abstract class PushStage[In, Out] extends PushPullStage[In, Out]
PushStage
is a PushPullStage that always perform transitive pull by calling ctx.pull
from onPull
.
- Annotations
- @deprecated
- Deprecated
(Since version 2.4.2) Please use GraphStage instead.
- Source
- Stage.scala
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Instance Constructors
- new PushStage()
Abstract Value Members
-
abstract
def
onPush(elem: In, ctx: Context[Out]): SyncDirective
onPush
is called when an element from upstream is available and there is demand from downstream, i.e.onPush
is called when an element from upstream is available and there is demand from downstream, i.e. inonPush
you are allowed to call akka.stream.stage.Context#push to emit one element downstream, or you can absorb the element by calling akka.stream.stage.Context#pull. Note that you can only emit zero or one element downstream fromonPull
.To emit more than one element you have to push the remaining elements from #onPull, one-by-one.
onPush
is not called again untilonPull
has requested more elements with akka.stream.stage.Context#pull.- Definition Classes
- AbstractStage
Concrete Value Members
-
final
def
!=(arg0: Any): Boolean
- Definition Classes
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-
final
def
##(): Int
- Definition Classes
- AnyRef → Any
- def +(other: String): String
- def ->[B](y: B): (PushStage[In, Out], B)
-
final
def
==(arg0: Any): Boolean
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final
def
asInstanceOf[T0]: T0
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def
clone(): AnyRef
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- protected[java.lang]
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- @throws( ... )
-
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
- def ensuring(cond: (PushStage[In, Out]) ⇒ Boolean, msg: ⇒ Any): PushStage[In, Out]
- def ensuring(cond: (PushStage[In, Out]) ⇒ Boolean): PushStage[In, Out]
- def ensuring(cond: Boolean, msg: ⇒ Any): PushStage[In, Out]
- def ensuring(cond: Boolean): PushStage[In, Out]
-
final
def
eq(arg0: AnyRef): Boolean
- Definition Classes
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def
equals(arg0: Any): Boolean
- Definition Classes
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-
def
finalize(): Unit
- Attributes
- protected[java.lang]
- Definition Classes
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- Annotations
- @throws( classOf[java.lang.Throwable] )
- def formatted(fmtstr: String): String
-
final
def
getClass(): Class[_]
- Definition Classes
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-
def
hashCode(): Int
- Definition Classes
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final
def
isInstanceOf[T0]: Boolean
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final
def
ne(arg0: AnyRef): Boolean
- Definition Classes
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final
def
notify(): Unit
- Definition Classes
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final
def
notifyAll(): Unit
- Definition Classes
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-
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
Always pulls from upstream.
Always pulls from upstream.
- Definition Classes
- PushStage → 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
- 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
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def
toString(): String
- Definition Classes
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final
def
wait(): Unit
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- @throws( ... )
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final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
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- @throws( ... )
-
final
def
wait(arg0: Long): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
- def →[B](y: B): (PushStage[In, Out], B)