Staking: Add deprecate_controller_batch AdminOrigin call (#2589)

Partially Addresses #2500

Adds a `deprecate_controller_batch` call to the staking pallet that is
callable by `Root` and `StakingAdmin`. To be used for controller account
deprecation and removed thereafter. Adds
`MaxControllersDeprecationBatch` pallet constant that defines max
possible deprecations per call.

- [x] Add `deprecate_controller_batch` call, and
`MaxControllersInDeprecationBatch` constant.
- [x] Add tests, benchmark, weights. Tests that weight is only consumed
if unique pair.
- [x] Adds `StakingAdmin` origin to staking's `AdminOrigin` type in
westend runtime.
- [x] Determined that worst case 5,900 deprecations does fit into
`maxBlock` `proofSize` and `refTime` in both normal and operational
thresholds, meaning we can deprecate all controllers for each network in
one call.

## Block Weights

By querying `consts.system.blockWeights` we can see that the
`deprecate_controller_batch` weights fit within the `normal` threshold
on Polkadot.

#### `controller_deprecation_batch` where i = 5900:
#### Ref time: 69,933,325,300
#### Proof size: 21,040,390

### Polkadot 

```
// consts.query.blockWeights

maxBlock: {
        refTime: 2,000,000,000,000
        proofSize: 18,446,744,073,709,551,615
}
normal: {
 maxExtrinsic: {
	refTime: 1,479,873,955,000
	proofSize: 13,650,590,614,545,068,195
 }
 maxTotal: {
	refTime: 1,500,000,000,000
	proofSize: 13,835,058,055,282,163,711
 }
}
```

### Kusama

```
// consts.query.blockWeights

  maxBlock: {
    refTime: 2,000,000,000,000
    proofSize: 18,446,744,073,709,551,615
  }
    normal: {
      maxExtrinsic: {
        refTime: 1,479,875,294,000
        proofSize: 13,650,590,614,545,068,195
      }
      maxTotal: {
        refTime: 1,500,000,000,000
        proofSize: 13,835,058,055,282,163,711
      }
}
```

---------

Co-authored-by: command-bot <>
Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>

polkadot/runtime/test-runtime/src/lib.rs

@@ -356,6 +356,7 @@ impl pallet_staking::Config for Runtime {
 	type TargetList = pallet_staking::UseValidatorsMap<Runtime>;
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<MAX_QUOTA_NOMINATIONS>;
 	type MaxUnlockingChunks = frame_support::traits::ConstU32<32>;
+	type MaxControllersInDeprecationBatch = ConstU32<5900>;
 	type HistoryDepth = frame_support::traits::ConstU32<84>;
 	type BenchmarkingConfig = runtime_common::StakingBenchmarkingConfig;
 	type EventListeners = ();

polkadot/runtime/westend/src/lib.rs

@@ -672,6 +672,7 @@ parameter_types! {
 	pub const MaxNominators: u32 = 64;
 	pub const OffendingValidatorsThreshold: Perbill = Perbill::from_percent(17);
 	pub const MaxNominations: u32 = <NposCompactSolution16 as frame_election_provider_support::NposSolution>::LIMIT as u32;
+	pub const MaxControllersInDeprecationBatch: u32 = 751;
 }
 
 impl pallet_staking::Config for Runtime {
@@ -686,7 +687,7 @@ impl pallet_staking::Config for Runtime {
 	type SessionsPerEra = SessionsPerEra;
 	type BondingDuration = BondingDuration;
 	type SlashDeferDuration = SlashDeferDuration;
-	type AdminOrigin = EnsureRoot<AccountId>;
+	type AdminOrigin = EitherOf<EnsureRoot<AccountId>, StakingAdmin>;
 	type SessionInterface = Self;
 	type EraPayout = pallet_staking::ConvertCurve<RewardCurve>;
 	type MaxExposurePageSize = MaxExposurePageSize;
@@ -699,6 +700,7 @@ impl pallet_staking::Config for Runtime {
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<{ MaxNominations::get() }>;
 	type MaxUnlockingChunks = frame_support::traits::ConstU32<32>;
 	type HistoryDepth = frame_support::traits::ConstU32<84>;
+	type MaxControllersInDeprecationBatch = MaxControllersInDeprecationBatch;
 	type BenchmarkingConfig = runtime_common::StakingBenchmarkingConfig;
 	type EventListeners = NominationPools;
 	type WeightInfo = weights::pallet_staking::WeightInfo<Runtime>;

