| /* |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* |
| * This file is available under and governed by the GNU General Public |
| * License version 2 only, as published by the Free Software Foundation. |
| * However, the following notice accompanied the original version of this |
| * file: |
| * |
| * Written by Doug Lea with assistance from members of JCP JSR-166 |
| * Expert Group and released to the public domain, as explained at |
| * http://creativecommons.org/publicdomain/zero/1.0/ |
| */ |
| |
| package java.util.concurrent; |
| |
| import java.io.ObjectStreamField; |
| import java.util.Random; |
| import java.util.Spliterator; |
| import java.util.concurrent.atomic.AtomicInteger; |
| import java.util.concurrent.atomic.AtomicLong; |
| import java.util.function.DoubleConsumer; |
| import java.util.function.IntConsumer; |
| import java.util.function.LongConsumer; |
| import java.util.stream.DoubleStream; |
| import java.util.stream.IntStream; |
| import java.util.stream.LongStream; |
| import java.util.stream.StreamSupport; |
| |
| /** |
| * A random number generator isolated to the current thread. Like the |
| * global {@link java.util.Random} generator used by the {@link |
| * java.lang.Math} class, a {@code ThreadLocalRandom} is initialized |
| * with an internally generated seed that may not otherwise be |
| * modified. When applicable, use of {@code ThreadLocalRandom} rather |
| * than shared {@code Random} objects in concurrent programs will |
| * typically encounter much less overhead and contention. Use of |
| * {@code ThreadLocalRandom} is particularly appropriate when multiple |
| * tasks (for example, each a {@link ForkJoinTask}) use random numbers |
| * in parallel in thread pools. |
| * |
| * <p>Usages of this class should typically be of the form: |
| * {@code ThreadLocalRandom.current().nextX(...)} (where |
| * {@code X} is {@code Int}, {@code Long}, etc). |
| * When all usages are of this form, it is never possible to |
| * accidently share a {@code ThreadLocalRandom} across multiple threads. |
| * |
| * <p>This class also provides additional commonly used bounded random |
| * generation methods. |
| * |
| * <p>Instances of {@code ThreadLocalRandom} 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 1.7 |
| * @author Doug Lea |
| */ |
| public class ThreadLocalRandom extends Random { |
| /* |
| * This class implements the java.util.Random API (and subclasses |
| * Random) using a single static instance that accesses random |
| * number state held in class Thread (primarily, field |
| * threadLocalRandomSeed). In doing so, it also provides a home |
| * for managing package-private utilities that rely on exactly the |
| * same state as needed to maintain the ThreadLocalRandom |
| * instances. We leverage the need for an initialization flag |
| * field to also use it as a "probe" -- a self-adjusting thread |
| * hash used for contention avoidance, as well as a secondary |
| * simpler (xorShift) random seed that is conservatively used to |
| * avoid otherwise surprising users by hijacking the |
| * ThreadLocalRandom sequence. The dual use is a marriage of |
| * convenience, but is a simple and efficient way of reducing |
| * application-level overhead and footprint of most concurrent |
| * programs. |
| * |
| * Even though this class subclasses java.util.Random, it uses the |
| * same basic algorithm as java.util.SplittableRandom. (See its |
| * internal documentation for explanations, which are not repeated |
| * here.) Because ThreadLocalRandoms are not splittable |
| * though, we use only a single 64bit gamma. |
| * |
| * Because this class is in a different package than class Thread, |
| * field access methods use Unsafe to bypass access control rules. |
| * To conform to the requirements of the Random superclass |
| * constructor, the common static ThreadLocalRandom maintains an |
| * "initialized" field for the sake of rejecting user calls to |
