opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/TransactionProxy.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.ActorSelection;
  12 import akka.dispatch.OnComplete;
  13
  14 import com.google.common.annotations.VisibleForTesting;
  15 import com.google.common.base.FinalizablePhantomReference;
  16 import com.google.common.base.FinalizableReferenceQueue;
  17 import com.google.common.base.Optional;
  18 import com.google.common.base.Preconditions;
  19 import com.google.common.collect.Lists;
  20 import com.google.common.util.concurrent.CheckedFuture;
  21 import com.google.common.util.concurrent.Futures;
  22 import com.google.common.util.concurrent.SettableFuture;
  23
  24 import org.opendaylight.controller.cluster.datastore.exceptions.PrimaryNotFoundException;
  25 import org.opendaylight.controller.cluster.datastore.identifiers.TransactionIdentifier;
  26 import org.opendaylight.controller.cluster.datastore.messages.CloseTransaction;
  27 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  28 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  29 import org.opendaylight.controller.cluster.datastore.messages.DataExists;
  30 import org.opendaylight.controller.cluster.datastore.messages.DataExistsReply;
  31 import org.opendaylight.controller.cluster.datastore.messages.DeleteData;
  32 import org.opendaylight.controller.cluster.datastore.messages.MergeData;
  33 import org.opendaylight.controller.cluster.datastore.messages.ReadData;
  34 import org.opendaylight.controller.cluster.datastore.messages.ReadDataReply;
  35 import org.opendaylight.controller.cluster.datastore.messages.ReadyTransaction;
  36 import org.opendaylight.controller.cluster.datastore.messages.ReadyTransactionReply;
  37 import org.opendaylight.controller.cluster.datastore.messages.WriteData;
  38 import org.opendaylight.controller.cluster.datastore.shardstrategy.ShardStrategyFactory;
  39 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
  40 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
  41 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadWriteTransaction;
  42 import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
  43 import org.opendaylight.yangtools.util.concurrent.MappingCheckedFuture;
  44 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  45 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  46 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  47 import org.slf4j.Logger;
  48 import org.slf4j.LoggerFactory;
  49
  50 import scala.Function1;
  51 import scala.concurrent.Future;
  52 import scala.runtime.AbstractFunction1;
  53
  54 import java.util.HashMap;
  55 import java.util.List;
  56 import java.util.Map;
  57 import java.util.concurrent.ConcurrentHashMap;
  58 import java.util.concurrent.atomic.AtomicBoolean;
  59 import java.util.concurrent.atomic.AtomicLong;
  60
  61 /**
  62  * TransactionProxy acts as a proxy for one or more transactions that were created on a remote shard
  63  * <p>
  64  * Creating a transaction on the consumer side will create one instance of a transaction proxy. If during
  65  * the transaction reads and writes are done on data that belongs to different shards then a separate transaction will
  66  * be created on each of those shards by the TransactionProxy
  67  *</p>
  68  * <p>
  69  * The TransactionProxy does not make any guarantees about atomicity or order in which the transactions on the various
  70  * shards will be executed.
  71  * </p>
  72  */
  73 public class TransactionProxy implements DOMStoreReadWriteTransaction {
  74
  75     private final TransactionChainProxy transactionChainProxy;
  76
  77
  78
  79     public enum TransactionType {
  80         READ_ONLY,
  81         WRITE_ONLY,
  82         READ_WRITE
  83     }
  84
  85     static Function1<Throwable, Throwable> SAME_FAILURE_TRANSFORMER = new AbstractFunction1<
  86                                                                           Throwable, Throwable>() {
  87         @Override
  88         public Throwable apply(Throwable failure) {
  89             return failure;
  90         }
  91     };
  92
  93     private static final AtomicLong counter = new AtomicLong();
  94
  95     private static final Logger
  96         LOG = LoggerFactory.getLogger(TransactionProxy.class);
  97
  98
  99     /**
 100      * Used to enqueue the PhantomReferences for read-only TransactionProxy instances. The
 101      * FinalizableReferenceQueue is safe to use statically in an OSGi environment as it uses some
 102      * trickery to clean up its internal thread when the bundle is unloaded.
 103      */
 104     private static final FinalizableReferenceQueue phantomReferenceQueue =
 105                                                                   new FinalizableReferenceQueue();
 106
 107     /**
 108      * This stores the TransactionProxyCleanupPhantomReference instances statically, This is
 109      * necessary because PhantomReferences need a hard reference so they're not garbage collected.
