Delegated staking

substrate/runtime/staking/src/lib.rs

@@ -135,7 +135,9 @@ decl_module! {
 	pub enum Call where aux: T::PublicAux {
 		fn transfer(aux, dest: RawAddress<T::AccountId, T::AccountIndex>, value: T::Balance) -> Result = 0;
 		fn stake(aux) -> Result = 1;
-		fn unstake(aux) -> Result = 2;
+		fn unstake(aux, index: u32) -> Result = 2;
+		fn nominate(aux, target: RawAddress<T::AccountId, T::AccountIndex>) -> Result = 3;
+		fn unnominate(aux, target_index: u32) -> Result = 4;
 	}
 
 	#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
@@ -157,6 +159,7 @@ decl_storage! {
 	// The length of a staking era in sessions.
 	pub SessionsPerEra get(sessions_per_era): b"sta:spe" => required T::BlockNumber;
 	// The total amount of stake on the system.
+	// TODO: this doesn't actually track total stake yet - it should do.
 	pub TotalStake get(total_stake): b"sta:tot" => required T::Balance;
 	// The fee to be paid for making a transaction; the base.
 	pub TransactionBaseFee get(transaction_base_fee): b"sta:basefee" => required T::Balance;
@@ -172,7 +175,6 @@ decl_storage! {
 	pub CreationFee get(creation_fee): b"sta:creation_fee" => required T::Balance;
 	// The fee required to create a contract. At least as big as ReclaimRebate.
 	pub ContractFee get(contract_fee): b"sta:contract_fee" => required T::Balance;
-
 	// Maximum reward, per validator, that is provided per acceptable session.
 	pub SessionReward get(session_reward): b"sta:session_reward" => required T::Balance;
 	// Slash, per validator that is taken per abnormal era end.
@@ -181,11 +183,19 @@ decl_storage! {
 	// The current era index.
 	pub CurrentEra get(current_era): b"sta:era" => required T::BlockNumber;
 	// All the accounts with a desire to stake.
-	pub Intentions: b"sta:wil:" => default Vec<T::AccountId>;
+	pub Intentions get(intentions): b"sta:wil:" => default Vec<T::AccountId>;
+	// All nominator -> nominee relationships.
+	pub Nominating get(nominating): b"sta:nominating" => map [ T::AccountId => T::AccountId ];
+	// Nominators for a particular account.
+	pub NominatorsFor get(nominators_for): b"sta:nominators_for" => default map [ T::AccountId => Vec<T::AccountId> ];
+	// Nominators for a particular account that is in action right now.
+	pub CurrentNominatorsFor get(current_nominators_for): b"sta:current_nominators_for" => default map [ T::AccountId => Vec<T::AccountId> ];
 	// The next value of sessions per era.
 	pub NextSessionsPerEra get(next_sessions_per_era): b"sta:nse" => T::BlockNumber;
 	// The session index at which the era length last changed.
 	pub LastEraLengthChange get(last_era_length_change): b"sta:lec" => default T::BlockNumber;
+	// The current era stake threshold
+	pub StakeThreshold get(stake_threshold): b"sta:stake_threshold" => required T::Balance;
 
 	// The next free enumeration set.
 	pub NextEnumSet get(next_enum_set): b"sta:next_enum" => required T::AccountIndex;
@@ -305,27 +315,82 @@ impl<T: Trait> Module<T> {
 	///
 	/// Effects will be felt at the beginning of the next era.
 	fn stake(aux: &T::PublicAux) -> Result {
+		let aux = aux.ref_into();
+		ensure!(Self::nominating(aux).is_none(), "Cannot stake if already nominating.");
 		let mut intentions = <Intentions<T>>::get();
 		// can't be in the list twice.
-		ensure!(intentions.iter().find(|&t| t == aux.ref_into()).is_none(), "Cannot stake if already staked.");
-		intentions.push(aux.ref_into().clone());
+		ensure!(intentions.iter().find(|&t| t == aux).is_none(), "Cannot stake if already staked.");
+		intentions.push(aux.clone());
 		<Intentions<T>>::put(intentions);
-		<Bondage<T>>::insert(aux.ref_into(), T::BlockNumber::max_value());
+		<Bondage<T>>::insert(aux, T::BlockNumber::max_value());
 		Ok(())
 	}
 
