pack-objects: ignore ambiguous object warnings

A git push process runs several processes during its run, but one
includes git send-pack which calls git pack-objects and passes
the known have/wants into stdin using object ids. However, the
default setting for core.warnAmbiguousRefs requires git pack-objects
to check for ref names matching the ref_rev_parse_rules array in
refs.c. This means that every object is triggering at least six
"file exists?" queries.  When there are a lot of refs, this can
add up significantly! I observed a simple push spending three
seconds checking these paths.

The fix here is similar to 4c30d50 "rev-list: disable object/refname
ambiguity check with --stdin".  While the get_object_list() method
reads the objects from stdin, turn warn_on_object_refname_ambiguity
flag (which is usually true) to false.  Just for code hygiene, save
away the original at the beginning and restore it once we are done.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index d1144a8f7ef79f7efa5bf64141a9133cfeee66d1..f703e6df9bee56e46b453cc75be88cb7e6bb3e5f 100644 (file)
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -2988,6 +2988,7 @@ static void get_object_list(int ac, const char **av)
        struct rev_info revs;
        char line[1000];
        int flags = 0;
+       int save_warning;
 
        init_revisions(&revs, NULL);
        save_commit_buffer = 0;
@@ -2996,6 +2997,9 @@ static void get_object_list(int ac, const char **av)
        /* make sure shallows are read */
        is_repository_shallow(the_repository);
 
+       save_warning = warn_on_object_refname_ambiguity;
+       warn_on_object_refname_ambiguity = 0;
+
        while (fgets(line, sizeof(line), stdin) != NULL) {
                int len = strlen(line);
                if (len && line[len - 1] == '\n')
@@ -3022,6 +3026,8 @@ static void get_object_list(int ac, const char **av)
                        die(_("bad revision '%s'"), line);
        }
 
+       warn_on_object_refname_ambiguity = save_warning;
+
        if (use_bitmap_index && !get_object_list_from_bitmap(&revs))
                return;