Explicitly disable discovery (#886)

* Make it possible to explicitly disable discovery

Discovery will be disabled in following cases:
- if there are not bootnodes - v5 server will be disabled
because there is no point in running it
- if user defined in config NoDiscovery=true this value will be preserved
even if we have bootnodes

So, basically discovery will be always enabled by default on mobile, unless
it is explicitly specified otherwise.

When statusd is used current behavior is that discovery is disabled by default.
I kept it in this change, but it would be better to change it.

* Fix leftovers

* Add wait group to peer pool to protect from races with p2p.Server

* Change fields only when all goroutines finished

* Turn off discovery after topic searches are stopped

* Don't set period to nil to avoid race with SearchTopic

* Close period chan only when all writers are finished

cmd/statusd/main.go

@@ -261,7 +261,7 @@ func makeNodeConfig() (*params.NodeConfig, error) {
 		nodeConfig.ClusterConfig.BootNodes = nil
 	}
 
-	nodeConfig.Discovery = *discovery
+	nodeConfig.NoDiscovery = !(*discovery)
 	nodeConfig.RequireTopics = map[discv5.Topic]params.Limits(searchTopics)
 	nodeConfig.RegisterTopics = []discv5.Topic(registerTopics)
 

geth/node/node.go

@@ -114,8 +114,8 @@ func defaultEmbeddedNodeConfig(config *params.NodeConfig) *node.Config {
 		Name:              config.Name,
 		Version:           config.Version,
 		P2P: p2p.Config{
-			NoDiscovery:     true,
-			DiscoveryV5:     config.Discovery,
+			NoDiscovery:     true, // we always use only v5 server
+			DiscoveryV5:     !config.NoDiscovery,
 			ListenAddr:      config.ListenAddr,
 			NAT:             nat.Any(),
 			MaxPeers:        config.MaxPeers,

geth/node/status_node.go

@@ -110,11 +110,10 @@ func (n *StatusNode) Start(config *params.NodeConfig, services ...node.ServiceCo
 	if err := n.setupDeduplicator(); err != nil {
 		return err
 	}
-
-	if n.config.Discovery {
-		return n.startPeerPool()
-	}
+	if n.config.NoDiscovery {
 		return nil
+	}
+	return n.startPeerPool()
 }
 
 func (n *StatusNode) setupDeduplicator() error {
@@ -224,7 +223,7 @@ func (n *StatusNode) stop() error {
 }
 
 func (n *StatusNode) stopPeerPool() error {
-	if !n.config.Discovery {
+	if n.config.NoDiscovery {
 		return nil
 	}
 

geth/params/cluster.go

@@ -2,7 +2,6 @@ package params
 
 type cluster struct {
 	NetworkID   int      `json:"networkID"`
-	Discovery   bool     `json:"discovery"`
 	StaticNodes []string `json:"staticnodes"`
 	BootNodes   []string `json:"bootnodes"`
 }
@@ -17,7 +16,6 @@ var ropstenCluster = cluster{
 
 var rinkebyCluster = cluster{
 	NetworkID: 4,
-	Discovery: true,
 	BootNodes: []string{
 		"enode://1b843c7697f6fc42a1f606fb3cfaac54e025f06789dc20ad9278be3388967cf21e3a1b1e4be51faecd66c2c3adef12e942b4fcdeb8727657abe60636efb6224f@206.189.6.46:30404",
 		"enode://b29100c8468e3e6604817174a15e4d71627458b0dcdbeea169ab2eb4ab2bbc6f24adbb175826726cec69db8fdba6c0dd60b3da598e530ede562180d300728659@206.189.6.48:30404",

geth/params/config.go

@@ -228,8 +228,8 @@ type NodeConfig struct {
 	// remote peer identification as well as network traffic encryption.
 	NodeKeyFile string
 
-	// Discovery set to true will enabled discovery protocol.
-	Discovery bool
+	// NoDiscovery set to true will disable discovery protocol.
+	NoDiscovery bool
 
 	// ListenAddr is an IP address and port of this node (e.g. 127.0.0.1:30303).
 	ListenAddr string
@@ -576,9 +576,13 @@ func (c *NodeConfig) updateClusterConfig() error {
 
 	for _, cluster := range clusters {
 		if cluster.NetworkID == int(c.NetworkID) {
-			c.Discovery = cluster.Discovery
 			c.ClusterConfig.BootNodes = cluster.BootNodes
 			c.ClusterConfig.StaticNodes = cluster.StaticNodes
+			// no point in running discovery if we don't have bootnodes.
+			// but in case if we do have nodes and NoDiscovery=true we will preserve that value
+			if len(cluster.BootNodes) == 0 {
+				c.NoDiscovery = true
+			}
 			break
 		}
 	}
@@ -608,7 +612,7 @@ func (c *NodeConfig) updateRelativeDirsConfig() error {
 