 	/// Retract the desire to stake for the transactor.
 	///
 	/// Effects will be felt at the beginning of the next era.
-	fn unstake(aux: &T::PublicAux) -> Result {
+	fn unstake(aux: &T::PublicAux, position: u32) -> Result {
+		let aux = aux.ref_into();
+		let position = position as usize;
 		let mut intentions = <Intentions<T>>::get();
-		let position = intentions.iter().position(|t| t == aux.ref_into()).ok_or("Cannot unstake if not already staked.")?;
+//		let position = intentions.iter().position(|t| t == aux.ref_into()).ok_or("Cannot unstake if not already staked.")?;
+		if intentions.get(position) != Some(aux) {
+			return Err("Invalid index")
+		}
 		intentions.swap_remove(position);
 		<Intentions<T>>::put(intentions);
 		<Bondage<T>>::insert(aux.ref_into(), Self::current_era() + Self::bonding_duration());
 		Ok(())
 	}
 
+	fn nominate(aux: &T::PublicAux, target: RawAddress<T::AccountId, T::AccountIndex>) -> Result {
+		let target = Self::lookup(target)?;
+		let aux = aux.ref_into();
+
+		ensure!(Self::nominating(aux).is_none(), "Cannot nominate if already nominating.");
+		ensure!(Self::intentions().iter().find(|&t| t == aux.ref_into()).is_none(), "Cannot nominate if already staked.");
+
+		// update nominators_for
+		let mut t = Self::nominators_for(&target);
+		t.push(aux.clone());
+		<NominatorsFor<T>>::insert(&target, t);
+
+		// update nominating
+		<Nominating<T>>::insert(aux, &target);
+
+		// Update bondage
+		<Bondage<T>>::insert(aux.ref_into(), T::BlockNumber::max_value());
+
+		Ok(())
+	}
+
+	/// Will panic if called when source isn't currently nominating target.
+	/// Updates Nominating, NominatorsFor and NominationBalance.
+	fn unnominate(aux: &T::PublicAux, target_index: u32) -> Result {
+		let source = aux.ref_into();
+		let target_index = target_index as usize;
+
+		let target = <Nominating<T>>::get(source).ok_or("Account must be nominating")?;
+
+		let mut t = Self::nominators_for(&target);
+		if t.get(target_index) != Some(source) {
+			return Err("Invalid target index")
+		}
+
+		// Ok - all valid.
+
+		// update nominators_for
+		t.swap_remove(target_index);
+		<NominatorsFor<T>>::insert(&target, t);
+
+		// update nominating
+		<Nominating<T>>::remove(source);
+
+		// update bondage
+		<Bondage<T>>::insert(aux.ref_into(), Self::current_era() + Self::bonding_duration());
+		Ok(())
+	}
+
 	// PRIV DISPATCH
 
 	/// Set the number of sessions in an era.
@@ -496,20 +561,42 @@ impl<T: Trait> Module<T> {
 			let reward = Self::session_reward() * T::Balance::sa(percent) / T::Balance::sa(65536usize);
 			// apply good session reward
 			for v in <session::Module<T>>::validators().iter() {
-				let _ = Self::reward(v, reward);	// will never fail as validator accounts must be created, but even if it did, it's just a missed reward.
+				let noms = Self::current_nominators_for(v);
+				let total = noms.iter().map(Self::voting_balance).fold(Self::voting_balance(v), |acc, x| acc + x);
+				if !total.is_zero() {
+					let safe_mul_rational = |b| b * reward / total;// TODO: avoid overflow
+					for n in noms.iter() {
+						let _ = Self::reward(n, safe_mul_rational(Self::voting_balance(n)));
+					}
+					let _ = Self::reward(v, safe_mul_rational(Self::voting_balance(v)));
+				}
 			}
 		} else {
 			// slash
 			let early_era_slash = Self::early_era_slash();
 			for v in <session::Module<T>>::validators().iter() {
-				Self::slash(v, early_era_slash);
+				if let Some(rem) = Self::slash(v, early_era_slash) {
+					let noms = Self::current_nominators_for(v);
+					let total = noms.iter().map(Self::voting_balance).fold(Zero::zero(), |acc, x| acc + x);
+					for n in noms.iter() {
+						//let r = Self::voting_balance(n) * reward / total;	// correct formula, but might overflow with large slash * total.
+						let quant = T::Balance::sa(1usize << 31);
+						let s = (Self::voting_balance(n) * quant / total) * rem / quant; // avoid overflow by using quant as a denominator.
+						let _ = Self::slash(n, s);	// best effort - not much that can be done on fail.
+					}
+				}
 			}
 		}
 		if ((session_index - Self::last_era_length_change()) % Self::sessions_per_era()).is_zero() || !normal_rotation {
 			Self::new_era();
 		}
 	}
 
