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Comparing jsr166/src/main/java/util/SplittableRandom.java (file contents):
Revision 1.7 by dl, Fri Jul 12 11:26:34 2013 UTC vs.
Revision 1.20 by jsr166, Sat Aug 24 06:20:15 2013 UTC

#	Line 25 | Line 25
25
26		package java.util;
27
28	+	import java.security.SecureRandom;
29	+	import java.net.InetAddress;
30		import java.util.concurrent.atomic.AtomicLong;
29	–	import java.util.Spliterator;
31		import java.util.function.IntConsumer;
32		import java.util.function.LongConsumer;
33		import java.util.function.DoubleConsumer;
#	Line 38 | Line 39 | import java.util.stream.DoubleStream;
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
42	>	* generate subtasks. Class {@code SplittableRandom} supports methods for
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 49 | 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
#	Line 72 | Line 77 | import java.util.stream.DoubleStream;
77		*
78		* </ul>
79		*
80	+	* <p>Instances of {@code SplittableRandom} are not cryptographically
81	+	* secure.  Consider instead using {@link java.security.SecureRandom}
82	+	* in security-sensitive applications. Additionally,
83	+	* default-constructed instances do not use a cryptographically random
84	+	* seed unless the {@linkplain System#getProperty system property}
85	+	* {@code java.util.secureRandomSeed} is set to {@code true}.
86	+	*
87		* @author  Guy Steele
88		* @author  Doug Lea
89		* @since   1.8
#	Line 79 | Line 91 | import java.util.stream.DoubleStream;
91		public class SplittableRandom {
92
93		/*
82	–	* File organization: First the non-public methods that constitute
83	–	* the main algorithm, then the main public methods, followed by
84	–	* some custom spliterator classes needed for stream methods.
85	–	*
86	–	* Credits: Primary algorithm and code by Guy Steele.  Stream
87	–	* support methods by Doug Lea.  Documentation jointly produced
88	–	* with additional help from Brian Goetz.
89	–	*/
90	–
91	–	/*
94		* Implementation Overview.
95		*
96		* This algorithm was inspired by the "DotMix" algorithm by
97		* Leiserson, Schardl, and Sukha "Deterministic Parallel
98		* Random-Number Generation for Dynamic-Multithreading Platforms",
99	<	* PPoPP 2012, but improves and extends it in several ways.
100	<	*
101	<	* The primary update step (see method nextSeed()) is simply to
102	<	* add a constant ("gamma") to the current seed, modulo a prime
103	<	* ("George"). However, the nextLong and nextInt methods do not
104	<	* return this value, but instead the results of bit-mixing
105	<	* transformations that produce more uniformly distributed
106	<	* sequences.
107	<	*
108	<	* "George" is the otherwise nameless (because it cannot be
109	<	* represented) prime number 2^64+13. Using a prime number larger
110	<	* than can fit in a long ensures that all possible long values
111	<	* can occur, plus 13 others that just get skipped over when they
112	<	* are encountered; see method addGammaModGeorge. For this to
113	<	* work, initial gamma values must be at least 13.
112	<	*
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	<	*
133	<	* The mix64 bit-mixing function called by nextLong and other
134	<	* methods computes the same value as the "64-bit finalizer"
135	<	* function in Austin Appleby's MurmurHash3 algorithm.  See
99	>	* PPoPP 2012, as well as those in "Parallel random numbers: as
100	>	* easy as 1, 2, 3" by Salmon, Morae, Dror, and Shaw, SC 2011.  It
101	>	* differs mainly in simplifying and cheapening operations.
102	>	*
103	>	* The primary update step (method nextSeed()) is to add a
104	>	* constant ("gamma") to the current (64 bit) seed, forming a
105	>	* simple sequence.  The seed and the gamma values for any two
106	>	* SplittableRandom instances are highly likely to be different.
107	>	*
108	>	* Methods nextLong, nextInt, and derivatives do not return the
109	>	* sequence (seed) values, but instead a hash-like bit-mix of
110	>	* their bits, producing more independently distributed sequences.
111	>	* For nextLong, the mix64 bit-mixing function computes the same
112	>	* value as the "64-bit finalizer" function in Austin Appleby's
113	>	* MurmurHash3 algorithm.  See
114		* http://code.google.com/p/smhasher/wiki/MurmurHash3 , which
115		* comments: "The constants for the finalizers were generated by a
116		* simple simulated-annealing algorithm, and both avalanche all
117	<	* bits of 'h' to within 0.25% bias." It also appears to work to
118	<	* use instead any of the variants proposed by David Stafford at
119	<	* http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html
120	<	* but these variants have not yet been tested as thoroughly
121	<	* in the context of the implementation of SplittableRandom.
122	<	*
123	<	* The mix32 function used for nextInt just consists of two of the
124	<	* five lines of mix64; avalanche testing shows that the 64-bit result
125	<	* has its top 32 bits avalanched well, though not the bottom 32 bits.
