import akka.actor.ActorRef;
import akka.actor.ActorSelection;
-import org.opendaylight.controller.cluster.raft.FollowerLogInformation.FollowerState;
+import akka.actor.Cancellable;
+import com.google.common.base.Preconditions;
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Queue;
+import java.util.UUID;
+import javax.annotation.Nullable;
+import org.opendaylight.controller.cluster.raft.ServerConfigurationPayload.ServerInfo;
+import org.opendaylight.controller.cluster.raft.base.messages.ApplyState;
+import org.opendaylight.controller.cluster.raft.base.messages.ElectionTimeout;
+import org.opendaylight.controller.cluster.raft.base.messages.SnapshotComplete;
import org.opendaylight.controller.cluster.raft.behaviors.AbstractLeader;
import org.opendaylight.controller.cluster.raft.messages.AddServer;
import org.opendaylight.controller.cluster.raft.messages.AddServerReply;
+import org.opendaylight.controller.cluster.raft.messages.ChangeServersVotingStatus;
+import org.opendaylight.controller.cluster.raft.messages.RemoveServer;
+import org.opendaylight.controller.cluster.raft.messages.RemoveServerReply;
+import org.opendaylight.controller.cluster.raft.messages.ServerChangeReply;
import org.opendaylight.controller.cluster.raft.messages.ServerChangeStatus;
+import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
+import org.opendaylight.controller.cluster.raft.messages.UnInitializedFollowerSnapshotReply;
+import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
+import org.opendaylight.yangtools.concepts.Identifier;
+import org.opendaylight.yangtools.util.AbstractUUIDIdentifier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
+import scala.concurrent.duration.FiniteDuration;
/**
* Handles server configuration related messages for a RaftActor.
class RaftActorServerConfigurationSupport {
private static final Logger LOG = LoggerFactory.getLogger(RaftActorServerConfigurationSupport.class);
- private final RaftActorContext context;
+ private final OperationState IDLE = new Idle();
- RaftActorServerConfigurationSupport(RaftActorContext context) {
- this.context = context;
+ private final RaftActor raftActor;
+
+ private final RaftActorContext raftContext;
+
+ private final Queue<ServerOperationContext<?>> pendingOperationsQueue = new ArrayDeque<>();
+
+ private OperationState currentOperationState = IDLE;
+
+ RaftActorServerConfigurationSupport(RaftActor raftActor) {
+ this.raftActor = raftActor;
+ this.raftContext = raftActor.getRaftActorContext();
}
- boolean handleMessage(Object message, RaftActor raftActor, ActorRef sender) {
+ boolean handleMessage(Object message, ActorRef sender) {
if(message instanceof AddServer) {
- onAddServer((AddServer)message, raftActor, sender);
+ onAddServer((AddServer) message, sender);
+ return true;
+ } else if(message instanceof RemoveServer) {
+ onRemoveServer((RemoveServer) message, sender);
+ return true;
+ } else if(message instanceof ChangeServersVotingStatus) {
+ onChangeServersVotingStatus((ChangeServersVotingStatus) message, sender);
+ return true;
+ } else if (message instanceof ServerOperationTimeout) {
+ currentOperationState.onServerOperationTimeout((ServerOperationTimeout) message);
+ return true;
+ } else if (message instanceof UnInitializedFollowerSnapshotReply) {
+ currentOperationState.onUnInitializedFollowerSnapshotReply((UnInitializedFollowerSnapshotReply) message);
return true;
+ } else if(message instanceof ApplyState) {
+ return onApplyState((ApplyState) message);
+ } else if(message instanceof SnapshotComplete) {
+ currentOperationState.onSnapshotComplete();
+ return false;
} else {
return false;
}
}
- private void onAddServer(AddServer addServer, RaftActor raftActor, ActorRef sender) {
- LOG.debug("onAddServer: {}", addServer);
+ void onNewLeader(String leaderId) {
+ currentOperationState.onNewLeader(leaderId);
+ }
+
+ private void onChangeServersVotingStatus(ChangeServersVotingStatus message, ActorRef sender) {
+ LOG.debug("{}: onChangeServersVotingStatus: {}, state: {}", raftContext.getId(), message,
+ currentOperationState);
- if(noLeaderOrForwardedToLeader(addServer, raftActor, sender)) {
- return;
+ // The following check is a special case. Normally we fail an operation if there's no leader.
