Don't block sync when importing old blocks (#8530)

* Alter IO queueing.

* Don't require IoMessages to be Clone

* Ancient blocks imported via IoChannel.

* Get rid of private transactions io message.

* Get rid of deadlock and fix disconnected handler.

* Revert to old disconnect condition.

* Fix tests.

* Fix deadlock.

Cargo.lock

@@ -818,6 +818,7 @@ dependencies = [
  "log 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "stop-guard 0.1.0",
  "tempdir 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "trace-time 0.1.0",
 ]
 
 [[package]]
@@ -866,6 +867,7 @@ dependencies = [
  "rustc-hex 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "trace-time 0.1.0",
  "triehash 0.1.0",
 ]
 

ethcore/private-tx/src/lib.rs

@@ -149,8 +149,8 @@ impl Provider where {
 		encryptor: Box<Encryptor>,
 		config: ProviderConfig,
 		channel: IoChannel<ClientIoMessage>,
-	) -> Result<Self, Error> {
+	) -> Self {
-		Ok(Provider {
+		Provider {
 			encryptor,
 			validator_accounts: config.validator_accounts.into_iter().collect(),
 			signer_account: config.signer_account,
@@ -162,7 +162,7 @@ impl Provider where {
 			miner,
 			accounts,
 			channel,
-		})
+		}
 	}
 
 	// TODO [ToDr] Don't use `ChainNotify` here!
@@ -243,50 +243,6 @@ impl Provider where {
 		Ok(original_transaction)
 	}
 
-	/// Process received private transaction
-	pub fn import_private_transaction(&self, rlp: &[u8]) -> Result<(), Error> {
-		trace!("Private transaction received");
-		let private_tx: PrivateTransaction = Rlp::new(rlp).as_val()?;
-		let contract = private_tx.contract;
-		let contract_validators = self.get_validators(BlockId::Latest, &contract)?;
-
-		let validation_account = contract_validators
-			.iter()
-			.find(|address| self.validator_accounts.contains(address));
-
-		match validation_account {
-			None => {
-				// TODO [ToDr] This still seems a bit invalid, imho we should still import the transaction to the pool.
-				// Importing to pool verifies correctness and nonce; here we are just blindly forwarding.
-				//
-				// Not for verification, broadcast further to peers
-				self.broadcast_private_transaction(rlp.into());
-				return Ok(());
-			},
-			Some(&validation_account) => {
-				let hash = private_tx.hash();
-				trace!("Private transaction taken for verification");
-				let original_tx = self.extract_original_transaction(private_tx, &contract)?;
-				trace!("Validating transaction: {:?}", original_tx);
-				// Verify with the first account available
-				trace!("The following account will be used for verification: {:?}", validation_account);
-				let nonce_cache = Default::default();
-				self.transactions_for_verification.lock().add_transaction(
-					original_tx,
-					contract,
-					validation_account,
-					hash,
-					self.pool_client(&nonce_cache),
-				)?;
-				// NOTE This will just fire `on_private_transaction_queued` but from a client thread.
-				// It seems that a lot of heavy work (verification) is done in this thread anyway
-				// it might actually make sense to decouple it from clientService and just use dedicated thread
-				// for both verification and execution.
-				self.channel.send(ClientIoMessage::NewPrivateTransaction).map_err(|_| ErrorKind::ClientIsMalformed.into())
-			}
-		}
-	}
-
 	fn pool_client<'a>(&'a self, nonce_cache: &'a RwLock<HashMap<Address, U256>>) -> miner::pool_client::PoolClient<'a, Client> {
 		let engine = self.client.engine();
 		let refuse_service_transactions = true;
@@ -299,11 +255,6 @@ impl Provider where {
 		)
 	}
 
-	/// Private transaction for validation added into queue
-	pub fn on_private_transaction_queued(&self) -> Result<(), Error> {
-		self.process_queue()
-	}
-
 	/// Retrieve and verify the first available private transaction for every sender
 	///
 	/// TODO [ToDr] It seems that:
@@ -347,73 +298,6 @@ impl Provider where {
 		Ok(())
 	}
 
-	/// Add signed private transaction into the store
-	/// Creates corresponding public transaction if last required singature collected and sends it to the chain
-	pub fn import_signed_private_transaction(&self, rlp: &[u8]) -> Result<(), Error> {
-		let tx: SignedPrivateTransaction = Rlp::new(rlp).as_val()?;
-		trace!("Signature for private transaction received: {:?}", tx);
-		let private_hash = tx.private_transaction_hash();
-		let desc = match self.transactions_for_signing.lock().get(&private_hash) {
-			None => {
-				// TODO [ToDr] Verification (we can't just blindly forward every transaction)
-
-				// Not our transaction, broadcast further to peers
-				self.broadcast_signed_private_transaction(rlp.into());
-				return Ok(());
-			},
-			Some(desc) => desc,
-		};
-
-		let last = self.last_required_signature(&desc, tx.signature())?;
-
-		if last {
-			let mut signatures = desc.received_signatures.clone();
-			signatures.push(tx.signature());
-			let rsv: Vec<Signature> = signatures.into_iter().map(|sign| sign.into_electrum().into()).collect();
-			//Create public transaction
-			let public_tx = self.public_transaction(
-				desc.state.clone(),
-				&desc.original_transaction,
-				&rsv,
-				desc.original_transaction.nonce,
-				desc.original_transaction.gas_price
-			)?;
-			trace!("Last required signature received, public transaction created: {:?}", public_tx);
-			//Sign and add it to the queue
-			let chain_id = desc.original_transaction.chain_id();
-			let hash = public_tx.hash(chain_id);
-			let signer_account = self.signer_account.ok_or_else(|| ErrorKind::SignerAccountNotSet)?;
-			let password = find_account_password(&self.passwords, &*self.accounts, &signer_account);
-			let signature = self.accounts.sign(signer_account, password, hash)?;
-			let signed = SignedTransaction::new(public_tx.with_signature(signature, chain_id))?;
-			match self.miner.import_own_transaction(&*self.client, signed.into()) {
-				Ok(_) => trace!("Public transaction added to queue"),
-				Err(err) => {
-					trace!("Failed to add transaction to queue, error: {:?}", err);
-					bail!(err);
-				}
-			}
-			//Remove from store for signing
-			match self.transactions_for_signing.lock().remove(&private_hash) {
-				Ok(_) => {}
-				Err(err) => {
-					trace!("Failed to remove transaction from signing store, error: {:?}", err);
-					bail!(err);
-				}
-			}
-		} else {
-			//Add signature to the store
-			match self.transactions_for_signing.lock().add_signature(&private_hash, tx.signature()) {
-				Ok(_) => trace!("Signature stored for private transaction"),
-				Err(err) => {
-					trace!("Failed to add signature to signing store, error: {:?}", err);
-					bail!(err);
-				}
-			}
-		}
-		Ok(())
-	}
-
 	fn last_required_signature(&self, desc: &PrivateTransactionSigningDesc, sign: Signature) -> Result<bool, Error>  {
 		if desc.received_signatures.contains(&sign) {
 			return Ok(false);
@@ -657,6 +541,134 @@ impl Provider where {
 	}
 }
 
