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/*
* Copyright (c) 2014 Cisco 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,
* and is available at http://www.eclipse.org/legal/epl-v10.html
*/
package org.opendaylight.controller.cluster.raft;
import akka.persistence.SnapshotSelectionCriteria;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.io.ByteSource;
import java.io.IOException;
import java.io.OutputStream;
import java.util.List;
import java.util.Optional;
import java.util.function.Consumer;
import org.eclipse.jdt.annotation.NonNull;
import org.opendaylight.controller.cluster.io.FileBackedOutputStream;
import org.opendaylight.controller.cluster.raft.base.messages.ApplySnapshot;
import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshot;
import org.opendaylight.controller.cluster.raft.base.messages.SendInstallSnapshot;
import org.opendaylight.controller.cluster.raft.base.messages.SnapshotComplete;
import org.opendaylight.controller.cluster.raft.behaviors.RaftActorBehavior;
import org.opendaylight.controller.cluster.raft.persisted.EmptyState;
import org.opendaylight.controller.cluster.raft.persisted.Snapshot;
import org.slf4j.Logger;
/**
* Manages the capturing of snapshots for a RaftActor.
*
* @author Moiz Raja
* @author Thomas Pantelis
*/
public class SnapshotManager implements SnapshotState {
@SuppressWarnings("checkstyle:MemberName")
private final SnapshotState IDLE = new Idle();
@SuppressWarnings({"checkstyle:MemberName", "checkstyle:AbbreviationAsWordInName"})
private final SnapshotState PERSISTING = new Persisting();
@SuppressWarnings({"checkstyle:MemberName", "checkstyle:AbbreviationAsWordInName"})
private final SnapshotState CREATING = new Creating();
private final Logger log;
private final RaftActorContext context;
private final LastAppliedTermInformationReader lastAppliedTermInformationReader =
new LastAppliedTermInformationReader();
private final ReplicatedToAllTermInformationReader replicatedToAllTermInformationReader =
new ReplicatedToAllTermInformationReader();
private SnapshotState currentState = IDLE;
private CaptureSnapshot captureSnapshot;
private long lastSequenceNumber = -1;
private Consumer> createSnapshotProcedure = null;
private ApplySnapshot applySnapshot;
private RaftActorSnapshotCohort snapshotCohort = NoopRaftActorSnapshotCohort.INSTANCE;
/**
* Constructs an instance.
*
* @param context the RaftActorContext
* @param logger the Logger
*/
public SnapshotManager(final RaftActorContext context, final Logger logger) {
this.context = context;
log = logger;
}
public boolean isApplying() {
return applySnapshot != null;
}
@Override
public boolean isCapturing() {
return currentState.isCapturing();
}
@Override
public boolean captureToInstall(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex,
final String targetFollower) {
return currentState.captureToInstall(lastLogEntry, replicatedToAllIndex, targetFollower);
}
@Override
public boolean capture(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex) {
return currentState.capture(lastLogEntry, replicatedToAllIndex);
}
@Override
public boolean captureWithForcedTrim(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex) {
return currentState.captureWithForcedTrim(lastLogEntry, replicatedToAllIndex);
}
@Override
public void apply(final ApplySnapshot snapshot) {
currentState.apply(snapshot);
}
@Override
public void persist(final Snapshot.State state, final Optional installSnapshotStream,
final long totalMemory) {
currentState.persist(state, installSnapshotStream, totalMemory);
}
@Override
public void commit(final long sequenceNumber, final long timeStamp) {
currentState.commit(sequenceNumber, timeStamp);
}
@Override
public void rollback() {
currentState.rollback();
}
@Override
public long trimLog(final long desiredTrimIndex) {
return currentState.trimLog(desiredTrimIndex);
}
@SuppressWarnings("checkstyle:hiddenField")
void setCreateSnapshotConsumer(final Consumer> createSnapshotProcedure) {
this.createSnapshotProcedure = createSnapshotProcedure;
}
void setSnapshotCohort(final RaftActorSnapshotCohort snapshotCohort) {
this.snapshotCohort = snapshotCohort;
}
public Snapshot.@NonNull State convertSnapshot(final ByteSource snapshotBytes) throws IOException {
return snapshotCohort.deserializeSnapshot(snapshotBytes);
}
public long getLastSequenceNumber() {
return lastSequenceNumber;
}
@VisibleForTesting
public CaptureSnapshot getCaptureSnapshot() {
return captureSnapshot;
}
private boolean hasFollowers() {
return context.hasFollowers();
}
private String persistenceId() {
return context.getId();
}
/**
* Constructs a CaptureSnapshot instance.
