Decouple Staking and Election - Part 2 Unsigned Phase (paritytech#7909)

* Base features and traits.

* pallet and unsigned phase

* Undo bad formattings.

* some formatting cleanup.

* Small self-cleanup.

* Make it all build

* self-review

* Some doc tests.

* Some changes from other PR

* Fix session test

* Update Cargo.lock

* Update frame/election-provider-multi-phase/src/lib.rs

Co-authored-by: Guillaume Thiolliere <[email protected]>

* Some review comments

* Rename + make encode/decode

* Do an assert as well, just in case.

* Fix build

* Update frame/election-provider-multi-phase/src/unsigned.rs

Co-authored-by: Guillaume Thiolliere <[email protected]>

* Las comment

* fix staking fuzzer.

* cargo run --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_election_provider_multi_phase --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/election-provider-multi-phase/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* Add one last layer of feasibility check as well.

* Last fixes to benchmarks

* Some more docs.

* cargo run --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_election_provider_multi_phase --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/election-provider-multi-phase/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* cargo run --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_election_provider_multi_phase --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/election-provider-multi-phase/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* Some nits

* cargo run --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_staking --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/staking/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* Fix doc

* Mkae ci green

Co-authored-by: Shawn Tabrizi <[email protected]>
Co-authored-by: Guillaume Thiolliere <[email protected]>
Co-authored-by: Parity Benchmarking Bot <[email protected]>

Cargo.toml

@@ -75,6 +75,7 @@ members = [
 	"frame/democracy",
 	"frame/try-runtime",
 	"frame/elections",
+	"frame/election-provider-multi-phase",
 	"frame/example",
 	"frame/example-offchain-worker",
 	"frame/example-parallel",

bin/node/runtime/Cargo.toml

@@ -56,6 +56,7 @@ pallet-contracts-primitives = { version = "2.0.0", default-features = false, pat
 pallet-contracts-rpc-runtime-api = { version = "0.8.0", default-features = false, path = "../../../frame/contracts/rpc/runtime-api/" }
 pallet-democracy = { version = "3.0.0", default-features = false, path = "../../../frame/democracy" }
 pallet-elections-phragmen = { version = "3.0.0", default-features = false, path = "../../../frame/elections-phragmen" }
+pallet-election-provider-multi-phase = { version = "3.0.0", default-features = false, path = "../../../frame/election-provider-multi-phase" }
 pallet-grandpa = { version = "3.0.0", default-features = false, path = "../../../frame/grandpa" }
 pallet-im-online = { version = "3.0.0", default-features = false, path = "../../../frame/im-online" }
 pallet-indices = { version = "3.0.0", default-features = false, path = "../../../frame/indices" }
@@ -141,6 +142,7 @@ std = [
 	"frame-benchmarking/std",
 	"frame-system-rpc-runtime-api/std",
 	"frame-system/std",
+	"pallet-election-provider-multi-phase/std",
 	"pallet-timestamp/std",
 	"pallet-tips/std",
 	"pallet-transaction-payment-rpc-runtime-api/std",
@@ -157,6 +159,7 @@ runtime-benchmarks = [
 	"frame-benchmarking",
 	"frame-support/runtime-benchmarks",
 	"frame-system/runtime-benchmarks",
+	"pallet-election-provider-multi-phase/runtime-benchmarks",
 	"sp-runtime/runtime-benchmarks",
 	"pallet-assets/runtime-benchmarks",
 	"pallet-babe/runtime-benchmarks",

bin/node/runtime/src/constants.rs

@@ -35,7 +35,7 @@ pub mod time {
 	use node_primitives::{Moment, BlockNumber};
 
 	/// Since BABE is probabilistic this is the average expected block time that
-	/// we are targetting. Blocks will be produced at a minimum duration defined
+	/// we are targeting. Blocks will be produced at a minimum duration defined
 	/// by `SLOT_DURATION`, but some slots will not be allocated to any
 	/// authority and hence no block will be produced. We expect to have this
 	/// block time on average following the defined slot duration and the value

