25 |
|
|
26 |
|
package java.util; |
27 |
|
|
28 |
– |
import java.security.SecureRandom; |
28 |
|
import java.util.concurrent.atomic.AtomicLong; |
29 |
< |
import java.util.Spliterator; |
29 |
> |
import java.util.function.DoubleConsumer; |
30 |
|
import java.util.function.IntConsumer; |
31 |
|
import java.util.function.LongConsumer; |
32 |
< |
import java.util.function.DoubleConsumer; |
34 |
< |
import java.util.stream.StreamSupport; |
32 |
> |
import java.util.stream.DoubleStream; |
33 |
|
import java.util.stream.IntStream; |
34 |
|
import java.util.stream.LongStream; |
35 |
< |
import java.util.stream.DoubleStream; |
35 |
> |
import java.util.stream.StreamSupport; |
36 |
|
|
37 |
|
/** |
38 |
|
* A generator of uniform pseudorandom values applicable for use in |
39 |
|
* (among other contexts) isolated parallel computations that may |
40 |
< |
* generate subtasks. Class SplittableRandom supports methods for |
40 |
> |
* generate subtasks. Class {@code SplittableRandom} supports methods for |
41 |
|
* producing pseudorandom numbers of type {@code int}, {@code long}, |
42 |
|
* and {@code double} with similar usages as for class |
43 |
|
* {@link java.util.Random} but differs in the following ways: |
52 |
|
* types and ranges, but similar properties are expected to hold, at |
53 |
|
* least approximately, for others as well. The <em>period</em> |
54 |
|
* (length of any series of generated values before it repeats) is at |
55 |
< |
* least 2<sup>64</sup>. </li> |
55 |
> |
* least 2<sup>64</sup>. |
56 |
|
* |
57 |
< |
* <li> Method {@link #split} constructs and returns a new |
57 |
> |
* <li>Method {@link #split} constructs and returns a new |
58 |
|
* SplittableRandom instance that shares no mutable state with the |
59 |
|
* current instance. However, with very high probability, the |
60 |
|
* values collectively generated by the two objects have the same |
61 |
|
* statistical properties as if the same quantity of values were |
62 |
|
* generated by a single thread using a single {@code |
63 |
< |
* SplittableRandom} object. </li> |
63 |
> |
* SplittableRandom} object. |
64 |
|
* |
65 |
|
* <li>Instances of SplittableRandom are <em>not</em> thread-safe. |
66 |
|
* They are designed to be split, not shared, across threads. For |
71 |
|
* |
72 |
|
* <li>This class provides additional methods for generating random |
73 |
|
* streams, that employ the above techniques when used in {@code |
74 |
< |
* stream.parallel()} mode.</li> |
74 |
> |
* stream.parallel()} mode. |
75 |
|
* |
76 |
|
* </ul> |
77 |
|
* |
78 |
+ |
* <p>Instances of {@code SplittableRandom} are not cryptographically |
79 |
+ |
* secure. Consider instead using {@link java.security.SecureRandom} |
80 |
+ |
* in security-sensitive applications. Additionally, |
81 |
+ |
* default-constructed instances do not use a cryptographically random |
82 |
+ |
* seed unless the {@linkplain System#getProperty system property} |
83 |
+ |
* {@code java.util.secureRandomSeed} is set to {@code true}. |
84 |
+ |
* |
85 |
|
* @author Guy Steele |
86 |
|
* @author Doug Lea |
87 |
|
* @since 1.8 |
88 |
|
*/ |
89 |
< |
public class SplittableRandom { |
85 |
< |
|
86 |
< |
/* |
87 |
< |
* File organization: First the non-public methods that constitute |
88 |
< |
* the main algorithm, then the main public methods, followed by |
89 |
< |
* some custom spliterator classes needed for stream methods. |
90 |
< |
* |
91 |
< |
* Credits: Primary algorithm and code by Guy Steele. Stream |
92 |
< |
* support methods by Doug Lea. Documentation jointly produced |
93 |
< |
* with additional help from Brian Goetz. |
94 |
< |
*/ |
89 |
> |
public final class SplittableRandom { |
90 |
|
|
91 |
|
/* |
92 |
|
* Implementation Overview. |
94 |
|
* This algorithm was inspired by the "DotMix" algorithm by |
95 |
|
* Leiserson, Schardl, and Sukha "Deterministic Parallel |
96 |
|
* Random-Number Generation for Dynamic-Multithreading Platforms", |
97 |
< |
* PPoPP 2012, but improves and extends it in several ways. |
97 |
> |
* PPoPP 2012, as well as those in "Parallel random numbers: as |
98 |
> |
* easy as 1, 2, 3" by Salmon, Morae, Dror, and Shaw, SC 2011. It |
99 |
> |
* differs mainly in simplifying and cheapening operations. |
100 |
> |
* |
101 |
> |
* The primary update step (method nextSeed()) is to add a |
102 |
> |
* constant ("gamma") to the current (64 bit) seed, forming a |
103 |
> |
* simple sequence. The seed and the gamma values for any two |
104 |
> |
* SplittableRandom instances are highly likely to be different. |
105 |
> |
* |
106 |
> |
* Methods nextLong, nextInt, and derivatives do not return the |
107 |
> |
* sequence (seed) values, but instead a hash-like bit-mix of |
108 |
> |
* their bits, producing more independently distributed sequences. |
109 |
> |
* For nextLong, the mix64 function is based on David Stafford's |
110 |
> |
* (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html) |
111 |
> |
* "Mix13" variant of the "64-bit finalizer" function in Austin |
112 |
> |
* Appleby's MurmurHash3 algorithm (see |
113 |
> |
* http://code.google.com/p/smhasher/wiki/MurmurHash3). The mix32 |
114 |
> |
* function is based on Stafford's Mix04 mix function, but returns |
115 |
> |
* the upper 32 bits cast as int. |
116 |
> |
* |
117 |
