opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/Shard.java

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.controller.cluster.datastore;
   9
  10 import static com.google.common.base.Verify.verify;
  11
  12 import akka.actor.ActorRef;
  13 import akka.actor.ActorSelection;
  14 import akka.actor.Cancellable;
  15 import akka.actor.ExtendedActorSystem;
  16 import akka.actor.Props;
  17 import akka.actor.Status;
  18 import akka.actor.Status.Failure;
  19 import akka.serialization.JavaSerializer;
  20 import akka.serialization.Serialization;
  21 import com.google.common.annotations.VisibleForTesting;
  22 import com.google.common.base.Optional;
  23 import com.google.common.base.Preconditions;
  24 import com.google.common.base.Ticker;
  25 import com.google.common.base.Verify;
  26 import com.google.common.collect.ImmutableList;
  27 import com.google.common.collect.ImmutableMap;
  28 import com.google.common.collect.Range;
  29 import java.io.IOException;
  30 import java.util.Arrays;
  31 import java.util.Collection;
  32 import java.util.Collections;
  33 import java.util.HashMap;
  34 import java.util.Map;
  35 import java.util.concurrent.TimeUnit;
  36 import org.eclipse.jdt.annotation.NonNull;
  37 import org.eclipse.jdt.annotation.Nullable;
  38 import org.opendaylight.controller.cluster.access.ABIVersion;
  39 import org.opendaylight.controller.cluster.access.commands.ConnectClientRequest;
  40 import org.opendaylight.controller.cluster.access.commands.ConnectClientSuccess;
  41 import org.opendaylight.controller.cluster.access.commands.LocalHistoryRequest;
  42 import org.opendaylight.controller.cluster.access.commands.NotLeaderException;
  43 import org.opendaylight.controller.cluster.access.commands.OutOfSequenceEnvelopeException;
  44 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
  45 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  46 import org.opendaylight.controller.cluster.access.concepts.FrontendIdentifier;
  47 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
  48 import org.opendaylight.controller.cluster.access.concepts.Request;
  49 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
  50 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  51 import org.opendaylight.controller.cluster.access.concepts.RequestSuccess;
  52 import org.opendaylight.controller.cluster.access.concepts.RetiredGenerationException;
  53 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
  54 import org.opendaylight.controller.cluster.access.concepts.SliceableMessage;
  55 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  56 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
  57 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
  58 import org.opendaylight.controller.cluster.common.actor.Dispatchers;
  59 import org.opendaylight.controller.cluster.common.actor.Dispatchers.DispatcherType;
  60 import org.opendaylight.controller.cluster.common.actor.MessageTracker;
  61 import org.opendaylight.controller.cluster.common.actor.MessageTracker.Error;
  62 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
  63 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  64 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  65 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardDataTreeListenerInfoMXBeanImpl;
  66 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardMBeanFactory;
  67 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
  68 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
  69 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
  70 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  71 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransaction;
  72 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  73 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
  74 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  75 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  76 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
  77 import org.opendaylight.controller.cluster.datastore.messages.GetShardDataTree;
  78 import org.opendaylight.controller.cluster.datastore.messages.MakeLeaderLocal;
  79 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
  80 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
  81 import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
  82 import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
  83 import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
  84 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
  85 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot;
  86 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot.ShardSnapshot;
  87 import org.opendaylight.controller.cluster.datastore.persisted.DisableTrackingPayload;
  88 import org.opendaylight.controller.cluster.messaging.MessageAssembler;
  89 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
  90 import org.opendaylight.controller.cluster.messaging.SliceOptions;
  91 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
  92 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
  93 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
  94 import org.opendaylight.controller.cluster.raft.LeadershipTransferFailedException;
  95 import org.opendaylight.controller.cluster.raft.RaftActor;
  96 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
  97 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
  98 import org.opendaylight.controller.cluster.raft.RaftState;
  99 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
 100 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
 101 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
 102 import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
 103 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
 104 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
 105 import org.opendaylight.yangtools.concepts.Identifier;
 106 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
 107 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
 108 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
 109 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
 110 import org.opendaylight.yangtools.yang.model.api.SchemaContextProvider;
 111 import scala.concurrent.duration.FiniteDuration;
 112
 113 /**
 114  * A Shard represents a portion of the logical data tree.
 115  *
 116  * <p>
 117  * Our Shard uses InMemoryDataTree as it's internal representation and delegates all requests it
 118  */
 119 public class Shard extends RaftActor {
 120
 121     @VisibleForTesting
 122     static final Object TX_COMMIT_TIMEOUT_CHECK_MESSAGE = new Object() {
 123         @Override
 124         public String toString() {
 125             return "txCommitTimeoutCheck";
 126         }
 127     };
 128
 129     @VisibleForTesting
 130     static final Object GET_SHARD_MBEAN_MESSAGE = new Object() {
 131         @Override
 132         public String toString() {
 133             return "getShardMBeanMessage";
 134         }
 135     };
 136
 137     static final Object RESUME_NEXT_PENDING_TRANSACTION = new Object() {
 138         @Override
 139         public String toString() {
 140             return "resumeNextPendingTransaction";
 141         }
 142     };
 143
 144     // FIXME: shard names should be encapsulated in their own class and this should be exposed as a constant.
