snapshotHolder = Optional.absent();
private int minReplicationCount;
protected AbstractLeader(RaftActorContext context, RaftState state,
@Nullable AbstractLeader initializeFromLeader) {
super(context, state);
- if(initializeFromLeader != null) {
+ if (initializeFromLeader != null) {
followerToLog.putAll(initializeFromLeader.followerToLog);
- snapshot = initializeFromLeader.snapshot;
+ snapshotHolder = initializeFromLeader.snapshotHolder;
trackers.addAll(initializeFromLeader.trackers);
} else {
- for(PeerInfo peerInfo: context.getPeers()) {
+ for (PeerInfo peerInfo: context.getPeers()) {
FollowerLogInformation followerLogInformation = new FollowerLogInformationImpl(peerInfo, -1, context);
followerToLog.put(peerInfo.getId(), followerLogInformation);
}
}
- LOG.debug("{}: Election: Leader has following peers: {}", logName(), getFollowerIds());
+ log.debug("{}: Election: Leader has following peers: {}", logName(), getFollowerIds());
updateMinReplicaCount();
@@ -133,7 +135,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
context.getPeerInfo(followerId), -1, context);
followerToLog.put(followerId, followerLogInformation);
- if(heartbeatSchedule == null) {
+ if (heartbeatSchedule == null) {
scheduleHeartBeat(context.getConfigParams().getHeartBeatInterval());
}
}
@@ -144,8 +146,8 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
public void updateMinReplicaCount() {
int numVoting = 0;
- for(PeerInfo peer: context.getPeers()) {
- if(peer.isVoting()) {
+ for (PeerInfo peer: context.getPeers()) {
+ if (peer.isVoting()) {
numVoting++;
}
}
@@ -153,7 +155,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
minReplicationCount = getMajorityVoteCount(numVoting);
}
- protected int getMinIsolatedLeaderPeerCount(){
+ 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
@@ -161,51 +163,45 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
//2 peers = 2 votesRequired , minIsolatedLeaderPeerCount = 1
//4 peers = 3 votesRequired, minIsolatedLeaderPeerCount = 2
- return minReplicationCount > 0 ? (minReplicationCount - 1) : 0;
+ return minReplicationCount > 0 ? minReplicationCount - 1 : 0;
}
@VisibleForTesting
- void setSnapshot(@Nullable Snapshot snapshot) {
- if(snapshot != null) {
- this.snapshot = Optional.of(new SnapshotHolder(snapshot));
- } else {
- this.snapshot = Optional.absent();
- }
+ void setSnapshot(@Nullable SnapshotHolder snapshotHolder) {
+ this.snapshotHolder = Optional.fromNullable(snapshotHolder);
}
@VisibleForTesting
boolean hasSnapshot() {
- return snapshot.isPresent();
+ return snapshotHolder.isPresent();
}
@Override
protected RaftActorBehavior handleAppendEntries(ActorRef sender,
AppendEntries appendEntries) {
- LOG.debug("{}: handleAppendEntries: {}", logName(), appendEntries);
+ log.debug("{}: handleAppendEntries: {}", logName(), appendEntries);
return this;
}
@Override
protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender, AppendEntriesReply appendEntriesReply) {
- if(LOG.isTraceEnabled()) {
- LOG.trace("{}: handleAppendEntriesReply: {}", logName(), appendEntriesReply);
- }
+ log.trace("{}: handleAppendEntriesReply: {}", logName(), appendEntriesReply);
// Update the FollowerLogInformation
String followerId = appendEntriesReply.getFollowerId();
FollowerLogInformation followerLogInformation = followerToLog.get(followerId);
- if(followerLogInformation == null){
- LOG.error("{}: handleAppendEntriesReply - unknown follower {}", logName(), followerId);
+ if (followerLogInformation == null) {
+ log.error("{}: handleAppendEntriesReply - unknown follower {}", logName(), followerId);
return this;
}
- if(followerLogInformation.timeSinceLastActivity() >
- context.getConfigParams().getElectionTimeOutInterval().toMillis()) {
- LOG.warn("{} : handleAppendEntriesReply delayed beyond election timeout, " +
- "appendEntriesReply : {}, timeSinceLastActivity : {}, lastApplied : {}, commitIndex : {}",
