Merge branch 'tx_queue_integration' into tx_queue_rpc

2016-03-08 10:17:01 +01:00 · 2016-03-08 10:17:01 +01:00 · 1184679d23
commit 1184679d23
parent c49258e866 f973610b38
13 changed files with 456 additions and 221 deletions
--- a/ethcore/src/client.rs
+++ b/ethcore/src/client.rs
@ -87,6 +87,8 @@ pub struct ClientConfig {
 	pub blockchain: BlockChainConfig,
 	/// Prefer journal rather than archive.
 	pub prefer_journal: bool,
+	/// The name of the client instance.
+	pub name: String,
 }

 impl Default for ClientConfig {
@ -95,6 +97,7 @@ impl Default for ClientConfig {
 			queue: Default::default(),
 			blockchain: Default::default(),
 			prefer_journal: false,
+			name: Default::default(),
 		}
 	}
 }
@ -193,6 +196,8 @@ pub struct ClientReport {
 	pub transactions_applied: usize,
 	/// How much gas has been processed so far.
 	pub gas_processed: U256,
+	/// Memory used by state DB
+	pub state_db_mem: usize,
 }

 impl ClientReport {
@ -225,7 +230,7 @@ pub struct Client<V = CanonVerifier> where V: Verifier {
 }

 const HISTORY: u64 = 1000;
-const CLIENT_DB_VER_STR: &'static str = "4.0";
+const CLIENT_DB_VER_STR: &'static str = "5.1";

 impl Client<CanonVerifier> {
 	/// Create a new client with given spec and DB path.
@ -439,7 +444,9 @@ impl<V> Client<V> where V: Verifier {

 	/// Get the report.
 	pub fn report(&self) -> ClientReport {
-		self.report.read().unwrap().clone()
+		let mut report = self.report.read().unwrap().clone();
+		report.state_db_mem = self.state_db.lock().unwrap().mem_used();
+		report
 	}

 	/// Tick the client.
--- a/parity/main.rs
+++ b/parity/main.rs
@ -53,6 +53,16 @@ use docopt::Docopt;
 use daemonize::Daemonize;
 use number_prefix::{binary_prefix, Standalone, Prefixed};

+fn die_with_message(msg: &str) -> ! {
+	println!("ERROR: {}", msg);
+	exit(1);
+}
+
+#[macro_export]
+macro_rules! die {
+	($($arg:tt)*) => (die_with_message(&format!("{}", format_args!($($arg)*))));
+}
+
 const USAGE: &'static str = r#"
 Parity. Ethereum Client.
  By Wood/Paronyan/Kotewicz/Drwięga/Volf.
@ -62,13 +72,16 @@ Usage:
  parity daemon <pid-file> [options] [ --no-bootstrap | <enode>... ]
  parity [options] [ --no-bootstrap | <enode>... ]

-Options:
+Protocol Options:
  --chain CHAIN            Specify the blockchain type. CHAIN may be either a JSON chain specification file
-                           or frontier, mainnet, morden, or testnet [default: frontier].
+                           or olympic, frontier, homestead, mainnet, morden, or testnet [default: homestead].
+  --testnet                Equivalent to --chain testnet (geth-compatible).
+  --networkid INDEX        Override the network identifier from the chain we are on.
  --archive                Client should not prune the state/storage trie.
-  -d --db-path PATH        Specify the database & configuration directory path [default: $HOME/.parity]
-  --keys-path PATH         Specify the path for JSON key files to be found [default: $HOME/.web3/keys]
+  -d --datadir PATH        Specify the database & configuration directory path [default: $HOME/.parity]
+  --identity NAME          Specify your node's name.

+Networking Options:
  --no-bootstrap           Don't bother trying to connect to any nodes initially.
  --listen-address URL     Specify the IP/port on which to listen for peers [default: 0.0.0.0:30304].
  --public-address URL     Specify the IP/port on which peers may connect.
@ -78,18 +91,32 @@ Options:
  --no-upnp                Disable trying to figure out the correct public adderss over UPnP.
  --node-key KEY           Specify node secret key, either as 64-character hex string or input to SHA3 operation.

+API and Console Options:
+  -j --jsonrpc             Enable the JSON-RPC API sever.
+  --jsonrpc-addr HOST      Specify the hostname portion of the JSONRPC API server [default: 127.0.0.1].
+  --jsonrpc-port PORT      Specify the port portion of the JSONRPC API server [default: 8545].
+  --jsonrpc-cors URL       Specify CORS header for JSON-RPC API responses [default: null].
+  --jsonrpc-apis APIS      Specify the APIs available through the JSONRPC interface. APIS is a comma-delimited
+                           list of API name. Possible name are web3, eth and net. [default: web3,eth,net].
+  --rpc                    Equivalent to --jsonrpc (geth-compatible).
+  --rpcaddr HOST           Equivalent to --jsonrpc-addr HOST (geth-compatible).
+  --rpcport PORT           Equivalent to --jsonrpc-port PORT (geth-compatible).
+  --rpcapi APIS            Equivalent to --jsonrpc-apis APIS (geth-compatible).
+  --rpccorsdomain URL      Equivalent to --jsonrpc-cors URL (geth-compatible).
+
+Sealing/Mining Options:
+  --author ADDRESS         Specify the block author (aka "coinbase") address for sending block rewards
+                           from sealed blocks [default: 0037a6b811ffeb6e072da21179d11b1406371c63].
+  --extradata STRING      Specify a custom extra-data for authored blocks, no more than 32 characters.
+
+Memory Footprint Options:
  --cache-pref-size BYTES  Specify the prefered size of the blockchain cache in bytes [default: 16384].
  --cache-max-size BYTES   Specify the maximum size of the blockchain cache in bytes [default: 262144].
  --queue-max-size BYTES   Specify the maximum size of memory to use for block queue [default: 52428800].
+  --cache MEGABYTES        Set total amount of cache to use for the entire system, mutually exclusive with 
+                           other cache options (geth-compatible).

-  -j --jsonrpc             Enable the JSON-RPC API sever.
-  --jsonrpc-url URL        Specify URL for JSON-RPC API server [default: 127.0.0.1:8545].
-  --jsonrpc-cors URL       Specify CORS header for JSON-RPC API responses [default: null].
-
-  --author ADDRESS         Specify the block author (aka "coinbase") address for sending block rewards
-                           from sealed blocks [default: 0037a6b811ffeb6e072da21179d11b1406371c63].
-  --extra-data STRING      Specify a custom extra-data for authored blocks, no more than 32 characters.
-
+Miscellaneous Options:
  -l --logging LOGGING     Specify the logging level.
  -v --version             Show information about version.
  -h --help                Show this screen.
@ -101,14 +128,18 @@ struct Args {
 	arg_pid_file: String,
 	arg_enode: Vec<String>,
 	flag_chain: String,
+	flag_testnet: bool,
 	flag_db_path: String,
+	flag_networkid: Option<String>,
+	flag_identity: String,
+	flag_cache: Option<usize>,
 	flag_keys_path: String,
 	flag_archive: bool,
 	flag_no_bootstrap: bool,
 	flag_listen_address: String,
 	flag_public_address: Option<String>,
 	flag_address: Option<String>,
-	flag_peers: u32,
+	flag_peers: usize,
 	flag_no_discovery: bool,
 	flag_no_upnp: bool,
 	flag_node_key: Option<String>,
@ -116,8 +147,15 @@ struct Args {
 	flag_cache_max_size: usize,
 	flag_queue_max_size: usize,
 	flag_jsonrpc: bool,
-	flag_jsonrpc_url: String,
+	flag_jsonrpc_addr: String,
+	flag_jsonrpc_port: u16,
 	flag_jsonrpc_cors: String,
+	flag_jsonrpc_apis: String,
+	flag_rpc: bool,
+	flag_rpcaddr: Option<String>,
+	flag_rpcport: Option<u16>,
+	flag_rpccorsdomain: Option<String>,
+	flag_rpcapi: Option<String>,
 	flag_logging: Option<String>,
 	flag_version: bool,
 	flag_author: String,
@ -151,14 +189,23 @@ fn setup_log(init: &Option<String>) {
 }

