make pre-vote enabled by default

Author: dhiaayachi

api.go

@@ -214,8 +214,9 @@ type Raft struct {
 	// mainThreadSaturation measures the saturation of the main raft goroutine.
 	mainThreadSaturation *saturationMetric
 
-	// preVote control if the pre-vote feature is activated
-	preVote bool
+	// preVoteDisabled control if the pre-vote feature is activated,
+	// prevote feature is disabled if set to true.
+	preVoteDisabled bool
 }
 
 // BootstrapCluster initializes a server's storage with the given cluster
@@ -564,7 +565,7 @@ func NewRaft(conf *Config, fsm FSM, logs LogStore, stable StableStore, snaps Sna
 		leaderNotifyCh:        make(chan struct{}, 1),
 		followerNotifyCh:      make(chan struct{}, 1),
 		mainThreadSaturation:  newSaturationMetric([]string{"raft", "thread", "main", "saturation"}, 1*time.Second),
-		preVote:               conf.PreVote && transportSupportPreVote,
+		preVoteDisabled:       conf.PreVoteDisabled || !transportSupportPreVote,
 	}
 
 	r.conf.Store(*conf)

config.go

@@ -232,8 +232,8 @@ type Config struct {
 	// raft's configuration and index values.
 	NoSnapshotRestoreOnStart bool
 
-	// PreVote activate the pre-vote feature
-	PreVote bool
+	// PreVoteDisabled deactivate the pre-vote feature when set to true
+	PreVoteDisabled bool
 
 	// skipStartup allows NewRaft() to bypass all background work goroutines
 	skipStartup bool

raft-compat/prevote_test.go

@@ -89,7 +89,7 @@ func TestRaft_PreVote_BootStrap_PreVote(t *testing.T) {
 
 				//Create an upgraded node with the store
 				rUIT := testcluster.InitUITWithStore(t, id, store.(*raftprevious.InmemStore), func(config *raft.Config) {
-					config.PreVote = tc.preVote
+					config.PreVoteDisabled = !tc.preVote
 				})
 				future := getLeader.GetRaft().(*raftprevious.Raft).AddVoter(raftprevious.ServerID(rUIT.GetLocalID()), raftprevious.ServerAddress(rUIT.GetLocalAddr()), 0, 0)
 				utils.WaitFuture(t, future)
@@ -124,7 +124,7 @@ func TestRaft_PreVote_BootStrap_PreVote(t *testing.T) {
 			require.NotEmpty(t, getLeader)
 
 			// Create a new node to replace the deleted one
-			rUIT := testcluster.InitUITWithStore(t, id, store.(*raftprevious.InmemStore), func(config *raft.Config) { config.PreVote = true })
+			rUIT := testcluster.InitUITWithStore(t, id, store.(*raftprevious.InmemStore), func(config *raft.Config) { config.PreVoteDisabled = false })
 			fa := getLeader.GetRaft().(*raft.Raft).AddVoter(raft.ServerID(rUIT.GetLocalID()), raft.ServerAddress(rUIT.GetLocalAddr()), 0, 0)
 			utils.WaitFuture(t, fa)
 

raft.go

@@ -291,11 +291,9 @@ func (r *Raft) runCandidate() {
 	var voteCh <-chan *voteResult
 	var prevoteCh <-chan *preVoteResult
 
-	// check if pre-vote is active and that this is not a leader transfer
-
-	// Leader transfer do not perform prevote by design, as the selected server is very likely to be fit
-	// and an election will happen in all cases.
-	if r.preVote && !r.candidateFromLeadershipTransfer.Load() {
+	// check if pre-vote is active and that this is not a leader transfer.
+	// Leader transfer do not perform prevote by design
+	if !r.preVoteDisabled && !r.candidateFromLeadershipTransfer.Load() {
 		prevoteCh = r.preElectSelf()
 	} else {
 		voteCh = r.electSelf()

raft_test.go

@@ -2091,13 +2091,13 @@ func TestRaft_PreVoteMixedCluster(t *testing.T) {
 			}
 
 			conf := inmemConfig(t)
-			conf.PreVote = tc.prevoteNum > tc.noprevoteNum
+			conf.PreVoteDisabled = tc.prevoteNum <= tc.noprevoteNum
 			c := MakeCluster(majority, t, conf)
 			defer c.Close()
 
 			// Set up another server speaking protocol version 2.
 			conf = inmemConfig(t)
-			conf.PreVote = tc.prevoteNum < tc.noprevoteNum
+			conf.PreVoteDisabled = tc.prevoteNum >= tc.noprevoteNum
 			c1 := MakeClusterNoBootstrap(minority, t, conf)
 
 			// Merge clusters.
@@ -2126,7 +2126,7 @@ func TestRaft_PreVoteMixedCluster(t *testing.T) {
 func TestRaft_PreVoteAvoidElectionWithPartition(t *testing.T) {
 	// Make a prevote cluster.
 	conf := inmemConfig(t)
-	conf.PreVote = true
+	conf.PreVoteDisabled = false
 	c := MakeCluster(5, t, conf)
 	defer c.Close()