Packages

class ClusterSingletonManager extends Actor with FSM[State, Data]

Manages singleton actor instance among all cluster nodes or a group of nodes tagged with a specific role. At most one singleton instance is running at any point in time.

The ClusterSingletonManager is supposed to be started on all nodes, or all nodes with specified role, in the cluster with actorOf. The actual singleton is started on the oldest node by creating a child actor from the supplied singletonProps.

The singleton actor is always running on the oldest member with specified role. The oldest member is determined by akka.cluster.Member#isOlderThan. This can change when removing members. A graceful hand over can normally be performed when current oldest node is leaving the cluster. Be aware that there is a short time period when there is no active singleton during the hand-over process.

The cluster failure detector will notice when oldest node becomes unreachable due to things like JVM crash, hard shut down, or network failure. When the crashed node has been removed (via down) from the cluster then a new oldest node will take over and a new singleton actor is created. For these failure scenarios there will not be a graceful hand-over, but more than one active singletons is prevented by all reasonable means. Some corner cases are eventually resolved by configurable timeouts.

You access the singleton actor with ClusterSingletonProxy. Alternatively the singleton actor may broadcast its existence when it is started.

Use factory method ClusterSingletonManager#props to create the akka.actor.Props for the actor.

Not intended for subclassing by user code.

Annotations
@DoNotInherit()
Source
ClusterSingletonManager.scala
Linear Supertypes
FSM[ClusterSingletonManager.State, Data], ActorLogging, Listeners, Actor, AnyRef, Any
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  1. ClusterSingletonManager
  2. FSM
  3. ActorLogging
  4. Listeners
  5. Actor
  6. AnyRef
  7. Any
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  2. by StringFormat
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Instance Constructors

  1. new ClusterSingletonManager(singletonProps: Props, terminationMessage: Any, settings: ClusterSingletonManagerSettings)

    singletonProps

    akka.actor.Props of the singleton actor instance.

    terminationMessage

    When handing over to a new oldest node this terminationMessage is sent to the singleton actor to tell it to finish its work, close resources, and stop. The hand-over to the new oldest node is completed when the singleton actor is terminated. Note that akka.actor.PoisonPill is a perfectly fine terminationMessage if you only need to stop the actor.

    settings

    see ClusterSingletonManagerSettings

Type Members

  1. final class TransformHelper extends AnyRef
    Definition Classes
    FSM
  2. type Event = actor.FSM.Event[Data]
    Definition Classes
    FSM
  3. type Receive = PartialFunction[Any, Unit]
    Definition Classes
    Actor
  4. type State = actor.FSM.State[ClusterSingletonManager.State, Data]
    Definition Classes
    FSM
  5. type StateFunction = PartialFunction[Event, State]
    Definition Classes
    FSM
  6. type StopEvent = actor.FSM.StopEvent[ClusterSingletonManager.State, Data]
    Definition Classes
    FSM
  7. type Timeout = Option[FiniteDuration]
    Definition Classes
    FSM
  8. type TransitionHandler = PartialFunction[(ClusterSingletonManager.State, ClusterSingletonManager.State), Unit]
    Definition Classes
    FSM

Value Members

  1. val ->: actor.FSM.->.type

    This extractor is just convenience for matching a (S, S) pair, including a reminder what the new state is.

    This extractor is just convenience for matching a (S, S) pair, including a reminder what the new state is.

    Definition Classes
    FSM
  2. val Event: actor.FSM.Event.type
    Definition Classes
    FSM
  3. val StateTimeout: actor.FSM.StateTimeout.type

    This case object is received in case of a state timeout.

    This case object is received in case of a state timeout.

    Definition Classes
    FSM
  4. val StopEvent: actor.FSM.StopEvent.type
    Definition Classes
    FSM
  5. def addRemoved(node: UniqueAddress): Unit
  6. final def cancelTimer(name: String): Unit

    Cancel named timer, ensuring that the message is not subsequently delivered (no race).

    Cancel named timer, ensuring that the message is not subsequently delivered (no race).

    name

    of the timer to cancel

    Definition Classes
    FSM
  7. def cleanupOverdueNotMemberAnyMore(): Unit
  8. val cluster: Cluster
  9. implicit val context: ActorContext

    Scala API: Stores the context for this actor, including self, and sender.

    Scala API: Stores the context for this actor, including self, and sender. It is implicit to support operations such as forward.

    WARNING: Only valid within the Actor itself, so do not close over it and publish it to other threads!

    akka.actor.ActorContext is the Scala API. getContext returns a akka.actor.AbstractActor.ActorContext, which is the Java API of the actor context.

    Definition Classes
    Actor
  10. val coordShutdown: CoordinatedShutdown
  11. def getNextOldestChanged(): Unit
  12. final def goto(nextStateName: ClusterSingletonManager.State): State

    Produce transition to other state.

    Produce transition to other state. Return this from a state function in order to effect the transition.

