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package java.util; |
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import java.net.NetworkInterface; |
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import java.util.concurrent.atomic.AtomicLong; |
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import java.util.Spliterator; |
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import java.util.function.IntConsumer; |
31 |
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import java.util.function.LongConsumer; |
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import java.util.function.DoubleConsumer; |
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import java.util.stream.LongStream; |
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import java.util.stream.DoubleStream; |
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/** |
39 |
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* A generator of uniform pseudorandom values applicable for use in |
40 |
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* (among other contexts) isolated parallel computations that may |
41 |
< |
* generate subtasks. Class SplittableRandom supports methods for |
42 |
< |
* producing pseudorandom nunmbers of type {@code int}, {@code long}, |
41 |
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* generate subtasks. Class {@code SplittableRandom} supports methods for |
42 |
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* producing pseudorandom numbers of type {@code int}, {@code long}, |
43 |
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* and {@code double} with similar usages as for class |
44 |
< |
* {@link java.util.Random} but differs in the following ways: <ul> |
44 |
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* {@link java.util.Random} but differs in the following ways: |
45 |
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* |
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* <ul> |
47 |
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* |
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* <li>Series of generated values pass the DieHarder suite testing |
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* independence and uniformity properties of random number generators. |
51 |
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* href="http://www.phy.duke.edu/~rgb/General/dieharder.php"> version |
52 |
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* 3.31.1</a>.) These tests validate only the methods for certain |
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* types and ranges, but similar properties are expected to hold, at |
54 |
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* least approximately, for others as well. </li> |
54 |
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* least approximately, for others as well. The <em>period</em> |
55 |
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* (length of any series of generated values before it repeats) is at |
56 |
> |
* least 2<sup>64</sup>. </li> |
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* |
58 |
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* <li> Method {@link #split} constructs and returns a new |
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* SplittableRandom instance that shares no mutable state with the |
60 |
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* current instance. However, with very high probability, the set of |
61 |
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* values collectively generated by the two objects has the same |
60 |
> |
* current instance. However, with very high probability, the |
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* values collectively generated by the two objects have the same |
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* statistical properties as if the same quantity of values were |
63 |
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* generated by a single thread using a single {@code |
64 |
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* SplittableRandom} object. </li> |
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* |
77 |
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* </ul> |
78 |
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* |
79 |
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* <p>Instances of {@code SplittableRandom} are not cryptographically |
80 |
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* secure. Consider instead using {@link java.security.SecureRandom} |
81 |
+ |
* in security-sensitive applications. Additionally, |
82 |
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* default-constructed instances do not use a cryptographically random |
83 |
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* seed unless the {@linkplain System#getProperty system property} |
84 |
+ |
* {@code java.util.secureRandomSeed} is set to {@code true}. |
85 |
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* |
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* @author Guy Steele |
87 |
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* @author Doug Lea |
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* @since 1.8 |
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*/ |
90 |
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public class SplittableRandom { |
81 |
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|
82 |
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/* |
83 |
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* File organization: First the non-public methods that constitute |
84 |
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* the main algorithm, then the main public methods, followed by |
85 |
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* some custom spliterator classes needed for stream methods. |
86 |
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* |
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* Credits: Primary algorithm and code by Guy Steele. Stream |
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* support methods by Doug Lea. Documentation jointly produced |
89 |
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* with additional help from Brian Goetz. |
90 |
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*/ |
90 |
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public final class SplittableRandom { |
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|
92 |
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/* |
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* Implementation Overview. |
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* This algorithm was inspired by the "DotMix" algorithm by |
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* Leiserson, Schardl, and Sukha "Deterministic Parallel |
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* Random-Number Generation for Dynamic-Multithreading Platforms", |
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< |
* PPoPP 2012, but improves and extends it in several ways. |
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* PPoPP 2012, as well as those in "Parallel random numbers: as |
99 |
> |
* easy as 1, 2, 3" by Salmon, Morae, Dror, and Shaw, SC 2011. It |
