import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
-import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableMap.Builder;
import com.google.protobuf.ByteString;
import java.io.IOException;
+import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
-import java.util.concurrent.TimeUnit;
+import java.util.Queue;
+import javax.annotation.Nullable;
import org.opendaylight.controller.cluster.raft.ClientRequestTracker;
import org.opendaylight.controller.cluster.raft.ClientRequestTrackerImpl;
import org.opendaylight.controller.cluster.raft.FollowerLogInformation;
import org.opendaylight.controller.cluster.raft.FollowerLogInformationImpl;
+import org.opendaylight.controller.cluster.raft.PeerInfo;
import org.opendaylight.controller.cluster.raft.RaftActorContext;
import org.opendaylight.controller.cluster.raft.RaftState;
import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry;
-import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshot;
-import org.opendaylight.controller.cluster.raft.base.messages.InitiateInstallSnapshot;
+import org.opendaylight.controller.cluster.raft.Snapshot;
+import org.opendaylight.controller.cluster.raft.VotingState;
import org.opendaylight.controller.cluster.raft.base.messages.Replicate;
import org.opendaylight.controller.cluster.raft.base.messages.SendHeartBeat;
import org.opendaylight.controller.cluster.raft.base.messages.SendInstallSnapshot;
import org.opendaylight.controller.cluster.raft.messages.InstallSnapshotReply;
import org.opendaylight.controller.cluster.raft.messages.RaftRPC;
import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply;
+import org.opendaylight.controller.cluster.raft.messages.UnInitializedFollowerSnapshotReply;
+import org.opendaylight.controller.cluster.raft.persisted.ServerConfigurationPayload;
import scala.concurrent.duration.FiniteDuration;
/**
// This would be passed as the hash code of the last chunk when sending the first chunk
public static final int INITIAL_LAST_CHUNK_HASH_CODE = -1;
- private final Map<String, FollowerLogInformation> followerToLog;
+ private final Map<String, FollowerLogInformation> followerToLog = new HashMap<>();
private final Map<String, FollowerToSnapshot> mapFollowerToSnapshot = new HashMap<>();
- private Cancellable heartbeatSchedule = null;
-
- private final Collection<ClientRequestTracker> trackerList = new LinkedList<>();
-
- protected final int minReplicationCount;
-
- protected final int minIsolatedLeaderPeerCount;
-
- private Optional<ByteString> snapshot;
-
- private long replicatedToAllIndex = -1;
-
- public AbstractLeader(RaftActorContext context) {
- super(context);
-
- final Builder<String, FollowerLogInformation> ftlBuilder = ImmutableMap.builder();
- for (String followerId : context.getPeerAddresses().keySet()) {
- FollowerLogInformation followerLogInformation =
- new FollowerLogInformationImpl(followerId,
- context.getCommitIndex(), -1,
- context.getConfigParams().getElectionTimeOutInterval());
+ /**
+ * Lookup table for request contexts based on journal index. We could use a {@link Map} here, but we really
+ * expect the entries to be modified in sequence, hence we open-code the lookup.
+ *
+ * TODO: Evaluate the use of ArrayDeque(), as that has lower memory overhead. Non-head removals are more costly,
+ * but we already expect those to be far from frequent.
+ */
+ private final Queue<ClientRequestTracker> trackers = new LinkedList<>();
- ftlBuilder.put(followerId, followerLogInformation);
+ private Cancellable heartbeatSchedule = null;
+ private Optional<SnapshotHolder> snapshot = Optional.absent();;
+ private int minReplicationCount;
+
+ protected AbstractLeader(RaftActorContext context, RaftState state,
+ @Nullable AbstractLeader initializeFromLeader) {
+ super(context, state);
+
+ if(initializeFromLeader != null) {
+ followerToLog.putAll(initializeFromLeader.followerToLog);
+ mapFollowerToSnapshot.putAll(initializeFromLeader.mapFollowerToSnapshot);
+ snapshot = initializeFromLeader.snapshot;
+ trackers.addAll(initializeFromLeader.trackers);
+ } else {
+ for(PeerInfo peerInfo: context.getPeers()) {
+ FollowerLogInformation followerLogInformation = new FollowerLogInformationImpl(peerInfo, -1, context);
+ followerToLog.put(peerInfo.getId(), followerLogInformation);
+ }
}
- followerToLog = ftlBuilder.build();
-
- leaderId = context.getId();
- LOG.debug("{}: Election: Leader has following peers: {}", context.getId(), getFollowerIds());
+ LOG.debug("{}: Election: Leader has following peers: {}", logName(), getFollowerIds());
- minReplicationCount = getMajorityVoteCount(getFollowerIds().size());
-
- // the isolated Leader peer count will be 1 less than the majority vote count.
- // this is because the vote count has the self vote counted in it
- // for e.g
- // 0 peers = 1 votesRequired , minIsolatedLeaderPeerCount = 0
- // 2 peers = 2 votesRequired , minIsolatedLeaderPeerCount = 1
- // 4 peers = 3 votesRequired, minIsolatedLeaderPeerCount = 2
- minIsolatedLeaderPeerCount = minReplicationCount > 0 ? (minReplicationCount - 1) : 0;
-
- snapshot = Optional.absent();
+ updateMinReplicaCount();
// Immediately schedule a heartbeat
// Upon election: send initial empty AppendEntries RPCs
// (heartbeat) to each server; repeat during idle periods to
// prevent election timeouts (§5.2)
- scheduleHeartBeat(new FiniteDuration(0, TimeUnit.SECONDS));
+ sendAppendEntries(0, false);
+
+ // It is important to schedule this heartbeat here
+ scheduleHeartBeat(context.getConfigParams().getHeartBeatInterval());
+ }
+
+ protected AbstractLeader(RaftActorContext context, RaftState state) {
+ this(context, state, null);
}
/**
*
* @return Collection of follower IDs
*/
- protected final Collection<String> getFollowerIds() {
+ public final Collection<String> getFollowerIds() {
return followerToLog.keySet();
}
- private Optional<ByteString> getSnapshot() {
- return snapshot;
+ public void addFollower(String followerId) {
+ FollowerLogInformation followerLogInformation = new FollowerLogInformationImpl(
+ context.getPeerInfo(followerId), -1, context);
+ followerToLog.put(followerId, followerLogInformation);
+
+ if(heartbeatSchedule == null) {
+ scheduleHeartBeat(context.getConfigParams().getHeartBeatInterval());
+ }
+ }
+
+ public void removeFollower(String followerId) {
+ followerToLog.remove(followerId);
+ mapFollowerToSnapshot.remove(followerId);
+ }
+
+ public void updateMinReplicaCount() {
+ int numVoting = 0;
+ for(PeerInfo peer: context.getPeers()) {
+ if(peer.isVoting()) {
+ numVoting++;
+ }
+ }
+
+ minReplicationCount = getMajorityVoteCount(numVoting);
+ }
+
+ protected int getMinIsolatedLeaderPeerCount(){
+ //the isolated Leader peer count will be 1 less than the majority vote count.
