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;
-
/**
* The behavior of a RaftActor when it is in the CandidateState
- * <p>
+ * <p/>
* Candidates (§5.2):
* <ul>
* <li> On conversion to candidate, start election:
* </ul>
*/
public class Candidate extends AbstractRaftActorBehavior {
- private final List<String> peers;
- public Candidate(RaftActorContext context, List<String> peers) {
- super(context);
- this.peers = peers;
+ private int voteCount;
+
+ private final int votesRequired;
+
+ private final Collection<String> votingPeers = new ArrayList<>();
+
+ public Candidate(RaftActorContext context) {
+ super(context, RaftState.Candidate);
+
+ for(PeerInfo peer: context.getPeers()) {
+ if(peer.isVoting()) {
+ votingPeers.add(peer.getId());
+ }
+ }
+
+ if(LOG.isDebugEnabled()) {
+ 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) {
+
+ if(LOG.isDebugEnabled()) {
+ 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.debug("{}: New Leader sent an append entry to Candidate for term {} will switch to Follower",
+ logName(), currentTerm());
+
+ return switchBehavior(new Follower(context));
+ }
+
+ return this;
}
- @Override protected RaftState handleRequestVoteReply(ActorRef sender,
- RequestVoteReply requestVoteReply, RaftState suggestedState) {
- return suggestedState;
+ @Override
+ protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender, AppendEntriesReply appendEntriesReply) {
+ return this;
}
- @Override protected RaftState state() {
- return RaftState.Candidate;
+ @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.getCommitIndex() < context.getReplicatedLog().lastIndex()) {
+ LOG.debug("{}: Connmit index {} is behind last index {}", logName(), context.getCommitIndex(),
+ context.getReplicatedLog().lastIndex());
+ return internalSwitchBehavior(RaftState.PreLeader);
+ } else {
+ return internalSwitchBehavior(RaftState.Leader);
+ }
+ }
+
+ return this;
}
@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;
+
+ if(LOG.isDebugEnabled()) {
+ 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()) {
+ 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.debug("{}: Starting new 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();
+ }
}
Code Review / controller.git / blobdiff