payment_queryInfo: Make it work with WeightV2 (paritytech#12633)

* `payment_queryInfo`: Make it work with `WeighV2`

The runtime api for querying the payment info depends on the `Weight` type and broke for old
runtimes that still use the `WeighV1`. This pull requests fixes this by:

1. Bumping the version of the runtime api.
2. Making the node side code use the correct runtime api function depending on the version of the
runtime api.
3. Make the RPC always return `WeighV1`.

Users of the api should switch to `state_call` and decide based on the version of the runtime api
which `Weight` type is being returned.

* Fix tests

* Review comment

frame/transaction-payment/rpc/Cargo.toml

@@ -21,3 +21,4 @@ sp-blockchain = { version = "4.0.0-dev", path = "../../../primitives/blockchain"
 sp-core = { version = "6.0.0", path = "../../../primitives/core" }
 sp-rpc = { version = "6.0.0", path = "../../../primitives/rpc" }
 sp-runtime = { version = "6.0.0", path = "../../../primitives/runtime" }
+sp-weights = { version = "4.0.0", path = "../../../primitives/weights" }

frame/transaction-payment/rpc/runtime-api/Cargo.toml

@@ -17,6 +17,7 @@ codec = { package = "parity-scale-codec", version = "3.0.0", default-features =
 pallet-transaction-payment = { version = "4.0.0-dev", default-features = false, path = "../../../transaction-payment" }
 sp-api = { version = "4.0.0-dev", default-features = false, path = "../../../../primitives/api" }
 sp-runtime = { version = "6.0.0", default-features = false, path = "../../../../primitives/runtime" }
+sp-weights = { version = "4.0.0", default-features = false, path = "../../../../primitives/weights" }
 
 [features]
 default = ["std"]
@@ -25,4 +26,5 @@ std = [
 	"pallet-transaction-payment/std",
 	"sp-api/std",
 	"sp-runtime/std",
+	"sp-weights/std",
 ]

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

@@ -25,13 +25,17 @@ use sp_runtime::traits::MaybeDisplay;
 pub use pallet_transaction_payment::{FeeDetails, InclusionFee, RuntimeDispatchInfo};
 
 sp_api::decl_runtime_apis! {
+	#[api_version(2)]
 	pub trait TransactionPaymentApi<Balance> where
 		Balance: Codec + MaybeDisplay,
 	{
+		#[changed_in(2)]
+		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>;
 	}
 
+	#[api_version(2)]
 	pub trait TransactionPaymentCallApi<Balance, Call>
 	where
 		Balance: Codec + MaybeDisplay,

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

@@ -26,7 +26,7 @@ use jsonrpsee::{
 	types::error::{CallError, ErrorCode, ErrorObject},
 };
 use pallet_transaction_payment_rpc_runtime_api::{FeeDetails, InclusionFee, RuntimeDispatchInfo};
-use sp_api::ProvideRuntimeApi;
+use sp_api::{ApiExt, ProvideRuntimeApi};
 use sp_blockchain::HeaderBackend;
 use sp_core::Bytes;
 use sp_rpc::number::NumberOrHex;
@@ -82,8 +82,10 @@ impl From<Error> for i32 {
 }
 
 impl<C, Block, Balance>
-	TransactionPaymentApiServer<<Block as BlockT>::Hash, RuntimeDispatchInfo<Balance>>
-	for TransactionPayment<C, Block>
+	TransactionPaymentApiServer<
+		<Block as BlockT>::Hash,
+		RuntimeDispatchInfo<Balance, sp_weights::OldWeight>,
+	> for TransactionPayment<C, Block>
 where
 	Block: BlockT,
 	C: ProvideRuntimeApi<Block> + HeaderBackend<Block> + Send + Sync + 'static,
@@ -94,7 +96,7 @@ where
 		&self,
 		encoded_xt: Bytes,
 		at: Option<Block::Hash>,
-	) -> RpcResult<RuntimeDispatchInfo<Balance>> {
+	) -> RpcResult<RuntimeDispatchInfo<Balance, sp_weights::OldWeight>> {
 		let api = self.client.runtime_api();
 		let at = BlockId::hash(at.unwrap_or_else(|| self.client.info().best_hash));
 
