--- jsr166/src/main/java/util/SplittableRandom.java	2013/07/11 23:22:01	1.6
+++ jsr166/src/main/java/util/SplittableRandom.java	2013/07/14 03:47:31	1.9
@@ -35,14 +35,15 @@ import java.util.stream.IntStream;
 import java.util.stream.LongStream;
 import java.util.stream.DoubleStream;
 
-
 /**
  * A generator of uniform pseudorandom values applicable for use in
  * (among other contexts) isolated parallel computations that may
  * generate subtasks. Class SplittableRandom supports methods for
  * producing pseudorandom numbers of type {@code int}, {@code long},
  * and {@code double} with similar usages as for class
- * {@link java.util.Random} but differs in the following ways: <ul>
+ * {@link java.util.Random} but differs in the following ways:
+ *
+ * <ul>
  *
  * <li>Series of generated values pass the DieHarder suite testing
  * independence and uniformity properties of random number generators.
@@ -54,8 +55,8 @@ import java.util.stream.DoubleStream;
  *
  * <li> Method {@link #split} constructs and returns a new
  * SplittableRandom instance that shares no mutable state with the
- * current instance. However, with very high probability, the set of
- * values collectively generated by the two objects has the same
+ * current instance. However, with very high probability, the
+ * values collectively generated by the two objects have the same
  * statistical properties as if the same quantity of values were
  * generated by a single thread using a single {@code
  * SplittableRandom} object.  </li>
@@ -97,11 +98,12 @@ public class SplittableRandom {
      * Random-Number Generation for Dynamic-Multithreading Platforms",
      * PPoPP 2012, but improves and extends it in several ways.
      *
-     * The primary update step is simply to add a constant ("gamma")
-     * to the current seed, modulo a prime ("George"). However, the
-     * nextLong and nextInt methods do not return this value, but
-     * instead the results of bit-mixing transformations that produce
-     * more uniformly distributed sequences.
+     * The primary update step (see method nextSeed()) is simply to
+     * add a constant ("gamma") to the current seed, modulo a prime
+     * ("George"). However, the nextLong and nextInt methods do not
+     * return this value, but instead the results of bit-mixing
+     * transformations that produce more uniformly distributed
+     * sequences.
      *
      * "George" is the otherwise nameless (because it cannot be
      * represented) prime number 2^64+13. Using a prime number larger
@@ -179,7 +181,7 @@ public class SplittableRandom {
 
     /**
      * The least non-zero value returned by nextDouble(). This value
-     * is scaled by a random value of 52 bits to produce a result.
+     * is scaled by a random value of 53 bits to produce a result.
      */
     private static final double DOUBLE_UNIT = 1.0 / (1L << 53);
 
@@ -206,23 +208,6 @@ public class SplittableRandom {
     private final long nextSplit;
 
     /**
-     * Internal constructor used by all other constructors and by
-     * method split. Establishes the initial seed for this instance,
-     * and uses the given splitSeed to establish gamma, as well as the
-     * nextSplit to use by this instance.
-     */
-    private SplittableRandom(long seed, long splitSeed) {
-        this.seed = seed;
-        long s = splitSeed, g;
-        do { // ensure gamma >= 13, considered as an unsigned integer
-            s = addGammaModGeorge(s, GAMMA_GAMMA);
-            g = mix64(s);
-        } while (Long.compareUnsigned(g, 13L) < 0);
-        this.gamma = g;
-        this.nextSplit = s;
-    }
-
-    /**
      * Adds the given gamma value, g, to the given seed value s, mod
      * George (2^64+13). We regard s and g as unsigned values
      * (ranging from 0 to 2^64-1). We add g to s either once or twice
@@ -244,14 +229,6 @@ public class SplittableRandom {
     }
 
     /**
-     * Updates in-place and returns seed.
-     * See above for explanation.
-     */
-    private long nextSeed() {
-        return seed = addGammaModGeorge(seed, gamma);
-    }
-
-    /**
      * Returns a bit-mixed transformation of its argument.
      * See above for explanation.
      */
@@ -275,7 +252,33 @@ public class SplittableRandom {
     }
 
