Add WeightToFee and LengthToFee impls to transaction-payment Runtime API (#13110)

* Add WeightToFee and LengthToFee impls to RPC

* Remove RPC additions

* Update frame/transaction-payment/rpc/runtime-api/src/lib.rs

Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>

* Add comments to length_to_fee and weight_to_fee

Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

substrate/bin/node-template/runtime/src/lib.rs

@@ -477,6 +477,12 @@ impl_runtime_apis! {
 		) -> pallet_transaction_payment::FeeDetails<Balance> {
 			TransactionPayment::query_fee_details(uxt, len)
 		}
+		fn query_weight_to_fee(weight: Weight) -> Balance {
+			TransactionPayment::weight_to_fee(weight)
+		}
+		fn query_length_to_fee(length: u32) -> Balance {
+			TransactionPayment::length_to_fee(length)
+		}
 	}
 
 	impl pallet_transaction_payment_rpc_runtime_api::TransactionPaymentCallApi<Block, Balance, RuntimeCall>
@@ -494,6 +500,12 @@ impl_runtime_apis! {
 		) -> pallet_transaction_payment::FeeDetails<Balance> {
 			TransactionPayment::query_call_fee_details(call, len)
 		}
+		fn query_weight_to_fee(weight: Weight) -> Balance {
+			TransactionPayment::weight_to_fee(weight)
+		}
+		fn query_length_to_fee(length: u32) -> Balance {
+			TransactionPayment::length_to_fee(length)
+		}
 	}
 
 	#[cfg(feature = "runtime-benchmarks")]

substrate/bin/node/runtime/src/lib.rs

@@ -2120,6 +2120,12 @@ impl_runtime_apis! {
 		fn query_fee_details(uxt: <Block as BlockT>::Extrinsic, len: u32) -> FeeDetails<Balance> {
 			TransactionPayment::query_fee_details(uxt, len)
 		}
+		fn query_weight_to_fee(weight: Weight) -> Balance {
+			TransactionPayment::weight_to_fee(weight)
+		}
+		fn query_length_to_fee(length: u32) -> Balance {
+			TransactionPayment::length_to_fee(length)
+		}
 	}
 
 	impl pallet_transaction_payment_rpc_runtime_api::TransactionPaymentCallApi<Block, Balance, RuntimeCall>
@@ -2131,6 +2137,12 @@ impl_runtime_apis! {
 		fn query_call_fee_details(call: RuntimeCall, len: u32) -> FeeDetails<Balance> {
 			TransactionPayment::query_call_fee_details(call, len)
 		}
+		fn query_weight_to_fee(weight: Weight) -> Balance {
+			TransactionPayment::weight_to_fee(weight)
+		}
+		fn query_length_to_fee(length: u32) -> Balance {
+			TransactionPayment::length_to_fee(length)
+		}
 	}
 
 	impl pallet_mmr::primitives::MmrApi<

substrate/frame/transaction-payment/rpc/runtime-api/src/lib.rs

@@ -25,7 +25,7 @@ use sp_runtime::traits::MaybeDisplay;
 pub use pallet_transaction_payment::{FeeDetails, InclusionFee, RuntimeDispatchInfo};
 
 sp_api::decl_runtime_apis! {
-	#[api_version(2)]
+	#[api_version(3)]
 	pub trait TransactionPaymentApi<Balance> where
 		Balance: Codec + MaybeDisplay,
 	{
@@ -33,9 +33,11 @@ sp_api::decl_runtime_apis! {
 		fn query_info(uxt: Block::Extrinsic, len: u32) -> RuntimeDispatchInfo<Balance, sp_weights::OldWeight>;
 		fn query_info(uxt: Block::Extrinsic, len: u32) -> RuntimeDispatchInfo<Balance>;
 		fn query_fee_details(uxt: Block::Extrinsic, len: u32) -> FeeDetails<Balance>;
+		fn query_weight_to_fee(weight: sp_weights::Weight) -> Balance;
+		fn query_length_to_fee(length: u32) -> Balance;
 	}
 
-	#[api_version(2)]
+	#[api_version(3)]
 	pub trait TransactionPaymentCallApi<Balance, Call>
 	where
 		Balance: Codec + MaybeDisplay,
@@ -46,5 +48,11 @@ sp_api::decl_runtime_apis! {
 
 		/// Query fee details of a given encoded `Call`.
 		fn query_call_fee_details(call: Call, len: u32) -> FeeDetails<Balance>;
+
+		/// Query the output of the current `WeightToFee` given some input.
+		fn query_weight_to_fee(weight: sp_weights::Weight) -> Balance;
+
+		/// Query the output of the current `LengthToFee` given some input.
+		fn query_length_to_fee(length: u32) -> Balance;
 	}
 }

substrate/frame/transaction-payment/src/lib.rs

@@ -612,11 +612,14 @@ where
 		}
 	}
 
-	fn length_to_fee(length: u32) -> BalanceOf<T> {
+	/// Compute the length portion of a fee by invoking the configured `LengthToFee` impl.
+	pub fn length_to_fee(length: u32) -> BalanceOf<T> {
 		T::LengthToFee::weight_to_fee(&Weight::from_ref_time(length as u64))
 	}
 
-	fn weight_to_fee(weight: Weight) -> BalanceOf<T> {
+	/// Compute the unadjusted portion of the weight fee by invoking the configured `WeightToFee`
+	/// impl. Note that the input `weight` is capped by the maximum block weight before computation.
+	pub fn weight_to_fee(weight: Weight) -> BalanceOf<T> {
 		// cap the weight to the maximum defined in runtime, otherwise it will be the
 		// `Bounded` maximum of its data type, which is not desired.
 		let capped_weight = weight.min(T::BlockWeights::get().max_block);