core: allow setting max ws rpc connections (#2632)

* core: allow setting max ws rpc connections

* style: break long lines

* core: fix service tests

substrate/core/cli/src/lib.rs

@@ -487,6 +487,7 @@ where
 	config.rpc_ws = Some(
 		parse_address(&format!("{}:{}", ws_interface, 9944), cli.ws_port)?
 	);
+	config.rpc_ws_max_connections = cli.ws_max_connections;
 	config.rpc_cors = cli.rpc_cors.unwrap_or_else(|| if is_dev {
 		log::warn!("Running in --dev mode, RPC CORS has been disabled.");
 		None

substrate/core/cli/src/params.rs

@@ -333,6 +333,10 @@ pub struct RunCmd {
 	#[structopt(long = "ws-port", value_name = "PORT")]
 	pub ws_port: Option<u16>,
 
+	/// Maximum number of WS RPC server connections.
+	#[structopt(long = "ws-max-connections", value_name = "COUNT")]
+	pub ws_max_connections: Option<usize>,
+
 	/// Specify browser Origins allowed to access the HTTP & WS RPC servers.
 	/// It's a comma-separated list of origins (protocol://domain or special `null` value).
 	/// Value of `all` will disable origin validation.