Adjust to new Broker pallet. (#334)

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---------

Co-authored-by: eskimor <eskimor@no-such-url.com>
Co-authored-by: Dónal Murray <donalm@seadanda.dev>

Author: 3 people

CHANGELOG.md

@@ -10,6 +10,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 - Staking runtime api to check if reward is pending for an era ([polkadot-fellows/runtimes#318](https://github.com/polkadot-fellows/runtimes/pull/318))
 - Allow any parachain to have bidirectional channel with any system parachains ([polkadot-fellows/runtimes#329](https://github.com/polkadot-fellows/runtimes/pull/329))
+- Update price controller of broker pallet to use higher leadin, without adjusting the minimum price too much ([polkadot-fellows/runtimes#334](https://github.com/polkadot-fellows/runtimes/pull/334)
 - Enable support for new hardware signers like the generic ledger app ([polkadot-fellows/runtimes#337](https://github.com/polkadot-fellows/runtimes/pull/337))
 
 ### Changed

Cargo.lock

@@ -97,7 +97,7 @@ pallet-bridge-grandpa = { version = "0.8.0", default-features = false }
 pallet-bridge-messages = { version = "0.8.0", default-features = false }
 pallet-bridge-parachains = { version = "0.8.0", default-features = false }
 pallet-bridge-relayers = { version = "0.8.0", default-features = false }
-pallet-broker = { version = "0.7.1", default-features = false }
+pallet-broker = { version = "0.7.2", default-features = false }
 pallet-child-bounties = { version = "28.0.0", default-features = false }
 pallet-collator-selection = { version = "10.0.2", default-features = false }
 pallet-collective = { version = "29.0.0", default-features = false }

Cargo.toml

@@ -25,13 +25,8 @@ use frame_support::{
 		OnUnbalanced,
 	},
 };
-use pallet_broker::{
-	AdaptPrice, CoreAssignment, CoreIndex, CoretimeInterface, PartsOf57600, RCBlockNumberOf,
-};
-use sp_runtime::{
-	traits::{AccountIdConversion, One, Saturating},
-	FixedU64,
-};
+use pallet_broker::{CoreAssignment, CoreIndex, CoretimeInterface, PartsOf57600, RCBlockNumberOf};
+use sp_runtime::traits::AccountIdConversion;
 use xcm::latest::prelude::*;
 
 /// A type containing the encoding of the coretime pallet in the Relay chain runtime. Used to
@@ -200,40 +195,6 @@ impl CoretimeInterface for CoretimeAllocator {
 	}
 }
 
-/// Implements the [`AdaptPrice`] trait to control the price changes of bulk coretime. This tweaks
-/// the [`pallet_broker::Linear`] implementation which hard-corrects to 0 if cores are offered but
-/// not sold for just one sale. The monotonic lead-in is increased in magnitude to enable faster
-/// price finding. The change in base price between sales has a lower limit of 0.5 to allow downward
-/// pressure to be applied, while keeping a conservative upper limit of 1.2 (movements capped at 20%
-/// if cores sell out) to avoid runaway prices in the early sales. The intention is that this will
-/// be coupled with a low number of cores per sale and a 100% ideal bulk ratio for the first sales.
-pub struct PriceAdapter;
-impl AdaptPrice for PriceAdapter {
-	fn leadin_factor_at(when: FixedU64) -> FixedU64 {
-		// Start at 5x the base price and decrease to the base price at the end of leadin.
-		FixedU64::from(5).saturating_sub(FixedU64::from(4) * when)
-	}
-
-	fn adapt_price(sold: CoreIndex, target: CoreIndex, limit: CoreIndex) -> FixedU64 {
-		if sold <= target {
-			// Range of [0.5, 1.0].
-			FixedU64::from_rational(1, 2).saturating_add(FixedU64::from_rational(
-				(sold).into(),
-				(target.saturating_mul(2)).into(),
-			))
-		} else {
-			// Range of (1.0, 1.2].
-
-			// Unchecked math: In this branch we know that sold > target. The limit must be >= sold
-			// by construction, and thus target must be < limit.
-			FixedU64::one().saturating_add(FixedU64::from_rational(
-				(sold - target).into(),
-				(limit - target).saturating_mul(5).into(),
-			))
-		}
-	}
-}
-
 parameter_types! {
 	pub const BrokerPalletId: PalletId = PalletId(*b"py/broke");
 }
@@ -253,8 +214,5 @@ impl pallet_broker::Config for Runtime {
 	type WeightInfo = weights::pallet_broker::WeightInfo<Runtime>;
 	type PalletId = BrokerPalletId;
 	type AdminOrigin = EnsureRoot<AccountId>;
-	#[cfg(feature = "runtime-benchmarks")]
-	type PriceAdapter = pallet_broker::Linear;
-	#[cfg(not(feature = "runtime-benchmarks"))]
-	type PriceAdapter = PriceAdapter;
+	type PriceAdapter = pallet_broker::CenterTargetPrice<Balance>;
 }

system-parachains/coretime/coretime-kusama/src/coretime.rs

@@ -15,7 +15,7 @@
 // limitations under the License.
 
