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.Map;
  34 import java.util.concurrent.TimeUnit;
  35 import javax.annotation.Nonnull;
  36 import javax.annotation.Nullable;
  37 import org.opendaylight.controller.cluster.access.ABIVersion;
  38 import org.opendaylight.controller.cluster.access.commands.ConnectClientRequest;
  39 import org.opendaylight.controller.cluster.access.commands.ConnectClientSuccess;
  40 import org.opendaylight.controller.cluster.access.commands.LocalHistoryRequest;
  41 import org.opendaylight.controller.cluster.access.commands.NotLeaderException;
  42 import org.opendaylight.controller.cluster.access.commands.OutOfSequenceEnvelopeException;
  43 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
  44 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  45 import org.opendaylight.controller.cluster.access.concepts.FrontendIdentifier;
  46 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
  47 import org.opendaylight.controller.cluster.access.concepts.Request;
  48 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
  49 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  50 import org.opendaylight.controller.cluster.access.concepts.RequestSuccess;
  51 import org.opendaylight.controller.cluster.access.concepts.RetiredGenerationException;
  52 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
  53 import org.opendaylight.controller.cluster.access.concepts.SliceableMessage;
  54 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  55 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
  56 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
  57 import org.opendaylight.controller.cluster.common.actor.Dispatchers;
  58 import org.opendaylight.controller.cluster.common.actor.Dispatchers.DispatcherType;
  59 import org.opendaylight.controller.cluster.common.actor.MessageTracker;
  60 import org.opendaylight.controller.cluster.common.actor.MessageTracker.Error;
  61 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
  62 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  63 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  64 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardDataTreeListenerInfoMXBeanImpl;
  65 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardMBeanFactory;
  66 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
  67 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
  68 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
  69 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  70 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransaction;
  71 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  72 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
  73 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  74 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  75 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
  76 import org.opendaylight.controller.cluster.datastore.messages.GetShardDataTree;
  77 import org.opendaylight.controller.cluster.datastore.messages.MakeLeaderLocal;
  78 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
  79 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
  80 import org.opendaylight.controller.cluster.datastore.messages.PersistAbortTransactionPayload;
  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.AbortTransactionPayload;
  86 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot;
  87 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot.ShardSnapshot;
  88 import org.opendaylight.controller.cluster.datastore.persisted.DisableTrackingPayload;
  89 import org.opendaylight.controller.cluster.datastore.persisted.PurgeTransactionPayload;
  90 import org.opendaylight.controller.cluster.messaging.MessageAssembler;
  91 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
  92 import org.opendaylight.controller.cluster.messaging.SliceOptions;
  93 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
  94 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
  95 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
  96 import org.opendaylight.controller.cluster.raft.LeadershipTransferFailedException;
  97 import org.opendaylight.controller.cluster.raft.RaftActor;
  98 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
  99 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
 100 import org.opendaylight.controller.cluster.raft.RaftState;
 101 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
 102 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
 103 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
 104 import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
 105 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
 106 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
 107 import org.opendaylight.yangtools.concepts.Identifier;
 108 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
 109 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
 110 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
 111 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
 112 import org.opendaylight.yangtools.yang.model.api.SchemaContextProvider;
 113 import scala.concurrent.duration.FiniteDuration;
 114
 115 /**
 116  * A Shard represents a portion of the logical data tree.
 117  *
 118  * <p>
 119  * Our Shard uses InMemoryDataTree as it's internal representation and delegates all requests it
 120  */
 121 public class Shard extends RaftActor {
 122
 123     @VisibleForTesting
 124     static final Object TX_COMMIT_TIMEOUT_CHECK_MESSAGE = new Object() {
 125         @Override
 126         public String toString() {
 127             return "txCommitTimeoutCheck";
 128         }
 129     };
 130
 131     @VisibleForTesting
 132     static final Object GET_SHARD_MBEAN_MESSAGE = new Object() {
 133         @Override
 134         public String toString() {
 135             return "getShardMBeanMessage";
 136         }
 137     };
 138
 139     static final Object RESUME_NEXT_PENDING_TRANSACTION = new Object() {
 140         @Override
 141         public String toString() {
 142             return "resumeNextPendingTransaction";
 143         }
 144     };
 145
 146     // FIXME: shard names should be encapsulated in their own class and this should be exposed as a constant.
