992 lines
38 KiB
992 lines
38 KiB
/*
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* Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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package java.util;
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import java.util.concurrent.atomic.AtomicLong;
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import java.util.function.IntConsumer;
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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.StreamSupport;
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import java.util.stream.IntStream;
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import java.util.stream.LongStream;
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import java.util.stream.DoubleStream;
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/**
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* A generator of uniform pseudorandom values applicable for use in
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* (among other contexts) isolated parallel computations that may
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* generate subtasks. Class {@code SplittableRandom} supports methods for
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* producing pseudorandom numbers of type {@code int}, {@code long},
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* and {@code double} with similar usages as for class
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* {@link java.util.Random} but differs in the following ways:
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*
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* <ul>
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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.
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* (Most recently validated with <a
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* href="http://www.phy.duke.edu/~rgb/General/dieharder.php"> version
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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
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* least approximately, for others as well. The <em>period</em>
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* (length of any series of generated values before it repeats) is at
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* least 2<sup>64</sup>. </li>
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*
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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
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* 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
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* generated by a single thread using a single {@code
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* SplittableRandom} object. </li>
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*
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* <li>Instances of SplittableRandom are <em>not</em> thread-safe.
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* They are designed to be split, not shared, across threads. For
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* example, a {@link java.util.concurrent.ForkJoinTask
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* fork/join-style} computation using random numbers might include a
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* construction of the form {@code new
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* Subtask(aSplittableRandom.split()).fork()}.
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*
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* <li>This class provides additional methods for generating random
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* streams, that employ the above techniques when used in {@code
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* stream.parallel()} mode.</li>
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*
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* </ul>
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*
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* <p>Instances of {@code SplittableRandom} are not cryptographically
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* secure. Consider instead using {@link java.security.SecureRandom}
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* in security-sensitive applications. Additionally,
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* default-constructed instances do not use a cryptographically random
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* seed unless the {@linkplain System#getProperty system property}
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* {@code java.util.secureRandomSeed} is set to {@code true}.
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*
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* @author Guy Steele
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* @author Doug Lea
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* @since 1.8
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*/
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public final class SplittableRandom {
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/*
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* Implementation Overview.
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*
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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, as well as those in "Parallel random numbers: as
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* easy as 1, 2, 3" by Salmon, Morae, Dror, and Shaw, SC 2011. It
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* differs mainly in simplifying and cheapening operations.
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*
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* The primary update step (method nextSeed()) is to add a
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* constant ("gamma") to the current (64 bit) seed, forming a
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* simple sequence. The seed and the gamma values for any two
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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
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* (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html)
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* "Mix13" variant of the "64-bit finalizer" function in Austin
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* Appleby's MurmurHash3 algorithm (see
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* http://code.google.com/p/smhasher/wiki/MurmurHash3). The mix32
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* function is based on Stafford's Mix04 mix function, but returns
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* the upper 32 bits cast as int.
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*
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* The split operation uses the current generator to form the seed
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* and gamma for another SplittableRandom. To conservatively
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* avoid potential correlations between seed and value generation,
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* gamma selection (method mixGamma) uses different
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* (Murmurhash3's) mix constants. To avoid potential weaknesses
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* in bit-mixing transformations, we restrict gammas to odd values
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* with at least 24 0-1 or 1-0 bit transitions. Rather than
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* rejecting candidates with too few or too many bits set, method
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* mixGamma flips some bits (which has the effect of mapping at
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* most 4 to any given gamma value). This reduces the effective
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* set of 64bit odd gamma values by about 2%, and serves as an
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* automated screening for sequence constant selection that is
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* left as an empirical decision in some other hashing and crypto
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* algorithms.
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*
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* The resulting generator thus transforms a sequence in which
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* (typically) many bits change on each step, with an inexpensive
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* mixer with good (but less than cryptographically secure)
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* avalanching.
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*
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* The default (no-argument) constructor, in essence, invokes
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* split() for a common "defaultGen" SplittableRandom. Unlike
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* other cases, this split must be performed in a thread-safe
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* manner, so we use an AtomicLong to represent the seed rather
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* than use an explicit SplittableRandom. To bootstrap the
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* defaultGen, we start off using a seed based on current time
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* unless the java.util.secureRandomSeed property is set. This
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* serves as a slimmed-down (and insecure) variant of SecureRandom
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* that also avoids stalls that may occur when using /dev/random.
