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Improve Staking Limits #9193

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Jun 28, 2021
Merged

Improve Staking Limits #9193

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4ad91dd
only allow `chill_other` near threshold.
shawntabrizi Jun 24, 2021
5b5375e
improve test
shawntabrizi Jun 24, 2021
9d137e8
skip limit check for existing validators / nominators
shawntabrizi Jun 24, 2021
f7c1698
add `ChillThreshold`
shawntabrizi Jun 27, 2021
4723d5a
rename to `set` for consistent api
shawntabrizi Jun 27, 2021
1778970
more tests
shawntabrizi Jun 27, 2021
0a15b45
Merge branch 'master' into shawntabrizi-improve-staking-limits
shawntabrizi Jun 27, 2021
aa5fb4e
fix some line width
shawntabrizi Jun 28, 2021
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15 changes: 11 additions & 4 deletions frame/staking/src/benchmarking.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -601,26 +601,33 @@ benchmarks! {
assert_eq!(targets.len() as u32, v);
}

update_staking_limits {
set_staking_limits {
// This function always does the same thing... just write to 4 storage items.
}: _(
RawOrigin::Root,
BalanceOf::<T>::max_value(),
BalanceOf::<T>::max_value(),
Some(u32::MAX),
Some(u32::MAX)
Some(u32::MAX),
Some(Percent::max_value())
) verify {
assert_eq!(MinNominatorBond::<T>::get(), BalanceOf::<T>::max_value());
assert_eq!(MinValidatorBond::<T>::get(), BalanceOf::<T>::max_value());
assert_eq!(MaxNominatorsCount::<T>::get(), Some(u32::MAX));
assert_eq!(MaxValidatorsCount::<T>::get(), Some(u32::MAX));
assert_eq!(ChillThreshold::<T>::get(), Some(Percent::from_percent(100)));
}

chill_other {
let (_, controller) = create_stash_controller::<T>(USER_SEED, 100, Default::default())?;
Staking::<T>::validate(RawOrigin::Signed(controller.clone()).into(), ValidatorPrefs::default())?;
Staking::<T>::update_staking_limits(
RawOrigin::Root.into(), BalanceOf::<T>::max_value(), BalanceOf::<T>::max_value(), None, None,
Staking::<T>::set_staking_limits(
RawOrigin::Root.into(),
BalanceOf::<T>::max_value(),
BalanceOf::<T>::max_value(),
Some(0),
Some(0),
Some(Percent::from_percent(0))
)?;
let caller = whitelisted_caller();
}: _(RawOrigin::Signed(caller), controller.clone())
Expand Down
80 changes: 58 additions & 22 deletions frame/staking/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1216,6 +1216,12 @@ pub mod pallet {
#[pallet::storage]
pub(crate) type StorageVersion<T: Config> = StorageValue<_, Releases, ValueQuery>;

/// The threshold for when users can start calling `chill_other` for other validators / nominators.
/// The threshold is compared to the actual number of validators / nominators (`CountFor*`) in
/// the system compared to the configured max (`Max*Count`).
#[pallet::storage]
pub(crate) type ChillThreshold<T: Config> = StorageValue<_, Percent, OptionQuery>;

#[pallet::genesis_config]
pub struct GenesisConfig<T: Config> {
pub history_depth: u32,
Expand Down Expand Up @@ -1714,16 +1720,19 @@ pub mod pallet {
pub fn validate(origin: OriginFor<T>, prefs: ValidatorPrefs) -> DispatchResult {
let controller = ensure_signed(origin)?;

// If this error is reached, we need to adjust the `MinValidatorBond` and start calling `chill_other`.
// Until then, we explicitly block new validators to protect the runtime.
if let Some(max_validators) = MaxValidatorsCount::<T>::get() {
ensure!(CounterForValidators::<T>::get() < max_validators, Error::<T>::TooManyValidators);
}

let ledger = Self::ledger(&controller).ok_or(Error::<T>::NotController)?;
ensure!(ledger.active >= MinValidatorBond::<T>::get(), Error::<T>::InsufficientBond);

let stash = &ledger.stash;

