Desktop: Limit application to a single instance (#3441)

* only allow single instance

* more reliable CEF cache cleanup

* some cleanup

* fix lock file location

* add simple signal handling

* fix skew handles on desktop

* mac remove unused helpers

desktop/src/cef/context/builder.rs

@@ -11,7 +11,7 @@ use super::CefContext;
 use super::singlethreaded::SingleThreadedCefContext;
 use crate::cef::CefEventHandler;
 use crate::cef::consts::{RESOURCE_DOMAIN, RESOURCE_SCHEME};
-use crate::cef::dirs::create_instance_dir;
+use crate::cef::dirs::{create_instance_dir, delete_instance_dirs};
 use crate::cef::input::InputState;
 use crate::cef::internal::{BrowserProcessAppImpl, BrowserProcessClientImpl, RenderProcessAppImpl, SchemeHandlerFactoryImpl};
 
@@ -85,6 +85,7 @@ impl<H: CefEventHandler> CefContextBuilder<H> {
 
 	#[cfg(target_os = "macos")]
 	pub(crate) fn initialize(self, event_handler: H, disable_gpu_acceleration: bool) -> Result<impl CefContext, InitError> {
+		delete_instance_dirs();
 		let instance_dir = create_instance_dir();
 
 		let exe = std::env::current_exe().expect("cannot get current exe path");
@@ -105,6 +106,7 @@ impl<H: CefEventHandler> CefContextBuilder<H> {
 
 	#[cfg(not(target_os = "macos"))]
 	pub(crate) fn initialize(self, event_handler: H, disable_gpu_acceleration: bool) -> Result<impl CefContext, InitError> {
+		delete_instance_dirs();
 		let instance_dir = create_instance_dir();
 
 		let settings = Settings {

desktop/src/cef/context/singlethreaded.rs

@@ -43,7 +43,19 @@ impl CefContext for SingleThreadedCefContext {
 impl Drop for SingleThreadedCefContext {
 	fn drop(&mut self) {
 		cef::shutdown();
-		std::fs::remove_dir_all(&self.instance_dir).expect("Failed to remove CEF cache directory");
+
+		// Sometimes some CEF processes still linger at this point and hold file handles to the cache directory.
+		// To mitigate this, we try to remove the directory multiple times with some delay.
+		// TODO: find a better solution if possible.
+		for _ in 0..30 {
+			match std::fs::remove_dir_all(&self.instance_dir) {
+				Ok(_) => break,
+				Err(e) => {
+					tracing::warn!("Failed to remove CEF cache directory, retrying...: {e}");
+					std::thread::sleep(std::time::Duration::from_millis(100));
+				}
+			}
+		}
 	}
 }
 

desktop/src/cef/dirs.rs

@@ -1,12 +1,24 @@
 use std::path::PathBuf;
 
-use crate::dirs::{ensure_dir_exists, graphite_data_dir};
+use crate::dirs::{app_data_dir, ensure_dir_exists};
 
 static CEF_DIR_NAME: &str = "browser";
 
+pub(crate) fn delete_instance_dirs() {
+	let cef_dir = app_data_dir().join(CEF_DIR_NAME);
+	if let Ok(entries) = std::fs::read_dir(&cef_dir) {
+		for entry in entries.flatten() {
+			let path = entry.path();
+			if path.is_dir() {
+				let _ = std::fs::remove_dir_all(&path);
+			}
+		}
+	}
+}
+
 pub(crate) fn create_instance_dir() -> PathBuf {
 	let instance_id: String = (0..32).map(|_| format!("{:x}", rand::random::<u8>() % 16)).collect();
-	let path = graphite_data_dir().join(CEF_DIR_NAME).join(instance_id);
+	let path = app_data_dir().join(CEF_DIR_NAME).join(instance_id);
 	ensure_dir_exists(&path);
 	path
 }

desktop/src/cef/input.rs

@@ -1,4 +1,4 @@
-use cef::sys::{cef_event_flags_t, cef_key_event_type_t, cef_mouse_button_type_t};
+use cef::sys::{cef_key_event_type_t, cef_mouse_button_type_t};
 use cef::{Browser, ImplBrowser, ImplBrowserHost, KeyEvent, MouseEvent};
 use winit::event::{ButtonSource, ElementState, MouseButton, MouseScrollDelta, WindowEvent};
 
@@ -6,7 +6,7 @@ mod keymap;
 use keymap::{ToCharRepresentation, ToNativeKeycode, ToVKBits};
 
 mod state;
-pub(crate) use state::InputState;
+pub(crate) use state::{CefModifiers, InputState};
 
 use super::consts::{PINCH_ZOOM_SPEED, SCROLL_LINE_HEIGHT, SCROLL_LINE_WIDTH, SCROLL_SPEED_X, SCROLL_SPEED_Y};
 
@@ -129,9 +129,10 @@ pub(crate) fn handle_window_event(browser: &Browser, input_state: &mut InputStat
 			}
 			let Some(host) = browser.host() else { return };
 
-			let mut mouse_event: MouseEvent = input_state.into();
-			mouse_event.modifiers |= cef_event_flags_t::EVENTFLAG_CONTROL_DOWN.0 as u32;
-			mouse_event.modifiers |= cef_event_flags_t::EVENTFLAG_PRECISION_SCROLLING_DELTA.0 as u32;
+			let mouse_event = MouseEvent {
+				modifiers: CefModifiers::PINCH_MODIFIERS.into(),
+				..input_state.into()
+			};
 
 			let delta = (delta * PINCH_ZOOM_SPEED).round() as i32;
 

desktop/src/cef/input/state.rs

@@ -240,10 +240,17 @@ impl CefModifiers {
 
 		Self(inner)
 	}
+
+	pub(super) const PINCH_MODIFIERS: Self = Self(cef_event_flags_t(
+		cef_event_flags_t::EVENTFLAG_CONTROL_DOWN.0 | cef_event_flags_t::EVENTFLAG_PRECISION_SCROLLING_DELTA.0,
+	));
 }
 
-impl Into<u32> for CefModifiers {
-	fn into(self) -> u32 {
-		self.0.0 as u32
+impl From<CefModifiers> for u32 {
+	fn from(val: CefModifiers) -> Self {
+		#[cfg(not(target_os = "windows"))]
+		return val.0.0;
+		#[cfg(target_os = "windows")]
+		return val.0.0 as u32;
 	}
 }