pallet-staking: Add extrinsic force_apply_min_commission

frame/staking/src/benchmarking.rs

@@ -900,6 +900,27 @@ benchmarks! {
 		assert!(!T::SortedListProvider::contains(&stash));
 	}
 
+	force_apply_min_commission {
+		let i in 1..MaxValidators::<T>::get();
+		// Clean up any existing state
+		clear_validators_and_nominators::<T>();
+
+		// Create `i` validators with a commission of 50%
+		frame_support::assert_ok!(create_validators::<T>(i, 1));
+
+		// Sanity check that all the generated validators have the expected commission
+		for (_, prefs) in Validators::<T>::iter() {
+			assert_eq!(prefs.commission, Perbill::from_percent(50));
+		}
+		// Set the min commission to 75%
+		MinCommission::<T>::set(Perbill::from_percent(75));
+	}: _(RawOrigin::Root, 0)
+	verify {
+		for (_, prefs) in Validators::<T>::iter() {
+			assert_eq!(prefs.commission, Perbill::from_percent(75));
+		}
+	}
+
 	impl_benchmark_test_suite!(
 		Staking,
 		crate::mock::ExtBuilder::default().has_stakers(true),

frame/staking/src/pallet/mod.rs

@@ -1616,6 +1616,28 @@ pub mod pallet {
 			Self::chill_stash(&stash);
 			Ok(())
 		}
+
+		/// Force all validators to have at least the minimum commission. This will not affect
+		/// validators who already have a commission greater than or equal to the minimum.
+		///
+		/// Note that parameter `_validator_count` should be the upper bound of the number of
+		/// validators stored and is only used for weights.
+		#[pallet::weight(T::WeightInfo::force_apply_min_commission(*_validator_count))]
+		pub fn force_apply_min_commission(
+			origin: OriginFor<T>,
+			_validator_count: u32,
+		) -> DispatchResult {
+			ensure_root(origin)?;
+			let min_commission = MinCommission::<T>::get();
+			Validators::<T>::translate(|_, mut prefs: ValidatorPrefs| {
+				if prefs.commission < min_commission {
+					prefs.commission = min_commission
+				}
+
+				Some(prefs)
+			});
+			Ok(())
+		}
 	}
 }
 

frame/staking/src/tests.rs

@@ -4711,3 +4711,39 @@ mod sorted_list_provider {
 		});
 	}
 }
+
+#[test]
+fn force_apply_min_commission_works() {
+	let prefs = |c| ValidatorPrefs { commission: Perbill::from_percent(c), blocked: false };
+	let validators = || Validators::<Test>::iter().collect::<Vec<_>>();
+	ExtBuilder::default().build_and_execute(|| {
+		// Given all validators have a commission of 0
+		assert_eq!(validators(), vec![(31, prefs(0)), (21, prefs(0)), (11, prefs(0))]);
+		// and the min commission is 0
+		assert_eq!(MinCommission::<Test>::get(), Perbill::from_percent(0));
+
+		// When
+		assert_ok!(Staking::force_apply_min_commission(Origin::root(), 0));
+
+		// Then
+		assert_eq!(validators(), vec![(31, prefs(0)), (21, prefs(0)), (11, prefs(0))]);
+
+		// Given
+		assert_ok!(Staking::validate(Origin::signed(30), prefs(10)));
+
+		// When
+		assert_ok!(Staking::force_apply_min_commission(Origin::root(), 0));
+
+		// Then
+		assert_eq!(validators(), vec![(31, prefs(10)), (21, prefs(0)), (11, prefs(0))]);
+
+		// Given
+		MinCommission::<Test>::set(Perbill::from_percent(5));
+
+		// When
+		assert_ok!(Staking::force_apply_min_commission(Origin::root(), 0));
+
+		// Then
+		assert_eq!(validators(), vec![(31, prefs(10)), (21, prefs(5)), (11, prefs(5))]);
+	});
+}