 110      * Once finalized, the TransactionProxyCleanupPhantomReference removes itself from this map
 111      * and thus becomes eligible for garbage collection.
 112      */
 113     private static final Map<TransactionProxyCleanupPhantomReference,
 114                              TransactionProxyCleanupPhantomReference> phantomReferenceCache =
 115                                                                         new ConcurrentHashMap<>();
 116
 117     /**
 118      * A PhantomReference that closes remote transactions for a TransactionProxy when it's
 119      * garbage collected. This is used for read-only transactions as they're not explicitly closed
 120      * by clients. So the only way to detect that a transaction is no longer in use and it's safe
 121      * to clean up is when it's garbage collected. It's inexact as to when an instance will be GC'ed
 122      * but TransactionProxy instances should generally be short-lived enough to avoid being moved
 123      * to the old generation space and thus should be cleaned up in a timely manner as the GC
 124      * runs on the young generation (eden, swap1...) space much more frequently.
 125      */
 126     private static class TransactionProxyCleanupPhantomReference
 127                                            extends FinalizablePhantomReference<TransactionProxy> {
 128
 129         private final List<ActorSelection> remoteTransactionActors;
 130         private final AtomicBoolean remoteTransactionActorsMB;
 131         private final ActorContext actorContext;
 132         private final TransactionIdentifier identifier;
 133
 134         protected TransactionProxyCleanupPhantomReference(TransactionProxy referent) {
 135             super(referent, phantomReferenceQueue);
 136
 137             // Note we need to cache the relevant fields from the TransactionProxy as we can't
 138             // have a hard reference to the TransactionProxy instance itself.
 139
 140             remoteTransactionActors = referent.remoteTransactionActors;
 141             remoteTransactionActorsMB = referent.remoteTransactionActorsMB;
 142             actorContext = referent.actorContext;
 143             identifier = referent.identifier;
 144         }
 145
 146         @Override
 147         public void finalizeReferent() {
 148             LOG.trace("Cleaning up {} Tx actors for TransactionProxy {}",
 149                     remoteTransactionActors.size(), identifier);
 150
 151             phantomReferenceCache.remove(this);
 152
 153             // Access the memory barrier volatile to ensure all previous updates to the
 154             // remoteTransactionActors list are visible to this thread.
 155
 156             if(remoteTransactionActorsMB.get()) {
 157                 for(ActorSelection actor : remoteTransactionActors) {
 158                     LOG.trace("Sending CloseTransaction to {}", actor);
 159                     actorContext.sendOperationAsync(actor,
 160                             new CloseTransaction().toSerializable());
 161                 }
 162             }
 163         }
 164     }
 165
 166     /**
 167      * Stores the remote Tx actors for each requested data store path to be used by the
 168      * PhantomReference to close the remote Tx's. This is only used for read-only Tx's. The
 169      * remoteTransactionActorsMB volatile serves as a memory barrier to publish updates to the
 170      * remoteTransactionActors list so they will be visible to the thread accessing the
 171      * PhantomReference.
 172      */
 173     private List<ActorSelection> remoteTransactionActors;
 174     private AtomicBoolean remoteTransactionActorsMB;
 175
 176     private final Map<String, TransactionContext> remoteTransactionPaths = new HashMap<>();
 177
 178     private final TransactionType transactionType;
 179     private final ActorContext actorContext;
 180     private final TransactionIdentifier identifier;
 181     private final SchemaContext schemaContext;
 182     private boolean inReadyState;
 183
 184     public TransactionProxy(ActorContext actorContext, TransactionType transactionType) {
 185         this(actorContext, transactionType, null);
 186     }
 187
 188     @VisibleForTesting
 189     List<Future<Object>> getRecordedOperationFutures() {
 190         List<Future<Object>> recordedOperationFutures = Lists.newArrayList();
 191         for(TransactionContext transactionContext : remoteTransactionPaths.values()) {
 192             recordedOperationFutures.addAll(transactionContext.getRecordedOperationFutures());
 193         }
 194
 195         return recordedOperationFutures;
 196     }
 197
 198     public TransactionProxy(ActorContext actorContext, TransactionType transactionType, TransactionChainProxy transactionChainProxy) {
 199         this.actorContext = Preconditions.checkNotNull(actorContext,
 200             "actorContext should not be null");
 201         this.transactionType = Preconditions.checkNotNull(transactionType,
 202             "transactionType should not be null");
 203         this.schemaContext = Preconditions.checkNotNull(actorContext.getSchemaContext(),
 204             "schemaContext should not be null");
 205         this.transactionChainProxy = transactionChainProxy;
 206
 207         String memberName = actorContext.getCurrentMemberName();
 208         if(memberName == null){
 209             memberName = "UNKNOWN-MEMBER";
 210         }
 211
 212         this.identifier = TransactionIdentifier.builder().memberName(memberName).counter(
 213             counter.getAndIncrement()).build();
 214
 215         if(transactionType == TransactionType.READ_ONLY) {
 216             // Read-only Tx's aren't explicitly closed by the client so we create a PhantomReference
 217             // to close the remote Tx's when this instance is no longer in use and is garbage
 218             // collected.
