feat: use CacheEntry enum to abort previously failed lookups

src/cache.rs

@@ -4,40 +4,56 @@ use std::path::{Path, PathBuf};
 use std::sync::Mutex;
 
 pub(crate) static CACHE: Lazy<Cache> = Lazy::new(Cache::default);
-type IconMap = BTreeMap<(String, u16, u16), PathBuf>;
+type IconMap = BTreeMap<(String, u16, u16), CacheEntry>;
 type ThemeMap = BTreeMap<String, IconMap>;
 
 #[derive(Default)]
 pub(crate) struct Cache(Mutex<ThemeMap>);
 
+#[derive(Debug, Clone, PartialEq)]
+pub enum CacheEntry {
+    // We already looked for this and nothing was found, indicates we should not try to perform a lookup.
+    NotFound,
+    // We have this entry.
+    Found(PathBuf),
+    // We don't know this entry yet, indicate we should perform a lookup.
+    Unknown,
+}
+
 impl Cache {
-    pub fn insert(&self, theme: &str, size: u16, scale: u16, icon_name: &str, icon_path: &Path) {
+    pub fn insert<P: AsRef<Path>>(
+        &self,
+        theme: &str,
+        size: u16,
+        scale: u16,
+        icon_name: &str,
+        icon_path: &Option<P>,
+    ) {
         let mut theme_map = self.0.lock().unwrap();
+        let entry = icon_path
+            .as_ref()
+            .map(|path| CacheEntry::Found(path.as_ref().to_path_buf()))
+            .unwrap_or(CacheEntry::NotFound);
 
         match theme_map.get_mut(theme) {
             Some(icon_map) => {
-                icon_map.insert(
-                    (icon_name.to_string(), size, scale),
-                    icon_path.to_path_buf(),
-                );
+                icon_map.insert((icon_name.to_string(), size, scale), entry);
             }
             None => {
                 let mut icon_map = BTreeMap::new();
-                icon_map.insert(
-                    (icon_name.to_string(), size, scale),
-                    icon_path.to_path_buf(),
-                );
+                icon_map.insert((icon_name.to_string(), size, scale), entry);
                 theme_map.insert(theme.to_string(), icon_map);
             }
         }
     }
 
-    pub fn get(&self, theme: &str, size: u16, scale: u16, icon_name: &str) -> Option<PathBuf> {
+    pub fn get(&self, theme: &str, size: u16, scale: u16, icon_name: &str) -> CacheEntry {
         let theme_map = self.0.lock().unwrap();
 
         theme_map
             .get(theme)
             .map(|icon_map| icon_map.get(&(icon_name.to_string(), size, scale)))
             .and_then(|path| path.cloned())
+            .unwrap_or(CacheEntry::Unknown)
     }
 }