Class SingleSubscriberPublisher<T>

java.lang.Object

graphql.execution.reactive.SingleSubscriberPublisher<T>

Type Parameters:

T - the things to publish

All Implemented Interfaces:

org.reactivestreams.Publisher<T>

public class SingleSubscriberPublisher<T>
extends Object
implements org.reactivestreams.Publisher<T>

A Publisher of things that are buffered and handles a single subscriber at a time. Rule #1 of reactive streams is don't write your own implementation. However rule #1 of graphql-java is that we have no unnecessary dependencies and force users into a code corner. So we chose to have a very simple implementation (single subscriber) implementation that allows a stream of results to be streamed out. People can wrap this is a more complete implementation if they so choose. Inspired by Public Domain CC0 code at https://github.com/jroper/reactive-streams-servlet/tree/master/reactive-streams-servlet/src/main/java/org/reactivestreams/servlet

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	SingleSubscriberPublisher.OnSubscriptionCallback	This is called when a subscription is made to the publisher
private class	SingleSubscriberPublisher.SimpleSubscription

Field Summary

Fields

Modifier and Type	Field	Description
private final Deque<T>	dataQ
private long	demand
private final NonBlockingMutexExecutor	mutex
private boolean	noMoreData
private Throwable	pendingThrowable
private boolean	running
private org.reactivestreams.Subscriber<? super T>	subscriber
private final SingleSubscriberPublisher.OnSubscriptionCallback	subscriptionCallback

Constructor Summary

Constructors

Constructor	Description
SingleSubscriberPublisher()	Constructs a publisher with no callback when subscribed
SingleSubscriberPublisher(SingleSubscriberPublisher.OnSubscriptionCallback subscriptionCallback)	The producing code can provide a callback to know when the subscriber attaches

Method Summary

Modifier and Type	Method	Description
private void	handleError(Throwable t)
private void	handleOnComplete()
private void	maybeReadInMutex()
void	noMoreData()	Called by the producing code to say there is no more data to offer and the stream is complete
void	offer(T data)	Called from the producing code to offer data up ready for a subscriber to read it
void	offerError(Throwable t)
void	subscribe(org.reactivestreams.Subscriber<? super T> subscriber)

Methods inherited from class Object

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

Field Details

dataQ

private final Deque<T> dataQ

mutex

private final NonBlockingMutexExecutor mutex

subscriptionCallback

private final SingleSubscriberPublisher.OnSubscriptionCallback subscriptionCallback

subscriber

private org.reactivestreams.Subscriber<? super T> subscriber

pendingThrowable

private Throwable pendingThrowable

running

private boolean running

noMoreData

private boolean noMoreData

demand

private long demand

Constructor Details

SingleSubscriberPublisher

public SingleSubscriberPublisher()

Constructs a publisher with no callback when subscribed

SingleSubscriberPublisher

public SingleSubscriberPublisher(SingleSubscriberPublisher.OnSubscriptionCallback subscriptionCallback)

The producing code can provide a callback to know when the subscriber attaches

Parameters:

subscriptionCallback - the callback when some ones

Method Details

offer

public void offer(T data)

Called from the producing code to offer data up ready for a subscriber to read it

Parameters:

data - the data to offer

noMoreData

public void noMoreData()

Called by the producing code to say there is no more data to offer and the stream is complete

offerError

public void offerError(Throwable t)

handleError

private void handleError(Throwable t)

handleOnComplete

private void handleOnComplete()

subscribe

public void subscribe(org.reactivestreams.Subscriber<? super T> subscriber)

Specified by:

subscribe in interface org.reactivestreams.Publisher<T>

maybeReadInMutex

private void maybeReadInMutex()