Merge branch 'master' into rpc

2016-01-25 13:09:46 +01:00
parent b835c5a338 692e5307e1
commit fede7ca35c
75 changed files with 1801 additions and 1154 deletions
--- a/src/account.rs
+++ b/src/account.rs
@@ -103,7 +103,7 @@ impl Account {
 	/// Get (and cache) the contents of the trie's storage at `key`.
 	pub fn storage_at(&self, db: &HashDB, key: &H256) -> H256 {
 		self.storage_overlay.borrow_mut().entry(key.clone()).or_insert_with(||{
-			(Filth::Clean, H256::from(SecTrieDB::new(db, &self.storage_root).get(key.bytes()).map(|v| -> U256 {decode(v)}).unwrap_or(U256::zero())))
+			(Filth::Clean, H256::from(SecTrieDB::new(db, &self.storage_root).get(key.bytes()).map_or(U256::zero(), |v| -> U256 {decode(v)})))
 		}).1.clone()
 	}

@@ -149,7 +149,7 @@ impl Account {
 	/// Provide a database to lookup `code_hash`. Should not be called if it is a contract without code.
 	pub fn cache_code(&mut self, db: &HashDB) -> bool {
 		// TODO: fill out self.code_cache;
-		return self.is_cached() ||
+		self.is_cached() ||
 			match self.code_hash {
 				Some(ref h) => match db.lookup(h) {
 					Some(x) => { self.code_cache = x.to_vec(); true },
@@ -248,8 +248,8 @@ mod tests {

 		let a = Account::from_rlp(&rlp);
 		assert_eq!(a.storage_root().unwrap().hex(), "c57e1afb758b07f8d2c8f13a3b6e44fa5ff94ab266facc5a4fd3f062426e50b2");
-		assert_eq!(a.storage_at(&mut db, &H256::from(&U256::from(0x00u64))), H256::from(&U256::from(0x1234u64)));
-		assert_eq!(a.storage_at(&mut db, &H256::from(&U256::from(0x01u64))), H256::new());
+		assert_eq!(a.storage_at(&db, &H256::from(&U256::from(0x00u64))), H256::from(&U256::from(0x1234u64)));
+		assert_eq!(a.storage_at(&db, &H256::from(&U256::from(0x01u64))), H256::new());
 	}

 	#[test]
--- a/src/account_diff.rs
+++ b/src/account_diff.rs
@@ -15,10 +15,10 @@ pub enum Existance {

 impl fmt::Display for Existance {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-		match self {
-			&Existance::Born => try!(write!(f, "+++")),
-			&Existance::Alive => try!(write!(f, "***")),
-			&Existance::Died => try!(write!(f, "XXX")),
+		match *self {
+			Existance::Born => try!(write!(f, "+++")),
+			Existance::Alive => try!(write!(f, "***")),
+			Existance::Died => try!(write!(f, "XXX")),
 		}
 		Ok(())
 	}
@@ -72,11 +72,11 @@ impl AccountDiff {
 					code: Diff::new(pre.code.clone(), post.code.clone()),
 					storage: storage.into_iter().map(|k|
 						(k.clone(), Diff::new(
-							pre.storage.get(&k).cloned().unwrap_or(H256::new()),
-							post.storage.get(&k).cloned().unwrap_or(H256::new())
+							pre.storage.get(&k).cloned().unwrap_or_else(H256::new),
+							post.storage.get(&k).cloned().unwrap_or_else(H256::new)
 						))).collect(),
 				};
-				if r.balance.is_same() && r.nonce.is_same() && r.code.is_same() && r.storage.len() == 0 {
+				if r.balance.is_same() && r.nonce.is_same() && r.code.is_same() && r.storage.is_empty() {
 					None
 				} else {
 					Some(r)
@@ -112,16 +112,15 @@ impl fmt::Display for AccountDiff {
 			Diff::Changed(ref pre, ref post) => try!(write!(f, "${} ({} {} {})", post, pre, if pre > post {"-"} else {"+"}, *max(pre, post) - *min(pre, post))),
 			_ => {},
 		}
-		match self.code {
-			Diff::Born(ref x) => try!(write!(f, "  code {}", x.pretty())),
-			_ => {},
+		if let Diff::Born(ref x) = self.code {
+			try!(write!(f, "  code {}", x.pretty()));
 		}
 		try!(write!(f, "\n"));
-		for (k, dv) in self.storage.iter() {
-			match dv {
-				&Diff::Born(ref v) => try!(write!(f, "    +  {} => {}\n", interpreted_hash(k), interpreted_hash(v))),
-				&Diff::Changed(ref pre, ref post) => try!(write!(f, "    *  {} => {} (was {})\n", interpreted_hash(k), interpreted_hash(post), interpreted_hash(pre))),
-				&Diff::Died(_) => try!(write!(f, "    X  {}\n", interpreted_hash(k))),
+		for (k, dv) in &self.storage {
+			match *dv {
+				Diff::Born(ref v) => try!(write!(f, "    +  {} => {}\n", interpreted_hash(k), interpreted_hash(v))),
+				Diff::Changed(ref pre, ref post) => try!(write!(f, "    *  {} => {} (was {})\n", interpreted_hash(k), interpreted_hash(post), interpreted_hash(pre))),
+				Diff::Died(_) => try!(write!(f, "    X  {}\n", interpreted_hash(k))),
 				_ => {},
 			}
 		}
--- a/src/bin/client/main.rs
+++ b/src/bin/client/main.rs
@@ -1,24 +1,49 @@
+#![feature(plugin)]
+// TODO: uncomment once this can be made to work.
+//#![plugin(docopt_macros)]
+
+extern crate docopt;
+extern crate rustc_serialize;
 extern crate ethcore_util as util;
 extern crate ethcore;
-extern crate rustc_serialize;
 extern crate log;
 extern crate env_logger;
+extern crate ctrlc;

 #[cfg(feature = "rpc")]
 mod rpc;

-use std::io::stdin;
 use std::env;
 use log::{LogLevelFilter};
 use env_logger::LogBuilder;
+use ctrlc::CtrlC;
 use util::*;
 use ethcore::client::*;
-use ethcore::service::ClientService;
+use ethcore::service::{ClientService, NetSyncMessage};
 use ethcore::ethereum;
 use ethcore::blockchain::CacheSize;
-use ethcore::sync::*;
+use ethcore::sync::EthSync;
+use docopt::Docopt;

-fn setup_log() {
+const USAGE: &'static str = "
+Parity. Ethereum Client.
+
+Usage:
+  parity [options]
+  parity [options] <enode>...
+
+Options:
+  -l --logging LOGGING  Specify the logging level
+  -h --help             Show this screen.
+";
+
+#[derive(Debug, RustcDecodable)]
+struct Args {
+    arg_enode: Option<Vec<String>>,
+    flag_logging: Option<String>,
+}
+
+fn setup_log(init: &Option<String>) {
 	let mut builder = LogBuilder::new();
 	builder.filter(None, LogLevelFilter::Info);

@@ -26,12 +51,16 @@ fn setup_log() {
 		builder.parse(&env::var("RUST_LOG").unwrap());
 	}

+	if let &Some(ref x) = init {
+		builder.parse(x);
+	}
+
 	builder.init().unwrap();
 }


 #[cfg(feature = "rpc")]
-fn setup_rpc_server(client: Arc<RwLock<Client>>) {
+fn setup_rpc_server(client: Arc<Client>) {
 	use self::rpc::*;
 	
 	let mut server = HttpServer::new(1);
@@ -43,49 +72,74 @@ fn setup_rpc_server(client: Arc<RwLock<Client>>) {
 }

 #[cfg(not(feature = "rpc"))]
-fn setup_rpc_server(_client: Arc<RwLock<Client>>) {
+fn setup_rpc_server(_client: Arc<Client>) {
 }

 fn main() {
-	setup_log();
+	let args: Args = Docopt::new(USAGE).and_then(|d| d.decode()).unwrap_or_else(|e| e.exit());
+
+	setup_log(&args.flag_logging);
+
 	let spec = ethereum::new_frontier();
-	let mut service = ClientService::start(spec).unwrap();
+	let init_nodes = match &args.arg_enode {
+		&None => spec.nodes().clone(),
+		&Some(ref enodes) => enodes.clone(),
+	};
+	let mut net_settings = NetworkConfiguration::new();
+	net_settings.boot_nodes = init_nodes;
+	let mut service = ClientService::start(spec, net_settings).unwrap();
 	setup_rpc_server(service.client());
-	let io_handler  = Box::new(ClientIoHandler { client: service.client(), timer: 0, info: Default::default() });
+	let io_handler  = Arc::new(ClientIoHandler { client: service.client(), info: Default::default(), sync: service.sync() });
 	service.io().register_handler(io_handler).expect("Error registering IO handler");
-	loop {
-		let mut cmd = String::new();
-		stdin().read_line(&mut cmd).unwrap();
-		if cmd == "quit\n" || cmd == "exit\n" || cmd == "q\n" {
-			break;
+
+	let exit = Arc::new(Condvar::new());
+	let e = exit.clone();
+	CtrlC::set_handler(move || { e.notify_all(); });
+	let mutex = Mutex::new(());
+	let _ = exit.wait(mutex.lock().unwrap()).unwrap();
+}
+
+struct Informant {
+	chain_info: RwLock<Option<BlockChainInfo>>,
+	cache_info: RwLock<Option<CacheSize>>,
+	report: RwLock<Option<ClientReport>>,
+}
+
+impl Default for Informant {
+	fn default() -> Self {
+		Informant {
+			chain_info: RwLock::new(None),
+			cache_info: RwLock::new(None),
+			report: RwLock::new(None),
 		}
 	}
 }

-#[derive(Default, Debug)]
-struct Informant {
-	chain_info: Option<BlockChainInfo>,
-	cache_info: Option<CacheSize>,
-	report: Option<ClientReport>,
-}
-
 impl Informant {
-	pub fn tick(&mut self, client: &Client) {
+	pub fn tick(&self, client: &Client, sync: &EthSync) {
 		// 5 seconds betwen calls. TODO: calculate this properly.
 		let dur = 5usize;

 		let chain_info = client.chain_info();
+		let queue_info = client.queue_info();
 		let cache_info = client.cache_info();
 		let report = client.report();
+		let sync_info = sync.status();

-		if let (_, &Some(ref last_cache_info), &Some(ref last_report)) = (&self.chain_info, &self.cache_info, &self.report) {
-			println!("[ {} {} ]---[ {} blk/s | {} tx/s | {} gas/s  //···{}···//  {} ({}) bl  {} ({}) ex ]",
+		if let (_, &Some(ref last_cache_info), &Some(ref last_report)) = (self.chain_info.read().unwrap().deref(), self.cache_info.read().unwrap().deref(), self.report.read().unwrap().deref()) {
+			println!("[ {} {} ]---[ {} blk/s | {} tx/s | {} gas/s  //··· {}/{} peers, {} downloaded, {}+{} queued ···//  {} ({}) bl  {} ({}) ex ]",
 				chain_info.best_block_number,
 				chain_info.best_block_hash,
 				(report.blocks_imported - last_report.blocks_imported) / dur,
 				(report.transactions_applied - last_report.transactions_applied) / dur,
 				(report.gas_processed - last_report.gas_processed) / From::from(dur),
-				0, // TODO: peers
+
+				sync_info.num_active_peers,
+				sync_info.num_peers,
+				sync_info.blocks_received,
+				queue_info.unverified_queue_size,
+				queue_info.verified_queue_size,
+
 				cache_info.blocks,
 				cache_info.blocks as isize - last_cache_info.blocks as isize,
 				cache_info.block_details,
@@ -93,28 +147,28 @@ impl Informant {
 			);
 		}

-		self.chain_info = Some(chain_info);
-		self.cache_info = Some(cache_info);
-		self.report = Some(report);
+		*self.chain_info.write().unwrap().deref_mut() = Some(chain_info);
+		*self.cache_info.write().unwrap().deref_mut() = Some(cache_info);
+		*self.report.write().unwrap().deref_mut() = Some(report);
 	}
 }

+const INFO_TIMER: TimerToken = 0;
+
 struct ClientIoHandler {
-	client: Arc<RwLock<Client>>,
-	timer: TimerToken,
+	client: Arc<Client>,
+	sync: Arc<EthSync>,
 	info: Informant,
 }

 impl IoHandler<NetSyncMessage> for ClientIoHandler {
-	fn initialize<'s>(&'s mut self, io: &mut IoContext<'s, NetSyncMessage>) { 
-		self.timer = io.register_timer(5000).expect("Error registering timer");
+	fn initialize(&self, io: &IoContext<NetSyncMessage>) { 
+		io.register_timer(INFO_TIMER, 5000).expect("Error registering timer");
 	}

