X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?p=controller.git;a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-akka-raft%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fcluster%2Fraft%2FRaftActorServerConfigurationSupport.java;h=46fe6269e37a907db36fe3d0ca7a5b9b9b52bd58;hp=7c8888b9f4c60735adfc8fed6e39df97244d1c29;hb=d639c62a1e743ec846b15bf755b830b00f4cc7eb;hpb=5aa58404a8ee1ad053742780439823309360a3a1 diff --git a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/RaftActorServerConfigurationSupport.java b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/RaftActorServerConfigurationSupport.java index 7c8888b9f4..46fe6269e3 100644 --- a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/RaftActorServerConfigurationSupport.java +++ b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/RaftActorServerConfigurationSupport.java @@ -11,20 +11,28 @@ import akka.actor.ActorRef; import akka.actor.ActorSelection; import akka.actor.Cancellable; import com.google.common.base.Preconditions; +import java.util.ArrayDeque; import java.util.ArrayList; -import java.util.Collections; -import java.util.LinkedList; +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 java.util.concurrent.TimeUnit; -import org.opendaylight.controller.cluster.raft.FollowerLogInformation.FollowerState; +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.FollowerCatchUpTimeout; +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.slf4j.Logger; @@ -41,38 +49,95 @@ class RaftActorServerConfigurationSupport { private final OperationState IDLE = new Idle(); + private final RaftActor raftActor; + private final RaftActorContext raftContext; - private final Queue> pendingOperationsQueue = new LinkedList<>(); + private final Queue> pendingOperationsQueue = new ArrayDeque<>(); private OperationState currentOperationState = IDLE; - RaftActorServerConfigurationSupport(RaftActorContext context) { - this.raftContext = context; + 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 FollowerCatchUpTimeout) { - currentOperationState.onFollowerCatchupTimeout(raftActor, (FollowerCatchUpTimeout)message); + } 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(raftActor, - (UnInitializedFollowerSnapshotReply)message); + currentOperationState.onUnInitializedFollowerSnapshotReply((UnInitializedFollowerSnapshotReply) message); return true; } else if(message instanceof ApplyState) { - return onApplyState((ApplyState) message, raftActor); + return onApplyState((ApplyState) message); + } else if(message instanceof SnapshotComplete) { + currentOperationState.onSnapshotComplete(); + return false; } else { return false; } } - private boolean onApplyState(ApplyState applyState, RaftActor raftActor) { + void onNewLeader(String leaderId) { + currentOperationState.onNewLeader(leaderId); + } + + private void onChangeServersVotingStatus(ChangeServersVotingStatus message, ActorRef sender) { + LOG.debug("{}: onChangeServersVotingStatus: {}, state: {}", raftContext.getId(), message, + currentOperationState); + + // 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)); + } + } + + 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)); + } + } + + private boolean onApplyState(ApplyState applyState) { Payload data = applyState.getReplicatedLogEntry().getData(); if(data instanceof ServerConfigurationPayload) { - currentOperationState.onApplyState(raftActor, applyState); + currentOperationState.onApplyState(applyState); return true; } @@ -100,20 +165,20 @@ class RaftActorServerConfigurationSupport { *
  • Respond to caller with TIMEOUT.
    • * */ - private void onAddServer(AddServer addServer, RaftActor raftActor, ActorRef sender) { - LOG.debug("{}: onAddServer: {}", raftContext.getId(), addServer); + private void onAddServer(AddServer addServer, ActorRef sender) { + LOG.debug("{}: onAddServer: {}, state: {}", raftContext.getId(), addServer, currentOperationState); - onNewOperation(raftActor, new AddServerContext(addServer, sender)); + onNewOperation(new AddServerContext(addServer, sender)); } - private void onNewOperation(RaftActor raftActor, ServerOperationContext operationContext) { + private void onNewOperation(ServerOperationContext operationContext) { if (raftActor.isLeader()) { - currentOperationState.onNewOperation(raftActor, operationContext); + currentOperationState.onNewOperation(operationContext); } else { ActorSelection leader = raftActor.getLeader(); if (leader != null) { LOG.debug("{}: Not leader - forwarding to leader {}", raftContext.getId(), leader); - leader.forward(operationContext.getOperation(), raftActor.getContext()); + leader.tell(operationContext.getOperation(), operationContext.getClientRequestor()); } else { LOG.debug("{}: No leader - returning NO_LEADER reply", raftContext.getId()); operationContext.getClientRequestor().tell(operationContext.newReply( @@ -122,32 +187,18 @@ class RaftActorServerConfigurationSupport { } } - /** - * Interface for a server operation FSM state. - */ - private interface OperationState { - void onNewOperation(RaftActor raftActor, ServerOperationContext operationContext); - - void onFollowerCatchupTimeout(RaftActor raftActor, FollowerCatchUpTimeout followerTimeout); - - void onUnInitializedFollowerSnapshotReply(RaftActor raftActor, UnInitializedFollowerSnapshotReply reply); - - void onApplyState(RaftActor raftActor, ApplyState applyState); - } - /** * Interface for the initial state for a server operation. */ private interface InitialOperationState { - void initiate(RaftActor raftActor); + void initiate(); } /** - * Abstract base class for server operation FSM state. Handles common behavior for all states. + * Abstract base class for a server operation FSM state. Handles common behavior for all states. */ - private abstract class AbstractOperationState implements OperationState { - @Override - public void onNewOperation(RaftActor raftActor, ServerOperationContext operationContext) { + 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(), @@ -156,50 +207,76 @@ class RaftActorServerConfigurationSupport { pendingOperationsQueue.add(operationContext); } - @Override - public void onFollowerCatchupTimeout(RaftActor raftActor, FollowerCatchUpTimeout followerTimeout) { - LOG.debug("onFollowerCatchupTimeout should not be called in state {}", this); + void onServerOperationTimeout(ServerOperationTimeout timeout) { + LOG.debug("onServerOperationTimeout should not be called in state {}", this); } - @Override - public void onUnInitializedFollowerSnapshotReply(RaftActor raftActor, UnInitializedFollowerSnapshotReply reply) { + void onUnInitializedFollowerSnapshotReply(UnInitializedFollowerSnapshotReply reply) { LOG.debug("onUnInitializedFollowerSnapshotReply was called in state {}", this); } - @Override - public void onApplyState(RaftActor raftActor, ApplyState applyState) { + void onApplyState(ApplyState applyState) { LOG.debug("onApplyState was called in state {}", this); } - protected void persistNewServerConfiguration(RaftActor raftActor, ServerOperationContext operationContext){ - List newConfig = new ArrayList(raftContext.getPeerIds()); - newConfig.add(raftContext.getId()); + void onSnapshotComplete() { + + } + + void onNewLeader(String newLeader) { + } - LOG.debug("{}: New server configuration : {}", raftContext.getId(), newConfig); + protected void persistNewServerConfiguration(ServerOperationContext operationContext){ + raftContext.setDynamicServerConfigurationInUse(); - ServerConfigurationPayload payload = new ServerConfigurationPayload(newConfig, Collections.emptyList()); + 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); + currentOperationState = new Persisting(operationContext, newTimer(new ServerOperationTimeout( + operationContext.getLoggingContext()))); + + sendReply(operationContext, ServerChangeStatus.OK); } - protected void operationComplete(RaftActor raftActor, ServerOperationContext operationContext, - ServerChangeStatus status) { + protected void operationComplete(ServerOperationContext operationContext, @Nullable ServerChangeStatus replyStatus) { + if(replyStatus != null) { + sendReply(operationContext, replyStatus); + } - LOG.debug("{}: Returning {} for operation {}", raftContext.getId(), status, operationContext.getOperation()); + operationContext.operationComplete(raftActor, replyStatus == null || replyStatus == ServerChangeStatus.OK); - operationContext.getClientRequestor().tell(operationContext.newReply(status, raftActor.getLeaderId()), - raftActor.self()); + changeToIdleState(); + } + protected void changeToIdleState() { currentOperationState = IDLE; ServerOperationContext nextOperation = pendingOperationsQueue.poll(); if(nextOperation != null) { - RaftActorServerConfigurationSupport.this.onNewOperation(raftActor, nextOperation); + 