Re: [External Mail]Re: [PATCH 3/3] parse_object(): check commit-graph when skip_hash set

From: Jeff King <peff@peff.net>
To: 程洋 <chengyang@xiaomi.com>
Cc: "Junio C Hamano" <gitster@pobox.com>,
	"Derrick Stolee" <derrickstolee@github.com>,
	"git@vger.kernel.org" <git@vger.kernel.org>,
	何浩 <hehao@xiaomi.com>, "Xin7 Ma 马鑫" <maxin7@xiaomi.com>,
	石奉兵 <shifengbing@xiaomi.com>, 凡军辉 <fanjunhui@xiaomi.com>,
	王汉基 <wanghanji@xiaomi.com>
Subject: Re: [External Mail]Re: [PATCH 3/3] parse_object(): check commit-graph when skip_hash set
Date: Thu, 8 Sep 2022 14:42:13 -0400	[thread overview]
Message-ID: <Yxo3hXg7AwrqzQO8@coredump.intra.peff.net> (raw)
In-Reply-To: <a87e9eaccf7849fc9eeb10ce7d373db0@xiaomi.com>

On Thu, Sep 08, 2022 at 10:39:08AM +0000, 程洋 wrote:

> > If the caller told us that they don't care about us checking the
> > object hash, then we're free to implement any optimizations that get
> > us the parsed value more quickly. An obvious one is to check the
> > commit graph before loading an object from disk. And in fact, both of
> > the callers who pass in this flag are already doing so before they call
> > parse_object()!
> 
> > So we can simplify those callers, as well as any possible future ones,
> > by moving the logic into parse_object().
> 
> I need to mention that there is serious issue with commit-graph together with partial-clone
> https://lore.kernel.org/git/20220709005227.82423-1-hanxin.hx@bytedance.com/

Yes, though I don't think that changes anything with respect to my
patches. The argument here is simply that if a caller is OK skipping the
hash check, they are OK with using the commit graph, and vice versa.
Until the bug in the linked thread is fixed, it is a good idea to
disable the commit graph. But it does not change the intent of the
calling code.

-Peff