[RFC/PATCH 2/2] repack: Remove stale .keep files before repacking

[Johan Herland <johan@herland.net>]

When a push is aborted, receive-pack sometimes leave stale .keep files in the
objects/pack/ directory. Fortunately, these files are easily identified by
looking at their contents, which is of the form:

  receive-pack $pid on $host

By recognizing this format we can determine whether the .keep file is stale,
and can be safely deleted: If the $host part matches the current hostname,
and there is currently no process with $pid, we can safely assume that the
.keep file no longer refers to a running receive-pack process, and deleting
it should be perfectly safe.
---

On Thursday 31 March 2011, Jeff King wrote:
> On Thu, Mar 31, 2011 at 12:46:25PM +0200, Johan Herland wrote:
> > 3. Do I need to scan for and remove stale .keep files in a cron job
> > 
> >    in order to keep repos healthy and clonable?
> 
> If we fix (1), then hopefully it is not as much of an issue. But
> probably "git gc" should clean up stale ones after a while.

This patch tries to automatically remove stale .keep files. However,
it's still work-in-progress, as I don't know how to portably (a) ask
for the current hostname (so that I can compare it to the one in the
.keep file), or (b) test for whether a given PID is running on the
system (to determine whether the receive-pack process that wrote the
.keep file is still alive).

Feedback appreciated.


...Johan


 git-repack.sh |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/git-repack.sh b/git-repack.sh
index 624feec..f59e4c4 100755
--- a/git-repack.sh
+++ b/git-repack.sh
@@ -56,6 +56,18 @@ PACKTMP="$PACKDIR/.tmp-$$-pack"
 rm -f "$PACKTMP"-*
 trap 'rm -f "$PACKTMP"-*' 0 1 2 3 15
 
+HOST=`hostname || echo "localhost"` # FIXME: Portability?
+for e in `cd "$PACKDIR" && find . -type f -name '*.keep' | sed -e 's/^\.\///'`
+do
+	cat "$PACKDIR/$e" | if read word pid on host
+	then
+		test "$word" = "receive-pack" -a "$on" = "on" -a "$host" = "$HOST" || continue
+		ps -p "$pid" > /dev/null && continue # FIXME: Portability?
+		rm -f "$PACKDIR/$e"
+		say Removed stale keep file $PACKDIR/$e.
+	fi
+done
+
 # There will be more repacking strategies to come...
 case ",$all_into_one," in
 ,,)
-- 
1.7.4