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.
2026-06-12 20:31:13 +00:00 · 2021-02-26 18:58:07 +01:00
parent 241b1f12a7
commit 48409e5548
45 changed files with 2037 additions and 1523 deletions
@@ -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;
@@ -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)
 		});
 	}
@@ -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,
@@ -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(),
 			);

@@ -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
 	}

@@ -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));

 	let tranche_now = 1;
 	assert!(!should_trigger_assignment(
@@ -975,7 +975,7 @@ fn assignment_not_triggered_if_already_triggered() {
 					AssignmentCertKind::RelayVRFModulo { sample: 0 }
 				),
 				tranche: 1,
-				validator_index: 4,
+				validator_index: ValidatorIndex(4),
 				triggered: true,
 			}),
 			assignments: bitvec::bitvec![BitOrderLsb0, u8; 0; 4],
@@ -1012,7 +1012,7 @@ fn assignment_not_triggered_by_exact() {
 					AssignmentCertKind::RelayVRFModulo { sample: 0 }
 				),
 				tranche: 1,
-				validator_index: 4,
+				validator_index: ValidatorIndex(4),
 				triggered: false,
 			}),
 			assignments: bitvec::bitvec![BitOrderLsb0, u8; 0; 4],
@@ -1050,7 +1050,7 @@ fn assignment_not_triggered_more_than_maximum() {
 					AssignmentCertKind::RelayVRFModulo { sample: 0 }
 				),
 				tranche: maximum_broadcast + 1,
-				validator_index: 4,
+				validator_index: ValidatorIndex(4),
 				triggered: false,
 			}),
 			assignments: bitvec::bitvec![BitOrderLsb0, u8; 0; 4],
@@ -1093,7 +1093,7 @@ fn assignment_triggered_if_at_maximum() {
 					AssignmentCertKind::RelayVRFModulo { sample: 0 }
 				),
 				tranche: maximum_broadcast,
-				validator_index: 4,
+				validator_index: ValidatorIndex(4),
 				triggered: false,
 			}),
 			assignments: bitvec::bitvec![BitOrderLsb0, u8; 0; 4],
@@ -1136,7 +1136,7 @@ fn assignment_not_triggered_if_at_maximum_but_clock_is_before() {
 					AssignmentCertKind::RelayVRFModulo { sample: 0 }
 				),
 				tranche: maximum_broadcast,
-				validator_index: 4,
+				validator_index: ValidatorIndex(4),
 				triggered: false,
 			}),
 			assignments: bitvec::bitvec![BitOrderLsb0, u8; 0; 4],
@@ -1179,7 +1179,7 @@ fn assignment_not_triggered_if_at_maximum_but_clock_is_before_with_drift() {
 					AssignmentCertKind::RelayVRFModulo { sample: 0 }
 				),
 				tranche: maximum_broadcast,
-				validator_index: 4,
+				validator_index: ValidatorIndex(4),
 				triggered: false,
 			}),
 			assignments: bitvec::bitvec![BitOrderLsb0, u8; 0; 4],
@@ -1277,8 +1277,8 @@ fn block_not_approved_until_all_candidates_approved() {
 	let candidate_hash = CandidateHash(Hash::repeat_byte(0xCC));
 	let candidate_hash_2 = CandidateHash(Hash::repeat_byte(0xDD));

-	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(|| {
@@ -1286,7 +1286,7 @@ fn block_not_approved_until_all_candidates_approved() {
 		})),
 		..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()
 		})
@@ -1359,8 +1359,8 @@ fn candidate_approval_applied_to_all_blocks() {
 	let block_hash = Hash::repeat_byte(0x01);
 	let block_hash_2 = Hash::repeat_byte(0x02);
 	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 slot = Slot::from(1);
 	let session_index = 1;
@@ -1371,7 +1371,7 @@ fn candidate_approval_applied_to_all_blocks() {
 		})),
 		..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,
 			session_index,
 			slot,
@@ -1474,7 +1474,7 @@ fn approved_ancestor_all_approved() {
 		})),
 		..some_state(StateConfig {
 			validators: vec![Sr25519Keyring::Alice, Sr25519Keyring::Bob],
-			validator_groups: vec![vec![0], vec![1]],
+			validator_groups: vec![vec![ValidatorIndex(0)], vec![ValidatorIndex(1)]],
 			needed_approvals: 2,
 			session_index,
 			slot,
@@ -1556,7 +1556,7 @@ fn approved_ancestor_missing_approval() {
 		})),
 		..some_state(StateConfig {
 			validators: vec![Sr25519Keyring::Alice, Sr25519Keyring::Bob],
-			validator_groups: vec![vec![0], vec![1]],
+			validator_groups: vec![vec![ValidatorIndex(0)], vec![ValidatorIndex(1)]],
 			needed_approvals: 2,
 			session_index,
 			slot,
@@ -1633,7 +1633,7 @@ fn process_wakeup_trigger_assignment_launch_approval() {
 		})),
 		..some_state(StateConfig {
 			validators: vec![Sr25519Keyring::Alice, Sr25519Keyring::Bob],
-			validator_groups: vec![vec![0], vec![1]],
+			validator_groups: vec![vec![ValidatorIndex(0)], vec![ValidatorIndex(1)]],
 			needed_approvals: 2,
 			session_index,
 			slot,
@@ -1660,7 +1660,7 @@ fn process_wakeup_trigger_assignment_launch_approval() {
 				AssignmentCertKind::RelayVRFModulo { sample: 0 }
 			),
 			tranche: 0,
-			validator_index: 0,
+			validator_index: ValidatorIndex(0),
 			triggered: false,
 		}.into());

