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bug#22763: 25.1.50; Feature Request -- A faster method to obtain line nu
From: |
Eli Zaretskii |
Subject: |
bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position. |
Date: |
Sun, 07 Feb 2021 20:09:59 +0200 |
> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Eli Zaretskii <eliz@gnu.org>, 22763@debbugs.gnu.org, Keith David
> Bershatsky <esq@lawlist.com>
> Date: Sun, 07 Feb 2021 18:45:51 +0100
>
> 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?
find_newline does the same as display_count_lines: it calls memchr.
But it also maintains a newline cache. If you disable that cache (by
turning of cache-long-scans), you might see a different speedup.
Also, calling forward-line would loop in Lisp, not in C.
- 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, 2021/02/07
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position.,
Eli Zaretskii <=
- 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
- bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position., Eli Zaretskii, 2021/02/07