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*
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* It is a relatively simple matter to apply the basic design here
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* to use 128 bit seeds. However, emulating 128bit arithmetic and
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* carrying around twice the state add more overhead than appears
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* warranted for current usages.
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*
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* File organization: First the non-public methods that constitute
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* the main algorithm, then the main public methods, followed by
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* some custom spliterator classes needed for stream methods.
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*/
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/**
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* The golden ratio scaled to 64bits, used as the initial gamma
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* value for (unsplit) SplittableRandoms.
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*/
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private static final long GOLDEN_GAMMA = 0x9e3779b97f4a7c15L;
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/**
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* The least non-zero value returned by nextDouble(). This value
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* is scaled by a random value of 53 bits to produce a result.
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*/
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private static final double DOUBLE_UNIT = 0x1.0p-53; // 1.0 / (1L << 53);
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/**
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* The seed. Updated only via method nextSeed.
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*/
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private long seed;
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/**
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* The step value.
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*/
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private final long gamma;
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/**
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* Internal constructor used by all others except default constructor.
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*/
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private SplittableRandom(long seed, long gamma) {
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this.seed = seed;
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this.gamma = gamma;
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}
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/**
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* Computes Stafford variant 13 of 64bit mix function.
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*/
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private static long mix64(long z) {
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z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L;
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z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
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return z ^ (z >>> 31);
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}
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/**
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* Returns the 32 high bits of Stafford variant 4 mix64 function as int.
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*/
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private static int mix32(long z) {
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z = (z ^ (z >>> 33)) * 0x62a9d9ed799705f5L;
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return (int)(((z ^ (z >>> 28)) * 0xcb24d0a5c88c35b3L) >>> 32);
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}
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/**
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* Returns the gamma value to use for a new split instance.
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*/
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private static long mixGamma(long z) {
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z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL; // MurmurHash3 mix constants
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z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
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z = (z ^ (z >>> 33)) | 1L; // force to be odd
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int n = Long.bitCount(z ^ (z >>> 1)); // ensure enough transitions
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return (n < 24) ? z ^ 0xaaaaaaaaaaaaaaaaL : z;
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}
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/**
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* Adds gamma to seed.
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*/
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private long nextSeed() {
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return seed += gamma;
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}
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/**
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* The seed generator for default constructors.
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*/
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private static final AtomicLong defaultGen = new AtomicLong(initialSeed());
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private static long initialSeed() {
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String pp = java.security.AccessController.doPrivileged(
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new sun.security.action.GetPropertyAction(
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"java.util.secureRandomSeed"));
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if (pp != null && pp.equalsIgnoreCase("true")) {
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byte[] seedBytes = java.security.SecureRandom.getSeed(8);
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long s = (long)(seedBytes[0]) & 0xffL;
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for (int i = 1; i < 8; ++i)
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s = (s << 8) | ((long)(seedBytes[i]) & 0xffL);
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return s;
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}
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return (mix64(System.currentTimeMillis()) ^
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mix64(System.nanoTime()));
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}
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// IllegalArgumentException messages
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static final String BadBound = "bound must be positive";
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static final String BadRange = "bound must be greater than origin";
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static final String BadSize = "size must be non-negative";
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/*
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* Internal versions of nextX methods used by streams, as well as
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* the public nextX(origin, bound) methods. These exist mainly to
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* avoid the need for multiple versions of stream spliterators
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* across the different exported forms of streams.
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*/
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/**
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* The form of nextLong used by LongStream Spliterators. If
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* origin is greater than bound, acts as unbounded form of
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* nextLong, else as bounded form.
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*
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* @param origin the least value, unless greater than bound
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* @param bound the upper bound (exclusive), must not equal origin
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* @return a pseudorandom value
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*/
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final long internalNextLong(long origin, long bound) {
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/*
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* Four Cases:
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*
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* 1. If the arguments indicate unbounded form, act as
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* nextLong().
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*
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* 2. If the range is an exact power of two, apply the
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* associated bit mask.
