package org.opendaylight.controller.cluster.raft.behaviors;
import akka.actor.ActorRef;
+import akka.actor.ActorSelection;
+import akka.actor.Address;
+import akka.cluster.Cluster;
+import akka.cluster.ClusterEvent.CurrentClusterState;
+import akka.cluster.Member;
+import akka.cluster.MemberStatus;
+import akka.japi.Procedure;
import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Stopwatch;
+import java.io.IOException;
import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import javax.annotation.Nullable;
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.ServerConfigurationPayload;
-import org.opendaylight.controller.cluster.raft.Snapshot;
import org.opendaylight.controller.cluster.raft.base.messages.ApplySnapshot;
import org.opendaylight.controller.cluster.raft.base.messages.ElectionTimeout;
+import org.opendaylight.controller.cluster.raft.base.messages.TimeoutNow;
import org.opendaylight.controller.cluster.raft.messages.AppendEntries;
import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
import org.opendaylight.controller.cluster.raft.messages.InstallSnapshot;
import org.opendaylight.controller.cluster.raft.messages.RaftRPC;
import org.opendaylight.controller.cluster.raft.messages.RequestVote;
import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply;
+import org.opendaylight.controller.cluster.raft.persisted.ServerConfigurationPayload;
+import org.opendaylight.controller.cluster.raft.persisted.Snapshot;
/**
- * The behavior of a RaftActor in the Follower state
- * <p/>
+ * The behavior of a RaftActor in the Follower raft state.
* <ul>
* <li> Respond to RPCs from candidates and leaders
* <li> If election timeout elapses without receiving AppendEntries
* </ul>
*/
public class Follower extends AbstractRaftActorBehavior {
-
- private SnapshotTracker snapshotTracker = null;
+ private static final long MAX_ELECTION_TIMEOUT_FACTOR = 18;
private final SyncStatusTracker initialSyncStatusTracker;
- private static final int SYNC_THRESHOLD = 10;
+ private final Stopwatch lastLeaderMessageTimer = Stopwatch.createStarted();
+ private SnapshotTracker snapshotTracker = null;
+ private String leaderId;
+ private short leaderPayloadVersion;
- public Follower(RaftActorContext context) {
- this(context, null);
+ public Follower(final RaftActorContext context) {
+ this(context, null, (short)-1);
}
- public Follower(RaftActorContext context, String initialLeaderId) {
+ public Follower(final RaftActorContext context, final String initialLeaderId,
+ final short initialLeaderPayloadVersion) {
super(context, RaftState.Follower);
- leaderId = initialLeaderId;
+ this.leaderId = initialLeaderId;
+ this.leaderPayloadVersion = initialLeaderPayloadVersion;
- initialSyncStatusTracker = new SyncStatusTracker(context.getActor(), getId(), SYNC_THRESHOLD);
+ initialSyncStatusTracker = new SyncStatusTracker(context.getActor(), getId(), context.getConfigParams()
+ .getSyncIndexThreshold());
- if(canStartElection()) {
- if (context.getPeerIds().isEmpty() && getLeaderId() == null) {
- actor().tell(ELECTION_TIMEOUT, actor());
- } else {
- scheduleElection(electionDuration());
- }
+ if (context.getPeerIds().isEmpty() && getLeaderId() == null) {
+ actor().tell(TimeoutNow.INSTANCE, actor());
+ } else {
