p2p: Allow to config bucket size of DHT

Currently, the bucket size of the DHT is hardcoded to 16. This commit introduces a new flag --dht.bucketsize, allowing users to configure the bucket size as needed.

cmd/ronin/main.go

@@ -180,6 +180,7 @@ var (
 		utils.DisableRoninProtocol,
 		utils.AdditionalChainEventFlag,
 		utils.DBEngineFlag,
+		utils.DHTBucketSizeFlag,
 	}
 
 	rpcFlags = []cli.Flag{

cmd/utils/flags.go

@@ -871,6 +871,12 @@ var (
 		Usage:    "Sets DNS discovery entry points (use \"\" to disable DNS)",
 		Category: flags.NetworkingCategory,
 	}
+	DHTBucketSizeFlag = &cli.IntFlag{
+		Name:     "dht.bucketsize",
+		Usage:    "Size of each DHT bucket",
+		Value:    16,
+		Category: flags.NetworkingCategory,
+	}
 
 	// ATM the url is left to the user and deployment to
 	JSpathFlag = &flags.DirectoryFlag{
@@ -1542,6 +1548,7 @@ func SetP2PConfig(ctx *cli.Context, cfg *p2p.Config) {
 		cfg.NoDiscovery = true
 		cfg.DiscoveryV5 = false
 	}
+	cfg.DHTBucketSize = ctx.Int(DHTBucketSizeFlag.Name)
 }
 
 // SetNodeConfig applies node-related command line flags to the config.

eth/ethconfig/config.go

@@ -228,6 +228,9 @@ type Config struct {
 
 	// Send additional chain event
 	EnableAdditionalChainEvent bool
+
+	// Size of each bucket in DHT
+	DHTBucketSize int
 }
 
 // CreateConsensusEngine creates a consensus engine for the given chain configuration.

p2p/discover/common.go

@@ -78,6 +78,7 @@ type Config struct {
 	ValidSchemes   enr.IdentityScheme // allowed identity schemes
 	Clock          mclock.Clock
 	FilterFunction NodeFilterFunc // function for filtering ENR entries
+	DHTBucketSize  int            // size of each bucket in DHT
 }
 
 func (cfg Config) withDefaults() Config {

p2p/discover/lookup.go

@@ -73,7 +73,7 @@ func (it *lookup) advance() bool {
 			for _, n := range nodes {
 				if n != nil && !it.seen[n.ID()] {
 					it.seen[n.ID()] = true
-					it.result.push(n, bucketSize)
+					it.result.push(n, defaultBucketSize)
 					it.replyBuffer = append(it.replyBuffer, n)
 				}
 			}
@@ -104,7 +104,7 @@ func (it *lookup) startQueries() bool {
 
 	// The first query returns nodes from the local table.
 	if it.queries == -1 {
-		closest := it.tab.findnodeByID(it.result.target, bucketSize, false)
+		closest := it.tab.findnodeByID(it.result.target, defaultBucketSize, false)
 		// Avoid finishing the lookup too quickly if table is empty. It'd be better to wait
 		// for the table to fill in this case, but there is no good mechanism for that
 		// yet.
@@ -151,7 +151,7 @@ func (it *lookup) query(n *node, reply chan<- []*node) {
 		// Remove the node from the local table if it fails to return anything useful too
 		// many times, but only if there are enough other nodes in the bucket.
 		dropped := false
-		if fails >= maxFindnodeFailures && it.tab.bucketLen(n.ID()) >= bucketSize/2 {
+		if fails >= maxFindnodeFailures && it.tab.bucketLen(n.ID()) >= defaultBucketSize/2 {
 			dropped = true
 			it.tab.delete(n)
 		}

