• Jeff King's avatar
    pack-objects: turn off bitmaps when we see --shallow lines · f7f91086
    Jeff King authored
    Reachability bitmaps do not work with shallow operations,
    because they cache a view of the object reachability that
    represents the true objects. Whereas a shallow repository
    (or a shallow operation in a repository) is inherently
    cutting off the object graph with a graft.
    
    We explicitly disallow the use of bitmaps in shallow
    repositories by checking is_repository_shallow(), and we
    should continue to do that. However, we also want to
    disallow bitmaps when we are serving a fetch to a shallow
    client, since we momentarily take on their grafted view of
    the world.
    
    It used to be enough to call is_repository_shallow at the
    start of pack-objects.  Upload-pack wrote the other side's
    shallow state to a temporary file and pointed the whole
    pack-objects process at this state with "git --shallow-file",
    and from the perspective of pack-objects, we really were
    in a shallow repo.  But since b790e0f6 (upload-pack: send
    shallow info over stdin to pack-objects, 2014-03-11), we do
    it differently: we send --shallow lines to pack-objects over
    stdin, and it registers them itself.
    
    This means that our is_repository_shallow check is way too
    early (we have not been told about the shallowness yet), and
    that it is insufficient (calling is_repository_shallow is
    not enough, as the shallow grafts we register do not change
    its return value). Instead, we can just turn off bitmaps
    explicitly when we see these lines.
    Signed-off-by: default avatarJeff King <peff@peff.net>
    Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
    f7f91086
t5311-pack-bitmaps-shallow.sh 1.04 KB