Re: What, exactly, _is_ "line-breakout optimization"?

[Bill Gray]

Hi Branden,  all,

On 5/19/24 17:06, G. Branden Robinson wrote:
> https://github.com/ThomasDickey/ncurses-snapshots/blob/master/ncurses/tty/tty_update.c#L1018
> https://github.com/ThomasDickey/ncurses-snapshots/blob/master/ncurses/tty/tty_update.c#L367

   Interesting.  Looks as if a check for key input is done every five 
changed lines,  if typeahead() is enabled.

> Too bad those line numbers will desync over time.  cgit makes it easier
> to pin a URL to a tag.  I'm not sure how to do it on GitHub.  (Anyone
> know?)

   Click on the line number of interest (367 or 1018).  "..." appears; 
click on that.  You get the options to 'copy line',  'copy permalink', 
'view git blame',  or 'view file in different branch/tag'.  You want the 
second option,  a permanent link to that line in that branch :

https://github.com/ThomasDickey/ncurses-snapshots/blob/2078627a4637bd5fa6e9a557a48894618b10112d/ncurses/tty/tty_update.c#L367

https://github.com/ThomasDickey/ncurses-snapshots/blob/2078627a4637bd5fa6e9a557a48894618b10112d/ncurses/tty/tty_update.c#L1018

> >   I see PDCurses had this capability,  but it was removed because
> >   "the line-breakout optimization system... simply didn't work,  and
> >   never has"[1].  At this point,  screen refreshes are fast enough
> >   that I don't see how the capability could be useful.
>
> You may be forgetting the poor dogs who use real terminal emulators and
> operate them over network connections.  ;-)  I was in Australia for a
> few years and got a reminder of how obsolete such concerns _aren't_.

   True,  and it might matter for the VT platform in PDCursesMod. 
Other platforms for PDCurses* will all be local.

> But I'll grant, for a local application, typeahead(-1) seems a likely
> win, or at worst harmless.
>
> If PDCurses(-mod) apps get run over latent connections, I expect RDP or
> similar gets used to attack the same problem, so I wouldn't say you made
> the wrong choice for your implementation.

   I can't claim credit (or blame),  since the removal goes back to 
2005/2006,  well before my involvement.  I would imagine that 
typeahead() probably _did_ matter back in the early days of PDCurses or 
its predecessors,  though.

-- Bill

> Regards,
> Branden