Able to chill inactive validator

polkadot/runtime/westend/src/weights/pallet_staking.rs

@@ -826,4 +826,8 @@ impl<T: frame_system::Config> pallet_staking::WeightInfo for WeightInfo<T> {
 			.saturating_add(T::DbWeight::get().reads(5))
 			.saturating_add(T::DbWeight::get().writes(4))
 	}
+	// TODO: benchmark.
+	fn chill_inactive_validator(l: u32, ) -> Weight {
+		0.into()
+	}
 }

substrate/frame/staking/src/benchmarking.rs

@@ -336,7 +336,7 @@ mod benchmarks {
 
 		let origin_weight = MinNominatorBond::<T>::get().max(asset::existential_deposit::<T>());
 
-		// setup a worst case list scenario. Note that we don't care about the setup of the
+		// Setup a worst case list scenario. Note that we don't care about the setup of the
 		// destination position because we are doing a removal from the list but no insert.
 		let scenario = ListScenario::<T>::new(origin_weight, true)?;
 		let controller = scenario.origin_controller1.clone();
@@ -461,7 +461,7 @@ mod benchmarks {
 
 		let origin_weight = MinNominatorBond::<T>::get().max(asset::existential_deposit::<T>());
 
-		// setup a worst case list scenario. Note we don't care about the destination position,
+		// Setup a worst case list scenario. Note we don't care about the destination position,
 		// because we are just doing an insert into the origin position.
 		ListScenario::<T>::new(origin_weight, true)?;
 		let (stash, controller) = create_stash_controller_with_balance::<T>(
@@ -494,7 +494,7 @@ mod benchmarks {
 
 		let origin_weight = MinNominatorBond::<T>::get().max(asset::existential_deposit::<T>());
 
-		// setup a worst case list scenario. Note that we don't care about the setup of the
+		// Setup a worst case list scenario. Note that we don't care about the setup of the
 		// destination position because we are doing a removal from the list but no insert.
 		let scenario = ListScenario::<T>::new(origin_weight, true)?;
 		let controller = scenario.origin_controller1.clone();
@@ -655,7 +655,7 @@ mod benchmarks {
 
 		let origin_weight = MinNominatorBond::<T>::get().max(asset::existential_deposit::<T>());
 
-		// setup a worst case list scenario. Note that we don't care about the setup of the
+		// Setup a worst case list scenario. Note that we don't care about the setup of the
 		// destination position because we are doing a removal from the list but no insert.
 		let scenario = ListScenario::<T>::new(origin_weight, true)?;
 		let controller = scenario.origin_controller1.clone();
@@ -749,7 +749,7 @@ mod benchmarks {
 			// we use 100 to play friendly with the list threshold values in the mock
 			.max(100u32.into());
 
-		// setup a worst case list scenario.
+		// Setup a worst case list scenario.
 		let scenario = ListScenario::<T>::new(origin_weight, true)?;
 		let dest_weight = scenario.dest_weight;
 
@@ -793,7 +793,7 @@ mod benchmarks {
 
 		let origin_weight = MinNominatorBond::<T>::get().max(asset::existential_deposit::<T>());
 
-		// setup a worst case list scenario. Note that we don't care about the setup of the
+		// Setup a worst case list scenario. Note that we don't care about the setup of the
 		// destination position because we are doing a removal from the list but no insert.
 		let scenario = ListScenario::<T>::new(origin_weight, true)?;
 		let controller = scenario.origin_controller1.clone();
@@ -1006,6 +1006,7 @@ mod benchmarks {
 			ConfigOp::Set(u32::MAX),
 			ConfigOp::Set(u32::MAX),
 			ConfigOp::Set(Percent::max_value()),
+			ConfigOp::Set(T::HistoryDepth::get()),
 			ConfigOp::Set(Perbill::max_value()),
 			ConfigOp::Set(Percent::max_value()),
 		);
@@ -1015,6 +1016,7 @@ mod benchmarks {
 		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!(ChillInactiveValidatorThreshold::<T>::get(), T::HistoryDepth::get());
 		assert_eq!(MinCommission::<T>::get(), Perbill::from_percent(100));
 		assert_eq!(MaxStakedRewards::<T>::get(), Some(Percent::from_percent(100)));
 	}
@@ -1031,6 +1033,7 @@ mod benchmarks {
 			ConfigOp::Remove,
 			ConfigOp::Remove,
 			ConfigOp::Remove,
+			ConfigOp::Remove,
 		);
 
 		assert!(!MinNominatorBond::<T>::exists());
@@ -1049,7 +1052,7 @@ mod benchmarks {
 
 		let origin_weight = MinNominatorBond::<T>::get().max(asset::existential_deposit::<T>());
 