+ // Consider a scenario where one has 2 geographically-separated 3-node clusters, one a primary and
+ // the other a backup such that if the primary cluster is lost, the backup can take over. In this
+ // scenario, we have a logical 6-node cluster where the primary sub-cluster is configured as voting
+ // and the backup sub-cluster as non-voting such that the primary cluster can make progress without
+ // consensus from the backup cluster while still replicating to the backup. On fail-over to the backup,
+ // a request would be sent to a member of the backup cluster to flip the voting states, ie make the
+ // backup sub-cluster voting and the lost primary non-voting. However since the primary majority
+ // cluster is lost, there would be no leader to apply, persist and replicate the server config change.
+ // Therefore, if the local server is currently non-voting and is to be changed to voting and there is
+ // no current leader, we will try to elect a leader using the new server config in order to replicate
+ // the change and progress.
+ boolean localServerChangingToVoting = Boolean.TRUE.equals(message.
+ getServerVotingStatusMap().get(raftActor.getRaftActorContext().getId()));
+ boolean hasNoLeader = raftActor.getLeaderId() == null;
+ if(localServerChangingToVoting && !raftContext.isVotingMember() && hasNoLeader) {
+ currentOperationState.onNewOperation(new ChangeServersVotingStatusContext(message, sender, true));
+ } else {
+ onNewOperation(new ChangeServersVotingStatusContext(message, sender, false));
}
+ }
- // TODO - check if a server config is in progress. If so, cache this AddServer request to be processed
- // after the current one is done.
+ private void onRemoveServer(RemoveServer removeServer, ActorRef sender) {
+ LOG.debug("{}: onRemoveServer: {}, state: {}", raftContext.getId(), removeServer, currentOperationState);
+ boolean isSelf = removeServer.getServerId().equals(raftContext.getId());
+ if(isSelf && !raftContext.hasFollowers()) {
+ sender.tell(new RemoveServerReply(ServerChangeStatus.NOT_SUPPORTED, raftActor.getLeaderId()),
+ raftActor.getSelf());
+ } else if(!isSelf && !raftContext.getPeerIds().contains(removeServer.getServerId())) {
+ sender.tell(new RemoveServerReply(ServerChangeStatus.DOES_NOT_EXIST, raftActor.getLeaderId()),
+ raftActor.getSelf());
+ } else {
+ String serverAddress = isSelf ? raftActor.self().path().toString() :
+ raftContext.getPeerAddress(removeServer.getServerId());
+ onNewOperation(new RemoveServerContext(removeServer, serverAddress, sender));
+ }
+ }
- context.addToPeers(addServer.getNewServerId(), addServer.getNewServerAddress());
+ private boolean onApplyState(ApplyState applyState) {
+ Payload data = applyState.getReplicatedLogEntry().getData();
+ if(data instanceof ServerConfigurationPayload) {
+ currentOperationState.onApplyState(applyState);
+ return true;
+ }
- AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior();
- FollowerState initialState = addServer.isVotingMember() ? FollowerState.VOTING_NOT_INITIALIZED :
- FollowerState.NON_VOTING;
- leader.addFollower(addServer.getNewServerId(), initialState);
+ return false;
+ }
- // TODO
- // if initialState == FollowerState.VOTING_NOT_INITIALIZED
- // Initiate snapshot via leader.initiateCaptureSnapshot(addServer.getNewServerId())
- // Start a timer to abort the operation after a period of time (maybe 2 times election timeout)
- // Set local instance state and wait for message from the AbstractLeader when install snapshot is done and return now
- // When install snapshot message is received, go to step 1
- // else
- // go to step 2
- //
- // 1) tell AbstractLeader mark the follower as VOTING and recalculate minReplicationCount and
- // minIsolatedLeaderPeerCount
- // 2) persist and replicate ServerConfigurationPayload via
- // raftActor.persistData(sender, uuid, newServerConfigurationPayload)
- // 3) Wait for commit complete via ApplyState message in RaftActor or time it out. In RaftActor,
- // on ApplyState, check if ReplicatedLogEntry payload is ServerConfigurationPayload and call
- // this class.