+ scheduleElection(electionDuration());
}
-
}
- private boolean isLogEntryPresent(long index){
- if(index == context.getReplicatedLog().getSnapshotIndex()){
- return true;
- }
+ @Override
+ public final String getLeaderId() {
+ return leaderId;
+ }
- ReplicatedLogEntry previousEntry = context.getReplicatedLog()
- .get(index);
+ @VisibleForTesting
+ protected final void setLeaderId(@Nullable final String leaderId) {
+ this.leaderId = leaderId;
+ }
- return previousEntry != null;
+ @Override
+ public short getLeaderPayloadVersion() {
+ return leaderPayloadVersion;
+ }
+ @VisibleForTesting
+ protected final void setLeaderPayloadVersion(final short leaderPayloadVersion) {
+ this.leaderPayloadVersion = leaderPayloadVersion;
}
- private long getLogEntryTerm(long index){
- if(index == context.getReplicatedLog().getSnapshotIndex()){
- return context.getReplicatedLog().getSnapshotTerm();
+ private void restartLastLeaderMessageTimer() {
+ if (lastLeaderMessageTimer.isRunning()) {
+ lastLeaderMessageTimer.reset();
}
- ReplicatedLogEntry previousEntry = context.getReplicatedLog()
- .get(index);
+ lastLeaderMessageTimer.start();
+ }
- if(previousEntry != null){
- return previousEntry.getTerm();
+ private boolean isLogEntryPresent(final long index) {
+ if (context.getReplicatedLog().isInSnapshot(index)) {
+ return true;
}
- return -1;
+ ReplicatedLogEntry entry = context.getReplicatedLog().get(index);
+ return entry != null;
+
}
- private void updateInitialSyncStatus(long currentLeaderCommit, String leaderId){
- initialSyncStatusTracker.update(leaderId, currentLeaderCommit, context.getCommitIndex());
+ private void updateInitialSyncStatus(final long currentLeaderCommit, final String newLeaderId) {
+ initialSyncStatusTracker.update(newLeaderId, currentLeaderCommit, context.getCommitIndex());
}
- @Override protected RaftActorBehavior handleAppendEntries(ActorRef sender,
- AppendEntries appendEntries) {
+ @Override
+ protected RaftActorBehavior handleAppendEntries(final ActorRef sender, final AppendEntries appendEntries) {
int numLogEntries = appendEntries.getEntries() != null ? appendEntries.getEntries().size() : 0;
- if(LOG.isTraceEnabled()) {
- LOG.trace("{}: handleAppendEntries: {}", logName(), appendEntries);
- } else if(LOG.isDebugEnabled() && numLogEntries > 0) {
- LOG.debug("{}: handleAppendEntries: {}", logName(), appendEntries);
+ if (log.isTraceEnabled()) {
+ log.trace("{}: handleAppendEntries: {}", logName(), appendEntries);
+ } else if (log.isDebugEnabled() && numLogEntries > 0) {
+ log.debug("{}: handleAppendEntries: {}", logName(), appendEntries);
}
// TODO : Refactor this method into a bunch of smaller methods
// to make it easier to read. Before refactoring ensure tests
// cover the code properly
+ if (snapshotTracker != null && !snapshotTracker.getLeaderId().equals(appendEntries.getLeaderId())) {
+ log.debug("{}: snapshot install is in progress but the prior snapshot leaderId {} does not match the "
+ + "AppendEntries leaderId {}", logName(), snapshotTracker.getLeaderId(), appendEntries.getLeaderId());
+ closeSnapshotTracker();
+ }
+
if (snapshotTracker != null || context.getSnapshotManager().isApplying()) {
// if snapshot install is in progress, follower should just acknowledge append entries with a reply.
