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.RequestEnvelope;
  56 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  57 import org.opendaylight.controller.cluster.access.concepts.RequestSuccess;
  58 import org.opendaylight.controller.cluster.access.concepts.RetiredGenerationException;
  59 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
  60 import org.opendaylight.controller.cluster.access.concepts.SliceableMessage;
  61 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  62 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
  63 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
  64 import org.opendaylight.controller.cluster.common.actor.Dispatchers;
  65 import org.opendaylight.controller.cluster.common.actor.Dispatchers.DispatcherType;
  66 import org.opendaylight.controller.cluster.common.actor.MessageTracker;
  67 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
  68 import org.opendaylight.controller.cluster.datastore.actors.JsonExportActor;
  69 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  70 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  71 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
  72 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
  73 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  74 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransaction;
  75 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  76 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
  77 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  78 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  79 import org.opendaylight.controller.cluster.datastore.messages.DataTreeChangedReply;
  80 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
  81 import org.opendaylight.controller.cluster.datastore.messages.GetKnownClients;
  82 import org.opendaylight.controller.cluster.datastore.messages.GetKnownClientsReply;
  83 import org.opendaylight.controller.cluster.datastore.messages.GetShardDataTree;
  84 import org.opendaylight.controller.cluster.datastore.messages.MakeLeaderLocal;
  85 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
  86 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
  87 import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
  88 import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
  89 import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
  90 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
  91 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot;
  92 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot.ShardSnapshot;
  93 import org.opendaylight.controller.cluster.datastore.persisted.DisableTrackingPayload;
  94 import org.opendaylight.controller.cluster.messaging.MessageAssembler;
  95 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
  96 import org.opendaylight.controller.cluster.messaging.SliceOptions;
  97 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
  98 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
  99 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
 100 import org.opendaylight.controller.cluster.raft.LeadershipTransferFailedException;
 101 import org.opendaylight.controller.cluster.raft.RaftActor;
 102 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
 103 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
 104 import org.opendaylight.controller.cluster.raft.RaftState;
 105 import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry;
 106 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
 107 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
 108 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
 109 import org.opendaylight.controller.cluster.raft.messages.Payload;
 110 import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
 111 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
 112 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.controller.config.distributed.datastore.provider.rev231229.DataStoreProperties.ExportOnRecovery;
 113 import org.opendaylight.yangtools.concepts.Identifier;
 114 import org.opendaylight.yangtools.yang.data.tree.api.DataTree;
 115 import org.opendaylight.yangtools.yang.data.tree.api.DataValidationFailedException;
 116 import org.opendaylight.yangtools.yang.data.tree.api.TreeType;
 117 import org.opendaylight.yangtools.yang.model.api.EffectiveModelContext;
 118 import org.opendaylight.yangtools.yang.model.api.EffectiveModelContextProvider;
 119 import scala.concurrent.duration.FiniteDuration;
 120
 121 /**
 122  * A Shard represents a portion of the logical data tree.
 123  *
 124  * <p>
 125  * Our Shard uses InMemoryDataTree as it's internal representation and delegates all requests it
 126  */
 127 // FIXME: non-final for testing?
 128 public class Shard extends RaftActor {
 129
 130     @VisibleForTesting
 131     static final Object TX_COMMIT_TIMEOUT_CHECK_MESSAGE = new Object() {
 132         @Override
 133         public String toString() {
 134             return "txCommitTimeoutCheck";
 135         }
 136     };
 137
 138     @VisibleForTesting
 139     static final Object GET_SHARD_MBEAN_MESSAGE = new Object() {
 140         @Override
 141         public String toString() {
 142             return "getShardMBeanMessage";
 143         }
 144     };
 145
 146     static final Object RESUME_NEXT_PENDING_TRANSACTION = new Object() {
 147         @Override
 148         public String toString() {
 149             return "resumeNextPendingTransaction";
 150         }
 151     };
 152
 153     // FIXME: shard names should be encapsulated in their own class and this should be exposed as a constant.
