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add rewards math (#3673)

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* add rewards math

* fixup
This commit is contained in:
Rob Walker
2019-04-07 21:45:28 -07:00
committed by GitHub
parent 72b7419e1c
commit 79bf3cf70d
3 changed files with 155 additions and 31 deletions
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3
programs/stake_api/src/stake_instruction.rs
View File

@ -91,7 +91,8 @@ pub fn process_instruction(
}
let (stake, vote) = rest.split_at_mut(1);
let stake = &mut stake[0];
let vote = &vote[0];
let vote = &mut vote[0];
me.redeem_vote_credits(stake, vote)
}
}

163
programs/stake_api/src/stake_state.rs
View File

@ -29,13 +29,56 @@ impl Default for StakeState {
}
}
}
// TODO: trusted values of network parameters come from where?
const TICKS_PER_SECOND: f64 = 10f64;
const TICKS_PER_SLOT: f64 = 8f64;
// credits/yr or slots/yr is seconds/year * ticks/second * slots/tick
const CREDITS_PER_YEAR: f64 = (365f64 * 24f64 * 3600f64) * TICKS_PER_SECOND / TICKS_PER_SLOT;
// TODO: 20% is a niiice rate... TODO: make this a member of MiningPool?
const STAKE_REWARD_TARGET_RATE: f64 = 0.20;
#[cfg(test)]
const STAKE_GETS_PAID_EVERY_VOTE: u64 = 200_000_000; // if numbers above move, fix this
impl StakeState {
pub fn calculate_rewards(
credits_observed: u64,
stake: u64,
vote_state: &VoteState,
) -> Option<(u64, u64)> {
if credits_observed >= vote_state.credits() {
return None;
}
let total_rewards = stake as f64
* STAKE_REWARD_TARGET_RATE
* (vote_state.credits() - credits_observed) as f64
/ CREDITS_PER_YEAR;
// don't bother trying to collect fractional lamports
if total_rewards < 1f64 {
return None;
}
let (voter_rewards, staker_rewards, is_split) = vote_state.commission_split(total_rewards);
if (voter_rewards < 1f64 || staker_rewards < 1f64) && is_split {
// don't bother trying to collect fractional lamports
return None;
}
Some((voter_rewards as u64, staker_rewards as u64))
}
}
pub trait StakeAccount {
fn delegate_stake(&mut self, vote_account: &KeyedAccount) -> Result<(), InstructionError>;
fn redeem_vote_credits(
&mut self,
stake_account: &mut KeyedAccount,
vote_account: &KeyedAccount,
vote_account: &mut KeyedAccount,
) -> Result<(), InstructionError>;
}
@ -59,13 +102,13 @@ impl<'a> StakeAccount for KeyedAccount<'a> {
fn redeem_vote_credits(
&mut self,
stake_account: &mut KeyedAccount,
vote_account: &KeyedAccount,
vote_account: &mut KeyedAccount,
) -> Result<(), InstructionError> {
if let (
StakeState::MiningPool,
StakeState::Delegate {
voter_id,
mut credits_observed,
credits_observed,
},
) = (self.state()?, stake_account.state()?)
{
@ -79,23 +122,26 @@ impl<'a> StakeAccount for KeyedAccount<'a> {
return Err(InstructionError::InvalidAccountData);
}
let credits = vote_state.credits() - credits_observed;
credits_observed = vote_state.credits();
if self.account.lamports < credits {
return Err(InstructionError::UnbalancedInstruction);
}
// TODO: commission and network inflation parameter
// mining pool lamports reduced by credits * network_inflation_param
// stake_account and vote_account lamports up by the net
// split by a commission in vote_state
self.account.lamports -= credits;
stake_account.account.lamports += credits;
stake_account.set_state(&StakeState::Delegate {
voter_id,
if let Some((stakers_reward, voters_reward)) = StakeState::calculate_rewards(
credits_observed,
})
stake_account.account.lamports,
&vote_state,
) {
if self.account.lamports < (stakers_reward + voters_reward) {
return Err(InstructionError::UnbalancedInstruction);
}
self.account.lamports -= stakers_reward + voters_reward;
stake_account.account.lamports += stakers_reward;
vote_account.account.lamports += voters_reward;
stake_account.set_state(&StakeState::Delegate {
voter_id,
credits_observed: vote_state.credits(),
})
} else {
// not worth collecting
Ok(())
}
} else {
Err(InstructionError::InvalidAccountData)
}
@ -153,6 +199,53 @@ mod tests {
.delegate_stake(&vote_keyed_account)
.is_err());
}
#[test]
fn test_stake_state_calculate_rewards() {
let mut vote_state = VoteState::default();
let mut vote_i = 0;
// put a credit in the vote_state
while vote_state.credits() == 0 {
vote_state.process_vote(Vote::new(vote_i));
vote_i += 1;
}
// this guy can't collect now, not enough stake to get paid on 1 credit
assert_eq!(None, StakeState::calculate_rewards(0, 100, &vote_state));
// this guy can
assert_eq!(
Some((0, 1)),
StakeState::calculate_rewards(0, STAKE_GETS_PAID_EVERY_VOTE, &vote_state)
);
// but, there's not enough to split
vote_state.commission = std::u32::MAX / 2;
assert_eq!(
None,
StakeState::calculate_rewards(0, STAKE_GETS_PAID_EVERY_VOTE, &vote_state)
);
// put more credit in the vote_state
while vote_state.credits() < 10 {
vote_state.process_vote(Vote::new(vote_i));
vote_i += 1;
}
vote_state.commission = 0;
assert_eq!(
Some((0, 10)),
StakeState::calculate_rewards(0, STAKE_GETS_PAID_EVERY_VOTE, &vote_state)
);
vote_state.commission = std::u32::MAX;
assert_eq!(
Some((10, 0)),
StakeState::calculate_rewards(0, STAKE_GETS_PAID_EVERY_VOTE, &vote_state)
);
vote_state.commission = std::u32::MAX / 2;
assert_eq!(
Some((5, 5)),
StakeState::calculate_rewards(0, STAKE_GETS_PAID_EVERY_VOTE, &vote_state)
);
// not even enough stake to get paid on 10 credits...
assert_eq!(None, StakeState::calculate_rewards(0, 100, &vote_state));
}
#[test]
fn test_stake_redeem_vote_credits() {
@ -168,7 +261,11 @@ mod tests {
vote_keyed_account.set_state(&vote_state).unwrap();
let pubkey = Pubkey::default();
let mut stake_account = Account::new(0, std::mem::size_of::<StakeState>(), &id());
let mut stake_account = Account::new(
STAKE_GETS_PAID_EVERY_VOTE,
std::mem::size_of::<StakeState>(),
&id(),
);
let mut stake_keyed_account = KeyedAccount::new(&pubkey, true, &mut stake_account);
// delegate the stake
@ -180,10 +277,10 @@ mod tests {
let mut mining_pool_keyed_account =
KeyedAccount::new(&pubkey, true, &mut mining_pool_account);
// no mining pool yet...
// not a mining pool yet...
assert_eq!(
mining_pool_keyed_account
.redeem_vote_credits(&mut stake_keyed_account, &vote_keyed_account),
.redeem_vote_credits(&mut stake_keyed_account, &mut vote_keyed_account),
Err(InstructionError::InvalidAccountData)
);
@ -193,25 +290,31 @@ mod tests {
// no movement in vote account, so no redemption needed
assert!(mining_pool_keyed_account
.redeem_vote_credits(&mut stake_keyed_account, &vote_keyed_account)
.redeem_vote_credits(&mut stake_keyed_account, &mut vote_keyed_account)
.is_ok());
// move the vote account forward
vote_state.process_vote(Vote::new(1000));
vote_keyed_account.set_state(&vote_state).unwrap();
// no lamports in the pool
// now, no lamports in the pool!
assert_eq!(
mining_pool_keyed_account
.redeem_vote_credits(&mut stake_keyed_account, &vote_keyed_account),
.redeem_vote_credits(&mut stake_keyed_account, &mut vote_keyed_account),
Err(InstructionError::UnbalancedInstruction)
);
// add a lamport
// add a lamport to pool
mining_pool_keyed_account.account.lamports = 2;
assert!(mining_pool_keyed_account
.redeem_vote_credits(&mut stake_keyed_account, &vote_keyed_account)
.is_ok());
.redeem_vote_credits(&mut stake_keyed_account, &mut vote_keyed_account)
.is_ok()); // yay
// lamports only shifted around, none made or lost
assert_eq!(
2 + 100 + STAKE_GETS_PAID_EVERY_VOTE,
mining_pool_account.lamports + vote_account.lamports + stake_account.lamports
);
}
#[test]
@ -252,7 +355,7 @@ mod tests {
// voter credits lower than stake_delegate credits... TODO: is this an error?
assert_eq!(
mining_pool_keyed_account
.redeem_vote_credits(&mut stake_keyed_account, &vote_keyed_account),
.redeem_vote_credits(&mut stake_keyed_account, &mut vote_keyed_account),
Err(InstructionError::InvalidAccountData)
);
@ -265,7 +368,7 @@ mod tests {
// wrong voter_id...
assert_eq!(
mining_pool_keyed_account
.redeem_vote_credits(&mut stake_keyed_account, &vote1_keyed_account),
.redeem_vote_credits(&mut stake_keyed_account, &mut vote1_keyed_account),
Err(InstructionError::InvalidArgument)
);
}

