Alter statement table to allow multiple seconded messages per validator

node/core/backing/src/lib.rs

@@ -111,7 +111,7 @@ use statement_table::{
 		SignedStatement as TableSignedStatement, Statement as TableStatement,
 		Summary as TableSummary,
 	},
-	Context as TableContextTrait, Table,
+	Config as TableConfig, Context as TableContextTrait, Table,
 };
 
 mod error;
@@ -1061,6 +1061,12 @@ async fn construct_per_relay_parent_state<Context>(
 	}
 
 	let table_context = TableContext { groups, validators, validator };
+	let table_config = TableConfig {
+		allow_multiple_seconded: match mode {
+			ProspectiveParachainsMode::Enabled => true,
+			ProspectiveParachainsMode::Disabled => false,
+		},
+	};
 
 	// TODO [now]: I've removed the `required_collator` more broadly,
 	// because it's not used in practice and was intended for parathreads.
@@ -1075,7 +1081,7 @@ async fn construct_per_relay_parent_state<Context>(
 		session_index,
 		assignment,
 		backed: HashSet::new(),
-		table: Table::default(),
+		table: Table::new(table_config),
 		table_context,
 		issued_statements: HashSet::new(),
 		awaiting_validation: HashSet::new(),
@@ -1544,10 +1550,6 @@ async fn import_statement<Context>(
 
 	let stmt = primitive_statement_to_table(statement);
 
-	// TODO [now]: we violate the pre-existing checks that each validator may
-	// only second one candidate.
-	//
-	// We will need to address this so we don't get errors incorrectly.
 	let summary = rp_state.table.import_statement(&rp_state.table_context, stmt);
 
 	if let Some(attested) = summary

statement-table/src/generic.rs

@@ -61,6 +61,14 @@ pub trait Context {
 	fn requisite_votes(&self, group: &Self::GroupId) -> usize;
 }
 
+/// Table configuration.
+pub struct Config {
+	/// When this is true, the table will allow multiple seconded candidates
+	/// per authority. This flag means that higher-level code is responsible for
+	/// bounding the number of candidates.
+	pub allow_multiple_seconded: bool,
+}
+
 /// Statements circulated among peers.
 #[derive(PartialEq, Eq, Debug, Clone, Encode, Decode)]
 pub enum Statement<Candidate, Digest> {
@@ -270,12 +278,12 @@ impl<Ctx: Context> CandidateData<Ctx> {
 
 // authority metadata
 struct AuthorityData<Ctx: Context> {
-	proposal: Option<(Ctx::Digest, Ctx::Signature)>,
+	proposals: Vec<(Ctx::Digest, Ctx::Signature)>,
 }
 
 impl<Ctx: Context> Default for AuthorityData<Ctx> {
 	fn default() -> Self {
-		AuthorityData { proposal: None }
+		AuthorityData { proposals: Vec::new() }
 	}
 }
 
@@ -290,19 +298,20 @@ pub struct Table<Ctx: Context> {
 	authority_data: HashMap<Ctx::AuthorityId, AuthorityData<Ctx>>,
 	detected_misbehavior: HashMap<Ctx::AuthorityId, Vec<MisbehaviorFor<Ctx>>>,
 	candidate_votes: HashMap<Ctx::Digest, CandidateData<Ctx>>,
+	config: Config,
 }
 
-impl<Ctx: Context> Default for Table<Ctx> {
-	fn default() -> Self {
+impl<Ctx: Context> Table<Ctx> {
+	/// Create a new `Table` from a `Config`.
+	pub fn new(config: Config) -> Self {
 		Table {
-			authority_data: HashMap::new(),
-			detected_misbehavior: HashMap::new(),
-			candidate_votes: HashMap::new(),
+			authority_data: HashMap::default(),
+			detected_misbehavior: HashMap::default(),
+			candidate_votes: HashMap::default(),
+			config,
 		}
 	}
-}
 
-impl<Ctx: Context> Table<Ctx> {
 	/// Get the attested candidate for `digest`.
 	///
 	/// Returns `Some(_)` if the candidate exists and is includable.
@@ -393,7 +402,9 @@ impl<Ctx: Context> Table<Ctx> {
 				// note misbehavior.
 				let existing = occ.get_mut();
 
-				if let Some((ref old_digest, ref old_sig)) = existing.proposal {
+				if !self.config.allow_multiple_seconded && existing.proposals.len() == 1 {
+					let &(ref old_digest, ref old_sig) = &existing.proposals[0];
+
 					if old_digest != &digest {
 						const EXISTENCE_PROOF: &str =
 							"when proposal first received from authority, candidate \
@@ -413,15 +424,17 @@ impl<Ctx: Context> Table<Ctx> {
 						}))
 					}
 
