package org.opendaylight.controller.cluster.raft.behaviors;
import akka.actor.ActorRef;
+import akka.actor.Cancellable;
+import com.google.common.base.Preconditions;
+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.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 org.opendaylight.controller.cluster.raft.persisted.ApplyJournalEntries;
+import org.slf4j.Logger;
+import scala.concurrent.duration.FiniteDuration;
/**
* Abstract class that represents the behavior of a RaftActor
* set currentTerm = T, convert to follower (§5.1)
*/
public abstract class AbstractRaftActorBehavior implements RaftActorBehavior {
-
/**
* Information about the RaftActor whose behavior this class represents
*/
protected final RaftActorContext context;
+ /**
+ *
+ */
+ protected final Logger LOG;
+
+ /**
+ *
+ */
+ private Cancellable electionCancel = null;
+
+ private long replicatedToAllIndex = -1;
+
+ private final String logName;
+
+ private final RaftState state;
+
+ AbstractRaftActorBehavior(final RaftActorContext context, final RaftState state) {
+ this.context = Preconditions.checkNotNull(context);
+ this.state = Preconditions.checkNotNull(state);
+ this.LOG = context.getLogger();
+
+ logName = String.format("%s (%s)", context.getId(), state);
+ }
+
+ public static RaftActorBehavior createBehavior(final RaftActorContext context, final RaftState state) {
+ switch (state) {
+ case Candidate:
+ return new Candidate(context);
+ case Follower:
+ return new Follower(context);
+ case IsolatedLeader:
+ return new IsolatedLeader(context);
+ case Leader:
+ return new Leader(context);
+ case PreLeader:
+ return new PreLeader(context);
+ default:
+ throw new IllegalArgumentException("Unhandled state " + state);
+ }
+ }
+
+ @Override
+ public final RaftState state() {
+ return state;
+ }
- protected AbstractRaftActorBehavior(RaftActorContext context) {
- this.context = context;
+ protected final 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
- * @param suggestedState The state that the RaftActor should be in based
- * on the base class's processing of the AppendEntries
- * message
- * @return
+ * @return a new behavior if it was changed or the current behavior
*/
- 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 a new behavior if it was changed or the current behavior
+ */
+ 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 {}",
+ logName(), appendEntries.getTerm(), currentTerm());
+ }
+
+ sender.tell(
+ new AppendEntriesReply(context.getId(), currentTerm(), false,
+ lastIndex(), lastTerm(), context.getPayloadVersion()), 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
+ * @return a new behavior if it was changed or the current behavior
*/
-
- 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
- * @return
+ * @param sender
+ * @param requestVote
+ * @return a new behavior if it was changed or the current behavior
*/
- protected abstract RaftState handleRequestVote(ActorRef sender,
- RequestVote requestVote, RaftState suggestedState);
+ 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 (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;
+ }
+ }
+ return grantVote;
+ }
/**
* 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
+ * @return a new behavior if it was changed or the current behavior
*/
+ protected abstract RaftActorBehavior handleRequestVoteReply(ActorRef sender,
+ RequestVoteReply requestVoteReply);
- protected abstract RaftState handleRequestVoteReply(ActorRef sender,
- RequestVoteReply requestVoteReply, RaftState suggestedState);
+ /**
+ *
+ * @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));
+ }
/**
- * @return The derived class should return the state that corresponds to
- * it's behavior
+ * stop the scheduled election
*/
- protected abstract RaftState state();
+ protected void stopElection() {
+ if (electionCancel != null && !electionCancel.isCancelled()) {
+ electionCancel.cancel();
+ }
+ }
- @Override
- public RaftState handleMessage(ActorRef sender, Object message) {
- RaftState raftState = state();
- if (message instanceof RaftRPC) {
- raftState = applyTerm((RaftRPC) message);
+ protected boolean canStartElection() {