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*
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* 3. If the range is positive, loop to avoid potential bias
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* when the implicit nextLong() bound (2<sup>64</sup>) is not
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* evenly divisible by the range. The loop rejects candidates
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* computed from otherwise over-represented values. The
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* expected number of iterations under an ideal generator
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* varies from 1 to 2, depending on the bound. The loop itself
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* takes an unlovable form. Because the first candidate is
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* already available, we need a break-in-the-middle
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* construction, which is concisely but cryptically performed
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* within the while-condition of a body-less for loop.
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*
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* 4. Otherwise, the range cannot be represented as a positive
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* long. The loop repeatedly generates unbounded longs until
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* obtaining a candidate meeting constraints (with an expected
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* number of iterations of less than two).
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*/
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long r = mix64(nextSeed());
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if (origin < bound) {
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long n = bound - origin, m = n - 1;
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if ((n & m) == 0L) // power of two
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r = (r & m) + origin;
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else if (n > 0L) { // reject over-represented candidates
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for (long u = r >>> 1; // ensure nonnegative
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u + m - (r = u % n) < 0L; // rejection check
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u = mix64(nextSeed()) >>> 1) // retry
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;
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r += origin;
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}
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else { // range not representable as long
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while (r < origin || r >= bound)
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r = mix64(nextSeed());
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}
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}
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return r;
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}
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/**
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* The form of nextInt used by IntStream Spliterators.
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* Exactly the same as long version, except for types.
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*
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* @param origin the least value, unless greater than bound
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* @param bound the upper bound (exclusive), must not equal origin
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* @return a pseudorandom value
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*/
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final int internalNextInt(int origin, int bound) {
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int r = mix32(nextSeed());
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if (origin < bound) {
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int n = bound - origin, m = n - 1;
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if ((n & m) == 0)
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r = (r & m) + origin;
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else if (n > 0) {
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for (int u = r >>> 1;
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u + m - (r = u % n) < 0;
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u = mix32(nextSeed()) >>> 1)
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;
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r += origin;
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}
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else {
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while (r < origin || r >= bound)
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r = mix32(nextSeed());
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}
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}
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return r;
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}
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/**
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* The form of nextDouble used by DoubleStream Spliterators.
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*
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* @param origin the least value, unless greater than bound
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* @param bound the upper bound (exclusive), must not equal origin
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* @return a pseudorandom value
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*/
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final double internalNextDouble(double origin, double bound) {
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double r = (nextLong() >>> 11) * DOUBLE_UNIT;
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if (origin < bound) {
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r = r * (bound - origin) + origin;
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if (r >= bound) // correct for rounding
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r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
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}
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return r;
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}
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/* ---------------- public methods ---------------- */
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/**
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* Creates a new SplittableRandom instance using the specified
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* initial seed. SplittableRandom instances created with the same
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* seed in the same program generate identical sequences of values.
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*
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* @param seed the initial seed
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*/
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public SplittableRandom(long seed) {
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this(seed, GOLDEN_GAMMA);
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}
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/**
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* Creates a new SplittableRandom instance that is likely to
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* generate sequences of values that are statistically independent
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* of those of any other instances in the current program; and
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* may, and typically does, vary across program invocations.
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*/
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public SplittableRandom() { // emulate defaultGen.split()
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long s = defaultGen.getAndAdd(2 * GOLDEN_GAMMA);
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this.seed = mix64(s);
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this.gamma = mixGamma(s + GOLDEN_GAMMA);
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}
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/**
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* Constructs and returns a new SplittableRandom instance that
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* shares no mutable state with this instance. However, with very
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* high probability, the set of values collectively generated by
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* the two objects has the same statistical properties as if the
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* same quantity of values were generated by a single thread using
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* a single SplittableRandom object. Either or both of the two
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* objects may be further split using the {@code split()} method,
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* and the same expected statistical properties apply to the
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* entire set of generators constructed by such recursive
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* splitting.
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*
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* @return the new SplittableRandom instance
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*/
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public SplittableRandom split() {
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return new SplittableRandom(nextLong(), mixGamma(nextSeed()));
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}
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/**
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* Returns a pseudorandom {@code int} value.
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*
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* @return a pseudorandom {@code int} value
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*/
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public int nextInt() {
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return mix32(nextSeed());
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}
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/**
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* Returns a pseudorandom {@code int} value between zero (inclusive)
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* and the specified bound (exclusive).