+ //this is because the vote count has the self vote counted in it
+ //for e.g
+ //0 peers = 1 votesRequired , minIsolatedLeaderPeerCount = 0
+ //2 peers = 2 votesRequired , minIsolatedLeaderPeerCount = 1
+ //4 peers = 3 votesRequired, minIsolatedLeaderPeerCount = 2
+
+ return minReplicationCount > 0 ? (minReplicationCount - 1) : 0;
}
@VisibleForTesting
- void setSnapshot(Optional<ByteString> snapshot) {
- this.snapshot = snapshot;
+ void setSnapshot(@Nullable Snapshot snapshot) {
+ if(snapshot != null) {
+ this.snapshot = Optional.of(new SnapshotHolder(snapshot));
+ } else {
+ this.snapshot = Optional.absent();
+ }
}
@Override
protected RaftActorBehavior handleAppendEntries(ActorRef sender,
AppendEntries appendEntries) {
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: handleAppendEntries: {}", context.getId(), appendEntries);
- }
+ LOG.debug("{}: handleAppendEntries: {}", logName(), appendEntries);
return this;
}
protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender,
AppendEntriesReply appendEntriesReply) {
- if(! appendEntriesReply.isSuccess()) {
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: handleAppendEntriesReply: {}", context.getId(), appendEntriesReply);
- }
+ if(LOG.isTraceEnabled()) {
+ LOG.trace("{}: handleAppendEntriesReply: {}", logName(), appendEntriesReply);
}
// Update the FollowerLogInformation
followerToLog.get(followerId);
if(followerLogInformation == null){
- LOG.error("{}: handleAppendEntriesReply - unknown follower {}", context.getId(), followerId);
+ LOG.error("{}: handleAppendEntriesReply - unknown follower {}", logName(), followerId);
return this;
}
- followerLogInformation.markFollowerActive();
+ if(followerLogInformation.timeSinceLastActivity() >
+ context.getConfigParams().getElectionTimeOutInterval().toMillis()) {
+ LOG.warn("{} : handleAppendEntriesReply delayed beyond election timeout, " +
+ "appendEntriesReply : {}, timeSinceLastActivity : {}, lastApplied : {}, commitIndex : {}",
+ logName(), appendEntriesReply, followerLogInformation.timeSinceLastActivity(),
+ context.getLastApplied(), context.getCommitIndex());
+ }
- if (appendEntriesReply.isSuccess()) {
- followerLogInformation
- .setMatchIndex(appendEntriesReply.getLogLastIndex());
- followerLogInformation
- .setNextIndex(appendEntriesReply.getLogLastIndex() + 1);
+ followerLogInformation.markFollowerActive();
+ followerLogInformation.setPayloadVersion(appendEntriesReply.getPayloadVersion());
+ followerLogInformation.setRaftVersion(appendEntriesReply.getRaftVersion());
+
+ boolean updated = false;
+ if(appendEntriesReply.getLogLastIndex() > context.getReplicatedLog().lastIndex()) {
+ // The follower's log is actually ahead of the leader's log. Normally this doesn't happen
+ // in raft as a node cannot become leader if it's log is behind another's. However, the
+ // non-voting semantics deviate a bit from raft. Only voting members participate in
+ // elections and can become leader so it's possible for a non-voting follower to be ahead
+ // of the leader. This can happen if persistence is disabled and all voting members are
+ // restarted. In this case, the voting leader will start out with an empty log however
+ // the non-voting followers still retain the previous data in memory. On the first
+ // AppendEntries, the non-voting follower returns a successful reply b/c the prevLogIndex
+ // sent by the leader is -1 and thus the integrity checks pass. However the follower's returned
+ // lastLogIndex may be higher in which case we want to reset the follower by installing a
+ // snapshot. It's also possible that the follower's last log index is behind the leader's.
+ // However in this case the log terms won't match and the logs will conflict - this is handled
+ // elsewhere.
+ LOG.debug("{}: handleAppendEntriesReply: follower {} lastIndex {} is ahead of our lastIndex {} - forcing install snaphot",
+ logName(), followerLogInformation.getId(), appendEntriesReply.getLogLastIndex(),
+ context.getReplicatedLog().lastIndex());
+
+ followerLogInformation.setMatchIndex(-1);
+ followerLogInformation.setNextIndex(-1);
+
+ initiateCaptureSnapshot(followerId);
+ updated = true;
+ } else if (appendEntriesReply.isSuccess()) {
+ updated = updateFollowerLogInformation(followerLogInformation, appendEntriesReply);
} else {
+ LOG.debug("{}: handleAppendEntriesReply: received unsuccessful reply: {}", logName(), appendEntriesReply);
+
+ long followerLastLogIndex = appendEntriesReply.getLogLastIndex();
+ long followersLastLogTerm = getLogEntryTerm(followerLastLogIndex);
+ if(appendEntriesReply.isForceInstallSnapshot()) {
+ // Reset the followers match and next index. This is to signal that this follower has nothing
+ // in common with this Leader and so would require a snapshot to be installed
+ followerLogInformation.setMatchIndex(-1);
+ followerLogInformation.setNextIndex(-1);
+
+ // Force initiate a snapshot capture
+ initiateCaptureSnapshot(followerId);
+ } else if(followerLastLogIndex < 0 || (followersLastLogTerm >= 0 &&
+ followersLastLogTerm == appendEntriesReply.getLogLastTerm())) {
+ // The follower's log is empty or the last entry is present in the leader's journal
+ // and the terms match so the follower is just behind the leader's journal from
+ // the last snapshot, if any. We'll catch up the follower quickly by starting at the
+ // follower's last log index.
