Re: proposal for extending smudge/clean filters with raw file access

From: Junio C Hamano <gitster@pobox.com>
Date: May 12, 2016, 19:01 UTC
Message-ID: <xmqqvb2jf6dg.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20160512182432.GA27427@kitenet.net>

Joey Hess <id@joeyh.name> writes:

Show 14 quoted lines

> I'm using smudge/clean filters in git-annex now, and it's not been an
> entirely smooth fit between the interface and what git-annex wants
> to do.
>
> The clean filter has to consume the whole file content on stdin;
> not reading it all will make git think the clean filter failed.
> But, git-annex often doesn't need to read the whole content of a
> work-tree file in order to clean it.
>
> The smudge filter has to output the whole file content to stdout. But
> git-annex often has the file's content on disk already, and could just
> move it into place in the working tree. This would save CPU and IO and
> often disk space too. But the smudge interface doesn't let git-annex use
> the efficient approach.

The smudge happens to be the last to run, so it is quite true that it can say "Hey Git, I've written it out already".

I didn't check all codepaths to ensure that we won't need the smudged result in core at all, but I am guessing you did so before making this proposal, so in that case I would say this sounds fine.