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/* FileLockImpl.java -- FileLock associated with a FileChannelImpl.

   Copyright (C) 2002, 2004, 2005 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package gnu.java.nio;

import gnu.java.nio.channels.FileChannelImpl;

import java.io.IOException;

import java.nio.channels.FileLock;

/**

 * A FileLock associated with a FileChannelImpl.

 *

 * @author Michael Koch

 * @since 1.4

 */

public final class FileLockImpl extends FileLock

{

  /**

   * Whether or not this lock is valid, false when channel is closed or

   * release has been explicitly called.

   */

  private boolean valid;

  public FileLockImpl (FileChannelImpl channel, long position,

                       long size, boolean shared)

  {

    super (channel, position, size, shared);

    valid = true;

  }

  /**

   * Releases this lock.

   */

  protected void finalize()

  {

    try

      {

        release();

      }

    catch (IOException e)

      {

        // Ignore this.

      }

  }

  /**

   * Whether or not this lock is valid, false when channel is closed or

   * release has been explicitly called.

   */

  public boolean isValid()

  {

    if (valid)

      valid = channel().isOpen();

    return valid;

  }

  /**

   * Releases the lock if it is still valid. Marks this lock as invalid.

   */

  public void release() throws IOException

  {

    if (isValid())

      {

        valid = false;

        ((FileChannelImpl) channel()).unlock(position(), size());

      }

  }

}