| * setSeed while still allowing a call from constructor. Note |
| * that serialization is completely unnecessary because there is |
| * only a static singleton. But we generate a serial form |
| * containing "rnd" and "initialized" fields to ensure |
| * compatibility across versions. |
| * |
| * Implementations of non-core methods are mostly the same as in |
| * SplittableRandom, that were in part derived from a previous |
| * version of this class. |
| * |
| * The nextLocalGaussian ThreadLocal supports the very rarely used |
| * nextGaussian method by providing a holder for the second of a |
| * pair of them. As is true for the base class version of this |
| * method, this time/space tradeoff is probably never worthwhile, |
| * but we provide identical statistical properties. |
| */ |
| |
| private static long mix64(long z) { |
| z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL; |
| z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L; |
| return z ^ (z >>> 33); |
| } |
| |
| private static int mix32(long z) { |
| z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL; |
| return (int)(((z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L) >>> 32); |
| } |
| |
| /** |
| * Field used only during singleton initialization. |
| * True when constructor completes. |
| */ |
| boolean initialized; |
| |
| /** Constructor used only for static singleton */ |
| private ThreadLocalRandom() { |
| initialized = true; // false during super() call |
| } |
| |
| /** |
| * Initialize Thread fields for the current thread. Called only |
| * when Thread.threadLocalRandomProbe is zero, indicating that a |
| * thread local seed value needs to be generated. Note that even |
| * though the initialization is purely thread-local, we need to |
| * rely on (static) atomic generators to initialize the values. |
| */ |
| static final void localInit() { |
| int p = probeGenerator.addAndGet(PROBE_INCREMENT); |
| int probe = (p == 0) ? 1 : p; // skip 0 |
| long seed = mix64(seeder.getAndAdd(SEEDER_INCREMENT)); |
| Thread t = Thread.currentThread(); |
| U.putLong(t, SEED, seed); |
| U.putInt(t, PROBE, probe); |
| } |
| |
| /** |
| * Returns the current thread's {@code ThreadLocalRandom}. |
| * |
| * @return the current thread's {@code ThreadLocalRandom} |
| */ |
| public static ThreadLocalRandom current() { |
| if (U.getInt(Thread.currentThread(), PROBE) == 0) |
| localInit(); |
| return instance; |
| } |
| |
| /** |
| * Throws {@code UnsupportedOperationException}. Setting seeds in |
| * this generator is not supported. |
| * |
| * @throws UnsupportedOperationException always |
| */ |
| public void setSeed(long seed) { |
| // only allow call from super() constructor |
| if (initialized) |
| throw new UnsupportedOperationException(); |
| } |
| |
| final long nextSeed() { |
| Thread t; long r; // read and update per-thread seed |
| U.putLong(t = Thread.currentThread(), SEED, |
| r = U.getLong(t, SEED) + GAMMA); |
| return r; |
| } |
| |
| // We must define this, but never use it. |
| protected int next(int bits) { |
| return (int)(mix64(nextSeed()) >>> (64 - bits)); |
| } |
| |
| /** |
| * The form of nextLong used by LongStream Spliterators. If |
| * origin is greater than bound, acts as unbounded form of |
| * nextLong, else as bounded form. |
| * |
| * @param origin the least value, unless greater than bound |
| * @param bound the upper bound (exclusive), must not equal origin |
| * @return a pseudorandom value |
| */ |
| final long internalNextLong(long origin, long bound) { |
| long r = mix64(nextSeed()); |
| if (origin < bound) { |
| long n = bound - origin, m = n - 1; |
| if ((n & m) == 0L) // power of two |
| r = (r & m) + origin; |
| else if (n > 0L) { // reject over-represented candidates |
| for (long u = r >>> 1; // ensure nonnegative |
| u + m - (r = u % n) < 0L; // rejection check |
| u = mix64(nextSeed()) >>> 1) // retry |
| ; |
| r += origin; |
| } |
| else { // range not representable as long |
| while (r < origin || r >= bound) |