+
+ updated = updateFollowerLogInformation(followerLogInformation, appendEntriesReply);
+ } else {
+ // The follower's log conflicts with leader's log so decrement follower's next index by 1
+ // in an attempt to find where the logs match.
- // TODO: When we find that the follower is out of sync with the
- // Leader we simply decrement that followers next index by 1.
- // Would it be possible to do better than this? The RAFT spec
- // does not explicitly deal with it but may be something for us to
- // think about
+ LOG.debug("{}: follower's last log term {} conflicts with the leader's {} - dec next index",
+ logName(), appendEntriesReply.getLogLastTerm(), followersLastLogTerm);
- followerLogInformation.decrNextIndex();
+ followerLogInformation.decrNextIndex();
+ }
}
// Now figure out if this reply warrants a change in the commitIndex
// If there exists an N such that N > commitIndex, a majority
// of matchIndex[i] ≥ N, and log[N].term == currentTerm:
// set commitIndex = N (§5.3, §5.4).
+ if(LOG.isTraceEnabled()) {
+ LOG.trace("{}: handleAppendEntriesReply from {}: commitIndex: {}, lastAppliedIndex: {}, currentTerm: {}",
+ logName(), followerId, context.getCommitIndex(), context.getLastApplied(), currentTerm());
+ }
+
for (long N = context.getCommitIndex() + 1; ; N++) {
int replicatedCount = 1;
+ LOG.trace("{}: checking Nth index {}", logName(), N);
for (FollowerLogInformation info : followerToLog.values()) {
- if (info.getMatchIndex() >= N) {
+ final PeerInfo peerInfo = context.getPeerInfo(info.getId());
+ if(info.getMatchIndex() >= N && peerInfo != null && peerInfo.isVoting()) {
replicatedCount++;
+ } else if(LOG.isTraceEnabled()) {
+ LOG.trace("{}: Not counting follower {} - matchIndex: {}, {}", logName(), info.getId(),
+ info.getMatchIndex(), peerInfo);
}
}
+ if(LOG.isTraceEnabled()) {
+ LOG.trace("{}: replicatedCount {}, minReplicationCount: {}", logName(), replicatedCount, minReplicationCount);
+ }
+
if (replicatedCount >= minReplicationCount) {
ReplicatedLogEntry replicatedLogEntry = context.getReplicatedLog().get(N);
- if (replicatedLogEntry != null &&
- replicatedLogEntry.getTerm() == currentTerm()) {
+ if (replicatedLogEntry == null) {
+ LOG.debug("{}: ReplicatedLogEntry not found for index {} - snapshotIndex: {}, journal size: {}",
+ logName(), N, context.getReplicatedLog().getSnapshotIndex(), context.getReplicatedLog().size());
+ break;
+ }
+
+ // Don't update the commit index if the log entry is from a previous term, as per §5.4.1:
+ // "Raft never commits log entries from previous terms by counting replicas".
+ // However we keep looping so we can make progress when new entries in the current term
+ // reach consensus, as per §5.4.1: "once an entry from the current term is committed by
+ // counting replicas, then all prior entries are committed indirectly".
+ if (replicatedLogEntry.getTerm() == currentTerm()) {
+ LOG.trace("{}: Setting commit index to {}", logName(), N);
context.setCommitIndex(N);
+ } else {
+ LOG.debug("{}: Not updating commit index to {} - retrieved log entry with index {}, term {} does not match the current term {}",
+ logName(), N, replicatedLogEntry.getIndex(), replicatedLogEntry.getTerm(), currentTerm());
}
} else {
+ LOG.trace("{}: minReplicationCount not reached, actual {} - breaking", logName(), replicatedCount);
break;
}
}
// Apply the change to the state machine
if (context.getCommitIndex() > context.getLastApplied()) {
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: handleAppendEntriesReply from {}: applying to log - commitIndex: {}, lastAppliedIndex: {}",
+ logName(), followerId, context.getCommitIndex(), context.getLastApplied());
+ }
+
applyLogToStateMachine(context.getCommitIndex());
}
- if (!context.isSnapshotCaptureInitiated()) {
+ if (!context.getSnapshotManager().isCapturing()) {
purgeInMemoryLog();
}
//Send the next log entry immediately, if possible, no need to wait for heartbeat to trigger that event
- sendUpdatesToFollower(followerId, followerLogInformation, false);
+ sendUpdatesToFollower(followerId, followerLogInformation, false, !updated);
+
return this;
}
+ private boolean updateFollowerLogInformation(FollowerLogInformation followerLogInformation,
+ AppendEntriesReply appendEntriesReply) {
+ boolean updated = followerLogInformation.setMatchIndex(appendEntriesReply.getLogLastIndex());
+ updated = followerLogInformation.setNextIndex(appendEntriesReply.getLogLastIndex() + 1) || updated;
+
+ if(updated && LOG.isDebugEnabled()) {
+ LOG.debug("{}: handleAppendEntriesReply - FollowerLogInformation for {} updated: matchIndex: {}, nextIndex: {}",
+ logName(), followerLogInformation.getId(), followerLogInformation.getMatchIndex(),
+ followerLogInformation.getNextIndex());
+ }
+ return updated;
+ }
+
private void purgeInMemoryLog() {
- //find the lowest index across followers which has been replicated to all. -1 if there are no followers.
+ //find the lowest index across followers which has been replicated to all.
+ // lastApplied if there are no followers, so that we keep clearing the log for single-node
// we would delete the in-mem log from that index on, in-order to minimize mem usage
// we would also share this info thru AE with the followers so that they can delete their log entries as well.
