[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 =
@@ -558,8 +558,6 @@ parameter_types! {
 	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 MaxExposurePageCount: u32 = 1;
-	pub const MaxNominatorRewardedPerValidator: u32 = MaxExposurePageSize::get() * MaxExposurePageCount::get();
 	pub const OffendingValidatorsThreshold: Perbill = Perbill::from_percent(17);
 	pub OffchainRepeat: BlockNumber = 5;
 	pub HistoryDepth: u32 = 84;
@@ -595,7 +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>;
@@ -1368,7 +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 =

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/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/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Changelog
 
-All notable changes to this project will be documented in this file.
+All notable changes and migrations to pallet-staking will be documented in this file.
 
 The format is loosely based
 on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/). We maintain a
@@ -19,9 +19,9 @@ migrations.
 
 ### Deprecated
 
-- `ErasStakersClipped` is deprecated and may be removed after 84 eras.
-- `ErasStakers` is deprecated and may be removed after 84 eras.
+- `ErasStakers` and `ErasStakersClipped` is deprecated, will not be used any longer for the exposures of the new era
+  post v14 and can be removed after 84 eras once all the exposures are stale.
 - Field `claimed_rewards` in item `Ledger` is renamed
-  to `legacy_claimed_rewards` and may be removed after 84 eras.
+  to `legacy_claimed_rewards` and can be removed after 84 eras.
 
 [v14]: https://github.com/paritytech/substrate/pull/13498

frame/staking/src/lib.rs

@@ -116,13 +116,11 @@
 //! [`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
 //! [`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
@@ -1169,28 +1167,14 @@ 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);
-
-			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_metadata, exposure_pages) = exposure.into_pages(page_size);
-		defensive_assert!(exposure_pages.len() == required_page_count, "unexpected page count");
+		defensive_assert!(exposure_pages.len() == expected_page_count, "unexpected page count");
 
 		<ErasStakersOverview<T>>::insert(era, &validator, &exposure_metadata);
 		exposure_pages.iter().enumerate().for_each(|(page, paged_exposure)| {

frame/staking/src/mock.rs

@@ -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 set_max_exposure_page_count(max_pages: PageIndex) {
-	MaxExposurePageCount::set(max_pages.max(1));
-}

frame/staking/src/pallet/mod.rs

@@ -214,15 +214,6 @@ pub mod pallet {
 		#[pallet::constant]
 		type MaxExposurePageSize: Get<u32>;
 
-		/// Maximum number of exposure pages that can be stored for a single validator in an era.
-		///
-		/// Must be greater than 0.
-		///
-		/// When this is set to 1, the reward payout behaviour is similar to how it used to work
-		/// before we had paged exposures.
-		#[pallet::constant]
-		type MaxExposurePageCount: Get<u32>;
-
 		/// The fraction of the validator set that is safe to be offending.
 		/// After the threshold is reached a new era will be forced.
 		type OffendingValidatorsThreshold: Get<Perbill>;

frame/staking/src/tests.rs

@@ -3692,9 +3692,9 @@ fn six_session_delay() {
 }
 
 #[test]
-fn test_max_nominator_rewarded_per_validator_and_cant_steal_someone_else_reward() {
-	// with max exposure page count set to 1, clipped exposure logic works exactly as before.
+fn test_nominators_over_max_exposure_page_size_are_rewarded() {
 	ExtBuilder::default().build_and_execute(|| {
+		// bond one nominator more than the max exposure page size to validator 11.
 		for i in 0..=MaxExposurePageSize::get() {
 			let stash = 10_000 + i as AccountId;
 			let balance = 10_000 + i as Balance;
@@ -3715,25 +3715,24 @@ fn test_max_nominator_rewarded_per_validator_and_cant_steal_someone_else_reward(
 		mock::start_active_era(2);
 		mock::make_all_reward_payment(1);
 
