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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 1.18 import java.security.SecureRandom;
29 : dl 1.21 import java.net.NetworkInterface;
30 :     import java.util.Enumeration;
31 : dl 1.1 import java.util.concurrent.atomic.AtomicLong;
32 :     import java.util.function.IntConsumer;
33 :     import java.util.function.LongConsumer;
34 :     import java.util.function.DoubleConsumer;
35 :     import java.util.stream.StreamSupport;
36 :     import java.util.stream.IntStream;
37 :     import java.util.stream.LongStream;
38 :     import java.util.stream.DoubleStream;
39 :    
40 :     /**
41 :     * A generator of uniform pseudorandom values applicable for use in
42 :     * (among other contexts) isolated parallel computations that may
43 : dl 1.18 * generate subtasks. Class {@code SplittableRandom} supports methods for
44 : jsr166 1.3 * producing pseudorandom numbers of type {@code int}, {@code long},
45 : dl 1.1 * and {@code double} with similar usages as for class
46 : jsr166 1.9 * {@link java.util.Random} but differs in the following ways:
47 :     *
48 :     * <ul>
49 : dl 1.1 *
50 :     * <li>Series of generated values pass the DieHarder suite testing
51 :     * independence and uniformity properties of random number generators.
52 :     * (Most recently validated with <a
53 :     * href="http://www.phy.duke.edu/~rgb/General/dieharder.php"> version
54 :     * 3.31.1</a>.) These tests validate only the methods for certain
55 :     * types and ranges, but similar properties are expected to hold, at
56 : dl 1.11 * least approximately, for others as well. The <em>period</em>
57 :     * (length of any series of generated values before it repeats) is at
58 :     * least 2<sup>64</sup>. </li>
59 : dl 1.1 *
60 :     * <li> Method {@link #split} constructs and returns a new
61 :     * SplittableRandom instance that shares no mutable state with the
62 : dl 1.7 * current instance. However, with very high probability, the
63 :     * values collectively generated by the two objects have the same
64 : dl 1.1 * statistical properties as if the same quantity of values were
65 :     * generated by a single thread using a single {@code
66 :     * SplittableRandom} object. </li>
67 :     *
68 :     * <li>Instances of SplittableRandom are <em>not</em> thread-safe.
69 :     * They are designed to be split, not shared, across threads. For
70 :     * example, a {@link java.util.concurrent.ForkJoinTask
71 :     * fork/join-style} computation using random numbers might include a
72 :     * construction of the form {@code new
73 :     * Subtask(aSplittableRandom.split()).fork()}.
74 :     *
75 :     * <li>This class provides additional methods for generating random
76 :     * streams, that employ the above techniques when used in {@code
77 :     * stream.parallel()} mode.</li>
78 :     *
79 :     * </ul>
80 :     *
81 : dl 1.18 * <p>Instances of {@code SplittableRandom} are not cryptographically
82 :     * secure. Consider instead using {@link java.security.SecureRandom}
83 :     * in security-sensitive applications. Additionally,
84 :     * default-constructed instances do not use a cryptographically random
85 :     * seed unless the {@linkplain System#getProperty system property}
86 :     * {@code java.util.secureRandomSeed} is set to {@code true}.
87 :     *
88 : dl 1.1 * @author Guy Steele
89 : dl 1.2 * @author Doug Lea
90 : dl 1.1 * @since 1.8
91 :     */
92 :     public class SplittableRandom {
93 :    
94 :     /*
95 :     * Implementation Overview.
96 :     *
97 :     * This algorithm was inspired by the "DotMix" algorithm by
98 :     * Leiserson, Schardl, and Sukha "Deterministic Parallel
99 :     * Random-Number Generation for Dynamic-Multithreading Platforms",
100 : dl 1.15 * PPoPP 2012, as well as those in "Parallel random numbers: as
101 :     * easy as 1, 2, 3" by Salmon, Morae, Dror, and Shaw, SC 2011. It
102 :     * differs mainly in simplifying and cheapening operations.
103 :     *
104 :     * The primary update step (method nextSeed()) is to add a
105 :     * constant ("gamma") to the current (64 bit) seed, forming a
106 :     * simple sequence. The seed and the gamma values for any two
107 :     * SplittableRandom instances are highly likely to be different.
108 :     *
109 :     * Methods nextLong, nextInt, and derivatives do not return the
110 :     * sequence (seed) values, but instead a hash-like bit-mix of
111 :     * their bits, producing more independently distributed sequences.
112 : dl 1.21 * For nextLong, the mix64 function is based on David Stafford's
113 :     * (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html)
114 :     * "Mix13" variant of the "64-bit finalizer" function in Austin
115 :     * Appleby's MurmurHash3 algorithm See
116 :     * http://code.google.com/p/smhasher/wiki/MurmurHash3 . The mix32
117 :     * function is based on Stafford's Mix04 mix function, but returns
118 :     * the upper 32 bits cast as int.
119 : dl 1.15 *
120 :     * The split operation uses the current generator to form the seed
121 :     * and gamma for another SplittableRandom. To conservatively
122 :     * avoid potential correlations between seed and value generation,
123 : dl 1.21 * gamma selection (method mixGamma) uses different
124 :     * (Murmurhash3's) mix constants. To avoid potential weaknesses
125 :     * in bit-mixing transformations, we restrict gammas to odd values
126 :     * with at least 24 0-1 or 1-0 bit transitions. Rather than
127 :     * rejecting candidates with too few or too many bits set, method
128 :     * mixGamma flips some bits (which has the effect of mapping at
129 :     * most 4 to any given gamma value). This reduces the effective
130 :     * set of 64bit odd gamma values by about 2%, and serves as an
131 : dl 1.15 * automated screening for sequence constant selection that is
132 :     * left as an empirical decision in some other hashing and crypto
133 :     * algorithms.
