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 * 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.channel;
17
18 import io.netty.buffer.ByteBuf;
19 import io.netty.buffer.ByteBufHolder;
20
21 /**
22 * Default {@link MessageSizeEstimator} implementation which supports the estimation of the size of
23 * {@link ByteBuf}, {@link ByteBufHolder} and {@link FileRegion}.
24 */
25 public final class DefaultMessageSizeEstimator implements MessageSizeEstimator {
26
27 private static final class HandleImpl implements Handle {
28 private final int unknownSize;
29
30 private HandleImpl(int unknownSize) {
31 this.unknownSize = unknownSize;
32 }
33
34 @Override
35 public int size(Object msg) {
36 if (msg instanceof ByteBuf) {
37 return ((ByteBuf) msg).readableBytes();
38 }
39 if (msg instanceof ByteBufHolder) {
40 return ((ByteBufHolder) msg).content().readableBytes();
41 }
42 if (msg instanceof FileRegion) {
43 return 0;
44 }
45 return unknownSize;
46 }
47 }
48
49 /**
50 * Return the default implementation which returns {@code 8} for unknown messages.
51 */
52 public static final MessageSizeEstimator DEFAULT = new DefaultMessageSizeEstimator(8);
53
54 private final Handle handle;
55
56 /**
57 * Create a new instance
58 *
59 * @param unknownSize The size which is returned for unknown messages.
60 */
61 public DefaultMessageSizeEstimator(int unknownSize) {
62 if (unknownSize < 0) {
63 throw new IllegalArgumentException("unknownSize: " + unknownSize + " (expected: >= 0)");
64 }
65 handle = new HandleImpl(unknownSize);
66 }
67
68 @Override
69 public Handle newHandle() {
70 return handle;
71 }
72 }