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

   1 /*
   2  * Copyright (c) 2015 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 akka.actor.ActorRef;
  11 import akka.util.Timeout;
  12 import com.google.common.annotations.VisibleForTesting;
  13 import com.google.common.base.Optional;
  14 import com.google.common.base.Preconditions;
  15 import com.google.common.base.Stopwatch;
  16 import com.google.common.base.Verify;
  17 import com.google.common.collect.ImmutableList;
  18 import com.google.common.collect.ImmutableMap;
  19 import com.google.common.collect.ImmutableMap.Builder;
  20 import com.google.common.primitives.UnsignedLong;
  21 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  22 import java.io.File;
  23 import java.io.IOException;
  24 import java.util.AbstractMap.SimpleEntry;
  25 import java.util.ArrayDeque;
  26 import java.util.ArrayList;
  27 import java.util.Collection;
  28 import java.util.HashMap;
  29 import java.util.Iterator;
  30 import java.util.Map;
  31 import java.util.Map.Entry;
  32 import java.util.Queue;
  33 import java.util.concurrent.ExecutionException;
  34 import java.util.concurrent.TimeUnit;
  35 import java.util.concurrent.TimeoutException;
  36 import java.util.function.UnaryOperator;
  37 import javax.annotation.Nonnull;
  38 import javax.annotation.concurrent.NotThreadSafe;
  39 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
  40 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  41 import org.opendaylight.controller.cluster.datastore.DataTreeCohortActorRegistry.CohortRegistryCommand;
  42 import org.opendaylight.controller.cluster.datastore.ShardDataTreeCohort.State;
  43 import org.opendaylight.controller.cluster.datastore.persisted.CommitTransactionPayload;
  44 import org.opendaylight.controller.cluster.datastore.persisted.MetadataShardDataTreeSnapshot;
  45 import org.opendaylight.controller.cluster.datastore.persisted.ShardDataTreeSnapshot;
  46 import org.opendaylight.controller.cluster.datastore.persisted.ShardDataTreeSnapshotMetadata;
  47 import org.opendaylight.controller.cluster.datastore.utils.DataTreeModificationOutput;
  48 import org.opendaylight.controller.cluster.datastore.utils.PruningDataTreeModification;
  49 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
  50 import org.opendaylight.controller.md.sal.common.api.data.AsyncDataBroker.DataChangeScope;
  51 import org.opendaylight.controller.md.sal.common.api.data.AsyncDataChangeListener;
  52 import org.opendaylight.controller.md.sal.common.api.data.OptimisticLockFailedException;
  53 import org.opendaylight.controller.md.sal.common.api.data.TransactionCommitFailedException;
  54 import org.opendaylight.controller.md.sal.dom.api.DOMDataTreeChangeListener;
  55 import org.opendaylight.controller.md.sal.dom.store.impl.DataChangeListenerRegistration;
  56 import org.opendaylight.yangtools.concepts.Identifier;
  57 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  58 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  59 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  60 import org.opendaylight.yangtools.yang.data.api.schema.tree.ConflictingModificationAppliedException;
  61 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
  62 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateTip;
  63 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidates;
  64 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
  65 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeSnapshot;
  66 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
  67 import org.opendaylight.yangtools.yang.data.api.schema.tree.ModificationType;
  68 import org.opendaylight.yangtools.yang.data.api.schema.tree.TipProducingDataTree;
  69 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
  70 import org.opendaylight.yangtools.yang.data.impl.schema.tree.InMemoryDataTreeFactory;
  71 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  72 import org.slf4j.Logger;
  73 import org.slf4j.LoggerFactory;
  74 import scala.concurrent.duration.Duration;
  75
  76 /**
  77  * Internal shard state, similar to a DOMStore, but optimized for use in the actor system,
  78  * e.g. it does not expose public interfaces and assumes it is only ever called from a
  79  * single thread.
  80  * <p/>
  81  * This class is not part of the API contract and is subject to change at any time.
