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

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  * Copyright (c) 2015 Brocade Communications Systems, Inc. and others.  All rights reserved.
   4  *
   5  * This program and the accompanying materials are made available under the
   6  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   7  * and is available at http://www.eclipse.org/legal/epl-v10.html
   8  */
   9
  10 package org.opendaylight.controller.cluster.raft;
  11
  12 import akka.actor.ActorRef;
  13 import akka.actor.ActorSelection;
  14 import akka.japi.Procedure;
  15 import com.google.common.annotations.VisibleForTesting;
  16 import com.google.common.base.Objects;
  17 import com.google.common.base.Optional;
  18 import com.google.common.base.Supplier;
  19 import com.google.common.collect.Lists;
  20 import java.io.Serializable;
  21 import java.util.Collection;
  22 import java.util.List;
  23 import java.util.Map;
  24 import java.util.concurrent.TimeUnit;
  25 import javax.annotation.Nonnull;
  26 import org.apache.commons.lang3.time.DurationFormatUtils;
  27 import org.opendaylight.controller.cluster.DataPersistenceProvider;
  28 import org.opendaylight.controller.cluster.DelegatingPersistentDataProvider;
  29 import org.opendaylight.controller.cluster.NonPersistentDataProvider;
  30 import org.opendaylight.controller.cluster.PersistentDataProvider;
  31 import org.opendaylight.controller.cluster.common.actor.AbstractUntypedPersistentActor;
  32 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
  33 import org.opendaylight.controller.cluster.notifications.RoleChanged;
  34 import org.opendaylight.controller.cluster.raft.base.messages.ApplyJournalEntries;
  35 import org.opendaylight.controller.cluster.raft.base.messages.ApplyState;
  36 import org.opendaylight.controller.cluster.raft.base.messages.InitiateCaptureSnapshot;
  37 import org.opendaylight.controller.cluster.raft.base.messages.Replicate;
  38 import org.opendaylight.controller.cluster.raft.base.messages.SwitchBehavior;
  39 import org.opendaylight.controller.cluster.raft.behaviors.AbstractLeader;
  40 import org.opendaylight.controller.cluster.raft.behaviors.DelegatingRaftActorBehavior;
  41 import org.opendaylight.controller.cluster.raft.behaviors.Follower;
  42 import org.opendaylight.controller.cluster.raft.behaviors.RaftActorBehavior;
  43 import org.opendaylight.controller.cluster.raft.client.messages.FindLeader;
  44 import org.opendaylight.controller.cluster.raft.client.messages.FindLeaderReply;
  45 import org.opendaylight.controller.cluster.raft.client.messages.FollowerInfo;
  46 import org.opendaylight.controller.cluster.raft.client.messages.GetOnDemandRaftState;
  47 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
  48 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
  49 import org.slf4j.Logger;
  50 import org.slf4j.LoggerFactory;
  51
  52 /**
  53  * RaftActor encapsulates a state machine that needs to be kept synchronized
  54  * in a cluster. It implements the RAFT algorithm as described in the paper
  55  * <a href='https://ramcloud.stanford.edu/wiki/download/attachments/11370504/raft.pdf'>
  56  * In Search of an Understandable Consensus Algorithm</a>
  57  * <p/>
  58  * RaftActor has 3 states and each state has a certain behavior associated
  59  * with it. A Raft actor can behave as,
  60  * <ul>
  61  * <li> A Leader </li>
  62  * <li> A Follower (or) </li>
  63  * <li> A Candidate </li>
  64  * </ul>
  65  * <p/>
  66  * <p/>
  67  * A RaftActor MUST be a Leader in order to accept requests from clients to
  68  * change the state of it's encapsulated state machine. Once a RaftActor becomes
  69  * a Leader it is also responsible for ensuring that all followers ultimately
  70  * have the same log and therefore the same state machine as itself.
  71  * <p/>
  72  * <p/>
  73  * The current behavior of a RaftActor determines how election for leadership
  74  * is initiated and how peer RaftActors react to request for votes.
  75  * <p/>
  76  * <p/>
  77  * Each RaftActor also needs to know the current election term. It uses this
  78  * information for a couple of things. One is to simply figure out who it
  79  * voted for in the last election. Another is to figure out if the message
  80  * it received to update it's state is stale.
  81  * <p/>
  82  * <p/>
  83  * The RaftActor uses akka-persistence to store it's replicated log.
