Poll cef from separate thread

Author: adamgerhant

desktop/src/app.rs

@@ -4,14 +4,12 @@ use crate::WindowSize;
 use crate::render::GraphicsState;
 use std::sync::Arc;
 use std::sync::mpsc::Sender;
-use std::time::Duration;
+use std::thread::JoinHandle;
 use std::time::Instant;
 use winit::application::ApplicationHandler;
 use winit::dpi::PhysicalSize;
-use winit::event::StartCause;
 use winit::event::WindowEvent;
 use winit::event_loop::ActiveEventLoop;
-use winit::event_loop::ControlFlow;
 use winit::event_loop::EventLoopProxy;
 use winit::window::Window;
 use winit::window::WindowId;
@@ -27,10 +25,11 @@ pub(crate) struct WinitApp {
 	_viewport_frame_buffer: Option<FrameBuffer>,
 	graphics_state: Option<GraphicsState>,
 	event_loop_proxy: EventLoopProxy<CustomEvent>,
+	handle: Option<JoinHandle<()>>,
 }
 
 impl WinitApp {
-	pub(crate) fn new(cef_context: cef::Context<cef::Initialized>, window_size_sender: Sender<WindowSize>, event_loop_proxy: EventLoopProxy<CustomEvent>) -> Self {
+	pub(crate) fn new(cef_context: cef::Context<cef::Initialized>, window_size_sender: Sender<WindowSize>, event_loop_proxy: EventLoopProxy<CustomEvent>, handle: JoinHandle<()>) -> Self {
 		Self {
 			cef_context,
 			window: None,
@@ -40,27 +39,12 @@ impl WinitApp {
 			graphics_state: None,
 			window_size_sender,
 			event_loop_proxy,
+			handle: Some(handle),
 		}
 	}
 }
 
 impl ApplicationHandler<CustomEvent> for WinitApp {
-	fn about_to_wait(&mut self, event_loop: &ActiveEventLoop) {
-		// Set a timeout in case we miss any cef schedule requests
-		let timeout = Instant::now() + Duration::from_millis(100);
-		let wait_until = timeout.min(self.cef_schedule.unwrap_or(timeout));
-		event_loop.set_control_flow(ControlFlow::WaitUntil(wait_until));
-	}
-
-	fn new_events(&mut self, _event_loop: &ActiveEventLoop, _cause: StartCause) {
-		if let Some(schedule) = self.cef_schedule
-			&& schedule < Instant::now()
-		{
-			self.cef_schedule = None;
-			self.cef_context.work();
-		}
-	}
-
 	fn resumed(&mut self, event_loop: &ActiveEventLoop) {
 		let window = Arc::new(
 			event_loop
@@ -90,15 +74,16 @@ impl ApplicationHandler<CustomEvent> for WinitApp {
 					window.request_redraw();
 				}
 			}
-			CustomEvent::ScheduleBrowserWork(instant) => {
-				if let Some(graphics_state) = self.graphics_state.as_mut()
-					&& let Some(frame_buffer) = &self.ui_frame_buffer
-					&& graphics_state.ui_texture_outdated(frame_buffer)
-				{
-					self.cef_context.work();
-					let _ = self.event_loop_proxy.send_event(CustomEvent::ScheduleBrowserWork(Instant::now() + Duration::from_millis(1)));
-				}
-				self.cef_schedule = Some(instant);
+			CustomEvent::WorkCef => {
+				self.cef_context.work();
+			}
+			CustomEvent::KeepProcessAliveWhenResizing(window_size) => {
+				let Some(frame_buffer) = &self.ui_frame_buffer else {
+					return;
+				};
+				if window_size.width != frame_buffer.width() || window_size.height != frame_buffer.height() {
+					let _ = self.event_loop_proxy.send_event(CustomEvent::KeepProcessAliveWhenResizing(window_size));
+				};
 			}
 		}
 	}
@@ -112,17 +97,15 @@ impl ApplicationHandler<CustomEvent> for WinitApp {
 				event_loop.exit();
 			}
 			WindowEvent::Resized(PhysicalSize { width, height }) => {
-				let _ = self.window_size_sender.send(WindowSize::new(width as usize, height as usize));
-				if let Some(ref mut graphics_state) = self.graphics_state {
-					graphics_state.resize(width, height);
-				}
+				let window_size = WindowSize::new(width as usize, height as usize);
+				let _ = self.window_size_sender.send(window_size);
 				self.cef_context.notify_of_resize();
+				self.event_loop_proxy.send_event(CustomEvent::KeepProcessAliveWhenResizing(window_size));
 			}
 