+	/// Balance of a (potential) validator that includes all nominators.
+	fn nomination_balance(who: &T::AccountId) -> T::Balance {
+		Self::nominators_for(who).iter().map(Self::voting_balance).fold(Zero::zero(), |acc, x| acc + x)
+	}
+
 	/// The era has changed - enact new staking set.
 	///
 	/// NOTE: This always happens immediately before a session change to ensure that new validators
@@ -530,17 +617,30 @@ impl<T: Trait> Module<T> {
 		// combination of validators, then use session::internal::set_validators().
 		// for now, this just orders would-be stakers by their balances and chooses the top-most
 		// <ValidatorCount<T>>::get() of them.
+		// TODO: this is not sound. this should be moved to an off-chain solution mechanism.
 		let mut intentions = <Intentions<T>>::get()
 			.into_iter()
-			.map(|v| (Self::voting_balance(&v), v))
+			.map(|v| (Self::voting_balance(&v) + Self::nomination_balance(&v), v))
 			.collect::<Vec<_>>();
 		intentions.sort_unstable_by(|&(ref b1, _), &(ref b2, _)| b2.cmp(&b1));
-		<session::Module<T>>::set_validators(
-			&intentions.into_iter()
+
+		<StakeThreshold<T>>::put(
+			if intentions.len() > 0 {
+				let i = (<ValidatorCount<T>>::get() as usize).min(intentions.len() - 1);
+				intentions[i].0.clone()
+			} else { Zero::zero() }
+		);
+		let vals = &intentions.into_iter()
 				.map(|(_, v)| v)
 				.take(<ValidatorCount<T>>::get() as usize)
-				.collect::<Vec<_>>()
-		);
+				.collect::<Vec<_>>();
+		for v in <session::Module<T>>::validators().iter() {
+			<CurrentNominatorsFor<T>>::remove(v);
+		}
+		for v in vals.iter() {
+			<CurrentNominatorsFor<T>>::insert(v, Self::nominators_for(v));
+		}
+		<session::Module<T>>::set_validators(vals);
 	}
 
 	fn enum_set_size() -> T::AccountIndex {

substrate/runtime/staking/src/mock.rs

@@ -98,7 +98,7 @@ pub fn new_test_ext(ext_deposit: u64, session_length: u64, sessions_per_era: u64
 		contract_fee: 0,
 		reclaim_rebate: 0,
 		session_reward: reward,
-		early_era_slash: if monied { 10 } else { 0 },
+		early_era_slash: if monied { 20 } else { 0 },
 	}.build_storage());
 	t.extend(timestamp::GenesisConfig::<Test>{
 		period: 5

substrate/runtime/staking/src/tests.rs

@@ -79,11 +79,18 @@ fn slashing_should_work() {
 		assert_eq!(Session::current_index(), 1);
 		assert_eq!(Staking::voting_balance(&10), 11);
 
-		System::set_block_number(4);
+		System::set_block_number(6);
+		Timestamp::set_timestamp(30);	// on time.
+		Session::check_rotate_session();
+		assert_eq!(Staking::current_era(), 0);
+		assert_eq!(Session::current_index(), 2);
+		assert_eq!(Staking::voting_balance(&10), 21);
+
+		System::set_block_number(7);
 		Timestamp::set_timestamp(100);	// way too late - early exit.
 		Session::check_rotate_session();
 		assert_eq!(Staking::current_era(), 1);
-		assert_eq!(Session::current_index(), 2);
+		assert_eq!(Session::current_index(), 3);
 		assert_eq!(Staking::voting_balance(&10), 1);
 	});
 }
@@ -192,7 +199,7 @@ fn staking_should_work() {
 		// Block 3: Unstake highest, introduce another staker. No change yet.
 		System::set_block_number(3);
 		assert_ok!(Staking::stake(&3));
-		assert_ok!(Staking::unstake(&4));
+		assert_ok!(Staking::unstake(&4, Staking::intentions().iter().position(|&x| x == 4).unwrap() as u32));
 		assert_eq!(Staking::current_era(), 1);
 		Session::check_rotate_session();
 
@@ -214,7 +221,7 @@ fn staking_should_work() {
 
 		// Block 7: Unstake three. No change yet.
 		System::set_block_number(7);
-		assert_ok!(Staking::unstake(&3));
+		assert_ok!(Staking::unstake(&3, Staking::intentions().iter().position(|&x| x == 3).unwrap() as u32));
 		Session::check_rotate_session();
 		assert_eq!(Session::validators(), vec![1, 3]);
 
