package org.opendaylight.controller.cluster.raft.behaviors;
import akka.actor.ActorRef;
+import akka.actor.ActorSelection;
+import akka.actor.Cancellable;
+import akka.event.LoggingAdapter;
import com.google.common.base.Preconditions;
+import com.google.protobuf.ByteString;
+import org.opendaylight.controller.cluster.raft.ClientRequestTracker;
+import org.opendaylight.controller.cluster.raft.ClientRequestTrackerImpl;
+import org.opendaylight.controller.cluster.raft.FollowerLogInformation;
import org.opendaylight.controller.cluster.raft.FollowerLogInformationImpl;
import org.opendaylight.controller.cluster.raft.RaftActorContext;
-import org.opendaylight.controller.cluster.raft.RaftReplicator;
import org.opendaylight.controller.cluster.raft.RaftState;
-import org.opendaylight.controller.cluster.raft.internal.messages.SendHeartBeat;
+import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry;
+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;
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.InstallSnapshotReply;
+import org.opendaylight.controller.cluster.raft.messages.RaftRPC;
+import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply;
+import scala.concurrent.duration.FiniteDuration;
+import java.io.IOException;
+import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
/**
* The behavior of a RaftActor when it is in the Leader state
- * <p>
+ * <p/>
* Leaders:
* <ul>
* <li> Upon election: send initial empty AppendEntries RPCs
public class Leader extends AbstractRaftActorBehavior {
- private final Map<String, ActorRef> followerToReplicator = new HashMap<>();
+ protected final Map<String, FollowerLogInformation> followerToLog =
+ new HashMap();
+ protected final Map<String, FollowerToSnapshot> mapFollowerToSnapshot = new HashMap<>();
- public Leader(RaftActorContext context, List<String> followers){
+ private final Set<String> followers;
+
+ private Cancellable heartbeatSchedule = null;
+ private Cancellable appendEntriesSchedule = null;
+ private Cancellable installSnapshotSchedule = null;
+
+ private List<ClientRequestTracker> trackerList = new ArrayList<>();
+
+ private final int minReplicationCount;
+
+ private final LoggingAdapter LOG;
+
+ public Leader(RaftActorContext context) {
super(context);
- for(String follower : followers) {
+ LOG = context.getLogger();
- ActorRef replicator = context.actorOf(
- RaftReplicator.props(
- new FollowerLogInformationImpl(follower,
- new AtomicLong(0),
- new AtomicLong(0)),
- context.getActor()
- )
- );
+ if (lastIndex() >= 0) {
+ context.setCommitIndex(lastIndex());
+ }
+
+ followers = context.getPeerAddresses().keySet();
- // Create a replicator for each follower
- followerToReplicator.put(follower, replicator);
+ for (String followerId : followers) {
+ FollowerLogInformation followerLogInformation =
+ new FollowerLogInformationImpl(followerId,
+ new AtomicLong(lastIndex()),
+ new AtomicLong(-1));
+
+ followerToLog.put(followerId, followerLogInformation);
+ }
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("Election:Leader has following peers:" + followers);
}
+ if (followers.size() > 0) {
+ minReplicationCount = (followers.size() + 1) / 2 + 1;
+ } else {
+ minReplicationCount = 0;
+ }
+
+
+ // Immediately schedule a heartbeat
+ // Upon election: send initial empty AppendEntries RPCs
+ // (heartbeat) to each server; repeat during idle periods to
+ // prevent election timeouts (§5.2)
+ scheduleHeartBeat(new FiniteDuration(0, TimeUnit.SECONDS));
+
+ scheduleInstallSnapshotCheck(
+ new FiniteDuration(context.getConfigParams().getHeartBeatInterval().length() * 1000,
+ context.getConfigParams().getHeartBeatInterval().unit())
+ );
+
}
- @Override public RaftState handleMessage(ActorRef sender, Object message) {
- Preconditions.checkNotNull(sender, "sender should not be null");
+ @Override protected RaftState handleAppendEntries(ActorRef sender,
+ AppendEntries appendEntries) {
+
+ if(LOG.isDebugEnabled()) {
+ LOG.debug(appendEntries.toString());
