StatefulStage(TIn, TOut) Class

StatefulStageTIn, TOut Class

Note: This API is now obsolete.

StatefulStageTIn, TOut is a PushPullStageTIn, TOut that provides convenience to make some things easier. The behavior is defined in StageStateTIn, TOut instances. The initial behavior is specified by subclass implementing the Initial method. The behavior can be changed by using Become(StageStateTIn, TOut). Use Emit(IEnumeratorTOut, IContextTOut, StageStateTIn, TOut) or EmitAndFinish(IEnumeratorTOut, IContextTOut) to push more than one element from OnPush(TIn, IContextTOut) or OnPull(IContextTOut). Use TerminationEmit(IEnumeratorTOut, IContextTOut) to push final elements from OnUpstreamFinish(IContextTOut) or OnUpstreamFailure(Exception, IContext).

Inheritance Hierarchy

SystemObject
  Akka.Streams.StageAbstractStageTIn, TOut
    Akka.Streams.StageAbstractStageTIn, TOut, ISyncDirective, ISyncDirective, IContextTOut
      Akka.Streams.StagePushPullStageTIn, TOut
        Akka.Streams.StageStatefulStageTIn, TOut

Namespace: Akka.Streams.Stage
Assembly: Akka.Streams (in Akka.Streams.dll) Version: 1.2.3.42 (1.2.3.42)

Syntax

Copy

[ObsoleteAttribute("Please use GraphStage instead. [1.1.0]")]
public abstract class StatefulStage<TIn, TOut> : PushPullStage<TIn, TOut>

[<AbstractClassAttribute>]
[<ObsoleteAttribute("Please use GraphStage instead. [1.1.0]")>]
type StatefulStage<'TIn, 'TOut> =  
    class
        inherit PushPullStage<'TIn, 'TOut>
    end

Type Parameters

TIn: TBD
TOut: TBD

The StatefulStageTIn, TOut type exposes the following members.

Constructors

	Name	Description
	StatefulStageTIn, TOut	TBD

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Properties

	Name	Description
	Current	Current state.
	Initial	Concrete subclass must return the initial behavior from this method. Warning: This method must not be implemented as `val`.
	IsDetached	TBD (Inherited from AbstractStageTIn, TOut.)

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Methods

	Name	Description
	Become	Change the behavior to another StageStateTIn, TOut.
	Decide	If an exception is thrown from OnPush(TIn, IContext) this method is invoked to decide how to handle the exception. By default this method returns Stop. If an exception is thrown from OnPull(IContext) 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(IContext) when it is know how to recover from such exceptions. (Inherited from AbstractStageTIn, TOut.)
	Emit(IEnumeratorTOut, IContextTOut)	Can be used from OnPush(TIn, IContextTOut) or OnPull(IContextTOut) to push more than one element downstream.
	Emit(IEnumeratorTOut, IContextTOut, StageStateTIn, TOut)	Can be used from OnPush(TIn, IContextTOut) or OnPull(IContextTOut) to push more than one element downstream and after that change behavior.
	EmitAndFinish	Can be used from OnPush(TIn, IContextTOut) or OnPull(IContextTOut) to push more than one element downstream and after that finish (complete downstream, cancel upstreams).
	Equals	Determines whether the specified object is equal to the current object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
	GetHashCode	Serves as the default hash function. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	OnDownstreamFinish(TContext)	This method is called when downstream has cancelled. By default the cancel signal is immediately propagated with Finish. (Inherited from AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContext.)
	OnDownstreamFinish(IContext)	This method is called when downstream has cancelled. By default the cancel signal is immediately propagated with Finish. (Inherited from AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContext.)
	OnPull(IContext)	This method is called when there is demand from downstream, i.e. you are allowed to push one element downstreams with Push(Object), or request elements from upstreams with Pull (Inherited from AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContext.)
	OnPull(IContextTOut)	Invokes current state. (Overrides AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContextOnPull(TContext).)
	OnPush(TIn, TContext)	This method is called when an element from upstream is available and there is demand from downstream, i.e. in OnPush(TIn, TContext) you are allowed to call Push(Object) to emit one element downstreams, or you can absorb the element by calling Pull. Note that you can only emit zero or one element downstream from OnPull(TContext). To emit more than one element you have to push the remaining elements from OnPull(TContext), one-by-one. OnPush(TIn, TContext) is not called again until OnPull(TContext) has requested more elements with Pull. (Inherited from AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContext.)
	OnPush(TIn, IContextTOut)	Invokes current state. (Overrides AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContextOnPush(TIn, TContext).)
	OnUpstreamFailure(Exception, IContext)	OnUpstreamFailure(Exception, IContext) is called when upstream has signaled that the stream is completed with failure. It is not called if OnPull(TContext) or OnPush(TIn, TContext) 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(Exception, IContext) is called, i.e. failures are not backpressured and might be propagated as soon as possible. Here you cannot call Push(Object), because there might not be any demand from downstream. To emit additional elements before terminating you can use AbsorbTermination and push final elements from OnPull(TContext). The stage will then be in finishing state, which can be checked with IsFinishing. (Inherited from AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContext.)
	OnUpstreamFailure(Exception, TContext)	OnUpstreamFailure(Exception, IContext) is called when upstream has signaled that the stream is completed with failure. It is not called if OnPull(TContext) or OnPush(TIn, TContext) 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(Exception, IContext) is called, i.e. failures are not backpressured and might be propagated as soon as possible. Here you cannot call Push(Object), because there might not be any demand from downstream. To emit additional elements before terminating you can use AbsorbTermination and push final elements from OnPull(TContext). The stage will then be in finishing state, which can be checked with IsFinishing. (Inherited from AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContext.)
	OnUpstreamFinish(IContext)	This method is called when upstream has signaled that the stream is successfully completed. Here you cannot call Push(Object), because there might not be any demand from downstream. To emit additional elements before terminating you can use AbsorbTermination and push final elements from OnPull(TContext). The stage will then be in finishing state, which can be checked with IsFinishing. By default the finish signal is immediately propagated with 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". (Inherited from AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContext.)
	OnUpstreamFinish(IContextTOut)	TBD (Overrides AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContextOnUpstreamFinish(TContext).)
	PostStop	User overridable callback. Is called after the Stages final action is performed. Empty default implementation. (Inherited from AbstractStageTIn, TOut.)
	PreStart	User overridable callback. It is called before any other method defined on the IStageTIn, TOut. Empty default implementation. (Inherited from AbstractStageTIn, TOut.)
	Restart	Used to create a fresh instance of the stage after an error resulting in a 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. (Inherited from AbstractStageTIn, TOut.)
	TerminationEmit	Can be used from OnUpstreamFinish(IContextTOut) to push final elements downstream before completing the stream successfully. Note that if this is used from OnUpstreamFailure(Exception, IContext) the failure will be absorbed and the stream will be completed successfully.
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Fields

	Name	Description
	Context	TBD (Inherited from AbstractStageTIn, TOut, TPushDirective, TPullDirective, TContext.)

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Extension Methods

	Name	Description
	AsInstanceOfT	TBD (Defined by Extensions.)
	Match	Overloaded. Matches the specified target. (Defined by PatternMatch.)
	MatchT	Overloaded. Matches the specified target and return a result of target processing. (Defined by PatternMatch.)

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Reference

Akka.Streams.Stage Namespace