1 /*
2 * ====================================================================
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing,
14 * software distributed under the License is distributed on an
15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16 * KIND, either express or implied. See the License for the
17 * specific language governing permissions and limitations
18 * under the License.
19 * ====================================================================
20 *
21 * This software consists of voluntary contributions made by many
22 * individuals on behalf of the Apache Software Foundation. For more
23 * information on the Apache Software Foundation, please see
24 * <http://www.apache.org/>.
25 *
26 */
27 package org.apache.hc.core5.concurrent;
28
29 /**
30 * Abstracts implementations of {@link FutureCallback}s that contribute a result
31 * of the operation to another {@link FutureCallback}.
32 *
33 * @param <T> the future result type of an asynchronous operation.
34 * @since 5.1
35 */
36 public abstract class CallbackContribution<T> implements FutureCallback<T> {
37
38 private final FutureCallback<?> callback;
39
40 /**
41 * Constructs a new instance for a FutureCallback.
42 *
43 * @param callback the FutureCallback, may be {@code null}.
44 */
45 public CallbackContribution(final FutureCallback<?> callback) {
46 this.callback = callback;
47 }
48
49 @Override
50 public final void failed(final Exception ex) {
51 if (callback != null) {
52 callback.failed(ex);
53 }
54 }
55
56 @Override
57 public final void cancelled() {
58 if (callback != null) {
59 callback.cancelled();
60 }
61 }
62
63 }