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

[Christian Couder <christian.couder@gmail.com>]

On Mon, Jul 11, 2016 at 8:27 PM, Duy Nguyen <pclouds@gmail.com> wrote:
> 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.

Isn't there a way to scan all the current indexes (temp or not) to see
which shared indexes they need?

> 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).

Maybe old linked indexes could be converted after some time to use a
newer shared index, so that we can get rid of the old shared indexes.
That seems safer than just deleting old linked indexes.

Thanks for your review,
Christian.