expireStateAfterInactivity(2, TimeUnit.MINUTES).build();
 290
 291         requestMessageAssembler = MessageAssembler.builder().logContext(name)
 292                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 293                 .assembledMessageCallback((message, sender) -> self().tell(message, sender))
 294                 .expireStateAfterInactivity(datastoreContext.getRequestTimeout(), TimeUnit.NANOSECONDS).build();
 295
 296         listenerInfoMXBean = new ShardDataTreeListenerInfoMXBeanImpl(name, datastoreContext.getDataStoreMXBeanType(),
 297                 self());
 298         listenerInfoMXBean.register();
 299     }
 300
 301     private void setTransactionCommitTimeout() {
 302         transactionCommitTimeout = TimeUnit.MILLISECONDS.convert(
 303                 datastoreContext.getShardTransactionCommitTimeoutInSeconds(), TimeUnit.SECONDS) / 2;
 304     }
 305
 306     private Optional<ActorRef> createRoleChangeNotifier(final String shardId) {
 307         ActorRef shardRoleChangeNotifier = this.getContext().actorOf(
 308             RoleChangeNotifier.getProps(shardId), shardId + "-notifier");
 309         return Optional.of(shardRoleChangeNotifier);
 310     }
 311
 312     @Override
 313     public final void postStop() throws Exception {
 314         LOG.info("Stopping Shard {}", persistenceId());
 315
 316         super.postStop();
 317
 318         messageRetrySupport.close();
 319
 320         if (txCommitTimeoutCheckSchedule != null) {
 321             txCommitTimeoutCheckSchedule.cancel();
 322         }
 323
 324         commitCoordinator.abortPendingTransactions("Transaction aborted due to shutdown.", this);
 325
 326         shardMBean.unregisterMBean();
 327         listenerInfoMXBean.unregister();
 328     }
 329
 330     @Override
 331     protected final void handleRecover(final Object message) {
 332         LOG.debug("{}: onReceiveRecover: Received message {} from {}", persistenceId(), message.getClass(),
 333             getSender());
 334
 335         super.handleRecover(message);
 336
 337         switch (exportOnRecovery) {
 338             case Json:
 339                 if (message instanceof SnapshotOffer) {
 340                     exportActor.tell(new JsonExportActor.ExportSnapshot(store.readCurrentData().get(), name),
 341                             ActorRef.noSender());
 342                 } else if (message instanceof ReplicatedLogEntry) {
 343                     exportActor.tell(new JsonExportActor.ExportJournal((ReplicatedLogEntry) message),
 344                             ActorRef.noSender());
 345                 } else if (message instanceof RecoveryCompleted) {
 346                     exportActor.tell(new JsonExportActor.FinishExport(name), ActorRef.noSender());
 347                     exportActor.tell(PoisonPill.getInstance(), ActorRef.noSender());
 348                 }
 349                 break;
 350             case Off:
 351             default:
 352                 break;
 353         }
 354
 355         if (LOG.isTraceEnabled()) {
 356             appendEntriesReplyTracker.begin();
 357         }
 358     }
 359
 360     @Override
 361     // non-final for TestShard
 362     protected void handleNonRaftCommand(final Object message) {
 363         try (MessageTracker.Context context = appendEntriesReplyTracker.received(message)) {
 364             final Optional<Error> maybeError = context.error();
 365             if (maybeError.isPresent()) {
 366                 LOG.trace("{} : AppendEntriesReply failed to arrive at the expected interval {}", persistenceId(),
 367                     maybeError.get());
 368             }
 369
 370             store.resetTransactionBatch();
 371
 372             if (message instanceof RequestEnvelope) {
 373                 handleRequestEnvelope((RequestEnvelope)message);
 374             } else if (MessageAssembler.isHandledMessage(message)) {
 375                 handleRequestAssemblerMessage(message);
 376             } else if (message instanceof ConnectClientRequest) {
 377                 handleConnectClient((ConnectClientRequest)message);
 378             } else if (CreateTransaction.isSerializedType(message)) {
 379                 handleCreateTransaction(message);
 380             } else if (message instanceof BatchedModifications) {
 381                 handleBatchedModifications((BatchedModifications)message);
 382             } else if (message instanceof ForwardedReadyTransaction) {
 383                 handleForwardedReadyTransaction((ForwardedReadyTransaction) message);
 384             } else if (message instanceof ReadyLocalTransaction) {
 385                 handleReadyLocalTransaction((ReadyLocalTransaction)message);
 386             } else if (CanCommitTransaction.isSerializedType(message)) {
 387                 handleCanCommitTransaction(CanCommitTransaction.fromSerializable(message));
 388             } else if (CommitTransaction.isSerializedType(message)) {
 389                 handleCommitTransaction(CommitTransaction.fromSerializable(message));
 390             } else if (AbortTransaction.isSerializedType(message)) {
 391                 handleAbortTransaction(AbortTransaction.fromSerializable(message));
 392             } else if (CloseTransactionChain.isSerializedType(message)) {
 393                 closeTransactionChain(CloseTransactionChain.fromSerializable(message));
 394             } else if (message instanceof DataTreeChangedReply) {
 395                 // Ignore reply
 396             } else if (message instanceof RegisterDataTreeChangeListener) {
 397                 treeChangeSupport.onMessage((RegisterDataTreeChangeListener) message, isLeader(), hasLeader());
 398             } else if (message instanceof UpdateSchemaContext) {
 399                 updateSchemaContext((UpdateSchemaContext) message);