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*
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* @param bound the upper bound (exclusive). Must be positive.
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* @return a pseudorandom {@code int} value between zero
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* (inclusive) and the bound (exclusive)
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* @throws IllegalArgumentException if {@code bound} is not positive
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*/
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public int nextInt(int bound) {
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if (bound <= 0)
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throw new IllegalArgumentException(BadBound);
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// Specialize internalNextInt for origin 0
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int r = mix32(nextSeed());
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int m = bound - 1;
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if ((bound & m) == 0) // power of two
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r &= m;
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else { // reject over-represented candidates
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for (int u = r >>> 1;
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u + m - (r = u % bound) < 0;
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u = mix32(nextSeed()) >>> 1)
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;
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}
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return r;
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}
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/**
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* Returns a pseudorandom {@code int} value between the specified
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* origin (inclusive) and the specified bound (exclusive).
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*
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* @param origin the least value returned
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* @param bound the upper bound (exclusive)
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* @return a pseudorandom {@code int} value between the origin
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* (inclusive) and the bound (exclusive)
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* @throws IllegalArgumentException if {@code origin} is greater than
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* or equal to {@code bound}
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*/
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public int nextInt(int origin, int bound) {
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if (origin >= bound)
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throw new IllegalArgumentException(BadRange);
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return internalNextInt(origin, bound);
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}
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/**
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* Returns a pseudorandom {@code long} value.
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*
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* @return a pseudorandom {@code long} value
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*/
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public long nextLong() {
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return mix64(nextSeed());
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}
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/**
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* Returns a pseudorandom {@code long} value between zero (inclusive)
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* and the specified bound (exclusive).
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*
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* @param bound the upper bound (exclusive). Must be positive.
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* @return a pseudorandom {@code long} value between zero
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* (inclusive) and the bound (exclusive)
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* @throws IllegalArgumentException if {@code bound} is not positive
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*/
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public long nextLong(long bound) {
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if (bound <= 0)
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throw new IllegalArgumentException(BadBound);
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// Specialize internalNextLong for origin 0
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long r = mix64(nextSeed());
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long m = bound - 1;
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if ((bound & m) == 0L) // power of two
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r &= m;
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else { // reject over-represented candidates
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for (long u = r >>> 1;
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u + m - (r = u % bound) < 0L;
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u = mix64(nextSeed()) >>> 1)
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;
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}
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return r;
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}
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/**
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* Returns a pseudorandom {@code long} value between the specified
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* origin (inclusive) and the specified bound (exclusive).
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*
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* @param origin the least value returned
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* @param bound the upper bound (exclusive)
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* @return a pseudorandom {@code long} value between the origin
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* (inclusive) and the bound (exclusive)
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* @throws IllegalArgumentException if {@code origin} is greater than
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* or equal to {@code bound}
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*/
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public long nextLong(long origin, long bound) {
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if (origin >= bound)
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throw new IllegalArgumentException(BadRange);
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return internalNextLong(origin, bound);
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}
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/**
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* Returns a pseudorandom {@code double} value between zero
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* (inclusive) and one (exclusive).
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*
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* @return a pseudorandom {@code double} value between zero
|
|
* (inclusive) and one (exclusive)
|
|
*/
|
|
public double nextDouble() {
|
|
return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT;
|
|
}
|
|
|
|
/**
|
|
* Returns a pseudorandom {@code double} value between 0.0
|
|
* (inclusive) and the specified bound (exclusive).
|
|
*
|
|
* @param bound the upper bound (exclusive). Must be positive.
|
|
* @return a pseudorandom {@code double} value between zero
|
|
* (inclusive) and the bound (exclusive)
|
|
* @throws IllegalArgumentException if {@code bound} is not positive
|
|
*/
|
|
public double nextDouble(double bound) {
|
|
if (!(bound > 0.0))
|
|
throw new IllegalArgumentException(BadBound);
|
|
double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound;
|
|
return (result < bound) ? result : // correct for rounding
|
|
Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
|
|
}
|
|
|
|
/**
|
|
* Returns a pseudorandom {@code double} value between the specified
|
|
* origin (inclusive) and bound (exclusive).
