New hash

[H. S. Teoh]

On Sat, Mar 24, 2012 at 07:49:13AM -0600, Andrei Alexandrescu wrote:
> On 3/23/12 10:47 PM, Andrej Mitrovic wrote:
> >On 3/24/12, Andrej Mitrovic<andrej.mitrovich at gmail.com>  wrote:
> >>snip
> >
> >I've managed to test the hashes on a small-sized closed-source
> >project (9K lines) which used hashes a lot. I've found no issues so
> >far (no memory corruption or anything). Performance did drop a bit
> >from 812msecs to 898msecs. I can't extensively test this yet because
> >I can't serialize the hashes (a serialization library doesn't want to
> >work with the new hashes but I'll fix that) and so I need a 30second
> >run that first fills the hashes before doing work on them. But it
> >does seem to be a tiny bit slower.
> 
> I wonder what the matter is. What hashing function does the new hash
> use? Let me reiterate the suggestion that different hash algorithms
> are used depending on the string length.
[...]

I used the same hashing functions as before. Of course, I did move
things around a bit, so some stuff may have gotten shuffled around
unwittingly. The only actual difference in hash function that I'm aware
of is with const(char)[], which in the present druntime is inconsistent
with char[] and string. But this can't be the source of the problem,
because, if anything, the hash function I substituted (which is the same
as that for char[] and string currently) should be *faster*.


T

-- 
There are four kinds of lies: lies, damn lies, and statistics.