fix busyloop while waiting for WlBuffers to be released

We changed from SlotPool to Multipool, which let us fix the busyloop.

daemon/src/animations/mod.rs

@@ -140,14 +140,17 @@ impl Animator {
                             continue;
                         }
 
-                        if !wallpapers[i].canvas_change(|canvas| frame.unpack(canvas)) {
-                            error!("failed to unpack frame, canvas has the wrong size");
+                        let (success, buffer) =
+                            wallpapers[i].canvas_change(|canvas| frame.unpack(canvas));
+
+                        if !success {
+                            error!("failed to unpack frame, canvas is smaller than expected");
                             wallpapers.swap_remove(i);
                             tokens.swap_remove(i);
                             continue;
                         }
 
-                        wallpapers[i].draw();
+                        wallpapers[i].draw(&buffer);
                         i += 1;
                     }
 

daemon/src/animations/transitions.rs

@@ -137,12 +137,12 @@ impl Transition {
         while !done {
             done = true;
             for wallpaper in self.wallpapers.iter_mut() {
-                wallpaper.canvas_change(|canvas| {
+                let (_, buffer) = wallpaper.canvas_change(|canvas| {
                     for (old, new) in canvas.chunks_exact_mut(4).zip(new_img.chunks_exact(3)) {
                         change_cols!(step, old, new, done);
                     }
                 });
-                wallpaper.draw();
+                wallpaper.draw(&buffer);
             }
             self.send_frame(&mut now);
         }
@@ -155,7 +155,7 @@ impl Transition {
         let mut now = Instant::now();
         while start.elapsed().as_secs_f64() < seq.duration() {
             for wallpaper in self.wallpapers.iter_mut() {
-                wallpaper.canvas_change(|canvas| {
+                let (_, buffer) = wallpaper.canvas_change(|canvas| {
                     canvas
                         .par_chunks_exact_mut(4)
                         .zip(new_img.par_chunks_exact(3))
@@ -166,7 +166,7 @@ impl Transition {
                             }
                         });
                 });
-                wallpaper.draw();
+                wallpaper.draw(&buffer);
             }
             self.send_frame(&mut now);
             step = seq.now() as f64;
@@ -224,7 +224,7 @@ impl Transition {
 
         while start.elapsed().as_secs_f64() < seq.duration() {
             for wallpaper in self.wallpapers.iter_mut() {
-                wallpaper.canvas_change(|canvas| {
+                let (_, buffer) = wallpaper.canvas_change(|canvas| {
                     canvas
                         .par_chunks_exact_mut(4)
                         .zip(new_img.par_chunks_exact(3))
@@ -237,7 +237,7 @@ impl Transition {
                             }
                         });
                 });
-                wallpaper.draw();
+                wallpaper.draw(&buffer);
             }
             self.send_frame(&mut now);
 
@@ -285,7 +285,7 @@ impl Transition {
 
         while start.elapsed().as_secs_f64() < seq.duration() {
             for wallpaper in self.wallpapers.iter_mut() {
-                wallpaper.canvas_change(|canvas| {
+                let (_, buffer) = wallpaper.canvas_change(|canvas| {
                     canvas
                         .par_chunks_exact_mut(4)
                         .zip(new_img.par_chunks_exact(3))
@@ -298,7 +298,7 @@ impl Transition {
                             }
                         });
                 });
-                wallpaper.draw();
+                wallpaper.draw(&buffer);
             }
             self.send_frame(&mut now);
 
@@ -332,7 +332,7 @@ impl Transition {
         let mut now = Instant::now();
         while start.elapsed().as_secs_f64() < seq.duration() {
             for wallpaper in self.wallpapers.iter_mut() {
-                wallpaper.canvas_change(|canvas| {
+                let (_, buffer) = wallpaper.canvas_change(|canvas| {
                     canvas
                         .par_chunks_exact_mut(4)
                         .zip(new_img.par_chunks_exact(3))
@@ -351,7 +351,7 @@ impl Transition {
                             }
                         });
                 });
-                wallpaper.draw();
+                wallpaper.draw(&buffer);
             }
             self.send_frame(&mut now);
 
@@ -383,7 +383,7 @@ impl Transition {
         let mut now = Instant::now();
         while start.elapsed().as_secs_f64() < seq.duration() {
             for wallpaper in self.wallpapers.iter_mut() {
-                wallpaper.canvas_change(|canvas| {
+                let (_, buffer) = wallpaper.canvas_change(|canvas| {
                     canvas
                         .par_chunks_exact_mut(4)
                         .zip(new_img.par_chunks_exact(3))
@@ -402,7 +402,7 @@ impl Transition {
                             }
                         });
                 });
-                wallpaper.draw();
+                wallpaper.draw(&buffer);
             }
             self.send_frame(&mut now);
 

daemon/src/main.rs

@@ -36,7 +36,7 @@ use smithay_client_toolkit::{
         wlr_layer::{Layer, LayerShell, LayerShellHandler, LayerSurface, LayerSurfaceConfigure},
         WaylandSurface,
     },
-    shm::{slot::SlotPool, Shm, ShmHandler},
+    shm::{multi::MultiPool, Shm, ShmHandler},
 };
 
 use wayland_client::{
@@ -233,7 +233,7 @@ struct Daemon {
     registry_state: RegistryState,
     output_state: OutputState,
     shm: Shm,
-    pool: Arc<Mutex<SlotPool>>,
+    pool: wallpaper::MtShmPool,
 
