Re: [PATCH] config.txt: clarify core.checkStat = minimal

[Duy Nguyen <pclouds@gmail.com>]

On Fri, Aug 17, 2018 at 5:26 PM Junio C Hamano <gitster@pobox.com> wrote:
> -- >8 --
> Subject: [PATCH] config.txt: clarify core.checkStat
>
> The description of this key does not really tell what the 'minimal'
> mode checks and does not check.  The description for the 'default'
> mode is not much better and just says 'all fields', which is unclear
> and is not even correct (e.g. we do not look at 'atime').
>
> Spell out what are and what are not checked under the 'minimal' mode
> relative to the 'default' mode to help those who want to decide if
> they want to use the 'minimal' mode, also taking information about
> this mode from the commit message of c08e4d5b5c (Enable minimal stat
> checking - 2013-01-22).

Looking good. This does make me want to adjust $GIT_DIR/index format
to optionally not store extra fields if we know we're not going to use
them. But that's a topic for another day.

> Helped-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  Documentation/config.txt | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index ab641bf5a9..933d719137 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -449,10 +449,20 @@ core.untrackedCache::
>         See linkgit:git-update-index[1]. `keep` by default.
>
>  core.checkStat::
> -       Determines which stat fields to match between the index
> -       and work tree. The user can set this to 'default' or
> -       'minimal'. Default (or explicitly 'default'), is to check
> -       all fields, including the sub-second part of mtime and ctime.
> +       When missing or is set to `default`, many fields in the stat
> +       structure are checked to detect if a file has been modified
> +       since Git looked at it.  When this configuration variable is
> +       set to `minimal`, sub-second part of mtime and ctime, the
> +       uid and gid of the owner of the file, the inode number (and
> +       the device number, if Git was compiled to use it), are
> +       excluded from the check among these fields, leaving only the
> +       whole-second part of mtime (and ctime, if `core.trustCtime`
> +       is set) and the filesize to be checked.
> ++
> +There are implementations of Git that do not leave usable values in
> +some fields (e.g. JGit); by excluding these fields from the
> +comparison, the `minimal` mode may help interoperability when the
> +same repository is used by these other systems at the same time.
>
>  core.quotePath::
>         Commands that output paths (e.g. 'ls-files', 'diff'), will
> --
> 2.18.0-666-g63749b2dea
>


-- 
Duy