- long minReplicatedToAllIndex = followerToLog.isEmpty() ? -1 : Long.MAX_VALUE;
+ long minReplicatedToAllIndex = followerToLog.isEmpty() ? context.getLastApplied() : Long.MAX_VALUE;
for (FollowerLogInformation info : followerToLog.values()) {
minReplicatedToAllIndex = Math.min(minReplicatedToAllIndex, info.getMatchIndex());
}
- replicatedToAllIndex = fakeSnapshot(minReplicatedToAllIndex, replicatedToAllIndex);
+ super.performSnapshotWithoutCapture(minReplicatedToAllIndex);
}
@Override
protected ClientRequestTracker removeClientRequestTracker(long logIndex) {
- final Iterator<ClientRequestTracker> it = trackerList.iterator();
+ final Iterator<ClientRequestTracker> it = trackers.iterator();
while (it.hasNext()) {
final ClientRequestTracker t = it.next();
if (t.getIndex() == logIndex) {
return null;
}
- @Override
- protected ClientRequestTracker findClientRequestTracker(long logIndex) {
- for (ClientRequestTracker tracker : trackerList) {
- if (tracker.getIndex() == logIndex) {
- return tracker;
- }
- }
- return null;
- }
-
@Override
protected RaftActorBehavior handleRequestVoteReply(ActorRef sender,
RequestVoteReply requestVoteReply) {
return this;
}
- @Override
- public RaftState state() {
- return RaftState.Leader;
- }
+ protected void beforeSendHeartbeat(){}
@Override
- public RaftActorBehavior handleMessage(ActorRef sender, Object originalMessage) {
+ public RaftActorBehavior handleMessage(ActorRef sender, Object message) {
Preconditions.checkNotNull(sender, "sender should not be null");
- Object message = fromSerializableMessage(originalMessage);
-
if (message instanceof RaftRPC) {
RaftRPC rpc = (RaftRPC) message;
// If RPC request or response contains term T > currentTerm:
// set currentTerm = T, convert to follower (§5.1)
// This applies to all RPC messages and responses
if (rpc.getTerm() > context.getTermInformation().getCurrentTerm()) {
- LOG.debug("{}: Term {} in \"{}\" message is greater than leader's term {}", context.getId(),
- rpc.getTerm(), rpc, context.getTermInformation().getCurrentTerm());
+ LOG.debug("{}: Term {} in \"{}\" message is greater than leader's term {} - switching to Follower",
+ logName(), rpc.getTerm(), rpc, context.getTermInformation().getCurrentTerm());
context.getTermInformation().updateAndPersist(rpc.getTerm(), null);
- return switchBehavior(new Follower(context));
+ return internalSwitchBehavior(RaftState.Follower);
}
}
- try {
- if (message instanceof SendHeartBeat) {
- sendHeartBeat();
- return this;
-
- } else if(message instanceof InitiateInstallSnapshot) {
- installSnapshotIfNeeded();
-
- } else if(message instanceof SendInstallSnapshot) {
- // received from RaftActor
- setSnapshot(Optional.of(((SendInstallSnapshot) message).getSnapshot()));
- sendInstallSnapshot();
-
- } else if (message instanceof Replicate) {
- replicate((Replicate) message);
-
- } else if (message instanceof InstallSnapshotReply){
- handleInstallSnapshotReply((InstallSnapshotReply) message);
-
- }
- } finally {
+ if (message instanceof SendHeartBeat) {
+ beforeSendHeartbeat();
+ sendHeartBeat();
scheduleHeartBeat(context.getConfigParams().getHeartBeatInterval());
+ } else if(message instanceof SendInstallSnapshot) {
+ // received from RaftActor
+ setSnapshot(((SendInstallSnapshot) message).getSnapshot());
+ sendInstallSnapshot();
+ } else if (message instanceof Replicate) {
+ replicate((Replicate) message);
+ } else if (message instanceof InstallSnapshotReply) {
+ handleInstallSnapshotReply((InstallSnapshotReply) message);
+ } else {
+ return super.handleMessage(sender, message);
}
- return super.handleMessage(sender, message);
+ return this;
}
private void handleInstallSnapshotReply(InstallSnapshotReply reply) {
+ LOG.debug("{}: handleInstallSnapshotReply: {}", logName(), reply);
+
String followerId = reply.getFollowerId();
FollowerToSnapshot followerToSnapshot = mapFollowerToSnapshot.get(followerId);
if (followerToSnapshot == null) {
- LOG.error("{}: FollowerId {} in InstallSnapshotReply not known to Leader",
- context.getId(), followerId);
+ LOG.error("{}: FollowerToSnapshot not found for follower {} in InstallSnapshotReply",
+ logName(), followerId);
return;
}
FollowerLogInformation followerLogInformation = followerToLog.get(followerId);
+ if(followerLogInformation == null) {
+ // This can happen during AddServer if it times out.
