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.
This case object is received in case of a state timeout.
This case object is received in case of a state timeout.
Can be overridden to intercept calls to postRestart
.
Can be overridden to intercept calls to postStop
.
Can be overridden to intercept calls to preRestart
.
Can be overridden to intercept calls to preStart
.
INTERNAL API.
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).
of the timer to cancel
Stores the context for this actor, including self, and sender.
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.UntypedActorContext, which is the Java API of the actor
context.
Sends the supplied message to all current listeners using the provided sender() as sender.
Sends the supplied message to all current listeners using the provided sender() as sender.
Produce transition to other state.
Produce transition to other state. Return this from a state function in order to effect the transition.
state designator for the next state
state transition descriptor
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
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.
Chain this into the receive function.
Chain this into the receive function.
def receive = listenerManagement orElse
By default FSM.Failure is logged at error level and other reason types are not logged.
By default FSM.Failure is logged at error level and other reason types are not logged. It is possible to override this behavior.
Return next state data (available in onTransition handlers)
Return next state data (available in onTransition handlers)
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.
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.
User overridable callback: By default it calls preStart()
.
User overridable callback: By default it calls preStart()
.
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.
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.
User overridable callback: By default it disposes of all children and then calls postStop()
.
User overridable callback: By default it disposes of all children and then calls postStop()
.
the Throwable that caused the restart to happen
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.
User overridable callback.
User overridable callback.
Is called when an Actor is started. Actors are automatically started asynchronously when created. Empty default implementation.
This defines the initial actor behavior, it must return a partial function with the actor logic.
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
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!
Set state timeout explicitly.
Set state timeout explicitly. This method can safely be used from within a state handler.
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.
identifier to be used with cancelTimer()
message to be delivered
delay of first message delivery and between subsequent messages
send once if false, scheduleAtFixedRate if true
current state descriptor
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.
initial state designator
initial state data
state timeout for the initial state, overriding the default timeout for that state
Return current state data (i.e.
Return current state data (i.e. object of type D)
Return current state name (i.e.
Return current state name (i.e. object of type S)
Produce "empty" transition descriptor.
Produce "empty" transition descriptor. Return this from a state function when no state change is to be effected.
descriptor for staying in current state
Produce change descriptor to stop this FSM actor including specified reason.
Produce change descriptor to stop this FSM actor including specified reason.
Produce change descriptor to stop this FSM actor including specified reason.
Produce change descriptor to stop this FSM actor including specified reason.
Produce change descriptor to stop this FSM actor with reason "Normal".
Produce change descriptor to stop this FSM actor with reason "Normal".
User overridable definition the strategy to use for supervising child actors.
User overridable definition the strategy to use for supervising child actors.
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.
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
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.
designator for the state
default state timeout for this state
partial function describing response to input
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
(clusterSingletonManager: ArrowAssoc[ClusterSingletonManager]).->(y)
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 suppliedsingletonProps
.The singleton actor is always running on the oldest member, which can be 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
actorSelection
using the names you have specified when creating the ClusterSingletonManager. You can subscribe to akka.cluster.ClusterEvent.MemberEvent and sort the members by age (akka.cluster.ClusterEvent.Member#isOlderThan) to keep track of oldest member. Alternatively the singleton actor may broadcast its existence when it is started.Use factory method to create the akka.actor.Props for the actor.
Arguments
singletonProps akka.actor.Props of the singleton actor instance.
singletonName The actor name of the child singleton actor.
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 fineterminationMessage
if you only need to stop the actor.role Singleton among the nodes tagged with specified role. If the role is not specified it's a singleton among all nodes in the cluster.
maxHandOverRetries When a node is becoming oldest it sends hand-over request to previous oldest. This is retried with the
retryInterval
until the previous oldest confirms that the hand over has started, or thismaxHandOverRetries
limit has been reached. If the retry limit is reached it takes the decision to be the new oldest if previous oldest is unknown (typically removed), otherwise it initiates a new round by throwing akka.contrib.pattern.ClusterSingletonManagerIsStuck and expecting restart with fresh state. For a cluster with many members you might need to increase this retry limit because it takes longer time to propagate changes across all nodes.maxTakeOverRetries When a oldest node is not oldest any more it sends take over request to the new oldest to initiate the normal hand-over process. This is especially useful when new node joins and becomes oldest immediately, without knowing who was previous oldest. This is retried with the
retryInterval
until this retry limit has been reached. If the retry limit is reached it initiates a new round by throwing akka.contrib.pattern.ClusterSingletonManagerIsStuck and expecting restart with fresh state. This will also cause the singleton actor to be stopped.maxTakeOverRetries
must be less thanmaxHandOverRetries
to ensure that new oldest doesn't start singleton actor before previous is stopped for certain corner cases.