Check if the store already has a statement before processing

Author: AndreiEres

substrate/client/network/statement/src/lib.rs

@@ -88,6 +88,7 @@ const LOG_TARGET: &str = "statement-gossip";
 
 struct Metrics {
 	propagated_statements: Counter<U64>,
+	known_statements_received: Counter<U64>,
 }
 
 impl Metrics {
@@ -100,6 +101,13 @@ impl Metrics {
 				)?,
 				r,
 			)?,
+			known_statements_received: register(
+				Counter::new(
+					"substrate_sync_known_statement_received",
+					"Number of statements received via gossiping that were already in the statement store",
+				)?,
+				r,
+			)?,
 		})
 	}
 }
@@ -388,6 +396,13 @@ where
 
 				self.network.report_peer(who, rep::ANY_STATEMENT);
 
+				if self.statement_store.has_statement(&hash) {
+					if let Some(ref metrics) = self.metrics {
+						metrics.known_statements_received.inc();
+					}
+					continue;
+				}
+
 				match self.pending_statements_peers.entry(hash) {
 					Entry::Vacant(entry) => {
 						let (completion_sender, completion_receiver) = oneshot::channel();

substrate/client/statement-store/src/lib.rs

@@ -833,6 +833,10 @@ impl StatementStore for Store {
 		)
 	}
 
+	fn has_statement(&self, hash: &Hash) -> bool {
+		self.index.read().entries.contains_key(hash)
+	}
+
 	/// Return the data of all known statements which include all topics and have no `DecryptionKey`
 	/// field.
 	fn broadcasts(&self, match_all_topics: &[Topic]) -> Result<Vec<Vec<u8>>> {

substrate/primitives/statement-store/src/store_api.rs

@@ -75,6 +75,11 @@ pub trait StatementStore: Send + Sync {
 	/// Get statement by hash.
 	fn statement(&self, hash: &Hash) -> Result<Option<Statement>>;
 
+	/// Check if statement exists in the store
+	///
+	/// Fast index check without accessing the DB.
+	fn has_statement(&self, hash: &Hash) -> bool;
+
 	/// Return the data of all known statements which include all topics and have no `DecryptionKey`
 	/// field.
 	fn broadcasts(&self, match_all_topics: &[Topic]) -> Result<Vec<Vec<u8>>>;