object-file: extract logic to approximate object count

In "builtin/gc.c" we have some logic that checks whether we need to
repack objects. This is done by counting the number of objects that we
have and checking whether it exceeds a certain threshold. We don't
really need an accurate object count though, which is why we only
open a single object directory shard and then extrapolate from there.

Extract this logic into a new function that is owned by the loose object
database source. This is done to prepare for a subsequent change, where
we'll introduce object counting on the object database source level.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 8 insertions, 27 deletions

diff --git a/builtin/gc.c b/builtin/gc.c
index fb329c2cff..a08c7554cb 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -467,37 +467,18 @@ out:
 static int too_many_loose_objects(int limit)
 {
 	/*
-	 * Quickly check if a "gc" is needed, by estimating how
-	 * many loose objects there are.  Because SHA-1 is evenly
-	 * distributed, we can check only one and get a reasonable
-	 * estimate.
+	 * This is weird, but stems from legacy behaviour: the GC auto
+	 * threshold was always essentially interpreted as if it was rounded up
+	 * to the next multiple 256 of, so we retain this behaviour for now.
 	 */
-	DIR *dir;
-	struct dirent *ent;
-	int auto_threshold;
-	int num_loose = 0;
-	int needed = 0;
-	const unsigned hexsz_loose = the_hash_algo->hexsz - 2;
-	char *path;
+	int auto_threshold = DIV_ROUND_UP(limit, 256) * 256;
+	unsigned long loose_count;
 
-	path = repo_git_path(the_repository, "objects/17");
-	dir = opendir(path);
-	free(path);
-	if (!dir)
+	if (odb_source_loose_approximate_object_count(the_repository->objects->sources,
+						      &loose_count) < 0)
 		return 0;
 
-	auto_threshold = DIV_ROUND_UP(limit, 256);
-	while ((ent = readdir(dir)) != NULL) {
-		if (strspn(ent->d_name, "0123456789abcdef") != hexsz_loose ||
-		    ent->d_name[hexsz_loose] != '\0')
-			continue;
-		if (++num_loose > auto_threshold) {
-			needed = 1;
-			break;
-		}
-	}
-	closedir(dir);
-	return needed;
+	return loose_count > auto_threshold;
 }
 
 static struct packed_git *find_base_packs(struct string_list *packs,