100 |
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* differs mainly in simplifying and cheapening operations. |
101 |
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* |
102 |
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* The primary update step (method nextSeed()) is to add a |
103 |
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* constant ("gamma") to the current (64 bit) seed, forming a |
104 |
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* simple sequence. The seed and the gamma values for any two |
105 |
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* SplittableRandom instances are highly likely to be different. |
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* |
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* Methods nextLong, nextInt, and derivatives do not return the |
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* sequence (seed) values, but instead a hash-like bit-mix of |
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* their bits, producing more independently distributed sequences. |
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* For nextLong, the mix64 function is based on David Stafford's |
111 |
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* (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html) |
112 |
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* "Mix13" variant of the "64-bit finalizer" function in Austin |
113 |
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* Appleby's MurmurHash3 algorithm See |
114 |
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* http://code.google.com/p/smhasher/wiki/MurmurHash3 . The mix32 |
115 |
> |
* function is based on Stafford's Mix04 mix function, but returns |
116 |
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* the upper 32 bits cast as int. |
117 |
> |
* |
118 |
> |
* The split operation uses the current generator to form the seed |
119 |
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* and gamma for another SplittableRandom. To conservatively |
120 |
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* avoid potential correlations between seed and value generation, |
121 |
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* gamma selection (method mixGamma) uses different |
122 |
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* (Murmurhash3's) mix constants. To avoid potential weaknesses |
123 |
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* in bit-mixing transformations, we restrict gammas to odd values |
124 |
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* with at least 24 0-1 or 1-0 bit transitions. Rather than |
125 |
> |
* rejecting candidates with too few or too many bits set, method |
126 |
> |
* mixGamma flips some bits (which has the effect of mapping at |
127 |
> |
* most 4 to any given gamma value). This reduces the effective |
128 |
> |
* set of 64bit odd gamma values by about 2%, and serves as an |
129 |
> |
* automated screening for sequence constant selection that is |
130 |
> |
* left as an empirical decision in some other hashing and crypto |
131 |
> |
* algorithms. |
132 |
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* |
133 |
> |
* The resulting generator thus transforms a sequence in which |
134 |
> |
* (typically) many bits change on each step, with an inexpensive |
135 |
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* mixer with good (but less than cryptographically secure) |
136 |
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* avalanching. |
137 |
> |
* |
138 |
> |
* The default (no-argument) constructor, in essence, invokes |
139 |
> |
* split() for a common "defaultGen" SplittableRandom. Unlike |
140 |
> |
* other cases, this split must be performed in a thread-safe |
141 |
> |
* manner, so we use an AtomicLong to represent the seed rather |
142 |
> |
* than use an explicit SplittableRandom. To bootstrap the |
143 |
> |
* defaultGen, we start off using a seed based on current time and |
144 |
> |
* network interface address unless the java.util.secureRandomSeed |
145 |
> |
* property is set. This serves as a slimmed-down (and insecure) |
146 |
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* variant of SecureRandom that also avoids stalls that may occur |
147 |
> |
* when using /dev/random. |
148 |
> |
* |
149 |
> |
* It is a relatively simple matter to apply the basic design here |
150 |
> |
* to use 128 bit seeds. However, emulating 128bit arithmetic and |
151 |
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* carrying around twice the state add more overhead than appears |
152 |
> |
* warranted for current usages. |
153 |
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* |
154 |
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* The primary update step is simply to add a constant ("gamma") |
155 |
< |
* to the current seed, modulo a prime ("George"). However, the |
156 |
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* nextLong and nextInt methods do not return this value, but |
157 |
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* instead the results of bit-mixing transformations that produce |
104 |
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* more uniformly distributed sequences. |
105 |
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* |
106 |
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* "George" is the otherwise nameless (because it cannot be |
107 |
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* represented) prime number 2^64+13. Using a prime number larger |
108 |
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* than can fit in a long ensures that all possible long values |
109 |
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* can occur, plus 13 others that just get skipped over when they |
110 |
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* are encountered; see method addGammaModGeorge. For this to |
111 |
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* work, initial gamma values must be at least 13. |
112 |
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* |
113 |
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* The value of gamma differs for each instance across a series of |
114 |
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* splits, and is generated using a slightly stripped-down variant |
115 |
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* of the same algorithm, but operating across calls to split(), |
116 |
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* not calls to nextSeed(): Each instance carries the state of |
117 |
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* this generator as nextSplit, and uses mix64(nextSplit) as its |
118 |
< |
* own gamma value. Computations of gammas themselves use a fixed |
119 |
< |
* constant as the second argument to the addGammaModGeorge |
120 |
< |
* function, GAMMA_GAMMA, a "genuinely random" number from a |
121 |
< |
* radioactive decay reading (obtained from |
122 |
< |
* http://www.fourmilab.ch/hotbits/) meeting the above range |
123 |
< |
* constraint. Using a fixed constant maintains the invariant that |
124 |
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* the value of gamma is the same for every instance that is at |