-	fn timeout<'s>(&'s mut self, _io: &mut IoContext<'s, NetSyncMessage>, timer: TimerToken) {
-		if self.timer == timer {
-			let client = self.client.read().unwrap();
-			client.tick();
-			self.info.tick(client.deref());
+	fn timeout(&self, _io: &IoContext<NetSyncMessage>, timer: TimerToken) {
+		if INFO_TIMER == timer {
+			self.info.tick(&self.client, &self.sync);
 		}
 	}
 }
--- a/src/bin/client/rpc/impls/eth.rs
+++ b/src/bin/client/rpc/impls/eth.rs
@@ -6,11 +6,11 @@ use rpc::jsonrpc_core::*;
 use rpc::{Eth, EthFilter};

 pub struct EthClient {
-	client: Arc<RwLock<Client>>,
+	client: Arc<Client>,
 }

 impl EthClient {
-	pub fn new(client: Arc<RwLock<Client>>) -> Self {
+	pub fn new(client: Arc<Client>) -> Self {
 		EthClient {
 			client: client
 		}
@@ -41,7 +41,7 @@ impl Eth for EthClient {

 	fn block_number(&self, params: Params) -> Result<Value, Error> {
 		match params {
-			Params::None => Ok(Value::U64(self.client.read().unwrap().chain_info().best_block_number)),
+			Params::None => Ok(Value::U64(self.client.chain_info().best_block_number)),
 			_ => Err(Error::invalid_params())
 		}
 	}
@@ -62,11 +62,11 @@ impl Eth for EthClient {
 }

 pub struct EthFilterClient {
-	client: Arc<RwLock<Client>>
+	client: Arc<Client>
 }

 impl EthFilterClient {
-	pub fn new(client: Arc<RwLock<Client>>) -> Self {
+	pub fn new(client: Arc<Client>) -> Self {
 		EthFilterClient {
 			client: client
 		}
@@ -83,6 +83,6 @@ impl EthFilter for EthFilterClient {
 	}

 	fn filter_changes(&self, _: Params) -> Result<Value, Error> {
-		Ok(Value::String(self.client.read().unwrap().chain_info().best_block_hash.to_hex()))
+		Ok(Value::String(self.client.chain_info().best_block_hash.to_hex()))
 	}
 }
--- a/src/block.rs
+++ b/src/block.rs
@@ -1,3 +1,5 @@
+#![allow(ptr_arg)] // Because of &LastHashes -> &Vec<_>
+
 use common::*;
 use engine::*;
 use state::*;
@@ -173,7 +175,7 @@ impl<'x, 'y> OpenBlock<'x, 'y> {
 			timestamp: self.block.header.timestamp,
 			difficulty: self.block.header.difficulty.clone(),
 			last_hashes: self.last_hashes.clone(),		// TODO: should be a reference.
-			gas_used: self.block.archive.last().map(|t| t.receipt.gas_used).unwrap_or(U256::from(0)),
+			gas_used: self.block.archive.last().map_or(U256::zero(), |t| t.receipt.gas_used),
 			gas_limit: self.block.header.gas_limit.clone(),
 		}
 	}
@@ -204,7 +206,7 @@ impl<'x, 'y> OpenBlock<'x, 'y> {
 		s.block.header.state_root = s.block.state.root().clone();
 		s.block.header.receipts_root = ordered_trie_root(s.block.archive.iter().map(|ref e| e.receipt.rlp_bytes()).collect());
 		s.block.header.log_bloom = s.block.archive.iter().fold(LogBloom::zero(), |mut b, e| {b |= &e.receipt.log_bloom; b});
-		s.block.header.gas_used = s.block.archive.last().map(|t| t.receipt.gas_used).unwrap_or(U256::from(0));
+		s.block.header.gas_used = s.block.archive.last().map_or(U256::zero(), |t| t.receipt.gas_used);
 		s.block.header.note_dirty();

 		ClosedBlock::new(s, uncle_bytes)
@@ -255,7 +257,7 @@ impl SealedBlock {
 		let mut block_rlp = RlpStream::new_list(3);
 		self.block.header.stream_rlp(&mut block_rlp, Seal::With);
 		block_rlp.append_list(self.block.archive.len());
-		for e in self.block.archive.iter() { e.transaction.rlp_append(&mut block_rlp); }
+		for e in &self.block.archive { e.transaction.rlp_append(&mut block_rlp); }
 		block_rlp.append_raw(&self.uncle_bytes, 1);
 		block_rlp.out()
 	}
--- a/src/block_queue.rs
+++ b/src/block_queue.rs
@@ -1,12 +1,25 @@
+//! A queue of blocks. Sits between network or other I/O and the BlockChain.
+//! Sorts them ready for blockchain insertion.
 use std::thread::{JoinHandle, self};
 use std::sync::atomic::{AtomicBool, Ordering as AtomicOrdering};
 use util::*;
 use verification::*;
 use error::*;
 use engine::Engine;
-use sync::*;
 use views::*;
 use header::*;
+use service::*;
+
+/// Block queue status
+#[derive(Debug)]
+pub struct BlockQueueInfo {
+	/// Indicates that queue is full
+	pub full: bool,
+	/// Number of queued blocks pending verification
+	pub unverified_queue_size: usize,
+	/// Number of verified queued blocks pending import
+	pub verified_queue_size: usize,
+}

 /// A queue of blocks. Sits between network or other I/O and the BlockChain.
 /// Sorts them ready for blockchain insertion.
@@ -63,14 +76,15 @@ impl BlockQueue {
 		let deleting = Arc::new(AtomicBool::new(false));

 		let mut verifiers: Vec<JoinHandle<()>> = Vec::new();
-		let thread_count = max(::num_cpus::get(), 2) - 1;
-		for _ in 0..thread_count {
+		let thread_count = max(::num_cpus::get(), 3) - 2;
+		for i in 0..thread_count {
 			let verification = verification.clone();
 			let engine = engine.clone();
 			let more_to_verify = more_to_verify.clone();
 			let ready_signal = ready_signal.clone();
 			let deleting = deleting.clone();
-			verifiers.push(thread::spawn(move || BlockQueue::verify(verification, engine, more_to_verify, ready_signal,  deleting)));
+			verifiers.push(thread::Builder::new().name(format!("Verifier #{}", i)).spawn(move || BlockQueue::verify(verification, engine, more_to_verify, ready_signal,  deleting))
+				.expect("Error starting block verification thread"));
 		}
 		BlockQueue {
 			engine: engine,
@@ -204,7 +218,7 @@ impl BlockQueue {
 		verification.verified = new_verified;
 	}

-	/// TODO [arkpar] Please document me
+	/// Removes up to `max` verified blocks from the queue
 	pub fn drain(&mut self, max: usize) -> Vec<PreVerifiedBlock> {
 		let mut verification = self.verification.lock().unwrap();
 		let count = min(max, verification.verified.len());
@@ -215,8 +229,21 @@ impl BlockQueue {
 			result.push(block);
 		}
 		self.ready_signal.reset();
+		if !verification.verified.is_empty() {
+			self.ready_signal.set();
+		}
 		result
 	}
+
+	/// Get queue status.
+	pub fn queue_info(&self) -> BlockQueueInfo {
+		let verification = self.verification.lock().unwrap();
+		BlockQueueInfo {
+			full: false,
+			verified_queue_size: verification.verified.len(),
+			unverified_queue_size: verification.unverified.len(),
+		}
+	}
 }

 impl Drop for BlockQueue {
@@ -234,7 +261,7 @@ impl Drop for BlockQueue {
 mod tests {
 	use util::*;
 	use spec::*;
-	use queue::*;
+	use block_queue::*;

 	#[test]
 	fn test_block_queue() {
--- a/src/blockchain.rs
+++ b/src/blockchain.rs
@@ -153,9 +153,8 @@ impl BlockProvider for BlockChain {
 	fn block(&self, hash: &H256) -> Option<Bytes> {
 		{
 			let read = self.blocks.read().unwrap();
-			match read.get(hash) {
-				Some(v) => return Some(v.clone()),
-				None => ()
+			if let Some(v) = read.get(hash) {
+				return Some(v.clone());
 			}
 		}

@@ -188,7 +187,7 @@ impl BlockProvider for BlockChain {

 const COLLECTION_QUEUE_SIZE: usize = 2;
 const MIN_CACHE_SIZE: usize = 1;
-const MAX_CACHE_SIZE: usize = 1024 * 1024 * 1;
+const MAX_CACHE_SIZE: usize = 1024 * 1024;

 impl BlockChain {
 	/// Create new instance of blockchain from given Genesis
@@ -342,19 +341,19 @@ impl BlockChain {
 			Some(h) => h,
 			None => return None,
 		};
-		Some(self._tree_route((from_details, from), (to_details, to)))
+		Some(self._tree_route((&from_details, &from), (&to_details, &to)))
 	}

 	/// Similar to `tree_route` function, but can be used to return a route
 	/// between blocks which may not be in database yet.
-	fn _tree_route(&self, from: (BlockDetails, H256), to: (BlockDetails, H256)) -> TreeRoute {
+	fn _tree_route(&self, from: (&BlockDetails, &H256), to: (&BlockDetails, &H256)) -> TreeRoute {
 		let mut from_branch = vec![];
 		let mut to_branch = vec![];

-		let mut from_details = from.0;
-		let mut to_details = to.0;
-		let mut current_from = from.1;
-		let mut current_to = to.1;
+		let mut from_details = from.0.clone();
+		let mut to_details = to.0.clone();
+		let mut current_from = from.1.clone();
+		let mut current_to = to.1.clone();

 		// reset from && to to the same level
 		while from_details.number > to_details.number {
@@ -409,7 +408,7 @@ impl BlockChain {

 		// store block in db
 		self.blocks_db.put(&hash, &bytes).unwrap();
-		let (batch, new_best) = self.block_to_extras_insert_batch(bytes);
+		let (batch, new_best, details) = self.block_to_extras_insert_batch(bytes);

 		// update best block
 		let mut best_block = self.best_block.write().unwrap();
@@ -420,6 +419,8 @@ impl BlockChain {
 		// update caches
 		let mut write = self.block_details.write().unwrap();
 		write.remove(&header.parent_hash());
+		write.insert(hash.clone(), details);
+		self.note_used(CacheID::Block(hash));

 		// update extras database
 		self.extras_db.write(batch).unwrap();
@@ -427,7 +428,7 @@ impl BlockChain {

 	/// Transforms block into WriteBatch that may be written into database
 	/// Additionally, if it's new best block it returns new best block object.
-	fn block_to_extras_insert_batch(&self, bytes: &[u8]) -> (WriteBatch, Option<BestBlock>) {
+	fn block_to_extras_insert_batch(&self, bytes: &[u8]) -> (WriteBatch, Option<BestBlock>, BlockDetails) {
 		// create views onto rlp
 		let block = BlockView::new(bytes);
 		let header = block.header_view();
@@ -459,7 +460,7 @@ impl BlockChain {

 		// if it's not new best block, just return
 		if !is_new_best {
-			return (batch, None);
+			return (batch, None, details);
 		}

 		// if its new best block we need to make sure that all ancestors
@@ -467,7 +468,7 @@ impl BlockChain {
 		// find the route between old best block and the new one
 		let best_hash = self.best_block_hash();
 		let best_details = self.block_details(&best_hash).expect("best block hash is invalid!");
-		let route = self._tree_route((best_details, best_hash), (details, hash.clone()));
+		let route = self._tree_route((&best_details, &best_hash), (&details, &hash));

 		match route.blocks.len() {
 			// its our parent
@@ -494,7 +495,7 @@ impl BlockChain {
 			total_difficulty: total_difficulty
 		};

-		(batch, Some(best_block))
+		(batch, Some(best_block), details)
 	}

 	/// Returns true if transaction is known.
@@ -527,9 +528,8 @@ impl BlockChain {
 		K: ExtrasSliceConvertable + Eq + Hash + Clone {
 		{
 			let read = cache.read().unwrap();
-			match read.get(hash) {
-				Some(v) => return Some(v.clone()),
-				None => ()
+			if let Some(v) = read.get(hash) {
+				return Some(v.clone());
 			}
 		}

@@ -549,9 +549,8 @@ impl BlockChain {
 		T: ExtrasIndexable {
 		{
 			let read = cache.read().unwrap();
-			match read.get(hash) {
-				Some(_) => return true,
-				None => ()
+			if let Some(_) = read.get(hash) {
+				return true;
 			}
 		}