 400             } else if (message instanceof PeerAddressResolved) {
 401                 PeerAddressResolved resolved = (PeerAddressResolved) message;
 402                 setPeerAddress(resolved.getPeerId(), resolved.getPeerAddress());
 403             } else if (TX_COMMIT_TIMEOUT_CHECK_MESSAGE.equals(message)) {
 404                 commitTimeoutCheck();
 405             } else if (message instanceof DatastoreContext) {
 406                 onDatastoreContext((DatastoreContext)message);
 407             } else if (message instanceof RegisterRoleChangeListener) {
 408                 roleChangeNotifier.get().forward(message, context());
 409             } else if (message instanceof FollowerInitialSyncUpStatus) {
 410                 shardMBean.setFollowerInitialSyncStatus(((FollowerInitialSyncUpStatus) message).isInitialSyncDone());
 411                 context().parent().tell(message, self());
 412             } else if (GET_SHARD_MBEAN_MESSAGE.equals(message)) {
 413                 sender().tell(getShardMBean(), self());
 414             } else if (message instanceof GetShardDataTree) {
 415                 sender().tell(store.getDataTree(), self());
 416             } else if (message instanceof ServerRemoved) {
 417                 context().parent().forward(message, context());
 418             } else if (ShardTransactionMessageRetrySupport.TIMER_MESSAGE_CLASS.isInstance(message)) {
 419                 messageRetrySupport.onTimerMessage(message);
 420             } else if (message instanceof DataTreeCohortActorRegistry.CohortRegistryCommand) {
 421                 store.processCohortRegistryCommand(getSender(),
 422                         (DataTreeCohortActorRegistry.CohortRegistryCommand) message);
 423             } else if (message instanceof MakeLeaderLocal) {
 424                 onMakeLeaderLocal();
 425             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
 426                 store.resumeNextPendingTransaction();
 427             } else if (GetKnownClients.INSTANCE.equals(message)) {
 428                 handleGetKnownClients();
 429             } else if (!responseMessageSlicer.handleMessage(message)) {
 430                 super.handleNonRaftCommand(message);
 431             }
 432         }
 433     }
 434
 435     private void handleRequestAssemblerMessage(final Object message) {
 436         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
 437             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
 438             requestMessageAssembler.handleMessage(message, self());
 439         });
 440     }
 441
 442     @SuppressWarnings("checkstyle:IllegalCatch")
 443     private void handleRequestEnvelope(final RequestEnvelope envelope) {
 444         final long now = ticker().read();
 445         try {
 446             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
 447             if (success != null) {
 448                 final long executionTimeNanos = ticker().read() - now;
 449                 if (success instanceof SliceableMessage) {
 450                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
 451                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
 452                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
 453                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
 454                             .onFailureCallback(t -> LOG.warn("Error slicing response {}", success, t)).build()));
 455                 } else {
 456                     envelope.sendSuccess(success, executionTimeNanos);
 457                 }
 458             }
 459         } catch (RequestException e) {
 460             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
 461             envelope.sendFailure(e, ticker().read() - now);
 462         } catch (Exception e) {
 463             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
 464             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
 465                 ticker().read() - now);
 466         }
 467     }
 468
 469     private void commitTimeoutCheck() {
 470         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
 471         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
 472         requestMessageAssembler.checkExpiredAssembledMessageState();
 473     }
 474
 475     private OptionalLong updateAccess(final SimpleShardDataTreeCohort cohort) {
 476         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
 477         final LeaderFrontendState state = knownFrontends.get(frontend);
 478         if (state == null) {
 479             // Not tell-based protocol, do nothing
 480             return OptionalLong.empty();
 481         }
 482
 483         if (isIsolatedLeader()) {
 484             // We are isolated and no new request can come through until we emerge from it. We are still updating
 485             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
 486             return OptionalLong.of(state.getLastSeenTicks());
 487         }
 488
 489         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
 490         return OptionalLong.of(state.getLastConnectTicks());
 491     }
 492
 493     private void disableTracking(final DisableTrackingPayload payload) {
 494         final ClientIdentifier clientId = payload.getIdentifier();
 495         LOG.debug("{}: disabling tracking of {}", persistenceId(), clientId);
 496         frontendMetadata.disableTracking(clientId);
 497
 498         if (isLeader()) {
 499             final FrontendIdentifier frontendId = clientId.getFrontendId();
 500             final LeaderFrontendState frontend = knownFrontends.get(frontendId);
 501             if (frontend != null) {
 502                 if (clientId.equals(frontend.getIdentifier())) {
 503                     if (!(frontend instanceof LeaderFrontendState.Disabled)) {
 504                         verify(knownFrontends.replace(frontendId, frontend,
