/*
* Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
+ * Copyright (c) 2015 Brocade Communications Systems, Inc. and others. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 which accompanies this distribution,
import akka.actor.ActorRef;
import akka.actor.ActorSelection;
-import akka.japi.Procedure;
-import akka.persistence.RecoveryCompleted;
-import akka.persistence.SaveSnapshotFailure;
-import akka.persistence.SaveSnapshotSuccess;
-import akka.persistence.SnapshotOffer;
-import akka.persistence.SnapshotSelectionCriteria;
+import akka.actor.PoisonPill;
+import akka.actor.Status;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Optional;
-import com.google.common.base.Stopwatch;
-import com.google.protobuf.ByteString;
-import java.io.Serializable;
+import com.google.common.base.Preconditions;
+import com.google.common.base.Verify;
+import com.google.common.collect.Lists;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
import java.util.Map;
+import java.util.Objects;
import java.util.concurrent.TimeUnit;
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import org.apache.commons.lang3.time.DurationFormatUtils;
import org.opendaylight.controller.cluster.DataPersistenceProvider;
+import org.opendaylight.controller.cluster.DelegatingPersistentDataProvider;
+import org.opendaylight.controller.cluster.NonPersistentDataProvider;
+import org.opendaylight.controller.cluster.PersistentDataProvider;
import org.opendaylight.controller.cluster.common.actor.AbstractUntypedPersistentActor;
+import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
import org.opendaylight.controller.cluster.notifications.RoleChanged;
-import org.opendaylight.controller.cluster.raft.base.messages.ApplyJournalEntries;
-import org.opendaylight.controller.cluster.raft.base.messages.ApplyLogEntries;
-import org.opendaylight.controller.cluster.raft.base.messages.ApplySnapshot;
import org.opendaylight.controller.cluster.raft.base.messages.ApplyState;
-import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshot;
-import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshotReply;
+import org.opendaylight.controller.cluster.raft.base.messages.CheckConsensusReached;
+import org.opendaylight.controller.cluster.raft.base.messages.InitiateCaptureSnapshot;
+import org.opendaylight.controller.cluster.raft.base.messages.LeaderTransitioning;
import org.opendaylight.controller.cluster.raft.base.messages.Replicate;
-import org.opendaylight.controller.cluster.raft.base.messages.SendInstallSnapshot;
+import org.opendaylight.controller.cluster.raft.base.messages.SwitchBehavior;
+import org.opendaylight.controller.cluster.raft.behaviors.AbstractLeader;
import org.opendaylight.controller.cluster.raft.behaviors.AbstractRaftActorBehavior;
import org.opendaylight.controller.cluster.raft.behaviors.Follower;
import org.opendaylight.controller.cluster.raft.behaviors.RaftActorBehavior;
import org.opendaylight.controller.cluster.raft.client.messages.FindLeader;
import org.opendaylight.controller.cluster.raft.client.messages.FindLeaderReply;
+import org.opendaylight.controller.cluster.raft.client.messages.FollowerInfo;
+import org.opendaylight.controller.cluster.raft.client.messages.GetOnDemandRaftState;
+import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
+import org.opendaylight.controller.cluster.raft.client.messages.Shutdown;
+import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
+import org.opendaylight.controller.cluster.raft.persisted.ApplyJournalEntries;
+import org.opendaylight.controller.cluster.raft.persisted.NoopPayload;
+import org.opendaylight.controller.cluster.raft.persisted.ServerConfigurationPayload;
+import org.opendaylight.controller.cluster.raft.persisted.SimpleReplicatedLogEntry;
import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+import org.opendaylight.yangtools.concepts.Identifier;
+import org.opendaylight.yangtools.concepts.Immutable;
/**
* RaftActor encapsulates a state machine that needs to be kept synchronized
* in a cluster. It implements the RAFT algorithm as described in the paper
* <a href='https://ramcloud.stanford.edu/wiki/download/attachments/11370504/raft.pdf'>
* In Search of an Understandable Consensus Algorithm</a>
- * <p/>
+ *
+ * <p>
* RaftActor has 3 states and each state has a certain behavior associated
* with it. A Raft actor can behave as,
* <ul>
* <li> A Follower (or) </li>
* <li> A Candidate </li>
* </ul>
- * <p/>
- * <p/>
+ *
+ * <p>
* A RaftActor MUST be a Leader in order to accept requests from clients to
* change the state of it's encapsulated state machine. Once a RaftActor becomes
* a Leader it is also responsible for ensuring that all followers ultimately
* have the same log and therefore the same state machine as itself.
- * <p/>
- * <p/>
+ *
+ * <p>
* The current behavior of a RaftActor determines how election for leadership
* is initiated and how peer RaftActors react to request for votes.
- * <p/>
- * <p/>
+ *
+ * <p>
* Each RaftActor also needs to know the current election term. It uses this
* information for a couple of things. One is to simply figure out who it
* voted for in the last election. Another is to figure out if the message
* it received to update it's state is stale.
- * <p/>
- * <p/>
+ *
+ * <p>
* The RaftActor uses akka-persistence to store it's replicated log.
* Furthermore through it's behaviors a Raft Actor determines
- * <p/>
* <ul>
* <li> when a log entry should be persisted </li>
* <li> when a log entry should be applied to the state machine (and) </li>
private static final long APPLY_STATE_DELAY_THRESHOLD_IN_NANOS = TimeUnit.MILLISECONDS.toNanos(50L); // 50 millis
- private static final Procedure<ApplyJournalEntries> APPLY_JOURNAL_ENTRIES_PERSIST_CALLBACK =
- new Procedure<ApplyJournalEntries>() {
- @Override
- public void apply(ApplyJournalEntries param) throws Exception {
- }
- };
-
- protected final Logger LOG = LoggerFactory.getLogger(getClass());
-
- /**
- * The current state determines the current behavior of a RaftActor
- * A Raft Actor always starts off in the Follower State
- */
- private RaftActorBehavior currentBehavior;
-
/**
* This context should NOT be passed directly to any other actor it is
- * only to be consumed by the RaftActorBehaviors
+ * only to be consumed by the RaftActorBehaviors.
*/
private final RaftActorContextImpl context;
- /**
- * The in-memory journal
- */
- private ReplicatedLogImpl replicatedLog = new ReplicatedLogImpl();
+ private final DelegatingPersistentDataProvider delegatingPersistenceProvider;
- private CaptureSnapshot captureSnapshot = null;
+ private final PersistentDataProvider persistentProvider;
- private Stopwatch recoveryTimer;
+ private final BehaviorStateTracker behaviorStateTracker = new BehaviorStateTracker();
- private int currentRecoveryBatchCount;
+ private RaftActorRecoverySupport raftRecovery;
- public RaftActor(String id, Map<String, String> peerAddresses) {
- this(id, peerAddresses, Optional.<ConfigParams>absent());
- }
+ private RaftActorSnapshotMessageSupport snapshotSupport;
- public RaftActor(String id, Map<String, String> peerAddresses,
- Optional<ConfigParams> configParams) {
+ private RaftActorServerConfigurationSupport serverConfigurationSupport;
+
+ private boolean shuttingDown;
+
+ protected RaftActor(String id, Map<String, String> peerAddresses,
+ Optional<ConfigParams> configParams, short payloadVersion) {
+
+ persistentProvider = new PersistentDataProvider(this);
+ delegatingPersistenceProvider = new RaftActorDelegatingPersistentDataProvider(null, persistentProvider);
context = new RaftActorContextImpl(this.getSelf(),
- this.getContext(), id, new ElectionTermImpl(),
- -1, -1, replicatedLog, peerAddresses,
- (configParams.isPresent() ? configParams.get(): new DefaultConfigParamsImpl()),
- LOG);
- }
+ this.getContext(), id, new ElectionTermImpl(persistentProvider, id, LOG),
+ -1, -1, peerAddresses,
+ configParams.isPresent() ? configParams.get() : new DefaultConfigParamsImpl(),
+ delegatingPersistenceProvider, this::handleApplyState, LOG);
- private void initRecoveryTimer() {
- if(recoveryTimer == null) {
- recoveryTimer = Stopwatch.createStarted();
- }
+ context.setPayloadVersion(payloadVersion);
+ context.setReplicatedLog(ReplicatedLogImpl.newInstance(context));
}
@Override
context.getConfigParams().getJournalRecoveryLogBatchSize());
super.preStart();
+
+ snapshotSupport = newRaftActorSnapshotMessageSupport();
+ serverConfigurationSupport = new RaftActorServerConfigurationSupport(this);
}
@Override
public void postStop() {
- if(currentBehavior != null) {
- try {
- currentBehavior.close();
- } catch (Exception e) {
- LOG.debug("{}: Error closing behavior {}", persistenceId(), currentBehavior.state());
- }
- }
-
+ context.close();
super.postStop();
}
@Override
- public void handleRecover(Object message) {
- if(persistence().isRecoveryApplicable()) {
- if (message instanceof SnapshotOffer) {
- onRecoveredSnapshot((SnapshotOffer) message);
- } else if (message instanceof ReplicatedLogEntry) {
- onRecoveredJournalLogEntry((ReplicatedLogEntry) message);
- } else if (message instanceof ApplyLogEntries) {
- // Handle this message for backwards compatibility with pre-Lithium versions.