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(); @@ -209,14 +286,14 @@ class RaftActorServerConfigurationSupport { /** * The state when no server operation is in progress. It immediately initiates new server operations. */ - private class Idle extends AbstractOperationState { + private final class Idle extends OperationState { @Override - public void onNewOperation(RaftActor raftActor, ServerOperationContext operationContext) { - operationContext.newInitialOperationState(RaftActorServerConfigurationSupport.this).initiate(raftActor); + public void onNewOperation(ServerOperationContext operationContext) { + operationContext.newInitialOperationState(RaftActorServerConfigurationSupport.this).initiate(); } @Override - public void onApplyState(RaftActor raftActor, ApplyState applyState) { + public void onApplyState(ApplyState applyState) { // Noop - we override b/c ApplyState is called normally for followers in the idle state. } } @@ -224,22 +301,50 @@ class RaftActorServerConfigurationSupport { /** * The state when a new server configuration is being persisted and replicated. */ - private class Persisting extends AbstractOperationState { + private final class Persisting extends OperationState { private final ServerOperationContext operationContext; + private final Cancellable timer; + private boolean timedOut = false; - Persisting(ServerOperationContext operationContext) { + Persisting(ServerOperationContext operationContext, Cancellable timer) { this.operationContext = operationContext; + this.timer = timer; } @Override - public void onApplyState(RaftActor raftActor, ApplyState applyState) { + 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", + LOG.info("{}: {} has been successfully replicated to a majority of followers", raftContext.getId(), applyState.getReplicatedLogEntry().getData()); - operationComplete(raftActor, operationContext, ServerChangeStatus.OK); + 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); } } } @@ -247,7 +352,7 @@ class RaftActorServerConfigurationSupport { /** * Abstract base class for an AddServer operation state. */ - private abstract class AddServerState extends AbstractOperationState { + private abstract class AddServerState extends OperationState { private final AddServerContext addServerContext; AddServerState(AddServerContext addServerContext) { @@ -257,51 +362,76 @@ class RaftActorServerConfigurationSupport { 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 class InitialAddServerState extends AddServerState implements InitialOperationState { + private final class InitialAddServerState extends AddServerState implements InitialOperationState { InitialAddServerState(AddServerContext addServerContext) { super(addServerContext); } @Override - public void initiate(RaftActor raftActor) { + public void initiate() { AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior(); - AddServer addServer = getAddServerContext().getOperation(); LOG.debug("{}: Initiating {}", raftContext.getId(), addServer); - raftContext.addToPeers(addServer.getNewServerId(), addServer.getNewServerAddress()); - - // if voting member - initialize to VOTING_NOT_INITIALIZED - FollowerState initialState = addServer.isVotingMember() ? FollowerState.VOTING_NOT_INITIALIZED : - FollowerState.NON_VOTING; - leader.addFollower(addServer.getNewServerId(), initialState); + if(raftContext.getPeerInfo(addServer.getNewServerId()) != null) { + operationComplete(getAddServerContext(), ServerChangeStatus.ALREADY_EXISTS); + return; + } - if(initialState == FollowerState.VOTING_NOT_INITIALIZED){ - LOG.debug("{}: Leader sending initiate capture snapshot to new follower {}", raftContext.getId(), - addServer.getNewServerId()); + VotingState votingState = addServer.isVotingMember() ? VotingState.VOTING_NOT_INITIALIZED : + VotingState.NON_VOTING; + raftContext.addToPeers(addServer.getNewServerId(), addServer.getNewServerAddress(), votingState); - leader.initiateCaptureSnapshot(addServer.getNewServerId()); + leader.addFollower(addServer.getNewServerId()); + if(votingState == VotingState.VOTING_NOT_INITIALIZED){ // schedule the install snapshot timeout timer - Cancellable installSnapshotTimer = raftContext.getActorSystem().scheduler().scheduleOnce( - new FiniteDuration(((raftContext.getConfigParams().getElectionTimeOutInterval().toMillis()) * 2), - TimeUnit.MILLISECONDS), raftContext.getActor(), - new