Request based availability distribution (#2423)

* WIP

* availability distribution, still very wip.

Work on the requesting side of things.

* Some docs on what I intend to do.

* Checkpoint of session cache implementation

as I will likely replace it with something smarter.

* More work, mostly on cache

and getting things to type check.

* Only derive MallocSizeOf and Debug for std.

* availability-distribution: Cache feature complete.

* Sketch out logic in `FetchTask` for actual fetching.

- Compile fixes.
- Cleanup.

* Format cleanup.

* More format fixes.

* Almost feature complete `fetch_task`.

Missing:

- Check for cancel
- Actual querying of peer ids.

* Finish FetchTask so far.

* Directly use AuthorityDiscoveryId in protocol and cache.

* Resolve `AuthorityDiscoveryId` on sending requests.

* Rework fetch_task

- also make it impossible to check the wrong chunk index.
- Export needed function in validator_discovery.

* From<u32> implementation for `ValidatorIndex`.

* Fixes and more integration work.

* Make session cache proper lru cache.

* Use proper lru cache.

* Requester finished.

* ProtocolState -> Requester

Also make sure to not fetch our own chunk.

* Cleanup + fixes.

* Remove unused functions

- FetchTask::is_finished
- SessionCache::fetch_session_info

* availability-distribution responding side.

* Cleanup + Fixes.

* More fixes.

* More fixes.

adder-collator is running!

* Some docs.

* Docs.

* Fix reporting of bad guys.

* Fix tests

* Make all tests compile.

* Fix test.

* Cleanup + get rid of some warnings.

* state -> requester

* Mostly doc fixes.

* Fix test suite.

* Get rid of now redundant message types.

* WIP

* Rob's review remarks.

* Fix test suite.

* core.relay_parent -> leaf for session request.

* Style fix.

* Decrease request timeout.

* Cleanup obsolete errors.

* Metrics + don't fail on non fatal errors.

* requester.rs -> requester/mod.rs

* Panic on invalid BadValidator report.

* Fix indentation.

* Use typed default timeout constant.

* Make channel size 0, as each sender gets one slot anyways.

* Fix incorrect metrics initialization.

* Fix build after merge.

* More fixes.

* Hopefully valid metrics names.

* Better metrics names.

* Some tests that already work.

* Slightly better docs.

* Some more tests.

* Fix network bridge test.

Cargo.lock

@@ -5087,15 +5087,19 @@ version = "0.1.0"
 dependencies = [
  "assert_matches",
  "futures 0.3.12",
+ "lru",
  "maplit",
  "parity-scale-codec",
  "polkadot-erasure-coding",
+ "polkadot-node-core-runtime-api",
  "polkadot-node-network-protocol",
  "polkadot-node-subsystem",
  "polkadot-node-subsystem-test-helpers",
  "polkadot-node-subsystem-util",
  "polkadot-primitives",
+ "rand 0.8.3",
  "sc-keystore",
+ "sc-network",
  "sp-application-crypto",
  "sp-core",
  "sp-keyring",

node/core/approval-voting/src/approval_checking.rs

@@ -306,7 +306,7 @@ pub fn tranches_to_approve(
 				assignments.iter()
 					.map(|(v_index, tick)| (v_index, tick.saturating_sub(clock_drift) + no_show_duration))
 					.filter(|&(v_index, no_show_at)| {
-						let has_approved = approvals.get(*v_index as usize).map(|b| *b).unwrap_or(false);
+						let has_approved = approvals.get(v_index.0 as usize).map(|b| *b).unwrap_or(false);
 
 						let is_no_show = !has_approved && no_show_at <= drifted_tick_now;
 
@@ -348,7 +348,7 @@ pub fn tranches_to_approve(
 mod tests {
 	use super::*;
 
-	use polkadot_primitives::v1::GroupIndex;
+	use polkadot_primitives::v1::{GroupIndex, ValidatorIndex};
 	use bitvec::bitvec;
 	use bitvec::order::Lsb0 as BitOrderLsb0;
 
