--- jsr166/src/main/java/util/SplittableRandom.java 2013/10/07 10:54:27 1.24
+++ jsr166/src/main/java/util/SplittableRandom.java 2016/11/12 03:15:13 1.34
@@ -25,15 +25,14 @@
package java.util;
-import java.net.NetworkInterface;
import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.DoubleConsumer;
import java.util.function.IntConsumer;
import java.util.function.LongConsumer;
-import java.util.function.DoubleConsumer;
-import java.util.stream.StreamSupport;
+import java.util.stream.DoubleStream;
import java.util.stream.IntStream;
import java.util.stream.LongStream;
-import java.util.stream.DoubleStream;
+import java.util.stream.StreamSupport;
/**
* A generator of uniform pseudorandom values applicable for use in
@@ -53,15 +52,15 @@ import java.util.stream.DoubleStream;
* types and ranges, but similar properties are expected to hold, at
* least approximately, for others as well. The period
* (length of any series of generated values before it repeats) is at
- * least 264.
+ * least 264.
*
- * Method {@link #split} constructs and returns a new
+ * Method {@link #split} constructs and returns a new
* SplittableRandom instance that shares no mutable state with the
* current instance. However, with very high probability, the
* values collectively generated by the two objects have the same
* statistical properties as if the same quantity of values were
* generated by a single thread using a single {@code
- * SplittableRandom} object.
+ * SplittableRandom} object.
*
* Instances of SplittableRandom are not thread-safe.
* They are designed to be split, not shared, across threads. For
@@ -72,7 +71,7 @@ import java.util.stream.DoubleStream;
*
* This class provides additional methods for generating random
* streams, that employ the above techniques when used in {@code
- * stream.parallel()} mode.
+ * stream.parallel()} mode.
*
*
*
@@ -140,11 +139,10 @@ public final class SplittableRandom {
* other cases, this split must be performed in a thread-safe
* manner, so we use an AtomicLong to represent the seed rather
* than use an explicit SplittableRandom. To bootstrap the
- * defaultGen, we start off using a seed based on current time and
- * network interface address 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.
+ * 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.
*
* It is a relatively simple matter to apply the basic design here
* to use 128 bit seeds. However, emulating 128bit arithmetic and
@@ -221,58 +219,33 @@ public final class SplittableRandom {
return seed += gamma;
}
+ // 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";
+
/**
* The seed generator for default constructors.
*/
- private static final AtomicLong defaultGen = new AtomicLong(initialSeed());
-
- private static long initialSeed() {
- String pp = java.security.AccessController.doPrivileged(
- new sun.security.action.GetPropertyAction(
- "java.util.secureRandomSeed"));
- if (pp != null && pp.equalsIgnoreCase("true")) {
+ private static final AtomicLong defaultGen
+ = new AtomicLong(mix64(System.currentTimeMillis()) ^
+ mix64(System.nanoTime()));
+
+ // at end of to survive static initialization circularity
+ static {
+ if (java.security.AccessController.doPrivileged(
+ new java.security.PrivilegedAction() {
+ public Boolean run() {
+ return Boolean.getBoolean("java.util.secureRandomSeed");
+ }})) {
byte[] seedBytes = java.security.SecureRandom.getSeed(8);
- long s = (long)(seedBytes[0]) & 0xffL;
+ long s = (long)seedBytes[0] & 0xffL;
for (int i = 1; i < 8; ++i)
- s = (s << 8) | ((long)(seedBytes[i]) & 0xffL);
- return s;
+ s = (s << 8) | ((long)seedBytes[i] & 0xffL);
+ defaultGen.set(s);
}
- long h = 0L;
- try {
- Enumeration ifcs =
- NetworkInterface.getNetworkInterfaces();
- boolean retry = false; // retry once if getHardwareAddress is null
- while (ifcs.hasMoreElements()) {
