/** * Copyright (C) 2009-2013 Typesafe Inc. */ package akka.cluster import language.existentials import language.postfixOps import scala.collection.immutable import scala.concurrent.duration._ import scala.concurrent.forkjoin.ThreadLocalRandom import scala.util.control.NonFatal import java.util.UUID import akka.actor.{ Actor, ActorLogging, ActorRef, Address, Cancellable, Props, PoisonPill, ReceiveTimeout, RootActorPath, Scheduler } import akka.actor.OneForOneStrategy import akka.actor.SupervisorStrategy.Stop import akka.cluster.MemberStatus._ import akka.cluster.ClusterEvent._ import akka.actor.ActorSelection import akka.dispatch.{ UnboundedMessageQueueSemantics, RequiresMessageQueue } /** * Base trait for all cluster messages. All ClusterMessage's are serializable. */ trait ClusterMessage extends Serializable /** * INTERNAL API * Cluster commands sent by the USER via * [[akka.cluster.Cluster]] extension * or JMX. */ private[cluster] object ClusterUserAction { /** * Command to initiate join another node (represented by `address`). * Join will be sent to the other node. */ @SerialVersionUID(1L) case class JoinTo(address: Address) /** * Command to leave the cluster. */ @SerialVersionUID(1L) case class Leave(address: Address) extends ClusterMessage /** * Command to mark node as temporary down. */ @SerialVersionUID(1L) case class Down(address: Address) extends ClusterMessage } /** * INTERNAL API */ private[cluster] object InternalClusterAction { /** * Command to join the cluster. Sent when a node wants to join another node (the receiver). * @param node the node that wants to join the cluster */ @SerialVersionUID(1L) case class Join(node: UniqueAddress, roles: Set[String]) extends ClusterMessage /** * Reply to Join * @param from the sender node in the cluster, i.e. the node that received the Join command */ @SerialVersionUID(1L) case class Welcome(from: UniqueAddress, gossip: Gossip) extends ClusterMessage /** * Command to initiate the process to join the specified * seed nodes. */ case class JoinSeedNodes(seedNodes: immutable.IndexedSeq[Address]) /** * Start message of the process to join one of the seed nodes. * The node sends `InitJoin` to all seed nodes, which replies * with `InitJoinAck`. The first reply is used others are discarded. * The node sends `Join` command to the seed node that replied first. * If a node is uninitialized it will reply to `InitJoin` with * `InitJoinNack`. */ case object JoinSeedNode /** * @see JoinSeedNode */ @SerialVersionUID(1L) case object InitJoin extends ClusterMessage /** * @see JoinSeedNode */ @SerialVersionUID(1L) case class InitJoinAck(address: Address) extends ClusterMessage /** * @see JoinSeedNode */ @SerialVersionUID(1L) case class InitJoinNack(address: Address) extends ClusterMessage /** * Marker interface for periodic tick messages */ sealed trait Tick case object GossipTick extends Tick case object HeartbeatTick extends Tick case object ReapUnreachableTick extends Tick case object MetricsTick extends Tick case object LeaderActionsTick extends Tick case object PublishStatsTick extends Tick case class SendGossipTo(address: Address) case object GetClusterCoreRef case class PublisherCreated(publisher: ActorRef) /** * Comand to [[akka.cluster.ClusterDaemon]] to create a * [[akka.cluster.OnMemberUpListener]]. */ case class AddOnMemberUpListener(callback: Runnable) sealed trait SubscriptionMessage case class Subscribe(subscriber: ActorRef, to: Class[_]) extends SubscriptionMessage case class Unsubscribe(subscriber: ActorRef, to: Option[Class[_]]) extends SubscriptionMessage /** * @param receiver if `receiver` is defined the event will only be sent to that * actor, otherwise it will be sent to all subscribers via the `eventStream`. */ case class PublishCurrentClusterState(receiver: Option[ActorRef]) extends SubscriptionMessage sealed trait PublishMessage case class PublishChanges(newGossip: Gossip) extends PublishMessage case class PublishEvent(event: ClusterDomainEvent) extends PublishMessage } /** * INTERNAL API. * * Cluster commands sent by the LEADER. */ private[cluster] object ClusterLeaderAction { /** * Command to mark a node to be removed from the cluster immediately. * Can only be sent by the leader. * @param node the node to exit, i.e. destination of the message */ @SerialVersionUID(1L) case class Exit(node: UniqueAddress) extends ClusterMessage /** * Command to remove a node from the cluster immediately. * @param node the node to shutdown, i.e. destination of the message */ @SerialVersionUID(1L) case class Shutdown(node: UniqueAddress) extends ClusterMessage } /** * INTERNAL API. * * Supervisor managing the different Cluster daemons. */ private[cluster] final class ClusterDaemon(settings: ClusterSettings) extends Actor with ActorLogging with RequiresMessageQueue[UnboundedMessageQueueSemantics] { import InternalClusterAction._ // Important - don't use Cluster(context.system) here because that would // cause deadlock. The Cluster extension is currently being created and is waiting // for response from