 #[cfg(feature = "rpc")]
-fn setup_rpc_server(client: Arc<Client>, sync: Arc<EthSync>, url: &str, cors_domain: &str) {
+fn setup_rpc_server(client: Arc<Client>, sync: Arc<EthSync>, url: &str, cors_domain: &str, apis: Vec<&str>) {
 	use rpc::v1::*;

 	let mut server = rpc::HttpServer::new(1);
-	server.add_delegate(Web3Client::new().to_delegate());
+	for api in apis.into_iter() {
+		match api {
+			"web3" => server.add_delegate(Web3Client::new().to_delegate()),
+			"net" => server.add_delegate(NetClient::new(&sync).to_delegate()),
+			"eth" => {
 				server.add_delegate(EthClient::new(&client, &sync).to_delegate());
 				server.add_delegate(EthFilterClient::new(&client).to_delegate());
-	server.add_delegate(NetClient::new(&sync).to_delegate());
+			}
+			_ => {
+				die!("{}: Invalid API name to be enabled.", api);
+			}
+		}
+	}
 	server.start_async(url, cors_domain);
 }

@ -179,16 +226,6 @@ By Wood/Paronyan/Kotewicz/Drwięga/Volf.\
 ", version());
 }

-fn die_with_message(msg: &str) -> ! {
-	println!("ERROR: {}", msg);
-	exit(1);
-}
-
-#[macro_export]
-macro_rules! die {
-	($($arg:tt)*) => (die_with_message(&format!("{}", format_args!($($arg)*))));
-}
-
 struct Configuration {
 	args: Args
 }
@ -221,8 +258,11 @@ impl Configuration {
 	}

 	fn spec(&self) -> Spec {
+		if self.args.flag_testnet {
+			return ethereum::new_morden();
+		}
 		match self.args.flag_chain.as_ref() {
-			"frontier" | "mainnet" => ethereum::new_frontier(),
+			"frontier" | "homestead" | "mainnet" => ethereum::new_frontier(),
 			"morden" | "testnet" => ethereum::new_morden(),
 			"olympic" => ethereum::new_olympic(),
 			f => Spec::from_json_utf8(contents(f).unwrap_or_else(|_| die!("{}: Couldn't read chain specification file. Sure it exists?", f)).as_ref()),
@ -276,7 +316,7 @@ impl Configuration {
 		ret.public_address = public;
 		ret.use_secret = self.args.flag_node_key.as_ref().map(|s| Secret::from_str(&s).unwrap_or_else(|_| s.sha3()));
 		ret.discovery_enabled = !self.args.flag_no_discovery;
-		ret.ideal_peers = self.args.flag_peers;
+		ret.ideal_peers = self.args.flag_peers as u32;
 		let mut net_path = PathBuf::from(&self.path());
 		net_path.push("network");
 		ret.config_path = Some(net_path.to_str().unwrap().to_owned());
@ -307,13 +347,22 @@ impl Configuration {
 		let spec = self.spec();
 		let net_settings = self.net_settings(&spec);
 		let mut sync_config = SyncConfig::default();
-		sync_config.network_id = spec.network_id();
+		sync_config.network_id = self.args.flag_networkid.as_ref().map(|id| U256::from_str(id).unwrap_or_else(|_| die!("{}: Invalid index given with --networkid", id))).unwrap_or(spec.network_id());

 		// Build client
 		let mut client_config = ClientConfig::default();
+		match self.args.flag_cache {
+			Some(mb) => {
+				client_config.blockchain.max_cache_size = mb * 1024 * 1024;
+				client_config.blockchain.pref_cache_size = client_config.blockchain.max_cache_size / 2;
+			}
+			None => {
 				client_config.blockchain.pref_cache_size = self.args.flag_cache_pref_size;
 				client_config.blockchain.max_cache_size = self.args.flag_cache_max_size;
+			}
+		}
 		client_config.prefer_journal = !self.args.flag_archive;
+		client_config.name = self.args.flag_identity.clone();
 		client_config.queue.max_mem_use = self.args.flag_queue_max_size;
 		let mut service = ClientService::start(client_config, spec, net_settings, &Path::new(&self.path())).unwrap();
 		let client = service.client().clone();
@ -324,9 +373,16 @@ impl Configuration {
 		let sync = EthSync::register(service.network(), sync_config, client);

 		// Setup rpc
-		if self.args.flag_jsonrpc {
-			setup_rpc_server(service.client(), sync.clone(), &self.args.flag_jsonrpc_url, &self.args.flag_jsonrpc_cors);
-			SocketAddr::from_str(&self.args.flag_jsonrpc_url).unwrap_or_else(|_|die!("{}: Invalid JSONRPC listen address given with --jsonrpc-url. Should be of the form 'IP:port'.", self.args.flag_jsonrpc_url));
+		if self.args.flag_jsonrpc || self.args.flag_rpc {
+			let url = format!("{}:{}",
+				self.args.flag_rpcaddr.as_ref().unwrap_or(&self.args.flag_jsonrpc_addr),
+				self.args.flag_rpcport.unwrap_or(self.args.flag_jsonrpc_port)
+			);
+			SocketAddr::from_str(&url).unwrap_or_else(|_|die!("{}: Invalid JSONRPC listen host/port given.", url));
+			let cors = self.args.flag_rpccorsdomain.as_ref().unwrap_or(&self.args.flag_jsonrpc_cors);
+			// TODO: use this as the API list.
+			let apis = self.args.flag_rpcapi.as_ref().unwrap_or(&self.args.flag_jsonrpc_apis);
+			setup_rpc_server(service.client(), sync.clone(), &url, cors, apis.split(",").collect());
 		}

 		// Register IO handler
@ -395,7 +451,7 @@ impl Informant {
 		let sync_info = sync.status();

 		if let (_, _, &Some(ref last_report)) = (self.chain_info.read().unwrap().deref(), self.cache_info.read().unwrap().deref(), self.report.read().unwrap().deref()) {
-			println!("[ #{} {} ]---[ {} blk/s | {} tx/s | {} gas/s  //··· {}/{} peers, #{}, {}+{} queued ···// mem: {} chain, {} queue, {} sync ]",
+			println!("[ #{} {} ]---[ {} blk/s | {} tx/s | {} gas/s  //··· {}/{} peers, #{}, {}+{} queued ···// mem: {} db, {} chain, {} queue, {} sync ]",
 				chain_info.best_block_number,
 				chain_info.best_block_hash,
 				(report.blocks_imported - last_report.blocks_imported) / dur,
@ -408,6 +464,7 @@ impl Informant {
 				queue_info.unverified_queue_size,
 				queue_info.verified_queue_size,

