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1 : dl 1.1 /*
2 :     * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
3 :     * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 :     *
5 :     * This code is free software; you can redistribute it and/or modify it
6 :     * under the terms of the GNU General Public License version 2 only, as
7 :     * published by the Free Software Foundation. Oracle designates this
8 :     * particular file as subject to the "Classpath" exception as provided
9 :     * by Oracle in the LICENSE file that accompanied this code.
10 :     *
11 :     * This code is distributed in the hope that it will be useful, but WITHOUT
12 :     * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 :     * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 :     * version 2 for more details (a copy is included in the LICENSE file that
15 :     * accompanied this code).
16 :     *
17 :     * You should have received a copy of the GNU General Public License version
18 :     * 2 along with this work; if not, write to the Free Software Foundation,
19 :     * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 :     *
21 :     * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 :     * or visit www.oracle.com if you need additional information or have any
23 :     * questions.
24 :     */
25 :    
26 :     package java.util;
27 :    
28 :     import java.util.concurrent.atomic.AtomicLong;
29 :     import java.util.Spliterator;
30 :     import java.util.function.IntConsumer;
31 :     import java.util.function.LongConsumer;
32 :     import java.util.function.DoubleConsumer;
33 :     import java.util.stream.StreamSupport;
34 :     import java.util.stream.IntStream;
35 :     import java.util.stream.LongStream;
36 :     import java.util.stream.DoubleStream;
37 :    
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},
44 :     * and {@code double} with similar usages as for class
45 :     * {@link java.util.Random} but differs in the following ways: <ul>
46 :     *
47 :     * <li>Series of generated values pass the DieHarder suite testing
48 :     * independence and uniformity properties of random number generators.
49 :     * (Most recently validated with <a
50 :     * href="http://www.phy.duke.edu/~rgb/General/dieharder.php"> version
51 :     * 3.31.1</a>.) These tests validate only the methods for certain
52 :     * types and ranges, but similar properties are expected to hold, at
53 :     * least approximately, for others as well. </li>
54 :     *
55 :     * <li> Method {@link #split} constructs and returns a new
56 :     * SplittableRandom instance that shares no mutable state with the
57 :     * current instance. However, with very high probability, the set of
58 :     * values collectively generated by the two objects has the same
59 :     * statistical properties as if the same quantity of values were
60 :     * generated by a single thread using a single {@code
61 :     * SplittableRandom} object. </li>
62 :     *
63 :     * <li>Instances of SplittableRandom are <em>not</em> thread-safe.
64 :     * They are designed to be split, not shared, across threads. For
65 :     * example, a {@link java.util.concurrent.ForkJoinTask
66 :     * fork/join-style} computation using random numbers might include a
67 :     * construction of the form {@code new
68 :     * Subtask(aSplittableRandom.split()).fork()}.
69 :     *
70 :     * <li>This class provides additional methods for generating random
71 :     * streams, that employ the above techniques when used in {@code
72 :     * stream.parallel()} mode.</li>
73 :     *
74 :     * </ul>
75 :     *
76 :     * @author Guy Steele
77 :     * @since 1.8
78 :     */
79 :     public class SplittableRandom {
80 :    
81 :     /*
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 :     /*
92 :     * Implementation Overview.
93 :     *
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.
98 :     *
99 :     * The primary update step is simply to add a constant ("gamma")
100 :     * to the current seed, modulo a prime ("George"). However, the
101 :     * nextLong and nextInt methods do not return this value, but
102 :     * instead the results of bit-mixing transformations that produce
103 :     * more uniformly distributed sequences.
104 :     *
105 :     * "George" is the otherwise nameless (because it cannot be
106 :     * represented) prime number 2^64+13. Using a prime number larger
107 :     * than can fit in a long ensures that all possible long values
108 :     * can occur, plus 13 others that just get skipped over when they
109 :     * are encountered; see method addGammaModGeorge. For this to
110 :     * work, initial gamma values must be at least 13.
111 :     *
112 :     * The value of gamma differs for each instance across a series of
113 :     * splits, and is generated using a slightly stripped-down variant
114 :     * of the same algorithm, but operating across calls to split(),
115 :     * not calls to nextLong(): Each instance carries the state of
116 :     * this generator as nextSplit, and uses mix64(nextSplit) as its
117 :     * own gamma value. Computations of gammas themselves use a fixed
118 :     * constant as the second argument to the addGammaModGeorge
119 :     * function, GAMMA_GAMMA, a "genuinely random" number from a
120 :     * radioactive decay reading (obtained from
121 :     * http://www.fourmilab.ch/hotbits/) meeting the above range
122 :     * constraint. Using a fixed constant maintains the invariant that
123 :     * the value of gamma is the same for every instance that is at
124 :     * the same split-distance from their common root. (Note: there is
125 :     * nothing especially magic about obtaining this constant from a
126 :     * "truly random" physical source rather than just choosing one
127 :     * arbitrarily; using "hotbits" was merely an aesthetically pleasing
128 :     * choice. In either case, good statistical behavior of the
129 :     * algorithm should be, and was, verified by using the DieHarder
130 :     * test suite.)
