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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 : dl 1.15 import java.net.InetAddress;
29 : dl 1.1 import java.util.concurrent.atomic.AtomicLong;
30 :     import java.util.Spliterator;
31 :     import java.util.function.IntConsumer;
32 :     import java.util.function.LongConsumer;
33 :     import java.util.function.DoubleConsumer;
34 :     import java.util.stream.StreamSupport;
35 :     import java.util.stream.IntStream;
36 :     import java.util.stream.LongStream;
37 :     import java.util.stream.DoubleStream;
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 : jsr166 1.3 * producing pseudorandom numbers of type {@code int}, {@code long},
44 : dl 1.1 * and {@code double} with similar usages as for class
45 : jsr166 1.9 * {@link java.util.Random} but differs in the following ways:
46 :     *
47 :     * <ul>
48 : dl 1.1 *
49 :     * <li>Series of generated values pass the DieHarder suite testing
50 :     * independence and uniformity properties of random number generators.
51 :     * (Most recently validated with <a
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 : dl 1.11 * 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 : dl 1.1 *
59 :     * <li> Method {@link #split} constructs and returns a new
60 :     * SplittableRandom instance that shares no mutable state with the
61 : dl 1.7 * current instance. However, with very high probability, the
62 :     * values collectively generated by the two objects have the same
63 : dl 1.1 * statistical properties as if the same quantity of values were
64 :     * generated by a single thread using a single {@code
65 :     * SplittableRandom} object. </li>
66 :     *
67 :     * <li>Instances of SplittableRandom are <em>not</em> thread-safe.
68 :     * They are designed to be split, not shared, across threads. For
69 :     * example, a {@link java.util.concurrent.ForkJoinTask
70 :     * fork/join-style} computation using random numbers might include a
71 :     * construction of the form {@code new
72 :     * Subtask(aSplittableRandom.split()).fork()}.
73 :     *
74 :     * <li>This class provides additional methods for generating random
75 :     * streams, that employ the above techniques when used in {@code
76 :     * stream.parallel()} mode.</li>
77 :     *
78 :     * </ul>
79 :     *
80 :     * @author Guy Steele
81 : dl 1.2 * @author Doug Lea
82 : dl 1.1 * @since 1.8
83 :     */
84 :     public class SplittableRandom {
85 :    
86 :     /*
87 :     * Implementation Overview.
88 :     *
89 :     * This algorithm was inspired by the "DotMix" algorithm by
90 :     * Leiserson, Schardl, and Sukha "Deterministic Parallel
91 :     * Random-Number Generation for Dynamic-Multithreading Platforms",
92 : dl 1.15 * PPoPP 2012, as well as those in "Parallel random numbers: as
93 :     * easy as 1, 2, 3" by Salmon, Morae, Dror, and Shaw, SC 2011. It
94 :     * differs mainly in simplifying and cheapening operations.
95 :     *
96 :     * The primary update step (method nextSeed()) is to add a
97 :     * constant ("gamma") to the current (64 bit) seed, forming a
98 :     * simple sequence. The seed and the gamma values for any two
99 :     * SplittableRandom instances are highly likely to be different.
100 :     *
101 :     * Methods nextLong, nextInt, and derivatives do not return the
102 :     * sequence (seed) values, but instead a hash-like bit-mix of
103 :     * their bits, producing more independently distributed sequences.
104 :     * For nextLong, the mix64 bit-mixing function computes the same
105 :     * value as the "64-bit finalizer" function in Austin Appleby's
106 :     * MurmurHash3 algorithm. See
107 : dl 1.1 * http://code.google.com/p/smhasher/wiki/MurmurHash3 , which
108 :     * comments: "The constants for the finalizers were generated by a
109 :     * simple simulated-annealing algorithm, and both avalanche all
110 : dl 1.15 * bits of 'h' to within 0.25% bias." The mix32 function is
111 :     * equivalent to (int)(mix64(seed) >>> 32), but faster because it
112 :     * omits a step that doesn't contribute to result.
113 :     *
114 :     * The split operation uses the current generator to form the seed
115 :     * and gamma for another SplittableRandom. To conservatively
116 :     * avoid potential correlations between seed and value generation,
117 :     * gamma selection (method nextGamma) uses the "Mix13" constants
118 :     * for MurmurHash3 described by David Stafford
119 :     * (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html)
120 :     * To avoid potential weaknesses in bit-mixing transformations, we
121 :     * restrict gammas to odd values with at least 12 and no more than
122 :     * 52 bits set. Rather than rejecting candidates with too few or
123 :     * too many bits set, method nextGamma flips some bits (which has
124 :     * the effect of mapping at most 4 to any given gamma value).
125 :     * This reduces the effective set of 64bit odd gamma values by
126 :     * about 2<sup>14</sup>, a very tiny percentage, and serves as an
127 :     * automated screening for sequence constant selection that is
128 :     * left as an empirical decision in some other hashing and crypto
129 :     * algorithms.
130 :     *
131 :     * The resulting generator thus transforms a sequence in which
132 :     * (typically) many bits change on each step, with an inexpensive
133 :     * mixer with good (but less than cryptographically secure)
134 :     * avalanching.
