kademlia: change pslice mutex to use rwmutex (#313)

pkg/kademlia/kademlia.go

@@ -91,19 +91,24 @@ func New(o Options) *Kad {
 // manage is a forever loop that manages the connection to new peers
 // once they get added or once others leave.
 func (k *Kad) manage() {
-	var peerToRemove swarm.Address
+	var (
+		peerToRemove swarm.Address
+		start        time.Time
+	)
+
 	defer close(k.done)
 	ctx, cancel := context.WithCancel(context.Background())
 	go func() {
 		<-k.quit
 		cancel()
 	}()
-
 	for {
 		select {
 		case <-k.quit:
 			return
 		case <-k.manageC:
+			start = time.Now()
+
 			err := k.knownPeers.EachBinRev(func(peer swarm.Address, po uint8) (bool, bool, error) {
 				if k.connectedPeers.Exists(peer) {
 					return false, false, nil
@@ -166,6 +171,7 @@ func (k *Kad) manage() {
 				// be made before checking the next peer, so we iterate to next
 				return false, false, nil
 			})
+			k.logger.Tracef("kademlia iterator took %s to finish", time.Since(start))
 
 			if err != nil {
 				if errors.Is(err, errMissingAddressBookEntry) {

pkg/kademlia/pslice/pslice.go

@@ -19,7 +19,7 @@ type PSlice struct {
 	peers []swarm.Address // the slice of peers
 	bins  []uint          // the indexes of every proximity order in the peers slice, index is po, value is index of peers slice
 
-	sync.Mutex
+	sync.RWMutex
 }
 
 // New creates a new PSlice.
@@ -32,8 +32,8 @@ func New(maxBins int) *PSlice {
 
 // iterates over all peers from deepest bin to shallowest.
 func (s *PSlice) EachBin(pf topology.EachPeerFunc) error {
-	s.Lock()
-	defer s.Unlock()
+	s.RLock()
+	defer s.RUnlock()
 
 	if len(s.peers) == 0 {
 		return nil
@@ -63,8 +63,8 @@ func (s *PSlice) EachBin(pf topology.EachPeerFunc) error {
 
 // EachBinRev iterates over all peers from shallowest bin to deepest.
 func (s *PSlice) EachBinRev(pf topology.EachPeerFunc) error {
-	s.Lock()
-	defer s.Unlock()
+	s.RLock()
+	defer s.RUnlock()
 
 	if len(s.peers) == 0 {
 		return nil
@@ -96,8 +96,8 @@ func (s *PSlice) EachBinRev(pf topology.EachPeerFunc) error {
 }
 
 func (s *PSlice) Length() int {
-	s.Lock()
-	defer s.Unlock()
+	s.RLock()
+	defer s.RUnlock()
 
 	return len(s.peers)
 }
@@ -105,8 +105,8 @@ func (s *PSlice) Length() int {
 // ShallowestEmpty returns the shallowest empty bin if one exists.
 // If such bin does not exists, returns true as bool value.
 func (s *PSlice) ShallowestEmpty() (bin uint8, none bool) {
-	s.Lock()
-	defer s.Unlock()
+	s.RLock()
+	defer s.RUnlock()
 
 	binCp := make([]uint, len(s.bins)+1)
 	copy(binCp, s.bins)
@@ -122,8 +122,8 @@ func (s *PSlice) ShallowestEmpty() (bin uint8, none bool) {
 
 // Exists checks if a peer exists.
 func (s *PSlice) Exists(addr swarm.Address) bool {
-	s.Lock()
-	defer s.Unlock()
+	s.RLock()
+	defer s.RUnlock()
 
 	b, _ := s.exists(addr)
 	return b