151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski/* 246805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved. 351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This code is free software; you can redistribute it and/or modify it 651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * under the terms of the GNU General Public License version 2 only, as 751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * published by the Free Software Foundation. Oracle designates this 851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * particular file as subject to the "Classpath" exception as provided 951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * by Oracle in the LICENSE file that accompanied this code. 1051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 1151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This code is distributed in the hope that it will be useful, but WITHOUT 1251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 1351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 1451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * version 2 for more details (a copy is included in the LICENSE file that 1551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * accompanied this code). 1651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 1751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * You should have received a copy of the GNU General Public License version 1851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 2 along with this work; if not, write to the Free Software Foundation, 1951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 2051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 2151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 2251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * or visit www.oracle.com if you need additional information or have any 2351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * questions. 2451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 2551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 2651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskipackage java.nio.channels; 2751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 2851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskiimport java.io.IOException; 2951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 3051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski/** 3151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * A token representing a lock on a region of a file. 3251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 3351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A file-lock object is created each time a lock is acquired on a file via 3451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * one of the {@link FileChannel#lock(long,long,boolean) lock} or {@link 3551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * FileChannel#tryLock(long,long,boolean) tryLock} methods of the 36e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * {@link FileChannel} class, or the {@link 37e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * AsynchronousFileChannel#lock(long,long,boolean,Object,CompletionHandler) lock} 38e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * or {@link AsynchronousFileChannel#tryLock(long,long,boolean) tryLock} 39e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * methods of the {@link AsynchronousFileChannel} class. 4051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 4151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A file-lock object is initially valid. It remains valid until the lock 4251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is released by invoking the {@link #release release} method, by closing the 4351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * channel that was used to acquire it, or by the termination of the Java 4451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * virtual machine, whichever comes first. The validity of a lock may be 4551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * tested by invoking its {@link #isValid isValid} method. 4651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 4751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A file lock is either <i>exclusive</i> or <i>shared</i>. A shared lock 4851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * prevents other concurrently-running programs from acquiring an overlapping 4951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * exclusive lock, but does allow them to acquire overlapping shared locks. An 5051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * exclusive lock prevents other programs from acquiring an overlapping lock of 5151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * either type. Once it is released, a lock has no further effect on the locks 5251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * that may be acquired by other programs. 5351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 5451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Whether a lock is exclusive or shared may be determined by invoking its 5551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@link #isShared isShared} method. Some platforms do not support shared 5651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * locks, in which case a request for a shared lock is automatically converted 5751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * into a request for an exclusive lock. 5851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 5951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> The locks held on a particular file by a single Java virtual machine do 6051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * not overlap. The {@link #overlaps overlaps} method may be used to test 6151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * whether a candidate lock range overlaps an existing lock. 6251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 6351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A file-lock object records the file channel upon whose file the lock is 6451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * held, the type and validity of the lock, and the position and size of the 6551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * locked region. Only the validity of a lock is subject to change over time; 6651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * all other aspects of a lock's state are immutable. 6751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 6851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> File locks are held on behalf of the entire Java virtual machine. 6951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * They are not suitable for controlling access to a file by multiple 7051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * threads within the same virtual machine. 7151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 7251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> File-lock objects are safe for use by multiple concurrent threads. 7351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 7451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 7546805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * <a name="pdep"></a><h2> Platform dependencies </h2> 7651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 7751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> This file-locking API is intended to map directly to the native locking 7851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * facility of the underlying operating system. Thus the locks held on a file 7951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * should be visible to all programs that have access to the file, regardless 8051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * of the language in which those programs are written. 8151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 8251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Whether or not a lock actually prevents another program from accessing 8351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * the content of the locked region is system-dependent and therefore 8451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * unspecified. The native file-locking facilities of some systems are merely 8551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <i>advisory</i>, meaning that programs must cooperatively observe a known 8651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * locking protocol in order to guarantee data integrity. On other systems 8751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * native file locks are <i>mandatory</i>, meaning that if one program locks a 8851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * region of a file then other programs are actually prevented from accessing 8951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * that region in a way that would violate the lock. On yet other systems, 9051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * whether native file locks are advisory or mandatory is configurable on a 9151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * per-file basis. To ensure consistent and correct behavior across platforms, 9251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * it is strongly recommended that the locks provided by this API be used as if 9351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * they were advisory locks. 