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/cluster/node.go

@@ -0,0 +1,60 @@
+package cluster
+
+import (
+	model "github.com/cloudreve/Cloudreve/v3/models"
+	"github.com/cloudreve/Cloudreve/v3/pkg/aria2/common"
+	"github.com/cloudreve/Cloudreve/v3/pkg/auth"
+	"github.com/cloudreve/Cloudreve/v3/pkg/serializer"
+)
+
+type Node interface {
+	// Init a node from database model
+	Init(node *model.Node)
+
+	// Check if given feature is enabled
+	IsFeatureEnabled(feature string) bool
+
+	// Subscribe node status change to a callback function
+	SubscribeStatusChange(callback func(isActive bool, id uint))
+
+	// Ping the node
+	Ping(req *serializer.NodePingReq) (*serializer.NodePingResp, error)
+
+	// Returns if the node is active
+	IsActive() bool
+
+	// Get instances for aria2 calls
+	GetAria2Instance() common.Aria2
+
+	// Returns unique id of this node
+	ID() uint
+
+	// Kill node and recycle resources
+	Kill()
+
+	// Returns if current node is master node
+	IsMater() bool
+
+	// Get auth instance used to check RPC call from slave to master
+	MasterAuthInstance() auth.Auth
+
+	// Get auth instance used to check RPC call from master to slave
+	SlaveAuthInstance() auth.Auth
+
+	// Get node DB model
+	DBModel() *model.Node
+}
+
+// Create new node from DB model
+func NewNodeFromDBModel(node *model.Node) Node {
+	switch node.Type {
+	case model.SlaveNodeType:
+		slave := &SlaveNode{}
+		slave.Init(node)
+		return slave
+	default:
+		master := &MasterNode{}
+		master.Init(node)
+		return master
+	}
+}