BUG 2185 : Disable all internal switching of behavior
[controller.git] / opendaylight / md-sal / sal-akka-raft / src / main / java / org / opendaylight / controller / cluster / raft / behaviors / AbstractLeader.java
index 94c38f6108eabf62ef9e41a3f484a6e2f915129d..85f2f153ab3046d6541225c95d3863be3435b6b0 100644 (file)
@@ -26,6 +26,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
+import javax.annotation.Nullable;
 import org.opendaylight.controller.cluster.raft.ClientRequestTracker;
 import org.opendaylight.controller.cluster.raft.ClientRequestTrackerImpl;
 import org.opendaylight.controller.cluster.raft.FollowerLogInformation;
@@ -33,7 +34,7 @@ import org.opendaylight.controller.cluster.raft.FollowerLogInformationImpl;
 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.CaptureSnapshot;
+import org.opendaylight.controller.cluster.raft.Snapshot;
 import org.opendaylight.controller.cluster.raft.base.messages.Replicate;
 import org.opendaylight.controller.cluster.raft.base.messages.SendHeartBeat;
 import org.opendaylight.controller.cluster.raft.base.messages.SendInstallSnapshot;
@@ -89,17 +90,17 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
 
     protected final int minIsolatedLeaderPeerCount;
 
-    private Optional<ByteString> snapshot;
+    private Optional<SnapshotHolder> snapshot;
 
     public AbstractLeader(RaftActorContext context) {
-        super(context);
+        super(context, RaftState.Leader);
+
+        setLeaderPayloadVersion(context.getPayloadVersion());
 
         final Builder<String, FollowerLogInformation> ftlBuilder = ImmutableMap.builder();
         for (String followerId : context.getPeerAddresses().keySet()) {
             FollowerLogInformation followerLogInformation =
-                new FollowerLogInformationImpl(followerId,
-                    context.getCommitIndex(), -1,
-                    context.getConfigParams().getElectionTimeOutInterval());
+                new FollowerLogInformationImpl(followerId, -1, context);
 
             ftlBuilder.put(followerId, followerLogInformation);
         }
@@ -107,7 +108,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
 
         leaderId = context.getId();
 
-        LOG.debug("{}: Election: Leader has following peers: {}", context.getId(), getFollowerIds());
+        LOG.debug("{}: Election: Leader has following peers: {}", logName(), getFollowerIds());
 
         minReplicationCount = getMajorityVoteCount(getFollowerIds().size());
 
@@ -125,7 +126,10 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
         // Upon election: send initial empty AppendEntries RPCs
         // (heartbeat) to each server; repeat during idle periods to
         // prevent election timeouts (§5.2)
-        sendAppendEntries(0);
+        sendAppendEntries(0, false);
+
+        // It is important to schedule this heartbeat here
+        scheduleHeartBeat(context.getConfigParams().getHeartBeatInterval());
     }
 
     /**
@@ -133,26 +137,24 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
      *
      * @return Collection of follower IDs
      */
-    protected final Collection<String> getFollowerIds() {
+    public final Collection<String> getFollowerIds() {
         return followerToLog.keySet();
     }
 
-    private Optional<ByteString> getSnapshot() {
-        return snapshot;
-    }
-
     @VisibleForTesting
-    void setSnapshot(Optional<ByteString> snapshot) {
-        this.snapshot = snapshot;
+    void setSnapshot(@Nullable Snapshot snapshot) {
+        if(snapshot != null) {
+            this.snapshot = Optional.of(new SnapshotHolder(snapshot));
+        } else {
+            this.snapshot = Optional.absent();
+        }
     }
 
     @Override
     protected RaftActorBehavior handleAppendEntries(ActorRef sender,
         AppendEntries appendEntries) {
 
-        if(LOG.isDebugEnabled()) {
-            LOG.debug("{}: handleAppendEntries: {}", context.getId(), appendEntries);
-        }
+        LOG.debug("{}: handleAppendEntries: {}", logName(), appendEntries);
 
         return this;
     }
@@ -161,10 +163,8 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
     protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender,
         AppendEntriesReply appendEntriesReply) {
 
