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fix(paxos): Proposers don't re-commit entries before the latest checkpoint #1615

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merged 8 commits into from
Jan 9, 2025
Merged

fix(paxos): Proposers don't re-commit entries before the latest checkpoint #1615

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40315fd
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davidchuyaya Dec 19, 2024
680244e
Cargo clippy and fmt
davidchuyaya Dec 19, 2024
0348e42
Paxos snapshot updated
davidchuyaya Dec 19, 2024
182934d
Merge branch 'main' into paxos_proposer_checkpoint_bug
davidchuyaya Jan 8, 2025
f8d81a5
Changed from using signed int to Option<usize>
davidchuyaya Jan 8, 2025
3787c0d
More snapshots
davidchuyaya Jan 8, 2025
651801e
Use map().max() instead of fold_commutative()
davidchuyaya Jan 9, 2025
01451be
cargo fmt
davidchuyaya Jan 9, 2025
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70 changes: 50 additions & 20 deletions hydro_test/src/cluster/paxos.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -180,11 +180,11 @@ unsafe fn leader_election<'a, L: Clone + Debug + Serialize + DeserializeOwned>(
i_am_leader_check_timeout: u64,
i_am_leader_check_timeout_delay_multiplier: usize,
p_received_p2b_ballots: Stream<Ballot, Cluster<'a, Proposer>, Unbounded, NoOrder>,
a_log: Singleton<L, Tick<Cluster<'a, Acceptor>>, Bounded>,
a_log: Singleton<(Option<usize>, L), Tick<Cluster<'a, Acceptor>>, Bounded>,
) -> (
Singleton<Ballot, Tick<Cluster<'a, Proposer>>, Bounded>,
Optional<(), Tick<Cluster<'a, Proposer>>, Bounded>,
Stream<L, Tick<Cluster<'a, Proposer>>, Bounded, NoOrder>,
Stream<(Option<usize>, L), Tick<Cluster<'a, Proposer>>, Bounded, NoOrder>,
Singleton<Ballot, Tick<Cluster<'a, Acceptor>>, Bounded>,
) {
let (p1b_fail_complete, p1b_fail) =
Expand Down Expand Up @@ -372,11 +372,11 @@ unsafe fn p_leader_heartbeat<'a>(
fn acceptor_p1<'a, L: Serialize + DeserializeOwned + Clone>(
acceptor_tick: &Tick<Cluster<'a, Acceptor>>,
p_to_acceptors_p1a: Stream<Ballot, Tick<Cluster<'a, Acceptor>>, Bounded, NoOrder>,
a_log: Singleton<L, Tick<Cluster<'a, Acceptor>>, Bounded>,
a_log: Singleton<(Option<usize>, L), Tick<Cluster<'a, Acceptor>>, Bounded>,
proposers: &Cluster<'a, Proposer>,
) -> (
Singleton<Ballot, Tick<Cluster<'a, Acceptor>>, Bounded>,
Stream<(Ballot, Result<L, Ballot>), Cluster<'a, Proposer>, Unbounded, NoOrder>,
Stream<(Ballot, Result<(Option<usize>, L), Ballot>), Cluster<'a, Proposer>, Unbounded, NoOrder>,
) {
let a_max_ballot = p_to_acceptors_p1a
.clone()
Expand Down Expand Up @@ -414,7 +414,7 @@ fn acceptor_p1<'a, L: Serialize + DeserializeOwned + Clone>(
fn p_p1b<'a, P: Clone + Serialize + DeserializeOwned>(
proposer_tick: &Tick<Cluster<'a, Proposer>>,
a_to_proposers_p1b: Stream<
(Ballot, Result<P, Ballot>),
(Ballot, Result<(Option<usize>, P), Ballot>),
Cluster<'a, Proposer>,
Unbounded,
NoOrder,
Expand All @@ -424,7 +424,7 @@ fn p_p1b<'a, P: Clone + Serialize + DeserializeOwned>(
f: usize,
) -> (
Optional<(), Tick<Cluster<'a, Proposer>>, Bounded>,
Stream<P, Tick<Cluster<'a, Proposer>>, Bounded, NoOrder>,
Stream<(Option<usize>, P), Tick<Cluster<'a, Proposer>>, Bounded, NoOrder>,
Stream<Ballot, Timestamped<Cluster<'a, Proposer>>, Unbounded, NoOrder>,
) {
let (quorums, fails) = collect_quorum_with_response(
Expand Down Expand Up @@ -472,7 +472,7 @@ fn p_p1b<'a, P: Clone + Serialize + DeserializeOwned>(
#[expect(clippy::type_complexity, reason = "internal paxos code // TODO")]
fn recommit_after_leader_election<'a, P: PaxosPayload>(
accepted_logs: Stream<
HashMap<usize, LogValue<P>>,
(Option<usize>, HashMap<usize, LogValue<P>>),
Tick<Cluster<'a, Proposer>>,
Bounded,
NoOrder,
Expand All @@ -483,7 +483,22 @@ fn recommit_after_leader_election<'a, P: PaxosPayload>(
Stream<P2a<P>, Tick<Cluster<'a, Proposer>>, Bounded, NoOrder>,
Optional<usize, Tick<Cluster<'a, Proposer>>, Bounded>,
) {
let p_p1b_max_checkpoint = accepted_logs.clone().fold_commutative(
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In theory you could replace this with a .map().flatten().max().

