opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/RaftActorServerConfigurationSupport.java

   1 /*
   2  * Copyright (c) 2015 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.raft;
   9
  10 import akka.actor.ActorRef;
  11 import akka.actor.ActorSelection;
  12 import akka.actor.Cancellable;
  13 import com.google.common.base.Preconditions;
  14 import java.util.ArrayDeque;
  15 import java.util.Queue;
  16 import java.util.UUID;
  17 import javax.annotation.Nullable;
  18 import org.opendaylight.controller.cluster.raft.base.messages.ApplyState;
  19 import org.opendaylight.controller.cluster.raft.base.messages.SnapshotComplete;
  20 import org.opendaylight.controller.cluster.raft.behaviors.AbstractLeader;
  21 import org.opendaylight.controller.cluster.raft.messages.AddServer;
  22 import org.opendaylight.controller.cluster.raft.messages.AddServerReply;
  23 import org.opendaylight.controller.cluster.raft.messages.RemoveServer;
  24 import org.opendaylight.controller.cluster.raft.messages.RemoveServerReply;
  25 import org.opendaylight.controller.cluster.raft.messages.ServerChangeStatus;
  26 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
  27 import org.opendaylight.controller.cluster.raft.messages.UnInitializedFollowerSnapshotReply;
  28 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
  29 import org.slf4j.Logger;
  30 import org.slf4j.LoggerFactory;
  31
  32 /**
  33  * Handles server configuration related messages for a RaftActor.
  34  *
  35  * @author Thomas Pantelis
  36  */
  37 class RaftActorServerConfigurationSupport {
  38     private static final Logger LOG = LoggerFactory.getLogger(RaftActorServerConfigurationSupport.class);
  39
  40     private final OperationState IDLE = new Idle();
  41
  42     private final RaftActor raftActor;
  43
  44     private final RaftActorContext raftContext;
  45
  46     private final Queue<ServerOperationContext<?>> pendingOperationsQueue = new ArrayDeque<>();
  47
  48     private OperationState currentOperationState = IDLE;
  49
  50     RaftActorServerConfigurationSupport(RaftActor raftActor) {
  51         this.raftActor = raftActor;
  52         this.raftContext = raftActor.getRaftActorContext();
  53     }
  54
  55     boolean handleMessage(Object message, ActorRef sender) {
  56         if(message instanceof AddServer) {
  57             onAddServer((AddServer) message, sender);
  58             return true;
  59         } else if(message instanceof RemoveServer) {
  60             onRemoveServer((RemoveServer) message, sender);
  61             return true;
  62         } else if (message instanceof ServerOperationTimeout) {
  63             currentOperationState.onServerOperationTimeout((ServerOperationTimeout) message);
  64             return true;
  65         } else if (message instanceof UnInitializedFollowerSnapshotReply) {
  66             currentOperationState.onUnInitializedFollowerSnapshotReply((UnInitializedFollowerSnapshotReply) message);
  67             return true;
  68         } else if(message instanceof ApplyState) {
  69             return onApplyState((ApplyState) message);
  70         } else if(message instanceof SnapshotComplete) {
  71             currentOperationState.onSnapshotComplete();
  72             return false;
  73         } else {
  74             return false;
  75         }
  76     }
  77
  78     private void onRemoveServer(RemoveServer removeServer, ActorRef sender) {
  79         LOG.debug("{}: onRemoveServer: {}, state: {}", raftContext.getId(), removeServer, currentOperationState);
  80         boolean isSelf = removeServer.getServerId().equals(raftActor.getId());
  81         if(!isSelf && !raftContext.getPeerIds().contains(removeServer.getServerId())) {
  82             sender.tell(new RemoveServerReply(ServerChangeStatus.DOES_NOT_EXIST, raftActor.getLeaderId()),
  83                     raftActor.getSelf());
  84         } else {
