p2p: add libp2p feature flag (#8410)

config/config.go

@@ -674,6 +674,11 @@ type P2PConfig struct { //nolint: maligned
 	// layer uses. Options are: "fifo" and "priority",
 	// with the default being "priority".
 	QueueType string `mapstructure:"queue-type"`
+
+	// UseLibP2P switches to using the new networking layer based
+	// on libp2p. This option is unlikely to persist into a
+	// release of tendermint, but will ease the transition.
+	UseLibP2P bool `mapstructure:"experimental-use-lib-p2p"`
 }
 
 // DefaultP2PConfig returns a default configuration for the peer-to-peer layer

internal/p2p/router.go

@@ -72,6 +72,10 @@ type RouterOptions struct {
 	// are used to dial peers. This defaults to the value of
 	// runtime.NumCPU.
 	NumConcurrentDials func() int
+
+	// UseLibP2P toggles the use of the new networking layer
+	// within the router.
+	UseLibP2P bool
 }
 
 const (
@@ -191,6 +195,10 @@ func NewRouter(
 		return nil, err
 	}
 
+	if options.UseLibP2P {
+		return nil, errors.New("libp2p is not supported")
+	}
+
 	router := &Router{
 		logger:           logger,
 		metrics:          metrics,

internal/p2p/router_test.go

@@ -26,6 +26,34 @@ import (
 	"github.com/tendermint/tendermint/types"
 )
 
+func TestRouterConstruction(t *testing.T) {
+	opts := p2p.RouterOptions{UseLibP2P: true}
+	if err := opts.Validate(); err != nil {
+		t.Fatalf("options should validate: %v", err)
+	}
+	logger := log.NewNopLogger()
+	metrics := p2p.NopMetrics()
+
+	router, err := p2p.NewRouter(
+		logger,
+		metrics,
+		nil, // privkey
+		nil, // peermanager
+		func() *types.NodeInfo { return &types.NodeInfo{} },
+		[]p2p.Transport{},
+		[]p2p.Endpoint{},
+		opts,
+	)
+	if err == nil {
+		t.Error("support for libp2p does not exist, and should prevent the router from being constructed")
+	} else if err.Error() != "libp2p is not supported" {
+		t.Errorf("incorrect error: %q", err.Error())
+	}
+	if router != nil {
+		t.Error("router was constructed when it should not have been")
+	}
+}
+
 func echoReactor(ctx context.Context, channel *p2p.Channel) {
 	iter := channel.Receive(ctx)
 	for iter.Next(ctx) {

node/node.go

@@ -716,6 +716,7 @@ func loadStateFromDBOrGenesisDocProvider(stateStore sm.Store, genDoc *types.Gene
 func getRouterConfig(conf *config.Config, appClient abciclient.Client) p2p.RouterOptions {
 	opts := p2p.RouterOptions{
 		QueueType: conf.P2P.QueueType,
+		UseLibP2P: conf.P2P.UseLibP2P,
 	}
 
 	if conf.FilterPeers && appClient != nil {