GetClusterCoreRef in its constructor. val coreSupervisor = context.actorOf(Props[ClusterCoreSupervisor]. withDispatcher(context.props.dispatcher), name = "core") context.actorOf(Props[ClusterHeartbeatReceiver]. withDispatcher(context.props.dispatcher), name = "heartbeatReceiver") def receive = { case msg @ GetClusterCoreRef ⇒ coreSupervisor forward msg case AddOnMemberUpListener(code) ⇒ context.actorOf(Props(classOf[OnMemberUpListener], code)) case PublisherCreated(publisher) ⇒ if (settings.MetricsEnabled) { // metrics must be started after core/publisher to be able // to inject the publisher ref to the ClusterMetricsCollector context.actorOf(Props(classOf[ClusterMetricsCollector], publisher). withDispatcher(context.props.dispatcher), name = "metrics") } } } /** * INTERNAL API. * * ClusterCoreDaemon and ClusterDomainEventPublisher can't be restarted because the state * would be obsolete. Shutdown the member if any those actors crashed. */ private[cluster] final class ClusterCoreSupervisor extends Actor with ActorLogging with RequiresMessageQueue[UnboundedMessageQueueSemantics] { import InternalClusterAction._ val publisher = context.actorOf(Props[ClusterDomainEventPublisher]. withDispatcher(context.props.dispatcher), name = "publisher") val coreDaemon = context.watch(context.actorOf(Props(classOf[ClusterCoreDaemon], publisher). withDispatcher(context.props.dispatcher), name = "daemon")) context.parent ! PublisherCreated(publisher) override val supervisorStrategy = OneForOneStrategy() { case NonFatal(e) ⇒ log.error(e, "Cluster node [{}] crashed, [{}] - shutting down...", Cluster(context.system).selfAddress, e.getMessage) self ! PoisonPill Stop } override def postStop(): Unit = Cluster(context.system).shutdown() def receive = { case InternalClusterAction.GetClusterCoreRef ⇒ sender ! coreDaemon } } /** * INTERNAL API. */ private[cluster] final class ClusterCoreDaemon(publisher: ActorRef) extends Actor with ActorLogging with RequiresMessageQueue[UnboundedMessageQueueSemantics] { import ClusterLeaderAction._ import InternalClusterAction._ val cluster = Cluster(context.system) import cluster.{ selfAddress, selfUniqueAddress, scheduler, failureDetector } import cluster.settings._ def vclockName(node: UniqueAddress): String = node.address + "-" + node.uid val vclockNode = VectorClock.Node(vclockName(selfUniqueAddress)) // note that self is not initially member, // and the Gossip is not versioned for this 'Node' yet var latestGossip: Gossip = Gossip.empty var stats = ClusterStats() var seedNodeProcess: Option[ActorRef] = None /** * Looks up and returns the remote cluster command connection for the specific address. */ private def clusterCore(address: Address): ActorSelection = context.actorSelection(RootActorPath(address) / "system" / "cluster" / "core" / "daemon") val heartbeatSender = context.actorOf(Props[ClusterHeartbeatSender]. withDispatcher(UseDispatcher), name = "heartbeatSender") import context.dispatcher // start periodic gossip to random nodes in cluster val gossipTask = scheduler.schedule(PeriodicTasksInitialDelay.max(GossipInterval), GossipInterval, self, GossipTick) // start periodic cluster failure detector reaping (moving nodes condemned by the failure detector to unreachable list) val failureDetectorReaperTask = scheduler.schedule(PeriodicTasksInitialDelay.max(UnreachableNodesReaperInterval), UnreachableNodesReaperInterval, self, ReapUnreachableTick) // start periodic leader action management (only applies for the current leader) val leaderActionsTask = scheduler.schedule(PeriodicTasksInitialDelay.max(LeaderActionsInterval), LeaderActionsInterval, self, LeaderActionsTick) // start periodic publish of current stats val publishStatsTask: Option[Cancellable] = PublishStatsInterval match { case Duration.Zero | Duration.Undefined | Duration.Inf ⇒ None case d: FiniteDuration ⇒ Some(scheduler.schedule(PeriodicTasksInitialDelay.max(d), d, self, PublishStatsTick)) } override def preStart(): Unit = { if (AutoJoin) self ! JoinSeedNodes(SeedNodes) } override def postStop(): Unit = { gossipTask.cancel() failureDetectorReaperTask.cancel() leaderActionsTask.cancel() publishStatsTask foreach { _.cancel() } } def uninitialized: Actor.Receive = { case InitJoin ⇒ sender ! InitJoinNack(selfAddress) case ClusterUserAction.JoinTo(address) ⇒ join(address) case JoinSeedNodes(seedNodes) ⇒ joinSeedNodes(seedNodes) case msg: SubscriptionMessage ⇒ publisher forward msg } def tryingToJoin(joinWith: Address, deadline: Option[Deadline]): Actor.Receive = { case Welcome(from, gossip) ⇒ welcome(joinWith, from, gossip) case InitJoin ⇒ sender ! InitJoinNack(selfAddress) case ClusterUserAction.JoinTo(address) ⇒ context.become(uninitialized) join(address) case JoinSeedNodes(seedNodes) ⇒ context.become(uninitialized) joinSeedNodes(seedNodes) case msg: SubscriptionMessage ⇒ publisher forward msg case _: Tick ⇒ if (deadline.exists(_.isOverdue)) { context.become(uninitialized) if (AutoJoin) joinSeedNodes(SeedNodes) else join(joinWith) } } def initialized: Actor.Receive = { case msg: