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rework staking::reap_stash (#10178)
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* rework reap_stash

* Update frame/staking/src/pallet/mod.rs

Co-authored-by: Zeke Mostov <z.mostov@gmail.com>

* Update frame/staking/src/pallet/mod.rs

Co-authored-by: Zeke Mostov <z.mostov@gmail.com>

* Update frame/staking/src/pallet/mod.rs

Co-authored-by: Zeke Mostov <z.mostov@gmail.com>

* Fix

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>
Co-authored-by: Zeke Mostov <z.mostov@gmail.com>
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@kianenigma @shawntabrizi @emostov
3 people authored Nov 14, 2021
1 parent ee8ac3a commit 1b646b2
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Showing 3 changed files with 50 additions and 113 deletions.
5 changes: 2 additions & 3 deletions frame/staking/src/benchmarking.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ use frame_support::{
traits::{Currency, CurrencyToVote, Get, Imbalance},
};
use sp_runtime::{
traits::{StaticLookup, Zero},
traits::{Bounded, One, StaticLookup, Zero},
Perbill, Percent,
};
use sp_staking::SessionIndex;
Expand All @@ -38,7 +38,6 @@ pub use frame_benchmarking::{
account, benchmarks, impl_benchmark_test_suite, whitelist_account, whitelisted_caller,
};
use frame_system::RawOrigin;
use sp_runtime::traits::{Bounded, One};

const SEED: u32 = 0;
const MAX_SPANS: u32 = 100;
Expand Down Expand Up @@ -695,7 +694,7 @@ benchmarks! {
let stash = scenario.origin_stash1.clone();

add_slashing_spans::<T>(&stash, s);
T::Currency::make_free_balance_be(&stash, T::Currency::minimum_balance());
Ledger::<T>::insert(&controller, StakingLedger { active: T::Currency::minimum_balance() - One::one(), total: T::Currency::minimum_balance() - One::one(), ..Default::default() });

assert!(Bonded::<T>::contains_key(&stash));
assert!(T::SortedListProvider::contains(&stash));
Expand Down
40 changes: 22 additions & 18 deletions frame/staking/src/pallet/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1425,33 +1425,37 @@ pub mod pallet {
Ok(())
}

/// Remove all data structure concerning a staker/stash once its balance is at the minimum.
/// This is essentially equivalent to `withdraw_unbonded` except it can be called by anyone
/// and the target `stash` must have no funds left beyond the ED.
/// Remove all data structures concerning a staker/stash once it is at a state where it can
/// be considered `dust` in the staking system. The requirements are:
///
/// This can be called from any origin.
/// 1. the `total_balance` of the stash is below existential deposit.
/// 2. or, the `ledger.total` of the stash is below existential deposit.
///
/// - `stash`: The stash account to reap. Its balance must be zero.
/// The former can happen in cases like a slash; the latter when a fully unbonded account
/// is still receiving staking rewards in `RewardDestination::Staked`.
///
/// # <weight>
/// Complexity: O(S) where S is the number of slashing spans on the account.
/// DB Weight:
/// - Reads: Stash Account, Bonded, Slashing Spans, Locks
/// - Writes: Bonded, Slashing Spans (if S > 0), Ledger, Payee, Validators, Nominators,
/// Stash Account, Locks
/// - Writes Each: SpanSlash * S
/// # </weight>
/// It can be called by anyone, as long as `stash` meets the above requirements.
///
/// Refunds the transaction fees upon successful execution.
#[pallet::weight(T::WeightInfo::reap_stash(*num_slashing_spans))]
pub fn reap_stash(
_origin: OriginFor<T>,
origin: OriginFor<T>,
stash: T::AccountId,
num_slashing_spans: u32,
) -> DispatchResult {
let at_minimum = T::Currency::total_balance(&stash) == T::Currency::minimum_balance();
ensure!(at_minimum, Error::<T>::FundedTarget);
) -> DispatchResultWithPostInfo {
let _ = ensure_signed(origin)?;

let ed = T::Currency::minimum_balance();
let reapable = T::Currency::total_balance(&stash) < ed ||
Self::ledger(Self::bonded(stash.clone()).ok_or(Error::<T>::NotStash)?)
.map(|l| l.total)
.unwrap_or_default() < ed;
ensure!(reapable, Error::<T>::FundedTarget);

Self::kill_stash(&stash, num_slashing_spans)?;
T::Currency::remove_lock(STAKING_ID, &stash);
Ok(())

Ok(Pays::No.into())
}

/// Remove the given nominations from the calling validator.
Expand Down
118 changes: 26 additions & 92 deletions frame/staking/src/tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1633,115 +1633,49 @@ fn reward_to_stake_works() {
}

#[test]
fn on_free_balance_zero_stash_removes_validator() {
// Tests that validator storage items are cleaned up when stash is empty
// Tests that storage items are untouched when controller is empty
fn reap_stash_works() {
ExtBuilder::default()
.existential_deposit(10)
.balance_factor(10)
.build_and_execute(|| {
// Check the balance of the validator account
// given
assert_eq!(Balances::free_balance(10), 10);
// Check the balance of the stash account
assert_eq!(Balances::free_balance(11), 10 * 1000);
// Check these two accounts are bonded
assert_eq!(Staking::bonded(&11), Some(10));