+pub trait Importer {
+	/// Process received private transaction
+	fn import_private_transaction(&self, _rlp: &[u8]) -> Result<(), Error>;
+
+	/// Add signed private transaction into the store
+	///
+	/// Creates corresponding public transaction if last required signature collected and sends it to the chain
+	fn import_signed_private_transaction(&self, _rlp: &[u8]) -> Result<(), Error>;
+}
+
+// TODO [ToDr] Offload more heavy stuff to the IoService thread.
+// It seems that a lot of heavy work (verification) is done in this thread anyway
+// it might actually make sense to decouple it from clientService and just use dedicated thread
+// for both verification and execution.
+
+impl Importer for Arc<Provider> {
+	fn import_private_transaction(&self, rlp: &[u8]) -> Result<(), Error> {
+		trace!("Private transaction received");
+		let private_tx: PrivateTransaction = Rlp::new(rlp).as_val()?;
+		let contract = private_tx.contract;
+		let contract_validators = self.get_validators(BlockId::Latest, &contract)?;
+
+		let validation_account = contract_validators
+			.iter()
+			.find(|address| self.validator_accounts.contains(address));
+
+		match validation_account {
+			None => {
+				// TODO [ToDr] This still seems a bit invalid, imho we should still import the transaction to the pool.
+				// Importing to pool verifies correctness and nonce; here we are just blindly forwarding.
+				//
+				// Not for verification, broadcast further to peers
+				self.broadcast_private_transaction(rlp.into());
+				return Ok(());
+			},
+			Some(&validation_account) => {
+				let hash = private_tx.hash();
+				trace!("Private transaction taken for verification");
+				let original_tx = self.extract_original_transaction(private_tx, &contract)?;
+				trace!("Validating transaction: {:?}", original_tx);
+				// Verify with the first account available
+				trace!("The following account will be used for verification: {:?}", validation_account);
+				let nonce_cache = Default::default();
+				self.transactions_for_verification.lock().add_transaction(
+					original_tx,
+					contract,
+					validation_account,
+					hash,
+					self.pool_client(&nonce_cache),
+				)?;
+				let provider = Arc::downgrade(self);
+				self.channel.send(ClientIoMessage::execute(move |_| {
+					if let Some(provider) = provider.upgrade() {
+						if let Err(e) = provider.process_queue() {
+							debug!("Unable to process the queue: {}", e);
+						}
+					}
+				})).map_err(|_| ErrorKind::ClientIsMalformed.into())
+			}
+		}
+	}
+
+	fn import_signed_private_transaction(&self, rlp: &[u8]) -> Result<(), Error> {
+		let tx: SignedPrivateTransaction = Rlp::new(rlp).as_val()?;
+		trace!("Signature for private transaction received: {:?}", tx);
+		let private_hash = tx.private_transaction_hash();
+		let desc = match self.transactions_for_signing.lock().get(&private_hash) {
+			None => {
+				// TODO [ToDr] Verification (we can't just blindly forward every transaction)
+
+				// Not our transaction, broadcast further to peers
+				self.broadcast_signed_private_transaction(rlp.into());
+				return Ok(());
+			},
+			Some(desc) => desc,
+		};
+
+		let last = self.last_required_signature(&desc, tx.signature())?;
+
+		if last {
+			let mut signatures = desc.received_signatures.clone();
+			signatures.push(tx.signature());
+			let rsv: Vec<Signature> = signatures.into_iter().map(|sign| sign.into_electrum().into()).collect();
+			//Create public transaction
+			let public_tx = self.public_transaction(
+				desc.state.clone(),
+				&desc.original_transaction,
+				&rsv,
+				desc.original_transaction.nonce,
+				desc.original_transaction.gas_price
+			)?;
+			trace!("Last required signature received, public transaction created: {:?}", public_tx);
+			//Sign and add it to the queue
+			let chain_id = desc.original_transaction.chain_id();
+			let hash = public_tx.hash(chain_id);
+			let signer_account = self.signer_account.ok_or_else(|| ErrorKind::SignerAccountNotSet)?;
+			let password = find_account_password(&self.passwords, &*self.accounts, &signer_account);
+			let signature = self.accounts.sign(signer_account, password, hash)?;
+			let signed = SignedTransaction::new(public_tx.with_signature(signature, chain_id))?;
+			match self.miner.import_own_transaction(&*self.client, signed.into()) {
+				Ok(_) => trace!("Public transaction added to queue"),
+				Err(err) => {
+					trace!("Failed to add transaction to queue, error: {:?}", err);
+					bail!(err);
+				}
+			}
+			//Remove from store for signing
+			match self.transactions_for_signing.lock().remove(&private_hash) {
+				Ok(_) => {}
+				Err(err) => {
+					trace!("Failed to remove transaction from signing store, error: {:?}", err);
+					bail!(err);
+				}
+			}
+		} else {
+			//Add signature to the store
+			match self.transactions_for_signing.lock().add_signature(&private_hash, tx.signature()) {
+				Ok(_) => trace!("Signature stored for private transaction"),
+				Err(err) => {
+					trace!("Failed to add signature to signing store, error: {:?}", err);
+					bail!(err);
+				}
+			}
+		}
+		Ok(())
+	}
+}
+
 /// Try to unlock account using stored password, return found password if any
 fn find_account_password(passwords: &Vec<String>, account_provider: &AccountProvider, account: &Address) -> Option<String> {
 	for password in passwords {

ethcore/private-tx/tests/private_contract.rs

@@ -74,7 +74,7 @@ fn private_contract() {
 			Box::new(NoopEncryptor::default()),
 			config,
 			io,
-	).unwrap());
+	));
 
 	let (address, _) = contract_address(CreateContractAddress::FromSenderAndNonce, &key1.address(), &0.into(), &[]);
 

ethcore/service/Cargo.toml

@@ -13,6 +13,7 @@ ethcore-sync = { path = "../sync" }
 kvdb = { path = "../../util/kvdb" }
 log = "0.3"
 stop-guard = { path = "../../util/stop-guard" }
+trace-time = { path = "../../util/trace-time" }
 
 [dev-dependencies]
 tempdir = "0.3"

ethcore/service/src/lib.rs

@@ -28,6 +28,9 @@ extern crate error_chain;
 #[macro_use]
 extern crate log;
 
+#[macro_use]
+extern crate trace_time;
+
 #[cfg(test)]
 extern crate tempdir;
 

ethcore/service/src/service.rs

@@ -33,7 +33,7 @@ use ethcore::snapshot::{RestorationStatus};
 use ethcore::spec::Spec;
 use ethcore::account_provider::AccountProvider;
 
-use ethcore_private_tx;
+use ethcore_private_tx::{self, Importer};
 use Error;
 
 pub struct PrivateTxService {
@@ -112,14 +112,13 @@ impl ClientService {
 				account_provider,
 				encryptor,
 				private_tx_conf,
-				io_service.channel())?,
+				io_service.channel(),
-		);
+		));
 		let private_tx = Arc::new(PrivateTxService::new(provider));
 
 		let client_io = Arc::new(ClientIoHandler {
 			client: client.clone(),
 			snapshot: snapshot.clone(),
-			private_tx: private_tx.clone(),
 		});
 		io_service.register_handler(client_io)?;
 
