package org.opendaylight.controller.cluster.raft;
-import akka.persistence.UntypedEventsourcedProcessor;
-import org.opendaylight.controller.cluster.raft.behaviors.Candidate;
+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 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 java.util.Map;
+import java.util.concurrent.TimeUnit;
+import org.opendaylight.controller.cluster.DataPersistenceProvider;
+import org.opendaylight.controller.cluster.common.actor.AbstractUntypedPersistentActor;
+import org.opendaylight.controller.cluster.notifications.RoleChanged;
+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.Replicate;
+import org.opendaylight.controller.cluster.raft.base.messages.SendInstallSnapshot;
+import org.opendaylight.controller.cluster.raft.behaviors.AbstractRaftActorBehavior;
import org.opendaylight.controller.cluster.raft.behaviors.Follower;
-import org.opendaylight.controller.cluster.raft.behaviors.Leader;
import org.opendaylight.controller.cluster.raft.behaviors.RaftActorBehavior;
-
-import java.util.Collections;
+import org.opendaylight.controller.cluster.raft.client.messages.FindLeader;
+import org.opendaylight.controller.cluster.raft.client.messages.FindLeaderReply;
+import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
/**
* 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>
+ * In Search of an Understandable Consensus Algorithm</a>
+ * <p/>
* RaftActor has 3 states and each state has a certain behavior associated
* with it. A Raft actor can behave as,
* <ul>
- * <li> A Leader </li>
- * <li> A Follower (or) </li>
- * <li> A Candidate </li>
+ * <li> A Leader </li>
+ * <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>
* <li> when a snapshot should be saved </li>
* </ul>
- *
- * <a href="http://doc.akka.io/api/akka/2.3.3/index.html#akka.persistence.UntypedEventsourcedProcessor">UntypeEventSourceProcessor</a>
*/
-public abstract class RaftActor extends UntypedEventsourcedProcessor {
+public abstract class RaftActor extends AbstractUntypedPersistentActor {
+
+ private static final long APPLY_STATE_DELAY_THRESHOLD_IN_NANOS = TimeUnit.MILLISECONDS.toNanos(50L); // 50 millis
+
+ protected final Logger LOG = LoggerFactory.getLogger(getClass());
/**
- * The current state determines the current behavior of a RaftActor
+ * 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
*/
- private RaftActorContext context;
+ private final RaftActorContext context;
+
+ /**
+ * The in-memory journal
+ */
+ private ReplicatedLogImpl replicatedLog = new ReplicatedLogImpl();
+
+ private CaptureSnapshot captureSnapshot = null;
+
+ private Stopwatch recoveryTimer;
+
+ private int currentRecoveryBatchCount;
+
+ public RaftActor(String id, Map<String, String> peerAddresses) {
+ this(id, peerAddresses, Optional.<ConfigParams>absent());
+ }
+
+ public RaftActor(String id, Map<String, String> peerAddresses,
+ Optional<ConfigParams> configParams) {
- public RaftActor(String id){
context = new RaftActorContextImpl(this.getSelf(),
- this.getContext(),
- id, new ElectionTermImpl(id),
- 0, 0, new ReplicatedLogImpl());
- currentBehavior = switchBehavior(RaftState.Follower);
+ this.getContext(), id, new ElectionTermImpl(),
+ -1, -1, replicatedLog, peerAddresses,
+ (configParams.isPresent() ? configParams.get(): new DefaultConfigParamsImpl()),
+ LOG);
+ }
+
+ private void initRecoveryTimer() {
+ if(recoveryTimer == null) {
+ recoveryTimer = Stopwatch.createStarted();