134 :     *
135 :     * The resulting generator thus transforms a sequence in which
136 :     * (typically) many bits change on each step, with an inexpensive
137 :     * mixer with good (but less than cryptographically secure)
138 :     * avalanching.
139 :     *
140 :     * The default (no-argument) constructor, in essence, invokes
141 : dl 1.21 * split() for a common "defaultGen" SplittableRandom. Unlike
142 :     * other cases, this split must be performed in a thread-safe
143 :     * manner, so we use an AtomicLong to represent the seed rather
144 :     * than use an explicit SplittableRandom. To bootstrap the
145 :     * defaultGen, we start off using a seed based on current time and
146 :     * network interface address unless the java.util.secureRandomSeed
147 :     * property is set. This serves as a slimmed-down (and insecure)
148 :     * variant of SecureRandom that also avoids stalls that may occur
149 :     * when using /dev/random.
150 : dl 1.15 *
151 :     * It is a relatively simple matter to apply the basic design here
152 :     * to use 128 bit seeds. However, emulating 128bit arithmetic and
153 :     * carrying around twice the state add more overhead than appears
154 :     * warranted for current usages.
155 : dl 1.13 *
156 : dl 1.15 * File organization: First the non-public methods that constitute
157 :     * the main algorithm, then the main public methods, followed by
158 :     * some custom spliterator classes needed for stream methods.
159 : dl 1.1 */
160 :    
161 :     /**
162 : dl 1.21 * The golden ratio scaled to 64bits, used as the initial gamma
163 :     * value for (unsplit) SplittableRandoms.
164 : dl 1.1 */
165 : dl 1.21 private static final long GOLDEN_GAMMA = 0x9e3779b97f4a7c15L;
166 : dl 1.11
167 :     /**
168 : dl 1.5 * The least non-zero value returned by nextDouble(). This value
169 : dl 1.7 * is scaled by a random value of 53 bits to produce a result.
170 : dl 1.5 */
171 : dl 1.21 private static final double DOUBLE_ULP = 1.0 / (1L << 53);
172 : dl 1.5
173 :     /**
174 : dl 1.15 * The seed. Updated only via method nextSeed.
175 : dl 1.1 */
176 :     private long seed;
177 :    
178 :     /**
179 : dl 1.15 * The step value.
180 : dl 1.1 */
181 :     private final long gamma;
182 :    
183 :     /**
184 : dl 1.15 * Internal constructor used by all others except default constructor.
185 : dl 1.1 */
186 : dl 1.15 private SplittableRandom(long seed, long gamma) {
187 :     this.seed = seed;
188 :     this.gamma = gamma;
189 : dl 1.1 }
190 :    
191 :     /**
192 : dl 1.21 * Computes Stafford variant 13 of 64bit mix function.
193 : dl 1.1 */
194 :     private static long mix64(long z) {
195 : dl 1.21 z *= 0xbf58476d1ce4e5b9L;
196 :     z = (z ^ (z >>> 32)) * 0x94d049bb133111ebL;
197 :     return z ^ (z >>> 32);
198 :     }
199 :    
200 :     private static long xmix64(long z) {
201 :     z *= 0xbf58476d1ce4e5b9L;
202 :     z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
203 :     return z ^ (z >>> 31);
204 : dl 1.1 }
205 :    
206 :     /**
207 : dl 1.21 * Returns the 32 high bits of Stafford variant 4 mix64 function as int.
208 : dl 1.1 */
209 :     private static int mix32(long z) {
210 : dl 1.21 z *= 0x62a9d9ed799705f5L;
211 :     return (int)(((z ^ (z >>> 28)) * 0xcb24d0a5c88c35b3L) >>> 32);
212 : dl 1.1 }
213 :    
214 :     /**
215 : dl 1.15 * Returns the gamma value to use for a new split instance.
216 : dl 1.13 */
217 : dl 1.21 private static long mixGamma(long z) {
218 :     z *= 0xff51afd7ed558ccdL; // MurmurHash3 mix constants
219 :     z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
220 :     z = (z ^ (z >>> 33)) | 1L; // force to be odd
221 :     int n = Long.bitCount(z ^ (z >>> 1)); // ensure enough transitions
222 :     return (n < 24) ? z ^ 0xaaaaaaaaaaaaaaaaL : z;
223 : dl 1.13 }
224 :    
225 :     /**
226 : dl 1.15 * Adds gamma to seed.
227 : dl 1.7 */
228 : dl 1.15 private long nextSeed() {
229 :     return seed += gamma;
230 : dl 1.7 }
231 :    
232 :     /**
233 : dl 1.15 * The seed generator for default constructors.