    This method always triggers transition events, even for A -> A transitions. If you want to stay in the same state without triggering an state transition event use #stay instead.

    nextStateName

    state designator for the next state

    returns

    state transition descriptor

    Definition Classes
    FSM
  13. def gotoHandingOver(singleton: ActorRef, singletonTerminated: Boolean, handOverTo: Option[ActorRef]): State
  14. def gotoOldest(): State
  15. def gotoStopping(singleton: ActorRef): State
  16. def handOverDone(handOverTo: Option[ActorRef]): State
  17. final def initialize(): Unit

    Verify existence of initial state and setup timers.

    Verify existence of initial state and setup timers. This should be the last call within the constructor, or akka.actor.Actor#preStart and akka.actor.Actor#postRestart

    An initial currentState -> currentState notification will be triggered by calling this method.

    Definition Classes
    FSM
    See also

    #startWith

  18. final def isTimerActive(name: String): Boolean

    Inquire whether the named timer is still active.

    Inquire whether the named timer is still active. Returns true unless the timer does not exist, has previously been canceled or if it was a single-shot timer whose message was already received.

    Definition Classes
    FSM
  19. def log: LoggingAdapter
    Definition Classes
    ActorLogging
  20. def logInfo(template: String, arg1: Any, arg2: Any): Unit
  21. def logInfo(template: String, arg1: Any): Unit
  22. def logInfo(message: String): Unit
  23. val maxHandOverRetries: Int
  24. val maxTakeOverRetries: Int
  25. val memberExitingProgress: Promise[Done]
  26. final def nextStateData: Data

    Return next state data (available in onTransition handlers)

    Return next state data (available in onTransition handlers)

    Definition Classes
    FSM
  27. var oldestChangedBuffer: ActorRef
  28. var oldestChangedReceived: Boolean
  29. final def onTermination(terminationHandler: PartialFunction[StopEvent, Unit]): Unit

    Set handler which is called upon termination of this FSM actor.

    Set handler which is called upon termination of this FSM actor. Calling this method again will overwrite the previous contents.

    Definition Classes
    FSM
  30. final def onTransition(transitionHandler: TransitionHandler): Unit

    Set handler which is called upon each state transition, i.e.

    Set handler which is called upon each state transition, i.e. not when staying in the same state. This may use the pair extractor defined in the FSM companion object like so:

    onTransition {
  case Old -> New => doSomething
}

    It is also possible to supply a 2-ary function object:

    onTransition(handler _)

private def handler(from: S, to: S) { ... }

    The underscore is unfortunately necessary to enable the nicer syntax shown above (it uses the implicit conversion total2pf under the hood).

    Multiple handlers may be installed, and every one of them will be called, not only the first one matching.

    Definition Classes
    FSM
  31. def peer(at: Address): ActorSelection
  32. def postRestart(reason: Throwable): Unit

    User overridable callback: By default it calls preStart().

    User overridable callback: By default it calls preStart().

    reason

    the Throwable that caused the restart to happen Is called right AFTER restart on the newly created Actor to allow reinitialization after an Actor crash.

    Definition Classes
    Actor
    Annotations
    @throws( classOf[Exception] )
  33. def postStop(): Unit

    Call onTermination hook; if you want to retain this behavior when overriding make sure to call super.postStop().

    Call onTermination hook; if you want to retain this behavior when overriding make sure to call super.postStop().

    Please note that this method is called by default from preRestart(), so override that one if onTermination shall not be called during restart.

    Definition Classes
    ClusterSingletonManager → FSM → Actor
  34. def preRestart(reason: Throwable, message: Option[Any]): Unit

    Scala API: User overridable callback: By default it disposes of all children and then calls postStop().

    Scala API: User overridable callback: By default it disposes of all children and then calls postStop().

    reason

    the Throwable that caused the restart to happen

    message

    optionally the current message the actor processed when failing, if applicable Is called on a crashed Actor right BEFORE it is restarted to allow clean up of resources before Actor is terminated.

    Definition Classes
    Actor
    Annotations
    @throws( classOf[Exception] )
  35. def preStart(): Unit

    User overridable callback.

    User overridable callback.

    Is called when an Actor is started. Actors are automatically started asynchronously when created. Empty default implementation.

    Definition Classes
    ClusterSingletonManager → Actor
  36. def receive: Receive

    Scala API: This defines the initial actor behavior, it must return a partial function with the actor logic.

    Scala API: This defines the initial actor behavior, it must return a partial function with the actor logic.

    Definition Classes
    FSM → Actor
  37. val removalMargin: FiniteDuration
  38. var removed: Map[UniqueAddress, Deadline]
  39. def scheduleDelayedMemberRemoved(m: Member): Unit
  40. implicit final val self: ActorRef

    The 'self' field holds the ActorRef for this actor.

    The 'self' field holds the ActorRef for this actor.