- NetworkInterface ifc = ifcs.nextElement();
- if (!ifc.isVirtual()) { // skip fake addresses
- byte[] bs = ifc.getHardwareAddress();
- if (bs != null) {
- int n = bs.length;
- int m = Math.min(n >>> 1, 4);
- for (int i = 0; i < m; ++i)
- h = (h << 16) ^ (bs[i] << 8) ^ bs[n-1-i];
- if (m < 4)
- h = (h << 8) ^ bs[n-1-m];
- h = mix64(h);
- break;
- }
- else if (!retry)
- retry = true;
- else
- break;
- }
- }
- } catch (Exception ignore) {
- }
- return (h ^ mix64(System.currentTimeMillis()) ^
- mix64(System.nanoTime()));
}
- // 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";
-
/*
* Internal versions of nextX methods used by streams, as well as
* the public nextX(origin, bound) methods. These exist mainly to
@@ -445,7 +418,7 @@ public final class SplittableRandom {
*/
public int nextInt(int bound) {
if (bound <= 0)
- throw new IllegalArgumentException(BadBound);
+ throw new IllegalArgumentException(BAD_BOUND);
// Specialize internalNextInt for origin 0
int r = mix32(nextSeed());
int m = bound - 1;
@@ -473,7 +446,7 @@ public final class SplittableRandom {
*/
public int nextInt(int origin, int bound) {
if (origin >= bound)
- throw new IllegalArgumentException(BadRange);
+ throw new IllegalArgumentException(BAD_RANGE);
return internalNextInt(origin, bound);
}
@@ -497,7 +470,7 @@ public final class SplittableRandom {
*/
public long nextLong(long bound) {
if (bound <= 0)
- throw new IllegalArgumentException(BadBound);
+ throw new IllegalArgumentException(BAD_BOUND);
// Specialize internalNextLong for origin 0
long r = mix64(nextSeed());
long m = bound - 1;
@@ -525,7 +498,7 @@ public final class SplittableRandom {
*/
public long nextLong(long origin, long bound) {
if (origin >= bound)
- throw new IllegalArgumentException(BadRange);
+ throw new IllegalArgumentException(BAD_RANGE);
return internalNextLong(origin, bound);
}
@@ -551,13 +524,27 @@ public final class SplittableRandom {
*/
public double nextDouble(double bound) {
if (!(bound > 0.0))
- throw new IllegalArgumentException(BadBound);
+ 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);
}
/**
+ * Generates a pseudorandom number with the indicated number of
+ * bits. Unlike in superclass @{link Random}, this method is never
+ * internally called or used by any other publicly accessible
+ * method.
+ *
+ * @param bits random bits
+ * @return the next pseudorandom value from this random number
+ * generator's sequence
+ */
+ protected int next(int bits) {
+ return (int)(nextLong() >>> (64 - bits));
+ }
+
+ /**
* Returns a pseudorandom {@code double} value between the specified
* origin (inclusive) and bound (exclusive).
*
@@ -570,7 +557,7 @@ public final class SplittableRandom {
*/
public double nextDouble(double origin, double bound) {
if (!(origin < bound))
- throw new IllegalArgumentException(BadRange);
+ throw new IllegalArgumentException(BAD_RANGE);
return internalNextDouble(origin, bound);
}
@@ -598,7 +585,7 @@ public final class SplittableRandom {
*/
public IntStream ints(long streamSize) {
if (streamSize < 0L)
- throw new IllegalArgumentException(BadSize);
+ throw new IllegalArgumentException(BAD_SIZE);
return StreamSupport.intStream
(new RandomIntsSpliterator
(this, 0L, streamSize, Integer.MAX_VALUE, 0),
@@ -639,9 +626,9 @@ public final class SplittableRandom {
public IntStream ints(long streamSize, int randomNumberOrigin,
int randomNumberBound) {
if (streamSize < 0L)
- throw new IllegalArgumentException(BadSize);
+ throw new IllegalArgumentException(BAD_SIZE);
if (randomNumberOrigin >= randomNumberBound)
- throw new IllegalArgumentException(BadRange);
+ throw new IllegalArgumentException(BAD_RANGE);
return StreamSupport.intStream
(new RandomIntsSpliterator
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
@@ -665,7 +652,7 @@ public final class SplittableRandom {
