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.Mapper;
  13 import akka.dispatch.OnComplete;
  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.FutureCallback;
  22 import com.google.common.util.concurrent.Futures;
  23 import com.google.common.util.concurrent.SettableFuture;
  24 import java.util.HashMap;
  25 import java.util.List;
  26 import java.util.Map;
  27 import java.util.concurrent.ConcurrentHashMap;
  28 import java.util.concurrent.TimeUnit;
  29 import java.util.concurrent.atomic.AtomicBoolean;
  30 import java.util.concurrent.atomic.AtomicLong;
  31 import javax.annotation.concurrent.GuardedBy;
  32 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  33 import org.opendaylight.controller.cluster.datastore.identifiers.TransactionIdentifier;
  34 import org.opendaylight.controller.cluster.datastore.messages.CloseTransaction;
  35 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  36 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  37 import org.opendaylight.controller.cluster.datastore.messages.DataExists;
  38 import org.opendaylight.controller.cluster.datastore.messages.DataExistsReply;
  39 import org.opendaylight.controller.cluster.datastore.messages.DeleteData;
  40 import org.opendaylight.controller.cluster.datastore.messages.MergeData;
  41 import org.opendaylight.controller.cluster.datastore.messages.ReadData;
  42 import org.opendaylight.controller.cluster.datastore.messages.ReadDataReply;
  43 import org.opendaylight.controller.cluster.datastore.messages.ReadyTransaction;
  44 import org.opendaylight.controller.cluster.datastore.messages.ReadyTransactionReply;
  45 import org.opendaylight.controller.cluster.datastore.messages.SerializableMessage;
  46 import org.opendaylight.controller.cluster.datastore.messages.VersionedSerializableMessage;
  47 import org.opendaylight.controller.cluster.datastore.messages.WriteData;
  48 import org.opendaylight.controller.cluster.datastore.shardstrategy.ShardStrategyFactory;
  49 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
  50 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
  51 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadWriteTransaction;
  52 import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
  53 import org.opendaylight.yangtools.util.concurrent.MappingCheckedFuture;
  54 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  55 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  56 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  57 import org.slf4j.Logger;
  58 import org.slf4j.LoggerFactory;
  59 import scala.concurrent.Future;
  60 import scala.concurrent.Promise;
  61 import scala.concurrent.duration.FiniteDuration;
  62
  63 /**
  64  * TransactionProxy acts as a proxy for one or more transactions that were created on a remote shard
  65  * <p>
  66  * Creating a transaction on the consumer side will create one instance of a transaction proxy. If during
  67  * the transaction reads and writes are done on data that belongs to different shards then a separate transaction will
  68  * be created on each of those shards by the TransactionProxy
  69  *</p>
  70  * <p>
  71  * The TransactionProxy does not make any guarantees about atomicity or order in which the transactions on the various
  72  * shards will be executed.
  73  * </p>
  74  */
  75 public class TransactionProxy implements DOMStoreReadWriteTransaction {
  76
  77     public static enum TransactionType {
  78         READ_ONLY,
  79         WRITE_ONLY,
  80         READ_WRITE
  81     }
  82
  83     static final Mapper<Throwable, Throwable> SAME_FAILURE_TRANSFORMER =
  84                                                               new Mapper<Throwable, Throwable>() {
  85         @Override
  86         public Throwable apply(Throwable failure) {
  87             return failure;
  88         }
  89     };
  90
  91     private static final AtomicLong counter = new AtomicLong();
  92
  93     private static final Logger LOG = LoggerFactory.getLogger(TransactionProxy.class);
  94
  95     /**
  96      * Time interval in between transaction create retries.
  97      */
  98     private static final FiniteDuration CREATE_TX_TRY_INTERVAL =
  99             FiniteDuration.create(1, TimeUnit.SECONDS);
 100
 101     /**
 102      * Used to enqueue the PhantomReferences for read-only TransactionProxy instances. The
 103      * FinalizableReferenceQueue is safe to use statically in an OSGi environment as it uses some
 104      * trickery to clean up its internal thread when the bundle is unloaded.
 105      */
 106     private static final FinalizableReferenceQueue phantomReferenceQueue =
 107                                                                   new FinalizableReferenceQueue();
 108
 109     /**
 110      * This stores the TransactionProxyCleanupPhantomReference instances statically, This is
 111      * necessary because PhantomReferences need a hard reference so they're not garbage collected.
 112      * Once finalized, the TransactionProxyCleanupPhantomReference removes itself from this map
 113      * and thus becomes eligible for garbage collection.
 114      */
 115     private static final Map<TransactionProxyCleanupPhantomReference,
 116                              TransactionProxyCleanupPhantomReference> phantomReferenceCache =
 117                                                                         new ConcurrentHashMap<>();
 118
 119     /**
 120      * A PhantomReference that closes remote transactions for a TransactionProxy when it's
 121      * garbage collected. This is used for read-only transactions as they're not explicitly closed
 122      * by clients. So the only way to detect that a transaction is no longer in use and it's safe
 123      * to clean up is when it's garbage collected. It's inexact as to when an instance will be GC'ed
 124      * but TransactionProxy instances should generally be short-lived enough to avoid being moved
 125      * to the old generation space and thus should be cleaned up in a timely manner as the GC
 126      * runs on the young generation (eden, swap1...) space much more frequently.
 127      */
 128     private static class TransactionProxyCleanupPhantomReference
 129                                            extends FinalizablePhantomReference<TransactionProxy> {
 130
 131         private final List<ActorSelection> remoteTransactionActors;
 132         private final AtomicBoolean remoteTransactionActorsMB;
 133         private final ActorContext actorContext;
 134         private final TransactionIdentifier identifier;
 135
 136         protected TransactionProxyCleanupPhantomReference(TransactionProxy referent) {
 137             super(referent, phantomReferenceQueue);
 138
 139             // Note we need to cache the relevant fields from the TransactionProxy as we can't
 140             // have a hard reference to the TransactionProxy instance itself.
