On Jun 14 2012, at 09:29 , Ulf Zibis wrote:
> Hi Mike,
>
> I like the 1-liner ... :-)
> int h = hashSeed ^ k.hashCode();
>
> ... but I'm still missing a little comment, what this xor with a hashSeed
> serves for. Such as brief, as the next following 3 lines about preventing
> from collisions.
The hashSeed randomizes table order to reduce the value of partial
collisions--only full collisions will predictably collide. The comment I think
you are looking for is on hashSeed itself.
/**
* A randomizing value associated with this instance that is applied to
* hash code of keys to make hash collisions harder to find.
*/
>
> WeakHashMap.hash(Object) could be private too, instead final.
OK. I will probably make it private method though I hate opening an issue just
for one keyword.
>
> And last... you have reinserted/left the space after the cast in some
> occurences. ;-)
Netbeans did actually. I don't do my own source formatting.
Mike
>
> -Ulf
>
> Am 14.06.2012 17:27, schrieb mike.dui...@oracle.com:
>> Changeset: 505455116320
>> Author: mduigou
>> Date: 2012-06-13 16:48 -0700
>> URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/505455116320
>>
>> 7173919: Minor optimization of hashing methods
>> Summary: several minor optimizations to hashing methods used by hash map
>> classes
>> Reviewed-by: dholmes
>>
>> ! src/share/classes/java/util/HashMap.java
>> ! src/share/classes/java/util/Hashtable.java
>> ! src/share/classes/java/util/WeakHashMap.java
>> ! src/share/classes/java/util/concurrent/ConcurrentHashMap.java
>>
>>
>
>