> |
* The split operation uses the current generator to form the seed |
118 |
> |
* and gamma for another SplittableRandom. To conservatively |
119 |
> |
* avoid potential correlations between seed and value generation, |
120 |
> |
* gamma selection (method mixGamma) uses different |
121 |
> |
* (Murmurhash3's) mix constants. To avoid potential weaknesses |
122 |
> |
* in bit-mixing transformations, we restrict gammas to odd values |
123 |
> |
* with at least 24 0-1 or 1-0 bit transitions. Rather than |
124 |
> |
* rejecting candidates with too few or too many bits set, method |
125 |
> |
* mixGamma flips some bits (which has the effect of mapping at |
126 |
> |
* most 4 to any given gamma value). This reduces the effective |
127 |
> |
* set of 64bit odd gamma values by about 2%, and serves as an |
128 |
> |
* automated screening for sequence constant selection that is |
129 |
> |
* left as an empirical decision in some other hashing and crypto |
130 |
> |
* algorithms. |
131 |
> |
* |
132 |
> |
* The resulting generator thus transforms a sequence in which |
133 |
> |
* (typically) many bits change on each step, with an inexpensive |
134 |
> |
* mixer with good (but less than cryptographically secure) |
135 |
> |
* avalanching. |
136 |
> |
* |
137 |
> |
* The default (no-argument) constructor, in essence, invokes |
138 |
> |
* split() for a common "defaultGen" SplittableRandom. Unlike |
139 |
> |
* other cases, this split must be performed in a thread-safe |
140 |
> |
* manner, so we use an AtomicLong to represent the seed rather |
141 |
> |
* than use an explicit SplittableRandom. To bootstrap the |
142 |
> |
* defaultGen, we start off using a seed based on current time |
143 |
> |
* unless the java.util.secureRandomSeed property is set. This |
144 |
> |
* serves as a slimmed-down (and insecure) variant of SecureRandom |
145 |
> |
* that also avoids stalls that may occur when using /dev/random. |
146 |
> |
* |
147 |
> |
* It is a relatively simple matter to apply the basic design here |
148 |
> |
* to use 128 bit seeds. However, emulating 128bit arithmetic and |
149 |
> |
* carrying around twice the state add more overhead than appears |
150 |
> |
* warranted for current usages. |
151 |
|
* |
152 |
< |
* The primary update step (see method nextSeed()) is simply to |
153 |
< |
* add a constant ("gamma") to the current seed, modulo a prime |
154 |
< |
* ("George"). However, the nextLong and nextInt methods do not |
107 |
< |
* return this value, but instead the results of bit-mixing |
108 |
< |
* transformations that produce more uniformly distributed |
109 |
< |
* sequences. |
110 |
< |
* |
111 |
< |
* "George" is the otherwise nameless (because it cannot be |
112 |
< |
* represented) prime number 2^64+13. Using a prime number larger |
113 |
< |
* than can fit in a long ensures that all possible long values |
114 |
< |
* can occur, plus 13 others that just get skipped over when they |
115 |
< |
* are encountered; see method addGammaModGeorge. For this to |
116 |
< |
* work, initial gamma values must be at least 13. |
117 |
< |
* |
118 |
< |
* The mix64 bit-mixing function called by nextLong and other |
119 |
< |
* methods computes the same value as the "64-bit finalizer" |
120 |
< |
* function in Austin Appleby's MurmurHash3 algorithm. See |
121 |
< |
* http://code.google.com/p/smhasher/wiki/MurmurHash3 , which |
122 |
< |
* comments: "The constants for the finalizers were generated by a |
123 |
< |
* simple simulated-annealing algorithm, and both avalanche all |
124 |
< |
* bits of 'h' to within 0.25% bias." |
125 |
< |
* |
126 |
< |
* The value of gamma differs for each instance across a series of |
127 |
< |
* splits, and is generated using an independent variant of the |
128 |
< |
* same algorithm, but operating across calls to split(), not |
129 |
< |
* calls to nextSeed(): Each instance carries the state of this |
130 |
< |
* generator as nextSplit. Gammas are treated as 57bit values, |
131 |
< |
* advancing by adding GAMMA_GAMMA mod GAMMA_PRIME, and bit-mixed |
132 |
< |
* with a 57-bit version of mix, using the "Mix01" multiplicative |
133 |
< |
* constants for MurmurHash3 described by David Stafford |
134 |
< |
* (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html). |
135 |
< |
* The value of GAMMA_GAMMA is arbitrary (except must be at least |
136 |
< |
* 13 and less than GAMMA_PRIME), but because it serves as the |
137 |
< |
* base of split sequences, should be subject to validation of |
138 |
< |
* consequent random number quality metrics. |
139 |
< |
* |
140 |
< |
* The mix32 function used for nextInt just consists of two of the |
141 |
< |
* five lines of mix64; avalanche testing shows that the 64-bit |
142 |
< |
* result has its top 32 bits avalanched well, though not the |
143 |
< |
* bottom 32 bits. DieHarder tests show that it is adequate for |
144 |
< |
* generating one random int from the 64-bit result of nextSeed. |
145 |
< |
* |
146 |
< |
* Support for the default (no-argument) constructor relies on an |
147 |
< |
* AtomicLong (defaultSeedGenerator) to help perform the |
148 |
< |
* equivalent of a split of a statically constructed |
149 |
< |
* SplittableRandom. Unlike other cases, this split must be |
150 |
< |
* performed in a thread-safe manner. We use |