 147     public static final String DEFAULT_NAME = "default";
 148
 149     private static final Collection<ABIVersion> SUPPORTED_ABIVERSIONS;
 150
 151     static {
 152         final ABIVersion[] values = ABIVersion.values();
 153         final ABIVersion[] real = Arrays.copyOfRange(values, 1, values.length - 1);
 154         SUPPORTED_ABIVERSIONS = ImmutableList.copyOf(real).reverse();
 155     }
 156
 157     // FIXME: make this a dynamic property based on mailbox size and maximum number of clients
 158     private static final int CLIENT_MAX_MESSAGES = 1000;
 159
 160     // The state of this Shard
 161     private final ShardDataTree store;
 162
 163     /// The name of this shard
 164     private final String name;
 165
 166     private final String shardName;
 167
 168     private final ShardStats shardMBean;
 169
 170     private final ShardDataTreeListenerInfoMXBeanImpl listenerInfoMXBean;
 171
 172     private DatastoreContext datastoreContext;
 173
 174     private final ShardCommitCoordinator commitCoordinator;
 175
 176     private long transactionCommitTimeout;
 177
 178     private Cancellable txCommitTimeoutCheckSchedule;
 179
 180     private final Optional<ActorRef> roleChangeNotifier;
 181
 182     private final MessageTracker appendEntriesReplyTracker;
 183
 184     private final ShardTransactionActorFactory transactionActorFactory;
 185
 186     private final ShardSnapshotCohort snapshotCohort;
 187
 188     private final DataTreeChangeListenerSupport treeChangeSupport = new DataTreeChangeListenerSupport(this);
 189
 190     private ShardSnapshot restoreFromSnapshot;
 191
 192     private final ShardTransactionMessageRetrySupport messageRetrySupport;
 193
 194     private final FrontendMetadata frontendMetadata;
 195     private Map<FrontendIdentifier, LeaderFrontendState> knownFrontends = ImmutableMap.of();
 196     private boolean paused;
 197
 198     private final MessageSlicer responseMessageSlicer;
 199     private final Dispatchers dispatchers;
 200
 201     private final MessageAssembler requestMessageAssembler;
 202
 203     protected Shard(final AbstractBuilder<?, ?> builder) {
 204         super(builder.getId().toString(), builder.getPeerAddresses(),
 205                 Optional.of(builder.getDatastoreContext().getShardRaftConfig()), DataStoreVersions.CURRENT_VERSION);
 206
 207         this.name = builder.getId().toString();
 208         this.shardName = builder.getId().getShardName();
 209         this.datastoreContext = builder.getDatastoreContext();
 210         this.restoreFromSnapshot = builder.getRestoreFromSnapshot();
 211         this.frontendMetadata = new FrontendMetadata(name);
 212
 213         setPersistence(datastoreContext.isPersistent());
 214
 215         LOG.info("Shard created : {}, persistent : {}", name, datastoreContext.isPersistent());
 216
 217         ShardDataTreeChangeListenerPublisherActorProxy treeChangeListenerPublisher =
 218                 new ShardDataTreeChangeListenerPublisherActorProxy(getContext(), name + "-DTCL-publisher", name);
 219         if (builder.getDataTree() != null) {
 220             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getDataTree(),
 221                     treeChangeListenerPublisher, name, frontendMetadata);
 222         } else {
 223             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getTreeType(),
 224                     builder.getDatastoreContext().getStoreRoot(), treeChangeListenerPublisher, name, frontendMetadata);
 225         }
 226
 227         shardMBean = ShardMBeanFactory.getShardStatsMBean(name, datastoreContext.getDataStoreMXBeanType(), this);
 228
 229         if (isMetricsCaptureEnabled()) {
 230             getContext().become(new MeteringBehavior(this));
 231         }
 232
 233         commitCoordinator = new ShardCommitCoordinator(store, LOG, this.name);
 234
 235         setTransactionCommitTimeout();
 236
 237         // create a notifier actor for each cluster member
 238         roleChangeNotifier = createRoleChangeNotifier(name);
 239
 240         appendEntriesReplyTracker = new MessageTracker(AppendEntriesReply.class,
 241                 getRaftActorContext().getConfigParams().getIsolatedCheckIntervalInMillis());
 242
 243         dispatchers = new Dispatchers(context().system().dispatchers());
 244         transactionActorFactory = new ShardTransactionActorFactory(store, datastoreContext,
 245             dispatchers.getDispatcherPath(Dispatchers.DispatcherType.Transaction),
 246                 self(), getContext(), shardMBean, builder.getId().getShardName());
 247
 248         snapshotCohort = ShardSnapshotCohort.create(getContext(), builder.getId().getMemberName(), store, LOG,
 249             this.name);
 250
 251         messageRetrySupport = new ShardTransactionMessageRetrySupport(this);
 252
 253         responseMessageSlicer = MessageSlicer.builder().logContext(this.name)
 254                 .messageSliceSize(datastoreContext.getMaximumMessageSliceSize())
 255                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 256                 .expireStateAfterInactivity(2, TimeUnit.MINUTES).build();
 257
 258         requestMessageAssembler = MessageAssembler.builder().logContext(this.name)
 259                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
 260                 .assembledMessageCallback((message, sender) -> self().tell(message, sender))
 261                 .expireStateAfterInactivity(datastoreContext.getRequestTimeout(), TimeUnit.NANOSECONDS).build();
 262
 263         listenerInfoMXBean = new ShardDataTreeListenerInfoMXBeanImpl(name, datastoreContext.getDataStoreMXBeanType(),
 264                 self());
 265         listenerInfoMXBean.register();
 266     }
 267
 268     private void setTransactionCommitTimeout() {
 269         transactionCommitTimeout = TimeUnit.MILLISECONDS.convert(
