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1   /*
2    * Copyright 2016 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.util.concurrent;
17  
18  import io.netty.util.internal.ObjectUtil;
19  import io.netty.util.internal.logging.InternalLogger;
20  import io.netty.util.internal.logging.InternalLoggerFactory;
21  
22  public final class UnaryPromiseNotifier<T> implements FutureListener<T> {
23      private static final InternalLogger logger = InternalLoggerFactory.getInstance(UnaryPromiseNotifier.class);
24      private final Promise<? super T> promise;
25  
26      public UnaryPromiseNotifier(Promise<? super T> promise) {
27          this.promise = ObjectUtil.checkNotNull(promise, "promise");
28      }
29  
30      @Override
31      public void operationComplete(Future<T> future) throws Exception {
32          cascadeTo(future, promise);
33      }
34  
35      public static <X> void cascadeTo(Future<X> completedFuture, Promise<? super X> promise) {
36          if (completedFuture.isSuccess()) {
37              if (!promise.trySuccess(completedFuture.getNow())) {
38                  logger.warn("Failed to mark a promise as success because it is done already: {}", promise);
39              }
40          } else if (completedFuture.isCancelled()) {
41              if (!promise.cancel(false)) {
42                  logger.warn("Failed to cancel a promise because it is done already: {}", promise);
43              }
44          } else {
45              if (!promise.tryFailure(completedFuture.cause())) {
46                  logger.warn("Failed to mark a promise as failure because it's done already: {}", promise,
47                              completedFuture.cause());
48              }
49          }
50      }
51  }