[NPoS] Unlimited number of nominators eligible for Rewards payout

bin/node/runtime/src/lib.rs

@@ -416,7 +416,7 @@ impl pallet_babe::Config for Runtime {
 	type DisabledValidators = Session;
 	type WeightInfo = ();
 	type MaxAuthorities = MaxAuthorities;
-	type MaxNominators = MaxNominatorRewardedPerValidator;
+	type MaxNominators = MaxExposurePageSize;
 	type KeyOwnerProof =
 		<Historical as KeyOwnerProofSystem<(KeyTypeId, pallet_babe::AuthorityId)>>::Proof;
 	type EquivocationReportSystem =
@@ -557,6 +557,7 @@ parameter_types! {
 	pub const BondingDuration: sp_staking::EraIndex = 24 * 28;
 	pub const SlashDeferDuration: sp_staking::EraIndex = 24 * 7; // 1/4 the bonding duration.
 	pub const RewardCurve: &'static PiecewiseLinear<'static> = &REWARD_CURVE;
+	pub const MaxExposurePageSize: u32 = 256;
 	pub const OffendingValidatorsThreshold: Perbill = Perbill::from_percent(17);
 	pub OffchainRepeat: BlockNumber = 5;
 	pub HistoryDepth: u32 = 84;
@@ -592,7 +593,6 @@ impl pallet_staking::Config for Runtime {
 	type EraPayout = pallet_staking::ConvertCurve<RewardCurve>;
 	type NextNewSession = Session;
 	type MaxExposurePageSize = ConstU32<256>;
-	type MaxExposurePageCount = ConstU32<1>;
 	type OffendingValidatorsThreshold = OffendingValidatorsThreshold;
 	type ElectionProvider = ElectionProviderMultiPhase;
 	type GenesisElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;
@@ -1365,7 +1365,7 @@ impl pallet_grandpa::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type WeightInfo = ();
 	type MaxAuthorities = MaxAuthorities;
-	type MaxNominators = MaxNominatorRewardedPerValidator;
+	type MaxNominators = MaxExposurePageSize;
 	type MaxSetIdSessionEntries = MaxSetIdSessionEntries;
 	type KeyOwnerProof = <Historical as KeyOwnerProofSystem<(KeyTypeId, GrandpaId)>>::Proof;
 	type EquivocationReportSystem =
@@ -2206,8 +2206,8 @@ impl_runtime_apis! {
 			Staking::api_nominations_quota(balance)
 		}
 
-		fn era_page_count(era: sp_staking::EraIndex, account: AccountId) -> sp_staking::PageIndex {
-			Staking::api_era_page_count(era, account)
+		fn eras_stakers_page_count(era: sp_staking::EraIndex, account: AccountId) -> sp_staking::PageIndex {
+			Staking::api_eras_stakers_page_count(era, account)
 		}
 	}
 

frame/babe/src/mock.rs

@@ -194,7 +194,6 @@ impl pallet_staking::Config for Test {
 	type UnixTime = pallet_timestamp::Pallet<Test>;
 	type EraPayout = pallet_staking::ConvertCurve<RewardCurve>;
 	type MaxExposurePageSize = ConstU32<64>;
-	type MaxExposurePageCount = ConstU32<1>;
 	type OffendingValidatorsThreshold = OffendingValidatorsThreshold;
 	type NextNewSession = Session;
 	type ElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;

frame/beefy/src/mock.rs

@@ -216,7 +216,6 @@ impl pallet_staking::Config for Test {
 	type UnixTime = pallet_timestamp::Pallet<Test>;
 	type EraPayout = pallet_staking::ConvertCurve<RewardCurve>;
 	type MaxExposurePageSize = ConstU32<64>;
-	type MaxExposurePageCount = ConstU32<1>;
 	type OffendingValidatorsThreshold = OffendingValidatorsThreshold;
 	type NextNewSession = Session;
 	type ElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;

frame/election-provider-multi-phase/test-staking-e2e/src/mock.rs

@@ -270,7 +270,6 @@ impl pallet_staking::Config for Runtime {
 	type EraPayout = ();
 	type NextNewSession = Session;
 	type MaxExposurePageSize = ConstU32<256>;
-	type MaxExposurePageCount = ConstU32<1>;
 	type OffendingValidatorsThreshold = OffendingValidatorsThreshold;
 	type ElectionProvider = ElectionProviderMultiPhase;
 	type GenesisElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;

