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abs: Snapshot requests are handled in priority-order (#27942)
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@brooksprumo
brooksprumo authored Sep 21, 2022
1 parent 999acb4 commit 5d71306
Showing 1 changed file with 197 additions and 4 deletions.
201 changes: 197 additions & 4 deletions runtime/src/accounts_background_service.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -115,6 +115,15 @@ pub struct SnapshotRequest {
pub request_type: SnapshotRequestType,
}

impl Debug for SnapshotRequest {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("SnapshotRequest")
.field("request type", &self.request_type)
.field("bank slot", &self.snapshot_root_bank.slot())
.finish()
}
}

/// What type of request is this?
///
/// The snapshot request has been expanded to support more than just snapshots. This is
Expand All @@ -141,10 +150,15 @@ impl SnapshotRequestHandler {
non_snapshot_time_us: u128,
last_full_snapshot_slot: &mut Option<Slot>,
) -> Option<Result<u64, SnapshotError>> {
self.snapshot_request_receiver
.try_iter()
.last()
.map(|snapshot_request| {
self.snapshot_request_receiver.try_iter()
.map(|request| {
let accounts_package_type = new_accounts_package_type(&request, &self.snapshot_config, *last_full_snapshot_slot);
(request, accounts_package_type)
})
.inspect(|(request, package_type)| trace!("outstanding snapshot request: {:?}, {:?}", request, package_type))
.max_by(cmp_snapshot_requests)
.map(|(snapshot_request, accounts_package_type)| {
trace!("handling snapshot request: {:?}, {:?}", snapshot_request, accounts_package_type);
let mut total_time = Measure::start("snapshot_request_receiver_total_time");
let accounts_package_type = new_accounts_package_type(&snapshot_request, &self.snapshot_config, *last_full_snapshot_slot);
let SnapshotRequest {
Expand Down Expand Up @@ -615,6 +629,53 @@ fn new_accounts_package_type(
}
}

/// Compare snapshot requests; used to pick the highest priority request to handle.
///
/// Priority, from highest to lowest:
/// - Epoch Accounts Hash
/// - Full Snapshot
/// - Incremental Snapshot
/// - Accounts Hash Verifier
///
/// If two snapshots of the same type are being compared, their bank slots are tiebreakers.
#[must_use]
fn cmp_snapshot_requests(
a: &(SnapshotRequest, AccountsPackageType),
b: &(SnapshotRequest, AccountsPackageType),
) -> std::cmp::Ordering {
let (snapshot_request_a, accounts_package_type_a) = a;
let (snapshot_request_b, accounts_package_type_b) = b;
let slot_a = snapshot_request_a.snapshot_root_bank.slot();
let slot_b = snapshot_request_b.snapshot_root_bank.slot();

use {AccountsPackageType::*, SnapshotType::*};
match (accounts_package_type_a, accounts_package_type_b) {
// Epoch Accounts Hash packages
(EpochAccountsHash, EpochAccountsHash) => {
panic!("Only a single EAH snapshot request is allowed at a time")
}
(EpochAccountsHash, _) => std::cmp::Ordering::Greater,
(_, EpochAccountsHash) => std::cmp::Ordering::Less,

// Snapshot packages
(Snapshot(snapshot_type_a), Snapshot(snapshot_type_b)) => {
match (snapshot_type_a, snapshot_type_b) {
(FullSnapshot, FullSnapshot) => slot_a.cmp(&slot_b),
(FullSnapshot, IncrementalSnapshot(_)) => std::cmp::Ordering::Greater,
(IncrementalSnapshot(_), FullSnapshot) => std::cmp::Ordering::Less,
(IncrementalSnapshot(base_slot_a), IncrementalSnapshot(base_slot_b)) => {
slot_a.cmp(&slot_b).then(base_slot_a.cmp(base_slot_b))
}
}
}
(Snapshot(_), _) => std::cmp::Ordering::Greater,
(_, Snapshot(_)) => std::cmp::Ordering::Less,

// Accounts Hash Verifier packages
(AccountsHashVerifier, AccountsHashVerifier) => slot_a.cmp(&slot_b),
}
}

