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

[Mikael Gerdin]

Hi all,

Here's an old favorite. I'm yet again in need of a simple-to-use hash 
table in a place where resource allocation is impossible to use.

The idea is to add a ResourceObj::allocation_type template parameter to 
ResourceHashtable to allow a user to specify C-heap allocation using 
ResourceObj::C_Heap.

Currently if one tries to do
{
ResourceMark rm;
ResourceHash* hash = new (ResourceObj::C_HEAP) ResourceHash();
hash->put(...)
}
hash->get(...)

The get()-call will crash because the allocation of the hash table nodes 
does not respect the C_HEAP parameter.

To sweeten the deal a little I add support for removing elements and 
also a small bunch of unit tests to verify that the operations work as 
expected.

I also discovered a small issue with the primitive_hash() function which 
is the default one:
   36 template<typename K> unsigned primitive_hash(const K& k) {
   37   unsigned hash = (unsigned)((uintptr_t)k);
   38   return hash ^ (hash > 3); // just in case we're dealing with 
aligned ptrs
   39 }

It xors hash with the boolean expression (hash > 3) instead of what was 
probably intended (hash >> 3) to deal with aligned pointers as the 
comment suggests.
It appears that the only user of ResourceHash which doesn't specify its 
own hash function is MethodFamily::_member_index so it would be nice if 
someone could point me at any default method tests to verify that a 
proper hash function doesn't break anything.

Bug: https://bugs.openjdk.java.net/browse/JDK-8055283
Webrev: http://cr.openjdk.java.net/~mgerdin/8055283/webrev.1/

Testing: JPRT
RBT (Kitchensnk, hotspot/test/:hotspot_all)


Thanks!
/Mikael