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.actor.PoisonPill;
  15 import com.google.common.annotations.VisibleForTesting;
  16 import com.google.common.base.Optional;
  17 import com.google.common.base.Preconditions;
  18 import com.google.common.base.Verify;
  19 import com.google.common.collect.Lists;
  20 import java.io.Serializable;
  21 import java.util.Collection;
  22 import java.util.HashMap;
  23 import java.util.List;
  24 import java.util.Map;
  25 import java.util.Objects;
  26 import java.util.concurrent.TimeUnit;
  27 import javax.annotation.Nonnull;
  28 import javax.annotation.Nullable;
  29 import org.apache.commons.lang3.time.DurationFormatUtils;
  30 import org.opendaylight.controller.cluster.DataPersistenceProvider;
  31 import org.opendaylight.controller.cluster.DelegatingPersistentDataProvider;
  32 import org.opendaylight.controller.cluster.NonPersistentDataProvider;
  33 import org.opendaylight.controller.cluster.PersistentDataProvider;
  34 import org.opendaylight.controller.cluster.common.actor.AbstractUntypedPersistentActor;
  35 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
  36 import org.opendaylight.controller.cluster.notifications.RoleChanged;
  37 import org.opendaylight.controller.cluster.raft.base.messages.ApplyJournalEntries;
  38 import org.opendaylight.controller.cluster.raft.base.messages.ApplyState;
  39 import org.opendaylight.controller.cluster.raft.base.messages.InitiateCaptureSnapshot;
  40 import org.opendaylight.controller.cluster.raft.base.messages.LeaderTransitioning;
  41 import org.opendaylight.controller.cluster.raft.base.messages.Replicate;
  42 import org.opendaylight.controller.cluster.raft.base.messages.SwitchBehavior;
  43 import org.opendaylight.controller.cluster.raft.behaviors.AbstractLeader;
  44 import org.opendaylight.controller.cluster.raft.behaviors.AbstractRaftActorBehavior;
  45 import org.opendaylight.controller.cluster.raft.behaviors.Follower;
  46 import org.opendaylight.controller.cluster.raft.behaviors.RaftActorBehavior;
  47 import org.opendaylight.controller.cluster.raft.client.messages.FindLeader;
  48 import org.opendaylight.controller.cluster.raft.client.messages.FindLeaderReply;
  49 import org.opendaylight.controller.cluster.raft.client.messages.FollowerInfo;
  50 import org.opendaylight.controller.cluster.raft.client.messages.GetOnDemandRaftState;
  51 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
  52 import org.opendaylight.controller.cluster.raft.client.messages.Shutdown;
  53 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
  54 import org.opendaylight.yangtools.concepts.Identifier;
  55 import org.opendaylight.yangtools.concepts.Immutable;
  56 import org.slf4j.Logger;
  57 import org.slf4j.LoggerFactory;
  58
  59 /**
  60  * RaftActor encapsulates a state machine that needs to be kept synchronized
  61  * in a cluster. It implements the RAFT algorithm as described in the paper
  62  * <a href='https://ramcloud.stanford.edu/wiki/download/attachments/11370504/raft.pdf'>
  63  * In Search of an Understandable Consensus Algorithm</a>
  64  * <p/>
  65  * RaftActor has 3 states and each state has a certain behavior associated
  66  * with it. A Raft actor can behave as,
  67  * <ul>
  68  * <li> A Leader </li>
  69  * <li> A Follower (or) </li>
  70  * <li> A Candidate </li>
  71  * </ul>
  72  * <p/>
  73  * <p/>
  74  * A RaftActor MUST be a Leader in order to accept requests from clients to
  75  * change the state of it's encapsulated state machine. Once a RaftActor becomes
  76  * a Leader it is also responsible for ensuring that all followers ultimately
  77  * have the same log and therefore the same state machine as itself.
  78  * <p/>
  79  * <p/>
  80  * The current behavior of a RaftActor determines how election for leadership
  81  * is initiated and how peer RaftActors react to request for votes.
  82  * <p/>
  83  * <p/>
  84  * Each RaftActor also needs to know the current election term. It uses this
  85  * information for a couple of things. One is to simply figure out who it
  86  * voted for in the last election. Another is to figure out if the message
  87  * it received to update it's state is stale.
  88  * <p/>
  89  * <p/>
  90  * The RaftActor uses akka-persistence to store it's replicated log.