+				Informant::format_bytes(report.state_db_mem),
 				Informant::format_bytes(cache_info.total()),
 				Informant::format_bytes(queue_info.mem_used),
 				Informant::format_bytes(sync_info.mem_used),
--- a/rpc/src/v1/impls/eth.rs
+++ b/rpc/src/v1/impls/eth.rs
@ -323,7 +323,8 @@ impl EthFilter for EthFilterClient {
 					None => Ok(Value::Array(vec![] as Vec<Value>)),
 					Some(info) => match info.filter {
 						PollFilter::Block => {
-							let current_number = client.chain_info().best_block_number;
+							// + 1, cause we want to return hashes including current block hash.
+							let current_number = client.chain_info().best_block_number + 1;
 							let hashes = (info.block_number..current_number).into_iter()
 								.map(BlockId::Number)
 								.filter_map(|id| client.block_hash(id))
--- a/sync/src/chain.rs
+++ b/sync/src/chain.rs
@ -209,7 +209,7 @@ pub struct ChainSync {
 	/// True if common block for our and remote chain has been found
 	have_common_block: bool,
 	/// Last propagated block number
-	last_send_block_number: BlockNumber,
+	last_sent_block_number: BlockNumber,
 	/// Max blocks to download ahead
 	max_download_ahead_blocks: usize,
 	/// Network ID
@ -238,7 +238,7 @@ impl ChainSync {
 			last_imported_hash: None,
 			syncing_difficulty: U256::from(0u64),
 			have_common_block: false,
-			last_send_block_number: 0,
+			last_sent_block_number: 0,
 			max_download_ahead_blocks: max(MAX_HEADERS_TO_REQUEST, config.max_download_ahead_blocks),
 			network_id: config.network_id,
 			transaction_queue: Mutex::new(TransactionQueue::new()),
@ -910,9 +910,8 @@ impl ChainSync {
 		}
 		match sync.send(peer_id, packet_id, packet) {
 			Err(e) => {
-				warn!(target:"sync", "Error sending request: {:?}", e);
+				debug!(target:"sync", "Error sending request: {:?}", e);
 				sync.disable_peer(peer_id);
-				self.on_peer_aborting(sync, peer_id);
 			}
 			Ok(_) => {
 				let mut peer = self.peers.get_mut(&peer_id).unwrap();
@ -925,9 +924,8 @@ impl ChainSync {
 	/// Generic packet sender
 	fn send_packet(&mut self, sync: &mut SyncIo, peer_id: PeerId, packet_id: PacketId, packet: Bytes) {
 		if let Err(e) = sync.send(peer_id, packet_id, packet) {
-			warn!(target:"sync", "Error sending packet: {:?}", e);
+			debug!(target:"sync", "Error sending packet: {:?}", e);
 			sync.disable_peer(peer_id);
-			self.on_peer_aborting(sync, peer_id);
 		}
 	}
 	/// Called when peer sends us new transactions
@ -1251,26 +1249,25 @@ impl ChainSync {
 		sent
 	}

+	fn propagate_latest_blocks(&mut self, io: &mut SyncIo) {
+		let chain_info = io.chain().chain_info();
+		if (((chain_info.best_block_number as i64) - (self.last_sent_block_number as i64)).abs() as BlockNumber) < MAX_PEER_LAG_PROPAGATION {
+			let blocks = self.propagate_blocks(&chain_info, io);
+			let hashes = self.propagate_new_hashes(&chain_info, io);
+			if blocks != 0 || hashes != 0 {
+				trace!(target: "sync", "Sent latest {} blocks and {} hashes to peers.", blocks, hashes);
+			}
+		}
+		self.last_sent_block_number = chain_info.best_block_number;
+	}
+
 	/// Maintain other peers. Send out any new blocks and transactions
 	pub fn maintain_sync(&mut self, io: &mut SyncIo) {
 		self.check_resume(io);
 	}

-	/// should be called once chain has new block, triggers the latest block propagation
-	pub fn chain_blocks_verified(&mut self, io: &mut SyncIo) {
-		let chain = io.chain().chain_info();
-		if (((chain.best_block_number as i64) - (self.last_send_block_number as i64)).abs() as BlockNumber) < MAX_PEER_LAG_PROPAGATION {
-			let blocks = self.propagate_blocks(&chain, io);
-			let hashes = self.propagate_new_hashes(&chain, io);
-			if blocks != 0 || hashes != 0 {
-				trace!(target: "sync", "Sent latest {} blocks and {} hashes to peers.", blocks, hashes);
-			}
-		}
-		self.last_send_block_number = chain.best_block_number;
-	}
-
-	/// called when block is imported to chain, updates transactions queue
-	pub fn chain_new_blocks(&mut self, io: &SyncIo, good: &[H256], bad: &[H256], _retracted: &[H256]) {
+	/// called when block is imported to chain, updates transactions queue and propagates the blocks
+	pub fn chain_new_blocks(&mut self, io: &mut SyncIo, good: &[H256], bad: &[H256], _retracted: &[H256]) {
 		fn fetch_transactions(chain: &BlockChainClient, hash: &H256) -> Vec<SignedTransaction> {
 			let block = chain
 				.block(BlockId::Hash(hash.clone()))
@ -1281,6 +1278,7 @@ impl ChainSync {
 		}


+		{
 			let chain = io.chain();
 			let good = good.par_iter().map(|h| fetch_transactions(chain, h));
 			let bad = bad.par_iter().map(|h| fetch_transactions(chain, h));
@ -1299,6 +1297,12 @@ impl ChainSync {
 				transaction_queue.add_all(txs, |a| chain.nonce(a));
 			});
 		}
+
+		// Propagate latests blocks
+		self.propagate_latest_blocks(io);
+		// TODO [todr] propagate transactions?
+	}
+
 }

 #[cfg(test)]
@ -1637,13 +1641,13 @@ mod tests {
 		let retracted_blocks = vec![client.block_hash_delta_minus(1)];

 		let mut queue = VecDeque::new();
-		let io = TestIo::new(&mut client, &mut queue, None);
+		let mut io = TestIo::new(&mut client, &mut queue, None);

 		// when
-		sync.chain_new_blocks(&io, &[], &good_blocks, &[]);
+		sync.chain_new_blocks(&mut io, &[], &good_blocks, &[]);
 		assert_eq!(sync.transaction_queue.lock().unwrap().status().future, 0);
 		assert_eq!(sync.transaction_queue.lock().unwrap().status().pending, 1);
-		sync.chain_new_blocks(&io, &good_blocks, &retracted_blocks, &[]);
+		sync.chain_new_blocks(&mut io, &good_blocks, &retracted_blocks, &[]);

