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

   1 /*
   2  * Copyright (c) 2014 Brocade Communications Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.controller.cluster.datastore;
   9
  10 import akka.actor.ActorRef;
  11 import akka.actor.Status;
  12 import akka.serialization.Serialization;
  13 import com.google.common.annotations.VisibleForTesting;
  14 import com.google.common.base.Preconditions;
  15 import com.google.common.base.Stopwatch;
  16 import java.util.HashMap;
  17 import java.util.Iterator;
  18 import java.util.LinkedList;
  19 import java.util.Map;
  20 import java.util.Queue;
  21 import java.util.concurrent.ExecutionException;
  22 import java.util.concurrent.TimeUnit;
  23 import org.opendaylight.controller.cluster.datastore.compat.BackwardsCompatibleThreePhaseCommitCohort;
  24 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  25 import org.opendaylight.controller.cluster.datastore.messages.BatchedModificationsReply;
  26 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransactionReply;
  27 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
  28 import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
  29 import org.opendaylight.controller.cluster.datastore.messages.ReadyTransactionReply;
  30 import org.opendaylight.controller.cluster.datastore.modification.Modification;
  31 import org.opendaylight.controller.cluster.datastore.modification.MutableCompositeModification;
  32 import org.opendaylight.controller.md.sal.common.api.data.TransactionCommitFailedException;
  33 import org.slf4j.Logger;
  34
  35 /**
  36  * Coordinates commits for a shard ensuring only one concurrent 3-phase commit.
  37  *
  38  * @author Thomas Pantelis
  39  */
  40 class ShardCommitCoordinator {
  41
  42     // Interface hook for unit tests to replace or decorate the DOMStoreThreePhaseCommitCohorts.
  43     public interface CohortDecorator {
  44         ShardDataTreeCohort decorate(String transactionID, ShardDataTreeCohort actual);
  45     }
  46
  47     private final Map<String, CohortEntry> cohortCache = new HashMap<>();
  48
  49     private CohortEntry currentCohortEntry;
  50
  51     private final ShardDataTree dataTree;
  52
  53     // We use a LinkedList here to avoid synchronization overhead with concurrent queue impls
  54     // since this should only be accessed on the shard's dispatcher.
  55     private final Queue<CohortEntry> queuedCohortEntries = new LinkedList<>();
  56
  57     private int queueCapacity;
  58
  59     private final Logger log;
  60
  61     private final String name;
  62
  63     private final long cacheExpiryTimeoutInMillis;
  64
  65     // This is a hook for unit tests to replace or decorate the DOMStoreThreePhaseCommitCohorts.
  66     private CohortDecorator cohortDecorator;
  67
  68     private ReadyTransactionReply readyTransactionReply;
  69
  70     ShardCommitCoordinator(ShardDataTree dataTree,
  71             long cacheExpiryTimeoutInMillis, int queueCapacity, ActorRef shardActor, Logger log, String name) {
  72
  73         this.queueCapacity = queueCapacity;
  74         this.log = log;
  75         this.name = name;
  76         this.dataTree = Preconditions.checkNotNull(dataTree);
  77         this.cacheExpiryTimeoutInMillis = cacheExpiryTimeoutInMillis;
  78     }
  79
  80     void setQueueCapacity(int queueCapacity) {
  81         this.queueCapacity = queueCapacity;
  82     }
  83
  84     private ReadyTransactionReply readyTransactionReply(Shard shard) {
  85         if(readyTransactionReply == null) {
  86             readyTransactionReply = new ReadyTransactionReply(Serialization.serializedActorPath(shard.self()));
  87         }
  88
  89         return readyTransactionReply;
  90     }
  91
  92     private boolean queueCohortEntry(CohortEntry cohortEntry, ActorRef sender, Shard shard) {
  93         if(queuedCohortEntries.size() < queueCapacity) {
  94             queuedCohortEntries.offer(cohortEntry);
  95             return true;
  96         } else {
  97             cohortCache.remove(cohortEntry.getTransactionID());
  98
  99             RuntimeException ex = new RuntimeException(
 100                     String.format("%s: Could not enqueue transaction %s - the maximum commit queue"+
 101                                   " capacity %d has been reached.",
 102                                   name, cohortEntry.getTransactionID(), queueCapacity));
 103             log.error(ex.getMessage());
 104             sender.tell(new Status.Failure(ex), shard.self());
 105             return false;
 106         }
 107     }
 108
 109     /**
 110      * This method is called to ready a transaction that was prepared by ShardTransaction actor. It caches
 111      * the prepared cohort entry for the given transactions ID in preparation for the subsequent 3-phase commit.
