add /nodes API for explorer (#585)

* add /nodes API for explorer

* Remove comment.

* pass pubkeys array pointer instead.

* pass function pointer to get nodeCount.

* rename to GetNumPeers

api/service/explorer/service.go

@@ -27,16 +27,18 @@ type Service struct {
 	router      *mux.Router
 	IP          string
 	Port        string
+	GetNumPeers func() int
 	storage     *Storage
 	server      *http.Server
 	messageChan chan *msg_pb.Message
 }
 
 // New returns explorer service.
-func New(selfPeer *p2p.Peer) *Service {
+func New(selfPeer *p2p.Peer, GetNumPeers func() int) *Service {
 	return &Service{
-		IP:   selfPeer.IP,
+		IP:          selfPeer.IP,
-		Port: selfPeer.Port,
+		Port:        selfPeer.Port,
+		GetNumPeers: GetNumPeers,
 	}
 }
 
@@ -89,6 +91,9 @@ func (s *Service) Run() *http.Server {
 	s.router.Path("/address").Queries("id", "{[0-9A-Fa-fx]*?}").HandlerFunc(s.GetExplorerAddress).Methods("GET")
 	s.router.Path("/address").HandlerFunc(s.GetExplorerAddress)
 
+	// Set up router for nodes.
+	s.router.Path("/nodes").HandlerFunc(s.GetExplorerNodes)
+
 	// Do serving now.
 	utils.GetLogInstance().Info("Listening on ", "port: ", GetExplorerPort(s.Port))
 	server := &http.Server{Addr: addr, Handler: s.router}
@@ -247,6 +252,12 @@ func (s *Service) GetExplorerAddress(w http.ResponseWriter, r *http.Request) {
 	json.NewEncoder(w).Encode(data.Address)
 }
 
+// GetExplorerNodes serves /nodes end-point.
+func (s *Service) GetExplorerNodes(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(s.GetNumPeers())
+}
+
 // NotifyService notify service
 func (s *Service) NotifyService(params map[string]interface{}) {
 	return

consensus/consensus.go

@@ -657,3 +657,8 @@ func (consensus *Consensus) SetLeaderPubKey(k []byte) error {
 func (consensus *Consensus) GetLeaderPubKey() *bls.PublicKey {
 	return consensus.leader.ConsensusPubKey
 }
+
+// GetNumPeers returns the length of PublicKeys
+func (consensus *Consensus) GetNumPeers() int {
+	return len(consensus.PublicKeys)
+}

node/service_setup.go

@@ -26,7 +26,7 @@ func (node *Node) setupForShardLeader() {
 	node.serviceManager.RegisterService(service.NetworkInfo, networkinfo.New(node.host, p2p.GroupIDBeacon, chanPeer, nil))
 
 	// Register explorer service.
-	node.serviceManager.RegisterService(service.SupportExplorer, explorer.New(&node.SelfPeer))
+	node.serviceManager.RegisterService(service.SupportExplorer, explorer.New(&node.SelfPeer, node.Consensus.GetNumPeers))
 	// Register consensus service.
 	node.serviceManager.RegisterService(service.Consensus, consensus.New(node.BlockChannel, node.Consensus, node.startConsensus))
 	// Register new block service.
@@ -67,7 +67,7 @@ func (node *Node) setupForBeaconLeader() {
 	// Register randomness service
 	node.serviceManager.RegisterService(service.Randomness, randomness.New(node.DRand))
 	// Register explorer service.
-	node.serviceManager.RegisterService(service.SupportExplorer, explorer.New(&node.SelfPeer))
+	node.serviceManager.RegisterService(service.SupportExplorer, explorer.New(&node.SelfPeer, node.Consensus.GetNumPeers))
 }
 
 func (node *Node) setupForBeaconValidator() {