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%2FCandidate.java;h=c125bd32b60a5c5d714ea13e7008417f904d88dc;hb=e66759266dc43d5f58b2837aca5047b42c205e4a;hp=774691154a8ee4782e02532916ebb9c7f29734a5;hpb=583f6075e842a6a37b83bd01e478aebc70c6af73;p=controller.git diff --git a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Candidate.java b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Candidate.java index 774691154a..afa46892be 100644 --- a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Candidate.java +++ b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Candidate.java @@ -9,17 +9,23 @@ package org.opendaylight.controller.cluster.raft.behaviors; import akka.actor.ActorRef; +import akka.actor.ActorSelection; +import java.util.ArrayList; +import java.util.Collection; +import org.opendaylight.controller.cluster.raft.PeerInfo; import org.opendaylight.controller.cluster.raft.RaftActorContext; import org.opendaylight.controller.cluster.raft.RaftState; +import org.opendaylight.controller.cluster.raft.base.messages.ElectionTimeout; import org.opendaylight.controller.cluster.raft.messages.AppendEntries; import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply; +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 java.util.List; +import scala.concurrent.duration.FiniteDuration; /** - * The behavior of a RaftActor when it is in the CandidateState + * The behavior of a RaftActor when it is in the Candidate raft state. + * *

* Candidates (§5.2): *

*/ public class Candidate extends AbstractRaftActorBehavior { - private final List peers; - public Candidate(RaftActorContext context, List peers) { - super(context); - this.peers = peers; + private int voteCount; + + private final int votesRequired; + + private final Collection votingPeers = new ArrayList<>(); + + public Candidate(RaftActorContext context) { + super(context, RaftState.Candidate); + + for (PeerInfo peer: context.getPeers()) { + if (peer.isVoting()) { + votingPeers.add(peer.getId()); + } + } + + log.debug("{}: Election: Candidate has following voting peers: {}", logName(), votingPeers); + + votesRequired = getMajorityVoteCount(votingPeers.size()); + + startNewTerm(); + + if (votingPeers.isEmpty()) { + actor().tell(ElectionTimeout.INSTANCE, actor()); + } else { + scheduleElection(electionDuration()); + } } - @Override protected RaftState handleAppendEntries(ActorRef sender, - AppendEntries appendEntries, RaftState suggestedState) { - return suggestedState; + @Override + public final String getLeaderId() { + return null; } - @Override protected RaftState handleAppendEntriesReply(ActorRef sender, - AppendEntriesReply appendEntriesReply, RaftState suggestedState) { - return suggestedState; + @Override + public final short getLeaderPayloadVersion() { + return -1; } - @Override protected RaftState handleRequestVote(ActorRef sender, - RequestVote requestVote, RaftState suggestedState) { - return suggestedState; + @Override + protected RaftActorBehavior handleAppendEntries(ActorRef sender, AppendEntries appendEntries) { + + log.debug("{}: handleAppendEntries: {}", logName(), appendEntries); + + // Some other candidate for the same term became a leader and sent us an append entry + if (currentTerm() == appendEntries.getTerm()) { + log.info("{}: New Leader {} sent an AppendEntries to Candidate for term {} - will switch to Follower", + logName(), appendEntries.getLeaderId(), currentTerm()); + + return switchBehavior(new Follower(context)); + } + + return this; + } + + @Override + protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender, AppendEntriesReply appendEntriesReply) { + return this; } - @Override protected RaftState handleRequestVoteReply(ActorRef sender, - RequestVoteReply requestVoteReply, RaftState suggestedState) { - return suggestedState; + @Override + protected RaftActorBehavior handleRequestVoteReply(ActorRef sender, RequestVoteReply requestVoteReply) { + log.debug("{}: handleRequestVoteReply: {}, current voteCount: {}", logName(), requestVoteReply, voteCount); + + if (requestVoteReply.isVoteGranted()) { + voteCount++; + } + + if (voteCount >= votesRequired) { + if (context.getLastApplied() < context.getReplicatedLog().lastIndex()) { + log.info("{}: LastApplied index {} is behind last index {} - switching to PreLeader", + logName(), context.getLastApplied(), context.getReplicatedLog().lastIndex()); + return internalSwitchBehavior(RaftState.PreLeader); + } else { + return internalSwitchBehavior(RaftState.Leader); + } + } + + return this; } - @Override protected RaftState state() { - return RaftState.Candidate; + @Override + protected FiniteDuration electionDuration() { + return super.electionDuration().$div(context.getConfigParams().getCandidateElectionTimeoutDivisor()); } @Override - public RaftState handleMessage(ActorRef sender, Object message) { + public RaftActorBehavior handleMessage(ActorRef sender, Object message) { + if (message instanceof ElectionTimeout) { + log.debug("{}: Received ElectionTimeout", logName()); + + if (votesRequired == 0) { + // If there are no peers then we should be a Leader + // We wait for the election timeout to occur before declare + // ourselves the leader. This gives enough time for a leader + // who we do not know about (as a peer) + // to send a message to the candidate + + return internalSwitchBehavior(RaftState.Leader); + } + + startNewTerm(); + scheduleElection(electionDuration()); + return this; + } + + if (message instanceof RaftRPC) { + + RaftRPC rpc = (RaftRPC) message; + + log.debug("{}: RaftRPC message received {}, my term is {}", logName(), rpc, + context.getTermInformation().getCurrentTerm()); + + // 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 Candidate's term {} - switching to Follower", + logName(), rpc.getTerm(), rpc, context.getTermInformation().getCurrentTerm()); + + context.getTermInformation().updateAndPersist(rpc.getTerm(), null); + + // The raft paper does not say whether or not a Candidate can/should process a RequestVote in + // this case but doing so gains quicker convergence when the sender's log is more up-to-date. + if (message instanceof RequestVote) { + super.handleMessage(sender, message); + } + + return internalSwitchBehavior(RaftState.Follower); + } + } + return super.handleMessage(sender, message); } + + + private void startNewTerm() { + + + // set voteCount back to 1 (that is voting for self) + voteCount = 1; + + // Increment the election term and vote for self + long currentTerm = context.getTermInformation().getCurrentTerm(); + long newTerm = currentTerm + 1; + context.getTermInformation().updateAndPersist(newTerm, context.getId()); + + log.info("{}: Starting new election term {}", logName(), newTerm); + + // Request for a vote + // TODO: Retry request for vote if replies do not arrive in a reasonable + // amount of time TBD + for (String peerId : votingPeers) { + ActorSelection peerActor = context.getPeerActorSelection(peerId); + if (peerActor != null) { + RequestVote requestVote = new RequestVote( + context.getTermInformation().getCurrentTerm(), + context.getId(), + context.getReplicatedLog().lastIndex(), + context.getReplicatedLog().lastTerm()); + + log.debug("{}: Sending {} to peer {}", logName(), requestVote, peerId); + + peerActor.tell(requestVote, context.getActor()); + } + } + } + + @Override + public void close() { + stopElection(); + } }