Add delay and maximum change rate for commission

node/src/parachain/dev_chain_spec.rs

@@ -12,7 +12,7 @@ use sp_consensus_aura::sr25519::AuthorityId as AuraId;
 use sp_core::{sr25519, Pair, Public};
 use sp_runtime::{
 	traits::{IdentifyAccount, Verify},
-	Perbill,
+	Perbill, Permill,
 };
 
 /// Specialized `ChainSpec`. This is a specialization of the general Substrate ChainSpec type.
@@ -133,6 +133,7 @@ fn configure_genesis(
 		parachain_staking: ParachainStakingConfig {
 			stakers,
 			max_candidate_stake: staking::MAX_COLLATOR_STAKE,
+			max_commission_change: Permill::from_percent(100),
 		},
 		inflation_manager: Default::default(),
 		block_reward: BlockRewardConfig {

node/src/parachain/krest_chain_spec.rs

@@ -9,7 +9,7 @@ use peaq_primitives_xcm::{AccountId, Balance};
 use runtime_common::TOKEN_DECIMALS;
 use sc_service::{ChainType, Properties};
 use sp_consensus_aura::sr25519::AuthorityId as AuraId;
-use sp_runtime::Perbill;
+use sp_runtime::{Perbill, Permill};
 
 use crate::parachain::dev_chain_spec::{authority_keys_from_seed, get_account_id_from_seed};
 
@@ -118,6 +118,7 @@ fn configure_genesis(
 		parachain_staking: ParachainStakingConfig {
 			stakers,
 			max_candidate_stake: staking::MAX_COLLATOR_STAKE,
+			max_commission_change: Permill::from_percent(100),
 		},
 		inflation_manager: Default::default(),
 		block_reward: BlockRewardConfig {

node/src/parachain/peaq_chain_spec.rs

@@ -9,7 +9,7 @@ use peaq_runtime::{
 use runtime_common::TOKEN_DECIMALS;
 use sc_service::{ChainType, Properties};
 use sp_consensus_aura::sr25519::AuthorityId as AuraId;
-use sp_runtime::Perbill;
+use sp_runtime::{Perbill, Permill};
 
 use crate::parachain::dev_chain_spec::{authority_keys_from_seed, get_account_id_from_seed};
 
@@ -122,6 +122,7 @@ fn configure_genesis(
 		parachain_staking: ParachainStakingConfig {
 			stakers,
 			max_candidate_stake: staking::MAX_COLLATOR_STAKE,
+			max_commission_change: Permill::from_percent(100),
 		},
 		inflation_manager: Default::default(),
 		block_reward: BlockRewardConfig {

pallets/parachain-staking/src/lib.rs

@@ -337,6 +337,10 @@ pub mod pallet {
 
 		/// Weight information for extrinsics in this pallet.
 		type WeightInfo: WeightInfo;
+
+		/// The minimum interval between two commission changes.
+		#[pallet::constant]
+		type CommissionChangeInterval: Get<BlockNumberFor<Self>>;
 	}
 
 	#[pallet::error]
@@ -432,6 +436,10 @@ pub mod pallet {
 		CommissionTooHigh,
 		/// Sudo cannot force new round if payouts are ongoing
 		PayoutsOngoing,
+		/// The commission change is too high.
+		CommissionChangeTooHigh,
+		/// The commission change is too frequent.
+		CommissionChangeTooEarly,
 	}
 
 	#[pallet::event]
@@ -519,6 +527,9 @@ pub mod pallet {
 		/// The commission for a collator has been changed.
 		/// \[collator's account, new commission\]
 		CollatorCommissionChanged(T::AccountId, Permill),
+		/// The commission maximum change has been changed.
+		/// \[new value\]
+		MaxCommissionChangeUpdated(Permill),
 	}
 
 	#[pallet::hooks]
@@ -677,15 +688,29 @@ pub mod pallet {
 	pub(crate) type DelayedPayoutInfo<T: Config> =
 		StorageValue<_, DelayedPayoutInfoT<SessionIndex, BalanceOf<T>>, OptionQuery>;
 