frame/fast-unstake/src/benchmarking.rs

@@ -76,7 +76,7 @@ fn setup_staking<T: Config>(v: u32, until: EraIndex) {
 	for era in 0..=until {
 		let others = (0..T::Staking::max_exposure_page_size())
 			.map(|s| {
-				let who = frame_benchmarking::account::<T::AccountId>("nominator", era, s);
+				let who = frame_benchmarking::account::<T::AccountId>("nominator", era, s.into());
 				let value = ed;
 				(who, value)
 			})

frame/fast-unstake/src/mock.rs

@@ -152,7 +152,6 @@ impl pallet_staking::Config for Runtime {
 	type NextNewSession = ();
 	type HistoryDepth = ConstU32<84>;
 	type MaxExposurePageSize = ConstU32<64>;
-	type MaxExposurePageCount = ConstU32<1>;
 	type OffendingValidatorsThreshold = ();
 	type ElectionProvider = MockElection;
 	type GenesisElectionProvider = Self::ElectionProvider;

frame/grandpa/src/mock.rs

@@ -196,7 +196,6 @@ impl pallet_staking::Config for Test {
 	type UnixTime = pallet_timestamp::Pallet<Test>;
 	type EraPayout = pallet_staking::ConvertCurve<RewardCurve>;
 	type MaxExposurePageSize = ConstU32<64>;
-	type MaxExposurePageCount = ConstU32<1>;
 	type OffendingValidatorsThreshold = OffendingValidatorsThreshold;
 	type NextNewSession = Session;
 	type ElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;

frame/nomination-pools/benchmarking/src/mock.rs

@@ -109,7 +109,6 @@ impl pallet_staking::Config for Runtime {
 	type SessionInterface = ();
 	type EraPayout = pallet_staking::ConvertCurve<RewardCurve>;
 	type NextNewSession = ();
-	type MaxExposurePageCount = ConstU32<1>;
 	type MaxExposurePageSize = ConstU32<64>;
 	type OffendingValidatorsThreshold = ();
 	type ElectionProvider =

frame/nomination-pools/test-staking/src/mock.rs

@@ -123,7 +123,6 @@ impl pallet_staking::Config for Runtime {
 	type SessionInterface = ();
 	type EraPayout = pallet_staking::ConvertCurve<RewardCurve>;
 	type NextNewSession = ();
-	type MaxExposurePageCount = ConstU32<1>;
 	type MaxExposurePageSize = ConstU32<64>;
 	type OffendingValidatorsThreshold = ();
 	type ElectionProvider =

frame/offences/benchmarking/src/mock.rs

@@ -175,7 +175,6 @@ impl pallet_staking::Config for Test {
 	type SessionInterface = Self;
 	type EraPayout = pallet_staking::ConvertCurve<RewardCurve>;
 	type NextNewSession = Session;
-	type MaxExposurePageCount = ConstU32<1>;
 	type MaxExposurePageSize = ConstU32<64>;
 	type OffendingValidatorsThreshold = ();
 	type ElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;

frame/root-offences/src/mock.rs

@@ -178,7 +178,6 @@ impl pallet_staking::Config for Test {
 	type SessionInterface = Self;
 	type EraPayout = pallet_staking::ConvertCurve<RewardCurve>;
 	type NextNewSession = Session;
-	type MaxExposurePageCount = ConstU32<1>;
 	type MaxExposurePageSize = ConstU32<64>;
 	type OffendingValidatorsThreshold = OffendingValidatorsThreshold;
 	type ElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;

frame/session/benchmarking/src/mock.rs

@@ -172,7 +172,6 @@ impl pallet_staking::Config for Test {
 	type SessionInterface = Self;
 	type EraPayout = pallet_staking::ConvertCurve<RewardCurve>;
 	type NextNewSession = Session;
-	type MaxExposurePageCount = ConstU32<1>;
 	type MaxExposurePageSize = ConstU32<64>;
 	type OffendingValidatorsThreshold = ();
 	type ElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;

frame/staking/README.md

@@ -52,7 +52,7 @@ An account pair can become bonded using the [`bond`](https://docs.rs/pallet-stak
 
 Stash accounts can update their associated controller back to their stash account using the
 [`set_controller`](https://docs.rs/pallet-staking/latest/pallet_staking/enum.Call.html#variant.set_controller)
-call. 
+call.
 
 Note: Controller accounts are being deprecated in favor of proxy accounts, so it is no longer
 possible to set a unique address for a stash's controller.
@@ -92,11 +92,13 @@ An account can become a nominator via the [`nominate`](https://docs.rs/pallet-st
 The **reward and slashing** procedure is the core of the Staking module, attempting to _embrace
 valid behavior_ while _punishing any misbehavior or lack of availability_.
 
