event loop and timers

[Carlo Wood]

You might want to consider using my tool set, that was
written for high performance applications. It features
a thread pool with a fixed number of pre-started threads
and will never create a new thread. You can run millions
of timers at the same time without any noticeable overhead.

See https://carlowood.github.io/statefultask/ for some
preliminary documentation.

It also comes with xcb support (https://github.com/CarloWood/xcb-task)
which can be used to hand off the X socket of xcb to the
I/O event loop thread of statefultask (it has a single thread
that does all calls to epoll for any fd events).


On Sun, 01 Sep 2024 09:30:22 -0400
Steven J Abner <pheonix.sja at att.net> wrote:

>   Having an issue with using timers with 'beginner loop'. From
> scratch, created a window that handles events, with display port
> rectangles within the window. So basically one window with one main
> context or draw surface, and multiple 'dp rectangles' within. When
> resizing a window, these 'dp rectangles' adjust their size or
> 'configure'. A 'dp rectangle' can also have a grip for resizing. This
> can be better visualized as the window's context being a desktop
> background, and the 'dp rectangle' as a window being resized on said
> desktop. When dragging the grip, the resizing can stutter or jump
> positions in a less than smooth fashion. The solution is a timer to
> fire off XCB_EXPOSE after an accumulation of invalid bounding areas
> rather than XCB_EXPOSE on every XCB_MOTION_NOTIFY.
>  Using a timer with sigev_notify = SIGEV_THREAD works perfectly in
> this situation, but spams the heck out of creating a thread, and
> makes debugging almost useless because of reporting the million
> thread creations.
>  Using a timer with sigev_signo = SIGALRM, or SIGUSR1 only partially 
> works until crash caused xcb_send_request_with_fds64 locks, or
> forever wait.
>  My question then becomes: can I parse 'event->response_type' > 0x7F
> to intercept signals or will this algorithm be a possible untested 
> solution:
> 
> while (run_loop) {
>   while ( !has_timers && (event = xcb_wait_for_event(connection)) ) {
> parse_event:
>   }
>   while (has_timers) {
>       /* run timers until event, run event return, until no timers */
>     _timer_update()
>     if ((event = xcb_poll_for_event(connection)) != NULL)
>       goto parse_event;
>   }
> }
> 
> static void
> _timer_update() {
> 
>   clock_gettime(CLOCK_MONOTONIC, &ts);
>   if (elapsed) {
>     call handler(); // may delete timer
>     if (id)  update next firing
>     else if (--timer_count == 0) has_timers = false;
>   }
> }
> 
>   Any insight would be greatly appreciated!
> Steve
> 
>