 505                             new LeaderFrontendState.Disabled(persistenceId(), clientId, store)));
 506                         LOG.debug("{}: leader state for {} disabled", persistenceId(), clientId);
 507                     } else {
 508                         LOG.debug("{}: leader state {} is already disabled", persistenceId(), frontend);
 509                     }
 510                 } else {
 511                     LOG.debug("{}: leader state {} does not match {}", persistenceId(), frontend, clientId);
 512                 }
 513             } else {
 514                 LOG.debug("{}: leader state for {} not found", persistenceId(), clientId);
 515                 knownFrontends.put(frontendId, new LeaderFrontendState.Disabled(persistenceId(), clientId,
 516                     getDataStore()));
 517             }
 518         }
 519     }
 520
 521     private void onMakeLeaderLocal() {
 522         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
 523         if (isLeader()) {
 524             getSender().tell(new Status.Success(null), getSelf());
 525             return;
 526         }
 527
 528         final ActorSelection leader = getLeader();
 529
 530         if (leader == null) {
 531             // Leader is not present. The cluster is most likely trying to
 532             // elect a leader and we should let that run its normal course
 533
 534             // TODO we can wait for the election to complete and retry the
 535             // request. We can also let the caller retry by sending a flag
 536             // in the response indicating the request is "reTryable".
 537             getSender().tell(new Failure(
 538                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
 539                             + "Currently there is no leader for " + persistenceId())),
 540                     getSelf());
 541             return;
 542         }
 543
 544         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
 545     }
 546
 547     // Acquire our frontend tracking handle and verify generation matches
 548     private @Nullable LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
 549         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
 550         if (existing != null) {
 551             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
 552             if (cmp == 0) {
 553                 existing.touch();
 554                 return existing;
 555             }
 556             if (cmp > 0) {
 557                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
 558                 throw new RetiredGenerationException(clientId.getGeneration(),
 559                     existing.getIdentifier().getGeneration());
 560             }
 561
 562             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 563             existing.retire();
 564             knownFrontends.remove(clientId.getFrontendId());
 565         } else {
 566             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 567         }
 568
 569         return null;
 570     }
 571
 572     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 573         final LeaderFrontendState ret = findFrontend(clientId);
 574         if (ret != null) {
 575             return ret;
 576         }
 577
 578         // TODO: a dedicated exception would be better, but this is technically true, too
 579         throw new OutOfSequenceEnvelopeException(0);
 580     }
 581
 582     private static @NonNull ABIVersion selectVersion(final ConnectClientRequest message) {
 583         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
 584         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
 585             if (clientRange.contains(v)) {
 586                 return v;
 587             }
 588         }
 589
 590         throw new IllegalArgumentException(String.format(
 591             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
 592             clientRange));
 593     }
 594
 595     @SuppressWarnings("checkstyle:IllegalCatch")
 596     private void handleConnectClient(final ConnectClientRequest message) {
 597         try {
 598             final ClientIdentifier clientId = message.getTarget();
 599             final LeaderFrontendState existing = findFrontend(clientId);
 600             if (existing != null) {
 601                 existing.touch();
 602             }
 603
 604             if (!isLeader() || !isLeaderActive()) {
 605                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 606                                 + "isLeadershipTransferInProgress: {}.",
 607                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
 608                 throw new NotLeaderException(getSelf());
 609             }
 610
 611             final ABIVersion selectedVersion = selectVersion(message);
 612             final LeaderFrontendState frontend;
 613             if (existing == null) {
 614                 frontend = new LeaderFrontendState.Enabled(persistenceId(), clientId, store);
 615                 knownFrontends.put(clientId.getFrontendId(), frontend);
 616                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
 617             } else {
 618                 frontend = existing;
 619             }
 620
 621             frontend.reconnect();
 622             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
 623                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
 624                 ActorRef.noSender());
 625         } catch (RequestException | RuntimeException e) {
 626             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
 627         }
 628     }
 629
 630     private @Nullable RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 631             throws RequestException {
 632         // We are not the leader, hence we want to fail-fast.