+ LOG.error("{}: FollowerLogInformation not found for follower {} in InstallSnapshotReply",
+ logName(), followerId);
+ mapFollowerToSnapshot.remove(followerId);
+ return;
+ }
+
followerLogInformation.markFollowerActive();
if (followerToSnapshot.getChunkIndex() == reply.getChunkIndex()) {
//this was the last chunk reply
if(LOG.isDebugEnabled()) {
LOG.debug("{}: InstallSnapshotReply received, " +
- "last chunk received, Chunk:{}. Follower:{} Setting nextIndex:{}",
- context.getId(), reply.getChunkIndex(), followerId,
+ "last chunk received, Chunk: {}. Follower: {} Setting nextIndex: {}",
+ logName(), reply.getChunkIndex(), followerId,
context.getReplicatedLog().getSnapshotIndex() + 1
);
}
- followerLogInformation.setMatchIndex(
- context.getReplicatedLog().getSnapshotIndex());
- followerLogInformation.setNextIndex(
- context.getReplicatedLog().getSnapshotIndex() + 1);
+ long followerMatchIndex = snapshot.get().getLastIncludedIndex();
+ followerLogInformation.setMatchIndex(followerMatchIndex);
+ followerLogInformation.setNextIndex(followerMatchIndex + 1);
mapFollowerToSnapshot.remove(followerId);
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: followerToLog.get(followerId).getNextIndex()=" +
- context.getId(), followerToLog.get(followerId).getNextIndex());
- }
+ LOG.debug("{}: follower: {}, matchIndex set to {}, nextIndex set to {}",
+ logName(), followerId, followerLogInformation.getMatchIndex(),
+ followerLogInformation.getNextIndex());
if (mapFollowerToSnapshot.isEmpty()) {
// once there are no pending followers receiving snapshots
// we can remove snapshot from the memory
- setSnapshot(Optional.<ByteString>absent());
+ setSnapshot(null);
}
wasLastChunk = true;
-
+ if(context.getPeerInfo(followerId).getVotingState() == VotingState.VOTING_NOT_INITIALIZED){
+ UnInitializedFollowerSnapshotReply unInitFollowerSnapshotSuccess =
+ new UnInitializedFollowerSnapshotReply(followerId);
+ context.getActor().tell(unInitFollowerSnapshotSuccess, context.getActor());
+ LOG.debug("Sent message UnInitializedFollowerSnapshotReply to self");
+ }
} else {
followerToSnapshot.markSendStatus(true);
}
} else {
LOG.info("{}: InstallSnapshotReply received sending snapshot chunk failed, Will retry, Chunk: {}",
- context.getId(), reply.getChunkIndex());
+ logName(), reply.getChunkIndex());
followerToSnapshot.markSendStatus(false);
}
- if (!wasLastChunk && followerToSnapshot.canSendNextChunk()) {
+ if (wasLastChunk && !context.getSnapshotManager().isCapturing()) {
+ // Since the follower is now caught up try to purge the log.
+ purgeInMemoryLog();
+ } else if (!wasLastChunk && followerToSnapshot.canSendNextChunk()) {
ActorSelection followerActor = context.getPeerActorSelection(followerId);
if(followerActor != null) {
sendSnapshotChunk(followerActor, followerId);
} else {
LOG.error("{}: Chunk index {} in InstallSnapshotReply from follower {} does not match expected index {}",
- context.getId(), reply.getChunkIndex(), followerId,
+ logName(), reply.getChunkIndex(), followerId,
followerToSnapshot.getChunkIndex());
if(reply.getChunkIndex() == INVALID_CHUNK_INDEX){
private void replicate(Replicate replicate) {
long logIndex = replicate.getReplicatedLogEntry().getIndex();
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: Replicate message {}", context.getId(), logIndex);
- }
+ LOG.debug("{}: Replicate message: identifier: {}, logIndex: {}, payload: {}", logName(),
+ replicate.getIdentifier(), logIndex, replicate.getReplicatedLogEntry().getData().getClass());
// Create a tracker entry we will use this later to notify the
// client actor
- trackerList.add(
- new ClientRequestTrackerImpl(replicate.getClientActor(),
- replicate.getIdentifier(),
- logIndex)
- );
+ if(replicate.getClientActor() != null) {
+ trackers.add(new ClientRequestTrackerImpl(replicate.getClientActor(), replicate.getIdentifier(),
+ logIndex));
+ }
- if (followerToLog.isEmpty()) {
+ boolean applyModificationToState = !context.anyVotingPeers()
+ || context.getRaftPolicy().applyModificationToStateBeforeConsensus();
+
+ if(applyModificationToState){
context.setCommitIndex(logIndex);
applyLogToStateMachine(logIndex);
- } else {
- sendAppendEntries();
+ }
+
+ if (!followerToLog.isEmpty()) {
+ sendAppendEntries(0, false);
}
}
- private void sendAppendEntries() {
+ protected void sendAppendEntries(long timeSinceLastActivityInterval, boolean isHeartbeat) {
// Send an AppendEntries to all followers
- long heartbeatInterval = context.getConfigParams().getHeartBeatInterval().toMillis();
for (Entry<String, FollowerLogInformation> e : followerToLog.entrySet()) {
final String followerId = e.getKey();
final FollowerLogInformation followerLogInformation = e.getValue();
// This checks helps not to send a repeat message to the follower
- if(followerLogInformation.timeSinceLastActivity() >= heartbeatInterval) {
- sendUpdatesToFollower(followerId, followerLogInformation, true);
+ if(!followerLogInformation.isFollowerActive() ||
+ followerLogInformation.timeSinceLastActivity() >= timeSinceLastActivityInterval) {
+ sendUpdatesToFollower(followerId, followerLogInformation, true, isHeartbeat);
}
}
}
*/
private void sendUpdatesToFollower(String followerId, FollowerLogInformation followerLogInformation,
- boolean sendHeartbeat) {
+ boolean sendHeartbeat, boolean isHeartbeat) {
ActorSelection followerActor = context.getPeerActorSelection(followerId);
if (followerActor != null) {
long followerNextIndex = followerLogInformation.getNextIndex();
boolean isFollowerActive = followerLogInformation.isFollowerActive();
+ boolean sendAppendEntries = false;
+ List<ReplicatedLogEntry> entries = Collections.emptyList();
if (mapFollowerToSnapshot.get(followerId) != null) {
// if install snapshot is in process , then sent next chunk if possible
sendSnapshotChunk(followerActor, followerId);
} else if(sendHeartbeat) {
// we send a heartbeat even if we have not received a reply for the last chunk
- sendAppendEntriesToFollower(followerActor, followerLogInformation.getNextIndex(),
- Collections.<ReplicatedLogEntry>emptyList(), followerId);
+ sendAppendEntries = true;
}
} else {
long leaderLastIndex = context.getReplicatedLog().lastIndex();
long leaderSnapShotIndex = context.getReplicatedLog().getSnapshotIndex();
- if (isFollowerActive &&
- context.getReplicatedLog().isPresent(followerNextIndex)) {
- // FIXME : Sending one entry at a time
- final List<ReplicatedLogEntry> entries = context.getReplicatedLog().getFrom(followerNextIndex, 1);
- sendAppendEntriesToFollower(followerActor, followerNextIndex, entries, followerId);
+ if((!isHeartbeat && LOG.isDebugEnabled()) || LOG.isTraceEnabled()) {
+ LOG.debug("{}: Checking sendAppendEntries for follower {}: active: {}, followerNextIndex: {}, leaderLastIndex: {}, leaderSnapShotIndex: {}",
+ logName(), followerId, isFollowerActive, followerNextIndex, leaderLastIndex, leaderSnapShotIndex);
+ }
+
+ if (isFollowerActive && context.getReplicatedLog().isPresent(followerNextIndex)) {
+
+ LOG.debug("{}: sendAppendEntries: {} is present for follower {}", logName(),
+ followerNextIndex, followerId);
+ if(followerLogInformation.okToReplicate()) {
+ // Try to send all the entries in the journal but not exceeding the max data size
+ // for a single AppendEntries message.