125 |
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* the same split-distance from their common root. (Note: there is |
126 |
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* nothing especially magic about obtaining this constant from a |
127 |
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* "truly random" physical source rather than just choosing one |
128 |
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* arbitrarily; using "hotbits" was merely an aesthetically pleasing |
129 |
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* choice. In either case, good statistical behavior of the |
130 |
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* algorithm should be, and was, verified by using the DieHarder |
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* test suite.) |
132 |
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* |
133 |
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* The mix64 bit-mixing function called by nextLong and other |
134 |
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* methods computes the same value as the "64-bit finalizer" |
135 |
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* function in Austin Appleby's MurmurHash3 algorithm. See |
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* http://code.google.com/p/smhasher/wiki/MurmurHash3 , which |
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* comments: "The constants for the finalizers were generated by a |
138 |
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* simple simulated-annealing algorithm, and both avalanche all |
139 |
< |
* bits of 'h' to within 0.25% bias." It also appears to work to |
140 |
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* use instead any of the variants proposed by David Stafford at |
141 |
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* http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html |
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* but these variants have not yet been tested as thoroughly |
143 |
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* in the context of the implementation of SplittableRandom. |
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* |
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* The mix32 function used for nextInt just consists of two of the |
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* five lines of mix64; avalanche testing shows that the 64-bit result |
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* has its top 32 bits avalanched well, though not the bottom 32 bits. |
148 |
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* DieHarder tests show that it is adequate for generating one |
149 |
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* random int from the 64-bit result of nextSeed. |
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* |
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* Support for the default (no-argument) constructor relies on an |
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* AtomicLong (defaultSeedGenerator) to help perform the |
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* equivalent of a split of a statically constructed |
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* SplittableRandom. Unlike other cases, this split must be |
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* performed in a thread-safe manner. We use |
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* AtomicLong.compareAndSet as the (typically) most efficient |
157 |
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* mechanism. To bootstrap, we start off using System.nanotime(), |
158 |
< |
* and update using another "genuinely random" constant |
159 |
< |
* DEFAULT_SEED_GAMMA. The default constructor uses GAMMA_GAMMA, |
160 |
< |
* not 0, for its splitSeed argument (addGammaModGeorge(0, |
161 |
< |
* GAMMA_GAMMA) == GAMMA_GAMMA) to reflect that each is split from |
162 |
< |
* this root generator, even though the root is not explicitly |
163 |
< |
* represented as a SplittableRandom. |
164 |
< |
*/ |
165 |
< |
|
166 |
< |
/** |
167 |
< |
* The "genuinely random" value for producing new gamma values. |
168 |
< |
* The value is arbitrary, subject to the requirement that it be |
169 |
< |
* greater or equal to 13. |
170 |
< |
*/ |
171 |
< |
private static final long GAMMA_GAMMA = 0xF2281E2DBA6606F3L; |
172 |
< |
|
173 |
< |
/** |
174 |
< |
* The "genuinely random" seed update value for default constructors. |
175 |
< |
* The value is arbitrary, subject to the requirement that it be |
176 |
< |
* greater or equal to 13. |
177 |
< |
*/ |
178 |
< |
private static final long DEFAULT_SEED_GAMMA = 0xBD24B73A95FB84D9L; |
154 |
> |
* File organization: First the non-public methods that constitute |
155 |
> |
* the main algorithm, then the main public methods, followed by |
156 |
> |
* some custom spliterator classes needed for stream methods. |
157 |
> |
*/ |
158 |
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|
159 |
|
/** |
160 |
< |
* The next seed for default constructors. |
160 |
> |
* The golden ratio scaled to 64bits, used as the initial gamma |
161 |
> |
* value for (unsplit) SplittableRandoms. |
162 |
|
*/ |
163 |
< |
private static final AtomicLong defaultSeedGenerator = |
184 |
< |
new AtomicLong(System.nanoTime()); |
163 |
> |
private static final long GOLDEN_GAMMA = 0x9e3779b97f4a7c15L; |
164 |
|
|
165 |
|
/** |
166 |
< |
* The seed, updated only via method nextSeed. |
166 |
> |
* The least non-zero value returned by nextDouble(). This value |
167 |
> |
* is scaled by a random value of 53 bits to produce a result. |
168 |
|
*/ |
169 |
< |
private long seed; |
169 |
> |
private static final double DOUBLE_ULP = 1.0 / (1L << 53); |
170 |
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|
171 |
|
/** |
172 |
< |
* The constant value added to seed (mod George) on each update. |
172 |
> |
* The seed. Updated only via method nextSeed. |
173 |
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*/ |
174 |
< |
private final long gamma; |
174 |
> |
private long seed; |
175 |
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|
176 |
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/** |
177 |
< |
* The next seed to use for splits. Propagated using |
198 |
< |
* addGammaModGeorge across instances. |
177 |
> |
* The step value. |
178 |
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*/ |
179 |
< |
private final long nextSplit; |
179 |
> |
private final long gamma; |
180 |
|
|
181 |
|
/** |
182 |
< |
* Internal constructor used by all other constructors and by |
204 |
< |
* method split. Establishes the initial seed for this instance, |
205 |
< |
* and uses the given splitSeed to establish gamma, as well as the |
206 |
< |
* nextSplit to use by this instance. |
182 |
> |
* Internal constructor used by all others except default constructor. |
183 |
|
*/ |
184 |
< |
private SplittableRandom(long seed, long splitSeed) { |
184 |
> |
private SplittableRandom(long seed, long gamma) { |
185 |
|
this.seed = seed; |
186 |
< |
long s = splitSeed, g; |
211 |
< |
do { // ensure gamma >= 13, considered as an unsigned integer |
212 |
< |
s = addGammaModGeorge(s, GAMMA_GAMMA); |
213 |
< |
g = mix64(s); |
214 |
< |