131 :     *
132 :     * The mix64 bit-mixing function called by nextLong and other
133 :     * methods computes the same value as the "64-bit finalizer"
134 :     * function in Austin Appleby's MurmurHash3 algorithm. See
135 :     * http://code.google.com/p/smhasher/wiki/MurmurHash3 , which
136 :     * comments: "The constants for the finalizers were generated by a
137 :     * simple simulated-annealing algorithm, and both avalanche all
138 :     * bits of 'h' to within 0.25% bias." It also appears to work to
139 :     * use instead any of the variants proposed by David Stafford at
140 :     * http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html
141 :     * but these variants have not yet been tested as thoroughly
142 :     * in the context of the implementation of SplittableRandom.
143 :     *
144 :     * The mix32 function used for nextInt just consists of two of the
145 :     * five lines of mix64; avalanche testing shows that the 64-bit result
146 :     * has its top 32 bits avalanched well, though not the bottom 32 bits.
147 :     * DieHarder tests show that it is adequate for generating one
148 :     * random int from the 64-bit result of nextSeed.
149 :     *
150 :     * Support for the default (no-argument) constructor relies on an
151 :     * AtomicLong (defaultSeedGenerator) to help perform the
152 :     * equivalent of a split of a statically constructed
153 :     * SplittableRandom. Unlike other cases, this split must be
154 :     * performed in a thread-safe manner. We use
155 :     * AtomicLong.compareAndSet as the (typically) most efficient
156 :     * mechanism. To bootstrap, we start off using System.nanotime(),
157 :     * and update using another "genuinely random" constant
158 :     * DEFAULT_SEED_GAMMA. The default constructor uses GAMMA_GAMMA,
159 :     * not 0, for its splitSeed argument (addGammaModGeorge(0,
160 :     * GAMMA_GAMMA) == GAMMA_GAMMA) to reflect that each is split from
161 :     * this root generator, even though the root is not explicitly
162 :     * represented as a SplittableRandom.
163 :     */
164 :    
165 :     /**
166 :     * The "genuinely random" value for producing new gamma values.
167 :     * The value is arbitrary, subject to the requirement that it be
168 :     * greater or equal to 13.
169 :     */
170 :     private static final long GAMMA_GAMMA = 0xF2281E2DBA6606F3L;
171 :    
172 :     /**
173 :     * The "genuinely random" seed update value for default constructors.
174 :     * The value is arbitrary, subject to the requirement that it be
175 :     * greater or equal to 13.
176 :     */
177 :     private static final long DEFAULT_SEED_GAMMA = 0xBD24B73A95FB84D9L;
178 :    
179 :     /**
180 :     * The next seed for default constructors.
181 :     */
182 :     private static final AtomicLong defaultSeedGenerator =
183 :     new AtomicLong(System.nanoTime());
184 :    
185 :     /**
186 :     * The seed, updated only via method nextSeed.
187 :     */
188 :     private long seed;
189 :    
190 :     /**
191 :     * The constant value added to seed (mod George) on each update.
192 :     */
193 :     private final long gamma;
194 :    
195 :     /**
196 :     * The next seed to use for splits. Propagated using
197 :     * addGammaModGeorge across instances.
198 :     */
199 :     private final long nextSplit;
200 :    
201 :     /**
202 :     * Internal constructor used by all other constructors and by
203 :     * method split. Establishes the initial seed for this instance,
204 :     * and uses the given splitSeed to establish gamma, as well as the
205 :     * nextSplit to use by this instance.
206 :     */
207 :     private SplittableRandom(long seed, long splitSeed) {
208 :     this.seed = seed;
209 :     long s = splitSeed, g;
210 :     do { // ensure gamma >= 13, considered as an unsigned integer
211 :     s = addGammaModGeorge(s, GAMMA_GAMMA);
212 :     g = mix64(s);
213 :     } while (Long.compareUnsigned(g, 13L) < 0);
214 :     this.gamma = g;
215 :     this.nextSplit = s;
216 :     }
217 :    
218 :     /**
219 :     * Adds the given gamma value, g, to the given seed value s, mod
220 :     * George (2^64+13). We regard s and g as unsigned values
221 :     * (ranging from 0 to 2^64-1). We add g to s either once or twice
222 :     * (mod George) as necessary to produce an (unsigned) result less
223 :     * than 2^64. We require that g must be at least 13. This
224 :     * guarantees that if (s+g) mod George >= 2^64 then (s+g+g) mod
225 :     * George < 2^64; thus we need only a conditional, not a loop,
226 :     * to be sure of getting a representable value.
227 :     *
228 :     * @param s a seed value
229 :     * @param g a gamma value, 13 <= g (as unsigned)
230 :     */
231 :     private static long addGammaModGeorge(long s, long g) {
232 :     long p = s + g;
233 :     if (Long.compareUnsigned(p, g) >= 0)
234 :     return p;
235 :     long q = p - 13L;
236 :     return (Long.compareUnsigned(p, 13L) >= 0) ? q : (q + g);
237 :     }
238 :    
239 :     /**
240 :     * Updates in-place and returns seed.
