hls: fix toggling hlsAlwaysRemux after server is started (#4503)

When hlsAlwaysRemux was switched from false to true, through API or hot
reloading, muxers of existing paths were not created. This fixes the
issue.

internal/servers/rtmp/server.go

@@ -7,6 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"reflect"
 	"sort"
 	"sync"
 
@@ -24,6 +25,10 @@ import (
 // ErrConnNotFound is returned when a connection is not found.
 var ErrConnNotFound = errors.New("connection not found")
 
+func interfaceIsEmpty(i interface{}) bool {
+	return reflect.ValueOf(i).Kind() != reflect.Ptr || reflect.ValueOf(i).IsNil()
+}
+
 type serverAPIConnsListRes struct {
 	data *defs.APIRTMPConnList
 	err  error
@@ -52,6 +57,11 @@ type serverAPIConnsKickReq struct {
 	res  chan serverAPIConnsKickRes
 }
 
+type serverMetrics interface {
+	SetRTMPSServer(defs.APIRTMPServer)
+	SetRTMPServer(defs.APIRTMPServer)
+}
+
 type serverPathManager interface {
 	AddPublisher(req defs.PathAddPublisherReq) (defs.Path, error)
 	AddReader(req defs.PathAddReaderReq) (defs.Path, *stream.Stream, error)
@@ -74,6 +84,7 @@ type Server struct {
 	RunOnConnectRestart bool
 	RunOnDisconnect     string
 	ExternalCmdPool     *externalcmd.Pool
+	Metrics             serverMetrics
 	PathManager         serverPathManager
 	Parent              serverParent
 
@@ -140,6 +151,14 @@ func (s *Server) Initialize() error {
 	s.wg.Add(1)
 	go s.run()
 
+	if !interfaceIsEmpty(s.Metrics) {
+		if s.IsTLS {
+			s.Metrics.SetRTMPSServer(s)
+		} else {
+			s.Metrics.SetRTMPServer(s)
+		}
+	}
+
 	return nil
 }
 
@@ -157,8 +176,18 @@ func (s *Server) Log(level logger.Level, format string, args ...interface{}) {
 // Close closes the server.
 func (s *Server) Close() {
 	s.Log(logger.Info, "listener is closing")
+
+	if !interfaceIsEmpty((s.Metrics)) {
+		if s.IsTLS {
+			s.Metrics.SetRTMPSServer(nil)
+		} else {
+			s.Metrics.SetRTMPServer(nil)
+		}
+	}
+
 	s.ctxCancel()
 	s.wg.Wait()
+
 	if s.loader != nil {
 		s.loader.Close()
 	}