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Comparing jsr166/src/main/java/util/SplittableRandom.java (file contents):
Revision 1.14 by dl, Mon Aug 5 13:58:02 2013 UTC vs.
Revision 1.15 by dl, Fri Aug 9 12:12:10 2013 UTC

# Line 25 | Line 25
25  
26   package java.util;
27  
28 < import java.security.SecureRandom;
28 > import java.net.InetAddress;
29   import java.util.concurrent.atomic.AtomicLong;
30   import java.util.Spliterator;
31   import java.util.function.IntConsumer;
# Line 84 | Line 84 | import java.util.stream.DoubleStream;
84   public class SplittableRandom {
85  
86      /*
87     * File organization: First the non-public methods that constitute
88     * the main algorithm, then the main public methods, followed by
89     * some custom spliterator classes needed for stream methods.
90     *
91     * Credits: Primary algorithm and code by Guy Steele.  Stream
92     * support methods by Doug Lea.  Documentation jointly produced
93     * with additional help from Brian Goetz.
94     */
95
96    /*
87       * Implementation Overview.
88       *
89       * This algorithm was inspired by the "DotMix" algorithm by
90       * Leiserson, Schardl, and Sukha "Deterministic Parallel
91       * Random-Number Generation for Dynamic-Multithreading Platforms",
92 <     * PPoPP 2012, but improves and extends it in several ways.
93 <     *
94 <     * The primary update step (see method nextSeed()) is simply to
95 <     * add a constant ("gamma") to the current seed, modulo a prime
96 <     * ("George"). However, the nextLong and nextInt methods do not
97 <     * return this value, but instead the results of bit-mixing
98 <     * transformations that produce more uniformly distributed
99 <     * sequences.
100 <     *
101 <     * "George" is the otherwise nameless (because it cannot be
102 <     * represented) prime number 2^64+13. Using a prime number larger
103 <     * than can fit in a long ensures that all possible long values
104 <     * can occur, plus 13 others that just get skipped over when they
105 <     * are encountered; see method addGammaModGeorge. For this to
106 <     * work, initial gamma values must be at least 13.
117 <     *
118 <     * The mix64 bit-mixing function called by nextLong and other
119 <     * methods computes the same value as the "64-bit finalizer"
120 <     * function in Austin Appleby's MurmurHash3 algorithm.  See
92 >     * PPoPP 2012, as well as those in "Parallel random numbers: as
93 >     * easy as 1, 2, 3" by Salmon, Morae, Dror, and Shaw, SC 2011.  It
94 >     * differs mainly in simplifying and cheapening operations.
95 >     *
96 >     * The primary update step (method nextSeed()) is to add a
97 >     * constant ("gamma") to the current (64 bit) seed, forming a
98 >     * simple sequence.  The seed and the gamma values for any two
99 >     * SplittableRandom instances are highly likely to be different.
100 >     *
101 >     * Methods nextLong, nextInt, and derivatives do not return the
102 >     * sequence (seed) values, but instead a hash-like bit-mix of
103 >     * their bits, producing more independently distributed sequences.
104 >     * For nextLong, the mix64 bit-mixing function computes the same
105 >     * value as the "64-bit finalizer" function in Austin Appleby's
106 >     * MurmurHash3 algorithm.  See
107       * http://code.google.com/p/smhasher/wiki/MurmurHash3 , which
108       * comments: "The constants for the finalizers were generated by a
109       * simple simulated-annealing algorithm, and both avalanche all
110 <     * bits of 'h' to within 0.25% bias."
111 <     *
112 <     * The value of gamma differs for each instance across a series of
113 <     * splits, and is generated using an independent variant of the
114 <     * same algorithm, but operating across calls to split(), not
115 <     * calls to nextSeed(): Each instance carries the state of this
116 <     * generator as nextSplit. Gammas are treated as 57bit values,
117 <     * advancing by adding GAMMA_GAMMA mod GAMMA_PRIME, and bit-mixed
118 <     * with a 57-bit version of mix, using the "Mix13" multiplicative
119 <     * constants for MurmurHash3 described by David Stafford
120 <     * (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html).
