etcdserver: support Raft Pre-Vote

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

etcdserver/config.go

@@ -76,6 +76,9 @@ type ServerConfig struct {
 	InitialCorruptCheck bool
 	CorruptCheckTime    time.Duration
 
+	// PreVote is true to enable Raft Pre-Vote.
+	PreVote bool
+
 	Debug bool
 }
 

etcdserver/raft.go

@@ -411,6 +411,7 @@ func startNode(cfg ServerConfig, cl *membership.RaftCluster, ids []types.ID) (id
 		MaxSizePerMsg:   maxSizePerMsg,
 		MaxInflightMsgs: maxInflightMsgs,
 		CheckQuorum:     true,
+		PreVote:         cfg.PreVote,
 	}
 
 	n = raft.StartNode(c, peers)
@@ -445,6 +446,7 @@ func restartNode(cfg ServerConfig, snapshot *raftpb.Snapshot) (types.ID, *member
 		MaxSizePerMsg:   maxSizePerMsg,
 		MaxInflightMsgs: maxInflightMsgs,
 		CheckQuorum:     true,
+		PreVote:         cfg.PreVote,
 	}
 
 	n := raft.RestartNode(c)
@@ -501,6 +503,7 @@ func restartAsStandaloneNode(cfg ServerConfig, snapshot *raftpb.Snapshot) (types
 		MaxSizePerMsg:   maxSizePerMsg,
 		MaxInflightMsgs: maxInflightMsgs,
 		CheckQuorum:     true,
+		PreVote:         cfg.PreVote,
 	}
 	n := raft.RestartNode(c)
 	raftStatus = n.Status

etcdserver/server.go

@@ -258,6 +258,12 @@ type EtcdServer struct {
 // NewServer creates a new EtcdServer from the supplied configuration. The
 // configuration is considered static for the lifetime of the EtcdServer.
 func NewServer(cfg ServerConfig) (srv *EtcdServer, err error) {
+	if cfg.PreVote {
+		plog.Info("Raft Pre-Vote is enabled")
+	} else {
+		plog.Info("Raft Pre-Vote is disabled")
+	}
+
 	st := v2store.New(StoreClusterPrefix, StoreKeysPrefix)
 
 	var (