| r = mix64(nextSeed()); |
| } |
| } |
| return r; |
| } |
| |
| /** |
| * The form of nextInt used by IntStream Spliterators. |
| * Exactly the same as long version, except for types. |
| * |
| * @param origin the least value, unless greater than bound |
| * @param bound the upper bound (exclusive), must not equal origin |
| * @return a pseudorandom value |
| */ |
| final int internalNextInt(int origin, int bound) { |
| int r = mix32(nextSeed()); |
| if (origin < bound) { |
| int n = bound - origin, m = n - 1; |
| if ((n & m) == 0) |
| r = (r & m) + origin; |
| else if (n > 0) { |
| for (int u = r >>> 1; |
| u + m - (r = u % n) < 0; |
| u = mix32(nextSeed()) >>> 1) |
| ; |
| r += origin; |
| } |
| else { |
| while (r < origin || r >= bound) |
| r = mix32(nextSeed()); |
| } |
| } |
| return r; |
| } |
| |
| /** |
| * The form of nextDouble used by DoubleStream Spliterators. |
| * |
| * @param origin the least value, unless greater than bound |
| * @param bound the upper bound (exclusive), must not equal origin |
| * @return a pseudorandom value |
| */ |
| final double internalNextDouble(double origin, double bound) { |
| double r = (nextLong() >>> 11) * DOUBLE_UNIT; |
| if (origin < bound) { |
| r = r * (bound - origin) + origin; |
| if (r >= bound) // correct for rounding |
| r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
| } |
| return r; |
| } |
| |
| /** |
| * Returns a pseudorandom {@code int} value. |
| * |
| * @return a pseudorandom {@code int} value |
| */ |
| public int nextInt() { |
| return mix32(nextSeed()); |
| } |
| |
| /** |
| * Returns a pseudorandom {@code int} value between zero (inclusive) |
| * and the specified bound (exclusive). |
| * |
| * @param bound the upper bound (exclusive). Must be positive. |
| * @return a pseudorandom {@code int} value between zero |
| * (inclusive) and the bound (exclusive) |
| * @throws IllegalArgumentException if {@code bound} is not positive |
| */ |
| public int nextInt(int bound) { |
| if (bound <= 0) |
| throw new IllegalArgumentException(BAD_BOUND); |
| int r = mix32(nextSeed()); |
| int m = bound - 1; |
| if ((bound & m) == 0) // power of two |
| r &= m; |
| else { // reject over-represented candidates |
| for (int u = r >>> 1; |
| u + m - (r = u % bound) < 0; |
| u = mix32(nextSeed()) >>> 1) |
| ; |
| } |
| return r; |
| } |
| |
| /** |
| * Returns a pseudorandom {@code int} value between the specified |
| * origin (inclusive) and the specified bound (exclusive). |
| * |
| * @param origin the least value returned |
| * @param bound the upper bound (exclusive) |
| * @return a pseudorandom {@code int} value between the origin |
| * (inclusive) and the bound (exclusive) |
| * @throws IllegalArgumentException if {@code origin} is greater than |
| * or equal to {@code bound} |
| */ |
| public int nextInt(int origin, int bound) { |
| if (origin >= bound) |
| throw new IllegalArgumentException(BAD_RANGE); |
| return internalNextInt(origin, bound); |
| } |
| |
| /** |
| * Returns a pseudorandom {@code long} value. |
| * |
| * @return a pseudorandom {@code long} value |
| */ |
| public long nextLong() { |
| return mix64(nextSeed()); |
| } |
| |
| /** |
| * Returns a pseudorandom {@code long} value between zero (inclusive) |
| * and the specified bound (exclusive). |
| * |
| * @param bound the upper bound (exclusive). Must be positive. |
| * @return a pseudorandom {@code long} value between zero |
| * (inclusive) and the bound (exclusive) |
| * @throws IllegalArgumentException if {@code bound} is not positive |
| */ |
| public long nextLong(long bound) { |
| if (bound <= 0) |
| throw new IllegalArgumentException(BAD_BOUND); |
| long r = mix64(nextSeed()); |
| long m = bound - 1; |
| if ((bound & m) == 0L) // power of two |
| r &= m; |
| else { // reject over-represented candidates |
| for (long u = r >>> 1; |
| u + m - (r = u % bound) < 0L; |
| u = mix64(nextSeed()) >>> 1) |
| ; |
| } |
| return r; |
| } |
| |
| /** |
