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author | Jeff King <peff@peff.net> | 2016-06-13 00:36:28 -0400 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2016-06-14 13:57:42 -0700 |
commit | 905f27b86ac1f50c6870a064c3b5b9d82c97a145 (patch) | |
tree | fa634994e9cc09c9c326c83d593cf6444e39c80e /builtin | |
parent | repack: document --unpack-unreachable option (diff) | |
download | tgif-905f27b86ac1f50c6870a064c3b5b9d82c97a145.tar.xz |
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 <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin')
-rw-r--r-- | builtin/repack.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/builtin/repack.c b/builtin/repack.c index 858db38f52..573e66c1b4 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) { argv_array_push(&cmd.args, "--unpack-unreachable"); + } else if (keep_unreachable) { + argv_array_push(&cmd.args, "--keep-unreachable"); } else { argv_array_push(&cmd.env_array, "GIT_REF_PARANOIA=1"); } |