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root/jsr166/jsr166/src/main/java/util/SplittableRandom.java

Comparing jsr166/src/main/java/util/SplittableRandom.java (file contents):
Revision 1.2 by dl, Wed Jul 10 23:42:43 2013 UTC vs.
Revision 1.14 by dl, Mon Aug 5 13:58:02 2013 UTC

#	Line 25 | Line 25
25
26		package java.util;
27
28	+	import java.security.SecureRandom;
29		import java.util.concurrent.atomic.AtomicLong;
30		import java.util.Spliterator;
31		import java.util.function.IntConsumer;
#	Line 35 | Line 36 | import java.util.stream.IntStream;
36		import java.util.stream.LongStream;
37		import java.util.stream.DoubleStream;
38
38	–
39		/**
40		* A generator of uniform pseudorandom values applicable for use in
41		* (among other contexts) isolated parallel computations that may
42		* generate subtasks. Class SplittableRandom supports methods for
43	<	* producing pseudorandom nunmbers of type {@code int}, {@code long},
43	>	* producing pseudorandom numbers of type {@code int}, {@code long},
44		* and {@code double} with similar usages as for class
45	<	* {@link java.util.Random} but differs in the following ways: <ul>
45	>	* {@link java.util.Random} but differs in the following ways:
46	>	*
47	>	* <ul>
48		*
49		* <li>Series of generated values pass the DieHarder suite testing
50		* independence and uniformity properties of random number generators.
#	Line 50 | Line 52 | import java.util.stream.DoubleStream;
52		* href="http://www.phy.duke.edu/~rgb/General/dieharder.php"> version
53		* 3.31.1</a>.) These tests validate only the methods for certain
54		* types and ranges, but similar properties are expected to hold, at
55	<	* least approximately, for others as well.  </li>
55	>	* least approximately, for others as well. The <em>period</em>
56	>	* (length of any series of generated values before it repeats) is at
57	>	* least 2<sup>64</sup>. </li>
58		*
59		* <li> Method {@link #split} constructs and returns a new
60		* SplittableRandom instance that shares no mutable state with the
61	<	* current instance. However, with very high probability, the set of
62	<	* values collectively generated by the two objects has the same
61	>	* current instance. However, with very high probability, the
62	>	* values collectively generated by the two objects have the same
63		* statistical properties as if the same quantity of values were
64		* generated by a single thread using a single {@code
65		* SplittableRandom} object.  </li>
#	Line 97 | Line 101 | public class SplittableRandom {
101		* Random-Number Generation for Dynamic-Multithreading Platforms",
102		* PPoPP 2012, but improves and extends it in several ways.
103		*
104	<	* The primary update step is simply to add a constant ("gamma")
105	<	* to the current seed, modulo a prime ("George"). However, the
106	<	* nextLong and nextInt methods do not return this value, but
107	<	* instead the results of bit-mixing transformations that produce
108	<	* more uniformly distributed sequences.
104	>	* The primary update step (see method nextSeed()) is simply to
105	>	* add a constant ("gamma") to the current seed, modulo a prime
106	>	* ("George"). However, the nextLong and nextInt methods do not
107	>	* return this value, but instead the results of bit-mixing
108	>	* transformations that produce more uniformly distributed
109	>	* sequences.
110		*
111		* "George" is the otherwise nameless (because it cannot be
112		* represented) prime number 2^64+13. Using a prime number larger
#	Line 110 | Line 115 | public class SplittableRandom {
115		* are encountered; see method addGammaModGeorge. For this to
116		* work, initial gamma values must be at least 13.
