Package org.elasticsearch.action

Class StepListener<Response>

  • All Implemented Interfaces:
    ActionListener<Response>
    public final class StepListener<Response>
extends java.lang.Object
implements ActionListener<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
      void onFailure​(java.lang.Exception e)
      A failure caused by an exception at some phase of the task.
      void onResponse​(Response response)
      Handle action 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 java.lang.Object

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

    • Constructor Detail

      • StepListener

        public StepListener()

    • Method Detail

      • onResponse

        public void onResponse​(Response response)
        Description copied from interface: ActionListener
        Handle action response. This response may constitute a failure or a success but it is up to the listener to make that decision.
        Specified by:
        onResponse in interface ActionListener<Response>

      • onFailure

        public void onFailure​(java.lang.Exception e)
        Description copied from interface: ActionListener
        A failure caused by an exception at some phase of the task.
        Specified by:
        onFailure in interface ActionListener<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.