25 |
|
|
26 |
|
package java.util; |
27 |
|
|
28 |
– |
import java.net.NetworkInterface; |
28 |
|
import java.util.concurrent.atomic.AtomicLong; |
29 |
+ |
import java.util.function.DoubleConsumer; |
30 |
|
import java.util.function.IntConsumer; |
31 |
|
import java.util.function.LongConsumer; |
32 |
< |
import java.util.function.DoubleConsumer; |
33 |
< |
import java.util.stream.StreamSupport; |
32 |
> |
import java.util.stream.DoubleStream; |
33 |
|
import java.util.stream.IntStream; |
34 |
|
import java.util.stream.LongStream; |
35 |
< |
import java.util.stream.DoubleStream; |
35 |
> |
import java.util.stream.StreamSupport; |
36 |
|
|
37 |
|
/** |
38 |
|
* A generator of uniform pseudorandom values applicable for use in |
109 |
|
* For nextLong, the mix64 function is based on David Stafford's |
110 |
|
* (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html) |
111 |
|
* "Mix13" variant of the "64-bit finalizer" function in Austin |
112 |
< |
* Appleby's MurmurHash3 algorithm See |
113 |
< |
* http://code.google.com/p/smhasher/wiki/MurmurHash3 . The mix32 |
112 |
> |
* Appleby's MurmurHash3 algorithm (see |
113 |
> |
* http://code.google.com/p/smhasher/wiki/MurmurHash3). The mix32 |
114 |
|
* function is based on Stafford's Mix04 mix function, but returns |
115 |
|
* the upper 32 bits cast as int. |
116 |
|
* |
139 |
|
* other cases, this split must be performed in a thread-safe |
140 |
|
* manner, so we use an AtomicLong to represent the seed rather |
141 |
|
* than use an explicit SplittableRandom. To bootstrap the |
142 |
< |
* defaultGen, we start off using a seed based on current time and |
143 |
< |
* network interface address unless the java.util.secureRandomSeed |
144 |
< |
* property is set. This serves as a slimmed-down (and insecure) |
145 |
< |
* variant of SecureRandom that also avoids stalls that may occur |
147 |
< |
* when using /dev/random. |
142 |
> |
* defaultGen, we start off using a seed based on current time |
143 |
> |
* unless the java.util.secureRandomSeed property is set. This |
144 |
> |
* serves as a slimmed-down (and insecure) variant of SecureRandom |
145 |
> |
* that also avoids stalls that may occur when using /dev/random. |
146 |
|
* |
147 |
|
* It is a relatively simple matter to apply the basic design here |
148 |
|
* to use 128 bit seeds. However, emulating 128bit arithmetic and |
164 |
|
* The least non-zero value returned by nextDouble(). This value |
165 |
|
* is scaled by a random value of 53 bits to produce a result. |
166 |
|
*/ |
167 |
< |
private static final double DOUBLE_ULP = 1.0 / (1L << 53); |
167 |
> |
private static final double DOUBLE_UNIT = 0x1.0p-53; // 1.0 / (1L << 53); |
168 |
|
|
169 |
|
/** |
170 |
|
* The seed. Updated only via method nextSeed. |
188 |
|
* Computes Stafford variant 13 of 64bit mix function. |
189 |
|
*/ |
190 |
|
private static long mix64(long z) { |
191 |
< |
z *= 0xbf58476d1ce4e5b9L; |
192 |
< |
z = (z ^ (z >>> 32)) * 0x94d049bb133111ebL; |
193 |
< |
return z ^ (z >>> 32); |
191 |
> |
z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L; |
192 |
> |
z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL; |
