Network shutdown

ethcore/src/service.rs

@@ -41,6 +41,10 @@ pub enum SyncMessage {
 	NewChainHead,
 	/// A block is ready
 	BlockVerified,
+	/// Start network command.
+	StartNetwork,
+	/// Stop network command.
+	StopNetwork,
 }
 
 /// IO Message type used for Network service
@@ -48,17 +52,20 @@ pub type NetSyncMessage = NetworkIoMessage<SyncMessage>;
 
 /// Client service setup. Creates and registers client and network services with the IO subsystem.
 pub struct ClientService {
-	net_service: NetworkService<SyncMessage>,
+	net_service: Arc<NetworkService<SyncMessage>>,
 	client: Arc<Client>,
 	panic_handler: Arc<PanicHandler>
 }
 
 impl ClientService {
 	/// Start the service in a separate thread.
-	pub fn start(config: ClientConfig, spec: Spec, net_config: NetworkConfiguration, db_path: &Path, miner: Arc<Miner>) -> Result<ClientService, Error> {
+	pub fn start(config: ClientConfig, spec: Spec, net_config: NetworkConfiguration, db_path: &Path, miner: Arc<Miner>, enable_network: bool) -> Result<ClientService, Error> {
 		let panic_handler = PanicHandler::new_in_arc();
-		let mut net_service = try!(NetworkService::start(net_config));
+		let net_service = try!(NetworkService::new(net_config));
 		panic_handler.forward_from(&net_service);
+		if enable_network {
+			try!(net_service.start());
+		}
 
 		info!("Starting {}", net_service.host_info());
 		info!("Configured for {} using {:?} engine", spec.name, spec.engine.name());
@@ -70,7 +77,7 @@ impl ClientService {
 		try!(net_service.io().register_handler(client_io));
 
 		Ok(ClientService {
-			net_service: net_service,
+			net_service: Arc::new(net_service),
 			client: client,
 			panic_handler: panic_handler,
 		})
@@ -82,8 +89,8 @@ impl ClientService {
 	}
 
 	/// Get general IO interface
-	pub fn io(&mut self) -> &mut IoService<NetSyncMessage> {
+	pub fn register_io_handler(&self, handler: Arc<IoHandler<NetSyncMessage> + Send>) -> Result<(), IoError> {
-		self.net_service.io()
+		self.net_service.io().register_handler(handler)
 	}
 
 	/// Get client interface
@@ -92,8 +99,8 @@ impl ClientService {
 	}
 
 	/// Get network service component
-	pub fn network(&mut self) -> &mut NetworkService<SyncMessage> {
+	pub fn network(&mut self) -> Arc<NetworkService<SyncMessage>> {
-		&mut self.net_service
+		self.net_service.clone()
 	}
 }
 

parity/cli.rs

@@ -52,6 +52,7 @@ Account Options:
   --no-import-keys         Do not import keys from legacy clients.
 
 Networking Options:
+  --no-network             Disable p2p networking.
   --port PORT              Override the port on which the node should listen
                            [default: 30303].
   --peers NUM              Try to maintain that many peers [default: 25].
@@ -266,6 +267,7 @@ pub struct Args {
 	pub flag_format: Option<String>,
 	pub flag_jitvm: bool,
 	pub flag_no_color: bool,
+	pub flag_no_network: bool,
 	// legacy...
 	pub flag_geth: bool,
 	pub flag_nodekey: Option<String>,

parity/io_handler.rs

@@ -16,10 +16,10 @@
 
 use std::sync::Arc;
 use ethcore::client::Client;
-use ethcore::service::NetSyncMessage;
+use ethcore::service::{NetSyncMessage, SyncMessage};
 use ethsync::EthSync;
 use util::keys::store::AccountService;
-use util::{TimerToken, IoHandler, IoContext};
+use util::{TimerToken, IoHandler, IoContext, NetworkService, NetworkIoMessage};
 
 use informant::Informant;
 