 			WindowEvent::RedrawRequested => {
 				let Some(ref mut graphics_state) = self.graphics_state else { return };
 				// Only rerender once we have a new ui texture to display
-
 				match graphics_state.render() {
 					Ok(_) => {}
 					Err(wgpu::SurfaceError::Lost) => {
@@ -136,8 +119,9 @@ impl ApplicationHandler<CustomEvent> for WinitApp {
 			}
 			_ => {}
 		}
+	}
 
-		// Notify cef of possible input events
-		self.cef_context.work();
+	fn exiting(&mut self, _event_loop: &ActiveEventLoop) {
+		let _ = self.handle.take().unwrap().join();
 	}
 }

desktop/src/cef.rs

@@ -1,6 +1,9 @@
 use crate::{CustomEvent, FrameBuffer};
 use std::{
-	sync::{Arc, Mutex, mpsc::Receiver},
+	sync::{
+		Arc, Mutex,
+		mpsc::{Receiver, Sender},
+	},
 	time::Instant,
 };
 
@@ -21,7 +24,7 @@ pub(crate) trait CefEventHandler: Clone {
 	fn schedule_cef_message_loop_work(&self, scheduled_time: Instant);
 }
 
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
 pub(crate) struct WindowSize {
 	pub(crate) width: usize,
 	pub(crate) height: usize,
@@ -33,11 +36,6 @@ impl WindowSize {
 	}
 }
 
-#[derive(Clone)]
-pub(crate) struct CefHandler {
-	window_size_receiver: Arc<Mutex<WindowSizeReceiver>>,
-	event_loop_proxy: EventLoopProxy<CustomEvent>,
-}
 struct WindowSizeReceiver {
 	receiver: Receiver<WindowSize>,
 	window_size: WindowSize,
@@ -50,11 +48,20 @@ impl WindowSizeReceiver {
 		}
 	}
 }
+
+#[derive(Clone)]
+pub(crate) struct CefHandler {
+	window_size_receiver: Arc<Mutex<WindowSizeReceiver>>,
+	event_loop_proxy: EventLoopProxy<CustomEvent>,
+	poll_cef_sender: Sender<Instant>,
+}
+
 impl CefHandler {
-	pub(crate) fn new(window_size_receiver: Receiver<WindowSize>, event_loop_proxy: EventLoopProxy<CustomEvent>) -> Self {
+	pub(crate) fn new(window_size_receiver: Receiver<WindowSize>, event_loop_proxy: EventLoopProxy<CustomEvent>, poll_cef_sender: Sender<Instant>) -> Self {
 		Self {
 			window_size_receiver: Arc::new(Mutex::new(WindowSizeReceiver::new(window_size_receiver))),
 			event_loop_proxy,
+			poll_cef_sender,
 		}
 	}
 }
@@ -71,11 +78,12 @@ impl CefEventHandler for CefHandler {
 		}
 		*window_size
 	}
+
 	fn draw(&self, frame_buffer: FrameBuffer) {
 		let _ = self.event_loop_proxy.send_event(CustomEvent::UiUpdate(frame_buffer));
 	}
 
 	fn schedule_cef_message_loop_work(&self, scheduled_time: std::time::Instant) {
-		let _ = self.event_loop_proxy.send_event(CustomEvent::ScheduleBrowserWork(scheduled_time));
+		let _ = self.poll_cef_sender.send(scheduled_time);
 	}
 }

desktop/src/main.rs

@@ -1,6 +1,6 @@
-use std::fmt::Debug;
 use std::process::exit;
-use std::time::Instant;
+use std::time::{Duration, Instant};
+use std::{fmt::Debug, thread};
 
 use tracing_subscriber::EnvFilter;
 use winit::event_loop::EventLoop;
@@ -19,7 +19,8 @@ mod dirs;
 #[derive(Debug)]
 pub(crate) enum CustomEvent {
 	UiUpdate(FrameBuffer),
-	ScheduleBrowserWork(Instant),
+	WorkCef,
+	KeepProcessAliveWhenResizing(WindowSize),
 }
 
 fn main() {
@@ -35,10 +36,12 @@ fn main() {
 	};
 
 	let event_loop = EventLoop::<CustomEvent>::with_user_event().build().unwrap();
+	let event_loop_proxy = event_loop.create_proxy();
 
 	let (window_size_sender, window_size_receiver) = std::sync::mpsc::channel();
+	let (poll_cef_sender, poll_cef_receiver) = std::sync::mpsc::channel();
 