+ 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());
}
@@ -217,7 +213,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
long followerLastLogIndex = appendEntriesReply.getLogLastIndex();
long followersLastLogTermInLeadersLog = getLogEntryTerm(followerLastLogIndex);
boolean updated = false;
- if(appendEntriesReply.getLogLastIndex() > context.getReplicatedLog().lastIndex()) {
+ 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
@@ -231,9 +227,10 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
// 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());
+ log.info("{}: handleAppendEntriesReply: follower {} lastIndex {} is ahead of our lastIndex {} "
+ + "(snapshotIndex {}) - forcing install snaphot", logName(), followerLogInformation.getId(),
+ appendEntriesReply.getLogLastIndex(), context.getReplicatedLog().lastIndex(),
+ context.getReplicatedLog().getSnapshotIndex());
followerLogInformation.setMatchIndex(-1);
followerLogInformation.setNextIndex(-1);
@@ -242,8 +239,8 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
updated = true;
} else if (appendEntriesReply.isSuccess()) {
- if (followerLastLogIndex >= 0 && followersLastLogTermInLeadersLog >= 0 &&
- followersLastLogTermInLeadersLog != appendEntriesReply.getLogLastTerm()) {
+ if (followerLastLogIndex >= 0 && followersLastLogTermInLeadersLog >= 0
+ && followersLastLogTermInLeadersLog != appendEntriesReply.getLogLastTerm()) {
// The follower's last entry is present in the leader's journal but the terms don't match so the
// follower has a conflicting entry. Since the follower didn't report that it's out of sync, this means
// either the previous leader entry sent didn't conflict or the previous leader entry is in the snapshot
@@ -255,17 +252,18 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
followerLogInformation.setNextIndex(followerLastLogIndex - 1);
updated = true;
- LOG.debug("{}: handleAppendEntriesReply: follower {} last log term {} for index {} conflicts with the " +
- "leader's {} - set the follower's next index to {}",
- logName(), followerId, appendEntriesReply.getLogLastTerm(), appendEntriesReply.getLogLastIndex(),
+ log.info("{}: handleAppendEntriesReply: follower {} last log term {} for index {} conflicts with the "
+ + "leader's {} - set the follower's next index to {}", logName(),
+ followerId, appendEntriesReply.getLogLastTerm(), appendEntriesReply.getLogLastIndex(),
followersLastLogTermInLeadersLog, followerLogInformation.getNextIndex());
} else {
updated = updateFollowerLogInformation(followerLogInformation, appendEntriesReply);
}
} else {
- LOG.debug("{}: handleAppendEntriesReply: received unsuccessful reply: {}", logName(), appendEntriesReply);
+ log.info("{}: handleAppendEntriesReply - received unsuccessful reply: {}, leader snapshotIndex: {}",
+ logName(), appendEntriesReply, context.getReplicatedLog().getSnapshotIndex());
- if(appendEntriesReply.isForceInstallSnapshot()) {
+ 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);
@@ -273,86 +271,110 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
// Force initiate a snapshot capture
initiateCaptureSnapshot(followerId);
- } else if(followerLastLogIndex < 0 || followersLastLogTermInLeadersLog >= 0 &&
- followersLastLogTermInLeadersLog == appendEntriesReply.getLogLastTerm()) {
+ } else if (followerLastLogIndex < 0 || followersLastLogTermInLeadersLog >= 0
+ && followersLastLogTermInLeadersLog == 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);
+
+ log.info("{}: follower {} appears to be behind the leader from the last snapshot - "
+ + "updated: matchIndex: {}, nextIndex: {}", logName(), followerId,
+ appendEntriesReply.getLogLastTerm(), followerLogInformation.getMatchIndex(),
+ followerLogInformation.getNextIndex());
} 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.