117		*
113	–	* The value of gamma differs for each instance across a series of
114	–	* splits, and is generated using a slightly stripped-down variant
115	–	* of the same algorithm, but operating across calls to split(),
116	–	* not calls to nextSeed(): Each instance carries the state of
117	–	* this generator as nextSplit, and uses mix64(nextSplit) as its
118	–	* own gamma value. Computations of gammas themselves use a fixed
119	–	* constant as the second argument to the addGammaModGeorge
120	–	* function, GAMMA_GAMMA, a "genuinely random" number from a
121	–	* radioactive decay reading (obtained from
122	–	* http://www.fourmilab.ch/hotbits/) meeting the above range
123	–	* constraint. Using a fixed constant maintains the invariant that
124	–	* the value of gamma is the same for every instance that is at
125	–	* the same split-distance from their common root. (Note: there is
126	–	* nothing especially magic about obtaining this constant from a
127	–	* "truly random" physical source rather than just choosing one
128	–	* arbitrarily; using "hotbits" was merely an aesthetically pleasing
129	–	* choice.  In either case, good statistical behavior of the
130	–	* algorithm should be, and was, verified by using the DieHarder
131	–	* test suite.)
132	–	*
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
121		* http://code.google.com/p/smhasher/wiki/MurmurHash3 , which
122		* comments: "The constants for the finalizers were generated by a
123		* simple simulated-annealing algorithm, and both avalanche all
124	<	* bits of 'h' to within 0.25% bias." It also appears to work to
125	<	* use instead any of the variants proposed by David Stafford at
126	<	* http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html
127	<	* but these variants have not yet been tested as thoroughly
128	<	* in the context of the implementation of SplittableRandom.
124	>	* bits of 'h' to within 0.25% bias."
125	>	*
126	>	* The value of gamma differs for each instance across a series of
127	>	* splits, and is generated using an independent variant of the
128	>	* same algorithm, but operating across calls to split(), not
129	>	* calls to nextSeed(): Each instance carries the state of this
130	>	* generator as nextSplit. Gammas are treated as 57bit values,
131	>	* advancing by adding GAMMA_GAMMA mod GAMMA_PRIME, and bit-mixed
132	>	* with a 57-bit version of mix, using the "Mix13" multiplicative
133	>	* constants for MurmurHash3 described by David Stafford
134	>	* (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html).
135	>	* The value of GAMMA_GAMMA is arbitrary (except must be at least
136	>	* 13 and less than GAMMA_PRIME), but because it serves as the
137	>	* base of split sequences, should be subject to validation of
138	>	* consequent random number quality metrics.
139		*
140		* The mix32 function used for nextInt just consists of two of the
141	<	* five lines of mix64; avalanche testing shows that the 64-bit result
142	<	* has its top 32 bits avalanched well, though not the bottom 32 bits.
143	<	* DieHarder tests show that it is adequate for generating one
144	<	* random int from the 64-bit result of nextSeed.
141	>	* five lines of mix64; avalanche testing shows that the 64-bit
142	>	* result has its top 32 bits avalanched well, though not the
143	>	* bottom 32 bits.  DieHarder tests show that it is adequate for
144	>	* generating one random int from the 64-bit result of nextSeed.
145		*
146		* Support for the default (no-argument) constructor relies on an
147		* AtomicLong (defaultSeedGenerator) to help perform the
#	Line 154 | Line 149 | public class SplittableRandom {
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 System.nanotime(),
153	<	* and update using another "genuinely random" constant
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
#	Line 164 | Line 159 | public class SplittableRandom {
159		*/
160
161		/**
162	<	* The "genuinely random" value for producing new gamma values.
163	<	* The value is arbitrary, subject to the requirement that it be
164	<	* greater or equal to 13.
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.
178		*/
179	<	private static final long GAMMA_GAMMA = 0xF2281E2DBA6606F3L;
179	>	private static final long DEFAULT_SEED_GAMMA = 0x9e3779b97f4a7c15L;
180
181		/**
182	<	* The "genuinely random" seed update value for default constructors.
183	<	* The value is arbitrary, subject to the requirement that it be
176	<	* greater or equal to 13.
182	>	* The value 13 with 64bit sign bit set. Used in the signed
183	>	* comparison in addGammaModGeorge.
184		*/
185	<	private static final long DEFAULT_SEED_GAMMA = 0xBD24B73A95FB84D9L;
185	>	private static final long BOTTOM13 = 0x800000000000000DL;
186	>
187	>	/**
188	>	* The least non-zero value returned by nextDouble(). This value
189	>	* is scaled by a random value of 53 bits to produce a result.
190	>	*/
191	>	private static final double DOUBLE_UNIT = 1.0 / (1L << 53);
192
193		/**
194		* The next seed for default constructors.