  84  * Furthermore through it's behaviors a Raft Actor determines
  85  * <p/>
  86  * <ul>
  87  * <li> when a log entry should be persisted </li>
  88  * <li> when a log entry should be applied to the state machine (and) </li>
  89  * <li> when a snapshot should be saved </li>
  90  * </ul>
  91  */
  92 public abstract class RaftActor extends AbstractUntypedPersistentActor {
  93
  94     private static final long APPLY_STATE_DELAY_THRESHOLD_IN_NANOS = TimeUnit.MILLISECONDS.toNanos(50L); // 50 millis
  95
  96     protected final Logger LOG = LoggerFactory.getLogger(getClass());
  97
  98     /**
  99      * The current state determines the current behavior of a RaftActor
 100      * A Raft Actor always starts off in the Follower State
 101      */
 102     private final DelegatingRaftActorBehavior currentBehavior = new DelegatingRaftActorBehavior();
 103
 104     /**
 105      * This context should NOT be passed directly to any other actor it is
 106      * only to be consumed by the RaftActorBehaviors
 107      */
 108     private final RaftActorContextImpl context;
 109
 110     private final DelegatingPersistentDataProvider delegatingPersistenceProvider = new DelegatingPersistentDataProvider(null);
 111
 112     private final PersistentDataProvider persistentProvider;
 113
 114     private RaftActorRecoverySupport raftRecovery;
 115
 116     private RaftActorSnapshotMessageSupport snapshotSupport;
 117
 118     private final BehaviorStateHolder reusableBehaviorStateHolder = new BehaviorStateHolder();
 119
 120     private final SwitchBehaviorSupplier reusableSwitchBehaviorSupplier = new SwitchBehaviorSupplier();
 121
 122     private RaftActorServerConfigurationSupport serverConfigurationSupport;
 123
 124     public RaftActor(String id, Map<String, String> peerAddresses,
 125          Optional<ConfigParams> configParams, short payloadVersion) {
 126
 127         persistentProvider = new PersistentDataProvider(this);
 128         context = new RaftActorContextImpl(this.getSelf(),
 129             this.getContext(), id, new ElectionTermImpl(persistentProvider, id, LOG),
 130             -1, -1, peerAddresses,
 131             (configParams.isPresent() ? configParams.get(): new DefaultConfigParamsImpl()),
 132             delegatingPersistenceProvider, LOG);
 133
 134         context.setPayloadVersion(payloadVersion);
 135         context.setReplicatedLog(ReplicatedLogImpl.newInstance(context, currentBehavior));
 136     }
 137
 138     @Override
 139     public void preStart() throws Exception {
 140         LOG.info("Starting recovery for {} with journal batch size {}", persistenceId(),
 141                 context.getConfigParams().getJournalRecoveryLogBatchSize());
 142
 143         super.preStart();
 144
 145         snapshotSupport = newRaftActorSnapshotMessageSupport();
 146         serverConfigurationSupport = new RaftActorServerConfigurationSupport(getRaftActorContext());
 147     }
 148
 149     @Override
 150     public void postStop() {
 151         if(currentBehavior.getDelegate() != null) {
 152             try {
 153                 currentBehavior.close();
 154             } catch (Exception e) {
 155                 LOG.debug("{}: Error closing behavior {}", persistenceId(), currentBehavior.state());
 156             }
 157         }
 158
 159         super.postStop();
 160     }
 161
 162     @Override
 163     public void handleRecover(Object message) {
 164         if(raftRecovery == null) {
 165             raftRecovery = newRaftActorRecoverySupport();
 166         }
 167
 168         boolean recoveryComplete = raftRecovery.handleRecoveryMessage(message, persistentProvider);
 169         if(recoveryComplete) {
 170             onRecoveryComplete();
 171
 172             initializeBehavior();
 173
 174             raftRecovery = null;
 175         }
 176     }
 177
 178     protected RaftActorRecoverySupport newRaftActorRecoverySupport() {
 179         return new RaftActorRecoverySupport(context, currentBehavior, getRaftActorRecoveryCohort());
 180     }
 181
 182     protected void initializeBehavior(){
 183         changeCurrentBehavior(new Follower(context));
 184     }
 185
 186     protected void changeCurrentBehavior(RaftActorBehavior newBehavior){
 187         reusableBehaviorStateHolder.init(getCurrentBehavior());
 188         setCurrentBehavior(newBehavior);