126	<	* DieHarder tests show that it is adequate for generating one
127	<	* random int from the 64-bit result of nextSeed.
128	<	*
129	<	* Support for the default (no-argument) constructor relies on an
130	<	* AtomicLong (defaultSeedGenerator) to help perform the
131	<	* equivalent of a split of a statically constructed
132	<	* SplittableRandom. Unlike other cases, this split must be
133	<	* performed in a thread-safe manner. We use
134	<	* AtomicLong.compareAndSet as the (typically) most efficient
135	<	* mechanism. To bootstrap, we start off using System.nanotime(),
136	<	* and update using another "genuinely random" constant
137	<	* DEFAULT_SEED_GAMMA. The default constructor uses GAMMA_GAMMA,
138	<	* not 0, for its splitSeed argument (addGammaModGeorge(0,
139	<	* GAMMA_GAMMA) == GAMMA_GAMMA) to reflect that each is split from
140	<	* this root generator, even though the root is not explicitly
141	<	* represented as a SplittableRandom.
117	>	* bits of 'h' to within 0.25% bias." The mix32 function is
118	>	* equivalent to (int)(mix64(seed) >>> 32), but faster because it
119	>	* omits a step that doesn't contribute to result.
120	>	*
121	>	* The split operation uses the current generator to form the seed
122	>	* and gamma for another SplittableRandom.  To conservatively
123	>	* avoid potential correlations between seed and value generation,
124	>	* gamma selection (method nextGamma) uses the "Mix13" constants
125	>	* for MurmurHash3 described by David Stafford
126	>	* (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html)
127	>	* To avoid potential weaknesses in bit-mixing transformations, we
128	>	* restrict gammas to odd values with at least 12 and no more than
129	>	* 52 bits set.  Rather than rejecting candidates with too few or
130	>	* too many bits set, method nextGamma flips some bits (which has
131	>	* the effect of mapping at most 4 to any given gamma value).
132	>	* This reduces the effective set of 64bit odd gamma values by
133	>	* about 2<sup>14</sup>, a very tiny percentage, and serves as an
134	>	* automated screening for sequence constant selection that is
135	>	* left as an empirical decision in some other hashing and crypto
136	>	* algorithms.
137	>	*
138	>	* The resulting generator thus transforms a sequence in which
139	>	* (typically) many bits change on each step, with an inexpensive
140	>	* mixer with good (but less than cryptographically secure)
141	>	* avalanching.
142	>	*
143	>	* The default (no-argument) constructor, in essence, invokes
144	>	* split() for a common "seeder" SplittableRandom.  Unlike other
145	>	* cases, this split must be performed in a thread-safe manner, so
146	>	* we use an AtomicLong to represent the seed rather than use an
147	>	* explicit SplittableRandom. To bootstrap the seeder, we start
148	>	* off using a seed based on current time and host unless the
149	>	* java.util.secureRandomSeed property is set. This serves as a
150	>	* slimmed-down (and insecure) variant of SecureRandom that also
151	>	* avoids stalls that may occur when using /dev/random.
152	>	*
153	>	* It is a relatively simple matter to apply the basic design here
154	>	* to use 128 bit seeds. However, emulating 128bit arithmetic and
155	>	* carrying around twice the state add more overhead than appears
156	>	* warranted for current usages.
157	>	*
158	>	* File organization: First the non-public methods that constitute
159	>	* the main algorithm, then the main public methods, followed by
160	>	* some custom spliterator classes needed for stream methods.
161		*/
162
163		/**
164	<	* The "genuinely random" value for producing new gamma values.
165	<	* The value is arbitrary, subject to the requirement that it be
166	<	* greater or equal to 13.
170	<	*/
171	<	private static final long GAMMA_GAMMA = 0xF2281E2DBA6606F3L;
172	<
173	<	/**
174	<	* The "genuinely random" seed update value for default constructors.
175	<	* The value is arbitrary, subject to the requirement that it be
176	<	* greater or equal to 13.
164	>	* The initial gamma value for (unsplit) SplittableRandoms. Must
165	>	* be odd with at least 12 and no more than 52 bits set. Currently
166	>	* set to the golden ratio scaled to 64bits.
167		*/
168	<	private static final long DEFAULT_SEED_GAMMA = 0xBD24B73A95FB84D9L;
168	>	private static final long INITIAL_GAMMA = 0x9e3779b97f4a7c15L;
169
170		/**
171		* The least non-zero value returned by nextDouble(). This value
#	Line 184 | Line 174 | public class SplittableRandom {
174		private static final double DOUBLE_UNIT = 1.0 / (1L << 53);
175
176		/**
177	<	* The next seed for default constructors.
188	<	*/
189	<	private static final AtomicLong defaultSeedGenerator =
190	<	new AtomicLong(System.nanoTime());
191	<
192	<	/**
193	<	* The seed, updated only via method nextSeed.
