lib: Ensure timely service termination (fixes #5860) (#5863)

lib/nat/service.go

@@ -14,17 +14,21 @@ import (
 	stdsync "sync"
 	"time"
 
+	"github.com/thejerf/suture"
+
 	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/sync"
+	"github.com/syncthing/syncthing/lib/util"
 )
 
 // Service runs a loop for discovery of IGDs (Internet Gateway Devices) and
 // setup/renewal of a port mapping.
 type Service struct {
-	id   protocol.DeviceID
-	cfg  config.Wrapper
-	stop chan struct{}
+	suture.Service
+
+	id  protocol.DeviceID
+	cfg config.Wrapper
 
 	mappings []*Mapping
 	timer    *time.Timer
@@ -32,27 +36,28 @@ type Service struct {
 }
 
 func NewService(id protocol.DeviceID, cfg config.Wrapper) *Service {
-	return &Service{
+	s := &Service{
 		id:  id,
 		cfg: cfg,
 
 		timer: time.NewTimer(0),
 		mut:   sync.NewRWMutex(),
 	}
+	s.Service = util.AsService(s.serve)
+	return s
 }
 
-func (s *Service) Serve() {
+func (s *Service) serve(stop chan struct{}) {
 	announce := stdsync.Once{}
 
 	s.mut.Lock()
 	s.timer.Reset(0)
-	s.stop = make(chan struct{})
 	s.mut.Unlock()
 
 	for {
 		select {
 		case <-s.timer.C:
-			if found := s.process(); found != -1 {
+			if found := s.process(stop); found != -1 {
 				announce.Do(func() {
 					suffix := "s"
 					if found == 1 {
@@ -61,7 +66,7 @@ func (s *Service) Serve() {
 					l.Infoln("Detected", found, "NAT service"+suffix)
 				})
 			}
-		case <-s.stop:
+		case <-stop:
 			s.timer.Stop()
 			s.mut.RLock()
 			for _, mapping := range s.mappings {
@@ -73,7 +78,7 @@ func (s *Service) Serve() {
 	}
 }
 
-func (s *Service) process() int {
+func (s *Service) process(stop chan struct{}) int {
 	// toRenew are mappings which are due for renewal
 	// toUpdate are the remaining mappings, which will only be updated if one of
 	// the old IGDs has gone away, or a new IGD has appeared, but only if we
@@ -115,25 +120,19 @@ func (s *Service) process() int {
 		return -1
 	}
 
-	nats := discoverAll(time.Duration(s.cfg.Options().NATRenewalM)*time.Minute, time.Duration(s.cfg.Options().NATTimeoutS)*time.Second)
+	nats := discoverAll(time.Duration(s.cfg.Options().NATRenewalM)*time.Minute, time.Duration(s.cfg.Options().NATTimeoutS)*time.Second, stop)
 
 	for _, mapping := range toRenew {
-		s.updateMapping(mapping, nats, true)
+		s.updateMapping(mapping, nats, true, stop)
 	}
 
 	for _, mapping := range toUpdate {
-		s.updateMapping(mapping, nats, false)
+		s.updateMapping(mapping, nats, false, stop)
 	}
 
 	return len(nats)
 }
 
-func (s *Service) Stop() {
-	s.mut.RLock()
-	close(s.stop)
-	s.mut.RUnlock()
-}
-
 func (s *Service) NewMapping(protocol Protocol, ip net.IP, port int) *Mapping {
 	mapping := &Mapping{
 		protocol: protocol,
@@ -178,17 +177,17 @@ func (s *Service) RemoveMapping(mapping *Mapping) {
 // acquire mappings for natds which the mapping was unaware of before.
 // Optionally takes renew flag which indicates whether or not we should renew
 // mappings with existing natds
-func (s *Service) updateMapping(mapping *Mapping, nats map[string]Device, renew bool) {
+func (s *Service) updateMapping(mapping *Mapping, nats map[string]Device, renew bool, stop chan struct{}) {
 	var added, removed []Address
 
 	renewalTime := time.Duration(s.cfg.Options().NATRenewalM) * time.Minute
 	mapping.expires = time.Now().Add(renewalTime)
 
-	newAdded, newRemoved := s.verifyExistingMappings(mapping, nats, renew)
+	newAdded, newRemoved := s.verifyExistingMappings(mapping, nats, renew, stop)
 	added = append(added, newAdded...)
 	removed = append(removed, newRemoved...)
 
-	newAdded, newRemoved = s.acquireNewMappings(mapping, nats)
+	newAdded, newRemoved = s.acquireNewMappings(mapping, nats, stop)
 	added = append(added, newAdded...)
 	removed = append(removed, newRemoved...)
 
@@ -197,12 +196,18 @@ func (s *Service) updateMapping(mapping *Mapping, nats map[string]Device, renew
 	}
 }
 
-func (s *Service) verifyExistingMappings(mapping *Mapping, nats map[string]Device, renew bool) ([]Address, []Address) {
+func (s *Service) verifyExistingMappings(mapping *Mapping, nats map[string]Device, renew bool, stop chan struct{}) ([]Address, []Address) {
 	var added, removed []Address
 
 	leaseTime := time.Duration(s.cfg.Options().NATLeaseM) * time.Minute
 
 	for id, address := range mapping.addressMap() {
+		select {
+		case <-stop:
+			return nil, nil
+		default:
+		}
+
 		// Delete addresses for NATDevice's that do not exist anymore
 		nat, ok := nats[id]
 		if !ok {
@@ -242,13 +247,19 @@ func (s *Service) verifyExistingMappings(mapping *Mapping, nats map[string]Devic
 	return added, removed
 }
 
-func (s *Service) acquireNewMappings(mapping *Mapping, nats map[string]Device) ([]Address, []Address) {
+func (s *Service) acquireNewMappings(mapping *Mapping, nats map[string]Device, stop chan struct{}) ([]Address, []Address) {
 	var added, removed []Address
 
 	leaseTime := time.Duration(s.cfg.Options().NATLeaseM) * time.Minute
 	addrMap := mapping.addressMap()
 
 	for id, nat := range nats {
+		select {
+		case <-stop:
+			return nil, nil
+		default:
+		}
+
 		if _, ok := addrMap[id]; ok {
 			continue
 		}