p2p/discover/table.go

@@ -41,7 +41,7 @@ import (
 
 const (
 	alpha                  = 3               // Kademlia concurrency factor
-	bucketSize             = 16              // Kademlia bucket size
+	defaultBucketSize      = 16              // Kademlia bucket size
 	maxReplacements        = 10              // Size of per-bucket replacement list
 	maxWorkerTask          = 90              // Maximum number of worker tasks
 	timeoutWorkerTaskClose = 1 * time.Second // Timeout for waiting workerPoolTask is refill full
@@ -67,11 +67,12 @@ const (
 // itself up-to-date by verifying the liveness of neighbors and requesting their node
 // records when announcements of a new record version are received.
 type Table struct {
-	mutex   sync.Mutex        // protects buckets, bucket content, nursery, rand
-	buckets [nBuckets]*bucket // index of known nodes by distance
-	nursery []*node           // bootstrap nodes
-	rand    *mrand.Rand       // source of randomness, periodically reseeded
-	ips     netutil.DistinctNetSet
+	mutex      sync.Mutex        // protects buckets, bucket content, nursery, rand
+	buckets    [nBuckets]*bucket // index of known nodes by distance
+	nursery    []*node           // bootstrap nodes
+	rand       *mrand.Rand       // source of randomness, periodically reseeded
+	ips        netutil.DistinctNetSet
+	bucketSize int
 
 	log            log.Logger
 	db             *enode.DB // database of known nodes
@@ -105,7 +106,7 @@ type bucket struct {
 	index        int
 }
 
-func newTable(t transport, db *enode.DB, bootnodes []*enode.Node, log log.Logger, filter NodeFilterFunc) (*Table, error) {
+func newTable(t transport, db *enode.DB, bootnodes []*enode.Node, log log.Logger, filter NodeFilterFunc, bucketSize int) (*Table, error) {
 	tab := &Table{
 		net:            t,
 		db:             db,
@@ -118,6 +119,7 @@ func newTable(t transport, db *enode.DB, bootnodes []*enode.Node, log log.Logger
 		ips:            netutil.DistinctNetSet{Subnet: tableSubnet, Limit: tableIPLimit},
 		log:            log,
 		enrFilter:      filter,
+		bucketSize:     bucketSize,
 	}
 	if err := tab.setFallbackNodes(bootnodes); err != nil {
 		return nil, err
@@ -131,15 +133,19 @@ func newTable(t transport, db *enode.DB, bootnodes []*enode.Node, log log.Logger
 	for i := 0; i < maxWorkerTask; i++ {
 		tab.workerPoolTask <- struct{}{}
 	}
+	// Set default bucket size if bucketSize is not set
+	if tab.bucketSize <= 0 {
+		tab.bucketSize = defaultBucketSize
+	}
 
 	tab.seedRand()
 	tab.loadSeedNodes()
 
 	return tab, nil
 }
 
-func newMeteredTable(t transport, db *enode.DB, bootnodes []*enode.Node, log log.Logger, filter NodeFilterFunc) (*Table, error) {
-	tab, err := newTable(t, db, bootnodes, log, filter)
+func newMeteredTable(t transport, db *enode.DB, bootnodes []*enode.Node, log log.Logger, filter NodeFilterFunc, bucketSize int) (*Table, error) {
+	tab, err := newTable(t, db, bootnodes, log, filter, bucketSize)
 	if err != nil {
 		return nil, err
 	}
@@ -557,7 +563,7 @@ func (tab *Table) addSeenNodeSync(n *node) {
 		// Already in bucket, don't add.
 		return
 	}
-	if len(b.entries) >= bucketSize {
+	if len(b.entries) >= tab.bucketSize {
 		// Bucket full, maybe add as replacement.
 		tab.addReplacement(b, n)
 		return
@@ -636,7 +642,7 @@ func (tab *Table) addVerifiedNodeSync(n *node) {
 		// Already in bucket, moved to front.
 		return
 	}
-	if len(b.entries) >= bucketSize {
+	if len(b.entries) >= tab.bucketSize {
 		// Bucket full, maybe add as replacement.
 		tab.addReplacement(b, n)
 		return
@@ -646,7 +652,7 @@ func (tab *Table) addVerifiedNodeSync(n *node) {
 		return
 	}
 	// Add to front of bucket.
-	b.entries, _ = pushNode(b.entries, n, bucketSize)
+	b.entries, _ = pushNode(b.entries, n, tab.bucketSize)
 	b.replacements = deleteNode(b.replacements, n)
 	n.addedAt = time.Now()
 	if tab.nodeAddedHook != nil {