+ }
+ }
+
+ @Override
+ public void preStart() throws Exception {
+ LOG.info("Starting recovery for {} with journal batch size {}", persistenceId(),
+ context.getConfigParams().getJournalRecoveryLogBatchSize());
+
+ super.preStart();
+ }
+
+ @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) {
+ onRecoveredApplyLogEntries((ApplyLogEntries) message);
+ } 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());
+
+ // Delete all the akka snapshots as they will not be needed
+ deleteSnapshots(new SnapshotSelectionCriteria(scala.Long.MaxValue(), scala.Long.MaxValue()));
+
+ onRecoveryComplete();
+
+ initializeBehavior();
+ }
+ }
+ }
+
+ private void onRecoveredSnapshot(SnapshotOffer offer) {
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: SnapshotOffer called..", persistenceId());
+ }
+
+ initRecoveryTimer();
+
+ Snapshot snapshot = (Snapshot) offer.snapshot();
+
+ // 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);
+
+ context.setReplicatedLog(replicatedLog);
+ context.setLastApplied(snapshot.getLastAppliedIndex());
+ context.setCommitIndex(snapshot.getLastAppliedIndex());
+
+ Stopwatch timer = Stopwatch.createStarted();
+
+ // Apply the snapshot to the actors state
+ applyRecoverySnapshot(snapshot.getState());
+
+ timer.stop();
+ LOG.info("Recovery snapshot applied for {} in {}: snapshotIndex={}, snapshotTerm={}, journal-size=" +
+ replicatedLog.size(), persistenceId(), timer.toString(),
+ replicatedLog.getSnapshotIndex(), replicatedLog.getSnapshotTerm());
+ }
+
+ private void onRecoveredJournalLogEntry(ReplicatedLogEntry logEntry) {
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: Received ReplicatedLogEntry for recovery: {}", persistenceId(), logEntry.getIndex());
+ }
+
+ replicatedLog.append(logEntry);
+ }
+
+ private void onRecoveredApplyLogEntries(ApplyLogEntries ale) {
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: Received ApplyLogEntries for recovery, applying to state: {} to {}",
+ persistenceId(), context.getLastApplied() + 1, ale.getToIndex());
+ }
+
+ for (long i = context.getLastApplied() + 1; i <= ale.getToIndex(); i++) {
+ batchRecoveredLogEntry(replicatedLog.get(i));
+ }
+
+ context.setLastApplied(ale.getToIndex());
+ context.setCommitIndex(ale.getToIndex());
+ }
+
+ private void batchRecoveredLogEntry(ReplicatedLogEntry logEntry) {
+ initRecoveryTimer();
+
+ int batchSize = context.getConfigParams().getJournalRecoveryLogBatchSize();
+ if(currentRecoveryBatchCount == 0) {
+ startLogRecoveryBatch(batchSize);
+ }
+
+ appendRecoveredLogEntry(logEntry.getData());
+
+ if(++currentRecoveryBatchCount >= batchSize) {
+ endCurrentLogRecoveryBatch();
+ }
+ }
+
+ private void endCurrentLogRecoveryBatch() {
+ applyCurrentLogRecoveryBatch();
+ currentRecoveryBatchCount = 0;
+ }
+
+ private void onRecoveryCompletedMessage() {
+ if(currentRecoveryBatchCount > 0) {
+ endCurrentLogRecoveryBatch();
+ }
+
+ onRecoveryComplete();
+
+ String recoveryTime = "";
+ if(recoveryTimer != null) {
+ recoveryTimer.stop();
+ recoveryTime = " in " + recoveryTimer.toString();
+ recoveryTimer = null;
+ }
+
+ 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());
+
+ initializeBehavior();
+ }
+
+ protected void initializeBehavior(){
+ changeCurrentBehavior(new Follower(context));
+ }
+
+ protected void changeCurrentBehavior(RaftActorBehavior newBehavior){
+ RaftActorBehavior oldBehavior = currentBehavior;
+ currentBehavior = newBehavior;