} while (Long.compareUnsigned(g, 13L) < 0); |
215 |
< |
this.gamma = g; |
216 |
< |
this.nextSplit = s; |
186 |
> |
this.gamma = gamma; |
187 |
|
} |
188 |
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|
189 |
|
/** |
190 |
< |
* Adds the given gamma value, g, to the given seed value s, mod |
191 |
< |
* George (2^64+13). We regard s and g as unsigned values |
192 |
< |
* (ranging from 0 to 2^64-1). We add g to s either once or twice |
193 |
< |
* (mod George) as necessary to produce an (unsigned) result less |
194 |
< |
* than 2^64. We require that g must be at least 13. This |
195 |
< |
* guarantees that if (s+g) mod George >= 2^64 then (s+g+g) mod |
226 |
< |
* George < 2^64; thus we need only a conditional, not a loop, |
227 |
< |
* to be sure of getting a representable value. |
228 |
< |
* |
229 |
< |
* @param s a seed value |
230 |
< |
* @param g a gamma value, 13 <= g (as unsigned) |
231 |
< |
*/ |
232 |
< |
private static long addGammaModGeorge(long s, long g) { |
233 |
< |
long p = s + g; |
234 |
< |
if (Long.compareUnsigned(p, g) >= 0) |
235 |
< |
return p; |
236 |
< |
long q = p - 13L; |
237 |
< |
return (Long.compareUnsigned(p, 13L) >= 0) ? q : (q + g); |
190 |
> |
* Computes Stafford variant 13 of 64bit mix function. |
191 |
> |
*/ |
192 |
> |
private static long mix64(long z) { |
193 |
> |
z *= 0xbf58476d1ce4e5b9L; |
194 |
> |
z = (z ^ (z >>> 32)) * 0x94d049bb133111ebL; |
195 |
> |
return z ^ (z >>> 32); |
196 |
|
} |
197 |
|
|
198 |
|
/** |
199 |
< |
* Updates in-place and returns seed. |
242 |
< |
* See above for explanation. |
199 |
> |
* Returns the 32 high bits of Stafford variant 4 mix64 function as int. |
200 |
|
*/ |
201 |
< |
private long nextSeed() { |
202 |
< |
return seed = addGammaModGeorge(seed, gamma); |
201 |
> |
private static int mix32(long z) { |
202 |
> |
z *= 0x62a9d9ed799705f5L; |
203 |
> |
return (int)(((z ^ (z >>> 28)) * 0xcb24d0a5c88c35b3L) >>> 32); |
204 |
|
} |
205 |
|
|
206 |
|
/** |
207 |
< |
* Returns a bit-mixed transformation of its argument. |
250 |
< |
* See above for explanation. |
207 |
> |
* Returns the gamma value to use for a new split instance. |
208 |
|
*/ |
209 |
< |
private static long mix64(long z) { |
210 |
< |
z ^= (z >>> 33); |
211 |
< |
z *= 0xff51afd7ed558ccdL; |
212 |
< |
z ^= (z >>> 33); |
213 |
< |
z *= 0xc4ceb9fe1a85ec53L; |
214 |
< |
z ^= (z >>> 33); |
258 |
< |
return z; |
209 |
> |
private static long mixGamma(long z) { |
210 |
> |
z *= 0xff51afd7ed558ccdL; // MurmurHash3 mix constants |
211 |
> |
z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L; |
212 |
> |
z = (z ^ (z >>> 33)) | 1L; // force to be odd |
213 |
> |
int n = Long.bitCount(z ^ (z >>> 1)); // ensure enough transitions |
214 |
> |
return (n < 24) ? z ^ 0xaaaaaaaaaaaaaaaaL : z; |
215 |
|
} |
216 |
|
|
217 |
|
/** |
218 |
< |
* Returns a bit-mixed int transformation of its argument. |
263 |
< |
* See above for explanation. |
218 |
> |
* Adds gamma to seed. |
219 |
|
*/ |
220 |
< |
private static int mix32(long z) { |
221 |
< |
z ^= (z >>> 33); |
267 |
< |
z *= 0xc4ceb9fe1a85ec53L; |
268 |
< |
return (int)(z >>> 32); |
220 |
> |
private long nextSeed() { |
221 |
> |
return seed += gamma; |
222 |
|
} |
223 |
|
|
224 |
|
/** |
225 |
< |
* Atomically updates and returns next seed for default constructor |
225 |
> |
* The seed generator for default constructors. |
226 |
|
*/ |
227 |
< |
private static long nextDefaultSeed() { |
228 |
< |
long oldSeed, newSeed; |
229 |
< |
do { |
230 |
< |
oldSeed = defaultSeedGenerator.get(); |
231 |
< |
newSeed = addGammaModGeorge(oldSeed, DEFAULT_SEED_GAMMA); |
232 |
< |
} while (!defaultSeedGenerator.compareAndSet(oldSeed, newSeed)); |
233 |
< |
return mix64(newSeed); |
227 |
> |
private static final AtomicLong defaultGen = new AtomicLong(initialSeed()); |
228 |
> |
|
229 |
> |
private static long initialSeed() { |
230 |
> |
String pp = java.security.AccessController.doPrivileged( |
231 |
> |
new sun.security.action.GetPropertyAction( |
232 |
> |
"java.util.secureRandomSeed")); |
233 |
> |
if (pp != null && pp.equalsIgnoreCase("true")) { |
234 |
> |
byte[] seedBytes = java.security.SecureRandom.getSeed(8); |
235 |
> |
long s = (long)(seedBytes[0]) & 0xffL; |
236 |
> |
for (int i = 1; i < 8; ++i) |
237 |
> |
s = (s << 8) | ((long)(seedBytes[i]) & 0xffL); |
238 |
> |
return s; |
239 |
> |
} |
240 |
> |
long h = 0L; |
241 |
> |
try { |
242 |
> |
Enumeration<NetworkInterface> ifcs = |
243 |
> |
NetworkInterface.getNetworkInterfaces(); |
244 |
> |
boolean retry = false; // retry once if getHardwareAddress is null |
245 |
> |
while (ifcs.hasMoreElements()) { |
246 |
> |
NetworkInterface ifc = ifcs.nextElement(); |
247 |
> |
if (!ifc.isVirtual()) { // skip fake addresses |
248 |
> |
byte[] bs = ifc.getHardwareAddress(); |
249 |
> |
if (bs != null) { |
250 |
> |
int n = bs.length; |
251 |
> |
int m = Math.min(n >>> 1, 4); |
252 |
> |
for (int i = 0; i < m; ++i) |
253 |
> |
h = (h << 16) ^ (bs[i] << 8) ^ bs[n-1-i]; |
254 |
> |
if (m < 4) |
255 |
> |
h = (h << 8) ^ bs[n-1-m]; |
256 |
> |
h = mix64(h); |
257 |
> |
break; |
258 |
> |
} |
259 |
> |
else if (!retry) |
260 |
> |
retry = true; |
261 |
> |
else |
262 |
> |
break; |
263 |
> |
} |
264 |
> |
} |
265 |
> |
} catch (Exception ignore) { |
266 |
> |
} |
267 |
> |
return (h ^ mix64(System.currentTimeMillis()) ^ |
268 |
> |
mix64(System.nanoTime())); |
269 |
|
} |
270 |
|
|
271 |
+ |
// IllegalArgumentException messages |
272 |
+ |
static final String BadBound = "bound must be positive"; |
273 |
+ |
static final String BadRange = "bound must be greater than origin"; |
274 |
+ |
static final String BadSize = "size must be non-negative"; |
275 |
+ |
|
276 |
|
/* |
277 |
|
* Internal versions of nextX methods used by streams, as well as |
278 |
|
* the public nextX(origin, bound) methods. These exist mainly to |
304 |
|
* evenly divisible by the range. The loop rejects candidates |
305 |
|
* computed from otherwise over-represented values. The |
306 |
|
* expected number of iterations under an ideal generator |
307 |
< |
* varies from 1 to 2, depending on the bound. |
307 |
> |
* varies from 1 to 2, depending on the bound. The loop itself |
308 |
> |
* takes an unlovable form. Because the first candidate is |
309 |
> |
* already available, we need a break-in-the-middle |
310 |
> |
* construction, which is concisely but cryptically performed |
311 |
> |
* within the while-condition of a body-less for loop. |
312 |
|
* |
313 |
|
* 4. Otherwise, the range cannot be represented as a positive |
314 |
< |
* long. Repeatedly generate unbounded longs until obtaining |
315 |
< |
* a candidate meeting constraints (with an expected number of |
316 |
< |
* iterations of less than two). |
314 |
> |
* long. The loop repeatedly generates unbounded longs until |
315 |
> |
* obtaining a candidate meeting constraints (with an expected |
316 |
> |
* number of iterations of less than two). |
317 |
|
*/ |
318 |
|
|
319 |
|
long r = mix64(nextSeed()); |
320 |
|
if (origin < bound) { |
321 |
|
long n = bound - origin, m = n - 1; |
322 |
< |
if ((n & m) == 0L) // power of two |
322 |
> |
if ((n & m) == 0L) // power of two |
323 |
|
r = (r & m) + origin; |
324 |
< |
else if (n > 0) { // reject over-represented candidates |
324 |
> |
else if (n > 0L) { // reject over-represented candidates |
325 |
