Handle missing group membership better.

node/network/availability-distribution/src/pov_requester/mod.rs

@@ -32,10 +32,7 @@ use polkadot_subsystem::{
 	ActiveLeavesUpdate, SubsystemContext, messages::{AllMessages, NetworkBridgeMessage, IfDisconnected}
 };
 
-use crate::{
-	runtime::Runtime,
-	error::{Error, log_error},
-};
+use crate::{error::{Error, log_error}, runtime::{Runtime, ValidatorInfo}};
 
 /// Number of sessions we want to keep in the LRU.
 const NUM_SESSIONS: usize = 2;
@@ -216,13 +213,17 @@ where
 	Context: SubsystemContext,
 {
 	let info = runtime.get_session_info_by_index(ctx, parent, session).await?;
-	if let Some(validator_info) = &info.validator_info {
-		let indeces = info.session_info.validator_groups.get(validator_info.our_group.0 as usize)
+	if let ValidatorInfo {
+            our_index: Some(our_index),
+            our_group: Some(our_group)
+        } = &info.validator_info {
+
+		let indeces = info.session_info.validator_groups.get(our_group.0 as usize)
 			.expect("Our group got retrieved from that session info, it must exist. qed.")
 			.clone();
 		Ok(Some(
 			indeces.into_iter()
-			   .filter(|i| *i != validator_info.our_index)
+			   .filter(|i| *i != *our_index)
 			   .map(|i| info.session_info.discovery_keys[i.0 as usize].clone())
 			   .collect()
 	   ))

node/network/availability-distribution/src/requester/fetch_task/mod.rs

@@ -138,7 +138,7 @@ impl FetchTaskConfig {
 		let live_in = vec![leaf].into_iter().collect();
 
 		// Don't run tasks for our backing group:
-		if session_info.our_group == core.group_responsible {
+		if session_info.our_group == Some(core.group_responsible) {
 			return FetchTaskConfig {
 				live_in,
 				prepared_running: None,

node/network/availability-distribution/src/runtime.rs

@@ -55,17 +55,17 @@ pub struct ExtendedSessionInfo {
 	/// Actual session info as fetched from the runtime.
 	pub session_info: SessionInfo,
 	/// Contains useful information about ourselves, in case this node is a validator.
-	pub validator_info: Option<ValidatorInfo>,
+	pub validator_info: ValidatorInfo,
 }
 
 /// Information about ourself, in case we are an `Authority`.
 ///
 /// This data is derived from the `SessionInfo` and our key as found in the keystore.
 pub struct ValidatorInfo {
-	/// The index this very validator has in `SessionInfo` vectors.
-	pub our_index: ValidatorIndex,
-	/// The group we belong to.
-	pub our_group: GroupIndex,
+	/// The index this very validator has in `SessionInfo` vectors, if any.
+	pub our_index: Option<ValidatorIndex>,
+	/// The group we belong to, if any.
+	pub our_group: Option<GroupIndex>,
 }
 
 impl Runtime {
@@ -155,7 +155,7 @@ impl Runtime {
 	async fn get_validator_info(
 		&self,
 		session_info: &SessionInfo,
-	) -> Result<Option<ValidatorInfo>, Error>
+	) -> Result<ValidatorInfo, Error>
 	{
 		if let Some(our_index) = self.get_our_index(&session_info.validators).await {
 			// Get our group index:
@@ -172,19 +172,13 @@ impl Runtime {
 					})
 				}
 			);
-			debug_assert!(
-				our_group.is_some() || session_info.validator_groups.is_empty(),
-				"Groups are initialized but validator could not be found in any"
-			);
-			if let Some(our_group) = our_group {
-				let info = ValidatorInfo {
-					our_index,
-					our_group,
-				};
-				return Ok(Some(info))
-			}
+			let info = ValidatorInfo {
+				our_index: Some(our_index),
+				our_group,
+			};
+			return Ok(info)
 		}
-		return	Ok(None)
+		return Ok(ValidatorInfo { our_index: None, our_group: None })
 	}
 
 	/// Get our `ValidatorIndex`.

node/network/availability-distribution/src/session_cache.rs

@@ -81,7 +81,9 @@ pub struct SessionInfo {
 
 	/// Remember to which group we belong, so we won't start fetching chunks for candidates with
 	/// our group being responsible. (We should have that chunk already.)
-	pub our_group: GroupIndex,
+	///
+	/// `None`, if we are not in fact part of any group.
+	pub our_group: Option<GroupIndex>,
 }
 
 /// Report of bad validators.
@@ -246,10 +248,6 @@ impl SessionCache {
 					})
 				}
 			);
-			debug_assert!(
-				our_group.is_some() || validator_groups.is_empty(),
-				"Groups are initialized but validator could not be found in any"
-			);
 
 			// Shuffle validators in groups:
 			let mut rng = thread_rng();
@@ -271,15 +269,13 @@ impl SessionCache {
 				})
 				.collect();
 
-			if let Some(our_group) = our_group {
-				let info = SessionInfo {
-					validator_groups,
-					our_index,
-					session_index,
-					our_group,
-				};
-				return Ok(Some(info))
-			}
+			let info = SessionInfo {
+				validator_groups,
+				our_index,
+				session_index,
+				our_group,
+			};
+			return Ok(Some(info))
 		}
 		return Ok(None)
 	}