From: Derrick Stolee Date: Tue, 1 May 2018 12:47:17 +0000 (+0000) Subject: commit: use generation numbers for in_merge_bases() X-Git-Tag: v2.19.0-rc0~192^2~5 X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/f9b8908b85247ef60001a683c281af0080e9ee77 commit: use generation numbers for in_merge_bases() The containment algorithm for 'git branch --contains' is different from that for 'git tag --contains' in that it uses is_descendant_of() instead of contains_tag_algo(). The expensive portion of the branch algorithm is computing merge bases. When a commit-graph file exists with generation numbers computed, we can avoid this merge-base calculation when the target commit has a larger generation number than the initial commits. Performance tests were run on a copy of the Linux repository where HEAD is contained in v4.13 but no earlier tag. Also, all tags were copied to branches and 'git branch --contains' was tested: Before: 60.0s After: 0.4s Rel %: -99.3% Reported-by: Jeff King Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano --- diff --git a/commit.c b/commit.c index 39a3749abd..3ecdc13356 100644 --- a/commit.c +++ b/commit.c @@ -1056,12 +1056,19 @@ int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit * { struct commit_list *bases; int ret = 0, i; + uint32_t min_generation = GENERATION_NUMBER_INFINITY; if (parse_commit(commit)) return ret; - for (i = 0; i < nr_reference; i++) + for (i = 0; i < nr_reference; i++) { if (parse_commit(reference[i])) return ret; + if (reference[i]->generation < min_generation) + min_generation = reference[i]->generation; + } + + if (commit->generation > min_generation) + return ret; bases = paint_down_to_common(commit, nr_reference, reference); if (commit->object.flags & PARENT2)