195		*/
196		private static final AtomicLong defaultSeedGenerator =
197	<	new AtomicLong(System.nanoTime());
197	>	new AtomicLong(getInitialDefaultSeed());
198
199		/**
200		* The seed, updated only via method nextSeed.
#	Line 200 | Line 213 | public class SplittableRandom {
213		private final long nextSplit;
214
215		/**
203	–	* Internal constructor used by all other constructors and by
204	–	* method split. Establishes the initial seed for this instance,
205	–	* and uses the given splitSeed to establish gamma, as well as the
206	–	* nextSplit to use by this instance.
207	–	*/
208	–	private SplittableRandom(long seed, long splitSeed) {
209	–	this.seed = seed;
210	–	long s = splitSeed, g;
211	–	do { // ensure gamma >= 13, considered as an unsigned integer
212	–	s = addGammaModGeorge(s, GAMMA_GAMMA);
213	–	g = mix64(s);
214	–	} while (Long.compareUnsigned(g, 13L) < 0);
215	–	this.gamma = g;
216	–	this.nextSplit = s;
217	–	}
218	–
219	–	/**
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
#	Line 226 | Line 222 | public class SplittableRandom {
222		* George < 2^64; thus we need only a conditional, not a loop,
223		* to be sure of getting a representable value.
224		*
225	<	* @param s a seed value
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	<	if (Long.compareUnsigned(p, g) >= 0)
235	<	return p;
236	<	long q = p - 13L;
237	<	return (Long.compareUnsigned(p, 13L) >= 0) ? q : (q + g);
238	<	}
239	<
240	<	/**
241	<	* Updates in-place and returns seed.
242	<	* See above for explanation.
243	<	*/
244	<	private long nextSeed() {
245	<	return seed = addGammaModGeorge(seed, gamma);
234	>	return (p >= s) ? p : ((p >= BOTTOM13) ? p  : p + g) - 13L;
235		}
236
237		/**
#	Line 269 | Line 258 | public class SplittableRandom {
258		}
259
260		/**
261	<	* Atomically updates and returns next seed for default constructor
261	>	* Returns a 57-bit mixed transformation of its argument.  See
262	>	* above for explanation.
263	>	*/
264	>	private static long mix57(long z) {
265	>	z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L;
266	>	z &= 0x01FFFFFFFFFFFFFFL;
267	>	z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
268	>	z &= 0x01FFFFFFFFFFFFFFL;
269	>	z ^= (z >>> 31);
270	>	return z;
271	>	}
272	>
273	>	/**
274	>	* 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.
296	>	*/
297	>	private long nextSeed() {
298	>	return seed = addGammaModGeorge(seed, gamma);
299	>	}
300	>
301	>	/**
302	>	* Atomically updates and returns next seed for default constructor.
303		*/
304		private static long nextDefaultSeed() {
305		long oldSeed, newSeed;
#	Line 280 | Line 310 | public class SplittableRandom {
310		return mix64(newSeed);
311		}
312
313	+	/**
314	+	* Returns an initial default seed.
315	+	*/
316	+	private static long getInitialDefaultSeed() {
317	+	byte[] seedBytes = java.security.SecureRandom.getSeed(8);
318	+	long s = (long)(seedBytes[0]) & 0xffL;
319	+	for (int i = 1; i < 8; ++i)
320	+	s = (s << 8) | ((long)(seedBytes[i]) & 0xffL);
321	+	return s;
322	+	}
323	+
324		/*
325		* Internal versions of nextX methods used by streams, as well as
326		* the public nextX(origin, bound) methods.  These exist mainly to
#	Line 311 | Line 352 | public class SplittableRandom {
352		* evenly divisible by the range. The loop rejects candidates
353		* computed from otherwise over-represented values.  The
354		* expected number of iterations under an ideal generator
355	<	* varies from 1 to 2, depending on the bound.
355	>	* varies from 1 to 2, depending on the bound. The loop itself
356	>	* takes an unlovable form. Because the first candidate is
357	>	* already available, we need a break-in-the-middle
358	>	* construction, which is concisely but cryptically performed
359	>	* within the while-condition of a body-less for loop.
