WriteHeader should be called once

Signed-off-by: Evgeniy Kulikov <kim@nspcc.ru>

api/metrics/api.go

@@ -41,10 +41,10 @@ type (
 	}
 
 	responseWrapper struct {
+		sync.Once
 		http.ResponseWriter
 
 		statusCode int
-		headWritten bool
 		startTime  time.Time
 	}
 )
@@ -202,12 +202,10 @@ func (st *HTTPStats) updateStats(api string, w http.ResponseWriter, r *http.Requ
 
 // WriteHeader - writes http status code
 func (w *responseWrapper) WriteHeader(code int) {
-	if !w.headWritten {
+	w.Do(func() {
 		w.statusCode = code
-		w.headWritten = true
-
 		w.ResponseWriter.WriteHeader(code)
-	}
+	})
 }
 
 // Flush - Calls the underlying Flush.

api/router.go

@@ -3,6 +3,7 @@ package api
 import (
 	"context"
 	"net/http"
+	"sync"
 
 	"github.com/google/uuid"
 	"github.com/gorilla/mux"
@@ -81,7 +82,9 @@ type (
 	mimeType string
 
 	logResponseWriter struct {
+		sync.Once
 		http.ResponseWriter
+
 		statusCode int
 	}
 )
@@ -100,8 +103,10 @@ const (
 var _ = logErrorResponse
 
 func (lrw *logResponseWriter) WriteHeader(code int) {
+	lrw.Do(func() {
 		lrw.statusCode = code
 		lrw.ResponseWriter.WriteHeader(code)
+	})
 }
 
 func setRequestID(h http.Handler) http.Handler {
@@ -139,12 +144,14 @@ func logErrorResponse(l *zap.Logger) mux.MiddlewareFunc {
 					zap.Int("status", lw.statusCode),
 					zap.String("method", mux.CurrentRoute(r).GetName()),
 					zap.String("description", http.StatusText(lw.statusCode)))
-			} else {
+
+				return
+			}
+
 			l.Info("call method",
 				zap.Int("status", lw.statusCode),
 				zap.String("method", mux.CurrentRoute(r).GetName()),
 				zap.String("description", http.StatusText(lw.statusCode)))
-			}
 		})
 	}
 }