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.
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
10 package org.opendaylight.controller.cluster.raft;
12 import akka.actor.ActorRef;
13 import akka.actor.ActorSelection;
14 import akka.actor.PoisonPill;
15 import akka.japi.Procedure;
16 import com.google.common.annotations.VisibleForTesting;
17 import com.google.common.base.Objects;
18 import com.google.common.base.Optional;
19 import com.google.common.base.Supplier;
20 import com.google.common.collect.Lists;
21 import java.io.Serializable;
22 import java.util.Collection;
23 import java.util.HashMap;
24 import java.util.List;
26 import java.util.concurrent.TimeUnit;
27 import javax.annotation.Nonnull;
28 import org.apache.commons.lang3.time.DurationFormatUtils;
29 import org.opendaylight.controller.cluster.DataPersistenceProvider;
30 import org.opendaylight.controller.cluster.DelegatingPersistentDataProvider;
31 import org.opendaylight.controller.cluster.NonPersistentDataProvider;
32 import org.opendaylight.controller.cluster.PersistentDataProvider;
33 import org.opendaylight.controller.cluster.common.actor.AbstractUntypedPersistentActor;
34 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
35 import org.opendaylight.controller.cluster.notifications.RoleChanged;
36 import org.opendaylight.controller.cluster.raft.base.messages.ApplyJournalEntries;
37 import org.opendaylight.controller.cluster.raft.base.messages.ApplyState;
38 import org.opendaylight.controller.cluster.raft.base.messages.InitiateCaptureSnapshot;
39 import org.opendaylight.controller.cluster.raft.base.messages.LeaderTransitioning;
40 import org.opendaylight.controller.cluster.raft.base.messages.Replicate;
41 import org.opendaylight.controller.cluster.raft.base.messages.SwitchBehavior;
42 import org.opendaylight.controller.cluster.raft.behaviors.AbstractLeader;
43 import org.opendaylight.controller.cluster.raft.behaviors.AbstractRaftActorBehavior;
44 import org.opendaylight.controller.cluster.raft.behaviors.DelegatingRaftActorBehavior;
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.slf4j.Logger;
55 import org.slf4j.LoggerFactory;
58 * RaftActor encapsulates a state machine that needs to be kept synchronized
59 * in a cluster. It implements the RAFT algorithm as described in the paper
60 * <a href='https://ramcloud.stanford.edu/wiki/download/attachments/11370504/raft.pdf'>
61 * In Search of an Understandable Consensus Algorithm</a>
63 * RaftActor has 3 states and each state has a certain behavior associated
64 * with it. A Raft actor can behave as,
67 * <li> A Follower (or) </li>
68 * <li> A Candidate </li>
72 * A RaftActor MUST be a Leader in order to accept requests from clients to
73 * change the state of it's encapsulated state machine. Once a RaftActor becomes
74 * a Leader it is also responsible for ensuring that all followers ultimately
75 * have the same log and therefore the same state machine as itself.
78 * The current behavior of a RaftActor determines how election for leadership
79 * is initiated and how peer RaftActors react to request for votes.
82 * Each RaftActor also needs to know the current election term. It uses this
83 * information for a couple of things. One is to simply figure out who it
84 * voted for in the last election. Another is to figure out if the message
85 * it received to update it's state is stale.
88 * The RaftActor uses akka-persistence to store it's replicated log.