p2p/discover/table_test.go

@@ -79,7 +79,7 @@ func testPingReplace(t *testing.T, newNodeIsResponding, lastInBucketIsResponding
 
 	tab.mutex.Lock()
 	defer tab.mutex.Unlock()
-	wantSize := bucketSize
+	wantSize := defaultBucketSize
 	if !lastInBucketIsResponding && !newNodeIsResponding {
 		wantSize--
 	}
@@ -102,7 +102,7 @@ func TestBucket_bumpNoDuplicates(t *testing.T) {
 		Rand:     rand.New(rand.NewSource(time.Now().Unix())),
 		Values: func(args []reflect.Value, rand *rand.Rand) {
 			// generate a random list of nodes. this will be the content of the bucket.
-			n := rand.Intn(bucketSize-1) + 1
+			n := rand.Intn(defaultBucketSize-1) + 1
 			nodes := make([]*node, n)
 			for i := range nodes {
 				nodes[i] = nodeAtDistance(enode.ID{}, 200, intIP(200))
@@ -296,7 +296,7 @@ func (*closeTest) Generate(rand *rand.Rand, size int) reflect.Value {
 	t := &closeTest{
 		Self:   gen(enode.ID{}, rand).(enode.ID),
 		Target: gen(enode.ID{}, rand).(enode.ID),
-		N:      rand.Intn(bucketSize),
+		N:      rand.Intn(defaultBucketSize),
 	}
 	for _, id := range gen([]enode.ID{}, rand).([]enode.ID) {
 		r := new(enr.Record)

p2p/discover/table_util_test.go

@@ -43,7 +43,7 @@ func init() {
 
 func newTestTable(t transport) (*Table, *enode.DB) {
 	db, _ := enode.OpenDB("")
-	tab, _ := newTable(t, db, nil, log.Root(), nil)
+	tab, _ := newTable(t, db, nil, log.Root(), nil, defaultBucketSize)
 	go tab.loop()
 	return tab, db
 }
@@ -100,10 +100,10 @@ func intIP(i int) net.IP {
 func fillBucket(tab *Table, n *node) (last *node) {
 	ld := enode.LogDist(tab.self().ID(), n.ID())
 	b := tab.bucket(n.ID())
-	for len(b.entries) < bucketSize {
+	for len(b.entries) < tab.bucketSize {
 		b.entries = append(b.entries, nodeAtDistance(tab.self().ID(), ld, intIP(ld)))
 	}
-	return b.entries[bucketSize-1]
+	return b.entries[tab.bucketSize-1]
 }
 
 // fillTable adds nodes the table to the end of their corresponding bucket

p2p/discover/v4_lookup_test.go

@@ -58,8 +58,8 @@ func TestUDPv4_Lookup(t *testing.T) {
 	for _, e := range results {
 		t.Logf("  ld=%d, %x", enode.LogDist(lookupTestnet.target.id(), e.ID()), e.ID().Bytes())
 	}
-	if len(results) != bucketSize {
-		t.Errorf("wrong number of results: got %d, want %d", len(results), bucketSize)
+	if len(results) != defaultBucketSize {
+		t.Errorf("wrong number of results: got %d, want %d", len(results), defaultBucketSize)
 	}
 	checkLookupResults(t, lookupTestnet, results)
 }

p2p/discover/v4_udp.go

@@ -142,7 +142,7 @@ func ListenV4(c UDPConn, ln *enode.LocalNode, cfg Config) (*UDPv4, error) {
 		log:             cfg.Log,
 	}
 
-	tab, err := newMeteredTable(t, ln.Database(), cfg.Bootnodes, t.log, cfg.FilterFunction)
+	tab, err := newMeteredTable(t, ln.Database(), cfg.Bootnodes, t.log, cfg.FilterFunction, cfg.DHTBucketSize)
 	if err != nil {
 		return nil, err
 	}
@@ -303,7 +303,7 @@ func (t *UDPv4) findnode(toid enode.ID, toaddr *net.UDPAddr, target v4wire.Pubke
 
