The ref_newer method is used by 'git push' to check if a force-push is
required. This method does not use any kind of cutoff when walking, so
in the case of a force-push will walk all reachable commits.
The is_descendant_of method already uses paint_down_to_common along with
cutoffs. By translating the ref_newer arguments into the commit and
commit_list required by is_descendant_of, we can have one fewer commit
walk and also improve our performance!
For a copy of the Linux repository, 'test-tool reach ref_newer' presents
the following improvements with the specified input. In the case that
ref_newer returns 1, there is no improvement. The improvement is in the
second case where ref_newer returns 0.
Input:
A:v4.9
B:v3.19
Before: 0.09 s
After: 0.09 s
To test the negative case, add a new commit with parent v3.19,
regenerate the commit-graph, and then run with B pointing at that
commit.
Before: 0.43 s
After: 0.09 s
Signed-off-by: Derrick Stolee <dsto...@microsoft.com>
---
commit-reach.c | 26 +++-----------------------
1 file changed, 3 insertions(+), 23 deletions(-)
diff --git a/commit-reach.c b/commit-reach.c
index 940fbf2e17..f5858944fd 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -366,20 +366,11 @@ void reduce_heads_replace(struct commit_list **heads)
*heads = result;
}
-static void unmark_and_free(struct commit_list *list, unsigned int mark)
-{
- while (list) {
- struct commit *commit = pop_commit(&list);
- commit->object.flags &= ~mark;
- }
-}
-
int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
{
struct object *o;
struct commit *old_commit, *new_commit;
- struct commit_list *list, *used;
- int found = 0;
+ struct commit_list *old_commit_list = NULL;
/*
* Both new_commit and old_commit must be commit-ish and new_commit is
descendant of
@@ -400,19 +391,8 @@ int ref_newer(const struct object_id *new_oid, const
struct object_id *old_oid)
if (parse_commit(new_commit) < 0)
return 0;
- used = list = NULL;
- commit_list_insert(new_commit, &list);
- while (list) {
- new_commit = pop_most_recent_commit(&list, TMP_MARK);
- commit_list_insert(new_commit, &used);
- if (new_commit == old_commit) {
- found = 1;
- break;
- }
- }
- unmark_and_free(list, TMP_MARK);
- unmark_and_free(used, TMP_MARK);
- return found;
+ commit_list_insert(old_commit, &old_commit_list);
+ return is_descendant_of(new_commit, old_commit_list);
}
/*
--
2.18.0.118.gd4f65b8d14
