Re: [PATCH v2 15/16] index-pack: use nr_objects_final as sha1_table size

> 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?