- onRecoveredApplyLogEntries(((ApplyLogEntries) message).getToIndex());
- } else if (message instanceof ApplyJournalEntries) {
- onRecoveredApplyLogEntries(((ApplyJournalEntries) message).getToIndex());
- } else if (message instanceof DeleteEntries) {
- replicatedLog.removeFrom(((DeleteEntries) message).getFromIndex());
- } else if (message instanceof UpdateElectionTerm) {
- context.getTermInformation().update(((UpdateElectionTerm) message).getCurrentTerm(),
- ((UpdateElectionTerm) message).getVotedFor());
- } else if (message instanceof RecoveryCompleted) {
- onRecoveryCompletedMessage();
- }
- } else {
- if (message instanceof RecoveryCompleted) {
- // Delete all the messages from the akka journal so that we do not end up with consistency issues
- // Note I am not using the dataPersistenceProvider and directly using the akka api here
- deleteMessages(lastSequenceNr());
+ protected void handleRecover(Object message) {
+ if (raftRecovery == null) {
+ raftRecovery = newRaftActorRecoverySupport();
+ }
- // Delete all the akka snapshots as they will not be needed
- deleteSnapshots(new SnapshotSelectionCriteria(scala.Long.MaxValue(), scala.Long.MaxValue()));
+ boolean recoveryComplete = raftRecovery.handleRecoveryMessage(message, persistentProvider);
+ if (recoveryComplete) {
+ onRecoveryComplete();
- onRecoveryComplete();
+ initializeBehavior();
- initializeBehavior();
- }
+ raftRecovery = null;
}
}
- private void onRecoveredSnapshot(SnapshotOffer offer) {
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: SnapshotOffer called..", persistenceId());
+ protected RaftActorRecoverySupport newRaftActorRecoverySupport() {
+ return new RaftActorRecoverySupport(context, getRaftActorRecoveryCohort());
+ }
+
+ @VisibleForTesting
+ void initializeBehavior() {
+ changeCurrentBehavior(new Follower(context));
+ }
+
+ @VisibleForTesting
+ @SuppressWarnings("checkstyle:IllegalCatch")
+ protected void changeCurrentBehavior(RaftActorBehavior newBehavior) {
+ final RaftActorBehavior currentBehavior = getCurrentBehavior();
+ if (currentBehavior != null) {
+ try {
+ currentBehavior.close();
+ } catch (Exception e) {
+ LOG.warn("{}: Error closing behavior {}", persistence(), currentBehavior, e);
+ }
}
- initRecoveryTimer();
+ final BehaviorState state = behaviorStateTracker.capture(currentBehavior);
+ setCurrentBehavior(newBehavior);
+ handleBehaviorChange(state, newBehavior);
+ }
- Snapshot snapshot = (Snapshot) offer.snapshot();
+ /**
+ * Method exposed for subclasses to plug-in their logic. This method is invoked by {@link #handleCommand(Object)}
+ * for messages which are not handled by this class. Subclasses overriding this class should fall back to this
+ * implementation for messages which they do not handle
+ *
+ * @param message Incoming command message
+ */
+ protected void handleNonRaftCommand(final Object message) {
+ unhandled(message);
+ }
- // Create a replicated log with the snapshot information
- // The replicated log can be used later on to retrieve this snapshot
- // when we need to install it on a peer
- replicatedLog = new ReplicatedLogImpl(snapshot);
+ /**
+ * Handles a message.
+ *
+ * @deprecated This method is not final for testing purposes. DO NOT OVERRIDE IT, override
+ * {@link #handleNonRaftCommand(Object)} instead.
+ */
+ @Deprecated
+ @Override
+ // FIXME: make this method final once our unit tests do not need to override it
+ protected void handleCommand(final Object message) {
+ if (serverConfigurationSupport.handleMessage(message, getSender())) {
+ return;
+ }
+ if (snapshotSupport.handleSnapshotMessage(message, getSender())) {
+ return;
+ }
+ if (message instanceof ApplyState) {
+ ApplyState applyState = (ApplyState) message;
- context.setReplicatedLog(replicatedLog);
- context.setLastApplied(snapshot.getLastAppliedIndex());
- context.setCommitIndex(snapshot.getLastAppliedIndex());
+ if (!hasFollowers()) {
+ // for single node, the capture should happen after the apply state
+ // as we delete messages from the persistent journal which have made it to the snapshot
+ // capturing the snapshot before applying makes the persistent journal and snapshot out of sync
+ // and recovery shows data missing
+ context.getReplicatedLog().captureSnapshotIfReady(applyState.getReplicatedLogEntry());
- Stopwatch timer = Stopwatch.createStarted();
+ context.getSnapshotManager().trimLog(context.getLastApplied());
+ }
- // Apply the snapshot to the actors state
- applyRecoverySnapshot(snapshot.getState());
+ possiblyHandleBehaviorMessage(message);
+ } else if (message instanceof ApplyJournalEntries) {
+ ApplyJournalEntries applyEntries = (ApplyJournalEntries) message;
+ LOG.debug("{}: Persisting ApplyJournalEntries with index={}", persistenceId(), applyEntries.getToIndex());
- timer.stop();
- LOG.info("Recovery snapshot applied for {} in {}: snapshotIndex={}, snapshotTerm={}, journal-size=" +
- replicatedLog.size(), persistenceId(), timer.toString(),
- replicatedLog.getSnapshotIndex(), replicatedLog.getSnapshotTerm());
- }
+ persistence().persistAsync(applyEntries, NoopProcedure.instance());
- private void onRecoveredJournalLogEntry(ReplicatedLogEntry logEntry) {
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: Received ReplicatedLogEntry for recovery: {}", persistenceId(), logEntry.getIndex());
+ } else if (message instanceof FindLeader) {
+ getSender().tell(
+ new FindLeaderReply(getLeaderAddress()),
+ getSelf()
+ );
+ } else if (message instanceof GetOnDemandRaftState) {
+ onGetOnDemandRaftStats();
+ } else if (message instanceof InitiateCaptureSnapshot) {
+ captureSnapshot();
+ } else if (message instanceof SwitchBehavior) {
+ switchBehavior((SwitchBehavior) message);
+ } else if (message instanceof LeaderTransitioning) {
+ onLeaderTransitioning((LeaderTransitioning)message);
+ } else if (message instanceof Shutdown) {
+ onShutDown();
+ } else if (message instanceof Runnable) {
+ ((Runnable)message).run();
+ } else if (message instanceof NoopPayload) {
+ persistData(null, null, (NoopPayload) message, false);
+ } else if (message instanceof RequestLeadership) {
+ onRequestLeadership((RequestLeadership) message);
+ } else if (!possiblyHandleBehaviorMessage(message)) {
+ handleNonRaftCommand(message);
}
-
- replicatedLog.append(logEntry);
}
- private void onRecoveredApplyLogEntries(long toIndex) {
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: Received ApplyLogEntries for recovery, applying to state: {} to {}",
- persistenceId(), context.getLastApplied() + 1, toIndex);
+ private void onRequestLeadership(final RequestLeadership message) {
+ LOG.debug("{}: onRequestLeadership {}", persistenceId(), message);
+ if (!isLeader()) {
+ // non-leader cannot satisfy leadership request
+ LOG.warn("{}: onRequestLeadership {} was sent to non-leader."
