[sldev] LLUUIDHashMap vs hash_map

[Dale Glass]

On Thu, Sep 20, 2007 at 01:20:48PM +0200, Dale Glass wrote:
> I'm looking at implementing a cache storing data by LLUUID and found the
> LLUUIDHashMap. I see it seems to be used only in LLMotionRegistry.
> 
> Should I use it? How about making a hash function for LLUUID and using
> that instead? I presume that simply using the first/last
> sizeof(size_t)*8 bits of the LLUUID would work fine.

Been looking a bit more at the source of LLUUIDHashMap, it's weird.

It's hardcoded to 256 buckets, not even as a constant but as a magic
number in the source (ick!)

It uses an U8 for the hash key, so it can't go higher anyway.

LLUUIDHashNode stores a number of elements that varies depending on the
argument to the template (why?)


So I'm thinking a hash_map could be better for my purposes, as I might
want more than 256 elements (cache will probably be quite big).

For the hash function I'm considering this:

size_t operator()(const LLUUID&x)
{
	return (size_t)x.getCRC32();
}


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