import akka.actor.ActorRef;
import akka.actor.Cancellable;
+import com.google.common.base.Preconditions;
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+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.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.opendaylight.controller.cluster.raft.persisted.ApplyJournalEntries;
+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/>
- * All Servers:
- * <ul>
- * <li> If commitIndex > lastApplied: increment lastApplied, apply
- * log[lastApplied] to state machine (§5.3)
- * <li> If RPC request or response contains term T > currentTerm:
- * set currentTerm = T, convert to follower (§5.1)
+ * Abstract class that provides common code for a RaftActor behavior.
*/
public abstract class AbstractRaftActorBehavior implements RaftActorBehavior {
-
/**
- * Information about the RaftActor whose behavior this class represents
+ * Information about the RaftActor whose behavior this class represents.
*/
protected final RaftActorContext context;
/**
- *
+ * Used for message logging.
+ */
+ @SuppressFBWarnings("SLF4J_LOGGER_SHOULD_BE_PRIVATE")
+ protected final Logger log;
+
+ /**
+ * Prepended to log messages to provide appropriate context.
+ */
+ private final String logName;
+
+ /**
+ * The RaftState corresponding to his behavior.
+ */
+ private final RaftState state;
+
+ /**
+ * Used to cancel a scheduled election.
*/
private Cancellable electionCancel = null;
/**
- *
+ * The index of the last log entry that has been replicated to all raft peers.
*/
- protected String leaderId = null;
+ private long replicatedToAllIndex = -1;
+
+ 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 final String logName() {
+ return logName;
+ }
+
+ @Override
+ public void setReplicatedToAllIndex(final long replicatedToAllIndex) {
+ this.replicatedToAllIndex = replicatedToAllIndex;
+ }
- protected AbstractRaftActorBehavior(RaftActorContext context) {
- this.context = context;
+ @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);
-
/**
- * appendEntries first processes the AppendEntries message and then
- * delegates handling to a specific behavior
+ * Handles the common logic for the AppendEntries message and delegates handling to the derived class.
*
- * @param sender
- * @param appendEntries
- * @return
+ * @param sender the ActorRef that sent the message
+ * @param appendEntries the message
+ * @return a new behavior if it was changed or the current behavior
*/
- protected RaftState appendEntries(ActorRef sender,
- AppendEntries appendEntries) {
+ protected RaftActorBehavior appendEntries(final ActorRef sender, final 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());
- sender.tell(
- new AppendEntriesReply(context.getId(), currentTerm(), false,
- lastIndex(), lastTerm()), actor()
- );
- return state();
+ log.info("{}: Cannot append entries because sender's term {} is less than {}", logName(),
+ appendEntries.getTerm(), currentTerm());
+
+ sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex(), lastTerm(),
+ context.getPayloadVersion(), false, false, appendEntries.getLeaderRaftVersion()), actor());
+ 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);
/**
- * requestVote handles the RequestVote message. This logic is common
- * for all behaviors
+ * Handles the logic for the RequestVote message that is common for all behaviors.
*
- * @param sender
- * @param requestVote
- * @return
+ * @param sender the ActorRef that sent the message
+ * @param requestVote the message
+ * @return a new behavior if it was changed or the current behavior
*/
- protected RaftState requestVote(ActorRef sender,
- RequestVote requestVote) {
+ protected RaftActorBehavior requestVote(final ActorRef sender, final RequestVote requestVote) {
+
+ log.debug("{}: In requestVote: {} - currentTerm: {}, votedFor: {}, lastIndex: {}, lastTerm: {}", logName(),
+ requestVote, currentTerm(), votedFor(), lastIndex(), lastTerm());
+
+ 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(final 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;
// more up-to-date.
if (requestVote.getLastLogTerm() > lastTerm()) {
candidateLatest = true;
- } else if ((requestVote.getLastLogTerm() == lastTerm())
- && requestVote.getLastLogIndex() >= lastIndex()) {
+ } 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 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
+ * Returns a duration for election with an additional variance for randomness.
*
- * @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));
}
/**
- * stop the scheduled election
+ * Stops the currently scheduled election.
*/
protected void stopElection() {
if (electionCancel != null && !electionCancel.isCancelled()) {
}
}
+ protected boolean canStartElection() {
+ return context.getRaftPolicy().automaticElectionsEnabled() && context.isVotingMember();
+ }
+
/**
- * schedule a new election
+ * Schedule a new election.
*
- * @param interval
+ * @param interval the duration after which we should trigger a new election
*/
- protected void scheduleElection(FiniteDuration interval) {
+ protected void scheduleElection(final 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());
+ // 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());
}
/**
- * Get the current term
- * @return
+ * Returns the current election term.
+ *
+ * @return the current term
*/
protected long currentTerm() {
return context.getTermInformation().getCurrentTerm();
}
/**
- * Get the candidate for whom we voted in the current term
- * @return
+ * Returns the id of the candidate that this server voted for in current term.
+ *
+ * @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
+ * Returns the actor associated with this behavior.
+ *
+ * @return the actor
*/
protected ActorRef actor() {
return context.getActor();
}
/**
- * Get the term from the last entry in the log
+ * Returns the term of the last entry in the log.
*
- * @return
+ * @return the term
*/
protected long lastTerm() {
return context.getReplicatedLog().lastTerm();
}
/**
- * Get the index from the last entry in the log
+ * Returns the index of the last entry in the log.
*
- * @return
+ * @return the index
*/
protected long lastIndex() {
return context.getReplicatedLog().lastIndex();
}
/**
- * Find the client request tracker for a specific logIndex
- *
- * @param logIndex
- * @return
+ * Removes and returns the ClientRequestTracker for the specified log index.