|
for (long u = r >>> 1; // ensure nonnegative |
326 |
< |
u + m - (r = u % n) < 0L; // reject |
326 |
> |
u + m - (r = u % n) < 0L; // rejection check |
327 |
|
u = mix64(nextSeed()) >>> 1) // retry |
328 |
|
; |
329 |
|
r += origin; |
330 |
|
} |
331 |
< |
else { // range not representable as long |
331 |
> |
else { // range not representable as long |
332 |
|
while (r < origin || r >= bound) |
333 |
|
r = mix64(nextSeed()); |
334 |
|
} |
348 |
|
int r = mix32(nextSeed()); |
349 |
|
if (origin < bound) { |
350 |
|
int n = bound - origin, m = n - 1; |
351 |
< |
if ((n & m) == 0L) |
351 |
> |
if ((n & m) == 0) |
352 |
|
r = (r & m) + origin; |
353 |
|
else if (n > 0) { |
354 |
|
for (int u = r >>> 1; |
355 |
< |
u + m - (r = u % n) < 0L; |
355 |
> |
u + m - (r = u % n) < 0; |
356 |
|
u = mix32(nextSeed()) >>> 1) |
357 |
|
; |
358 |
|
r += origin; |
373 |
|
* @return a pseudorandom value |
374 |
|
*/ |
375 |
|
final double internalNextDouble(double origin, double bound) { |
376 |
< |
long bits = (1023L << 52) | (nextLong() >>> 12); |
380 |
< |
double r = Double.longBitsToDouble(bits) - 1.0; |
376 |
> |
double r = (nextLong() >>> 11) * DOUBLE_ULP; |
377 |
|
if (origin < bound) { |
378 |
|
r = r * (bound - origin) + origin; |
379 |
< |
if (r == bound) // correct for rounding |
379 |
> |
if (r >= bound) // correct for rounding |
380 |
|
r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
381 |
|
} |
382 |
|
return r; |
385 |
|
/* ---------------- public methods ---------------- */ |
386 |
|
|
387 |
|
/** |
388 |
< |
* Creates a new SplittableRandom instance using the given initial |
389 |
< |
* seed. Two SplittableRandom instances created with the same seed |
390 |
< |
* generate identical sequences of values. |
388 |
> |
* Creates a new SplittableRandom instance using the specified |
389 |
> |
* initial seed. SplittableRandom instances created with the same |
390 |
> |
* seed in the same program generate identical sequences of values. |
391 |
|
* |
392 |
|
* @param seed the initial seed |
393 |
|
*/ |
394 |
|
public SplittableRandom(long seed) { |
395 |
< |
this(seed, 0); |
395 |
> |
this(seed, GOLDEN_GAMMA); |
396 |
|
} |
397 |
|
|
398 |
|
/** |
401 |
|
* of those of any other instances in the current program; and |
402 |
|
* may, and typically does, vary across program invocations. |
403 |
|
*/ |
404 |
< |
public SplittableRandom() { |
405 |
< |
this(nextDefaultSeed(), GAMMA_GAMMA); |
404 |
> |
public SplittableRandom() { // emulate defaultGen.split() |
405 |
> |
long s = defaultGen.getAndAdd(2 * GOLDEN_GAMMA); |
406 |
> |
this.seed = mix64(s); |
407 |
> |
this.gamma = mixGamma(s + GOLDEN_GAMMA); |
408 |
|
} |
409 |
|
|
410 |
|
/** |
422 |
|
* @return the new SplittableRandom instance |
423 |
|
*/ |
424 |
|
public SplittableRandom split() { |
425 |
< |
return new SplittableRandom(nextSeed(), nextSplit); |
425 |
> |
return new SplittableRandom(nextLong(), mixGamma(nextSeed())); |
426 |
|
} |
427 |
|
|
428 |
|
/** |
429 |
|
* Returns a pseudorandom {@code int} value. |
430 |
|
* |
431 |
< |
* @return a pseudorandom value |
431 |
> |
* @return a pseudorandom {@code int} value |
432 |
|
*/ |
433 |
|
public int nextInt() { |
434 |
|
return mix32(nextSeed()); |
435 |
|
} |
436 |
|
|
437 |
|
/** |
438 |
< |
* Returns a pseudorandom {@code int} value between 0 (inclusive) |
438 |
> |
* Returns a pseudorandom {@code int} value between zero (inclusive) |
439 |
|
* and the specified bound (exclusive). |
440 |
|
* |
441 |
< |
* @param bound the bound on the random number to be returned. Must be |
442 |
< |
* positive. |
443 |
< |
* @return a pseudorandom {@code int} value between {@code 0} |
444 |
< |
* (inclusive) and the bound (exclusive). |
447 |
< |
* @exception IllegalArgumentException if the bound is not positive |
441 |
> |
* @param bound the upper bound (exclusive). Must be positive. |
442 |
> |
* @return a pseudorandom {@code int} value between zero |
443 |
> |
* (inclusive) and the bound (exclusive) |
444 |
> |
* @throws IllegalArgumentException if {@code bound} is not positive |
445 |
|
*/ |
446 |
|
public int nextInt(int bound) { |
447 |
|
if (bound <= 0) |
448 |
< |
throw new IllegalArgumentException("bound must be positive"); |
448 |
> |
throw new IllegalArgumentException(BadBound); |
449 |
|
// Specialize internalNextInt for origin 0 |
450 |
|
int r = mix32(nextSeed()); |
451 |
|
int m = bound - 1; |
452 |
< |
if ((bound & m) == 0L) // power of two |
452 |
> |
if ((bound & m) == 0) // power of two |
453 |
|
r &= m; |
454 |
|
else { // reject over-represented candidates |
455 |
|
for (int u = r >>> 1; |
456 |
< |
u + m - (r = u % bound) < 0L; |
456 |
> |
u + m - (r = u % bound) < 0; |
457 |
|
u = mix32(nextSeed()) >>> 1) |
458 |
|
; |
459 |
|
} |
467 |
|
* @param origin the least value returned |
468 |
|
* @param bound the upper bound (exclusive) |
469 |
|
* @return a pseudorandom {@code int} value between the origin |
470 |
< |
* (inclusive) and the bound (exclusive). |
471 |
< |
* @exception IllegalArgumentException if {@code origin} is greater than |
470 |
> |
* (inclusive) and the bound (exclusive) |
471 |
> |
* @throws IllegalArgumentException if {@code origin} is greater than |
472 |
|
* or equal to {@code bound} |
473 |
|
*/ |
474 |
|
public int nextInt(int origin, int bound) { |
475 |
|
if (origin >= bound) |
476 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
476 |
> |
throw new IllegalArgumentException(BadRange); |
477 |
|
return internalNextInt(origin, bound); |
478 |
|
} |
479 |
|
|
480 |
|
/** |
481 |
|
* Returns a pseudorandom {@code long} value. |
482 |
|
* |
483 |
< |
* @return a pseudorandom value |
483 |
> |
* @return a pseudorandom {@code long} value |
484 |
|
*/ |
485 |
|
public long nextLong() { |
486 |
|
return mix64(nextSeed()); |
487 |
|
} |
488 |
|
|
489 |
|
/** |
490 |
< |
* Returns a pseudorandom {@code long} value between 0 (inclusive) |
490 |
> |
* Returns a pseudorandom {@code long} value between zero (inclusive) |
491 |
|
* and the specified bound (exclusive). |
492 |
|
* |
493 |
< |
* @param bound the bound on the random number to be returned. Must be |
494 |
< |
* positive. |
495 |
< |
* @return a pseudorandom {@code long} value between {@code 0} |
496 |
< |
* (inclusive) and the bound (exclusive). |
500 |
< |
* @exception IllegalArgumentException if the bound is not positive |
493 |
> |
* @param bound the upper bound (exclusive). Must be positive. |
494 |
> |
* @return a pseudorandom {@code long} value between zero |
495 |
> |
* (inclusive) and the bound (exclusive) |
496 |
> |
* @throws IllegalArgumentException if {@code bound} is not positive |
497 |
|
*/ |
498 |
|
public long nextLong(long bound) { |
499 |
|
if (bound <= 0) |
500 |
< |
throw new IllegalArgumentException("bound must be positive"); |
500 |
> |
throw new IllegalArgumentException(BadBound); |
501 |
|
// Specialize internalNextLong for origin 0 |
502 |
|
long r = mix64(nextSeed()); |
503 |
|
long m = bound - 1; |
519 |
|
* @param origin the least value returned |
520 |
|
* @param bound the upper bound (exclusive) |
521 |
|
* @return a pseudorandom {@code long} value between the origin |
522 |
< |
* (inclusive) and the bound (exclusive). |
523 |
< |
* @exception IllegalArgumentException if {@code origin} is greater than |
522 |
> |
* (inclusive) and the bound (exclusive) |