-		// Assert only nominators from 1 to Max are rewarded
-		for i in 0..=MaxExposurePageSize::get() {
+		// Assert nominators from 1 to Max are rewarded
+		let mut i: u32 = 0;
+		while i < MaxExposurePageSize::get() {
 			let stash = 10_000 + i as AccountId;
 			let balance = 10_000 + i as Balance;
-			if stash == 10_000 {
-				assert!(Balances::free_balance(&stash) == balance);
-			} else {
-				assert!(Balances::free_balance(&stash) > balance);
-			}
+			assert!(Balances::free_balance(&stash) > balance);
+			i += 1;
 		}
+
+		// Assert overflowing nominators from page 1 are also rewarded
+		let stash = 10_000 + i as AccountId;
+		assert!(Balances::free_balance(&stash) > (10_000 + i) as Balance);
 	});
 }
 
 #[test]
 fn test_nominators_are_rewarded_for_all_exposure_page() {
 	ExtBuilder::default().build_and_execute(|| {
-		// enable multi paged rewards payout
-		set_max_exposure_page_count(3);
-
 		// 3 pages of exposure
 		let nominator_count = 2 * MaxExposurePageSize::get() + 1;
 
@@ -3780,9 +3779,6 @@ fn test_nominators_are_rewarded_for_all_exposure_page() {
 fn test_multi_page_payout_stakers_by_page() {
 	// Test that payout_stakers work in general and that it pays the correct amount of reward.
 	ExtBuilder::default().has_stakers(false).build_and_execute(|| {
-		// enable multi paged rewards payout
-		set_max_exposure_page_count(10);
-
 		let balance = 1000;
 		// Track the exposure of the validator and all nominators.
 		let mut total_exposure = balance;
@@ -3977,9 +3973,6 @@ fn test_multi_page_payout_stakers_by_page() {
 fn test_multi_page_payout_stakers_backward_compatible() {
 	// Test that payout_stakers work in general and that it pays the correct amount of reward.
 	ExtBuilder::default().has_stakers(false).build_and_execute(|| {
-		// enable multi paged rewards payout
-		set_max_exposure_page_count(10);
-
 		let balance = 1000;
 		// Track the exposure of the validator and all nominators.
 		let mut total_exposure = balance;
@@ -4226,69 +4219,38 @@ fn test_page_count_and_size() {
 
 		mock::start_active_era(1);
 
-		// Since max exposure page count is 1, we should only have 1 page with clipped and sorted
-		// nominators.
-		assert_eq!(EraInfo::<Test>::get_page_count(1, &11), 1);
-		let exposure = EraInfo::<Test>::get_paged_exposure(1, &11, 0).unwrap();
-		let mut previous_nominator_balance: Balance = u32::MAX as Balance;
-		exposure.others().iter().for_each(|e| {
-			// Nominators are sorted by balance in descending order.
-			assert!(e.value < previous_nominator_balance);
-			previous_nominator_balance = e.value;
-		});
-
-		// the last nominator balance is higher than the last 36 clipped nominators.
-		assert_eq!(previous_nominator_balance, 1000 + 36);
-
-		// increase max page size
-		set_max_exposure_page_count(10);
-		mock::start_active_era(2);
+		// Since max exposure page size is 64, 2 pages of nominators are created.
+		assert_eq!(EraInfo::<Test>::get_page_count(1, &11), 2);
 
-		assert_eq!(EraInfo::<Test>::get_page_count(2, &11), 2);
 		// first page has 64 nominators
-		assert_eq!(EraInfo::<Test>::get_paged_exposure(2, &11, 0).unwrap().others().len(), 64);
+		assert_eq!(EraInfo::<Test>::get_paged_exposure(1, &11, 0).unwrap().others().len(), 64);
 		// second page has 36 nominators
-		assert_eq!(EraInfo::<Test>::get_paged_exposure(2, &11, 1).unwrap().others().len(), 36);
+		assert_eq!(EraInfo::<Test>::get_paged_exposure(1, &11, 1).unwrap().others().len(), 36);
 