@@ -393,7 +393,7 @@ mod tests {
 		}.into();
 
 		for i in 0..6 {
-			candidate.mark_approval(i);
+			candidate.mark_approval(ValidatorIndex(i));
 		}
 
 		let approval_entry = approval_db::v1::ApprovalEntry {
@@ -406,7 +406,7 @@ mod tests {
 
 		assert!(!check_approval(&candidate, &approval_entry, RequiredTranches::All));
 
-		candidate.mark_approval(6);
+		candidate.mark_approval(ValidatorIndex(6));
 		assert!(check_approval(&candidate, &approval_entry, RequiredTranches::All));
 	}
 
@@ -420,22 +420,22 @@ mod tests {
 		}.into();
 
 		for i in 0..6 {
-			candidate.mark_approval(i);
+			candidate.mark_approval(ValidatorIndex(i));
 		}
 
 		let approval_entry = approval_db::v1::ApprovalEntry {
 			tranches: vec![
 				approval_db::v1::TrancheEntry {
 					tranche: 0,
-					assignments: (0..4).map(|i| (i, 0.into())).collect(),
+					assignments: (0..4).map(|i| (ValidatorIndex(i), 0.into())).collect(),
 				},
 				approval_db::v1::TrancheEntry {
 					tranche: 1,
-					assignments: (4..6).map(|i| (i, 1.into())).collect(),
+					assignments: (4..6).map(|i| (ValidatorIndex(i), 1.into())).collect(),
 				},
 				approval_db::v1::TrancheEntry {
 					tranche: 2,
-					assignments: (6..10).map(|i| (i, 0.into())).collect(),
+					assignments: (6..10).map(|i| (ValidatorIndex(i), 0.into())).collect(),
 				},
 			],
 			assignments: bitvec![BitOrderLsb0, u8; 1; 10],
@@ -487,13 +487,13 @@ mod tests {
 			approved: false,
 		}.into();
 
-		approval_entry.import_assignment(0, 0, block_tick);
-		approval_entry.import_assignment(0, 1, block_tick);
+		approval_entry.import_assignment(0,ValidatorIndex(0), block_tick);
+		approval_entry.import_assignment(0,ValidatorIndex(1), block_tick);
 
-		approval_entry.import_assignment(1, 2, block_tick + 1);
-		approval_entry.import_assignment(1, 3, block_tick + 1);
+		approval_entry.import_assignment(1,ValidatorIndex(2), block_tick + 1);
+		approval_entry.import_assignment(1,ValidatorIndex(3), block_tick + 1);
 
-		approval_entry.import_assignment(2, 4, block_tick + 2);
+		approval_entry.import_assignment(2,ValidatorIndex(4), block_tick + 2);
 
 		let approvals = bitvec![BitOrderLsb0, u8; 1; 5];
 
@@ -524,8 +524,8 @@ mod tests {
 			approved: false,
 		}.into();
 
-		approval_entry.import_assignment(0, 0, block_tick);
-		approval_entry.import_assignment(1, 2, block_tick);
+		approval_entry.import_assignment(0, ValidatorIndex(0), block_tick);
+		approval_entry.import_assignment(1, ValidatorIndex(2), block_tick);
 
 		let approvals = bitvec![BitOrderLsb0, u8; 0; 10];
 
@@ -562,10 +562,10 @@ mod tests {
 			approved: false,
 		}.into();
 
-		approval_entry.import_assignment(0, 0, block_tick);
-		approval_entry.import_assignment(0, 1, block_tick);
+		approval_entry.import_assignment(0, ValidatorIndex(0), block_tick);
+		approval_entry.import_assignment(0, ValidatorIndex(1), block_tick);
 
