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Comparing jsr166/src/main/java/util/SplittableRandom.java (file contents):
Revision 1.14 by dl, Mon Aug 5 13:58:02 2013 UTC vs.
Revision 1.31 by jsr166, Fri Feb 19 03:39:15 2016 UTC

#	Line 25 | Line 25
25
26		package java.util;
27
28	–	import java.security.SecureRandom;
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 {
85	<
86	<	/*
87	<	* File organization: First the non-public methods that constitute
88	<	* the main algorithm, then the main public methods, followed by
89	<	* some custom spliterator classes needed for stream methods.
90	<	*
91	<	* Credits: Primary algorithm and code by Guy Steele.  Stream
92	<	* support methods by Doug Lea.  Documentation jointly produced
93	<	* with additional help from Brian Goetz.
94	<	*/
89	>	public final class SplittableRandom {
90
91		/*
92		* Implementation Overview.
#	Line 99 | Line 94 | public class SplittableRandom {
94		* This algorithm was inspired by the "DotMix" algorithm by
95		* Leiserson, Schardl, and Sukha "Deterministic Parallel
96		* Random-Number Generation for Dynamic-Multithreading Platforms",
97	<	* PPoPP 2012, but improves and extends it in several ways.
97	>	* PPoPP 2012, as well as those in "Parallel random numbers: as
98	>	* easy as 1, 2, 3" by Salmon, Morae, Dror, and Shaw, SC 2011.  It
99	>	* differs mainly in simplifying and cheapening operations.
100	>	*
101	>	* The primary update step (method nextSeed()) is to add a
102	>	* constant ("gamma") to the current (64 bit) seed, forming a
103	>	* simple sequence.  The seed and the gamma values for any two
104	>	* SplittableRandom instances are highly likely to be different.
105	>	*
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 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 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.
131	>	*
132	>	* The resulting generator thus transforms a sequence in which
133	>	* (typically) many bits change on each step, with an inexpensive
134	>	* mixer with good (but less than cryptographically secure)
135	>	* avalanching.
136	>	*
137	>	* The default (no-argument) constructor, in essence, invokes
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
149	>	* carrying around twice the state add more overhead than appears
150	>	* warranted for current usages.
151		*
152	<	* The primary update step (see method nextSeed()) is simply to
153	<	* add a constant ("gamma") to the current seed, modulo a prime
154	<	* ("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
113	<	* than can fit in a long ensures that all possible long values
114	<	* can occur, plus 13 others that just get skipped over when they
115	<	* are encountered; see method addGammaModGeorge. For this to
116	<	* work, initial gamma values must be at least 13.
117	<	*
118	<	* The mix64 bit-mixing function called by nextLong and other
119	<	* methods computes the same value as the "64-bit finalizer"
120	<	* function in Austin Appleby's MurmurHash3 algorithm.  See
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."
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
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
148	<	* equivalent of a split of a statically constructed
149	<	* SplittableRandom. Unlike other cases, this split must be
150	<	* performed in a thread-safe manner. We use
151	<	* AtomicLong.compareAndSet as the (typically) most efficient
152	<	* mechanism. To bootstrap, we start off using a SecureRandom
153	<	* initial default seed, and update using a fixed
154	<	* DEFAULT_SEED_GAMMA. The default constructor uses GAMMA_GAMMA,
155	<	* not 0, for its splitSeed argument (addGammaModGeorge(0,
156	<	* GAMMA_GAMMA) == GAMMA_GAMMA) to reflect that each is split from
157	<	* this root generator, even though the root is not explicitly
158	<	* represented as a SplittableRandom.
159	<	*/
160	<
161	<	/**
162	<	* The prime modulus for gamma values.
163	<	*/
164	<	private static final long GAMMA_PRIME = (1L << 57) - 13L;
165	<
166	<	/**
167	<	* The value for producing new gamma values. Must be greater or
168	<	* equal to 13 and less than GAMMA_PRIME. Otherwise, the value is
169	<	* arbitrary subject to validation of the resulting statistical
170	<	* quality of splits.
171	<	*/
172	<	private static final long GAMMA_GAMMA = 0x00aae38294f712aabL;
173	<
174	<	/**
175	<	* The seed update value for default constructors.  Must be
176	<	* greater or equal to 13. Otherwise, the value is arbitrary
177	<	* subject to quality checks.