// Set payee information
assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Stash));

// Check storage items that should be cleaned up
assert!(<Ledger<Test>>::contains_key(&10));
assert!(<Bonded<Test>>::contains_key(&11));
assert!(<Validators<Test>>::contains_key(&11));
assert!(<Payee<Test>>::contains_key(&11));

// Reduce free_balance of controller to 0
let _ = Balances::slash(&10, Balance::max_value());

// Check the balance of the stash account has not been touched
assert_eq!(Balances::free_balance(11), 10 * 1000);
// Check these two accounts are still bonded
assert_eq!(Staking::bonded(&11), Some(10));

// Check storage items have not changed
assert!(<Ledger<Test>>::contains_key(&10));
assert!(<Bonded<Test>>::contains_key(&11));
assert!(<Validators<Test>>::contains_key(&11));
assert!(<Payee<Test>>::contains_key(&11));

// Reduce free_balance of stash to 0
let _ = Balances::slash(&11, Balance::max_value());
// Check total balance of stash
assert_eq!(Balances::total_balance(&11), 10);

// Reap the stash
assert_ok!(Staking::reap_stash(Origin::none(), 11, 0));

// Check storage items do not exist
assert!(!<Ledger<Test>>::contains_key(&10));
assert!(!<Bonded<Test>>::contains_key(&11));
assert!(!<Validators<Test>>::contains_key(&11));
assert!(!<Nominators<Test>>::contains_key(&11));
assert!(!<Payee<Test>>::contains_key(&11));
});
}

#[test]
fn on_free_balance_zero_stash_removes_nominator() {
// Tests that nominator storage items are cleaned up when stash is empty
// Tests that storage items are untouched when controller is empty
ExtBuilder::default()
.existential_deposit(10)
.balance_factor(10)
.build_and_execute(|| {
// Make 10 a nominator
assert_ok!(Staking::nominate(Origin::signed(10), vec![20]));
// Check that account 10 is a nominator
assert!(<Nominators<Test>>::contains_key(11));
// Check the balance of the nominator account
assert_eq!(Balances::free_balance(10), 10);
// Check the balance of the stash account
assert_eq!(Balances::free_balance(11), 10_000);

// Set payee information
assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Stash));

// Check storage items that should be cleaned up
assert!(<Ledger<Test>>::contains_key(&10));
assert!(<Bonded<Test>>::contains_key(&11));
assert!(<Nominators<Test>>::contains_key(&11));
assert!(<Payee<Test>>::contains_key(&11));

// Reduce free_balance of controller to 0
let _ = Balances::slash(&10, Balance::max_value());
// Check total balance of account 10
assert_eq!(Balances::total_balance(&10), 0);

// Check the balance of the stash account has not been touched
assert_eq!(Balances::free_balance(11), 10_000);
// Check these two accounts are still bonded
assert_eq!(Staking::bonded(&11), Some(10));

// Check storage items have not changed
assert!(<Ledger<Test>>::contains_key(&10));
assert!(<Bonded<Test>>::contains_key(&11));
assert!(<Nominators<Test>>::contains_key(&11));
assert!(<Payee<Test>>::contains_key(&11));
// stash is not reapable
assert_noop!(
Staking::reap_stash(Origin::signed(20), 11, 0),
Error::<Test>::FundedTarget
);
// controller or any other account is not reapable
assert_noop!(Staking::reap_stash(Origin::signed(20), 10, 0), Error::<Test>::NotStash);

// Reduce free_balance of stash to 0
let _ = Balances::slash(&11, Balance::max_value());
// Check total balance of stash
assert_eq!(Balances::total_balance(&11), 10);
// no easy way to cause an account to go below ED, we tweak their staking ledger
// instead.
Ledger::<Test>::insert(
10,
StakingLedger {
stash: 11,
total: 5,
active: 5,
unlocking: vec![],
claimed_rewards: vec![],
},
);

// Reap the stash
assert_ok!(Staking::reap_stash(Origin::none(), 11, 0));
// reap-able
assert_ok!(Staking::reap_stash(Origin::signed(20), 11, 0));

// Check storage items do not exist
// then
assert!(!<Ledger<Test>>::contains_key(&10));
assert!(!<Bonded<Test>>::contains_key(&11));
assert!(!<Validators<Test>>::contains_key(&11));
assert!(!<Nominators<Test>>::contains_key(&11));
assert!(!<Payee<Test>>::contains_key(&11));
});
}
Expand Down Expand Up @@ -2556,10 +2490,10 @@ fn garbage_collection_after_slashing() {

// reap_stash respects num_slashing_spans so that weight is accurate
assert_noop!(
Staking::reap_stash(Origin::none(), 11, 0),
Staking::reap_stash(Origin::signed(20), 11, 0),
Error::<Test>::IncorrectSlashingSpans
);
assert_ok!(Staking::reap_stash(Origin::none(), 11, 2));
assert_ok!(Staking::reap_stash(Origin::signed(20), 11, 2));

assert!(<Staking as crate::Store>::SlashingSpans::get(&11).is_none());
assert_eq!(<Staking as crate::Store>::SpanSlash::get(&(11, 0)).amount_slashed(), &0);
Expand Down

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