1 //
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.
8 //
9 // The Eclipse Public License is available at
10 // http://www.eclipse.org/legal/epl-v10.html
11 //
12 // The Apache License v2.0 is available at
13 // http://www.opensource.org/licenses/apache2.0.php
14 //
15 // You may elect to redistribute this code under either of these licenses.
16 // ========================================================================
17 //
18
19 package org.eclipse.jetty.util;
20
21 import org.eclipse.jetty.util.log.Log;
22
23 /**
24 * <p>A callback abstraction that handles completed/failed events of asynchronous operations.</p>
25 *
26 * @param <C> the type of the context object
27 */
28 public interface Promise<C>
29 {
30 /**
31 * <p>Callback invoked when the operation completes.</p>
32 *
33 * @param result the context
34 * @see #failed(Throwable)
35 */
36 public abstract void succeeded(C result);
37
38 /**
39 * <p>Callback invoked when the operation fails.</p>
40 *
41 * @param x the reason for the operation failure
42 */
43 public void failed(Throwable x);
44
45
46 /**
47 * <p>Empty implementation of {@link Promise}</p>
48 *
49 * @param <C> the type of the context object
50 */
51 public static class Adapter<C> implements Promise<C>
52 {
53 @Override
54 public void succeeded(C result)
55 {
56 }
57
58 @Override
59 public void failed(Throwable x)
60 {
61 Log.getLogger(this.getClass()).warn(x);
62 }
63 }
64
65 }