@@ -33,6 +33,7 @@ pub struct ClientIoHandler {
 	pub sync: Arc<EthSync>,
 	pub accounts: Arc<AccountService>,
 	pub info: Informant,
+	pub network: Arc<NetworkService<SyncMessage>>,
 }
 
 impl IoHandler<NetSyncMessage> for ClientIoHandler {
@@ -48,6 +49,20 @@ impl IoHandler<NetSyncMessage> for ClientIoHandler {
 			_ => {}
 		}
 	}
+
+	fn message(&self, _io: &IoContext<NetSyncMessage>, message: &NetSyncMessage) {
+		match *message {
+			NetworkIoMessage::User(SyncMessage::StartNetwork) => {
+				info!("Starting network");
+				self.network.start().unwrap_or_else(|e| warn!("Error starting network: {:?}", e));
+			},
+			NetworkIoMessage::User(SyncMessage::StopNetwork) => {
+				info!("Stopping network");
+				self.network.stop().unwrap_or_else(|e| warn!("Error stopping network: {:?}", e));
+			},
+			_ => {/* Ignore other messages */},
+		}
+	}
 }
 
 

parity/main.rs

@@ -198,7 +198,7 @@ fn execute_client(conf: Configuration, spec: Spec, client_config: ClientConfig)
 
 	// Build client
 	let mut service = ClientService::start(
-		client_config, spec, net_settings, Path::new(&conf.path()), miner.clone()
+		client_config, spec, net_settings, Path::new(&conf.path()), miner.clone(), !conf.args.flag_no_network
 	).unwrap_or_else(|e| die_with_error("Client", e));
 
 	panic_handler.forward_from(&service);
@@ -208,7 +208,7 @@ fn execute_client(conf: Configuration, spec: Spec, client_config: ClientConfig)
 	let network_settings = Arc::new(conf.network_settings());
 
 	// Sync
-	let sync = EthSync::register(service.network(), sync_config, client.clone());
+	let sync = EthSync::register(service.network().deref(), sync_config, client.clone());
 
 	let deps_for_rpc_apis = Arc::new(rpc_apis::Dependencies {
 		signer_port: conf.signer_port(),
@@ -269,8 +269,9 @@ fn execute_client(conf: Configuration, spec: Spec, client_config: ClientConfig)
 		info: Informant::new(conf.have_color()),
 		sync: sync.clone(),
 		accounts: account_service.clone(),
+		network: service.network(),
 	});
-	service.io().register_handler(io_handler).expect("Error registering IO handler");
+	service.register_io_handler(io_handler).expect("Error registering IO handler");
 
 	// Handle exit
 	wait_for_exit(panic_handler, rpc_server, dapps_server, signer_server);
@@ -309,7 +310,7 @@ fn execute_export(conf: Configuration) {
 
 	// Build client
 	let service = ClientService::start(
-		client_config, spec, net_settings, Path::new(&conf.path()), Arc::new(Miner::default()),
+		client_config, spec, net_settings, Path::new(&conf.path()), Arc::new(Miner::default()), false
 	).unwrap_or_else(|e| die_with_error("Client", e));
 
 	panic_handler.forward_from(&service);
@@ -380,7 +381,7 @@ fn execute_import(conf: Configuration) {
 
 	// Build client
 	let service = ClientService::start(
-		client_config, spec, net_settings, Path::new(&conf.path()), Arc::new(Miner::default()),
+		client_config, spec, net_settings, Path::new(&conf.path()), Arc::new(Miner::default()), false
 	).unwrap_or_else(|e| die_with_error("Client", e));
 
 	panic_handler.forward_from(&service);

rpc/src/v1/impls/net.rs

@@ -47,4 +47,14 @@ impl<S> Net for NetClient<S> where S: SyncProvider + 'static {
 		// right now (11 march 2016), we are always listening for incoming connections
 		Ok(Value::Bool(true))
 	}
+
+	fn start_network(&self, _: Params) -> Result<Value, Error> {
+		take_weak!(self.sync).start_network();
+		Ok(Value::Bool(true))
+	}
+
+	fn stop_network(&self, _: Params) -> Result<Value, Error> {
+		take_weak!(self.sync).stop_network();
+		Ok(Value::Bool(true))
+	}
 }

rpc/src/v1/tests/helpers/sync_provider.rs

@@ -59,5 +59,11 @@ impl SyncProvider for TestSyncProvider {
 	fn status(&self) -> SyncStatus {
 		self.status.read().unwrap().clone()
 	}
+
+	fn start_network(&self) {
+	}
+
+	fn stop_network(&self) {
+	}
 }
 

rpc/src/v1/traits/net.rs

@@ -30,12 +30,20 @@ pub trait Net: Sized + Send + Sync + 'static {
 	/// Otherwise false.
 	fn is_listening(&self, _: Params) -> Result<Value, Error>;
 
