GNU bug report logs - #77924
31.0.50; [Feature branch] Change marker implementation

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Message #218 received at 77924 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Gerd Möllmann <gerd.moellmann <at> gmail.com>
Cc: pipcet <at> protonmail.com, monnier <at> iro.umontreal.ca, 77924 <at> debbugs.gnu.org,
 stefankangas <at> gmail.com
Subject: Re: bug#77924: 31.0.50; [Feature branch] Change marker implementation
Date: Fri, 25 Apr 2025 13:34:46 +0300

> From: Gerd Möllmann <gerd.moellmann <at> gmail.com>
> Date: Fri, 25 Apr 2025 09:51:05 +0200
> Cc: pipcet <at> protonmail.com, monnier <at> iro.umontreal.ca, 77924 <at> debbugs.gnu.org,
>  stefankangas <at> gmail.com
> 
> 
> Sent from my iPhone
> 
> > On 25. Apr 2025, at 09:45, Eli Zaretskii <eliz <at> gnu.org> wrote:
> > 
> > 
> >> 
> >> From: Gerd Möllmann <gerd.moellmann <at> gmail.com>
> >> Date: Fri, 25 Apr 2025 09:20:55 +0200
> >> Cc: pipcet <at> protonmail.com, monnier <at> iro.umontreal.ca, 77924 <at> debbugs.gnu.org,
> >> stefankangas <at> gmail.com
> >> 
> >> 
> >>>> On 25. Apr 2025, at 09:01, Eli Zaretskii <eliz <at> gnu.org> wrote:
> >>> 
> >>> 
> >>>> 
> >>>> From: Gerd Möllmann <gerd.moellmann <at> gmail.com>
> >>>> Cc: Eli Zaretskii <eliz <at> gnu.org>,  monnier <at> iro.umontreal.ca,
> >>>> 77924 <at> debbugs.gnu.org,  stefankangas <at> gmail.com
> >>>> Date: Thu, 24 Apr 2025 21:53:05 +0200
> >>>> 
> >>>> Pip Cet <pipcet <at> protonmail.com> writes:
> >>>> 
> >>>>> I think what we should do is mimic FOR_EACH_TAIL, and use
> >>>>> FOR_EACH_MARKER like this:
> >>>>> 
> >>>>> struct Lisp_Marker *m;
> >>>>> FOR_EACH_MARKER (b, m)
> >>>>> {
> >>>>>   /* do something with m */
> >>>>> }
> >>>> 
> >>>> We need an if somewhere for the MARKERP, don't we?
> >>> 
> >>> Why is that needed, btw?  Can't we change the representation and/or
> >>> the functions involved to avoid the need for such a test?
> >> 
> >> When markers are freed their entry in the market vector no longer contains a marker reference.
> > 
> > I understand, but why does this need to be tested inside the loop?
> > Can't the loop itself know how many markers are in the vector, and
> > stop when they are exhausted?
> 
> You are thinking of compacting the vector when a marker is freed? Then we would lose the O(1) deletion. As it is the entry is simply pushed on a free list. 

Actually, I thought about maintaining the number of markers in the
vector, so there would be no need to detect that by the MARKERP test.

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