 154     public static final String DEFAULT_NAME = "default";
 155
 156     private static final Collection<ABIVersion> SUPPORTED_ABIVERSIONS;
 157
 158     // Make sure to keep this in sync with the journal configuration in factory-akka.conf
 159     public static final String NON_PERSISTENT_JOURNAL_ID = "akka.persistence.non-persistent.journal";
 160
 161     static {
 162         final ABIVersion[] values = ABIVersion.values();
 163         final ABIVersion[] real = Arrays.copyOfRange(values, 1, values.length - 1);
 164         SUPPORTED_ABIVERSIONS = ImmutableList.copyOf(real).reverse();
 165     }
 166
 167     // FIXME: make this a dynamic property based on mailbox size and maximum number of clients
 168     private static final int CLIENT_MAX_MESSAGES = 1000;
 169
 170     // The state of this Shard
 171     private final ShardDataTree store;
 172
 173     /// The name of this shard
 174     private final String name;
 175
 176     private final String shardName;
 177
 178     private final ShardStats shardMBean;
 179
 180     private final ShardDataTreeListenerInfoMXBeanImpl listenerInfoMXBean;
 181
 182     private DatastoreContext datastoreContext;
 183
 184     private final ShardCommitCoordinator commitCoordinator;
 185
 186     private long transactionCommitTimeout;
 187
 188     private Cancellable txCommitTimeoutCheckSchedule;
 189
 190     private final Optional<ActorRef> roleChangeNotifier;
 191
 192     private final MessageTracker appendEntriesReplyTracker;
 193
 194     private final ShardTransactionActorFactory transactionActorFactory;
 195
 196     private final ShardSnapshotCohort snapshotCohort;
 197
 198     private final DataTreeChangeListenerSupport treeChangeSupport = new DataTreeChangeListenerSupport(this);
 199
 200     private ShardSnapshot restoreFromSnapshot;
 201
 202     private final ShardTransactionMessageRetrySupport messageRetrySupport;
 203
 204     @VisibleForTesting
 205     final FrontendMetadata frontendMetadata;
 206
 207     private Map<FrontendIdentifier, LeaderFrontendState> knownFrontends = ImmutableMap.of();
 208     private boolean paused;
 209
 210     private final MessageSlicer responseMessageSlicer;
 211     private final Dispatchers dispatchers;
 212
 213     private final MessageAssembler requestMessageAssembler;
 214
 215     private final ExportOnRecovery exportOnRecovery;
 216
 217     private final ActorRef exportActor;
 218
 219     @SuppressFBWarnings(value = "MC_OVERRIDABLE_METHOD_CALL_IN_CONSTRUCTOR", justification = "Akka class design")
 220     Shard(final AbstractBuilder<?, ?> builder) {
 221         super(builder.getId().toString(), builder.getPeerAddresses(),
 222                 Optional.of(builder.getDatastoreContext().getShardRaftConfig()), DataStoreVersions.CURRENT_VERSION);
 223
 224         name = builder.getId().toString();
 225         shardName = builder.getId().getShardName();
 226         datastoreContext = builder.getDatastoreContext();
 227         restoreFromSnapshot = builder.getRestoreFromSnapshot();
 228         frontendMetadata = new FrontendMetadata(name);
 229         exportOnRecovery = datastoreContext.getExportOnRecovery();
 230
 231         exportActor = switch (exportOnRecovery) {
 232             case Json -> getContext().actorOf(JsonExportActor.props(builder.getSchemaContext(),
 233                 datastoreContext.getRecoveryExportBaseDir()));
 234             case Off -> null;
 235         };
 236
 237         setPersistence(datastoreContext.isPersistent());
 238
 239         LOG.info("Shard created : {}, persistent : {}", name, datastoreContext.isPersistent());
 240
 241         ShardDataTreeChangeListenerPublisherActorProxy treeChangeListenerPublisher =
 242                 new ShardDataTreeChangeListenerPublisherActorProxy(getContext(), name + "-DTCL-publisher", name);
 243         if (builder.getDataTree() != null) {
 244             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getDataTree(),
 245                     treeChangeListenerPublisher, name,
 246                     frontendMetadata);
 247         } else {
 248             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getTreeType(),
 249                     builder.getDatastoreContext().getStoreRoot(), treeChangeListenerPublisher, name,
 250                     frontendMetadata);
 251         }
 252
 253         shardMBean = ShardStats.create(name, datastoreContext.getDataStoreMXBeanType(), this);
 254
 255         if (isMetricsCaptureEnabled()) {
 256             getContext().become(new MeteringBehavior(this));
 257         }
 258
 259         commitCoordinator = new ShardCommitCoordinator(store, LOG, name);
 260
 261         setTransactionCommitTimeout();
 262
 263         // create a notifier actor for each cluster member
 264         roleChangeNotifier = createRoleChangeNotifier(name);
 265
 266         appendEntriesReplyTracker = new MessageTracker(AppendEntriesReply.class,
 267                 getRaftActorContext().getConfigParams().getIsolatedCheckIntervalInMillis());
 268
 269         dispatchers = new Dispatchers(context().system().dispatchers());
 270         transactionActorFactory = new ShardTransactionActorFactory(store, datastoreContext,
 271             dispatchers.getDispatcherPath(Dispatchers.DispatcherType.Transaction),
 272                 self(), getContext(), shardMBean, builder.getId().getShardName());
 273
 274         snapshotCohort = ShardSnapshotCohort.create(getContext(), builder.getId().getMemberName(), store, LOG,
 275             name, datastoreContext);
 276
 277         messageRetrySupport = new ShardTransactionMessageRetrySupport(this);
 278
 279         responseMessageSlicer = MessageSlicer.builder().logContext(name)
 280                 .messageSliceSize(datastoreContext.getMaximumMessageSliceSize())
 281                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 282                 .expireStateAfterInactivity(2, TimeUnit.MINUTES).build();
 283
 284         requestMessageAssembler = MessageAssembler.builder().logContext(name)
 285                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 286                 .assembledMessageCallback((message, sender) -> self().tell(message, sender))
 287                 .expireStateAfterInactivity(datastoreContext.getRequestTimeout(), TimeUnit.NANOSECONDS).build();