121 <     * The value of GAMMA_GAMMA is arbitrary (except must be at least
122 <     * 13 and less than GAMMA_PRIME), but because it serves as the
123 <     * base of split sequences, should be subject to validation of
124 <     * consequent random number quality metrics.
125 <     *
126 <     * The mix32 function used for nextInt just consists of two of the
127 <     * five lines of mix64; avalanche testing shows that the 64-bit
128 <     * result has its top 32 bits avalanched well, though not the
129 <     * bottom 32 bits.  DieHarder tests show that it is adequate for
130 <     * generating one random int from the 64-bit result of nextSeed.
110 >     * bits of 'h' to within 0.25% bias." The mix32 function is
111 >     * equivalent to (int)(mix64(seed) >>> 32), but faster because it
112 >     * omits a step that doesn't contribute to result.
113 >     *
114 >     * The split operation uses the current generator to form the seed
115 >     * and gamma for another SplittableRandom.  To conservatively
116 >     * avoid potential correlations between seed and value generation,
117 >     * gamma selection (method nextGamma) uses the "Mix13" constants
118 >     * for MurmurHash3 described by David Stafford
119 >     * (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html)
120 >     * To avoid potential weaknesses in bit-mixing transformations, we
121 >     * restrict gammas to odd values with at least 12 and no more than
122 >     * 52 bits set.  Rather than rejecting candidates with too few or
123 >     * too many bits set, method nextGamma flips some bits (which has
124 >     * the effect of mapping at most 4 to any given gamma value).
125 >     * This reduces the effective set of 64bit odd gamma values by
126 >     * about 2<sup>14</sup>, a very tiny percentage, and serves as an
127 >     * automated screening for sequence constant selection that is
128 >     * left as an empirical decision in some other hashing and crypto
129 >     * algorithms.
130 >     *
131 >     * The resulting generator thus transforms a sequence in which
132 >     * (typically) many bits change on each step, with an inexpensive
133 >     * mixer with good (but less than cryptographically secure)
134 >     * avalanching.
135 >     *
136 >     * The default (no-argument) constructor, in essence, invokes
137 >     * split() for a common "seeder" SplittableRandom.  Unlike other
138 >     * cases, this split must be performed in a thread-safe manner, so
139 >     * we use an AtomicLong to represent the seed rather than use an
140 >     * explicit SplittableRandom. To bootstrap the seeder, we start
141 >     * off using a seed based on current time and host. This serves as
142 >     * a slimmed-down (and insecure) variant of SecureRandom that also
143 >     * avoids stalls that may occur when using /dev/random.
144 >     *
145 >     * It is a relatively simple matter to apply the basic design here
146 >     * to use 128 bit seeds. However, emulating 128bit arithmetic and
147 >     * carrying around twice the state add more overhead than appears
148 >     * warranted for current usages.
149       *
150 <     * Support for the default (no-argument) constructor relies on an
151 <     * AtomicLong (defaultSeedGenerator) to help perform the
152 <     * equivalent of a split of a statically constructed
149 <     * SplittableRandom. Unlike other cases, this split must be
150 <     * performed in a thread-safe manner. We use
151 <     * AtomicLong.compareAndSet as the (typically) most efficient
152 <     * mechanism. To bootstrap, we start off using a SecureRandom
153 <     * initial default seed, and update using a fixed
154 <     * DEFAULT_SEED_GAMMA. The default constructor uses GAMMA_GAMMA,
155 <     * not 0, for its splitSeed argument (addGammaModGeorge(0,
156 <     * GAMMA_GAMMA) == GAMMA_GAMMA) to reflect that each is split from
157 <     * this root generator, even though the root is not explicitly
158 <     * represented as a SplittableRandom.
159 <     */
160 <
161 <    /**
162 <     * The prime modulus for gamma values.
163 <     */
164 <    private static final long GAMMA_PRIME = (1L << 57) - 13L;
165 <
166 <    /**
167 <     * The value for producing new gamma values. Must be greater or
168 <     * equal to 13 and less than GAMMA_PRIME. Otherwise, the value is
169 <     * arbitrary subject to validation of the resulting statistical
170 <     * quality of splits.
171 <     */
172 <    private static final long GAMMA_GAMMA = 0x00aae38294f712aabL;
173 <
174 <    /**
175 <     * The seed update value for default constructors.  Must be
176 <     * greater or equal to 13. Otherwise, the value is arbitrary
177 <     * subject to quality checks.
