X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-akka-raft%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fcluster%2Fraft%2Fbehaviors%2FCandidate.java;h=52ed26758ee26b6f9949fa1202f1a44628b82364;hb=a0b8be5ce48c0d1e0b573d1952211913c58d4935;hp=fb480a9433954a4afa238bbc6b9c0931488d2b7c;hpb=789431e2c0c76d9d00bdc7599a08036e3720f170;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 fb480a9433..52ed26758e 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
@@ -9,14 +9,22 @@
 package org.opendaylight.controller.cluster.raft.behaviors;
 
 import akka.actor.ActorRef;
+import akka.actor.ActorSelection;
+import java.util.ArrayList;
+import java.util.Collection;
+import org.opendaylight.controller.cluster.raft.PeerInfo;
 import org.opendaylight.controller.cluster.raft.RaftActorContext;
 import org.opendaylight.controller.cluster.raft.RaftState;
-
-import java.util.List;
+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;
 
 /**
  * The behavior of a RaftActor when it is in the CandidateState
- * <p>
+ * <p/>
  * Candidates (§5.2):
  * <ul>
  * <li> On conversion to candidate, start election:
@@ -33,15 +41,175 @@ import java.util.List;
  * </ul>
  */
 public class Candidate extends AbstractRaftActorBehavior {
-    private final List<String> peers;
 
-    public Candidate(RaftActorContext context, List<String> peers) {
-        super(context);
-        this.peers = peers;
+    private int voteCount;
+
+    private final int votesRequired;
+
+    private final Collection<String> votingPeers = new ArrayList<>();
+
+    public Candidate(RaftActorContext context) {
+        super(context, RaftState.Candidate);
+
+        for(PeerInfo peer: context.getPeers()) {
+            if(peer.isVoting()) {
+                votingPeers.add(peer.getId());
+            }
+        }
+
+        if(LOG.isDebugEnabled()) {
+            LOG.debug("{}: Election: Candidate has following voting peers: {}", logName(), votingPeers);
+        }
+
+        votesRequired = getMajorityVoteCount(votingPeers.size());
+
+        startNewTerm();
+
+        if(votingPeers.isEmpty()){
+            actor().tell(ElectionTimeout.INSTANCE, actor());
+        } else {
+            scheduleElection(electionDuration());
+        }
+    }
+
+    @Override
+    public final String getLeaderId() {
+        return null;
+    }
+
+    @Override
+    public final short getLeaderPayloadVersion() {
+        return -1;
+    }
+
+    @Override
+    protected RaftActorBehavior handleAppendEntries(ActorRef sender,
+        AppendEntries appendEntries) {
+
+        if(LOG.isDebugEnabled()) {
+            LOG.debug("{}: handleAppendEntries: {}", logName(), appendEntries);
+        }
+
+        // Some other candidate for the same term became a leader and sent us an append entry
+        if(currentTerm() == appendEntries.getTerm()){
+            LOG.debug("{}: New Leader sent an append entry to Candidate for term {} will switch to Follower",
+                    logName(), currentTerm());
+
+            return switchBehavior(new Follower(context));
+        }
+
+        return this;
+    }
+
+    @Override
+    protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender, AppendEntriesReply appendEntriesReply) {
+        return this;
+    }
+
+    @Override
+    protected RaftActorBehavior handleRequestVoteReply(ActorRef sender, RequestVoteReply requestVoteReply) {
+        LOG.debug("{}: handleRequestVoteReply: {}, current voteCount: {}", logName(), requestVoteReply, voteCount);
+
+        if (requestVoteReply.isVoteGranted()) {
+            voteCount++;
+        }
+
+        if (voteCount >= votesRequired) {
+            if(context.getCommitIndex() < context.getReplicatedLog().lastIndex()) {
+                LOG.debug("{}: Connmit index {} is behind last index {}", logName(), context.getCommitIndex(),
+                        context.getReplicatedLog().lastIndex());
+                return internalSwitchBehavior(RaftState.PreLeader);
+            } else {
+                return internalSwitchBehavior(RaftState.Leader);
+            }
+        }
+
+        return this;
+    }
+
+    @Override
+    public RaftActorBehavior handleMessage(ActorRef sender, Object message) {
+        if (message instanceof ElectionTimeout) {
+            LOG.debug("{}: Received ElectionTimeout", logName());
+
+            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;
+        }
+
+        if (message instanceof RaftRPC) {
+
+            RaftRPC rpc = (RaftRPC) message;
+
+            if(LOG.isDebugEnabled()) {
+                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()) {
+                context.getTermInformation().updateAndPersist(rpc.getTerm(), null);
+
+                // 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);
+            }
+        }
+
+        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();
+        long newTerm = currentTerm + 1;
+        context.getTermInformation().updateAndPersist(newTerm, context.getId());
+
+        LOG.debug("{}: Starting new 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 : votingPeers) {
+            ActorSelection peerActor = context.getPeerActorSelection(peerId);
+            if(peerActor != null) {
+                RequestVote requestVote = new RequestVote(
+                        context.getTermInformation().getCurrentTerm(),
+                        context.getId(),
+                        context.getReplicatedLog().lastIndex(),
+                        context.getReplicatedLog().lastTerm());
+
+                LOG.debug("{}: Sending {} to peer {}", logName(), requestVote, peerId);
+
+                peerActor.tell(requestVote, context.getActor());
+            }
+        }
     }
 
     @Override
-    public RaftState handleMessage(ActorRef sender, Object message) {
-        return RaftState.Candidate;
+    public void close() {
+        stopElection();
     }
 }