AppendEntriesReply reply = new AppendEntriesReply(context.getId(), currentTerm(), true,
lastIndex(), lastTerm(), context.getPayloadVersion());
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: snapshot install is in progress, replying immediately with {}", logName(), reply);
- }
+ log.debug("{}: snapshot install is in progress, replying immediately with {}", logName(), reply);
sender.tell(reply, actor());
return this;
// If we got here then we do appear to be talking to the leader
leaderId = appendEntries.getLeaderId();
+ leaderPayloadVersion = appendEntries.getPayloadVersion();
- setLeaderPayloadVersion(appendEntries.getPayloadVersion());
-
- updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId());
// First check if the logs are in sync or not
long lastIndex = lastIndex();
// We found that the log was out of sync so just send a negative
// reply and return
- LOG.debug("{}: Follower is out-of-sync, so sending negative reply, lastIndex: {}, lastTerm: {}",
- logName(), lastIndex, lastTerm());
+ final AppendEntriesReply reply = new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex,
+ lastTerm(), context.getPayloadVersion());
- sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex,
- lastTerm(), context.getPayloadVersion()), actor());
+ log.info("{}: Follower is out-of-sync so sending negative reply: {}", logName(), reply);
+ updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId());
+ sender.tell(reply, actor());
return this;
}
if (appendEntries.getEntries() != null && appendEntries.getEntries().size() > 0) {
- LOG.debug("{}: Number of entries to be appended = {}", logName(),
+ log.debug("{}: Number of entries to be appended = {}", logName(),
appendEntries.getEntries().size());
// 3. If an existing entry conflicts with a new one (same index
// Find the entry up until the one that is not in the follower's log
for (int i = 0;i < appendEntries.getEntries().size(); i++, addEntriesFrom++) {
ReplicatedLogEntry matchEntry = appendEntries.getEntries().get(i);
- ReplicatedLogEntry newEntry = context.getReplicatedLog().get(matchEntry.getIndex());
- if (newEntry == null) {
- //newEntry not found in the log
+ if (!isLogEntryPresent(matchEntry.getIndex())) {
+ // newEntry not found in the log
break;
}
- if (newEntry.getTerm() == matchEntry.getTerm()) {
+ long existingEntryTerm = getLogEntryTerm(matchEntry.getIndex());
+
+ log.debug("{}: matchEntry {} is present: existingEntryTerm: {}", logName(), matchEntry,
+ existingEntryTerm);
+
+ // existingEntryTerm == -1 means it's in the snapshot and not in the log. We don't know
+ // what the term was so we'll assume it matches.
+ if (existingEntryTerm == -1 || existingEntryTerm == matchEntry.getTerm()) {
continue;
}
- if(!context.getRaftPolicy().applyModificationToStateBeforeConsensus()) {
+ if (!context.getRaftPolicy().applyModificationToStateBeforeConsensus()) {
- LOG.debug("{}: Removing entries from log starting at {}", logName(),
- matchEntry.getIndex());
+ log.info("{}: Removing entries from log starting at {}", logName(), matchEntry.getIndex());
// Entries do not match so remove all subsequent entries
- context.getReplicatedLog().removeFromAndPersist(matchEntry.getIndex());
+ if (!context.getReplicatedLog().removeFromAndPersist(matchEntry.getIndex())) {
+ // Could not remove the entries - this means the matchEntry index must be in the
+ // snapshot and not the log. In this case the prior entries are part of the state
+ // so we must send back a reply to force a snapshot to completely re-sync the
+ // follower's log and state.
+
+ log.info("{}: Could not remove entries - sending reply to force snapshot", logName());
+ updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId());
+ sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex,
+ lastTerm(), context.getPayloadVersion(), true), actor());
+ return this;
+ }
+
break;
} else {
+ updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId());
sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex,
lastTerm(), context.getPayloadVersion(), true), actor());
return this;
}
lastIndex = lastIndex();
- LOG.debug("{}: After cleanup entries to be added from = {}", logName(),
- (addEntriesFrom + lastIndex));
+ log.debug("{}: After cleanup, lastIndex: {}, entries to be added from: {}", logName(),
+ lastIndex, addEntriesFrom);
+
+ // When persistence successfully completes for each new log entry appended, we need to determine if we
+ // should capture a snapshot to compact the persisted log. shouldCaptureSnapshot tracks whether or not
+ // one of the log entries has exceeded the log size threshold whereby a snapshot should be taken. However
+ // we don't initiate the snapshot at that log entry but rather after the last log entry has been persisted.
+ // This is done because subsequent log entries after the one that tripped the threshold may have been
+ // applied to the state already, as the persistence callback occurs async, and we want those entries
+ // purged from the persisted log as well.
