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bug#22763: 25.1.50; Feature Request -- A faster method to obtain line nu
From: |
Lars Ingebrigtsen |
Subject: |
bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position. |
Date: |
Sun, 07 Feb 2021 19:07:08 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) |
Lars Ingebrigtsen <larsi@gnus.org> writes:
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
>> Why is it faster?
>>
>> Is it still always Θ(N) just with a smaller constant (if so, what makes
>> the constant smaller), or does it benefit from some kind of caching
>> (which I fail to see in the code) such that it's O(N) sometimes but much
>> faster other times (and if so, what are the cases that are sped up)?
>
> There's no caching. I guess find_newline is just slow compared to
> display_count_lines? (How many of these functions do we have in the C
> layer, anyway?)
Oh, I see that find_newline has a lot of caching going on, and the logic
isn't... quite... obvious. I guess it's possible there may be cases
where the new implementation is slower, then? I'm not sure how to
measure that, though -- it takes 10x more time to call the old
`line-number-at-pos' ten times, so if the function is supposed to cache
something, it's not doing that.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Lars Ingebrigtsen, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Lars Ingebrigtsen, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Lars Ingebrigtsen, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Stefan Monnier, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Lars Ingebrigtsen, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position.,
Lars Ingebrigtsen <=
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Eli Zaretskii, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Lars Ingebrigtsen, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Lars Ingebrigtsen, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Eli Zaretskii, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Eli Zaretskii, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Lars Ingebrigtsen, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Lars Ingebrigtsen, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Eli Zaretskii, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Eli Zaretskii, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Lars Ingebrigtsen, 2021/02/07