234 : dl 1.7 */
235 : dl 1.21 private static final AtomicLong defaultGen = new AtomicLong(initialSeed());
236 : dl 1.7
237 : dl 1.18 private static long initialSeed() {
238 : dl 1.21 String pp = java.security.AccessController.doPrivileged(
239 :     new sun.security.action.GetPropertyAction(
240 :     "java.util.secureRandomSeed"));
241 :     if (pp != null && pp.equalsIgnoreCase("true")) {
242 :     byte[] seedBytes = java.security.SecureRandom.getSeed(8);
243 :     long s = (long)(seedBytes[0]) & 0xffL;
244 :     for (int i = 1; i < 8; ++i)
245 :     s = (s << 8) | ((long)(seedBytes[i]) & 0xffL);
246 :     return s;
247 : dl 1.18 }
248 : dl 1.21 long h = 0L;
249 : jsr166 1.17 try {
250 : dl 1.21 Enumeration<NetworkInterface> ifcs =
251 :     NetworkInterface.getNetworkInterfaces();
252 :     boolean retry = false; // retry once if getHardwareAddress is null
253 :     while (ifcs.hasMoreElements()) {
254 :     NetworkInterface ifc = ifcs.nextElement();
255 :     if (!ifc.isVirtual()) { // skip fake addresses
256 :     byte[] bs = ifc.getHardwareAddress();
257 :     if (bs != null) {
258 :     int n = bs.length;
259 :     int m = Math.min(n >>> 1, 4);
260 :     for (int i = 0; i < m; ++i)
261 :     h = (h << 16) ^ (bs[i] << 8) ^ bs[n-1-i];
262 :     if (m < 4)
263 :     h = (h << 8) ^ bs[n-1-m];
264 :     h = mix64(h);
265 :     break;
266 :     }
267 :     else if (!retry)
268 :     retry = true;
269 :     else
270 :     break;
271 :     }
272 :     }
273 : dl 1.18 } catch (Exception ignore) {
274 : jsr166 1.17 }
275 : dl 1.21 return (h ^ mix64(System.currentTimeMillis()) ^
276 : dl 1.18 mix64(System.nanoTime()));
277 : dl 1.1 }
278 :    
279 : dl 1.15 // IllegalArgumentException messages
280 :     static final String BadBound = "bound must be positive";
281 :     static final String BadRange = "bound must be greater than origin";
282 :     static final String BadSize = "size must be non-negative";
283 : dl 1.12
284 : dl 1.1 /*
285 :     * Internal versions of nextX methods used by streams, as well as
286 :     * the public nextX(origin, bound) methods. These exist mainly to
287 :     * avoid the need for multiple versions of stream spliterators
288 :     * across the different exported forms of streams.
289 :     */
290 :    
291 :     /**
292 :     * The form of nextLong used by LongStream Spliterators. If
293 :     * origin is greater than bound, acts as unbounded form of
294 :     * nextLong, else as bounded form.
295 :     *
296 :     * @param origin the least value, unless greater than bound
297 :     * @param bound the upper bound (exclusive), must not equal origin
298 :     * @return a pseudorandom value
299 :     */
300 :     final long internalNextLong(long origin, long bound) {
301 :     /*
302 :     * Four Cases:
303 :     *
304 :     * 1. If the arguments indicate unbounded form, act as
305 :     * nextLong().
306 :     *
307 :     * 2. If the range is an exact power of two, apply the
308 :     * associated bit mask.
309 :     *
310 :     * 3. If the range is positive, loop to avoid potential bias
311 :     * when the implicit nextLong() bound (2<sup>64</sup>) is not
312 :     * evenly divisible by the range. The loop rejects candidates
313 :     * computed from otherwise over-represented values. The
314 :     * expected number of iterations under an ideal generator
315 : dl 1.4 * varies from 1 to 2, depending on the bound. The loop itself
316 :     * takes an unlovable form. Because the first candidate is
317 :     * already available, we need a break-in-the-middle
318 :     * construction, which is concisely but cryptically performed
319 :     * within the while-condition of a body-less for loop.
320 : dl 1.1 *
321 :     * 4. Otherwise, the range cannot be represented as a positive
322 : dl 1.4 * long. The loop repeatedly generates unbounded longs until
323 :     * obtaining a candidate meeting constraints (with an expected
324 :     * number of iterations of less than two).
325 : dl 1.1 */
326 :    
327 :     long r = mix64(nextSeed());
328 :     if (origin < bound) {
329 :     long n = bound - origin, m = n - 1;
330 : dl 1.7 if ((n & m) == 0L) // power of two
331 : dl 1.1 r = (r & m) + origin;
332 : dl 1.7 else if (n > 0L) { // reject over-represented candidates
333 : dl 1.1 for (long u = r >>> 1; // ensure nonnegative
334 : dl 1.7 u + m - (r = u % n) < 0L; // rejection check
335 : dl 1.1 u = mix64(nextSeed()) >>> 1) // retry
336 :     ;
337 :     r += origin;
338 :     }
339 : dl 1.7 else { // range not representable as long
340 : dl 1.1 while (r < origin || r >= bound)
341 :     r = mix64(nextSeed());
342 :     }
343 :     }
344 :     return r;
345 :     }
346 :    
347 :     /**
348 :     * The form of nextInt used by IntStream Spliterators.
349 :     * Exactly the same as long version, except for types.
350 :     *
351 :     * @param origin the least value, unless greater than bound
352 :     * @param bound the upper bound (exclusive), must not equal origin
353 :     * @return a pseudorandom value
354 :     */
355 :     final int internalNextInt(int origin, int bound) {
356 :     int r = mix32(nextSeed());
357 :     if (origin < bound) {
358 :     int n = bound - origin, m = n - 1;
359 : dl 1.13 if ((n & m) == 0)
360 : dl 1.1 r = (r & m) + origin;
361 :     else if (n > 0) {
362 :     for (int u = r >>> 1;
363 : dl 1.7 u + m - (r = u % n) < 0;
364 : dl 1.1 u = mix32(nextSeed()) >>> 1)
365 :     ;
366 :     r += origin;
367 :     }
368 :     else {
369 :     while (r < origin || r >= bound)
370 :     r = mix32(nextSeed());
371 :     }
372 :     }
373 :     return r;
374 :     }
375 :    
376 :     /**
377 :     * The form of nextDouble used by DoubleStream Spliterators.
378 :     *
379 :     * @param origin the least value, unless greater than bound
380 :     * @param bound the upper bound (exclusive), must not equal origin
381 :     * @return a pseudorandom value
382 :     */
383 :     final double internalNextDouble(double origin, double bound) {
384 : dl 1.21 double r = (nextLong() >>> 11) * DOUBLE_ULP;
385 : dl 1.1 if (origin < bound) {
386 :     r = r * (bound - origin) + origin;
387 : dl 1.7 if (r >= bound) // correct for rounding
388 : dl 1.1 r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
389 :     }
390 :     return r;
391 :     }
392 :    
393 :     /* ---------------- public methods ---------------- */
394 :    
395 :     /**
396 : dl 1.7 * Creates a new SplittableRandom instance using the specified
397 :     * initial seed. SplittableRandom instances created with the same
398 : dl 1.11 * seed in the same program generate identical sequences of values.
