X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?p=controller.git;a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-akka-raft%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fcluster%2Fraft%2Fbehaviors%2FCandidate.java;h=13f5f1d7a49ac8388da4a2926590d0ba0edcdd57;hp=fb480a9433954a4afa238bbc6b9c0931488d2b7c;hb=00570ac6512cdeea8d3c1da85e4a2e118a6f925c;hpb=789431e2c0c76d9d00bdc7599a08036e3720f170

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..13f5f1d7a4 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 +9,23 @@
 package org.opendaylight.controller.cluster.raft.behaviors;
 
 import akka.actor.ActorRef;
+import akka.actor.ActorSelection;
 import org.opendaylight.controller.cluster.raft.RaftActorContext;
 import org.opendaylight.controller.cluster.raft.RaftState;
+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.RaftRPC;
+import org.opendaylight.controller.cluster.raft.messages.RequestVote;
+import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
 
 /**
  * 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 +42,136 @@ import java.util.List;
  * </ul>
  */
 public class Candidate extends AbstractRaftActorBehavior {
-    private final List<String> peers;
 
-    public Candidate(RaftActorContext context, List<String> peers) {
+    private final Map<String, ActorSelection> peerToActor = new HashMap<>();
+
+    private int voteCount;
+
+    private final int votesRequired;
+
+    public Candidate(RaftActorContext context) {
         super(context);
-        this.peers = peers;
+
+        Collection<String> peerPaths = context.getPeerAddresses().values();
+
+        for (String peerPath : peerPaths) {
+            peerToActor.put(peerPath,
+                context.actorSelection(peerPath));
+        }
+
+        context.getLogger().debug("Election:Candidate has following peers:"+peerToActor.keySet());
+        if(peerPaths.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 = peerPaths.size();
+            int self = 1;
+            votesRequired = (noOfPeers + self) / 2 + 1;
+        } else {
+            votesRequired = 0;
+        }
+
+        startNewTerm();
+        scheduleElection(electionDuration());
+    }
+
+    @Override protected RaftState handleAppendEntries(ActorRef sender,
+        AppendEntries appendEntries) {
+
+        return state();
+    }
+
+    @Override protected RaftState handleAppendEntriesReply(ActorRef sender,
+        AppendEntriesReply appendEntriesReply) {
+
+        return state();
+    }
+
+    @Override protected RaftState handleRequestVoteReply(ActorRef sender,
+        RequestVoteReply requestVoteReply) {
+
+        if (requestVoteReply.isVoteGranted()) {
+            voteCount++;
+        }
+
+        if (voteCount >= votesRequired) {
+            return RaftState.Leader;
+        }
+
+        return state();
+    }
+
+    @Override public RaftState state() {
+        return RaftState.Candidate;
     }
 
     @Override
     public RaftState handleMessage(ActorRef sender, Object message) {
-        return RaftState.Candidate;
+
+        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().update(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;
+            }
+            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().update(currentTerm + 1, context.getId());
+
+        context.getLogger().debug("Starting new term " + (currentTerm+1));
+
+        // Request for a vote
+        for (ActorSelection peerActor : peerToActor.values()) {
+            peerActor.tell(new RequestVote(
+                    context.getTermInformation().getCurrentTerm(),
+                    context.getId(),
+                    context.getReplicatedLog().lastIndex(),
+                    context.getReplicatedLog().lastTerm()),
+                context.getActor()
+            );
+        }
+
+
+    }
+
+    @Override public void close() throws Exception {
+        stopElection();
     }
 }