chore: benchmark approve

pallets/api/Cargo.toml

@@ -33,6 +33,8 @@ runtime-benchmarks = [
     "frame-benchmarking/runtime-benchmarks",
     "frame-support/runtime-benchmarks",
     "frame-system/runtime-benchmarks",
+    "pallet-assets/runtime-benchmarks",
+    "pallet-balances/runtime-benchmarks",
     "sp-runtime/runtime-benchmarks",
 ]
 std = [

pallets/api/src/fungibles/benchmarking.rs

@@ -0,0 +1,60 @@
+//! Benchmarking setup for pallet-cards
+
+use super::{AccountIdOf, AssetIdOf, Assets, AssetsInstanceOf, BalanceOf, Call, Config, Pallet};
+use frame_benchmarking::{account, v2::*};
+use frame_support::{
+	assert_ok,
+	traits::{
+		fungibles::{
+			approvals::{Inspect as ApprovalInspect, Mutate},
+			Create, Inspect,
+		},
+		Currency,
+	},
+};
+use frame_system::RawOrigin;
+use sp_runtime::traits::Zero;
+
+const SEED: u32 = 1;
+
+#[benchmarks(
+	where
+	<pallet_assets::Pallet<T, AssetsInstanceOf<T>> as Inspect<<T as frame_system::Config>::AccountId>>::AssetId: Zero,
+)]
+mod benchmarks {
+	use super::*;
+
+	// The worst case scenario is when the allowance is set to a value which is lower than the
+	// current allowance.
+	#[benchmark]
+	fn approve() -> Result<(), BenchmarkError> {
+		let asset = AssetIdOf::<T>::zero();
+		let decreased_value = <BalanceOf<T>>::from(50u32);
+		let min_balance = <BalanceOf<T>>::from(1u32);
+		let owner: AccountIdOf<T> = account("Alice", 0, SEED);
+		let spender: AccountIdOf<T> = account("Bob", 0, SEED);
+		let value = <BalanceOf<T>>::from(100u32);
+		T::Currency::make_free_balance_be(&owner, 100u32.into());
+		assert_ok!(<Assets<T> as Create<AccountIdOf<T>>>::create(
+			asset.clone().into(),
+			owner.clone(),
+			true,
+			min_balance
+		));
+		assert_ok!(<Assets<T> as Mutate<AccountIdOf<T>>>::approve(
+			asset.clone(),
+			&owner,
+			&spender,
+			value
+		));
+
+		#[extrinsic_call]
+		_(RawOrigin::Signed(owner.clone()), asset.clone(), spender.clone(), decreased_value);
+
+		assert_eq!(Assets::<T>::allowance(asset, &owner, &spender), decreased_value);
+
+		Ok(())
+	}
+
+	impl_benchmark_test_suite!(Pallet, crate::mock::new_test_ext(), crate::mock::Test);
+}

pallets/api/src/fungibles/mod.rs

@@ -3,6 +3,8 @@
 /// API that adheres to standards in the smart contract space.
 pub use pallet::*;
 
+#[cfg(feature = "runtime-benchmarks")]
+mod benchmarking;
 #[cfg(test)]
 mod tests;
 
@@ -26,8 +28,8 @@ pub mod pallet {
 	>>::AssetId;
 	type AssetIdParameterOf<T> =
 		<T as pallet_assets::Config<AssetsInstanceOf<T>>>::AssetIdParameter;
-	type Assets<T> = pallet_assets::Pallet<T, AssetsInstanceOf<T>>;
-	type AssetsInstanceOf<T> = <T as Config>::AssetsInstance;
+	pub(crate) type Assets<T> = pallet_assets::Pallet<T, AssetsInstanceOf<T>>;
+	pub(crate) type AssetsInstanceOf<T> = <T as Config>::AssetsInstance;
 	type AssetsWeightInfo<T> = <T as pallet_assets::Config<AssetsInstanceOf<T>>>::WeightInfo;
 	pub(crate) type BalanceOf<T> = <pallet_assets::Pallet<T, AssetsInstanceOf<T>> as Inspect<
 		<T as frame_system::Config>::AccountId,
@@ -94,14 +96,15 @@ pub mod pallet {
 		/// # Returns
 		/// Returns `Ok(())` if successful, or an error if the approval fails.
 		#[pallet::call_index(2)]
-		#[pallet::weight(T::DbWeight::get().reads(2) + AssetsWeightInfo::<T>::cancel_approval() + AssetsWeightInfo::<T>::approve_transfer())]
+		#[pallet::weight(T::DbWeight::get().reads(1) + AssetsWeightInfo::<T>::cancel_approval() + AssetsWeightInfo::<T>::approve_transfer())]
 		pub fn approve(
 			origin: OriginFor<T>,
 			id: AssetIdOf<T>,
 			spender: AccountIdOf<T>,
 			mut value: BalanceOf<T>,
 		) -> DispatchResultWithPostInfo {
 			let who = ensure_signed(origin.clone())
+				// To have the caller pay some fees.
 				.map_err(|e| e.with_weight(T::DbWeight::get().reads(1)))?;
 			let current_allowance = Assets::<T>::allowance(id.clone(), &who, &spender);
 			let spender = T::Lookup::unlookup(spender);
@@ -115,15 +118,15 @@ pub mod pallet {
 				value.saturating_reduce(current_allowance);
 				Assets::<T>::approve_transfer(origin, id, spender, value).map_err(|e| {
 					e.with_weight(
-						T::DbWeight::get().reads(2) + AssetsWeightInfo::<T>::approve_transfer(),
+						T::DbWeight::get().reads(1) + AssetsWeightInfo::<T>::approve_transfer(),
 					)
 				})?;
 			} else {
 				// If the new value is less than the current allowance, cancel the approval and set the new value
 				Assets::<T>::cancel_approval(origin.clone(), id.clone(), spender.clone()).map_err(
 					|e| {
 						e.with_weight(
-							T::DbWeight::get().reads(2) + AssetsWeightInfo::<T>::cancel_approval(),
+							T::DbWeight::get().reads(1) + AssetsWeightInfo::<T>::cancel_approval(),
 						)
 					},
 				)?;