// Only check limits if they are not already a validator.
if !Validators::<T>::contains_key(stash) {
// If this error is reached, we need to adjust the `MinValidatorBond` and start calling `chill_other`.
// Until then, we explicitly block new validators to protect the runtime.
if let Some(max_validators) = MaxValidatorsCount::<T>::get() {
ensure!(CounterForValidators::<T>::get() < max_validators, Error::<T>::TooManyValidators);
}
}

Self::do_remove_nominator(stash);
Self::do_add_validator(stash, prefs);
Ok(())
Expand Down Expand Up @@ -1755,16 +1764,19 @@ pub mod pallet {
) -> DispatchResult {
let controller = ensure_signed(origin)?;

// If this error is reached, we need to adjust the `MinNominatorBond` and start calling `chill_other`.
// Until then, we explicitly block new nominators to protect the runtime.
if let Some(max_nominators) = MaxNominatorsCount::<T>::get() {
ensure!(CounterForNominators::<T>::get() < max_nominators, Error::<T>::TooManyNominators);
}

let ledger = Self::ledger(&controller).ok_or(Error::<T>::NotController)?;
ensure!(ledger.active >= MinNominatorBond::<T>::get(), Error::<T>::InsufficientBond);

let stash = &ledger.stash;

// Only check limits if they are not already a nominator.
if !Nominators::<T>::contains_key(stash) {
// If this error is reached, we need to adjust the `MinNominatorBond` and start calling `chill_other`.
// Until then, we explicitly block new nominators to protect the runtime.
if let Some(max_nominators) = MaxNominatorsCount::<T>::get() {
ensure!(CounterForNominators::<T>::get() < max_nominators, Error::<T>::TooManyNominators);
}
}

ensure!(!targets.is_empty(), Error::<T>::EmptyTargets);
ensure!(targets.len() <= T::MAX_NOMINATIONS as usize, Error::<T>::TooManyTargets);

Expand Down Expand Up @@ -2266,31 +2278,42 @@ pub mod pallet {
///
/// NOTE: Existing nominators and validators will not be affected by this update.
/// to kick people under the new limits, `chill_other` should be called.
#[pallet::weight(T::WeightInfo::update_staking_limits())]
pub fn update_staking_limits(
#[pallet::weight(T::WeightInfo::set_staking_limits())]
pub fn set_staking_limits(
origin: OriginFor<T>,
min_nominator_bond: BalanceOf<T>,
min_validator_bond: BalanceOf<T>,
max_nominator_count: Option<u32>,
max_validator_count: Option<u32>,
threshold: Option<Percent>,
) -> DispatchResult {
ensure_root(origin)?;
MinNominatorBond::<T>::set(min_nominator_bond);
MinValidatorBond::<T>::set(min_validator_bond);
MaxNominatorsCount::<T>::set(max_nominator_count);
MaxValidatorsCount::<T>::set(max_validator_count);
ChillThreshold::<T>::set(threshold);
Ok(())
}

/// Declare a `controller` as having no desire to either validator or nominate.
/// Declare a `controller` to stop participating as either a validator or nominator.
///
/// Effects will be felt at the beginning of the next era.
///
/// The dispatch origin for this call must be _Signed_, but can be called by anyone.
///
/// If the caller is the same as the controller being targeted, then no further checks
/// are enforced. However, this call can also be made by an third party user who witnesses
/// that this controller does not satisfy the minimum bond requirements to be in their role.
/// If the caller is the same as the controller being targeted, then no further checks are
/// enforced, and this function behaves just like `chill`.
///
/// If the caller is different than the controller being targeted, the following conditions
/// must be met:
/// * A `ChillThreshold` must be set and checked which defines how close to the max
/// nominators or validators we must reach before users can start chilling one-another.
/// * A `MaxNominatorCount` and `MaxValidatorCount` must be set which is used to determine
/// how close we are to the threshold.
/// * A `MinNominatorBond` and `MinValidatorBond` must be set and checked, which determines
/// if this is a person that should be chilled because they have not met the threshold
/// bond required.
///
/// This can be helpful if bond requirements are updated, and we need to remove old users
/// who do not satisfy these requirements.
Expand All @@ -2307,14 +2330,27 @@ pub mod pallet {
let ledger = Self::ledger(&controller).ok_or(Error::<T>::NotController)?;
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@emostov emostov Jun 25, 2021 •
edited
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Should the origin param for chill_other be configurable for the pallet? (I believe @shawntabrizi mentioned this idea already somewhere)

The current, permission nature of this call is useful for scenarios where we want a network to be continuously "self adjusting". But I think we can imagine scenarios where this makes more sense as a governance only call (that then can be turned into a permission-less call with a runtime upgrade).

