Re: [RFC] Native access to Git LFS cache

[Lars Schneider <larsxschneider@gmail.com>]

> On 27 Jun 2016, at 18:09, Junio C Hamano <gitster@pobox.com> wrote:
> 
> larsxschneider@gmail.com writes:
> 
>> Unfortunately that fix helps only with cloning. Any local Git operation
>> that invokes the clean/smudge filter (e.g. switching branches) is still
>> slow.
> 
> Do you know where the slowness comes from?  Does Joey's new
> clean/smudge interface help GitLFS?

I am pretty sure the startup time of the external clean/smudge process
causes the slowness and consequently I don't think Joey's patch would help. 
The following tests makes me believe that:

I ran the same test as in my original email using the repo with 15,000 
LFS files. Instead of the LFS binary I use the fast and simple shell 
built-in `true` command:

$ git -c filter.lfs.smudge=true -c filter.lfs.clean=true clone https://github.com/larsxschneider/lfstest-manyfiles.git
$ cd lfstest-manyfiles/
$ time git -c filter.lfs.smudge=true -c filter.lfs.clean=true checkout removed-files

real	0m47.030s
user	0m29.521s
sys	0m16.993s

It still takes 47 seconds to switch the branch. Does this test prove my
point or do you see a flaw in the test?


> You are not likely to get anything that knows that a blob object may
> be named as anything other than SHA-1("blob <len>" + <contents>) to
> Git core.  The remote-object-store idea that was floated by Peff and
> Christian started running with at least maintains that object naming
> property and has a better chance of interacting better with the core,
> but LFS, Annex or anything that would not preserve the object naming
> would not.
> 
> Personally, I view a surrogate blob left by LFS in the tree object
> and filtered via clean/smudge a "smarter" kind of symbolic link that
> points outside what Git controls.  The area outside what Git
> controls is left to be managed by whatever the add-on does; Git
> shouldn't even be aware of how they are structured and/or managed.

I understand and somewhat anticipated your point of view. I will try
to find a less intrusive solution.

@Christian/Peff: 
Is there a place to look for more info about your remote-object-store idea? 

Thanks,
Lars