 219
 220             remoteTransactionActors = Lists.newArrayList();
 221             remoteTransactionActorsMB = new AtomicBoolean();
 222
 223             TransactionProxyCleanupPhantomReference cleanup =
 224                 new TransactionProxyCleanupPhantomReference(this);
 225             phantomReferenceCache.put(cleanup, cleanup);
 226         }
 227         if(LOG.isDebugEnabled()) {
 228             LOG.debug("Created txn {} of type {}", identifier, transactionType);
 229         }
 230     }
 231
 232     @Override
 233     public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> read(
 234             final YangInstanceIdentifier path) {
 235
 236         Preconditions.checkState(transactionType != TransactionType.WRITE_ONLY,
 237                 "Read operation on write-only transaction is not allowed");
 238
 239         if(LOG.isDebugEnabled()) {
 240             LOG.debug("Tx {} read {}", identifier, path);
 241         }
 242         createTransactionIfMissing(actorContext, path);
 243
 244         return transactionContext(path).readData(path);
 245     }
 246
 247     @Override
 248     public CheckedFuture<Boolean, ReadFailedException> exists(YangInstanceIdentifier path) {
 249
 250         Preconditions.checkState(transactionType != TransactionType.WRITE_ONLY,
 251                 "Exists operation on write-only transaction is not allowed");
 252
 253         if(LOG.isDebugEnabled()) {
 254             LOG.debug("Tx {} exists {}", identifier, path);
 255         }
 256         createTransactionIfMissing(actorContext, path);
 257
 258         return transactionContext(path).dataExists(path);
 259     }
 260
 261     private void checkModificationState() {
 262         Preconditions.checkState(transactionType != TransactionType.READ_ONLY,
 263                 "Modification operation on read-only transaction is not allowed");
 264         Preconditions.checkState(!inReadyState,
 265                 "Transaction is sealed - further modifications are not allowed");
 266     }
 267
 268     @Override
 269     public void write(YangInstanceIdentifier path, NormalizedNode<?, ?> data) {
 270
 271         checkModificationState();
 272
 273         if(LOG.isDebugEnabled()) {
 274             LOG.debug("Tx {} write {}", identifier, path);
 275         }
 276         createTransactionIfMissing(actorContext, path);
 277
 278         transactionContext(path).writeData(path, data);
 279     }
 280
 281     @Override
 282     public void merge(YangInstanceIdentifier path, NormalizedNode<?, ?> data) {
 283
 284         checkModificationState();
 285
 286         if(LOG.isDebugEnabled()) {
 287             LOG.debug("Tx {} merge {}", identifier, path);
 288         }
 289         createTransactionIfMissing(actorContext, path);
 290
 291         transactionContext(path).mergeData(path, data);
 292     }
 293
 294     @Override
 295     public void delete(YangInstanceIdentifier path) {
 296
 297         checkModificationState();
 298         if(LOG.isDebugEnabled()) {
 299             LOG.debug("Tx {} delete {}", identifier, path);
 300         }
 301         createTransactionIfMissing(actorContext, path);
 302
 303         transactionContext(path).deleteData(path);
 304     }
 305
 306     @Override
 307     public DOMStoreThreePhaseCommitCohort ready() {
 308
 309         checkModificationState();
 310
 311         inReadyState = true;
 312
 313         if(LOG.isDebugEnabled()) {
 314             LOG.debug("Tx {} Trying to get {} transactions ready for commit", identifier,
 315                 remoteTransactionPaths.size());
 316         }
 317         List<Future<ActorSelection>> cohortFutures = Lists.newArrayList();
 318
 319         for(TransactionContext transactionContext : remoteTransactionPaths.values()) {
 320
