Refactor function related to issuing (#1371)

* Rename

* Refactor inflation

* Refactor

* Doc

* Correct doc

---------

Co-authored-by: fisher <hackfisher@gmail.com>

.github/workflows/release.yml

@@ -216,7 +216,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: [build-nodes, build-runtimes, publish-docker-image]
     steps:
-      - name: Fetch template
+      - name: Fetch note template
         uses: actions/checkout@v4
       - name: Download nodes and runtimes
         uses: actions/download-artifact@v4

core/inflation/src/lib.rs

@@ -28,50 +28,129 @@ mod test;
 // crates.io
 use primitive_types::U256;
 // darwinia
-use dc_types::{Balance, Moment, UNIT};
+use dc_types::{Balance, Moment};
 // github
-use substrate_fixed::{
-	transcendental,
-	types::{I95F33, U94F34},
-};
-
-/// Inflation's upper limit.
-pub const TOTAL_SUPPLY: Balance = 10_000_000_000 * UNIT;
+use substrate_fixed::types::U94F34;
 
 /// Milliseconds per year.
 pub const MILLISECS_PER_YEAR: Balance = (366 * 24 * 60 * 60) * 1000;
 
-/// Compute the inflation of a period.
+/// Issuing maps for ages 1 to 100 years.
+pub const ISSUING_MAP: [Balance; 100] = [
+	80000000000000000000000000,
+	111773286000000000000000000,
+	134746987000000000000000000,
+	152702244000000000000000000,
+	167131169000000000000000000,
+	178823309000000000000000000,
+	188269287000000000000000000,
+	195807995000000000000000000,
+	201691935000000000000000000,
+	206120192000000000000000000,
+	209256584000000000000000000,
+	211240393000000000000000000,
+	212192983000000000000000000,
+	212222105000000000000000000,
+	211424760000000000000000000,
+	209889162000000000000000000,
+	207696140000000000000000000,
+	204920129000000000000000000,
+	201629917000000000000000000,
+	197889213000000000000000000,
+	193757076000000000000000000,
+	189288266000000000000000000,
+	184533528000000000000000000,
+	179539841000000000000000000,
+	174350616000000000000000000,
+	169005897000000000000000000,
+	163542519000000000000000000,
+	157994277000000000000000000,
+	152392074000000000000000000,
+	146764063000000000000000000,
+	141135790000000000000000000,
+	135530328000000000000000000,
+	129968413000000000000000000,
+	124468570000000000000000000,
+	119047241000000000000000000,
+	113718915000000000000000000,
+	108496242000000000000000000,
+	103390155000000000000000000,
+	98409990000000000000000000,
+	93563591000000000000000000,
+	88857424000000000000000000,
+	84296682000000000000000000,
+	79885385000000000000000000,
+	75626479000000000000000000,
+	71521926000000000000000000,
+	67572800000000000000000000,
+	63779363000000000000000000,
+	60141155000000000000000000,
+	56657064000000000000000000,
+	53325400000000000000000000,
+	50143962000000000000000000,
+	47110103000000000000000000,
+	44220789000000000000000000,
+	41472652000000000000000000,
+	38862045000000000000000000,
+	36385086000000000000000000,
+	34037705000000000000000000,
+	31815679000000000000000000,
+	29714676000000000000000000,
+	27730281000000000000000000,
+	25858032000000000000000000,
+	24093442000000000000000000,
+	22432030000000000000000000,
+	20869335000000000000000000,
+	19400942000000000000000000,
+	18022495000000000000000000,
+	16729714000000000000000000,
+	15518406000000000000000000,
+	14384477000000000000000000,
+	13323941000000000000000000,
+	12332926000000000000000000,
+	11407684000000000000000000,
+	10544591000000000000000000,
+	9740153000000000000000000,
+	8991010000000000000000000,
+	8293934000000000000000000,
+	7645831000000000000000000,
+	7043743000000000000000000,
+	6484844000000000000000000,
+	5966438000000000000000000,
+	5485963000000000000000000,
+	5040980000000000000000000,
+	4629177000000000000000000,
+	4248363000000000000000000,
+	3896462000000000000000000,
+	3571515000000000000000000,
+	3271673000000000000000000,
+	2995191000000000000000000,
+	2740429000000000000000000,
+	2505842000000000000000000,
+	2289982000000000000000000,
+	2091489000000000000000000,
+	1909087000000000000000000,
+	1741584000000000000000000,
+	1587865000000000000000000,
+	1446887000000000000000000,
+	1317679000000000000000000,
+	1199333000000000000000000,
+	1091005000000000000000000,
+	991910000000000000000000,
+];
+
+/// Calculate the issuing of a period.
 ///
 /// Use `U94F34` here, because `2^94 > TOTAL_SUPPLY * 10^18`.
-pub fn in_period(unminted: Balance, period: Moment, elapsed: Moment) -> Option<Balance> {
-	let unminted_per_millisecs = U94F34::checked_from_num(unminted)? / MILLISECS_PER_YEAR;
-	let x =
-		(unminted_per_millisecs.checked_mul(U94F34::checked_from_num(period)?)?).floor().to_num();
-	let years = (elapsed / MILLISECS_PER_YEAR + 1) as _;
-
-	inflate(x, years)
-}
-
-// Compute the inflation.
-//
-// Formula:
-// ```
-// x * (1 - (99 / 100) ^ sqrt(years));
-// ```
-//
-// Use `I95F33` here, because `2^94 > TOTAL_SUPPLY * 10^18`.
-fn inflate(x: Balance, years: u8) -> Option<Balance> {
-	let sqrt = transcendental::sqrt::<I95F33, I95F33>(years.into()).ok()?;
-	let ninety_nine = I95F33::from_num(99_u8) / 100_i128;
-	let pow = transcendental::pow::<I95F33, I95F33>(ninety_nine, sqrt).ok()?;
-	let ratio = I95F33::from_num(1_u8) - pow;
-	let inflation = I95F33::checked_from_num(x)? * ratio;
+pub fn issuing_in_period(period: Moment, elapsed: Moment) -> Option<Balance> {
+	let years = (elapsed / MILLISECS_PER_YEAR) as usize;
+	let to_issue = ISSUING_MAP[years];
+	let to_issue_per_millisecs = U94F34::checked_from_num(to_issue)? / MILLISECS_PER_YEAR;
 
