Disabled validators runtime API (#1257)

Exposes disabled validators list via a runtime API.

---------

Co-authored-by: ordian <noreply@reusable.software>
Co-authored-by: ordian <write@reusable.software>

polkadot/node/subsystem-types/src/messages.rs

@@ -695,6 +695,8 @@ pub enum RuntimeApiRequest {
 	),
 	/// Get the minimum required backing votes.
 	MinimumBackingVotes(SessionIndex, RuntimeApiSender<u32>),
+	/// Returns all disabled validators at a given block height.
+	DisabledValidators(RuntimeApiSender<Vec<ValidatorIndex>>),
 	/// Get the backing state of the given para.
 	ParaBackingState(ParaId, RuntimeApiSender<Option<async_backing::BackingState>>),
 	/// Get candidate's acceptance limitations for asynchronous backing for a relay parent.
@@ -726,6 +728,9 @@ impl RuntimeApiRequest {
 
 	/// Minimum version to enable asynchronous backing: `AsyncBackingParams` and `ParaBackingState`.
 	pub const ASYNC_BACKING_STATE_RUNTIME_REQUIREMENT: u32 = 7;
+
+	/// `DisabledValidators`
+	pub const DISABLED_VALIDATORS_RUNTIME_REQUIREMENT: u32 = 8;
 }
 
 /// A message to the Runtime API subsystem.

polkadot/node/subsystem-types/src/runtime_client.rs

@@ -255,6 +255,10 @@ pub trait RuntimeApiSubsystemClient {
 		at: Hash,
 		para_id: Id,
 	) -> Result<Option<async_backing::BackingState>, ApiError>;
+
+	// === v8 ===
+	/// Gets the disabled validators at a specific block height
+	async fn disabled_validators(&self, at: Hash) -> Result<Vec<ValidatorIndex>, ApiError>;
 }
 
 /// Default implementation of [`RuntimeApiSubsystemClient`] using the client.
@@ -497,11 +501,14 @@ where
 		self.client.runtime_api().para_backing_state(at, para_id)
 	}
 
-	/// Returns candidate's acceptance limitations for asynchronous backing for a relay parent.
 	async fn async_backing_params(
 		&self,
 		at: Hash,
 	) -> Result<async_backing::AsyncBackingParams, ApiError> {
 		self.client.runtime_api().async_backing_params(at)
 	}
+
+	async fn disabled_validators(&self, at: Hash) -> Result<Vec<ValidatorIndex>, ApiError> {
+		self.client.runtime_api().disabled_validators(at)
+	}
 }