  82  */
  83 @NotThreadSafe
  84 public class ShardDataTree extends ShardDataTreeTransactionParent {
  85     private static final class CommitEntry {
  86         final SimpleShardDataTreeCohort cohort;
  87         long lastAccess;
  88
  89         CommitEntry(final SimpleShardDataTreeCohort cohort, final long now) {
  90             this.cohort = Preconditions.checkNotNull(cohort);
  91             lastAccess = now;
  92         }
  93     }
  94
  95     private static final Timeout COMMIT_STEP_TIMEOUT = new Timeout(Duration.create(5, TimeUnit.SECONDS));
  96     private static final Logger LOG = LoggerFactory.getLogger(ShardDataTree.class);
  97
  98     private final Map<LocalHistoryIdentifier, ShardDataTreeTransactionChain> transactionChains = new HashMap<>();
  99     private final DataTreeCohortActorRegistry cohortRegistry = new DataTreeCohortActorRegistry();
 100     private final Queue<CommitEntry> pendingTransactions = new ArrayDeque<>();
 101     private final ShardDataTreeChangeListenerPublisher treeChangeListenerPublisher;
 102     private final ShardDataChangeListenerPublisher dataChangeListenerPublisher;
 103     private final Collection<ShardDataTreeMetadata<?>> metadata;
 104     private final TipProducingDataTree dataTree;
 105     private final String logContext;
 106     private final Shard shard;
 107     private Runnable runOnPendingTransactionsComplete;
 108
 109     private SchemaContext schemaContext;
 110
 111     public ShardDataTree(final Shard shard, final SchemaContext schemaContext, final TipProducingDataTree dataTree,
 112             final ShardDataTreeChangeListenerPublisher treeChangeListenerPublisher,
 113             final ShardDataChangeListenerPublisher dataChangeListenerPublisher, final String logContext,
 114             final ShardDataTreeMetadata<?>... metadata) {
 115         this.dataTree = Preconditions.checkNotNull(dataTree);
 116         updateSchemaContext(schemaContext);
 117
 118         this.shard = Preconditions.checkNotNull(shard);
 119         this.treeChangeListenerPublisher = Preconditions.checkNotNull(treeChangeListenerPublisher);
 120         this.dataChangeListenerPublisher = Preconditions.checkNotNull(dataChangeListenerPublisher);
 121         this.logContext = Preconditions.checkNotNull(logContext);
 122         this.metadata = ImmutableList.copyOf(metadata);
 123     }
 124
 125     public ShardDataTree(final Shard shard, final SchemaContext schemaContext, final TreeType treeType,
 126             final ShardDataTreeChangeListenerPublisher treeChangeListenerPublisher,
 127             final ShardDataChangeListenerPublisher dataChangeListenerPublisher, final String logContext) {
 128         this(shard, schemaContext, InMemoryDataTreeFactory.getInstance().create(treeType),
 129                 treeChangeListenerPublisher, dataChangeListenerPublisher, logContext);
 130     }
 131
 132     @VisibleForTesting
 133     public ShardDataTree(final Shard shard, final SchemaContext schemaContext, final TreeType treeType) {
 134         this(shard, schemaContext, treeType, new DefaultShardDataTreeChangeListenerPublisher(),
 135                 new DefaultShardDataChangeListenerPublisher(), "");
 136     }
 137
 138     String logContext() {
 139         return logContext;
 140     }
 141
 142     public TipProducingDataTree getDataTree() {
 143         return dataTree;
 144     }
 145
 146     SchemaContext getSchemaContext() {
 147         return schemaContext;
 148     }
 149
 150     void updateSchemaContext(final SchemaContext newSchemaContext) {
 151         dataTree.setSchemaContext(newSchemaContext);
 152         this.schemaContext = Preconditions.checkNotNull(newSchemaContext);
 153     }
 154
 155     /**
 156      * Take a snapshot of current state for later recovery.
 157      *
 158      * @return A state snapshot
 159      */
 160     @Nonnull ShardDataTreeSnapshot takeStateSnapshot() {
 161         final NormalizedNode<?, ?> rootNode = dataTree.takeSnapshot().readNode(YangInstanceIdentifier.EMPTY).get();
 162         final Builder<Class<? extends ShardDataTreeSnapshotMetadata<?>>, ShardDataTreeSnapshotMetadata<?>> metaBuilder =
 163                 ImmutableMap.builder();
 164
 165         for (ShardDataTreeMetadata<?> m : metadata) {
 166             final ShardDataTreeSnapshotMetadata<?> meta = m.toSnapshot();
 167             if (meta != null) {
 168                 metaBuilder.put(meta.getType(), meta);
 169             }
 170         }
 171
 172         return new MetadataShardDataTreeSnapshot(rootNode, metaBuilder.build());
 173     }
 174
 175     private void applySnapshot(@Nonnull final ShardDataTreeSnapshot snapshot,
 176             final UnaryOperator<DataTreeModification> wrapper) throws DataValidationFailedException {
 177         final Stopwatch elapsed = Stopwatch.createStarted();
 178
 179         if (!pendingTransactions.isEmpty()) {
 180             LOG.warn("{}: applying state snapshot with pending transactions", logContext);
 181         }
 182
 183         final Map<Class<? extends ShardDataTreeSnapshotMetadata<?>>, ShardDataTreeSnapshotMetadata<?>> snapshotMeta;
 184         if (snapshot instanceof MetadataShardDataTreeSnapshot) {
 185             snapshotMeta = ((MetadataShardDataTreeSnapshot) snapshot).getMetadata();
 186         } else {
 187             snapshotMeta = ImmutableMap.of();
 188         }
 189
 190         for (ShardDataTreeMetadata<?> m : metadata) {
 191             final ShardDataTreeSnapshotMetadata<?> s = snapshotMeta.get(m.getSupportedType());
 192             if (s != null) {
 193                 m.applySnapshot(s);
 194             } else {
 195                 m.reset();
 196             }
 197         }
 198
 199         final DataTreeModification mod = wrapper.apply(dataTree.takeSnapshot().newModification());
 200         // delete everything first
 201         mod.delete(YangInstanceIdentifier.EMPTY);
 202
 203         final java.util.Optional<NormalizedNode<?, ?>> maybeNode = snapshot.getRootNode();
 204         if (maybeNode.isPresent()) {
 205             // Add everything from the remote node back
 206             mod.write(YangInstanceIdentifier.EMPTY, maybeNode.get());
 207         }
 208         mod.ready();
 209
 210         final DataTreeModification unwrapped = unwrap(mod);
 211         dataTree.validate(unwrapped);
 212         DataTreeCandidateTip candidate = dataTree.prepare(unwrapped);
 213         dataTree.commit(candidate);
 214         notifyListeners(candidate);
 215
 216         LOG.debug("{}: state snapshot applied in %s", logContext, elapsed);
 217     }
 218
 219     /**
 220      * Apply a snapshot coming from the leader. This method assumes the leader and follower SchemaContexts match and
 221      * does not perform any pruning.