@@ -670,6 +669,7 @@ mod tests {
 	}

 	#[test]
+	#[allow(cyclomatic_complexity)]
 	fn test_small_fork() {
 		let genesis = "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".from_hex().unwrap();
 		let b1 = "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".from_hex().unwrap();
--- a/src/builtin.rs
+++ b/src/builtin.rs
@@ -94,16 +94,13 @@ pub fn new_builtin_exec(name: &str) -> Option<Box<Fn(&[u8], &mut [u8])>> {
 			if it.v == H256::from(&U256::from(27)) || it.v == H256::from(&U256::from(28)) {
 				let s = Signature::from_rsv(&it.r, &it.s, it.v[31] - 27);
 				if ec::is_valid(&s) {
-					match ec::recover(&s, &it.hash) {
-						Ok(p) => {
-							let r = p.as_slice().sha3();
-							// NICE: optimise and separate out into populate-like function
-							for i in 0..min(32, output.len()) {
-								output[i] = if i < 12 {0} else {r[i]};
-							}
+					if let Ok(p) = ec::recover(&s, &it.hash) {
+						let r = p.as_slice().sha3();
+						// NICE: optimise and separate out into populate-like function
+						for i in 0..min(32, output.len()) {
+							output[i] = if i < 12 {0} else {r[i]};
 						}
-						_ => {}
-					};
+					}
 				}
 			}
 		})),
--- a/src/client.rs
+++ b/src/client.rs
@@ -6,8 +6,8 @@ use error::*;
 use header::BlockNumber;
 use spec::Spec;
 use engine::Engine;
-use queue::BlockQueue;
-use sync::NetSyncMessage;
+use block_queue::{BlockQueue, BlockQueueInfo};
+use service::NetSyncMessage;
 use env_info::LastHashes;
 use verification::*;
 use block::*;
@@ -46,13 +46,6 @@ impl fmt::Display for BlockChainInfo {
 	}
 }

-/// Block queue status
-#[derive(Debug)]
-pub struct BlockQueueStatus {
-	/// TODO [arkpar] Please document me
-	pub full: bool,
-}
-
 /// TODO [arkpar] Please document me
 pub type TreeRoute = ::blockchain::TreeRoute;

@@ -95,13 +88,13 @@ pub trait BlockChainClient : Sync + Send {
 	fn block_receipts(&self, hash: &H256) -> Option<Bytes>;

 	/// Import a block into the blockchain.
-	fn import_block(&mut self, bytes: Bytes) -> ImportResult;
+	fn import_block(&self, bytes: Bytes) -> ImportResult;

 	/// Get block queue information.
-	fn queue_status(&self) -> BlockQueueStatus;
+	fn queue_info(&self) -> BlockQueueInfo;

 	/// Clear block queue and abort all import activity.
-	fn clear_queue(&mut self);
+	fn clear_queue(&self);

 	/// Get blockchain information.
 	fn chain_info(&self) -> BlockChainInfo;
@@ -132,19 +125,21 @@ pub struct Client {
 	chain: Arc<RwLock<BlockChain>>,
 	engine: Arc<Box<Engine>>,
 	state_db: JournalDB,
-	queue: BlockQueue,
-	report: ClientReport,
+	block_queue: RwLock<BlockQueue>,
+	report: RwLock<ClientReport>,
+	uncommited_states: RwLock<HashMap<H256, JournalDB>>,
+	import_lock: Mutex<()>
 }

 const HISTORY: u64 = 1000;

 impl Client {
 	/// Create a new client with given spec and DB path.
-	pub fn new(spec: Spec, path: &Path, message_channel: IoChannel<NetSyncMessage> ) -> Result<Client, Error> {
+	pub fn new(spec: Spec, path: &Path, message_channel: IoChannel<NetSyncMessage> ) -> Result<Arc<Client>, Error> {
 		let chain = Arc::new(RwLock::new(BlockChain::new(&spec.genesis_block(), path)));
 		let mut opts = Options::new();
-		opts.create_if_missing(true);
 		opts.set_max_open_files(256);
+		opts.create_if_missing(true);
 		/*opts.set_use_fsync(false);
 		opts.set_bytes_per_sync(8388608);
 		opts.set_disable_data_sync(false);
@@ -164,37 +159,36 @@ impl Client {

 		let mut state_path = path.to_path_buf();
 		state_path.push("state");
-		let db = DB::open(&opts, state_path.to_str().unwrap()).unwrap();
-		let mut state_db = JournalDB::new(db);
+		let db = Arc::new(DB::open(&opts, state_path.to_str().unwrap()).unwrap());
 		
 		let engine = Arc::new(try!(spec.to_engine()));
+		let mut state_db = JournalDB::new_with_arc(db.clone());
 		if engine.spec().ensure_db_good(&mut state_db) {
 			state_db.commit(0, &engine.spec().genesis_header().hash(), None).expect("Error commiting genesis state to state DB");
 		}
-
-//		chain.write().unwrap().ensure_good(&state_db);
-
-		Ok(Client {
+		Ok(Arc::new(Client {
 			chain: chain,
 			engine: engine.clone(),
 			state_db: state_db,
-			queue: BlockQueue::new(engine, message_channel),
-			report: Default::default(),
-		})
+			block_queue: RwLock::new(BlockQueue::new(engine, message_channel)),
+			report: RwLock::new(Default::default()),
+			uncommited_states: RwLock::new(HashMap::new()),
+			import_lock: Mutex::new(()),
+		}))
 	}

 	/// This is triggered by a message coming from a block queue when the block is ready for insertion
-	pub fn import_verified_blocks(&mut self) {
-		
+	pub fn import_verified_blocks(&self, _io: &IoChannel<NetSyncMessage>) {
 		let mut bad = HashSet::new();
-		let blocks = self.queue.drain(128); 
+		let _import_lock = self.import_lock.lock();
+		let blocks = self.block_queue.write().unwrap().drain(128); 
 		if blocks.is_empty() {
 			return;
 		}

 		for block in blocks {
 			if bad.contains(&block.header.parent_hash) {
-				self.queue.mark_as_bad(&block.header.hash());
+				self.block_queue.write().unwrap().mark_as_bad(&block.header.hash());
 				bad.insert(block.header.hash());
 				continue;
 			}
@@ -202,7 +196,7 @@ impl Client {
 			let header = &block.header;
 			if let Err(e) = verify_block_family(&header, &block.bytes, self.engine.deref().deref(), self.chain.read().unwrap().deref()) {
 				warn!(target: "client", "Stage 3 block verification failed for #{} ({})\nError: {:?}", header.number(), header.hash(), e);
-				self.queue.mark_as_bad(&header.hash());
+				self.block_queue.write().unwrap().mark_as_bad(&header.hash());
 				bad.insert(block.header.hash());
 				return;
 			};
@@ -210,7 +204,7 @@ impl Client {
 				Some(p) => p,
 				None => {
 					warn!(target: "client", "Block import failed for #{} ({}): Parent not found ({}) ", header.number(), header.hash(), header.parent_hash);
-					self.queue.mark_as_bad(&header.hash());
+					self.block_queue.write().unwrap().mark_as_bad(&header.hash());
 					bad.insert(block.header.hash());
 					return;
 				},
@@ -228,18 +222,19 @@ impl Client {
 				}
 			}

-			let result = match enact_verified(&block, self.engine.deref().deref(), self.state_db.clone(), &parent, &last_hashes) {
+			let db = self.state_db.clone();
+			let result = match enact_verified(&block, self.engine.deref().deref(), db, &parent, &last_hashes) {
 				Ok(b) => b,
 				Err(e) => {
 					warn!(target: "client", "Block import failed for #{} ({})\nError: {:?}", header.number(), header.hash(), e);
 				bad.insert(block.header.hash());
-					self.queue.mark_as_bad(&header.hash());
+					self.block_queue.write().unwrap().mark_as_bad(&header.hash());
 					return;
 				}
 			};
 			if let Err(e) = verify_block_final(&header, result.block().header()) {
 				warn!(target: "client", "Stage 4 block verification failed for #{} ({})\nError: {:?}", header.number(), header.hash(), e);
-				self.queue.mark_as_bad(&header.hash());
+				self.block_queue.write().unwrap().mark_as_bad(&header.hash());
 				return;
 			}

@@ -252,12 +247,16 @@ impl Client {
 					return;
 				}
 			}
-			self.report.accrue_block(&block);
-
+			self.report.write().unwrap().accrue_block(&block);
 			trace!(target: "client", "Imported #{} ({})", header.number(), header.hash());
 		}
 	}

+	/// Clear cached state overlay 
+	pub fn clear_state(&self, hash: &H256) {
+		self.uncommited_states.write().unwrap().remove(hash);
+	}
+
 	/// Get info on the cache.
 	pub fn cache_info(&self) -> CacheSize {
 		self.chain.read().unwrap().cache_size()
@@ -265,7 +264,7 @@ impl Client {

 	/// Get the report.
 	pub fn report(&self) -> ClientReport {
-		self.report.clone()
+		self.report.read().unwrap().clone()
 	}

 	/// Tick the client.
@@ -328,21 +327,20 @@ impl BlockChainClient for Client {
 		unimplemented!();
 	}

-	fn import_block(&mut self, bytes: Bytes) -> ImportResult {
+	fn import_block(&self, bytes: Bytes) -> ImportResult {
 		let header = BlockView::new(&bytes).header();
 		if self.chain.read().unwrap().is_known(&header.hash()) {
 			return Err(ImportError::AlreadyInChain);
 		}
-		self.queue.import_block(bytes)
+		self.block_queue.write().unwrap().import_block(bytes)
 	}

-	fn queue_status(&self) -> BlockQueueStatus {
-		BlockQueueStatus {
-			full: false
-		}
+	fn queue_info(&self) -> BlockQueueInfo {
+		self.block_queue.read().unwrap().queue_info()
 	}

-	fn clear_queue(&mut self) {
+	fn clear_queue(&self) {
+		self.block_queue.write().unwrap().clear();
 	}

 	fn chain_info(&self) -> BlockChainInfo {
--- a/src/env_info.rs
+++ b/src/env_info.rs
@@ -25,8 +25,14 @@ pub struct EnvInfo {
 }

 impl EnvInfo {
-	/// TODO [debris] Please document me
+	/// Create empty env_info initialized with zeros
 	pub fn new() -> EnvInfo {
+		EnvInfo::default()
+	}
+}
+
+impl Default for EnvInfo {
+	fn default() -> Self {
 		EnvInfo {
 			number: 0,
 			author: Address::new(),
@@ -53,11 +59,3 @@ impl FromJson for EnvInfo {
 		}
 	}
 }
-
-/// TODO: it should be the other way around.
-/// `new` should call `default`.
-impl Default for EnvInfo {
-	fn default() -> Self {
-		EnvInfo::new()
-	}
-}
--- a/src/ethereum/ethash.rs
+++ b/src/ethereum/ethash.rs
@@ -32,13 +32,13 @@ impl Ethash {
 	}

 	fn u64_param(&self, name: &str) -> u64 {
-		*self.u64_params.write().unwrap().entry(name.to_string()).or_insert_with(||
-			self.spec().engine_params.get(name).map(|a| decode(&a)).unwrap_or(0u64))
+		*self.u64_params.write().unwrap().entry(name.to_owned()).or_insert_with(||
+			self.spec().engine_params.get(name).map_or(0u64, |a| decode(&a)))
 	}

 	fn u256_param(&self, name: &str) -> U256 {
-		*self.u256_params.write().unwrap().entry(name.to_string()).or_insert_with(||
-			self.spec().engine_params.get(name).map(|a| decode(&a)).unwrap_or(x!(0)))
+		*self.u256_params.write().unwrap().entry(name.to_owned()).or_insert_with(||
+			self.spec().engine_params.get(name).map_or(x!(0), |a| decode(&a)))
 	}
 }

@@ -84,7 +84,7 @@ impl Engine for Ethash {
 	/// 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 Block) {
-		let reward = self.spec().engine_params.get("blockReward").map(|a| decode(&a)).unwrap_or(U256::from(0u64));
+		let reward = self.spec().engine_params.get("blockReward").map_or(U256::from(0u64), |a| decode(&a));
 		let fields = block.fields();

 		// Bestow block reward
@@ -153,6 +153,7 @@ impl Engine for Ethash {
 	}
 }

+#[allow(wrong_self_convention)] // to_ethash should take self
 impl Ethash {
 	fn calculate_difficuty(&self, header: &Header, parent: &Header) -> U256 {
 		const EXP_DIFF_PERIOD: u64 = 100000;
--- a/src/evm/factory.rs
+++ b/src/evm/factory.rs
@@ -68,10 +68,11 @@ impl Factory {
 	fn jit() -> Box<Evm> {
 		unimplemented!()
 	}
-
+}
+impl Default for Factory {
 	/// Returns jitvm factory
 	#[cfg(feature = "jit")]
-	pub fn default() -> Factory {
+	fn default() -> Factory {
 		Factory {
 			evm: VMType::Jit
 		}
@@ -79,7 +80,7 @@ impl Factory {

 	/// Returns native rust evm factory
 	#[cfg(not(feature = "jit"))]
-	pub fn default() -> Factory {
+	fn default() -> Factory {
 		Factory {
 			evm: VMType::Interpreter
 		}
--- a/src/evm/interpreter.rs
+++ b/src/evm/interpreter.rs
@@ -7,19 +7,19 @@ use super::instructions::Instruction;
 use std::marker::Copy;
 use evm::{MessageCallResult, ContractCreateResult};