241 :     * See above for explanation.
242 :     */
243 :     private long nextSeed() {
244 :     return seed = addGammaModGeorge(seed, gamma);
245 :     }
246 :    
247 :     /**
248 :     * Returns a bit-mixed transformation of its argument.
249 :     * See above for explanation.
250 :     */
251 :     private static long mix64(long z) {
252 :     z ^= (z >>> 33);
253 :     z *= 0xff51afd7ed558ccdL;
254 :     z ^= (z >>> 33);
255 :     z *= 0xc4ceb9fe1a85ec53L;
256 :     z ^= (z >>> 33);
257 :     return z;
258 :     }
259 :    
260 :     /**
261 :     * Returns a bit-mixed int transformation of its argument.
262 :     * See above for explanation.
263 :     */
264 :     private static int mix32(long z) {
265 :     z ^= (z >>> 33);
266 :     z *= 0xc4ceb9fe1a85ec53L;
267 :     return (int)(z >>> 32);
268 :     }
269 :    
270 :     /**
271 :     * Atomically updates and returns next seed for default constructor
272 :     */
273 :     private static long nextDefaultSeed() {
274 :     long oldSeed, newSeed;
275 :     do {
276 :     oldSeed = defaultSeedGenerator.get();
277 :     newSeed = addGammaModGeorge(oldSeed, DEFAULT_SEED_GAMMA);
278 :     } while (!defaultSeedGenerator.compareAndSet(oldSeed, newSeed));
279 :     return mix64(newSeed);
280 :     }
281 :    
282 :     /*
283 :     * Internal versions of nextX methods used by streams, as well as
284 :     * the public nextX(origin, bound) methods. These exist mainly to
285 :     * avoid the need for multiple versions of stream spliterators
286 :     * across the different exported forms of streams.
287 :     */
288 :    
289 :     /**
290 :     * The form of nextLong used by LongStream Spliterators. If
291 :     * origin is greater than bound, acts as unbounded form of
292 :     * nextLong, else as bounded form.
293 :     *
294 :     * @param origin the least value, unless greater than bound
295 :     * @param bound the upper bound (exclusive), must not equal origin
296 :     * @return a pseudorandom value
297 :     */
298 :     final long internalNextLong(long origin, long bound) {
299 :     /*
300 :     * Four Cases:
301 :     *
302 :     * 1. If the arguments indicate unbounded form, act as
303 :     * nextLong().
304 :     *
305 :     * 2. If the range is an exact power of two, apply the
306 :     * associated bit mask.
307 :     *
308 :     * 3. If the range is positive, loop to avoid potential bias
309 :     * when the implicit nextLong() bound (2<sup>64</sup>) is not
310 :     * evenly divisible by the range. The loop rejects candidates
311 :     * computed from otherwise over-represented values. The
312 :     * expected number of iterations under an ideal generator
313 :     * varies from 1 to 2, depending on the bound.
314 :     *
315 :     * 4. Otherwise, the range cannot be represented as a positive
316 :     * long. Repeatedly generate unbounded longs until obtaining
317 :     * a candidate meeting constraints (with an expected number of
318 :     * iterations of less than two).
319 :     */
320 :    
321 :     long r = mix64(nextSeed());
322 :     if (origin < bound) {
323 :     long n = bound - origin, m = n - 1;
324 :     if ((n & m) == 0L) // power of two
325 :     r = (r & m) + origin;
326 :     else if (n > 0) { // reject over-represented candidates
327 :     for (long u = r >>> 1; // ensure nonnegative
328 :     u + m - (r = u % n) < 0L; // reject
329 :     u = mix64(nextSeed()) >>> 1) // retry
330 :     ;
331 :     r += origin;
332 :     }
333 :     else { // range not representable as long
334 :     while (r < origin || r >= bound)
335 :     r = mix64(nextSeed());
336 :     }
337 :     }
338 :     return r;
339 :     }
340 :    
341 :     /**
342 :     * The form of nextInt used by IntStream Spliterators.
343 :     * Exactly the same as long version, except for types.
344 :     *
345 :     * @param origin the least value, unless greater than bound
346 :     * @param bound the upper bound (exclusive), must not equal origin
347 :     * @return a pseudorandom value
348 :     */
349 :     final int internalNextInt(int origin, int bound) {
350 :     int r = mix32(nextSeed());
351 :     if (origin < bound) {
352 :     int n = bound - origin, m = n - 1;
353 :     if ((n & m) == 0L)
354 :     r = (r & m) + origin;
355 :     else if (n > 0) {
356 :     for (int u = r >>> 1;
357 :     u + m - (r = u % n) < 0L;
358 :     u = mix32(nextSeed()) >>> 1)
359 :     ;
360 :     r += origin;
361 :     }
362 :     else {
363 :     while (r < origin || r >= bound)
364 :     r = mix32(nextSeed());
365 :     }
366 :     }
367 :     return r;
368 :     }
369 :    
370 :     /**
371 :     * The form of nextDouble used by DoubleStream Spliterators.