+ + " Current behavior: {}. Sending failure response",
+ persistenceId(), getCurrentBehavior().state());
+ message.getReplyTo().tell(new LeadershipTransferFailedException("Cannot transfer leader to "
+ + message.getRequestedFollowerId()
+ + ". RequestLeadership message was sent to non-leader " + persistenceId()), getSelf());
+ return;
}
- for (long i = context.getLastApplied() + 1; i <= toIndex; i++) {
- batchRecoveredLogEntry(replicatedLog.get(i));
+ final String requestedFollowerId = message.getRequestedFollowerId();
+ final ActorRef replyTo = message.getReplyTo();
+ initiateLeadershipTransfer(new RaftActorLeadershipTransferCohort.OnComplete() {
+ @Override
+ public void onSuccess(final ActorRef raftActorRef) {
+ // sanity check
+ if (!requestedFollowerId.equals(getLeaderId())) {
+ onFailure(raftActorRef);
+ }
+
+ LOG.debug("{}: Leadership transferred successfully to {}", persistenceId(), requestedFollowerId);
+ replyTo.tell(new Status.Success(null), getSelf());
+ }
+
+ @Override
+ public void onFailure(final ActorRef raftActorRef) {
+ LOG.debug("{}: LeadershipTransfer request from {} failed", persistenceId(), requestedFollowerId);
+ replyTo.tell(new Status.Failure(
+ new LeadershipTransferFailedException(
+ "Failed to transfer leadership to " + requestedFollowerId
+ + ". Follower is not ready to become leader")),
+ getSelf());
+ }
+ }, message.getRequestedFollowerId(), RaftActorLeadershipTransferCohort.USE_DEFAULT_LEADER_TIMEOUT);
+ }
+
+ private boolean possiblyHandleBehaviorMessage(final Object message) {
+ final RaftActorBehavior currentBehavior = getCurrentBehavior();
+ final BehaviorState state = behaviorStateTracker.capture(currentBehavior);
+
+ // A behavior indicates that it processed the change by returning a reference to the next behavior
+ // to be used. A null return indicates it has not processed the message and we should be passing it to
+ // the subclass for handling.
+ final RaftActorBehavior nextBehavior = currentBehavior.handleMessage(getSender(), message);
+ if (nextBehavior != null) {
+ switchBehavior(state, nextBehavior);
+ return true;
}
- context.setLastApplied(toIndex);
- context.setCommitIndex(toIndex);
+ return false;
}
- private void batchRecoveredLogEntry(ReplicatedLogEntry logEntry) {
- initRecoveryTimer();
+ private void initiateLeadershipTransfer(final RaftActorLeadershipTransferCohort.OnComplete onComplete,
+ @Nullable final String followerId, long newLeaderTimeoutInMillis) {
+ LOG.debug("{}: Initiating leader transfer", persistenceId());
- int batchSize = context.getConfigParams().getJournalRecoveryLogBatchSize();
- if(currentRecoveryBatchCount == 0) {
- startLogRecoveryBatch(batchSize);
- }
+ RaftActorLeadershipTransferCohort leadershipTransferInProgress = context.getRaftActorLeadershipTransferCohort();
+ if (leadershipTransferInProgress == null) {
+ leadershipTransferInProgress = new RaftActorLeadershipTransferCohort(this, followerId);
+ leadershipTransferInProgress.setNewLeaderTimeoutInMillis(newLeaderTimeoutInMillis);
+ leadershipTransferInProgress.addOnComplete(new RaftActorLeadershipTransferCohort.OnComplete() {
+ @Override
+ public void onSuccess(ActorRef raftActorRef) {
+ context.setRaftActorLeadershipTransferCohort(null);
+ }
+
+ @Override
+ public void onFailure(ActorRef raftActorRef) {
+ context.setRaftActorLeadershipTransferCohort(null);
+ }
+ });
- appendRecoveredLogEntry(logEntry.getData());
+ leadershipTransferInProgress.addOnComplete(onComplete);
- if(++currentRecoveryBatchCount >= batchSize) {
- endCurrentLogRecoveryBatch();
+ context.setRaftActorLeadershipTransferCohort(leadershipTransferInProgress);
+ leadershipTransferInProgress.init();
+
+ } else {
+ LOG.debug("{}: prior leader transfer in progress - adding callback", persistenceId());
+ leadershipTransferInProgress.addOnComplete(onComplete);
}
}
- private void endCurrentLogRecoveryBatch() {
- applyCurrentLogRecoveryBatch();
- currentRecoveryBatchCount = 0;
- }
+ private void onShutDown() {
+ LOG.debug("{}: onShutDown", persistenceId());
- private void onRecoveryCompletedMessage() {
- if(currentRecoveryBatchCount > 0) {
- endCurrentLogRecoveryBatch();
+ if (shuttingDown) {
+ return;
}
- onRecoveryComplete();
-
- String recoveryTime = "";
- if(recoveryTimer != null) {
- recoveryTimer.stop();
- recoveryTime = " in " + recoveryTimer.toString();
- recoveryTimer = null;
+ shuttingDown = true;
+
+ final RaftActorBehavior currentBehavior = context.getCurrentBehavior();
+ switch (currentBehavior.state()) {
+ case Leader:
+ case PreLeader:
+ // Fall-through to more work
+ break;
+ default:
+ // For non-leaders shutdown is a no-op
+ self().tell(PoisonPill.getInstance(), self());
+ return;
}
- LOG.info(
- "Recovery completed" + recoveryTime + " - Switching actor to Follower - " +
- "Persistence Id = " + persistenceId() +
- " Last index in log={}, snapshotIndex={}, snapshotTerm={}, " +
- "journal-size={}",
- replicatedLog.lastIndex(), replicatedLog.getSnapshotIndex(),
- replicatedLog.getSnapshotTerm(), replicatedLog.size());
+ if (context.hasFollowers()) {
+ initiateLeadershipTransfer(new RaftActorLeadershipTransferCohort.OnComplete() {
+ @Override
+ public void onSuccess(ActorRef raftActorRef) {
+ LOG.debug("{}: leader transfer succeeded - sending PoisonPill", persistenceId());
+ raftActorRef.tell(PoisonPill.getInstance(), raftActorRef);
+ }
- initializeBehavior();
- }
+ @Override
+ public void onFailure(ActorRef raftActorRef) {
+ LOG.debug("{}: leader transfer failed - sending PoisonPill", persistenceId());
+ raftActorRef.tell(PoisonPill.getInstance(), raftActorRef);
+ }
+ }, null, TimeUnit.MILLISECONDS.convert(2, TimeUnit.SECONDS));
+ } else {
+ pauseLeader(new TimedRunnable(context.getConfigParams().getElectionTimeOutInterval(), this) {
+ @Override
+ protected void doRun() {
+ self().tell(PoisonPill.getInstance(), self());
+ }
- protected void initializeBehavior(){
- changeCurrentBehavior(new Follower(context));
+ @Override
+ protected void doCancel() {
+ self().tell(PoisonPill.getInstance(), self());
+ }
+ });
+ }
}
- protected void changeCurrentBehavior(RaftActorBehavior newBehavior){
- RaftActorBehavior oldBehavior = currentBehavior;
- currentBehavior = newBehavior;
- handleBehaviorChange(oldBehavior, currentBehavior);
+ private void onLeaderTransitioning(final LeaderTransitioning leaderTransitioning) {
+ LOG.debug("{}: onLeaderTransitioning: {}", persistenceId(), leaderTransitioning);
+ Optional<ActorRef> roleChangeNotifier = getRoleChangeNotifier();
+ if (getRaftState() == RaftState.Follower && roleChangeNotifier.isPresent()
+ && leaderTransitioning.getLeaderId().equals(getCurrentBehavior().getLeaderId())) {
+ roleChangeNotifier.get().tell(newLeaderStateChanged(getId(), null,
+ getCurrentBehavior().getLeaderPayloadVersion()), getSelf());
+ }
}
- @Override public void handleCommand(Object message) {
- if (message instanceof ApplyState){
- ApplyState applyState = (ApplyState) message;
-
- long elapsedTime = (System.nanoTime() - applyState.getStartTime());
- if(elapsedTime >= APPLY_STATE_DELAY_THRESHOLD_IN_NANOS){
- LOG.warn("ApplyState took more time than expected. Elapsed Time = {} ms ApplyState = {}",
- TimeUnit.NANOSECONDS.toMillis(elapsedTime), applyState);
+ private void switchBehavior(SwitchBehavior message) {
+ if (!getRaftActorContext().getRaftPolicy().automaticElectionsEnabled()) {
+ RaftState newState = message.getNewState();
+ if (newState == RaftState.Leader || newState == RaftState.Follower) {
+ switchBehavior(behaviorStateTracker.capture(getCurrentBehavior()),
+ AbstractRaftActorBehavior.createBehavior(context, message.getNewState()));
+ getRaftActorContext().getTermInformation().updateAndPersist(message.getNewTerm(), "");
+ } else {
+ LOG.warn("Switching to behavior : {} - not supported", newState);
}
+ }
+ }
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: Applying state for log index {} data {}",
- persistenceId(), applyState.getReplicatedLogEntry().getIndex(),
- applyState.getReplicatedLogEntry().getData());
- }
+ private void switchBehavior(final BehaviorState oldBehaviorState, final RaftActorBehavior nextBehavior) {
+ setCurrentBehavior(nextBehavior);
+ handleBehaviorChange(oldBehaviorState, nextBehavior);
+ }
- applyState(applyState.getClientActor(), applyState.getIdentifier(),
- applyState.getReplicatedLogEntry().getData());
+ @VisibleForTesting
+ RaftActorSnapshotMessageSupport newRaftActorSnapshotMessageSupport() {
+ return new RaftActorSnapshotMessageSupport(context, getRaftActorSnapshotCohort());
+ }
- } else if (message instanceof ApplyJournalEntries){
- ApplyJournalEntries applyEntries = (ApplyJournalEntries) message;
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: Persisting ApplyLogEntries with index={}", persistenceId(), applyEntries.getToIndex());
- }
+ private void onGetOnDemandRaftStats() {
+ // Debugging message to retrieve raft stats.