177	>	* The seed. Updated only via method nextSeed.
178		*/
179		private long seed;
180
181		/**
182	<	* The constant value added to seed (mod George) on each update.
182	>	* The step value.
183		*/
184		private final long gamma;
185
186		/**
187	<	* The next seed to use for splits. Propagated using
204	<	* addGammaModGeorge across instances.
187	>	* Internal constructor used by all others except default constructor.
188		*/
189	<	private final long nextSplit;
190	<
191	<	/**
209	<	* Adds the given gamma value, g, to the given seed value s, mod
210	<	* George (2^64+13). We regard s and g as unsigned values
211	<	* (ranging from 0 to 2^64-1). We add g to s either once or twice
212	<	* (mod George) as necessary to produce an (unsigned) result less
213	<	* than 2^64.  We require that g must be at least 13. This
214	<	* guarantees that if (s+g) mod George >= 2^64 then (s+g+g) mod
215	<	* George < 2^64; thus we need only a conditional, not a loop,
216	<	* to be sure of getting a representable value.
217	<	*
218	<	* @param s a seed value
219	<	* @param g a gamma value, 13 <= g (as unsigned)
220	<	*/
221	<	private static long addGammaModGeorge(long s, long g) {
222	<	long p = s + g;
223	<	if (Long.compareUnsigned(p, g) >= 0)
224	<	return p;
225	<	long q = p - 13L;
226	<	return (Long.compareUnsigned(p, 13L) >= 0) ? q : (q + g);
189	>	private SplittableRandom(long seed, long gamma) {
190	>	this.seed = seed;
191	>	this.gamma = gamma;
192		}
193
194		/**
195	<	* Returns a bit-mixed transformation of its argument.
231	<	* See above for explanation.
195	>	* Computes MurmurHash3 64bit mix function.
196		*/
197		private static long mix64(long z) {
198	<	z ^= (z >>> 33);
199	<	z *= 0xff51afd7ed558ccdL;
200	<	z ^= (z >>> 33);
237	<	z *= 0xc4ceb9fe1a85ec53L;
238	<	z ^= (z >>> 33);
239	<	return z;
198	>	z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
199	>	z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
200	>	return z ^ (z >>> 33);
201		}
202
203		/**
204	<	* Returns a bit-mixed int transformation of its argument.
244	<	* See above for explanation.
204	>	* Returns the 32 high bits of mix64(z) as int.
205		*/
206		private static int mix32(long z) {
207	<	z ^= (z >>> 33);
208	<	z *= 0xc4ceb9fe1a85ec53L;
249	<	return (int)(z >>> 32);
207	>	z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
208	>	return (int)(((z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L) >>> 32);
209		}
210
211		/**
212	<	* Internal constructor used by all other constructors and by
254	<	* method split. Establishes the initial seed for this instance,
255	<	* and uses the given splitSeed to establish gamma, as well as the
256	<	* nextSplit to use by this instance. The loop to skip ineligible
257	<	* gammas very rarely iterates, and does so at most 13 times.
212	>	* Returns the gamma value to use for a new split instance.
213		*/
214	<	private SplittableRandom(long seed, long splitSeed) {
215	<	this.seed = seed;
216	<	long s = splitSeed, g;
217	<	do { // ensure gamma >= 13, considered as an unsigned integer
218	<	s = addGammaModGeorge(s, GAMMA_GAMMA);
219	<	g = mix64(s);
265	<	} while (Long.compareUnsigned(g, 13L) < 0);
266	<	this.gamma = g;
267	<	this.nextSplit = s;
214	>	private static long nextGamma(long z) {
215	>	z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L; // Stafford "Mix13"
216	>	z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
217	>	z = (z ^ (z >>> 31)) | 1L; // force to be odd
218	>	int n = Long.bitCount(z);  // ensure enough 0 and 1 bits
219	>	return (n < 12 || n > 52) ? z ^ 0xaaaaaaaaaaaaaaaaL : z;
220		}
221
222		/**
223	<	* Updates in-place and returns seed.
272	<	* See above for explanation.
223	>	* Adds gamma to seed.
224		*/
225		private long nextSeed() {
226	<	return seed = addGammaModGeorge(seed, gamma);
226	>	return seed += gamma;
227		}
228
229		/**
230	<	* Atomically updates and returns next seed for default constructor.
230	>	* The seed generator for default constructors.
