Dont block tokio reactor waiting on user input

When we moved the CLI input reading into a `tokio::select`, we
ended up blocking the tokio reactor by reading from stdin in a
standard tokio future. Instead, we need to let tokio know that
we're running a largely-blocking task.

Author: TheBlueMatt

src/cli.rs

@@ -60,7 +60,7 @@ impl Writeable for UserOnionMessageContents {
 	}
 }
 
-pub(crate) async fn poll_for_user_input(
+pub(crate) fn poll_for_user_input(
 	peer_manager: Arc<PeerManager>, channel_manager: Arc<ChannelManager>,
 	keys_manager: Arc<KeysManager>, network_graph: Arc<NetworkGraph>,
 	onion_messenger: Arc<OnionMessenger>, inbound_payments: Arc<Mutex<PaymentInfoStorage>>,
@@ -112,8 +112,12 @@ pub(crate) async fn poll_for_user_input(
 						continue;
 					}
 
-					if connect_peer_if_necessary(pubkey, peer_addr, peer_manager.clone())
-						.await
+					if tokio::runtime::Handle::current()
+						.block_on(connect_peer_if_necessary(
+							pubkey,
+							peer_addr,
+							peer_manager.clone(),
+						))
 						.is_err()
 					{
 						continue;
@@ -259,8 +263,12 @@ pub(crate) async fn poll_for_user_input(
 								continue;
 							}
 						};
-					if connect_peer_if_necessary(pubkey, peer_addr, peer_manager.clone())
-						.await
+					if tokio::runtime::Handle::current()
+						.block_on(connect_peer_if_necessary(
+							pubkey,
+							peer_addr,
+							peer_manager.clone(),
+						))
 						.is_ok()
 					{
 						println!("SUCCESS: connected to peer {}", pubkey);

src/main.rs

@@ -943,19 +943,25 @@ async fn start_ldk() {
 	));
 
 	// Start the CLI.
-	let cli_poll = tokio::spawn(cli::poll_for_user_input(
-		Arc::clone(&peer_manager),
-		Arc::clone(&channel_manager),
-		Arc::clone(&keys_manager),
-		Arc::clone(&network_graph),
-		Arc::clone(&onion_messenger),
-		inbound_payments,
-		outbound_payments,
-		ldk_data_dir,
-		network,
-		Arc::clone(&logger),
-		Arc::clone(&persister),
-	));
+	let cli_channel_manager = Arc::clone(&channel_manager);
+	let cli_persister = Arc::clone(&persister);
+	let cli_logger = Arc::clone(&logger);
+	let cli_peer_manager = Arc::clone(&peer_manager);
+	let cli_poll = tokio::task::spawn_blocking(move || {
+		cli::poll_for_user_input(
+			cli_peer_manager,
+			cli_channel_manager,
+			keys_manager,
+			network_graph,
+			onion_messenger,
+			inbound_payments,
+			outbound_payments,
+			ldk_data_dir,
+			network,
+			cli_logger,
+			cli_persister,
+		)
+	});
 
 	// Exit if either CLI polling exits or the background processor exits (which shouldn't happen
 	// unless we fail to write to the filesystem).