- persistence().persist(applyEntries, APPLY_JOURNAL_ENTRIES_PERSIST_CALLBACK);
+ Map<String, String> peerAddresses = new HashMap<>();
+ Map<String, Boolean> peerVotingStates = new HashMap<>();
+ for (PeerInfo info: context.getPeers()) {
+ peerVotingStates.put(info.getId(), info.isVoting());
+ peerAddresses.put(info.getId(), info.getAddress() != null ? info.getAddress() : "");
+ }
- } else if(message instanceof ApplySnapshot ) {
- Snapshot snapshot = ((ApplySnapshot) message).getSnapshot();
+ final RaftActorBehavior currentBehavior = context.getCurrentBehavior();
+ OnDemandRaftState.AbstractBuilder<?> builder = newOnDemandRaftStateBuilder()
+ .commitIndex(context.getCommitIndex())
+ .currentTerm(context.getTermInformation().getCurrentTerm())
+ .inMemoryJournalDataSize(replicatedLog().dataSize())
+ .inMemoryJournalLogSize(replicatedLog().size())
+ .isSnapshotCaptureInitiated(context.getSnapshotManager().isCapturing())
+ .lastApplied(context.getLastApplied())
+ .lastIndex(replicatedLog().lastIndex())
+ .lastTerm(replicatedLog().lastTerm())
+ .leader(getLeaderId())
+ .raftState(currentBehavior.state().toString())
+ .replicatedToAllIndex(currentBehavior.getReplicatedToAllIndex())
+ .snapshotIndex(replicatedLog().getSnapshotIndex())
+ .snapshotTerm(replicatedLog().getSnapshotTerm())
+ .votedFor(context.getTermInformation().getVotedFor())
+ .isVoting(context.isVotingMember())
+ .peerAddresses(peerAddresses)
+ .peerVotingStates(peerVotingStates)
+ .customRaftPolicyClassName(context.getConfigParams().getCustomRaftPolicyImplementationClass());
+
+ ReplicatedLogEntry lastLogEntry = replicatedLog().last();
+ if (lastLogEntry != null) {
+ builder.lastLogIndex(lastLogEntry.getIndex());
+ builder.lastLogTerm(lastLogEntry.getTerm());
+ }
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: ApplySnapshot called on Follower Actor " +
- "snapshotIndex:{}, snapshotTerm:{}", persistenceId(), snapshot.getLastAppliedIndex(),
- snapshot.getLastAppliedTerm()
- );
+ if (getCurrentBehavior() instanceof AbstractLeader) {
+ AbstractLeader leader = (AbstractLeader)getCurrentBehavior();
+ Collection<String> followerIds = leader.getFollowerIds();
+ List<FollowerInfo> followerInfoList = Lists.newArrayListWithCapacity(followerIds.size());
+ for (String id: followerIds) {
+ final FollowerLogInformation info = leader.getFollower(id);
+ followerInfoList.add(new FollowerInfo(id, info.getNextIndex(), info.getMatchIndex(),
+ info.isFollowerActive(), DurationFormatUtils.formatDurationHMS(info.timeSinceLastActivity()),
+ context.getPeerInfo(info.getId()).isVoting()));
}
- applySnapshot(snapshot.getState());
+ builder.followerInfoList(followerInfoList);
+ }
- //clears the followers log, sets the snapshot index to ensure adjusted-index works
- replicatedLog = new ReplicatedLogImpl(snapshot);
- context.setReplicatedLog(replicatedLog);
- context.setLastApplied(snapshot.getLastAppliedIndex());
+ sender().tell(builder.build(), self());
- } else if (message instanceof FindLeader) {
- getSender().tell(
- new FindLeaderReply(getLeaderAddress()),
- getSelf()
- );
+ }
- } else if (message instanceof SaveSnapshotSuccess) {
- SaveSnapshotSuccess success = (SaveSnapshotSuccess) message;
- LOG.info("{}: SaveSnapshotSuccess received for snapshot", persistenceId());
+ protected OnDemandRaftState.AbstractBuilder<?> newOnDemandRaftStateBuilder() {
+ return OnDemandRaftState.builder();
+ }
- long sequenceNumber = success.metadata().sequenceNr();
+ private void handleBehaviorChange(BehaviorState oldBehaviorState, RaftActorBehavior currentBehavior) {
+ RaftActorBehavior oldBehavior = oldBehaviorState.getBehavior();
- commitSnapshot(sequenceNumber);
+ if (oldBehavior != currentBehavior) {
+ onStateChanged();
+ }
- } else if (message instanceof SaveSnapshotFailure) {
- SaveSnapshotFailure saveSnapshotFailure = (SaveSnapshotFailure) message;
+ String lastLeaderId = oldBehavior == null ? null : oldBehaviorState.getLastLeaderId();
+ String lastValidLeaderId = oldBehavior == null ? null : oldBehaviorState.getLastValidLeaderId();
+ String oldBehaviorStateName = oldBehavior == null ? null : oldBehavior.state().name();
- LOG.error("{}: SaveSnapshotFailure received for snapshot Cause:",
- persistenceId(), saveSnapshotFailure.cause());
+ // it can happen that the state has not changed but the leader has changed.
+ Optional<ActorRef> roleChangeNotifier = getRoleChangeNotifier();
+ if (!Objects.equals(lastLeaderId, currentBehavior.getLeaderId())
+ || oldBehaviorState.getLeaderPayloadVersion() != currentBehavior.getLeaderPayloadVersion()) {
+ if (roleChangeNotifier.isPresent()) {
+ roleChangeNotifier.get().tell(newLeaderStateChanged(getId(), currentBehavior.getLeaderId(),
+ currentBehavior.getLeaderPayloadVersion()), getSelf());
+ }
- context.getReplicatedLog().snapshotRollback();
+ onLeaderChanged(lastValidLeaderId, currentBehavior.getLeaderId());
- LOG.info("{}: Replicated Log rollbacked. Snapshot will be attempted in the next cycle." +
- "snapshotIndex:{}, snapshotTerm:{}, log-size:{}", persistenceId(),
- context.getReplicatedLog().getSnapshotIndex(),
- context.getReplicatedLog().getSnapshotTerm(),
- context.getReplicatedLog().size());
+ RaftActorLeadershipTransferCohort leadershipTransferInProgress =
+ context.getRaftActorLeadershipTransferCohort();
+ if (leadershipTransferInProgress != null) {
+ leadershipTransferInProgress.onNewLeader(currentBehavior.getLeaderId());
+ }
- } else if (message instanceof CaptureSnapshot) {
- LOG.debug("{}: CaptureSnapshot received by actor: {}", persistenceId(), message);
+ serverConfigurationSupport.onNewLeader(currentBehavior.getLeaderId());
+ }
- if(captureSnapshot == null) {
- captureSnapshot = (CaptureSnapshot)message;
- createSnapshot();
- }
+ if (roleChangeNotifier.isPresent()
+ && (oldBehavior == null || oldBehavior.state() != currentBehavior.state())) {
+ roleChangeNotifier.get().tell(new RoleChanged(getId(), oldBehaviorStateName ,
+ currentBehavior.state().name()), getSelf());
+ }
+ }
- } else if (message instanceof CaptureSnapshotReply){
- handleCaptureSnapshotReply(((CaptureSnapshotReply) message).getSnapshot());
+ private void handleApplyState(ApplyState applyState) {
+ long startTime = System.nanoTime();
- } else {
- RaftActorBehavior oldBehavior = currentBehavior;
- currentBehavior = currentBehavior.handleMessage(getSender(), message);
+ Payload payload = applyState.getReplicatedLogEntry().getData();
+ if (LOG.isDebugEnabled()) {
+ LOG.debug("{}: Applying state for log index {} data {}",
+ persistenceId(), applyState.getReplicatedLogEntry().getIndex(), payload);
+ }
- handleBehaviorChange(oldBehavior, currentBehavior);
+ if (!(payload instanceof NoopPayload) && !(payload instanceof ServerConfigurationPayload)) {
+ applyState(applyState.getClientActor(), applyState.getIdentifier(), payload);
}
- }
- private void handleBehaviorChange(RaftActorBehavior oldBehavior, RaftActorBehavior currentBehavior) {
- if (oldBehavior != currentBehavior){
- onStateChanged();
+ long elapsedTime = System.nanoTime() - startTime;
+ if (elapsedTime >= APPLY_STATE_DELAY_THRESHOLD_IN_NANOS) {
+ LOG.debug("ApplyState took more time than expected. Elapsed Time = {} ms ApplyState = {}",
+ TimeUnit.NANOSECONDS.toMillis(elapsedTime), applyState);
}
- String oldBehaviorLeaderId = oldBehavior == null? null : oldBehavior.getLeaderId();
- String oldBehaviorState = oldBehavior == null? null : oldBehavior.state().name();
+ // Send the ApplyState message back to self to handle further processing asynchronously.