 288
 289         listenerInfoMXBean = new ShardDataTreeListenerInfoMXBeanImpl(name, datastoreContext.getDataStoreMXBeanType(),
 290                 self());
 291         listenerInfoMXBean.register();
 292     }
 293
 294     private void setTransactionCommitTimeout() {
 295         transactionCommitTimeout = TimeUnit.MILLISECONDS.convert(
 296                 datastoreContext.getShardTransactionCommitTimeoutInSeconds(), TimeUnit.SECONDS) / 2;
 297     }
 298
 299     private Optional<ActorRef> createRoleChangeNotifier(final String shardId) {
 300         ActorRef shardRoleChangeNotifier = getContext().actorOf(
 301             RoleChangeNotifier.getProps(shardId), shardId + "-notifier");
 302         return Optional.of(shardRoleChangeNotifier);
 303     }
 304
 305     @Override
 306     public final void postStop() throws Exception {
 307         LOG.info("Stopping Shard {}", persistenceId());
 308
 309         super.postStop();
 310
 311         messageRetrySupport.close();
 312
 313         if (txCommitTimeoutCheckSchedule != null) {
 314             txCommitTimeoutCheckSchedule.cancel();
 315         }
 316
 317         commitCoordinator.abortPendingTransactions("Transaction aborted due to shutdown.", this);
 318
 319         shardMBean.unregisterMBean();
 320         listenerInfoMXBean.unregister();
 321     }
 322
 323     @Override
 324     protected final void handleRecover(final Object message) {
 325         LOG.debug("{}: onReceiveRecover: Received message {} from {}", persistenceId(), message.getClass(),
 326             getSender());
 327
 328         super.handleRecover(message);
 329
 330         switch (exportOnRecovery) {
 331             case Json:
 332                 if (message instanceof SnapshotOffer) {
 333                     exportActor.tell(new JsonExportActor.ExportSnapshot(store.readCurrentData().orElseThrow(), name),
 334                             ActorRef.noSender());
 335                 } else if (message instanceof ReplicatedLogEntry replicatedLogEntry) {
 336                     exportActor.tell(new JsonExportActor.ExportJournal(replicatedLogEntry), ActorRef.noSender());
 337                 } else if (message instanceof RecoveryCompleted) {
 338                     exportActor.tell(new JsonExportActor.FinishExport(name), ActorRef.noSender());
 339                     exportActor.tell(PoisonPill.getInstance(), ActorRef.noSender());
 340                 }
 341                 break;
 342             case Off:
 343             default:
 344                 break;
 345         }
 346
 347         if (LOG.isTraceEnabled()) {
 348             appendEntriesReplyTracker.begin();
 349         }
 350     }
 351
 352     @Override
 353     // non-final for TestShard
 354     protected void handleNonRaftCommand(final Object message) {
 355         try (var context = appendEntriesReplyTracker.received(message)) {
 356             final var maybeError = context.error();
 357             if (maybeError.isPresent()) {
 358                 LOG.trace("{} : AppendEntriesReply failed to arrive at the expected interval {}", persistenceId(),
 359                     maybeError.orElseThrow());
 360             }
 361
 362             store.resetTransactionBatch();
 363
 364             if (message instanceof RequestEnvelope request) {
 365                 handleRequestEnvelope(request);
 366             } else if (MessageAssembler.isHandledMessage(message)) {
 367                 handleRequestAssemblerMessage(message);
 368             } else if (message instanceof ConnectClientRequest request) {
 369                 handleConnectClient(request);
 370             } else if (CreateTransaction.isSerializedType(message)) {
 371                 handleCreateTransaction(message);
 372             } else if (message instanceof BatchedModifications request) {
 373                 handleBatchedModifications(request);
 374             } else if (message instanceof ForwardedReadyTransaction request) {
 375                 handleForwardedReadyTransaction(request);
 376             } else if (message instanceof ReadyLocalTransaction request) {
 377                 handleReadyLocalTransaction(request);
 378             } else if (CanCommitTransaction.isSerializedType(message)) {
 379                 handleCanCommitTransaction(CanCommitTransaction.fromSerializable(message));
 380             } else if (CommitTransaction.isSerializedType(message)) {
 381                 handleCommitTransaction(CommitTransaction.fromSerializable(message));
 382             } else if (AbortTransaction.isSerializedType(message)) {
 383                 handleAbortTransaction(AbortTransaction.fromSerializable(message));
 384             } else if (CloseTransactionChain.isSerializedType(message)) {
 385                 closeTransactionChain(CloseTransactionChain.fromSerializable(message));
 386             } else if (message instanceof DataTreeChangedReply) {
 387                 // Ignore reply
 388             } else if (message instanceof RegisterDataTreeChangeListener request) {
 389                 treeChangeSupport.onMessage(request, isLeader(), hasLeader());
 390             } else if (message instanceof UpdateSchemaContext request) {
 391                 updateSchemaContext(request);
 392             } else if (message instanceof PeerAddressResolved resolved) {
 393                 setPeerAddress(resolved.getPeerId(), resolved.getPeerAddress());
 394             } else if (TX_COMMIT_TIMEOUT_CHECK_MESSAGE.equals(message)) {
 395                 commitTimeoutCheck();
 396             } else if (message instanceof DatastoreContext request) {
 397                 onDatastoreContext(request);
 398             } else if (message instanceof RegisterRoleChangeListener) {
 399                 roleChangeNotifier.orElseThrow().forward(message, context());
 400             } else if (message instanceof FollowerInitialSyncUpStatus request) {
 401                 shardMBean.setFollowerInitialSyncStatus(request.isInitialSyncDone());
 402                 context().parent().tell(message, self());
 403             } else if (GET_SHARD_MBEAN_MESSAGE.equals(message)) {
 404                 sender().tell(getShardMBean(), self());
 405             } else if (message instanceof GetShardDataTree) {
 406                 sender().tell(store.getDataTree(), self());
