fix(wm): restart bm and wsr notif handlers on fail

This commit ensures that if and when either the border_manager or
workspace_reconciliator notification handlers crash in their respective
threads, they will be restarted instead of killing the whole thread.

This is acheived via a loop running in the spawned threads of both
listeners, which will report whichever error killed the notification
handler functions.

Clippy annotations to deny expect and unwrap calls have been added to
these two modules.

Calls to DestroyWindow for expired borders were sporadically failing in
unpredictable circumstances, so these have been switched out with calls
to CloseWindow which has been working well so far with the stackbar
feature.

justfile

@@ -28,6 +28,7 @@ install:
     just install-target komorebi
 
 run:
+    just install-target komorebic
     cargo +stable run --bin komorebi --locked
 
 warn $RUST_LOG="warn":
@@ -43,6 +44,7 @@ trace $RUST_LOG="trace":
     just run
 
 deadlock $RUST_LOG="trace":
+    just install-komorebic
     cargo +stable run --bin komorebi --locked --features deadlock_detection
 
 docgen:

komorebi/src/border_manager/mod.rs

@@ -18,11 +18,8 @@ use std::sync::atomic::AtomicI32;
 use std::sync::atomic::AtomicU32;
 use std::sync::Arc;
 use std::sync::OnceLock;
-use std::time::Duration;
-use std::time::Instant;
 use windows::Win32::Foundation::HWND;
 
-use crate::workspace_reconciliator::ALT_TAB_HWND;
 use crate::Colour;
 use crate::Rect;
 use crate::Rgb;
@@ -124,37 +121,23 @@ pub fn handle_notifications(wm: Arc<Mutex<WindowManager>>) -> color_eyre::Result
     tracing::info!("listening");
 
     let receiver = event_rx();
-    let mut instant: Option<Instant> = None;
-    event_tx().send(Notification)?;
 
     'receiver: for _ in receiver {
-        if let Some(instant) = instant {
-            if instant.elapsed().lt(&Duration::from_millis(50)) {
-                continue 'receiver;
-            }
-        }
-
-        instant = Some(Instant::now());
-
         let mut borders = BORDER_STATE.lock();
         let mut borders_monitors = BORDERS_MONITORS.lock();
 
         // Check the wm state every time we receive a notification
         let state = wm.lock();
 
-        // If borders are disabled
-        if !BORDER_ENABLED.load_consume()
-           // Or if the wm is paused
-            || state.is_paused
-            // Or if we are handling an alt-tab across workspaces
-            || ALT_TAB_HWND.load().is_some()
-        {
-            // Destroy the borders we know about
-            for (_, border) in borders.iter() {
-                border.destroy()?;
+        if !BORDER_ENABLED.load_consume() || state.is_paused {
+            if !borders.is_empty() {
+                for (_, border) in borders.iter() {
+                    border.destroy()?;
+                }
+
+                borders.clear();
             }
 
-            borders.clear();
             continue 'receiver;
         }
 

komorebi/src/process_event.rs

@@ -1,8 +1,6 @@
 use std::fs::OpenOptions;
 use std::sync::atomic::Ordering;
 use std::sync::Arc;
-use std::time::Duration;
-use std::time::Instant;
 
 use color_eyre::eyre::anyhow;
 use color_eyre::Result;
@@ -25,8 +23,6 @@ use crate::window_manager_event::WindowManagerEvent;
 use crate::windows_api::WindowsApi;
 use crate::winevent::WinEvent;
 use crate::workspace_reconciliator;
-use crate::workspace_reconciliator::ALT_TAB_HWND;
-use crate::workspace_reconciliator::ALT_TAB_HWND_INSTANT;
 use crate::Notification;
 use crate::NotificationEvent;
 use crate::DATA_DIR;
@@ -275,24 +271,6 @@ impl WindowManager {
                 for (i, monitors) in self.monitors().iter().enumerate() {
                     for (j, workspace) in monitors.workspaces().iter().enumerate() {
                         if workspace.contains_window(window.hwnd) && focused_pair != (i, j) {
-                            // At this point we know we are going to send a notification to the workspace reconciliator
-                            // So we get the topmost window returned by EnumWindows, which is almost always the window
-                            // that has been selected by alt-tab
-                            if let Ok(alt_tab_windows) = WindowsApi::alt_tab_windows() {
-                                if let Some(first) =
-                                    alt_tab_windows.iter().find(|w| w.title().is_ok())
-                                {
-                                    // If our record of this HWND hasn't been updated in over a minute
-                                    let mut instant = ALT_TAB_HWND_INSTANT.lock();
-                                    if instant.elapsed().gt(&Duration::from_secs(1)) {
-                                        // Update our record with the HWND we just found
-                                        ALT_TAB_HWND.store(Some(first.hwnd));
-                                        // Update the timestamp of our record
-                                        *instant = Instant::now();
-                                    }
-                                }
-                            }
-
                             workspace_reconciliator::event_tx().send(
                                 workspace_reconciliator::Notification {
                                     monitor_idx: i,

komorebi/src/windows_api.rs

@@ -139,7 +139,6 @@ use crate::monitor::Monitor;
 use crate::ring::Ring;
 use crate::set_window_position::SetWindowPosition;
 use crate::windows_callbacks;
-use crate::Window;
 
 pub enum WindowsResult<T, E> {
     Err(E),
@@ -494,16 +493,6 @@ impl WindowsApi {
         unsafe { GetWindow(hwnd, GW_HWNDNEXT) }.process()
     }
 
