X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-akka-raft%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fcluster%2Fraft%2Fbehaviors%2FLeader.java;h=a50666233c31f30b2e94cbf4c49d53a95cca93f4;hb=c74d5c2399e500fe3e690edc8cee497b1cb6f867;hp=c06ee9bd2b836c784c4adb75e7f318875ebf22c3;hpb=fdab53ef9033fc83c812f7d3d6d3327d3d176f0f;p=controller.git diff --git a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Leader.java b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Leader.java index c06ee9bd2b..a50666233c 100644 --- a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Leader.java +++ b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Leader.java @@ -19,18 +19,24 @@ import org.opendaylight.controller.cluster.raft.FollowerLogInformationImpl; 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.internal.messages.ApplyState; -import org.opendaylight.controller.cluster.raft.internal.messages.Replicate; -import org.opendaylight.controller.cluster.raft.internal.messages.SendHeartBeat; +import org.opendaylight.controller.cluster.raft.base.messages.ApplyState; +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.AppendEntries; import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply; +import org.opendaylight.controller.cluster.raft.messages.InstallSnapshot; +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 scala.concurrent.duration.FiniteDuration; import java.util.ArrayList; +import java.util.Collections; import java.util.HashMap; import java.util.List; import java.util.Map; +import java.util.Set; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicLong; @@ -62,9 +68,11 @@ public class Leader extends AbstractRaftActorBehavior { private final Map followerToLog = new HashMap(); - private final Map followerToActor = new HashMap<>(); + private final Set followers; - private Cancellable heartbeatCancel = null; + private Cancellable heartbeatSchedule = null; + private Cancellable appendEntriesSchedule = null; + private Cancellable installSnapshotSchedule = null; private List trackerList = new ArrayList<>(); @@ -73,25 +81,25 @@ public class Leader extends AbstractRaftActorBehavior { public Leader(RaftActorContext context) { super(context); - if(lastIndex() >= 0) { + if (lastIndex() >= 0) { context.setCommitIndex(lastIndex()); } - for (String followerId : context.getPeerAddresses().keySet()) { + followers = context.getPeerAddresses().keySet(); + + for (String followerId : followers) { FollowerLogInformation followerLogInformation = new FollowerLogInformationImpl(followerId, new AtomicLong(lastIndex()), new AtomicLong(-1)); - followerToActor.put(followerId, - context.actorSelection(context.getPeerAddress(followerId))); - followerToLog.put(followerId, followerLogInformation); - } - if (followerToActor.size() > 0) { - minReplicationCount = (followerToActor.size() + 1) / 2 + 1; + context.getLogger().debug("Election:Leader has following peers:"+ followers); + + if (followers.size() > 0) { + minReplicationCount = (followers.size() + 1) / 2 + 1; } else { minReplicationCount = 0; } @@ -103,35 +111,52 @@ public class Leader extends AbstractRaftActorBehavior { // prevent election timeouts (§5.2) scheduleHeartBeat(new FiniteDuration(0, TimeUnit.SECONDS)); + scheduleInstallSnapshotCheck( + new FiniteDuration(context.getConfigParams().getHeartBeatInterval().length() * 1000, + context.getConfigParams().getHeartBeatInterval().unit()) + ); } @Override protected RaftState handleAppendEntries(ActorRef sender, - AppendEntries appendEntries, RaftState suggestedState) { + AppendEntries appendEntries) { - context.getLogger() - .error("An unexpected AppendEntries received in state " + state()); + context.getLogger().info("Leader: Received {}", appendEntries.toString()); - return suggestedState; + return state(); } @Override protected RaftState handleAppendEntriesReply(ActorRef sender, - AppendEntriesReply appendEntriesReply, RaftState suggestedState) { + AppendEntriesReply appendEntriesReply) { - // Do not take any other action since a behavior change is coming - if (suggestedState != state()) - return suggestedState; + if(! appendEntriesReply.isSuccess()) { + context.getLogger() + .info("Leader: Received {}", appendEntriesReply.toString()); + } // Update the FollowerLogInformation String followerId = appendEntriesReply.getFollowerId(); FollowerLogInformation followerLogInformation = followerToLog.get(followerId); + + if(followerLogInformation == null){ + context.getLogger().error("Unknown follower {}", followerId); + return