From: Lars Ingebrigtsen <larsi@gnus.org>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: 22763@debbugs.gnu.org, Keith David Bershatsky <esq@lawlist.com>
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 [thread overview]
Message-ID: <8735y721mb.fsf@gnus.org> (raw)
In-Reply-To: <87h7mn22ls.fsf@gnus.org> (Lars Ingebrigtsen's message of "Sun, 07 Feb 2021 18:45:51 +0100")
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
next prev parent reply other threads:[~2021-02-07 18:07 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-22 2:42 bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position Keith David Bershatsky
2016-02-22 16:06 ` Eli Zaretskii
2021-02-07 15:07 ` Lars Ingebrigtsen
2021-02-07 15:44 ` Lars Ingebrigtsen
2021-02-07 16:07 ` Lars Ingebrigtsen
2021-02-07 17:40 ` Stefan Monnier
2021-02-07 17:45 ` Lars Ingebrigtsen
2021-02-07 18:07 ` Lars Ingebrigtsen [this message]
2021-02-07 18:09 ` Eli Zaretskii
2021-02-07 18:14 ` Lars Ingebrigtsen
2021-02-07 18:23 ` Lars Ingebrigtsen
2021-02-07 19:02 ` Eli Zaretskii
2021-02-07 19:06 ` Eli Zaretskii
2021-02-07 19:25 ` Lars Ingebrigtsen
2021-02-07 19:34 ` Lars Ingebrigtsen
2021-02-07 19:43 ` Eli Zaretskii
2021-02-07 19:42 ` Eli Zaretskii
2021-02-07 19:46 ` Lars Ingebrigtsen
2021-02-07 19:52 ` Eli Zaretskii
2021-02-07 21:52 ` Lars Ingebrigtsen
2021-02-07 21:58 ` Lars Ingebrigtsen
2021-02-08 3:34 ` Eli Zaretskii
2021-02-07 22:09 ` Philipp
2021-02-07 20:37 ` Stefan Monnier
2021-02-07 20:42 ` Lars Ingebrigtsen
2021-02-07 20:50 ` Eli Zaretskii
2021-02-07 21:36 ` Lars Ingebrigtsen
2021-02-08 15:04 ` Eli Zaretskii
2021-02-09 2:17 ` Katsumi Yamaoka
2021-02-09 7:13 ` Lars Ingebrigtsen
2021-05-19 23:55 ` Ben Levy via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-05-20 6:45 ` Eli Zaretskii
2021-05-20 7:27 ` Andreas Schwab
2021-05-20 7:35 ` Ben Levy via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-05-20 9:08 ` Eli Zaretskii
2021-05-20 9:03 ` Eli Zaretskii
2021-05-20 19:53 ` Ben Levy via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-05-20 20:09 ` Eli Zaretskii
2021-05-20 20:40 ` Ben Levy via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-05-21 5:46 ` Eli Zaretskii
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