X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;ds=sidebyside;f=opendaylight%2Fmd-sal%2Fsal-akka-raft%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fcluster%2Fraft%2Fbehaviors%2FCandidate.java;h=77f7a06c49dffe75557e6544e2deba03f16f5614;hb=HEAD;hp=bb1927ef231949bd320d0cf060d6a9a8018829bb;hpb=886fe1a50077d9dc9c4c36f938fc7c86317cb149;p=controller.git
diff --git a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Candidate.java b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Candidate.java
index bb1927ef23..77f7a06c49 100644
--- a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Candidate.java
+++ b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Candidate.java
@@ -5,25 +5,28 @@
* terms of the Eclipse Public License v1.0 which accompanies this distribution,
* and is available at http://www.eclipse.org/legal/epl-v10.html
*/
-
package org.opendaylight.controller.cluster.raft.behaviors;
import akka.actor.ActorRef;
import akka.actor.ActorSelection;
+import com.google.common.collect.ImmutableList;
+import org.opendaylight.controller.cluster.raft.PeerInfo;
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.base.messages.ApplyState;
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.RaftRPC;
import org.opendaylight.controller.cluster.raft.messages.RequestVote;
import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply;
-
-import java.util.Set;
+import scala.concurrent.duration.FiniteDuration;
/**
- * The behavior of a RaftActor when it is in the CandidateState
- *
+ * The behavior of a RaftActor when it is in the Candidate raft state.
+ *
+ *
* Candidates (§5.2):
*
* - On conversion to candidate, start election:
@@ -39,148 +42,176 @@ import java.util.Set;
*
- If election timeout elapses: start new election
*
*/
-public class Candidate extends AbstractRaftActorBehavior {
+public final class Candidate extends AbstractRaftActorBehavior {
+ private final ImmutableList votingPeers;
+ private final int votesRequired;
private int voteCount;
- private final int votesRequired;
+ public Candidate(final RaftActorContext context) {
+ super(context, RaftState.Candidate);
+
+ votingPeers = context.getPeers().stream()
+ .filter(PeerInfo::isVoting)
+ .map(PeerInfo::getId)
+ .collect(ImmutableList.toImmutableList());
+
+ log.debug("{}: Election: Candidate has following voting peers: {}", logName(), votingPeers);
+
+ votesRequired = getMajorityVoteCount(votingPeers.size());
- private final Set peers;
-
- public Candidate(RaftActorContext context) {
- super(context);
-
- peers = context.getPeerAddresses().keySet();
-
- context.getLogger().debug("Election:Candidate has following peers:"+ peers);
-
- if(peers.size() > 0) {
- // Votes are required from a majority of the peers including self.
- // The votesRequired field therefore stores a calculated value
- // of the number of votes required for this candidate to win an
- // election based on it's known peers.
- // If a peer was added during normal operation and raft replicas
- // came to know about them then the new peer would also need to be
- // taken into consideration when calculating this value.
- // Here are some examples for what the votesRequired would be for n
- // peers
- // 0 peers = 1 votesRequired (0 + 1) / 2 + 1 = 1
- // 2 peers = 2 votesRequired (2 + 1) / 2 + 1 = 2
- // 4 peers = 3 votesRequired (4 + 1) / 2 + 1 = 3
- int noOfPeers = peers.size();
- int self = 1;
- votesRequired = (noOfPeers + self) / 2 + 1;
+ startNewTerm();
+
+ if (votingPeers.isEmpty()) {
+ actor().tell(ElectionTimeout.INSTANCE, actor());
} else {
- votesRequired = 0;
+ scheduleElection(electionDuration());
}
+ }
- startNewTerm();
- scheduleElection(electionDuration());
+ @Override
+ public String getLeaderId() {
+ return null;
+ }
+
+ @Override
+ public short getLeaderPayloadVersion() {
+ return -1;
}
- @Override protected RaftState handleAppendEntries(ActorRef sender,
- AppendEntries appendEntries) {
+ @Override
+ protected RaftActorBehavior handleAppendEntries(final ActorRef sender, final AppendEntries appendEntries) {
+
+ log.debug("{}: handleAppendEntries: {}", logName(), appendEntries);
- context.getLogger().debug(appendEntries.toString());
+ // Some other candidate for the same term became a leader and sent us an append entry
+ if (currentTerm() == appendEntries.getTerm()) {
+ log.info("{}: New Leader {} sent an AppendEntries to Candidate for term {} - will switch to Follower",
+ logName(), appendEntries.getLeaderId(), currentTerm());
- return state();
- }
+ return switchBehavior(new Follower(context));
+ }
- @Override protected RaftState handleAppendEntriesReply(ActorRef sender,
- AppendEntriesReply appendEntriesReply) {
+ return this;
+ }
- return state();
+ @Override
+ protected RaftActorBehavior handleAppendEntriesReply(final ActorRef sender,
+ final AppendEntriesReply appendEntriesReply) {
+ return this;
}
- @Override protected RaftState handleRequestVoteReply(ActorRef sender,