- followerLogInformation.decrNextIndex();
- updated = true;
+ if (followerLogInformation.decrNextIndex()) {
+ updated = true;
- LOG.debug("{}: follower's last log term {} conflicts with the leader's {} - dec next index to {}",
- logName(), appendEntriesReply.getLogLastTerm(), followersLastLogTermInLeadersLog,
- followerLogInformation.getNextIndex());
+ log.info("{}: follower {} last log term {} conflicts with the leader's {} - dec next index to {}",
+ logName(), followerId, appendEntriesReply.getLogLastTerm(),
+ followersLastLogTermInLeadersLog, followerLogInformation.getNextIndex());
+ }
}
}
- // 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: {}",
+ 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;
+ possiblyUpdateCommitIndex();
- LOG.trace("{}: checking Nth index {}", logName(), N);
+ //Send the next log entry immediately, if possible, no need to wait for heartbeat to trigger that event
+ sendUpdatesToFollower(followerId, followerLogInformation, false, !updated);
+
+ return this;
+ }
+
+ private void possiblyUpdateCommitIndex() {
+ // Figure out if we can update the the commitIndex as follows:
+ // If there exists an index N such that N > commitIndex, a majority of matchIndex[i] ⥠N,
+ // and log[N].term == currentTerm:
+ // set commitIndex = N (§5.3, §5.4).
+ for (long index = context.getCommitIndex() + 1; ; index++) {
+ ReplicatedLogEntry replicatedLogEntry = context.getReplicatedLog().get(index);
+ if (replicatedLogEntry == null) {
+ log.trace("{}: ReplicatedLogEntry not found for index {} - snapshotIndex: {}, journal size: {}",
+ logName(), index, context.getReplicatedLog().getSnapshotIndex(),
+ context.getReplicatedLog().size());
+ break;
+ }
+
+ // Count our entry if it has been persisted.
+ int replicatedCount = replicatedLogEntry.isPersistencePending() ? 0 : 1;
+
+ if (replicatedCount == 0) {
+ // We don't commit and apply a log entry until we've gotten the ack from our local persistence,
+ // even though there *shouldn't* be any issue with updating the commit index if we get a consensus
+ // amongst the followers w/o the local persistence ack.
+ break;
+ }
+
+ log.trace("{}: checking Nth index {}", logName(), index);
for (FollowerLogInformation info : followerToLog.values()) {
final PeerInfo peerInfo = context.getPeerInfo(info.getId());
- if(info.getMatchIndex() >= N && peerInfo != null && peerInfo.isVoting()) {
+ if (info.getMatchIndex() >= index && peerInfo != null && peerInfo.isVoting()) {
replicatedCount++;
- } else if(LOG.isTraceEnabled()) {
- LOG.trace("{}: Not counting follower {} - matchIndex: {}, {}", logName(), info.getId(),
+ } 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 (log.isTraceEnabled()) {
+ log.trace("{}: replicatedCount {}, minReplicationCount: {}", logName(), replicatedCount,
+ minReplicationCount);
}
if (replicatedCount >= minReplicationCount) {
- ReplicatedLogEntry replicatedLogEntry = context.getReplicatedLog().get(N);
- 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);
+ log.trace("{}: Setting commit index to {}", logName(), index);
+ context.setCommitIndex(index);
} 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());
+ log.debug("{}: Not updating commit index to {} - retrieved log entry with index {}, "
+ + "term {} does not match the current term {}", logName(), index,
+ replicatedLogEntry.getIndex(), replicatedLogEntry.getTerm(), currentTerm());
}
} else {
- LOG.trace("{}: minReplicationCount not reached, actual {} - breaking", logName(), replicatedCount);
+ 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());
- }
+ log.debug("{}: Applying to log - commitIndex: {}, lastAppliedIndex: {}", logName(),
+ context.getCommitIndex(), context.getLastApplied());
applyLogToStateMachine(context.getCommitIndex());
}
@@ -360,11 +382,6 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
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, !updated);
-
- return this;
}
private boolean updateFollowerLogInformation(FollowerLogInformation followerLogInformation,
@@ -372,10 +389,11 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
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());
