Skip to content
This repository has been archived by the owner on Jan 22, 2025. It is now read-only.

distribute leftover lamports #7396

Merged
merged 3 commits into from
Dec 10, 2019
Merged

distribute leftover lamports #7396

Changes from 1 commit
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
4a934b7
distribute leftover lamports
ParthDesai Dec 10, 2019
de8c93a
add test scenario
ParthDesai Dec 10, 2019
9c6b6ab
fix naming
ParthDesai Dec 10, 2019
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
52 changes: 41 additions & 11 deletions runtime/src/bank.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1259,8 +1259,9 @@ impl Bank {
rent_to_be_distributed: u64,
) {
let mut total_staked = 0;
let mut rent_distributed_in_initial_round = 0;

let node_stakes = vote_account_hashmap
let mut node_stakes = vote_account_hashmap
.iter()
.filter_map(|(_vote_pubkey, (staked, account))| {
total_staked += *staked;
Expand All @@ -1271,13 +1272,41 @@ impl Bank {
})
.collect::<Vec<(Pubkey, u64)>>();

node_stakes.iter().for_each(|(pubkey, staked)| {
let rent_to_be_paid =
(((staked * rent_to_be_distributed) as f64) / (total_staked as f64)) as u64;
let mut account = self.get_account(pubkey).unwrap_or_default();
account.lamports += rent_to_be_paid;
self.store_account(pubkey, &account);
});
// Sort first by stake and then by pubkey for determinism
node_stakes.sort_by(
|(pubkey1, staked1), (pubkey2, staked2)| match staked2.cmp(staked1) {
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

this sort doesn't need to be stable, does it? you should be safe sorting merely by stake...

Copy link
Contributor Author

@ParthDesai ParthDesai Dec 10, 2019 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@rob-solana If I sort by stake only, it could lead to indeterminism, as the order might not be guaranteed for node with same stake amount. Which could result in rare cases, different distribution of leftover lamports.

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

ah, good point.

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

are you testing for that?

Copy link
Contributor Author

@ParthDesai ParthDesai Dec 10, 2019 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@rob-solana not specifically. Let me add a separate test scenario for this, just for my assurance.

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@rob-solana Added a scenario in test-case.

std::cmp::Ordering::Equal => pubkey2.cmp(pubkey1),
other => other,
},
);

let node_stakes_and_rent = node_stakes
.iter()
.map(|(pubkey, staked)| {
let rent_in_initial_round =
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

rent_to_be_paid was just as good a name

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

could also be rent_share

(((*staked * rent_to_be_distributed) as f64) / (total_staked as f64)) as u64;
rent_distributed_in_initial_round += rent_in_initial_round;
(*pubkey, *staked, rent_in_initial_round)
})
.collect::<Vec<(Pubkey, u64, u64)>>();

// Leftover lamports after fraction calculation, will be paid to validators starting from highest stake
// holder
let mut leftover_lamports = rent_to_be_distributed - rent_distributed_in_initial_round;

node_stakes_and_rent
.iter()
.for_each(|(pubkey, _staked, rent)| {
let rent_to_be_paid = if leftover_lamports > 0 {
leftover_lamports -= 1;
*rent + 1
} else {
*rent
};
let mut account = self.get_account(pubkey).unwrap_or_default();
account.lamports += rent_to_be_paid;
self.store_account(pubkey, &account);
});
}

fn distribute_rent(&self) {
Expand Down Expand Up @@ -2321,19 +2350,20 @@ mod tests {
let rent_to_be_distributed = total_rent_deducted - burned_portion;

let bootstrap_leader_portion =
((bootstrap_leader_stake_lamports * rent_to_be_distributed) as f64 / 100.0) as u64;
((bootstrap_leader_stake_lamports * rent_to_be_distributed) as f64 / 100.0) as u64 + 1; // Leftover lamport
assert_eq!(
bank.get_balance(&bootstrap_leader_pubkey),
bootstrap_leader_portion + bootstrap_leader_initial_balance
);

let validator_1_portion =
((validator_1_stake_lamports * rent_to_be_distributed) as f64 / 100.0) as u64;
((validator_1_stake_lamports * rent_to_be_distributed) as f64 / 100.0) as u64 + 1;
assert_eq!(
bank.get_balance(&validator_1_pubkey),
validator_1_portion + 42
);

// No leftover lamport for you, as you have smallest of stake
let validator_2_portion =
((validator_2_stake_lamports * rent_to_be_distributed) as f64 / 100.0) as u64;
assert_eq!(
Expand All @@ -2342,7 +2372,7 @@ mod tests {
);

let validator_3_portion =
((validator_3_stake_lamports * rent_to_be_distributed) as f64 / 100.0) as u64;
((validator_3_stake_lamports * rent_to_be_distributed) as f64 / 100.0) as u64 + 1;
assert_eq!(
bank.get_balance(&validator_3_pubkey),
validator_3_portion + 42
Expand Down