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.ElectionTimeout;
+import org.opendaylight.controller.cluster.raft.base.messages.ApplySnapshot;
+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.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) {
+ AppendEntries appendEntries) {
+
+ if(appendEntries.getEntries() != null && appendEntries.getEntries().size() > 0) {
+ context.getLogger()
+ .info("Follower: Received {}", appendEntries.toString());
+ }
+
+ // TODO : Refactor this method into a bunch of smaller methods
+ // to make it easier to read. Before refactoring ensure tests
+ // cover the code properly
+
+ // 1. Reply false if term < currentTerm (§5.1)
+ // This is handled in the appendEntries method of the base class
// 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());
- if (lastIndex() > -1 && previousEntry != null
- && previousEntry.getTerm() != appendEntries
- .getPrevLogTerm()) {
+ boolean outOfSync = true;
+
+ // First check if the logs are in sync or not
+ if (lastIndex() == -1
+ && appendEntries.getPrevLogIndex() != -1) {
+
+ // The follower's log is out of sync because the leader does have
+ // an entry at prevLogIndex and this follower has no entries in
+ // it's log.
+
+ context.getLogger().debug(
+ "The followers log is empty and the senders prevLogIndex is {}",
+ appendEntries.getPrevLogIndex());
+
+ } else if (lastIndex() > -1
+ && appendEntries.getPrevLogIndex() != -1
+ && previousEntry == null) {
+
+ // The follower's log is out of sync because the Leader's
+ // prevLogIndex entry was not found in it's log
+
+ 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()) {
+
+ // The follower's log is out of sync because the Leader's
+ // prevLogIndex entry does exist in the follower's log but it has
+ // a different term in it
context.getLogger().debug(
- "Cannot append entries because previous entry term "
- + previousEntry.getTerm()
- + " is not equal to append entries prevLogTerm "
- + appendEntries.getPrevLogTerm());
+ "Cannot append entries because previous entry term {} is not equal to append entries prevLogTerm {}"
+ , previousEntry.getTerm()
+ , appendEntries.getPrevLogTerm());
+ } else {
+ outOfSync = false;
+ }
+ if (outOfSync) {
+ // We found that the log was out of sync so just send a negative
+ // reply and return
sender.tell(
new AppendEntriesReply(context.getId(), currentTerm(), false,
lastIndex(), lastTerm()), actor()
&& appendEntries.getEntries().size() > 0) {
context.getLogger().debug(
"Number of entries to be appended = " + appendEntries
- .getEntries().size());
+ .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) {
+
+ // Find the entry up until which the one that is not in the
+ // follower's log
for (int i = 0;
i < appendEntries.getEntries()
.size(); i++, addEntriesFrom++) {
break;
}
- if (newEntry != null && newEntry.getTerm() == matchEntry
+ if (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()
- .removeFrom(matchEntry.getIndex());
- break;
- }
+
+ context.getLogger().debug(
+ "Removing entries from log starting at "
+ + matchEntry.getIndex()
+ );
+
+ // Entries do not match so remove all subsequent entries
+ context.getReplicatedLog()
+ .removeFromAndPersist(matchEntry.getIndex());
+ break;
}
}
context.getLogger().debug(
"After cleanup entries to be added from = " + (addEntriesFrom
- + lastIndex()));
+ + 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)
- .toString());
+
+ context.getLogger().info(
+ "Append entry to log " + appendEntries.getEntries().get(
+ i).getData()
+ .toString()
+ );
context.getReplicatedLog()
.appendAndPersist(appendEntries.getEntries().get(i));
}
sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), true,
lastIndex(), lastTerm()), actor());
- return suggestedState;
+ 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 public RaftState state() {
return RaftState.Follower;
}
- @Override public RaftState handleMessage(ActorRef sender, Object message) {
- if(message instanceof ElectionTimeout){
+ @Override public RaftState handleMessage(ActorRef sender, Object originalMessage) {
+
+ Object message = fromSerializableMessage(originalMessage);
+
+ 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 installSnapshot = (InstallSnapshot) message;
+ actor().tell(new ApplySnapshot(installSnapshot.getData()), actor());
}
scheduleElection(electionDuration());
Code Review / controller.git / blobdiff