 270                 datastoreContext.getShardTransactionCommitTimeoutInSeconds(), TimeUnit.SECONDS) / 2;
 271     }
 272
 273     private Optional<ActorRef> createRoleChangeNotifier(final String shardId) {
 274         ActorRef shardRoleChangeNotifier = this.getContext().actorOf(
 275             RoleChangeNotifier.getProps(shardId), shardId + "-notifier");
 276         return Optional.of(shardRoleChangeNotifier);
 277     }
 278
 279     @Override
 280     public void postStop() {
 281         LOG.info("Stopping Shard {}", persistenceId());
 282
 283         super.postStop();
 284
 285         messageRetrySupport.close();
 286
 287         if (txCommitTimeoutCheckSchedule != null) {
 288             txCommitTimeoutCheckSchedule.cancel();
 289         }
 290
 291         commitCoordinator.abortPendingTransactions("Transaction aborted due to shutdown.", this);
 292
 293         shardMBean.unregisterMBean();
 294         listenerInfoMXBean.unregister();
 295     }
 296
 297     @Override
 298     protected void handleRecover(final Object message) {
 299         LOG.debug("{}: onReceiveRecover: Received message {} from {}", persistenceId(), message.getClass(),
 300             getSender());
 301
 302         super.handleRecover(message);
 303         if (LOG.isTraceEnabled()) {
 304             appendEntriesReplyTracker.begin();
 305         }
 306     }
 307
 308     @Override
 309     protected void handleNonRaftCommand(final Object message) {
 310         try (MessageTracker.Context context = appendEntriesReplyTracker.received(message)) {
 311             final Optional<Error> maybeError = context.error();
 312             if (maybeError.isPresent()) {
 313                 LOG.trace("{} : AppendEntriesReply failed to arrive at the expected interval {}", persistenceId(),
 314                     maybeError.get());
 315             }
 316
 317             store.resetTransactionBatch();
 318
 319             if (message instanceof RequestEnvelope) {
 320                 handleRequestEnvelope((RequestEnvelope)message);
 321             } else if (MessageAssembler.isHandledMessage(message)) {
 322                 handleRequestAssemblerMessage(message);
 323             } else if (message instanceof ConnectClientRequest) {
 324                 handleConnectClient((ConnectClientRequest)message);
 325             } else if (CreateTransaction.isSerializedType(message)) {
 326                 handleCreateTransaction(message);
 327             } else if (message instanceof BatchedModifications) {
 328                 handleBatchedModifications((BatchedModifications)message);
 329             } else if (message instanceof ForwardedReadyTransaction) {
 330                 handleForwardedReadyTransaction((ForwardedReadyTransaction) message);
 331             } else if (message instanceof ReadyLocalTransaction) {
 332                 handleReadyLocalTransaction((ReadyLocalTransaction)message);
 333             } else if (CanCommitTransaction.isSerializedType(message)) {
 334                 handleCanCommitTransaction(CanCommitTransaction.fromSerializable(message));
 335             } else if (CommitTransaction.isSerializedType(message)) {
 336                 handleCommitTransaction(CommitTransaction.fromSerializable(message));
 337             } else if (AbortTransaction.isSerializedType(message)) {
 338                 handleAbortTransaction(AbortTransaction.fromSerializable(message));
 339             } else if (CloseTransactionChain.isSerializedType(message)) {
 340                 closeTransactionChain(CloseTransactionChain.fromSerializable(message));
 341             } else if (message instanceof RegisterDataTreeChangeListener) {
 342                 treeChangeSupport.onMessage((RegisterDataTreeChangeListener) message, isLeader(), hasLeader());
 343             } else if (message instanceof UpdateSchemaContext) {
 344                 updateSchemaContext((UpdateSchemaContext) message);
 345             } else if (message instanceof PeerAddressResolved) {
 346                 PeerAddressResolved resolved = (PeerAddressResolved) message;
 347                 setPeerAddress(resolved.getPeerId(), resolved.getPeerAddress());
 348             } else if (TX_COMMIT_TIMEOUT_CHECK_MESSAGE.equals(message)) {
 349                 commitTimeoutCheck();
 350             } else if (message instanceof DatastoreContext) {
 351                 onDatastoreContext((DatastoreContext)message);
 352             } else if (message instanceof RegisterRoleChangeListener) {
 353                 roleChangeNotifier.get().forward(message, context());
 354             } else if (message instanceof FollowerInitialSyncUpStatus) {
 355                 shardMBean.setFollowerInitialSyncStatus(((FollowerInitialSyncUpStatus) message).isInitialSyncDone());
 356                 context().parent().tell(message, self());
 357             } else if (GET_SHARD_MBEAN_MESSAGE.equals(message)) {
 358                 sender().tell(getShardMBean(), self());
 359             } else if (message instanceof GetShardDataTree) {
 360                 sender().tell(store.getDataTree(), self());
 361             } else if (message instanceof ServerRemoved) {
 362                 context().parent().forward(message, context());
 363             } else if (ShardTransactionMessageRetrySupport.TIMER_MESSAGE_CLASS.isInstance(message)) {
 364                 messageRetrySupport.onTimerMessage(message);
 365             } else if (message instanceof DataTreeCohortActorRegistry.CohortRegistryCommand) {
 366                 store.processCohortRegistryCommand(getSender(),
 367                         (DataTreeCohortActorRegistry.CohortRegistryCommand) message);
 368             } else if (message instanceof PersistAbortTransactionPayload) {
 369                 final TransactionIdentifier txId = ((PersistAbortTransactionPayload) message).getTransactionId();