89 * Furthermore through it's behaviors a Raft Actor determines
92 * <li> when a log entry should be persisted </li>
93 * <li> when a log entry should be applied to the state machine (and) </li>
94 * <li> when a snapshot should be saved </li>
97 public abstract class RaftActor extends AbstractUntypedPersistentActor {
99 private static final long APPLY_STATE_DELAY_THRESHOLD_IN_NANOS = TimeUnit.MILLISECONDS.toNanos(50L); // 50 millis
101 protected final Logger LOG = LoggerFactory.getLogger(getClass());
104 * The current state determines the current behavior of a RaftActor
105 * A Raft Actor always starts off in the Follower State
107 private final DelegatingRaftActorBehavior currentBehavior = new DelegatingRaftActorBehavior();
110 * This context should NOT be passed directly to any other actor it is
111 * only to be consumed by the RaftActorBehaviors
113 private final RaftActorContextImpl context;
115 private final DelegatingPersistentDataProvider delegatingPersistenceProvider;
117 private final PersistentDataProvider persistentProvider;
119 private RaftActorRecoverySupport raftRecovery;
121 private RaftActorSnapshotMessageSupport snapshotSupport;
123 private final BehaviorStateHolder reusableBehaviorStateHolder = new BehaviorStateHolder();
125 private final SwitchBehaviorSupplier reusableSwitchBehaviorSupplier = new SwitchBehaviorSupplier();
127 private RaftActorServerConfigurationSupport serverConfigurationSupport;
129 private RaftActorLeadershipTransferCohort leadershipTransferInProgress;
131 private boolean shuttingDown;
133 public RaftActor(String id, Map<String, String> peerAddresses,
134 Optional<ConfigParams> configParams, short payloadVersion) {
136 persistentProvider = new PersistentDataProvider(this);
137 delegatingPersistenceProvider = new RaftActorDelegatingPersistentDataProvider(null, persistentProvider);
139 context = new RaftActorContextImpl(this.getSelf(),
140 this.getContext(), id, new ElectionTermImpl(persistentProvider, id, LOG),
141 -1, -1, peerAddresses,
142 (configParams.isPresent() ? configParams.get(): new DefaultConfigParamsImpl()),
143 delegatingPersistenceProvider, LOG);
145 context.setPayloadVersion(payloadVersion);
146 context.setReplicatedLog(ReplicatedLogImpl.newInstance(context, currentBehavior));
150 public void preStart() throws Exception {
151 LOG.info("Starting recovery for {} with journal batch size {}", persistenceId(),
152 context.getConfigParams().getJournalRecoveryLogBatchSize());
156 snapshotSupport = newRaftActorSnapshotMessageSupport();
157 serverConfigurationSupport = new RaftActorServerConfigurationSupport(this);
161 public void postStop() {
162 if(currentBehavior.getDelegate() != null) {
164 currentBehavior.close();
165 } catch (Exception e) {
166 LOG.debug("{}: Error closing behavior {}", persistenceId(), currentBehavior.state());
174 protected void handleRecover(Object message) {
175 if(raftRecovery == null) {
176 raftRecovery = newRaftActorRecoverySupport();
179 boolean recoveryComplete = raftRecovery.handleRecoveryMessage(message, persistentProvider);
180 if(recoveryComplete) {
181 onRecoveryComplete();
183 initializeBehavior();
187 if (context.getReplicatedLog().size() > 0) {
188 self().tell(new InitiateCaptureSnapshot(), self());
189 LOG.info("{}: Snapshot capture initiated after recovery", persistenceId());
191 LOG.info("{}: Snapshot capture NOT initiated after recovery, journal empty", persistenceId());
196 protected RaftActorRecoverySupport newRaftActorRecoverySupport() {
197 return new RaftActorRecoverySupport(context, currentBehavior, getRaftActorRecoveryCohort());
200 protected void initializeBehavior(){
201 changeCurrentBehavior(new Follower(context));
204 protected void changeCurrentBehavior(RaftActorBehavior newBehavior){