+ }
+
+ return state();
+ }
+
+ @Override protected RaftState handleAppendEntriesReply(ActorRef sender,
+ AppendEntriesReply appendEntriesReply) {
+
+ if(! appendEntriesReply.isSuccess()) {
+ if(LOG.isDebugEnabled()) {
+ LOG.debug(appendEntriesReply.toString());
+ }
+ }
+
+ // Update the FollowerLogInformation
+ String followerId = appendEntriesReply.getFollowerId();
+ FollowerLogInformation followerLogInformation =
+ followerToLog.get(followerId);
- if(message instanceof SendHeartBeat) {
- sender.tell(new AppendEntries(
- context.getTermInformation().getCurrentTerm().get() , context.getId(),
- context.getReplicatedLog().last().getIndex(),
- context.getReplicatedLog().last().getTerm(),
- Collections.EMPTY_LIST), context.getActor());
+ if(followerLogInformation == null){
+ LOG.error("Unknown follower {}", followerId);
+ return state();
}
+
+ if (appendEntriesReply.isSuccess()) {
+ followerLogInformation
+ .setMatchIndex(appendEntriesReply.getLogLastIndex());
+ followerLogInformation
+ .setNextIndex(appendEntriesReply.getLogLastIndex() + 1);
+ } 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
+
+ followerLogInformation.decrNextIndex();
+ }
+
+ // Now figure out if this reply warrants a change in the commitIndex
+ // If there exists an N such that N > commitIndex, a majority
+ // of matchIndex[i] ≥ N, and log[N].term == currentTerm:
+ // set commitIndex = N (§5.3, §5.4).
+ for (long N = context.getCommitIndex() + 1; ; N++) {
+ int replicatedCount = 1;
+
+ for (FollowerLogInformation info : followerToLog.values()) {
+ if (info.getMatchIndex().get() >= N) {
+ replicatedCount++;
+ }
+ }
+
+ if (replicatedCount >= minReplicationCount) {
+ ReplicatedLogEntry replicatedLogEntry =
+ context.getReplicatedLog().get(N);
+ if (replicatedLogEntry != null
+ && replicatedLogEntry.getTerm()
+ == currentTerm()) {
+ context.setCommitIndex(N);
+ }
+ } else {
+ break;
+ }
+ }
+
+ // Apply the change to the state machine
+ if (context.getCommitIndex() > context.getLastApplied()) {
+ applyLogToStateMachine(context.getCommitIndex());
+ }
+
+ return state();
+ }
+
+ protected ClientRequestTracker removeClientRequestTracker(long logIndex) {
+
+ ClientRequestTracker toRemove = findClientRequestTracker(logIndex);
+ if(toRemove != null) {
+ trackerList.remove(toRemove);
+ }
+
+ return toRemove;
+ }
+
+ protected ClientRequestTracker findClientRequestTracker(long logIndex) {
+ for (ClientRequestTracker tracker : trackerList) {
+ if (tracker.getIndex() == logIndex) {
+ return tracker;
+ }
+ }
+
+ return null;
+ }
+
+ @Override protected RaftState handleRequestVoteReply(ActorRef sender,
+ RequestVoteReply requestVoteReply) {
+ return state();
+ }
+
+ @Override public RaftState state() {
return RaftState.Leader;
}
+
+ @Override public RaftState handleMessage(ActorRef sender, Object originalMessage) {
+ Preconditions.checkNotNull(sender, "sender should not be null");
+
+ 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);
+ return RaftState.Follower;
+ }
+ }
+
+ try {
+ if (message instanceof SendHeartBeat) {
+ return sendHeartBeat();
+ } else if(message instanceof SendInstallSnapshot) {
+ installSnapshotIfNeeded();
+ } else if (message instanceof Replicate) {
+ replicate((Replicate) message);
+ } else if (message instanceof InstallSnapshotReply){
+ handleInstallSnapshotReply(
+ (InstallSnapshotReply) message);
+ }
+ } finally {
+ scheduleHeartBeat(context.getConfigParams().getHeartBeatInterval());
+ }
+
+ return super.handleMessage(sender, message);
+ }
+
+ private void handleInstallSnapshotReply(InstallSnapshotReply reply) {
+ String followerId = reply.getFollowerId();
+ FollowerToSnapshot followerToSnapshot =
+ mapFollowerToSnapshot.get(followerId);
+
+ if (followerToSnapshot != null &&
+ followerToSnapshot.getChunkIndex() == reply.getChunkIndex()) {
+
+ if (reply.isSuccess()) {
+ if(followerToSnapshot.isLastChunk(reply.getChunkIndex())) {
+ //this was the last chunk reply