 321             if(LOG.isDebugEnabled()) {
 322                 LOG.debug("Tx {} Readying transaction for shard {}", identifier,
 323                     transactionContext.getShardName());
 324             }
 325             cohortFutures.add(transactionContext.readyTransaction());
 326         }
 327
 328         if(transactionChainProxy != null){
 329             transactionChainProxy.onTransactionReady(cohortFutures);
 330         }
 331
 332         return new ThreePhaseCommitCohortProxy(actorContext, cohortFutures,
 333                 identifier.toString());
 334     }
 335
 336     @Override
 337     public Object getIdentifier() {
 338         return this.identifier;
 339     }
 340
 341     @Override
 342     public void close() {
 343         for(TransactionContext transactionContext : remoteTransactionPaths.values()) {
 344             transactionContext.closeTransaction();
 345         }
 346
 347         remoteTransactionPaths.clear();
 348
 349         if(transactionType == TransactionType.READ_ONLY) {
 350             remoteTransactionActors.clear();
 351             remoteTransactionActorsMB.set(true);
 352         }
 353     }
 354
 355     private TransactionContext transactionContext(YangInstanceIdentifier path){
 356         String shardName = shardNameFromIdentifier(path);
 357         return remoteTransactionPaths.get(shardName);
 358     }
 359
 360     private String shardNameFromIdentifier(YangInstanceIdentifier path){
 361         return ShardStrategyFactory.getStrategy(path).findShard(path);
 362     }
 363
 364     private void createTransactionIfMissing(ActorContext actorContext,
 365         YangInstanceIdentifier path) {
 366
 367         if(transactionChainProxy != null){
 368             transactionChainProxy.waitTillCurrentTransactionReady();
 369         }
 370
 371         String shardName = ShardStrategyFactory.getStrategy(path).findShard(path);
 372
 373         TransactionContext transactionContext =
 374             remoteTransactionPaths.get(shardName);
 375
 376         if (transactionContext != null) {
 377             // A transaction already exists with that shard
 378             return;
 379         }
 380
 381         try {
 382             Optional<ActorSelection> primaryShard = actorContext.findPrimaryShard(shardName);
 383             if (!primaryShard.isPresent()) {
 384                 throw new PrimaryNotFoundException("Primary could not be found for shard " + shardName);
 385             }
 386
 387             Object response = actorContext.executeOperation(primaryShard.get(),
 388                     new CreateTransaction(identifier.toString(), this.transactionType.ordinal(),
 389                             getTransactionChainId()).toSerializable());
 390             if (response.getClass().equals(CreateTransactionReply.SERIALIZABLE_CLASS)) {
 391                 CreateTransactionReply reply =
 392                     CreateTransactionReply.fromSerializable(response);
 393
 394                 String transactionPath = reply.getTransactionPath();
 395
 396                 if(LOG.isDebugEnabled()) {
 397                     LOG.debug("Tx {} Received transaction path = {}", identifier, transactionPath);
 398                 }
 399                 ActorSelection transactionActor = actorContext.actorSelection(transactionPath);
 400
 401                 if (transactionType == TransactionType.READ_ONLY) {
 402                     // Add the actor to the remoteTransactionActors list for access by the
 403                     // cleanup PhantonReference.
 404                     remoteTransactionActors.add(transactionActor);
 405
 406                     // Write to the memory barrier volatile to publish the above update to the
 407                     // remoteTransactionActors list for thread visibility.