+ handleBehaviorChange(oldBehavior, currentBehavior);
+ }
+
+ @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);
+ }
+
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: Applying state for log index {} data {}",
+ persistenceId(), applyState.getReplicatedLogEntry().getIndex(),
+ applyState.getReplicatedLogEntry().getData());
+ }
+
+ applyState(applyState.getClientActor(), applyState.getIdentifier(),
+ applyState.getReplicatedLogEntry().getData());
+
+ } else if (message instanceof ApplyLogEntries){
+ ApplyLogEntries ale = (ApplyLogEntries) message;
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: Persisting ApplyLogEntries with index={}", persistenceId(), ale.getToIndex());
+ }
+ persistence().persist(new ApplyLogEntries(ale.getToIndex()), new Procedure<ApplyLogEntries>() {
+ @Override
+ public void apply(ApplyLogEntries param) throws Exception {
+ }
+ });
+
+ } else if(message instanceof ApplySnapshot ) {
+ Snapshot snapshot = ((ApplySnapshot) message).getSnapshot();
+
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: ApplySnapshot called on Follower Actor " +
+ "snapshotIndex:{}, snapshotTerm:{}", persistenceId(), snapshot.getLastAppliedIndex(),
+ snapshot.getLastAppliedTerm()
+ );
+ }
+
+ applySnapshot(snapshot.getState());
+
+ //clears the followers log, sets the snapshot index to ensure adjusted-index works
+ replicatedLog = new ReplicatedLogImpl(snapshot);
+ context.setReplicatedLog(replicatedLog);
+ context.setLastApplied(snapshot.getLastAppliedIndex());
+
+ } 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());
+
+ long sequenceNumber = success.metadata().sequenceNr();
+
+ commitSnapshot(sequenceNumber);
+
+ } else if (message instanceof SaveSnapshotFailure) {
+ SaveSnapshotFailure saveSnapshotFailure = (SaveSnapshotFailure) message;
+
+ LOG.error("{}: SaveSnapshotFailure received for snapshot Cause:",
+ persistenceId(), saveSnapshotFailure.cause());
+
+ context.getReplicatedLog().snapshotRollback();
+
+ 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());
+
+ } else if (message instanceof CaptureSnapshot) {
+ LOG.info("{}: CaptureSnapshot received by actor", persistenceId());
+
+ if(captureSnapshot == null) {
+ captureSnapshot = (CaptureSnapshot)message;
+ createSnapshot();
+ }
+
+ } else if (message instanceof CaptureSnapshotReply){
+ handleCaptureSnapshotReply(((CaptureSnapshotReply) message).getSnapshot());
+
+ } else {
+ RaftActorBehavior oldBehavior = currentBehavior;
+ currentBehavior = currentBehavior.handleMessage(getSender(), message);
+
+ handleBehaviorChange(oldBehavior, currentBehavior);
+ }
+ }
+
+ private void handleBehaviorChange(RaftActorBehavior oldBehavior, RaftActorBehavior currentBehavior) {
+ if (oldBehavior != currentBehavior){
+ onStateChanged();
+ }
+
+ String oldBehaviorLeaderId = oldBehavior == null? null : oldBehavior.getLeaderId();
+ String oldBehaviorState = oldBehavior == null? null : oldBehavior.state().name();
+
+ // it can happen that the state has not changed but the leader has changed.
+ onLeaderChanged(oldBehaviorLeaderId, currentBehavior.getLeaderId());
+
+ if (getRoleChangeNotifier().isPresent() &&
+ (oldBehavior == null || (oldBehavior.state() != currentBehavior.state()))) {
+ getRoleChangeNotifier().get().tell(
+ new RoleChanged(getId(), oldBehaviorState , currentBehavior.state().name()),
+ getSelf());
+ }
+ }
+
+ /**
+ * When a derived RaftActor needs to persist something it must call
+ * persistData.
