package org.opendaylight.controller.cluster.raft.behaviors;
import akka.actor.ActorRef;
+import akka.actor.Cancellable;
+import akka.event.LoggingAdapter;
+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.ApplyLogEntries;
+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.RaftRPC;
import org.opendaylight.controller.cluster.raft.messages.RequestVote;
import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply;
+import scala.concurrent.duration.FiniteDuration;
+
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
/**
* Abstract class that represents the behavior of a RaftActor
*/
protected final RaftActorContext context;
+ /**
+ *
+ */
+ protected final LoggingAdapter LOG;
+
+ /**
+ *
+ */
+ private Cancellable electionCancel = null;
+
+ /**
+ *
+ */
+ protected String leaderId = null;
+
protected AbstractRaftActorBehavior(RaftActorContext context) {
this.context = context;
+ this.LOG = context.getLogger();
}
/**
*
* @param sender The actor that sent this message
* @param appendEntries The AppendEntries message
- * @param suggestedState The state that the RaftActor should be in based
- * on the base class's processing of the AppendEntries
- * message
* @return
*/
- protected abstract RaftState handleAppendEntries(ActorRef sender,
- AppendEntries appendEntries, RaftState suggestedState);
+ protected abstract RaftActorBehavior handleAppendEntries(ActorRef sender,
+ AppendEntries appendEntries);
+
+
+ /**
+ * appendEntries first processes the AppendEntries message and then
+ * delegates handling to a specific behavior
+ *
+ * @param sender
+ * @param appendEntries
+ * @return
+ */
+ protected RaftActorBehavior appendEntries(ActorRef sender,
+ AppendEntries appendEntries) {
+
+ // 1. Reply false if term < currentTerm (§5.1)
+ if (appendEntries.getTerm() < currentTerm()) {
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("Cannot append entries because sender term {} is less than {}",
+ appendEntries.getTerm(), currentTerm());
+ }
+
+ sender.tell(
+ new AppendEntriesReply(context.getId(), currentTerm(), false,
+ lastIndex(), lastTerm()), actor()
+ );
+ return this;
+ }
+
+
+ return handleAppendEntries(sender, appendEntries);
+ }
/**
* Derived classes should not directly handle AppendEntriesReply messages it
*
* @param sender The actor that sent this message
* @param appendEntriesReply The AppendEntriesReply message
- * @param suggestedState The state that the RaftActor should be in based
- * on the base class's processing of the
- * AppendEntriesReply message
* @return
*/
-
- protected abstract RaftState handleAppendEntriesReply(ActorRef sender,
- AppendEntriesReply appendEntriesReply, RaftState suggestedState);
+ protected abstract RaftActorBehavior handleAppendEntriesReply(ActorRef sender,
+ AppendEntriesReply appendEntriesReply);
/**
- * Derived classes should not directly handle RequestVote messages it
- * should let the base class handle it first. Once the base class handles
- * the RequestVote message and does the common actions that are applicable
- * in all RaftState's it will delegate the handling of the RequestVote
- * message to the derived class to do more state specific handling by calling
- * this method
+ * requestVote handles the RequestVote message. This logic is common
+ * for all behaviors
*
- * @param sender The actor that sent this message
- * @param requestVote The RequestVote message
- * @param suggestedState The state that the RaftActor should be in based
- * on the base class's processing of the RequestVote
- * message
+ * @param sender
+ * @param requestVote
* @return
*/
- protected abstract RaftState handleRequestVote(ActorRef sender,
- RequestVote requestVote, RaftState suggestedState);
+ protected RaftActorBehavior requestVote(ActorRef sender,
+ RequestVote requestVote) {
+
+ if(LOG.isDebugEnabled()) {
+ LOG.debug(requestVote.toString());
+ }
+
+ boolean grantVote = false;
+
+ // Reply false if term < currentTerm (§5.1)
+ if (requestVote.getTerm() < currentTerm()) {
+ grantVote = false;
+
+ // 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())) {
+
+ boolean candidateLatest = false;
+
+ // From §5.4.1
+ // Raft determines which of two logs is more up-to-date
+ // by comparing the index and term of the last entries in the
+ // logs. If the logs have last entries with different terms, then
+ // the log with the later term is more up-to-date. If the logs
+ // end with the same term, then whichever log is longer is
+ // more up-to-date.
