On Mon, 9 Sep 2013, Junio C Hamano wrote: > Nicolas Pitre <nico@xxxxxxxxxxx> writes: > > > On Mon, 9 Sep 2013, Nguyễn Thái Ngọc Duy wrote: > > > >> nr_objects in the next patch is used to reflect the number of actual > >> objects in the stream, which may be smaller than the number recorded > >> in pack header. > > > > This highlights an issue that has been nagging me for a while. > > > > We decided to send the final number of objects in the thin pack header > > for two reasons: > > > > 1) it allows to properly size the SHA1 table upfront which already > > contains entries for the omitted objects; > > > > 2) the whole pack doesn't have to be re-summed again after being > > completed on the receiving end since we don't alter the header. > > > > However this means that the progress meter will now be wrong and that's > > terrible ! Users *will* complain that the meter doesn't reach 100% and > > they'll protest for being denied the remaining objects during the > > transfer ! > > > > Joking aside, we should think about doing something about it. I was > > wondering if some kind of prefix to the pack stream could be inserted > > onto the wire when sending a pack v4. Something like: > > > > 'T', 'H', 'I', 'N', <actual_number_of_sent_objects_in_network_order> > > > > This 8-byte prefix would simply be discarded by index-pack after being > > parsed. > > > > What do you think? > > I do not think it is _too_ bad if the meter jumped from 92% to 100% > when we finish reading from the other end ;-), as long as we can > reliably tell that we read the right thing. Sure. but eventually people will complain about this. So while we're about to introduce a new pack format anyway, better think of this little cosmetic detail now when it can be included in the pack v4 capability negociation. > Which brings me to a tangent. Do we have a means to make sure that > the data received over the wire is bit-for-bit correct as a whole > when it is a thin pack stream? When it is a non-thin pack stream, > we have the checksum at the end added by sha1close() which > index-pack.c::parse_pack_objects() can (and does) verify. The trailing checksum is still there. Nothing has changed in that regard. Nicolas