231		*/
232	<	private static long nextDefaultSeed() {
233	<	long oldSeed, newSeed;
234	<	do {
235	<	oldSeed = defaultSeedGenerator.get();
236	<	newSeed = addGammaModGeorge(oldSeed, DEFAULT_SEED_GAMMA);
237	<	} while (!defaultSeedGenerator.compareAndSet(oldSeed, newSeed));
238	<	return mix64(newSeed);
232	>	private static final AtomicLong seeder = new AtomicLong(initialSeed());
233	>
234	>	private static long initialSeed() {
235	>	try {  // ignore exceptions in accessing/parsing properties
236	>	String pp = System.getProperty
237	>	("java.util.secureRandomSeed");
238	>	if (pp != null && pp.equalsIgnoreCase("true")) {
239	>	byte[] seedBytes = java.security.SecureRandom.getSeed(8);
240	>	long s = (long)(seedBytes[0]) & 0xffL;
241	>	for (int i = 1; i < 8; ++i)
242	>	s = (s << 8) | ((long)(seedBytes[i]) & 0xffL);
243	>	return s;
244	>	}
245	>	} catch (Exception ignore) {
246	>	}
247	>	int hh = 0; // hashed host address
248	>	try {
249	>	hh = InetAddress.getLocalHost().hashCode();
250	>	} catch (Exception ignore) {
251	>	}
252	>	return (mix64((((long)hh) << 32) ^ System.currentTimeMillis()) ^
253	>	mix64(System.nanoTime()));
254		}
255
256	+	// IllegalArgumentException messages
257	+	static final String BadBound = "bound must be positive";
258	+	static final String BadRange = "bound must be greater than origin";
259	+	static final String BadSize  = "size must be non-negative";
260	+
261		/*
262		* Internal versions of nextX methods used by streams, as well as
263		* the public nextX(origin, bound) methods.  These exist mainly to
#	Line 362 | Line 333 | public class SplittableRandom {
333		int r = mix32(nextSeed());
334		if (origin < bound) {
335		int n = bound - origin, m = n - 1;
336	<	if ((n & m) == 0L)
336	>	if ((n & m) == 0)
337		r = (r & m) + origin;
338		else if (n > 0) {
339		for (int u = r >>> 1;
#	Line 401 | Line 372 | public class SplittableRandom {
372		/**
373		* Creates a new SplittableRandom instance using the specified
374		* initial seed. SplittableRandom instances created with the same
375	<	* seed generate identical sequences of values.
375	>	* seed in the same program generate identical sequences of values.
376		*
377		* @param seed the initial seed
378		*/
379		public SplittableRandom(long seed) {
380	<	this(seed, 0);
380	>	this(seed, INITIAL_GAMMA);
381		}
382
383		/**
#	Line 415 | Line 386 | public class SplittableRandom {
386		* of those of any other instances in the current program; and
387		* may, and typically does, vary across program invocations.
388		*/
389	<	public SplittableRandom() {
390	<	this(nextDefaultSeed(), GAMMA_GAMMA);
389	>	public SplittableRandom() { // emulate seeder.split()
390	>	this.gamma = nextGamma(this.seed = seeder.addAndGet(INITIAL_GAMMA));
391		}
392
393		/**
#	Line 434 | Line 405 | public class SplittableRandom {
405		* @return the new SplittableRandom instance
406		*/
407		public SplittableRandom split() {
408	<	return new SplittableRandom(nextSeed(), nextSplit);
408	>	long s = nextSeed();
409	>	return new SplittableRandom(s, nextGamma(s));
410		}
411
412		/**
#	Line 450 | Line 422 | public class SplittableRandom {
422		* Returns a pseudorandom {@code int} value between zero (inclusive)
423		* and the specified bound (exclusive).
424		*
425	<	* @param bound the bound on the random number to be returned.  Must be
454	<	*        positive.
425	>	* @param bound the upper bound (exclusive).  Must be positive.
426		* @return a pseudorandom {@code int} value between zero
427	<	*         (inclusive) and the bound (exclusive).
428	<	* @throws IllegalArgumentException if the bound is less than zero
427	>	*         (inclusive) and the bound (exclusive)
428	>	* @throws IllegalArgumentException if {@code bound} is not positive
429		*/
430		public int nextInt(int bound) {
431		if (bound <= 0)
432	<	throw new IllegalArgumentException("bound must be positive");
432	>	throw new IllegalArgumentException(BadBound);
433		// Specialize internalNextInt for origin 0
434		int r = mix32(nextSeed());
435		int m = bound - 1;
436	<	if ((bound & m) == 0L) // power of two
436	>	if ((bound & m) == 0) // power of two
437		r &= m;
438		else { // reject over-represented candidates
439		for (int u = r >>> 1;
#	Line 480 | Line 451 | public class SplittableRandom {
451		* @param origin the least value returned
452		* @param bound the upper bound (exclusive)
453		* @return a pseudorandom {@code int} value between the origin
454	<	*         (inclusive) and the bound (exclusive).
454	>	*         (inclusive) and the bound (exclusive)
455		* @throws IllegalArgumentException if {@code origin} is greater than
456		*         or equal to {@code bound}
457		*/
458		public int nextInt(int origin, int bound) {
459		if (origin >= bound)
460	<	throw new IllegalArgumentException("bound must be greater than origin");
460	>	throw new IllegalArgumentException(BadRange);
461		return internalNextInt(origin, bound);
462		}
463
#	Line 503 | Line 474 | public class SplittableRandom {
474		* Returns a pseudorandom {@code long} value between zero (inclusive)
475		* and the specified bound (exclusive).