 112      *
 113      * @param ready the ForwardedReadyTransaction message to process
 114      * @param sender the sender of the message
 115      * @param shard the transaction's shard actor
 116      */
 117     void handleForwardedReadyTransaction(ForwardedReadyTransaction ready, ActorRef sender, Shard shard) {
 118         log.debug("{}: Readying transaction {}, client version {}", name,
 119                 ready.getTransactionID(), ready.getTxnClientVersion());
 120
 121         CohortEntry cohortEntry = new CohortEntry(ready.getTransactionID(), ready.getCohort(),
 122                 (MutableCompositeModification) ready.getModification());
 123         cohortCache.put(ready.getTransactionID(), cohortEntry);
 124
 125         if(!queueCohortEntry(cohortEntry, sender, shard)) {
 126             return;
 127         }
 128
 129         if(ready.getTxnClientVersion() < DataStoreVersions.LITHIUM_VERSION) {
 130             // Return our actor path as we'll handle the three phase commit except if the Tx client
 131             // version < Helium-1 version which means the Tx was initiated by a base Helium version node.
 132             // In that case, the subsequent 3-phase commit messages won't contain the transactionId so to
 133             // maintain backwards compatibility, we create a separate cohort actor to provide the compatible behavior.
 134             ActorRef replyActorPath = shard.self();
 135             if(ready.getTxnClientVersion() < DataStoreVersions.HELIUM_1_VERSION) {
 136                 log.debug("{}: Creating BackwardsCompatibleThreePhaseCommitCohort", name);
 137                 replyActorPath = shard.getContext().actorOf(BackwardsCompatibleThreePhaseCommitCohort.props(
 138                         ready.getTransactionID()));
 139             }
 140
 141             ReadyTransactionReply readyTransactionReply =
 142                     new ReadyTransactionReply(Serialization.serializedActorPath(replyActorPath),
 143                             ready.getTxnClientVersion());
 144             sender.tell(ready.isReturnSerialized() ? readyTransactionReply.toSerializable() :
 145                 readyTransactionReply, shard.self());
 146         } else {
 147             if(ready.isDoImmediateCommit()) {
 148                 cohortEntry.setDoImmediateCommit(true);
 149                 cohortEntry.setReplySender(sender);
 150                 cohortEntry.setShard(shard);
 151                 handleCanCommit(cohortEntry);
 152             } else {
 153                 // The caller does not want immediate commit - the 3-phase commit will be coordinated by the
 154                 // front-end so send back a ReadyTransactionReply with our actor path.
 155                 sender.tell(readyTransactionReply(shard), shard.self());
 156             }
 157         }
 158     }
 159
 160     /**
 161      * This method handles a BatchedModifications message for a transaction being prepared directly on the
 162      * Shard actor instead of via a ShardTransaction actor. If there's no currently cached
 163      * DOMStoreWriteTransaction, one is created. The batched modifications are applied to the write Tx. If
 164      * the BatchedModifications is ready to commit then a DOMStoreThreePhaseCommitCohort is created.