+	/// Start the network.
+	fn start_network(&self, _: Params) -> Result<Value, Error>;
+
+	/// Stop the network.
+	fn stop_network(&self, _: Params) -> Result<Value, Error>;
+
 	/// Should be used to convert object to io delegate.
 	fn to_delegate(self) -> IoDelegate<Self> {
 		let mut delegate = IoDelegate::new(Arc::new(self));
 		delegate.add_method("net_version", Net::version);
 		delegate.add_method("net_peerCount", Net::peer_count);
 		delegate.add_method("net_listening", Net::is_listening);
+		delegate.add_method("net_start", Net::start_network);
+		delegate.add_method("net_stop", Net::stop_network);
 		delegate
 	}
 }

sync/src/lib.rs

@@ -66,8 +66,10 @@ use util::network::{NetworkProtocolHandler, NetworkService, NetworkContext, Peer
 use util::TimerToken;
 use util::{U256, ONE_U256};
 use ethcore::client::Client;
-use ethcore::service::SyncMessage;
+use ethcore::service::{SyncMessage, NetSyncMessage};
 use io::NetSyncIo;
+use util::io::IoChannel;
+use util::NetworkIoMessage;
 use chain::ChainSync;
 
 mod chain;
@@ -98,6 +100,10 @@ impl Default for SyncConfig {
 pub trait SyncProvider: Send + Sync {
 	/// Get sync status
 	fn status(&self) -> SyncStatus;
+	/// Start the network
+	fn start_network(&self);
+	/// Stop the network
+	fn stop_network(&self);
 }
 
 /// Ethereum network protocol handler
@@ -105,18 +111,21 @@ pub struct EthSync {
 	/// Shared blockchain client. TODO: this should evetually become an IPC endpoint
 	chain: Arc<Client>,
 	/// Sync strategy
-	sync: RwLock<ChainSync>
+	sync: RwLock<ChainSync>,
+	/// IO communication chnnel.
+	io_channel: RwLock<IoChannel<NetSyncMessage>>,
 }
 
 pub use self::chain::{SyncStatus, SyncState};
 
 impl EthSync {
 	/// Creates and register protocol with the network service
-	pub fn register(service: &mut NetworkService<SyncMessage>, config: SyncConfig, chain: Arc<Client>) -> Arc<EthSync> {
+	pub fn register(service: &NetworkService<SyncMessage>, config: SyncConfig, chain: Arc<Client>) -> Arc<EthSync> {
 		let sync = ChainSync::new(config, chain.deref());
 		let sync = Arc::new(EthSync {
 			chain: chain,
 			sync: RwLock::new(sync),
+			io_channel: RwLock::new(IoChannel::disconnected()),
 		});
 		service.register_protocol(sync.clone(), "eth", &[62u8, 63u8]).expect("Error registering eth protocol handler");
 		sync
@@ -138,11 +147,20 @@ impl SyncProvider for EthSync {
 	fn status(&self) -> SyncStatus {
 		self.sync.read().unwrap().status()
 	}
+
+	fn start_network(&self) {
+		self.io_channel.read().unwrap().send(NetworkIoMessage::User(SyncMessage::StartNetwork)).expect("Error sending IO notification");
+	}
+
+	fn stop_network(&self) {
+		self.io_channel.read().unwrap().send(NetworkIoMessage::User(SyncMessage::StopNetwork)).expect("Error sending IO notification");
+	}
 }
 
 impl NetworkProtocolHandler<SyncMessage> for EthSync {
 	fn initialize(&self, io: &NetworkContext<SyncMessage>) {
 		io.register_timer(0, 1000).expect("Error registering sync timer");
+		*self.io_channel.write().unwrap() = io.io_channel();
 	}
 
 	fn read(&self, io: &NetworkContext<SyncMessage>, peer: &PeerId, packet_id: u8, data: &[u8]) {

util/src/io/service.rs

@@ -17,10 +17,12 @@
 use std::sync::*;
 use std::thread::{self, JoinHandle};
 use std::collections::HashMap;
+use std::ops::Deref;
 use mio::*;
+use crossbeam::sync::chase_lev;
+use slab::Slab;
 use error::*;
 use io::{IoError, IoHandler};
-use crossbeam::sync::chase_lev;
 use io::worker::{Worker, Work, WorkType};
 use panics::*;
 