372 :     *
373 :     * @param origin the least value, unless greater than bound
374 :     * @param bound the upper bound (exclusive), must not equal origin
375 :     * @return a pseudorandom value
376 :     */
377 :     final double internalNextDouble(double origin, double bound) {
378 :     long bits = (1023L << 52) | (nextLong() >>> 12);
379 :     double r = Double.longBitsToDouble(bits) - 1.0;
380 :     if (origin < bound) {
381 :     r = r * (bound - origin) + origin;
382 :     if (r == bound) // correct for rounding
383 :     r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
384 :     }
385 :     return r;
386 :     }
387 :    
388 :     /* ---------------- public methods ---------------- */
389 :    
390 :     /**
391 :     * Creates a new SplittableRandom instance using the given initial
392 :     * seed. Two SplittableRandom instances created with the same seed
393 :     * generate identical sequences of values.
394 :     *
395 :     * @param seed the initial seed
396 :     */
397 :     public SplittableRandom(long seed) {
398 :     this(seed, 0);
399 :     }
400 :    
401 :     /**
402 :     * Creates a new SplittableRandom instance that is likely to
403 :     * generate sequences of values that are statistically independent
404 :     * of those of any other instances in the current program; and
405 :     * may, and typically does, vary across program invocations.
406 :     */
407 :     public SplittableRandom() {
408 :     this(nextDefaultSeed(), GAMMA_GAMMA);
409 :     }
410 :    
411 :     /**
412 :     * Constructs and returns a new SplittableRandom instance that
413 :     * shares no mutable state with this instance. However, with very
414 :     * high probability, the set of values collectively generated by
415 :     * the two objects has the same statistical properties as if the
416 :     * same quantity of values were generated by a single thread using
417 :     * a single SplittableRandom object. Either or both of the two
418 :     * objects may be further split using the {@code split()} method,
419 :     * and the same expected statistical properties apply to the
420 :     * entire set of generators constructed by such recursive
421 :     * splitting.
422 :     *
423 :     * @return the new SplittableRandom instance
424 :     */
425 :     public SplittableRandom split() {
426 :     return new SplittableRandom(nextSeed(), nextSplit);
427 :     }
428 :    
429 :     /**
430 :     * Returns a pseudorandom {@code int} value.
431 :     *
432 :     * @return a pseudorandom value
433 :     */
434 :     public int nextInt() {
435 :     return mix32(nextSeed());
436 :     }
437 :    
438 :     /**
439 :     * Returns a pseudorandom {@code int} value between 0 (inclusive)
440 :     * and the specified bound (exclusive).
441 :     *
442 :     * @param bound the bound on the random number to be returned. Must be
443 :     * positive.
444 :     * @return a pseudorandom {@code int} value between {@code 0}
445 :     * (inclusive) and the bound (exclusive).
446 :     * @exception IllegalArgumentException if the bound is not positive
447 :     */
448 :     public int nextInt(int bound) {
449 :     if (bound <= 0)
450 :     throw new IllegalArgumentException("bound must be positive");
451 :     // Specialize internalNextInt for origin 0
452 :     int r = mix32(nextSeed());
453 :     int m = bound - 1;
454 :     if ((bound & m) == 0L) // power of two
455 :     r &= m;
456 :     else { // reject over-represented candidates
457 :     for (int u = r >>> 1;
458 :     u + m - (r = u % bound) < 0L;
459 :     u = mix32(nextSeed()) >>> 1)
460 :     ;
461 :     }
462 :     return r;
463 :     }
464 :    
465 :     /**
466 :     * Returns a pseudorandom {@code int} value between the specified
467 :     * origin (inclusive) and the specified bound (exclusive).
468 :     *
469 :     * @param origin the least value returned
470 :     * @param bound the upper bound (exclusive)
471 :     * @return a pseudorandom {@code int} value between the origin
472 :     * (inclusive) and the bound (exclusive).
473 :     * @exception IllegalArgumentException if {@code origin} is greater than
474 :     * or equal to {@code bound}
475 :     */
476 :     public int nextInt(int origin, int bound) {
477 :     if (origin >= bound)
478 :     throw new IllegalArgumentException("bound must be greater than origin");
479 :     return internalNextInt(origin, bound);
480 :     }
481 :    
482 :     /**
483 :     * Returns a pseudorandom {@code long} value.
484 :     *
485 :     * @return a pseudorandom value
486 :     */
487 :     public long nextLong() {
488 :     return mix64(nextSeed());
489 :     }
490 :    
491 :     /**
492 :     * Returns a pseudorandom {@code long} value between 0 (inclusive)
493 :     * and the specified bound (exclusive).
494 :     *
495 :     * @param bound the bound on the random number to be returned. Must be
496 :     * positive.
497 :     * @return a pseudorandom {@code long} value between {@code 0}
498 :     * (inclusive) and the bound (exclusive).
