Adds multi-block election types and refactors current pallets to support new interfaces and types

polkadot/runtime/westend/src/lib.rs

@@ -582,7 +582,10 @@ parameter_types! {
 		ElectionBoundsBuilder::default().voters_count(MaxElectingVoters::get().into()).build();
 	// Maximum winners that can be chosen as active validators
 	pub const MaxActiveValidators: u32 = 1000;
-
+	// One page only, fill the whole page with the `MaxActiveValidators`.
+	pub const MaxWinnersPerPage: u32 = MaxActiveValidators::get();
+	// Unbonded, thus the max backers per winner maps to the max electing voters limit.
+	pub const MaxBackersPerWinner: u32 = MaxElectingVoters::get();
 }
 
 frame_election_provider_support::generate_solution_type!(
@@ -601,8 +604,9 @@ impl onchain::Config for OnChainSeqPhragmen {
 	type Solver = SequentialPhragmen<AccountId, OnChainAccuracy>;
 	type DataProvider = Staking;
 	type WeightInfo = weights::frame_election_provider_support::WeightInfo<Runtime>;
-	type MaxWinners = MaxActiveValidators;
 	type Bounds = ElectionBounds;
+	type MaxBackersPerWinner = MaxBackersPerWinner;
+	type MaxWinnersPerPage = MaxWinnersPerPage;
 }
 
 impl pallet_election_provider_multi_phase::MinerConfig for Runtime {
@@ -615,7 +619,8 @@ impl pallet_election_provider_multi_phase::MinerConfig for Runtime {
     as
     frame_election_provider_support::ElectionDataProvider
     >::MaxVotesPerVoter;
-	type MaxWinners = MaxActiveValidators;
+	type MaxWinnersPerPage = MaxWinnersPerPage;
+	type MaxBackersPerWinner = MaxBackersPerWinner;
 
 	// The unsigned submissions have to respect the weight of the submit_unsigned call, thus their
 	// weight estimate function is wired to this call's weight.
@@ -649,6 +654,9 @@ impl pallet_election_provider_multi_phase::Config for Runtime {
 	type BetterSignedThreshold = ();
 	type OffchainRepeat = OffchainRepeat;
 	type MinerTxPriority = NposSolutionPriority;
+	type Pages = ConstU32<1>;
+	type MaxWinnersPerPage = MaxWinnersPerPage;
+	type MaxBackersPerWinner = MaxBackersPerWinner;
 	type DataProvider = Staking;
 	#[cfg(any(feature = "fast-runtime", feature = "runtime-benchmarks"))]
 	type Fallback = onchain::OnChainExecution<OnChainSeqPhragmen>;
@@ -657,7 +665,8 @@ impl pallet_election_provider_multi_phase::Config for Runtime {
 		AccountId,
 		BlockNumber,
 		Staking,
-		MaxActiveValidators,
+		MaxWinnersPerPage,
+		MaxBackersPerWinner,
 	)>;
 	type GovernanceFallback = onchain::OnChainExecution<OnChainSeqPhragmen>;
 	type Solver = SequentialPhragmen<
@@ -668,7 +677,6 @@ impl pallet_election_provider_multi_phase::Config for Runtime {
 	type BenchmarkingConfig = polkadot_runtime_common::elections::BenchmarkConfig;
 	type ForceOrigin = EnsureRoot<AccountId>;
 	type WeightInfo = weights::pallet_election_provider_multi_phase::WeightInfo<Self>;
-	type MaxWinners = MaxActiveValidators;
 	type ElectionBounds = ElectionBounds;
 }
 
@@ -748,6 +756,7 @@ impl pallet_staking::Config for Runtime {
 	type GenesisElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;
 	type VoterList = VoterList;
 	type TargetList = UseValidatorsMap<Self>;
+	type MaxValidatorSet = MaxActiveValidators;
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<{ MaxNominations::get() }>;
 	type MaxUnlockingChunks = frame_support::traits::ConstU32<32>;
 	type HistoryDepth = frame_support::traits::ConstU32<84>;

prdoc/pr_6034.prdoc

@@ -0,0 +1,25 @@
+title: Adds multi-block election types and refactors current single logic to support it
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      This PR adds election types and structs required to run a multi-block election. In addition,
+      it modifies EPM, staking pallet and all dependent pallets and logic to use the multi-block types.
+
+crates:
+ - name: frame-election-provider-support
+   bump: major
+ - name: pallet-election-provider-multi-phase
+   bump: major
+ - name: pallet-staking
+   bump: major
+ - name: pallet-fast-unstake
+   bump: minor
+ - name: pallet-delegated-staking
+   bump: minor
+ - name: sp-npos-elections
+   bump: major
+ - name: sp-staking
+   bump: major
+ - name: pallet-bags-list-remote-tests
+   bump: minor

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

@@ -22,7 +22,10 @@ use frame_election_provider_support::{
 };
 use frame_support::traits::PalletInfoAccess;
 use remote_externalities::{Builder, Mode, OnlineConfig};
-use sp_runtime::{traits::Block as BlockT, DeserializeOwned};
+use sp_runtime::{
+	traits::{Block as BlockT, Zero},
+	DeserializeOwned,
+};
 
 /// Execute create a snapshot from pallet-staking.
 pub async fn execute<Runtime, Block>(voter_limit: Option<usize>, currency_unit: u64, ws_url: String)
@@ -70,8 +73,9 @@ where
 			Some(v) => DataProviderBounds { count: Some(CountBound(v as u32)), size: None },
 		};
 
+		// single page voter snapshot, thus page index == 0.
 		let voters =
-			<pallet_staking::Pallet<Runtime> as ElectionDataProvider>::electing_voters(bounds)
+			<pallet_staking::Pallet<Runtime> as ElectionDataProvider>::electing_voters(bounds, Zero::zero())
 				.unwrap();
 
 		let mut voters_nominator_only = voters

substrate/frame/delegated-staking/src/mock.rs

@@ -96,7 +96,8 @@ impl onchain::Config for OnChainSeqPhragmen {
 	type Solver = SequentialPhragmen<Balance, sp_runtime::Perbill>;
 	type DataProvider = Staking;
 	type WeightInfo = ();
-	type MaxWinners = ConstU32<100>;
+	type MaxWinnersPerPage = ConstU32<100>;
+	type MaxBackersPerWinner = ConstU32<100>;
 	type Bounds = ElectionsBoundsOnChain;
 }
 

substrate/frame/election-provider-multi-phase/src/benchmarking.rs

@@ -288,9 +288,11 @@ mod benchmarks {
 	) -> Result<(), BenchmarkError> {
 		// We don't directly need the data-provider to be populated, but it is just easy to use it.
 		set_up_data_provider::<T>(v, t);
-		// Default bounds are unbounded.
-		let targets = T::DataProvider::electable_targets(DataProviderBounds::default())?;
-		let voters = T::DataProvider::electing_voters(DataProviderBounds::default())?;
+		// default bounds are unbounded.
+		let targets =
+			T::DataProvider::electable_targets(DataProviderBounds::default(), Zero::zero())?;
+		let voters = T::DataProvider::electing_voters(DataProviderBounds::default(), Zero::zero())?;
+
 		let desired_targets = T::DataProvider::desired_targets()?;
 		assert!(Snapshot::<T>::get().is_none());
 
@@ -343,7 +345,7 @@ mod benchmarks {
 
 		#[block]
 		{
-			result = <Pallet<T> as ElectionProvider>::elect();
+			result = <Pallet<T> as ElectionProvider>::elect(Zero::zero());
 		}
 
 		assert!(result.is_ok());