 370                 persistPayload(txId, AbortTransactionPayload.create(txId,
 371                     datastoreContext.getInitialPayloadSerializedBufferCapacity()), true);
 372                 persistPayload(txId, PurgeTransactionPayload.create(txId,
 373                     datastoreContext.getInitialPayloadSerializedBufferCapacity()), false);
 374             } else if (message instanceof MakeLeaderLocal) {
 375                 onMakeLeaderLocal();
 376             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
 377                 store.resumeNextPendingTransaction();
 378             } else if (!responseMessageSlicer.handleMessage(message)) {
 379                 super.handleNonRaftCommand(message);
 380             }
 381         }
 382     }
 383
 384     private void handleRequestAssemblerMessage(final Object message) {
 385         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
 386             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
 387             requestMessageAssembler.handleMessage(message, self());
 388         });
 389     }
 390
 391     @SuppressWarnings("checkstyle:IllegalCatch")
 392     private void handleRequestEnvelope(final RequestEnvelope envelope) {
 393         final long now = ticker().read();
 394         try {
 395             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
 396             if (success != null) {
 397                 final long executionTimeNanos = ticker().read() - now;
 398                 if (success instanceof SliceableMessage) {
 399                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
 400                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
 401                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
 402                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
 403                             .onFailureCallback(t -> LOG.warn("Error slicing response {}", success, t)).build()));
 404                 } else {
 405                     envelope.sendSuccess(success, executionTimeNanos);
 406                 }
 407             }
 408         } catch (RequestException e) {
 409             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
 410             envelope.sendFailure(e, ticker().read() - now);
 411         } catch (Exception e) {
 412             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
 413             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
 414                 ticker().read() - now);
 415         }
 416     }
 417
 418     private void commitTimeoutCheck() {
 419         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
 420         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
 421         requestMessageAssembler.checkExpiredAssembledMessageState();
 422     }
 423
 424     private Optional<Long> updateAccess(final SimpleShardDataTreeCohort cohort) {
 425         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
 426         final LeaderFrontendState state = knownFrontends.get(frontend);
 427         if (state == null) {
 428             // Not tell-based protocol, do nothing
 429             return Optional.absent();
 430         }
 431
 432         if (isIsolatedLeader()) {
 433             // We are isolated and no new request can come through until we emerge from it. We are still updating
 434             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
 435             return Optional.of(state.getLastSeenTicks());
 436         }
 437
 438         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
 439         return Optional.of(state.getLastConnectTicks());
 440     }
 441
 442     private void disableTracking(final DisableTrackingPayload payload) {
 443         final ClientIdentifier clientId = payload.getIdentifier();
 444         LOG.debug("{}: disabling tracking of {}", persistenceId(), clientId);
 445         frontendMetadata.disableTracking(clientId);
 446
 447         if (isLeader()) {
 448             final FrontendIdentifier frontendId = clientId.getFrontendId();
 449             final LeaderFrontendState frontend = knownFrontends.get(frontendId);
 450             if (frontend != null) {
 451                 if (clientId.equals(frontend.getIdentifier())) {
 452                     if (!(frontend instanceof LeaderFrontendState.Disabled)) {
 453                         verify(knownFrontends.replace(frontendId, frontend,
 454                             new LeaderFrontendState.Disabled(persistenceId(), clientId, store)));
 455                         LOG.debug("{}: leader state for {} disabled", persistenceId(), clientId);
 456                     } else {
 457                         LOG.debug("{}: leader state {} is already disabled", persistenceId(), frontend);
 458                     }
 459                 } else {
 460                     LOG.debug("{}: leader state {} does not match {}", persistenceId(), frontend, clientId);
 461                 }
 462             } else {
 463                 LOG.debug("{}: leader state for {} not found", persistenceId(), clientId);
 464             }
 465         }
 466     }
 467
 468     private void onMakeLeaderLocal() {
 469         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
 470         if (isLeader()) {
 471             getSender().tell(new Status.Success(null), getSelf());
 472             return;
 473         }
 474
 475         final ActorSelection leader = getLeader();
 476
 477         if (leader == null) {
 478             // Leader is not present. The cluster is most likely trying to
 479             // elect a leader and we should let that run its normal course
 480
 481             // TODO we can wait for the election to complete and retry the
 482             // request. We can also let the caller retry by sending a flag
 483             // in the response indicating the request is "reTryable".
