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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  }