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.
- Annotations
- @deprecated
- Deprecated
(Since version 2.0-M2) StatefulStage is deprecated, please use GraphStage instead.
- Source
- Stage.scala
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- StatefulStage
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- AbstractStage
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Instance Constructors
- new StatefulStage()
Type Members
-
abstract
class
State
extends StageState[In, Out]
Scala API
Abstract Value Members
-
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
-
final
def
!=(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
final
def
##(): Int
- Definition Classes
- AnyRef → Any
-
def
+(other: String): String
- Implicit
- This member is added by an implicit conversion from StatefulStage[In, Out] to any2stringadd[StatefulStage[In, Out]] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
-
def
->[B](y: B): (StatefulStage[In, Out], B)
- Implicit
- This member is added by an implicit conversion from StatefulStage[In, Out] to ArrowAssoc[StatefulStage[In, Out]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
-
final
def
==(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
final
def
asInstanceOf[T0]: T0
- Definition Classes
- Any
-
final
def
become(state: StageState[In, Out]): Unit
Change the behavior to another StageState.
-
def
clone(): AnyRef
- Attributes
- protected[java.lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
current: StageState[In, Out]
Current state.
-
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
-
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 downstream and after that change behavior.
-
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 downstream and after that change behavior.
-
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 downstream.
-
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 downstream.
-
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 downstream and after that finish (complete downstreams, cancel upstreams).
-
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 downstream and after that finish (complete downstreams, cancel upstreams).
-
def
ensuring(cond: (StatefulStage[In, Out]) ⇒ Boolean, msg: ⇒ Any): StatefulStage[In, Out]
- Implicit
- This member is added by an implicit conversion from StatefulStage[In, Out] to Ensuring[StatefulStage[In, Out]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: (StatefulStage[In, Out]) ⇒ Boolean): StatefulStage[In, Out]
- Implicit
- This member is added by an implicit conversion from StatefulStage[In, Out] to Ensuring[StatefulStage[In, Out]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean, msg: ⇒ Any): StatefulStage[In, Out]
- Implicit
- This member is added by an implicit conversion from StatefulStage[In, Out] to Ensuring[StatefulStage[In, Out]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean): StatefulStage[In, Out]
- Implicit
- This member is added by an implicit conversion from StatefulStage[In, Out] to Ensuring[StatefulStage[In, Out]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
final
def
eq(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
-
def
equals(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
def
finalize(): Unit
- Attributes
- protected[java.lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( classOf[java.lang.Throwable] )
-
def
formatted(fmtstr: String): String
- Implicit
- This member is added by an implicit conversion from StatefulStage[In, Out] to StringFormat[StatefulStage[In, Out]] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @inline()
-
final
def
getClass(): Class[_]
- Definition Classes
- AnyRef → Any
-
def
hashCode(): Int
- Definition Classes
- AnyRef → Any
-
final
def
isInstanceOf[T0]: Boolean
- Definition Classes
- Any
-
final
def
ne(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
-
final
def
notify(): Unit
- Definition Classes
- AnyRef
-
final
def
notifyAll(): Unit
- Definition Classes
- AnyRef
-
def
onDownstreamFinish(ctx: Context[Out]): TerminationDirective
onDownstreamFinish
is called when downstream has canceled.onDownstreamFinish
is called when downstream has canceled.By default the cancel signal is immediately propagated with akka.stream.stage.Context#finish.
- Definition Classes
- AbstractStage
-
final
def
onPull(ctx: Context[Out]): SyncDirective
Invokes current state.
Invokes current state.
- Definition Classes
- StatefulStage → AbstractStage
-
final
def
onPush(elem: In, ctx: Context[Out]): SyncDirective
Invokes current state.
Invokes current state.
- Definition Classes
- StatefulStage → AbstractStage
-
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
-
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
- StatefulStage → AbstractStage
-
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] )
-
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] )
-
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
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
final
def
terminationEmit(iter: Iterator[Out], ctx: Context[Out]): TerminationDirective
Java API: Can be used from #onUpstreamFinish or #onUpstreamFailure to push final elements downstream.
-
final
def
terminationEmit(iter: Iterator[Out], ctx: Context[Out]): TerminationDirective
Scala API: Can be used from #onUpstreamFinish to push final elements downstream before completing the stream successfully.
Scala API: Can be used from #onUpstreamFinish to push final elements downstream 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.
-
def
toString(): String
- Definition Classes
- AnyRef → Any
-
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
def
→[B](y: B): (StatefulStage[In, Out], B)
- Implicit
- This member is added by an implicit conversion from StatefulStage[In, Out] to ArrowAssoc[StatefulStage[In, Out]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc