Re: Extending ostree's functionality (adding a metadat index)

[Vivek Dasmohapatra <vivek collabora co uk>]

On Fri, 30 Aug 2013, Colin Walters wrote:

> On Fri, 2013-08-30 at 18:31 +0100, Vivek Dasmohapatra wrote:
>
> > Not quite, because the next commit adds the copy of the sizes from the existing
> > ref into the new commit's size cache, so that committing from multiple refs
> > still produces a size cache.
>
> Ah, I see.  This is a bit magical though in that any other users of the
> API will get invalid sizes unless they know to call that.  I do plan to
> convert gnome-ostree at some point over to directly using the API rather
> than spawning ostree.

Should just happen automatically when preparing a new commit, but
will check the code paths.

> If we to calculate the sizes by walking the tree during commit, that's a
> bit unfortunate in archive-z2 because by default we have to actually
> open each .filez and read the header.  On the other hand, I think it's
> reasonable to assume that someone will toss sufficient RAM at a builder
> that the recent files remain in the page cache.

Right, that's why I wanted to avoid this one.

> So...I think I like the "obviously correct" approach of calculating
> during commit, but if you feel strongly I could be convinced it's worth
> having the more complex code to cache during the commit process.

No strong feelings. I'll have a look at the code later in the week
when I have more time again.