-        if(! appendEntriesReply.isSuccess()) {
-            if(LOG.isDebugEnabled()) {
-                LOG.debug("{}: handleAppendEntriesReply: {}", context.getId(), appendEntriesReply);
-            }
+        if(LOG.isTraceEnabled()) {
+            LOG.trace("{}: handleAppendEntriesReply: {}", logName(), appendEntriesReply);
         }
 
         // Update the FollowerLogInformation
@@ -173,26 +173,46 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
             followerToLog.get(followerId);
 
         if(followerLogInformation == null){
-            LOG.error("{}: handleAppendEntriesReply - unknown follower {}", context.getId(), followerId);
+            LOG.error("{}: handleAppendEntriesReply - unknown follower {}", logName(), followerId);
             return this;
         }
 
+        if(followerLogInformation.timeSinceLastActivity() >
+                context.getConfigParams().getElectionTimeOutInterval().toMillis()) {
+            LOG.warn("{} : handleAppendEntriesReply delayed beyond election timeout, " +
+                            "appendEntriesReply : {}, timeSinceLastActivity : {}, lastApplied : {}, commitIndex : {}",
+                    logName(), appendEntriesReply, followerLogInformation.timeSinceLastActivity(),
+                    context.getLastApplied(), context.getCommitIndex());
+        }
+
         followerLogInformation.markFollowerActive();
+        followerLogInformation.setPayloadVersion(appendEntriesReply.getPayloadVersion());
 
+        boolean updated = false;
         if (appendEntriesReply.isSuccess()) {
-            followerLogInformation
-                .setMatchIndex(appendEntriesReply.getLogLastIndex());
-            followerLogInformation
-                .setNextIndex(appendEntriesReply.getLogLastIndex() + 1);
+            updated = updateFollowerLogInformation(followerLogInformation, appendEntriesReply);
         } else {
+            LOG.debug("{}: handleAppendEntriesReply: received unsuccessful reply: {}", logName(), appendEntriesReply);
+
+            long followerLastLogIndex = appendEntriesReply.getLogLastIndex();
+            ReplicatedLogEntry followersLastLogEntry = context.getReplicatedLog().get(followerLastLogIndex);
+            if(followerLastLogIndex < 0 || (followersLastLogEntry != null &&
+                    followersLastLogEntry.getTerm() == appendEntriesReply.getLogLastTerm())) {
+                // The follower's log is empty or the last entry is present in the leader's journal
+                // and the terms match so the follower is just behind the leader's journal from
+                // the last snapshot, if any. We'll catch up the follower quickly by starting at the
+                // follower's last log index.
+
+                updated = updateFollowerLogInformation(followerLogInformation, appendEntriesReply);
+            } else {
+                // TODO: When we find that the follower is out of sync with the
+                // Leader we simply decrement that followers next index by 1.
+                // Would it be possible to do better than this? The RAFT spec
+                // does not explicitly deal with it but may be something for us to
+                // think about.
 
-            // TODO: When we find that the follower is out of sync with the
-            // Leader we simply decrement that followers next index by 1.
-            // Would it be possible to do better than this? The RAFT spec
-            // does not explicitly deal with it but may be something for us to
-            // think about
-
-            followerLogInformation.decrNextIndex();
+                followerLogInformation.decrNextIndex();
+            }
         }
 
         // Now figure out if this reply warrants a change in the commitIndex
@@ -221,18 +241,36 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
 
         // Apply the change to the state machine
         if (context.getCommitIndex() > context.getLastApplied()) {
+            if(LOG.isDebugEnabled()) {
+                LOG.debug("{}: handleAppendEntriesReply from {}: applying to log - commitIndex: {}, lastAppliedIndex: {}",
+                        logName(), followerId, context.getCommitIndex(), context.getLastApplied());
+            }
+
             applyLogToStateMachine(context.getCommitIndex());
         }
 
-        if (!context.isSnapshotCaptureInitiated()) {
+        if (!context.getSnapshotManager().isCapturing()) {
             purgeInMemoryLog();
         }
 
         //Send the next log entry immediately, if possible, no need to wait for heartbeat to trigger that event
-        sendUpdatesToFollower(followerId, followerLogInformation, false);
+        sendUpdatesToFollower(followerId, followerLogInformation, false, !updated);
         return this;
     }
 