 633         if (!isLeader() || paused || !isLeaderActive()) {
 634             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 635                             + "isLeadershipTransferInProgress: {}, paused: {}",
 636                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 637             throw new NotLeaderException(getSelf());
 638         }
 639
 640         final Request<?, ?> request = envelope.getMessage();
 641         if (request instanceof TransactionRequest) {
 642             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
 643             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
 644             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 645         } else if (request instanceof LocalHistoryRequest) {
 646             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
 647             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
 648             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 649         } else {
 650             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 651             throw new UnsupportedRequestException(request);
 652         }
 653     }
 654
 655     private void handleGetKnownClients() {
 656         final ImmutableSet<ClientIdentifier> clients;
 657         if (isLeader()) {
 658             clients = knownFrontends.values().stream()
 659                     .map(LeaderFrontendState::getIdentifier)
 660                     .collect(ImmutableSet.toImmutableSet());
 661         } else {
 662             clients = frontendMetadata.getClients();
 663         }
 664         sender().tell(new GetKnownClientsReply(clients), self());
 665     }
 666
 667     private boolean hasLeader() {
 668         return getLeaderId() != null;
 669     }
 670
 671     final int getPendingTxCommitQueueSize() {
 672         return store.getQueueSize();
 673     }
 674
 675     final int getCohortCacheSize() {
 676         return commitCoordinator.getCohortCacheSize();
 677     }
 678
 679     @Override
 680     protected final Optional<ActorRef> getRoleChangeNotifier() {
 681         return roleChangeNotifier;
 682     }
 683
 684     final String getShardName() {
 685         return shardName;
 686     }
 687
 688     @Override
 689     protected final LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 690             final short leaderPayloadVersion) {
 691         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 692                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 693     }
 694
 695     private void onDatastoreContext(final DatastoreContext context) {
 696         datastoreContext = verifyNotNull(context);
 697
 698         setTransactionCommitTimeout();
 699
 700         setPersistence(datastoreContext.isPersistent());
 701
 702         updateConfigParams(datastoreContext.getShardRaftConfig());
 703     }
 704
 705     // applyState() will be invoked once consensus is reached on the payload
 706     // non-final for mocking
 707     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 708         final boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 709         if (canSkipPayload) {
 710             applyState(self(), id, payload);
 711         } else {
 712             // We are faking the sender
 713             persistData(self(), id, payload, batchHint);
 714         }
 715     }
 716
 717     private void handleCommitTransaction(final CommitTransaction commit) {
 718         final TransactionIdentifier txId = commit.getTransactionId();
 719         if (isLeader()) {
 720             askProtocolEncountered(txId);
 721             commitCoordinator.handleCommit(txId, getSender(), this);
 722         } else {
 723             ActorSelection leader = getLeader();
 724             if (leader == null) {
 725                 messageRetrySupport.addMessageToRetry(commit, getSender(), "Could not commit transaction " + txId);
 726             } else {
 727                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 728                 leader.forward(commit, getContext());
 729             }
 730         }
 731     }
 732
 733     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 734         final TransactionIdentifier txId = canCommit.getTransactionId();
 735         LOG.debug("{}: Can committing transaction {}", persistenceId(), txId);
 736
 737         if (isLeader()) {
 738             askProtocolEncountered(txId);
 739             commitCoordinator.handleCanCommit(txId, getSender(), this);
 740         } else {
 741             ActorSelection leader = getLeader();
 742             if (leader == null) {
 743                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 744                         "Could not canCommit transaction " + txId);
 745             } else {
 746                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 747                 leader.forward(canCommit, getContext());
 748             }
 749         }
 750     }
 751
 752     @SuppressWarnings("checkstyle:IllegalCatch")
 753     private void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 754         askProtocolEncountered(batched.getTransactionId());
 755
 756         try {
 757             commitCoordinator.handleBatchedModifications(batched, sender, this);
 758         } catch (Exception e) {
 759             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 760                     batched.getTransactionId(), e);
 761             sender.tell(new Failure(e), getSelf());
 762         }
 763     }
 764
 765     private void handleBatchedModifications(final BatchedModifications batched) {
 766         // This message is sent to prepare the modifications transaction directly on the Shard as an
 767         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 768         // BatchedModifications message, the caller sets the ready flag in the message indicating
 769         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 770         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 771         // ReadyTransaction message.
