On Mon, Apr 30, 2018 at 4:42 PM, Duy Nguyen <pclouds@xxxxxxxxx> wrote: > On Sun, Apr 29, 2018 at 10:53 PM, Johannes Schindelin > <Johannes.Schindelin@xxxxxx> 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). This file really messes my brain up. -- Duy
