Store validator self-vote in bags-list, and allow them to be trimmed for election (paritytech#10821)

* Implement the new validator-in-bags-list scenario + migration

* Apply suggestions from code review

Co-authored-by: Zeke Mostov <z.mostov@gmail.com>

* some review comments

* guard the migration

* some review comments

* Fix tests 🤦‍♂️

* Fix build

* fix weight_of_fn

* reformat line width

* make const

* use weight of fn cached

* SortedListProvider -> VoterList

* Fix all build and docs

* check post migration

Co-authored-by: Zeke Mostov <z.mostov@gmail.com>

Author: kianenigma

bin/node/runtime/src/lib.rs

@@ -558,9 +558,7 @@ impl pallet_staking::Config for Runtime {
 	type OffendingValidatorsThreshold = OffendingValidatorsThreshold;
 	type ElectionProvider = ElectionProviderMultiPhase;
 	type GenesisElectionProvider = onchain::OnChainSequentialPhragmen<Self>;
-	// Alternatively, use pallet_staking::UseNominatorsMap<Runtime> to just use the nominators map.
-	// Note that the aforementioned does not scale to a very large number of nominators.
-	type SortedListProvider = BagsList;
+	type VoterList = BagsList;
 	type MaxUnlockingChunks = ConstU32<32>;
 	type WeightInfo = pallet_staking::weights::SubstrateWeight<Runtime>;
 	type BenchmarkingConfig = StakingBenchmarkingConfig;

frame/babe/src/mock.rs

@@ -197,7 +197,7 @@ impl pallet_staking::Config for Test {
 	type NextNewSession = Session;
 	type ElectionProvider = onchain::OnChainSequentialPhragmen<Self>;
 	type GenesisElectionProvider = Self::ElectionProvider;
-	type SortedListProvider = pallet_staking::UseNominatorsMap<Self>;
+	type VoterList = pallet_staking::UseNominatorsAndValidatorsMap<Self>;
 	type MaxUnlockingChunks = ConstU32<32>;
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;
 	type WeightInfo = ();

frame/bags-list/remote-tests/src/lib.rs

@@ -48,7 +48,7 @@ pub fn display_and_check_bags<Runtime: RuntimeT>(currency_unit: u64, currency_na
 	let min_nominator_bond = <pallet_staking::MinNominatorBond<Runtime>>::get();
 	log::info!(target: LOG_TARGET, "min nominator bond is {:?}", min_nominator_bond);
 
-	let voter_list_count = <Runtime as pallet_staking::Config>::SortedListProvider::count();
+	let voter_list_count = <Runtime as pallet_staking::Config>::VoterList::count();
 
 	// go through every bag to track the total number of voters within bags and log some info about
 	// how voters are distributed within the bags.

frame/bags-list/remote-tests/src/migration.rs

@@ -17,7 +17,6 @@
 //! Test to check the migration of the voter bag.
 
 use crate::{RuntimeT, LOG_TARGET};
-use frame_election_provider_support::SortedListProvider;
 use frame_support::traits::PalletInfoAccess;
 use pallet_staking::Nominators;
 use remote_externalities::{Builder, Mode, OnlineConfig};
@@ -45,16 +44,16 @@ pub async fn execute<Runtime: RuntimeT, Block: BlockT + DeserializeOwned>(
 		let pre_migrate_nominator_count = <Nominators<Runtime>>::iter().count() as u32;
 		log::info!(target: LOG_TARGET, "Nominator count: {}", pre_migrate_nominator_count);
 
-		// run the actual migration,
-		let moved = <Runtime as pallet_staking::Config>::SortedListProvider::unsafe_regenerate(
+		use frame_election_provider_support::SortedListProvider;
+		// run the actual migration
+		let moved = <Runtime as pallet_staking::Config>::VoterList::unsafe_regenerate(
 			pallet_staking::Nominators::<Runtime>::iter().map(|(n, _)| n),
 			pallet_staking::Pallet::<Runtime>::weight_of_fn(),
 		);
 		log::info!(target: LOG_TARGET, "Moved {} nominators", moved);
 
-		let voter_list_len =
-			<Runtime as pallet_staking::Config>::SortedListProvider::iter().count() as u32;
-		let voter_list_count = <Runtime as pallet_staking::Config>::SortedListProvider::count();
+		let voter_list_len = <Runtime as pallet_staking::Config>::VoterList::iter().count() as u32;
+		let voter_list_count = <Runtime as pallet_staking::Config>::VoterList::count();
 		// and confirm it is equal to the length of the `VoterList`.
 		assert_eq!(pre_migrate_nominator_count, voter_list_len);
 		assert_eq!(pre_migrate_nominator_count, voter_list_count);

frame/bags-list/remote-tests/src/snapshot.rs

@@ -16,6 +16,7 @@
 
 //! Test to execute the snapshot using the voter bag.
 