@@ -33,6 +35,14 @@ pub type HandlerId = usize;
 
 /// Maximum number of tokens a handler can use
 pub const TOKENS_PER_HANDLER: usize = 16384;
+const MAX_HANDLERS: usize = 8;
+
+fn compare_arcs<T: ?Sized>(a: Arc<T>, b: Arc<T>) -> bool {
+	let p1 = &*a as *const T;
+	let p2 = &*b as *const T;
+	info!("{:p} == {:p} : {}", p1, p2 , p1 == p2);
+	p1 == p2
+}
 
 /// Messages used to communicate with the event loop from other threads.
 #[derive(Clone)]
@@ -43,6 +53,9 @@ pub enum IoMessage<Message> where Message: Send + Clone + Sized {
 	AddHandler {
 		handler: Arc<IoHandler<Message>+Send>,
 	},
+	RemoveHandler {
+		handler_id: HandlerId,
+	},
 	AddTimer {
 		handler_id: HandlerId,
 		token: TimerToken,
@@ -138,6 +151,15 @@ impl<Message> IoContext<Message> where Message: Send + Clone + 'static {
 	pub fn channel(&self) -> IoChannel<Message> {
 		self.channel.clone()
 	}
+
+	/// Unregister current IO handler.
+	pub fn unregister_handler(&self) -> Result<(), IoError> {
+		try!(self.channel.send_io(IoMessage::RemoveHandler {
+			handler_id: self.handler,
+		}));
+		Ok(())
+	}
+
 }
 
 #[derive(Clone)]
@@ -149,7 +171,7 @@ struct UserTimer {
 /// Root IO handler. Manages user handlers, messages and IO timers.
 pub struct IoManager<Message> where Message: Send + Sync {
 	timers: Arc<RwLock<HashMap<HandlerId, UserTimer>>>,
-	handlers: Vec<Arc<IoHandler<Message>>>,
+	handlers: Slab<Arc<IoHandler<Message>>, HandlerId>,
 	workers: Vec<Worker>,
 	worker_channel: chase_lev::Worker<Work<Message>>,
 	work_ready: Arc<Condvar>,
@@ -175,7 +197,7 @@ impl<Message> IoManager<Message> where Message: Send + Sync + Clone + 'static {
 
 		let mut io = IoManager {
 			timers: Arc::new(RwLock::new(HashMap::new())),
-			handlers: Vec::new(),
+			handlers: Slab::new(MAX_HANDLERS),
 			worker_channel: worker,
 			workers: workers,
 			work_ready: work_ready,
@@ -192,10 +214,7 @@ impl<Message> Handler for IoManager<Message> where Message: Send + Clone + Sync
 	fn ready(&mut self, _event_loop: &mut EventLoop<Self>, token: Token, events: EventSet) {
 		let handler_index  = token.as_usize() / TOKENS_PER_HANDLER;
 		let token_id  = token.as_usize() % TOKENS_PER_HANDLER;
-		if handler_index >= self.handlers.len() {
+		let handler = self.handlers.get(handler_index).unwrap_or_else(|| panic!("Unexpected stream token: {}", token.as_usize())).clone();
-			panic!("Unexpected stream token: {}", token.as_usize());
-		}
-		let handler = self.handlers[handler_index].clone();
 
