Package org.elasticsearch.action

Class StepListener<Response>

java.lang.Object
org.elasticsearch.action.NotifyOnceListener<Response>
org.elasticsearch.action.StepListener<Response>
All Implemented Interfaces:
ActionListener<Response>
public final class StepListener<Response>
extends NotifyOnceListener<Response>
A StepListener provides a simple way to write a flow consisting of multiple asynchronous steps without having nested callbacks. For example: 

  void asyncFlowMethod(... ActionListener<R> flowListener) {
    StepListener<R1> step1 = new StepListener<>();
    asyncStep1(..., step1);

    StepListener<R2> step2 = new StepListener<>();
    step1.whenComplete(r1 -> {
      asyncStep2(r1, ..., step2);
    }, flowListener::onFailure);

    step2.whenComplete(r2 -> {
      R1 r1 = step1.result();
      R r = combine(r1, r2);
     flowListener.onResponse(r);
    }, flowListener::onFailure);
  }

  • Constructor Summary

    Constructors 
    Constructor Description
    StepListener()  

  • Method Summary

    Modifier and Type Method Description
    protected void innerOnFailure​(java.lang.Exception e)  
    protected void innerOnResponse​(Response response)  
    Response result()
    Gets the result of this step.
    void whenComplete​(CheckedConsumer<Response,​java.lang.Exception> onResponse, java.util.function.Consumer<java.lang.Exception> onFailure)
    Registers the given actions which are called when this step is completed.

    Methods inherited from class org.elasticsearch.action.NotifyOnceListener

    onFailure, onResponse

    Methods inherited from class java.lang.Object

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

  • Constructor Details

  • Method Details

    • innerOnResponse

      protected void innerOnResponse​(Response response)
      Specified by:
      innerOnResponse in class NotifyOnceListener<Response>

    • innerOnFailure

      protected void innerOnFailure​(java.lang.Exception e)
      Specified by:
      innerOnFailure in class NotifyOnceListener<Response>

    • whenComplete

      public void whenComplete​(CheckedConsumer<Response,​java.lang.Exception> onResponse, java.util.function.Consumer<java.lang.Exception> onFailure)
      Registers the given actions which are called when this step is completed. If this step is completed successfully, the onResponse is called with the result; otherwise the onFailure is called with the failure.
      Parameters:
      onResponse - is called when this step is completed successfully
      onFailure - is called when this step is completed with a failure

    • result

      public Response result()
      Gets the result of this step. This method will throw IllegalStateException if this step is not completed yet.