- //
+ /**
+ * The algorithm for AddServer is as follows:
+ * <ul>
+ * <li>Add the new server as a peer.</li>
+ * <li>Add the new follower to the leader.</li>
+ * <li>If new server should be voting member</li>
+ * <ul>
+ * <li>Initialize FollowerState to VOTING_NOT_INITIALIZED.</li>
+ * <li>Initiate install snapshot to the new follower.</li>
+ * <li>When install snapshot complete, mark the follower as VOTING and re-calculate majority vote count.</li>
+ * </ul>
+ * <li>Persist and replicate ServerConfigurationPayload with the new server list.</li>
+ * <li>On replication consensus, respond to caller with OK.</li>
+ * </ul>
+ * If the install snapshot times out after a period of 2 * election time out
+ * <ul>
+ * <li>Remove the new server as a peer.</li>
+ * <li>Remove the new follower from the leader.</li>
+ * <li>Respond to caller with TIMEOUT.</li>
+ * </ul>
+ */
+ private void onAddServer(AddServer addServer, ActorRef sender) {
+ LOG.debug("{}: onAddServer: {}, state: {}", raftContext.getId(), addServer, currentOperationState);
- // TODO - temporary
- sender.tell(new AddServerReply(ServerChangeStatus.OK, raftActor.getLeaderId()), raftActor.self());
+ onNewOperation(new AddServerContext(addServer, sender));
}
- private boolean noLeaderOrForwardedToLeader(Object message, RaftActor raftActor, ActorRef sender) {
+ private void onNewOperation(ServerOperationContext<?> operationContext) {
if (raftActor.isLeader()) {
- return false;
+ currentOperationState.onNewOperation(operationContext);
+ } else {
+ ActorSelection leader = raftActor.getLeader();
+ if (leader != null) {
+ LOG.debug("{}: Not leader - forwarding to leader {}", raftContext.getId(), leader);
+ leader.tell(operationContext.getOperation(), operationContext.getClientRequestor());
+ } else {
+ LOG.debug("{}: No leader - returning NO_LEADER reply", raftContext.getId());
+ operationContext.getClientRequestor().tell(operationContext.newReply(
+ ServerChangeStatus.NO_LEADER, null), raftActor.self());
+ }
}
+ }
- ActorSelection leader = raftActor.getLeader();
- if (leader != null) {
- LOG.debug("Not leader - forwarding to leader {}", leader);
- leader.forward(message, raftActor.getContext());
- } else {
- LOG.debug("No leader - returning NO_LEADER AddServerReply");
- sender.tell(new AddServerReply(ServerChangeStatus.NO_LEADER, null), raftActor.self());
+ /**
+ * Interface for the initial state for a server operation.
+ */
+ private interface InitialOperationState {
+ void initiate();
+ }
+
+ /**
+ * Abstract base class for a server operation FSM state. Handles common behavior for all states.
+ */
+ private abstract class OperationState {
+ void onNewOperation(ServerOperationContext<?> operationContext) {
+ // We're currently processing another operation so queue it to be processed later.
+
+ LOG.debug("{}: Server operation already in progress - queueing {}", raftContext.getId(),
+ operationContext.getOperation());
+
+ pendingOperationsQueue.add(operationContext);
+ }
+
+ void onServerOperationTimeout(ServerOperationTimeout timeout) {
+ LOG.debug("onServerOperationTimeout should not be called in state {}", this);
+ }
+
+ void onUnInitializedFollowerSnapshotReply(UnInitializedFollowerSnapshotReply reply) {
+ LOG.debug("onUnInitializedFollowerSnapshotReply was called in state {}", this);
+ }
+
+ void onApplyState(ApplyState applyState) {
+ LOG.debug("onApplyState was called in state {}", this);
+ }
+
+ void onSnapshotComplete() {
+
+ }
+
+ void onNewLeader(String newLeader) {
+ }
+
+ protected void persistNewServerConfiguration(ServerOperationContext<?> operationContext){
+ raftContext.setDynamicServerConfigurationInUse();
+
+ ServerConfigurationPayload payload = raftContext.getPeerServerInfo(
+ operationContext.includeSelfInNewConfiguration(raftActor));
+ LOG.debug("{}: New server configuration : {}", raftContext.getId(), payload.getServerConfig());
+
+ raftActor.persistData(operationContext.getClientRequestor(), operationContext.getContextId(), payload);
+
+ currentOperationState = new Persisting(operationContext, newTimer(new ServerOperationTimeout(
+ operationContext.getLoggingContext())));
+
+ sendReply(operationContext, ServerChangeStatus.OK);
+ }
+
+ protected void operationComplete(ServerOperationContext<?> operationContext, @Nullable ServerChangeStatus replyStatus) {
+ if(replyStatus != null) {
+ sendReply(operationContext, replyStatus);
+ }
+
+ operationContext.operationComplete(raftActor, replyStatus == null || replyStatus == ServerChangeStatus.OK);
+
+ changeToIdleState();
}
- return true;
+ protected void changeToIdleState() {
+ currentOperationState = IDLE;
+
+ ServerOperationContext<?> nextOperation = pendingOperationsQueue.poll();
+ if(nextOperation != null) {
+ RaftActorServerConfigurationSupport.this.onNewOperation(nextOperation);
+ }
+ }
+
+ protected void sendReply(ServerOperationContext<?> operationContext, ServerChangeStatus status) {
+ LOG.debug("{}: Returning {} for operation {}", raftContext.getId(), status, operationContext.getOperation());
+
+ operationContext.getClientRequestor().tell(operationContext.newReply(status, raftActor.getLeaderId()),
+ raftActor.self());
+ }
+
+ Cancellable newTimer(Object message) {
+ return newTimer(raftContext.getConfigParams().getElectionTimeOutInterval().$times(2), message);
+ }
+
+ Cancellable newTimer(FiniteDuration timeout, Object message) {
+ return raftContext.getActorSystem().scheduler().scheduleOnce(
+ timeout, raftContext.getActor(), message,
+ raftContext.getActorSystem().dispatcher(), raftContext.getActor());
+ }
+
+ @Override
+ public String toString() {
+ return getClass().getSimpleName();
+ }
+ }
+
+ /**
+ * The state when no server operation is in progress. It immediately initiates new server operations.
