engine_v2, params: fix unsynchronized reads of V2.CurrentConfig, close XFN-53 (#1642)

consensus/XDPoS/engines/engine_v2/engine.go

@@ -142,14 +142,15 @@ 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
 	}()
 }
 
@@ -254,10 +255,11 @@ 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

consensus/XDPoS/engines/engine_v2/timeout.go

@@ -302,7 +302,7 @@ 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 {
 		log.Warn("[OnCountdownTimeout] timeout sync threadhold reached, send syncInfo message")
 		syncInfo := x.getSyncInfo()
 		x.broadcastToBftChannel(syncInfo)

consensus/XDPoS/engines/engine_v2/verifyHeader.go

@@ -2,6 +2,7 @@ package engine_v2
 
 import (
 	"bytes"
+	"fmt"
 	"math/big"
 	"time"
 

internal/ethapi/api.go

@@ -494,8 +494,8 @@ func (s *PublicBlockChainAPI) GetStorageAt(ctx context.Context, address common.A
 }
 
 // GetBlockReceipts returns the block receipts for the given block hash or number or tag.
-func (api *PublicBlockChainAPI) GetBlockReceipts(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) ([]map[string]interface{}, error) {
-	block, err := api.b.BlockByNumberOrHash(ctx, blockNrOrHash)
+func (s *PublicBlockChainAPI) GetBlockReceipts(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) ([]map[string]interface{}, error) {
+	block, err := s.b.BlockByNumberOrHash(ctx, blockNrOrHash)
 	if err != nil {
 		return nil, err
 	}

params/config.go

@@ -493,7 +493,7 @@ 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
 }
 
@@ -538,18 +538,32 @@ func (v *V2) UpdateConfig(round uint64) {
 	v.CurrentConfig = v.AllConfigs[index]
 }
 
-func (v *V2) Config(round uint64) *V2Config {
+// 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
 
 	//find the right config
-	for i := range v.configIndex {
-		if v.configIndex[i] <= configRound {
-			index = v.configIndex[i]
+	for i := range v2.configIndex {
+		if v2.configIndex[i] <= configRound {
+			index = v2.configIndex[i]
 			break
 		}
 	}
-	return v.AllConfigs[index]
+	return v2.AllConfigs[index]
 }
 
 func (v *V2) BuildConfigIndex() {