523 |
> |
* @throws IllegalArgumentException if {@code origin} is greater than |
524 |
|
* or equal to {@code bound} |
525 |
|
*/ |
526 |
|
public long nextLong(long origin, long bound) { |
527 |
|
if (origin >= bound) |
528 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
528 |
> |
throw new IllegalArgumentException(BadRange); |
529 |
|
return internalNextLong(origin, bound); |
530 |
|
} |
531 |
|
|
532 |
|
/** |
533 |
< |
* Returns a pseudorandom {@code double} value between {@code 0.0} |
534 |
< |
* (inclusive) and {@code 1.0} (exclusive). |
533 |
> |
* Returns a pseudorandom {@code double} value between zero |
534 |
> |
* (inclusive) and one (exclusive). |
535 |
|
* |
536 |
< |
* @return a pseudorandom value between {@code 0.0} |
537 |
< |
* (inclusive) and {@code 1.0} (exclusive) |
536 |
> |
* @return a pseudorandom {@code double} value between zero |
537 |
> |
* (inclusive) and one (exclusive) |
538 |
|
*/ |
539 |
|
public double nextDouble() { |
540 |
< |
long bits = (1023L << 52) | (nextLong() >>> 12); |
545 |
< |
return Double.longBitsToDouble(bits) - 1.0; |
540 |
> |
return (mix64(nextSeed()) >>> 11) * DOUBLE_ULP; |
541 |
|
} |
542 |
|
|
543 |
|
/** |
544 |
|
* Returns a pseudorandom {@code double} value between 0.0 |
545 |
|
* (inclusive) and the specified bound (exclusive). |
546 |
|
* |
547 |
< |
* @param bound the bound on the random number to be returned. Must be |
548 |
< |
* positive. |
549 |
< |
* @return a pseudorandom {@code double} value between {@code 0.0} |
555 |
< |
* (inclusive) and the bound (exclusive). |
547 |
> |
* @param bound the upper bound (exclusive). Must be positive. |
548 |
> |
* @return a pseudorandom {@code double} value between zero |
549 |
> |
* (inclusive) and the bound (exclusive) |
550 |
|
* @throws IllegalArgumentException if {@code bound} is not positive |
551 |
|
*/ |
552 |
|
public double nextDouble(double bound) { |
553 |
< |
if (bound <= 0.0) |
554 |
< |
throw new IllegalArgumentException("bound must be positive"); |
555 |
< |
double result = nextDouble() * bound; |
553 |
> |
if (!(bound > 0.0)) |
554 |
> |
throw new IllegalArgumentException(BadBound); |
555 |
> |
double result = (mix64(nextSeed()) >>> 11) * DOUBLE_ULP * bound; |
556 |
|
return (result < bound) ? result : // correct for rounding |
557 |
|
Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
558 |
|
} |
559 |
|
|
560 |
|
/** |
561 |
< |
* Returns a pseudorandom {@code double} value between the given |
561 |
> |
* Returns a pseudorandom {@code double} value between the specified |
562 |
|
* origin (inclusive) and bound (exclusive). |
563 |
|
* |
564 |
|
* @param origin the least value returned |
565 |
< |
* @param bound the upper bound |
565 |
> |
* @param bound the upper bound (exclusive) |
566 |
|
* @return a pseudorandom {@code double} value between the origin |
567 |
< |
* (inclusive) and the bound (exclusive). |
567 |
> |
* (inclusive) and the bound (exclusive) |
568 |
|
* @throws IllegalArgumentException if {@code origin} is greater than |
569 |
|
* or equal to {@code bound} |
570 |
|
*/ |
571 |
|
public double nextDouble(double origin, double bound) { |
572 |
< |
if (origin >= bound) |
573 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
572 |
> |
if (!(origin < bound)) |
573 |
> |
throw new IllegalArgumentException(BadRange); |
574 |
|
return internalNextDouble(origin, bound); |
575 |
|
} |
576 |
|
|
577 |
+ |
/** |
578 |
+ |
* Returns a pseudorandom {@code boolean} value. |
579 |
+ |
* |
580 |
+ |
* @return a pseudorandom {@code boolean} value |
581 |
+ |
*/ |
582 |
+ |
public boolean nextBoolean() { |
583 |
+ |
return mix32(nextSeed()) < 0; |
584 |
+ |
} |
585 |
+ |
|
586 |
|
// stream methods, coded in a way intended to better isolate for |
587 |
|
// maintenance purposes the small differences across forms. |
588 |
|
|
589 |
|
/** |
590 |
< |
* Returns a stream with the given {@code streamSize} number of |
591 |
< |
* pseudorandom {@code int} values. |
590 |
> |
* Returns a stream producing the given {@code streamSize} number |
591 |
> |
* of pseudorandom {@code int} values from this generator and/or |
592 |
> |
* one split from it. |
593 |
|
* |
594 |
|
* @param streamSize the number of values to generate |
595 |
|
* @return a stream of pseudorandom {@code int} values |
596 |
|
* @throws IllegalArgumentException if {@code streamSize} is |
597 |
< |
* less than zero |
597 |
> |
* less than zero |
598 |
|
*/ |
599 |
|
public IntStream ints(long streamSize) { |
600 |
|
if (streamSize < 0L) |
601 |
< |
throw new IllegalArgumentException("negative Stream size"); |
601 |
> |
throw new IllegalArgumentException(BadSize); |
602 |
|
return StreamSupport.intStream |
603 |
|
(new RandomIntsSpliterator |
604 |
|
(this, 0L, streamSize, Integer.MAX_VALUE, 0), |
607 |
|
|
608 |
|
/** |
609 |
|
* Returns an effectively unlimited stream of pseudorandom {@code int} |
610 |
< |
* values |
610 |
> |
* values from this generator and/or one split from it. |
611 |
|
* |
612 |
|
* @implNote This method is implemented to be equivalent to {@code |
613 |
|
* ints(Long.MAX_VALUE)}. |
622 |
|
} |
623 |
|
|
624 |
|
/** |
625 |
< |
* Returns a stream with the given {@code streamSize} number of |
626 |
< |
* pseudorandom {@code int} values, each conforming to the given |
627 |
< |
* origin and bound. |
625 |
> |
* Returns a stream producing the given {@code streamSize} number |
626 |
> |
* of pseudorandom {@code int} values from this generator and/or one split |
627 |
> |
* from it; each value conforms to the given origin (inclusive) and bound |
628 |
> |
* (exclusive). |
629 |
|
* |
630 |
|
* @param streamSize the number of values to generate |
631 |
< |
* @param randomNumberOrigin the origin of each random value |
632 |
< |
* @param randomNumberBound the bound of each random value |
631 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
632 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
633 |
|
* @return a stream of pseudorandom {@code int} values, |
634 |
< |
* each with the given origin and bound. |
634 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
635 |
|
* @throws IllegalArgumentException if {@code streamSize} is |
636 |
< |
* less than zero. |
632 |
< |
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
636 |
> |
* less than zero, or {@code randomNumberOrigin} |
637 |
|
* is greater than or equal to {@code randomNumberBound} |
638 |
|
*/ |
639 |
|
public IntStream ints(long streamSize, int randomNumberOrigin, |
640 |
|
int randomNumberBound) { |
641 |
|
if (streamSize < 0L) |
642 |
< |
throw new IllegalArgumentException("negative Stream size"); |
642 |
> |
throw new IllegalArgumentException(BadSize); |
643 |
|
if (randomNumberOrigin >= randomNumberBound) |
644 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
644 |
> |
throw new IllegalArgumentException(BadRange); |
645 |
|
return StreamSupport.intStream |
646 |
|
(new RandomIntsSpliterator |
647 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
650 |
|
|
651 |
|
/** |
652 |
|
* Returns an effectively unlimited stream of pseudorandom {@code |
653 |
< |
* int} values, each conforming to the given origin and bound. |
653 |
> |
* int} values from this generator and/or one split from it; each value |
654 |
> |
* conforms to the given origin (inclusive) and bound (exclusive). |