@@ -175,7 +174,6 @@ impl ClientService {
 struct ClientIoHandler {
 	client: Arc<Client>,
 	snapshot: Arc<SnapshotService>,
-	private_tx: Arc<PrivateTxService>,
 }
 
 const CLIENT_TICK_TIMER: TimerToken = 0;
@@ -191,6 +189,7 @@ impl IoHandler<ClientIoMessage> for ClientIoHandler {
 	}
 
 	fn timeout(&self, _io: &IoContext<ClientIoMessage>, timer: TimerToken) {
+		trace_time!("service::read");
 		match timer {
 			CLIENT_TICK_TIMER => {
 				use ethcore::snapshot::SnapshotService;
@@ -203,20 +202,24 @@ impl IoHandler<ClientIoMessage> for ClientIoHandler {
 	}
 
 	fn message(&self, _io: &IoContext<ClientIoMessage>, net_message: &ClientIoMessage) {
+		trace_time!("service::message");
 		use std::thread;
 
 		match *net_message {
-			ClientIoMessage::BlockVerified => { self.client.import_verified_blocks(); }
+			ClientIoMessage::BlockVerified => {
-			ClientIoMessage::NewTransactions(ref transactions, peer_id) => {
+				self.client.import_verified_blocks();
-				self.client.import_queued_transactions(transactions, peer_id);
 			}
 			ClientIoMessage::BeginRestoration(ref manifest) => {
 				if let Err(e) = self.snapshot.init_restore(manifest.clone(), true) {
 					warn!("Failed to initialize snapshot restoration: {}", e);
 				}
 			}
-			ClientIoMessage::FeedStateChunk(ref hash, ref chunk) => self.snapshot.feed_state_chunk(*hash, chunk),
+			ClientIoMessage::FeedStateChunk(ref hash, ref chunk) => {
-			ClientIoMessage::FeedBlockChunk(ref hash, ref chunk) => self.snapshot.feed_block_chunk(*hash, chunk),
+				self.snapshot.feed_state_chunk(*hash, chunk)
+			}
+			ClientIoMessage::FeedBlockChunk(ref hash, ref chunk) => {
+				self.snapshot.feed_block_chunk(*hash, chunk)
+			}
 			ClientIoMessage::TakeSnapshot(num) => {
 				let client = self.client.clone();
 				let snapshot = self.snapshot.clone();
@@ -231,12 +234,9 @@ impl IoHandler<ClientIoMessage> for ClientIoHandler {
 					debug!(target: "snapshot", "Failed to initialize periodic snapshot thread: {:?}", e);
 				}
 			},
-			ClientIoMessage::NewMessage(ref message) => if let Err(e) = self.client.engine().handle_message(message) {
+			ClientIoMessage::Execute(ref exec) => {
-				trace!(target: "poa", "Invalid message received: {}", e);
+				(*exec.0)(&self.client);
-			},
+			}
-			ClientIoMessage::NewPrivateTransaction => if let Err(e) = self.private_tx.provider.on_private_transaction_queued() {
-				warn!("Failed to handle private transaction {:?}", e);
-			},
 			_ => {} // ignore other messages
 		}
 	}

ethcore/src/client/ancient_import.rs

@@ -32,16 +32,16 @@ const HEAVY_VERIFY_RATE: f32 = 0.02;
 /// Ancient block verifier: import an ancient sequence of blocks in order from a starting
 /// epoch.
 pub struct AncientVerifier {
-	cur_verifier: RwLock<Box<EpochVerifier<EthereumMachine>>>,
+	cur_verifier: RwLock<Option<Box<EpochVerifier<EthereumMachine>>>>,
 	engine: Arc<EthEngine>,
 }
 
 impl AncientVerifier {
-	/// Create a new ancient block verifier with the given engine and initial verifier.
+	/// Create a new ancient block verifier with the given engine.
-	pub fn new(engine: Arc<EthEngine>, start_verifier: Box<EpochVerifier<EthereumMachine>>) -> Self {
+	pub fn new(engine: Arc<EthEngine>) -> Self {
 		AncientVerifier {
-			cur_verifier: RwLock::new(start_verifier),
+			cur_verifier: RwLock::new(None),
-			engine: engine,
+			engine,
 		}
 	}
 
@@ -53,17 +53,49 @@ impl AncientVerifier {
 		header: &Header,
 		chain: &BlockChain,
 	) -> Result<(), ::error::Error> {
+		// perform verification
+		let verified = if let Some(ref cur_verifier) = *self.cur_verifier.read() {
 			match rng.gen::<f32>() <= HEAVY_VERIFY_RATE {
-			true => self.cur_verifier.read().verify_heavy(header)?,
+				true => cur_verifier.verify_heavy(header)?,
-			false => self.cur_verifier.read().verify_light(header)?,
+				false => cur_verifier.verify_light(header)?,
+			}
+			true
+		} else {
+			false
+		};
+
+		// when there is no verifier initialize it.
+		// We use a bool flag to avoid double locking in the happy case
+		if !verified {
+			{
+				let mut cur_verifier = self.cur_verifier.write();
+				if cur_verifier.is_none() {
+					*cur_verifier = Some(self.initial_verifier(header, chain)?);
+				}
+			}
+			// Call again to verify.
+			return self.verify(rng, header, chain);
 		}
 
 		// ancient import will only use transitions obtained from the snapshot.
 		if let Some(transition) = chain.epoch_transition(header.number(), header.hash()) {
 			let v = self.engine.epoch_verifier(&header, &transition.proof).known_confirmed()?;
-			*self.cur_verifier.write() = v;
+			*self.cur_verifier.write() = Some(v);
 		}
 
 		Ok(())
 	}
+
+	fn initial_verifier(&self, header: &Header, chain: &BlockChain)
+		-> Result<Box<EpochVerifier<EthereumMachine>>, ::error::Error>
+	{
+		trace!(target: "client", "Initializing ancient block restoration.");
+		let current_epoch_data = chain.epoch_transitions()
+			.take_while(|&(_, ref t)| t.block_number < header.number())
+			.last()
+			.map(|(_, t)| t.proof)
+			.expect("At least one epoch entry (genesis) always stored; qed");
+
+		self.engine.epoch_verifier(&header, &current_epoch_data).known_confirmed()
+	}
 }

ethcore/src/client/client.rs

@@ -15,15 +15,16 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use std::collections::{HashSet, BTreeMap, BTreeSet, VecDeque};
+use std::fmt;
 use std::str::FromStr;
-use std::sync::{Arc, Weak};
 use std::sync::atomic::{AtomicUsize, AtomicBool, Ordering as AtomicOrdering};
+use std::sync::{Arc, Weak};
 use std::time::{Instant, Duration};
-use itertools::Itertools;
 
 // util
 use hash::keccak;
 use bytes::Bytes;
+use itertools::Itertools;
 use journaldb;
 use trie::{TrieSpec, TrieFactory, Trie};
 use kvdb::{DBValue, KeyValueDB, DBTransaction};
@@ -45,7 +46,8 @@ use client::{
 use client::{
 	BlockId, TransactionId, UncleId, TraceId, ClientConfig, BlockChainClient,
 	TraceFilter, CallAnalytics, BlockImportError, Mode,
-	ChainNotify, ChainRoute, PruningInfo, ProvingBlockChainClient, EngineInfo, ChainMessageType
+	ChainNotify, ChainRoute, PruningInfo, ProvingBlockChainClient, EngineInfo, ChainMessageType,
+	IoClient,
 };
 use encoded;
 use engines::{EthEngine, EpochTransition};
@@ -55,7 +57,7 @@ use evm::Schedule;
 use executive::{Executive, Executed, TransactOptions, contract_address};
 use factory::{Factories, VmFactory};
 use header::{BlockNumber, Header};
-use io::IoChannel;
+use io::{IoChannel, IoError};
 use log_entry::LocalizedLogEntry;
 use miner::{Miner, MinerService};
 use ethcore_miner::pool::VerifiedTransaction;
@@ -85,6 +87,7 @@ pub use verification::queue::QueueInfo as BlockQueueInfo;
 use_contract!(registry, "Registry", "res/contracts/registrar.json");
 
 const MAX_TX_QUEUE_SIZE: usize = 4096;
+const MAX_ANCIENT_BLOCKS_QUEUE_SIZE: usize = 4096;
 const MAX_QUEUE_SIZE_TO_SLEEP_ON: usize = 2;
 const MIN_HISTORY_SIZE: u64 = 8;
 
