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Comparing jsr166/src/main/java/util/SplittableRandom.java (file contents):
Revision 1.15 by dl, Fri Aug 9 12:12:10 2013 UTC vs.
Revision 1.31 by jsr166, Fri Feb 19 03:39:15 2016 UTC

# Line 25 | Line 25
25  
26   package java.util;
27  
28 import java.net.InetAddress;
28   import java.util.concurrent.atomic.AtomicLong;
29 < import java.util.Spliterator;
29 > import java.util.function.DoubleConsumer;
30   import java.util.function.IntConsumer;
31   import java.util.function.LongConsumer;
32 < import java.util.function.DoubleConsumer;
34 < import java.util.stream.StreamSupport;
32 > import java.util.stream.DoubleStream;
33   import java.util.stream.IntStream;
34   import java.util.stream.LongStream;
35 < import java.util.stream.DoubleStream;
35 > import java.util.stream.StreamSupport;
36  
37   /**
38   * A generator of uniform pseudorandom values applicable for use in
39   * (among other contexts) isolated parallel computations that may
40 < * generate subtasks. Class SplittableRandom supports methods for
40 > * generate subtasks. Class {@code SplittableRandom} supports methods for
41   * producing pseudorandom numbers of type {@code int}, {@code long},
42   * and {@code double} with similar usages as for class
43   * {@link java.util.Random} but differs in the following ways:
# Line 54 | Line 52 | import java.util.stream.DoubleStream;
52   * types and ranges, but similar properties are expected to hold, at
53   * least approximately, for others as well. The <em>period</em>
54   * (length of any series of generated values before it repeats) is at
55 < * least 2<sup>64</sup>. </li>
55 > * least 2<sup>64</sup>.
56   *
57 < * <li> Method {@link #split} constructs and returns a new
57 > * <li>Method {@link #split} constructs and returns a new
58   * SplittableRandom instance that shares no mutable state with the
59   * current instance. However, with very high probability, the
60   * values collectively generated by the two objects have the same
61   * statistical properties as if the same quantity of values were
62   * generated by a single thread using a single {@code
63 < * SplittableRandom} object.  </li>
63 > * SplittableRandom} object.
64   *
65   * <li>Instances of SplittableRandom are <em>not</em> thread-safe.
66   * They are designed to be split, not shared, across threads. For
# Line 73 | Line 71 | import java.util.stream.DoubleStream;
71   *
72   * <li>This class provides additional methods for generating random
73   * streams, that employ the above techniques when used in {@code
74 < * stream.parallel()} mode.</li>
74 > * stream.parallel()} mode.
75   *
76   * </ul>
77   *
78 + * <p>Instances of {@code SplittableRandom} are not cryptographically
79 + * secure.  Consider instead using {@link java.security.SecureRandom}
80 + * in security-sensitive applications. Additionally,
81 + * default-constructed instances do not use a cryptographically random
82 + * seed unless the {@linkplain System#getProperty system property}
83 + * {@code java.util.secureRandomSeed} is set to {@code true}.
84 + *
85   * @author  Guy Steele
86   * @author  Doug Lea
87   * @since   1.8
88   */
89 < public class SplittableRandom {
89 > public final class SplittableRandom {
90  
91      /*
92       * Implementation Overview.
# Line 101 | Line 106 | public class SplittableRandom {
106       * Methods nextLong, nextInt, and derivatives do not return the
107       * sequence (seed) values, but instead a hash-like bit-mix of
108       * their bits, producing more independently distributed sequences.
109 <     * For nextLong, the mix64 bit-mixing function computes the same
110 <     * value as the "64-bit finalizer" function in Austin Appleby's
111 <     * MurmurHash3 algorithm.  See
112 <     * http://code.google.com/p/smhasher/wiki/MurmurHash3 , which
113 <     * comments: "The constants for the finalizers were generated by a
114 <     * simple simulated-annealing algorithm, and both avalanche all
115 <     * 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.