 145     public static final String DEFAULT_NAME = "default";
 146
 147     private static final Collection<ABIVersion> SUPPORTED_ABIVERSIONS;
 148
 149     static {
 150         final ABIVersion[] values = ABIVersion.values();
 151         final ABIVersion[] real = Arrays.copyOfRange(values, 1, values.length - 1);
 152         SUPPORTED_ABIVERSIONS = ImmutableList.copyOf(real).reverse();
 153     }
 154
 155     // FIXME: make this a dynamic property based on mailbox size and maximum number of clients
 156     private static final int CLIENT_MAX_MESSAGES = 1000;
 157
 158     // The state of this Shard
 159     private final ShardDataTree store;
 160
 161     /// The name of this shard
 162     private final String name;
 163
 164     private final String shardName;
 165
 166     private final ShardStats shardMBean;
 167
 168     private final ShardDataTreeListenerInfoMXBeanImpl listenerInfoMXBean;
 169
 170     private DatastoreContext datastoreContext;
 171
 172     private final ShardCommitCoordinator commitCoordinator;
 173
 174     private long transactionCommitTimeout;
 175
 176     private Cancellable txCommitTimeoutCheckSchedule;
 177
 178     private final Optional<ActorRef> roleChangeNotifier;
 179
 180     private final MessageTracker appendEntriesReplyTracker;
 181
 182     private final ShardTransactionActorFactory transactionActorFactory;
 183
 184     private final ShardSnapshotCohort snapshotCohort;
 185
 186     private final DataTreeChangeListenerSupport treeChangeSupport = new DataTreeChangeListenerSupport(this);
 187
 188     private ShardSnapshot restoreFromSnapshot;
 189
 190     private final ShardTransactionMessageRetrySupport messageRetrySupport;
 191
 192     private final FrontendMetadata frontendMetadata;
 193     private Map<FrontendIdentifier, LeaderFrontendState> knownFrontends = ImmutableMap.of();
 194     private boolean paused;
 195
 196     private final MessageSlicer responseMessageSlicer;
 197     private final Dispatchers dispatchers;
 198
 199     private final MessageAssembler requestMessageAssembler;
 200
 201     protected Shard(final AbstractBuilder<?, ?> builder) {
 202         super(builder.getId().toString(), builder.getPeerAddresses(),
 203                 Optional.of(builder.getDatastoreContext().getShardRaftConfig()), DataStoreVersions.CURRENT_VERSION);
 204
 205         this.name = builder.getId().toString();
 206         this.shardName = builder.getId().getShardName();
 207         this.datastoreContext = builder.getDatastoreContext();
 208         this.restoreFromSnapshot = builder.getRestoreFromSnapshot();
 209         this.frontendMetadata = new FrontendMetadata(name);
 210
 211         setPersistence(datastoreContext.isPersistent());
 212
 213         LOG.info("Shard created : {}, persistent : {}", name, datastoreContext.isPersistent());
 214
 215         ShardDataTreeChangeListenerPublisherActorProxy treeChangeListenerPublisher =
 216                 new ShardDataTreeChangeListenerPublisherActorProxy(getContext(), name + "-DTCL-publisher", name);
 217         if (builder.getDataTree() != null) {
 218             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getDataTree(),
 219                     treeChangeListenerPublisher, name, frontendMetadata);
 220         } else {
 221             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getTreeType(),
 222                     builder.getDatastoreContext().getStoreRoot(), treeChangeListenerPublisher, name, frontendMetadata);
 223         }
 224
 225         shardMBean = ShardMBeanFactory.getShardStatsMBean(name, datastoreContext.getDataStoreMXBeanType(), this);
 226
 227         if (isMetricsCaptureEnabled()) {
 228             getContext().become(new MeteringBehavior(this));
 229         }
 230
 231         commitCoordinator = new ShardCommitCoordinator(store, LOG, this.name);
 232
 233         setTransactionCommitTimeout();
 234
 235         // create a notifier actor for each cluster member
 236         roleChangeNotifier = createRoleChangeNotifier(name);
 237
 238         appendEntriesReplyTracker = new MessageTracker(AppendEntriesReply.class,
 239                 getRaftActorContext().getConfigParams().getIsolatedCheckIntervalInMillis());
 240
 241         dispatchers = new Dispatchers(context().system().dispatchers());
 242         transactionActorFactory = new ShardTransactionActorFactory(store, datastoreContext,
 243             dispatchers.getDispatcherPath(Dispatchers.DispatcherType.Transaction),
 244                 self(), getContext(), shardMBean, builder.getId().getShardName());
 245
 246         snapshotCohort = ShardSnapshotCohort.create(getContext(), builder.getId().getMemberName(), store, LOG,
 247             this.name);
 248
 249         messageRetrySupport = new ShardTransactionMessageRetrySupport(this);
 250
 251         responseMessageSlicer = MessageSlicer.builder().logContext(this.name)
 252                 .messageSliceSize(datastoreContext.getMaximumMessageSliceSize())
 253                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 254                 .expireStateAfterInactivity(2, TimeUnit.MINUTES).build();
 255
 256         requestMessageAssembler = MessageAssembler.builder().logContext(this.name)
 257                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 258                 .assembledMessageCallback((message, sender) -> self().tell(message, sender))
 259                 .expireStateAfterInactivity(datastoreContext.getRequestTimeout(), TimeUnit.NANOSECONDS).build();
 260
 261         listenerInfoMXBean = new ShardDataTreeListenerInfoMXBeanImpl(name, datastoreContext.getDataStoreMXBeanType(),
 262                 self());
 263         listenerInfoMXBean.register();
 264     }
 265
