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
   9 package org.opendaylight.controller.cluster.datastore;
  10
  11 import akka.actor.ActorRef;
  12 import akka.actor.ActorSelection;
  13 import akka.actor.Cancellable;
  14 import akka.actor.Props;
  15 import akka.serialization.Serialization;
  16 import com.google.common.annotations.VisibleForTesting;
  17 import com.google.common.base.Optional;
  18 import com.google.common.base.Preconditions;
  19 import java.io.IOException;
  20 import java.util.Collection;
  21 import java.util.Collections;
  22 import java.util.Map;
  23 import java.util.concurrent.ExecutionException;
  24 import java.util.concurrent.TimeUnit;
  25 import javax.annotation.Nonnull;
  26 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  27 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
  28 import org.opendaylight.controller.cluster.common.actor.MessageTracker;
  29 import org.opendaylight.controller.cluster.common.actor.MessageTracker.Error;
  30 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
  31 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  32 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  33 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardMBeanFactory;
  34 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
  35 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
  36 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
  37 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  38 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransaction;
  39 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
  40 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
  41 import org.opendaylight.controller.cluster.datastore.messages.CommitTransactionReply;
  42 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  43 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  44 import org.opendaylight.controller.cluster.datastore.messages.DatastoreSnapshot;
  45 import org.opendaylight.controller.cluster.datastore.messages.DatastoreSnapshot.ShardSnapshot;
  46 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
  47 import org.opendaylight.controller.cluster.datastore.messages.GetShardDataTree;
  48 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
  49 import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
  50 import org.opendaylight.controller.cluster.datastore.messages.RegisterChangeListener;
  51 import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
  52 import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
  53 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
  54 import org.opendaylight.controller.cluster.datastore.utils.Dispatchers;
  55 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
  56 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
  57 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
  58 import org.opendaylight.controller.cluster.raft.RaftActor;
  59 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
  60 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
  61 import org.opendaylight.controller.cluster.raft.RaftState;
  62 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
  63 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
  64 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
  65 import org.opendaylight.yangtools.concepts.Identifier;
  66 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
  67 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
  68 import org.opendaylight.yangtools.yang.data.api.schema.tree.ModificationType;
  69 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
  70 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  71 import scala.concurrent.duration.Duration;
  72 import scala.concurrent.duration.FiniteDuration;
  73
  74 /**
  75  * A Shard represents a portion of the logical data tree <br/>
  76  * <p>
  77  * Our Shard uses InMemoryDataTree as it's internal representation and delegates all requests it
  78  * </p>
  79  */
  80 public class Shard extends RaftActor {
  81
  82     @VisibleForTesting
  83     static final Object TX_COMMIT_TIMEOUT_CHECK_MESSAGE = new Object() {
  84         @Override
  85         public String toString() {
  86             return "txCommitTimeoutCheck";
  87         }
  88     };
  89
  90     @VisibleForTesting
  91     static final Object GET_SHARD_MBEAN_MESSAGE = new Object() {
  92         @Override
  93         public String toString() {
  94             return "getShardMBeanMessage";
  95         }
  96     };
  97
  98     // FIXME: shard names should be encapsulated in their own class and this should be exposed as a constant.
