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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.common.ByteBuffer;
    23  import org.apache.mina.common.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 The Apache Directory Project (mina-dev@directory.apache.org)
    35   * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (Fri, 13 Jul 2007) $
    36   */
    37  public class SynchronizedProtocolDecoder implements ProtocolDecoder {
    38      private final ProtocolDecoder decoder;
    39
    40      /**
    41       * Creates a new instance which decorates the specified <tt>decoder</tt>.
    42       */
    43      public SynchronizedProtocolDecoder(ProtocolDecoder decoder) {
    44          if (decoder == null) {
    45              throw new NullPointerException("decoder");
    46          }
    47          this.decoder = decoder;
    48      }
    49
    50      /**
    51       * Returns the decoder this decoder is decorating.
    52       */
    53      public ProtocolDecoder getDecoder() {
    54          return decoder;
    55      }
    56
    57      public void decode(IoSession session, ByteBuffer in,
    58              ProtocolDecoderOutput out) throws Exception {
    59          synchronized (decoder) {
    60              decoder.decode(session, in, out);
    61          }
    62      }
    63
    64      public void finishDecode(IoSession session, ProtocolDecoderOutput out)
    65              throws Exception {
    66          synchronized (decoder) {
    67              decoder.finishDecode(session, out);
    68          }
    69      }
    70
    71      public void dispose(IoSession session) throws Exception {
    72          synchronized (decoder) {
    73              decoder.dispose(session);
    74          }
    75      }
    76  }