-	let cef_context = match cef_context.init(cef::CefHandler::new(window_size_receiver, event_loop.create_proxy())) {
+	let cef_context = match cef_context.init(cef::CefHandler::new(window_size_receiver, event_loop_proxy.clone(), poll_cef_sender)) {
 		Ok(c) => c,
 		Err(cef::InitError::InitializationFailed) => {
 			tracing::error!("Cef initialization failed");
@@ -47,8 +50,24 @@ fn main() {
 	};
 
 	tracing::info!("Cef initialized successfully");
+	let poll_cef_elp = event_loop_proxy.clone();
+	let handle = thread::spawn(move || {
+		loop {
+			match poll_cef_receiver.recv_timeout(Duration::from_millis(100)) {
+				Ok(scheduled_instant) => {
+					if scheduled_instant > Instant::now() {
+						thread::sleep(scheduled_instant - Instant::now());
+					}
+					let _ = poll_cef_elp.send_event(CustomEvent::WorkCef);
+				}
+				Err(_) => {
+					let _ = poll_cef_elp.send_event(CustomEvent::WorkCef);
+				}
+			}
+		}
+	});
 
-	let mut winit_app = WinitApp::new(cef_context, window_size_sender, event_loop.create_proxy());
+	let mut winit_app = WinitApp::new(cef_context, window_size_sender, event_loop_proxy.clone(), handle);
 
 	event_loop.run_app(&mut winit_app).unwrap();
 }

desktop/src/render.rs

@@ -223,13 +223,7 @@ impl GraphicsState {
 		graphics_state
 	}
 
-	pub(crate) fn ui_texture_outdated(&self, frame_buffer: &FrameBuffer) -> bool {
-		let width = frame_buffer.width() as u32;
-		let height = frame_buffer.height() as u32;
-
-		self.config.width != width || self.config.height != height
-	}
-	pub(crate) fn resize(&mut self, width: u32, height: u32) {
+	pub(crate) fn try_resize(&mut self, width: u32, height: u32) {
 		if width > 0 && height > 0 && (self.config.width != width || self.config.height != height) {
 			self.config.width = width;
 			self.config.height = height;
@@ -248,7 +242,26 @@ impl GraphicsState {
 				usage: wgpu::TextureUsages::TEXTURE_BINDING | wgpu::TextureUsages::COPY_DST,
 				view_formats: &[],
 			});
+
+			let texture_view = texture.create_view(&wgpu::TextureViewDescriptor::default());
 			self.texture = Some(texture);
+
+			let bind_group = self.device.create_bind_group(&wgpu::BindGroupDescriptor {
+				layout: &self.render_pipeline.get_bind_group_layout(0),
+				entries: &[
+					wgpu::BindGroupEntry {
+						binding: 0,
+						resource: wgpu::BindingResource::TextureView(&texture_view),
+					},
+					wgpu::BindGroupEntry {
+						binding: 1,
+						resource: wgpu::BindingResource::Sampler(&self.sampler),
+					},
+				],
+				label: Some("texture_bind_group"),
+			});
+
+			self.bind_group = Some(bind_group);
 		}
 	}
 
@@ -257,7 +270,7 @@ impl GraphicsState {
 		let width = frame_buffer.width() as u32;
 		let height = frame_buffer.height() as u32;
 
-		self.resize(width, height);
+		self.try_resize(width, height);
 
 		let Some(ref texture) = self.texture else { return };
 
@@ -280,25 +293,6 @@ impl GraphicsState {
 				depth_or_array_layers: 1,
 			},
 		);
-
-		let texture_view = texture.create_view(&wgpu::TextureViewDescriptor::default());
-
-		let bind_group = self.device.create_bind_group(&wgpu::BindGroupDescriptor {
-			layout: &self.render_pipeline.get_bind_group_layout(0),
-			entries: &[
-				wgpu::BindGroupEntry {
-					binding: 0,
-					resource: wgpu::BindingResource::TextureView(&texture_view),
-				},
-				wgpu::BindGroupEntry {
-					binding: 1,
-					resource: wgpu::BindingResource::Sampler(&self.sampler),
-				},
-			],
-			label: Some("texture_bind_group"),
-		});
-
-		self.bind_group = Some(bind_group);
 	}
 
 	pub(crate) fn render(&mut self) -> Result<(), wgpu::SurfaceError> {