bin/node/runtime/src/lib.rs

@@ -28,7 +28,8 @@ use frame_support::{
 	construct_runtime, parameter_types, debug, RuntimeDebug,
 	weights::{
 		Weight, IdentityFee,
-		constants::{BlockExecutionWeight, ExtrinsicBaseWeight, RocksDbWeight, WEIGHT_PER_SECOND}, DispatchClass,
+		constants::{BlockExecutionWeight, ExtrinsicBaseWeight, RocksDbWeight, WEIGHT_PER_SECOND},
+		DispatchClass,
 	},
 	traits::{
 		Currency, Imbalance, KeyOwnerProofSystem, OnUnbalanced, Randomness, LockIdentifier,
@@ -50,14 +51,14 @@ pub use node_primitives::{AccountId, Signature};
 use node_primitives::{AccountIndex, Balance, BlockNumber, Hash, Index, Moment};
 use sp_api::impl_runtime_apis;
 use sp_runtime::{
-	Permill, Perbill, Perquintill, Percent, ApplyExtrinsicResult,
-	impl_opaque_keys, generic, create_runtime_str, ModuleId, FixedPointNumber,
+	Permill, Perbill, Perquintill, Percent, ApplyExtrinsicResult, impl_opaque_keys, generic,
+	create_runtime_str, ModuleId, FixedPointNumber,
 };
 use sp_runtime::curve::PiecewiseLinear;
 use sp_runtime::transaction_validity::{TransactionValidity, TransactionSource, TransactionPriority};
 use sp_runtime::traits::{
-	self, BlakeTwo256, Block as BlockT, StaticLookup, SaturatedConversion,
-	ConvertInto, OpaqueKeys, NumberFor,
+	self, BlakeTwo256, Block as BlockT, StaticLookup, SaturatedConversion, ConvertInto, OpaqueKeys,
+	NumberFor,
 };
 use sp_version::RuntimeVersion;
 #[cfg(any(feature = "std", test))]
@@ -145,7 +146,7 @@ impl OnUnbalanced<NegativeImbalance> for DealWithFees {
 	}
 }
 
-/// We assume that ~10% of the block weight is consumed by `on_initalize` handlers.
+/// We assume that ~10% of the block weight is consumed by `on_initialize` handlers.
 /// This is used to limit the maximal weight of a single extrinsic.
 const AVERAGE_ON_INITIALIZE_RATIO: Perbill = Perbill::from_percent(10);
 /// We allow `Normal` extrinsics to fill up the block up to 75%, the rest can be used
@@ -490,18 +491,56 @@ impl pallet_staking::Config for Runtime {
 	type SessionInterface = Self;
 	type RewardCurve = RewardCurve;
 	type NextNewSession = Session;
+	type MaxNominatorRewardedPerValidator = MaxNominatorRewardedPerValidator;
 	type ElectionLookahead = ElectionLookahead;
 	type Call = Call;
 	type MaxIterations = MaxIterations;
 	type MinSolutionScoreBump = MinSolutionScoreBump;
-	type MaxNominatorRewardedPerValidator = MaxNominatorRewardedPerValidator;
 	type UnsignedPriority = StakingUnsignedPriority;
 	// The unsigned solution weight targeted by the OCW. We set it to the maximum possible value of
 	// a single extrinsic.
 	type OffchainSolutionWeightLimit = OffchainSolutionWeightLimit;
+	type ElectionProvider = ElectionProviderMultiPhase;
 	type WeightInfo = pallet_staking::weights::SubstrateWeight<Runtime>;
 }
 