 189         handleBehaviorChange(reusableBehaviorStateHolder, getCurrentBehavior());
 190     }
 191
 192     @Override
 193     public void handleCommand(final Object message) {
 194         if(serverConfigurationSupport.handleMessage(message, this, getSender())) {
 195             return;
 196         } else if (message instanceof ApplyState){
 197             ApplyState applyState = (ApplyState) message;
 198
 199             long elapsedTime = (System.nanoTime() - applyState.getStartTime());
 200             if(elapsedTime >= APPLY_STATE_DELAY_THRESHOLD_IN_NANOS){
 201                 LOG.warn("ApplyState took more time than expected. Elapsed Time = {} ms ApplyState = {}",
 202                         TimeUnit.NANOSECONDS.toMillis(elapsedTime), applyState);
 203             }
 204
 205             if(LOG.isDebugEnabled()) {
 206                 LOG.debug("{}: Applying state for log index {} data {}",
 207                     persistenceId(), applyState.getReplicatedLogEntry().getIndex(),
 208                     applyState.getReplicatedLogEntry().getData());
 209             }
 210
 211             applyState(applyState.getClientActor(), applyState.getIdentifier(),
 212                 applyState.getReplicatedLogEntry().getData());
 213
 214             if (!hasFollowers()) {
 215                 // for single node, the capture should happen after the apply state
 216                 // as we delete messages from the persistent journal which have made it to the snapshot
 217                 // capturing the snapshot before applying makes the persistent journal and snapshot out of sync
 218                 // and recovery shows data missing
 219                 context.getReplicatedLog().captureSnapshotIfReady(applyState.getReplicatedLogEntry());
 220
 221                 context.getSnapshotManager().trimLog(context.getLastApplied(), currentBehavior);
 222             }
 223
 224         } else if (message instanceof ApplyJournalEntries){
 225             ApplyJournalEntries applyEntries = (ApplyJournalEntries) message;
 226             if(LOG.isDebugEnabled()) {
 227                 LOG.debug("{}: Persisting ApplyLogEntries with index={}", persistenceId(), applyEntries.getToIndex());
 228             }
 229
 230             persistence().persist(applyEntries, NoopProcedure.instance());
 231
 232         } else if (message instanceof FindLeader) {
 233             getSender().tell(
 234                 new FindLeaderReply(getLeaderAddress()),
 235                 getSelf()
 236             );
 237         } else if(message instanceof GetOnDemandRaftState) {
 238             onGetOnDemandRaftStats();
 239         } else if(message instanceof InitiateCaptureSnapshot) {
 240             captureSnapshot();
 241         } else if(message instanceof SwitchBehavior){
 242             switchBehavior(((SwitchBehavior) message));
 243         } else if(!snapshotSupport.handleSnapshotMessage(message)) {
 244             switchBehavior(reusableSwitchBehaviorSupplier.handleMessage(getSender(), message));
 245         }
 246     }
 247
 248     private void switchBehavior(SwitchBehavior message) {
 249         if(!getRaftActorContext().getRaftPolicy().automaticElectionsEnabled()) {
 250             RaftState newState = message.getNewState();
 251             if( newState == RaftState.Leader || newState == RaftState.Follower) {
 252                 switchBehavior(reusableSwitchBehaviorSupplier.handleMessage(getSender(), message));
 253                 getRaftActorContext().getTermInformation().updateAndPersist(message.getNewTerm(), "");
 254             } else {
 255                 LOG.warn("Switching to behavior : {} - not supported", newState);
 256             }
 257         }
 258     }
 259
 260     private void switchBehavior(Supplier<RaftActorBehavior> supplier){
 261         reusableBehaviorStateHolder.init(getCurrentBehavior());
 262
 263         setCurrentBehavior(supplier.get());
 264
 265         handleBehaviorChange(reusableBehaviorStateHolder, getCurrentBehavior());
 266     }
 267
 268     protected RaftActorSnapshotMessageSupport newRaftActorSnapshotMessageSupport() {
 269         return new RaftActorSnapshotMessageSupport(context, currentBehavior,
 270                 getRaftActorSnapshotCohort());
 271     }
 272
 273     private void onGetOnDemandRaftStats() {
 274         // Debugging message to retrieve raft stats.