109 >     * For nextLong, the mix64 function is based on David Stafford's
110 >     * (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html)
111 >     * "Mix13" variant of the "64-bit finalizer" function in Austin
112 >     * Appleby's MurmurHash3 algorithm (see
113 >     * http://code.google.com/p/smhasher/wiki/MurmurHash3). The mix32
114 >     * function is based on Stafford's Mix04 mix function, but returns
115 >     * the upper 32 bits cast as int.
116       *
117       * The split operation uses the current generator to form the seed
118       * and gamma for another SplittableRandom.  To conservatively
119       * avoid potential correlations between seed and value generation,
120 <     * gamma selection (method nextGamma) uses the "Mix13" constants
121 <     * for MurmurHash3 described by David Stafford
122 <     * (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html)
123 <     * To avoid potential weaknesses in bit-mixing transformations, we
124 <     * restrict gammas to odd values with at least 12 and no more than
125 <     * 52 bits set.  Rather than rejecting candidates with too few or
126 <     * too many bits set, method nextGamma flips some bits (which has
127 <     * 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
120 >     * gamma selection (method mixGamma) uses different
121 >     * (Murmurhash3's) mix constants.  To avoid potential weaknesses
122 >     * in bit-mixing transformations, we restrict gammas to odd values
123 >     * with at least 24 0-1 or 1-0 bit transitions.  Rather than
124 >     * rejecting candidates with too few or too many bits set, method
125 >     * mixGamma flips some bits (which has the effect of mapping at
126 >     * most 4 to any given gamma value).  This reduces the effective
127 >     * set of 64bit odd gamma values by about 2%, and serves as an
128       * automated screening for sequence constant selection that is
129       * left as an empirical decision in some other hashing and crypto
130       * algorithms.
# Line 134 | Line 135 | public class SplittableRandom {
135       * avalanching.
136       *
137       * The default (no-argument) constructor, in essence, invokes
138 <     * split() for a common "seeder" SplittableRandom.  Unlike other
139 <     * cases, this split must be performed in a thread-safe manner, so
140 <     * we use an AtomicLong to represent the seed rather than use an
141 <     * explicit SplittableRandom. To bootstrap the seeder, we start
142 <     * off using a seed based on current time and host. This serves as
143 <     * a slimmed-down (and insecure) variant of SecureRandom that also
144 <     * avoids stalls that may occur when using /dev/random.
138 >     * split() for a common "defaultGen" SplittableRandom.  Unlike
139 >     * other cases, this split must be performed in a thread-safe
140 >     * manner, so we use an AtomicLong to represent the seed rather
141 >     * than use an explicit SplittableRandom. To bootstrap the
142 >     * defaultGen, we start off using a seed based on current time
143 >     * unless the java.util.secureRandomSeed property is set. This
144 >     * serves as a slimmed-down (and insecure) variant of SecureRandom
145 >     * that also avoids stalls that may occur when using /dev/random.
146       *
147       * It is a relatively simple matter to apply the basic design here
148       * to use 128 bit seeds. However, emulating 128bit arithmetic and
# Line 153 | Line 155 | public class SplittableRandom {
155       */
156  
157      /**
158 <     * The initial gamma value for (unsplit) SplittableRandoms. Must
159 <     * be odd with at least 12 and no more than 52 bits set. Currently
158 <     * set to the golden ratio scaled to 64bits.
158 >     * The golden ratio scaled to 64bits, used as the initial gamma
159 >     * value for (unsplit) SplittableRandoms.
160       */
161 <    private static final long INITIAL_GAMMA = 0x9e3779b97f4a7c15L;
161 >    private static final long GOLDEN_GAMMA = 0x9e3779b97f4a7c15L;
162  
163      /**
164       * The least non-zero value returned by nextDouble(). This value
165       * is scaled by a random value of 53 bits to produce a result.
166       */
167 <    private static final double DOUBLE_UNIT = 1.0 / (1L << 53);
167 >    private static final double DOUBLE_UNIT = 0x1.0p-53; // 1.0 / (1L << 53);
168  
169      /**
170       * The seed. Updated only via method nextSeed.