+parameter_types! {
+	// phase durations. 1/4 of the last session for each.
+	pub const SignedPhase: u32 = EPOCH_DURATION_IN_BLOCKS / 4;
+	pub const UnsignedPhase: u32 = EPOCH_DURATION_IN_BLOCKS / 4;
+
+	// fallback: no need to do on-chain phragmen initially.
+	pub const Fallback: pallet_election_provider_multi_phase::FallbackStrategy =
+		pallet_election_provider_multi_phase::FallbackStrategy::Nothing;
+
+	pub SolutionImprovementThreshold: Perbill = Perbill::from_rational_approximation(1u32, 10_000);
+
+	// miner configs
+	pub const MultiPhaseUnsignedPriority: TransactionPriority = StakingUnsignedPriority::get() - 1u64;
+	pub const MinerMaxIterations: u32 = 10;
+	pub MinerMaxWeight: Weight = RuntimeBlockWeights::get()
+		.get(DispatchClass::Normal)
+		.max_extrinsic.expect("Normal extrinsics have a weight limit configured; qed")
+		.saturating_sub(BlockExecutionWeight::get());
+}
+
+impl pallet_election_provider_multi_phase::Config for Runtime {
+	type Event = Event;
+	type Currency = Balances;
+	type SignedPhase = SignedPhase;
+	type UnsignedPhase = UnsignedPhase;
+	type SolutionImprovementThreshold = MinSolutionScoreBump;
+	type MinerMaxIterations = MinerMaxIterations;
+	type MinerMaxWeight = MinerMaxWeight;
+	type MinerTxPriority = MultiPhaseUnsignedPriority;
+	type DataProvider = Staking;
+	type OnChainAccuracy = Perbill;
+	type CompactSolution = pallet_staking::CompactAssignments;
+	type Fallback = Fallback;
+	type WeightInfo = pallet_election_provider_multi_phase::weights::SubstrateWeight<Runtime>;
+	type BenchmarkingConfig = ();
+}
+
 parameter_types! {
 	pub const LaunchPeriod: BlockNumber = 28 * 24 * 60 * MINUTES;
 	pub const VotingPeriod: BlockNumber = 28 * 24 * 60 * MINUTES;
@@ -548,7 +587,7 @@ impl pallet_democracy::Config for Runtime {
 	>;
 	type BlacklistOrigin = EnsureRoot<AccountId>;
 	// Any single technical committee member may veto a coming council proposal, however they can
-	// only do it once and it lasts only for the cooloff period.
+	// only do it once and it lasts only for the cool-off period.
 	type VetoOrigin = pallet_collective::EnsureMember<AccountId, TechnicalCollective>;
 	type CooloffPeriod = CooloffPeriod;
 	type PreimageByteDeposit = PreimageByteDeposit;
@@ -1020,6 +1059,7 @@ construct_runtime!(
 		Indices: pallet_indices::{Module, Call, Storage, Config<T>, Event<T>},
 		Balances: pallet_balances::{Module, Call, Storage, Config<T>, Event<T>},
 		TransactionPayment: pallet_transaction_payment::{Module, Storage},
+		ElectionProviderMultiPhase: pallet_election_provider_multi_phase::{Module, Call, Storage, Event<T>, ValidateUnsigned},
 		Staking: pallet_staking::{Module, Call, Config<T>, Storage, Event<T>, ValidateUnsigned},
 		Session: pallet_session::{Module, Call, Storage, Event, Config<T>},
 		Democracy: pallet_democracy::{Module, Call, Storage, Config, Event<T>},
@@ -1386,6 +1426,7 @@ impl_runtime_apis! {
 			add_benchmark!(params, batches, pallet_contracts, Contracts);
 			add_benchmark!(params, batches, pallet_democracy, Democracy);
 			add_benchmark!(params, batches, pallet_elections_phragmen, Elections);
+			add_benchmark!(params, batches, pallet_election_provider_multi_phase, ElectionProviderMultiPhase);
 			add_benchmark!(params, batches, pallet_grandpa, Grandpa);
 			add_benchmark!(params, batches, pallet_identity, Identity);
 			add_benchmark!(params, batches, pallet_im_online, ImOnline);

frame/babe/Cargo.toml

@@ -32,12 +32,12 @@ sp-std = { version = "3.0.0", default-features = false, path = "../../primitives
 sp-timestamp = { version = "3.0.0", default-features = false, path = "../../primitives/timestamp" }
 
 [dev-dependencies]
-frame-benchmarking = { version = "3.0.0", path = "../benchmarking" }
 pallet-balances = { version = "3.0.0", path = "../balances" }
 pallet-offences = { version = "3.0.0", path = "../offences" }
 pallet-staking = { version = "3.0.0", path = "../staking" }
 pallet-staking-reward-curve = { version = "3.0.0", path = "../staking/reward-curve" }
 sp-core = { version = "3.0.0", path = "../../primitives/core" }
+sp-election-providers = { version = "3.0.0", path = "../../primitives/election-providers" }
 
 [features]
 default = ["std"]

frame/babe/src/lib.rs

@@ -413,12 +413,14 @@ impl<T: Config> Module<T> {
 	/// In other word, this is only accurate if no slots are missed. Given missed slots, the slot
 	/// number will grow while the block number will not. Hence, the result can be interpreted as an
 	/// upper bound.
-	// -------------- IMPORTANT NOTE --------------
+	//
+	// ## IMPORTANT NOTE
+	//
 	// This implementation is linked to how [`should_epoch_change`] is working. This might need to
 	// be updated accordingly, if the underlying mechanics of slot and epochs change.
 	//
-	// WEIGHT NOTE: This function is tied to the weight of `EstimateNextSessionRotation`. If you update
-	// this function, you must also update the corresponding weight.
+	// WEIGHT NOTE: This function is tied to the weight of `EstimateNextSessionRotation`. If you
+	// update this function, you must also update the corresponding weight.
 	pub fn next_expected_epoch_change(now: T::BlockNumber) -> Option<T::BlockNumber> {
 		let next_slot = Self::current_epoch_start().saturating_add(T::EpochDuration::get());
 		next_slot
@@ -754,6 +756,10 @@ impl<T: Config> OnTimestampSet<T::Moment> for Module<T> {
 }
 