 222      *
 223      * @param snapshot Snapshot that needs to be applied
 224      * @throws DataValidationFailedException when the snapshot fails to apply
 225      */
 226     void applySnapshot(@Nonnull final ShardDataTreeSnapshot snapshot) throws DataValidationFailedException {
 227         applySnapshot(snapshot, UnaryOperator.identity());
 228     }
 229
 230     private PruningDataTreeModification wrapWithPruning(final DataTreeModification delegate) {
 231         return new PruningDataTreeModification(delegate, dataTree, schemaContext);
 232     }
 233
 234     private static DataTreeModification unwrap(final DataTreeModification modification) {
 235         if (modification instanceof PruningDataTreeModification) {
 236             return ((PruningDataTreeModification)modification).delegate();
 237         }
 238         return modification;
 239     }
 240
 241     /**
 242      * Apply a snapshot coming from recovery. This method does not assume the SchemaContexts match and performs data
 243      * pruning in an attempt to adjust the state to our current SchemaContext.
 244      *
 245      * @param snapshot Snapshot that needs to be applied
 246      * @throws DataValidationFailedException when the snapshot fails to apply
 247      */
 248     void applyRecoverySnapshot(final @Nonnull ShardDataTreeSnapshot snapshot) throws DataValidationFailedException {
 249         applySnapshot(snapshot, this::wrapWithPruning);
 250     }
 251
 252     @SuppressWarnings("checkstyle:IllegalCatch")
 253     private void applyRecoveryCandidate(final DataTreeCandidate candidate) throws DataValidationFailedException {
 254         final PruningDataTreeModification mod = wrapWithPruning(dataTree.takeSnapshot().newModification());
 255         DataTreeCandidates.applyToModification(mod, candidate);
 256         mod.ready();
 257
 258         final DataTreeModification unwrapped = mod.delegate();
 259         LOG.trace("{}: Applying recovery modification {}", logContext, unwrapped);
 260
 261         try {
 262             dataTree.validate(unwrapped);
 263             dataTree.commit(dataTree.prepare(unwrapped));
 264         } catch (Exception e) {
 265             File file = new File(System.getProperty("karaf.data", "."),
 266                     "failed-recovery-payload-" + logContext + ".out");
 267             DataTreeModificationOutput.toFile(file, unwrapped);
 268             throw new IllegalStateException(String.format(
 269                     "%s: Failed to apply recovery payload. Modification data was written to file %s",
 270                     logContext, file), e);
 271         }
 272     }
 273
 274     /**
 275      * Apply a payload coming from recovery. This method does not assume the SchemaContexts match and performs data
 276      * pruning in an attempt to adjust the state to our current SchemaContext.
