diff --git a/polkadot/node/core/approval-voting/src/approval_checking.rs b/polkadot/node/core/approval-voting/src/approval_checking.rs
index d8384f88d4c9598c528ee097ec148d887e26d29e..4bdf3ffb6e1731a810f16a36f69d8a5c03480365 100644
--- a/polkadot/node/core/approval-voting/src/approval_checking.rs
+++ b/polkadot/node/core/approval-voting/src/approval_checking.rs
@@ -66,6 +66,8 @@ pub enum Check {
Unapproved,
/// The candidate is approved, with the given amount of no-shows.
Approved(usize),
+ /// The candidate is approved by one third of all validators.
+ ApprovedOneThird,
}
impl Check {
@@ -74,6 +76,15 @@ impl Check {
match *self {
Check::Unapproved => false,
Check::Approved(_) => true,
+ Check::ApprovedOneThird => true,
+ }
+ }
+
+ /// The number of known no-shows in this computation.
+ pub fn known_no_shows(&self) -> usize {
+ match *self {
+ Check::Approved(n) => n,
+ _ => 0,
}
}
}
@@ -84,16 +95,17 @@ pub fn check_approval(
approval: &ApprovalEntry,
required: RequiredTranches,
) -> Check {
+
+ // any set of size f+1 contains at least one honest node. If at least one
+ // honest node approves, the candidate should be approved.
+ let approvals = candidate.approvals();
+ if 3 * approvals.count_ones() > approvals.len() {
+ return Check::ApprovedOneThird;
+ }
+
match required {
RequiredTranches::Pending { .. } => Check::Unapproved,
- RequiredTranches::All => {
- let approvals = candidate.approvals();
- if 3 * approvals.count_ones() > 2 * approvals.len() {
- Check::Approved(0)
- } else {
- Check::Unapproved
- }
- }
+ RequiredTranches::All => Check::Unapproved,
RequiredTranches::Exact { needed, tolerated_missing, .. } => {
// whether all assigned validators up to `needed` less no_shows have approved.
// e.g. if we had 5 tranches and 1 no-show, we would accept all validators in
@@ -411,7 +423,7 @@ mod tests {
}
#[test]
- fn all_requires_supermajority() {
+ fn exact_takes_only_assignments_up_to() {
let mut candidate: CandidateEntry = approval_db::v1::CandidateEntry {
candidate: Default::default(),
session: 0,
@@ -419,26 +431,62 @@ mod tests {
approvals: bitvec![BitOrderLsb0, u8; 0; 10],
}.into();
- for i in 0..6 {
+ for i in 0..3 {
candidate.mark_approval(ValidatorIndex(i));
}
let approval_entry = approval_db::v1::ApprovalEntry {
- tranches: Vec::new(),
+ tranches: vec![
+ approval_db::v1::TrancheEntry {
+ tranche: 0,
+ assignments: (0..2).map(|i| (ValidatorIndex(i), 0.into())).collect(),
+ },
+ approval_db::v1::TrancheEntry {
+ tranche: 1,
+ assignments: (2..5).map(|i| (ValidatorIndex(i), 1.into())).collect(),
+ },
+ approval_db::v1::TrancheEntry {
+ tranche: 2,
+ assignments: (5..10).map(|i| (ValidatorIndex(i), 0.into())).collect(),
+ },
+ ],
assignments: bitvec![BitOrderLsb0, u8; 1; 10],
our_assignment: None,
backing_group: GroupIndex(0),
approved: false,
}.into();
- assert!(!check_approval(&candidate, &approval_entry, RequiredTranches::All).is_approved());
-
- candidate.mark_approval(ValidatorIndex(6));
- assert!(check_approval(&candidate, &approval_entry, RequiredTranches::All).is_approved());
+ assert!(check_approval(
+ &candidate,
+ &approval_entry,
+ RequiredTranches::Exact {
+ needed: 0,
+ tolerated_missing: 0,
+ next_no_show: None,
+ },
+ ).is_approved());
+ assert!(!check_approval(
+ &candidate,
+ &approval_entry,
+ RequiredTranches::Exact {
+ needed: 1,
