Package 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 non-blocking I/O and Undertow XNIO as well for writing WebSocket messages through the Jakarta WebSocket API (JSR-356), Jetty, and Undertow.

Since:
5.0
Author:
Arjen Poutsma, Violeta Georgieva, Rossen Stoyanchev

  • Field Summary

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

  • Constructor Summary

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

  • Method Summary

    Modifier and Type
    Method
    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.
    final void
    onComplete()
    Completion signal from the upstream, write Publisher.
    final void
    onError(Throwable ex)
    Error signal from the upstream, write Publisher.
    final void
    onNext(T data)
     
    final void
    onSubscribe(Subscription subscription)
     
    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.
    final 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 Details

  • Constructor Details

    • AbstractListenerWriteProcessor

      public AbstractListenerWriteProcessor()

    • AbstractListenerWriteProcessor

      public AbstractListenerWriteProcessor(String logPrefix)
      Create an instance with the given log prefix.
      Since:
      5.1

  • Method Details

    • 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<T>

    • 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