@@ -154,10 +157,7 @@ struct Importer {
 	pub miner: Arc<Miner>,
 
 	/// Ancient block verifier: import an ancient sequence of blocks in order from a starting epoch
-	pub ancient_verifier: Mutex<Option<AncientVerifier>>,
+	pub ancient_verifier: AncientVerifier,
-
-	/// Random number generator used by `AncientVerifier`
-	pub rng: Mutex<OsRng>,
 
 	/// Ethereum engine to be used during import
 	pub engine: Arc<EthEngine>,
@@ -204,8 +204,13 @@ pub struct Client {
 	/// List of actors to be notified on certain chain events
 	notify: RwLock<Vec<Weak<ChainNotify>>>,
 
-	/// Count of pending transactions in the queue
+	/// Queued transactions from IO
-	queue_transactions: AtomicUsize,
+	queue_transactions: IoChannelQueue,
+	/// Ancient blocks import queue
+	queue_ancient_blocks: IoChannelQueue,
+	/// Consensus messages import queue
+	queue_consensus_message: IoChannelQueue,
+
 	last_hashes: RwLock<VecDeque<H256>>,
 	factories: Factories,
 
@@ -239,8 +244,7 @@ impl Importer {
 			verifier: verification::new(config.verifier_type.clone()),
 			block_queue,
 			miner,
-			ancient_verifier: Mutex::new(None),
+			ancient_verifier: AncientVerifier::new(engine.clone()),
-			rng: Mutex::new(OsRng::new()?),
 			engine,
 		})
 	}
@@ -416,55 +420,25 @@ impl Importer {
 		Ok(locked_block)
 	}
 
+
 	/// Import a block with transaction receipts.
 	///
 	/// The block is guaranteed to be the next best blocks in the
 	/// first block sequence. Does no sealing or transaction validation.
-	fn import_old_block(&self, header: &Header, block_bytes: Bytes, receipts_bytes: Bytes, db: &KeyValueDB, chain: &BlockChain) -> Result<H256, ::error::Error> {
+	fn import_old_block(&self, header: &Header, block_bytes: &[u8], receipts_bytes: &[u8], db: &KeyValueDB, chain: &BlockChain) -> Result<H256, ::error::Error> {
-		let receipts = ::rlp::decode_list(&receipts_bytes);
+		let receipts = ::rlp::decode_list(receipts_bytes);
 		let hash = header.hash();
 		let _import_lock = self.import_lock.lock();
 
 		{
 			trace_time!("import_old_block");
-			let mut ancient_verifier = self.ancient_verifier.lock();
+			// verify the block, passing the chain for updating the epoch verifier.
-
-			{
-				// closure for verifying a block.
-				let verify_with = |verifier: &AncientVerifier| -> Result<(), ::error::Error> {
-					// verify the block, passing the chain for updating the epoch
-					// verifier.
 			let mut rng = OsRng::new().map_err(UtilError::from)?;
-					verifier.verify(&mut rng, &header, &chain)
+			self.ancient_verifier.verify(&mut rng, &header, &chain)?;
-				};
-
-				// initialize the ancient block verifier if we don't have one already.
-				match &mut *ancient_verifier {
-					&mut Some(ref verifier) => {
-						verify_with(verifier)?
-					}
-					x @ &mut None => {
-						// load most recent epoch.
-						trace!(target: "client", "Initializing ancient block restoration.");
-						let current_epoch_data = chain.epoch_transitions()
-							.take_while(|&(_, ref t)| t.block_number < header.number())
-							.last()
-							.map(|(_, t)| t.proof)
-							.expect("At least one epoch entry (genesis) always stored; qed");
-
-						let current_verifier = self.engine.epoch_verifier(&header, &current_epoch_data)
-							.known_confirmed()?;
-						let current_verifier = AncientVerifier::new(self.engine.clone(), current_verifier);
-
-						verify_with(&current_verifier)?;
-						*x = Some(current_verifier);
-					}
-				}
-			}
 
 			// Commit results
 			let mut batch = DBTransaction::new();
-			chain.insert_unordered_block(&mut batch, &block_bytes, receipts, None, false, true);
+			chain.insert_unordered_block(&mut batch, block_bytes, receipts, None, false, true);
 			// Final commit to the DB
 			db.write_buffered(batch);
 			chain.commit();
@@ -734,7 +708,9 @@ impl Client {
 			report: RwLock::new(Default::default()),
 			io_channel: Mutex::new(message_channel),
 			notify: RwLock::new(Vec::new()),
-			queue_transactions: AtomicUsize::new(0),
+			queue_transactions: IoChannelQueue::new(MAX_TX_QUEUE_SIZE),
+			queue_ancient_blocks: IoChannelQueue::new(MAX_ANCIENT_BLOCKS_QUEUE_SIZE),
+			queue_consensus_message: IoChannelQueue::new(usize::max_value()),
 			last_hashes: RwLock::new(VecDeque::new()),
 			factories: factories,
 			history: history,
@@ -820,7 +796,7 @@ impl Client {
 	}
 
 	fn notify<F>(&self, f: F) where F: Fn(&ChainNotify) {
-		for np in self.notify.read().iter() {
+		for np in &*self.notify.read() {
 			if let Some(n) = np.upgrade() {
 				f(&*n);
 			}
@@ -954,24 +930,6 @@ impl Client {
 		}
 	}
 
-	/// Import transactions from the IO queue
-	pub fn import_queued_transactions(&self, transactions: &[Bytes], peer_id: usize) -> usize {
-		trace_time!("import_queued_transactions");
-		self.queue_transactions.fetch_sub(transactions.len(), AtomicOrdering::SeqCst);
-
-		let txs: Vec<UnverifiedTransaction> = transactions
-			.iter()
-			.filter_map(|bytes| self.engine().decode_transaction(bytes).ok())
-			.collect();
-
-		self.notify(|notify| {
-			notify.transactions_received(&txs, peer_id);
-		});
-
-		let results = self.importer.miner.import_external_transactions(self, txs);
-		results.len()
-	}
-
 	/// Get shared miner reference.
 	#[cfg(test)]
 	pub fn miner(&self) -> Arc<Miner> {
@@ -1392,22 +1350,6 @@ impl ImportBlock for Client {
 		}
 		Ok(self.importer.block_queue.import(unverified)?)
 	}
-
-	fn import_block_with_receipts(&self, block_bytes: Bytes, receipts_bytes: Bytes) -> Result<H256, BlockImportError> {
-		let header: Header = ::rlp::Rlp::new(&block_bytes).val_at(0)?;
-		{
-			// check block order
-			if self.chain.read().is_known(&header.hash()) {
-				bail!(BlockImportErrorKind::Import(ImportErrorKind::AlreadyInChain));
-			}
-			let status = self.block_status(BlockId::Hash(*header.parent_hash()));
-			if status == BlockStatus::Unknown || status == BlockStatus::Pending {
-				bail!(BlockImportErrorKind::Block(BlockError::UnknownParent(*header.parent_hash())));
-			}
-		}
-
-		self.importer.import_old_block(&header, block_bytes, receipts_bytes, &**self.db.read(), &*self.chain.read()).map_err(Into::into)
-	}
 }
 
 impl StateClient for Client {
@@ -1958,35 +1900,10 @@ impl BlockChainClient for Client {
 		(*self.build_last_hashes(&self.chain.read().best_block_hash())).clone()
 	}
 