 275
 276         OnDemandRaftState.Builder builder = OnDemandRaftState.builder()
 277                 .commitIndex(context.getCommitIndex())
 278                 .currentTerm(context.getTermInformation().getCurrentTerm())
 279                 .inMemoryJournalDataSize(replicatedLog().dataSize())
 280                 .inMemoryJournalLogSize(replicatedLog().size())
 281                 .isSnapshotCaptureInitiated(context.getSnapshotManager().isCapturing())
 282                 .lastApplied(context.getLastApplied())
 283                 .lastIndex(replicatedLog().lastIndex())
 284                 .lastTerm(replicatedLog().lastTerm())
 285                 .leader(getLeaderId())
 286                 .raftState(currentBehavior.state().toString())
 287                 .replicatedToAllIndex(currentBehavior.getReplicatedToAllIndex())
 288                 .snapshotIndex(replicatedLog().getSnapshotIndex())
 289                 .snapshotTerm(replicatedLog().getSnapshotTerm())
 290                 .votedFor(context.getTermInformation().getVotedFor())
 291                 .peerAddresses(context.getPeerAddresses());
 292
 293         ReplicatedLogEntry lastLogEntry = getLastLogEntry();
 294         if (lastLogEntry != null) {
 295             builder.lastLogIndex(lastLogEntry.getIndex());
 296             builder.lastLogTerm(lastLogEntry.getTerm());
 297         }
 298
 299         if(getCurrentBehavior() instanceof AbstractLeader) {
 300             AbstractLeader leader = (AbstractLeader)getCurrentBehavior();
 301             Collection<String> followerIds = leader.getFollowerIds();
 302             List<FollowerInfo> followerInfoList = Lists.newArrayListWithCapacity(followerIds.size());
 303             for(String id: followerIds) {
 304                 final FollowerLogInformation info = leader.getFollower(id);
 305                 followerInfoList.add(new FollowerInfo(id, info.getNextIndex(), info.getMatchIndex(),
 306                         info.isFollowerActive(), DurationFormatUtils.formatDurationHMS(info.timeSinceLastActivity())));
 307             }
 308
 309             builder.followerInfoList(followerInfoList);
 310         }
 311
 312         sender().tell(builder.build(), self());
 313
 314     }
 315
 316     private void handleBehaviorChange(BehaviorStateHolder oldBehaviorState, RaftActorBehavior currentBehavior) {
 317         RaftActorBehavior oldBehavior = oldBehaviorState.getBehavior();
 318
 319         if (oldBehavior != currentBehavior){
 320             onStateChanged();
 321         }
 322
 323         String lastValidLeaderId = oldBehavior == null ? null : oldBehaviorState.getLastValidLeaderId();
 324         String oldBehaviorStateName = oldBehavior == null ? null : oldBehavior.state().name();
 325
 326         // it can happen that the state has not changed but the leader has changed.
 327         Optional<ActorRef> roleChangeNotifier = getRoleChangeNotifier();
 328         if(!Objects.equal(lastValidLeaderId, currentBehavior.getLeaderId()) ||
 329            oldBehaviorState.getLeaderPayloadVersion() != currentBehavior.getLeaderPayloadVersion()) {
 330             if(roleChangeNotifier.isPresent()) {
 331                 roleChangeNotifier.get().tell(newLeaderStateChanged(getId(), currentBehavior.getLeaderId(),
 332                         currentBehavior.getLeaderPayloadVersion()), getSelf());
 333             }
 334
 335             onLeaderChanged(lastValidLeaderId, currentBehavior.getLeaderId());
 336         }
 337
 338         if (roleChangeNotifier.isPresent() &&
 339                 (oldBehavior == null || (oldBehavior.state() != currentBehavior.state()))) {
 340             roleChangeNotifier.get().tell(new RoleChanged(getId(), oldBehaviorStateName ,
 341                     currentBehavior.state().name()), getSelf());
 342         }
 343     }
 344
 345     protected LeaderStateChanged newLeaderStateChanged(String memberId, String leaderId, short leaderPayloadVersion) {
 346         return new LeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 347     }
 348
 349     @Override
 350     public long snapshotSequenceNr() {
 351         // When we do a snapshot capture, we also capture and save the sequence-number of the persistent journal,
 352         // so that we can delete the persistent journal based on the saved sequence-number
 353         // However , when akka replays the journal during recovery, it replays it from the sequence number when the snapshot
 354         // was saved and not the number we saved.
 355         // We would want to override it , by asking akka to use the last-sequence number known to us.