 		// then
 		let status = sync.transaction_queue.lock().unwrap().status();
--- a/sync/src/lib.rs
+++ b/sync/src/lib.rs
@ -154,13 +154,11 @@ impl NetworkProtocolHandler<SyncMessage> for EthSync {

 	fn message(&self, io: &NetworkContext<SyncMessage>, message: &SyncMessage) {
 		match *message {
-			SyncMessage::BlockVerified => {
-				self.sync.write().unwrap().chain_blocks_verified(&mut NetSyncIo::new(io, self.chain.deref()));
-			},
 			SyncMessage::NewChainBlocks { ref good, ref bad, ref retracted } => {
-				let sync_io = NetSyncIo::new(io, self.chain.deref());
-				self.sync.write().unwrap().chain_new_blocks(&sync_io, good, bad, retracted);
-			}
+				let mut sync_io = NetSyncIo::new(io, self.chain.deref());
+				self.sync.write().unwrap().chain_new_blocks(&mut sync_io, good, bad, retracted);
+			},
+			_ => {/* Ignore other messages */},
 		}
 	}
 }
--- a/sync/src/tests/chain.rs
+++ b/sync/src/tests/chain.rs
@ -129,8 +129,8 @@ fn propagate_hashes() {

 	net.peer_mut(0).chain.add_blocks(10, EachBlockWith::Uncle);
 	net.sync();
-	net.trigger_block_verified(0); //first event just sets the marker
-	net.trigger_block_verified(0);
+	net.trigger_chain_new_blocks(0); //first event just sets the marker
+	net.trigger_chain_new_blocks(0);

 	// 5 peers to sync
 	assert_eq!(5, net.peer(0).queue.len());
@ -154,8 +154,8 @@ fn propagate_blocks() {
 	net.sync();

 	net.peer_mut(0).chain.add_blocks(10, EachBlockWith::Uncle);
-	net.trigger_block_verified(0); //first event just sets the marker
-	net.trigger_block_verified(0);
+	net.trigger_chain_new_blocks(0); //first event just sets the marker
+	net.trigger_chain_new_blocks(0);

 	assert!(!net.peer(0).queue.is_empty());
 	// NEW_BLOCK_PACKET
--- a/sync/src/tests/helpers.rs
+++ b/sync/src/tests/helpers.rs
@ -455,8 +455,8 @@ impl TestNet {
 		self.peers.iter().all(|p| p.queue.is_empty())
 	}

-	pub fn trigger_block_verified(&mut self, peer_id: usize) {
+	pub fn trigger_chain_new_blocks(&mut self, peer_id: usize) {
 		let mut peer = self.peer_mut(peer_id);
-		peer.sync.chain_blocks_verified(&mut TestIo::new(&mut peer.chain, &mut peer.queue, None));
+		peer.sync.chain_new_blocks(&mut TestIo::new(&mut peer.chain, &mut peer.queue, None), &[], &[], &[]);
 	}
 }
--- a/util/src/journaldb.rs
+++ b/util/src/journaldb.rs
@ -25,10 +25,7 @@ use kvdb::{Database, DBTransaction, DatabaseConfig};
 use std::env;

 /// Implementation of the HashDB trait for a disk-backed database with a memory overlay
-/// and, possibly, latent-removal semantics.
-///
-/// If `counters` is `None`, then it behaves exactly like OverlayDB. If not it behaves
-/// differently:
+/// and latent-removal semantics.
 ///
 /// Like OverlayDB, there is a memory overlay; `commit()` must be called in order to 
 /// write operations out to disk. Unlike OverlayDB, `remove()` operations do not take effect
@ -60,7 +57,6 @@ const DB_VERSION_NO_JOURNAL : u32 = 3 + 256;
 const PADDING : [u8; 10] = [ 0u8; 10 ];

 impl JournalDB {
-
 	/// Create a new instance from file
 	pub fn new(path: &str) -> JournalDB {
 		Self::from_prefs(path, true)
@ -149,6 +145,87 @@ impl JournalDB {
 		Ok(ret as u32)
 	}

+	fn morph_key(key: &H256, index: u8) -> Bytes {
+		let mut ret = key.bytes().to_owned();
+		ret.push(index);
+		ret
+	}
+
+	// The next three are valid only as long as there is an insert operation of `key` in the journal.
+	fn set_already_in(batch: &DBTransaction, key: &H256) { batch.put(&Self::morph_key(key, 0), &[1u8]).expect("Low-level database error. Some issue with your hard disk?"); }
+	fn reset_already_in(batch: &DBTransaction, key: &H256) { batch.delete(&Self::morph_key(key, 0)).expect("Low-level database error. Some issue with your hard disk?"); }
+	fn is_already_in(backing: &Database, key: &H256) -> bool {
+		backing.get(&Self::morph_key(key, 0)).expect("Low-level database error. Some issue with your hard disk?").is_some()
+	}
+
+	fn insert_keys(inserts: &Vec<(H256, Bytes)>, backing: &Database, counters: &mut HashMap<H256, i32>, batch: &DBTransaction) {
+		for &(ref h, ref d) in inserts {
+			if let Some(c) = counters.get_mut(h) {
+				// already counting. increment.
+				*c += 1;
+				continue;
+			}
+
+			// this is the first entry for this node in the journal.
+			if backing.get(&h.bytes()).expect("Low-level database error. Some issue with your hard disk?").is_some() {
+				// already in the backing DB. start counting, and remember it was already in.
+				Self::set_already_in(batch, &h);
+				counters.insert(h.clone(), 1);
+				continue;
+			}
+
+			// Gets removed when a key leaves the journal, so should never be set when we're placing a new key.
+			//Self::reset_already_in(&h);
+			assert!(!Self::is_already_in(backing, &h));
+			batch.put(&h.bytes(), d).expect("Low-level database error. Some issue with your hard disk?");
+		}
+	}
+
+	fn replay_keys(inserts: &Vec<H256>, backing: &Database, counters: &mut HashMap<H256, i32>) {
+		trace!("replay_keys: inserts={:?}, counters={:?}", inserts, counters);
+		for h in inserts {
+			if let Some(c) = counters.get_mut(h) {
+				// already counting. increment.
+				*c += 1;
+				continue;
+			}
+
+			// this is the first entry for this node in the journal.
+			// it is initialised to 1 if it was already in.
+			if Self::is_already_in(backing, h) {
+				trace!("replace_keys: Key {} was already in!", h);
+				counters.insert(h.clone(), 1);
+			}
+		}
+		trace!("replay_keys: (end) counters={:?}", counters);
+	}
+
+	fn kill_keys(deletes: Vec<H256>, counters: &mut HashMap<H256, i32>, batch: &DBTransaction) {
+		for h in deletes.into_iter() {
+			let mut n: Option<i32> = None;
+			if let Some(c) = counters.get_mut(&h) {
+				if *c > 1 {
+					*c -= 1;
+					continue;
+				} else {
+					n = Some(*c);
+				}
+			}
+			match &n {
+				&Some(i) if i == 1 => {
+					counters.remove(&h);
+					Self::reset_already_in(batch, &h);
+				}
+				&None => {
+					// Gets removed when moving from 1 to 0 additional refs. Should never be here at 0 additional refs.
+					//assert!(!Self::is_already_in(db, &h));
+					batch.delete(&h.bytes()).expect("Low-level database error. Some issue with your hard disk?");
+				}
+				_ => panic!("Invalid value in counters: {:?}", n),
+			}
+		}
+	}
+
 	/// Commit all recent insert operations and historical removals from the old era
 	/// to the backing database.
 	fn commit_with_counters(&mut self, now: u64, id: &H256, end: Option<(u64, H256)>) -> Result<u32, UtilError> {
@ -159,21 +236,42 @@ impl JournalDB {

 		// TODO: store reclaim_period.

