⚙️ refactor: replace oncecell with oncelock from std library (#180)(#178)

src/results/user_agent.rs

@@ -1,28 +1,32 @@
 //! This module provides the functionality to generate random user agent string.
 
+use std::sync::OnceLock;
+
 use fake_useragent::{Browsers, UserAgents, UserAgentsBuilder};
 
-static USER_AGENTS: once_cell::sync::Lazy<UserAgents> = once_cell::sync::Lazy::new(|| {
-    UserAgentsBuilder::new()
-        .cache(false)
-        .dir("/tmp")
-        .thread(1)
-        .set_browsers(
-            Browsers::new()
-                .set_chrome()
-                .set_safari()
-                .set_edge()
-                .set_firefox()
-                .set_mozilla(),
-        )
-        .build()
-});
+static USER_AGENTS: OnceLock<UserAgents> = OnceLock::new();
 
 /// A function to generate random user agent to improve privacy of the user.
 ///
 /// # Returns
 ///
 /// A randomly generated user agent string.
-pub fn random_user_agent() -> String {
-    USER_AGENTS.random().to_string()
+pub fn random_user_agent() -> &'static str {
+    USER_AGENTS
+        .get_or_init(|| {
+            UserAgentsBuilder::new()
+                .cache(false)
+                .dir("/tmp")
+                .thread(1)
+                .set_browsers(
+                    Browsers::new()
+                        .set_chrome()
+                        .set_safari()
+                        .set_edge()
+                        .set_firefox()
+                        .set_mozilla(),
+                )
+                .build()
+        })
+        .random()
 }