archive/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2025-08-28 07:14:30 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

8248862: Implement Enhanced Pseudo-Random Number Generators

Browse source 
Reviewed-by: darcy
This commit is contained in:
Jim Laskey 2021-04-05 16:29:18 +00:00
parent 39719da9d1
commit a0ec2cb289
27 changed files with 11384 additions and 1772 deletions
Download patch file Download diff file Expand all files Collapse all files

669
src/java.base/share/classes/java/util/Random.java
View file

@ -24,21 +24,26 @@
*/
package java.util;
import java.io.*;
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;
import jdk.internal.util.random.RandomSupport.AbstractSpliteratorGenerator;
import jdk.internal.util.random.RandomSupport.RandomGeneratorProperties;
import jdk.internal.util.random.RandomSupport.RandomIntsSpliterator;
import jdk.internal.util.random.RandomSupport.RandomLongsSpliterator;
import jdk.internal.util.random.RandomSupport.RandomDoublesSpliterator;
import static jdk.internal.util.random.RandomSupport.*;
import jdk.internal.misc.Unsafe;
/**
* An instance of this class is used to generate a stream of
* pseudorandom numbers. The class uses a 48-bit seed, which is
* pseudorandom numbers; its period is only 2<sup>48</sup>.
* The class uses a 48-bit seed, which is
* modified using a linear congruential formula. (See Donald E. Knuth,
* <cite>The Art of Computer Programming, Volume 2, Third
* edition: Seminumerical Algorithms</cite>, Section 3.2.1.)
@ -74,7 +79,14 @@ import jdk.internal.misc.Unsafe;
* @author Frank Yellin
* @since 1.0
*/
public class Random implements java.io.Serializable {
@SuppressWarnings("exports")
@RandomGeneratorProperties(
name = "Random",
i = 48, j = 0, k = 0,
equidistribution = 0
)
public class Random extends AbstractSpliteratorGenerator
implements java.io.Serializable {
/** use serialVersionUID from JDK 1.1 for interoperability */
@java.io.Serial
static final long serialVersionUID = 3905348978240129619L;
@ -92,11 +104,6 @@ public class Random implements java.io.Serializable {
private static final double DOUBLE_UNIT = 0x1.0p-53; // 1.0 / (1L << 53)
// IllegalArgumentException messages
static final String BadBound = "bound must be positive";
static final String BadRange = "bound must be greater than origin";
static final String BadSize = "size must be non-negative";
/**
* Creates a new random number generator. This constructor sets
* the seed of the random number generator to a value very likely
@ -118,17 +125,18 @@ public class Random implements java.io.Serializable {
}
private static final AtomicLong seedUniquifier
= new AtomicLong(8682522807148012L);
= new AtomicLong(8682522807148012L);
/**
* Creates a new random number generator using a single {@code long} seed.
* The seed is the initial value of the internal state of the pseudorandom
* number generator which is maintained by method {@link #next}.
*
* <p>The invocation {@code new Random(seed)} is equivalent to:
* <pre> {@code
* @implSpec The invocation {@code new Random(seed)} is equivalent to:
* <pre>{@code
* Random rnd = new Random();
* rnd.setSeed(seed);}</pre>
* rnd.setSeed(seed);
* }</pre>
*
* @param seed the initial seed
* @see #setSeed(long)
@ -211,9 +219,9 @@ public class Random implements java.io.Serializable {
* byte array. The number of random bytes produced is equal to
* the length of the byte array.
