Re: [PATCH 01/10] doc: about submodule support with multiple worktrees

From: Stefan Beller <sbeller@google.com>
To: "Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>
Cc: git <git@vger.kernel.org>,
	"Tomasz Śniatowski" <tsniatowski@vewd.com>,
	"Jonathan Nieder" <jrnieder@gmail.com>,
	"Marc Branchaud" <marcnarc@xiplink.com>,
	"Junio C Hamano" <gitster@pobox.com>
Subject: Re: [PATCH 01/10] doc: about submodule support with multiple worktrees
Date: Wed, 16 Jan 2019 14:06:24 -0800	[thread overview]
Message-ID: <CAGZ79kYWi0EDr-XvoXm=-Oo-_9FiieNHbWzA5o8TiirLw+xXBg@mail.gmail.com> (raw)
In-Reply-To: <20190116103159.9305-2-pclouds@gmail.com>

> The third problem is a big and complicaed one. Submodule clones

complicated

> (inside the superproject) are per-worktree. So if you have two
> worktrees, and these have one submodule, you need space for _two_
> clones. This is definitely not elegant. The tenative plan is to move

tentative?

> clones from $GIT_COMMON_DIR/worktrees/X/modules to
> $GIT_COMMON_DIR/common/modules.

... from the submodule side of things this is big problem,
as the submodule is usually assumed at $GIT_DIR/modules/<name>
(I think we have not been strict in $GIT_DIR $GIT_COMMON_DIR
in the submodule code)

So the plan is to neither use
$GIT_COMMON_DIR/worktrees/X/modules/Y
$GIT_COMMON_DIR/modules/Y/worktrees/X
but to create a new third location at
$GIT_COMMON_DIR/common/modules
to which either new submodule worktrees
or superproject worktrees that happen to have this submodule
can point to?

>
> The latter directory is shared across all worktrees. Once we keep the
> clone in a common place, the submodule's worktree can be created and
> managed with git-worktree[1].

So even when the user has never heard of worktrees, the internal structure
will be worktree oriented, the common dir in common/modules/Y and in
$GIT_DIR/modules/Y we could just have a worktree git dir?

> Another good point about this approach is we could finally safely
> allow "git worktree remove" to work with submodules. With current
> solution, removing $GIT_COMMON_DIR/worktrees/X directory means also
> removing potentially precious clones inside the "modules" subdir.

yup, very sensible.

I like this approach very much.