     /**
-     * Atomically updates and returns next seed for default constructor
+     * Internal constructor used by all other constructors and by
+     * method split. Establishes the initial seed for this instance,
+     * and uses the given splitSeed to establish gamma, as well as the
+     * nextSplit to use by this instance. The loop to skip ineligible
+     * gammas very rarely iterates, and does so at most 13 times.
+     */
+    private SplittableRandom(long seed, long splitSeed) {
+        this.seed = seed;
+        long s = splitSeed, g;
+        do { // ensure gamma >= 13, considered as an unsigned integer
+            s = addGammaModGeorge(s, GAMMA_GAMMA);
+            g = mix64(s);
+        } while (Long.compareUnsigned(g, 13L) < 0);
+        this.gamma = g;
+        this.nextSplit = s;
+    }
+
+    /**
+     * Updates in-place and returns seed.
+     * See above for explanation.
+     */
+    private long nextSeed() {
+        return seed = addGammaModGeorge(seed, gamma);
+    }
+
+    /**
+     * Atomically updates and returns next seed for default constructor.
      */
     private static long nextDefaultSeed() {
         long oldSeed, newSeed;
@@ -332,16 +335,16 @@ public class SplittableRandom {
         long r = mix64(nextSeed());
         if (origin < bound) {
             long n = bound - origin, m = n - 1;
-            if ((n & m) == 0L) // power of two
+            if ((n & m) == 0L)  // power of two
                 r = (r & m) + origin;
-            else if (n > 0) { // reject over-represented candidates
+            else if (n > 0L) {  // reject over-represented candidates
                 for (long u = r >>> 1;            // ensure nonnegative
-                     u + m - (r = u % n) < 0L;    // reject
+                     u + m - (r = u % n) < 0L;    // rejection check
                      u = mix64(nextSeed()) >>> 1) // retry
                     ;
                 r += origin;
             }
-            else {             // range not representable as long
+            else {              // range not representable as long
                 while (r < origin || r >= bound)
                     r = mix64(nextSeed());
             }
@@ -365,7 +368,7 @@ public class SplittableRandom {
                 r = (r & m) + origin;
             else if (n > 0) {
                 for (int u = r >>> 1;
-                     u + m - (r = u % n) < 0L;
+                     u + m - (r = u % n) < 0;
                      u = mix32(nextSeed()) >>> 1)
                     ;
                 r += origin;
@@ -389,7 +392,7 @@ public class SplittableRandom {
         double r = (nextLong() >>> 11) * DOUBLE_UNIT;
         if (origin < bound) {
             r = r * (bound - origin) + origin;
-            if (r == bound) // correct for rounding
+            if (r >= bound) // correct for rounding
                 r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
         }
         return r;
@@ -398,9 +401,9 @@ public class SplittableRandom {
     /* ---------------- public methods ---------------- */
 
     /**
-     * Creates a new SplittableRandom instance using the given initial
-     * seed. Two SplittableRandom instances created with the same seed
-     * generate identical sequences of values.
+     * Creates a new SplittableRandom instance using the specified
+     * initial seed. SplittableRandom instances created with the same
+     * seed generate identical sequences of values.
      *
      * @param seed the initial seed
      */
@@ -439,21 +442,21 @@ public class SplittableRandom {
     /**
      * Returns a pseudorandom {@code int} value.
      *
-     * @return a pseudorandom value
+     * @return a pseudorandom {@code int} value
      */
     public int nextInt() {
         return mix32(nextSeed());
     }
 
     /**
-     * Returns a pseudorandom {@code int} value between 0 (inclusive)
+     * Returns a pseudorandom {@code int} value between zero (inclusive)
      * and the specified bound (exclusive).
      *
      * @param bound the bound on the random number to be returned.  Must be
      *        positive.
-     * @return a pseudorandom {@code int} value between {@code 0}
+     * @return a pseudorandom {@code int} value between zero
      *         (inclusive) and the bound (exclusive).
-     * @exception IllegalArgumentException if the bound is not positive
+     * @throws IllegalArgumentException if the bound is less than zero
      */
     public int nextInt(int bound) {
         if (bound <= 0)
@@ -465,7 +468,7 @@ public class SplittableRandom {
             r &= m;
         else { // reject over-represented candidates
             for (int u = r >>> 1;
-                 u + m - (r = u % bound) < 0L;
+                 u + m - (r = u % bound) < 0;
                  u = mix32(nextSeed()) >>> 1)
                 ;
         }
@@ -480,7 +483,7 @@ public class SplittableRandom {
      * @param bound the upper bound (exclusive)
      * @return a pseudorandom {@code int} value between the origin
      *         (inclusive) and the bound (exclusive).
-     * @exception IllegalArgumentException if {@code origin} is greater than
+     * @throws IllegalArgumentException if {@code origin} is greater than
      *         or equal to {@code bound}
      */
     public int nextInt(int origin, int bound) {
@@ -492,21 +495,21 @@ public class SplittableRandom {
     /**
      * Returns a pseudorandom {@code long} value.
      *
-     * @return a pseudorandom value
+     * @return a pseudorandom {@code long} value
      */
     public long nextLong() {
         return mix64(nextSeed());
     }
 