 165      *
 166      * @param batched the BatchedModifications message to process
 167      * @param sender the sender of the message
 168      * @param shard the transaction's shard actor
 169      */
 170     void handleBatchedModifications(BatchedModifications batched, ActorRef sender, Shard shard) {
 171         CohortEntry cohortEntry = cohortCache.get(batched.getTransactionID());
 172         if(cohortEntry == null) {
 173             cohortEntry = new CohortEntry(batched.getTransactionID(),
 174                     dataTree.newReadWriteTransaction(batched.getTransactionID(),
 175                         batched.getTransactionChainID()));
 176             cohortCache.put(batched.getTransactionID(), cohortEntry);
 177         }
 178
 179         if(log.isDebugEnabled()) {
 180             log.debug("{}: Applying {} batched modifications for Tx {}", name,
 181                     batched.getModifications().size(), batched.getTransactionID());
 182         }
 183
 184         cohortEntry.applyModifications(batched.getModifications());
 185
 186         if(batched.isReady()) {
 187             if(cohortEntry.getLastBatchedModificationsException() != null) {
 188                 cohortCache.remove(cohortEntry.getTransactionID());
 189                 throw cohortEntry.getLastBatchedModificationsException();
 190             }
 191
 192             if(cohortEntry.getTotalBatchedModificationsReceived() != batched.getTotalMessagesSent()) {
 193                 cohortCache.remove(cohortEntry.getTransactionID());
 194                 throw new IllegalStateException(String.format(
 195                         "The total number of batched messages received %d does not match the number sent %d",
 196                         cohortEntry.getTotalBatchedModificationsReceived(), batched.getTotalMessagesSent()));
 197             }
 198
 199             if(!queueCohortEntry(cohortEntry, sender, shard)) {
 200                 return;
 201             }
 202
 203             if(log.isDebugEnabled()) {
 204                 log.debug("{}: Readying Tx {}, client version {}", name,
 205                         batched.getTransactionID(), batched.getVersion());
 206             }
 207
 208             cohortEntry.ready(cohortDecorator, batched.isDoCommitOnReady());
 209
 210             if(batched.isDoCommitOnReady()) {
 211                 cohortEntry.setReplySender(sender);
 212                 cohortEntry.setShard(shard);
 213                 handleCanCommit(cohortEntry);
 214             } else {
 215                 sender.tell(readyTransactionReply(shard), shard.self());
 216             }
 217         } else {
 218             sender.tell(new BatchedModificationsReply(batched.getModifications().size()), shard.self());
 219         }
 220     }
 221
 222     /**
 223      * This method handles {@link ReadyLocalTransaction} message. All transaction modifications have
 224      * been prepared beforehand by the sender and we just need to drive them through into the dataTree.
 225      *
 226      * @param message the ReadyLocalTransaction message to process
 227      * @param sender the sender of the message
 228      * @param shard the transaction's shard actor
 229      */
 230     void handleReadyLocalTransaction(ReadyLocalTransaction message, ActorRef sender, Shard shard) {
 231         final ShardDataTreeCohort cohort = new SimpleShardDataTreeCohort(dataTree, message.getModification(),
 232                 message.getTransactionID());
 233         final CohortEntry cohortEntry = new CohortEntry(message.getTransactionID(), cohort);
 234         cohortCache.put(message.getTransactionID(), cohortEntry);
 235         cohortEntry.setDoImmediateCommit(message.isDoCommitOnReady());
 236
 237         if(!queueCohortEntry(cohortEntry, sender, shard)) {
 238             return;
 239         }
 240
 241         log.debug("{}: Applying local modifications for Tx {}", name, message.getTransactionID());
 242
 243         if (message.isDoCommitOnReady()) {
 244             cohortEntry.setReplySender(sender);
 245             cohortEntry.setShard(shard);
 246             handleCanCommit(cohortEntry);
 247         } else {
 248             sender.tell(readyTransactionReply(shard), shard.self());
 249         }
 250     }
 251
 252     private void handleCanCommit(CohortEntry cohortEntry) {
 253         String transactionID = cohortEntry.getTransactionID();
 254
 255         cohortEntry.updateLastAccessTime();
 256
 257         if(currentCohortEntry != null) {
 258             // There's already a Tx commit in progress so we can't process this entry yet - but it's in the
 259             // queue and will get processed after all prior entries complete.
 260
 261             if(log.isDebugEnabled()) {
 262                 log.debug("{}: Commit for Tx {} already in progress - skipping canCommit for {} for now",
 263                         name, currentCohortEntry.getTransactionID(), transactionID);
 264             }
 265
 266             return;
 267         }
 268
 269         // No Tx commit currently in progress - check if this entry is the next one in the queue, If so make
 270         // it the current entry and proceed with canCommit.
 271         // Purposely checking reference equality here.
 272         if(queuedCohortEntries.peek() == cohortEntry) {
 273             currentCohortEntry = queuedCohortEntries.poll();
 274             doCanCommit(currentCohortEntry);
 275         } else {
 276             if(log.isDebugEnabled()) {
 277                 log.debug("{}: Tx {} is the next pending canCommit - skipping {} for now",
 278                         name, queuedCohortEntries.peek().getTransactionID(), transactionID);
 279             }
 280         }
 281     }
 282
 283     /**
 284      * This method handles the canCommit phase for a transaction.