GossipEnvelope ⇒ receiveGossip(msg) case msg: GossipStatus ⇒ receiveGossipStatus(msg) case GossipTick ⇒ gossip() case ReapUnreachableTick ⇒ reapUnreachableMembers() case LeaderActionsTick ⇒ leaderActions() case PublishStatsTick ⇒ publishInternalStats() case InitJoin ⇒ initJoin() case Join(node, roles) ⇒ joining(node, roles) case ClusterUserAction.Down(address) ⇒ downing(address) case ClusterUserAction.Leave(address) ⇒ leaving(address) case Exit(node) ⇒ exiting(node) case Shutdown(node) ⇒ shutdown(node) case SendGossipTo(address) ⇒ sendGossipTo(address) case msg: SubscriptionMessage ⇒ publisher forward msg case ClusterUserAction.JoinTo(address) ⇒ log.info("Trying to join [{}] when already part of a cluster, ignoring", address) } def removed: Actor.Receive = { case msg: SubscriptionMessage ⇒ publisher forward msg } def receive = uninitialized override def unhandled(message: Any): Unit = message match { case _: Tick ⇒ case _: GossipEnvelope ⇒ case _: GossipStatus ⇒ case other ⇒ super.unhandled(other) } def initJoin(): Unit = sender ! InitJoinAck(selfAddress) def joinSeedNodes(seedNodes: immutable.IndexedSeq[Address]): Unit = { require(seedNodeProcess.isEmpty, "Join seed nodes is already in progress") seedNodeProcess = if (seedNodes.isEmpty || seedNodes == immutable.IndexedSeq(selfAddress)) { self ! ClusterUserAction.JoinTo(selfAddress) None } else if (seedNodes.head == selfAddress) { Some(context.actorOf(Props(classOf[FirstSeedNodeProcess], seedNodes). withDispatcher(UseDispatcher), name = "firstSeedNodeProcess")) } else { Some(context.actorOf(Props(classOf[JoinSeedNodeProcess], seedNodes). withDispatcher(UseDispatcher), name = "joinSeedNodeProcess")) } } /** * Try to join this cluster node with the node specified by `address`. * It's only allowed to join from an empty state, i.e. when not already a member. * A `Join(selfUniqueAddress)` command is sent to the node to join, * which will reply with a `Welcome` message. */ def join(address: Address): Unit = { if (address.protocol != selfAddress.protocol) log.warning("Trying to join member with wrong protocol, but was ignored, expected [{}] but was [{}]", selfAddress.protocol, address.protocol) else if (address.system != selfAddress.system) log.warning("Trying to join member with wrong ActorSystem name, but was ignored, expected [{}] but was [{}]", selfAddress.system, address.system) else { require(latestGossip.members.isEmpty, "Join can only be done from empty state") // to support manual join when joining to seed nodes is stuck (no seed nodes available) val snd = sender seedNodeProcess match { case Some(`snd`) ⇒ // seedNodeProcess completed, it will stop itself seedNodeProcess = None case Some(s) ⇒ // manual join, abort current seedNodeProcess context stop s seedNodeProcess = None case None ⇒ // no seedNodeProcess in progress } if (address == selfAddress) { context.become(initialized) joining(selfUniqueAddress, cluster.selfRoles) } else { val joinDeadline = RetryUnsuccessfulJoinAfter match { case Duration.Undefined | Duration.Inf ⇒ None case d: FiniteDuration ⇒ Some(Deadline.now + d) } context.become(tryingToJoin(address, joinDeadline)) clusterCore(address) ! Join(selfUniqueAddress, cluster.selfRoles) } } } /** * State transition to JOINING - new node joining. * Received `Join` message and replies with `Welcome` message, containing * current gossip state, including the new joining member. */ def joining(node: UniqueAddress, roles: Set[String]): Unit = { if (node.address.protocol != selfAddress.protocol) log.warning("Member with wrong protocol tried to join, but was ignored, expected [{}] but was [{}]", selfAddress.protocol, node.address.protocol) else if (node.address.system != selfAddress.system) log.warning("Member with wrong ActorSystem name tried to join, but was ignored, expected [{}] but was [{}]", selfAddress.system, node.address.system) else { val localMembers = latestGossip.members val localUnreachable = latestGossip.overview.unreachable // check by address without uid to make sure that node with same host:port is not allowed // to join until previous node with that host:port has been removed from the cluster val alreadyMember = localMembers.exists(_.address == node.address) val isUnreachable = localUnreachable.exists(_.address == node.address) if (alreadyMember) log.info("Existing member [{}] is trying to join, ignoring", node) else if (isUnreachable) log.info("Unreachable member [{}] is trying to join, ignoring", node) else { // remove the node from the failure detector failureDetector.remove(node.address) // add joining node as Joining // add self in case someone else joins before self has joined (Set discards duplicates) val newMembers = localMembers + Member(node, roles) + Member(selfUniqueAddress, cluster.selfRoles) val newGossip = latestGossip copy (members = newMembers) val versionedGossip = newGossip :+ vclockNode val seenVersionedGossip = versionedGossip seen selfUniqueAddress latestGossip = seenVersionedGossip log.info("Cluster Node [{}] - Node [{}] is JOINING, roles [{}]", selfAddress, node.address, roles.mkString(", ")) if (node != selfUniqueAddress) { sender ! Welcome(selfUniqueAddress, latestGossip) } publish(latestGossip) } } } /** * Reply from Join request. */ def welcome(joinWith: Address, from: UniqueAddress, gossip: Gossip): Unit = { require(latestGossip.members.isEmpty, "Join can only be done from empty state") if (joinWith != from.address) log.info("Ignoring welcome from [{}] when trying to join with [{}]", from.address, joinWith) else { log.info("Cluster Node [{}] - Welcome from [{}]", selfAddress, from.address) latestGossip = gossip seen selfUniqueAddress publish(latestGossip) if (from != selfUniqueAddress) gossipTo(from, sender) context.become(initialized) } } /** * State transition to LEAVING. * The node will eventually be removed by the leader, after hand-off in EXITING, and only after * removal a new node with same address can join the cluster through the normal joining procedure. */ def leaving(address: Address): Unit = { // only try to update if the node is available (in the member ring) if (latestGossip.members.exists(m ⇒ m.address == address && m.status == Up)) { val newMembers = latestGossip.members map { m ⇒ if (m.address == address) m.copy(status = Leaving) else m } // mark node as LEAVING val newGossip = latestGossip copy (members = newMembers) val versionedGossip = newGossip :+ vclockNode val seenVersionedGossip = versionedGossip seen selfUniqueAddress latestGossip = seenVersionedGossip log.info("Cluster Node [{}] - Marked address [{}] as [{}]", selfAddress, address, Leaving) publish(latestGossip) } } /** * State transition to EXITING. */ def exiting(node: UniqueAddress): Unit = if (node == selfUniqueAddress) { log.info("Cluster Node [{}] - Marked as [{}]", selfAddress, Exiting) // TODO implement when we need hand-off } /** * This method is only called after the LEADER has sent a Shutdown message - telling the node * to shut down himself. */ def shutdown(node: UniqueAddress): Unit = if (node == selfUniqueAddress) { log.info("Cluster Node [{}] - Node has been REMOVED by the leader - shutting down...", selfAddress) cluster.shutdown() } /** * State transition to DOW. * The node to DOWN is removed from the `members` set and put in the `unreachable` set (if not already there) * and its status is set to DOWN. The node is also removed from the `seen` table. * * The node will eventually be removed by the leader, and only after removal a new node with same address can * join the cluster through the normal joining procedure. */ def downing(address: Address): Unit = { val localGossip = latestGossip val localMembers = localGossip.members val localOverview = localGossip.overview val localSeen = localOverview.seen val localUnreachableMembers = localOverview.unreachable // 1. check if the node to DOWN is in the `members` set val downedMember: Option[Member] = localMembers.collectFirst { case m if m.address == address ⇒ m.copy(status = Down) } val newMembers = downedMember match { case Some(m) ⇒ log.info("Cluster Node [{}] - Marking node [{}] as [{}]", selfAddress, m.address, Down) localMembers - m case None ⇒ localMembers } // 2. check if the node to DOWN is in the `unreachable` set val newUnreachableMembers = localUnreachableMembers.map { member ⇒ // no need to DOWN members already DOWN if (member.address == address && member.status != Down) { log.info("Cluster Node [{}] - Marking unreachable node [{}] as [{}]", selfAddress, member.address, Down) member copy (status = Down) } else member } // 3. add the newly DOWNED members from the `members` (in step 1.) to the `newUnreachableMembers` set. val newUnreachablePlusNewlyDownedMembers = newUnreachableMembers ++ downedMember // 4. remove nodes marked as DOWN from the `seen` table val newSeen = localSeen -- newUnreachablePlusNewlyDownedMembers.collect { case m if m.status == Down ⇒ m.uniqueAddress } // update gossip overview val newOverview = localOverview copy (seen = newSeen, unreachable = newUnreachablePlusNewlyDownedMembers) val newGossip = localGossip copy (overview = newOverview, members = newMembers) // update gossip val versionedGossip = newGossip :+ vclockNode latestGossip = versionedGossip seen selfUniqueAddress publish(latestGossip) } def receiveGossipStatus(status: GossipStatus): Unit = { val from = status.from if (latestGossip.overview.unreachable.exists(_.uniqueAddress == from)) log.info("Ignoring received gossip status from unreachable [{}] ", from) else if (latestGossip.members.forall(_.uniqueAddress != from)) log.info("Ignoring received gossip status from unknown [{}]", from) else { (status.version tryCompareTo latestGossip.version) match { case Some(0) ⇒ // same version case Some(x) if x > 0 ⇒ gossipStatusTo(from, sender) // remote is newer case _ ⇒ gossipTo(from, sender) // conflicting or local is newer } } } /** * Receive new gossip. */ def receiveGossip(envelope: GossipEnvelope): Unit = { val from = envelope.from val remoteGossip = envelope.gossip val localGossip = latestGossip if (envelope.to != selfUniqueAddress) log.info("Ignoring received gossip