499 :     * @exception IllegalArgumentException if the bound is not positive
500 :     */
501 :     public long nextLong(long bound) {
502 :     if (bound <= 0)
503 :     throw new IllegalArgumentException("bound must be positive");
504 :     // Specialize internalNextLong for origin 0
505 :     long r = mix64(nextSeed());
506 :     long m = bound - 1;
507 :     if ((bound & m) == 0L) // power of two
508 :     r &= m;
509 :     else { // reject over-represented candidates
510 :     for (long u = r >>> 1;
511 :     u + m - (r = u % bound) < 0L;
512 :     u = mix64(nextSeed()) >>> 1)
513 :     ;
514 :     }
515 :     return r;
516 :     }
517 :    
518 :     /**
519 :     * Returns a pseudorandom {@code long} value between the specified
520 :     * origin (inclusive) and the specified bound (exclusive).
521 :     *
522 :     * @param origin the least value returned
523 :     * @param bound the upper bound (exclusive)
524 :     * @return a pseudorandom {@code long} value between the origin
525 :     * (inclusive) and the bound (exclusive).
526 :     * @exception IllegalArgumentException if {@code origin} is greater than
527 :     * or equal to {@code bound}
528 :     */
529 :     public long nextLong(long origin, long bound) {
530 :     if (origin >= bound)
531 :     throw new IllegalArgumentException("bound must be greater than origin");
532 :     return internalNextLong(origin, bound);
533 :     }
534 :    
535 :     /**
536 :     * Returns a pseudorandom {@code double} value between {@code 0.0}
537 :     * (inclusive) and {@code 1.0} (exclusive).
538 :     *
539 :     * @return a pseudorandom value between {@code 0.0}
540 :     * (inclusive) and {@code 1.0} (exclusive)
541 :     */
542 :     public double nextDouble() {
543 :     long bits = (1023L << 52) | (nextLong() >>> 12);
544 :     return Double.longBitsToDouble(bits) - 1.0;
545 :     }
546 :    
547 :     /**
548 :     * Returns a pseudorandom {@code double} value between 0.0
549 :     * (inclusive) and the specified bound (exclusive).
550 :     *
551 :     * @param bound the bound on the random number to be returned. Must be
552 :     * positive.
553 :     * @return a pseudorandom {@code double} value between {@code 0.0}
554 :     * (inclusive) and the bound (exclusive).
555 :     * @throws IllegalArgumentException if {@code bound} is not positive
556 :     */
557 :     public double nextDouble(double bound) {
558 :     if (bound <= 0.0)
559 :     throw new IllegalArgumentException("bound must be positive");
560 :     double result = nextDouble() * bound;
561 :     return (result < bound) ? result : // correct for rounding
562 :     Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
563 :     }
564 :    
565 :     /**
566 :     * Returns a pseudorandom {@code double} value between the given
567 :     * origin (inclusive) and bound (exclusive).
568 :     *
569 :     * @param origin the least value returned
570 :     * @param bound the upper bound
571 :     * @return a pseudorandom {@code double} value between the origin
572 :     * (inclusive) and the bound (exclusive).
573 :     * @throws IllegalArgumentException if {@code origin} is greater than
574 :     * or equal to {@code bound}
575 :     */
576 :     public double nextDouble(double origin, double bound) {
577 :     if (origin >= bound)
578 :     throw new IllegalArgumentException("bound must be greater than origin");
579 :     return internalNextDouble(origin, bound);
580 :     }
581 :    
582 :     // stream methods, coded in a way intended to better isolate for
583 :     // maintenance purposes the small differences across forms.
584 :    
585 :     /**
586 :     * Returns a stream with the given {@code streamSize} number of
587 :     * pseudorandom {@code int} values.
588 :     *
589 :     * @param streamSize the number of values to generate
590 :     * @return a stream of pseudorandom {@code int} values
591 :     * @throws IllegalArgumentException if {@code streamSize} is
592 :     * less than zero
593 :     */
594 :     public IntStream ints(long streamSize) {
595 :     if (streamSize < 0L)
596 :     throw new IllegalArgumentException("negative Stream size");
597 :     return StreamSupport.intStream
598 :     (new RandomIntsSpliterator
599 :     (this, 0L, streamSize, Integer.MAX_VALUE, 0),
600 :     false);
601 :     }
602 :    
603 :     /**
604 :     * Returns an effectively unlimited stream of pseudorandom {@code int}
605 :     * values
606 :     *
607 :     * @implNote This method is implemented to be equivalent to {@code
608 :     * ints(Long.MAX_VALUE)}.
609 :     *
610 :     * @return a stream of pseudorandom {@code int} values
611 :     */
612 :     public IntStream ints() {
613 :     return StreamSupport.intStream
614 :     (new RandomIntsSpliterator
615 :     (this, 0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0),
616 :     false);
617 :     }
618 :    
619 :     /**
620 :     * Returns a stream with the given {@code streamSize} number of
621 :     * pseudorandom {@code int} values, each conforming to the given
622 :     * origin and bound.
