On Thu, Aug 9, 2018 at 12:39 AM Martin Ågren <martin.agren@xxxxxxxxx> wrote:
>
> On 9 August 2018 at 00:17, Stefan Beller <sbeller@xxxxxxxxxx> wrote:
> > +int oid_array_remove_if(struct oid_array *array,
> > + for_each_oid_fn fn,
> > + void *data)
> > +{
> > + int i, j;
> > + char *to_remove = xcalloc(array->nr, sizeof(char));
>
> Do you really need this scratch space?
I don't think so, when we reorder the items while iterating over them.
I though reordering them later would be easier, but I am not sure anymore.
>
> > + /* No oid_array_sort() here! See the api-oid-array.txt docs! */
> > +
> > + for (i = 0; i < array->nr; i++) {
> > + int ret = fn(array->oid + i, data);
> > + if (ret)
> > + to_remove[i] = 1;
> > + }
> > +
> > + i = 0, j = 0;
> > + while (i < array->nr && j < array->nr) {
> > + while (i < array->nr && !to_remove[i])
> > + i++;
> > + /* i at first marked for deletion or out */
> > + if (j < i)
> > + j = i;
> > + while (j < array->nr && to_remove[j])
> > + j++;
> > + /* j > i; j at first valid after first deletion range or out */
> > + if (i < array->nr && j < array->nr)
> > + oidcpy(&array->oid[i], &array->oid[j]);
> > + else if (i >= array->nr)
> > + assert(j >= array->nr);
> > + /* no pruning happened, keep original array->nr */
> > + else if (j >= array->nr)
> > + array->nr = i;
> > + }
> > +
> > + free(to_remove);
> > +
> > + return 0;
> > +}
>
> I can't entirely follow this index-fiddling, but then I haven't had my
> morning coffee yet, so please forgive me if this is nonsense. Would it
> suffice to let i point out where to place items (starting at the first
> item not to keep) and j where to take them from (i.e., the items to
> keep, after the initial run)?
I thought this is what happens, just after the actual loop of calls.
> > +int oid_array_remove_if(struct oid_array *array,
> > + for_each_oid_fn fn,
> > + void *data);
>
> Maybe some documentation here, but this seems to be following suit. ;-)
Worth mentioning: the order is kept stable. (c.f. shrink_potential_moved_blocks
in diff.c which also "compacts an array", but without stable order).
Thanks for the review. I'll try to rewrite this to be more legible.
Thanks,
Stefan