150 >     * File organization: First the non-public methods that constitute
151 >     * the main algorithm, then the main public methods, followed by
152 >     * some custom spliterator classes needed for stream methods.
153       */
179    private static final long DEFAULT_SEED_GAMMA = 0x9e3779b97f4a7c15L;
154  
155      /**
156 <     * The value 13 with 64bit sign bit set. Used in the signed
157 <     * comparison in addGammaModGeorge.
156 >     * The initial gamma value for (unsplit) SplittableRandoms. Must
157 >     * be odd with at least 12 and no more than 52 bits set. Currently
158 >     * set to the golden ratio scaled to 64bits.
159       */
160 <    private static final long BOTTOM13 = 0x800000000000000DL;
160 >    private static final long INITIAL_GAMMA = 0x9e3779b97f4a7c15L;
161  
162      /**
163       * The least non-zero value returned by nextDouble(). This value
# Line 191 | Line 166 | public class SplittableRandom {
166      private static final double DOUBLE_UNIT = 1.0 / (1L << 53);
167  
168      /**
169 <     * The next seed for default constructors.
195 <     */
196 <    private static final AtomicLong defaultSeedGenerator =
197 <        new AtomicLong(getInitialDefaultSeed());
198 <
199 <    /**
200 <     * The seed, updated only via method nextSeed.
169 >     * The seed. Updated only via method nextSeed.
170       */
171      private long seed;
172  
173      /**
174 <     * The constant value added to seed (mod George) on each update.
174 >     * The step value.
175       */
176      private final long gamma;
177  
178      /**
179 <     * The next seed to use for splits. Propagated using
211 <     * addGammaModGeorge across instances.
179 >     * Internal constructor used by all others except default constructor.
180       */
181 <    private final long nextSplit;
182 <
183 <    /**
216 <     * Adds the given gamma value, g, to the given seed value s, mod
217 <     * George (2^64+13). We regard s and g as unsigned values
218 <     * (ranging from 0 to 2^64-1). We add g to s either once or twice
219 <     * (mod George) as necessary to produce an (unsigned) result less
220 <     * than 2^64.  We require that g must be at least 13. This
221 <     * guarantees that if (s+g) mod George >= 2^64 then (s+g+g) mod
222 <     * George < 2^64; thus we need only a conditional, not a loop,
223 <     * to be sure of getting a representable value.
224 <     *
225 <     * Because Java comparison operators are signed, we implement this
226 <     * by conceptually offsetting seed values downwards by 2^63, so
227 <     * 0..13 is represented as Long.MIN_VALUE..BOTTOM13.
228 <     *
229 <     * @param s a seed value, viewed as a signed long
230 <     * @param g a gamma value, 13 <= g (as unsigned)
231 <     */
232 <    private static long addGammaModGeorge(long s, long g) {
233 <        long p = s + g;
234 <        return (p >= s) ? p : ((p >= BOTTOM13) ? p  : p + g) - 13L;
181 >    private SplittableRandom(long seed, long gamma) {
182 >        this.seed = seed;
183 >        this.gamma = gamma;
184      }
185  
186      /**
187 <     * Returns a bit-mixed transformation of its argument.
239 <     * See above for explanation.
187 >     * Computes MurmurHash3 64bit mix function.
188       */
189      private static long mix64(long z) {
190 <        z ^= (z >>> 33);
191 <        z *= 0xff51afd7ed558ccdL;
192 <        z ^= (z >>> 33);
245 <        z *= 0xc4ceb9fe1a85ec53L;
246 <        z ^= (z >>> 33);
247 <        return z;
190 >        z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
191 >        z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
192 >        return z ^ (z >>> 33);
193      }
194  
195      /**
196 <     * Returns a bit-mixed int transformation of its argument.
252 <     * See above for explanation.
196 >     * Returns the 32 high bits of mix64(z) as int.
197       */
198      private static int mix32(long z) {
199 <        z ^= (z >>> 33);
200 <        z *= 0xc4ceb9fe1a85ec53L;
257 <        return (int)(z >>> 32);
199 >        z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
200 >        return (int)(((z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L) >>> 32);
201      }
202  
203      /**
204 <     * Returns a 57-bit mixed transformation of its argument.  See
262 <     * above for explanation.