 141
 142             remoteTransactionActors = referent.remoteTransactionActors;
 143             remoteTransactionActorsMB = referent.remoteTransactionActorsMB;
 144             actorContext = referent.actorContext;
 145             identifier = referent.identifier;
 146         }
 147
 148         @Override
 149         public void finalizeReferent() {
 150             LOG.trace("Cleaning up {} Tx actors for TransactionProxy {}",
 151                     remoteTransactionActors.size(), identifier);
 152
 153             phantomReferenceCache.remove(this);
 154
 155             // Access the memory barrier volatile to ensure all previous updates to the
 156             // remoteTransactionActors list are visible to this thread.
 157
 158             if(remoteTransactionActorsMB.get()) {
 159                 for(ActorSelection actor : remoteTransactionActors) {
 160                     LOG.trace("Sending CloseTransaction to {}", actor);
 161                     actorContext.sendOperationAsync(actor, CloseTransaction.INSTANCE.toSerializable());
 162                 }
 163             }
 164         }
 165     }
 166
 167     /**
 168      * Stores the remote Tx actors for each requested data store path to be used by the
 169      * PhantomReference to close the remote Tx's. This is only used for read-only Tx's. The
 170      * remoteTransactionActorsMB volatile serves as a memory barrier to publish updates to the
 171      * remoteTransactionActors list so they will be visible to the thread accessing the
 172      * PhantomReference.
 173      */
 174     private List<ActorSelection> remoteTransactionActors;
 175     private AtomicBoolean remoteTransactionActorsMB;
 176
 177     /**
 178      * Stores the create transaction results per shard.
 179      */
 180     private final Map<String, TransactionFutureCallback> txFutureCallbackMap = new HashMap<>();
 181
 182     private final TransactionType transactionType;
 183     private final ActorContext actorContext;
 184     private final TransactionIdentifier identifier;
 185     private final String transactionChainId;
 186     private final SchemaContext schemaContext;
 187     private boolean inReadyState;
 188
 189     public TransactionProxy(ActorContext actorContext, TransactionType transactionType) {
 190         this(actorContext, transactionType, "");
 191     }
 192
 193     public TransactionProxy(ActorContext actorContext, TransactionType transactionType,
 194             String transactionChainId) {
 195         this.actorContext = Preconditions.checkNotNull(actorContext,
 196             "actorContext should not be null");
 197         this.transactionType = Preconditions.checkNotNull(transactionType,
 198             "transactionType should not be null");
 199         this.schemaContext = Preconditions.checkNotNull(actorContext.getSchemaContext(),
 200             "schemaContext should not be null");
 201         this.transactionChainId = transactionChainId;
 202
 203         String memberName = actorContext.getCurrentMemberName();
 204         if(memberName == null){
 205             memberName = "UNKNOWN-MEMBER";
 206         }
 207
 208         this.identifier = TransactionIdentifier.builder().memberName(memberName).counter(
 209             counter.getAndIncrement()).build();
 210
 211         if(transactionType == TransactionType.READ_ONLY) {
 212             // Read-only Tx's aren't explicitly closed by the client so we create a PhantomReference
 213             // to close the remote Tx's when this instance is no longer in use and is garbage
 214             // collected.
 215
 216             remoteTransactionActors = Lists.newArrayList();
 217             remoteTransactionActorsMB = new AtomicBoolean();
 218
 219             TransactionProxyCleanupPhantomReference cleanup =
 220                 new TransactionProxyCleanupPhantomReference(this);
 221             phantomReferenceCache.put(cleanup, cleanup);
 222         }
 223
 224         LOG.debug("Created txn {} of type {} on chain {}", identifier, transactionType, transactionChainId);
 225     }
 226
 227     @VisibleForTesting
 228     List<Future<Object>> getRecordedOperationFutures() {
 229         List<Future<Object>> recordedOperationFutures = Lists.newArrayList();
 230         for(TransactionFutureCallback txFutureCallback : txFutureCallbackMap.values()) {
 231             TransactionContext transactionContext = txFutureCallback.getTransactionContext();
 232             if(transactionContext != null) {
 233                 recordedOperationFutures.addAll(transactionContext.getRecordedOperationFutures());
 234             }
 235         }
 236
 237         return recordedOperationFutures;
 238     }
 239
 240     @VisibleForTesting
 241     boolean hasTransactionContext() {
 242         for(TransactionFutureCallback txFutureCallback : txFutureCallbackMap.values()) {
 243             TransactionContext transactionContext = txFutureCallback.getTransactionContext();
 244             if(transactionContext != null) {
 245                 return true;
 246             }
 247         }
 248
 249         return false;
 250     }
 251
 252     @Override
 253     public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> read(final YangInstanceIdentifier path) {
 254
 255         Preconditions.checkState(transactionType != TransactionType.WRITE_ONLY,
 256                 "Read operation on write-only transaction is not allowed");
 257
 258         LOG.debug("Tx {} read {}", identifier, path);
 259
 260         TransactionFutureCallback txFutureCallback = getOrCreateTxFutureCallback(path);
 261         return txFutureCallback.enqueueReadOperation(new ReadOperation<Optional<NormalizedNode<?, ?>>>() {
 262             @Override
 263             public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> invoke(
 264                     TransactionContext transactionContext) {
 265                 return transactionContext.readData(path);
 266             }
 267         });
 268     }
 269
 270     @Override
 271     public CheckedFuture<Boolean, ReadFailedException> exists(final YangInstanceIdentifier path) {
 272
 273         Preconditions.checkState(transactionType != TransactionType.WRITE_ONLY,
 274                 "Exists operation on write-only transaction is not allowed");
 275
 276         LOG.debug("Tx {} exists {}", identifier, path);
 277
 278         TransactionFutureCallback txFutureCallback = getOrCreateTxFutureCallback(path);
 279         return txFutureCallback.enqueueReadOperation(new ReadOperation<Boolean>() {
 280             @Override
 281             public CheckedFuture<Boolean, ReadFailedException> invoke(TransactionContext transactionContext) {
 282                 return transactionContext.dataExists(path);
 283             }
 284         });
 285     }
 286
 287
 288     private void checkModificationState() {