193 |
> |
return z ^ (z >>> 31); |
194 |
|
} |
195 |
|
|
196 |
|
/** |
197 |
|
* Returns the 32 high bits of Stafford variant 4 mix64 function as int. |
198 |
|
*/ |
199 |
|
private static int mix32(long z) { |
200 |
< |
z *= 0x62a9d9ed799705f5L; |
200 |
> |
z = (z ^ (z >>> 33)) * 0x62a9d9ed799705f5L; |
201 |
|
return (int)(((z ^ (z >>> 28)) * 0xcb24d0a5c88c35b3L) >>> 32); |
202 |
|
} |
203 |
|
|
205 |
|
* Returns the gamma value to use for a new split instance. |
206 |
|
*/ |
207 |
|
private static long mixGamma(long z) { |
208 |
< |
z *= 0xff51afd7ed558ccdL; // MurmurHash3 mix constants |
208 |
> |
z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL; // MurmurHash3 mix constants |
209 |
|
z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L; |
210 |
|
z = (z ^ (z >>> 33)) | 1L; // force to be odd |
211 |
|
int n = Long.bitCount(z ^ (z >>> 1)); // ensure enough transitions |
235 |
|
s = (s << 8) | ((long)(seedBytes[i]) & 0xffL); |
236 |
|
return s; |
237 |
|
} |
238 |
< |
long h = 0L; |
241 |
< |
try { |
242 |
< |
Enumeration<NetworkInterface> ifcs = |
243 |
< |
NetworkInterface.getNetworkInterfaces(); |
244 |
< |
boolean retry = false; // retry once if getHardwareAddress is null |
245 |
< |
while (ifcs.hasMoreElements()) { |
246 |
< |
NetworkInterface ifc = ifcs.nextElement(); |
247 |
< |
if (!ifc.isVirtual()) { // skip fake addresses |
248 |
< |
byte[] bs = ifc.getHardwareAddress(); |
249 |
< |
if (bs != null) { |
250 |
< |
int n = bs.length; |
251 |
< |
int m = Math.min(n >>> 1, 4); |
252 |
< |
for (int i = 0; i < m; ++i) |
253 |
< |
h = (h << 16) ^ (bs[i] << 8) ^ bs[n-1-i]; |
254 |
< |
if (m < 4) |
255 |
< |
h = (h << 8) ^ bs[n-1-m]; |
256 |
< |
h = mix64(h); |
257 |
< |
break; |
258 |
< |
} |
259 |
< |
else if (!retry) |
260 |
< |
retry = true; |
261 |
< |
else |
262 |
< |
break; |
263 |
< |
} |
264 |
< |
} |
265 |
< |
} catch (Exception ignore) { |
266 |
< |
} |
267 |
< |
return (h ^ mix64(System.currentTimeMillis()) ^ |
238 |
> |
return (mix64(System.currentTimeMillis()) ^ |
239 |
|
mix64(System.nanoTime())); |
240 |
|
} |
241 |
|
|
344 |
|
* @return a pseudorandom value |
345 |
|
*/ |
346 |
|
final double internalNextDouble(double origin, double bound) { |
347 |
< |
double r = (nextLong() >>> 11) * DOUBLE_ULP; |
347 |
> |
double r = (nextLong() >>> 11) * DOUBLE_UNIT; |
348 |
|
if (origin < bound) { |
349 |
|
r = r * (bound - origin) + origin; |
350 |
|
if (r >= bound) // correct for rounding |
508 |
|
* (inclusive) and one (exclusive) |
509 |
|
*/ |
510 |
|
public double nextDouble() { |
511 |
< |
return (mix64(nextSeed()) >>> 11) * DOUBLE_ULP; |
511 |
> |
return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT; |
512 |
|
} |
513 |
|
|
514 |
|
/** |
523 |
|
public double nextDouble(double bound) { |
524 |
|
if (!(bound > 0.0)) |
525 |
|
throw new IllegalArgumentException(BadBound); |
526 |
< |
double result = (mix64(nextSeed()) >>> 11) * DOUBLE_ULP * bound; |
526 |
> |
double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound; |
527 |
|
return (result < bound) ? result : // correct for rounding |
528 |
|
Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
529 |
|
} |