Introduce WeightToFee trait instead of WeightToFeePolynomial and …

…make `WeightToFeePolynomial` implement it instead (paritytech#11415)

* Introduce `WeightToFee` trait instead of `WeightToFeePolynomial` and make `WeightToFeePolynomial` implement it instead

* Rename `WeightToFee::calc()` to `WeightToFee::wight_to_fee()`

* Fix typo

bin/node/executor/tests/fees.rs

@@ -18,9 +18,7 @@
 use codec::{Encode, Joiner};
 use frame_support::{
 	traits::Currency,
-	weights::{
-		constants::ExtrinsicBaseWeight, GetDispatchInfo, IdentityFee, WeightToFeePolynomial,
-	},
+	weights::{constants::ExtrinsicBaseWeight, GetDispatchInfo, IdentityFee, WeightToFee},
 };
 use node_primitives::Balance;
 use node_runtime::{
@@ -197,13 +195,13 @@ fn transaction_fee_is_correct() {
 		let mut balance_alice = (100 - 69) * DOLLARS;
 
 		let base_weight = ExtrinsicBaseWeight::get();
-		let base_fee = IdentityFee::<Balance>::calc(&base_weight);
+		let base_fee = IdentityFee::<Balance>::weight_to_fee(&base_weight);
 
 		let length_fee = TransactionByteFee::get() * (xt.clone().encode().len() as Balance);
 		balance_alice -= length_fee;
 
 		let weight = default_transfer_call().get_dispatch_info().weight;
-		let weight_fee = IdentityFee::<Balance>::calc(&weight);
+		let weight_fee = IdentityFee::<Balance>::weight_to_fee(&weight);
 
 		// we know that weight to fee multiplier is effect-less in block 1.
 		// current weight of transfer = 200_000_000

bin/node/runtime/src/impls.rs

@@ -59,7 +59,7 @@ mod multiplier_tests {
 		AdjustmentVariable, MinimumMultiplier, Runtime, RuntimeBlockWeights as BlockWeights,
 		System, TargetBlockFullness, TransactionPayment,
 	};
-	use frame_support::weights::{DispatchClass, Weight, WeightToFeePolynomial};
+	use frame_support::weights::{DispatchClass, Weight, WeightToFee};
 
 	fn max_normal() -> Weight {
 		BlockWeights::get()
@@ -234,7 +234,9 @@ mod multiplier_tests {
 				fm = next;
 				iterations += 1;
 				let fee =
-					<Runtime as pallet_transaction_payment::Config>::WeightToFee::calc(&tx_weight);
+					<Runtime as pallet_transaction_payment::Config>::WeightToFee::weight_to_fee(
+						&tx_weight,
+					);
 				let adjusted_fee = fm.saturating_mul_acc_int(fee);
 				println!(
 					"iteration {}, new fm = {:?}. Fee at this point is: {} units / {} millicents, \

frame/executive/src/lib.rs

@@ -576,9 +576,7 @@ mod tests {
 			ConstU32, ConstU64, ConstU8, Currency, LockIdentifier, LockableCurrency,
 			WithdrawReasons,
 		},
-		weights::{
-			ConstantMultiplier, IdentityFee, RuntimeDbWeight, Weight, WeightToFeePolynomial,
-		},
+		weights::{ConstantMultiplier, IdentityFee, RuntimeDbWeight, Weight, WeightToFee},
 	};
 	use frame_system::{Call as SystemCall, ChainContext, LastRuntimeUpgradeInfo};
 	use pallet_balances::Call as BalancesCall;
@@ -866,7 +864,7 @@ mod tests {
 				.get(DispatchClass::Normal)
 				.base_extrinsic;
 		let fee: Balance =
-			<Runtime as pallet_transaction_payment::Config>::WeightToFee::calc(&weight);
+			<Runtime as pallet_transaction_payment::Config>::WeightToFee::weight_to_fee(&weight);
 		let mut t = sp_io::TestExternalities::new(t);
 		t.execute_with(|| {
 			Executive::initialize_block(&Header::new(
@@ -1153,7 +1151,9 @@ mod tests {
 						.get(DispatchClass::Normal)
 						.base_extrinsic;
 				let fee: Balance =
-					<Runtime as pallet_transaction_payment::Config>::WeightToFee::calc(&weight);
+					<Runtime as pallet_transaction_payment::Config>::WeightToFee::weight_to_fee(
+						&weight,
+					);
 				Executive::initialize_block(&Header::new(
 					1,
 					H256::default(),

