Allow configuration option for minimum commission of validators

frame/staking/src/benchmarking.rs

@@ -841,21 +841,23 @@ benchmarks! {
 		assert_eq!(targets.len() as u32, v);
 	}
 
-	set_staking_limits {
+	set_staking_configs {
 		// This function always does the same thing... just write to 4 storage items.
 	}: _(
 		RawOrigin::Root,
 		BalanceOf::<T>::max_value(),
 		BalanceOf::<T>::max_value(),
 		Some(u32::MAX),
 		Some(u32::MAX),
-		Some(Percent::max_value())
+		Some(Percent::max_value()),
+		Perbill::max_value()
 	) verify {
 		assert_eq!(MinNominatorBond::<T>::get(), BalanceOf::<T>::max_value());
 		assert_eq!(MinValidatorBond::<T>::get(), BalanceOf::<T>::max_value());
 		assert_eq!(MaxNominatorsCount::<T>::get(), Some(u32::MAX));
 		assert_eq!(MaxValidatorsCount::<T>::get(), Some(u32::MAX));
 		assert_eq!(ChillThreshold::<T>::get(), Some(Percent::from_percent(100)));
+		assert_eq!(MinCommission::<T>::get(), Perbill::from_percent(100));
 	}
 
 	chill_other {
@@ -871,13 +873,14 @@ benchmarks! {
 		let stash = scenario.origin_stash1.clone();
 		assert!(T::SortedListProvider::contains(&stash));
 
-		Staking::<T>::set_staking_limits(
+		Staking::<T>::set_staking_configs(
 			RawOrigin::Root.into(),
 			BalanceOf::<T>::max_value(),
 			BalanceOf::<T>::max_value(),
 			Some(0),
 			Some(0),
-			Some(Percent::from_percent(0))
+			Some(Percent::from_percent(0)),
+			Zero::zero(),
 		)?;
 
 		let caller = whitelisted_caller();

frame/staking/src/pallet/mod.rs

@@ -210,6 +210,12 @@ pub mod pallet {
 	#[pallet::storage]
 	pub type MinValidatorBond<T: Config> = StorageValue<_, BalanceOf<T>, ValueQuery>;
 
+	/// The minimum amount of commission that validators can set.
+	///
+	/// If non-existent, no limit exists.
+	#[pallet::storage]
+	pub type MinCommission<T: Config> = StorageValue<_, Perbill, ValueQuery>;
+
 	/// Map from all (unlocked) "controller" accounts to the info regarding the staking.
 	#[pallet::storage]
 	#[pallet::getter(fn ledger)]
@@ -481,6 +487,8 @@ pub mod pallet {
 			Vec<(T::AccountId, T::AccountId, BalanceOf<T>, crate::StakerStatus<T::AccountId>)>,
 		pub min_nominator_bond: BalanceOf<T>,
 		pub min_validator_bond: BalanceOf<T>,
+		pub max_validator_count: Option<u32>,
+		pub max_nominator_count: Option<u32>,
 	}
 
 	#[cfg(feature = "std")]
@@ -497,6 +505,8 @@ pub mod pallet {
 				stakers: Default::default(),
 				min_nominator_bond: Default::default(),
 				min_validator_bond: Default::default(),
+				max_validator_count: None,
+				max_nominator_count: None,
 			}
 		}
 	}
@@ -514,6 +524,12 @@ pub mod pallet {
 			StorageVersion::<T>::put(Releases::V7_0_0);
 			MinNominatorBond::<T>::put(self.min_nominator_bond);
 			MinValidatorBond::<T>::put(self.min_validator_bond);
+			if let Some(x) = self.max_validator_count {
+				MaxValidatorsCount::<T>::put(x);
+			}
+			if let Some(x) = self.max_nominator_count {
+				MaxNominatorsCount::<T>::put(x);
+			}
 
 			for &(ref stash, ref controller, balance, ref status) in &self.stakers {
 				log!(
@@ -645,6 +661,8 @@ pub mod pallet {
 		/// There are too many validators in the system. Governance needs to adjust the staking
 		/// settings to keep things safe for the runtime.
 		TooManyValidators,
+		/// Commission is too low. Must be at least `MinCommission`.
+		CommissionTooLow,
 	}
 
 	#[pallet::hooks]
@@ -950,9 +968,13 @@ pub mod pallet {
 			let controller = ensure_signed(origin)?;
 
 			let ledger = Self::ledger(&controller).ok_or(Error::<T>::NotController)?;
+
 			ensure!(ledger.active >= MinValidatorBond::<T>::get(), Error::<T>::InsufficientBond);
 			let stash = &ledger.stash;
 
+			// ensure their commission is correct.
+			ensure!(prefs.commission >= MinCommission::<T>::get(), Error::<T>::CommissionTooLow);
+
 			// Only check limits if they are not already a validator.
 			if !Validators::<T>::contains_key(stash) {
 				// If this error is reached, we need to adjust the `MinValidatorBond` and start
@@ -1503,34 +1525,40 @@ pub mod pallet {
 			Ok(())
 		}
 