-#[cfg(not(feature = "evm_debug"))]
+#[cfg(not(feature = "evm-debug"))]
 macro_rules! evm_debug {
 	($x: expr) => {}
 }

-#[cfg(feature = "evm_debug")]
+#[cfg(feature = "evm-debug")]
 macro_rules! evm_debug {
 	($x: expr) => {
 		$x
 	}
 }

-#[cfg(feature = "evm_debug")]
+#[cfg(feature = "evm-debug")]
 fn color(instruction: Instruction, name: &'static str) -> String {
 	let c = instruction as usize % 6;
 	let colors = [31, 34, 33, 32, 35, 36];
@@ -72,7 +72,7 @@ impl<S : Copy> VecStack<S> {

 impl<S : fmt::Display> Stack<S> for VecStack<S> {
 	fn peek(&self, no_from_top: usize) -> &S {
-		return &self.stack[self.stack.len() - no_from_top - 1];
+		&self.stack[self.stack.len() - no_from_top - 1]
 	}

 	fn swap_with_top(&mut self, no_from_top: usize) {
@@ -157,7 +157,7 @@ impl Memory for Vec<u8> {
 	}

 	fn size(&self) -> usize {
-		return self.len()
+		self.len()
 	}

 	fn read_slice(&self, init_off_u: U256, init_size_u: U256) -> &[u8] {
@@ -228,6 +228,7 @@ struct CodeReader<'a> {
 	code: &'a Bytes
 }

+#[allow(len_without_is_empty)]
 impl<'a> CodeReader<'a> {
 	/// Get `no_of_bytes` from code and convert to U256. Move PC
 	fn read(&mut self, no_of_bytes: usize) -> U256 {
@@ -330,6 +331,7 @@ impl evm::Evm for Interpreter {
 }

 impl Interpreter {
+	#[allow(cyclomatic_complexity)]
 	fn get_gas_cost_mem(&self,
 						ext: &evm::Ext,
 						instruction: Instruction,
@@ -716,7 +718,7 @@ impl Interpreter {
 				let big_id = stack.pop_back();
 				let id = big_id.low_u64() as usize;
 				let max = id.wrapping_add(32);
-				let data = params.data.clone().unwrap_or(vec![]);
+				let data = params.data.clone().unwrap_or_else(|| vec![]);
 				let bound = cmp::min(data.len(), max);
 				if id < bound && big_id < U256::from(data.len()) {
 					let mut v = data[id..bound].to_vec();
@@ -727,7 +729,7 @@ impl Interpreter {
 				}
 			},
 			instructions::CALLDATASIZE => {
-				stack.push(U256::from(params.data.clone().unwrap_or(vec![]).len()));
+				stack.push(U256::from(params.data.clone().map_or(0, |l| l.len())));
 			},
 			instructions::CODESIZE => {
 				stack.push(U256::from(code.len()));
@@ -738,10 +740,10 @@ impl Interpreter {
 				stack.push(U256::from(len));
 			},
 			instructions::CALLDATACOPY => {
-				self.copy_data_to_memory(mem, stack, &params.data.clone().unwrap_or(vec![]));
+				self.copy_data_to_memory(mem, stack, &params.data.clone().unwrap_or_else(|| vec![]));
 			},
 			instructions::CODECOPY => {
-				self.copy_data_to_memory(mem, stack, &params.code.clone().unwrap_or(vec![]));
+				self.copy_data_to_memory(mem, stack, &params.code.clone().unwrap_or_else(|| vec![]));
 			},
 			instructions::EXTCODECOPY => {
 				let address = u256_to_address(&stack.pop_back());
@@ -781,7 +783,7 @@ impl Interpreter {
 	fn copy_data_to_memory(&self,
 						   mem: &mut Memory,
 						   stack: &mut Stack<U256>,
-						   data: &Bytes) {
+						   data: &[u8]) {
 		let offset = stack.pop_back();
 		let index = stack.pop_back();
 		let size = stack.pop_back();
@@ -1051,7 +1053,7 @@ impl Interpreter {
 		Ok(())
 	}

-	fn find_jump_destinations(&self, code: &Bytes) -> HashSet<CodePosition> {
+	fn find_jump_destinations(&self, code: &[u8]) -> HashSet<CodePosition> {
 		let mut jump_dests = HashSet::new();
 		let mut position = 0;

@@ -1066,7 +1068,7 @@ impl Interpreter {
 			position += 1;
 		}

-		return jump_dests;
+		jump_dests
 	}
 }

--- a/src/evm/tests.rs
+++ b/src/evm/tests.rs
@@ -19,7 +19,7 @@ struct FakeExt {
 	logs: Vec<FakeLogEntry>,
 	_suicides: HashSet<Address>,
 	info: EnvInfo,
-	_schedule: Schedule
+	schedule: Schedule
 }

 impl FakeExt {
@@ -89,7 +89,7 @@ impl Ext for FakeExt {
 	}

 	fn schedule(&self) -> &Schedule {
-		&self._schedule
+		&self.schedule
 	}

 	fn env_info(&self) -> &EnvInfo {
@@ -122,7 +122,7 @@ fn test_stack_underflow() {
 	};
 	
 	match err {
-		evm::Error::StackUnderflow {instruction: _, wanted, on_stack} => {
+		evm::Error::StackUnderflow {wanted, on_stack, ..} => {
 			assert_eq!(wanted, 2);
 			assert_eq!(on_stack, 0);
 		}
--- a/src/executive.rs
+++ b/src/executive.rs
@@ -75,7 +75,7 @@ impl<'a> Executive<'a> {
 	}

 	/// Creates `Externalities` from `Executive`.
-	pub fn to_externalities<'_>(&'_ mut self, origin_info: OriginInfo, substate: &'_ mut Substate, output: OutputPolicy<'_>) -> Externalities {
+	pub fn as_externalities<'_>(&'_ mut self, origin_info: OriginInfo, substate: &'_ mut Substate, output: OutputPolicy<'_>) -> Externalities {
 		Externalities::new(self.state, self.info, self.engine, self.depth, origin_info, substate, output)
 	}

@@ -123,8 +123,8 @@ impl<'a> Executive<'a> {

 		let mut substate = Substate::new();

-		let res = match t.action() {
-			&Action::Create => {
+		let res = match *t.action() {
+			Action::Create => {
 				let new_address = contract_address(&sender, &nonce);
 				let params = ActionParams {
 					code_address: new_address.clone(),
@@ -139,7 +139,7 @@ impl<'a> Executive<'a> {
 				};
 				self.create(params, &mut substate)
 			},
-			&Action::Call(ref address) => {
+			Action::Call(ref address) => {
 				let params = ActionParams {
 					code_address: address.clone(),
 					address: address.clone(),
@@ -177,7 +177,7 @@ impl<'a> Executive<'a> {
 			// if destination is builtin, try to execute it
 			
 			let default = [];
-			let data = if let &Some(ref d) = &params.data { d as &[u8] } else { &default as &[u8] };
+			let data = if let Some(ref d) = params.data { d as &[u8] } else { &default as &[u8] };

 			let cost = self.engine.cost_of_builtin(&params.code_address, data);
 			match cost <= params.gas {
@@ -198,7 +198,7 @@ impl<'a> Executive<'a> {
 			let mut unconfirmed_substate = Substate::new();

 			let res = {
-				let mut ext = self.to_externalities(OriginInfo::from(&params), &mut unconfirmed_substate, OutputPolicy::Return(output));
+				let mut ext = self.as_externalities(OriginInfo::from(&params), &mut unconfirmed_substate, OutputPolicy::Return(output));
 				self.engine.vm_factory().create().exec(params, &mut ext)
 			};

@@ -230,7 +230,7 @@ impl<'a> Executive<'a> {
 		self.state.transfer_balance(&params.sender, &params.address, &params.value);

 		let res = {
-			let mut ext = self.to_externalities(OriginInfo::from(&params), &mut unconfirmed_substate, OutputPolicy::InitContract);
+			let mut ext = self.as_externalities(OriginInfo::from(&params), &mut unconfirmed_substate, OutputPolicy::InitContract);
 			self.engine.vm_factory().create().exec(params, &mut ext)
 		};
 		self.enact_result(&res, substate, unconfirmed_substate, backup);
@@ -248,7 +248,7 @@ impl<'a> Executive<'a> {
 		let refunds_bound = sstore_refunds + suicide_refunds;

 		// real ammount to refund
-		let gas_left_prerefund = match &result { &Ok(x) => x, _ => x!(0) };
+		let gas_left_prerefund = match result { Ok(x) => x, _ => x!(0) };
 		let refunded = cmp::min(refunds_bound, (t.gas - gas_left_prerefund) / U256::from(2));
 		let gas_left = gas_left_prerefund + refunded;

@@ -265,7 +265,7 @@ impl<'a> Executive<'a> {
 		self.state.add_balance(&self.info.author, &fees_value);

 		// perform suicides
-		for address in substate.suicides.iter() {
+		for address in &substate.suicides {
 			trace!("Killing {}", address);
 			self.state.kill_account(address);
 		}
@@ -273,11 +273,7 @@ impl<'a> Executive<'a> {
 		match result { 
 			Err(evm::Error::Internal) => Err(ExecutionError::Internal),
 			// TODO [ToDr] BadJumpDestination @debris - how to handle that?
-			Err(evm::Error::OutOfGas) 
-				| Err(evm::Error::BadJumpDestination { destination: _ }) 
-				| Err(evm::Error::BadInstruction { instruction: _ }) 
-				| Err(evm::Error::StackUnderflow {instruction: _, wanted: _, on_stack: _})
-				| Err(evm::Error::OutOfStack {instruction: _, wanted: _, limit: _}) => {
+			Err(_) => {
 				Ok(Executed {
 					gas: t.gas,
 					gas_used: t.gas,
@@ -302,15 +298,15 @@ impl<'a> Executive<'a> {

 	fn enact_result(&mut self, result: &evm::Result, substate: &mut Substate, un_substate: Substate, backup: State) {
 		// TODO: handle other evm::Errors same as OutOfGas once they are implemented
-		match result {
-			&Err(evm::Error::OutOfGas)
-				| &Err(evm::Error::BadJumpDestination { destination: _ }) 
-				| &Err(evm::Error::BadInstruction { instruction: _ }) 
-				| &Err(evm::Error::StackUnderflow {instruction: _, wanted: _, on_stack: _})
-				| &Err(evm::Error::OutOfStack {instruction: _, wanted: _, limit: _}) => {
+		match *result {
+			Err(evm::Error::OutOfGas)
+				| Err(evm::Error::BadJumpDestination {..}) 
+				| Err(evm::Error::BadInstruction {.. }) 
+				| Err(evm::Error::StackUnderflow {..})
+				| Err(evm::Error::OutOfStack {..}) => {
 				self.state.revert(backup);
 			},
-			&Ok(_) | &Err(evm::Error::Internal) => substate.accrue(un_substate)
+			Ok(_) | Err(evm::Error::Internal) => substate.accrue(un_substate)
 		}
 	}
 }
--- a/src/externalities.rs
+++ b/src/externalities.rs
@@ -158,9 +158,10 @@ impl<'a> Ext for Externalities<'a> {
 	}

 	fn extcode(&self, address: &Address) -> Bytes {
-		self.state.code(address).unwrap_or(vec![])
+		self.state.code(address).unwrap_or_else(|| vec![])
 	}

+	#[allow(match_ref_pats)]
 	fn ret(&mut self, gas: &U256, data: &[u8]) -> Result<U256, evm::Error> {
 		match &mut self.output {
 			&mut OutputPolicy::Return(BytesRef::Fixed(ref mut slice)) => unsafe {
--- a/src/header.rs
+++ b/src/header.rs
@@ -2,7 +2,7 @@ use util::*;
 use basic_types::*;
 use time::now_utc;

-/// TODO [Gav Wood] Please document me
+/// Type for Block number
 pub type BlockNumber = u64;

 /// A block header.
@@ -171,9 +171,10 @@ impl Header {
 		s.append(&self.gas_used);
 		s.append(&self.timestamp);
 		s.append(&self.extra_data);
-		match with_seal {
-			Seal::With => for b in self.seal.iter() { s.append_raw(&b, 1); },
-			_ => {}
+		if let Seal::With = with_seal {
+			for b in &self.seal { 
+				s.append_raw(&b, 1); 
+			}
 		}
 	}

@@ -236,7 +237,7 @@ impl Encodable for Header {
 			self.timestamp.encode(e);
 			self.extra_data.encode(e);