-		// when we make a new commit, we journal the inserts and removes.
-		// for each end_era that we journaled that we are no passing by, 
-		// we remove all of its removes assuming it is canonical and all
-		// of its inserts otherwise.
+		// When we make a new commit, we make a journal of all blocks in the recent history and record
+		// all keys that were inserted and deleted. The journal is ordered by era; multiple commits can
+		// share the same era. This forms a data structure similar to a queue but whose items are tuples.
+		// By the time comes to remove a tuple from the queue (i.e. then the era passes from recent history
+		// into ancient history) then only one commit from the tuple is considered canonical. This commit
+		// is kept in the main backing database, whereas any others from the same era are reverted.
 		// 
-		// We also keep reference counters for each key inserted in the journal to handle 
-		// the following cases where key K must not be deleted from the DB when processing removals :
-		// Given H is the journal size in eras, 0 <= C <= H.
-		// Key K is removed in era A(N) and re-inserted in canonical era B(N + C).
-		// Key K is removed in era A(N) and re-inserted in non-canonical era B`(N + C).
-		// Key K is added in non-canonical era A'(N) canonical B(N + C).
+		// It is possible that a key, properly available in the backing database be deleted and re-inserted
+		// in the recent history queue, yet have both operations in commits that are eventually non-canonical.
+		// To avoid the original, and still required, key from being deleted, we maintain a reference count
+		// which includes an original key, if any.
+		// 
+		// The semantics of the `counter` are:
+		// insert key k:
+		//   counter already contains k: count += 1
+		//   counter doesn't contain k:
+		//     backing db contains k: count = 1
+		//     backing db doesn't contain k: insert into backing db, count = 0
+		// delete key k:
+		//   counter contains k (count is asserted to be non-zero): 
+		//     count > 1: counter -= 1
+		//     count == 1: remove counter
+		//     count == 0: remove key from backing db
+		//   counter doesn't contain k: remove key from backing db
+		//
+		// Practically, this means that for each commit block turning from recent to ancient we do the
+		// following:
+		// is_canonical:
+		//   inserts: Ignored (left alone in the backing database).
+		//   deletes: Enacted; however, recent history queue is checked for ongoing references. This is
+		//            reduced as a preference to deletion from the backing database.
+		// !is_canonical:
+		//   inserts: Reverted; however, recent history queue is checked for ongoing references. This is
+		//            reduced as a preference to deletion from the backing database.
+		//   deletes: Ignored (they were never inserted).
 		//
-		// The counter is encreased each time a key is inserted in the journal in the commit. The list of insertions
-		// is saved with the era record. When the era becomes end_era and goes out of journal the counter is decreased
-		// and the key is safe to delete.

 		// record new commit's details.
 		trace!("commit: #{} ({}), end era: {:?}", now, id, end);		
@ -183,36 +281,40 @@ impl JournalDB {
 			let mut index = 0usize;
 			let mut last;

-			while {
-				let record = try!(self.backing.get({
+			while try!(self.backing.get({
 				let mut r = RlpStream::new_list(3);
 				r.append(&now);
 				r.append(&index);
 				r.append(&&PADDING[..]);
 				last = r.drain();
 				&last
-				}));
-				match record {
-					Some(r) => {
-						assert!(&Rlp::new(&r).val_at::<H256>(0) != id);
-						true
-					},
-					None => false,
-				}
-			} {
+			})).is_some() {
 				index += 1;
 			}

+			let drained = self.overlay.drain();
+			let removes: Vec<H256> = drained
+				.iter()
+				.filter_map(|(ref k, &(_, ref c))| if *c < 0 {Some(k.clone())} else {None}).cloned()
+				.collect();
+			let inserts: Vec<(H256, Bytes)> = drained
+				.into_iter()
+				.filter_map(|(k, (v, r))| if r > 0 { assert!(r == 1); Some((k, v)) } else { assert!(r >= -1); None })
+				.collect();
+
 			let mut r = RlpStream::new_list(3);
-			let inserts: Vec<H256> = self.overlay.keys().iter().filter(|&(_, &c)| c > 0).map(|(key, _)| key.clone()).collect();
-			// Increase counter for each inserted key no matter if the block is canonical or not. 
-			for i in &inserts {
-				*counters.entry(i.clone()).or_insert(0) += 1;
-			}
-			let removes: Vec<H256> = self.overlay.keys().iter().filter(|&(_, &c)| c < 0).map(|(key, _)| key.clone()).collect();
 			r.append(id);
-			r.append(&inserts);
+
+			// Process the new inserts.
+			// We use the inserts for three things. For each:
+			// - we place into the backing DB or increment the counter if already in;
+			// - we note in the backing db that it was already in;
+			// - we write the key into our journal for this block;
+
+			r.begin_list(inserts.len());
+			inserts.iter().foreach(|&(k, _)| {r.append(&k);});
 			r.append(&removes);
+			Self::insert_keys(&inserts, &self.backing, &mut counters, &batch);
 			try!(batch.put(&last, r.as_raw()));
 			try!(batch.put(&LATEST_ERA_KEY, &encode(&now)));
 		}
@ -221,8 +323,6 @@ impl JournalDB {
 		if let Some((end_era, canon_id)) = end {
 			let mut index = 0usize;
 			let mut last;
-			let mut to_remove: Vec<H256> = Vec::new();
-			let mut canon_inserts: Vec<H256> = Vec::new();
 			while let Some(rlp_data) = try!(self.backing.get({
 				let mut r = RlpStream::new_list(3);
 				r.append(&end_era);
@ -232,54 +332,19 @@ impl JournalDB {
 				&last
 			})) {
 				let rlp = Rlp::new(&rlp_data);
-				let mut inserts: Vec<H256> = rlp.val_at(1);
-				JournalDB::decrease_counters(&inserts, &mut counters);
+				let inserts: Vec<H256> = rlp.val_at(1);
+				let deletes: Vec<H256> = rlp.val_at(2);
 				// Collect keys to be removed. These are removed keys for canonical block, inserted for non-canonical
-				if canon_id == rlp.val_at(0) {
-					let mut canon_deletes: Vec<H256> = rlp.val_at(2);
-					trace!("Purging nodes deleted from canon: {:?}", canon_deletes);
-					to_remove.append(&mut canon_deletes);
-					canon_inserts = inserts;
-				}
-				else {
-					trace!("Purging nodes inserted in non-canon: {:?}", inserts);
-					to_remove.append(&mut inserts);
-				}
-				trace!("commit: Delete journal for time #{}.{}: {}, (canon was {}): {} entries", end_era, index, rlp.val_at::<H256>(0), canon_id, to_remove.len());
+				Self::kill_keys(if canon_id == rlp.val_at(0) {deletes} else {inserts}, &mut counters, &batch);
 				try!(batch.delete(&last));
 				index += 1;
 			}
-
-			let canon_inserts = canon_inserts.drain(..).collect::<HashSet<_>>();
-			// Purge removed keys if they are not referenced and not re-inserted in the canon commit
-			let mut deletes = 0;
-			trace!("Purging filtered nodes: {:?}", to_remove.iter().filter(|h| !counters.contains_key(h) && !canon_inserts.contains(h)).collect::<Vec<_>>());
-			for h in to_remove.iter().filter(|h| !counters.contains_key(h) && !canon_inserts.contains(h)) {
-				try!(batch.delete(&h));
-				deletes += 1;
-			}
-			trace!("Total nodes purged: {}", deletes);
+			trace!("JournalDB: delete journal for time #{}.{}, (canon was {})", end_era, index, canon_id);
 		}