*
* <p>The method {@code nextBytes} is implemented by class {@code Random}
* as if by:
* <pre> {@code
* @implSpec The method {@code nextBytes} is
* implemented by class {@code Random} as if by:
* <pre>{@code
* public void nextBytes(byte[] bytes) {
* for (int i = 0; i < bytes.length; )
* for (int rnd = nextInt(), n = Math.min(bytes.length - i, 4);
@ -225,90 +233,15 @@ public class Random implements java.io.Serializable {
* @throws NullPointerException if the byte array is null
* @since 1.1
*/
@Override
public void nextBytes(byte[] bytes) {
for (int i = 0, len = bytes.length; i < len; )
for (int rnd = nextInt(),
n = Math.min(len - i, Integer.SIZE/Byte.SIZE);
n = Math.min(len - i, Integer.SIZE/Byte.SIZE);
n-- > 0; rnd >>= Byte.SIZE)
bytes[i++] = (byte)rnd;
}
/**
* 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 = nextLong();
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 = nextLong() >>> 1) // retry
;
r += origin;
}
else { // range not representable as long
while (r < origin || r >= bound)
r = nextLong();
}
}
return r;
}
/**
* The form of nextInt used by IntStream Spliterators.
* For the unbounded case: uses nextInt().
* For the bounded case with representable range: uses nextInt(int bound)
* For the bounded case with unrepresentable range: uses nextInt()
*
* @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) {
if (origin < bound) {
int n = bound - origin;
if (n > 0) {
return nextInt(n) + origin;
}
else { // range not representable as int
int r;
do {
r = nextInt();
} while (r < origin || r >= bound);
return r;
}
}
else {
return nextInt();
}
}
/**
* 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 = nextDouble();
if (origin < bound) {
r = r * (bound - origin) + origin;
if (r >= bound) // correct for rounding
r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
}
return r;
}
/**
* Returns the next pseudorandom, uniformly distributed {@code int}
* value from this random number generator's sequence. The general
@ -316,9 +249,9 @@ public class Random implements java.io.Serializable {
* pseudorandomly generated and returned. All 2<sup>32</sup> possible
* {@code int} values are produced with (approximately) equal probability.
*
* <p>The method {@code nextInt} is implemented by class {@code Random}
* as if by:
* <pre> {@code
* @implSpec The method {@code nextInt} is
* implemented by class {@code Random} as if by:
* <pre>{@code
* public int nextInt() {
* return next(32);
* }}</pre>
@ -326,6 +259,7 @@ public class Random implements java.io.Serializable {
* @return the next pseudorandom, uniformly distributed {@code int}
* value from this random number generator's sequence
*/
@Override
public int nextInt() {
return next(32);
}
@ -337,9 +271,11 @@ public class Random implements java.io.Serializable {
* {@code nextInt} is that one {@code int} value in the specified range
* is pseudorandomly generated and returned. All {@code bound} possible
* {@code int} values are produced with (approximately) equal
* probability. The method {@code nextInt(int bound)} is implemented by
* probability.
*
* @implSpec The method {@code nextInt(int bound)} is implemented by
* class {@code Random} as if by:
* <pre> {@code
* <pre>{@code
* public int nextInt(int bound) {
* if (bound <= 0)
* throw new IllegalArgumentException("bound must be positive");
@ -384,15 +320,15 @@ public class Random implements java.io.Serializable {
* @throws IllegalArgumentException if bound is not positive
* @since 1.2
*/
@Override
public int nextInt(int bound) {
if (bound <= 0)
throw new IllegalArgumentException(BadBound);
throw new IllegalArgumentException(BAD_BOUND);
int r = next(31);
int m = bound - 1;
if ((bound & m) == 0) // i.e., bound is a power of 2
r = (int)((bound * (long)r) >> 31);
else {
else { // reject over-represented candidates
for (int u = r;
u - (r = u % bound) + m < 0;
u = next(31))
@ -400,16 +336,15 @@ public class Random implements java.io.Serializable {
}
return r;
}
/**
* Returns the next pseudorandom, uniformly distributed {@code long}
* value from this random number generator's sequence. The general
* contract of {@code nextLong} is that one {@code long} value is
* pseudorandomly generated and returned.
*
* <p>The method {@code nextLong} is implemented by class {@code Random}
* @implSpec The method {@code nextLong} is implemented by class {@code Random}
* as if by:
* <pre> {@code
* <pre>{@code
* public long nextLong() {
* return ((long)next(32) << 32) + next(32);
* }}</pre>
@ -420,6 +355,7 @@ public class Random implements java.io.Serializable {
* @return the next pseudorandom, uniformly distributed {@code long}
* value from this random number generator's sequence
*/
@Override
public long nextLong() {
// it's okay that the bottom word remains signed.
return ((long)(next(32)) << 32) + next(32);
@ -433,9 +369,9 @@ public class Random implements java.io.Serializable {
* values {@code true} and {@code false} are produced with
* (approximately) equal probability.
