From: Linus Torvalds Date: Fri, 10 Aug 2007 19:31:20 +0000 (-0700) Subject: Optimize the two-way merge of git-read-tree too X-Git-Tag: v1.5.3-rc5~36 X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=d699676dda5fdf0996601006c3bac2a9c077a862;p=git.git Optimize the two-way merge of git-read-tree too This trivially optimizes the two-way merge case of git-read-tree too, which affects switching branches. When you have tons and tons of files in your repository, but there are only small differences in the branches (maybe just a couple of files changed), the biggest cost of the branch switching was actually just the index calculations. This fixes it (timings for switching between the "testing" and "master" branches in the 100,000 file testing-repo-from-hell, where the branches only differ in one small file). Before: [torvalds@woody bummer]$ time git checkout master real 0m9.919s user 0m8.461s sys 0m0.264s After: [torvalds@woody bummer]$ time git checkout testing real 0m0.576s user 0m0.348s sys 0m0.228s so it's easily an order of magnitude different. This concludes the series. I think we could/should do the three-way merge too (to speed up merges), but I'm lazy. Somebody else can do it. The rule is very simple: you need to remove the old entry if: - you want to remove the file entirely - you replace it with a "merge conflict" entry (ie a non-stage-0 entry) and you can avoid removing it if you either - keep the old one - or resolve it to a new one. and these rules should all be valid for the three-way case too. Signed-off-by: Linus Torvalds Signed-off-by: Junio C Hamano --- diff --git a/unpack-trees.c b/unpack-trees.c index d57b91c1b..fda7729f1 100644 --- a/unpack-trees.c +++ b/unpack-trees.c @@ -827,7 +827,6 @@ int twoway_merge(struct cache_entry **src, struct cache_entry *oldtree = src[1]; struct cache_entry *newtree = src[2]; - remove_entry(remove); if (o->merge_size != 2) return error("Cannot do a twoway merge of %d trees", o->merge_size); @@ -850,6 +849,7 @@ int twoway_merge(struct cache_entry **src, } else if (oldtree && !newtree && same(current, oldtree)) { /* 10 or 11 */ + remove_entry(remove); return deleted_entry(oldtree, current, o); } else if (oldtree && newtree && @@ -859,6 +859,7 @@ int twoway_merge(struct cache_entry **src, } else { /* all other failures */ + remove_entry(remove); if (oldtree) reject_merge(oldtree); if (current) @@ -870,8 +871,8 @@ int twoway_merge(struct cache_entry **src, } else if (newtree) return merged_entry(newtree, current, o); - else - return deleted_entry(oldtree, current, o); + remove_entry(remove); + return deleted_entry(oldtree, current, o); } /*