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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 1.13 by dl, Thu Jul 25 13:19:09 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 "Mix01" 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 >>> 33);
266	>	z *= 0x7fb5d329728ea185L;
267	>	z &= 0x01FFFFFFFFFFFFFFL;
268	>	z ^= (z >>> 33);
269	>	z *= 0x81dadef4bc2dd44dL;
270	>	z &= 0x01FFFFFFFFFFFFFFL;
271	>	z ^= (z >>> 33);
272	>	return z;
273	>	}
274	>
275	>	/**
276	>	* Internal constructor used by all other constructors and by
277	>	* method split. Establishes the initial seed for this instance,
278	>	* and uses the given splitSeed to establish gamma, as well as the
279	>	* nextSplit to use by this instance. The loop to skip ineligible
280	>	* gammas very rarely iterates, and does so at most 13 times.
281	>	*/
282	>	private SplittableRandom(long seed, long splitSeed) {
283	>	this.seed = seed;
284	>	long s = splitSeed, g;
285	>	do { // ensure gamma >= 13, considered as an unsigned integer
286	>	s += GAMMA_GAMMA;
287	>	if (s >= GAMMA_PRIME)
288	>	s -= GAMMA_PRIME;
289	>	g = mix57(s);
290	>	} while (g < 13L);
291	>	this.gamma = g;
292	>	this.nextSplit = s;
293	>	}
294	>
295	>	/**
296	>	* Updates in-place and returns seed.
297	>	* See above for explanation.
298	>	*/
299	>	private long nextSeed() {
300	>	return seed = addGammaModGeorge(seed, gamma);
301	>	}
302	>
303	>	/**
304	>	* Atomically updates and returns next seed for default constructor.
305		*/
306		private static long nextDefaultSeed() {
307		long oldSeed, newSeed;
#	Line 280 | Line 312 | public class SplittableRandom {
312		return mix64(newSeed);
313		}
314
315	+	/**
316	+	* Returns an initial default seed.
317	+	*/
318	+	private static long getInitialDefaultSeed() {
319	+	byte[] seedBytes = java.security.SecureRandom.getSeed(8);
320	+	long s = (long)(seedBytes[0]) & 0xffL;
321	+	for (int i = 1; i < 8; ++i)
322	+	s = (s << 8) | ((long)(seedBytes[i]) & 0xffL);
323	+	return s;
324	+	}
325	+
326		/*
327		* Internal versions of nextX methods used by streams, as well as
328		* the public nextX(origin, bound) methods.  These exist mainly to
#	Line 311 | Line 354 | public class SplittableRandom {
354		* evenly divisible by the range. The loop rejects candidates
355		* computed from otherwise over-represented values.  The
356		* expected number of iterations under an ideal generator
357	<	* varies from 1 to 2, depending on the bound.
357	>	* varies from 1 to 2, depending on the bound. The loop itself
358	>	* takes an unlovable form. Because the first candidate is
359	>	* already available, we need a break-in-the-middle
360	>	* construction, which is concisely but cryptically performed
361	>	* within the while-condition of a body-less for loop.
362		*
363		* 4. Otherwise, the range cannot be represented as a positive
364	<	* long.  Repeatedly generate unbounded longs until obtaining
365	<	* a candidate meeting constraints (with an expected number of
366	<	* iterations of less than two).
364	>	* long.  The loop repeatedly generates unbounded longs until
365	>	* obtaining a candidate meeting constraints (with an expected
366	>	* number of iterations of less than two).
