FSM

All Superinterfaces:

Actor, ActorLogging, Listeners

All Known Subinterfaces:

LoggingFSM<S,D>

All Known Implementing Classes:

AbstractFSM, AbstractFSMWithStash, AbstractLoggingFSM, BarrierCoordinator, CircuitBreakerProxy, ClientFSM, ClusterSingletonManager, ProtocolStateActor, ReliableProxy, ServerFSM, ThrottledAssociation, TimerBasedThrottler
```
public interface FSM<S,D>
extends Actor, Listeners, ActorLogging
```
Finite State Machine actor trait. Use as follows:
```
   object A {
     trait State
     case class One extends State
     case class Two extends State

     case class Data(i : Int)
   }

   class A extends Actor with FSM[A.State, A.Data] {
     import A._

     startWith(One, Data(42))
     when(One) {
         case Event(SomeMsg, Data(x)) => ...
         case Ev(SomeMsg) => ... // convenience when data not needed
     }
     when(Two, stateTimeout = 5 seconds) { ... }
     initialize()
   }
 
```
Within the partial function the following values are returned for effecting state transitions:
- stay for staying in the same state - stay using Data(...) for staying in the same state, but with different data - stay forMax 5.millis for staying with a state timeout; can be combined with using - goto(...) for changing into a different state; also supports using and forMax - stop for terminating this FSM actor
Each of the above also supports the method replying(AnyRef) for sending a reply before changing state.
While changing state, custom handlers may be invoked which are registered using onTransition. This is meant to enable concentrating different concerns in different places; you may choose to use when for describing the properties of a state, including of course initiating transitions, but you can describe the transitions using onTransition to avoid having to duplicate that code among multiple paths which lead to a transition:
```
 onTransition {
   case Active -&gt; _ =&gt; cancelTimer("activeTimer")
 }
 
```
Multiple such blocks are supported and all of them will be called, not only the first matching one.
Another feature is that other actors may subscribe for transition events by sending a SubscribeTransitionCallback message to this actor. Stopping a listener without unregistering will not remove the listener from the subscription list; use UnsubscribeTransitionCallback before stopping the listener.
State timeouts set an upper bound to the time which may pass before another message is received in the current state. If no external message is available, then upon expiry of the timeout a StateTimeout message is sent. Note that this message will only be received in the state for which the timeout was set and that any message received will cancel the timeout (possibly to be started again by the next transition).
Another feature is the ability to install and cancel single-shot as well as repeated timers which arrange for the sending of a user-specified message:
```
   setTimer("tock", TockMsg, 1 second, true) // repeating
   setTimer("lifetime", TerminateMsg, 1 hour, false) // single-shot
   cancelTimer("tock")
   isTimerActive("tock")
 
```

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static class`	`FSM.$minus$greater$` This extractor is just convenience for matching a (S, S) pair, including a reminder what the new state is.
`static class`	`FSM.CurrentState<S>` Message type which is sent directly to the subscribed actor in `FSM.SubscribeTransitionCallBack` before sending any `FSM.Transition` messages.
`static class`	`FSM.CurrentState$`
`static class`	`FSM.Event<D>` All messages sent to the `FSM` will be wrapped inside an `Event`, which allows pattern matching to extract both state and data.
`static class`	`FSM.Event$`
`static class`	`FSM.Failure` Signifies that the `FSM` is shutting itself down because of an error, e.g.
`static class`	`FSM.Failure$`
`static class`	`FSM.LogEntry<S,D>` Log Entry of the `LoggingFSM`, can be obtained by calling `getLog`.
`static class`	`FSM.LogEntry$`
`static class`	`FSM.Normal$` Default reason if calling `stop()`.
`static class`	`FSM.NullFunction$` A partial function value which does not match anything and can be used to “reset” `whenUnhandled` and `onTermination` handlers.
`static interface`	`FSM.Reason` Reason why this `FSM` is shutting down.
`static class`	`FSM.Shutdown$` Reason given when someone was calling `system.stop(fsm)` from outside; also applies to `Stop` supervision directive.
`static class`	`FSM.SilentState<S,D>` INTERNAL API Using a subclass for binary compatibility reasons
`static class`	`FSM.State<S,D>` This captures all of the managed state of the `FSM`: the state name, the state data, possibly custom timeout, stop reason and replies accumulated while processing the last message.
`static class`	`FSM.State$`
`static class`	`FSM.StateTimeout$` This case object is received in case of a state timeout.
`static class`	`FSM.StopEvent<S,D>` Case class representing the state of the `FSM` within the `onTermination` block.
`static class`	`FSM.StopEvent$`
`static class`	`FSM.SubscribeTransitionCallBack` Send this to an `FSM` to request first the `FSM.CurrentState` and then a series of `FSM.Transition` updates.
`static class`	`FSM.SubscribeTransitionCallBack$`
`static class`	`FSM.TimeoutMarker` INTERNAL API
`static class`	`FSM.TimeoutMarker$`
`static class`	`FSM.Timer` INTERNAL API
`static class`	`FSM.Timer$`
`static class`	`FSM.TransformHelper`
`static class`	`FSM.Transition<S>` Message type which is used to communicate transitions between states to all subscribed listeners (use `FSM.SubscribeTransitionCallBack`).
`static class`	`FSM.Transition$`
`static class`	`FSM.UnsubscribeTransitionCallBack` Unsubscribe from `FSM.Transition` notifications which was effected by sending the corresponding `FSM.SubscribeTransitionCallBack`.
`static class`	`FSM.UnsubscribeTransitionCallBack$`