 266     private void setTransactionCommitTimeout() {
 267         transactionCommitTimeout = TimeUnit.MILLISECONDS.convert(
 268                 datastoreContext.getShardTransactionCommitTimeoutInSeconds(), TimeUnit.SECONDS) / 2;
 269     }
 270
 271     private Optional<ActorRef> createRoleChangeNotifier(final String shardId) {
 272         ActorRef shardRoleChangeNotifier = this.getContext().actorOf(
 273             RoleChangeNotifier.getProps(shardId), shardId + "-notifier");
 274         return Optional.of(shardRoleChangeNotifier);
 275     }
 276
 277     @Override
 278     public void postStop() {
 279         LOG.info("Stopping Shard {}", persistenceId());
 280
 281         super.postStop();
 282
 283         messageRetrySupport.close();
 284
 285         if (txCommitTimeoutCheckSchedule != null) {
 286             txCommitTimeoutCheckSchedule.cancel();
 287         }
 288
 289         commitCoordinator.abortPendingTransactions("Transaction aborted due to shutdown.", this);
 290
 291         shardMBean.unregisterMBean();
 292         listenerInfoMXBean.unregister();
 293     }
 294
 295     @Override
 296     protected void handleRecover(final Object message) {
 297         LOG.debug("{}: onReceiveRecover: Received message {} from {}", persistenceId(), message.getClass(),
 298             getSender());
 299
 300         super.handleRecover(message);
 301         if (LOG.isTraceEnabled()) {
 302             appendEntriesReplyTracker.begin();
 303         }
 304     }
 305
 306     @Override
 307     protected void handleNonRaftCommand(final Object message) {
 308         try (MessageTracker.Context context = appendEntriesReplyTracker.received(message)) {
 309             final Optional<Error> maybeError = context.error();
 310             if (maybeError.isPresent()) {
 311                 LOG.trace("{} : AppendEntriesReply failed to arrive at the expected interval {}", persistenceId(),
 312                     maybeError.get());
 313             }
 314
 315             store.resetTransactionBatch();
 316
 317             if (message instanceof RequestEnvelope) {
 318                 handleRequestEnvelope((RequestEnvelope)message);
 319             } else if (MessageAssembler.isHandledMessage(message)) {
 320                 handleRequestAssemblerMessage(message);
 321             } else if (message instanceof ConnectClientRequest) {
 322                 handleConnectClient((ConnectClientRequest)message);
 323             } else if (CreateTransaction.isSerializedType(message)) {
 324                 handleCreateTransaction(message);
 325             } else if (message instanceof BatchedModifications) {
 326                 handleBatchedModifications((BatchedModifications)message);
 327             } else if (message instanceof ForwardedReadyTransaction) {
 328                 handleForwardedReadyTransaction((ForwardedReadyTransaction) message);
 329             } else if (message instanceof ReadyLocalTransaction) {
 330                 handleReadyLocalTransaction((ReadyLocalTransaction)message);
 331             } else if (CanCommitTransaction.isSerializedType(message)) {
 332                 handleCanCommitTransaction(CanCommitTransaction.fromSerializable(message));
 333             } else if (CommitTransaction.isSerializedType(message)) {
 334                 handleCommitTransaction(CommitTransaction.fromSerializable(message));
 335             } else if (AbortTransaction.isSerializedType(message)) {
 336                 handleAbortTransaction(AbortTransaction.fromSerializable(message));
 337             } else if (CloseTransactionChain.isSerializedType(message)) {
 338                 closeTransactionChain(CloseTransactionChain.fromSerializable(message));
 339             } else if (message instanceof RegisterDataTreeChangeListener) {
 340                 treeChangeSupport.onMessage((RegisterDataTreeChangeListener) message, isLeader(), hasLeader());
 341             } else if (message instanceof UpdateSchemaContext) {
 342                 updateSchemaContext((UpdateSchemaContext) message);
 343             } else if (message instanceof PeerAddressResolved) {
 344                 PeerAddressResolved resolved = (PeerAddressResolved) message;
 345                 setPeerAddress(resolved.getPeerId(), resolved.getPeerAddress());
 346             } else if (TX_COMMIT_TIMEOUT_CHECK_MESSAGE.equals(message)) {
 347                 commitTimeoutCheck();
 348             } else if (message instanceof DatastoreContext) {
 349                 onDatastoreContext((DatastoreContext)message);
 350             } else if (message instanceof RegisterRoleChangeListener) {
 351                 roleChangeNotifier.get().forward(message, context());
 352             } else if (message instanceof FollowerInitialSyncUpStatus) {
 353                 shardMBean.setFollowerInitialSyncStatus(((FollowerInitialSyncUpStatus) message).isInitialSyncDone());
 354                 context().parent().tell(message, self());
 355             } else if (GET_SHARD_MBEAN_MESSAGE.equals(message)) {
 356                 sender().tell(getShardMBean(), self());
 357             } else if (message instanceof GetShardDataTree) {
 358                 sender().tell(store.getDataTree(), self());
 359             } else if (message instanceof ServerRemoved) {
 360                 context().parent().forward(message, context());
 361             } else if (ShardTransactionMessageRetrySupport.TIMER_MESSAGE_CLASS.isInstance(message)) {
 362                 messageRetrySupport.onTimerMessage(message);
 363             } else if (message instanceof DataTreeCohortActorRegistry.CohortRegistryCommand) {
 364                 store.processCohortRegistryCommand(getSender(),
