From fe86356399138973f6d85e900f729e4709343310 Mon Sep 17 00:00:00 2001
From: NotAShelf <raf@notashelf.dev>
Date: Fri, 27 Mar 2026 08:39:49 +0300
Subject: [PATCH] wayland: use arc-swap over Mutex for `FOCUSED_APP` for better
 concurrency

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Id6b40d5c533c35dda5bce7b852b836f26a6a6964
---
 Cargo.lock         | 10 ++++++++++
 Cargo.toml         |  3 ++-
 src/wayland/mod.rs | 19 +++++++++----------
 3 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index fe1039d..8ea168d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -88,6 +88,15 @@ version = "1.0.102"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
 
+[[package]]
+name = "arc-swap"
+version = "1.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a07d1f37ff60921c83bdfc7407723bdefe89b44b98a9b772f225c8f9d67141a6"
+dependencies = [
+ "rustversion",
+]
+
 [[package]]
 name = "async-broadcast"
 version = "0.7.2"
@@ -2409,6 +2418,7 @@ checksum = "6ce2be8dc25455e1f91df71bfa12ad37d7af1092ae736f3a6cd0e37bc7810596"
 name = "stash-clipboard"
 version = "0.3.6"
 dependencies = [
+ "arc-swap",
  "base64",
  "blocking",
  "clap",
diff --git a/Cargo.toml b/Cargo.toml
index bfc3800..bae39c5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,6 +14,7 @@ name = "stash"       # actual binary name for Nix, Cargo, etc.
 path = "src/main.rs"
 
 [dependencies]
+arc-swap              = { version = "1.9.0", optional = true }
 base64                = "0.22.1"
 blocking              = "1.6.2"
 clap                  = { version = "4.6.0", features = [ "derive", "env" ] }
@@ -50,7 +51,7 @@ tempfile = "3.27.0"
 [features]
 default       = [ "notifications", "use-toplevel" ]
 notifications = [ "dep:notify-rust" ]
-use-toplevel  = [ "dep:wayland-client", "dep:wayland-protocols-wlr" ]
+use-toplevel  = [ "dep:arc-swap", "dep:wayland-client", "dep:wayland-protocols-wlr" ]
 
 [profile.release]
 lto       = true
diff --git a/src/wayland/mod.rs b/src/wayland/mod.rs
index 9cfa765..38f6ff5 100644
--- a/src/wayland/mod.rs
+++ b/src/wayland/mod.rs
@@ -1,8 +1,9 @@
 use std::{
   collections::HashMap,
-  sync::{LazyLock, Mutex},
+  sync::{Arc, LazyLock, Mutex},
 };
 
+use arc_swap::ArcSwapOption;
 use log::debug;
 use wayland_client::{
   Connection as WaylandConnection,
@@ -17,7 +18,7 @@ use wayland_protocols_wlr::foreign_toplevel::v1::client::{
   zwlr_foreign_toplevel_manager_v1::{self, ZwlrForeignToplevelManagerV1},
 };
 
-static FOCUSED_APP: Mutex<Option<String>> = Mutex::new(None);
+static FOCUSED_APP: ArcSwapOption<String> = ArcSwapOption::const_empty();
 static TOPLEVEL_APPS: LazyLock<Mutex<HashMap<ObjectId, String>>> =
   LazyLock::new(|| Mutex::new(HashMap::new()));
 
@@ -32,12 +33,11 @@ pub fn init_wayland_state() {
 
 /// Get the currently focused window application name using Wayland protocols
 pub fn get_focused_window_app() -> Option<String> {
-  // Try Wayland protocol first
-  if let Ok(focused) = FOCUSED_APP.lock()
-    && let Some(ref app) = *focused
-  {
+  // Load the focused app using lock-free arc-swap
+  let focused = FOCUSED_APP.load();
+  if let Some(app) = focused.as_ref() {
     debug!("Found focused app via Wayland protocol: {app}");
-    return Some(app.clone());
+    return Some(app.to_string());
   }
 
   debug!("No focused window detection method worked");
@@ -152,12 +152,11 @@ impl Dispatch<ZwlrForeignToplevelHandleV1, ()> for AppState {
         }) {
           debug!("Toplevel activated");
           // Update focused app to the `app_id` of this handle
-          if let (Ok(apps), Ok(mut focused)) =
-            (TOPLEVEL_APPS.lock(), FOCUSED_APP.lock())
+          if let Ok(apps) = TOPLEVEL_APPS.lock()
             && let Some(app_id) = apps.get(&handle_id)
           {
             debug!("Setting focused app to: {app_id}");
-            *focused = Some(app_id.clone());
+            FOCUSED_APP.store(Some(Arc::new(app_id.clone())));
           }
         }
       },