state(); + } + if (appendEntriesReply.isSuccess()) { followerLogInformation .setMatchIndex(appendEntriesReply.getLogLastIndex()); followerLogInformation .setNextIndex(appendEntriesReply.getLogLastIndex() + 1); } else { + + // 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 + followerLogInformation.decrNextIndex(); } @@ -148,7 +173,7 @@ public class Leader extends AbstractRaftActorBehavior { } } - if (replicatedCount >= minReplicationCount){ + if (replicatedCount >= minReplicationCount) { ReplicatedLogEntry replicatedLogEntry = context.getReplicatedLog().get(N); if (replicatedLogEntry != null @@ -161,11 +186,12 @@ public class Leader extends AbstractRaftActorBehavior { } } - if(context.getCommitIndex() > context.getLastApplied()){ + // Apply the change to the state machine + if (context.getCommitIndex() > context.getLastApplied()) { applyLogToStateMachine(context.getCommitIndex()); } - return suggestedState; + return state(); } protected ClientRequestTracker findClientRequestTracker(long logIndex) { @@ -179,112 +205,182 @@ public class Leader extends AbstractRaftActorBehavior { } @Override protected RaftState handleRequestVoteReply(ActorRef sender, - RequestVoteReply requestVoteReply, RaftState suggestedState) { - return suggestedState; + RequestVoteReply requestVoteReply) { + return state(); } @Override public RaftState state() { return RaftState.Leader; } - @Override public RaftState handleMessage(ActorRef sender, Object message) { + @Override public RaftState handleMessage(ActorRef sender, Object originalMessage) { 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()) { + context.getTermInformation().updateAndPersist(rpc.getTerm(), null); + return RaftState.Follower; + } + } + try { if (message instanceof SendHeartBeat) { return sendHeartBeat(); + } else if(message instanceof SendInstallSnapshot) { + installSnapshotIfNeeded(); } else if (message instanceof Replicate) { + replicate((Replicate) message); + } else if (message instanceof InstallSnapshotReply){ + handleInstallSnapshotReply( + (InstallSnapshotReply) message); + } + } finally { + scheduleHeartBeat(context.getConfigParams().getHeartBeatInterval()); + } - Replicate replicate = (Replicate) message; - long logIndex = replicate.getReplicatedLogEntry().getIndex(); + return super.handleMessage(sender, message); + } - context.getLogger().debug("Replicate message " + logIndex); + private void handleInstallSnapshotReply(InstallSnapshotReply message) { + InstallSnapshotReply reply = message; + String followerId = reply.getFollowerId(); + FollowerLogInformation followerLogInformation = + followerToLog.get(followerId); + + followerLogInformation + .setMatchIndex(context.getReplicatedLog().getSnapshotIndex()); + followerLogInformation + .setNextIndex(context.getReplicatedLog().getSnapshotIndex() + 1); + } - if (followerToActor.size() == 0) { - context.setCommitIndex( - replicate.getReplicatedLogEntry().getIndex()); + private void replicate(Replicate replicate) { + long logIndex = replicate.getReplicatedLogEntry().getIndex(); + context.getLogger().debug("Replicate message " + logIndex); + + if (followers.size() == 0) { + context.setCommitIndex( + replicate.getReplicatedLogEntry().getIndex()); + + context.getActor() + .tell(new ApplyState(replicate.getClientActor(), + replicate.getIdentifier(), + replicate.getReplicatedLogEntry()), context.getActor() - .tell(new ApplyState(replicate.getClientActor(), - replicate.getIdentifier(), - replicate.getReplicatedLogEntry()), - context.getActor() - ); - } else { - - trackerList.add( - new ClientRequestTrackerImpl(replicate.getClientActor(), - replicate.getIdentifier(), - logIndex) - ); + ); + } else { - ReplicatedLogEntry prevEntry = - context.getReplicatedLog().get(lastIndex() - 1); - long prevLogIndex = -1; - long prevLogTerm = -1; - if (prevEntry != null) { - prevLogIndex = prevEntry.getIndex(); - prevLogTerm = prevEntry.getTerm(); - } - // Send an AppendEntries to all followers - for (String followerId : followerToActor.keySet()) { - ActorSelection followerActor = - followerToActor.get(followerId); - FollowerLogInformation followerLogInformation = - followerToLog.get(followerId); - followerActor.tell( - new AppendEntries(currentTerm(), context.getId(), - prevLogIndex, prevLogTerm, - context.getReplicatedLog().getFrom( - followerLogInformation.getNextIndex() - .get() - ), context.getCommitIndex() - ), - actor() - ); - } - } - } - } finally { - scheduleHeartBeat(HEART_BEAT_INTERVAL); - } + // Create a tracker entry we will use this