 365                         (DataTreeCohortActorRegistry.CohortRegistryCommand) message);
 366             } else if (message instanceof MakeLeaderLocal) {
 367                 onMakeLeaderLocal();
 368             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
 369                 store.resumeNextPendingTransaction();
 370             } else if (!responseMessageSlicer.handleMessage(message)) {
 371                 super.handleNonRaftCommand(message);
 372             }
 373         }
 374     }
 375
 376     private void handleRequestAssemblerMessage(final Object message) {
 377         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
 378             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
 379             requestMessageAssembler.handleMessage(message, self());
 380         });
 381     }
 382
 383     @SuppressWarnings("checkstyle:IllegalCatch")
 384     private void handleRequestEnvelope(final RequestEnvelope envelope) {
 385         final long now = ticker().read();
 386         try {
 387             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
 388             if (success != null) {
 389                 final long executionTimeNanos = ticker().read() - now;
 390                 if (success instanceof SliceableMessage) {
 391                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
 392                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
 393                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
 394                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
 395                             .onFailureCallback(t -> LOG.warn("Error slicing response {}", success, t)).build()));
 396                 } else {
 397                     envelope.sendSuccess(success, executionTimeNanos);
 398                 }
 399             }
 400         } catch (RequestException e) {
 401             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
 402             envelope.sendFailure(e, ticker().read() - now);
 403         } catch (Exception e) {
 404             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
 405             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
 406                 ticker().read() - now);
 407         }
 408     }
 409
 410     private void commitTimeoutCheck() {
 411         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
 412         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
 413         requestMessageAssembler.checkExpiredAssembledMessageState();
 414     }
 415
 416     private Optional<Long> updateAccess(final SimpleShardDataTreeCohort cohort) {
 417         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
 418         final LeaderFrontendState state = knownFrontends.get(frontend);
 419         if (state == null) {
 420             // Not tell-based protocol, do nothing
 421             return Optional.absent();
 422         }
 423
 424         if (isIsolatedLeader()) {
 425             // We are isolated and no new request can come through until we emerge from it. We are still updating
 426             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
 427             return Optional.of(state.getLastSeenTicks());
 428         }
 429
 430         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
 431         return Optional.of(state.getLastConnectTicks());
 432     }
 433
 434     private void disableTracking(final DisableTrackingPayload payload) {
 435         final ClientIdentifier clientId = payload.getIdentifier();
 436         LOG.debug("{}: disabling tracking of {}", persistenceId(), clientId);
 437         frontendMetadata.disableTracking(clientId);
 438
 439         if (isLeader()) {
 440             final FrontendIdentifier frontendId = clientId.getFrontendId();
 441             final LeaderFrontendState frontend = knownFrontends.get(frontendId);
 442             if (frontend != null) {
 443                 if (clientId.equals(frontend.getIdentifier())) {
 444                     if (!(frontend instanceof LeaderFrontendState.Disabled)) {
 445                         verify(knownFrontends.replace(frontendId, frontend,
 446                             new LeaderFrontendState.Disabled(persistenceId(), clientId, store)));
 447                         LOG.debug("{}: leader state for {} disabled", persistenceId(), clientId);
 448                     } else {
 449                         LOG.debug("{}: leader state {} is already disabled", persistenceId(), frontend);
 450                     }
 451                 } else {
 452                     LOG.debug("{}: leader state {} does not match {}", persistenceId(), frontend, clientId);
 453                 }
 454             } else {
 455                 LOG.debug("{}: leader state for {} not found", persistenceId(), clientId);
 456                 knownFrontends.put(frontendId, new LeaderFrontendState.Disabled(persistenceId(), clientId,
 457                     getDataStore()));
 458             }
 459         }
 460     }
 461
 462     private void onMakeLeaderLocal() {
 463         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
 464         if (isLeader()) {
 465             getSender().tell(new Status.Success(null), getSelf());
 466             return;
 467         }
 468
 469         final ActorSelection leader = getLeader();
 470
 471         if (leader == null) {
 472             // Leader is not present. The cluster is most likely trying to
 473             // elect a leader and we should let that run its normal course
 474
 475             // TODO we can wait for the election to complete and retry the
 476             // request. We can also let the caller retry by sending a flag
 477             // in the response indicating the request is "reTryable".
