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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the 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  
19  /**
20   * Listens to the progress of a time-consuming I/O operation such as a large
21   * file transfer.  If this listener is added to a {@link ChannelFuture} of an
22   * I/O operation that supports progress notification, the listener's
23   * {@link #operationProgressed(ChannelFuture, long, long, long)} method will be
24   * called back by an I/O thread.  If the operation does not support progress
25   * notification, {@link #operationProgressed(ChannelFuture, long, long, long)}
26   * will not be invoked.  Like a usual {@link ChannelFutureListener} that this
27   * interface extends, {@link #operationComplete(ChannelFuture)} will be called
28   * when the future is marked as complete.
29   *
30   * <h3>Return the control to the caller quickly</h3>
31   *
32   * {@link #operationProgressed(ChannelFuture, long, long, long)} and
33   * {@link #operationComplete(ChannelFuture)} is directly called by an I/O
34   * thread.  Therefore, performing a time consuming task or a blocking operation
35   * in the handler method can cause an unexpected pause during I/O.  If you need
36   * to perform a blocking operation on I/O completion, try to execute the
37   * operation in a different thread using a thread pool.
38   */
39  public interface ChannelFutureProgressListener extends ChannelFutureListener {
40  
41      /**
42       * Invoked when the I/O operation associated with the {@link ChannelFuture}
43       * has been progressed.
44       *
45       * @param future  the source {@link ChannelFuture} which called this
46       *                callback
47       */
48      void operationProgressed(ChannelFuture future, long amount, long current, long total) throws Exception;
49  }