+ final AtomicBoolean shouldCaptureSnapshot = new AtomicBoolean(false);
+ final Procedure<ReplicatedLogEntry> appendAndPersistCallback = logEntry -> {
+ final ReplicatedLogEntry lastEntryToAppend = appendEntries.getEntries().get(
+ appendEntries.getEntries().size() - 1);
+ if (shouldCaptureSnapshot.get() && logEntry == lastEntryToAppend) {
+ context.getSnapshotManager().capture(context.getReplicatedLog().last(), getReplicatedToAllIndex());
+ }
+ };
// 4. Append any new entries not already in the log
for (int i = addEntriesFrom; i < appendEntries.getEntries().size(); i++) {
ReplicatedLogEntry entry = appendEntries.getEntries().get(i);
- LOG.debug("{}: Append entry to log {}", logName(), entry.getData());
+ log.debug("{}: Append entry to log {}", logName(), entry.getData());
+
+ context.getReplicatedLog().appendAndPersist(entry, appendAndPersistCallback, false);
- context.getReplicatedLog().appendAndPersist(entry);
+ shouldCaptureSnapshot.compareAndSet(false,
+ context.getReplicatedLog().shouldCaptureSnapshot(entry.getIndex()));
- if(entry.getData() instanceof ServerConfigurationPayload) {
+ if (entry.getData() instanceof ServerConfigurationPayload) {
context.updatePeerIds((ServerConfigurationPayload)entry.getData());
}
}
- LOG.debug("{}: Log size is now {}", logName(), context.getReplicatedLog().size());
+ log.debug("{}: Log size is now {}", logName(), context.getReplicatedLog().size());
}
// 5. If leaderCommit > commitIndex, set commitIndex =
lastIndex = lastIndex();
long prevCommitIndex = context.getCommitIndex();
- context.setCommitIndex(Math.min(appendEntries.getLeaderCommit(), lastIndex));
+ if (appendEntries.getLeaderCommit() > prevCommitIndex) {
+ context.setCommitIndex(Math.min(appendEntries.getLeaderCommit(), lastIndex));
+ }
if (prevCommitIndex != context.getCommitIndex()) {
- LOG.debug("{}: Commit index set to {}", logName(), context.getCommitIndex());
+ log.debug("{}: Commit index set to {}", logName(), context.getCommitIndex());
+ }
+
+ AppendEntriesReply reply = new AppendEntriesReply(context.getId(), currentTerm(), true,
+ lastIndex, lastTerm(), context.getPayloadVersion());
+
+ if (log.isTraceEnabled()) {
+ log.trace("{}: handleAppendEntries returning : {}", logName(), reply);
+ } else if (log.isDebugEnabled() && numLogEntries > 0) {
+ log.debug("{}: handleAppendEntries returning : {}", logName(), reply);
}
+ // Reply to the leader before applying any previous state so as not to hold up leader consensus.
+ updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId());
+ sender.tell(reply, actor());
+
// If commitIndex > lastApplied: increment lastApplied, apply
// log[lastApplied] to state machine (§5.3)
// check if there are any entries to be applied. last-applied can be equal to last-index
- if (appendEntries.getLeaderCommit() > context.getLastApplied() &&
- context.getLastApplied() < lastIndex) {
- if(LOG.isDebugEnabled()) {
- LOG.debug("{}: applyLogToStateMachine, " +
- "appendEntries.getLeaderCommit(): {}," +
- "context.getLastApplied(): {}, lastIndex(): {}", logName(),
+ if (appendEntries.getLeaderCommit() > context.getLastApplied()
+ && context.getLastApplied() < lastIndex) {
+ if (log.isDebugEnabled()) {
+ log.debug("{}: applyLogToStateMachine, appendEntries.getLeaderCommit(): {}, "
+ + "context.getLastApplied(): {}, lastIndex(): {}", logName(),
appendEntries.getLeaderCommit(), context.getLastApplied(), lastIndex);
}
applyLogToStateMachine(appendEntries.getLeaderCommit());
}
- AppendEntriesReply reply = new AppendEntriesReply(context.getId(), currentTerm(), true,
- lastIndex, lastTerm(), context.getPayloadVersion());
-
- if(LOG.isTraceEnabled()) {
- LOG.trace("{}: handleAppendEntries returning : {}", logName(), reply);
- } else if(LOG.isDebugEnabled() && numLogEntries > 0) {
- LOG.debug("{}: handleAppendEntries returning : {}", logName(), reply);
- }
-
- sender.tell(reply, actor());
-
if (!context.getSnapshotManager().isCapturing()) {
super.performSnapshotWithoutCapture(appendEntries.getReplicatedToAllIndex());
}
return this;
}
- private boolean isOutOfSync(AppendEntries appendEntries) {
-
- long prevLogTerm = getLogEntryTerm(appendEntries.getPrevLogIndex());
- boolean prevEntryPresent = isLogEntryPresent(appendEntries.getPrevLogIndex());
- long lastIndex = lastIndex();
- int numLogEntries = appendEntries.getEntries() != null ? appendEntries.getEntries().size() : 0;
- boolean outOfSync = true;
+ private boolean isOutOfSync(final AppendEntries appendEntries) {
+ final long lastIndex = lastIndex();
if (lastIndex == -1 && appendEntries.getPrevLogIndex() != -1) {
- // The follower's log is out of sync because the leader does have
- // an entry at prevLogIndex and this follower has no entries in
- // it's log.