@@ -1720,7 +1720,7 @@ fn process_wakeup_schedules_wakeup() {
 		})),
 		..some_state(StateConfig {
 			validators: vec![Sr25519Keyring::Alice, Sr25519Keyring::Bob],
-			validator_groups: vec![vec![0], vec![1]],
+			validator_groups: vec![vec![ValidatorIndex(0)], vec![ValidatorIndex(1)]],
 			needed_approvals: 2,
 			session_index,
 			slot,
@@ -1738,7 +1738,7 @@ fn process_wakeup_schedules_wakeup() {
 				AssignmentCertKind::RelayVRFModulo { sample: 0 }
 			),
 			tranche: 10,
-			validator_index: 0,
+			validator_index: ValidatorIndex(0),
 			triggered: false,
 		}.into());

@@ -968,7 +968,7 @@ fn process_message(
 		AvailabilityStoreMessage::QueryChunkAvailability(candidate, validator_index, tx) => {
 			let a = load_meta(&subsystem.db, &candidate)?
 				.map_or(false, |m|
-					*m.chunks_stored.get(validator_index as usize).as_deref().unwrap_or(&false)
+					*m.chunks_stored.get(validator_index.0 as usize).as_deref().unwrap_or(&false)
 				);
 			let _ = tx.send(a);
 		}
@@ -1034,10 +1034,10 @@ fn store_chunk(
 		None => return Ok(false), // we weren't informed of this candidate by import events.
 	};

-	match meta.chunks_stored.get(chunk.index as usize).map(|b| *b) {
+	match meta.chunks_stored.get(chunk.index.0 as usize).map(|b| *b) {
 		Some(true) => return Ok(true), // already stored.
 		Some(false) => {
-			meta.chunks_stored.set(chunk.index as usize, true);
+			meta.chunks_stored.set(chunk.index.0 as usize, true);

 			write_chunk(&mut tx, &candidate_hash, chunk.index, &chunk);
 			write_meta(&mut tx, &candidate_hash, &meta);
@@ -1090,7 +1090,7 @@ fn store_available_data(
 		.map(|(index, (chunk, proof))| ErasureChunk {
 			chunk: chunk.clone(),
 			proof,
-			index: index as u32,
+			index: ValidatorIndex(index as u32),
 		});

 	for chunk in erasure_chunks {
@@ -1142,7 +1142,7 @@ fn prune_all(db: &Arc<dyn KeyValueDB>, clock: &dyn Clock) -> Result<(), Error> {
 			// delete chunks.
 			for (i, b) in meta.chunks_stored.iter().enumerate() {
 				if *b {
-					delete_chunk(&mut tx, &candidate_hash, i as _);
+					delete_chunk(&mut tx, &candidate_hash, ValidatorIndex(i as _));
 				}
 			}

