优化mongo，封装count逻辑，处理objectId

consts/config.go

@@ -0,0 +1,19 @@
+package consts
+
+// 默认配置值
+const (
+	DefaultTimeout    = 5000 // 默认超时时间(毫秒)
+	DefaultRetryCount = 3    // 默认重试次数
+	DefaultPriority   = 1    // 默认优先级
+)
+
+// 错误消息
+const (
+	ErrAdSourceNotFound     = "广告源不存在"
+	ErrAdSourceNameExists   = "广告源名称已存在"
+	ErrAdSourceCodeExists   = "广告源编码已存在"
+	ErrAdSourceInactive     = "广告源非活跃状态"
+	ErrAdSourceUnhealthy    = "广告源健康状态异常"
+	ErrRateLimitExceeded    = "请求频率超限"
+	ErrInvalidConfiguration = "配置参数无效"
+)