-		approval_entry.import_assignment(1, 2, block_tick);
+		approval_entry.import_assignment(1, ValidatorIndex(2), block_tick);
 
 		let mut approvals = bitvec![BitOrderLsb0, u8; 0; 10];
 		approvals.set(0, true);
@@ -605,11 +605,11 @@ mod tests {
 			approved: false,
 		}.into();
 
-		approval_entry.import_assignment(0, 0, block_tick);
-		approval_entry.import_assignment(0, 1, block_tick);
+		approval_entry.import_assignment(0, ValidatorIndex(0), block_tick);
+		approval_entry.import_assignment(0, ValidatorIndex(1), block_tick);
 
-		approval_entry.import_assignment(1, 2, block_tick);
-		approval_entry.import_assignment(1, 3, block_tick);
+		approval_entry.import_assignment(1, ValidatorIndex(2), block_tick);
+		approval_entry.import_assignment(1, ValidatorIndex(3), block_tick);
 
 		let mut approvals = bitvec![BitOrderLsb0, u8; 0; n_validators];
 		approvals.set(0, true);
@@ -670,14 +670,14 @@ mod tests {
 			approved: false,
 		}.into();
 
-		approval_entry.import_assignment(0, 0, block_tick);
-		approval_entry.import_assignment(0, 1, block_tick);
+		approval_entry.import_assignment(0, ValidatorIndex(0), block_tick);
+		approval_entry.import_assignment(0, ValidatorIndex(1), block_tick);
 
-		approval_entry.import_assignment(1, 2, block_tick + 1);
-		approval_entry.import_assignment(1, 3, block_tick + 1);
+		approval_entry.import_assignment(1, ValidatorIndex(2), block_tick + 1);
+		approval_entry.import_assignment(1, ValidatorIndex(3), block_tick + 1);
 
-		approval_entry.import_assignment(2, 4, block_tick + no_show_duration + 2);
-		approval_entry.import_assignment(2, 5, block_tick + no_show_duration + 2);
+		approval_entry.import_assignment(2, ValidatorIndex(4), block_tick + no_show_duration + 2);
+		approval_entry.import_assignment(2, ValidatorIndex(5), block_tick + no_show_duration + 2);
 
 		let mut approvals = bitvec![BitOrderLsb0, u8; 0; n_validators];
 		approvals.set(0, true);
@@ -757,14 +757,14 @@ mod tests {
 			approved: false,
 		}.into();
 
-		approval_entry.import_assignment(0, 0, block_tick);
-		approval_entry.import_assignment(0, 1, block_tick);
+		approval_entry.import_assignment(0, ValidatorIndex(0), block_tick);
+		approval_entry.import_assignment(0, ValidatorIndex(1), block_tick);
 
-		approval_entry.import_assignment(1, 2, block_tick + 1);
-		approval_entry.import_assignment(1, 3, block_tick + 1);
+		approval_entry.import_assignment(1, ValidatorIndex(2), block_tick + 1);
+		approval_entry.import_assignment(1, ValidatorIndex(3), block_tick + 1);
 
-		approval_entry.import_assignment(2, 4, block_tick + no_show_duration + 2);
-		approval_entry.import_assignment(2, 5, block_tick + no_show_duration + 2);
+		approval_entry.import_assignment(2, ValidatorIndex(4), block_tick + no_show_duration + 2);
+		approval_entry.import_assignment(2, ValidatorIndex(5), block_tick + no_show_duration + 2);
 
 		let mut approvals = bitvec![BitOrderLsb0, u8; 0; n_validators];
 		approvals.set(0, true);
@@ -813,7 +813,7 @@ mod tests {
 			},
 		);
 