*
* <p>The method {@code nextBoolean} is implemented by class {@code Random}
* as if by:
* <pre> {@code
* @implSpec The method {@code nextBoolean} is implemented by class
* {@code Random} as if by:
* <pre>{@code
* public boolean nextBoolean() {
* return next(1) != 0;
* }}</pre>
@ -445,6 +381,7 @@ public class Random implements java.io.Serializable {
* sequence
* @since 1.2
*/
@Override
public boolean nextBoolean() {
return next(1) != 0;
}
@ -462,21 +399,19 @@ public class Random implements java.io.Serializable {
* where <i>m</i> is a positive integer less than 2<sup>24</sup>, are
* produced with (approximately) equal probability.
*
* <p>The method {@code nextFloat} is implemented by class {@code Random}
* as if by:
* <pre> {@code
* @implSpec The method {@code nextFloat} is implemented by class
* {@code Random} as if by:
* <pre>{@code
* public float nextFloat() {
* return next(24) / ((float)(1 << 24));
* }}</pre>
*
* <p>The hedge "approximately" is used in the foregoing description only
* because the next method is only approximately an unbiased source of
* independently chosen bits. If it were a perfect source of randomly
* chosen bits, then the algorithm shown would choose {@code float}
* values from the stated range with perfect uniformity.<p>
* [In early versions of Java, the result was incorrectly calculated as:
* <pre> {@code
* return next(30) / ((float)(1 << 30));}</pre>
* <pre> {@code return next(30) / ((float)(1 << 30));}</pre>
* This might seem to be equivalent, if not better, but in fact it
* introduced a slight nonuniformity because of the bias in the rounding
* of floating-point numbers: it was slightly more likely that the
@ -486,6 +421,7 @@ public class Random implements java.io.Serializable {
* value between {@code 0.0} and {@code 1.0} from this
* random number generator's sequence
*/
@Override
public float nextFloat() {
return next(24) / ((float)(1 << 24));
}
@ -500,35 +436,33 @@ public class Random implements java.io.Serializable {
* range {@code 0.0d} (inclusive) to {@code 1.0d} (exclusive), is
* pseudorandomly generated and returned.
*
* <p>The method {@code nextDouble} is implemented by class {@code Random}
* as if by:
* <pre> {@code
* @implSpec The method {@code nextDouble} is implemented by class
* {@code Random} as if by:
* <pre>{@code
* public double nextDouble() {
* return (((long)next(26) << 27) + next(27))
* / (double)(1L << 53);
* }}</pre>
*
* <p>The hedge "approximately" is used in the foregoing description only
* because the {@code next} method is only approximately an unbiased
* source of independently chosen bits. If it were a perfect source of
* randomly chosen bits, then the algorithm shown would choose
* {@code double} values from the stated range with perfect uniformity.
* because the {@code next} method is only approximately an unbiased source
* of independently chosen bits. If it were a perfect source of randomly
* chosen bits, then the algorithm shown would choose {@code double} values
* from the stated range with perfect uniformity.
* <p>[In early versions of Java, the result was incorrectly calculated as:
* <pre> {@code
* return (((long)next(27) << 27) + next(27))
* / (double)(1L << 54);}</pre>
* <pre> {@code return (((long)next(27) << 27) + next(27)) / (double)(1L << 54);}</pre>
* This might seem to be equivalent, if not better, but in fact it
* introduced a large nonuniformity because of the bias in the rounding
* of floating-point numbers: it was three times as likely that the
* low-order bit of the significand would be 0 than that it would be 1!
* This nonuniformity probably doesn't matter much in practice, but we
* strive for perfection.]
