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Improve performance of root slot in slot hashes history check (#22990)

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* Fold the root slot check into loop for performance

* Add assert in case vote state root is not older than slot hashes
This commit is contained in:
Ashwin Sekar
2022-02-15 19:17:56 -08:00
committed by GitHub
parent 56e23432b0
commit 6ae87109d2
1 changed files with 63 additions and 16 deletions
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71
programs/vote/src/vote_state/mod.rs
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@ -473,17 +473,12 @@ impl VoteState {
// to the current vote state root for safety.
if earliest_slot_hash_in_history > new_proposed_root {
vote_state_update.root = self.root_slot;
} else if !slot_hashes
// Verify that the root is in slot hashes
.iter()
.any(|&(slot, _)| slot == new_proposed_root)
{
return Err(VoteError::RootOnDifferentFork);
}
}
// index into the new proposed vote state's slots, starting at the oldest
// slot
// index into the new proposed vote state's slots, starting with the root if it exists then
// we use this mutable root to fold the root slot case into this loop for performance
let mut check_root = vote_state_update.root;
let mut vote_state_update_index = 0;
// index into the slot_hashes, starting at the oldest known
@ -505,8 +500,13 @@ impl VoteState {
// because have to ensure that every slot is actually part of the history, not just the most
// recent ones
while vote_state_update_index < vote_state_update.lockouts.len() && slot_hashes_index > 0 {
let proposed_vote_slot = vote_state_update.lockouts[vote_state_update_index].slot;
if vote_state_update_index > 0
let proposed_vote_slot = if let Some(root) = check_root {
root
} else {
vote_state_update.lockouts[vote_state_update_index].slot
};
if check_root.is_none()
&& vote_state_update_index > 0
&& proposed_vote_slot
<= vote_state_update.lockouts[vote_state_update_index - 1].slot
{
@ -522,7 +522,7 @@ impl VoteState {
// The vote slot does not exist in the SlotHashes history because it's too old,
// i.e. older than the oldest slot in the history.
assert!(proposed_vote_slot < earliest_slot_hash_in_history);
if !self.contains_slot(proposed_vote_slot) {
if !self.contains_slot(proposed_vote_slot) && check_root.is_none() {
// If the vote slot is both:
// 1) Too old
// 2) Doesn't already exist in vote state
@ -530,15 +530,27 @@ impl VoteState {
// Then filter it out
vote_state_update_indexes_to_filter.push(vote_state_update_index);
}
if check_root.is_some() {
// If the vote state update has a root < earliest_slot_hash_in_history
// then we use the current root. The only case where this can happen
// is if the current root itself is not in slot hashes.
assert!(self.root_slot.unwrap() < earliest_slot_hash_in_history);
check_root = None;
} else {
vote_state_update_index += 1;
}
continue;
} else {
// If the vote slot is new enough to be in the slot history,
// but is not part of the slot history, then it must belong to another fork,
// which means this vote state update is invalid.
if check_root.is_some() {
return Err(VoteError::RootOnDifferentFork);
} else {
return Err(VoteError::SlotsMismatch);
}
}
}
Ordering::Greater => {
// Decrement `slot_hashes_index` to find newer slots in the SlotHashes history
slot_hashes_index -= 1;
@ -546,12 +558,17 @@ impl VoteState {
}
Ordering::Equal => {
// Once the slot in `vote_state_update.lockouts` is found, bump to the next slot
// in `vote_state_update.lockouts` and continue.
// in `vote_state_update.lockouts` and continue. If we were checking the root,
// start checking the vote state instead.
if check_root.is_some() {
check_root = None;
} else {
vote_state_update_index += 1;
slot_hashes_index -= 1;
}
}
}
}
if vote_state_update_index != vote_state_update.lockouts.len() {
// The last vote slot in the update did not exist in SlotHashes
@ -4170,6 +4187,36 @@ mod tests {
);
}
#[test]
fn test_check_update_vote_state_root_on_different_fork() {
let slot_hashes = build_slot_hashes(vec![2, 4, 6, 8]);
let vote_state = build_vote_state(vec![2, 4, 6], &slot_hashes);
// Test with a `vote_state_update` where:
// 1) The root is not present in slot hashes history
// 2) The slot is greater than the earliest slot in the history
// Thus this slot is not part of the fork and the update should be rejected
// with error `RootOnDifferentFork`
let new_root = 3;
// Have to vote for a slot greater than the last vote in the vote state to avoid VoteTooOld
// errors
let vote_slot = vote_state.votes.back().unwrap().slot + 2;
let vote_slot_hash = slot_hashes
.iter()
.find(|(slot, _hash)| *slot == vote_slot)
.unwrap()
.1;
let mut vote_state_update = VoteStateUpdate::from(vec![(vote_slot, 1)]);
vote_state_update.hash = vote_slot_hash;
vote_state_update.root = Some(new_root);
assert_eq!(
vote_state
.check_update_vote_state_slots_are_valid(&mut vote_state_update, &slot_hashes),
Err(VoteError::RootOnDifferentFork),
);
}
#[test]
fn test_check_update_vote_state_slot_newer_than_slot_history() {
let slot_hashes = build_slot_hashes(vec![2, 4, 6, 8, 10]);