  99     public static final String DEFAULT_NAME = "default";
 100
 101     // The state of this Shard
 102     private final ShardDataTree store;
 103
 104     /// The name of this shard
 105     private final String name;
 106
 107     private final ShardStats shardMBean;
 108
 109     private DatastoreContext datastoreContext;
 110
 111     private final ShardCommitCoordinator commitCoordinator;
 112
 113     private long transactionCommitTimeout;
 114
 115     private Cancellable txCommitTimeoutCheckSchedule;
 116
 117     private final Optional<ActorRef> roleChangeNotifier;
 118
 119     private final MessageTracker appendEntriesReplyTracker;
 120
 121     private final ShardTransactionActorFactory transactionActorFactory;
 122
 123     private final ShardSnapshotCohort snapshotCohort;
 124
 125     private final DataTreeChangeListenerSupport treeChangeSupport = new DataTreeChangeListenerSupport(this);
 126     private final DataChangeListenerSupport changeSupport = new DataChangeListenerSupport(this);
 127
 128
 129     private ShardSnapshot restoreFromSnapshot;
 130
 131     private final ShardTransactionMessageRetrySupport messageRetrySupport;
 132
 133     protected Shard(AbstractBuilder<?, ?> builder) {
 134         super(builder.getId().toString(), builder.getPeerAddresses(),
 135                 Optional.of(builder.getDatastoreContext().getShardRaftConfig()), DataStoreVersions.CURRENT_VERSION);
 136
 137         this.name = builder.getId().toString();
 138         this.datastoreContext = builder.getDatastoreContext();
 139         this.restoreFromSnapshot = builder.getRestoreFromSnapshot();
 140
 141         setPersistence(datastoreContext.isPersistent());
 142
 143         LOG.info("Shard created : {}, persistent : {}", name, datastoreContext.isPersistent());
 144
 145         store = new ShardDataTree(builder.getSchemaContext(), builder.getTreeType(),
 146                 new ShardDataTreeChangeListenerPublisherActorProxy(getContext(), name + "-DTCL-publisher"),
 147                 new ShardDataChangeListenerPublisherActorProxy(getContext(), name + "-DCL-publisher"), name);
 148
 149         shardMBean = ShardMBeanFactory.getShardStatsMBean(name.toString(),
 150                 datastoreContext.getDataStoreMXBeanType());
 151         shardMBean.setShard(this);
 152
 153         if (isMetricsCaptureEnabled()) {
 154             getContext().become(new MeteringBehavior(this));
 155         }
 156
 157         commitCoordinator = new ShardCommitCoordinator(store,
 158                 datastoreContext.getShardCommitQueueExpiryTimeoutInMillis(),
 159                 datastoreContext.getShardTransactionCommitQueueCapacity(), LOG, this.name);
 160
 161         setTransactionCommitTimeout();
 162
 163         // create a notifier actor for each cluster member
 164         roleChangeNotifier = createRoleChangeNotifier(name.toString());
 165
 166         appendEntriesReplyTracker = new MessageTracker(AppendEntriesReply.class,
 167                 getRaftActorContext().getConfigParams().getIsolatedCheckIntervalInMillis());
 168
 169         transactionActorFactory = new ShardTransactionActorFactory(store, datastoreContext,
 170                 new Dispatchers(context().system().dispatchers()).getDispatcherPath(
 171                         Dispatchers.DispatcherType.Transaction), self(), getContext(), shardMBean);
 172
 173         snapshotCohort = new ShardSnapshotCohort(builder.getId().getMemberName(), transactionActorFactory, store,
 174             LOG, this.name);
 175
 176         messageRetrySupport = new ShardTransactionMessageRetrySupport(this);
 177     }
 178
 179     private void setTransactionCommitTimeout() {
 180         transactionCommitTimeout = TimeUnit.MILLISECONDS.convert(
 181                 datastoreContext.getShardTransactionCommitTimeoutInSeconds(), TimeUnit.SECONDS) / 2;
 182     }
 183
 184     private Optional<ActorRef> createRoleChangeNotifier(String shardId) {
 185         ActorRef shardRoleChangeNotifier = this.getContext().actorOf(
 186             RoleChangeNotifier.getProps(shardId), shardId + "-notifier");
 187         return Optional.of(shardRoleChangeNotifier);
 188     }
 189
 190     @Override
 191     public void postStop() {
 192         LOG.info("Stopping Shard {}", persistenceId());
 193
 194         super.postStop();
 195
 196         messageRetrySupport.close();
 197
 198         if(txCommitTimeoutCheckSchedule != null) {
 199             txCommitTimeoutCheckSchedule.cancel();
 200         }
 201
 202         commitCoordinator.abortPendingTransactions("Transaction aborted due to shutdown.", this);
 203
 204         shardMBean.unregisterMBean();
 205     }
 206
 207     @Override
 208     protected void handleRecover(final Object message) {
 209         LOG.debug("{}: onReceiveRecover: Received message {} from {}", persistenceId(), message.getClass(),
 210             getSender());
 211
 212         super.handleRecover(message);
 213         if (LOG.isTraceEnabled()) {
 214             appendEntriesReplyTracker.begin();
 215         }
 216     }
 217
 218     @Override