+					false
+				} else if self.config.allow_multiple_seconded && existing.proposals.iter().find(|(ref od, _)| od == &digest).is_some() {
 					false
 				} else {
-					existing.proposal = Some((digest.clone(), signature.clone()));
+					existing.proposals.push((digest.clone(), signature.clone()));
 					true
 				}
 			},
 			Entry::Vacant(vacant) => {
 				vacant
-					.insert(AuthorityData { proposal: Some((digest.clone(), signature.clone())) });
+					.insert(AuthorityData { proposals: vec![(digest.clone(), signature.clone())] });
 				true
 			},
 		};
@@ -571,8 +584,16 @@ mod tests {
 	use super::*;
 	use std::collections::HashMap;
 
-	fn create<Candidate: Context>() -> Table<Candidate> {
-		Table::default()
+	fn create_single_seconded<Candidate: Context>() -> Table<Candidate> {
+		Table::new(Config {
+			allow_multiple_seconded: false,
+		})
+	}
+
+	fn create_many_seconded<Candidate: Context>() -> Table<Candidate> {
+		Table::new(Config {
+			allow_multiple_seconded: true,
+		})
 	}
 
 	#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
@@ -630,7 +651,7 @@ mod tests {
 	}
 
 	#[test]
-	fn submitting_two_candidates_is_misbehavior() {
+	fn submitting_two_candidates_can_be_misbehavior() {
 		let context = TestContext {
 			authorities: {
 				let mut map = HashMap::new();
@@ -639,7 +660,7 @@ mod tests {
 			},
 		};
 
-		let mut table = create();
+		let mut table = create_single_seconded();
 		let statement_a = SignedStatement {
 			statement: Statement::Seconded(Candidate(2, 100)),
 			signature: Signature(1),
@@ -665,6 +686,36 @@ mod tests {
 		);
 	}
 
+	#[test]
+	fn submitting_two_candidates_can_be_allowed() {
+		let context = TestContext {
+			authorities: {
+				let mut map = HashMap::new();
+				map.insert(AuthorityId(1), GroupId(2));
+				map
+			},
+		};
+
+		let mut table = create_many_seconded();
+		let statement_a = SignedStatement {
+			statement: Statement::Seconded(Candidate(2, 100)),
+			signature: Signature(1),
+			sender: AuthorityId(1),
+		};
+
+		let statement_b = SignedStatement {
+			statement: Statement::Seconded(Candidate(2, 999)),
+			signature: Signature(1),
+			sender: AuthorityId(1),
+		};
+
+		table.import_statement(&context, statement_a);
+		assert!(!table.detected_misbehavior.contains_key(&AuthorityId(1)));
+
+		table.import_statement(&context, statement_b);
+		assert!(!table.detected_misbehavior.contains_key(&AuthorityId(1)));
+	}
+
 	#[test]
 	fn submitting_candidate_from_wrong_group_is_misbehavior() {
 		let context = TestContext {
@@ -675,7 +726,7 @@ mod tests {
 			},
 		};
 
-		let mut table = create();
+		let mut table = create_single_seconded();
 		let statement = SignedStatement {
 			statement: Statement::Seconded(Candidate(2, 100)),
 			signature: Signature(1),
@@ -707,7 +758,7 @@ mod tests {
 			},
 		};
 
-		let mut table = create();
+		let mut table = create_single_seconded();
 
 		let candidate_a = SignedStatement {
 			statement: Statement::Seconded(Candidate(2, 100)),
@@ -751,7 +802,7 @@ mod tests {
 			},
 		};
 
-		let mut table = create();
+		let mut table = create_single_seconded();
 		let statement = SignedStatement {
 			statement: Statement::Seconded(Candidate(2, 100)),
 			signature: Signature(1),
@@ -781,7 +832,7 @@ mod tests {
 			},
 		};
 
-		let mut table = create();
+		let mut table = create_single_seconded();
 		let statement = SignedStatement {
 			statement: Statement::Seconded(Candidate(2, 100)),
 			signature: Signature(1),
@@ -849,7 +900,7 @@ mod tests {
 		};
 
 		// have 2/3 validity guarantors note validity.
-		let mut table = create();
+		let mut table = create_single_seconded();
 		let statement = SignedStatement {
 			statement: Statement::Seconded(Candidate(2, 100)),
 			signature: Signature(1),
@@ -883,7 +934,7 @@ mod tests {
 			},
 		};
 
-		let mut table = create();
+		let mut table = create_single_seconded();
 		let statement = SignedStatement {
 			statement: Statement::Seconded(Candidate(2, 100)),
 			signature: Signature(1),
@@ -910,7 +961,7 @@ mod tests {
 			},
 		};
 
-		let mut table = create();
+		let mut table = create_single_seconded();
 		let statement = SignedStatement {
 			statement: Statement::Seconded(Candidate(2, 100)),
 			signature: Signature(1),

statement-table/src/lib.rs

@@ -16,7 +16,7 @@
 
 pub mod generic;
 
-pub use generic::{Context, Table};
+pub use generic::{Config, Context, Table};
 
 /// Concrete instantiations suitable for v2 primitives.
 pub mod v2 {