akka.actor

Class SupervisorStrategy

java.lang.Object

akka.actor.SupervisorStrategy

Direct Known Subclasses:

AllForOneStrategy, OneForOneStrategy, TestActor.DelegatingSupervisorStrategy

public abstract class SupervisorStrategy
extends java.lang.Object

An Akka SupervisorStrategy is the policy to apply for crashing children.

IMPORTANT:

You should not normally need to create new subclasses, instead use the existing OneForOneStrategy or AllForOneStrategy, but if you do, please read the docs of the methods below carefully, as incorrect implementations may lead to “blocked” actor systems (i.e. permanently suspended actors).

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	SupervisorStrategy.Directive
static class	SupervisorStrategy.Escalate$ Escalates the failure to the supervisor of the supervisor, by rethrowing the cause of the failure, i.e.
static class	SupervisorStrategy.Restart$ Discards the old Actor instance and replaces it with a new, then resumes message processing.
static class	SupervisorStrategy.Resume$ Resumes message processing for the failed Actor
static class	SupervisorStrategy.Stop$ Stops the Actor

Constructor Summary

Constructors

Constructor and Description
SupervisorStrategy()

Method Summary

Modifier and Type	Method and Description
abstract scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive>	decider() Returns the Decider that is associated with this SupervisorStrategy.
static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive>	defaultDecider() When supervisorStrategy is not specified for an actor this Decider is used by default in the supervisor strategy.
static SupervisorStrategy	defaultStrategy() When supervisorStrategy is not specified for an actor this is used by default.
static SupervisorStrategy.Escalate$	escalate() Java API: Returning this directive escalates the failure to the supervisor of the supervisor, by rethrowing the cause of the failure, i.e.
static scala.Function1<java.lang.Object,SupervisorStrategy.Escalate$>	escalateDefault()
abstract void	handleChildTerminated(ActorContext context, ActorRef child, scala.collection.Iterable<ActorRef> children) This method is called after the child has been removed from the set of children.
boolean	handleFailure(ActorContext context, ActorRef child, java.lang.Throwable cause, ChildRestartStats stats, scala.collection.Iterable<ChildRestartStats> children) This is the main entry point: in case of a child&rsquo;s failure, this method must try to handle the failure by resuming, restarting or stopping the child (and returning true), or it returns false to escalate the failure, which will lead to this actor re-throwing the exception which caused the failure.
void	logFailure(ActorContext context, ActorRef child, java.lang.Throwable cause, SupervisorStrategy.Directive decision) Default logging of actor failures when loggingEnabled() is true.
protected boolean	loggingEnabled() Logging of actor failures is done when this is true.
static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive>	makeDecider(Function<java.lang.Throwable,SupervisorStrategy.Directive> func) Converts a Java Decider into a Scala Decider
static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive>	makeDecider(java.lang.Iterable<java.lang.Class<? extends java.lang.Throwable>> trapExit) Decider builder which just checks whether one of the given Throwables matches the cause and restarts, otherwise escalates.
static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive>	makeDecider(scala.collection.Iterable<scala.Tuple2<java.lang.Class<? extends java.lang.Throwable>,SupervisorStrategy.Directive>> flat) Decider builder for Iterables of cause-directive pairs, e.g.
static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive>	makeDecider(scala.collection.immutable.Seq<java.lang.Class<? extends java.lang.Throwable>> trapExit) Decider builder which just checks whether one of the given Throwables matches the cause and restarts, otherwise escalates.
static scala.Option<java.lang.Object>	maxNrOfRetriesOption(int maxNrOfRetries)
abstract void	processFailure(ActorContext context, boolean restart, ActorRef child, java.lang.Throwable cause, ChildRestartStats stats, scala.collection.Iterable<ChildRestartStats> children) This method is called to act on the failure of a child: restart if the flag is true, stop otherwise.
static SupervisorStrategy.Restart$	restart() Java API: Returning this directive discards the old Actor instance and replaces it with a new, then resumes message processing.
void	restartChild(ActorRef child, java.lang.Throwable cause, boolean suspendFirst) Restart the given child, possibly suspending it first.
static SupervisorStrategy.Resume$	resume() Java API: Returning this directive resumes message processing for the failed Actor
void	resumeChild(ActorRef child, java.lang.Throwable cause) Resume the previously failed child: do never apply this to a child which is not the currently failing child.
static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive>	seqThrowable2Decider(scala.collection.immutable.Seq<java.lang.Class<? extends java.lang.Throwable>> trapExit) Implicit conversion from Seq of Throwables to a Decider.
static scala.collection.immutable.Seq<scala.Tuple2<java.lang.Class<? extends java.lang.Throwable>,SupervisorStrategy.Directive>>	sort(scala.collection.Iterable<scala.Tuple2<java.lang.Class<? extends java.lang.Throwable>,SupervisorStrategy.Directive>> in) Sort so that subtypes always precede their supertypes, but without obeying any order between unrelated subtypes (insert sort).
static SupervisorStrategy.Stop$	stop() Java API: Returning this directive stops the Actor
static SupervisorStrategy	stoppingStrategy() This strategy resembles Erlang in that failing children are always terminated (one-for-one).
static scala.Option<scala.concurrent.duration.Duration>	withinTimeRangeOption(scala.concurrent.duration.Duration withinTimeRange)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SupervisorStrategy