367		*/
368
369		long r = mix64(nextSeed());
370		if (origin < bound) {
371		long n = bound - origin, m = n - 1;
372	<	if ((n & m) == 0L) // power of two
372	>	if ((n & m) == 0L)  // power of two
373		r = (r & m) + origin;
374	<	else if (n > 0) { // reject over-represented candidates
374	>	else if (n > 0L) {  // reject over-represented candidates
375		for (long u = r >>> 1;            // ensure nonnegative
376	<	u + m - (r = u % n) < 0L;    // reject
376	>	u + m - (r = u % n) < 0L;    // rejection check
377		u = mix64(nextSeed()) >>> 1) // retry
378		;
379		r += origin;
380		}
381	<	else {             // range not representable as long
381	>	else {              // range not representable as long
382		while (r < origin || r >= bound)
383		r = mix64(nextSeed());
384		}
#	Line 351 | Line 398 | public class SplittableRandom {
398		int r = mix32(nextSeed());
399		if (origin < bound) {
400		int n = bound - origin, m = n - 1;
401	<	if ((n & m) == 0L)
401	>	if ((n & m) == 0)
402		r = (r & m) + origin;
403		else if (n > 0) {
404		for (int u = r >>> 1;
405	<	u + m - (r = u % n) < 0L;
405	>	u + m - (r = u % n) < 0;
406		u = mix32(nextSeed()) >>> 1)
407		;
408		r += origin;
#	Line 376 | Line 423 | public class SplittableRandom {
423		* @return a pseudorandom value
424		*/
425		final double internalNextDouble(double origin, double bound) {
426	<	long bits = (1023L << 52) | (nextLong() >>> 12);
380	<	double r = Double.longBitsToDouble(bits) - 1.0;
426	>	double r = (nextLong() >>> 11) * DOUBLE_UNIT;
427		if (origin < bound) {
428		r = r * (bound - origin) + origin;
429	<	if (r == bound) // correct for rounding
429	>	if (r >= bound) // correct for rounding
430		r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
431		}
432		return r;
#	Line 389 | Line 435 | public class SplittableRandom {
435		/* ---------------- public methods ---------------- */
436
437		/**
438	<	* Creates a new SplittableRandom instance using the given initial
439	<	* seed. Two SplittableRandom instances created with the same seed
440	<	* generate identical sequences of values.
438	>	* Creates a new SplittableRandom instance using the specified
439	>	* initial seed. SplittableRandom instances created with the same
440	>	* seed in the same program generate identical sequences of values.
441		*
442		* @param seed the initial seed
443		*/
444		public SplittableRandom(long seed) {
445	<	this(seed, 0);
445	>	this(seed, 0L);
446		}
447
448		/**
#	Line 430 | Line 476 | public class SplittableRandom {
476		/**
477		* Returns a pseudorandom {@code int} value.
478		*
479	<	* @return a pseudorandom value
479	>	* @return a pseudorandom {@code int} value
480		*/
481		public int nextInt() {
482		return mix32(nextSeed());
483		}
484
485		/**
486	<	* Returns a pseudorandom {@code int} value between 0 (inclusive)
486	>	* Returns a pseudorandom {@code int} value between zero (inclusive)
487		* and the specified bound (exclusive).
488		*
489		* @param bound the bound on the random number to be returned.  Must be
490		*        positive.
491	<	* @return a pseudorandom {@code int} value between {@code 0}
492	<	*         (inclusive) and the bound (exclusive).
493	<	* @exception IllegalArgumentException if the bound is not positive
491	>	* @return a pseudorandom {@code int} value between zero
492	>	*         (inclusive) and the bound (exclusive)
493	>	* @throws IllegalArgumentException if the bound is less than zero
494		*/
495		public int nextInt(int bound) {
496		if (bound <= 0)
#	Line 452 | Line 498 | public class SplittableRandom {
498		// Specialize internalNextInt for origin 0
499		int r = mix32(nextSeed());
500		int m = bound - 1;
501	<	if ((bound & m) == 0L) // power of two
501	>	if ((bound & m) == 0) // power of two
502		r &= m;
503		else { // reject over-represented candidates
504		for (int u = r >>> 1;
505	<	u + m - (r = u % bound) < 0L;
505	>	u + m - (r = u % bound) < 0;
506		u = mix32(nextSeed()) >>> 1)
507		;
508		}
#	Line 470 | Line 516 | public class SplittableRandom {
516		* @param origin the least value returned
517		* @param bound the upper bound (exclusive)
518		* @return a pseudorandom {@code int} value between the origin
519	<	*         (inclusive) and the bound (exclusive).