+	#[pallet::storage]
+	#[pallet::getter(fn last_commission_change)]
+	pub type LastCommissionChange<T: Config> =
+		StorageMap<_, Blake2_128Concat, T::AccountId, BlockNumberFor<T>, ValueQuery>;
+
+	#[pallet::storage]
+	#[pallet::getter(fn max_commission_change)]
+	pub type MaxCommissionChange<T> = StorageValue<_, Permill, ValueQuery>;
+
 	#[pallet::genesis_config]
 	pub struct GenesisConfig<T: Config> {
 		pub stakers: GenesisStaker<T>,
 		pub max_candidate_stake: BalanceOf<T>,
+		pub max_commission_change: Permill,
 	}
 
 	impl<T: Config> Default for GenesisConfig<T> {
 		fn default() -> Self {
-			Self { stakers: Default::default(), max_candidate_stake: Default::default() }
+			Self {
+				stakers: Default::default(),
+				max_candidate_stake: Default::default(),
+				max_commission_change: Permill::from_percent(100),
+			}
 		}
 	}
 
@@ -722,6 +747,8 @@ pub mod pallet {
 			let round: RoundInfo<BlockNumberFor<T>> =
 				RoundInfo::new(0u32, 0u32.into(), T::DefaultBlocksPerRound::get());
 			<Round<T>>::put(round);
+
+			MaxCommissionChange::<T>::put(self.max_commission_change);
 		}
 	}
 
@@ -1969,21 +1996,52 @@ pub mod pallet {
 		))]
 		pub fn set_commission(origin: OriginFor<T>, commission: Permill) -> DispatchResult {
 			let collator = ensure_signed(origin)?;
-			CandidatePool::<T>::get(&collator).ok_or(Error::<T>::CandidateNotFound)?;
-			if commission > Permill::from_percent(100) {
-				return Err(Error::<T>::CommissionTooHigh.into())
-			}
+			let current_block = <frame_system::Pallet<T>>::block_number();
 
-			<crate::pallet::CandidatePool<T>>::mutate(&collator, |maybe_candidate| {
-				if let Some(candidate) = maybe_candidate {
-					candidate.set_commission(commission);
-				}
-			});
+			// Check if the collator exists
+			let mut candidate =
+				CandidatePool::<T>::get(&collator).ok_or(Error::<T>::CandidateNotFound)?;
 
-			// Emit an event that the commission was updated.
-			Self::deposit_event(crate::pallet::Event::CollatorCommissionChanged(
-				collator, commission,
-			));
+			// Check the time since the last commission change
+			let last_change = LastCommissionChange::<T>::get(&collator);
+			ensure!(
+				current_block >= last_change + T::CommissionChangeInterval::get(),
+				Error::<T>::CommissionChangeTooEarly
+			);
+
+			// Check the maximum change commission
+			let max_change = MaxCommissionChange::<T>::get();
+			let current_commission = candidate.commission;
+			let change = if commission > current_commission {
+				commission - current_commission
+			} else {
+				current_commission - commission
+			};
+			ensure!(change <= max_change, Error::<T>::CommissionChangeTooHigh);
+
+			// Update the commission and the last change time
+			candidate.set_commission(commission);
+			CandidatePool::<T>::insert(&collator, candidate);
+			LastCommissionChange::<T>::insert(&collator, current_block);
+
+			// Emit an event that the commission was updated
+			Self::deposit_event(Event::CollatorCommissionChanged(collator, commission));
+			Ok(())
+		}
+
+		#[pallet::call_index(20)]
+		#[pallet::weight(<T as crate::pallet::Config>::WeightInfo::set_max_commission_change(
+		Permill::from_percent(100).deconstruct()
+		))]
+		pub fn set_max_commission_change(
+			origin: OriginFor<T>,
+			new_max_commission_change: Permill,
+		) -> DispatchResult {
+			ensure_root(origin)?;
+
+			MaxCommissionChange::<T>::put(new_max_commission_change);
+
+			Self::deposit_event(Event::MaxCommissionChangeUpdated(new_max_commission_change));
 			Ok(())
 		}
 	}

