XCM: Properly set the pricing for the DMP router

runtime/kusama/src/xcm_config.rs

@@ -17,7 +17,7 @@
 //! XCM configurations for the Kusama runtime.
 
 use super::{
-	parachains_origin, AccountId, AllPalletsWithSystem, Balances, CouncilCollective, Fellows,
+	parachains_origin, AccountId, AllPalletsWithSystem, Balances, CouncilCollective, Dmp, Fellows,
 	ParaId, Runtime, RuntimeCall, RuntimeEvent, RuntimeOrigin, StakingAdmin, WeightToFee,
 	XcmPallet,
 };
@@ -26,8 +26,14 @@ use frame_support::{
 	traits::{Contains, Everything, Nothing},
 	weights::Weight,
 };
-use runtime_common::{paras_registrar, xcm_sender, ToAuthor};
+use kusama_runtime_constants::currency::CENTS;
+use runtime_common::{
+	paras_registrar,
+	xcm_sender::{ChildParachainRouter, PriceForParachainDelivery},
+	ToAuthor,
+};
 use sp_core::ConstU32;
+use sp_runtime::{traits::Saturating, Percent};
 use xcm::latest::prelude::*;
 use xcm_builder::{
 	AccountId32Aliases, AllowExplicitUnpaidExecutionFrom, AllowKnownQueryResponses,
@@ -103,11 +109,22 @@ parameter_types! {
 	pub const MaxInstructions: u32 = 100;
 }
 
+pub struct ExponentialKsmPrice;
+impl PriceForParachainDelivery for ExponentialKsmPrice {
+	fn price_for_parachain_delivery(para: ParaId, _: &Xcm<()>) -> MultiAssets {
+		let factor = Percent::from_percent(101).saturating_pow(Dmp::dmq_length(para) as usize);
+		let base = CENTS.saturating_mul(3);
+
+		let amount = factor * base;
+		(Here, amount).into()
+	}
+}
+
 /// The XCM router. When we want to send an XCM message, we use this type. It amalgamates all of our
 /// individual routers.
 pub type XcmRouter = (
 	// Only one router so far - use DMP to communicate with child parachains.
-	xcm_sender::ChildParachainRouter<Runtime, XcmPallet, ()>,
+	ChildParachainRouter<Runtime, XcmPallet, ExponentialKsmPrice>,
 );
 
 parameter_types! {

runtime/parachains/src/dmp.rs

@@ -247,7 +247,7 @@ impl<T: Config> Pallet<T> {
 	/// Returns the number of pending downward messages addressed to the given para.
 	///
 	/// Returns 0 if the para doesn't have an associated downward message queue.
-	pub(crate) fn dmq_length(para: ParaId) -> u32 {
+	pub fn dmq_length(para: ParaId) -> u32 {
 		<Self as Store>::DownwardMessageQueues::decode_len(&para)
 			.unwrap_or(0)
 			.saturated_into::<u32>()

runtime/polkadot/src/xcm_config.rs

@@ -17,16 +17,22 @@
 //! XCM configuration for Polkadot.
 
 use super::{
-	parachains_origin, AccountId, AllPalletsWithSystem, Balances, CouncilCollective, ParaId,
+	parachains_origin, AccountId, AllPalletsWithSystem, Balances, CouncilCollective, Dmp, ParaId,
 	Runtime, RuntimeCall, RuntimeEvent, RuntimeOrigin, WeightToFee, XcmPallet,
 };
 use frame_support::{
 	match_types, parameter_types,
 	traits::{Contains, Everything, Nothing},
 	weights::Weight,
 };
-use runtime_common::{paras_registrar, xcm_sender, ToAuthor};
+use polkadot_runtime_constants::currency::CENTS;
+use runtime_common::{
+	paras_registrar,
+	xcm_sender::{ChildParachainRouter, PriceForParachainDelivery},
+	ToAuthor,
+};
 use sp_core::ConstU32;
+use sp_runtime::{traits::Saturating, Percent};
 use xcm::latest::prelude::*;
 use xcm_builder::{
 	AccountId32Aliases, AllowKnownQueryResponses, AllowSubscriptionsFrom,
@@ -101,11 +107,22 @@ parameter_types! {
 	pub const MaxInstructions: u32 = 100;
 }
 
+pub struct ExponentialDotPrice;
+impl PriceForParachainDelivery for ExponentialDotPrice {
+	fn price_for_parachain_delivery(para: ParaId, _: &Xcm<()>) -> MultiAssets {
+		let factor = Percent::from_percent(101).saturating_pow(Dmp::dmq_length(para) as usize);
+		let base = CENTS.saturating_mul(3);
+
+		let amount = factor * base;
+		(Here, amount).into()
+	}
+}
+
 /// The XCM router. When we want to send an XCM message, we use this type. It amalgamates all of our
 /// individual routers.
 pub type XcmRouter = (
 	// Only one router so far - use DMP to communicate with child parachains.
-	xcm_sender::ChildParachainRouter<Runtime, XcmPallet, ()>,
+	ChildParachainRouter<Runtime, XcmPallet, ExponentialDotPrice>,
 );
 
 parameter_types! {

runtime/rococo/src/xcm_config.rs

@@ -17,16 +17,22 @@
 //! XCM configuration for Rococo.
 
