connected: verify promisor-ness of partial clone

Commit dfa33a298d ("clone: do faster object check for partial clones",
2019-04-21) optimized the connectivity check done when cloning with
--filter to check only the existence of objects directly pointed to by
refs. But this is not sufficient: they also need to be promisor objects.
Make this check more robust by instead checking that these objects are
promisor objects, that is, they appear in a promisor pack.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/clone.c

@@ -673,7 +673,7 @@ static void update_remote_refs(const struct ref *refs,
 			       const char *msg,
 			       struct transport *transport,
 			       int check_connectivity,
-			       int check_refs_only)
+			       int check_refs_are_promisor_objects_only)
 {
 	const struct ref *rm = mapped_refs;
 
@@ -682,7 +682,8 @@ static void update_remote_refs(const struct ref *refs,
 
 		opt.transport = transport;
 		opt.progress = transport->progress;
-		opt.check_refs_only = !!check_refs_only;
+		opt.check_refs_are_promisor_objects_only =
+			!!check_refs_are_promisor_objects_only;
 
 		if (check_connected(iterate_ref_map, &rm, &opt))
 			die(_("remote did not send all necessary objects"));

connected.c

@@ -52,19 +52,28 @@ int check_connected(oid_iterate_fn fn, void *cb_data,
 		strbuf_release(&idx_file);
 	}
 
-	if (opt->check_refs_only) {
+	if (opt->check_refs_are_promisor_objects_only) {
 		/*
 		 * For partial clones, we don't want to have to do a regular
 		 * connectivity check because we have to enumerate and exclude
 		 * all promisor objects (slow), and then the connectivity check
 		 * itself becomes a no-op because in a partial clone every
 		 * object is a promisor object. Instead, just make sure we
-		 * received the objects pointed to by each wanted ref.
+		 * received, in a promisor packfile, the objects pointed to by
+		 * each wanted ref.
 		 */
 		do {
-			if (!repo_has_object_file_with_flags(the_repository, &oid,
+			struct packed_git *p;
-							     OBJECT_INFO_SKIP_FETCH_OBJECT))
+
-				return 1;
+			for (p = get_all_packs(the_repository); p; p = p->next) {
+				if (!p->pack_promisor)
+					continue;
+				if (find_pack_entry_one(oid.hash, p))
+					goto promisor_pack_found;
+			}
+			return 1;
+promisor_pack_found:
+			;
 		} while (!fn(cb_data, &oid));
 		return 0;
 	}

connected.h

@@ -48,12 +48,13 @@ struct check_connected_options {
 	unsigned is_deepening_fetch : 1;
 
 	/*
-	 * If non-zero, only check the top-level objects referenced by the
+	 * If non-zero, only check that the top-level objects referenced by the
-	 * wanted refs (passed in as cb_data). This is useful for partial
+	 * wanted refs (passed in as cb_data) are promisor objects. This is
-	 * clones, where enumerating and excluding all promisor objects is very
+	 * useful for partial clones, where enumerating and excluding all
-	 * slow and the commit-walk itself becomes a no-op.
+	 * promisor objects is very slow and the commit-walk itself becomes a
+	 * no-op.
 	 */
-	unsigned check_refs_only : 1;
+	unsigned check_refs_are_promisor_objects_only : 1;
 };
 
 #define CHECK_CONNECTED_INIT { 0 }