  85             String serverAddress = isSelf ? raftActor.self().path().toString() :
  86                 raftContext.getPeerAddress(removeServer.getServerId());
  87             onNewOperation(new RemoveServerContext(removeServer, serverAddress, sender));
  88         }
  89     }
  90
  91     private boolean onApplyState(ApplyState applyState) {
  92         Payload data = applyState.getReplicatedLogEntry().getData();
  93         if(data instanceof ServerConfigurationPayload) {
  94             currentOperationState.onApplyState(applyState);
  95             return true;
  96         }
  97
  98         return false;
  99     }
 100
 101     /**
 102      * The algorithm for AddServer is as follows:
 103      * <ul>
 104      * <li>Add the new server as a peer.</li>
 105      * <li>Add the new follower to the leader.</li>
 106      * <li>If new server should be voting member</li>
 107      * <ul>
 108      *     <li>Initialize FollowerState to VOTING_NOT_INITIALIZED.</li>
 109      *     <li>Initiate install snapshot to the new follower.</li>
 110      *     <li>When install snapshot complete, mark the follower as VOTING and re-calculate majority vote count.</li>
 111      * </ul>
 112      * <li>Persist and replicate ServerConfigurationPayload with the new server list.</li>
 113      * <li>On replication consensus, respond to caller with OK.</li>
 114      * </ul>
 115      * If the install snapshot times out after a period of 2 * election time out
 116      * <ul>
 117      *     <li>Remove the new server as a peer.</li>
 118      *     <li>Remove the new follower from the leader.</li>
 119      *     <li>Respond to caller with TIMEOUT.</li>
 120      * </ul>
 121      */
 122     private void onAddServer(AddServer addServer, ActorRef sender) {
 123         LOG.debug("{}: onAddServer: {}, state: {}", raftContext.getId(), addServer, currentOperationState);
 124
 125         onNewOperation(new AddServerContext(addServer, sender));
 126     }
 127
 128     private void onNewOperation(ServerOperationContext<?> operationContext) {
 129         if (raftActor.isLeader()) {
 130             currentOperationState.onNewOperation(operationContext);
 131         } else {
 132             ActorSelection leader = raftActor.getLeader();
 133             if (leader != null) {
 134                 LOG.debug("{}: Not leader - forwarding to leader {}", raftContext.getId(), leader);
 135                 leader.forward(operationContext.getOperation(), raftActor.getContext());
 136             } else {
 137                 LOG.debug("{}: No leader - returning NO_LEADER reply", raftContext.getId());
 138                 operationContext.getClientRequestor().tell(operationContext.newReply(
 139                         ServerChangeStatus.NO_LEADER, null), raftActor.self());
 140             }
 141         }
 142     }
 143
 144     /**
 145      * Interface for a server operation FSM state.
 146      */
 147     private interface OperationState {
 148         void onNewOperation(ServerOperationContext<?> operationContext);
 149
 150         void onServerOperationTimeout(ServerOperationTimeout timeout);
 151
 152         void onUnInitializedFollowerSnapshotReply(UnInitializedFollowerSnapshotReply reply);
 153
 154         void onApplyState(ApplyState applyState);
 155
 156         void onSnapshotComplete();
 157     }
 158
 159     /**
 160      * Interface for the initial state for a server operation.
 161      */
 162     private interface InitialOperationState {
 163         void initiate();
 164     }
 165
 166     /**
 167      * Abstract base class for a server operation FSM state. Handles common behavior for all states.
 168      */
 169     private abstract class AbstractOperationState implements OperationState {
 170         @Override
 171         public void onNewOperation(ServerOperationContext<?> operationContext) {
 172             // We're currently processing another operation so queue it to be processed later.