+ if (requestVote.getLastLogTerm() > lastTerm()) {
+ candidateLatest = true;
+ } else if ((requestVote.getLastLogTerm() == lastTerm())
+ && requestVote.getLastLogIndex() >= lastIndex()) {
+ candidateLatest = true;
+ }
+
+ if (candidateLatest) {
+ grantVote = true;
+ context.getTermInformation().updateAndPersist(requestVote.getTerm(),
+ requestVote.getCandidateId());
+ }
+ }
+
+ sender.tell(new RequestVoteReply(currentTerm(), grantVote), actor());
+
+ return this;
+ }
/**
* Derived classes should not directly handle RequestVoteReply messages it
*
* @param sender The actor that sent this message
* @param requestVoteReply The RequestVoteReply message
- * @param suggestedState The state that the RaftActor should be in based
- * on the base class's processing of the RequestVote
- * message
* @return
*/
+ protected abstract RaftActorBehavior handleRequestVoteReply(ActorRef sender,
+ RequestVoteReply requestVoteReply);
+
+ /**
+ * Creates a random election duration
+ *
+ * @return
+ */
+ protected FiniteDuration electionDuration() {
+ long variance = new Random().nextInt(context.getConfigParams().getElectionTimeVariance());
+ return context.getConfigParams().getElectionTimeOutInterval().$plus(
+ new FiniteDuration(variance, TimeUnit.MILLISECONDS));
+ }
- protected abstract RaftState handleRequestVoteReply(ActorRef sender,
- RequestVoteReply requestVoteReply, RaftState suggestedState);
+ /**
+ * stop the scheduled election
+ */
+ protected void stopElection() {
+ if (electionCancel != null && !electionCancel.isCancelled()) {
+ electionCancel.cancel();
+ }
+ }
/**
- * @return The derived class should return the state that corresponds to
- * it's behavior
+ * schedule a new election
+ *
+ * @param interval
*/
- protected abstract RaftState state();
+ protected void scheduleElection(FiniteDuration interval) {
+ stopElection();
- @Override
- public RaftState handleMessage(ActorRef sender, Object message) {
- RaftState raftState = state();
- if (message instanceof RaftRPC) {
- raftState = applyTerm((RaftRPC) message);
+ // Schedule an election. When the scheduler triggers an ElectionTimeout
+ // message is sent to itself
+ electionCancel =
+ context.getActorSystem().scheduler().scheduleOnce(interval,
+ context.getActor(), new ElectionTimeout(),
+ context.getActorSystem().dispatcher(), context.getActor());
+ }
+
+ /**
+ * Get the current term
+ * @return
+ */
+ protected long currentTerm() {
+ return context.getTermInformation().getCurrentTerm();
+ }
+
+ /**
+ * Get the candidate for whom we voted in the current term
+ * @return
+ */
+ protected String votedFor() {
+ return context.getTermInformation().getVotedFor();
+ }
+
+ /**
+ * Get the actor associated with this behavior
+ * @return
+ */
+ protected ActorRef actor() {
+ return context.getActor();
+ }
+
+ /**
+ * Get the term from the last entry in the log
+ *
+ * @return
+ */
+ protected long lastTerm() {
+ return context.getReplicatedLog().lastTerm();
+ }
+
+ /**
+ * Get the index from the last entry in the log
+ *
+ * @return
+ */
+ protected long lastIndex() {
+ return context.getReplicatedLog().lastIndex();
+ }
+
+ /**
+ * Find the client request tracker for a specific logIndex
+ *
+ * @param logIndex
+ * @return
+ */
+ protected ClientRequestTracker findClientRequestTracker(long logIndex) {
+ return null;
+ }
+
+ /**
+ * Find the client request tracker for a specific logIndex
+ *
+ * @param logIndex
+ * @return
+ */