+ return context.getRaftPolicy().automaticElectionsEnabled() && context.isVotingMember();
+ }
+
+ /**
+ * schedule a new election
+ *
+ * @param interval the duration after which we should trigger a new election
+ */
+ 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(),
+ ElectionTimeout.INSTANCE, context.getActorSystem().dispatcher(), context.getActor());
+ }
+
+ /**
+ * @return the current term
+ */
+ protected long currentTerm() {
+ return context.getTermInformation().getCurrentTerm();
+ }
+
+ /**
+ * @return the candidate for whom we voted in the current term
+ */
+ protected String votedFor() {
+ return context.getTermInformation().getVotedFor();
+ }
+
+ /**
+ * @return the actor associated with this behavior
+ */
+ protected ActorRef actor() {
+ return context.getActor();
+ }
+
+ /**
+ *
+ * @return the term from the last entry in the log
+ */
+ protected long lastTerm() {
+ return context.getReplicatedLog().lastTerm();
+ }
+
+ /**
+ * @return the index from the last entry in the log
+ */
+ protected long lastIndex() {
+ return context.getReplicatedLog().lastIndex();
+ }
+
+ /**
+ * @param logIndex
+ * @return the client request tracker for the specified logIndex
+ */
+ protected ClientRequestTracker removeClientRequestTracker(long logIndex) {
+ return null;
+ }
+
+ /**
+ *
+ * @return the log entry index for the given index or -1 if not found
+ */
+ protected long getLogEntryIndex(long index){
+ if(index == context.getReplicatedLog().getSnapshotIndex()){
+ return context.getReplicatedLog().getSnapshotIndex();
}
- if (message instanceof AppendEntries) {
- AppendEntries appendEntries = (AppendEntries) message;
- if (appendEntries.getLeaderCommit() > context.getLastApplied()
- .get()) {
- applyLogToStateMachine(appendEntries.getLeaderCommit());
+
+ ReplicatedLogEntry entry = context.getReplicatedLog().get(index);
+ if(entry != null){
+ return entry.getIndex();
+ }
+
+ return -1;
+ }
+
+ /**
+ * @return the log entry term for the given index or -1 if not found
+ */
+ protected long getLogEntryTerm(long index){
+ if(index == context.getReplicatedLog().getSnapshotIndex()){
+ return context.getReplicatedLog().getSnapshotTerm();
+ }
+
+ ReplicatedLogEntry entry = context.getReplicatedLog().get(index);
+ if(entry != null){
+ return entry.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++) {
+
+ 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)
+
+ final ApplyState msg;
+ final ClientRequestTracker tracker = removeClientRequestTracker(i);
+ if (tracker != null) {
+ msg = new ApplyState(tracker.getClientActor(), tracker.getIdentifier(), replicatedLogEntry);
+ } else {
+ msg = new ApplyState(null, null, replicatedLogEntry);
+ }
+
+ actor().tell(msg, 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.warn("{}: Missing index {} from log. Cannot apply state. Ignoring {} to {}",
+ logName(), i, i, index);
+ break;
}
- raftState = handleAppendEntries(sender, appendEntries, raftState);
+ }
+ 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());
+ }
+
+ @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);
+ } else {
+ return null;
+ }
+ }
+
+ @Override
+ public RaftActorBehavior switchBehavior(RaftActorBehavior behavior) {
+ return internalSwitchBehavior(behavior);
+ }
+
+ protected RaftActorBehavior internalSwitchBehavior(RaftState newState) {
+ return internalSwitchBehavior(createBehavior(context, newState));
+ }
+
+ protected RaftActorBehavior internalSwitchBehavior(RaftActorBehavior newBehavior) {
+ if(!context.getRaftPolicy().automaticElectionsEnabled()) {
+ return this;
+ }
+
+ 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 raftState;
+ return newBehavior;
}
- private RaftState applyTerm(RaftRPC rpc) {
- if (rpc.getTerm() > context.getTermInformation().getCurrentTerm()
- .get()) {
- context.getTermInformation().update(rpc.getTerm(), null);
- return RaftState.Follower;
+
+ 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);
+
+ if(actualIndex != -1){
+ setReplicatedToAllIndex(actualIndex);
}
- return state();
}
- private void applyLogToStateMachine(long index) {
- context.getLastApplied().set(index);
+ protected String getId(){
+ return context.getId();
}
}
Code Review / controller.git / blobdiff