* introduced a large nonuniformity because of the bias in the rounding of
* floating-point numbers: it was three times as likely that the low-order
* bit of the significand would be 0 than that it would be 1! This
* nonuniformity probably doesn't matter much in practice, but we strive
* for perfection.]
*
* @return the next pseudorandom, uniformly distributed {@code double}
* value between {@code 0.0} and {@code 1.0} from this
* random number generator's sequence
* @see Math#random
*/
@Override
public double nextDouble() {
return (((long)(next(26)) << 27) + next(27)) * DOUBLE_UNIT;
}
@ -546,9 +480,9 @@ public class Random implements java.io.Serializable {
* normal distribution with mean {@code 0.0} and standard deviation
* {@code 1.0}, is pseudorandomly generated and returned.
*
* <p>The method {@code nextGaussian} is implemented by class
* @implSpec The method {@code nextGaussian} is implemented by class
* {@code Random} as if by a threadsafe version of the following:
* <pre> {@code
* <pre>{@code
* private double nextNextGaussian;
* private boolean haveNextNextGaussian = false;
*
@ -569,6 +503,7 @@ public class Random implements java.io.Serializable {
* return v1 * multiplier;
* }
* }}</pre>
*
* This uses the <i>polar method</i> of G. E. P. Box, M. E. Muller, and
* G. Marsaglia, as described by Donald E. Knuth in <cite>The Art of
* Computer Programming, Volume 2, third edition: Seminumerical Algorithms</cite>,
@ -581,6 +516,7 @@ public class Random implements java.io.Serializable {
* standard deviation {@code 1.0} from this random number
* generator's sequence
*/
@Override
public synchronized double nextGaussian() {
// See Knuth, TAOCP, Vol. 2, 3rd edition, Section 3.4.1 Algorithm C.
if (haveNextNextGaussian) {
@ -600,8 +536,110 @@ public class Random implements java.io.Serializable {
}
}
// stream methods, coded in a way intended to better isolate for
// maintenance purposes the small differences across forms.
/**
* Serializable fields for Random.
*
* @serialField seed long
* seed for random computations
* @serialField nextNextGaussian double
* next Gaussian to be returned
* @serialField haveNextNextGaussian boolean
* nextNextGaussian is valid
*/
@java.io.Serial
private static final ObjectStreamField[] serialPersistentFields = {
new ObjectStreamField("seed", Long.TYPE),
new ObjectStreamField("nextNextGaussian", Double.TYPE),
new ObjectStreamField("haveNextNextGaussian", Boolean.TYPE)
};
/**
* Reconstitute the {@code Random} instance from a stream (that is,
* deserialize it).
*
* @param s the {@code ObjectInputStream} from which data is read
*
* @throws IOException if an I/O error occurs
* @throws ClassNotFoundException if a serialized class cannot be loaded
*/
@java.io.Serial
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
ObjectInputStream.GetField fields = s.readFields();
// The seed is read in as {@code long} for
// historical reasons, but it is converted to an AtomicLong.
long seedVal = fields.get("seed", -1L);
if (seedVal < 0)
throw new java.io.StreamCorruptedException(
"Random: invalid seed");
resetSeed(seedVal);
nextNextGaussian = fields.get("nextNextGaussian", 0.0);
haveNextNextGaussian = fields.get("haveNextNextGaussian", false);
}
/**
* Save the {@code Random} instance to a stream.
*
* @param s the {@code ObjectOutputStream} to which data is written
*
* @throws IOException if an I/O error occurs
*/
@java.io.Serial
private synchronized void writeObject(ObjectOutputStream s)
throws IOException {
// set the values of the Serializable fields
ObjectOutputStream.PutField fields = s.putFields();
// The seed is serialized as a long for historical reasons.