 289         Preconditions.checkState(transactionType != TransactionType.READ_ONLY,
 290                 "Modification operation on read-only transaction is not allowed");
 291         Preconditions.checkState(!inReadyState,
 292                 "Transaction is sealed - further modifications are not allowed");
 293     }
 294
 295     @Override
 296     public void write(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
 297
 298         checkModificationState();
 299
 300         LOG.debug("Tx {} write {}", identifier, path);
 301
 302         TransactionFutureCallback txFutureCallback = getOrCreateTxFutureCallback(path);
 303         txFutureCallback.enqueueModifyOperation(new TransactionOperation() {
 304             @Override
 305             public void invoke(TransactionContext transactionContext) {
 306                 transactionContext.writeData(path, data);
 307             }
 308         });
 309     }
 310
 311     @Override
 312     public void merge(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
 313
 314         checkModificationState();
 315
 316         LOG.debug("Tx {} merge {}", identifier, path);
 317
 318         TransactionFutureCallback txFutureCallback = getOrCreateTxFutureCallback(path);
 319         txFutureCallback.enqueueModifyOperation(new TransactionOperation() {
 320             @Override
 321             public void invoke(TransactionContext transactionContext) {
 322                 transactionContext.mergeData(path, data);
 323             }
 324         });
 325     }
 326
 327     @Override
 328     public void delete(final YangInstanceIdentifier path) {
 329
 330         checkModificationState();
 331
 332         LOG.debug("Tx {} delete {}", identifier, path);
 333
 334         TransactionFutureCallback txFutureCallback = getOrCreateTxFutureCallback(path);
 335         txFutureCallback.enqueueModifyOperation(new TransactionOperation() {
 336             @Override
 337             public void invoke(TransactionContext transactionContext) {
 338                 transactionContext.deleteData(path);
 339             }
 340         });
 341     }
 342
 343     @Override
 344     public DOMStoreThreePhaseCommitCohort ready() {
 345
 346         checkModificationState();
 347
 348         inReadyState = true;
 349
 350         LOG.debug("Tx {} Readying {} transactions for commit", identifier,
 351                     txFutureCallbackMap.size());
 352
 353         List<Future<ActorSelection>> cohortFutures = Lists.newArrayList();
 354
 355         for(TransactionFutureCallback txFutureCallback : txFutureCallbackMap.values()) {
 356
 357             LOG.debug("Tx {} Readying transaction for shard {} chain {}", identifier,
 358                         txFutureCallback.getShardName(), transactionChainId);
 359
 360             Future<ActorSelection> future = txFutureCallback.enqueueFutureOperation(new FutureOperation<ActorSelection>() {
 361                 @Override
 362                 public Future<ActorSelection> invoke(TransactionContext transactionContext) {
 363                     return transactionContext.readyTransaction();
 364                 }
 365             });
 366
 367             cohortFutures.add(future);
 368         }
 369
 370         onTransactionReady(cohortFutures);
 371
 372         return new ThreePhaseCommitCohortProxy(actorContext, cohortFutures,
 373                 identifier.toString());
 374     }
 375
 376     /**
 377      * Method for derived classes to be notified when the transaction has been readied.
 378      *
 379      * @param cohortFutures the cohort Futures for each shard transaction.
 380      */
 381     protected void onTransactionReady(List<Future<ActorSelection>> cohortFutures) {
 382     }
 383
 384     /**
 385      * Method called to send a CreateTransaction message to a shard.
 386      *
 387      * @param shard the shard actor to send to
 388      * @param serializedCreateMessage the serialized message to send
 389      * @return the response Future
 390      */
 391     protected Future<Object> sendCreateTransaction(ActorSelection shard,
 392             Object serializedCreateMessage) {
 393         return actorContext.executeOperationAsync(shard, serializedCreateMessage);
 394     }
 395
 396     @Override
 397     public Object getIdentifier() {
 398         return this.identifier;
 399     }
 400
 401     @Override
 402     public void close() {
 403         for (TransactionFutureCallback txFutureCallback : txFutureCallbackMap.values()) {
 404             txFutureCallback.enqueueModifyOperation(new TransactionOperation() {
 405                 @Override
 406                 public void invoke(TransactionContext transactionContext) {
 407                     transactionContext.closeTransaction();
 408                 }
 409             });
 410         }
 411
 412         txFutureCallbackMap.clear();
 413
 414         if(transactionType == TransactionType.READ_ONLY) {
 415             remoteTransactionActors.clear();
 416             remoteTransactionActorsMB.set(true);
 417         }
 418     }
 419
 420     private String shardNameFromIdentifier(YangInstanceIdentifier path){
 421         return ShardStrategyFactory.getStrategy(path).findShard(path);
 422     }
 423
 424     private TransactionFutureCallback getOrCreateTxFutureCallback(YangInstanceIdentifier path) {
 425         String shardName = shardNameFromIdentifier(path);
 426         TransactionFutureCallback txFutureCallback = txFutureCallbackMap.get(shardName);
 427         if(txFutureCallback == null) {
 428             Future<ActorSelection> findPrimaryFuture = actorContext.findPrimaryShardAsync(shardName);
 429
 430             final TransactionFutureCallback newTxFutureCallback =
 431                     new TransactionFutureCallback(shardName);
 432
 433             txFutureCallback = newTxFutureCallback;
 434             txFutureCallbackMap.put(shardName, txFutureCallback);
 435
 436             findPrimaryFuture.onComplete(new OnComplete<ActorSelection>() {
 437                 @Override
 438                 public void onComplete(Throwable failure, ActorSelection primaryShard) {
 439                     if(failure != null) {
 440                         newTxFutureCallback.onComplete(failure, null);
 441                     } else {
 442                         newTxFutureCallback.setPrimaryShard(primaryShard);
 443                     }
 444                 }
 445             }, actorContext.getActorSystem().dispatcher());
 446         }
 447
 448         return txFutureCallback;
 449     }
 450
 451     public String getTransactionChainId() {
 452         return transactionChainId;
 453     }
 454
 455     protected ActorContext getActorContext() {
 456         return actorContext;
 457     }
 458
 459     /**
 460      * Interfaces for transaction operations to be invoked later.