-	fn queue_transactions(&self, transactions: Vec<Bytes>, peer_id: usize) {
-		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();
-			match self.io_channel.lock().send(ClientIoMessage::NewTransactions(transactions, peer_id)) {
-				Ok(_) => {
-					self.queue_transactions.fetch_add(len, AtomicOrdering::SeqCst);
-				}
-				Err(e) => {
-					debug!("Ignoring {} transactions: error queueing: {}", len, e);
-				}
-			}
-		}
-	}
-
 	fn ready_transactions(&self) -> Vec<Arc<VerifiedTransaction>> {
 		self.importer.miner.ready_transactions(self)
 	}
 
-	fn queue_consensus_message(&self, message: Bytes) {
-		let channel = self.io_channel.lock().clone();
-		if let Err(e) = channel.send(ClientIoMessage::NewMessage(message)) {
-			debug!("Ignoring the message, error queueing: {}", e);
-		}
-	}
-
 	fn signing_chain_id(&self) -> Option<u64> {
 		self.engine.signing_chain_id(&self.latest_env_info())
 	}
@@ -2034,6 +1951,72 @@ impl BlockChainClient for Client {
 	}
 }
 
+impl IoClient for Client {
+	fn queue_transactions(&self, transactions: Vec<Bytes>, peer_id: usize) {
+		let len = transactions.len();
+		self.queue_transactions.queue(&mut self.io_channel.lock(), len, move |client| {
+			trace_time!("import_queued_transactions");
+
+			let txs: Vec<UnverifiedTransaction> = transactions
+				.iter()
+				.filter_map(|bytes| client.engine.decode_transaction(bytes).ok())
+				.collect();
+
+			client.notify(|notify| {
+				notify.transactions_received(&txs, peer_id);
+			});
+
+			client.importer.miner.import_external_transactions(client, txs);
+		}).unwrap_or_else(|e| {
+			debug!(target: "client", "Ignoring {} transactions: {}", len, e);
+		});
+	}
+
+	fn queue_ancient_block(&self, block_bytes: Bytes, receipts_bytes: Bytes) -> Result<H256, BlockImportError> {
+		let header: Header = ::rlp::Rlp::new(&block_bytes).val_at(0)?;
+		let hash = header.hash();
+
+		{
+			// check block order
+			if self.chain.read().is_known(&header.hash()) {
+				bail!(BlockImportErrorKind::Import(ImportErrorKind::AlreadyInChain));
+			}
+			let status = self.block_status(BlockId::Hash(*header.parent_hash()));
+			if  status == BlockStatus::Unknown || status == BlockStatus::Pending {
+				bail!(BlockImportErrorKind::Block(BlockError::UnknownParent(*header.parent_hash())));
+			}
+		}
+
+		match self.queue_ancient_blocks.queue(&mut self.io_channel.lock(), 1, move |client| {
+			client.importer.import_old_block(
+				&header,
+				&block_bytes,
+				&receipts_bytes,
+				&**client.db.read(),
+				&*client.chain.read()
+			).map(|_| ()).unwrap_or_else(|e| {
+				error!(target: "client", "Error importing ancient block: {}", e);
+			});
+		}) {
+			Ok(_) => Ok(hash),
+			Err(e) => bail!(BlockImportErrorKind::Other(format!("{}", e))),
+		}
+	}
+
+	fn queue_consensus_message(&self, message: Bytes) {
+		match self.queue_consensus_message.queue(&mut self.io_channel.lock(), 1, move |client| {
+			if let Err(e) = client.engine().handle_message(&message) {
+				debug!(target: "poa", "Invalid message received: {}", e);
+			}
+		}) {
+			Ok(_) => (),
+			Err(e) => {
+				debug!(target: "poa", "Ignoring the message, error queueing: {}", e);
+			}
+		}
+	}
+}
+
 impl ReopenBlock for Client {
 	fn reopen_block(&self, block: ClosedBlock) -> OpenBlock {
 		let engine = &*self.engine;
@@ -2409,3 +2392,54 @@ mod tests {
 		});
 	}
 }
+
+#[derive(Debug)]
+enum QueueError {
+	Channel(IoError),
+	Full(usize),
+}
+
+impl fmt::Display for QueueError {
+	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+		match *self {
+			QueueError::Channel(ref c) => fmt::Display::fmt(c, fmt),
+			QueueError::Full(limit) => write!(fmt, "The queue is full ({})", limit),
+		}
+	}
+}
+
+/// Queue some items to be processed by IO client.
+struct IoChannelQueue {
+	currently_queued: Arc<AtomicUsize>,
+	limit: usize,
+}
+
+impl IoChannelQueue {
+	pub fn new(limit: usize) -> Self {
+		IoChannelQueue {
+			currently_queued: Default::default(),
+			limit,
+		}
+	}
+
+	pub fn queue<F>(&self, channel: &mut IoChannel<ClientIoMessage>, count: usize, fun: F) -> Result<(), QueueError> where
+		F: Fn(&Client) + Send + Sync + 'static,
+	{
+		let queue_size = self.currently_queued.load(AtomicOrdering::Relaxed);
+		ensure!(queue_size < self.limit, QueueError::Full(self.limit));
+
+		let currently_queued = self.currently_queued.clone();
+		let result = channel.send(ClientIoMessage::execute(move |client| {
+			currently_queued.fetch_sub(count, AtomicOrdering::SeqCst);
+			fun(client);
+		}));
+
+		match result {
+			Ok(_) => {
+				self.currently_queued.fetch_add(count, AtomicOrdering::SeqCst);
+				Ok(())
+			},
+			Err(e) => Err(QueueError::Channel(e)),
+		}
+	}
+}

ethcore/src/client/io_message.rs

@@ -14,19 +14,19 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
-use ethereum_types::H256;
+use std::fmt;
 use bytes::Bytes;
+use client::Client;
+use ethereum_types::H256;
 use snapshot::ManifestData;
 
 /// Message type for external and internal events
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Debug)]
 pub enum ClientIoMessage {
 	/// Best Block Hash in chain has been changed
 	NewChainHead,
 	/// A block is ready
 	BlockVerified,
-	/// New transaction RLPs are ready to be imported
-	NewTransactions(Vec<Bytes>, usize),
 	/// Begin snapshot restoration
 	BeginRestoration(ManifestData),
 	/// Feed a state chunk to the snapshot service
@@ -35,9 +35,23 @@ pub enum ClientIoMessage {
 	FeedBlockChunk(H256, Bytes),
 	/// Take a snapshot for the block with given number.
 	TakeSnapshot(u64),
-	/// New consensus message received.
+	/// Execute wrapped closure
-	NewMessage(Bytes),
+	Execute(Callback),
-	/// New private transaction arrived
+}
-	NewPrivateTransaction,
+
+impl ClientIoMessage {
+	/// Create new `ClientIoMessage` that executes given procedure.
+	pub fn execute<F: Fn(&Client) + Send + Sync + 'static>(fun: F) -> Self {
+		ClientIoMessage::Execute(Callback(Box::new(fun)))
+	}
+}
+
+/// A function to invoke in the client thread.
+pub struct Callback(pub Box<Fn(&Client) + Send + Sync>);
+
+impl fmt::Debug for Callback {
+	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+		write!(fmt, "<callback>")
+	}
 }
 