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Doesn't this change behavior from a stream that contains either None or Some(checkpoint) to an Optional stream that may contain checkpoint? Because then the later join with p_log_to_try_commit won't go through if there is no checkpoint right? Without the flatten maybe it's ok?

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True! You can fix this by adding an addition .into_singleton() which should convert the Optional<T> into Singleton<Option<T>>.

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I'll just do map().max(), since Some(anything) > None so it works out

q!(|| None),
q!(|curr_max, (checkpoint, _log)| {
if let Some(checkpoint) = checkpoint {
if let Some(curr_max_val) = *curr_max {
if checkpoint > curr_max_val {
*curr_max = Some(checkpoint);
}
} else {
*curr_max = Some(checkpoint);
}
}
}),
);
let p_p1b_highest_entries_and_count = accepted_logs
.map(q!(|(_checkpoint, log)| log))
.flatten_unordered() // Convert HashMap log back to stream
.fold_keyed_commutative::<(usize, Option<LogValue<P>>), _, _>(q!(|| (0, None)), q!(|curr_entry, new_entry| {
if let Some(curr_entry_payload) = &mut curr_entry.1 {
Expand All @@ -510,16 +525,20 @@ fn recommit_after_leader_election<'a, P: PaxosPayload>(
let p_log_to_try_commit = p_p1b_highest_entries_and_count
.clone()
.cross_singleton(p_ballot.clone())
.filter_map(q!(move |((slot, (count, entry)), ballot)| {
if count <= f {
Some(P2a {
ballot,
slot,
value: entry.value,
})
} else {
None
.cross_singleton(p_p1b_max_checkpoint.clone())
.filter_map(q!(move |(((slot, (count, entry)), ballot), checkpoint)| {
if count > f {
return None;
} else if let Some(checkpoint) = checkpoint {
if slot <= checkpoint {
return None;
}
}
Some(P2a {
ballot,
slot,
value: entry.value,
})
}));
let p_max_slot = p_p1b_highest_entries_and_count
.clone()
Expand All @@ -530,7 +549,14 @@ fn recommit_after_leader_election<'a, P: PaxosPayload>(
.map(q!(|(slot, _)| slot));
let p_log_holes = p_max_slot
.clone()
.flat_map_ordered(q!(|max_slot| 0..max_slot))
.zip(p_p1b_max_checkpoint)
.flat_map_ordered(q!(|(max_slot, checkpoint)| {
if let Some(checkpoint) = checkpoint {
(checkpoint + 1)..max_slot
} else {
0..max_slot
}
}))
.filter_not_in(p_proposed_slots)
.cross_singleton(p_ballot.clone())
.map(q!(|(slot, ballot)| P2a {
Expand Down Expand Up @@ -564,7 +590,7 @@ unsafe fn sequence_payload<'a, P: PaxosPayload, R>(
p_is_leader: Optional<(), Tick<Cluster<'a, Proposer>>, Bounded>,

p_relevant_p1bs: Stream<
HashMap<usize, LogValue<P>>,
(Option<usize>, HashMap<usize, LogValue<P>>),
Tick<Cluster<'a, Proposer>>,
Bounded,
NoOrder,
Expand All @@ -574,7 +600,11 @@ unsafe fn sequence_payload<'a, P: PaxosPayload, R>(
a_max_ballot: Singleton<Ballot, Tick<Cluster<'a, Acceptor>>, Bounded>,
) -> (
Stream<(usize, Option<P>), Cluster<'a, Proposer>, Unbounded, NoOrder>,
Singleton<HashMap<usize, LogValue<P>>, Timestamped<Cluster<'a, Acceptor>>, Unbounded>,
Singleton<
(Option<usize>, HashMap<usize, LogValue<P>>),
Timestamped<Cluster<'a, Acceptor>>,
Unbounded,
>,
Stream<Ballot, Cluster<'a, Proposer>, Unbounded, NoOrder>,
) {
let (p_log_to_recommit, p_max_slot) =
Expand Down Expand Up @@ -635,7 +665,7 @@ unsafe fn sequence_payload<'a, P: PaxosPayload, R>(
p_to_replicas
.map(q!(|((slot, _ballot), (value, _))| (slot, value)))
.drop_timestamp(),
a_log.map(q!(|(_ckpnt, log)| log)),
a_log,
fails.map(q!(|(_, ballot)| ballot)).drop_timestamp(),
)
}
Expand Down
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