001    /* AbstractInterruptibleChannel.java --
002       Copyright (C) 2002, 2004 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    package java.nio.channels.spi;
039    
040    import java.io.IOException;
041    import java.nio.channels.AsynchronousCloseException;
042    import java.nio.channels.Channel;
043    import java.nio.channels.ClosedByInterruptException;
044    import java.nio.channels.InterruptibleChannel;
045    
046    
047    /**
048     * @author Michael Koch
049     * @since 1.4
050     */
051    public 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    }