+ */
+ private final class Idle extends OperationState {
+ @Override
+ public void onNewOperation(ServerOperationContext<?> operationContext) {
+ operationContext.newInitialOperationState(RaftActorServerConfigurationSupport.this).initiate();
+ }
+
+ @Override
+ public void onApplyState(ApplyState applyState) {
+ // Noop - we override b/c ApplyState is called normally for followers in the idle state.
+ }
+ }
+
+ /**
+ * The state when a new server configuration is being persisted and replicated.
+ */
+ private final class Persisting extends OperationState {
+ private final ServerOperationContext<?> operationContext;
+ private final Cancellable timer;
+ private boolean timedOut = false;
+
+ Persisting(ServerOperationContext<?> operationContext, Cancellable timer) {
+ this.operationContext = operationContext;
+ this.timer = timer;
+ }
+
+ @Override
+ public void onApplyState(ApplyState applyState) {
+ // Sanity check - we could get an ApplyState from a previous operation that timed out so make
+ // sure it's meant for us.
+ if(operationContext.getContextId().equals(applyState.getIdentifier())) {
+ LOG.info("{}: {} has been successfully replicated to a majority of followers", raftContext.getId(),
+ applyState.getReplicatedLogEntry().getData());
+
+ timer.cancel();
+ operationComplete(operationContext, null);
+ }
+ }
+
+ @Override
+ public void onServerOperationTimeout(ServerOperationTimeout timeout) {
+ LOG.warn("{}: Timeout occured while replicating the new server configuration for {}", raftContext.getId(),
+ timeout.getLoggingContext());
+
+ timedOut = true;
+
+ // Fail any pending operations
+ ServerOperationContext<?> nextOperation = pendingOperationsQueue.poll();
+ while(nextOperation != null) {
+ sendReply(nextOperation, ServerChangeStatus.PRIOR_REQUEST_CONSENSUS_TIMEOUT);
+ nextOperation = pendingOperationsQueue.poll();
+ }
+ }
+
+ @Override
+ public void onNewOperation(ServerOperationContext<?> operationContext) {
+ if(timedOut) {
+ sendReply(operationContext, ServerChangeStatus.PRIOR_REQUEST_CONSENSUS_TIMEOUT);
+ } else {
+ super.onNewOperation(operationContext);
+ }
+ }
+ }
+
+ /**
+ * Abstract base class for an AddServer operation state.
+ */
+ private abstract class AddServerState extends OperationState {
+ private final AddServerContext addServerContext;
+
+ AddServerState(AddServerContext addServerContext) {
+ this.addServerContext = addServerContext;
+ }
+
+ AddServerContext getAddServerContext() {
+ return addServerContext;
+ }
+
+ Cancellable newInstallSnapshotTimer() {
+ return newTimer(new ServerOperationTimeout(addServerContext.getOperation().getNewServerId()));
+ }
+
+ void handleInstallSnapshotTimeout(ServerOperationTimeout timeout) {
+ String serverId = timeout.getLoggingContext();
+
+ LOG.debug("{}: handleInstallSnapshotTimeout for new server {}", raftContext.getId(), serverId);
+
+ // cleanup
+ raftContext.removePeer(serverId);
+
+ boolean isLeader = raftActor.isLeader();
+ if(isLeader) {
+ AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior();
+ leader.removeFollower(serverId);
+ }
+
+ operationComplete(getAddServerContext(), isLeader ? ServerChangeStatus.TIMEOUT : ServerChangeStatus.NO_LEADER);
+ }
+
+ }
+
+ /**
+ * The initial state for the AddServer operation. It adds the new follower as a peer and initiates
+ * snapshot capture, if necessary.