 		// now lets decrease page size
 		MaxExposurePageSize::set(32);
-		mock::start_active_era(3);
+		mock::start_active_era(2);
 		// now we expect 4 pages.
-		assert_eq!(EraInfo::<Test>::get_page_count(3, &11), 4);
+		assert_eq!(EraInfo::<Test>::get_page_count(2, &11), 4);
 		// first 3 pages have 32 nominators each
-		assert_eq!(EraInfo::<Test>::get_paged_exposure(3, &11, 0).unwrap().others().len(), 32);
-		assert_eq!(EraInfo::<Test>::get_paged_exposure(3, &11, 1).unwrap().others().len(), 32);
-		assert_eq!(EraInfo::<Test>::get_paged_exposure(3, &11, 2).unwrap().others().len(), 32);
-		assert_eq!(EraInfo::<Test>::get_paged_exposure(3, &11, 3).unwrap().others().len(), 4);
+		assert_eq!(EraInfo::<Test>::get_paged_exposure(2, &11, 0).unwrap().others().len(), 32);
+		assert_eq!(EraInfo::<Test>::get_paged_exposure(2, &11, 1).unwrap().others().len(), 32);
+		assert_eq!(EraInfo::<Test>::get_paged_exposure(2, &11, 2).unwrap().others().len(), 32);
+		assert_eq!(EraInfo::<Test>::get_paged_exposure(2, &11, 3).unwrap().others().len(), 4);
 
 		// now lets decrease page size even more
-		MaxExposurePageSize::set(9);
-		mock::start_active_era(4);
-		// now we expect the max 10 pages with each page having 9 nominators.
-		assert_eq!(EraInfo::<Test>::get_page_count(4, &11), 10);
-
-		// all nominators are sorted by balance in descending order.
-		let mut previous_nominator_balance: Balance = u32::MAX as Balance;
-		for page in 0..10 {
-			let exposure = EraInfo::<Test>::get_paged_exposure(4, &11, page).unwrap();
-			exposure.others().iter().for_each(|e| {
-				assert!(e.value < previous_nominator_balance);
-				previous_nominator_balance = e.value;
-			});
-		}
+		MaxExposurePageSize::set(5);
+		mock::start_active_era(3);
 
-		// the last nominator balance is higher than the last 10 clipped nominators.
-		assert_eq!(previous_nominator_balance, 1000 + 10);
+		// now we expect the max 20 pages (100/5).
+		assert_eq!(EraInfo::<Test>::get_page_count(3, &11), 20);
 	});
 }
 
 #[test]
 fn payout_stakers_handles_basic_errors() {
 	// Here we will test payouts handle all errors.
 	ExtBuilder::default().has_stakers(false).build_and_execute(|| {
-		// enable multi paged rewards payout
-		set_max_exposure_page_count(2);
-
 		// Consumed weight for all payout_stakers dispatches that fail
 		let err_weight = <Test as Config>::WeightInfo::payout_stakers_alive_staked(0);
 
@@ -4421,9 +4383,6 @@ fn payout_stakers_handles_basic_errors() {
 #[test]
 fn test_commission_paid_across_pages() {
 	ExtBuilder::default().has_stakers(false).build_and_execute(|| {
-		// enable multi paged rewards payout
-		set_max_exposure_page_count(4);
-
 		let balance = 1;
 		let commission = 50;
 		// Create a validator:
@@ -6617,9 +6576,6 @@ fn test_legacy_claimed_rewards_is_checked_at_reward_payout() {
 #[test]
 fn test_validator_exposure_is_backward_compatible_with_non_paged_rewards_payout() {
 	ExtBuilder::default().has_stakers(false).build_and_execute(|| {
-		// enable multi paged rewards payout
-		set_max_exposure_page_count(2);
-
 		// case 1: exposure exist in clipped.
 		// set page cap to 10
 		MaxExposurePageSize::set(10);