-			for b in self.seal.iter() {
+			for b in &self.seal {
 				e.emit_raw(&b);
 			}
 		})
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,8 +1,11 @@
 #![warn(missing_docs)]
 #![feature(cell_extras)]
 #![feature(augmented_assignments)]
-//#![feature(plugin)]
+#![feature(plugin)]
 //#![plugin(interpolate_idents)]
+#![plugin(clippy)]
+#![allow(needless_range_loop, match_bool)]
+
 //! Ethcore's ethereum implementation
 //!
 //! ### Rust version
@@ -73,7 +76,6 @@
 //!       sudo make install
 //!       sudo ldconfig
 //!       ```
-
 #[macro_use]
 extern crate log;
 extern crate rustc_serialize;
@@ -89,6 +91,8 @@ extern crate evmjit;
 #[macro_use]
 extern crate ethcore_util as util;

+// NOTE: Add doc parser exception for these pub declarations.
+
 /// TODO [Gav Wood] Please document me
 pub mod common;
 /// TODO [Tomusdrw] Please document me
@@ -149,6 +153,5 @@ pub mod sync;
 pub mod block;
 /// TODO [arkpar] Please document me
 pub mod verification;
-/// TODO [debris] Please document me
-pub mod queue;
+pub mod block_queue;
 pub mod ethereum;
--- a/src/null_engine.rs
+++ b/src/null_engine.rs
@@ -11,7 +11,7 @@ pub struct NullEngine {
 }

 impl NullEngine {
-	/// TODO [Tomusdrw] Please document me
+	/// Returns new instance of NullEngine with default VM Factory
 	pub fn new_boxed(spec: Spec) -> Box<Engine> {
 		Box::new(NullEngine{
 			spec: spec,
--- a/src/pod_state.rs
+++ b/src/pod_state.rs
@@ -26,10 +26,10 @@ impl FromJson for PodState {
 			let code = acc.find("code").map(&Bytes::from_json);
 			if balance.is_some() || nonce.is_some() || storage.is_some() || code.is_some() {
 				state.insert(address_from_hex(address), PodAccount{
-					balance: balance.unwrap_or(U256::zero()),
-					nonce: nonce.unwrap_or(U256::zero()),
-					storage: storage.unwrap_or(BTreeMap::new()),
-					code: code.unwrap_or(Vec::new())
+					balance: balance.unwrap_or_else(U256::zero),
+					nonce: nonce.unwrap_or_else(U256::zero),
+					storage: storage.unwrap_or_else(BTreeMap::new),
+					code: code.unwrap_or_else(Vec::new)
 				});
 			}
 			state
--- a/src/receipt.rs
+++ b/src/receipt.rs
@@ -36,7 +36,7 @@ impl RlpStandard for Receipt {
 		// TODO: make work:
 		//s.append(&self.logs);
 		s.append_list(self.logs.len());
-		for l in self.logs.iter() {
+		for l in &self.logs {
 			l.rlp_append(s);
 		}
 	}
--- a/src/service.rs
+++ b/src/service.rs
@@ -5,24 +5,37 @@ use error::*;
 use std::env;
 use client::Client;

+/// Message type for external and internal events
+#[derive(Clone)]
+pub enum SyncMessage {
+	/// New block has been imported into the blockchain
+	NewChainBlock(Bytes), //TODO: use Cow
+	/// A block is ready 
+	BlockVerified,
+}
+
+/// TODO [arkpar] Please document me
+pub type NetSyncMessage = NetworkIoMessage<SyncMessage>;
+
 /// Client service setup. Creates and registers client and network services with the IO subsystem.
 pub struct ClientService {
 	net_service: NetworkService<SyncMessage>,
-	client: Arc<RwLock<Client>>,
+	client: Arc<Client>,
+	sync: Arc<EthSync>,
 }

 impl ClientService {
 	/// Start the service in a separate thread.
-	pub fn start(spec: Spec) -> Result<ClientService, Error> {
-		let mut net_service = try!(NetworkService::start());
+	pub fn start(spec: Spec, net_config: NetworkConfiguration) -> Result<ClientService, Error> {
+		let mut net_service = try!(NetworkService::start(net_config));
 		info!("Starting {}", net_service.host_info());
 		info!("Configured for {} using {} engine", spec.name, spec.engine_name);
 		let mut dir = env::home_dir().unwrap();
 		dir.push(".parity");
 		dir.push(H64::from(spec.genesis_header().hash()).hex());
-		let client = Arc::new(RwLock::new(try!(Client::new(spec, &dir, net_service.io().channel()))));
-		EthSync::register(&mut net_service, client.clone());
-		let client_io = Box::new(ClientIoHandler {
+		let client = try!(Client::new(spec, &dir, net_service.io().channel()));
+		let sync = EthSync::register(&mut net_service, client.clone());
+		let client_io = Arc::new(ClientIoHandler {
 			client: client.clone()
 		});
 		try!(net_service.io().register_handler(client_io));
@@ -30,43 +43,62 @@ impl ClientService {
 		Ok(ClientService {
 			net_service: net_service,
 			client: client,
+			sync: sync,
 		})
 	}

+	/// Get the network service.
+	pub fn add_node(&mut self, _enode: &str) {
+		unimplemented!();
+	}
+
 	/// TODO [arkpar] Please document me
 	pub fn io(&mut self) -> &mut IoService<NetSyncMessage> {
 		self.net_service.io()
 	}

 	/// TODO [arkpar] Please document me
-	pub fn client(&self) -> Arc<RwLock<Client>> {
+	pub fn client(&self) -> Arc<Client> {
 		self.client.clone()
+	
+	}
+	
+	/// Get shared sync handler
+	pub fn sync(&self) -> Arc<EthSync> {
+		self.sync.clone()
 	}
 }

 /// IO interface for the Client handler
 struct ClientIoHandler {
-	client: Arc<RwLock<Client>>
+	client: Arc<Client>
 }

+const CLIENT_TICK_TIMER: TimerToken = 0;
+const CLIENT_TICK_MS: u64 = 5000;
+
 impl IoHandler<NetSyncMessage> for ClientIoHandler {
-	fn initialize<'s>(&'s mut self, _io: &mut IoContext<'s, NetSyncMessage>) {
+	fn initialize(&self, io: &IoContext<NetSyncMessage>) {
+		io.register_timer(CLIENT_TICK_TIMER, CLIENT_TICK_MS).expect("Error registering client timer");
 	}

-	fn message<'s>(&'s mut self, _io: &mut IoContext<'s, NetSyncMessage>, net_message: &'s mut NetSyncMessage) {
-		match net_message {
-			&mut UserMessage(ref mut message) =>  {
-				match message {
-					&mut SyncMessage::BlockVerified => {
-						self.client.write().unwrap().import_verified_blocks();
-					},
-					_ => {}, // ignore other messages
-				}
-
-			}
-			_ => {}, // ignore other messages
+	fn timeout(&self, _io: &IoContext<NetSyncMessage>, timer: TimerToken) {
+		if timer == CLIENT_TICK_TIMER {
+			self.client.tick();
 		}
+	}

+	#[allow(match_ref_pats)]
+	#[allow(single_match)]
+	fn message(&self, io: &IoContext<NetSyncMessage>, net_message: &NetSyncMessage) {
+		if let &UserMessage(ref message) = net_message {
+			match message {
+				&SyncMessage::BlockVerified => {
+					self.client.import_verified_blocks(&io.channel());
+				},
+				_ => {}, // ignore other messages
+			}
+		}
 	}
 }

--- a/src/spec.rs
+++ b/src/spec.rs
@@ -10,7 +10,7 @@ pub fn gzip64res_to_json(source: &[u8]) -> Json {
 	let data = source.from_base64().expect("Genesis block is malformed!");
 	let data_ref: &[u8] = &data;
 	let mut decoder = GzDecoder::new(data_ref).expect("Gzip is invalid");
-	let mut s: String = "".to_string();
+	let mut s: String = "".to_owned();
 	decoder.read_to_string(&mut s).expect("Gzip is invalid");
 	Json::from_str(&s).expect("Json is invalid")
 }
@@ -18,14 +18,14 @@ pub fn gzip64res_to_json(source: &[u8]) -> Json {
 /// Convert JSON value to equivlaent RLP representation.
 // TODO: handle container types.
 fn json_to_rlp(json: &Json) -> Bytes {
-	match json {
-		&Json::Boolean(o) => encode(&(if o {1u64} else {0})),
-		&Json::I64(o) => encode(&(o as u64)),
-		&Json::U64(o) => encode(&o),
-		&Json::String(ref s) if s.len() >= 2 && &s[0..2] == "0x" && U256::from_str(&s[2..]).is_ok() => {
+	match *json {
+		Json::Boolean(o) => encode(&(if o {1u64} else {0})),
+		Json::I64(o) => encode(&(o as u64)),
+		Json::U64(o) => encode(&o),
+		Json::String(ref s) if s.len() >= 2 && &s[0..2] == "0x" && U256::from_str(&s[2..]).is_ok() => {
 			encode(&U256::from_str(&s[2..]).unwrap())
 		},
-		&Json::String(ref s) => {
+		Json::String(ref s) => {
 			encode(s)
 		},
 		_ => panic!()
@@ -73,6 +73,9 @@ pub struct Spec {
 	/// TODO [Gav Wood] Please document me
 	pub engine_name: String,

+	/// Known nodes on the network in enode format.
+	pub nodes: Vec<String>,
+
 	// Parameters concerning operation of the specific engine we're using.
 	// Name -> RLP-encoded value
 	/// TODO [Gav Wood] Please document me
@@ -108,6 +111,7 @@ pub struct Spec {
 	state_root_memo: RwLock<Option<H256>>,
 }

+#[allow(wrong_self_convention)] // because to_engine(self) should be to_engine(&self)
 impl Spec {
 	/// Convert this object into a boxed Engine of the right underlying type.
 	// TODO avoid this hard-coded nastiness - use dynamic-linked plugin framework instead.
@@ -127,6 +131,9 @@ impl Spec {
 		self.state_root_memo.read().unwrap().as_ref().unwrap().clone()
 	}

+	/// Get the known knodes of the network in enode format.
+	pub fn nodes(&self) -> &Vec<String> { &self.nodes }
+
 	/// TODO [Gav Wood] Please document me
 	pub fn genesis_header(&self) -> Header {
 		Header {
@@ -185,17 +192,21 @@ impl FromJson for Spec {
 						builtins.insert(addr.clone(), builtin);
 					}
 				}
-				let balance = acc.find("balance").and_then(|x| match x { &Json::String(ref b) => U256::from_dec_str(b).ok(), _ => None });
-				let nonce = acc.find("nonce").and_then(|x| match x { &Json::String(ref b) => U256::from_dec_str(b).ok(), _ => None });
+				let balance = acc.find("balance").and_then(|x| match *x { Json::String(ref b) => U256::from_dec_str(b).ok(), _ => None });
+				let nonce = acc.find("nonce").and_then(|x| match *x { Json::String(ref b) => U256::from_dec_str(b).ok(), _ => None });
 //				let balance = if let Some(&Json::String(ref b)) = acc.find("balance") {U256::from_dec_str(b).unwrap_or(U256::from(0))} else {U256::from(0)};
 //				let nonce = if let Some(&Json::String(ref n)) = acc.find("nonce") {U256::from_dec_str(n).unwrap_or(U256::from(0))} else {U256::from(0)};
 				// TODO: handle code & data if they exist.
 				if balance.is_some() || nonce.is_some() {
-					state.insert(addr, GenesisAccount { balance: balance.unwrap_or(U256::from(0)), nonce: nonce.unwrap_or(U256::from(0)) });
+					state.insert(addr, GenesisAccount { balance: balance.unwrap_or_else(U256::zero), nonce: nonce.unwrap_or_else(U256::zero) });
 				}
 			}
 		}

+		let nodes = if let Some(&Json::Array(ref ns)) = json.find("nodes") {
+			ns.iter().filter_map(|n| if let Json::String(ref s) = *n { Some(s.clone()) } else {None}).collect()
+		} else { Vec::new() };
+
 		let genesis = &json["genesis"];//.as_object().expect("No genesis object in JSON");

 		let (seal_fields, seal_rlp) = {
@@ -212,12 +223,12 @@ impl FromJson for Spec {
 				)
 			}
 		};
-
 		
 		Spec {
-			name: json.find("name").map(|j| j.as_string().unwrap()).unwrap_or("unknown").to_string(),
-			engine_name: json["engineName"].as_string().unwrap().to_string(),
+			name: json.find("name").map_or("unknown", |j| j.as_string().unwrap()).to_owned(),
+			engine_name: json["engineName"].as_string().unwrap().to_owned(),
 			engine_params: json_to_rlp_map(&json["params"]),
+			nodes: nodes,
 			builtins: builtins,
 			parent_hash: H256::from_str(&genesis["parentHash"].as_string().unwrap()[2..]).unwrap(),
 			author: Address::from_str(&genesis["author"].as_string().unwrap()[2..]).unwrap(),
@@ -242,7 +253,7 @@ impl Spec {
 			let mut root = H256::new(); 
 			{
 				let mut t = SecTrieDBMut::new(db, &mut root);
-				for (address, account) in self.genesis_state.iter() {
+				for (address, account) in &self.genesis_state {
 					t.insert(address.as_slice(), &account.rlp());
 				}
 			}
--- a/src/state.rs
+++ b/src/state.rs
@@ -88,22 +88,22 @@ impl State {