+ int maxEntries = (int) context.getReplicatedLog().size();
+ entries = context.getReplicatedLog().getFrom(followerNextIndex, maxEntries,
+ context.getConfigParams().getSnapshotChunkSize());
+ sendAppendEntries = true;
+ }
} else if (isFollowerActive && followerNextIndex >= 0 &&
- leaderLastIndex >= followerNextIndex) {
+ leaderLastIndex > followerNextIndex && !context.getSnapshotManager().isCapturing()) {
// if the followers next index is not present in the leaders log, and
// if the follower is just not starting and if leader's index is more than followers index
// then snapshot should be sent
if (LOG.isDebugEnabled()) {
- LOG.debug("InitiateInstallSnapshot to follower:{}," +
- "follower-nextIndex:{}, leader-snapshot-index:{}, " +
- "leader-last-index:{}", followerId,
- followerNextIndex, leaderSnapShotIndex, leaderLastIndex
- );
+ LOG.debug(String.format("%s: InitiateInstallSnapshot to follower: %s, " +
+ "follower-nextIndex: %d, leader-snapshot-index: %d, " +
+ "leader-last-index: %d", logName(), followerId,
+ followerNextIndex, leaderSnapShotIndex, leaderLastIndex));
}
- actor().tell(new InitiateInstallSnapshot(), actor());
// Send heartbeat to follower whenever install snapshot is initiated.
- sendAppendEntriesToFollower(followerActor, followerLogInformation.getNextIndex(),
- Collections.<ReplicatedLogEntry>emptyList(), followerId);
+ sendAppendEntries = true;
+ if (canInstallSnapshot(followerNextIndex)) {
+ initiateCaptureSnapshot(followerId);
+ }
} else if(sendHeartbeat) {
- //we send an AppendEntries, even if the follower is inactive
+ // we send an AppendEntries, even if the follower is inactive
// in-order to update the followers timestamp, in case it becomes active again
- sendAppendEntriesToFollower(followerActor, followerLogInformation.getNextIndex(),
- Collections.<ReplicatedLogEntry>emptyList(), followerId);
+ sendAppendEntries = true;
}
}
+
+ if(sendAppendEntries) {
+ sendAppendEntriesToFollower(followerActor, followerNextIndex,
+ entries, followerId);
+ }
}
}
private void sendAppendEntriesToFollower(ActorSelection followerActor, long followerNextIndex,
List<ReplicatedLogEntry> entries, String followerId) {
AppendEntries appendEntries = new AppendEntries(currentTerm(), context.getId(),
- prevLogIndex(followerNextIndex),
- prevLogTerm(followerNextIndex), entries,
- context.getCommitIndex(), replicatedToAllIndex);
+ getLogEntryIndex(followerNextIndex - 1),
+ getLogEntryTerm(followerNextIndex - 1), entries,
+ context.getCommitIndex(), super.getReplicatedToAllIndex(), context.getPayloadVersion());
- if(!entries.isEmpty()) {
- LOG.debug("{}: Sending AppendEntries to follower {}: {}", context.getId(), followerId,
+ if(!entries.isEmpty() || LOG.isTraceEnabled()) {
+ LOG.debug("{}: Sending AppendEntries to follower {}: {}", logName(), followerId,
appendEntries);
}
- followerActor.tell(appendEntries.toSerializable(), actor());
+ followerActor.tell(appendEntries, actor());
}
/**
- * An installSnapshot is scheduled at a interval that is a multiple of
- * a HEARTBEAT_INTERVAL. This is to avoid the need to check for installing
- * snapshots at every heartbeat.
- *
* Install Snapshot works as follows
- * 1. Leader sends a InitiateInstallSnapshot message to self
- * 2. Leader then initiates the capture snapshot by sending a CaptureSnapshot message to actor
- * 3. RaftActor on receipt of the CaptureSnapshotReply (from Shard), stores the received snapshot in the replicated log
+ * 1. Leader initiates the capture snapshot by sending a CaptureSnapshot message to actor
+ * 2. RaftActor on receipt of the CaptureSnapshotReply (from Shard), stores the received snapshot in the replicated log
* and makes a call to Leader's handleMessage , with SendInstallSnapshot message.
- * 4. Leader , picks the snapshot from im-mem ReplicatedLog and sends it in chunks to the Follower
- * 5. On complete, Follower sends back a InstallSnapshotReply.
- * 6. On receipt of the InstallSnapshotReply for the last chunk, Leader marks the install complete for that follower
+ * 3. Leader , picks the snapshot from im-mem ReplicatedLog and sends it in chunks to the Follower
+ * 4. On complete, Follower sends back a InstallSnapshotReply.
+ * 5. On receipt of the InstallSnapshotReply for the last chunk, Leader marks the install complete for that follower
* and replenishes the memory by deleting the snapshot in Replicated log.
- *
+ * 6. If another follower requires a snapshot and a snapshot has been collected (via CaptureSnapshotReply)
+ * then send the existing snapshot in chunks to the follower.
