feat: OTC fees

pallets/otc-settlements/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = 'pallet-otc-settlements'
-version = '1.0.0'
+version = '1.0.1'
 description = 'A pallet with offchain worker closing OTC arbs'
 authors = ['GalacticCouncil']
 edition = '2021'

pallets/otc-settlements/src/lib.rs

@@ -289,6 +289,10 @@ impl<T: Config> Pallet<T> {
 	/// - `amount`: Amount necessary to close the arb.
 	/// - `route`: The route we trade against. Required for the fee calculation.
 	pub fn settle_otc(otc_id: OrderId, amount: Balance, route: Vec<Trade<AssetIdOf<T>>>) -> DispatchResult {
+		log::debug!(
+			target: "offchain_worker::settle_otc",
+			"calling settle_otc(): otc_id: {:?} amount: {:?} route: {:?}", otc_id, amount, route);
+
 		let pallet_acc = Self::account_id();
 
 		let otc = <pallet_otc::Orders<T>>::get(otc_id).ok_or(Error::<T>::OrderNotFound)?;
@@ -315,8 +319,7 @@ impl<T: Config> Pallet<T> {
 		<T as Config>::Currency::mint_into(asset_a, &pallet_acc, amount)?;
 
 		// get initial otc price
-		let otc_price =
-			FixedU128::checked_from_rational(otc.amount_out, otc.amount_in).ok_or(ArithmeticError::Overflow)?;
+		let otc_price = Self::otc_price(&otc)?;
 
 		// Router trade is disabled in the benchmarks, so disable this one as well.
 		// Without disabling it, the requirements for the extrinsic cannot be met (e.g. profit).
@@ -456,7 +459,7 @@ impl<T: Config> Pallet<T> {
 
 				let mut list = vec![];
 				for (otc_id, otc) in <pallet_otc::Orders<T>>::iter() {
-					let otc_price = FixedU128::checked_from_rational(otc.amount_out, otc.amount_in);
+					let otc_price = Self::otc_price(&otc).ok();
 
 					let route = T::Router::get_route(AssetPair {
 						// To get the correct price, we need to switch the assets, otherwise
@@ -594,4 +597,14 @@ impl<T: Config> Pallet<T> {
 		}
 		None
 	}
+
+	/// Calculates the price (asset_out/asset_in) after subtracting the OTC fee from the amount_out.
+	fn otc_price(otc: &Order<T::AccountId, T::AssetId>) -> Result<FixedU128, DispatchError> {
+		let fee = pallet_otc::Pallet::<T>::calculate_fee(otc.amount_out);
+		Ok(FixedU128::checked_from_rational(
+			otc.amount_out.checked_sub(fee).ok_or(ArithmeticError::Overflow)?,
+			otc.amount_in,
+		)
+		.ok_or(ArithmeticError::Overflow)?)
+	}
 }

pallets/otc-settlements/src/mock.rs

@@ -79,6 +79,7 @@ parameter_types! {
 	pub MinProfitLimit: Balance = 10_000_000_000_000;
 	pub PricePrecision: FixedU128 = FixedU128::from_rational(1, 1_000_000);
 	pub MinProfitPercentage: Perbill = Perbill::from_rational(1u32, 100_000_u32); // 0.001%
+	pub OtcFee: Permill = Permill::from_percent(1u32);
 }
 
 parameter_type_with_key! {
@@ -107,6 +108,8 @@ impl pallet_otc::Config for Test {
 	type RuntimeEvent = RuntimeEvent;
 	type ExistentialDeposits = ExistentialDeposits;
 	type ExistentialDepositMultiplier = ExistentialDepositMultiplier;
+	type Fee = OtcFee;
+	type FeeReceiver = TreasuryAccount;
 	type WeightInfo = ();
 }
 

pallets/otc-settlements/src/tests.rs

@@ -196,7 +196,7 @@ fn profit_should_be_transferred_to_treasury_when_zero_initial_pallet_balance() {
 			HDX,
 			DAI,
 			100_000 * ONE,
-			201_000 * ONE,
+			205_000 * ONE,
 			true,
 		));
 
@@ -226,7 +226,7 @@ fn profit_should_be_transferred_to_treasury_when_nonzero_initial_pallet_balance(
 			HDX,
 			DAI,
 			100_000 * ONE,
-			201_000 * ONE,
+			205_000 * ONE,
 			true,
 		));
 
@@ -258,7 +258,7 @@ fn existing_arb_opportunity_should_trigger_trade() {
 			HDX, // otc asset_in
 			DAI, // otc asset_out
 			100_000 * ONE,
-			201_000 * ONE,
+			205_000 * ONE,
 			true,
 		));
 
@@ -294,7 +294,7 @@ fn existing_arb_opportunity_should_trigger_trade() {
 
 		expect_last_events(vec![Event::Executed {
 			asset_id: HDX,
-			profit: 2_067_802_207_347,
+			profit: 17_736_110_470_326,
 		}
 		.into()]);
 	});
@@ -308,10 +308,8 @@ fn existing_arb_opportunity_should_trigger_trade_when_otc_is_not_partially_filla
 			RuntimeOrigin::signed(ALICE),
 			HDX, // otc asset_in
 			DAI, // otc asset_out
-			// we got following 2 values from the logs of
-			// existing_arb_opportunity_should_trigger_trade test
-			828_170_776_368_178,
-			1_664_623_260_500_037,
+			100_000 * ONE,
+			300_000 * ONE,
 			false, // not partially fillable
 		));
 