152	>	* File organization: First the non-public methods that constitute
153	>	* the main algorithm, then the main public methods, followed by
154	>	* some custom spliterator classes needed for stream methods.
155		*/
179	–	private static final long DEFAULT_SEED_GAMMA = 0x9e3779b97f4a7c15L;
156
157		/**
158	<	* The value 13 with 64bit sign bit set. Used in the signed
159	<	* comparison in addGammaModGeorge.
158	>	* The golden ratio scaled to 64bits, used as the initial gamma
159	>	* value for (unsplit) SplittableRandoms.
160		*/
161	<	private static final long BOTTOM13 = 0x800000000000000DL;
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);
192	<
193	<	/**
194	<	* The next seed for default constructors.
195	<	*/
196	<	private static final AtomicLong defaultSeedGenerator =
197	<	new AtomicLong(getInitialDefaultSeed());
167	>	private static final double DOUBLE_UNIT = 0x1.0p-53; // 1.0 / (1L << 53);
168
169		/**
170	<	* The seed, updated only via method nextSeed.
170	>	* The seed. Updated only via method nextSeed.
171		*/
172		private long seed;
173
174		/**
175	<	* The constant value added to seed (mod George) on each update.
175	>	* The step value.
176		*/
177		private final long gamma;
178
179		/**
180	<	* The next seed to use for splits. Propagated using
211	<	* addGammaModGeorge across instances.
180	>	* Internal constructor used by all others except default constructor.
181		*/
182	<	private final long nextSplit;
183	<
184	<	/**
216	<	* Adds the given gamma value, g, to the given seed value s, mod
217	<	* George (2^64+13). We regard s and g as unsigned values
218	<	* (ranging from 0 to 2^64-1). We add g to s either once or twice
219	<	* (mod George) as necessary to produce an (unsigned) result less
220	<	* than 2^64.  We require that g must be at least 13. This
221	<	* guarantees that if (s+g) mod George >= 2^64 then (s+g+g) mod
222	<	* George < 2^64; thus we need only a conditional, not a loop,
223	<	* to be sure of getting a representable value.
224	<	*
225	<	* Because Java comparison operators are signed, we implement this
226	<	* by conceptually offsetting seed values downwards by 2^63, so
227	<	* 0..13 is represented as Long.MIN_VALUE..BOTTOM13.
228	<	*
229	<	* @param s a seed value, viewed as a signed long
230	<	* @param g a gamma value, 13 <= g (as unsigned)
231	<	*/
232	<	private static long addGammaModGeorge(long s, long g) {
233	<	long p = s + g;
234	<	return (p >= s) ? p : ((p >= BOTTOM13) ? p  : p + g) - 13L;
182	>	private SplittableRandom(long seed, long gamma) {
183	>	this.seed = seed;
184	>	this.gamma = gamma;
185		}
186
187		/**
188	<	* Returns a bit-mixed transformation of its argument.
239	<	* See above for explanation.
188	>	* Computes Stafford variant 13 of 64bit mix function.
189		*/
190		private static long mix64(long z) {
191	<	z ^= (z >>> 33);
192	<	z *= 0xff51afd7ed558ccdL;
193	<	z ^= (z >>> 33);
245	<	z *= 0xc4ceb9fe1a85ec53L;
246	<	z ^= (z >>> 33);
247	<	return z;
191	>	z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L;
192	>	z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
193	>	return z ^ (z >>> 31);
194		}
195
196		/**
197	<	* Returns a bit-mixed int transformation of its argument.
252	<	* See above for explanation.
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 >>> 33);
201	<	z *= 0xc4ceb9fe1a85ec53L;
257	<	return (int)(z >>> 32);
200	>	z = (z ^ (z >>> 33)) * 0x62a9d9ed799705f5L;
201	>	return (int)(((z ^ (z >>> 28)) * 0xcb24d0a5c88c35b3L) >>> 32);
202		}
203
204		/**
205	<	* Returns a 57-bit mixed transformation of its argument.  See
262	<	* above for explanation.
205	>	* Returns the gamma value to use for a new split instance.
206		*/
207	<	private static long mix57(long z) {
208	<	z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L;
209	<	z &= 0x01FFFFFFFFFFFFFFL;
210	<	z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
211	<	z &= 0x01FFFFFFFFFFFFFFL;
212	<	z ^= (z >>> 31);
270	<	return 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		/**
216	<	* 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.