|
|
*
|
|
* @param origin the least value returned
|
|
* @param bound the upper bound (exclusive)
|
|
* @return a pseudorandom {@code double} value between the origin
|
|
* (inclusive) and the bound (exclusive)
|
|
* @throws IllegalArgumentException if {@code origin} is greater than
|
|
* or equal to {@code bound}
|
|
*/
|
|
public double nextDouble(double origin, double bound) {
|
|
if (!(origin < bound))
|
|
throw new IllegalArgumentException(BadRange);
|
|
return internalNextDouble(origin, bound);
|
|
}
|
|
|
|
/**
|
|
* Returns a pseudorandom {@code boolean} value.
|
|
*
|
|
* @return a pseudorandom {@code boolean} value
|
|
*/
|
|
public boolean nextBoolean() {
|
|
return mix32(nextSeed()) < 0;
|
|
}
|
|
|
|
// stream methods, coded in a way intended to better isolate for
|
|
// maintenance purposes the small differences across forms.
|
|
|
|
/**
|
|
* Returns a stream producing the given {@code streamSize} number
|
|
* of pseudorandom {@code int} values from this generator and/or
|
|
* one split from it.
|
|
*
|
|
* @param streamSize the number of values to generate
|
|
* @return a stream of pseudorandom {@code int} values
|
|
* @throws IllegalArgumentException if {@code streamSize} is
|
|
* less than zero
|
|
*/
|
|
public IntStream ints(long streamSize) {
|
|
if (streamSize < 0L)
|
|
throw new IllegalArgumentException(BadSize);
|
|
return StreamSupport.intStream
|
|
(new RandomIntsSpliterator
|
|
(this, 0L, streamSize, Integer.MAX_VALUE, 0),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns an effectively unlimited stream of pseudorandom {@code int}
|
|
* values from this generator and/or one split from it.
|
|
*
|
|
* @implNote This method is implemented to be equivalent to {@code
|
|
* ints(Long.MAX_VALUE)}.
|
|
*
|
|
* @return a stream of pseudorandom {@code int} values
|
|
*/
|
|
public IntStream ints() {
|
|
return StreamSupport.intStream
|
|
(new RandomIntsSpliterator
|
|
(this, 0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns a stream producing the given {@code streamSize} number
|
|
* of pseudorandom {@code int} values from this generator and/or one split
|
|
* from it; each value conforms to the given origin (inclusive) and bound
|
|
* (exclusive).
|
|
*
|
|
* @param streamSize the number of values to generate
|
|
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
* @param randomNumberBound the bound (exclusive) of each random value
|
|
* @return a stream of pseudorandom {@code int} values,
|
|
* each with the given origin (inclusive) and bound (exclusive)
|
|
* @throws IllegalArgumentException if {@code streamSize} is
|
|
* less than zero, or {@code randomNumberOrigin}
|
|
* is greater than or equal to {@code randomNumberBound}
|
|
*/
|
|
public IntStream ints(long streamSize, int randomNumberOrigin,
|
|
int randomNumberBound) {
|
|
if (streamSize < 0L)
|
|
throw new IllegalArgumentException(BadSize);
|
|
if (randomNumberOrigin >= randomNumberBound)
|
|
throw new IllegalArgumentException(BadRange);
|
|
return StreamSupport.intStream
|
|
(new RandomIntsSpliterator
|
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns an effectively unlimited stream of pseudorandom {@code
|
|
* int} values from this generator and/or one split from it; each value
|
|
* conforms to the given origin (inclusive) and bound (exclusive).
|
|
*
|
|
* @implNote This method is implemented to be equivalent to {@code
|
|
* ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
|
|
*
|
|
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
* @param randomNumberBound the bound (exclusive) of each random value
|
|
* @return a stream of pseudorandom {@code int} values,
|
|
* each with the given origin (inclusive) and bound (exclusive)
|
|
* @throws IllegalArgumentException if {@code randomNumberOrigin}
|
|
* is greater than or equal to {@code randomNumberBound}
|
|
*/
|
|
public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
|
|
if (randomNumberOrigin >= randomNumberBound)
|
|
throw new IllegalArgumentException(BadRange);
|
|
return StreamSupport.intStream
|
|
(new RandomIntsSpliterator
|
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns a stream producing the given {@code streamSize} number
|
|
* of pseudorandom {@code long} values from this generator and/or
|
|
* one split from it.