@@ -260,7 +260,7 @@ fn runtime_api_error_does_not_stop_the_subsystem() {
 		// but that's fine, we're still alive
 		let (tx, rx) = oneshot::channel();
 		let candidate_hash = CandidateHash(Hash::repeat_byte(33));
-		let validator_index = 5;
+		let validator_index = ValidatorIndex(5);
 		let query_chunk = AvailabilityStoreMessage::QueryChunk(
 			candidate_hash,
 			validator_index,
@@ -281,7 +281,7 @@ fn store_chunk_works() {
 		let TestHarness { mut virtual_overseer } = test_harness;
 		let relay_parent = Hash::repeat_byte(32);
 		let candidate_hash = CandidateHash(Hash::repeat_byte(33));
-		let validator_index = 5;
+		let validator_index = ValidatorIndex(5);
 		let n_validators = 10;

 		let chunk = ErasureChunk {
@@ -333,7 +333,7 @@ fn store_chunk_does_nothing_if_no_entry_already() {
 		let TestHarness { mut virtual_overseer } = test_harness;
 		let relay_parent = Hash::repeat_byte(32);
 		let candidate_hash = CandidateHash(Hash::repeat_byte(33));
-		let validator_index = 5;
+		let validator_index = ValidatorIndex(5);

 		let chunk = ErasureChunk {
 			chunk: vec![1, 2, 3],
@@ -372,7 +372,7 @@ fn query_chunk_checks_meta() {
 	test_harness(TestState::default(), store.clone(), |test_harness| async move {
 		let TestHarness { mut virtual_overseer } = test_harness;
 		let candidate_hash = CandidateHash(Hash::repeat_byte(33));
-		let validator_index = 5;
+		let validator_index = ValidatorIndex(5);
 		let n_validators = 10;

 		// Ensure an entry already exists. In reality this would come from watching
@@ -382,7 +382,7 @@ fn query_chunk_checks_meta() {
 				data_available: false,
 				chunks_stored: {
 					let mut v = bitvec::bitvec![BitOrderLsb0, u8; 0; n_validators];
-					v.set(validator_index as usize, true);
+					v.set(validator_index.0 as usize, true);
 					v
 				},
 				state: State::Unavailable(BETimestamp(0)),
@@ -402,7 +402,7 @@ fn query_chunk_checks_meta() {
 		let (tx, rx) = oneshot::channel();
 		let query_chunk = AvailabilityStoreMessage::QueryChunkAvailability(
 			candidate_hash,
-			validator_index + 1,
+			ValidatorIndex(validator_index.0 + 1),
 			tx,
 		);

@@ -418,7 +418,7 @@ fn store_block_works() {
 	test_harness(test_state.clone(), store.clone(), |test_harness| async move {
 		let TestHarness { mut virtual_overseer } = test_harness;
 		let candidate_hash = CandidateHash(Hash::repeat_byte(1));
-		let validator_index = 5;
+		let validator_index = ValidatorIndex(5);
 		let n_validators = 10;

 		let pov = PoV {
@@ -455,7 +455,7 @@ fn store_block_works() {
 		let branch = branches.nth(5).unwrap();
 		let expected_chunk = ErasureChunk {
 			chunk: branch.1.to_vec(),
-			index: 5,
+			index: ValidatorIndex(5),
 			proof: branch.0,
 		};

@@ -497,10 +497,10 @@ fn store_pov_and_query_chunk_works() {

 		assert_eq!(rx.await.unwrap(), Ok(()));

-		for validator_index in 0..n_validators {
-			let chunk = query_chunk(&mut virtual_overseer, candidate_hash, validator_index).await.unwrap();
+		for i in 0..n_validators {
+			let chunk = query_chunk(&mut virtual_overseer, candidate_hash, ValidatorIndex(i as _)).await.unwrap();

-			assert_eq!(chunk.chunk, chunks_expected[validator_index as usize]);
+			assert_eq!(chunk.chunk, chunks_expected[i as usize]);
 		}
 	});
 }
@@ -842,7 +842,7 @@ async fn query_available_data(
 async fn query_chunk(
 	virtual_overseer: &mut test_helpers::TestSubsystemContextHandle<AvailabilityStoreMessage>,
 	candidate_hash: CandidateHash,
-	index: u32,
+	index: ValidatorIndex,
 ) -> Option<ErasureChunk> {
 	let (tx, rx) = oneshot::channel();

@@ -859,7 +859,7 @@ async fn query_all_chunks(
 	expect_present: bool,
 ) -> bool {
 	for i in 0..n_validators {
-		if query_chunk(virtual_overseer, candidate_hash, i).await.is_some() != expect_present {
+		if query_chunk(virtual_overseer, candidate_hash, ValidatorIndex(i)).await.is_some() != expect_present {
 			return false
 		}
 	}
@@ -899,7 +899,7 @@ impl CandidateBackingJob {