 407             } else if (message instanceof ServerRemoved) {
 408                 context().parent().forward(message, context());
 409             } else if (ShardTransactionMessageRetrySupport.TIMER_MESSAGE_CLASS.isInstance(message)) {
 410                 messageRetrySupport.onTimerMessage(message);
 411             } else if (message instanceof DataTreeCohortActorRegistry.CohortRegistryCommand request) {
 412                 store.processCohortRegistryCommand(getSender(), request);
 413             } else if (message instanceof MakeLeaderLocal) {
 414                 onMakeLeaderLocal();
 415             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
 416                 store.resumeNextPendingTransaction();
 417             } else if (GetKnownClients.INSTANCE.equals(message)) {
 418                 handleGetKnownClients();
 419             } else if (!responseMessageSlicer.handleMessage(message)) {
 420                 super.handleNonRaftCommand(message);
 421             }
 422         }
 423     }
 424
 425     private void handleRequestAssemblerMessage(final Object message) {
 426         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
 427             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
 428             requestMessageAssembler.handleMessage(message, self());
 429         });
 430     }
 431
 432     @SuppressWarnings("checkstyle:IllegalCatch")
 433     private void handleRequestEnvelope(final RequestEnvelope envelope) {
 434         final long now = ticker().read();
 435         try {
 436             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
 437             if (success != null) {
 438                 final long executionTimeNanos = ticker().read() - now;
 439                 if (success instanceof SliceableMessage) {
 440                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
 441                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
 442                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
 443                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
 444                             .onFailureCallback(t -> LOG.warn("Error slicing response {}", success, t)).build()));
 445                 } else {
 446                     envelope.sendSuccess(success, executionTimeNanos);
 447                 }
 448             }
 449         } catch (RequestException e) {
 450             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
 451             envelope.sendFailure(e, ticker().read() - now);
 452         } catch (Exception e) {
 453             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
 454             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
 455                 ticker().read() - now);
 456         }
 457     }
 458
 459     private void commitTimeoutCheck() {
 460         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
 461         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
 462         requestMessageAssembler.checkExpiredAssembledMessageState();
 463     }
 464
 465     private OptionalLong updateAccess(final SimpleShardDataTreeCohort cohort) {
 466         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
 467         final LeaderFrontendState state = knownFrontends.get(frontend);
 468         if (state == null) {
 469             // Not tell-based protocol, do nothing
 470             return OptionalLong.empty();
 471         }
 472
 473         if (isIsolatedLeader()) {
 474             // We are isolated and no new request can come through until we emerge from it. We are still updating
 475             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
 476             return OptionalLong.of(state.getLastSeenTicks());
 477         }
 478
 479         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
 480         return OptionalLong.of(state.getLastConnectTicks());
 481     }
 482
 483     private void disableTracking(final DisableTrackingPayload payload) {
 484         final ClientIdentifier clientId = payload.getIdentifier();
 485         LOG.debug("{}: disabling tracking of {}", persistenceId(), clientId);
 486         frontendMetadata.disableTracking(clientId);
 487
 488         if (isLeader()) {
 489             final FrontendIdentifier frontendId = clientId.getFrontendId();
 490             final LeaderFrontendState frontend = knownFrontends.get(frontendId);
 491             if (frontend != null) {
 492                 if (clientId.equals(frontend.getIdentifier())) {
 493                     if (!(frontend instanceof LeaderFrontendState.Disabled)) {
 494                         verify(knownFrontends.replace(frontendId, frontend,
 495                             new LeaderFrontendState.Disabled(persistenceId(), clientId, store)));
 496                         LOG.debug("{}: leader state for {} disabled", persistenceId(), clientId);
 497                     } else {
 498                         LOG.debug("{}: leader state {} is already disabled", persistenceId(), frontend);
 499                     }
 500                 } else {
 501                     LOG.debug("{}: leader state {} does not match {}", persistenceId(), frontend, clientId);
 502                 }
 503             } else {
 504                 LOG.debug("{}: leader state for {} not found", persistenceId(), clientId);
 505                 knownFrontends.put(frontendId, new LeaderFrontendState.Disabled(persistenceId(), clientId,
 506                     getDataStore()));
 507             }
 508         }
 509     }
 510
 511     private void onMakeLeaderLocal() {
 512         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
 513         if (isLeader()) {
 514             getSender().tell(new Status.Success(null), getSelf());
 515             return;
 516         }
 517
 518         final ActorSelection leader = getLeader();
 519
 520         if (leader == null) {
 521             // Leader is not present. The cluster is most likely trying to
 522             // elect a leader and we should let that run its normal course
 523
 524             // TODO we can wait for the election to complete and retry the
 525             // request. We can also let the caller retry by sending a flag
 526             // in the response indicating the request is "reTryable".