 478             getSender().tell(new Failure(
 479                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
 480                             + "Currently there is no leader for " + persistenceId())),
 481                     getSelf());
 482             return;
 483         }
 484
 485         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
 486     }
 487
 488     // Acquire our frontend tracking handle and verify generation matches
 489     private @Nullable LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
 490         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
 491         if (existing != null) {
 492             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
 493             if (cmp == 0) {
 494                 existing.touch();
 495                 return existing;
 496             }
 497             if (cmp > 0) {
 498                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
 499                 throw new RetiredGenerationException(clientId.getGeneration(),
 500                     existing.getIdentifier().getGeneration());
 501             }
 502
 503             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 504             existing.retire();
 505             knownFrontends.remove(clientId.getFrontendId());
 506         } else {
 507             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 508         }
 509
 510         return null;
 511     }
 512
 513     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 514         final LeaderFrontendState ret = findFrontend(clientId);
 515         if (ret != null) {
 516             return ret;
 517         }
 518
 519         // TODO: a dedicated exception would be better, but this is technically true, too
 520         throw new OutOfSequenceEnvelopeException(0);
 521     }
 522
 523     private static @NonNull ABIVersion selectVersion(final ConnectClientRequest message) {
 524         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
 525         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
 526             if (clientRange.contains(v)) {
 527                 return v;
 528             }
 529         }
 530
 531         throw new IllegalArgumentException(String.format(
 532             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
 533             clientRange));
 534     }
 535
 536     @SuppressWarnings("checkstyle:IllegalCatch")
 537     private void handleConnectClient(final ConnectClientRequest message) {
 538         try {
 539             final ClientIdentifier clientId = message.getTarget();
 540             final LeaderFrontendState existing = findFrontend(clientId);
 541             if (existing != null) {
 542                 existing.touch();
 543             }
 544
 545             if (!isLeader() || !isLeaderActive()) {
 546                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 547                                 + "isLeadershipTransferInProgress: {}.",
 548                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
 549                 throw new NotLeaderException(getSelf());
 550             }
 551
 552             final ABIVersion selectedVersion = selectVersion(message);
 553             final LeaderFrontendState frontend;
 554             if (existing == null) {
 555                 frontend = new LeaderFrontendState.Enabled(persistenceId(), clientId, store);
 556                 knownFrontends.put(clientId.getFrontendId(), frontend);
 557                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
 558             } else {
 559                 frontend = existing;
 560             }
 561
 562             frontend.reconnect();
 563             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
 564                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
 565                 ActorRef.noSender());
 566         } catch (RequestException | RuntimeException e) {
 567             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
 568         }
 569     }
 570
 571     private @Nullable RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 572             throws RequestException {
 573         // We are not the leader, hence we want to fail-fast.
 574         if (!isLeader() || paused || !isLeaderActive()) {
 575             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 576                             + "isLeadershipTransferInProgress: {}, paused: {}",
 577                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 578             throw new NotLeaderException(getSelf());
 579         }
 580
 581         final Request<?, ?> request = envelope.getMessage();
 582         if (request instanceof TransactionRequest) {
 583             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
 584             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
 585             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 586         } else if (request instanceof LocalHistoryRequest) {
 587             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
 588             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
 589             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 590         } else {
 591             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 592             throw new UnsupportedRequestException(request);
 593         }
 594     }
 595
 596     private boolean hasLeader() {
 597         return getLeaderId() != null;
 598     }
 599
 600     public int getPendingTxCommitQueueSize() {
 601         return store.getQueueSize();
 602     }
 603
 604     public int getCohortCacheSize() {
 605         return commitCoordinator.getCohortCacheSize();
 606     }
 607
 608     @Override
 609     protected Optional<ActorRef> getRoleChangeNotifier() {
 610         return roleChangeNotifier;
 611     }
 612
 613     String getShardName() {
 614         return shardName;
 615     }
 616
 617     @Override
 618     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 619             final short leaderPayloadVersion) {
 620         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 621                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 622     }
 623
 624     protected void onDatastoreContext(final DatastoreContext context) {
 625         datastoreContext = context;
 626
 627         setTransactionCommitTimeout();
 628
 629         setPersistence(datastoreContext.isPersistent());
 630
 631         updateConfigParams(datastoreContext.getShardRaftConfig());
 632     }
 633
 634     // applyState() will be invoked once consensus is reached on the payload
 635     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 636         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 637         if (canSkipPayload) {
 638             applyState(self(), id, payload);
 639         } else {
 640             // We are faking the sender
 641             persistData(self(), id, payload, batchHint);
 642         }
 643     }
 644
 645     private void handleCommitTransaction(final CommitTransaction commit) {
 646         final TransactionIdentifier txId = commit.getTransactionId();
 647         if (isLeader()) {
 648             askProtocolEncountered(txId);
 649             commitCoordinator.handleCommit(txId, getSender(), this);
 650         } else {
 651             ActorSelection leader = getLeader();
 652             if (leader == null) {
 653                 messageRetrySupport.addMessageToRetry(commit, getSender(), "Could not commit transaction " + txId);
 654             } else {
 655                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 656                 leader.forward(commit, getContext());
 657             }
 658         }
 659     }
 660
 661     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 662         final TransactionIdentifier txId = canCommit.getTransactionId();
 663         LOG.debug("{}: Can committing transaction {}", persistenceId(), txId);
 664
 665         if (isLeader()) {
 666             askProtocolEncountered(txId);
 667             commitCoordinator.handleCanCommit(txId, getSender(), this);
 668         } else {
 669             ActorSelection leader = getLeader();
 670             if (leader == null) {
 671                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 672                         "Could not canCommit transaction " + txId);
 673             } else {
 674                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 675                 leader.forward(canCommit, getContext());
 676             }
 677         }
 678     }
 679
 680     @SuppressWarnings("checkstyle:IllegalCatch")
 681     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 682         askProtocolEncountered(batched.getTransactionId());
 683
 684         try {
 685             commitCoordinator.handleBatchedModifications(batched, sender, this);
 686         } catch (Exception e) {
 687             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 688                     batched.getTransactionId(), e);
 689             sender.tell(new Failure(e), getSelf());
 690         }
 691     }
 692
 693     private void handleBatchedModifications(final BatchedModifications batched) {
 694         // This message is sent to prepare the modifications transaction directly on the Shard as an
 695         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 696         // BatchedModifications message, the caller sets the ready flag in the message indicating
 697         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 698         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 699         // ReadyTransaction message.