frame/support/src/weights.rs

@@ -140,7 +140,7 @@ use codec::{Decode, Encode};
 use scale_info::TypeInfo;
 #[cfg(feature = "std")]
 use serde::{Deserialize, Serialize};
-use smallvec::{smallvec, SmallVec};
+use smallvec::SmallVec;
 use sp_arithmetic::{
 	traits::{BaseArithmetic, Saturating, Unsigned},
 	Perbill,
@@ -622,7 +622,7 @@ impl RuntimeDbWeight {
 	}
 }
 
-/// One coefficient and its position in the `WeightToFeePolynomial`.
+/// One coefficient and its position in the `WeightToFee`.
 ///
 /// One term of polynomial is calculated as:
 ///
@@ -647,6 +647,15 @@ pub struct WeightToFeeCoefficient<Balance> {
 /// A list of coefficients that represent one polynomial.
 pub type WeightToFeeCoefficients<T> = SmallVec<[WeightToFeeCoefficient<T>; 4]>;
 
+/// A trait that describes the weight to fee calculation.
+pub trait WeightToFee {
+	/// The type that is returned as result from calculation.
+	type Balance: BaseArithmetic + From<u32> + Copy + Unsigned;
+
+	/// Calculates the fee from the passed `weight`.
+	fn weight_to_fee(weight: &Weight) -> Self::Balance;
+}
+
 /// A trait that describes the weight to fee calculation as polynomial.
 ///
 /// An implementor should only implement the `polynomial` function.
@@ -661,12 +670,19 @@ pub trait WeightToFeePolynomial {
 	/// that the order of coefficients is important as putting the negative coefficients
 	/// first will most likely saturate the result to zero mid evaluation.
 	fn polynomial() -> WeightToFeeCoefficients<Self::Balance>;
+}
+
+impl<T> WeightToFee for T
+where
+	T: WeightToFeePolynomial,
+{
+	type Balance = <Self as WeightToFeePolynomial>::Balance;
 
 	/// Calculates the fee from the passed `weight` according to the `polynomial`.
 	///
 	/// This should not be overriden in most circumstances. Calculation is done in the
 	/// `Balance` type and never overflows. All evaluation is saturating.
-	fn calc(weight: &Weight) -> Self::Balance {
+	fn weight_to_fee(weight: &Weight) -> Self::Balance {
 		Self::polynomial()
 			.iter()
 			.fold(Self::Balance::saturated_from(0u32), |mut acc, args| {
@@ -690,30 +706,21 @@ pub trait WeightToFeePolynomial {
 	}
 }
 
-/// Implementor of `WeightToFeePolynomial` that maps one unit of weight to one unit of fee.
+/// Implementor of `WeightToFee` that maps one unit of weight to one unit of fee.
 pub struct IdentityFee<T>(sp_std::marker::PhantomData<T>);
 
-impl<T> WeightToFeePolynomial for IdentityFee<T>
+impl<T> WeightToFee for IdentityFee<T>
 where
 	T: BaseArithmetic + From<u32> + Copy + Unsigned,
 {
 	type Balance = T;
 
-	fn polynomial() -> WeightToFeeCoefficients<Self::Balance> {
-		smallvec!(WeightToFeeCoefficient {
-			coeff_integer: 1u32.into(),
-			coeff_frac: Perbill::zero(),
-			negative: false,
-			degree: 1,
-		})
-	}
-
-	fn calc(weight: &Weight) -> Self::Balance {
+	fn weight_to_fee(weight: &Weight) -> Self::Balance {
 		Self::Balance::saturated_from(*weight)
 	}
 }
 
-/// Implementor of [`WeightToFeePolynomial`] that uses a constant multiplier.
+/// Implementor of [`WeightToFee`] that uses a constant multiplier.
 /// # Example
 ///
 /// ```
@@ -724,23 +731,14 @@ where
 /// ```
 pub struct ConstantMultiplier<T, M>(sp_std::marker::PhantomData<(T, M)>);
 