 219     protected void handleNonRaftCommand(final Object message) {
 220         try (final MessageTracker.Context context = appendEntriesReplyTracker.received(message)) {
 221             final Optional<Error> maybeError = context.error();
 222             if (maybeError.isPresent()) {
 223                 LOG.trace("{} : AppendEntriesReply failed to arrive at the expected interval {}", persistenceId(),
 224                     maybeError.get());
 225             }
 226
 227             if (CreateTransaction.isSerializedType(message)) {
 228                 handleCreateTransaction(message);
 229             } else if (message instanceof BatchedModifications) {
 230                 handleBatchedModifications((BatchedModifications)message);
 231             } else if (message instanceof ForwardedReadyTransaction) {
 232                 handleForwardedReadyTransaction((ForwardedReadyTransaction) message);
 233             } else if (message instanceof ReadyLocalTransaction) {
 234                 handleReadyLocalTransaction((ReadyLocalTransaction)message);
 235             } else if (CanCommitTransaction.isSerializedType(message)) {
 236                 handleCanCommitTransaction(CanCommitTransaction.fromSerializable(message));
 237             } else if (CommitTransaction.isSerializedType(message)) {
 238                 handleCommitTransaction(CommitTransaction.fromSerializable(message));
 239             } else if (AbortTransaction.isSerializedType(message)) {
 240                 handleAbortTransaction(AbortTransaction.fromSerializable(message));
 241             } else if (CloseTransactionChain.isSerializedType(message)) {
 242                 closeTransactionChain(CloseTransactionChain.fromSerializable(message));
 243             } else if (message instanceof RegisterChangeListener) {
 244                 changeSupport.onMessage((RegisterChangeListener) message, isLeader(), hasLeader());
 245             } else if (message instanceof RegisterDataTreeChangeListener) {
 246                 treeChangeSupport.onMessage((RegisterDataTreeChangeListener) message, isLeader(), hasLeader());
 247             } else if (message instanceof UpdateSchemaContext) {
 248                 updateSchemaContext((UpdateSchemaContext) message);
 249             } else if (message instanceof PeerAddressResolved) {
 250                 PeerAddressResolved resolved = (PeerAddressResolved) message;
 251                 setPeerAddress(resolved.getPeerId().toString(),
 252                         resolved.getPeerAddress());
 253             } else if (TX_COMMIT_TIMEOUT_CHECK_MESSAGE.equals(message)) {
 254                 commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
 255             } else if(message instanceof DatastoreContext) {
 256                 onDatastoreContext((DatastoreContext)message);
 257             } else if(message instanceof RegisterRoleChangeListener){
 258                 roleChangeNotifier.get().forward(message, context());
 259             } else if (message instanceof FollowerInitialSyncUpStatus) {
 260                 shardMBean.setFollowerInitialSyncStatus(((FollowerInitialSyncUpStatus) message).isInitialSyncDone());
 261                 context().parent().tell(message, self());
 262             } else if(GET_SHARD_MBEAN_MESSAGE.equals(message)){
 263                 sender().tell(getShardMBean(), self());
 264             } else if(message instanceof GetShardDataTree) {
 265                 sender().tell(store.getDataTree(), self());
 266             } else if(message instanceof ServerRemoved){
 267                 context().parent().forward(message, context());
 268             } else if(ShardTransactionMessageRetrySupport.TIMER_MESSAGE_CLASS.isInstance(message)) {
 269                 messageRetrySupport.onTimerMessage(message);
 270             } else if (message instanceof DataTreeCohortActorRegistry.CohortRegistryCommand) {
 271                 commitCoordinator.processCohortRegistryCommand(getSender(),
 272                         (DataTreeCohortActorRegistry.CohortRegistryCommand) message);
 273             } else {
 274                 super.handleNonRaftCommand(message);
 275             }
 276         }
 277     }
 278
 279     private boolean hasLeader() {
 280         return getLeaderId() != null;
 281     }
 282
 283     public int getPendingTxCommitQueueSize() {
 284         return commitCoordinator.getQueueSize();
 285     }
 286
 287     public int getCohortCacheSize() {
 288         return commitCoordinator.getCohortCacheSize();
 289     }
 290
 291     @Override
 292     protected Optional<ActorRef> getRoleChangeNotifier() {
 293         return roleChangeNotifier;
 294     }
 295
 296     @Override
 297     protected LeaderStateChanged newLeaderStateChanged(String memberId, String leaderId, short leaderPayloadVersion) {
 298         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
 299                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 300     }
 301
 302     protected void onDatastoreContext(DatastoreContext context) {
 303         datastoreContext = context;
 304
 305         commitCoordinator.setQueueCapacity(datastoreContext.getShardTransactionCommitQueueCapacity());