intended for someone else, from [{}] to [{}]", from.address, envelope.to) if (remoteGossip.overview.unreachable.exists(_.address == selfAddress)) log.info("Ignoring received gossip with myself as unreachable, from [{}]", selfAddress, from.address) else if (localGossip.overview.unreachable.exists(_.uniqueAddress == from)) log.info("Ignoring received gossip from unreachable [{}] ", from) else if (localGossip.members.forall(_.uniqueAddress != from)) log.info("Ignoring received gossip from unknown [{}]", from) else if (remoteGossip.members.forall(_.uniqueAddress != selfUniqueAddress)) log.info("Ignoring received gossip that does not contain myself, from [{}]", from) else { val comparison = remoteGossip.version tryCompareTo localGossip.version val (winningGossip, talkback, newStats) = comparison match { case None ⇒ // conflicting versions, merge (remoteGossip merge localGossip, true, stats.incrementMergeCount) case Some(0) ⇒ // same version (remoteGossip mergeSeen localGossip, !remoteGossip.seenByNode(selfUniqueAddress), stats.incrementSameCount) case Some(x) if x < 0 ⇒ // local is newer (localGossip, true, stats.incrementNewerCount) case _ ⇒ // remote is newer (remoteGossip, !remoteGossip.seenByNode(selfUniqueAddress), stats.incrementOlderCount) } stats = newStats latestGossip = winningGossip seen selfUniqueAddress // for all new joining nodes we remove them from the failure detector latestGossip.members foreach { node ⇒ if (node.status == Joining && !localGossip.members(node)) failureDetector.remove(node.address) } log.debug("Cluster Node [{}] - Receiving gossip from [{}]", selfAddress, from) if (comparison.isEmpty) { log.debug( """Couldn't establish a causal relationship between "remote" gossip and "local" gossip - Remote[{}] - Local[{}] - merged them into [{}]""", remoteGossip, localGossip, winningGossip) } stats = stats.incrementReceivedGossipCount publish(latestGossip) if (talkback) { // send back gossip to sender when sender had different view, i.e. merge, or sender had // older or sender had newer gossipTo(from, sender) } } } def mergeRate(count: Long): Double = (count * 1000.0) / GossipInterval.toMillis /** * Initiates a new round of gossip. */ def gossip(): Unit = { log.debug("Cluster Node [{}] - Initiating new round of gossip", selfAddress) if (!isSingletonCluster && isAvailable) { val localGossip = latestGossip val preferredGossipTargets: Vector[UniqueAddress] = if (ThreadLocalRandom.current.nextDouble() < GossipDifferentViewProbability) { // If it's time to try to gossip to some nodes with a different view // gossip to a random alive member with preference to a member with older or newer gossip version val localMemberAddressesSet = localGossip.members map { _.uniqueAddress } val nodesWithDifferentView = for { (node, version) ← localGossip.overview.seen if localMemberAddressesSet contains node if version != localGossip.version } yield node nodesWithDifferentView.toVector } else Vector.empty[UniqueAddress] if (preferredGossipTargets.nonEmpty) { val peer = selectRandomNode(preferredGossipTargets filterNot (_ == selfUniqueAddress)) // send full gossip because it has different view peer foreach gossipTo } else { // Fall back to localGossip; important to not accidentally use `map` of the SortedSet, since the original order is not preserved) val peer = selectRandomNode(localGossip.members.toIndexedSeq.collect { case m if m.uniqueAddress != selfUniqueAddress ⇒ m.uniqueAddress }) peer foreach { node ⇒ if (localGossip.seenByNode(node)) gossipStatusTo(node) else gossipTo(node) } } } } /** * Runs periodic leader actions, such as member status transitions, auto-downing unreachable nodes, * assigning partitions etc. */ def leaderActions(): Unit = { val localGossip = latestGossip val localMembers = localGossip.members val isLeader = localGossip.isLeader(selfUniqueAddress) if (isLeader && isAvailable) { // only run the leader actions if we are the LEADER and available val localOverview = localGossip.overview val localSeen = localOverview.seen val localUnreachableMembers = localOverview.unreachable val hasPartionHandoffCompletedSuccessfully: Boolean = { // FIXME implement partion handoff and a check if it is completed - now just returns TRUE - e.g. has completed successfully true } // Leader actions are as follows: // 1. Move JOINING => UP -- When a node joins the cluster // 2. Move LEAVING => EXITING -- When all partition handoff has completed // 3. Non-exiting remain -- When all partition handoff has completed // 4. Move EXITING => REMOVED -- When all nodes have seen that the node is EXITING (convergence) - remove the nodes from the node ring and seen table // 5. Move UNREACHABLE => DOWN -- When the node is in the UNREACHABLE set it can be auto-down by leader // 6. Move DOWN => REMOVED -- When all nodes have seen that the node is DOWN (convergence) - remove the nodes from the node ring and seen table // 7. Updating the vclock version for the changes // 8. Updating the `seen` table // 9. Try to update the state with the new gossip // 10. If success - run