 // updatePeerLimits will set default peer limits expectations based on enabled services.
 func (c *NodeConfig) updatePeerLimits() {
-	if !c.Discovery {
+	if c.NoDiscovery {
 		return
 	}
 	if c.WhisperConfig.Enabled {

geth/params/config_test.go

@@ -302,7 +302,7 @@ var loadConfigTestCases = []struct {
 		func(t *testing.T, dataDir string, nodeConfig *params.NodeConfig, err error) {
 			require.NoError(t, err)
 			require.True(t, nodeConfig.ClusterConfig.Enabled, "cluster configuration is expected to be enabled by default")
-			require.True(t, nodeConfig.Discovery)
+			require.False(t, nodeConfig.NoDiscovery)
 			require.True(t, len(nodeConfig.ClusterConfig.BootNodes) >= 2)
 		},
 	},
@@ -343,11 +343,23 @@ var loadConfigTestCases = []struct {
 		func(t *testing.T, dataDir string, nodeConfig *params.NodeConfig, err error) {
 			require.NoError(t, err)
 			require.NotNil(t, nodeConfig.RequireTopics)
-			require.True(t, nodeConfig.Discovery)
+			require.False(t, nodeConfig.NoDiscovery)
 			require.Contains(t, nodeConfig.RequireTopics, params.WhisperDiscv5Topic)
 			require.Equal(t, params.WhisperDiscv5Limits, nodeConfig.RequireTopics[params.WhisperDiscv5Topic])
 		},
 	},
+	{
+		`no discovery preserved`,
+		`{
+			"NetworkId": 4,
+			"DataDir": "$TMPDIR",
+			"NoDiscovery": true
+		}`,
+		func(t *testing.T, dataDir string, nodeConfig *params.NodeConfig, err error) {
+			require.NoError(t, err)
+			require.True(t, nodeConfig.NoDiscovery)
+		},
+	},
 }
 
 // TestLoadNodeConfig tests loading JSON configuration and setting default values.

geth/peers/peerpool.go

@@ -75,6 +75,7 @@ type PeerPool struct {
 	serverSubscription event.Subscription
 	events             chan *p2p.PeerEvent
 	quit               chan struct{}
+	wg                 sync.WaitGroup
 	timeout            <-chan time.Time
 }
 
@@ -100,8 +101,10 @@ func (p *PeerPool) Start(server *p2p.Server) error {
 
 	p.events = make(chan *p2p.PeerEvent, 20)
 	p.serverSubscription = server.SubscribeEvents(p.events)
+	p.wg.Add(1)
 	go func() {
 		p.handleServerPeers(server, p.events)
+		p.wg.Done()
 	}()
 	return nil
 }
@@ -130,16 +133,16 @@ func (p *PeerPool) stopDiscovery(server *p2p.Server) {
 		return
 	}
 
+	for _, t := range p.topics {
+		t.StopSearch()
+	}
+
 	p.mu.Lock()
 	server.DiscV5.Close()
 	server.DiscV5 = nil
 	p.timeout = nil
 	p.mu.Unlock()
 
-	for _, t := range p.topics {
-		t.StopSearch()
-	}
-
 	signal.SendDiscoveryStopped()
 }
 
@@ -262,4 +265,5 @@ func (p *PeerPool) Stop() {
 		close(p.quit)
 	}
 	p.serverSubscription.Unsubscribe()
+	p.wg.Wait()
 }

geth/peers/topicpool.go

@@ -42,7 +42,8 @@ type TopicPool struct {
 	fastModeTimeout time.Duration
 
 	mu     sync.RWMutex
-	wg   sync.WaitGroup // wait group for all goroutines spawn during TopicPool operation
+	discWG sync.WaitGroup
+	poolWG sync.WaitGroup
 	quit   chan struct{}
 
 	running int32
@@ -159,9 +160,9 @@ func (t *TopicPool) limitFastMode(timeout time.Duration) chan struct{} {
 
 	cancel := make(chan struct{})
 
-	t.wg.Add(1)
+	t.poolWG.Add(1)
 	go func() {
-		defer t.wg.Done()
+		defer t.poolWG.Done()
 
 		select {
 		case <-time.After(timeout):
@@ -318,15 +319,15 @@ func (t *TopicPool) StartSearch(server *p2p.Server) error {
 		}
 	}
 
-	t.wg.Add(1)
+	t.discWG.Add(1)
 	go func() {
 		server.DiscV5.SearchTopic(t.topic, t.period, found, lookup)
-		t.wg.Done()
+		t.discWG.Done()
 	}()
-	t.wg.Add(1)
+	t.poolWG.Add(1)
 	go func() {
 		t.handleFoundPeers(server, found, lookup)
-		t.wg.Done()
+		t.poolWG.Done()
 	}()
 
 	return nil
@@ -409,15 +410,18 @@ func (t *TopicPool) StopSearch() {
 	case <-t.quit:
 		return
 	default:
+	}
 	log.Debug("stoping search", "topic", t.topic)
+	close(t.quit)
+	t.mu.Lock()
 	if t.fastModeTimeoutCancel != nil {
 		close(t.fastModeTimeoutCancel)
 		t.fastModeTimeoutCancel = nil
 	}
-		close(t.period)
-		t.period = nil
 	t.currentMode = 0
-		close(t.quit)
-	}
-	t.wg.Wait()
+	t.mu.Unlock()
+	// wait for poolWG to exit because it writes to period channel
+	t.poolWG.Wait()
+	close(t.period)
+	t.discWG.Wait()
 }