Base fee change denominator as genesis parameter (0xPolygon#1934)

* Base fee change denominator as genesis parameter

* Go lint fix

* CR fix

blockchain/blockchain.go

@@ -19,9 +19,6 @@ import (
 )
 
 const (
-	// defaultBaseFeeChangeDenom is the value to bound the amount the base fee can change between blocks.
-	defaultBaseFeeChangeDenom = 8
-
 	// blockGasTargetDivisor is the bound divisor of the gas limit, used in update calculations
 	blockGasTargetDivisor uint64 = 1024
 
@@ -1381,22 +1378,22 @@ func (b *Blockchain) CalculateBaseFee(parent *types.Header) uint64 {
 	// If the parent block used more gas than its target, the baseFee should increase.
 	if parent.GasUsed > parentGasTarget {
 		gasUsedDelta := parent.GasUsed - parentGasTarget
-		baseFeeDelta := calcBaseFeeDelta(gasUsedDelta, parentGasTarget, parent.BaseFee)
+		baseFeeDelta := b.calcBaseFeeDelta(gasUsedDelta, parentGasTarget, parent.BaseFee)
 
 		return parent.BaseFee + common.Max(baseFeeDelta, 1)
 	}
 
 	// Otherwise, if the parent block used less gas than its target, the baseFee should decrease.
 	gasUsedDelta := parentGasTarget - parent.GasUsed
-	baseFeeDelta := calcBaseFeeDelta(gasUsedDelta, parentGasTarget, parent.BaseFee)
+	baseFeeDelta := b.calcBaseFeeDelta(gasUsedDelta, parentGasTarget, parent.BaseFee)
 
 	return common.Max(parent.BaseFee-baseFeeDelta, 0)
 }
 
-func calcBaseFeeDelta(gasUsedDelta, parentGasTarget, baseFee uint64) uint64 {
+func (b *Blockchain) calcBaseFeeDelta(gasUsedDelta, parentGasTarget, baseFee uint64) uint64 {
 	y := baseFee * gasUsedDelta / parentGasTarget
 
-	return y / defaultBaseFeeChangeDenom
+	return y / b.config.Params.BaseFeeChangeDenom
 }
 
 func (b *Blockchain) writeBatchAndUpdate(

blockchain/blockchain_test.go

@@ -1396,6 +1396,7 @@ func TestBlockchain_CalculateBaseFee(t *testing.T) {
 						Forks: &chain.Forks{
 							chain.London: chain.NewFork(5),
 						},
+						BaseFeeChangeDenom: chain.BaseFeeChangeDenom,
 					},
 					Genesis: &chain.Genesis{
 						BaseFeeEM: test.elasticityMultiplier,

chain/chain.go

@@ -24,6 +24,9 @@ const (
 
 	// GenesisDifficulty is the default difficulty of the Genesis block.
 	GenesisDifficulty uint64 = 131072
+
+	// BaseFeeChangeDenom is the value to bound the amount the base fee can change between blocks
+	BaseFeeChangeDenom = uint64(8)
 )
 
 var (

chain/params.go

@@ -32,6 +32,9 @@ type Params struct {
 	BurnContract map[uint64]types.Address `json:"burnContract"`
 	// Destination address to initialize default burn contract with
 	BurnContractDestinationAddress types.Address `json:"burnContractDestinationAddress,omitempty"`
+
+	// BaseFeeChangeDenom is the value to bound the amount the base fee can change between blocks
+	BaseFeeChangeDenom uint64 `json:"baseFeeChangeDenom,omitempty"`
 }
 
 type AddressListConfig struct {

command/default.go

@@ -8,13 +8,14 @@ import (
 )
 
