2 * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
9 package org.opendaylight.controller.cluster.raft.behaviors;
11 import akka.actor.ActorRef;
12 import akka.actor.ActorSelection;
13 import org.opendaylight.controller.cluster.raft.RaftActorContext;
14 import org.opendaylight.controller.cluster.raft.RaftState;
15 import org.opendaylight.controller.cluster.raft.base.messages.ElectionTimeout;
16 import org.opendaylight.controller.cluster.raft.messages.AppendEntries;
17 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
18 import org.opendaylight.controller.cluster.raft.messages.RaftRPC;
19 import org.opendaylight.controller.cluster.raft.messages.RequestVote;
20 import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply;
25 * The behavior of a RaftActor when it is in the CandidateState
29 * <li> On conversion to candidate, start election:
31 * <li> Increment currentTerm
33 * <li> Reset election timer
34 * <li> Send RequestVote RPCs to all other servers
36 * <li> If votes received from majority of servers: become leader
37 * <li> If AppendEntries RPC received from new leader: convert to
39 * <li> If election timeout elapses: start new election
42 public class Candidate extends AbstractRaftActorBehavior {
44 private int voteCount;
46 private final int votesRequired;
48 private final Set<String> peers;
50 public Candidate(RaftActorContext context) {
53 peers = context.getPeerAddresses().keySet();
55 if(LOG.isDebugEnabled()) {
56 LOG.debug("Election:Candidate has following peers: {}", peers);
59 votesRequired = getMajorityVoteCount(peers.size());
62 scheduleElection(electionDuration());
65 @Override protected RaftActorBehavior handleAppendEntries(ActorRef sender,
66 AppendEntries appendEntries) {
68 if(LOG.isDebugEnabled()) {
69 LOG.debug(appendEntries.toString());
75 @Override protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender,
76 AppendEntriesReply appendEntriesReply) {
81 @Override protected RaftActorBehavior handleRequestVoteReply(ActorRef sender,
82 RequestVoteReply requestVoteReply) {
84 if (requestVoteReply.isVoteGranted()) {
88 if (voteCount >= votesRequired) {
89 return switchBehavior(new Leader(context));
95 @Override public RaftState state() {
96 return RaftState.Candidate;
100 public RaftActorBehavior handleMessage(ActorRef sender, Object originalMessage) {
102 Object message = fromSerializableMessage(originalMessage);
104 if (message instanceof RaftRPC) {
106 RaftRPC rpc = (RaftRPC) message;
108 if(LOG.isDebugEnabled()) {
109 LOG.debug("RaftRPC message received {} my term is {}", rpc, context.getTermInformation().getCurrentTerm());
112 // If RPC request or response contains term T > currentTerm:
113 // set currentTerm = T, convert to follower (§5.1)
114 // This applies to all RPC messages and responses
115 if (rpc.getTerm() > context.getTermInformation().getCurrentTerm()) {
116 context.getTermInformation().updateAndPersist(rpc.getTerm(), null);
118 return switchBehavior(new Follower(context));
122 if (message instanceof ElectionTimeout) {
123 if (votesRequired == 0) {
124 // If there are no peers then we should be a Leader
125 // We wait for the election timeout to occur before declare
126 // ourselves the leader. This gives enough time for a leader
127 // who we do not know about (as a peer)
128 // to send a message to the candidate
130 return switchBehavior(new Leader(context));
133 scheduleElection(electionDuration());
137 return super.handleMessage(sender, message);
141 private void startNewTerm() {
144 // set voteCount back to 1 (that is voting for self)
147 // Increment the election term and vote for self
148 long currentTerm = context.getTermInformation().getCurrentTerm();
149 context.getTermInformation().updateAndPersist(currentTerm + 1,
152 if(LOG.isDebugEnabled()) {
153 LOG.debug("Starting new term {}", (currentTerm + 1));
156 // Request for a vote
157 // TODO: Retry request for vote if replies do not arrive in a reasonable
158 // amount of time TBD
159 for (String peerId : peers) {
160 ActorSelection peerActor = context.getPeerActorSelection(peerId);
161 if(peerActor != null) {
162 peerActor.tell(new RequestVote(
163 context.getTermInformation().getCurrentTerm(),
165 context.getReplicatedLog().lastIndex(),
166 context.getReplicatedLog().lastTerm()),
175 @Override public void close() throws Exception {