399 : dl 1.1 *
400 :     * @param seed the initial seed
401 :     */
402 :     public SplittableRandom(long seed) {
403 : dl 1.21 this(seed, GOLDEN_GAMMA);
404 : dl 1.1 }
405 :    
406 :     /**
407 :     * Creates a new SplittableRandom instance that is likely to
408 :     * generate sequences of values that are statistically independent
409 :     * of those of any other instances in the current program; and
410 :     * may, and typically does, vary across program invocations.
411 :     */
412 : dl 1.21 public SplittableRandom() { // emulate defaultGen.split()
413 :     long s = defaultGen.getAndAdd(2*GOLDEN_GAMMA);
414 :     this.seed = mix64(s);
415 :     this.gamma = mixGamma(s + GOLDEN_GAMMA);
416 : dl 1.1 }
417 :    
418 :     /**
419 :     * Constructs and returns a new SplittableRandom instance that
420 :     * shares no mutable state with this instance. However, with very
421 :     * high probability, the set of values collectively generated by
422 :     * the two objects has the same statistical properties as if the
423 :     * same quantity of values were generated by a single thread using
424 :     * a single SplittableRandom object. Either or both of the two
425 :     * objects may be further split using the {@code split()} method,
426 :     * and the same expected statistical properties apply to the
427 :     * entire set of generators constructed by such recursive
428 :     * splitting.
429 :     *
430 :     * @return the new SplittableRandom instance
431 :     */
432 :     public SplittableRandom split() {
433 : dl 1.21 return new SplittableRandom(nextLong(), mixGamma(nextSeed()));
434 : dl 1.1 }
435 :    
436 :     /**
437 :     * Returns a pseudorandom {@code int} value.
438 :     *
439 : dl 1.7 * @return a pseudorandom {@code int} value
440 : dl 1.1 */
441 :     public int nextInt() {
442 :     return mix32(nextSeed());
443 :     }
444 :    
445 :     /**
446 : dl 1.7 * Returns a pseudorandom {@code int} value between zero (inclusive)
447 : dl 1.1 * and the specified bound (exclusive).
448 :     *
449 : dl 1.18 * @param bound the upper bound (exclusive). Must be positive.
450 : dl 1.7 * @return a pseudorandom {@code int} value between zero
451 : jsr166 1.10 * (inclusive) and the bound (exclusive)
452 : dl 1.16 * @throws IllegalArgumentException if {@code bound} is not positive
453 : dl 1.1 */
454 :     public int nextInt(int bound) {
455 :     if (bound <= 0)
456 : dl 1.15 throw new IllegalArgumentException(BadBound);
457 : dl 1.1 // Specialize internalNextInt for origin 0
458 :     int r = mix32(nextSeed());
459 :     int m = bound - 1;
460 : dl 1.13 if ((bound & m) == 0) // power of two
461 : dl 1.1 r &= m;
462 :     else { // reject over-represented candidates
463 :     for (int u = r >>> 1;
464 : dl 1.7 u + m - (r = u % bound) < 0;
465 : dl 1.1 u = mix32(nextSeed()) >>> 1)
466 :     ;
467 :     }
468 :     return r;
469 :     }
470 :    
471 :     /**
472 :     * Returns a pseudorandom {@code int} value between the specified
473 :     * origin (inclusive) and the specified bound (exclusive).
474 :     *
475 :     * @param origin the least value returned
476 :     * @param bound the upper bound (exclusive)
477 :     * @return a pseudorandom {@code int} value between the origin
478 : jsr166 1.10 * (inclusive) and the bound (exclusive)
479 : dl 1.7 * @throws IllegalArgumentException if {@code origin} is greater than
480 : dl 1.1 * or equal to {@code bound}
481 :     */
482 :     public int nextInt(int origin, int bound) {
483 :     if (origin >= bound)
484 : dl 1.15 throw new IllegalArgumentException(BadRange);
485 : dl 1.1 return internalNextInt(origin, bound);
486 :     }
487 :    
488 :     /**
489 :     * Returns a pseudorandom {@code long} value.
490 :     *
491 : dl 1.7 * @return a pseudorandom {@code long} value
492 : dl 1.1 */
493 :     public long nextLong() {
494 :     return mix64(nextSeed());
495 :     }
496 :    
497 :     /**
498 : dl 1.7 * Returns a pseudorandom {@code long} value between zero (inclusive)
499 : dl 1.1 * and the specified bound (exclusive).
500 :     *
501 : dl 1.18 * @param bound the upper bound (exclusive). Must be positive.
502 : dl 1.7 * @return a pseudorandom {@code long} value between zero
503 : jsr166 1.10 * (inclusive) and the bound (exclusive)
504 : dl 1.16 * @throws IllegalArgumentException if {@code bound} is not positive
505 : dl 1.1 */
506 :     public long nextLong(long bound) {
507 :     if (bound <= 0)
508 : dl 1.15 throw new IllegalArgumentException(BadBound);
509 : dl 1.1 // Specialize internalNextLong for origin 0
510 :     long r = mix64(nextSeed());
511 :     long m = bound - 1;
512 :     if ((bound & m) == 0L) // power of two
513 :     r &= m;
514 :     else { // reject over-represented candidates
515 :     for (long u = r >>> 1;
516 :     u + m - (r = u % bound) < 0L;
517 :     u = mix64(nextSeed()) >>> 1)
518 :     ;
519 :     }
520 :     return r;
521 :     }
522 :    
523 :     /**
524 :     * Returns a pseudorandom {@code long} value between the specified
525 :     * origin (inclusive) and the specified bound (exclusive).
