增加对数据库操作的统计命令：edge-node dbstat/减少几个不必要的查询操作

internal/utils/dbs/query_label.go

@@ -0,0 +1,24 @@
+// Copyright 2022 Liuxiangchao iwind.liu@gmail.com. All rights reserved.
+
+package dbs
+
+import "time"
+
+type QueryLabel struct {
+	manager *QueryStatManager
+	query   string
+	before  time.Time
+}
+
+func NewQueryLabel(manager *QueryStatManager, query string) *QueryLabel {
+	return &QueryLabel{
+		manager: manager,
+		query:   query,
+		before:  time.Now(),
+	}
+}
+
+func (this *QueryLabel) End() {
+	var cost = time.Since(this.before).Seconds()
+	this.manager.AddCost(this.query, cost)
+}