151 |
< |
* AtomicLong.compareAndSet as the (typically) most efficient |
152 |
< |
* mechanism. To bootstrap, we start off using a SecureRandom |
153 |
< |
* initial default seed, and update using a fixed |
154 |
< |
* DEFAULT_SEED_GAMMA. The default constructor uses GAMMA_GAMMA, |
155 |
< |
* not 0, for its splitSeed argument (addGammaModGeorge(0, |
156 |
< |
* GAMMA_GAMMA) == GAMMA_GAMMA) to reflect that each is split from |
157 |
< |
* this root generator, even though the root is not explicitly |
158 |
< |
* represented as a SplittableRandom. |
159 |
< |
*/ |
160 |
< |
|
161 |
< |
/** |
162 |
< |
* The prime modulus for gamma values. |
163 |
< |
*/ |
164 |
< |
private static final long GAMMA_PRIME = (1L << 57) - 13L; |
165 |
< |
|
166 |
< |
/** |
167 |
< |
* The value for producing new gamma values. Must be greater or |
168 |
< |
* equal to 13 and less than GAMMA_PRIME. Otherwise, the value is |
169 |
< |
* arbitrary subject to validation of the resulting statistical |
170 |
< |
* quality of splits. |
171 |
< |
*/ |
172 |
< |
private static final long GAMMA_GAMMA = 0x00aae38294f712aabL; |
173 |
< |
|
174 |
< |
/** |
175 |
< |
* The seed update value for default constructors. Must be |
176 |
< |
* greater or equal to 13. Otherwise, the value is arbitrary |
177 |
< |
* subject to quality checks. |
152 |
> |
* File organization: First the non-public methods that constitute |
153 |
> |
* the main algorithm, then the main public methods, followed by |
154 |
> |
* some custom spliterator classes needed for stream methods. |
155 |
|
*/ |
179 |
– |
private static final long DEFAULT_SEED_GAMMA = 0x9e3779b97f4a7c15L; |
156 |
|
|
157 |
|
/** |
158 |
< |
* The value 13 with 64bit sign bit set. Used in the signed |
159 |
< |
* comparison in addGammaModGeorge. |
158 |
> |
* The golden ratio scaled to 64bits, used as the initial gamma |
159 |
> |
* value for (unsplit) SplittableRandoms. |
160 |
|
*/ |
161 |
< |
private static final long BOTTOM13 = 0x800000000000000DL; |
161 |
> |
private static final long GOLDEN_GAMMA = 0x9e3779b97f4a7c15L; |
162 |
|
|
163 |
|
/** |
164 |
|
* The least non-zero value returned by nextDouble(). This value |
165 |
|
* is scaled by a random value of 53 bits to produce a result. |
166 |
|
*/ |
167 |
< |
private static final double DOUBLE_UNIT = 1.0 / (1L << 53); |
167 |
> |
private static final double DOUBLE_UNIT = 0x1.0p-53; // 1.0 / (1L << 53); |
168 |
|
|
169 |
|
/** |
170 |
< |
* The next seed for default constructors. |
195 |
< |
*/ |
196 |
< |
private static final AtomicLong defaultSeedGenerator = |
197 |
< |
new AtomicLong(getInitialDefaultSeed()); |
198 |
< |
|
199 |
< |
/** |
200 |
< |
* The seed, updated only via method nextSeed. |
170 |
> |
* The seed. Updated only via method nextSeed. |
171 |
|
*/ |
172 |
|
private long seed; |
173 |
|
|
174 |
|
/** |
175 |
< |
* The constant value added to seed (mod George) on each update. |
175 |
> |
* The step value. |
176 |
|
*/ |
177 |
|
private final long gamma; |
178 |
|
|
179 |
|
/** |
180 |
< |
* The next seed to use for splits. Propagated using |
211 |
< |
* addGammaModGeorge across instances. |
212 |
< |
*/ |
213 |
< |
private final long nextSplit; |
214 |
< |
|
215 |
< |
/** |
216 |
< |
* Adds the given gamma value, g, to the given seed value s, mod |
217 |
< |
* George (2^64+13). We regard s and g as unsigned values |
218 |
< |
* (ranging from 0 to 2^64-1). We add g to s either once or twice |
219 |
< |
* (mod George) as necessary to produce an (unsigned) result less |
220 |
< |
* than 2^64. We require that g must be at least 13. This |
221 |
< |
* guarantees that if (s+g) mod George >= 2^64 then (s+g+g) mod |
222 |
< |
* George < 2^64; thus we need only a conditional, not a loop, |
223 |
< |
* to be sure of getting a representable value. |
224 |
< |
* |
225 |
< |
* Because Java comparison operators are signed, we implement this |
226 |
< |
* by conceptually offsetting seed values downwards by 2^63, so |
227 |
< |
* 0..13 is represented as Long.MIN_VALUE..BOTTOM13. |
228 |
< |
* |
229 |
< |
* @param s a seed value, viewed as a signed long |
230 |
< |
* @param g a gamma value, 13 <= g (as unsigned) |
180 |
> |
* Internal constructor used by all others except default constructor. |
181 |
|
*/ |
182 |
< |
private static long addGammaModGeorge(long s, long g) { |
183 |
< |
long p = s + g; |
184 |
< |
return (p >= s) ? p : ((p >= BOTTOM13) ? p : p + g) - 13L; |
182 |
> |
private SplittableRandom(long seed, long gamma) { |
183 |
> |
this.seed = seed; |
184 |
> |
this.gamma = gamma; |
185 |
|
} |
186 |
|
|
187 |
|
/** |
188 |
< |
* Returns a bit-mixed transformation of its argument. |
239 |
< |
* See above for explanation. |
188 |
> |
* Computes Stafford variant 13 of 64bit mix function. |
189 |
|
*/ |
190 |
|
private static long mix64(long z) { |
191 |
< |
z ^= (z >>> 33); |
192 |
< |
z *= 0xff51afd7ed558ccdL; |
193 |
< |
z ^= (z >>> 33); |
245 |
< |
z *= 0xc4ceb9fe1a85ec53L; |
246 |
< |
z ^= (z >>> 33); |
247 |
< |
return z; |
191 |
> |
z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L; |
192 |
> |
z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL; |
193 |
> |
return z ^ (z >>> 31); |
194 |
|
} |
195 |
|
|
196 |
|
/** |
197 |
< |
* Returns a bit-mixed int transformation of its argument. |
