Add statistics server

proxy/stats.go

@@ -0,0 +1,58 @@
+package proxy
+
+import (
+	"encoding/json"
+	"net"
+	"net/http"
+	"strconv"
+	"sync/atomic"
+	"time"
+)
+
+type statsUptime time.Time
+
+func (s statsUptime) MarshalJSON() ([]byte, error) {
+	uptime := int(time.Since(time.Time(s)).Seconds())
+	return []byte(strconv.Itoa(uptime)), nil
+}
+
+type Stats struct {
+	AllConnections    uint64 `json:"all_connections"`
+	ActiveConnections uint32 `json:"active_connections"`
+	Traffic           struct {
+		Incoming uint64 `json:"incoming"`
+		Outgoing uint64 `json:"outgoing"`
+	} `json:"traffic"`
+	Uptime statsUptime `json:"uptime"`
+}
+
+func (s *Stats) newConnection() {
+	atomic.AddUint64(&s.AllConnections, 1)
+	atomic.AddUint32(&s.ActiveConnections, 1)
+}
+
+func (s *Stats) closeConnection() {
+	atomic.AddUint32(&s.ActiveConnections, ^uint32(0))
+}
+
+func (s *Stats) addIncomingTraffic(n int) {
+	atomic.AddUint64(&s.Traffic.Incoming, uint64(n))
+}
+
+func (s *Stats) addOutgoingTraffic(n int) {
+	atomic.AddUint64(&s.Traffic.Outgoing, uint64(n))
+}
+
+func (s *Stats) Serve(host net.IP, port uint16) {
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(s)
+	})
+
+	addr := net.JoinHostPort(host.String(), strconv.Itoa(int(port)))
+	http.ListenAndServe(addr, nil)
+}
+
+func NewStats() *Stats {
+	return &Stats{Uptime: statsUptime(time.Now())}
+}