Nested classes/interfaces inherited from interface akka.actor.Actor
Actor.emptyBehavior$, Actor.ignoringBehavior$

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`applyState(FSM.State<S,D> nextState)`
`void`	`cancelTimer(java.lang.String name)`
`boolean`	`debugEvent()`
`FSM.Event$`	`Event()`
`void`	`handleTransition(S prev, S next)`
`void`	`initialize()`
`boolean`	`isStateTimerActive()`
`boolean`	`isTimerActive(java.lang.String name)`
`void`	`logTermination(FSM.Reason reason)` By default `FSM.Failure` is logged at error level and other reason types are not logged.
`void`	`makeTransition(FSM.State<S,D> nextState)`
`D`	`nextStateData()`
`void`	`onTermination(scala.PartialFunction<FSM.StopEvent<S,D>,scala.runtime.BoxedUnit> terminationHandler)`
`void`	`onTransition(scala.PartialFunction<scala.Tuple2<S,S>,scala.runtime.BoxedUnit> transitionHandler)`
`void`	`postStop()` User overridable callback.
`void`	`processEvent(FSM.Event<D> event, java.lang.Object source)`
`void`	`processMsg(java.lang.Object value, java.lang.Object source)`
`scala.PartialFunction<java.lang.Object,scala.runtime.BoxedUnit>`	`receive()` This defines the initial actor behavior, it must return a partial function with the actor logic.
`void`	`register(S name, scala.PartialFunction<FSM.Event<D>,FSM.State<S,D>> function, scala.Option<scala.concurrent.duration.FiniteDuration> timeout)`
`void`	`setStateTimeout(S state, scala.Option<scala.concurrent.duration.FiniteDuration> timeout)`
`void`	`setTimer(java.lang.String name, java.lang.Object msg, scala.concurrent.duration.FiniteDuration timeout, boolean repeat)`
`void`	`startWith(S stateName, D stateData, scala.Option<scala.concurrent.duration.FiniteDuration> timeout)` Set initial state.
`D`	`stateData()`
`S`	`stateName()`
`FSM.StateTimeout$`	`StateTimeout()` This case object is received in case of a state timeout.
`FSM.State<S,D>`	`stay()` Produce "empty" transition descriptor.
`FSM.State<S,D>`	`stop()` Produce change descriptor to stop this FSM actor with reason "Normal".
`FSM.State<S,D>`	`stop(FSM.Reason reason)` Produce change descriptor to stop this FSM actor including specified reason.
`FSM.State<S,D>`	`stop(FSM.Reason reason, D stateData)` Produce change descriptor to stop this FSM actor including specified reason.
`FSM.StopEvent$`	`StopEvent()`
`void`	`terminate(FSM.State<S,D> nextState)`
`scala.PartialFunction<scala.Tuple2<S,S>,scala.runtime.BoxedUnit>`	`total2pf(scala.Function2<S,S,scala.runtime.BoxedUnit> transitionHandler)`
`FSM.TransformHelper`	`transform(scala.PartialFunction<FSM.Event<D>,FSM.State<S,D>> func)`
`void`	`when(S stateName, scala.concurrent.duration.FiniteDuration stateTimeout, scala.PartialFunction<FSM.Event<D>,FSM.State<S,D>> stateFunction)` Insert a new StateFunction at the end of the processing chain for the given state.
`void`	`whenUnhandled(scala.PartialFunction<FSM.Event<D>,FSM.State<S,D>> stateFunction)`

Methods inherited from interface akka.actor.Actor
aroundPostRestart, aroundPostStop, aroundPreRestart, aroundPreStart, aroundReceive, context, postRestart, preRestart, preStart, self, sender, supervisorStrategy, unhandled

Methods inherited from interface akka.routing.Listeners
gossip, listenerManagement, listeners

Methods inherited from interface akka.actor.ActorLogging
log

- Method Detail
  - Event
```
FSM.Event$ Event()
```
  - StopEvent
```
FSM.StopEvent$ StopEvent()
```
  - StateTimeout
```
FSM.StateTimeout$ StateTimeout()
```
    This case object is received in case of a state timeout.
    
    Returns:
    
    (undocumented)
  - when
```
void when(S stateName,
          scala.concurrent.duration.FiniteDuration stateTimeout,
          scala.PartialFunction<FSM.Event<D>,FSM.State<S,D>> stateFunction)
```
    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.
    
