Desktop: Use the OS temp directory for CEF caches (#4030)

* Desktop: Use the OS temp dir

* Review

desktop/src/cef/context/builder.rs

@@ -4,15 +4,15 @@ use cef::{
 	App, BrowserSettings, CefString, Client, DictionaryValue, ImplCommandLine, ImplRequestContext, LogSeverity, RequestContextSettings, SchemeHandlerFactory, Settings, WindowInfo, api_hash,
 	browser_host_create_browser_sync, execute_process,
 };
-use std::path::{Path, PathBuf};
+use std::path::Path;
 
 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, delete_instance_dirs};
 use crate::cef::input::InputState;
 use crate::cef::internal::{BrowserProcessAppImpl, BrowserProcessClientImpl, RenderProcessAppImpl, SchemeHandlerFactoryImpl};
+use crate::dirs::TempDir;
 
 pub(crate) struct CefContextBuilder<H: CefEventHandler> {
 	pub(crate) args: Args,
@@ -97,8 +97,7 @@ 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 instance_dir = TempDir::new().expect("Failed to create temporary directory for CEF instance");
 
 		let exe = std::env::current_exe().expect("cannot get current exe path");
 		let app_root = exe.parent().and_then(|p| p.parent()).expect("bad path structure").parent().expect("bad path structure");
@@ -108,7 +107,7 @@ impl<H: CefEventHandler> CefContextBuilder<H> {
 			multi_threaded_message_loop: 0,
 			external_message_pump: 1,
 			no_sandbox: 1, // GPU helper crashes when running with sandbox
-			..Self::common_settings(&instance_dir)
+			..Self::common_settings(instance_dir.as_ref())
 		};
 
 		self.initialize_inner(&event_handler, settings)?;
@@ -118,14 +117,13 @@ 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 instance_dir = TempDir::new().expect("Failed to create temporary directory for CEF instance");
 
 		let settings = Settings {
 			multi_threaded_message_loop: 1,
 			#[cfg(target_os = "linux")]
 			no_sandbox: 1,
-			..Self::common_settings(&instance_dir)
+			..Self::common_settings(instance_dir.as_ref())
 		};
 
 		self.initialize_inner(&event_handler, settings)?;
@@ -157,7 +155,7 @@ impl<H: CefEventHandler> CefContextBuilder<H> {
 	}
 }
 
-fn create_browser<H: CefEventHandler>(event_handler: H, instance_dir: PathBuf, disable_gpu_acceleration: bool) -> Result<SingleThreadedCefContext, InitError> {
+fn create_browser<H: CefEventHandler>(event_handler: H, instance_dir: TempDir, disable_gpu_acceleration: bool) -> Result<SingleThreadedCefContext, InitError> {
 	let mut client = Client::new(BrowserProcessClientImpl::new(&event_handler));
 
 	#[cfg(feature = "accelerated_paint")]
@@ -211,7 +209,7 @@ fn create_browser<H: CefEventHandler>(event_handler: H, instance_dir: PathBuf, d
 			event_handler: Box::new(event_handler),
 			browser,
 			input_state: InputState::default(),
-			instance_dir,
+			_instance_dir: instance_dir,
 		})
 	} else {
 		tracing::error!("Failed to create browser");

desktop/src/cef/context/multithreaded.rs

@@ -54,7 +54,12 @@ impl CefContext for MultiThreadedCefContextProxy {
 impl Drop for MultiThreadedCefContextProxy {
 	fn drop(&mut self) {
 		// Force dropping underlying context on the UI thread
-		run_on_ui_thread(move || drop(CONTEXT.take()));
+		let (sync_drop_tx, sync_drop_rx) = std::sync::mpsc::channel();
+		run_on_ui_thread(move || {
+			drop(CONTEXT.take());
+			let _ = sync_drop_tx.send(());
+		});
+		let _ = sync_drop_rx.recv();
 	}
 }
 

desktop/src/cef/context/singlethreaded.rs

@@ -4,6 +4,7 @@ use winit::event::WindowEvent;
 use crate::cef::input::InputState;
 use crate::cef::ipc::{MessageType, SendMessage};
 use crate::cef::{CefEventHandler, input};
+use crate::dirs::TempDir;
 
 use super::CefContext;
 
@@ -11,7 +12,7 @@ pub(super) struct SingleThreadedCefContext {
 	pub(super) event_handler: Box<dyn CefEventHandler>,
 	pub(super) browser: Browser,
 	pub(super) input_state: InputState,
-	pub(super) instance_dir: std::path::PathBuf,
+	pub(super) _instance_dir: TempDir,
 }
 
 impl CefContext for SingleThreadedCefContext {
@@ -46,19 +47,6 @@ impl Drop for SingleThreadedCefContext {
 		// 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.
-		// 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));
-				}
-			}
-		}
 	}
 }
 
@@ -68,7 +56,6 @@ impl SendMessage for SingleThreadedCefContext {
 			tracing::error!("Main frame is not available, cannot send message");
 			return;
 		};
-
 		frame.send_message(message_type, message);
 	}
 }

desktop/src/cef/dirs.rs

@@ -1,24 +0,0 @@
-use std::path::PathBuf;
-
-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 = app_data_dir().join(CEF_DIR_NAME).join(instance_id);
-	ensure_dir_exists(&path);
-	path
-}