Estimate call fee (#9395)

* Estimate call fee

* More fix

* Fix

* Update frame/support/src/traits/misc.rs

Co-authored-by: Zeke Mostov <32168567+emostov@users.noreply.github.com>

* try and fix fmt stuff

* fmt aain

Co-authored-by: Parity Benchmarking Bot <admin@parity.io>
Co-authored-by: Zeke Mostov <32168567+emostov@users.noreply.github.com>

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

@@ -237,7 +237,7 @@ use frame_support::{
 };
 use frame_system::{ensure_none, offchain::SendTransactionTypes};
 use sp_arithmetic::{
-	traits::{CheckedAdd, Zero},
+	traits::{CheckedAdd, Saturating, Zero},
 	UpperOf,
 };
 use sp_npos_elections::{
@@ -554,7 +554,7 @@ pub use pallet::*;
 #[frame_support::pallet]
 pub mod pallet {
 	use super::*;
-	use frame_support::pallet_prelude::*;
+	use frame_support::{pallet_prelude::*, traits::EstimateCallFee};
 	use frame_system::pallet_prelude::*;
 
 	#[pallet::config]
@@ -566,6 +566,9 @@ pub mod pallet {
 		/// Currency type.
 		type Currency: ReservableCurrency<Self::AccountId> + Currency<Self::AccountId>;
 
+		/// Something that can predict the fee of a call. Used to sensibly distribute rewards.
+		type EstimateCallFee: EstimateCallFee<Call<Self>, BalanceOf<Self>>;
+
 		/// Duration of the unsigned phase.
 		#[pallet::constant]
 		type UnsignedPhase: Get<Self::BlockNumber>;
@@ -973,7 +976,13 @@ pub mod pallet {
 
 			// create the submission
 			let deposit = Self::deposit_for(&solution, size);
-			let submission = SignedSubmission { who: who.clone(), deposit, solution };
+			let reward = {
+				let call = Call::submit(solution.clone(), num_signed_submissions);
+				let call_fee = T::EstimateCallFee::estimate_call_fee(&call, None.into());
+				T::SignedRewardBase::get().saturating_add(call_fee)
+			};
+
+			let submission = SignedSubmission { who: who.clone(), deposit, solution, reward };
 
 			// insert the submission if the queue has space or it's better than the weakest
 			// eject the weakest if the queue was full

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

@@ -261,7 +261,6 @@ parameter_types! {
 	pub static SignedDepositByte: Balance = 0;
 	pub static SignedDepositWeight: Balance = 0;
 	pub static SignedRewardBase: Balance = 7;
-	pub static SignedRewardMax: Balance = 10;
 	pub static SignedMaxWeight: Weight = BlockWeights::get().max_block;
 	pub static MinerMaxIterations: u32 = 5;
 	pub static MinerTxPriority: u64 = 100;
@@ -356,6 +355,7 @@ impl multi_phase::weights::WeightInfo for DualMockWeightInfo {
 impl crate::Config for Runtime {
 	type Event = Event;
 	type Currency = Balances;
+	type EstimateCallFee = frame_support::traits::ConstU32<8>;
 	type SignedPhase = SignedPhase;
 	type UnsignedPhase = UnsignedPhase;
 	type SolutionImprovementThreshold = SolutionImprovementThreshold;

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

@@ -51,6 +51,8 @@ pub struct SignedSubmission<AccountId, Balance: HasCompact, CompactSolution> {
 	pub deposit: Balance,
 	/// The raw solution itself.
 	pub solution: RawSolution<CompactSolution>,
+	/// The reward that should potentially be paid for this solution, if accepted.
+	pub reward: Balance,
 }
 
 impl<AccountId, Balance, CompactSolution> Ord
@@ -351,10 +353,8 @@ impl<T: Config> Pallet<T> {
 		let SolutionOrSnapshotSize { voters, targets } =
 			Self::snapshot_metadata().unwrap_or_default();
 
-		let reward = T::SignedRewardBase::get();
-
 		while let Some(best) = all_submissions.pop_last() {
-			let SignedSubmission { solution, who, deposit } = best;
+			let SignedSubmission { solution, who, deposit, reward } = best;
 			let active_voters = solution.compact.voter_count() as u32;
 			let feasibility_weight = {
 				// defensive only: at the end of signed phase, snapshot will exits.
@@ -567,7 +567,7 @@ mod tests {
 			assert_eq!(balances(&99), (95, 5));
 
 			assert!(MultiPhase::finalize_signed_phase().0);
-			assert_eq!(balances(&99), (100 + 7, 0));
+			assert_eq!(balances(&99), (100 + 7 + 8, 0));
 		})
 	}
 
@@ -616,7 +616,7 @@ mod tests {
 			assert!(MultiPhase::finalize_signed_phase().0);
 
 			// 99 is rewarded.
-			assert_eq!(balances(&99), (100 + 7, 0));
+			assert_eq!(balances(&99), (100 + 7 + 8, 0));
 			// 999 gets everything back.
 			assert_eq!(balances(&999), (100, 0));
 		})
@@ -807,7 +807,7 @@ mod tests {
 			assert!(MultiPhase::finalize_signed_phase().0);
 
 			// 99 is rewarded.
-			assert_eq!(balances(&99), (100 + 7, 0));
+			assert_eq!(balances(&99), (100 + 7 + 8, 0));
 			// 999 is slashed.
 			assert_eq!(balances(&999), (95, 0));
 			// 9999 gets everything back.