import akka.actor.ActorRef;
import org.opendaylight.controller.cluster.raft.RaftActorContext;
import org.opendaylight.controller.cluster.raft.RaftState;
+import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry;
+import org.opendaylight.controller.cluster.raft.internal.messages.ApplySnapshot;
import org.opendaylight.controller.cluster.raft.internal.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.InstallSnapshot;
+import org.opendaylight.controller.cluster.raft.messages.RaftRPC;
import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply;
/**
* The behavior of a RaftActor in the Follower state
- *
+ * <p/>
* <ul>
* <li> Respond to RPCs from candidates and leaders
* <li> If election timeout elapses without receiving AppendEntries
* RPC from current leader or granting vote to candidate:
* convert to candidate
* </ul>
- *
*/
public class Follower extends AbstractRaftActorBehavior {
public Follower(RaftActorContext context) {
}
@Override protected RaftState handleAppendEntries(ActorRef sender,
- AppendEntries appendEntries, RaftState suggestedState) {
- return suggestedState;
+ AppendEntries appendEntries) {
+
+ // If we got here then we do appear to be talking to the leader
+ leaderId = appendEntries.getLeaderId();
+
+ // 2. Reply false if log doesn’t contain an entry at prevLogIndex
+ // whose term matches prevLogTerm (§5.3)
+ ReplicatedLogEntry previousEntry = context.getReplicatedLog()
+ .get(appendEntries.getPrevLogIndex());
+
+
+ boolean noMatchingTerms = true;
+
+ if (lastIndex() == -1
+ && appendEntries.getPrevLogIndex() != -1) {
+
+ context.getLogger().debug(
+ "The followers log is empty and the senders prevLogIndex is {}",
+ appendEntries.getPrevLogIndex());
+
+ } else if (lastIndex() > -1
+ && appendEntries.getPrevLogIndex() != -1
+ && previousEntry == null) {
+
+ context.getLogger().debug(
+ "The log is not empty but the prevLogIndex {} was not found in it",
+ appendEntries.getPrevLogIndex());
+
+ } else if (lastIndex() > -1
+ && previousEntry != null
+ && previousEntry.getTerm()!= appendEntries.getPrevLogTerm()) {
+
+ context.getLogger().debug(
+ "Cannot append entries because previous entry term {} is not equal to append entries prevLogTerm {}"
+ , previousEntry.getTerm()
+ , appendEntries.getPrevLogTerm());
+ } else {
+ noMatchingTerms = false;
+ }
+
+ if (noMatchingTerms) {
+ sender.tell(
+ new AppendEntriesReply(context.getId(), currentTerm(), false,
+ lastIndex(), lastTerm()), actor()
+ );
+ return state();
+ }
+
+ if (appendEntries.getEntries() != null
+ && appendEntries.getEntries().size() > 0) {
+ context.getLogger().debug(
+ "Number of entries to be appended = " + appendEntries
+ .getEntries().size()
+ );
+
+ // 3. If an existing entry conflicts with a new one (same index
+ // but different terms), delete the existing entry and all that
+ // follow it (§5.3)
+ int addEntriesFrom = 0;
+ if (context.getReplicatedLog().size() > 0) {
+ for (int i = 0;
+ i < appendEntries.getEntries()
+ .size(); i++, addEntriesFrom++) {
+ ReplicatedLogEntry matchEntry =
+ appendEntries.getEntries().get(i);
+ ReplicatedLogEntry newEntry = context.getReplicatedLog()
+ .get(matchEntry.getIndex());
+
+ if (newEntry == null) {
+ //newEntry not found in the log
+ break;
+ }
+
+ if (newEntry != null && newEntry.getTerm() == matchEntry
+ .getTerm()) {
+ continue;
+ }
+ if (newEntry != null && newEntry.getTerm() != matchEntry
+ .getTerm()) {
+ context.getLogger().debug(
+ "Removing entries from log starting at "
+ + matchEntry.getIndex()
+ );
+ context.getReplicatedLog()
+ .removeFromAndPersist(matchEntry.getIndex());
+ break;
+ }
+ }
+ }
+
+ context.getLogger().debug(
+ "After cleanup entries to be added from = " + (addEntriesFrom
+ + lastIndex())
+ );
+
+ // 4. Append any new entries not already in the log
+ for (int i = addEntriesFrom;
+ i < appendEntries.getEntries().size(); i++) {
+ context.getLogger().debug(
+ "Append entry to log " + appendEntries.getEntries().get(i).getData()
+ .toString()
+ );
+ context.getReplicatedLog()
+ .appendAndPersist(appendEntries.getEntries().get(i));
+ }
+
+ context.getLogger().debug(
+ "Log size is now " + context.getReplicatedLog().size());
+ }
+
+
+ // 5. If leaderCommit > commitIndex, set commitIndex =
+ // min(leaderCommit, index of last new entry)
+
+ long prevCommitIndex = context.getCommitIndex();
+
+ context.setCommitIndex(Math.min(appendEntries.getLeaderCommit(),
+ context.getReplicatedLog().lastIndex()));
+
+ if (prevCommitIndex != context.getCommitIndex()) {
+ context.getLogger()
+ .debug("Commit index set to " + context.getCommitIndex());
+ }
+
+ // If commitIndex > lastApplied: increment lastApplied, apply
+ // log[lastApplied] to state machine (§5.3)
+ if (appendEntries.getLeaderCommit() > context.getLastApplied()) {
+ applyLogToStateMachine(appendEntries.getLeaderCommit());
+ }
+
+ sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), true,
+ lastIndex(), lastTerm()), actor());
+
+ return state();
}
@Override protected RaftState handleAppendEntriesReply(ActorRef sender,
- AppendEntriesReply appendEntriesReply, RaftState suggestedState) {
- return suggestedState;
+ AppendEntriesReply appendEntriesReply) {
+ return state();
}
@Override protected RaftState handleRequestVoteReply(ActorRef sender,
- RequestVoteReply requestVoteReply, RaftState suggestedState) {
- return suggestedState;
+ RequestVoteReply requestVoteReply) {
+ return state();
}
- @Override protected RaftState state() {
+ @Override public RaftState state() {
return RaftState.Follower;
}
@Override public RaftState handleMessage(ActorRef sender, Object message) {
- if(message instanceof ElectionTimeout){
+ 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);
+ }
+ }
+
+ if (message instanceof ElectionTimeout) {
return RaftState.Candidate;
+ } else if (message instanceof InstallSnapshot) {
+ InstallSnapshot snapshot = (InstallSnapshot) message;
+ actor().tell(new ApplySnapshot(snapshot), actor());
}
scheduleElection(electionDuration());
return super.handleMessage(sender, message);
}
+
+ @Override public void close() throws Exception {
+ stopElection();
+ }
}
Code Review / controller.git / blobdiff