pallets/parachain-staking/src/migrations.rs

@@ -20,8 +20,9 @@ pub enum Versions {
 	_V8 = 8,
 	V9 = 9,
 	V10 = 10,
-	#[default]
 	V11 = 11,
+	#[default]
+	V12 = 12,
 }
 
 pub(crate) fn on_runtime_upgrade<T: Config>() -> Weight {
@@ -30,6 +31,8 @@ pub(crate) fn on_runtime_upgrade<T: Config>() -> Weight {
 
 mod upgrade {
 
+	use crate::MaxCommissionChange;
+
 	use super::*;
 
 	/// Migration implementation that deletes the old reward rate config and changes the staking ID.
@@ -102,6 +105,11 @@ mod upgrade {
 
 				log::info!("V11 Migrating Done.");
 			}
+
+			if onchain_storage_version < StorageVersion::new(Versions::V12 as u16) {
+				// Set the value of MaxCommissionChange to 10%
+				MaxCommissionChange::<T>::put(Permill::from_percent(10));
+			}
 			// update onchain storage version
 			StorageVersion::new(Versions::default() as u16).put::<Pallet<T>>();
 			weight_writes += 1;

pallets/parachain-staking/src/mock.rs

@@ -32,7 +32,7 @@ use sp_runtime::{
 	impl_opaque_keys,
 	testing::UintAuthorityId,
 	traits::{BlakeTwo256, ConvertInto, IdentityLookup, OpaqueKeys},
-	BuildStorage, Perbill,
+	BuildStorage, Perbill, Permill,
 };
 use sp_std::fmt::Debug;
 
@@ -154,6 +154,8 @@ parameter_types! {
 	pub const MinDelegatorStake: Balance = 5;
 	pub const MinDelegation: Balance = 3;
 	pub const MaxUnstakeRequests: u32 = 6;
+	pub const CommissionChangeInterval: BlockNumber = 1;
+
 }
 
 impl Config for Test {
@@ -177,6 +179,7 @@ impl Config for Test {
 	type MaxUnstakeRequests = MaxUnstakeRequests;
 	type PotId = PotId;
 	type WeightInfo = crate::weights::WeightInfo<Test>;
+	type CommissionChangeInterval = CommissionChangeInterval;
 }
 
 impl_opaque_keys! {
@@ -278,9 +281,13 @@ impl ExtBuilder {
 		for delegator in self.delegators.clone() {
 			stakers.push((delegator.0, Some(delegator.1), delegator.2));
 		}
-		stake::GenesisConfig::<Test> { stakers, max_candidate_stake: 160_000_000 * DECIMALS }
-			.assimilate_storage(&mut t)
-			.expect("Parachain Staking's storage can be assimilated");
+		stake::GenesisConfig::<Test> {
+			stakers,
+			max_candidate_stake: 160_000_000 * DECIMALS,
+			max_commission_change: Permill::from_percent(10),
+		}
+		.assimilate_storage(&mut t)
+		.expect("Parachain Staking's storage can be assimilated");
 