205 if(getCurrentBehavior() != null) {
207 getCurrentBehavior().close();
208 } catch(Exception e) {
209 LOG.warn("{}: Error closing behavior {}", persistence(), getCurrentBehavior(), e);
213 reusableBehaviorStateHolder.init(getCurrentBehavior());
214 setCurrentBehavior(newBehavior);
215 handleBehaviorChange(reusableBehaviorStateHolder, getCurrentBehavior());
219 protected void handleCommand(final Object message) {
220 if (serverConfigurationSupport.handleMessage(message, getSender())) {
223 if (snapshotSupport.handleSnapshotMessage(message, getSender())) {
227 if (message instanceof ApplyState) {
228 ApplyState applyState = (ApplyState) message;
230 long elapsedTime = (System.nanoTime() - applyState.getStartTime());
231 if(elapsedTime >= APPLY_STATE_DELAY_THRESHOLD_IN_NANOS){
232 LOG.warn("ApplyState took more time than expected. Elapsed Time = {} ms ApplyState = {}",
233 TimeUnit.NANOSECONDS.toMillis(elapsedTime), applyState);
236 if(LOG.isDebugEnabled()) {
237 LOG.debug("{}: Applying state for log index {} data {}",
238 persistenceId(), applyState.getReplicatedLogEntry().getIndex(),
239 applyState.getReplicatedLogEntry().getData());
242 applyState(applyState.getClientActor(), applyState.getIdentifier(),
243 applyState.getReplicatedLogEntry().getData());
245 if (!hasFollowers()) {
246 // for single node, the capture should happen after the apply state
247 // as we delete messages from the persistent journal which have made it to the snapshot
248 // capturing the snapshot before applying makes the persistent journal and snapshot out of sync
249 // and recovery shows data missing
250 context.getReplicatedLog().captureSnapshotIfReady(applyState.getReplicatedLogEntry());
252 context.getSnapshotManager().trimLog(context.getLastApplied(), currentBehavior);
255 } else if (message instanceof ApplyJournalEntries) {
256 ApplyJournalEntries applyEntries = (ApplyJournalEntries) message;
257 if(LOG.isDebugEnabled()) {
258 LOG.debug("{}: Persisting ApplyJournalEntries with index={}", persistenceId(), applyEntries.getToIndex());
261 persistence().persist(applyEntries, NoopProcedure.instance());
263 } else if (message instanceof FindLeader) {
265 new FindLeaderReply(getLeaderAddress()),
268 } else if(message instanceof GetOnDemandRaftState) {
269 onGetOnDemandRaftStats();
270 } else if(message instanceof InitiateCaptureSnapshot) {
272 } else if(message instanceof SwitchBehavior) {
273 switchBehavior(((SwitchBehavior) message));
274 } else if(message instanceof LeaderTransitioning) {
275 onLeaderTransitioning();
276 } else if(message instanceof Shutdown) {
278 } else if(message instanceof Runnable) {
279 ((Runnable)message).run();
281 switchBehavior(reusableSwitchBehaviorSupplier.handleMessage(getSender(), message));
285 void initiateLeadershipTransfer(final RaftActorLeadershipTransferCohort.OnComplete onComplete) {
286 LOG.debug("{}: Initiating leader transfer", persistenceId());
288 if(leadershipTransferInProgress == null) {
289 leadershipTransferInProgress = new RaftActorLeadershipTransferCohort(this, getSender());
290 leadershipTransferInProgress.addOnComplete(new RaftActorLeadershipTransferCohort.OnComplete() {
292 public void onSuccess(ActorRef raftActorRef, ActorRef replyTo) {
293 leadershipTransferInProgress = null;
297 public void onFailure(ActorRef raftActorRef, ActorRef replyTo) {
298 leadershipTransferInProgress = null;
302 leadershipTransferInProgress.addOnComplete(onComplete);
303 leadershipTransferInProgress.init();
305 LOG.debug("{}: prior leader transfer in progress - adding callback", persistenceId());
306 leadershipTransferInProgress.addOnComplete(onComplete);
310 private void onShutDown() {
311 LOG.debug("{}: onShutDown", persistenceId());