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("InstallSnapshotReply received, " +
+ "last chunk received, Chunk:{}. Follower:{} Setting nextIndex:{}",
+ reply.getChunkIndex(), followerId,
+ context.getReplicatedLog().getSnapshotIndex() + 1
+ );
+ }
+
+ FollowerLogInformation followerLogInformation =
+ followerToLog.get(followerId);
+ followerLogInformation.setMatchIndex(
+ context.getReplicatedLog().getSnapshotIndex());
+ followerLogInformation.setNextIndex(
+ context.getReplicatedLog().getSnapshotIndex() + 1);
+ mapFollowerToSnapshot.remove(followerId);
+
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("followerToLog.get(followerId).getNextIndex().get()=" +
+ followerToLog.get(followerId).getNextIndex().get());
+ }
+
+ } else {
+ followerToSnapshot.markSendStatus(true);
+ }
+ } else {
+ LOG.info("InstallSnapshotReply received, " +
+ "sending snapshot chunk failed, Will retry, Chunk:{}",
+ reply.getChunkIndex()
+ );
+ followerToSnapshot.markSendStatus(false);
+ }
+
+ } else {
+ LOG.error("ERROR!!" +
+ "FollowerId in InstallSnapshotReply not known to Leader" +
+ " or Chunk Index in InstallSnapshotReply not matching {} != {}",
+ followerToSnapshot.getChunkIndex(), reply.getChunkIndex()
+ );
+ }
+ }
+
+ private void replicate(Replicate replicate) {
+ long logIndex = replicate.getReplicatedLogEntry().getIndex();
+
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("Replicate message " + logIndex);
+ }
+
+ // Create a tracker entry we will use this later to notify the
+ // client actor
+ trackerList.add(
+ new ClientRequestTrackerImpl(replicate.getClientActor(),
+ replicate.getIdentifier(),
+ logIndex)
+ );
+
+ if (followers.size() == 0) {
+ context.setCommitIndex(logIndex);
+ applyLogToStateMachine(logIndex);
+ } else {
+ sendAppendEntries();
+ }
+ }
+
+ private void sendAppendEntries() {
+ // Send an AppendEntries to all followers
+ for (String followerId : followers) {
+ ActorSelection followerActor = context.getPeerActorSelection(followerId);
+
+ if (followerActor != null) {
+ FollowerLogInformation followerLogInformation = followerToLog.get(followerId);
+ long followerNextIndex = followerLogInformation.getNextIndex().get();
+ List<ReplicatedLogEntry> entries = Collections.emptyList();
+
+ if (mapFollowerToSnapshot.get(followerId) != null) {
+ if (mapFollowerToSnapshot.get(followerId).canSendNextChunk()) {
+ sendSnapshotChunk(followerActor, followerId);
+ }
+
+ } else {
+
+ if (context.getReplicatedLog().isPresent(followerNextIndex)) {
+ // FIXME : Sending one entry at a time
+ entries = context.getReplicatedLog().getFrom(followerNextIndex, 1);
+
+ followerActor.tell(
+ new AppendEntries(currentTerm(), context.getId(),
+ prevLogIndex(followerNextIndex),
+ prevLogTerm(followerNextIndex), entries,
+ context.getCommitIndex()).toSerializable(),
+ actor()
+ );
+
+ } else {
+ // if the followers next index is not present in the leaders log, then snapshot should be sent
+ long leaderSnapShotIndex = context.getReplicatedLog().getSnapshotIndex();
+ long leaderLastIndex = context.getReplicatedLog().lastIndex();
+ if (followerNextIndex >= 0 && leaderLastIndex >= followerNextIndex ) {
+ // if the follower is just not starting and leader's index
+ // is more than followers index
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("SendInstallSnapshot to follower:{}," +
+ "follower-nextIndex:{}, leader-snapshot-index:{}, " +
+ "leader-last-index:{}", followerId,
+ followerNextIndex, leaderSnapShotIndex, leaderLastIndex
+ );
+ }
+
+ actor().tell(new SendInstallSnapshot(), actor());
+ } else {
+ followerActor.tell(
+ new AppendEntries(currentTerm(), context.getId(),
+ prevLogIndex(followerNextIndex),
+ prevLogTerm(followerNextIndex), entries,
+ context.getCommitIndex()).toSerializable(),
+ actor()
+ );
+ }
+ }
+ }
+ }
+ }
+ }
+
+ /**
+ * An installSnapshot is scheduled at a interval that is a multiple of
+ * a HEARTBEAT_INTERVAL. This is to avoid the need to check for installing
+ * snapshots at every heartbeat.