-    pub fn alt_tab_windows() -> Result<Vec<Window>> {
-        let mut hwnds = vec![];
-        Self::enum_windows(
-            Some(windows_callbacks::alt_tab_windows),
-            &mut hwnds as *mut Vec<Window> as isize,
-        )?;
-
-        Ok(hwnds)
-    }
-
     #[allow(dead_code)]
     pub fn top_visible_window() -> Result<isize> {
         let hwnd = Self::top_window()?;

komorebi/src/windows_callbacks.rs

@@ -152,26 +152,6 @@ pub extern "system" fn enum_window(hwnd: HWND, lparam: LPARAM) -> BOOL {
     true.into()
 }
 
-pub extern "system" fn alt_tab_windows(hwnd: HWND, lparam: LPARAM) -> BOOL {
-    let windows = unsafe { &mut *(lparam.0 as *mut Vec<Window>) };
-
-    let is_visible = WindowsApi::is_window_visible(hwnd);
-    let is_window = WindowsApi::is_window(hwnd);
-    let is_minimized = WindowsApi::is_iconic(hwnd);
-
-    if is_visible && is_window && !is_minimized {
-        let window = Window { hwnd: hwnd.0 };
-
-        if let Ok(should_manage) = window.should_manage(None, &mut RuleDebug::default()) {
-            if should_manage {
-                windows.push(window);
-            }
-        }
-    }
-
-    true.into()
-}
-
 pub extern "system" fn win_event_hook(
     _h_win_event_hook: HWINEVENTHOOK,
     event: u32,

komorebi/src/workspace_reconciliator.rs

@@ -1,16 +1,11 @@
 #![deny(clippy::unwrap_used, clippy::expect_used)]
 
-use crate::border_manager;
 use crate::WindowManager;
 use crossbeam_channel::Receiver;
 use crossbeam_channel::Sender;
-use crossbeam_utils::atomic::AtomicCell;
-use lazy_static::lazy_static;
 use parking_lot::Mutex;
 use std::sync::Arc;
 use std::sync::OnceLock;
-use std::time::Duration;
-use std::time::Instant;
 
 #[derive(Copy, Clone)]
 pub struct Notification {
@@ -18,12 +13,6 @@ pub struct Notification {
     pub workspace_idx: usize,
 }
 
-pub static ALT_TAB_HWND: AtomicCell<Option<isize>> = AtomicCell::new(None);
-
-lazy_static! {
-    pub static ref ALT_TAB_HWND_INSTANT: Arc<Mutex<Instant>> = Arc::new(Mutex::new(Instant::now()));
-}
-
 static CHANNEL: OnceLock<(Sender<Notification>, Receiver<Notification>)> = OnceLock::new();
 
 pub fn channel() -> &'static (Sender<Notification>, Receiver<Notification>) {
@@ -45,11 +34,7 @@ pub fn listen_for_notifications(wm: Arc<Mutex<WindowManager>>) {
                 tracing::warn!("restarting finished thread");
             }
             Err(error) => {
-                if cfg!(debug_assertions) {
-                    tracing::error!("restarting failed thread: {:?}", error)
-                } else {
-                    tracing::error!("restarting failed thread: {}", error)
-                }
+                tracing::warn!("restarting failed thread: {}", error);
             }
         }
     });
@@ -58,11 +43,9 @@ pub fn handle_notifications(wm: Arc<Mutex<WindowManager>>) -> color_eyre::Result
     tracing::info!("listening");
 
     let receiver = event_rx();
-    let arc = wm.clone();
 
     for notification in receiver {
         tracing::info!("running reconciliation");
-
         let mut wm = wm.lock();
         let focused_monitor_idx = wm.focused_monitor_idx();
         let focused_workspace_idx =
@@ -79,36 +62,6 @@ pub fn handle_notifications(wm: Arc<Mutex<WindowManager>>) -> color_eyre::Result
                 monitor.focus_workspace(notification.workspace_idx)?;
                 monitor.load_focused_workspace(mouse_follows_focus)?;
             }
-
-            // Drop our lock on the window manager state here to not slow down updates
-            drop(wm);
-
-            // Check if there was an alt-tab across workspaces in the last second
-            if let Some(hwnd) = ALT_TAB_HWND.load() {
-                if ALT_TAB_HWND_INSTANT
-                    .lock()
-                    .elapsed()
-                    .lt(&Duration::from_secs(1))
-                {
-                    // Sleep for 100 millis to let other events pass
-                    std::thread::sleep(Duration::from_millis(100));
-                    tracing::info!("focusing alt-tabbed window");
-
-                    // Take a new lock on the wm and try to focus the container with
-                    // the recorded HWND from the alt-tab
-                    let mut wm = arc.lock();
-                    if let Ok(workspace) = wm.focused_workspace_mut() {
-                        // Regardless of if this fails, we need to get past this part
-                        // to unblock the border manager below
-                        let _ = workspace.focus_container_by_window(hwnd);
-                    }
-
-                    // Unblock the border manager
-                    ALT_TAB_HWND.store(None);
-                    // Send a notification to the border manager to update the borders
-                    border_manager::event_tx().send(border_manager::Notification)?;
-                }
-            }
         }
     }