 	#[tracing::instrument(level = "trace", skip(self), fields(subsystem = LOG_TARGET))]
 	fn check_statement_signature(&self, statement: &SignedFullStatement) -> Result<(), Error> {
-		let idx = statement.validator_index() as usize;
+		let idx = statement.validator_index().0 as usize;

 		if self.table_context.validators.len() > idx {
 			statement.check_signature(
@@ -1282,7 +1282,8 @@ mod tests {

 			let validator_public = validator_pubkeys(&validators);

-			let validator_groups = vec![vec![2, 0, 3, 5], vec![1], vec![4]];
+			let validator_groups = vec![vec![2, 0, 3, 5], vec![1], vec![4]]
+				.into_iter().map(|g| g.into_iter().map(ValidatorIndex).collect()).collect();
 			let group_rotation_info = GroupRotationInfo {
 				session_start_block: 0,
 				group_rotation_frequency: 100,
@@ -1599,7 +1600,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Seconded(candidate_a.clone()),
 				&test_state.signing_context,
-				2,
+				ValidatorIndex(2),
 				&public2.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -1607,7 +1608,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Valid(candidate_a_hash),
 				&test_state.signing_context,
-				5,
+				ValidatorIndex(5),
 				&public1.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -1741,7 +1742,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Seconded(candidate_a.clone()),
 				&test_state.signing_context,
-				2,
+				ValidatorIndex(2),
 				&public2.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -1749,7 +1750,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Valid(candidate_a_hash),
 				&test_state.signing_context,
-				5,
+				ValidatorIndex(5),
 				&public1.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -1757,7 +1758,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Valid(candidate_a_hash),
 				&test_state.signing_context,
-				3,
+				ValidatorIndex(3),
 				&public3.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -1894,7 +1895,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Seconded(candidate_a.clone()),
 				&test_state.signing_context,
-				2,
+				ValidatorIndex(2),
 				&public2.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -1902,7 +1903,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Invalid(candidate_a_hash),
 				&test_state.signing_context,
-				2,
+				ValidatorIndex(2),
 				&public2.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -1910,7 +1911,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Invalid(candidate_a_hash),
 				&test_state.signing_context,
-				0,
+				ValidatorIndex(0),
 				&public0.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -2002,7 +2003,7 @@ mod tests {
 						validator_index,
 						s1,
 						&test_state.signing_context,
-						&test_state.validator_public[validator_index as usize],
+						&test_state.validator_public[validator_index.0 as usize],
 					).expect("signature must be valid");

 					SignedFullStatement::new(
@@ -2010,7 +2011,7 @@ mod tests {
 						validator_index,
 						s2,
 						&test_state.signing_context,
-						&test_state.validator_public[validator_index as usize],
+						&test_state.validator_public[validator_index.0 as usize],
 					).expect("signature must be valid");
 				}
 			);
@@ -2042,7 +2043,7 @@ mod tests {
 						validator_index,
 						s1,
 						&test_state.signing_context,
-						&test_state.validator_public[validator_index as usize],
+						&test_state.validator_public[validator_index.0 as usize],
 					).expect("signature must be valid");

 					SignedFullStatement::new(
@@ -2050,7 +2051,7 @@ mod tests {
 						validator_index,
 						s2,
 						&test_state.signing_context,
-						&test_state.validator_public[validator_index as usize],
+						&test_state.validator_public[validator_index.0 as usize],
 					).expect("signature must be valid");
 				}
 			);
@@ -2223,7 +2224,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Seconded(candidate.clone()),
 				&test_state.signing_context,
-				2,
+				ValidatorIndex(2),
 				&validator2.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -2361,7 +2362,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Seconded(candidate.clone()),
 				&test_state.signing_context,
-				2,
+				ValidatorIndex(2),
 				&public2.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -2503,7 +2504,7 @@ mod tests {
 				&test_state.keystore,
 				Statement::Seconded(candidate_a.clone()),
 				&test_state.signing_context,
-				2,
+				ValidatorIndex(2),
 				&public2.into(),
 			).await.ok().flatten().expect("should be signed");

@@ -2542,7 +2543,7 @@ mod tests {
 		let validator_public = validator_pubkeys(&validators);
 		let validator_groups = {
 			let mut validator_groups = HashMap::new();
-			validator_groups.insert(para_id, vec![0, 1, 2, 3, 4, 5]);
+			validator_groups.insert(para_id, vec![0, 1, 2, 3, 4, 5].into_iter().map(ValidatorIndex).collect());
 			validator_groups
 		};

