On Mon, Feb 7, 2022 at 10:48 AM Han-Wen Nienhuys <hanwen@xxxxxxxxxx> wrote: > > On Fri, Feb 4, 2022 at 12:06 AM Junio C Hamano <gitster@xxxxxxxxx> wrote: > > > > Han-Wen Nienhuys <hanwen@xxxxxxxxxx> writes: > > > > > Technically, the only obstacle I see is that we'd need to treat an > > > existence entry especially for the purpose of compaction/gc: we can > > > discard older entries, but we shouldn't discard the existence bit, no > > > matter how old it is. > > > > I was hoping that we already have a type of block that can be used > > to record an attribute on the ref (other than its value) and it > > would be just the matter of stealing one unused bit from such a > > record per ref to say "when answering 'does this ref have reflog?' > > say yes even when there is no log record for that refname". Or the > > table format is extensible enough that we can add such a block > > without breaking existing clients. > > That place doesn't exist, unfortunately, but even if it did, having a > special reflog entry indicating existence is a better solution all > around, I think. A separate per-ref bit allows for data > inconsistencies: what if the bit says "there is no reflog", but we > actually do have reflog entries in the 'g' section? > > It also has less chances of creating complicated control flows > (especially in JGit which wasn't designed for this bit from the > start): the tables have to be written in lexicographic order, so you > only can write this bit after you know if reflog entries were written > for a certain ref. Correction. I wish the table blocks were written in lexicographic order, but they are written in order 'g', ['i',] 'o', ['i'], 'g', ['i']. Since the 'g' block is last within a table, we could add a new section at the end. My point that this is considerable work to think through how to make this work with JGit still stands, though. -- Han-Wen Nienhuys - Google Munich I work 80%. Don't expect answers from me on Fridays. -- Google Germany GmbH, Erika-Mann-Strasse 33, 80636 Munich Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