 484             getSender().tell(new Failure(
 485                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
 486                             + "Currently there is no leader for " + persistenceId())),
 487                     getSelf());
 488             return;
 489         }
 490
 491         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
 492     }
 493
 494     // Acquire our frontend tracking handle and verify generation matches
 495     @Nullable
 496     private LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
 497         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
 498         if (existing != null) {
 499             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
 500             if (cmp == 0) {
 501                 existing.touch();
 502                 return existing;
 503             }
 504             if (cmp > 0) {
 505                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
 506                 throw new RetiredGenerationException(clientId.getGeneration(),
 507                     existing.getIdentifier().getGeneration());
 508             }
 509
 510             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
 511             existing.retire();
 512             knownFrontends.remove(clientId.getFrontendId());
 513         } else {
 514             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
 515         }
 516
 517         return null;
 518     }
 519
 520     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
 521         final LeaderFrontendState ret = findFrontend(clientId);
 522         if (ret != null) {
 523             return ret;
 524         }
 525
 526         // TODO: a dedicated exception would be better, but this is technically true, too
 527         throw new OutOfSequenceEnvelopeException(0);
 528     }
 529
 530     @Nonnull
 531     private static ABIVersion selectVersion(final ConnectClientRequest message) {
 532         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
 533         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
 534             if (clientRange.contains(v)) {
 535                 return v;
 536             }
 537         }
 538
 539         throw new IllegalArgumentException(String.format(
 540             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
 541             clientRange));
 542     }
 543
 544     @SuppressWarnings("checkstyle:IllegalCatch")
 545     private void handleConnectClient(final ConnectClientRequest message) {
 546         try {
 547             final ClientIdentifier clientId = message.getTarget();
 548             final LeaderFrontendState existing = findFrontend(clientId);
 549             if (existing != null) {
 550                 existing.touch();
 551             }
 552
 553             if (!isLeader() || !isLeaderActive()) {
 554                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 555                                 + "isLeadershipTransferInProgress: {}.",
 556                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
 557                 throw new NotLeaderException(getSelf());
 558             }
 559
 560             final ABIVersion selectedVersion = selectVersion(message);
 561             final LeaderFrontendState frontend;
 562             if (existing == null) {
 563                 frontend = new LeaderFrontendState.Enabled(persistenceId(), clientId, store);
 564                 knownFrontends.put(clientId.getFrontendId(), frontend);
 565                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
 566             } else {
 567                 frontend = existing;
 568             }
 569
 570             frontend.reconnect();
 571             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
 572                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
 573                 ActorRef.noSender());
 574         } catch (RequestException | RuntimeException e) {
 575             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
 576         }
 577     }
 578
 579     @Nullable
 580     private RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
 581             throws RequestException {
 582         // We are not the leader, hence we want to fail-fast.
 583         if (!isLeader() || paused || !isLeaderActive()) {
 584             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
 585                             + "isLeadershipTransferInProgress: {}, paused: {}",
 586                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
 587             throw new NotLeaderException(getSelf());
 588         }
 589
 590         final Request<?, ?> request = envelope.getMessage();
 591         if (request instanceof TransactionRequest) {
 592             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
 593             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
 594             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
 595         } else if (request instanceof LocalHistoryRequest) {
 596             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
 597             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
 598             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
 599         } else {
 600             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
 601             throw new UnsupportedRequestException(request);
 602         }
 603     }
 604
 605     private boolean hasLeader() {
 606         return getLeaderId() != null;
 607     }
 608
 609     public int getPendingTxCommitQueueSize() {
 610         return store.getQueueSize();
 611     }
 612
 613     public int getCohortCacheSize() {
 614         return commitCoordinator.getCohortCacheSize();
 615     }
 616
 617     @Override
 618     protected Optional<ActorRef> getRoleChangeNotifier() {
 619         return roleChangeNotifier;
 620     }
 621
 622     String getShardName() {
 623         return shardName;
 624     }
 625
 626     @Override
 627     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
 628             final short leaderPayloadVersion) {
 629         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 630                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 631     }
 632
 633     protected void onDatastoreContext(final DatastoreContext context) {
 634         datastoreContext = context;
 635
 636         setTransactionCommitTimeout();
 637
 638         setPersistence(datastoreContext.isPersistent());
 639
 640         updateConfigParams(datastoreContext.getShardRaftConfig());
 641     }
 642
 643     // applyState() will be invoked once consensus is reached on the payload
 644     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
 645         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
 646         if (canSkipPayload) {
 647             applyState(self(), id, payload);
 648         } else {
 649             // We are faking the sender
 650             persistData(self(), id, payload, batchHint);
 651         }
 652     }
 653
 654     private void handleCommitTransaction(final CommitTransaction commit) {
 655         final TransactionIdentifier txId = commit.getTransactionId();
 656         if (isLeader()) {
 657             askProtocolEncountered(txId);
 658             commitCoordinator.handleCommit(txId, getSender(), this);
 659         } else {
 660             ActorSelection leader = getLeader();
 661             if (leader == null) {
 662                 messageRetrySupport.addMessageToRetry(commit, getSender(), "Could not commit transaction " + txId);
 663             } else {
 664                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 665                 leader.forward(commit, getContext());
 666             }
 667         }
 668     }
 669
 670     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 671         final TransactionIdentifier txId = canCommit.getTransactionId();
 672         LOG.debug("{}: Can committing transaction {}", persistenceId(), txId);
 673
 674         if (isLeader()) {
 675             askProtocolEncountered(txId);
 676             commitCoordinator.handleCanCommit(txId, getSender(), this);
 677         } else {
 678             ActorSelection leader = getLeader();
 679             if (leader == null) {
 680                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 681                         "Could not canCommit transaction " + txId);
 682             } else {
 683                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 684                 leader.forward(canCommit, getContext());
 685             }
 686         }
 687     }
 688
 689     @SuppressWarnings("checkstyle:IllegalCatch")
 690     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
 691         askProtocolEncountered(batched.getTransactionId());
 692
 693         try {
 694             commitCoordinator.handleBatchedModifications(batched, sender, this);
 695         } catch (Exception e) {
 696             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 697                     batched.getTransactionId(), e);
 698             sender.tell(new Failure(e), getSelf());
 699         }
 700     }
 701
 702     private void handleBatchedModifications(final BatchedModifications batched) {
 703         // This message is sent to prepare the modifications transaction directly on the Shard as an
 704         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 705         // BatchedModifications message, the caller sets the ready flag in the message indicating
 706         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 707         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 708         // ReadyTransaction message.
