From 5a26279c1cfca04548e571226320880118278135 Mon Sep 17 00:00:00 2001
From: Daniel Liu <139250065@qq.com>
Date: Mon, 3 Nov 2025 17:21:54 +0800
Subject: [PATCH] engine_v2, params: fix unsynchronized reads of
 V2.CurrentConfig, close XFN-53 (#1642)

---
 consensus/XDPoS/engines/engine_v2/engine.go  | 12 +++++++-----
 consensus/XDPoS/engines/engine_v2/timeout.go |  2 +-
 params/config.go                             | 16 +++++++++++++++-
 3 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/consensus/XDPoS/engines/engine_v2/engine.go b/consensus/XDPoS/engines/engine_v2/engine.go
index 260fdd19ff..5725beb9b6 100644
--- a/consensus/XDPoS/engines/engine_v2/engine.go
+++ b/consensus/XDPoS/engines/engine_v2/engine.go
@@ -150,14 +150,15 @@ func (x *XDPoS_v2) UpdateParams(header *types.Header) {
 	x.config.V2.UpdateConfig(uint64(round))
 
 	// Setup timeoutTimer
-	duration := time.Duration(x.config.V2.CurrentConfig.TimeoutPeriod) * time.Second
-	err = x.timeoutWorker.SetParams(duration, x.config.V2.CurrentConfig.ExpTimeoutConfig.Base, x.config.V2.CurrentConfig.ExpTimeoutConfig.MaxExponent)
+	currentConfig := x.config.V2.GetCurrentConfig()
+	duration := time.Duration(currentConfig.TimeoutPeriod) * time.Second
+	err = x.timeoutWorker.SetParams(duration, currentConfig.ExpTimeoutConfig.Base, currentConfig.ExpTimeoutConfig.MaxExponent)
 	if err != nil {
 		log.Error("[UpdateParams] set params failed", "err", err)
 	}
 	// avoid deadlock
 	go func() {
-		x.minePeriodCh <- x.config.V2.CurrentConfig.MinePeriod
+		x.minePeriodCh <- currentConfig.MinePeriod
 	}()
 }
 
@@ -261,10 +262,11 @@ func (x *XDPoS_v2) initial(chain consensus.ChainReader, header *types.Header) er
 	}
 
 	// Initial timeout
-	log.Warn("[initial] miner wait period", "period", x.config.V2.CurrentConfig.MinePeriod)
+	currentConfig := x.config.V2.GetCurrentConfig()
+	log.Warn("[initial] miner wait period", "period", currentConfig.MinePeriod)
 	// avoid deadlock
 	go func() {
-		x.minePeriodCh <- x.config.V2.CurrentConfig.MinePeriod
+		x.minePeriodCh <- currentConfig.MinePeriod
 	}()
 
 	// Kick-off the countdown timer
diff --git a/consensus/XDPoS/engines/engine_v2/timeout.go b/consensus/XDPoS/engines/engine_v2/timeout.go
index 0a57de31a4..729d8f982d 100644
--- a/consensus/XDPoS/engines/engine_v2/timeout.go
+++ b/consensus/XDPoS/engines/engine_v2/timeout.go
@@ -324,7 +324,7 @@ func (x *XDPoS_v2) OnCountdownTimeout(time time.Time, chain interface{}) error {
 	}
 
 	x.timeoutCount++
-	if x.timeoutCount%x.config.V2.CurrentConfig.TimeoutSyncThreshold == 0 {
+	if x.timeoutCount%x.config.V2.GetCurrentConfig().TimeoutSyncThreshold == 0 {
 		syncInfo := x.getSyncInfo()
 		log.Info("[OnCountdownTimeout] Timeout sync threshold reached, send syncInfo message", "QC round", syncInfo.HighestQuorumCert.ProposedBlockInfo.Round, "QC num", syncInfo.HighestQuorumCert.ProposedBlockInfo.Number, "QC sigs", len(syncInfo.HighestQuorumCert.Signatures), "TC round", syncInfo.HighestTimeoutCert.Round, "TC sigs", len(syncInfo.HighestTimeoutCert.Signatures))
 		x.broadcastToBftChannel(syncInfo)
diff --git a/params/config.go b/params/config.go
index 7fc254f38d..a058731699 100644
--- a/params/config.go
+++ b/params/config.go
@@ -560,7 +560,7 @@ func (v2 *V2) Description(indent int) string {
 	banner += fmt.Sprintf("%s- SwitchEpoch: %v\n", prefix, v2.SwitchEpoch)
 	banner += fmt.Sprintf("%s- SwitchBlock: %v\n", prefix, v2.SwitchBlock)
 	banner += fmt.Sprintf("%s- SkipV2Validation: %v\n", prefix, v2.SkipV2Validation)
-	banner += fmt.Sprintf("%s- %s", prefix, v2.CurrentConfig.Description("CurrentConfig", indent+2))
+	banner += fmt.Sprintf("%s- %s", prefix, v2.GetCurrentConfig().Description("CurrentConfig", indent+2))
 	return banner
 }
 
@@ -625,6 +625,20 @@ func (v2 *V2) UpdateConfig(round uint64) {
 	v2.CurrentConfig = v2.AllConfigs[index]
 }
 
+// GetCurrentConfig returns a opy of the current config, it assumes v2 is not nil
+func (v2 *V2) GetCurrentConfig() *V2Config {
+	v2.lock.RLock()
+	defer v2.lock.RUnlock()
+
+	if v2.CurrentConfig == nil {
+		return nil
+	}
+
+	// avoid CurrentConfig is changed by other goroutines
+	cpyConfig := *v2.CurrentConfig
+	return &cpyConfig
+}
+
 func (v2 *V2) Config(round uint64) *V2Config {
 	configRound := round
 	var index uint64