204 >     * Returns the gamma value to use for a new split instance.
205       */
206 <    private static long mix57(long z) {
207 <        z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L;
266 <        z &= 0x01FFFFFFFFFFFFFFL;
206 >    private static long nextGamma(long z) {
207 >        z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L; // Stafford "Mix13"
208          z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
209 <        z &= 0x01FFFFFFFFFFFFFFL;
210 <        z ^= (z >>> 31);
211 <        return z;
209 >        z = (z ^ (z >>> 31)) | 1L; // force to be odd
210 >        int n = Long.bitCount(z);  // ensure enough 0 and 1 bits
211 >        return (n < 12 || n > 52) ? z ^ 0xaaaaaaaaaaaaaaaaL : z;
212      }
213  
214      /**
215 <     * Internal constructor used by all other constructors and by
275 <     * method split. Establishes the initial seed for this instance,
276 <     * and uses the given splitSeed to establish gamma, as well as the
277 <     * nextSplit to use by this instance. The loop to skip ineligible
278 <     * gammas very rarely iterates, and does so at most 13 times.
279 <     */
280 <    private SplittableRandom(long seed, long splitSeed) {
281 <        this.seed = seed;
282 <        long s = splitSeed, g;
283 <        do { // ensure gamma >= 13, considered as an unsigned integer
284 <            s += GAMMA_GAMMA;
285 <            if (s >= GAMMA_PRIME)
286 <                s -= GAMMA_PRIME;
287 <            g = mix57(s);
288 <        } while (g < 13L);
289 <        this.gamma = g;
290 <        this.nextSplit = s;
291 <    }
292 <
293 <    /**
294 <     * Updates in-place and returns seed.
295 <     * See above for explanation.
215 >     * Adds gamma to seed.
216       */
217      private long nextSeed() {
218 <        return seed = addGammaModGeorge(seed, gamma);
218 >        return seed += gamma;
219      }
220  
221      /**
222 <     * Atomically updates and returns next seed for default constructor.
222 >     * The seed generator for default constructors.
223       */
224 <    private static long nextDefaultSeed() {
225 <        long oldSeed, newSeed;
226 <        do {
227 <            oldSeed = defaultSeedGenerator.get();
308 <            newSeed = addGammaModGeorge(oldSeed, DEFAULT_SEED_GAMMA);
309 <        } while (!defaultSeedGenerator.compareAndSet(oldSeed, newSeed));
310 <        return mix64(newSeed);
311 <    }
224 >    private static final AtomicLong seeder =
225 >        new AtomicLong(mix64((((long)hashedHostAddress()) << 32) ^
226 >                             System.currentTimeMillis()) ^
227 >                       mix64(System.nanoTime()));
228  
229      /**
230 <     * Returns an initial default seed.
230 >     * Returns hash of local host IP address, if available; else 0.
231       */
232 <    private static long getInitialDefaultSeed() {
233 <        byte[] seedBytes = java.security.SecureRandom.getSeed(8);
234 <        long s = (long)(seedBytes[0]) & 0xffL;
235 <        for (int i = 1; i < 8; ++i)
236 <            s = (s << 8) | ((long)(seedBytes[i]) & 0xffL);
237 <        return s;
232 >    private static int hashedHostAddress() {
233 >        try {
234 >            return InetAddress.getLocalHost().hashCode();
235 >        } catch (Exception ex) {
236 >            return 0;
237 >        }
238      }
239  
240 +    // IllegalArgumentException messages
241 +    static final String BadBound = "bound must be positive";
242 +    static final String BadRange = "bound must be greater than origin";
243 +    static final String BadSize  = "size must be non-negative";
244 +
245      /*
246       * Internal versions of nextX methods used by streams, as well as
247       * the public nextX(origin, bound) methods.  These exist mainly to
# Line 440 | Line 361 | public class SplittableRandom {
361       * @param seed the initial seed
362       */
363      public SplittableRandom(long seed) {
364 <        this(seed, 0L);
364 >        this(seed, INITIAL_GAMMA);
365      }
366  
367      /**
# Line 449 | Line 370 | public class SplittableRandom {
370       * of those of any other instances in the current program; and
371       * may, and typically does, vary across program invocations.
