Re: [PATCH v2 4/4] log: --author-date-order

Jeff King [off-list ref] writes:

quoted

Or we could extend parse_commit() API to take an optional commit
info slab to store not just author date but other non-essential
stuff like people's names, and we arrange that extended API to be
triggered when we know --author-date-order is in effect?

I like the latter option. It takes a non-trivial amount of time to load
the commits from disk, and now we are potentially doing it 2 or 3 times
for a run (once to parse, once to get the author info for topo-sort, and
possibly later to show it if --pretty is given; though I did not check
and maybe we turn off save_commit_buffer with --pretty). It would be
nice to have an extended parse_object that handled that. I'm not sure of
the interface. Maybe variadic with pairs of type/slab, like:

  parse_commit_extended(commit,
                        PARSE_COMMIT_AUTHORDATE, &authordate_slab,
                        PARSE_COMMIT_DONE);

?

What I had in mind actually was a custom slab tailored for each
caller that is an array of struct.  If the caller is interested in
authordate and authorname, instead of populating two separate
authordate_slab and authorname_slab, the caller declares a

	struct {
        	unsigned long date;
                char name[FLEX_ARRAY];
	} author_info;

prepares author_info_slab, and use your commit_parser API to fill
them.