all the side-effecting processing val ( newGossip: Gossip, hasChangedState: Boolean, upMembers, exitingMembers, removedMembers, removedUnreachableMembers, unreachableButNotDownedMembers) = if (localGossip.convergence) { // we have convergence - so we can't have unreachable nodes def enoughMembers: Boolean = { localMembers.size >= MinNrOfMembers && MinNrOfMembersOfRole.forall { case (role, threshold) ⇒ localMembers.count(_.hasRole(role)) >= threshold } } def isJoiningToUp(m: Member): Boolean = m.status == Joining && enoughMembers // transform the node member ring val newMembers = localMembers collect { // Move JOINING => UP (once all nodes have seen that this node is JOINING, i.e. we have a convergence) // and minimum number of nodes have joined the cluster case member if isJoiningToUp(member) ⇒ member copy (status = Up) // Move LEAVING => EXITING (once we have a convergence on LEAVING // *and* if we have a successful partition handoff) case member if member.status == Leaving && hasPartionHandoffCompletedSuccessfully ⇒ member copy (status = Exiting) // Everyone else that is not Exiting stays as they are case member if member.status != Exiting && member.status != Down ⇒ member // Move EXITING => REMOVED, DOWN => REMOVED - i.e. remove the nodes from the `members` set/node ring and seen table } // ---------------------- // Store away all stuff needed for the side-effecting processing // ---------------------- // Check for the need to do side-effecting on successful state change // Repeat the checking for transitions between JOINING -> UP, LEAVING -> EXITING, EXITING -> REMOVED, DOWN -> REMOVED // to check for state-changes and to store away removed and exiting members for later notification // 1. check for state-changes to update // 2. store away removed and exiting members so we can separate the pure state changes val (removedMembers, newMembers1) = localMembers partition (m ⇒ m.status == Exiting || m.status == Down) val (removedUnreachable, newUnreachable) = localUnreachableMembers partition (_.status == Down) val (upMembers, newMembers2) = newMembers1 partition (isJoiningToUp(_)) val exitingMembers = newMembers2 filter (_.status == Leaving && hasPartionHandoffCompletedSuccessfully) val hasChangedState = removedMembers.nonEmpty || removedUnreachable.nonEmpty || upMembers.nonEmpty || exitingMembers.nonEmpty // removing REMOVED nodes from the `seen` table val newSeen = localSeen -- removedMembers.map(_.uniqueAddress) -- removedUnreachable.map(_.uniqueAddress) val newOverview = localOverview copy (seen = newSeen, unreachable = newUnreachable) // update gossip overview val newGossip = localGossip copy (members = newMembers, overview = newOverview) // update gossip (newGossip, hasChangedState, upMembers, exitingMembers, removedMembers, removedUnreachable, Member.none) } else if (AutoDown) { // we don't have convergence - so we might have unreachable nodes // if 'auto-down' is turned on, then try to auto-down any unreachable nodes val newUnreachableMembers = localUnreachableMembers collect { // ---------------------- // Move UNREACHABLE => DOWN (auto-downing by leader) // ---------------------- case member if member.status != Down ⇒ member copy (status = Down) case downMember ⇒ downMember // no need to DOWN members already DOWN } // Check for the need to do side-effecting on successful state change val unreachableButNotDownedMembers = localUnreachableMembers filter (_.status != Down) // removing nodes marked as DOWN from the `seen` table val newSeen = localSeen -- newUnreachableMembers.collect { case m if m.status == Down ⇒ m.uniqueAddress } val newOverview = localOverview copy (seen = newSeen, unreachable = newUnreachableMembers) // update gossip overview val newGossip = localGossip copy (overview = newOverview) // update gossip (newGossip, unreachableButNotDownedMembers.nonEmpty, Member.none, Member.none, Member.none, Member.none, unreachableButNotDownedMembers) } else (localGossip, false, Member.none, Member.none, Member.none, Member.none, Member.none) if (hasChangedState) { // we have a change of state - version it and try to update // ---------------------- // Updating the vclock version for the changes // ---------------------- val versionedGossip = newGossip :+ vclockNode // ---------------------- // Updating the `seen` table // Unless the leader (this node) is part of the removed members, i.e. the leader have moved himself from EXITING -> REMOVED // ---------------------- val seenVersionedGossip = if (removedMembers.exists(_.uniqueAddress == selfUniqueAddress)) versionedGossip else versionedGossip seen selfUniqueAddress // ---------------------- // Update the state with the new gossip // ---------------------- latestGossip = seenVersionedGossip // ---------------------- // Run all the side-effecting processing // ---------------------- // log the move of members from joining to up upMembers foreach { member ⇒ log.info("Cluster Node [{}] - Leader is moving node [{}] from [{}] to [{}]", selfAddress, member.address, member.status, Up) } // tell all