cosmos-sdk/x/auth/ante/validator_tx_fee.go

package ante

import (
	"math"

	sdk "github.com/cosmos/cosmos-sdk/types"
	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
)

// checkTxFeeWithValidatorMinGasPrices implements the default fee logic, where the minimum price per
// unit of gas is fixed and set by each validator, can the tx priority is computed from the gas price.
func checkTxFeeWithValidatorMinGasPrices(ctx sdk.Context, tx sdk.Tx) (sdk.Coins, int64, error) {
	feeTx, ok := tx.(sdk.FeeTx)
	if !ok {
		return nil, 0, sdkerrors.Wrap(sdkerrors.ErrTxDecode, "Tx must be a FeeTx")
	}

	feeCoins := feeTx.GetFee()
	gas := feeTx.GetGas()

	// Ensure that the provided fees meet a minimum threshold for the validator,
	// if this is a CheckTx. This is only for local mempool purposes, and thus
	// is only ran on check tx.
	if ctx.IsCheckTx() {
		minGasPrices := ctx.MinGasPrices()
		if !minGasPrices.IsZero() {
			requiredFees := make(sdk.Coins, len(minGasPrices))

			// Determine the required fees by multiplying each required minimum gas
			// price by the gas limit, where fee = ceil(minGasPrice * gasLimit).
			glDec := sdk.NewDec(int64(gas))
			for i, gp := range minGasPrices {
				fee := gp.Amount.Mul(glDec)
				requiredFees[i] = sdk.NewCoin(gp.Denom, fee.Ceil().RoundInt())
			}

			if !feeCoins.IsAnyGTE(requiredFees) {
				return nil, 0, sdkerrors.Wrapf(sdkerrors.ErrInsufficientFee, "insufficient fees; got: %s required: %s", feeCoins, requiredFees)
			}
		}
	}

	priority := getTxPriority(feeCoins)
	return feeCoins, priority, nil
}

// getTxPriority returns a naive tx priority based on the amount of the smallest denomination of the fee
// provided in a transaction.
func getTxPriority(fee sdk.Coins) int64 {
	var priority int64
	for _, c := range fee {
		p := int64(math.MaxInt64)
		if c.Amount.IsInt64() {
			p = c.Amount.Int64()
		}
		if priority == 0 || p < priority {
			priority = p
		}
	}

	return priority
}