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.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>() {
}
};
+ 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 (context.getPeerIds().isEmpty() && getLeaderId() == null) {
- actor().tell(ElectionTimeout.INSTANCE, actor());
+ actor().tell(TimeoutNow.INSTANCE, actor());
} else {
scheduleElection(electionDuration());
}
this.leaderPayloadVersion = leaderPayloadVersion;
}
+ private void restartLastLeaderMessageTimer() {
+ if (lastLeaderMessageTimer.isRunning()) {
+ lastLeaderMessageTimer.reset();
+ }
+
+ lastLeaderMessageTimer.start();
+ }
+
private boolean isLogEntryPresent(long index){
if(context.getReplicatedLog().isInSnapshot(index)) {
return true;
}
@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 {
- setLeaderId(null);
- scheduleElection(electionDuration());
- 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);