 impl<T: Config> frame_support::traits::EstimateNextSessionRotation<T::BlockNumber> for Module<T> {
+	fn average_session_length() -> T::BlockNumber {
+		T::EpochDuration::get().saturated_into()
+	}
+
 	fn estimate_next_session_rotation(now: T::BlockNumber) -> Option<T::BlockNumber> {
 		Self::next_expected_epoch_change(now)
 	}

frame/babe/src/mock.rs

@@ -37,6 +37,7 @@ use sp_consensus_babe::{AuthorityId, AuthorityPair, Slot};
 use sp_consensus_vrf::schnorrkel::{VRFOutput, VRFProof};
 use sp_staking::SessionIndex;
 use pallet_staking::EraIndex;
+use sp_election_providers::onchain;
 use pallet_session::historical as pallet_session_historical;
 
 type DummyValidatorId = u64;
@@ -183,6 +184,13 @@ parameter_types! {
 	pub const StakingUnsignedPriority: u64 = u64::max_value() / 2;
 }
 
+impl onchain::Config for Test {
+	type AccountId = <Self as frame_system::Config>::AccountId;
+	type BlockNumber = <Self as frame_system::Config>::BlockNumber;
+	type Accuracy = Perbill;
+	type DataProvider = Staking;
+}
+
 impl pallet_staking::Config for Test {
 	type RewardRemainder = ();
 	type CurrencyToVote = frame_support::traits::SaturatingCurrencyToVote;
@@ -205,6 +213,7 @@ impl pallet_staking::Config for Test {
 	type MaxIterations = ();
 	type MinSolutionScoreBump = ();
 	type OffchainSolutionWeightLimit = ();
+	type ElectionProvider = onchain::OnChainSequentialPhragmen<Self>;
 	type WeightInfo = ();
 }
 

frame/election-provider-multi-phase/Cargo.toml

@@ -0,0 +1,66 @@
+[package]
+name = "pallet-election-provider-multi-phase"
+version = "3.0.0"
+authors = ["Parity Technologies <[email protected]>"]
+edition = "2018"
+license = "Apache-2.0"
+homepage = "https://substrate.dev"
+repository = "https://github.com/paritytech/substrate/"
+description = "PALLET two phase election providers"
+readme = "README.md"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[dependencies]
+static_assertions = "1.1.0"
+serde = { version = "1.0.101", optional = true }
+codec = { package = "parity-scale-codec", version = "2.0.0", default-features = false, features = ["derive"] }
+
+frame-support = { version = "3.0.0", default-features = false, path = "../support" }
+frame-system = { version = "3.0.0", default-features = false, path = "../system" }
+
+sp-io ={ version = "3.0.0", default-features = false, path = "../../primitives/io" }
+sp-std = { version = "3.0.0", default-features = false, path = "../../primitives/std" }
+sp-runtime = { version = "3.0.0", default-features = false, path = "../../primitives/runtime" }
+sp-npos-elections = { version = "3.0.0", default-features = false, path = "../../primitives/npos-elections" }
+sp-arithmetic = { version = "3.0.0", default-features = false, path = "../../primitives/arithmetic" }
+sp-election-providers = { version = "3.0.0", default-features = false, path = "../../primitives/election-providers" }
+
+# Optional imports for benchmarking
+frame-benchmarking = { version = "3.0.0", default-features = false, path = "../benchmarking", optional = true }
+rand = { version = "0.7.3", default-features = false, optional = true, features = ["alloc", "small_rng"] }
+
+[dev-dependencies]
+paste = "1.0.3"
+parking_lot = "0.11.0"
+rand = { version = "0.7.3" }
+hex-literal = "0.3.1"
+substrate-test-utils = { version = "3.0.0", path = "../../test-utils" }
+sp-io = { version = "3.0.0", path = "../../primitives/io" }
+sp-core = { version = "3.0.0", path = "../../primitives/core" }
+sp-tracing = { version = "3.0.0", path = "../../primitives/tracing" }
+sp-election-providers = { version = "3.0.0", features = ["runtime-benchmarks"], path = "../../primitives/election-providers" }
+pallet-balances = { version = "3.0.0", path = "../balances" }
+frame-benchmarking = { path = "../benchmarking" }
+
+[features]
+default = ["std"]
+std = [
+	"serde",
+	"codec/std",
+
+	"frame-support/std",
+	"frame-system/std",
+
+	"sp-io/std",
+	"sp-std/std",
+	"sp-runtime/std",
+	"sp-npos-elections/std",
+	"sp-arithmetic/std",
+	"sp-election-providers/std",
+]
+runtime-benchmarks = [
+	"frame-benchmarking",
+	"rand",
+]