476		*
477	<	* @param bound the bound on the random number to be returned.  Must be
507	<	*        positive.
477	>	* @param bound the upper bound (exclusive).  Must be positive.
478		* @return a pseudorandom {@code long} value between zero
479	<	*         (inclusive) and the bound (exclusive).
480	<	* @throws IllegalArgumentException if {@code bound} is less than zero
479	>	*         (inclusive) and the bound (exclusive)
480	>	* @throws IllegalArgumentException if {@code bound} is not positive
481		*/
482		public long nextLong(long bound) {
483		if (bound <= 0)
484	<	throw new IllegalArgumentException("bound must be positive");
484	>	throw new IllegalArgumentException(BadBound);
485		// Specialize internalNextLong for origin 0
486		long r = mix64(nextSeed());
487		long m = bound - 1;
#	Line 533 | Line 503 | public class SplittableRandom {
503		* @param origin the least value returned
504		* @param bound the upper bound (exclusive)
505		* @return a pseudorandom {@code long} value between the origin
506	<	*         (inclusive) and the bound (exclusive).
506	>	*         (inclusive) and the bound (exclusive)
507		* @throws IllegalArgumentException if {@code origin} is greater than
508		*         or equal to {@code bound}
509		*/
510		public long nextLong(long origin, long bound) {
511		if (origin >= bound)
512	<	throw new IllegalArgumentException("bound must be greater than origin");
512	>	throw new IllegalArgumentException(BadRange);
513		return internalNextLong(origin, bound);
514		}
515
#	Line 548 | Line 518 | public class SplittableRandom {
518		* (inclusive) and one (exclusive).
519		*
520		* @return a pseudorandom {@code double} value between zero
521	<	* (inclusive) and one (exclusive)
521	>	*         (inclusive) and one (exclusive)
522		*/
523		public double nextDouble() {
524	<	return (nextLong() >>> 11) * DOUBLE_UNIT;
524	>	return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT;
525		}
526
527		/**
528		* Returns a pseudorandom {@code double} value between 0.0
529		* (inclusive) and the specified bound (exclusive).
530		*
531	<	* @param bound the bound on the random number to be returned.  Must be
562	<	*        positive.
531	>	* @param bound the upper bound (exclusive).  Must be positive.
532		* @return a pseudorandom {@code double} value between zero
533	<	*         (inclusive) and the bound (exclusive).
534	<	* @throws IllegalArgumentException if {@code bound} is less than zero
533	>	*         (inclusive) and the bound (exclusive)
534	>	* @throws IllegalArgumentException if {@code bound} is not positive
535		*/
536		public double nextDouble(double bound) {
537		if (!(bound > 0.0))
538	<	throw new IllegalArgumentException("bound must be positive");
539	<	double result = nextDouble() * bound;
538	>	throw new IllegalArgumentException(BadBound);
539	>	double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound;
540		return (result < bound) ?  result : // correct for rounding
541		Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
542		}
#	Line 577 | Line 546 | public class SplittableRandom {
546		* origin (inclusive) and bound (exclusive).
547		*
548		* @param origin the least value returned
549	<	* @param bound the upper bound
549	>	* @param bound the upper bound (exclusive)
550		* @return a pseudorandom {@code double} value between the origin
551	<	*         (inclusive) and the bound (exclusive).
551	>	*         (inclusive) and the bound (exclusive)
552		* @throws IllegalArgumentException if {@code origin} is greater than
553		*         or equal to {@code bound}
554		*/
555		public double nextDouble(double origin, double bound) {
556		if (!(origin < bound))
557	<	throw new IllegalArgumentException("bound must be greater than origin");
557	>	throw new IllegalArgumentException(BadRange);
558		return internalNextDouble(origin, bound);
559		}
560
561	+	/**
562	+	* Returns a pseudorandom {@code boolean} value.
563	+	*
564	+	* @return a pseudorandom {@code boolean} value
565	+	*/
566	+	public boolean nextBoolean() {
567	+	return mix32(nextSeed()) < 0;
568	+	}
569	+
570		// stream methods, coded in a way intended to better isolate for
571		// maintenance purposes the small differences across forms.
572
573		/**
574	<	* Returns a stream producing the given {@code streamSize} number of
575	<	* pseudorandom {@code int} values.
574	>	* Returns a stream producing the given {@code streamSize} number
575	>	* of pseudorandom {@code int} values from this generator and/or
576	>	* one split from it.
