Remove unguarded and unread peers field

pkg/beacon/beacon.go

@@ -188,7 +188,6 @@ type node struct {
 	lastEventTimeMu sync.RWMutex
 	nodeVersion     string
 	nodeVersionMu   sync.RWMutex
-	peers           types.Peers
 	finality        *v1.Finality
 	spec            *state.Spec
 	specMu          sync.RWMutex

pkg/beacon/fetch.go

@@ -38,8 +38,6 @@ func (n *node) FetchPeers(ctx context.Context) (*types.Peers, error) {
 		return nil, err
 	}
 
-	n.peers = peers
-
 	n.publishPeersUpdated(ctx, peers)
 
 	return &peers, nil

pkg/beacon/fetch_test.go

@@ -0,0 +1,68 @@
+package beacon
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	"github.com/chuckpreslar/emission"
+	"github.com/ethpandaops/beacon/pkg/beacon/api/types"
+	"github.com/sirupsen/logrus"
+)
+
+type peersFakeAPI struct{}
+
+func (f *peersFakeAPI) NodePeer(context.Context, string) (types.Peer, error) {
+	return types.Peer{}, nil
+}
+
+func (f *peersFakeAPI) NodePeers(context.Context) (types.Peers, error) {
+	return types.Peers{{PeerID: "a"}, {PeerID: "b"}}, nil
+}
+
+func (f *peersFakeAPI) NodePeerCount(context.Context) (types.PeerCount, error) {
+	return types.PeerCount{}, nil
+}
+
+func (f *peersFakeAPI) RawBlock(context.Context, string, string) ([]byte, error) { return nil, nil }
+
+func (f *peersFakeAPI) RawDebugBeaconState(context.Context, string, string) ([]byte, error) {
+	return nil, nil
+}
+
+func (f *peersFakeAPI) DepositSnapshot(context.Context) (*types.DepositSnapshot, error) {
+	return nil, nil
+}
+
+func (f *peersFakeAPI) NodeIdentity(context.Context) (*types.Identity, error) { return nil, nil }
+
+// TestFetchPeersConcurrent exercises concurrent FetchPeers calls, the shape
+// of the 60s peers cron running alongside a consumer calling FetchPeers
+// directly. Should be clean under -race now that FetchPeers no longer
+// writes to a shared, unguarded field.
+func TestFetchPeersConcurrent(t *testing.T) {
+	log := logrus.New()
+	log.SetLevel(logrus.PanicLevel)
+
+	n := &node{
+		log:    log,
+		broker: emission.NewEmitter(),
+		api:    &peersFakeAPI{},
+	}
+
+	ctx := context.Background()
+
+	var wg sync.WaitGroup
+
+	for range 8 {
+		wg.Go(func() {
+			for range 50 {
+				if _, err := n.FetchPeers(ctx); err != nil {
+					t.Error(err)
+				}
+			}
+		})
+	}
+
+	wg.Wait()
+}