# Line 184 | Line 185 | public class SplittableRandom {
185      }
186  
187      /**
188 <     * Computes MurmurHash3 64bit mix function.
188 >     * Computes Stafford variant 13 of 64bit mix function.
189       */
190      private static long mix64(long z) {
191 <        z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
192 <        z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
193 <        return z ^ (z >>> 33);
191 >        z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L;
192 >        z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
193 >        return z ^ (z >>> 31);
194      }
195  
196      /**
197 <     * Returns the 32 high bits of mix64(z) as int.
197 >     * Returns the 32 high bits of Stafford variant 4 mix64 function as int.
198       */
199      private static int mix32(long z) {
200 <        z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
201 <        return (int)(((z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L) >>> 32);
200 >        z = (z ^ (z >>> 33)) * 0x62a9d9ed799705f5L;
201 >        return (int)(((z ^ (z >>> 28)) * 0xcb24d0a5c88c35b3L) >>> 32);
202      }
203  
204      /**
205       * Returns the gamma value to use for a new split instance.
206       */
207 <    private static long nextGamma(long z) {
208 <        z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L; // Stafford "Mix13"
209 <        z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
210 <        z = (z ^ (z >>> 31)) | 1L; // force to be odd
211 <        int n = Long.bitCount(z);  // ensure enough 0 and 1 bits
212 <        return (n < 12 || n > 52) ? z ^ 0xaaaaaaaaaaaaaaaaL : z;
207 >    private static long mixGamma(long z) {
208 >        z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL; // MurmurHash3 mix constants
209 >        z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
210 >        z = (z ^ (z >>> 33)) | 1L;                  // force to be odd
211 >        int n = Long.bitCount(z ^ (z >>> 1));       // ensure enough transitions
212 >        return (n < 24) ? z ^ 0xaaaaaaaaaaaaaaaaL : z;
213      }
214  
215      /**
# Line 221 | Line 222 | public class SplittableRandom {
222      /**
223       * The seed generator for default constructors.
224       */
225 <    private static final AtomicLong seeder =
225 <        new AtomicLong(mix64((((long)hashedHostAddress()) << 32) ^
226 <                             System.currentTimeMillis()) ^
227 <                       mix64(System.nanoTime()));
225 >    private static final AtomicLong defaultGen = new AtomicLong(initialSeed());
226  
227 <    /**
228 <     * Returns hash of local host IP address, if available; else 0.
229 <     */
230 <    private static int hashedHostAddress() {
231 <        try {
232 <            return InetAddress.getLocalHost().hashCode();
233 <        } catch (Exception ex) {
234 <            return 0;
235 <        }
227 >    private static long initialSeed() {
228 >        if (java.security.AccessController.doPrivileged(
229 >            new java.security.PrivilegedAction<Boolean>() {
230 >                public Boolean run() {
231 >                    return Boolean.getBoolean("java.util.secureRandomSeed");
232 >                }})) {
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;
238 >        }
239 >        return (mix64(System.currentTimeMillis()) ^
240 >                mix64(System.nanoTime()));
241      }
242  
243      // IllegalArgumentException messages
244 <    static final String BadBound = "bound must be positive";
245 <    static final String BadRange = "bound must be greater than origin";
246 <    static final String BadSize  = "size must be non-negative";
244 >    static final String BAD_BOUND = "bound must be positive";
245 >    static final String BAD_RANGE = "bound must be greater than origin";
246 >    static final String BAD_SIZE  = "size must be non-negative";
247  
248      /*
249       * Internal versions of nextX methods used by streams, as well as
# Line 361 | Line 364 | public class SplittableRandom {
364       * @param seed the initial seed
365       */
366      public SplittableRandom(long seed) {
367 <        this(seed, INITIAL_GAMMA);
367 >        this(seed, GOLDEN_GAMMA);
368      }
369  
370      /**
# Line 370 | Line 373 | public class SplittableRandom {
373       * of those of any other instances in the current program; and
374       * may, and typically does, vary across program invocations.