577		*
578		* @param streamSize the number of values to generate
579		* @return a stream of pseudorandom {@code int} values
#	Line 603 | Line 582 | public class SplittableRandom {
582		*/
583		public IntStream ints(long streamSize) {
584		if (streamSize < 0L)
585	<	throw new IllegalArgumentException("negative Stream size");
585	>	throw new IllegalArgumentException(BadSize);
586		return StreamSupport.intStream
587		(new RandomIntsSpliterator
588		(this, 0L, streamSize, Integer.MAX_VALUE, 0),
#	Line 612 | Line 591 | public class SplittableRandom {
591
592		/**
593		* Returns an effectively unlimited stream of pseudorandom {@code int}
594	<	* values
594	>	* values from this generator and/or one split from it.
595		*
596		* @implNote This method is implemented to be equivalent to {@code
597		* ints(Long.MAX_VALUE)}.
#	Line 627 | Line 606 | public class SplittableRandom {
606		}
607
608		/**
609	<	* Returns a stream producing the given {@code streamSize} number of
610	<	* pseudorandom {@code int} values, each conforming to the given
611	<	* origin and bound.
609	>	* Returns a stream producing the given {@code streamSize} number
610	>	* of pseudorandom {@code int} values from this generator and/or one split
611	>	* from it; each value conforms to the given origin (inclusive) and bound
612	>	* (exclusive).
613		*
614		* @param streamSize the number of values to generate
615	<	* @param randomNumberOrigin the origin of each random value
616	<	* @param randomNumberBound the bound of each random value
615	>	* @param randomNumberOrigin the origin (inclusive) of each random value
616	>	* @param randomNumberBound the bound (exclusive) of each random value
617		* @return a stream of pseudorandom {@code int} values,
618	<	*         each with the given origin and bound.
618	>	*         each with the given origin (inclusive) and bound (exclusive)
619		* @throws IllegalArgumentException if {@code streamSize} is
620		*         less than zero, or {@code randomNumberOrigin}
621		*         is greater than or equal to {@code randomNumberBound}
#	Line 643 | Line 623 | public class SplittableRandom {
623		public IntStream ints(long streamSize, int randomNumberOrigin,
624		int randomNumberBound) {
625		if (streamSize < 0L)
626	<	throw new IllegalArgumentException("negative Stream size");
626	>	throw new IllegalArgumentException(BadSize);
627		if (randomNumberOrigin >= randomNumberBound)
628	<	throw new IllegalArgumentException("bound must be greater than origin");
628	>	throw new IllegalArgumentException(BadRange);
629		return StreamSupport.intStream
630		(new RandomIntsSpliterator
631		(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
#	Line 654 | Line 634 | public class SplittableRandom {
634
635		/**
636		* Returns an effectively unlimited stream of pseudorandom {@code
637	<	* int} values, each conforming to the given origin and bound.
637	>	* int} values from this generator and/or one split from it; each value
638	>	* conforms to the given origin (inclusive) and bound (exclusive).
639		*
640		* @implNote This method is implemented to be equivalent to {@code
641		* ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
642		*
643	<	* @param randomNumberOrigin the origin of each random value
644	<	* @param randomNumberBound the bound of each random value
643	>	* @param randomNumberOrigin the origin (inclusive) of each random value
644	>	* @param randomNumberBound the bound (exclusive) of each random value
645		* @return a stream of pseudorandom {@code int} values,
646	<	*         each with the given origin and bound.
646	>	*         each with the given origin (inclusive) and bound (exclusive)
647		* @throws IllegalArgumentException if {@code randomNumberOrigin}
648		*         is greater than or equal to {@code randomNumberBound}
649		*/
650		public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
651		if (randomNumberOrigin >= randomNumberBound)
652	<	throw new IllegalArgumentException("bound must be greater than origin");
652	>	throw new IllegalArgumentException(BadRange);
653		return StreamSupport.intStream
654		(new RandomIntsSpliterator
655		(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
#	Line 676 | Line 657 | public class SplittableRandom {
657		}
658
659		/**
660	<	* Returns a stream producing the given {@code streamSize} number of
661	<	* pseudorandom {@code long} values.
660	>	* Returns a stream producing the given {@code streamSize} number
661	>	* of pseudorandom {@code long} values from this generator and/or
662	>	* one split from it.
663		*
664		* @param streamSize the number of values to generate
665		* @return a stream of pseudorandom {@code long} values
#	Line 686 | Line 668 | public class SplittableRandom {
668		*/
669		public LongStream longs(long streamSize) {
670		if (streamSize < 0L)
671	<	throw new IllegalArgumentException("negative Stream size");
671	>	throw new IllegalArgumentException(BadSize);
672		return StreamSupport.longStream
673		(new RandomLongsSpliterator
674		(this, 0L, streamSize, Long.MAX_VALUE, 0L),
#	Line 694 | Line 676 | public class SplittableRandom {
676		}
677
678		/**
679	<	* Returns an effectively unlimited stream of pseudorandom {@code long}
680	<	* values.
679	>	* Returns an effectively unlimited stream of pseudorandom {@code
680	>	* long} values from this generator and/or one split from it.
681		*
682		* @implNote This method is implemented to be equivalent to {@code
683		* longs(Long.MAX_VALUE)}.