@@ -2567,9 +2568,9 @@ mod tests {
 		let attested = TableAttestedCandidate {
 			candidate: Default::default(),
 			validity_votes: vec![
-				(5, fake_attestation(5)),
-				(3, fake_attestation(3)),
-				(1, fake_attestation(1)),
+				(ValidatorIndex(5), fake_attestation(5)),
+				(ValidatorIndex(3), fake_attestation(3)),
+				(ValidatorIndex(1), fake_attestation(1)),
 			],
 			group_id: para_id,
 		};
@@ -333,7 +333,7 @@ mod tests {
 		block_on(async move {
 			let (mut sender, mut receiver) = mpsc::channel(10);
 			let relay_parent = Hash::default();
-			let validator_index = 1u32;
+			let validator_index = ValidatorIndex(1u32);

 			let future = construct_availability_bitfield(
 				relay_parent,
@@ -501,7 +501,7 @@ fn bitfields_indicate_availability(
 	let availability_len = availability.len();

 	for bitfield in bitfields {
-		let validator_idx = bitfield.validator_index() as usize;
+		let validator_idx = bitfield.validator_index().0 as usize;
 		match availability.get_mut(validator_idx) {
 			None => {
 				// in principle, this function might return a `Result<bool, Error>` so that we can more clearly express this error condition
@@ -78,9 +78,9 @@ mod select_availability_bitfields {
 		// we pass in three bitfields with two validators
 		// this helps us check the postcondition that we get two bitfields back, for which the validators differ
 		let bitfields = vec![
-			block_on(signed_bitfield(&keystore, bitvec.clone(), 0)),
-			block_on(signed_bitfield(&keystore, bitvec.clone(), 1)),
-			block_on(signed_bitfield(&keystore, bitvec, 1)),
+			block_on(signed_bitfield(&keystore, bitvec.clone(), ValidatorIndex(0))),
+			block_on(signed_bitfield(&keystore, bitvec.clone(), ValidatorIndex(1))),
+			block_on(signed_bitfield(&keystore, bitvec, ValidatorIndex(1))),
 		];

 		let mut selected_bitfields = select_availability_bitfields(&cores, &bitfields);
@@ -116,9 +116,9 @@ mod select_availability_bitfields {
 		];

 		let bitfields = vec![
-			block_on(signed_bitfield(&keystore, bitvec0, 0)),
-			block_on(signed_bitfield(&keystore, bitvec1, 1)),
-			block_on(signed_bitfield(&keystore, bitvec2.clone(), 2)),
+			block_on(signed_bitfield(&keystore, bitvec0, ValidatorIndex(0))),
+			block_on(signed_bitfield(&keystore, bitvec1, ValidatorIndex(1))),
+			block_on(signed_bitfield(&keystore, bitvec2.clone(), ValidatorIndex(2))),
 		];

 		let selected_bitfields = select_availability_bitfields(&cores, &bitfields);
@@ -140,8 +140,8 @@ mod select_availability_bitfields {
 		let cores = vec![occupied_core(0), occupied_core(1)];

 		let bitfields = vec![
-			block_on(signed_bitfield(&keystore, bitvec, 1)),
-			block_on(signed_bitfield(&keystore, bitvec1.clone(), 1)),
+			block_on(signed_bitfield(&keystore, bitvec, ValidatorIndex(1))),
+			block_on(signed_bitfield(&keystore, bitvec1.clone(), ValidatorIndex(1))),
 		];

 		let selected_bitfields = select_availability_bitfields(&cores, &bitfields);
@@ -174,11 +174,11 @@ mod select_availability_bitfields {
 		// these are out of order but will be selected in order. The better
 		// bitfield for 3 will be selected.
 		let bitfields = vec![
-			block_on(signed_bitfield(&keystore, bitvec2.clone(), 3)),
-			block_on(signed_bitfield(&keystore, bitvec3.clone(), 3)),
-			block_on(signed_bitfield(&keystore, bitvec0.clone(), 0)),
-			block_on(signed_bitfield(&keystore, bitvec2.clone(), 2)),
-			block_on(signed_bitfield(&keystore, bitvec1.clone(), 1)),
+			block_on(signed_bitfield(&keystore, bitvec2.clone(), ValidatorIndex(3))),
+			block_on(signed_bitfield(&keystore, bitvec3.clone(), ValidatorIndex(3))),
+			block_on(signed_bitfield(&keystore, bitvec0.clone(), ValidatorIndex(0))),
+			block_on(signed_bitfield(&keystore, bitvec2.clone(), ValidatorIndex(2))),
+			block_on(signed_bitfield(&keystore, bitvec1.clone(), ValidatorIndex(1))),
 		];

 		let selected_bitfields = select_availability_bitfields(&cores, &bitfields);