| 8 |
|
package jsr166e.extra; |
| 9 |
|
import static java.lang.Double.doubleToRawLongBits; |
| 10 |
|
import static java.lang.Double.longBitsToDouble; |
| 11 |
– |
import sun.misc.Unsafe; |
| 11 |
|
|
| 12 |
|
/** |
| 13 |
|
* A {@code double} value that may be updated atomically. See the |
| 14 |
|
* {@link java.util.concurrent.atomic} package specification for |
| 15 |
|
* description of the properties of atomic variables. An {@code |
| 16 |
< |
* AtomicDouble} is used in applications such as atomic summation, and |
| 17 |
< |
* cannot be used as a replacement for a {@link Double}. However, |
| 16 |
> |
* AtomicDouble} is used in applications such as atomic accumulation, |
| 17 |
> |
* and cannot be used as a replacement for a {@link Double}. However, |
| 18 |
|
* this class does extend {@code Number} to allow uniform access by |
| 19 |
|
* tools and utilities that deal with numerically-based classes. |
| 20 |
|
* |
| 28 |
|
* long yBits = Double.doubleToRawLongBits(y); |
| 29 |
|
* return xBits == yBits; |
| 30 |
|
* }}</pre> |
| 31 |
< |
* |
| 33 |
< |
* @since 1.5 |
| 31 |
> |
* |
| 32 |
|
* @author Doug Lea |
| 33 |
|
* @author Martin Buchholz |
| 34 |
|
*/ |
| 35 |
|
public class AtomicDouble extends Number implements java.io.Serializable { |
| 36 |
< |
private static final long serialVersionUID = 1927816293512124184L; |
| 36 |
> |
static final long serialVersionUID = -8405198993435143622L; |
| 37 |
|
|
| 38 |
|
// setup to use Unsafe.compareAndSwapLong for updates |
| 39 |
< |
private static final Unsafe unsafe = Unsafe.getUnsafe(); |
| 39 |
> |
private static final sun.misc.Unsafe unsafe = getUnsafe(); |
| 40 |
|
private static final long valueOffset; |
| 41 |
|
|
| 42 |
|
/** |
| 52 |
|
* for longs. Called only once and cached in VM_SUPPORTS_LONG_CAS. |
| 53 |
|
*/ |
| 54 |
|
private static boolean VMSupportsCS8() { |
| 55 |
< |
try { |
| 56 |
< |
Class<?> klazz = java.util.concurrent.atomic.AtomicLong.class; |
| 57 |
< |
java.lang.reflect.Method m = |
| 58 |
< |
klazz.getDeclaredMethod("VMSupportsCS8", new Class<?>[0]); |
| 59 |
< |
m.setAccessible(true); |
| 60 |
< |
return (Boolean) m.invoke(new Class<?>[0]); |
| 61 |
< |
} catch (Throwable t) { throw new Error(t); } |
| 55 |
> |
final Class<?> klazz = java.util.concurrent.atomic.AtomicLong.class; |
| 56 |
> |
return java.security.AccessController.doPrivileged |
| 57 |
> |
(new java.security.PrivilegedAction<Boolean>() { |
| 58 |
> |
public Boolean run() { |
| 59 |
> |
try { |
| 60 |
> |
java.lang.reflect.Method m = |
| 61 |
> |
klazz.getDeclaredMethod("VMSupportsCS8", new Class<?>[0]); |
| 62 |
> |
m.setAccessible(true); |
| 63 |
> |
return (Boolean) m.invoke(new Class<?>[0]); |
| 64 |
> |
} catch (Throwable t) { throw new Error(t); } |
| 65 |
> |
}}); |
| 66 |
|
} |
| 67 |
|
|
| 68 |
|
static { |
| 110 |
|
* Eventually sets to the given value. |
| 111 |
|
* |
| 112 |
|
* @param newValue the new value |
| 111 |
– |
* @since 1.6 |
| 113 |
|
*/ |
| 114 |
|
public final void lazySet(double newValue) { |
| 115 |
|
unsafe.putOrderedLong(this, valueOffset, doubleToRawLongBits(newValue)); |
| 233 |
|
return get(); |
| 234 |
|
} |
| 235 |
|
|
| 236 |
+ |
/** |
| 237 |
+ |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
| 238 |
+ |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
| 239 |
+ |
* into a jdk. |
| 240 |
+ |
* |
| 241 |
+ |
* @return a sun.misc.Unsafe |
| 242 |
+ |
*/ |
| 243 |
+ |
private static sun.misc.Unsafe getUnsafe() { |
| 244 |
+ |
try { |
| 245 |
+ |
return sun.misc.Unsafe.getUnsafe(); |
| 246 |
+ |
} catch (SecurityException se) { |
| 247 |
+ |
try { |
| 248 |
+ |
return java.security.AccessController.doPrivileged |
| 249 |
+ |
(new java.security |
| 250 |
+ |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
| 251 |
+ |
public sun.misc.Unsafe run() throws Exception { |
| 252 |
+ |
java.lang.reflect.Field f = sun.misc |
| 253 |
+ |
.Unsafe.class.getDeclaredField("theUnsafe"); |
| 254 |
+ |
f.setAccessible(true); |
| 255 |
+ |
return (sun.misc.Unsafe) f.get(null); |
| 256 |
+ |
}}); |
| 257 |
+ |
} catch (java.security.PrivilegedActionException e) { |
| 258 |
+ |
throw new RuntimeException("Could not initialize intrinsics", |
| 259 |
+ |
e.getCause()); |
| 260 |
+ |
} |
| 261 |
+ |
} |
| 262 |
+ |
} |
| 263 |
+ |
|
| 264 |
|
} |
