--- jsr166/src/main/java/util/Random.java	2008/05/18 23:59:57	1.22
+++ jsr166/src/main/java/util/Random.java	2011/06/06 19:00:28	1.30
@@ -1,12 +1,12 @@
 /*
- * Copyright 1995-2007 Sun Microsystems, Inc.  All Rights Reserved.
+ * Copyright (c) 1995, 2010, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.  Sun designates this
+ * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
- * by Sun in the LICENSE file that accompanied this code.
+ * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
@@ -18,9 +18,9 @@
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
  */
 
 package java.util;
@@ -32,7 +32,7 @@ import sun.misc.Unsafe;
  * An instance of this class is used to generate a stream of
  * pseudorandom numbers. The class uses a 48-bit seed, which is
  * modified using a linear congruential formula. (See Donald Knuth,
- * <i>The Art of Computer Programming, Volume 3</i>, Section 3.2.1.)
+ * <i>The Art of Computer Programming, Volume 2</i>, Section 3.2.1.)
  * <p>
  * If two instances of {@code Random} are created with the same
  * seed, and the same sequence of method calls is made for each, they
@@ -50,6 +50,18 @@ import sun.misc.Unsafe;
  * <p>
  * Many applications will find the method {@link Math#random} simpler to use.
  *
+ * <p>Instances of {@code java.util.Random} are threadsafe.
+ * However, the concurrent use of the same {@code java.util.Random}
+ * instance across threads may encounter contention and consequent
+ * poor performance. Consider instead using
+ * {@link java.util.concurrent.ThreadLocalRandom} in multithreaded
+ * designs.
+ *
+ * <p>Instances of {@code java.util.Random} are not cryptographically
+ * secure.  Consider instead using {@link java.security.SecureRandom} to
+ * get a cryptographically secure pseudo-random number generator for use
+ * by security-sensitive applications.
+ *
  * @author  Frank Yellin
  * @since   1.0
  */
@@ -65,17 +77,32 @@ class Random implements java.io.Serializ
      */
     private final AtomicLong seed;
 
-    private final static long multiplier = 0x5DEECE66DL;
-    private final static long addend = 0xBL;
-    private final static long mask = (1L << 48) - 1;
+    private static final long multiplier = 0x5DEECE66DL;
+    private static final long addend = 0xBL;
+    private static final long mask = (1L << 48) - 1;
 
     /**
      * Creates a new random number generator. This constructor sets
      * the seed of the random number generator to a value very likely
      * to be distinct from any other invocation of this constructor.
      */
-    public Random() { this(++seedUniquifier + System.nanoTime()); }
-    private static volatile long seedUniquifier = 8682522807148012L;
+    public Random() {
+        this(seedUniquifier() ^ System.nanoTime());
+    }
+
+    private static long seedUniquifier() {
+        // L'Ecuyer, "Tables of Linear Congruential Generators of
+        // Different Sizes and Good Lattice Structure", 1999
+        for (;;) {
+            long current = seedUniquifier.get();
+            long next = current * 181783497276652981L;
+            if (seedUniquifier.compareAndSet(current, next))
+                return next;
+        }
+    }
+
+    private static final AtomicLong seedUniquifier
+        = new AtomicLong(8682522807148012L);
 
     /**
      * Creates a new random number generator using a single {@code long} seed.
@@ -91,8 +118,17 @@ class Random implements java.io.Serializ
      * @see   #setSeed(long)
      */
     public Random(long seed) {
-        this.seed = new AtomicLong(0L);
-        setSeed(seed);
+        if (getClass() == Random.class)
+            this.seed = new AtomicLong(initialScramble(seed));
+        else {
+            // subclass might have overriden setSeed
+            this.seed = new AtomicLong();
+            setSeed(seed);
+        }
+    }
+
+    private static long initialScramble(long seed) {
+        return (seed ^ multiplier) & mask;
     }
 
     /**
@@ -115,8 +151,7 @@ class Random implements java.io.Serializ
      * @param seed the initial seed
      */
     synchronized public void setSeed(long seed) {
-        seed = (seed ^ multiplier) & mask;
-        this.seed.set(seed);
+        this.seed.set(initialScramble(seed));
         haveNextNextGaussian = false;
     }
 
@@ -256,7 +291,7 @@ class Random implements java.io.Serializ
      * @return the next pseudorandom, uniformly distributed {@code int}
      *         value between {@code 0} (inclusive) and {@code n} (exclusive)
      *         from this random number generator's sequence
-     * @exception IllegalArgumentException if n is not positive
+     * @throws IllegalArgumentException if n is not positive
      * @since 1.2
      */
 
@@ -504,7 +539,7 @@ class Random implements java.io.Serializ
 
         // The seed is read in as {@code long} for
         // historical reasons, but it is converted to an AtomicLong.
-        long seedVal = (long) fields.get("seed", -1L);
+        long seedVal = fields.get("seed", -1L);
         if (seedVal < 0)
           throw new java.io.StreamCorruptedException(
                               "Random: invalid seed");