replaced topic lock by atomic boolean to avoid lock contention

Author: aratz-lasa

.vscode/dryrun.log

@@ -0,0 +1,6 @@
+make --dry-run --always-make --keep-going --print-directory
+make: Entering directory '/home/aratz/github.com/aratz-lasa/go-libp2p-pubsub'
+make: Leaving directory '/home/aratz/github.com/aratz-lasa/go-libp2p-pubsub'
+ 
+make: *** No targets specified and no makefile found.  Stop.
+

go.mod

@@ -13,4 +13,5 @@ require (
 	github.com/libp2p/go-msgio v0.2.0
 	github.com/multiformats/go-multiaddr v0.5.0
 	github.com/whyrusleeping/timecache v0.0.0-20160911033111-cfcb2f1abfee
+	go.uber.org/atomic v1.7.0
 )

topic.go

@@ -11,6 +11,7 @@ import (
 	pb "github.com/libp2p/go-libp2p-pubsub/pb"
 
 	"github.com/libp2p/go-libp2p-core/peer"
+	"go.uber.org/atomic"
 )
 
 // ErrTopicClosed is returned if a Topic is utilized after it has been closed
@@ -30,8 +31,7 @@ type Topic struct {
 	evtHandlerMux sync.RWMutex
 	evtHandlers   map[*TopicEventHandler]struct{}
 
-	mux    sync.RWMutex
-	closed bool
+	closed atomic.Bool
 }
 
 // String returns the topic associated with t
@@ -47,10 +47,7 @@ func (t *Topic) SetScoreParams(p *TopicScoreParams) error {
 		return fmt.Errorf("invalid topic score parameters: %w", err)
 	}
 
-	t.mux.Lock()
-	defer t.mux.Unlock()
-
-	if t.closed {
+	if t.closed.Load() {
 		return ErrTopicClosed
 	}
 
@@ -84,9 +81,7 @@ func (t *Topic) SetScoreParams(p *TopicScoreParams) error {
 // EventHandler creates a handle for topic specific events
 // Multiple event handlers may be created and will operate independently of each other
 func (t *Topic) EventHandler(opts ...TopicEventHandlerOpt) (*TopicEventHandler, error) {
-	t.mux.RLock()
-	defer t.mux.RUnlock()
-	if t.closed {
+	if t.closed.Load() {
 		return nil, ErrTopicClosed
 	}
 
@@ -141,9 +136,7 @@ func (t *Topic) sendNotification(evt PeerEvent) {
 // Note that subscription is not an instantaneous operation. It may take some time
 // before the subscription is processed by the pubsub main loop and propagated to our peers.
 func (t *Topic) Subscribe(opts ...SubOpt) (*Subscription, error) {
-	t.mux.RLock()
-	defer t.mux.RUnlock()
-	if t.closed {
+	if t.closed.Load() {
 		return nil, ErrTopicClosed
 	}
 
@@ -184,9 +177,7 @@ func (t *Topic) Subscribe(opts ...SubOpt) (*Subscription, error) {
 // cancel function. Subsequent calls increase the reference counter.
 // To completely disable the relay, all references must be cancelled.
 func (t *Topic) Relay() (RelayCancelFunc, error) {
-	t.mux.RLock()
-	defer t.mux.RUnlock()
-	if t.closed {
+	if t.closed.Load() {
 		return nil, ErrTopicClosed
 	}
 
@@ -215,16 +206,14 @@ type ProvideKey func() (crypto.PrivKey, peer.ID)
 type PublishOptions struct {
 	ready     RouterReady
 	customKey ProvideKey
-	local bool
+	local     bool
 }
 
 type PubOpt func(pub *PublishOptions) error
 
 // Publish publishes data to topic.
 func (t *Topic) Publish(ctx context.Context, data []byte, opts ...PubOpt) error {
-	t.mux.RLock()
-	defer t.mux.RUnlock()
-	if t.closed {
+	if t.closed.Load() {
 		return ErrTopicClosed
 	}
 
@@ -347,9 +336,7 @@ func WithSecretKeyAndPeerId(key crypto.PrivKey, pid peer.ID) PubOpt {
 // Close closes down the topic. Will return an error unless there are no active event handlers or subscriptions.
 // Does not error if the topic is already closed.
 func (t *Topic) Close() error {
-	t.mux.Lock()
-	defer t.mux.Unlock()
-	if t.closed {
+	if t.closed.Load() {
 		return nil
 	}
 
@@ -364,17 +351,15 @@ func (t *Topic) Close() error {
 	err := <-req.resp
 
 	if err == nil {
-		t.closed = true
+		t.closed.Swap(true)
 	}
 
 	return err
 }
 
 // ListPeers returns a list of peers we are connected to in the given topic.
 func (t *Topic) ListPeers() []peer.ID {
-	t.mux.RLock()
-	defer t.mux.RUnlock()
-	if t.closed {
+	if t.closed.Load() {
 		return []peer.ID{}
 	}