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.getTotalBatchedModificationsReceived() != batched.getTotalMessagesSent()) {
 188                 throw new IllegalStateException(String.format(
 189                         "The total number of batched messages received %d does not match the number sent %d",
 190                         cohortEntry.getTotalBatchedModificationsReceived(), batched.getTotalMessagesSent()));
 191             }
 192
 193             if(!queueCohortEntry(cohortEntry, sender, shard)) {
 194                 return;
 195             }
 196
 197             if(log.isDebugEnabled()) {
 198                 log.debug("{}: Readying Tx {}, client version {}", name,
 199                         batched.getTransactionID(), batched.getVersion());
 200             }
 201
 202             cohortEntry.ready(cohortDecorator, batched.isDoCommitOnReady());
 203
 204             if(batched.isDoCommitOnReady()) {
 205                 cohortEntry.setReplySender(sender);
 206                 cohortEntry.setShard(shard);
 207                 handleCanCommit(cohortEntry);
 208             } else {
 209                 sender.tell(readyTransactionReply(shard), shard.self());
 210             }
 211         } else {
 212             sender.tell(new BatchedModificationsReply(batched.getModifications().size()), shard.self());
 213         }
 214     }
 215
 216     /**
 217      * This method handles {@link ReadyLocalTransaction} message. All transaction modifications have
 218      * been prepared beforehand by the sender and we just need to drive them through into the dataTree.
 219      *
 220      * @param message the ReadyLocalTransaction message to process
 221      * @param sender the sender of the message
 222      * @param shard the transaction's shard actor
 223      */
 224     void handleReadyLocalTransaction(ReadyLocalTransaction message, ActorRef sender, Shard shard) {
 225         final ShardDataTreeCohort cohort = new SimpleShardDataTreeCohort(dataTree, message.getModification(),
 226                 message.getTransactionID());
 227         final CohortEntry cohortEntry = new CohortEntry(message.getTransactionID(), cohort);
 228         cohortCache.put(message.getTransactionID(), cohortEntry);
 229         cohortEntry.setDoImmediateCommit(message.isDoCommitOnReady());
 230
 231         if(!queueCohortEntry(cohortEntry, sender, shard)) {
 232             return;
 233         }
 234
 235         log.debug("{}: Applying local modifications for Tx {}", name, message.getTransactionID());
 236
 237         if (message.isDoCommitOnReady()) {
 238             cohortEntry.setReplySender(sender);
 239             cohortEntry.setShard(shard);
 240             handleCanCommit(cohortEntry);
 241         } else {
 242             sender.tell(readyTransactionReply(shard), shard.self());
 243         }
 244     }
 245
 246     private void handleCanCommit(CohortEntry cohortEntry) {
 247         String transactionID = cohortEntry.getTransactionID();
 248
 249         cohortEntry.updateLastAccessTime();
 250
 251         if(currentCohortEntry != null) {
 252             // There's already a Tx commit in progress so we can't process this entry yet - but it's in the
 253             // queue and will get processed after all prior entries complete.
 254
 255             if(log.isDebugEnabled()) {
 256                 log.debug("{}: Commit for Tx {} already in progress - skipping canCommit for {} for now",
 257                         name, currentCohortEntry.getTransactionID(), transactionID);
 258             }
 259
 260             return;
 261         }
 262
 263         // No Tx commit currently in progress - check if this entry is the next one in the queue, If so make
 264         // it the current entry and proceed with canCommit.
 265         // Purposely checking reference equality here.
 266         if(queuedCohortEntries.peek() == cohortEntry) {
 267             currentCohortEntry = queuedCohortEntries.poll();
 268             doCanCommit(currentCohortEntry);
 269         } else {
 270             if(log.isDebugEnabled()) {
 271                 log.debug("{}: Tx {} is the next pending canCommit - skipping {} for now",
 272                         name, queuedCohortEntries.peek().getTransactionID(), transactionID);
 273             }
 274         }
 275     }
 276
 277     /**
 278      * This method handles the canCommit phase for a transaction.