  91  * Furthermore through it's behaviors a Raft Actor determines
  92  * <p/>
  93  * <ul>
  94  * <li> when a log entry should be persisted </li>
  95  * <li> when a log entry should be applied to the state machine (and) </li>
  96  * <li> when a snapshot should be saved </li>
  97  * </ul>
  98  */
  99 public abstract class RaftActor extends AbstractUntypedPersistentActor {
 100
 101     private static final long APPLY_STATE_DELAY_THRESHOLD_IN_NANOS = TimeUnit.MILLISECONDS.toNanos(50L); // 50 millis
 102
 103     protected final Logger LOG = LoggerFactory.getLogger(getClass());
 104
 105     /**
 106      * This context should NOT be passed directly to any other actor it is
 107      * only to be consumed by the RaftActorBehaviors
 108      */
 109     private final RaftActorContextImpl context;
 110
 111     private final DelegatingPersistentDataProvider delegatingPersistenceProvider;
 112
 113     private final PersistentDataProvider persistentProvider;
 114
 115     private final BehaviorStateTracker behaviorStateTracker = new BehaviorStateTracker();
 116
 117     private RaftActorRecoverySupport raftRecovery;
 118
 119     private RaftActorSnapshotMessageSupport snapshotSupport;
 120
 121     private RaftActorServerConfigurationSupport serverConfigurationSupport;
 122
 123     private RaftActorLeadershipTransferCohort leadershipTransferInProgress;
 124
 125     private boolean shuttingDown;
 126
 127     public RaftActor(String id, Map<String, String> peerAddresses,
 128          Optional<ConfigParams> configParams, short payloadVersion) {
 129
 130         persistentProvider = new PersistentDataProvider(this);
 131         delegatingPersistenceProvider = new RaftActorDelegatingPersistentDataProvider(null, persistentProvider);
 132
 133         context = new RaftActorContextImpl(this.getSelf(),
 134             this.getContext(), id, new ElectionTermImpl(persistentProvider, id, LOG),
 135             -1, -1, peerAddresses,
 136             (configParams.isPresent() ? configParams.get(): new DefaultConfigParamsImpl()),
 137             delegatingPersistenceProvider, LOG);
 138
 139         context.setPayloadVersion(payloadVersion);
 140         context.setReplicatedLog(ReplicatedLogImpl.newInstance(context));
 141     }
 142
 143     @Override
 144     public void preStart() throws Exception {
 145         LOG.info("Starting recovery for {} with journal batch size {}", persistenceId(),
 146                 context.getConfigParams().getJournalRecoveryLogBatchSize());
 147
 148         super.preStart();
 149
 150         snapshotSupport = newRaftActorSnapshotMessageSupport();
 151         serverConfigurationSupport = new RaftActorServerConfigurationSupport(this);
 152     }
 153
 154     @Override
 155     public void postStop() {
 156         context.close();
 157         super.postStop();
 158     }
 159
 160     @Override
 161     protected void handleRecover(Object message) {
 162         if(raftRecovery == null) {
 163             raftRecovery = newRaftActorRecoverySupport();
 164         }
 165
 166         boolean recoveryComplete = raftRecovery.handleRecoveryMessage(message, persistentProvider);
 167         if(recoveryComplete) {
 168             onRecoveryComplete();
 169
 170             initializeBehavior();
 171
 172             raftRecovery = null;
 173         }
 174     }
 175
 176     protected RaftActorRecoverySupport newRaftActorRecoverySupport() {
 177         return new RaftActorRecoverySupport(context, getRaftActorRecoveryCohort());
 178     }
 179
 180     @VisibleForTesting
 181     void initializeBehavior(){
 182         changeCurrentBehavior(new Follower(context));
 183     }
 184
 185     @VisibleForTesting
 186     protected void changeCurrentBehavior(RaftActorBehavior newBehavior) {
 187         final RaftActorBehavior currentBehavior = getCurrentBehavior();
 188         if (currentBehavior != null) {
 189             try {
 190                 currentBehavior.close();
 191             } catch (Exception e) {
 192                 LOG.warn("{}: Error closing behavior {}", persistence(), currentBehavior, e);
 193             }
 194         }
 195
 196         final BehaviorState state = behaviorStateTracker.capture(currentBehavior);
 197         setCurrentBehavior(newBehavior);
 198         handleBehaviorChange(state, newBehavior);
 199     }
 200
 201     /**
 202      * Method exposed for subclasses to plug-in their logic. This method is invoked by {@link #handleCommand(Object)}
 203      * for messages which are not handled by this class. Subclasses overriding this class should fall back to this
 204      * implementation for messages which they do not handle
 205      *
 206      * @param message Incoming command message
 207      */
 208     protected void handleNonRaftCommand(final Object message) {
 209         unhandled(message);
 210     }
 211
 212     /**
 213      * @deprecated This method is not final for testing purposes. DO NOT OVERRIDE IT, override
 214      * {@link #handleNonRaftCommand(Object)} instead.