     /**
-     * Returns a pseudorandom {@code long} value between 0 (inclusive)
+     * Returns a pseudorandom {@code long} value between zero (inclusive)
      * and the specified bound (exclusive).
      *
      * @param bound the bound on the random number to be returned.  Must be
      *        positive.
-     * @return a pseudorandom {@code long} value between {@code 0}
+     * @return a pseudorandom {@code long} value between zero
      *         (inclusive) and the bound (exclusive).
-     * @exception IllegalArgumentException if the bound is not positive
+     * @throws IllegalArgumentException if {@code bound} is less than zero
      */
     public long nextLong(long bound) {
         if (bound <= 0)
@@ -533,7 +536,7 @@ public class SplittableRandom {
      * @param bound the upper bound (exclusive)
      * @return a pseudorandom {@code long} value between the origin
      *         (inclusive) and the bound (exclusive).
-     * @exception IllegalArgumentException if {@code origin} is greater than
+     * @throws IllegalArgumentException if {@code origin} is greater than
      *         or equal to {@code bound}
      */
     public long nextLong(long origin, long bound) {
@@ -543,11 +546,11 @@ public class SplittableRandom {
     }
 
     /**
-     * Returns a pseudorandom {@code double} value between {@code 0.0}
-     * (inclusive) and {@code 1.0} (exclusive).
+     * Returns a pseudorandom {@code double} value between zero
+     * (inclusive) and one (exclusive).
      *
-     * @return a pseudorandom value between {@code 0.0}
-     * (inclusive) and {@code 1.0} (exclusive)
+     * @return a pseudorandom {@code double} value between zero
+     * (inclusive) and one (exclusive)
      */
     public double nextDouble() {
         return (nextLong() >>> 11) * DOUBLE_UNIT;
@@ -559,12 +562,12 @@ public class SplittableRandom {
      *
      * @param bound the bound on the random number to be returned.  Must be
      *        positive.
-     * @return a pseudorandom {@code double} value between {@code 0.0}
+     * @return a pseudorandom {@code double} value between zero
      *         (inclusive) and the bound (exclusive).
-     * @throws IllegalArgumentException if {@code bound} is not positive
+     * @throws IllegalArgumentException if {@code bound} is less than zero
      */
     public double nextDouble(double bound) {
-        if (bound <= 0.0)
+        if (!(bound > 0.0))
             throw new IllegalArgumentException("bound must be positive");
         double result = nextDouble() * bound;
         return (result < bound) ?  result : // correct for rounding
@@ -572,7 +575,7 @@ public class SplittableRandom {
     }
 
     /**
-     * Returns a pseudorandom {@code double} value between the given
+     * Returns a pseudorandom {@code double} value between the specified
      * origin (inclusive) and bound (exclusive).
      *
      * @param origin the least value returned
@@ -583,7 +586,7 @@ public class SplittableRandom {
      *         or equal to {@code bound}
      */
     public double nextDouble(double origin, double bound) {
-        if (origin >= bound)
+        if (!(origin < bound))
             throw new IllegalArgumentException("bound must be greater than origin");
         return internalNextDouble(origin, bound);
     }
@@ -592,13 +595,13 @@ public class SplittableRandom {
     // maintenance purposes the small differences across forms.
 
     /**
-     * Returns a stream with the given {@code streamSize} number of
+     * Returns a stream producing the given {@code streamSize} number of
      * pseudorandom {@code int} values.
      *
      * @param streamSize the number of values to generate
      * @return a stream of pseudorandom {@code int} values
      * @throws IllegalArgumentException if {@code streamSize} is
-     * less than zero
+     *         less than zero
      */
     public IntStream ints(long streamSize) {
         if (streamSize < 0L)
@@ -626,7 +629,7 @@ public class SplittableRandom {
     }
 
     /**
-     * Returns a stream with the given {@code streamSize} number of
+     * Returns a stream producing the given {@code streamSize} number of
      * pseudorandom {@code int} values, each conforming to the given
      * origin and bound.
      *
@@ -634,10 +637,9 @@ public class SplittableRandom {
      * @param randomNumberOrigin the origin of each random value
      * @param randomNumberBound the bound of each random value
      * @return a stream of pseudorandom {@code int} values,
-     * each with the given origin and bound.
+     *         each with the given origin and bound.
      * @throws IllegalArgumentException if {@code streamSize} is
-     * less than zero.
-     * @throws IllegalArgumentException if {@code randomNumberOrigin}
+     *         less than zero, or {@code randomNumberOrigin}
      *         is greater than or equal to {@code randomNumberBound}
      */
     public IntStream ints(long streamSize, int randomNumberOrigin,
@@ -662,7 +664,7 @@ public class SplittableRandom {
      * @param randomNumberOrigin the origin of each random value
      * @param randomNumberBound the bound of each random value
      * @return a stream of pseudorandom {@code int} values,
-     * each with the given origin and bound.
+     *         each with the given origin and bound.
      * @throws IllegalArgumentException if {@code randomNumberOrigin}
      *         is greater than or equal to {@code randomNumberBound}
      */
@@ -676,13 +678,13 @@ public class SplittableRandom {
     }
 