-		// setup a worst case list scenario. Note that we don't care about the setup of the
+		// Setup a worst case list scenario. Note that we don't care about the setup of the
 		// destination position because we are doing a removal from the list but no insert.
 		let scenario = ListScenario::<T>::new(origin_weight, true)?;
 		let stash = scenario.origin_stash1;
@@ -1062,6 +1065,7 @@ mod benchmarks {
 			ConfigOp::Set(0),
 			ConfigOp::Set(0),
 			ConfigOp::Set(Percent::from_percent(0)),
+			ConfigOp::Set(2),
 			ConfigOp::Set(Zero::zero()),
 			ConfigOp::Noop,
 		)?;
@@ -1133,6 +1137,56 @@ mod benchmarks {
 		Ok(())
 	}
 
+	#[benchmark]
+	fn chill_inactive_validator(
+		l: Linear<2, { ChillInactiveValidatorThreshold::<T>::get() }>,
+	) -> Result<(), BenchmarkError> {
+		let (stash, _) = create_validator_with_nominators::<T>(
+			0,
+			0,
+			false,
+			true,
+			RewardDestination::Staked,
+		)?;
+		assert!(T::VoterList::contains(&stash));
+
+		Staking::<T>::set_staking_configs(
+			RawOrigin::Root.into(),
+			ConfigOp::Set(BalanceOf::<T>::max_value()),
+			ConfigOp::Set(BalanceOf::<T>::max_value()),
+			ConfigOp::Set(0),
+			ConfigOp::Set(0),
+			ConfigOp::Set(Percent::from_percent(0)),
+			ConfigOp::Set(l),
+			ConfigOp::Set(Zero::zero()),
+			ConfigOp::Noop,
+		)?;
+
+		let caller = whitelisted_caller();
+		// Set the validator has been inactive for `l` eras.
+		let proof = (0..l)
+			.map(|era| {
+				ErasRewardPoints::<T>::insert(
+					era,
+					EraRewardPoints {
+						total: 0,
+						individual: BTreeMap::from_iter([(stash.clone(), 0)]),
+					},
+				);
+
+				era
+			})
+			.collect::<Vec<_>>();
+		let proof = BoundedVec::truncate_from(proof);
+
+		#[extrinsic_call]
+		_(RawOrigin::Signed(caller), stash.clone(), proof);
+
+		assert!(!T::VoterList::contains(&stash));
+
+		Ok(())
+	}
+
 	impl_benchmark_test_suite!(
 		Staking,
 		crate::mock::ExtBuilder::default().has_stakers(true),

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

@@ -721,6 +721,15 @@ pub mod pallet {
 	#[pallet::storage]
 	pub(crate) type ChillThreshold<T: Config> = StorageValue<_, Percent, OptionQuery>;
 
+	/// The number of consecutive eras a validator can remain inactive before being subject to
+	/// chilling by anyone.
+	///
+	/// This must be equal or less than [`Config::HistoryDepth`] and greater than `2` for better
+	/// safety.
+	#[pallet::storage]
+	pub(crate) type ChillInactiveValidatorThreshold<T: Config> =
+		StorageValue<_, u32, ValueQuery, T::HistoryDepth>;
+
 	#[pallet::genesis_config]
 	#[derive(frame_support::DefaultNoBound)]
 	pub struct GenesisConfig<T: Config> {
@@ -867,6 +876,8 @@ pub mod pallet {
 		NotController,
 		/// Not a stash account.
 		NotStash,
+		/// Not a validator.
+		NotValidator,
 		/// Stash is already bonded.
 		AlreadyBonded,
 		/// Controller is already paired.
@@ -895,8 +906,13 @@ pub mod pallet {
 		NotSortedAndUnique,
 		/// Rewards for this era have already been claimed for this validator.
 		AlreadyClaimed,
+		// The threshold is greater than the [`Config::HistoryDepth`] or less than 2.
+		InvalidChillInactiveValidatorThreshold,
 		/// No nominators exist on this page.
 		InvalidPage,
+		/// Non-consecutive, unsorted, or insufficient era indexes were provided to chill an
+		/// inactive validator.
+		InvalidProof,
 		/// Incorrect previous history depth input provided.
 		IncorrectHistoryDepth,
 		/// Incorrect number of slashing spans provided.
@@ -1941,11 +1957,19 @@ pub mod pallet {
 			max_nominator_count: ConfigOp<u32>,
 			max_validator_count: ConfigOp<u32>,
 			chill_threshold: ConfigOp<Percent>,
+			chill_inactive_validator_threshold: ConfigOp<u32>,
 			min_commission: ConfigOp<Perbill>,
 			max_staked_rewards: ConfigOp<Percent>,
 		) -> DispatchResult {
 			ensure_root(origin)?;
 