 215      */
 216     @Deprecated
 217     @Override
 218     // FIXME: make this method final once our unit tests do not need to override it
 219     protected void handleCommand(final Object message) {
 220         if (serverConfigurationSupport.handleMessage(message, getSender())) {
 221             return;
 222         }
 223         if (snapshotSupport.handleSnapshotMessage(message, getSender())) {
 224             return;
 225         }
 226
 227         if (message instanceof ApplyState) {
 228             ApplyState applyState = (ApplyState) message;
 229
 230             long startTime = System.nanoTime();
 231
 232             if(LOG.isDebugEnabled()) {
 233                 LOG.debug("{}: Applying state for log index {} data {}",
 234                     persistenceId(), applyState.getReplicatedLogEntry().getIndex(),
 235                     applyState.getReplicatedLogEntry().getData());
 236             }
 237
 238             applyState(applyState.getClientActor(), applyState.getIdentifier(),
 239                 applyState.getReplicatedLogEntry().getData());
 240
 241             long elapsedTime = System.nanoTime() - startTime;
 242             if(elapsedTime >= APPLY_STATE_DELAY_THRESHOLD_IN_NANOS){
 243                 LOG.debug("ApplyState took more time than expected. Elapsed Time = {} ms ApplyState = {}",
 244                         TimeUnit.NANOSECONDS.toMillis(elapsedTime), applyState);
 245             }
 246
 247             if (!hasFollowers()) {
 248                 // for single node, the capture should happen after the apply state
 249                 // as we delete messages from the persistent journal which have made it to the snapshot
 250                 // capturing the snapshot before applying makes the persistent journal and snapshot out of sync
 251                 // and recovery shows data missing
 252                 context.getReplicatedLog().captureSnapshotIfReady(applyState.getReplicatedLogEntry());
 253
 254                 context.getSnapshotManager().trimLog(context.getLastApplied());
 255             }
 256
 257         } else if (message instanceof ApplyJournalEntries) {
 258             ApplyJournalEntries applyEntries = (ApplyJournalEntries) message;
 259             if(LOG.isDebugEnabled()) {
 260                 LOG.debug("{}: Persisting ApplyJournalEntries with index={}", persistenceId(), applyEntries.getToIndex());
 261             }
 262
 263             persistence().persist(applyEntries, NoopProcedure.instance());
 264
 265         } else if (message instanceof FindLeader) {
 266             getSender().tell(
 267                 new FindLeaderReply(getLeaderAddress()),
 268                 getSelf()
 269             );
 270         } else if(message instanceof GetOnDemandRaftState) {
 271             onGetOnDemandRaftStats();
 272         } else if(message instanceof InitiateCaptureSnapshot) {
 273             captureSnapshot();
 274         } else if(message instanceof SwitchBehavior) {
 275             switchBehavior(((SwitchBehavior) message));
 276         } else if(message instanceof LeaderTransitioning) {
 277             onLeaderTransitioning();
 278         } else if(message instanceof Shutdown) {
 279             onShutDown();
 280         } else if(message instanceof Runnable) {
 281             ((Runnable)message).run();
 282         } else {
 283             // Processing the message may affect the state, hence we need to capture it
 284             final RaftActorBehavior currentBehavior = getCurrentBehavior();
 285             final BehaviorState state = behaviorStateTracker.capture(currentBehavior);
 286
 287             // A behavior indicates that it processed the change by returning a reference to the next behavior
 288             // to be used. A null return indicates it has not processed the message and we should be passing it to
 289             // the subclass for handling.
 290             final RaftActorBehavior nextBehavior = currentBehavior.handleMessage(getSender(), message);
 291             if (nextBehavior != null) {
 292                 switchBehavior(state, nextBehavior);
 293             } else {
 294                 handleNonRaftCommand(message);
 295             }
 296         }
 297     }
 298
 299     private void initiateLeadershipTransfer(final RaftActorLeadershipTransferCohort.OnComplete onComplete) {
 300         LOG.debug("{}: Initiating leader transfer", persistenceId());
 301
 302         if(leadershipTransferInProgress == null) {
 303             leadershipTransferInProgress = new RaftActorLeadershipTransferCohort(this);
 304             leadershipTransferInProgress.addOnComplete(new RaftActorLeadershipTransferCohort.OnComplete() {
 305                 @Override
 306                 public void onSuccess(ActorRef raftActorRef) {
 307                     leadershipTransferInProgress = null;
 308                 }
 309
 310                 @Override
 311                 public void onFailure(ActorRef raftActorRef) {
 312                     leadershipTransferInProgress = null;
 313                 }
 314             });
 315
 316             leadershipTransferInProgress.addOnComplete(onComplete);
 317             leadershipTransferInProgress.init();
 318         } else {
 319             LOG.debug("{}: prior leader transfer in progress - adding callback", persistenceId());
 320             leadershipTransferInProgress.addOnComplete(onComplete);
 321         }
 322     }
 323
 324     private void onShutDown() {
 325         LOG.debug("{}: onShutDown", persistenceId());
 326
 327         if(shuttingDown) {
 328             return;
 329         }
 330
 331         shuttingDown = true;
 332
 333         final RaftActorBehavior currentBehavior = context.getCurrentBehavior();
 334         if (currentBehavior.state() != RaftState.Leader) {
 335             // For non-leaders shutdown is a no-op
 336             self().tell(PoisonPill.getInstance(), self());
 337             return;
 338         }
 339
 340         if (context.hasFollowers()) {
 341             initiateLeadershipTransfer(new RaftActorLeadershipTransferCohort.OnComplete() {
 342                 @Override
 343                 public void onSuccess(ActorRef raftActorRef) {
 344                     LOG.debug("{}: leader transfer succeeded - sending PoisonPill", persistenceId());
