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authorBenno Evers <benno@bmevers.de>2020-02-26 17:48:53 (GMT)
committerJunio C Hamano <gitster@pobox.com>2020-02-26 20:14:12 (GMT)
commit30b1c7ad9d64695a65c23f922e6ffd2fd35660da (patch)
tree513f58dfd862fd8198ccf6fdccfffde83db897b2 /builtin
parent2d2118b814c11f509e1aa76cb07110f7231668dc (diff)
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describe: don't abort too early when searching tags
When searching the commit graph for tag candidates, `git-describe` will stop as soon as there is only one active branch left and it already found an annotated tag as a candidate. This works well as long as all branches eventually connect back to a common root, but if the tags are found across branches with no common ancestor B o----. \ o-----o---o----x A it can happen that the search on one branch terminates prematurely because a tag was found on another, independent branch. This scenario isn't quite as obscure as it sounds, since cloning with a limited depth often introduces many independent "dead ends" into the commit graph. The help text of `git-describe` states pretty clearly that when describing a commit D, the number appended to the emitted tag X should correspond to the number of commits found by `git log X..D`. Thus, this commit modifies the stopping condition to only abort the search when only one branch is left to search *and* all current best candidates are descendants from that branch. For repositories with a single root, this condition is always true: When the search is reduced to a single active branch, the current commit must be an ancestor of *all* tag candidates. This means that in the common case, this change will have no negative performance impact since the same number of commits as before will be traversed. Signed-off-by: Benno Evers <benno@bmevers.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin')
-rw-r--r--builtin/describe.c22
1 files changed, 18 insertions, 4 deletions
diff --git a/builtin/describe.c b/builtin/describe.c
index b6df81d..420f4c6 100644
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -376,11 +376,25 @@ static void describe_commit(struct object_id *oid, struct strbuf *dst)
if (!(c->object.flags & t->flag_within))
t->depth++;
}
+ /* Stop if last remaining path already covered by best candidate(s) */
if (annotated_cnt && !list) {
- if (debug)
- fprintf(stderr, _("finished search at %s\n"),
- oid_to_hex(&c->object.oid));
- break;
+ int best_depth = INT_MAX;
+ unsigned best_within = 0;
+ for (cur_match = 0; cur_match < match_cnt; cur_match++) {
+ struct possible_tag *t = &all_matches[cur_match];
+ if (t->depth < best_depth) {
+ best_depth = t->depth;
+ best_within = t->flag_within;
+ } else if (t->depth == best_depth) {
+ best_within |= t->flag_within;
+ }
+ }
+ if ((c->object.flags & best_within) == best_within) {
+ if (debug)
+ fprintf(stderr, _("finished search at %s\n"),
+ oid_to_hex(&c->object.oid));
+ break;
+ }
}
while (parents) {
struct commit *p = parents->item;