623 :     *
624 :     * @param streamSize the number of values to generate
625 :     * @param randomNumberOrigin the origin of each random value
626 :     * @param randomNumberBound the bound of each random value
627 :     * @return a stream of pseudorandom {@code int} values,
628 :     * each with the given origin and bound.
629 :     * @throws IllegalArgumentException if {@code streamSize} is
630 :     * less than zero.
631 :     * @throws IllegalArgumentException if {@code randomNumberOrigin}
632 :     * is greater than or equal to {@code randomNumberBound}
633 :     */
634 :     public IntStream ints(long streamSize, int randomNumberOrigin,
635 :     int randomNumberBound) {
636 :     if (streamSize < 0L)
637 :     throw new IllegalArgumentException("negative Stream size");
638 :     if (randomNumberOrigin >= randomNumberBound)
639 :     throw new IllegalArgumentException("bound must be greater than origin");
640 :     return StreamSupport.intStream
641 :     (new RandomIntsSpliterator
642 :     (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
643 :     false);
644 :     }
645 :    
646 :     /**
647 :     * Returns an effectively unlimited stream of pseudorandom {@code
648 :     * int} values, each conforming to the given origin and bound.
649 :     *
650 :     * @implNote This method is implemented to be equivalent to {@code
651 :     * ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
652 :     *
653 :     * @param randomNumberOrigin the origin of each random value
654 :     * @param randomNumberBound the bound of each random value
655 :     * @return a stream of pseudorandom {@code int} values,
656 :     * each with the given origin and bound.
657 :     * @throws IllegalArgumentException if {@code randomNumberOrigin}
658 :     * is greater than or equal to {@code randomNumberBound}
659 :     */
660 :     public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
661 :     if (randomNumberOrigin >= randomNumberBound)
662 :     throw new IllegalArgumentException("bound must be greater than origin");
663 :     return StreamSupport.intStream
664 :     (new RandomIntsSpliterator
665 :     (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
666 :     false);
667 :     }
668 :    
669 :     /**
670 :     * Returns a stream with the given {@code streamSize} number of
671 :     * pseudorandom {@code long} values.
672 :     *
673 :     * @param streamSize the number of values to generate
674 :     * @return a stream of {@code long} values
675 :     * @throws IllegalArgumentException if {@code streamSize} is
676 :     * less than zero
677 :     */
678 :     public LongStream longs(long streamSize) {
679 :     if (streamSize < 0L)
680 :     throw new IllegalArgumentException("negative Stream size");
681 :     return StreamSupport.longStream
682 :     (new RandomLongsSpliterator
683 :     (this, 0L, streamSize, Long.MAX_VALUE, 0L),
684 :     false);
685 :     }
686 :    
687 :     /**
688 :     * Returns an effectively unlimited stream of pseudorandom {@code long}
689 :     * values.
690 :     *
691 :     * @implNote This method is implemented to be equivalent to {@code
692 :     * longs(Long.MAX_VALUE)}.
693 :     *
694 :     * @return a stream of pseudorandom {@code long} values
695 :     */
696 :     public LongStream longs() {
697 :     return StreamSupport.longStream
698 :     (new RandomLongsSpliterator
699 :     (this, 0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L),
700 :     false);
701 :     }
702 :    
703 :     /**
704 :     * Returns a stream with the given {@code streamSize} number of
705 :     * pseudorandom {@code long} values, each conforming to the
706 :     * given origin and bound.
707 :     *
708 :     * @param streamSize the number of values to generate
709 :     * @param randomNumberOrigin the origin of each random value
710 :     * @param randomNumberBound the bound of each random value
711 :     * @return a stream of pseudorandom {@code long} values,
712 :     * each with the given origin and bound.
713 :     * @throws IllegalArgumentException if {@code streamSize} is
714 :     * less than zero.
715 :     * @throws IllegalArgumentException if {@code randomNumberOrigin}
716 :     * is greater than or equal to {@code randomNumberBound}
717 :     */
718 :     public LongStream longs(long streamSize, long randomNumberOrigin,
719 :     long randomNumberBound) {
720 :     if (streamSize < 0L)
721 :     throw new IllegalArgumentException("negative Stream size");
722 :     if (randomNumberOrigin >= randomNumberBound)
723 :     throw new IllegalArgumentException("bound must be greater than origin");
724 :     return StreamSupport.longStream
725 :     (new RandomLongsSpliterator
726 :     (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
727 :     false);
728 :     }
729 :    
730 :     /**
731 :     * Returns an effectively unlimited stream of pseudorandom {@code
732 :     * long} values, each conforming to the given origin and bound.
733 :     *
734 :     * @implNote This method is implemented to be equivalent to {@code
735 :     * longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
736 :     *
737 :     * @param randomNumberOrigin the origin of each random value
738 :     * @param randomNumberBound the bound of each random value
739 :     * @return a stream of pseudorandom {@code long} values,
740 :     * each with the given origin and bound.
