screencopy: Wait for SyncPoint before submitting

src/niri.rs

@@ -31,6 +31,7 @@ use smithay::backend::renderer::element::{
     PrimaryScanoutOutput, RenderElementStates,
 };
 use smithay::backend::renderer::gles::GlesRenderer;
+use smithay::backend::renderer::sync::SyncPoint;
 use smithay::backend::renderer::Unbind;
 use smithay::desktop::utils::{
     bbox_from_surface_tree, output_update, send_dmabuf_feedback_surface_tree,
@@ -3771,7 +3772,7 @@ impl Niri {
                         screencopy,
                     );
                     match render_result {
-                        Ok(damages) => {
+                        Ok((sync, damages)) => {
                             if let Some(damages) = damages {
                                 // Convert from Physical coordinates back to Buffer coordinates.
                                 let transform = output.current_transform();
@@ -3786,7 +3787,7 @@ impl Niri {
                                 });
 
                                 screencopy.damage(damages);
-                                queue.pop().submit(false);
+                                queue.pop().submit_after_sync(false, sync, &self.event_loop);
                             } else {
                                 trace!("no damage found, waiting till next redraw");
                             }
@@ -3840,19 +3841,20 @@ impl Niri {
             false,
             damage_tracker,
             &screencopy,
-        )
-        .map(|_damage| ());
+        );
 
-        match render_result {
-            Ok(()) => screencopy.submit(false),
-            Err(_) => {
-                // Recreate damage tracker to report full damage next check.
-                *damage_tracker = OutputDamageTracker::new((0, 0), 1.0, Transform::Normal);
-            }
+        let res = render_result
+            .map(|(sync, _damage)| screencopy.submit_after_sync(false, sync, &self.event_loop));
+
+        if res.is_err() {
+            // Recreate damage tracker to report full damage next check.
+            *damage_tracker = OutputDamageTracker::new((0, 0), 1.0, Transform::Normal);
         }
-        render_result
+
+        res
     }
 
+    #[allow(clippy::type_complexity)]
     fn render_for_screencopy_internal<'a>(
         renderer: &mut GlesRenderer,
         output: &Output,
@@ -3860,7 +3862,7 @@ impl Niri {
         with_damage: bool,
         damage_tracker: &'a mut OutputDamageTracker,
         screencopy: &Screencopy,
-    ) -> anyhow::Result<Option<&'a Vec<Rectangle<i32, Physical>>>> {
+    ) -> anyhow::Result<(Option<SyncPoint>, Option<&'a Vec<Rectangle<i32, Physical>>>)> {
         let OutputModeSource::Static {
             size: last_size,
             scale: last_scale,
@@ -3893,26 +3895,30 @@ impl Niri {
         // Just checked damage tracker has static mode
         let damages = damage_tracker.damage_output(1, &elements).unwrap().0;
         if with_damage && damages.is_none() {
-            return Ok(None);
+            return Ok((None, None));
         }
 
         let elements = elements.iter().rev();
 
-        match screencopy.buffer() {
+        let sync = match screencopy.buffer() {
             ScreencopyBuffer::Dmabuf(dmabuf) => {
-                let _sync =
+                let sync =
                     render_to_dmabuf(renderer, dmabuf.clone(), size, scale, transform, elements)
                         .context("error rendering to screencopy dmabuf")?;
+                Some(sync)
             }
             ScreencopyBuffer::Shm(wl_buffer) => {
                 render_to_shm(renderer, wl_buffer, size, scale, transform, elements)
                     .context("error rendering to screencopy shm buffer")?;
+                None
             }
-        }
+        };
+
         if let Err(err) = renderer.unbind() {
             warn!("error unbinding after rendering for screencopy: {err:?}");
         }
-        Ok(damages)
+
+        Ok((sync, damages))
     }
 
     #[cfg(feature = "xdp-gnome-screencast")]

src/protocols/screencopy.rs

@@ -1,10 +1,14 @@
 use std::collections::HashMap;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
+use std::time::Duration;
 
+use calloop::generic::Generic;
+use calloop::{Interest, LoopHandle, Mode, PostAction};
 use smithay::backend::allocator::dmabuf::Dmabuf;
 use smithay::backend::allocator::{Buffer, Fourcc};
 use smithay::backend::renderer::damage::OutputDamageTracker;
+use smithay::backend::renderer::sync::SyncPoint;
 use smithay::output::Output;
 use smithay::reexports::wayland_protocols_wlr::screencopy::v1::server::zwlr_screencopy_frame_v1::{
     Flags, ZwlrScreencopyFrameV1,
@@ -464,7 +468,7 @@ impl Screencopy {
     }
 
     /// Submit the copied content.
-    pub fn submit(mut self, y_invert: bool) {
+    fn submit(mut self, y_invert: bool, timestamp: Duration) {
         // Notify client that buffer is ordinary.
         self.frame.flags(if y_invert {
             Flags::YInvert
@@ -473,13 +477,34 @@ impl Screencopy {
         });
 
         // Notify client about successful copy.
-        let time = get_monotonic_time();
-        let tv_sec_hi = (time.as_secs() >> 32) as u32;
-        let tv_sec_lo = (time.as_secs() & 0xFFFFFFFF) as u32;
-        let tv_nsec = time.subsec_nanos();
+        let tv_sec_hi = (timestamp.as_secs() >> 32) as u32;
+        let tv_sec_lo = (timestamp.as_secs() & 0xFFFFFFFF) as u32;
+        let tv_nsec = timestamp.subsec_nanos();
         self.frame.ready(tv_sec_hi, tv_sec_lo, tv_nsec);
 
         // Mark frame as submitted to ensure destructor isn't run.
         self.submitted = true;
     }
+
+    pub fn submit_after_sync<T>(
+        self,
+        y_invert: bool,
+        sync_point: Option<SyncPoint>,
+        event_loop: &LoopHandle<'_, T>,
+    ) {
+        let timestamp = get_monotonic_time();
+        match sync_point.and_then(|s| s.export()) {
+            None => self.submit(y_invert, timestamp),
+            Some(sync_fd) => {
+                let source = Generic::new(sync_fd, Interest::READ, Mode::OneShot);
+                let mut screencopy = Some(self);
+                event_loop
+                    .insert_source(source, move |_, _, _| {
+                        screencopy.take().unwrap().submit(y_invert, timestamp);
+                        Ok(PostAction::Remove)
+                    })
+                    .unwrap();
+            }
+        }
+    }
 }