p2p/enode: implement dynamic FairMix timeouts

p2p/enode/iter.go

@@ -146,6 +146,7 @@ type FairMix struct {
 type mixSource struct {
 	it      Iterator
 	next    chan *Node
+	timeout time.Duration
 }
 
 // NewFairMix creates a mixer.
@@ -172,7 +173,7 @@ func (m *FairMix) AddSource(it Iterator) {
 		return
 	}
 	m.wg.Add(1)
-	source := &mixSource{it, make(chan *Node)}
+	source := &mixSource{it, make(chan *Node), m.timeout}
 	m.sources = append(m.sources, source)
 	go m.runSource(m.closed, source)
 }
@@ -215,11 +216,13 @@ func (m *FairMix) Next() bool {
 		case n, ok := <-source.next:
 			if ok {
 				m.cur = n
+				source.timeout = m.timeout
 				return true
 			}
 			// This source has ended.
 			m.deleteSource(source)
 		case <-timeout:
+			source.timeout /= 2
 			return m.nextFromAny()
 		}
 	}