360		*
361		* 4. Otherwise, the range cannot be represented as a positive
362	<	* long.  Repeatedly generate unbounded longs until obtaining
363	<	* a candidate meeting constraints (with an expected number of
364	<	* iterations of less than two).
362	>	* long.  The loop repeatedly generates unbounded longs until
363	>	* obtaining a candidate meeting constraints (with an expected
364	>	* number of iterations of less than two).
365		*/
366
367		long r = mix64(nextSeed());
368		if (origin < bound) {
369		long n = bound - origin, m = n - 1;
370	<	if ((n & m) == 0L) // power of two
370	>	if ((n & m) == 0L)  // power of two
371		r = (r & m) + origin;
372	<	else if (n > 0) { // reject over-represented candidates
372	>	else if (n > 0L) {  // reject over-represented candidates
373		for (long u = r >>> 1;            // ensure nonnegative
374	<	u + m - (r = u % n) < 0L;    // reject
374	>	u + m - (r = u % n) < 0L;    // rejection check
375		u = mix64(nextSeed()) >>> 1) // retry
376		;
377		r += origin;
378		}
379	<	else {             // range not representable as long
379	>	else {              // range not representable as long
380		while (r < origin || r >= bound)
381		r = mix64(nextSeed());
382		}
#	Line 351 | Line 396 | public class SplittableRandom {
396		int r = mix32(nextSeed());
397		if (origin < bound) {
398		int n = bound - origin, m = n - 1;
399	<	if ((n & m) == 0L)
399	>	if ((n & m) == 0)
400		r = (r & m) + origin;
401		else if (n > 0) {
402		for (int u = r >>> 1;
403	<	u + m - (r = u % n) < 0L;
403	>	u + m - (r = u % n) < 0;
404		u = mix32(nextSeed()) >>> 1)
405		;
406		r += origin;
#	Line 376 | Line 421 | public class SplittableRandom {
421		* @return a pseudorandom value
422		*/
423		final double internalNextDouble(double origin, double bound) {
424	<	long bits = (1023L << 52) | (nextLong() >>> 12);
380	<	double r = Double.longBitsToDouble(bits) - 1.0;
424	>	double r = (nextLong() >>> 11) * DOUBLE_UNIT;
425		if (origin < bound) {
426		r = r * (bound - origin) + origin;
427	<	if (r == bound) // correct for rounding
427	>	if (r >= bound) // correct for rounding
428		r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
429		}
430		return r;
#	Line 389 | Line 433 | public class SplittableRandom {
433		/* ---------------- public methods ---------------- */
434
435		/**
436	<	* Creates a new SplittableRandom instance using the given initial
437	<	* seed. Two SplittableRandom instances created with the same seed
438	<	* generate identical sequences of values.
436	>	* Creates a new SplittableRandom instance using the specified
437	>	* initial seed. SplittableRandom instances created with the same
438	>	* seed in the same program generate identical sequences of values.
439		*
440		* @param seed the initial seed
441		*/
442		public SplittableRandom(long seed) {
443	<	this(seed, 0);
443	>	this(seed, 0L);
444		}
445
446		/**
#	Line 430 | Line 474 | public class SplittableRandom {
474		/**
475		* Returns a pseudorandom {@code int} value.
476		*
477	<	* @return a pseudorandom value
477	>	* @return a pseudorandom {@code int} value
478		*/
479		public int nextInt() {
480		return mix32(nextSeed());
481		}
482
483		/**
484	<	* Returns a pseudorandom {@code int} value between 0 (inclusive)
484	>	* Returns a pseudorandom {@code int} value between zero (inclusive)
485		* and the specified bound (exclusive).
486		*
487		* @param bound the bound on the random number to be returned.  Must be
488		*        positive.
489	<	* @return a pseudorandom {@code int} value between {@code 0}
490	<	*         (inclusive) and the bound (exclusive).
