feat: reduce coupling between salary and core-fellowship pallet

cumulus/parachains/runtimes/collectives/collectives-westend/src/ambassador/mod.rs

@@ -223,6 +223,7 @@ impl pallet_core_fellowship::Config<AmbassadorCoreInstance> for Runtime {
 	type FastPromoteOrigin = Self::PromoteOrigin;
 	type EvidenceSize = ConstU32<65536>;
 	type MaxRank = ConstU32<9>;
+	type PayoutPeriodDuration = ConstU32<1>;
 }
 
 pub type AmbassadorSalaryInstance = pallet_salary::Instance2;

substrate/frame/core-fellowship/src/lib.rs

@@ -119,11 +119,14 @@ pub struct ParamsType<
 	Balance: Clone + Eq + PartialEq + Debug,
 	BlockNumber: Clone + Eq + PartialEq + Debug,
 	Ranks: Get<u32>,
+	PayoutPeriodDuration: Get<BlockNumber>,
 > {
-	/// The amounts to be paid when a member of a given rank (-1) is active.
-	pub active_salary: BoundedVec<Balance, Ranks>,
-	/// The amounts to be paid when a member of a given rank (-1) is passive.
-	pub passive_salary: BoundedVec<Balance, Ranks>,
+	/// The amounts to be paid per `PayoutPeriod` when a member of a given rank (-1) is active.
+	pub active_salary_per_period: BoundedVec<Balance, Ranks>,
+	/// The amounts to be paid per `PayoutPeriod` when a member of a given rank (-1) is passive.
+	pub passive_salary_per_period: BoundedVec<Balance, Ranks>,
+	/// The number of blocks between two payout periods.
+	pub payout_period_duration: PayoutPeriodDuration,
 	/// The period between which unproven members become demoted.
 	pub demotion_period: BoundedVec<BlockNumber, Ranks>,
 	/// The period between which members must wait before they may proceed to this rank.
@@ -140,8 +143,9 @@ impl<
 {
 	fn default() -> Self {
 		Self {
-			active_salary: Default::default(),
-			passive_salary: Default::default(),
+			active_salary_per_period: Default::default(),
+			passive_salary_per_period: Default::default(),
+			payout_period_duration: Default::default(),
 			demotion_period: Default::default(),
 			min_promotion_period: Default::default(),
 			offboard_timeout: BlockNumber::default(),
@@ -225,6 +229,12 @@ pub mod pallet {
 		/// Increasing this value is supported, but decreasing it may lead to a broken state.
 		#[pallet::constant]
 		type MaxRank: Get<u32>;
+
+		/// The number of blocks between two payout periods.
+		///
+		/// This is used to calculate the payout amount for each period.
+		#[pallet::constant]
+		type PayoutPeriodDuration: Get<BlockNumberFor<Self>>;
 	}
 
 	pub type ParamsOf<T, I> =
@@ -629,6 +639,9 @@ pub mod pallet {
 					&mut p.passive_salary,
 					partial_params.passive_salary,
 				);
+				if let Some(new_payout_period) = partial_params.payout_period_duration {
+					p.payout_period = new_payout_period;
+				}
 				Self::set_partial_params_slice(
 					&mut p.demotion_period,
 					partial_params.demotion_period,
@@ -691,9 +704,12 @@ pub mod pallet {
 				None => return Zero::zero(),
 			};
 			let params = Params::<T, I>::get();
-			let salary =
-				if member.is_active { params.active_salary } else { params.passive_salary };
-			salary[index]
+			let salary_per_period = if member.is_active {
+				params.active_salary_per_period
+			} else {
+				params.passive_salary_per_period
+			};
+			salary_per_period[index]
 		}
 	}
 }

substrate/frame/core-fellowship/src/migration.rs

@@ -84,8 +84,13 @@ impl<T: Config<I>, I: 'static> UncheckedOnRuntimeUpgrade for MigrateToV1<T, I> {
 		let old_value = v0::Params::<T, I>::take();
 		// Write the new value to storage
 		let new = crate::ParamsType {
-			active_salary: BoundedVec::defensive_truncate_from(old_value.active_salary.to_vec()),
-			passive_salary: BoundedVec::defensive_truncate_from(old_value.passive_salary.to_vec()),
+			active_salary_per_period: BoundedVec::defensive_truncate_from(
+				old_value.active_salary.to_vec(),
+			),
+			passive_salary_per_period: BoundedVec::defensive_truncate_from(
+				old_value.passive_salary.to_vec(),
+			),
+			payout_period_duration: old_value.payout_period,
 			demotion_period: BoundedVec::defensive_truncate_from(
 				old_value.demotion_period.to_vec(),
 			),

substrate/frame/salary/src/lib.rs

@@ -392,6 +392,12 @@ pub mod pallet {
 		pub fn cycle_period() -> BlockNumberFor<T> {
 			T::RegistrationPeriod::get() + T::PayoutPeriod::get()
 		}
+		fn calculate_periods_to_pay(last_payout: BlockNumberFor<T>, now: BlockNumberFor<T>) -> u32 {
+			// TODO: retrieve payout period from core-fellowship config?
+			let payout_period = T::PayoutPeriod::get();
+			let elapsed = now.saturating_sub(last_payout);
+			(elapsed / payout_period) as u32
+		}
 		fn do_payout(who: T::AccountId, beneficiary: T::AccountId) -> DispatchResult {
 			let mut status = Status::<T, I>::get().ok_or(Error::<T, I>::NotStarted)?;
 			let mut claimant = Claimant::<T, I>::get(&who).ok_or(Error::<T, I>::NotInducted)?;
@@ -418,7 +424,9 @@ pub mod pallet {
 				Nothing | Attempted { .. } if claimant.last_active < status.cycle_index => {
 					// Not registered for this cycle. Pay from whatever is left.
 					let rank = T::Members::rank_of(&who).ok_or(Error::<T, I>::NotMember)?;
-					let ideal_payout = T::Salary::get_salary(rank, &who);
+					let salary_per_period = T::Salary::get_salary(rank, &who);
+					let periods_to_pay = Self::calculate_periods_to_pay(status.cycle_start, now);
+					let ideal_payout = salary_per_period.saturating_mul(periods_to_pay.into());
 
 					let pot = status
 						.budget