+ * @param followerId
*/
- private void installSnapshotIfNeeded() {
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: installSnapshotIfNeeded, followers {}", context.getId(), followerToLog.keySet());
- }
-
- for (Entry<String, FollowerLogInformation> e : followerToLog.entrySet()) {
- final ActorSelection followerActor = context.getPeerActorSelection(e.getKey());
-
- if (followerActor != null) {
- long nextIndex = e.getValue().getNextIndex();
-
- if (!context.getReplicatedLog().isPresent(nextIndex) &&
- context.getReplicatedLog().isInSnapshot(nextIndex)) {
- LOG.info("{}: {} follower needs a snapshot install", context.getId(), e.getKey());
- if (snapshot.isPresent()) {
- // if a snapshot is present in the memory, most likely another install is in progress
- // no need to capture snapshot
- sendSnapshotChunk(followerActor, e.getKey());
-
- } else {
- initiateCaptureSnapshot();
- //we just need 1 follower who would need snapshot to be installed.
- // when we have the snapshot captured, we would again check (in SendInstallSnapshot)
- // who needs an install and send to all who need
- break;
- }
-
- }
- }
+ public boolean initiateCaptureSnapshot(String followerId) {
+ if (snapshot.isPresent()) {
+ // if a snapshot is present in the memory, most likely another install is in progress
+ // no need to capture snapshot.
+ // This could happen if another follower needs an install when one is going on.
+ final ActorSelection followerActor = context.getPeerActorSelection(followerId);
+ sendSnapshotChunk(followerActor, followerId);
+ return true;
+ } else {
+ return context.getSnapshotManager().captureToInstall(context.getReplicatedLog().last(),
+ this.getReplicatedToAllIndex(), followerId);
}
}
- // on every install snapshot, we try to capture the snapshot.
- // Once a capture is going on, another one issued will get ignored by RaftActor.
- private void initiateCaptureSnapshot() {
- LOG.info("{}: Initiating Snapshot Capture to Install Snapshot, Leader:{}", context.getId(), getLeaderId());
- ReplicatedLogEntry lastAppliedEntry = context.getReplicatedLog().get(context.getLastApplied());
- long lastAppliedIndex = -1;
- long lastAppliedTerm = -1;
+ private boolean canInstallSnapshot(long nextIndex){
+ // If the follower's nextIndex is -1 then we might as well send it a snapshot
+ // Otherwise send it a snapshot only if the nextIndex is not present in the log but is present
+ // in the snapshot
+ return nextIndex == -1 ||
+ (!context.getReplicatedLog().isPresent(nextIndex)
+ && context.getReplicatedLog().isInSnapshot(nextIndex));
- if (lastAppliedEntry != null) {
- lastAppliedIndex = lastAppliedEntry.getIndex();
- lastAppliedTerm = lastAppliedEntry.getTerm();
- } else if (context.getReplicatedLog().getSnapshotIndex() > -1) {
- lastAppliedIndex = context.getReplicatedLog().getSnapshotIndex();
- lastAppliedTerm = context.getReplicatedLog().getSnapshotTerm();
- }
-
- boolean isInstallSnapshotInitiated = true;
- actor().tell(new CaptureSnapshot(lastIndex(), lastTerm(),
- lastAppliedIndex, lastAppliedTerm, isInstallSnapshotInitiated),
- actor());
}
private void sendInstallSnapshot() {
+ LOG.debug("{}: sendInstallSnapshot", logName());
for (Entry<String, FollowerLogInformation> e : followerToLog.entrySet()) {
- ActorSelection followerActor = context.getPeerActorSelection(e.getKey());
+ String followerId = e.getKey();
+ ActorSelection followerActor = context.getPeerActorSelection(followerId);
+ FollowerLogInformation followerLogInfo = e.getValue();
if (followerActor != null) {
- long nextIndex = e.getValue().getNextIndex();
-
- if (!context.getReplicatedLog().isPresent(nextIndex) &&
- context.getReplicatedLog().isInSnapshot(nextIndex)) {
- sendSnapshotChunk(followerActor, e.getKey());
+ long nextIndex = followerLogInfo.getNextIndex();
+ if (context.getPeerInfo(followerId).getVotingState() == VotingState.VOTING_NOT_INITIALIZED ||
+ canInstallSnapshot(nextIndex)) {
+ sendSnapshotChunk(followerActor, followerId);
}
}
}
private void sendSnapshotChunk(ActorSelection followerActor, String followerId) {
try {
if (snapshot.isPresent()) {
- ByteString nextSnapshotChunk = getNextSnapshotChunk(followerId,snapshot.get());
+ byte[] nextSnapshotChunk = getNextSnapshotChunk(followerId, snapshot.get().getSnapshotBytes());
// Note: the previous call to getNextSnapshotChunk has the side-effect of adding
// followerId to the followerToSnapshot map.