216	>	* Adds gamma to seed.
217		*/
218		private long nextSeed() {
219	<	return seed = addGammaModGeorge(seed, gamma);
219	>	return seed += gamma;
220		}
221
222		/**
223	<	* Atomically updates and returns next seed for default constructor.
223	>	* The seed generator for default constructors.
224		*/
225	<	private static long nextDefaultSeed() {
305	<	long oldSeed, newSeed;
306	<	do {
307	<	oldSeed = defaultSeedGenerator.get();
308	<	newSeed = addGammaModGeorge(oldSeed, DEFAULT_SEED_GAMMA);
309	<	} while (!defaultSeedGenerator.compareAndSet(oldSeed, newSeed));
310	<	return mix64(newSeed);
311	<	}
225	>	private static final AtomicLong defaultGen = new AtomicLong(initialSeed());
226
227	<	/**
228	<	* Returns an initial default seed.
229	<	*/
230	<	private static long getInitialDefaultSeed() {
231	<	byte[] seedBytes = java.security.SecureRandom.getSeed(8);
232	<	long s = (long)(seedBytes[0]) & 0xffL;
233	<	for (int i = 1; i < 8; ++i)
234	<	s = (s << 8) | ((long)(seedBytes[i]) & 0xffL);
235	<	return s;
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 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
250		* the public nextX(origin, bound) methods.  These exist mainly to
#	Line 440 | Line 364 | public class SplittableRandom {
364		* @param seed the initial seed
365		*/
366		public SplittableRandom(long seed) {
367	<	this(seed, 0L);
367	>	this(seed, GOLDEN_GAMMA);
368		}
369
370		/**
#	Line 449 | 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() {
377	<	this(nextDefaultSeed(), GAMMA_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 468 | Line 394 | public class SplittableRandom {
394		* @return the new SplittableRandom instance
395		*/
396		public SplittableRandom split() {
397	<	return new SplittableRandom(nextSeed(), nextSplit);
397	>	return new SplittableRandom(nextLong(), mixGamma(nextSeed()));
398		}
399
400		/**
#	Line 484 | 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
488	<	*        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("bound must be positive");
420	>	throw new IllegalArgumentException(BAD_BOUND);
421		// Specialize internalNextInt for origin 0
422		int r = mix32(nextSeed());
423		int m = bound - 1;
#	Line 520 | Line 445 | public class SplittableRandom {
445		*/
446		public int nextInt(int origin, int bound) {
447		if (origin >= bound)
448	<	throw new IllegalArgumentException("bound must be greater than origin");
448	>	throw new IllegalArgumentException(BAD_RANGE);
449		return internalNextInt(origin, bound);
450		}
451
#	Line 537 | 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
541	<	*        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("bound must be positive");
472	>	throw new IllegalArgumentException(BAD_BOUND);
473		// Specialize internalNextLong for origin 0
474		long r = mix64(nextSeed());
475		long m = bound - 1;
#	Line 573 | Line 497 | public class SplittableRandom {
497		*/
498		public long nextLong(long origin, long bound) {
499		if (origin >= bound)
500	<	throw new IllegalArgumentException("bound must be greater than origin");
500	>	throw new IllegalArgumentException(BAD_RANGE);
501		return internalNextLong(origin, bound);
502		}
503
#	Line 582 | 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 592 | 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
596	<	*        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("bound must be positive");
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 611 | 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 619 | Line 542 | public class SplittableRandom {
542		*/
543		public double nextDouble(double origin, double bound) {
544		if (!(origin < bound))
545	<	throw new IllegalArgumentException("bound must be greater than origin");
545	>	throw new IllegalArgumentException(BAD_RANGE);
546		return internalNextDouble(origin, bound);
547		}
548
#	Line 636 | 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 646 | Line 570 | public class SplittableRandom {
570		*/
571		public IntStream ints(long streamSize) {
572		if (streamSize < 0L)
573	<	throw new IllegalArgumentException("negative Stream size");
573	>	throw new IllegalArgumentException(BAD_SIZE);
574		return StreamSupport.intStream
575		(new RandomIntsSpliterator
576		(this, 0L, streamSize, Integer.MAX_VALUE, 0),
#	Line 655 | 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 670 | 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 686 | Line 611 | public class SplittableRandom {
611		public IntStream ints(long streamSize, int randomNumberOrigin,
612		int randomNumberBound) {
613		if (streamSize < 0L)
614	<	throw new IllegalArgumentException("negative Stream size");
