Merge branch 'master' into jg-external-dapps

2016-11-16 12:36:43 +01:00 · 2016-11-16 12:36:43 +01:00 · d14801f4ea
commit d14801f4ea
parent 68efa70977 df1fbf50d8
55 changed files with 8720 additions and 7653 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@ -1249,7 +1249,7 @@ dependencies = [
 [[package]]
 name = "parity-ui-precompiled"
 version = "1.4.0"
-source = "git+https://github.com/ethcore/js-precompiled.git#b4df3bd592651729716ec38577410f7c1e767007"
+source = "git+https://github.com/ethcore/js-precompiled.git#985a6d9cf9aa4621172fcb8e4bf6955f33d5e2a3"
 dependencies = [
 "parity-dapps-glue 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
--- a/ethcore/res/authority_round.json
+++ b/ethcore/res/authority_round.json
@ -0,0 +1,42 @@
+{
+	"name": "TestAuthorityRound",
+	"engine": {
+		"AuthorityRound": {
+			"params": {
+				"gasLimitBoundDivisor": "0x0400",
+				"stepDuration": "1",
+				"authorities" : [
+					"0x7d577a597b2742b498cb5cf0c26cdcd726d39e6e",
+					"0x82a978b3f5962a5b0957d9ee9eef472ee55b42f1"
+				]
+			}
+		}
+	},
+	"params": {
+		"accountStartNonce": "0x0",
+		"maximumExtraDataSize": "0x20",
+		"minGasLimit": "0x1388",
+		"networkID" : "0x69"
+	},
+	"genesis": {
+		"seal": {
+			"generic": {
+				"fields": 1,
+				"rlp": "0x11bbe8db4e347b4e8c937c1c8370e4b5ed33adb3db69cbdb7a38e1e50b1b82fa"
+			}
+		},
+		"difficulty": "0x20000",
+		"author": "0x0000000000000000000000000000000000000000",
+		"timestamp": "0x00",
+		"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
+		"extraData": "0x",
+		"gasLimit": "0x2fefd8"
+	},
+	"accounts": {
+		"0000000000000000000000000000000000000001": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
+		"0000000000000000000000000000000000000002": { "balance": "1", "nonce": "1048576", "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
+		"0000000000000000000000000000000000000003": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
+		"0000000000000000000000000000000000000004": { "balance": "1", "nonce": "1048576", "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
+		"9cce34f7ab185c7aba1b7c8140d620b4bda941d6": { "balance": "1606938044258990275541962092341162602522202993782792835301376", "nonce": "1048576" }
+	}
+}
--- a/ethcore/res/basic_authority.json
+++ b/ethcore/res/basic_authority.json
@ -1,5 +1,5 @@
 {
-	"name": "TestAuthority",
+	"name": "TestBasicAuthority",
 	"engine": {
 		"BasicAuthority": {
 			"params": {
--- a/ethcore/res/ethereum/frontier.json
+++ b/ethcore/res/ethereum/frontier.json
@ -131,10 +131,11 @@
 					"0x807640a13483f8ac783c557fcdf27be11ea4ac7a"
 				],
 				"eip150Transition": "0x259518",
-				"eip155Transition": "0x7fffffffffffffff",
-				"eip160Transition": "0x7fffffffffffffff",
-				"eip161abcTransition": "0x7fffffffffffffff",
-				"eip161dTransition": "0x7fffffffffffffff"
+				"eip155Transition": 2675000,
+				"eip160Transition": 2675000,
+				"eip161abcTransition": 2675000,
+				"eip161dTransition": 2675000,
+				"maxCodeSize": 24576
 			}
 		}
 	},
--- a/ethcore/res/ethereum/morden.json
+++ b/ethcore/res/ethereum/morden.json
@ -11,10 +11,10 @@
 				"registrar": "0x52dff57a8a1532e6afb3dc07e2af58bb9eb05b3d",
 				"homesteadTransition": "0x789b0",
 				"eip150Transition": "0x1b34d8",
-				"eip155Transition": "0x7fffffffffffffff",
-				"eip160Transition": "0x7fffffffffffffff",
-				"eip161abcTransition": "0x7fffffffffffffff",
-				"eip161dTransition": "0x7fffffffffffffff"
+				"eip155Transition": 1885000,
+				"eip160Transition": 1885000,
+				"eip161abcTransition": 1885000,
+				"eip161dTransition": 1885000
 			}
 		}
 	},
--- a/ethcore/src/client/client.rs
+++ b/ethcore/src/client/client.rs
@ -554,6 +554,7 @@ impl Client {

 	/// Import transactions from the IO queue
 	pub fn import_queued_transactions(&self, transactions: &[Bytes]) -> usize {
+		trace!(target: "external_tx", "Importing queued");
 		let _timer = PerfTimer::new("import_queued_transactions");
 		self.queue_transactions.fetch_sub(transactions.len(), AtomicOrdering::SeqCst);
 		let txs = transactions.iter().filter_map(|bytes| UntrustedRlp::new(bytes).as_val().ok()).collect();
@ -561,6 +562,11 @@ impl Client {
 		results.len()
 	}

+	/// Used by PoA to try sealing on period change.
+	pub fn update_sealing(&self) {
+		self.miner.update_sealing(self)
+	}
+
 	/// Attempt to get a copy of a specific block's final state.
 	///
 	/// This will not fail if given BlockID::Latest.
@ -1193,7 +1199,9 @@ impl BlockChainClient for Client {
 	}

 	fn queue_transactions(&self, transactions: Vec<Bytes>) {
-		if self.queue_transactions.load(AtomicOrdering::Relaxed) > MAX_TX_QUEUE_SIZE {
+		let queue_size = self.queue_transactions.load(AtomicOrdering::Relaxed);
+		trace!(target: "external_tx", "Queue size: {}", queue_size);
+		if queue_size > MAX_TX_QUEUE_SIZE {
 			debug!("Ignoring {} transactions: queue is full", transactions.len());
 		} else {
 			let len = transactions.len();
--- a/ethcore/src/client/test_client.rs
+++ b/ethcore/src/client/test_client.rs
@ -119,6 +119,16 @@ impl TestBlockChainClient {
 	/// Creates new test client with specified extra data for each block
 	pub fn new_with_extra_data(extra_data: Bytes) -> Self {
 		let spec = Spec::new_test();
+		TestBlockChainClient::new_with_spec_and_extra(spec, extra_data)
+	}
+
+	/// Create test client with custom spec.
+	pub fn new_with_spec(spec: Spec) -> Self {
+		TestBlockChainClient::new_with_spec_and_extra(spec, Bytes::new())
+	}
+
+	/// Create test client with custom spec and extra data.
+	pub fn new_with_spec_and_extra(spec: Spec, extra_data: Bytes) -> Self {
 		let mut client = TestBlockChainClient {
 			blocks: RwLock::new(HashMap::new()),
 			numbers: RwLock::new(HashMap::new()),
@ -315,7 +325,7 @@ pub fn get_temp_state_db() -> GuardedTempResult<StateDB> {

 impl MiningBlockChainClient for TestBlockChainClient {
 	fn latest_schedule(&self) -> Schedule {
-		Schedule::new_post_eip150(true, true, true)
+		Schedule::new_post_eip150(24576, true, true, true)
 	}

