Refund extra tip (#1706)

* refund extra tip

* add more tests

modules/transaction-payment/src/lib.rs

@@ -884,7 +884,19 @@ where
 		let (tip, who, imbalance, fee) = pre;
 		if let Some(payed) = imbalance {
 			let actual_fee = Pallet::<T>::compute_actual_fee(len as u32, info, post_info, tip);
-			let refund = fee.saturating_sub(actual_fee);
+			let refund_fee = fee.saturating_sub(actual_fee);
+			let mut refund = refund_fee;
+			let mut actual_tip = tip;
+
+			if !tip.is_zero() && !info.weight.is_zero() {
+				// tip_pre_weight * unspent_weight
+				let refund_tip = tip
+					.checked_div(&info.weight.saturated_into::<PalletBalanceOf<T>>())
+					.expect("checked is non-zero; qed")
+					.saturating_mul(post_info.calc_unspent(info).saturated_into::<PalletBalanceOf<T>>());
+				refund = refund_fee.saturating_add(refund_tip);
+				actual_tip = tip.saturating_sub(refund_tip);
+			}
 			let actual_payment = match <T as Config>::Currency::deposit_into_existing(&who, refund) {
 				Ok(refund_imbalance) => {
 					// The refund cannot be larger than the up front payed max weight.
@@ -899,7 +911,7 @@ where
 				// is gone in that case.
 				Err(_) => payed,
 			};
-			let (tip, fee) = actual_payment.split(tip);
+			let (tip, fee) = actual_payment.split(actual_tip);
 
 			// distribute fee
 			<T as Config>::OnTransactionPayment::on_unbalanceds(Some(fee).into_iter().chain(Some(tip)));

modules/transaction-payment/src/tests.rs

@@ -192,6 +192,65 @@ fn refund_fee_according_to_actual_when_post_dispatch_and_native_currency_is_enou
 		});
 }
 
+#[test]
+fn refund_tip_according_to_actual_when_post_dispatch_and_native_currency_is_enough() {
+	ExtBuilder::default()
+		.one_hundred_thousand_for_alice_n_charlie()
+		.build()
+		.execute_with(|| {
+			// tip = 0
+			let fee = 23 * 2 + 1000; // len * byte + weight
+			let pre = ChargeTransactionPayment::<Runtime>::from(0)
+				.pre_dispatch(&ALICE, CALL, &INFO, 23)
+				.unwrap();
+			assert_eq!(Currencies::free_balance(ACA, &ALICE), 100000 - fee);
+
+			let refund = 200; // 1000 - 800
+			assert!(ChargeTransactionPayment::<Runtime>::post_dispatch(pre, &INFO, &POST_INFO, 23, &Ok(())).is_ok());
+			assert_eq!(Currencies::free_balance(ACA, &ALICE), 100000 - fee + refund);
+
+			// tip = 1000
+			let fee = 23 * 2 + 1000; // len * byte + weight
+			let tip = 1000;
+			let pre = ChargeTransactionPayment::<Runtime>::from(tip)
+				.pre_dispatch(&CHARLIE, CALL, &INFO, 23)
+				.unwrap();
+			assert_eq!(Currencies::free_balance(ACA, &CHARLIE), 100000 - fee - tip);
+
+			let refund_fee = 200; // 1000 - 800
+			let refund_tip = 200; // 1000 - 800
+			assert!(ChargeTransactionPayment::<Runtime>::post_dispatch(pre, &INFO, &POST_INFO, 23, &Ok(())).is_ok());
+			assert_eq!(
+				Currencies::free_balance(ACA, &CHARLIE),
+				100000 - fee - tip + refund_fee + refund_tip
+			);
+		});
+}
+
+#[test]
+fn refund_should_not_works() {
+	ExtBuilder::default()
+		.one_hundred_thousand_for_alice_n_charlie()
+		.build()
+		.execute_with(|| {
+			let tip = 1000;
+			let fee = 23 * 2 + 1000; // len * byte + weight
+			let pre = ChargeTransactionPayment::<Runtime>::from(tip)
+				.pre_dispatch(&ALICE, CALL, &INFO, 23)
+				.unwrap();
+			assert_eq!(Currencies::free_balance(ACA, &ALICE), 100000 - fee - tip);
+
+			// actual_weight > weight
+			const POST_INFO: PostDispatchInfo = PostDispatchInfo {
+				actual_weight: Some(INFO.weight + 1),
+				pays_fee: Pays::Yes,
+			};
+
+			assert!(ChargeTransactionPayment::<Runtime>::post_dispatch(pre, &INFO, &POST_INFO, 23, &Ok(())).is_ok());
+			assert_eq!(Currencies::free_balance(ACA, &ALICE), 100000 - fee - tip);
+		});
+}
+
 #[test]
 fn charges_fee_when_validate_and_native_is_not_enough() {
 	ExtBuilder::default()

runtime/acala/src/constants.rs

@@ -49,10 +49,7 @@ pub mod fee {
 	use smallvec::smallvec;
 	use sp_runtime::Perbill;
 
