Re: [PATCH v3 14/21] read-cache: touch shared index files when used

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 19, 2017, 19:00 UTC
Message-ID: <xmqqlgu627uj.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <CACsJy8B_xe6RtszPrncvDdSYosNUQxvhcEQ3DO_WO0sepXqvvQ@mail.gmail.com>

Duy Nguyen <pclouds@gmail.com> writes:

Show 21 quoted lines

> On Mon, Jan 9, 2017 at 9:34 PM, Junio C Hamano <gitster@pobox.com> wrote:
>> Duy Nguyen <pclouds@gmail.com> writes:
>>
>>> On Sun, Jan 8, 2017 at 4:46 AM, Junio C Hamano <gitster@pobox.com> wrote:
>>>> Christian Couder <christian.couder@gmail.com> writes:
>>>>
>>>>> So what should we do if freshen_file() returns 0 which means that the
>>>>> freshening failed?
>>>>
>>>> You tell me ;-)  as you are the one who is proposing this feature.
>>>
>>> My answer is, we are not worse than freshening loose objects case
>>> (especially since I took the idea from there).
>>
>> I do not think so, unfortunately.  Loose object files with stale
>> timestamps are not removed as long as objects are still reachable.
>
> But there are plenty of unreachable loose objects, added in index,
> then got replaced with new versions. cache-tree can create loose trees
> too and it's been run more often, behind user's back, to take
> advantage of the shortcut in unpack-trees.

I am not sure if I follow. Aren't objects reachable from the cache-tree in the index protected from gc?

Not that I think freshening would actually fail in a repository where you can actually write into to update the index or its refs to make a difference (iow, even if we make it die() loudly when shared index cannot be "touched" because we are paranoid, no real life usage will trigger that die(), and if a repository does trigger the die(), I think you would really want to know about it).