 772
 773         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 774         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 775         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 776         // window where it could have a stale leader during leadership transitions.
 777         //
 778         boolean isLeaderActive = isLeaderActive();
 779         if (isLeader() && isLeaderActive) {
 780             handleBatchedModificationsLocal(batched, getSender());
 781         } else {
 782             ActorSelection leader = getLeader();
 783             if (!isLeaderActive || leader == null) {
 784                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 785                         "Could not process BatchedModifications " + batched.getTransactionId());
 786             } else {
 787                 // If this is not the first batch and leadership changed in between batched messages,
 788                 // we need to reconstruct previous BatchedModifications from the transaction
 789                 // DataTreeModification, honoring the max batched modification count, and forward all the
 790                 // previous BatchedModifications to the new leader.
 791                 Collection<BatchedModifications> newModifications = commitCoordinator
 792                         .createForwardedBatchedModifications(batched,
 793                                 datastoreContext.getShardBatchedModificationCount());
 794
 795                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 796                         newModifications.size(), leader);
 797
 798                 for (BatchedModifications bm : newModifications) {
 799                     leader.forward(bm, getContext());
 800                 }
 801             }
 802         }
 803     }
 804
 805     private boolean failIfIsolatedLeader(final ActorRef sender) {
 806         if (isIsolatedLeader()) {
 807             sender.tell(new Failure(new NoShardLeaderException(String.format(
 808                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 809                     + " other follower nodes are down or this node is isolated by a network partition.",
 810                     persistenceId()))), getSelf());
 811             return true;
 812         }
 813
 814         return false;
 815     }
 816
 817     protected boolean isIsolatedLeader() {
 818         return getRaftState() == RaftState.IsolatedLeader;
 819     }
 820
 821     @SuppressWarnings("checkstyle:IllegalCatch")
 822     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 823         final TransactionIdentifier txId = message.getTransactionId();
 824         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), txId);
 825
 826         boolean isLeaderActive = isLeaderActive();
 827         if (isLeader() && isLeaderActive) {
 828             askProtocolEncountered(txId);
 829             try {
 830                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 831             } catch (Exception e) {
 832                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(), txId, e);
 833                 getSender().tell(new Failure(e), getSelf());
 834             }
 835         } else {
 836             ActorSelection leader = getLeader();
 837             if (!isLeaderActive || leader == null) {
 838                 messageRetrySupport.addMessageToRetry(message, getSender(),
 839                         "Could not process ready local transaction " + txId);
 840             } else {
 841                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 842                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 843                 leader.forward(message, getContext());
 844             }
 845         }
 846     }
 847
 848     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 849         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 850
 851         boolean isLeaderActive = isLeaderActive();
 852         if (isLeader() && isLeaderActive) {
 853             askProtocolEncountered(forwardedReady.getTransactionId());
 854             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 855         } else {
 856             ActorSelection leader = getLeader();
 857             if (!isLeaderActive || leader == null) {
 858                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 859                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 860             } else {
 861                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 862
 863                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 864                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 865                         forwardedReady.getParticipatingShardNames());
 866                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 867                 leader.forward(readyLocal, getContext());
 868             }
 869         }
 870     }
 871
 872     private void handleAbortTransaction(final AbortTransaction abort) {
 873         final TransactionIdentifier transactionId = abort.getTransactionId();
 874         askProtocolEncountered(transactionId);