-	/// The block saturation level. Fees will be updates based on this value.
-	pub const TARGET_BLOCK_FULLNESS: Perbill = Perbill::from_percent(25);
-
-	fn base_tx_in_aca() -> Balance {
+	pub fn base_tx_in_aca() -> Balance {
 		cent(ACA) / 10
 	}
 
@@ -71,7 +68,7 @@ pub mod fee {
 	impl WeightToFeePolynomial for WeightToFee {
 		type Balance = Balance;
 		fn polynomial() -> WeightToFeeCoefficients<Self::Balance> {
-			// in Karura, extrinsic base weight (smallest non-zero weight) is mapped to 1/10 CENT:
+			// in Acala, extrinsic base weight (smallest non-zero weight) is mapped to 1/10 CENT:
 			let p = base_tx_in_aca();
 			let q = Balance::from(ExtrinsicBaseWeight::get());
 			smallvec![WeightToFeeCoefficient {
@@ -94,3 +91,19 @@ pub mod fee {
 		aca_per_second() / 50 * dollar(DOT) / dollar(ACA)
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use crate::{constants::fee::base_tx_in_aca, Balance};
+	use frame_support::weights::constants::ExtrinsicBaseWeight;
+
+	#[test]
+	fn check_weight() {
+		let p = base_tx_in_aca();
+		let q = Balance::from(ExtrinsicBaseWeight::get());
+
+		assert_eq!(p, 1_000_000_000);
+		assert_eq!(q, 125_000_000);
+		assert_eq!(p / q, 8);
+	}
+}

runtime/karura/src/constants.rs

@@ -49,10 +49,7 @@ pub mod fee {
 	use smallvec::smallvec;
 	use sp_runtime::Perbill;
 
-	/// The block saturation level. Fees will be updates based on this value.
-	pub const TARGET_BLOCK_FULLNESS: Perbill = Perbill::from_percent(25);
-
-	fn base_tx_in_kar() -> Balance {
+	pub fn base_tx_in_kar() -> Balance {
 		cent(KAR) / 10
 	}
 
@@ -111,3 +108,19 @@ pub mod parachains {
 		pub const KINT_KEY: &[u8] = &[5];
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use crate::{constants::fee::base_tx_in_kar, Balance};
+	use frame_support::weights::constants::ExtrinsicBaseWeight;
+
+	#[test]
+	fn check_weight() {
+		let p = base_tx_in_kar();
+		let q = Balance::from(ExtrinsicBaseWeight::get());
+
+		assert_eq!(p, 1_000_000_000);
+		assert_eq!(q, 125_000_000);
+		assert_eq!(p / q, 8);
+	}
+}

runtime/mandala/src/constants.rs

@@ -49,10 +49,7 @@ pub mod fee {
 	use smallvec::smallvec;
 	use sp_runtime::Perbill;
 
-	/// The block saturation level. Fees will be updates based on this value.
-	pub const TARGET_BLOCK_FULLNESS: Perbill = Perbill::from_percent(25);
-
-	fn base_tx_in_aca() -> Balance {
+	pub fn base_tx_in_aca() -> Balance {
 		cent(ACA) / 10
 	}
 
@@ -71,15 +68,14 @@ pub mod fee {
 	impl WeightToFeePolynomial for WeightToFee {
 		type Balance = Balance;
 		fn polynomial() -> WeightToFeeCoefficients<Self::Balance> {
-			// in Acala, extrinsic base weight (smallest non-zero weight) is mapped to 1/10
-			// CENT:
-			let p = base_tx_in_aca(); // 10_000_000_000;
+			// in Acala, extrinsic base weight (smallest non-zero weight) is mapped to 1/10 CENT:
+			let p = base_tx_in_aca(); // 1_000_000_000;
 			let q = Balance::from(ExtrinsicBaseWeight::get()); // 125_000_000
 			smallvec![WeightToFeeCoefficient {
 				degree: 1,
 				negative: false,
 				coeff_frac: Perbill::from_rational(p % q, q), // zero
-				coeff_integer: p / q,                         // 80
+				coeff_integer: p / q,                         // 8
 			}]
 		}
 	}
@@ -94,3 +90,19 @@ pub mod fee {
 		aca_per_second() / 100
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use crate::{constants::fee::base_tx_in_aca, Balance};
+	use frame_support::weights::constants::ExtrinsicBaseWeight;
+
+	#[test]
+	fn check_weight() {
+		let p = base_tx_in_aca();
+		let q = Balance::from(ExtrinsicBaseWeight::get());
+
+		assert_eq!(p, 1_000_000_000);
+		assert_eq!(q, 125_000_000);
+		assert_eq!(p / q, 8);
+	}
+}

runtime/mandala/src/lib.rs

@@ -40,7 +40,7 @@ pub use frame_support::{
 		Randomness, SortedMembers, U128CurrencyToVote, WithdrawReasons,
 	},
 	weights::{
-		constants::{BlockExecutionWeight, ExtrinsicBaseWeight, RocksDbWeight, WEIGHT_PER_SECOND},
+		constants::{BlockExecutionWeight, RocksDbWeight, WEIGHT_PER_SECOND},
 		DispatchClass, IdentityFee, Weight,
 	},
 	PalletId, RuntimeDebug, StorageValue,