Text, many performance improvements

lib/ui_platform_wayland/src/lib.rs

@@ -1,7 +1,10 @@
 use std::error::Error;
 use std::ffi::c_void;
+use std::io::ErrorKind;
 use std::num::NonZeroU32;
+use std::os::fd::{AsFd, AsRawFd};
 use std::ptr::NonNull;
+use std::time::Duration;
 
 use raw_window_handle::{
     DisplayHandle, HandleError, HasDisplayHandle, HasWindowHandle, RawDisplayHandle,
@@ -44,6 +47,12 @@ pub struct FrameRequest {
     pub resized: bool,
 }
 
+#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
+pub struct WaitOutcome {
+    pub dispatched: usize,
+    pub external_ready: bool,
+}
+
 pub struct WaylandWindow {
     event_queue: wayland_client::EventQueue<State>,
     surface_target: WaylandSurfaceTarget,
@@ -139,6 +148,127 @@ impl WaylandWindow {
         Ok(())
     }
 
+    pub fn dispatch_pending(&mut self) -> Result<usize, Box<dyn Error>> {
+        let dispatched = self.event_queue.dispatch_pending(&mut self.state)?;
+        self.event_queue.flush()?;
+        Ok(dispatched)
+    }
+
+    pub fn wait_for_events(&mut self, timeout: Duration) -> Result<usize, Box<dyn Error>> {
+        Ok(self.wait_for_events_or_fd(None, timeout)?.dispatched)
+    }
+
+    pub fn poll_fd(&self) -> i32 {
+        self.state._connection.as_fd().as_raw_fd()
+    }
+
+    pub fn dispatch_ready(&mut self) -> Result<usize, Box<dyn Error>> {
+        self.event_queue.flush()?;
+
+        let dispatched = self.event_queue.dispatch_pending(&mut self.state)?;
+        if dispatched > 0 {
+            return Ok(dispatched);
+        }
+
+        let Some(read_guard) = self.event_queue.prepare_read() else {
+            return Ok(self.event_queue.dispatch_pending(&mut self.state)?);
+        };
+
+        match read_guard.read() {
+            Ok(_) => {}
+            Err(wayland_client::backend::WaylandError::Io(e))
+                if e.kind() == ErrorKind::WouldBlock =>
+            {
+                return Ok(0);
+            }
+            Err(error) => return Err(Box::new(error)),
+        }
+
+        Ok(self.event_queue.dispatch_pending(&mut self.state)?)
+    }
+
+    pub fn wait_for_events_or_fd(
+        &mut self,
+        external_fd: Option<i32>,
+        timeout: Duration,
+    ) -> Result<WaitOutcome, Box<dyn Error>> {
+        self.event_queue.flush()?;
+
+        let dispatched = self.event_queue.dispatch_pending(&mut self.state)?;
+        if dispatched > 0 {
+            return Ok(WaitOutcome {
+                dispatched,
+                external_ready: false,
+            });
+        }
+
+        let Some(read_guard) = self.event_queue.prepare_read() else {
+            return Ok(WaitOutcome {
+                dispatched: self.event_queue.dispatch_pending(&mut self.state)?,
+                external_ready: false,
+            });
+        };
+        let fd = read_guard.connection_fd();
+        let mut pollfds = [
+            libc::pollfd {
+                fd: fd.as_raw_fd(),
+                events: libc::POLLIN | libc::POLLERR,
+                revents: 0,
+            },
+            libc::pollfd {
+                fd: external_fd.unwrap_or(-1),
+                events: libc::POLLIN | libc::POLLERR,
+                revents: 0,
+            },
+        ];
+        let pollfd_count = if external_fd.is_some() { 2 } else { 1 };
+        let timeout_ms = timeout.as_millis().min(i32::MAX as u128) as i32;
+        let ready = loop {
+            let ready = unsafe { libc::poll(pollfds.as_mut_ptr(), pollfd_count, timeout_ms) };
+            if ready >= 0 {
+                break ready;
+            }
+            let error = std::io::Error::last_os_error();
+            if error.kind() == ErrorKind::Interrupted {
+                continue;
+            }
+            return Err(Box::new(error));
+        };
+
+        if ready == 0 {
+            drop(read_guard);
+            return Ok(WaitOutcome::default());
+        }
+        let external_ready =
+            external_fd.is_some() && (pollfds[1].revents & (libc::POLLIN | libc::POLLERR)) != 0;
+        let wayland_ready = (pollfds[0].revents & (libc::POLLIN | libc::POLLERR)) != 0;
+        if !wayland_ready {
+            drop(read_guard);
+            return Ok(WaitOutcome {
+                dispatched: 0,
+                external_ready,
+            });
+        }
+
+        match read_guard.read() {
+            Ok(_) => {}
+            Err(wayland_client::backend::WaylandError::Io(e))
+                if e.kind() == ErrorKind::WouldBlock =>
+            {
+                return Ok(WaitOutcome {
+                    dispatched: 0,
+                    external_ready,
+                });
+            }
+            Err(error) => return Err(Box::new(error)),
+        }
+
+        Ok(WaitOutcome {
+            dispatched: self.event_queue.dispatch_pending(&mut self.state)?,
+            external_ready,
+        })
+    }
+
     pub fn request_redraw(&mut self) {
         self.state.request_redraw();
     }