14 |
|
* See the {@link java.util.concurrent.atomic} package specification |
15 |
|
* for description of the properties of atomic variables. |
16 |
|
* |
17 |
< |
* <p><a name="bitEquals">This class compares primitive {@code double} |
17 |
> |
* <p id="bitEquals">This class compares primitive {@code double} |
18 |
|
* values in methods such as {@link #compareAndSet} by comparing their |
19 |
|
* bitwise representation using {@link Double#doubleToRawLongBits}, |
20 |
|
* which differs from both the primitive double {@code ==} operator |
21 |
|
* and from {@link Double#equals}, as if implemented by: |
22 |
|
* <pre> {@code |
23 |
< |
* boolean bitEquals(double x, double y) { |
23 |
> |
* static boolean bitEquals(double x, double y) { |
24 |
|
* long xBits = Double.doubleToRawLongBits(x); |
25 |
|
* long yBits = Double.doubleToRawLongBits(y); |
26 |
|
* return xBits == yBits; |
32 |
|
public class AtomicDoubleArray implements java.io.Serializable { |
33 |
|
private static final long serialVersionUID = -2308431214976778248L; |
34 |
|
|
35 |
< |
private final long[] array; |
35 |
> |
private final transient long[] array; |
36 |
|
|
37 |
|
private long checkedByteOffset(int i) { |
38 |
|
if (i < 0 || i >= array.length) |
162 |
|
* if the current value is <a href="#bitEquals">bitwise equal</a> |
163 |
|
* to the expected value. |
164 |
|
* |
165 |
< |
* <p>May <a href="package-summary.html#Spurious">fail spuriously</a> |
166 |
< |
* and does not provide ordering guarantees, so is only rarely an |
167 |
< |
* appropriate alternative to {@code compareAndSet}. |
165 |
> |
* <p><a |
166 |
> |
* href="http://download.oracle.com/javase/7/docs/api/java/util/concurrent/atomic/package-summary.html#Spurious"> |
167 |
> |
* May fail spuriously and does not provide ordering guarantees</a>, |
168 |
> |
* so is only rarely an appropriate alternative to {@code compareAndSet}. |
169 |
|
* |
170 |
|
* @param i the index |
171 |
|
* @param expect the expected value |
223 |
|
if (iMax == -1) |
224 |
|
return "[]"; |
225 |
|
|
226 |
< |
StringBuilder b = new StringBuilder(); |
226 |
> |
// Double.toString(Math.PI).length() == 17 |
227 |
> |
StringBuilder b = new StringBuilder((17 + 2) * (iMax + 1)); |
228 |
|
b.append('['); |
229 |
< |
for (int i = 0; ; i++) { |
229 |
> |
for (int i = 0;; i++) { |
230 |
|
b.append(longBitsToDouble(getRaw(byteOffset(i)))); |
231 |
|
if (i == iMax) |
232 |
|
return b.append(']').toString(); |
234 |
|
} |
235 |
|
} |
236 |
|
|
237 |
+ |
/** |
238 |
+ |
* Saves the state to a stream (that is, serializes it). |
239 |
+ |
* |
240 |
+ |
* @param s the stream |
241 |
+ |
* @throws java.io.IOException if an I/O error occurs |
242 |
+ |
* @serialData The length of the array is emitted (int), followed by all |
243 |
+ |
* of its elements (each a {@code double}) in the proper order. |
244 |
+ |
*/ |
245 |
+ |
private void writeObject(java.io.ObjectOutputStream s) |
246 |
+ |
throws java.io.IOException { |
247 |
+ |
s.defaultWriteObject(); |
248 |
+ |
|
249 |
+ |
// Write out array length |
250 |
+ |
int length = length(); |
251 |
+ |
s.writeInt(length); |
252 |
+ |
|
253 |
+ |
// Write out all elements in the proper order. |
254 |
+ |
for (int i = 0; i < length; i++) |
255 |
+ |
s.writeDouble(get(i)); |
256 |
+ |
} |
257 |
+ |
|
258 |
+ |
/** |
259 |
+ |
* Reconstitutes the instance from a stream (that is, deserializes it). |
260 |
+ |