-impl<T, M> WeightToFeePolynomial for ConstantMultiplier<T, M>
+impl<T, M> WeightToFee for ConstantMultiplier<T, M>
 where
 	T: BaseArithmetic + From<u32> + Copy + Unsigned,
 	M: Get<T>,
 {
 	type Balance = T;
 
-	fn polynomial() -> WeightToFeeCoefficients<Self::Balance> {
-		smallvec!(WeightToFeeCoefficient {
-			coeff_integer: M::get(),
-			coeff_frac: Perbill::zero(),
-			negative: false,
-			degree: 1,
-		})
-	}
-
-	fn calc(weight: &Weight) -> Self::Balance {
+	fn weight_to_fee(weight: &Weight) -> Self::Balance {
 		Self::Balance::saturated_from(*weight).saturating_mul(M::get())
 	}
 }
@@ -831,6 +829,7 @@ impl PerDispatchClass<Weight> {
 mod tests {
 	use super::*;
 	use crate::{decl_module, parameter_types, traits::Get};
+	use smallvec::smallvec;
 
 	pub trait Config: 'static {
 		type Origin;
@@ -997,35 +996,41 @@ mod tests {
 	#[test]
 	fn polynomial_works() {
 		// 100^3/2=500000 100^2*(2+1/3)=23333 700 -10000
-		assert_eq!(Poly::calc(&100), 514033);
+		assert_eq!(Poly::weight_to_fee(&100), 514033);
 		// 10123^3/2=518677865433 10123^2*(2+1/3)=239108634 70861 -10000
-		assert_eq!(Poly::calc(&10_123), 518917034928);
+		assert_eq!(Poly::weight_to_fee(&10_123), 518917034928);
 	}
 
 	#[test]
 	fn polynomial_does_not_underflow() {
-		assert_eq!(Poly::calc(&0), 0);
-		assert_eq!(Poly::calc(&10), 0);
+		assert_eq!(Poly::weight_to_fee(&0), 0);
+		assert_eq!(Poly::weight_to_fee(&10), 0);
 	}
 
 	#[test]
 	fn polynomial_does_not_overflow() {
-		assert_eq!(Poly::calc(&Weight::max_value()), Balance::max_value() - 10_000);
+		assert_eq!(Poly::weight_to_fee(&Weight::max_value()), Balance::max_value() - 10_000);
 	}
 
 	#[test]
 	fn identity_fee_works() {
-		assert_eq!(IdentityFee::<Balance>::calc(&0), 0);
-		assert_eq!(IdentityFee::<Balance>::calc(&50), 50);
-		assert_eq!(IdentityFee::<Balance>::calc(&Weight::max_value()), Balance::max_value());
+		assert_eq!(IdentityFee::<Balance>::weight_to_fee(&0), 0);
+		assert_eq!(IdentityFee::<Balance>::weight_to_fee(&50), 50);
+		assert_eq!(
+			IdentityFee::<Balance>::weight_to_fee(&Weight::max_value()),
+			Balance::max_value()
+		);
 	}
 
 	#[test]
 	fn constant_fee_works() {
 		use crate::traits::ConstU128;
-		assert_eq!(ConstantMultiplier::<u128, ConstU128<100u128>>::calc(&0), 0);
-		assert_eq!(ConstantMultiplier::<u128, ConstU128<10u128>>::calc(&50), 500);
-		assert_eq!(ConstantMultiplier::<u128, ConstU128<1024u128>>::calc(&16), 16384);
-		assert_eq!(ConstantMultiplier::<u128, ConstU128<{ u128::MAX }>>::calc(&2), u128::MAX);
+		assert_eq!(ConstantMultiplier::<u128, ConstU128<100u128>>::weight_to_fee(&0), 0);
+		assert_eq!(ConstantMultiplier::<u128, ConstU128<10u128>>::weight_to_fee(&50), 500);
+		assert_eq!(ConstantMultiplier::<u128, ConstU128<1024u128>>::weight_to_fee(&16), 16384);
+		assert_eq!(
+			ConstantMultiplier::<u128, ConstU128<{ u128::MAX }>>::weight_to_fee(&2),
+			u128::MAX
+		);
 	}
 }

