clean up old config only when peers are changed.

fix https://github.com/chrislusf/seaweedfs/issues/307

go/weed/glide.lock

@@ -1,5 +1,5 @@
 hash: 97328ff2a0b9e682660bd51e424a7f850388df96bd153fa6f9ee419c993065c1
-updated: 2016-05-23T14:27:00.216163267-07:00
+updated: 2016-05-24T10:27:49.252798956-07:00
 imports:
 - name: bazil.org/fuse
   version: 5d02b06737b3b3c2e6a44e03348b6f2b44aa6835
@@ -12,26 +12,6 @@ imports:
   version: 90f631ee823c83f594f27257bab64911190856af
   subpackages:
   - protobuf
-- name: github.com/chrislusf/seaweedfs
-  version: dfde029430fabd7fc29b8e4f61d1e80b64d6a4de
-  subpackages:
-  - go/filer
-  - go/glog
-  - go/operation
-  - go/security
-  - go/storage
-  - go/util
-  - go/weed/weed_server
-  - go/filer/cassandra_store
-  - go/filer/embedded_filer
-  - go/filer/flat_namespace
-  - go/filer/redis_store
-  - go/images
-  - go/sequence
-  - go/stats
-  - go/topology
-  - go/weed/weed_server/master_ui
-  - go/weed/weed_server/volume_server_ui
 - name: github.com/dgrijalva/jwt-go
   version: 40bd0f3b4891a9d7f121bfb7b8e8b0525625e262
 - name: github.com/disintegration/imaging

go/weed/weed_server/raft_server.go

@@ -11,6 +11,8 @@ import (
 	"net/url"
 	"os"
 	"path"
+	"reflect"
+	"sort"
 	"strings"
 	"time"
 
@@ -49,8 +51,9 @@ func NewRaftServer(r *mux.Router, peers []string, httpAddr string, dataDir strin
 	transporter.Transport.MaxIdleConnsPerHost = 1024
 	glog.V(1).Infof("Starting RaftServer with IP:%v:", httpAddr)
 
-	// Clear old cluster configurations if peers are set
-	if len(s.peers) > 0 {
+	// Clear old cluster configurations if peers are changed
+	if oldPeers, changed := isPeersChanged(s.dataDir, httpAddr, s.peers); changed {
+		glog.V(0).Infof("Peers Change: %v => %v", oldPeers, s.peers)
 		os.RemoveAll(path.Join(s.dataDir, "conf"))
 		os.RemoveAll(path.Join(s.dataDir, "log"))
 		os.RemoveAll(path.Join(s.dataDir, "snapshot"))
@@ -71,6 +74,7 @@ func NewRaftServer(r *mux.Router, peers []string, httpAddr string, dataDir strin
 
 	if len(s.peers) > 0 {
 		// Join to leader if specified.
+		for {
 			glog.V(0).Infoln("Joining cluster:", strings.Join(s.peers, ","))
 			time.Sleep(time.Duration(rand.Intn(1000)) * time.Millisecond)
 			firstJoinError := s.Join(s.peers)
@@ -82,7 +86,11 @@ func NewRaftServer(r *mux.Router, peers []string, httpAddr string, dataDir strin
 				})
 				if err != nil {
 					glog.V(0).Infoln(err)
-				return nil
+				} else {
+					break
+				}
+			} else {
+				break
 			}
 		}
 	} else if s.raftServer.IsLogEmpty() {
@@ -116,6 +124,30 @@ func (s *RaftServer) Peers() (members []string) {
 	return
 }
 
+func isPeersChanged(dir string, self string, peers []string) (oldPeers []string, changed bool) {
+	confPath := path.Join(dir, "conf")
+	// open conf file
+	b, err := ioutil.ReadFile(confPath)
+	if err != nil {
+		return oldPeers, true
+	}
+	conf := &raft.Config{}
+	if err = json.Unmarshal(b, conf); err != nil {
+		return oldPeers, true
+	}
+
+	for _, p := range conf.Peers {
+		oldPeers = append(oldPeers, strings.TrimPrefix(p.ConnectionString, "http://"))
+	}
+	oldPeers = append(oldPeers, self)
+
+	sort.Strings(peers)
+	sort.Strings(oldPeers)
+
+	return oldPeers, reflect.DeepEqual(peers, oldPeers)
+
+}
+
 // Join joins an existing cluster.
 func (s *RaftServer) Join(peers []string) error {
 	command := &raft.DefaultJoinCommand{