 	fn prepare_open_block(&self, author: Address, gas_range_target: (U256, U256), extra_data: Bytes) -> OpenBlock {
--- a/ethcore/src/engines/authority_round.rs
+++ b/ethcore/src/engines/authority_round.rs
@ -0,0 +1,429 @@
+// Copyright 2015, 2016 Ethcore (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! A blockchain engine that supports a non-instant BFT proof-of-authority.
+
+use std::sync::atomic::{AtomicUsize, AtomicBool, Ordering as AtomicOrdering};
+use std::sync::Weak;
+use std::time::{UNIX_EPOCH, Duration};
+use util::*;
+use ethkey::{verify_address, Signature};
+use rlp::{UntrustedRlp, View, encode};
+use account_provider::AccountProvider;
+use block::*;
+use spec::CommonParams;
+use engines::Engine;
+use header::Header;
+use error::{Error, BlockError};
+use evm::Schedule;
+use ethjson;
+use io::{IoContext, IoHandler, TimerToken, IoService, IoChannel};
+use service::ClientIoMessage;
+use transaction::SignedTransaction;
+use env_info::EnvInfo;
+use builtin::Builtin;
+
+/// `AuthorityRound` params.
+#[derive(Debug, PartialEq)]
+pub struct AuthorityRoundParams {
+	/// Gas limit divisor.
+	pub gas_limit_bound_divisor: U256,
+	/// Time to wait before next block or authority switching.
+	pub step_duration: Duration,
+	/// Valid authorities.
+	pub authorities: Vec<Address>,
+	/// Number of authorities.
+	pub authority_n: usize,
+}
+
+impl From<ethjson::spec::AuthorityRoundParams> for AuthorityRoundParams {
+	fn from(p: ethjson::spec::AuthorityRoundParams) -> Self {
+		AuthorityRoundParams {
+			gas_limit_bound_divisor: p.gas_limit_bound_divisor.into(),
+			step_duration: Duration::from_secs(p.step_duration.into()),
+			authority_n: p.authorities.len(),
+			authorities: p.authorities.into_iter().map(Into::into).collect::<Vec<_>>(),
+		}
+	}
+}
+
+/// Engine using `AuthorityRound` proof-of-work consensus algorithm, suitable for Ethereum
+/// mainnet chains in the Olympic, Frontier and Homestead eras.
+pub struct AuthorityRound {
+	params: CommonParams,
+	our_params: AuthorityRoundParams,
+	builtins: BTreeMap<Address, Builtin>,
+	transition_service: IoService<BlockArrived>,
+	message_channel: Mutex<Option<IoChannel<ClientIoMessage>>>,
+	step: AtomicUsize,
+	proposed: AtomicBool,
+}
+
+fn header_step(header: &Header) -> Result<usize, ::rlp::DecoderError> {
+	UntrustedRlp::new(&header.seal()[0]).as_val()
+}
+
+fn header_signature(header: &Header) -> Result<Signature, ::rlp::DecoderError> {
+	UntrustedRlp::new(&header.seal()[1]).as_val::<H520>().map(Into::into)
+}
+
+trait AsMillis {
+	fn as_millis(&self) -> u64;
+}
+
+impl AsMillis for Duration {
+	fn as_millis(&self) -> u64 {
+		self.as_secs()*1_000 + (self.subsec_nanos()/1_000_000) as u64
+	}
+}
+
+impl AuthorityRound {
+	/// Create a new instance of AuthorityRound engine.
+	pub fn new(params: CommonParams, our_params: AuthorityRoundParams, builtins: BTreeMap<Address, Builtin>) -> Result<Arc<Self>, Error> {
+		let initial_step = (unix_now().as_secs() / our_params.step_duration.as_secs()) as usize;
+		let engine = Arc::new(
+			AuthorityRound {
+				params: params,
+				our_params: our_params,
+				builtins: builtins,
+				transition_service: try!(IoService::<BlockArrived>::start()),
+				message_channel: Mutex::new(None),
+				step: AtomicUsize::new(initial_step),
+				proposed: AtomicBool::new(false)
+			});
+		let handler = TransitionHandler { engine: Arc::downgrade(&engine) };
+		try!(engine.transition_service.register_handler(Arc::new(handler)));
+		Ok(engine)
+	}
+
+	fn step(&self) -> usize {
+		self.step.load(AtomicOrdering::SeqCst)
+	}
+
+	fn remaining_step_duration(&self) -> Duration {
+		let now = unix_now();
+		let step_end = self.our_params.step_duration * (self.step() as u32 + 1);
+		if step_end > now {
+			step_end - now
+		} else {
+			Duration::from_secs(0)
+		}
+	}
+
+	fn step_proposer(&self, step: usize) -> &Address {
+		let ref p = self.our_params;
+		p.authorities.get(step % p.authority_n).expect("There are authority_n authorities; taking number modulo authority_n gives number in authority_n range; qed")
+	}
+
+	fn is_step_proposer(&self, step: usize, address: &Address) -> bool {
+		self.step_proposer(step) == address
+	}
+}
+
+fn unix_now() -> Duration {
+	UNIX_EPOCH.elapsed().expect("Valid time has to be set in your system.")
+}
+
+struct TransitionHandler {
+	engine: Weak<AuthorityRound>,
+}
+
+#[derive(Clone)]
+struct BlockArrived;
+
+const ENGINE_TIMEOUT_TOKEN: TimerToken = 23;
+
+impl IoHandler<BlockArrived> for TransitionHandler {
+	fn initialize(&self, io: &IoContext<BlockArrived>) {
+		if let Some(engine) = self.engine.upgrade() {
+			io.register_timer_once(ENGINE_TIMEOUT_TOKEN, engine.remaining_step_duration().as_millis())
+				.unwrap_or_else(|e| warn!(target: "poa", "Failed to start consensus step timer: {}.", e))
+		}
+	}
+
+	fn timeout(&self, io: &IoContext<BlockArrived>, timer: TimerToken) {
+		if timer == ENGINE_TIMEOUT_TOKEN {
+			if let Some(engine) = self.engine.upgrade() {
+				engine.step.fetch_add(1, AtomicOrdering::SeqCst);
+				engine.proposed.store(false, AtomicOrdering::SeqCst);
+				if let Some(ref channel) = *engine.message_channel.lock() {
+					match channel.send(ClientIoMessage::UpdateSealing) {
+						Ok(_) => trace!(target: "poa", "timeout: UpdateSealing message sent for step {}.", engine.step.load(AtomicOrdering::Relaxed)),
+						Err(err) => trace!(target: "poa", "timeout: Could not send a sealing message {} for step {}.", err, engine.step.load(AtomicOrdering::Relaxed)),
+					}
+				}
+				io.register_timer_once(ENGINE_TIMEOUT_TOKEN, engine.remaining_step_duration().as_millis())
+					.unwrap_or_else(|e| warn!(target: "poa", "Failed to restart consensus step timer: {}.", e))
+			}
+		}
+	}
+}
+
+impl Engine for AuthorityRound {
+	fn name(&self) -> &str { "AuthorityRound" }
+	fn version(&self) -> SemanticVersion { SemanticVersion::new(1, 0, 0) }
+	/// Two fields - consensus step and the corresponding proposer signature.
+	fn seal_fields(&self) -> usize { 2 }
+
+	fn params(&self) -> &CommonParams { &self.params }
+	fn builtins(&self) -> &BTreeMap<Address, Builtin> { &self.builtins }
+
+	/// Additional engine-specific information for the user/developer concerning `header`.
+	fn extra_info(&self, header: &Header) -> BTreeMap<String, String> {
+		map![
+			"step".into() => header_step(header).as_ref().map(ToString::to_string).unwrap_or("".into()),
+			"signature".into() => header_signature(header).as_ref().map(ToString::to_string).unwrap_or("".into())
+		]
+	}
+
+	fn schedule(&self, _env_info: &EnvInfo) -> Schedule {
+		Schedule::new_post_eip150(usize::max_value(), true, true, true)
+	}
+
+	fn populate_from_parent(&self, header: &mut Header, parent: &Header, gas_floor_target: U256, _gas_ceil_target: U256) {
+		header.set_difficulty(parent.difficulty().clone());
+		header.set_gas_limit({
+			let gas_limit = parent.gas_limit().clone();
+			let bound_divisor = self.our_params.gas_limit_bound_divisor;
+			if gas_limit < gas_floor_target {
+				min(gas_floor_target, gas_limit + gas_limit / bound_divisor - 1.into())
+			} else {
+				max(gas_floor_target, gas_limit - gas_limit / bound_divisor + 1.into())
+			}
+		});
+	}
+
+	/// Apply the block reward on finalisation of the block.
+	/// This assumes that all uncles are valid uncles (i.e. of at least one generation before the current).
+	fn on_close_block(&self, _block: &mut ExecutedBlock) {}
+
+	fn is_sealer(&self, author: &Address) -> Option<bool> {
+		let ref p = self.our_params;
+		Some(p.authorities.contains(author))
+	}
+
+	/// Attempt to seal the block internally.
+	///
+	/// This operation is synchronous and may (quite reasonably) not be available, in which `false` will
+	/// be returned.
+	fn generate_seal(&self, block: &ExecutedBlock, accounts: Option<&AccountProvider>) -> Option<Vec<Bytes>> {
+		if self.proposed.load(AtomicOrdering::SeqCst) { return None; }
+		let header = block.header();
+		let step = self.step();
+		if self.is_step_proposer(step, header.author()) {
+			if let Some(ap) = accounts {
+				// Account should be permanently unlocked, otherwise sealing will fail.
+				if let Ok(signature) = ap.sign(*header.author(), None, header.bare_hash()) {
+					trace!(target: "poa", "generate_seal: Issuing a block for step {}.", step);
+					self.proposed.store(true, AtomicOrdering::SeqCst);
+					return Some(vec![encode(&step).to_vec(), encode(&(&*signature as &[u8])).to_vec()]);
+				} else {
+					warn!(target: "poa", "generate_seal: FAIL: Accounts secret key unavailable.");
+				}
+			} else {
+				warn!(target: "poa", "generate_seal: FAIL: Accounts not provided.");
+			}
+		}
+		None
+	}
+
+	/// Check the number of seal fields.
+	fn verify_block_basic(&self, header: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+		if header.seal().len() != self.seal_fields() {
+			trace!(target: "poa", "verify_block_basic: wrong number of seal fields");
+			Err(From::from(BlockError::InvalidSealArity(
+				Mismatch { expected: self.seal_fields(), found: header.seal().len() }
+			)))
+		} else {
+			Ok(())
+		}
+	}
+
+	/// Check if the signature belongs to the correct proposer.
+	fn verify_block_unordered(&self, header: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+        let header_step = try!(header_step(header));
+        // Give one step slack if step is lagging, double vote is still not possible.
+		if header_step <= self.step() + 1 {
+			let proposer_signature = try!(header_signature(header));
+			let ok_sig = try!(verify_address(self.step_proposer(header_step), &proposer_signature, &header.bare_hash()));
+			if ok_sig {
+				Ok(())
+			} else {
+				trace!(target: "poa", "verify_block_unordered: invalid seal signature");
+				try!(Err(BlockError::InvalidSeal))
+			}
+		} else {
+			trace!(target: "poa", "verify_block_unordered: block from the future");
+			try!(Err(BlockError::InvalidSeal))
+		}
+	}
+
+	fn verify_block_family(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+		// Don't calculate difficulty for genesis blocks.
+		if header.number() == 0 {
+			return Err(From::from(BlockError::RidiculousNumber(OutOfBounds { min: Some(1), max: None, found: header.number() })));
+		}
+
+		let step = try!(header_step(header));
+		// Check if parent is from a previous step.
+		if step == try!(header_step(parent)) { 
+			trace!(target: "poa", "Multiple blocks proposed for step {}.", step);
+			try!(Err(BlockError::DoubleVote(header.author().clone())));
+		}
+
+		// Check difficulty is correct given the two timestamps.
+		if header.difficulty() != parent.difficulty() {
+			return Err(From::from(BlockError::InvalidDifficulty(Mismatch { expected: *parent.difficulty(), found: *header.difficulty() })))
+		}
+		let gas_limit_divisor = self.our_params.gas_limit_bound_divisor;
+		let min_gas = parent.gas_limit().clone() - parent.gas_limit().clone() / gas_limit_divisor;
+		let max_gas = parent.gas_limit().clone() + parent.gas_limit().clone() / gas_limit_divisor;
+		if header.gas_limit() <= &min_gas || header.gas_limit() >= &max_gas {
+			return Err(From::from(BlockError::InvalidGasLimit(OutOfBounds { min: Some(min_gas), max: Some(max_gas), found: header.gas_limit().clone() })));
+		}
+		Ok(())
+	}
+
+	fn verify_transaction_basic(&self, t: &SignedTransaction, _header: &Header) -> Result<(), Error> {
+		try!(t.check_low_s());
+		Ok(())
+	}
+
+	fn verify_transaction(&self, t: &SignedTransaction, _header: &Header) -> Result<(), Error> {
+		t.sender().map(|_|()) // Perform EC recovery and cache sender
+	}
+
+	fn register_message_channel(&self, message_channel: IoChannel<ClientIoMessage>) {
+		let mut guard = self.message_channel.lock();
+		*guard = Some(message_channel);
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use util::*;
+	use env_info::EnvInfo;
+	use header::Header;
+	use error::{Error, BlockError};
+	use rlp::encode;
+	use block::*;
+	use tests::helpers::*;
+	use account_provider::AccountProvider;
+	use spec::Spec;
+	use std::time::UNIX_EPOCH;
+
+	#[test]
+	fn has_valid_metadata() {
+		let engine = Spec::new_test_round().engine;
+		assert!(!engine.name().is_empty());
+		assert!(engine.version().major >= 1);
+	}
+
+	#[test]
+	fn can_return_schedule() {
+		let engine = Spec::new_test_round().engine;
+		let schedule = engine.schedule(&EnvInfo {
+			number: 10000000,
+			author: 0.into(),
+			timestamp: 0,
+			difficulty: 0.into(),
+			last_hashes: Arc::new(vec![]),
+			gas_used: 0.into(),
+			gas_limit: 0.into(),
+		});
+
+		assert!(schedule.stack_limit > 0);
+	}
+
+	#[test]
+	fn verification_fails_on_short_seal() {
+		let engine = Spec::new_test_round().engine;
+		let header: Header = Header::default();
+
+		let verify_result = engine.verify_block_basic(&header, None);
+
+		match verify_result {
+			Err(Error::Block(BlockError::InvalidSealArity(_))) => {},
+			Err(_) => { panic!("should be block seal-arity mismatch error (got {:?})", verify_result); },
+			_ => { panic!("Should be error, got Ok"); },
+		}
+	}
+
+	#[test]
+	fn can_do_signature_verification_fail() {
+		let engine = Spec::new_test_round().engine;
+		let mut header: Header = Header::default();
+		header.set_seal(vec![encode(&H520::default()).to_vec()]);
+
+		let verify_result = engine.verify_block_unordered(&header, None);
+		assert!(verify_result.is_err());
+	}
+
+	#[test]
+	fn generates_seal_and_does_not_double_propose() {
+		let tap = AccountProvider::transient_provider();
+		let addr1 = tap.insert_account("1".sha3(), "1").unwrap();
+		tap.unlock_account_permanently(addr1, "1".into()).unwrap();
+		let addr2 = tap.insert_account("2".sha3(), "2").unwrap();
+		tap.unlock_account_permanently(addr2, "2".into()).unwrap();
+
+		let spec = Spec::new_test_round();
+		let engine = &*spec.engine;
+		let genesis_header = spec.genesis_header();
+		let mut db1 = get_temp_state_db().take();
+		spec.ensure_db_good(&mut db1).unwrap();
+		let mut db2 = get_temp_state_db().take();
+		spec.ensure_db_good(&mut db2).unwrap();
+		let last_hashes = Arc::new(vec![genesis_header.hash()]);
+		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![]).unwrap();
+		let b1 = b1.close_and_lock();
+		let b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes, addr2, (3141562.into(), 31415620.into()), vec![]).unwrap();
+		let b2 = b2.close_and_lock();
+
+		if let Some(seal) = engine.generate_seal(b1.block(), Some(&tap)) {
+			assert!(b1.clone().try_seal(engine, seal).is_ok());
+			// Second proposal is forbidden.
+			assert!(engine.generate_seal(b1.block(), Some(&tap)).is_none());
+		}
+
+		if let Some(seal) = engine.generate_seal(b2.block(), Some(&tap)) {
+			assert!(b2.clone().try_seal(engine, seal).is_ok());
+			// Second proposal is forbidden.
+			assert!(engine.generate_seal(b2.block(), Some(&tap)).is_none());
+		}
+	}
+
+	#[test]
+	fn proposer_switching() {
+		let mut header: Header = Header::default();
+		let tap = AccountProvider::transient_provider();
+		let addr = tap.insert_account("0".sha3(), "0").unwrap();
+
+		header.set_author(addr);
+
+		let engine = Spec::new_test_round().engine;
+
+		let signature = tap.sign(addr, Some("0".into()), header.bare_hash()).unwrap();
+		let mut step = UNIX_EPOCH.elapsed().unwrap().as_secs();
+		header.set_seal(vec![encode(&step).to_vec(), encode(&(&*signature as &[u8])).to_vec()]);
+		let first_ok = engine.verify_block_seal(&header).is_ok();
+		step = step + 1;
+		header.set_seal(vec![encode(&step).to_vec(), encode(&(&*signature as &[u8])).to_vec()]);
+		let second_ok = engine.verify_block_seal(&header).is_ok();
+
+		assert!(first_ok ^ second_ok);
+	}
+}
--- a/ethcore/src/engines/basic_authority.rs
+++ b/ethcore/src/engines/basic_authority.rs
@ -181,13 +181,6 @@ impl Engine for BasicAuthority {
 	}
 }

