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 import java.util.concurrent.Future;
30 import java.util.concurrent.atomic.AtomicReference;
31
32 import org.apache.hc.core5.util.Args;
33
34 /**
35 * {@link Future} whose result depends on another {@link Cancellable} process
36 * or operation or another {@link Future}. Dependent process will get cancelled
37 * if the future itself is cancelled.
38 *
39 * @param <T> the future result type of an asynchronous operation.
40 * @since 5.0
41 */
42 public final class ComplexFuture<T> extends BasicFuture<T> implements CancellableDependency {
43
44 private final AtomicReference<Cancellable> dependencyRef;
45
46 public ComplexFuture(final FutureCallback<T> callback) {
47 super(callback);
48 this.dependencyRef = new AtomicReference<>(null);
49 }
50
51 @Override
52 public void setDependency(final Cancellable dependency) {
53 Args.notNull(dependency, "dependency");
54 if (isDone()) {
55 dependency.cancel();
56 } else {
57 dependencyRef.set(dependency);
58 }
59 }
60
61 public void setDependency(final Future<?> dependency) {
62 Args.notNull(dependency, "dependency");
63 if (dependency instanceof Cancellable) {
64 setDependency((Cancellable) dependency);
65 } else {
66 setDependency(new Cancellable() {
67
68 @Override
69 public boolean cancel() {
70 return dependency.cancel(true);
71 }
72
73 });
74 }
75 }
76
77 @Override
78 public boolean completed(final T result) {
79 final boolean completed = super.completed(result);
80 dependencyRef.set(null);
81 return completed;
82 }
83
84 @Override
85 public boolean failed(final Exception exception) {
86 final boolean failed = super.failed(exception);
87 dependencyRef.set(null);
88 return failed;
89 }
90
91 @Override
92 public boolean cancel(final boolean mayInterruptIfRunning) {
93 final boolean cancelled = super.cancel(mayInterruptIfRunning);
94 final Cancellable dependency = dependencyRef.getAndSet(null);
95 if (dependency != null) {
96 dependency.cancel();
97 }
98 return cancelled;
99 }
100
101 }