375       */
376 <    public SplittableRandom() { // emulate seeder.split()
377 <        this.gamma = nextGamma(this.seed = seeder.addAndGet(INITIAL_GAMMA));
376 >    public SplittableRandom() { // emulate defaultGen.split()
377 >        long s = defaultGen.getAndAdd(2 * GOLDEN_GAMMA);
378 >        this.seed = mix64(s);
379 >        this.gamma = mixGamma(s + GOLDEN_GAMMA);
380      }
381  
382      /**
# Line 389 | Line 394 | public class SplittableRandom {
394       * @return the new SplittableRandom instance
395       */
396      public SplittableRandom split() {
397 <        long s = nextSeed();
393 <        return new SplittableRandom(s, nextGamma(s));
397 >        return new SplittableRandom(nextLong(), mixGamma(nextSeed()));
398      }
399  
400      /**
# Line 406 | Line 410 | public class SplittableRandom {
410       * Returns a pseudorandom {@code int} value between zero (inclusive)
411       * and the specified bound (exclusive).
412       *
413 <     * @param bound the bound on the random number to be returned.  Must be
410 <     *        positive.
413 >     * @param bound the upper bound (exclusive).  Must be positive.
414       * @return a pseudorandom {@code int} value between zero
415       *         (inclusive) and the bound (exclusive)
416 <     * @throws IllegalArgumentException if the bound is less than zero
416 >     * @throws IllegalArgumentException if {@code bound} is not positive
417       */
418      public int nextInt(int bound) {
419          if (bound <= 0)
420 <            throw new IllegalArgumentException(BadBound);
420 >            throw new IllegalArgumentException(BAD_BOUND);
421          // Specialize internalNextInt for origin 0
422          int r = mix32(nextSeed());
423          int m = bound - 1;
# Line 442 | Line 445 | public class SplittableRandom {
445       */
446      public int nextInt(int origin, int bound) {
447          if (origin >= bound)
448 <            throw new IllegalArgumentException(BadRange);
448 >            throw new IllegalArgumentException(BAD_RANGE);
449          return internalNextInt(origin, bound);
450      }
451  
# Line 459 | Line 462 | public class SplittableRandom {
462       * Returns a pseudorandom {@code long} value between zero (inclusive)
463       * and the specified bound (exclusive).
464       *
465 <     * @param bound the bound on the random number to be returned.  Must be
463 <     *        positive.
465 >     * @param bound the upper bound (exclusive).  Must be positive.
466       * @return a pseudorandom {@code long} value between zero
467       *         (inclusive) and the bound (exclusive)
468 <     * @throws IllegalArgumentException if {@code bound} is less than zero
468 >     * @throws IllegalArgumentException if {@code bound} is not positive
469       */
470      public long nextLong(long bound) {
471          if (bound <= 0)
472 <            throw new IllegalArgumentException(BadBound);
472 >            throw new IllegalArgumentException(BAD_BOUND);
473          // Specialize internalNextLong for origin 0
474          long r = mix64(nextSeed());
475          long m = bound - 1;
# Line 495 | Line 497 | public class SplittableRandom {
497       */
498      public long nextLong(long origin, long bound) {
499          if (origin >= bound)
500 <            throw new IllegalArgumentException(BadRange);
500 >            throw new IllegalArgumentException(BAD_RANGE);
501          return internalNextLong(origin, bound);
502      }
503  
# Line 504 | Line 506 | public class SplittableRandom {
506       * (inclusive) and one (exclusive).
507       *
508       * @return a pseudorandom {@code double} value between zero
509 <     * (inclusive) and one (exclusive)
509 >     *         (inclusive) and one (exclusive)
510       */
511      public double nextDouble() {
512          return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT;
# Line 514 | Line 516 | public class SplittableRandom {
516       * Returns a pseudorandom {@code double} value between 0.0
517       * (inclusive) and the specified bound (exclusive).