 700
 701         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 702         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 703         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 704         // window where it could have a stale leader during leadership transitions.
 705         //
 706         boolean isLeaderActive = isLeaderActive();
 707         if (isLeader() && isLeaderActive) {
 708             handleBatchedModificationsLocal(batched, getSender());
 709         } else {
 710             ActorSelection leader = getLeader();
 711             if (!isLeaderActive || leader == null) {
 712                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 713                         "Could not process BatchedModifications " + batched.getTransactionId());
 714             } else {
 715                 // If this is not the first batch and leadership changed in between batched messages,
 716                 // we need to reconstruct previous BatchedModifications from the transaction
 717                 // DataTreeModification, honoring the max batched modification count, and forward all the
 718                 // previous BatchedModifications to the new leader.
 719                 Collection<BatchedModifications> newModifications = commitCoordinator
 720                         .createForwardedBatchedModifications(batched,
 721                                 datastoreContext.getShardBatchedModificationCount());
 722
 723                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 724                         newModifications.size(), leader);
 725
 726                 for (BatchedModifications bm : newModifications) {
 727                     leader.forward(bm, getContext());
 728                 }
 729             }
 730         }
 731     }
 732
 733     private boolean failIfIsolatedLeader(final ActorRef sender) {
 734         if (isIsolatedLeader()) {
 735             sender.tell(new Failure(new NoShardLeaderException(String.format(
 736                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 737                     + " other follower nodes are down or this node is isolated by a network partition.",
 738                     persistenceId()))), getSelf());
 739             return true;
 740         }
 741
 742         return false;
 743     }
 744
 745     protected boolean isIsolatedLeader() {
 746         return getRaftState() == RaftState.IsolatedLeader;
 747     }
 748
 749     @SuppressWarnings("checkstyle:IllegalCatch")
 750     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 751         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
 752
 753         boolean isLeaderActive = isLeaderActive();
 754         if (isLeader() && isLeaderActive) {
 755             try {
 756                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 757             } catch (Exception e) {
 758                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
 759                         message.getTransactionId(), e);
 760                 getSender().tell(new Failure(e), getSelf());
 761             }
 762         } else {
 763             ActorSelection leader = getLeader();
 764             if (!isLeaderActive || leader == null) {
 765                 messageRetrySupport.addMessageToRetry(message, getSender(),
 766                         "Could not process ready local transaction " + message.getTransactionId());
 767             } else {
 768                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 769                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 770                 leader.forward(message, getContext());
 771             }
 772         }
 773     }
 774
 775     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 776         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 777
 778         boolean isLeaderActive = isLeaderActive();
 779         if (isLeader() && isLeaderActive) {
 780             askProtocolEncountered(forwardedReady.getTransactionId());
 781             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 782         } else {
 783             ActorSelection leader = getLeader();
 784             if (!isLeaderActive || leader == null) {
 785                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 786                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 787             } else {
 788                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 789
 790                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 791                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 792                         forwardedReady.getParticipatingShardNames());
 793                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 794                 leader.forward(readyLocal, getContext());
 795             }
 796         }
 797     }
 798
 799     private void handleAbortTransaction(final AbortTransaction abort) {
 800         final TransactionIdentifier transactionId = abort.getTransactionId();
 801         askProtocolEncountered(transactionId);
 802         doAbortTransaction(transactionId, getSender());
 803     }
 804
 805     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 806         commitCoordinator.handleAbort(transactionID, sender, this);
 807     }
 808
 809     private void handleCreateTransaction(final Object message) {
 810         if (isLeader()) {
 811             createTransaction(CreateTransaction.fromSerializable(message));
 812         } else if (getLeader() != null) {
 813             getLeader().forward(message, getContext());
 814         } else {
 815             getSender().tell(new Failure(new NoShardLeaderException(
 816                     "Could not create a shard transaction", persistenceId())), getSelf());
 817         }
 818     }
 819
 820     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 821         if (isLeader()) {
 822             final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 823             askProtocolEncountered(id.getClientId());
 824
 825             // FIXME: CONTROLLER-1628: stage purge once no transactions are present
 826             store.closeTransactionChain(id, null);
 827             store.purgeTransactionChain(id, null);
 828         } else if (getLeader() != null) {
 829             getLeader().forward(closeTransactionChain, getContext());
 830         } else {
