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
28 package org.apache.hc.client5.http.impl;
29
30 import java.util.concurrent.ExecutionException;
31 import java.util.concurrent.Future;
32 import java.util.concurrent.TimeUnit;
33 import java.util.concurrent.TimeoutException;
34
35 import org.apache.hc.core5.concurrent.Cancellable;
36
37 /**
38 * Common cancellable operations.
39 *
40 * @since 5.0
41 */
42 public final class Operations {
43
44 private final static Cancellable NOOP_CANCELLABLE = () -> false;
45
46 /**
47 * This class represents a {@link Future} in the completed state with a fixed result.
48 * The outcome of the future cannot be altered and it cannot be cancelled.
49 *
50 * @param <T> operation result representation.
51 *
52 * @deprecated Use {@link org.apache.hc.core5.concurrent.CompletedFuture}.
53 */
54 @Deprecated
55 public static class CompletedFuture<T> implements Future<T> {
56
57 private final T result;
58
59 public CompletedFuture(final T result) {
60 this.result = result;
61 }
62
63 @Override
64 public T get() throws InterruptedException, ExecutionException {
65 return result;
66 }
67
68 @Override
69 public T get(final long timeout, final TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
70 return result;
71 }
72 @Override
73 public boolean cancel(final boolean mayInterruptIfRunning) {
74 return false;
75 }
76
77 @Override
78 public boolean isCancelled() {
79 return false;
80 }
81
82 @Override
83 public boolean isDone() {
84 return true;
85 }
86
87 }
88
89 /**
90 * Creates a {@link Cancellable} operation handle for an ongoing process
91 * or operation that cannot be cancelled. Attempts to cancel the operation
92 * with this handle will have no effect.
93 *
94 * @return the no-op cancellable operation handle.
95 */
96 public static Cancellable nonCancellable() {
97 return NOOP_CANCELLABLE;
98 }
99
100 /**
101 * Creates a {@link Cancellable} operation handle for an ongoing process
102 * or operation represented by a {@link Future}.
103 *
104 * @param future the result future
105 * @return the cancellable operation handle.
106 */
107 public static Cancellable cancellable(final Future<?> future) {
108 if (future == null) {
109 return NOOP_CANCELLABLE;
110 }
111 if (future instanceof Cancellable) {
112 return (Cancellable) future;
113 }
114 return () -> future.cancel(true);
115 }
116
117 }