FollowerToSnapshot followerToSnapshot = mapFollowerToSnapshot.get(followerId);
+ int nextChunkIndex = followerToSnapshot.incrementChunkIndex();
+ Optional<ServerConfigurationPayload> serverConfig = Optional.absent();
+ if(followerToSnapshot.isLastChunk(nextChunkIndex)) {
+ serverConfig = Optional.fromNullable(context.getPeerServerInfo(true));
+ }
+
followerActor.tell(
new InstallSnapshot(currentTerm(), context.getId(),
- context.getReplicatedLog().getSnapshotIndex(),
- context.getReplicatedLog().getSnapshotTerm(),
+ snapshot.get().getLastIncludedIndex(),
+ snapshot.get().getLastIncludedTerm(),
nextSnapshotChunk,
- followerToSnapshot.incrementChunkIndex(),
+ nextChunkIndex,
followerToSnapshot.getTotalChunks(),
- Optional.of(followerToSnapshot.getLastChunkHashCode())
- ).toSerializable(),
+ Optional.of(followerToSnapshot.getLastChunkHashCode()),
+ serverConfig
+ ).toSerializable(followerToLog.get(followerId).getRaftVersion()),
actor()
);
- LOG.info("{}: InstallSnapshot sent to follower {}, Chunk: {}/{}",
- context.getId(), followerActor.path(),
- followerToSnapshot.getChunkIndex(),
- followerToSnapshot.getTotalChunks());
+
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: InstallSnapshot sent to follower {}, Chunk: {}/{}",
+ logName(), followerActor.path(), followerToSnapshot.getChunkIndex(),
+ followerToSnapshot.getTotalChunks());
+ }
}
} catch (IOException e) {
- LOG.error("{}: InstallSnapshot failed for Leader.", context.getId(), e);
+ LOG.error("{}: InstallSnapshot failed for Leader.", logName(), e);
}
}
* Acccepts snaphot as ByteString, enters into map for future chunks
* creates and return a ByteString chunk
*/
- private ByteString getNextSnapshotChunk(String followerId, ByteString snapshotBytes) throws IOException {
+ private byte[] getNextSnapshotChunk(String followerId, ByteString snapshotBytes) throws IOException {
FollowerToSnapshot followerToSnapshot = mapFollowerToSnapshot.get(followerId);
if (followerToSnapshot == null) {
followerToSnapshot = new FollowerToSnapshot(snapshotBytes);
mapFollowerToSnapshot.put(followerId, followerToSnapshot);
}
- ByteString nextChunk = followerToSnapshot.getNextChunk();
- if (LOG.isDebugEnabled()) {
- LOG.debug("{}: Leader's snapshot nextChunk size:{}", context.getId(), nextChunk.size());
- }
+ byte[] nextChunk = followerToSnapshot.getNextChunk();
+
+ LOG.debug("{}: next snapshot chunk size for follower {}: {}", logName(), followerId, nextChunk.length);
+
return nextChunk;
}
private void sendHeartBeat() {
if (!followerToLog.isEmpty()) {
- sendAppendEntries();
+ LOG.trace("{}: Sending heartbeat", logName());
+ sendAppendEntries(context.getConfigParams().getHeartBeatInterval().toMillis(), true);
}
}
// need to be sent if there are other messages being sent to the remote
// actor.
heartbeatSchedule = context.getActorSystem().scheduler().scheduleOnce(
- interval, context.getActor(), new SendHeartBeat(),
+ interval, context.getActor(), SendHeartBeat.INSTANCE,
context.getActorSystem().dispatcher(), context.getActor());
}
@Override
- public void close() throws Exception {
+ public void close() {
stopHeartBeat();
}
@Override
- public String getLeaderId() {
+ public final String getLeaderId() {
return context.getId();
}
+ @Override
+ public final short getLeaderPayloadVersion() {
+ return context.getPayloadVersion();
+ }
+
protected boolean isLeaderIsolated() {
- int minPresent = minIsolatedLeaderPeerCount;
+ int minPresent = getMinIsolatedLeaderPeerCount();
for (FollowerLogInformation followerLogInformation : followerToLog.values()) {
- if (followerLogInformation.isFollowerActive()) {
+ final PeerInfo peerInfo = context.getPeerInfo(followerLogInformation.getId());
+ if(peerInfo != null && peerInfo.isVoting() && followerLogInformation.isFollowerActive()) {
--minPresent;
if (minPresent == 0) {
- break;
+ return false;
}
}
}
- return (minPresent != 0);
+ return minPresent != 0;
}
/**
public FollowerToSnapshot(ByteString snapshotBytes) {
this.snapshotBytes = snapshotBytes;
int size = snapshotBytes.size();
- totalChunks = ( size / context.getConfigParams().getSnapshotChunkSize()) +
- ((size % context.getConfigParams().getSnapshotChunkSize()) > 0 ? 1 : 0);
+ totalChunks = (size / context.getConfigParams().getSnapshotChunkSize()) +
+ (size % context.getConfigParams().getSnapshotChunkSize() > 0 ? 1 : 0);
if(LOG.isDebugEnabled()) {
LOG.debug("{}: Snapshot {} bytes, total chunks to send:{}",
- context.getId(), size, totalChunks);
+ logName(), size, totalChunks);
}
replyReceivedForOffset = -1;
chunkIndex = AbstractLeader.FIRST_CHUNK_INDEX;
}
}
- public ByteString getNextChunk() {
+ public byte[] getNextChunk() {
int snapshotLength = getSnapshotBytes().size();
int start = incrementOffset();
int size = context.getConfigParams().getSnapshotChunkSize();
if (context.getConfigParams().getSnapshotChunkSize() > snapshotLength) {
size = snapshotLength;
- } else {
- if ((start + context.getConfigParams().getSnapshotChunkSize()) > snapshotLength) {
- size = snapshotLength - start;
- }
+ } else if ((start + context.getConfigParams().getSnapshotChunkSize()) > snapshotLength) {
+ size = snapshotLength - start;
}
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: Next chunk: length={}, offset={},size={}", context.getId(),
- snapshotLength, start, size);
- }
- ByteString substring = getSnapshotBytes().substring(start, start + size);
- nextChunkHashCode = substring.hashCode();
- return substring;
+ byte[] nextChunk = new byte[size];
+ getSnapshotBytes().copyTo(nextChunk, start, 0, size);
+ nextChunkHashCode = Arrays.hashCode(nextChunk);
+
+ LOG.debug("{}: Next chunk: total length={}, offset={}, size={}, hashCode={}", logName(),
+ snapshotLength, start, size, nextChunkHashCode);
+ return nextChunk;
}
/**
public int followerLogSize() {
return followerToLog.size();
}
+
+ private static class SnapshotHolder {
+ private final long lastIncludedTerm;
+ private final long lastIncludedIndex;
+ private final ByteString snapshotBytes;
+
+ SnapshotHolder(Snapshot snapshot) {
+ this.lastIncludedTerm = snapshot.getLastAppliedTerm();
+ this.lastIncludedIndex = snapshot.getLastAppliedIndex();
+ this.snapshotBytes = ByteString.copyFrom(snapshot.getState());
+ }
+
+ long getLastIncludedTerm() {
+ return lastIncludedTerm;
+ }
+
+ long getLastIncludedIndex() {
+ return lastIncludedIndex;
+ }
+
+ ByteString getSnapshotBytes() {
+ return snapshotBytes;
+ }
+ }
}
Code Review / controller.git / blobdiff