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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.session.IoSession;
23  
24  /**
25   * A {@link ProtocolEncoder} implementation which decorates an existing encoder
26   * to be thread-safe.  Please be careful if you're going to use this decorator
27   * because it can be a root of performance degradation in a multi-thread
28   * environment.  Please use this decorator only when you need to synchronize
29   * on a per-encoder basis instead of on a per-session basis, which is not
30   * common.
31   *
32   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
33   */
34  public class SynchronizedProtocolEncoder implements ProtocolEncoder {
35      private final ProtocolEncoder encoder;
36  
37      /**
38       * Creates a new instance which decorates the specified <tt>encoder</tt>.
39       */
40      public SynchronizedProtocolEncoder(ProtocolEncoder encoder) {
41          if (encoder == null) {
42              throw new IllegalArgumentException("encoder");
43          }
44          this.encoder = encoder;
45      }
46  
47      /**
48       * Returns the encoder this encoder is decorating.
49       */
50      public ProtocolEncoder getEncoder() {
51          return encoder;
52      }
53  
54      public void encode(IoSession session, Object message, ProtocolEncoderOutput out) throws Exception {
55          synchronized (encoder) {
56              encoder.encode(session, message, out);
57          }
58      }
59  
60      public void dispose(IoSession session) throws Exception {
61          synchronized (encoder) {
62              encoder.dispose(session);
63          }
64      }
65  }