-		approval_entry.import_assignment(3, 6, block_tick);
+		approval_entry.import_assignment(3, ValidatorIndex(6), block_tick);
 		approvals.set(6, true);
 
 		let tranche_now = no_show_duration as DelayTranche + 3;

node/core/approval-voting/src/criteria.rs

@@ -253,7 +253,7 @@ pub(crate) fn compute_assignments(
 	let (index, assignments_key): (ValidatorIndex, AssignmentPair) = {
 		let key = config.assignment_keys.iter().enumerate()
 			.find_map(|(i, p)| match keystore.key_pair(p) {
-				Ok(Some(pair)) => Some((i as ValidatorIndex, pair)),
+				Ok(Some(pair)) => Some((ValidatorIndex(i as _), pair)),
 				Ok(None) => None,
 				Err(sc_keystore::Error::Unavailable) => None,
 				Err(sc_keystore::Error::Io(e)) if e.kind() == std::io::ErrorKind::NotFound => None,
@@ -422,7 +422,7 @@ pub(crate) fn check_assignment_cert(
 	backing_group: GroupIndex,
 ) -> Result<DelayTranche, InvalidAssignment> {
 	let validator_public = config.assignment_keys
-		.get(validator_index as usize)
+		.get(validator_index.0 as usize)
 		.ok_or(InvalidAssignment)?;
 
 	let public = schnorrkel::PublicKey::from_bytes(validator_public.as_slice())
@@ -540,7 +540,7 @@ mod tests {
 		(0..n_groups).map(|i| {
 			(i * size .. (i + 1) *size)
 				.chain(if i < big_groups { Some(scraps + i) } else { None })
-				.map(|j| j as ValidatorIndex)
+				.map(|j| ValidatorIndex(j as _))
 				.collect::<Vec<_>>()
 		}).collect()
 	}
@@ -570,7 +570,7 @@ mod tests {
 					Sr25519Keyring::Bob,
 					Sr25519Keyring::Charlie,
 				]),
-				validator_groups: vec![vec![0], vec![1, 2]],
+				validator_groups: vec![vec![ValidatorIndex(0)], vec![ValidatorIndex(1), ValidatorIndex(2)]],
 				n_cores: 2,
 				zeroth_delay_tranche_width: 10,
 				relay_vrf_modulo_samples: 3,
@@ -601,7 +601,7 @@ mod tests {
 					Sr25519Keyring::Bob,
 					Sr25519Keyring::Charlie,
 				]),
-				validator_groups: vec![vec![0], vec![1, 2]],
+				validator_groups: vec![vec![ValidatorIndex(0)], vec![ValidatorIndex(1), ValidatorIndex(2)]],
 				n_cores: 2,
 				zeroth_delay_tranche_width: 10,
 				relay_vrf_modulo_samples: 3,
@@ -693,7 +693,7 @@ mod tests {
 				group: group_for_core(core.0 as _),
 				cert: assignment.cert,
 				own_group: GroupIndex(0),
-				val_index: 0,
+				val_index: ValidatorIndex(0),
 				config: config.clone(),
 			};
 
@@ -743,7 +743,7 @@ mod tests {
 	#[test]
 	fn check_rejects_nonexistent_key() {
 		check_mutated_assignments(200, 100, 25, |m| {
-			m.val_index += 200;
+			m.val_index.0 += 200;
 			Some(false)
 		});
 	}

node/core/approval-voting/src/import.rs

@@ -707,6 +707,7 @@ mod tests {
 	use super::*;
 	use polkadot_node_subsystem_test_helpers::make_subsystem_context;
 	use polkadot_node_primitives::approval::{VRFOutput, VRFProof};
+	use polkadot_primitives::v1::ValidatorIndex;
 	use polkadot_subsystem::messages::AllMessages;
 	use sp_core::testing::TaskExecutor;
 	use sp_runtime::{Digest, DigestItem};
@@ -1561,7 +1562,7 @@ mod tests {
 			validators: vec![Sr25519Keyring::Alice.public().into(); 6],
 			discovery_keys: Vec::new(),
 			assignment_keys: Vec::new(),
-			validator_groups: vec![vec![0; 5], vec![0; 2]],
+			validator_groups: vec![vec![ValidatorIndex(0); 5], vec![ValidatorIndex(0); 2]],
 			n_cores: 6,
 			needed_approvals: 2,
 			zeroth_delay_tranche_width: irrelevant,

node/core/approval-voting/src/lib.rs

@@ -864,7 +864,7 @@ fn check_and_import_assignment(
 			tracing::trace!(
 				target: LOG_TARGET,
 				"Imported assignment from validator {} on candidate {:?}",
-				assignment.validator,
+				assignment.validator.0,
 				(assigned_candidate_hash, candidate_entry.candidate_receipt().descriptor.para_id),
 			);
 
