| // |
| // ======================================================================== |
| // Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd. |
| // ------------------------------------------------------------------------ |
| // All rights reserved. This program and the accompanying materials |
| // are made available under the terms of the Eclipse Public License v1.0 |
| // and Apache License v2.0 which accompanies this distribution. |
| // |
| // The Eclipse Public License is available at |
| // http://www.eclipse.org/legal/epl-v10.html |
| // |
| // The Apache License v2.0 is available at |
| // http://www.opensource.org/licenses/apache2.0.php |
| // |
| // You may elect to redistribute this code under either of these licenses. |
| // ======================================================================== |
| // |
| |
| package org.eclipse.jetty.util; |
| |
| /** |
| * <p>A callback abstraction that handles completed/failed events of asynchronous operations.</p> |
| * |
| * <p>Semantically this is equivalent to an optimise Promise<Void>, but callback is a more meaningful |
| * name than EmptyPromise</p> |
| */ |
| public interface Callback |
| { |
| /** |
| * <p>Callback invoked when the operation completes.</p> |
| * |
| * @see #failed(Throwable) |
| */ |
| public abstract void succeeded(); |
| |
| /** |
| * <p>Callback invoked when the operation fails.</p> |
| * @param x the reason for the operation failure |
| */ |
| public void failed(Throwable x); |
| |
| /** |
| * <p>Empty implementation of {@link Callback}</p> |
| */ |
| public static class Adapter implements Callback |
| { |
| /** |
| * Instance of Adapter that can be used when the callback methods need an empty |
| * implementation without incurring in the cost of allocating a new Adapter object. |
| */ |
| public static final Adapter INSTANCE = new Adapter(); |
| |
| @Override |
| public void succeeded() |
| { |
| } |
| |
| @Override |
| public void failed(Throwable x) |
| { |
| } |
| } |
| } |