1 /*
2  * Copyright (c) 2003, 2015, 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 sun.security.jca;
27 
28 import java.lang.ref.*;
29 
30 import java.security.*;
31 
32 /**
33  * Collection of static utility methods used by the security framework.
34  *
35  * @author  Andreas Sterbenz
36  * @since   1.5
37  */
38 public final class JCAUtil {
39 
JCAUtil()40     private JCAUtil() {
41         // no instantiation
42     }
43 
44     // size of the temporary arrays we use. Should fit into the CPU's 1st
45     // level cache and could be adjusted based on the platform
46     private final static int ARRAY_SIZE = 4096;
47 
48     /**
49      * Get the size of a temporary buffer array to use in order to be
50      * cache efficient. totalSize indicates the total amount of data to
51      * be buffered. Used by the engineUpdate(ByteBuffer) methods.
52      */
getTempArraySize(int totalSize)53     public static int getTempArraySize(int totalSize) {
54         return Math.min(ARRAY_SIZE, totalSize);
55     }
56 
57     // cached SecureRandom instance
58     private static class CachedSecureRandomHolder {
59         public static SecureRandom instance = new SecureRandom();
60     }
61 
62     /**
63      * Get a SecureRandom instance. This method should be used by JDK
64      * internal code in favor of calling "new SecureRandom()". That needs to
65      * iterate through the provider table to find the default SecureRandom
66      * implementation, which is fairly inefficient.
67      */
getSecureRandom()68     public static SecureRandom getSecureRandom() {
69         return CachedSecureRandomHolder.instance;
70     }
71 
72 }
73