Staking Payout Creates Controller (paritytech#6496)

* payout creates controller

* update benchmarks

* oops

* fix session benchmarks

* Update weights

* fix line width

frame/session/benchmarking/src/lib.rs

@@ -45,15 +45,15 @@ benchmarks! {
 
 	set_keys {
 		let n in 1 .. MAX_NOMINATIONS as u32;
-		let v_stash = create_validator_with_nominators::<T>(n, MAX_NOMINATIONS as u32)?;
+		let v_stash = create_validator_with_nominators::<T>(n, MAX_NOMINATIONS as u32, false)?;
 		let v_controller = pallet_staking::Module::<T>::bonded(&v_stash).ok_or("not stash")?;
 		let keys = T::Keys::default();
 		let proof: Vec<u8> = vec![0,1,2,3];
 	}: _(RawOrigin::Signed(v_controller), keys, proof)
 
 	purge_keys {
 		let n in 1 .. MAX_NOMINATIONS as u32;
-		let v_stash = create_validator_with_nominators::<T>(n, MAX_NOMINATIONS as u32)?;
+		let v_stash = create_validator_with_nominators::<T>(n, MAX_NOMINATIONS as u32, false)?;
 		let v_controller = pallet_staking::Module::<T>::bonded(&v_stash).ok_or("not stash")?;
 		let keys = T::Keys::default();
 		let proof: Vec<u8> = vec![0,1,2,3];

frame/staking/src/benchmarking.rs

@@ -47,7 +47,11 @@ fn add_slashing_spans<T: Trait>(who: &T::AccountId, spans: u32) {
 
 // This function generates one validator being nominated by n nominators, and returns the validator
 // stash account. It also starts an era and creates pending payouts.
-pub fn create_validator_with_nominators<T: Trait>(n: u32, upper_bound: u32) -> Result<T::AccountId, &'static str> {
+pub fn create_validator_with_nominators<T: Trait>(
+	n: u32,
+	upper_bound: u32,
+	dead: bool,
+) -> Result<T::AccountId, &'static str> {
 	let mut points_total = 0;
 	let mut points_individual = Vec::new();
 
@@ -65,7 +69,11 @@ pub fn create_validator_with_nominators<T: Trait>(n: u32, upper_bound: u32) -> R
 
 	// Give the validator n nominators, but keep total users in the system the same.
 	for i in 0 .. upper_bound {
-		let (_n_stash, n_controller) = create_stash_controller::<T>(u32::max_value() - i, 100)?;
+		let (_n_stash, n_controller) = if !dead {
+			create_stash_controller::<T>(u32::max_value() - i, 100)?
+		} else {
+			create_stash_and_dead_controller::<T>(u32::max_value() - i, 100)?
+		};
 		if i < n {
 			Staking::<T>::nominate(RawOrigin::Signed(n_controller.clone()).into(), vec![stash_lookup.clone()])?;
 		}
@@ -271,7 +279,8 @@ benchmarks! {
 
 	payout_stakers {
 		let n in 1 .. T::MaxNominatorRewardedPerValidator::get() as u32;
-		let validator = create_validator_with_nominators::<T>(n, T::MaxNominatorRewardedPerValidator::get() as u32)?;
+		let validator = create_validator_with_nominators::<T>(n, T::MaxNominatorRewardedPerValidator::get() as u32, true)?;
+
 		let current_era = CurrentEra::get().unwrap();
 		let caller = account("caller", 0, SEED);
 		let balance_before = T::Currency::free_balance(&validator);
@@ -282,6 +291,20 @@ benchmarks! {
 		assert!(balance_before < balance_after);
 	}
 
+	payout_stakers_alive_controller {
+		let n in 1 .. T::MaxNominatorRewardedPerValidator::get() as u32;
+		let validator = create_validator_with_nominators::<T>(n, T::MaxNominatorRewardedPerValidator::get() as u32, false)?;
+
+		let current_era = CurrentEra::get().unwrap();
+		let caller = account("caller", 0, SEED);
+		let balance_before = T::Currency::free_balance(&validator);
+	}: payout_stakers(RawOrigin::Signed(caller), validator.clone(), current_era)
+	verify {
+		// Validator has been paid!
+		let balance_after = T::Currency::free_balance(&validator);
+		assert!(balance_before < balance_after);
+	}
+
 	rebond {
 		let l in 1 .. MAX_UNLOCKING_CHUNKS as u32;
 		let (_, controller) = create_stash_controller::<T>(u, 100)?;
@@ -630,6 +653,7 @@ mod tests {
 			let validator_stash = create_validator_with_nominators::<Test>(
 				n,
 				<Test as Trait>::MaxNominatorRewardedPerValidator::get() as u32,
+				false,
 			).unwrap();
 
 			let current_era = CurrentEra::get().unwrap();
@@ -650,6 +674,7 @@ mod tests {
 			let validator_stash = create_validator_with_nominators::<Test>(
 				n,
 				<Test as Trait>::MaxNominatorRewardedPerValidator::get() as u32,
+				false,
 			).unwrap();
 
