Re: [PATCH 2/2] for-each-ref: add --count-matches option

Phillip Wood <phillip.wood123@gmail.com> writes:

This is interesting. The default format over just 'x' is to concatenate the refname with hexadecimal form of the object name, while (at least as the code originally was intended):

 * the cost of parsing the "--format=<format>" string into series of
   atoms is one-time O(1), and there is nothing specially tricky in
   there.

 * the cost of computing these atoms should be miniscule, as
   in the default format, the per-ref cost come from these:

   - populate_value() -> get_refname() -> show_ref() for the refname
     would merely be a xstrdup() of the refname.

   - populate_value() -> grab_oid() -> do_grab_oid() should be using
     O_FULL so there shouldn't be any find_unique_abbrev() cost.
     Just binary-to-hex.

   - populate_value() -> get_object() -> oid_object_info_extended() ->
     grab_common_values() asks for ATOM_OBJECTTYPE that should be a
     single xstrdup(), but oid_object_info_extended() needs to parse
     the object, but .info.contentp ought to be NULL and we should
     not be calling parse_object_buffer().

So it might be worth looking into where the time is going (didn't Peff or somebody do that a few years ago, though?) when using the default format and optimize or special case the codepath, but the responses I have seen from two of you makes me suspect that the new option is not the best general approach.

Thanks.