2 // ========================================================================
3 // Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
4 // ------------------------------------------------------------------------
5 // All rights reserved. This program and the accompanying materials
6 // are made available under the terms of the Eclipse Public License v1.0
7 // and Apache License v2.0 which accompanies this distribution.
9 // The Eclipse Public License is available at
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12 // The Apache License v2.0 is available at
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15 // You may elect to redistribute this code under either of these licenses.
16 // ========================================================================
19 package org.eclipse.jetty.util;
22 * <p>A callback abstraction that handles completed/failed events of asynchronous operations.</p>
24 * <p>Semantically this is equivalent to an optimise Promise<Void>, but callback is a more meaningful
25 * name than EmptyPromise</p>
27 public interface Callback
30 * <p>Callback invoked when the operation completes.</p>
32 * @see #failed(Throwable)
34 public abstract void succeeded();
37 * <p>Callback invoked when the operation fails.</p>
38 * @param x the reason for the operation failure
40 public void failed(Throwable x);
43 * <p>Empty implementation of {@link Callback}</p>
45 public static class Adapter implements Callback
48 * Instance of Adapter that can be used when the callback methods need an empty
49 * implementation without incurring in the cost of allocating a new Adapter object.
51 public static final Adapter INSTANCE = new Adapter();
54 public void succeeded()
59 public void failed(Throwable x)