-		// Commit overlay insertions
-		let ret = Self::batch_overlay_insertions(&mut self.overlay, &batch);
 		try!(self.backing.write(batch));
-		Ok(ret as u32)
-	}
-
-
-	// Decrease counters for given keys. Deletes obsolete counters
-	fn decrease_counters(keys: &[H256], counters: &mut HashMap<H256, i32>) {
-		for i in keys.iter() {
-			let delete_counter = {
-				let cnt = counters.get_mut(i).expect("Missing key counter");
-				*cnt -= 1;
-				*cnt == 0
-			};
-			if delete_counter {
-				counters.remove(i);
-			}
-		}
+//		trace!("JournalDB::commit() deleted {} nodes", deletes);
+		Ok(0)
 	}

 	fn payload(&self, key: &H256) -> Option<Bytes> {
@ -287,7 +352,7 @@ impl JournalDB {
 	}

 	fn read_counters(db: &Database) -> HashMap<H256, i32> {
-		let mut res = HashMap::new();
+		let mut counters = HashMap::new();
 		if let Some(val) = db.get(&LATEST_ERA_KEY).expect("Low-level database error.") {
 			let mut era = decode::<u64>(&val);
 			loop {
@ -299,11 +364,10 @@ impl JournalDB {
 					r.append(&&PADDING[..]);
 					&r.drain()
 				}).expect("Low-level database error.") {
+					trace!("read_counters: era={}, index={}", era, index);
 					let rlp = Rlp::new(&rlp_data);
-					let to_add: Vec<H256> = rlp.val_at(1);
-					for h in to_add {
-						*res.entry(h).or_insert(0) += 1;
-					}
+					let inserts: Vec<H256> = rlp.val_at(1);
+					Self::replay_keys(&inserts, db, &mut counters);
 					index += 1;
 				};
 				if index == 0 || era == 0 {
@ -312,10 +376,15 @@ impl JournalDB {
 				era -= 1;
 			}
 		}
-		trace!("Recovered {} counters", res.len());
-		res
+		trace!("Recovered {} counters", counters.len());
+		counters
+	}
+
+	/// Returns heap memory size used
+	pub fn mem_used(&self) -> usize {
+		self.overlay.mem_used() + match &self.counters { &Some(ref c) => c.read().unwrap().heap_size_of_children(), &None => 0 }
+ 	}
 }
-}

 impl HashDB for JournalDB {
 	fn keys(&self) -> HashMap<H256, i32> { 
@ -368,6 +437,28 @@ mod tests {
 	use super::*;
 	use hashdb::*;

+	#[test]
+	fn insert_same_in_fork() {
+		// history is 1
+		let mut jdb = JournalDB::new_temp();
+
+		let x = jdb.insert(b"X");
+		jdb.commit(1, &b"1".sha3(), None).unwrap();
+		jdb.commit(2, &b"2".sha3(), None).unwrap();
+		jdb.commit(3, &b"1002a".sha3(), Some((1, b"1".sha3()))).unwrap();
+		jdb.commit(4, &b"1003a".sha3(), Some((2, b"2".sha3()))).unwrap();
+
+		jdb.remove(&x);
+		jdb.commit(3, &b"1002b".sha3(), Some((1, b"1".sha3()))).unwrap();
+		let x = jdb.insert(b"X");
+		jdb.commit(4, &b"1003b".sha3(), Some((2, b"2".sha3()))).unwrap();
+
+		jdb.commit(5, &b"1004a".sha3(), Some((3, b"1002a".sha3()))).unwrap();
+		jdb.commit(6, &b"1005a".sha3(), Some((4, b"1003a".sha3()))).unwrap();
+
+		assert!(jdb.exists(&x));
+	}
+
 	#[test]
 	fn long_history() {
 		// history is 3
@ -488,15 +579,18 @@ mod tests {
 		assert!(jdb.exists(&foo));
 	}

+
 	#[test]
 	fn reopen() {
 		let mut dir = ::std::env::temp_dir();
 		dir.push(H32::random().hex());
+		let bar = H256::random();

 		let foo = {
 			let mut jdb = JournalDB::new(dir.to_str().unwrap());
 			// history is 1
 			let foo = jdb.insert(b"foo");
+			jdb.emplace(bar.clone(), b"bar".to_vec());
 			jdb.commit(0, &b"0".sha3(), None).unwrap();
 			foo
 		};
@ -510,8 +604,68 @@ mod tests {
 		{
 			let mut jdb = JournalDB::new(dir.to_str().unwrap());
 			assert!(jdb.exists(&foo));
+			assert!(jdb.exists(&bar));
 			jdb.commit(2, &b"2".sha3(), Some((1, b"1".sha3()))).unwrap();
 			assert!(!jdb.exists(&foo));
 		}
 	}
+
+	#[test]
+	fn reopen_remove() {
+		let mut dir = ::std::env::temp_dir();
+		dir.push(H32::random().hex());
+		let bar = H256::random();
+
+		let foo = {
+			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			// history is 1
+			let foo = jdb.insert(b"foo");
+			jdb.commit(0, &b"0".sha3(), None).unwrap();
+			jdb.commit(1, &b"1".sha3(), Some((0, b"0".sha3()))).unwrap();
+
+			// foo is ancient history.
+
+			jdb.insert(b"foo");
+			jdb.commit(2, &b"2".sha3(), Some((1, b"1".sha3()))).unwrap();
+			foo
+		};
+
+		{
+			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			jdb.remove(&foo);
+			jdb.commit(3, &b"3".sha3(), Some((2, b"2".sha3()))).unwrap();
+			assert!(jdb.exists(&foo));
+			jdb.remove(&foo);
+			jdb.commit(4, &b"4".sha3(), Some((3, b"3".sha3()))).unwrap();
+			jdb.commit(5, &b"5".sha3(), Some((4, b"4".sha3()))).unwrap();
+			assert!(!jdb.exists(&foo));
+		}
+	}
+	#[test]
+	fn reopen_fork() {
+		let mut dir = ::std::env::temp_dir();
+		dir.push(H32::random().hex());
+		let (foo, bar, baz) = {
+			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			// history is 1
+			let foo = jdb.insert(b"foo");
+			let bar = jdb.insert(b"bar");
+			jdb.commit(0, &b"0".sha3(), None).unwrap();
+			jdb.remove(&foo);
+			let baz = jdb.insert(b"baz");
+			jdb.commit(1, &b"1a".sha3(), Some((0, b"0".sha3()))).unwrap();
+
+			jdb.remove(&bar);
+			jdb.commit(1, &b"1b".sha3(), Some((0, b"0".sha3()))).unwrap();
+			(foo, bar, baz)
+		};
+
+		{
+			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			jdb.commit(2, &b"2b".sha3(), Some((1, b"1b".sha3()))).unwrap();
+			assert!(jdb.exists(&foo));
+			assert!(!jdb.exists(&baz));
+			assert!(!jdb.exists(&bar));
+		}
+	}
 }
--- a/util/src/memorydb.rs
+++ b/util/src/memorydb.rs
@ -21,6 +21,7 @@ use bytes::*;
 use rlp::*;
 use sha3::*;
 use hashdb::*;
+use heapsize::*;
 use std::mem;
 use std::collections::HashMap;

