vendor-ed skydns

vendor/github.com/skynetservices/skydns/server/backend.go

@@ -0,0 +1,46 @@
+// Copyright (c) 2014 The SkyDNS Authors. All rights reserved.
+// Use of this source code is governed by The MIT License (MIT) that can be
+// found in the LICENSE file.
+
+package server
+
+import "github.com/skynetservices/skydns/msg"
+
+type Backend interface {
+	Records(name string, exact bool) ([]msg.Service, error)
+	ReverseRecord(name string) (*msg.Service, error)
+}
+
+// FirstBackend exposes the Backend interface over multiple Backends, returning
+// the first Backend that answers the provided record request. If no Backend answers
+// a record request, the last error seen will be returned.
+type FirstBackend []Backend
+
+// FirstBackend implements Backend
+var _ Backend = FirstBackend{}
+
+func (g FirstBackend) Records(name string, exact bool) (records []msg.Service, err error) {
+	var lastError error
+	for _, backend := range g {
+		if records, err = backend.Records(name, exact); err == nil && len(records) > 0 {
+			return records, nil
+		}
+		if err != nil {
+			lastError = err
+		}
+	}
+	return nil, lastError
+}
+
+func (g FirstBackend) ReverseRecord(name string) (record *msg.Service, err error) {
+	var lastError error
+	for _, backend := range g {
+		if record, err = backend.ReverseRecord(name); err == nil && record != nil {
+			return record, nil
+		}
+		if err != nil {
+			lastError = err
+		}
+	}
+	return nil, lastError
+}