526 :     *
527 :     * @param origin the least value returned
528 :     * @param bound the upper bound (exclusive)
529 :     * @return a pseudorandom {@code long} value between the origin
530 : jsr166 1.10 * (inclusive) and the bound (exclusive)
531 : dl 1.7 * @throws IllegalArgumentException if {@code origin} is greater than
532 : dl 1.1 * or equal to {@code bound}
533 :     */
534 :     public long nextLong(long origin, long bound) {
535 :     if (origin >= bound)
536 : dl 1.15 throw new IllegalArgumentException(BadRange);
537 : dl 1.1 return internalNextLong(origin, bound);
538 :     }
539 :    
540 :     /**
541 : dl 1.7 * Returns a pseudorandom {@code double} value between zero
542 :     * (inclusive) and one (exclusive).
543 : dl 1.1 *
544 : dl 1.7 * @return a pseudorandom {@code double} value between zero
545 : dl 1.18 * (inclusive) and one (exclusive)
546 : dl 1.1 */
547 :     public double nextDouble() {
548 : dl 1.21 return (mix64(nextSeed()) >>> 11) * DOUBLE_ULP;
549 : dl 1.1 }
550 :    
551 :     /**
552 :     * Returns a pseudorandom {@code double} value between 0.0
553 :     * (inclusive) and the specified bound (exclusive).
554 :     *
555 : dl 1.18 * @param bound the upper bound (exclusive). Must be positive.
556 : dl 1.7 * @return a pseudorandom {@code double} value between zero
557 : jsr166 1.10 * (inclusive) and the bound (exclusive)
558 : dl 1.16 * @throws IllegalArgumentException if {@code bound} is not positive
559 : dl 1.1 */
560 :     public double nextDouble(double bound) {
561 : dl 1.7 if (!(bound > 0.0))
562 : dl 1.15 throw new IllegalArgumentException(BadBound);
563 : dl 1.21 double result = (mix64(nextSeed()) >>> 11) * DOUBLE_ULP * bound;
564 : dl 1.1 return (result < bound) ? result : // correct for rounding
565 :     Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
566 :     }
567 :    
568 :     /**
569 : dl 1.7 * Returns a pseudorandom {@code double} value between the specified
570 : dl 1.1 * origin (inclusive) and bound (exclusive).
571 :     *
572 :     * @param origin the least value returned
573 : dl 1.18 * @param bound the upper bound (exclusive)
574 : dl 1.1 * @return a pseudorandom {@code double} value between the origin
575 : jsr166 1.10 * (inclusive) and the bound (exclusive)
576 : dl 1.1 * @throws IllegalArgumentException if {@code origin} is greater than
577 :     * or equal to {@code bound}
578 :     */
579 :     public double nextDouble(double origin, double bound) {
580 : dl 1.7 if (!(origin < bound))
581 : dl 1.15 throw new IllegalArgumentException(BadRange);
582 : dl 1.1 return internalNextDouble(origin, bound);
583 :     }
584 :    
585 : dl 1.11 /**
586 :     * Returns a pseudorandom {@code boolean} value.
587 :     *
588 :     * @return a pseudorandom {@code boolean} value
589 :     */
590 :     public boolean nextBoolean() {
591 :     return mix32(nextSeed()) < 0;
592 :     }
593 :    
594 : dl 1.1 // stream methods, coded in a way intended to better isolate for
595 :     // maintenance purposes the small differences across forms.
596 :    
597 :     /**
598 : dl 1.16 * Returns a stream producing the given {@code streamSize} number
599 :     * of pseudorandom {@code int} values from this generator and/or
600 :     * one split from it.
601 : dl 1.1 *
602 :     * @param streamSize the number of values to generate
603 :     * @return a stream of pseudorandom {@code int} values
604 :     * @throws IllegalArgumentException if {@code streamSize} is
605 : dl 1.7 * less than zero
606 : dl 1.1 */
607 :     public IntStream ints(long streamSize) {
608 :     if (streamSize < 0L)
609 : dl 1.15 throw new IllegalArgumentException(BadSize);
610 : dl 1.1 return StreamSupport.intStream
611 :     (new RandomIntsSpliterator
612 :     (this, 0L, streamSize, Integer.MAX_VALUE, 0),
613 :     false);
614 :     }
615 :    
616 :     /**
617 :     * Returns an effectively unlimited stream of pseudorandom {@code int}
618 : dl 1.16 * values from this generator and/or one split from it.
619 : dl 1.1 *
620 :     * @implNote This method is implemented to be equivalent to {@code
621 :     * ints(Long.MAX_VALUE)}.
622 :     *
623 :     * @return a stream of pseudorandom {@code int} values
624 :     */
625 :     public IntStream ints() {
626 :     return StreamSupport.intStream
627 :     (new RandomIntsSpliterator
628 :     (this, 0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0),
629 :     false);
630 :     }
631 :    
632 :     /**
633 : dl 1.16 * Returns a stream producing the given {@code streamSize} number
634 : dl 1.18 * of pseudorandom {@code int} values from this generator and/or one split
635 :     * from it; each value conforms to the given origin (inclusive) and bound
636 :     * (exclusive).