+ */
+ private final class InitialAddServerState extends AddServerState implements InitialOperationState {
+ InitialAddServerState(AddServerContext addServerContext) {
+ super(addServerContext);
+ }
+
+ @Override
+ public void initiate() {
+ AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior();
+ AddServer addServer = getAddServerContext().getOperation();
+
+ LOG.debug("{}: Initiating {}", raftContext.getId(), addServer);
+
+ if(raftContext.getPeerInfo(addServer.getNewServerId()) != null) {
+ operationComplete(getAddServerContext(), ServerChangeStatus.ALREADY_EXISTS);
+ return;
+ }
+
+ VotingState votingState = addServer.isVotingMember() ? VotingState.VOTING_NOT_INITIALIZED :
+ VotingState.NON_VOTING;
+ raftContext.addToPeers(addServer.getNewServerId(), addServer.getNewServerAddress(), votingState);
+
+ leader.addFollower(addServer.getNewServerId());
+
+ if(votingState == VotingState.VOTING_NOT_INITIALIZED){
+ // schedule the install snapshot timeout timer
+ Cancellable installSnapshotTimer = newInstallSnapshotTimer();
+ if(leader.initiateCaptureSnapshot(addServer.getNewServerId())) {
+ LOG.debug("{}: Initiating capture snapshot for new server {}", raftContext.getId(),
+ addServer.getNewServerId());
+
+ currentOperationState = new InstallingSnapshot(getAddServerContext(), installSnapshotTimer);
+ } else {
+ LOG.debug("{}: Snapshot already in progress - waiting for completion", raftContext.getId());
+
+ currentOperationState = new WaitingForPriorSnapshotComplete(getAddServerContext(),
+ installSnapshotTimer);
+ }
+ } else {
+ LOG.debug("{}: New follower is non-voting - directly persisting new server configuration",
+ raftContext.getId());
+
+ persistNewServerConfiguration(getAddServerContext());
+ }
+ }
+ }
+
+ /**
+ * The AddServer operation state for when the catch-up snapshot is being installed. It handles successful
+ * reply or timeout.
+ */
+ private final class InstallingSnapshot extends AddServerState {
+ private final Cancellable installSnapshotTimer;
+
+ InstallingSnapshot(AddServerContext addServerContext, Cancellable installSnapshotTimer) {
+ super(addServerContext);
+ this.installSnapshotTimer = Preconditions.checkNotNull(installSnapshotTimer);
+ }
+
+ @Override
+ public void onServerOperationTimeout(ServerOperationTimeout timeout) {
+ handleInstallSnapshotTimeout(timeout);
+
+ LOG.warn("{}: Timeout occured for new server {} while installing snapshot", raftContext.getId(),
+ timeout.getLoggingContext());
+ }
+
+ @Override
+ public void onUnInitializedFollowerSnapshotReply(UnInitializedFollowerSnapshotReply reply) {
+ LOG.debug("{}: onUnInitializedFollowerSnapshotReply: {}", raftContext.getId(), reply);
+
+ String followerId = reply.getFollowerId();
+
+ // Sanity check to guard against receiving an UnInitializedFollowerSnapshotReply from a prior
+ // add server operation that timed out.
+ if(getAddServerContext().getOperation().getNewServerId().equals(followerId) && raftActor.isLeader()) {
+ AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior();
+ raftContext.getPeerInfo(followerId).setVotingState(VotingState.VOTING);
+ leader.updateMinReplicaCount();
+
+ persistNewServerConfiguration(getAddServerContext());
+
+ installSnapshotTimer.cancel();
+ } else {
+ LOG.debug("{}: Dropping UnInitializedFollowerSnapshotReply for server {}: {}",
+ raftContext.getId(), followerId,
+ !raftActor.isLeader() ? "not leader" : "server Id doesn't match");
+ }
+ }
+ }
+
+ /**
+ * The AddServer operation state for when there is a snapshot already in progress. When the current
+ * snapshot completes, it initiates an install snapshot.
