Minor optimization in StringKey, making it from an Arc<String> into an Arc<str>

src/utils/string_key.rs

@@ -8,12 +8,12 @@ use std::sync::{Arc, Mutex, Weak};
 /// `charmander` == `Charmander`.
 #[derive(Clone, Debug)]
 pub struct StringKey {
-    str: Arc<String>,
+    str: Arc<str>,
     hash: u32,
 }
 
 lazy_static::lazy_static! {
-    static ref STRING_CACHE: Mutex<HashMap<u32, Weak<String>>> = Mutex::new(HashMap::new());
+    static ref STRING_CACHE: Mutex<HashMap<u32, Weak<str>>> = Mutex::new(HashMap::new());
 }
 
 impl StringKey {
@@ -49,7 +49,7 @@ impl StringKey {
             }
         }
         let v = Self {
-            str: Arc::new(s.to_string()),
+            str: s.into(),
             hash,
         };
         cache.insert(hash, Arc::downgrade(&v.str));
@@ -57,7 +57,7 @@ impl StringKey {
     }
 
     pub fn str(&self) -> &str {
-        self.str.as_str()
+        &self.str
     }
 
     pub fn hash(&self) -> u32 {