252 |
< |
* See above for explanation. |
197 |
> |
* Returns the 32 high bits of Stafford variant 4 mix64 function as int. |
198 |
|
*/ |
199 |
|
private static int mix32(long z) { |
200 |
< |
z ^= (z >>> 33); |
201 |
< |
z *= 0xc4ceb9fe1a85ec53L; |
257 |
< |
return (int)(z >>> 32); |
258 |
< |
} |
259 |
< |
|
260 |
< |
/** |
261 |
< |
* Returns a 57-bit mixed transformation of its argument. See |
262 |
< |
* above for explanation. |
263 |
< |
*/ |
264 |
< |
private static long mix57(long z) { |
265 |
< |
z ^= (z >>> 33); |
266 |
< |
z *= 0x7fb5d329728ea185L; |
267 |
< |
z &= 0x01FFFFFFFFFFFFFFL; |
268 |
< |
z ^= (z >>> 33); |
269 |
< |
z *= 0x81dadef4bc2dd44dL; |
270 |
< |
z &= 0x01FFFFFFFFFFFFFFL; |
271 |
< |
z ^= (z >>> 33); |
272 |
< |
return z; |
200 |
> |
z = (z ^ (z >>> 33)) * 0x62a9d9ed799705f5L; |
201 |
> |
return (int)(((z ^ (z >>> 28)) * 0xcb24d0a5c88c35b3L) >>> 32); |
202 |
|
} |
203 |
|
|
204 |
|
/** |
205 |
< |
* Internal constructor used by all other constructors and by |
277 |
< |
* method split. Establishes the initial seed for this instance, |
278 |
< |
* and uses the given splitSeed to establish gamma, as well as the |
279 |
< |
* nextSplit to use by this instance. The loop to skip ineligible |
280 |
< |
* gammas very rarely iterates, and does so at most 13 times. |
205 |
> |
* Returns the gamma value to use for a new split 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 += GAMMA_GAMMA; |
212 |
< |
if (s >= GAMMA_PRIME) |
288 |
< |
s -= GAMMA_PRIME; |
289 |
< |
g = mix57(s); |
290 |
< |
} while (g < 13L); |
291 |
< |
this.gamma = g; |
292 |
< |
this.nextSplit = s; |
207 |
> |
private static long mixGamma(long z) { |
208 |
> |
z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL; // MurmurHash3 mix constants |
209 |
> |
z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L; |
210 |
> |
z = (z ^ (z >>> 33)) | 1L; // force to be odd |
211 |
> |
int n = Long.bitCount(z ^ (z >>> 1)); // ensure enough transitions |
212 |
> |
return (n < 24) ? z ^ 0xaaaaaaaaaaaaaaaaL : z; |
213 |
|
} |
214 |
|
|
215 |
|
/** |
216 |
< |
* Updates in-place and returns seed. |
297 |
< |
* See above for explanation. |
216 |
> |
* Adds gamma to seed. |
217 |
|
*/ |
218 |
|
private long nextSeed() { |
219 |
< |
return seed = addGammaModGeorge(seed, gamma); |
301 |
< |
} |
302 |
< |
|
303 |
< |
/** |
304 |
< |
* Atomically updates and returns next seed for default constructor. |
305 |
< |
*/ |
306 |
< |
private static long nextDefaultSeed() { |
307 |
< |
long oldSeed, newSeed; |
308 |
< |
do { |
309 |
< |
oldSeed = defaultSeedGenerator.get(); |
310 |
< |
newSeed = addGammaModGeorge(oldSeed, DEFAULT_SEED_GAMMA); |
311 |
< |
} while (!defaultSeedGenerator.compareAndSet(oldSeed, newSeed)); |
312 |
< |
return mix64(newSeed); |
219 |
> |
return seed += gamma; |
220 |
|
} |
221 |
|
|
222 |
< |
/** |
223 |
< |
* Returns an initial default seed. |
224 |
< |
*/ |
225 |
< |
private static long getInitialDefaultSeed() { |
226 |
< |
byte[] seedBytes = java.security.SecureRandom.getSeed(8); |
227 |
< |
long s = (long)(seedBytes[0]) & 0xffL; |
228 |
< |
for (int i = 1; i < 8; ++i) |
229 |
< |
s = (s << 8) | ((long)(seedBytes[i]) & 0xffL); |
230 |
< |
return s; |
222 |
> |
// IllegalArgumentException messages |
223 |
> |
static final String BAD_BOUND = "bound must be positive"; |
224 |
> |
static final String BAD_RANGE = "bound must be greater than origin"; |
225 |
> |
static final String BAD_SIZE = "size must be non-negative"; |
226 |
> |
|
227 |
> |
/** |
228 |
> |
* The seed generator for default constructors. |
229 |
> |
*/ |
230 |
> |
private static final AtomicLong defaultGen |
231 |
> |
= new AtomicLong(mix64(System.currentTimeMillis()) ^ |
232 |
> |
mix64(System.nanoTime())); |
233 |
> |
|
234 |
> |
// at end of <clinit> to survive static initialization circularity |
235 |
> |
static { |
236 |
> |
if (java.security.AccessController.doPrivileged( |
237 |
> |
new java.security.PrivilegedAction<Boolean>() { |
238 |
> |
public Boolean run() { |
239 |
> |
return Boolean.getBoolean("java.util.secureRandomSeed"); |
240 |
> |
}})) { |
241 |
> |
byte[] seedBytes = java.security.SecureRandom.getSeed(8); |
242 |
> |
long s = (long)seedBytes[0] & 0xffL; |
243 |
> |
for (int i = 1; i < 8; ++i) |
244 |
> |
s = (s << 8) | ((long)seedBytes[i] & 0xffL); |
245 |
> |
defaultGen.set(s); |
246 |
> |
} |
247 |
|
} |
248 |
|
|
249 |
|
/* |
365 |
|
* @param seed the initial seed |
366 |
|
*/ |
367 |
|
public SplittableRandom(long seed) { |
368 |
< |
this(seed, 0L); |
368 |
> |
this(seed, GOLDEN_GAMMA); |
369 |
|
} |
370 |
|
|
371 |
|
/** |
374 |
|
* of those of any other instances in the current program; and |
375 |
|
* may, and typically does, vary across program invocations. |
376 |
|
*/ |
377 |
< |
public SplittableRandom() { |
378 |
< |
this(nextDefaultSeed(), GAMMA_GAMMA); |
377 |
> |
public SplittableRandom() { // emulate defaultGen.split() |
378 |
> |
long s = defaultGen.getAndAdd(GOLDEN_GAMMA << 1); |
379 |
> |
this.seed = mix64(s); |
380 |
> |
this.gamma = mixGamma(s + GOLDEN_GAMMA); |
381 |
|
} |
382 |
|
|
383 |
|
/** |
395 |
|
* @return the new SplittableRandom instance |
396 |
|
*/ |
397 |
|
public SplittableRandom split() { |
398 |
< |
return new SplittableRandom(nextSeed(), nextSplit); |