 	/// Get the balance of account `a`.
 	pub fn balance(&self, a: &Address) -> U256 {
-		self.get(a, false).as_ref().map(|account| account.balance().clone()).unwrap_or(U256::from(0u8))
+		self.get(a, false).as_ref().map_or(U256::zero(), |account| account.balance().clone())
 	}

 	/// Get the nonce of account `a`.
 	pub fn nonce(&self, a: &Address) -> U256 {
-		self.get(a, false).as_ref().map(|account| account.nonce().clone()).unwrap_or(U256::from(0u8))
+		self.get(a, false).as_ref().map_or(U256::zero(), |account| account.nonce().clone())
 	}

 	/// Mutate storage of account `a` so that it is `value` for `key`.
 	pub fn storage_at(&self, a: &Address, key: &H256) -> H256 {
-		self.get(a, false).as_ref().map(|a|a.storage_at(&self.db, key)).unwrap_or(H256::new())	
+		self.get(a, false).as_ref().map_or(H256::new(), |a|a.storage_at(&self.db, key))	
 	}

 	/// Mutate storage of account `a` so that it is `value` for `key`.
 	pub fn code(&self, a: &Address) -> Option<Bytes> {
-		self.get(a, true).as_ref().map(|a|a.code().map(|x|x.to_vec())).unwrap_or(None)
+		self.get(a, true).as_ref().map_or(None, |a|a.code().map(|x|x.to_vec()))
 	}

 	/// Add `incr` to the balance of account `a`.
@@ -170,6 +170,7 @@ impl State {

 	/// Commit accounts to SecTrieDBMut. This is similar to cpp-ethereum's dev::eth::commit.
 	/// `accounts` is mutable because we may need to commit the code or storage and record that.
+	#[allow(match_ref_pats)]
 	pub fn commit_into(db: &mut HashDB, root: &mut H256, accounts: &mut HashMap<Address, Option<Account>>) {
 		// first, commit the sub trees.
 		// TODO: is this necessary or can we dispense with the `ref mut a` for just `a`?
@@ -186,9 +187,9 @@ impl State {
 		{
 			let mut trie = SecTrieDBMut::from_existing(db, root);
 			for (address, ref a) in accounts.iter() {
-				match a {
-					&&Some(ref account) => trie.insert(address, &account.rlp()),
-					&&None => trie.remove(address),
+				match **a {
+					Some(ref account) => trie.insert(address, &account.rlp()),
+					None => trie.remove(address),
 				}
 			}
 		}
@@ -210,7 +211,7 @@ impl State {
 	pub fn to_hashmap_pod(&self) -> HashMap<Address, PodAccount> {
 		// TODO: handle database rather than just the cache.
 		self.cache.borrow().iter().fold(HashMap::new(), |mut m, (add, opt)| {
-			if let &Some(ref acc) = opt {
+			if let Some(ref acc) = *opt {
 				m.insert(add.clone(), PodAccount::from_account(acc));
 			}
 			m
@@ -221,7 +222,7 @@ impl State {
 	pub fn to_pod(&self) -> PodState {
 		// TODO: handle database rather than just the cache.
 		PodState::new(self.cache.borrow().iter().fold(BTreeMap::new(), |mut m, (add, opt)| {
-			if let &Some(ref acc) = opt {
+			if let Some(ref acc) = *opt {
 				m.insert(add.clone(), PodAccount::from_account(acc));
 			}
 			m
--- a/src/state_diff.rs
+++ b/src/state_diff.rs
@@ -15,7 +15,7 @@ impl StateDiff {

 impl fmt::Display for StateDiff {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-		for (add, acc) in self.0.iter() {
+		for (add, acc) in &self.0 {
 			try!(write!(f, "{} {}: {}", acc.existance(), add, acc));
 		}
 		Ok(())
--- a/src/sync/chain.rs
+++ b/src/sync/chain.rs
@@ -107,6 +107,10 @@ pub struct SyncStatus {
 	pub blocks_total: usize,
 	/// Number of blocks downloaded so far.
 	pub blocks_received: usize,
+	/// Total number of connected peers
+	pub num_peers: usize,
+	/// Total number of active peers
+	pub num_active_peers: usize,
 }

 #[derive(PartialEq, Eq, Debug)]
@@ -195,8 +199,10 @@ impl ChainSync {
 			start_block_number: self.starting_block,
 			last_imported_block_number: self.last_imported_block,
 			highest_block_number: self.highest_block,
-			blocks_total: (self.last_imported_block - self.starting_block) as usize,
-			blocks_received: (self.highest_block - self.starting_block) as usize,
+			blocks_received: (self.last_imported_block - self.starting_block) as usize,
+			blocks_total: (self.highest_block - self.starting_block) as usize,
+			num_peers: self.peers.len(),
+			num_active_peers: self.peers.values().filter(|p| p.asking != PeerAsking::Nothing).count(),
 		}
 	}

@@ -212,7 +218,7 @@ impl ChainSync {
 		self.downloading_bodies.clear();
 		self.headers.clear();
 		self.bodies.clear();
-		for (_, ref mut p) in self.peers.iter_mut() {
+		for (_, ref mut p) in &mut self.peers {
 			p.asking_blocks.clear();
 		}
 		self.header_ids.clear();
@@ -268,6 +274,7 @@ impl ChainSync {
 		Ok(())
 	}

+	#[allow(cyclomatic_complexity)]
 	/// Called by peer once it has new block headers during sync
 	fn on_peer_block_headers(&mut self, io: &mut SyncIo, peer_id: PeerId, r: &UntrustedRlp) -> Result<(), PacketDecodeError> {
 		self.reset_peer_asking(peer_id, PeerAsking::BlockHeaders);
@@ -375,7 +382,7 @@ impl ChainSync {
 				transactions_root: tx_root,
 				uncles: uncles
 			};
-			match self.header_ids.get(&header_id).map(|n| *n) {
+			match self.header_ids.get(&header_id).cloned() {
 				Some(n) => {
 					self.header_ids.remove(&header_id);
 					self.bodies.insert_item(n, body.as_raw().to_vec());
@@ -424,6 +431,10 @@ impl ChainSync {
 			let peer_difficulty = self.peers.get_mut(&peer_id).expect("ChainSync: unknown peer").difficulty;
 			if difficulty > peer_difficulty {
 				trace!(target: "sync", "Received block {:?}  with no known parent. Peer needs syncing...", h);
+				{
+					let peer = self.peers.get_mut(&peer_id).expect("ChainSync: unknown peer");
+					peer.latest = header_view.sha3();
+				}
 				self.sync_peer(io, peer_id, true);
 			}
 		}
@@ -464,6 +475,9 @@ impl ChainSync {
 				}
 			}
 		};
+		if max_height != x!(0) {
+			self.sync_peer(io, peer_id, true);
+		}
 		Ok(())
 	}

@@ -540,7 +554,7 @@ impl ChainSync {
 	fn request_blocks(&mut self, io: &mut SyncIo, peer_id: PeerId) {
 		self.clear_peer_download(peer_id);

-		if io.chain().queue_status().full {
+		if io.chain().queue_info().full {
 			self.pause_sync();
 			return;
 		}
@@ -699,16 +713,13 @@ impl ChainSync {
 	/// Used to recover from an error and re-download parts of the chain detected as bad.
 	fn remove_downloaded_blocks(&mut self, start: BlockNumber) {
 		for n in self.headers.get_tail(&start) {
-			match self.headers.find_item(&n) {
-				Some(ref header_data) => {
-					let header_to_delete = HeaderView::new(&header_data.data);
-					let header_id = HeaderId {
-						transactions_root: header_to_delete.transactions_root(),
-						uncles: header_to_delete.uncles_hash()
-					};
-					self.header_ids.remove(&header_id);
-				},
-				None => {}
+			if let Some(ref header_data) = self.headers.find_item(&n) {
+				let header_to_delete = HeaderView::new(&header_data.data);
+				let header_id = HeaderId {
+					transactions_root: header_to_delete.transactions_root(),
+					uncles: header_to_delete.uncles_hash()
+				};
+				self.header_ids.remove(&header_id);
 			}
 			self.downloading_bodies.remove(&n);
 			self.downloading_headers.remove(&n);
@@ -796,12 +807,9 @@ impl ChainSync {
 		packet.append(&chain.best_block_hash);
 		packet.append(&chain.genesis_hash);
 		//TODO: handle timeout for status request
-		match io.send(peer_id, STATUS_PACKET, packet.out()) {
-			Err(e) => {
-				warn!(target:"sync", "Error sending status request: {:?}", e);
-				io.disable_peer(peer_id);
-			}
-			Ok(_) => ()
+		if let Err(e) = io.send(peer_id, STATUS_PACKET, packet.out()) {
+			warn!(target:"sync", "Error sending status request: {:?}", e);
+			io.disable_peer(peer_id);
 		}
 	}

@@ -837,12 +845,9 @@ impl ChainSync {
 		let mut data = Bytes::new();
 		let inc = (skip + 1) as BlockNumber;
 		while number <= last && number > 0 && count < max_count {
-			match io.chain().block_header_at(number) {
-				Some(mut hdr) => {
-					data.append(&mut hdr);
-					count += 1;
-				}
-				None => {}
+			if let Some(mut hdr) = io.chain().block_header_at(number) {
+				data.append(&mut hdr);
+				count += 1;
 			}
 			if reverse {
 				if number <= inc {
@@ -874,12 +879,9 @@ impl ChainSync {
 		let mut added = 0usize;
 		let mut data = Bytes::new();
 		for i in 0..count {
-			match io.chain().block_body(&try!(r.val_at::<H256>(i))) {
-				Some(mut hdr) => {
-					data.append(&mut hdr);
-					added += 1;
-				}
-				None => {}
+			if let Some(mut hdr) = io.chain().block_body(&try!(r.val_at::<H256>(i))) {
+				data.append(&mut hdr);
+				added += 1;
 			}
 		}
 		let mut rlp = RlpStream::new_list(added);
@@ -901,12 +903,9 @@ impl ChainSync {
 		let mut added = 0usize;
 		let mut data = Bytes::new();
 		for i in 0..count {
-			match io.chain().state_data(&try!(r.val_at::<H256>(i))) {
-				Some(mut hdr) => {
-					data.append(&mut hdr);
-					added += 1;
-				}
-				None => {}
+			if let Some(mut hdr) = io.chain().state_data(&try!(r.val_at::<H256>(i))) {
+				data.append(&mut hdr);
+				added += 1;
 			}
 		}
 		let mut rlp = RlpStream::new_list(added);
@@ -927,12 +926,9 @@ impl ChainSync {
 		let mut added = 0usize;
 		let mut data = Bytes::new();
 		for i in 0..count {
-			match io.chain().block_receipts(&try!(r.val_at::<H256>(i))) {
-				Some(mut hdr) => {
-					data.append(&mut hdr);
-					added += 1;
-				}
-				None => {}
+			if let Some(mut hdr) = io.chain().block_receipts(&try!(r.val_at::<H256>(i))) {
+				data.append(&mut hdr);
+				added += 1;
 			}
 		}
 		let mut rlp = RlpStream::new_list(added);
@@ -967,7 +963,7 @@ impl ChainSync {
 	}

 	/// Maintain other peers. Send out any new blocks and transactions
-	pub fn maintain_sync(&mut self, _io: &mut SyncIo) {
+	pub fn _maintain_sync(&mut self, _io: &mut SyncIo) {
 	}
 }

--- a/src/sync/io.rs
+++ b/src/sync/io.rs
@@ -1,7 +1,7 @@
 use client::BlockChainClient;
 use util::{NetworkContext, PeerId, PacketId,};
 use util::error::UtilError;
-use sync::SyncMessage;
+use service::SyncMessage;

 /// IO interface for the syning handler.
 /// Provides peer connection management and an interface to the blockchain client.
@@ -14,7 +14,7 @@ pub trait SyncIo {
 	/// Send a packet to a peer.
 	fn send(&mut self, peer_id: PeerId, packet_id: PacketId, data: Vec<u8>) -> Result<(), UtilError>;
 	/// Get the blockchain
-	fn chain<'s>(&'s mut self) -> &'s mut BlockChainClient;
+	fn chain(&self) -> &BlockChainClient;
 	/// Returns peer client identifier string
 	fn peer_info(&self, peer_id: PeerId) -> String {
 		peer_id.to_string()
@@ -22,14 +22,14 @@ pub trait SyncIo {
 }