|
|
*
|
|
* @param streamSize the number of values to generate
|
|
* @return a stream of pseudorandom {@code long} values
|
|
* @throws IllegalArgumentException if {@code streamSize} is
|
|
* less than zero
|
|
*/
|
|
public LongStream longs(long streamSize) {
|
|
if (streamSize < 0L)
|
|
throw new IllegalArgumentException(BadSize);
|
|
return StreamSupport.longStream
|
|
(new RandomLongsSpliterator
|
|
(this, 0L, streamSize, Long.MAX_VALUE, 0L),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns an effectively unlimited stream of pseudorandom {@code
|
|
* long} values from this generator and/or one split from it.
|
|
*
|
|
* @implNote This method is implemented to be equivalent to {@code
|
|
* longs(Long.MAX_VALUE)}.
|
|
*
|
|
* @return a stream of pseudorandom {@code long} values
|
|
*/
|
|
public LongStream longs() {
|
|
return StreamSupport.longStream
|
|
(new RandomLongsSpliterator
|
|
(this, 0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns a stream producing the given {@code streamSize} number of
|
|
* pseudorandom {@code long} values from this generator and/or one split
|
|
* from it; each value conforms to the given origin (inclusive) and bound
|
|
* (exclusive).
|
|
*
|
|
* @param streamSize the number of values to generate
|
|
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
* @param randomNumberBound the bound (exclusive) of each random value
|
|
* @return a stream of pseudorandom {@code long} values,
|
|
* each with the given origin (inclusive) and bound (exclusive)
|
|
* @throws IllegalArgumentException if {@code streamSize} is
|
|
* less than zero, or {@code randomNumberOrigin}
|
|
* is greater than or equal to {@code randomNumberBound}
|
|
*/
|
|
public LongStream longs(long streamSize, long randomNumberOrigin,
|
|
long randomNumberBound) {
|
|
if (streamSize < 0L)
|
|
throw new IllegalArgumentException(BadSize);
|
|
if (randomNumberOrigin >= randomNumberBound)
|
|
throw new IllegalArgumentException(BadRange);
|
|
return StreamSupport.longStream
|
|
(new RandomLongsSpliterator
|
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns an effectively unlimited stream of pseudorandom {@code
|
|
* long} values from this generator and/or one split from it; each value
|
|
* conforms to the given origin (inclusive) and bound (exclusive).
|
|
*
|
|
* @implNote This method is implemented to be equivalent to {@code
|
|
* longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
|
|
*
|
|
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
* @param randomNumberBound the bound (exclusive) of each random value
|
|
* @return a stream of pseudorandom {@code long} values,
|
|
* each with the given origin (inclusive) and bound (exclusive)
|
|
* @throws IllegalArgumentException if {@code randomNumberOrigin}
|
|
* is greater than or equal to {@code randomNumberBound}
|
|
*/
|
|
public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
|
|
if (randomNumberOrigin >= randomNumberBound)
|
|
throw new IllegalArgumentException(BadRange);
|
|
return StreamSupport.longStream
|
|
(new RandomLongsSpliterator
|
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns a stream producing the given {@code streamSize} number of
|
|
* pseudorandom {@code double} values from this generator and/or one split
|
|
* from it; each value is between zero (inclusive) and one (exclusive).
|
|
*
|
|
* @param streamSize the number of values to generate
|
|
* @return a stream of {@code double} values
|
|
* @throws IllegalArgumentException if {@code streamSize} is
|
|
* less than zero
|
|
*/
|
|
public DoubleStream doubles(long streamSize) {
|
|
if (streamSize < 0L)
|
|
throw new IllegalArgumentException(BadSize);
|
|
return StreamSupport.doubleStream
|
|
(new RandomDoublesSpliterator
|
|
(this, 0L, streamSize, Double.MAX_VALUE, 0.0),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns an effectively unlimited stream of pseudorandom {@code
|
|
* double} values from this generator and/or one split from it; each value
|
|
* is between zero (inclusive) and one (exclusive).
