Re: Change GUC hashtable to use simplehash?

On 22.01.24 03:03, John Naylor wrote:
> I wrote:
>> fasthash_init(&hs, sizeof(Datum), kind);
>> fasthash_accum(&hs, (char *) &value, sizeof(Datum));
>> return fasthash_final32(&hs, 0);
> It occurred to me that it's strange to have two places that length can
> be passed. That was a side effect of the original, which used length
> to both know how many bytes to read, and to modify the internal seed.
> With the incremental API, it doesn't make sense to pass the length (or
> a dummy macro) up front -- with a compile-time fixed length, it can't
> possibly break a tie, so it's just noise.
>
> 0001 removes the length from initialization in the incremental
> interface. The standalone functions use length directly the same as
> before, but after initialization. Thoughts?

Unrelated related issue: src/include/common/hashfn_unstable.h currently
causes warnings from cpluspluscheck:

/tmp/cirrus-ci-build/src/include/common/hashfn_unstable.h: In function
‘int fasthash_accum_cstring_unaligned(fasthash_state*, const char*)’:
/tmp/cirrus-ci-build/src/include/common/hashfn_unstable.h:201:20:
warning: comparison of integer expressions of different signedness:
‘int’ and ‘long unsigned int’ [-Wsign-compare]
201 | while (chunk_len < FH_SIZEOF_ACCUM && str[chunk_len] != '\0')
| ^

and a few more like that.

I think it would be better to declare various int variables and
arguments as size_t instead. Even if you don't actually need the larger
range, it would make it more self-documenting.