 356         return context.getSnapshotManager().getLastSequenceNumber();
 357     }
 358
 359     /**
 360      * When a derived RaftActor needs to persist something it must call
 361      * persistData.
 362      *
 363      * @param clientActor
 364      * @param identifier
 365      * @param data
 366      */
 367     protected void persistData(final ActorRef clientActor, final String identifier,
 368         final Payload data) {
 369
 370         ReplicatedLogEntry replicatedLogEntry = new ReplicatedLogImplEntry(
 371             context.getReplicatedLog().lastIndex() + 1,
 372             context.getTermInformation().getCurrentTerm(), data);
 373
 374         if(LOG.isDebugEnabled()) {
 375             LOG.debug("{}: Persist data {}", persistenceId(), replicatedLogEntry);
 376         }
 377
 378         final RaftActorContext raftContext = getRaftActorContext();
 379
 380         replicatedLog().appendAndPersist(replicatedLogEntry, new Procedure<ReplicatedLogEntry>() {
 381             @Override
 382             public void apply(ReplicatedLogEntry replicatedLogEntry) throws Exception {
 383                 if (!hasFollowers()){
 384                     // Increment the Commit Index and the Last Applied values
 385                     raftContext.setCommitIndex(replicatedLogEntry.getIndex());
 386                     raftContext.setLastApplied(replicatedLogEntry.getIndex());
 387
 388                     // Apply the state immediately.
 389                     self().tell(new ApplyState(clientActor, identifier, replicatedLogEntry), self());
 390
 391                     // Send a ApplyJournalEntries message so that we write the fact that we applied
 392                     // the state to durable storage
 393                     self().tell(new ApplyJournalEntries(replicatedLogEntry.getIndex()), self());
 394
 395                 } else if (clientActor != null) {
 396                     context.getReplicatedLog().captureSnapshotIfReady(replicatedLogEntry);
 397
 398                     // Send message for replication
 399                     currentBehavior.handleMessage(getSelf(),
 400                             new Replicate(clientActor, identifier, replicatedLogEntry));
 401                 }
 402             }
 403         });
 404     }
 405
 406     private ReplicatedLog replicatedLog() {
 407         return context.getReplicatedLog();
 408     }
 409
 410     protected String getId() {
 411         return context.getId();
 412     }
 413
 414     @VisibleForTesting
 415     void setCurrentBehavior(RaftActorBehavior behavior) {
 416         currentBehavior.setDelegate(behavior);
 417     }
 418
 419     protected RaftActorBehavior getCurrentBehavior() {
 420         return currentBehavior.getDelegate();
 421     }
 422
 423     /**
 424      * Derived actors can call the isLeader method to check if the current
 425      * RaftActor is the Leader or not
 426      *
 427      * @return true it this RaftActor is a Leader false otherwise
 428      */
 429     protected boolean isLeader() {
 430         return context.getId().equals(currentBehavior.getLeaderId());
 431     }
 432
 433     /**
 434      * Derived actor can call getLeader if they need a reference to the Leader.
 435      * This would be useful for example in forwarding a request to an actor
 436      * which is the leader
 437      *
 438      * @return A reference to the leader if known, null otherwise
 439      */
 440     protected ActorSelection getLeader(){
 441         String leaderAddress = getLeaderAddress();
 442
 443         if(leaderAddress == null){
 444             return null;
 445         }
 446
 447         return context.actorSelection(leaderAddress);
 448     }
 449
 450     /**
 451      *
 452      * @return the current leader's id
 453      */
 454     protected String getLeaderId(){
 455         return currentBehavior.getLeaderId();
 456     }
 457
 458     protected RaftState getRaftState() {
 459         return currentBehavior.state();
 460     }
 461
 462     protected ReplicatedLogEntry getLastLogEntry() {
 463         return replicatedLog().last();
 464     }
 465
 466     protected Long getCurrentTerm(){
 467         return context.getTermInformation().getCurrentTerm();
 468     }
 469
 470     protected Long getCommitIndex(){
 471         return context.getCommitIndex();
 472     }
 473
 474     protected Long getLastApplied(){
 475         return context.getLastApplied();
 476     }
 477
 478     protected RaftActorContext getRaftActorContext() {
 479         return context;
 480     }
 481
 482     protected void updateConfigParams(ConfigParams configParams) {
 483         context.setConfigParams(configParams);
 484     }
 485
 486     public final DataPersistenceProvider persistence() {
 487         return delegatingPersistenceProvider.getDelegate();
 488     }
 489
 490     public void setPersistence(DataPersistenceProvider provider) {
 491         delegatingPersistenceProvider.setDelegate(provider);
 492     }
 493
 494     protected void setPersistence(boolean persistent) {
 495         if(persistent) {
 496             setPersistence(new PersistentDataProvider(this));
 497         } else {
 498             setPersistence(new NonPersistentDataProvider() {
 499                 /**
 500                  * The way snapshotting works is,
 501                  * <ol>
 502                  * <li> RaftActor calls createSnapshot on the Shard
 503                  * <li> Shard sends a CaptureSnapshotReply and RaftActor then calls saveSnapshot
 504                  * <li> When saveSnapshot is invoked on the akka-persistence API it uses the SnapshotStore to save
 505                  * the snapshot. The SnapshotStore sends SaveSnapshotSuccess or SaveSnapshotFailure. When the
 506                  * RaftActor gets SaveSnapshot success it commits the snapshot to the in-memory journal. This
 507                  * commitSnapshot is mimicking what is done in SaveSnapshotSuccess.
