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