import akka.actor.ActorRef;
import akka.actor.Cancellable;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
import org.opendaylight.controller.cluster.raft.ClientRequestTracker;
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.SerializationUtils;
+import org.opendaylight.controller.cluster.raft.base.messages.ApplyJournalEntries;
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.RequestVote;
import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply;
+import org.slf4j.Logger;
import scala.concurrent.duration.FiniteDuration;
-import java.util.Random;
-import java.util.concurrent.TimeUnit;
-
/**
* Abstract class that represents the behavior of a RaftActor
* <p/>
*/
public abstract class AbstractRaftActorBehavior implements RaftActorBehavior {
+ protected static final ElectionTimeout ELECTION_TIMEOUT = new ElectionTimeout();
+
/**
* Information about the RaftActor whose behavior this class represents
*/
protected final RaftActorContext context;
+ /**
+ *
+ */
+ protected final Logger LOG;
+
/**
*
*/
*/
protected String leaderId = null;
+ private short leaderPayloadVersion = -1;
- protected AbstractRaftActorBehavior(RaftActorContext context) {
+ private long replicatedToAllIndex = -1;
+
+ private final String logName;
+
+ private final RaftState state;
+
+ protected AbstractRaftActorBehavior(RaftActorContext context, RaftState state) {
this.context = context;
+ this.state = state;
+ this.LOG = context.getLogger();
+
+ logName = String.format("%s (%s)", context.getId(), state);
+ }
+
+ @Override
+ public RaftState state() {
+ return state;
+ }
+
+ public String logName() {
+ return logName;
+ }
+
+ @Override
+ public void setReplicatedToAllIndex(long replicatedToAllIndex) {
+ this.replicatedToAllIndex = replicatedToAllIndex;
+ }
+
+ @Override
+ public long getReplicatedToAllIndex() {
+ return replicatedToAllIndex;
}
/**
*
* @param sender The actor that sent this message
* @param appendEntries The AppendEntries message
- * @return
+ * @return a new behavior if it was changed or the current behavior
*/
- protected abstract RaftState handleAppendEntries(ActorRef sender,
+ protected abstract RaftActorBehavior handleAppendEntries(ActorRef sender,
AppendEntries appendEntries);
*
* @param sender
* @param appendEntries
- * @return
+ * @return a new behavior if it was changed or the current behavior
*/
- protected RaftState appendEntries(ActorRef sender,
+ protected RaftActorBehavior appendEntries(ActorRef sender,
AppendEntries appendEntries) {
// 1. Reply false if term < currentTerm (§5.1)
if (appendEntries.getTerm() < currentTerm()) {
- context.getLogger().debug(
- "Cannot append entries because sender term " + appendEntries
- .getTerm() + " is less than " + currentTerm());
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: Cannot append entries because sender term {} is less than {}",
+ logName(), appendEntries.getTerm(), currentTerm());
+ }
+
sender.tell(
new AppendEntriesReply(context.getId(), currentTerm(), false,
- lastIndex(), lastTerm()), actor()
+ lastIndex(), lastTerm(), context.getPayloadVersion()), actor()
);
- return state();
+ return this;
}
*
* @param sender The actor that sent this message
* @param appendEntriesReply The AppendEntriesReply message
- * @return
+ * @return a new behavior if it was changed or the current behavior
*/
- protected abstract RaftState handleAppendEntriesReply(ActorRef sender,
+ protected abstract RaftActorBehavior handleAppendEntriesReply(ActorRef sender,
AppendEntriesReply appendEntriesReply);
/**
*
* @param sender
* @param requestVote
- * @return
+ * @return a new behavior if it was changed or the current behavior
*/
- protected RaftState requestVote(ActorRef sender,
- RequestVote requestVote) {
+ protected RaftActorBehavior requestVote(ActorRef sender, RequestVote requestVote) {
+
+ LOG.debug("{}: In requestVote: {}", logName(), requestVote);
+
+ boolean grantVote = canGrantVote(requestVote);
+
+ if(grantVote) {
+ context.getTermInformation().updateAndPersist(requestVote.getTerm(), requestVote.getCandidateId());
+ }
+
+ RequestVoteReply reply = new RequestVoteReply(currentTerm(), grantVote);
+
+ LOG.debug("{}: requestVote returning: {}", logName(), reply);
+
+ sender.tell(reply, actor());
+
+ return this;
+ }