-impl Header {
-	/// Get the none field of the header.
-	pub fn signature(&self) -> H520 {
-		::rlp::decode(&self.seal()[0])
-	}
-}
-
 #[cfg(test)]
 mod tests {
 	use util::*;
@ -201,7 +194,7 @@ mod tests {

 	/// Create a new test chain spec with `BasicAuthority` consensus engine.
 	fn new_test_authority() -> Spec {
-		let bytes: &[u8] = include_bytes!("../../res/test_authority.json");
+		let bytes: &[u8] = include_bytes!("../../res/basic_authority.json");
 		Spec::load(bytes).expect("invalid chain spec")
 	}

--- a/ethcore/src/engines/instant_seal.rs
+++ b/ethcore/src/engines/instant_seal.rs
@ -55,7 +55,7 @@ impl Engine for InstantSeal {
 	}

 	fn schedule(&self, _env_info: &EnvInfo) -> Schedule {
-		Schedule::new_post_eip150(false, false, false)
+		Schedule::new_post_eip150(usize::max_value(), false, false, false)
 	}

 	fn is_sealer(&self, _author: &Address) -> Option<bool> { Some(true) }
--- a/ethcore/src/engines/mod.rs
+++ b/ethcore/src/engines/mod.rs
@ -19,10 +19,12 @@
 mod null_engine;
 mod instant_seal;
 mod basic_authority;
+mod authority_round;

 pub use self::null_engine::NullEngine;
 pub use self::instant_seal::InstantSeal;
 pub use self::basic_authority::BasicAuthority;
+pub use self::authority_round::AuthorityRound;

 use util::*;
 use account_provider::AccountProvider;
@ -32,6 +34,8 @@ use env_info::EnvInfo;
 use error::Error;
 use spec::CommonParams;
 use evm::Schedule;
+use io::IoChannel;
+use service::ClientIoMessage;
 use header::Header;
 use transaction::SignedTransaction;

@ -140,5 +144,7 @@ pub trait Engine : Sync + Send {
 		self.builtins().get(a).expect("attempted to execute nonexistent builtin").execute(input, output);
 	}