 279      *
 280      * @param transactionID the ID of the transaction to canCommit
 281      * @param sender the actor to which to send the response
 282      * @param shard the transaction's shard actor
 283      */
 284     void handleCanCommit(String transactionID, final ActorRef sender, final Shard shard) {
 285         // Lookup the cohort entry that was cached previously (or should have been) by
 286         // transactionReady (via the ForwardedReadyTransaction message).
 287         final CohortEntry cohortEntry = cohortCache.get(transactionID);
 288         if(cohortEntry == null) {
 289             // Either canCommit was invoked before ready(shouldn't happen)  or a long time passed
 290             // between canCommit and ready and the entry was expired from the cache.
 291             IllegalStateException ex = new IllegalStateException(
 292                     String.format("%s: No cohort entry found for transaction %s", name, transactionID));
 293             log.error(ex.getMessage());
 294             sender.tell(new Status.Failure(ex), shard.self());
 295             return;
 296         }
 297
 298         cohortEntry.setReplySender(sender);
 299         cohortEntry.setShard(shard);
 300
 301         handleCanCommit(cohortEntry);
 302     }
 303
 304     private void doCanCommit(final CohortEntry cohortEntry) {
 305         boolean canCommit = false;
 306         try {
 307             // We block on the future here so we don't have to worry about possibly accessing our
 308             // state on a different thread outside of our dispatcher. Also, the data store
 309             // currently uses a same thread executor anyway.
 310             canCommit = cohortEntry.getCohort().canCommit().get();
 311
 312             log.debug("{}: canCommit for {}: {}", name, cohortEntry.getTransactionID(), canCommit);
 313
 314             if(cohortEntry.isDoImmediateCommit()) {
 315                 if(canCommit) {
 316                     doCommit(cohortEntry);
 317                 } else {
 318                     cohortEntry.getReplySender().tell(new Status.Failure(new TransactionCommitFailedException(
 319                                 "Can Commit failed, no detailed cause available.")), cohortEntry.getShard().self());
 320                 }
 321             } else {
 322                 cohortEntry.getReplySender().tell(
 323                         canCommit ? CanCommitTransactionReply.YES.toSerializable() :
 324                             CanCommitTransactionReply.NO.toSerializable(), cohortEntry.getShard().self());
 325             }
 326         } catch (Exception e) {
 327             log.debug("{}: An exception occurred during canCommit", name, e);
 328
 329             Throwable failure = e;
 330             if(e instanceof ExecutionException) {
 331                 failure = e.getCause();
 332             }
 333
 334             cohortEntry.getReplySender().tell(new Status.Failure(failure), cohortEntry.getShard().self());
 335         } finally {
 336             if(!canCommit) {
 337                 // Remove the entry from the cache now.
 338                 currentTransactionComplete(cohortEntry.getTransactionID(), true);
 339             }
 340         }
 341     }
 342
 343     private boolean doCommit(CohortEntry cohortEntry) {
 344         log.debug("{}: Committing transaction {}", name, cohortEntry.getTransactionID());
 345
 346         boolean success = false;
 347
 348         // We perform the preCommit phase here atomically with the commit phase. This is an
 349         // optimization to eliminate the overhead of an extra preCommit message. We lose front-end
 350         // coordination of preCommit across shards in case of failure but preCommit should not
 351         // normally fail since we ensure only one concurrent 3-phase commit.
 352
 353         try {
 354             // We block on the future here so we don't have to worry about possibly accessing our
 355             // state on a different thread outside of our dispatcher. Also, the data store
 356             // currently uses a same thread executor anyway.
 357             cohortEntry.getCohort().preCommit().get();
 358
 359             cohortEntry.getShard().continueCommit(cohortEntry);
 360
 361             cohortEntry.updateLastAccessTime();
 362
 363             success = true;
 364         } catch (Exception e) {
 365             log.error("{} An exception occurred while preCommitting transaction {}",
 366                     name, cohortEntry.getTransactionID(), e);
 367             cohortEntry.getReplySender().tell(new akka.actor.Status.Failure(e), cohortEntry.getShard().self());
 368
 369             currentTransactionComplete(cohortEntry.getTransactionID(), true);
 370         }
 371
 372         return success;
 373     }
 374
 375     /**
 376      * This method handles the preCommit and commit phases for a transaction.