135 :     *
136 :     * The default (no-argument) constructor, in essence, invokes
137 :     * split() for a common "seeder" SplittableRandom. Unlike other
138 :     * cases, this split must be performed in a thread-safe manner, so
139 :     * we use an AtomicLong to represent the seed rather than use an
140 :     * explicit SplittableRandom. To bootstrap the seeder, we start
141 :     * off using a seed based on current time and host. This serves as
142 :     * a slimmed-down (and insecure) variant of SecureRandom that also
143 :     * avoids stalls that may occur when using /dev/random.
144 :     *
145 :     * It is a relatively simple matter to apply the basic design here
146 :     * to use 128 bit seeds. However, emulating 128bit arithmetic and
147 :     * carrying around twice the state add more overhead than appears
148 :     * warranted for current usages.
149 : dl 1.13 *
150 : dl 1.15 * File organization: First the non-public methods that constitute
151 :     * the main algorithm, then the main public methods, followed by
152 :     * some custom spliterator classes needed for stream methods.
153 : dl 1.1 */
154 :    
155 :     /**
156 : dl 1.15 * The initial gamma value for (unsplit) SplittableRandoms. Must
157 :     * be odd with at least 12 and no more than 52 bits set. Currently
158 :     * set to the golden ratio scaled to 64bits.
159 : dl 1.1 */
160 : dl 1.15 private static final long INITIAL_GAMMA = 0x9e3779b97f4a7c15L;
161 : dl 1.11
162 :     /**
163 : dl 1.5 * The least non-zero value returned by nextDouble(). This value
164 : dl 1.7 * is scaled by a random value of 53 bits to produce a result.
165 : dl 1.5 */
166 :     private static final double DOUBLE_UNIT = 1.0 / (1L << 53);
167 :    
168 :     /**
169 : dl 1.15 * The seed. Updated only via method nextSeed.
170 : dl 1.1 */
171 :     private long seed;
172 :    
173 :     /**
174 : dl 1.15 * The step value.
175 : dl 1.1 */
176 :     private final long gamma;
177 :    
178 :     /**
179 : dl 1.15 * Internal constructor used by all others except default constructor.
180 : dl 1.1 */
181 : dl 1.15 private SplittableRandom(long seed, long gamma) {
182 :     this.seed = seed;
183 :     this.gamma = gamma;
184 : dl 1.1 }
185 :    
186 :     /**
187 : dl 1.15 * Computes MurmurHash3 64bit mix function.
188 : dl 1.1 */
189 :     private static long mix64(long z) {
190 : dl 1.15 z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
191 :     z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
192 :     return z ^ (z >>> 33);
193 : dl 1.1 }
194 :    
195 :     /**
196 : dl 1.15 * Returns the 32 high bits of mix64(z) as int.
197 : dl 1.1 */
198 :     private static int mix32(long z) {
199 : dl 1.15 z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
200 :     return (int)(((z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L) >>> 32);
201 : dl 1.1 }
202 :    
203 :     /**
204 : dl 1.15 * Returns the gamma value to use for a new split instance.
205 : dl 1.13 */
206 : dl 1.15 private static long nextGamma(long z) {
207 :     z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L; // Stafford "Mix13"
208 : dl 1.14 z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
209 : dl 1.15 z = (z ^ (z >>> 31)) | 1L; // force to be odd
210 :     int n = Long.bitCount(z); // ensure enough 0 and 1 bits
211 :     return (n < 12 || n > 52) ? z ^ 0xaaaaaaaaaaaaaaaaL : z;
212 : dl 1.13 }
213 :    
214 :     /**
215 : dl 1.15 * Adds gamma to seed.
216 : dl 1.7 */
217 : dl 1.15 private long nextSeed() {
218 :     return seed += gamma;
219 : dl 1.7 }
220 :    
221 :     /**
222 : dl 1.15 * The seed generator for default constructors.
223 : dl 1.7 */
224 : dl 1.15 private static final AtomicLong seeder =
225 :     new AtomicLong(mix64((((long)hashedHostAddress()) << 32) ^
226 :     System.currentTimeMillis()) ^
227 :     mix64(System.nanoTime()));
228 : dl 1.7
229 :     /**
230 : dl 1.15 * Returns hash of local host IP address, if available; else 0.
231 : dl 1.1 */
232 : dl 1.15 private static int hashedHostAddress() {
233 :     try {
234 :     return InetAddress.getLocalHost().hashCode();
235 :     } catch (Exception ex) {
236 :     return 0;
237 :     }
238 : dl 1.1 }
239 :    
240 : dl 1.15 // IllegalArgumentException messages
241 :     static final String BadBound = "bound must be positive";
242 :     static final String BadRange = "bound must be greater than origin";
243 :     static final String BadSize = "size must be non-negative";
244 : dl 1.12
245 : dl 1.1 /*
246 :     * Internal versions of nextX methods used by streams, as well as
247 :     * the public nextX(origin, bound) methods. These exist mainly to
248 :     * avoid the need for multiple versions of stream spliterators
249 :     * across the different exported forms of streams.
250 :     */
251 :    
252 :     /**
253 :     * The form of nextLong used by LongStream Spliterators. If
254 :     * origin is greater than bound, acts as unbounded form of
255 :     * nextLong, else as bounded form.