+	/// Add a channel for communication with Client which can be used for sealing.
+	fn register_message_channel(&self, _message_channel: IoChannel<ClientIoMessage>) {}
 	// TODO: sealing stuff - though might want to leave this for later.
 }
--- a/ethcore/src/error.rs
+++ b/ethcore/src/error.rs
@ -167,6 +167,8 @@ pub enum BlockError {
 	UnknownParent(H256),
 	/// Uncle parent given is unknown.
 	UnknownUncleParent(H256),
+	/// The same author issued different votes at the same step.
+	DoubleVote(H160),
 }

 impl fmt::Display for BlockError {
@ -200,6 +202,7 @@ impl fmt::Display for BlockError {
 			RidiculousNumber(ref oob) => format!("Implausible block number. {}", oob),
 			UnknownParent(ref hash) => format!("Unknown parent: {}", hash),
 			UnknownUncleParent(ref hash) => format!("Unknown uncle parent: {}", hash),
+			DoubleVote(ref address) => format!("Author {} issued too many blocks.", address),
 		};

 		f.write_fmt(format_args!("Block error ({})", msg))
--- a/ethcore/src/ethereum/ethash.rs
+++ b/ethcore/src/ethereum/ethash.rs
@ -73,7 +73,9 @@ pub struct EthashParams {
 	/// Number of first block where ECIP-1010 begins.
 	pub ecip1010_pause_transition: u64,
 	/// Number of first block where ECIP-1010 ends.
-	pub ecip1010_continue_transition: u64
+	pub ecip1010_continue_transition: u64,
+	/// Maximum amount of code that can be deploying into a contract.
+	pub max_code_size: u64,
 }

 impl From<ethjson::spec::EthashParams> for EthashParams {
@ -87,19 +89,20 @@ impl From<ethjson::spec::EthashParams> for EthashParams {
 			block_reward: p.block_reward.into(),
 			registrar: p.registrar.map_or_else(Address::new, Into::into),
 			homestead_transition: p.homestead_transition.map_or(0, Into::into),
-			dao_hardfork_transition: p.dao_hardfork_transition.map_or(0x7fffffffffffffff, Into::into),
+			dao_hardfork_transition: p.dao_hardfork_transition.map_or(u64::max_value(), Into::into),
 			dao_hardfork_beneficiary: p.dao_hardfork_beneficiary.map_or_else(Address::new, Into::into),
 			dao_hardfork_accounts: p.dao_hardfork_accounts.unwrap_or_else(Vec::new).into_iter().map(Into::into).collect(),
-			difficulty_hardfork_transition: p.difficulty_hardfork_transition.map_or(0x7fffffffffffffff, Into::into),
+			difficulty_hardfork_transition: p.difficulty_hardfork_transition.map_or(u64::max_value(), Into::into),
 			difficulty_hardfork_bound_divisor: p.difficulty_hardfork_bound_divisor.map_or(p.difficulty_bound_divisor.into(), Into::into),
-			bomb_defuse_transition: p.bomb_defuse_transition.map_or(0x7fffffffffffffff, Into::into),
+			bomb_defuse_transition: p.bomb_defuse_transition.map_or(u64::max_value(), Into::into),
 			eip150_transition: p.eip150_transition.map_or(0, Into::into),
 			eip155_transition: p.eip155_transition.map_or(0, Into::into),
 			eip160_transition: p.eip160_transition.map_or(0, Into::into),
 			eip161abc_transition: p.eip161abc_transition.map_or(0, Into::into),
-			eip161d_transition: p.eip161d_transition.map_or(0x7fffffffffffffff, Into::into),
-			ecip1010_pause_transition: p.ecip1010_pause_transition.map_or(0x7fffffffffffffff, Into::into),
-			ecip1010_continue_transition: p.ecip1010_continue_transition.map_or(0x7fffffffffffffff, Into::into),
+			eip161d_transition: p.eip161d_transition.map_or(u64::max_value(), Into::into),
+			ecip1010_pause_transition: p.ecip1010_pause_transition.map_or(u64::max_value(), Into::into),
+			ecip1010_continue_transition: p.ecip1010_continue_transition.map_or(u64::max_value(), Into::into),
+			max_code_size: p.max_code_size.map_or(u64::max_value(), Into::into),
 		}
 	}
 }
@ -152,6 +155,7 @@ impl Engine for Ethash {
 			Schedule::new_homestead()
 		} else {
 			Schedule::new_post_eip150(
+				self.ethash_params.max_code_size as usize,
 				env_info.number >= self.ethash_params.eip160_transition,
 				env_info.number >= self.ethash_params.eip161abc_transition,
 				env_info.number >= self.ethash_params.eip161d_transition
--- a/ethcore/src/evm/schedule.rs
+++ b/ethcore/src/evm/schedule.rs
@ -70,6 +70,8 @@ pub struct Schedule {
 	pub quad_coeff_div: usize,
 	/// Cost for contract length when executing `CREATE`
 	pub create_data_gas: usize,
+	/// Maximum code size when creating a contract.
+	pub create_data_limit: usize,
 	/// Transaction cost
 	pub tx_gas: usize,
 	/// `CREATE` transaction cost
@ -111,7 +113,7 @@ impl Schedule {
 	}

 	/// Schedule for the post-EIP-150-era of the Ethereum main net.
-	pub fn new_post_eip150(fix_exp: bool, no_empty: bool, kill_empty: bool) -> Schedule {
+	pub fn new_post_eip150(max_code_size: usize, fix_exp: bool, no_empty: bool, kill_empty: bool) -> Schedule {
 		Schedule {
 			exceptional_failed_code_deposit: true,
 			have_delegate_call: true,
@ -139,6 +141,7 @@ impl Schedule {
 			memory_gas: 3,
 			quad_coeff_div: 512,
 			create_data_gas: 200,
+			create_data_limit: max_code_size,
 			tx_gas: 21000,
 			tx_create_gas: 53000,
 			tx_data_zero_gas: 4,
@ -183,6 +186,7 @@ impl Schedule {
 			memory_gas: 3,
 			quad_coeff_div: 512,
 			create_data_gas: 200,
+			create_data_limit: usize::max_value(),
 			tx_gas: 21000,
 			tx_create_gas: tcg,
 			tx_data_zero_gas: 4,
--- a/ethcore/src/externalities.rs
+++ b/ethcore/src/externalities.rs
@ -242,7 +242,7 @@ impl<'a, T, V> Ext for Externalities<'a, T, V> where T: 'a + Tracer, V: 'a + VMT
 			},
 			OutputPolicy::InitContract(ref mut copy) => {
 				let return_cost = U256::from(data.len()) * U256::from(self.schedule.create_data_gas);
-				if return_cost > *gas {
+				if return_cost > *gas || data.len() > self.schedule.create_data_limit {
 					return match self.schedule.exceptional_failed_code_deposit {
 						true => Err(evm::Error::OutOfGas),
 						false => Ok(*gas)
--- a/ethcore/src/miner/miner.rs
+++ b/ethcore/src/miner/miner.rs
@ -212,7 +212,8 @@ pub struct Miner {
 	sealing_block_last_request: Mutex<u64>,
 	// for sealing...
 	options: MinerOptions,
-	seals_internally: bool,
+	/// Does the node perform internal (without work) sealing.
+	pub seals_internally: bool,

 	gas_range_target: RwLock<(U256, U256)>,
 	author: RwLock<Address>,
@ -267,6 +268,11 @@ impl Miner {
 		}
 	}

+	/// Creates new instance of miner with accounts and with given spec.
+	pub fn with_spec_and_accounts(spec: &Spec, accounts: Option<Arc<AccountProvider>>) -> Miner {
+		Miner::new_raw(Default::default(), GasPricer::new_fixed(20_000_000_000u64.into()), spec, accounts)
+	}
+
 	/// Creates new instance of miner without accounts, but with given spec.
 	pub fn with_spec(spec: &Spec) -> Miner {
 		Miner::new_raw(Default::default(), GasPricer::new_fixed(20_000_000_000u64.into()), spec, None)
@ -429,6 +435,7 @@ impl Miner {
 			let last_request = *self.sealing_block_last_request.lock();
 			let should_disable_sealing = !self.forced_sealing()
 				&& !has_local_transactions
+				&& !self.seals_internally
 				&& best_block > last_request
 				&& best_block - last_request > SEALING_TIMEOUT_IN_BLOCKS;

@ -472,9 +479,10 @@ impl Miner {

 	/// Uses Engine to seal the block internally and then imports it to chain.
 	fn seal_and_import_block_internally(&self, chain: &MiningBlockChainClient, block: ClosedBlock) -> bool {
-		if !block.transactions().is_empty() {
+		if !block.transactions().is_empty() || self.forced_sealing() {
 			if let Ok(sealed) = self.seal_block_internally(block) {
 				if chain.import_block(sealed.rlp_bytes()).is_ok() {
+					trace!(target: "miner", "import_block_internally: imported internally sealed block");
 					return true
 				}
 			}
@ -773,7 +781,7 @@ impl MinerService for Miner {
 		chain: &MiningBlockChainClient,
 		transactions: Vec<SignedTransaction>
 	) -> Vec<Result<TransactionImportResult, Error>> {
-
+		trace!(target: "external_tx", "Importing external transactions");
 		let results = {
 			let mut transaction_queue = self.transaction_queue.lock();
 			self.add_transactions_to_queue(
--- a/ethcore/src/service.rs
+++ b/ethcore/src/service.rs
@ -48,6 +48,8 @@ pub enum ClientIoMessage {
 	FeedBlockChunk(H256, Bytes),
 	/// Take a snapshot for the block with given number.
 	TakeSnapshot(u64),
+	/// Trigger sealing update (useful for internal sealing).
+	UpdateSealing,
 }