 461      */
 462     private static interface TransactionOperation {
 463         void invoke(TransactionContext transactionContext);
 464     }
 465
 466     /**
 467      * This interface returns a Guava Future
 468      */
 469     private static interface ReadOperation<T> {
 470         CheckedFuture<T, ReadFailedException> invoke(TransactionContext transactionContext);
 471     }
 472
 473     /**
 474      * This interface returns a Scala Future
 475      */
 476     private static interface FutureOperation<T> {
 477         Future<T> invoke(TransactionContext transactionContext);
 478     }
 479
 480     /**
 481      * Implements a Future OnComplete callback for a CreateTransaction message. This class handles
 482      * retries, up to a limit, if the shard doesn't have a leader yet. This is done by scheduling a
 483      * retry task after a short delay.
 484      * <p>
 485      * The end result from a completed CreateTransaction message is a TransactionContext that is
 486      * used to perform transaction operations. Transaction operations that occur before the
 487      * CreateTransaction completes are cache and executed once the CreateTransaction completes,
 488      * successfully or not.
 489      */
 490     private class TransactionFutureCallback extends OnComplete<Object> {
 491
 492         /**
 493          * The list of transaction operations to execute once the CreateTransaction completes.
 494          */
 495         @GuardedBy("txOperationsOnComplete")
 496         private final List<TransactionOperation> txOperationsOnComplete = Lists.newArrayList();
 497
 498         /**
 499          * The TransactionContext resulting from the CreateTransaction reply.
 500          */
 501         private volatile TransactionContext transactionContext;
 502
 503         /**
 504          * The target primary shard.
 505          */
 506         private volatile ActorSelection primaryShard;
 507
 508         private volatile int createTxTries = (int) (actorContext.getDatastoreContext().
 509                 getShardLeaderElectionTimeout().duration().toMillis() /
 510                 CREATE_TX_TRY_INTERVAL.toMillis());
 511
 512         private final String shardName;
 513
 514         TransactionFutureCallback(String shardName) {
 515             this.shardName = shardName;
 516         }
 517
 518         String getShardName() {
 519             return shardName;
 520         }
 521
 522         TransactionContext getTransactionContext() {
 523             return transactionContext;
 524         }
 525
 526
 527         /**
 528          * Sets the target primary shard and initiates a CreateTransaction try.
 529          */
 530         void setPrimaryShard(ActorSelection primaryShard) {
 531             LOG.debug("Tx {} Primary shard found - trying create transaction", identifier);
 532
 533             this.primaryShard = primaryShard;
 534             tryCreateTransaction();
 535         }
 536
 537         /**
 538          * Adds a TransactionOperation to be executed after the CreateTransaction completes.
 539          */
 540         void addTxOperationOnComplete(TransactionOperation operation) {
 541             synchronized(txOperationsOnComplete) {
 542                 if(transactionContext == null) {
 543                     LOG.debug("Tx {} Adding operation on complete {}", identifier);
 544
 545                     txOperationsOnComplete.add(operation);
 546                 } else {
 547                     operation.invoke(transactionContext);
 548                 }
 549             }
 550         }
 551
 552
 553         <T> Future<T> enqueueFutureOperation(final FutureOperation<T> op) {
 554
 555             Future<T> future;
 556
 557             if (transactionContext != null) {
 558                 future = op.invoke(transactionContext);
 559             } else {
 560                 // The shard Tx hasn't been created yet so add the Tx operation to the Tx Future
 561                 // callback to be executed after the Tx is created.
 562                 final Promise<T> promise = akka.dispatch.Futures.promise();
 563                 addTxOperationOnComplete(new TransactionOperation() {
 564                     @Override
 565                     public void invoke(TransactionContext transactionContext) {
 566                         promise.completeWith(op.invoke(transactionContext));
 567                     }
 568                 });
 569
 570                 future = promise.future();
 571             }
 572
 573             return future;
 574         }
 575
 576         <T> CheckedFuture<T, ReadFailedException> enqueueReadOperation(final ReadOperation<T> op) {
 577
 578             CheckedFuture<T, ReadFailedException> future;
 579
 580             if (transactionContext != null) {
 581                 future = op.invoke(transactionContext);
 582             } else {
 583                 // The shard Tx hasn't been created yet so add the Tx operation to the Tx Future
 584                 // callback to be executed after the Tx is created.