 408                     remoteTransactionActorsMB.set(true);
 409                 }
 410
 411                 transactionContext = new TransactionContextImpl(shardName, transactionPath,
 412                     transactionActor, identifier, actorContext, schemaContext);
 413
 414                 remoteTransactionPaths.put(shardName, transactionContext);
 415             } else {
 416                 throw new IllegalArgumentException(String.format(
 417                     "Invalid reply type {} for CreateTransaction", response.getClass()));
 418             }
 419         } catch (Exception e) {
 420             if(LOG.isDebugEnabled()) {
 421                 LOG.debug("Tx {} Creating NoOpTransaction because of : {}", identifier, e.getMessage());
 422             }
 423             remoteTransactionPaths
 424                 .put(shardName, new NoOpTransactionContext(shardName, e, identifier));
 425         }
 426     }
 427
 428     public String getTransactionChainId() {
 429         if(transactionChainProxy == null){
 430             return "";
 431         }
 432         return transactionChainProxy.getTransactionChainId();
 433     }
 434
 435
 436     private interface TransactionContext {
 437         String getShardName();
 438
 439         void closeTransaction();
 440
 441         Future<ActorSelection> readyTransaction();
 442
 443         void writeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data);
 444
 445         void deleteData(YangInstanceIdentifier path);
 446
 447         void mergeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data);
 448
 449         CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> readData(
 450                 final YangInstanceIdentifier path);
 451
 452         CheckedFuture<Boolean, ReadFailedException> dataExists(YangInstanceIdentifier path);
 453
 454         List<Future<Object>> getRecordedOperationFutures();
 455     }
 456
 457     private static abstract class AbstractTransactionContext implements TransactionContext {
 458
 459         protected final TransactionIdentifier identifier;
 460         protected final String shardName;
 461         protected final List<Future<Object>> recordedOperationFutures = Lists.newArrayList();
 462
 463         AbstractTransactionContext(String shardName, TransactionIdentifier identifier) {
 464             this.shardName = shardName;
 465             this.identifier = identifier;
 466         }
 467
 468         @Override
 469         public String getShardName() {
 470             return shardName;
 471         }
 472
 473         @Override
 474         public List<Future<Object>> getRecordedOperationFutures() {
 475             return recordedOperationFutures;
 476         }
 477     }
 478
 479     private static class TransactionContextImpl extends AbstractTransactionContext {
 480         private final Logger LOG = LoggerFactory.getLogger(TransactionContextImpl.class);
 481
 482         private final ActorContext actorContext;
 483         private final SchemaContext schemaContext;
 484         private final String actorPath;
 485         private final ActorSelection actor;
 486
 487         private TransactionContextImpl(String shardName, String actorPath,
 488                 ActorSelection actor, TransactionIdentifier identifier, ActorContext actorContext,
 489                 SchemaContext schemaContext) {
 490             super(shardName, identifier);
 491             this.actorPath = actorPath;
 492             this.actor = actor;
 493             this.actorContext = actorContext;
 494             this.schemaContext = schemaContext;
 495         }
 496
 497         private ActorSelection getActor() {
 498             return actor;
 499         }
 500
 501         @Override
 502         public void closeTransaction() {
 503             if(LOG.isDebugEnabled()) {
 504                 LOG.debug("Tx {} closeTransaction called", identifier);
 505             }
 506             actorContext.sendOperationAsync(getActor(), new CloseTransaction().toSerializable());
 507         }
 508
 509         @Override
 510         public Future<ActorSelection> readyTransaction() {
 511             if(LOG.isDebugEnabled()) {
 512                 LOG.debug("Tx {} readyTransaction called with {} previous recorded operations pending",
 513                     identifier, recordedOperationFutures.size());
 514             }
 515             // Send the ReadyTransaction message to the Tx actor.
 516
 517             final Future<Object> replyFuture = actorContext.executeOperationAsync(getActor(),
 518                     new ReadyTransaction().toSerializable());
 519
 520             // Combine all the previously recorded put/merge/delete operation reply Futures and the
 521             // ReadyTransactionReply Future into one Future. If any one fails then the combined
 522             // Future will fail. We need all prior operations and the ready operation to succeed
 523             // in order to attempt commit.
 524
 525             List<Future<Object>> futureList =
 526                     Lists.newArrayListWithCapacity(recordedOperationFutures.size() + 1);
 527             futureList.addAll(recordedOperationFutures);
 528             futureList.add(replyFuture);
 529
 530             Future<Iterable<Object>> combinedFutures = akka.dispatch.Futures.sequence(futureList,
 531                     actorContext.getActorSystem().dispatcher());
 532
 533             // Transform the combined Future into a Future that returns the cohort actor path from
 534             // the ReadyTransactionReply. That's the end result of the ready operation.
 535
 536             return combinedFutures.transform(new AbstractFunction1<Iterable<Object>, ActorSelection>() {
 537                 @Override
 538                 public ActorSelection apply(Iterable<Object> notUsed) {
 539                     if(LOG.isDebugEnabled()) {
 540                         LOG.debug("Tx {} readyTransaction: pending recorded operations succeeded",
 541                             identifier);
 542                     }
 543                     // At this point all the Futures succeeded and we need to extract the cohort
 544                     // actor path from the ReadyTransactionReply. For the recorded operations, they
 545                     // don't return any data so we're only interested that they completed
 546                     // successfully. We could be paranoid and verify the correct reply types but
 547                     // that really should never happen so it's not worth the overhead of
 548                     // de-serializing each reply.