@@ -928,7 +928,7 @@ fn check_and_import_approval<T>(
 		block_entry.session(),
 	);
 
-	let pubkey = match session_info.validators.get(approval.validator as usize) {
+	let pubkey = match session_info.validators.get(approval.validator.0 as usize) {
 		Some(k) => k,
 		None => respond_early!(ApprovalCheckResult::Bad)
 	};
@@ -1492,13 +1492,13 @@ async fn issue_approval(
 		}
 	};
 
-	let validator_pubkey = match session_info.validators.get(validator_index as usize) {
+	let validator_pubkey = match session_info.validators.get(validator_index.0 as usize) {
 		Some(p) => p,
 		None => {
 			tracing::warn!(
 				target: LOG_TARGET,
 				"Validator index {} out of bounds in session {}",
-				validator_index,
+				validator_index.0,
 				block_entry.session(),
 			);
 
@@ -1517,7 +1517,7 @@ async fn issue_approval(
 			tracing::warn!(
 				target: LOG_TARGET,
 				"Could not issue approval signature with validator index {} in session {}. Assignment key present but not validator key?",
-				validator_index,
+				validator_index.0,
 				block_entry.session(),
 			);
 

node/core/approval-voting/src/persisted_entries.rs

@@ -110,7 +110,7 @@ impl ApprovalEntry {
 
 	/// Whether a validator is already assigned.
 	pub fn is_assigned(&self, validator_index: ValidatorIndex) -> bool {
-		self.assignments.get(validator_index as usize).map(|b| *b).unwrap_or(false)
+		self.assignments.get(validator_index.0 as usize).map(|b| *b).unwrap_or(false)
 	}
 
 	/// Import an assignment. No-op if already assigned on the same tranche.
@@ -143,7 +143,7 @@ impl ApprovalEntry {
 		};
 
 		self.tranches[idx].assignments.push((validator_index, tick_now));
-		self.assignments.set(validator_index as _, true);
+		self.assignments.set(validator_index.0 as _, true);
 	}
 
 	// Produce a bitvec indicating the assignments of all validators up to and
@@ -153,7 +153,7 @@ impl ApprovalEntry {
 			.take_while(|e| e.tranche <= tranche)
 			.fold(bitvec::bitvec![BitOrderLsb0, u8; 0; self.assignments.len()], |mut a, e| {
 				for &(v, _) in &e.assignments {
-					a.set(v as _, true);
+					a.set(v.0 as _, true);
 				}
 
 				a
@@ -235,8 +235,8 @@ impl CandidateEntry {
 
 	/// Note that a given validator has approved. Return the previous approval state.
 	pub fn mark_approval(&mut self, validator: ValidatorIndex) -> bool {
-		let prev = self.approvals.get(validator as usize).map(|b| *b).unwrap_or(false);
-		self.approvals.set(validator as usize, true);
+		let prev = self.approvals.get(validator.0 as usize).map(|b| *b).unwrap_or(false);
+		self.approvals.set(validator.0 as usize, true);
 		prev
 	}
 