| * Returns a pseudorandom {@code long} value between the specified |
| * origin (inclusive) and the specified bound (exclusive). |
| * |
| * @param origin the least value returned |
| * @param bound the upper bound (exclusive) |
| * @return a pseudorandom {@code long} value between the origin |
| * (inclusive) and the bound (exclusive) |
| * @throws IllegalArgumentException if {@code origin} is greater than |
| * or equal to {@code bound} |
| */ |
| public long nextLong(long origin, long bound) { |
| if (origin >= bound) |
| throw new IllegalArgumentException(BAD_RANGE); |
| return internalNextLong(origin, bound); |
| } |
| |
| /** |
| * Returns a pseudorandom {@code double} value between zero |
| * (inclusive) and one (exclusive). |
| * |
| * @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(BAD_BOUND); |
| 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(BAD_RANGE); |
| return internalNextDouble(origin, bound); |
| } |
| |
| /** |
| * Returns a pseudorandom {@code boolean} value. |
| * |
| * @return a pseudorandom {@code boolean} value |
| */ |
| public boolean nextBoolean() { |
| return mix32(nextSeed()) < 0; |
| } |
| |
| /** |
| * Returns a pseudorandom {@code float} value between zero |
| * (inclusive) and one (exclusive). |
| * |
| * @return a pseudorandom {@code float} value between zero |
| * (inclusive) and one (exclusive) |
| */ |
| public float nextFloat() { |
| return (mix32(nextSeed()) >>> 8) * FLOAT_UNIT; |
| } |
| |
| public double nextGaussian() { |
| // Use nextLocalGaussian instead of nextGaussian field |
| Double d = nextLocalGaussian.get(); |
| if (d != null) { |
| nextLocalGaussian.set(null); |
| return d.doubleValue(); |
| } |
| double v1, v2, s; |
| do { |
| v1 = 2 * nextDouble() - 1; // between -1 and 1 |
| v2 = 2 * nextDouble() - 1; // between -1 and 1 |
| s = v1 * v1 + v2 * v2; |
| } while (s >= 1 || s == 0); |
| double multiplier = StrictMath.sqrt(-2 * StrictMath.log(s)/s); |
| nextLocalGaussian.set(new Double(v2 * multiplier)); |
| return v1 * multiplier; |
| } |
| |
| // 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. |
| * |
| * @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 |
| * @since 1.8 |
| */ |
| public IntStream ints(long streamSize) { |
| if (streamSize < 0L) |
| throw new IllegalArgumentException(BAD_SIZE); |
| return StreamSupport.intStream |
| (new RandomIntsSpliterator |
| (0L, streamSize, Integer.MAX_VALUE, 0), |
| false); |
| } |
| |
| /** |
| * Returns an effectively unlimited stream of pseudorandom {@code int} |
| * values. |
| * |
| * @implNote This method is implemented to be equivalent to {@code |
| * ints(Long.MAX_VALUE)}. |
| * |
| * @return a stream of pseudorandom {@code int} values |
| * @since 1.8 |
| */ |
| public IntStream ints() { |
| return StreamSupport.intStream |
| (new RandomIntsSpliterator |
| (0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0), |
| false); |
| } |
| |
| /** |
| * Returns a stream producing the given {@code streamSize} number |
| * of pseudorandom {@code int} values, each conforming 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} |
| * @since 1.8 |
| */ |
| public IntStream ints(long streamSize, int randomNumberOrigin, |
| int randomNumberBound) { |
| if (streamSize < 0L) |
| throw new IllegalArgumentException(BAD_SIZE); |
| if (randomNumberOrigin >= randomNumberBound) |
| throw new IllegalArgumentException(BAD_RANGE); |
| return StreamSupport.intStream |
| (new RandomIntsSpliterator |
| (0L, streamSize, randomNumberOrigin, randomNumberBound), |
| false); |
| } |
| |
| /** |
| * Returns an effectively unlimited stream of pseudorandom {@code |
| * int} values, each conforming 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} |
| * @since 1.8 |
| */ |
| public IntStream ints(int randomNumberOrigin, int randomNumberBound) { |
| if (randomNumberOrigin >= randomNumberBound) |
| throw new IllegalArgumentException(BAD_RANGE); |
| return StreamSupport.intStream |
| (new RandomIntsSpliterator |