 			// Add 20 slashing spans
@@ -710,6 +735,7 @@ mod tests {
 			assert_ok!(test_benchmark_force_unstake::<Test>());
 			assert_ok!(test_benchmark_cancel_deferred_slash::<Test>());
 			assert_ok!(test_benchmark_payout_stakers::<Test>());
+			assert_ok!(test_benchmark_payout_stakers_alive_controller::<Test>());
 			assert_ok!(test_benchmark_rebond::<Test>());
 			assert_ok!(test_benchmark_set_history_depth::<Test>());
 			assert_ok!(test_benchmark_reap_stash::<Test>());

frame/staking/src/lib.rs

@@ -1978,15 +1978,17 @@ decl_module! {
 		/// - Contains a limited number of reads and writes.
 		/// -----------
 		/// N is the Number of payouts for the validator (including the validator)
-		/// Base Weight: 110 + 54.2 * N µs (Median Slopes)
+		/// Base Weight:
+		/// - Reward Destination Staked: 110 + 54.2 * N µs (Median Slopes)
+		/// - Reward Destination Controller (Creating): 120 + 41.95 * N µs (Median Slopes)
 		/// DB Weight:
 		/// - Read: EraElectionStatus, CurrentEra, HistoryDepth, ErasValidatorReward,
 		///         ErasStakersClipped, ErasRewardPoints, ErasValidatorPrefs (8 items)
 		/// - Read Each: Bonded, Ledger, Payee, Locks, System Account (5 items)
 		/// - Write Each: System Account, Locks, Ledger (3 items)
 		/// # </weight>
 		#[weight =
-			110 * WEIGHT_PER_MICROS
+			120 * WEIGHT_PER_MICROS
 			+ 54 * WEIGHT_PER_MICROS * Weight::from(T::MaxNominatorRewardedPerValidator::get())
 			+ T::DbWeight::get().reads(7)
 			+ T::DbWeight::get().reads(5)  * Weight::from(T::MaxNominatorRewardedPerValidator::get() + 1)
@@ -2395,7 +2397,7 @@ impl<T: Trait> Module<T> {
 		match dest {
 			RewardDestination::Controller => Self::bonded(stash)
 				.and_then(|controller|
-					T::Currency::deposit_into_existing(&controller, amount).ok()
+					Some(T::Currency::deposit_creating(&controller, amount))
 				),
 			RewardDestination::Stash =>
 				T::Currency::deposit_into_existing(stash, amount).ok(),

frame/staking/src/testing_utils.rs

@@ -51,6 +51,21 @@ pub fn create_stash_controller<T: Trait>(n: u32, balance_factor: u32)
 	return Ok((stash, controller))
 }
 
+/// Create a stash and controller pair, where the controller is dead, and payouts go to controller.
+/// This is used to test worst case payout scenarios.
+pub fn create_stash_and_dead_controller<T: Trait>(n: u32, balance_factor: u32)
+	-> Result<(T::AccountId, T::AccountId), &'static str>
+{
+	let stash = create_funded_user::<T>("stash", n, balance_factor);
+	// controller has no funds
+	let controller = create_funded_user::<T>("controller", n, 0);
+	let controller_lookup: <T::Lookup as StaticLookup>::Source = T::Lookup::unlookup(controller.clone());
+	let reward_destination = RewardDestination::Controller;
+	let amount = T::Currency::minimum_balance() * (balance_factor / 10).max(1).into();
+	Staking::<T>::bond(RawOrigin::Signed(stash.clone()).into(), controller_lookup, amount, reward_destination)?;
+	return Ok((stash, controller))
+}
+
 /// create `max` validators.
 pub fn create_validators<T: Trait>(
 	max: u32,

frame/staking/src/tests.rs

@@ -4501,3 +4501,33 @@ fn on_initialize_weight_is_correct() {
 		assert_eq!(final_weight, Staking::on_initialize(System::block_number()));
 	});
 }
+
+
+#[test]
+fn payout_creates_controller() {
+	// Here we will test validator can set `max_nominators_payout` and it works.
+	// We also test that `payout_extra_nominators` works.
+	ExtBuilder::default().has_stakers(false).build_and_execute(|| {
+		let balance = 1000;
+		// Create three validators:
+		bond_validator(11, 10, balance); // Default(64)
+
+		// Create a stash/controller pair
+		bond_nominator(1234, 1337, 100, vec![11]);
+
+		// kill controller
+		assert_ok!(Balances::transfer(Origin::signed(1337), 1234, 100));
+		assert_eq!(Balances::free_balance(1337), 0);
+
+		mock::start_era(1);
+		Staking::reward_by_ids(vec![(11, 1)]);
+		// Compute total payout now for whole duration as other parameter won't change
+		let total_payout_0 = current_total_payout_for_duration(3 * 1000);
+		assert!(total_payout_0 > 100); // Test is meaningful if reward something
+		mock::start_era(2);
+		assert_ok!(Staking::payout_stakers(Origin::signed(1337), 11, 1));
+
+		// Controller is created
+		assert!(Balances::free_balance(1337) > 0);
+	})
+}