 285      *
 286      * @param transactionID the ID of the transaction to canCommit
 287      * @param sender the actor to which to send the response
 288      * @param shard the transaction's shard actor
 289      */
 290     void handleCanCommit(String transactionID, final ActorRef sender, final Shard shard) {
 291         // Lookup the cohort entry that was cached previously (or should have been) by
 292         // transactionReady (via the ForwardedReadyTransaction message).
 293         final CohortEntry cohortEntry = cohortCache.get(transactionID);
 294         if(cohortEntry == null) {
 295             // Either canCommit was invoked before ready(shouldn't happen)  or a long time passed
 296             // between canCommit and ready and the entry was expired from the cache.
 297             IllegalStateException ex = new IllegalStateException(
 298                     String.format("%s: No cohort entry found for transaction %s", name, transactionID));
 299             log.error(ex.getMessage());
 300             sender.tell(new Status.Failure(ex), shard.self());
 301             return;
 302         }
 303
 304         cohortEntry.setReplySender(sender);
 305         cohortEntry.setShard(shard);
 306
 307         handleCanCommit(cohortEntry);
 308     }
 309
 310     private void doCanCommit(final CohortEntry cohortEntry) {
 311         boolean canCommit = false;
 312         try {
 313             // We block on the future here so we don't have to worry about possibly accessing our
 314             // state on a different thread outside of our dispatcher. Also, the data store
 315             // currently uses a same thread executor anyway.
 316             canCommit = cohortEntry.getCohort().canCommit().get();
 317
 318             log.debug("{}: canCommit for {}: {}", name, cohortEntry.getTransactionID(), canCommit);
 319
 320             if(cohortEntry.isDoImmediateCommit()) {
 321                 if(canCommit) {
 322                     doCommit(cohortEntry);
 323                 } else {
 324                     cohortEntry.getReplySender().tell(new Status.Failure(new TransactionCommitFailedException(
 325                                 "Can Commit failed, no detailed cause available.")), cohortEntry.getShard().self());
 326                 }
 327             } else {
 328                 cohortEntry.getReplySender().tell(
 329                         canCommit ? CanCommitTransactionReply.YES.toSerializable() :
 330                             CanCommitTransactionReply.NO.toSerializable(), cohortEntry.getShard().self());
 331             }
 332         } catch (Exception e) {
 333             log.debug("{}: An exception occurred during canCommit", name, e);
 334
 335             Throwable failure = e;
 336             if(e instanceof ExecutionException) {
 337                 failure = e.getCause();
 338             }
 339
 340             cohortEntry.getReplySender().tell(new Status.Failure(failure), cohortEntry.getShard().self());
 341         } finally {
 342             if(!canCommit) {
 343                 // Remove the entry from the cache now.
 344                 currentTransactionComplete(cohortEntry.getTransactionID(), true);
 345             }
 346         }
 347     }
 348
 349     private boolean doCommit(CohortEntry cohortEntry) {
 350         log.debug("{}: Committing transaction {}", name, cohortEntry.getTransactionID());
 351
 352         boolean success = false;
 353
 354         // We perform the preCommit phase here atomically with the commit phase. This is an
 355         // optimization to eliminate the overhead of an extra preCommit message. We lose front-end
 356         // coordination of preCommit across shards in case of failure but preCommit should not
 357         // normally fail since we ensure only one concurrent 3-phase commit.
 358
 359         try {
 360             // We block on the future here so we don't have to worry about possibly accessing our
 361             // state on a different thread outside of our dispatcher. Also, the data store
 362             // currently uses a same thread executor anyway.
 363             cohortEntry.getCohort().preCommit().get();
 364
 365             cohortEntry.getShard().continueCommit(cohortEntry);
 366
 367             cohortEntry.updateLastAccessTime();
 368
 369             success = true;
 370         } catch (Exception e) {
 371             log.error("{} An exception occurred while preCommitting transaction {}",
 372                     name, cohortEntry.getTransactionID(), e);
 373             cohortEntry.getReplySender().tell(new akka.actor.Status.Failure(e), cohortEntry.getShard().self());
 374
 375             currentTransactionComplete(cohortEntry.getTransactionID(), true);
 376         }
 377
 378         return success;
 379     }
 380
 381     /**
 382      * This method handles the preCommit and commit phases for a transaction.
