ethstats: use timer instead of time.Sleep #20924 #21404 (#1442)

* ethstats: use timer instead of time.Sleep #20924

* ethstats: avoid concurrent write on websocket, fixes #21403 #21404

ethstats/ethstats.go

@@ -261,8 +261,15 @@ func (s *Service) loop() {
 	if !strings.Contains(path, "://") {
 		urls = []string{"wss://" + path, "ws://" + path}
 	}
+
+	errTimer := time.NewTimer(0)
+	defer errTimer.Stop()
 	// Loop reporting until termination
 	for {
+		select {
+		case <-quitCh:
+			return
+		case <-errTimer.C:
 			// Establish a websocket connection to the server on any supported URL
 			var (
 				conn *connWrapper
@@ -273,22 +280,22 @@ func (s *Service) loop() {
 			header.Set("origin", "http://localhost")
 			for _, url := range urls {
 				c, _, e := dialer.Dial(url, header)
-			err = e
+				if e == nil {
-			if err == nil {
 					conn = newConnectionWrapper(c)
 					break
 				}
+				err = e
 			}
 			if err != nil {
 				log.Warn("Stats server unreachable", "err", err)
-			time.Sleep(10 * time.Second)
+				errTimer.Reset(10 * time.Second)
 				continue
 			}
 			// Authenticate the client with the server
 			if err = s.login(conn); err != nil {
 				log.Warn("Stats login failed", "err", err)
 				conn.Close()
-			time.Sleep(10 * time.Second)
+				errTimer.Reset(10 * time.Second)
 				continue
 			}
 			go s.readLoop(conn)
@@ -297,11 +304,11 @@ func (s *Service) loop() {
 			if err = s.report(conn); err != nil {
 				log.Warn("Initial stats report failed", "err", err)
 				conn.Close()
+				errTimer.Reset(0)
 				continue
 			}
 			// Keep sending status updates until the connection breaks
 			fullReport := time.NewTicker(15 * time.Second)
-		defer fullReport.Stop()
 
 			for err == nil {
 				select {
@@ -341,6 +348,7 @@ func (s *Service) loop() {
 			conn.Close()
 		}
 	}
+}
 
 // readLoop loops as long as the connection is alive and retrieves data packets
 // from the network socket. If any of them match an active request, it forwards