 508                  * </ol>
 509                  */
 510                 @Override
 511                 public void saveSnapshot(Object o) {
 512                     // Make saving Snapshot successful
 513                     // Committing the snapshot here would end up calling commit in the creating state which would
 514                     // be a state violation. That's why now we send a message to commit the snapshot.
 515                     self().tell(RaftActorSnapshotMessageSupport.COMMIT_SNAPSHOT, self());
 516                 }
 517             });
 518         }
 519     }
 520
 521     /**
 522      * setPeerAddress sets the address of a known peer at a later time.
 523      * <p>
 524      * This is to account for situations where a we know that a peer
 525      * exists but we do not know an address up-front. This may also be used in
 526      * situations where a known peer starts off in a different location and we
 527      * need to change it's address
 528      * <p>
 529      * Note that if the peerId does not match the list of peers passed to
 530      * this actor during construction an IllegalStateException will be thrown.
 531      *
 532      * @param peerId
 533      * @param peerAddress
 534      */
 535     protected void setPeerAddress(String peerId, String peerAddress){
 536         context.setPeerAddress(peerId, peerAddress);
 537     }
 538
 539     /**
 540      * The applyState method will be called by the RaftActor when some data
 541      * needs to be applied to the actor's state
 542      *
 543      * @param clientActor A reference to the client who sent this message. This
 544      *                    is the same reference that was passed to persistData
 545      *                    by the derived actor. clientActor may be null when
 546      *                    the RaftActor is behaving as a follower or during
 547      *                    recovery.
 548      * @param identifier  The identifier of the persisted data. This is also
 549      *                    the same identifier that was passed to persistData by
 550      *                    the derived actor. identifier may be null when
 551      *                    the RaftActor is behaving as a follower or during
 552      *                    recovery
 553      * @param data        A piece of data that was persisted by the persistData call.
 554      *                    This should NEVER be null.
 555      */
 556     protected abstract void applyState(ActorRef clientActor, String identifier,
 557         Object data);
 558
 559     /**
 560      * Returns the RaftActorRecoveryCohort to participate in persistence recovery.
 561      */
 562     @Nonnull
 563     protected abstract RaftActorRecoveryCohort getRaftActorRecoveryCohort();
 564
 565     /**
 566      * This method is called when recovery is complete.
 567      */
 568     protected abstract void onRecoveryComplete();
 569
 570     /**
 571      * Returns the RaftActorSnapshotCohort to participate in persistence recovery.
 572      */
 573     @Nonnull
 574     protected abstract RaftActorSnapshotCohort getRaftActorSnapshotCohort();
 575
 576     /**
 577      * This method will be called by the RaftActor when the state of the
 578      * RaftActor changes. The derived actor can then use methods like
 579      * isLeader or getLeader to do something useful
 580      */
 581     protected abstract void onStateChanged();
 582
 583     /**
 584      * Notifier Actor for this RaftActor to notify when a role change happens
 585      * @return ActorRef - ActorRef of the notifier or Optional.absent if none.