ethcore/src/client/mod.rs

@@ -36,9 +36,8 @@ pub use self::traits::{
     Nonce, Balance, ChainInfo, BlockInfo, ReopenBlock, PrepareOpenBlock, CallContract, TransactionInfo, RegistryInfo, ScheduleInfo, ImportSealedBlock, BroadcastProposalBlock, ImportBlock,
     StateOrBlock, StateClient, Call, EngineInfo, AccountData, BlockChain, BlockProducer, SealedBlockImporter
 };
-//pub use self::private_notify::PrivateNotify;
 pub use state::StateInfo;
-pub use self::traits::{BlockChainClient, EngineClient, ProvingBlockChainClient};
+pub use self::traits::{BlockChainClient, EngineClient, ProvingBlockChainClient, IoClient};
 
 pub use types::ids::*;
 pub use types::trace_filter::Filter as TraceFilter;

ethcore/src/client/test_client.rs

@@ -39,7 +39,7 @@ use client::{
 	PrepareOpenBlock, BlockChainClient, BlockChainInfo, BlockStatus, BlockId,
 	TransactionId, UncleId, TraceId, TraceFilter, LastHashes, CallAnalytics, BlockImportError,
 	ProvingBlockChainClient, ScheduleInfo, ImportSealedBlock, BroadcastProposalBlock, ImportBlock, StateOrBlock,
-	Call, StateClient, EngineInfo, AccountData, BlockChain, BlockProducer, SealedBlockImporter
+	Call, StateClient, EngineInfo, AccountData, BlockChain, BlockProducer, SealedBlockImporter, IoClient
 };
 use db::{NUM_COLUMNS, COL_STATE};
 use header::{Header as BlockHeader, BlockNumber};
@@ -556,10 +556,6 @@ impl ImportBlock for TestBlockChainClient {
 		}
 		Ok(h)
 	}
-
-	fn import_block_with_receipts(&self, b: Bytes, _r: Bytes) -> Result<H256, BlockImportError> {
-		self.import_block(b)
-	}
 }
 
 impl Call for TestBlockChainClient {
@@ -809,16 +805,6 @@ impl BlockChainClient for TestBlockChainClient {
 		self.traces.read().clone()
 	}
 
-	fn queue_transactions(&self, transactions: Vec<Bytes>, _peer_id: usize) {
-		// import right here
-		let txs = transactions.into_iter().filter_map(|bytes| Rlp::new(&bytes).as_val().ok()).collect();
-		self.miner.import_external_transactions(self, txs);
-	}
-
-	fn queue_consensus_message(&self, message: Bytes) {
-		self.spec.engine.handle_message(&message).unwrap();
-	}
-
 	fn ready_transactions(&self) -> Vec<Arc<VerifiedTransaction>> {
 		self.miner.ready_transactions(self)
 	}
@@ -863,6 +849,22 @@ impl BlockChainClient for TestBlockChainClient {
 	fn eip86_transition(&self) -> u64 { u64::max_value() }
 }
 
+impl IoClient for TestBlockChainClient {
+	fn queue_transactions(&self, transactions: Vec<Bytes>, _peer_id: usize) {
+		// import right here
+		let txs = transactions.into_iter().filter_map(|bytes| Rlp::new(&bytes).as_val().ok()).collect();
+		self.miner.import_external_transactions(self, txs);
+	}
+
+	fn queue_ancient_block(&self, b: Bytes, _r: Bytes) -> Result<H256, BlockImportError> {
+		self.import_block(b)
+	}
+
+	fn queue_consensus_message(&self, message: Bytes) {
+		self.spec.engine.handle_message(&message).unwrap();
+	}
+}
+
 impl ProvingBlockChainClient for TestBlockChainClient {
 	fn prove_storage(&self, _: H256, _: H256, _: BlockId) -> Option<(Vec<Bytes>, H256)> {
 		None

ethcore/src/client/traits.rs

@@ -168,9 +168,6 @@ pub trait RegistryInfo {
 pub trait ImportBlock {
 	/// Import a block into the blockchain.
 	fn import_block(&self, bytes: Bytes) -> Result<H256, BlockImportError>;
-
-	/// Import a block with transaction receipts. Does no sealing and transaction validation.
-	fn import_block_with_receipts(&self, block_bytes: Bytes, receipts_bytes: Bytes) -> Result<H256, BlockImportError>;
 }
 
 /// Provides `call_contract` method
@@ -201,8 +198,21 @@ pub trait EngineInfo {
 	fn engine(&self) -> &EthEngine;
 }
 
+/// IO operations that should off-load heavy work to another thread.
+pub trait IoClient: Sync + Send {
+	/// Queue transactions for importing.
+	fn queue_transactions(&self, transactions: Vec<Bytes>, peer_id: usize);
+
+	/// Queue block import with transaction receipts. Does no sealing and transaction validation.
+	fn queue_ancient_block(&self, block_bytes: Bytes, receipts_bytes: Bytes) -> Result<H256, BlockImportError>;
+
+	/// Queue conensus engine message.
+	fn queue_consensus_message(&self, message: Bytes);
+}
+
 /// Blockchain database client. Owns and manages a blockchain and a block queue.
-pub trait BlockChainClient : Sync + Send + AccountData + BlockChain + CallContract + RegistryInfo + ImportBlock {
+pub trait BlockChainClient : Sync + Send + AccountData + BlockChain + CallContract + RegistryInfo + ImportBlock
++ IoClient {
 	/// Look up the block number for the given block ID.
 	fn block_number(&self, id: BlockId) -> Option<BlockNumber>;
 
@@ -310,12 +320,6 @@ pub trait BlockChainClient : Sync + Send + AccountData + BlockChain + CallContra
 	/// Get last hashes starting from best block.
 	fn last_hashes(&self) -> LastHashes;
 
-	/// Queue transactions for importing.
-	fn queue_transactions(&self, transactions: Vec<Bytes>, peer_id: usize);
-
-	/// Queue conensus engine message.
-	fn queue_consensus_message(&self, message: Bytes);
-
 	/// List all transactions that are allowed into the next block.
 	fn ready_transactions(&self) -> Vec<Arc<VerifiedTransaction>>;
 

ethcore/src/views/block.rs

@@ -29,7 +29,6 @@ pub struct BlockView<'a> {
 	rlp: ViewRlp<'a>
 }
 
-
 impl<'a> BlockView<'a> {
 	/// Creates new view onto block from rlp.
 	/// Use the `view!` macro to create this view in order to capture debugging info.

ethcore/sync/Cargo.toml

@@ -30,6 +30,7 @@ heapsize = "0.4"
 semver = "0.9"
 smallvec = { version = "0.4", features = ["heapsizeof"] }
 parking_lot = "0.5"
+trace-time = { path = "../../util/trace-time" }
 ipnetwork = "0.12.6"
 