 875         doAbortTransaction(transactionId, getSender());
 876     }
 877
 878     final void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 879         commitCoordinator.handleAbort(transactionID, sender, this);
 880     }
 881
 882     private void handleCreateTransaction(final Object message) {
 883         if (isLeader()) {
 884             createTransaction(CreateTransaction.fromSerializable(message));
 885         } else if (getLeader() != null) {
 886             getLeader().forward(message, getContext());
 887         } else {
 888             getSender().tell(new Failure(new NoShardLeaderException(
 889                     "Could not create a shard transaction", persistenceId())), getSelf());
 890         }
 891     }
 892
 893     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 894         if (isLeader()) {
 895             final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 896             askProtocolEncountered(id.getClientId());
 897             store.closeTransactionChain(id);
 898         } else if (getLeader() != null) {
 899             getLeader().forward(closeTransactionChain, getContext());
 900         } else {
 901             LOG.warn("{}: Could not close transaction {}", persistenceId(), closeTransactionChain.getIdentifier());
 902         }
 903     }
 904
 905     @SuppressWarnings("checkstyle:IllegalCatch")
 906     private void createTransaction(final CreateTransaction createTransaction) {
 907         askProtocolEncountered(createTransaction.getTransactionId());
 908
 909         try {
 910             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
 911                     && failIfIsolatedLeader(getSender())) {
 912                 return;
 913             }
 914
 915             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 916                 createTransaction.getTransactionId());
 917
 918             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 919                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 920         } catch (Exception e) {
 921             getSender().tell(new Failure(e), getSelf());
 922         }
 923     }
 924
 925     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
 926         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 927         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 928             transactionId);
 929     }
 930
 931     // Called on leader only
 932     private void askProtocolEncountered(final TransactionIdentifier transactionId) {
 933         askProtocolEncountered(transactionId.getHistoryId().getClientId());
 934     }
 935
 936     // Called on leader only
 937     private void askProtocolEncountered(final ClientIdentifier clientId) {
 938         final FrontendIdentifier frontend = clientId.getFrontendId();
 939         final LeaderFrontendState state = knownFrontends.get(frontend);
 940         if (!(state instanceof LeaderFrontendState.Disabled)) {
 941             LOG.debug("{}: encountered ask-based client {}, disabling transaction tracking", persistenceId(), clientId);
 942             if (knownFrontends.isEmpty()) {
 943                 knownFrontends = new HashMap<>();
 944             }
 945             knownFrontends.put(frontend, new LeaderFrontendState.Disabled(persistenceId(), clientId, getDataStore()));
 946
 947             persistPayload(clientId, DisableTrackingPayload.create(clientId,
 948                 datastoreContext.getInitialPayloadSerializedBufferCapacity()), false);
 949         }
 950     }
 951
 952     private void updateSchemaContext(final UpdateSchemaContext message) {
 953         updateSchemaContext(message.getEffectiveModelContext());
 954     }
 955
 956     @VisibleForTesting
 957     void updateSchemaContext(final @NonNull EffectiveModelContext schemaContext) {
 958         store.updateSchemaContext(schemaContext);
 959     }
 960
 961     private boolean isMetricsCaptureEnabled() {
 962         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 963         return config.isMetricCaptureEnabled();
 964     }
 965
 966     @Override
 967     protected final RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 968         return snapshotCohort;
 969     }
 970
 971     @Override
 972     protected final RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 973         if (restoreFromSnapshot == null) {
 974             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 975         }
 976
 977         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 978     }
 979
 980     @Override
 981     // non-final for testing
 982     protected void onRecoveryComplete() {
 983         restoreFromSnapshot = null;
 984
 985         //notify shard manager
 986         getContext().parent().tell(new ActorInitialized(), getSelf());
 987
 988         // Being paranoid here - this method should only be called once but just in case...
 989         if (txCommitTimeoutCheckSchedule == null) {
 990             // Schedule a message to be periodically sent to check if the current in-progress
 991             // transaction should be expired and aborted.