-	Some(inflation.floor().to_num())
+	Some(to_issue_per_millisecs.checked_mul(U94F34::checked_from_num(period)?)?.floor().to_num())
 }
 
-/// Compute the reward of a deposit.
+/// Calculate the reward of a deposit.
 ///
 /// Reference(s):
 /// - <https://github.com/evolutionlandorg/bank/blob/master/contracts/GringottsBank.sol#L280>

core/inflation/src/test.rs

@@ -18,9 +18,43 @@
 
 // darwinia
 use crate::*;
+use dc_types::UNIT;
+// github
+use substrate_fixed::{transcendental, types::I95F33};
+
+// Generate the issuing map.
+//
+// Formula:
+// ```
+// unissued * (1 - (99 / 100) ^ sqrt(years));
+// ```
+//
+// Use `I95F33` here, because `2^94 > TOTAL_SUPPLY * 10^18`.
+fn issuing_map() -> Vec<Balance> {
+	let ninety_nine = I95F33::from_num(99_u8) / 100_i128;
+	let max = 10_000_000_000_u128;
+	let mut supply = 2_000_000_000_u128;
+
+	(1_u8..=100)
+		.map(|years| {
+			let sqrt = transcendental::sqrt::<I95F33, I95F33>(years.into()).unwrap();
+			let pow = transcendental::pow::<I95F33, I95F33>(ninety_nine, sqrt).unwrap();
+			let ratio = I95F33::from_num(1_u8) - pow;
+			let unissued = max - supply;
+			let to_issue =
+				(I95F33::checked_from_num(unissued).unwrap() * ratio).floor().to_num::<Balance>();
+
+			supply += to_issue;
+
+			to_issue * UNIT
+		})
+		.collect()
+}
 
