X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?p=controller.git;a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-akka-raft%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fcluster%2Fraft%2Fbehaviors%2FCandidate.java;h=569f6b3d245fe5a6c1021f0537f08b3e1ec36f6e;hp=c125bd32b60a5c5d714ea13e7008417f904d88dc;hb=e84f63ee098fff5b02cbce1281ca0d1208f966fa;hpb=5ffd4b46ca00fc8f3d801050670c890117dc0811 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 c125bd32b6..569f6b3d24 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 @@ -5,25 +5,29 @@ * terms of the Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html */ - 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.ReplicatedLogEntry; +import org.opendaylight.controller.cluster.raft.base.messages.ApplyState; 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.Set; +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 { +public final class Candidate extends AbstractRaftActorBehavior { private int voteCount; private final int votesRequired; - private final Set peers; - - public Candidate(RaftActorContext context) { - super(context); - - peers = context.getPeerAddresses().keySet(); - - context.getLogger().debug("Election:Candidate has following peers:"+ peers); - - if(peers.size() > 0) { - // Votes are required from a majority of the peers including self. - // The votesRequired field therefore stores a calculated value - // of the number of votes required for this candidate to win an - // election based on it's known peers. - // If a peer was added during normal operation and raft replicas - // came to know about them then the new peer would also need to be - // taken into consideration when calculating this value. - // Here are some examples for what the votesRequired would be for n - // peers - // 0 peers = 1 votesRequired (0 + 1) / 2 + 1 = 1 - // 2 peers = 2 votesRequired (2 + 1) / 2 + 1 = 2 - // 4 peers = 3 votesRequired (4 + 1) / 2 + 1 = 3 - int noOfPeers = peers.size(); - int self = 1; - votesRequired = (noOfPeers + self) / 2 + 1; - } else { - votesRequired = 0; + private final Collection votingPeers = new ArrayList<>(); + + public Candidate(final 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(); - scheduleElection(electionDuration()); - } - @Override protected RaftState handleAppendEntries(ActorRef sender, - AppendEntries appendEntries) { + if (votingPeers.isEmpty()) { + actor().tell(ElectionTimeout.INSTANCE, actor()); + } else { + scheduleElection(electionDuration()); + } + } - context.getLogger().info("Candidate: Received {}", appendEntries.toString()); + @Override + public String getLeaderId() { + return null; + } - return state(); + @Override + public short getLeaderPayloadVersion() { + return -1; } - @Override protected RaftState handleAppendEntriesReply(ActorRef sender, - AppendEntriesReply appendEntriesReply) { + @Override + protected RaftActorBehavior handleAppendEntries(final ActorRef sender, final 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; + } - return state(); + @Override + protected RaftActorBehavior handleAppendEntriesReply(final ActorRef sender, + final AppendEntriesReply appendEntriesReply) { + return this; } - @Override protected RaftState handleRequestVoteReply(ActorRef sender, - RequestVoteReply requestVoteReply) { + @Override + protected RaftActorBehavior handleRequestVoteReply(final ActorRef sender, final RequestVoteReply requestVoteReply) { + log.debug("{}: handleRequestVoteReply: {}, current voteCount: {}", logName(), requestVoteReply, voteCount); if (requestVoteReply.isVoteGranted()) { voteCount++; } if (voteCount >= votesRequired) { - return RaftState.Leader; + 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 state(); + return this; + } + + @Override + protected FiniteDuration electionDuration() { + return super.electionDuration().$div(context.getConfigParams().getCandidateElectionTimeoutDivisor()); } - @Override public RaftState state() { - return RaftState.Candidate; + + @Override + ApplyState getApplyStateFor(final ReplicatedLogEntry entry) { + throw new IllegalStateException("A candidate should never attempt to apply " + entry); } @Override - public RaftState handleMessage(ActorRef sender, Object originalMessage) { + public RaftActorBehavior handleMessage(final ActorRef sender, final Object message) { + if (message instanceof ElectionTimeout) { + log.debug("{}: Received ElectionTimeout", logName()); - Object message = fromSerializableMessage(originalMessage); + 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; - context.getLogger().debug("RaftRPC message received {} my term is {}", rpc.toString(), context.getTermInformation().getCurrentTerm()); + 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); - return RaftState.Follower; - } - } - if (message instanceof ElectionTimeout) { - 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 RaftState.Leader; + // 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); } - startNewTerm(); - scheduleElection(electionDuration()); - return state(); } 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(); - context.getTermInformation().updateAndPersist(currentTerm + 1, - context.getId()); + long newTerm = currentTerm + 1; + context.getTermInformation().updateAndPersist(newTerm, context.getId()); - context.getLogger().debug("Starting new term " + (currentTerm + 1)); + 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 : peers) { + for (String peerId : votingPeers) { ActorSelection peerActor = context.getPeerActorSelection(peerId); - if(peerActor != null) { - peerActor.tell(new RequestVote( + if (peerActor != null) { + RequestVote requestVote = new RequestVote( context.getTermInformation().getCurrentTerm(), context.getId(), context.getReplicatedLog().lastIndex(), - context.getReplicatedLog().lastTerm()), - context.getActor() - ); - } - } + context.getReplicatedLog().lastTerm()); + log.debug("{}: Sending {} to peer {}", logName(), requestVote, peerId); + peerActor.tell(requestVote, context.getActor()); + } + } } - @Override public void close() throws Exception { + @Override + public void close() { stopElection(); } }