* @param s the stream |
261 |
+ |
* @throws ClassNotFoundException if the class of a serialized object |
262 |
+ |
* could not be found |
263 |
+ |
* @throws java.io.IOException if an I/O error occurs |
264 |
+ |
*/ |
265 |
+ |
private void readObject(java.io.ObjectInputStream s) |
266 |
+ |
throws java.io.IOException, ClassNotFoundException { |
267 |
+ |
s.defaultReadObject(); |
268 |
+ |
|
269 |
+ |
// Read in array length and allocate array |
270 |
+ |
int length = s.readInt(); |
271 |
+ |
unsafe.putObjectVolatile(this, arrayOffset, new long[length]); |
272 |
+ |
|
273 |
+ |
// Read in all elements in the proper order. |
274 |
+ |
for (int i = 0; i < length; i++) |
275 |
+ |
set(i, s.readDouble()); |
276 |
+ |
} |
277 |
+ |
|
278 |
|
// Unsafe mechanics |
279 |
|
private static final sun.misc.Unsafe unsafe = getUnsafe(); |
280 |
+ |
private static final long arrayOffset; |
281 |
|
private static final int base = unsafe.arrayBaseOffset(long[].class); |
282 |
|
private static final int shift; |
283 |
|
|
284 |
|
static { |
285 |
< |
int scale = unsafe.arrayIndexScale(long[].class); |
286 |
< |
if ((scale & (scale - 1)) != 0) |
287 |
< |
throw new Error("data type scale not a power of two"); |
288 |
< |
shift = 31 - Integer.numberOfLeadingZeros(scale); |
285 |
> |
try { |
286 |
> |
Class<?> k = AtomicDoubleArray.class; |
287 |
> |
arrayOffset = unsafe.objectFieldOffset |
288 |
> |
(k.getDeclaredField("array")); |
289 |
> |
int scale = unsafe.arrayIndexScale(long[].class); |
290 |
> |
if ((scale & (scale - 1)) != 0) |
291 |
> |
throw new Error("data type scale not a power of two"); |
292 |
> |
shift = 31 - Integer.numberOfLeadingZeros(scale); |
293 |
> |
} catch (Exception e) { |
294 |
> |
throw new Error(e); |
295 |
> |
} |
296 |
|
} |
297 |
|
|
298 |
|
/** |
305 |
|
private static sun.misc.Unsafe getUnsafe() { |
306 |
|
try { |
307 |
|
return sun.misc.Unsafe.getUnsafe(); |
308 |
< |
} catch (SecurityException se) { |
309 |
< |
try { |
310 |
< |
return java.security.AccessController.doPrivileged |
311 |
< |
(new java.security |
312 |
< |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
313 |
< |
public sun.misc.Unsafe run() throws Exception { |
314 |
< |
java.lang.reflect.Field f = sun.misc |
315 |
< |
.Unsafe.class.getDeclaredField("theUnsafe"); |
316 |
< |
f.setAccessible(true); |
317 |
< |
return (sun.misc.Unsafe) f.get(null); |
318 |
< |
}}); |
319 |
< |
} catch (java.security.PrivilegedActionException e) { |
320 |
< |
throw new RuntimeException("Could not initialize intrinsics", |
321 |
< |
e.getCause()); |
322 |
< |
} |
308 |
> |
} catch (SecurityException tryReflectionInstead) {} |
309 |
> |
try { |
310 |
> |
return java.security.AccessController.doPrivileged |
311 |
> |
(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
312 |
> |
public sun.misc.Unsafe run() throws Exception { |
313 |
> |
Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class; |
314 |
> |
for (java.lang.reflect.Field f : k.getDeclaredFields()) { |
315 |
> |
f.setAccessible(true); |
316 |
> |
Object x = f.get(null); |
317 |
> |
if (k.isInstance(x)) |
318 |
> |
return k.cast(x); |
319 |
> |
} |
320 |
> |
throw new NoSuchFieldError("the Unsafe"); |
321 |
> |
}}); |
322 |
> |
} catch (java.security.PrivilegedActionException e) { |
323 |
> |
throw new RuntimeException("Could not initialize intrinsics", |
324 |
> |
e.getCause()); |
325 |
|
} |
326 |
|
} |
327 |
|
} |