add prometheus-middlewares for http and ws endpoint

pkg/prom/middleware.go

@@ -0,0 +1,35 @@
+package prom
+
+import (
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func HTTPMiddleware(next http.Handler) http.Handler {
+	if !metrics {
+		return next
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		httpCount.Inc()
+
+		timer := prometheus.NewTimer(httpDuration)
+		next.ServeHTTP(w, r)
+		timer.ObserveDuration()
+	})
+}
+
+func WSMiddleware(next http.Handler) http.Handler {
+	if !metrics {
+		return next
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		wsCount.Inc()
+
+		timer := prometheus.NewTimer(wsDuration)
+		next.ServeHTTP(w, r)
+		timer.ObserveDuration()
+	})
+}