*/
public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
if (randomNumberOrigin >= randomNumberBound)
- throw new IllegalArgumentException(BadRange);
+ throw new IllegalArgumentException(BAD_RANGE);
return StreamSupport.intStream
(new RandomIntsSpliterator
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
@@ -684,7 +671,7 @@ public final class SplittableRandom {
*/
public LongStream longs(long streamSize) {
if (streamSize < 0L)
- throw new IllegalArgumentException(BadSize);
+ throw new IllegalArgumentException(BAD_SIZE);
return StreamSupport.longStream
(new RandomLongsSpliterator
(this, 0L, streamSize, Long.MAX_VALUE, 0L),
@@ -725,9 +712,9 @@ public final class SplittableRandom {
public LongStream longs(long streamSize, long randomNumberOrigin,
long randomNumberBound) {
if (streamSize < 0L)
- throw new IllegalArgumentException(BadSize);
+ throw new IllegalArgumentException(BAD_SIZE);
if (randomNumberOrigin >= randomNumberBound)
- throw new IllegalArgumentException(BadRange);
+ throw new IllegalArgumentException(BAD_RANGE);
return StreamSupport.longStream
(new RandomLongsSpliterator
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
@@ -751,7 +738,7 @@ public final class SplittableRandom {
*/
public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
if (randomNumberOrigin >= randomNumberBound)
- throw new IllegalArgumentException(BadRange);
+ throw new IllegalArgumentException(BAD_RANGE);
return StreamSupport.longStream
(new RandomLongsSpliterator
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
@@ -770,7 +757,7 @@ public final class SplittableRandom {
*/
public DoubleStream doubles(long streamSize) {
if (streamSize < 0L)
- throw new IllegalArgumentException(BadSize);
+ throw new IllegalArgumentException(BAD_SIZE);
return StreamSupport.doubleStream
(new RandomDoublesSpliterator
(this, 0L, streamSize, Double.MAX_VALUE, 0.0),
@@ -813,9 +800,9 @@ public final class SplittableRandom {
public DoubleStream doubles(long streamSize, double randomNumberOrigin,
double randomNumberBound) {
if (streamSize < 0L)
- throw new IllegalArgumentException(BadSize);
+ throw new IllegalArgumentException(BAD_SIZE);
if (!(randomNumberOrigin < randomNumberBound))
- throw new IllegalArgumentException(BadRange);
+ throw new IllegalArgumentException(BAD_RANGE);
return StreamSupport.doubleStream
(new RandomDoublesSpliterator
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound),
@@ -839,7 +826,7 @@ public final class SplittableRandom {
*/
public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
if (!(randomNumberOrigin < randomNumberBound))
- throw new IllegalArgumentException(BadRange);
+ throw new IllegalArgumentException(BAD_RANGE);
return StreamSupport.doubleStream
(new RandomDoublesSpliterator
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
@@ -854,7 +841,8 @@ public final class SplittableRandom {
* approach. The long and double versions of this class are
* identical except for types.
*/
- static final class RandomIntsSpliterator implements Spliterator.OfInt {
+ private static final class RandomIntsSpliterator
+ implements Spliterator.OfInt {
final SplittableRandom rng;
long index;
final long fence;
@@ -909,7 +897,8 @@ public final class SplittableRandom {
/**
* Spliterator for long streams.
*/
- static final class RandomLongsSpliterator implements Spliterator.OfLong {
+ private static final class RandomLongsSpliterator
+ implements Spliterator.OfLong {
final SplittableRandom rng;
long index;
final long fence;
@@ -965,7 +954,8 @@ public final class SplittableRandom {
/**
* Spliterator for double streams.
*/
- static final class RandomDoublesSpliterator implements Spliterator.OfDouble {
+ private static final class RandomDoublesSpliterator
+ implements Spliterator.OfDouble {
final SplittableRandom rng;
long index;
final long fence;