398 |
> |
return new SplittableRandom(nextLong(), mixGamma(nextSeed())); |
399 |
> |
} |
400 |
> |
|
401 |
> |
/** |
402 |
> |
* Fills a user-supplied byte array with generated pseudorandom bytes. |
403 |
> |
* |
404 |
> |
* @param bytes the byte array to fill with pseudorandom bytes |
405 |
> |
* @throws NullPointerException if bytes is null |
406 |
> |
* @since 10 |
407 |
> |
*/ |
408 |
> |
public void nextBytes(byte[] bytes) { |
409 |
> |
int i = 0; |
410 |
> |
int len = bytes.length; |
411 |
> |
for (int words = len >> 3; words--> 0; ) { |
412 |
> |
long rnd = nextLong(); |
413 |
> |
for (int n = 8; n--> 0; rnd >>>= Byte.SIZE) |
414 |
> |
bytes[i++] = (byte)rnd; |
415 |
> |
} |
416 |
> |
if (i < len) |
417 |
> |
for (long rnd = nextLong(); i < len; rnd >>>= Byte.SIZE) |
418 |
> |
bytes[i++] = (byte)rnd; |
419 |
|
} |
420 |
|
|
421 |
|
/** |
431 |
|
* Returns a pseudorandom {@code int} value between zero (inclusive) |
432 |
|
* and the specified bound (exclusive). |
433 |
|
* |
434 |
< |
* @param bound the bound on the random number to be returned. Must be |
490 |
< |
* positive. |
434 |
> |
* @param bound the upper bound (exclusive). Must be positive. |
435 |
|
* @return a pseudorandom {@code int} value between zero |
436 |
|
* (inclusive) and the bound (exclusive) |
437 |
< |
* @throws IllegalArgumentException if the bound is less than zero |
437 |
> |
* @throws IllegalArgumentException if {@code bound} is not positive |
438 |
|
*/ |
439 |
|
public int nextInt(int bound) { |
440 |
|
if (bound <= 0) |
441 |
< |
throw new IllegalArgumentException("bound must be positive"); |
441 |
> |
throw new IllegalArgumentException(BAD_BOUND); |
442 |
|
// Specialize internalNextInt for origin 0 |
443 |
|
int r = mix32(nextSeed()); |
444 |
|
int m = bound - 1; |
466 |
|
*/ |
467 |
|
public int nextInt(int origin, int bound) { |
468 |
|
if (origin >= bound) |
469 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
469 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
470 |
|
return internalNextInt(origin, bound); |
471 |
|
} |
472 |
|
|
483 |
|
* Returns a pseudorandom {@code long} value between zero (inclusive) |
484 |
|
* and the specified bound (exclusive). |
485 |
|
* |
486 |
< |
* @param bound the bound on the random number to be returned. Must be |
543 |
< |
* positive. |
486 |
> |
* @param bound the upper bound (exclusive). Must be positive. |
487 |
|
* @return a pseudorandom {@code long} value between zero |
488 |
|
* (inclusive) and the bound (exclusive) |
489 |
< |
* @throws IllegalArgumentException if {@code bound} is less than zero |
489 |
> |
* @throws IllegalArgumentException if {@code bound} is not positive |
490 |
|
*/ |
491 |
|
public long nextLong(long bound) { |
492 |
|
if (bound <= 0) |
493 |
< |
throw new IllegalArgumentException("bound must be positive"); |
493 |
> |
throw new IllegalArgumentException(BAD_BOUND); |
494 |
|
// Specialize internalNextLong for origin 0 |
495 |
|
long r = mix64(nextSeed()); |
496 |
|
long m = bound - 1; |
518 |
|
*/ |
519 |
|
public long nextLong(long origin, long bound) { |
520 |
|
if (origin >= bound) |
521 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
521 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
522 |
|
return internalNextLong(origin, bound); |
523 |
|
} |
524 |
|
|
527 |
|
* (inclusive) and one (exclusive). |
528 |
|
* |
529 |
|
* @return a pseudorandom {@code double} value between zero |
530 |
< |
* (inclusive) and one (exclusive) |
530 |
> |
* (inclusive) and one (exclusive) |
531 |
|
*/ |
532 |
|
public double nextDouble() { |
533 |
|
return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT; |
537 |
|
* Returns a pseudorandom {@code double} value between 0.0 |
538 |
|
* (inclusive) and the specified bound (exclusive). |
539 |
|
* |
540 |
< |
* @param bound the bound on the random number to be returned. Must be |
598 |
< |
* positive. |
540 |
> |
* @param bound the upper bound (exclusive). Must be positive. |
541 |
|
* @return a pseudorandom {@code double} value between zero |
542 |
|
* (inclusive) and the bound (exclusive) |
543 |
< |
* @throws IllegalArgumentException if {@code bound} is less than zero |
543 |
> |
* @throws IllegalArgumentException if {@code bound} is not positive |
544 |
|
*/ |
545 |
|
public double nextDouble(double bound) { |
546 |
|
if (!(bound > 0.0)) |
547 |
< |
throw new IllegalArgumentException("bound must be positive"); |
547 |
> |
throw new IllegalArgumentException(BAD_BOUND); |
548 |
|
double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound; |
549 |
|
return (result < bound) ? result : // correct for rounding |
550 |
|
Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
555 |
|
* origin (inclusive) and bound (exclusive). |
556 |
|
* |
557 |
|
* @param origin the least value returned |
558 |
< |
* @param bound the upper bound |
558 |
> |
* @param bound the upper bound (exclusive) |
559 |
|
* @return a pseudorandom {@code double} value between the origin |
560 |
|
* (inclusive) and the bound (exclusive) |
561 |
|
* @throws IllegalArgumentException if {@code origin} is greater than |
563 |
|
*/ |
564 |
|
public double nextDouble(double origin, double bound) { |
565 |
|
if (!(origin < bound)) |
566 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
