org.elasticsearch.action.ActionListener Maven / Gradle / Ivy

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Elasticsearch subproject :core

There is a newer version: 8.14.1

/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.elasticsearch.action;

import java.util.function.Consumer;

/**
 * A listener for action responses or failures.
 */
public 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.
     */
    void onResponse(Response response);

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

    /**
     * Creates a listener that listens for a response (or failure) and executes the
     * corresponding consumer when the response (or failure) is received.
     *
     * @param onResponse the consumer of the response, when the listener receives one
     * @param onFailure the consumer of the failure, when the listener receives one
     * @param  the type of the response
     * @return a listener that listens for responses and invokes the consumer when received
     */
    static  ActionListener wrap(Consumer onResponse, Consumer onFailure) {
        return new ActionListener() {
            @Override
            public void onResponse(Response response) {
                try {
                    onResponse.accept(response);
                } catch (Exception e) {
                    onFailure(e);
                }
            }

            @Override
            public void onFailure(Exception e) {
                onFailure.accept(e);
            }
        };
    }
}