 527             getSender().tell(new Failure(
 528                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
 529                             + "Currently there is no leader for " + persistenceId())),
 530                     getSelf());
 531             return;
 532         }
 533
 534         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
 535     }
 536
 537     // Acquire our frontend tracking handle and verify generation matches
 538     private @Nullable LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
 539         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
 540         if (existing != null) {
 541             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
 542             if (cmp == 0) {
 543                 existing.touch();
 544                 return existing;
 545             }
 546             if (cmp > 0) {
 547                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
 548                 throw new RetiredGenerationException(clientId.getGeneration(),
 549                     existing.getIdentifier().getGeneration());
 550             }
 551
 552             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 553             existing.retire();
 554             knownFrontends.remove(clientId.getFrontendId());
 555         } else {
 556             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 557         }
 558
 559         return null;
 560     }
 561
 562     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 563         final LeaderFrontendState ret = findFrontend(clientId);
 564         if (ret != null) {
 565             return ret;
 566         }
 567
 568         // TODO: a dedicated exception would be better, but this is technically true, too
 569         throw new OutOfSequenceEnvelopeException(0);
 570     }
 571
 572     private static @NonNull ABIVersion selectVersion(final ConnectClientRequest message) {
 573         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
 574         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
 575             if (clientRange.contains(v)) {
 576                 return v;
 577             }
 578         }
 579
 580         throw new IllegalArgumentException(String.format(
 581             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
 582             clientRange));
 583     }
 584
 585     @SuppressWarnings("checkstyle:IllegalCatch")
 586     private void handleConnectClient(final ConnectClientRequest message) {
 587         try {
 588             final ClientIdentifier clientId = message.getTarget();
 589             final LeaderFrontendState existing = findFrontend(clientId);
 590             if (existing != null) {
 591                 existing.touch();
 592             }
 593
 594             if (!isLeader() || !isLeaderActive()) {
 595                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 596                                 + "isLeadershipTransferInProgress: {}.",
 597                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
 598                 throw new NotLeaderException(getSelf());
 599             }
 600
 601             final ABIVersion selectedVersion = selectVersion(message);
 602             final LeaderFrontendState frontend;
 603             if (existing == null) {
 604                 frontend = new LeaderFrontendState.Enabled(persistenceId(), clientId, store);
 605                 knownFrontends.put(clientId.getFrontendId(), frontend);
 606                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
 607             } else {
 608                 frontend = existing;
 609             }
 610
 611             frontend.reconnect();
 612             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
 613                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
 614                 ActorRef.noSender());
 615         } catch (RequestException | RuntimeException e) {
 616             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
 617         }
 618     }
 619
 620     private @Nullable RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 621             throws RequestException {
 622         // We are not the leader, hence we want to fail-fast.
 623         if (!isLeader() || paused || !isLeaderActive()) {
 624             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 625                             + "isLeadershipTransferInProgress: {}, paused: {}",
 626                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 627             throw new NotLeaderException(getSelf());
 628         }
 629
 630         final var request = envelope.getMessage();
 631         if (request instanceof TransactionRequest<?> txReq) {
 632             final var clientId = txReq.getTarget().getHistoryId().getClientId();
 633             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 634         } else if (request instanceof LocalHistoryRequest<?> lhReq) {
 635             final var clientId = lhReq.getTarget().getClientId();
 636             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 637         } else {
 638             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 639             throw new UnsupportedRequestException(request);
 640         }
 641     }
 642
 643     private void handleGetKnownClients() {
 644         final ImmutableSet<ClientIdentifier> clients;
 645         if (isLeader()) {
 646             clients = knownFrontends.values().stream()
 647                     .map(LeaderFrontendState::getIdentifier)
 648                     .collect(ImmutableSet.toImmutableSet());
 649         } else {
 650             clients = frontendMetadata.getClients();
 651         }
 652         sender().tell(new GetKnownClientsReply(clients), self());
 653     }
 654
 655     private boolean hasLeader() {
 656         return getLeaderId() != null;
 657     }
 658
 659     final int getPendingTxCommitQueueSize() {
 660         return store.getQueueSize();
 661     }
 662
 663     final int getCohortCacheSize() {
 664         return commitCoordinator.getCohortCacheSize();
 665     }
 666
 667     @Override
 668     protected final Optional<ActorRef> getRoleChangeNotifier() {
 669         return roleChangeNotifier;
 670     }
 671
 672     final String getShardName() {
 673         return shardName;
 674     }
 675
 676     @Override
 677     protected final LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 678             final short leaderPayloadVersion) {
 679         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 680                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 681     }
 682
 683     private void onDatastoreContext(final DatastoreContext context) {
 684         datastoreContext = verifyNotNull(context);
 685
 686         setTransactionCommitTimeout();
 687
 688         setPersistence(datastoreContext.isPersistent());
 689
 690         updateConfigParams(datastoreContext.getShardRaftConfig());
 691     }
 692
 693     // applyState() will be invoked once consensus is reached on the payload
 694     // non-final for mocking
 695     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 696         final boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 697         if (canSkipPayload) {
 698             applyState(self(), id, payload);
 699         } else {
 700             // We are faking the sender
 701             persistData(self(), id, payload, batchHint);
 702         }
 703     }
 704
 705     private void handleCommitTransaction(final CommitTransaction commit) {
 706         final TransactionIdentifier txId = commit.getTransactionId();
 707         if (isLeader()) {
 708             askProtocolEncountered(txId);
 709             commitCoordinator.handleCommit(txId, getSender(), this);
 710         } else {
 711             ActorSelection leader = getLeader();
 712             if (leader == null) {
 713                 messageRetrySupport.addMessageToRetry(commit, getSender(), "Could not commit transaction " + txId);
 714             } else {
 715                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 716                 leader.forward(commit, getContext());
 717             }
 718         }
 719     }
 720
 721     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 722         final TransactionIdentifier txId = canCommit.getTransactionId();
 723         LOG.debug("{}: Can committing transaction {}", persistenceId(), txId);
 724
 725         if (isLeader()) {
 726             askProtocolEncountered(txId);
 727             commitCoordinator.handleCanCommit(txId, getSender(), this);
 728         } else {
 729             ActorSelection leader = getLeader();
 730             if (leader == null) {
 731                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 732                         "Could not canCommit transaction " + txId);
 733             } else {
 734                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 735                 leader.forward(canCommit, getContext());
 736             }
 737         }
 738     }
 739
 740     @SuppressWarnings("checkstyle:IllegalCatch")
 741     private void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 742         askProtocolEncountered(batched.getTransactionId());
 743
 744         try {
 745             commitCoordinator.handleBatchedModifications(batched, sender, this);
 746         } catch (Exception e) {
 747             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 748                     batched.getTransactionId(), e);
 749             sender.tell(new Failure(e), getSelf());
 750         }
 751     }
 752
 753     private void handleBatchedModifications(final BatchedModifications batched) {
 754         // This message is sent to prepare the modifications transaction directly on the Shard as an
 755         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 756         // BatchedModifications message, the caller sets the ready flag in the message indicating
 757         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 758         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 759         // ReadyTransaction message.