 [dev-dependencies]

ethcore/sync/src/api.rs

@@ -379,10 +379,12 @@ impl NetworkProtocolHandler for SyncProtocolHandler {
 	}
 
 	fn read(&self, io: &NetworkContext, peer: &PeerId, packet_id: u8, data: &[u8]) {
+		trace_time!("sync::read");
 		ChainSync::dispatch_packet(&self.sync, &mut NetSyncIo::new(io, &*self.chain, &*self.snapshot_service, &self.overlay), *peer, packet_id, data);
 	}
 
 	fn connected(&self, io: &NetworkContext, peer: &PeerId) {
+		trace_time!("sync::connected");
 		// If warp protocol is supported only allow warp handshake
 		let warp_protocol = io.protocol_version(WARP_SYNC_PROTOCOL_ID, *peer).unwrap_or(0) != 0;
 		let warp_context = io.subprotocol_name() == WARP_SYNC_PROTOCOL_ID;
@@ -392,12 +394,14 @@ impl NetworkProtocolHandler for SyncProtocolHandler {
 	}
 
 	fn disconnected(&self, io: &NetworkContext, peer: &PeerId) {
+		trace_time!("sync::disconnected");
 		if io.subprotocol_name() != WARP_SYNC_PROTOCOL_ID {
 			self.sync.write().on_peer_aborting(&mut NetSyncIo::new(io, &*self.chain, &*self.snapshot_service, &self.overlay), *peer);
 		}
 	}
 
 	fn timeout(&self, io: &NetworkContext, _timer: TimerToken) {
+		trace_time!("sync::timeout");
 		let mut io = NetSyncIo::new(io, &*self.chain, &*self.snapshot_service, &self.overlay);
 		self.sync.write().maintain_peers(&mut io);
 		self.sync.write().maintain_sync(&mut io);

ethcore/sync/src/block_sync.rs

@@ -496,7 +496,7 @@ impl BlockDownloader {
 			}
 
 			let result = if let Some(receipts) = receipts {
-				io.chain().import_block_with_receipts(block, receipts)
+				io.chain().queue_ancient_block(block, receipts)
 			} else {
 				io.chain().import_block(block)
 			};

ethcore/sync/src/chain.rs

@@ -1789,10 +1789,13 @@ impl ChainSync {
 	}
 
 	pub fn on_packet(&mut self, io: &mut SyncIo, peer: PeerId, packet_id: u8, data: &[u8]) {
+		debug!(target: "sync", "{} -> Dispatching packet: {}", peer, packet_id);
+
 		if packet_id != STATUS_PACKET && !self.peers.contains_key(&peer) {
 			debug!(target:"sync", "Unexpected packet {} from unregistered peer: {}:{}", packet_id, peer, io.peer_info(peer));
 			return;
 		}
+
 		let rlp = Rlp::new(data);
 		let result = match packet_id {
 			STATUS_PACKET => self.on_peer_status(io, peer, &rlp),
@@ -1831,7 +1834,7 @@ impl ChainSync {
 				PeerAsking::SnapshotData => elapsed > SNAPSHOT_DATA_TIMEOUT,
 			};
 			if timeout {
-				trace!(target:"sync", "Timeout {}", peer_id);
+				debug!(target:"sync", "Timeout {}", peer_id);
 				io.disconnect_peer(*peer_id);
 				aborting.push(*peer_id);
 			}

ethcore/sync/src/lib.rs

@@ -54,6 +54,8 @@ extern crate macros;
 extern crate log;
 #[macro_use]
 extern crate heapsize;
+#[macro_use]
+extern crate trace_time;
 
 mod chain;
 mod blocks;

ethcore/sync/src/tests/helpers.rs

@@ -520,11 +520,9 @@ impl TestIoHandler {
 impl IoHandler<ClientIoMessage> for TestIoHandler {
 	fn message(&self, _io: &IoContext<ClientIoMessage>, net_message: &ClientIoMessage) {
 		match *net_message {
-			ClientIoMessage::NewMessage(ref message) => if let Err(e) = self.client.engine().handle_message(message) {
+			ClientIoMessage::Execute(ref exec) => {
-				panic!("Invalid message received: {}", e);
-			},
-			ClientIoMessage::NewPrivateTransaction => {
 				*self.private_tx_queued.lock() += 1;
+				(*exec.0)(&self.client);
 			},
 			_ => {} // ignore other messages
 		}

ethcore/sync/src/tests/private.rs

@@ -24,7 +24,7 @@ use ethcore::CreateContractAddress;
 use transaction::{Transaction, Action};
 use ethcore::executive::{contract_address};
 use ethcore::test_helpers::{push_block_with_transactions};
-use ethcore_private_tx::{Provider, ProviderConfig, NoopEncryptor};
+use ethcore_private_tx::{Provider, ProviderConfig, NoopEncryptor, Importer};
 use ethcore::account_provider::AccountProvider;
 use ethkey::{KeyPair};
 use tests::helpers::{TestNet, TestIoHandler};
@@ -84,7 +84,7 @@ fn send_private_transaction() {
 			Box::new(NoopEncryptor::default()),
 			signer_config,
 			IoChannel::to_handler(Arc::downgrade(&io_handler0)),
-	).unwrap());
+	));
 	pm0.add_notify(net.peers[0].clone());
 
 	let pm1 = Arc::new(Provider::new(
@@ -94,7 +94,7 @@ fn send_private_transaction() {
 			Box::new(NoopEncryptor::default()),
 			validator_config,
 			IoChannel::to_handler(Arc::downgrade(&io_handler1)),
-	).unwrap());
+	));
 	pm1.add_notify(net.peers[1].clone());
 
 	// Create and deploy contract
@@ -133,7 +133,6 @@ fn send_private_transaction() {
 	//process received private transaction message
 	let private_transaction = received_private_transactions[0].clone();
 	assert!(pm1.import_private_transaction(&private_transaction).is_ok());
-	assert!(pm1.on_private_transaction_queued().is_ok());
 
 	//send signed response
 	net.sync();

util/io/src/lib.rs

@@ -106,7 +106,7 @@ impl From<::std::io::Error> for IoError {
 	}
 }
 
-impl<Message> From<NotifyError<service::IoMessage<Message>>> for IoError where Message: Send + Clone {
+impl<Message> From<NotifyError<service::IoMessage<Message>>> for IoError where Message: Send {
 	fn from(_err: NotifyError<service::IoMessage<Message>>) -> IoError {
 		IoError::Mio(::std::io::Error::new(::std::io::ErrorKind::ConnectionAborted, "Network IO notification error"))
 	}
@@ -115,7 +115,7 @@ impl<Message> From<NotifyError<service::IoMessage<Message>>> for IoError where M
 /// Generic IO handler.
 /// All the handler function are called from within IO event loop.
 /// `Message` type is used as notification data
-pub trait IoHandler<Message>: Send + Sync where Message: Send + Sync + Clone + 'static {
+pub trait IoHandler<Message>: Send + Sync where Message: Send + Sync + 'static {
 	/// Initialize the handler
 	fn initialize(&self, _io: &IoContext<Message>) {}
 	/// Timer function called after a timeout created with `HandlerIo::timeout`.

util/io/src/service.rs

@@ -41,7 +41,7 @@ const MAX_HANDLERS: usize = 8;
 
 /// Messages used to communicate with the event loop from other threads.
 #[derive(Clone)]
-pub enum IoMessage<Message> where Message: Send + Clone + Sized {
+pub enum IoMessage<Message> where Message: Send + Sized {
 	/// Shutdown the event loop
 	Shutdown,
 	/// Register a new protocol handler.
@@ -74,16 +74,16 @@ pub enum IoMessage<Message> where Message: Send + Clone + Sized {
 		token: StreamToken,
 	},
 	/// Broadcast a message across all protocol handlers.
-	UserMessage(Message)
+	UserMessage(Arc<Message>)
 }
 
 /// IO access point. This is passed to all IO handlers and provides an interface to the IO subsystem.
-pub struct IoContext<Message> where Message: Send + Clone + Sync + 'static {
+pub struct IoContext<Message> where Message: Send + Sync + 'static {
 	channel: IoChannel<Message>,
 	handler: HandlerId,
 }
 
-impl<Message> IoContext<Message> where Message: Send + Clone + Sync + 'static {
+impl<Message> IoContext<Message> where Message: Send + Sync + 'static {
 	/// Create a new IO access point. Takes references to all the data that can be updated within the IO handler.
 	pub fn new(channel: IoChannel<Message>, handler: HandlerId) -> IoContext<Message> {
 		IoContext {
@@ -187,7 +187,7 @@ pub struct IoManager<Message> where Message: Send + Sync {
 	work_ready: Arc<SCondvar>,
 }
 