 		if events.is_hup() {
 			self.worker_channel.push(Work { work_type: WorkType::Hup, token: token_id, handler: handler.clone(), handler_id: handler_index });
@@ -214,12 +233,9 @@ impl<Message> Handler for IoManager<Message> where Message: Send + Clone + Sync
 	fn timeout(&mut self, event_loop: &mut EventLoop<Self>, token: Token) {
 		let handler_index  = token.as_usize()  / TOKENS_PER_HANDLER;
 		let token_id  = token.as_usize()  % TOKENS_PER_HANDLER;
-		if handler_index >= self.handlers.len() {
+		let handler = self.handlers.get(handler_index).unwrap_or_else(|| panic!("Unexpected stream token: {}", token.as_usize())).clone();
-			panic!("Unexpected timer token: {}", token.as_usize());
-		}
 		if let Some(timer) = self.timers.read().unwrap().get(&token.as_usize()) {
 			event_loop.timeout_ms(token, timer.delay).expect("Error re-registering user timer");
-			let handler = self.handlers[handler_index].clone();
 			self.worker_channel.push(Work { work_type: WorkType::Timeout, token: token_id, handler: handler, handler_id: handler_index });
 			self.work_ready.notify_all();
 		}
@@ -232,12 +248,14 @@ impl<Message> Handler for IoManager<Message> where Message: Send + Clone + Sync
 				event_loop.shutdown();
 			},
 			IoMessage::AddHandler { handler } => {
-				let handler_id = {
+				let handler_id = self.handlers.insert(handler.clone()).unwrap_or_else(|_| panic!("Too many handlers registered"));
-					self.handlers.push(handler.clone());
-					self.handlers.len() - 1
-				};
 				handler.initialize(&IoContext::new(IoChannel::new(event_loop.channel()), handler_id));
 			},
+			IoMessage::RemoveHandler { handler_id } => {
+				// TODO: flush event loop
+				self.handlers.remove(handler_id);
+				info!("{} left", self.handlers.count());
+			},
 			IoMessage::AddTimer { handler_id, token, delay } => {
 				let timer_id = token + handler_id * TOKENS_PER_HANDLER;
 				let timeout = event_loop.timeout_ms(Token(timer_id), delay).expect("Error registering user timer");
@@ -267,9 +285,12 @@ impl<Message> Handler for IoManager<Message> where Message: Send + Clone + Sync
 				handler.update_stream(token, Token(token + handler_id * TOKENS_PER_HANDLER), event_loop);
 			},
 			IoMessage::UserMessage(data) => {
-				for n in 0 .. self.handlers.len() {
+				//TODO: better way to iterate the slab
-					let handler = self.handlers[n].clone();
+				for id in 0 .. MAX_HANDLERS {
-					self.worker_channel.push(Work { work_type: WorkType::Message(data.clone()), token: 0, handler: handler, handler_id: n });
+					if let Some(h) = self.handlers.get(id) {
+						let handler = h.clone();
+						self.worker_channel.push(Work { work_type: WorkType::Message(data.clone()), token: 0, handler: handler, handler_id: id });
+					}
 				}
 				self.work_ready.notify_all();
 			}
@@ -351,8 +372,8 @@ impl<Message> IoService<Message> where Message: Send + Sync + Clone + 'static {
 		})
 	}
 
-	/// Regiter a IO hadnler with the event loop.
+	/// Regiter an IO handler with the event loop.
-	pub fn register_handler(&mut self, handler: Arc<IoHandler<Message>+Send>) -> Result<(), IoError> {
+	pub fn register_handler(&self, handler: Arc<IoHandler<Message>+Send>) -> Result<(), IoError> {
 		try!(self.host_channel.send(IoMessage::AddHandler {
 			handler: handler,
 		}));
@@ -360,13 +381,13 @@ impl<Message> IoService<Message> where Message: Send + Sync + Clone + 'static {
 	}
 
 	/// Send a message over the network. Normaly `HostIo::send` should be used. This can be used from non-io threads.
-	pub fn send_message(&mut self, message: Message) -> Result<(), IoError> {
+	pub fn send_message(&self, message: Message) -> Result<(), IoError> {
 		try!(self.host_channel.send(IoMessage::UserMessage(message)));
 		Ok(())
 	}
 
 	/// Create a new message channel
-	pub fn channel(&mut self) -> IoChannel<Message> {
+	pub fn channel(&self) -> IoChannel<Message> {
 		IoChannel { channel: Some(self.host_channel.clone()) }
 	}
 }

util/src/network/host.rs

@@ -49,7 +49,7 @@ const MAX_HANDSHAKES: usize = 80;
 const MAX_HANDSHAKES_PER_ROUND: usize = 32;
 const MAINTENANCE_TIMEOUT: u64 = 1000;
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 /// Network service configuration
 pub struct NetworkConfiguration {
 	/// Directory path to store network configuration. None means nothing will be saved
@@ -233,6 +233,11 @@ impl<'s, Message> NetworkContext<'s, Message> where Message: Send + Sync + Clone
 		self.io.message(NetworkIoMessage::User(msg));
 	}
 