+ *
+ * @param clientActor
+ * @param identifier
+ * @param data
+ */
+ protected void persistData(final ActorRef clientActor, final String identifier,
+ final Payload data) {
+
+ ReplicatedLogEntry replicatedLogEntry = new ReplicatedLogImplEntry(
+ context.getReplicatedLog().lastIndex() + 1,
+ context.getTermInformation().getCurrentTerm(), data);
+
+ if(LOG.isDebugEnabled()) {
+ 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 ApplyLogEntries message so that we write the fact that we applied
+ // the state to durable storage
+ self().tell(new ApplyLogEntries((int) 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)
+ );
+ }
+
+ }
+ }); }
+
+ protected String getId() {
+ return context.getId();
+ }
+
+ /**
+ * Derived actors can call the isLeader method to check if the current
+ * 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());
+ }
+
+ /**
+ * Derived actor can call getLeader if they need a reference to the Leader.
+ * This would be useful for example in forwarding a request to an actor
+ * which is the leader
+ *
+ * @return A reference to the leader if known, null otherwise
+ */
+ protected ActorSelection getLeader(){
+ String leaderAddress = getLeaderAddress();
+
+ if(leaderAddress == null){
+ return null;
+ }
+
+ return context.actorSelection(leaderAddress);
+ }
+
+ /**
+ *
+ * @return the current leader's id
+ */
+ protected String getLeaderId(){
+ return currentBehavior.getLeaderId();
}
- @Override public void onReceiveRecover(Object message) {
- throw new UnsupportedOperationException("onReceiveRecover");
+ protected RaftState getRaftState() {
+ return currentBehavior.state();
}
- @Override public void onReceiveCommand(Object message) {
- RaftState state = currentBehavior.handleMessage(getSender(), message);
- currentBehavior = switchBehavior(state);
+ protected ReplicatedLogEntry getLastLogEntry() {
+ return replicatedLog.last();
}
- private RaftActorBehavior switchBehavior(RaftState state){
- RaftActorBehavior behavior = null;
- if(state == RaftState.Candidate){
- behavior = new Candidate(context, Collections.EMPTY_LIST);
- } else if(state == RaftState.Follower){
- behavior = new Follower(context);
+ protected Long getCurrentTerm(){
+ return context.getTermInformation().getCurrentTerm();
+ }
+
+ protected Long getCommitIndex(){
+ return context.getCommitIndex();
+ }
+
+ protected Long getLastApplied(){
+ return context.getLastApplied();
+ }
+
+ protected RaftActorContext getRaftActorContext() {
+ return context;
+ }
+
+ /**
+ * 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){
+ 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
+ *
+ * @param clientActor A reference to the client who sent this message. This
+ * is the same reference that was passed to persistData
+ * by the derived actor. clientActor may be null when
+ * the RaftActor is behaving as a follower or during
+ * recovery.
+ * @param identifier The identifier of the persisted data. This is also
+ * the same identifier that was passed to persistData by
+ * the derived actor. identifier may be null when
+ * the RaftActor is behaving as a follower or during
+ * recovery
+ * @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);
+
+ /**
+ * 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.
