RE: Uninitialized submodules as symlinks

-----Original Message-----
From: Duy Nguyen [mailto:pclouds@gmail.com]
Sent: Monday, October 17, 2016 5:46 AM
To: David Turner
Cc: Stefan Beller; git@vger.kernel.org
Subject: Re: Uninitialized submodules as symlinks

On Sat, Oct 8, 2016 at 2:59 AM, David Turner [off-list ref]
wrote:

quoted

quoted

-----Original Message-----
From: Stefan Beller [mailto:sbeller@google.com]
Sent: Friday, October 07, 2016 2:56 PM
To: David Turner
Cc: git@vger.kernel.org
Subject: Re: Uninitialized submodules as symlinks

On Fri, Oct 7, 2016 at 11:17 AM, David Turner
[off-list ref]
wrote:

quoted

Presently, uninitialized submodules are materialized in the working
tree as empty directories.

Right, there has to be something, to hint at the user that creating a
file with that path is probably not what they want.

quoted

 We would like to consider having them be symlinks.  Specifically,
we'd like them to be symlinks into a FUSE filesystem which
retrieves files on demand.

We've actually already got a FUSE filesystem written, but we use a
different (semi-manual) means to connect it to the initialized

submodules.

quoted

quoted

So you currently do a

    git submodule init <pathspec>
    custom-submodule make-symlink <pathspec>

?

We do something like

For each initialized submodule: symlink it into the right place in
.../somedir For each uninitialized submodule: symlink from the FUSE
into the right place in .../somedir

So .../somedir has the structure of the git main repo, but is all

symlinks -- some into FUSE, some into the git repo.

quoted

This means that when we initialize (or deinitialize) a submodule, we

need to re-run the linking script.

Do .git files work? If .git files point to somewhere in fuse, I guess you
still have file retrieval on demand. It depends on what files to retrieve
I guess. If you want worktree files, not object database then .git files
won't work because worktree remains in the same filesystem as the super
repo.

Yes, we want worktree files (or even worktree files + built artifacts).