Merge pull request #244 from Notifiarr/dn2_faster

Fewer hot path allocations

Author: davidnewhall

pkg/webserver/functions.go

@@ -18,6 +18,27 @@ const (
 	keyPosition = 5        // example: /api/v1/route/method/apikey
 )
 
+// pathSegment returns the idx-th element of strings.Split(pathStr, "/") using strings.SplitSeq
+// so the full split slice is not allocated.
+func pathSegment(pathStr string, idx int) string {
+	segIdx := 0
+
+	for seg := range strings.SplitSeq(pathStr, "/") {
+		if segIdx == idx {
+			before, _, found := strings.Cut(seg, "?")
+			if found {
+				return before
+			}
+
+			return seg
+		}
+
+		segIdx++
+	}
+
+	return ""
+}
+
 type responseWrapper struct {
 	http.ResponseWriter
 
@@ -68,12 +89,23 @@ func (s *server) parseAPIKey(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
 		key := req.Header.Get("X-Api-Key")
 		if len(key) != keyLength {
-			if uri := strings.Split(req.Header.Get("X-Original-Uri"), "/"); len(uri) > keyPosition {
-				key = strings.Split(uri[keyPosition], "?")[0]
-			}
+			key = pathSegment(req.Header.Get("X-Original-Uri"), keyPosition)
+		}
+
+		pooled := s.apiKeyVarsPool.Get()
+
+		urlVars, ok := pooled.(map[string]string)
+		if !ok {
+			urlVars = make(map[string]string, 1)
 		}
 
-		req = mux.SetURLVars(req, map[string]string{apiKey: key})
+		urlVars[apiKey] = key
+		req = mux.SetURLVars(req, urlVars)
+
+		defer func() {
+			delete(urlVars, apiKey)
+			s.apiKeyVarsPool.Put(urlVars)
+		}()
 
 		if len(key) != keyLength {
 			s.metrics.HTTPRequests.WithLabelValues(exp.HTTPEventInvalidKey).Inc()

pkg/webserver/handlers_nginx.go

@@ -23,20 +23,22 @@ type keyReq struct {
 }
 
 func (s *server) handleServer(resp http.ResponseWriter, req *http.Request) {
+	key := req.Header.Get("X-Server")
 	s.handleGetAny(resp, req, &keyReq{
 		label: "servers",
-		key:   req.Header.Get("X-Server"),
-		cache: s.servers.Get(req.Header.Get("X-Server")),
+		key:   key,
+		cache: s.servers.Get(key),
 		get:   s.ui.GetServer,
 		save:  s.servers.Save,
 	})
 }
 
 func (s *server) handleGetKey(resp http.ResponseWriter, req *http.Request) {
+	key := mux.Vars(req)[apiKey]
 	s.handleGetAny(resp, req, &keyReq{
 		label: "users",
-		key:   mux.Vars(req)[apiKey],
-		cache: s.users.Get(mux.Vars(req)[apiKey]),
+		key:   key,
+		cache: s.users.Get(key),
 		get:   s.ui.GetInfo,
 		save:  s.users.Save,
 	})

pkg/webserver/start.go

@@ -59,6 +59,8 @@ type server struct {
 	// noAuthMu protects NoAuthPaths on the embedded Config (RequiresAPIKey, reload, showConfig).
 	noAuthMu sync.RWMutex
 	metrics  *exp.Metrics
+	// apiKeyVarsPool backs mux.SetURLVars in parseAPIKey (avoids a map alloc per request).
+	apiKeyVarsPool sync.Pool
 }
 
 // ErrNoSQLConfig is returned if no mysql config is present.
@@ -123,6 +125,8 @@ func Start(config *Config) error {
 }
 
 func (s *server) start() error {
+	s.apiKeyVarsPool = sync.Pool{New: func() any { return make(map[string]string, 1) }}
+
 	s.users = cache.New(cache.Config{PruneInterval: pruneInterval, RequestAccuracy: time.Second})
 	defer s.users.Stop(false)