9451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 9551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> On some systems, acquiring a mandatory lock on a region of a file 9651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * prevents that region from being {@link java.nio.channels.FileChannel#map 9751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <i>mapped into memory</i>}, and vice versa. Programs that combine 9851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * locking and mapping should be prepared for this combination to fail. 9951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 10051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> On some systems, closing a channel releases all locks held by the Java 10151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * virtual machine on the underlying file regardless of whether the locks were 10251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * acquired via that channel or via another channel open on the same file. It 10351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is strongly recommended that, within a program, a unique channel be used to 10451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * acquire all locks on any given file. 10551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 10651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Some network filesystems permit file locking to be used with 10751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * memory-mapped files only when the locked regions are page-aligned and a 10851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * whole multiple of the underlying hardware's page size. Some network 10951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * filesystems do not implement file locks on regions that extend past a 11051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * certain position, often 2<sup>30</sup> or 2<sup>31</sup>. In general, great 11151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * care should be taken when locking files that reside on network filesystems. 11251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 11351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 11451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @author Mark Reinhold 11551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @author JSR-51 Expert Group 11651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @since 1.4 11751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 11851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 11951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskipublic abstract class FileLock implements AutoCloseable { 12051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 12151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private final Channel channel; 12251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private final long position; 12351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private final long size; 12451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private final boolean shared; 12551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 12651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 12746805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * Initializes a new instance of this class. 12851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 12951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param channel 13051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * The file channel upon whose file this lock is held 13151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 13251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param position 13351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * The position within the file at which the locked region starts; 13451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * must be non-negative 13551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 13651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param size 13751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * The size of the locked region; must be non-negative, and the sum 13851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <tt>position</tt> + <tt>size</tt> must be non-negative 13951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 14051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param shared 14151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <tt>true</tt> if this lock is shared, 14251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <tt>false</tt> if it is exclusive 14351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 14451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalArgumentException 14551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If the preconditions on the parameters do not hold 14651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 14751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski protected FileLock(FileChannel channel, 14851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski long position, long size, boolean shared) 14951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski { 15051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (position < 0) 15151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Negative position"); 15251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (size < 0) 15351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Negative size"); 154e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera if (position + size < 0) 155e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera throw new IllegalArgumentException("Negative position + size"); 156e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera this.channel = channel; 157e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera this.position = position; 158e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera this.size = size; 159e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera this.shared = shared; 160e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera } 161e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera 162e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera /** 163e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * Initializes a new instance of this class. 164e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * 165e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * @param channel 166e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * The channel upon whose file this lock is held 167e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * 168e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * @param position 169e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * The position within the file at which the locked region starts; 170e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * must be non-negative 171e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * 172e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * @param size 173e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * The size of the locked region; must be non-negative, and the sum 174e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * <tt>position</tt> + <tt>size</tt> must be non-negative 175e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * 176e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * @param shared 177e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * <tt>true</tt> if this lock is shared, 178e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * <tt>false</tt> if it is exclusive 179e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * 180e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * @throws IllegalArgumentException 181e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * If the preconditions on the parameters do not hold 182e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * 183e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera * @since 1.7 184e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera */ 185e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera protected FileLock(AsynchronousFileChannel channel, 186e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera long position, long size, boolean shared) 187e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera { 188e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera if (position < 0) 189e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera throw new IllegalArgumentException("Negative position"); 190e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera if (size < 0) 191e6bac4bf9c85c2454ce22c91da6c654552c268e0Shubham Ajmera throw new IllegalArgumentException("Negative size"); 19251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (position + size < 0) 19351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Negative position + size"); 19451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski this.channel = channel; 19551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski this.position = position; 19651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski this.size = size; 19751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski this.shared = shared; 19851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 19951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 20051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 20151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns the file channel upon whose file this lock was acquired. 20251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 20351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> This method has been superseded by the {@link #acquiredBy acquiredBy} 20451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * method. 20551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 20651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return The file channel, or {@code null} if the file lock was not 20751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * acquired by a file channel. 