Merge branch 'jt/avoid-ls-refs'

Over some transports, fetching objects with an exact commit object
name can be done without first seeing the ref advertisements.  The
code has been optimized to exploit this.

* jt/avoid-ls-refs:
  fetch: do not list refs if fetching only hashes
  transport: list refs before fetch if necessary
  transport: do not list refs if possible
  transport: allow skipping of ref listing

1 files changed, 48 insertions, 6 deletions

diff --git a/transport.c b/transport.c
index dd7bd3436c..046b2f6d8c 100644
--- a/transport.c
+++ b/transport.c
@@ -252,8 +252,18 @@ static int connect_setup(struct transport *transport, int for_push)
 	return 0;
 }
 
-static struct ref *get_refs_via_connect(struct transport *transport, int for_push,
-					const struct argv_array *ref_prefixes)
+/*
+ * Obtains the protocol version from the transport and writes it to
+ * transport->data->version, first connecting if not already connected.
+ *
+ * If the protocol version is one that allows skipping the listing of remote
+ * refs, and must_list_refs is 0, the listing of remote refs is skipped and
+ * this function returns NULL. Otherwise, this function returns the list of
+ * remote refs.
+ */
+static struct ref *handshake(struct transport *transport, int for_push,
+			     const struct argv_array *ref_prefixes,
+			     int must_list_refs)
 {
 	struct git_transport_data *data = transport->data;
 	struct ref *refs = NULL;
@@ -268,8 +278,10 @@ static struct ref *get_refs_via_connect(struct transport *transport, int for_pus
 	data->version = discover_version(&reader);
 	switch (data->version) {
 	case protocol_v2:
-		get_remote_refs(data->fd[1], &reader, &refs, for_push,
-				ref_prefixes, transport->server_options);
+		if (must_list_refs)
+			get_remote_refs(data->fd[1], &reader, &refs, for_push,
+					ref_prefixes,
+					transport->server_options);
 		break;
 	case protocol_v1:
 	case protocol_v0:
@@ -283,9 +295,18 @@ static struct ref *get_refs_via_connect(struct transport *transport, int for_pus
 	}
 	data->got_remote_heads = 1;
 
+	if (reader.line_peeked)
+		BUG("buffer must be empty at the end of handshake()");
+
 	return refs;
 }
 
+static struct ref *get_refs_via_connect(struct transport *transport, int for_push,
+					const struct argv_array *ref_prefixes)
+{
+	return handshake(transport, for_push, ref_prefixes, 1);
+}
+
 static int fetch_refs_via_pack(struct transport *transport,
 			       int nr_heads, struct ref **to_fetch)
 {
@@ -320,8 +341,17 @@ static int fetch_refs_via_pack(struct transport *transport,
 	args.server_options = transport->server_options;
 	args.negotiation_tips = data->options.negotiation_tips;
 
-	if (!data->got_remote_heads)
-		refs_tmp = get_refs_via_connect(transport, 0, NULL);
+	if (!data->got_remote_heads) {
+		int i;
+		int must_list_refs = 0;
+		for (i = 0; i < nr_heads; i++) {
+			if (!to_fetch[i]->exact_oid) {
+				must_list_refs = 1;
+				break;
+			}
+		}
+		refs_tmp = handshake(transport, 0, NULL, must_list_refs);
+	}
 
 	switch (data->version) {
 	case protocol_v2:
@@ -703,6 +733,7 @@ static int disconnect_git(struct transport *transport)
 }
 
 static struct transport_vtable taken_over_vtable = {
+	1,
 	NULL,
 	get_refs_via_connect,
 	fetch_refs_via_pack,
@@ -852,6 +883,7 @@ void transport_check_allowed(const char *type)
 }
 
 static struct transport_vtable bundle_vtable = {
+	0,
 	NULL,
 	get_refs_from_bundle,
 	fetch_refs_from_bundle,
@@ -861,6 +893,7 @@ static struct transport_vtable bundle_vtable = {
 };
 
 static struct transport_vtable builtin_smart_vtable = {
+	1,
 	NULL,
 	get_refs_via_connect,
 	fetch_refs_via_pack,
@@ -1227,6 +1260,15 @@ int transport_fetch_refs(struct transport *transport, struct ref *refs)
 	struct ref **heads = NULL;
 	struct ref *rm;
 
+	if (!transport->vtable->fetch_without_list)
+		/*
+		 * Some transports (e.g. the built-in bundle transport and the
+		 * transport helper interface) do not work when fetching is
+		 * done immediately after transport creation. List the remote
+		 * refs anyway (if not already listed) as a workaround.
+		 */
+		transport_get_remote_refs(transport, NULL);
+
 	for (rm = refs; rm; rm = rm->next) {
 		nr_refs++;
 		if (rm->peer_ref &&