-Rewards must be claimed for each era before it gets too old by [`HistoryDepth`] using the
-`payout_stakers` call. Any account can call `payout_stakers`, which pays the reward to the
-validator as well as its nominators. Rewards are paged to maximum of [`Config::MaxExposurePageSize`]
-nominators per page. Each page of staker payout needs to be called separately to ensure all nominators are
-paid. This is to limit the i/o cost to mutate storage for each nominator's account.
+Rewards must be claimed on a per-era basis via the `payout_stakers` call, and must be claimed before
+[`HistoryDepth`] eras have passed since the reward's inclusion, after which any unclaimed rewards
+will expire and be removed from storage. Any account can call `payout_stakers`, which pays the reward
+to the validator as well as its nominators. Rewards are paged to maximum of
+[`Config::MaxExposurePageSize`] nominators per page. Each page of staker payout needs to be called
+separately to ensure all nominators are paid. This is to limit the i/o cost to mutate storage for
+each nominator's account.
 
 Slashing can occur at any point in time, once misbehavior is reported. Once slashing is
 determined, a value is deducted from the balance of the validator and all the nominators who

frame/staking/runtime-api/Cargo.toml

@@ -13,7 +13,7 @@ readme = "README.md"
 targets = ["x86_64-unknown-linux-gnu"]
 
 [dependencies]
-codec = { package = "parity-scale-codec", version = "3.2.2", default-features = false, features = ["derive"] }
+codec = { package = "parity-scale-codec", version = "3.6.1", default-features = false, features = ["derive"] }
 sp-api = { version = "4.0.0-dev", default-features = false, path = "../../../primitives/api" }
 sp-staking = { version = "4.0.0-dev", default-features = false, path = "../../../primitives/staking" }
 

frame/staking/runtime-api/src/lib.rs

@@ -30,7 +30,7 @@ sp_api::decl_runtime_apis! {
 		/// Returns the nominations quota for a nominator with a given balance.
 		fn nominations_quota(balance: Balance) -> u32;
 
-		/// Returns the count of pages exposure of the validator is split into.
-		fn era_page_count(era: sp_staking::EraIndex, account: AccountId) -> sp_staking::PageIndex;
+		/// Returns the page count of exposures for a validator in a given era.
+		fn eras_stakers_page_count(era: sp_staking::EraIndex, account: AccountId) -> sp_staking::PageIndex;
 	}
 }

frame/staking/src/lib.rs

@@ -114,15 +114,13 @@
 //!
 //! Rewards must be claimed for each era before it gets too old by
 //! [`HistoryDepth`](`Config::HistoryDepth`) using the `payout_stakers` call. Any account can call
-//! `payout_stakers`, which pays the reward to the validator as well as its nominators. Only the
+//! `payout_stakers`, which pays the reward to the validator as well as its nominators. Only
 //! [`Config::MaxExposurePageSize`] nominator rewards can be claimed in a single call. When the
-//! number of nominators exceeds [`Config::MaxExposurePageSize`], then the nominators are stored in
-//! multiple pages of [`Config::MaxExposurePageSize`], each with up to a maximum of
-//! [`Config::MaxExposurePageCount`] pages. To pay out all nominators, `payout_stakers` must be
-//! called once for each available page. In a scenario where the number of nominators N exceed M,
-//! where M = [`Config::MaxExposurePageSize`] * [`Config::MaxExposurePageCount`], only the top M
-//! nominators by stake balance are paid out. The rest of the nominators are not paid out. Paging
-//! exists to limit the i/o cost to mutate storage for each nominator's account.
+//! number of nominators exceeds [`Config::MaxExposurePageSize`], then the exposed nominators are
+//! stored in multiple pages, with each page containing up to
+//! [`Config::MaxExposurePageSize`] nominators. To pay out all nominators, `payout_stakers` must be
+//! called once for each available page. Paging exists to limit the i/o cost to mutate storage for
+//! each nominator's account.
 //!
 //! Slashing can occur at any point in time, once misbehavior is reported. Once slashing is
 //! determined, a value is deducted from the balance of the validator and all the nominators who
@@ -309,7 +307,7 @@ mod pallet;
 use codec::{Decode, Encode, HasCompact, MaxEncodedLen};
 use frame_support::{
 	defensive, defensive_assert,
-	traits::{Currency, Defensive, DefensiveMax, DefensiveSaturating, Get},
+	traits::{ConstU32, Currency, Defensive, DefensiveMax, DefensiveSaturating, Get},
 	weights::Weight,
 	BoundedVec, CloneNoBound, EqNoBound, PartialEqNoBound, RuntimeDebugNoBound,
 };
@@ -321,7 +319,7 @@ use sp_runtime::{
 };
 use sp_staking::{
 	offence::{Offence, OffenceError, ReportOffence},
-	EraIndex, ExposureOverview, ExposurePage, PageIndex, SessionIndex,
+	EraIndex, ExposurePage, OnStakingUpdate, PageIndex, PagedExposureMetadata, SessionIndex,
 };
 pub use sp_staking::{Exposure, IndividualExposure, StakerStatus};
 use sp_std::{collections::btree_map::BTreeMap, prelude::*};
@@ -706,23 +704,23 @@ pub struct Nominations<T: Config> {
 	pub suppressed: bool,
 }
 