637 : dl 1.1 *
638 :     * @param streamSize the number of values to generate
639 : dl 1.18 * @param randomNumberOrigin the origin (inclusive) of each random value
640 :     * @param randomNumberBound the bound (exclusive) of each random value
641 : dl 1.1 * @return a stream of pseudorandom {@code int} values,
642 : dl 1.18 * each with the given origin (inclusive) and bound (exclusive)
643 : dl 1.1 * @throws IllegalArgumentException if {@code streamSize} is
644 : dl 1.7 * less than zero, or {@code randomNumberOrigin}
645 : dl 1.1 * is greater than or equal to {@code randomNumberBound}
646 :     */
647 :     public IntStream ints(long streamSize, int randomNumberOrigin,
648 :     int randomNumberBound) {
649 :     if (streamSize < 0L)
650 : dl 1.15 throw new IllegalArgumentException(BadSize);
651 : dl 1.1 if (randomNumberOrigin >= randomNumberBound)
652 : dl 1.15 throw new IllegalArgumentException(BadRange);
653 : dl 1.1 return StreamSupport.intStream
654 :     (new RandomIntsSpliterator
655 :     (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
656 :     false);
657 :     }
658 :    
659 :     /**
660 :     * Returns an effectively unlimited stream of pseudorandom {@code
661 : dl 1.18 * int} values from this generator and/or one split from it; each value
662 :     * conforms to the given origin (inclusive) and bound (exclusive).
663 : dl 1.1 *
664 :     * @implNote This method is implemented to be equivalent to {@code
665 :     * ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
666 :     *
667 : dl 1.18 * @param randomNumberOrigin the origin (inclusive) of each random value
668 :     * @param randomNumberBound the bound (exclusive) of each random value
669 : dl 1.1 * @return a stream of pseudorandom {@code int} values,
670 : dl 1.18 * each with the given origin (inclusive) and bound (exclusive)
671 : dl 1.1 * @throws IllegalArgumentException if {@code randomNumberOrigin}
672 :     * is greater than or equal to {@code randomNumberBound}
673 :     */
674 :     public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
675 :     if (randomNumberOrigin >= randomNumberBound)
676 : dl 1.15 throw new IllegalArgumentException(BadRange);
677 : dl 1.1 return StreamSupport.intStream
678 :     (new RandomIntsSpliterator
679 :     (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
680 :     false);
681 :     }
682 :    
683 :     /**
684 : dl 1.16 * Returns a stream producing the given {@code streamSize} number
685 :     * of pseudorandom {@code long} values from this generator and/or
686 :     * one split from it.
687 : dl 1.1 *
688 :     * @param streamSize the number of values to generate
689 : dl 1.7 * @return a stream of pseudorandom {@code long} values
690 : dl 1.1 * @throws IllegalArgumentException if {@code streamSize} is
691 : dl 1.7 * less than zero
692 : dl 1.1 */
693 :     public LongStream longs(long streamSize) {
694 :     if (streamSize < 0L)
695 : dl 1.15 throw new IllegalArgumentException(BadSize);
696 : dl 1.1 return StreamSupport.longStream
697 :     (new RandomLongsSpliterator
698 :     (this, 0L, streamSize, Long.MAX_VALUE, 0L),
699 :     false);
700 :     }
701 :    
702 :     /**
703 : dl 1.16 * Returns an effectively unlimited stream of pseudorandom {@code
704 :     * long} values from this generator and/or one split from it.
705 : dl 1.1 *
706 :     * @implNote This method is implemented to be equivalent to {@code
707 :     * longs(Long.MAX_VALUE)}.
708 :     *
709 :     * @return a stream of pseudorandom {@code long} values
710 :     */
711 :     public LongStream longs() {
712 :     return StreamSupport.longStream
713 :     (new RandomLongsSpliterator
714 :     (this, 0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L),
715 :     false);
716 :     }
717 :    
718 :     /**
719 : dl 1.7 * Returns a stream producing the given {@code streamSize} number of
720 : dl 1.18 * pseudorandom {@code long} values from this generator and/or one split
721 :     * from it; each value conforms to the given origin (inclusive) and bound
722 :     * (exclusive).
723 : dl 1.1 *
724 :     * @param streamSize the number of values to generate
725 : dl 1.18 * @param randomNumberOrigin the origin (inclusive) of each random value
726 :     * @param randomNumberBound the bound (exclusive) of each random value
727 : dl 1.1 * @return a stream of pseudorandom {@code long} values,
728 : dl 1.18 * each with the given origin (inclusive) and bound (exclusive)
729 : dl 1.1 * @throws IllegalArgumentException if {@code streamSize} is
730 : dl 1.7 * less than zero, or {@code randomNumberOrigin}
731 : dl 1.1 * is greater than or equal to {@code randomNumberBound}
732 :     */
733 :     public LongStream longs(long streamSize, long randomNumberOrigin,
734 :     long randomNumberBound) {
735 :     if (streamSize < 0L)
736 : dl 1.15 throw new IllegalArgumentException(BadSize);
737 : dl 1.1 if (randomNumberOrigin >= randomNumberBound)
738 : dl 1.15 throw new IllegalArgumentException(BadRange);
739 : dl 1.1 return StreamSupport.longStream
740 :     (new RandomLongsSpliterator
741 :     (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
742 :     false);
743 :     }
744 :    
745 :     /**
746 :     * Returns an effectively unlimited stream of pseudorandom {@code
747 : dl 1.18 * long} values from this generator and/or one split from it; each value
748 :     * conforms to the given origin (inclusive) and bound (exclusive).