+    private boolean updateFollowerLogInformation(FollowerLogInformation followerLogInformation,
+            AppendEntriesReply appendEntriesReply) {
+        boolean updated = followerLogInformation.setMatchIndex(appendEntriesReply.getLogLastIndex());
+        updated = followerLogInformation.setNextIndex(appendEntriesReply.getLogLastIndex() + 1) || updated;
+
+        if(updated && LOG.isDebugEnabled()) {
+            LOG.debug("{}: handleAppendEntriesReply - FollowerLogInformation for {} updated: matchIndex: {}, nextIndex: {}",
+                    logName(), followerLogInformation.getId(), followerLogInformation.getMatchIndex(),
+                    followerLogInformation.getNextIndex());
+        }
+        return updated;
+    }
+
     private void purgeInMemoryLog() {
         //find the lowest index across followers which has been replicated to all.
         // lastApplied if there are no followers, so that we keep clearing the log for single-node
@@ -276,10 +314,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
         return this;
     }
 
-    @Override
-    public RaftState state() {
-        return RaftState.Leader;
-    }
+    protected void beforeSendHeartbeat(){}
 
     @Override
     public RaftActorBehavior handleMessage(ActorRef sender, Object originalMessage) {
@@ -293,46 +328,47 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
             // set currentTerm = T, convert to follower (§5.1)
             // This applies to all RPC messages and responses
             if (rpc.getTerm() > context.getTermInformation().getCurrentTerm()) {
-                LOG.debug("{}: Term {} in \"{}\" message is greater than leader's term {}", context.getId(),
-                        rpc.getTerm(), rpc, context.getTermInformation().getCurrentTerm());
+                LOG.debug("{}: Term {} in \"{}\" message is greater than leader's term {} - switching to Follower",
+                        logName(), rpc.getTerm(), rpc, context.getTermInformation().getCurrentTerm());
 
                 context.getTermInformation().updateAndPersist(rpc.getTerm(), null);
 
-                return switchBehavior(new Follower(context));
+                return internalSwitchBehavior(RaftState.Follower);
             }
         }
 
-        try {
-            if (message instanceof SendHeartBeat) {
-                sendHeartBeat();
-                return this;
+        if (message instanceof SendHeartBeat) {
+            beforeSendHeartbeat();
+            sendHeartBeat();
+            scheduleHeartBeat(context.getConfigParams().getHeartBeatInterval());
+            return this;
 
-            } else if(message instanceof SendInstallSnapshot) {
-                // received from RaftActor
-                setSnapshot(Optional.of(((SendInstallSnapshot) message).getSnapshot()));
-                sendInstallSnapshot();
+        } else if(message instanceof SendInstallSnapshot) {
+            // received from RaftActor
+            setSnapshot(((SendInstallSnapshot) message).getSnapshot());
+            sendInstallSnapshot();
 
-            } else if (message instanceof Replicate) {
-                replicate((Replicate) message);
+        } else if (message instanceof Replicate) {
+            replicate((Replicate) message);
 
-            } else if (message instanceof InstallSnapshotReply){
-                handleInstallSnapshotReply((InstallSnapshotReply) message);
+        } else if (message instanceof InstallSnapshotReply){
+            handleInstallSnapshotReply((InstallSnapshotReply) message);
 
-            }
-        } finally {
-            scheduleHeartBeat(context.getConfigParams().getHeartBeatInterval());
         }
 
+
         return super.handleMessage(sender, message);
     }
 
     private void handleInstallSnapshotReply(InstallSnapshotReply reply) {
+        LOG.debug("{}: handleInstallSnapshotReply: {}", logName(), reply);
+
         String followerId = reply.getFollowerId();
         FollowerToSnapshot followerToSnapshot = mapFollowerToSnapshot.get(followerId);
 
         if (followerToSnapshot == null) {
             LOG.error("{}: FollowerId {} in InstallSnapshotReply not known to Leader",
-                    context.getId(), followerId);
+                    logName(), followerId);
             return;
         }
 
@@ -346,27 +382,25 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
                     //this was the last chunk reply
                     if(LOG.isDebugEnabled()) {
                         LOG.debug("{}: InstallSnapshotReply received, " +
-                                "last chunk received, Chunk:{}. Follower:{} Setting nextIndex:{}",
-                                context.getId(), reply.getChunkIndex(), followerId,
+                                "last chunk received, Chunk: {}. Follower: {} Setting nextIndex: {}",
+                                logName(), reply.getChunkIndex(), followerId,
                             context.getReplicatedLog().getSnapshotIndex() + 1
                         );
                     }
 
