Companion of paritytech/cumulus#2326

Author: aurexav

runtime/common/src/lib.rs

@@ -38,8 +38,8 @@ use dc_primitives::*;
 use frame_support::{
 	sp_runtime::Perbill,
 	weights::{
-		constants::ExtrinsicBaseWeight, WeightToFeeCoefficient, WeightToFeeCoefficients,
-		WeightToFeePolynomial,
+		constants::ExtrinsicBaseWeight, Weight, WeightToFee as WeightToFeeT,
+		WeightToFeeCoefficient, WeightToFeeCoefficients, WeightToFeePolynomial,
 	},
 };
 
@@ -64,7 +64,21 @@ macro_rules! fast_runtime_or_not {
 ///   - Setting it to `0` will essentially disable the weight fee.
 ///   - Setting it to `1` will cause the literal `#[weight = x]` values to be charged.
 pub struct WeightToFee;
-impl WeightToFeePolynomial for WeightToFee {
+impl WeightToFeeT for WeightToFee {
+	type Balance = Balance;
+
+	fn weight_to_fee(weight: &Weight) -> Self::Balance {
+		let time_poly: FeePolynomial<Balance> = RefTimeToFee::polynomial().into();
+		let proof_poly: FeePolynomial<Balance> = ProofSizeToFee::polynomial().into();
+
+		// Take the maximum instead of the sum to charge by the more scarce resource.
+		time_poly.eval(weight.ref_time()).max(proof_poly.eval(weight.proof_size()))
+	}
+}
+
+/// Maps the reference time component of `Weight` to a fee.
+pub struct RefTimeToFee;
+impl WeightToFeePolynomial for RefTimeToFee {
 	type Balance = Balance;
 
 	fn polynomial() -> WeightToFeeCoefficients<Self::Balance> {
@@ -80,6 +94,25 @@ impl WeightToFeePolynomial for WeightToFee {
 	}
 }
 
+/// Maps the proof size component of `Weight` to a fee.
+pub struct ProofSizeToFee;
+impl WeightToFeePolynomial for ProofSizeToFee {
+	type Balance = Balance;
+
+	fn polynomial() -> WeightToFeeCoefficients<Self::Balance> {
+		// Map 1MB proof to 1 UNIT.
+		let p = UNIT;
+		let q = 10_000_000;
+
+		smallvec![WeightToFeeCoefficient {
+			degree: 1,
+			negative: false,
+			coeff_frac: Perbill::from_rational(p % q, q),
+			coeff_integer: p / q,
+		}]
+	}
+}
+
 pub struct DealWithFees<R>(sp_std::marker::PhantomData<R>);
 impl<R> frame_support::traits::OnUnbalanced<pallet_balances::NegativeImbalance<R>>
 	for DealWithFees<R>