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 org.opendaylight.controller.cluster.raft.RaftActorContext;
13 import org.opendaylight.controller.cluster.raft.RaftState;
14 import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry;
15 import org.opendaylight.controller.cluster.raft.internal.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.RequestVoteReply;
21 * The behavior of a RaftActor in the Follower state
24 * <li> Respond to RPCs from candidates and leaders
25 * <li> If election timeout elapses without receiving AppendEntries
26 * RPC from current leader or granting vote to candidate:
27 * convert to candidate
31 public class Follower extends AbstractRaftActorBehavior {
32 public Follower(RaftActorContext context) {
35 scheduleElection(electionDuration());
38 @Override protected RaftState handleAppendEntries(ActorRef sender,
39 AppendEntries appendEntries, RaftState suggestedState) {
41 // If we got here then we do appear to be talking to the leader
42 leaderId = appendEntries.getLeaderId();
44 // 2. Reply false if log doesn’t contain an entry at prevLogIndex
45 // whose term matches prevLogTerm (§5.3)
46 ReplicatedLogEntry previousEntry = context.getReplicatedLog()
47 .get(appendEntries.getPrevLogIndex());
50 if (lastIndex() > -1 && previousEntry != null
51 && previousEntry.getTerm() != appendEntries
54 context.getLogger().debug(
55 "Cannot append entries because previous entry term "
56 + previousEntry.getTerm()
57 + " is not equal to append entries prevLogTerm "
58 + appendEntries.getPrevLogTerm());
61 new AppendEntriesReply(context.getId(), currentTerm(), false,
62 lastIndex(), lastTerm()), actor()
67 if (appendEntries.getEntries() != null
68 && appendEntries.getEntries().size() > 0) {
69 context.getLogger().debug(
70 "Number of entries to be appended = " + appendEntries
71 .getEntries().size());
73 // 3. If an existing entry conflicts with a new one (same index
74 // but different terms), delete the existing entry and all that
76 int addEntriesFrom = 0;
77 if (context.getReplicatedLog().size() > 0) {
79 i < appendEntries.getEntries()
80 .size(); i++, addEntriesFrom++) {
81 ReplicatedLogEntry matchEntry =
82 appendEntries.getEntries().get(i);
83 ReplicatedLogEntry newEntry = context.getReplicatedLog()
84 .get(matchEntry.getIndex());
86 if (newEntry == null) {
87 //newEntry not found in the log
91 if (newEntry != null && newEntry.getTerm() == matchEntry
95 if (newEntry != null && newEntry.getTerm() != matchEntry
97 context.getLogger().debug(
98 "Removing entries from log starting at "
99 + matchEntry.getIndex());
100 context.getReplicatedLog()
101 .removeFrom(matchEntry.getIndex());
107 context.getLogger().debug(
108 "After cleanup entries to be added from = " + (addEntriesFrom
111 // 4. Append any new entries not already in the log
112 for (int i = addEntriesFrom;
113 i < appendEntries.getEntries().size(); i++) {
114 context.getLogger().debug(
115 "Append entry to log " + appendEntries.getEntries().get(i)
117 context.getReplicatedLog()
118 .appendAndPersist(appendEntries.getEntries().get(i));
121 context.getLogger().debug(
122 "Log size is now " + context.getReplicatedLog().size());
126 // 5. If leaderCommit > commitIndex, set commitIndex =
127 // min(leaderCommit, index of last new entry)
129 long prevCommitIndex = context.getCommitIndex();
131 context.setCommitIndex(Math.min(appendEntries.getLeaderCommit(),
132 context.getReplicatedLog().lastIndex()));
134 if (prevCommitIndex != context.getCommitIndex()) {
136 .debug("Commit index set to " + context.getCommitIndex());
139 // If commitIndex > lastApplied: increment lastApplied, apply
140 // log[lastApplied] to state machine (§5.3)
141 if (appendEntries.getLeaderCommit() > context.getLastApplied()) {
142 applyLogToStateMachine(appendEntries.getLeaderCommit());
145 sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), true,
146 lastIndex(), lastTerm()), actor());
148 return suggestedState;
151 @Override protected RaftState handleAppendEntriesReply(ActorRef sender,
152 AppendEntriesReply appendEntriesReply, RaftState suggestedState) {
153 return suggestedState;
156 @Override protected RaftState handleRequestVoteReply(ActorRef sender,
157 RequestVoteReply requestVoteReply, RaftState suggestedState) {
158 return suggestedState;
161 @Override public RaftState state() {
162 return RaftState.Follower;
165 @Override public RaftState handleMessage(ActorRef sender, Object message) {
166 if(message instanceof ElectionTimeout){
167 return RaftState.Candidate;
170 scheduleElection(electionDuration());
172 return super.handleMessage(sender, message);
175 @Override public void close() throws Exception {