While I don't see how it would improve security properties, I think having a call like this go through governance could benefit the community

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@emostov emostov Jun 25, 2021

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Tagential, is it possible to make a call origin configurable without a runtime upgrade?

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@kianenigma kianenigma Jun 27, 2021

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Tagential, is it possible to make a call origin configurable without a runtime upgrade?

Nope, that's logic change and needs altering :code.

let stash = ledger.stash;

// If the caller is not the controller, we want to check that the minimum bond
// requirements are not satisfied, and thus we have reason to chill this user.
// In order for one user to chill another user, the following conditions must be met:
// * A `ChillThreshold` is set which defines how close to the max nominators or
// validators we must reach before users can start chilling one-another.
// * A `MaxNominatorCount` and `MaxValidatorCount` which is used to determine how close
// we are to the threshold.
// * A `MinNominatorBond` and `MinValidatorBond` which is the final condition checked to
// determine this is a person that should be chilled because they have not met the
// threshold bond required.
//
// Otherwise, if caller is the same as the controller, this is just like `chill`.
if caller != controller {
let threshold = ChillThreshold::<T>::get().ok_or(Error::<T>::CannotChillOther)?;
let min_active_bond = if Nominators::<T>::contains_key(&stash) {
let max_nominator_count = MaxNominatorsCount::<T>::get().ok_or(Error::<T>::CannotChillOther)?;
let current_nominator_count = CounterForNominators::<T>::get();
ensure!(threshold * max_nominator_count < current_nominator_count, Error::<T>::CannotChillOther);
MinNominatorBond::<T>::get()
} else if Validators::<T>::contains_key(&stash) {
let max_validator_count = MaxValidatorsCount::<T>::get().ok_or(Error::<T>::CannotChillOther)?;
let current_validator_count = CounterForValidators::<T>::get();
ensure!(threshold * max_validator_count < current_validator_count, Error::<T>::CannotChillOther);
MinValidatorBond::<T>::get()
} else {
Zero::zero()
Expand Down
121 changes: 100 additions & 21 deletions frame/staking/src/tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4050,12 +4050,18 @@ mod election_data_provider {
// 500 is not enough for any role
assert_ok!(Staking::bond(Origin::signed(3), 4, 500, RewardDestination::Controller));
assert_noop!(Staking::nominate(Origin::signed(4), vec![1]), Error::<Test>::InsufficientBond);
assert_noop!(Staking::validate(Origin::signed(4), ValidatorPrefs::default()), Error::<Test>::InsufficientBond);
assert_noop!(
Staking::validate(Origin::signed(4), ValidatorPrefs::default()),
Error::<Test>::InsufficientBond,
);

// 1000 is enough for nominator
assert_ok!(Staking::bond_extra(Origin::signed(3), 500));
assert_ok!(Staking::nominate(Origin::signed(4), vec![1]));
assert_noop!(Staking::validate(Origin::signed(4), ValidatorPrefs::default()), Error::<Test>::InsufficientBond);
assert_noop!(
Staking::validate(Origin::signed(4), ValidatorPrefs::default()),
Error::<Test>::InsufficientBond,
);

// 1500 is enough for validator
assert_ok!(Staking::bond_extra(Origin::signed(3), 500));
Expand Down Expand Up @@ -4083,24 +4089,80 @@ mod election_data_provider {
.min_nominator_bond(1_000)
.min_validator_bond(1_500)
.build_and_execute(|| {
// Nominator
assert_ok!(Staking::bond(Origin::signed(1), 2, 1000, RewardDestination::Controller));
assert_ok!(Staking::nominate(Origin::signed(2), vec![1]));
for i in 0 .. 15 {
let a = 4 * i;
let b = 4 * i + 1;
let c = 4 * i + 2;
let d = 4 * i + 3;
Balances::make_free_balance_be(&a, 100_000);
Balances::make_free_balance_be(&b, 100_000);
Balances::make_free_balance_be(&c, 100_000);
Balances::make_free_balance_be(&d, 100_000);