520	<	* @exception IllegalArgumentException if {@code origin} is greater than
519	>	*         (inclusive) and the bound (exclusive)
520	>	* @throws IllegalArgumentException if {@code origin} is greater than
521		*         or equal to {@code bound}
522		*/
523		public int nextInt(int origin, int bound) {
#	Line 483 | Line 529 | public class SplittableRandom {
529		/**
530		* Returns a pseudorandom {@code long} value.
531		*
532	<	* @return a pseudorandom value
532	>	* @return a pseudorandom {@code long} value
533		*/
534		public long nextLong() {
535		return mix64(nextSeed());
536		}
537
538		/**
539	<	* Returns a pseudorandom {@code long} value between 0 (inclusive)
539	>	* Returns a pseudorandom {@code long} value between zero (inclusive)
540		* and the specified bound (exclusive).
541		*
542		* @param bound the bound on the random number to be returned.  Must be
543		*        positive.
544	<	* @return a pseudorandom {@code long} value between {@code 0}
545	<	*         (inclusive) and the bound (exclusive).
546	<	* @exception IllegalArgumentException if the bound is not positive
544	>	* @return a pseudorandom {@code long} value between zero
545	>	*         (inclusive) and the bound (exclusive)
546	>	* @throws IllegalArgumentException if {@code bound} is less than zero
547		*/
548		public long nextLong(long bound) {
549		if (bound <= 0)
#	Line 523 | Line 569 | public class SplittableRandom {
569		* @param origin the least value returned
570		* @param bound the upper bound (exclusive)
571		* @return a pseudorandom {@code long} value between the origin
572	<	*         (inclusive) and the bound (exclusive).
573	<	* @exception IllegalArgumentException if {@code origin} is greater than
572	>	*         (inclusive) and the bound (exclusive)
573	>	* @throws IllegalArgumentException if {@code origin} is greater than
574		*         or equal to {@code bound}
575		*/
576		public long nextLong(long origin, long bound) {
#	Line 534 | Line 580 | public class SplittableRandom {
580		}
581
582		/**
583	<	* Returns a pseudorandom {@code double} value between {@code 0.0}
584	<	* (inclusive) and {@code 1.0} (exclusive).
583	>	* Returns a pseudorandom {@code double} value between zero
584	>	* (inclusive) and one (exclusive).
585		*
586	<	* @return a pseudorandom value between {@code 0.0}
587	<	* (inclusive) and {@code 1.0} (exclusive)
586	>	* @return a pseudorandom {@code double} value between zero
587	>	* (inclusive) and one (exclusive)
588		*/
589		public double nextDouble() {
590	<	long bits = (1023L << 52) | (nextLong() >>> 12);
545	<	return Double.longBitsToDouble(bits) - 1.0;
590	>	return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT;
591		}
592
593		/**
#	Line 551 | Line 596 | public class SplittableRandom {
596		*
597		* @param bound the bound on the random number to be returned.  Must be
598		*        positive.
599	<	* @return a pseudorandom {@code double} value between {@code 0.0}
600	<	*         (inclusive) and the bound (exclusive).
601	<	* @throws IllegalArgumentException if {@code bound} is not positive
599	>	* @return a pseudorandom {@code double} value between zero
600	>	*         (inclusive) and the bound (exclusive)
601	>	* @throws IllegalArgumentException if {@code bound} is less than zero
602		*/
603		public double nextDouble(double bound) {
604	<	if (bound <= 0.0)
604	>	if (!(bound > 0.0))
605		throw new IllegalArgumentException("bound must be positive");
606	<	double result = nextDouble() * bound;
606	>	double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound;
607		return (result < bound) ?  result : // correct for rounding
608		Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
609		}
610
611		/**
612	<	* Returns a pseudorandom {@code double} value between the given
612	>	* Returns a pseudorandom {@code double} value between the specified
613		* origin (inclusive) and bound (exclusive).
