001/* AbstractInterruptibleChannel.java -- 
002   Copyright (C) 2002, 2004 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package java.nio.channels.spi;
039
040import java.io.IOException;
041import java.nio.channels.AsynchronousCloseException;
042import java.nio.channels.Channel;
043import java.nio.channels.ClosedByInterruptException;
044import java.nio.channels.InterruptibleChannel;
045
046
047/**
048 * @author Michael Koch
049 * @since 1.4
050 */
051public abstract class AbstractInterruptibleChannel
052  implements Channel, InterruptibleChannel
053{
054  private boolean closed;
055
056  /**
057   * Initializes the channel.
058   */
059  protected AbstractInterruptibleChannel()
060  {
061  }
062
063  /**
064   * Marks the beginning of an I/O operation that might block indefinitely.
065   */
066  protected final void begin()
067  {
068  }
069
070  /**
071   * Closes the channel.
072   *
073   * @exception IOException If an error occurs
074   */
075  public final void close() throws IOException
076  {
077    if (! closed)
078      {
079        closed = true;
080        implCloseChannel();
081      }
082  }
083
084  /**
085   * Marks the end of an I/O operation that might block indefinitely.
086   *
087   * @param completed true if the task completed successfully,
088   * false otherwise
089   *
090   * @exception AsynchronousCloseException If the channel was asynchronously
091   * closed.
092   * @exception ClosedByInterruptException If the thread blocked in the
093   * I/O operation was interrupted.
094   */
095  protected final void end(boolean completed)
096    throws AsynchronousCloseException
097  {
098    // FIXME: check more here.
099    
100    if (closed) throw new AsynchronousCloseException();
101  }
102
103  /**
104   * Closes the channel.
105   *
106   * @exception IOException If an error occurs
107   */
108  protected abstract void implCloseChannel() throws IOException;
109
110  /**
111   * Tells whether or not this channel is open.
112   * 
113   * @return true if the channel is open, false otherwise 
114   */
115  public final boolean isOpen()
116  {
117    return ! closed;
118  }
119}