Skip to content

Commit

Permalink
repack: pack objects mentioned by the index
Browse files Browse the repository at this point in the history
When we pack all objects, we use only the objects reachable
from references and reflogs. This misses any objects which
are reachable from the index, but not yet referenced.

By itself this isn't a big deal; the objects can remain
loose until they are actually used in a commit. However, it
does create a problem when we drop packed but unreachable
objects. We try to optimize out the writing of objects that
we will immediately prune, which means we must follow the
same rules as prune in determining what is reachable. And
prune uses the index for this purpose.

This is rather uncommon in practice, as objects in the index
would not usually have been packed in the first place. But
it could happen in a sequence like:

  1. You make a commit on a branch that references blob X.

  2. You repack, moving X into the pack.

  3. You delete the branch (and its reflog), so that X is
     unreferenced.

  4. You "git add" blob X so that it is now referenced only
     by the index.

  5. You repack again with git-gc. The pack-objects we
     invoke will see that X is neither referenced nor
     recent and not bother loosening it.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
  • Loading branch information
Jeff King authored and Junio C Hamano committed Oct 19, 2014
1 parent edfbb2a commit c90f9e1
Show file tree
Hide file tree
Showing 3 changed files with 22 additions and 0 deletions.
8 changes: 8 additions & 0 deletions builtin/pack-objects.c
Original file line number Diff line number Diff line change
Expand Up @@ -2617,6 +2617,7 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
int all_progress_implied = 0;
struct argv_array rp = ARGV_ARRAY_INIT;
int rev_list_unpacked = 0, rev_list_all = 0, rev_list_reflog = 0;
int rev_list_index = 0;
struct option pack_objects_options[] = {
OPT_SET_INT('q', "quiet", &progress,
N_("do not show progress meter"), 0),
Expand Down Expand Up @@ -2663,6 +2664,9 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
{ OPTION_SET_INT, 0, "reflog", &rev_list_reflog, NULL,
N_("include objects referred by reflog entries"),
PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
{ OPTION_SET_INT, 0, "indexed-objects", &rev_list_index, NULL,
N_("include objects referred to by the index"),
PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
OPT_BOOL(0, "stdout", &pack_to_stdout,
N_("output pack to stdout")),
OPT_BOOL(0, "include-tag", &include_tag,
Expand Down Expand Up @@ -2720,6 +2724,10 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
use_internal_rev_list = 1;
argv_array_push(&rp, "--reflog");
}
if (rev_list_index) {
use_internal_rev_list = 1;
argv_array_push(&rp, "--indexed-objects");
}
if (rev_list_unpacked) {
use_internal_rev_list = 1;
argv_array_push(&rp, "--unpacked");
Expand Down
1 change: 1 addition & 0 deletions builtin/repack.c
Original file line number Diff line number Diff line change
Expand Up @@ -209,6 +209,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
argv_array_push(&cmd_args, "--non-empty");
argv_array_push(&cmd_args, "--all");
argv_array_push(&cmd_args, "--reflog");
argv_array_push(&cmd_args, "--indexed-objects");
if (window)
argv_array_pushf(&cmd_args, "--window=%s", window);
if (window_memory)
Expand Down
13 changes: 13 additions & 0 deletions t/t7701-repack-unpack-unreachable.sh
Original file line number Diff line number Diff line change
Expand Up @@ -109,4 +109,17 @@ test_expect_success 'do not bother loosening old objects' '
test_must_fail git cat-file -p $obj2
'

test_expect_success 'keep packed objects found only in index' '
echo my-unique-content >file &&
git add file &&
git commit -m "make it reachable" &&
git gc &&
git reset HEAD^ &&
git reflog expire --expire=now --all &&
git add file &&
test-chmtime =-86400 .git/objects/pack/* &&
git gc --prune=1.hour.ago &&
git cat-file blob :file
'

test_done

0 comments on commit c90f9e1

Please sign in to comment.