| /* FileLock.java -- |
| Copyright (C) 2002, 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 java.nio.channels; |
| |
| import java.io.IOException; |
| |
| |
| /** |
| * @since 1.4 |
| */ |
| public abstract class FileLock |
| { |
| private final FileChannel channel; |
| private final long position; |
| private final long size; |
| private final boolean shared; |
| |
| /** |
| * Initializes the file lock. |
| * |
| * @exception IllegalArgumentException If the preconditions on the parameters do not hold |
| */ |
| protected FileLock(FileChannel channel, long position, long size, |
| boolean shared) |
| { |
| if (position < 0 || size < 0) |
| throw new IllegalArgumentException(); |
| |
| this.channel = channel; |
| this.position = position; |
| this.size = size; |
| this.shared = shared; |
| } |
| |
| /** |
| * Tells whether or not this lock is valid. |
| */ |
| public abstract boolean isValid(); |
| |
| /** |
| * Releases this lock. |
| * |
| * @exception IOException If an error occurs |
| * @exception ClosedChannelException If the locked channel is no longer open. |
| */ |
| public abstract void release() throws IOException; |
| |
| /** |
| * Returns the file channel upon whose file this lock is held. |
| */ |
| public final FileChannel channel() |
| { |
| return channel; |
| } |
| |
| /** |
| * Tells whether this lock is shared. |
| */ |
| public final boolean isShared() |
| { |
| return shared; |
| } |
| |
| /** |
| * Tells whether or not this lock overlaps the given lock range. |
| */ |
| public final boolean overlaps(long position, long size) |
| { |
| if (position > this.position + this.size) |
| return false; |
| |
| if (position + size < this.position) |
| return false; |
| |
| return true; |
| } |
| |
| /** |
| * Returns the position within the file of the first byte of the |
| * locked region. |
| */ |
| public final long position() |
| { |
| return position; |
| } |
| |
| /** |
| * Returns the size of the locked region in bytes. |
| */ |
| public final long size() |
| { |
| return size; |
| } |
| |
| /** |
| * Returns a string describing the range, type, and validity of this lock. |
| */ |
| public final String toString() |
| { |
| StringBuffer buf = new StringBuffer(getClass().getName()); |
| buf.append("["); |
| buf.append(position); |
| buf.append(":"); |
| buf.append(size); |
| if (shared) |
| buf.append(" shared"); |
| else |
| buf.append(" exclusive"); |
| if (isValid()) |
| buf.append(" valid]"); |
| else |
| buf.append(" invalid]"); |
| return buf.toString(); |
| } |
| } |