256 :     *
257 :     * @param origin the least value, unless greater than bound
258 :     * @param bound the upper bound (exclusive), must not equal origin
259 :     * @return a pseudorandom value
260 :     */
261 :     final long internalNextLong(long origin, long bound) {
262 :     /*
263 :     * Four Cases:
264 :     *
265 :     * 1. If the arguments indicate unbounded form, act as
266 :     * nextLong().
267 :     *
268 :     * 2. If the range is an exact power of two, apply the
269 :     * associated bit mask.
270 :     *
271 :     * 3. If the range is positive, loop to avoid potential bias
272 :     * when the implicit nextLong() bound (2<sup>64</sup>) is not
273 :     * evenly divisible by the range. The loop rejects candidates
274 :     * computed from otherwise over-represented values. The
275 :     * expected number of iterations under an ideal generator
276 : dl 1.4 * varies from 1 to 2, depending on the bound. The loop itself
277 :     * takes an unlovable form. Because the first candidate is
278 :     * already available, we need a break-in-the-middle
279 :     * construction, which is concisely but cryptically performed
280 :     * within the while-condition of a body-less for loop.
281 : dl 1.1 *
282 :     * 4. Otherwise, the range cannot be represented as a positive
283 : dl 1.4 * long. The loop repeatedly generates unbounded longs until
284 :     * obtaining a candidate meeting constraints (with an expected
285 :     * number of iterations of less than two).
286 : dl 1.1 */
287 :    
288 :     long r = mix64(nextSeed());
289 :     if (origin < bound) {
290 :     long n = bound - origin, m = n - 1;
291 : dl 1.7 if ((n & m) == 0L) // power of two
292 : dl 1.1 r = (r & m) + origin;
293 : dl 1.7 else if (n > 0L) { // reject over-represented candidates
294 : dl 1.1 for (long u = r >>> 1; // ensure nonnegative
295 : dl 1.7 u + m - (r = u % n) < 0L; // rejection check
296 : dl 1.1 u = mix64(nextSeed()) >>> 1) // retry
297 :     ;
298 :     r += origin;
299 :     }
300 : dl 1.7 else { // range not representable as long
301 : dl 1.1 while (r < origin || r >= bound)
302 :     r = mix64(nextSeed());
303 :     }
304 :     }
305 :     return r;
306 :     }
307 :    
308 :     /**
309 :     * The form of nextInt used by IntStream Spliterators.
310 :     * Exactly the same as long version, except for types.
311 :     *
312 :     * @param origin the least value, unless greater than bound
313 :     * @param bound the upper bound (exclusive), must not equal origin
314 :     * @return a pseudorandom value
315 :     */
316 :     final int internalNextInt(int origin, int bound) {
317 :     int r = mix32(nextSeed());
318 :     if (origin < bound) {
319 :     int n = bound - origin, m = n - 1;
320 : dl 1.13 if ((n & m) == 0)
321 : dl 1.1 r = (r & m) + origin;
322 :     else if (n > 0) {
323 :     for (int u = r >>> 1;
324 : dl 1.7 u + m - (r = u % n) < 0;
325 : dl 1.1 u = mix32(nextSeed()) >>> 1)
326 :     ;
327 :     r += origin;
328 :     }
329 :     else {
330 :     while (r < origin || r >= bound)
331 :     r = mix32(nextSeed());
332 :     }
333 :     }
334 :     return r;
335 :     }
336 :    
337 :     /**
338 :     * The form of nextDouble used by DoubleStream Spliterators.
339 :     *
340 :     * @param origin the least value, unless greater than bound
341 :     * @param bound the upper bound (exclusive), must not equal origin
342 :     * @return a pseudorandom value
343 :     */
344 :     final double internalNextDouble(double origin, double bound) {
345 : dl 1.5 double r = (nextLong() >>> 11) * DOUBLE_UNIT;
346 : dl 1.1 if (origin < bound) {
347 :     r = r * (bound - origin) + origin;
348 : dl 1.7 if (r >= bound) // correct for rounding
349 : dl 1.1 r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
350 :     }
351 :     return r;
352 :     }
353 :    
354 :     /* ---------------- public methods ---------------- */
355 :    
356 :     /**
357 : dl 1.7 * Creates a new SplittableRandom instance using the specified
358 :     * initial seed. SplittableRandom instances created with the same
359 : dl 1.11 * seed in the same program generate identical sequences of values.
360 : dl 1.1 *
361 :     * @param seed the initial seed
362 :     */
363 :     public SplittableRandom(long seed) {
364 : dl 1.15 this(seed, INITIAL_GAMMA);
365 : dl 1.1 }
366 :    
367 :     /**
368 :     * Creates a new SplittableRandom instance that is likely to
369 :     * generate sequences of values that are statistically independent
370 :     * of those of any other instances in the current program; and
371 :     * may, and typically does, vary across program invocations.
