server: simplify mode transition

etcd/etcd.go

@@ -63,10 +63,11 @@ type Server struct {
 	nodes  map[string]bool
 	client *v2client
 	t      *transporter
+	node   *v2Raft
+	store.Store
 
 	// participant mode vars
 	proposal    chan v2Proposal
-	node        *v2Raft
 	addNodeC    chan raft.Config
 	removeNodeC chan raft.Config
 
@@ -75,8 +76,6 @@ type Server struct {
 	leaderAddr  string
 	clusterConf *config.ClusterConfig
 
-	store.Store
-
 	modeC chan int
 	stop  chan struct{}
 
@@ -105,21 +104,20 @@ func New(c *config.Config, id int64) *Server {
 		id:           id,
 		pubAddr:      c.Addr,
 		raftPubAddr:  c.Peer.Addr,
+		tickDuration: defaultTickDuration,
+
 		nodes:  make(map[string]bool),
 		client: newClient(tc),
 		t:      newTransporter(tc),
-		tickDuration: defaultTickDuration,
-
+		node: &v2Raft{
+			Node:   raft.New(id, defaultHeartbeat, defaultElection),
+			result: make(map[wait]chan interface{}),
+		},
 		Store: store.New(),
 
 		modeC: make(chan int, 10),
 		stop:  make(chan struct{}),
 	}
-	node := &v2Raft{
-		Node:   raft.New(id, defaultHeartbeat, defaultElection),
-		result: make(map[wait]chan interface{}),
-	}
-	s.initParticipant(node)
 
 	for _, seed := range c.Peers {
 		s.nodes[seed] = true
@@ -306,18 +304,17 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-func (s *Server) initParticipant(node *v2Raft) {
+func (s *Server) initParticipant() {
 	s.proposal = make(chan v2Proposal, maxBufferedProposal)
-	s.node = node
 	s.addNodeC = make(chan raft.Config, 1)
 	s.removeNodeC = make(chan raft.Config, 1)
 	s.t.start()
 }
 
-func (s *Server) initStandby(leader int64, leaderAddr string, conf *config.ClusterConfig) {
-	s.leader = leader
-	s.leaderAddr = leaderAddr
-	s.clusterConf = conf
+func (s *Server) initStandby() {
+	s.leader = noneId
+	s.leaderAddr = ""
+	s.clusterConf = config.NewClusterConfig()
 }
 
 func (s *Server) run() {
@@ -329,8 +326,10 @@ func (s *Server) run() {
 
 		switch s.mode {
 		case participant:
+			s.initParticipant()
 			s.runParticipant()
 		case standby:
+			s.initStandby()
 			s.runStandby()
 		case stop:
 			return
@@ -387,20 +386,15 @@ func (s *Server) runParticipant() {
 	}
 
 	log.Printf("Node: %d removed to standby mode\n", s.id)
-	leader := noneId
-	leaderAddr := ""
-	if s.node.HasLeader() && !s.node.IsLeader() {
-		leader = s.node.Leader()
-		leaderAddr = s.fetchAddrFromStore(s.leader)
-	}
-	conf := s.ClusterConfig()
-	s.initStandby(leader, leaderAddr, conf)
 	s.mode = standby
 	return
 }
 
 func (s *Server) runStandby() {
 	syncDuration := time.Duration(int64(s.clusterConf.SyncInterval * float64(time.Second)))
+	if err := s.syncCluster(); err != nil {
+		log.Println("standby sync:", err)
+	}
 	for {
 		select {
 		case <-time.After(syncDuration):
@@ -410,9 +404,14 @@ func (s *Server) runStandby() {
 		}
 
 		if err := s.syncCluster(); err != nil {
+			log.Println("standby sync:", err)
 			continue
 		}
-		if err := s.standbyJoin(s.leaderAddr); err != nil {
+		if s.clusterConf.ActiveSize <= len(s.nodes) {
+			continue
+		}
+		if err := s.joinByPeer(s.leaderAddr); err != nil {
+			log.Println("standby join:", err)
 			continue
 		}
 		break
@@ -422,12 +421,11 @@ func (s *Server) runStandby() {
 	// TODO(yichengq): use old v2Raft
 	// 1. reject proposal in leader state when sm is removed
 	// 2. record removeIndex in node to ignore msgDenial and old removal
-	s.Store = store.New()
-	node := &v2Raft{
+	s.node = &v2Raft{
 		Node:   raft.New(s.id, defaultHeartbeat, defaultElection),
 		result: make(map[wait]chan interface{}),
 	}
-	s.initParticipant(node)
+	s.Store = store.New()
 	s.mode = participant
 	return
 }
@@ -530,10 +528,7 @@ func (s *Server) fetchAddrFromStore(nodeId int64) string {
 	return ""
 }
 
-func (s *Server) standbyJoin(addr string) error {
-	if s.clusterConf.ActiveSize <= len(s.nodes) {
-		return fmt.Errorf("full cluster")
-	}
+func (s *Server) joinByPeer(addr string) error {
 	info := &context{
 		MinVersion: store.MinVersion(),
 		MaxVersion: store.MaxVersion(),