client/network: Remove option to disable yamux flow control (#7358)

With the `OnRead` flow control option yamux "send[s] window updates only
when data is read on the receiving end" and not as soon as "a Stream's
receive window drops to 0".

Yamux flow control has proven itself. This commit removes the feature
flag. Yamux flow control is now always enabled.

client/cli/src/params/network_params.rs

@@ -92,11 +92,6 @@ pub struct NetworkParams {
 	#[structopt(flatten)]
 	pub node_key_params: NodeKeyParams,
 
-	/// Disable the yamux flow control. This option will be removed in the future once there is
-	/// enough confidence that this feature is properly working.
-	#[structopt(long)]
-	pub no_yamux_flow_control: bool,
-
 	/// Enable peer discovery on local networks.
 	///
 	/// By default this option is true for `--dev` and false otherwise.
@@ -158,7 +153,6 @@ impl NetworkParams {
 				enable_mdns: !is_dev && !self.no_mdns,
 				allow_private_ipv4: !self.no_private_ipv4,
 				wasm_external_transport: None,
-				use_yamux_flow_control: !self.no_yamux_flow_control,
 			},
 			max_parallel_downloads: self.max_parallel_downloads,
 			allow_non_globals_in_dht: self.discover_local || is_dev,

client/network/src/config.rs

@@ -451,7 +451,6 @@ impl NetworkConfiguration {
 				enable_mdns: false,
 				allow_private_ipv4: true,
 				wasm_external_transport: None,
-				use_yamux_flow_control: false,
 			},
 			max_parallel_downloads: 5,
 			allow_non_globals_in_dht: false,
@@ -519,8 +518,6 @@ pub enum TransportConfig {
 		/// This parameter exists whatever the target platform is, but it is expected to be set to
 		/// `Some` only when compiling for WASM.
 		wasm_external_transport: Option<wasm_ext::ExtTransport>,
-		/// Use flow control for yamux streams if set to true.
-		use_yamux_flow_control: bool,
 	},
 
 	/// Only allow connections within the same process.

client/network/src/service.rs

@@ -336,12 +336,12 @@ impl<B: BlockT + 'static, H: ExHashT> NetworkWorker<B, H> {
 				behaviour.register_notifications_protocol(*engine_id, protocol_name.clone());
 			}
 			let (transport, bandwidth) = {
-				let (config_mem, config_wasm, flowctrl) = match params.network_config.transport {
-					TransportConfig::MemoryOnly => (true, None, false),
-					TransportConfig::Normal { wasm_external_transport, use_yamux_flow_control, .. } =>
-						(false, wasm_external_transport, use_yamux_flow_control)
+				let (config_mem, config_wasm) = match params.network_config.transport {
+					TransportConfig::MemoryOnly => (true, None),
+					TransportConfig::Normal { wasm_external_transport, .. } =>
+						(false, wasm_external_transport)
 				};
-				transport::build_transport(local_identity, config_mem, config_wasm, flowctrl)
+				transport::build_transport(local_identity, config_mem, config_wasm)
 			};
 			let mut builder = SwarmBuilder::new(transport, behaviour, local_peer_id.clone())
 				.peer_connection_limit(crate::MAX_CONNECTIONS_PER_PEER)

client/network/src/transport.rs

@@ -41,7 +41,6 @@ pub fn build_transport(
 	keypair: identity::Keypair,
 	memory_only: bool,
 	wasm_external_transport: Option<wasm_ext::ExtTransport>,
-	use_yamux_flow_control: bool
 ) -> (Boxed<(PeerId, StreamMuxerBox), io::Error>, Arc<BandwidthSinks>) {
 	// Build the base layer of the transport.
 	let transport = if let Some(t) = wasm_external_transport {
@@ -110,12 +109,9 @@ pub fn build_transport(
 		mplex_config.max_buffer_len(usize::MAX);
 
 		let mut yamux_config = libp2p::yamux::Config::default();
-
-		if use_yamux_flow_control {
-			// Enable proper flow-control: window updates are only sent when
-			// buffered data has been consumed.
-			yamux_config.set_window_update_mode(libp2p::yamux::WindowUpdateMode::OnRead);
-		}
+		// Enable proper flow-control: window updates are only sent when
+		// buffered data has been consumed.
+		yamux_config.set_window_update_mode(libp2p::yamux::WindowUpdateMode::OnRead);
 
 		core::upgrade::SelectUpgrade::new(yamux_config, mplex_config)
 			.map_inbound(move |muxer| core::muxing::StreamMuxerBox::new(muxer))

client/service/test/src/lib.rs

@@ -225,7 +225,6 @@ fn node_config<G: RuntimeGenesis + 'static, E: ChainSpecExtension + Clone + 'sta
 		enable_mdns: false,
 		allow_private_ipv4: true,
 		wasm_external_transport: None,
-		use_yamux_flow_control: true,
 	};
 
 	Configuration {

utils/browser/src/lib.rs

@@ -57,7 +57,6 @@ where
 		wasm_external_transport: Some(transport.clone()),
 		allow_private_ipv4: true,
 		enable_mdns: false,
-		use_yamux_flow_control: true,
 	};
 
 	let config = Configuration {