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    1   /*
    2    * Copyright 2009 Red Hat, Inc.
    3    *
    4    * Red Hat licenses this file to you under the Apache License, version 2.0
    5    * (the "License"); you may not use this file except in compliance with the
    6    * License.  You may obtain a copy of the License at:
    7    *
    8    *    http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
    12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
    13   * License for the specific language governing permissions and limitations
    14   * under the License.
    15   */
    16  package org.jboss.netty.channel;
    17
    18  import java.util.EventListener;
    19
    20  /**
    21   * Listens to the result of a {@link ChannelFuture}.  The result of the
    22   * asynchronous {@link Channel} I/O operation is notified once this listener
    23   * is added by calling {@link ChannelFuture#addListener(ChannelFutureListener)}.
    24   *
    25   * <h3>Return the control to the caller quickly</h3>
    26   *
    27   * {@link #operationComplete(ChannelFuture)} is directly called by an I/O
    28   * thread.  Therefore, performing a time consuming task or a blocking operation
    29   * in the handler method can cause an unexpected pause during I/O.  If you need
    30   * to perform a blocking operation on I/O completion, try to execute the
    31   * operation in a different thread using a thread pool.
    32   *
    33   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
    34   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
    35   *
    36   * @version $Rev: 2185 $, $Date: 2010-02-19 14:13:48 +0900 (Fri, 19 Feb 2010) $
    37   */
    38  public interface ChannelFutureListener extends EventListener {
    39
    40      /**
    41       * A {@link ChannelFutureListener} that closes the {@link Channel} which is
    42       * associated with the specified {@link ChannelFuture}.
    43       */
    44      static ChannelFutureListener CLOSE = new ChannelFutureListener() {
    45          public void operationComplete(ChannelFuture future) {
    46              future.getChannel().close();
    47          }
    48      };
    49
    50      /**
    51       * A {@link ChannelFutureListener} that closes the {@link Channel} when the
    52       * operation ended up with a failure or cancellation rather than a success.
    53       */
    54      static ChannelFutureListener CLOSE_ON_FAILURE = new ChannelFutureListener() {
    55          public void operationComplete(ChannelFuture future) {
    56              if (!future.isSuccess()) {
    57                  future.getChannel().close();
    58              }
    59          }
    60      };
    61
    62      /**
    63       * Invoked when the I/O operation associated with the {@link ChannelFuture}
    64       * has been completed.
    65       *
    66       * @param future  the source {@link ChannelFuture} which called this
    67       *                callback
    68       */
    69      void operationComplete(ChannelFuture future) throws Exception;
    70  }