later to notify the + // client actor + trackerList.add( + new ClientRequestTrackerImpl(replicate.getClientActor(), + replicate.getIdentifier(), + logIndex) + ); - return super.handleMessage(sender, message); + sendAppendEntries(); + } } - private RaftState sendHeartBeat() { - if (followerToActor.size() > 0) { - for (String follower : followerToActor.keySet()) { + private void sendAppendEntries() { + // Send an AppendEntries to all followers + for (String followerId : followers) { + ActorSelection followerActor = + context.getPeerActorSelection(followerId); + if (followerActor != null) { FollowerLogInformation followerLogInformation = - followerToLog.get(follower); + followerToLog.get(followerId); - AtomicLong nextIndex = - followerLogInformation.getNextIndex(); + long nextIndex = followerLogInformation.getNextIndex().get(); - List entries = - context.getReplicatedLog().getFrom(nextIndex.get()); + List entries = Collections.emptyList(); - followerToActor.get(follower).tell(new AppendEntries( - context.getTermInformation().getCurrentTerm(), - context.getId(), - context.getReplicatedLog().lastIndex(), - context.getReplicatedLog().lastTerm(), - entries, context.getCommitIndex()), - context.getActor() + if (context.getReplicatedLog().isPresent(nextIndex)) { + // TODO: Instead of sending all entries from nextIndex + // only send a fixed number of entries to each follower + // This is to avoid the situation where there are a lot of + // entries to install for a fresh follower or to a follower + // that has fallen too far behind with the log but yet is not + // eligible to receive a snapshot + entries = + context.getReplicatedLog().getFrom(nextIndex, 1); + } + + followerActor.tell( + new AppendEntries(currentTerm(), context.getId(), + prevLogIndex(nextIndex), + prevLogTerm(nextIndex), entries, + context.getCommitIndex()).toSerializable(), + 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. + */ + private void installSnapshotIfNeeded(){ + for (String followerId : followers) { + ActorSelection followerActor = + context.getPeerActorSelection(followerId); + + if(followerActor != null) { + FollowerLogInformation followerLogInformation = + followerToLog.get(followerId); + + long nextIndex = followerLogInformation.getNextIndex().get(); + + if (!context.getReplicatedLog().isPresent(nextIndex) && context + .getReplicatedLog().isInSnapshot(nextIndex)) { + followerActor.tell( + new InstallSnapshot(currentTerm(), context.getId(), + context.getReplicatedLog().getSnapshotIndex(), + context.getReplicatedLog().getSnapshotTerm(), + context.getReplicatedLog().getSnapshot() + ), + actor() + ); + } + } + } + } + + private RaftState sendHeartBeat() { + if (followers.size() > 0) { + sendAppendEntries(); + } return state(); } private void stopHeartBeat() { - if (heartbeatCancel != null && !heartbeatCancel.isCancelled()) { - heartbeatCancel.cancel(); + if (heartbeatSchedule != null && !heartbeatSchedule.isCancelled()) { + heartbeatSchedule.cancel(); + } + } + + private void stopInstallSnapshotSchedule() { + if (installSnapshotSchedule != null && !installSnapshotSchedule.isCancelled()) { + installSnapshotSchedule.cancel(); } } private void scheduleHeartBeat(FiniteDuration interval) { + if(followers.size() == 0){ + // Optimization - do not bother scheduling a heartbeat as there are + // no followers + return; + } + stopHeartBeat(); // Schedule a heartbeat. When the scheduler triggers a SendHeartbeat @@ -292,13 +388,34 @@ public class Leader extends AbstractRaftActorBehavior { // Scheduling the heartbeat only once here because heartbeats do not // need to be sent if there are other messages being sent to the remote // actor. - heartbeatCancel = + heartbeatSchedule = context.getActorSystem().scheduler().scheduleOnce( interval, context.getActor(), new SendHeartBeat(), context.getActorSystem().dispatcher(), context.getActor()); } + + private void scheduleInstallSnapshotCheck(FiniteDuration interval) { + if(followers.size() == 0){ + // Optimization - do not bother scheduling a heartbeat as there are + // no followers + return; + } + + stopInstallSnapshotSchedule(); + + // Schedule a message to send append entries to followers that can + // accept an append entries with some data in it + installSnapshotSchedule = + context.getActorSystem().scheduler().scheduleOnce( + interval, + context.getActor(), new SendInstallSnapshot(), + context.getActorSystem().dispatcher(), context.getActor()); + } + + + @Override public void close() throws Exception { stopHeartBeat(); }