com.ibm.cos.v2.utils.async

Class BaseSubscriberAdapter<T,U>

java.lang.Object

com.ibm.cos.v2.utils.async.DelegatingSubscriber<T,U>

com.ibm.cos.v2.utils.async.BaseSubscriberAdapter<T,U>

Type Parameters:

T - the type that the delegate subscriber demands.

U - the type sent by the publisher this subscriber is subscribed to.

All Implemented Interfaces:

org.reactivestreams.Subscriber<T>

Direct Known Subclasses:

DelegatingBufferingSubscriber, FlatteningSubscriber

public abstract class BaseSubscriberAdapter<T,U>
extends DelegatingSubscriber<T,U>

Base of subscribers that can adapt one type to another. This subscriber will receive onNext signal with the U type, but will need to fulfill the downstream demand of the delegate subscriber with instance of the T type.

Field Summary

Fields

Modifier and Type	Field and Description
protected AtomicLong	downstreamDemand The amount of unfulfilled demand the downstream subscriber has opened against us.
protected AtomicBoolean	handlingStateUpdate A flag that is used to ensure that only one thread is handling updates to the state of this subscriber at a time.
protected boolean	onCompleteCalledByUpstream Whether the upstream subscriber has called onComplete on us.
protected AtomicReference<Throwable>	onErrorFromUpstream Whether the upstream subscriber has called onError on us.
protected boolean	terminalCallMadeDownstream Whether we have called onComplete or onNext on the downstream subscriber.
protected AtomicLong	upstreamDemand The amount of unfulfilled demand open against the upstream subscriber.
protected org.reactivestreams.Subscription	upstreamSubscription The subscription to the upstream subscriber.

Fields inherited from class com.ibm.cos.v2.utils.async.DelegatingSubscriber

subscriber

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BaseSubscriberAdapter(org.reactivestreams.Subscriber<? super U> subscriber)

Method Summary

Modifier and Type	Method and Description
protected abstract void	fulfillDownstreamDemand() This method is called when demand from the downstream subscriber needs to be fulfilled.
protected void	handleStateUpdate() This is invoked after each downstream request or upstream onNext, onError or onComplete.
void	onComplete()
void	onError(Throwable throwable)
void	onNext(T item)
void	onSubscribe(org.reactivestreams.Subscription subscription)

Methods inherited from class java.lang.Object

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

Field Detail

upstreamDemand

protected final AtomicLong upstreamDemand

The amount of unfulfilled demand open against the upstream subscriber.

downstreamDemand

protected final AtomicLong downstreamDemand

The amount of unfulfilled demand the downstream subscriber has opened against us.

handlingStateUpdate

protected final AtomicBoolean handlingStateUpdate

A flag that is used to ensure that only one thread is handling updates to the state of this subscriber at a time. This allows us to ensure that the downstream onNext, onComplete and onError are only ever invoked serially.

onErrorFromUpstream

protected final AtomicReference<Throwable> onErrorFromUpstream

Whether the upstream subscriber has called onError on us. If this is null, we haven't gotten an onError. If it's non-null this will be the exception that the upstream passed to our onError. After we get an onError, we'll call onError on the downstream subscriber as soon as possible.

terminalCallMadeDownstream

protected volatile boolean terminalCallMadeDownstream

Whether we have called onComplete or onNext on the downstream subscriber.

onCompleteCalledByUpstream

protected volatile boolean onCompleteCalledByUpstream

Whether the upstream subscriber has called onComplete on us. After this happens, we'll drain any outstanding items in the allItems queue and then call onComplete on the downstream subscriber.

upstreamSubscription

protected org.reactivestreams.Subscription upstreamSubscription

The subscription to the upstream subscriber.

Constructor Detail

BaseSubscriberAdapter

protected BaseSubscriberAdapter(org.reactivestreams.Subscriber<? super U> subscriber)

Method Detail

fulfillDownstreamDemand

protected abstract void fulfillDownstreamDemand()

This method is called when demand from the downstream subscriber needs to be fulfilled. Called in a loop until downstreamDemand is no longer needed. Implementations are responsible for decrementing the downstreamDemand accordingly as demand gets fulfilled.

onSubscribe

public void onSubscribe(org.reactivestreams.Subscription subscription)

Specified by:

onSubscribe in interface org.reactivestreams.Subscriber<T>

Overrides:

onSubscribe in class DelegatingSubscriber<T,U>

onNext

public void onNext(T item)

onError

public void onError(Throwable throwable)

Specified by:

onError in interface org.reactivestreams.Subscriber<T>

Overrides:

onError in class DelegatingSubscriber<T,U>

onComplete

public void onComplete()

Specified by:

onComplete in interface org.reactivestreams.Subscriber<T>

Overrides:

onComplete in class DelegatingSubscriber<T,U>

handleStateUpdate

protected void handleStateUpdate()

This is invoked after each downstream request or upstream onNext, onError or onComplete.