-                    followerLogInformation.setMatchIndex(
-                        context.getReplicatedLog().getSnapshotIndex());
-                    followerLogInformation.setNextIndex(
-                        context.getReplicatedLog().getSnapshotIndex() + 1);
+                    long followerMatchIndex = snapshot.get().getLastIncludedIndex();
+                    followerLogInformation.setMatchIndex(followerMatchIndex);
+                    followerLogInformation.setNextIndex(followerMatchIndex + 1);
                     mapFollowerToSnapshot.remove(followerId);
 
-                    if(LOG.isDebugEnabled()) {
-                        LOG.debug("{}: followerToLog.get(followerId).getNextIndex()=" +
-                                context.getId(), followerToLog.get(followerId).getNextIndex());
-                    }
+                    LOG.debug("{}: follower: {}, matchIndex set to {}, nextIndex set to {}",
+                                logName(), followerId, followerLogInformation.getMatchIndex(),
+                                followerLogInformation.getNextIndex());
 
                     if (mapFollowerToSnapshot.isEmpty()) {
                         // once there are no pending followers receiving snapshots
                         // we can remove snapshot from the memory
-                        setSnapshot(Optional.<ByteString>absent());
+                        setSnapshot(null);
                     }
                     wasLastChunk = true;
 
@@ -375,12 +409,15 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
                 }
             } else {
                 LOG.info("{}: InstallSnapshotReply received sending snapshot chunk failed, Will retry, Chunk: {}",
-                        context.getId(), reply.getChunkIndex());
+                        logName(), reply.getChunkIndex());
 
                 followerToSnapshot.markSendStatus(false);
             }
 
-            if (!wasLastChunk && followerToSnapshot.canSendNextChunk()) {
+            if (wasLastChunk && !context.getSnapshotManager().isCapturing()) {
+                // Since the follower is now caught up try to purge the log.
+                purgeInMemoryLog();
+            } else if (!wasLastChunk && followerToSnapshot.canSendNextChunk()) {
                 ActorSelection followerActor = context.getPeerActorSelection(followerId);
                 if(followerActor != null) {
                     sendSnapshotChunk(followerActor, followerId);
@@ -389,7 +426,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
 
         } else {
             LOG.error("{}: Chunk index {} in InstallSnapshotReply from follower {} does not match expected index {}",
-                    context.getId(), reply.getChunkIndex(), followerId,
+                    logName(), reply.getChunkIndex(), followerId,
                     followerToSnapshot.getChunkIndex());
 
             if(reply.getChunkIndex() == INVALID_CHUNK_INDEX){
@@ -403,9 +440,8 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
     private void replicate(Replicate replicate) {
         long logIndex = replicate.getReplicatedLogEntry().getIndex();
 
-        if(LOG.isDebugEnabled()) {
-            LOG.debug("{}: Replicate message {}", context.getId(), logIndex);
-        }
+        LOG.debug("{}: Replicate message: identifier: {}, logIndex: {}", logName(),
+                replicate.getIdentifier(), logIndex);
 
         // Create a tracker entry we will use this later to notify the
         // client actor
@@ -415,15 +451,20 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
                 logIndex)
         );
 
-        if (followerToLog.isEmpty()) {
+        boolean applyModificationToState = followerToLog.isEmpty()
+                || context.getRaftPolicy().applyModificationToStateBeforeConsensus();
+
+        if(applyModificationToState){
             context.setCommitIndex(logIndex);
             applyLogToStateMachine(logIndex);
-        } else {
-            sendAppendEntries(0);
+        }
+
+        if (!followerToLog.isEmpty()) {
+            sendAppendEntries(0, false);
         }
     }
 
-    private void sendAppendEntries(long timeSinceLastActivityInterval) {
+    private void sendAppendEntries(long timeSinceLastActivityInterval, boolean isHeartbeat) {
         // Send an AppendEntries to all followers
         for (Entry<String, FollowerLogInformation> e : followerToLog.entrySet()) {
             final String followerId = e.getKey();
@@ -431,7 +472,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
             // This checks helps not to send a repeat message to the follower
             if(!followerLogInformation.isFollowerActive() ||
                     followerLogInformation.timeSinceLastActivity() >= timeSinceLastActivityInterval) {
-                sendUpdatesToFollower(followerId, followerLogInformation, true);
+                sendUpdatesToFollower(followerId, followerLogInformation, true, isHeartbeat);
             }
         }
     }
@@ -444,12 +485,14 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
      */
 
     private void sendUpdatesToFollower(String followerId, FollowerLogInformation followerLogInformation,
-                                          boolean sendHeartbeat) {
+                                       boolean sendHeartbeat, boolean isHeartbeat) {
 
