ks-291: minor peer discovery optimization

core/services/p2p/counter.go

@@ -0,0 +1,23 @@
+package p2p
+
+import (
+	"encoding/binary"
+)
+
+// counter is a simple abstraction that can be used to generate unique peer group IDs.
+type counter struct {
+	x uint64
+}
+
+// Bytes returns the counter as a 32-byte array.
+func (g *counter) Bytes() [32]byte {
+	var b [32]byte
+	binary.BigEndian.PutUint64(b[24:], g.x)
+	return b
+}
+
+// Inc increments the counter.
+func (g *counter) Inc() *counter {
+	g.x++
+	return g
+}

core/services/p2p/counter_test.go

@@ -0,0 +1,16 @@
+package p2p
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_groupID(t *testing.T) {
+	g := &counter{}
+	assert.Equal(t, [32]byte{}, g.Bytes())
+	g.Inc()
+	assert.Equal(t, [32]byte{31: 1}, g.Bytes())
+	g.Inc()
+	assert.Equal(t, [32]byte{31: 2}, g.Bytes())
+}

core/services/p2p/peer.go

@@ -20,7 +20,6 @@ import (
 )
 
 var (
-	defaultGroupID    = [32]byte{0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01}
 	defaultStreamName = "stream"
 	defaultRecvChSize = 10000
 )
@@ -49,9 +48,10 @@ type peer struct {
 	myID        ragetypes.PeerID
 	recvCh      chan p2ptypes.Message
 
-	stopCh services.StopChan
-	wg     sync.WaitGroup
-	lggr   logger.Logger
+	stopCh  services.StopChan
+	wg      sync.WaitGroup
+	lggr    logger.Logger
+	groupID *counter
 }
 
 var _ p2ptypes.Peer = &peer{}
@@ -99,6 +99,7 @@ func NewPeer(cfg PeerConfig, lggr logger.Logger) (*peer, error) {
 		recvCh:      make(chan p2ptypes.Message, defaultRecvChSize),
 		stopCh:      make(services.StopChan),
 		lggr:        lggr.Named("P2PPeer"),
+		groupID:     &counter{},
 	}, nil
 }
 
@@ -113,18 +114,21 @@ func (p *peer) UpdateConnections(peers map[ragetypes.PeerID]p2ptypes.StreamConfi
 			return err
 		}
 	}
-
-	if err := p.discoverer.RemoveGroup(defaultGroupID); err != nil {
-		p.lggr.Warnw("failed to remove old group", "groupID", defaultGroupID)
-	}
+	// updating the group is a small optimization that avoids reconnecting to existing peers
+	currentGroupID := p.groupID.Bytes()
+	newGroupID := p.groupID.Inc().Bytes()
 	peerIDs := []ragetypes.PeerID{}
 	for pid := range peers {
 		peerIDs = append(peerIDs, pid)
 	}
-	if err := p.discoverer.AddGroup(defaultGroupID, peerIDs, p.cfg.Bootstrappers); err != nil {
-		p.lggr.Warnw("failed to add group", "groupID", defaultGroupID)
+	if err := p.discoverer.AddGroup(newGroupID, peerIDs, p.cfg.Bootstrappers); err != nil {
+		p.lggr.Warnw("failed to add group", "groupID", newGroupID)
 		return err
 	}
+	if err := p.discoverer.RemoveGroup(currentGroupID); err != nil {
+		p.lggr.Warnw("failed to remove old group", "groupID", currentGroupID)
+	}
+
 	return nil
 }