Add get_call_log_length helper to router-middleware

contracts/router-middleware/src/lib.rs

@@ -498,6 +498,19 @@ impl RouterMiddleware {
             .get(&DataKey::CallLog(route))
             .unwrap_or(Vec::new(&env))
     }
+
+    /// Get the number of call log entries for a route.
+    ///
+    /// More efficient than loading the full call log when callers only need
+    /// the current retained length.
+    pub fn get_call_log_length(env: Env, route: String) -> u32 {
+        env.storage()
+            .instance()
+            .get::<DataKey, Vec<CallLogEntry>>(&DataKey::CallLog(route))
+            .map(|log| log.len())
+            .unwrap_or(0)
+    }
+
     /// Get rate limit state for a caller on a specific route.
     ///
     /// Returns the current [`RateLimitState`] for `caller` on `route`, which includes the
@@ -821,6 +834,43 @@ mod tests {
         client.post_call(&caller, &route, &false);
     }
 
+    #[test]
+    fn test_get_call_log_length_zero_before_calls() {
+        let (env, admin, client) = setup();
+        let route = String::from_str(&env, "oracle/get_price");
+        client.configure_route(&admin, &route, &0, &0, &true, &0, &0, &3);
+
+        assert_eq!(client.get_call_log_length(&route), 0);
+    }
+
+    #[test]
+    fn test_get_call_log_length_matches_get_call_log() {
+        let (env, admin, client) = setup();
+        let route = String::from_str(&env, "oracle/get_price");
+        let caller = Address::generate(&env);
+        client.configure_route(&admin, &route, &0, &0, &true, &0, &0, &5);
+
+        client.post_call(&caller, &route, &true);
+        client.post_call(&caller, &route, &false);
+
+        assert_eq!(client.get_call_log_length(&route), client.get_call_log(&route).len());
+    }
+
+    #[test]
+    fn test_get_call_log_length_respects_retention() {
+        let (env, admin, client) = setup();
+        let route = String::from_str(&env, "oracle/get_price");
+        let caller = Address::generate(&env);
+        client.configure_route(&admin, &route, &0, &0, &true, &0, &0, &2);
+
+        client.post_call(&caller, &route, &true);
+        client.post_call(&caller, &route, &false);
+        client.post_call(&caller, &route, &true);
+
+        assert_eq!(client.get_call_log_length(&route), 2);
+        assert_eq!(client.get_call_log(&route).len(), 2);
+    }
+
     #[test]
     fn test_rate_limit_isolated_per_route() {
         let (env, admin, client) = setup();