fields.put("seed", seed.get());
fields.put("nextNextGaussian", nextNextGaussian);
fields.put("haveNextNextGaussian", haveNextNextGaussian);
// save them
s.writeFields();
}
// Support for resetting seed while deserializing
private static final Unsafe unsafe = Unsafe.getUnsafe();
private static final long seedOffset;
static {
try {
seedOffset = unsafe.objectFieldOffset
(Random.class.getDeclaredField("seed"));
} catch (Exception ex) { throw new Error(ex); }
}
private void resetSeed(long seedVal) {
unsafe.putReferenceVolatile(this, seedOffset, new AtomicLong(seedVal));
}
// Methods required by class AbstractSpliteratorGenerator
/**
* @hidden
*/
@Override
public Spliterator.OfInt makeIntsSpliterator(long index, long fence, int origin, int bound) {
return new RandomIntsSpliterator(this, index, fence, origin, bound);
}
/**
* @hidden
*/
@Override
public Spliterator.OfLong makeLongsSpliterator(long index, long fence, long origin, long bound) {
return new RandomLongsSpliterator(this, index, fence, origin, bound);
}
/**
* @hidden
*/
@Override
public Spliterator.OfDouble makeDoublesSpliterator(long index, long fence, double origin, double bound) {
return new RandomDoublesSpliterator(this, index, fence, origin, bound);
}
/**
* Returns a stream producing the given {@code streamSize} number of
@ -616,13 +654,9 @@ public class Random implements java.io.Serializable {
* less than zero
* @since 1.8
*/
@Override
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);
return super.ints(streamSize);
}
/**
@ -638,11 +672,9 @@ public class Random implements java.io.Serializable {
* @return a stream of pseudorandom {@code int} values
* @since 1.8
*/
@Override
public IntStream ints() {
return StreamSupport.intStream
(new RandomIntsSpliterator
(this, 0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0),
false);
return super.ints();
}
/**
@ -677,16 +709,9 @@ public class Random implements java.io.Serializable {
* 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(BadSize);
if (randomNumberOrigin >= randomNumberBound)
throw new IllegalArgumentException(BadRange);
return StreamSupport.intStream
(new RandomIntsSpliterator
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
false);
@Override
public IntStream ints(long streamSize, int randomNumberOrigin, int randomNumberBound) {
return super.ints(streamSize, randomNumberOrigin, randomNumberBound);
}
/**
@ -722,13 +747,9 @@ public class Random implements java.io.Serializable {
* is greater than or equal to {@code randomNumberBound}
* @since 1.8
*/
@Override
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);
return super.ints(randomNumberOrigin, randomNumberBound);
}
/**
@ -744,13 +765,9 @@ public class Random implements java.io.Serializable {
* less than zero
* @since 1.8
*/
@Override
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);
return super.longs(streamSize);
}
/**
@ -766,11 +783,9 @@ public class Random implements java.io.Serializable {
* @return a stream of pseudorandom {@code long} values
* @since 1.8
*/
@Override
public LongStream longs() {
return StreamSupport.longStream
(new RandomLongsSpliterator
(this, 0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L),
false);
return super.longs();
}
/**
@ -810,16 +825,9 @@ public class Random implements java.io.Serializable {
* 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(BadSize);
if (randomNumberOrigin >= randomNumberBound)
throw new IllegalArgumentException(BadRange);
return StreamSupport.longStream
(new RandomLongsSpliterator
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
false);
@Override
public LongStream longs(long streamSize, long randomNumberOrigin, long randomNumberBound) {
return super.longs(streamSize, randomNumberOrigin, randomNumberBound);
}
/**
@ -860,13 +868,9 @@ public class Random implements java.io.Serializable {
* is greater than or equal to {@code randomNumberBound}
* @since 1.8
*/
@Override
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);
return super.longs(randomNumberOrigin, randomNumberBound);
}
/**
@ -883,13 +887,9 @@ public class Random implements java.io.Serializable {
* less than zero
* @since 1.8
*/
@Override
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);
return super.doubles(streamSize);
}
/**
@ -906,14 +906,12 @@ public class Random implements java.io.Serializable {
* @return a stream of pseudorandom {@code double} values
* @since 1.8
*/
@Override
public DoubleStream doubles() {
return StreamSupport.doubleStream
(new RandomDoublesSpliterator
(this, 0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0),
false);
return super.doubles();
}
/**
/**
* Returns a stream producing the given {@code streamSize} number of
* pseudorandom {@code double} values, each conforming to the given origin
* (inclusive) and bound (exclusive).