+ */
+ private final class WaitingForPriorSnapshotComplete extends AddServerState {
+ private final Cancellable snapshotTimer;
+
+ WaitingForPriorSnapshotComplete(AddServerContext addServerContext, Cancellable snapshotTimer) {
+ super(addServerContext);
+ this.snapshotTimer = Preconditions.checkNotNull(snapshotTimer);
+ }
+
+ @Override
+ public void onSnapshotComplete() {
+ LOG.debug("{}: onSnapshotComplete", raftContext.getId());
+
+ if(!raftActor.isLeader()) {
+ LOG.debug("{}: No longer the leader", raftContext.getId());
+ return;
+ }
+
+ AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior();
+ if(leader.initiateCaptureSnapshot(getAddServerContext().getOperation().getNewServerId())) {
+ LOG.debug("{}: Initiating capture snapshot for new server {}", raftContext.getId(),
+ getAddServerContext().getOperation().getNewServerId());
+
+ currentOperationState = new InstallingSnapshot(getAddServerContext(),
+ newInstallSnapshotTimer());
+
+ snapshotTimer.cancel();
+ }
+ }
+
+ @Override
+ public void onServerOperationTimeout(ServerOperationTimeout timeout) {
+ handleInstallSnapshotTimeout(timeout);
+
+ LOG.warn("{}: Timeout occured for new server {} while waiting for prior snapshot to complete",
+ raftContext.getId(), timeout.getLoggingContext());
+ }
+ }
+
+ private static final class ServerOperationContextIdentifier extends AbstractUUIDIdentifier<ServerOperationContextIdentifier> {
+ private static final long serialVersionUID = 1L;
+
+ ServerOperationContextIdentifier() {
+ super(UUID.randomUUID());
+ }
+ }
+
+ /**
+ * Stores context information for a server operation.
+ *
+ * @param <T> the operation type
+ */
+ private static abstract class ServerOperationContext<T> {
+ private final T operation;
+ private final ActorRef clientRequestor;
+ private final Identifier contextId;
+
+ ServerOperationContext(T operation, ActorRef clientRequestor){
+ this.operation = operation;
+ this.clientRequestor = clientRequestor;
+ contextId = new ServerOperationContextIdentifier();
+ }
+
+ Identifier getContextId() {
+ return contextId;
+ }
+
+ T getOperation() {
+ return operation;
+ }
+
+ ActorRef getClientRequestor() {
+ return clientRequestor;
+ }
+
+ void operationComplete(RaftActor raftActor, boolean succeeded) {
+ }
+
+ boolean includeSelfInNewConfiguration(RaftActor raftActor) {
+ return true;
+ }
+
+ abstract Object newReply(ServerChangeStatus status, String leaderId);
+
+ abstract InitialOperationState newInitialOperationState(RaftActorServerConfigurationSupport support);
+
+ abstract String getLoggingContext();
+ }
+
+ /**
+ * Stores context information for an AddServer operation.
+ */
+ private static class AddServerContext extends ServerOperationContext<AddServer> {
+ AddServerContext(AddServer addServer, ActorRef clientRequestor) {
+ super(addServer, clientRequestor);
+ }
+
+ @Override
+ Object newReply(ServerChangeStatus status, String leaderId) {
+ return new AddServerReply(status, leaderId);
+ }
+
+ @Override
+ InitialOperationState newInitialOperationState(RaftActorServerConfigurationSupport support) {
+ return support.new InitialAddServerState(this);
+ }
+
+ @Override
+ String getLoggingContext() {
+ return getOperation().getNewServerId();
+ }
+ }
+
+ private abstract class RemoveServerState extends OperationState {
+ private final RemoveServerContext removeServerContext;
+
+ protected RemoveServerState(RemoveServerContext removeServerContext) {
+ this.removeServerContext = Preconditions.checkNotNull(removeServerContext);
+
+ }
+
+ public RemoveServerContext getRemoveServerContext() {
+ return removeServerContext;
+ }
+ }
+
+ private final class InitialRemoveServerState extends RemoveServerState implements InitialOperationState{
+
+ protected InitialRemoveServerState(RemoveServerContext removeServerContext) {
+ super(removeServerContext);
+ }
+
+ @Override
+ public void initiate() {
+ String serverId = getRemoveServerContext().getOperation().getServerId();
+ raftContext.removePeer(serverId);
+ ((AbstractLeader)raftActor.getCurrentBehavior()).removeFollower(serverId);
+
+ persistNewServerConfiguration(getRemoveServerContext());
+ }
+ }
+
+ private static class RemoveServerContext extends ServerOperationContext<RemoveServer> {
+ private final String peerAddress;
+
+ RemoveServerContext(RemoveServer operation, String peerAddress, ActorRef clientRequestor) {
+ super(operation, clientRequestor);
+ this.peerAddress = peerAddress;
