From: Jeff King Date: Mon, 13 Jun 2016 04:36:28 +0000 (-0400) Subject: repack: add --keep-unreachable option X-Git-Tag: v2.10.0-rc0~157^2~1 X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/905f27b86ac1f50c6870a064c3b5b9d82c97a145?ds=inline;hp=905f27b86ac1f50c6870a064c3b5b9d82c97a145 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=", which will loosen any unreachable objects newer than "", and drop any older ones. This is a safer alternative to "repack -ad", because "" 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 ---