 760
 761         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 762         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 763         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 764         // window where it could have a stale leader during leadership transitions.
 765         //
 766         boolean isLeaderActive = isLeaderActive();
 767         if (isLeader() && isLeaderActive) {
 768             handleBatchedModificationsLocal(batched, getSender());
 769         } else {
 770             ActorSelection leader = getLeader();
 771             if (!isLeaderActive || leader == null) {
 772                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 773                         "Could not process BatchedModifications " + batched.getTransactionId());
 774             } else {
 775                 // If this is not the first batch and leadership changed in between batched messages,
 776                 // we need to reconstruct previous BatchedModifications from the transaction
 777                 // DataTreeModification, honoring the max batched modification count, and forward all the
 778                 // previous BatchedModifications to the new leader.
 779                 Collection<BatchedModifications> newModifications = commitCoordinator
 780                         .createForwardedBatchedModifications(batched,
 781                                 datastoreContext.getShardBatchedModificationCount());
 782
 783                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 784                         newModifications.size(), leader);
 785
 786                 for (BatchedModifications bm : newModifications) {
 787                     leader.forward(bm, getContext());
 788                 }
 789             }
 790         }
 791     }
 792
 793     private boolean failIfIsolatedLeader(final ActorRef sender) {
 794         if (isIsolatedLeader()) {
 795             sender.tell(new Failure(new NoShardLeaderException(String.format(
 796                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 797                     + " other follower nodes are down or this node is isolated by a network partition.",
 798                     persistenceId()))), getSelf());
 799             return true;
 800         }
 801
 802         return false;
 803     }
 804
 805     protected boolean isIsolatedLeader() {
 806         return getRaftState() == RaftState.IsolatedLeader;
 807     }
 808
 809     @SuppressWarnings("checkstyle:IllegalCatch")
 810     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 811         final TransactionIdentifier txId = message.getTransactionId();
 812         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), txId);
 813
 814         boolean isLeaderActive = isLeaderActive();
 815         if (isLeader() && isLeaderActive) {
 816             askProtocolEncountered(txId);
 817             try {
 818                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 819             } catch (Exception e) {
 820                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(), txId, e);
 821                 getSender().tell(new Failure(e), getSelf());
 822             }
 823         } else {
 824             ActorSelection leader = getLeader();
 825             if (!isLeaderActive || leader == null) {
 826                 messageRetrySupport.addMessageToRetry(message, getSender(),
 827                         "Could not process ready local transaction " + txId);
 828             } else {
 829                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 830                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 831                 leader.forward(message, getContext());
 832             }
 833         }
 834     }
 835
 836     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 837         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 838
 839         boolean isLeaderActive = isLeaderActive();
 840         if (isLeader() && isLeaderActive) {
 841             askProtocolEncountered(forwardedReady.getTransactionId());
 842             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 843         } else {
 844             ActorSelection leader = getLeader();
 845             if (!isLeaderActive || leader == null) {
 846                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 847                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 848             } else {
 849                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 850
 851                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 852                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 853                         forwardedReady.getParticipatingShardNames());
 854                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 855                 leader.forward(readyLocal, getContext());
 856             }
 857         }
 858     }
 859
 860     private void handleAbortTransaction(final AbortTransaction abort) {
 861         final TransactionIdentifier transactionId = abort.getTransactionId();
 862         askProtocolEncountered(transactionId);
 863         doAbortTransaction(transactionId, getSender());
 864     }
 865
 866     final void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 867         commitCoordinator.handleAbort(transactionID, sender, this);
 868     }
 869
 870     private void handleCreateTransaction(final Object message) {
 871         if (isLeader()) {
 872             createTransaction(CreateTransaction.fromSerializable(message));
 873         } else if (getLeader() != null) {
 874             getLeader().forward(message, getContext());
 875         } else {
 876             getSender().tell(new Failure(new NoShardLeaderException(
 877                     "Could not create a shard transaction", persistenceId())), getSelf());
 878         }
 879     }
 880
 881     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 882         if (isLeader()) {
 883             final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 884             askProtocolEncountered(id.getClientId());
 885             store.closeTransactionChain(id);
 886         } else if (getLeader() != null) {
 887             getLeader().forward(closeTransactionChain, getContext());
 888         } else {
 889             LOG.warn("{}: Could not close transaction {}", persistenceId(), closeTransactionChain.getIdentifier());
 890         }
 891     }
 892
 893     @SuppressWarnings("checkstyle:IllegalCatch")
 894     private void createTransaction(final CreateTransaction createTransaction) {