+ }
+
+ @Override
+ Object newReply(ServerChangeStatus status, String leaderId) {
+ return new RemoveServerReply(status, leaderId);
+ }
+
+ @Override
+ InitialOperationState newInitialOperationState(RaftActorServerConfigurationSupport support) {
+ return support.new InitialRemoveServerState(this);
+ }
+
+ @Override
+ void operationComplete(RaftActor raftActor, boolean succeeded) {
+ if(peerAddress != null) {
+ raftActor.context().actorSelection(peerAddress).tell(new ServerRemoved(getOperation().getServerId()), raftActor.getSelf());
+ }
+ }
+
+ @Override
+ boolean includeSelfInNewConfiguration(RaftActor raftActor) {
+ return !getOperation().getServerId().equals(raftActor.getId());
+ }
+
+ @Override
+ String getLoggingContext() {
+ return getOperation().getServerId();
+ }
+ }
+
+ private static class ChangeServersVotingStatusContext extends ServerOperationContext<ChangeServersVotingStatus> {
+ private final boolean tryToElectLeader;
+
+ ChangeServersVotingStatusContext(ChangeServersVotingStatus convertMessage, ActorRef clientRequestor,
+ boolean tryToElectLeader) {
+ super(convertMessage, clientRequestor);
+ this.tryToElectLeader = tryToElectLeader;
+ }
+
+ @Override
+ InitialOperationState newInitialOperationState(RaftActorServerConfigurationSupport support) {
+ return support.new ChangeServersVotingStatusState(this, tryToElectLeader);
+ }
+
+ @Override
+ Object newReply(ServerChangeStatus status, String leaderId) {
+ return new ServerChangeReply(status, leaderId);
+ }
+
+ @Override
+ void operationComplete(final RaftActor raftActor, boolean succeeded) {
+ // If this leader changed to non-voting we need to step down as leader so we'll try to transfer
+ // leadership.
+ boolean localServerChangedToNonVoting = Boolean.FALSE.equals(getOperation().
+ getServerVotingStatusMap().get(raftActor.getRaftActorContext().getId()));
+ if (succeeded && localServerChangedToNonVoting) {
+ LOG.debug("Leader changed to non-voting - trying leadership transfer");
+ raftActor.becomeNonVoting();
+ }
+ }
+
+ @Override
+ String getLoggingContext() {
+ return getOperation().toString();
+ }
+ }
+
+ private class ChangeServersVotingStatusState extends OperationState implements InitialOperationState {
+ private final ChangeServersVotingStatusContext changeVotingStatusContext;
+ private final boolean tryToElectLeader;
+
+ ChangeServersVotingStatusState(ChangeServersVotingStatusContext changeVotingStatusContext,
+ boolean tryToElectLeader) {
+ this.changeVotingStatusContext = changeVotingStatusContext;
+ this.tryToElectLeader = tryToElectLeader;
+ }
+
+ @Override
+ public void initiate() {
+ LOG.debug("Initiating ChangeServersVotingStatusState");
+
+ if(tryToElectLeader) {
+ initiateLocalLeaderElection();
+ } else if(updateLocalPeerInfo()) {
+ persistNewServerConfiguration(changeVotingStatusContext);
+ }
+ }
+
+ private void initiateLocalLeaderElection() {
+ LOG.debug("{}: Sending local ElectionTimeout to start leader election", raftContext.getId());
+
+ ServerConfigurationPayload previousServerConfig = raftContext.getPeerServerInfo(true);
+ if(!updateLocalPeerInfo()) {
+ return;
+ }
+
+ raftContext.getActor().tell(ElectionTimeout.INSTANCE, raftContext.getActor());
+
+ currentOperationState = new WaitingForLeaderElected(changeVotingStatusContext, previousServerConfig);
+ }
+
+ private boolean updateLocalPeerInfo() {
+ List<ServerInfo> newServerInfoList = newServerInfoList();
+
+ // Check if new voting state would leave us with no voting members.
+ boolean atLeastOneVoting = false;
+ for(ServerInfo info: newServerInfoList) {
+ if(info.isVoting()) {
+ atLeastOneVoting = true;
+ break;
+ }
+ }
+
+ if(!atLeastOneVoting) {
+ operationComplete(changeVotingStatusContext, ServerChangeStatus.INVALID_REQUEST);
+ return false;
+ }
+
+ raftContext.updatePeerIds(new ServerConfigurationPayload(newServerInfoList));
+ if(raftActor.getCurrentBehavior() instanceof AbstractLeader) {
+ AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior();
+ leader.updateMinReplicaCount();
+ }
+
+ return true;
+ }
+
+ private List<ServerInfo> newServerInfoList() {
+ Map<String, Boolean> serverVotingStatusMap = changeVotingStatusContext.getOperation().getServerVotingStatusMap();
+ List<ServerInfo> newServerInfoList = new ArrayList<>();
+ for(String peerId: raftContext.getPeerIds()) {
+ newServerInfoList.add(new ServerInfo(peerId, serverVotingStatusMap.containsKey(peerId) ?
