les: fixed discovery init order

les/client.go

@@ -72,6 +72,7 @@ type LightEthereum struct {
 	netRPCService  *ethapi.PublicNetAPI
 
 	p2pServer *p2p.Server
+	p2pConfig *p2p.Config
 }
 
 // New creates an instance of the light client.
@@ -109,6 +110,7 @@ func New(stack *node.Node, config *eth.Config) (*LightEthereum, error) {
 		bloomIndexer:   eth.NewBloomIndexer(chainDb, params.BloomBitsBlocksClient, params.HelperTrieConfirmations),
 		valueTracker:   lpc.NewValueTracker(lespayDb, &mclock.System{}, requestList, time.Minute, 1/float64(time.Hour), 1/float64(time.Hour*100), 1/float64(time.Hour*1000)),
 		p2pServer:      stack.Server(),
+		p2pConfig:      &stack.Config().P2P,
 	}
 	peers.subscribe((*vtSubscription)(leth.valueTracker))
 
@@ -132,11 +134,7 @@ func New(stack *node.Node, config *eth.Config) (*LightEthereum, error) {
 	leth.chainReader = leth.blockchain
 	leth.txPool = light.NewTxPool(leth.chainConfig, leth.blockchain, leth.relay)
 
-	discovery, err := leth.setupDiscovery(&stack.Config().P2P)
-	if err != nil {
-		return nil, err
-	}
-	leth.serverPool = newServerPool(lespayDb, []byte("serverpool:"), leth.valueTracker, discovery, time.Second, nil, &mclock.System{}, config.UltraLightServers)
+	leth.serverPool = newServerPool(lespayDb, []byte("serverpool:"), leth.valueTracker, time.Second, nil, &mclock.System{}, config.UltraLightServers)
 	peers.subscribe(leth.serverPool)
 	leth.dialCandidates = leth.serverPool.dialIterator
 	leth.retriever.softRequestTimeout = leth.serverPool.getTimeout
@@ -300,6 +298,11 @@ func (s *LightEthereum) Protocols() []p2p.Protocol {
 func (s *LightEthereum) Start() error {
 	log.Warn("Light client mode is an experimental feature")
 
+	discovery, err := s.setupDiscovery(s.p2pConfig)
+	if err != nil {
+		return err
+	}
+	s.serverPool.addSource(discovery)
 	s.serverPool.start()
 	// Start bloom request workers.
 	s.wg.Add(bloomServiceThreads)

les/serverpool.go

@@ -131,7 +131,7 @@ var (
 )
 
 // newServerPool creates a new server pool
-func newServerPool(db ethdb.KeyValueStore, dbKey []byte, vt *lpc.ValueTracker, discovery enode.Iterator, mixTimeout time.Duration, query queryFunc, clock mclock.Clock, trustedURLs []string) *serverPool {
+func newServerPool(db ethdb.KeyValueStore, dbKey []byte, vt *lpc.ValueTracker, mixTimeout time.Duration, query queryFunc, clock mclock.Clock, trustedURLs []string) *serverPool {
 	s := &serverPool{
 		db:           db,
 		clock:        clock,
@@ -147,9 +147,6 @@ func newServerPool(db ethdb.KeyValueStore, dbKey []byte, vt *lpc.ValueTracker, d
 	alwaysConnect := lpc.NewQueueIterator(s.ns, sfAlwaysConnect, sfDisableSelection, true, nil)
 	s.mixSources = append(s.mixSources, knownSelector)
 	s.mixSources = append(s.mixSources, alwaysConnect)
-	if discovery != nil {
-		s.mixSources = append(s.mixSources, discovery)
-	}
 
 	iter := enode.Iterator(s.mixer)
 	if query != nil {
@@ -175,6 +172,13 @@ func newServerPool(db ethdb.KeyValueStore, dbKey []byte, vt *lpc.ValueTracker, d
 	return s
 }
 
+// addSource adds a node discovery source to the server pool (should be called before start)
+func (s *serverPool) addSource(source enode.Iterator) {
+	if source != nil {
+		s.mixSources = append(s.mixSources, source)
+	}
+}
+
 // addPreNegFilter installs a node filter mechanism that performs a pre-negotiation query.
 // Nodes that are filtered out and does not appear on the output iterator are put back
 // into redialWait state.

les/serverpool_test.go

@@ -145,7 +145,8 @@ func (s *serverPoolTest) start() {
 	}
 
 	s.vt = lpc.NewValueTracker(s.db, s.clock, requestList, time.Minute, 1/float64(time.Hour), 1/float64(time.Hour*100), 1/float64(time.Hour*1000))
-	s.sp = newServerPool(s.db, []byte("serverpool:"), s.vt, s.input, 0, testQuery, s.clock, s.trusted)
+	s.sp = newServerPool(s.db, []byte("serverpool:"), s.vt, 0, testQuery, s.clock, s.trusted)
+	s.sp.addSource(s.input)
 	s.sp.validSchemes = enode.ValidSchemesForTesting
 	s.sp.unixTime = func() int64 { return int64(s.clock.Now()) / int64(time.Second) }
 	s.disconnect = make(map[int][]int)