removed members to remove and shut down themselves removedMembers foreach { member ⇒ val address = member.address log.info("Cluster Node [{}] - Leader is moving node [{}] from [{}] to [{}] - and removing node from node ring", selfAddress, address, member.status, Removed) clusterCore(address) ! ClusterLeaderAction.Shutdown(member.uniqueAddress) } // tell all exiting members to exit exitingMembers foreach { member ⇒ val address = member.address log.info("Cluster Node [{}] - Leader is moving node [{}] from [{}] to [{}]", selfAddress, address, member.status, Exiting) clusterCore(address) ! ClusterLeaderAction.Exit(member.uniqueAddress) // FIXME should wait for completion of handoff? } // log the auto-downing of the unreachable nodes unreachableButNotDownedMembers foreach { member ⇒ log.info("Cluster Node [{}] - Leader is marking unreachable node [{}] as [{}]", selfAddress, member.address, Down) } // log the auto-downing of the unreachable nodes removedUnreachableMembers foreach { member ⇒ log.info("Cluster Node [{}] - Leader is removing unreachable node [{}]", selfAddress, member.address) } publish(latestGossip) } } } /** * Reaps the unreachable members (moves them to the `unreachable` list in the cluster overview) according to the failure detector's verdict. */ def reapUnreachableMembers(): Unit = { if (!isSingletonCluster && isAvailable) { // only scrutinize if we are a non-singleton cluster and available val localGossip = latestGossip val localOverview = localGossip.overview val localMembers = localGossip.members val localUnreachableMembers = localGossip.overview.unreachable val newlyDetectedUnreachableMembers = localMembers filterNot { member ⇒ member.uniqueAddress == selfUniqueAddress || member.status == Exiting || failureDetector.isAvailable(member.address) } if (newlyDetectedUnreachableMembers.nonEmpty) { val newMembers = localMembers -- newlyDetectedUnreachableMembers val newUnreachableMembers = localUnreachableMembers ++ newlyDetectedUnreachableMembers val newOverview = localOverview copy (unreachable = newUnreachableMembers) val newGossip = localGossip copy (overview = newOverview, members = newMembers) // updating vclock and `seen` table val versionedGossip = newGossip :+ vclockNode val seenVersionedGossip = versionedGossip seen selfUniqueAddress latestGossip = seenVersionedGossip log.error("Cluster Node [{}] - Marking node(s) as UNREACHABLE [{}]", selfAddress, newlyDetectedUnreachableMembers.mkString(", ")) publish(latestGossip) } } } def selectRandomNode(nodes: IndexedSeq[UniqueAddress]): Option[UniqueAddress] = if (nodes.isEmpty) None else Some(nodes(ThreadLocalRandom.current nextInt nodes.size)) def isSingletonCluster: Boolean = latestGossip.isSingletonCluster def isAvailable: Boolean = !latestGossip.isUnreachable(selfUniqueAddress) // needed for tests def sendGossipTo(address: Address): Unit = { latestGossip.members.foreach(m ⇒ if (m.address == address) gossipTo(m.uniqueAddress)) } /** * Gossips latest gossip to a node. */ def gossipTo(node: UniqueAddress): Unit = if (validNodeForGossip(node)) clusterCore(node.address) ! GossipEnvelope(selfUniqueAddress, node, latestGossip) def gossipTo(node: UniqueAddress, destination: ActorRef): Unit = if (validNodeForGossip(node)) destination ! GossipEnvelope(selfUniqueAddress, node, latestGossip) def gossipStatusTo(node: UniqueAddress, destination: ActorRef): Unit = if (validNodeForGossip(node)) destination ! GossipStatus(selfUniqueAddress, latestGossip.version) def gossipStatusTo(node: UniqueAddress): Unit = if (validNodeForGossip(node)) clusterCore(node.address) ! GossipStatus(selfUniqueAddress, latestGossip.version) def validNodeForGossip(node: UniqueAddress): Boolean = (node != selfUniqueAddress && latestGossip.members.exists(_.uniqueAddress == node)) def publish(newGossip: Gossip): Unit = { publisher ! PublishChanges(newGossip) if (PublishStatsInterval == Duration.Zero) publishInternalStats() } def publishInternalStats(): Unit = publisher ! CurrentInternalStats(stats) } /** * INTERNAL API. * * Used only for the first seed node. * Sends InitJoin to all seed nodes (except itself). * If other seed nodes are not part of the cluster yet they will reply with * InitJoinNack or not respond at all and then the first seed node * will join itself to initialize the new cluster. When the first * seed node is restarted, and some other seed node is part of the cluster * it will reply with InitJoinAck and then the first seed node will join * that other seed node to join existing cluster. */ private[cluster] final class FirstSeedNodeProcess(seedNodes: immutable.IndexedSeq[Address]) extends Actor with ActorLogging { import InternalClusterAction._ import ClusterUserAction.JoinTo val cluster = Cluster(context.system) def selfAddress = cluster.selfAddress if (seedNodes.size <= 1 || seedNodes.head != selfAddress) throw new IllegalArgumentException("Join seed node should not be done") val timeout = Deadline.now + cluster.settings.SeedNodeTimeout var remainingSeedNodes = seedNodes.toSet - selfAddress // retry until