[RFC PATCH 3/4] name-rev: check if a commit should be named before naming it

[Alban Gruin <alban.gruin@gmail.com>]

Until now, name_rev() named every commit it found, even it the name
would ultimately be unused.

This makes name_rev() take a commit_list and check if the commit it wants
to name is part of the list.  If it is, the commit is named, and
name_rev() signals to its caller that the name should not be freed.  If
it is not, the commit is left unnamed.  In this case, the name can still
be used by the first descendant of this commit (or one of its descendants).

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
---
 builtin/name-rev.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/builtin/name-rev.c b/builtin/name-rev.c
index 0719a9388d..2f89ed50a1 100644
--- a/builtin/name-rev.c
+++ b/builtin/name-rev.c
@@ -80,7 +80,7 @@ static int is_better_name(struct rev_name *name,
 static int name_rev(struct commit *commit,
 		const char *tip_name, timestamp_t taggerdate,
 		int generation, int distance, int from_tag,
-		int deref)
+		int deref, struct commit_list *commits)
 {
 	struct rev_name *name = get_commit_rev_name(commit);
 	struct commit_list *parents;
@@ -107,12 +107,18 @@ static int name_rev(struct commit *commit,
 	} else if (is_better_name(name, tip_name, taggerdate,
 				  generation, distance, from_tag)) {
 copy_data:
-		name->tip_name = tip_name;
+		if (commit_list_contains(commits, commit) ||
+		    commit_list_count(commits) == 0) {
+			name->tip_name = tip_name;
+			free_alloc = 0;
+		} else {
+			name->tip_name = NULL;
+		}
+
 		name->taggerdate = taggerdate;
 		name->generation = generation;
 		name->distance = distance;
 		name->from_tag = from_tag;
-		free_alloc = 0;
 	} else {
 		free(to_free);
 		return 1;
@@ -135,12 +141,12 @@ static int name_rev(struct commit *commit,
 
 			if (name_rev(parents->item, new_name, taggerdate, 0,
 				      distance + MERGE_TRAVERSAL_WEIGHT,
-				      from_tag, 0))
+				      from_tag, 0, commits))
 				free(new_name);
 		} else {
 			free_alloc &= name_rev(parents->item, tip_name, taggerdate,
 					       generation + 1, distance + 1,
-					       from_tag, 0);
+					       from_tag, 0, commits);
 		}
 	}
 
@@ -279,7 +285,7 @@ static int name_ref(const char *path, const struct object_id *oid, int flags, vo
 			taggerdate = ((struct commit *)o)->date;
 		path = name_ref_abbrev(path, can_abbreviate_output);
 		name_rev(commit, xstrdup(path), taggerdate, 0, 0,
-			 from_tag, deref);
+			 from_tag, deref, NULL);
 	}
 	return 0;
 }
-- 
2.20.1