JDK 17 jdk.random.jmod - JDK Random Module
JDK 17 jdk.random.jmod is the JMOD file for JDK 17 Random module.
JDK 17 Random module compiled class files are stored in \fyicenter\jdk-17.0.5\jmods\jdk.random.jmod.
JDK 17 Random module compiled class files are also linked and stored in the \fyicenter\jdk-17.0.5\lib\modules JImage file.
JDK 17 Random module source code files are stored in \fyicenter\jdk-17.0.5\lib\src.zip\jdk.random.
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⏎ jdk/random/L64X128MixRandom.java
/*
* Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package jdk.random;
import java.util.concurrent.atomic.AtomicLong;
import java.util.random.RandomGenerator;
import jdk.internal.util.random.RandomSupport;
import jdk.internal.util.random.RandomSupport.AbstractSplittableWithBrineGenerator;
import jdk.internal.util.random.RandomSupport.RandomGeneratorProperties;
/**
* A "splittable" pseudorandom number generator (PRNG) whose period
* is roughly 2<sup>192</sup>. Class {@link L64X128MixRandom} implements
* interfaces {@link RandomGenerator} and {@link SplittableGenerator},
* and therefore supports methods for producing pseudorandomly chosen
* values of type {@code int}, {@code long}, {@code float}, {@code double},
* and {@code boolean} (and for producing streams of pseudorandomly chosen
* numbers of type {@code int}, {@code long}, and {@code double}),
* as well as methods for creating new split-off {@link L64X128MixRandom}
* objects or streams of such objects.
*
* <p>The {@link L64X128MixRandom} algorithm is a specific member of
* the LXM family of algorithms for pseudorandom number generators;
* for more information, see the documentation for package
* {@link jdk.random}. Each instance of {@link L64X128MixRandom}
* has 192 bits of state plus one 64-bit instance-specific parameter.
*
* <p>If two instances of {@link L64X128MixRandom} are created with
* the same seed within the same program execution, and the same
* sequence of method calls is made for each, they will generate and
* return identical sequences of values.
*
* <p>As with {@link java.util.SplittableRandom}, instances of
* {@link L64X128MixRandom} are <em>not</em> thread-safe. They are
* designed to be split, not shared, across threads (see the {@link #split}
* method). For example, a {@link java.util.concurrent.ForkJoinTask}
* fork/join-style computation using random numbers might include a
* construction of the form
* {@code new Subtask(someL64X128MixRandom.split()).fork()}.
*
* <p>This class provides additional methods for generating random
* streams, that employ the above techniques when used in
* {@code stream.parallel()} mode.
*
* <p>Instances of {@link L64X128MixRandom} are not cryptographically
* secure. Consider instead using {@link java.security.SecureRandom}
* in security-sensitive applications. Additionally,
* default-constructed instances do not use a cryptographically random
* seed unless the {@linkplain System#getProperty system property}
* {@code java.util.secureRandomSeed} is set to {@code true}.
*
* @since 17
*
*/
@RandomGeneratorProperties(
name = "L64X128MixRandom",
group = "LXM",
i = 128, j = 1, k = 64,
equidistribution = 2
)
public final class L64X128MixRandom extends AbstractSplittableWithBrineGenerator {
/*
* Implementation Overview.
*
* The split operation uses the current generator to choose four new 64-bit
* long values that are then used to initialize the parameter `a` and the
* state variables `s`, `x0`, and `x1` for a newly constructed generator.
*
* With extremely high probability, no two generators so chosen
* will have the same `a` parameter, and testing has indicated
* that the values generated by two instances of {@link L64X128MixRandom}
* will be (approximately) independent if have different values for `a`.
*
* The default (no-argument) constructor, in essence, uses
* "defaultGen" to generate four new 64-bit values for the same
* purpose. Multiple generators created in this way will certainly
* differ in their `a` parameters. The defaultGen state must be accessed
* in a thread-safe manner, so we use an AtomicLong to represent
* this state. To bootstrap the defaultGen, we start off using a
* seed based on current time unless the
* java.util.secureRandomSeed property is set. This serves as a
* slimmed-down (and insecure) variant of SecureRandom that also
* avoids stalls that may occur when using /dev/random.
*
* File organization: First static fields, then instance
* fields, then constructors, then instance methods.
*/
/* ---------------- static fields ---------------- */
/**
* The seed generator for default constructors.
*/
private static final AtomicLong defaultGen = new AtomicLong(RandomSupport.initialSeed());
/*
* Multiplier used in the LCG portion of the algorithm.
* Chosen based on research by Sebastiano Vigna and Guy Steele (2019).