 585                 final SettableFuture<T> proxyFuture = SettableFuture.create();
 586                 addTxOperationOnComplete(new TransactionOperation() {
 587                     @Override
 588                     public void invoke(TransactionContext transactionContext) {
 589                         Futures.addCallback(op.invoke(transactionContext), new FutureCallback<T>() {
 590                             @Override
 591                             public void onSuccess(T data) {
 592                                 proxyFuture.set(data);
 593                             }
 594
 595                             @Override
 596                             public void onFailure(Throwable t) {
 597                                 proxyFuture.setException(t);
 598                             }
 599                         });
 600                     }
 601                 });
 602
 603                 future = MappingCheckedFuture.create(proxyFuture, ReadFailedException.MAPPER);
 604             }
 605
 606             return future;
 607         }
 608
 609         void enqueueModifyOperation(final TransactionOperation op) {
 610
 611             if (transactionContext != null) {
 612                 op.invoke(transactionContext);
 613             } else {
 614                 // The shard Tx hasn't been created yet so add the Tx operation to the Tx Future
 615                 // callback to be executed after the Tx is created.
 616                 addTxOperationOnComplete(op);
 617             }
 618         }
 619
 620         /**
 621          * Performs a CreateTransaction try async.
 622          */
 623         private void tryCreateTransaction() {
 624             Future<Object> createTxFuture = sendCreateTransaction(primaryShard,
 625                     new CreateTransaction(identifier.toString(),
 626                             TransactionProxy.this.transactionType.ordinal(),
 627                             getTransactionChainId()).toSerializable());
 628
 629             createTxFuture.onComplete(this, actorContext.getActorSystem().dispatcher());
 630         }
 631
 632         @Override
 633         public void onComplete(Throwable failure, Object response) {
 634             if(failure instanceof NoShardLeaderException) {
 635                 // There's no leader for the shard yet - schedule and try again, unless we're out
 636                 // of retries. Note: createTxTries is volatile as it may be written by different
 637                 // threads however not concurrently, therefore decrementing it non-atomically here
 638                 // is ok.
 639                 if(--createTxTries > 0) {
 640                     LOG.debug("Tx {} Shard {} has no leader yet - scheduling create Tx retry",
 641                             identifier, shardName);
 642
 643                     actorContext.getActorSystem().scheduler().scheduleOnce(CREATE_TX_TRY_INTERVAL,
 644                             new Runnable() {
 645                                 @Override
 646                                 public void run() {
 647                                     tryCreateTransaction();
 648                                 }
 649                             }, actorContext.getActorSystem().dispatcher());
 650                     return;
 651                 }
 652             }
 653
 654             // Create the TransactionContext from the response or failure and execute delayed
 655             // TransactionOperations. This entire section is done atomically (ie synchronized) with
 656             // respect to #addTxOperationOnComplete to handle timing issues and ensure no
 657             // TransactionOperation is missed and that they are processed in the order they occurred.
 658             synchronized(txOperationsOnComplete) {
 659                 // Store the new TransactionContext locally until we've completed invoking the
 660                 // TransactionOperations. This avoids thread timing issues which could cause
 661                 // out-of-order TransactionOperations. Eg, on a modification operation, if the
 662                 // TransactionContext is non-null, then we directly call the TransactionContext.
 663                 // However, at the same time, the code may be executing the cached
 664                 // TransactionOperations. So to avoid thus timing, we don't publish the
 665                 // TransactionContext until after we've executed all cached TransactionOperations.
 666                 TransactionContext localTransactionContext;
 667                 if(failure != null) {
 668                     LOG.debug("Tx {} Creating NoOpTransaction because of error: {}", identifier,
 669                             failure.getMessage());
 670
 671                     localTransactionContext = new NoOpTransactionContext(failure, identifier);
 672                 } else if (response.getClass().equals(CreateTransactionReply.SERIALIZABLE_CLASS)) {
 673                     localTransactionContext = createValidTransactionContext(
 674                             CreateTransactionReply.fromSerializable(response));
 675                 } else {
 676                     IllegalArgumentException exception = new IllegalArgumentException(String.format(
 677                         "Invalid reply type %s for CreateTransaction", response.getClass()));
 678
 679                     localTransactionContext = new NoOpTransactionContext(exception, identifier);
 680                 }
 681
 682                 for(TransactionOperation oper: txOperationsOnComplete) {
 683                     oper.invoke(localTransactionContext);
 684                 }
 685
 686                 txOperationsOnComplete.clear();
 687
 688                 // We're done invoking the TransactionOperations so we can now publish the
 689                 // TransactionContext.
 690                 transactionContext = localTransactionContext;
 691             }
 692         }
 693
 694         private TransactionContext createValidTransactionContext(CreateTransactionReply reply) {
 695             String transactionPath = reply.getTransactionPath();
 696
 697             LOG.debug("Tx {} Received transaction actor path {}", identifier, transactionPath);
 698
 699             ActorSelection transactionActor = actorContext.actorSelection(transactionPath);
 700
 701             if (transactionType == TransactionType.READ_ONLY) {
 702                 // Add the actor to the remoteTransactionActors list for access by the
 703                 // cleanup PhantonReference.
 704                 remoteTransactionActors.add(transactionActor);
 705
 706                 // Write to the memory barrier volatile to publish the above update to the
 707                 // remoteTransactionActors list for thread visibility.
 708                 remoteTransactionActorsMB.set(true);
 709             }
 710
 711             // TxActor is always created where the leader of the shard is.