// Nominator
assert_ok!(Staking::bond(Origin::signed(a), b, 1000, RewardDestination::Controller));
assert_ok!(Staking::nominate(Origin::signed(b), vec![1]));

// Validator
assert_ok!(Staking::bond(Origin::signed(c), d, 1500, RewardDestination::Controller));
assert_ok!(Staking::validate(Origin::signed(d), ValidatorPrefs::default()));
}

// Validator
assert_ok!(Staking::bond(Origin::signed(3), 4, 1500, RewardDestination::Controller));
assert_ok!(Staking::validate(Origin::signed(4), ValidatorPrefs::default()));
// To chill other users, we need to:
// * Set a minimum bond amount
// * Set a limit
// * Set a threshold
//
// If any of these are missing, we do not have enough information to allow the
// `chill_other` to succeed from one user to another.

// Can't chill these users
assert_noop!(Staking::chill_other(Origin::signed(1), 2), Error::<Test>::CannotChillOther);
assert_noop!(Staking::chill_other(Origin::signed(1), 4), Error::<Test>::CannotChillOther);

// Change the minimum bond
assert_ok!(Staking::update_staking_limits(Origin::root(), 1_500, 2_000, None, None));
assert_noop!(Staking::chill_other(Origin::signed(1337), 1), Error::<Test>::CannotChillOther);
assert_noop!(Staking::chill_other(Origin::signed(1337), 3), Error::<Test>::CannotChillOther);

// Change the minimum bond... but no limits.
assert_ok!(Staking::set_staking_limits(Origin::root(), 1_500, 2_000, None, None, None));

// Still can't chill these users
assert_noop!(Staking::chill_other(Origin::signed(1337), 1), Error::<Test>::CannotChillOther);
assert_noop!(Staking::chill_other(Origin::signed(1337), 3), Error::<Test>::CannotChillOther);

// Add limits, but no threshold
assert_ok!(Staking::set_staking_limits(Origin::root(), 1_500, 2_000, Some(10), Some(10), None));

// Still can't chill these users
assert_noop!(Staking::chill_other(Origin::signed(1337), 1), Error::<Test>::CannotChillOther);
assert_noop!(Staking::chill_other(Origin::signed(1337), 3), Error::<Test>::CannotChillOther);

// Add threshold, but no limits
assert_ok!(Staking::set_staking_limits(
Origin::root(), 1_500, 2_000, None, None, Some(Percent::from_percent(0))
));

// Still can't chill these users
assert_noop!(Staking::chill_other(Origin::signed(1337), 1), Error::<Test>::CannotChillOther);
assert_noop!(Staking::chill_other(Origin::signed(1337), 3), Error::<Test>::CannotChillOther);

// Add threshold and limits
assert_ok!(Staking::set_staking_limits(
Origin::root(), 1_500, 2_000, Some(10), Some(10), Some(Percent::from_percent(75))
));

// 16 people total because tests start with 1 active one
assert_eq!(CounterForNominators::<Test>::get(), 16);
assert_eq!(CounterForValidators::<Test>::get(), 16);

// Users can now be chilled down to 7 people, so we try to remove 9 of them (starting with 16)
for i in 6 .. 15 {
let b = 4 * i + 1;
let d = 4 * i + 3;
assert_ok!(Staking::chill_other(Origin::signed(1337), b));
assert_ok!(Staking::chill_other(Origin::signed(1337), d));
}

// Users can now be chilled
assert_ok!(Staking::chill_other(Origin::signed(1), 2));
assert_ok!(Staking::chill_other(Origin::signed(1), 4));
// Cant go lower.
assert_noop!(Staking::chill_other(Origin::signed(1337), 1), Error::<Test>::CannotChillOther);
assert_noop!(Staking::chill_other(Origin::signed(1337), 3), Error::<Test>::CannotChillOther);
})
}