 377      *
 378      * @param transactionID the ID of the transaction to commit
 379      * @param sender the actor to which to send the response
 380      * @param shard the transaction's shard actor
 381      * @return true if the transaction was successfully prepared, false otherwise.
 382      */
 383     boolean handleCommit(final String transactionID, final ActorRef sender, final Shard shard) {
 384         // Get the current in-progress cohort entry in the commitCoordinator if it corresponds to
 385         // this transaction.
 386         final CohortEntry cohortEntry = getCohortEntryIfCurrent(transactionID);
 387         if(cohortEntry == null) {
 388             // We're not the current Tx - the Tx was likely expired b/c it took too long in
 389             // between the canCommit and commit messages.
 390             IllegalStateException ex = new IllegalStateException(
 391                     String.format("%s: Cannot commit transaction %s - it is not the current transaction",
 392                             name, transactionID));
 393             log.error(ex.getMessage());
 394             sender.tell(new akka.actor.Status.Failure(ex), shard.self());
 395             return false;
 396         }
 397
 398         cohortEntry.setReplySender(sender);
 399         return doCommit(cohortEntry);
 400     }
 401
 402     /**
 403      * Returns the cohort entry for the Tx commit currently in progress if the given transaction ID
 404      * matches the current entry.
 405      *
 406      * @param transactionID the ID of the transaction
 407      * @return the current CohortEntry or null if the given transaction ID does not match the
 408      *         current entry.
 409      */
 410     public CohortEntry getCohortEntryIfCurrent(String transactionID) {
 411         if(isCurrentTransaction(transactionID)) {
 412             return currentCohortEntry;
 413         }
 414
 415         return null;
 416     }
 417
 418     public CohortEntry getCurrentCohortEntry() {
 419         return currentCohortEntry;
 420     }
 421
 422     public CohortEntry getAndRemoveCohortEntry(String transactionID) {
 423         return cohortCache.remove(transactionID);
 424     }
 425
 426     public boolean isCurrentTransaction(String transactionID) {
 427         return currentCohortEntry != null &&
 428                 currentCohortEntry.getTransactionID().equals(transactionID);
 429     }
 430
 431     /**
 432      * This method is called when a transaction is complete, successful or not. If the given
 433      * given transaction ID matches the current in-progress transaction, the next cohort entry,
 434      * if any, is dequeued and processed.
 435      *
 436      * @param transactionID the ID of the completed transaction
 437      * @param removeCohortEntry if true the CohortEntry for the transaction is also removed from
 438      *        the cache.
 439      */
 440     public void currentTransactionComplete(String transactionID, boolean removeCohortEntry) {
 441         if(removeCohortEntry) {
 442             cohortCache.remove(transactionID);
 443         }
 444
 445         if(isCurrentTransaction(transactionID)) {
 446             currentCohortEntry = null;
 447
 448             log.debug("{}: currentTransactionComplete: {}", name, transactionID);
 449
 450             maybeProcessNextCohortEntry();
 451         }
 452     }
 453
 454     private void maybeProcessNextCohortEntry() {
 455         // Check if there's a next cohort entry waiting in the queue and if it is ready to commit. Also
 456         // clean out expired entries.