518       *
519 <     * @param bound the bound on the random number to be returned.  Must be
518 <     *        positive.
519 >     * @param bound the upper bound (exclusive).  Must be positive.
520       * @return a pseudorandom {@code double} value between zero
521       *         (inclusive) and the bound (exclusive)
522 <     * @throws IllegalArgumentException if {@code bound} is less than zero
522 >     * @throws IllegalArgumentException if {@code bound} is not positive
523       */
524      public double nextDouble(double bound) {
525          if (!(bound > 0.0))
526 <            throw new IllegalArgumentException(BadBound);
526 >            throw new IllegalArgumentException(BAD_BOUND);
527          double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound;
528          return (result < bound) ?  result : // correct for rounding
529              Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
# Line 533 | Line 534 | public class SplittableRandom {
534       * origin (inclusive) and bound (exclusive).
535       *
536       * @param origin the least value returned
537 <     * @param bound the upper bound
537 >     * @param bound the upper bound (exclusive)
538       * @return a pseudorandom {@code double} value between the origin
539       *         (inclusive) and the bound (exclusive)
540       * @throws IllegalArgumentException if {@code origin} is greater than
# Line 541 | Line 542 | public class SplittableRandom {
542       */
543      public double nextDouble(double origin, double bound) {
544          if (!(origin < bound))
545 <            throw new IllegalArgumentException(BadRange);
545 >            throw new IllegalArgumentException(BAD_RANGE);
546          return internalNextDouble(origin, bound);
547      }
548  
# Line 558 | Line 559 | public class SplittableRandom {
559      // maintenance purposes the small differences across forms.
560  
561      /**
562 <     * Returns a stream producing the given {@code streamSize} number of
563 <     * pseudorandom {@code int} values.
562 >     * Returns a stream producing the given {@code streamSize} number
563 >     * of pseudorandom {@code int} values from this generator and/or
564 >     * one split from it.
565       *
566       * @param streamSize the number of values to generate
567       * @return a stream of pseudorandom {@code int} values
# Line 568 | Line 570 | public class SplittableRandom {
570       */
571      public IntStream ints(long streamSize) {
572          if (streamSize < 0L)
573 <            throw new IllegalArgumentException(BadSize);
573 >            throw new IllegalArgumentException(BAD_SIZE);
574          return StreamSupport.intStream
575              (new RandomIntsSpliterator
576               (this, 0L, streamSize, Integer.MAX_VALUE, 0),
# Line 577 | Line 579 | public class SplittableRandom {
579  
580      /**
581       * Returns an effectively unlimited stream of pseudorandom {@code int}
582 <     * values.
582 >     * values from this generator and/or one split from it.
583       *
584       * @implNote This method is implemented to be equivalent to {@code
585       * ints(Long.MAX_VALUE)}.
# Line 592 | Line 594 | public class SplittableRandom {
594      }
595  
596      /**
597 <     * Returns a stream producing the given {@code streamSize} number of
598 <     * pseudorandom {@code int} values, each conforming to the given
599 <     * origin and bound.
597 >     * Returns a stream producing the given {@code streamSize} number
598 >     * of pseudorandom {@code int} values from this generator and/or one split
599 >     * from it; each value conforms to the given origin (inclusive) and bound
600 >     * (exclusive).
