Companion for Trim compact solution for length during preparation (#2649)

* Companion for Trim compact solution for length during preparation

https://github.com/paritytech/substrate/pull/8317

* eliminate potential for overflow in OffchainSolutionLengthLimit

* Apply suggestions from code review

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

* update substrate: cargo update -p sp-io

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

polkadot/runtime/common/src/lib.rs

@@ -118,6 +118,14 @@ parameter_types! {
 		.max_extrinsic
 		.expect("Normal extrinsics have weight limit configured by default; qed")
 		.saturating_sub(BlockExecutionWeight::get());
+
+	/// A limit for off-chain phragmen unsigned solution length.
+	///
+	/// We allow up to 90% of the block's size to be consumed by the solution.
+	pub OffchainSolutionLengthLimit: u32 = Perbill::from_rational(90_u32, 100) *
+		*BlockLength::get()
+		.max
+		.get(DispatchClass::Normal);
 }
 
 /// Parameterized slow adjusting fee updated based on

polkadot/runtime/kusama/src/lib.rs

@@ -34,7 +34,8 @@ use primitives::v1::{
 use runtime_common::{
 	claims, SlowAdjustingFeeUpdate, CurrencyToVote,
 	impls::DealWithFees,
-	BlockHashCount, RocksDbWeight, BlockWeights, BlockLength, OffchainSolutionWeightLimit,
+	BlockHashCount, RocksDbWeight, BlockWeights, BlockLength,
+	OffchainSolutionWeightLimit, OffchainSolutionLengthLimit,
 	ParachainSessionKeyPlaceholder, AssignmentSessionKeyPlaceholder,
 };
 use sp_runtime::{
@@ -338,7 +339,8 @@ impl pallet_election_provider_multi_phase::Config for Runtime {
 	type UnsignedPhase = UnsignedPhase;
 	type SolutionImprovementThreshold = SolutionImprovementThreshold;
 	type MinerMaxIterations = MinerMaxIterations;
-	type MinerMaxWeight = OffchainSolutionWeightLimit; // For now use the one from staking.
+	type MinerMaxWeight = OffchainSolutionWeightLimit;
+	type MinerMaxLength = OffchainSolutionLengthLimit;
 	type MinerTxPriority = NposSolutionPriority;
 	type DataProvider = Staking;
 	type OnChainAccuracy = Perbill;

polkadot/runtime/polkadot/src/lib.rs

@@ -24,7 +24,8 @@ use pallet_transaction_payment::CurrencyAdapter;
 use runtime_common::{
 	claims, SlowAdjustingFeeUpdate, CurrencyToVote,
 	impls::DealWithFees,
-	BlockHashCount, RocksDbWeight, BlockWeights, BlockLength, OffchainSolutionWeightLimit,
+	BlockHashCount, RocksDbWeight, BlockWeights, BlockLength,
+	OffchainSolutionWeightLimit, OffchainSolutionLengthLimit,
 	ParachainSessionKeyPlaceholder, AssignmentSessionKeyPlaceholder,
 };
 
@@ -348,7 +349,8 @@ impl pallet_election_provider_multi_phase::Config for Runtime {
 	type UnsignedPhase = UnsignedPhase;
 	type SolutionImprovementThreshold = SolutionImprovementThreshold;
 	type MinerMaxIterations = MinerMaxIterations;
-	type MinerMaxWeight = OffchainSolutionWeightLimit; // For now use the one from staking.
+	type MinerMaxWeight = OffchainSolutionWeightLimit;
+	type MinerMaxLength = OffchainSolutionLengthLimit;
 	type MinerTxPriority = NposSolutionPriority;
 	type DataProvider = Staking;
 	type OnChainAccuracy = Perbill;

polkadot/runtime/westend/src/lib.rs

@@ -34,7 +34,8 @@ use runtime_common::{
 	mmr as mmr_common,
 	SlowAdjustingFeeUpdate, CurrencyToVote,
 	impls::ToAuthor,
-	BlockHashCount, BlockWeights, BlockLength, RocksDbWeight, OffchainSolutionWeightLimit,
+	BlockHashCount, BlockWeights, BlockLength, RocksDbWeight,
+	OffchainSolutionWeightLimit, OffchainSolutionLengthLimit,
 	ParachainSessionKeyPlaceholder, AssignmentSessionKeyPlaceholder,
 };
 use sp_runtime::{
@@ -365,7 +366,8 @@ impl pallet_election_provider_multi_phase::Config for Runtime {
 	type UnsignedPhase = UnsignedPhase;
 	type SolutionImprovementThreshold = SolutionImprovementThreshold;
 	type MinerMaxIterations = MinerMaxIterations;
-	type MinerMaxWeight = OffchainSolutionWeightLimit; // For now use the one from staking.
+	type MinerMaxWeight = OffchainSolutionWeightLimit;
+	type MinerMaxLength = OffchainSolutionLengthLimit;
 	type MinerTxPriority = NposSolutionPriority;
 	type DataProvider = Staking;
 	type OnChainAccuracy = Perbill;