 831             LOG.warn("{}: Could not close transaction {}", persistenceId(), closeTransactionChain.getIdentifier());
 832         }
 833     }
 834
 835     @SuppressWarnings("checkstyle:IllegalCatch")
 836     private void createTransaction(final CreateTransaction createTransaction) {
 837         askProtocolEncountered(createTransaction.getTransactionId());
 838
 839         try {
 840             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
 841                     && failIfIsolatedLeader(getSender())) {
 842                 return;
 843             }
 844
 845             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 846                 createTransaction.getTransactionId());
 847
 848             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 849                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 850         } catch (Exception e) {
 851             getSender().tell(new Failure(e), getSelf());
 852         }
 853     }
 854
 855     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
 856         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 857         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 858             transactionId);
 859     }
 860
 861     // Called on leader only
 862     private void askProtocolEncountered(final TransactionIdentifier transactionId) {
 863         askProtocolEncountered(transactionId.getHistoryId().getClientId());
 864     }
 865
 866     // Called on leader only
 867     private void askProtocolEncountered(final ClientIdentifier clientId) {
 868         final FrontendIdentifier frontend = clientId.getFrontendId();
 869         final LeaderFrontendState state = knownFrontends.get(frontend);
 870         if (!(state instanceof LeaderFrontendState.Disabled)) {
 871             LOG.debug("{}: encountered ask-based client {}, disabling transaction tracking", persistenceId(), clientId);
 872             if (knownFrontends.isEmpty()) {
 873                 knownFrontends = new HashMap<>();
 874             }
 875             knownFrontends.put(frontend, new LeaderFrontendState.Disabled(persistenceId(), clientId, getDataStore()));
 876
 877             persistPayload(clientId, DisableTrackingPayload.create(clientId,
 878                 datastoreContext.getInitialPayloadSerializedBufferCapacity()), false);
 879         }
 880     }
 881
 882     private void updateSchemaContext(final UpdateSchemaContext message) {
 883         updateSchemaContext(message.getSchemaContext());
 884     }
 885
 886     @VisibleForTesting
 887     void updateSchemaContext(final SchemaContext schemaContext) {
 888         store.updateSchemaContext(schemaContext);
 889     }
 890
 891     private boolean isMetricsCaptureEnabled() {
 892         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 893         return config.isMetricCaptureEnabled();
 894     }
 895
 896     @Override
 897     @VisibleForTesting
 898     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 899         return snapshotCohort;
 900     }
 901
 902     @Override
 903     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 904         if (restoreFromSnapshot == null) {
 905             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 906         }
 907
 908         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 909     }
 910
 911     @Override
 912     protected void onRecoveryComplete() {
 913         restoreFromSnapshot = null;
 914
 915         //notify shard manager
 916         getContext().parent().tell(new ActorInitialized(), getSelf());
 917
 918         // Being paranoid here - this method should only be called once but just in case...
 919         if (txCommitTimeoutCheckSchedule == null) {
 920             // Schedule a message to be periodically sent to check if the current in-progress
 921             // transaction should be expired and aborted.
 922             FiniteDuration period = FiniteDuration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 923             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 924                     period, period, getSelf(),
 925                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 926         }
 927     }
 928
 929     @Override
 930     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 931         if (data instanceof Payload) {
 932             if (data instanceof DisableTrackingPayload) {
 933                 disableTracking((DisableTrackingPayload) data);
 934                 return;
 935             }
 936
 937             try {
 938                 store.applyReplicatedPayload(identifier, (Payload)data);
 939             } catch (DataValidationFailedException | IOException e) {
 940                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 941             }
 942         } else {
 943             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
 944         }
 945     }
 946
 947     @Override
 948     protected void onStateChanged() {
 949         boolean isLeader = isLeader();
 950         boolean hasLeader = hasLeader();
 951         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
 952
 953         // If this actor is no longer the leader close all the transaction chains
 954         if (!isLeader) {
 955             if (LOG.isDebugEnabled()) {
 956                 LOG.debug(
 957                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
 958                     persistenceId(), getId());
 959             }
 960
 961             paused = false;
 962             store.purgeLeaderState();
 963         }
 964
 965         if (hasLeader && !isIsolatedLeader()) {
 966             messageRetrySupport.retryMessages();
 967         }
 968     }
 969
 970     @Override
 971     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
 972         shardMBean.incrementLeadershipChangeCount();
 973         paused = false;
 974
 975         if (!isLeader()) {
 976             if (!knownFrontends.isEmpty()) {
 977                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
 978                 knownFrontends = ImmutableMap.of();
 979             }
 980
 981             requestMessageAssembler.close();
 982
 983             if (!hasLeader()) {
 984                 // No leader anywhere, nothing else to do
 985                 return;
 986             }
 987
 988             // Another leader was elected. If we were the previous leader and had pending transactions, convert
 989             // them to transaction messages and send to the new leader.
