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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;
    21
    22  import org.apache.mina.common.IdleStatus;
    23  import org.apache.mina.common.IoFilter;
    24  import org.apache.mina.common.IoFilterChain;
    25  import org.apache.mina.common.IoSession;
    26
    27  /**
    28   * An {@link IoFilter}s wrapper that keeps track of the number of usages of this filter and will call init/destroy
    29   * when the filter is not in use.
    30   *
    31   * @author The Apache Directory Project (mina-dev@directory.apache.org)
    32   * @version $Rev: 587373 $, $Date: 2007-10-23 04:54:05 +0200 (Tue, 23 Oct 2007) $
    33   */
    34  public class ReferenceCountingIoFilter implements IoFilter {
    35      private final IoFilter filter;
    36
    37      private int count = 0;
    38
    39      public ReferenceCountingIoFilter(IoFilter filter) {
    40          this.filter = filter;
    41      }
    42
    43      public void init() throws Exception {
    44          // no-op, will init on-demand in pre-add if count == 0
    45      }
    46
    47      public void destroy() throws Exception {
    48          //no-op, will destroy on-demand in post-remove if count == 0
    49      }
    50
    51      public synchronized void onPreAdd(IoFilterChain parent, String name,
    52              NextFilter nextFilter) throws Exception {
    53          if (0 == count) {
    54              filter.init();
    55
    56              ++count;
    57          }
    58
    59          filter.onPreAdd(parent, name, nextFilter);
    60      }
    61
    62      public synchronized void onPostRemove(IoFilterChain parent, String name,
    63              NextFilter nextFilter) throws Exception {
    64          filter.onPostRemove(parent, name, nextFilter);
    65
    66          --count;
    67
    68          if (0 == count) {
    69              filter.destroy();
    70          }
    71      }
    72
    73      public void exceptionCaught(NextFilter nextFilter, IoSession session,
    74              Throwable cause) throws Exception {
    75          filter.exceptionCaught(nextFilter, session, cause);
    76      }
    77
    78      public void filterClose(NextFilter nextFilter, IoSession session)
    79              throws Exception {
    80          filter.filterClose(nextFilter, session);
    81      }
    82
    83      public void filterWrite(NextFilter nextFilter, IoSession session,
    84              WriteRequest writeRequest) throws Exception {
    85          filter.filterWrite(nextFilter, session, writeRequest);
    86      }
    87
    88      public void messageReceived(NextFilter nextFilter, IoSession session,
    89              Object message) throws Exception {
    90          filter.messageReceived(nextFilter, session, message);
    91      }
    92
    93      public void messageSent(NextFilter nextFilter, IoSession session,
    94              Object message) throws Exception {
    95          filter.messageSent(nextFilter, session, message);
    96      }
    97
    98      public void onPostAdd(IoFilterChain parent, String name,
    99              NextFilter nextFilter) throws Exception {
    100         filter.onPostAdd(parent, name, nextFilter);
    101     }
    102
    103     public void onPreRemove(IoFilterChain parent, String name,
    104             NextFilter nextFilter) throws Exception {
    105         filter.onPreRemove(parent, name, nextFilter);
    106     }
    107
    108     public void sessionClosed(NextFilter nextFilter, IoSession session)
    109             throws Exception {
    110         filter.sessionClosed(nextFilter, session);
    111     }
    112
    113     public void sessionCreated(NextFilter nextFilter, IoSession session)
    114             throws Exception {
    115         filter.sessionCreated(nextFilter, session);
    116     }
    117
    118     public void sessionIdle(NextFilter nextFilter, IoSession session,
    119             IdleStatus status) throws Exception {
    120         filter.sessionIdle(nextFilter, session, status);
    121     }
    122
    123     public void sessionOpened(NextFilter nextFilter, IoSession session)
    124             throws Exception {
    125         filter.sessionOpened(nextFilter, session);
    126     }
    127 }