@@ -225,6 +232,110 @@ fn staking_should_work() {
 	});
 }
 
+#[test]
+fn nominating_and_rewards_should_work() {
+	with_externalities(&mut new_test_ext(0, 1, 1, 0, true, 10), || {
+		assert_eq!(Staking::era_length(), 1);
+		assert_eq!(Staking::validator_count(), 2);
+		assert_eq!(Staking::bonding_duration(), 3);
+		assert_eq!(Session::validators(), vec![10, 20]);
+
+		System::set_block_number(1);
+		assert_ok!(Staking::stake(&1));
+		assert_ok!(Staking::stake(&2));
+		assert_ok!(Staking::stake(&3));
+		assert_ok!(Staking::nominate(&4, 1.into()));
+		Session::check_rotate_session();
+		assert_eq!(Staking::current_era(), 1);
+		assert_eq!(Session::validators(), vec![1, 3]);	// 4 + 1, 3
+		assert_eq!(Staking::voting_balance(&1), 10);
+		assert_eq!(Staking::voting_balance(&2), 20);
+		assert_eq!(Staking::voting_balance(&3), 30);
+		assert_eq!(Staking::voting_balance(&4), 40);
+
+		System::set_block_number(2);
+		assert_ok!(Staking::unnominate(&4, 0));
+		Session::check_rotate_session();
+		assert_eq!(Staking::current_era(), 2);
+		assert_eq!(Session::validators(), vec![3, 2]);
+		assert_eq!(Staking::voting_balance(&1), 12);
+		assert_eq!(Staking::voting_balance(&2), 20);
+		assert_eq!(Staking::voting_balance(&3), 40);
+		assert_eq!(Staking::voting_balance(&4), 48);
+
+		System::set_block_number(3);
+		assert_ok!(Staking::stake(&4));
+		assert_ok!(Staking::unstake(&3, Staking::intentions().iter().position(|&x| x == 3).unwrap() as u32));
+		assert_ok!(Staking::nominate(&3, 1.into()));
+		Session::check_rotate_session();
+		assert_eq!(Session::validators(), vec![1, 4]);
+		assert_eq!(Staking::voting_balance(&1), 12);
+		assert_eq!(Staking::voting_balance(&2), 30);
+		assert_eq!(Staking::voting_balance(&3), 50);
+		assert_eq!(Staking::voting_balance(&4), 48);
+
+		System::set_block_number(4);
+		Session::check_rotate_session();
+		assert_eq!(Staking::voting_balance(&1), 13);
+		assert_eq!(Staking::voting_balance(&2), 30);
+		assert_eq!(Staking::voting_balance(&3), 58);
+		assert_eq!(Staking::voting_balance(&4), 58);
+	});
+}
+
+#[test]
+fn nominating_slashes_should_work() {
+	with_externalities(&mut new_test_ext(0, 2, 2, 0, true, 10), || {
+		assert_eq!(Staking::era_length(), 4);
+		assert_eq!(Staking::validator_count(), 2);
+		assert_eq!(Staking::bonding_duration(), 3);
+		assert_eq!(Session::validators(), vec![10, 20]);
+
+		System::set_block_number(2);
+		Session::check_rotate_session();
+
+		Timestamp::set_timestamp(15);
+		System::set_block_number(4);
+		assert_ok!(Staking::stake(&1));
+		assert_ok!(Staking::stake(&3));
+		assert_ok!(Staking::nominate(&2, 3.into()));
+		assert_ok!(Staking::nominate(&4, 1.into()));
+		Session::check_rotate_session();
+
+		assert_eq!(Staking::current_era(), 1);
+		assert_eq!(Session::validators(), vec![1, 3]);	// 1 + 4, 3 + 2
+		assert_eq!(Staking::voting_balance(&1), 10);
+		assert_eq!(Staking::voting_balance(&2), 20);
+		assert_eq!(Staking::voting_balance(&3), 30);
+		assert_eq!(Staking::voting_balance(&4), 40);
+
+		System::set_block_number(5);
+		Timestamp::set_timestamp(100);	// late
+		assert_eq!(Session::blocks_remaining(), 1);
+		assert!(Session::broken_validation());
+		Session::check_rotate_session();
+
+		assert_eq!(Staking::current_era(), 2);
+		assert_eq!(Staking::voting_balance(&1), 0);
+		assert_eq!(Staking::voting_balance(&2), 20);
+		assert_eq!(Staking::voting_balance(&3), 10);
+		assert_eq!(Staking::voting_balance(&4), 30);
+	});
+}
+
+#[test]
+fn double_staking_should_fail() {
+	with_externalities(&mut new_test_ext(0, 1, 2, 0, true, 0), || {
+		System::set_block_number(1);
+		assert_ok!(Staking::stake(&1));
+		assert_noop!(Staking::stake(&1), "Cannot stake if already staked.");
+		assert_noop!(Staking::nominate(&1, 1.into()), "Cannot nominate if already staked.");
+		assert_ok!(Staking::nominate(&2, 1.into()));
+		assert_noop!(Staking::stake(&2), "Cannot stake if already nominating.");
+		assert_noop!(Staking::nominate(&2, 1.into()), "Cannot nominate if already nominating.");
+	});
+}
+
 #[test]
 fn staking_eras_work() {
 	with_externalities(&mut new_test_ext(0, 1, 2, 0, true, 0), || {