Feat: aria2 download and transfer in slave node (#1040)

* Feat: retrieve nodes from data table

* Feat: master node ping slave node in REST API

* Feat: master send scheduled ping request

* Feat: inactive nodes recover loop

* Modify: remove database operations from aria2 RPC caller implementation

* Feat: init aria2 client in master node

* Feat: Round Robin load balancer

* Feat: create and monitor aria2 task in master node

* Feat: salve receive and handle heartbeat

* Fix: Node ID will be 0 in download record generated in older version

* Feat: sign request headers with all `X-` prefix

* Feat: API call to slave node will carry meta data in headers

* Feat: call slave aria2 rpc method from master

* Feat: get slave aria2 task status
Feat: encode slave response data using gob

* Feat: aria2 callback to master node / cancel or select task to slave node

* Fix: use dummy aria2 client when caller initialize failed in master node

* Feat: slave aria2 status event callback / salve RPC auth

* Feat: prototype for slave driven filesystem

* Feat: retry for init aria2 client in master node

* Feat: init request client with global options

* Feat: slave receive async task from master

* Fix: competition write in request header

* Refactor: dependency initialize order

* Feat: generic message queue implementation

* Feat: message queue implementation

* Feat: master waiting slave transfer result

* Feat: slave transfer file in stateless policy

* Feat: slave transfer file in slave policy

* Feat: slave transfer file in local policy

* Feat: slave transfer file in OneDrive policy

* Fix: failed to initialize update checker http client

* Feat: list slave nodes for dashboard

* Feat: test aria2 rpc connection in slave

* Feat: add and save node

* Feat: add and delete node in node pool

* Fix: temp file cannot be removed when aria2 task fails

* Fix: delete node in admin panel

* Feat: edit node and get node info

* Modify: delete unused settings

pkg/serializer/error.go

@@ -1,14 +1,9 @@
 package serializer
 
-import "github.com/gin-gonic/gin"
-
-// Response 基础序列化器
-type Response struct {
-	Code  int         `json:"code"`
-	Data  interface{} `json:"data,omitempty"`
-	Msg   string      `json:"msg"`
-	Error string      `json:"error,omitempty"`
-}
+import (
+	"errors"
+	"github.com/gin-gonic/gin"
+)
 
 // AppError 应用错误，实现了error接口
 type AppError struct {
@@ -17,7 +12,7 @@ type AppError struct {
 	RawError error
 }
 
-// NewError 返回新的错误对象 todo:测试 还有下面的
+// NewError 返回新的错误对象
 func NewError(code int, msg string, err error) AppError {
 	return AppError{
 		Code:     code,
@@ -26,6 +21,15 @@ func NewError(code int, msg string, err error) AppError {
 	}
 }
 
+// NewErrorFromResponse 从 serializer.Response 构建错误
+func NewErrorFromResponse(resp *Response) AppError {
+	return AppError{
+		Code:     resp.Code,
+		Msg:      resp.Msg,
+		RawError: errors.New(resp.Error),
+	}
+}
+
 // WithError 将应用error携带标准库中的error
 func (err *AppError) WithError(raw error) AppError {
 	err.RawError = raw
@@ -66,6 +70,8 @@ const (
 	CodeGroupNotAllowed = 40007
 	// CodeAdminRequired 非管理用户组
 	CodeAdminRequired = 40008
+	// CodeMasterNotFound 主机节点未注册
+	CodeMasterNotFound = 40009
 	// CodeDBError 数据库操作失败
 	CodeDBError = 50001
 	// CodeEncryptError 加密失败