 992             FiniteDuration period = FiniteDuration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 993             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 994                     period, period, getSelf(),
 995                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 996         }
 997     }
 998
 999     @Override
1000     protected final void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
1001         if (data instanceof Payload) {
1002             if (data instanceof DisableTrackingPayload) {
1003                 disableTracking((DisableTrackingPayload) data);
1004                 return;
1005             }
1006
1007             try {
1008                 store.applyReplicatedPayload(identifier, (Payload)data);
1009             } catch (DataValidationFailedException | IOException e) {
1010                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
1011             }
1012         } else {
1013             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
1014         }
1015     }
1016
1017     @Override
1018     protected final void onStateChanged() {
1019         boolean isLeader = isLeader();
1020         boolean hasLeader = hasLeader();
1021         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
1022
1023         // If this actor is no longer the leader close all the transaction chains
1024         if (!isLeader) {
1025             if (LOG.isDebugEnabled()) {
1026                 LOG.debug(
1027                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
1028                     persistenceId(), getId());
1029             }
1030
1031             paused = false;
1032             store.purgeLeaderState();
1033         }
1034
1035         if (hasLeader && !isIsolatedLeader()) {
1036             messageRetrySupport.retryMessages();
1037         }
1038     }
1039
1040     @Override
1041     protected final void onLeaderChanged(final String oldLeader, final String newLeader) {
1042         shardMBean.incrementLeadershipChangeCount();
1043         paused = false;
1044
1045         if (!isLeader()) {
1046             if (!knownFrontends.isEmpty()) {
1047                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
1048                 knownFrontends = ImmutableMap.of();
1049             }
1050
1051             requestMessageAssembler.close();
1052
1053             if (!hasLeader()) {
1054                 // No leader anywhere, nothing else to do
1055                 return;
1056             }
1057
1058             // Another leader was elected. If we were the previous leader and had pending transactions, convert
1059             // them to transaction messages and send to the new leader.
1060             ActorSelection leader = getLeader();
1061             if (leader != null) {
1062                 // Clears all pending transactions and converts them to messages to be forwarded to a new leader.
1063                 Collection<?> messagesToForward = commitCoordinator.convertPendingTransactionsToMessages(
1064                     datastoreContext.getShardBatchedModificationCount());
1065
1066                 if (!messagesToForward.isEmpty()) {
1067                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
1068                             messagesToForward.size(), leader);
1069
1070                     for (Object message : messagesToForward) {
1071                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
1072
1073                         leader.tell(message, self());
1074                     }
1075                 }
1076             } else {
1077                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
1078                         + "change and the leader address isn't available.", this);
1079             }
1080         } else {
1081             // We have become the leader, we need to reconstruct frontend state
1082             knownFrontends = verifyNotNull(frontendMetadata.toLeaderState(this));
1083             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
1084         }
1085
1086         if (!isIsolatedLeader()) {
1087             messageRetrySupport.retryMessages();
1088         }
1089     }
1090
1091     @Override
1092     protected final void pauseLeader(final Runnable operation) {
1093         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
1094         paused = true;
1095
1096         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
1097         if (datastoreContext.isUseTellBasedProtocol()) {
1098             knownFrontends.values().forEach(LeaderFrontendState::retire);
1099             knownFrontends = ImmutableMap.of();
1100         }
1101
1102         store.setRunOnPendingTransactionsComplete(operation);
1103     }
1104
1105     @Override
1106     protected final void unpauseLeader() {
1107         LOG.debug("{}: In unpauseLeader", persistenceId());
1108         paused = false;
1109
1110         store.setRunOnPendingTransactionsComplete(null);
1111
1112         // Restore tell-based protocol state as if we were becoming the leader
1113         knownFrontends = verifyNotNull(frontendMetadata.toLeaderState(this));
1114     }
1115
1116     @Override
1117     protected final OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
1118         return OnDemandShardState.newBuilder()
1119             .treeChangeListenerActors(treeChangeSupport.getListenerActors())
1120             .commitCohortActors(store.getCohortActors());
1121     }
1122
1123     @Override
1124     public final String persistenceId() {
1125         return name;
1126     }
1127
1128     @Override
1129     public final String journalPluginId() {
1130         // This method may be invoked from super constructor (wonderful), hence we also need to handle the case of
1131         // the field being uninitialized because our constructor is not finished.