372 :     */
373 : dl 1.15 public SplittableRandom() { // emulate seeder.split()
374 :     this.gamma = nextGamma(this.seed = seeder.addAndGet(INITIAL_GAMMA));
375 : dl 1.1 }
376 :    
377 :     /**
378 :     * Constructs and returns a new SplittableRandom instance that
379 :     * shares no mutable state with this instance. However, with very
380 :     * high probability, the set of values collectively generated by
381 :     * the two objects has the same statistical properties as if the
382 :     * same quantity of values were generated by a single thread using
383 :     * a single SplittableRandom object. Either or both of the two
384 :     * objects may be further split using the {@code split()} method,
385 :     * and the same expected statistical properties apply to the
386 :     * entire set of generators constructed by such recursive
387 :     * splitting.
388 :     *
389 :     * @return the new SplittableRandom instance
390 :     */
391 :     public SplittableRandom split() {
392 : dl 1.15 long s = nextSeed();
393 :     return new SplittableRandom(s, nextGamma(s));
394 : dl 1.1 }
395 :    
396 :     /**
397 :     * Returns a pseudorandom {@code int} value.
398 :     *
399 : dl 1.7 * @return a pseudorandom {@code int} value
400 : dl 1.1 */
401 :     public int nextInt() {
402 :     return mix32(nextSeed());
403 :     }
404 :    
405 :     /**
406 : dl 1.7 * Returns a pseudorandom {@code int} value between zero (inclusive)
407 : dl 1.1 * and the specified bound (exclusive).
408 :     *
409 :     * @param bound the bound on the random number to be returned. Must be
410 :     * positive.
411 : dl 1.7 * @return a pseudorandom {@code int} value between zero
412 : jsr166 1.10 * (inclusive) and the bound (exclusive)
413 : dl 1.7 * @throws IllegalArgumentException if the bound is less than zero
414 : dl 1.1 */
415 :     public int nextInt(int bound) {
416 :     if (bound <= 0)
417 : dl 1.15 throw new IllegalArgumentException(BadBound);
418 : dl 1.1 // Specialize internalNextInt for origin 0
419 :     int r = mix32(nextSeed());
420 :     int m = bound - 1;
421 : dl 1.13 if ((bound & m) == 0) // power of two
422 : dl 1.1 r &= m;
423 :     else { // reject over-represented candidates
424 :     for (int u = r >>> 1;
425 : dl 1.7 u + m - (r = u % bound) < 0;
426 : dl 1.1 u = mix32(nextSeed()) >>> 1)
427 :     ;
428 :     }
429 :     return r;
430 :     }
431 :    
432 :     /**
433 :     * Returns a pseudorandom {@code int} value between the specified
434 :     * origin (inclusive) and the specified bound (exclusive).
435 :     *
436 :     * @param origin the least value returned
437 :     * @param bound the upper bound (exclusive)
438 :     * @return a pseudorandom {@code int} value between the origin
439 : jsr166 1.10 * (inclusive) and the bound (exclusive)
440 : dl 1.7 * @throws IllegalArgumentException if {@code origin} is greater than
441 : dl 1.1 * or equal to {@code bound}
442 :     */
443 :     public int nextInt(int origin, int bound) {
444 :     if (origin >= bound)
445 : dl 1.15 throw new IllegalArgumentException(BadRange);
446 : dl 1.1 return internalNextInt(origin, bound);
447 :     }
448 :    
449 :     /**
450 :     * Returns a pseudorandom {@code long} value.
451 :     *
452 : dl 1.7 * @return a pseudorandom {@code long} value
453 : dl 1.1 */
454 :     public long nextLong() {
455 :     return mix64(nextSeed());
456 :     }
457 :    
458 :     /**
459 : dl 1.7 * Returns a pseudorandom {@code long} value between zero (inclusive)
460 : dl 1.1 * and the specified bound (exclusive).
461 :     *
462 :     * @param bound the bound on the random number to be returned. Must be
463 :     * positive.
464 : dl 1.7 * @return a pseudorandom {@code long} value between zero
465 : jsr166 1.10 * (inclusive) and the bound (exclusive)
466 : dl 1.7 * @throws IllegalArgumentException if {@code bound} is less than zero
467 : dl 1.1 */
468 :     public long nextLong(long bound) {
469 :     if (bound <= 0)
470 : dl 1.15 throw new IllegalArgumentException(BadBound);
471 : dl 1.1 // Specialize internalNextLong for origin 0
472 :     long r = mix64(nextSeed());
473 :     long m = bound - 1;
474 :     if ((bound & m) == 0L) // power of two
475 :     r &= m;
476 :     else { // reject over-represented candidates
477 :     for (long u = r >>> 1;
478 :     u + m - (r = u % bound) < 0L;
479 :     u = mix64(nextSeed()) >>> 1)
480 :     ;
481 :     }
482 :     return r;
483 :     }
484 :    
485 :     /**
486 :     * Returns a pseudorandom {@code long} value between the specified
487 :     * origin (inclusive) and the specified bound (exclusive).
488 :     *
489 :     * @param origin the least value returned
490 :     * @param bound the upper bound (exclusive)
491 :     * @return a pseudorandom {@code long} value between the origin
492 : jsr166 1.10 * (inclusive) and the bound (exclusive)
493 : dl 1.7 * @throws IllegalArgumentException if {@code origin} is greater than
494 : dl 1.1 * or equal to {@code bound}
495 :     */
496 :     public long nextLong(long origin, long bound) {
497 :     if (origin >= bound)
498 : dl 1.15 throw new IllegalArgumentException(BadRange);
499 : dl 1.1 return internalNextLong(origin, bound);
500 :     }
501 :    
502 :     /**
503 : dl 1.7 * Returns a pseudorandom {@code double} value between zero
504 :     * (inclusive) and one (exclusive).