@ -143,6 +144,11 @@ impl MemoryDB {
 		}
 		self.raw(key).unwrap()
 	}
+
+	/// Returns the size of allocated heap memory
+	pub fn mem_used(&self) -> usize {
+		self.data.heap_size_of_children()
+	}
 }

 static NULL_RLP_STATIC: [u8; 1] = [0x80; 1];
--- a/util/src/network/connection.rs
+++ b/util/src/network/connection.rs
@ -190,25 +190,25 @@ impl Connection {

 	/// Register this connection with the IO event loop.
 	pub fn register_socket<Host: Handler>(&self, reg: Token, event_loop: &mut EventLoop<Host>) -> io::Result<()> {
-		trace!(target: "net", "connection register; token={:?}", reg);
+		trace!(target: "network", "connection register; token={:?}", reg);
 		if let Err(e) = event_loop.register(&self.socket, reg, self.interest, PollOpt::edge() | PollOpt::oneshot()) {
-			debug!("Failed to register {:?}, {:?}", reg, e);
+			trace!(target: "network", "Failed to register {:?}, {:?}", reg, e);
 		}
 		Ok(())
 	}

 	/// Update connection registration. Should be called at the end of the IO handler.
 	pub fn update_socket<Host: Handler>(&self, reg: Token, event_loop: &mut EventLoop<Host>) -> io::Result<()> {
-		trace!(target: "net", "connection reregister; token={:?}", reg);
+		trace!(target: "network", "connection reregister; token={:?}", reg);
 		event_loop.reregister( &self.socket, reg, self.interest, PollOpt::edge() | PollOpt::oneshot()).or_else(|e| {
-			debug!("Failed to reregister {:?}, {:?}", reg, e);
+			trace!(target: "network", "Failed to reregister {:?}, {:?}", reg, e);
 			Ok(())
 		})
 	}

 	/// Delete connection registration. Should be called at the end of the IO handler.
 	pub fn deregister_socket<Host: Handler>(&self, event_loop: &mut EventLoop<Host>) -> io::Result<()> {
-		trace!(target: "net", "connection deregister; token={:?}", self.token);
+		trace!(target: "network", "connection deregister; token={:?}", self.token);
 		event_loop.deregister(&self.socket).ok(); // ignore errors here
 		Ok(())
 	}
--- a/util/src/network/handshake.rs
+++ b/util/src/network/handshake.rs
@ -222,7 +222,7 @@ impl Handshake {

 	/// Parse, validate and confirm auth message
 	fn read_auth(&mut self, secret: &Secret, data: &[u8]) -> Result<(), UtilError> {
-		trace!(target:"net", "Received handshake auth from {:?}", self.connection.socket.peer_addr());
+		trace!(target:"network", "Received handshake auth from {:?}", self.connection.socket.peer_addr());
 		if data.len() != V4_AUTH_PACKET_SIZE {
 			debug!(target:"net", "Wrong auth packet size");
 			return Err(From::from(NetworkError::BadProtocol));
@ -253,7 +253,7 @@ impl Handshake {
 	}

 	fn read_auth_eip8(&mut self, secret: &Secret, data: &[u8]) -> Result<(), UtilError> {
-		trace!(target:"net", "Received EIP8 handshake auth from {:?}", self.connection.socket.peer_addr());
+		trace!(target:"network", "Received EIP8 handshake auth from {:?}", self.connection.socket.peer_addr());
 		self.auth_cipher.extend_from_slice(data);
 		let auth = try!(ecies::decrypt(secret, &self.auth_cipher[0..2], &self.auth_cipher[2..]));
 		let rlp = UntrustedRlp::new(&auth);
@ -268,7 +268,7 @@ impl Handshake {

 	/// Parse and validate ack message
 	fn read_ack(&mut self, secret: &Secret, data: &[u8]) -> Result<(), UtilError> {
-		trace!(target:"net", "Received handshake auth to {:?}", self.connection.socket.peer_addr());
+		trace!(target:"network", "Received handshake auth to {:?}", self.connection.socket.peer_addr());
 		if data.len() != V4_ACK_PACKET_SIZE {
 			debug!(target:"net", "Wrong ack packet size");
 			return Err(From::from(NetworkError::BadProtocol));
@ -296,7 +296,7 @@ impl Handshake {
 	}

 	fn read_ack_eip8(&mut self, secret: &Secret, data: &[u8]) -> Result<(), UtilError> {
-		trace!(target:"net", "Received EIP8 handshake auth from {:?}", self.connection.socket.peer_addr());
+		trace!(target:"network", "Received EIP8 handshake auth from {:?}", self.connection.socket.peer_addr());
 		self.ack_cipher.extend_from_slice(data);
 		let ack = try!(ecies::decrypt(secret, &self.ack_cipher[0..2], &self.ack_cipher[2..]));
 		let rlp = UntrustedRlp::new(&ack);
@ -309,7 +309,7 @@ impl Handshake {

 	/// Sends auth message
 	fn write_auth(&mut self, secret: &Secret, public: &Public) -> Result<(), UtilError> {
-		trace!(target:"net", "Sending handshake auth to {:?}", self.connection.socket.peer_addr());
+		trace!(target:"network", "Sending handshake auth to {:?}", self.connection.socket.peer_addr());
 		let mut data = [0u8; /*Signature::SIZE*/ 65 + /*H256::SIZE*/ 32 + /*Public::SIZE*/ 64 + /*H256::SIZE*/ 32 + 1]; //TODO: use associated constants
 		let len = data.len();
 		{
@ -336,7 +336,7 @@ impl Handshake {

 	/// Sends ack message
 	fn write_ack(&mut self) -> Result<(), UtilError> {
-		trace!(target:"net", "Sending handshake ack to {:?}", self.connection.socket.peer_addr());
+		trace!(target:"network", "Sending handshake ack to {:?}", self.connection.socket.peer_addr());
 		let mut data = [0u8; 1 + /*Public::SIZE*/ 64 + /*H256::SIZE*/ 32]; //TODO: use associated constants
 		let len = data.len();
 		{
@ -355,7 +355,7 @@ impl Handshake {

 	/// Sends EIP8 ack message
 	fn write_ack_eip8(&mut self) -> Result<(), UtilError> {
-		trace!(target:"net", "Sending EIP8 handshake ack to {:?}", self.connection.socket.peer_addr());
+		trace!(target:"network", "Sending EIP8 handshake ack to {:?}", self.connection.socket.peer_addr());
 		let mut rlp = RlpStream::new_list(3);
 		rlp.append(self.ecdhe.public());
 		rlp.append(&self.nonce);
--- a/util/src/network/host.rs
+++ b/util/src/network/host.rs
@ -170,29 +170,37 @@ pub struct NetworkContext<'s, Message> where Message: Send + Sync + Clone + 'sta
 	io: &'s IoContext<NetworkIoMessage<Message>>,
 	protocol: ProtocolId,
 	sessions: Arc<RwLock<Slab<SharedSession>>>,
-	session: Option<StreamToken>,
+	session: Option<SharedSession>,
+	session_id: Option<StreamToken>,
 }

 impl<'s, Message> NetworkContext<'s, Message> where Message: Send + Sync + Clone + 'static, {
 	/// Create a new network IO access point. Takes references to all the data that can be updated within the IO handler.
 	fn new(io: &'s IoContext<NetworkIoMessage<Message>>,
 		protocol: ProtocolId,
-		session: Option<StreamToken>, sessions: Arc<RwLock<Slab<SharedSession>>>) -> NetworkContext<'s, Message> {
+		session: Option<SharedSession>, sessions: Arc<RwLock<Slab<SharedSession>>>) -> NetworkContext<'s, Message> {
+		let id = session.as_ref().map(|s| s.lock().unwrap().token());
 		NetworkContext {
 			io: io,
 			protocol: protocol,
+			session_id: id,
 			session: session,
 			sessions: sessions,
 		}
 	}