+ tolerated_missing: 0,
+ next_no_show: None,
+ },
+ ).is_approved());
+ assert!(check_approval(
+ &candidate,
+ &approval_entry,
+ RequiredTranches::Exact {
+ needed: 1,
+ tolerated_missing: 2,
+ next_no_show: None,
+ },
+ ).is_approved());
}
#[test]
- fn exact_takes_only_assignments_up_to() {
+ fn one_honest_node_always_approves() {
let mut candidate: CandidateEntry = approval_db::v1::CandidateEntry {
candidate: Default::default(),
session: 0,
@@ -446,7 +494,7 @@ mod tests {
approvals: bitvec![BitOrderLsb0, u8; 0; 10],
}.into();
- for i in 0..6 {
+ for i in 0..3 {
candidate.mark_approval(ValidatorIndex(i));
}
@@ -471,32 +519,56 @@ mod tests {
approved: false,
}.into();
- assert!(check_approval(
+ let exact_all = RequiredTranches::Exact {
+ needed: 10,
+ tolerated_missing: 0,
+ next_no_show: None,
+ };
+
+ let pending_all = RequiredTranches::Pending {
+ considered: 5,
+ next_no_show: None,
+ maximum_broadcast: 8,
+ clock_drift: 12,
+ };
+
+ assert!(!check_approval(
&candidate,
&approval_entry,
- RequiredTranches::Exact {
- needed: 1,
- tolerated_missing: 0,
- next_no_show: None,
- },
+ RequiredTranches::All,
).is_approved());
+
assert!(!check_approval(
&candidate,
&approval_entry,
- RequiredTranches::Exact {
- needed: 2,
- tolerated_missing: 0,
- next_no_show: None,
- },
+ exact_all.clone(),
+ ).is_approved());
+
+ assert!(!check_approval(
+ &candidate,
+ &approval_entry,
+ pending_all.clone(),
).is_approved());
+
+ // This creates a set of 4/10 approvals, which is always an approval.
+ candidate.mark_approval(ValidatorIndex(3));
+
assert!(check_approval(
&candidate,
&approval_entry,
- RequiredTranches::Exact {
- needed: 2,
- tolerated_missing: 4,
- next_no_show: None,
- },
+ RequiredTranches::All,
+ ).is_approved());
+
+ assert!(check_approval(
+ &candidate,
+ &approval_entry,
+ exact_all,
+ ).is_approved());
+
+ assert!(check_approval(
+ &candidate,
+ &approval_entry,
+ pending_all,
).is_approved());
}
diff --git a/polkadot/node/core/approval-voting/src/lib.rs b/polkadot/node/core/approval-voting/src/lib.rs
index 87eda0ef972e6fe2ce417ef4a096b1fe87e07c5e..4ee997d77d8ec8aa5cb5985181d858df7b65f5e4 100644
--- a/polkadot/node/core/approval-voting/src/lib.rs
+++ b/polkadot/node/core/approval-voting/src/lib.rs
@@ -1316,7 +1316,7 @@ fn check_and_apply_full_approval(
required_tranches.clone(),
);
- if let approval_checking::Check::Approved(no_shows) = check {
+ if check.is_approved() {
tracing::trace!(
target: LOG_TARGET,
?candidate_hash,
@@ -1324,6 +1324,8 @@ fn check_and_apply_full_approval(
"Candidate approved under block.",
);
+ let no_shows = check.known_no_shows();
+
let was_approved = block_entry.is_fully_approved();
newly_approved.push(*block_hash);
diff --git a/polkadot/node/core/approval-voting/src/tests.rs b/polkadot/node/core/approval-voting/src/tests.rs
index 40d84d698a1805bef2598fbe7cded786e15fb758..9b9c153919fbc2ec1441a662762d9db3fd142dcf 100644
--- a/polkadot/node/core/approval-voting/src/tests.rs
+++ b/polkadot/node/core/approval-voting/src/tests.rs
@@ -869,7 +869,7 @@ fn check_and_apply_full_approval_does_not_load_cached_block_from_db() {
}
#[test]
-fn assignment_triggered_by_all_with_less_than_supermajority() {
+fn assignment_triggered_by_all_with_less_than_threshold() {
let block_hash = Hash::repeat_byte(0x01);
let mut candidate_entry: CandidateEntry = {