655 |
|
* |
656 |
|
* @implNote This method is implemented to be equivalent to {@code |
657 |
|
* ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
658 |
|
* |
659 |
< |
* @param randomNumberOrigin the origin of each random value |
660 |
< |
* @param randomNumberBound the bound of each random value |
659 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
660 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
661 |
|
* @return a stream of pseudorandom {@code int} values, |
662 |
< |
* each with the given origin and bound. |
662 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
663 |
|
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
664 |
|
* is greater than or equal to {@code randomNumberBound} |
665 |
|
*/ |
666 |
|
public IntStream ints(int randomNumberOrigin, int randomNumberBound) { |
667 |
|
if (randomNumberOrigin >= randomNumberBound) |
668 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
668 |
> |
throw new IllegalArgumentException(BadRange); |
669 |
|
return StreamSupport.intStream |
670 |
|
(new RandomIntsSpliterator |
671 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
673 |
|
} |
674 |
|
|
675 |
|
/** |
676 |
< |
* Returns a stream with the given {@code streamSize} number of |
677 |
< |
* pseudorandom {@code long} values. |
676 |
> |
* Returns a stream producing the given {@code streamSize} number |
677 |
> |
* of pseudorandom {@code long} values from this generator and/or |
678 |
> |
* one split from it. |
679 |
|
* |
680 |
|
* @param streamSize the number of values to generate |
681 |
< |
* @return a stream of {@code long} values |
681 |
> |
* @return a stream of pseudorandom {@code long} values |
682 |
|
* @throws IllegalArgumentException if {@code streamSize} is |
683 |
< |
* less than zero |
683 |
> |
* less than zero |
684 |
|
*/ |
685 |
|
public LongStream longs(long streamSize) { |
686 |
|
if (streamSize < 0L) |
687 |
< |
throw new IllegalArgumentException("negative Stream size"); |
687 |
> |
throw new IllegalArgumentException(BadSize); |
688 |
|
return StreamSupport.longStream |
689 |
|
(new RandomLongsSpliterator |
690 |
|
(this, 0L, streamSize, Long.MAX_VALUE, 0L), |
692 |
|
} |
693 |
|
|
694 |
|
/** |
695 |
< |
* Returns an effectively unlimited stream of pseudorandom {@code long} |
696 |
< |
* values. |
695 |
> |
* Returns an effectively unlimited stream of pseudorandom {@code |
696 |
> |
* long} values from this generator and/or one split from it. |
697 |
|
* |
698 |
|
* @implNote This method is implemented to be equivalent to {@code |
699 |
|
* longs(Long.MAX_VALUE)}. |
708 |
|
} |
709 |
|
|
710 |
|
/** |
711 |
< |
* Returns a stream with the given {@code streamSize} number of |
712 |
< |
* pseudorandom {@code long} values, each conforming to the |
713 |
< |
* given origin and bound. |
711 |
> |
* Returns a stream producing the given {@code streamSize} number of |
712 |
> |
* pseudorandom {@code long} values from this generator and/or one split |
713 |
> |
* from it; each value conforms to the given origin (inclusive) and bound |
714 |
> |
* (exclusive). |
715 |
|
* |
716 |
|
* @param streamSize the number of values to generate |
717 |
< |
* @param randomNumberOrigin the origin of each random value |
718 |
< |
* @param randomNumberBound the bound of each random value |
717 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
718 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
719 |
|
* @return a stream of pseudorandom {@code long} values, |
720 |
< |
* each with the given origin and bound. |
720 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
721 |
|
* @throws IllegalArgumentException if {@code streamSize} is |
722 |
< |
* less than zero. |
716 |
< |
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
722 |
> |
* less than zero, or {@code randomNumberOrigin} |
723 |
|
* is greater than or equal to {@code randomNumberBound} |
724 |
|
*/ |
725 |
|
public LongStream longs(long streamSize, long randomNumberOrigin, |
726 |
|
long randomNumberBound) { |
727 |
|
if (streamSize < 0L) |
728 |
< |
throw new IllegalArgumentException("negative Stream size"); |
728 |
> |
throw new IllegalArgumentException(BadSize); |
729 |
|
if (randomNumberOrigin >= randomNumberBound) |
730 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
730 |
> |
throw new IllegalArgumentException(BadRange); |
731 |
|
return StreamSupport.longStream |
732 |
|
(new RandomLongsSpliterator |
733 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
736 |
|
|
737 |
|
/** |
738 |
|
* Returns an effectively unlimited stream of pseudorandom {@code |
739 |
< |
* long} values, each conforming to the given origin and bound. |
739 |
> |
* long} values from this generator and/or one split from it; each value |
740 |
> |
* conforms to the given origin (inclusive) and bound (exclusive). |
741 |
|
* |
742 |
|
* @implNote This method is implemented to be equivalent to {@code |
743 |
|
* longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
744 |
|
* |
745 |
< |
* @param randomNumberOrigin the origin of each random value |
746 |
< |
* @param randomNumberBound the bound of each random value |
745 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
746 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
747 |
|
* @return a stream of pseudorandom {@code long} values, |
748 |
< |
* each with the given origin and bound. |
748 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
749 |
|
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
750 |
|
* is greater than or equal to {@code randomNumberBound} |
751 |
|
*/ |
752 |
|
public LongStream longs(long randomNumberOrigin, long randomNumberBound) { |
753 |
|
if (randomNumberOrigin >= randomNumberBound) |
754 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
754 |
> |
throw new IllegalArgumentException(BadRange); |
755 |
|
return StreamSupport.longStream |
756 |
|
(new RandomLongsSpliterator |
757 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
759 |
|
} |
760 |
|
|
761 |
|
/** |
762 |
< |
* Returns a stream with the given {@code streamSize} number of |
763 |
< |
* pseudorandom {@code double} values, each between {@code 0.0} |
764 |
< |
* (inclusive) and {@code 1.0} (exclusive). |
762 |
> |
* Returns a stream producing the given {@code streamSize} number of |
763 |
> |
* pseudorandom {@code double} values from this generator and/or one split |
764 |
> |
* from it; each value is between zero (inclusive) and one (exclusive). |
765 |
|
* |
766 |
|
* @param streamSize the number of values to generate |
767 |
|
* @return a stream of {@code double} values |
768 |
|
* @throws IllegalArgumentException if {@code streamSize} is |
769 |
< |
* less than zero |
769 |
> |
* less than zero |
770 |
|
*/ |
771 |
|
public DoubleStream doubles(long streamSize) { |
772 |
|
if (streamSize < 0L) |
773 |
< |
throw new IllegalArgumentException("negative Stream size"); |
773 |
> |
throw new IllegalArgumentException(BadSize); |
774 |
|
return StreamSupport.doubleStream |
775 |
|
(new RandomDoublesSpliterator |
776 |
|
(this, 0L, streamSize, Double.MAX_VALUE, 0.0), |
779 |
|
|
780 |
|
/** |
781 |
|
* Returns an effectively unlimited stream of pseudorandom {@code |
782 |
< |
* double} values, each between {@code 0.0} (inclusive) and {@code |
783 |
< |
* 1.0} (exclusive). |
782 |
> |
* double} values from this generator and/or one split from it; each value |