public SupervisorStrategy()

Method Detail

resume

public static SupervisorStrategy.Resume$ resume()

Java API: Returning this directive resumes message processing for the failed Actor

Returns:

(undocumented)

restart

public static SupervisorStrategy.Restart$ restart()

Java API: Returning this directive discards the old Actor instance and replaces it with a new, then resumes message processing.

Returns:

(undocumented)

stop

public static SupervisorStrategy.Stop$ stop()

Java API: Returning this directive stops the Actor

Returns:

(undocumented)

escalate

public static SupervisorStrategy.Escalate$ escalate()

Java API: Returning this directive escalates the failure to the supervisor of the supervisor, by rethrowing the cause of the failure, i.e. the supervisor fails with the same exception as the child.

Returns:

(undocumented)

defaultDecider

public static final scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive> defaultDecider()

When supervisorStrategy is not specified for an actor this Decider is used by default in the supervisor strategy. The child will be stopped when ActorInitializationException, ActorKilledException, or DeathPactException is thrown. It will be restarted for other Exception types. The error is escalated if it's a Throwable, i.e. Error.

Returns:

(undocumented)

defaultStrategy

public static final SupervisorStrategy defaultStrategy()

When supervisorStrategy is not specified for an actor this is used by default. OneForOneStrategy with decider defined in defaultDecider().

Returns:

(undocumented)

stoppingStrategy

public static final SupervisorStrategy stoppingStrategy()

This strategy resembles Erlang in that failing children are always terminated (one-for-one).

Returns:

(undocumented)

seqThrowable2Decider

public static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive> seqThrowable2Decider(scala.collection.immutable.Seq<java.lang.Class<? extends java.lang.Throwable>> trapExit)

Implicit conversion from Seq of Throwables to a Decider. This maps the given Throwables to restarts, otherwise escalates.

Parameters:

trapExit - (undocumented)

Returns:

(undocumented)

makeDecider

public static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive> makeDecider(scala.collection.immutable.Seq<java.lang.Class<? extends java.lang.Throwable>> trapExit)

Decider builder which just checks whether one of the given Throwables matches the cause and restarts, otherwise escalates.

Parameters:

trapExit - (undocumented)

Returns:

(undocumented)

makeDecider

public static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive> makeDecider(java.lang.Iterable<java.lang.Class<? extends java.lang.Throwable>> trapExit)

Decider builder which just checks whether one of the given Throwables matches the cause and restarts, otherwise escalates.

Parameters:

trapExit - (undocumented)

Returns:

(undocumented)

makeDecider

public static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive> makeDecider(scala.collection.Iterable<scala.Tuple2<java.lang.Class<? extends java.lang.Throwable>,SupervisorStrategy.Directive>> flat)

Decider builder for Iterables of cause-directive pairs, e.g. a map obtained from configuration; will sort the pairs so that the most specific type is checked before all its subtypes, allowing carving out subtrees of the Throwable hierarchy.

Parameters:

flat - (undocumented)

Returns:

(undocumented)

makeDecider

public static scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive> makeDecider(Function<java.lang.Throwable,SupervisorStrategy.Directive> func)

Converts a Java Decider into a Scala Decider

Parameters:

func - (undocumented)

Returns:

(undocumented)

sort

public static scala.collection.immutable.Seq<scala.Tuple2<java.lang.Class<? extends java.lang.Throwable>,SupervisorStrategy.Directive>> sort(scala.collection.Iterable<scala.Tuple2<java.lang.Class<? extends java.lang.Throwable>,SupervisorStrategy.Directive>> in)

Sort so that subtypes always precede their supertypes, but without obeying any order between unrelated subtypes (insert sort).