#	Line 711 | Line 693 | public class SplittableRandom {
693
694		/**
695		* Returns a stream producing the given {@code streamSize} number of
696	<	* pseudorandom {@code long} values, each conforming to the
697	<	* given origin and bound.
696	>	* pseudorandom {@code long} values from this generator and/or one split
697	>	* from it; each value conforms to the given origin (inclusive) and bound
698	>	* (exclusive).
699		*
700		* @param streamSize the number of values to generate
701	<	* @param randomNumberOrigin the origin of each random value
702	<	* @param randomNumberBound the bound of each random value
701	>	* @param randomNumberOrigin the origin (inclusive) of each random value
702	>	* @param randomNumberBound the bound (exclusive) of each random value
703		* @return a stream of pseudorandom {@code long} values,
704	<	*         each with the given origin and bound.
704	>	*         each with the given origin (inclusive) and bound (exclusive)
705		* @throws IllegalArgumentException if {@code streamSize} is
706		*         less than zero, or {@code randomNumberOrigin}
707		*         is greater than or equal to {@code randomNumberBound}
#	Line 726 | Line 709 | public class SplittableRandom {
709		public LongStream longs(long streamSize, long randomNumberOrigin,
710		long randomNumberBound) {
711		if (streamSize < 0L)
712	<	throw new IllegalArgumentException("negative Stream size");
712	>	throw new IllegalArgumentException(BadSize);
713		if (randomNumberOrigin >= randomNumberBound)
714	<	throw new IllegalArgumentException("bound must be greater than origin");
714	>	throw new IllegalArgumentException(BadRange);
715		return StreamSupport.longStream
716		(new RandomLongsSpliterator
717		(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
#	Line 737 | Line 720 | public class SplittableRandom {
720
721		/**
722		* Returns an effectively unlimited stream of pseudorandom {@code
723	<	* long} values, each conforming to the given origin and bound.
723	>	* long} values from this generator and/or one split from it; each value
724	>	* conforms to the given origin (inclusive) and bound (exclusive).
725		*
726		* @implNote This method is implemented to be equivalent to {@code
727		* longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
728		*
729	<	* @param randomNumberOrigin the origin of each random value
730	<	* @param randomNumberBound the bound of each random value
729	>	* @param randomNumberOrigin the origin (inclusive) of each random value
730	>	* @param randomNumberBound the bound (exclusive) of each random value
731		* @return a stream of pseudorandom {@code long} values,
732	<	*         each with the given origin and bound.
732	>	*         each with the given origin (inclusive) and bound (exclusive)
733		* @throws IllegalArgumentException if {@code randomNumberOrigin}
734		*         is greater than or equal to {@code randomNumberBound}
735		*/
736		public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
737		if (randomNumberOrigin >= randomNumberBound)
738	<	throw new IllegalArgumentException("bound must be greater than origin");
738	>	throw new IllegalArgumentException(BadRange);
739		return StreamSupport.longStream
740		(new RandomLongsSpliterator
741		(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
#	Line 760 | Line 744 | public class SplittableRandom {
744
745		/**
746		* Returns a stream producing the given {@code streamSize} number of
747	<	* pseudorandom {@code double} values, each between zero
748	<	* (inclusive) and one (exclusive).
747	>	* pseudorandom {@code double} values from this generator and/or one split
748	>	* from it; each value is between zero (inclusive) and one (exclusive).
749		*
750		* @param streamSize the number of values to generate
751		* @return a stream of {@code double} values
#	Line 770 | Line 754 | public class SplittableRandom {
754		*/
755		public DoubleStream doubles(long streamSize) {
756		if (streamSize < 0L)
757	<	throw new IllegalArgumentException("negative Stream size");
757	>	throw new IllegalArgumentException(BadSize);
758		return StreamSupport.doubleStream
759		(new RandomDoublesSpliterator
760		(this, 0L, streamSize, Double.MAX_VALUE, 0.0),
#	Line 779 | Line 763 | public class SplittableRandom {
763
764		/**
765		* Returns an effectively unlimited stream of pseudorandom {@code
766	<	* double} values, each between zero (inclusive) and one
767	<	* (exclusive).
766	>	* double} values from this generator and/or one split from it; each value
767	>	* is between zero (inclusive) and one (exclusive).
768		*
769		* @implNote This method is implemented to be equivalent to {@code
770		* doubles(Long.MAX_VALUE)}.
#	Line 796 | Line 780 | public class SplittableRandom {
780
781		/**
782		* Returns a stream producing the given {@code streamSize} number of
783	<	* pseudorandom {@code double} values, each conforming to the
784	<	* given origin and bound.
783	>	* pseudorandom {@code double} values from this generator and/or one split
784	>	* from it; each value conforms to the given origin (inclusive) and bound
785	>	* (exclusive).