1132         if (datastoreContext != null && !datastoreContext.isPersistent()) {
1133             return NON_PERSISTENT_JOURNAL_ID;
1134         }
1135         return super.journalPluginId();
1136     }
1137
1138     @VisibleForTesting
1139     final ShardCommitCoordinator getCommitCoordinator() {
1140         return commitCoordinator;
1141     }
1142
1143     // non-final for mocking
1144     DatastoreContext getDatastoreContext() {
1145         return datastoreContext;
1146     }
1147
1148     @VisibleForTesting
1149     final ShardDataTree getDataStore() {
1150         return store;
1151     }
1152
1153     @VisibleForTesting
1154     // non-final for mocking
1155     ShardStats getShardMBean() {
1156         return shardMBean;
1157     }
1158
1159     public static Builder builder() {
1160         return new Builder();
1161     }
1162
1163     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1164         private final Class<? extends S> shardClass;
1165         private ShardIdentifier id;
1166         private Map<String, String> peerAddresses = Collections.emptyMap();
1167         private DatastoreContext datastoreContext;
1168         private EffectiveModelContextProvider schemaContextProvider;
1169         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1170         private DataTree dataTree;
1171
1172         private volatile boolean sealed;
1173
1174         AbstractBuilder(final Class<? extends S> shardClass) {
1175             this.shardClass = shardClass;
1176         }
1177
1178         final void checkSealed() {
1179             checkState(!sealed, "Builder is already sealed - further modifications are not allowed");
1180         }
1181
1182         @SuppressWarnings("unchecked")
1183         private T self() {
1184             return (T) this;
1185         }
1186
1187         public T id(final ShardIdentifier newId) {
1188             checkSealed();
1189             this.id = newId;
1190             return self();
1191         }
1192
1193         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1194             checkSealed();
1195             this.peerAddresses = newPeerAddresses;
1196             return self();
1197         }
1198
1199         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1200             checkSealed();
1201             this.datastoreContext = newDatastoreContext;
1202             return self();
1203         }
1204
1205         public T schemaContextProvider(final EffectiveModelContextProvider newSchemaContextProvider) {
1206             checkSealed();
1207             this.schemaContextProvider = requireNonNull(newSchemaContextProvider);
1208             return self();
1209         }
1210
1211         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1212             checkSealed();
1213             this.restoreFromSnapshot = newRestoreFromSnapshot;
1214             return self();
1215         }
1216
1217         public T dataTree(final DataTree newDataTree) {
1218             checkSealed();
1219             this.dataTree = newDataTree;
1220             return self();
1221         }
1222
1223         public ShardIdentifier getId() {
1224             return id;
1225         }
1226
1227         public Map<String, String> getPeerAddresses() {
1228             return peerAddresses;
1229         }
1230
1231         public DatastoreContext getDatastoreContext() {
1232             return datastoreContext;
1233         }
1234
1235         public EffectiveModelContext getSchemaContext() {
1236             return verifyNotNull(schemaContextProvider.getEffectiveModelContext());
1237         }
1238
1239         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1240             return restoreFromSnapshot;
1241         }
1242
1243         public DataTree getDataTree() {
1244             return dataTree;
1245         }
1246
1247         public TreeType getTreeType() {
1248             switch (datastoreContext.getLogicalStoreType()) {
1249                 case CONFIGURATION:
1250                     return TreeType.CONFIGURATION;
1251                 case OPERATIONAL:
1252                     return TreeType.OPERATIONAL;
1253                 default:
1254                     throw new IllegalStateException("Unhandled logical store type "
1255                             + datastoreContext.getLogicalStoreType());
1256             }
1257         }
1258
1259         protected void verify() {
1260             requireNonNull(id, "id should not be null");
1261             requireNonNull(peerAddresses, "peerAddresses should not be null");
1262             requireNonNull(datastoreContext, "dataStoreContext should not be null");
1263             requireNonNull(schemaContextProvider, "schemaContextProvider should not be null");
1264         }
1265
1266         public Props props() {
1267             sealed = true;
1268             verify();
1269             return Props.create(shardClass, this);
1270         }
1271     }
1272
1273     public static class Builder extends AbstractBuilder<Builder, Shard> {
1274         Builder() {
1275             this(Shard.class);
1276         }
1277
1278         Builder(final Class<? extends Shard> shardClass) {
1279             super(shardClass);
1280         }
1281     }
1282
1283     Ticker ticker() {
1284         return Ticker.systemTicker();
1285     }
1286
1287     void scheduleNextPendingTransaction() {
1288         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1289     }
1290 }