         ActorSelection followerActor = context.getPeerActorSelection(followerId);
         if (followerActor != null) {
             long followerNextIndex = followerLogInformation.getNextIndex();
             boolean isFollowerActive = followerLogInformation.isFollowerActive();
+            boolean sendAppendEntries = false;
+            List<ReplicatedLogEntry> entries = Collections.emptyList();
 
             if (mapFollowerToSnapshot.get(followerId) != null) {
                 // if install snapshot is in process , then sent next chunk if possible
@@ -457,47 +500,59 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
                     sendSnapshotChunk(followerActor, followerId);
                 } else if(sendHeartbeat) {
                     // we send a heartbeat even if we have not received a reply for the last chunk
-                    sendAppendEntriesToFollower(followerActor, followerLogInformation.getNextIndex(),
-                        Collections.<ReplicatedLogEntry>emptyList(), followerId);
+                    sendAppendEntries = true;
                 }
             } else {
                 long leaderLastIndex = context.getReplicatedLog().lastIndex();
                 long leaderSnapShotIndex = context.getReplicatedLog().getSnapshotIndex();
-                if (isFollowerActive &&
-                    context.getReplicatedLog().isPresent(followerNextIndex)) {
-                    // FIXME : Sending one entry at a time
-                    final List<ReplicatedLogEntry> entries = context.getReplicatedLog().getFrom(followerNextIndex, 1);
 
-                    sendAppendEntriesToFollower(followerActor, followerNextIndex, entries, followerId);
+                if((!isHeartbeat && LOG.isDebugEnabled()) || LOG.isTraceEnabled()) {
+                    LOG.debug("{}: Checking sendAppendEntries for follower {}: active: {}, followerNextIndex: {}, leaderLastIndex: {}, leaderSnapShotIndex: {}",
+                            logName(), followerId, isFollowerActive, followerNextIndex, leaderLastIndex, leaderSnapShotIndex);
+                }
+
+                if (isFollowerActive && context.getReplicatedLog().isPresent(followerNextIndex)) {
 
+                    LOG.debug("{}: sendAppendEntries: {} is present for follower {}", logName(),
+                            followerNextIndex, followerId);
+
+                    if(followerLogInformation.okToReplicate()) {
+                        // Try to send all the entries in the journal but not exceeding the max data size
+                        // for a single AppendEntries message.
+                        int maxEntries = (int) context.getReplicatedLog().size();
+                        entries = context.getReplicatedLog().getFrom(followerNextIndex, maxEntries,
+                                context.getConfigParams().getSnapshotChunkSize());
+                        sendAppendEntries = true;
+                    }
                 } else if (isFollowerActive && followerNextIndex >= 0 &&
-                    leaderLastIndex > followerNextIndex && !context.isSnapshotCaptureInitiated()) {
+                    leaderLastIndex > followerNextIndex && !context.getSnapshotManager().isCapturing()) {
                     // if the followers next index is not present in the leaders log, and
                     // if the follower is just not starting and if leader's index is more than followers index
                     // then snapshot should be sent
 
                     if (LOG.isDebugEnabled()) {
-                        LOG.debug("InitiateInstallSnapshot to follower:{}," +
-                                "follower-nextIndex:{}, leader-snapshot-index:{},  " +
-                                "leader-last-index:{}", followerId,
-                            followerNextIndex, leaderSnapShotIndex, leaderLastIndex
-                        );
+                        LOG.debug(String.format("%s: InitiateInstallSnapshot to follower: %s," +
+                                    "follower-nextIndex: %d, leader-snapshot-index: %d,  " +
+                                    "leader-last-index: %d", logName(), followerId,
+                                    followerNextIndex, leaderSnapShotIndex, leaderLastIndex));
                     }
 