 345                     raftActorRef.tell(PoisonPill.getInstance(), raftActorRef);
 346                 }
 347
 348                 @Override
 349                 public void onFailure(ActorRef raftActorRef) {
 350                     LOG.debug("{}: leader transfer failed - sending PoisonPill", persistenceId());
 351                     raftActorRef.tell(PoisonPill.getInstance(), raftActorRef);
 352                 }
 353             });
 354         } else {
 355             pauseLeader(new TimedRunnable(context.getConfigParams().getElectionTimeOutInterval(), this) {
 356                 @Override
 357                 protected void doRun() {
 358                     self().tell(PoisonPill.getInstance(), self());
 359                 }
 360
 361                 @Override
 362                 protected void doCancel() {
 363                     self().tell(PoisonPill.getInstance(), self());
 364                 }
 365             });
 366         }
 367     }
 368
 369     private void onLeaderTransitioning() {
 370         LOG.debug("{}: onLeaderTransitioning", persistenceId());
 371         Optional<ActorRef> roleChangeNotifier = getRoleChangeNotifier();
 372         if(getRaftState() == RaftState.Follower && roleChangeNotifier.isPresent()) {
 373             roleChangeNotifier.get().tell(newLeaderStateChanged(getId(), null,
 374                 getCurrentBehavior().getLeaderPayloadVersion()), getSelf());
 375         }
 376     }
 377
 378     private void switchBehavior(SwitchBehavior message) {
 379         if(!getRaftActorContext().getRaftPolicy().automaticElectionsEnabled()) {
 380             RaftState newState = message.getNewState();
 381             if( newState == RaftState.Leader || newState == RaftState.Follower) {
 382                 switchBehavior(behaviorStateTracker.capture(getCurrentBehavior()),
 383                     AbstractRaftActorBehavior.createBehavior(context, message.getNewState()));
 384                 getRaftActorContext().getTermInformation().updateAndPersist(message.getNewTerm(), "");
 385             } else {
 386                 LOG.warn("Switching to behavior : {} - not supported", newState);
 387             }
 388         }
 389     }
 390
 391     private void switchBehavior(final BehaviorState oldBehaviorState, final RaftActorBehavior nextBehavior) {
 392         setCurrentBehavior(nextBehavior);
 393         handleBehaviorChange(oldBehaviorState, nextBehavior);
 394     }
 395
 396     @VisibleForTesting
 397     RaftActorSnapshotMessageSupport newRaftActorSnapshotMessageSupport() {
 398         return new RaftActorSnapshotMessageSupport(context, getRaftActorSnapshotCohort());
 399     }
 400
 401     private void onGetOnDemandRaftStats() {
 402         // Debugging message to retrieve raft stats.
 403
 404         Map<String, String> peerAddresses = new HashMap<>();
 405         Map<String, Boolean> peerVotingStates = new HashMap<>();
 406         for(PeerInfo info: context.getPeers()) {
 407             peerVotingStates.put(info.getId(), info.isVoting());
 408             peerAddresses.put(info.getId(), info.getAddress() != null ? info.getAddress() : "");
 409         }
 410
 411         final RaftActorBehavior currentBehavior = context.getCurrentBehavior();
 412         OnDemandRaftState.Builder builder = OnDemandRaftState.builder()
 413                 .commitIndex(context.getCommitIndex())
 414                 .currentTerm(context.getTermInformation().getCurrentTerm())
 415                 .inMemoryJournalDataSize(replicatedLog().dataSize())
 416                 .inMemoryJournalLogSize(replicatedLog().size())
 417                 .isSnapshotCaptureInitiated(context.getSnapshotManager().isCapturing())
 418                 .lastApplied(context.getLastApplied())
 419                 .lastIndex(replicatedLog().lastIndex())
 420                 .lastTerm(replicatedLog().lastTerm())
 421                 .leader(getLeaderId())
 422                 .raftState(currentBehavior.state().toString())
 423                 .replicatedToAllIndex(currentBehavior.getReplicatedToAllIndex())
 424                 .snapshotIndex(replicatedLog().getSnapshotIndex())
 425                 .snapshotTerm(replicatedLog().getSnapshotTerm())
 426                 .votedFor(context.getTermInformation().getVotedFor())
 427                 .isVoting(context.isVotingMember())
 428                 .peerAddresses(peerAddresses)
 429                 .peerVotingStates(peerVotingStates)
 430                 .customRaftPolicyClassName(context.getConfigParams().getCustomRaftPolicyImplementationClass());
 431
 432         ReplicatedLogEntry lastLogEntry = replicatedLog().last();
 433         if (lastLogEntry != null) {
 434             builder.lastLogIndex(lastLogEntry.getIndex());
 435             builder.lastLogTerm(lastLogEntry.getTerm());
 436         }
 437
 438         if(getCurrentBehavior() instanceof AbstractLeader) {
 439             AbstractLeader leader = (AbstractLeader)getCurrentBehavior();
 440             Collection<String> followerIds = leader.getFollowerIds();
 441             List<FollowerInfo> followerInfoList = Lists.newArrayListWithCapacity(followerIds.size());
 442             for(String id: followerIds) {
 443                 final FollowerLogInformation info = leader.getFollower(id);
 444                 followerInfoList.add(new FollowerInfo(id, info.getNextIndex(), info.getMatchIndex(),
 445                         info.isFollowerActive(), DurationFormatUtils.formatDurationHMS(info.timeSinceLastActivity()),
 446                         context.getPeerInfo(info.getId()).isVoting()));
 447             }
 448
 449             builder.followerInfoList(followerInfoList);
 450         }
 451
 452         sender().tell(builder.build(), self());
 453
 454     }
 455
 456     private void handleBehaviorChange(BehaviorState oldBehaviorState, RaftActorBehavior currentBehavior) {
 457         RaftActorBehavior oldBehavior = oldBehaviorState.getBehavior();
 458
 459         if (oldBehavior != currentBehavior){
 460             onStateChanged();
 461         }
 462
 463         String lastValidLeaderId = oldBehavior == null ? null : oldBehaviorState.getLastValidLeaderId();
 464         String oldBehaviorStateName = oldBehavior == null ? null : oldBehavior.state().name();
 465
 466         // it can happen that the state has not changed but the leader has changed.