+ protected boolean canGrantVote(RequestVote requestVote){
boolean grantVote = false;
// Reply false if term < currentTerm (§5.1)
// If votedFor is null or candidateId, and candidate’s log is at
// least as up-to-date as receiver’s log, grant vote (§5.2, §5.4)
} else if (votedFor() == null || votedFor()
- .equals(requestVote.getCandidateId())) {
+ .equals(requestVote.getCandidateId())) {
boolean candidateLatest = false;
if (requestVote.getLastLogTerm() > lastTerm()) {
candidateLatest = true;
} else if ((requestVote.getLastLogTerm() == lastTerm())
- && requestVote.getLastLogIndex() >= lastIndex()) {
+ && requestVote.getLastLogIndex() >= lastIndex()) {
candidateLatest = true;
}
if (candidateLatest) {
grantVote = true;
- context.getTermInformation().updateAndPersist(requestVote.getTerm(),
- requestVote.getCandidateId());
}
}
-
- sender.tell(new RequestVoteReply(currentTerm(), grantVote), actor());
-
- return state();
+ return grantVote;
}
/**
*
* @param sender The actor that sent this message
* @param requestVoteReply The RequestVoteReply message
- * @return
+ * @return a new behavior if it was changed or the current behavior
*/
- protected abstract RaftState handleRequestVoteReply(ActorRef sender,
+ protected abstract RaftActorBehavior handleRequestVoteReply(ActorRef sender,
RequestVoteReply requestVoteReply);
/**
- * Creates a random election duration
*
- * @return
+ * @return a random election duration
*/
protected FiniteDuration electionDuration() {
long variance = new Random().nextInt(context.getConfigParams().getElectionTimeVariance());
return context.getConfigParams().getElectionTimeOutInterval().$plus(
- new FiniteDuration(variance, TimeUnit.MILLISECONDS));
+ new FiniteDuration(variance, TimeUnit.MILLISECONDS));
}
/**
/**
* schedule a new election
*
- * @param interval
+ * @param interval the duration after which we should trigger a new election
*/
protected void scheduleElection(FiniteDuration interval) {
stopElection();
// message is sent to itself
electionCancel =
context.getActorSystem().scheduler().scheduleOnce(interval,
- context.getActor(), new ElectionTimeout(),
+ context.getActor(), ELECTION_TIMEOUT,
context.getActorSystem().dispatcher(), context.getActor());
}
/**
- * Get the current term
- * @return
+ * @return the current term
*/
protected long currentTerm() {
return context.getTermInformation().getCurrentTerm();
}
/**
- * Get the candidate for whom we voted in the current term
- * @return
+ * @return the candidate for whom we voted in the current term
*/
protected String votedFor() {
return context.getTermInformation().getVotedFor();
}
/**
- * Get the actor associated with this behavior
- * @return
+ * @return the actor associated with this behavior
*/
protected ActorRef actor() {
return context.getActor();
}
/**
- * Get the term from the last entry in the log
*
- * @return
+ * @return the term from the last entry in the log
*/
protected long lastTerm() {
return context.getReplicatedLog().lastTerm();
}
/**
- * Get the index from the last entry in the log
- *
- * @return
+ * @return the index from the last entry in the log
*/
protected long lastIndex() {
return context.getReplicatedLog().lastIndex();
}
/**
- * Find the client request tracker for a specific logIndex
- *
* @param logIndex
- * @return
+ * @return the client request tracker for the specified logIndex
*/
protected ClientRequestTracker findClientRequestTracker(long logIndex) {
return null;
}
/**
- * Find the log index from the previous to last entry in the log
+ * @param logIndex
+ * @return the client request tracker for the specified logIndex
+ */
+ protected ClientRequestTracker removeClientRequestTracker(long logIndex) {
+ return null;
+ }
+
+
+ /**
*
- * @return
+ * @return log index from the previous to last entry in the log
*/
protected long prevLogIndex(long index){
ReplicatedLogEntry prevEntry =
}
/**
- * Find the log term from the previous to last entry in the log
- * @return
+ * @return log term from the previous to last entry in the log
*/
protected long prevLogTerm(long index){
ReplicatedLogEntry prevEntry =
* @param index a log index that is known to be committed
*/
protected void applyLogToStateMachine(final long index) {
+ long newLastApplied = context.getLastApplied();
// Now maybe we apply to the state machine