 712             // Check if TxActor is created in the same node
 713             boolean isTxActorLocal = actorContext.isPathLocal(transactionPath);
 714
 715             return new TransactionContextImpl(transactionPath, transactionActor, identifier,
 716                 actorContext, schemaContext, isTxActorLocal, reply.getVersion());
 717         }
 718     }
 719
 720     private interface TransactionContext {
 721         void closeTransaction();
 722
 723         Future<ActorSelection> readyTransaction();
 724
 725         void writeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data);
 726
 727         void deleteData(YangInstanceIdentifier path);
 728
 729         void mergeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data);
 730
 731         CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> readData(
 732                 final YangInstanceIdentifier path);
 733
 734         CheckedFuture<Boolean, ReadFailedException> dataExists(YangInstanceIdentifier path);
 735
 736         List<Future<Object>> getRecordedOperationFutures();
 737     }
 738
 739     private static abstract class AbstractTransactionContext implements TransactionContext {
 740
 741         protected final TransactionIdentifier identifier;
 742         protected final List<Future<Object>> recordedOperationFutures = Lists.newArrayList();
 743
 744         AbstractTransactionContext(TransactionIdentifier identifier) {
 745             this.identifier = identifier;
 746         }
 747
 748         @Override
 749         public List<Future<Object>> getRecordedOperationFutures() {
 750             return recordedOperationFutures;
 751         }
 752     }
 753
 754     private static class TransactionContextImpl extends AbstractTransactionContext {
 755         private final Logger LOG = LoggerFactory.getLogger(TransactionContextImpl.class);
 756
 757         private final ActorContext actorContext;
 758         private final SchemaContext schemaContext;
 759         private final String transactionPath;
 760         private final ActorSelection actor;
 761         private final boolean isTxActorLocal;
 762         private final short remoteTransactionVersion;
 763
 764         private TransactionContextImpl(String transactionPath, ActorSelection actor, TransactionIdentifier identifier,
 765                 ActorContext actorContext, SchemaContext schemaContext,
 766                 boolean isTxActorLocal, short remoteTransactionVersion) {
 767             super(identifier);
 768             this.transactionPath = transactionPath;
 769             this.actor = actor;
 770             this.actorContext = actorContext;
 771             this.schemaContext = schemaContext;
 772             this.isTxActorLocal = isTxActorLocal;
 773             this.remoteTransactionVersion = remoteTransactionVersion;
 774         }
 775
 776         private ActorSelection getActor() {
 777             return actor;
 778         }
 779
 780         private Future<Object> executeOperationAsync(SerializableMessage msg) {
 781             return actorContext.executeOperationAsync(getActor(), isTxActorLocal ? msg : msg.toSerializable());
 782         }
 783
 784         private Future<Object> executeOperationAsync(VersionedSerializableMessage msg) {
 785             return actorContext.executeOperationAsync(getActor(), isTxActorLocal ? msg :
 786                 msg.toSerializable(remoteTransactionVersion));
 787         }
 788
 789         @Override
 790         public void closeTransaction() {
 791             LOG.debug("Tx {} closeTransaction called", identifier);
 792
 793             actorContext.sendOperationAsync(getActor(), CloseTransaction.INSTANCE.toSerializable());
 794         }
 795
 796         @Override
 797         public Future<ActorSelection> readyTransaction() {
 798             LOG.debug("Tx {} readyTransaction called with {} previous recorded operations pending",
 799                     identifier, recordedOperationFutures.size());
 800
 801             // Send the ReadyTransaction message to the Tx actor.
 802
 803             final Future<Object> replyFuture = executeOperationAsync(ReadyTransaction.INSTANCE);
 804
 805             // Combine all the previously recorded put/merge/delete operation reply Futures and the
 806             // ReadyTransactionReply Future into one Future. If any one fails then the combined
 807             // Future will fail. We need all prior operations and the ready operation to succeed
 808             // in order to attempt commit.
 809
 810             List<Future<Object>> futureList =
 811                     Lists.newArrayListWithCapacity(recordedOperationFutures.size() + 1);
 812             futureList.addAll(recordedOperationFutures);
 813             futureList.add(replyFuture);
 814
 815             Future<Iterable<Object>> combinedFutures = akka.dispatch.Futures.sequence(futureList,
 816                     actorContext.getActorSystem().dispatcher());
 817
 818             // Transform the combined Future into a Future that returns the cohort actor path from
 819             // the ReadyTransactionReply. That's the end result of the ready operation.
 820
 821             return combinedFutures.transform(new Mapper<Iterable<Object>, ActorSelection>() {
 822                 @Override
 823                 public ActorSelection checkedApply(Iterable<Object> notUsed) {
 824                     LOG.debug("Tx {} readyTransaction: pending recorded operations succeeded",
 825                             identifier);
 826
 827                     // At this point all the Futures succeeded and we need to extract the cohort
 828                     // actor path from the ReadyTransactionReply. For the recorded operations, they
 829                     // don't return any data so we're only interested that they completed
 830                     // successfully. We could be paranoid and verify the correct reply types but
 831                     // that really should never happen so it's not worth the overhead of
 832                     // de-serializing each reply.
 833
 834                     // Note the Future get call here won't block as it's complete.
 835                     Object serializedReadyReply = replyFuture.value().get().get();
 836                     if (serializedReadyReply instanceof ReadyTransactionReply) {
 837                         return actorContext.actorSelection(((ReadyTransactionReply)serializedReadyReply).getCohortPath());
 838
 839                     } else if(serializedReadyReply.getClass().equals(ReadyTransactionReply.SERIALIZABLE_CLASS)) {
 840                         ReadyTransactionReply reply = ReadyTransactionReply.fromSerializable(serializedReadyReply);
 841                         String cohortPath = reply.getCohortPath();
 842
 843                         // In Helium we used to return the local path of the actor which represented
 844                         // a remote ThreePhaseCommitCohort. The local path would then be converted to
 845                         // a remote path using this resolvePath method. To maintain compatibility with
 846                         // a Helium node we need to continue to do this conversion.
