1 /* 2 * Copyright (c) 2003, 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 // lock to use for synchronization 45 private static final Object LOCK = JCAUtil.class; 46 47 // cached SecureRandom instance 48 private static volatile SecureRandom secureRandom; 49 50 // size of the temporary arrays we use. Should fit into the CPU's 1st 51 // level cache and could be adjusted based on the platform 52 private final static int ARRAY_SIZE = 4096; 53 54 /** 55 * Get the size of a temporary buffer array to use in order to be 56 * cache efficient. totalSize indicates the total amount of data to 57 * be buffered. Used by the engineUpdate(ByteBuffer) methods. 58 */ getTempArraySize(int totalSize)59 public static int getTempArraySize(int totalSize) { 60 return Math.min(ARRAY_SIZE, totalSize); 61 } 62 63 /** 64 * Get a SecureRandom instance. This method should me used by JDK 65 * internal code in favor of calling "new SecureRandom()". That needs to 66 * iterate through the provider table to find the default SecureRandom 67 * implementation, which is fairly inefficient. 68 */ getSecureRandom()69 public static SecureRandom getSecureRandom() { 70 // we use double checked locking to minimize synchronization 71 // works because we use a volatile reference 72 SecureRandom r = secureRandom; 73 if (r == null) { 74 synchronized (LOCK) { 75 r = secureRandom; 76 if (r == null) { 77 r = new SecureRandom(); 78 secureRandom = r; 79 } 80 } 81 } 82 return r; 83 } 84 85 } 86