Re: [PATCH 4/4] fast-import: only store commit objects

> On 05/03/2013 08:23 PM, Felipe Contreras wrote:
>> On Fri, May 3, 2013 at 12:56 PM, Thomas Rast <trast@inf.ethz.ch> wrote:
>>> Felipe Contreras <felipe.contreras@gmail.com> writes:
>> 
>>> How do we know that this doesn't break any users of fast-import?  Your
>>> comment isn't very reassuring:
>>>
>>>> the vast majority of them will never be used again
>>>
>>> So what's with the minority?
>> 
>> Actually I don't think there's any minority. If the client program
>> doesn't store blobs, the blob marks are not used anyway. So there's no
>> change.
>
> I haven't been following this conversation in detail, but your proposed
> change sounds like something that would break cvs2git [1].  Let me
> explain what cvs2git does and why:
>
> CVS stores all of the revisions of a single file in a single filename,v
> file in rcsfile(5) format.  The revisions are stored as deltas ordered
> so that a single revision can be reconstructed from a single serial read
> of the file.
>
> cvs2git reads each of these files once, reconstructing *all* of the
> revisions for a file in a single go.  It then pours them into a
> git-fast-import stream as blobs and sets a mark on each blob.
>
> Only much later in the conversion does it have enough information to
> reconstruct tree-wide commits.  At that time it outputs git-fast-import
> data (to a second file) defining the git commits and their ancestry.
> The contents are defined by referring to the marks of blobs from the
> first git-fast-import stream file.
>
> This strategy speeds up the conversion *enormously*.
>
> So if I understand correctly that you are proposing to stop allowing
> marks on blob objects to be set and/or referred to later, then I object
> vociferously.