akka.stream.stage

StatefulStage

abstract class StatefulStage[In, Out] extends PushPullStage[In, Out]

StatefulStage is a PushPullStage that provides convenience to make some things easier.

The behavior is defined in StageState instances. The initial behavior is specified by subclass implementing the #initial method. The behavior can be changed by using #become.

Use #emit or #emitAndFinish to push more than one element from StageState#onPush or StageState#onPull.

Use #terminationEmit to push final elements from #onUpstreamFinish or #onUpstreamFailure.

Source
Stage.scala
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  1. StatefulStage
  2. PushPullStage
  3. AbstractStage
  4. Stage
  5. AnyRef
  6. Any
Implicitly
  1. by any2stringadd
  2. by any2stringfmt
  3. by any2ArrowAssoc
  4. by any2Ensuring
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Instance Constructors

  1. new StatefulStage()

Type Members

  1. abstract class State extends StageState[In, Out]

    Scala API

Abstract Value Members

  1. abstract def initial: StageState[In, Out]

    Concrete subclass must return the initial behavior from this method.

    Concrete subclass must return the initial behavior from this method.

    **Warning:** This method must not be implemented as val.

Concrete Value Members

  1. final def !=(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  2. final def !=(arg0: Any): Boolean

    Definition Classes
    Any
  3. final def ##(): Int

    Definition Classes
    AnyRef → Any
  4. def +(other: String): String

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to StringAdd performed by method any2stringadd in scala.Predef.
    Definition Classes
    StringAdd
  5. def ->[B](y: B): (StatefulStage[In, Out], B)

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to ArrowAssoc[StatefulStage[In, Out]] performed by method any2ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  6. final def ==(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  7. final def ==(arg0: Any): Boolean

    Definition Classes
    Any
  8. final def asInstanceOf[T0]: T0

    Definition Classes
    Any
  9. final def become(state: StageState[In, Out]): Unit

    Change the behavior to another StageState.

  10. def clone(): AnyRef

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  11. final def current: StageState[In, Out]

    Current state.

  12. def decide(t: Throwable): Supervision.Directive

    If an exception is thrown from #onPush this method is invoked to decide how to handle the exception.

    If an exception is thrown from #onPush this method is invoked to decide how to handle the exception. By default this method returns Supervision.Stop.

    If an exception is thrown from #onPull the stream will always be completed with failure, because it is not always possible to recover from that state. In concrete stages it is of course possible to use ordinary try-catch-recover inside onPull when it is know how to recover from such exceptions.

    Definition Classes
    AbstractStage
  13. final def emit(iter: Iterator[Out], ctx: Context[Out], nextState: StageState[In, Out]): SyncDirective

    Java API: Can be used from StageState#onPush or StageState#onPull to push more than one element downstreams and after that change behavior.

  14. final def emit(iter: Iterator[Out], ctx: Context[Out], nextState: StageState[In, Out]): SyncDirective

    Scala API: Can be used from StageState#onPush or StageState#onPull to push more than one element downstreams and after that change behavior.

  15. final def emit(iter: Iterator[Out], ctx: Context[Out]): SyncDirective

    Java API: Can be used from StageState#onPush or StageState#onPull to push more than one element downstreams.

  16. final def emit(iter: Iterator[Out], ctx: Context[Out]): SyncDirective

    Scala API: Can be used from StageState#onPush or StageState#onPull to push more than one element downstreams.

  17. final def emitAndFinish(iter: Iterator[Out], ctx: Context[Out]): SyncDirective

    Java API: Can be used from StageState#onPush or StageState#onPull to push more than one element downstreams and after that finish (complete downstreams, cancel upstreams).

  18. final def emitAndFinish(iter: Iterator[Out], ctx: Context[Out]): SyncDirective

    Scala API: Can be used from StageState#onPush or StageState#onPull to push more than one element downstreams and after that finish (complete downstreams, cancel upstreams).

  19. def ensuring(cond: (StatefulStage[In, Out]) ⇒ Boolean, msg: ⇒ Any): StatefulStage[In, Out]

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to Ensuring[StatefulStage[In, Out]] performed by method any2Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  20. def ensuring(cond: (StatefulStage[In, Out]) ⇒ Boolean): StatefulStage[In, Out]

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to Ensuring[StatefulStage[In, Out]] performed by method any2Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  21. def ensuring(cond: Boolean, msg: ⇒ Any): StatefulStage[In, Out]

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to Ensuring[StatefulStage[In, Out]] performed by method any2Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  22. def ensuring(cond: Boolean): StatefulStage[In, Out]

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to Ensuring[StatefulStage[In, Out]] performed by method any2Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  23. final def eq(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  24. def equals(arg0: Any): Boolean

    Definition Classes
    AnyRef → Any
  25. def finalize(): Unit

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  26. def formatted(fmtstr: String): String

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to StringFormat performed by method any2stringfmt in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  27. final def getClass(): Class[_]

    Definition Classes
    AnyRef → Any
  28. def hashCode(): Int

    Definition Classes
    AnyRef → Any
  29. final def isInstanceOf[T0]: Boolean

    Definition Classes
    Any
  30. final def ne(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  31. final def notify(): Unit

    Definition Classes
    AnyRef
  32. final def notifyAll(): Unit

    Definition Classes
    AnyRef
  33. def onDownstreamFinish(ctx: Context[Out]): TerminationDirective

    onDownstreamFinish is called when downstream has cancelled.

    onDownstreamFinish is called when downstream has cancelled.

    By default the cancel signal is immediately propagated with akka.stream.stage.Context#finish.

    Definition Classes
    AbstractStage
  34. final def onPull(ctx: Context[Out]): SyncDirective

    Invokes current state.

    Invokes current state.