+ protected ClientRequestTracker removeClientRequestTracker(long logIndex) {
+ return null;
+ }
+
+
+ /**
+ * Find the log index from the previous to last entry in the log
+ *
+ * @return
+ */
+ protected long prevLogIndex(long index){
+ ReplicatedLogEntry prevEntry =
+ context.getReplicatedLog().get(index - 1);
+ if (prevEntry != null) {
+ return prevEntry.getIndex();
}
- if (message instanceof AppendEntries) {
- AppendEntries appendEntries = (AppendEntries) message;
- if (appendEntries.getLeaderCommit() > context.getLastApplied()
- .get()) {
- applyLogToStateMachine(appendEntries.getLeaderCommit());
+ return -1;
+ }
+
+ /**
+ * Find the log term from the previous to last entry in the log
+ * @return
+ */
+ protected long prevLogTerm(long index){
+ ReplicatedLogEntry prevEntry =
+ context.getReplicatedLog().get(index - 1);
+ if (prevEntry != null) {
+ return prevEntry.getTerm();
+ }
+ return -1;
+ }
+
+ /**
+ * Apply the provided index to the state machine
+ *
+ * @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 = removeClientRequestTracker(i);
+
+ if (tracker != null) {
+ clientActor = tracker.getClientActor();
+ identifier = tracker.getIdentifier();
+ }
+ ReplicatedLogEntry replicatedLogEntry =
+ 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 {
+ //if one index is not present in the log, no point in looping
+ // around as the rest wont be present either
+ LOG.warning(
+ "Missing index {} from log. Cannot apply state. Ignoring {} to {}", i, i, index);
+ break;
}
- raftState = handleAppendEntries(sender, appendEntries, raftState);
+ }
+ if(LOG.isDebugEnabled()) {
+ LOG.debug("Setting last applied to {}", 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 ApplyLogEntries((int) context.getLastApplied()), actor());
+ }
+
+ protected Object fromSerializableMessage(Object serializable){
+ return SerializationUtils.fromSerializable(serializable);
+ }
+
+ @Override
+ public RaftActorBehavior handleMessage(ActorRef sender, Object message) {
+ if (message instanceof AppendEntries) {
+ return appendEntries(sender, (AppendEntries) message);
} else if (message instanceof AppendEntriesReply) {
- raftState =
- handleAppendEntriesReply(sender, (AppendEntriesReply) message,
- raftState);
+ return handleAppendEntriesReply(sender, (AppendEntriesReply) message);
} else if (message instanceof RequestVote) {
- raftState =
- handleRequestVote(sender, (RequestVote) message, raftState);
+ return requestVote(sender, (RequestVote) message);
} else if (message instanceof RequestVoteReply) {
- raftState =
- handleRequestVoteReply(sender, (RequestVoteReply) message,
- raftState);
+ return handleRequestVoteReply(sender, (RequestVoteReply) message);
}
- return raftState;
+ return this;
}
- private RaftState applyTerm(RaftRPC rpc) {
- if (rpc.getTerm() > context.getTermInformation().getCurrentTerm()
- .get()) {
- context.getTermInformation().update(rpc.getTerm(), null);
- return RaftState.Follower;
- }
- return state();
+ @Override public String getLeaderId() {
+ return leaderId;
}
- private void applyLogToStateMachine(long index) {
- context.getLastApplied().set(index);
+ protected RaftActorBehavior switchBehavior(RaftActorBehavior behavior) {
+ LOG.info("Switching from behavior {} to {}", this.state(), behavior.state());
+ try {
+ close();
+ } catch (Exception e) {
+ LOG.error(e, "Failed to close behavior : {}", this.state());
+ }
+
+ return behavior;
}
}
Code Review / controller.git / blobdiff