Package org.elasticsearch.action

Interface ActionListener<Response>

All Known Subinterfaces:
PersistentTasksService.WaitForPersistentTaskListener<P>, RejectAwareActionListener<T>
All Known Implementing Classes:
ActionListener.Delegating, ActionListener.DelegatingActionListener, ActionListener.DelegatingFailureActionListener, ActionListener.MappedActionListener, ActionListener.RunAfterActionListener, ActionListener.RunBeforeActionListener, AdapterActionFuture, ChannelActionListener, ContextPreservingActionListener, DispatchingRestToXContentListener, GetSnapshotInfoContext, GroupedActionListener, LatchedActionListener, ListenableActionFuture, ListenableFuture, NotifyOnceListener, PlainActionFuture, RestActionListener, RestActions.NodesResponseRestListener, RestBuilderListener, RestResponseListener, RestStatusToXContentListener, RestToXContentListener, SearchExecutionStatsCollector, SearchProgressActionListener, SnapshotShardContext, StepListener, ThreadedActionListener
public interface ActionListener<Response>
A listener for action responses or failures.

  • Method Details

    • onResponse

      void onResponse(Response response)
      Handle action response. This response may constitute a failure or a success but it is up to the listener to make that decision.

    • onFailure

      void onFailure(Exception e)
      A failure caused by an exception at some phase of the task.

    • map

      default <T> ActionListener<T> map(org.elasticsearch.core.CheckedFunction<T,Response,Exception> fn)
      Creates a listener that wraps this listener, mapping response values via the given mapping function and passing along exceptions to this instance. Notice that it is considered a bug if the listener's onResponse or onFailure fails. onResponse failures will not call onFailure. If the function fails, the listener's onFailure handler will be called. The principle is that the mapped listener will handle exceptions from the mapping function fn but it is the responsibility of delegate to handle its own exceptions inside `onResponse` and `onFailure`.
      Type Parameters:
      T - Response type of the wrapped listener
      Parameters:
      fn - Function to apply to listener response
      Returns:
      a listener that maps the received response and then passes it to this instance

    • wrap

      static <Response> ActionListener<Response> wrap(org.elasticsearch.core.CheckedConsumer<Response,? extends Exception> onResponse, Consumer<Exception> onFailure)
      Creates a listener that listens for a response (or failure) and executes the corresponding consumer when the response (or failure) is received.
      Type Parameters:
      Response - the type of the response
      Parameters:
      onResponse - the checked consumer of the response, when the listener receives one
      onFailure - the consumer of the failure, when the listener receives one
      Returns:
      a listener that listens for responses and invokes the consumer when received

    • delegateResponse

      default ActionListener<Response> delegateResponse(BiConsumer<ActionListener<Response>,Exception> bc)
      Creates a listener that delegates all responses it receives to this instance.
      Parameters:
      bc - BiConsumer invoked with delegate listener and exception
      Returns:
      Delegating listener

    • delegateFailure

      default <T> ActionListener<T> delegateFailure(BiConsumer<ActionListener<Response>,T> bc)
      Creates a listener that delegates all exceptions it receives to another listener.
      Type Parameters:
      T - Type of the delegating listener's response
      Parameters:
      bc - BiConsumer invoked with delegate listener and response
      Returns:
      Delegating listener

    • wrap

      static <Response> ActionListener<Response> wrap(Runnable runnable)
      Creates a listener that listens for a response (or failure) and executes the corresponding runnable when the response (or failure) is received.
      Type Parameters:
      Response - the type of the response
      Parameters:
      runnable - the runnable that will be called in event of success or failure
      Returns:
      a listener that listens for responses and invokes the runnable when received

    • toBiConsumer

      static <Response> BiConsumer<Response,Exception> toBiConsumer(ActionListener<Response> listener)
      Converts a listener to a BiConsumer for compatibility with the CompletableFuture api.
      Type Parameters:
      Response - the type of the response
      Parameters:
      listener - that will be wrapped
      Returns:
      a bi consumer that will complete the wrapped listener

    • onResponse

      static <Response> void onResponse(Iterable<ActionListener<Response>> listeners, Response response)
      Notifies every given listener with the response passed to onResponse(Object). If a listener itself throws an exception the exception is forwarded to onFailure(Exception). If in turn onFailure(Exception) fails all remaining listeners will be processed and the caught exception will be re-thrown.

    • onFailure

      static <Response> void onFailure(Iterable<ActionListener<Response>> listeners, Exception failure)
      Notifies every given listener with the failure passed to onFailure(Exception). If a listener itself throws an exception all remaining listeners will be processed and the caught exception will be re-thrown.

    • runAfter

      static <Response> ActionListener<Response> runAfter(ActionListener<Response> delegate, Runnable runAfter)
      Wraps a given listener and returns a new listener which executes the provided runAfter callback when the listener is notified via either #onResponse or #onFailure.

    • runBefore

      static <Response> ActionListener<Response> runBefore(ActionListener<Response> delegate, org.elasticsearch.core.CheckedRunnable<?> runBefore)
      Wraps a given listener and returns a new listener which executes the provided runBefore callback before the listener is notified via either #onResponse or #onFailure. If the callback throws an exception then it will be passed to the listener's #onFailure and its #onResponse will not be executed.

    • notifyOnce

      static <Response> ActionListener<Response> notifyOnce(ActionListener<Response> delegate)
      Wraps a given listener and returns a new listener which makes sure onResponse(Object) and onFailure(Exception) of the provided listener will be called at most once.

    • completeWith

      static <Response> void completeWith(ActionListener<Response> listener, CheckedSupplier<Response,? extends Exception> supplier)
      Completes the given listener with the result from the provided supplier accordingly. This method is mainly used to complete a listener with a block of synchronous code. If the supplier fails, the listener's onFailure handler will be called. It is the responsibility of delegate to handle its own exceptions inside `onResponse` and `onFailure`.