614	>	throw new IllegalArgumentException(BAD_SIZE);
615		if (randomNumberOrigin >= randomNumberBound)
616	<	throw new IllegalArgumentException("bound must be greater than origin");
616	>	throw new IllegalArgumentException(BAD_RANGE);
617		return StreamSupport.intStream
618		(new RandomIntsSpliterator
619		(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
#	Line 697 | 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("bound must be greater than origin");
640	>	throw new IllegalArgumentException(BAD_RANGE);
641		return StreamSupport.intStream
642		(new RandomIntsSpliterator
643		(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
#	Line 719 | 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 729 | Line 656 | public class SplittableRandom {
656		*/
657		public LongStream longs(long streamSize) {
658		if (streamSize < 0L)
659	<	throw new IllegalArgumentException("negative Stream size");
659	>	throw new IllegalArgumentException(BAD_SIZE);
660		return StreamSupport.longStream
661		(new RandomLongsSpliterator
662		(this, 0L, streamSize, Long.MAX_VALUE, 0L),
#	Line 737 | 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 754 | 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 769 | Line 697 | public class SplittableRandom {
697		public LongStream longs(long streamSize, long randomNumberOrigin,
698		long randomNumberBound) {
699		if (streamSize < 0L)
700	<	throw new IllegalArgumentException("negative Stream size");
700	>	throw new IllegalArgumentException(BAD_SIZE);
701		if (randomNumberOrigin >= randomNumberBound)
702	<	throw new IllegalArgumentException("bound must be greater than origin");
702	>	throw new IllegalArgumentException(BAD_RANGE);
703		return StreamSupport.longStream
704		(new RandomLongsSpliterator
705		(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
#	Line 780 | 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("bound must be greater than origin");
726	>	throw new IllegalArgumentException(BAD_RANGE);
727		return StreamSupport.longStream
728		(new RandomLongsSpliterator
729		(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
#	Line 803 | 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 813 | Line 742 | public class SplittableRandom {
742		*/
743		public DoubleStream doubles(long streamSize) {
744		if (streamSize < 0L)
745	<	throw new IllegalArgumentException("negative Stream size");
745	>	throw new IllegalArgumentException(BAD_SIZE);
746		return StreamSupport.doubleStream
747		(new RandomDoublesSpliterator
748		(this, 0L, streamSize, Double.MAX_VALUE, 0.0),
#	Line 822 | 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 839 | 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("negative Stream size");
788	>	throw new IllegalArgumentException(BAD_SIZE);
789		if (!(randomNumberOrigin < randomNumberBound))
790	<	throw new IllegalArgumentException("bound must be greater than origin");
790	>	throw new IllegalArgumentException(BAD_RANGE);
791		return StreamSupport.doubleStream
792		(new RandomDoublesSpliterator
793		(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
#	Line 866 | 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("bound must be greater than origin");
814	>	throw new IllegalArgumentException(BAD_RANGE);
815		return StreamSupport.doubleStream
816		(new RandomDoublesSpliterator
817		(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
#	Line 895 | 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 938 | Line 870 | public class SplittableRandom {
870		long i = index, f = fence;
871		if (i < f) {
872		index = f;
873	+	SplittableRandom r = rng;
874		int o = origin, b = bound;
875		do {
876	<	consumer.accept(rng.internalNextInt(o, b));
876	>	consumer.accept(r.internalNextInt(o, b));
877		} while (++i < f);
878		}
879		}
#	Line 949 | 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 992 | Line 926 | public class SplittableRandom {
926		long i = index, f = fence;
927		if (i < f) {
928		index = f;
929	+	SplittableRandom r = rng;
930		long o = origin, b = bound;
931		do {
932	<	consumer.accept(rng.internalNextLong(o, b));
932	>	consumer.accept(r.internalNextLong(o, b));
933		} while (++i < f);
934		}
935		}
#	Line 1004 | 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;
#	Line 1047 | Line 983 | public class SplittableRandom {
983		long i = index, f = fence;
984		if (i < f) {
985		index = f;
986	+	SplittableRandom r = rng;
987		double o = origin, b = bound;
988		do {
989	<	consumer.accept(rng.internalNextDouble(o, b));
989	>	consumer.accept(r.internalNextDouble(o, b));
990		} while (++i < f);
991		}
992		}

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