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/response.go

@@ -0,0 +1,35 @@
+package serializer
+
+import (
+	"bytes"
+	"encoding/base64"
+	"encoding/gob"
+)
+
+// 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"`
+}
+
+// NewResponseWithGobData 返回Data字段使用gob编码的Response
+func NewResponseWithGobData(data interface{}) Response {
+	var w bytes.Buffer
+	encoder := gob.NewEncoder(&w)
+	if err := encoder.Encode(data); err != nil {
+		return Err(CodeInternalSetting, "无法编码返回结果", err)
+	}
+
+	return Response{Data: w.Bytes()}
+}
+
+// GobDecode 将 Response 正文解码至目标指针
+func (r *Response) GobDecode(target interface{}) {
+	src := r.Data.(string)
+	raw := make([]byte, len(src)*len(src)/base64.StdEncoding.DecodedLen(len(src)))
+	base64.StdEncoding.Decode(raw, []byte(src))
+	decoder := gob.NewDecoder(bytes.NewBuffer(raw))
+	decoder.Decode(target)
+}