601       *
602       * @param streamSize the number of values to generate
603 <     * @param randomNumberOrigin the origin of each random value
604 <     * @param randomNumberBound the bound of each random value
603 >     * @param randomNumberOrigin the origin (inclusive) of each random value
604 >     * @param randomNumberBound the bound (exclusive) of each random value
605       * @return a stream of pseudorandom {@code int} values,
606 <     *         each with the given origin and bound
606 >     *         each with the given origin (inclusive) and bound (exclusive)
607       * @throws IllegalArgumentException if {@code streamSize} is
608       *         less than zero, or {@code randomNumberOrigin}
609       *         is greater than or equal to {@code randomNumberBound}
# Line 608 | Line 611 | public class SplittableRandom {
611      public IntStream ints(long streamSize, int randomNumberOrigin,
612                            int randomNumberBound) {
613          if (streamSize < 0L)
614 <            throw new IllegalArgumentException(BadSize);
614 >            throw new IllegalArgumentException(BAD_SIZE);
615          if (randomNumberOrigin >= randomNumberBound)
616 <            throw new IllegalArgumentException(BadRange);
616 >            throw new IllegalArgumentException(BAD_RANGE);
617          return StreamSupport.intStream
618              (new RandomIntsSpliterator
619               (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
# Line 619 | Line 622 | public class SplittableRandom {
622  
623      /**
624       * Returns an effectively unlimited stream of pseudorandom {@code
625 <     * int} values, each conforming to the given origin and bound.
625 >     * int} values from this generator and/or one split from it; each value
626 >     * conforms to the given origin (inclusive) and bound (exclusive).
627       *
628       * @implNote This method is implemented to be equivalent to {@code
629       * ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
630       *
631 <     * @param randomNumberOrigin the origin of each random value
632 <     * @param randomNumberBound the bound of each random value
631 >     * @param randomNumberOrigin the origin (inclusive) of each random value
632 >     * @param randomNumberBound the bound (exclusive) of each random value
633       * @return a stream of pseudorandom {@code int} values,
634 <     *         each with the given origin and bound
634 >     *         each with the given origin (inclusive) and bound (exclusive)
635       * @throws IllegalArgumentException if {@code randomNumberOrigin}
636       *         is greater than or equal to {@code randomNumberBound}
637       */
638      public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
639          if (randomNumberOrigin >= randomNumberBound)
640 <            throw new IllegalArgumentException(BadRange);
640 >            throw new IllegalArgumentException(BAD_RANGE);
641          return StreamSupport.intStream
642              (new RandomIntsSpliterator
643               (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
# Line 641 | Line 645 | public class SplittableRandom {
645      }
646  
647      /**
648 <     * Returns a stream producing the given {@code streamSize} number of
649 <     * pseudorandom {@code long} values.
648 >     * Returns a stream producing the given {@code streamSize} number
649 >     * of pseudorandom {@code long} values from this generator and/or
650 >     * one split from it.
651       *
652       * @param streamSize the number of values to generate
653       * @return a stream of pseudorandom {@code long} values
# Line 651 | Line 656 | public class SplittableRandom {
656       */
657      public LongStream longs(long streamSize) {
658          if (streamSize < 0L)
659 <            throw new IllegalArgumentException(BadSize);
659 >            throw new IllegalArgumentException(BAD_SIZE);
660          return StreamSupport.longStream
661              (new RandomLongsSpliterator
662               (this, 0L, streamSize, Long.MAX_VALUE, 0L),
# Line 659 | Line 664 | public class SplittableRandom {
664      }
665  
666      /**
667 <     * Returns an effectively unlimited stream of pseudorandom {@code long}
668 <     * values.
667 >     * Returns an effectively unlimited stream of pseudorandom {@code
668 >     * long} values from this generator and/or one split from it.
669       *
670       * @implNote This method is implemented to be equivalent to {@code
671       * longs(Long.MAX_VALUE)}.
# Line 676 | Line 681 | public class SplittableRandom {
681  
682      /**
683       * Returns a stream producing the given {@code streamSize} number of
684 <     * pseudorandom {@code long} values, each conforming to the
685 <     * given origin and bound.
684 >     * pseudorandom {@code long} values from this generator and/or one split
685 >     * from it; each value conforms to the given origin (inclusive) and bound
686 >     * (exclusive).