566 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
567 |
|
return internalNextDouble(origin, bound); |
568 |
|
} |
569 |
|
|
580 |
|
// maintenance purposes the small differences across forms. |
581 |
|
|
582 |
|
/** |
583 |
< |
* Returns a stream producing the given {@code streamSize} number of |
584 |
< |
* pseudorandom {@code int} values. |
583 |
> |
* Returns a stream producing the given {@code streamSize} number |
584 |
> |
* of pseudorandom {@code int} values from this generator and/or |
585 |
> |
* one split from it. |
586 |
|
* |
587 |
|
* @param streamSize the number of values to generate |
588 |
|
* @return a stream of pseudorandom {@code int} values |
591 |
|
*/ |
592 |
|
public IntStream ints(long streamSize) { |
593 |
|
if (streamSize < 0L) |
594 |
< |
throw new IllegalArgumentException("negative Stream size"); |
594 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
595 |
|
return StreamSupport.intStream |
596 |
|
(new RandomIntsSpliterator |
597 |
|
(this, 0L, streamSize, Integer.MAX_VALUE, 0), |
600 |
|
|
601 |
|
/** |
602 |
|
* Returns an effectively unlimited stream of pseudorandom {@code int} |
603 |
< |
* values. |
603 |
> |
* values from this generator and/or one split from it. |
604 |
|
* |
605 |
|
* @implNote This method is implemented to be equivalent to {@code |
606 |
|
* ints(Long.MAX_VALUE)}. |
615 |
|
} |
616 |
|
|
617 |
|
/** |
618 |
< |
* Returns a stream producing the given {@code streamSize} number of |
619 |
< |
* pseudorandom {@code int} values, each conforming to the given |
620 |
< |
* origin and bound. |
618 |
> |
* Returns a stream producing the given {@code streamSize} number |
619 |
> |
* of pseudorandom {@code int} values from this generator and/or one split |
620 |
> |
* from it; each value conforms to the given origin (inclusive) and bound |
621 |
> |
* (exclusive). |
622 |
|
* |
623 |
|
* @param streamSize the number of values to generate |
624 |
< |
* @param randomNumberOrigin the origin of each random value |
625 |
< |
* @param randomNumberBound the bound of each random value |
624 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
625 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
626 |
|
* @return a stream of pseudorandom {@code int} values, |
627 |
< |
* each with the given origin and bound |
627 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
628 |
|
* @throws IllegalArgumentException if {@code streamSize} is |
629 |
|
* less than zero, or {@code randomNumberOrigin} |
630 |
|
* is greater than or equal to {@code randomNumberBound} |
632 |
|
public IntStream ints(long streamSize, int randomNumberOrigin, |
633 |
|
int randomNumberBound) { |
634 |
|
if (streamSize < 0L) |
635 |
< |
throw new IllegalArgumentException("negative Stream size"); |
635 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
636 |
|
if (randomNumberOrigin >= randomNumberBound) |
637 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
637 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
638 |
|
return StreamSupport.intStream |
639 |
|
(new RandomIntsSpliterator |
640 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
643 |
|
|
644 |
|
/** |
645 |
|
* Returns an effectively unlimited stream of pseudorandom {@code |
646 |
< |
* int} values, each conforming to the given origin and bound. |
646 |
> |
* int} values from this generator and/or one split from it; each value |
647 |
> |
* conforms to the given origin (inclusive) and bound (exclusive). |
648 |
|
* |
649 |
|
* @implNote This method is implemented to be equivalent to {@code |
650 |
|
* ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
651 |
|
* |
652 |
< |
* @param randomNumberOrigin the origin of each random value |
653 |
< |
* @param randomNumberBound the bound of each random value |
652 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
653 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
654 |
|
* @return a stream of pseudorandom {@code int} values, |
655 |
< |
* each with the given origin and bound |
655 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
656 |
|
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
657 |
|
* is greater than or equal to {@code randomNumberBound} |
658 |
|
*/ |
659 |
|
public IntStream ints(int randomNumberOrigin, int randomNumberBound) { |
660 |
|
if (randomNumberOrigin >= randomNumberBound) |
661 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
661 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
662 |
|
return StreamSupport.intStream |
663 |
|
(new RandomIntsSpliterator |
664 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
666 |
|
} |
667 |
|
|
668 |
|
/** |
669 |
< |
* Returns a stream producing the given {@code streamSize} number of |
670 |
< |
* pseudorandom {@code long} values. |
669 |
> |
* Returns a stream producing the given {@code streamSize} number |
670 |
> |
* of pseudorandom {@code long} values from this generator and/or |
671 |
> |
* one split from it. |
672 |
|
* |
673 |
|
* @param streamSize the number of values to generate |
674 |
|
* @return a stream of pseudorandom {@code long} values |
677 |
|
*/ |
678 |
|
public LongStream longs(long streamSize) { |
679 |
|
if (streamSize < 0L) |
680 |
< |
throw new IllegalArgumentException("negative Stream size"); |
