[PATCH 2/2] worktree: demonstrate a half-working workaround for auto-gc
While worktrees are marked "experimental", there is really no alternative to using them when trying to work on multiple patch series in parallel.
Sadly, there is still a bug that causes irretrievable data loss caused by worktree's incomplete handling of reflogs (and of the multiple indices of the various worktrees), as this developer can testify a dozen times over.
In the --auto case, we can install a hook that runs before-hand, accumulates all the worktree-specific refs and reflogs and installs them into a very special reflog in the common refs namespace. The only purpose of this stunt is to let gc pick up on those refs and reflogs, of course, and *not* ignore them.
Unfortunately, this still does not address the "git gc" case, but hopefully a real fix will be here some time soon.
Also, if there are simply too many loose objects for Git's liking, it will kick off auto-gc (including the hook, which takes a couple of seconds to run) that subsequently only says that it won't do anything, so the next Git operation will kick off another auto-gc (including the multi-second hook run).
Needless to say: this patch is not actually intended for inclusion, but instead tries to demonstrate the pain and the dear need for a real bug fix (and not another 8 months of buggy Git).
So here is hoping to a timely fix. Cheers.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
t/t6500-gc.sh | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)
Show changes to t/t6500-gc.sh +25 −1
diff --git a/t/t6500-gc.sh b/t/t6500-gc.sh
index e24a4fb611..2f1e52825d 100755
--- a/t/t6500-gc.sh
+++ b/t/t6500-gc.sh
@@ -67,6 +67,30 @@ test_expect_success 'auto gc with too many loose objects does not attempt to cre
test_line_count = 2 new # There is one new pack and its .idx
'
+test_expect_success 'install pre-auto-gc hook for worktrees' '
+ mkdir -p .git/hooks &&
+ write_script .git/hooks/pre-auto-gc <<-\EOF
+ echo "Preserving refs/reflogs of worktrees" >&2 &&
+ dir="$(git rev-parse --git-common-dir)" &&
+ refsdir="$dir/logs/refs" &&
+ rm -f "$refsdir"/preserve &&
+ ident="$(GIT_COMMITTER_DATE= git var GIT_COMMITTER_IDENT)" &&
+ (
+ find "$dir"/logs "$dir"/worktrees/*/logs \
+ -type f -exec cat {} \; |
+ cut -d" " -f1
+ find "$dir"/HEAD "$dir"/worktrees/*/HEAD "$dir"/refs \
+ "$dir"/worktrees/*/refs -type f -exec cat {} \; |
+ grep -v "^ref:"
+ ) 2>/dev/null |
+ sort |
+ uniq |
+ sed "s/.*/& & $ident dummy/" >"$dir"/preserve &&
+ mkdir -p "$refsdir" &&
+ mv "$dir"/preserve "$refsdir"/
+ EOF
+'
+
trigger_auto_gc () {
# This is unfortunately very, very ugly
gdir="$(git rev-parse --git-common-dir)" &&
@@ -76,7 +100,7 @@ trigger_auto_gc () {
git -c gc.auto=1 -c gc.pruneexpire=now -c gc.autodetach=0 gc --auto
}
-test_expect_failure 'gc respects refs/reflogs in all worktrees' '
+test_expect_success 'gc respects refs/reflogs in all worktrees' '
test_commit something &&
git worktree add worktree &&
(
--
2.11.1.windows.1
Johannes Schindelin