491	<	* @exception IllegalArgumentException if the bound is not positive
489	>	* @return a pseudorandom {@code int} value between zero
490	>	*         (inclusive) and the bound (exclusive)
491	>	* @throws IllegalArgumentException if the bound is less than zero
492		*/
493		public int nextInt(int bound) {
494		if (bound <= 0)
#	Line 452 | Line 496 | public class SplittableRandom {
496		// Specialize internalNextInt for origin 0
497		int r = mix32(nextSeed());
498		int m = bound - 1;
499	<	if ((bound & m) == 0L) // power of two
499	>	if ((bound & m) == 0) // power of two
500		r &= m;
501		else { // reject over-represented candidates
502		for (int u = r >>> 1;
503	<	u + m - (r = u % bound) < 0L;
503	>	u + m - (r = u % bound) < 0;
504		u = mix32(nextSeed()) >>> 1)
505		;
506		}
#	Line 470 | Line 514 | public class SplittableRandom {
514		* @param origin the least value returned
515		* @param bound the upper bound (exclusive)
516		* @return a pseudorandom {@code int} value between the origin
517	<	*         (inclusive) and the bound (exclusive).
518	<	* @exception IllegalArgumentException if {@code origin} is greater than
517	>	*         (inclusive) and the bound (exclusive)
518	>	* @throws IllegalArgumentException if {@code origin} is greater than
519		*         or equal to {@code bound}
520		*/
521		public int nextInt(int origin, int bound) {
#	Line 483 | Line 527 | public class SplittableRandom {
527		/**
528		* Returns a pseudorandom {@code long} value.
529		*
530	<	* @return a pseudorandom value
530	>	* @return a pseudorandom {@code long} value
531		*/
532		public long nextLong() {
533		return mix64(nextSeed());
534		}
535
536		/**
537	<	* Returns a pseudorandom {@code long} value between 0 (inclusive)
537	>	* Returns a pseudorandom {@code long} value between zero (inclusive)
538		* and the specified bound (exclusive).
539		*
540		* @param bound the bound on the random number to be returned.  Must be
541		*        positive.
542	<	* @return a pseudorandom {@code long} value between {@code 0}
543	<	*         (inclusive) and the bound (exclusive).
544	<	* @exception IllegalArgumentException if the bound is not positive
542	>	* @return a pseudorandom {@code long} value between zero
543	>	*         (inclusive) and the bound (exclusive)
544	>	* @throws IllegalArgumentException if {@code bound} is less than zero
545		*/
546		public long nextLong(long bound) {
547		if (bound <= 0)
#	Line 523 | Line 567 | public class SplittableRandom {
567		* @param origin the least value returned
568		* @param bound the upper bound (exclusive)
569		* @return a pseudorandom {@code long} value between the origin
570	<	*         (inclusive) and the bound (exclusive).
571	<	* @exception IllegalArgumentException if {@code origin} is greater than
570	>	*         (inclusive) and the bound (exclusive)
571	>	* @throws IllegalArgumentException if {@code origin} is greater than
572		*         or equal to {@code bound}
573		*/
574		public long nextLong(long origin, long bound) {
#	Line 534 | Line 578 | public class SplittableRandom {
578		}
579
580		/**
581	<	* Returns a pseudorandom {@code double} value between {@code 0.0}
582	<	* (inclusive) and {@code 1.0} (exclusive).
581	>	* Returns a pseudorandom {@code double} value between zero
582	>	* (inclusive) and one (exclusive).
583		*
584	<	* @return a pseudorandom value between {@code 0.0}
585	<	* (inclusive) and {@code 1.0} (exclusive)
584	>	* @return a pseudorandom {@code double} value between zero
585	>	* (inclusive) and one (exclusive)
586		*/
587		public double nextDouble() {
588	<	long bits = (1023L << 52) | (nextLong() >>> 12);
545	<	return Double.longBitsToDouble(bits) - 1.0;
588	>	return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT;
589		}
590
591		/**
#	Line 551 | Line 594 | public class SplittableRandom {
594		*
595		* @param bound the bound on the random number to be returned.  Must be
596		*        positive.
597	<	* @return a pseudorandom {@code double} value between {@code 0.0}
598	<	*         (inclusive) and the bound (exclusive).
