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From: "Gerd Möllmann" <gerd.moellmann@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 58158@debbugs.gnu.org
Subject: bug#58158: 29.0.50; [overlay] Interval tree iteration considered harmful
Date: Thu, 29 Sep 2022 09:03:17 +0200	[thread overview]
Message-ID: <m28rm2u0ga.fsf@Mini.fritz.box> (raw)
In-Reply-To: <83h70qhez0.fsf@gnu.org> (Eli Zaretskii's message of "Thu, 29 Sep 2022 09:28:03 +0300")

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Gerd Möllmann <gerd.moellmann@gmail.com>
>> Date: Thu, 29 Sep 2022 07:29:25 +0200
>> 
>> In its current form, interval tree iteration works like this:
>> 
>> 1. Call begin_iteration(T) to iterate over tree T
>> 2. do stuff
>> 3. Call end_iteration(T)
>> 
>> with the following rules:
>> 
>> - Begin_iteration and end_iteration must be paired.
>> 
>> - There can be only one iteration per tree at a time.  Nested iteration
>>   over the same tree is not supported (abort).
>> 
>> - No GC may happen in step 2.  This is because mark_buffer iterates over
>>   buffer overlays.
>> 
>> I think this is an exceedingly dangerous design.
>
> Why, because of "no GC" requirement?  We could ensure that by calling
> inhibit_garbage_collection (if the code doesn't do that already).

It doesn't.

BTW, if anything signals in step 2, so that end_iteration isn't called,
we're also hosed.

> What higher-level operations require "interval tree iteration" that
> you describe?  Which primitives end up doing such iterations?

What has to do with overlays.  To name a few: overlay-at, overlays-in,
next-overlay-change, previous-overlay-change, overlay-lists, ...

I personally think this is a no-go.





  reply	other threads:[~2022-09-29  7:03 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-29  5:29 bug#58158: 29.0.50; [overlay] Interval tree iteration considered harmful Gerd Möllmann
2022-09-29  6:28 ` Eli Zaretskii
2022-09-29  7:03   ` Gerd Möllmann [this message]
2022-09-29  8:08     ` Eli Zaretskii
2022-09-29  9:09       ` Gerd Möllmann
2022-09-29  9:37         ` Eli Zaretskii
2022-09-29 10:05           ` Gerd Möllmann
2022-09-29 10:43             ` Eli Zaretskii
2022-09-29 11:33               ` Gerd Möllmann
2022-09-29 13:10               ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-29 13:23                 ` Eli Zaretskii
2022-09-29 16:48                   ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-29 13:40                 ` Eli Zaretskii
2022-09-29 14:15                 ` Gerd Möllmann
2022-09-29 14:37                   ` Gerd Möllmann
2022-09-29 22:09                     ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-30  5:28                       ` Gerd Möllmann
2022-09-30  6:11                         ` Eli Zaretskii
2022-09-30 11:31                           ` Gerd Möllmann
2022-09-30 18:29                             ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-02  8:06                               ` Gerd Möllmann
2022-10-06 22:36                           ` Dmitry Gutov
2022-10-07 19:47                             ` Eli Zaretskii
2022-10-08 18:50                               ` Dmitry Gutov
2022-10-10  8:10                                 ` Eli Zaretskii
2022-10-11  2:12                                   ` Dmitry Gutov
2022-10-11  6:37                                     ` Eli Zaretskii
2022-09-30 13:25                         ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-30 14:08                           ` Gerd Möllmann
2022-09-30 15:25                             ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-30 16:04                               ` Eli Zaretskii
2022-09-30 17:11                                 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-01  5:06                               ` Gerd Möllmann
2022-10-01 13:54                                 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-02  8:22                                   ` Gerd Möllmann
2022-10-02 16:32                                     ` Andreas Politz
2022-10-03  4:35                                       ` Gerd Möllmann
2022-10-04 10:50                                         ` Andreas Politz
2022-10-01  7:25                               ` Gerd Möllmann
2022-10-01 10:55                                 ` Gerd Möllmann
2022-10-01 14:01                                 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-29 16:40                   ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-01  1:57         ` Richard Stallman
2022-10-01  7:00           ` Eli Zaretskii
2022-10-06 22:26 ` Matt Armstrong
2023-10-06 13:14 ` Gerd Möllmann

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