| (0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
| false); |
| } |
| |
| /** |
| * Returns a stream producing the given {@code streamSize} number of |
| * pseudorandom {@code long} values. |
| * |
| * @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 |
| * @since 1.8 |
| */ |
| public LongStream longs(long streamSize) { |
| if (streamSize < 0L) |
| throw new IllegalArgumentException(BAD_SIZE); |
| return StreamSupport.longStream |
| (new RandomLongsSpliterator |
| (0L, streamSize, Long.MAX_VALUE, 0L), |
| false); |
| } |
| |
| /** |
| * Returns an effectively unlimited stream of pseudorandom {@code long} |
| * values. |
| * |
| * @implNote This method is implemented to be equivalent to {@code |
| * longs(Long.MAX_VALUE)}. |
| * |
| * @return a stream of pseudorandom {@code long} values |
| * @since 1.8 |
| */ |
| public LongStream longs() { |
| return StreamSupport.longStream |
| (new RandomLongsSpliterator |
| (0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L), |
| false); |
| } |
| |
| /** |
| * Returns a stream producing the given {@code streamSize} number of |
| * pseudorandom {@code long}, each conforming 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} |
| * @since 1.8 |
| */ |
| public LongStream longs(long streamSize, long randomNumberOrigin, |
| long randomNumberBound) { |
| if (streamSize < 0L) |
| throw new IllegalArgumentException(BAD_SIZE); |
| if (randomNumberOrigin >= randomNumberBound) |
| throw new IllegalArgumentException(BAD_RANGE); |
| return StreamSupport.longStream |
| (new RandomLongsSpliterator |
| (0L, streamSize, randomNumberOrigin, randomNumberBound), |
| false); |
| } |
| |
| /** |
| * Returns an effectively unlimited stream of pseudorandom {@code |
| * long} values, each conforming 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} |
| * @since 1.8 |
| */ |
| public LongStream longs(long randomNumberOrigin, long randomNumberBound) { |
| if (randomNumberOrigin >= randomNumberBound) |
| throw new IllegalArgumentException(BAD_RANGE); |
| return StreamSupport.longStream |
| (new RandomLongsSpliterator |
| (0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
| false); |
| } |
| |
| /** |
| * Returns a stream producing the given {@code streamSize} number of |
| * pseudorandom {@code double} values, each 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 |
| * @since 1.8 |
| */ |
| public DoubleStream doubles(long streamSize) { |
| if (streamSize < 0L) |
| throw new IllegalArgumentException(BAD_SIZE); |
| return StreamSupport.doubleStream |
| (new RandomDoublesSpliterator |
| (0L, streamSize, Double.MAX_VALUE, 0.0), |
| false); |
| } |
| |
| /** |
| * Returns an effectively unlimited stream of pseudorandom {@code |
| * double} values, each 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 |
| * @since 1.8 |
| */ |
| public DoubleStream doubles() { |
| return StreamSupport.doubleStream |
| (new RandomDoublesSpliterator |
| (0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0), |
| false); |
| } |
| |
| /** |
| * Returns a stream producing the given {@code streamSize} number of |
| * pseudorandom {@code double} values, each conforming 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} |
| * @since 1.8 |
| */ |
| public DoubleStream doubles(long streamSize, double randomNumberOrigin, |
| double randomNumberBound) { |
| if (streamSize < 0L) |
| throw new IllegalArgumentException(BAD_SIZE); |
| if (!(randomNumberOrigin < randomNumberBound)) |
| throw new IllegalArgumentException(BAD_RANGE); |
| return StreamSupport.doubleStream |
| (new RandomDoublesSpliterator |
| (0L, streamSize, randomNumberOrigin, randomNumberBound), |
| false); |
| } |
| |
| /** |
| * Returns an effectively unlimited stream of pseudorandom {@code |
| * double} values, each conforming 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} |
| * @since 1.8 |
| */ |
| public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) { |
| if (!(randomNumberOrigin < randomNumberBound)) |
