Problem: ibc relayer don't work well with default tx prioritization strategy

CHANGELOG.md

@@ -10,6 +10,7 @@
 
 - Upgrade `cosmos-sdk` to `v0.45.6` and `ibc-go` to `v4.0.0-rc0`. #803
 - Changed go version to `1.18`. #803
+- Change the default priority mechanism to be based on gas price
 
 ### Security
 

app/app.go

@@ -643,6 +643,7 @@ func New(
 				FeegrantKeeper:  app.FeeGrantKeeper,
 				SignModeHandler: encodingConfig.TxConfig.SignModeHandler(),
 				SigGasConsumer:  ante.DefaultSigVerificationGasConsumer,
+				TxFeeChecker:    checkTxFeeWithValidatorMinGasPrices,
 			},
 			IBCKeeper: app.IBCKeeper,
 		},

app/validator_tx_fee.go

@@ -0,0 +1,62 @@
+package app
+
+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).
+			for i, gp := range minGasPrices {
+				fee := gp.Amount.MulInt64(int64(gas))
+				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, int64(gas))
+	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, gas int64) int64 {
+	var priority int64
+	for _, c := range fee {
+		p := int64(math.MaxInt64)
+		gasPrice := c.Amount.QuoRaw(gas)
+		if gasPrice.IsInt64() {
+			p = gasPrice.Int64()
+		}
+		if priority == 0 || p < priority {
+			priority = p
+		}
+	}
+
+	return priority
+}