[Gsoc - 2016] Allow largefiles to be at a different location

[Matt Harbison]

On Mon, 29 Feb 2016 09:57:21 -0500, Piotr Listkiewicz  
<piotr.listkiewicz at gmail.com> wrote:

> Hello,
> I am Piotr Listkiewicz (nicknamed liscju), Computer Science student from
> Cracow in Poland, maybe some of you remembers me from 3.6 Sprint in  
> London.
>
> I am interested in working on "Allow largefiles to be at a different
> location" project, but i need guidance.
>
> First of all ,are there any easy bugs that you would recommend for the
> newcomer for largefile extension for familiarizing myself with the source
> code?

I don't think there are any easy bugs left.  The wrapping done by the  
extension can make things surprisingly complicated.  There are a few  
additional archived (hidden) largefile bugs on bz, but I'm not sure they  
are easy either.

I'm not sure if there's a lot of teaching value in this, but maybe  
consider replacing some of the os.path.* code in largefiles with the vfs  
layer.  There might be enough there that you can see how it looks up files  
in the store, and so forth.  If nothing else, it will give you something  
to do when looking at the code.

     https://www.mercurial-scm.org/wiki/WindowsUTF8Plan

This is more advanced, but would be nice to have in some form:

     https://bz.mercurial-scm.org/show_bug.cgi?id=4242

(My recollection of this is that it wants to verify the files upstream on  
the default path instead of touching anything locally.  I think I end up  
using '--config paths.default=' to force it to verify locally.)

> Secondly , are there any other documents that didn't mentioned at
> https://www.mercurial-scm.org/wiki/SummerOfCode/Ideas2016 that would be
> helpful for familiarizing myself with largefile and project subject in
> general?

The wiki is pretty good at a high level:

     https://www.mercurial-scm.org/wiki/LargefilesExtension

The "magic" of this extension is mostly that it patches up the matcher  
object and hands off to core Mercurial to do most of the work, in most  
situations.  e.g. if the user does `hg add --large foo`, the largefiles  
add() code changes the matcher to contain '.hglf/foo', remove 'foo', and  
then passes it into the core add() function.  (All without touching normal  
file references, if any, of course.)

Is there some specific area you are wondering about?  Maybe look for  
commits that start with 'largefiles:'.  I fixed a series of bugs about a  
year ago or so, and tried to leave enough in the commit comment to explain  
what was wrong or how something works.

Unfortunately, I don't know anything about the wire protocol to help you  
there.

> I would be interested in any piece of advice what should i do, how to  
> start
> working on the project and all relevant information as well.