741 :     * @throws IllegalArgumentException if {@code randomNumberOrigin}
742 :     * is greater than or equal to {@code randomNumberBound}
743 :     */
744 :     public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
745 :     if (randomNumberOrigin >= randomNumberBound)
746 :     throw new IllegalArgumentException("bound must be greater than origin");
747 :     return StreamSupport.longStream
748 :     (new RandomLongsSpliterator
749 :     (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
750 :     false);
751 :     }
752 :    
753 :     /**
754 :     * Returns a stream with the given {@code streamSize} number of
755 :     * pseudorandom {@code double} values.
756 :     *
757 :     * @param streamSize the number of values to generate
758 :     * @return a stream of {@code double} values
759 :     * @throws IllegalArgumentException if {@code streamSize} is
760 :     * less than zero
761 :     */
762 :     public DoubleStream doubles(long streamSize) {
763 :     if (streamSize < 0L)
764 :     throw new IllegalArgumentException("negative Stream size");
765 :     return StreamSupport.doubleStream
766 :     (new RandomDoublesSpliterator
767 :     (this, 0L, streamSize, Double.MAX_VALUE, 0.0),
768 :     false);
769 :     }
770 :    
771 :     /**
772 :     * Returns an effectively unlimited stream of pseudorandom {@code
773 :     * double} values.
774 :     *
775 :     * @implNote This method is implemented to be equivalent to {@code
776 :     * doubles(Long.MAX_VALUE)}.
777 :     *
778 :     * @return a stream of pseudorandom {@code double} values
779 :     */
780 :     public DoubleStream doubles() {
781 :     return StreamSupport.doubleStream
782 :     (new RandomDoublesSpliterator
783 :     (this, 0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0),
784 :     false);
785 :     }
786 :    
787 :     /**
788 :     * Returns a stream with the given {@code streamSize} number of
789 :     * pseudorandom {@code double} values, each conforming to the
790 :     * given origin and bound.
791 :     *
792 :     * @param streamSize the number of values to generate
793 :     * @param randomNumberOrigin the origin of each random value
794 :     * @param randomNumberBound the bound of each random value
795 :     * @return a stream of pseudorandom {@code double} values,
796 :     * each with the given origin and bound.
797 :     * @throws IllegalArgumentException if {@code streamSize} is
798 :     * less than zero.
799 :     * @throws IllegalArgumentException if {@code randomNumberOrigin}
800 :     * is greater than or equal to {@code randomNumberBound}
801 :     */
802 :     public DoubleStream doubles(long streamSize, double randomNumberOrigin,
803 :     double randomNumberBound) {
804 :     if (streamSize < 0L)
805 :     throw new IllegalArgumentException("negative Stream size");
806 :     if (randomNumberOrigin >= randomNumberBound)
807 :     throw new IllegalArgumentException("bound must be greater than origin");
808 :     return StreamSupport.doubleStream
809 :     (new RandomDoublesSpliterator
810 :     (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
811 :     false);
812 :     }
813 :    
814 :     /**
815 :     * Returns an effectively unlimited stream of pseudorandom {@code
816 :     * double} values, each conforming to the given origin and bound.
817 :     *
818 :     * @implNote This method is implemented to be equivalent to {@code
819 :     * doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
820 :     *
821 :     * @param randomNumberOrigin the origin of each random value
822 :     * @param randomNumberBound the bound of each random value
823 :     * @return a stream of pseudorandom {@code double} values,
824 :     * each with the given origin and bound.
825 :     * @throws IllegalArgumentException if {@code randomNumberOrigin}
826 :     * is greater than or equal to {@code randomNumberBound}
827 :     */
828 :     public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
829 :     if (randomNumberOrigin >= randomNumberBound)
830 :     throw new IllegalArgumentException("bound must be greater than origin");
831 :     return StreamSupport.doubleStream
832 :     (new RandomDoublesSpliterator
833 :     (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
834 :     false);
835 :     }
836 :    
837 :     /**
838 :     * Spliterator for int streams. We multiplex the four int
839 :     * versions into one class by treating and bound < origin as
840 :     * unbounded, and also by treating "infinite" as equivalent to
841 :     * Long.MAX_VALUE. For splits, it uses the standard divide-by-two
842 :     * approach. The long and double versions of this class are
843 :     * identical except for types.
