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.internal.messages.ElectionTimeout;
+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.Collection;
-import java.util.HashMap;
-import java.util.Map;
-
/**
* The behavior of a RaftActor when it is in the CandidateState
* <p/>
*/
public class Candidate extends AbstractRaftActorBehavior {
- private final Map<String, ActorSelection> peerToActor = new HashMap<>();
-
private int voteCount;
private final int votesRequired;
- public Candidate(RaftActorContext context) {
- super(context);
+ private final Collection<String> votingPeers = new ArrayList<>();
- Collection<String> peerPaths = context.getPeerAddresses().values();
+ public Candidate(RaftActorContext context) {
+ super(context, RaftState.Candidate);
- for (String peerPath : peerPaths) {
- peerToActor.put(peerPath,
- context.actorSelection(peerPath));
+ for(PeerInfo peer: context.getPeers()) {
+ if(peer.isVoting()) {
+ votingPeers.add(peer.getId());
+ }
}
- context.getLogger().debug("Election:Candidate has following peers:"+peerToActor.keySet());
- if(peerPaths.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 = peerPaths.size();
- int self = 1;
- votesRequired = (noOfPeers + self) / 2 + 1;
- } else {
- votesRequired = 0;
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: Election: Candidate has following voting peers: {}", logName(), votingPeers);
}
- startNewTerm();
- scheduleElection(electionDuration());
- }
+ votesRequired = getMajorityVoteCount(votingPeers.size());
- @Override protected RaftState handleAppendEntries(ActorRef sender,
- AppendEntries appendEntries) {
+ startNewTerm();
- return state();
+ if(votingPeers.isEmpty()){
+ actor().tell(ElectionTimeout.INSTANCE, actor());
+ } else {
+ scheduleElection(electionDuration());
+ }
}
- @Override protected RaftState handleAppendEntriesReply(ActorRef sender,
- AppendEntriesReply appendEntriesReply) {
+ @Override
+ public final String getLeaderId() {
+ return null;
+ }
- return state();
+ @Override
+ public final short getLeaderPayloadVersion() {
+ return -1;
}
- @Override protected RaftState handleRequestVoteReply(ActorRef sender,
- RequestVoteReply requestVoteReply) {
+ @Override
+ protected RaftActorBehavior handleAppendEntries(ActorRef sender,
+ AppendEntries appendEntries) {
- if (requestVoteReply.isVoteGranted()) {
- voteCount++;
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: handleAppendEntries: {}", logName(), appendEntries);
}
- if (voteCount >= votesRequired) {
- return RaftState.Leader;
+ // 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 state();
+ return this;
}
- @Override public RaftState state() {
- return RaftState.Candidate;
+ @Override
+ protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender, AppendEntriesReply appendEntriesReply) {
+ return this;
}
@Override
- public RaftState handleMessage(ActorRef sender, Object message) {
+ protected RaftActorBehavior handleRequestVoteReply(ActorRef sender, RequestVoteReply requestVoteReply) {
+ LOG.debug("{}: handleRequestVoteReply: {}, current voteCount: {}", logName(), requestVoteReply, voteCount);
- 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;
+ 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 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 RaftState.Leader;
+
+ return internalSwitchBehavior(RaftState.Leader);
}
+
startNewTerm();
scheduleElection(electionDuration());
- return state();
+ 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);
}
// 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.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 (ActorSelection peerActor : peerToActor.values()) {
- peerActor.tell(new RequestVote(
- context.getTermInformation().getCurrentTerm(),
- context.getId(),
- context.getReplicatedLog().lastIndex(),
- context.getReplicatedLog().lastTerm()),
- context.getActor()
- );
+ 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() throws Exception {
+ @Override
+ public void close() {
stopElection();
}
}
Code Review / controller.git / blobdiff