+			if let ConfigOp::Set(threshold) = chill_inactive_validator_threshold {
+				ensure!(
+					threshold >= 2 && threshold <= T::HistoryDepth::get(),
+					Error::<T>::InvalidChillInactiveValidatorThreshold
+				);
+			}
+
 			macro_rules! config_op_exp {
 				($storage:ty, $op:ident) => {
 					match $op {
@@ -1961,10 +1985,13 @@ pub mod pallet {
 			config_op_exp!(MaxNominatorsCount<T>, max_nominator_count);
 			config_op_exp!(MaxValidatorsCount<T>, max_validator_count);
 			config_op_exp!(ChillThreshold<T>, chill_threshold);
+			config_op_exp!(ChillInactiveValidatorThreshold<T>, chill_inactive_validator_threshold);
 			config_op_exp!(MinCommission<T>, min_commission);
 			config_op_exp!(MaxStakedRewards<T>, max_staked_rewards);
+
 			Ok(())
 		}
+
 		/// Declare a `controller` to stop participating as either a validator or nominator.
 		///
 		/// Effects will be felt at the beginning of the next era.
@@ -2020,6 +2047,7 @@ pub mod pallet {
 			//
 			// Otherwise, if caller is the same as the controller, this is just like `chill`.
 
+			// Only if the key exists but the `OptionQuery`'s value is `None`.
 			if Nominators::<T>::contains_key(&stash) && Nominators::<T>::get(&stash).is_none() {
 				Self::chill_stash(&stash);
 				return Ok(())
@@ -2291,6 +2319,67 @@ pub mod pallet {
 			);
 			Ok(())
 		}
+
+		/// Chill an inactive validator.
+		///
+		/// - Anyone can call this function.
+		/// - The validator's stash account should be provided.
+		/// - The proof should be a list of consecutive sorted era indexes where the validator has
+		///   not produced any blocks.
+		/// - This will only be successful if the validator has not produced any blocks in
+		///   [`ChillInactiveValidatorThreshold`] consecutive eras.
+		#[pallet::call_index(30)]
+		#[pallet::weight(T::WeightInfo::chill_inactive_validator(proof.len() as _))]
+		pub fn chill_inactive_validator(
+			origin: OriginFor<T>,
+			stash: T::AccountId,
+			proof: BoundedVec<EraIndex, T::HistoryDepth>,
+		) -> DispatchResult {
+			ensure_signed(origin)?;
+
+			ensure!(Validators::<T>::contains_key(&stash), Error::<T>::NotValidator);
+
+			let threshold = ChillInactiveValidatorThreshold::<T>::get();
+
+			ensure!(proof.len() as EraIndex >= threshold, Error::<T>::InvalidProof);
+
+			// Check that the proof is sorted and consecutive.
+			for w in proof.windows(2) {
+				ensure!(w[1] == w[0] + 1, Error::<T>::InvalidProof);
+			}
+
+			let mut consecutive_inactives = 0;
+
+			for era in proof {
+				// Check if the ear exists.
+				if !ErasRewardPoints::<T>::contains_key(era) {
+					consecutive_inactives = 0;
+
+					continue;
+				}
+
+				// Check if the stash was a validator of the era.
+				let Some(&points) = ErasRewardPoints::<T>::get(era).individual.get(&stash) else {
+					consecutive_inactives = 0;
+
+					continue;
+				};
+
+				if points == 0 {
+					consecutive_inactives += 1;
+
+					if consecutive_inactives >= threshold {
+						Self::chill_stash(&stash);
+
+						return Ok(());
+					}
+				} else {
+					consecutive_inactives = 0;
+				}
+			}
+
+			Err(Error::<T>::InvalidProof)?
+		}
 	}
 }