eth/downloader: use count instead of peers, clearer

eth/downloader/downloader.go

@@ -363,7 +363,7 @@ out:
 				}
 			}
 			// After removing bad peers make sure we actually have sufficient peer left to keep downloading
-			if d.peers.Peers() == 0 {
+			if d.peers.Len() == 0 {
 				d.queue.Reset()
 				return errNoPeers
 			}
@@ -400,7 +400,7 @@ out:
 				if d.queue.InFlight() == 0 {
 					d.queue.Reset()
 
-					return fmt.Errorf("%v peers available = %d. total peers = %d. hashes needed = %d", errPeersUnavailable, len(idlePeers), d.peers.Peers(), d.queue.Pending())
+					return fmt.Errorf("%v peers available = %d. total peers = %d. hashes needed = %d", errPeersUnavailable, len(idlePeers), d.peers.Len(), d.queue.Pending())
 				}
 
 			} else if d.queue.InFlight() == 0 {

eth/downloader/peer.go

@@ -154,8 +154,8 @@ func (ps *peerSet) Peer(id string) *peer {
 	return ps.peers[id]
 }
 
-// Peers returns if the current number of peers in the set.
-func (ps *peerSet) Peers() int {
+// Len returns if the current number of peers in the set.
+func (ps *peerSet) Len() int {
 	ps.lock.RLock()
 	defer ps.lock.RUnlock()