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 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;
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;
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>
65 * RaftActor has 3 states and each state has a certain behavior associated
66 * with it. A Raft actor can behave as,
69 * <li> A Follower (or) </li>
70 * <li> A Candidate </li>
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.
80 * The current behavior of a RaftActor determines how election for leadership
81 * is initiated and how peer RaftActors react to request for votes.
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.
90 * The RaftActor uses akka-persistence to store it's replicated log.
91 * Furthermore through it's behaviors a Raft Actor determines
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>
99 public abstract class RaftActor extends AbstractUntypedPersistentActor {
101 private static final long APPLY_STATE_DELAY_THRESHOLD_IN_NANOS = TimeUnit.MILLISECONDS.toNanos(50L); // 50 millis
103 protected final Logger LOG = LoggerFactory.getLogger(getClass());
106 * This context should NOT be passed directly to any other actor it is
107 * only to be consumed by the RaftActorBehaviors
109 private final RaftActorContextImpl context;
111 private final DelegatingPersistentDataProvider delegatingPersistenceProvider;
113 private final PersistentDataProvider persistentProvider;
115 private final BehaviorStateTracker behaviorStateTracker = new BehaviorStateTracker();
117 private RaftActorRecoverySupport raftRecovery;
119 private RaftActorSnapshotMessageSupport snapshotSupport;
121 private RaftActorServerConfigurationSupport serverConfigurationSupport;
123 private RaftActorLeadershipTransferCohort leadershipTransferInProgress;
125 private boolean shuttingDown;
127 public RaftActor(String id, Map<String, String> peerAddresses,
128 Optional<ConfigParams> configParams, short payloadVersion) {
130 persistentProvider = new PersistentDataProvider(this);
131 delegatingPersistenceProvider = new RaftActorDelegatingPersistentDataProvider(null, persistentProvider);
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);
139 context.setPayloadVersion(payloadVersion);
140 context.setReplicatedLog(ReplicatedLogImpl.newInstance(context));
144 public void preStart() throws Exception {
145 LOG.info("Starting recovery for {} with journal batch size {}", persistenceId(),
146 context.getConfigParams().getJournalRecoveryLogBatchSize());
150 snapshotSupport = newRaftActorSnapshotMessageSupport();
151 serverConfigurationSupport = new RaftActorServerConfigurationSupport(this);
155 public void postStop() {
161 protected void handleRecover(Object message) {
162 if(raftRecovery == null) {
163 raftRecovery = newRaftActorRecoverySupport();
166 boolean recoveryComplete = raftRecovery.handleRecoveryMessage(message, persistentProvider);
167 if(recoveryComplete) {
168 onRecoveryComplete();
170 initializeBehavior();
176 protected RaftActorRecoverySupport newRaftActorRecoverySupport() {
177 return new RaftActorRecoverySupport(context, getRaftActorRecoveryCohort());
181 void initializeBehavior(){
182 changeCurrentBehavior(new Follower(context));
186 protected void changeCurrentBehavior(RaftActorBehavior newBehavior) {
187 final RaftActorBehavior currentBehavior = getCurrentBehavior();
188 if (currentBehavior != null) {
190 currentBehavior.close();
191 } catch (Exception e) {
192 LOG.warn("{}: Error closing behavior {}", persistence(), currentBehavior, e);
196 final BehaviorState state = behaviorStateTracker.capture(currentBehavior);
197 setCurrentBehavior(newBehavior);
198 handleBehaviorChange(state, newBehavior);
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
206 * @param message Incoming command message
208 protected void handleNonRaftCommand(final Object message) {
213 * @deprecated This method is not final for testing purposes. DO NOT OVERRIDE IT, override
214 * {@link #handleNonRaftCommand(Object)} instead.