 306
 307         setTransactionCommitTimeout();
 308
 309         if(datastoreContext.isPersistent() && !persistence().isRecoveryApplicable()) {
 310             setPersistence(true);
 311         } else if(!datastoreContext.isPersistent() && persistence().isRecoveryApplicable()) {
 312             setPersistence(false);
 313         }
 314
 315         updateConfigParams(datastoreContext.getShardRaftConfig());
 316     }
 317
 318     private static boolean isEmptyCommit(final DataTreeCandidate candidate) {
 319         return ModificationType.UNMODIFIED.equals(candidate.getRootNode().getModificationType());
 320     }
 321
 322     void continueCommit(final CohortEntry cohortEntry) {
 323         final DataTreeCandidate candidate = cohortEntry.getCandidate();
 324
 325         // If we do not have any followers and we are not using persistence
 326         // or if cohortEntry has no modifications
 327         // we can apply modification to the state immediately
 328         if ((!hasFollowers() && !persistence().isRecoveryApplicable()) || isEmptyCommit(candidate)) {
 329             applyModificationToState(cohortEntry.getReplySender(), cohortEntry.getTransactionID(), candidate);
 330         } else {
 331             persistData(cohortEntry.getReplySender(), cohortEntry.getTransactionID(),
 332                     DataTreeCandidatePayload.create(candidate));
 333         }
 334     }
 335
 336     private void handleCommitTransaction(final CommitTransaction commit) {
 337         if (isLeader()) {
 338             if(!commitCoordinator.handleCommit(commit.getTransactionID(), getSender(), this)) {
 339                 shardMBean.incrementFailedTransactionsCount();
 340             }
 341         } else {
 342             ActorSelection leader = getLeader();
 343             if (leader == null) {
 344                 messageRetrySupport.addMessageToRetry(commit, getSender(),
 345                         "Could not commit transaction " + commit.getTransactionID());
 346             } else {
 347                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
 348                 leader.forward(commit, getContext());
 349             }
 350         }
 351     }
 352
 353     private void finishCommit(@Nonnull final ActorRef sender, @Nonnull final Identifier transactionID,
 354             @Nonnull final CohortEntry cohortEntry) {
 355         LOG.debug("{}: Finishing commit for transaction {}", persistenceId(), cohortEntry.getTransactionID());
 356
 357         try {
 358             try {
 359             cohortEntry.commit();
 360             } catch(ExecutionException e) {
 361                 // We may get a "store tree and candidate base differ" IllegalStateException from commit under
 362                 // certain edge case scenarios so we'll try to re-apply the candidate from scratch as a last
 363                 // resort. Eg, we're a follower and a tx payload is replicated but the leader goes down before
 364                 // applying it to the state. We then become the leader and a second tx is pre-committed and
 365                 // replicated. When consensus occurs, this will cause the first tx to be applied as a foreign
 366                 // candidate via applyState prior to the second tx. Since the second tx has already been
 367                 // pre-committed, when it gets here to commit it will get an IllegalStateException.
 368
 369                 // FIXME - this is not an ideal way to handle this scenario. This is temporary - a cleaner
 370                 // solution will be forthcoming.
 371                 if(e.getCause() instanceof IllegalStateException) {
 372                     LOG.debug("{}: commit failed for transaction {} - retrying as foreign candidate", persistenceId(),
 373                             transactionID, e);
 374                     store.applyForeignCandidate(transactionID, cohortEntry.getCandidate());
 375                 } else {
 376                     throw e;
 377                 }
 378             }
 379
 380             sender.tell(CommitTransactionReply.instance(cohortEntry.getClientVersion()).toSerializable(), getSelf());
 381
 382             shardMBean.incrementCommittedTransactionCount();
 383             shardMBean.setLastCommittedTransactionTime(System.currentTimeMillis());
 384
 385         } catch (Exception e) {
 386             sender.tell(new akka.actor.Status.Failure(e), getSelf());
 387
 388             LOG.error("{}, An exception occurred while committing transaction {}", persistenceId(),
 389                     transactionID, e);
 390             shardMBean.incrementFailedTransactionsCount();
 391         } finally {
 392             commitCoordinator.currentTransactionComplete(transactionID, true);
 393         }
 394     }
 395
 396     private void finishCommit(@Nonnull final ActorRef sender, final @Nonnull Identifier transactionID) {
 397         // With persistence enabled, this method is called via applyState by the leader strategy
 398         // after the commit has been replicated to a majority of the followers.