749 : dl 1.1 *
750 :     * @implNote This method is implemented to be equivalent to {@code
751 :     * longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
752 :     *
753 : dl 1.18 * @param randomNumberOrigin the origin (inclusive) of each random value
754 :     * @param randomNumberBound the bound (exclusive) of each random value
755 : dl 1.1 * @return a stream of pseudorandom {@code long} values,
756 : dl 1.18 * each with the given origin (inclusive) and bound (exclusive)
757 : dl 1.1 * @throws IllegalArgumentException if {@code randomNumberOrigin}
758 :     * is greater than or equal to {@code randomNumberBound}
759 :     */
760 :     public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
761 :     if (randomNumberOrigin >= randomNumberBound)
762 : dl 1.15 throw new IllegalArgumentException(BadRange);
763 : dl 1.1 return StreamSupport.longStream
764 :     (new RandomLongsSpliterator
765 :     (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
766 :     false);
767 :     }
768 :    
769 :     /**
770 : dl 1.7 * Returns a stream producing the given {@code streamSize} number of
771 : dl 1.18 * pseudorandom {@code double} values from this generator and/or one split
772 :     * from it; each value is between zero (inclusive) and one (exclusive).
773 : dl 1.1 *
774 :     * @param streamSize the number of values to generate
775 :     * @return a stream of {@code double} values
776 :     * @throws IllegalArgumentException if {@code streamSize} is
777 : dl 1.7 * less than zero
778 : dl 1.1 */
779 :     public DoubleStream doubles(long streamSize) {
780 :     if (streamSize < 0L)
781 : dl 1.15 throw new IllegalArgumentException(BadSize);
782 : dl 1.1 return StreamSupport.doubleStream
783 :     (new RandomDoublesSpliterator
784 :     (this, 0L, streamSize, Double.MAX_VALUE, 0.0),
785 :     false);
786 :     }
787 :    
788 :     /**
789 :     * Returns an effectively unlimited stream of pseudorandom {@code
790 : dl 1.18 * double} values from this generator and/or one split from it; each value
791 :     * is between zero (inclusive) and one (exclusive).
792 : dl 1.1 *
793 :     * @implNote This method is implemented to be equivalent to {@code
794 :     * doubles(Long.MAX_VALUE)}.
795 :     *
796 :     * @return a stream of pseudorandom {@code double} values
797 :     */
798 :     public DoubleStream doubles() {
799 :     return StreamSupport.doubleStream
800 :     (new RandomDoublesSpliterator
801 :     (this, 0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0),
802 :     false);
803 :     }
804 :    
805 :     /**
806 : dl 1.7 * Returns a stream producing the given {@code streamSize} number of
807 : dl 1.18 * pseudorandom {@code double} values from this generator and/or one split
808 :     * from it; each value conforms to the given origin (inclusive) and bound
809 :     * (exclusive).
810 : dl 1.1 *
811 :     * @param streamSize the number of values to generate
812 : dl 1.18 * @param randomNumberOrigin the origin (inclusive) of each random value
813 :     * @param randomNumberBound the bound (exclusive) of each random value
814 : dl 1.1 * @return a stream of pseudorandom {@code double} values,
815 : dl 1.18 * each with the given origin (inclusive) and bound (exclusive)
816 : dl 1.1 * @throws IllegalArgumentException if {@code streamSize} is
817 : dl 1.18 * less than zero
818 : dl 1.1 * @throws IllegalArgumentException if {@code randomNumberOrigin}
819 :     * is greater than or equal to {@code randomNumberBound}
820 :     */
821 :     public DoubleStream doubles(long streamSize, double randomNumberOrigin,
822 :     double randomNumberBound) {
823 :     if (streamSize < 0L)
824 : dl 1.15 throw new IllegalArgumentException(BadSize);
825 : dl 1.7 if (!(randomNumberOrigin < randomNumberBound))
826 : dl 1.15 throw new IllegalArgumentException(BadRange);
827 : dl 1.1 return StreamSupport.doubleStream
828 :     (new RandomDoublesSpliterator
829 :     (this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
830 :     false);
831 :     }
832 :    
833 :     /**
834 :     * Returns an effectively unlimited stream of pseudorandom {@code
835 : dl 1.18 * double} values from this generator and/or one split from it; each value
836 :     * conforms to the given origin (inclusive) and bound (exclusive).
837 : dl 1.1 *
838 :     * @implNote This method is implemented to be equivalent to {@code
839 :     * doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
840 :     *
841 : dl 1.18 * @param randomNumberOrigin the origin (inclusive) of each random value
842 :     * @param randomNumberBound the bound (exclusive) of each random value
843 : dl 1.1 * @return a stream of pseudorandom {@code double} values,
844 : dl 1.18 * each with the given origin (inclusive) and bound (exclusive)
845 : dl 1.1 * @throws IllegalArgumentException if {@code randomNumberOrigin}
846 :     * is greater than or equal to {@code randomNumberBound}
847 :     */
848 :     public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
849 : dl 1.7 if (!(randomNumberOrigin < randomNumberBound))
850 : dl 1.15 throw new IllegalArgumentException(BadRange);
851 : dl 1.1 return StreamSupport.doubleStream
852 :     (new RandomDoublesSpliterator
853 :     (this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
854 :     false);
855 :     }
856 :    
857 :     /**
858 :     * Spliterator for int streams. We multiplex the four int
859 : dl 1.7 * versions into one class by treating a bound less than origin as
860 : dl 1.1 * unbounded, and also by treating "infinite" as equivalent to
861 :     * Long.MAX_VALUE. For splits, it uses the standard divide-by-two
862 :     * approach. The long and double versions of this class are
863 :     * identical except for types.
