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authorJunio C Hamano <gitster@pobox.com>2017-03-29 14:39:16 (GMT)
committerJunio C Hamano <gitster@pobox.com>2017-03-29 17:53:35 (GMT)
commitef1e74065c19cc427c4a1b322154fd55d7a3588b (patch)
tree0adbc26d0d65de5cc84b2a2ccbc5a9a703a3f8c7 /builtin
parent0041bf6544b9b46022b6362eae834a36505d7baa (diff)
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name-rev: favor describing with tags and use committer date to tiebreak
"git name-rev" assigned a phony "far in the future" date to tips of refs that are not pointing at tag objects, and favored names based on a ref with the oldest date. This made it almost impossible for an unannotated tags and branches to be counted as a viable base, which was especially problematic when the command is run with the "--tags" option. If an unannotated tag that points at an ancient commit and an annotated tag that points at a much newer commit reaches the commit that is being named, the old unannotated tag was ignored. Update the "taggerdate" field of the rev-name structure, which is initialized from the tip of ref, to have the committer date if the object at the tip of ref is a commit, not a tag, so that we can optionally take it into account when doing "is this name better?" comparison logic. When "name-rev" is run without the "--tags" option, the general expectation is still to name the commit based on a tag if possible, but use non-tag refs as fallback, and tiebreak among these non-tag refs by favoring names with shorter hops from the tip. The use of a phony "far in the future" date in the original code was an effective way to ensure this expectation is held: a non-tag tip gets the same "far in the future" timestamp, giving precedence to tags, and among non-tag tips, names with shorter hops are preferred over longer hops, without taking the "taggerdate" into account. As we are taking over the "taggerdate" field to store the committer date for tips with commits: (1) keep the original logic when comparing names based on two refs both of which are from refs/tags/; (2) favoring a name based on a ref in refs/tags/ hierarchy over a ref outside the hierarchy; (3) between two names based on a ref both outside refs/tags/, give precedence to a name with shorter hops and use "taggerdate" only to tie-break. A change to t4202 is a natural consequence. The test creates a commit on a branch "side" and points at it with an unannotated tag "refs/tags/side-2". The original code couldn't decide which one to favor at all, and gave a name based on a branch (simply because refs/heads/side sorts earlier than refs/tags/side-2). Because the updated logic is taught to favor refs in refs/tags/ hierarchy, the the test is updated to expect to see tags/side-2 instead. [mjg: open-coded the comparisons in is_better_name(), dropping a helper macro used in the original] Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Michael J Gruber <git@grubix.eu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin')
-rw-r--r--builtin/name-rev.c53
1 files changed, 44 insertions, 9 deletions
diff --git a/builtin/name-rev.c b/builtin/name-rev.c
index 7890f82..bf7ed01 100644
--- a/builtin/name-rev.c
+++ b/builtin/name-rev.c
@@ -13,6 +13,7 @@ typedef struct rev_name {
unsigned long taggerdate;
int generation;
int distance;
+ int from_tag;
} rev_name;
static long cutoff = LONG_MAX;
@@ -24,16 +25,43 @@ static int is_better_name(struct rev_name *name,
const char *tip_name,
unsigned long taggerdate,
int generation,
- int distance)
+ int distance,
+ int from_tag)
{
- return (name->taggerdate > taggerdate ||
- (name->taggerdate == taggerdate &&
- name->distance > distance));
+ /*
+ * When comparing names based on tags, prefer names
+ * based on the older tag, even if it is farther away.
+ */
+ if (from_tag && name->from_tag)
+ return (name->taggerdate > taggerdate ||
+ (name->taggerdate == taggerdate &&
+ name->distance > distance));
+
+ /*
+ * We know that at least one of them is a non-tag at this point.
+ * favor a tag over a non-tag.
+ */
+ if (name->from_tag != from_tag)
+ return from_tag;
+
+ /*
+ * We are now looking at two non-tags. Tiebreak to favor
+ * shorter hops.
+ */
+ if (name->distance != distance)
+ return name->distance > distance;
+
+ /* ... or tiebreak to favor older date */
+ if (name->taggerdate != taggerdate)
+ return name->taggerdate > taggerdate;
+
+ /* keep the current one if we cannot decide */
+ return 0;
}
static void name_rev(struct commit *commit,
const char *tip_name, unsigned long taggerdate,
- int generation, int distance,
+ int generation, int distance, int from_tag,
int deref)
{
struct rev_name *name = (struct rev_name *)commit->util;
@@ -57,12 +85,13 @@ static void name_rev(struct commit *commit,
commit->util = name;
goto copy_data;
} else if (is_better_name(name, tip_name, taggerdate,
- generation, distance)) {
+ generation, distance, from_tag)) {
copy_data:
name->tip_name = tip_name;
name->taggerdate = taggerdate;
name->generation = generation;
name->distance = distance;
+ name->from_tag = from_tag;
} else
return;
@@ -82,10 +111,12 @@ copy_data:
parent_number);
name_rev(parents->item, new_name, taggerdate, 0,
- distance + MERGE_TRAVERSAL_WEIGHT, 0);
+ distance + MERGE_TRAVERSAL_WEIGHT,
+ from_tag, 0);
} else {
name_rev(parents->item, tip_name, taggerdate,
- generation + 1, distance + 1, 0);
+ generation + 1, distance + 1,
+ from_tag, 0);
}
}
}
@@ -216,9 +247,13 @@ static int name_ref(const char *path, const struct object_id *oid, int flags, vo
}
if (o && o->type == OBJ_COMMIT) {
struct commit *commit = (struct commit *)o;
+ int from_tag = starts_with(path, "refs/tags/");
+ if (taggerdate == ULONG_MAX)
+ taggerdate = ((struct commit *)o)->date;
path = name_ref_abbrev(path, can_abbreviate_output);
- name_rev(commit, xstrdup(path), taggerdate, 0, 0, deref);
+ name_rev(commit, xstrdup(path), taggerdate, 0, 0,
+ from_tag, deref);
}
return 0;
}