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;
14 import org.opendaylight.controller.cluster.raft.RaftActorContext;
15 import org.opendaylight.controller.cluster.raft.RaftState;
16 import org.opendaylight.controller.cluster.raft.base.messages.ElectionTimeout;
17 import org.opendaylight.controller.cluster.raft.messages.AppendEntries;
18 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
19 import org.opendaylight.controller.cluster.raft.messages.RaftRPC;
20 import org.opendaylight.controller.cluster.raft.messages.RequestVote;
21 import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply;
24 * The behavior of a RaftActor when it is in the CandidateState
28 * <li> On conversion to candidate, start election:
30 * <li> Increment currentTerm
32 * <li> Reset election timer
33 * <li> Send RequestVote RPCs to all other servers
35 * <li> If votes received from majority of servers: become leader
36 * <li> If AppendEntries RPC received from new leader: convert to
38 * <li> If election timeout elapses: start new election
41 public class Candidate extends AbstractRaftActorBehavior {
43 private int voteCount;
45 private final int votesRequired;
47 private final Set<String> peers;
49 public Candidate(RaftActorContext context) {
52 peers = context.getPeerAddresses().keySet();
54 if(LOG.isDebugEnabled()) {
55 LOG.debug("{}: Election: Candidate has following peers: {}", context.getId(), peers);
58 votesRequired = getMajorityVoteCount(peers.size());
61 scheduleElection(electionDuration());
64 @Override protected RaftActorBehavior handleAppendEntries(ActorRef sender,
65 AppendEntries appendEntries) {
67 if(LOG.isDebugEnabled()) {
68 LOG.debug("{}: handleAppendEntries: {}", context.getId(), appendEntries);
74 @Override protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender,
75 AppendEntriesReply appendEntriesReply) {
80 @Override protected RaftActorBehavior handleRequestVoteReply(ActorRef sender,
81 RequestVoteReply requestVoteReply) {
83 if (requestVoteReply.isVoteGranted()) {
87 if (voteCount >= votesRequired) {
88 return switchBehavior(new Leader(context));
94 @Override public RaftState state() {
95 return RaftState.Candidate;
99 public RaftActorBehavior handleMessage(ActorRef sender, Object originalMessage) {
101 Object message = fromSerializableMessage(originalMessage);
103 if (message instanceof RaftRPC) {
105 RaftRPC rpc = (RaftRPC) message;
107 if(LOG.isDebugEnabled()) {
108 LOG.debug("{}: RaftRPC message received {} my term is {}", context.getId(), rpc,
109 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 {}", context.getId(), (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 {