On Fri, Aug 10, 2018 at 9:40 PM Elijah Newren <new...@gmail.com> wrote: > > On Fri, Aug 10, 2018 at 12:30 PM Duy Nguyen <pclo...@gmail.com> wrote: > > On Fri, Aug 10, 2018 at 8:39 PM Elijah Newren <new...@gmail.com> wrote: > ... > > > Why do we still need to go through add_index_entry()? I thought that > > > the whole point was that you already checked that at the current path, > > > the trees being unpacked were all equal and matched both the index and > > > the cache_tree. If so, why is there any need for an update at all? > > > (Did I read your all_trees_same_as_cache_tree() function wrong, and > > > you don't actually know these all match in some important way?) > > > > Unless fn is oneway_diff, we have to create a new index (in o->result) > > based on o->src_index and some other trees. So we have to add entries > > Oh, right, o->src_index may not equal o->dst_index (because of people > like me who call it that way from merge-recursive.c) and even if it > does, we still have the temporary o->result in the mean time. I > should have remembered that; just didn't.
Your forgetting about this actually helps. I think the idea of avoiding add_index_entry() may be worth considering. We know that 90% of cases of unpack_trees() is from the_index to the_index. So if instead of creating a full temporary index, where 90% of it might be the same as source index, if we just mark in the source index (e.g. in ce_flags) the entries that should be copied to o->result and _not_ create them in o->result. When it's time to create o->dst_index (which is the_index) from o->result, we could just do little manipulation to delete stuff that the_index has but o->result does not and add a bit more things. It is something that at least sounds nice in my head, but I'm not sure if it works out... -- Duy
