Re: [PATCH 7/8] config: add core.untrackedCache

[Junio C Hamano <gitster@pobox.com>]

Duy Nguyen <pclouds@gmail.com> writes:

> On Thu, Dec 17, 2015 at 2:44 PM, Jeff King <peff@peff.net> wrote:
>> I think we may actually be thinking of the same thing. Naively, I would
>> expect:
>>
>> ..
>>   - if there is cache data in the index but that config flag is not set,
>>     presumably we would not update it (we could even explicitly drop it,
>>     but my understanding is that is not necessary for correctness, but
>>     only as a possible optimization).
>
> No, if somebody adds or removes something from the index, we either
> update or drop it, or it's stale. There's the invalidate_untracked()
> or something in dir.c that we can hook in, check config var and do
> that. And because config is cached recently, it should be a cheap
> operation.

Checking the config may be cheap, but it bothers me a lot that we
have to call that "invalidate" thing every time we go into the
codepath to deal with the index, from code cleanliness point of
view.