 549
 550                     // Note the Future get call here won't block as it's complete.
 551                     Object serializedReadyReply = replyFuture.value().get().get();
 552                     if(serializedReadyReply.getClass().equals(
 553                                                      ReadyTransactionReply.SERIALIZABLE_CLASS)) {
 554                         ReadyTransactionReply reply = ReadyTransactionReply.fromSerializable(
 555                                serializedReadyReply);
 556
 557                         return actorContext.actorSelection(reply.getCohortPath());
 558                     } else {
 559                         // Throwing an exception here will fail the Future.
 560
 561                         throw new IllegalArgumentException(String.format("Invalid reply type {}",
 562                                 serializedReadyReply.getClass()));
 563                     }
 564                 }
 565             }, SAME_FAILURE_TRANSFORMER, actorContext.getActorSystem().dispatcher());
 566         }
 567
 568         @Override
 569         public void deleteData(YangInstanceIdentifier path) {
 570             if(LOG.isDebugEnabled()) {
 571                 LOG.debug("Tx {} deleteData called path = {}", identifier, path);
 572             }
 573             recordedOperationFutures.add(actorContext.executeOperationAsync(getActor(),
 574                     new DeleteData(path).toSerializable()));
 575         }
 576
 577         @Override
 578         public void mergeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data) {
 579             if(LOG.isDebugEnabled()) {
 580                 LOG.debug("Tx {} mergeData called path = {}", identifier, path);
 581             }
 582             recordedOperationFutures.add(actorContext.executeOperationAsync(getActor(),
 583                     new MergeData(path, data, schemaContext).toSerializable()));
 584         }
 585
 586         @Override
 587         public void writeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data) {
 588             if(LOG.isDebugEnabled()) {
 589                 LOG.debug("Tx {} writeData called path = {}", identifier, path);
 590             }
 591             recordedOperationFutures.add(actorContext.executeOperationAsync(getActor(),
 592                     new WriteData(path, data, schemaContext).toSerializable()));
 593         }
 594
 595         @Override
 596         public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> readData(
 597                 final YangInstanceIdentifier path) {
 598
 599             if(LOG.isDebugEnabled()) {
 600                 LOG.debug("Tx {} readData called path = {}", identifier, path);
 601             }
 602             final SettableFuture<Optional<NormalizedNode<?, ?>>> returnFuture = SettableFuture.create();
 603
 604             // If there were any previous recorded put/merge/delete operation reply Futures then we
 605             // must wait for them to successfully complete. This is necessary to honor the read
 606             // uncommitted semantics of the public API contract. If any one fails then fail the read.
 607
 608             if(recordedOperationFutures.isEmpty()) {
 609                 finishReadData(path, returnFuture);
 610             } else {
 611                 if(LOG.isDebugEnabled()) {
 612                     LOG.debug("Tx {} readData: verifying {} previous recorded operations",
 613                         identifier, recordedOperationFutures.size());
 614                 }
 615                 // Note: we make a copy of recordedOperationFutures to be on the safe side in case
 616                 // Futures#sequence accesses the passed List on a different thread, as
 617                 // recordedOperationFutures is not synchronized.
