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| author | Ævar Arnfjörð Bjarmason <avarab@gmail.com> | 2021-08-23 13:36:09 +0200 |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2021-08-25 13:27:37 -0700 |
| commit | 7aa7829f754ab722d558e0408ec6f3dbf23ba70f (patch) | |
| tree | 5fc085600d4ed49f1a74adb99feb74f857df46a7 /refs | |
| parent | 6f45ec88d2168013b00b46d8593524ca5b6c0acb (diff) | |
| download | git-7aa7829f754ab722d558e0408ec6f3dbf23ba70f.tar.gz | |
refs/files: add a comment about refs_reflog_exists() call
Add a comment about why it is that we need to check for the the
existence of a reflog we're deleting after we've successfully acquired
the lock in files_reflog_expire(). As noted in [1] the lock protocol
for reflogs is somewhat intuitive.
This early exit code the comment applies to dates all the way back to
4264dc15e19 (git reflog expire, 2006-12-19).
1. https://lore.kernel.org/git/54DCDA42.2060800@alum.mit.edu/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'refs')
| -rw-r--r-- | refs/files-backend.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/refs/files-backend.c b/refs/files-backend.c index 997e021c1c..fbcd0c790b 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -3061,6 +3061,19 @@ static int files_reflog_expire(struct ref_store *ref_store, strbuf_release(&err); return -1; } + + /* + * When refs are deleted, their reflog is deleted before the + * ref itself is deleted. This is because there is no separate + * lock for reflog; instead we take a lock on the ref with + * lock_ref_oid_basic(). + * + * If a race happens and the reflog doesn't exist after we've + * acquired the lock that's OK. We've got nothing more to do; + * We were asked to delete the reflog, but someone else + * deleted it! The caller doesn't care that we deleted it, + * just that it is deleted. So we can return successfully. + */ if (!refs_reflog_exists(ref_store, refname)) { unlock_ref(lock); return 0; |