fix: retry portal when it fails, and only apply theme changes when there is a relevant change

src/app/cosmic.rs

@@ -156,6 +156,7 @@ where
         }
     }
 
+    #[allow(clippy::too_many_lines)]
     fn subscription(&self) -> Subscription<Self::Message> {
         let window_events = listen_with(|event, _| {
             match event {
@@ -429,6 +430,11 @@ impl<T: Application> Cosmic<T> {
             }
 
             Message::SystemThemeChange(keys, theme) => {
+                let cur_is_dark = THEME.with(|t| t.borrow().theme_type.is_dark());
+                // Ignore updates if the current theme mode does not match.
+                if cur_is_dark != theme.cosmic().is_dark {
+                    return iced::Command::none();
+                }
                 let cmd = self.app.system_theme_update(&keys, theme.cosmic());
                 // Record the last-known system theme in event that the current theme is custom.
                 self.app.core_mut().system_theme = theme.clone();
@@ -472,6 +478,9 @@ impl<T: Application> Cosmic<T> {
                 };
             }
             Message::SystemThemeModeChange(keys, mode) => {
+                if !keys.contains(&"is_dark") {
+                    return iced::Command::none();
+                }
                 if THEME.with(|t| match t.borrow().theme_type {
                     ThemeType::System {
                         theme: _,

src/theme/portal.rs

@@ -1,7 +1,6 @@
 use ashpd::desktop::settings::{ColorScheme, Contrast};
 use ashpd::desktop::Color;
 use iced::futures::{self, select, FutureExt, SinkExt, StreamExt};
-use iced::Subscription;
 use iced_futures::subscription;
 use tracing::error;
 
@@ -15,11 +14,20 @@ pub enum Desktop {
 pub fn desktop_settings() -> iced_futures::Subscription<Desktop> {
     subscription::channel(std::any::TypeId::of::<Desktop>(), 10, |mut tx| {
         async move {
+            let mut attempts = 0;
+            loop {
                 let Ok(settings) = ashpd::desktop::settings::Settings::new().await else {
-                // wait forever
                     error!("Failed to create the settings proxy");
-                futures::future::pending::<()>().await;
+                    #[cfg(feature = "tokio")]
-                unreachable!()
+                    ::tokio::time::sleep(::tokio::time::Duration::from_secs(2_u64.pow(attempts)))
+                        .await;
+                    #[cfg(not(feature = "tokio"))]
+                    {
+                        pending::<()>().await;
+                        unreachable!();
+                    }
+                    attempts += 1;
+                    continue;
                 };
 
                 match settings.color_scheme().await {
@@ -46,6 +54,9 @@ pub fn desktop_settings() -> iced_futures::Subscription<Desktop> {
                 }
 
                 loop {
+                    if color_scheme_stream.is_none() && contrast_stream.is_none() {
+                        break;
+                    }
                     let next_color_scheme = async {
                         if let Some(s) = color_scheme_stream.as_mut() {
                             return s.next().await;
@@ -77,6 +88,9 @@ pub fn desktop_settings() -> iced_futures::Subscription<Desktop> {
                             }
                         }
                     };
+                    // Reset the attempts counter if we successfully received a change
+                    attempts = 0;
+                }
             }
         }
     })