From ebb8d781b555a0a603cc63373f58b7a72faf2a56 Mon Sep 17 00:00:00 2001
From: Yicheng Qin <qycqycqycqycqyc@gmail.com>
Date: Thu, 29 Jan 2015 16:04:33 -0800
Subject: [PATCH] server: standby exits when detecting v2 is running

---
 server/standby_server.go | 41 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/server/standby_server.go b/server/standby_server.go
index d0b35f737..ed8f7b314 100644
--- a/server/standby_server.go
+++ b/server/standby_server.go
@@ -187,6 +187,14 @@ func (s *StandbyServer) monitorCluster() {
 		case <-ticker.C:
 		}
 
+		ok, err := s.checkMemberInternalVersionIsV2()
+		if err != nil {
+			log.Warnf("fail checking internal version(%v): %v", s.ClusterURLs(), err)
+		} else if ok {
+			log.Infof("Detect the cluster has been upgraded to v2. Exit now.")
+			os.Exit(0)
+		}
+
 		if err := s.syncCluster(nil); err != nil {
 			log.Warnf("fail syncing cluster(%v): %v", s.ClusterURLs(), err)
 			continue
@@ -216,6 +224,39 @@ func (s *StandbyServer) monitorCluster() {
 	}
 }
 
+func (s *StandbyServer) checkMemberInternalVersionIsV2() (bool, error) {
+	c := &http.Client{Transport: s.client.Client.Transport}
+	for _, memb := range s.Cluster {
+		url := memb.ClientURL
+		resp, err := c.Get(url + "/version")
+		if err != nil {
+			log.Debugf("failed to get /version from %s", url)
+			continue
+		}
+		b, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			log.Debugf("failed to read body from %s", url)
+			continue
+		}
+
+		var m map[string]string
+		err = json.Unmarshal(b, &m)
+		if err != nil {
+			log.Debugf("failed to unmarshal body %s from %s", b, url)
+			continue
+		}
+		switch m["internalVersion"] {
+		case "1":
+			return false, nil
+		case "2":
+			return true, nil
+		default:
+			log.Warnf("unrecognized internal version %s from %s", m["internalVersion"], url)
+		}
+	}
+	return false, fmt.Errorf("failed to get version")
+}
+
 func (s *StandbyServer) syncCluster(peerURLs []string) error {
 	peerURLs = append(s.ClusterURLs(), peerURLs...)