node/core/approval-voting/src/tests.rs

@@ -243,7 +243,7 @@ impl Default for StateConfig {
 			slot: Slot::from(0),
 			tick: 0,
 			validators: vec![Sr25519Keyring::Alice, Sr25519Keyring::Bob],
-			validator_groups: vec![vec![0], vec![1]],
+			validator_groups: vec![vec![ValidatorIndex(0)], vec![ValidatorIndex(1)]],
 			needed_approvals: 1,
 			no_show_slots: 2,
 		}
@@ -364,7 +364,7 @@ fn rejects_bad_assignment() {
 	let block_hash = Hash::repeat_byte(0x01);
 	let assignment_good = IndirectAssignmentCert {
 		block_hash,
-		validator: 0,
+		validator: ValidatorIndex(0),
 		cert: garbage_assignment_cert(
 			AssignmentCertKind::RelayVRFModulo {
 				sample: 0,
@@ -386,7 +386,7 @@ fn rejects_bad_assignment() {
 	// unknown hash
 	let assignment = IndirectAssignmentCert {
 		block_hash: Hash::repeat_byte(0x02),
-		validator: 0,
+		validator: ValidatorIndex(0),
 		cert: garbage_assignment_cert(
 			AssignmentCertKind::RelayVRFModulo {
 				sample: 0,
@@ -423,7 +423,7 @@ fn rejects_assignment_in_future() {
 	let candidate_index = 0;
 	let assignment = IndirectAssignmentCert {
 		block_hash,
-		validator: 0,
+		validator: ValidatorIndex(0),
 		cert: garbage_assignment_cert(
 			AssignmentCertKind::RelayVRFModulo {
 				sample: 0,
@@ -467,7 +467,7 @@ fn rejects_assignment_with_unknown_candidate() {
 	let candidate_index = 1;
 	let assignment = IndirectAssignmentCert {
 		block_hash,
-		validator: 0,
+		validator: ValidatorIndex(0),
 		cert: garbage_assignment_cert(
 			AssignmentCertKind::RelayVRFModulo {
 				sample: 0,
@@ -493,7 +493,7 @@ fn assignment_import_updates_candidate_entry_and_schedules_wakeup() {
 	let candidate_index = 0;
 	let assignment = IndirectAssignmentCert {
 		block_hash,
-		validator: 0,
+		validator: ValidatorIndex(0),
 		cert: garbage_assignment_cert(
 			AssignmentCertKind::RelayVRFModulo {
 				sample: 0,
@@ -534,7 +534,7 @@ fn assignment_import_updates_candidate_entry_and_schedules_wakeup() {
 		actions.get(1).unwrap(),
 		Action::WriteCandidateEntry(c, e) => {
 			assert_eq!(c, &candidate_hash);
-			assert!(e.approval_entry(&block_hash).unwrap().is_assigned(0));
+			assert!(e.approval_entry(&block_hash).unwrap().is_assigned(ValidatorIndex(0)));
 		}
 	);
 }
@@ -554,7 +554,7 @@ fn rejects_approval_before_assignment() {
 	let vote = IndirectSignedApprovalVote {
 		block_hash,
 		candidate_index: 0,
-		validator: 0,
+		validator: ValidatorIndex(0),
 		signature: sign_approval(Sr25519Keyring::Alice, candidate_hash, 1),
 	};
 
@@ -583,7 +583,7 @@ fn rejects_approval_if_no_candidate_entry() {
 	let vote = IndirectSignedApprovalVote {
 		block_hash,
 		candidate_index: 0,
-		validator: 0,
+		validator: ValidatorIndex(0),
 		signature: sign_approval(Sr25519Keyring::Alice, candidate_hash, 1),
 	};
 
@@ -603,7 +603,7 @@ fn rejects_approval_if_no_candidate_entry() {
 fn rejects_approval_if_no_block_entry() {
 	let block_hash = Hash::repeat_byte(0x01);
 	let candidate_hash = CandidateHash(Hash::repeat_byte(0xCC));
-	let validator_index = 0;
+	let validator_index = ValidatorIndex(0);
 
 	let mut state = State {
 		assignment_criteria: Box::new(MockAssignmentCriteria::check_only(|| {
@@ -615,7 +615,7 @@ fn rejects_approval_if_no_block_entry() {
 	let vote = IndirectSignedApprovalVote {
 		block_hash,
 		candidate_index: 0,
-		validator: 0,
+		validator: ValidatorIndex(0),
 		signature: sign_approval(Sr25519Keyring::Alice, candidate_hash, 1),
 	};
 