318 if(currentBehavior.state() == RaftState.Leader && context.hasFollowers()) {
319 initiateLeadershipTransfer(new RaftActorLeadershipTransferCohort.OnComplete() {
321 public void onSuccess(ActorRef raftActorRef, ActorRef replyTo) {
322 LOG.debug("{}: leader transfer succeeded - sending PoisonPill", persistenceId());
323 raftActorRef.tell(PoisonPill.getInstance(), raftActorRef);
327 public void onFailure(ActorRef raftActorRef, ActorRef replyTo) {
328 LOG.debug("{}: leader transfer failed - sending PoisonPill", persistenceId());
329 raftActorRef.tell(PoisonPill.getInstance(), raftActorRef);
332 } else if(currentBehavior.state() == RaftState.Leader) {
333 pauseLeader(new TimedRunnable(context.getConfigParams().getElectionTimeOutInterval(), this) {
335 protected void doRun() {
336 self().tell(PoisonPill.getInstance(), self());
340 protected void doCancel() {
341 self().tell(PoisonPill.getInstance(), self());
345 self().tell(PoisonPill.getInstance(), self());
349 private void onLeaderTransitioning() {
350 LOG.debug("{}: onLeaderTransitioning", persistenceId());
351 Optional<ActorRef> roleChangeNotifier = getRoleChangeNotifier();
352 if(currentBehavior.state() == RaftState.Follower && roleChangeNotifier.isPresent()) {
353 roleChangeNotifier.get().tell(newLeaderStateChanged(getId(), null,
354 currentBehavior.getLeaderPayloadVersion()), getSelf());
358 private void switchBehavior(SwitchBehavior message) {
359 if(!getRaftActorContext().getRaftPolicy().automaticElectionsEnabled()) {
360 RaftState newState = message.getNewState();
361 if( newState == RaftState.Leader || newState == RaftState.Follower) {
362 switchBehavior(reusableSwitchBehaviorSupplier.handleMessage(getSender(), message));
363 getRaftActorContext().getTermInformation().updateAndPersist(message.getNewTerm(), "");
365 LOG.warn("Switching to behavior : {} - not supported", newState);
370 private void switchBehavior(Supplier<RaftActorBehavior> supplier){
371 reusableBehaviorStateHolder.init(getCurrentBehavior());
373 setCurrentBehavior(supplier.get());
375 handleBehaviorChange(reusableBehaviorStateHolder, getCurrentBehavior());
378 protected RaftActorSnapshotMessageSupport newRaftActorSnapshotMessageSupport() {
379 return new RaftActorSnapshotMessageSupport(context, currentBehavior,
380 getRaftActorSnapshotCohort());
383 private void onGetOnDemandRaftStats() {
384 // Debugging message to retrieve raft stats.
386 Map<String, String> peerAddresses = new HashMap<>();
387 for(String peerId: context.getPeerIds()) {
388 peerAddresses.put(peerId, context.getPeerAddress(peerId));
391 OnDemandRaftState.Builder builder = OnDemandRaftState.builder()
392 .commitIndex(context.getCommitIndex())
393 .currentTerm(context.getTermInformation().getCurrentTerm())
394 .inMemoryJournalDataSize(replicatedLog().dataSize())
395 .inMemoryJournalLogSize(replicatedLog().size())
396 .isSnapshotCaptureInitiated(context.getSnapshotManager().isCapturing())
397 .lastApplied(context.getLastApplied())
398 .lastIndex(replicatedLog().lastIndex())
399 .lastTerm(replicatedLog().lastTerm())
400 .leader(getLeaderId())
401 .raftState(currentBehavior.state().toString())
402 .replicatedToAllIndex(currentBehavior.getReplicatedToAllIndex())
403 .snapshotIndex(replicatedLog().getSnapshotIndex())
404 .snapshotTerm(replicatedLog().getSnapshotTerm())
405 .votedFor(context.getTermInformation().getVotedFor())
406 .peerAddresses(peerAddresses)
407 .customRaftPolicyClassName(context.getConfigParams().getCustomRaftPolicyImplementationClass());
409 ReplicatedLogEntry lastLogEntry = getLastLogEntry();
410 if (lastLogEntry != null) {
411 builder.lastLogIndex(lastLogEntry.getIndex());
412 builder.lastLogTerm(lastLogEntry.getTerm());
415 if(getCurrentBehavior() instanceof AbstractLeader) {