 399
 400         CohortEntry cohortEntry = commitCoordinator.getCohortEntryIfCurrent(transactionID);
 401         if (cohortEntry == null) {
 402             // The transaction is no longer the current commit. This can happen if the transaction
 403             // was aborted prior, most likely due to timeout in the front-end. We need to finish
 404             // committing the transaction though since it was successfully persisted and replicated
 405             // however we can't use the original cohort b/c it was already preCommitted and may
 406             // conflict with the current commit or may have been aborted so we commit with a new
 407             // transaction.
 408             cohortEntry = commitCoordinator.getAndRemoveCohortEntry(transactionID);
 409             if(cohortEntry != null) {
 410                 try {
 411                     store.applyForeignCandidate(transactionID, cohortEntry.getCandidate());
 412                 } catch (DataValidationFailedException e) {
 413                     shardMBean.incrementFailedTransactionsCount();
 414                     LOG.error("{}: Failed to re-apply transaction {}", persistenceId(), transactionID, e);
 415                 }
 416
 417                 sender.tell(CommitTransactionReply.instance(cohortEntry.getClientVersion()).toSerializable(),
 418                         getSelf());
 419             } else {
 420                 // This really shouldn't happen - it likely means that persistence or replication
 421                 // took so long to complete such that the cohort entry was expired from the cache.
 422                 IllegalStateException ex = new IllegalStateException(
 423                         String.format("%s: Could not finish committing transaction %s - no CohortEntry found",
 424                                 persistenceId(), transactionID));
 425                 LOG.error(ex.getMessage());
 426                 sender.tell(new akka.actor.Status.Failure(ex), getSelf());
 427             }
 428         } else {
 429             finishCommit(sender, transactionID, cohortEntry);
 430         }
 431     }
 432
 433     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
 434         LOG.debug("{}: Can committing transaction {}", persistenceId(), canCommit.getTransactionID());
 435
 436         if (isLeader()) {
 437         commitCoordinator.handleCanCommit(canCommit.getTransactionID(), getSender(), this);
 438         } else {
 439             ActorSelection leader = getLeader();
 440             if (leader == null) {
 441                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
 442                         "Could not canCommit transaction " + canCommit.getTransactionID());
 443             } else {
 444                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
 445                 leader.forward(canCommit, getContext());
 446             }
 447         }
 448     }
 449
 450     protected void handleBatchedModificationsLocal(BatchedModifications batched, ActorRef sender) {
 451         try {
 452             commitCoordinator.handleBatchedModifications(batched, sender, this, store.getSchemaContext());
 453         } catch (Exception e) {
 454             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
 455                     batched.getTransactionID(), e);
 456             sender.tell(new akka.actor.Status.Failure(e), getSelf());
 457         }
 458     }
 459
 460     private void handleBatchedModifications(BatchedModifications batched) {
 461         // This message is sent to prepare the modifications transaction directly on the Shard as an
 462         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
 463         // BatchedModifications message, the caller sets the ready flag in the message indicating
 464         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
 465         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
 466         // ReadyTransaction message.
 467
 468         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
 469         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
 470         // the primary/leader shard. However with timing and caching on the front-end, there's a small
 471         // window where it could have a stale leader during leadership transitions.
 472         //
 473         boolean isLeaderActive = isLeaderActive();
 474         if (isLeader() && isLeaderActive) {
 475             handleBatchedModificationsLocal(batched, getSender());
 476         } else {
 477             ActorSelection leader = getLeader();
 478             if (!isLeaderActive || leader == null) {
 479                 messageRetrySupport.addMessageToRetry(batched, getSender(),
 480                         "Could not commit transaction " + batched.getTransactionID());
 481             } else {
 482                 // If this is not the first batch and leadership changed in between batched messages,
 483                 // we need to reconstruct previous BatchedModifications from the transaction
 484                 // DataTreeModification, honoring the max batched modification count, and forward all the
 485                 // previous BatchedModifications to the new leader.
