Custom Codec Implementation for NPoS Election

frame/staking/src/lib.rs

@@ -326,7 +326,7 @@ use frame_system::{
 };
 use sp_npos_elections::{
 	ExtendedBalance, Assignment, ElectionScore, ElectionResult as PrimitiveElectionResult,
-	build_support_map, evaluate_support, seq_phragmen, generate_compact_solution_type,
+	build_support_map, evaluate_support, seq_phragmen, generate_solution_type,
 	is_score_better, VotingLimit, SupportMap, VoteWeight,
 };
 
@@ -369,19 +369,10 @@ pub type EraIndex = u32;
 pub type RewardPoint = u32;
 
 // Note: Maximum nomination limit is set here -- 16.
-generate_compact_solution_type!(pub GenericCompactAssignments, 16);
-
-/// Information regarding the active era (era in used in session).
-#[derive(Encode, Decode, RuntimeDebug)]
-pub struct ActiveEraInfo {
-	/// Index of era.
-	pub index: EraIndex,
-	/// Moment of start expressed as millisecond from `$UNIX_EPOCH`.
-	///
-	/// Start can be none if start hasn't been set for the era yet,
-	/// Start is set on the first on_finalize of the era to guarantee usage of `Time`.
-	start: Option<u64>,
-}
+generate_solution_type!(
+	#[compact]
+	pub struct CompactAssignments::<NominatorIndex, ValidatorIndex, OffchainAccuracy>(16)
+);
 
 /// Accuracy used for on-chain election.
 pub type ChainAccuracy = Perbill;
@@ -393,15 +384,23 @@ pub type OffchainAccuracy = PerU16;
 pub type BalanceOf<T> =
 	<<T as Trait>::Currency as Currency<<T as frame_system::Trait>::AccountId>>::Balance;
 
-/// The compact type for election solutions.
-pub type CompactAssignments =
-	GenericCompactAssignments<NominatorIndex, ValidatorIndex, OffchainAccuracy>;
-
 type PositiveImbalanceOf<T> =
 	<<T as Trait>::Currency as Currency<<T as frame_system::Trait>::AccountId>>::PositiveImbalance;
 type NegativeImbalanceOf<T> =
 	<<T as Trait>::Currency as Currency<<T as frame_system::Trait>::AccountId>>::NegativeImbalance;
 
+/// Information regarding the active era (era in used in session).
+#[derive(Encode, Decode, RuntimeDebug)]
+pub struct ActiveEraInfo {
+	/// Index of era.
+	pub index: EraIndex,
+	/// Moment of start expressed as millisecond from `$UNIX_EPOCH`.
+	///
+	/// Start can be none if start hasn't been set for the era yet,
+	/// Start is set on the first on_finalize of the era to guarantee usage of `Time`.
+	start: Option<u64>,
+}
+
 /// Reward points of an era. Used to split era total payout between validators.
 ///
 /// This points will be used to reward validators and their respective nominators.

primitives/arithmetic/fuzzer/src/per_thing_rational.rs

@@ -118,6 +118,5 @@ fn assert_per_thing_equal_error<P: PerThing>(a: P, b: P, err: u128) {
 	let a_abs = a.deconstruct().saturated_into::<u128>();
 	let b_abs = b.deconstruct().saturated_into::<u128>();
 	let diff = a_abs.max(b_abs) - a_abs.min(b_abs);
-	dbg!(&diff);
 	assert!(diff <= err, "{:?} !~ {:?}", a, b);
 }

primitives/npos-elections/compact/src/assignment.rs

@@ -15,20 +15,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//! Code generation for the ratio assignment type.
+//! Code generation for the ratio assignment type' compact representation.
 