505 : dl 1.1 *
506 : dl 1.7 * @return a pseudorandom {@code double} value between zero
507 :     * (inclusive) and one (exclusive)
508 : dl 1.1 */
509 :     public double nextDouble() {
510 : dl 1.11 return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT;
511 : dl 1.1 }
512 :    
513 :     /**
514 :     * Returns a pseudorandom {@code double} value between 0.0
515 :     * (inclusive) and the specified bound (exclusive).
516 :     *
517 :     * @param bound the bound on the random number to be returned. Must be
518 :     * positive.
519 : dl 1.7 * @return a pseudorandom {@code double} value between zero
520 : jsr166 1.10 * (inclusive) and the bound (exclusive)
521 : dl 1.7 * @throws IllegalArgumentException if {@code bound} is less than zero
522 : dl 1.1 */
523 :     public double nextDouble(double bound) {
524 : dl 1.7 if (!(bound > 0.0))
525 : dl 1.15 throw new IllegalArgumentException(BadBound);
526 : dl 1.11 double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound;
527 : dl 1.1 return (result < bound) ? result : // correct for rounding
528 :     Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
529 :     }
530 :    
531 :     /**
532 : dl 1.7 * Returns a pseudorandom {@code double} value between the specified
533 : dl 1.1 * origin (inclusive) and bound (exclusive).
534 :     *
535 :     * @param origin the least value returned
536 :     * @param bound the upper bound
537 :     * @return a pseudorandom {@code double} value between the origin
538 : jsr166 1.10 * (inclusive) and the bound (exclusive)
539 : dl 1.1 * @throws IllegalArgumentException if {@code origin} is greater than
540 :     * or equal to {@code bound}
541 :     */
542 :     public double nextDouble(double origin, double bound) {
543 : dl 1.7 if (!(origin < bound))
544 : dl 1.15 throw new IllegalArgumentException(BadRange);
545 : dl 1.1 return internalNextDouble(origin, bound);
546 :     }
547 :    
548 : dl 1.11 /**
549 :     * Returns a pseudorandom {@code boolean} value.
550 :     *
551 :     * @return a pseudorandom {@code boolean} value
552 :     */
553 :     public boolean nextBoolean() {
554 :     return mix32(nextSeed()) < 0;
555 :     }
556 :    
557 : dl 1.1 // stream methods, coded in a way intended to better isolate for
558 :     // maintenance purposes the small differences across forms.
559 :    
560 :     /**
561 : dl 1.7 * Returns a stream producing the given {@code streamSize} number of
562 : dl 1.1 * pseudorandom {@code int} values.
563 :     *
564 :     * @param streamSize the number of values to generate
565 :     * @return a stream of pseudorandom {@code int} values
566 :     * @throws IllegalArgumentException if {@code streamSize} is
567 : dl 1.7 * less than zero
568 : dl 1.1 */
569 :     public IntStream ints(long streamSize) {
570 :     if (streamSize < 0L)
571 : dl 1.15 throw new IllegalArgumentException(BadSize);
572 : dl 1.1 return StreamSupport.intStream
573 :     (new RandomIntsSpliterator
574 :     (this, 0L, streamSize, Integer.MAX_VALUE, 0),
575 :     false);
576 :     }
577 :    
578 :     /**
579 :     * Returns an effectively unlimited stream of pseudorandom {@code int}
580 : jsr166 1.10 * values.
581 : dl 1.1 *
582 :     * @implNote This method is implemented to be equivalent to {@code
583 :     * ints(Long.MAX_VALUE)}.
584 :     *
585 :     * @return a stream of pseudorandom {@code int} values
586 :     */
587 :     public IntStream ints() {
588 :     return StreamSupport.intStream
589 :     (new RandomIntsSpliterator
590 :     (this, 0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0),
591 :     false);
592 :     }
593 :    
594 :     /**
595 : dl 1.7 * Returns a stream producing the given {@code streamSize} number of
596 : dl 1.1 * pseudorandom {@code int} values, each conforming to the given
597 :     * origin and bound.
598 :     *
599 :     * @param streamSize the number of values to generate
600 :     * @param randomNumberOrigin the origin of each random value
601 :     * @param randomNumberBound the bound of each random value
602 :     * @return a stream of pseudorandom {@code int} values,
603 : jsr166 1.10 * each with the given origin and bound
604 : dl 1.1 * @throws IllegalArgumentException if {@code streamSize} is
605 : dl 1.7 * less than zero, or {@code randomNumberOrigin}
606 : dl 1.1 * is greater than or equal to {@code randomNumberBound}
607 :     */
608 :     public IntStream ints(long streamSize, int randomNumberOrigin,
609 :     int randomNumberBound) {
610 :     if (streamSize < 0L)
611 : dl 1.15 throw new IllegalArgumentException(BadSize);
612 : dl 1.1 if (randomNumberOrigin >= randomNumberBound)
613 : dl 1.15 throw new IllegalArgumentException(BadRange);
614 : dl 1.1 return StreamSupport.intStream
615 :     (new RandomIntsSpliterator
616 :     (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
617 :     false);
618 :     }
619 :    
620 :     /**
621 :     * Returns an effectively unlimited stream of pseudorandom {@code
622 :     * int} values, each conforming to the given origin and bound.