 486                 Collection<BatchedModifications> newModifications = commitCoordinator.createForwardedBatchedModifications(
 487                         batched, datastoreContext.getShardBatchedModificationCount());
 488
 489                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
 490                         newModifications.size(), leader);
 491
 492                 for(BatchedModifications bm: newModifications) {
 493                     leader.forward(bm, getContext());
 494                 }
 495             }
 496         }
 497     }
 498
 499     private boolean failIfIsolatedLeader(ActorRef sender) {
 500         if(isIsolatedLeader()) {
 501             sender.tell(new akka.actor.Status.Failure(new NoShardLeaderException(String.format(
 502                     "Shard %s was the leader but has lost contact with all of its followers. Either all" +
 503                     " other follower nodes are down or this node is isolated by a network partition.",
 504                     persistenceId()))), getSelf());
 505             return true;
 506         }
 507
 508         return false;
 509     }
 510
 511     protected boolean isIsolatedLeader() {
 512         return getRaftState() == RaftState.IsolatedLeader;
 513     }
 514
 515     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
 516         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionID());
 517
 518         boolean isLeaderActive = isLeaderActive();
 519         if (isLeader() && isLeaderActive) {
 520             try {
 521                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this, store.getSchemaContext());
 522             } catch (Exception e) {
 523                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
 524                         message.getTransactionID(), e);
 525                 getSender().tell(new akka.actor.Status.Failure(e), getSelf());
 526             }
 527         } else {
 528             ActorSelection leader = getLeader();
 529             if (!isLeaderActive || leader == null) {
 530                 messageRetrySupport.addMessageToRetry(message, getSender(),
 531                         "Could not commit transaction " + message.getTransactionID());
 532             } else {
 533                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
 534                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 535                 leader.forward(message, getContext());
 536             }
 537         }
 538     }
 539
 540     private void handleForwardedReadyTransaction(ForwardedReadyTransaction forwardedReady) {
 541         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionID());
 542
 543         boolean isLeaderActive = isLeaderActive();
 544         if (isLeader() && isLeaderActive) {
 545             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this,
 546                     store.getSchemaContext());
 547         } else {
 548             ActorSelection leader = getLeader();
 549             if (!isLeaderActive || leader == null) {
 550                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
 551                         "Could not commit transaction " + forwardedReady.getTransactionID());
 552             } else {
 553                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
 554
 555                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionID(),
 556                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit());
 557                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
 558                 leader.forward(readyLocal, getContext());
 559             }
 560         }
 561     }
 562
 563     private void handleAbortTransaction(final AbortTransaction abort) {
 564         doAbortTransaction(abort.getTransactionID(), getSender());
 565     }
 566
 567     void doAbortTransaction(final TransactionIdentifier transactionID, final ActorRef sender) {
 568         commitCoordinator.handleAbort(transactionID, sender, this);
 569     }
 570
 571     private void handleCreateTransaction(final Object message) {
 572         if (isLeader()) {
 573             createTransaction(CreateTransaction.fromSerializable(message));
 574         } else if (getLeader() != null) {
 575             getLeader().forward(message, getContext());
 576         } else {
 577             getSender().tell(new akka.actor.Status.Failure(new NoShardLeaderException(
 578                     "Could not create a shard transaction", persistenceId())), getSelf());
 579         }
 580     }
 581
 582     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
 583         store.closeTransactionChain(closeTransactionChain.getTransactionChainId());
 584     }
 585
 586     private void createTransaction(CreateTransaction createTransaction) {
 587         try {
 588             if(TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY &&
 589                     failIfIsolatedLeader(getSender())) {
 590                 return;
 591             }
 592
 593             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
 594                 createTransaction.getTransactionId());
 595
 596             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
 597                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
 598         } catch (Exception e) {
 599             getSender().tell(new akka.actor.Status.Failure(e), getSelf());
 600         }
 601     }
 602
 603     private ActorRef createTransaction(int transactionType, TransactionIdentifier transactionId) {
 604         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
 605         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
 606             transactionId);
 607     }
 608
 609     private void commitWithNewTransaction(final BatchedModifications modification) {
 610         ReadWriteShardDataTreeTransaction tx = store.newReadWriteTransaction(modification.getTransactionID());
 611         modification.apply(tx.getSnapshot());
 612         try {
 613             snapshotCohort.syncCommitTransaction(tx);
 614             shardMBean.incrementCommittedTransactionCount();
 615             shardMBean.setLastCommittedTransactionTime(System.currentTimeMillis());
 616         } catch (Exception e) {
 617             shardMBean.incrementFailedTransactionsCount();
 618             LOG.error("{}: Failed to commit", persistenceId(), e);
 619         }
 620     }
 621
 622     private void updateSchemaContext(final UpdateSchemaContext message) {
 623         updateSchemaContext(message.getSchemaContext());
 624     }
 625
 626     @VisibleForTesting
 627     void updateSchemaContext(final SchemaContext schemaContext) {
 628         store.updateSchemaContext(schemaContext);
 629     }
 630
 631     private boolean isMetricsCaptureEnabled() {
 632         CommonConfig config = new CommonConfig(getContext().system().settings().config());
 633         return config.isMetricCaptureEnabled();
 634     }
 635
 636     @Override
 637     @VisibleForTesting
 638     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
 639         return snapshotCohort;
 640     }
 641
 642     @Override
 643     @Nonnull
 644     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
 645         return new ShardRecoveryCoordinator(store, store.getSchemaContext(),
 646                 restoreFromSnapshot != null ? restoreFromSnapshot.getSnapshot() : null, persistenceId(), LOG);
 647     }
 648
 649     @Override
 650     protected void onRecoveryComplete() {
 651         restoreFromSnapshot = null;
 652
 653         //notify shard manager
 654         getContext().parent().tell(new ActorInitialized(), getSelf());
 655
 656         // Being paranoid here - this method should only be called once but just in case...
