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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      static IoEventQueueHandler NOOP = new IoEventQueueHandler() {
    38          public boolean accept(Object source, IoEvent event) {
    39              return true;
    40          }
    41
    42          public void offered(Object source, IoEvent event) {
    43              // NOOP
    44          }
    45
    46          public void polled(Object source, IoEvent event) {
    47              // NOOP
    48          }
    49      };
    50
    51      /**
    52       * Returns <tt>true</tt> if and only if the specified <tt>event</tt> is
    53       * allowed to be offered to the event queue.  The <tt>event</tt> is dropped
    54       * if <tt>false</tt> is returned.
    55       */
    56      boolean accept(Object source, IoEvent event);
    57
    58      /**
    59       * Invoked after the specified <tt>event</tt> has been offered to the
    60       * event queue.
    61       */
    62      void offered(Object source, IoEvent event);
    63
    64      /**
    65       * Invoked after the specified <tt>event</tt> has been polled from the
    66       * event queue.
    67       */
    68      void polled(Object source, IoEvent event);
    69  }