98 lines
2.7 KiB
Go
98 lines
2.7 KiB
Go
package vm
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import (
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"github.com/filecoin-project/specs-actors/actors/abi"
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"github.com/filecoin-project/specs-actors/actors/abi/big"
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)
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const (
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gasOveruseNum = 11
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gasOveruseDenom = 10
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)
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type GasOutputs struct {
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BaseFeeBurn abi.TokenAmount
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OverEstimationBurn abi.TokenAmount
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MinerPenalty abi.TokenAmount
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MinerTip abi.TokenAmount
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Refund abi.TokenAmount
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GasRefund int64
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GasBurned int64
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}
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// ComputeGasOverestimationBurn computes amount of gas to be refunded and amount of gas to be burned
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// Result is (refund, burn)
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func ComputeGasOverestimationBurn(gasUsed, gasLimit int64) (int64, int64) {
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if gasUsed == 0 {
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return 0, gasLimit
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}
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// over = gasLimit/gasUsed - 1 - 0.1
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// over = min(over, 1)
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// gasToBurn = (gasLimit - gasUsed) * over
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// so to factor out division from `over`
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// over*gasUsed = min(gasLimit - (11*gasUsed)/10, gasUsed)
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// gasToBurn = ((gasLimit - gasUsed)*over*gasUsed) / gasUsed
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over := gasLimit - (gasOveruseNum*gasUsed)/gasOveruseDenom
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if over < 0 {
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return gasLimit - gasUsed, 0
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}
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// if we want sharper scaling it goes here:
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// over *= 2
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if over > gasUsed {
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over = gasUsed
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}
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// needs bigint, as it overflows in pathological case gasLimit > 2^32 gasUsed = gasLimit / 2
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gasToBurn := big.NewInt(gasLimit - gasUsed)
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gasToBurn = big.Mul(gasToBurn, big.NewInt(over))
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gasToBurn = big.Div(gasToBurn, big.NewInt(gasUsed))
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return gasLimit - gasUsed - gasToBurn.Int64(), gasToBurn.Int64()
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}
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func ComputeGasOutputs(gasUsed, gasLimit int64, baseFee, feeCap, gasPremium abi.TokenAmount) GasOutputs {
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gasUsedBig := big.NewInt(gasUsed)
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out := GasOutputs{
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BaseFeeBurn: big.Zero(),
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OverEstimationBurn: big.Zero(),
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MinerPenalty: big.Zero(),
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MinerTip: big.Zero(),
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Refund: big.Zero(),
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}
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baseFeeToPay := baseFee
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if baseFee.Cmp(feeCap.Int) > 0 {
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baseFeeToPay = feeCap
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out.MinerPenalty = big.Mul(big.Sub(baseFee, feeCap), gasUsedBig)
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}
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out.BaseFeeBurn = big.Mul(baseFeeToPay, gasUsedBig)
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minerTip := gasPremium
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if big.Cmp(big.Add(baseFeeToPay, minerTip), feeCap) > 0 {
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minerTip = big.Sub(feeCap, baseFeeToPay)
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}
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out.MinerTip = big.Mul(minerTip, big.NewInt(gasLimit))
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out.GasRefund, out.GasBurned = ComputeGasOverestimationBurn(gasUsed, gasLimit)
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if out.GasBurned != 0 {
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gasBurnedBig := big.NewInt(out.GasBurned)
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out.OverEstimationBurn = big.Mul(baseFeeToPay, gasBurnedBig)
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minerPenalty := big.Mul(big.Sub(baseFee, baseFeeToPay), gasBurnedBig)
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out.MinerPenalty = big.Add(out.MinerPenalty, minerPenalty)
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}
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requiredFunds := big.Mul(big.NewInt(gasLimit), feeCap)
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refund := big.Sub(requiredFunds, out.BaseFeeBurn)
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refund = big.Sub(refund, out.MinerTip)
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refund = big.Sub(refund, out.OverEstimationBurn)
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out.Refund = refund
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return out
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}
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