416 AbstractLeader leader = (AbstractLeader)getCurrentBehavior();
417 Collection<String> followerIds = leader.getFollowerIds();
418 List<FollowerInfo> followerInfoList = Lists.newArrayListWithCapacity(followerIds.size());
419 for(String id: followerIds) {
420 final FollowerLogInformation info = leader.getFollower(id);
421 followerInfoList.add(new FollowerInfo(id, info.getNextIndex(), info.getMatchIndex(),
422 info.isFollowerActive(), DurationFormatUtils.formatDurationHMS(info.timeSinceLastActivity())));
425 builder.followerInfoList(followerInfoList);
428 sender().tell(builder.build(), self());
432 private void handleBehaviorChange(BehaviorStateHolder oldBehaviorState, RaftActorBehavior currentBehavior) {
433 RaftActorBehavior oldBehavior = oldBehaviorState.getBehavior();
435 if (oldBehavior != currentBehavior){
439 String lastValidLeaderId = oldBehavior == null ? null : oldBehaviorState.getLastValidLeaderId();
440 String oldBehaviorStateName = oldBehavior == null ? null : oldBehavior.state().name();
442 // it can happen that the state has not changed but the leader has changed.
443 Optional<ActorRef> roleChangeNotifier = getRoleChangeNotifier();
444 if(!Objects.equal(lastValidLeaderId, currentBehavior.getLeaderId()) ||
445 oldBehaviorState.getLeaderPayloadVersion() != currentBehavior.getLeaderPayloadVersion()) {
446 if(roleChangeNotifier.isPresent()) {
447 roleChangeNotifier.get().tell(newLeaderStateChanged(getId(), currentBehavior.getLeaderId(),
448 currentBehavior.getLeaderPayloadVersion()), getSelf());
451 onLeaderChanged(lastValidLeaderId, currentBehavior.getLeaderId());
453 if(leadershipTransferInProgress != null) {
454 leadershipTransferInProgress.onNewLeader(currentBehavior.getLeaderId());
457 serverConfigurationSupport.onNewLeader(currentBehavior.getLeaderId());
460 if (roleChangeNotifier.isPresent() &&
461 (oldBehavior == null || (oldBehavior.state() != currentBehavior.state()))) {
462 roleChangeNotifier.get().tell(new RoleChanged(getId(), oldBehaviorStateName ,
463 currentBehavior.state().name()), getSelf());
467 protected LeaderStateChanged newLeaderStateChanged(String memberId, String leaderId, short leaderPayloadVersion) {
468 return new LeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
472 public long snapshotSequenceNr() {
473 // When we do a snapshot capture, we also capture and save the sequence-number of the persistent journal,
474 // so that we can delete the persistent journal based on the saved sequence-number
475 // However , when akka replays the journal during recovery, it replays it from the sequence number when the snapshot
476 // was saved and not the number we saved.
477 // We would want to override it , by asking akka to use the last-sequence number known to us.
478 return context.getSnapshotManager().getLastSequenceNumber();
482 * When a derived RaftActor needs to persist something it must call
489 protected void persistData(final ActorRef clientActor, final String identifier,
490 final Payload data) {
492 ReplicatedLogEntry replicatedLogEntry = new ReplicatedLogImplEntry(
493 context.getReplicatedLog().lastIndex() + 1,
494 context.getTermInformation().getCurrentTerm(), data);
496 if(LOG.isDebugEnabled()) {
497 LOG.debug("{}: Persist data {}", persistenceId(), replicatedLogEntry);
500 final RaftActorContext raftContext = getRaftActorContext();
502 replicatedLog().appendAndPersist(replicatedLogEntry, new Procedure<ReplicatedLogEntry>() {
504 public void apply(ReplicatedLogEntry replicatedLogEntry) {
505 if (!hasFollowers()){
506 // Increment the Commit Index and the Last Applied values
507 raftContext.setCommitIndex(replicatedLogEntry.getIndex());
508 raftContext.setLastApplied(replicatedLogEntry.getIndex());
510 // Apply the state immediately.
