rx.observables

Class AsyncOnSubscribe<S,T>

java.lang.Object

rx.observables.AsyncOnSubscribe<S,T>

Type Parameters:

S - the type of the user-define state used in generateState(S) , next(S, Long, Subscriber), and onUnsubscribe(S).

T - the type of Subscribers that will be compatible with this.

All Implemented Interfaces:

Action, Action1<Subscriber<? super T>>, Function, Observable.OnSubscribe<T>

@Experimental
public abstract class AsyncOnSubscribe<S,T>
extends java.lang.Object
implements Observable.OnSubscribe<T>

A utility class to create OnSubscribe<T> functions that respond correctly to back pressure requests from subscribers. This is an improvement over Observable.create(OnSubscribe) which does not provide any means of managing back pressure requests out-of-the-box. This variant of an OnSubscribe function allows for the asynchronous processing of requests.

Constructor Summary

Constructors

Constructor and Description
AsyncOnSubscribe()

Method Summary

Methods

Modifier and Type	Method and Description
void	call(Subscriber<? super T> actualSubscriber)
static <S,T> Observable.OnSubscribe<T>	createSingleState(Func0<? extends S> generator, Action3<? super S,java.lang.Long,? super Observer<Observable<? extends T>>> next) Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers.
static <S,T> Observable.OnSubscribe<T>	createSingleState(Func0<? extends S> generator, Action3<? super S,java.lang.Long,? super Observer<Observable<? extends T>>> next, Action1<? super S> onUnsubscribe) Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers.
static <S,T> Observable.OnSubscribe<T>	createStateful(Func0<? extends S> generator, Func3<? super S,java.lang.Long,? super Observer<Observable<? extends T>>,? extends S> next) Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers.
static <S,T> Observable.OnSubscribe<T>	createStateful(Func0<? extends S> generator, Func3<? super S,java.lang.Long,? super Observer<Observable<? extends T>>,? extends S> next, Action1<? super S> onUnsubscribe) Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers.
static <T> Observable.OnSubscribe<T>	createStateless(Action2<java.lang.Long,? super Observer<Observable<? extends T>>> next) Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers.
static <T> Observable.OnSubscribe<T>	createStateless(Action2<java.lang.Long,? super Observer<Observable<? extends T>>> next, Action0 onUnsubscribe) Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers.
protected abstract S	generateState() Executed once when subscribed to by a subscriber (via OnSubscribe#call(Subscriber)) to produce a state value.
protected abstract S	next(S state, long requested, Observer<Observable<? extends T>> observer) Called to produce data to the downstream subscribers.
protected void	onUnsubscribe(S state) Clean up behavior that is executed after the downstream subscriber's subscription is unsubscribed.

Methods inherited from class java.lang.Object

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

Constructor Detail

AsyncOnSubscribe

public AsyncOnSubscribe()

Method Detail

generateState

protected abstract S generateState()

Executed once when subscribed to by a subscriber (via OnSubscribe#call(Subscriber)) to produce a state value. This value is passed into next(S state, Observer observer) on the first iteration. Subsequent iterations of next will receive the state returned by the previous invocation of next.

Returns:

the initial state value

next

protected abstract S next(S state,
     long requested,
     Observer<Observable<? extends T>> observer)

Called to produce data to the downstream subscribers. To emit data to a downstream subscriber call observer.onNext(t). To signal an error condition call observer.onError(throwable) or throw an Exception. To signal the end of a data stream call observer.onCompleted(). Implementations of this method must follow the following rules.

• Must not call observer.onNext(t) more than 1 time per invocation.
• Must not call observer.onNext(t) concurrently.

The value returned from an invocation of this method will be passed in as the state argument of the next invocation of this method.

Parameters:

state - the state value (from generateState() on the first invocation or the previous invocation of this method.

requested - the amount of data requested. An observable emitted to the observer should not exceed this amount.

observer - the observer of data emitted by

Returns:

the next iteration's state value

onUnsubscribe

protected void onUnsubscribe(S state)

Clean up behavior that is executed after the downstream subscriber's subscription is unsubscribed. This method will be invoked exactly once.

Parameters:

state - the last state value returned from next(S, Long, Observer) or generateState() at the time when a terminal event is emitted from next(Object, long, Observer) or unsubscribing.

createSingleState

@Experimental
public static <S,T> Observable.OnSubscribe<T> createSingleState(Func0<? extends S> generator,
                                                             Action3<? super S,java.lang.Long,? super Observer<Observable<? extends T>>> next)

Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers.

Parameters:

generator - generates the initial state value (see generateState())

next - produces data to the downstream subscriber (see next(S, long, Observer))

Returns:

an OnSubscribe that emits data in a protocol compatible with back-pressure.

createSingleState

@Experimental
public static <S,T> Observable.OnSubscribe<T> createSingleState(Func0<? extends S> generator,
                                                             Action3<? super S,java.lang.Long,? super Observer<Observable<? extends T>>> next,
                                                             Action1<? super S> onUnsubscribe)

Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers. This overload creates a AsyncOnSubscribe without an explicit clean up step.

Parameters:

generator - generates the initial state value (see generateState())

next - produces data to the downstream subscriber (see next(S, long, Observer))

onUnsubscribe - clean up behavior (see onUnsubscribe(S))

Returns:

an OnSubscribe that emits data downstream in a protocol compatible with back-pressure.

createStateful

@Experimental
public static <S,T> Observable.OnSubscribe<T> createStateful(Func0<? extends S> generator,
                                                          Func3<? super S,java.lang.Long,? super Observer<Observable<? extends T>>,? extends S> next,
                                                          Action1<? super S> onUnsubscribe)

Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers.

Parameters:

generator - generates the initial state value (see generateState())

next - produces data to the downstream subscriber (see next(S, long, Observer))

onUnsubscribe - clean up behavior (see onUnsubscribe(S))

Returns:

an OnSubscribe that emits data downstream in a protocol compatible with back-pressure.

createStateful

@Experimental
public static <S,T> Observable.OnSubscribe<T> createStateful(Func0<? extends S> generator,
                                                          Func3<? super S,java.lang.Long,? super Observer<Observable<? extends T>>,? extends S> next)

Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers.

Parameters:

generator - generates the initial state value (see generateState())

next - produces data to the downstream subscriber (see next(S, long, Observer))

Returns:

an OnSubscribe that emits data downstream in a protocol compatible with back-pressure.

createStateless

@Experimental
public static <T> Observable.OnSubscribe<T> createStateless(Action2<java.lang.Long,? super Observer<Observable<? extends T>>> next)

Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers. This overload creates a "state-less" AsyncOnSubscribe which does not have an explicit state value. This should be used when the next function closes over it's state.

Parameters:

next - produces data to the downstream subscriber (see next(S, long, Observer))

Returns:

an OnSubscribe that emits data downstream in a protocol compatible with back-pressure.

createStateless

@Experimental
public static <T> Observable.OnSubscribe<T> createStateless(Action2<java.lang.Long,? super Observer<Observable<? extends T>>> next,
                                                         Action0 onUnsubscribe)

Generates a synchronous AsyncOnSubscribe that calls the provided next function to generate data to downstream subscribers. This overload creates a "state-less" AsyncOnSubscribe which does not have an explicit state value. This should be used when the next function closes over it's state.

Parameters:

next - produces data to the downstream subscriber (see next(S, long, Observer))

onUnsubscribe - clean up behavior (see onUnsubscribe(S))

Returns:

an OnSubscribe that emits data downstream in a protocol compatible with back-pressure.

call

public final void call(Subscriber<? super T> actualSubscriber)

Specified by:

call in interface Action1<Subscriber<? super T>>