Merge pull request #1943 from xiang90/fix_streamSrv

sender: set strmSrv to nil after stoping it

rafthttp/sender.go

@@ -98,10 +98,11 @@ type sender struct {
 	strmCln     *streamClient
 	batcher     *Batcher
 	propBatcher *ProposalBatcher
-	strmSrv     *streamServer
-	strmSrvMu   sync.Mutex
 	q           chan []byte
 
+	strmSrvMu sync.Mutex
+	strmSrv   *streamServer
+
 	// wait for the handling routines
 	wg sync.WaitGroup
 
@@ -124,6 +125,7 @@ func (s *sender) StartStreaming(w WriteFlusher, to types.ID, term uint64) (<-cha
 		}
 		// stop the existing one
 		s.strmSrv.stop()
+		s.strmSrv = nil
 	}
 	s.strmSrv = startStreamServer(w, to, term, s.fs)
 	return s.strmSrv.stopNotify(), nil
@@ -199,6 +201,7 @@ func (s *sender) Stop() {
 	s.strmSrvMu.Lock()
 	if s.strmSrv != nil {
 		s.strmSrv.stop()
+		s.strmSrv = nil
 	}
 	s.strmSrvMu.Unlock()
 	if s.strmCln != nil {