Source for gnu.java.nio.FileLockImpl

   1: /* FileLockImpl.java -- FileLock associated with a FileChannelImpl.
   2:    Copyright (C) 2002, 2004, 2005 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package gnu.java.nio;
  40: 
  41: import gnu.java.nio.channels.FileChannelImpl;
  42: 
  43: import java.io.IOException;
  44: import java.nio.channels.FileLock;
  45: 
  46: /**
  47:  * A FileLock associated with a FileChannelImpl.
  48:  *
  49:  * @author Michael Koch
  50:  * @since 1.4
  51:  */
  52: public final class FileLockImpl extends FileLock
  53: {
  54:   /**
  55:    * Whether or not this lock is valid, false when channel is closed or
  56:    * release has been explicitly called.
  57:    */
  58:   private boolean valid;
  59: 
  60:   public FileLockImpl (FileChannelImpl channel, long position,
  61:                        long size, boolean shared)
  62:   {
  63:     super (channel, position, size, shared);
  64:     valid = true;
  65:   }
  66: 
  67:   /**
  68:    * Releases this lock.
  69:    */
  70:   protected void finalize()
  71:   {
  72:     try
  73:       {
  74:     release();
  75:       }
  76:     catch (IOException e)
  77:       {
  78:     // Ignore this.
  79:       }
  80:   }
  81:   
  82:   /**
  83:    * Whether or not this lock is valid, false when channel is closed or
  84:    * release has been explicitly called.
  85:    */
  86:   public boolean isValid()
  87:   {
  88:     if (valid)
  89:       valid = channel().isOpen();
  90:     return valid;
  91:   }
  92: 
  93:   public void close() throws Exception
  94:   {
  95:     release();
  96:   }
  97: 
  98:   /**
  99:    * Releases the lock if it is still valid. Marks this lock as invalid.
 100:    */
 101:   public void release() throws IOException
 102:   {
 103:     if (isValid())
 104:       {
 105:     valid = false;
 106:     ((FileChannelImpl) channel()).unlock(position(), size());
 107:       }
 108:   }
 109: }