+ */
+ 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();
+
+ /**
+ * 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
+ */
+ 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);
+
+ /**
+ * This method will be called by the RaftActor when the state of the
+ * RaftActor changes. The derived actor can then use methods like
+ * isLeader or getLeader to do something useful
+ */
+ protected abstract void onStateChanged();
+
+ protected abstract DataPersistenceProvider persistence();
+
+ /**
+ * 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){};
+
+ 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));
+
+ // Trim akka journal
+ persistence().deleteMessages(sequenceNumber);
+ }
+
+ private String getLeaderAddress(){
+ if(isLeader()){
+ return getSelf().path().toString();
+ }
+ String leaderId = currentBehavior.getLeaderId();
+ if (leaderId == null) {
+ return null;
+ }
+ String peerAddress = context.getPeerAddress(leaderId);
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: getLeaderAddress leaderId = {} peerAddress = {}",
+ persistenceId(), leaderId, peerAddress);
+ }
+
+ return peerAddress;
+ }
+
+ private void handleCaptureSnapshotReply(byte[] snapshotBytes) {
+ LOG.info("{}: 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 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());
+
} else {
- behavior = new Leader(context, Collections.EMPTY_LIST);
+ // clear the log based on replicatedToAllIndex
+ context.getReplicatedLog().snapshotPreCommit(captureSnapshot.getReplicatedToAllIndex(),
+ captureSnapshot.getReplicatedToAllTerm());
+ }
+ getCurrentBehavior().setReplicatedToAllIndex(captureSnapshot.getReplicatedToAllIndex());
+
+ LOG.info("{}: Removed in-memory snapshotted entries, adjusted snaphsotIndex:{} " +
+ "and term:{}", persistenceId(), captureSnapshot.getLastAppliedIndex(),
+ captureSnapshot.getLastAppliedTerm());
+
+ 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)));
}
- return behavior;
+
+ captureSnapshot = null;
+ context.setSnapshotCaptureInitiated(false);
}
- private class ReplicatedLogImpl implements ReplicatedLog {
+ protected boolean hasFollowers(){
+ return getRaftActorContext().getPeerAddresses().keySet().size() > 0;
+ }
- @Override public ReplicatedLogEntry getReplicatedLogEntry(long index) {
- throw new UnsupportedOperationException("getReplicatedLogEntry");
+ private class ReplicatedLogImpl extends AbstractReplicatedLogImpl {
+
+ private static final int DATA_SIZE_DIVIDER = 5;
+ private long dataSizeSinceLastSnapshot = 0;
+
+ public ReplicatedLogImpl(Snapshot snapshot) {
+ super(snapshot.getLastAppliedIndex(), snapshot.getLastAppliedTerm(),
+ snapshot.getUnAppliedEntries());
+ }
+
+ 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>() {
+
+ @Override
+ public void apply(DeleteEntries param)
+ throws Exception {
+ //FIXME : Doing nothing for now
+ dataSize = 0;
+ for (ReplicatedLogEntry entry : journal) {
+ dataSize += entry.size();
+ }
+ }
+ });
+ }
+
+ @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);
+ }
+
+ // 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);
+ }
+ }
+ }
+ );
+ }
+
+ }
+
+ static class DeleteEntries implements Serializable {
+ private static final long serialVersionUID = 1L;
+ private final int fromIndex;
+
+ public DeleteEntries(int fromIndex) {
+ this.fromIndex = fromIndex;
}
- @Override public ReplicatedLogEntry last() {
- throw new UnsupportedOperationException("last");
+ public int getFromIndex() {
+ return fromIndex;
}
}
+
+
+ private class ElectionTermImpl implements ElectionTerm {
+ /**
+ * Identifier of the actor whose election term information this is
+ */
+ private long currentTerm = 0;
+ private String votedFor = null;
+
+ @Override
+ public long getCurrentTerm() {
+ return currentTerm;
+ }
+
+ @Override
+ public String getVotedFor() {
+ return votedFor;
+ }
+
+ @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
+ 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 {
+
+ }
+ });
+ }
+ }
+
+ static class UpdateElectionTerm implements Serializable {
+ private static final long serialVersionUID = 1L;
+ private final long currentTerm;
+ private final String votedFor;
+
+ public UpdateElectionTerm(long currentTerm, String votedFor) {
+ this.currentTerm = currentTerm;
+ this.votedFor = votedFor;
+ }
+
+ public long getCurrentTerm() {
+ return currentTerm;
+ }
+
+ public String getVotedFor() {
+ return votedFor;
+ }
+ }
+
+ protected class NonPersistentRaftDataProvider extends NonPersistentDataProvider {
+
+ public NonPersistentRaftDataProvider(){
+
+ }
+
+ /**
+ * 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);
+ }
+ }
+
+ @VisibleForTesting
+ void setCurrentBehavior(AbstractRaftActorBehavior behavior) {
+ currentBehavior = behavior;
+ }
+
+ protected RaftActorBehavior getCurrentBehavior() {
+ return currentBehavior;
+ }
+
}
Code Review / controller.git / blobdiff