+ self().tell(applyState, self());
+ }
- // it can happen that the state has not changed but the leader has changed.
- onLeaderChanged(oldBehaviorLeaderId, currentBehavior.getLeaderId());
+ protected LeaderStateChanged newLeaderStateChanged(String memberId, String leaderId, short leaderPayloadVersion) {
+ return new LeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
+ }
- if (getRoleChangeNotifier().isPresent() &&
- (oldBehavior == null || (oldBehavior.state() != currentBehavior.state()))) {
- getRoleChangeNotifier().get().tell(
- new RoleChanged(getId(), oldBehaviorState , currentBehavior.state().name()),
- getSelf());
- }
+ @Override
+ public long snapshotSequenceNr() {
+ // When we do a snapshot capture, we also capture and save the sequence-number of the persistent journal,
+ // so that we can delete the persistent journal based on the saved sequence-number
+ // However , when akka replays the journal during recovery, it replays it from the sequence number when the
+ // snapshot was saved and not the number we saved. We would want to override it , by asking akka to use the
+ // last-sequence number known to us.
+ return context.getSnapshotManager().getLastSequenceNumber();
}
/**
- * When a derived RaftActor needs to persist something it must call
- * persistData.
+ * Persists the given Payload in the journal and replicates to any followers. After successful completion,
+ * {@link #applyState(ActorRef, Identifier, Object)} is notified.
*
- * @param clientActor
- * @param identifier
- * @param data
+ * @param clientActor optional ActorRef that is provided via the applyState callback
+ * @param identifier the payload identifier
+ * @param data the payload data to persist
+ * @param batchHint if true, an attempt is made to delay immediate replication and batch the payload with
+ * subsequent payloads for efficiency. Otherwise the payload is immediately replicated.
*/
- protected void persistData(final ActorRef clientActor, final String identifier,
- final Payload data) {
-
- ReplicatedLogEntry replicatedLogEntry = new ReplicatedLogImplEntry(
+ protected final void persistData(final ActorRef clientActor, final Identifier identifier, final Payload data,
+ final boolean batchHint) {
+ ReplicatedLogEntry replicatedLogEntry = new SimpleReplicatedLogEntry(
context.getReplicatedLog().lastIndex() + 1,
context.getTermInformation().getCurrentTerm(), data);
+ replicatedLogEntry.setPersistencePending(true);
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: Persist data {}", persistenceId(), replicatedLogEntry);
- }
+ LOG.debug("{}: Persist data {}", persistenceId(), replicatedLogEntry);
final RaftActorContext raftContext = getRaftActorContext();
- replicatedLog
- .appendAndPersist(replicatedLogEntry, new Procedure<ReplicatedLogEntry>() {
- @Override
- public void apply(ReplicatedLogEntry replicatedLogEntry) throws Exception {
- if(!hasFollowers()){
- // Increment the Commit Index and the Last Applied values
- raftContext.setCommitIndex(replicatedLogEntry.getIndex());
- raftContext.setLastApplied(replicatedLogEntry.getIndex());
-
- // Apply the state immediately
- applyState(clientActor, identifier, data);
-
- // Send a ApplyJournalEntries message so that we write the fact that we applied
- // the state to durable storage
- self().tell(new ApplyJournalEntries(replicatedLogEntry.getIndex()), self());
-
- // Check if the "real" snapshot capture has been initiated. If no then do the fake snapshot
- if(!context.isSnapshotCaptureInitiated()){
- raftContext.getReplicatedLog().snapshotPreCommit(raftContext.getLastApplied(),
- raftContext.getTermInformation().getCurrentTerm());
- raftContext.getReplicatedLog().snapshotCommit();
- } else {
- LOG.debug("{}: Skipping fake snapshotting for {} because real snapshotting is in progress",
- persistenceId(), getId());
- }
- } else if (clientActor != null) {
- // Send message for replication
- currentBehavior.handleMessage(getSelf(),
- new Replicate(clientActor, identifier,
- replicatedLogEntry)
- );
- }
+ boolean wasAppended = replicatedLog().appendAndPersist(replicatedLogEntry, persistedLogEntry -> {
+ // Clear the persistence pending flag in the log entry.
+ persistedLogEntry.setPersistencePending(false);
- }
- }); }
+ if (!hasFollowers()) {
+ // Increment the Commit Index and the Last Applied values
+ raftContext.setCommitIndex(persistedLogEntry.getIndex());
+ raftContext.setLastApplied(persistedLogEntry.getIndex());
+
+ // Apply the state immediately.
+ handleApplyState(new ApplyState(clientActor, identifier, persistedLogEntry));
+
+ // Send a ApplyJournalEntries message so that we write the fact that we applied
+ // the state to durable storage
+ self().tell(new ApplyJournalEntries(persistedLogEntry.getIndex()), self());
+
+ } else {
+ context.getReplicatedLog().captureSnapshotIfReady(replicatedLogEntry);
+
+ // Local persistence is complete so send the CheckConsensusReached message to the behavior (which
+ // normally should still be the leader) to check if consensus has now been reached in conjunction with
+ // follower replication.
+ getCurrentBehavior().handleMessage(getSelf(), CheckConsensusReached.INSTANCE);
+ }
+ }, true);
+
+ if (wasAppended && hasFollowers()) {
+ // Send log entry for replication.
+ getCurrentBehavior().handleMessage(getSelf(), new Replicate(clientActor, identifier, replicatedLogEntry,
+ !batchHint));
+ }
+ }
+
+ private ReplicatedLog replicatedLog() {
+ return context.getReplicatedLog();
+ }
protected String getId() {
return context.getId();
}
+ @VisibleForTesting
+ void setCurrentBehavior(RaftActorBehavior behavior) {
+ context.setCurrentBehavior(behavior);
+ }
+
+ protected RaftActorBehavior getCurrentBehavior() {
+ return context.getCurrentBehavior();
+ }
+
/**
* Derived actors can call the isLeader method to check if the current
- * RaftActor is the Leader or not
+ * RaftActor is the Leader or not.
*
* @return true it this RaftActor is a Leader false otherwise
*/
protected boolean isLeader() {
- return context.getId().equals(currentBehavior.getLeaderId());
+ return context.getId().equals(getCurrentBehavior().getLeaderId());
+ }
+
+ protected final boolean isLeaderActive() {
+ return getRaftState() != RaftState.IsolatedLeader && getRaftState() != RaftState.PreLeader
+ && !shuttingDown && !isLeadershipTransferInProgress();
+ }
+
+ protected boolean isLeadershipTransferInProgress() {
+ RaftActorLeadershipTransferCohort leadershipTransferInProgress = context.getRaftActorLeadershipTransferCohort();
+ return leadershipTransferInProgress != null && leadershipTransferInProgress.isTransferring();
}
/**
*
* @return A reference to the leader if known, null otherwise
*/
- protected ActorSelection getLeader(){
+ public ActorSelection getLeader() {
String leaderAddress = getLeaderAddress();
- if(leaderAddress == null){
+ if (leaderAddress == null) {
return null;
}
}
/**
+ * Returns the id of the current leader.
*
* @return the current leader's id
*/
- protected String getLeaderId(){
- return currentBehavior.getLeaderId();
+ protected final String getLeaderId() {
+ return getCurrentBehavior().getLeaderId();
}
- protected RaftState getRaftState() {
- return currentBehavior.state();
+ @VisibleForTesting
+ protected final RaftState getRaftState() {
+ return getCurrentBehavior().state();
}
- protected ReplicatedLogEntry getLastLogEntry() {
- return replicatedLog.last();
+ protected Long getCurrentTerm() {
+ return context.getTermInformation().getCurrentTerm();
}
- protected Long getCurrentTerm(){
- return context.getTermInformation().getCurrentTerm();
+ protected RaftActorContext getRaftActorContext() {
+ return context;
}
- protected Long getCommitIndex(){
- return context.getCommitIndex();
+ protected void updateConfigParams(ConfigParams configParams) {
+
+ // obtain the RaftPolicy for oldConfigParams and the updated one.