+ if (updated && log.isDebugEnabled()) {
+ log.debug(
+ "{}: handleAppendEntriesReply - FollowerLogInformation for {} updated: matchIndex: {}, nextIndex: {}",
+ logName(), followerLogInformation.getId(), followerLogInformation.getMatchIndex(),
+ followerLogInformation.getNextIndex());
}
return updated;
}
@@ -425,7 +443,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
// 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 {} - switching to Follower",
+ log.info("{}: 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);
@@ -438,14 +456,16 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
beforeSendHeartbeat();
sendHeartBeat();
scheduleHeartBeat(context.getConfigParams().getHeartBeatInterval());
- } else if(message instanceof SendInstallSnapshot) {
- // received from RaftActor
- setSnapshot(((SendInstallSnapshot) message).getSnapshot());
+ } else if (message instanceof SendInstallSnapshot) {
+ SendInstallSnapshot sendInstallSnapshot = (SendInstallSnapshot) message;
+ setSnapshot(new SnapshotHolder(sendInstallSnapshot.getSnapshot(), sendInstallSnapshot.getSnapshotBytes()));
sendInstallSnapshot();
} else if (message instanceof Replicate) {
replicate((Replicate) message);
} else if (message instanceof InstallSnapshotReply) {
handleInstallSnapshotReply((InstallSnapshotReply) message);
+ } else if (message instanceof CheckConsensusReached) {
+ possiblyUpdateCommitIndex();
} else {
return super.handleMessage(sender, message);
}
@@ -454,20 +474,20 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
}
private void handleInstallSnapshotReply(InstallSnapshotReply reply) {
- LOG.debug("{}: handleInstallSnapshotReply: {}", logName(), reply);
+ log.debug("{}: handleInstallSnapshotReply: {}", logName(), reply);
String followerId = reply.getFollowerId();
FollowerLogInformation followerLogInformation = followerToLog.get(followerId);
- if(followerLogInformation == null) {
+ if (followerLogInformation == null) {
// This can happen during AddServer if it times out.
- LOG.error("{}: FollowerLogInformation not found for follower {} in InstallSnapshotReply",
+ log.error("{}: FollowerLogInformation not found for follower {} in InstallSnapshotReply",
logName(), followerId);
return;
}
LeaderInstallSnapshotState installSnapshotState = followerLogInformation.getInstallSnapshotState();
if (installSnapshotState == null) {
- LOG.error("{}: LeaderInstallSnapshotState not found for follower {} in InstallSnapshotReply",
+ log.error("{}: LeaderInstallSnapshotState not found for follower {} in InstallSnapshotReply",
logName(), followerId);
return;
}
@@ -477,24 +497,17 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
if (installSnapshotState.getChunkIndex() == reply.getChunkIndex()) {
boolean wasLastChunk = false;
if (reply.isSuccess()) {
- if(installSnapshotState.isLastChunk(reply.getChunkIndex())) {
+ if (installSnapshotState.isLastChunk(reply.getChunkIndex())) {
//this was the last chunk reply
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: InstallSnapshotReply received, " +
- "last chunk received, Chunk: {}. Follower: {} Setting nextIndex: {}",
- logName(), reply.getChunkIndex(), followerId,
- context.getReplicatedLog().getSnapshotIndex() + 1
- );
- }
- long followerMatchIndex = snapshot.get().getLastIncludedIndex();
+ long followerMatchIndex = snapshotHolder.get().getLastIncludedIndex();
followerLogInformation.setMatchIndex(followerMatchIndex);
followerLogInformation.setNextIndex(followerMatchIndex + 1);
followerLogInformation.clearLeaderInstallSnapshotState();
- LOG.debug("{}: follower: {}, matchIndex set to {}, nextIndex set to {}",
- logName(), followerId, followerLogInformation.getMatchIndex(),
- followerLogInformation.getNextIndex());
+ log.info("{}: Snapshot successfully installed on follower {} (last chunk {}) - "
+ + "matchIndex set to {}, nextIndex set to {}", logName(), followerId, reply.getChunkIndex(),
+ followerLogInformation.getMatchIndex(), followerLogInformation.getNextIndex());
if (!anyFollowersInstallingSnapshot()) {
// once there are no pending followers receiving snapshots
@@ -503,18 +516,17 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