687       *
688       * @param streamSize the number of values to generate
689 <     * @param randomNumberOrigin the origin of each random value
690 <     * @param randomNumberBound the bound of each random value
689 >     * @param randomNumberOrigin the origin (inclusive) of each random value
690 >     * @param randomNumberBound the bound (exclusive) of each random value
691       * @return a stream of pseudorandom {@code long} values,
692 <     *         each with the given origin and bound
692 >     *         each with the given origin (inclusive) and bound (exclusive)
693       * @throws IllegalArgumentException if {@code streamSize} is
694       *         less than zero, or {@code randomNumberOrigin}
695       *         is greater than or equal to {@code randomNumberBound}
# Line 691 | Line 697 | public class SplittableRandom {
697      public LongStream longs(long streamSize, long randomNumberOrigin,
698                              long randomNumberBound) {
699          if (streamSize < 0L)
700 <            throw new IllegalArgumentException(BadSize);
700 >            throw new IllegalArgumentException(BAD_SIZE);
701          if (randomNumberOrigin >= randomNumberBound)
702 <            throw new IllegalArgumentException(BadRange);
702 >            throw new IllegalArgumentException(BAD_RANGE);
703          return StreamSupport.longStream
704              (new RandomLongsSpliterator
705               (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
# Line 702 | Line 708 | public class SplittableRandom {
708  
709      /**
710       * Returns an effectively unlimited stream of pseudorandom {@code
711 <     * long} values, each conforming to the given origin and bound.
711 >     * long} values from this generator and/or one split from it; each value
712 >     * conforms to the given origin (inclusive) and bound (exclusive).
713       *
714       * @implNote This method is implemented to be equivalent to {@code
715       * longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
716       *
717 <     * @param randomNumberOrigin the origin of each random value
718 <     * @param randomNumberBound the bound of each random value
717 >     * @param randomNumberOrigin the origin (inclusive) of each random value
718 >     * @param randomNumberBound the bound (exclusive) of each random value
719       * @return a stream of pseudorandom {@code long} values,
720 <     *         each with the given origin and bound
720 >     *         each with the given origin (inclusive) and bound (exclusive)
721       * @throws IllegalArgumentException if {@code randomNumberOrigin}
722       *         is greater than or equal to {@code randomNumberBound}
723       */
724      public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
725          if (randomNumberOrigin >= randomNumberBound)
726 <            throw new IllegalArgumentException(BadRange);
726 >            throw new IllegalArgumentException(BAD_RANGE);
727          return StreamSupport.longStream
728              (new RandomLongsSpliterator
729               (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
# Line 725 | Line 732 | public class SplittableRandom {
732  
733      /**
734       * Returns a stream producing the given {@code streamSize} number of
735 <     * pseudorandom {@code double} values, each between zero
736 <     * (inclusive) and one (exclusive).
735 >     * pseudorandom {@code double} values from this generator and/or one split
736 >     * from it; each value is between zero (inclusive) and one (exclusive).
737       *
738       * @param streamSize the number of values to generate
739       * @return a stream of {@code double} values
# Line 735 | Line 742 | public class SplittableRandom {
742       */
743      public DoubleStream doubles(long streamSize) {
744          if (streamSize < 0L)
745 <            throw new IllegalArgumentException(BadSize);
745 >            throw new IllegalArgumentException(BAD_SIZE);
746          return StreamSupport.doubleStream
747              (new RandomDoublesSpliterator
748               (this, 0L, streamSize, Double.MAX_VALUE, 0.0),
# Line 744 | Line 751 | public class SplittableRandom {
751  
752      /**
753       * Returns an effectively unlimited stream of pseudorandom {@code
754 <     * double} values, each between zero (inclusive) and one
755 <     * (exclusive).
754 >     * double} values from this generator and/or one split from it; each value
755 >     * is between zero (inclusive) and one (exclusive).
756       *
757       * @implNote This method is implemented to be equivalent to {@code
758       * doubles(Long.MAX_VALUE)}.
# Line 761 | Line 768 | public class SplittableRandom {
768  
769      /**
770       * Returns a stream producing the given {@code streamSize} number of
771 <     * pseudorandom {@code double} values, each conforming to the
772 <     * given origin and bound.