623 :     *
624 :     * @implNote This method is implemented to be equivalent to {@code
625 :     * ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
626 :     *
627 :     * @param randomNumberOrigin the origin of each random value
628 :     * @param randomNumberBound the bound of each random value
629 :     * @return a stream of pseudorandom {@code int} values,
630 : jsr166 1.10 * each with the given origin and bound
631 : dl 1.1 * @throws IllegalArgumentException if {@code randomNumberOrigin}
632 :     * is greater than or equal to {@code randomNumberBound}
633 :     */
634 :     public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
635 :     if (randomNumberOrigin >= randomNumberBound)
636 : dl 1.15 throw new IllegalArgumentException(BadRange);
637 : dl 1.1 return StreamSupport.intStream
638 :     (new RandomIntsSpliterator
639 :     (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
640 :     false);
641 :     }
642 :    
643 :     /**
644 : dl 1.7 * Returns a stream producing the given {@code streamSize} number of
645 : dl 1.1 * pseudorandom {@code long} values.
646 :     *
647 :     * @param streamSize the number of values to generate
648 : dl 1.7 * @return a stream of pseudorandom {@code long} values
649 : dl 1.1 * @throws IllegalArgumentException if {@code streamSize} is
650 : dl 1.7 * less than zero
651 : dl 1.1 */
652 :     public LongStream longs(long streamSize) {
653 :     if (streamSize < 0L)
654 : dl 1.15 throw new IllegalArgumentException(BadSize);
655 : dl 1.1 return StreamSupport.longStream
656 :     (new RandomLongsSpliterator
657 :     (this, 0L, streamSize, Long.MAX_VALUE, 0L),
658 :     false);
659 :     }
660 :    
661 :     /**
662 :     * Returns an effectively unlimited stream of pseudorandom {@code long}
663 :     * values.
664 :     *
665 :     * @implNote This method is implemented to be equivalent to {@code
666 :     * longs(Long.MAX_VALUE)}.
667 :     *
668 :     * @return a stream of pseudorandom {@code long} values
669 :     */
670 :     public LongStream longs() {
671 :     return StreamSupport.longStream
672 :     (new RandomLongsSpliterator
673 :     (this, 0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L),
674 :     false);
675 :     }
676 :    
677 :     /**
678 : dl 1.7 * Returns a stream producing the given {@code streamSize} number of
679 : dl 1.1 * pseudorandom {@code long} values, each conforming to the
680 :     * given origin and bound.
681 :     *
682 :     * @param streamSize the number of values to generate
683 :     * @param randomNumberOrigin the origin of each random value
684 :     * @param randomNumberBound the bound of each random value
685 :     * @return a stream of pseudorandom {@code long} values,
686 : jsr166 1.10 * each with the given origin and bound
687 : dl 1.1 * @throws IllegalArgumentException if {@code streamSize} is
688 : dl 1.7 * less than zero, or {@code randomNumberOrigin}
689 : dl 1.1 * is greater than or equal to {@code randomNumberBound}
690 :     */
691 :     public LongStream longs(long streamSize, long randomNumberOrigin,
692 :     long randomNumberBound) {
693 :     if (streamSize < 0L)
694 : dl 1.15 throw new IllegalArgumentException(BadSize);
695 : dl 1.1 if (randomNumberOrigin >= randomNumberBound)
696 : dl 1.15 throw new IllegalArgumentException(BadRange);
697 : dl 1.1 return StreamSupport.longStream
698 :     (new RandomLongsSpliterator
699 :     (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
700 :     false);
701 :     }
702 :    
703 :     /**
704 :     * Returns an effectively unlimited stream of pseudorandom {@code
705 :     * long} values, each conforming to the given origin and bound.
706 :     *
707 :     * @implNote This method is implemented to be equivalent to {@code
708 :     * longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
709 :     *
710 :     * @param randomNumberOrigin the origin of each random value
711 :     * @param randomNumberBound the bound of each random value
712 :     * @return a stream of pseudorandom {@code long} values,
713 : jsr166 1.10 * each with the given origin and bound
714 : dl 1.1 * @throws IllegalArgumentException if {@code randomNumberOrigin}
715 :     * is greater than or equal to {@code randomNumberBound}
716 :     */
717 :     public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
718 :     if (randomNumberOrigin >= randomNumberBound)
719 : dl 1.15 throw new IllegalArgumentException(BadRange);
720 : dl 1.1 return StreamSupport.longStream
721 :     (new RandomLongsSpliterator
722 :     (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
723 :     false);
724 :     }
725 :    
726 :     /**
727 : dl 1.7 * Returns a stream producing the given {@code streamSize} number of
728 :     * pseudorandom {@code double} values, each between zero
729 :     * (inclusive) and one (exclusive).