 657         if(txCommitTimeoutCheckSchedule == null) {
 658             // Schedule a message to be periodically sent to check if the current in-progress
 659             // transaction should be expired and aborted.
 660             FiniteDuration period = Duration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
 661             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
 662                     period, period, getSelf(),
 663                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
 664         }
 665     }
 666
 667     @Override
 668     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
 669         if (data instanceof DataTreeCandidatePayload) {
 670             if (clientActor == null) {
 671                 // No clientActor indicates a replica coming from the leader
 672                 try {
 673                     store.applyForeignCandidate(identifier, ((DataTreeCandidatePayload)data).getCandidate());
 674                 } catch (DataValidationFailedException | IOException e) {
 675                     LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
 676                 }
 677             } else {
 678                 // Replication consensus reached, proceed to commit
 679                 finishCommit(clientActor, identifier);
 680             }
 681         } else {
 682             LOG.error("{}: Unknown state received {} ClassLoader {}", persistenceId(), data,
 683                 data.getClass().getClassLoader());
 684         }
 685     }
 686
 687     private void applyModificationToState(ActorRef clientActor, Identifier identifier, Object modification) {
 688         if(modification == null) {
 689             LOG.error(
 690                     "{}: modification is null - this is very unexpected, clientActor = {}, identifier = {}",
 691                     persistenceId(), identifier, clientActor != null ? clientActor.path().toString() : null);
 692         } else if(clientActor == null) {
 693             // There's no clientActor to which to send a commit reply so we must be applying
 694             // replicated state from the leader.
 695
 696             // The only implementation we know of is BatchedModifications, which also carries a transaction
 697             // identifier -- which we really need that.
 698             Preconditions.checkArgument(modification instanceof BatchedModifications);
 699             commitWithNewTransaction((BatchedModifications)modification);
 700         } else {
 701             // This must be the OK to commit after replication consensus.
 702             finishCommit(clientActor, identifier);
 703         }
 704     }
 705
 706     @Override
 707     protected void onStateChanged() {
 708         boolean isLeader = isLeader();
 709         boolean hasLeader = hasLeader();
 710         changeSupport.onLeadershipChange(isLeader, hasLeader);
 711         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
 712
 713         // If this actor is no longer the leader close all the transaction chains
 714         if (!isLeader) {
 715             if(LOG.isDebugEnabled()) {
 716                 LOG.debug(
 717                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
 718                     persistenceId(), getId());
 719             }
 720
 721             store.closeAllTransactionChains();
 722         }
 723
 724         if(hasLeader && !isIsolatedLeader()) {
 725             messageRetrySupport.retryMessages();
 726         }
 727     }
 728
 729     @Override
 730     protected void onLeaderChanged(String oldLeader, String newLeader) {
 731         shardMBean.incrementLeadershipChangeCount();
 732
 733         boolean hasLeader = hasLeader();
 734         if(hasLeader && !isLeader()) {
 735             // Another leader was elected. If we were the previous leader and had pending transactions, convert
 736             // them to transaction messages and send to the new leader.