 709
 710         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 711         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 712         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 713         // window where it could have a stale leader during leadership transitions.
 714         //
 715         boolean isLeaderActive = isLeaderActive();
 716         if (isLeader() && isLeaderActive) {
 717             handleBatchedModificationsLocal(batched, getSender());
 718         } else {
 719             ActorSelection leader = getLeader();
 720             if (!isLeaderActive || leader == null) {
 721                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 722                         "Could not process BatchedModifications " + batched.getTransactionId());
 723             } else {
 724                 // If this is not the first batch and leadership changed in between batched messages,
 725                 // we need to reconstruct previous BatchedModifications from the transaction
 726                 // DataTreeModification, honoring the max batched modification count, and forward all the
 727                 // previous BatchedModifications to the new leader.
 728                 Collection<BatchedModifications> newModifications = commitCoordinator
 729                         .createForwardedBatchedModifications(batched,
 730                                 datastoreContext.getShardBatchedModificationCount());
 731
 732                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 733                         newModifications.size(), leader);
 734
 735                 for (BatchedModifications bm : newModifications) {
 736                     leader.forward(bm, getContext());
 737                 }
 738             }
 739         }
 740     }
 741
 742     private boolean failIfIsolatedLeader(final ActorRef sender) {
 743         if (isIsolatedLeader()) {
 744             sender.tell(new Failure(new NoShardLeaderException(String.format(
 745                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
 746                     + " other follower nodes are down or this node is isolated by a network partition.",
 747                     persistenceId()))), getSelf());
 748             return true;
 749         }
 750
 751         return false;
 752     }
 753
 754     protected boolean isIsolatedLeader() {
 755         return getRaftState() == RaftState.IsolatedLeader;
 756     }
 757
 758     @SuppressWarnings("checkstyle:IllegalCatch")
 759     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 760         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
 761
 762         boolean isLeaderActive = isLeaderActive();
 763         if (isLeader() && isLeaderActive) {
 764             try {
 765                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
 766             } catch (Exception e) {
 767                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
 768                         message.getTransactionId(), e);
 769                 getSender().tell(new Failure(e), getSelf());
 770             }
 771         } else {
 772             ActorSelection leader = getLeader();
 773             if (!isLeaderActive || leader == null) {
 774                 messageRetrySupport.addMessageToRetry(message, getSender(),
 775                         "Could not process ready local transaction " + message.getTransactionId());
 776             } else {
 777                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 778                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 779                 leader.forward(message, getContext());
 780             }
 781         }
 782     }
 783
 784     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
 785         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
 786
 787         boolean isLeaderActive = isLeaderActive();
 788         if (isLeader() && isLeaderActive) {
 789             askProtocolEncountered(forwardedReady.getTransactionId());
 790             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
 791         } else {
 792             ActorSelection leader = getLeader();
 793             if (!isLeaderActive || leader == null) {
 794                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 795                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
 796             } else {
 797                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 798
 799                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
 800                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
 801                         forwardedReady.getParticipatingShardNames());
 802                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 803                 leader.forward(readyLocal, getContext());
 804             }
 805         }
 806     }
 807
 808     private void handleAbortTransaction(final AbortTransaction abort) {
 809         final TransactionIdentifier transactionId = abort.getTransactionId();
 810         askProtocolEncountered(transactionId);
 811         doAbortTransaction(transactionId, getSender());
 812     }
 813
 814     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
 815         commitCoordinator.handleAbort(transactionID, sender, this);
 816     }
 817
 818     private void handleCreateTransaction(final Object message) {
 819         if (isLeader()) {
 820             createTransaction(CreateTransaction.fromSerializable(message));
 821         } else if (getLeader() != null) {
 822             getLeader().forward(message, getContext());
 823         } else {
 824             getSender().tell(new Failure(new NoShardLeaderException(
 825                     "Could not create a shard transaction", persistenceId())), getSelf());
 826         }
 827     }
 828
 829     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 830         if (isLeader()) {
 831             final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
 832             askProtocolEncountered(id.getClientId());
 833
 834             // FIXME: CONTROLLER-1628: stage purge once no transactions are present
 835             store.closeTransactionChain(id, null);
 836             store.purgeTransactionChain(id, null);
 837         } else if (getLeader() != null) {