 277      *
 278      * @param payload Payload
 279      * @throws IOException when the snapshot fails to deserialize
 280      * @throws DataValidationFailedException when the snapshot fails to apply
 281      */
 282     void applyRecoveryPayload(final @Nonnull Payload payload) throws IOException, DataValidationFailedException {
 283         if (payload instanceof CommitTransactionPayload) {
 284             final Entry<TransactionIdentifier, DataTreeCandidate> e =
 285                     ((CommitTransactionPayload) payload).getCandidate();
 286             applyRecoveryCandidate(e.getValue());
 287             allMetadataCommittedTransaction(e.getKey());
 288         } else if (payload instanceof DataTreeCandidatePayload) {
 289             applyRecoveryCandidate(((DataTreeCandidatePayload) payload).getCandidate());
 290         } else {
 291             LOG.debug("{}: ignoring unhandled payload {}", logContext, payload);
 292         }
 293     }
 294
 295     private void applyReplicatedCandidate(final Identifier identifier, final DataTreeCandidate foreign)
 296             throws DataValidationFailedException {
 297         LOG.debug("{}: Applying foreign transaction {}", logContext, identifier);
 298
 299         final DataTreeModification mod = dataTree.takeSnapshot().newModification();
 300         DataTreeCandidates.applyToModification(mod, foreign);
 301         mod.ready();
 302
 303         LOG.trace("{}: Applying foreign modification {}", logContext, mod);
 304         dataTree.validate(mod);
 305         final DataTreeCandidate candidate = dataTree.prepare(mod);
 306         dataTree.commit(candidate);
 307
 308         notifyListeners(candidate);
 309     }
 310
 311     /**
 312      * Apply a payload coming from the leader, which could actually be us. This method assumes the leader and follower
 313      * SchemaContexts match and does not perform any pruning.
 314      *
 315      * @param identifier Payload identifier as returned from RaftActor
 316      * @param payload Payload
 317      * @throws IOException when the snapshot fails to deserialize
 318      * @throws DataValidationFailedException when the snapshot fails to apply
 319      */
 320     void applyReplicatedPayload(final Identifier identifier, final Payload payload) throws IOException,
 321             DataValidationFailedException {
 322         /*
 323          * This is a bit more involved than it needs to be due to to the fact we do not want to be touching the payload
 324          * if we are the leader and it has originated with us.
 325          *
 326          * The identifier will only ever be non-null when we were the leader which achieved consensus. Unfortunately,
 327          * though, this may not be the case anymore, as we are being called some time afterwards and we may not be
 328          * acting in that capacity anymore.
 329          *
 330          * In any case, we know that this is an entry coming from replication, hence we can be sure we will not observe
 331          * pre-Boron state -- which limits the number of options here.
 332          */
 333         if (payload instanceof CommitTransactionPayload) {
 334             if (identifier == null) {
 335                 final Entry<TransactionIdentifier, DataTreeCandidate> e =
 336                         ((CommitTransactionPayload) payload).getCandidate();
 337                 applyReplicatedCandidate(e.getKey(), e.getValue());
 338                 allMetadataCommittedTransaction(e.getKey());
 339             } else {
 340                 Verify.verify(identifier instanceof TransactionIdentifier);
 341                 payloadReplicationComplete((TransactionIdentifier) identifier);
 342             }
 343         } else {
 344             LOG.warn("{}: ignoring unhandled identifier {} payload {}", logContext, identifier, payload);
 345         }
 346     }
 347
 348     private void payloadReplicationComplete(final TransactionIdentifier txId) {
 349         final CommitEntry current = pendingTransactions.peek();
 350         if (current == null) {
 351             LOG.warn("{}: No outstanding transactions, ignoring consensus on transaction {}", logContext, txId);
 352             return;
 353         }
 354
 355         if (!current.cohort.getIdentifier().equals(txId)) {
 356             LOG.warn("{}: Head of queue is {}, ignoring consensus on transaction {}", logContext,
 357                 current.cohort.getIdentifier(), txId);
 358             return;
 359         }
 360
 361         finishCommit(current.cohort);
 362     }
 363
 364     private void allMetadataCommittedTransaction(final TransactionIdentifier txId) {
 365         for (ShardDataTreeMetadata<?> m : metadata) {
 366             m.onTransactionCommitted(txId);
 367         }
 368     }
 369
 370     ShardDataTreeTransactionChain ensureTransactionChain(final LocalHistoryIdentifier localHistoryIdentifier) {
 371         ShardDataTreeTransactionChain chain = transactionChains.get(localHistoryIdentifier);
 372         if (chain == null) {
 373             chain = new ShardDataTreeTransactionChain(localHistoryIdentifier, this);
 374             transactionChains.put(localHistoryIdentifier, chain);
 375         }
 376
 377         return chain;
 378     }
 379
 380     ReadOnlyShardDataTreeTransaction newReadOnlyTransaction(final TransactionIdentifier txId) {
 381         if (txId.getHistoryId().getHistoryId() == 0) {