#[cfg(test)]
mod test {
use {
Expand Down Expand Up @@ -648,4 +709,136 @@ mod test {

assert!(bank0.rc.accounts.scan_slot(0, |_| Some(())).is_empty());
}

#[test]
fn test_cmp_snapshot_requests() {
let genesis_config_info = create_genesis_config(10);
let bank = Arc::new(Bank::new_for_tests(&genesis_config_info.genesis_config));

for (accounts_package_type_a, accounts_package_type_b, expected_result) in [
(
AccountsPackageType::EpochAccountsHash,
AccountsPackageType::Snapshot(SnapshotType::FullSnapshot),
std::cmp::Ordering::Greater,
),
(
AccountsPackageType::EpochAccountsHash,
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(5)),
std::cmp::Ordering::Greater,
),
(
AccountsPackageType::EpochAccountsHash,
AccountsPackageType::AccountsHashVerifier,
std::cmp::Ordering::Greater,
),
(
AccountsPackageType::Snapshot(SnapshotType::FullSnapshot),
AccountsPackageType::EpochAccountsHash,
std::cmp::Ordering::Less,
),
(
AccountsPackageType::Snapshot(SnapshotType::FullSnapshot),
AccountsPackageType::Snapshot(SnapshotType::FullSnapshot),
std::cmp::Ordering::Equal,
),
(
AccountsPackageType::Snapshot(SnapshotType::FullSnapshot),
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(5)),
std::cmp::Ordering::Greater,
),
(
AccountsPackageType::Snapshot(SnapshotType::FullSnapshot),
AccountsPackageType::AccountsHashVerifier,
std::cmp::Ordering::Greater,
),
(
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(5)),
AccountsPackageType::EpochAccountsHash,
std::cmp::Ordering::Less,
),
(
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(5)),
AccountsPackageType::Snapshot(SnapshotType::FullSnapshot),
std::cmp::Ordering::Less,
),
(
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(5)),
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(6)),
std::cmp::Ordering::Less,
),
(
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(5)),
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(5)),
std::cmp::Ordering::Equal,
),
(
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(5)),
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(4)),
std::cmp::Ordering::Greater,
),
(
AccountsPackageType::Snapshot(SnapshotType::IncrementalSnapshot(5)),
AccountsPackageType::AccountsHashVerifier,
std::cmp::Ordering::Greater,
),
(
AccountsPackageType::AccountsHashVerifier,
AccountsPackageType::AccountsHashVerifier,
std::cmp::Ordering::Equal,
),
] {
let snapshot_request_a = SnapshotRequest {
snapshot_root_bank: Arc::clone(&bank),
status_cache_slot_deltas: Vec::default(),
request_type: new_snapshot_request_type(&accounts_package_type_a),
};
let snapshot_request_b = SnapshotRequest {
snapshot_root_bank: Arc::clone(&bank),
status_cache_slot_deltas: Vec::default(),
request_type: new_snapshot_request_type(&accounts_package_type_b),
};

let request_a = &(snapshot_request_a, accounts_package_type_a);
let request_b = &(snapshot_request_b, accounts_package_type_b);

let actual_result = cmp_snapshot_requests(request_a, request_b);
assert_eq!(expected_result, actual_result);
}
}

#[test]
#[should_panic]
fn test_cmp_snapshot_requests_both_eah() {
let genesis_config_info = create_genesis_config(10);
let bank = Arc::new(Bank::new_for_tests(&genesis_config_info.genesis_config));

let accounts_package_type_a = AccountsPackageType::EpochAccountsHash;
let accounts_package_type_b = AccountsPackageType::EpochAccountsHash;

let snapshot_request_a = SnapshotRequest {
snapshot_root_bank: Arc::clone(&bank),
status_cache_slot_deltas: Vec::default(),
request_type: new_snapshot_request_type(&accounts_package_type_a),
};
let snapshot_request_b = SnapshotRequest {
snapshot_root_bank: Arc::clone(&bank),
status_cache_slot_deltas: Vec::default(),
request_type: new_snapshot_request_type(&accounts_package_type_b),
};

let request_a = &(snapshot_request_a, accounts_package_type_a);
let request_b = &(snapshot_request_b, accounts_package_type_b);

let _ = cmp_snapshot_requests(request_a, request_b);
}

fn new_snapshot_request_type(
accounts_package_type: &AccountsPackageType,
) -> SnapshotRequestType {
match accounts_package_type {
AccountsPackageType::AccountsHashVerifier => SnapshotRequestType::Snapshot,
AccountsPackageType::Snapshot(_) => SnapshotRequestType::Snapshot,
AccountsPackageType::EpochAccountsHash => SnapshotRequestType::EpochAccountsHash,
}
}
}

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