@@ -107,14 +109,41 @@ where
 				Some(format!("{:?}", e)),
 			))
 		})?;
-		api.query_info(&at, uxt, encoded_len).map_err(|e| {
+
+		fn map_err(error: impl ToString, desc: &'static str) -> CallError {
 			CallError::Custom(ErrorObject::owned(
 				Error::RuntimeError.into(),
-				"Unable to query dispatch info.",
-				Some(e.to_string()),
+				desc,
+				Some(error.to_string()),
 			))
-			.into()
-		})
+		}
+
+		let api_version = api
+			.api_version::<dyn TransactionPaymentRuntimeApi<Block, Balance>>(&at)
+			.map_err(|e| map_err(e, "Failed to get transaction payment runtime api version"))?
+			.ok_or_else(|| {
+				CallError::Custom(ErrorObject::owned(
+					Error::RuntimeError.into(),
+					"Transaction payment runtime api wasn't found in the runtime",
+					None::<String>,
+				))
+			})?;
+
+		if api_version < 2 {
+			#[allow(deprecated)]
+			api.query_info_before_version_2(&at, uxt, encoded_len)
+				.map_err(|e| map_err(e, "Unable to query dispatch info.").into())
+		} else {
+			let res = api
+				.query_info(&at, uxt, encoded_len)
+				.map_err(|e| map_err(e, "Unable to query dispatch info."))?;
+
+			Ok(RuntimeDispatchInfo {
+				weight: sp_weights::OldWeight(res.weight.ref_time()),
+				class: res.class,
+				partial_fee: res.partial_fee,
+			})
+		}
 	}
 
 	fn query_fee_details(

frame/transaction-payment/src/types.rs

@@ -24,7 +24,7 @@ use serde::{Deserialize, Serialize};
 use sp_runtime::traits::{AtLeast32BitUnsigned, Zero};
 use sp_std::prelude::*;
 
-use frame_support::{dispatch::DispatchClass, weights::Weight};
+use frame_support::dispatch::DispatchClass;
 
 /// The base fee and adjusted weight and length fees constitute the _inclusion fee_.
 #[derive(Encode, Decode, Clone, Eq, PartialEq)]
@@ -94,9 +94,15 @@ impl<Balance: AtLeast32BitUnsigned + Copy> FeeDetails<Balance> {
 #[derive(Eq, PartialEq, Encode, Decode, Default)]
 #[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
 #[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
-#[cfg_attr(feature = "std", serde(bound(serialize = "Balance: std::fmt::Display")))]
-#[cfg_attr(feature = "std", serde(bound(deserialize = "Balance: std::str::FromStr")))]
-pub struct RuntimeDispatchInfo<Balance> {
+#[cfg_attr(
+	feature = "std",
+	serde(bound(serialize = "Balance: std::fmt::Display, Weight: Serialize"))
+)]
+#[cfg_attr(
+	feature = "std",
+	serde(bound(deserialize = "Balance: std::str::FromStr, Weight: Deserialize<'de>"))
+)]
+pub struct RuntimeDispatchInfo<Balance, Weight = frame_support::weights::Weight> {
 	/// Weight of this dispatch.
 	pub weight: Weight,
 	/// Class of this dispatch.
@@ -131,6 +137,7 @@ mod serde_balance {
 #[cfg(test)]
 mod tests {
 	use super::*;
+	use frame_support::weights::Weight;
 
 	#[test]
 	fn should_serialize_and_deserialize_properly_with_string() {

primitives/weights/src/lib.rs

@@ -26,8 +26,6 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
-extern crate self as sp_weights;
-
 mod weight_v2;
 
 use codec::{CompactAs, Decode, Encode, MaxEncodedLen};
@@ -70,6 +68,8 @@ pub mod constants {
 	MaxEncodedLen,
 	TypeInfo,
 )]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "std", serde(transparent))]
 pub struct OldWeight(pub u64);
 
 /// The weight of database operations that the runtime can invoke.
@@ -106,7 +106,7 @@ impl RuntimeDbWeight {
 /// coeff_integer * x^(degree) + coeff_frac * x^(degree)
 /// ```
 ///
-/// The `negative` value encodes whether the term is added or substracted from the
+/// The `negative` value encodes whether the term is added or subtracted from the
 /// overall polynomial result.
 #[derive(Clone, Encode, Decode, TypeInfo)]
 pub struct WeightToFeeCoefficient<Balance> {