 990             ActorSelection leader = getLeader();
 991             if (leader != null) {
 992                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
 993
 994                 if (!messagesToForward.isEmpty()) {
 995                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
 996                             messagesToForward.size(), leader);
 997
 998                     for (Object message : messagesToForward) {
 999                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
1000
1001                         leader.tell(message, self());
1002                     }
1003                 }
1004             } else {
1005                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
1006                         + "change and the leader address isn't available.", this);
1007             }
1008         } else {
1009             // We have become the leader, we need to reconstruct frontend state
1010             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
1011             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
1012         }
1013
1014         if (!isIsolatedLeader()) {
1015             messageRetrySupport.retryMessages();
1016         }
1017     }
1018
1019     /**
1020      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
1021      *
1022      * @return the converted messages
1023      */
1024     public Collection<?> convertPendingTransactionsToMessages() {
1025         return commitCoordinator.convertPendingTransactionsToMessages(
1026                 datastoreContext.getShardBatchedModificationCount());
1027     }
1028
1029     @Override
1030     protected void pauseLeader(final Runnable operation) {
1031         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
1032         paused = true;
1033
1034         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
1035         if (datastoreContext.isUseTellBasedProtocol()) {
1036             knownFrontends.values().forEach(LeaderFrontendState::retire);
1037             knownFrontends = ImmutableMap.of();
1038         }
1039
1040         store.setRunOnPendingTransactionsComplete(operation);
1041     }
1042
1043     @Override
1044     protected void unpauseLeader() {
1045         LOG.debug("{}: In unpauseLeader", persistenceId());
1046         paused = false;
1047
1048         store.setRunOnPendingTransactionsComplete(null);
1049
1050         // Restore tell-based protocol state as if we were becoming the leader
1051         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
1052     }
1053
1054     @Override
1055     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
1056         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
1057                 .commitCohortActors(store.getCohortActors());
1058     }
1059
1060     @Override
1061     public String persistenceId() {
1062         return this.name;
1063     }
1064
1065     @VisibleForTesting
1066     ShardCommitCoordinator getCommitCoordinator() {
1067         return commitCoordinator;
1068     }
1069
1070     public DatastoreContext getDatastoreContext() {
1071         return datastoreContext;
1072     }
1073
1074     @VisibleForTesting
1075     public ShardDataTree getDataStore() {
1076         return store;
1077     }
1078
1079     @VisibleForTesting
1080     ShardStats getShardMBean() {
1081         return shardMBean;
1082     }
1083
1084     public static Builder builder() {
1085         return new Builder();
1086     }
1087
1088     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1089         private final Class<S> shardClass;
1090         private ShardIdentifier id;
1091         private Map<String, String> peerAddresses = Collections.emptyMap();
1092         private DatastoreContext datastoreContext;
1093         private SchemaContextProvider schemaContextProvider;
1094         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1095         private DataTree dataTree;
1096         private volatile boolean sealed;
1097
1098         protected AbstractBuilder(final Class<S> shardClass) {
1099             this.shardClass = shardClass;
1100         }
1101
1102         protected void checkSealed() {
1103             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1104         }
1105
1106         @SuppressWarnings("unchecked")
1107         private T self() {
1108             return (T) this;
1109         }
1110
1111         public T id(final ShardIdentifier newId) {
1112             checkSealed();
1113             this.id = newId;
1114             return self();
1115         }
1116
1117         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1118             checkSealed();
1119             this.peerAddresses = newPeerAddresses;
1120             return self();
1121         }
1122
1123         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1124             checkSealed();
1125             this.datastoreContext = newDatastoreContext;
1126             return self();
1127         }
1128
1129         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1130             checkSealed();
1131             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1132             return self();
1133         }
1134
1135         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1136             checkSealed();
1137             this.restoreFromSnapshot = newRestoreFromSnapshot;
1138             return self();
1139         }
1140
1141         public T dataTree(final DataTree newDataTree) {
1142             checkSealed();
1143             this.dataTree = newDataTree;
1144             return self();
1145         }
1146
1147         public ShardIdentifier getId() {
1148             return id;
1149         }
1150
1151         public Map<String, String> getPeerAddresses() {
1152             return peerAddresses;
1153         }
1154
1155         public DatastoreContext getDatastoreContext() {
1156             return datastoreContext;
1157         }
1158
1159         public SchemaContext getSchemaContext() {
1160             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1161         }
1162
1163         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1164             return restoreFromSnapshot;
1165         }
1166
1167         public DataTree getDataTree() {
1168             return dataTree;
1169         }
1170
1171         public TreeType getTreeType() {
1172             switch (datastoreContext.getLogicalStoreType()) {
1173                 case CONFIGURATION:
1174                     return TreeType.CONFIGURATION;
1175                 case OPERATIONAL:
1176                     return TreeType.OPERATIONAL;
1177                 default:
1178                     throw new IllegalStateException("Unhandled logical store type "
1179                             + datastoreContext.getLogicalStoreType());
1180             }
1181         }
1182
1183         protected void verify() {
1184             Preconditions.checkNotNull(id, "id should not be null");
1185             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1186             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1187             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1188         }
1189
1190         public Props props() {
1191             sealed = true;
1192             verify();
1193             return Props.create(shardClass, this);
1194         }
1195     }
1196
1197     public static class Builder extends AbstractBuilder<Builder, Shard> {
1198         Builder() {
1199             super(Shard.class);
1200         }
1201     }
1202
1203     Ticker ticker() {
1204         return Ticker.systemTicker();
1205     }
1206
1207     void scheduleNextPendingTransaction() {
1208         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1209     }
1210 }