 173
 174             LOG.debug("{}: Server operation already in progress - queueing {}", raftContext.getId(),
 175                     operationContext.getOperation());
 176
 177             pendingOperationsQueue.add(operationContext);
 178         }
 179
 180         @Override
 181         public void onServerOperationTimeout(ServerOperationTimeout timeout) {
 182             LOG.debug("onServerOperationTimeout should not be called in state {}", this);
 183         }
 184
 185         @Override
 186         public void onUnInitializedFollowerSnapshotReply(UnInitializedFollowerSnapshotReply reply) {
 187             LOG.debug("onUnInitializedFollowerSnapshotReply was called in state {}", this);
 188         }
 189
 190         @Override
 191         public void onApplyState(ApplyState applyState) {
 192             LOG.debug("onApplyState was called in state {}", this);
 193         }
 194
 195         @Override
 196         public void onSnapshotComplete() {
 197         }
 198
 199         protected void persistNewServerConfiguration(ServerOperationContext<?> operationContext){
 200             raftContext.setDynamicServerConfigurationInUse();
 201
 202             boolean includeSelf = !operationContext.getServerId().equals(raftActor.getId());
 203             ServerConfigurationPayload payload = raftContext.getPeerServerInfo(includeSelf);
 204             LOG.debug("{}: New server configuration : {}", raftContext.getId(), payload.getServerConfig());
 205
 206             raftActor.persistData(operationContext.getClientRequestor(), operationContext.getContextId(), payload);
 207
 208             currentOperationState = new Persisting(operationContext, newTimer(new ServerOperationTimeout(operationContext.getServerId())));
 209
 210             sendReply(operationContext, ServerChangeStatus.OK);
 211         }
 212
 213         protected void operationComplete(ServerOperationContext<?> operationContext, @Nullable ServerChangeStatus replyStatus) {
 214             if(replyStatus != null) {
 215                 sendReply(operationContext, replyStatus);
 216             }
 217
 218             operationContext.operationComplete(raftActor, replyStatus);
 219
 220             currentOperationState = IDLE;
 221
 222             ServerOperationContext<?> nextOperation = pendingOperationsQueue.poll();
 223             if(nextOperation != null) {
 224                 RaftActorServerConfigurationSupport.this.onNewOperation(nextOperation);
 225             }
 226         }
 227
 228         protected void sendReply(ServerOperationContext<?> operationContext, ServerChangeStatus status) {
 229             LOG.debug("{}: Returning {} for operation {}", raftContext.getId(), status, operationContext.getOperation());
 230
 231             operationContext.getClientRequestor().tell(operationContext.newReply(status, raftActor.getLeaderId()),
 232                     raftActor.self());
 233         }
 234
 235         Cancellable newTimer(Object message) {
 236             return raftContext.getActorSystem().scheduler().scheduleOnce(
 237                     raftContext.getConfigParams().getElectionTimeOutInterval().$times(2), raftContext.getActor(), message,
 238                             raftContext.getActorSystem().dispatcher(), raftContext.getActor());
 239         }
 240
 241         @Override
 242         public String toString() {
 243             return getClass().getSimpleName();
 244         }
 245     }
 246
 247     /**
 248      * The state when no server operation is in progress. It immediately initiates new server operations.
 249      */
 250     private class Idle extends AbstractOperationState {
 251         @Override
 252         public void onNewOperation(ServerOperationContext<?> operationContext) {
 253             operationContext.newInitialOperationState(RaftActorServerConfigurationSupport.this).initiate();
 254         }
 255
 256         @Override
 257         public void onApplyState(ApplyState applyState) {
 258             // Noop - we override b/c ApplyState is called normally for followers in the idle state.
 259         }
 260     }
 261
 262     /**
 263      * The state when a new server configuration is being persisted and replicated.
 264      */
 265     private class Persisting extends AbstractOperationState {
 266         private final ServerOperationContext<?> operationContext;
 267         private final Cancellable timer;
 268         private boolean timedOut = false;
 269
 270         Persisting(ServerOperationContext<?> operationContext, Cancellable timer) {
 271             this.operationContext = operationContext;
 272             this.timer = timer;
 273         }
 274
 275         @Override
 276         public void onApplyState(ApplyState applyState) {
 277             // Sanity check - we could get an ApplyState from a previous operation that timed out so make
 278             // sure it's meant for us.