614		*
615		* @param origin the least value returned
616		* @param bound the upper bound
617		* @return a pseudorandom {@code double} value between the origin
618	<	*         (inclusive) and the bound (exclusive).
618	>	*         (inclusive) and the bound (exclusive)
619		* @throws IllegalArgumentException if {@code origin} is greater than
620		*         or equal to {@code bound}
621		*/
622		public double nextDouble(double origin, double bound) {
623	<	if (origin >= bound)
623	>	if (!(origin < bound))
624		throw new IllegalArgumentException("bound must be greater than origin");
625		return internalNextDouble(origin, bound);
626		}
627
628	+	/**
629	+	* Returns a pseudorandom {@code boolean} value.
630	+	*
631	+	* @return a pseudorandom {@code boolean} value
632	+	*/
633	+	public boolean nextBoolean() {
634	+	return mix32(nextSeed()) < 0;
635	+	}
636	+
637		// stream methods, coded in a way intended to better isolate for
638		// maintenance purposes the small differences across forms.
639
640		/**
641	<	* Returns a stream with the given {@code streamSize} number of
641	>	* Returns a stream producing the given {@code streamSize} number of
642		* pseudorandom {@code int} values.
643		*
644		* @param streamSize the number of values to generate
645		* @return a stream of pseudorandom {@code int} values
646		* @throws IllegalArgumentException if {@code streamSize} is
647	<	* less than zero
647	>	*         less than zero
648		*/
649		public IntStream ints(long streamSize) {
650		if (streamSize < 0L)
#	Line 603 | Line 657 | public class SplittableRandom {
657
658		/**
659		* Returns an effectively unlimited stream of pseudorandom {@code int}
660	<	* values
660	>	* values.
661		*
662		* @implNote This method is implemented to be equivalent to {@code
663		* ints(Long.MAX_VALUE)}.
#	Line 618 | Line 672 | public class SplittableRandom {
672		}
673
674		/**
675	<	* Returns a stream with the given {@code streamSize} number of
675	>	* Returns a stream producing the given {@code streamSize} number of
676		* pseudorandom {@code int} values, each conforming to the given
677		* origin and bound.
678		*
#	Line 626 | Line 680 | public class SplittableRandom {
680		* @param randomNumberOrigin the origin of each random value
681		* @param randomNumberBound the bound of each random value
682		* @return a stream of pseudorandom {@code int} values,
683	<	* each with the given origin and bound.
683	>	*         each with the given origin and bound
684		* @throws IllegalArgumentException if {@code streamSize} is
685	<	* less than zero.
632	<	* @throws IllegalArgumentException if {@code randomNumberOrigin}
685	>	*         less than zero, or {@code randomNumberOrigin}
686		*         is greater than or equal to {@code randomNumberBound}
687		*/
688		public IntStream ints(long streamSize, int randomNumberOrigin,
#	Line 654 | Line 707 | public class SplittableRandom {
707		* @param randomNumberOrigin the origin of each random value
708		* @param randomNumberBound the bound of each random value
709		* @return a stream of pseudorandom {@code int} values,
710	<	* each with the given origin and bound.
710	>	*         each with the given origin and bound
711		* @throws IllegalArgumentException if {@code randomNumberOrigin}
712		*         is greater than or equal to {@code randomNumberBound}
713		*/
#	Line 668 | Line 721 | public class SplittableRandom {
721		}
722
723		/**
724	<	* Returns a stream with the given {@code streamSize} number of
724	>	* Returns a stream producing the given {@code streamSize} number of
725		* pseudorandom {@code long} values.