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())) {
223 if (snapshotSupport.handleSnapshotMessage(message, getSender())) {
227 if (message instanceof ApplyState) {
228 ApplyState applyState = (ApplyState) message;
230 long startTime = System.nanoTime();
232 if(LOG.isDebugEnabled()) {
233 LOG.debug("{}: Applying state for log index {} data {}",
234 persistenceId(), applyState.getReplicatedLogEntry().getIndex(),
235 applyState.getReplicatedLogEntry().getData());
238 applyState(applyState.getClientActor(), applyState.getIdentifier(),
239 applyState.getReplicatedLogEntry().getData());
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);
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());
254 context.getSnapshotManager().trimLog(context.getLastApplied());
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());
263 persistence().persist(applyEntries, NoopProcedure.instance());
265 } else if (message instanceof FindLeader) {
267 new FindLeaderReply(getLeaderAddress()),
270 } else if(message instanceof GetOnDemandRaftState) {
271 onGetOnDemandRaftStats();
272 } else if(message instanceof InitiateCaptureSnapshot) {
274 } else if(message instanceof SwitchBehavior) {
275 switchBehavior(((SwitchBehavior) message));
276 } else if(message instanceof LeaderTransitioning) {
277 onLeaderTransitioning();
278 } else if(message instanceof Shutdown) {
280 } else if(message instanceof Runnable) {
281 ((Runnable)message).run();
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);
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);
294 handleNonRaftCommand(message);
299 private void initiateLeadershipTransfer(final RaftActorLeadershipTransferCohort.OnComplete onComplete) {
300 LOG.debug("{}: Initiating leader transfer", persistenceId());
302 if(leadershipTransferInProgress == null) {
303 leadershipTransferInProgress = new RaftActorLeadershipTransferCohort(this);
304 leadershipTransferInProgress.addOnComplete(new RaftActorLeadershipTransferCohort.OnComplete() {
306 public void onSuccess(ActorRef raftActorRef) {
307 leadershipTransferInProgress = null;
311 public void onFailure(ActorRef raftActorRef) {
312 leadershipTransferInProgress = null;
316 leadershipTransferInProgress.addOnComplete(onComplete);
317 leadershipTransferInProgress.init();
319 LOG.debug("{}: prior leader transfer in progress - adding callback", persistenceId());
320 leadershipTransferInProgress.addOnComplete(onComplete);
324 private void onShutDown() {
325 LOG.debug("{}: onShutDown", persistenceId());
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());
340 if (context.hasFollowers()) {
341 initiateLeadershipTransfer(new RaftActorLeadershipTransferCohort.OnComplete() {
343 public void onSuccess(ActorRef raftActorRef) {
344 LOG.debug("{}: leader transfer succeeded - sending PoisonPill", persistenceId());
345 raftActorRef.tell(PoisonPill.getInstance(), raftActorRef);
349 public void onFailure(ActorRef raftActorRef) {
350 LOG.debug("{}: leader transfer failed - sending PoisonPill", persistenceId());
351 raftActorRef.tell(PoisonPill.getInstance(), raftActorRef);
355 pauseLeader(new TimedRunnable(context.getConfigParams().getElectionTimeOutInterval(), this) {
357 protected void doRun() {
358 self().tell(PoisonPill.getInstance(), self());
362 protected void doCancel() {
363 self().tell(PoisonPill.getInstance(), self());
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());
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(), "");
386 LOG.warn("Switching to behavior : {} - not supported", newState);
391 private void switchBehavior(final BehaviorState oldBehaviorState, final RaftActorBehavior nextBehavior) {
392 setCurrentBehavior(nextBehavior);
393 handleBehaviorChange(oldBehaviorState, nextBehavior);
397 RaftActorSnapshotMessageSupport newRaftActorSnapshotMessageSupport() {
398 return new RaftActorSnapshotMessageSupport(context, getRaftActorSnapshotCohort());
401 private void onGetOnDemandRaftStats() {
402 // Debugging message to retrieve raft stats.
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() : "");
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());
432 ReplicatedLogEntry lastLogEntry = replicatedLog().last();
433 if (lastLogEntry != null) {
434 builder.lastLogIndex(lastLogEntry.getIndex());
435 builder.lastLogTerm(lastLogEntry.getTerm());
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()));
449 builder.followerInfoList(followerInfoList);
452 sender().tell(builder.build(), self());
456 private void handleBehaviorChange(BehaviorState oldBehaviorState, RaftActorBehavior currentBehavior) {
457 RaftActorBehavior oldBehavior = oldBehaviorState.getBehavior();
459 if (oldBehavior != currentBehavior){
463 String lastValidLeaderId = oldBehavior == null ? null : oldBehaviorState.getLastValidLeaderId();
464 String oldBehaviorStateName = oldBehavior == null ? null : oldBehavior.state().name();
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());
475 onLeaderChanged(lastValidLeaderId, currentBehavior.getLeaderId());
477 if(leadershipTransferInProgress != null) {
478 leadershipTransferInProgress.onNewLeader(currentBehavior.getLeaderId());
481 serverConfigurationSupport.onNewLeader(currentBehavior.getLeaderId());
484 if (roleChangeNotifier.isPresent() &&
485 (oldBehavior == null || (oldBehavior.state() != currentBehavior.state()))) {
486 roleChangeNotifier.get().tell(new RoleChanged(getId(), oldBehaviorStateName ,
487 currentBehavior.state().name()), getSelf());
491 protected LeaderStateChanged newLeaderStateChanged(String memberId, String leaderId, short leaderPayloadVersion) {
492 return new LeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
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();
506 * When a derived RaftActor needs to persist something it must call
513 protected final void persistData(final ActorRef clientActor, final Identifier identifier, final Payload data) {
515 ReplicatedLogEntry replicatedLogEntry = new ReplicatedLogImplEntry(
516 context.getReplicatedLog().lastIndex() + 1,
517 context.getTermInformation().getCurrentTerm(), data);
519 if(LOG.isDebugEnabled()) {
520 LOG.debug("{}: Persist data {}", persistenceId(), replicatedLogEntry);
523 final RaftActorContext raftContext = getRaftActorContext();
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());
531 // Apply the state immediately.
