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1   /*
2    * Copyright 2013 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    *   https://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.netty5.channel;
17  
18  import io.netty5.buffer.api.Buffer;
19  
20  import static io.netty5.util.internal.ObjectUtil.checkPositiveOrZero;
21  
22  /**
23   * Default {@link MessageSizeEstimator} implementation which supports the estimation of the size of
24   * {@link Buffer} and {@link FileRegion}.
25   */
26  public final class DefaultMessageSizeEstimator implements MessageSizeEstimator {
27  
28      private static final class HandleImpl implements Handle {
29          private final int unknownSize;
30  
31          private HandleImpl(int unknownSize) {
32              this.unknownSize = unknownSize;
33          }
34  
35          @Override
36          public int size(Object msg) {
37              if (msg instanceof Buffer) {
38                  return ((Buffer) msg).readableBytes();
39              }
40              if (msg instanceof FileRegion) {
41                  return 0;
42              }
43              return unknownSize;
44          }
45      }
46  
47      /**
48       * Return the default implementation which returns {@code 8} for unknown messages.
49       */
50      public static final MessageSizeEstimator DEFAULT = new DefaultMessageSizeEstimator(8);
51  
52      private final Handle handle;
53  
54      /**
55       * Create a new instance
56       *
57       * @param unknownSize       The size which is returned for unknown messages.
58       */
59      public DefaultMessageSizeEstimator(int unknownSize) {
60          checkPositiveOrZero(unknownSize, "unknownSize");
61          handle = new HandleImpl(unknownSize);
62      }
63  
64      @Override
65      public Handle newHandle() {
66          return handle;
67      }
68  }