 382             return new ReadOnlyShardDataTreeTransaction(txId, dataTree.takeSnapshot());
 383         }
 384
 385         return ensureTransactionChain(txId.getHistoryId()).newReadOnlyTransaction(txId);
 386     }
 387
 388     ReadWriteShardDataTreeTransaction newReadWriteTransaction(final TransactionIdentifier txId) {
 389         if (txId.getHistoryId().getHistoryId() == 0) {
 390             return new ReadWriteShardDataTreeTransaction(ShardDataTree.this, txId, dataTree.takeSnapshot()
 391                     .newModification());
 392         }
 393
 394         return ensureTransactionChain(txId.getHistoryId()).newReadWriteTransaction(txId);
 395     }
 396
 397     @VisibleForTesting
 398     public void notifyListeners(final DataTreeCandidate candidate) {
 399         treeChangeListenerPublisher.publishChanges(candidate, logContext);
 400         dataChangeListenerPublisher.publishChanges(candidate, logContext);
 401     }
 402
 403     void notifyOfInitialData(final DataChangeListenerRegistration<AsyncDataChangeListener<YangInstanceIdentifier,
 404             NormalizedNode<?, ?>>> listenerReg, final Optional<DataTreeCandidate> currentState) {
 405         if (currentState.isPresent()) {
 406             ShardDataChangeListenerPublisher localPublisher = dataChangeListenerPublisher.newInstance();
 407             localPublisher.registerDataChangeListener(listenerReg.getPath(), listenerReg.getInstance(),
 408                     listenerReg.getScope());
 409             localPublisher.publishChanges(currentState.get(), logContext);
 410         }
 411     }
 412
 413     void notifyOfInitialData(final YangInstanceIdentifier path, final DOMDataTreeChangeListener listener,
 414             final Optional<DataTreeCandidate> currentState) {
 415         if (currentState.isPresent()) {
 416             ShardDataTreeChangeListenerPublisher localPublisher = treeChangeListenerPublisher.newInstance();
 417             localPublisher.registerTreeChangeListener(path, listener);
 418             localPublisher.publishChanges(currentState.get(), logContext);
 419         }
 420     }
 421
 422     void closeAllTransactionChains() {
 423         for (ShardDataTreeTransactionChain chain : transactionChains.values()) {
 424             chain.close();
 425         }
 426
 427         transactionChains.clear();
 428     }
 429
 430     void closeTransactionChain(final LocalHistoryIdentifier transactionChainId) {
 431         final ShardDataTreeTransactionChain chain = transactionChains.remove(transactionChainId);
 432         if (chain != null) {
 433             chain.close();
 434         } else {
 435             LOG.debug("{}: Closing non-existent transaction chain {}", logContext, transactionChainId);
 436         }
 437     }
 438
 439     Entry<DataChangeListenerRegistration<AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>>>,
 440             Optional<DataTreeCandidate>> registerChangeListener(final YangInstanceIdentifier path,
 441                     final AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>> listener,
 442                     final DataChangeScope scope) {
 443         DataChangeListenerRegistration<AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>>> reg =
 444                 dataChangeListenerPublisher.registerDataChangeListener(path, listener, scope);
 445
 446         return new SimpleEntry<>(reg, readCurrentData());
 447     }
 448
 449     private Optional<DataTreeCandidate> readCurrentData() {
 450         final Optional<NormalizedNode<?, ?>> currentState =
 451                 dataTree.takeSnapshot().readNode(YangInstanceIdentifier.EMPTY);
 452         return currentState.isPresent() ? Optional.of(DataTreeCandidates.fromNormalizedNode(
 453             YangInstanceIdentifier.EMPTY, currentState.get())) : Optional.<DataTreeCandidate>absent();
 454     }
 455
 456     public Entry<ListenerRegistration<DOMDataTreeChangeListener>, Optional<DataTreeCandidate>>
 457             registerTreeChangeListener(final YangInstanceIdentifier path, final DOMDataTreeChangeListener listener) {
 458         final ListenerRegistration<DOMDataTreeChangeListener> reg =
 459                 treeChangeListenerPublisher.registerTreeChangeListener(path, listener);
 460
 461         return new SimpleEntry<>(reg, readCurrentData());
 462     }
 463
 464     int getQueueSize() {
 465         return pendingTransactions.size();
 466     }
 467
 468     @Override
 469     void abortTransaction(final AbstractShardDataTreeTransaction<?> transaction) {
 470         // Intentional no-op
 471     }
 472
 473     @Override
 474     ShardDataTreeCohort finishTransaction(final ReadWriteShardDataTreeTransaction transaction) {
 475         final DataTreeModification snapshot = transaction.getSnapshot();
 476         snapshot.ready();
 477
 478         return createReadyCohort(transaction.getIdentifier(), snapshot);
 479     }
 480
 481     public Optional<NormalizedNode<?, ?>> readNode(final YangInstanceIdentifier path) {
 482         return dataTree.takeSnapshot().readNode(path);
 483     }
 484
 485     DataTreeSnapshot takeSnapshot() {
 486         return dataTree.takeSnapshot();
 487     }
 488
 489     @VisibleForTesting
 490     public DataTreeModification newModification() {
 491         return dataTree.takeSnapshot().newModification();
 492     }
 493
 494     /**
 495      * Commits a modification.
 496      *
 497      * @deprecated This method violates DataTree containment and will be removed.
