laconicd/x/feemarket/keeper/eip1559.go

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package keeper
import (
"math/big"
sdk "github.com/cosmos/cosmos-sdk/types"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/math"
)
// CalculateBaseFee calculates the base fee for the current block. This is only calculated once per
// block during EndBlock. If the NoBaseFee parameter is enabled or below activation height, this function returns nil.
// NOTE: This code is inspired from the go-ethereum EIP1559 implementation and adapted to Cosmos SDK-based
// chains. For the canonical code refer to: https://github.com/ethereum/go-ethereum/blob/master/consensus/misc/eip1559.go
func (k Keeper) CalculateBaseFee(ctx sdk.Context) *big.Int {
params := k.GetParams(ctx)
// Ignore the calculation if not enable
if !params.IsBaseFeeEnabled(ctx.BlockHeight()) {
return nil
}
consParams := ctx.ConsensusParams()
// If the current block is the first EIP-1559 block, return the InitialBaseFee.
if ctx.BlockHeight() == params.EnableHeight {
return new(big.Int).SetInt64(params.InitialBaseFee)
}
// get the block gas used and the base fee values for the parent block.
parentBaseFee := k.GetBaseFee(ctx)
if parentBaseFee == nil {
parentBaseFee = new(big.Int).SetInt64(params.InitialBaseFee)
}
parentGasUsed := k.GetBlockGasUsed(ctx)
gasLimit := new(big.Int).SetUint64(math.MaxUint64)
if consParams != nil && consParams.Block.MaxGas > -1 {
gasLimit = big.NewInt(consParams.Block.MaxGas)
}
parentGasTargetBig := new(big.Int).Div(gasLimit, new(big.Int).SetUint64(uint64(params.ElasticityMultiplier)))
if !parentGasTargetBig.IsUint64() {
return new(big.Int).SetInt64(params.InitialBaseFee)
}
parentGasTarget := parentGasTargetBig.Uint64()
baseFeeChangeDenominator := new(big.Int).SetUint64(uint64(params.BaseFeeChangeDenominator))
// If the parent gasUsed is the same as the target, the baseFee remains unchanged.
if parentGasUsed == parentGasTarget {
return new(big.Int).Set(parentBaseFee)
}
if parentGasUsed > parentGasTarget {
// If the parent block used more gas than its target, the baseFee should increase.
gasUsedDelta := new(big.Int).SetUint64(parentGasUsed - parentGasTarget)
x := new(big.Int).Mul(parentBaseFee, gasUsedDelta)
y := x.Div(x, parentGasTargetBig)
baseFeeDelta := math.BigMax(
x.Div(y, baseFeeChangeDenominator),
common.Big1,
)
return x.Add(parentBaseFee, baseFeeDelta)
}
// Otherwise if the parent block used less gas than its target, the baseFee should decrease.
gasUsedDelta := new(big.Int).SetUint64(parentGasTarget - parentGasUsed)
x := new(big.Int).Mul(parentBaseFee, gasUsedDelta)
y := x.Div(x, parentGasTargetBig)
baseFeeDelta := x.Div(y, baseFeeChangeDenominator)
return math.BigMax(
x.Sub(parentBaseFee, baseFeeDelta),
common.Big0,
)
}