Desktop: Make shutdown more robust and fix panic caused by invalid viewport scale (#3783)

* Fix panic caused by invalid viewport scale

* Make shutdown more robust

desktop/src/app.rs

@@ -1,6 +1,8 @@
 use rand::Rng;
 use rfd::AsyncFileDialog;
 use std::fs;
+use std::sync::Arc;
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::mpsc::{Receiver, Sender, SyncSender};
 use std::thread;
 use std::time::{Duration, Instant};
@@ -45,6 +47,7 @@ pub(crate) struct App {
 	persistent_data: PersistentData,
 	cli: Cli,
 	startup_time: Option<Instant>,
+	exiting: Arc<AtomicBool>,
 	exit_reason: ExitReason,
 }
 
@@ -68,14 +71,20 @@ impl App {
 		})
 		.expect("Error setting Ctrl-C handler");
 
+		let exiting = Arc::new(AtomicBool::new(false));
+
 		let rendering_app_event_scheduler = app_event_scheduler.clone();
 		let (start_render_sender, start_render_receiver) = std::sync::mpsc::sync_channel(1);
+		let exiting_clone = exiting.clone();
 		std::thread::spawn(move || {
 			let runtime = tokio::runtime::Runtime::new().unwrap();
 			loop {
 				let result = runtime.block_on(DesktopWrapper::execute_node_graph());
 				rendering_app_event_scheduler.schedule(AppEvent::NodeGraphExecutionResult(result));
 				let _ = start_render_receiver.recv_timeout(Duration::from_millis(10));
+				if exiting_clone.load(Ordering::Relaxed) {
+					break;
+				}
 			}
 		});
 
@@ -107,8 +116,9 @@ impl App {
 			web_communication_startup_buffer: Vec::new(),
 			persistent_data,
 			cli,
-			exit_reason: ExitReason::Shutdown,
 			startup_time: None,
+			exiting,
+			exit_reason: ExitReason::Shutdown,
 		}
 	}
 
@@ -118,6 +128,10 @@ impl App {
 	}
 
 	fn exit(&mut self, reason: Option<ExitReason>) {
+		if self.exiting.swap(true, Ordering::Relaxed) {
+			return;
+		}
+		let _ = self.start_render_sender.send(());
 		if let Some(reason) = reason {
 			self.exit_reason = reason;
 		}

desktop/src/cef/context/multithreaded.rs

@@ -53,7 +53,8 @@ impl CefContext for MultiThreadedCefContextProxy {
 
 impl Drop for MultiThreadedCefContextProxy {
 	fn drop(&mut self) {
-		cef::shutdown();
+		// Force dropping underlying context on the UI thread
+		run_on_ui_thread(move || drop(CONTEXT.take()));
 	}
 }
 

desktop/src/cef/context/singlethreaded.rs

@@ -42,6 +42,10 @@ impl CefContext for SingleThreadedCefContext {
 
 impl Drop for SingleThreadedCefContext {
 	fn drop(&mut self) {
+		tracing::debug!("Shutting down CEF");
+
+		// CEF wants us to close the browser before shutting down, otherwise it may run longer that necessary.
+		self.browser.host().unwrap().close_browser(1);
 		cef::shutdown();
 
 		// Sometimes some CEF processes still linger at this point and hold file handles to the cache directory.