 847                         // At some point in the future when upgrades from Helium are not supported
 848                         // we could remove this code to resolvePath and just use the cohortPath as the
 849                         // resolved cohortPath
 850                         if(TransactionContextImpl.this.remoteTransactionVersion <
 851                                 DataStoreVersions.HELIUM_1_VERSION) {
 852                             cohortPath = actorContext.resolvePath(transactionPath, cohortPath);
 853                         }
 854
 855                         return actorContext.actorSelection(cohortPath);
 856
 857                     } else {
 858                         // Throwing an exception here will fail the Future.
 859                         throw new IllegalArgumentException(String.format("Invalid reply type {}",
 860                                 serializedReadyReply.getClass()));
 861                     }
 862                 }
 863             }, SAME_FAILURE_TRANSFORMER, actorContext.getActorSystem().dispatcher());
 864         }
 865
 866         @Override
 867         public void deleteData(YangInstanceIdentifier path) {
 868             LOG.debug("Tx {} deleteData called path = {}", identifier, path);
 869
 870             recordedOperationFutures.add(executeOperationAsync(new DeleteData(path)));
 871         }
 872
 873         @Override
 874         public void mergeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data) {
 875             LOG.debug("Tx {} mergeData called path = {}", identifier, path);
 876
 877             recordedOperationFutures.add(executeOperationAsync(new MergeData(path, data)));
 878         }
 879
 880         @Override
 881         public void writeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data) {
 882             LOG.debug("Tx {} writeData called path = {}", identifier, path);
 883
 884             recordedOperationFutures.add(executeOperationAsync(new WriteData(path, data)));
 885         }
 886
 887         @Override
 888         public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> readData(
 889                 final YangInstanceIdentifier path) {
 890
 891             LOG.debug("Tx {} readData called path = {}", identifier, path);
 892
 893             final SettableFuture<Optional<NormalizedNode<?, ?>>> returnFuture = SettableFuture.create();
 894
 895             // If there were any previous recorded put/merge/delete operation reply Futures then we
 896             // must wait for them to successfully complete. This is necessary to honor the read
 897             // uncommitted semantics of the public API contract. If any one fails then fail the read.
 898
 899             if(recordedOperationFutures.isEmpty()) {
 900                 finishReadData(path, returnFuture);
 901             } else {
 902                 LOG.debug("Tx {} readData: verifying {} previous recorded operations",
 903                         identifier, recordedOperationFutures.size());
 904
 905                 // Note: we make a copy of recordedOperationFutures to be on the safe side in case
 906                 // Futures#sequence accesses the passed List on a different thread, as
 907                 // recordedOperationFutures is not synchronized.
 908
 909                 Future<Iterable<Object>> combinedFutures = akka.dispatch.Futures.sequence(
 910                         Lists.newArrayList(recordedOperationFutures),
 911                         actorContext.getActorSystem().dispatcher());
 912
 913                 OnComplete<Iterable<Object>> onComplete = new OnComplete<Iterable<Object>>() {
 914                     @Override
 915                     public void onComplete(Throwable failure, Iterable<Object> notUsed)
 916                             throws Throwable {
 917                         if(failure != null) {
 918                             LOG.debug("Tx {} readData: a recorded operation failed: {}",
 919                                     identifier, failure);
 920                             returnFuture.setException(new ReadFailedException(
 921                                     "The read could not be performed because a previous put, merge,"
 922                                     + "or delete operation failed", failure));
 923                         } else {
 924                             finishReadData(path, returnFuture);
 925                         }
 926                     }
 927                 };
 928
 929                 combinedFutures.onComplete(onComplete, actorContext.getActorSystem().dispatcher());
 930             }
 931
 932             return MappingCheckedFuture.create(returnFuture, ReadFailedException.MAPPER);
 933         }
 934
 935         private void finishReadData(final YangInstanceIdentifier path,
 936                 final SettableFuture<Optional<NormalizedNode<?, ?>>> returnFuture) {
 937
 938             LOG.debug("Tx {} finishReadData called path = {}", identifier, path);
 939
 940             OnComplete<Object> onComplete = new OnComplete<Object>() {
 941                 @Override
 942                 public void onComplete(Throwable failure, Object readResponse) throws Throwable {
 943                     if(failure != null) {
 944                         LOG.debug("Tx {} read operation failed: {}", identifier, failure);
 945                         returnFuture.setException(new ReadFailedException(
 946                                 "Error reading data for path " + path, failure));
 947
 948                     } else {
 949                         LOG.debug("Tx {} read operation succeeded", identifier, failure);
 950
 951                         if (readResponse instanceof ReadDataReply) {
 952                             ReadDataReply reply = (ReadDataReply) readResponse;
 953                             returnFuture.set(Optional.<NormalizedNode<?, ?>>fromNullable(reply.getNormalizedNode()));
 954
 955                         } else if (ReadDataReply.isSerializedType(readResponse)) {
 956                             ReadDataReply reply = ReadDataReply.fromSerializable(readResponse);
 957                             returnFuture.set(Optional.<NormalizedNode<?, ?>>fromNullable(reply.getNormalizedNode()));
 958
 959                         } else {
 960                             returnFuture.setException(new ReadFailedException(
 961                                 "Invalid response reading data for path " + path));
 962                         }
 963                     }
 964                 }
 965             };
 966
 967             Future<Object> readFuture = executeOperationAsync(new ReadData(path));
 968
 969             readFuture.onComplete(onComplete, actorContext.getActorSystem().dispatcher());
 970         }
 971
 972         @Override
 973         public CheckedFuture<Boolean, ReadFailedException> dataExists(
 974                 final YangInstanceIdentifier path) {
 975
 976             LOG.debug("Tx {} dataExists called path = {}", identifier, path);
 977
 978             final SettableFuture<Boolean> returnFuture = SettableFuture.create();
 979
 980             // If there were any previous recorded put/merge/delete operation reply Futures then we
 981             // must wait for them to successfully complete. This is necessary to honor the read
 982             // uncommitted semantics of the public API contract. If any one fails then fail this
 983             // request.