+	fn resolve_session(&self, peer: PeerId) -> Option<SharedSession> {
+		match self.session_id {
+			Some(id) if id == peer => self.session.clone(),
+			_ => self.sessions.read().unwrap().get(peer).cloned(),
+		}
+	}
+
 	/// Send a packet over the network to another peer.
 	pub fn send(&self, peer: PeerId, packet_id: PacketId, data: Vec<u8>) -> Result<(), UtilError> {
-		let session = { self.sessions.read().unwrap().get(peer).cloned() };
+		let session = self.resolve_session(peer);
 		if let Some(session) = session {
-			session.lock().unwrap().deref_mut().send_packet(self.protocol, packet_id as u8, &data).unwrap_or_else(|e| {
-						warn!(target: "network", "Send error: {:?}", e);
-					}); //TODO: don't copy vector data
+			try!(session.lock().unwrap().deref_mut().send_packet(self.protocol, packet_id as u8, &data));
 			try!(self.io.update_registration(peer));
 		} else  {
 			trace!(target: "network", "Send: Peer no longer exist")
@ -200,14 +208,10 @@ impl<'s, Message> NetworkContext<'s, Message> where Message: Send + Sync + Clone
 		Ok(())
 	}

-	/// Respond to a current network message. Panics if no there is no packet in the context.
+	/// Respond to a current network message. Panics if no there is no packet in the context. If the session is expired returns nothing.
 	pub fn respond(&self, packet_id: PacketId, data: Vec<u8>) -> Result<(), UtilError> {
-		match self.session {
-			Some(session) => self.send(session, packet_id, data),
-			None => {
-				panic!("Respond: Session does not exist")
-			}
-		}
+		assert!(self.session.is_some(), "Respond called without network context");
+		self.send(self.session_id.unwrap(), packet_id, data)
 	}

 	/// Send an IO message
@ -215,7 +219,6 @@ impl<'s, Message> NetworkContext<'s, Message> where Message: Send + Sync + Clone
 		self.io.message(NetworkIoMessage::User(msg));
 	}

-
 	/// 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
@ -239,7 +242,7 @@ impl<'s, Message> NetworkContext<'s, Message> where Message: Send + Sync + Clone

 	/// Returns peer identification string
 	pub fn peer_info(&self, peer: PeerId) -> String {
-		let session = { self.sessions.read().unwrap().get(peer).cloned() };
+		let session = self.resolve_session(peer);
 		if let Some(session) = session {
 			return session.lock().unwrap().info.client_version.clone()
 		}
@ -624,7 +627,7 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 		let mut packet_data: Option<(ProtocolId, PacketId, Vec<u8>)> = None;
 		let mut kill = false;
 		let session = { self.sessions.read().unwrap().get(token).cloned() };
-		if let Some(session) = session {
+		if let Some(session) = session.clone() {
 			let mut s = session.lock().unwrap();
 			match s.readable(io, &self.info.read().unwrap()) {
 				Err(e) => {
@ -656,11 +659,11 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 		}
 		for p in ready_data {
 			let h = self.handlers.read().unwrap().get(p).unwrap().clone();
-			h.connected(&NetworkContext::new(io, p, Some(token), self.sessions.clone()), &token);
+			h.connected(&NetworkContext::new(io, p, session.clone(), self.sessions.clone()), &token);
 		}
 		if let Some((p, packet_id, data)) = packet_data {
 			let h = self.handlers.read().unwrap().get(p).unwrap().clone();
-			h.read(&NetworkContext::new(io, p, Some(token), self.sessions.clone()), &token, packet_id, &data[1..]);
+			h.read(&NetworkContext::new(io, p, session.clone(), self.sessions.clone()), &token, packet_id, &data[1..]);
 		}
 		io.update_registration(token).unwrap_or_else(|e| debug!(target: "network", "Token registration error: {:?}", e));
 	}
@ -718,6 +721,7 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 		let mut to_disconnect: Vec<ProtocolId> = Vec::new();
 		let mut failure_id = None;
 		let mut deregister = false;
+		let mut expired_session = None;
 		match token {
 			FIRST_HANDSHAKE ... LAST_HANDSHAKE => {
 				let handshakes = self.handshakes.write().unwrap();
@ -733,6 +737,7 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 			FIRST_SESSION ... LAST_SESSION => {
 				let sessions = self.sessions.write().unwrap();
 				if let Some(session) = sessions.get(token).cloned() {
+					expired_session = Some(session.clone());
 					let mut s = session.lock().unwrap();
 					if !s.expired() {
 						if s.is_ready() {
@ -757,7 +762,7 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 		}
 		for p in to_disconnect {
 			let h = self.handlers.read().unwrap().get(p).unwrap().clone();
-			h.disconnected(&NetworkContext::new(io, p, Some(token), self.sessions.clone()), &token);
+			h.disconnected(&NetworkContext::new(io, p, expired_session.clone(), self.sessions.clone()), &token);
 		}
 		if deregister {
 			io.deregister_stream(token).expect("Error deregistering stream");
--- a/util/src/network/session.rs
+++ b/util/src/network/session.rs
@ -213,6 +213,9 @@ impl Session {

 	/// Send a protocol packet to peer.
 	pub fn send_packet(&mut self, protocol: &str, packet_id: u8, data: &[u8]) -> Result<(), UtilError> {
+		if self.expired() {
+			return Err(From::from(NetworkError::Expired));
+		}
 		let mut i = 0usize;
 		while protocol != self.info.capabilities[i].protocol {
 			i += 1;
@ -351,15 +354,15 @@ impl Session {
 			offset += caps[i].packet_count;
 			i += 1;
 		}
-		trace!(target: "net", "Hello: {} v{} {} {:?}", client_version, protocol, id, caps);
+		trace!(target: "network", "Hello: {} v{} {} {:?}", client_version, protocol, id, caps);
 		self.info.client_version = client_version;
 		self.info.capabilities = caps;
 		if self.info.capabilities.is_empty() {
-			trace!("No common capabilities with peer.");
+			trace!(target: "network", "No common capabilities with peer.");
 			return Err(From::from(self.disconnect(DisconnectReason::UselessPeer)));
 		}
 		if protocol != host.protocol_version {
-			trace!("Peer protocol version mismatch: {}", protocol);
+			trace!(target: "network", "Peer protocol version mismatch: {}", protocol);
 			return Err(From::from(self.disconnect(DisconnectReason::UselessPeer)));
 		}
 		self.had_hello = true;