-/// Extended view of Exposure comprising of `ExposureOverview` and a single page of `ExposurePage`.
+/// Facade struct to encapsulate `PagedExposureMetadata` and a single page of `ExposurePage`.
 ///
 /// This is useful where we need to take into account the validator's own stake and total exposure
 /// in consideration, in addition to the individual nominators backing them.
 #[derive(Encode, Decode, RuntimeDebug, TypeInfo, PartialEq, Eq)]
-struct ExposureExt<AccountId, Balance: HasCompact + codec::MaxEncodedLen> {
-	exposure_overview: ExposureOverview<Balance>,
+struct PagedExposure<AccountId, Balance: HasCompact + codec::MaxEncodedLen> {
+	exposure_metadata: PagedExposureMetadata<Balance>,
 	exposure_page: ExposurePage<AccountId, Balance>,
 }
 
 impl<AccountId, Balance: HasCompact + Copy + AtLeast32BitUnsigned + codec::MaxEncodedLen>
-	ExposureExt<AccountId, Balance>
+	PagedExposure<AccountId, Balance>
 {
-	/// Create a new instance of `ExposureExt` from legacy clipped exposures.
+	/// Create a new instance of `PagedExposure` from legacy clipped exposures.
 	pub fn from_clipped(exposure: Exposure<AccountId, Balance>) -> Self {
 		Self {
-			exposure_overview: ExposureOverview {
+			exposure_metadata: PagedExposureMetadata {
 				total: exposure.total,
 				own: exposure.own,
 				nominator_count: exposure.others.len() as u32,
@@ -734,17 +732,17 @@ impl<AccountId, Balance: HasCompact + Copy + AtLeast32BitUnsigned + codec::MaxEn
 
 	/// Returns total exposure of this validator across pages
 	pub fn total(&self) -> Balance {
-		self.exposure_overview.total
+		self.exposure_metadata.total
 	}
 
 	/// Returns total exposure of this validator for the current page
 	pub fn page_total(&self) -> Balance {
-		self.exposure_page.page_total + self.exposure_overview.own
+		self.exposure_page.page_total + self.exposure_metadata.own
 	}
 
 	/// Returns validator's own stake that is exposed
 	pub fn own(&self) -> Balance {
-		self.exposure_overview.own
+		self.exposure_metadata.own
 	}
 
 	/// Returns the portions of nominators stashes that are exposed in this page.
@@ -1032,19 +1030,19 @@ impl<T: Config> EraInfo<T> {
 
 	/// Get exposure for a validator at a given era and page.
 	///
-	/// This builds a paged exposure from `ExposureOverview` and `ExposurePage` of the validator.
-	/// For older non-paged exposure, it returns the clipped exposure directly.
+	/// This builds a paged exposure from `PagedExposureMetadata` and `ExposurePage` of the
+	/// validator. For older non-paged exposure, it returns the clipped exposure directly.
 	pub(crate) fn get_paged_exposure(
 		era: EraIndex,
 		validator: &T::AccountId,
 		page: PageIndex,
-	) -> Option<ExposureExt<T::AccountId, BalanceOf<T>>> {
+	) -> Option<PagedExposure<T::AccountId, BalanceOf<T>>> {
 		let overview = <ErasStakersOverview<T>>::get(&era, validator);
 
 		// return clipped exposure if page zero and paged exposure does not exist
 		// exists for backward compatibility and can be removed as part of #13034
 		if overview.is_none() && page == 0 {
-			return Some(ExposureExt::from_clipped(<ErasStakersClipped<T>>::get(era, validator)))
+			return Some(PagedExposure::from_clipped(<ErasStakersClipped<T>>::get(era, validator)))
 		}
 