 457         Iterator<CohortEntry> iter = queuedCohortEntries.iterator();
 458         while(iter.hasNext()) {
 459             CohortEntry next = iter.next();
 460             if(next.isReadyToCommit()) {
 461                 if(currentCohortEntry == null) {
 462                     if(log.isDebugEnabled()) {
 463                         log.debug("{}: Next entry to canCommit {}", name, next);
 464                     }
 465
 466                     iter.remove();
 467                     currentCohortEntry = next;
 468                     currentCohortEntry.updateLastAccessTime();
 469                     doCanCommit(currentCohortEntry);
 470                 }
 471
 472                 break;
 473             } else if(next.isExpired(cacheExpiryTimeoutInMillis)) {
 474                 log.warn("{}: canCommit for transaction {} was not received within {} ms - entry removed from cache",
 475                         name, next.getTransactionID(), cacheExpiryTimeoutInMillis);
 476
 477                 iter.remove();
 478                 cohortCache.remove(next.getTransactionID());
 479             } else {
 480                 break;
 481             }
 482         }
 483     }
 484
 485     void cleanupExpiredCohortEntries() {
 486         maybeProcessNextCohortEntry();
 487     }
 488
 489     @VisibleForTesting
 490     void setCohortDecorator(CohortDecorator cohortDecorator) {
 491         this.cohortDecorator = cohortDecorator;
 492     }
 493
 494     static class CohortEntry {
 495         private final String transactionID;
 496         private ShardDataTreeCohort cohort;
 497         private final ReadWriteShardDataTreeTransaction transaction;
 498         private ActorRef replySender;
 499         private Shard shard;
 500         private boolean doImmediateCommit;
 501         private final Stopwatch lastAccessTimer = Stopwatch.createStarted();
 502         private int totalBatchedModificationsReceived;
 503
 504         CohortEntry(String transactionID, ReadWriteShardDataTreeTransaction transaction) {
 505             this.transaction = Preconditions.checkNotNull(transaction);
 506             this.transactionID = transactionID;
 507         }
 508
 509         CohortEntry(String transactionID, ShardDataTreeCohort cohort,
 510                 MutableCompositeModification compositeModification) {
 511             this.transactionID = transactionID;
 512             this.cohort = cohort;
 513             this.transaction = null;
 514         }
 515
 516         CohortEntry(String transactionID, ShardDataTreeCohort cohort) {
 517             this.transactionID = transactionID;
 518             this.cohort = cohort;
 519             this.transaction = null;
 520         }
 521
 522         void updateLastAccessTime() {
 523             lastAccessTimer.reset();
 524             lastAccessTimer.start();
 525         }
 526
 527         String getTransactionID() {
 528             return transactionID;
 529         }
 530
 531         ShardDataTreeCohort getCohort() {
 532             return cohort;
 533         }
 534
 535         int getTotalBatchedModificationsReceived() {
 536             return totalBatchedModificationsReceived;
 537         }
 538
 539         void applyModifications(Iterable<Modification> modifications) {
 540             for (Modification modification : modifications) {
 541                 modification.apply(transaction.getSnapshot());
 542             }
 543
 544             totalBatchedModificationsReceived++;
 545         }
 546
 547         void ready(CohortDecorator cohortDecorator, boolean doImmediateCommit) {
 548             Preconditions.checkState(cohort == null, "cohort was already set");
 549
 550             setDoImmediateCommit(doImmediateCommit);
 551
 552             cohort = transaction.ready();
 553
 554             if(cohortDecorator != null) {
 555                 // Call the hook for unit tests.
 556                 cohort = cohortDecorator.decorate(transactionID, cohort);
 557             }
 558         }
 559
 560         boolean isReadyToCommit() {
 561             return replySender != null;
 562         }
 563
 564         boolean isExpired(long expireTimeInMillis) {
 565             return lastAccessTimer.elapsed(TimeUnit.MILLISECONDS) >= expireTimeInMillis;
 566         }
 567
 568         boolean isDoImmediateCommit() {
 569             return doImmediateCommit;
 570         }
 571
 572         void setDoImmediateCommit(boolean doImmediateCommit) {
 573             this.doImmediateCommit = doImmediateCommit;
 574         }
 575
 576         ActorRef getReplySender() {
 577             return replySender;
 578         }
 579
 580         void setReplySender(ActorRef replySender) {
 581             this.replySender = replySender;
 582         }
 583
 584         Shard getShard() {
 585             return shard;
 586         }
 587
 588         void setShard(Shard shard) {
 589             this.shard = shard;
 590         }
 591
 592         @Override
 593         public String toString() {
 594             StringBuilder builder = new StringBuilder();
 595             builder.append("CohortEntry [transactionID=").append(transactionID).append(", doImmediateCommit=")
 596                     .append(doImmediateCommit).append("]");
 597             return builder.toString();
 598         }
 599     }
 600 }