+ String oldRaftPolicy = context.getConfigParams().getCustomRaftPolicyImplementationClass();
+ String newRaftPolicy = configParams.getCustomRaftPolicyImplementationClass();
+
+ LOG.debug("{}: RaftPolicy used with prev.config {}, RaftPolicy used with newConfig {}", persistenceId(),
+ oldRaftPolicy, newRaftPolicy);
+ context.setConfigParams(configParams);
+ if (!Objects.equals(oldRaftPolicy, newRaftPolicy)) {
+ // The RaftPolicy was modified. If the current behavior is Follower then re-initialize to Follower
+ // but transfer the previous leaderId so it doesn't immediately try to schedule an election. This
+ // avoids potential disruption. Otherwise, switch to Follower normally.
+ RaftActorBehavior behavior = getCurrentBehavior();
+ if (behavior != null && behavior.state() == RaftState.Follower) {
+ String previousLeaderId = behavior.getLeaderId();
+ short previousLeaderPayloadVersion = behavior.getLeaderPayloadVersion();
+
+ LOG.debug("{}: Re-initializing to Follower with previous leaderId {}", persistenceId(),
+ previousLeaderId);
+
+ changeCurrentBehavior(new Follower(context, previousLeaderId, previousLeaderPayloadVersion));
+ } else {
+ initializeBehavior();
+ }
+ }
}
- protected Long getLastApplied(){
- return context.getLastApplied();
+ public final DataPersistenceProvider persistence() {
+ return delegatingPersistenceProvider.getDelegate();
}
- protected RaftActorContext getRaftActorContext() {
- return context;
+ public void setPersistence(DataPersistenceProvider provider) {
+ delegatingPersistenceProvider.setDelegate(provider);
}
- protected void updateConfigParams(ConfigParams configParams) {
- context.setConfigParams(configParams);
+ protected void setPersistence(boolean persistent) {
+ DataPersistenceProvider currentPersistence = persistence();
+ if (persistent && (currentPersistence == null || !currentPersistence.isRecoveryApplicable())) {
+ setPersistence(new PersistentDataProvider(this));
+
+ if (getCurrentBehavior() != null) {
+ LOG.info("{}: Persistence has been enabled - capturing snapshot", persistenceId());
+ captureSnapshot();
+ }
+ } else if (!persistent && (currentPersistence == null || currentPersistence.isRecoveryApplicable())) {
+ setPersistence(new NonPersistentDataProvider() {
+ /**
+ * The way snapshotting works is,
+ * <ol>
+ * <li> RaftActor calls createSnapshot on the Shard
+ * <li> Shard sends a CaptureSnapshotReply and RaftActor then calls saveSnapshot
+ * <li> When saveSnapshot is invoked on the akka-persistence API it uses the SnapshotStore to save
+ * the snapshot. The SnapshotStore sends SaveSnapshotSuccess or SaveSnapshotFailure. When the
+ * RaftActor gets SaveSnapshot success it commits the snapshot to the in-memory journal. This
+ * commitSnapshot is mimicking what is done in SaveSnapshotSuccess.
+ * </ol>
+ */
+ @Override
+ public void saveSnapshot(Object object) {
+ // Make saving Snapshot successful
+ // Committing the snapshot here would end up calling commit in the creating state which would
+ // be a state violation. That's why now we send a message to commit the snapshot.
+ self().tell(RaftActorSnapshotMessageSupport.COMMIT_SNAPSHOT, self());
+ }
+ });
+ }
}
/**
* setPeerAddress sets the address of a known peer at a later time.
+ *
* <p>
* This is to account for situations where a we know that a peer
* exists but we do not know an address up-front. This may also be used in
* situations where a known peer starts off in a different location and we
* need to change it's address
+ *
* <p>
* Note that if the peerId does not match the list of peers passed to
* this actor during construction an IllegalStateException will be thrown.
- *
- * @param peerId
- * @param peerAddress
*/
- protected void setPeerAddress(String peerId, String peerAddress){
+ protected void setPeerAddress(String peerId, String peerAddress) {
context.setPeerAddress(peerId, peerAddress);
}
- protected void commitSnapshot(long sequenceNumber) {
- context.getReplicatedLog().snapshotCommit();
-
- // TODO: Not sure if we want to be this aggressive with trimming stuff
- trimPersistentData(sequenceNumber);
- }
-
/**
* The applyState method will be called by the RaftActor when some data
- * needs to be applied to the actor's state
+ * needs to be applied to the actor's state.
*
* @param clientActor A reference to the client who sent this message. This
* is the same reference that was passed to persistData
* @param data A piece of data that was persisted by the persistData call.
* This should NEVER be null.
*/
- protected abstract void applyState(ActorRef clientActor, String identifier,
- Object data);
+ protected abstract void applyState(ActorRef clientActor, Identifier identifier, Object data);
/**
- * This method is called during recovery at the start of a batch of state entries. Derived
- * classes should perform any initialization needed to start a batch.
+ * Returns the RaftActorRecoveryCohort to participate in persistence recovery.
*/
- protected abstract void startLogRecoveryBatch(int maxBatchSize);
-
- /**
- * This method is called during recovery to append state data to the current batch. This method
- * is called 1 or more times after {@link #startLogRecoveryBatch}.
- *
- * @param data the state data
- */
- protected abstract void appendRecoveredLogEntry(Payload data);
-
- /**
- * This method is called during recovery to reconstruct the state of the actor.
- *
- * @param snapshotBytes A snapshot of the state of the actor
- */
- protected abstract void applyRecoverySnapshot(byte[] snapshotBytes);
-
- /**
- * This method is called during recovery at the end of a batch to apply the current batched
- * log entries. This method is called after {@link #appendRecoveredLogEntry}.
- */
- protected abstract void applyCurrentLogRecoveryBatch();
+ @Nonnull
+ protected abstract RaftActorRecoveryCohort getRaftActorRecoveryCohort();
/**
* This method is called when recovery is complete.
protected abstract void onRecoveryComplete();
/**
- * This method will be called by the RaftActor when a snapshot needs to be
- * created. The derived actor should respond with its current state.
- * <p/>
- * During recovery the state that is returned by the derived actor will
- * be passed back to it by calling the applySnapshot method
- *
- * @return The current state of the actor
+ * Returns the RaftActorSnapshotCohort to participate in snapshot captures.
*/
- protected abstract void createSnapshot();
-
- /**
- * This method can be called at any other point during normal
- * operations when the derived actor is out of sync with it's peers
- * and the only way to bring it in sync is by applying a snapshot
- *
- * @param snapshotBytes A snapshot of the state of the actor
- */
- protected abstract void applySnapshot(byte[] snapshotBytes);
+ @Nonnull
+ protected abstract RaftActorSnapshotCohort getRaftActorSnapshotCohort();
/**
* This method will be called by the RaftActor when the state of the
*/
protected abstract void onStateChanged();
- protected abstract DataPersistenceProvider persistence();
-
/**
- * Notifier Actor for this RaftActor to notify when a role change happens
+ * Notifier Actor for this RaftActor to notify when a role change happens.
+ *
* @return ActorRef - ActorRef of the notifier or Optional.absent if none.
*/
protected abstract Optional<ActorRef> getRoleChangeNotifier();
- protected void onLeaderChanged(String oldLeader, String newLeader){};
+ /**
+ * This method is called prior to operations such as leadership transfer and actor shutdown when the leader
+ * must pause or stop its duties. This method allows derived classes to gracefully pause or finish current
+ * work prior to performing the operation. On completion of any work, the run method must be called on the
+ * given Runnable to proceed with the given operation. <b>Important:</b> the run method must be called on
+ * this actor's thread dispatcher as as it modifies internal state.
+ *
+ * <p>
+ * The default implementation immediately runs the operation.
+ *
+ * @param operation the operation to run
+ */
+ protected void pauseLeader(Runnable operation) {
+ operation.run();
+ }
- private void trimPersistentData(long sequenceNumber) {
- // Trim akka snapshots
- // FIXME : Not sure how exactly the SnapshotSelectionCriteria is applied
- // For now guessing that it is ANDed.
- persistence().deleteSnapshots(new SnapshotSelectionCriteria(
- sequenceNumber - context.getConfigParams().getSnapshotBatchCount(), 43200000));
+ /**
+ * This method is invoked when the actions hooked to the leader becoming paused failed to execute and the leader
+ * should resume normal operations.
+ *
+ * <p>
+ * Note this method can be invoked even before the operation supplied to {@link #pauseLeader(Runnable)} is invoked.
