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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  }