786		*
787		* @param streamSize the number of values to generate
788	<	* @param randomNumberOrigin the origin of each random value
789	<	* @param randomNumberBound the bound of each random value
788	>	* @param randomNumberOrigin the origin (inclusive) of each random value
789	>	* @param randomNumberBound the bound (exclusive) of each random value
790		* @return a stream of pseudorandom {@code double} values,
791	<	* each with the given origin and bound.
791	>	*         each with the given origin (inclusive) and bound (exclusive)
792		* @throws IllegalArgumentException if {@code streamSize} is
793	<	* less than zero.
793	>	*         less than zero
794		* @throws IllegalArgumentException if {@code randomNumberOrigin}
795		*         is greater than or equal to {@code randomNumberBound}
796		*/
797		public DoubleStream doubles(long streamSize, double randomNumberOrigin,
798		double randomNumberBound) {
799		if (streamSize < 0L)
800	<	throw new IllegalArgumentException("negative Stream size");
800	>	throw new IllegalArgumentException(BadSize);
801		if (!(randomNumberOrigin < randomNumberBound))
802	<	throw new IllegalArgumentException("bound must be greater than origin");
802	>	throw new IllegalArgumentException(BadRange);
803		return StreamSupport.doubleStream
804		(new RandomDoublesSpliterator
805		(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
#	Line 823 | Line 808 | public class SplittableRandom {
808
809		/**
810		* Returns an effectively unlimited stream of pseudorandom {@code
811	<	* double} values, each conforming to the given origin and bound.
811	>	* double} values from this generator and/or one split from it; each value
812	>	* conforms to the given origin (inclusive) and bound (exclusive).
813		*
814		* @implNote This method is implemented to be equivalent to {@code
815		* doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
816		*
817	<	* @param randomNumberOrigin the origin of each random value
818	<	* @param randomNumberBound the bound of each random value
817	>	* @param randomNumberOrigin the origin (inclusive) of each random value
818	>	* @param randomNumberBound the bound (exclusive) of each random value
819		* @return a stream of pseudorandom {@code double} values,
820	<	* each with the given origin and bound.
820	>	*         each with the given origin (inclusive) and bound (exclusive)
821		* @throws IllegalArgumentException if {@code randomNumberOrigin}
822		*         is greater than or equal to {@code randomNumberBound}
823		*/
824		public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
825		if (!(randomNumberOrigin < randomNumberBound))
826	<	throw new IllegalArgumentException("bound must be greater than origin");
826	>	throw new IllegalArgumentException(BadRange);
827		return StreamSupport.doubleStream
828		(new RandomDoublesSpliterator
829		(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
#	Line 852 | Line 838 | public class SplittableRandom {
838		* approach. The long and double versions of this class are
839		* identical except for types.
840		*/
841	<	static class RandomIntsSpliterator implements Spliterator.OfInt {
841	>	static final class RandomIntsSpliterator implements Spliterator.OfInt {
842		final SplittableRandom rng;
843		long index;
844		final long fence;
#	Line 895 | Line 881 | public class SplittableRandom {
881		long i = index, f = fence;
882		if (i < f) {
883		index = f;
884	+	SplittableRandom r = rng;
885		int o = origin, b = bound;
886		do {
887	<	consumer.accept(rng.internalNextInt(o, b));
887	>	consumer.accept(r.internalNextInt(o, b));
888		} while (++i < f);
889		}
890		}
#	Line 906 | Line 893 | public class SplittableRandom {
893		/**
894		* Spliterator for long streams.
895		*/
896	<	static class RandomLongsSpliterator implements Spliterator.OfLong {
896	>	static final class RandomLongsSpliterator implements Spliterator.OfLong {
897		final SplittableRandom rng;
898		long index;
899		final long fence;
#	Line 949 | Line 936 | public class SplittableRandom {
936		long i = index, f = fence;
937		if (i < f) {
938		index = f;
939	+	SplittableRandom r = rng;
940		long o = origin, b = bound;
941		do {
942	<	consumer.accept(rng.internalNextLong(o, b));
942	>	consumer.accept(r.internalNextLong(o, b));
943		} while (++i < f);
944		}
945		}
#	Line 961 | Line 949 | public class SplittableRandom {
949		/**
950		* Spliterator for double streams.
951		*/
952	<	static class RandomDoublesSpliterator implements Spliterator.OfDouble {
952	>	static final class RandomDoublesSpliterator implements Spliterator.OfDouble {
953		final SplittableRandom rng;
954		long index;
955		final long fence;
#	Line 1004 | Line 992 | public class SplittableRandom {
992		long i = index, f = fence;
993		if (i < f) {
994		index = f;
995	+	SplittableRandom r = rng;
996		double o = origin, b = bound;
997		do {
998	<	consumer.accept(rng.internalNextDouble(o, b));
998	>	consumer.accept(r.internalNextDouble(o, b));
999		} while (++i < f);
1000		}
1001		}
1002		}
1003
1004		}
1016	–

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