 586      */
 587     protected abstract Optional<ActorRef> getRoleChangeNotifier();
 588
 589     protected void onLeaderChanged(String oldLeader, String newLeader){};
 590
 591     private String getLeaderAddress(){
 592         if(isLeader()){
 593             return getSelf().path().toString();
 594         }
 595         String leaderId = currentBehavior.getLeaderId();
 596         if (leaderId == null) {
 597             return null;
 598         }
 599         String peerAddress = context.getPeerAddress(leaderId);
 600         if(LOG.isDebugEnabled()) {
 601             LOG.debug("{}: getLeaderAddress leaderId = {} peerAddress = {}",
 602                     persistenceId(), leaderId, peerAddress);
 603         }
 604
 605         return peerAddress;
 606     }
 607
 608     protected boolean hasFollowers(){
 609         return getRaftActorContext().hasFollowers();
 610     }
 611
 612     private void captureSnapshot() {
 613         SnapshotManager snapshotManager = context.getSnapshotManager();
 614
 615         if(!snapshotManager.isCapturing()) {
 616             LOG.debug("Take a snapshot of current state. lastReplicatedLog is {} and replicatedToAllIndex is {}",
 617                 replicatedLog().last(), currentBehavior.getReplicatedToAllIndex());
 618
 619             snapshotManager.capture(replicatedLog().last(), currentBehavior.getReplicatedToAllIndex());
 620         }
 621     }
 622
 623     /**
 624      * @deprecated Deprecated in favor of {@link org.opendaylight.controller.cluster.raft.base.messages.DeleteEntries}
 625      *             whose type for fromIndex is long instead of int. This class was kept for backwards
 626      *             compatibility with Helium.
 627      */
 628     // Suppressing this warning as we can't set serialVersionUID to maintain backwards compatibility.
 629     @SuppressWarnings("serial")
 630     @Deprecated
 631     static class DeleteEntries implements Serializable {
 632         private final int fromIndex;
 633
 634         public DeleteEntries(int fromIndex) {
 635             this.fromIndex = fromIndex;
 636         }
 637
 638         public int getFromIndex() {
 639             return fromIndex;
 640         }
 641     }
 642
 643     /**
 644      * @deprecated Deprecated in favor of non-inner class {@link org.opendaylight.controller.cluster.raft.base.messages.UpdateElectionTerm}
 645      *             which has serialVersionUID set. This class was kept for backwards compatibility with Helium.
 646      */
 647     // Suppressing this warning as we can't set serialVersionUID to maintain backwards compatibility.
 648     @SuppressWarnings("serial")
 649     @Deprecated
 650     static class UpdateElectionTerm implements Serializable {
 651         private final long currentTerm;
 652         private final String votedFor;
 653
 654         public UpdateElectionTerm(long currentTerm, String votedFor) {
 655             this.currentTerm = currentTerm;
 656             this.votedFor = votedFor;
 657         }
 658
 659         public long getCurrentTerm() {
 660             return currentTerm;
 661         }
 662
 663         public String getVotedFor() {
 664             return votedFor;
 665         }
 666     }
 667
 668     private static class BehaviorStateHolder {
 669         private RaftActorBehavior behavior;
 670         private String lastValidLeaderId;
 671         private short leaderPayloadVersion;
 672
 673         void init(RaftActorBehavior behavior) {
 674             this.behavior = behavior;
 675             this.leaderPayloadVersion = behavior != null ? behavior.getLeaderPayloadVersion() : -1;
 676
 677             String behaviorLeaderId = behavior != null ? behavior.getLeaderId() : null;
 678             if(behaviorLeaderId != null) {
 679                 this.lastValidLeaderId = behaviorLeaderId;
 680             }
 681         }
 682
 683         RaftActorBehavior getBehavior() {
 684             return behavior;
 685         }
 686
 687         String getLastValidLeaderId() {
 688             return lastValidLeaderId;
 689         }
 690
 691         short getLeaderPayloadVersion() {
 692             return leaderPayloadVersion;
 693         }
 694     }
 695
 696     private class SwitchBehaviorSupplier implements Supplier<RaftActorBehavior> {
 697         private Object message;
 698         private ActorRef sender;
 699
 700         public SwitchBehaviorSupplier handleMessage(ActorRef sender, Object message){
 701             this.sender = sender;
 702             this.message = message;
 703             return this;
 704         }
 705
 706         @Override
 707         public RaftActorBehavior get() {
 708             if(this.message instanceof SwitchBehavior){
 709                 return ((SwitchBehavior) message).getNewState().createBehavior(getRaftActorContext());
 710             }
 711             return currentBehavior.handleMessage(sender, message);
 712         }
 713     }
 714 }