substrate/bin/node/runtime/src/lib.rs

@@ -632,6 +632,7 @@ parameter_types! {
 	pub const RewardCurve: &'static PiecewiseLinear<'static> = &REWARD_CURVE;
 	pub const MaxNominators: u32 = 64;
 	pub const OffendingValidatorsThreshold: Perbill = Perbill::from_percent(17);
+	pub const MaxControllersInDeprecationBatch: u32 = 5900;
 	pub OffchainRepeat: BlockNumber = 5;
 	pub HistoryDepth: u32 = 84;
 }
@@ -674,6 +675,7 @@ impl pallet_staking::Config for Runtime {
 	// This a placeholder, to be introduced in the next PR as an instance of bags-list
 	type TargetList = pallet_staking::UseValidatorsMap<Self>;
 	type MaxUnlockingChunks = ConstU32<32>;
+	type MaxControllersInDeprecationBatch = MaxControllersInDeprecationBatch;
 	type HistoryDepth = HistoryDepth;
 	type EventListeners = NominationPools;
 	type WeightInfo = pallet_staking::weights::SubstrateWeight<Runtime>;

substrate/frame/babe/src/mock.rs

@@ -183,6 +183,7 @@ impl pallet_staking::Config for Test {
 	type TargetList = pallet_staking::UseValidatorsMap<Self>;
 	type NominationsQuota = FixedNominationsQuota<16>;
 	type MaxUnlockingChunks = ConstU32<32>;
+	type MaxControllersInDeprecationBatch = ConstU32<100>;
 	type HistoryDepth = ConstU32<84>;
 	type EventListeners = ();
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;

substrate/frame/beefy/src/mock.rs

@@ -201,6 +201,7 @@ impl pallet_staking::Config for Test {
 	type TargetList = pallet_staking::UseValidatorsMap<Self>;
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<16>;
 	type MaxUnlockingChunks = ConstU32<32>;
+	type MaxControllersInDeprecationBatch = ConstU32<100>;
 	type HistoryDepth = ConstU32<84>;
 	type EventListeners = ();
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;

substrate/frame/election-provider-multi-phase/test-staking-e2e/src/mock.rs

@@ -276,6 +276,7 @@ impl pallet_staking::Config for Runtime {
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<MAX_QUOTA_NOMINATIONS>;
 	type TargetList = pallet_staking::UseValidatorsMap<Self>;
 	type MaxUnlockingChunks = ConstU32<32>;
+	type MaxControllersInDeprecationBatch = ConstU32<100>;
 	type HistoryDepth = HistoryDepth;
 	type EventListeners = ();
 	type WeightInfo = pallet_staking::weights::SubstrateWeight<Runtime>;

substrate/frame/fast-unstake/src/mock.rs

@@ -142,6 +142,7 @@ impl pallet_staking::Config for Runtime {
 	type TargetList = pallet_staking::UseValidatorsMap<Self>;
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<16>;
 	type MaxUnlockingChunks = ConstU32<32>;
+	type MaxControllersInDeprecationBatch = ConstU32<100>;
 	type EventListeners = ();
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;
 	type WeightInfo = ();

substrate/frame/grandpa/src/mock.rs

@@ -206,6 +206,7 @@ impl pallet_staking::Config for Test {
 	type TargetList = pallet_staking::UseValidatorsMap<Self>;
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<16>;
 	type MaxUnlockingChunks = ConstU32<32>;
+	type MaxControllersInDeprecationBatch = ConstU32<100>;
 	type HistoryDepth = ConstU32<84>;
 	type EventListeners = ();
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;

substrate/frame/nomination-pools/benchmarking/src/mock.rs

@@ -119,6 +119,7 @@ impl pallet_staking::Config for Runtime {
 	type VoterList = VoterList;
 	type TargetList = pallet_staking::UseValidatorsMap<Self>;
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<16>;
+	type MaxControllersInDeprecationBatch = ConstU32<100>;
 	type MaxUnlockingChunks = ConstU32<32>;
 	type HistoryDepth = ConstU32<84>;
 	type EventListeners = Pools;