 498      */
 499     @VisibleForTesting
 500     @Deprecated
 501     public DataTreeCandidate commit(final DataTreeModification modification) throws DataValidationFailedException {
 502         modification.ready();
 503         dataTree.validate(modification);
 504         DataTreeCandidate candidate = dataTree.prepare(modification);
 505         dataTree.commit(candidate);
 506         return candidate;
 507     }
 508
 509     public Collection<ShardDataTreeCohort> getAndClearPendingTransactions() {
 510         Collection<ShardDataTreeCohort> ret = new ArrayList<>(pendingTransactions.size());
 511         for (CommitEntry entry: pendingTransactions) {
 512             ret.add(entry.cohort);
 513         }
 514
 515         pendingTransactions.clear();
 516         return ret;
 517     }
 518
 519     @SuppressWarnings("checkstyle:IllegalCatch")
 520     private void processNextTransaction() {
 521         while (!pendingTransactions.isEmpty()) {
 522             final CommitEntry entry = pendingTransactions.peek();
 523             final SimpleShardDataTreeCohort cohort = entry.cohort;
 524             final DataTreeModification modification = cohort.getDataTreeModification();
 525
 526             if (cohort.getState() != State.CAN_COMMIT_PENDING) {
 527                 break;
 528             }
 529
 530             LOG.debug("{}: Validating transaction {}", logContext, cohort.getIdentifier());
 531             Exception cause;
 532             try {
 533                 dataTree.validate(modification);
 534                 LOG.debug("{}: Transaction {} validated", logContext, cohort.getIdentifier());
 535                 cohort.successfulCanCommit();
 536                 entry.lastAccess = shard.ticker().read();
 537                 return;
 538             } catch (ConflictingModificationAppliedException e) {
 539                 LOG.warn("{}: Store Tx {}: Conflicting modification for path {}.", logContext, cohort.getIdentifier(),
 540                     e.getPath());
 541                 cause = new OptimisticLockFailedException("Optimistic lock failed.", e);
 542             } catch (DataValidationFailedException e) {
 543                 LOG.warn("{}: Store Tx {}: Data validation failed for path {}.", logContext, cohort.getIdentifier(),
 544                     e.getPath(), e);
 545
 546                 // For debugging purposes, allow dumping of the modification. Coupled with the above
 547                 // precondition log, it should allow us to understand what went on.
 548                 LOG.debug("{}: Store Tx {}: modifications: {} tree: {}", cohort.getIdentifier(), modification,
 549                         dataTree);
 550                 cause = new TransactionCommitFailedException("Data did not pass validation.", e);
 551             } catch (Exception e) {
 552                 LOG.warn("{}: Unexpected failure in validation phase", logContext, e);
 553                 cause = e;
 554             }
 555
 556             // Failure path: propagate the failure, remove the transaction from the queue and loop to the next one
 557             pendingTransactions.poll().cohort.failedCanCommit(cause);
 558         }
 559
 560         maybeRunOperationOnPendingTransactionsComplete();
 561     }
 562
 563     void startCanCommit(final SimpleShardDataTreeCohort cohort) {
 564         final SimpleShardDataTreeCohort current = pendingTransactions.peek().cohort;
 565         if (!cohort.equals(current)) {
 566             LOG.debug("{}: Transaction {} scheduled for canCommit step", logContext, cohort.getIdentifier());
 567             return;
 568         }
 569
 570         processNextTransaction();
 571     }
 572
 573     private void failPreCommit(final Exception cause) {
 574         shard.getShardMBean().incrementFailedTransactionsCount();
 575         pendingTransactions.poll().cohort.failedPreCommit(cause);
 576         processNextTransaction();
 577     }
 578
 579     @SuppressWarnings("checkstyle:IllegalCatch")
 580     void startPreCommit(final SimpleShardDataTreeCohort cohort) {
 581         final CommitEntry entry = pendingTransactions.peek();
 582         Preconditions.checkState(entry != null, "Attempted to pre-commit of %s when no transactions pending", cohort);
 583
 584         final SimpleShardDataTreeCohort current = entry.cohort;
 585         Verify.verify(cohort.equals(current), "Attempted to pre-commit %s while %s is pending", cohort, current);
 586         final DataTreeCandidateTip candidate;
 587         try {
 588             candidate = dataTree.prepare(cohort.getDataTreeModification());
 589         } catch (Exception e) {
 590             failPreCommit(e);
 591             return;
 592         }
 593
 594         try {
 595             cohort.userPreCommit(candidate);
 596         } catch (ExecutionException | TimeoutException e) {
 597             failPreCommit(e);
 598             return;
 599         }
 600
 601         entry.lastAccess = shard.ticker().read();
 602         cohort.successfulPreCommit(candidate);