+	/// Send an IO message
+	pub fn io_channel(&self) -> IoChannel<NetworkIoMessage<Message>> {
+		self.io.channel()
+	}
+
 	/// Disable current protocol capability for given peer. If no capabilities left peer gets disconnected.
 	pub fn disable_peer(&self, peer: PeerId) {
 		//TODO: remove capability, disconnect if no capabilities left
@@ -327,7 +332,7 @@ pub struct Host<Message> where Message: Send + Sync + Clone {
 
 impl<Message> Host<Message> where Message: Send + Sync + Clone {
 	/// Create a new instance
-	pub fn new(config: NetworkConfiguration) -> Result<Host<Message>, UtilError> {
+	pub fn new(config: NetworkConfiguration, stats: Arc<NetworkStats>) -> Result<Host<Message>, UtilError> {
 		let mut listen_address = match config.listen_address {
 			None => SocketAddr::from_str("0.0.0.0:30304").unwrap(),
 			Some(addr) => addr,
@@ -371,7 +376,7 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 			handlers: RwLock::new(HashMap::new()),
 			timers: RwLock::new(HashMap::new()),
 			timer_counter: RwLock::new(USER_TIMER),
-			stats: Arc::new(NetworkStats::default()),
+			stats: stats,
 			pinned_nodes: Vec::new(),
 			num_sessions: AtomicUsize::new(0),
 		};
@@ -383,10 +388,6 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 		Ok(host)
 	}
 
-	pub fn stats(&self) -> Arc<NetworkStats> {
-		self.stats.clone()
-	}
-
 	pub fn add_node(&mut self, id: &str) {
 		match Node::from_str(id) {
 			Err(e) => { debug!(target: "network", "Could not add node {}: {:?}", id, e); },
@@ -401,8 +402,8 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 		}
 	}
 
-	pub fn client_version(&self) -> String {
+	pub fn client_version() -> String {
-		self.info.read().unwrap().client_version.clone()
+		version()
 	}
 
 	pub fn external_url(&self) -> Option<String> {
@@ -415,6 +416,23 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 		r
 	}
 
+	pub fn stop(&self, io: &IoContext<NetworkIoMessage<Message>>) -> Result<(), UtilError> {
+		let mut to_kill = Vec::new();
+		for e in self.sessions.write().unwrap().iter_mut() {
+			let mut s = e.lock().unwrap();
+			if !s.keep_alive(io) {
+				s.disconnect(io, DisconnectReason::PingTimeout);
+				to_kill.push(s.token());
+			}
+		}
+		for p in to_kill {
+			trace!(target: "network", "Ping timeout: {}", p);
+			self.kill_connection(p, io, true);
+		}
+		io.unregister_handler();
+		Ok(())
+	}
+
 	fn init_public_interface(&self, io: &IoContext<NetworkIoMessage<Message>>) -> Result<(), UtilError> {
 		io.clear_timer(INIT_PUBLIC).unwrap();
 		if self.info.read().unwrap().public_endpoint.is_some() {
@@ -767,6 +785,13 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 	}
 }
 
+
+impl<Message> Drop for Host<Message> where Message: Send + Sync + Clone {
+	fn drop(&mut self) {
+		info!("Dropping host");
+	}
+}
+
 impl<Message> IoHandler<NetworkIoMessage<Message>> for Host<Message> where Message: Send + Sync + Clone + 'static {
 	/// Initialize networking
 	fn initialize(&self, io: &IoContext<NetworkIoMessage<Message>>) {

util/src/network/service.rs

@@ -28,33 +28,33 @@ use io::*;
 pub struct NetworkService<Message> where Message: Send + Sync + Clone + 'static {
 	io_service: IoService<NetworkIoMessage<Message>>,
 	host_info: String,
-	host: Arc<Host<Message>>,
+	host: RwLock<Option<Arc<Host<Message>>>>,
 	stats: Arc<NetworkStats>,
-	panic_handler: Arc<PanicHandler>
+	panic_handler: Arc<PanicHandler>,
+	config: NetworkConfiguration,
 }
 
