introduce api versioning for min_backing votes

also enable it for rococo/versi for testing

node/core/backing/src/lib.rs

@@ -115,7 +115,7 @@ use statement_table::{
 	},
 	Config as TableConfig, Context as TableContextTrait, Table,
 };
-use util::runtime::RuntimeInfo;
+use util::{request_runtime_api_version, runtime::RuntimeInfo};
 
 mod error;
 
@@ -127,6 +127,9 @@ mod tests;
 
 const LOG_TARGET: &str = "parachain::candidate-backing";
 
+/// Used prior to runtime API version 6.
+const LEGACY_MIN_BACKING_VOTES: u32 = 2;
+
 /// PoV data to validate.
 enum PoVData {
 	/// Already available (from candidate selection).
@@ -998,9 +1001,19 @@ async fn construct_per_relay_parent_state<Context>(
 
 	let session_index =
 		try_runtime_api!(runtime_info.get_session_index_for_child(ctx.sender(), parent).await);
+	let runtime_api_version = try_runtime_api!(request_runtime_api_version(parent, ctx.sender())
+		.await
+		.await
+		.map_err(Error::RuntimeApiUnavailable)?);
+
 	let minimum_backing_votes =
-		runtime_info.get_min_backing_votes(ctx.sender(), session_index, parent).await;
-	// TODO: if this does not exist, fall back to the hardcoded 2 value.
+		if runtime_api_version >= RuntimeApiRequest::MINIMUM_BACKING_VOTES_RUNTIME_REQUIREMENT {
+			try_runtime_api!(
+				runtime_info.get_min_backing_votes(ctx.sender(), session_index, parent).await
+			)
+		} else {
+			LEGACY_MIN_BACKING_VOTES
+		};
 
 	let (validators, groups, cores) = futures::try_join!(
 		request_validators(parent, ctx.sender()).await,
@@ -1015,7 +1028,6 @@ async fn construct_per_relay_parent_state<Context>(
 	let validators: Vec<_> = try_runtime_api!(validators);
 	let (validator_groups, group_rotation_info) = try_runtime_api!(groups);
 	let cores = try_runtime_api!(cores);
-	let minimum_backing_votes = try_runtime_api!(minimum_backing_votes);
 
 	let signing_context = SigningContext { parent_hash: parent, session_index };
 	let validator =

node/core/backing/src/tests/mod.rs

@@ -262,6 +262,16 @@ async fn test_startup(virtual_overseer: &mut VirtualOverseer, test_state: &TestS
 		}
 	);
 
+	// Check that subsystem job issues a request for the runtime API version.
+	assert_matches!(
+		virtual_overseer.recv().await,
+		AllMessages::RuntimeApi(
+			RuntimeApiMessage::Request(parent, RuntimeApiRequest::Version(tx))
+		) if parent == test_state.relay_parent => {
+			tx.send(Ok(RuntimeApiRequest::MINIMUM_BACKING_VOTES_RUNTIME_REQUIREMENT)).unwrap();
+		}
+	);
+
 	// Check if subsystem job issues a request for the minimum backing votes.
 	// This may or may not happen, depending if the minimum backing votes is already cached in the
 	// RuntimeInfo.

node/core/backing/src/tests/prospective_parachains.rs

@@ -153,6 +153,16 @@ async fn activate_leaf(
 			}
 		);
 
+		// Check that subsystem job issues a request for the runtime API version.
+		assert_matches!(
+			virtual_overseer.recv().await,
+			AllMessages::RuntimeApi(
+				RuntimeApiMessage::Request(parent, RuntimeApiRequest::Version(tx))
+			) if parent == hash => {
+				tx.send(Ok(RuntimeApiRequest::MINIMUM_BACKING_VOTES_RUNTIME_REQUIREMENT)).unwrap();
+			}
+		);
+
 		// Check if subsystem job issues a request for the minimum backing votes.
 		// This may or may not happen, depending if the minimum backing votes is already cached in
 		// the `RuntimeInfo`.