     // swww stuff
     wallpapers: Vec<Arc<Wallpaper>>,
@@ -251,7 +251,7 @@ impl Daemon {
         let layer_shell = LayerShell::bind(globals, qh).expect("layer shell is not available");
 
         let shm = Shm::bind(globals, qh).expect("wl_shm is not available");
-        let pool = SlotPool::new(256 * 256 * 4, &shm).expect("failed to create SlotPool");
+        let pool = MultiPool::new(&shm).expect("failed to create MultiPool");
 
         Self {
             // Outputs may be hotplugged at runtime, therefore we need to setup a registry state to
@@ -300,8 +300,8 @@ impl Daemon {
                         }
                         for wallpaper in wallpapers {
                             wallpaper.set_img_info(utils::ipc::BgImg::Color(color));
-                            wallpaper.clear(color);
-                            wallpaper.draw();
+                            let buffer = wallpaper.clear(color);
+                            wallpaper.draw(&buffer);
                         }
                         wake_poll();
                     }) {
@@ -409,7 +409,7 @@ impl CompositorHandler for Daemon {
     ) {
         for wallpaper in self.wallpapers.iter_mut() {
             if wallpaper.has_surface(surface) {
-                wallpaper.draw();
+                wallpaper.draw(&wallpaper.canvas_change(|_| {}).1);
                 return;
             }
         }

daemon/src/wallpaper.rs

@@ -14,10 +14,15 @@ use smithay_client_toolkit::{
         wlr_layer::{Anchor, KeyboardInteractivity, LayerSurface},
         WaylandSurface,
     },
-    shm::slot::{Slot, SlotPool},
+    shm,
 };
 
-use wayland_client::protocol::{wl_shm, wl_surface::WlSurface};
+use wayland_client::protocol::{wl_buffer::WlBuffer, wl_shm, wl_surface::WlSurface};
+
+/// The memory pool wallpapers use
+pub type ShmPool = shm::multi::MultiPool<(WlSurface, u32)>;
+/// The memory pool, multithreaded
+pub type MtShmPool = Arc<Mutex<ShmPool>>;
 
 #[derive(Debug)]
 struct AnimationState {
@@ -44,12 +49,12 @@ impl Drop for AnimationToken {
 }
 
 /// Owns all the necessary information for drawing.
+#[derive(Debug)]
 struct WallpaperInner {
     width: NonZeroI32,
     height: NonZeroI32,
     scale_factor: NonZeroI32,
 
-    slot: Slot,
     img: BgImg,
 }
 
@@ -59,16 +64,12 @@ pub struct Wallpaper {
     layer_surface: LayerSurface,
 
     animation_state: AnimationState,
-    pool: Arc<Mutex<SlotPool>>,
+    pool: MtShmPool,
     pub configured: AtomicBool,
 }
 
 impl Wallpaper {
-    pub fn new(
-        output_info: OutputInfo,
-        layer_surface: LayerSurface,
-        pool: Arc<Mutex<SlotPool>>,
-    ) -> Self {
+    pub fn new(output_info: OutputInfo, layer_surface: LayerSurface, pool: MtShmPool) -> Self {
         let (width, height): (NonZeroI32, NonZeroI32) = if let Some(size) = output_info.logical_size
         {
             if size.0 == 0 || size.1 == 0 {
@@ -81,17 +82,6 @@ impl Wallpaper {
         };
 
         let scale_factor = NonZeroI32::new(output_info.scale_factor).unwrap();
-        let slot = pool
-            .lock()
-            .unwrap()
-            .new_slot(
-                width.get() as usize
-                    * height.get() as usize
-                    * scale_factor.get() as usize
-                    * scale_factor.get() as usize
-                    * 4,
-            )
-            .expect("failed to create slot in pool");
 
         // Configure the layer surface
         layer_surface.set_anchor(Anchor::all());
@@ -113,7 +103,6 @@ impl Wallpaper {
                 width,
                 height,
                 scale_factor,
-                slot,
                 img: BgImg::Color([0, 0, 0]),
             }),
             animation_state: AnimationState {
@@ -151,13 +140,13 @@ impl Wallpaper {
     }
 
     #[inline]
-    fn lock(&self) -> (RwLockReadGuard<WallpaperInner>, MutexGuard<SlotPool>) {
-        (self.inner.read().unwrap(), self.pool.lock().unwrap())
+    fn lock(&self) -> (RwLockReadGuard<WallpaperInner>, MutexGuard<ShmPool>) {
+        (self.lock_inner(), self.pool.lock().unwrap())
     }
 