372       */
373 <    public SplittableRandom() {
374 <        this(nextDefaultSeed(), GAMMA_GAMMA);
373 >    public SplittableRandom() { // emulate seeder.split()
374 >        this.gamma = nextGamma(this.seed = seeder.addAndGet(INITIAL_GAMMA));
375      }
376  
377      /**
# Line 468 | Line 389 | public class SplittableRandom {
389       * @return the new SplittableRandom instance
390       */
391      public SplittableRandom split() {
392 <        return new SplittableRandom(nextSeed(), nextSplit);
392 >        long s = nextSeed();
393 >        return new SplittableRandom(s, nextGamma(s));
394      }
395  
396      /**
# Line 492 | Line 414 | public class SplittableRandom {
414       */
415      public int nextInt(int bound) {
416          if (bound <= 0)
417 <            throw new IllegalArgumentException("bound must be positive");
417 >            throw new IllegalArgumentException(BadBound);
418          // Specialize internalNextInt for origin 0
419          int r = mix32(nextSeed());
420          int m = bound - 1;
# Line 520 | Line 442 | public class SplittableRandom {
442       */
443      public int nextInt(int origin, int bound) {
444          if (origin >= bound)
445 <            throw new IllegalArgumentException("bound must be greater than origin");
445 >            throw new IllegalArgumentException(BadRange);
446          return internalNextInt(origin, bound);
447      }
448  
# Line 545 | Line 467 | public class SplittableRandom {
467       */
468      public long nextLong(long bound) {
469          if (bound <= 0)
470 <            throw new IllegalArgumentException("bound must be positive");
470 >            throw new IllegalArgumentException(BadBound);
471          // Specialize internalNextLong for origin 0
472          long r = mix64(nextSeed());
473          long m = bound - 1;
# Line 573 | Line 495 | public class SplittableRandom {
495       */
496      public long nextLong(long origin, long bound) {
497          if (origin >= bound)
498 <            throw new IllegalArgumentException("bound must be greater than origin");
498 >            throw new IllegalArgumentException(BadRange);
499          return internalNextLong(origin, bound);
500      }
501  
# Line 600 | Line 522 | public class SplittableRandom {
522       */
523      public double nextDouble(double bound) {
524          if (!(bound > 0.0))
525 <            throw new IllegalArgumentException("bound must be positive");
525 >            throw new IllegalArgumentException(BadBound);
526          double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound;
527          return (result < bound) ?  result : // correct for rounding
528              Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
# Line 619 | Line 541 | public class SplittableRandom {
541       */
542      public double nextDouble(double origin, double bound) {
543          if (!(origin < bound))
544 <            throw new IllegalArgumentException("bound must be greater than origin");
544 >            throw new IllegalArgumentException(BadRange);
545          return internalNextDouble(origin, bound);
546      }
547  
# Line 646 | Line 568 | public class SplittableRandom {
568       */
569      public IntStream ints(long streamSize) {
570          if (streamSize < 0L)
571 <            throw new IllegalArgumentException("negative Stream size");
571 >            throw new IllegalArgumentException(BadSize);
572          return StreamSupport.intStream
573              (new RandomIntsSpliterator
574               (this, 0L, streamSize, Integer.MAX_VALUE, 0),
# Line 686 | Line 608 | public class SplittableRandom {
608      public IntStream ints(long streamSize, int randomNumberOrigin,
609                            int randomNumberBound) {
610          if (streamSize < 0L)
611 <            throw new IllegalArgumentException("negative Stream size");
611 >            throw new IllegalArgumentException(BadSize);
612          if (randomNumberOrigin >= randomNumberBound)
613 <            throw new IllegalArgumentException("bound must be greater than origin");
613 >            throw new IllegalArgumentException(BadRange);
614          return StreamSupport.intStream
615              (new RandomIntsSpliterator
616               (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
# Line 711 | Line 633 | public class SplittableRandom {
633       */
634      public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
635          if (randomNumberOrigin >= randomNumberBound)
636 <            throw new IllegalArgumentException("bound must be greater than origin");
636 >            throw new IllegalArgumentException(BadRange);
637          return StreamSupport.intStream
638              (new RandomIntsSpliterator
639               (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
# Line 729 | Line 651 | public class SplittableRandom {
651       */