511 self().tell(new ApplyState(clientActor, identifier, replicatedLogEntry), self());
513 // Send a ApplyJournalEntries message so that we write the fact that we applied
514 // the state to durable storage
515 self().tell(new ApplyJournalEntries(replicatedLogEntry.getIndex()), self());
517 } else if (clientActor != null) {
518 context.getReplicatedLog().captureSnapshotIfReady(replicatedLogEntry);
520 // Send message for replication
521 currentBehavior.handleMessage(getSelf(),
522 new Replicate(clientActor, identifier, replicatedLogEntry));
528 private ReplicatedLog replicatedLog() {
529 return context.getReplicatedLog();
532 protected String getId() {
533 return context.getId();
537 void setCurrentBehavior(RaftActorBehavior behavior) {
538 currentBehavior.setDelegate(behavior);
541 protected RaftActorBehavior getCurrentBehavior() {
542 return currentBehavior.getDelegate();
546 * Derived actors can call the isLeader method to check if the current
547 * RaftActor is the Leader or not
549 * @return true it this RaftActor is a Leader false otherwise
551 protected boolean isLeader() {
552 return context.getId().equals(currentBehavior.getLeaderId());
555 protected boolean isLeaderActive() {
556 return currentBehavior.state() != RaftState.IsolatedLeader && !shuttingDown &&
557 !isLeadershipTransferInProgress();
560 private boolean isLeadershipTransferInProgress() {
561 return leadershipTransferInProgress != null && leadershipTransferInProgress.isTransferring();
565 * Derived actor can call getLeader if they need a reference to the Leader.
566 * This would be useful for example in forwarding a request to an actor
567 * which is the leader
569 * @return A reference to the leader if known, null otherwise
571 protected ActorSelection getLeader(){
572 String leaderAddress = getLeaderAddress();
574 if(leaderAddress == null){
578 return context.actorSelection(leaderAddress);
583 * @return the current leader's id
585 protected String getLeaderId(){
586 return currentBehavior.getLeaderId();
589 protected RaftState getRaftState() {
590 return currentBehavior.state();
593 protected ReplicatedLogEntry getLastLogEntry() {
594 return replicatedLog().last();
597 protected Long getCurrentTerm(){
598 return context.getTermInformation().getCurrentTerm();
601 protected Long getCommitIndex(){
602 return context.getCommitIndex();
605 protected Long getLastApplied(){
606 return context.getLastApplied();
609 protected RaftActorContext getRaftActorContext() {
613 protected void updateConfigParams(ConfigParams configParams) {
615 // obtain the RaftPolicy for oldConfigParams and the updated one.
616 String oldRaftPolicy = context.getConfigParams().
617 getCustomRaftPolicyImplementationClass();
618 String newRaftPolicy = configParams.
619 getCustomRaftPolicyImplementationClass();
621 LOG.debug("{}: RaftPolicy used with prev.config {}, RaftPolicy used with newConfig {}", persistenceId(),
622 oldRaftPolicy, newRaftPolicy);
623 context.setConfigParams(configParams);
624 if (!Objects.equal(oldRaftPolicy, newRaftPolicy)) {
625 // The RaftPolicy was modified. If the current behavior is Follower then re-initialize to Follower
626 // but transfer the previous leaderId so it doesn't immediately try to schedule an election. This
627 // avoids potential disruption. Otherwise, switch to Follower normally.
