Re: branch --contains / tag --merged inconsistency

From: Ferenc Wágner <wferi@niif.hu>
Date: Apr 28, 2018, 06:27 UTC
Message-ID: <877eor6e2i.fsf@lant.ki.iif.hu>
In-Reply-To: <20180427160344.12724-1-szeder.dev@gmail.com>

SZEDER Gábor <szeder.dev@gmail.com> writes:

Show 9 quoted lines

> The commit pointed to by the tag Pacemaker-0.6.1 and its parent have a
> serious clock skew, i.e. they are a few months older than their parents:
> [...]
> (branch|tag|describe|...) (--contains|--merged) use the commit timestamp
> information as a heuristic to avoid traversing parts of the history,
> which makes these operations, especially on big histories, an order of
> magnitude or two faster.  Yeah, commit timestamps can't always be
> trusted, but skewed commits are rare, and skewed commits with this much
> skew are even rarer.

Szia Gábor,

Thank you very much for the explanation! Good to know there's no serious problem or misunderstanding here, but a conscious algorithmic choice being fooled by clock skew. I wonder if there's a way such clock skew can appear without actual committer clocks being off by months...

> FWIW, much work is being done on a cached commit graph including commit
> generation numbers, which will solve this issue both correctly and more
> efficiently.  Perhaps it will already be included in the next release.

Wonderful news, thanks for sharing it!

-- 
Regards,
Feri