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Correct Bank timestamp drift every slot (#12737)

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* Move timestamp helper to sdk

* Add Bank method for getting timestamp estimate

* Return sysvar info from Bank::clock

* Add feature-gated timestamp correction

* Rename unix_timestamp method to be more descriptive

* Review comments

* Add timestamp metric
This commit is contained in:
Tyera Eulberg
2020-10-09 15:53:41 -06:00
committed by GitHub
parent ed95071c27
commit b028c47d2b
5 changed files with 418 additions and 152 deletions
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1
sdk/src/lib.rs
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@ -45,6 +45,7 @@ pub mod short_vec;
pub mod slot_hashes;
pub mod slot_history;
pub mod stake_history;
pub mod stake_weighted_timestamp;
pub mod system_instruction;
pub mod system_program;
pub mod sysvar;

150
sdk/src/stake_weighted_timestamp.rs Normal file
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@ -0,0 +1,150 @@
/// A helper for calculating a stake-weighted timestamp estimate from a set of timestamps and epoch
/// stake.
use solana_sdk::{
account::Account,
clock::{Slot, UnixTimestamp},
pubkey::Pubkey,
};
use std::{collections::HashMap, time::Duration};
pub const TIMESTAMP_SLOT_RANGE: usize = 16;
pub fn calculate_stake_weighted_timestamp(
unique_timestamps: &HashMap<Pubkey, (Slot, UnixTimestamp)>,
stakes: &HashMap<Pubkey, (u64, Account)>,
slot: Slot,
slot_duration: Duration,
) -> Option<UnixTimestamp> {
let (stake_weighted_timestamps_sum, total_stake) = unique_timestamps
.iter()
.filter_map(|(vote_pubkey, (timestamp_slot, timestamp))| {
let offset = (slot - timestamp_slot) as u32 * slot_duration;
stakes.get(&vote_pubkey).map(|(stake, _account)| {
(
(*timestamp as u128 + offset.as_secs() as u128) * *stake as u128,
stake,
)
})
})
.fold((0, 0), |(timestamps, stakes), (timestamp, stake)| {
(timestamps + timestamp, stakes + *stake as u128)
});
if total_stake > 0 {
Some((stake_weighted_timestamps_sum / total_stake) as i64)
} else {
None
}
}
#[cfg(test)]
pub mod tests {
use super::*;
use solana_sdk::native_token::sol_to_lamports;
#[test]
fn test_calculate_stake_weighted_timestamp() {
let recent_timestamp: UnixTimestamp = 1_578_909_061;
let slot = 5;
let slot_duration = Duration::from_millis(400);
let expected_offset = (slot * slot_duration).as_secs();
let pubkey0 = Pubkey::new_rand();
let pubkey1 = Pubkey::new_rand();
let pubkey2 = Pubkey::new_rand();
let pubkey3 = Pubkey::new_rand();
let unique_timestamps: HashMap<Pubkey, (Slot, UnixTimestamp)> = [
(pubkey0, (0, recent_timestamp)),
(pubkey1, (0, recent_timestamp)),
(pubkey2, (0, recent_timestamp)),
(pubkey3, (0, recent_timestamp)),
]
.iter()
.cloned()
.collect();
let stakes: HashMap<Pubkey, (u64, Account)> = [
(
pubkey0,
(
sol_to_lamports(4_500_000_000.0),
Account::new(1, 0, &Pubkey::default()),
),
),
(
pubkey1,
(
sol_to_lamports(4_500_000_000.0),
Account::new(1, 0, &Pubkey::default()),
),
),
(
pubkey2,
(
sol_to_lamports(4_500_000_000.0),
Account::new(1, 0, &Pubkey::default()),
),
),
(
pubkey3,
(
sol_to_lamports(4_500_000_000.0),
Account::new(1, 0, &Pubkey::default()),
),
),
]
.iter()
.cloned()
.collect();
assert_eq!(
calculate_stake_weighted_timestamp(
&unique_timestamps,
&stakes,
slot as Slot,
slot_duration
),
Some(recent_timestamp + expected_offset as i64)
);
let stakes: HashMap<Pubkey, (u64, Account)> = [
(
pubkey0,
(
sol_to_lamports(15_000_000_000.0),
Account::new(1, 0, &Pubkey::default()),
),
),
(
pubkey1,
(
sol_to_lamports(1_000_000_000.0),
Account::new(1, 0, &Pubkey::default()),
),
),
(
pubkey2,
(
sol_to_lamports(1_000_000_000.0),
Account::new(1, 0, &Pubkey::default()),
),
),
(
pubkey3,
(
sol_to_lamports(1_000_000_000.0),
Account::new(1, 0, &Pubkey::default()),
),
),
]
.iter()
.cloned()
.collect();
assert_eq!(
calculate_stake_weighted_timestamp(
&unique_timestamps,
&stakes,
slot as Slot,
slot_duration
),
Some(recent_timestamp + expected_offset as i64)
);
}
}