Break the ref cycle (#11371)

substrate/bin/node/cli/tests/running_the_node_and_interrupt.rs

@@ -38,6 +38,7 @@ async fn running_the_node_works_and_can_be_interrupted() {
 			Command::new(cargo_bin("substrate"))
 				.args(&["--dev", "-d"])
 				.arg(base_path.path())
+				.arg("--db=paritydb")
 				.arg("--no-hardware-benchmarks")
 				.spawn()
 				.unwrap(),
@@ -52,6 +53,12 @@ async fn running_the_node_works_and_can_be_interrupted() {
 			"the process must exit gracefully after signal {}",
 			signal,
 		);
+		// Check if the database was closed gracefully. If it was not,
+		// there may exist a ref cycle that prevents the Client from being dropped properly.
+		//
+		// parity-db only writes the stats file on clean shutdown.
+		let stats_file = base_path.path().join("chains/dev/paritydb/full/stats.txt");
+		assert!(std::path::Path::exists(&stats_file));
 	}
 
 	run_command_and_kill(SIGINT).await;

substrate/client/consensus/babe/src/lib.rs

@@ -1783,9 +1783,13 @@ where
 	// startup rather than waiting until importing the next epoch change block.
 	prune_finalized(client.clone(), &mut epoch_changes.shared_data())?;
 
-	let client_clone = client.clone();
+	let client_weak = Arc::downgrade(&client);
 	let on_finality = move |summary: &FinalityNotification<Block>| {
-		aux_storage_cleanup(client_clone.as_ref(), summary)
+		if let Some(client) = client_weak.upgrade() {
+			aux_storage_cleanup(client.as_ref(), summary)
+		} else {
+			Default::default()
+		}
 	};
 	client.register_finality_action(Box::new(on_finality));