Expand All @@ -4114,36 +4176,53 @@ mod election_data_provider {

// Change the maximums
let max = 10;
assert_ok!(Staking::update_staking_limits(Origin::root(), 10, 10, Some(max), Some(max)));
assert_ok!(Staking::set_staking_limits(
Origin::root(), 10, 10, Some(max), Some(max), Some(Percent::from_percent(0))
));

// can create `max - validator_count` validators
assert_ok!(testing_utils::create_validators::<Test>(max - validator_count, 100));
let mut some_existing_validator = AccountId::default();
for i in 0 .. max - validator_count {
let (_, controller) = testing_utils::create_stash_controller::<Test>(
i + 10_000_000, 100, RewardDestination::Controller,
).unwrap();
assert_ok!(Staking::validate(Origin::signed(controller), ValidatorPrefs::default()));
some_existing_validator = controller;
}

// but no more
let (_, last_validator) = testing_utils::create_stash_controller::<Test>(
1337, 100, RewardDestination::Controller,
).unwrap();

assert_noop!(
Staking::validate(Origin::signed(last_validator), ValidatorPrefs::default()),
Error::<Test>::TooManyValidators,
);

// same with nominators
let mut some_existing_nominator = AccountId::default();
for i in 0 .. max - nominator_count {
let (_, controller) = testing_utils::create_stash_controller::<Test>(
i + 10_000_000, 100, RewardDestination::Controller,
i + 20_000_000, 100, RewardDestination::Controller,
).unwrap();
assert_ok!(Staking::nominate(Origin::signed(controller), vec![1]));
some_existing_nominator = controller;
}

// one more is too many
let (_, last_nominator) = testing_utils::create_stash_controller::<Test>(
20_000_000, 100, RewardDestination::Controller,
30_000_000, 100, RewardDestination::Controller,
).unwrap();
assert_noop!(Staking::nominate(Origin::signed(last_nominator), vec![1]), Error::<Test>::TooManyNominators);

// Re-nominate works fine
assert_ok!(Staking::nominate(Origin::signed(some_existing_nominator), vec![1]));
// Re-validate works fine
assert_ok!(Staking::validate(Origin::signed(some_existing_validator), ValidatorPrefs::default()));

// No problem when we set to `None` again
assert_ok!(Staking::update_staking_limits(Origin::root(), 10, 10, None, None));
assert_ok!(Staking::set_staking_limits(Origin::root(), 10, 10, None, None, None));
assert_ok!(Staking::nominate(Origin::signed(last_nominator), vec![1]));
assert_ok!(Staking::validate(Origin::signed(last_validator), ValidatorPrefs::default()));
})
Expand Down
6 changes: 3 additions & 3 deletions frame/staking/src/weights.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -70,7 +70,7 @@ pub trait WeightInfo {
fn new_era(v: u32, n: u32, ) -> Weight;
fn get_npos_voters(v: u32, n: u32, s: u32, ) -> Weight;
fn get_npos_targets(v: u32, ) -> Weight;
fn update_staking_limits() -> Weight;
fn set_staking_limits() -> Weight;
fn chill_other() -> Weight;
}

Expand Down Expand Up @@ -252,7 +252,7 @@ impl<T: frame_system::Config> WeightInfo for SubstrateWeight<T> {
.saturating_add(T::DbWeight::get().reads(1 as Weight))
.saturating_add(T::DbWeight::get().reads((1 as Weight).saturating_mul(v as Weight)))
}
fn update_staking_limits() -> Weight {
fn set_staking_limits() -> Weight {
(5_028_000 as Weight)
.saturating_add(T::DbWeight::get().writes(4 as Weight))
}
Expand Down Expand Up @@ -440,7 +440,7 @@ impl WeightInfo for () {
.saturating_add(RocksDbWeight::get().reads(1 as Weight))
.saturating_add(RocksDbWeight::get().reads((1 as Weight).saturating_mul(v as Weight)))
}
fn update_staking_limits() -> Weight {
fn set_staking_limits() -> Weight {
(5_028_000 as Weight)
.saturating_add(RocksDbWeight::get().writes(4 as Weight))
}
Expand Down