org.springframework.http.server.reactive

Class AbstractListenerReadPublisher<T>

java.lang.Object

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

Type Parameters:

T - the type of element signaled

Direct Known Subclasses:

AbstractListenerWebSocketSession.WebSocketReceivePublisher, ServletServerHttpRequest.RequestBodyPublisher, UndertowServerHttpRequest.RequestBodyPublisher

public abstract class AbstractListenerReadPublisher<T>
extends java.lang.Object

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

Specifically a base class for reading from the HTTP request body with Servlet 3.1 non-blocking I/O and Undertow XNIO as well as handling incoming WebSocket messages with standard Java WebSocket (JSR-356), Jetty, and Undertow.

Since:

5.0

Author:

Arjen Poutsma, Violeta Georgieva, Rossen Stoyanchev

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private class	AbstractListenerReadPublisher.ReadSubscription Subscription that delegates signals to State.
private static class	AbstractListenerReadPublisher.State Represents a state for the Publisher to be in.

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	completionBeforeDemand
private long	demand
private static java.util.concurrent.atomic.AtomicLongFieldUpdater<AbstractListenerReadPublisher>	DEMAND_FIELD_UPDATER
private java.lang.Throwable	errorBeforeDemand
private java.lang.String	logPrefix
protected static Log	rsReadLogger Special logger for debugging Reactive Streams signals.
private java.util.concurrent.atomic.AtomicReference<AbstractListenerReadPublisher.State>	state
private <any>	subscriber

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
private boolean	changeState(AbstractListenerReadPublisher.State oldState, AbstractListenerReadPublisher.State newState)
private void	changeToDemandState(AbstractListenerReadPublisher.State oldState)
protected abstract void	checkOnDataAvailable() Check if data is available and either call onDataAvailable() immediately or schedule a notification.
private Subscription	createSubscription()
protected abstract void	discardData() Invoked after an I/O read error from the underlying server or after a cancellation signal from the downstream consumer to allow sub-classes to discard any current cached data they might have.
java.lang.String	getLogPrefix() Return the configured log message prefix.
void	onAllDataRead() Sub-classes can call this method to delegate a contain notification when all data has been read.
void	onDataAvailable() Invoked when reading is possible, either in the same thread after a check via checkOnDataAvailable(), or as a callback from the underlying container.
void	onError(java.lang.Throwable ex) Sub-classes can call this to delegate container error notifications.
protected abstract T	read() Read once from the input, if possible.
private boolean	readAndPublish() Read and publish data one at a time until there is no more data, no more demand, or perhaps we completed in the mean time.
protected abstract void	readingPaused() Invoked when reading is paused due to a lack of demand.
void	subscribe(<any> subscriber)

Methods inherited from class java.lang.Object

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

Field Detail

rsReadLogger

protected static Log rsReadLogger

Special logger for debugging Reactive Streams signals.

See Also:

LogDelegateFactory.getHiddenLog(Class), AbstractListenerWriteProcessor.rsWriteLogger, AbstractListenerWriteFlushProcessor.rsWriteFlushLogger, WriteResultPublisher.rsWriteResultLogger

state

private final java.util.concurrent.atomic.AtomicReference<AbstractListenerReadPublisher.State> state

demand

private volatile long demand

DEMAND_FIELD_UPDATER

private static final java.util.concurrent.atomic.AtomicLongFieldUpdater<AbstractListenerReadPublisher> DEMAND_FIELD_UPDATER

subscriber

@Nullable
private volatile <any> subscriber

completionBeforeDemand

private volatile boolean completionBeforeDemand

errorBeforeDemand

@Nullable
private volatile java.lang.Throwable errorBeforeDemand

logPrefix

private final java.lang.String logPrefix

Constructor Detail

AbstractListenerReadPublisher

public AbstractListenerReadPublisher()

AbstractListenerReadPublisher

public AbstractListenerReadPublisher(java.lang.String logPrefix)

Create an instance with the given log prefix.

Since:

5.1

Method Detail

getLogPrefix

public java.lang.String getLogPrefix()

Return the configured log message prefix.

Since:

5.1

subscribe

public void subscribe(<any> subscriber)

onDataAvailable

public final void onDataAvailable()

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

onAllDataRead

public void onAllDataRead()

Sub-classes can call this method to delegate a contain notification when all data has been read.

onError

public final void onError(java.lang.Throwable ex)

Sub-classes can call this to delegate container error notifications.

checkOnDataAvailable

protected abstract void checkOnDataAvailable()

Check if data is available and either call onDataAvailable() immediately or schedule a notification.

read

@Nullable
protected abstract T read()
                             throws java.io.IOException

Read once from the input, if possible.

Returns:

the item that was read; or null

Throws:

java.io.IOException

readingPaused

protected abstract void readingPaused()

Invoked when reading is paused due to a lack of demand.

Note: This method is guaranteed not to compete with checkOnDataAvailable() so it can be used to safely suspend reading, if the underlying API supports it, i.e. without competing with an implicit call to resume via checkOnDataAvailable().

Since:

5.0.2

discardData

protected abstract void discardData()

Invoked after an I/O read error from the underlying server or after a cancellation signal from the downstream consumer to allow sub-classes to discard any current cached data they might have.

Since:

5.0.11

readAndPublish

private boolean readAndPublish()
                        throws java.io.IOException

Read and publish data one at a time until there is no more data, no more demand, or perhaps we completed in the mean time.

Returns:

true if there is more demand; false if there is no more demand or we have completed.

Throws:

java.io.IOException

changeState

private boolean changeState(AbstractListenerReadPublisher.State oldState,
                            AbstractListenerReadPublisher.State newState)

changeToDemandState

private void changeToDemandState(AbstractListenerReadPublisher.State oldState)

createSubscription

private Subscription createSubscription()