fix(rustproxy-routing): reduce hot-path allocations in routing, metrics, and proxy protocol handling

rust/crates/rustproxy-http/src/proxy_service.rs

@@ -399,11 +399,19 @@ impl HttpProxyService {
         let path = req.uri().path().to_string();
         let method = req.method().clone();
 
-        // Extract headers for matching
-        let headers: HashMap<String, String> = req.headers()
-            .iter()
-            .map(|(k, v)| (k.to_string(), v.to_str().unwrap_or("").to_string()))
-            .collect();
+        // Extract headers for matching — only allocate the HashMap if any route
+        // on this port actually uses header matching. Most deployments don't,
+        // so this saves ~20-30 String allocations per request.
+        let current_rm = self.route_manager.load();
+        let needs_headers = current_rm.any_route_has_headers(port);
+        let headers: Option<HashMap<String, String>> = if needs_headers {
+            Some(req.headers()
+                .iter()
+                .map(|(k, v)| (k.to_string(), v.to_str().unwrap_or("").to_string()))
+                .collect())
+        } else {
+            None
+        };
 
         debug!("HTTP {} {} (host: {:?}) from {}", method, path, host, peer_addr);
 
@@ -414,19 +422,19 @@ impl HttpProxyService {
             }
         }
 
-        // Match route
+        // Match route (current_rm already loaded above for headers check)
+        let ip_string = peer_addr.ip().to_string();
         let ctx = rustproxy_routing::MatchContext {
             port,
             domain: host.as_deref(),
             path: Some(&path),
-            client_ip: Some(&peer_addr.ip().to_string()),
+            client_ip: Some(&ip_string),
             tls_version: None,
-            headers: Some(&headers),
+            headers: headers.as_ref(),
             is_tls: false,
             protocol: Some("http"),
         };
 
-        let current_rm = self.route_manager.load();
         let route_match = match current_rm.find_route(&ctx) {
             Some(rm) => rm,
             None => {
@@ -436,7 +444,7 @@ impl HttpProxyService {
         };
 
         let route_id = route_match.route.id.as_deref();
-        let ip_str = peer_addr.ip().to_string();
+        let ip_str = ip_string; // reuse from above (avoid redundant to_string())
         self.metrics.record_http_request();
 
         // Apply request filters (IP check, rate limiting, auth)