-		/// Update the various staking limits this pallet.
+		/// Update the various staking configurations .
 		///
 		/// * `min_nominator_bond`: The minimum active bond needed to be a nominator.
 		/// * `min_validator_bond`: The minimum active bond needed to be a validator.
 		/// * `max_nominator_count`: The max number of users who can be a nominator at once. When
 		///   set to `None`, no limit is enforced.
 		/// * `max_validator_count`: The max number of users who can be a validator at once. When
 		///   set to `None`, no limit is enforced.
+		/// * `chill_threshold`: The ratio of `max_nominator_count` or `max_validator_count` which
+		///   should be filled in order for the `chill_other` transaction to work.
+		/// * `min_commission`: The minimum amount of commission that each validators must maintain.
+		///   This is checked only upon calling `validate`. Existing validators are not affected.
 		///
 		/// Origin must be Root to call this function.
 		///
 		/// NOTE: Existing nominators and validators will not be affected by this update.
 		/// to kick people under the new limits, `chill_other` should be called.
-		#[pallet::weight(T::WeightInfo::set_staking_limits())]
-		pub fn set_staking_limits(
+		#[pallet::weight(T::WeightInfo::set_staking_configs())]
+		pub fn set_staking_configs(
 			origin: OriginFor<T>,
 			min_nominator_bond: BalanceOf<T>,
 			min_validator_bond: BalanceOf<T>,
 			max_nominator_count: Option<u32>,
 			max_validator_count: Option<u32>,
-			threshold: Option<Percent>,
+			chill_threshold: Option<Percent>,
+			min_commission: Perbill,
 		) -> DispatchResult {
 			ensure_root(origin)?;
 			MinNominatorBond::<T>::set(min_nominator_bond);
 			MinValidatorBond::<T>::set(min_validator_bond);
 			MaxNominatorsCount::<T>::set(max_nominator_count);
 			MaxValidatorsCount::<T>::set(max_validator_count);
-			ChillThreshold::<T>::set(threshold);
+			ChillThreshold::<T>::set(chill_threshold);
+			MinCommission::<T>::set(min_commission);
 			Ok(())
 		}
 

frame/staking/src/tests.rs

@@ -4350,7 +4350,15 @@ fn chill_other_works() {
 			);
 
 			// Change the minimum bond... but no limits.
-			assert_ok!(Staking::set_staking_limits(Origin::root(), 1_500, 2_000, None, None, None));
+			assert_ok!(Staking::set_staking_configs(
+				Origin::root(),
+				1_500,
+				2_000,
+				None,
+				None,
+				None,
+				Zero::zero()
+			));
 
 			// Still can't chill these users
 			assert_noop!(
@@ -4363,13 +4371,14 @@ fn chill_other_works() {
 			);
 
 			// Add limits, but no threshold
-			assert_ok!(Staking::set_staking_limits(
+			assert_ok!(Staking::set_staking_configs(
 				Origin::root(),
 				1_500,
 				2_000,
 				Some(10),
 				Some(10),
-				None
+				None,
+				Zero::zero()
 			));
 
 			// Still can't chill these users
@@ -4383,13 +4392,14 @@ fn chill_other_works() {
 			);
 
 			// Add threshold, but no limits
-			assert_ok!(Staking::set_staking_limits(
+			assert_ok!(Staking::set_staking_configs(
 				Origin::root(),
 				1_500,
 				2_000,
 				None,
 				None,
-				Some(Percent::from_percent(0))
+				Some(Percent::from_percent(0)),
+				Zero::zero()
 			));
 
 			// Still can't chill these users
@@ -4403,13 +4413,14 @@ fn chill_other_works() {
 			);
 
 			// Add threshold and limits
-			assert_ok!(Staking::set_staking_limits(
+			assert_ok!(Staking::set_staking_configs(
 				Origin::root(),
 				1_500,
 				2_000,
 				Some(10),
 				Some(10),
-				Some(Percent::from_percent(75))
+				Some(Percent::from_percent(75)),
+				Zero::zero()
 			));
 
 			// 16 people total because tests start with 2 active one
@@ -4447,13 +4458,14 @@ fn capped_stakers_works() {
 
 		// Change the maximums
 		let max = 10;
-		assert_ok!(Staking::set_staking_limits(
+		assert_ok!(Staking::set_staking_configs(
 			Origin::root(),
 			10,
 			10,
 			Some(max),
 			Some(max),
-			Some(Percent::from_percent(0))
+			Some(Percent::from_percent(0)),
+			Zero::zero(),
 		));
 
 		// can create `max - validator_count` validators
@@ -4516,12 +4528,60 @@ fn capped_stakers_works() {
 		));
 
 		// No problem when we set to `None` again
-		assert_ok!(Staking::set_staking_limits(Origin::root(), 10, 10, None, None, None));
+		assert_ok!(Staking::set_staking_configs(
+			Origin::root(),
+			10,
+			10,
+			None,
+			None,
+			None,
+			Zero::zero(),
+		));
 		assert_ok!(Staking::nominate(Origin::signed(last_nominator), vec![1]));
 		assert_ok!(Staking::validate(Origin::signed(last_validator), ValidatorPrefs::default()));
 	})
 }
 
+#[test]
+fn min_commission_works() {
+	ExtBuilder::default().build_and_execute(|| {
+		assert_ok!(Staking::validate(
+			Origin::signed(10),
+			ValidatorPrefs { commission: Perbill::from_percent(5), blocked: false }
+		));
+
+		assert_ok!(Staking::set_staking_configs(
+			Origin::root(),
+			0,
+			0,
+			None,
+			None,
+			None,
+			Perbill::from_percent(10),
+		));
+
+		// can't make it less than 10 now
+		assert_noop!(
+			Staking::validate(
+				Origin::signed(10),
+				ValidatorPrefs { commission: Perbill::from_percent(5), blocked: false }
+			),
+			Error::<Test>::CommissionTooLow
+		);
+
+		// can only change to higher.
+		assert_ok!(Staking::validate(
+			Origin::signed(10),
+			ValidatorPrefs { commission: Perbill::from_percent(10), blocked: false }
+		));
+
+		assert_ok!(Staking::validate(
+			Origin::signed(10),
+			ValidatorPrefs { commission: Perbill::from_percent(15), blocked: false }
+		));
+	})
+}
+
 mod sorted_list_provider {
 	use super::*;
 	use frame_election_provider_support::SortedListProvider;