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.Preconditions;
+import com.google.common.base.Stopwatch;
import java.util.ArrayList;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+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;
/**
* The behavior of a RaftActor in the Follower state
public class Follower extends AbstractRaftActorBehavior {
private static final int SYNC_THRESHOLD = 10;
+ private static final long MAX_ELECTION_TIMEOUT_FACTOR = 18;
+
private final SyncStatusTracker initialSyncStatusTracker;
- private final Procedure<ReplicatedLogEntry> appendAndPersistCallback = new Procedure<ReplicatedLogEntry>() {
- @Override
- public void apply(ReplicatedLogEntry logEntry) {
- context.getReplicatedLog().captureSnapshotIfReady(logEntry);
- }
- };
+ private final Procedure<ReplicatedLogEntry> appendAndPersistCallback =
+ logEntry -> context.getReplicatedLog().captureSnapshotIfReady(logEntry);
+ private final Stopwatch lastLeaderMessageTimer = Stopwatch.createStarted();
private SnapshotTracker snapshotTracker = null;
private String leaderId;
private short leaderPayloadVersion;
initialSyncStatusTracker = new SyncStatusTracker(context.getActor(), getId(), SYNC_THRESHOLD);
- if(canStartElection()) {
- if (context.getPeerIds().isEmpty() && getLeaderId() == null) {
- actor().tell(ElectionTimeout.INSTANCE, actor());
- } else {
- scheduleElection(electionDuration());
- }
+ if (context.getPeerIds().isEmpty() && getLeaderId() == null) {
+ actor().tell(TimeoutNow.INSTANCE, actor());
+ } else {
+ scheduleElection(electionDuration());
}
}
}
@VisibleForTesting
- protected final void setLeaderId(final String leaderId) {
- this.leaderId = Preconditions.checkNotNull(leaderId);
+ protected final void setLeaderId(@Nullable final String leaderId) {
+ this.leaderId = leaderId;
}
@Override
this.leaderPayloadVersion = leaderPayloadVersion;
}
- private boolean isLogEntryPresent(long index){
- if(context.getReplicatedLog().isInSnapshot(index)) {
- return true;
+ private void restartLastLeaderMessageTimer() {
+ if (lastLeaderMessageTimer.isRunning()) {
+ lastLeaderMessageTimer.reset();
}
- ReplicatedLogEntry previousEntry = context.getReplicatedLog()
- .get(index);
-
- return previousEntry != null;
-
+ lastLeaderMessageTimer.start();
}
- private long getLogEntryTerm(long index){
- if(index == context.getReplicatedLog().getSnapshotIndex()){
- return context.getReplicatedLog().getSnapshotTerm();
+ private boolean isLogEntryPresent(long index){
+ if(context.getReplicatedLog().isInSnapshot(index)) {
+ return true;
}
- ReplicatedLogEntry previousEntry = context.getReplicatedLog()
- .get(index);
+ ReplicatedLogEntry entry = context.getReplicatedLog().get(index);
+ return entry != null;
- if(previousEntry != null){
- return previousEntry.getTerm();
- }
-
- return -1;
}
private void updateInitialSyncStatus(long currentLeaderCommit, String leaderId){
// 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());
+ snapshotTracker = null;
+ }
+
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,
// 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;
}
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.debug("{}: Could not remove entries - sending reply to force snapshot", logName());
+ sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex,
+ lastTerm(), context.getPayloadVersion(), true), actor());
+ return this;
+ }
+
break;
} else {
sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex,
}
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);
// 4. Append any new entries not already in the log
for (int i = addEntriesFrom; i < appendEntries.getEntries().size(); i++) {
}
@Override
- public RaftActorBehavior handleMessage(ActorRef sender, Object originalMessage) {
- if (originalMessage instanceof ElectionTimeout) {
- if (canStartElection()) {
- LOG.debug("{}: Received ElectionTimeout - switching to Candidate", logName());
- return internalSwitchBehavior(RaftState.Candidate);
- } else {
- return this;
- }
+ public RaftActorBehavior handleMessage(ActorRef sender, Object message) {
+ if (message instanceof ElectionTimeout || message instanceof TimeoutNow) {
+ return handleElectionTimeout(message);
}
- final Object message = fromSerializableMessage(originalMessage);
if (!(message instanceof RaftRPC)) {
// The rest of the processing requires the message to be a RaftRPC
return null;
}
if (rpc instanceof InstallSnapshot) {
- InstallSnapshot installSnapshot = (InstallSnapshot) rpc;
- handleInstallSnapshot(sender, installSnapshot);
+ handleInstallSnapshot(sender, (InstallSnapshot) rpc);
+ restartLastLeaderMessageTimer();
scheduleElection(electionDuration());
return this;
}
if (!(rpc instanceof RequestVote) || canGrantVote((RequestVote) rpc)) {
+ restartLastLeaderMessageTimer();
scheduleElection(electionDuration());
}
return super.handleMessage(sender, rpc);
}
+ private RaftActorBehavior handleElectionTimeout(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 {
+ LOG.debug("{}: Received ElectionTimeout but lastLeaderMessageInterval {} < election timeout {}",
+ logName(), lastLeaderMessageInterval, context.getConfigParams().getElectionTimeOutInterval());
+ scheduleElection(electionDuration());
+ }
+ } else if(message instanceof ElectionTimeout) {
+ if(noLeaderMessageReceived) {
+ setLeaderId(null);
+ }
+
+ 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;
+ }
+ }
+
+ 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) {
LOG.debug("{}: handleInstallSnapshot: {}", logName(), installSnapshot);
leaderId = installSnapshot.getLeaderId();
if(snapshotTracker == null){
- snapshotTracker = new SnapshotTracker(LOG, installSnapshot.getTotalChunks());
+ snapshotTracker = new SnapshotTracker(LOG, installSnapshot.getTotalChunks(), installSnapshot.getLeaderId());
}
updateInitialSyncStatus(installSnapshot.getLastIncludedIndex(), installSnapshot.getLeaderId());
installSnapshot.getLastIncludedTerm(),
context.getTermInformation().getCurrentTerm(),
context.getTermInformation().getVotedFor(),
- context.getPeerServerInfo(true));
+ installSnapshot.getServerConfig().orNull());
ApplySnapshot.Callback applySnapshotCallback = new ApplySnapshot.Callback() {
@Override
Code Review / controller.git / blobdiff