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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.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 The Apache Directory Project (mina-dev@directory.apache.org)
    33   * @version $Rev: 555855 $, $Date: 2007-07-13 05:19:00 +0200 (Fri, 13 Jul 2007) $
    34   */
    35  public class SynchronizedProtocolEncoder implements ProtocolEncoder {
    36      private final ProtocolEncoder encoder;
    37
    38      /**
    39       * Creates a new instance which decorates the specified <tt>encoder</tt>.
    40       */
    41      public SynchronizedProtocolEncoder(ProtocolEncoder encoder) {
    42          if (encoder == null) {
    43              throw new NullPointerException("encoder");
    44          }
    45          this.encoder = encoder;
    46      }
    47
    48      /**
    49       * Returns the encoder this encoder is decorating.
    50       */
    51      public ProtocolEncoder getEncoder() {
    52          return encoder;
    53      }
    54
    55      public void encode(IoSession session, Object message,
    56              ProtocolEncoderOutput out) throws Exception {
    57          synchronized (encoder) {
    58              encoder.encode(session, message, out);
    59          }
    60      }
    61
    62      public void dispose(IoSession session) throws Exception {
    63          synchronized (encoder) {
    64              encoder.dispose(session);
    65          }
    66      }
    67  }