The logic in an earlier round to detect reflog entries that
point at a broken commit was not sufficient. Just like we do
not trust presense of a commit during pack transfer (we trust
only our refs), we should not trust a commit's presense, even if
the tree of that commit is complete.
A repository that had reflog enabled on some of the refs that
was rewound and then run git-repack or git-prune from older
versions of git can have reflog entries that point at a commit
that still exist but lack commits (or trees and blobs needed for
that commit) between it and some commit that is reachable from
one of the refs.
This revamps the logic -- the definition of "broken commit"
becomes: a commit that is not reachable from any of the refs and
there is a missing object among the commit, tree, or blob
objects reachable from it that is not reachable from any of the
refs. Entries in the reflog that refer to such a commit are
expired.
Since this computation involves traversing all the reachable
objects, i.e. it has the same cost as 'git prune', it is enabled
only when a new option --fix-stale. Fortunately, once this is
run, we should not have to ever worry about missing objects,
because the current prune and pack-objects know about reflogs
and protect objects referred by them.
Unfortunately, this will be absolutely necessary to help people
migrate to the newer prune and repack.
Signed-off-by: Junio C Hamano <junkio@cox.net>
It is unusual for a tag to point at a non-commit, and it is also
unusual for a tag to have reflog, but that is not an error and
we should still prune its reflog entries just as other refs.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Older fsck-objects and prune did not protect commits in reflog
entries, and it is quite possible that a commit still exists in
the repository (because it was in a pack, or something) while
some of its trees and blobs are long gone. Make sure the commit
and its associated tree is complete and expire incomplete ones.
Signed-off-by: Junio C Hamano <junkio@cox.net>
This prepares a place to collect reflog management subcommands,
and implements "expire" action.
$ git reflog expire --dry-run \
--expire=4.weeks \
--expire-unreachable=1.week \
refs/heads/master
The expiration uses two timestamps: --expire and --expire-unreachable.
Entries older than expire time (defaults to 90 days), and entries older
than expire-unreachable time (defaults to 30 days) and records a commit
that has been rewound and made unreachable from the current tip of the
ref are removed from the reflog.
The parameter handling is still rough, but I think the
core logic for expiration is already sound.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Junio C Hamano