730 : dl 1.1 *
731 :     * @param streamSize the number of values to generate
732 :     * @return a stream of {@code double} values
733 :     * @throws IllegalArgumentException if {@code streamSize} is
734 : dl 1.7 * less than zero
735 : dl 1.1 */
736 :     public DoubleStream doubles(long streamSize) {
737 :     if (streamSize < 0L)
738 : dl 1.15 throw new IllegalArgumentException(BadSize);
739 : dl 1.1 return StreamSupport.doubleStream
740 :     (new RandomDoublesSpliterator
741 :     (this, 0L, streamSize, Double.MAX_VALUE, 0.0),
742 :     false);
743 :     }
744 :    
745 :     /**
746 :     * Returns an effectively unlimited stream of pseudorandom {@code
747 : dl 1.7 * double} values, each between zero (inclusive) and one
748 :     * (exclusive).
749 : dl 1.1 *
750 :     * @implNote This method is implemented to be equivalent to {@code
751 :     * doubles(Long.MAX_VALUE)}.
752 :     *
753 :     * @return a stream of pseudorandom {@code double} values
754 :     */
755 :     public DoubleStream doubles() {
756 :     return StreamSupport.doubleStream
757 :     (new RandomDoublesSpliterator
758 :     (this, 0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0),
759 :     false);
760 :     }
761 :    
762 :     /**
763 : dl 1.7 * Returns a stream producing the given {@code streamSize} number of
764 : dl 1.1 * pseudorandom {@code double} values, each conforming to the
765 :     * given origin and bound.
766 :     *
767 :     * @param streamSize the number of values to generate
768 :     * @param randomNumberOrigin the origin of each random value
769 :     * @param randomNumberBound the bound of each random value
770 :     * @return a stream of pseudorandom {@code double} values,
771 : jsr166 1.10 * each with the given origin and bound
772 : dl 1.1 * @throws IllegalArgumentException if {@code streamSize} is
773 : jsr166 1.10 * less than zero
774 : dl 1.1 * @throws IllegalArgumentException if {@code randomNumberOrigin}
775 :     * is greater than or equal to {@code randomNumberBound}
776 :     */
777 :     public DoubleStream doubles(long streamSize, double randomNumberOrigin,
778 :     double randomNumberBound) {
779 :     if (streamSize < 0L)
780 : dl 1.15 throw new IllegalArgumentException(BadSize);
781 : dl 1.7 if (!(randomNumberOrigin < randomNumberBound))
782 : dl 1.15 throw new IllegalArgumentException(BadRange);
783 : dl 1.1 return StreamSupport.doubleStream
784 :     (new RandomDoublesSpliterator
785 :     (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
786 :     false);
787 :     }
788 :    
789 :     /**
790 :     * Returns an effectively unlimited stream of pseudorandom {@code
791 :     * double} values, each conforming to the given origin and bound.
792 :     *
793 :     * @implNote This method is implemented to be equivalent to {@code
794 :     * doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
795 :     *
796 :     * @param randomNumberOrigin the origin of each random value
797 :     * @param randomNumberBound the bound of each random value
798 :     * @return a stream of pseudorandom {@code double} values,
799 : jsr166 1.10 * each with the given origin and bound
800 : dl 1.1 * @throws IllegalArgumentException if {@code randomNumberOrigin}
801 :     * is greater than or equal to {@code randomNumberBound}
802 :     */
803 :     public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
804 : dl 1.7 if (!(randomNumberOrigin < randomNumberBound))
805 : dl 1.15 throw new IllegalArgumentException(BadRange);
806 : dl 1.1 return StreamSupport.doubleStream
807 :     (new RandomDoublesSpliterator
808 :     (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
809 :     false);
810 :     }
811 :    
812 :     /**
813 :     * Spliterator for int streams. We multiplex the four int
814 : dl 1.7 * versions into one class by treating a bound less than origin as
815 : dl 1.1 * unbounded, and also by treating "infinite" as equivalent to
816 :     * Long.MAX_VALUE. For splits, it uses the standard divide-by-two
817 :     * approach. The long and double versions of this class are
818 :     * identical except for types.
819 :     */
820 : dl 1.11 static final class RandomIntsSpliterator implements Spliterator.OfInt {
821 : dl 1.1 final SplittableRandom rng;
822 :     long index;
823 :     final long fence;
824 :     final int origin;
825 :     final int bound;
826 :     RandomIntsSpliterator(SplittableRandom rng, long index, long fence,
827 :     int origin, int bound) {
828 :     this.rng = rng; this.index = index; this.fence = fence;
829 :     this.origin = origin; this.bound = bound;
830 :     }
831 :    
832 :     public RandomIntsSpliterator trySplit() {
833 :     long i = index, m = (i + fence) >>> 1;
834 :     return (m <= i) ? null :
835 :     new RandomIntsSpliterator(rng.split(), i, index = m, origin, bound);
836 :     }
837 :    
838 :     public long estimateSize() {
839 :     return fence - index;
840 :     }
841 :    
842 :     public int characteristics() {
843 :     return (Spliterator.SIZED | Spliterator.SUBSIZED |
844 : dl 1.4 Spliterator.NONNULL | Spliterator.IMMUTABLE);
845 : dl 1.1 }
846 :    
847 :     public boolean tryAdvance(IntConsumer consumer) {
848 :     if (consumer == null) throw new NullPointerException();
849 :     long i = index, f = fence;
850 :     if (i < f) {
851 :     consumer.accept(rng.internalNextInt(origin, bound));
852 :     index = i + 1;
853 :     return true;
854 :     }
855 :     return false;
856 :     }
857 :    
858 :     public void forEachRemaining(IntConsumer consumer) {
859 :     if (consumer == null) throw new NullPointerException();
860 :     long i = index, f = fence;
861 :     if (i < f) {
862 :     index = f;
863 : dl 1.15 SplittableRandom r = rng;
864 : dl 1.1 int o = origin, b = bound;
865 :     do {
866 : dl 1.15 consumer.accept(r.internalNextInt(o, b));
867 : dl 1.1 } while (++i < f);
868 :     }
869 :     }
870 :     }
871 :    
872 :     /**
873 :     * Spliterator for long streams.
