disputes rewards (#5862)

* refactor backing points to only reward active set

* impl disputes::RewardValidators

* enable rewards on westend, kusama, polkadot

* fmt

* make dispute points same as backing

* disable on polkadot for now

polkadot/runtime/kusama/src/lib.rs

@@ -1169,7 +1169,7 @@ impl parachains_initializer::Config for Runtime {
 
 impl parachains_disputes::Config for Runtime {
 	type Event = Event;
-	type RewardValidators = ();
+	type RewardValidators = parachains_reward_points::RewardValidatorsWithEraPoints<Runtime>;
 	type PunishValidators = ();
 	type WeightInfo = weights::runtime_parachains_disputes::WeightInfo<Runtime>;
 }

polkadot/runtime/parachains/src/reward_points.rs

@@ -22,42 +22,71 @@
 //! for the time being, although we will build schemes to do so in the future.
 
 use crate::{session_info, shared};
-use frame_support::traits::ValidatorSet;
-use primitives::v2::ValidatorIndex;
+use frame_support::traits::{Defensive, ValidatorSet};
+use primitives::v2::{SessionIndex, ValidatorIndex};
+use sp_std::collections::btree_set::BTreeSet;
 
 /// The amount of era points given by backing a candidate that is included.
 pub const BACKING_POINTS: u32 = 20;
+/// The amount of era points given by dispute voting on a candidate.
+pub const DISPUTE_STATEMENT_POINTS: u32 = 20;
 
 /// Rewards validators for participating in parachains with era points in pallet-staking.
 pub struct RewardValidatorsWithEraPoints<C>(sp_std::marker::PhantomData<C>);
 
+impl<C> RewardValidatorsWithEraPoints<C>
+where
+	C: pallet_staking::Config + session_info::Config,
+	C::ValidatorSet: ValidatorSet<C::AccountId, ValidatorId = C::AccountId>,
+{
+	/// Reward validators in session with points, but only if they are in the active set.
+	fn reward_only_active(
+		session_index: SessionIndex,
+		indices: impl IntoIterator<Item = ValidatorIndex>,
+		points: u32,
+	) {
+		let validators = session_info::Pallet::<C>::account_keys(&session_index);
+		let validators = match validators
+			.defensive_proof("account_keys are present for dispute_period sessions")
+		{
+			Some(validators) => validators,
+			None => return,
+		};
+		// limit rewards to the active validator set
+		let active_set: BTreeSet<_> = C::ValidatorSet::validators().into_iter().collect();
+
+		let rewards = indices
+			.into_iter()
+			.filter_map(|i| validators.get(i.0 as usize).cloned())
+			.filter(|v| active_set.contains(v))
+			.map(|v| (v, points));
+
+		<pallet_staking::Pallet<C>>::reward_by_ids(rewards);
+	}
+}
+
 impl<C> crate::inclusion::RewardValidators for RewardValidatorsWithEraPoints<C>
 where
 	C: pallet_staking::Config + shared::Config + session_info::Config,
 	C::ValidatorSet: ValidatorSet<C::AccountId, ValidatorId = C::AccountId>,
 {
 	fn reward_backing(indices: impl IntoIterator<Item = ValidatorIndex>) {
-		// Fetch the validators from the _session_ because sessions are offset from eras
-		// and we are rewarding for behavior in current session.
 		let session_index = shared::Pallet::<C>::session_index();
-		let validators = session_info::Pallet::<C>::account_keys(&session_index);
-		let validators = match validators {
-			Some(validators) => validators,
-			None => {
-				// Account keys are missing for the current session.
-				// This might happen only for the first session after
-				// `AccountKeys` were introduced via runtime upgrade.
-				return
-			},
-		};
-
-		let rewards = indices
-			.into_iter()
-			.filter_map(|i| validators.get(i.0 as usize).cloned())
-			.map(|v| (v, BACKING_POINTS));
-
-		<pallet_staking::Pallet<C>>::reward_by_ids(rewards);
+		Self::reward_only_active(session_index, indices, BACKING_POINTS);
 	}
 
 	fn reward_bitfields(_validators: impl IntoIterator<Item = ValidatorIndex>) {}
 }
+
+impl<C> crate::disputes::RewardValidators for RewardValidatorsWithEraPoints<C>
+where
+	C: pallet_staking::Config + session_info::Config,
+	C::ValidatorSet: ValidatorSet<C::AccountId, ValidatorId = C::AccountId>,
+{
+	fn reward_dispute_statement(
+		session: SessionIndex,
+		validators: impl IntoIterator<Item = ValidatorIndex>,
+	) {
+		Self::reward_only_active(session, validators, DISPUTE_STATEMENT_POINTS);
+	}
+}

polkadot/runtime/westend/src/lib.rs

@@ -944,7 +944,7 @@ impl assigned_slots::Config for Runtime {
 
 impl parachains_disputes::Config for Runtime {
 	type Event = Event;
-	type RewardValidators = ();
+	type RewardValidators = parachains_reward_points::RewardValidatorsWithEraPoints<Runtime>;
 	type PunishValidators = ();
 	type WeightInfo = weights::runtime_parachains_disputes::WeightInfo<Runtime>;
 }