[PATCH 2/2] fetch: forgo full connectivity check if --filter

[Jonathan Tan <jonathantanmy@google.com>]

If a filter is specified, we do not need a full connectivity check on
the contents of the packfile we just fetched; we only need to check that
the objects referenced are promisor objects.

This significantly speeds up fetches into repositories that have many
promisor objects, because during the connectivity check, all promisor
objects are enumerated (to mark them UNINTERESTING), and that takes a
significant amount of time.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
---
For example, a local fetch was sped up from 6.63s to 3.39s. The bulk of
the remaining time is spent in yet another connectivity check
(fetch_refs -> check_exist_and_connected) prior to the fetch - that will
hopefully be done in a subsequent patch.
---
 builtin/fetch.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index b4c6d921d0..6fb50320eb 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -906,8 +906,17 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
 		url = xstrdup("foreign");
 
 	if (!connectivity_checked) {
+		struct check_connected_options opt = CHECK_CONNECTED_INIT;
+
+		if (filter_options.choice)
+			/*
+			 * Since a filter is specified, objects indirectly
+			 * referenced by refs are allowed to be absent.
+			 */
+			opt.check_refs_are_promisor_objects_only = 1;
+
 		rm = ref_map;
-		if (check_connected(iterate_ref_map, &rm, NULL)) {
+		if (check_connected(iterate_ref_map, &rm, &opt)) {
 			rc = error(_("%s did not send all necessary objects\n"), url);
 			goto abort;
 		}
-- 
2.25.0.rc1.283.g88dfdc4193-goog