 383      *
 384      * @param transactionID the ID of the transaction to commit
 385      * @param sender the actor to which to send the response
 386      * @param shard the transaction's shard actor
 387      * @return true if the transaction was successfully prepared, false otherwise.
 388      */
 389     boolean handleCommit(final String transactionID, final ActorRef sender, final Shard shard) {
 390         // Get the current in-progress cohort entry in the commitCoordinator if it corresponds to
 391         // this transaction.
 392         final CohortEntry cohortEntry = getCohortEntryIfCurrent(transactionID);
 393         if(cohortEntry == null) {
 394             // We're not the current Tx - the Tx was likely expired b/c it took too long in
 395             // between the canCommit and commit messages.
 396             IllegalStateException ex = new IllegalStateException(
 397                     String.format("%s: Cannot commit transaction %s - it is not the current transaction",
 398                             name, transactionID));
 399             log.error(ex.getMessage());
 400             sender.tell(new akka.actor.Status.Failure(ex), shard.self());
 401             return false;
 402         }
 403
 404         cohortEntry.setReplySender(sender);
 405         return doCommit(cohortEntry);
 406     }
 407
 408     /**
 409      * Returns the cohort entry for the Tx commit currently in progress if the given transaction ID
 410      * matches the current entry.
 411      *
 412      * @param transactionID the ID of the transaction
 413      * @return the current CohortEntry or null if the given transaction ID does not match the
 414      *         current entry.
 415      */
 416     public CohortEntry getCohortEntryIfCurrent(String transactionID) {
 417         if(isCurrentTransaction(transactionID)) {
 418             return currentCohortEntry;
 419         }
 420
 421         return null;
 422     }
 423
 424     public CohortEntry getCurrentCohortEntry() {
 425         return currentCohortEntry;
 426     }
 427
 428     public CohortEntry getAndRemoveCohortEntry(String transactionID) {
 429         return cohortCache.remove(transactionID);
 430     }
 431
 432     public boolean isCurrentTransaction(String transactionID) {
 433         return currentCohortEntry != null &&
 434                 currentCohortEntry.getTransactionID().equals(transactionID);
 435     }
 436
 437     /**
 438      * This method is called when a transaction is complete, successful or not. If the given
 439      * given transaction ID matches the current in-progress transaction, the next cohort entry,
 440      * if any, is dequeued and processed.
 441      *
 442      * @param transactionID the ID of the completed transaction
 443      * @param removeCohortEntry if true the CohortEntry for the transaction is also removed from
 444      *        the cache.
 445      */
 446     public void currentTransactionComplete(String transactionID, boolean removeCohortEntry) {
 447         if(removeCohortEntry) {
 448             cohortCache.remove(transactionID);
 449         }
 450
 451         if(isCurrentTransaction(transactionID)) {
 452             currentCohortEntry = null;
 453
 454             log.debug("{}: currentTransactionComplete: {}", name, transactionID);
 455
 456             maybeProcessNextCohortEntry();
 457         }
 458     }
 459
 460     private void maybeProcessNextCohortEntry() {
 461         // Check if there's a next cohort entry waiting in the queue and if it is ready to commit. Also
 462         // clean out expired entries.