 #[test]
-fn inflate_should_work() {
+fn issuing_map_should_work() {
+	assert_eq!(issuing_map(), ISSUING_MAP);
+
 	let max = 10_000_000_000_u128 * UNIT;
 	let init = 2_000_000_000_u128 * UNIT;
 	#[allow(clippy::approx_constant)]
@@ -33,21 +67,19 @@ fn inflate_should_work() {
 		0.08, 0.07, 0.07, 0.06, 0.06, 0.05, 0.05, 0.04, 0.04, 0.04, 0.03, 0.03, 0.03, 0.03, 0.02,
 		0.02, 0.02, 0.02, 0.02, 0.01, 0.01, 0.01, 0.01, 0.01,
 	];
-	let mut unminted = max - init;
+	let mut unissued = max - init;
 
-	for (&rate, years) in rates.iter().zip(1..) {
-		let inflation =
-			in_period(unminted, MILLISECS_PER_YEAR, (years - 1) as u128 * MILLISECS_PER_YEAR)
-				.unwrap();
+	rates.iter().zip(0..).for_each(|(rate, years)| {
+		let issued = issuing_in_period(MILLISECS_PER_YEAR, years * MILLISECS_PER_YEAR).unwrap();
 
 		sp_arithmetic::assert_eq_error_rate!(
-			inflation as f64 / (max - unminted) as f64,
-			rate / 100_f64,
+			issued as f64 / (max - unissued) as f64,
+			*rate / 100_f64,
 			0.0001_f64
 		);
 
-		unminted -= inflation;
-	}
+		unissued -= issued;
+	});
 }
 
 #[test]

pallet/account-migration/src/mock.rs

@@ -162,7 +162,7 @@ impl darwinia_deposit::Config for Runtime {
 impl darwinia_staking::Config for Runtime {
 	type Currency = Balances;
 	type Deposit = Deposit;
-	type InflationManager = ();
+	type IssuingManager = ();
 	type Kton = Dummy;
 	type MaxDeposits = ();
 	type MaxUnstakings = ();

pallet/staking/src/lib.rs

@@ -123,7 +123,7 @@ pub mod pallet {
 		type Currency: Currency<Self::AccountId>;
 
 		/// Inflation and reward manager.
-		type InflationManager: InflationManager<Self>;
+		type IssuingManager: IssuingManager<Self>;
 
 		/// Pass [`pallet_session::Config::ShouldEndSession`]'s result to here.
 		type ShouldEndSession: Get<bool>;
@@ -902,7 +902,7 @@ pub mod pallet {
 				<PendingRewards<T>>::mutate(&c, |u| *u = u.map(|u| u + r).or(Some(r)));
 
 				// TODO: merge into one call
-				if T::InflationManager::reward(&staking_pot, r).is_ok() {
+				if T::IssuingManager::reward(&staking_pot, r).is_ok() {
 					actual_reward += r;
 				} else {
 					unpaid += r;
@@ -936,14 +936,14 @@ pub mod pallet {
 					// If the collator nominated themselves.
 
 					c_payout += n_payout;
-				} else if T::InflationManager::reward(&n_exposure.who, n_payout).is_ok() {
+				} else if T::IssuingManager::reward(&n_exposure.who, n_payout).is_ok() {
 					Self::deposit_event(Event::Payout { staker: n_exposure.who, amount: n_payout });
 				} else {
 					Self::deposit_event(Event::Unpaid { staker: n_exposure.who, amount: n_payout });
 				}
 			}
 
-			if T::InflationManager::reward(&collator, c_payout).is_ok() {
+			if T::IssuingManager::reward(&collator, c_payout).is_ok() {
 				Self::deposit_event(Event::Payout { staker: collator, amount: c_payout });
 			} else {
 				Self::deposit_event(Event::Unpaid { staker: collator, amount: c_payout });
@@ -1055,8 +1055,8 @@ type Vote = u32;
 
 type DepositId<T> = <<T as Config>::Deposit as Stake>::Item;
 
-/// Inflation and reward manager.
-pub trait InflationManager<T>
+/// Issuing and reward manager.
+pub trait IssuingManager<T>
 where
 	T: Config,
 {
@@ -1077,15 +1077,15 @@ where
 	}
 
 	/// Calculate the reward.
-	fn calculate_reward(inflation: Balance) -> Balance;
+	fn calculate_reward(issued: Balance) -> Balance;
 
 	/// The reward function.
 	fn reward(who: &T::AccountId, amount: Balance) -> DispatchResult;
 