substrate/frame/nomination-pools/test-staking/src/mock.rs

@@ -134,6 +134,7 @@ impl pallet_staking::Config for Runtime {
 	type TargetList = pallet_staking::UseValidatorsMap<Self>;
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<16>;
 	type MaxUnlockingChunks = ConstU32<32>;
+	type MaxControllersInDeprecationBatch = ConstU32<100>;
 	type HistoryDepth = ConstU32<84>;
 	type EventListeners = Pools;
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;

substrate/frame/offences/benchmarking/src/mock.rs

@@ -185,6 +185,7 @@ impl pallet_staking::Config for Test {
 	type TargetList = pallet_staking::UseValidatorsMap<Self>;
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<16>;
 	type MaxUnlockingChunks = ConstU32<32>;
+	type MaxControllersInDeprecationBatch = ConstU32<100>;
 	type HistoryDepth = ConstU32<84>;
 	type EventListeners = ();
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;

substrate/frame/root-offences/src/mock.rs

@@ -188,6 +188,7 @@ impl pallet_staking::Config for Test {
 	type NominationsQuota = pallet_staking::FixedNominationsQuota<16>;
 	type MaxUnlockingChunks = ConstU32<32>;
 	type HistoryDepth = ConstU32<84>;
+	type MaxControllersInDeprecationBatch = ConstU32<100>;
 	type VoterList = pallet_staking::UseNominatorsAndValidatorsMap<Self>;
 	type EventListeners = ();
 	type BenchmarkingConfig = pallet_staking::TestBenchmarkingConfig;

substrate/frame/session/benchmarking/src/mock.rs

@@ -179,6 +179,7 @@ impl pallet_staking::Config for Test {
 	type ElectionProvider = onchain::OnChainExecution<OnChainSeqPhragmen>;
 	type GenesisElectionProvider = Self::ElectionProvider;
 	type MaxUnlockingChunks = ConstU32<32>;
+	type MaxControllersInDeprecationBatch = ConstU32<100>;
 	type HistoryDepth = ConstU32<84>;
 	type VoterList = pallet_staking::UseNominatorsAndValidatorsMap<Self>;
 	type TargetList = pallet_staking::UseValidatorsMap<Self>;

substrate/frame/staking/src/benchmarking.rs

@@ -25,6 +25,7 @@ use codec::Decode;
 use frame_election_provider_support::{bounds::DataProviderBounds, SortedListProvider};
 use frame_support::{
 	pallet_prelude::*,
+	storage::bounded_vec::BoundedVec,
 	traits::{Currency, Get, Imbalance, UnfilteredDispatchable},
 };
 use sp_runtime::{
@@ -525,6 +526,39 @@ benchmarks! {
 		assert_eq!(Invulnerables::<T>::get().len(), v as usize);
 	}
 
+	deprecate_controller_batch {
+		// We pass a dynamic number of controllers to the benchmark, up to
+		// `MaxControllersInDeprecationBatch`.
+		let i in 0 .. T::MaxControllersInDeprecationBatch::get();
+
+		let mut controllers: Vec<_> = vec![];
+		let mut stashes: Vec<_> = vec![];
+		for n in 0..i as u32 {
+			let (stash, controller) = create_unique_stash_controller::<T>(
+				n,
+				100,
+				RewardDestination::Staked,
+				false
+			)?;
+			controllers.push(controller);
+			stashes.push(stash);
+		}
+		let bounded_controllers: BoundedVec<_, T::MaxControllersInDeprecationBatch> =
+			BoundedVec::try_from(controllers.clone()).unwrap();
+	}: _(RawOrigin::Root, bounded_controllers)
+	verify {
+		for n in 0..i as u32 {
+			let stash = &stashes[n as usize];
+			let controller = &controllers[n as usize];
+			// Ledger no longer keyed by controller.
+			assert_eq!(Ledger::<T>::get(controller), None);
+			// Bonded now maps to the stash.
+			assert_eq!(Bonded::<T>::get(stash), Some(stash.clone()));
+			// Ledger is now keyed by stash.
+			assert_eq!(Ledger::<T>::get(stash).unwrap().stash, *stash);
+		}
+	}
+
 	force_unstake {
 		// Slashing Spans
 		let s in 0 .. MAX_SPANS;

substrate/frame/staking/src/mock.rs

@@ -122,6 +122,7 @@ parameter_types! {
 	pub static SlashDeferDuration: EraIndex = 0;
 	pub static Period: BlockNumber = 5;
 	pub static Offset: BlockNumber = 0;
+	pub static MaxControllersInDeprecationBatch: u32 = 5900;
 }
 