+ */
+ protected void unpauseLeader() {
+
+ }
- // Trim akka journal
- persistence().deleteMessages(sequenceNumber);
+ protected void onLeaderChanged(String oldLeader, String newLeader) {
}
- private String getLeaderAddress(){
- if(isLeader()){
+ private String getLeaderAddress() {
+ if (isLeader()) {
return getSelf().path().toString();
}
- String leaderId = currentBehavior.getLeaderId();
+ String leaderId = getLeaderId();
if (leaderId == null) {
return null;
}
String peerAddress = context.getPeerAddress(leaderId);
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: getLeaderAddress leaderId = {} peerAddress = {}",
- persistenceId(), leaderId, peerAddress);
- }
+ LOG.debug("{}: getLeaderAddress leaderId = {} peerAddress = {}", persistenceId(), leaderId, peerAddress);
return peerAddress;
}
- private void handleCaptureSnapshotReply(byte[] snapshotBytes) {
- LOG.debug("{}: CaptureSnapshotReply received by actor: snapshot size {}", persistenceId(), snapshotBytes.length);
-
- // create a snapshot object from the state provided and save it
- // when snapshot is saved async, SaveSnapshotSuccess is raised.
-
- Snapshot sn = Snapshot.create(snapshotBytes,
- context.getReplicatedLog().getFrom(captureSnapshot.getLastAppliedIndex() + 1),
- captureSnapshot.getLastIndex(), captureSnapshot.getLastTerm(),
- captureSnapshot.getLastAppliedIndex(), captureSnapshot.getLastAppliedTerm());
-
- persistence().saveSnapshot(sn);
-
- LOG.info("{}: Persisting of snapshot done:{}", persistenceId(), sn.getLogMessage());
-
- long dataThreshold = Runtime.getRuntime().totalMemory() *
- getRaftActorContext().getConfigParams().getSnapshotDataThresholdPercentage() / 100;
- if (context.getReplicatedLog().dataSize() > dataThreshold) {
-
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: dataSize {} exceeds dataThreshold {} - doing snapshotPreCommit with index {}",
- persistenceId(), context.getReplicatedLog().dataSize(), dataThreshold,
- captureSnapshot.getLastAppliedIndex());
- }
-
- // if memory is less, clear the log based on lastApplied.
- // this could/should only happen if one of the followers is down
- // as normally we keep removing from the log when its replicated to all.
- context.getReplicatedLog().snapshotPreCommit(captureSnapshot.getLastAppliedIndex(),
- captureSnapshot.getLastAppliedTerm());
-
- // Don't reset replicatedToAllIndex to -1 as this may prevent us from trimming the log after an
- // install snapshot to a follower.
- if(captureSnapshot.getReplicatedToAllIndex() >= 0) {
- getCurrentBehavior().setReplicatedToAllIndex(captureSnapshot.getReplicatedToAllIndex());
- }
- } else if(captureSnapshot.getReplicatedToAllIndex() != -1){
- // clear the log based on replicatedToAllIndex
- context.getReplicatedLog().snapshotPreCommit(captureSnapshot.getReplicatedToAllIndex(),
- captureSnapshot.getReplicatedToAllTerm());
-
- getCurrentBehavior().setReplicatedToAllIndex(captureSnapshot.getReplicatedToAllIndex());
- } else {
- // The replicatedToAllIndex was not found in the log
- // This means that replicatedToAllIndex never moved beyond -1 or that it is already in the snapshot.
- // In this scenario we may need to save the snapshot to the akka persistence
- // snapshot for recovery but we do not need to do the replicated log trimming.
- context.getReplicatedLog().snapshotPreCommit(replicatedLog.getSnapshotIndex(),
- replicatedLog.getSnapshotTerm());
- }
-
-
- LOG.info("{}: Removed in-memory snapshotted entries, adjusted snaphsotIndex: {} " +
- "and term: {}", persistenceId(), replicatedLog.getSnapshotIndex(),
- replicatedLog.getSnapshotTerm());
-
- if (isLeader() && captureSnapshot.isInstallSnapshotInitiated()) {
- // this would be call straight to the leader and won't initiate in serialization
- currentBehavior.handleMessage(getSelf(), new SendInstallSnapshot(
- ByteString.copyFrom(snapshotBytes)));
- }
-
- captureSnapshot = null;
- context.setSnapshotCaptureInitiated(false);
- }
-
- protected boolean hasFollowers(){
- return getRaftActorContext().getPeerAddresses().keySet().size() > 0;
+ protected boolean hasFollowers() {
+ return getRaftActorContext().hasFollowers();
}
- private class ReplicatedLogImpl extends AbstractReplicatedLogImpl {
+ private void captureSnapshot() {
+ SnapshotManager snapshotManager = context.getSnapshotManager();
- private static final int DATA_SIZE_DIVIDER = 5;
- private long dataSizeSinceLastSnapshot = 0;
+ if (!snapshotManager.isCapturing()) {
+ final long idx = getCurrentBehavior().getReplicatedToAllIndex();
+ LOG.debug("Take a snapshot of current state. lastReplicatedLog is {} and replicatedToAllIndex is {}",
+ replicatedLog().last(), idx);
- public ReplicatedLogImpl(Snapshot snapshot) {
- super(snapshot.getLastAppliedIndex(), snapshot.getLastAppliedTerm(),
- snapshot.getUnAppliedEntries());
+ snapshotManager.capture(replicatedLog().last(), idx);
}
+ }
- public ReplicatedLogImpl() {
- super();
- }
-
- @Override public void removeFromAndPersist(long logEntryIndex) {
- int adjustedIndex = adjustedIndex(logEntryIndex);
-
- if (adjustedIndex < 0) {
- return;
- }
-
- // FIXME: Maybe this should be done after the command is saved
- journal.subList(adjustedIndex , journal.size()).clear();
-
- persistence().persist(new DeleteEntries(adjustedIndex), new Procedure<DeleteEntries>() {
-
+ /**
+ * Switch this member to non-voting status. This is a no-op for all behaviors except when we are the leader,
+ * in which case we need to step down.
+ */
+ void becomeNonVoting() {
+ if (isLeader()) {
+ initiateLeadershipTransfer(new RaftActorLeadershipTransferCohort.OnComplete() {
@Override
- public void apply(DeleteEntries param)
- throws Exception {
- //FIXME : Doing nothing for now
- dataSize = 0;
- for (ReplicatedLogEntry entry : journal) {
- dataSize += entry.size();
- }
+ public void onSuccess(ActorRef raftActorRef) {
+ LOG.debug("{}: leader transfer succeeded after change to non-voting", persistenceId());
+ ensureFollowerState();
}
- });
- }
-
- @Override public void appendAndPersist(
- final ReplicatedLogEntry replicatedLogEntry) {
- appendAndPersist(replicatedLogEntry, null);
- }
-
- public void appendAndPersist(
- final ReplicatedLogEntry replicatedLogEntry,
- final Procedure<ReplicatedLogEntry> callback) {
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: Append log entry and persist {} ", persistenceId(), replicatedLogEntry);
- }
+ @Override
+ public void onFailure(ActorRef raftActorRef) {
+ LOG.debug("{}: leader transfer failed after change to non-voting", persistenceId());
+ ensureFollowerState();
+ }
- // FIXME : By adding the replicated log entry to the in-memory journal we are not truly ensuring durability of the logs
- journal.add(replicatedLogEntry);
-
- // When persisting events with persist it is guaranteed that the
- // persistent actor will not receive further commands between the
- // persist call and the execution(s) of the associated event
- // handler. This also holds for multiple persist calls in context
- // of a single command.
- persistence().persist(replicatedLogEntry,
- new Procedure<ReplicatedLogEntry>() {
- @Override
- public void apply(ReplicatedLogEntry evt) throws Exception {
- int logEntrySize = replicatedLogEntry.size();
-
- dataSize += logEntrySize;
- long dataSizeForCheck = dataSize;
-
- dataSizeSinceLastSnapshot += logEntrySize;
- long journalSize = lastIndex() + 1;
-
- if(!hasFollowers()) {
- // When we do not have followers we do not maintain an in-memory log
- // due to this the journalSize will never become anything close to the
- // snapshot batch count. In fact will mostly be 1.
- // Similarly since the journal's dataSize depends on the entries in the
- // journal the journal's dataSize will never reach a value close to the
- // memory threshold.