 	/// Clear the remaining inflation.
 	fn clear(_remaining: Balance) {}
 }
-impl<T> InflationManager<T> for ()
+impl<T> IssuingManager<T> for ()
 where
 	T: Config,
 {
@@ -1191,7 +1191,7 @@ where
 	T: Config,
 {
 	fn end_session(_: u32) {
-		T::InflationManager::on_session_end();
+		T::IssuingManager::on_session_end();
 	}
 
 	fn start_session(_: u32) {}

pallet/staking/src/mock.rs

@@ -258,7 +258,7 @@ impl darwinia_staking::Stake for KtonStaking {
 	}
 }
 pub enum StatedOnSessionEnd {}
-impl darwinia_staking::InflationManager<Runtime> for StatedOnSessionEnd {
+impl darwinia_staking::IssuingManager<Runtime> for StatedOnSessionEnd {
 	fn inflate() -> Balance {
 		if INFLATION_TYPE.with(|v| *v.borrow()) == 0 {
 			OnDarwiniaSessionEnd::inflate()
@@ -267,11 +267,11 @@ impl darwinia_staking::InflationManager<Runtime> for StatedOnSessionEnd {
 		}
 	}
 
-	fn calculate_reward(inflation: Balance) -> Balance {
+	fn calculate_reward(issued: Balance) -> Balance {
 		if INFLATION_TYPE.with(|v| *v.borrow()) == 0 {
-			OnDarwiniaSessionEnd::calculate_reward(inflation)
+			OnDarwiniaSessionEnd::calculate_reward(issued)
 		} else {
-			OnCrabSessionEnd::calculate_reward(inflation)
+			OnCrabSessionEnd::calculate_reward(issued)
 		}
 	}
 
@@ -292,7 +292,7 @@ impl darwinia_staking::InflationManager<Runtime> for StatedOnSessionEnd {
 	}
 }
 pub enum OnDarwiniaSessionEnd {}
-impl darwinia_staking::InflationManager<Runtime> for OnDarwiniaSessionEnd {
+impl darwinia_staking::IssuingManager<Runtime> for OnDarwiniaSessionEnd {
 	fn inflate() -> Balance {
 		let now = Timestamp::now();
 		let session_duration = now - <darwinia_staking::SessionStartTime<Runtime>>::get();
@@ -304,13 +304,11 @@ impl darwinia_staking::InflationManager<Runtime> for OnDarwiniaSessionEnd {
 
 		<darwinia_staking::SessionStartTime<Runtime>>::put(now);
 
-		let unminted = dc_inflation::TOTAL_SUPPLY.saturating_sub(Balances::total_issuance());
-
-		dc_inflation::in_period(unminted, session_duration, elapsed_time).unwrap_or_default()
+		dc_inflation::issuing_in_period(session_duration, elapsed_time).unwrap_or_default()
 	}
 
-	fn calculate_reward(inflation: Balance) -> Balance {
-		PayoutFraction::get() * inflation
+	fn calculate_reward(issued: Balance) -> Balance {
+		PayoutFraction::get() * issued
 	}
 
 	fn reward(who: &AccountId, amount: Balance) -> sp_runtime::DispatchResult {
@@ -324,7 +322,7 @@ impl darwinia_staking::InflationManager<Runtime> for OnDarwiniaSessionEnd {
 	}
 }
 pub enum OnCrabSessionEnd {}
-impl darwinia_staking::InflationManager<Runtime> for OnCrabSessionEnd {
+impl darwinia_staking::IssuingManager<Runtime> for OnCrabSessionEnd {
 	fn calculate_reward(_inflation: Balance) -> Balance {
 		10_000 * UNIT
 	}
@@ -352,7 +350,7 @@ impl frame_support::traits::Get<bool> for ShouldEndSession {
 impl darwinia_staking::Config for Runtime {
 	type Currency = Balances;
 	type Deposit = Deposit;
-	type InflationManager = StatedOnSessionEnd;
+	type IssuingManager = StatedOnSessionEnd;
 	type Kton = KtonStaking;
 	type MaxDeposits = <Self as darwinia_deposit::Config>::MaxDeposits;
 	type MaxUnstakings = frame_support::traits::ConstU32<16>;