1 //
2 // ========================================================================
3 // Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
4 // ------------------------------------------------------------------------
5 // All rights reserved. This program and the accompanying materials
6 // are made available under the terms of the Eclipse Public License v1.0
7 // and Apache License v2.0 which accompanies this distribution.
8 //
9 // The Eclipse Public License is available at
10 // http://www.eclipse.org/legal/epl-v10.html
11 //
12 // The Apache License v2.0 is available at
13 // http://www.opensource.org/licenses/apache2.0.php
14 //
15 // You may elect to redistribute this code under either of these licenses.
16 // ========================================================================
17 //
18
19 package org.eclipse.jetty.util;
20
21 import java.security.AccessController;
22 import java.security.PrivilegedAction;
23
24 /**
25 * {@link MemoryUtils} provides an abstraction over memory properties and operations.
26 * <p />
27 */
28 public class MemoryUtils
29 {
30 private static final int cacheLineBytes;
31 static
32 {
33 final int defaultValue = 64;
34 int value = defaultValue;
35 try
36 {
37 value = Integer.parseInt(AccessController.doPrivileged(new PrivilegedAction<String>()
38 {
39 @Override
40 public String run()
41 {
42 return System.getProperty("org.eclipse.jetty.util.cacheLineBytes", String.valueOf(defaultValue));
43 }
44 }));
45 }
46 catch (Exception ignored)
47 {
48 }
49 cacheLineBytes = value;
50 }
51
52 private MemoryUtils()
53 {
54 }
55
56 public static int getCacheLineBytes()
57 {
58 return cacheLineBytes;
59 }
60
61 public static int getIntegersPerCacheLine()
62 {
63 return getCacheLineBytes() >> 2;
64 }
65
66 public static int getLongsPerCacheLine()
67 {
68 return getCacheLineBytes() >> 3;
69 }
70
71 }