 618
 619                 Future<Iterable<Object>> combinedFutures = akka.dispatch.Futures.sequence(
 620                         Lists.newArrayList(recordedOperationFutures),
 621                         actorContext.getActorSystem().dispatcher());
 622                 OnComplete<Iterable<Object>> onComplete = new OnComplete<Iterable<Object>>() {
 623                     @Override
 624                     public void onComplete(Throwable failure, Iterable<Object> notUsed)
 625                             throws Throwable {
 626                         if(failure != null) {
 627                             if(LOG.isDebugEnabled()) {
 628                                 LOG.debug("Tx {} readData: a recorded operation failed: {}",
 629                                     identifier, failure);
 630                             }
 631                             returnFuture.setException(new ReadFailedException(
 632                                     "The read could not be performed because a previous put, merge,"
 633                                     + "or delete operation failed", failure));
 634                         } else {
 635                             finishReadData(path, returnFuture);
 636                         }
 637                     }
 638                 };
 639
 640                 combinedFutures.onComplete(onComplete, actorContext.getActorSystem().dispatcher());
 641             }
 642
 643             return MappingCheckedFuture.create(returnFuture, ReadFailedException.MAPPER);
 644         }
 645
 646         private void finishReadData(final YangInstanceIdentifier path,
 647                 final SettableFuture<Optional<NormalizedNode<?, ?>>> returnFuture) {
 648
 649             if(LOG.isDebugEnabled()) {
 650                 LOG.debug("Tx {} finishReadData called path = {}", identifier, path);
 651             }
 652             OnComplete<Object> onComplete = new OnComplete<Object>() {
 653                 @Override
 654                 public void onComplete(Throwable failure, Object readResponse) throws Throwable {
 655                     if(failure != null) {
 656                         if(LOG.isDebugEnabled()) {
 657                             LOG.debug("Tx {} read operation failed: {}", identifier, failure);
 658                         }
 659                         returnFuture.setException(new ReadFailedException(
 660                                 "Error reading data for path " + path, failure));
 661
 662                     } else {
 663                         if(LOG.isDebugEnabled()) {
 664                             LOG.debug("Tx {} read operation succeeded", identifier, failure);
 665                         }
 666                         if (readResponse.getClass().equals(ReadDataReply.SERIALIZABLE_CLASS)) {
 667                             ReadDataReply reply = ReadDataReply.fromSerializable(schemaContext,
 668                                     path, readResponse);
 669                             if (reply.getNormalizedNode() == null) {
 670                                 returnFuture.set(Optional.<NormalizedNode<?, ?>>absent());
 671                             } else {
 672                                 returnFuture.set(Optional.<NormalizedNode<?, ?>>of(
 673                                         reply.getNormalizedNode()));
 674                             }
 675                         } else {
 676                             returnFuture.setException(new ReadFailedException(
 677                                     "Invalid response reading data for path " + path));
 678                         }
 679                     }
 680                 }
 681             };
 682
 683             Future<Object> readFuture = actorContext.executeOperationAsync(getActor(),
 684                     new ReadData(path).toSerializable());
 685             readFuture.onComplete(onComplete, actorContext.getActorSystem().dispatcher());
 686         }
 687
 688         @Override
 689         public CheckedFuture<Boolean, ReadFailedException> dataExists(
 690                 final YangInstanceIdentifier path) {
 691
 692             if(LOG.isDebugEnabled()) {
 693                 LOG.debug("Tx {} dataExists called path = {}", identifier, path);
 694             }
 695             final SettableFuture<Boolean> returnFuture = SettableFuture.create();
 696
 697             // If there were any previous recorded put/merge/delete operation reply Futures then we
 698             // must wait for them to successfully complete. This is necessary to honor the read
 699             // uncommitted semantics of the public API contract. If any one fails then fail this
 700             // request.
 701
 702             if(recordedOperationFutures.isEmpty()) {
 703                 finishDataExists(path, returnFuture);
 704             } else {
 705                 if(LOG.isDebugEnabled()) {
 706                     LOG.debug("Tx {} dataExists: verifying {} previous recorded operations",
 707                         identifier, recordedOperationFutures.size());
 708                 }
 709                 // Note: we make a copy of recordedOperationFutures to be on the safe side in case
 710                 // Futures#sequence accesses the passed List on a different thread, as
 711                 // recordedOperationFutures is not synchronized.