 838             getLeader().forward(closeTransactionChain, getContext());
 839         } else {
 840             LOG.warn("{}: Could not close transaction {}", persistenceId(), closeTransactionChain.getIdentifier());
 841         }
 842     }
 843
 844     @SuppressWarnings("checkstyle:IllegalCatch")
 845     private void createTransaction(final CreateTransaction createTransaction) {
 846         askProtocolEncountered(createTransaction.getTransactionId());
 847
 848         try {
 849             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
 850                     && failIfIsolatedLeader(getSender())) {
 851                 return;
 852             }
 853
 854             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 855                 createTransaction.getTransactionId());
 856
 857             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 858                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 859         } catch (Exception e) {
 860             getSender().tell(new Failure(e), getSelf());
 861         }
 862     }
 863
 864     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
 865         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 866         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 867             transactionId);
 868     }
 869
 870     // Called on leader only
 871     private void askProtocolEncountered(final TransactionIdentifier transactionId) {
 872         askProtocolEncountered(transactionId.getHistoryId().getClientId());
 873     }
 874
 875     // Called on leader only
 876     private void askProtocolEncountered(final ClientIdentifier clientId) {
 877         final LeaderFrontendState state = knownFrontends.get(clientId.getFrontendId());
 878         if (state instanceof LeaderFrontendState.Enabled) {
 879             LOG.debug("{}: encountered ask-based client {}, disabling transaction tracking", persistenceId(), clientId);
 880             persistPayload(clientId, DisableTrackingPayload.create(clientId,
 881                 datastoreContext.getInitialPayloadSerializedBufferCapacity()), false);
 882         }
 883     }
 884
 885     private void updateSchemaContext(final UpdateSchemaContext message) {
 886         updateSchemaContext(message.getSchemaContext());
 887     }
 888
 889     @VisibleForTesting
 890     void updateSchemaContext(final SchemaContext schemaContext) {
 891         store.updateSchemaContext(schemaContext);
 892     }
 893
 894     private boolean isMetricsCaptureEnabled() {
 895         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 896         return config.isMetricCaptureEnabled();
 897     }
 898
 899     @Override
 900     @VisibleForTesting
 901     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 902         return snapshotCohort;
 903     }
 904
 905     @Override
 906     @Nonnull
 907     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 908         if (restoreFromSnapshot == null) {
 909             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
 910         }
 911
 912         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
 913     }
 914
 915     @Override
 916     protected void onRecoveryComplete() {
 917         restoreFromSnapshot = null;
 918
 919         //notify shard manager
 920         getContext().parent().tell(new ActorInitialized(), getSelf());
 921
 922         // Being paranoid here - this method should only be called once but just in case...
 923         if (txCommitTimeoutCheckSchedule == null) {
 924             // Schedule a message to be periodically sent to check if the current in-progress
 925             // transaction should be expired and aborted.
 926             FiniteDuration period = FiniteDuration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 927             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 928                     period, period, getSelf(),
 929                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 930         }
 931     }
 932
 933     @Override
 934     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 935         if (data instanceof Payload) {
 936             if (data instanceof DisableTrackingPayload) {
 937                 disableTracking((DisableTrackingPayload) data);
 938                 return;
 939             }
 940
 941             try {
 942                 store.applyReplicatedPayload(identifier, (Payload)data);
 943             } catch (DataValidationFailedException | IOException e) {
 944                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 945             }
 946         } else {
 947             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
 948         }
 949     }
 950
 951     @Override
 952     protected void onStateChanged() {
 953         boolean isLeader = isLeader();
 954         boolean hasLeader = hasLeader();
 955         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
 956
 957         // If this actor is no longer the leader close all the transaction chains
 958         if (!isLeader) {
 959             if (LOG.isDebugEnabled()) {
 960                 LOG.debug(
 961                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
 962                     persistenceId(), getId());
 963             }
 964
 965             paused = false;
 966             store.purgeLeaderState();
 967         }
 968
 969         if (hasLeader && !isIsolatedLeader()) {
 970             messageRetrySupport.retryMessages();
 971         }
 972     }
 973
 974     @Override
 975     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
 976         shardMBean.incrementLeadershipChangeCount();
 977         paused = false;
 978
 979         if (!isLeader()) {
 980             if (!knownFrontends.isEmpty()) {
 981                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
 982                 knownFrontends = ImmutableMap.of();
 983             }
 984
 985             requestMessageAssembler.close();
 986
 987             if (!hasLeader()) {
 988                 // No leader anywhere, nothing else to do
 989                 return;
 990             }
 991
 992             // Another leader was elected. If we were the previous leader and had pending transactions, convert
 993             // them to transaction messages and send to the new leader.