     /**
-     * Returns a stream with the given {@code streamSize} number of
+     * Returns a stream producing the given {@code streamSize} number of
      * pseudorandom {@code long} values.
      *
      * @param streamSize the number of values to generate
-     * @return a stream of {@code long} values
+     * @return a stream of pseudorandom {@code long} values
      * @throws IllegalArgumentException if {@code streamSize} is
-     * less than zero
+     *         less than zero
      */
     public LongStream longs(long streamSize) {
         if (streamSize < 0L)
@@ -710,7 +712,7 @@ public class SplittableRandom {
     }
 
     /**
-     * Returns a stream with the given {@code streamSize} number of
+     * Returns a stream producing the given {@code streamSize} number of
      * pseudorandom {@code long} values, each conforming to the
      * given origin and bound.
      *
@@ -718,10 +720,9 @@ public class SplittableRandom {
      * @param randomNumberOrigin the origin of each random value
      * @param randomNumberBound the bound of each random value
      * @return a stream of pseudorandom {@code long} values,
-     * each with the given origin and bound.
+     *         each with the given origin and bound.
      * @throws IllegalArgumentException if {@code streamSize} is
-     * less than zero.
-     * @throws IllegalArgumentException if {@code randomNumberOrigin}
+     *         less than zero, or {@code randomNumberOrigin}
      *         is greater than or equal to {@code randomNumberBound}
      */
     public LongStream longs(long streamSize, long randomNumberOrigin,
@@ -746,7 +747,7 @@ public class SplittableRandom {
      * @param randomNumberOrigin the origin of each random value
      * @param randomNumberBound the bound of each random value
      * @return a stream of pseudorandom {@code long} values,
-     * each with the given origin and bound.
+     *         each with the given origin and bound.
      * @throws IllegalArgumentException if {@code randomNumberOrigin}
      *         is greater than or equal to {@code randomNumberBound}
      */
@@ -760,14 +761,14 @@ public class SplittableRandom {
     }
 
     /**
-     * Returns a stream with the given {@code streamSize} number of
-     * pseudorandom {@code double} values, each between {@code 0.0}
-     * (inclusive) and {@code 1.0} (exclusive).
+     * Returns a stream producing the given {@code streamSize} number of
+     * pseudorandom {@code double} values, each between zero
+     * (inclusive) and one (exclusive).
      *
      * @param streamSize the number of values to generate
      * @return a stream of {@code double} values
      * @throws IllegalArgumentException if {@code streamSize} is
-     * less than zero
+     *         less than zero
      */
     public DoubleStream doubles(long streamSize) {
         if (streamSize < 0L)
@@ -780,8 +781,8 @@ public class SplittableRandom {
 
     /**
      * Returns an effectively unlimited stream of pseudorandom {@code
-     * double} values, each between {@code 0.0} (inclusive) and {@code
-     * 1.0} (exclusive).
+     * double} values, each between zero (inclusive) and one
+     * (exclusive).
      *
      * @implNote This method is implemented to be equivalent to {@code
      * doubles(Long.MAX_VALUE)}.
@@ -796,7 +797,7 @@ public class SplittableRandom {
     }
 
     /**
-     * Returns a stream with the given {@code streamSize} number of
+     * Returns a stream producing the given {@code streamSize} number of
      * pseudorandom {@code double} values, each conforming to the
      * given origin and bound.
      *
@@ -814,7 +815,7 @@ public class SplittableRandom {
                                 double randomNumberBound) {
         if (streamSize < 0L)
             throw new IllegalArgumentException("negative Stream size");
-        if (randomNumberOrigin >= randomNumberBound)
+        if (!(randomNumberOrigin < randomNumberBound))
             throw new IllegalArgumentException("bound must be greater than origin");
         return StreamSupport.doubleStream
             (new RandomDoublesSpliterator
@@ -837,7 +838,7 @@ public class SplittableRandom {
      *         is greater than or equal to {@code randomNumberBound}
      */
     public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
-        if (randomNumberOrigin >= randomNumberBound)
+        if (!(randomNumberOrigin < randomNumberBound))
             throw new IllegalArgumentException("bound must be greater than origin");
         return StreamSupport.doubleStream
             (new RandomDoublesSpliterator
@@ -847,7 +848,7 @@ public class SplittableRandom {
 
     /**
      * Spliterator for int streams.  We multiplex the four int
-     * versions into one class by treating and bound < origin as
+     * versions into one class by treating a bound less than origin as
      * unbounded, and also by treating "infinite" as equivalent to
      * Long.MAX_VALUE. For splits, it uses the standard divide-by-two
      * approach. The long and double versions of this class are
@@ -1014,4 +1015,3 @@ public class SplittableRandom {
     }
 
 }
-