bugfix: ConnectionMulti update addresses data race

We need to update an addresses slice under a lock because
we use the slice in ConnectionMulti.getCurrentConnection().

Part of #218

Author: oleg-jukovec

multi/multi.go

@@ -212,7 +212,9 @@ func (connMulti *ConnectionMulti) checker() {
 						connMulti.deleteConnectionFromPool(v)
 					}
 				}
+				connMulti.mutex.Lock()
 				connMulti.addrs = addrs
+				connMulti.mutex.Unlock()
 			}
 		case <-timer.C:
 			for _, addr := range connMulti.addrs {

multi/multi_test.go

@@ -200,13 +200,18 @@ func TestRefresh(t *testing.T) {
 		t.Errorf("conn is nil after Connect")
 		return
 	}
+
+	multiConn.mutex.RLock()
 	curAddr := multiConn.addrs[0]
+	multiConn.mutex.RUnlock()
 
 	// Wait for refresh timer.
 	// Scenario 1 nodeload, 1 refresh, 1 nodeload.
 	time.Sleep(10 * time.Second)
 
+	multiConn.mutex.RLock()
 	newAddr := multiConn.addrs[0]
+	multiConn.mutex.RUnlock()
 
 	if curAddr == newAddr {
 		t.Errorf("Expect address refresh")