 467         Optional<ActorRef> roleChangeNotifier = getRoleChangeNotifier();
 468         if(!Objects.equals(lastValidLeaderId, currentBehavior.getLeaderId()) ||
 469            oldBehaviorState.getLeaderPayloadVersion() != currentBehavior.getLeaderPayloadVersion()) {
 470             if(roleChangeNotifier.isPresent()) {
 471                 roleChangeNotifier.get().tell(newLeaderStateChanged(getId(), currentBehavior.getLeaderId(),
 472                         currentBehavior.getLeaderPayloadVersion()), getSelf());
 473             }
 474
 475             onLeaderChanged(lastValidLeaderId, currentBehavior.getLeaderId());
 476
 477             if(leadershipTransferInProgress != null) {
 478                 leadershipTransferInProgress.onNewLeader(currentBehavior.getLeaderId());
 479             }
 480
 481             serverConfigurationSupport.onNewLeader(currentBehavior.getLeaderId());
 482         }
 483
 484         if (roleChangeNotifier.isPresent() &&
 485                 (oldBehavior == null || (oldBehavior.state() != currentBehavior.state()))) {
 486             roleChangeNotifier.get().tell(new RoleChanged(getId(), oldBehaviorStateName ,
 487                     currentBehavior.state().name()), getSelf());
 488         }
 489     }
 490
 491     protected LeaderStateChanged newLeaderStateChanged(String memberId, String leaderId, short leaderPayloadVersion) {
 492         return new LeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
 493     }
 494
 495     @Override
 496     public long snapshotSequenceNr() {
 497         // When we do a snapshot capture, we also capture and save the sequence-number of the persistent journal,
 498         // so that we can delete the persistent journal based on the saved sequence-number
 499         // However , when akka replays the journal during recovery, it replays it from the sequence number when the snapshot
 500         // was saved and not the number we saved.
 501         // We would want to override it , by asking akka to use the last-sequence number known to us.
 502         return context.getSnapshotManager().getLastSequenceNumber();
 503     }
 504
 505     /**
 506      * When a derived RaftActor needs to persist something it must call
 507      * persistData.
 508      *
 509      * @param clientActor
 510      * @param identifier
 511      * @param data
 512      */
 513     protected final void persistData(final ActorRef clientActor, final Identifier identifier, final Payload data) {
 514
 515         ReplicatedLogEntry replicatedLogEntry = new ReplicatedLogImplEntry(
 516             context.getReplicatedLog().lastIndex() + 1,
 517             context.getTermInformation().getCurrentTerm(), data);
 518
 519         if(LOG.isDebugEnabled()) {
 520             LOG.debug("{}: Persist data {}", persistenceId(), replicatedLogEntry);
 521         }
 522
 523         final RaftActorContext raftContext = getRaftActorContext();
 524
 525         replicatedLog().appendAndPersist(replicatedLogEntry, replicatedLogEntry1 -> {
 526             if (!hasFollowers()){
 527                 // Increment the Commit Index and the Last Applied values
 528                 raftContext.setCommitIndex(replicatedLogEntry1.getIndex());
 529                 raftContext.setLastApplied(replicatedLogEntry1.getIndex());
 530
 531                 // Apply the state immediately.
 532                 self().tell(new ApplyState(clientActor, identifier, replicatedLogEntry1), self());
 533
 534                 // Send a ApplyJournalEntries message so that we write the fact that we applied
 535                 // the state to durable storage
 536                 self().tell(new ApplyJournalEntries(replicatedLogEntry1.getIndex()), self());
 537
 538             } else if (clientActor != null) {
 539                 context.getReplicatedLog().captureSnapshotIfReady(replicatedLogEntry1);
 540
 541                 // Send message for replication
 542                 getCurrentBehavior().handleMessage(getSelf(),
 543                         new Replicate(clientActor, identifier, replicatedLogEntry1));
 544             }
 545         });
 546     }
 547
 548     private ReplicatedLog replicatedLog() {
 549         return context.getReplicatedLog();
 550     }
 551
 552     protected String getId() {
 553         return context.getId();
 554     }
 555
 556     @VisibleForTesting
 557     void setCurrentBehavior(RaftActorBehavior behavior) {
 558         context.setCurrentBehavior(behavior);
 559     }
 560
 561     protected RaftActorBehavior getCurrentBehavior() {
 562         return context.getCurrentBehavior();
 563     }
 564
 565     /**
 566      * Derived actors can call the isLeader method to check if the current
 567      * RaftActor is the Leader or not
 568      *
 569      * @return true it this RaftActor is a Leader false otherwise
 570      */
 571     protected boolean isLeader() {
 572         return context.getId().equals(getCurrentBehavior().getLeaderId());
 573     }
 574
 575     protected final boolean isLeaderActive() {
 576         return getRaftState() != RaftState.IsolatedLeader && !shuttingDown &&
 577                 !isLeadershipTransferInProgress();
 578     }
 579
 580     private boolean isLeadershipTransferInProgress() {
 581         return leadershipTransferInProgress != null && leadershipTransferInProgress.isTransferring();
 582     }
 583
 584     /**
 585      * Derived actor can call getLeader if they need a reference to the Leader.