+ serverVotingStatusMap.get(peerId) : raftContext.getPeerInfo(peerId).isVoting()));
+ }
+
+ newServerInfoList.add(new ServerInfo(raftContext.getId(), serverVotingStatusMap.containsKey(
+ raftContext.getId()) ? serverVotingStatusMap.get(raftContext.getId()) : raftContext.isVotingMember()));
+
+ return newServerInfoList;
+ }
+ }
+
+ private class WaitingForLeaderElected extends OperationState {
+ private final ServerConfigurationPayload previousServerConfig;
+ private final ChangeServersVotingStatusContext operationContext;
+ private final Cancellable timer;
+
+ WaitingForLeaderElected(ChangeServersVotingStatusContext operationContext,
+ ServerConfigurationPayload previousServerConfig) {
+ this.operationContext = operationContext;
+ this.previousServerConfig = previousServerConfig;
+
+ timer = newTimer(raftContext.getConfigParams().getElectionTimeOutInterval(),
+ new ServerOperationTimeout(operationContext.getLoggingContext()));
+ }
+
+ @Override
+ void onNewLeader(String newLeader) {
+ LOG.debug("{}: New leader {} elected", raftContext.getId(), newLeader);
+
+ timer.cancel();
+
+ if(raftActor.isLeader()) {
+ persistNewServerConfiguration(operationContext);
+ } else {
+ // Edge case - some other node became leader so forward the operation.
+ LOG.debug("{}: Forwarding {} to new leader", raftContext.getId(), operationContext.getOperation());
+
+ // Revert the local server config change.
+ raftContext.updatePeerIds(previousServerConfig);
+
+ changeToIdleState();
+ RaftActorServerConfigurationSupport.this.onNewOperation(operationContext);
+ }
+ }
+
+ @Override
+ void onServerOperationTimeout(ServerOperationTimeout timeout) {
+ LOG.warn("{}: Leader election timed out - cannot apply operation {}",
+ raftContext.getId(), timeout.getLoggingContext());
+
+ // Revert the local server config change.
+ raftContext.updatePeerIds(previousServerConfig);
+ raftActor.initializeBehavior();
+
+ tryToForwardOperationToAnotherServer();
+ }
+
+ private void tryToForwardOperationToAnotherServer() {
+ Collection<String> serversVisited = new HashSet<>(operationContext.getOperation().getServersVisited());
+
+ LOG.debug("{}: tryToForwardOperationToAnotherServer - servers already visited {}", raftContext.getId(),
+ serversVisited);
+
+ serversVisited.add(raftContext.getId());
+
+ // Try to find another whose state is being changed from non-voting to voting and that we haven't
+ // tried yet.
+ Map<String, Boolean> serverVotingStatusMap = operationContext.getOperation().getServerVotingStatusMap();
+ ActorSelection forwardToPeerActor = null;
+ for(Map.Entry<String, Boolean> e: serverVotingStatusMap.entrySet()) {
+ Boolean isVoting = e.getValue();
+ String serverId = e.getKey();
+ PeerInfo peerInfo = raftContext.getPeerInfo(serverId);
+ if(isVoting && peerInfo != null && !peerInfo.isVoting() && !serversVisited.contains(serverId)) {
+ ActorSelection actor = raftContext.getPeerActorSelection(serverId);
+ if(actor != null) {
+ forwardToPeerActor = actor;
+ break;
+ }
+ }
+ }
+
+ if(forwardToPeerActor != null) {
+ LOG.debug("{}: Found server {} to forward to", raftContext.getId(), forwardToPeerActor);
+
+ forwardToPeerActor.tell(new ChangeServersVotingStatus(serverVotingStatusMap, serversVisited),
+ operationContext.getClientRequestor());
+ changeToIdleState();
+ } else {
+ operationComplete(operationContext, ServerChangeStatus.NO_LEADER);
+ }
+ }
+ }
+
+ static class ServerOperationTimeout {
+ private final String loggingContext;
+
+ ServerOperationTimeout(String loggingContext){
+ this.loggingContext = Preconditions.checkNotNull(loggingContext, "loggingContext should not be null");
+ }
+
+ String getLoggingContext() {
+ return loggingContext;
+ }
}
}
Code Review / controller.git / blobdiff