bug#69784: 29.2; Proced auto update should only update visible buffers

[Rahguzar via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Hi Eli,

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Wed, 13 Mar 2024 22:00:17 +0100
>> From:  Rahguzar via "Bug reports for GNU Emacs,
>>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>>
>> I use proced with 'proced-auto-update-flag' set to 't'. Often I quit the
>> window showing proced buffer and later some profile shows that the timer
>> used to update proced is taking a big chunk of time.
>>
>> Since updating the proced buffer is a somewhat expensive operation, I
>> think the update should happen only if a proced buffer is visible.
>>
>> I can send a patch to that changes 'proced-auto-update-timer' to this
>> effect.
>
> As a user option, this sounds useful.  So please do send a patch, but
> please add such an option, because I can imagine users who'd like
> Proced buffers to be always up-to-date, regardless of whether they are
> displayed.
>
> Thanks.

What about a special value 'visible' for proced-auto-update-flag instead
of a separate option?

The only wrinkle might be how to set this value using
proced-toggle-auto-update. There is also the slight inconsistency that
it makes proced-auto-update-flag not a flag.

Rahguzar