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.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.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
- * <p>
+ * <p/>
* All Servers:
* <ul>
* <li> If commitIndex > lastApplied: increment lastApplied, apply
*/
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();
+ }
+
+ /**
+ * Derived classes should not directly handle AppendEntries messages it
+ * should let the base class handle it first. Once the base class handles
+ * the AppendEntries message and does the common actions that are applicable
+ * in all RaftState's it will delegate the handling of the AppendEntries
+ * message to the derived class to do more state specific handling by calling
+ * this method
+ *
+ * @param sender The actor that sent this message
+ * @param appendEntries The AppendEntries message
+ * @return
+ */
+ 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
+ * should let the base class handle it first. Once the base class handles
+ * the AppendEntriesReply message and does the common actions that are
+ * applicable in all RaftState's it will delegate the handling of the
+ * AppendEntriesReply message to the derived class to do more state specific
+ * handling by calling this method
+ *
+ * @param sender The actor that sent this message
+ * @param appendEntriesReply The AppendEntriesReply message
+ * @return
+ */
+ protected abstract RaftActorBehavior handleAppendEntriesReply(ActorRef sender,
+ AppendEntriesReply appendEntriesReply);
+
+ /**
+ * requestVote handles the RequestVote message. This logic is common
+ * for all behaviors
+ *
+ * @param sender
+ * @param requestVote
+ * @return
+ */
+ 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
+ * should let the base class handle it first. Once the base class handles
+ * the RequestVoteReply message and does the common actions that are
+ * applicable in all RaftState's it will delegate the handling of the
+ * RequestVoteReply message to the derived class to do more state specific
+ * handling by calling this method
+ *
+ * @param sender The actor that sent this message
+ * @param requestVoteReply The RequestVoteReply 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));
+ }
+
+ /**
+ * stop the scheduled election
+ */
+ protected void stopElection() {
+ if (electionCancel != null && !electionCancel.isCancelled()) {
+ electionCancel.cancel();
+ }
+ }
+
+ /**
+ * schedule a new election
+ *
+ * @param interval
+ */
+ protected void scheduleElection(FiniteDuration interval) {
+ stopElection();
+
+ // 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();
+ }
+ 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;
+ }
+ }
+ 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) {
+ return handleAppendEntriesReply(sender, (AppendEntriesReply) message);
+ } else if (message instanceof RequestVote) {
+ return requestVote(sender, (RequestVote) message);
+ } else if (message instanceof RequestVoteReply) {
+ return handleRequestVoteReply(sender, (RequestVoteReply) message);
+ }
+ return this;
+ }
+
+ @Override public String getLeaderId() {
+ return leaderId;
+ }
+
+ 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