- // By maintaining the dataSize outside the journal we are tracking essentially
- // what we have written to the disk however since we no longer are in
- // need of doing a snapshot just for the sake of freeing up memory we adjust
- // the real size of data by the DATA_SIZE_DIVIDER so that we do not snapshot as often
- // as if we were maintaining a real snapshot
- dataSizeForCheck = dataSizeSinceLastSnapshot / DATA_SIZE_DIVIDER;
- }
-
- long dataThreshold = Runtime.getRuntime().totalMemory() *
- getRaftActorContext().getConfigParams().getSnapshotDataThresholdPercentage() / 100;
-
- // when a snaphsot is being taken, captureSnapshot != null
- if (!context.isSnapshotCaptureInitiated() &&
- ( journalSize % context.getConfigParams().getSnapshotBatchCount() == 0 ||
- dataSizeForCheck > dataThreshold)) {
-
- dataSizeSinceLastSnapshot = 0;
-
- LOG.info("{}: Initiating Snapshot Capture, journalSize = {}, dataSizeForCheck = {}," +
- " dataThreshold = {}", persistenceId(), journalSize, dataSizeForCheck, dataThreshold);
-
- long lastAppliedIndex = -1;
- long lastAppliedTerm = -1;
-
- ReplicatedLogEntry lastAppliedEntry = get(context.getLastApplied());
- if (!hasFollowers()) {
- lastAppliedIndex = replicatedLogEntry.getIndex();
- lastAppliedTerm = replicatedLogEntry.getTerm();
- } else if (lastAppliedEntry != null) {
- lastAppliedIndex = lastAppliedEntry.getIndex();
- lastAppliedTerm = lastAppliedEntry.getTerm();
- }
-
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: Snapshot Capture logSize: {}", persistenceId(), journal.size());
- LOG.debug("{}: Snapshot Capture lastApplied:{} ",
- persistenceId(), context.getLastApplied());
- LOG.debug("{}: Snapshot Capture lastAppliedIndex:{}", persistenceId(),
- lastAppliedIndex);
- LOG.debug("{}: Snapshot Capture lastAppliedTerm:{}", persistenceId(),
- lastAppliedTerm);
- }
-
- // send a CaptureSnapshot to self to make the expensive operation async.
- long replicatedToAllIndex = getCurrentBehavior().getReplicatedToAllIndex();
- ReplicatedLogEntry replicatedToAllEntry = context.getReplicatedLog().get(replicatedToAllIndex);
- getSelf().tell(new CaptureSnapshot(lastIndex(), lastTerm(), lastAppliedIndex, lastAppliedTerm,
- (replicatedToAllEntry != null ? replicatedToAllEntry.getIndex() : -1),
- (replicatedToAllEntry != null ? replicatedToAllEntry.getTerm() : -1)),
- null);
- context.setSnapshotCaptureInitiated(true);
- }
- if (callback != null){
- callback.apply(replicatedLogEntry);
- }
+ private void ensureFollowerState() {
+ // Whether or not leadership transfer succeeded, we have to step down as leader and
+ // switch to Follower so ensure that.
+ if (getRaftState() != RaftState.Follower) {
+ initializeBehavior();
}
}
- );
+ }, null, RaftActorLeadershipTransferCohort.USE_DEFAULT_LEADER_TIMEOUT);
}
-
}
- static class DeleteEntries implements Serializable {
- private static final long serialVersionUID = 1L;
- private final int fromIndex;
+ /**
+ * A point-in-time capture of {@link RaftActorBehavior} state critical for transitioning between behaviors.
+ */
+ private abstract static class BehaviorState implements Immutable {
+ @Nullable abstract RaftActorBehavior getBehavior();
- public DeleteEntries(int fromIndex) {
- this.fromIndex = fromIndex;
- }
+ @Nullable abstract String getLastValidLeaderId();
- public int getFromIndex() {
- return fromIndex;
- }
- }
+ @Nullable abstract String getLastLeaderId();
+ @Nullable abstract short getLeaderPayloadVersion();
+ }
- private class ElectionTermImpl implements ElectionTerm {
- /**
- * Identifier of the actor whose election term information this is
- */
- private long currentTerm = 0;
- private String votedFor = null;
+ /**
+ * A {@link BehaviorState} corresponding to non-null {@link RaftActorBehavior} state.
+ */
+ private static final class SimpleBehaviorState extends BehaviorState {
+ private final RaftActorBehavior behavior;
+ private final String lastValidLeaderId;
+ private final String lastLeaderId;
+ private final short leaderPayloadVersion;
+
+ SimpleBehaviorState(final String lastValidLeaderId, final String lastLeaderId,
+ final RaftActorBehavior behavior) {
+ this.lastValidLeaderId = lastValidLeaderId;
+ this.lastLeaderId = lastLeaderId;
+ this.behavior = Preconditions.checkNotNull(behavior);
+ this.leaderPayloadVersion = behavior.getLeaderPayloadVersion();
+ }
@Override
- public long getCurrentTerm() {
- return currentTerm;
+ RaftActorBehavior getBehavior() {
+ return behavior;
}
@Override
- public String getVotedFor() {
- return votedFor;
+ String getLastValidLeaderId() {
+ return lastValidLeaderId;
}
- @Override public void update(long currentTerm, String votedFor) {
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: Set currentTerm={}, votedFor={}", persistenceId(), currentTerm, votedFor);
- }
- this.currentTerm = currentTerm;
- this.votedFor = votedFor;
+ @Override
+ short getLeaderPayloadVersion() {
+ return leaderPayloadVersion;
}
@Override
- public void updateAndPersist(long currentTerm, String votedFor){
- update(currentTerm, votedFor);
- // FIXME : Maybe first persist then update the state
- persistence().persist(new UpdateElectionTerm(this.currentTerm, this.votedFor), new Procedure<UpdateElectionTerm>(){
-
- @Override public void apply(UpdateElectionTerm param)
- throws Exception {
-
- }
- });
+ String getLastLeaderId() {
+ return lastLeaderId;
}
}
- static class UpdateElectionTerm implements Serializable {
- private static final long serialVersionUID = 1L;
- private final long currentTerm;
- private final String votedFor;
+ /**
+ * Class tracking behavior-related information, which we need to keep around and pass across behavior switches.
+ * An instance is created for each RaftActor. It has two functions:
+ * - it keeps track of the last leader ID we have encountered since we have been created
+ * - it creates state capture needed to transition from one behavior to the next
+ */
+ private static final class BehaviorStateTracker {
+ /**
+ * A {@link BehaviorState} corresponding to null {@link RaftActorBehavior} state. Since null behavior is only
+ * allowed before we receive the first message, we know the leader ID to be null.
+ */
+ private static final BehaviorState NULL_BEHAVIOR_STATE = new BehaviorState() {
+ @Override
+ RaftActorBehavior getBehavior() {
+ return null;
+ }
- public UpdateElectionTerm(long currentTerm, String votedFor) {
- this.currentTerm = currentTerm;
- this.votedFor = votedFor;
- }
+ @Override
+ String getLastValidLeaderId() {
+ return null;
+ }
- public long getCurrentTerm() {
- return currentTerm;
- }
+ @Override
+ short getLeaderPayloadVersion() {
+ return -1;
+ }
- public String getVotedFor() {
- return votedFor;
- }
- }
+ @Override
+ String getLastLeaderId() {
+ return null;
+ }
+ };
- protected class NonPersistentRaftDataProvider extends NonPersistentDataProvider {
+ private String lastValidLeaderId;
+ private String lastLeaderId;
- public NonPersistentRaftDataProvider(){
+ BehaviorState capture(final RaftActorBehavior behavior) {
+ if (behavior == null) {
+ Verify.verify(lastValidLeaderId == null, "Null behavior with non-null last leader");
+ return NULL_BEHAVIOR_STATE;
+ }
- }
+ lastLeaderId = behavior.getLeaderId();
+ if (lastLeaderId != null) {
+ lastValidLeaderId = lastLeaderId;
+ }
- /**
- * The way snapshotting works is,
- * <ol>
- * <li> RaftActor calls createSnapshot on the Shard
- * <li> Shard sends a CaptureSnapshotReply and RaftActor then calls saveSnapshot
- * <li> When saveSnapshot is invoked on the akka-persistence API it uses the SnapshotStore to save the snapshot.
- * The SnapshotStore sends SaveSnapshotSuccess or SaveSnapshotFailure. When the RaftActor gets SaveSnapshot
- * success it commits the snapshot to the in-memory journal. This commitSnapshot is mimicking what is done
- * in SaveSnapshotSuccess.
- * </ol>
- * @param o
- */
- @Override
- public void saveSnapshot(Object o) {
- // Make saving Snapshot successful
- commitSnapshot(-1L);
+ return new SimpleBehaviorState(lastValidLeaderId, lastLeaderId, behavior);
}
}
- @VisibleForTesting
- void setCurrentBehavior(AbstractRaftActorBehavior behavior) {
- currentBehavior = behavior;
- }
-
- protected RaftActorBehavior getCurrentBehavior() {
- return currentBehavior;
- }
-
}
Code Review / controller.git / blobdiff