 463         Iterator<CohortEntry> iter = queuedCohortEntries.iterator();
 464         while(iter.hasNext()) {
 465             CohortEntry next = iter.next();
 466             if(next.isReadyToCommit()) {
 467                 if(currentCohortEntry == null) {
 468                     if(log.isDebugEnabled()) {
 469                         log.debug("{}: Next entry to canCommit {}", name, next);
 470                     }
 471
 472                     iter.remove();
 473                     currentCohortEntry = next;
 474                     currentCohortEntry.updateLastAccessTime();
 475                     doCanCommit(currentCohortEntry);
 476                 }
 477
 478                 break;
 479             } else if(next.isExpired(cacheExpiryTimeoutInMillis)) {
 480                 log.warn("{}: canCommit for transaction {} was not received within {} ms - entry removed from cache",
 481                         name, next.getTransactionID(), cacheExpiryTimeoutInMillis);
 482
 483                 iter.remove();
 484                 cohortCache.remove(next.getTransactionID());
 485             } else {
 486                 break;
 487             }
 488         }
 489     }
 490
 491     void cleanupExpiredCohortEntries() {
 492         maybeProcessNextCohortEntry();
 493     }
 494
 495     @VisibleForTesting
 496     void setCohortDecorator(CohortDecorator cohortDecorator) {
 497         this.cohortDecorator = cohortDecorator;
 498     }
 499
 500     static class CohortEntry {
 501         private final String transactionID;
 502         private ShardDataTreeCohort cohort;
 503         private final ReadWriteShardDataTreeTransaction transaction;
 504         private RuntimeException lastBatchedModificationsException;
 505         private ActorRef replySender;
 506         private Shard shard;
 507         private boolean doImmediateCommit;
 508         private final Stopwatch lastAccessTimer = Stopwatch.createStarted();
 509         private int totalBatchedModificationsReceived;
 510
 511         CohortEntry(String transactionID, ReadWriteShardDataTreeTransaction transaction) {
 512             this.transaction = Preconditions.checkNotNull(transaction);
 513             this.transactionID = transactionID;
 514         }
 515
 516         CohortEntry(String transactionID, ShardDataTreeCohort cohort,
 517                 MutableCompositeModification compositeModification) {
 518             this.transactionID = transactionID;
 519             this.cohort = cohort;
 520             this.transaction = null;
 521         }
 522
 523         CohortEntry(String transactionID, ShardDataTreeCohort cohort) {
 524             this.transactionID = transactionID;
 525             this.cohort = cohort;
 526             this.transaction = null;
 527         }
 528
 529         void updateLastAccessTime() {
 530             lastAccessTimer.reset();
 531             lastAccessTimer.start();
 532         }
 533
 534         String getTransactionID() {
 535             return transactionID;
 536         }
 537
 538         ShardDataTreeCohort getCohort() {
 539             return cohort;
 540         }
 541
 542         int getTotalBatchedModificationsReceived() {
 543             return totalBatchedModificationsReceived;
 544         }
 545
 546         RuntimeException getLastBatchedModificationsException() {
 547             return lastBatchedModificationsException;
 548         }
 549
 550         void applyModifications(Iterable<Modification> modifications) {
 551             totalBatchedModificationsReceived++;
 552             if(lastBatchedModificationsException == null) {
 553                 for (Modification modification : modifications) {
 554                         try {
 555                             modification.apply(transaction.getSnapshot());
 556                         } catch (RuntimeException e) {
 557                             lastBatchedModificationsException = e;
 558                             throw e;
 559                         }
 560                 }
 561             }
 562         }
 563
 564         void ready(CohortDecorator cohortDecorator, boolean doImmediateCommit) {
 565             Preconditions.checkState(cohort == null, "cohort was already set");
 566
 567             setDoImmediateCommit(doImmediateCommit);
 568
 569             cohort = transaction.ready();
 570
 571             if(cohortDecorator != null) {
 572                 // Call the hook for unit tests.
 573                 cohort = cohortDecorator.decorate(transactionID, cohort);
 574             }
 575         }
 576
 577         boolean isReadyToCommit() {
 578             return replySender != null;
 579         }
 580
 581         boolean isExpired(long expireTimeInMillis) {
 582             return lastAccessTimer.elapsed(TimeUnit.MILLISECONDS) >= expireTimeInMillis;
 583         }
 584
 585         boolean isDoImmediateCommit() {
 586             return doImmediateCommit;
 587         }
 588
 589         void setDoImmediateCommit(boolean doImmediateCommit) {
 590             this.doImmediateCommit = doImmediateCommit;
 591         }
 592
 593         ActorRef getReplySender() {
 594             return replySender;
 595         }
 596
 597         void setReplySender(ActorRef replySender) {
 598             this.replySender = replySender;
 599         }
 600
 601         Shard getShard() {
 602             return shard;
 603         }
 604
 605         void setShard(Shard shard) {
 606             this.shard = shard;
 607         }
 608
 609         @Override
 610         public String toString() {
 611             StringBuilder builder = new StringBuilder();
 612             builder.append("CohortEntry [transactionID=").append(transactionID).append(", doImmediateCommit=")
 613                     .append(doImmediateCommit).append("]");
 614             return builder.toString();
 615         }
 616     }
 617 }