 #[derive_impl(frame_system::config_preludes::TestDefaultConfig as frame_system::DefaultConfig)]
@@ -316,6 +317,7 @@ impl crate::pallet::pallet::Config for Test {
 	type NominationsQuota = WeightedNominationsQuota<16>;
 	type MaxUnlockingChunks = MaxUnlockingChunks;
 	type HistoryDepth = HistoryDepth;
+	type MaxControllersInDeprecationBatch = MaxControllersInDeprecationBatch;
 	type EventListeners = EventListenerMock;
 	type BenchmarkingConfig = TestBenchmarkingConfig;
 	type WeightInfo = ();

substrate/frame/staking/src/pallet/mod.rs

@@ -269,6 +269,9 @@ pub mod pallet {
 		#[pallet::constant]
 		type MaxUnlockingChunks: Get<u32>;
 
+		/// The maximum amount of controller accounts that can be deprecated in one call.
+		type MaxControllersInDeprecationBatch: Get<u32>;
+
 		/// Something that listens to staking updates and performs actions based on the data it
 		/// receives.
 		///
@@ -1323,18 +1326,17 @@ pub mod pallet {
 		pub fn set_controller(origin: OriginFor<T>) -> DispatchResult {
 			let stash = ensure_signed(origin)?;
 
-			// the bonded map and ledger are mutated directly as this extrinsic is related to a
+			// The bonded map and ledger are mutated directly as this extrinsic is related to a
 			// (temporary) passive migration.
 			Self::ledger(StakingAccount::Stash(stash.clone())).map(|ledger| {
 				let controller = ledger.controller()
                     .defensive_proof("Ledger's controller field didn't exist. The controller should have been fetched using StakingLedger.")
                     .ok_or(Error::<T>::NotController)?;
 
 				if controller == stash {
-					// stash is already its own controller.
+					// Stash is already its own controller.
 					return Err(Error::<T>::AlreadyPaired.into())
 				}
-				// update bond and ledger.
 				<Ledger<T>>::remove(controller);
 				<Bonded<T>>::insert(&stash, &stash);
 				<Ledger<T>>::insert(&stash, ledger);
@@ -1920,6 +1922,54 @@ pub mod pallet {
 
 			Ok(Pays::No.into())
 		}
+
+		/// Updates a batch of controller accounts to their corresponding stash account if they are
+		/// not the same. Ignores any controller accounts that do not exist, and does not operate if
+		/// the stash and controller are already the same.
+		///
+		/// Effects will be felt instantly (as soon as this function is completed successfully).
+		///
+		/// The dispatch origin must be `T::AdminOrigin`.
+		#[pallet::call_index(28)]
+		#[pallet::weight(T::WeightInfo::deprecate_controller_batch(controllers.len() as u32))]
+		pub fn deprecate_controller_batch(
+			origin: OriginFor<T>,
+			controllers: BoundedVec<T::AccountId, T::MaxControllersInDeprecationBatch>,
+		) -> DispatchResultWithPostInfo {
+			T::AdminOrigin::ensure_origin(origin)?;
+
+			// Ignore controllers that do not exist or are already the same as stash.
+			let filtered_batch_with_ledger: Vec<_> = controllers
+				.iter()
+				.filter_map(|controller| {
+					let ledger = Self::ledger(StakingAccount::Controller(controller.clone()));
+					ledger.ok().map_or(None, |ledger| {
+						// If the controller `RewardDestination` is still the deprecated
+						// `Controller` variant, skip deprecating this account.
+						let payee_deprecated = Payee::<T>::get(&ledger.stash) == {
+							#[allow(deprecated)]
+							RewardDestination::Controller
+						};
+
+						if ledger.stash != *controller && !payee_deprecated {
+							Some((controller.clone(), ledger))
+						} else {
+							None
+						}
+					})
+				})
+				.collect();
+
+			// Update unique pairs.
+			for (controller, ledger) in filtered_batch_with_ledger {
+				let stash = ledger.stash.clone();
+
+				<Bonded<T>>::insert(&stash, &stash);
+				<Ledger<T>>::remove(controller);
+				<Ledger<T>>::insert(stash, ledger);
+			}
+			Ok(Some(T::WeightInfo::deprecate_controller_batch(controllers.len() as u32)).into())
+		}
 	}
 }