 /// Client service setup. Creates and registers client and network services with the IO subsystem.
@ -111,6 +113,8 @@ impl ClientService {
 		});
 		try!(io_service.register_handler(client_io));

+		spec.engine.register_message_channel(io_service.channel());
+
 		let stop_guard = ::devtools::StopGuard::new();
 		run_ipc(ipc_path, client.clone(), snapshot.clone(), stop_guard.share());

@ -213,8 +217,11 @@ impl IoHandler<ClientIoMessage> for ClientIoHandler {
 				if let Err(e) = res {
 					debug!(target: "snapshot", "Failed to initialize periodic snapshot thread: {:?}", e);
 				}
-
-			}
+			},
+			ClientIoMessage::UpdateSealing => {
+				trace!(target: "authorityround", "message: UpdateSealing");
+				self.client.update_sealing()
+			},
 			_ => {} // ignore other messages
 		}
 	}
--- a/ethcore/src/spec/spec.rs
+++ b/ethcore/src/spec/spec.rs
@ -18,7 +18,7 @@

 use util::*;
 use builtin::Builtin;
-use engines::{Engine, NullEngine, InstantSeal, BasicAuthority};
+use engines::{Engine, NullEngine, InstantSeal, BasicAuthority, AuthorityRound};
 use pod_state::*;
 use account_db::*;
 use header::{BlockNumber, Header};
@ -150,6 +150,7 @@ impl Spec {
 			ethjson::spec::Engine::InstantSeal => Arc::new(InstantSeal::new(params, builtins)),
 			ethjson::spec::Engine::Ethash(ethash) => Arc::new(ethereum::Ethash::new(params, From::from(ethash.params), builtins)),
 			ethjson::spec::Engine::BasicAuthority(basic_authority) => Arc::new(BasicAuthority::new(params, From::from(basic_authority.params), builtins)),
+			ethjson::spec::Engine::AuthorityRound(authority_round) => AuthorityRound::new(params, From::from(authority_round.params), builtins).expect("Consensus engine could not be started."),
 		}
 	}

@ -280,6 +281,10 @@ impl Spec {

 	/// Create a new Spec with InstantSeal consensus which does internal sealing (not requiring work).
 	pub fn new_instant() -> Spec { load_bundled!("instant_seal") }
+
+	/// Create a new Spec with AuthorityRound consensus which does internal sealing (not requiring work).
+	/// Accounts with secrets "1".sha3() and "2".sha3() are the authorities.
+	pub fn new_test_round() -> Self { load_bundled!("authority_round") }
 }

 #[cfg(test)]
--- a/ethcore/src/tests/helpers.rs
+++ b/ethcore/src/tests/helpers.rs
@ -433,18 +433,19 @@ pub fn get_default_ethash_params() -> EthashParams{
 		block_reward: U256::from(0),
 		registrar: "0000000000000000000000000000000000000001".into(),
 		homestead_transition: 1150000,
-		dao_hardfork_transition: 0x7fffffffffffffff,
+		dao_hardfork_transition: u64::max_value(),
 		dao_hardfork_beneficiary: "0000000000000000000000000000000000000001".into(),
 		dao_hardfork_accounts: vec![],
-		difficulty_hardfork_transition: 0x7fffffffffffffff,
+		difficulty_hardfork_transition: u64::max_value(),
 		difficulty_hardfork_bound_divisor: U256::from(0),
-		bomb_defuse_transition: 0x7fffffffffffffff,
-		eip150_transition: 0x7fffffffffffffff,
-		eip155_transition: 0x7fffffffffffffff,
-		eip160_transition: 0x7fffffffffffffff,
-		eip161abc_transition: 0x7fffffffffffffff,
-		eip161d_transition: 0x7fffffffffffffff,
-		ecip1010_pause_transition: 0x7fffffffffffffff,
-		ecip1010_continue_transition: 0x7fffffffffffffff
+		bomb_defuse_transition: u64::max_value(),
+		eip150_transition: u64::max_value(),
+		eip155_transition: u64::max_value(),
+		eip160_transition: u64::max_value(),
+		eip161abc_transition: u64::max_value(),
+		eip161d_transition: u64::max_value(),
+		ecip1010_pause_transition: u64::max_value(),
+		ecip1010_continue_transition: u64::max_value(),
+		max_code_size: u64::max_value(),
 	}
 }
--- a/ethstore/res/wordlist.txt
+++ b/ethstore/res/wordlist.txt
--- a/js/package.json
+++ b/js/package.json
@ -1,6 +1,6 @@
 {
  "name": "parity.js",
-  "version": "0.2.46",
+  "version": "0.2.48",
  "main": "release/index.js",
  "jsnext:main": "src/index.js",
  "author": "Parity Team <admin@parity.io>",
--- a/js/src/api/contract/contract.js
+++ b/js/src/api/contract/contract.js
@ -40,9 +40,12 @@ export default class Contract {

    this._events.forEach((evt) => {
      this._instance[evt.name] = evt;
+      this._instance[evt.signature] = evt;
    });
+
    this._functions.forEach((fn) => {
      this._instance[fn.name] = fn;
+      this._instance[fn.signature] = fn;
    });

    this._sendSubscriptionChanges();
--- a/js/src/api/contract/contract.spec.js
+++ b/js/src/api/contract/contract.spec.js
@ -20,6 +20,7 @@ import sinon from 'sinon';
 import { TEST_HTTP_URL, mockHttp } from '../../../test/mockRpc';

 import Abi from '../../abi';
+import { sha3 } from '../util/sha3';

 import Api from '../api';
 import Contract from './contract';
@ -113,7 +114,13 @@ describe('api/contract/Contract', () => {
      ]);
      contract.at('6789');

-      expect(Object.keys(contract.instance)).to.deep.equal(['Drained', 'balanceOf', 'address']);
+      expect(Object.keys(contract.instance)).to.deep.equal([
+        'Drained',
+        /^(?:0x)(.+)$/.exec(sha3('Drained(uint256)'))[1],
+        'balanceOf',
+        /^(?:0x)(.+)$/.exec(sha3('balanceOf(address)'))[1].substr(0, 8),
+        'address'
+      ]);
      expect(contract.address).to.equal('6789');
    });
  });
--- a/js/src/dapps/basiccoin/Deploy/Event/event.css
+++ b/js/src/dapps/basiccoin/Deploy/Event/event.css
@ -46,11 +46,22 @@ a.link, a.link:hover, a.link:visited {
 }

 .address {
+  max-width: 250px;
  text-align: left;
+
+  div {
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+  }
 }

 .description {
  text-align: left;
+
+  div {
+    white-space: nowrap;
+  }
 }

 .center {
--- a/js/src/dapps/basiccoin/Deploy/Event/event.js
+++ b/js/src/dapps/basiccoin/Deploy/Event/event.js
@ -58,6 +58,7 @@ export default class Event extends Component {
        <td className={ styles.description }>
          <div>{ isPending ? '' : coin.tla }</div>
          <div>{ isPending ? '' : coin.name }</div>
+          <div>{ this.renderAddress(event.params.coin) }</div>
        </td>
        <td className={ styles.address }>
          { this.renderAddress(event.params.owner) }
--- a/js/src/dapps/basiccoin/Overview/Owner/owner.css
+++ b/js/src/dapps/basiccoin/Overview/Owner/owner.css
@ -46,3 +46,9 @@
 .icon {
  margin: 0 0 -4px 1em;
 }
+
+.byline {
+  opacity: 0.75;
+  font-size: 0.75em;
+  padding-top: 0.25em;
+}
--- a/js/src/dapps/basiccoin/Overview/Owner/owner.js
+++ b/js/src/dapps/basiccoin/Overview/Owner/owner.js
@ -68,6 +68,9 @@ export default class Owner extends Component {
        <Token
          address={ token.address }
          tokenreg={ token.tokenreg } />
+        <div className={ styles.byline }>
+          { token.address }
+        </div>
      </div>
    ));
  }
--- a/js/src/modals/AddContract/addContract.js
+++ b/js/src/modals/AddContract/addContract.js
@ -227,6 +227,7 @@ export default class AddContract extends Component {
  onEditAbi = (abiIn) => {
    const { api } = this.context;
    const { abi, abiError, abiParsed } = validateAbi(abiIn, api);
+
    this.setState({ abi, abiError, abiParsed });
  }

--- a/js/src/modals/Transfer/transfer.js
+++ b/js/src/modals/Transfer/transfer.js
@ -314,7 +314,7 @@ export default class Transfer extends Component {
    }

    const token = balance.tokens.find((balance) => balance.token.tag === tag).token;
-    const s = new BigNumber(num).mul(token.format || 1).toString();
+    const s = new BigNumber(num).mul(token.format || 1).toFixed();

    if (s.indexOf('.') !== -1) {
      return ERRORS.invalidDecimals;
@ -516,6 +516,13 @@ export default class Transfer extends Component {
  }

  recalculateGas = () => {
+    if (!this.isValid()) {
+      this.setState({
+        gas: '0'
+      }, this.recalculate);
+      return;
+    }
+
    (this.state.isEth
      ? this._estimateGasEth()
      : this._estimateGasToken()
--- a/js/src/ui/Actionbar/Export/export.js
+++ b/js/src/ui/Actionbar/Export/export.js
@ -15,6 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

 import React, { Component, PropTypes } from 'react';
+
 import FileSaver from 'file-saver';
 import FileDownloadIcon from 'material-ui/svg-icons/file/file-download';