-
- LOG.debug("{}: The followers log is empty and the senders prevLogIndex is {}",
- logName(), appendEntries.getPrevLogIndex());
- } else if (lastIndex > -1 && appendEntries.getPrevLogIndex() != -1 && !prevEntryPresent) {
-
- // The follower's log is out of sync because the Leader's
- // prevLogIndex entry was not found in it's log
-
- LOG.debug("{}: The log is not empty but the prevLogIndex {} was not found in it",
- logName(), appendEntries.getPrevLogIndex());
- } else if (lastIndex > -1 && prevEntryPresent && prevLogTerm != appendEntries.getPrevLogTerm()) {
-
- // The follower's log is out of sync because the Leader's
- // prevLogIndex entry does exist in the follower's log but it has
- // a different term in it
-
- LOG.debug(
- "{}: Cannot append entries because previous entry term {} is not equal to append entries prevLogTerm {}",
- logName(), prevLogTerm, appendEntries.getPrevLogTerm());
- } else if(appendEntries.getPrevLogIndex() == -1 && appendEntries.getPrevLogTerm() == -1
- && appendEntries.getReplicatedToAllIndex() != -1
- && !isLogEntryPresent(appendEntries.getReplicatedToAllIndex())
- && !context.getReplicatedLog().isInSnapshot(appendEntries.getReplicatedToAllIndex())) {
- // This append entry comes from a leader who has it's log aggressively trimmed and so does not have
- // the previous entry in it's in-memory journal
-
- LOG.debug(
- "{}: Cannot append entries because the replicatedToAllIndex {} does not appear to be in the in-memory journal",
- logName(), appendEntries.getReplicatedToAllIndex());
- } else if(appendEntries.getPrevLogIndex() == -1 && appendEntries.getPrevLogTerm() == -1
- && appendEntries.getReplicatedToAllIndex() != -1 && numLogEntries > 0
- && !isLogEntryPresent(appendEntries.getEntries().get(0).getIndex() - 1)
- && !context.getReplicatedLog().isInSnapshot(appendEntries.getEntries().get(0).getIndex() - 1)) {
- LOG.debug(
- "{}: Cannot append entries because the calculated previousIndex {} was not found in the in-memory journal",
- logName(), appendEntries.getEntries().get(0).getIndex() - 1);
- } else {
- outOfSync = false;
+ // The follower's log is out of sync because the leader does have an entry at prevLogIndex and this
+ // follower has no entries in it's log.
