Re: [PATCH 00/23] Preliminary pack v4 support

From: Duy Nguyen <pclouds@gmail.com>
Date: Aug 28, 2013, 03:06 UTC
Message-ID: <CACsJy8DAeeUrkUw6A28suLq4VoHjt-k3Wd8SLHWcjxr85A0c2g@mail.gmail.com>
In-Reply-To: <alpine.LFD.2.03.1308272241470.14472@syhkavp.arg>

On Wed, Aug 28, 2013 at 9:58 AM, Nicolas Pitre <nico@fluxnic.net> wrote:

Show 6 quoted lines

>> But what if we store
>> appended objects in OBJ_REF_DELTA format where base ref is empty
>> tree/commit and cached by sha1_file.c?
>
> I don't follow you here.  Missing objects need to be added to the pack,
> they can't be cached anywhere.

I use ref-delta as an alternate escape hatch to store missing commits and trees in unparsed format. In order to do that, I need a base ref SHA-1 and we can create and store SHA-1 of empty commit and emptry tree in sha1_file.c (because empty commit is not in a valid format and can't be parsed and stored in v3). So the result pack is still "thin" but it should only lack at most two objects: empty commit and empty tree. Thinking again this is much uglier than escape hatches to v3 tables..

-- 
Duy