@ -38,19 +39,18 @@ class ActionbarExport extends Component {
        className={ className }
        icon={ <FileDownloadIcon /> }
        label='export'
-        onClick={ this.onDownloadBackup } />
+        onClick={ this.handleExport }
+      />
    );
  }

-  onDownloadBackup = () => {
+  handleExport = () => {
    const { filename, content } = this.props;

-    const text = (typeof content === 'string')
-      ? content
-      : JSON.stringify(content, null, 4);
+    const text = JSON.stringify(content, null, 4);

-    const blob = new Blob([ text ], { type: 'text/plain;charset=utf-8' });
-    FileSaver.saveAs(blob, filename);
+    const blob = new Blob([ text ], { type: 'application/json' });
+    FileSaver.saveAs(blob, `${filename}.json`);
  }
 }

--- a/js/src/ui/Actionbar/Sort/sort.js
+++ b/js/src/ui/Actionbar/Sort/sort.js
@ -15,6 +15,8 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

 import React, { Component, PropTypes } from 'react';
+import { observer } from 'mobx-react';
+
 import IconMenu from 'material-ui/IconMenu';
 import MenuItem from 'material-ui/MenuItem';

@ -22,11 +24,15 @@ import SortIcon from 'material-ui/svg-icons/content/sort';

 import { Button } from '../../';

+import SortStore from './sortStore';
 import styles from './sort.css';

+@observer
 export default class ActionbarSort extends Component {
  static propTypes = {
+    id: PropTypes.string.isRequired,
    onChange: PropTypes.func.isRequired,
+
    order: PropTypes.string,
    showDefault: PropTypes.bool,
    metas: PropTypes.array
@ -37,8 +43,10 @@ export default class ActionbarSort extends Component {
    showDefault: true
  }

-  state = {
-    menuOpen: false
+  store = new SortStore(this.props);
+
+  componentDidMount () {
+    this.store.restoreSavedOrder();
  }

  render () {
@ -51,12 +59,12 @@ export default class ActionbarSort extends Component {
            className={ styles.sortButton }
            label=''
            icon={ <SortIcon /> }
-            onClick={ this.handleMenuOpen }
+            onClick={ this.store.handleMenuOpen }
            />
        }
-        open={ this.state.menuOpen }
-        onRequestChange={ this.handleMenuChange }
-        onItemTouchTap={ this.handleSortChange }
+        open={ this.store.menuOpen }
+        onRequestChange={ this.store.handleMenuChange }
+        onItemTouchTap={ this.store.handleSortChange }
        targetOrigin={ { horizontal: 'right', vertical: 'top' } }
        anchorOrigin={ { horizontal: 'right', vertical: 'top' } }
        touchTapCloseDelay={ 0 }
@ -109,16 +117,4 @@ export default class ActionbarSort extends Component {
    );
  }

-  handleSortChange = (event, child) => {
-    const order = child.props.value;
-    this.props.onChange(order);
-  }
-
-  handleMenuOpen = () => {
-    this.setState({ menuOpen: true });
-  }
-
-  handleMenuChange = (open) => {
-    this.setState({ menuOpen: open });
-  }
 }
--- a/js/src/ui/Actionbar/Sort/sortStore.js
+++ b/js/src/ui/Actionbar/Sort/sortStore.js
@ -0,0 +1,71 @@
+// Copyright 2015, 2016 Ethcore (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+import { action, observable } from 'mobx';
+import store from 'store';
+
+const LS_STORE_KEY = '_parity::sortStore';
+
+export default class SortStore {
+  @observable menuOpen = false;
+
+  constructor (props) {
+    const { id, onChange } = props;
+
+    this.onChange = onChange;
+    this.id = id;
+  }
+
+  @action handleMenuOpen = () => {
+    this.menuOpen = true;
+  }
+
+  @action handleMenuChange = (open) => {
+    this.menuOpen = open;
+  }
+
+  @action handleSortChange = (event, child) => {
+    const order = child.props.value;
+    this.onChange(order);
+    this.saveOrder(order);
+  }
+
+  @action restoreSavedOrder = () => {
+    const order = this.getSavedOrder();
+    this.onChange(order);
+  }
+
+  getSavedOrder = () => {
+    return (this.getSavedOrders())[this.id];
+  }
+
+  getSavedOrders = () => {
+    return store.get(LS_STORE_KEY) || {};
+  }
+
+  setSavedOrders = (orders) => {
+    store.set(LS_STORE_KEY, orders);
+  }
+
+  saveOrder = (order) => {
+    const orders = {
+      ...this.getSavedOrders(),
+      [ this.id ]: order
+    };
+
+    this.setSavedOrders(orders);
+  }
+}
--- a/js/src/ui/Form/Input/input.js
+++ b/js/src/ui/Form/Input/input.js
@ -16,6 +16,7 @@

 import React, { Component, PropTypes } from 'react';
 import { TextField } from 'material-ui';
+import { noop } from 'lodash';

 import CopyToClipboard from '../../CopyToClipboard';

@ -81,7 +82,7 @@ export default class Input extends Component {
  }

  componentWillReceiveProps (newProps) {
-    if (newProps.value !== this.props.value) {
+    if ((newProps.value !== this.props.value) && (newProps.value !== this.state.value)) {
      this.setValue(newProps.value);
    }
  }
@ -131,6 +132,7 @@ export default class Input extends Component {
          onBlur={ this.onBlur }
          onChange={ this.onChange }
          onKeyDown={ this.onKeyDown }
+          onPaste={ this.onPaste }
          inputStyle={ inputStyle }
          min={ min }
          max={ max }
@ -180,9 +182,9 @@ export default class Input extends Component {
  }

  onChange = (event, value) => {
-    this.setValue(value);
-
-    this.props.onChange && this.props.onChange(event, value);
+    this.setValue(value, () => {
+      this.props.onChange && this.props.onChange(event, value);
+    });
  }

  onBlur = (event) => {
@ -196,6 +198,14 @@ export default class Input extends Component {
    this.props.onBlur && this.props.onBlur(event);
  }

+  onPaste = (event) => {
+    const value = event.clipboardData.getData('Text');
+
+    window.setTimeout(() => {
+      this.onSubmit(value);
+    }, 0);
+  }
+
  onKeyDown = (event) => {
    const { value } = event.target;

@ -209,12 +219,12 @@ export default class Input extends Component {
  }

  onSubmit = (value) => {
-    this.setValue(value);
-
-    this.props.onSubmit && this.props.onSubmit(value);
+    this.setValue(value, () => {
+      this.props.onSubmit && this.props.onSubmit(value);
+    });
  }

-  setValue (value) {
-    this.setState({ value });
+  setValue (value, cb = noop) {
+    this.setState({ value }, cb);
  }
 }
--- a/js/src/ui/Form/InputAddress/inputAddress.css
+++ b/js/src/ui/Form/InputAddress/inputAddress.css
@ -30,6 +30,10 @@
 .iconDisabled {
  position: absolute;
  top: 35px;
+
+  &.noLabel {
+    top: 10px;
+  }
 }

 .icon {
--- a/js/src/ui/Form/InputAddress/inputAddress.js
+++ b/js/src/ui/Form/InputAddress/inputAddress.js
@ -69,14 +69,19 @@ class InputAddress extends Component {
  }

  renderIcon () {
-    const { value, disabled } = this.props;
+    const { value, disabled, label } = this.props;

    if (!value || !value.length || !util.isAddressValid(value)) {
      return null;
    }

+    const classes = [disabled ? styles.iconDisabled : styles.icon];
+    if (!label) {
+      classes.push(styles.noLabel);
+    }
+
    return (
-      <div className={ disabled ? styles.iconDisabled : styles.icon }>
+      <div className={ classes.join(' ') }>
        <IdentityIcon
          inline center
          address={ value } />
--- a/js/src/util/validation.js
+++ b/js/src/util/validation.js
@ -44,7 +44,7 @@ export function validateAbi (abi, api) {

    // Validate each elements of the Array
    const invalidIndex = abiParsed
-      .map((o) => isValidAbiEvent(o, api) || isValidAbiFunction(o, api))
+      .map((o) => isValidAbiEvent(o, api) || isValidAbiFunction(o, api) || isAbiFallback(o))
      .findIndex((valid) => !valid);

    if (invalidIndex !== -1) {
@ -74,6 +74,14 @@ function isValidAbiFunction (object, api) {
    (object.inputs && api.util.isArray(object.inputs));
 }

+function isAbiFallback (object) {
+  if (!object) {
+    return false;
+  }
+
+  return object.type === 'fallback';
+}
+
 function isValidAbiEvent (object, api) {
  if (!object) {
    return false;
--- a/js/src/views/Accounts/accounts.js
+++ b/js/src/views/Accounts/accounts.js
@ -22,7 +22,7 @@ import { uniq } from 'lodash';

 import List from './List';
 import { CreateAccount } from '../../modals';
-import { Actionbar, ActionbarSearch, ActionbarSort, Button, Page, Tooltip } from '../../ui';
+import { Actionbar, ActionbarExport, ActionbarSearch, ActionbarSort, Button, Page, Tooltip } from '../../ui';

 import styles from './accounts.css';

