Re: [PATCH] {fetch,receive}-pack: drop unpack-objects, delay loosing objects until the end

On Sun, Sep 1, 2013 at 11:05 PM, Nguyễn Thái Ngọc Duy [off-list ref] wrote:

Current code peaks into the transfered pack's header, if the number of

s/peaks/peeks/

objects is under a limit, unpack-objects is called to handle the rest,
otherwise index-pack is. This patch makes fetch-pack use index-pack
unconditionally, then turn objects loose and remove the pack at the
end. unpack-objects is deprecated and may be removed in future.

There are a few reasons for this:

 - down to two code paths to maintain regarding pack reading
   (sha1_file.c and index-pack.c). When .pack v4 comes, we don't need
   to duplicate work in index-pack and unpack-objects.

 - the number of objects should not be the only indicator for
   unpacking. If there are a few large objects in the pack, the pack
   should be kept anyway. Keeping the pack lets us examine the whole
   pack later and make a better decision.

 - by going through index-pack first, then unpack, we pay extra cost
   for completing a thin pack into a full one. But compared to fetch's
   total time, it should not be noticeable because unpack-objects is
   only called when the pack contains a small number of objects.

 - unpack-objects does not support streaming large blobs. Granted
   force_object_loose(), which is used by this patch, does not either.
   But it'll be easier to do so because sha1_file.c interface supports
   streaming.

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>