1 /*
   2  * Copyright (c) 2007, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.nio.file;
  27 
  28 import java.nio.file.OpenOption;
  29 import jdk.internal.misc.FileSystemOption;
  30 
  31 /**
  32  * Defines <em>extended</em> open options supported on some platforms
  33  * by Sun's provider implementation.
  34  *
  35  * @since 1.7
  36  */
  37 
  38 public enum ExtendedOpenOption implements OpenOption {
  39     /**
  40      * Prevent operations on the file that request read access.
  41      */
  42     NOSHARE_READ(FileSystemOption.NOSHARE_READ),
  43     /**
  44      * Prevent operations on the file that request write access.
  45      */
  46     NOSHARE_WRITE(FileSystemOption.NOSHARE_WRITE),
  47     /**
  48      * Prevent operations on the file that request delete access.
  49      */
  50     NOSHARE_DELETE(FileSystemOption.NOSHARE_DELETE),
  51 
  52     /**
  53      * Requires that direct I/O be used for read or write access.
  54      * Attempting to open a file with this option set will result in
  55      * an {@code UnsupportedOperationException} if the operating system or
  56      * file system does not support Direct I/O or a sufficient equivalent.
  57      *
  58      * @apiNote
  59      * The DIRECT option enables performing file I/O directly between user
  60      * buffers and the file thereby circumventing the operating system page
  61      * cache and possibly avoiding the thrashing which could otherwise occur
  62      * in I/O-intensive applications. This option may be of benefit to
  63      * applications which do their own caching or do random I/O operations
  64      * on large data sets. It is likely to provide the most benefit when
  65      * the file is stored on a device which has high I/O throughput capacity.
  66      * The option should be used with caution however as in general it is
  67      * likely to degrade performance. The performance effects of using it
  68      * should be evaluated in each particular circumstance.
  69      *
  70      * @since 10
  71      */
  72     DIRECT(FileSystemOption.DIRECT);
  73 
  74     ExtendedOpenOption(FileSystemOption<Void> option) {
  75         option.register(this);
  76     }
  77 }