Packages

class ReliableProxy extends Actor with LoggingFSM[State, Vector[Message]] with ReliableProxyDebugLogging

A ReliableProxy is a means to wrap a remote actor reference in order to obtain certain improved delivery guarantees:

  • as long as the proxy is not terminated before it sends all of its queued messages then no messages will be lost
  • messages re-sent due to the first point will not be delivered out-of-order, message ordering is preserved

These guarantees are valid for the communication between the two end-points of the reliable “tunnel”, which usually spans an unreliable network.

Note that the ReliableProxy guarantees at-least-once, not exactly-once, delivery.

Delivery from the remote end-point to the target actor is still subject to in-JVM delivery semantics (i.e. not strictly guaranteed due to possible OutOfMemory situations or other VM errors).

You can create a reliable connection like this:

In Scala:

val proxy = context.actorOf(ReliableProxy.props(target, 100.millis, 120.seconds)

or in Java:

final ActorRef proxy = getContext().actorOf(ReliableProxy.props(
  target, Duration.create(100, "millis"), Duration.create(120, "seconds")));

Please note: the tunnel is uni-directional, and original sender information is retained, hence replies by the wrapped target reference will go back in the normal “unreliable” way unless also secured by a ReliableProxy from the remote end.

Message Types

This actor is an akka.actor.FSM, hence it offers the service of transition callbacks to those actors which subscribe using the SubscribeTransitionCallBack and UnsubscribeTransitionCallBack messages; see akka.actor.FSM for more documentation. The proxy will transition into ReliableProxy.Active state when ACKs are outstanding and return to the ReliableProxy.Idle state when every message send so far has been confirmed by the peer end-point.

The initial state of the proxy is ReliableProxy.Connecting. In this state the proxy will repeatedly send akka.actor.Identify messages to ActorSelection(targetPath) in order to obtain a new ActorRef for the target. When an akka.actor.ActorIdentity for the target is received a new tunnel will be created, a ReliableProxy.TargetChanged message containing the target ActorRef will be sent to the proxy's transition subscribers and the proxy will transition into either the ReliableProxy.Idle or ReliableProxy.Active state, depending if there are any outstanding messages that need to be delivered. If maxConnectAttempts is defined this actor will stop itself after Identify is sent maxConnectAttempts times.

While in the Idle or Active states, if a communication failure causes the tunnel to terminate via Remote Deathwatch the proxy will transition into the ReliableProxy.Connecting state as described above. After reconnecting TargetChanged will be sent only if the target ActorRef has changed.

If this actor is stopped and it still has outstanding messages a ReliableProxy.ProxyTerminated message will be sent to the transition subscribers. It contains an Unsent object with the outstanding messages.

If an ReliableProxy.Unsent message is sent to this actor the messages contained within it will be relayed through the tunnel to the target.

Any other message type sent to this actor will be delivered via a remote-deployed child actor to the designated target.

Failure Cases

All failures of either the local or the remote end-point are escalated to the parent of this actor; there are no specific error cases which are predefined.

Arguments

See the constructor below for the arguments for this actor. However, prefer using akka.contrib.pattern.ReliableProxy#props to this actor's constructor.

Annotations
@deprecated
Deprecated

(Since version 2.5.0) Use AtLeastOnceDelivery instead

Source
ReliableProxy.scala
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  1. ReliableProxy
  2. ReliableProxyDebugLogging
  3. LoggingFSM
  4. FSM
  5. ActorLogging
  6. Listeners
  7. Actor
  8. AnyRef
  9. Any
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Instance Constructors

  1. new ReliableProxy(targetPath: ActorPath, retryAfter: FiniteDuration, reconnectAfter: Option[FiniteDuration], maxConnectAttempts: Option[Int])

    targetPath

    is the ActorPath to the actor to which all messages will be forwarded. targetPath can point to a local or remote actor, but the tunnel endpoint will be deployed remotely on the node where the target actor lives.

    retryAfter

    is the ACK timeout after which all outstanding messages will be resent. There is no limit on the queue size or the number of retries.

    reconnectAfter

     is an optional interval between connection attempts. It is also used as the interval between receiving a Terminated for the tunnel and attempting to reconnect to the target actor. The minimum recommended value for this is the value of the configuration setting akka.remote.retry-gate-closed-for. Use None to never reconnect after a disconnection.

    maxConnectAttempts

     is an optional maximum number of attempts to connect to the target actor. Use None for no limit. If reconnectAfter is None this value is ignored.

