Re: [PATCH/POC 3/7] setup.c: add split-repo support to .git files

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 13, 2013, 18:30 UTC
Message-ID: <xmqqiousr4bg.fsf@gitster.dls.corp.google.com>
In-Reply-To: <1386771333-32574-4-git-send-email-pclouds@gmail.com>

Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:

Show 7 quoted lines

> If a .git file contains
>
> gitsuper: <path>
> gitdir: <id>
>
> then we set GIT_SUPER_DIR to <path> and GIT_DIR to
> $GIT_SUPER_DIR/repos/<id>.

I initially thought: "what is with that complexity? isn't it just the matter of replacing 'gitdir: <path>' with 'gitsuper: <path>' stored in the file .git???"

Until I realized that there is nowhere to keep per-workdir data if we only had .git as a pointer, and that is why you have that <id> thing. It would have helped me avoid that confusion if the above description was followed by:

    The latter, $GIT_SUPER_DIR/repos/<id>, is a directory,
    underneath which per-work-dir items like index, HEAD, logs/HEAD
    (what else?) reside.

or something like that. And $GIT_SUPER_DIR/repos/*/HEAD, especially when they are detached, plus $GIT_SUPER_DIR/repos/*/index, will work as the starting point of object reachability scanning when running repack, fsck, etc.

A few more random thoughts...

 - Reusing "gitdir:" for this purpose is not advisable; use a
   different name.  This <id> is used to identify a workdir, so
   perhaps "gitworkdir: <id>" might be a better name;

 - Do we want to record where the working tree directory is in
   $GIT_SUPER_DIR/repos/<id> somewhere?  Would it help to have such
   a record?

 - How would this interact with core.worktree in .git/config of that
   "super" repository?