 895         askProtocolEncountered(createTransaction.getTransactionId());
 896
 897         try {
 898             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
 899                     && failIfIsolatedLeader(getSender())) {
 900                 return;
 901             }
 902
 903             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 904                 createTransaction.getTransactionId());
 905
 906             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 907                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 908         } catch (Exception e) {
 909             getSender().tell(new Failure(e), getSelf());
 910         }
 911     }
 912
 913     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
 914         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 915         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 916             transactionId);
 917     }
 918
 919     // Called on leader only
 920     private void askProtocolEncountered(final TransactionIdentifier transactionId) {
 921         askProtocolEncountered(transactionId.getHistoryId().getClientId());
 922     }
 923
 924     // Called on leader only
 925     private void askProtocolEncountered(final ClientIdentifier clientId) {
 926         final FrontendIdentifier frontend = clientId.getFrontendId();
 927         final LeaderFrontendState state = knownFrontends.get(frontend);
 928         if (!(state instanceof LeaderFrontendState.Disabled)) {
 929             LOG.debug("{}: encountered ask-based client {}, disabling transaction tracking", persistenceId(), clientId);
 930             if (knownFrontends.isEmpty()) {
 931                 knownFrontends = new HashMap<>();
 932             }
 933             knownFrontends.put(frontend, new LeaderFrontendState.Disabled(persistenceId(), clientId, getDataStore()));
 934
 935             persistPayload(clientId, DisableTrackingPayload.create(clientId,
 936                 datastoreContext.getInitialPayloadSerializedBufferCapacity()), false);
 937         }
 938     }
 939
 940     private void updateSchemaContext(final UpdateSchemaContext message) {
 941         updateSchemaContext(message.getEffectiveModelContext());
 942     }
 943
 944     @VisibleForTesting
 945     void updateSchemaContext(final @NonNull EffectiveModelContext schemaContext) {
 946         store.updateSchemaContext(schemaContext);
 947     }
 948
 949     private boolean isMetricsCaptureEnabled() {
 950         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 951         return config.isMetricCaptureEnabled();
 952     }
 953
 954     @Override
 955     protected final RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 956         return snapshotCohort;
 957     }
 958
 959     @Override
 960     protected final RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 961         if (restoreFromSnapshot == null) {
 962             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 963         }
 964
 965         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 966     }
 967
 968     @Override
 969     // non-final for testing
 970     protected void onRecoveryComplete() {
 971         restoreFromSnapshot = null;
 972
 973         //notify shard manager
 974         getContext().parent().tell(new ActorInitialized(), getSelf());
 975
 976         // Being paranoid here - this method should only be called once but just in case...
 977         if (txCommitTimeoutCheckSchedule == null) {
 978             // Schedule a message to be periodically sent to check if the current in-progress
 979             // transaction should be expired and aborted.
 980             FiniteDuration period = FiniteDuration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 981             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 982                     period, period, getSelf(),
 983                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 984         }
 985     }
 986
 987     @Override
 988     protected final void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 989         if (data instanceof Payload payload) {
 990             if (payload instanceof DisableTrackingPayload disableTracking) {
 991                 disableTracking(disableTracking);
 992                 return;
 993             }
 994
 995             try {
 996                 store.applyReplicatedPayload(identifier, payload);
 997             } catch (DataValidationFailedException | IOException e) {
 998                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 999             }
1000         } else {
1001             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
1002         }
1003     }
1004
1005     @Override
1006     protected final void onStateChanged() {
1007         boolean isLeader = isLeader();
1008         boolean hasLeader = hasLeader();
1009         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
1010
1011         // If this actor is no longer the leader close all the transaction chains
1012         if (!isLeader) {
1013             if (LOG.isDebugEnabled()) {
1014                 LOG.debug(
1015                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
1016                     persistenceId(), getId());
1017             }
1018
1019             paused = false;
1020             store.purgeLeaderState();
1021         }
1022
1023         if (hasLeader && !isIsolatedLeader()) {
1024             messageRetrySupport.retryMessages();
1025         }
1026     }
1027
1028     @Override
1029     protected final void onLeaderChanged(final String oldLeader, final String newLeader) {
1030         shardMBean.incrementLeadershipChangeCount();
1031         paused = false;
1032
1033         if (!isLeader()) {
1034             if (!knownFrontends.isEmpty()) {
1035                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
1036                 knownFrontends = ImmutableMap.of();
1037             }
1038
1039             requestMessageAssembler.close();
1040
1041             if (!hasLeader()) {
1042                 // No leader anywhere, nothing else to do
1043                 return;
1044             }
1045
1046             // Another leader was elected. If we were the previous leader and had pending transactions, convert
1047             // them to transaction messages and send to the new leader.
1048             ActorSelection leader = getLeader();
1049             if (leader != null) {
1050                 // Clears all pending transactions and converts them to messages to be forwarded to a new leader.
