Jakub Narebski <jnareb@xxxxxxxxx> writes:
> Jakub Narebski <jnareb@xxxxxxxxx> writes:
>> Stefan Beller <sbeller@xxxxxxxxxx> writes:
> [...]
>>> How would this impact creation of a commit?
>>>
>>> The current generation numbers can be lazily updated or not
>>> updated at all. In my understanding of the maximum generation
>>> numbers, a new commit would make these maximum generation
>>> numbers invalid (i.e. they have to be recomputed).
> [...]
>>> For the V2 maximum generation numbers, would we need to
>>> rewrite the numbers for all commits once we recompute them?
>>> Assuming that is true, it sounds like the benchmark doesn't
>>> cover the whole costs associated with V2, which is why the
>>> exceptional performance can be explained.
>>
>> Let's check it using a simple example
>>
>> First, (minimum) parent-based generation numbers before and after
>> extending the commit graph:
>>
>> 1 2 3 4 5 6 7 new
>> 1 2 3 4 5 - - old
>> .---.-----.---.-----.---*---*
>> \
>> \ 3 4 5 6 new
>> \ 3 4 5 6 old
>> \-.---.-----.---.
>> \
>> \ 5 new
>> \ - old
>> \-*
>
> Let me check yet another idea, using (minimum) parent-based V0 generation
> numbers (counting distance from the sink / root) as a starting number
> for source / heads commits.
[...]
> [...] but let's check another example
>
> 1 2 3 4 5 6 7 8 9 new
> 1 2 3 4 5 6 7 8 - old
> .---.-----.---.---.---.-----.---.---*
> \ /
> \ 3 4 / 5 6 7 8 new
> \ 5 6 / - - - - old
> \-.---.---------/---*---*---*---*
But let's do this correctly.
1 2 3 4 5 6 7 8 9 new
1 2 3 4 5 6 7 8 - old
.---.-----.---.------.---.-----.---.---*
\ /
\ 3 4 / new
\ 5 6 / old
\-.---.------------/
\
\ 5 6 7 8 new
\ - - - - old
\--*---*-----*---*
Well, it looks as if I draw it incorrectly, but performed calculations
right. You may need to modify / change some data, but it looks as if it
is not that much of a problem.
The new version of the maximum generation numbers looks like it gives
the same results as generation numbers for the "longest" path, and
update may affect only the side-branches that were added to. All
branches merged into the trunk, and not added to should be safe with
respect to updating.
Can anyone here prove a thing about update of those modified maximum
generation numbers? Thanks in advance.
Best,
--
Jakub Narębski
