middleware/file: add test for reload (#361)

This add a highlevel integration test for zone reloading. It also
fixes a data race in the actual reloading process.

middleware/file/lookup.go

@@ -26,13 +26,31 @@ const (
 // Three sets of records are returned, one for the answer, one for authority  and one for the additional section.
 func (z *Zone) Lookup(qname string, qtype uint16, do bool) ([]dns.RR, []dns.RR, []dns.RR, Result) {
 	if qtype == dns.TypeSOA {
+		if !z.NoReload {
+			z.reloadMu.RLock()
+		}
 		return z.lookupSOA(do)
+		if !z.NoReload {
+			z.reloadMu.RUnlock()
+		}
 	}
 	if qtype == dns.TypeNS && qname == z.origin {
+		if !z.NoReload {
+			z.reloadMu.RLock()
+		}
 		return z.lookupNS(do)
+		if !z.NoReload {
+			z.reloadMu.RUnlock()
+		}
 	}
 
+	if !z.NoReload {
+		z.reloadMu.RLock()
+	}
 	elem, res := z.Tree.Search(qname, qtype)
+	if !z.NoReload {
+		z.reloadMu.RUnlock()
+	}
 	if elem == nil {
 		if res == tree.EmptyNonTerminal {
 			return z.emptyNonTerminal(qname, do)

middleware/file/zone.go

@@ -163,22 +163,24 @@ func (z *Zone) Reload() error {
 			select {
 			case event := <-watcher.Events:
 				if event.Op == fsnotify.Write && path.Clean(event.Name) == z.file {
+
 					reader, err := os.Open(z.file)
 					if err != nil {
 						log.Printf("[ERROR] Failed to open `%s' for `%s': %v", z.file, z.origin, err)
 						continue
 					}
-					z.reloadMu.Lock()
 					zone, err := Parse(reader, z.origin, z.file)
 					if err != nil {
 						log.Printf("[ERROR] Failed to parse `%s': %v", z.origin, err)
-						z.reloadMu.Unlock()
 						continue
 					}
+
 					// copy elements we need
+					z.reloadMu.Lock()
 					z.Apex = zone.Apex
 					z.Tree = zone.Tree
 					z.reloadMu.Unlock()
+
 					log.Printf("[INFO] Successfully reloaded zone `%s'", z.origin)
 					z.Notify()
 				}