View Javadoc

    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      public SynchronizedProtocolDecoder(ProtocolDecoder decoder) {
    43          if (decoder == null) {
    44              throw new IllegalArgumentException("decoder");
    45          }
    46          this.decoder = decoder;
    47      }
    48
    49      /**
    50       * Returns the decoder this decoder is decorating.
    51       */
    52      public ProtocolDecoder getDecoder() {
    53          return decoder;
    54      }
    55
    56      public void decode(IoSession session, IoBuffer in, ProtocolDecoderOutput out) throws Exception {
    57          synchronized (decoder) {
    58              decoder.decode(session, in, out);
    59          }
    60      }
    61
    62      public void finishDecode(IoSession session, ProtocolDecoderOutput out) throws Exception {
    63          synchronized (decoder) {
    64              decoder.finishDecode(session, out);
    65          }
    66      }
    67
    68      public void dispose(IoSession session) throws Exception {
    69          synchronized (decoder) {
    70              decoder.dispose(session);
    71          }
    72      }
    73  }