@ -90,12 +90,15 @@ class Accounts extends Component {
    return (
      <ActionbarSort
        key='sortAccounts'
+        id='sortAccounts'
        order={ this.state.sortOrder }
        onChange={ onChange } />
    );
  }

  renderActionbar () {
+    const { accounts } = this.props;
+
    const buttons = [
      <Button
        key='newAccount'
@ -103,6 +106,11 @@ class Accounts extends Component {
        label='new account'
        onClick={ this.onNewAccountClick } />,

+      <ActionbarExport
+        key='exportAccounts'
+        content={ accounts }
+        filename='accounts' />,
+
      this.renderSearchButton(),
      this.renderSortButton()
    ];
--- a/js/src/views/Addresses/addresses.js
+++ b/js/src/views/Addresses/addresses.js
@ -75,6 +75,7 @@ class Addresses extends Component {
    return (
      <ActionbarSort
        key='sortAccounts'
+        id='sortAddresses'
        order={ this.state.sortOrder }
        onChange={ onChange } />
    );
@ -106,7 +107,7 @@ class Addresses extends Component {
      <ActionbarExport
        key='exportAddressbook'
        content={ contacts }
-        filename='addressbook.json' />,
+        filename='addressbook' />,

      <ActionbarImport
        key='importAddressbook'
--- a/js/src/views/Contract/Queries/inputQuery.js
+++ b/js/src/views/Contract/Queries/inputQuery.js
@ -19,7 +19,7 @@ import React, { Component, PropTypes } from 'react';
 import LinearProgress from 'material-ui/LinearProgress';
 import { Card, CardActions, CardTitle, CardText } from 'material-ui/Card';

-import { Button, Input, InputAddressSelect } from '../../../ui';
+import { Button, Input, InputAddress, InputAddressSelect } from '../../../ui';

 import styles from './queries.css';

@ -33,6 +33,7 @@ export default class InputQuery extends Component {
    inputs: PropTypes.array.isRequired,
    outputs: PropTypes.array.isRequired,
    name: PropTypes.string.isRequired,
+    signature: PropTypes.string.isRequired,
    className: PropTypes.string
  }

@ -95,32 +96,48 @@ export default class InputQuery extends Component {
    }

    if (!results || results.length < 1) return null;
-
    return outputs
      .map((out, index) => ({
        name: out.name,
+        type: out.type,
        value: results[index],
        display: this.renderValue(results[index])
      }))
      .sort((outA, outB) => outA.display.length - outB.display.length)
-      .map((out, index) => (
-        <div key={ index }>
-          <div className={ styles.queryResultName }>
-            { out.name }
-          </div>
+      .map((out, index) => {
+        let input = null;
+        if (out.type === 'address') {
+          input = (
+            <InputAddress
+              className={ styles.queryValue }
+              disabled
+              value={ out.display }
+            />
+          );
+        } else {
+          input = (
+            <Input
+              className={ styles.queryValue }
+              readOnly
+              allowCopy
+              value={ out.display }
+            />
+          );
+        }

-          <Input
-            className={ styles.queryValue }
-            readOnly
-            allowCopy
-            value={ out.display }
-          />
-          <br />
-        </div>
-      ));
+        return (
+          <div key={ index }>
+            <div className={ styles.queryResultName }>
+              { out.name }
+            </div>
+            { input }
+          </div>
+        );
+      });
  }

  renderInput (input) {
+    const { values } = this.state;
    const { name, type } = input;
    const label = `${name ? `${name}: ` : ''}${type}`;

@ -142,6 +159,7 @@ export default class InputQuery extends Component {
          <InputAddressSelect
            hint={ type }
            label={ label }
+            value={ values[name] }
            required
            onChange={ onChange }
          />
@ -154,6 +172,7 @@ export default class InputQuery extends Component {
        <Input
          hint={ type }
          label={ label }
+          value={ values[name] }
          required
          onChange={ onChange }
        />
@ -177,7 +196,7 @@ export default class InputQuery extends Component {

  onClick = () => {
    const { values } = this.state;
-    const { inputs, contract, name, outputs } = this.props;
+    const { inputs, contract, name, outputs, signature } = this.props;

    this.setState({
      isLoading: true,
@ -187,7 +206,7 @@ export default class InputQuery extends Component {
    const inputValues = inputs.map(input => values[input.name]);

    contract
-      .instance[name]
+      .instance[signature]
      .call({}, inputValues)
      .then(results => {
        if (outputs.length === 1) {
--- a/js/src/views/Contract/Queries/queries.css
+++ b/js/src/views/Contract/Queries/queries.css
@ -56,18 +56,10 @@
 }

 .methodResults {
-  display: flex;
-  flex-wrap: wrap;
-  max-width: 24rem;
-  justify-content: space-around;
 }

 .methodResults > div {
  padding: 0.25rem 0.5rem;
-  display: flex;
-  flex-direction: column;
-  align-items: center;
-  flex: 1 1 50%;
  box-sizing: border-box;

  & > div {
--- a/js/src/views/Contract/Queries/queries.js
+++ b/js/src/views/Contract/Queries/queries.js
@ -19,7 +19,7 @@ import React, { Component, PropTypes } from 'react';
 import { Card, CardTitle, CardText } from 'material-ui/Card';

 import InputQuery from './inputQuery';
-import { Container, ContainerTitle, Input } from '../../../ui';
+import { Container, ContainerTitle, Input, InputAddress } from '../../../ui';

 import styles from './queries.css';

@ -70,7 +70,7 @@ export default class Queries extends Component {
  }

  renderInputQuery (fn) {
-    const { abi, name } = fn;
+    const { abi, name, signature } = fn;
    const { contract } = this.props;

    return (
@ -80,6 +80,7 @@ export default class Queries extends Component {
          inputs={ abi.inputs }
          outputs={ abi.outputs }
          name={ name }
+          signature={ signature }
          contract={ contract }
        />
      </div>
@ -99,14 +100,14 @@ export default class Queries extends Component {
          <CardText
            className={ styles.methodContent }
          >
-            { this.renderValue(values[fn.name]) }
+            { this.renderValue(values[fn.name], fn.outputs[0].kind.type) }
          </CardText>
        </Card>
      </div>
    );
  }

-  renderValue (value) {
+  renderValue (value, type) {
    if (typeof value === 'undefined') {
      return null;
    }
@ -124,6 +125,16 @@ export default class Queries extends Component {
      valueToDisplay = value.toString();
    }

+    if (type === 'address') {
+      return (
+        <InputAddress
+          className={ styles.queryValue }
+          value={ valueToDisplay }
+          disabled
+        />
+      );
+    }
+
    return (
      <Input
        className={ styles.queryValue }
--- a/js/src/views/Contracts/contracts.js
+++ b/js/src/views/Contracts/contracts.js
@ -82,6 +82,7 @@ class Contracts extends Component {
    return (
      <ActionbarSort
        key='sortAccounts'
+        id='sortContracts'
        order={ this.state.sortOrder }
        metas={ [
          { key: 'timestamp', label: 'date' }
--- a/js/src/views/Signer/components/Account/Account.css
+++ b/js/src/views/Signer/components/Account/Account.css
@ -17,6 +17,9 @@
 .acc {
  text-align: center;
  display: inline-block;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  width: 100%;
 }

 .acc > * {
@ -35,10 +38,13 @@
 }

 .name {
-  text-overflow: ellipsis;
-  overflow: hidden;
  white-space: nowrap;
-  display: lock;
+  display: block;
  vertical-align: middle;
  text-transform: uppercase;
+
+  span {
+    text-overflow: ellipsis;
+    overflow: hidden;
+  }
 }
--- a/js/src/views/Signer/components/TransactionFinished/TransactionFinished.css
+++ b/js/src/views/Signer/components/TransactionFinished/TransactionFinished.css
@ -38,7 +38,9 @@
 }

 .transactionDetails {
-  margin-right: 321px;
+  padding-right: 321px;
+  width: 100%;
+  box-sizing: border-box;
 }

 .isConfirmed {
--- a/js/src/views/Signer/components/TransactionPending/TransactionPending.css
+++ b/js/src/views/Signer/components/TransactionPending/TransactionPending.css
@ -19,7 +19,9 @@
 }

 .transactionDetails {
-  margin-right: 321px;
+  padding-right: 321px;
+  width: 100%;
+  box-sizing: border-box;
 }

 .mainContainer {
--- a/js/src/views/Signer/containers/Embedded/embedded.css
+++ b/js/src/views/Signer/containers/Embedded/embedded.css
@ -15,6 +15,7 @@
 /* along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 */
 .signer {
+  width: 916px;
 }

 .pending {
--- a/js/webpack.vendor.js
+++ b/js/webpack.vendor.js
@ -14,6 +14,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