 /// Wraps `NetworkContext` and the blockchain client
-pub struct NetSyncIo<'s, 'h, 'io> where 'h: 's, 'io: 'h {
-	network: &'s mut NetworkContext<'h, 'io, SyncMessage>,
-	chain: &'s mut BlockChainClient
+pub struct NetSyncIo<'s, 'h> where 'h: 's {
+	network: &'s NetworkContext<'h, SyncMessage>,
+	chain: &'s BlockChainClient
 }

-impl<'s, 'h, 'io> NetSyncIo<'s, 'h, 'io> {
+impl<'s, 'h> NetSyncIo<'s, 'h> {
 	/// Creates a new instance from the `NetworkContext` and the blockchain client reference.
-	pub fn new(network: &'s mut NetworkContext<'h, 'io, SyncMessage>, chain: &'s mut BlockChainClient) -> NetSyncIo<'s,'h,'io> {
+	pub fn new(network: &'s NetworkContext<'h, SyncMessage>, chain: &'s BlockChainClient) -> NetSyncIo<'s, 'h> {
 		NetSyncIo {
 			network: network,
 			chain: chain,
@@ -37,7 +37,7 @@ impl<'s, 'h, 'io> NetSyncIo<'s, 'h, 'io> {
 	}
 }

-impl<'s, 'h, 'op> SyncIo for NetSyncIo<'s, 'h, 'op> {
+impl<'s, 'h> SyncIo for NetSyncIo<'s, 'h> {
 	fn disable_peer(&mut self, peer_id: PeerId) {
 		self.network.disable_peer(peer_id);
 	}
@@ -50,7 +50,7 @@ impl<'s, 'h, 'op> SyncIo for NetSyncIo<'s, 'h, 'op> {
 		self.network.send(peer_id, packet_id, data)
 	}

-	fn chain<'a>(&'a mut self) -> &'a mut BlockChainClient {
+	fn chain(&self) -> &BlockChainClient {
 		self.chain
 	}

--- a/src/sync/mod.rs
+++ b/src/sync/mod.rs
@@ -17,7 +17,7 @@
 /// fn main() {
 /// 	let mut service = NetworkService::start().unwrap();
 /// 	let dir = env::temp_dir();
-/// 	let client = Arc::new(Client::new(ethereum::new_frontier(), &dir).unwrap());
+/// 	let client = Client::new(ethereum::new_frontier(), &dir, service.io().channel()).unwrap();
 /// 	EthSync::register(&mut service, client);
 /// }
 /// ```
@@ -25,10 +25,9 @@
 use std::ops::*;
 use std::sync::*;
 use client::Client;
-use util::network::{NetworkProtocolHandler, NetworkService, NetworkContext, PeerId, NetworkIoMessage};
-use util::TimerToken;
-use util::Bytes;
+use util::network::{NetworkProtocolHandler, NetworkService, NetworkContext, PeerId};
 use sync::chain::ChainSync;
+use service::SyncMessage;
 use sync::io::NetSyncIo;

 mod chain;
@@ -38,76 +37,57 @@ mod range_collection;
 #[cfg(test)]
 mod tests;

-/// Message type for external events
-pub enum SyncMessage {
-	/// New block has been imported into the blockchain
-	NewChainBlock(Bytes),
-	/// A block is ready 
-	BlockVerified,
-}
-
-/// TODO [arkpar] Please document me
-pub type NetSyncMessage = NetworkIoMessage<SyncMessage>;
-
 /// Ethereum network protocol handler
 pub struct EthSync {
 	/// Shared blockchain client. TODO: this should evetually become an IPC endpoint
-	chain: Arc<RwLock<Client>>,
+	chain: Arc<Client>,
 	/// Sync strategy
-	sync: ChainSync
+	sync: RwLock<ChainSync>
 }

 pub use self::chain::SyncStatus;

 impl EthSync {
 	/// Creates and register protocol with the network service
-	pub fn register(service: &mut NetworkService<SyncMessage>, chain: Arc<RwLock<Client>>) {
-		let sync = Box::new(EthSync {
+	pub fn register(service: &mut NetworkService<SyncMessage>, chain: Arc<Client>) -> Arc<EthSync> {
+		let sync = Arc::new(EthSync {
 			chain: chain,
-			sync: ChainSync::new(),
+			sync: RwLock::new(ChainSync::new()),
 		});
-		service.register_protocol(sync, "eth", &[62u8, 63u8]).expect("Error registering eth protocol handler");
+		service.register_protocol(sync.clone(), "eth", &[62u8, 63u8]).expect("Error registering eth protocol handler");
+		sync
 	}

 	/// Get sync status
 	pub fn status(&self) -> SyncStatus {
-		self.sync.status()
+		self.sync.read().unwrap().status()
 	}

 	/// Stop sync
 	pub fn stop(&mut self, io: &mut NetworkContext<SyncMessage>) {
-		self.sync.abort(&mut NetSyncIo::new(io, self.chain.write().unwrap().deref_mut()));
+		self.sync.write().unwrap().abort(&mut NetSyncIo::new(io, self.chain.deref()));
 	}

 	/// Restart sync
 	pub fn restart(&mut self, io: &mut NetworkContext<SyncMessage>) {
-		self.sync.restart(&mut NetSyncIo::new(io, self.chain.write().unwrap().deref_mut()));
+		self.sync.write().unwrap().restart(&mut NetSyncIo::new(io, self.chain.deref()));
 	}
 }

 impl NetworkProtocolHandler<SyncMessage> for EthSync {
-	fn initialize(&mut self, io: &mut NetworkContext<SyncMessage>) {
-		self.sync.restart(&mut NetSyncIo::new(io, self.chain.write().unwrap().deref_mut()));
-		io.register_timer(1000).unwrap();
+	fn initialize(&self, _io: &NetworkContext<SyncMessage>) {
 	}

-	fn read(&mut self, io: &mut NetworkContext<SyncMessage>, peer: &PeerId, packet_id: u8, data: &[u8]) {
-		self.sync.on_packet(&mut NetSyncIo::new(io, self.chain.write().unwrap().deref_mut()) , *peer, packet_id, data);
+	fn read(&self, io: &NetworkContext<SyncMessage>, peer: &PeerId, packet_id: u8, data: &[u8]) {
+		self.sync.write().unwrap().on_packet(&mut NetSyncIo::new(io, self.chain.deref()) , *peer, packet_id, data);
 	}

-	fn connected(&mut self, io: &mut NetworkContext<SyncMessage>, peer: &PeerId) {
-		self.sync.on_peer_connected(&mut NetSyncIo::new(io, self.chain.write().unwrap().deref_mut()), *peer);
+	fn connected(&self, io: &NetworkContext<SyncMessage>, peer: &PeerId) {
+		self.sync.write().unwrap().on_peer_connected(&mut NetSyncIo::new(io, self.chain.deref()), *peer);
 	}

-	fn disconnected(&mut self, io: &mut NetworkContext<SyncMessage>, peer: &PeerId) {
-		self.sync.on_peer_aborting(&mut NetSyncIo::new(io, self.chain.write().unwrap().deref_mut()), *peer);
-	}
-
-	fn timeout(&mut self, io: &mut NetworkContext<SyncMessage>, _timer: TimerToken) {
-		self.sync.maintain_sync(&mut NetSyncIo::new(io, self.chain.write().unwrap().deref_mut()));
-	}
-
-	fn message(&mut self, _io: &mut NetworkContext<SyncMessage>, _message: &SyncMessage) {
+	fn disconnected(&self, io: &NetworkContext<SyncMessage>, peer: &PeerId) {
+		self.sync.write().unwrap().on_peer_aborting(&mut NetSyncIo::new(io, self.chain.deref()), *peer);
 	}
 }

--- a/src/sync/range_collection.rs
+++ b/src/sync/range_collection.rs
@@ -29,7 +29,7 @@ pub trait RangeCollection<K, V> {
 	/// Remove all elements >= `tail`
 	fn insert_item(&mut self, key: K, value: V);
 	/// Get an iterator over ranges
-	fn range_iter<'c>(&'c self) -> RangeIterator<'c, K, V>;
+	fn range_iter(& self) -> RangeIterator<K, V>;
 }

 /// Range iterator. For each range yelds a key for the first element of the range and a vector of values.
@@ -60,7 +60,7 @@ impl<'c, K:'c, V:'c> Iterator for RangeIterator<'c, K, V> where K: Add<Output =
 }

 impl<K, V> RangeCollection<K, V> for Vec<(K, Vec<V>)> where K: Ord + PartialEq + Add<Output = K> + Sub<Output = K> + Copy + FromUsize + ToUsize {
-	fn range_iter<'c>(&'c self) -> RangeIterator<'c, K, V> {
+	fn range_iter(&self) -> RangeIterator<K, V> {
 		RangeIterator {
 			range: self.len(),
 			collection: self
@@ -191,6 +191,7 @@ impl<K, V> RangeCollection<K, V> for Vec<(K, Vec<V>)> where K: Ord + PartialEq +
 }

 #[test]
+#[allow(cyclomatic_complexity)]
 fn test_range() {
 	use std::cmp::{Ordering};

--- a/src/sync/tests.rs
+++ b/src/sync/tests.rs
@@ -1,38 +1,40 @@
 use util::*;
-use client::{BlockChainClient, BlockStatus, TreeRoute, BlockQueueStatus, BlockChainInfo};
+use client::{BlockChainClient, BlockStatus, TreeRoute, BlockChainInfo};
+use block_queue::BlockQueueInfo;
 use header::{Header as BlockHeader, BlockNumber};
 use error::*;
 use sync::io::SyncIo;
 use sync::chain::ChainSync;

 struct TestBlockChainClient {
-	blocks: HashMap<H256, Bytes>,
- 	numbers: HashMap<usize, H256>,
+	blocks: RwLock<HashMap<H256, Bytes>>,
+ 	numbers: RwLock<HashMap<usize, H256>>,
 	genesis_hash: H256,
-	last_hash: H256,
-	difficulty: U256
+	last_hash: RwLock<H256>,
+	difficulty: RwLock<U256>,
 }

 impl TestBlockChainClient {
 	fn new() -> TestBlockChainClient {

 		let mut client = TestBlockChainClient {
-			blocks: HashMap::new(),
-			numbers: HashMap::new(),
+			blocks: RwLock::new(HashMap::new()),
+			numbers: RwLock::new(HashMap::new()),
 			genesis_hash: H256::new(),
-			last_hash: H256::new(),
-			difficulty: From::from(0),
+			last_hash: RwLock::new(H256::new()),
+			difficulty: RwLock::new(From::from(0)),
 		};
 		client.add_blocks(1, true); // add genesis block
-		client.genesis_hash = client.last_hash.clone();
+		client.genesis_hash = client.last_hash.read().unwrap().clone();
 		client
 	}

 	pub fn add_blocks(&mut self, count: usize, empty: bool) {
-		for n in self.numbers.len()..(self.numbers.len() + count) {
+		let len = self.numbers.read().unwrap().len();
+		for n in len..(len + count) {
 			let mut header = BlockHeader::new();
 			header.difficulty = From::from(n);
-			header.parent_hash = self.last_hash.clone();
+			header.parent_hash = self.last_hash.read().unwrap().clone();
 			header.number = n as BlockNumber;
 			let mut uncles = RlpStream::new_list(if empty {0} else {1});
 			if !empty {
@@ -50,12 +52,12 @@ impl TestBlockChainClient {

 impl BlockChainClient for TestBlockChainClient {
 	fn block_header(&self, h: &H256) -> Option<Bytes> {
-		self.blocks.get(h).map(|r| Rlp::new(r).at(0).as_raw().to_vec())
+		self.blocks.read().unwrap().get(h).map(|r| Rlp::new(r).at(0).as_raw().to_vec())