    Definition Classes
    StatefulStageAbstractStage
  35. final def onPush(elem: In, ctx: Context[Out]): SyncDirective

    Invokes current state.

    Invokes current state.

    Definition Classes
    StatefulStageAbstractStage
  36. def onUpstreamFailure(cause: Throwable, ctx: Context[Out]): TerminationDirective

    onUpstreamFailure is called when upstream has signaled that the stream is completed with failure.

    onUpstreamFailure is called when upstream has signaled that the stream is completed with failure. It is not called if #onPull or #onPush of the stage itself throws an exception.

    Note that elements that were emitted by upstream before the failure happened might not have been received by this stage when onUpstreamFailure is called, i.e. failures are not backpressured and might be propagated as soon as possible.

    Here you cannot call akka.stream.stage.Context#push, because there might not be any demand from downstream. To emit additional elements before terminating you can use akka.stream.stage.Context#absorbTermination and push final elements from #onPull. The stage will then be in finishing state, which can be checked with akka.stream.stage.Context#isFinishing.

    Definition Classes
    AbstractStage
  37. def onUpstreamFinish(ctx: Context[Out]): TerminationDirective

    onUpstreamFinish is called when upstream has signaled that the stream is successfully completed.

    onUpstreamFinish is called when upstream has signaled that the stream is successfully completed. Here you cannot call akka.stream.stage.Context#push, because there might not be any demand from downstream. To emit additional elements before terminating you can use akka.stream.stage.Context#absorbTermination and push final elements from #onPull. The stage will then be in finishing state, which can be checked with akka.stream.stage.Context#isFinishing.

    By default the finish signal is immediately propagated with akka.stream.stage.Context#finish.

    *IMPORTANT NOTICE:* this signal is not back-pressured, it might arrive from upstream even though the last action by this stage was a “push”.

    Definition Classes
    StatefulStageAbstractStage
  38. def postStop(): Unit

    User overridable callback.

    User overridable callback.

    Is called after the Stages final action is performed. // TODO need better wording here Empty default implementation.

    Definition Classes
    AbstractStage
    Annotations
    @throws( classOf[Exception] )
  39. def preStart(ctx: LifecycleContext): Unit

    User overridable callback.

    User overridable callback.

    It is called before any other method defined on the Stage. Empty default implementation.

    Definition Classes
    AbstractStage
    Annotations
    @throws( classOf[Exception] )
  40. def restart(): Stage[In, Out]

    Used to create a fresh instance of the stage after an error resulting in a Supervision.Restart directive.

    Used to create a fresh instance of the stage after an error resulting in a Supervision.Restart directive. By default it will return the same instance untouched, so you must override it if there are any state that should be cleared before restarting, e.g. by returning a new instance.

    Definition Classes
    AbstractStage
  41. final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
    AnyRef
  42. final def terminationEmit(iter: Iterator[Out], ctx: Context[Out]): TerminationDirective

    Java API: Can be used from #onUpstreamFinish or #onUpstreamFailure to push final elements downstreams.

  43. final def terminationEmit(iter: Iterator[Out], ctx: Context[Out]): TerminationDirective

    Scala API: Can be used from #onUpstreamFinish to push final elements downstreams before completing the stream successfully.

    Scala API: Can be used from #onUpstreamFinish to push final elements downstreams before completing the stream successfully. Note that if this is used from #onUpstreamFailure the failure will be absorbed and the stream will be completed successfully.

  44. def toString(): String

    Definition Classes
    AnyRef → Any
  45. final def wait(): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  46. final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  47. final def wait(arg0: Long): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  48. def [B](y: B): (StatefulStage[In, Out], B)

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to ArrowAssoc[StatefulStage[In, Out]] performed by method any2ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc

Shadowed Implicit Value Members

  1. val self: Any

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to StringAdd performed by method any2stringadd in scala.Predef.
    Shadowing
    This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
    To access this member you can use a type ascription:
    (statefulStage: StringAdd).self
    Definition Classes
    StringAdd
  2. val self: Any

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to StringFormat performed by method any2stringfmt in scala.Predef.
    Shadowing
    This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
    To access this member you can use a type ascription:
    (statefulStage: StringFormat).self
    Definition Classes
    StringFormat

Deprecated Value Members

  1. def x: StatefulStage[In, Out]

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to ArrowAssoc[StatefulStage[In, Out]] performed by method any2ArrowAssoc in scala.Predef.
    Shadowing
    This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
    To access this member you can use a type ascription:
    (statefulStage: ArrowAssoc[StatefulStage[In, Out]]).x
    Definition Classes
    ArrowAssoc
    Annotations
    @deprecated
    Deprecated

    (Since version 2.10.0) Use leftOfArrow instead

  2. def x: StatefulStage[In, Out]

    Implicit information
    This member is added by an implicit conversion from StatefulStage[In, Out] to Ensuring[StatefulStage[In, Out]] performed by method any2Ensuring in scala.Predef.
    Shadowing
    This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
    To access this member you can use a type ascription:
    (statefulStage: Ensuring[StatefulStage[In, Out]]).x
    Definition Classes
    Ensuring
    Annotations
    @deprecated
    Deprecated

    (Since version 2.10.0) Use resultOfEnsuring instead

Inherited from PushPullStage[In, Out]

Inherited from Stage[In, Out]

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd from StatefulStage[In, Out] to StringAdd

Inherited by implicit conversion any2stringfmt from StatefulStage[In, Out] to StringFormat

Inherited by implicit conversion any2ArrowAssoc from StatefulStage[In, Out] to ArrowAssoc[StatefulStage[In, Out]]

Inherited by implicit conversion any2Ensuring from StatefulStage[In, Out] to Ensuring[StatefulStage[In, Out]]

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