*
* @param lastLogEntry the last log entry for the snapshot.
* @param replicatedToAllIndex the index of the last entry replicated to all followers.
* @return a new CaptureSnapshot instance.
*/
public CaptureSnapshot newCaptureSnapshot(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex,
final boolean mandatoryTrim) {
TermInformationReader lastAppliedTermInfoReader =
lastAppliedTermInformationReader.init(context.getReplicatedLog(), context.getLastApplied(),
lastLogEntry, hasFollowers());
long lastAppliedIndex = lastAppliedTermInfoReader.getIndex();
long lastAppliedTerm = lastAppliedTermInfoReader.getTerm();
TermInformationReader replicatedToAllTermInfoReader =
replicatedToAllTermInformationReader.init(context.getReplicatedLog(), replicatedToAllIndex);
long newReplicatedToAllIndex = replicatedToAllTermInfoReader.getIndex();
long newReplicatedToAllTerm = replicatedToAllTermInfoReader.getTerm();
List unAppliedEntries = context.getReplicatedLog().getFrom(lastAppliedIndex + 1);
final long lastLogEntryIndex;
final long lastLogEntryTerm;
if (lastLogEntry == null) {
// When we don't have journal present, for example two captureSnapshots executed right after another with no
// new journal we still want to preserve the index and term in the snapshot.
lastAppliedIndex = lastLogEntryIndex = context.getReplicatedLog().getSnapshotIndex();
lastAppliedTerm = lastLogEntryTerm = context.getReplicatedLog().getSnapshotTerm();
log.debug("{}: Capturing Snapshot : lastLogEntry is null. Using snapshot values lastAppliedIndex {} and "
+ "lastAppliedTerm {} instead.", persistenceId(), lastAppliedIndex, lastAppliedTerm);
} else {
lastLogEntryIndex = lastLogEntry.getIndex();
lastLogEntryTerm = lastLogEntry.getTerm();
}
return new CaptureSnapshot(lastLogEntryIndex, lastLogEntryTerm, lastAppliedIndex, lastAppliedTerm,
newReplicatedToAllIndex, newReplicatedToAllTerm, unAppliedEntries, mandatoryTrim);
}
private abstract class AbstractSnapshotState implements SnapshotState {
@Override
public boolean isCapturing() {
return true;
}
@Override
public boolean capture(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex) {
log.debug("capture should not be called in state {}", this);
return false;
}
@Override
public boolean captureToInstall(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex,
final String targetFollower) {
log.debug("captureToInstall should not be called in state {}", this);
return false;
}
@Override
public boolean captureWithForcedTrim(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex) {
log.debug("captureWithForcedTrim should not be called in state {}", this);
return false;
}
@Override
public void apply(final ApplySnapshot snapshot) {
log.debug("apply should not be called in state {}", this);
}
@Override
public void persist(final Snapshot.State state, final Optional installSnapshotStream,
final long totalMemory) {
log.debug("persist should not be called in state {}", this);
}
@Override
public void commit(final long sequenceNumber, final long timeStamp) {
log.debug("commit should not be called in state {}", this);
}
@Override
public void rollback() {
log.debug("rollback should not be called in state {}", this);
}
@Override
public long trimLog(final long desiredTrimIndex) {
log.debug("trimLog should not be called in state {}", this);
return -1;
}
protected long doTrimLog(final long desiredTrimIndex) {
// we would want to keep the lastApplied as its used while capturing snapshots
long lastApplied = context.getLastApplied();
long tempMin = Math.min(desiredTrimIndex, lastApplied > -1 ? lastApplied - 1 : -1);
if (log.isTraceEnabled()) {
log.trace("{}: performSnapshotWithoutCapture: desiredTrimIndex: {}, lastApplied: {}, tempMin: {}",