599	<	* @throws IllegalArgumentException if {@code bound} is not positive
597	>	* @return a pseudorandom {@code double} value between zero
598	>	*         (inclusive) and the bound (exclusive)
599	>	* @throws IllegalArgumentException if {@code bound} is less than zero
600		*/
601		public double nextDouble(double bound) {
602	<	if (bound <= 0.0)
602	>	if (!(bound > 0.0))
603		throw new IllegalArgumentException("bound must be positive");
604	<	double result = nextDouble() * bound;
604	>	double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound;
605		return (result < bound) ?  result : // correct for rounding
606		Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
607		}
608
609		/**
610	<	* Returns a pseudorandom {@code double} value between the given
610	>	* Returns a pseudorandom {@code double} value between the specified
611		* origin (inclusive) and bound (exclusive).
612		*
613		* @param origin the least value returned
614		* @param bound the upper bound
615		* @return a pseudorandom {@code double} value between the origin
616	<	*         (inclusive) and the bound (exclusive).
616	>	*         (inclusive) and the bound (exclusive)
617		* @throws IllegalArgumentException if {@code origin} is greater than
618		*         or equal to {@code bound}
619		*/
620		public double nextDouble(double origin, double bound) {
621	<	if (origin >= bound)
621	>	if (!(origin < bound))
622		throw new IllegalArgumentException("bound must be greater than origin");
623		return internalNextDouble(origin, bound);
624		}
625
626	+	/**
627	+	* Returns a pseudorandom {@code boolean} value.
628	+	*
629	+	* @return a pseudorandom {@code boolean} value
630	+	*/
631	+	public boolean nextBoolean() {
632	+	return mix32(nextSeed()) < 0;
633	+	}
634	+
635		// stream methods, coded in a way intended to better isolate for
636		// maintenance purposes the small differences across forms.
637
638		/**
639	<	* Returns a stream with the given {@code streamSize} number of
639	>	* Returns a stream producing the given {@code streamSize} number of
640		* pseudorandom {@code int} values.
641		*
642		* @param streamSize the number of values to generate
643		* @return a stream of pseudorandom {@code int} values
644		* @throws IllegalArgumentException if {@code streamSize} is
645	<	* less than zero
645	>	*         less than zero
646		*/
647		public IntStream ints(long streamSize) {
648		if (streamSize < 0L)
#	Line 603 | Line 655 | public class SplittableRandom {
655
656		/**
657		* Returns an effectively unlimited stream of pseudorandom {@code int}
658	<	* values
658	>	* values.
659		*
660		* @implNote This method is implemented to be equivalent to {@code
661		* ints(Long.MAX_VALUE)}.
#	Line 618 | Line 670 | public class SplittableRandom {
670		}
671
672		/**
673	<	* Returns a stream with the given {@code streamSize} number of
673	>	* Returns a stream producing the given {@code streamSize} number of
674		* pseudorandom {@code int} values, each conforming to the given
675		* origin and bound.
676		*
#	Line 626 | Line 678 | public class SplittableRandom {
678		* @param randomNumberOrigin the origin of each random value
679		* @param randomNumberBound the bound of each random value
680		* @return a stream of pseudorandom {@code int} values,
681	<	* each with the given origin and bound.
681	>	*         each with the given origin and bound
682		* @throws IllegalArgumentException if {@code streamSize} is
683	<	* less than zero.
632	<	* @throws IllegalArgumentException if {@code randomNumberOrigin}
683	>	*         less than zero, or {@code randomNumberOrigin}
684		*         is greater than or equal to {@code randomNumberBound}
685		*/
686		public IntStream ints(long streamSize, int randomNumberOrigin,
#	Line 654 | Line 705 | public class SplittableRandom {
705		* @param randomNumberOrigin the origin of each random value
706		* @param randomNumberBound the bound of each random value
707		* @return a stream of pseudorandom {@code int} values,
708	<	* each with the given origin and bound.
708	>	*         each with the given origin and bound
709		* @throws IllegalArgumentException if {@code randomNumberOrigin}
710		*         is greater than or equal to {@code randomNumberBound}
711		*/
#	Line 668 | Line 719 | public class SplittableRandom {
719		}
720
721		/**
722	<	* Returns a stream with the given {@code streamSize} number of
722	>	* Returns a stream producing the given {@code streamSize} number of
723		* pseudorandom {@code long} values.