1051                 Collection<?> messagesToForward = commitCoordinator.convertPendingTransactionsToMessages(
1052                     datastoreContext.getShardBatchedModificationCount());
1053
1054                 if (!messagesToForward.isEmpty()) {
1055                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
1056                             messagesToForward.size(), leader);
1057
1058                     for (Object message : messagesToForward) {
1059                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
1060
1061                         leader.tell(message, self());
1062                     }
1063                 }
1064             } else {
1065                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
1066                         + "change and the leader address isn't available.", this);
1067             }
1068         } else {
1069             // We have become the leader, we need to reconstruct frontend state
1070             knownFrontends = verifyNotNull(frontendMetadata.toLeaderState(this));
1071             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
1072         }
1073
1074         if (!isIsolatedLeader()) {
1075             messageRetrySupport.retryMessages();
1076         }
1077     }
1078
1079     @Override
1080     protected final void pauseLeader(final Runnable operation) {
1081         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
1082         paused = true;
1083
1084         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
1085         knownFrontends.values().forEach(LeaderFrontendState::retire);
1086         knownFrontends = ImmutableMap.of();
1087
1088         store.setRunOnPendingTransactionsComplete(operation);
1089     }
1090
1091     @Override
1092     protected final void unpauseLeader() {
1093         LOG.debug("{}: In unpauseLeader", persistenceId());
1094         paused = false;
1095
1096         store.setRunOnPendingTransactionsComplete(null);
1097
1098         // Restore tell-based protocol state as if we were becoming the leader
1099         knownFrontends = verifyNotNull(frontendMetadata.toLeaderState(this));
1100     }
1101
1102     @Override
1103     protected final OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
1104         return OnDemandShardState.newBuilder()
1105             .treeChangeListenerActors(treeChangeSupport.getListenerActors())
1106             .commitCohortActors(store.getCohortActors());
1107     }
1108
1109     @Override
1110     public final String persistenceId() {
1111         return name;
1112     }
1113
1114     @Override
1115     public final String journalPluginId() {
1116         // This method may be invoked from super constructor (wonderful), hence we also need to handle the case of
1117         // the field being uninitialized because our constructor is not finished.
1118         if (datastoreContext != null && !datastoreContext.isPersistent()) {
1119             return NON_PERSISTENT_JOURNAL_ID;
1120         }
1121         return super.journalPluginId();
1122     }
1123
1124     @VisibleForTesting
1125     final ShardCommitCoordinator getCommitCoordinator() {
1126         return commitCoordinator;
1127     }
1128
1129     // non-final for mocking
1130     DatastoreContext getDatastoreContext() {
1131         return datastoreContext;
1132     }
1133
1134     @VisibleForTesting
1135     final ShardDataTree getDataStore() {
1136         return store;
1137     }
1138
1139     @VisibleForTesting
1140     // non-final for mocking
1141     ShardStats getShardMBean() {
1142         return shardMBean;
1143     }
1144
1145     public static Builder builder() {
1146         return new Builder();
1147     }
1148
1149     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1150         private final Class<? extends S> shardClass;
1151         private ShardIdentifier id;
1152         private Map<String, String> peerAddresses = Collections.emptyMap();
1153         private DatastoreContext datastoreContext;
1154         private EffectiveModelContextProvider schemaContextProvider;
1155         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1156         private DataTree dataTree;
1157
1158         private volatile boolean sealed;
1159
1160         AbstractBuilder(final Class<? extends S> shardClass) {
1161             this.shardClass = shardClass;
1162         }
1163
1164         final void checkSealed() {
1165             checkState(!sealed, "Builder is already sealed - further modifications are not allowed");
1166         }
1167
1168         @SuppressWarnings("unchecked")
1169         private T self() {
1170             return (T) this;
1171         }
1172
1173         public T id(final ShardIdentifier newId) {
1174             checkSealed();
1175             id = newId;
1176             return self();
1177         }
1178
1179         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1180             checkSealed();
1181             peerAddresses = newPeerAddresses;
1182             return self();
1183         }
1184
1185         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1186             checkSealed();
1187             datastoreContext = newDatastoreContext;
1188             return self();
1189         }
1190
1191         public T schemaContextProvider(final EffectiveModelContextProvider newSchemaContextProvider) {
1192             checkSealed();
1193             schemaContextProvider = requireNonNull(newSchemaContextProvider);
1194             return self();
1195         }
1196
1197         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1198             checkSealed();
1199             restoreFromSnapshot = newRestoreFromSnapshot;
1200             return self();
1201         }
1202
1203         public T dataTree(final DataTree newDataTree) {
1204             checkSealed();
1205             dataTree = newDataTree;
1206             return self();
1207         }
1208
1209         public ShardIdentifier getId() {
1210             return id;
1211         }
1212
1213         public Map<String, String> getPeerAddresses() {
1214             return peerAddresses;
1215         }
1216
1217         public DatastoreContext getDatastoreContext() {
1218             return datastoreContext;
1219         }
1220
1221         public EffectiveModelContext getSchemaContext() {
1222             return verifyNotNull(schemaContextProvider.getEffectiveModelContext());
1223         }
1224
1225         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1226             return restoreFromSnapshot;
1227         }
1228
1229         public DataTree getDataTree() {
1230             return dataTree;
1231         }
1232
1233         public TreeType getTreeType() {
1234             return switch (datastoreContext.getLogicalStoreType()) {
1235                 case CONFIGURATION -> TreeType.CONFIGURATION;
1236                 case OPERATIONAL -> TreeType.OPERATIONAL;
1237             };
1238         }
1239
1240         protected void verify() {
1241             requireNonNull(id, "id should not be null");
1242             requireNonNull(peerAddresses, "peerAddresses should not be null");
1243             requireNonNull(datastoreContext, "dataStoreContext should not be null");
1244             requireNonNull(schemaContextProvider, "schemaContextProvider should not be null");
1245         }
1246
1247         public Props props() {
1248             sealed = true;
1249             verify();
1250             return Props.create(shardClass, this);
1251         }
1252     }
1253
1254     public static class Builder extends AbstractBuilder<Builder, Shard> {
1255         Builder() {
1256             this(Shard.class);
1257         }
1258
1259         Builder(final Class<? extends Shard> shardClass) {
1260             super(shardClass);
1261         }
1262     }
1263
1264     Ticker ticker() {
1265         return Ticker.systemTicker();
1266     }
1267
1268     void scheduleNextPendingTransaction() {
1269         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1270     }
1271 }