FollowerCatchUpTimeout(addServer.getNewServerId()), - raftContext.getActorSystem().dispatcher(), raftContext.getActor()); - - currentOperationState = new InstallingSnapshot(getAddServerContext(), installSnapshotTimer); + 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(raftActor, getAddServerContext()); + persistNewServerConfiguration(getAddServerContext()); } } } @@ -310,7 +440,7 @@ class RaftActorServerConfigurationSupport { * The AddServer operation state for when the catch-up snapshot is being installed. It handles successful * reply or timeout. */ - private class InstallingSnapshot extends AddServerState { + private final class InstallingSnapshot extends AddServerState { private final Cancellable installSnapshotTimer; InstallingSnapshot(AddServerContext addServerContext, Cancellable installSnapshotTimer) { @@ -319,41 +449,76 @@ class RaftActorServerConfigurationSupport { } @Override - public void onFollowerCatchupTimeout(RaftActor raftActor, FollowerCatchUpTimeout followerTimeout) { - String serverId = followerTimeout.getNewServerId(); - - LOG.debug("{}: onFollowerCatchupTimeout: {}", raftContext.getId(), serverId); - - AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior(); - - // cleanup - raftContext.removePeer(serverId); - leader.removeFollower(serverId); - - LOG.warn("{}: Timeout occured for new server {} while installing snapshot", raftContext.getId(), serverId); + public void onServerOperationTimeout(ServerOperationTimeout timeout) { + handleInstallSnapshotTimeout(timeout); - operationComplete(raftActor, getAddServerContext(), ServerChangeStatus.TIMEOUT); + LOG.warn("{}: Timeout occured for new server {} while installing snapshot", raftContext.getId(), + timeout.getLoggingContext()); } @Override - public void onUnInitializedFollowerSnapshotReply(RaftActor raftActor, UnInitializedFollowerSnapshotReply reply) { + 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)) { + if(getAddServerContext().getOperation().getNewServerId().equals(followerId) && raftActor.isLeader()) { AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior(); - FollowerLogInformation followerLogInformation = leader.getFollower(followerId); + 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"); + } + } + } - followerLogInformation.setFollowerState(FollowerState.VOTING); - leader.updateMinReplicaCountAndMinIsolatedLeaderPeerCount(); + /** + * 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()); - persistNewServerConfiguration(raftActor, getAddServerContext()); + 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()); } } @@ -385,9 +550,18 @@ class RaftActorServerConfigurationSupport { 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(); } /** @@ -407,5 +581,265 @@ class RaftActorServerConfigurationSupport { 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 { + 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 { + 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) { + 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 { + updateLocalPeerInfo(); + + persistNewServerConfiguration(changeVotingStatusContext); + } + } + + private void initiateLocalLeaderElection() { + LOG.debug("{}: Sending local ElectionTimeout to start leader election", raftContext.getId()); + + ServerConfigurationPayload previousServerConfig = raftContext.getPeerServerInfo(true); + updateLocalPeerInfo(); + + raftContext.getActor().tell(ElectionTimeout.INSTANCE, raftContext.getActor()); + + currentOperationState = new WaitingForLeaderElected(changeVotingStatusContext, previousServerConfig); + } + + private void updateLocalPeerInfo() { + List newServerInfoList = newServerInfoList(); + + raftContext.updatePeerIds(new ServerConfigurationPayload(newServerInfoList)); + if(raftActor.getCurrentBehavior() instanceof AbstractLeader) { + AbstractLeader leader = (AbstractLeader) raftActor.getCurrentBehavior(); + leader.updateMinReplicaCount(); + } + } + + private List newServerInfoList() { + Map serverVotingStatusMap = changeVotingStatusContext.getOperation().getServerVotingStatusMap(); + List 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 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 serverVotingStatusMap = operationContext.getOperation().getServerVotingStatusMap(); + ActorSelection forwardToPeerActor = null; + for(Map.Entry 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; + } } }