844 :     */
845 :     static class RandomIntsSpliterator implements Spliterator.OfInt {
846 :     final SplittableRandom rng;
847 :     long index;
848 :     final long fence;
849 :     final int origin;
850 :     final int bound;
851 :     RandomIntsSpliterator(SplittableRandom rng, long index, long fence,
852 :     int origin, int bound) {
853 :     this.rng = rng; this.index = index; this.fence = fence;
854 :     this.origin = origin; this.bound = bound;
855 :     }
856 :    
857 :     public RandomIntsSpliterator trySplit() {
858 :     long i = index, m = (i + fence) >>> 1;
859 :     return (m <= i) ? null :
860 :     new RandomIntsSpliterator(rng.split(), i, index = m, origin, bound);
861 :     }
862 :    
863 :     public long estimateSize() {
864 :     return fence - index;
865 :     }
866 :    
867 :     public int characteristics() {
868 :     return (Spliterator.SIZED | Spliterator.SUBSIZED |
869 :     Spliterator.ORDERED | Spliterator.NONNULL |
870 :     Spliterator.IMMUTABLE);
871 :     }
872 :    
873 :     public boolean tryAdvance(IntConsumer consumer) {
874 :     if (consumer == null) throw new NullPointerException();
875 :     long i = index, f = fence;
876 :     if (i < f) {
877 :     consumer.accept(rng.internalNextInt(origin, bound));
878 :     index = i + 1;
879 :     return true;
880 :     }
881 :     return false;
882 :     }
883 :    
884 :     public void forEachRemaining(IntConsumer consumer) {
885 :     if (consumer == null) throw new NullPointerException();
886 :     long i = index, f = fence;
887 :     if (i < f) {
888 :     index = f;
889 :     int o = origin, b = bound;
890 :     do {
891 :     consumer.accept(rng.internalNextInt(o, b));
892 :     } while (++i < f);
893 :     }
894 :     }
895 :     }
896 :    
897 :     /**
898 :     * Spliterator for long streams.
899 :     */
900 :     static class RandomLongsSpliterator implements Spliterator.OfLong {
901 :     final SplittableRandom rng;
902 :     long index;
903 :     final long fence;
904 :     final long origin;
905 :     final long bound;
906 :     RandomLongsSpliterator(SplittableRandom rng, long index, long fence,
907 :     long origin, long bound) {
908 :     this.rng = rng; this.index = index; this.fence = fence;
909 :     this.origin = origin; this.bound = bound;
910 :     }
911 :    
912 :     public RandomLongsSpliterator trySplit() {
913 :     long i = index, m = (i + fence) >>> 1;
914 :     return (m <= i) ? null :
915 :     new RandomLongsSpliterator(rng.split(), i, index = m, origin, bound);
916 :     }
917 :    
918 :     public long estimateSize() {
919 :     return fence - index;
920 :     }
921 :    
922 :     public int characteristics() {
923 :     return (Spliterator.SIZED | Spliterator.SUBSIZED |
924 :     Spliterator.ORDERED | Spliterator.NONNULL |
925 :     Spliterator.IMMUTABLE);
926 :     }
927 :    
928 :     public boolean tryAdvance(LongConsumer consumer) {
929 :     if (consumer == null) throw new NullPointerException();
930 :     long i = index, f = fence;
931 :     if (i < f) {
932 :     consumer.accept(rng.internalNextLong(origin, bound));
933 :     index = i + 1;
934 :     return true;
935 :     }
936 :     return false;
937 :     }
938 :    
939 :     public void forEachRemaining(LongConsumer consumer) {
940 :     if (consumer == null) throw new NullPointerException();
941 :     long i = index, f = fence;
942 :     if (i < f) {
943 :     index = f;
944 :     long o = origin, b = bound;
945 :     do {
946 :     consumer.accept(rng.internalNextLong(o, b));
947 :     } while (++i < f);
948 :     }
949 :     }
950 :    
951 :     }
952 :    
953 :     /**
954 :     * Spliterator for double streams.
955 :     */
956 :     static class RandomDoublesSpliterator implements Spliterator.OfDouble {
957 :     final SplittableRandom rng;
958 :     long index;
959 :     final long fence;
960 :     final double origin;
961 :     final double bound;
962 :     RandomDoublesSpliterator(SplittableRandom rng, long index, long fence,
963 :     double origin, double bound) {
964 :     this.rng = rng; this.index = index; this.fence = fence;
965 :     this.origin = origin; this.bound = bound;
966 :     }
967 :    
968 :     public RandomDoublesSpliterator trySplit() {
969 :     long i = index, m = (i + fence) >>> 1;
970 :     return (m <= i) ? null :
971 :     new RandomDoublesSpliterator(rng.split(), i, index = m, origin, bound);
972 :     }
973 :    
974 :     public long estimateSize() {
975 :     return fence - index;
976 :     }
977 :    
978 :     public int characteristics() {
979 :     return (Spliterator.SIZED | Spliterator.SUBSIZED |
980 :     Spliterator.ORDERED | Spliterator.NONNULL |
981 :     Spliterator.IMMUTABLE);
982 :     }
983 :    
984 :     public boolean tryAdvance(DoubleConsumer consumer) {
985 :     if (consumer == null) throw new NullPointerException();
986 :     long i = index, f = fence;
987 :     if (i < f) {
988 :     consumer.accept(rng.internalNextDouble(origin, bound));
989 :     index = i + 1;
990 :     return true;
991 :     }
992 :     return false;
993 :     }
994 :    
995 :     public void forEachRemaining(DoubleConsumer consumer) {
996 :     if (consumer == null) throw new NullPointerException();
997 :     long i = index, f = fence;
998 :     if (i < f) {
999 :     index = f;
1000 :     double o = origin, b = bound;
1001 :     do {
1002 :     consumer.accept(rng.internalNextDouble(o, b));
1003 :     } while (++i < f);
1004 :     }
1005 :     }
1006 :     }
1007 :    
1008 :     }
1009 :    

Doug Lea
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