|
|
*
|
|
* @implNote This method is implemented to be equivalent to {@code
|
|
* doubles(Long.MAX_VALUE)}.
|
|
*
|
|
* @return a stream of pseudorandom {@code double} values
|
|
*/
|
|
public DoubleStream doubles() {
|
|
return StreamSupport.doubleStream
|
|
(new RandomDoublesSpliterator
|
|
(this, 0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns a stream producing the given {@code streamSize} number of
|
|
* pseudorandom {@code double} values from this generator and/or one split
|
|
* from it; each value conforms to the given origin (inclusive) and bound
|
|
* (exclusive).
|
|
*
|
|
* @param streamSize the number of values to generate
|
|
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
* @param randomNumberBound the bound (exclusive) of each random value
|
|
* @return a stream of pseudorandom {@code double} values,
|
|
* each with the given origin (inclusive) and bound (exclusive)
|
|
* @throws IllegalArgumentException if {@code streamSize} is
|
|
* less than zero
|
|
* @throws IllegalArgumentException if {@code randomNumberOrigin}
|
|
* is greater than or equal to {@code randomNumberBound}
|
|
*/
|
|
public DoubleStream doubles(long streamSize, double randomNumberOrigin,
|
|
double randomNumberBound) {
|
|
if (streamSize < 0L)
|
|
throw new IllegalArgumentException(BadSize);
|
|
if (!(randomNumberOrigin < randomNumberBound))
|
|
throw new IllegalArgumentException(BadRange);
|
|
return StreamSupport.doubleStream
|
|
(new RandomDoublesSpliterator
|
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Returns an effectively unlimited stream of pseudorandom {@code
|
|
* double} values from this generator and/or one split from it; each value
|
|
* conforms to the given origin (inclusive) and bound (exclusive).
|
|
*
|
|
* @implNote This method is implemented to be equivalent to {@code
|
|
* doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
|
|
*
|
|
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
* @param randomNumberBound the bound (exclusive) of each random value
|
|
* @return a stream of pseudorandom {@code double} values,
|
|
* each with the given origin (inclusive) and bound (exclusive)
|
|
* @throws IllegalArgumentException if {@code randomNumberOrigin}
|
|
* is greater than or equal to {@code randomNumberBound}
|
|
*/
|
|
public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
|
|
if (!(randomNumberOrigin < randomNumberBound))
|
|
throw new IllegalArgumentException(BadRange);
|
|
return StreamSupport.doubleStream
|
|
(new RandomDoublesSpliterator
|
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
|
|
false);
|
|
}
|
|
|
|
/**
|
|
* Spliterator for int streams. We multiplex the four int
|
|
* versions into one class by treating a bound less than origin as
|
|
* unbounded, and also by treating "infinite" as equivalent to
|
|
* Long.MAX_VALUE. For splits, it uses the standard divide-by-two
|
|
* approach. The long and double versions of this class are
|
|
* identical except for types.
|
|
*/
|
|
static final class RandomIntsSpliterator implements Spliterator.OfInt {
|
|
final SplittableRandom rng;
|
|
long index;
|
|
final long fence;
|
|
final int origin;
|
|
final int bound;
|
|
RandomIntsSpliterator(SplittableRandom rng, long index, long fence,
|
|
int origin, int bound) {
|
|
this.rng = rng; this.index = index; this.fence = fence;
|
|
this.origin = origin; this.bound = bound;
|
|
}
|
|
|
|
public RandomIntsSpliterator trySplit() {
|
|
long i = index, m = (i + fence) >>> 1;
|
|
return (m <= i) ? null :
|
|
new RandomIntsSpliterator(rng.split(), i, index = m, origin, bound);
|
|
}
|
|
|
|
public long estimateSize() {
|
|
return fence - index;
|
|
}
|
|
|
|
public int characteristics() {
|
|
return (Spliterator.SIZED | Spliterator.SUBSIZED |
|
|
Spliterator.NONNULL | Spliterator.IMMUTABLE);
|
|
}
|
|
|
|
public boolean tryAdvance(IntConsumer consumer) {
|
|
if (consumer == null) throw new NullPointerException();
|
|
long i = index, f = fence;
|
|
if (i < f) {
|
|
consumer.accept(rng.internalNextInt(origin, bound));
|
|
index = i + 1;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
public void forEachRemaining(IntConsumer consumer) {
|
|
if (consumer == null) throw new NullPointerException();
|
|
long i = index, f = fence;
|
|
if (i < f) {
|
|
index = f;
|
|
SplittableRandom r = rng;
|
|
int o = origin, b = bound;
|
|
do {
|
|
consumer.accept(r.internalNextInt(o, b));
|
|
} while (++i < f);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Spliterator for long streams.
