cmd/syncthing, lib/relay: Fixes regarding stopping of services (#5293)

cmd/syncthing/usage_report.go

@@ -17,6 +17,7 @@ import (
 	"runtime"
 	"sort"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/syncthing/syncthing/lib/config"
@@ -326,6 +327,8 @@ type usageReportingService struct {
 	connectionsService *connections.Service
 	forceRun           chan struct{}
 	stop               chan struct{}
+	stopped            chan struct{}
+	stopMut            sync.RWMutex
 }
 
 func newUsageReportingService(cfg *config.Wrapper, model *model.Model, connectionsService *connections.Service) *usageReportingService {
@@ -335,7 +338,9 @@ func newUsageReportingService(cfg *config.Wrapper, model *model.Model, connectio
 		connectionsService: connectionsService,
 		forceRun:           make(chan struct{}),
 		stop:               make(chan struct{}),
+		stopped:            make(chan struct{}),
 	}
+	close(svc.stopped) // Not yet running, dont block on Stop()
 	cfg.Subscribe(svc)
 	return svc
 }
@@ -359,8 +364,16 @@ func (s *usageReportingService) sendUsageReport() error {
 }
 
 func (s *usageReportingService) Serve() {
+	s.stopMut.Lock()
 	s.stop = make(chan struct{})
+	s.stopped = make(chan struct{})
+	s.stopMut.Unlock()
 	t := time.NewTimer(time.Duration(s.cfg.Options().URInitialDelayS) * time.Second)
+	s.stopMut.RLock()
+	defer func() {
+		close(s.stopped)
+		s.stopMut.RUnlock()
+	}()
 	for {
 		select {
 		case <-s.stop:
@@ -387,14 +400,21 @@ func (s *usageReportingService) VerifyConfiguration(from, to config.Configuratio
 
 func (s *usageReportingService) CommitConfiguration(from, to config.Configuration) bool {
 	if from.Options.URAccepted != to.Options.URAccepted || from.Options.URUniqueID != to.Options.URUniqueID || from.Options.URURL != to.Options.URURL {
-		s.forceRun <- struct{}{}
+		s.stopMut.RLock()
+		select {
+		case s.forceRun <- struct{}{}:
+		case <-s.stop:
+		}
+		s.stopMut.RUnlock()
 	}
 	return true
 }
 
 func (s *usageReportingService) Stop() {
+	s.stopMut.RLock()
 	close(s.stop)
-	close(s.forceRun)
+	<-s.stopped
+	s.stopMut.RUnlock()
 }
 
 func (usageReportingService) String() string {

lib/relay/client/static.go

@@ -28,6 +28,7 @@ type staticClient struct {
 
 	stop    chan struct{}
 	stopped chan struct{}
+	stopMut sync.RWMutex
 
 	conn *tls.Conn
 
@@ -44,6 +45,8 @@ func newStaticClient(uri *url.URL, certs []tls.Certificate, invitations chan pro
 		invitations = make(chan protocol.SessionInvitation)
 	}
 
+	stopped := make(chan struct{})
+	close(stopped) // not yet started, don't block on Stop()
 	return &staticClient{
 		uri:         uri,
 		invitations: invitations,
@@ -56,7 +59,8 @@ func newStaticClient(uri *url.URL, certs []tls.Certificate, invitations chan pro
 		connectTimeout: timeout,
 
 		stop:    make(chan struct{}),
-		stopped: make(chan struct{}),
+		stopped: stopped,
+		stopMut: sync.NewRWMutex(),
 
 		mut: sync.NewRWMutex(),
 	}
@@ -64,8 +68,10 @@ func newStaticClient(uri *url.URL, certs []tls.Certificate, invitations chan pro
 
 func (c *staticClient) Serve() {
 	defer c.cleanup()
+	c.stopMut.Lock()
 	c.stop = make(chan struct{})
 	c.stopped = make(chan struct{})
+	c.stopMut.Unlock()
 	defer close(c.stopped)
 
 	if err := c.connect(); err != nil {
@@ -104,6 +110,8 @@ func (c *staticClient) Serve() {
 
 	timeout := time.NewTimer(c.messageTimeout)
 
+	c.stopMut.RLock()
+	defer c.stopMut.RUnlock()
 	for {
 		select {
 		case message := <-messages:
@@ -169,12 +177,10 @@ func (c *staticClient) Serve() {
 }
 
 func (c *staticClient) Stop() {
-	if c.stop == nil {
-		return
-	}
-
+	c.stopMut.RLock()
 	close(c.stop)
 	<-c.stopped
+	c.stopMut.RUnlock()
 }
 
 func (c *staticClient) StatusOK() bool {