Re: [RFC/PATCH 8/8] read-cache: unlink old sharedindex files

From: Duy Nguyen <pclouds@gmail.com>
Date: Jul 11, 2016, 18:27 UTC
Message-ID: <CACsJy8BqMFASHf5kJgUh+bd7XG98CafNydE964VJyPXz-emEvA@mail.gmail.com>
In-Reply-To: <20160711172254.13439-9-chriscool@tuxfamily.org>

On Mon, Jul 11, 2016 at 7:22 PM, Christian Couder <christian.couder@gmail.com> wrote:

> Everytime split index is turned on, it creates a "sharedindex.XXXX"
> file in the git directory. This makes sure that old sharedindex
> files are removed after a new one has been created.

Hmm it's one-way link, we don't know how many index files use this shared index file, how can you be sure nobody else will need it? I'm thinking about temporary indexes. If a temp index is created, saved on disk, and use delete the shared index file, the real, main index may become useless. Temp index will most likely replace the main index (git commit) but if a failure happens, we can't fall back.

A safer approach is "touch" the shared index every time a linked index is used, then we can delete shared indexes with old mtime, older than a grace period, in git-prune (or here).

-- 
Duy