 279             if(operationContext.getContextId().equals(applyState.getIdentifier())) {
 280                 LOG.info("{}: {} has been successfully replicated to a majority of followers", raftActor.getId(),
 281                         applyState.getReplicatedLogEntry().getData());
 282
 283                 timer.cancel();
 284                 operationComplete(operationContext, null);
 285             }
 286         }
 287
 288         @Override
 289         public void onServerOperationTimeout(ServerOperationTimeout timeout) {
 290             LOG.warn("{}: Timeout occured while replicating the new server configuration for {}", raftContext.getId(),
 291                     timeout.getServerId());
 292
 293             timedOut = true;
 294
 295             // Fail any pending operations
 296             ServerOperationContext<?> nextOperation = pendingOperationsQueue.poll();
 297             while(nextOperation != null) {
 298                 sendReply(nextOperation, ServerChangeStatus.PRIOR_REQUEST_CONSENSUS_TIMEOUT);
 299                 nextOperation = pendingOperationsQueue.poll();
 300             }
 301         }
 302
 303         @Override
 304         public void onNewOperation(ServerOperationContext<?> operationContext) {
 305             if(timedOut) {
 306                 sendReply(operationContext, ServerChangeStatus.PRIOR_REQUEST_CONSENSUS_TIMEOUT);
 307             } else {
 308                 super.onNewOperation(operationContext);
 309             }
 310         }
 311     }
 312
 313     /**
 314      * Abstract base class for an AddServer operation state.
 315      */
 316     private abstract class AddServerState extends AbstractOperationState {
 317         private final AddServerContext addServerContext;
 318
 319         AddServerState(AddServerContext addServerContext) {
 320             this.addServerContext = addServerContext;
 321         }
 322
 323         AddServerContext getAddServerContext() {
 324             return addServerContext;
 325         }
 326
 327         Cancellable newInstallSnapshotTimer() {
 328             return newTimer(new ServerOperationTimeout(addServerContext.getOperation().getNewServerId()));
 329         }
 330
 331         void handleInstallSnapshotTimeout(ServerOperationTimeout timeout) {
 332             String serverId = timeout.getServerId();
 333
 334             LOG.debug("{}: handleInstallSnapshotTimeout for new server {}", raftContext.getId(), serverId);
 335
 336             // cleanup
 337             raftContext.removePeer(serverId);
 338
 339             boolean isLeader = raftActor.isLeader();
 340             if(isLeader) {
 341                 AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior();
 342                 leader.removeFollower(serverId);
 343             }
 344
 345             operationComplete(getAddServerContext(), isLeader ? ServerChangeStatus.TIMEOUT : ServerChangeStatus.NO_LEADER);
 346         }
 347
 348     }
 349
 350     /**
 351      * The initial state for the AddServer operation. It adds the new follower as a peer and initiates
 352      * snapshot capture, if necessary.
 353      */
 354     private class InitialAddServerState extends AddServerState implements InitialOperationState {
 355         InitialAddServerState(AddServerContext addServerContext) {
 356             super(addServerContext);
 357         }
 358
 359         @Override
 360         public void initiate() {
 361             AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior();
 362             AddServer addServer = getAddServerContext().getOperation();
 363
 364             LOG.debug("{}: Initiating {}", raftContext.getId(), addServer);
 365
 366             if(raftContext.getPeerInfo(addServer.getNewServerId()) != null) {
 367                 operationComplete(getAddServerContext(), ServerChangeStatus.ALREADY_EXISTS);
 368                 return;
 369             }
 370
 371             VotingState votingState = addServer.isVotingMember() ? VotingState.VOTING_NOT_INITIALIZED :
 372                     VotingState.NON_VOTING;
 373             raftContext.addToPeers(addServer.getNewServerId(), addServer.getNewServerAddress(), votingState);
 374
 375             leader.addFollower(addServer.getNewServerId());
 376
 377             if(votingState == VotingState.VOTING_NOT_INITIALIZED){
 378                 // schedule the install snapshot timeout timer
 379                 Cancellable installSnapshotTimer = newInstallSnapshotTimer();
 380                 if(leader.initiateCaptureSnapshot(addServer.getNewServerId())) {
 381                     LOG.debug("{}: Initiating capture snapshot for new server {}", raftContext.getId(),
 382                             addServer.getNewServerId());
 383
 384                     currentOperationState = new InstallingSnapshot(getAddServerContext(), installSnapshotTimer);
 385                 } else {
 386                     LOG.debug("{}: Snapshot already in progress - waiting for completion", raftContext.getId());
 387
 388                     currentOperationState = new WaitingForPriorSnapshotComplete(getAddServerContext(),
 389                             installSnapshotTimer);
 390                 }
 391             } else {
 392                 LOG.debug("{}: New follower is non-voting - directly persisting new server configuration",
 393                         raftContext.getId());
 394
 395                 persistNewServerConfiguration(getAddServerContext());
 396             }
 397         }
 398     }
 399
 400     /**
 401      * The AddServer operation state for when the catch-up snapshot is being installed. It handles successful
 402      * reply or timeout.
