From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 01 Feb 2017 23:50:50 GMT
Subject: Re: git commit results in many lstat()s
Message-ID: <xmqq60ktmpwl.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <DA0A42D68346B1469147552440A645039A9C57D6@ORSMSX115.amr.corp.intel.com>

"Gumbel, Matthew K" <matthew.k.gumbel@intel.com> writes:

> "Junio C Hamano" <jch2355@gmail.com> writes:
>> There probably are other things that can be optimized.
>
> Yes, I think that when the user passes --only flag to git-commit, then git does not
> need to call refresh_cache() in prepare_index() in builtin/commit.c.
>
> I may experiment with that. Do you see any downside or negative side-effects?

There may be other fallouts, but one that immediately comes to mind
is that it may break pre-commit hook.

When we get "--only", we prepare an temporary index to create the
commit out of, and give it to the pre-commit hook.  The hook expects
that the cached stat information is up-to-date, iow, it does not
have to do 'update-index --refresh' before using plumbing commands
like "diff-index" to do its own inspection of the working tree.