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/pool.go

@@ -0,0 +1,176 @@
+package cluster
+
+import (
+	model "github.com/cloudreve/Cloudreve/v3/models"
+	"github.com/cloudreve/Cloudreve/v3/pkg/balancer"
+	"github.com/cloudreve/Cloudreve/v3/pkg/util"
+	"sync"
+)
+
+var Default *NodePool
+
+// 需要分类的节点组
+var featureGroup = []string{"aria2"}
+
+// Pool 节点池
+type Pool interface {
+	// Returns active node selected by given feature and load balancer
+	BalanceNodeByFeature(feature string, lb balancer.Balancer) (error, Node)
+
+	// Returns node by ID
+	GetNodeByID(id uint) Node
+
+	// Add given node into pool. If node existed, refresh node.
+	Add(node *model.Node)
+
+	// Delete and kill node from pool by given node id
+	Delete(id uint)
+}
+
+// NodePool 通用节点池
+type NodePool struct {
+	active   map[uint]Node
+	inactive map[uint]Node
+
+	featureMap map[string][]Node
+
+	lock sync.RWMutex
+}
+
+// Init 初始化从机节点池
+func Init() {
+	Default = &NodePool{
+		featureMap: make(map[string][]Node),
+	}
+	if err := Default.initFromDB(); err != nil {
+		util.Log().Warning("节点池初始化失败, %s", err)
+	}
+}
+
+func (pool *NodePool) buildIndexMap() {
+	pool.lock.Lock()
+	for _, feature := range featureGroup {
+		pool.featureMap[feature] = make([]Node, 0)
+	}
+
+	for _, v := range pool.active {
+		for _, feature := range featureGroup {
+			if v.IsFeatureEnabled(feature) {
+				pool.featureMap[feature] = append(pool.featureMap[feature], v)
+			}
+		}
+	}
+	pool.lock.Unlock()
+}
+
+func (pool *NodePool) GetNodeByID(id uint) Node {
+	pool.lock.RLock()
+	defer pool.lock.RUnlock()
+
+	if node, ok := pool.active[id]; ok {
+		return node
+	}
+
+	return pool.inactive[id]
+}
+
+func (pool *NodePool) nodeStatusChange(isActive bool, id uint) {
+	util.Log().Debug("从机节点 [ID=%d] 状态变更 [Active=%t]", id, isActive)
+	pool.lock.Lock()
+	if isActive {
+		node := pool.inactive[id]
+		delete(pool.inactive, id)
+		pool.active[id] = node
+	} else {
+		node := pool.active[id]
+		delete(pool.active, id)
+		pool.inactive[id] = node
+	}
+	pool.lock.Unlock()
+
+	pool.buildIndexMap()
+}
+
+func (pool *NodePool) initFromDB() error {
+	nodes, err := model.GetNodesByStatus(model.NodeActive)
+	if err != nil {
+		return err
+	}
+
+	pool.lock.Lock()
+	pool.active = make(map[uint]Node)
+	pool.inactive = make(map[uint]Node)
+	for i := 0; i < len(nodes); i++ {
+		pool.add(&nodes[i])
+	}
+	pool.lock.Unlock()
+
+	pool.buildIndexMap()
+	return nil
+}
+
+func (pool *NodePool) add(node *model.Node) {
+	newNode := NewNodeFromDBModel(node)
+	if newNode.IsActive() {
+		pool.active[node.ID] = newNode
+	} else {
+		pool.inactive[node.ID] = newNode
+	}
+
+	// 订阅节点状态变更
+	newNode.SubscribeStatusChange(func(isActive bool, id uint) {
+		pool.nodeStatusChange(isActive, id)
+	})
+}
+
+func (pool *NodePool) Add(node *model.Node) {
+	pool.lock.Lock()
+	defer pool.buildIndexMap()
+	defer pool.lock.Unlock()
+
+	if _, ok := pool.active[node.ID]; ok {
+		// TODO: refresh node
+		return
+	}
+
+	if _, ok := pool.inactive[node.ID]; ok {
+		return
+	}
+
+	pool.add(node)
+}
+
+func (pool *NodePool) Delete(id uint) {
+	pool.lock.Lock()
+	defer pool.buildIndexMap()
+	defer pool.lock.Unlock()
+
+	if node, ok := pool.active[id]; ok {
+		node.Kill()
+		delete(pool.active, id)
+		return
+	}
+
+	if node, ok := pool.inactive[id]; ok {
+		node.Kill()
+		delete(pool.inactive, id)
+		return
+	}
+
+}
+
+// BalanceNodeByFeature 根据 feature 和 LoadBalancer 取出节点
+func (pool *NodePool) BalanceNodeByFeature(feature string, lb balancer.Balancer) (error, Node) {
+	pool.lock.RLock()
+	defer pool.lock.RUnlock()
+	if nodes, ok := pool.featureMap[feature]; ok {
+		err, res := lb.NextPeer(nodes)
+		if err == nil {
+			return nil, res.(Node)
+		}
+
+		return err, nil
+	}
+
+	return ErrFeatureNotExist, nil
+}