@@ -640,7 +640,7 @@ fn rejects_approval_if_no_block_entry() {
 fn accepts_and_imports_approval_after_assignment() {
 	let block_hash = Hash::repeat_byte(0x01);
 	let candidate_hash = CandidateHash(Hash::repeat_byte(0xCC));
-	let validator_index = 0;
+	let validator_index = ValidatorIndex(0);
 
 	let candidate_index = 0;
 	let mut state = State {
@@ -649,7 +649,7 @@ fn accepts_and_imports_approval_after_assignment() {
 		})),
 		..some_state(StateConfig {
 			validators: vec![Sr25519Keyring::Alice, Sr25519Keyring::Bob, Sr25519Keyring::Charlie],
-			validator_groups: vec![vec![0, 1], vec![2]],
+			validator_groups: vec![vec![ValidatorIndex(0), ValidatorIndex(1)], vec![ValidatorIndex(2)]],
 			needed_approvals: 2,
 			..Default::default()
 		})
@@ -680,7 +680,7 @@ fn accepts_and_imports_approval_after_assignment() {
 		actions.get(0).unwrap(),
 		Action::WriteCandidateEntry(c_hash, c_entry) => {
 			assert_eq!(c_hash, &candidate_hash);
-			assert!(c_entry.approvals().get(validator_index as usize).unwrap());
+			assert!(c_entry.approvals().get(validator_index.0 as usize).unwrap());
 			assert!(!c_entry.approval_entry(&block_hash).unwrap().is_approved());
 		}
 	);
@@ -690,7 +690,7 @@ fn accepts_and_imports_approval_after_assignment() {
 fn second_approval_import_is_no_op() {
 	let block_hash = Hash::repeat_byte(0x01);
 	let candidate_hash = CandidateHash(Hash::repeat_byte(0xCC));
-	let validator_index = 0;
+	let validator_index = ValidatorIndex(0);
 
 	let candidate_index = 0;
 	let mut state = State {
@@ -699,7 +699,7 @@ fn second_approval_import_is_no_op() {
 		})),
 		..some_state(StateConfig {
 			validators: vec![Sr25519Keyring::Alice, Sr25519Keyring::Bob, Sr25519Keyring::Charlie],
-			validator_groups: vec![vec![0, 1], vec![2]],
+			validator_groups: vec![vec![ValidatorIndex(0), ValidatorIndex(1)], vec![ValidatorIndex(2)]],
 			needed_approvals: 2,
 			..Default::default()
 		})
@@ -734,8 +734,8 @@ fn second_approval_import_is_no_op() {
 fn check_and_apply_full_approval_sets_flag_and_bit() {
 	let block_hash = Hash::repeat_byte(0x01);
 	let candidate_hash = CandidateHash(Hash::repeat_byte(0xCC));
-	let validator_index_a = 0;
-	let validator_index_b = 1;
+	let validator_index_a = ValidatorIndex(0);
+	let validator_index_b = ValidatorIndex(1);
 
 	let mut state = State {
 		assignment_criteria: Box::new(MockAssignmentCriteria::check_only(|| {
@@ -743,7 +743,7 @@ fn check_and_apply_full_approval_sets_flag_and_bit() {
 		})),
 		..some_state(StateConfig {
 			validators: vec![Sr25519Keyring::Alice, Sr25519Keyring::Bob, Sr25519Keyring::Charlie],
-			validator_groups: vec![vec![0, 1], vec![2]],
+			validator_groups: vec![vec![ValidatorIndex(0), ValidatorIndex(1)], vec![ValidatorIndex(2)]],
 			needed_approvals: 2,
 			..Default::default()
 		})
@@ -795,8 +795,8 @@ fn check_and_apply_full_approval_sets_flag_and_bit() {
 fn check_and_apply_full_approval_does_not_load_cached_block_from_db() {
 	let block_hash = Hash::repeat_byte(0x01);
 	let candidate_hash = CandidateHash(Hash::repeat_byte(0xCC));
-	let validator_index_a = 0;
-	let validator_index_b = 1;
+	let validator_index_a = ValidatorIndex(0);
+	let validator_index_b = ValidatorIndex(1);
 