628 RaftActorBehavior behavior = currentBehavior.getDelegate();
629 if(behavior instanceof Follower) {
630 String previousLeaderId = ((Follower)behavior).getLeaderId();
631 short previousLeaderPayloadVersion = behavior.getLeaderPayloadVersion();
633 LOG.debug("{}: Re-initializing to Follower with previous leaderId {}", persistenceId(), previousLeaderId);
635 changeCurrentBehavior(new Follower(context, previousLeaderId, previousLeaderPayloadVersion));
637 initializeBehavior();
642 public final DataPersistenceProvider persistence() {
643 return delegatingPersistenceProvider.getDelegate();
646 public void setPersistence(DataPersistenceProvider provider) {
647 delegatingPersistenceProvider.setDelegate(provider);
650 protected void setPersistence(boolean persistent) {
652 setPersistence(new PersistentDataProvider(this));
654 setPersistence(new NonPersistentDataProvider() {
656 * The way snapshotting works is,
658 * <li> RaftActor calls createSnapshot on the Shard
659 * <li> Shard sends a CaptureSnapshotReply and RaftActor then calls saveSnapshot
660 * <li> When saveSnapshot is invoked on the akka-persistence API it uses the SnapshotStore to save
661 * the snapshot. The SnapshotStore sends SaveSnapshotSuccess or SaveSnapshotFailure. When the
662 * RaftActor gets SaveSnapshot success it commits the snapshot to the in-memory journal. This
663 * commitSnapshot is mimicking what is done in SaveSnapshotSuccess.
667 public void saveSnapshot(Object o) {
668 // Make saving Snapshot successful
669 // Committing the snapshot here would end up calling commit in the creating state which would
670 // be a state violation. That's why now we send a message to commit the snapshot.
671 self().tell(RaftActorSnapshotMessageSupport.COMMIT_SNAPSHOT, self());
678 * setPeerAddress sets the address of a known peer at a later time.
680 * This is to account for situations where a we know that a peer
681 * exists but we do not know an address up-front. This may also be used in
682 * situations where a known peer starts off in a different location and we
683 * need to change it's address
685 * Note that if the peerId does not match the list of peers passed to
686 * this actor during construction an IllegalStateException will be thrown.
691 protected void setPeerAddress(String peerId, String peerAddress){
692 context.setPeerAddress(peerId, peerAddress);
696 * The applyState method will be called by the RaftActor when some data
697 * needs to be applied to the actor's state
699 * @param clientActor A reference to the client who sent this message. This
700 * is the same reference that was passed to persistData
701 * by the derived actor. clientActor may be null when
702 * the RaftActor is behaving as a follower or during
704 * @param identifier The identifier of the persisted data. This is also
705 * the same identifier that was passed to persistData by
706 * the derived actor. identifier may be null when
707 * the RaftActor is behaving as a follower or during
709 * @param data A piece of data that was persisted by the persistData call.
710 * This should NEVER be null.
712 protected abstract void applyState(ActorRef clientActor, String identifier,
716 * Returns the RaftActorRecoveryCohort to participate in persistence recovery.
719 protected abstract RaftActorRecoveryCohort getRaftActorRecoveryCohort();
722 * This method is called when recovery is complete.
724 protected abstract void onRecoveryComplete();
727 * Returns the RaftActorSnapshotCohort to participate in persistence recovery.
730 protected abstract RaftActorSnapshotCohort getRaftActorSnapshotCohort();
733 * This method will be called by the RaftActor when the state of the
734 * RaftActor changes. The derived actor can then use methods like
735 * isLeader or getLeader to do something useful
737 protected abstract void onStateChanged();
740 * Notifier Actor for this RaftActor to notify when a role change happens
741 * @return ActorRef - ActorRef of the notifier or Optional.absent if none.
743 protected abstract Optional<ActorRef> getRoleChangeNotifier();
746 * This method is called prior to operations such as leadership transfer and actor shutdown when the leader
747 * must pause or stop its duties. This method allows derived classes to gracefully pause or finish current
748 * work prior to performing the operation. On completion of any work, the run method must be called on the
749 * given Runnable to proceed with the given operation. <b>Important:</b> the run method must be called on
750 * this actor's thread dispatcher as as it modifies internal state.
