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