network: re-add addresses to the pool on UnregisterConnectedAddr

That's what we do anyway, but this way we can be a bit more efficient.

pkg/network/discovery.go

@@ -83,6 +83,11 @@ func newDefaultDiscovery(addrs []string, dt time.Duration, ts Transporter) Disco
 // the pool with the given addresses.
 func (d *DefaultDiscovery) BackFill(addrs ...string) {
 	d.lock.Lock()
+	d.backfill(addrs...)
+	d.lock.Unlock()
+}
+
+func (d *DefaultDiscovery) backfill(addrs ...string) {
 	for _, addr := range addrs {
 		if d.badAddrs[addr] || d.connectedAddrs[addr] ||
 			d.unconnectedAddrs[addr] > 0 {
@@ -92,7 +97,6 @@ func (d *DefaultDiscovery) BackFill(addrs ...string) {
 		d.pushToPoolOrDrop(addr)
 	}
 	d.updateNetSize()
-	d.lock.Unlock()
 }
 
 // PoolCount returns the number of the available node addresses.
@@ -187,7 +191,7 @@ func (d *DefaultDiscovery) RegisterGoodAddr(s string, c capability.Capabilities)
 func (d *DefaultDiscovery) UnregisterConnectedAddr(s string) {
 	d.lock.Lock()
 	delete(d.connectedAddrs, s)
-	d.updateNetSize()
+	d.backfill(s)
 	d.lock.Unlock()
 }
 

pkg/network/discovery_test.go

@@ -132,14 +132,13 @@ func TestDefaultDiscoverer(t *testing.T) {
 	for _, addr := range set1 {
 		d.UnregisterConnectedAddr(addr)
 	}
-	assert.Equal(t, 0, len(d.UnconnectedPeers()))
+	assert.Equal(t, 2, len(d.UnconnectedPeers())) // They're re-added automatically.
 	assert.Equal(t, 0, len(d.BadPeers()))
 	assert.Equal(t, len(set1), len(d.GoodPeers()))
-	require.Equal(t, 0, d.PoolCount())
+	require.Equal(t, 2, d.PoolCount())
 
 	// Now make Dial() fail and wait to see addresses in the bad list.
 	atomic.StoreInt32(&ts.retFalse, 1)
-	d.BackFill(set1...)
 	assert.Equal(t, len(set1), d.PoolCount())
 	set1D := d.UnconnectedPeers()
 	sort.Strings(set1D)

pkg/network/server.go

@@ -439,11 +439,9 @@ func (s *Server) run() {
 					s.lock.RUnlock()
 					if !stillConnected {
 						s.discovery.UnregisterConnectedAddr(addr)
-						s.discovery.BackFill(addr)
 					}
 				} else {
 					s.discovery.UnregisterConnectedAddr(addr)
-					s.discovery.BackFill(addr)
 				}
 				updatePeersConnectedMetric(s.PeerCount())
 			} else {