+use frame_election_provider_support::SortedListProvider;
 use frame_support::traits::PalletInfoAccess;
 use remote_externalities::{Builder, Mode, OnlineConfig};
 use sp_runtime::{traits::Block as BlockT, DeserializeOwned};
@@ -48,11 +49,11 @@ pub async fn execute<Runtime: crate::RuntimeT, Block: BlockT + DeserializeOwned>
 		.unwrap();
 
 	ext.execute_with(|| {
-		use frame_election_provider_support::{ElectionDataProvider, SortedListProvider};
+		use frame_election_provider_support::ElectionDataProvider;
 		log::info!(
 			target: crate::LOG_TARGET,
 			"{} nodes in bags list.",
-			<Runtime as pallet_staking::Config>::SortedListProvider::count(),
+			<Runtime as pallet_staking::Config>::VoterList::count(),
 		);
 
 		let voters =

frame/grandpa/src/mock.rs

@@ -205,7 +205,7 @@ impl pallet_staking::Config for Test {
 	type NextNewSession = Session;
 	type ElectionProvider = onchain::OnChainSequentialPhragmen<Self>;
 	type GenesisElectionProvider = Self::ElectionProvider;
-	type SortedListProvider = pallet_staking::UseNominatorsMap<Self>;
+	type VoterList = pallet_staking::UseNominatorsAndValidatorsMap<Self>;
 	type MaxUnlockingChunks = ConstU32<32>;
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;
 	type WeightInfo = ();

frame/offences/benchmarking/src/mock.rs

@@ -175,7 +175,7 @@ impl pallet_staking::Config for Test {
 	type OffendingValidatorsThreshold = ();
 	type ElectionProvider = onchain::OnChainSequentialPhragmen<Self>;
 	type GenesisElectionProvider = Self::ElectionProvider;
-	type SortedListProvider = pallet_staking::UseNominatorsMap<Self>;
+	type VoterList = pallet_staking::UseNominatorsAndValidatorsMap<Self>;
 	type MaxUnlockingChunks = ConstU32<32>;
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;
 	type WeightInfo = ();

frame/session/benchmarking/src/mock.rs

@@ -182,7 +182,7 @@ impl pallet_staking::Config for Test {
 	type ElectionProvider = onchain::OnChainSequentialPhragmen<Self>;
 	type GenesisElectionProvider = Self::ElectionProvider;
 	type MaxUnlockingChunks = ConstU32<32>;
-	type SortedListProvider = pallet_staking::UseNominatorsMap<Self>;
+	type VoterList = pallet_staking::UseNominatorsAndValidatorsMap<Self>;
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;
 	type WeightInfo = ();
 }

frame/session/src/migrations/v1.rs

@@ -87,7 +87,7 @@ pub fn migrate<T: pallet_session_historical::Config, P: GetStorageVersion + Pall
 }
 
 /// Some checks prior to migration. This can be linked to
-/// [`frame_support::traits::OnRuntimeUpgrade::pre_upgrade`] for further testing.
+/// `frame_support::traits::OnRuntimeUpgrade::pre_upgrade` for further testing.
 ///
 /// Panics if anything goes wrong.
 pub fn pre_migrate<
@@ -123,7 +123,7 @@ pub fn pre_migrate<
 }
 
 /// Some checks for after migration. This can be linked to
-/// [`frame_support::traits::OnRuntimeUpgrade::post_upgrade`] for further testing.
+/// `frame_support::traits::OnRuntimeUpgrade::post_upgrade` for further testing.
 ///
 /// Panics if anything goes wrong.
 pub fn post_migrate<

frame/staking/src/benchmarking.rs

@@ -155,8 +155,8 @@ impl<T: Config> ListScenario<T> {
 	/// - the destination bag has at least one node, which will need its next pointer updated.
 	///
 	/// NOTE: while this scenario specifically targets a worst case for the bags-list, it should
-	/// also elicit a worst case for other known `SortedListProvider` implementations; although
-	/// this may not be true against unknown `SortedListProvider` implementations.
+	/// also elicit a worst case for other known `VoterList` implementations; although
+	/// this may not be true against unknown `VoterList` implementations.
 	fn new(origin_weight: BalanceOf<T>, is_increase: bool) -> Result<Self, &'static str> {
 		ensure!(!origin_weight.is_zero(), "origin weight must be greater than 0");
 
@@ -189,7 +189,7 @@ impl<T: Config> ListScenario<T> {
 
 		// find a destination weight that will trigger the worst case scenario
 		let dest_weight_as_vote =
-			T::SortedListProvider::score_update_worst_case(&origin_stash1, is_increase);
+			T::VoterList::score_update_worst_case(&origin_stash1, is_increase);
 
 		let total_issuance = T::Currency::total_issuance();
 