 586      * This would be useful for example in forwarding a request to an actor
 587      * which is the leader
 588      *
 589      * @return A reference to the leader if known, null otherwise
 590      */
 591     protected ActorSelection getLeader(){
 592         String leaderAddress = getLeaderAddress();
 593
 594         if(leaderAddress == null){
 595             return null;
 596         }
 597
 598         return context.actorSelection(leaderAddress);
 599     }
 600
 601     /**
 602      *
 603      * @return the current leader's id
 604      */
 605     protected final String getLeaderId(){
 606         return getCurrentBehavior().getLeaderId();
 607     }
 608
 609     @VisibleForTesting
 610     protected final RaftState getRaftState() {
 611         return getCurrentBehavior().state();
 612     }
 613
 614     protected Long getCurrentTerm(){
 615         return context.getTermInformation().getCurrentTerm();
 616     }
 617
 618     protected RaftActorContext getRaftActorContext() {
 619         return context;
 620     }
 621
 622     protected void updateConfigParams(ConfigParams configParams) {
 623
 624         // obtain the RaftPolicy for oldConfigParams and the updated one.
 625         String oldRaftPolicy = context.getConfigParams().
 626             getCustomRaftPolicyImplementationClass();
 627         String newRaftPolicy = configParams.
 628             getCustomRaftPolicyImplementationClass();
 629
 630         LOG.debug("{}: RaftPolicy used with prev.config {}, RaftPolicy used with newConfig {}", persistenceId(),
 631             oldRaftPolicy, newRaftPolicy);
 632         context.setConfigParams(configParams);
 633         if (!Objects.equals(oldRaftPolicy, newRaftPolicy)) {
 634             // The RaftPolicy was modified. If the current behavior is Follower then re-initialize to Follower
 635             // but transfer the previous leaderId so it doesn't immediately try to schedule an election. This
 636             // avoids potential disruption. Otherwise, switch to Follower normally.
 637             RaftActorBehavior behavior = getCurrentBehavior();
 638             if (behavior != null && behavior.state() == RaftState.Follower) {
 639                 String previousLeaderId = behavior.getLeaderId();
 640                 short previousLeaderPayloadVersion = behavior.getLeaderPayloadVersion();
 641
 642                 LOG.debug("{}: Re-initializing to Follower with previous leaderId {}", persistenceId(), previousLeaderId);
 643
 644                 changeCurrentBehavior(new Follower(context, previousLeaderId, previousLeaderPayloadVersion));
 645             } else {
 646                 initializeBehavior();
 647             }
 648         }
 649     }
 650
 651     public final DataPersistenceProvider persistence() {
 652         return delegatingPersistenceProvider.getDelegate();
 653     }
 654
 655     public void setPersistence(DataPersistenceProvider provider) {
 656         delegatingPersistenceProvider.setDelegate(provider);
 657     }
 658
 659     protected void setPersistence(boolean persistent) {
 660         if(persistent) {
 661             setPersistence(new PersistentDataProvider(this));
 662         } else {
 663             setPersistence(new NonPersistentDataProvider() {
 664                 /**
 665                  * The way snapshotting works is,
 666                  * <ol>
 667                  * <li> RaftActor calls createSnapshot on the Shard
 668                  * <li> Shard sends a CaptureSnapshotReply and RaftActor then calls saveSnapshot
 669                  * <li> When saveSnapshot is invoked on the akka-persistence API it uses the SnapshotStore to save
 670                  * the snapshot. The SnapshotStore sends SaveSnapshotSuccess or SaveSnapshotFailure. When the
 671                  * RaftActor gets SaveSnapshot success it commits the snapshot to the in-memory journal. This
 672                  * commitSnapshot is mimicking what is done in SaveSnapshotSuccess.
 673                  * </ol>
 674                  */
 675                 @Override
 676                 public void saveSnapshot(Object o) {
 677                     // Make saving Snapshot successful
 678                     // Committing the snapshot here would end up calling commit in the creating state which would
 679                     // be a state violation. That's why now we send a message to commit the snapshot.
 680                     self().tell(RaftActorSnapshotMessageSupport.COMMIT_SNAPSHOT, self());
 681                 }
 682             });
 683         }
 684     }
 685
 686     /**
 687      * setPeerAddress sets the address of a known peer at a later time.