+
+ log.info("{}: The followers log is empty and the senders prevLogIndex is {}", logName(),
+ appendEntries.getPrevLogIndex());
+ return true;
+ }
+
+ if (lastIndex > -1) {
+ if (isLogEntryPresent(appendEntries.getPrevLogIndex())) {
+ final long prevLogTerm = getLogEntryTerm(appendEntries.getPrevLogIndex());
+ if (prevLogTerm != appendEntries.getPrevLogTerm()) {
+
+ // The follower's log is out of sync because the Leader's prevLogIndex entry does exist
+ // in the follower's log but it has a different term in it
+
+ log.info("{}: The prevLogIndex {} was found in the log but the term {} is not equal to the append "
+ + "entries prevLogTerm {} - lastIndex: {}, snapshotIndex: {}", logName(),
+ appendEntries.getPrevLogIndex(), prevLogTerm, appendEntries.getPrevLogTerm(), lastIndex,
+ context.getReplicatedLog().getSnapshotIndex());
+ return true;
+ }
+ } else if (appendEntries.getPrevLogIndex() != -1) {
+
+ // The follower's log is out of sync because the Leader's prevLogIndex entry was not found in it's log
+
+ log.info("{}: The log is not empty but the prevLogIndex {} was not found in it - lastIndex: {}, "
+ + "snapshotIndex: {}", logName(), appendEntries.getPrevLogIndex(), lastIndex,
+ context.getReplicatedLog().getSnapshotIndex());
+ return true;
+ }
}
- return outOfSync;
+
+ if (appendEntries.getPrevLogIndex() == -1 && appendEntries.getPrevLogTerm() == -1
+ && appendEntries.getReplicatedToAllIndex() != -1) {
+ if (!isLogEntryPresent(appendEntries.getReplicatedToAllIndex())) {
+ // This append entry comes from a leader who has it's log aggressively trimmed and so does not have
+ // the previous entry in it's in-memory journal
+
+ log.info("{}: Cannot append entries because the replicatedToAllIndex {} does not appear to be in the "
+ + "in-memory journal", logName(), appendEntries.getReplicatedToAllIndex());
+ return true;
+ }
+
+ final List<ReplicatedLogEntry> entries = appendEntries.getEntries();
+ if (entries != null && entries.size() > 0 && !isLogEntryPresent(entries.get(0).getIndex() - 1)) {
+ log.info("{}: Cannot append entries because the calculated previousIndex {} was not found in the "
+ + "in-memory journal", logName(), entries.get(0).getIndex() - 1);
+ return true;
+ }
+ }
+
+ return false;
}
- @Override protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender,
- AppendEntriesReply appendEntriesReply) {
+ @Override
+ protected RaftActorBehavior handleAppendEntriesReply(final ActorRef sender,
+ final AppendEntriesReply appendEntriesReply) {
return this;
}
- @Override protected RaftActorBehavior handleRequestVoteReply(ActorRef sender,
- RequestVoteReply requestVoteReply) {
+ @Override
+ protected RaftActorBehavior handleRequestVoteReply(final ActorRef sender,
+ final RequestVoteReply requestVoteReply) {
return this;
}
- @Override public RaftActorBehavior handleMessage(ActorRef sender, Object originalMessage) {
+ @Override
+ public RaftActorBehavior handleMessage(final ActorRef sender, final Object message) {
+ if (message instanceof ElectionTimeout || message instanceof TimeoutNow) {
+ return handleElectionTimeout(message);
+ }
- Object message = fromSerializableMessage(originalMessage);
+ if (!(message instanceof RaftRPC)) {
+ // The rest of the processing requires the message to be a RaftRPC
+ return null;
+ }
- 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 follower's term {} - updating term",
- logName(), rpc.getTerm(), rpc, context.getTermInformation().getCurrentTerm());
+ final 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.info("{}: Term {} in \"{}\" message is greater than follower's term {} - updating term",
+ logName(), rpc.getTerm(), rpc, context.getTermInformation().getCurrentTerm());
- context.getTermInformation().updateAndPersist(rpc.getTerm(), null);
- }
+ context.getTermInformation().updateAndPersist(rpc.getTerm(), null);
+ }
+
+ if (rpc instanceof InstallSnapshot) {
+ handleInstallSnapshot(sender, (InstallSnapshot) rpc);
+ restartLastLeaderMessageTimer();
+ scheduleElection(electionDuration());
+ return this;
+ }
+
+ if (!(rpc instanceof RequestVote) || canGrantVote((RequestVote) rpc)) {
+ restartLastLeaderMessageTimer();
+ scheduleElection(electionDuration());
}
- if (message instanceof ElectionTimeout) {
- if(canStartElection()) {
- LOG.debug("{}: Received ElectionTimeout - switching to Candidate", logName());
+ return super.handleMessage(sender, rpc);
+ }
+
+ private RaftActorBehavior handleElectionTimeout(final Object message) {
+ // If the message is ElectionTimeout, verify we haven't actually seen a message from the leader
+ // during the election timeout interval. It may that the election timer expired b/c this actor
+ // was busy and messages got delayed, in which case leader messages would be backed up in the
+ // queue but would be processed before the ElectionTimeout message and thus would restart the
+ // lastLeaderMessageTimer.