532 self().tell(new ApplyState(clientActor, identifier, replicatedLogEntry1), self());
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());
538 } else if (clientActor != null) {
539 context.getReplicatedLog().captureSnapshotIfReady(replicatedLogEntry1);
541 // Send message for replication
542 getCurrentBehavior().handleMessage(getSelf(),
543 new Replicate(clientActor, identifier, replicatedLogEntry1));
548 private ReplicatedLog replicatedLog() {
549 return context.getReplicatedLog();
552 protected String getId() {
553 return context.getId();
557 void setCurrentBehavior(RaftActorBehavior behavior) {
558 context.setCurrentBehavior(behavior);
561 protected RaftActorBehavior getCurrentBehavior() {
562 return context.getCurrentBehavior();
566 * Derived actors can call the isLeader method to check if the current
567 * RaftActor is the Leader or not
569 * @return true it this RaftActor is a Leader false otherwise
571 protected boolean isLeader() {
572 return context.getId().equals(getCurrentBehavior().getLeaderId());
575 protected final boolean isLeaderActive() {
576 return getRaftState() != RaftState.IsolatedLeader && !shuttingDown &&
577 !isLeadershipTransferInProgress();
580 private boolean isLeadershipTransferInProgress() {
581 return leadershipTransferInProgress != null && leadershipTransferInProgress.isTransferring();
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
589 * @return A reference to the leader if known, null otherwise
591 protected ActorSelection getLeader(){
592 String leaderAddress = getLeaderAddress();
594 if(leaderAddress == null){
598 return context.actorSelection(leaderAddress);
603 * @return the current leader's id
605 protected final String getLeaderId(){
606 return getCurrentBehavior().getLeaderId();
610 protected final RaftState getRaftState() {
611 return getCurrentBehavior().state();
614 protected Long getCurrentTerm(){
615 return context.getTermInformation().getCurrentTerm();
618 protected RaftActorContext getRaftActorContext() {
622 protected void updateConfigParams(ConfigParams configParams) {
624 // obtain the RaftPolicy for oldConfigParams and the updated one.
625 String oldRaftPolicy = context.getConfigParams().
626 getCustomRaftPolicyImplementationClass();
627 String newRaftPolicy = configParams.
628 getCustomRaftPolicyImplementationClass();
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();
642 LOG.debug("{}: Re-initializing to Follower with previous leaderId {}", persistenceId(), previousLeaderId);
644 changeCurrentBehavior(new Follower(context, previousLeaderId, previousLeaderPayloadVersion));
646 initializeBehavior();
651 public final DataPersistenceProvider persistence() {
652 return delegatingPersistenceProvider.getDelegate();
655 public void setPersistence(DataPersistenceProvider provider) {
656 delegatingPersistenceProvider.setDelegate(provider);
659 protected void setPersistence(boolean persistent) {
661 setPersistence(new PersistentDataProvider(this));
663 setPersistence(new NonPersistentDataProvider() {
665 * The way snapshotting works is,
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.
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());
687 * setPeerAddress sets the address of a known peer at a later time.
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
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.
700 protected void setPeerAddress(String peerId, String peerAddress){
701 context.setPeerAddress(peerId, peerAddress);
705 * The applyState method will be called by the RaftActor when some data
706 * needs to be applied to the actor's state
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
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
718 * @param data A piece of data that was persisted by the persistData call.
719 * This should NEVER be null.