 use crate::{
-	coretime::{BrokerPalletId, CoretimeBurnAccount, PriceAdapter},
+	coretime::{BrokerPalletId, CoretimeBurnAccount},
 	*,
 };
 use frame_support::{
@@ -25,61 +25,9 @@ use frame_support::{
 		OnInitialize,
 	},
 };
-use pallet_broker::{AdaptPrice, ConfigRecordOf, SaleInfo};
+use pallet_broker::{ConfigRecordOf, SaleInfo};
 use parachains_runtimes_test_utils::ExtBuilder;
-use sp_runtime::{
-	traits::{AccountIdConversion, One},
-	FixedU64,
-};
-
-#[test]
-fn adapt_price_no_panic() {
-	for limit in 0..10 {
-		for target in 1..10 {
-			for sold in 0..=limit {
-				let price = PriceAdapter::adapt_price(sold, target, limit);
-
-				if sold > target {
-					assert!(price > FixedU64::one());
-				} else {
-					assert!(price <= FixedU64::one());
-				}
-			}
-		}
-	}
-}
-
-#[test]
-fn adapt_price_bound_check() {
-	// Using assumptions from pallet implementation i.e. `limit >= sold`.
-	// Check extremes
-	let limit = 10;
-	let target = 5;
-
-	// Maximally sold: `sold == limit`
-	assert_eq!(PriceAdapter::adapt_price(limit, target, limit), FixedU64::from_float(1.2));
-	// Ideally sold: `sold == target`
-	assert_eq!(PriceAdapter::adapt_price(target, target, limit), FixedU64::one());
-	// Minimally sold: `sold == 0`
-	assert_eq!(PriceAdapter::adapt_price(0, target, limit), FixedU64::from_float(0.5));
-	// Optimistic target: `target == limit`
-	assert_eq!(PriceAdapter::adapt_price(limit, limit, limit), FixedU64::one());
-	// Pessimistic target: `target == 0`
-	assert_eq!(PriceAdapter::adapt_price(limit, 0, limit), FixedU64::from_float(1.2));
-}
-
-#[test]
-fn leadin_price_bound_check() {
-	// Using assumptions from pallet implementation i.e. `when` in range [0, 1].
-	// Linear, therefore we need three points to fully test it
-
-	// Start of leadin: 5x
-	assert_eq!(PriceAdapter::leadin_factor_at(FixedU64::from(0)), FixedU64::from(5));
-	// Midway through leadin: 3x
-	assert_eq!(PriceAdapter::leadin_factor_at(FixedU64::from_float(0.5)), FixedU64::from(3));
-	// End of leadin: 1x
-	assert_eq!(PriceAdapter::leadin_factor_at(FixedU64::one()), FixedU64::one());
-}
+use sp_runtime::traits::AccountIdConversion;
 
 fn advance_to(b: BlockNumber) {
 	while System::block_number() < b {
@@ -124,14 +72,14 @@ fn bulk_revenue_is_burnt() {
 			let broker_account = BrokerPalletId::get().into_account_truncating();
 			let coretime_burn_account = CoretimeBurnAccount::get();
 			let treasury_account = xcm_config::RelayTreasuryPalletAccount::get();
-			assert_ok!(Balances::mint_into(&AccountId::from(ALICE), 10 * ed));
+			assert_ok!(Balances::mint_into(&AccountId::from(ALICE), 200 * ed));
 			let alice_balance_before = Balances::balance(&AccountId::from(ALICE));
 			let treasury_balance_before = Balances::balance(&treasury_account);
 			let broker_balance_before = Balances::balance(&broker_account);
 			let burn_balance_before = Balances::balance(&coretime_burn_account);
 
 			// Purchase coretime.
-			assert_ok!(Broker::purchase(RuntimeOrigin::signed(AccountId::from(ALICE)), 5 * ed));
+			assert_ok!(Broker::purchase(RuntimeOrigin::signed(AccountId::from(ALICE)), 100 * ed));
 
 			// Alice decreases.
 			assert!(Balances::balance(&AccountId::from(ALICE)) < alice_balance_before);