 603     }
 604
 605     private void failCommit(final Exception cause) {
 606         shard.getShardMBean().incrementFailedTransactionsCount();
 607         pendingTransactions.poll().cohort.failedCommit(cause);
 608         processNextTransaction();
 609     }
 610
 611     @SuppressWarnings("checkstyle:IllegalCatch")
 612     private void finishCommit(final SimpleShardDataTreeCohort cohort) {
 613         final TransactionIdentifier txId = cohort.getIdentifier();
 614         final DataTreeCandidate candidate = cohort.getCandidate();
 615
 616         LOG.debug("{}: Resuming commit of transaction {}", logContext, txId);
 617
 618         try {
 619             dataTree.commit(candidate);
 620         } catch (Exception e) {
 621             LOG.error("{}: Failed to commit transaction {}", logContext, txId, e);
 622             failCommit(e);
 623             return;
 624         }
 625
 626         shard.getShardMBean().incrementCommittedTransactionCount();
 627         shard.getShardMBean().setLastCommittedTransactionTime(System.currentTimeMillis());
 628
 629         // FIXME: propagate journal index
 630         pendingTransactions.poll().cohort.successfulCommit(UnsignedLong.ZERO);
 631
 632         LOG.trace("{}: Transaction {} committed, proceeding to notify", logContext, txId);
 633         notifyListeners(candidate);
 634
 635         processNextTransaction();
 636     }
 637
 638     void startCommit(final SimpleShardDataTreeCohort cohort, final DataTreeCandidate candidate) {
 639         final CommitEntry entry = pendingTransactions.peek();
 640         Preconditions.checkState(entry != null, "Attempted to start commit of %s when no transactions pending", cohort);
 641
 642         final SimpleShardDataTreeCohort current = entry.cohort;
 643         Verify.verify(cohort.equals(current), "Attempted to commit %s while %s is pending", cohort, current);
 644
 645         if (shard.canSkipPayload() || candidate.getRootNode().getModificationType() == ModificationType.UNMODIFIED) {
 646             LOG.debug("{}: No replication required, proceeding to finish commit", logContext);
 647             finishCommit(cohort);
 648             return;
 649         }
 650
 651         final TransactionIdentifier txId = cohort.getIdentifier();
 652         final Payload payload;
 653         try {
 654             payload = CommitTransactionPayload.create(txId, candidate);
 655         } catch (IOException e) {
 656             LOG.error("{}: Failed to encode transaction {} candidate {}", logContext, txId, candidate, e);
 657             pendingTransactions.poll().cohort.failedCommit(e);
 658             return;
 659         }
 660
 661         // Once completed, we will continue via payloadReplicationComplete
 662         entry.lastAccess = shard.ticker().read();
 663         shard.persistPayload(txId, payload);
 664         LOG.debug("{}: Transaction {} submitted to persistence", logContext, txId);
 665     }
 666
 667     void processCohortRegistryCommand(final ActorRef sender, final CohortRegistryCommand message) {
 668         cohortRegistry.process(sender, message);
 669     }
 670
 671     @Override
 672     ShardDataTreeCohort createReadyCohort(final TransactionIdentifier txId,
 673             final DataTreeModification modification) {
 674         SimpleShardDataTreeCohort cohort = new SimpleShardDataTreeCohort(this, modification, txId,
 675                 cohortRegistry.createCohort(schemaContext, txId, COMMIT_STEP_TIMEOUT));
 676         pendingTransactions.add(new CommitEntry(cohort, shard.ticker().read()));
 677         return cohort;
 678     }
 679
 680     @SuppressFBWarnings(value = {"RV_RETURN_VALUE_IGNORED", "DB_DUPLICATE_SWITCH_CLAUSES"},
 681             justification = "See inline comments below.")
 682     void checkForExpiredTransactions(final long transactionCommitTimeoutMillis) {
 683         final long timeout = TimeUnit.MILLISECONDS.toNanos(transactionCommitTimeoutMillis);
 684         final long now = shard.ticker().read();
 685         final CommitEntry currentTx = pendingTransactions.peek();
 686         if (currentTx != null && currentTx.lastAccess + timeout < now) {
 687             LOG.warn("{}: Current transaction {} has timed out after {} ms in state {}", logContext,
 688                     currentTx.cohort.getIdentifier(), transactionCommitTimeoutMillis, currentTx.cohort.getState());
 689             boolean processNext = true;
 690             switch (currentTx.cohort.getState()) {
 691                 case CAN_COMMIT_PENDING:
 692                     pendingTransactions.poll().cohort.failedCanCommit(new TimeoutException());
 693                     break;
 694                 case CAN_COMMIT_COMPLETE:
 695                     // The suppression of the FindBugs "DB_DUPLICATE_SWITCH_CLAUSES" warning pertains to this clause
 696                     // whose code is duplicated with PRE_COMMIT_COMPLETE. The clauses aren't combined in case the code
 697                     // in PRE_COMMIT_COMPLETE is changed.