+ * @param logIndex the log index
+ * @return the ClientRequestTracker or null if none available
*/
- protected ClientRequestTracker findClientRequestTracker(long logIndex) {
+ protected ClientRequestTracker removeClientRequestTracker(final long logIndex) {
return null;
}
/**
- * Find the log index from the previous to last entry in the log
+ * Returns the actual index of the entry in replicated log for the given index or -1 if not found.
*
- * @return
+ * @return the log entry index or -1 if not found
*/
- protected long prevLogIndex(long index){
- ReplicatedLogEntry prevEntry =
- context.getReplicatedLog().get(index - 1);
- if (prevEntry != null) {
- return prevEntry.getIndex();
+ protected long getLogEntryIndex(final long index) {
+ if (index == context.getReplicatedLog().getSnapshotIndex()) {
+ return context.getReplicatedLog().getSnapshotIndex();
+ }
+
+ ReplicatedLogEntry entry = context.getReplicatedLog().get(index);
+ if (entry != null) {
+ return entry.getIndex();
}
+
return -1;
}
/**
- * Find the log term from the previous to last entry in the log
- * @return
+ * Returns the actual term of the entry in the replicated log for the given index or -1 if not found.
+ *
+ * @return the log entry term or -1 if not found
*/
- protected long prevLogTerm(long index){
- ReplicatedLogEntry prevEntry =
- context.getReplicatedLog().get(index - 1);
- if (prevEntry != null) {
- return prevEntry.getTerm();
+ protected long getLogEntryTerm(final 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
+ * Returns the actual term of the entry in the replicated log for the given index or, if not present, returns the
+ * snapshot term if the given index is in the snapshot or -1 otherwise.
*
- * @param index a log index that is known to be committed
+ * @return the term or -1 otherwise
*/
- protected void applyLogToStateMachine(long index) {
+ protected long getLogEntryOrSnapshotTerm(final long index) {
+ if (context.getReplicatedLog().isInSnapshot(index)) {
+ return context.getReplicatedLog().getSnapshotTerm();
+ }
+
+ return getLogEntryTerm(index);
+ }
+
+ /**
+ * Applies the log entries up to the specified index that is known to be committed to the state machine.
+ *
+ * @param index the log index
+ */
+ protected void applyLogToStateMachine(final long index) {
// 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);
-
- if (tracker != null) {
- clientActor = tracker.getClientActor();
- identifier = tracker.getIdentifier();
- }
- ReplicatedLogEntry replicatedLogEntry =
- context.getReplicatedLog().get(i);
+ for (long i = context.getLastApplied() + 1; i < index + 1; i++) {
+ ReplicatedLogEntry replicatedLogEntry = context.getReplicatedLog().get(i);
if (replicatedLogEntry != null) {
- actor().tell(new ApplyState(clientActor, identifier,
- replicatedLogEntry), actor());
+ // 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 applyState;
+ final ClientRequestTracker tracker = removeClientRequestTracker(i);
+ if (tracker != null) {
+ applyState = new ApplyState(tracker.getClientActor(), tracker.getIdentifier(), replicatedLogEntry);
+ } else {
+ applyState = new ApplyState(null, null, replicatedLogEntry);
+ }
+
+ log.debug("{}: Setting last applied to {}", logName(), i);
+
+ context.setLastApplied(i);
+ context.getApplyStateConsumer().accept(applyState);
} 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.setLastApplied(index);
- }
- protected Object fromSerializableMessage(Object serializable){
- return SerializationUtils.fromSerializable(serializable);
+ // 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 RaftState handleMessage(ActorRef sender, Object message) {
+ public RaftActorBehavior handleMessage(final ActorRef sender, final Object message) {
if (message instanceof AppendEntries) {
return appendEntries(sender, (AppendEntries) message);
} else if (message instanceof AppendEntriesReply) {
return requestVote(sender, (RequestVote) message);
} else if (message instanceof RequestVoteReply) {
return handleRequestVoteReply(sender, (RequestVoteReply) message);
+ } else {
+ return null;
+ }
+ }
+
+ @Override
+ public RaftActorBehavior switchBehavior(final RaftActorBehavior behavior) {
+ return internalSwitchBehavior(behavior);
+ }
+
+ protected RaftActorBehavior internalSwitchBehavior(final RaftState newState) {
+ return internalSwitchBehavior(createBehavior(context, newState));
+ }
+
+ @SuppressWarnings("checkstyle:IllegalCatch")
+ protected RaftActorBehavior internalSwitchBehavior(final RaftActorBehavior newBehavior) {
+ if (!context.getRaftPolicy().automaticElectionsEnabled()) {
+ return this;
+ }
+
+ log.info("{} :- Switching from behavior {} to {}, election term: {}", logName(), this.state(),
+ newBehavior.state(), context.getTermInformation().getCurrentTerm());
+ try {
+ close();
+ } catch (RuntimeException e) {
+ log.error("{}: Failed to close behavior : {}", logName(), this.state(), e);
+ }
+ return newBehavior;
+ }
+
+
+ protected int getMajorityVoteCount(final 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
+ * lastApplied-1 which ever is minimum.
+ *
+ * @param snapshotCapturedIndex the index from which to clear
+ */
+ protected void performSnapshotWithoutCapture(final long snapshotCapturedIndex) {
+ long actualIndex = context.getSnapshotManager().trimLog(snapshotCapturedIndex);
+
+ if (actualIndex != -1) {
+ setReplicatedToAllIndex(actualIndex);
}
- return state();
}
- @Override public String getLeaderId() {
- return leaderId;
+ protected String getId() {
+ return context.getId();
}
}
Code Review / controller.git / blobdiff