persistenceId(), desiredTrimIndex, lastApplied, tempMin);
}
if (tempMin > -1 && context.getReplicatedLog().isPresent(tempMin)) {
log.debug("{}: fakeSnapshot purging log to {} for term {}", persistenceId(), tempMin,
context.getTermInformation().getCurrentTerm());
//use the term of the temp-min, since we check for isPresent, entry will not be null
ReplicatedLogEntry entry = context.getReplicatedLog().get(tempMin);
context.getReplicatedLog().snapshotPreCommit(tempMin, entry.getTerm());
context.getReplicatedLog().snapshotCommit(false);
return tempMin;
}
final RaftActorBehavior currentBehavior = context.getCurrentBehavior();
if (tempMin > currentBehavior.getReplicatedToAllIndex()) {
// It's possible a follower was lagging and an install snapshot advanced its match index past
// the current replicatedToAllIndex. Since the follower is now caught up we should advance the
// replicatedToAllIndex (to tempMin). The fact that tempMin wasn't found in the log is likely
// due to a previous snapshot triggered by the memory threshold exceeded, in that case we
// trim the log to the last applied index even if previous entries weren't replicated to all followers.
currentBehavior.setReplicatedToAllIndex(tempMin);
}
return -1;
}
}
private final class Idle extends AbstractSnapshotState {
@Override
public boolean isCapturing() {
return false;
}
@SuppressWarnings("checkstyle:IllegalCatch")
private boolean capture(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex,
final String targetFollower, final boolean mandatoryTrim) {
captureSnapshot = newCaptureSnapshot(lastLogEntry, replicatedToAllIndex, mandatoryTrim);
OutputStream installSnapshotStream = null;
if (targetFollower != null) {
installSnapshotStream = context.getFileBackedOutputStreamFactory().newInstance();
log.info("{}: Initiating snapshot capture {} to install on {}",
persistenceId(), captureSnapshot, targetFollower);
} else {
log.info("{}: Initiating snapshot capture {}", persistenceId(), captureSnapshot);
}
lastSequenceNumber = context.getPersistenceProvider().getLastSequenceNumber();
log.debug("{}: lastSequenceNumber prior to capture: {}", persistenceId(), lastSequenceNumber);
currentState = CREATING;
try {
createSnapshotProcedure.accept(Optional.ofNullable(installSnapshotStream));
} catch (Exception e) {
currentState = IDLE;
log.error("Error creating snapshot", e);
return false;
}
return true;
}
@Override
public boolean capture(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex) {
return capture(lastLogEntry, replicatedToAllIndex, null, false);
}
@Override
public boolean captureToInstall(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex,
final String targetFollower) {
return capture(lastLogEntry, replicatedToAllIndex, targetFollower, false);
}
@Override
public boolean captureWithForcedTrim(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex) {
return capture(lastLogEntry, replicatedToAllIndex, null, true);
}
@Override
public void apply(final ApplySnapshot toApply) {
applySnapshot = toApply;
lastSequenceNumber = context.getPersistenceProvider().getLastSequenceNumber();
log.debug("lastSequenceNumber prior to persisting applied snapshot: {}", lastSequenceNumber);
context.getPersistenceProvider().saveSnapshot(toApply.getSnapshot());
currentState = PERSISTING;
}
@Override
public String toString() {
return "Idle";
}
@Override
public long trimLog(final long desiredTrimIndex) {
return doTrimLog(desiredTrimIndex);
}
}
private final class Creating extends AbstractSnapshotState {
@Override
public void persist(final Snapshot.State snapshotState, final Optional installSnapshotStream,
final long totalMemory) {
// create a snapshot object from the state provided and save it
// when snapshot is saved async, SaveSnapshotSuccess is raised.