 403      */
 404     private class InstallingSnapshot extends AddServerState {
 405         private final Cancellable installSnapshotTimer;
 406
 407         InstallingSnapshot(AddServerContext addServerContext, Cancellable installSnapshotTimer) {
 408             super(addServerContext);
 409             this.installSnapshotTimer = Preconditions.checkNotNull(installSnapshotTimer);
 410         }
 411
 412         @Override
 413         public void onServerOperationTimeout(ServerOperationTimeout timeout) {
 414             handleInstallSnapshotTimeout(timeout);
 415
 416             LOG.warn("{}: Timeout occured for new server {} while installing snapshot", raftContext.getId(),
 417                     timeout.getServerId());
 418         }
 419
 420         @Override
 421         public void onUnInitializedFollowerSnapshotReply(UnInitializedFollowerSnapshotReply reply) {
 422             LOG.debug("{}: onUnInitializedFollowerSnapshotReply: {}", raftContext.getId(), reply);
 423
 424             String followerId = reply.getFollowerId();
 425
 426             // Sanity check to guard against receiving an UnInitializedFollowerSnapshotReply from a prior
 427             // add server operation that timed out.
 428             if(getAddServerContext().getOperation().getNewServerId().equals(followerId) && raftActor.isLeader()) {
 429                 AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior();
 430                 raftContext.getPeerInfo(followerId).setVotingState(VotingState.VOTING);
 431                 leader.updateMinReplicaCount();
 432
 433                 persistNewServerConfiguration(getAddServerContext());
 434
 435                 installSnapshotTimer.cancel();
 436             } else {
 437                 LOG.debug("{}: Dropping UnInitializedFollowerSnapshotReply for server {}: {}",
 438                         raftContext.getId(), followerId,
 439                         !raftActor.isLeader() ? "not leader" : "server Id doesn't match");
 440             }
 441         }
 442     }
 443
 444     /**
 445      * The AddServer operation state for when there is a snapshot already in progress. When the current
 446      * snapshot completes, it initiates an install snapshot.
 447      */
 448     private class WaitingForPriorSnapshotComplete extends AddServerState {
 449         private final Cancellable snapshotTimer;
 450
 451         WaitingForPriorSnapshotComplete(AddServerContext addServerContext, Cancellable snapshotTimer) {
 452             super(addServerContext);
 453             this.snapshotTimer = Preconditions.checkNotNull(snapshotTimer);
 454         }
 455
 456         @Override
 457         public void onSnapshotComplete() {
 458             LOG.debug("{}: onSnapshotComplete", raftContext.getId());
 459
 460             if(!raftActor.isLeader()) {
 461                 LOG.debug("{}: No longer the leader", raftContext.getId());
 462                 return;
 463             }
 464
 465             AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior();
 466             if(leader.initiateCaptureSnapshot(getAddServerContext().getOperation().getNewServerId())) {
 467                 LOG.debug("{}: Initiating capture snapshot for new server {}", raftContext.getId(),
 468                         getAddServerContext().getOperation().getNewServerId());
 469
 470                 currentOperationState = new InstallingSnapshot(getAddServerContext(),
 471                         newInstallSnapshotTimer());
 472
 473                 snapshotTimer.cancel();
 474             }
 475         }
 476
 477         @Override
 478         public void onServerOperationTimeout(ServerOperationTimeout timeout) {
 479             handleInstallSnapshotTimeout(timeout);
 480
 481             LOG.warn("{}: Timeout occured for new server {} while waiting for prior snapshot to complete",
 482                     raftContext.getId(), timeout.getServerId());
 483         }
 484     }
 485
 486     /**
 487      * Stores context information for a server operation.