 688      * <p>
 689      * This is to account for situations where a we know that a peer
 690      * exists but we do not know an address up-front. This may also be used in
 691      * situations where a known peer starts off in a different location and we
 692      * need to change it's address
 693      * <p>
 694      * Note that if the peerId does not match the list of peers passed to
 695      * this actor during construction an IllegalStateException will be thrown.
 696      *
 697      * @param peerId
 698      * @param peerAddress
 699      */
 700     protected void setPeerAddress(String peerId, String peerAddress){
 701         context.setPeerAddress(peerId, peerAddress);
 702     }
 703
 704     /**
 705      * The applyState method will be called by the RaftActor when some data
 706      * needs to be applied to the actor's state
 707      *
 708      * @param clientActor A reference to the client who sent this message. This
 709      *                    is the same reference that was passed to persistData
 710      *                    by the derived actor. clientActor may be null when
 711      *                    the RaftActor is behaving as a follower or during
 712      *                    recovery.
 713      * @param identifier  The identifier of the persisted data. This is also
 714      *                    the same identifier that was passed to persistData by
 715      *                    the derived actor. identifier may be null when
 716      *                    the RaftActor is behaving as a follower or during
 717      *                    recovery
 718      * @param data        A piece of data that was persisted by the persistData call.
 719      *                    This should NEVER be null.
 720      */
 721     protected abstract void applyState(ActorRef clientActor, Identifier identifier, Object data);
 722
 723     /**
 724      * Returns the RaftActorRecoveryCohort to participate in persistence recovery.
 725      */
 726     @Nonnull
 727     protected abstract RaftActorRecoveryCohort getRaftActorRecoveryCohort();
 728
 729     /**
 730      * This method is called when recovery is complete.
 731      */
 732     protected abstract void onRecoveryComplete();
 733
 734     /**
 735      * Returns the RaftActorSnapshotCohort to participate in persistence recovery.
 736      */
 737     @Nonnull
 738     protected abstract RaftActorSnapshotCohort getRaftActorSnapshotCohort();
 739
 740     /**
 741      * This method will be called by the RaftActor when the state of the
 742      * RaftActor changes. The derived actor can then use methods like
 743      * isLeader or getLeader to do something useful
 744      */
 745     protected abstract void onStateChanged();
 746
 747     /**
 748      * Notifier Actor for this RaftActor to notify when a role change happens
 749      * @return ActorRef - ActorRef of the notifier or Optional.absent if none.
 750      */
 751     protected abstract Optional<ActorRef> getRoleChangeNotifier();
 752
 753     /**
 754      * This method is called prior to operations such as leadership transfer and actor shutdown when the leader
 755      * must pause or stop its duties. This method allows derived classes to gracefully pause or finish current
 756      * work prior to performing the operation. On completion of any work, the run method must be called on the
 757      * given Runnable to proceed with the given operation. <b>Important:</b> the run method must be called on
 758      * this actor's thread dispatcher as as it modifies internal state.
 759      * <p>
 760      * The default implementation immediately runs the operation.
 761      *
 762      * @param operation the operation to run
 763      */
 764     protected void pauseLeader(Runnable operation) {
 765         operation.run();
 766     }
 767
 768     protected void onLeaderChanged(String oldLeader, String newLeader) {
 769
 770     };
 771
 772     private String getLeaderAddress(){
 773         if(isLeader()){
 774             return getSelf().path().toString();
 775         }
 776         String leaderId = getLeaderId();
 777         if (leaderId == null) {
 778             return null;
 779         }
 780         String peerAddress = context.getPeerAddress(leaderId);
 781         if(LOG.isDebugEnabled()) {
 782             LOG.debug("{}: getLeaderAddress leaderId = {} peerAddress = {}",
 783                     persistenceId(), leaderId, peerAddress);
 784         }
 785
 786         return peerAddress;
 787     }
 788
 789     protected boolean hasFollowers(){
 790         return getRaftActorContext().hasFollowers();
 791     }
 792
 793     private void captureSnapshot() {
 794         SnapshotManager snapshotManager = context.getSnapshotManager();
 795
 796         if (!snapshotManager.isCapturing()) {
 797             final long idx = getCurrentBehavior().getReplicatedToAllIndex();
 798             LOG.debug("Take a snapshot of current state. lastReplicatedLog is {} and replicatedToAllIndex is {}",
 799                 replicatedLog().last(), idx);
 800
 801             snapshotManager.capture(replicatedLog().last(), idx);
 802         }
 803     }
 804
 805     /**
 806      * Switch this member to non-voting status. This is a no-op for all behaviors except when we are the leader,
 807      * in which case we need to step down.
 808      */
 809     void becomeNonVoting() {
 810         if (isLeader()) {
 811             initiateLeadershipTransfer(new RaftActorLeadershipTransferCohort.OnComplete() {
 812                 @Override
 813                 public void onSuccess(ActorRef raftActorRef) {
 814                     LOG.debug("{}: leader transfer succeeded after change to non-voting", persistenceId());
 815                     ensureFollowerState();
 816                 }
 817
 818                 @Override
 819                 public void onFailure(ActorRef raftActorRef) {
 820                     LOG.debug("{}: leader transfer failed after change to non-voting", persistenceId());
 821                     ensureFollowerState();
 822                 }
 823
 824                 private void ensureFollowerState() {
 825                     // Whether or not leadership transfer succeeded, we have to step down as leader and
 826                     // switch to Follower so ensure that.
