path: root/builtin/fetch.c
diff options
authorJonathan Tan <>2021-05-04 21:16:01 (GMT)
committerJunio C Hamano <>2021-05-05 01:41:29 (GMT)
commit9c1e657a8fd26fa3ed8d13fb8c796cef8db8b124 (patch)
tree79ed7a1763a89a1be268af86dda6110a2d0c2a1a /builtin/fetch.c
parent6871d0cec62dc12d0c5f7390eee8a80614919578 (diff)
fetch: teach independent negotiation (no packfile)
Currently, the packfile negotiation step within a Git fetch cannot be done independent of sending the packfile, even though there is at least one application wherein this is useful. Therefore, make it possible for this negotiation step to be done independently. A subsequent commit will use this for one such application - push negotiation. This feature is for protocol v2 only. (An implementation for protocol v0 would require a separate implementation in the fetch, transport, and transport helper code.) In the protocol, the main hindrance towards independent negotiation is that the server can unilaterally decide to send the packfile. This is solved by a "wait-for-done" argument: the server will then wait for the client to say "done". In practice, the client will never say it; instead it will cease requests once it is satisfied. In the client, the main change lies in the transport and transport helper code. fetch_refs_via_pack() performs everything needed - protocol version and capability checks, and the negotiation itself. There are 2 code paths that do not go through fetch_refs_via_pack() that needed to be individually excluded: the bundle transport (excluded through requiring smart_options, which the bundle transport doesn't support) and transport helpers that do not support takeover. If or when we support independent negotiation for protocol v0, we will need to modify these 2 code paths to support it. But for now, report failure if independent negotiation is requested in these cases. Signed-off-by: Jonathan Tan <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'builtin/fetch.c')
1 files changed, 26 insertions, 1 deletions
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 0b90de8..a732295 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -82,6 +82,7 @@ static struct string_list server_options = STRING_LIST_INIT_DUP;
static struct string_list negotiation_tip = STRING_LIST_INIT_NODUP;
static int fetch_write_commit_graph = -1;
static int stdin_refspecs = 0;
+static int negotiate_only;
static int git_fetch_config(const char *k, const char *v, void *cb)
@@ -202,6 +203,8 @@ static struct option builtin_fetch_options[] = {
OPT_STRING_LIST(0, "negotiation-tip", &negotiation_tip, N_("revision"),
N_("report that we have only objects reachable from this object")),
+ OPT_BOOL(0, "negotiate-only", &negotiate_only,
+ N_("do not fetch a packfile; instead, print ancestors of negotiation tips")),
OPT_BOOL(0, "auto-maintenance", &enable_auto_gc,
N_("run 'maintenance --auto' after fetching")),
@@ -1986,7 +1989,29 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
- if (remote) {
+ if (negotiate_only) {
+ struct oidset acked_commits = OIDSET_INIT;
+ struct oidset_iter iter;
+ const struct object_id *oid;
+ if (!remote)
+ die(_("must supply remote when using --negotiate-only"));
+ gtransport = prepare_transport(remote, 1);
+ if (gtransport->smart_options) {
+ gtransport->smart_options->acked_commits = &acked_commits;
+ } else {
+ warning(_("Protocol does not support --negotiate-only, exiting."));
+ return 1;
+ }
+ if (
+ gtransport->server_options = &server_options;
+ result = transport_fetch_refs(gtransport, NULL);
+ oidset_iter_init(&acked_commits, &iter);
+ while ((oid = oidset_iter_next(&iter)))
+ printf("%s\n", oid_to_hex(oid));
+ oidset_clear(&acked_commits);
+ } else if (remote) {
if (filter_options.choice || has_promisor_remote())
result = fetch_one(remote, argc, argv, prune_tags_ok, stdin_refspecs);