|
|
*/
|
|
static final class RandomLongsSpliterator implements Spliterator.OfLong {
|
|
final SplittableRandom rng;
|
|
long index;
|
|
final long fence;
|
|
final long origin;
|
|
final long bound;
|
|
RandomLongsSpliterator(SplittableRandom rng, long index, long fence,
|
|
long origin, long bound) {
|
|
this.rng = rng; this.index = index; this.fence = fence;
|
|
this.origin = origin; this.bound = bound;
|
|
}
|
|
|
|
public RandomLongsSpliterator trySplit() {
|
|
long i = index, m = (i + fence) >>> 1;
|
|
return (m <= i) ? null :
|
|
new RandomLongsSpliterator(rng.split(), i, index = m, origin, bound);
|
|
}
|
|
|
|
public long estimateSize() {
|
|
return fence - index;
|
|
}
|
|
|
|
public int characteristics() {
|
|
return (Spliterator.SIZED | Spliterator.SUBSIZED |
|
|
Spliterator.NONNULL | Spliterator.IMMUTABLE);
|
|
}
|
|
|
|
public boolean tryAdvance(LongConsumer consumer) {
|
|
if (consumer == null) throw new NullPointerException();
|
|
long i = index, f = fence;
|
|
if (i < f) {
|
|
consumer.accept(rng.internalNextLong(origin, bound));
|
|
index = i + 1;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
public void forEachRemaining(LongConsumer consumer) {
|
|
if (consumer == null) throw new NullPointerException();
|
|
long i = index, f = fence;
|
|
if (i < f) {
|
|
index = f;
|
|
SplittableRandom r = rng;
|
|
long o = origin, b = bound;
|
|
do {
|
|
consumer.accept(r.internalNextLong(o, b));
|
|
} while (++i < f);
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
/**
|
|
* Spliterator for double streams.
|
|
*/
|
|
static final class RandomDoublesSpliterator implements Spliterator.OfDouble {
|
|
final SplittableRandom rng;
|
|
long index;
|
|
final long fence;
|
|
final double origin;
|
|
final double bound;
|
|
RandomDoublesSpliterator(SplittableRandom rng, long index, long fence,
|
|
double origin, double bound) {
|
|
this.rng = rng; this.index = index; this.fence = fence;
|
|
this.origin = origin; this.bound = bound;
|
|
}
|
|
|
|
public RandomDoublesSpliterator trySplit() {
|
|
long i = index, m = (i + fence) >>> 1;
|
|
return (m <= i) ? null :
|
|
new RandomDoublesSpliterator(rng.split(), i, index = m, origin, bound);
|
|
}
|
|
|
|
public long estimateSize() {
|
|
return fence - index;
|
|
}
|
|
|
|
public int characteristics() {
|
|
return (Spliterator.SIZED | Spliterator.SUBSIZED |
|
|
Spliterator.NONNULL | Spliterator.IMMUTABLE);
|
|
}
|
|
|
|
public boolean tryAdvance(DoubleConsumer consumer) {
|
|
if (consumer == null) throw new NullPointerException();
|
|
long i = index, f = fence;
|
|
if (i < f) {
|
|
consumer.accept(rng.internalNextDouble(origin, bound));
|
|
index = i + 1;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
public void forEachRemaining(DoubleConsumer consumer) {
|
|
if (consumer == null) throw new NullPointerException();
|
|
long i = index, f = fence;
|
|
if (i < f) {
|
|
index = f;
|
|
SplittableRandom r = rng;
|
|
double o = origin, b = bound;
|
|
do {
|
|
consumer.accept(r.internalNextDouble(o, b));
|
|
} while (++i < f);
|
|
}
|
|
}
|
|
}
|
|
|
|
}
|