 use crate::field_name_for;
 use proc_macro2::TokenStream as TokenStream2;
-use syn::GenericArgument;
 use quote::quote;
 
 fn from_impl(count: usize) -> TokenStream2 {
 	let from_impl_single = {
 		let name = field_name_for(1);
 		quote!(1 => compact.#name.push(
 			(
-				index_of_voter(&who).ok_or(_phragmen::Error::CompactInvalidIndex)?,
-				index_of_target(&distribution[0].0).ok_or(_phragmen::Error::CompactInvalidIndex)?,
+				index_of_voter(&who).or_invalid_index()?,
+				index_of_target(&distribution[0].0).or_invalid_index()?,
 			)
 		),)
 	};
@@ -37,29 +36,29 @@ fn from_impl(count: usize) -> TokenStream2 {
 		let name = field_name_for(2);
 		quote!(2 => compact.#name.push(
 			(
-				index_of_voter(&who).ok_or(_phragmen::Error::CompactInvalidIndex)?,
+				index_of_voter(&who).or_invalid_index()?,
 				(
-					index_of_target(&distribution[0].0).ok_or(_phragmen::Error::CompactInvalidIndex)?,
+					index_of_target(&distribution[0].0).or_invalid_index()?,
 					distribution[0].1,
 				),
-				index_of_target(&distribution[1].0).ok_or(_phragmen::Error::CompactInvalidIndex)?,
+				index_of_target(&distribution[1].0).or_invalid_index()?,
 			)
 		),)
 	};
 
 	let from_impl_rest = (3..=count).map(|c| {
 		let inner = (0..c-1).map(|i|
-			quote!((index_of_target(&distribution[#i].0).ok_or(_phragmen::Error::CompactInvalidIndex)?, distribution[#i].1),)
+			quote!((index_of_target(&distribution[#i].0).or_invalid_index()?, distribution[#i].1),)
 		).collect::<TokenStream2>();
 
 		let field_name = field_name_for(c);
 		let last_index = c - 1;
-		let last = quote!(index_of_target(&distribution[#last_index].0).ok_or(_phragmen::Error::CompactInvalidIndex)?);
+		let last = quote!(index_of_target(&distribution[#last_index].0).or_invalid_index()?);
 
 		quote!(
 			#c => compact.#field_name.push(
 				(
-					index_of_voter(&who).ok_or(_phragmen::Error::CompactInvalidIndex)?,
+					index_of_voter(&who).or_invalid_index()?,
 					[#inner],
 					#last,
 				)
@@ -74,15 +73,15 @@ fn from_impl(count: usize) -> TokenStream2 {
 	)
 }
 
-fn into_impl(count: usize) -> TokenStream2 {
+fn into_impl(count: usize, per_thing: syn::Type) -> TokenStream2 {
 	let into_impl_single = {
 		let name = field_name_for(1);
 		quote!(
 			for (voter_index, target_index) in self.#name {
 				assignments.push(_phragmen::Assignment {
-					who: voter_at(voter_index).ok_or(_phragmen::Error::CompactInvalidIndex)?,
+					who: voter_at(voter_index).or_invalid_index()?,
 					distribution: vec![
-						(target_at(target_index).ok_or(_phragmen::Error::CompactInvalidIndex)?, Accuracy::one())
+						(target_at(target_index).or_invalid_index()?, #per_thing::one())
 					],
 				})
 			}
@@ -93,21 +92,21 @@ fn into_impl(count: usize) -> TokenStream2 {
 		let name = field_name_for(2);
 		quote!(
 			for (voter_index, (t1_idx, p1), t2_idx) in self.#name {
-				if p1 >= Accuracy::one() {
+				if p1 >= #per_thing::one() {
 					return Err(_phragmen::Error::CompactStakeOverflow);
 				}
 
 				// defensive only. Since Percent doesn't have `Sub`.
 				let p2 = _phragmen::sp_arithmetic::traits::Saturating::saturating_sub(
-					Accuracy::one(),
+					#per_thing::one(),
 					p1,
 				);
 
 				assignments.push( _phragmen::Assignment {
-					who: voter_at(voter_index).ok_or(_phragmen::Error::CompactInvalidIndex)?,
+					who: voter_at(voter_index).or_invalid_index()?,
 					distribution: vec![
-						(target_at(t1_idx).ok_or(_phragmen::Error::CompactInvalidIndex)?, p1),
-						(target_at(t2_idx).ok_or(_phragmen::Error::CompactInvalidIndex)?, p2),
+						(target_at(t1_idx).or_invalid_index()?, p1),
+						(target_at(t2_idx).or_invalid_index()?, p2),
 					]
 				});
 			}
@@ -118,30 +117,30 @@ fn into_impl(count: usize) -> TokenStream2 {
 		let name = field_name_for(c);
 		quote!(
 			for (voter_index, inners, t_last_idx) in self.#name {
-				let mut sum = Accuracy::zero();
+				let mut sum = #per_thing::zero();
 				let mut inners_parsed = inners
 					.iter()
 					.map(|(ref t_idx, p)| {
 						sum = _phragmen::sp_arithmetic::traits::Saturating::saturating_add(sum, *p);
-						let target = target_at(*t_idx).ok_or(_phragmen::Error::CompactInvalidIndex)?;
+						let target = target_at(*t_idx).or_invalid_index()?;
 						Ok((target, *p))
 					})
-					.collect::<Result<Vec<(A, Accuracy)>, _phragmen::Error>>()?;
+					.collect::<Result<Vec<(A, #per_thing)>, _phragmen::Error>>()?;
 