    Parameters:
    
    stateName - designator for the state
    
    stateTimeout - default state timeout for this state
    
    stateFunction - partial function describing response to input
  - startWith
```
void startWith(S stateName,
               D stateData,
               scala.Option<scala.concurrent.duration.FiniteDuration> timeout)
```
    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 Actor.preStart() and Actor.postRestart(java.lang.Throwable).
    
    Parameters:
    
    stateName - initial state designator
    
    stateData - initial state data
    
    timeout - state timeout for the initial state, overriding the default timeout for that state
  - stay
```
FSM.State<S,D> stay()
```
    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
  - stop
```
FSM.State<S,D> stop()
```
    Produce change descriptor to stop this FSM actor with reason "Normal".
    
    Returns:
    
    (undocumented)
  - stop
```
FSM.State<S,D> stop(FSM.Reason reason)
```
    Produce change descriptor to stop this FSM actor including specified reason.
    
    Parameters:
    
    reason - (undocumented)
    
    Returns:
    
    (undocumented)
  - stop
```
FSM.State<S,D> stop(FSM.Reason reason,
                    D stateData)
```
    Produce change descriptor to stop this FSM actor including specified reason.
    
    Parameters:
    
    reason - (undocumented)
    
    stateData - (undocumented)
    
    Returns:
    
    (undocumented)
  - transform
```
FSM.TransformHelper transform(scala.PartialFunction<FSM.Event<D>,FSM.State<S,D>> func)
```
  - setTimer
```
void setTimer(java.lang.String name,
              java.lang.Object msg,
              scala.concurrent.duration.FiniteDuration timeout,
              boolean repeat)
```
  - cancelTimer
```
void cancelTimer(java.lang.String name)
```
  - isTimerActive
```
boolean isTimerActive(java.lang.String name)
```
  - setStateTimeout
```
void setStateTimeout(S state,
                     scala.Option<scala.concurrent.duration.FiniteDuration> timeout)
```
  - isStateTimerActive
```
boolean isStateTimerActive()
```
  - onTransition
```
void onTransition(scala.PartialFunction<scala.Tuple2<S,S>,scala.runtime.BoxedUnit> transitionHandler)
```
  - total2pf
```
scala.PartialFunction<scala.Tuple2<S,S>,scala.runtime.BoxedUnit> total2pf(scala.Function2<S,S,scala.runtime.BoxedUnit> transitionHandler)
```
  - onTermination
```
void onTermination(scala.PartialFunction<FSM.StopEvent<S,D>,scala.runtime.BoxedUnit> terminationHandler)
```
  - whenUnhandled
```
void whenUnhandled(scala.PartialFunction<FSM.Event<D>,FSM.State<S,D>> stateFunction)
```
  - initialize
```
void initialize()
```
  - stateName
```
S stateName()
```
  - stateData
```
D stateData()
```
  - nextStateData
```
D nextStateData()
```
  - debugEvent
```
boolean debugEvent()
```
  - register
```
void register(S name,
              scala.PartialFunction<FSM.Event<D>,FSM.State<S,D>> function,
              scala.Option<scala.concurrent.duration.FiniteDuration> timeout)
```
  - handleTransition
```
void handleTransition(S prev,
                      S next)
```
  - receive
```
scala.PartialFunction<java.lang.Object,scala.runtime.BoxedUnit> receive()
```
    Description copied from interface: Actor
    
    This defines the initial actor behavior, it must return a partial function with the actor logic.
    
    Specified by:
    
    receive in interface Actor
    
    Returns:
    
    (undocumented)
  - processMsg
```
void processMsg(java.lang.Object value,
                java.lang.Object source)
```
  - processEvent
```
void processEvent(FSM.Event<D> event,
                  java.lang.Object source)
```
  - applyState
```
void applyState(FSM.State<S,D> nextState)
```
  - makeTransition
```
void makeTransition(FSM.State<S,D> nextState)
```
  - postStop
```
void postStop()
```
    Description copied from interface: Actor
    
    User overridable callback.
    Is called asynchronously after 'actor.stop()' is invoked. Empty default implementation.
    
    Specified by:
    
    postStop in interface Actor
  - terminate
```
void terminate(FSM.State<S,D> nextState)
```
  - logTermination
```
void logTermination(FSM.Reason reason)
```
    By default FSM.Failure is logged at error level and other reason types are not logged. It is possible to override this behavior.
    
    Parameters:
    
    reason - (undocumented)

Interface FSM<S,D>

Nested Class Summary

Nested classes/interfaces inherited from interface akka.actor.Actor

Method Summary

Methods inherited from interface akka.actor.Actor

Methods inherited from interface akka.routing.Listeners

Methods inherited from interface akka.actor.ActorLogging

Method Detail

Event

StopEvent

StateTimeout

when

startWith

stay

stop

stop

stop

transform

setTimer

cancelTimer

isTimerActive

setStateTimeout

isStateTimerActive

onTransition

total2pf

onTermination

whenUnhandled

initialize

stateName

stateData

nextStateData

debugEvent

register

handleTransition

receive

processMsg

processEvent

applyState

makeTransition

postStop

terminate

logTermination