 const (
-	DefaultGenesisFileName  = "genesis.json"
-	DefaultChainName        = "polygon-edge"
-	DefaultChainID          = 100
-	DefaultConsensus        = server.PolyBFTConsensus
-	DefaultGenesisGasUsed   = 458752  // 0x70000
-	DefaultGenesisGasLimit  = 5242880 // 0x500000
-	DefaultGenesisBaseFeeEM = chain.GenesisBaseFeeEM
+	DefaultGenesisFileName           = "genesis.json"
+	DefaultChainName                 = "polygon-edge"
+	DefaultChainID                   = 100
+	DefaultConsensus                 = server.PolyBFTConsensus
+	DefaultGenesisGasUsed            = 458752  // 0x70000
+	DefaultGenesisGasLimit           = 5242880 // 0x500000
+	DefaultGenesisBaseFeeEM          = chain.GenesisBaseFeeEM
+	DefaultGenesisBaseFeeChangeDenom = chain.BaseFeeChangeDenom
 )
 
 var (

command/genesis/genesis.go

@@ -249,6 +249,13 @@ func setFlags(cmd *cobra.Command) {
 			defaultBlockTrackerPollInterval,
 			"interval (number of seconds) at which block tracker polls for latest block at rootchain",
 		)
+
+		cmd.Flags().Uint64Var(
+			&params.baseFeeChangeDenom,
+			baseFeeChangeDenomFlag,
+			command.DefaultGenesisBaseFeeChangeDenom,
+			"represents the value to bound the amount the base fee can change between blocks.",
+		)
 	}
 
 	// Access Control Lists

command/genesis/params.go

@@ -42,6 +42,7 @@ const (
 	rewardWalletFlag             = "reward-wallet"
 	blockTrackerPollIntervalFlag = "block-tracker-poll-interval"
 	proxyContractsAdminFlag      = "proxy-contracts-admin"
+	baseFeeChangeDenomFlag       = "base-fee-change-denom"
 
 	defaultNativeTokenName     = "Polygon"
 	defaultNativeTokenSymbol   = "MATIC"
@@ -67,6 +68,7 @@ var (
 	errRewardWalletAmountZero   = errors.New("reward wallet amount can not be zero or negative")
 	errReserveAccMustBePremined = errors.New("it is mandatory to premine reserve account (0x0 address)")
 	errBlockTrackerPollInterval = errors.New("block tracker poll interval must be greater than 0")
+	errBaseFeeChangeDenomZero   = errors.New("base fee change denominator must be greater than 0")
 )
 
 type genesisParams struct {
@@ -138,6 +140,8 @@ type genesisParams struct {
 	blockTrackerPollInterval time.Duration
 
 	proxyContractsAdmin string
+
+	baseFeeChangeDenom uint64
 }
 
 func (p *genesisParams) validateFlags() error {
@@ -157,6 +161,10 @@ func (p *genesisParams) validateFlags() error {
 		return err
 	}
 
+	if p.baseFeeChangeDenom == 0 {
+		return errBaseFeeChangeDenomZero
+	}
+
 	if p.isPolyBFTConsensus() {
 		if err := p.extractNativeTokenMetadata(); err != nil {
 			return err
@@ -409,9 +417,10 @@ func (p *genesisParams) initGenesisConfig() error {
 			GasUsed:    command.DefaultGenesisGasUsed,
 		},
 		Params: &chain.Params{
-			ChainID: int64(p.chainID),
-			Forks:   enabledForks,
-			Engine:  p.consensusEngineConfig,
+			ChainID:            int64(p.chainID),
+			Forks:              enabledForks,
+			Engine:             p.consensusEngineConfig,
+			BaseFeeChangeDenom: p.baseFeeChangeDenom,
 		},
 		Bootnodes: p.bootnodes,
 	}

command/genesis/polybft_params.go

@@ -175,6 +175,7 @@ func (p *genesisParams) generatePolyBftChainConfig(o command.OutputFormatter) er
 			Engine: map[string]interface{}{
 				string(server.PolyBFTConsensus): polyBftConfig,
 			},
+			BaseFeeChangeDenom: p.baseFeeChangeDenom,
 		},
 		Bootnodes: p.bootnodes,
 	}