| throw new IllegalArgumentException(BAD_RANGE); |
| return StreamSupport.doubleStream |
| (new RandomDoublesSpliterator |
| (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. |
| */ |
| private static final class RandomIntsSpliterator |
| implements Spliterator.OfInt { |
| long index; |
| final long fence; |
| final int origin; |
| final int bound; |
| RandomIntsSpliterator(long index, long fence, |
| int origin, int bound) { |
| 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(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(ThreadLocalRandom.current().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; |
| int o = origin, b = bound; |
| ThreadLocalRandom rng = ThreadLocalRandom.current(); |
| do { |
| consumer.accept(rng.internalNextInt(o, b)); |
| } while (++i < f); |
| } |
| } |
| } |
| |
| /** |
| * Spliterator for long streams. |
| */ |
| private static final class RandomLongsSpliterator |
| implements Spliterator.OfLong { |
| long index; |
| final long fence; |
| final long origin; |
| final long bound; |
| RandomLongsSpliterator(long index, long fence, |
| long origin, long bound) { |
| 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(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(ThreadLocalRandom.current().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; |
| long o = origin, b = bound; |
| ThreadLocalRandom rng = ThreadLocalRandom.current(); |
| do { |
| consumer.accept(rng.internalNextLong(o, b)); |
| } while (++i < f); |
| } |
| } |
| |
| } |
| |
| /** |
| * Spliterator for double streams. |
| */ |
| private static final class RandomDoublesSpliterator |
| implements Spliterator.OfDouble { |
| long index; |
| final long fence; |
| final double origin; |
| final double bound; |
| RandomDoublesSpliterator(long index, long fence, |
| double origin, double bound) { |
| 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(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(ThreadLocalRandom.current().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; |
| double o = origin, b = bound; |
| ThreadLocalRandom rng = ThreadLocalRandom.current(); |
| do { |
| consumer.accept(rng.internalNextDouble(o, b)); |
| } while (++i < f); |
| } |
| } |
| } |
| |
| |
| // Within-package utilities |
| |
| /* |
| * Descriptions of the usages of the methods below can be found in |
| * the classes that use them. Briefly, a thread's "probe" value is |
| * a non-zero hash code that (probably) does not collide with |
| * other existing threads with respect to any power of two |
| * collision space. When it does collide, it is pseudo-randomly |
| * adjusted (using a Marsaglia XorShift). The nextSecondarySeed |
| * method is used in the same contexts as ThreadLocalRandom, but |
| * only for transient usages such as random adaptive spin/block |
| * sequences for which a cheap RNG suffices and for which it could |
| * in principle disrupt user-visible statistical properties of the |
| * main ThreadLocalRandom if we were to use it. |
| * |
| * Note: Because of package-protection issues, versions of some |
| * these methods also appear in some subpackage classes. |
| */ |
| |
| /** |
| * Returns the probe value for the current thread without forcing |
| * initialization. Note that invoking ThreadLocalRandom.current() |
| * can be used to force initialization on zero return. |
| */ |
| static final int getProbe() { |
| return U.getInt(Thread.currentThread(), PROBE); |
| } |
| |
| /** |
| * Pseudo-randomly advances and records the given probe value for the |
| * given thread. |
| */ |
| static final int advanceProbe(int probe) { |
| probe ^= probe << 13; // xorshift |
| probe ^= probe >>> 17; |
| probe ^= probe << 5; |
| U.putInt(Thread.currentThread(), PROBE, probe); |
| return probe; |
| } |
| |
| /** |
| * Returns the pseudo-randomly initialized or updated secondary seed. |
| */ |
| static final int nextSecondarySeed() { |
| int r; |
| Thread t = Thread.currentThread(); |