724		*
725		* @param streamSize the number of values to generate
726	<	* @return a stream of {@code long} values
726	>	* @return a stream of pseudorandom {@code long} values
727		* @throws IllegalArgumentException if {@code streamSize} is
728	<	* less than zero
728	>	*         less than zero
729		*/
730		public LongStream longs(long streamSize) {
731		if (streamSize < 0L)
#	Line 702 | Line 753 | public class SplittableRandom {
753		}
754
755		/**
756	<	* Returns a stream with the given {@code streamSize} number of
756	>	* Returns a stream producing the given {@code streamSize} number of
757		* pseudorandom {@code long} values, each conforming to the
758		* given origin and bound.
759		*
#	Line 710 | Line 761 | public class SplittableRandom {
761		* @param randomNumberOrigin the origin of each random value
762		* @param randomNumberBound the bound of each random value
763		* @return a stream of pseudorandom {@code long} values,
764	<	* each with the given origin and bound.
764	>	*         each with the given origin and bound
765		* @throws IllegalArgumentException if {@code streamSize} is
766	<	* less than zero.
716	<	* @throws IllegalArgumentException if {@code randomNumberOrigin}
766	>	*         less than zero, or {@code randomNumberOrigin}
767		*         is greater than or equal to {@code randomNumberBound}
768		*/
769		public LongStream longs(long streamSize, long randomNumberOrigin,
#	Line 738 | Line 788 | public class SplittableRandom {
788		* @param randomNumberOrigin the origin of each random value
789		* @param randomNumberBound the bound of each random value
790		* @return a stream of pseudorandom {@code long} values,
791	<	* each with the given origin and bound.
791	>	*         each with the given origin and bound
792		* @throws IllegalArgumentException if {@code randomNumberOrigin}
793		*         is greater than or equal to {@code randomNumberBound}
794		*/
#	Line 752 | Line 802 | public class SplittableRandom {
802		}
803
804		/**
805	<	* Returns a stream with the given {@code streamSize} number of
806	<	* pseudorandom {@code double} values, each between {@code 0.0}
807	<	* (inclusive) and {@code 1.0} (exclusive).
805	>	* Returns a stream producing the given {@code streamSize} number of
806	>	* pseudorandom {@code double} values, each between zero
807	>	* (inclusive) and one (exclusive).
808		*
809		* @param streamSize the number of values to generate
810		* @return a stream of {@code double} values
811		* @throws IllegalArgumentException if {@code streamSize} is
812	<	* less than zero
812	>	*         less than zero
813		*/
814		public DoubleStream doubles(long streamSize) {
815		if (streamSize < 0L)
#	Line 772 | Line 822 | public class SplittableRandom {
822
823		/**
824		* Returns an effectively unlimited stream of pseudorandom {@code
825	<	* double} values, each between {@code 0.0} (inclusive) and {@code
826	<	* 1.0} (exclusive).
825	>	* double} values, each between zero (inclusive) and one
826	>	* (exclusive).
827		*
828		* @implNote This method is implemented to be equivalent to {@code
829		* doubles(Long.MAX_VALUE)}.
#	Line 788 | Line 838 | public class SplittableRandom {
838		}
839
840		/**
841	<	* Returns a stream with the given {@code streamSize} number of
841	>	* Returns a stream producing the given {@code streamSize} number of
842		* pseudorandom {@code double} values, each conforming to the
843		* given origin and bound.
844		*
#	Line 796 | Line 846 | public class SplittableRandom {
846		* @param randomNumberOrigin the origin of each random value
847		* @param randomNumberBound the bound of each random value
848		* @return a stream of pseudorandom {@code double} values,
849	<	* each with the given origin and bound.
849	>	* each with the given origin and bound
850		* @throws IllegalArgumentException if {@code streamSize} is
851	<	* less than zero.
