*: enable prevote by default

conf/config.toml

@@ -19,6 +19,8 @@ tso-save-interval = "3s"
 
 namespace-classifier = "table"
 
+enable-prevote = true
+
 [security]
 # Path of file that contains list of trusted SSL CAs. if set, following four settings shouldn't be empty
 cacert-path = ""

server/config.go

@@ -93,6 +93,11 @@ type Config struct {
 	TickInterval typeutil.Duration `toml:"tick-interval"`
 	// ElectionInterval is the interval for etcd Raft election.
 	ElectionInterval typeutil.Duration `toml:"election-interval"`
+	// Prevote is true to enable Raft Pre-Vote.
+	// If enabled, Raft runs an additional election phase
+	// to check whether it would get enough votes to win
+	// an election, thus minimizing disruptions.
+	PreVote bool `toml:"enable-prevote"`
 
 	Security SecurityConfig `toml:"security" json:"security"`
 
@@ -219,8 +224,9 @@ func (c *Config) Parse(arguments []string) error {
 	}
 
 	// Load config file if specified.
+	var meta *toml.MetaData
 	if c.configFile != "" {
-		err = c.configFromFile(c.configFile)
+		meta, err = c.configFromFile(c.configFile)
 		if err != nil {
 			return errors.Trace(err)
 		}
@@ -248,7 +254,7 @@ func (c *Config) Parse(arguments []string) error {
 		return errors.Errorf("'%s' is an invalid flag", c.FlagSet.Arg(0))
 	}
 
-	err = c.adjust()
+	err = c.adjust(meta)
 	return errors.Trace(err)
 }
 
@@ -275,7 +281,7 @@ func (c *Config) validate() error {
 	return nil
 }
 
-func (c *Config) adjust() error {
+func (c *Config) adjust(meta *toml.MetaData) error {
 	adjustString(&c.Name, defaultName)
 	adjustString(&c.DataDir, fmt.Sprintf("default.%s", c.Name))
 
@@ -333,6 +339,11 @@ func (c *Config) adjust() error {
 	adjustDuration(&c.heartbeatStreamBindInterval, defaultHeartbeatStreamRebindInterval)
 
 	adjustDuration(&c.leaderPriorityCheckInterval, defaultLeaderPriorityCheckInterval)
+
+	// enable PreVote by default
+	if meta == nil || !meta.IsDefined("enable-prevote") {
+		c.PreVote = true
+	}
 	return nil
 }
 
@@ -350,9 +361,9 @@ func (c *Config) String() string {
 }
 
 // configFromFile loads config from file.
-func (c *Config) configFromFile(path string) error {
-	_, err := toml.DecodeFile(path, c)
-	return errors.Trace(err)
+func (c *Config) configFromFile(path string) (*toml.MetaData, error) {
+	meta, err := toml.DecodeFile(path, c)
+	return &meta, errors.Trace(err)
 }
 
 // ScheduleConfig is the schedule configuration.
@@ -629,6 +640,7 @@ func (c *Config) genEmbedEtcdConfig() (*embed.Config, error) {
 	cfg.InitialCluster = c.InitialCluster
 	cfg.ClusterState = c.InitialClusterState
 	cfg.EnablePprof = true
+	cfg.PreVote = c.PreVote
 	cfg.StrictReconfigCheck = !c.disableStrictReconfigCheck
 	cfg.TickMs = uint(c.TickInterval.Duration / time.Millisecond)
 	cfg.ElectionMs = uint(c.ElectionInterval.Duration / time.Millisecond)

server/config_test.go

@@ -34,7 +34,7 @@ func (s *testConfigSuite) TestTLS(c *C) {
 func (s *testConfigSuite) TestBadFormatJoinAddr(c *C) {
 	cfg := NewTestSingleConfig()
 	cfg.Join = "127.0.0.1:2379" // Wrong join addr without scheme.
-	c.Assert(cfg.adjust(), NotNil)
+	c.Assert(cfg.adjust(nil), NotNil)
 }
 
 func (s *testConfigSuite) TestReloadConfig(c *C) {
@@ -62,7 +62,7 @@ func (s *testConfigSuite) TestReloadConfig(c *C) {
 
 func (s *testConfigSuite) TestValidation(c *C) {
 	cfg := NewConfig()
-	c.Assert(cfg.adjust(), IsNil)
+	c.Assert(cfg.adjust(nil), IsNil)
 
 	cfg.Log.File.Filename = path.Join(cfg.DataDir, "test")
 	c.Assert(cfg.validate(), NotNil)

server/coordinator_test.go

@@ -35,7 +35,7 @@ func newTestOperator(regionID uint64, regionEpoch *metapb.RegionEpoch, kind sche
 
 func newTestScheduleConfig() (*ScheduleConfig, *scheduleOption) {
 	cfg := NewConfig()
-	cfg.adjust()
+	cfg.adjust(nil)
 	opt := newScheduleOption(cfg)
 	return &cfg.Schedule, opt
 }

server/join_test.go

@@ -90,7 +90,7 @@ func startPdWith(cfg *Config) (*Server, error) {
 	abortCh := make(chan struct{}, 1)
 
 	go func() {
-		err := cfg.adjust()
+		err := cfg.adjust(nil)
 		if err != nil {
 			errCh <- errors.Trace(err)
 			return

server/testutil.go

@@ -77,7 +77,7 @@ func NewTestSingleConfig() *Config {
 	cfg.ElectionInterval = typeutil.NewDuration(3000 * time.Millisecond)
 	cfg.leaderPriorityCheckInterval = typeutil.NewDuration(100 * time.Millisecond)
 
-	cfg.adjust()
+	cfg.adjust(nil)
 	return cfg
 }