771 >     * pseudorandom {@code double} values from this generator and/or one split
772 >     * from it; each value conforms to the given origin (inclusive) and bound
773 >     * (exclusive).
774       *
775       * @param streamSize the number of values to generate
776 <     * @param randomNumberOrigin the origin of each random value
777 <     * @param randomNumberBound the bound of each random value
776 >     * @param randomNumberOrigin the origin (inclusive) of each random value
777 >     * @param randomNumberBound the bound (exclusive) of each random value
778       * @return a stream of pseudorandom {@code double} values,
779 <     * each with the given origin and bound
779 >     *         each with the given origin (inclusive) and bound (exclusive)
780       * @throws IllegalArgumentException if {@code streamSize} is
781 <     * less than zero
781 >     *         less than zero
782       * @throws IllegalArgumentException if {@code randomNumberOrigin}
783       *         is greater than or equal to {@code randomNumberBound}
784       */
785      public DoubleStream doubles(long streamSize, double randomNumberOrigin,
786                                  double randomNumberBound) {
787          if (streamSize < 0L)
788 <            throw new IllegalArgumentException(BadSize);
788 >            throw new IllegalArgumentException(BAD_SIZE);
789          if (!(randomNumberOrigin < randomNumberBound))
790 <            throw new IllegalArgumentException(BadRange);
790 >            throw new IllegalArgumentException(BAD_RANGE);
791          return StreamSupport.doubleStream
792              (new RandomDoublesSpliterator
793               (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
# Line 788 | Line 796 | public class SplittableRandom {
796  
797      /**
798       * Returns an effectively unlimited stream of pseudorandom {@code
799 <     * double} values, each conforming to the given origin and bound.
799 >     * double} values from this generator and/or one split from it; each value
800 >     * conforms to the given origin (inclusive) and bound (exclusive).
801       *
802       * @implNote This method is implemented to be equivalent to {@code
803       * doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
804       *
805 <     * @param randomNumberOrigin the origin of each random value
806 <     * @param randomNumberBound the bound of each random value
805 >     * @param randomNumberOrigin the origin (inclusive) of each random value
806 >     * @param randomNumberBound the bound (exclusive) of each random value
807       * @return a stream of pseudorandom {@code double} values,
808 <     * each with the given origin and bound
808 >     *         each with the given origin (inclusive) and bound (exclusive)
809       * @throws IllegalArgumentException if {@code randomNumberOrigin}
810       *         is greater than or equal to {@code randomNumberBound}
811       */
812      public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
813          if (!(randomNumberOrigin < randomNumberBound))
814 <            throw new IllegalArgumentException(BadRange);
814 >            throw new IllegalArgumentException(BAD_RANGE);
815          return StreamSupport.doubleStream
816              (new RandomDoublesSpliterator
817               (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
# Line 817 | Line 826 | public class SplittableRandom {
826       * approach. The long and double versions of this class are
827       * identical except for types.
828       */
829 <    static final class RandomIntsSpliterator implements Spliterator.OfInt {
829 >    private static final class RandomIntsSpliterator
830 >            implements Spliterator.OfInt {
831          final SplittableRandom rng;
832          long index;
833          final long fence;
# Line 872 | Line 882 | public class SplittableRandom {
882      /**
883       * Spliterator for long streams.
884       */
885 <    static final class RandomLongsSpliterator implements Spliterator.OfLong {
885 >    private static final class RandomLongsSpliterator
886 >            implements Spliterator.OfLong {
887          final SplittableRandom rng;
888          long index;
889          final long fence;
# Line 928 | Line 939 | public class SplittableRandom {
939      /**
940       * Spliterator for double streams.
941       */
942 <    static final class RandomDoublesSpliterator implements Spliterator.OfDouble {
942 >    private static final class RandomDoublesSpliterator
943 >            implements Spliterator.OfDouble {
944          final SplittableRandom rng;
945          long index;
946          final long fence;

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