@ -934,22 +932,15 @@ public class Random implements java.io.Serializable {
* @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}
* @throws IllegalArgumentException if {@code streamSize} is less than zero,
* or {@code randomNumberOrigin} is not finite,
* or {@code randomNumberBound} is not finite, or {@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(BadSize);
if (!(randomNumberOrigin < randomNumberBound))
throw new IllegalArgumentException(BadRange);
return StreamSupport.doubleStream
(new RandomDoublesSpliterator
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
false);
@Override
public DoubleStream doubles(long streamSize, double randomNumberOrigin, double randomNumberBound) {
return super.doubles(streamSize, randomNumberOrigin, randomNumberBound);
}
/**
@ -979,260 +970,8 @@ public class Random implements java.io.Serializable {
* is greater than or equal to {@code randomNumberBound}
* @since 1.8
*/
@Override
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 Random rng;
long index;
final long fence;
final int origin;
final int bound;
RandomIntsSpliterator(Random 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, 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;
Random 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 Random rng;
long index;
final long fence;
final long origin;
final long bound;
RandomLongsSpliterator(Random 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, 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;
Random 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 Random rng;
long index;
final long fence;
final double origin;
final double bound;
RandomDoublesSpliterator(Random 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, 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;
Random r = rng;
double o = origin, b = bound;
do {
consumer.accept(r.internalNextDouble(o, b));
} while (++i < f);
}
}
}
/**
* Serializable fields for Random.
*
* @serialField seed long
* seed for random computations
* @serialField nextNextGaussian double
* next Gaussian to be returned
* @serialField haveNextNextGaussian boolean
* nextNextGaussian is valid
*/
@java.io.Serial
private static final ObjectStreamField[] serialPersistentFields = {
new ObjectStreamField("seed", Long.TYPE),
new ObjectStreamField("nextNextGaussian", Double.TYPE),
new ObjectStreamField("haveNextNextGaussian", Boolean.TYPE)
};
/**
* Reconstitute the {@code Random} instance from a stream (that is,
* deserialize it).
*
* @param s the {@code ObjectInputStream} from which data is read
* @throws IOException if an I/O error occurs
* @throws ClassNotFoundException if a serialized class cannot be loaded
*/
@java.io.Serial
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
ObjectInputStream.GetField fields = s.readFields();
// The seed is read in as {@code long} for
// historical reasons, but it is converted to an AtomicLong.
long seedVal = fields.get("seed", -1L);
if (seedVal < 0)
throw new java.io.StreamCorruptedException(
"Random: invalid seed");
resetSeed(seedVal);
nextNextGaussian = fields.get("nextNextGaussian", 0.0);
haveNextNextGaussian = fields.get("haveNextNextGaussian", false);
}
/**
* Save the {@code Random} instance to a stream.
*
* @param s the {@code ObjectOutputStream} to which data is written
* @throws IOException if an I/O error occurs
*/
@java.io.Serial
private synchronized void writeObject(ObjectOutputStream s)
throws IOException {
// set the values of the Serializable fields
ObjectOutputStream.PutField fields = s.putFields();
// The seed is serialized as a long for historical reasons.
fields.put("seed", seed.get());
fields.put("nextNextGaussian", nextNextGaussian);
fields.put("haveNextNextGaussian", haveNextNextGaussian);
// save them
s.writeFields();
}
// Support for resetting seed while deserializing
private static final Unsafe unsafe = Unsafe.getUnsafe();
private static final long seedOffset;
static {
try {
seedOffset = unsafe.objectFieldOffset
(Random.class.getDeclaredField("seed"));
} catch (Exception ex) { throw new Error(ex); }
}
private void resetSeed(long seedVal) {
unsafe.putReferenceVolatile(this, seedOffset, new AtomicLong(seedVal));
return super.doubles(randomNumberOrigin, randomNumberBound);
}
}