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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.executor;
21  
22  import java.util.EventListener;
23  
24  import org.apache.mina.core.session.IoEvent;
25  
26  /**
27   * Listens and filters all event queue operations occurring in
28   * {@link OrderedThreadPoolExecutor} and {@link UnorderedThreadPoolExecutor}.
29   *
30   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
31   */
32  public interface IoEventQueueHandler extends EventListener {
33  
34      /**
35       * A dummy handler which always accepts event doing nothing particular.
36       */
37      IoEventQueueHandler NOOP = new IoEventQueueHandler() {
38          /**
39           * {@inheritDoc}
40           */
41          @Override
42          public boolean accept(Object source, IoEvent event) {
43              return true;
44          }
45  
46          /**
47           * {@inheritDoc}
48           */
49          @Override
50          public void offered(Object source, IoEvent event) {
51              // NOOP
52          }
53  
54          /**
55           * {@inheritDoc}
56           */
57          @Override
58          public void polled(Object source, IoEvent event) {
59              // NOOP
60          }
61      };
62  
63      /**
64       * @return <tt>true</tt> if and only if the specified <tt>event</tt> is
65       * allowed to be offered to the event queue.  The <tt>event</tt> is dropped
66       * if <tt>false</tt> is returned.
67       * 
68       * @param source The source of event
69       * @param event The received event
70       */
71      boolean accept(Object source, IoEvent event);
72  
73      /**
74       * Invoked after the specified <tt>event</tt> has been offered to the
75       * event queue.
76       * 
77       * @param source The source of event
78       * @param event The received event
79       */
80      void offered(Object source, IoEvent event);
81  
82      /**
83       * Invoked after the specified <tt>event</tt> has been polled from the
84       * event queue.
85       * 
86       * @param source The source of event
87       * @param event The received event
88       */
89      void polled(Object source, IoEvent event);
90  }