20851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 20951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public final FileChannel channel() { 21051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return (channel instanceof FileChannel) ? (FileChannel)channel : null; 21151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 21251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 21351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 21451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns the channel upon whose file this lock was acquired. 21551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 21651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return The channel upon whose file this lock was acquired. 21751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 21851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @since 1.7 21951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 22051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public Channel acquiredBy() { 22151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return channel; 22251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 22351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 22451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 22551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns the position within the file of the first byte of the locked 22651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * region. 22751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 22851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A locked region need not be contained within, or even overlap, the 22951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * actual underlying file, so the value returned by this method may exceed 23051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * the file's current size. </p> 23151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 23251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return The position 23351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 23451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public final long position() { 23551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return position; 23651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 23751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 23851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 23951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns the size of the locked region in bytes. 24051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 24151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A locked region need not be contained within, or even overlap, the 24251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * actual underlying file, so the value returned by this method may exceed 24351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * the file's current size. </p> 24451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 24551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return The size of the locked region 24651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 24751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public final long size() { 24851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return size; 24951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 25051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 25151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 25246805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * Tells whether this lock is shared. 25351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 25451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return <tt>true</tt> if lock is shared, 25551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <tt>false</tt> if it is exclusive 25651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 25751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public final boolean isShared() { 25851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return shared; 25951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 26051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 26151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 26246805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * Tells whether or not this lock overlaps the given lock range. 26346805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * 26446805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * @param position 26546805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * The starting position of the lock range 26646805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * @param size 26746805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * The size of the lock range 26851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 26951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return <tt>true</tt> if, and only if, this lock and the given lock 27051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * range overlap by at least one byte 27151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 27251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public final boolean overlaps(long position, long size) { 27351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (position + size <= this.position) 27451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return false; // That is below this 27551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (this.position + this.size <= position) 27651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return false; // This is below that 27751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return true; 27851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 27951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 28051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 28151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Tells whether or not this lock is valid. 28251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 28351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A lock object remains valid until it is released or the associated 28451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * file channel is closed, whichever comes first. </p> 28551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 28651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return <tt>true</tt> if, and only if, this lock is valid 28751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 28851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract boolean isValid(); 28951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 29051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 29151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Releases this lock. 29251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 29351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> If this lock object is valid then invoking this method releases the 29451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * lock and renders the object invalid. If this lock object is invalid 29551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * then invoking this method has no effect. </p> 29651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 29751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws ClosedChannelException 29851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If the channel that was used to acquire this lock 29951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is no longer open 30051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 30151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IOException 30251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If an I/O error occurs 30351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 30451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract void release() throws IOException; 30551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 30651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 30751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This method invokes the {@link #release} method. It was added 30851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * to the class so that it could be used in conjunction with the 30951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * automatic resource management block construct. 31051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 31151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @since 1.7 31251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 31351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public final void close() throws IOException { 31451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski release(); 31551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 31651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 31751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 31851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns a string describing the range, type, and validity of this lock. 31951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 32051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return A descriptive string 32151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 32251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public final String toString() { 32351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return (this.getClass().getName() 32451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski + "[" + position 32551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski + ":" + size 32651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski + " " + (shared ? "shared" : "exclusive") 32751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski + " " + (isValid() ? "valid" : "invalid") 32851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski + "]"); 32951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 33051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 33151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski} 332