}
wasLastChunk = true;
- if(context.getPeerInfo(followerId).getVotingState() == VotingState.VOTING_NOT_INITIALIZED){
+ 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");
+ log.debug("Sent message UnInitializedFollowerSnapshotReply to self");
}
} else {
installSnapshotState.markSendStatus(true);
}
} else {
- LOG.info("{}: InstallSnapshotReply received sending snapshot chunk failed, Will retry, Chunk: {}",
- logName(), reply.getChunkIndex());
+ log.warn("{}: Received failed InstallSnapshotReply - will retry: {}", logName(), reply);
installSnapshotState.markSendStatus(false);
}
@@ -524,17 +536,17 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
purgeInMemoryLog();
} else if (!wasLastChunk && installSnapshotState.canSendNextChunk()) {
ActorSelection followerActor = context.getPeerActorSelection(followerId);
- if(followerActor != null) {
+ if (followerActor != null) {
sendSnapshotChunk(followerActor, followerLogInformation);
}
}
} else {
- LOG.error("{}: Chunk index {} in InstallSnapshotReply from follower {} does not match expected index {}",
+ log.error("{}: Chunk index {} in InstallSnapshotReply from follower {} does not match expected index {}",
logName(), reply.getChunkIndex(), followerId,
installSnapshotState.getChunkIndex());
- if(reply.getChunkIndex() == LeaderInstallSnapshotState.INVALID_CHUNK_INDEX){
+ if (reply.getChunkIndex() == LeaderInstallSnapshotState.INVALID_CHUNK_INDEX) {
// Since the Follower did not find this index to be valid we should reset the follower snapshot
// so that Installing the snapshot can resume from the beginning
installSnapshotState.reset();
@@ -543,8 +555,8 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
}
private boolean anyFollowersInstallingSnapshot() {
- for(FollowerLogInformation info: followerToLog.values()) {
- if(info.getInstallSnapshotState() != null) {
+ for (FollowerLogInformation info: followerToLog.values()) {
+ if (info.getInstallSnapshotState() != null) {
return true;
}
@@ -556,12 +568,13 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
private void replicate(Replicate replicate) {
long logIndex = replicate.getReplicatedLogEntry().getIndex();
- LOG.debug("{}: Replicate message: identifier: {}, logIndex: {}, payload: {}", logName(),
- replicate.getIdentifier(), logIndex, replicate.getReplicatedLogEntry().getData().getClass());
+ log.debug("{}: Replicate message: identifier: {}, logIndex: {}, payload: {}, isSendImmediate: {}", logName(),
+ replicate.getIdentifier(), logIndex, replicate.getReplicatedLogEntry().getData().getClass(),
+ replicate.isSendImmediate());
// Create a tracker entry we will use this later to notify the
// client actor
- if(replicate.getClientActor() != null) {
+ if (replicate.getClientActor() != null) {
trackers.add(new ClientRequestTrackerImpl(replicate.getClientActor(), replicate.getIdentifier(),
logIndex));
}
@@ -569,12 +582,12 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
boolean applyModificationToState = !context.anyVotingPeers()
|| context.getRaftPolicy().applyModificationToStateBeforeConsensus();
- if(applyModificationToState){
+ if (applyModificationToState) {
context.setCommitIndex(logIndex);
applyLogToStateMachine(logIndex);
}
- if (!followerToLog.isEmpty()) {
+ if (replicate.isSendImmediate() && !followerToLog.isEmpty()) {
sendAppendEntries(0, false);
}
}
@@ -585,20 +598,17 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
final String followerId = e.getKey();
final FollowerLogInformation followerLogInformation = e.getValue();
// This checks helps not to send a repeat message to the follower
- if(!followerLogInformation.isFollowerActive() ||
- followerLogInformation.timeSinceLastActivity() >= timeSinceLastActivityInterval) {
+ if (!followerLogInformation.isFollowerActive()
+ || followerLogInformation.timeSinceLastActivity() >= timeSinceLastActivityInterval) {
sendUpdatesToFollower(followerId, followerLogInformation, true, isHeartbeat);
}
}
}
/**
- *
* This method checks if any update needs to be sent to the given follower. This includes append log entries,
* sending next snapshot chunk, and initiating a snapshot.
