Re: DEVEL: Help with feature implementation

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 18, 2021, 22:54 UTC
Message-ID: <xmqqzh15j1ot.fsf@gitster.c.googlers.com>
In-Reply-To: <C8MIWAN0N50F.235740W7QGT05@localhost>

"Aiyee Bee" <shane.880088.supw@gmail.com> writes:

> Maybe a more practical (but still pretty unusual) solution would be adding
> counters to each commit that tell us how many times they have been traversed
> Through various histories?

The "--show-forkpoints" output shown there at http://ix.io/2Ms6 looks interesting. I think you'd need only 1 bit counter (i.e. "have we visited it only once, or more than once" bit) for your purpose? You traverse from F and Z and the first time you reach C (probably through the F->E->D->C path), you see no SEEN flag on the object so leave the new bit alone, and then when the traverse reaches C again (this time through the Z->Y->C path), while stopping further traversal because you notice C is already SEEN, you mark it with the new bit so record that it has been visited at least twice.