org.springframework.http.server.reactive

Class AbstractListenerWriteProcessor<T>

java.lang.Object

org.springframework.http.server.reactive.AbstractListenerWriteProcessor<T>

Type Parameters:

T - the type of element signaled to the Subscriber

All Implemented Interfaces:

Processor<T,Void>, Publisher<Void>, Subscriber<T>

Direct Known Subclasses:

AbstractListenerWebSocketSession.WebSocketSendProcessor

public abstract class AbstractListenerWriteProcessor<T>
extends Object
implements Processor<T,Void>

Abstract base class for Processor implementations that bridge between event-listener write APIs and Reactive Streams.

Specifically a base class for writing to the HTTP response body with Servlet 3.1 non-blocking I/O and Undertow XNIO as well for writing WebSocket messages through the Java WebSocket API (JSR-356), Jetty, and Undertow.

Since:

5.0

Author:

Arjen Poutsma, Violeta Georgieva, Rossen Stoyanchev

Field Summary

Fields

Modifier and Type	Field and Description
protected static Log	rsWriteLogger Special logger for debugging Reactive Streams signals.

Constructor Summary

Constructors

Constructor and Description
AbstractListenerWriteProcessor()
AbstractListenerWriteProcessor(String logPrefix) Create an instance with the given log prefix.

Method Summary

Modifier and Type	Method and Description
void	cancel() Cancel the upstream "write" Publisher only, for example due to Servlet container error/completion notifications.
protected void	dataReceived(T data) Template method invoked after a data item to write is received via Subscriber.onNext(Object).
protected abstract void	discardData(T data) Invoked after any error (either from the upstream write Publisher, or from I/O operations to the underlying server) and cancellation to discard in-flight data that was in the process of being written when the error took place.
String	getLogPrefix() Get the configured log prefix.
protected abstract boolean	isDataEmpty(T data) Whether the given data item has any content to write.
protected abstract boolean	isWritePossible() Whether writing is possible.
void	onComplete() Completion signal from the upstream, write Publisher.
void	onError(Throwable ex) Error signal from the upstream, write Publisher.
void	onNext(T data)
void	onSubscribe(Subscription subscription)
void	onWritePossible() Invoked when writing is possible, either in the same thread after a check via isWritePossible(), or as a callback from the underlying container.
void	subscribe(Subscriber<? super Void> subscriber)
protected abstract boolean	write(T data) Write the given item.
protected void	writingComplete() Invoked after onComplete or onError notification.
protected void	writingFailed(Throwable ex) Invoked when an I/O error occurs during a write.
protected void	writingPaused() Deprecated. originally introduced for Undertow to stop write notifications when no data is available, but deprecated as of 5.0.6 since constant switching on every requested item causes a significant slowdown.

Methods inherited from class java.lang.Object

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

Field Detail

rsWriteLogger

protected static final Log rsWriteLogger

Special logger for debugging Reactive Streams signals.

See Also:

LogDelegateFactory.getHiddenLog(Class), AbstractListenerReadPublisher.rsReadLogger, AbstractListenerWriteFlushProcessor.rsWriteFlushLogger, WriteResultPublisher.rsWriteResultLogger

Constructor Detail

AbstractListenerWriteProcessor

public AbstractListenerWriteProcessor()

AbstractListenerWriteProcessor

public AbstractListenerWriteProcessor(String logPrefix)

Create an instance with the given log prefix.

Since:

5.1

Method Detail

getLogPrefix

public String getLogPrefix()

Get the configured log prefix.

Since:

5.1

onSubscribe

public final void onSubscribe(Subscription subscription)

Specified by:

onSubscribe in interface Subscriber<T>

onNext

public final void onNext(T data)

Specified by:

onNext in interface Subscriber<T>

onError

public final void onError(Throwable ex)

Error signal from the upstream, write Publisher. This is also used by subclasses to delegate error notifications from the container.

Specified by:

onError in interface Subscriber<T>

onComplete

public final void onComplete()

Completion signal from the upstream, write Publisher. This is also used by subclasses to delegate completion notifications from the container.

Specified by:

onComplete in interface Subscriber<T>

onWritePossible

public final void onWritePossible()

Invoked when writing is possible, either in the same thread after a check via isWritePossible(), or as a callback from the underlying container.

cancel

public void cancel()

Cancel the upstream "write" Publisher only, for example due to Servlet container error/completion notifications. This should usually be followed up with a call to either onError(Throwable) or onComplete() to notify the downstream chain, that is unless cancellation came from downstream.

subscribe

public final void subscribe(Subscriber<? super Void> subscriber)

Specified by:

subscribe in interface Publisher<Void>

isDataEmpty

protected abstract boolean isDataEmpty(T data)

Whether the given data item has any content to write. If false the item is not written.

dataReceived

protected void dataReceived(T data)

Template method invoked after a data item to write is received via Subscriber.onNext(Object). The default implementation saves the data item for writing once that is possible.

isWritePossible

protected abstract boolean isWritePossible()

Whether writing is possible.

write

protected abstract boolean write(T data)
                          throws IOException

Write the given item.

Note: Sub-classes are responsible for releasing any data buffer associated with the item, once fully written, if pooled buffers apply to the underlying container.

Parameters:

data - the item to write

Returns:

true if the current data item was written completely and a new item requested, or false if it was written partially and we'll need more write callbacks before it is fully written

Throws:

IOException

writingPaused

@Deprecated
protected void writingPaused()

Deprecated. originally introduced for Undertow to stop write notifications when no data is available, but deprecated as of 5.0.6 since constant switching on every requested item causes a significant slowdown.

Invoked after the current data has been written and before requesting the next item from the upstream, write Publisher.

The default implementation is a no-op.

writingComplete

protected void writingComplete()

Invoked after onComplete or onError notification.

The default implementation is a no-op.

writingFailed

protected void writingFailed(Throwable ex)

Invoked when an I/O error occurs during a write. Subclasses may choose to ignore this if they know the underlying API will provide an error notification in a container thread.

Defaults to no-op.

discardData

protected abstract void discardData(T data)

Invoked after any error (either from the upstream write Publisher, or from I/O operations to the underlying server) and cancellation to discard in-flight data that was in the process of being written when the error took place.

Parameters:

data - the data to be released

Since:

5.0.11