- * @return true if any update is sent, false otherwise
*/
-
private void sendUpdatesToFollower(String followerId, FollowerLogInformation followerLogInformation,
boolean sendHeartbeat, boolean isHeartbeat) {
@@ -614,7 +624,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
// if install snapshot is in process , then sent next chunk if possible
if (isFollowerActive && installSnapshotState.canSendNextChunk()) {
sendSnapshotChunk(followerActor, followerLogInformation);
- } else if(sendHeartbeat) {
+ } else if (sendHeartbeat) {
// we send a heartbeat even if we have not received a reply for the last chunk
sendAppendEntries = true;
}
@@ -622,17 +632,18 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
long leaderLastIndex = context.getReplicatedLog().lastIndex();
long leaderSnapShotIndex = context.getReplicatedLog().getSnapshotIndex();
- if((!isHeartbeat && LOG.isDebugEnabled()) || LOG.isTraceEnabled()) {
- LOG.debug("{}: Checking sendAppendEntries for follower {}: active: {}, followerNextIndex: {}, leaderLastIndex: {}, leaderSnapShotIndex: {}",
- logName(), followerId, isFollowerActive, followerNextIndex, leaderLastIndex, leaderSnapShotIndex);
+ 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(),
+ log.debug("{}: sendAppendEntries: {} is present for follower {}", logName(),
followerNextIndex, followerId);
- if(followerLogInformation.okToReplicate()) {
+ 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();
@@ -640,26 +651,31 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
context.getConfigParams().getSnapshotChunkSize());
sendAppendEntries = true;
}
- } else if (isFollowerActive && followerNextIndex >= 0 &&
- leaderLastIndex > followerNextIndex && !context.getSnapshotManager().isCapturing()) {
+ } else if (isFollowerActive && followerNextIndex >= 0
+ && 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(String.format("%s: InitiateInstallSnapshot to follower: %s, " +
- "follower-nextIndex: %d, leader-snapshot-index: %d, " +
- "leader-last-index: %d", logName(), followerId,
- followerNextIndex, leaderSnapShotIndex, leaderLastIndex));
- }
-
// Send heartbeat to follower whenever install snapshot is initiated.
sendAppendEntries = true;
if (canInstallSnapshot(followerNextIndex)) {
+ log.info("{}: Initiating install snapshot to follower {}: follower nextIndex: {}, leader "
+ + "snapshotIndex: {}, leader lastIndex: {}, leader log size: {}", logName(), followerId,
+ followerNextIndex, leaderSnapShotIndex, leaderLastIndex,
+ context.getReplicatedLog().size());
+
initiateCaptureSnapshot(followerId);
+ } else {
+ // It doesn't seem like we should ever reach here - most likely indicates sonething is
+ // wrong.
+ log.info("{}: Follower {} is behind but cannot install snapshot: follower nextIndex: {}, "
+ + "leader snapshotIndex: {}, leader lastIndex: {}, leader log size: {}", logName(),
+ followerId, followerNextIndex, leaderSnapShotIndex, leaderLastIndex,
+ context.getReplicatedLog().size());
}
- } else if(sendHeartbeat) {
+ } else if (sendHeartbeat) {
// we send an AppendEntries, even if the follower is inactive
// in-order to update the followers timestamp, in case it becomes active again
sendAppendEntries = true;
@@ -667,7 +683,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
}
- if(sendAppendEntries) {
+ if (sendAppendEntries) {
sendAppendEntriesToFollower(followerActor, entries, followerLogInformation);
}
}
@@ -692,8 +708,8 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
getLogEntryTerm(followerNextIndex - 1), entries,
leaderCommitIndex, super.getReplicatedToAllIndex(), context.getPayloadVersion());
- if(!entries.isEmpty() || LOG.isTraceEnabled()) {
- LOG.debug("{}: Sending AppendEntries to follower {}: {}", logName(), followerLogInformation.getId(),
+ if (!entries.isEmpty() || log.isTraceEnabled()) {
+ log.debug("{}: Sending AppendEntries to follower {}: {}", logName(), followerLogInformation.getId(),
appendEntries);
}
@@ -703,6 +719,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
/**
* Initiates a snapshot capture to install on a follower.
