reachable: convert to use odb_for_each_object()

To figure out which objects expired objects we enumerate all loose and
packed objects individually so that we can figure out their respective
mtimes. Refactor the code to instead use `odb_for_each_object()` with a
request that ask for the object mtime instead.

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

Author: pks-t

reachable.c

@@ -191,30 +191,27 @@ static int obj_is_recent(const struct object_id *oid, timestamp_t mtime,
 	return oidset_contains(&data->extra_recent_oids, oid);
 }
 
-static void add_recent_object(const struct object_id *oid,
-			      struct packed_git *pack,
-			      off_t offset,
-			      timestamp_t mtime,
-			      struct recent_data *data)
+static int want_recent_object(struct recent_data *data,
+			      const struct object_id *oid)
 {
-	struct object *obj;
-	enum object_type type;
+	if (data->ignore_in_core_kept_packs &&
+	    has_object_kept_pack(data->revs->repo, oid, KEPT_PACK_IN_CORE))
+		return 0;
+	return 1;
+}
 
-	if (!obj_is_recent(oid, mtime, data))
-		return;
+static int add_recent_object(const struct object_id *oid,
+			     struct object_info *oi,
+			     void *cb_data)
+{
+	struct recent_data *data = cb_data;
+	struct object *obj;
 
-	/*
-	 * We do not want to call parse_object here, because
-	 * inflating blobs and trees could be very expensive.
-	 * However, we do need to know the correct type for
-	 * later processing, and the revision machinery expects
-	 * commits and tags to have been parsed.
-	 */
-	type = odb_read_object_info(the_repository->objects, oid, NULL);
-	if (type < 0)
-		die("unable to get object info for %s", oid_to_hex(oid));
+	if (!want_recent_object(data, oid) ||
+	    !obj_is_recent(oid, *oi->mtimep, data))
+		return 0;
 
-	switch (type) {
+	switch (*oi->typep) {
 	case OBJ_TAG:
 	case OBJ_COMMIT:
 		obj = parse_object_or_die(the_repository, oid, NULL);
@@ -227,77 +224,22 @@ static void add_recent_object(const struct object_id *oid,
 		break;
 	default:
 		die("unknown object type for %s: %s",
-		    oid_to_hex(oid), type_name(type));
+		    oid_to_hex(oid), type_name(*oi->typep));
 	}
 
 	if (!obj)
 		die("unable to lookup %s", oid_to_hex(oid));
-
-	add_pending_object(data->revs, obj, "");
-	if (data->cb)
-		data->cb(obj, pack, offset, mtime);
-}
-
-static int want_recent_object(struct recent_data *data,
-			      const struct object_id *oid)
-{
-	if (data->ignore_in_core_kept_packs &&
-	    has_object_kept_pack(data->revs->repo, oid, KEPT_PACK_IN_CORE))
+	if (obj->flags & SEEN)
 		return 0;
-	return 1;
-}
 
-static int add_recent_loose(const struct object_id *oid,
-			    const char *path, void *data)
-{
-	struct stat st;
-	struct object *obj;
-
-	if (!want_recent_object(data, oid))
-		return 0;
-
-	obj = lookup_object(the_repository, oid);
-
-	if (obj && obj->flags & SEEN)
-		return 0;
-
-	if (stat(path, &st) < 0) {
-		/*
-		 * It's OK if an object went away during our iteration; this
-		 * could be due to a simultaneous repack. But anything else
-		 * we should abort, since we might then fail to mark objects
-		 * which should not be pruned.
-		 */
-		if (errno == ENOENT)
-			return 0;
-		return error_errno("unable to stat %s", oid_to_hex(oid));
+	add_pending_object(data->revs, obj, "");
+	if (data->cb) {
+		if (oi->whence == OI_PACKED)
+			data->cb(obj, oi->u.packed.pack, oi->u.packed.offset, *oi->mtimep);
+		else
+			data->cb(obj, NULL, 0, *oi->mtimep);
 	}
 
-	add_recent_object(oid, NULL, 0, st.st_mtime, data);
-	return 0;
-}
-
-static int add_recent_packed(const struct object_id *oid,
-			     struct packed_git *p,
-			     uint32_t pos,
-			     void *data)
-{
-	struct object *obj;
-	timestamp_t mtime = p->mtime;
-
-	if (!want_recent_object(data, oid))
-		return 0;
-
-	obj = lookup_object(the_repository, oid);
-
-	if (obj && obj->flags & SEEN)
-		return 0;
-	if (p->is_cruft) {
-		if (load_pack_mtimes(p) < 0)
-			die(_("could not load cruft pack .mtimes"));
-		mtime = nth_packed_mtime(p, pos);
-	}
-	add_recent_object(oid, p, nth_packed_object_offset(p, pos), mtime, data);
 	return 0;
 }
 
@@ -307,7 +249,13 @@ int add_unseen_recent_objects_to_traversal(struct rev_info *revs,
 					   int ignore_in_core_kept_packs)
 {
 	struct recent_data data;
-	enum odb_for_each_object_flags flags;
+	unsigned flags;
+	enum object_type type;
+	time_t mtime;
+	struct object_info oi = {
+		.mtimep = &mtime,
+		.typep = &type,
+	};
 	int r;
 
 	data.revs = revs;
@@ -318,16 +266,13 @@ int add_unseen_recent_objects_to_traversal(struct rev_info *revs,
 	oidset_init(&data.extra_recent_oids, 0);
 	data.extra_recent_oids_loaded = 0;
 
-	r = for_each_loose_object(the_repository->objects, add_recent_loose, &data,
-				  ODB_FOR_EACH_OBJECT_LOCAL_ONLY);
-	if (r)
-		goto done;
-
 	flags = ODB_FOR_EACH_OBJECT_LOCAL_ONLY | ODB_FOR_EACH_OBJECT_PACK_ORDER;
 	if (ignore_in_core_kept_packs)
 		flags |= ODB_FOR_EACH_OBJECT_SKIP_IN_CORE_KEPT_PACKS;
 
-	r = for_each_packed_object(revs->repo, add_recent_packed, &data, flags);
+	r = odb_for_each_object(revs->repo->objects, &oi, add_recent_object, &data, flags);
+	if (r)
+		goto done;
 
 done:
 	oidset_clear(&data.extra_recent_oids);