+ long lastLeaderMessageInterval = lastLeaderMessageTimer.elapsed(TimeUnit.MILLISECONDS);
+ long electionTimeoutInMillis = context.getConfigParams().getElectionTimeOutInterval().toMillis();
+ boolean noLeaderMessageReceived = !lastLeaderMessageTimer.isRunning()
+ || lastLeaderMessageInterval >= electionTimeoutInMillis;
+
+ if (canStartElection()) {
+ if (message instanceof TimeoutNow) {
+ log.debug("{}: Received TimeoutNow - switching to Candidate", logName());
return internalSwitchBehavior(RaftState.Candidate);
+ } else if (noLeaderMessageReceived) {
+ // Check the cluster state to see if the leader is known to be up before we go to Candidate.
+ // However if we haven't heard from the leader in a long time even though the cluster state
+ // indicates it's up then something is wrong - leader might be stuck indefinitely - so switch
+ // to Candidate,
+ long maxElectionTimeout = electionTimeoutInMillis * MAX_ELECTION_TIMEOUT_FACTOR;
+ if (isLeaderAvailabilityKnown() && lastLeaderMessageInterval < maxElectionTimeout) {
+ log.debug("{}: Received ElectionTimeout but leader appears to be available", logName());
+ scheduleElection(electionDuration());
+ } else {
+ log.debug("{}: Received ElectionTimeout - switching to Candidate", logName());
+ return internalSwitchBehavior(RaftState.Candidate);
+ }
} else {
- return this;
+ log.debug("{}: Received ElectionTimeout but lastLeaderMessageInterval {} < election timeout {}",
+ logName(), lastLeaderMessageInterval, context.getConfigParams().getElectionTimeOutInterval());
+ scheduleElection(electionDuration());
+ }
+ } else if (message instanceof ElectionTimeout) {
+ if (noLeaderMessageReceived) {
+ setLeaderId(null);
}
- } else if (message instanceof InstallSnapshot) {
- InstallSnapshot installSnapshot = (InstallSnapshot) message;
- handleInstallSnapshot(sender, installSnapshot);
+ scheduleElection(electionDuration());
}
- if(message instanceof RaftRPC && (!(message instanceof RequestVote) || (canGrantVote((RequestVote) message)))){
- scheduleElection(electionDuration());
+ return this;
+ }
+
+ private boolean isLeaderAvailabilityKnown() {
+ if (leaderId == null) {
+ return false;
+ }
+
+ Optional<Cluster> cluster = context.getCluster();
+ if (!cluster.isPresent()) {
+ return false;
+ }
+
+ ActorSelection leaderActor = context.getPeerActorSelection(leaderId);
+ if (leaderActor == null) {
+ return false;
+ }
+
+ Address leaderAddress = leaderActor.anchorPath().address();
+
+ CurrentClusterState state = cluster.get().state();
+ Set<Member> unreachable = state.getUnreachable();
+
+ log.debug("{}: Checking for leader {} in the cluster unreachable set {}", logName(), leaderAddress,
+ unreachable);
+
+ for (Member m: unreachable) {
+ if (leaderAddress.equals(m.address())) {
+ log.info("{}: Leader {} is unreachable", logName(), leaderAddress);
+ return false;
+ }
}
- return super.handleMessage(sender, message);
+ for (Member m: state.getMembers()) {
+ if (leaderAddress.equals(m.address())) {
+ if (m.status() == MemberStatus.up() || m.status() == MemberStatus.weaklyUp()) {
+ log.debug("{}: Leader {} cluster status is {} - leader is available", logName(),
+ leaderAddress, m.status());
+ return true;
+ } else {
+ log.debug("{}: Leader {} cluster status is {} - leader is unavailable", logName(),
+ leaderAddress, m.status());
+ return false;
+ }
+ }
+ }
+
+ log.debug("{}: Leader {} not found in the cluster member set", logName(), leaderAddress);
+
+ return false;
}