* The spectral scores for dimensions 2 through 8 for the multiplier 0xd1342543de82ef95L
* are [0.958602, 0.937479, 0.870757, 0.822326, 0.820405, 0.813065, 0.760215].
*/
private static final long M = 0xd1342543de82ef95L;
/* ---------------- instance fields ---------------- */
/**
* The parameter that is used as an additive constant for the LCG.
* Must be odd.
*/
private final long a;
/**
* The per-instance state: s for the LCG; x0 and x1 for the XBG.
* At least one of x0 and x1 must be nonzero.
*/
private long s, x0, x1;
/* ---------------- constructors ---------------- */
/**
* Basic constructor that initializes all fields from parameters.
* It then adjusts the field values if necessary to ensure that
* all constraints on the values of fields are met.
*
* @param a additive parameter for the LCG
* @param s initial state for the LCG
* @param x0 first word of the initial state for the XBG
* @param x1 second word of the initial state for the XBG
*/
public L64X128MixRandom(long a, long s, long x0, long x1) {
// Force a to be odd.
this.a = a | 1;
this.s = s;
this.x0 = x0;
this.x1 = x1;
// If x0 and x1 are both zero, we must choose nonzero values.
if ((x0 | x1) == 0) {
long v = s;
// At least one of the two values generated here will be nonzero.
this.x0 = RandomSupport.mixStafford13(v += RandomSupport.GOLDEN_RATIO_64);
this.x1 = RandomSupport.mixStafford13(v + RandomSupport.GOLDEN_RATIO_64);
}
}
/**
* Creates a new instance of {@link L64X128MixRandom} using the
* specified {@code long} value as the initial seed. Instances of
* {@link L64X128MixRandom} created with the same seed in the same
* program generate identical sequences of values.
*
* @param seed the initial seed
*/
public L64X128MixRandom(long seed) {
// Using a value with irregularly spaced 1-bits to xor the seed
// argument tends to improve "pedestrian" seeds such as 0 or
// other small integers. We may as well use SILVER_RATIO_64.
//
// The seed is hashed by mixMurmur64 to produce the `a` parameter.
// The seed is hashed by mixStafford13 to produce the initial `x0`,
// which will then be used to produce the first generated value.
// Then x1 is filled in as if by a SplitMix PRNG with
// GOLDEN_RATIO_64 as the gamma value and mixStafford13 as the mixer.
this(RandomSupport.mixMurmur64(seed ^= RandomSupport.SILVER_RATIO_64),
1,
RandomSupport.mixStafford13(seed),
RandomSupport.mixStafford13(seed + RandomSupport.GOLDEN_RATIO_64));
}
/**
* Creates a new instance of {@link L64X128MixRandom} that is likely to
* generate sequences of values that are statistically independent
* of those of any other instances in the current program execution,
* but may, and typically does, vary across program invocations.
*/
public L64X128MixRandom() {
// Using GOLDEN_RATIO_64 here gives us a good Weyl sequence of values.
this(defaultGen.getAndAdd(RandomSupport.GOLDEN_RATIO_64));
}
/**
* Creates a new instance of {@link L64X128MixRandom} using the specified array of
* initial seed bytes. Instances of {@link L64X128MixRandom} created with the same
* seed array in the same program execution generate identical sequences of values.
*
* @param seed the initial seed
*/
public L64X128MixRandom(byte[] seed) {
// Convert the seed to 4 long values, of which the last 2 are not all zero.
long[] data = RandomSupport.convertSeedBytesToLongs(seed, 4, 2);
long a = data[0], s = data[1], x0 = data[2], x1 = data[3];
// Force a to be odd.
this.a = a | 1;
this.s = s;
this.x0 = x0;
this.x1 = x1;
}
/* ---------------- public methods ---------------- */
@Override
public SplittableGenerator split(SplittableGenerator source, long brine) {
// Pick a new instance "at random", but use the brine for `a`.
return new L64X128MixRandom(brine << 1, source.nextLong(),
source.nextLong(), source.nextLong());
}
@Override
public long nextLong() {
// Compute the result based on current state information
// (this allows the computation to be overlapped with state update).
final long result = RandomSupport.mixLea64(s + x0);
// Update the LCG subgenerator
s = M * s + a;
// Update the XBG subgenerator
long q0 = x0, q1 = x1;
{ // xoroshiro128v1_0
q1 ^= q0;
q0 = Long.rotateLeft(q0, 24);
q0 = q0 ^ q1 ^ (q1 << 16);
q1 = Long.rotateLeft(q1, 37);
}
x0 = q0; x1 = q1;
return result;
}
}
⏎ jdk/random/L64X128MixRandom.java
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File name: jdk.random-17.0.5-src.zip File size: 40593 bytes Release date: 2022-09-13 Download
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