+ */
+ private void installSnapshotIfNeeded(){
+ for (String followerId : followers) {
+ ActorSelection followerActor =
+ context.getPeerActorSelection(followerId);
+
+ if(followerActor != null) {
+ FollowerLogInformation followerLogInformation =
+ followerToLog.get(followerId);
+
+ long nextIndex = followerLogInformation.getNextIndex().get();
+
+ if (!context.getReplicatedLog().isPresent(nextIndex) &&
+ context.getReplicatedLog().isInSnapshot(nextIndex)) {
+ sendSnapshotChunk(followerActor, followerId);
+ }
+ }
+ }
+ }
+
+ /**
+ * Sends a snapshot chunk to a given follower
+ * InstallSnapshot should qualify as a heartbeat too.
+ */
+ private void sendSnapshotChunk(ActorSelection followerActor, String followerId) {
+ try {
+ followerActor.tell(
+ new InstallSnapshot(currentTerm(), context.getId(),
+ context.getReplicatedLog().getSnapshotIndex(),
+ context.getReplicatedLog().getSnapshotTerm(),
+ getNextSnapshotChunk(followerId,
+ context.getReplicatedLog().getSnapshot()),
+ mapFollowerToSnapshot.get(followerId).incrementChunkIndex(),
+ mapFollowerToSnapshot.get(followerId).getTotalChunks()
+ ).toSerializable(),
+ actor()
+ );
+ LOG.info("InstallSnapshot sent to follower {}, Chunk: {}/{}",
+ followerActor.path(), mapFollowerToSnapshot.get(followerId).getChunkIndex(),
+ mapFollowerToSnapshot.get(followerId).getTotalChunks());
+ } catch (IOException e) {
+ LOG.error("InstallSnapshot failed for Leader.", e);
+ }
+ }
+
+ /**
+ * Acccepts snaphot as ByteString, enters into map for future chunks
+ * creates and return a ByteString chunk
+ */
+ private ByteString getNextSnapshotChunk(String followerId, ByteString snapshotBytes) throws IOException {
+ FollowerToSnapshot followerToSnapshot = mapFollowerToSnapshot.get(followerId);
+ if (followerToSnapshot == null) {
+ followerToSnapshot = new FollowerToSnapshot(snapshotBytes);
+ mapFollowerToSnapshot.put(followerId, followerToSnapshot);
+ }
+ ByteString nextChunk = followerToSnapshot.getNextChunk();
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("Leader's snapshot nextChunk size:{}", nextChunk.size());
+ }
+
+ return nextChunk;
+ }
+
+ private RaftState sendHeartBeat() {
+ if (followers.size() > 0) {
+ sendAppendEntries();
+ }
+ return state();
+ }
+
+ private void stopHeartBeat() {
+ if (heartbeatSchedule != null && !heartbeatSchedule.isCancelled()) {
+ heartbeatSchedule.cancel();
+ }
+ }
+
+ private void stopInstallSnapshotSchedule() {
+ if (installSnapshotSchedule != null && !installSnapshotSchedule.isCancelled()) {
+ installSnapshotSchedule.cancel();
+ }
+ }
+
+ private void scheduleHeartBeat(FiniteDuration interval) {
+ if(followers.size() == 0){
+ // Optimization - do not bother scheduling a heartbeat as there are
+ // no followers
+ return;
+ }
+
+ stopHeartBeat();
+
+ // Schedule a heartbeat. When the scheduler triggers a SendHeartbeat
+ // message is sent to itself.
