per carousel semaphore

src/ui/album_carousel/album.rs

@@ -2,7 +2,8 @@ use crate::model;
 use adw::gdk;
 use adw::{prelude::*, subclass::prelude::*};
 use glib::subclass::InitializingObject;
-use std::cell::{Cell, RefCell};
+use std::cell::{Cell, OnceCell, RefCell};
+use std::rc::Rc;
 use tokio::sync::Semaphore;
 use tracing::{event, Level};
 
@@ -20,6 +21,8 @@ mod imp {
         cover_art: RefCell<Option<gdk::Paintable>>,
 
         pub cover_art_loading: Cell<Option<glib::JoinHandle<()>>>,
+
+        pub semaphore: OnceCell<Rc<Semaphore>>,
     }
 
     #[glib::object_subclass]
@@ -45,9 +48,6 @@ mod imp {
     impl BinImpl for Album {}
 }
 
-// only fetch 10 thumbnails at a time
-static SEM: Semaphore = Semaphore::const_new(10);
-
 glib::wrapper! {
     pub struct Album(ObjectSubclass<imp::Album>)
         @extends adw::Bin, gtk::Widget,
@@ -55,6 +55,13 @@ glib::wrapper! {
 }
 
 impl Album {
+    fn semaphore(&self) -> &Rc<Semaphore> {
+        // only load 5 at a time
+        self.imp()
+            .semaphore
+            .get_or_init(|| Rc::new(Semaphore::new(5)))
+    }
+
     pub fn bind(&self, client: &crate::wrappers::Client, album: &model::Album) {
         self.set_item(Some(album));
 
@@ -62,8 +69,9 @@ impl Album {
         let id = album.id();
         let this = self.downgrade();
         let scale_factor = self.scale_factor() as u32;
+        let sem = Rc::clone(self.semaphore());
         let handle = glib::spawn_future_local(async move {
-            let _permit = SEM.acquire().await.unwrap();
+            let _permit = sem.acquire().await.unwrap();
 
             // see pixel-size in album_carousel_album.blp
             let pixbuf = match client.cover_art(&id, Some(160 * scale_factor)).await {