*
+ *
* Install Snapshot works as follows
* 1. Leader initiates the capture snapshot by calling createSnapshot on the RaftActor.
* 2. On receipt of the CaptureSnapshotReply message, the RaftActor persists the snapshot and makes a call to
@@ -720,7 +737,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
*/
public boolean initiateCaptureSnapshot(String followerId) {
FollowerLogInformation followerLogInfo = followerToLog.get(followerId);
- if (snapshot.isPresent()) {
+ if (snapshotHolder.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);
@@ -728,31 +745,30 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
// Note: sendSnapshotChunk will set the LeaderInstallSnapshotState.
sendSnapshotChunk(followerActor, followerLogInfo);
return true;
- } else {
- boolean captureInitiated = context.getSnapshotManager().captureToInstall(context.getReplicatedLog().last(),
- this.getReplicatedToAllIndex(), followerId);
- if(captureInitiated) {
- followerLogInfo.setLeaderInstallSnapshotState(new LeaderInstallSnapshotState(
- context.getConfigParams().getSnapshotChunkSize(), logName()));
- }
+ }
- return captureInitiated;
+ boolean captureInitiated = context.getSnapshotManager().captureToInstall(context.getReplicatedLog().last(),
+ this.getReplicatedToAllIndex(), followerId);
+ if (captureInitiated) {
+ followerLogInfo.setLeaderInstallSnapshotState(new LeaderInstallSnapshotState(
+ context.getConfigParams().getSnapshotChunkSize(), logName()));
}
+
+ return captureInitiated;
}
- private boolean canInstallSnapshot(long nextIndex){
+ 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));
+ return nextIndex == -1 || !context.getReplicatedLog().isPresent(nextIndex)
+ && context.getReplicatedLog().isInSnapshot(nextIndex);
}
private void sendInstallSnapshot() {
- LOG.debug("{}: sendInstallSnapshot", logName());
+ log.debug("{}: sendInstallSnapshot", logName());
for (Entry e : followerToLog.entrySet()) {
String followerId = e.getKey();
ActorSelection followerActor = context.getPeerActorSelection(followerId);
@@ -760,9 +776,9 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
if (followerActor != null) {
long nextIndex = followerLogInfo.getNextIndex();
- if (followerLogInfo.getInstallSnapshotState() != null ||
- context.getPeerInfo(followerId).getVotingState() == VotingState.VOTING_NOT_INITIALIZED ||
- canInstallSnapshot(nextIndex)) {
+ if (followerLogInfo.getInstallSnapshotState() != null
+ || context.getPeerInfo(followerId).getVotingState() == VotingState.VOTING_NOT_INITIALIZED
+ || canInstallSnapshot(nextIndex)) {
sendSnapshotChunk(followerActor, followerLogInfo);
}
}
@@ -774,7 +790,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
* InstallSnapshot should qualify as a heartbeat too.
*/
private void sendSnapshotChunk(ActorSelection followerActor, FollowerLogInformation followerLogInfo) {
- if (snapshot.isPresent()) {
+ if (snapshotHolder.isPresent()) {
LeaderInstallSnapshotState installSnapshotState = followerLogInfo.getInstallSnapshotState();
if (installSnapshotState == null) {
installSnapshotState = new LeaderInstallSnapshotState(context.getConfigParams().getSnapshotChunkSize(),
@@ -782,44 +798,45 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
followerLogInfo.setLeaderInstallSnapshotState(installSnapshotState);
}
- // Ensure the snapshot bytes are set - this is a no-op.
- installSnapshotState.setSnapshotBytes(snapshot.get().getSnapshotBytes());
+ try {
+ // Ensure the snapshot bytes are set - this is a no-op.