Snapshot snapshot = Snapshot.create(snapshotState,
captureSnapshot.getUnAppliedEntries(),
captureSnapshot.getLastIndex(), captureSnapshot.getLastTerm(),
captureSnapshot.getLastAppliedIndex(), captureSnapshot.getLastAppliedTerm(),
context.getTermInformation().getCurrentTerm(),
context.getTermInformation().getVotedFor(), context.getPeerServerInfo(true));
context.getPersistenceProvider().saveSnapshot(snapshot);
log.info("{}: Persisting of snapshot done: {}", persistenceId(), snapshot);
final ConfigParams config = context.getConfigParams();
final long absoluteThreshold = config.getSnapshotDataThreshold();
final long dataThreshold = absoluteThreshold != 0 ? absoluteThreshold * ConfigParams.MEGABYTE
: totalMemory * config.getSnapshotDataThresholdPercentage() / 100;
final boolean dataSizeThresholdExceeded = context.getReplicatedLog().dataSize() > dataThreshold;
final boolean logSizeExceededSnapshotBatchCount =
context.getReplicatedLog().size() >= config.getSnapshotBatchCount();
final RaftActorBehavior currentBehavior = context.getCurrentBehavior();
if (dataSizeThresholdExceeded || logSizeExceededSnapshotBatchCount || captureSnapshot.isMandatoryTrim()) {
if (log.isDebugEnabled()) {
if (dataSizeThresholdExceeded) {
log.debug("{}: log data size {} exceeds the memory threshold {} - doing snapshotPreCommit "
+ "with index {}", context.getId(), context.getReplicatedLog().dataSize(),
dataThreshold, captureSnapshot.getLastAppliedIndex());
} else if (logSizeExceededSnapshotBatchCount) {
log.debug("{}: log size {} exceeds the snapshot batch count {} - doing snapshotPreCommit with "
+ "index {}", context.getId(), context.getReplicatedLog().size(),
config.getSnapshotBatchCount(), captureSnapshot.getLastAppliedIndex());
} else {
log.debug("{}: user triggered or root overwrite snapshot encountered, trimming log up to "
+ "last applied index {}", context.getId(), captureSnapshot.getLastAppliedIndex());
}
}
// We either exceeded the memory threshold or the log size exceeded the snapshot batch
// count so, to keep the log memory footprint in check, 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 as entries are 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) {
currentBehavior.setReplicatedToAllIndex(captureSnapshot.getReplicatedToAllIndex());
}
} else if (captureSnapshot.getReplicatedToAllIndex() != -1) {
// clear the log based on replicatedToAllIndex
context.getReplicatedLog().snapshotPreCommit(captureSnapshot.getReplicatedToAllIndex(),
captureSnapshot.getReplicatedToAllTerm());
currentBehavior.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(context.getReplicatedLog().getSnapshotIndex(),
context.getReplicatedLog().getSnapshotTerm());
}
log.info("{}: Removed in-memory snapshotted entries, adjusted snaphsotIndex: {} and term: {}",
context.getId(), context.getReplicatedLog().getSnapshotIndex(),
context.getReplicatedLog().getSnapshotTerm());
if (installSnapshotStream.isPresent()) {
if (context.getId().equals(currentBehavior.getLeaderId())) {
try {
ByteSource snapshotBytes = ((FileBackedOutputStream)installSnapshotStream.orElseThrow())
.asByteSource();
currentBehavior.handleMessage(context.getActor(),
new SendInstallSnapshot(snapshot, snapshotBytes));
} catch (IOException e) {
log.error("{}: Snapshot install failed due to an unrecoverable streaming error",
context.getId(), e);
}
} else {
((FileBackedOutputStream)installSnapshotStream.orElseThrow()).cleanup();
}
}
captureSnapshot = null;
currentState = PERSISTING;
}
@Override
public String toString() {
return "Creating";
}
}
private final class Persisting extends AbstractSnapshotState {
