fetch-pack: support more than one pack lockfile

Whenever a fetch results in a packfile being downloaded, a .keep file is
generated, so that the packfile can be preserved (from, say, a running
"git repack") until refs are written referring to the contents of the
packfile.

In a subsequent patch, a successful fetch using protocol v2 may result
in more than one .keep file being generated. Therefore, teach
fetch_pack() and the transport mechanism to support multiple .keep
files.

Implementation notes:

 - builtin/fetch-pack.c normally does not generate .keep files, and thus
   is unaffected by this or future changes. However, it has an
   undocumented "--lock-pack" feature, used by remote-curl.c when
   implementing the "fetch" remote helper command. In keeping with the
   remote helper protocol, only one "lock" line will ever be written;
   the rest will result in warnings to stderr. However, in practice,
   warnings will never be written because the remote-curl.c "fetch" is
   only used for protocol v0/v1 (which will not generate multiple .keep
   files). (Protocol v2 uses the "stateless-connect" command, not the
   "fetch" command.)

 - connected.c has an optimization in that connectivity checks on a ref
   need not be done if the target object is in a pack known to be
   self-contained and connected. If there are multiple packfiles, this
   optimization can no longer be done.

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

1 files changed, 5 insertions, 3 deletions

diff --git a/connected.c b/connected.c
index 3135b71..937b4ba 100644
--- a/connected.c
+++ b/connected.c
@@ -43,10 +43,12 @@ int check_connected(oid_iterate_fn fn, void *cb_data,
 
 	if (transport && transport->smart_options &&
 	    transport->smart_options->self_contained_and_connected &&
-	    transport->pack_lockfile &&
-	    strip_suffix(transport->pack_lockfile, ".keep", &base_len)) {
+	    transport->pack_lockfiles.nr == 1 &&
+	    strip_suffix(transport->pack_lockfiles.items[0].string,
+			 ".keep", &base_len)) {
 		struct strbuf idx_file = STRBUF_INIT;
-		strbuf_add(&idx_file, transport->pack_lockfile, base_len);
+		strbuf_add(&idx_file, transport->pack_lockfiles.items[0].string,
+			   base_len);
 		strbuf_addstr(&idx_file, ".idx");
 		new_pack = add_packed_git(idx_file.buf, idx_file.len, 1);
 		strbuf_release(&idx_file);