+const HappyPack = require('happypack');
 const webpack = require('webpack');

 const ENV = process.env.NODE_ENV || 'development';
@ -22,10 +23,26 @@ const DEST = process.env.BUILD_DEST || '.build';

 let modules = [
  'babel-polyfill',
-  'browserify-aes', 'ethereumjs-tx', 'scryptsy',
-  'react', 'react-dom', 'react-redux', 'react-router',
-  'redux', 'redux-thunk', 'react-router-redux',
-  'lodash', 'material-ui', 'moment', 'blockies'
+  'bignumber.js',
+  'blockies',
+  'brace',
+  'browserify-aes',
+  'chart.js',
+  'ethereumjs-tx',
+  'lodash',
+  'material-ui',
+  'mobx',
+  'mobx-react',
+  'moment',
+  'react',
+  'react-dom',
+  'react-redux',
+  'react-router',
+  'react-router-redux',
+  'recharts',
+  'redux',
+  'redux-thunk',
+  'scryptsy'
 ];

 if (!isProd) {
@ -44,6 +61,11 @@ module.exports = {
      {
        test: /\.json$/,
        loaders: ['json']
+      },
+      {
+        test: /\.js$/,
+        include: /(ethereumjs-tx)/,
+        loaders: [ 'happypack/loader?id=js' ]
      }
    ]
  },
@ -63,6 +85,12 @@ module.exports = {
        'process.env': {
          NODE_ENV: JSON.stringify(ENV)
        }
+      }),
+
+      new HappyPack({
+        id: 'js',
+        threads: 4,
+        loaders: ['babel']
      })
    ];

--- a/json/src/spec/authority_round.rs
+++ b/json/src/spec/authority_round.rs
@ -0,0 +1,59 @@
+// Copyright 2015, 2016 Ethcore (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Authority params deserialization.
+
+use uint::Uint;
+use hash::Address;
+
+/// Authority params deserialization.
+#[derive(Debug, PartialEq, Deserialize)]
+pub struct AuthorityRoundParams {
+	/// Gas limit divisor.
+	#[serde(rename="gasLimitBoundDivisor")]
+	pub gas_limit_bound_divisor: Uint,
+	/// Block duration.
+	#[serde(rename="stepDuration")]
+	pub step_duration: Uint,
+	/// Valid authorities
+	pub authorities: Vec<Address>,
+}
+
+/// Authority engine deserialization.
+#[derive(Debug, PartialEq, Deserialize)]
+pub struct AuthorityRound {
+	/// Ethash params.
+	pub params: AuthorityRoundParams,
+}
+
+#[cfg(test)]
+mod tests {
+	use serde_json;
+	use spec::authority_round::AuthorityRound;
+
+	#[test]
+	fn basic_authority_deserialization() {
+		let s = r#"{
+			"params": {
+				"gasLimitBoundDivisor": "0x0400",
+				"stepDuration": "0x02",
+				"authorities" : ["0xc6d9d2cd449a754c494264e1809c50e34d64562b"]
+			}
+		}"#;
+
+		let _deserialized: AuthorityRound = serde_json::from_str(s).unwrap();
+	}
+}
--- a/json/src/spec/engine.rs
+++ b/json/src/spec/engine.rs
@ -18,6 +18,7 @@

 use spec::Ethash;
 use spec::BasicAuthority;
+use spec::AuthorityRound;

 /// Engine deserialization.
 #[derive(Debug, PartialEq, Deserialize)]
@ -30,6 +31,8 @@ pub enum Engine {
 	Ethash(Ethash),
 	/// BasicAuthority engine.
 	BasicAuthority(BasicAuthority),
+	/// AuthorityRound engine.
+	AuthorityRound(AuthorityRound),
 }

 #[cfg(test)]
--- a/json/src/spec/ethash.rs
+++ b/json/src/spec/ethash.rs
@ -92,6 +92,11 @@ pub struct EthashParams {
 	/// See main EthashParams docs.
 	#[serde(rename="ecip1010ContinueTransition")]
 	pub ecip1010_continue_transition: Option<Uint>,
+
+	/// See main EthashParams docs.
+	#[serde(rename="maxCodeSize")]
+	pub max_code_size: Option<Uint>,
+
 }

 /// Ethash engine deserialization.
--- a/json/src/spec/mod.rs
+++ b/json/src/spec/mod.rs
@ -26,6 +26,7 @@ pub mod engine;
 pub mod state;
 pub mod ethash;
 pub mod basic_authority;
+pub mod authority_round;

 pub use self::account::Account;
 pub use self::builtin::{Builtin, Pricing, Linear};
@ -37,3 +38,4 @@ pub use self::engine::Engine;
 pub use self::state::State;
 pub use self::ethash::{Ethash, EthashParams};
 pub use self::basic_authority::{BasicAuthority, BasicAuthorityParams};
+pub use self::authority_round::{AuthorityRound, AuthorityRoundParams};
--- a/parity/blockchain.rs
+++ b/parity/blockchain.rs
@ -165,6 +165,9 @@ fn execute_import(cmd: ImportBlockchain) -> Result<String, String> {
 		Arc::new(Miner::with_spec(&spec)),
 	).map_err(|e| format!("Client service error: {:?}", e)));

+	// free up the spec in memory.
+	drop(spec);
+
 	panic_handler.forward_from(&service);
 	let client = service.client();

@ -312,6 +315,8 @@ fn execute_export(cmd: ExportBlockchain) -> Result<String, String> {
 		Arc::new(Miner::with_spec(&spec)),
 	).map_err(|e| format!("Client service error: {:?}", e)));

+	drop(spec);
+
 	panic_handler.forward_from(&service);
 	let client = service.client();

--- a/parity/run.rs
+++ b/parity/run.rs
@ -235,6 +235,9 @@ pub fn execute(cmd: RunCmd, logger: Arc<RotatingLogger>) -> Result<(), String> {
 		miner.clone(),
 	).map_err(|e| format!("Client service error: {:?}", e)));

+	// drop the spec to free up genesis state.
+	drop(spec);
+
 	// forward panics from service
 	panic_handler.forward_from(&service);

--- a/parity/snapshot.rs
+++ b/parity/snapshot.rs
@ -183,7 +183,6 @@ impl SnapshotCommand {

 		Ok((service, panic_handler))
 	}
-
 	/// restore from a snapshot
 	pub fn restore(self) -> Result<(), String> {
 		let file = self.file_path.clone();
--- a/util/io/src/service.rs
+++ b/util/io/src/service.rs
@ -56,6 +56,7 @@ pub enum IoMessage<Message> where Message: Send + Clone + Sized {
 		handler_id: HandlerId,
 		token: TimerToken,
 		delay: u64,
+		once: bool,
 	},
 	RemoveTimer {
 		handler_id: HandlerId,
@ -92,12 +93,24 @@ impl<Message> IoContext<Message> where Message: Send + Clone + Sync + 'static {
 		}
 	}

-	/// Register a new IO timer. 'IoHandler::timeout' will be called with the token.
+	/// Register a new recurring IO timer. 'IoHandler::timeout' will be called with the token.
 	pub fn register_timer(&self, token: TimerToken, ms: u64) -> Result<(), IoError> {
 		try!(self.channel.send_io(IoMessage::AddTimer {
 			token: token,
 			delay: ms,
 			handler_id: self.handler,
+			once: false,
+		}));
+		Ok(())
+	}
+
+	/// Register a new IO timer once. 'IoHandler::timeout' will be called with the token.
+	pub fn register_timer_once(&self, token: TimerToken, ms: u64) -> Result<(), IoError> {
+		try!(self.channel.send_io(IoMessage::AddTimer {
+			token: token,
+			delay: ms,
+			handler_id: self.handler,
+			once: true,
 		}));
 		Ok(())
 	}
@ -163,6 +176,7 @@ impl<Message> IoContext<Message> where Message: Send + Clone + Sync + 'static {
 struct UserTimer {
 	delay: u64,
 	timeout: Timeout,
+	once: bool,
 }

 /// Root IO handler. Manages user handlers, messages and IO timers.
@ -235,8 +249,14 @@ impl<Message> Handler for IoManager<Message> where Message: Send + Clone + Sync
 		let handler_index  = token.0  / TOKENS_PER_HANDLER;
 		let token_id  = token.0  % TOKENS_PER_HANDLER;
 		if let Some(handler) = self.handlers.read().get(handler_index) {
-			if let Some(timer) = self.timers.read().get(&token.0) {
-				event_loop.timeout(token, Duration::from_millis(timer.delay)).expect("Error re-registering user timer");
+			let maybe_timer = self.timers.read().get(&token.0).cloned();
+			if let Some(timer) = maybe_timer {
+				if timer.once {
+					self.timers.write().remove(&token_id);
+					event_loop.clear_timeout(&timer.timeout);
+				} else {
+					event_loop.timeout(token, Duration::from_millis(timer.delay)).expect("Error re-registering user timer");
+				}
 				self.worker_channel.push(Work { work_type: WorkType::Timeout, token: token_id, handler: handler.clone(), handler_id: handler_index });
 				self.work_ready.notify_all();
 			}
@ -264,10 +284,10 @@ impl<Message> Handler for IoManager<Message> where Message: Send + Clone + Sync
 					event_loop.clear_timeout(&timer.timeout);
 				}
 			},
-			IoMessage::AddTimer { handler_id, token, delay } => {
+			IoMessage::AddTimer { handler_id, token, delay, once } => {
 				let timer_id = token + handler_id * TOKENS_PER_HANDLER;
 				let timeout = event_loop.timeout(Token(timer_id), Duration::from_millis(delay)).expect("Error registering user timer");
-				self.timers.write().insert(timer_id, UserTimer { delay: delay, timeout: timeout });
+				self.timers.write().insert(timer_id, UserTimer { delay: delay, timeout: timeout, once: once });
 			},
 			IoMessage::RemoveTimer { handler_id, token } => {
 				let timer_id = token + handler_id * TOKENS_PER_HANDLER;