node/core/runtime-api/src/lib.rs

@@ -455,9 +455,6 @@ where
 
 		Request::Authorities(sender) => query!(Authorities, authorities(), ver = 1, sender),
 		Request::Validators(sender) => query!(Validators, validators(), ver = 1, sender),
-		Request::MinimumBackingVotes(sender) =>
-			query!(MinimumBackingVotes, minimum_backing_votes(), ver = 1, sender),
-
 		Request::ValidatorGroups(sender) => {
 			query!(ValidatorGroups, validator_groups(), ver = 1, sender)
 		},
@@ -559,6 +556,12 @@ where
 			ver = Request::SUBMIT_REPORT_DISPUTE_LOST_RUNTIME_REQUIREMENT,
 			sender
 		),
+		Request::MinimumBackingVotes(sender) => query!(
+			MinimumBackingVotes,
+			minimum_backing_votes(),
+			ver = Request::MINIMUM_BACKING_VOTES_RUNTIME_REQUIREMENT,
+			sender
+		),
 
 		Request::StagingParaBackingState(para, sender) => {
 			query!(

node/primitives/src/lib.rs

@@ -659,6 +659,8 @@ pub fn maybe_compress_pov(pov: PoV) -> PoV {
 /// How many votes we need to consider a candidate backed.
 ///
 /// WARNING: This has to be kept in sync with the runtime check in the inclusion module.
+/// The min threshold has been added to the HostConfiguration and after the runtime API for querying
+/// it, `minimum_backing_votes`, is moved from vstaging to production, we can remove this.
 pub fn minimum_votes(n_validators: usize) -> usize {
 	std::cmp::min(2, n_validators)
 }

node/service/src/fake_runtime_api.rs

@@ -121,10 +121,6 @@ sp_api::impl_runtime_apis! {
 			unimplemented!()
 		}
 
-		fn minimum_backing_votes() -> u32 {
-			unimplemented!()
-		}
-
 		fn validator_groups() -> (Vec<Vec<ValidatorIndex>>, GroupRotationInfo<BlockNumber>) {
 			unimplemented!()
 		}

node/subsystem-types/src/messages.rs

@@ -721,6 +721,9 @@ impl RuntimeApiRequest {
 	/// `SubmitReportDisputeLost`
 	pub const SUBMIT_REPORT_DISPUTE_LOST_RUNTIME_REQUIREMENT: u32 = 5;
 
+	/// `MinimumBackingVotes`
+	pub const MINIMUM_BACKING_VOTES_RUNTIME_REQUIREMENT: u32 = 6;
+
 	/// Minimum version for backing state, required for async backing.
 	///
 	/// 99 for now, should be adjusted to VSTAGING/actual runtime version once released.

primitives/src/runtime_api.rs

@@ -240,8 +240,11 @@ sp_api::decl_runtime_apis! {
 			key_ownership_proof: vstaging::slashing::OpaqueKeyOwnershipProof,
 		) -> Option<()>;
 
+		/***** Staging *****/
+
 		/// Get the minimum number of backing votes for a parachain candidate.
-		/// TODO: bump api version here?
+		/// This is a staging method! Do not use on production runtimes!
+		#[api_version(6)]
 		fn minimum_backing_votes() -> u32;
 
 		/***** Asynchronous backing *****/

runtime/kusama/src/lib.rs

@@ -1894,10 +1894,6 @@ sp_api::impl_runtime_apis! {
 			parachains_runtime_api_impl::validators::<Runtime>()
 		}
 
-		fn minimum_backing_votes() -> u32 {
-			parachains_runtime_api_impl::minimum_backing_votes::<Runtime>()
-		}
-
 		fn validator_groups() -> (Vec<Vec<ValidatorIndex>>, GroupRotationInfo<BlockNumber>) {
 			parachains_runtime_api_impl::validator_groups::<Runtime>()
 		}

runtime/parachains/src/runtime_api_impl/v5.rs

@@ -38,12 +38,6 @@ pub fn validators<T: initializer::Config>() -> Vec<ValidatorId> {
 	<shared::Pallet<T>>::active_validator_keys()
 }
 
