From 8d00d7c3df8b7947c9154873116b5153c1a84dbf Mon Sep 17 00:00:00 2001 From: Abhishek Kumar Date: Sat, 16 Jan 2021 18:11:17 +0000 Subject: commit-reach: use corrected commit dates in paint_down_to_common() 091f4cf (commit: don't use generation numbers if not needed, 2018-08-30) changed paint_down_to_common() to use commit dates instead of generation numbers v1 (topological levels) as the performance regressed on certain topologies. With generation number v2 (corrected commit dates) implemented, we no longer have to rely on commit dates and can use generation numbers. For example, the command `git merge-base v4.8 v4.9` on the Linux repository walks 167468 commits, taking 0.135s for committer date and 167496 commits, taking 0.157s for corrected committer date respectively. While using corrected commit dates, Git walks nearly the same number of commits as commit date, the process is slower as for each comparision we have to access a commit-slab (for corrected committer date) instead of accessing struct member (for committer date). This change incidentally broke the fragile t6404-recursive-merge test. t6404-recursive-merge sets up a unique repository where all commits have the same committer date without a well-defined merge-base. While running tests with GIT_TEST_COMMIT_GRAPH unset, we use committer date as a heuristic in paint_down_to_common(). 6404.1 'combined merge conflicts' merges commits in the order: - Merge C with B to form an intermediate commit. - Merge the intermediate commit with A. With GIT_TEST_COMMIT_GRAPH=1, we write a commit-graph and subsequently use the corrected committer date, which changes the order in which commits are merged: - Merge A with B to form an intermediate commit. - Merge the intermediate commit with C. While resulting repositories are equivalent, 6404.4 'virtual trees were processed' fails with GIT_TEST_COMMIT_GRAPH=1 as we are selecting different merge-bases and thus have different object ids for the intermediate commits. As this has already causes problems (as noted in 859fdc0 (commit-graph: define GIT_TEST_COMMIT_GRAPH, 2018-08-29)), we disable commit graph within t6404-recursive-merge. Signed-off-by: Abhishek Kumar Reviewed-by: Taylor Blau Reviewed-by: Derrick Stolee Signed-off-by: Junio C Hamano --- t/t6404-recursive-merge.sh | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 't/t6404-recursive-merge.sh') diff --git a/t/t6404-recursive-merge.sh b/t/t6404-recursive-merge.sh index b1c3d4dda4..86f74ae584 100755 --- a/t/t6404-recursive-merge.sh +++ b/t/t6404-recursive-merge.sh @@ -15,6 +15,8 @@ GIT_COMMITTER_DATE="2006-12-12 23:28:00 +0100" export GIT_COMMITTER_DATE test_expect_success 'setup tests' ' + GIT_TEST_COMMIT_GRAPH=0 && + export GIT_TEST_COMMIT_GRAPH && echo 1 >a1 && git add a1 && GIT_AUTHOR_DATE="2006-12-12 23:00:00" git commit -m 1 a1 && @@ -66,7 +68,7 @@ test_expect_success 'setup tests' ' ' test_expect_success 'combined merge conflicts' ' - test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git merge -m final G + test_must_fail git merge -m final G ' test_expect_success 'result contains a conflict' ' @@ -82,6 +84,7 @@ test_expect_success 'result contains a conflict' ' ' test_expect_success 'virtual trees were processed' ' + # TODO: fragile test, relies on ambigious merge-base resolution git ls-files --stage >out && cat >expect <<-EOF && -- cgit v1.2.3