 827                     if (getRaftState() != RaftState.Follower) {
 828                         initializeBehavior();
 829                     }
 830                 }
 831             });
 832         }
 833     }
 834
 835     /**
 836      * @deprecated Deprecated in favor of {@link org.opendaylight.controller.cluster.raft.base.messages.DeleteEntries}
 837      *             whose type for fromIndex is long instead of int. This class was kept for backwards
 838      *             compatibility with Helium.
 839      */
 840     // Suppressing this warning as we can't set serialVersionUID to maintain backwards compatibility.
 841     @SuppressWarnings("serial")
 842     @Deprecated
 843     static class DeleteEntries implements Serializable {
 844         private final int fromIndex;
 845
 846         public DeleteEntries(int fromIndex) {
 847             this.fromIndex = fromIndex;
 848         }
 849
 850         public int getFromIndex() {
 851             return fromIndex;
 852         }
 853     }
 854
 855     /**
 856      * @deprecated Deprecated in favor of non-inner class {@link org.opendaylight.controller.cluster.raft.base.messages.UpdateElectionTerm}
 857      *             which has serialVersionUID set. This class was kept for backwards compatibility with Helium.
 858      */
 859     // Suppressing this warning as we can't set serialVersionUID to maintain backwards compatibility.
 860     @SuppressWarnings("serial")
 861     @Deprecated
 862     static class UpdateElectionTerm implements Serializable {
 863         private final long currentTerm;
 864         private final String votedFor;
 865
 866         public UpdateElectionTerm(long currentTerm, String votedFor) {
 867             this.currentTerm = currentTerm;
 868             this.votedFor = votedFor;
 869         }
 870
 871         public long getCurrentTerm() {
 872             return currentTerm;
 873         }
 874
 875         public String getVotedFor() {
 876             return votedFor;
 877         }
 878     }
 879
 880     /**
 881      * A point-in-time capture of {@link RaftActorBehavior} state critical for transitioning between behaviors.
 882      */
 883     private static abstract class BehaviorState implements Immutable {
 884         @Nullable abstract RaftActorBehavior getBehavior();
 885         @Nullable abstract String getLastValidLeaderId();
 886         @Nullable abstract short getLeaderPayloadVersion();
 887     }
 888
 889     /**
 890      * A {@link BehaviorState} corresponding to non-null {@link RaftActorBehavior} state.
 891      */
 892     private static final class SimpleBehaviorState extends BehaviorState {
 893         private final RaftActorBehavior behavior;
 894         private final String lastValidLeaderId;
 895         private final short leaderPayloadVersion;
 896
 897         SimpleBehaviorState(final String lastValidLeaderId, final RaftActorBehavior behavior) {
 898             this.lastValidLeaderId = lastValidLeaderId;
 899             this.behavior = Preconditions.checkNotNull(behavior);
 900             this.leaderPayloadVersion = behavior.getLeaderPayloadVersion();
 901         }
 902
 903         @Override
 904         RaftActorBehavior getBehavior() {
 905             return behavior;
 906         }
 907
 908         @Override
 909         String getLastValidLeaderId() {
 910             return lastValidLeaderId;
 911         }
 912
 913         @Override
 914         short getLeaderPayloadVersion() {
 915             return leaderPayloadVersion;
 916         }
 917     }
 918
 919     /**
 920      * Class tracking behavior-related information, which we need to keep around and pass across behavior switches.
 921      * An instance is created for each RaftActor. It has two functions:
 922      * - it keeps track of the last leader ID we have encountered since we have been created
 923      * - it creates state capture needed to transition from one behavior to the next
 924      */
 925     private static final class BehaviorStateTracker {
 926         /**
 927          * A {@link BehaviorState} corresponding to null {@link RaftActorBehavior} state. Since null behavior is only
 928          * allowed before we receive the first message, we know the leader ID to be null.
 929          */
 930         private static final BehaviorState NULL_BEHAVIOR_STATE = new BehaviorState() {
 931             @Override
 932             RaftActorBehavior getBehavior() {
 933                 return null;
 934             }
 935
 936             @Override
 937             String getLastValidLeaderId() {
 938                 return null;
 939             }
 940
 941             @Override
 942             short getLeaderPayloadVersion() {
 943                 return -1;
 944             }
 945         };
 946
 947         private String lastValidLeaderId;
 948
 949         BehaviorState capture(final RaftActorBehavior behavior) {
 950             if (behavior == null) {
 951                 Verify.verify(lastValidLeaderId == null, "Null behavior with non-null last leader");
 952                 return NULL_BEHAVIOR_STATE;
 953             }
 954
 955             final String leaderId = behavior.getLeaderId();
 956             if (leaderId != null) {
 957                 lastValidLeaderId = leaderId;
 958             }
 959
 960             return new SimpleBehaviorState(lastValidLeaderId, behavior);
 961         }
 962     }
 963
 964 }