 	// Add a matcher for 'neighbours' replies to the pending reply queue. The matcher is
 	// active until enough nodes have been received.
-	nodes := make([]*node, 0, bucketSize)
+	nodes := make([]*node, 0, defaultBucketSize)
 	nreceived := 0
 	rm := t.pending(toid, toaddr.IP, v4wire.NeighborsPacket, func(r v4wire.Packet) (matched bool, requestDone bool) {
 		reply := r.(*v4wire.Neighbors)
@@ -316,7 +316,7 @@ func (t *UDPv4) findnode(toid enode.ID, toaddr *net.UDPAddr, target v4wire.Pubke
 			}
 			nodes = append(nodes, n)
 		}
-		return true, nreceived >= bucketSize
+		return true, nreceived >= defaultBucketSize
 	})
 	t.send(toaddr, toid, &v4wire.Findnode{
 		Target:     target,
@@ -721,7 +721,7 @@ func (t *UDPv4) handleFindnode(h *packetHandlerV4, from *net.UDPAddr, fromID eno
 
 	// Determine closest nodes.
 	target := enode.ID(crypto.Keccak256Hash(req.Target[:]))
-	closest := t.tab.findnodeByID(target, bucketSize, true).entries
+	closest := t.tab.findnodeByID(target, defaultBucketSize, true).entries
 
 	// Send neighbors in chunks with at most maxNeighbors per packet
 	// to stay below the packet size limit.

p2p/discover/v4_udp_test.go

@@ -258,7 +258,7 @@ func TestUDPv4_findnode(t *testing.T) {
 	// take care not to overflow any bucket.
 	nodes := &nodesByDistance{target: testTarget.ID()}
 	live := make(map[enode.ID]bool)
-	numCandidates := 2 * bucketSize
+	numCandidates := 2 * defaultBucketSize
 	for i := 0; i < numCandidates; i++ {
 		key := newkey()
 		ip := net.IP{10, 13, 0, byte(i)}
@@ -278,12 +278,12 @@ func TestUDPv4_findnode(t *testing.T) {
 	test.table.db.UpdateLastPongReceived(remoteID, test.remoteaddr.IP, time.Now())
 
 	// check that closest neighbors are returned.
-	expected := test.table.findnodeByID(testTarget.ID(), bucketSize, true)
+	expected := test.table.findnodeByID(testTarget.ID(), defaultBucketSize, true)
 	test.packetIn(nil, &v4wire.Findnode{Target: testTarget, Expiration: futureExp})
 	waitNeighbors := func(want []*node) {
 		test.waitPacketOut(func(p *v4wire.Neighbors, to *net.UDPAddr, hash []byte) {
 			if len(p.Nodes) != len(want) {
-				t.Errorf("wrong number of results: got %d, want %d", len(p.Nodes), bucketSize)
+				t.Errorf("wrong number of results: got %d, want %d", len(p.Nodes), defaultBucketSize)
 			}
 			for i, n := range p.Nodes {
 				if n.ID.ID() != want[i].ID() {

p2p/discover/v5_udp.go

@@ -164,7 +164,7 @@ func newUDPv5(conn UDPConn, ln *enode.LocalNode, cfg Config) (*UDPv5, error) {
 		closeCtx:       closeCtx,
 		cancelCloseCtx: cancelCloseCtx,
 	}
-	tab, err := newMeteredTable(t, t.db, cfg.Bootnodes, cfg.Log, cfg.FilterFunction)
+	tab, err := newMeteredTable(t, t.db, cfg.Bootnodes, cfg.Log, cfg.FilterFunction, cfg.DHTBucketSize)
 	if err != nil {
 		return nil, err
 	}

p2p/server.go

@@ -168,6 +168,9 @@ type Config struct {
 	Logger log.Logger `toml:",omitempty"`
 
 	clock mclock.Clock
+
+	// Size of each bucket in DHT
+	DHTBucketSize int
 }
 
 // Server manages all peer connections.
@@ -630,6 +633,7 @@ func (srv *Server) setupDiscovery() error {
 			Unhandled:      unhandled,
 			Log:            srv.log,
 			FilterFunction: f,
+			DHTBucketSize:  srv.Config.DHTBucketSize,
 		}
 		ntab, err := discover.ListenV4(conn, srv.localnode, cfg)
 		if err != nil {