1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.mina.filter.codec;
21
22 import org.apache.mina.core.buffer.IoBuffer;
23 import org.apache.mina.core.session.IoSession;
24
25 /**
26 * A {@link ProtocolDecoder} implementation which decorates an existing decoder
27 * to be thread-safe. Please be careful if you're going to use this decorator
28 * because it can be a root of performance degradation in a multi-thread
29 * environment. Also, by default, appropriate synchronization is done
30 * on a per-session basis by {@link ProtocolCodecFilter}. Please use this
31 * decorator only when you need to synchronize on a per-decoder basis, which
32 * is not common.
33 *
34 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
35 */
36 public class SynchronizedProtocolDecoder implements ProtocolDecoder {
37 private final ProtocolDecoder decoder;
38
39 /**
40 * Creates a new instance which decorates the specified <tt>decoder</tt>.
41 *
42 * @param decoder The decorated decoder
43 */
44 public SynchronizedProtocolDecoder(ProtocolDecoder decoder) {
45 if (decoder == null) {
46 throw new IllegalArgumentException("decoder");
47 }
48
49 this.decoder = decoder;
50 }
51
52 /**
53 * @return the decoder this decoder is decorating.
54 */
55 public ProtocolDecoder getDecoder() {
56 return decoder;
57 }
58
59 /**
60 * {@inheritDoc}
61 */
62 @Override
63 public void decode(IoSession session, IoBuffer in, ProtocolDecoderOutput out) throws Exception {
64 synchronized (decoder) {
65 decoder.decode(session, in, out);
66 }
67 }
68
69 /**
70 * {@inheritDoc}
71 */
72 @Override
73 public void finishDecode(IoSession session, ProtocolDecoderOutput out) throws Exception {
74 synchronized (decoder) {
75 decoder.finishDecode(session, out);
76 }
77 }
78
79 /**
80 * {@inheritDoc}
81 */
82 @Override
83 public void dispose(IoSession session) throws Exception {
84 synchronized (decoder) {
85 decoder.dispose(session);
86 }
87 }
88 }