721 protected abstract void applyState(ActorRef clientActor, Identifier identifier, Object data);
724 * Returns the RaftActorRecoveryCohort to participate in persistence recovery.
727 protected abstract RaftActorRecoveryCohort getRaftActorRecoveryCohort();
730 * This method is called when recovery is complete.
732 protected abstract void onRecoveryComplete();
735 * Returns the RaftActorSnapshotCohort to participate in persistence recovery.
738 protected abstract RaftActorSnapshotCohort getRaftActorSnapshotCohort();
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
745 protected abstract void onStateChanged();
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.
751 protected abstract Optional<ActorRef> getRoleChangeNotifier();
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.
760 * The default implementation immediately runs the operation.
762 * @param operation the operation to run
764 protected void pauseLeader(Runnable operation) {
768 protected void onLeaderChanged(String oldLeader, String newLeader) {
772 private String getLeaderAddress(){
774 return getSelf().path().toString();
776 String leaderId = getLeaderId();
777 if (leaderId == null) {
780 String peerAddress = context.getPeerAddress(leaderId);
781 if(LOG.isDebugEnabled()) {
782 LOG.debug("{}: getLeaderAddress leaderId = {} peerAddress = {}",
783 persistenceId(), leaderId, peerAddress);
789 protected boolean hasFollowers(){
790 return getRaftActorContext().hasFollowers();
793 private void captureSnapshot() {
794 SnapshotManager snapshotManager = context.getSnapshotManager();
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);
801 snapshotManager.capture(replicatedLog().last(), idx);
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.
809 void becomeNonVoting() {
811 initiateLeadershipTransfer(new RaftActorLeadershipTransferCohort.OnComplete() {
813 public void onSuccess(ActorRef raftActorRef) {
814 LOG.debug("{}: leader transfer succeeded after change to non-voting", persistenceId());
815 ensureFollowerState();
819 public void onFailure(ActorRef raftActorRef) {
820 LOG.debug("{}: leader transfer failed after change to non-voting", persistenceId());
821 ensureFollowerState();
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();
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.
840 // Suppressing this warning as we can't set serialVersionUID to maintain backwards compatibility.
841 @SuppressWarnings("serial")
843 static class DeleteEntries implements Serializable {
844 private final int fromIndex;
846 public DeleteEntries(int fromIndex) {
847 this.fromIndex = fromIndex;
850 public int getFromIndex() {
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.
859 // Suppressing this warning as we can't set serialVersionUID to maintain backwards compatibility.
860 @SuppressWarnings("serial")
862 static class UpdateElectionTerm implements Serializable {
863 private final long currentTerm;
864 private final String votedFor;
866 public UpdateElectionTerm(long currentTerm, String votedFor) {
867 this.currentTerm = currentTerm;
868 this.votedFor = votedFor;
871 public long getCurrentTerm() {
875 public String getVotedFor() {
881 * A point-in-time capture of {@link RaftActorBehavior} state critical for transitioning between behaviors.
883 private static abstract class BehaviorState implements Immutable {
884 @Nullable abstract RaftActorBehavior getBehavior();
885 @Nullable abstract String getLastValidLeaderId();
886 @Nullable abstract short getLeaderPayloadVersion();
890 * A {@link BehaviorState} corresponding to non-null {@link RaftActorBehavior} state.
892 private static final class SimpleBehaviorState extends BehaviorState {
893 private final RaftActorBehavior behavior;
894 private final String lastValidLeaderId;
895 private final short leaderPayloadVersion;
897 SimpleBehaviorState(final String lastValidLeaderId, final RaftActorBehavior behavior) {
898 this.lastValidLeaderId = lastValidLeaderId;
899 this.behavior = Preconditions.checkNotNull(behavior);
900 this.leaderPayloadVersion = behavior.getLeaderPayloadVersion();
904 RaftActorBehavior getBehavior() {
909 String getLastValidLeaderId() {
910 return lastValidLeaderId;
914 short getLeaderPayloadVersion() {
915 return leaderPayloadVersion;
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
925 private static final class BehaviorStateTracker {
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.
930 private static final BehaviorState NULL_BEHAVIOR_STATE = new BehaviorState() {
932 RaftActorBehavior getBehavior() {
937 String getLastValidLeaderId() {
942 short getLeaderPayloadVersion() {
947 private String lastValidLeaderId;
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;
955 final String leaderId = behavior.getLeaderId();
956 if (leaderId != null) {
957 lastValidLeaderId = leaderId;
960 return new SimpleBehaviorState(lastValidLeaderId, behavior);