 use super::{
-	parachains_origin, AccountId, AllPalletsWithSystem, Balances, CouncilCollective, ParaId,
+	parachains_origin, AccountId, AllPalletsWithSystem, Balances, CouncilCollective, Dmp, ParaId,
 	Runtime, RuntimeCall, RuntimeEvent, RuntimeOrigin, WeightToFee, XcmPallet,
 };
 use frame_support::{
 	match_types, parameter_types,
 	traits::{Contains, Everything, Nothing},
 	weights::Weight,
 };
-use runtime_common::{paras_registrar, xcm_sender, ToAuthor};
+use rococo_runtime_constants::currency::CENTS;
+use runtime_common::{
+	paras_registrar,
+	xcm_sender::{ChildParachainRouter, PriceForParachainDelivery},
+	ToAuthor,
+};
 use sp_core::ConstU32;
+use sp_runtime::{traits::Saturating, Percent};
 use xcm::latest::prelude::*;
 use xcm_builder::{
 	AccountId32Aliases, AllowExplicitUnpaidExecutionFrom, AllowKnownQueryResponses,
@@ -82,11 +88,23 @@ parameter_types! {
 	/// The amount of weight an XCM operation takes. This is a safe overestimate.
 	pub const BaseXcmWeight: Weight = Weight::from_parts(1_000_000_000, 64 * 1024);
 }
+
+pub struct ExponentialRocPrice;
+impl PriceForParachainDelivery for ExponentialRocPrice {
+	fn price_for_parachain_delivery(para: ParaId, _: &Xcm<()>) -> MultiAssets {
+		let factor = Percent::from_percent(101).saturating_pow(Dmp::dmq_length(para) as usize);
+		let base = CENTS.saturating_mul(3);
+
+		let amount = factor * base;
+		(Here, amount).into()
+	}
+}
+
 /// The XCM router. When we want to send an XCM message, we use this type. It amalgamates all of our
 /// individual routers.
 pub type XcmRouter = (
 	// Only one router so far - use DMP to communicate with child parachains.
-	xcm_sender::ChildParachainRouter<Runtime, XcmPallet, ()>,
+	ChildParachainRouter<Runtime, XcmPallet, ExponentialRocPrice>,
 );
 
 parameter_types! {

runtime/westend/src/xcm_config.rs

@@ -17,15 +17,21 @@
 //! XCM configurations for Westend.
 
 use super::{
-	parachains_origin, weights, AccountId, AllPalletsWithSystem, Balances, ParaId, Runtime,
+	parachains_origin, weights, AccountId, AllPalletsWithSystem, Balances, Dmp, ParaId, Runtime,
 	RuntimeCall, RuntimeEvent, RuntimeOrigin, WeightToFee, XcmPallet,
 };
 use frame_support::{
 	parameter_types,
 	traits::{Contains, Everything, Nothing},
 };
-use runtime_common::{paras_registrar, xcm_sender, ToAuthor};
+use runtime_common::{
+	paras_registrar,
+	xcm_sender::{ChildParachainRouter, PriceForParachainDelivery},
+	ToAuthor,
+};
 use sp_core::ConstU32;
+use sp_runtime::{traits::Saturating, Percent};
+use westend_runtime_constants::currency::CENTS;
 use xcm::latest::prelude::*;
 use xcm_builder::{
 	AccountId32Aliases, AllowExplicitUnpaidExecutionFrom, AllowKnownQueryResponses,
@@ -68,11 +74,22 @@ type LocalOriginConverter = (
 	ChildSystemParachainAsSuperuser<ParaId, RuntimeOrigin>,
 );
 
+pub struct ExponentialWndPrice;
+impl PriceForParachainDelivery for ExponentialWndPrice {
+	fn price_for_parachain_delivery(para: ParaId, _: &Xcm<()>) -> MultiAssets {
+		let factor = Percent::from_percent(101).saturating_pow(Dmp::dmq_length(para) as usize);
+		let base = CENTS.saturating_mul(3);
+
+		let amount = factor * base;
+		(Here, amount).into()
+	}
+}
+
 /// The XCM router. When we want to send an XCM message, we use this type. It amalgamates all of our
 /// individual routers.
 pub type XcmRouter = (
 	// Only one router so far - use DMP to communicate with child parachains.
-	xcm_sender::ChildParachainRouter<Runtime, XcmPallet, ()>,
+	ChildParachainRouter<Runtime, XcmPallet, ExponentialWndPrice>,
 );
 
 parameter_types! {

xcm/pallet-xcm/src/lib.rs

@@ -1144,7 +1144,10 @@ impl<T: Config> Pallet<T> {
 			BuyExecution { fees, weight_limit },
 			DepositAsset { assets: Wild(AllCounted(max_assets)), beneficiary },
 		]);
-		let mut message = Xcm(vec![TransferReserveAsset { assets, dest, xcm }]);
+		let mut message = Xcm(vec![
+			SetFeesMode { jit_withdraw: true },
+			TransferReserveAsset { assets, dest, xcm },
+		]);
 		let weight =
 			T::Weigher::weight(&mut message).map_err(|()| Error::<T>::UnweighableMessage)?;
 		let hash = message.using_encoded(sp_io::hashing::blake2_256);
@@ -1201,8 +1204,11 @@ impl<T: Config> Pallet<T> {
 			BuyExecution { fees, weight_limit },
 			DepositAsset { assets: Wild(AllCounted(max_assets)), beneficiary },
 		]);
-		let mut message =
-			Xcm(vec![WithdrawAsset(assets), InitiateTeleport { assets: Wild(All), dest, xcm }]);
+		let mut message = Xcm(vec![
+			WithdrawAsset(assets),
+			SetFeesMode { jit_withdraw: true },
+			InitiateTeleport { assets: Wild(All), dest, xcm },
+		]);
 		let weight =
 			T::Weigher::weight(&mut message).map_err(|()| Error::<T>::UnweighableMessage)?;
 		let hash = message.using_encoded(sp_io::hashing::blake2_256);