INTERNAL API

Parameters:

in - (undocumented)

Returns:

(undocumented)

withinTimeRangeOption

public static scala.Option<scala.concurrent.duration.Duration> withinTimeRangeOption(scala.concurrent.duration.Duration withinTimeRange)

maxNrOfRetriesOption

public static scala.Option<java.lang.Object> maxNrOfRetriesOption(int maxNrOfRetries)

escalateDefault

public static scala.Function1<java.lang.Object,SupervisorStrategy.Escalate$> escalateDefault()

decider

public abstract scala.PartialFunction<java.lang.Throwable,SupervisorStrategy.Directive> decider()

Returns the Decider that is associated with this SupervisorStrategy. The Decider is invoked by the default implementation of handleFailure to obtain the Directive to be applied.

Returns:

(undocumented)

handleChildTerminated

public abstract void handleChildTerminated(ActorContext context,
                                           ActorRef child,
                                           scala.collection.Iterable<ActorRef> children)

This method is called after the child has been removed from the set of children. It does not need to do anything special. Exceptions thrown from this method do NOT make the actor fail if this happens during termination.

Parameters:

context - (undocumented)

child - (undocumented)

children - (undocumented)

processFailure

public abstract void processFailure(ActorContext context,
                                    boolean restart,
                                    ActorRef child,
                                    java.lang.Throwable cause,
                                    ChildRestartStats stats,
                                    scala.collection.Iterable<ChildRestartStats> children)

This method is called to act on the failure of a child: restart if the flag is true, stop otherwise.

Parameters:

context - (undocumented)

restart - (undocumented)

child - (undocumented)

cause - (undocumented)

stats - (undocumented)

children - (undocumented)

handleFailure

public boolean handleFailure(ActorContext context,
                             ActorRef child,
                             java.lang.Throwable cause,
                             ChildRestartStats stats,
                             scala.collection.Iterable<ChildRestartStats> children)

This is the main entry point: in case of a child’s failure, this method must try to handle the failure by resuming, restarting or stopping the child (and returning true), or it returns false to escalate the failure, which will lead to this actor re-throwing the exception which caused the failure. The exception will not be wrapped.

This method calls logFailure(akka.actor.ActorContext, akka.actor.ActorRef, java.lang.Throwable, akka.actor.SupervisorStrategy.Directive), which will log the failure unless it is escalated. You can customize the logging by setting loggingEnabled() to false and do the logging inside the decider or override the logFailure method.

Parameters:

children - is a lazy collection (a view)

context - (undocumented)

cause - (undocumented)

stats - (undocumented)

Returns:

(undocumented)

loggingEnabled

protected boolean loggingEnabled()

Logging of actor failures is done when this is true.

Returns:

(undocumented)

logFailure

public void logFailure(ActorContext context,
                       ActorRef child,
                       java.lang.Throwable cause,
                       SupervisorStrategy.Directive decision)

Default logging of actor failures when loggingEnabled() is true. Escalate failures are not logged here, since they are supposed to be handled at a level higher up in the hierarchy. Resume failures are logged at Warning level. Stop and Restart failures are logged at Error level.

Parameters:

context - (undocumented)

child - (undocumented)

cause - (undocumented)

decision - (undocumented)

resumeChild

public final void resumeChild(ActorRef child,
                              java.lang.Throwable cause)

Resume the previously failed child: do never apply this to a child which is not the currently failing child. Suspend/resume needs to be done in matching pairs, otherwise actors will wake up too soon or never at all.

Parameters:

child - (undocumented)

cause - (undocumented)

restartChild

public final void restartChild(ActorRef child,
                               java.lang.Throwable cause,
                               boolean suspendFirst)

Restart the given child, possibly suspending it first.

IMPORTANT:

If the child is the currently failing one, it will already have been suspended, hence suspendFirst must be false. If the child is not the currently failing one, then it did not request this treatment and is therefore not prepared to be resumed without prior suspend.

Parameters:

child - (undocumented)

cause - (undocumented)

suspendFirst - (undocumented)