- RequestVoteReply requestVoteReply) {
+ @Override
+ protected RaftActorBehavior handleRequestVoteReply(final ActorRef sender, final RequestVoteReply requestVoteReply) {
+ log.debug("{}: handleRequestVoteReply: {}, current voteCount: {}", logName(), requestVoteReply, voteCount);
if (requestVoteReply.isVoteGranted()) {
voteCount++;
}
if (voteCount >= votesRequired) {
- return RaftState.Leader;
+ if (context.getLastApplied() < context.getReplicatedLog().lastIndex()) {
+ log.info("{}: LastApplied index {} is behind last index {} - switching to PreLeader",
+ logName(), context.getLastApplied(), context.getReplicatedLog().lastIndex());
+ return internalSwitchBehavior(RaftState.PreLeader);
+ } else {
+ return internalSwitchBehavior(RaftState.Leader);
+ }
}
- return state();
+ return this;
}
- @Override public RaftState state() {
- return RaftState.Candidate;
+ @Override
+ protected FiniteDuration electionDuration() {
+ return super.electionDuration().$div(context.getConfigParams().getCandidateElectionTimeoutDivisor());
}
+
@Override
- public RaftState handleMessage(ActorRef sender, Object originalMessage) {
+ ApplyState getApplyStateFor(final ReplicatedLogEntry entry) {
+ throw new IllegalStateException("A candidate should never attempt to apply " + entry);
+ }
- Object message = fromSerializableMessage(originalMessage);
+ @Override
+ public RaftActorBehavior handleMessage(final ActorRef sender, final Object message) {
+ if (message instanceof ElectionTimeout) {
+ log.debug("{}: Received ElectionTimeout", logName());
- if (message instanceof RaftRPC) {
+ if (votesRequired == 0) {
+ // If there are no peers then we should be a Leader
+ // We wait for the election timeout to occur before declare
+ // ourselves the leader. This gives enough time for a leader
+ // who we do not know about (as a peer)
+ // to send a message to the candidate
+
+ return internalSwitchBehavior(RaftState.Leader);
+ }
+
+ startNewTerm();
+ scheduleElection(electionDuration());
+ return this;
+ }
- RaftRPC rpc = (RaftRPC) message;
+ if (message instanceof RaftRPC rpc) {
- context.getLogger().debug("RaftRPC message received {} my term is {}", rpc.toString(), context.getTermInformation().getCurrentTerm());
+ log.debug("{}: RaftRPC message received {}, my term is {}", logName(), rpc,
+ context.getTermInformation().getCurrentTerm());
// 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()) {
+ log.info("{}: Term {} in \"{}\" message is greater than Candidate's term {} - switching to Follower",
+ logName(), rpc.getTerm(), rpc, context.getTermInformation().getCurrentTerm());
+
context.getTermInformation().updateAndPersist(rpc.getTerm(), null);
- return RaftState.Follower;
- }
- }
- if (message instanceof ElectionTimeout) {
- if (votesRequired == 0) {
- // If there are no peers then we should be a Leader
- // We wait for the election timeout to occur before declare
- // ourselves the leader. This gives enough time for a leader
- // who we do not know about (as a peer)
- // to send a message to the candidate
- return RaftState.Leader;
+ // The raft paper does not say whether or not a Candidate can/should process a RequestVote in
+ // this case but doing so gains quicker convergence when the sender's log is more up-to-date.
+ if (message instanceof RequestVote) {
+ super.handleMessage(sender, message);
+ }
+
+ return internalSwitchBehavior(RaftState.Follower);
}
- startNewTerm();
- scheduleElection(electionDuration());
- return state();
}
return super.handleMessage(sender, message);
}
-
private void startNewTerm() {
-
-
// set voteCount back to 1 (that is voting for self)
voteCount = 1;
// Increment the election term and vote for self
long currentTerm = context.getTermInformation().getCurrentTerm();
- context.getTermInformation().updateAndPersist(currentTerm + 1,
- context.getId());
+ long newTerm = currentTerm + 1;
+ context.getTermInformation().updateAndPersist(newTerm, context.getId());
- context.getLogger().debug("Starting new term " + (currentTerm + 1));
+ log.info("{}: Starting new election term {}", logName(), newTerm);
// Request for a vote
// TODO: Retry request for vote if replies do not arrive in a reasonable
// amount of time TBD
- for (String peerId : peers) {
+ for (String peerId : votingPeers) {
ActorSelection peerActor = context.getPeerActorSelection(peerId);
- if(peerActor != null) {
- peerActor.tell(new RequestVote(
+ if (peerActor != null) {
+ RequestVote requestVote = new RequestVote(
context.getTermInformation().getCurrentTerm(),
context.getId(),
context.getReplicatedLog().lastIndex(),
- context.getReplicatedLog().lastTerm()),
- context.getActor()
- );
- }
- }
+ context.getReplicatedLog().lastTerm());
+ log.debug("{}: Sending {} to peer {}", logName(), requestVote, peerId);
+ peerActor.tell(requestVote, context.getActor());
+ }
+ }
}
- @Override public void close() throws Exception {
+ @Override
+ public void close() {
stopElection();
}
}