 	let mut state = State {
 		assignment_criteria: Box::new(MockAssignmentCriteria::check_only(|| {
@@ -804,7 +804,7 @@ fn check_and_apply_full_approval_does_not_load_cached_block_from_db() {
 		})),
 		..some_state(StateConfig {
 			validators: vec![Sr25519Keyring::Alice, Sr25519Keyring::Bob, Sr25519Keyring::Charlie],
-			validator_groups: vec![vec![0, 1], vec![2]],
+			validator_groups: vec![vec![ValidatorIndex(0), ValidatorIndex(1)], vec![ValidatorIndex(2)]],
 			needed_approvals: 2,
 			..Default::default()
 		})
@@ -867,7 +867,7 @@ fn assignment_triggered_by_all_with_less_than_supermajority() {
 					AssignmentCertKind::RelayVRFModulo { sample: 0 }
 				),
 				tranche: 1,
-				validator_index: 4,
+				validator_index: ValidatorIndex(4),
 				triggered: false,
 			}),
 			assignments: bitvec::bitvec![BitOrderLsb0, u8; 0; 4],
@@ -886,15 +886,15 @@ fn assignment_triggered_by_all_with_less_than_supermajority() {
 	candidate_entry
 		.approval_entry_mut(&block_hash)
 		.unwrap()
-		.import_assignment(0, 0, 0);
+		.import_assignment(0, ValidatorIndex(0), 0);
 
 	candidate_entry
 		.approval_entry_mut(&block_hash)
 		.unwrap()
-		.import_assignment(0, 1, 0);
+		.import_assignment(0, ValidatorIndex(1), 0);
 
-	candidate_entry.mark_approval(0);
-	candidate_entry.mark_approval(1);
+	candidate_entry.mark_approval(ValidatorIndex(0));
+	candidate_entry.mark_approval(ValidatorIndex(1));
 
 	let tranche_now = 1;
 	assert!(should_trigger_assignment(
@@ -918,7 +918,7 @@ fn assignment_not_triggered_by_all_with_supermajority() {
 					AssignmentCertKind::RelayVRFModulo { sample: 0 }
 				),
 				tranche: 1,
-				validator_index: 4,
+				validator_index: ValidatorIndex(4),
 				triggered: false,
 			}),
 			assignments: bitvec::bitvec![BitOrderLsb0, u8; 0; 4],
@@ -937,21 +937,21 @@ fn assignment_not_triggered_by_all_with_supermajority() {
 	candidate_entry
 		.approval_entry_mut(&block_hash)
 		.unwrap()
-		.import_assignment(0, 0, 0);
+		.import_assignment(0, ValidatorIndex(0), 0);
 
 	candidate_entry
 		.approval_entry_mut(&block_hash)
 		.unwrap()
-		.import_assignment(0, 1, 0);
+		.import_assignment(0, ValidatorIndex(1), 0);
 
 	candidate_entry
 		.approval_entry_mut(&block_hash)
 		.unwrap()
-		.import_assignment(0, 2, 0);
+		.import_assignment(0, ValidatorIndex(2), 0);
 
-	candidate_entry.mark_approval(0);
-	candidate_entry.mark_approval(1);
-	candidate_entry.mark_approval(2);
+	candidate_entry.mark_approval(ValidatorIndex(0));
+	candidate_entry.mark_approval(ValidatorIndex(1));
+	candidate_entry.mark_approval(ValidatorIndex(2));