 		// no exposure for this validator
@@ -1062,8 +1060,8 @@ impl<T: Config> EraInfo<T> {
 		let exposure_page = <ErasStakersPaged<T>>::get((era, validator, page)).unwrap_or_default();
 
 		// build the exposure
-		Some(ExposureExt {
-			exposure_overview: ExposureOverview { own: validator_stake, ..overview },
+		Some(PagedExposure {
+			exposure_metadata: PagedExposureMetadata { own: validator_stake, ..overview },
 			exposure_page,
 		})
 	}
@@ -1169,32 +1167,18 @@ impl<T: Config> EraInfo<T> {
 		exposure: Exposure<T::AccountId, BalanceOf<T>>,
 	) {
 		let page_size = T::MaxExposurePageSize::get().defensive_max(1);
-		let max_page_count = T::MaxExposurePageCount::get();
 
 		let nominator_count = exposure.others.len();
-		let mut required_page_count =
+		// expected page count is the number of nominators divided by the page size, rounded up.
+		let expected_page_count =
 			nominator_count.defensive_saturating_add(page_size as usize - 1) / page_size as usize;
 
-		// clip nominators if it exceeds the maximum page count.
-		let exposure = if required_page_count as PageIndex > max_page_count {
-			required_page_count = max_page_count as usize;
-			// sort before clipping.
-			let mut exposure_clipped = exposure;
-			let clipped_max_len = max_page_count.saturating_mul(page_size);
+		let (exposure_metadata, exposure_pages) = exposure.into_pages(page_size);
+		defensive_assert!(exposure_pages.len() == expected_page_count, "unexpected page count");
 
-			exposure_clipped.others.sort_by(|a, b| b.value.cmp(&a.value));
-			exposure_clipped.others.truncate(clipped_max_len as usize);
-			exposure_clipped
-		} else {
-			exposure
-		};
-
-		let (exposure_overview, exposure_pages) = exposure.into_pages(page_size);
-		defensive_assert!(exposure_pages.len() == required_page_count, "unexpected page count");
-
-		<ErasStakersOverview<T>>::insert(era, &validator, &exposure_overview);
+		<ErasStakersOverview<T>>::insert(era, &validator, &exposure_metadata);
 		exposure_pages.iter().enumerate().for_each(|(page, paged_exposure)| {
-			<ErasStakersPaged<T>>::insert((era, &validator, page as u32), &paged_exposure);
+			<ErasStakersPaged<T>>::insert((era, &validator, page as PageIndex), &paged_exposure);
 		});
 	}
 

frame/staking/src/mock.rs

@@ -25,8 +25,8 @@ use frame_election_provider_support::{
 use frame_support::{
 	assert_ok, ord_parameter_types, parameter_types,
 	traits::{
-		ConstU32, ConstU64, Currency, EitherOfDiverse, FindAuthor, Get, Hooks, Imbalance,
-		OnUnbalanced, OneSessionHandler,
+		ConstU64, Currency, EitherOfDiverse, FindAuthor, Get, Hooks, Imbalance, OnUnbalanced,
+		OneSessionHandler,
 	},
 	weights::constants::RocksDbWeight,
 };
@@ -233,7 +233,6 @@ parameter_types! {
 	pub static BagThresholds: &'static [sp_npos_elections::VoteWeight] = &THRESHOLDS;
 	pub static HistoryDepth: u32 = 80;
 	pub static MaxExposurePageSize: u32 = 64;
-	pub static MaxExposurePageCount: u32 = 1;
 	pub static MaxUnlockingChunks: u32 = 32;
 	pub static RewardOnUnbalanceWasCalled: bool = false;
 	pub static MaxWinners: u32 = 100;
@@ -302,7 +301,6 @@ impl crate::pallet::pallet::Config for Test {
 	type EraPayout = ConvertCurve<RewardCurve>;
 	type NextNewSession = Session;
 	type MaxExposurePageSize = MaxExposurePageSize;
-	type MaxExposurePageCount = MaxExposurePageCount;
 	type OffendingValidatorsThreshold = OffendingValidatorsThreshold;
 	type ElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;
 	type GenesisElectionProvider = Self::ElectionProvider;
@@ -837,7 +835,3 @@ pub(crate) fn staking_events_since_last_call() -> Vec<crate::Event<Test>> {
 pub(crate) fn balances(who: &AccountId) -> (Balance, Balance) {
 	(Balances::free_balance(who), Balances::reserved_balance(who))
 }
-
-pub(crate) fn allow_paged_rewards(max_pages: u32) {
-	MaxExposurePageCount::set(max_pages.max(1));
-}