                     // Send heartbeat to follower whenever install snapshot is initiated.
-                    sendAppendEntriesToFollower(followerActor, followerLogInformation.getNextIndex(),
-                            Collections.<ReplicatedLogEntry>emptyList(), followerId);
-
+                    sendAppendEntries = true;
                     initiateCaptureSnapshot(followerId, followerNextIndex);
 
                 } else if(sendHeartbeat) {
-                    //we send an AppendEntries, even if the follower is inactive
+                    // we send an AppendEntries, even if the follower is inactive
                     // in-order to update the followers timestamp, in case it becomes active again
-                    sendAppendEntriesToFollower(followerActor, followerLogInformation.getNextIndex(),
-                        Collections.<ReplicatedLogEntry>emptyList(), followerId);
+                    sendAppendEntries = true;
                 }
 
             }
+
+            if(sendAppendEntries) {
+                sendAppendEntriesToFollower(followerActor, followerNextIndex,
+                        entries, followerId);
+            }
         }
     }
 
@@ -506,10 +561,10 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
         AppendEntries appendEntries = new AppendEntries(currentTerm(), context.getId(),
             prevLogIndex(followerNextIndex),
             prevLogTerm(followerNextIndex), entries,
-            context.getCommitIndex(), super.getReplicatedToAllIndex());
+            context.getCommitIndex(), super.getReplicatedToAllIndex(), context.getPayloadVersion());
 
-        if(!entries.isEmpty()) {
-            LOG.debug("{}: Sending AppendEntries to follower {}: {}", context.getId(), followerId,
+        if(!entries.isEmpty() || LOG.isTraceEnabled()) {
+            LOG.debug("{}: Sending AppendEntries to follower {}: {}", logName(), followerId,
                     appendEntries);
         }
 
@@ -541,35 +596,17 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
                 final ActorSelection followerActor = context.getPeerActorSelection(followerId);
                 sendSnapshotChunk(followerActor, followerId);
 
-            } else if (!context.isSnapshotCaptureInitiated()) {
-
-                LOG.info("{}: Initiating Snapshot Capture to Install Snapshot, Leader:{}", context.getId(), getLeaderId());
-                ReplicatedLogEntry lastAppliedEntry = context.getReplicatedLog().get(context.getLastApplied());
-                long lastAppliedIndex = -1;
-                long lastAppliedTerm = -1;
-
-                if (lastAppliedEntry != null) {
-                    lastAppliedIndex = lastAppliedEntry.getIndex();
-                    lastAppliedTerm = lastAppliedEntry.getTerm();
-                } else if (context.getReplicatedLog().getSnapshotIndex() > -1) {
-                    lastAppliedIndex = context.getReplicatedLog().getSnapshotIndex();
-                    lastAppliedTerm = context.getReplicatedLog().getSnapshotTerm();
-                }
 
-                boolean isInstallSnapshotInitiated = true;
-                long replicatedToAllIndex = super.getReplicatedToAllIndex();
-                ReplicatedLogEntry replicatedToAllEntry = context.getReplicatedLog().get(replicatedToAllIndex);
-                actor().tell(new CaptureSnapshot(lastIndex(), lastTerm(), lastAppliedIndex, lastAppliedTerm,
-                    (replicatedToAllEntry != null ? replicatedToAllEntry.getIndex() : -1),
-                    (replicatedToAllEntry != null ? replicatedToAllEntry.getTerm() : -1),
-                    isInstallSnapshotInitiated), actor());
-                context.setSnapshotCaptureInitiated(true);
+            } else {
+                context.getSnapshotManager().captureToInstall(context.getReplicatedLog().last(),
+                        this.getReplicatedToAllIndex(), followerId);
             }
         }
     }
 
 
     private void sendInstallSnapshot() {
+        LOG.debug("{}: sendInstallSnapshot", logName());
         for (Entry<String, FollowerLogInformation> e : followerToLog.entrySet()) {
             ActorSelection followerActor = context.getPeerActorSelection(e.getKey());
 
@@ -591,7 +628,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
     private void sendSnapshotChunk(ActorSelection followerActor, String followerId) {
         try {
             if (snapshot.isPresent()) {
-                ByteString nextSnapshotChunk = getNextSnapshotChunk(followerId,snapshot.get());
+                ByteString nextSnapshotChunk = getNextSnapshotChunk(followerId, snapshot.get().getSnapshotBytes());
 
