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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
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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 
ExtendedOpenOption(FileSystemOption<Void> option)74     ExtendedOpenOption(FileSystemOption<Void> option) {
75         option.register(this);
76     }
77 }
78