752 * The default implementation immediately runs the operation.
754 * @param operation the operation to run
756 protected void pauseLeader(Runnable operation) {
760 protected void onLeaderChanged(String oldLeader, String newLeader){};
762 private String getLeaderAddress(){
764 return getSelf().path().toString();
766 String leaderId = currentBehavior.getLeaderId();
767 if (leaderId == null) {
770 String peerAddress = context.getPeerAddress(leaderId);
771 if(LOG.isDebugEnabled()) {
772 LOG.debug("{}: getLeaderAddress leaderId = {} peerAddress = {}",
773 persistenceId(), leaderId, peerAddress);
779 protected boolean hasFollowers(){
780 return getRaftActorContext().hasFollowers();
783 private void captureSnapshot() {
784 SnapshotManager snapshotManager = context.getSnapshotManager();
786 if(!snapshotManager.isCapturing()) {
787 LOG.debug("Take a snapshot of current state. lastReplicatedLog is {} and replicatedToAllIndex is {}",
788 replicatedLog().last(), currentBehavior.getReplicatedToAllIndex());
790 snapshotManager.capture(replicatedLog().last(), currentBehavior.getReplicatedToAllIndex());
795 * @deprecated Deprecated in favor of {@link org.opendaylight.controller.cluster.raft.base.messages.DeleteEntries}
796 * whose type for fromIndex is long instead of int. This class was kept for backwards
797 * compatibility with Helium.
799 // Suppressing this warning as we can't set serialVersionUID to maintain backwards compatibility.
800 @SuppressWarnings("serial")
802 static class DeleteEntries implements Serializable {
803 private final int fromIndex;
805 public DeleteEntries(int fromIndex) {
806 this.fromIndex = fromIndex;
809 public int getFromIndex() {
815 * @deprecated Deprecated in favor of non-inner class {@link org.opendaylight.controller.cluster.raft.base.messages.UpdateElectionTerm}
816 * which has serialVersionUID set. This class was kept for backwards compatibility with Helium.
818 // Suppressing this warning as we can't set serialVersionUID to maintain backwards compatibility.
819 @SuppressWarnings("serial")
821 static class UpdateElectionTerm implements Serializable {
822 private final long currentTerm;
823 private final String votedFor;
825 public UpdateElectionTerm(long currentTerm, String votedFor) {
826 this.currentTerm = currentTerm;
827 this.votedFor = votedFor;
830 public long getCurrentTerm() {
834 public String getVotedFor() {
839 private static class BehaviorStateHolder {
840 private RaftActorBehavior behavior;
841 private String lastValidLeaderId;
842 private short leaderPayloadVersion;
844 void init(RaftActorBehavior behavior) {
845 this.behavior = behavior;
846 this.leaderPayloadVersion = behavior != null ? behavior.getLeaderPayloadVersion() : -1;
848 String behaviorLeaderId = behavior != null ? behavior.getLeaderId() : null;
849 if(behaviorLeaderId != null) {
850 this.lastValidLeaderId = behaviorLeaderId;
854 RaftActorBehavior getBehavior() {
858 String getLastValidLeaderId() {
859 return lastValidLeaderId;
862 short getLeaderPayloadVersion() {
863 return leaderPayloadVersion;
867 private class SwitchBehaviorSupplier implements Supplier<RaftActorBehavior> {
868 private Object message;
869 private ActorRef sender;
871 public SwitchBehaviorSupplier handleMessage(ActorRef sender, Object message){
872 this.sender = sender;
873 this.message = message;
878 public RaftActorBehavior get() {
879 if(this.message instanceof SwitchBehavior){
880 return AbstractRaftActorBehavior.createBehavior(context, ((SwitchBehavior) message).getNewState());
882 return currentBehavior.handleMessage(sender, message);