frame/transaction-payment/Cargo.toml

@@ -18,7 +18,6 @@ codec = { package = "parity-scale-codec", version = "3.0.0", default-features =
 ] }
 scale-info = { version = "2.1.1", default-features = false, features = ["derive"] }
 serde = { version = "1.0.136", optional = true }
-smallvec = "1.8.0"
 frame-support = { version = "4.0.0-dev", default-features = false, path = "../support" }
 frame-system = { version = "4.0.0-dev", default-features = false, path = "../system" }
 sp-core = { version = "6.0.0", default-features = false, path = "../../primitives/core" }

frame/transaction-payment/asset-tx-payment/Cargo.toml

@@ -29,7 +29,6 @@ scale-info = { version = "2.1.1", default-features = false, features = ["derive"
 serde = { version = "1.0.136", optional = true }
 
 [dev-dependencies]
-smallvec = "1.8.0"
 serde_json = "1.0.79"
 
 sp-storage = { version = "6.0.0", default-features = false, path = "../../../primitives/storage" }

frame/transaction-payment/asset-tx-payment/src/tests.rs

@@ -21,22 +21,17 @@ use frame_support::{
 	pallet_prelude::*,
 	parameter_types,
 	traits::{fungibles::Mutate, ConstU32, ConstU64, ConstU8, FindAuthor},
-	weights::{
-		DispatchClass, DispatchInfo, PostDispatchInfo, Weight, WeightToFeeCoefficient,
-		WeightToFeeCoefficients, WeightToFeePolynomial,
-	},
+	weights::{DispatchClass, DispatchInfo, PostDispatchInfo, Weight, WeightToFee as WeightToFeeT},
 	ConsensusEngineId,
 };
 use frame_system as system;
 use frame_system::EnsureRoot;
 use pallet_balances::Call as BalancesCall;
 use pallet_transaction_payment::CurrencyAdapter;
-use smallvec::smallvec;
 use sp_core::H256;
 use sp_runtime::{
 	testing::Header,
-	traits::{BlakeTwo256, ConvertInto, IdentityLookup, StaticLookup},
-	Perbill,
+	traits::{BlakeTwo256, ConvertInto, IdentityLookup, SaturatedConversion, StaticLookup},
 };
 use std::cell::RefCell;
 
@@ -83,8 +78,8 @@ impl Get<frame_system::limits::BlockWeights> for BlockWeights {
 }
 
 parameter_types! {
-	pub static TransactionByteFee: u64 = 1;
 	pub static WeightToFee: u64 = 1;
+	pub static TransactionByteFee: u64 = 1;
 }
 
 impl frame_system::Config for Runtime {
@@ -130,23 +125,27 @@ impl pallet_balances::Config for Runtime {
 	type ReserveIdentifier = [u8; 8];
 }
 
-impl WeightToFeePolynomial for WeightToFee {
+impl WeightToFeeT for WeightToFee {
+	type Balance = u64;
+
+	fn weight_to_fee(weight: &Weight) -> Self::Balance {
+		Self::Balance::saturated_from(*weight).saturating_mul(WEIGHT_TO_FEE.with(|v| *v.borrow()))
+	}
+}
+
+impl WeightToFeeT for TransactionByteFee {
 	type Balance = u64;
 
-	fn polynomial() -> WeightToFeeCoefficients<Self::Balance> {
-		smallvec![WeightToFeeCoefficient {
-			degree: 1,
-			coeff_frac: Perbill::zero(),
-			coeff_integer: WEIGHT_TO_FEE.with(|v| *v.borrow()),
-			negative: false,
-		}]
+	fn weight_to_fee(weight: &Weight) -> Self::Balance {
+		Self::Balance::saturated_from(*weight)
+			.saturating_mul(TRANSACTION_BYTE_FEE.with(|v| *v.borrow()))
 	}
 }
 
 impl pallet_transaction_payment::Config for Runtime {
 	type OnChargeTransaction = CurrencyAdapter<Balances, ()>;
 	type WeightToFee = WeightToFee;
-	type LengthToFee = WeightToFee;
+	type LengthToFee = TransactionByteFee;
 	type FeeMultiplierUpdate = ();
 	type OperationalFeeMultiplier = ConstU8<5>;
 }