652      public LongStream longs(long streamSize) {
653          if (streamSize < 0L)
654 <            throw new IllegalArgumentException("negative Stream size");
654 >            throw new IllegalArgumentException(BadSize);
655          return StreamSupport.longStream
656              (new RandomLongsSpliterator
657               (this, 0L, streamSize, Long.MAX_VALUE, 0L),
# Line 769 | Line 691 | public class SplittableRandom {
691      public LongStream longs(long streamSize, long randomNumberOrigin,
692                              long randomNumberBound) {
693          if (streamSize < 0L)
694 <            throw new IllegalArgumentException("negative Stream size");
694 >            throw new IllegalArgumentException(BadSize);
695          if (randomNumberOrigin >= randomNumberBound)
696 <            throw new IllegalArgumentException("bound must be greater than origin");
696 >            throw new IllegalArgumentException(BadRange);
697          return StreamSupport.longStream
698              (new RandomLongsSpliterator
699               (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
# Line 794 | Line 716 | public class SplittableRandom {
716       */
717      public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
718          if (randomNumberOrigin >= randomNumberBound)
719 <            throw new IllegalArgumentException("bound must be greater than origin");
719 >            throw new IllegalArgumentException(BadRange);
720          return StreamSupport.longStream
721              (new RandomLongsSpliterator
722               (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
# Line 813 | Line 735 | public class SplittableRandom {
735       */
736      public DoubleStream doubles(long streamSize) {
737          if (streamSize < 0L)
738 <            throw new IllegalArgumentException("negative Stream size");
738 >            throw new IllegalArgumentException(BadSize);
739          return StreamSupport.doubleStream
740              (new RandomDoublesSpliterator
741               (this, 0L, streamSize, Double.MAX_VALUE, 0.0),
# Line 855 | Line 777 | public class SplittableRandom {
777      public DoubleStream doubles(long streamSize, double randomNumberOrigin,
778                                  double randomNumberBound) {
779          if (streamSize < 0L)
780 <            throw new IllegalArgumentException("negative Stream size");
780 >            throw new IllegalArgumentException(BadSize);
781          if (!(randomNumberOrigin < randomNumberBound))
782 <            throw new IllegalArgumentException("bound must be greater than origin");
782 >            throw new IllegalArgumentException(BadRange);
783          return StreamSupport.doubleStream
784              (new RandomDoublesSpliterator
785               (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
# Line 880 | Line 802 | public class SplittableRandom {
802       */
803      public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
804          if (!(randomNumberOrigin < randomNumberBound))
805 <            throw new IllegalArgumentException("bound must be greater than origin");
805 >            throw new IllegalArgumentException(BadRange);
806          return StreamSupport.doubleStream
807              (new RandomDoublesSpliterator
808               (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
# Line 938 | Line 860 | public class SplittableRandom {
860              long i = index, f = fence;
861              if (i < f) {
862                  index = f;
863 +                SplittableRandom r = rng;
864                  int o = origin, b = bound;
865                  do {
866 <                    consumer.accept(rng.internalNextInt(o, b));
866 >                    consumer.accept(r.internalNextInt(o, b));
867                  } while (++i < f);
868              }
869          }
# Line 992 | Line 915 | public class SplittableRandom {
915              long i = index, f = fence;
916              if (i < f) {
917                  index = f;
918 +                SplittableRandom r = rng;
919                  long o = origin, b = bound;
920                  do {
921 <                    consumer.accept(rng.internalNextLong(o, b));
921 >                    consumer.accept(r.internalNextLong(o, b));
922                  } while (++i < f);
923              }
924          }
# Line 1047 | Line 971 | public class SplittableRandom {
971              long i = index, f = fence;
972              if (i < f) {
973                  index = f;
974 +                SplittableRandom r = rng;
975                  double o = origin, b = bound;
976                  do {
977 <                    consumer.accept(rng.internalNextDouble(o, b));
977 >                    consumer.accept(r.internalNextDouble(o, b));
978                  } while (++i < f);
979              }
980          }

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