     #[inline]
-    fn lock_mut(&self) -> (RwLockWriteGuard<WallpaperInner>, MutexGuard<SlotPool>) {
-        (self.inner.write().unwrap(), self.pool.lock().unwrap())
+    fn lock_mut(&self) -> (RwLockWriteGuard<WallpaperInner>, MutexGuard<ShmPool>) {
+        (self.lock_inner_mut(), self.pool.lock().unwrap())
     }
 
     #[inline]
@@ -170,23 +159,33 @@ impl Wallpaper {
         self.inner.write().unwrap()
     }
 
-    pub fn canvas_change<F, T>(&self, f: F) -> T
+    pub fn canvas_change<F, T>(&self, f: F) -> (T, WlBuffer)
     where
         F: FnOnce(&mut [u8]) -> T,
     {
-        let mut nano_sleep = 2000000; // start at 2 ms, half it every loop
+        let (inner, mut pool) = self.lock();
+        let width = inner.width.get() * inner.scale_factor.get();
+        let stride = width * 4;
+        let height = inner.height.get() * inner.scale_factor.get();
+        drop(inner);
+        let mut frame = 0u32;
         loop {
-            {
-                let (inner, mut pool) = self.lock();
-                if let Some(canvas) = inner.slot.canvas(&mut pool) {
-                    log::debug!("got canvas! - output {}", self.output_id);
-                    return f(canvas);
-                }
+            match pool.create_buffer(
+                width,
+                stride,
+                height,
+                &(self.layer_surface.wl_surface().clone(), frame),
+                wl_shm::Format::Xrgb8888,
+            ) {
+                Ok((_offset, buffer, canvas)) => return (f(canvas), buffer.clone()),
+                Err(e) => match e {
+                    smithay_client_toolkit::shm::multi::PoolError::InUse => frame += 1,
+                    smithay_client_toolkit::shm::multi::PoolError::Overlap => {
+                        pool.remove(&(self.layer_surface.wl_surface().clone(), frame));
+                    }
+                    smithay_client_toolkit::shm::multi::PoolError::NotFound => unreachable!(),
+                },
             }
-            log::debug!("failed to get canvas - output {}", self.output_id);
-            // sleep to mitigate busy waiting
-            std::thread::sleep(std::time::Duration::from_nanos(nano_sleep));
-            nano_sleep /= 2;
         }
     }
 
@@ -213,34 +212,30 @@ impl Wallpaper {
             .store(false, Ordering::Release);
     }
 
-    pub fn clear(&self, color: [u8; 3]) {
+    pub fn clear(&self, color: [u8; 3]) -> WlBuffer {
         self.canvas_change(|canvas| {
             for pixel in canvas.chunks_exact_mut(4) {
                 pixel[2] = color[0];
                 pixel[1] = color[1];
                 pixel[0] = color[2];
             }
-        });
+        })
+        .1
     }
 
     pub fn set_img_info(&self, img_info: BgImg) {
         log::debug!("output {} - drawing: {}", self.output_id, img_info);
         self.lock_inner_mut().img = img_info;
     }
 
-    pub fn draw(&self) {
-        let (inner, mut pool) = self.lock();
-
+    pub fn draw(&self, buf: &WlBuffer) {
+        let inner = self.lock_inner();
         let width = inner.width.get() * inner.scale_factor.get();
         let height = inner.height.get() * inner.scale_factor.get();
-        let stride = width * 4;
-
-        let buf = pool
-            .create_buffer_in(&inner.slot, width, height, stride, wl_shm::Format::Xrgb8888)
-            .unwrap();
         drop(inner);
+
         let surface = self.layer_surface.wl_surface();
-        buf.attach_to(surface).unwrap();
+        surface.attach(Some(buf), 0, 0);
         surface.damage_buffer(0, 0, width, height);
         surface.commit();
     }
@@ -262,21 +257,25 @@ impl Wallpaper {
             return;
         }
         self.inc_animation_id();
+
+        // remove all buffers with the previous size
+        let mut frame = 0u32;
+        while pool
+            .remove(&(self.layer_surface.wl_surface().clone(), frame))
+            .is_some()
+        {
+            frame += 1;
+        }
+        drop(pool);
+
         inner.width = width;
         inner.height = height;
         inner.scale_factor = scale_factor;
-        inner.slot = pool
-            .new_slot(
-                inner.width.get() as usize
-                    * inner.height.get() as usize
-                    * inner.scale_factor.get() as usize
-                    * inner.scale_factor.get() as usize
-                    * 4,
-            )
-            .expect("failed to create slot");
+
         self.layer_surface
             .set_size(inner.width.get() as u32, inner.height.get() as u32);
         inner.img = BgImg::Color([0, 0, 0]);
+        drop(inner);
         self.layer_surface.commit();
         self.configured.store(false, Ordering::Release);
     }

utils/src/ipc.rs

@@ -101,7 +101,7 @@ impl ArchivedPosition {
     }
 }
 
-#[derive(PartialEq, Clone, Archive, Serialize, Deserialize)]
+#[derive(Debug, PartialEq, Clone, Archive, Serialize, Deserialize)]
 #[archive_attr(derive(PartialEq))]
 pub enum BgImg {
     Color([u8; 3]),