| 111 |
|
} |
| 112 |
|
|
| 113 |
|
/** |
| 114 |
< |
* Holder for the thread-local hash code. The code is initially |
| 115 |
< |
* random, but may be set to a different value upon collisions. |
| 114 |
> |
* ThreadLocal holding a single-slot int array holding hash code. |
| 115 |
> |
* Unlike the JDK8 version of this class, we use a suboptimal |
| 116 |
> |
* int[] representation to avoid introducing a new type that can |
| 117 |
> |
* impede class-unloading when ThreadLocals are not removed. |
| 118 |
|
*/ |
| 119 |
< |
static final class HashCode { |
| 118 |
< |
static final Random rng = new Random(); |
| 119 |
< |
int code; |
| 120 |
< |
HashCode() { |
| 121 |
< |
int h = rng.nextInt(); // Avoid zero to allow xorShift rehash |
| 122 |
< |
code = (h == 0) ? 1 : h; |
| 123 |
< |
} |
| 124 |
< |
} |
| 119 |
> |
static final ThreadLocal<int[]> threadHashCode = new ThreadLocal<int[]>(); |
| 120 |
|
|
| 121 |
|
/** |
| 122 |
< |
* The corresponding ThreadLocal class |
| 122 |
> |
* Generator of new random hash codes |
| 123 |
|
*/ |
| 124 |
< |
static final class ThreadHashCode extends ThreadLocal<HashCode> { |
| 130 |
< |
public HashCode initialValue() { return new HashCode(); } |
| 131 |
< |
} |
| 132 |
< |
|
| 133 |
< |
/** |
| 134 |
< |
* Static per-thread hash codes. Shared across all instances to |
| 135 |
< |
* reduce ThreadLocal pollution and because adjustments due to |
| 136 |
< |
* collisions in one table are likely to be appropriate for |
| 137 |
< |
* others. |
| 138 |
< |
*/ |
| 139 |
< |
static final ThreadHashCode threadHashCode = new ThreadHashCode(); |
| 124 |
> |
static final Random rng = new Random(); |
| 125 |
|
|
| 126 |
|
/** Number of CPUS, to place bound on table size */ |
| 127 |
|
static final int NCPU = Runtime.getRuntime().availableProcessors(); |
| 184 |
|
* @param hc the hash code holder |
| 185 |
|
* @param wasUncontended false if CAS failed before call |
| 186 |
|
*/ |
| 187 |
< |
final void retryUpdate(long x, HashCode hc, boolean wasUncontended) { |
| 188 |
< |
int h = hc.code; |
| 187 |
> |
final void retryUpdate(long x, int[] hc, boolean wasUncontended) { |
| 188 |
> |
int h; |
| 189 |
> |
if (hc == null) { |
| 190 |
> |
threadHashCode.set(hc = new int[1]); // Initialize randomly |
| 191 |
> |
int r = rng.nextInt(); // Avoid zero to allow xorShift rehash |
| 192 |
> |
h = hc[0] = (r == 0) ? 1 : r; |
| 193 |
> |
} |
| 194 |
> |
else |
| 195 |
> |
h = hc[0]; |
| 196 |
|
boolean collide = false; // True if last slot nonempty |
| 197 |
|
for (;;) { |
| 198 |
|
Cell[] as; Cell a; int n; long v; |
| 245 |
|
h ^= h << 13; // Rehash |
| 246 |
|
h ^= h >>> 17; |
| 247 |
|
h ^= h << 5; |
| 248 |
+ |
hc[0] = h; // Record index for next time |
| 249 |
|
} |
| 250 |
|
else if (busy == 0 && cells == as && casBusy()) { |
| 251 |
|
boolean init = false; |
| 265 |
|
else if (casBase(v = base, fn(v, x))) |
| 266 |
|
break; // Fall back on using base |
| 267 |
|
} |
| 275 |
– |
hc.code = h; // Record index for next time |
| 268 |
|
} |
| 269 |
|
|
| 270 |
|
|
