Hi Junio,
On Fri, 29 Jul 2016, Junio C Hamano wrote:
> Kevin Willford <kcwillford@xxxxxxxxx> writes:
>
> > static int patch_id_cmp(struct patch_id *a,
> > struct patch_id *b,
> > - void *keydata)
> > + struct diff_options *opt)
> > {
> > + if (is_null_sha1(a->patch_id) &&
> > + commit_patch_id(a->commit, opt, a->patch_id, 0))
> > + return error("Could not get patch ID for %s",
> > + oid_to_hex(&a->commit->object.oid));
> > + if (is_null_sha1(b->patch_id) &&
> > + commit_patch_id(b->commit, opt, b->patch_id, 0))
> > + return error("Could not get patch ID for %s",
> > + oid_to_hex(&b->commit->object.oid));
> > return hashcmp(a->patch_id, b->patch_id);
> > }
>
> These error returns initially looks slightly iffy in that in general
> the caller of any_cmp_fn() wants to know how a/b compares, but by
> returning error(), it always says "a is smaller than b".
I am to blame, as this is my design.
And yes, it is kind of funny that we require a cmpfn that returns <0, ==0
and >0 for comparisons, when hashmaps try to avoid any order.
Do you want a note in the commit message about this "abuse" of a negative
return value, or a code comment?
> The idea of using the two level hash, computing the more expensive
> one only when the hashmap hashes of the result of the cheaper hash
> function collide, is excellent.
Thanks :-)
Ciao,
Dscho
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