20
programs/vote_api/src/vote_state.rs
View File

@ -49,6 +49,9 @@ pub struct VoteState {
pub votes: VecDeque<Lockout>,
pub delegate_id: Pubkey,
pub authorized_voter_id: Pubkey,
/// fraction of std::u32::MAX that represents what part of a rewards
/// payout should be given to this VoteAccount
pub commission: u32,
pub root_slot: Option<u64>,
credits: u64,
}
@ -58,11 +61,13 @@ impl VoteState {
let votes = VecDeque::new();
let credits = 0;
let root_slot = None;
let commission = 0;
Self {
votes,
delegate_id: *staker_id,
authorized_voter_id: *staker_id,
credits,
commission,
root_slot,
}
}
@ -87,6 +92,21 @@ impl VoteState {
})
}
/// returns commission split as (voter_portion, staker_portion) tuple
///
/// if commission calculation is 100% one way or other,
/// indicate with None for the 0% side
pub fn commission_split(&self, on: f64) -> (f64, f64, bool) {
match self.commission {
0 => (0.0, on, false),
std::u32::MAX => (on, 0.0, false),
split => {
let mine = on * f64::from(split) / f64::from(std::u32::MAX);
(mine, on - mine, true)
}
}
}
pub fn process_vote(&mut self, vote: Vote) {
// Ignore votes for slots earlier than we already have votes for
if self