present_sync: rewrite around linked list

When this was originally written, the queuing/list approach was
deliberately removed since it adds more complication and xorg/wayland
don't really use it anyway. In practice, you only really have one frame
in flight with presentation timestamps. However, one slight annoyance is
that the drm code has its own thing which is almost exactly the same and
does its own calculations. Ideally, we'd port drm to this instead, but
the implementation there takes into account N-frames in flight which
probably does actually work. So we need to make present_sync smarter and
be able to handle this.

mpv does actually have its own linked list implementation already which
is a good fit for this. mp_present becomes the list and each
mp_present_entry has its own set of timestamps. During initialization,
we create all the entries we need and then simply treat it like a queue
during the lifecycle of the VO. When an entry is fully used
(present_sync_get_info), then we remove it from the list, zero it out,
and append it to the end for future use. This avoids needing to allocate
memory on every frame (which is what drm currently does) and allows for
a reasonable number of in flight frames at the same time as this should
never grow to some obscene number. The nice thing is that current users
of present_sync don't need to change anything besides the initialization
step.

1 files changed, 3 insertions, 3 deletions

diff --git a/video/out/wayland_common.c b/video/out/wayland_common.c
index 144ff78284..e0f8cde208 100644
--- a/video/out/wayland_common.c
+++ b/video/out/wayland_common.c
@@ -2282,7 +2282,7 @@ bool vo_wayland_init(struct vo *vo)
         wl->fback_pool->len = 8; // max swapchain depth allowed
         wl->fback_pool->fback = talloc_zero_array(wl->fback_pool, struct wp_presentation_feedback *,
                                                   wl->fback_pool->len);
-        wl->present = talloc_zero(wl, struct mp_present);
+        wl->present = mp_present_initialize(wl, 8); // max swapchain depth allowed
     } else {
         MP_VERBOSE(wl, "Compositor doesn't support the %s protocol!\n",
                    wp_presentation_interface.name);
@@ -2560,8 +2560,8 @@ void vo_wayland_wait_frame(struct vo_wayland_state *wl)
      * 3. refresh rate of the output reported by the compositor
      * 4. make up crap if vblank_time is still <= 0 (better than nothing) */
 
-    if (wl->use_present)
-        vblank_time = wl->present->vsync_duration;
+    if (wl->use_present && wl->present->head)
+        vblank_time = wl->present->head->vsync_duration;
 
     if (vblank_time <= 0 && wl->refresh_interval > 0)
         vblank_time = wl->refresh_interval;