851	>	* less than zero
852		* @throws IllegalArgumentException if {@code randomNumberOrigin}
853		*         is greater than or equal to {@code randomNumberBound}
854		*/
#	Line 806 | Line 856 | public class SplittableRandom {
856		double randomNumberBound) {
857		if (streamSize < 0L)
858		throw new IllegalArgumentException("negative Stream size");
859	<	if (randomNumberOrigin >= randomNumberBound)
859	>	if (!(randomNumberOrigin < randomNumberBound))
860		throw new IllegalArgumentException("bound must be greater than origin");
861		return StreamSupport.doubleStream
862		(new RandomDoublesSpliterator
#	Line 824 | Line 874 | public class SplittableRandom {
874		* @param randomNumberOrigin the origin of each random value
875		* @param randomNumberBound the bound of each random value
876		* @return a stream of pseudorandom {@code double} values,
877	<	* each with the given origin and bound.
877	>	* each with the given origin and bound
878		* @throws IllegalArgumentException if {@code randomNumberOrigin}
879		*         is greater than or equal to {@code randomNumberBound}
880		*/
881		public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
882	<	if (randomNumberOrigin >= randomNumberBound)
882	>	if (!(randomNumberOrigin < randomNumberBound))
883		throw new IllegalArgumentException("bound must be greater than origin");
884		return StreamSupport.doubleStream
885		(new RandomDoublesSpliterator
#	Line 839 | Line 889 | public class SplittableRandom {
889
890		/**
891		* Spliterator for int streams.  We multiplex the four int
892	<	* versions into one class by treating and bound < origin as
892	>	* versions into one class by treating a bound less than origin as
893		* unbounded, and also by treating "infinite" as equivalent to
894		* Long.MAX_VALUE. For splits, it uses the standard divide-by-two
895		* approach. The long and double versions of this class are
896		* identical except for types.
897		*/
898	<	static class RandomIntsSpliterator implements Spliterator.OfInt {
898	>	static final class RandomIntsSpliterator implements Spliterator.OfInt {
899		final SplittableRandom rng;
900		long index;
901		final long fence;
#	Line 869 | Line 919 | public class SplittableRandom {
919
920		public int characteristics() {
921		return (Spliterator.SIZED | Spliterator.SUBSIZED |
922	<	Spliterator.ORDERED | Spliterator.NONNULL |
873	<	Spliterator.IMMUTABLE);
922	>	Spliterator.NONNULL | Spliterator.IMMUTABLE);
923		}
924
925		public boolean tryAdvance(IntConsumer consumer) {
#	Line 900 | Line 949 | public class SplittableRandom {
949		/**
950		* Spliterator for long streams.
951		*/
952	<	static class RandomLongsSpliterator implements Spliterator.OfLong {
952	>	static final class RandomLongsSpliterator implements Spliterator.OfLong {
953		final SplittableRandom rng;
954		long index;
955		final long fence;
#	Line 924 | Line 973 | public class SplittableRandom {
973
974		public int characteristics() {
975		return (Spliterator.SIZED | Spliterator.SUBSIZED |
976	<	Spliterator.ORDERED | Spliterator.NONNULL |
928	<	Spliterator.IMMUTABLE);
976	>	Spliterator.NONNULL | Spliterator.IMMUTABLE);
977		}
978
979		public boolean tryAdvance(LongConsumer consumer) {
#	Line 956 | Line 1004 | public class SplittableRandom {
1004		/**
1005		* Spliterator for double streams.
1006		*/
1007	<	static class RandomDoublesSpliterator implements Spliterator.OfDouble {
1007	>	static final class RandomDoublesSpliterator implements Spliterator.OfDouble {
1008		final SplittableRandom rng;
1009		long index;
1010		final long fence;
#	Line 980 | Line 1028 | public class SplittableRandom {
1028
1029		public int characteristics() {
1030		return (Spliterator.SIZED | Spliterator.SUBSIZED |
1031	<	Spliterator.ORDERED | Spliterator.NONNULL |
984	<	Spliterator.IMMUTABLE);
1031	>	Spliterator.NONNULL | Spliterator.IMMUTABLE);
1032		}
1033
1034		public boolean tryAdvance(DoubleConsumer consumer) {
#	Line 1009 | Line 1056 | public class SplittableRandom {
1056		}
1057
1058		}
1012	–

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