-				if sum >= Accuracy::one() {
+				if sum >= #per_thing::one() {
 					return Err(_phragmen::Error::CompactStakeOverflow);
 				}
 
 				// defensive only. Since Percent doesn't have `Sub`.
 				let p_last = _phragmen::sp_arithmetic::traits::Saturating::saturating_sub(
-					Accuracy::one(),
+					#per_thing::one(),
 					sum,
 				);
 
-				inners_parsed.push((target_at(t_last_idx).ok_or(_phragmen::Error::CompactInvalidIndex)?, p_last));
+				inners_parsed.push((target_at(t_last_idx).or_invalid_index()?, p_last));
 
 				assignments.push(_phragmen::Assignment {
-					who: voter_at(voter_index).ok_or(_phragmen::Error::CompactInvalidIndex)?,
+					who: voter_at(voter_index).or_invalid_index()?,
 					distribution: inners_parsed,
 				});
 			}
@@ -157,39 +156,28 @@ fn into_impl(count: usize) -> TokenStream2 {
 
 pub(crate) fn assignment(
 	ident: syn::Ident,
-	voter_type: GenericArgument,
-	target_type: GenericArgument,
+	voter_type: syn::Type,
+	target_type: syn::Type,
+	weight_type: syn::Type,
 	count: usize,
 ) -> TokenStream2 {
-
 	let from_impl = from_impl(count);
-	let into_impl = into_impl(count);
+	let into_impl = into_impl(count, weight_type.clone());
 
 	quote!(
-		impl<
-			#voter_type: _phragmen::codec::Codec + Default + Copy,
-			#target_type: _phragmen::codec::Codec + Default + Copy,
-			Accuracy:
-				_phragmen::codec::Codec + Default + Clone + _phragmen::sp_arithmetic::PerThing +
-				PartialOrd,
-		>
-		#ident<#voter_type, #target_type, Accuracy>
-		{
+		use _phragmen::__OrInvalidIndex;
+		impl #ident {
 			pub fn from_assignment<FV, FT, A>(
-				assignments: Vec<_phragmen::Assignment<A, Accuracy>>,
+				assignments: Vec<_phragmen::Assignment<A, #weight_type>>,
 				index_of_voter: FV,
 				index_of_target: FT,
 			) -> Result<Self, _phragmen::Error>
 				where
+					A: _phragmen::IdentifierT,
 					for<'r> FV: Fn(&'r A) -> Option<#voter_type>,
 					for<'r> FT: Fn(&'r A) -> Option<#target_type>,
-					A: _phragmen::IdentifierT,
 			{
-				let mut compact: #ident<
-					#voter_type,
-					#target_type,
-					Accuracy,
-				> = Default::default();
+				let mut compact: #ident = Default::default();
 
 				for _phragmen::Assignment { who, distribution } in assignments {
 					match distribution.len() {
@@ -207,8 +195,8 @@ pub(crate) fn assignment(
 				self,
 				voter_at: impl Fn(#voter_type) -> Option<A>,
 				target_at: impl Fn(#target_type) -> Option<A>,
-			) -> Result<Vec<_phragmen::Assignment<A, Accuracy>>, _phragmen::Error> {
-				let mut assignments: Vec<_phragmen::Assignment<A, Accuracy>> = Default::default();
+			) -> Result<Vec<_phragmen::Assignment<A, #weight_type>>, _phragmen::Error> {
+				let mut assignments: Vec<_phragmen::Assignment<A, #weight_type>> = Default::default();
 				#into_impl
 				Ok(assignments)
 			}