680 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
681 |
|
return StreamSupport.longStream |
682 |
|
(new RandomLongsSpliterator |
683 |
|
(this, 0L, streamSize, Long.MAX_VALUE, 0L), |
685 |
|
} |
686 |
|
|
687 |
|
/** |
688 |
< |
* Returns an effectively unlimited stream of pseudorandom {@code long} |
689 |
< |
* values. |
688 |
> |
* Returns an effectively unlimited stream of pseudorandom {@code |
689 |
> |
* long} values from this generator and/or one split from it. |
690 |
|
* |
691 |
|
* @implNote This method is implemented to be equivalent to {@code |
692 |
|
* longs(Long.MAX_VALUE)}. |
702 |
|
|
703 |
|
/** |
704 |
|
* Returns a stream producing the given {@code streamSize} number of |
705 |
< |
* pseudorandom {@code long} values, each conforming to the |
706 |
< |
* given origin and bound. |
705 |
> |
* pseudorandom {@code long} values from this generator and/or one split |
706 |
> |
* from it; each value conforms to the given origin (inclusive) and bound |
707 |
> |
* (exclusive). |
708 |
|
* |
709 |
|
* @param streamSize the number of values to generate |
710 |
< |
* @param randomNumberOrigin the origin of each random value |
711 |
< |
* @param randomNumberBound the bound of each random value |
710 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
711 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
712 |
|
* @return a stream of pseudorandom {@code long} values, |
713 |
< |
* each with the given origin and bound |
713 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
714 |
|
* @throws IllegalArgumentException if {@code streamSize} is |
715 |
|
* less than zero, or {@code randomNumberOrigin} |
716 |
|
* is greater than or equal to {@code randomNumberBound} |
718 |
|
public LongStream longs(long streamSize, long randomNumberOrigin, |
719 |
|
long randomNumberBound) { |
720 |
|
if (streamSize < 0L) |
721 |
< |
throw new IllegalArgumentException("negative Stream size"); |
721 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
722 |
|
if (randomNumberOrigin >= randomNumberBound) |
723 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
723 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
724 |
|
return StreamSupport.longStream |
725 |
|
(new RandomLongsSpliterator |
726 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
729 |
|
|
730 |
|
/** |
731 |
|
* Returns an effectively unlimited stream of pseudorandom {@code |
732 |
< |
* long} values, each conforming to the given origin and bound. |
732 |
> |
* long} values from this generator and/or one split from it; each value |
733 |
> |
* conforms to the given origin (inclusive) and bound (exclusive). |
734 |
|
* |
735 |
|
* @implNote This method is implemented to be equivalent to {@code |
736 |
|
* longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
737 |
|
* |
738 |
< |
* @param randomNumberOrigin the origin of each random value |
739 |
< |
* @param randomNumberBound the bound of each random value |
738 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
739 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
740 |
|
* @return a stream of pseudorandom {@code long} values, |
741 |
< |
* each with the given origin and bound |
741 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
742 |
|
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
743 |
|
* is greater than or equal to {@code randomNumberBound} |
744 |
|
*/ |
745 |
|
public LongStream longs(long randomNumberOrigin, long randomNumberBound) { |
746 |
|
if (randomNumberOrigin >= randomNumberBound) |
747 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
747 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
748 |
|
return StreamSupport.longStream |
749 |
|
(new RandomLongsSpliterator |
750 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
753 |
|
|
754 |
|
/** |
755 |
|
* Returns a stream producing the given {@code streamSize} number of |
756 |
< |
* pseudorandom {@code double} values, each between zero |
757 |
< |
* (inclusive) and one (exclusive). |
756 |
> |
* pseudorandom {@code double} values from this generator and/or one split |
757 |
> |
* from it; each value is between zero (inclusive) and one (exclusive). |
758 |
|
* |
759 |
|
* @param streamSize the number of values to generate |
760 |
|
* @return a stream of {@code double} values |
763 |
|
*/ |
764 |
|
public DoubleStream doubles(long streamSize) { |
765 |
|
if (streamSize < 0L) |
766 |
< |
throw new IllegalArgumentException("negative Stream size"); |
766 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
767 |
|
return StreamSupport.doubleStream |
768 |
|
(new RandomDoublesSpliterator |
769 |
|
(this, 0L, streamSize, Double.MAX_VALUE, 0.0), |
772 |
|
|
773 |
|
/** |
774 |
|
* Returns an effectively unlimited stream of pseudorandom {@code |
775 |
< |
* double} values, each between zero (inclusive) and one |
776 |
< |
* (exclusive). |
775 |
> |
* double} values from this generator and/or one split from it; each value |
776 |
> |
* is between zero (inclusive) and one (exclusive). |
777 |
|
* |
778 |
|
* @implNote This method is implemented to be equivalent to {@code |
779 |
|
* doubles(Long.MAX_VALUE)}. |
789 |
|
|
790 |
|
/** |
791 |
|
* Returns a stream producing the given {@code streamSize} number of |
792 |
< |
* pseudorandom {@code double} values, each conforming to the |
