rx.observers

Class SafeSubscriber<T>

java.lang.Object

rx.Subscriber<T>

rx.observers.SafeSubscriber<T>

Type Parameters:

T - the type of item expected by the Subscriber

All Implemented Interfaces:

Observer<T>, Subscription

public class SafeSubscriber<T>
extends Subscriber<T>

SafeSubscriber is a wrapper around Subscriber that ensures that the Subscriber complies with the Observable contract.

The following is taken from the Rx Design Guidelines document:

Messages sent to instances of the IObserver interface follow the following grammar:

OnNext* (OnCompleted | OnError)?

This grammar allows observable sequences to send any amount (0 or more) of OnNext messages to the subscriber, optionally followed by a single success (OnCompleted) or failure (OnError) message.

The single message indicating that an observable sequence has finished ensures that consumers of the observable sequence can deterministically establish that it is safe to perform cleanup operations.

A single failure further ensures that abort semantics can be maintained for operators that work on multiple observable sequences (see paragraph 6.6).

This wrapper does the following:

• Allows only single execution of either onError or onCompleted.
• Ensures that once an onCompleted or onError is performed, no further calls can be executed
• If unsubscribe is called, the upstream Observable is notified and the event delivery will be stopped in a best effort manner (i.e., further onXXX calls may still slip through).
• When onError or onCompleted occur, unsubscribes from the Observable (if executing asynchronously).

SafeSubscriber will not synchronize onNext execution. Use SerializedSubscriber to do that.

Constructor Summary

Constructors

Constructor and Description
SafeSubscriber(Subscriber<? super T> actual)

Method Summary

Modifier and Type	Method and Description
protected void	_onError(Throwable e) The logic for onError without the isFinished check so it can be called from within onCompleted.
Subscriber<? super T>	getActual() Returns the Subscriber underlying this SafeSubscriber.
void	onCompleted() Notifies the Subscriber that the Observable has finished sending push-based notifications.
void	onError(Throwable e) Notifies the Subscriber that the Observable has experienced an error condition.
void	onNext(T args) Provides the Subscriber with a new item to observe.

Methods inherited from class rx.Subscriber

add, isUnsubscribed, onStart, request, setProducer, unsubscribe

Methods inherited from class java.lang.Object

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

Constructor Detail

SafeSubscriber

public SafeSubscriber(Subscriber<? super T> actual)

Method Detail

onCompleted

public void onCompleted()

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

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

onError

public void onError(Throwable e)

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

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

Parameters:

e - the exception encountered by the Observable

onNext

public void onNext(T args)

Provides the Subscriber with a new item to observe.

The Observable may call this method 0 or more times.

The Observable will not call this method again after it calls either onCompleted() or onError(java.lang.Throwable).

Parameters:

args - the item emitted by the Observable

_onError

protected void _onError(Throwable e)

The logic for onError without the isFinished check so it can be called from within onCompleted.

See Also:

the report of this bug

getActual

public Subscriber<? super T> getActual()

Returns the Subscriber underlying this SafeSubscriber.

Returns:

the Subscriber that was used to create this SafeSubscriber