 impl<Message> NetworkService<Message> where Message: Send + Sync + Clone + 'static {
 	/// Starts IO event loop
-	pub fn start(config: NetworkConfiguration) -> Result<NetworkService<Message>, UtilError> {
+	pub fn new(config: NetworkConfiguration) -> Result<NetworkService<Message>, UtilError> {
 		let panic_handler = PanicHandler::new_in_arc();
-		let mut io_service = try!(IoService::<NetworkIoMessage<Message>>::start());
+		let io_service = try!(IoService::<NetworkIoMessage<Message>>::start());
 		panic_handler.forward_from(&io_service);
 
-		let host = Arc::new(try!(Host::new(config)));
+		let stats = Arc::new(NetworkStats::new());
-		let stats = host.stats().clone();
+		let host_info = Host::<Message>::client_version();
-		let host_info = host.client_version();
-		try!(io_service.register_handler(host.clone()));
 		Ok(NetworkService {
 			io_service: io_service,
 			host_info: host_info,
 			stats: stats,
 			panic_handler: panic_handler,
-			host: host,
+			host: RwLock::new(None),
+			config: config,
 		})
 	}
 
 	/// Regiter a new protocol handler with the event loop.
-	pub fn register_protocol(&mut self, handler: Arc<NetworkProtocolHandler<Message>+Send + Sync>, protocol: ProtocolId, versions: &[u8]) -> Result<(), NetworkError> {
+	pub fn register_protocol(&self, handler: Arc<NetworkProtocolHandler<Message>+Send + Sync>, protocol: ProtocolId, versions: &[u8]) -> Result<(), NetworkError> {
 		try!(self.io_service.send_message(NetworkIoMessage::AddHandler {
 			handler: handler,
 			protocol: protocol,
@@ -69,8 +69,8 @@ impl<Message> NetworkService<Message> where Message: Send + Sync + Clone + 'stat
 	}
 
 	/// Returns underlying io service.
-	pub fn io(&mut self) -> &mut IoService<NetworkIoMessage<Message>> {
+	pub fn io(&self) -> &IoService<NetworkIoMessage<Message>> {
-		&mut self.io_service
+		&self.io_service
 	}
 
 	/// Returns network statistics.
@@ -80,12 +80,37 @@ impl<Message> NetworkService<Message> where Message: Send + Sync + Clone + 'stat
 
 	/// Returns external url if available.
 	pub fn external_url(&self) -> Option<String> {
-		self.host.external_url()
+		let host = self.host.read().unwrap();
+		host.as_ref().and_then(|h| h.external_url())
 	}
 
 	/// Returns external url if available.
-	pub fn local_url(&self) -> String {
+	pub fn local_url(&self) -> Option<String> {
-		self.host.local_url()
+		let host = self.host.read().unwrap();
+		host.as_ref().map(|h| h.local_url())
+	}
+
+	/// Start network IO
+	pub fn start(&self) -> Result<(), UtilError> {
+		let mut host = self.host.write().unwrap();
+		if host.is_none() {
+			let h = Arc::new(try!(Host::new(self.config.clone(), self.stats.clone())));
+			try!(self.io_service.register_handler(h.clone()));
+			*host = Some(h);
+		}
+		Ok(())
+	}
+
+	/// Stop network IO
+	pub fn stop(&self) -> Result<(), UtilError> {
+		let mut host = self.host.write().unwrap();
+		if let Some(ref host) = *host {
+			info!("Unregistering handler");
+			let io = IoContext::new(self.io_service.channel(), 0); //TODO: take token id from host
+			host.stop(&io);
+		}
+		*host = None;
+		Ok(())
 	}
 }
 

util/src/network/stats.rs

@@ -65,7 +65,7 @@ impl NetworkStats {
 		self.sessions.load(Ordering::Relaxed)
 	}
 
-	#[cfg(test)]
+	/// Create a new empty instance.
 	pub fn new() -> NetworkStats {
 		NetworkStats {
 			recv: AtomicUsize::new(0),