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