| 150 |
|
* defends against poor quality hash functions. This is critical |
| 151 |
|
* because ConcurrentHashMap uses power-of-two length hash tables, |
| 152 |
|
* that otherwise encounter collisions for hashCodes that do not |
| 153 |
< |
* differ in lower bits. |
| 153 |
> |
* differ in lower or upper bits. |
| 154 |
|
*/ |
| 155 |
|
private static int hash(int h) { |
| 156 |
|
// Spread bits to regularize both segment and index locations, |
| 157 |
< |
// using variant of Jenkins's shift-based hash. |
| 158 |
< |
h += ~(h << 13); |
| 159 |
< |
h ^= h >>> 7; |
| 160 |
< |
h += h << 3; |
| 161 |
< |
h ^= h >>> 17; |
| 162 |
< |
h += h << 5; |
| 163 |
< |
return h; |
| 157 |
> |
// using variant of single-word Wang/Jenkins hash. |
| 158 |
> |
h += (h << 15) ^ 0xffffcd7d; |
| 159 |
> |
h ^= (h >>> 10); |
| 160 |
> |
h += (h << 3); |
| 161 |
> |
h ^= (h >>> 6); |
| 162 |
> |
h += (h << 2) + (h << 14); |
| 163 |
> |
return h ^ (h >>> 16); |
| 164 |
|
} |
| 165 |
|
|
| 166 |
|
/** |