 488      *
 489      * @param <T> the operation type
 490      */
 491     private static abstract class ServerOperationContext<T> {
 492         private final T operation;
 493         private final ActorRef clientRequestor;
 494         private final String contextId;
 495
 496         ServerOperationContext(T operation, ActorRef clientRequestor){
 497             this.operation = operation;
 498             this.clientRequestor = clientRequestor;
 499             contextId = UUID.randomUUID().toString();
 500         }
 501
 502         String getContextId() {
 503             return contextId;
 504         }
 505
 506         T getOperation() {
 507             return operation;
 508         }
 509
 510         ActorRef getClientRequestor() {
 511             return clientRequestor;
 512         }
 513
 514         abstract Object newReply(ServerChangeStatus status, String leaderId);
 515
 516         abstract InitialOperationState newInitialOperationState(RaftActorServerConfigurationSupport support);
 517
 518         abstract void operationComplete(RaftActor raftActor, ServerChangeStatus serverChangeStatus);
 519
 520         abstract String getServerId();
 521     }
 522
 523     /**
 524      * Stores context information for an AddServer operation.
 525      */
 526     private static class AddServerContext extends ServerOperationContext<AddServer> {
 527         AddServerContext(AddServer addServer, ActorRef clientRequestor) {
 528             super(addServer, clientRequestor);
 529         }
 530
 531         @Override
 532         Object newReply(ServerChangeStatus status, String leaderId) {
 533             return new AddServerReply(status, leaderId);
 534         }
 535
 536         @Override
 537         InitialOperationState newInitialOperationState(RaftActorServerConfigurationSupport support) {
 538             return support.new InitialAddServerState(this);
 539         }
 540
 541         @Override
 542         void operationComplete(RaftActor raftActor, ServerChangeStatus serverChangeStatus) {
 543
 544         }
 545
 546         @Override
 547         String getServerId() {
 548             return getOperation().getNewServerId();
 549         }
 550     }
 551
 552     private abstract class RemoveServerState extends AbstractOperationState {
 553         private final RemoveServerContext removeServerContext;
 554
 555
 556         protected RemoveServerState(RemoveServerContext removeServerContext) {
 557             this.removeServerContext = Preconditions.checkNotNull(removeServerContext);
 558
 559         }
 560
 561         public RemoveServerContext getRemoveServerContext() {
 562             return removeServerContext;
 563         }
 564     }
 565
 566     private class InitialRemoveServerState extends RemoveServerState implements InitialOperationState{
 567
 568         protected InitialRemoveServerState(RemoveServerContext removeServerContext) {
 569             super(removeServerContext);
 570         }
 571
 572         @Override
 573         public void initiate() {
 574             raftContext.removePeer(getRemoveServerContext().getOperation().getServerId());
 575             persistNewServerConfiguration(getRemoveServerContext());
 576         }
 577     }
 578
 579     private static class RemoveServerContext extends ServerOperationContext<RemoveServer> {
 580         private final String peerAddress;
 581
 582         RemoveServerContext(RemoveServer operation, String peerAddress, ActorRef clientRequestor) {
 583             super(operation, clientRequestor);
 584             this.peerAddress = peerAddress;
 585         }
 586
 587         @Override
 588         Object newReply(ServerChangeStatus status, String leaderId) {
 589             return new RemoveServerReply(status, leaderId);
 590         }
 591
 592         @Override
 593         InitialOperationState newInitialOperationState(RaftActorServerConfigurationSupport support) {
 594             return support.new InitialRemoveServerState(this);
 595         }
 596
 597         @Override
 598         void operationComplete(RaftActor raftActor, ServerChangeStatus serverChangeStatus) {
 599             if(peerAddress != null) {
 600                 raftActor.context().actorSelection(peerAddress).tell(new ServerRemoved(getOperation().getServerId()), raftActor.getSelf());
 601             }
 602         }
 603
 604         @Override
 605         String getServerId() {
 606             return getOperation().getServerId();
 607         }
 608     }
 609
 610     static class ServerOperationTimeout {
 611         private final String serverId;
 612
 613         ServerOperationTimeout(String serverId){
 614            this.serverId = Preconditions.checkNotNull(serverId, "serverId should not be null");
 615         }
 616
 617         String getServerId() {
 618             return serverId;
 619         }
 620     }
 621 }