@@ -316,7 +316,7 @@ benchmarks! {
 		let scenario = ListScenario::<T>::new(origin_weight, true)?;
 		let controller = scenario.origin_controller1.clone();
 		let stash = scenario.origin_stash1.clone();
-		assert!(T::SortedListProvider::contains(&stash));
+		assert!(T::VoterList::contains(&stash));
 
 		let ed = T::Currency::minimum_balance();
 		let mut ledger = Ledger::<T>::get(&controller).unwrap();
@@ -328,28 +328,24 @@ benchmarks! {
 	}: withdraw_unbonded(RawOrigin::Signed(controller.clone()), s)
 	verify {
 		assert!(!Ledger::<T>::contains_key(controller));
-		assert!(!T::SortedListProvider::contains(&stash));
+		assert!(!T::VoterList::contains(&stash));
 	}
 
 	validate {
-		// clean up any existing state.
-		clear_validators_and_nominators::<T>();
-
-		let origin_weight = MinNominatorBond::<T>::get().max(T::Currency::minimum_balance());
-
-		// setup a worst case scenario where the user calling validate was formerly a nominator so
-		// they must be removed from the list.
-		let scenario = ListScenario::<T>::new(origin_weight, true)?;
-		let controller = scenario.origin_controller1.clone();
-		let stash = scenario.origin_stash1.clone();
-		assert!(T::SortedListProvider::contains(&stash));
+		let (stash, controller) = create_stash_controller::<T>(
+			T::MaxNominations::get() - 1,
+			100,
+			Default::default(),
+		)?;
+		// because it is chilled.
+		assert!(!T::VoterList::contains(&stash));
 
 		let prefs = ValidatorPrefs::default();
 		whitelist_account!(controller);
 	}: _(RawOrigin::Signed(controller), prefs)
 	verify {
 		assert!(Validators::<T>::contains_key(&stash));
-		assert!(!T::SortedListProvider::contains(&stash));
+		assert!(T::VoterList::contains(&stash));
 	}
 
 	kick {
@@ -434,14 +430,14 @@ benchmarks! {
 		).unwrap();
 
 		assert!(!Nominators::<T>::contains_key(&stash));
-		assert!(!T::SortedListProvider::contains(&stash));
+		assert!(!T::VoterList::contains(&stash));
 
 		let validators = create_validators::<T>(n, 100).unwrap();
 		whitelist_account!(controller);
 	}: _(RawOrigin::Signed(controller), validators)
 	verify {
 		assert!(Nominators::<T>::contains_key(&stash));
-		assert!(T::SortedListProvider::contains(&stash))
+		assert!(T::VoterList::contains(&stash))
 	}
 
 	chill {
@@ -455,12 +451,12 @@ benchmarks! {
 		let scenario = ListScenario::<T>::new(origin_weight, true)?;
 		let controller = scenario.origin_controller1.clone();
 		let stash = scenario.origin_stash1.clone();
-		assert!(T::SortedListProvider::contains(&stash));
+		assert!(T::VoterList::contains(&stash));
 
 		whitelist_account!(controller);
 	}: _(RawOrigin::Signed(controller))
 	verify {
-		assert!(!T::SortedListProvider::contains(&stash));
+		assert!(!T::VoterList::contains(&stash));
 	}
 
 	set_payee {
@@ -523,13 +519,13 @@ benchmarks! {
 		let scenario = ListScenario::<T>::new(origin_weight, true)?;
 		let controller = scenario.origin_controller1.clone();
 		let stash = scenario.origin_stash1.clone();
-		assert!(T::SortedListProvider::contains(&stash));
+		assert!(T::VoterList::contains(&stash));
 		add_slashing_spans::<T>(&stash, s);
 
 	}: _(RawOrigin::Root, stash.clone(), s)
 	verify {
 		assert!(!Ledger::<T>::contains_key(&controller));
-		assert!(!T::SortedListProvider::contains(&stash));
+		assert!(!T::VoterList::contains(&stash));
 	}
 
 	cancel_deferred_slash {
@@ -708,13 +704,13 @@ benchmarks! {
 		Ledger::<T>::insert(&controller, l);
 
 		assert!(Bonded::<T>::contains_key(&stash));
-		assert!(T::SortedListProvider::contains(&stash));
+		assert!(T::VoterList::contains(&stash));
 
 		whitelist_account!(controller);
 	}: _(RawOrigin::Signed(controller), stash.clone(), s)
 	verify {
 		assert!(!Bonded::<T>::contains_key(&stash));
-		assert!(!T::SortedListProvider::contains(&stash));
+		assert!(!T::VoterList::contains(&stash));
 	}
 
 	new_era {
@@ -899,7 +895,7 @@ benchmarks! {
 		let scenario = ListScenario::<T>::new(origin_weight, true)?;
 		let controller = scenario.origin_controller1.clone();
 		let stash = scenario.origin_stash1.clone();
-		assert!(T::SortedListProvider::contains(&stash));
+		assert!(T::VoterList::contains(&stash));
 
 		Staking::<T>::set_staking_configs(
 			RawOrigin::Root.into(),
@@ -914,7 +910,7 @@ benchmarks! {
 		let caller = whitelisted_caller();
 	}: _(RawOrigin::Signed(caller), controller.clone())
 	verify {
-		assert!(!T::SortedListProvider::contains(&stash));
+		assert!(!T::VoterList::contains(&stash));
 	}
 
 	force_apply_min_commission {