783 |
> |
* is between zero (inclusive) and one (exclusive). |
784 |
|
* |
785 |
|
* @implNote This method is implemented to be equivalent to {@code |
786 |
|
* doubles(Long.MAX_VALUE)}. |
795 |
|
} |
796 |
|
|
797 |
|
/** |
798 |
< |
* Returns a stream with the given {@code streamSize} number of |
799 |
< |
* pseudorandom {@code double} values, each conforming to the |
800 |
< |
* given origin and bound. |
798 |
> |
* Returns a stream producing the given {@code streamSize} number of |
799 |
> |
* pseudorandom {@code double} values from this generator and/or one split |
800 |
> |
* from it; each value conforms to the given origin (inclusive) and bound |
801 |
> |
* (exclusive). |
802 |
|
* |
803 |
|
* @param streamSize the number of values to generate |
804 |
< |
* @param randomNumberOrigin the origin of each random value |
805 |
< |
* @param randomNumberBound the bound of each random value |
804 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
805 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
806 |
|
* @return a stream of pseudorandom {@code double} values, |
807 |
< |
* each with the given origin and bound. |
807 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
808 |
|
* @throws IllegalArgumentException if {@code streamSize} is |
809 |
< |
* less than zero. |
809 |
> |
* less than zero |
810 |
|
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
811 |
|
* is greater than or equal to {@code randomNumberBound} |
812 |
|
*/ |
813 |
|
public DoubleStream doubles(long streamSize, double randomNumberOrigin, |
814 |
|
double randomNumberBound) { |
815 |
|
if (streamSize < 0L) |
816 |
< |
throw new IllegalArgumentException("negative Stream size"); |
817 |
< |
if (randomNumberOrigin >= randomNumberBound) |
818 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
816 |
> |
throw new IllegalArgumentException(BadSize); |
817 |
> |
if (!(randomNumberOrigin < randomNumberBound)) |
818 |
> |
throw new IllegalArgumentException(BadRange); |
819 |
|
return StreamSupport.doubleStream |
820 |
|
(new RandomDoublesSpliterator |
821 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
824 |
|
|
825 |
|
/** |
826 |
|
* Returns an effectively unlimited stream of pseudorandom {@code |
827 |
< |
* double} values, each conforming to the given origin and bound. |
827 |
> |
* double} values from this generator and/or one split from it; each value |
828 |
> |
* conforms to the given origin (inclusive) and bound (exclusive). |
829 |
|
* |
830 |
|
* @implNote This method is implemented to be equivalent to {@code |
831 |
|
* doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
832 |
|
* |
833 |
< |
* @param randomNumberOrigin the origin of each random value |
834 |
< |
* @param randomNumberBound the bound of each random value |
833 |
> |
* @param randomNumberOrigin the origin (inclusive) of each random value |
834 |
> |
* @param randomNumberBound the bound (exclusive) of each random value |
835 |
|
* @return a stream of pseudorandom {@code double} values, |
836 |
< |
* each with the given origin and bound. |
836 |
> |
* each with the given origin (inclusive) and bound (exclusive) |
837 |
|
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
838 |
|
* is greater than or equal to {@code randomNumberBound} |
839 |
|
*/ |
840 |
|
public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) { |
841 |
< |
if (randomNumberOrigin >= randomNumberBound) |
842 |
< |
throw new IllegalArgumentException("bound must be greater than origin"); |
841 |
> |
if (!(randomNumberOrigin < randomNumberBound)) |
842 |
> |
throw new IllegalArgumentException(BadRange); |
843 |
|
return StreamSupport.doubleStream |
844 |
|
(new RandomDoublesSpliterator |
845 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
848 |
|
|
849 |
|
/** |
850 |
|
* Spliterator for int streams. We multiplex the four int |
851 |
< |
* versions into one class by treating and bound < origin as |
851 |
> |
* versions into one class by treating a bound less than origin as |
852 |
|
* unbounded, and also by treating "infinite" as equivalent to |
853 |
|
* Long.MAX_VALUE. For splits, it uses the standard divide-by-two |
854 |
|
* approach. The long and double versions of this class are |
855 |
|
* identical except for types. |
856 |
|
*/ |
857 |
< |
static class RandomIntsSpliterator implements Spliterator.OfInt { |
857 |
> |
static final class RandomIntsSpliterator implements Spliterator.OfInt { |
858 |
|
final SplittableRandom rng; |
859 |
|
long index; |
860 |
|
final long fence; |
878 |
|
|
879 |
|
public int characteristics() { |
880 |
|
return (Spliterator.SIZED | Spliterator.SUBSIZED | |
881 |
< |
Spliterator.ORDERED | Spliterator.NONNULL | |
873 |
< |
Spliterator.IMMUTABLE); |
881 |
> |
Spliterator.NONNULL | Spliterator.IMMUTABLE); |
882 |
|
} |
883 |
|
|
884 |
|
public boolean tryAdvance(IntConsumer consumer) { |
897 |
|
long i = index, f = fence; |
898 |
|
if (i < f) { |
899 |
|
index = f; |
900 |
+ |
SplittableRandom r = rng; |
901 |
|
int o = origin, b = bound; |
902 |
|
do { |
903 |
< |
consumer.accept(rng.internalNextInt(o, b)); |
903 |
> |
consumer.accept(r.internalNextInt(o, b)); |
904 |
|
} while (++i < f); |
905 |
|
} |
906 |
|
} |
909 |
|
/** |
910 |
|
* Spliterator for long streams. |
911 |
|
*/ |
912 |
< |
static class RandomLongsSpliterator implements Spliterator.OfLong { |
912 |
> |
static final class RandomLongsSpliterator implements Spliterator.OfLong { |
913 |
|
final SplittableRandom rng; |
914 |
|
long index; |
915 |
|
final long fence; |
933 |
|
|
934 |
|
public int characteristics() { |
935 |
|
return (Spliterator.SIZED | Spliterator.SUBSIZED | |
936 |
< |
Spliterator.ORDERED | Spliterator.NONNULL | |
928 |
< |
Spliterator.IMMUTABLE); |
936 |
> |
Spliterator.NONNULL | Spliterator.IMMUTABLE); |
937 |
|
} |
938 |
|
|
939 |
|
public boolean tryAdvance(LongConsumer consumer) { |
952 |
|
long i = index, f = fence; |
953 |
|
if (i < f) { |
954 |
|
index = f; |
955 |
+ |
SplittableRandom r = rng; |
956 |
|
long o = origin, b = bound; |
957 |
|
do { |
958 |
< |
consumer.accept(rng.internalNextLong(o, b)); |
958 |
> |
consumer.accept(r.internalNextLong(o, b)); |
959 |
|
} while (++i < f); |
960 |
|
} |
961 |
|
} |
965 |
|
/** |
966 |
|
* Spliterator for double streams. |
967 |
|
*/ |
968 |
< |
static class RandomDoublesSpliterator implements Spliterator.OfDouble { |
968 |
> |
static final class RandomDoublesSpliterator implements Spliterator.OfDouble { |
969 |
|
final SplittableRandom rng; |
970 |
|
long index; |
971 |
|
final long fence; |
989 |
|
|
990 |
|
public int characteristics() { |
991 |
|
return (Spliterator.SIZED | Spliterator.SUBSIZED | |
992 |
< |
Spliterator.ORDERED | Spliterator.NONNULL | |
984 |
< |
Spliterator.IMMUTABLE); |
992 |
> |
Spliterator.NONNULL | Spliterator.IMMUTABLE); |
993 |
|
} |
994 |
|
|
995 |
|
public boolean tryAdvance(DoubleConsumer consumer) { |
1008 |
|
long i = index, f = fence; |
1009 |
|
if (i < f) { |
1010 |
|
index = f; |
1011 |
+ |
SplittableRandom r = rng; |
1012 |
|
double o = origin, b = bound; |
1013 |
|
do { |
1014 |
< |
consumer.accept(rng.internalNextDouble(o, b)); |
1014 |
> |
consumer.accept(r.internalNextDouble(o, b)); |
1015 |
|
} while (++i < f); |
1016 |
|
} |
1017 |
|
} |
1018 |
|
} |
1019 |
|
|
1020 |
|
} |
1012 |
– |
|