 737             ActorSelection leader = getLeader();
 738             if(leader != null) {
 739                 Collection<Object> messagesToForward = commitCoordinator.convertPendingTransactionsToMessages(
 740                         datastoreContext.getShardBatchedModificationCount());
 741
 742                 if(!messagesToForward.isEmpty()) {
 743                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
 744                             messagesToForward.size(), leader);
 745
 746                     for(Object message: messagesToForward) {
 747                         leader.tell(message, self());
 748                     }
 749                 }
 750             } else {
 751                 commitCoordinator.abortPendingTransactions(
 752                         "The transacton was aborted due to inflight leadership change and the leader address isn't available.",
 753                         this);
 754             }
 755         }
 756
 757         if(hasLeader && !isIsolatedLeader()) {
 758             messageRetrySupport.retryMessages();
 759         }
 760     }
 761
 762     @Override
 763     protected void pauseLeader(Runnable operation) {
 764         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
 765         commitCoordinator.setRunOnPendingTransactionsComplete(operation);
 766     }
 767
 768     @Override
 769     public String persistenceId() {
 770         return this.name;
 771     }
 772
 773     @VisibleForTesting
 774     ShardCommitCoordinator getCommitCoordinator() {
 775         return commitCoordinator;
 776     }
 777
 778     public DatastoreContext getDatastoreContext() {
 779         return datastoreContext;
 780     }
 781
 782     @VisibleForTesting
 783     public ShardDataTree getDataStore() {
 784         return store;
 785     }
 786
 787     @VisibleForTesting
 788     ShardStats getShardMBean() {
 789         return shardMBean;
 790     }
 791
 792     public static Builder builder() {
 793         return new Builder();
 794     }
 795
 796     public static abstract class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
 797         private final Class<S> shardClass;
 798         private ShardIdentifier id;
 799         private Map<String, String> peerAddresses = Collections.emptyMap();
 800         private DatastoreContext datastoreContext;
 801         private SchemaContext schemaContext;
 802         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
 803         private volatile boolean sealed;
 804
 805         protected AbstractBuilder(Class<S> shardClass) {
 806             this.shardClass = shardClass;
 807         }
 808
 809         protected void checkSealed() {
 810             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
 811         }
 812
 813         @SuppressWarnings("unchecked")
 814         private T self() {
 815             return (T) this;
 816         }
 817
 818         public T id(ShardIdentifier id) {
 819             checkSealed();
 820             this.id = id;
 821             return self();
 822         }
 823
 824         public T peerAddresses(Map<String, String> peerAddresses) {
 825             checkSealed();
 826             this.peerAddresses = peerAddresses;
 827             return self();
 828         }
 829
 830         public T datastoreContext(DatastoreContext datastoreContext) {
 831             checkSealed();
 832             this.datastoreContext = datastoreContext;
 833             return self();
 834         }
 835
 836         public T schemaContext(SchemaContext schemaContext) {
 837             checkSealed();
 838             this.schemaContext = schemaContext;
 839             return self();
 840         }
 841
 842         public T restoreFromSnapshot(DatastoreSnapshot.ShardSnapshot restoreFromSnapshot) {
 843             checkSealed();
 844             this.restoreFromSnapshot = restoreFromSnapshot;
 845             return self();
 846         }
 847
 848         public ShardIdentifier getId() {
 849             return id;
 850         }
 851
 852         public Map<String, String> getPeerAddresses() {
 853             return peerAddresses;
 854         }
 855
 856         public DatastoreContext getDatastoreContext() {
 857             return datastoreContext;
 858         }
 859
 860         public SchemaContext getSchemaContext() {
 861             return schemaContext;
 862         }
 863
 864         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
 865             return restoreFromSnapshot;
 866         }
 867
 868         public TreeType getTreeType() {
 869             switch (datastoreContext.getLogicalStoreType()) {
 870             case CONFIGURATION:
 871                 return TreeType.CONFIGURATION;
 872             case OPERATIONAL:
 873                 return TreeType.OPERATIONAL;
 874             }
 875
 876             throw new IllegalStateException("Unhandled logical store type " + datastoreContext.getLogicalStoreType());
 877         }
 878
 879         protected void verify() {
 880             Preconditions.checkNotNull(id, "id should not be null");
 881             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
 882             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
 883             Preconditions.checkNotNull(schemaContext, "schemaContext should not be null");
 884         }
 885
 886         public Props props() {
 887             sealed = true;
 888             verify();
 889             return Props.create(shardClass, this);
 890         }
 891     }
 892
 893     public static class Builder extends AbstractBuilder<Builder, Shard> {
 894         private Builder() {
 895             super(Shard.class);
 896         }
 897     }
 898 }