Package rx.internal.operators

Class DeferredScalarSubscriber<T,R>

java.lang.Object

rx.Subscriber<T>

rx.internal.operators.DeferredScalarSubscriber<T,R>

Type Parameters:

T - the source value type

R - the result value type

All Implemented Interfaces:

Observer<T>, Subscription

Direct Known Subclasses:

OnSubscribeCollect.CollectSubscriber, OnSubscribeReduceSeed.ReduceSeedSubscriber, OnSubscribeTakeLastOne.TakeLastOneSubscriber

public abstract class DeferredScalarSubscriber<T,R>
extends Subscriber<T>

Base class for Subscribers that consume the entire upstream and signal zero or one element (or an error) in a backpressure honoring fashion.

Store any temporary value in value and indicate there is a value available when completing by setting hasValue. subscribeTo(Observable) to properly setup the link between this and the downstream subscriber.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	DeferredScalarSubscriber.InnerProducer	Redirects the downstream request amount bach to the DeferredScalarSubscriber.

Field Summary

Fields

Modifier and Type	Field	Description
protected Subscriber<? super R>	actual	The downstream subscriber.
(package private) static int	HAS_REQUEST_HAS_VALUE	Value will be emitted.
(package private) static int	HAS_REQUEST_NO_VALUE	Request came first.
protected boolean	hasValue	Indicates there is a value available in value.
(package private) static int	NO_REQUEST_HAS_VALUE	Value came first.
(package private) static int	NO_REQUEST_NO_VALUE	Initial state.
(package private) java.util.concurrent.atomic.AtomicInteger	state	The state, see the constants below.
protected R	value	The holder of the single value.

Constructor Summary

Constructors

Constructor	Description
DeferredScalarSubscriber(Subscriber<? super R> actual)

Method Summary

Modifier and Type	Method	Description
protected void	complete()	Signals onCompleted() to the downstream subscriber.
protected void	complete(R value)	Atomically switches to the terminal state and emits the value if there is a request for it or stores it for retrieval by downstreamRequest(long).
(package private) void	downstreamRequest(long n)
void	onCompleted()	Notifies the Observer that the Observable has finished sending push-based notifications.
void	onError(java.lang.Throwable ex)	Notifies the Observer that the Observable has experienced an error condition.
void	setProducer(Producer p)	If other subscriber is set (by calling constructor Subscriber(Subscriber) or Subscriber(Subscriber, boolean)) then this method calls setProducer on the other subscriber.
(package private) void	setupDownstream()
void	subscribeTo(Observable<? extends T> source)	Links up with the downstream Subscriber (cancellation, backpressure) and subscribes to the source Observable.

Methods inherited from class rx.Subscriber

add, isUnsubscribed, onStart, request, unsubscribe

Methods inherited from class java.lang.Object

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

Methods inherited from interface rx.Observer

onNext

Field Detail

actual

protected final Subscriber<? super R> actual

The downstream subscriber.

hasValue

protected boolean hasValue

Indicates there is a value available in value.

value

protected R value

The holder of the single value.

state

final java.util.concurrent.atomic.AtomicInteger state

The state, see the constants below.

NO_REQUEST_NO_VALUE

static final int NO_REQUEST_NO_VALUE

Initial state.

See Also:

Constant Field Values

HAS_REQUEST_NO_VALUE

static final int HAS_REQUEST_NO_VALUE

Request came first.

See Also:

Constant Field Values

NO_REQUEST_HAS_VALUE

static final int NO_REQUEST_HAS_VALUE

Value came first.

See Also:

Constant Field Values

HAS_REQUEST_HAS_VALUE

static final int HAS_REQUEST_HAS_VALUE

Value will be emitted.

See Also:

Constant Field Values

Constructor Detail

DeferredScalarSubscriber

public DeferredScalarSubscriber(Subscriber<? super R> actual)

Method Detail

onError

public void onError(java.lang.Throwable ex)

Description copied from interface: Observer

Notifies the Observer that the Observable has experienced an error condition.

If the Observable calls this method, it will not thereafter call Observer.onNext(T) or Observer.onCompleted().

Parameters:

ex - the exception encountered by the Observable

onCompleted

public void onCompleted()

Description copied from interface: Observer

Notifies the Observer that the Observable has finished sending push-based notifications.

The Observable will not call this method if it calls Observer.onError(java.lang.Throwable).

complete

protected final void complete()

Signals onCompleted() to the downstream subscriber.

complete

protected final void complete(R value)

Atomically switches to the terminal state and emits the value if there is a request for it or stores it for retrieval by downstreamRequest(long).

Parameters:

value - the value to complete with

downstreamRequest

final void downstreamRequest(long n)

setProducer

public final void setProducer(Producer p)

Description copied from class: Subscriber

If other subscriber is set (by calling constructor Subscriber(Subscriber) or Subscriber(Subscriber, boolean)) then this method calls setProducer on the other subscriber. If the other subscriber is not set and no requests have been made to this subscriber then p.request(Long.MAX_VALUE) is called. If the other subscriber is not set and some requests have been made to this subscriber then p.request(n) is called where n is the accumulated requests to this subscriber.

Overrides:

setProducer in class Subscriber<T>

Parameters:

p - producer to be used by this subscriber or the other subscriber (or recursively its other subscriber) to make requests from

subscribeTo

public final void subscribeTo(Observable<? extends T> source)

Links up with the downstream Subscriber (cancellation, backpressure) and subscribes to the source Observable.

Parameters:

source - the source Observable

setupDownstream

final void setupDownstream()