+ // Scheduling the heartbeat only once here because heartbeats do not
+ // need to be sent if there are other messages being sent to the remote
+ // actor.
+ heartbeatSchedule =
+ context.getActorSystem().scheduler().scheduleOnce(
+ interval,
+ context.getActor(), new SendHeartBeat(),
+ context.getActorSystem().dispatcher(), context.getActor());
+ }
+
+
+ private void scheduleInstallSnapshotCheck(FiniteDuration interval) {
+ if(followers.size() == 0){
+ // Optimization - do not bother scheduling a heartbeat as there are
+ // no followers
+ return;
+ }
+
+ stopInstallSnapshotSchedule();
+
+ // Schedule a message to send append entries to followers that can
+ // accept an append entries with some data in it
+ installSnapshotSchedule =
+ context.getActorSystem().scheduler().scheduleOnce(
+ interval,
+ context.getActor(), new SendInstallSnapshot(),
+ context.getActorSystem().dispatcher(), context.getActor());
+ }
+
+
+
+ @Override public void close() throws Exception {
+ stopHeartBeat();
+ }
+
+ @Override public String getLeaderId() {
+ return context.getId();
+ }
+
+ /**
+ * Encapsulates the snapshot bytestring and handles the logic of sending
+ * snapshot chunks
+ */
+ protected class FollowerToSnapshot {
+ private ByteString snapshotBytes;
+ private int offset = 0;
+ // the next snapshot chunk is sent only if the replyReceivedForOffset matches offset
+ private int replyReceivedForOffset;
+ // if replyStatus is false, the previous chunk is attempted
+ private boolean replyStatus = false;
+ private int chunkIndex;
+ private int totalChunks;
+
+ public FollowerToSnapshot(ByteString snapshotBytes) {
+ this.snapshotBytes = snapshotBytes;
+ replyReceivedForOffset = -1;
+ chunkIndex = 1;
+ int size = snapshotBytes.size();
+ totalChunks = ( size / context.getConfigParams().getSnapshotChunkSize()) +
+ ((size % context.getConfigParams().getSnapshotChunkSize()) > 0 ? 1 : 0);
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("Snapshot {} bytes, total chunks to send:{}",
+ size, totalChunks);
+ }
+ }
+
+ public ByteString getSnapshotBytes() {
+ return snapshotBytes;
+ }
+
+ public int incrementOffset() {
+ if(replyStatus) {
+ // if prev chunk failed, we would want to sent the same chunk again
+ offset = offset + context.getConfigParams().getSnapshotChunkSize();
+ }
+ return offset;
+ }
+
+ public int incrementChunkIndex() {
+ if (replyStatus) {
+ // if prev chunk failed, we would want to sent the same chunk again
+ chunkIndex = chunkIndex + 1;
+ }
+ return chunkIndex;
+ }
+
+ public int getChunkIndex() {
+ return chunkIndex;
+ }
+
+ public int getTotalChunks() {
+ return totalChunks;
+ }
+
+ public boolean canSendNextChunk() {
+ // we only send a false if a chunk is sent but we have not received a reply yet
+ return replyReceivedForOffset == offset;
+ }
+
+ public boolean isLastChunk(int chunkIndex) {
+ return totalChunks == chunkIndex;
+ }
+
+ public void markSendStatus(boolean success) {
+ if (success) {
+ // if the chunk sent was successful
+ replyReceivedForOffset = offset;
+ replyStatus = true;
+ } else {
+ // if the chunk sent was failure
+ replyReceivedForOffset = offset;
+ replyStatus = false;
+ }
+ }
+
+ public ByteString getNextChunk() {
+ int snapshotLength = getSnapshotBytes().size();
+ int start = incrementOffset();
+ int size = context.getConfigParams().getSnapshotChunkSize();
+ if (context.getConfigParams().getSnapshotChunkSize() > snapshotLength) {
+ size = snapshotLength;
+ } else {
+ if ((start + context.getConfigParams().getSnapshotChunkSize()) > snapshotLength) {
+ size = snapshotLength - start;
+ }
+ }
+
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("length={}, offset={},size={}",
+ snapshotLength, start, size);
+ }
+ return getSnapshotBytes().substring(start, start + size);
+
+ }
+ }
+
}
Code Review / controller.git / blobdiff