874 :     */
875 : dl 1.11 static final class RandomLongsSpliterator implements Spliterator.OfLong {
876 : dl 1.1 final SplittableRandom rng;
877 :     long index;
878 :     final long fence;
879 :     final long origin;
880 :     final long bound;
881 :     RandomLongsSpliterator(SplittableRandom rng, long index, long fence,
882 :     long origin, long bound) {
883 :     this.rng = rng; this.index = index; this.fence = fence;
884 :     this.origin = origin; this.bound = bound;
885 :     }
886 :    
887 :     public RandomLongsSpliterator trySplit() {
888 :     long i = index, m = (i + fence) >>> 1;
889 :     return (m <= i) ? null :
890 :     new RandomLongsSpliterator(rng.split(), i, index = m, origin, bound);
891 :     }
892 :    
893 :     public long estimateSize() {
894 :     return fence - index;
895 :     }
896 :    
897 :     public int characteristics() {
898 :     return (Spliterator.SIZED | Spliterator.SUBSIZED |
899 : dl 1.4 Spliterator.NONNULL | Spliterator.IMMUTABLE);
900 : dl 1.1 }
901 :    
902 :     public boolean tryAdvance(LongConsumer consumer) {
903 :     if (consumer == null) throw new NullPointerException();
904 :     long i = index, f = fence;
905 :     if (i < f) {
906 :     consumer.accept(rng.internalNextLong(origin, bound));
907 :     index = i + 1;
908 :     return true;
909 :     }
910 :     return false;
911 :     }
912 :    
913 :     public void forEachRemaining(LongConsumer consumer) {
914 :     if (consumer == null) throw new NullPointerException();
915 :     long i = index, f = fence;
916 :     if (i < f) {
917 :     index = f;
918 : dl 1.15 SplittableRandom r = rng;
919 : dl 1.1 long o = origin, b = bound;
920 :     do {
921 : dl 1.15 consumer.accept(r.internalNextLong(o, b));
922 : dl 1.1 } while (++i < f);
923 :     }
924 :     }
925 :    
926 :     }
927 :    
928 :     /**
929 :     * Spliterator for double streams.
930 :     */
931 : dl 1.11 static final class RandomDoublesSpliterator implements Spliterator.OfDouble {
932 : dl 1.1 final SplittableRandom rng;
933 :     long index;
934 :     final long fence;
935 :     final double origin;
936 :     final double bound;
937 :     RandomDoublesSpliterator(SplittableRandom rng, long index, long fence,
938 :     double origin, double bound) {
939 :     this.rng = rng; this.index = index; this.fence = fence;
940 :     this.origin = origin; this.bound = bound;
941 :     }
942 :    
943 :     public RandomDoublesSpliterator trySplit() {
944 :     long i = index, m = (i + fence) >>> 1;
945 :     return (m <= i) ? null :
946 :     new RandomDoublesSpliterator(rng.split(), i, index = m, origin, bound);
947 :     }
948 :    
949 :     public long estimateSize() {
950 :     return fence - index;
951 :     }
952 :    
953 :     public int characteristics() {
954 :     return (Spliterator.SIZED | Spliterator.SUBSIZED |
955 : dl 1.4 Spliterator.NONNULL | Spliterator.IMMUTABLE);
956 : dl 1.1 }
957 :    
958 :     public boolean tryAdvance(DoubleConsumer consumer) {
959 :     if (consumer == null) throw new NullPointerException();
960 :     long i = index, f = fence;
961 :     if (i < f) {
962 :     consumer.accept(rng.internalNextDouble(origin, bound));
963 :     index = i + 1;
964 :     return true;
965 :     }
966 :     return false;
967 :     }
968 :    
969 :     public void forEachRemaining(DoubleConsumer consumer) {
970 :     if (consumer == null) throw new NullPointerException();
971 :     long i = index, f = fence;
972 :     if (i < f) {
973 :     index = f;
974 : dl 1.15 SplittableRandom r = rng;
975 : dl 1.1 double o = origin, b = bound;
976 :     do {
977 : dl 1.15 consumer.accept(r.internalNextDouble(o, b));
978 : dl 1.1 } while (++i < f);
979 :     }
980 :     }
981 :     }
982 :    
983 :     }

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