 		// stashes are the AccountId
 		let session_keys: Vec<_> = self

pallets/parachain-staking/src/tests.rs

@@ -3990,3 +3990,122 @@ fn check_snapshot_is_cleared() {
 			assert_eq!(at_stake.len(), 0);
 		});
 }
+
+#[test]
+fn change_commission_too_frequently() {
+	ExtBuilder::default()
+		.with_balances(vec![(1, 1000), (2, 1000), (3, 1000)])
+		.with_collators(vec![(1, 500)])
+		.with_delegators(vec![(2, 1, 600), (3, 1, 400)])
+		.build()
+		.execute_with(|| {
+			assert!(System::events().is_empty());
+
+			assert_ok!(Balances::force_set_balance(
+				RawOrigin::Root.into(),
+				StakePallet::account_id(),
+				1000,
+			));
+
+			assert_ok!(StakePallet::set_commission(
+				RuntimeOrigin::signed(1),
+				Permill::from_percent(10)
+			));
+			let state = CandidatePool::<Test>::get(1).unwrap();
+			assert_eq!(state.commission, Permill::from_percent(10));
+			assert_eq!(
+				StakePallet::candidate_pool(1).unwrap().commission,
+				Permill::from_percent(10)
+			);
+
+			// change commission too frequently
+			assert_noop!(
+				StakePallet::set_commission(RuntimeOrigin::signed(1), Permill::from_percent(20)),
+				Error::<Test>::CommissionChangeTooEarly
+			);
+			// change commission too frequently
+			assert_noop!(
+				StakePallet::set_commission(RuntimeOrigin::signed(1), Permill::from_percent(30)),
+				Error::<Test>::CommissionChangeTooEarly
+			);
+		});
+}
+
+#[test]
+fn change_commission_after_while() {
+	ExtBuilder::default()
+		.with_balances(vec![(1, 1000), (2, 1000), (3, 1000)])
+		.with_collators(vec![(1, 500)])
+		.with_delegators(vec![(2, 1, 600), (3, 1, 400)])
+		.build()
+		.execute_with(|| {
+			assert!(System::events().is_empty());
+
+			assert_ok!(Balances::force_set_balance(
+				RawOrigin::Root.into(),
+				StakePallet::account_id(),
+				1000,
+			));
+
+			assert_ok!(StakePallet::set_commission(
+				RuntimeOrigin::signed(1),
+				Permill::from_percent(10)
+			));
+			let state = CandidatePool::<Test>::get(1).unwrap();
+			assert_eq!(state.commission, Permill::from_percent(10));
+			assert_eq!(
+				StakePallet::candidate_pool(1).unwrap().commission,
+				Permill::from_percent(10)
+			);
+
+			// change commission after a while
+			roll_to(10, vec![]);
+			assert_ok!(StakePallet::set_commission(
+				RuntimeOrigin::signed(1),
+				Permill::from_percent(20)
+			));
+			let state = CandidatePool::<Test>::get(1).unwrap();
+			assert_eq!(state.commission, Permill::from_percent(20));
+			assert_eq!(
+				StakePallet::candidate_pool(1).unwrap().commission,
+				Permill::from_percent(20)
+			);
+		});
+}
+
+#[test]
+fn change_commission_by_too_much() {
+	ExtBuilder::default()
+		.with_balances(vec![(1, 1000), (2, 1000), (3, 1000)])
+		.with_collators(vec![(1, 500)])
+		.with_delegators(vec![(2, 1, 600), (3, 1, 400)])
+		.build()
+		.execute_with(|| {
+			assert!(System::events().is_empty());
+
+			assert_ok!(Balances::force_set_balance(
+				RawOrigin::Root.into(),
+				StakePallet::account_id(),
+				1000,
+			));
+
+			assert_ok!(StakePallet::set_commission(
+				RuntimeOrigin::signed(1),
+				Permill::from_percent(10)
+			));
+			let state = CandidatePool::<Test>::get(1).unwrap();
+			assert_eq!(state.commission, Permill::from_percent(10));
+			assert_eq!(
+				StakePallet::candidate_pool(1).unwrap().commission,
+				Permill::from_percent(10)
+			);
+
+			roll_to(10, vec![]);
+
+			// change commission by too much
+			assert_noop!(
+				StakePallet::set_commission(RuntimeOrigin::signed(1), Permill::from_percent(30)),
+				Error::<Test>::CommissionChangeTooHigh
+			);
+		});
+}

pallets/parachain-staking/src/weightinfo.rs

@@ -24,4 +24,5 @@ pub trait WeightInfo {
 	fn unlock_unstaked(u: u32) -> Weight;
 	fn set_max_candidate_stake() -> Weight;
 	fn set_commission(n: u32, m: u32) -> Weight;
+	fn set_max_commission_change(n: u32) -> Weight;
 }