eth: cleaner declaration of discovery iterators

No functional change, just easier to read.

Signed-off-by: Csaba Kiraly <[email protected]>

Author: cskiraly

eth/backend.go

@@ -521,12 +521,10 @@ func (s *Ethereum) setupDiscovery() error {
 	if s.p2pServer.DiscoveryV4() != nil {
 		fairmix := enode.NewFairMix(0)
 		for i := 0; i < discoveryParallelLookups; i++ {
-			asyncFilter := s.p2pServer.DiscoveryV4().RequestENR
-			filter := eth.NewNodeFilter(s.blockchain)
-			iter := enode.AsyncFilter(
-				enode.NewBufferIter(s.p2pServer.DiscoveryV4().RandomNodes(), discoveryPrefetchBuffer),
-				asyncFilter, maxParallelENRRequests)
-			iter = enode.Filter(iter, filter)
+			iter := s.p2pServer.DiscoveryV4().RandomNodes()
+			iter = enode.NewBufferIter(iter, discoveryPrefetchBuffer)
+			iter = enode.AsyncFilter(iter, s.p2pServer.DiscoveryV4().RequestENR, maxParallelENRRequests)
+			iter = enode.Filter(iter, eth.NewNodeFilter(s.blockchain))
 			fairmix.AddSource(iter, fmt.Sprintf("DiscoveryV4-%d", i))
 		}
 		s.discmix.AddSource(fairmix, "DiscoveryV4")
@@ -536,10 +534,10 @@ func (s *Ethereum) setupDiscovery() error {
 	if s.p2pServer.DiscoveryV5() != nil {
 		fairmix := enode.NewFairMix(0)
 		for i := 0; i < discoveryParallelLookups; i++ {
-			iter := enode.NewBufferIter(s.p2pServer.DiscoveryV5().RandomNodes(), discoveryPrefetchBuffer)
-			filter := eth.NewNodeFilter(s.blockchain)
-			filterIter := enode.Filter(iter, filter)
-			fairmix.AddSource(filterIter, fmt.Sprintf("DiscoveryV5-%d", i))
+			iter := s.p2pServer.DiscoveryV5().RandomNodes()
+			iter = enode.NewBufferIter(iter, discoveryPrefetchBuffer)
+			iter = enode.Filter(iter, eth.NewNodeFilter(s.blockchain))
+			fairmix.AddSource(iter, fmt.Sprintf("DiscoveryV5-%d", i))
 		}
 		s.discmix.AddSource(fairmix, "DiscoveryV5")
 	}