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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.core.future;
    21
    22  import org.apache.mina.core.session.IoSession;
    23
    24  /**
    25   * An {@link IoFuture} for {@link IoSession#read() asynchronous read requests}.
    26   *
    27   * <h3>Example</h3>
    28   * <pre>
    29   * IoSession session = ...;
    30   * // useReadOperation must be enabled to use read operation.
    31   * session.getConfig().setUseReadOperation(true);
    32   *
    33   * ReadFuture future = session.read();
    34   * // Wait until a message is received.
    35   * future.await();
    36   * try {
    37   *     Object message = future.getMessage();
    38   * } catch (Exception e) {
    39   *     ...
    40   * }
    41   * </pre>
    42   *
    43   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
    44   */
    45  public interface ReadFuture extends IoFuture {
    46
    47      /**
    48       * Returns the received message.  It returns <tt>null</tt> if this
    49       * future is not ready or the associated {@link IoSession} has been closed.
    50       *
    51       * @throws RuntimeException if read or any relevant operation has failed.
    52       */
    53      Object getMessage();
    54
    55      /**
    56       * Returns <tt>true</tt> if a message was received successfully.
    57       */
    58      boolean isRead();
    59
    60      /**
    61       * Returns <tt>true</tt> if the {@link IoSession} associated with this
    62       * future has been closed.
    63       */
    64      boolean isClosed();
    65
    66      /**
    67       * Returns the cause of the read failure if and only if the read
    68       * operation has failed due to an {@link Exception}.  Otherwise,
    69       * <tt>null</tt> is returned.
    70       */
    71      Throwable getException();
    72
    73      /**
    74       * Sets the message is written, and notifies all threads waiting for
    75       * this future.  This method is invoked by MINA internally.  Please do
    76       * not call this method directly.
    77       */
    78      void setRead(Object message);
    79
    80      /**
    81       * Sets the associated {@link IoSession} is closed.  This method is invoked
    82       * by MINA internally.  Please do not call this method directly.
    83       */
    84      void setClosed();
    85
    86      /**
    87       * Sets the cause of the read failure, and notifies all threads waiting
    88       * for this future.  This method is invoked by MINA internally.  Please
    89       * do not call this method directly.
    90       */
    91      void setException(Throwable cause);
    92
    93      ReadFuture await() throws InterruptedException;
    94
    95      ReadFuture awaitUninterruptibly();
    96
    97      ReadFuture addListener(IoFutureListener<?> listener);
    98
    99      ReadFuture removeListener(IoFutureListener<?> listener);
    100 }