desktop: Add GameModeSession for managing gamemode

desktop/src/dbus.rs

@@ -1,6 +1,9 @@
 #![cfg(target_os = "linux")]
 //! Types and methods utilized for communicating with D-Bus
 
+use std::mem;
+use std::sync::{Arc, Mutex};
+
 use futures::StreamExt;
 use zbus::export::futures_core::Stream;
 use zbus::zvariant::{OwnedValue, Value};
@@ -80,3 +83,56 @@ impl<'p> FreedesktopSettings<'p> {
         }
     }
 }
+
+pub struct GameModeSession {
+    _guard: Arc<Mutex<Option<GameModeGuard>>>,
+}
+
+impl GameModeSession {
+    pub fn new(enabled: bool) -> Self {
+        let guard = Arc::new(Mutex::new(None));
+        let guard2 = guard.clone();
+        tokio::spawn(async move {
+            let game_mode_guard = GameModeGuard::new(enabled).await;
+            *guard2.lock().expect("Non-poisoned gamemode guard") = Some(game_mode_guard);
+        });
+        Self { _guard: guard }
+    }
+}
+
+struct GameModeGuard {
+    gamemode: Option<ashpd::desktop::game_mode::GameMode<'static>>,
+}
+
+impl GameModeGuard {
+    async fn new(enabled: bool) -> Self {
+        if !enabled {
+            return Self { gamemode: None };
+        }
+
+        let gamemode = ashpd::desktop::game_mode::GameMode::new()
+            .await
+            .inspect_err(|err| tracing::warn!("Failed to initialize gamemode controller: {}", err))
+            .ok();
+
+        if let Some(gamemode) = &gamemode {
+            if let Err(err) = gamemode.register(std::process::id()).await {
+                tracing::warn!("Failed to register a game with gamemode: {}", err)
+            }
+        }
+
+        Self { gamemode }
+    }
+}
+
+impl Drop for GameModeGuard {
+    fn drop(&mut self) {
+        if let Some(gamemode) = mem::take(&mut self.gamemode) {
+            tokio::spawn(async move {
+                if let Err(err) = gamemode.unregister(std::process::id()).await {
+                    tracing::warn!("Failed to unregister a game with gamemode: {}", err)
+                }
+            });
+        }
+    }
+}