 984
 985             if(recordedOperationFutures.isEmpty()) {
 986                 finishDataExists(path, returnFuture);
 987             } else {
 988                 LOG.debug("Tx {} dataExists: verifying {} previous recorded operations",
 989                         identifier, recordedOperationFutures.size());
 990
 991                 // Note: we make a copy of recordedOperationFutures to be on the safe side in case
 992                 // Futures#sequence accesses the passed List on a different thread, as
 993                 // recordedOperationFutures is not synchronized.
 994
 995                 Future<Iterable<Object>> combinedFutures = akka.dispatch.Futures.sequence(
 996                         Lists.newArrayList(recordedOperationFutures),
 997                         actorContext.getActorSystem().dispatcher());
 998                 OnComplete<Iterable<Object>> onComplete = new OnComplete<Iterable<Object>>() {
 999                     @Override
1000                     public void onComplete(Throwable failure, Iterable<Object> notUsed)
1001                             throws Throwable {
1002                         if(failure != null) {
1003                             LOG.debug("Tx {} dataExists: a recorded operation failed: {}",
1004                                     identifier, failure);
1005                             returnFuture.setException(new ReadFailedException(
1006                                     "The data exists could not be performed because a previous "
1007                                     + "put, merge, or delete operation failed", failure));
1008                         } else {
1009                             finishDataExists(path, returnFuture);
1010                         }
1011                     }
1012                 };
1013
1014                 combinedFutures.onComplete(onComplete, actorContext.getActorSystem().dispatcher());
1015             }
1016
1017             return MappingCheckedFuture.create(returnFuture, ReadFailedException.MAPPER);
1018         }
1019
1020         private void finishDataExists(final YangInstanceIdentifier path,
1021                 final SettableFuture<Boolean> returnFuture) {
1022
1023             LOG.debug("Tx {} finishDataExists called path = {}", identifier, path);
1024
1025             OnComplete<Object> onComplete = new OnComplete<Object>() {
1026                 @Override
1027                 public void onComplete(Throwable failure, Object response) throws Throwable {
1028                     if(failure != null) {
1029                         LOG.debug("Tx {} dataExists operation failed: {}", identifier, failure);
1030                         returnFuture.setException(new ReadFailedException(
1031                                 "Error checking data exists for path " + path, failure));
1032                     } else {
1033                         LOG.debug("Tx {} dataExists operation succeeded", identifier, failure);
1034
1035                         if (response instanceof DataExistsReply) {
1036                             returnFuture.set(Boolean.valueOf(((DataExistsReply) response).exists()));
1037
1038                         } else if (response.getClass().equals(DataExistsReply.SERIALIZABLE_CLASS)) {
1039                             returnFuture.set(Boolean.valueOf(DataExistsReply.fromSerializable(response).exists()));
1040
1041                         } else {
1042                             returnFuture.setException(new ReadFailedException(
1043                                     "Invalid response checking exists for path " + path));
1044                         }
1045                     }
1046                 }
1047             };
1048
1049             Future<Object> future = executeOperationAsync(new DataExists(path));
1050
1051             future.onComplete(onComplete, actorContext.getActorSystem().dispatcher());
1052         }
1053     }
1054
1055     private static class NoOpTransactionContext extends AbstractTransactionContext {
1056
1057         private final Logger LOG = LoggerFactory.getLogger(NoOpTransactionContext.class);
1058
1059         private final Throwable failure;
1060
1061         public NoOpTransactionContext(Throwable failure, TransactionIdentifier identifier){
1062             super(identifier);
1063             this.failure = failure;
1064         }
1065
1066         @Override
1067         public void closeTransaction() {
1068             LOG.debug("NoOpTransactionContext {} closeTransaction called", identifier);
1069         }
1070
1071         @Override
1072         public Future<ActorSelection> readyTransaction() {
1073             LOG.debug("Tx {} readyTransaction called", identifier);
1074             return akka.dispatch.Futures.failed(failure);
1075         }
1076
1077         @Override
1078         public void deleteData(YangInstanceIdentifier path) {
1079             LOG.debug("Tx {} deleteData called path = {}", identifier, path);
1080         }
1081
1082         @Override
1083         public void mergeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data) {
1084             LOG.debug("Tx {} mergeData called path = {}", identifier, path);
1085         }
1086
1087         @Override
1088         public void writeData(YangInstanceIdentifier path, NormalizedNode<?, ?> data) {
1089             LOG.debug("Tx {} writeData called path = {}", identifier, path);
1090         }
1091
1092         @Override
1093         public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> readData(
1094                 YangInstanceIdentifier path) {
1095             LOG.debug("Tx {} readData called path = {}", identifier, path);
1096             return Futures.immediateFailedCheckedFuture(new ReadFailedException(
1097                     "Error reading data for path " + path, failure));
1098         }
1099
1100         @Override
1101         public CheckedFuture<Boolean, ReadFailedException> dataExists(
1102                 YangInstanceIdentifier path) {
1103             LOG.debug("Tx {} dataExists called path = {}", identifier, path);
1104             return Futures.immediateFailedCheckedFuture(new ReadFailedException(
1105                     "Error checking exists for path " + path, failure));
1106         }
1107     }
1108 }