- private void handleInstallSnapshot(final ActorRef sender, InstallSnapshot installSnapshot) {
+ private void handleInstallSnapshot(final ActorRef sender, final InstallSnapshot installSnapshot) {
- LOG.debug("{}: handleInstallSnapshot: {}", logName(), installSnapshot);
+ log.debug("{}: handleInstallSnapshot: {}", logName(), installSnapshot);
leaderId = installSnapshot.getLeaderId();
- if(snapshotTracker == null){
- snapshotTracker = new SnapshotTracker(LOG, installSnapshot.getTotalChunks());
+ if (snapshotTracker == null) {
+ snapshotTracker = new SnapshotTracker(log, installSnapshot.getTotalChunks(), installSnapshot.getLeaderId(),
+ context);
}
updateInitialSyncStatus(installSnapshot.getLastIncludedIndex(), installSnapshot.getLeaderId());
final InstallSnapshotReply reply = new InstallSnapshotReply(
currentTerm(), context.getId(), installSnapshot.getChunkIndex(), true);
- if(snapshotTracker.addChunk(installSnapshot.getChunkIndex(), installSnapshot.getData(),
- installSnapshot.getLastChunkHashCode())){
- Snapshot snapshot = Snapshot.create(snapshotTracker.getSnapshot(),
- new ArrayList<ReplicatedLogEntry>(),
+ if (snapshotTracker.addChunk(installSnapshot.getChunkIndex(), installSnapshot.getData(),
+ installSnapshot.getLastChunkHashCode())) {
+
+ log.info("{}: Snapshot installed from leader: {}", logName(), installSnapshot.getLeaderId());
+
+ Snapshot snapshot = Snapshot.create(
+ context.getSnapshotManager().convertSnapshot(snapshotTracker.getSnapshotBytes()),
+ new ArrayList<>(),
installSnapshot.getLastIncludedIndex(),
installSnapshot.getLastIncludedTerm(),
installSnapshot.getLastIncludedIndex(),
installSnapshot.getLastIncludedTerm(),
context.getTermInformation().getCurrentTerm(),
context.getTermInformation().getVotedFor(),
- context.getPeerServerInfo(true));
+ installSnapshot.getServerConfig().orNull());
ApplySnapshot.Callback applySnapshotCallback = new ApplySnapshot.Callback() {
@Override
public void onSuccess() {
- LOG.debug("{}: handleInstallSnapshot returning: {}", logName(), reply);
+ log.debug("{}: handleInstallSnapshot returning: {}", logName(), reply);
sender.tell(reply, actor());
}
actor().tell(new ApplySnapshot(snapshot, applySnapshotCallback), actor());
- snapshotTracker = null;
+ closeSnapshotTracker();
} else {
- LOG.debug("{}: handleInstallSnapshot returning: {}", logName(), reply);
+ log.debug("{}: handleInstallSnapshot returning: {}", logName(), reply);
sender.tell(reply, actor());
}
- } catch (SnapshotTracker.InvalidChunkException e) {
- LOG.debug("{}: Exception in InstallSnapshot of follower", logName(), e);
+ } catch (IOException e) {
+ log.debug("{}: Exception in InstallSnapshot of follower", logName(), e);
sender.tell(new InstallSnapshotReply(currentTerm(), context.getId(),
-1, false), actor());
- snapshotTracker = null;
- } catch (Exception e){
- LOG.error("{}: Exception in InstallSnapshot of follower", logName(), e);
-
- //send reply with success as false. The chunk will be sent again on failure
- sender.tell(new InstallSnapshotReply(currentTerm(), context.getId(),
- installSnapshot.getChunkIndex(), false), actor());
+ closeSnapshotTracker();
+ }
+ }
+ private void closeSnapshotTracker() {
+ if (snapshotTracker != null) {
+ snapshotTracker.close();
+ snapshotTracker = null;
}
}
@Override
- public void close() throws Exception {
+ public void close() {
+ closeSnapshotTracker();
stopElection();
}
@VisibleForTesting
- SnapshotTracker getSnapshotTracker(){
+ SnapshotTracker getSnapshotTracker() {
return snapshotTracker;
}
}
Code Review / controller.git / blobdiff