 698                     pendingTransactions.poll().cohort.reportFailure(new TimeoutException());
 699                     break;
 700                 case PRE_COMMIT_PENDING:
 701                     pendingTransactions.poll().cohort.failedPreCommit(new TimeoutException());
 702                     break;
 703                 case PRE_COMMIT_COMPLETE:
 704                     // FIXME: this is a legacy behavior problem. Three-phase commit protocol specifies that after we
 705                     //        are ready we should commit the transaction, not abort it. Our current software stack does
 706                     //        not allow us to do that consistently, because we persist at the time of commit, hence
 707                     //        we can end up in a state where we have pre-committed a transaction, then a leader failover
 708                     //        occurred ... the new leader does not see the pre-committed transaction and does not have
 709                     //        a running timer. To fix this we really need two persistence events.
 710                     //
 711                     //        The first one, done at pre-commit time will hold the transaction payload. When consensus
 712                     //        is reached, we exit the pre-commit phase and start the pre-commit timer. Followers do not
 713                     //        apply the state in this event.
 714                     //
 715                     //        The second one, done at commit (or abort) time holds only the transaction identifier and
 716                     //        signals to followers that the state should (or should not) be applied.
 717                     //
 718                     //        In order to make the pre-commit timer working across failovers, though, we need
 719                     //        a per-shard cluster-wide monotonic time, so a follower becoming the leader can accurately
 720                     //        restart the timer.
 721                     pendingTransactions.poll().cohort.reportFailure(new TimeoutException());
 722                     break;
 723                 case COMMIT_PENDING:
 724                     LOG.warn("{}: Transaction {} is still committing, cannot abort", logContext,
 725                         currentTx.cohort.getIdentifier());
 726                     currentTx.lastAccess = now;
 727                     processNext = false;
 728                     return;
 729                 case ABORTED:
 730                 case COMMITTED:
 731                 case FAILED:
 732                 case READY:
 733                 default:
 734                     // The suppression of the FindBugs "RV_RETURN_VALUE_IGNORED" warning pertains to this line. In
 735                     // this case, we just want to drop the current entry that expired and thus ignore the return value.
 736                     // In fact we really shouldn't hit this case but we handle all enums for completeness.
 737                     pendingTransactions.poll();
 738             }
 739
 740             if (processNext) {
 741                 processNextTransaction();
 742             }
 743         }
 744     }
 745
 746     @SuppressFBWarnings(value = "RV_RETURN_VALUE_IGNORED", justification = "See inline comment below.")
 747     void startAbort(final SimpleShardDataTreeCohort cohort) {
 748         final Iterator<CommitEntry> it = pendingTransactions.iterator();
 749         if (!it.hasNext()) {
 750             LOG.debug("{}: no open transaction while attempting to abort {}", logContext, cohort.getIdentifier());
 751             return;
 752         }
 753
 754         // First entry is special, as it may already be committing
 755         final CommitEntry first = it.next();
 756         if (cohort.equals(first.cohort)) {
 757             if (cohort.getState() != State.COMMIT_PENDING) {
 758                 LOG.debug("{}: aborted head of queue {} in state {}", logContext, cohort.getIdentifier(),
 759                     cohort.getIdentifier());
 760
 761                 // The suppression of the FindBugs "RV_RETURN_VALUE_IGNORED" warning pertains to this line. In
 762                 // this case, we've already obtained the head of the queue above via the Iterator and we just want to
 763                 // remove it here.
 764                 pendingTransactions.poll();
 765                 processNextTransaction();
 766             } else {
 767                 LOG.warn("{}: transaction {} is committing, skipping abort", logContext, cohort.getIdentifier());
 768             }
 769
 770             return;
 771         }
 772
 773         while (it.hasNext()) {
 774             final CommitEntry e = it.next();
 775             if (cohort.equals(e.cohort)) {
 776                 LOG.debug("{}: aborting queued transaction {}", logContext, cohort.getIdentifier());
 777                 it.remove();
 778                 return;
 779             }
 780         }
 781
 782         LOG.debug("{}: aborted transaction {} not found in the queue", logContext, cohort.getIdentifier());
 783     }
 784
 785     void setRunOnPendingTransactionsComplete(final Runnable operation) {
 786         runOnPendingTransactionsComplete = operation;
 787         maybeRunOperationOnPendingTransactionsComplete();
 788     }
 789
 790     private void maybeRunOperationOnPendingTransactionsComplete() {
 791         if (runOnPendingTransactionsComplete != null && pendingTransactions.isEmpty()) {
 792             LOG.debug("{}: Pending transactions complete - running operation {}", logContext,
 793                     runOnPendingTransactionsComplete);
 794
 795             runOnPendingTransactionsComplete.run();
 796             runOnPendingTransactionsComplete = null;
 797         }
 798     }
 799 }