793 |
< |
* given origin and bound. |
792 |
> |
* pseudorandom {@code double} values from this generator and/or one split |
793 |
> |
* from it; each value conforms to the given origin (inclusive) and bound |
794 |
> |
* (exclusive). |
795 |
|
* |
796 |
|
* @param streamSize the number of values to generate |
797 |
< |
* @param randomNumberOrigin the origin of each random value |
798 |
< |
* @param randomNumberBound the bound of each random value |
797 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
798 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
799 |
|
* @return a stream of pseudorandom {@code double} values, |
800 |
< |
* each with the given origin and bound |
800 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
801 |
|
* @throws IllegalArgumentException if {@code streamSize} is |
802 |
< |
* less than zero |
854 |
< |
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
802 |
> |
* less than zero, or {@code randomNumberOrigin} |
803 |
|
* is greater than or equal to {@code randomNumberBound} |
804 |
|
*/ |
805 |
|
public DoubleStream doubles(long streamSize, double randomNumberOrigin, |
806 |
|
double randomNumberBound) { |
807 |
|
if (streamSize < 0L) |
808 |
< |
throw new IllegalArgumentException("negative Stream size"); |
808 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
809 |
|
if (!(randomNumberOrigin < randomNumberBound)) |
810 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
810 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
811 |
|
return StreamSupport.doubleStream |
812 |
|
(new RandomDoublesSpliterator |
813 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
816 |
|
|
817 |
|
/** |
818 |
|
* Returns an effectively unlimited stream of pseudorandom {@code |
819 |
< |
* double} values, each conforming to the given origin and bound. |
819 |
> |
* double} values from this generator and/or one split from it; each value |
820 |
> |
* conforms to the given origin (inclusive) and bound (exclusive). |
821 |
|
* |
822 |
|
* @implNote This method is implemented to be equivalent to {@code |
823 |
|
* doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
824 |
|
* |
825 |
< |
* @param randomNumberOrigin the origin of each random value |
826 |
< |
* @param randomNumberBound the bound of each random value |
825 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
826 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
827 |
|
* @return a stream of pseudorandom {@code double} values, |
828 |
< |
* each with the given origin and bound |
828 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
829 |
|
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
830 |
|
* is greater than or equal to {@code randomNumberBound} |
831 |
|
*/ |
832 |
|
public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) { |
833 |
|
if (!(randomNumberOrigin < randomNumberBound)) |
834 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
834 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
835 |
|
return StreamSupport.doubleStream |
836 |
|
(new RandomDoublesSpliterator |
837 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
846 |
|
* approach. The long and double versions of this class are |
847 |
|
* identical except for types. |
848 |
|
*/ |
849 |
< |
static final class RandomIntsSpliterator implements Spliterator.OfInt { |
849 |
> |
private static final class RandomIntsSpliterator |
850 |
> |
implements Spliterator.OfInt { |
851 |
|
final SplittableRandom rng; |
852 |
|
long index; |
853 |
|
final long fence; |
890 |
|
long i = index, f = fence; |
891 |
|
if (i < f) { |
892 |
|
index = f; |
893 |
+ |
SplittableRandom r = rng; |
894 |
|
int o = origin, b = bound; |
895 |
|
do { |
896 |
< |
consumer.accept(rng.internalNextInt(o, b)); |
896 |
> |
consumer.accept(r.internalNextInt(o, b)); |
897 |
|
} while (++i < f); |
898 |
|
} |
899 |
|
} |
902 |
|
/** |
903 |
|
* Spliterator for long streams. |
904 |
|
*/ |
905 |
< |
static final class RandomLongsSpliterator implements Spliterator.OfLong { |
905 |
> |
private static final class RandomLongsSpliterator |
906 |
> |
implements Spliterator.OfLong { |
907 |
|
final SplittableRandom rng; |
908 |
|
long index; |
909 |
|
final long fence; |
946 |
|
long i = index, f = fence; |
947 |
|
if (i < f) { |
948 |
|
index = f; |
949 |
+ |
SplittableRandom r = rng; |
950 |
|
long o = origin, b = bound; |
951 |
|
do { |
952 |
< |
consumer.accept(rng.internalNextLong(o, b)); |
952 |
> |
consumer.accept(r.internalNextLong(o, b)); |
953 |
|
} while (++i < f); |
954 |
|
} |
955 |
|
} |
959 |
|
/** |
960 |
|
* Spliterator for double streams. |
961 |
|
*/ |
962 |
< |
static final class RandomDoublesSpliterator implements Spliterator.OfDouble { |
962 |
> |
private static final class RandomDoublesSpliterator |
963 |
> |
implements Spliterator.OfDouble { |
964 |
|
final SplittableRandom rng; |
965 |
|
long index; |
966 |
|
final long fence; |
1003 |
|
long i = index, f = fence; |
1004 |
|
if (i < f) { |
1005 |
|
index = f; |
1006 |
+ |
SplittableRandom r = rng; |
1007 |
|
double o = origin, b = bound; |
1008 |
|
do { |
1009 |
< |
consumer.accept(rng.internalNextDouble(o, b)); |
1009 |
> |
consumer.accept(r.internalNextDouble(o, b)); |
1010 |
|
} while (++i < f); |
1011 |
|
} |
1012 |
|
} |