 712
 713                 Future<Iterable<Object>> combinedFutures = akka.dispatch.Futures.sequence(
 714                         Lists.newArrayList(recordedOperationFutures),
 715                         actorContext.getActorSystem().dispatcher());
 716                 OnComplete<Iterable<Object>> onComplete = new OnComplete<Iterable<Object>>() {
 717                     @Override
 718                     public void onComplete(Throwable failure, Iterable<Object> notUsed)
 719                             throws Throwable {
 720                         if(failure != null) {
 721                             if(LOG.isDebugEnabled()) {
 722                                 LOG.debug("Tx {} dataExists: a recorded operation failed: {}",
 723                                     identifier, failure);
 724                             }
 725                             returnFuture.setException(new ReadFailedException(
 726                                     "The data exists could not be performed because a previous "
 727                                     + "put, merge, or delete operation failed", failure));
 728                         } else {
 729                             finishDataExists(path, returnFuture);
 730                         }
 731                     }
 732                 };
 733
 734                 combinedFutures.onComplete(onComplete, actorContext.getActorSystem().dispatcher());
 735             }
 736
 737             return MappingCheckedFuture.create(returnFuture, ReadFailedException.MAPPER);
 738         }
 739
 740         private void finishDataExists(final YangInstanceIdentifier path,
 741                 final SettableFuture<Boolean> returnFuture) {
 742
 743             if(LOG.isDebugEnabled()) {
 744                 LOG.debug("Tx {} finishDataExists called path = {}", identifier, path);
 745             }
 746             OnComplete<Object> onComplete = new OnComplete<Object>() {
 747                 @Override
 748                 public void onComplete(Throwable failure, Object response) throws Throwable {
 749                     if(failure != null) {
 750                         if(LOG.isDebugEnabled()) {
 751                             LOG.debug("Tx {} dataExists operation failed: {}", identifier, failure);
 752                         }
 753                         returnFuture.setException(new ReadFailedException(
 754                                 "Error checking data exists for path " + path, failure));
 755                     } else {
 756                         if(LOG.isDebugEnabled()) {
 757                             LOG.debug("Tx {} dataExists operation succeeded", identifier, failure);
 758                         }
 759                         if (response.getClass().equals(DataExistsReply.SERIALIZABLE_CLASS)) {
 760                             returnFuture.set(Boolean.valueOf(DataExistsReply.
 761                                         fromSerializable(response).exists()));
 762                         } else {
 763                             returnFuture.setException(new ReadFailedException(
 764                                     "Invalid response checking exists for path " + path));
 765                         }
 766                     }
 767                 }
 768             };
 769
 770             Future<Object> future = actorContext.executeOperationAsync(getActor(),
 771                     new DataExists(path).toSerializable());
 772             future.onComplete(onComplete, actorContext.getActorSystem().dispatcher());
 773         }
 774     }
 775
 776     private static class NoOpTransactionContext extends AbstractTransactionContext {
 777
 778         private final Logger LOG = LoggerFactory.getLogger(NoOpTransactionContext.class);
 779
 780         private final Exception failure;
 781
 782         public NoOpTransactionContext(String shardName, Exception failure,
 783                 TransactionIdentifier identifier){
 784             super(shardName, identifier);
 785             this.failure = failure;
 786         }
 787
 788         @Override
 789         public void closeTransaction() {
 790             if(LOG.isDebugEnabled()) {
 791                 LOG.debug("NoOpTransactionContext {} closeTransaction called", identifier);
 792             }
 793         }
 794
 795         @Override
 796         public Future<ActorSelection> readyTransaction() {
 797             if(LOG.isDebugEnabled()) {
 798                 LOG.debug("Tx {} readyTransaction called", identifier);
 799             }
 800             return akka.dispatch.Futures.failed(failure);
 801         }
 802
 803         @Override
 804         public void deleteData(YangInstanceIdentifier path) {
 805             if(LOG.isDebugEnabled()) {
 806                 LOG.debug("Tx {} deleteData called path = {}", identifier, path);
 807             }
 808         }
 809
 810         @Override
 811         public void mergeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data) {
 812             if(LOG.isDebugEnabled()) {
 813                 LOG.debug("Tx {} mergeData called path = {}", identifier, path);
 814             }
 815         }
 816
 817         @Override
 818         public void writeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data) {
 819             if(LOG.isDebugEnabled()) {
 820                 LOG.debug("Tx {} writeData called path = {}", identifier, path);
 821             }
 822         }
 823
 824         @Override
 825         public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> readData(
 826             YangInstanceIdentifier path) {
 827             if(LOG.isDebugEnabled()) {
 828                 LOG.debug("Tx {} readData called path = {}", identifier, path);
 829             }
 830             return Futures.immediateFailedCheckedFuture(new ReadFailedException(
 831                     "Error reading data for path " + path, failure));
 832         }
 833
 834         @Override
 835         public CheckedFuture<Boolean, ReadFailedException> dataExists(
 836             YangInstanceIdentifier path) {
 837             if(LOG.isDebugEnabled()) {
 838                 LOG.debug("Tx {} dataExists called path = {}", identifier, path);
 839             }
 840             return Futures.immediateFailedCheckedFuture(new ReadFailedException(
 841                     "Error checking exists for path " + path, failure));
 842         }
 843     }
 844 }