@@ -896,19 +896,13 @@ fn assignment_triggered_by_all_with_less_than_supermajority() {
}.into()
};
- // 2-of-4
+ // 1-of-4
candidate_entry
.approval_entry_mut(&block_hash)
.unwrap()
.import_assignment(0, ValidatorIndex(0), 0);
- candidate_entry
- .approval_entry_mut(&block_hash)
- .unwrap()
- .import_assignment(0, ValidatorIndex(1), 0);
-
candidate_entry.mark_approval(ValidatorIndex(0));
- candidate_entry.mark_approval(ValidatorIndex(1));
let tranche_now = 1;
assert!(should_trigger_assignment(
@@ -920,7 +914,7 @@ fn assignment_triggered_by_all_with_less_than_supermajority() {
}
#[test]
-fn assignment_not_triggered_by_all_with_supermajority() {
+fn assignment_not_triggered_by_all_with_threshold() {
let block_hash = Hash::repeat_byte(0x01);
let mut candidate_entry: CandidateEntry = {
@@ -947,7 +941,7 @@ fn assignment_not_triggered_by_all_with_supermajority() {
}.into()
};
- // 3-of-4
+ // 2-of-4
candidate_entry
.approval_entry_mut(&block_hash)
.unwrap()
@@ -958,14 +952,8 @@ fn assignment_not_triggered_by_all_with_supermajority() {
.unwrap()
.import_assignment(0, ValidatorIndex(1), 0);
- candidate_entry
- .approval_entry_mut(&block_hash)
- .unwrap()
- .import_assignment(0, ValidatorIndex(2), 0);
-
candidate_entry.mark_approval(ValidatorIndex(0));
candidate_entry.mark_approval(ValidatorIndex(1));
- candidate_entry.mark_approval(ValidatorIndex(2));
let tranche_now = 1;
assert!(!should_trigger_assignment(
diff --git a/polkadot/roadmap/implementers-guide/src/node/approval/approval-voting.md b/polkadot/roadmap/implementers-guide/src/node/approval/approval-voting.md
index b2b9a243b2a716dcdedf926c29aa721f1541b318..dd6994caea790db61170eee14a71bebb2b22abd5 100644
--- a/polkadot/roadmap/implementers-guide/src/node/approval/approval-voting.md
+++ b/polkadot/roadmap/implementers-guide/src/node/approval/approval-voting.md
@@ -360,8 +360,9 @@ Likewise, when considering how many tranches to take, the no-show depth should b
#### Check Approval
* Check whether a candidate is approved under a particular block.
* Requires `(block_entry, candidate_entry, approval_entry, n_tranches)`
+ * If we have `3 * n_approvals > n_validators`, return true. This is because any set with f+1 validators must have at least one honest validator, who has approved the candidate.
* If `n_tranches` is `RequiredTranches::Pending`, return false
- * If `n_tranches` is `RequiredTranches::All`, then we return `3 * n_approvals > 2 * n_validators`.
+ * If `n_tranches` is `RequiredTranches::All`, return false.
* If `n_tranches` is `RequiredTranches::Exact { tranche, tolerated_missing, .. }`, then we return whether all assigned validators up to `tranche` less `tolerated_missing` have approved. e.g. if we had 5 tranches and 1 tolerated missing, we would accept only if all but 1 of assigned validators in tranches 0..=5 have approved. In that example, we also accept all validators in tranches 0..=5 having approved, but that would indicate that the `RequiredTranches` value was incorrectly constructed, so it is not realistic. `tolerated_missing` actually represents covered no-shows. If there are more missing approvals than there are tolerated missing, that indicates that there are some assignments which are not yet no-shows, but may become no-shows, and we should wait for the validators to either approve or become no-shows.
### Time