one ack, or all nack, or timeout import context.dispatcher val retryTask = cluster.scheduler.schedule(1.second, 1.second, self, JoinSeedNode) self ! JoinSeedNode override def postStop(): Unit = retryTask.cancel() def receive = { case JoinSeedNode ⇒ if (timeout.hasTimeLeft) { // send InitJoin to remaining seed nodes (except myself) remainingSeedNodes foreach { a ⇒ context.actorSelection(context.parent.path.toStringWithAddress(a)) ! InitJoin } } else { // no InitJoinAck received, initialize new cluster by joining myself context.parent ! JoinTo(selfAddress) context.stop(self) } case InitJoinAck(address) ⇒ // first InitJoinAck reply, join existing cluster context.parent ! JoinTo(address) context.stop(self) case InitJoinNack(address) ⇒ remainingSeedNodes -= address if (remainingSeedNodes.isEmpty) { // initialize new cluster by joining myself when nacks from all other seed nodes context.parent ! JoinTo(selfAddress) context.stop(self) } } } /** * INTERNAL API. * * Sends InitJoin to all seed nodes (except itself) and expect * InitJoinAck reply back. The seed node that replied first * will be used, joined to. InitJoinAck replies received after the * first one are ignored. * * Retries if no InitJoinAck replies are received within the * SeedNodeTimeout. * When at least one reply has been received it stops itself after * an idle SeedNodeTimeout. * * The seed nodes can be started in any order, but they will not be "active", * until they have been able to join another seed node (seed1). * They will retry the join procedure. * So one possible startup scenario is: * 1. seed2 started, but doesn't get any ack from seed1 or seed3 * 2. seed3 started, doesn't get any ack from seed1 or seed3 (seed2 doesn't reply) * 3. seed1 is started and joins itself * 4. seed2 retries the join procedure and gets an ack from seed1, and then joins to seed1 * 5. seed3 retries the join procedure and gets acks from seed2 first, and then joins to seed2 * */ private[cluster] final class JoinSeedNodeProcess(seedNodes: immutable.IndexedSeq[Address]) extends Actor with ActorLogging { import InternalClusterAction._ import ClusterUserAction.JoinTo def selfAddress = Cluster(context.system).selfAddress if (seedNodes.isEmpty || seedNodes.head == selfAddress) throw new IllegalArgumentException("Join seed node should not be done") context.setReceiveTimeout(Cluster(context.system).settings.SeedNodeTimeout) override def preStart(): Unit = self ! JoinSeedNode def receive = { case JoinSeedNode ⇒ // send InitJoin to all seed nodes (except myself) seedNodes.collect { case a if a != selfAddress ⇒ context.actorSelection(context.parent.path.toStringWithAddress(a)) } foreach { _ ! InitJoin } case InitJoinAck(address) ⇒ // first InitJoinAck reply context.parent ! JoinTo(address) context.become(done) case InitJoinNack(_) ⇒ // that seed was uninitialized case ReceiveTimeout ⇒ // no InitJoinAck received, try again self ! JoinSeedNode } def done: Actor.Receive = { case InitJoinAck(_) ⇒ // already received one, skip rest case ReceiveTimeout ⇒ context.stop(self) } } /** * INTERNAL API * * The supplied callback will be run, once, when current cluster member is `Up`. */ private[cluster] class OnMemberUpListener(callback: Runnable) extends Actor with ActorLogging { import ClusterEvent._ val cluster = Cluster(context.system) // subscribe to MemberUp, re-subscribe when restart override def preStart(): Unit = cluster.subscribe(self, classOf[MemberUp]) override def postStop(): Unit = cluster.unsubscribe(self) def receive = { case state: CurrentClusterState ⇒ if (state.members.exists(isSelfUp(_))) done() case MemberUp(m) ⇒ if (isSelfUp(m)) done() } def done(): Unit = { try callback.run() catch { case NonFatal(e) ⇒ log.error(e, "OnMemberUp callback failed with [{}]", e.getMessage) } finally { context stop self } } def isSelfUp(m: Member): Boolean = m.uniqueAddress == cluster.selfUniqueAddress && m.status == MemberStatus.Up } /** * INTERNAL API */ @SerialVersionUID(1L) private[cluster] case class ClusterStats( receivedGossipCount: Long = 0L, mergeCount: Long = 0L, sameCount: Long = 0L, newerCount: Long = 0L, olderCount: Long = 0L) { def incrementReceivedGossipCount(): ClusterStats = copy(receivedGossipCount = receivedGossipCount + 1) def incrementMergeCount(): ClusterStats = copy(mergeCount = mergeCount + 1) def incrementSameCount(): ClusterStats = copy(sameCount = sameCount + 1) def incrementNewerCount(): ClusterStats = copy(newerCount = newerCount + 1) def incrementOlderCount(): ClusterStats = copy(olderCount = olderCount + 1) def :+(that: ClusterStats): ClusterStats = { ClusterStats( this.receivedGossipCount + that.receivedGossipCount, this.mergeCount + that.mergeCount, this.sameCount + that.sameCount, this.newerCount + that.newerCount, this.olderCount + that.olderCount) } def :-(that: ClusterStats): ClusterStats = { ClusterStats( this.receivedGossipCount - that.receivedGossipCount, this.mergeCount - that.mergeCount, this.sameCount - that.sameCount, this.newerCount - that.newerCount, this.olderCount - that.olderCount) } }