@@ -347,7 +345,7 @@ fn existing_arb_opportunity_should_trigger_trade_when_otc_is_not_partially_filla
 
 		expect_last_events(vec![Event::Executed {
 			asset_id: HDX,
-			profit: 2_067_802_207_347,
+			profit: 2_732_618_471_117_260,
 		}
 		.into()]);
 	});
@@ -365,7 +363,7 @@ fn existing_arb_opportunity_of_insufficient_asset_should_trigger_trade() {
 			BTC, // otc asset_in
 			HDX, // otc asset_out
 			200_000 * ONE,
-			101_000 * ONE,
+			105_000 * ONE,
 			true,
 		));
 
@@ -401,7 +399,7 @@ fn existing_arb_opportunity_of_insufficient_asset_should_trigger_trade() {
 
 		expect_last_events(vec![Event::Executed {
 			asset_id: BTC,
-			profit: 16_419_654_005_878,
+			profit: 245_338_363_920_576,
 		}
 		.into()]);
 	});
@@ -416,15 +414,15 @@ fn multiple_arb_opportunities_should_trigger_trades() {
 			HDX, // otc asset_in
 			DAI, // otc asset_out
 			100_000 * ONE,
-			201_000 * ONE,
+			205_000 * ONE,
 			true,
 		));
 		assert_ok!(OTC::place_order(
 			RuntimeOrigin::signed(ALICE),
 			DOT, // otc asset_in
 			KSM, // otc asset_out
 			100_000 * ONE,
-			101_000 * ONE,
+			102_000 * ONE,
 			true,
 		));
 
@@ -433,12 +431,12 @@ fn multiple_arb_opportunities_should_trigger_trades() {
 		expect_events(vec![
 			Event::Executed {
 				asset_id: HDX,
-				profit: 2_067_802_207_347,
+				profit: 17736110470326,
 			}
 			.into(),
 			Event::Executed {
 				asset_id: DOT,
-				profit: 12_345_450_557_916,
+				profit: 11860096179879,
 			}
 			.into(),
 		]);
@@ -476,7 +474,7 @@ fn trade_should_be_triggered_when_arb_opportunity_appears() {
 		<OtcSettlements as Hooks<BlockNumberFor<Test>>>::offchain_worker(System::block_number());
 
 		// make a trade to move the price and create an arb opportunity
-		assert_ok!(Omnipool::sell(RuntimeOrigin::signed(ALICE), HDX, DAI, 1_000 * ONE, ONE,));
+		assert_ok!(Omnipool::sell(RuntimeOrigin::signed(ALICE), HDX, DAI, 3_000 * ONE, ONE,));
 
 		System::set_block_number(System::block_number() + 1);
 
@@ -510,7 +508,7 @@ fn trade_should_be_triggered_when_arb_opportunity_appears() {
 
 		expect_last_events(vec![Event::Executed {
 			asset_id: HDX,
-			profit: 2_981_065_139_674,
+			profit: 5_173_145_606_735,
 		}
 		.into()]);
 	});
@@ -619,7 +617,7 @@ fn test_offchain_worker_unsigned_transaction_submission() {
 			HDX, // otc asset_in
 			DAI, // otc asset_out
 			100_000 * ONE,
-			201_000 * ONE,
+			205_000 * ONE,
 			true,
 		));
 
@@ -641,7 +639,7 @@ fn test_offchain_worker_unsigned_transaction_submission() {
 			tx.call,
 			crate::mock::RuntimeCall::OtcSettlements(crate::Call::settle_otc_order {
 				otc_id: 0,
-				amount: 828_170_776_368_178,
+				amount: 2_413_749_694_825_193,
 				route,
 			})
 		);
@@ -657,7 +655,7 @@ fn test_offchain_worker_signed_transaction_submission() {
 			HDX, // otc asset_in
 			DAI, // otc asset_out
 			100_000 * ONE,
-			201_000 * ONE,
+			205_000 * ONE,
 			true,
 		));
 
@@ -671,7 +669,7 @@ fn test_offchain_worker_signed_transaction_submission() {
 		assert_ok!(OtcSettlements::settle_otc_order(
 			RuntimeOrigin::signed(ALICE),
 			otc_id,
-			828_170_776_368_178,
+			2_413_749_694_825_193,
 			route,
 		));
 	})

pallets/otc/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = 'pallet-otc'
-version = '1.1.5'
+version = '2.0.0'
 description = 'A pallet for trustless over-the-counter trading'
 authors = ['GalacticCouncil']
 edition = '2021'

pallets/otc/README.md

@@ -2,7 +2,8 @@
 ## General description
 This pallet provides basic over-the-counter (OTC) trading functionality.
 It allows anyone to `place_order` by specifying a pair of assets (in and out), their respective amounts, and
-whether the order is partially fillable. The order price is static and calculated as `amount_out / amount_in`.
+whether the order is partially fillable. Fee is applied to all trades and is deducted from the `amount_out`.
+Because of the fee, the order price is static and calculated as `(amount_out - fee) / amount_in`.
 
 ## Notes
 The pallet implements a minimum order size as an alternative to storage fees. The amounts of an open order cannot