726		*
727		* @param streamSize the number of values to generate
728	<	* @return a stream of {@code long} values
728	>	* @return a stream of pseudorandom {@code long} values
729		* @throws IllegalArgumentException if {@code streamSize} is
730	<	* less than zero
730	>	*         less than zero
731		*/
732		public LongStream longs(long streamSize) {
733		if (streamSize < 0L)
#	Line 702 | Line 755 | public class SplittableRandom {
755		}
756
757		/**
758	<	* Returns a stream with the given {@code streamSize} number of
758	>	* Returns a stream producing the given {@code streamSize} number of
759		* pseudorandom {@code long} values, each conforming to the
760		* given origin and bound.
761		*
#	Line 710 | Line 763 | public class SplittableRandom {
763		* @param randomNumberOrigin the origin of each random value
764		* @param randomNumberBound the bound of each random value
765		* @return a stream of pseudorandom {@code long} values,
766	<	* each with the given origin and bound.
766	>	*         each with the given origin and bound
767		* @throws IllegalArgumentException if {@code streamSize} is
768	<	* less than zero.
716	<	* @throws IllegalArgumentException if {@code randomNumberOrigin}
768	>	*         less than zero, or {@code randomNumberOrigin}
769		*         is greater than or equal to {@code randomNumberBound}
770		*/
771		public LongStream longs(long streamSize, long randomNumberOrigin,
#	Line 738 | Line 790 | public class SplittableRandom {
790		* @param randomNumberOrigin the origin of each random value
791		* @param randomNumberBound the bound of each random value
792		* @return a stream of pseudorandom {@code long} values,
793	<	* each with the given origin and bound.
793	>	*         each with the given origin and bound
794		* @throws IllegalArgumentException if {@code randomNumberOrigin}
795		*         is greater than or equal to {@code randomNumberBound}
796		*/
#	Line 752 | Line 804 | public class SplittableRandom {
804		}
805
806		/**
807	<	* Returns a stream with the given {@code streamSize} number of
808	<	* pseudorandom {@code double} values, each between {@code 0.0}
809	<	* (inclusive) and {@code 1.0} (exclusive).
807	>	* Returns a stream producing the given {@code streamSize} number of
808	>	* pseudorandom {@code double} values, each between zero
809	>	* (inclusive) and one (exclusive).
810		*
811		* @param streamSize the number of values to generate
812		* @return a stream of {@code double} values
813		* @throws IllegalArgumentException if {@code streamSize} is
814	<	* less than zero
814	>	*         less than zero
815		*/
816		public DoubleStream doubles(long streamSize) {
817		if (streamSize < 0L)
#	Line 772 | Line 824 | public class SplittableRandom {
824
825		/**
826		* Returns an effectively unlimited stream of pseudorandom {@code
827	<	* double} values, each between {@code 0.0} (inclusive) and {@code
828	<	* 1.0} (exclusive).
827	>	* double} values, each between zero (inclusive) and one
828	>	* (exclusive).
829		*
830		* @implNote This method is implemented to be equivalent to {@code
831		* doubles(Long.MAX_VALUE)}.
#	Line 788 | Line 840 | public class SplittableRandom {
840		}
841
842		/**
843	<	* Returns a stream with the given {@code streamSize} number of
843	>	* Returns a stream producing the given {@code streamSize} number of
844		* pseudorandom {@code double} values, each conforming to the
845		* given origin and bound.
846		*
#	Line 796 | Line 848 | public class SplittableRandom {
848		* @param randomNumberOrigin the origin of each random value
849		* @param randomNumberBound the bound of each random value
850		* @return a stream of pseudorandom {@code double} values,
851	<	* each with the given origin and bound.
851	>	* each with the given origin and bound
852		* @throws IllegalArgumentException if {@code streamSize} is
853	<	* less than zero.