-impl<Message> IoManager<Message> where Message: Send + Sync + Clone + 'static {
+impl<Message> IoManager<Message> where Message: Send + Sync + 'static {
 	/// Creates a new instance and registers it with the event loop.
 	pub fn start(
 		event_loop: &mut EventLoop<IoManager<Message>>,
@@ -219,7 +219,7 @@ impl<Message> IoManager<Message> where Message: Send + Sync + Clone + 'static {
 	}
 }
 
-impl<Message> Handler for IoManager<Message> where Message: Send + Clone + Sync + 'static {
+impl<Message> Handler for IoManager<Message> where Message: Send + Sync + 'static {
 	type Timeout = Token;
 	type Message = IoMessage<Message>;
 
@@ -317,7 +317,12 @@ impl<Message> Handler for IoManager<Message> where Message: Send + Clone + Sync
 				for id in 0 .. MAX_HANDLERS {
 					if let Some(h) = self.handlers.read().get(id) {
 						let handler = h.clone();
-						self.worker_channel.push(Work { work_type: WorkType::Message(data.clone()), token: 0, handler: handler, handler_id: id });
+						self.worker_channel.push(Work {
+							work_type: WorkType::Message(data.clone()),
+							token: 0,
+							handler: handler,
+							handler_id: id
+						});
 					}
 				}
 				self.work_ready.notify_all();
@@ -326,21 +331,30 @@ impl<Message> Handler for IoManager<Message> where Message: Send + Clone + Sync
 	}
 }
 
-#[derive(Clone)]
+enum Handlers<Message> where Message: Send {
-enum Handlers<Message> where Message: Send + Clone {
 	SharedCollection(Weak<RwLock<Slab<Arc<IoHandler<Message>>, HandlerId>>>),
 	Single(Weak<IoHandler<Message>>),
 }
 
-/// Allows sending messages into the event loop. All the IO handlers will get the message
+impl<Message: Send> Clone for Handlers<Message> {
-/// in the `message` callback.
+	fn clone(&self) -> Self {
-pub struct IoChannel<Message> where Message: Send + Clone{
+		use self::Handlers::*;
-	channel: Option<Sender<IoMessage<Message>>>,
-	handlers: Handlers<Message>,
 
+		match *self {
+			SharedCollection(ref w) => SharedCollection(w.clone()),
+			Single(ref w) => Single(w.clone()),
+		}
+	}
 }
 
-impl<Message> Clone for IoChannel<Message> where Message: Send + Clone + Sync + 'static {
+/// Allows sending messages into the event loop. All the IO handlers will get the message
+/// in the `message` callback.
+pub struct IoChannel<Message> where Message: Send {
+	channel: Option<Sender<IoMessage<Message>>>,
+	handlers: Handlers<Message>,
+}
+
+impl<Message> Clone for IoChannel<Message> where Message: Send + Sync + 'static {
 	fn clone(&self) -> IoChannel<Message> {
 		IoChannel {
 			channel: self.channel.clone(),
@@ -349,11 +363,11 @@ impl<Message> Clone for IoChannel<Message> where Message: Send + Clone + Sync +
 	}
 }
 
-impl<Message> IoChannel<Message> where Message: Send + Clone + Sync + 'static {
+impl<Message> IoChannel<Message> where Message: Send + Sync + 'static {
 	/// Send a message through the channel
 	pub fn send(&self, message: Message) -> Result<(), IoError> {
 		match self.channel {
-			Some(ref channel) => channel.send(IoMessage::UserMessage(message))?,
+			Some(ref channel) => channel.send(IoMessage::UserMessage(Arc::new(message)))?,
 			None => self.send_sync(message)?
 		}
 		Ok(())
@@ -413,13 +427,13 @@ impl<Message> IoChannel<Message> where Message: Send + Clone + Sync + 'static {
 
 /// General IO Service. Starts an event loop and dispatches IO requests.
 /// 'Message' is a notification message type
-pub struct IoService<Message> where Message: Send + Sync + Clone + 'static {
+pub struct IoService<Message> where Message: Send + Sync + 'static {
 	thread: Mutex<Option<JoinHandle<()>>>,
 	host_channel: Mutex<Sender<IoMessage<Message>>>,
 	handlers: Arc<RwLock<Slab<Arc<IoHandler<Message>>, HandlerId>>>,
 }
 
-impl<Message> IoService<Message> where Message: Send + Sync + Clone + 'static {
+impl<Message> IoService<Message> where Message: Send + Sync + 'static {
 	/// Starts IO event loop
 	pub fn start() -> Result<IoService<Message>, IoError> {
 		let mut config = EventLoopBuilder::new();
@@ -462,7 +476,7 @@ impl<Message> IoService<Message> where Message: Send + Sync + Clone + 'static {
 
 	/// Send a message over the network. Normaly `HostIo::send` should be used. This can be used from non-io threads.
 	pub fn send_message(&self, message: Message) -> Result<(), IoError> {
-		self.host_channel.lock().send(IoMessage::UserMessage(message))?;
+		self.host_channel.lock().send(IoMessage::UserMessage(Arc::new(message)))?;
 		Ok(())
 	}
 
@@ -472,7 +486,7 @@ impl<Message> IoService<Message> where Message: Send + Sync + Clone + 'static {
 	}
 }
 
-impl<Message> Drop for IoService<Message> where Message: Send + Sync + Clone {
+impl<Message> Drop for IoService<Message> where Message: Send + Sync {
 	fn drop(&mut self) {
 		self.stop()
 	}

util/io/src/worker.rs

@@ -38,7 +38,7 @@ pub enum WorkType<Message> {
 	Writable,
 	Hup,
 	Timeout,
-	Message(Message)
+	Message(Arc<Message>)
 }
 
 pub struct Work<Message> {
@@ -65,7 +65,7 @@ impl Worker {
 						wait: Arc<SCondvar>,
 						wait_mutex: Arc<SMutex<()>>,
 					   ) -> Worker
-					where Message: Send + Sync + Clone + 'static {
+					where Message: Send + Sync + 'static {
 		let deleting = Arc::new(AtomicBool::new(false));
 		let mut worker = Worker {
 			thread: None,
@@ -86,7 +86,7 @@ impl Worker {
 						channel: IoChannel<Message>, wait: Arc<SCondvar>,
 						wait_mutex: Arc<SMutex<()>>,
 						deleting: Arc<AtomicBool>)
-						where Message: Send + Sync + Clone + 'static {
+						where Message: Send + Sync + 'static {
 		loop {
 			{
 				let lock = wait_mutex.lock().expect("Poisoned work_loop mutex");
@@ -105,7 +105,7 @@ impl Worker {
 		}
 	}
 
-	fn do_work<Message>(work: Work<Message>, channel: IoChannel<Message>) where Message: Send + Sync + Clone + 'static {
+	fn do_work<Message>(work: Work<Message>, channel: IoChannel<Message>) where Message: Send + Sync + 'static {
 		match work.work_type {
 			WorkType::Readable => {
 				work.handler.stream_readable(&IoContext::new(channel, work.handler_id), work.token);
@@ -120,7 +120,7 @@ impl Worker {
 				work.handler.timeout(&IoContext::new(channel, work.handler_id), work.token);
 			}
 			WorkType::Message(message) => {
-				work.handler.message(&IoContext::new(channel, work.handler_id), &message);
+				work.handler.message(&IoContext::new(channel, work.handler_id), &*message);
 			}
 		}
 	}