Hi Duy, On Mon, Apr 30, 2018 at 7:45 AM, Duy Nguyen <pclo...@gmail.com> wrote: > On Mon, Apr 30, 2018 at 4:42 PM, Duy Nguyen <pclo...@gmail.com> wrote: >> On Sun, Apr 29, 2018 at 10:53 PM, Johannes Schindelin >> <johannes.schinde...@gmx.de> wrote: >>>> > @@ -1412,12 +1422,13 @@ int unpack_trees(unsigned len, struct tree_desc >>>> > *t, struct unpack_trees_options >>>> > WRITE_TREE_SILENT | >>>> > WRITE_TREE_REPAIR); >>>> > } >>>> > - move_index_extensions(&o->result, o->dst_index); >>>> > + move_index_extensions(&o->result, o->src_index); >>>> >>>> While this looks like the right thing to do on paper, I believe it's >>>> actually broken for a specific case of untracked cache. In short, >>>> please do not touch this line. I will send a patch to revert >>>> edf3b90553 (unpack-trees: preserve index extensions - 2017-05-08), >>>> which essentially deletes this line, with proper explanation and >>>> perhaps a test if I could come up with one. >>>> >>>> When we update the index, we depend on the fact that all updates must >>>> invalidate the right untracked cache correctly. In this unpack >>>> operations, we start copying entries over from src to result. Since >>>> 'result' (at least from the beginning) does not have an untracked >>>> cache, it has nothing to invalidate when we copy entries over. By the >>>> time we have done preparing 'result', what's recorded in src's (or >>>> dst's for that matter) untracked cache may or may not apply to >>>> 'result' index anymore. This copying only leads to more problems when >>>> untracked cache is used. >>> >>> Is there really no way to invalidate just individual entries? >> >> Grr.... the short answer is the current code (i.e. without Elijah's >> changes) works but in a twisted way. So you get to keep untracked >> cache in the end. > > GAAAHH.. it works _with_ Elijah's changes (since he made the change > from dst to src) not without (and no performance regression).
So...is that an Acked-by for the patch, or does the "two wrong make a right, I guess" comment suggest that we should still drop the move_index_extensions change (essentially reverting to v1 of the PATCH as found at 20180421193736.12722-1-new...@gmail.com), and you'll fix things up further in a separate series? > This file really messes my brain up. I'm glad I'm not the only one. :-) Elijah