-/// Implementation of the `minimum_backing_votes` function of the runtime API.
-pub fn minimum_backing_votes<T: initializer::Config>() -> u32 {
-	let config = <configuration::Pallet<T>>::config();
-	config.minimum_backing_votes
-}
-
 /// Implementation for the `validator_groups` function of the runtime API.
 pub fn validator_groups<T: initializer::Config>(
 ) -> (Vec<Vec<ValidatorIndex>>, GroupRotationInfo<BlockNumberFor<T>>) {

runtime/parachains/src/runtime_api_impl/vstaging.rs

@@ -118,3 +118,9 @@ pub fn backing_state<T: initializer::Config>(
 pub fn async_backing_params<T: configuration::Config>() -> AsyncBackingParams {
 	<configuration::Pallet<T>>::config().async_backing_params
 }
+
+/// Implementation of the `minimum_backing_votes` function of the runtime API.
+pub fn minimum_backing_votes<T: initializer::Config>() -> u32 {
+	let config = <configuration::Pallet<T>>::config();
+	config.minimum_backing_votes
+}

runtime/polkadot/src/lib.rs

@@ -1697,10 +1697,6 @@ sp_api::impl_runtime_apis! {
 			parachains_runtime_api_impl::validators::<Runtime>()
 		}
 
-		fn minimum_backing_votes() -> u32 {
-			parachains_runtime_api_impl::minimum_backing_votes::<Runtime>()
-		}
-
 		fn validator_groups() -> (Vec<Vec<ValidatorIndex>>, GroupRotationInfo<BlockNumber>) {
 			parachains_runtime_api_impl::validator_groups::<Runtime>()
 		}

runtime/rococo/src/lib.rs

@@ -46,7 +46,9 @@ use runtime_parachains::{
 	inclusion::{AggregateMessageOrigin, UmpQueueId},
 	initializer as parachains_initializer, origin as parachains_origin, paras as parachains_paras,
 	paras_inherent as parachains_paras_inherent,
-	runtime_api_impl::v5 as parachains_runtime_api_impl,
+	runtime_api_impl::{
+		v5 as parachains_runtime_api_impl, vstaging as parachains_staging_runtime_api_impl,
+	},
 	scheduler as parachains_scheduler, session_info as parachains_session_info,
 	shared as parachains_shared,
 };
@@ -1715,15 +1717,12 @@ sp_api::impl_runtime_apis! {
 		}
 	}
 
+	#[api_version(6)]
 	impl primitives::runtime_api::ParachainHost<Block, Hash, BlockNumber> for Runtime {
 		fn validators() -> Vec<ValidatorId> {
 			parachains_runtime_api_impl::validators::<Runtime>()
 		}
 
-		fn minimum_backing_votes() -> u32 {
-			parachains_runtime_api_impl::minimum_backing_votes::<Runtime>()
-		}
-
 		fn validator_groups() -> (Vec<Vec<ValidatorIndex>>, GroupRotationInfo<BlockNumber>) {
 			parachains_runtime_api_impl::validator_groups::<Runtime>()
 		}
@@ -1849,6 +1848,10 @@ sp_api::impl_runtime_apis! {
 				key_ownership_proof,
 			)
 		}
+
+		fn minimum_backing_votes() -> u32 {
+			parachains_staging_runtime_api_impl::minimum_backing_votes::<Runtime>()
+		}
 	}
 
 	#[api_version(3)]

runtime/test-runtime/src/lib.rs

@@ -826,10 +826,6 @@ sp_api::impl_runtime_apis! {
 			runtime_impl::validators::<Runtime>()
 		}
 
-		fn minimum_backing_votes() -> u32 {
-			runtime_impl::minimum_backing_votes::<Runtime>()
-		}
-
 		fn validator_groups() -> (Vec<Vec<ValidatorIndex>>, GroupRotationInfo<BlockNumber>) {
 			runtime_impl::validator_groups::<Runtime>()
 		}

runtime/westend/src/lib.rs

@@ -1567,10 +1567,6 @@ sp_api::impl_runtime_apis! {
 			parachains_runtime_api_impl::validators::<Runtime>()
 		}
 
-		fn minimum_backing_votes() -> u32 {
-			parachains_runtime_api_impl::minimum_backing_votes::<Runtime>()
-		}
-
 		fn validator_groups() -> (Vec<Vec<ValidatorIndex>>, GroupRotationInfo<BlockNumber>) {
 			parachains_runtime_api_impl::validator_groups::<Runtime>()
 		}