feat: Change the default priority mechanism to be based on gas price

CHANGELOG.md

@@ -64,6 +64,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [#12693](https://github.com/cosmos/cosmos-sdk/pull/12693) Make sure the order of each node is consistent when emitting proto events.
 * [#12455](https://github.com/cosmos/cosmos-sdk/pull/12455) Show attempts count in error for signing. 
 * [#12886](https://github.com/cosmos/cosmos-sdk/pull/12886) Amortize cost of processing cache KV store
+* [#12953](https://github.com/cosmos/cosmos-sdk/pull/12953) Change the default priority mechanism to be based on gas price.
 
 ### State Machine Breaking
 

x/auth/ante/fee_test.go

@@ -59,7 +59,7 @@ func TestEnsureMempoolFees(t *testing.T) {
 	// msg and signatures
 	msg := testdata.NewTestMsg(accs[0].acc.GetAddress())
 	feeAmount := testdata.NewTestFeeAmount()
-	gasLimit := testdata.NewTestGasLimit()
+	gasLimit := uint64(15)
 	require.NoError(t, s.txBuilder.SetMsgs(msg))
 	s.txBuilder.SetFeeAmount(feeAmount)
 	s.txBuilder.SetGasLimit(gasLimit)
@@ -71,7 +71,7 @@ func TestEnsureMempoolFees(t *testing.T) {
 	require.NoError(t, err)
 
 	// Set high gas price so standard test fee fails
-	atomPrice := sdk.NewDecCoinFromDec("atom", math.LegacyNewDec(200).Quo(math.LegacyNewDec(100000)))
+	atomPrice := sdk.NewDecCoinFromDec("atom", math.LegacyNewDec(20))
 	highGasPrice := []sdk.DecCoin{atomPrice}
 	s.ctx = s.ctx.WithMinGasPrices(highGasPrice)
 
@@ -103,9 +103,9 @@ func TestEnsureMempoolFees(t *testing.T) {
 
 	newCtx, err := antehandler(s.ctx, tx, false)
 	require.Nil(t, err, "Decorator should not have errored on fee higher than local gasPrice")
-	// Priority is the smallest amount in any denom. Since we have only 1 fee
-	// of 150atom, the priority here is 150.
-	require.Equal(t, feeAmount.AmountOf("atom").Int64(), newCtx.Priority())
+	// Priority is the smallest gas price amount in any denom. Since we have only 1 gas price
+	// of 10atom, the priority here is 10.
+	require.Equal(t, int64(10), newCtx.Priority())
 }
 
 func TestDeductFees(t *testing.T) {

x/auth/ante/validator_tx_fee.go

@@ -41,18 +41,21 @@ func checkTxFeeWithValidatorMinGasPrices(ctx sdk.Context, tx sdk.Tx) (sdk.Coins,
 		}
 	}
 
-	priority := getTxPriority(feeCoins)
+	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
+// getTxPriority returns a naive tx priority based on the amount of the smallest denomination of the gas price
 // provided in a transaction.
-func getTxPriority(fee sdk.Coins) int64 {
+// NOTE: This implementation should be used with a great consideration as it opens potential attack vectors
+// where txs with multiple coins could not be prioritize as expected.
+func getTxPriority(fee sdk.Coins, gas int64) int64 {
 	var priority int64
 	for _, c := range fee {
 		p := int64(math.MaxInt64)
-		if c.Amount.IsInt64() {
-			p = c.Amount.Int64()
+		gasPrice := c.Amount.QuoRaw(gas)
+		if gasPrice.IsInt64() {
+			p = gasPrice.Int64()
 		}
 		if priority == 0 || p < priority {
 			priority = p