864 :     */
865 : dl 1.11 static final class RandomIntsSpliterator implements Spliterator.OfInt {
866 : dl 1.1 final SplittableRandom rng;
867 :     long index;
868 :     final long fence;
869 :     final int origin;
870 :     final int bound;
871 :     RandomIntsSpliterator(SplittableRandom rng, long index, long fence,
872 :     int origin, int bound) {
873 :     this.rng = rng; this.index = index; this.fence = fence;
874 :     this.origin = origin; this.bound = bound;
875 :     }
876 :    
877 :     public RandomIntsSpliterator trySplit() {
878 :     long i = index, m = (i + fence) >>> 1;
879 :     return (m <= i) ? null :
880 :     new RandomIntsSpliterator(rng.split(), i, index = m, origin, bound);
881 :     }
882 :    
883 :     public long estimateSize() {
884 :     return fence - index;
885 :     }
886 :    
887 :     public int characteristics() {
888 :     return (Spliterator.SIZED | Spliterator.SUBSIZED |
889 : dl 1.4 Spliterator.NONNULL | Spliterator.IMMUTABLE);
890 : dl 1.1 }
891 :    
892 :     public boolean tryAdvance(IntConsumer consumer) {
893 :     if (consumer == null) throw new NullPointerException();
894 :     long i = index, f = fence;
895 :     if (i < f) {
896 :     consumer.accept(rng.internalNextInt(origin, bound));
897 :     index = i + 1;
898 :     return true;
899 :     }
900 :     return false;
901 :     }
902 :    
903 :     public void forEachRemaining(IntConsumer consumer) {
904 :     if (consumer == null) throw new NullPointerException();
905 :     long i = index, f = fence;
906 :     if (i < f) {
907 :     index = f;
908 : dl 1.15 SplittableRandom r = rng;
909 : dl 1.1 int o = origin, b = bound;
910 :     do {
911 : dl 1.15 consumer.accept(r.internalNextInt(o, b));
912 : dl 1.1 } while (++i < f);
913 :     }
914 :     }
915 :     }
916 :    
917 :     /**
918 :     * Spliterator for long streams.
919 :     */
920 : dl 1.11 static final class RandomLongsSpliterator implements Spliterator.OfLong {
921 : dl 1.1 final SplittableRandom rng;
922 :     long index;
923 :     final long fence;
924 :     final long origin;
925 :     final long bound;
926 :     RandomLongsSpliterator(SplittableRandom rng, long index, long fence,
927 :     long origin, long bound) {
928 :     this.rng = rng; this.index = index; this.fence = fence;
929 :     this.origin = origin; this.bound = bound;
930 :     }
931 :    
932 :     public RandomLongsSpliterator trySplit() {
933 :     long i = index, m = (i + fence) >>> 1;
934 :     return (m <= i) ? null :
935 :     new RandomLongsSpliterator(rng.split(), i, index = m, origin, bound);
936 :     }
937 :    
938 :     public long estimateSize() {
939 :     return fence - index;
940 :     }
941 :    
942 :     public int characteristics() {
943 :     return (Spliterator.SIZED | Spliterator.SUBSIZED |
944 : dl 1.4 Spliterator.NONNULL | Spliterator.IMMUTABLE);
945 : dl 1.1 }
946 :    
947 :     public boolean tryAdvance(LongConsumer consumer) {
948 :     if (consumer == null) throw new NullPointerException();
949 :     long i = index, f = fence;
950 :     if (i < f) {
951 :     consumer.accept(rng.internalNextLong(origin, bound));
952 :     index = i + 1;
953 :     return true;
954 :     }
955 :     return false;
956 :     }
957 :    
958 :     public void forEachRemaining(LongConsumer consumer) {
959 :     if (consumer == null) throw new NullPointerException();
960 :     long i = index, f = fence;
961 :     if (i < f) {
962 :     index = f;
963 : dl 1.15 SplittableRandom r = rng;
964 : dl 1.1 long o = origin, b = bound;
965 :     do {
966 : dl 1.15 consumer.accept(r.internalNextLong(o, b));
967 : dl 1.1 } while (++i < f);
968 :     }
969 :     }
970 :    
971 :     }
972 :    
973 :     /**
974 :     * Spliterator for double streams.
975 :     */
976 : dl 1.11 static final class RandomDoublesSpliterator implements Spliterator.OfDouble {
977 : dl 1.1 final SplittableRandom rng;
978 :     long index;
979 :     final long fence;
980 :     final double origin;
981 :     final double bound;
982 :     RandomDoublesSpliterator(SplittableRandom rng, long index, long fence,
983 :     double origin, double bound) {
984 :     this.rng = rng; this.index = index; this.fence = fence;
985 :     this.origin = origin; this.bound = bound;
986 :     }
987 :    
988 :     public RandomDoublesSpliterator trySplit() {
989 :     long i = index, m = (i + fence) >>> 1;
990 :     return (m <= i) ? null :
991 :     new RandomDoublesSpliterator(rng.split(), i, index = m, origin, bound);
992 :     }
993 :    
994 :     public long estimateSize() {
995 :     return fence - index;
996 :     }
997 :    
998 :     public int characteristics() {
999 :     return (Spliterator.SIZED | Spliterator.SUBSIZED |
1000 : dl 1.4 Spliterator.NONNULL | Spliterator.IMMUTABLE);
1001 : dl 1.1 }
1002 :    
1003 :     public boolean tryAdvance(DoubleConsumer consumer) {
1004 :     if (consumer == null) throw new NullPointerException();
1005 :     long i = index, f = fence;
1006 :     if (i < f) {
1007 :     consumer.accept(rng.internalNextDouble(origin, bound));
1008 :     index = i + 1;
1009 :     return true;
1010 :     }
1011 :     return false;
1012 :     }
1013 :    
1014 :     public void forEachRemaining(DoubleConsumer consumer) {
1015 :     if (consumer == null) throw new NullPointerException();
1016 :     long i = index, f = fence;
1017 :     if (i < f) {
1018 :     index = f;
1019 : dl 1.15 SplittableRandom r = rng;
1020 : dl 1.1 double o = origin, b = bound;
1021 :     do {
1022 : dl 1.15 consumer.accept(r.internalNextDouble(o, b));
1023 : dl 1.1 } while (++i < f);
1024 :     }
1025 :     }
1026 :     }
1027 :    
1028 :     }

Doug Lea
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