path: root/builtin/repack.c
diff options
authorJeff King <>2016-06-13 04:36:28 (GMT)
committerJunio C Hamano <>2016-06-14 20:57:42 (GMT)
commit905f27b86ac1f50c6870a064c3b5b9d82c97a145 (patch)
treefa634994e9cc09c9c326c83d593cf6444e39c80e /builtin/repack.c
parent6a7bcb54714c55234a292047ea6bb657bd5ab1b5 (diff)
repack: add --keep-unreachable option
The usual way to do a full repack (and what is done by git-gc) is to run "repack -Ad --unpack-unreachable=<when>", which will loosen any unreachable objects newer than "<when>", and drop any older ones. This is a safer alternative to "repack -ad", because "<when>" becomes a grace period during which we will not drop any new objects that are about to be referenced. However, it isn't perfectly safe. It's always possible that a process is about to reference an old object. Even if that process were to take care to update the timestamp on the object, there is no atomicity with a simultaneously running "repack" process. So while unlikely, there is a small race wherein we may drop an object that is in the process of being referenced. If you do automated repacking on a large number of active repositories, you may hit it eventually, and the result is a corrupted repository. It would be nice to fix that race in the long run, but it's complicated. In the meantime, there is a much simpler strategy for automated repository maintenance: do not drop objects at all. We already have a "--keep-unreachable" option in pack-objects; we just need to plumb it through from git-repack. Note that this _isn't_ plumbed through from git-gc, so at this point it's strictly a tool for people doing their own advanced repository maintenance strategy. Signed-off-by: Jeff King <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'builtin/repack.c')
1 files changed, 9 insertions, 0 deletions
diff --git a/builtin/repack.c b/builtin/repack.c
index 858db38..573e66c 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -146,6 +146,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
int pack_everything = 0;
int delete_redundant = 0;
const char *unpack_unreachable = NULL;
+ int keep_unreachable = 0;
const char *window = NULL, *window_memory = NULL;
const char *depth = NULL;
const char *max_pack_size = NULL;
@@ -175,6 +176,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
N_("write bitmap index")),
OPT_STRING(0, "unpack-unreachable", &unpack_unreachable, N_("approxidate"),
N_("with -A, do not loosen objects older than this")),
+ OPT_BOOL('k', "keep-unreachable", &keep_unreachable,
+ N_("with -a, repack unreachable objects")),
OPT_STRING(0, "window", &window, N_("n"),
N_("size of the window used for delta compression")),
OPT_STRING(0, "window-memory", &window_memory, N_("bytes"),
@@ -196,6 +199,10 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
if (delete_redundant && repository_format_precious_objects)
die(_("cannot delete packs in a precious-objects repo"));
+ if (keep_unreachable &&
+ (unpack_unreachable || (pack_everything & LOOSEN_UNREACHABLE)))
+ die(_("--keep-unreachable and -A are incompatible"));
if (pack_kept_objects < 0)
pack_kept_objects = write_bitmaps;
@@ -239,6 +246,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
} else if (pack_everything & LOOSEN_UNREACHABLE) {
+ } else if (keep_unreachable) {
+ argv_array_push(&cmd.args, "--keep-unreachable");
} else {
argv_array_push(&cmd.env_array, "GIT_REF_PARANOIA=1");