 994             ActorSelection leader = getLeader();
 995             if (leader != null) {
 996                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
 997
 998                 if (!messagesToForward.isEmpty()) {
 999                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
1000                             messagesToForward.size(), leader);
1001
1002                     for (Object message : messagesToForward) {
1003                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
1004
1005                         leader.tell(message, self());
1006                     }
1007                 }
1008             } else {
1009                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
1010                         + "change and the leader address isn't available.", this);
1011             }
1012         } else {
1013             // We have become the leader, we need to reconstruct frontend state
1014             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
1015             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
1016         }
1017
1018         if (!isIsolatedLeader()) {
1019             messageRetrySupport.retryMessages();
1020         }
1021     }
1022
1023     /**
1024      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
1025      *
1026      * @return the converted messages
1027      */
1028     public Collection<?> convertPendingTransactionsToMessages() {
1029         return commitCoordinator.convertPendingTransactionsToMessages(
1030                 datastoreContext.getShardBatchedModificationCount());
1031     }
1032
1033     @Override
1034     protected void pauseLeader(final Runnable operation) {
1035         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
1036         paused = true;
1037
1038         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
1039         knownFrontends.values().forEach(LeaderFrontendState::retire);
1040         knownFrontends = ImmutableMap.of();
1041
1042         store.setRunOnPendingTransactionsComplete(operation);
1043     }
1044
1045     @Override
1046     protected void unpauseLeader() {
1047         LOG.debug("{}: In unpauseLeader", persistenceId());
1048         paused = false;
1049
1050         store.setRunOnPendingTransactionsComplete(null);
1051
1052         // Restore tell-based protocol state as if we were becoming the leader
1053         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
1054     }
1055
1056     @Override
1057     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
1058         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
1059                 .commitCohortActors(store.getCohortActors());
1060     }
1061
1062     @Override
1063     public String persistenceId() {
1064         return this.name;
1065     }
1066
1067     @VisibleForTesting
1068     ShardCommitCoordinator getCommitCoordinator() {
1069         return commitCoordinator;
1070     }
1071
1072     public DatastoreContext getDatastoreContext() {
1073         return datastoreContext;
1074     }
1075
1076     @VisibleForTesting
1077     public ShardDataTree getDataStore() {
1078         return store;
1079     }
1080
1081     @VisibleForTesting
1082     ShardStats getShardMBean() {
1083         return shardMBean;
1084     }
1085
1086     public static Builder builder() {
1087         return new Builder();
1088     }
1089
1090     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1091         private final Class<S> shardClass;
1092         private ShardIdentifier id;
1093         private Map<String, String> peerAddresses = Collections.emptyMap();
1094         private DatastoreContext datastoreContext;
1095         private SchemaContextProvider schemaContextProvider;
1096         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1097         private DataTree dataTree;
1098         private volatile boolean sealed;
1099
1100         protected AbstractBuilder(final Class<S> shardClass) {
1101             this.shardClass = shardClass;
1102         }
1103
1104         protected void checkSealed() {
1105             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1106         }
1107
1108         @SuppressWarnings("unchecked")
1109         private T self() {
1110             return (T) this;
1111         }
1112
1113         public T id(final ShardIdentifier newId) {
1114             checkSealed();
1115             this.id = newId;
1116             return self();
1117         }
1118
1119         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1120             checkSealed();
1121             this.peerAddresses = newPeerAddresses;
1122             return self();
1123         }
1124
1125         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1126             checkSealed();
1127             this.datastoreContext = newDatastoreContext;
1128             return self();
1129         }
1130
1131         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1132             checkSealed();
1133             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1134             return self();
1135         }
1136
1137         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1138             checkSealed();
1139             this.restoreFromSnapshot = newRestoreFromSnapshot;
1140             return self();
1141         }
1142
1143         public T dataTree(final DataTree newDataTree) {
1144             checkSealed();
1145             this.dataTree = newDataTree;
1146             return self();
1147         }
1148
1149         public ShardIdentifier getId() {
1150             return id;
1151         }
1152
1153         public Map<String, String> getPeerAddresses() {
1154             return peerAddresses;
1155         }
1156
1157         public DatastoreContext getDatastoreContext() {
1158             return datastoreContext;
1159         }
1160
1161         public SchemaContext getSchemaContext() {
1162             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1163         }
1164
1165         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1166             return restoreFromSnapshot;
1167         }
1168
1169         public DataTree getDataTree() {
1170             return dataTree;
1171         }
1172
1173         public TreeType getTreeType() {
1174             switch (datastoreContext.getLogicalStoreType()) {
1175                 case CONFIGURATION:
1176                     return TreeType.CONFIGURATION;
1177                 case OPERATIONAL:
1178                     return TreeType.OPERATIONAL;
1179                 default:
1180                     throw new IllegalStateException("Unhandled logical store type "
1181                             + datastoreContext.getLogicalStoreType());
1182             }
1183         }
1184
1185         protected void verify() {
1186             Preconditions.checkNotNull(id, "id should not be null");
1187             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1188             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1189             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1190         }
1191
1192         public Props props() {
1193             sealed = true;
1194             verify();
1195             return Props.create(shardClass, this);
1196         }
1197     }
1198
1199     public static class Builder extends AbstractBuilder<Builder, Shard> {
1200         Builder() {
1201             super(Shard.class);
1202         }
1203     }
1204
1205     Ticker ticker() {
1206         return Ticker.systemTicker();
1207     }
1208
1209     void scheduleNextPendingTransaction() {
1210         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1211     }
1212 }