| if ((r = U.getInt(t, SECONDARY)) != 0) { |
| r ^= r << 13; // xorshift |
| r ^= r >>> 17; |
| r ^= r << 5; |
| } |
| else if ((r = mix32(seeder.getAndAdd(SEEDER_INCREMENT))) == 0) |
| r = 1; // avoid zero |
| U.putInt(t, SECONDARY, r); |
| return r; |
| } |
| |
| // Serialization support |
| |
| private static final long serialVersionUID = -5851777807851030925L; |
| |
| /** |
| * @serialField rnd long |
| * seed for random computations |
| * @serialField initialized boolean |
| * always true |
| */ |
| private static final ObjectStreamField[] serialPersistentFields = { |
| new ObjectStreamField("rnd", long.class), |
| new ObjectStreamField("initialized", boolean.class), |
| }; |
| |
| /** |
| * Saves the {@code ThreadLocalRandom} to a stream (that is, serializes it). |
| * @param s the stream |
| * @throws java.io.IOException if an I/O error occurs |
| */ |
| private void writeObject(java.io.ObjectOutputStream s) |
| throws java.io.IOException { |
| |
| java.io.ObjectOutputStream.PutField fields = s.putFields(); |
| fields.put("rnd", U.getLong(Thread.currentThread(), SEED)); |
| fields.put("initialized", true); |
| s.writeFields(); |
| } |
| |
| /** |
| * Returns the {@link #current() current} thread's {@code ThreadLocalRandom}. |
| * @return the {@link #current() current} thread's {@code ThreadLocalRandom} |
| */ |
| private Object readResolve() { |
| return current(); |
| } |
| |
| // Static initialization |
| |
| /** |
| * The seed increment. |
| */ |
| private static final long GAMMA = 0x9e3779b97f4a7c15L; |
| |
| /** |
| * The increment for generating probe values. |
| */ |
| private static final int PROBE_INCREMENT = 0x9e3779b9; |
| |
| /** |
| * The increment of seeder per new instance. |
| */ |
| private static final long SEEDER_INCREMENT = 0xbb67ae8584caa73bL; |
| |
| // Constants from SplittableRandom |
| private static final double DOUBLE_UNIT = 0x1.0p-53; // 1.0 / (1L << 53) |
| private static final float FLOAT_UNIT = 0x1.0p-24f; // 1.0f / (1 << 24) |
| |
| // IllegalArgumentException messages |
| static final String BAD_BOUND = "bound must be positive"; |
| static final String BAD_RANGE = "bound must be greater than origin"; |
| static final String BAD_SIZE = "size must be non-negative"; |
| |
| // Unsafe mechanics |
| private static final sun.misc.Unsafe U = sun.misc.Unsafe.getUnsafe(); |
| private static final long SEED; |
| private static final long PROBE; |
| private static final long SECONDARY; |
| static { |
| try { |
| SEED = U.objectFieldOffset |
| (Thread.class.getDeclaredField("threadLocalRandomSeed")); |
| PROBE = U.objectFieldOffset |
| (Thread.class.getDeclaredField("threadLocalRandomProbe")); |
| SECONDARY = U.objectFieldOffset |
| (Thread.class.getDeclaredField("threadLocalRandomSecondarySeed")); |
| } catch (ReflectiveOperationException e) { |
| throw new Error(e); |
| } |
| } |
| |
| /** Rarely-used holder for the second of a pair of Gaussians */ |
| private static final ThreadLocal<Double> nextLocalGaussian = |
| new ThreadLocal<>(); |
| |
| /** Generates per-thread initialization/probe field */ |
| private static final AtomicInteger probeGenerator = new AtomicInteger(); |
| |
| /** The common ThreadLocalRandom */ |
| static final ThreadLocalRandom instance = new ThreadLocalRandom(); |
| |
| /** |
| * The next seed for default constructors. |
| */ |
| private static final AtomicLong seeder |
| = new AtomicLong(mix64(System.currentTimeMillis()) ^ |
| mix64(System.nanoTime())); |
| |
| // at end of <clinit> to survive static initialization circularity |
| static { |
| if (java.security.AccessController.doPrivileged( |
| new java.security.PrivilegedAction<Boolean>() { |
| public Boolean run() { |
| return Boolean.getBoolean("java.util.secureRandomSeed"); |
| }})) { |
| byte[] seedBytes = java.security.SecureRandom.getSeed(8); |
| long s = (long)seedBytes[0] & 0xffL; |
| for (int i = 1; i < 8; ++i) |
| s = (s << 8) | ((long)seedBytes[i] & 0xffL); |
| seeder.set(s); |
| } |
| } |
| } |