for (long i = context.getLastApplied() + 1;
i < index + 1; i++) {
ActorRef clientActor = null;
String identifier = null;
- ClientRequestTracker tracker = findClientRequestTracker(i);
+ ClientRequestTracker tracker = removeClientRequestTracker(i);
if (tracker != null) {
clientActor = tracker.getClientActor();
context.getReplicatedLog().get(i);
if (replicatedLogEntry != null) {
+ // Send a local message to the local RaftActor (it's derived class to be
+ // specific to apply the log to it's index)
actor().tell(new ApplyState(clientActor, identifier,
replicatedLogEntry), actor());
+ newLastApplied = i;
} else {
- context.getLogger().error(
- "Missing index " + i + " from log. Cannot apply state.");
+ //if one index is not present in the log, no point in looping
+ // around as the rest wont be present either
+ LOG.warn(
+ "{}: Missing index {} from log. Cannot apply state. Ignoring {} to {}",
+ logName(), i, i, index);
+ break;
}
}
- // Send a local message to the local RaftActor (it's derived class to be
- // specific to apply the log to it's index)
- context.getLogger().info("Setting last applied to {}", index);
- context.setLastApplied(index);
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("{}: Setting last applied to {}", logName(), newLastApplied);
+ }
+ context.setLastApplied(newLastApplied);
+
+ // send a message to persist a ApplyLogEntries marker message into akka's persistent journal
+ // will be used during recovery
+ //in case if the above code throws an error and this message is not sent, it would be fine
+ // as the append entries received later would initiate add this message to the journal
+ actor().tell(new ApplyJournalEntries(context.getLastApplied()), actor());
}
protected Object fromSerializableMessage(Object serializable){
}
@Override
- public RaftState handleMessage(ActorRef sender, Object message) {
+ public RaftActorBehavior handleMessage(ActorRef sender, Object message) {
if (message instanceof AppendEntries) {
return appendEntries(sender, (AppendEntries) message);
} else if (message instanceof AppendEntriesReply) {
} else if (message instanceof RequestVoteReply) {
return handleRequestVoteReply(sender, (RequestVoteReply) message);
}
- return state();
+ return this;
}
@Override public String getLeaderId() {
return leaderId;
}
+
+ @Override
+ public short getLeaderPayloadVersion() {
+ return leaderPayloadVersion;
+ }
+
+ public void setLeaderPayloadVersion(short leaderPayloadVersion) {
+ this.leaderPayloadVersion = leaderPayloadVersion;
+ }
+
+ @Override
+ public RaftActorBehavior switchBehavior(RaftActorBehavior behavior) {
+ return internalSwitchBehavior(behavior);
+ }
+
+ protected RaftActorBehavior internalSwitchBehavior(RaftState newState) {
+ if(context.getRaftPolicy().automaticElectionsEnabled()){
+ return internalSwitchBehavior(newState.createBehavior(context));
+ }
+ return this;
+ }
+
+ private RaftActorBehavior internalSwitchBehavior(RaftActorBehavior newBehavior) {
+ LOG.info("{} :- Switching from behavior {} to {}", logName(), this.state(), newBehavior.state());
+ try {
+ close();
+ } catch (Exception e) {
+ LOG.error("{}: Failed to close behavior : {}", logName(), this.state(), e);
+ }
+ return newBehavior;
+ }
+
+
+ protected int getMajorityVoteCount(int numPeers) {
+ // Votes are required from a majority of the peers including self.
+ // The numMajority 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 numMajority would be for n
+ // peers
+ // 0 peers = 1 numMajority -: (0 + 1) / 2 + 1 = 1
+ // 2 peers = 2 numMajority -: (2 + 1) / 2 + 1 = 2
+ // 4 peers = 3 numMajority -: (4 + 1) / 2 + 1 = 3
+
+ int numMajority = 0;
+ if (numPeers > 0) {
+ int self = 1;
+ numMajority = (numPeers + self) / 2 + 1;
+ }
+ return numMajority;
+
+ }
+
+
+ /**
+ * Performs a snapshot with no capture on the replicated log.
+ * It clears the log from the supplied index or last-applied-1 which ever is minimum.
+ *
+ * @param snapshotCapturedIndex
+ */
+ protected void performSnapshotWithoutCapture(final long snapshotCapturedIndex) {
+ long actualIndex = context.getSnapshotManager().trimLog(snapshotCapturedIndex, this);
+
+ if(actualIndex != -1){
+ setReplicatedToAllIndex(actualIndex);
+ }
+ }
+
+ protected String getId(){
+ return context.getId();
+ }
+
}