+ installSnapshotState.setSnapshotBytes(snapshotHolder.get().getSnapshotBytes());
- byte[] nextSnapshotChunk = installSnapshotState.getNextChunk();
+ byte[] nextSnapshotChunk = installSnapshotState.getNextChunk();
- LOG.debug("{}: next snapshot chunk size for follower {}: {}", logName(), followerLogInfo.getId(),
- nextSnapshotChunk.length);
+ log.debug("{}: next snapshot chunk size for follower {}: {}", logName(), followerLogInfo.getId(),
+ nextSnapshotChunk.length);
- int nextChunkIndex = installSnapshotState.incrementChunkIndex();
- Optional serverConfig = Optional.absent();
- if(installSnapshotState.isLastChunk(nextChunkIndex)) {
- serverConfig = Optional.fromNullable(context.getPeerServerInfo(true));
- }
+ int nextChunkIndex = installSnapshotState.incrementChunkIndex();
+ Optional serverConfig = Optional.absent();
+ if (installSnapshotState.isLastChunk(nextChunkIndex)) {
+ serverConfig = Optional.fromNullable(context.getPeerServerInfo(true));
+ }
- followerActor.tell(
- new InstallSnapshot(currentTerm(), context.getId(),
- snapshot.get().getLastIncludedIndex(),
- snapshot.get().getLastIncludedTerm(),
- nextSnapshotChunk,
- nextChunkIndex,
- installSnapshotState.getTotalChunks(),
- Optional.of(installSnapshotState.getLastChunkHashCode()),
- serverConfig
- ).toSerializable(followerLogInfo.getRaftVersion()),
- actor()
- );
-
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: InstallSnapshot sent to follower {}, Chunk: {}/{}",
- logName(), followerActor.path(), installSnapshotState.getChunkIndex(),
- installSnapshotState.getTotalChunks());
+ followerActor.tell(
+ new InstallSnapshot(currentTerm(), context.getId(),
+ snapshotHolder.get().getLastIncludedIndex(),
+ snapshotHolder.get().getLastIncludedTerm(),
+ nextSnapshotChunk,
+ nextChunkIndex,
+ installSnapshotState.getTotalChunks(),
+ Optional.of(installSnapshotState.getLastChunkHashCode()),
+ serverConfig
+ ).toSerializable(followerLogInfo.getRaftVersion()),
+ actor()
+ );
+
+ log.debug("{}: InstallSnapshot sent to follower {}, Chunk: {}/{}", logName(), followerActor.path(),
+ installSnapshotState.getChunkIndex(), installSnapshotState.getTotalChunks());
+ } catch (IOException e) {
+ throw Throwables.propagate(e);
}
}
}
private void sendHeartBeat() {
if (!followerToLog.isEmpty()) {
- LOG.trace("{}: Sending heartbeat", logName());
+ log.trace("{}: Sending heartbeat", logName());
sendAppendEntries(context.getConfigParams().getHeartBeatInterval().toMillis(), true);
}
}
@@ -868,7 +885,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
int minPresent = getMinIsolatedLeaderPeerCount();
for (FollowerLogInformation followerLogInformation : followerToLog.values()) {
final PeerInfo peerInfo = context.getPeerInfo(followerLogInformation.getId());
- if(peerInfo != null && peerInfo.isVoting() && followerLogInformation.isFollowerActive()) {
+ if (peerInfo != null && peerInfo.isVoting() && followerLogInformation.isFollowerActive()) {
--minPresent;
if (minPresent == 0) {
return false;
@@ -905,15 +922,15 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
return followerToLog.size();
}
- private static class SnapshotHolder {
+ static class SnapshotHolder {
private final long lastIncludedTerm;
private final long lastIncludedIndex;
- private final ByteString snapshotBytes;
+ private final ByteSource snapshotBytes;
- SnapshotHolder(Snapshot snapshot) {
+ SnapshotHolder(Snapshot snapshot, ByteSource snapshotBytes) {
this.lastIncludedTerm = snapshot.getLastAppliedTerm();
this.lastIncludedIndex = snapshot.getLastAppliedIndex();
- this.snapshotBytes = ByteString.copyFrom(snapshot.getState());
+ this.snapshotBytes = snapshotBytes;
}
long getLastIncludedTerm() {
@@ -924,7 +941,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
return lastIncludedIndex;
}
- ByteString getSnapshotBytes() {
+ ByteSource getSnapshotBytes() {
return snapshotBytes;
}
}