Minimum commission for validators (#10347)

* Minimum commission for validators

* rename

* Fix benchmakrs

* cargo run --quiet --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_staking --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/staking/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* Update frame/staking/src/pallet/mod.rs

* cargo run --quiet --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_staking --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/staking/src/weights.rs --template=./.maintain/frame-weight-template.hbs

Co-authored-by: Parity Bot <admin@parity.io>
Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

substrate/frame/staking/src/pallet/mod.rs

@@ -215,6 +215,12 @@ pub mod pallet {
 	#[pallet::storage]
 	pub type MinValidatorBond<T: Config> = StorageValue<_, BalanceOf<T>, ValueQuery>;
 
+	/// The minimum amount of commission that validators can set.
+	///
+	/// If set to `0`, 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)]
@@ -486,6 +492,8 @@ 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")]
@@ -502,6 +510,8 @@ pub mod pallet {
 				stakers: Default::default(),
 				min_nominator_bond: Default::default(),
 				min_validator_bond: Default::default(),
+				max_validator_count: None,
+				max_nominator_count: None,
 			}
 		}
 	}
@@ -519,6 +529,12 @@ 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!(
@@ -650,6 +666,8 @@ 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]
@@ -955,9 +973,13 @@ 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
@@ -1508,7 +1530,7 @@ 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.
@@ -1516,26 +1538,32 @@ pub mod pallet {
 		///   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(())
 		}