    Can be used to send messages to itself: 

    self ! message

    Definition Classes
    Actor
  41. var selfExited: Boolean
  42. def selfMemberExited(): Unit
  43. val selfUniqueAddressOption: Some[UniqueAddress]
  44. final def sender(): ActorRef

    The reference sender Actor of the last received message.

    The reference sender Actor of the last received message. Is defined if the message was sent from another Actor, else deadLetters in akka.actor.ActorSystem.

    WARNING: Only valid within the Actor itself, so do not close over it and publish it to other threads!

    Definition Classes
    Actor
  45. final def setStateTimeout(state: ClusterSingletonManager.State, timeout: Timeout): Unit

    Set state timeout explicitly.

    Set state timeout explicitly. This method can safely be used from within a state handler.

    Definition Classes
    FSM
  46. final def setTimer(name: String, msg: Any, timeout: FiniteDuration, repeat: Boolean = false): Unit

    Schedule named timer to deliver message after given delay, possibly repeating.

    Schedule named timer to deliver message after given delay, possibly repeating. Any existing timer with the same name will automatically be canceled before adding the new timer.

    name

    identifier to be used with cancelTimer()

    msg

    message to be delivered

    timeout

    delay of first message delivery and between subsequent messages

    repeat

    send once if false, scheduleAtFixedRate if true

    Definition Classes
    FSM
  47. final def startWith(stateName: ClusterSingletonManager.State, stateData: Data, timeout: Timeout = None): Unit

    Set initial state.

    Set initial state. Call this method from the constructor before the #initialize method. If different state is needed after a restart this method, followed by #initialize, can be used in the actor life cycle hooks akka.actor.Actor#preStart and akka.actor.Actor#postRestart.

    stateName

    initial state designator

    stateData

    initial state data

    timeout

    state timeout for the initial state, overriding the default timeout for that state

    Definition Classes
    FSM
  48. final def stateData: Data

    Return current state data (i.e.

    Return current state data (i.e. object of type D)

    Definition Classes
    FSM
  49. final def stateName: ClusterSingletonManager.State

    Return current state name (i.e.

    Return current state name (i.e. object of type S)

    Definition Classes
    FSM
  50. final def stay(): State

    Produce "empty" transition descriptor.

    Produce "empty" transition descriptor. Return this from a state function when no state change is to be effected.

    No transition event will be triggered by #stay. If you want to trigger an event like S -> S for onTransition to handle use goto instead.

    returns

    descriptor for staying in current state

    Definition Classes
    FSM
  51. final def stop(reason: Reason, stateData: Data): State

    Produce change descriptor to stop this FSM actor including specified reason.

    Produce change descriptor to stop this FSM actor including specified reason.

    Definition Classes
    FSM
  52. final def stop(reason: Reason): State

    Produce change descriptor to stop this FSM actor including specified reason.

    Produce change descriptor to stop this FSM actor including specified reason.

    Definition Classes
    FSM
  53. final def stop(): State

    Produce change descriptor to stop this FSM actor with reason "Normal".

    Produce change descriptor to stop this FSM actor with reason "Normal".

    Definition Classes
    FSM
  54. def supervisorStrategy: SupervisorStrategy

    User overridable definition the strategy to use for supervising child actors.

    User overridable definition the strategy to use for supervising child actors.

    Definition Classes
    Actor
  55. implicit final def total2pf(transitionHandler: (ClusterSingletonManager.State, ClusterSingletonManager.State) ⇒ Unit): TransitionHandler

    Convenience wrapper for using a total function instead of a partial function literal.

    Convenience wrapper for using a total function instead of a partial function literal. To be used with onTransition.

    Definition Classes
    FSM
  56. final def transform(func: StateFunction): TransformHelper
    Definition Classes
    FSM
  57. def unhandled(message: Any): Unit

    User overridable callback.

    User overridable callback.

    Is called when a message isn't handled by the current behavior of the actor by default it fails with either a akka.actor.DeathPactException (in case of an unhandled akka.actor.Terminated message) or publishes an akka.actor.UnhandledMessage to the actor's system's akka.event.EventStream

    Definition Classes
    Actor
  58. final def when(stateName: ClusterSingletonManager.State, stateTimeout: FiniteDuration = null)(stateFunction: StateFunction): Unit

    Insert a new StateFunction at the end of the processing chain for the given state.

    Insert a new StateFunction at the end of the processing chain for the given state. If the stateTimeout parameter is set, entering this state without a differing explicit timeout setting will trigger a StateTimeout event; the same is true when using #stay.

    stateName

    designator for the state

    stateTimeout

    default state timeout for this state

    stateFunction

    partial function describing response to input

    Definition Classes
    FSM
  59. final def whenUnhandled(stateFunction: StateFunction): Unit

    Set handler which is called upon reception of unhandled messages.

    Set handler which is called upon reception of unhandled messages. Calling this method again will overwrite the previous contents.

    The current state may be queried using stateName.

    Definition Classes
    FSM