@Override
@SuppressWarnings("checkstyle:IllegalCatch")
public void commit(final long sequenceNumber, final long timeStamp) {
log.debug("{}: Snapshot success - sequence number: {}", persistenceId(), sequenceNumber);
if (applySnapshot != null) {
try {
Snapshot snapshot = applySnapshot.getSnapshot();
//clears the followers log, sets the snapshot index to ensure adjusted-index works
context.setReplicatedLog(ReplicatedLogImpl.newInstance(snapshot, context));
context.setLastApplied(snapshot.getLastAppliedIndex());
context.setCommitIndex(snapshot.getLastAppliedIndex());
context.getTermInformation().update(snapshot.getElectionTerm(), snapshot.getElectionVotedFor());
if (snapshot.getServerConfiguration() != null) {
context.updatePeerIds(snapshot.getServerConfiguration());
}
if (!(snapshot.getState() instanceof EmptyState)) {
snapshotCohort.applySnapshot(snapshot.getState());
}
applySnapshot.getCallback().onSuccess();
} catch (Exception e) {
log.error("{}: Error applying snapshot", context.getId(), e);
}
} else {
context.getReplicatedLog().snapshotCommit();
}
context.getPersistenceProvider().deleteSnapshots(new SnapshotSelectionCriteria(scala.Long.MaxValue(),
timeStamp - 1, 0L, 0L));
context.getPersistenceProvider().deleteMessages(lastSequenceNumber);
snapshotComplete();
}
@Override
public void rollback() {
// Nothing to rollback if we're applying a snapshot from the leader.
if (applySnapshot == null) {
context.getReplicatedLog().snapshotRollback();
log.info("{}: Replicated Log rolled back. Snapshot will be attempted in the next cycle."
+ "snapshotIndex:{}, snapshotTerm:{}, log-size:{}", persistenceId(),
context.getReplicatedLog().getSnapshotIndex(),
context.getReplicatedLog().getSnapshotTerm(),
context.getReplicatedLog().size());
} else {
applySnapshot.getCallback().onFailure();
}
snapshotComplete();
}
private void snapshotComplete() {
lastSequenceNumber = -1;
applySnapshot = null;
currentState = IDLE;
context.getActor().tell(SnapshotComplete.INSTANCE, context.getActor());
}
@Override
public String toString() {
return "Persisting";
}
}
private interface TermInformationReader {
long getIndex();
long getTerm();
}
static final class LastAppliedTermInformationReader implements TermInformationReader {
private long index;
private long term;
LastAppliedTermInformationReader init(final ReplicatedLog log, final long originalIndex,
final ReplicatedLogEntry lastLogEntry, final boolean hasFollowers) {
ReplicatedLogEntry entry = log.get(originalIndex);
index = -1L;
term = -1L;
if (!hasFollowers) {
if (lastLogEntry != null) {
// since we have persisted the last-log-entry to persistent journal before the capture,
// we would want to snapshot from this entry.
index = lastLogEntry.getIndex();
term = lastLogEntry.getTerm();
}
} else if (entry != null) {
index = entry.getIndex();
term = entry.getTerm();
} else if (log.getSnapshotIndex() > -1) {
index = log.getSnapshotIndex();
term = log.getSnapshotTerm();
}
return this;
}
@Override
public long getIndex() {
return index;
}
@Override
public long getTerm() {
return term;
}
}
private static final class ReplicatedToAllTermInformationReader implements TermInformationReader {
private long index;
private long term;
ReplicatedToAllTermInformationReader init(final ReplicatedLog log, final long originalIndex) {
ReplicatedLogEntry entry = log.get(originalIndex);
index = -1L;
term = -1L;
if (entry != null) {
index = entry.getIndex();
term = entry.getTerm();
}
return this;
}
@Override
public long getIndex() {
return index;
}
@Override
public long getTerm() {
return term;
}
}
}