Type Members

  1. final class TransformHelper extends AnyRef
    Definition Classes
    FSM
  2. type Event = actor.FSM.Event[Vector[Message]]
    Definition Classes
    FSM
  3. type Receive = PartialFunction[Any, Unit]
    Definition Classes
    Actor
  4. type State = actor.FSM.State[ReliableProxy.State, Vector[Message]]
    Definition Classes
    FSM
  5. type StateFunction = PartialFunction[Event, State]
    Definition Classes
    FSM
  6. type StopEvent = actor.FSM.StopEvent[ReliableProxy.State, Vector[Message]]
    Definition Classes
    FSM
  7. type Timeout = Option[FiniteDuration]
    Definition Classes
    FSM
  8. type TransitionHandler = PartialFunction[(ReliableProxy.State, ReliableProxy.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 addSelf(template: String): String
    Definition Classes
    ReliableProxyDebugLogging
  6. var attemptedReconnects: Int
  7. 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
  8. 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
  9. def createTunnel(target: ActorRef): Unit
  10. var currentSerial: Int
  11. var currentTarget: ActorRef
  12. val debug: Boolean
    Definition Classes
    ReliableProxyDebugLogging
  13. val defaultConnectInterval: FiniteDuration
  14. def enabled: Boolean
    Definition Classes
    ReliableProxyDebugLogging
  15. final def goto(nextStateName: ReliableProxy.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
  16. val initialState: Connecting.type
  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. var lastAckSerial: Int
  20. def log: LoggingAdapter
    Definition Classes
    ActorLogging
  21. def logDebug(template: String, arg1: Any): Unit
    Definition Classes
    ReliableProxyDebugLogging
  22. def logDebug(template: String, arg1: Any, arg2: Any): Unit
    Definition Classes
    ReliableProxyDebugLogging
  23. def logDepth: Int
    Definition Classes
    LoggingFSM
  24. def logResend(size: Int): Unit
  25. def nextBackoff(): FiniteDuration

    Returns the next retry interval duration.

    Returns the next retry interval duration. By default each interval is the same, reconnectAfter.

  26. def nextSerial(): Int
  27. final def nextStateData: Vector[Message]

    Return next state data (available in onTransition handlers)

    Return next state data (available in onTransition handlers)

    Definition Classes
    FSM
  28. 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
  29. 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
  30. 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] )
  31. 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
    ReliableProxyFSMActor
  32. 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] )
  33. 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
    Actor
    Annotations
    @throws( classOf[Exception] )
  34. 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
    FSMActor
  35. val reconnectTimer: String
  36. def resend(q: Vector[Message]): Vector[Message]
  37. val resendTimer: String
  38. def resetBackoff(): Unit

    Reset backoff interval.

    Reset backoff interval.

    This and nextBackoff are meant to be implemented by subclasses.

  39. val retryGateClosedFor: Long
  40. def scheduleReconnectTick(): Unit
  41. def scheduleTick(): Unit
  42. 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
  43. def send(msg: Any, snd: ActorRef): Message
  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: ReliableProxy.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: ReliableProxy.State, stateData: Vector[Message], 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: Vector[Message]

    Return current state data (i.e.

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

    Definition Classes
    FSM
  49. final def stateName: ReliableProxy.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: Vector[Message]): 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: OneForOneStrategy

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

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

    Definition Classes
    ReliableProxyActor
  55. def terminated(): State
  56. def toParArray: ParArray[T]
    Implicit
    This member is added by an implicit conversion from ReliableProxy to CollectionsHaveToParArray[ReliableProxy, T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (ReliableProxy) ⇒ GenTraversableOnce[T] is in scope.
    Definition Classes
    CollectionsHaveToParArray
  57. implicit final def total2pf(transitionHandler: (ReliableProxy.State, ReliableProxy.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
  58. final def transform(func: StateFunction): TransformHelper
    Definition Classes
    FSM
  59. var tunnel: ActorRef
  60. 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
  61. def updateSerial(q: Vector[Message]): Vector[Message]
  62. final def when(stateName: ReliableProxy.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
  63. 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