RFR 8055283: Expand ResourceHashtable with C_HEAP allocation, removal and some unit tests

[Coleen Phillimore]

The default hash table in hashtable.hpp is a C Heap allocated hash table.

Coleen

On 8/18/14, 10:24 AM, Mikael Gerdin wrote:
> Hi all!
>
> For an upcoming change I need to allocate ResourceHashtables as c-heap 
> objects instead of arena objects. Since the ResourceObj allocation 
> type typically supports c-heap allocation I extended ResourceHashtable 
> with the functionality.
> I also need a remove method and a size estimate, added those as well.
>
> Additionally, I took the liberty to fix the default hash function 
> which appears to be a typo:
> return hash ^ (hash > 3);
>  // just in case we're dealing with aligned ptrs
>
> I don't think the intention was to xor with "true" if hash was greater 
> than 3, especially given the comment about aligned ptrs.
>
> I assume that the original author meant to shift hash to the right 
> since aligned pointers will have a bunch of zeros in the low bits.
>
> I also took the liberty to add some simple unit tests to the class to 
> avoid breaking something.
>
> Testing: JPRT (including the new unit test) and vm.defmeth.testlist 
> (since default methods seems to be the only user of the default hash 
> function)
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8055283
>
> Webrev: http://cr.openjdk.java.net/~mgerdin/8055283/webrev.0
>
> /Mikael