853	>	* less than zero
854		* @throws IllegalArgumentException if {@code randomNumberOrigin}
855		*         is greater than or equal to {@code randomNumberBound}
856		*/
#	Line 806 | Line 858 | public class SplittableRandom {
858		double randomNumberBound) {
859		if (streamSize < 0L)
860		throw new IllegalArgumentException("negative Stream size");
861	<	if (randomNumberOrigin >= randomNumberBound)
861	>	if (!(randomNumberOrigin < randomNumberBound))
862		throw new IllegalArgumentException("bound must be greater than origin");
863		return StreamSupport.doubleStream
864		(new RandomDoublesSpliterator
#	Line 824 | Line 876 | public class SplittableRandom {
876		* @param randomNumberOrigin the origin of each random value
877		* @param randomNumberBound the bound of each random value
878		* @return a stream of pseudorandom {@code double} values,
879	<	* each with the given origin and bound.
879	>	* each with the given origin and bound
880		* @throws IllegalArgumentException if {@code randomNumberOrigin}
881		*         is greater than or equal to {@code randomNumberBound}
882		*/
883		public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
884	<	if (randomNumberOrigin >= randomNumberBound)
884	>	if (!(randomNumberOrigin < randomNumberBound))
885		throw new IllegalArgumentException("bound must be greater than origin");
886		return StreamSupport.doubleStream
887		(new RandomDoublesSpliterator
#	Line 839 | Line 891 | public class SplittableRandom {
891
892		/**
893		* Spliterator for int streams.  We multiplex the four int
894	<	* versions into one class by treating and bound < origin as
894	>	* versions into one class by treating a bound less than origin as
895		* unbounded, and also by treating "infinite" as equivalent to
896		* Long.MAX_VALUE. For splits, it uses the standard divide-by-two
897		* approach. The long and double versions of this class are
898		* identical except for types.
899		*/
900	<	static class RandomIntsSpliterator implements Spliterator.OfInt {
900	>	static final class RandomIntsSpliterator implements Spliterator.OfInt {
901		final SplittableRandom rng;
902		long index;
903		final long fence;
#	Line 869 | Line 921 | public class SplittableRandom {
921
922		public int characteristics() {
923		return (Spliterator.SIZED | Spliterator.SUBSIZED |
924	<	Spliterator.ORDERED | Spliterator.NONNULL |
873	<	Spliterator.IMMUTABLE);
924	>	Spliterator.NONNULL | Spliterator.IMMUTABLE);
925		}
926
927		public boolean tryAdvance(IntConsumer consumer) {
#	Line 900 | Line 951 | public class SplittableRandom {
951		/**
952		* Spliterator for long streams.
953		*/
954	<	static class RandomLongsSpliterator implements Spliterator.OfLong {
954	>	static final class RandomLongsSpliterator implements Spliterator.OfLong {
955		final SplittableRandom rng;
956		long index;
957		final long fence;
#	Line 924 | Line 975 | public class SplittableRandom {
975
976		public int characteristics() {
977		return (Spliterator.SIZED | Spliterator.SUBSIZED |
978	<	Spliterator.ORDERED | Spliterator.NONNULL |
928	<	Spliterator.IMMUTABLE);
978	>	Spliterator.NONNULL | Spliterator.IMMUTABLE);
979		}
980
981		public boolean tryAdvance(LongConsumer consumer) {
#	Line 956 | Line 1006 | public class SplittableRandom {
1006		/**
1007		* Spliterator for double streams.
1008		*/
1009	<	static class RandomDoublesSpliterator implements Spliterator.OfDouble {
1009	>	static final class RandomDoublesSpliterator implements Spliterator.OfDouble {
1010		final SplittableRandom rng;
1011		long index;
1012		final long fence;
#	Line 980 | Line 1030 | public class SplittableRandom {
1030
1031		public int characteristics() {
1032		return (Spliterator.SIZED | Spliterator.SUBSIZED |
1033	<	Spliterator.ORDERED | Spliterator.NONNULL |
984	<	Spliterator.IMMUTABLE);
1033	>	Spliterator.NONNULL | Spliterator.IMMUTABLE);
1034		}
1035
1036		public boolean tryAdvance(DoubleConsumer consumer) {
#	Line 1009 | Line 1058 | public class SplittableRandom {
1058		}
1059
1060		}
1012	–

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