                 // Note: the previous call to getNextSnapshotChunk has the side-effect of adding
                 // followerId to the followerToSnapshot map.
@@ -599,8 +636,8 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
 
                 followerActor.tell(
                     new InstallSnapshot(currentTerm(), context.getId(),
-                        context.getReplicatedLog().getSnapshotIndex(),
-                        context.getReplicatedLog().getSnapshotTerm(),
+                        snapshot.get().getLastIncludedIndex(),
+                        snapshot.get().getLastIncludedTerm(),
                         nextSnapshotChunk,
                         followerToSnapshot.incrementChunkIndex(),
                         followerToSnapshot.getTotalChunks(),
@@ -608,13 +645,15 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
                     ).toSerializable(),
                     actor()
                 );
-                LOG.info("{}: InstallSnapshot sent to follower {}, Chunk: {}/{}",
-                        context.getId(), followerActor.path(),
-                        followerToSnapshot.getChunkIndex(),
-                        followerToSnapshot.getTotalChunks());
+
+                if(LOG.isDebugEnabled()) {
+                    LOG.debug("{}: InstallSnapshot sent to follower {}, Chunk: {}/{}",
+                            logName(), followerActor.path(), followerToSnapshot.getChunkIndex(),
+                            followerToSnapshot.getTotalChunks());
+                }
             }
         } catch (IOException e) {
-            LOG.error("{}: InstallSnapshot failed for Leader.", context.getId(), e);
+            LOG.error("{}: InstallSnapshot failed for Leader.", logName(), e);
         }
     }
 
@@ -629,15 +668,16 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
             mapFollowerToSnapshot.put(followerId, followerToSnapshot);
         }
         ByteString nextChunk = followerToSnapshot.getNextChunk();
-        if (LOG.isDebugEnabled()) {
-            LOG.debug("{}: Leader's snapshot nextChunk size:{}", context.getId(), nextChunk.size());
-        }
+
+        LOG.debug("{}: next snapshot chunk size for follower {}: {}", logName(), followerId, nextChunk.size());
+
         return nextChunk;
     }
 
     private void sendHeartBeat() {
         if (!followerToLog.isEmpty()) {
-            sendAppendEntries(context.getConfigParams().getHeartBeatInterval().toMillis());
+            LOG.trace("{}: Sending heartbeat", logName());
+            sendAppendEntries(context.getConfigParams().getHeartBeatInterval().toMillis(), true);
         }
     }
 
@@ -712,7 +752,7 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
                 ((size % context.getConfigParams().getSnapshotChunkSize()) > 0 ? 1 : 0);
             if(LOG.isDebugEnabled()) {
                 LOG.debug("{}: Snapshot {} bytes, total chunks to send:{}",
-                        context.getId(), size, totalChunks);
+                        logName(), size, totalChunks);
             }
             replyReceivedForOffset = -1;
             chunkIndex = AbstractLeader.FIRST_CHUNK_INDEX;
@@ -780,10 +820,10 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
                 }
             }
 
-            if(LOG.isDebugEnabled()) {
-                LOG.debug("{}: Next chunk: length={}, offset={},size={}", context.getId(),
+
+            LOG.debug("{}: Next chunk: length={}, offset={},size={}", logName(),
                     snapshotLength, start, size);
-            }
+
             ByteString substring = getSnapshotBytes().substring(start, start + size);
             nextChunkHashCode = substring.hashCode();
             return substring;
@@ -841,4 +881,28 @@ public abstract class AbstractLeader extends AbstractRaftActorBehavior {
     public int followerLogSize() {
         return followerToLog.size();
     }
+
+    private static class SnapshotHolder {
+        private final long lastIncludedTerm;
+        private final long lastIncludedIndex;
+        private final ByteString snapshotBytes;
+
+        SnapshotHolder(Snapshot snapshot) {
+            this.lastIncludedTerm = snapshot.getLastAppliedTerm();
+            this.lastIncludedIndex = snapshot.getLastAppliedIndex();
+            this.snapshotBytes = ByteString.copyFrom(snapshot.getState());
+        }
+
+        long getLastIncludedTerm() {
+            return lastIncludedTerm;
+        }
+
+        long getLastIncludedIndex() {
+            return lastIncludedIndex;
+        }
+
+        ByteString getSnapshotBytes() {
+            return snapshotBytes;
+        }
+    }
 }