 	}

 	fn block_body(&self, h: &H256) -> Option<Bytes> {
-		self.blocks.get(h).map(|r| {
+		self.blocks.read().unwrap().get(h).map(|r| {
 			let mut stream = RlpStream::new_list(2);
 			stream.append_raw(Rlp::new(&r).at(1).as_raw(), 1);
 			stream.append_raw(Rlp::new(&r).at(2).as_raw(), 1);
@@ -64,30 +66,30 @@ impl BlockChainClient for TestBlockChainClient {
 	}

 	fn block(&self, h: &H256) -> Option<Bytes> {
-		self.blocks.get(h).map(|b| b.clone())
+		self.blocks.read().unwrap().get(h).cloned()
 	}

 	fn block_status(&self, h: &H256) -> BlockStatus {
-		match self.blocks.get(h) {
+		match self.blocks.read().unwrap().get(h) {
 			Some(_) => BlockStatus::InChain,
 			None => BlockStatus::Unknown
 		}
 	}

 	fn block_header_at(&self, n: BlockNumber) -> Option<Bytes> {
-		self.numbers.get(&(n as usize)).and_then(|h| self.block_header(h))
+		self.numbers.read().unwrap().get(&(n as usize)).and_then(|h| self.block_header(h))
 	}

 	fn block_body_at(&self, n: BlockNumber) -> Option<Bytes> {
-		self.numbers.get(&(n as usize)).and_then(|h| self.block_body(h))
+		self.numbers.read().unwrap().get(&(n as usize)).and_then(|h| self.block_body(h))
 	}

 	fn block_at(&self, n: BlockNumber) -> Option<Bytes> {
-		self.numbers.get(&(n as usize)).map(|h| self.blocks.get(h).unwrap().clone())
+		self.numbers.read().unwrap().get(&(n as usize)).map(|h| self.blocks.read().unwrap().get(h).unwrap().clone())
 	}

 	fn block_status_at(&self, n: BlockNumber) -> BlockStatus {
-		if (n as usize) < self.blocks.len() {
+		if (n as usize) < self.blocks.read().unwrap().len() {
 			BlockStatus::InChain
 		} else {
 			BlockStatus::Unknown
@@ -110,14 +112,14 @@ impl BlockChainClient for TestBlockChainClient {
 		None
 	}

-	fn import_block(&mut self, b: Bytes) -> ImportResult {
+	fn import_block(&self, b: Bytes) -> ImportResult {
 		let header = Rlp::new(&b).val_at::<BlockHeader>(0);
 		let number: usize = header.number as usize;
-		if number > self.blocks.len() {
-			panic!("Unexpected block number. Expected {}, got {}", self.blocks.len(), number);
+		if number > self.blocks.read().unwrap().len() {
+			panic!("Unexpected block number. Expected {}, got {}", self.blocks.read().unwrap().len(), number);
 		}
 		if number > 0 {
-			match self.blocks.get(&header.parent_hash) {
+			match self.blocks.read().unwrap().get(&header.parent_hash) {
 				Some(parent) => {
 					let parent = Rlp::new(parent).val_at::<BlockHeader>(0);
 					if parent.number != (header.number - 1) {
@@ -129,43 +131,46 @@ impl BlockChainClient for TestBlockChainClient {
 				}
 			}
 		}
-		if number == self.numbers.len() {
-			self.difficulty = self.difficulty + header.difficulty;
-			self.last_hash = header.hash();
-			self.blocks.insert(header.hash(), b);
-			self.numbers.insert(number, header.hash());
+		let len = self.numbers.read().unwrap().len();
+		if number == len {
+			*self.difficulty.write().unwrap().deref_mut() += header.difficulty;
+			mem::replace(self.last_hash.write().unwrap().deref_mut(), header.hash());
+			self.blocks.write().unwrap().insert(header.hash(), b);
+			self.numbers.write().unwrap().insert(number, header.hash());
 			let mut parent_hash = header.parent_hash;
 			if number > 0 {
 				let mut n = number - 1;
-				while n > 0 && self.numbers[&n] != parent_hash {
-					*self.numbers.get_mut(&n).unwrap() = parent_hash.clone();
+				while n > 0 && self.numbers.read().unwrap()[&n] != parent_hash {
+					*self.numbers.write().unwrap().get_mut(&n).unwrap() = parent_hash.clone();
 					n -= 1;
-					parent_hash = Rlp::new(&self.blocks[&parent_hash]).val_at::<BlockHeader>(0).parent_hash;
+					parent_hash = Rlp::new(&self.blocks.read().unwrap()[&parent_hash]).val_at::<BlockHeader>(0).parent_hash;
 				}
 			}
 		}
 		else {
-			self.blocks.insert(header.hash(), b.to_vec());
+			self.blocks.write().unwrap().insert(header.hash(), b.to_vec());
 		}
 		Ok(())
 	}

-	fn queue_status(&self) -> BlockQueueStatus {
-		BlockQueueStatus {
+	fn queue_info(&self) -> BlockQueueInfo {
+		BlockQueueInfo {
 			full: false,
+			verified_queue_size: 0,
+			unverified_queue_size: 0,
 		}
 	}

-	fn clear_queue(&mut self) {
+	fn clear_queue(&self) {
 	}

 	fn chain_info(&self) -> BlockChainInfo {
 		BlockChainInfo {
-			total_difficulty: self.difficulty,
-			pending_total_difficulty: self.difficulty,
+			total_difficulty: *self.difficulty.read().unwrap(),
+			pending_total_difficulty: *self.difficulty.read().unwrap(),
 			genesis_hash: self.genesis_hash.clone(),
-			best_block_hash: self.last_hash.clone(),
-			best_block_number: self.blocks.len() as BlockNumber - 1,
+			best_block_hash: self.last_hash.read().unwrap().clone(),
+			best_block_number: self.blocks.read().unwrap().len() as BlockNumber - 1,
 		}
 	}
 }
@@ -208,7 +213,7 @@ impl<'p> SyncIo for TestIo<'p> {
 		Ok(())
 	}

-	fn chain<'a>(&'a mut self) -> &'a mut BlockChainClient {
+	fn chain(&self) -> &BlockChainClient {
 		self.chain
 	}
 }
@@ -265,17 +270,14 @@ impl TestNet {

 	pub fn sync_step(&mut self) {
 		for peer in 0..self.peers.len() {
-			match self.peers[peer].queue.pop_front() {
-				Some(packet) => {
-					let mut p = self.peers.get_mut(packet.recipient).unwrap();
-					trace!("--- {} -> {} ---", peer, packet.recipient);
-					p.sync.on_packet(&mut TestIo::new(&mut p.chain, &mut p.queue, Some(peer as PeerId)), peer as PeerId, packet.packet_id, &packet.data);
-					trace!("----------------");
-				},
-				None => {}
+			if let Some(packet) = self.peers[peer].queue.pop_front() {
+				let mut p = self.peers.get_mut(packet.recipient).unwrap();
+				trace!("--- {} -> {} ---", peer, packet.recipient);
+				p.sync.on_packet(&mut TestIo::new(&mut p.chain, &mut p.queue, Some(peer as PeerId)), peer as PeerId, packet.packet_id, &packet.data);
+				trace!("----------------");
 			}
 			let mut p = self.peers.get_mut(peer).unwrap();
-			p.sync.maintain_sync(&mut TestIo::new(&mut p.chain, &mut p.queue, None));
+			p.sync._maintain_sync(&mut TestIo::new(&mut p.chain, &mut p.queue, None));
 		}
 	}

@@ -300,7 +302,7 @@ fn full_sync_two_peers() {
 	net.peer_mut(2).chain.add_blocks(1000, false);
 	net.sync();
 	assert!(net.peer(0).chain.block_at(1000).is_some());
-	assert_eq!(net.peer(0).chain.blocks, net.peer(1).chain.blocks);
+	assert_eq!(net.peer(0).chain.blocks.read().unwrap().deref(), net.peer(1).chain.blocks.read().unwrap().deref());
 }

 #[test]
@@ -313,7 +315,7 @@ fn full_sync_empty_blocks() {
 	}
 	net.sync();
 	assert!(net.peer(0).chain.block_at(1000).is_some());
-	assert_eq!(net.peer(0).chain.blocks, net.peer(1).chain.blocks);
+	assert_eq!(net.peer(0).chain.blocks.read().unwrap().deref(), net.peer(1).chain.blocks.read().unwrap().deref());
 }

 #[test]
@@ -329,9 +331,9 @@ fn forked_sync() {
 	net.peer_mut(1).chain.add_blocks(100, false); //fork between 1 and 2
 	net.peer_mut(2).chain.add_blocks(10, true);
 	// peer 1 has the best chain of 601 blocks
-	let peer1_chain = net.peer(1).chain.numbers.clone();
+	let peer1_chain = net.peer(1).chain.numbers.read().unwrap().clone();
 	net.sync();
-	assert_eq!(net.peer(0).chain.numbers, peer1_chain);
-	assert_eq!(net.peer(1).chain.numbers, peer1_chain);
-	assert_eq!(net.peer(2).chain.numbers, peer1_chain);
+	assert_eq!(net.peer(0).chain.numbers.read().unwrap().deref(), &peer1_chain);
+	assert_eq!(net.peer(1).chain.numbers.read().unwrap().deref(), &peer1_chain);
+	assert_eq!(net.peer(2).chain.numbers.read().unwrap().deref(), &peer1_chain);
 }
--- a/src/tests/executive.rs
+++ b/src/tests/executive.rs
@@ -168,7 +168,7 @@ fn do_json_test_for(vm: &VMType, json_data: &[u8]) -> Vec<String> {
 		let mut fail = false;
 		//let mut fail_unless = |cond: bool| if !cond && !fail { failed.push(name.to_string()); fail = true };
 		let mut fail_unless = |cond: bool, s: &str | if !cond && !fail { 
-			failed.push(format!("[{}] {}: {}", vm, name.to_string(), s)); 
+			failed.push(format!("[{}] {}: {}", vm, name, s)); 
 			fail = true 
 		};
 	
@@ -187,15 +187,9 @@ fn do_json_test_for(vm: &VMType, json_data: &[u8]) -> Vec<String> {
 			BTreeMap::from_json(&s["storage"]).into_iter().foreach(|(k, v)| state.set_storage(&address, k, v));
 		});

-		let mut info = EnvInfo::new();
-
-		test.find("env").map(|env| {
-			info.author = xjson!(&env["currentCoinbase"]);
-			info.difficulty = xjson!(&env["currentDifficulty"]);
-			info.gas_limit = xjson!(&env["currentGasLimit"]);
-			info.number = xjson!(&env["currentNumber"]);
-			info.timestamp = xjson!(&env["currentTimestamp"]);
-		});
+		let info = test.find("env").map(|env| {
+			EnvInfo::from_json(env)
+		}).unwrap_or_default();

 		let engine = TestEngine::new(1, vm.clone());

@@ -245,7 +239,7 @@ fn do_json_test_for(vm: &VMType, json_data: &[u8]) -> Vec<String> {
 				test.find("post").map(|pre| for (addr, s) in pre.as_object().unwrap() {
 					let address = Address::from(addr.as_ref());

-					fail_unless(state.code(&address).unwrap_or(vec![]) == Bytes::from_json(&s["code"]), "code is incorrect");
+					fail_unless(state.code(&address).unwrap_or_else(|| vec![]) == Bytes::from_json(&s["code"]), "code is incorrect");
 					fail_unless(state.balance(&address) == xjson!(&s["balance"]), "balance is incorrect");
 					fail_unless(state.nonce(&address) == xjson!(&s["nonce"]), "nonce is incorrect");
 					BTreeMap::from_json(&s["storage"]).iter().foreach(|(k, v)| fail_unless(&state.storage_at(&address, &k) == v, "storage is incorrect"));
@@ -266,7 +260,7 @@ fn do_json_test_for(vm: &VMType, json_data: &[u8]) -> Vec<String> {
 	}


-	for f in failed.iter() {
+	for f in &failed {
 		println!("FAILED: {:?}", f);
 	}

@@ -277,11 +271,10 @@ fn do_json_test_for(vm: &VMType, json_data: &[u8]) -> Vec<String> {
 declare_test!{ExecutiveTests_vmArithmeticTest, "VMTests/vmArithmeticTest"}
 declare_test!{ExecutiveTests_vmBitwiseLogicOperationTest, "VMTests/vmBitwiseLogicOperationTest"}
 // this one crashes with some vm internal error. Separately they pass.
-declare_test_ignore!{ExecutiveTests_vmBlockInfoTest, "VMTests/vmBlockInfoTest"}
+declare_test!{ignore => ExecutiveTests_vmBlockInfoTest, "VMTests/vmBlockInfoTest"}
 declare_test!{ExecutiveTests_vmEnvironmentalInfoTest, "VMTests/vmEnvironmentalInfoTest"}
 declare_test!{ExecutiveTests_vmIOandFlowOperationsTest, "VMTests/vmIOandFlowOperationsTest"}
-// this one take way too long.
-declare_test_ignore!{ExecutiveTests_vmInputLimits, "VMTests/vmInputLimits"}
+declare_test!{heavy => ExecutiveTests_vmInputLimits, "VMTests/vmInputLimits"}
 declare_test!{ExecutiveTests_vmLogTest, "VMTests/vmLogTest"}
 declare_test!{ExecutiveTests_vmPerformanceTest, "VMTests/vmPerformanceTest"}
 declare_test!{ExecutiveTests_vmPushDupSwapTest, "VMTests/vmPushDupSwapTest"}
--- a/src/tests/state.rs
+++ b/src/tests/state.rs
@@ -15,7 +15,7 @@ fn do_json_test(json_data: &[u8]) -> Vec<String> {
 		let mut fail = false;
 		{
 			let mut fail_unless = |cond: bool| if !cond && !fail {
-				failed.push(name.to_string());
+				failed.push(name.clone());
 				flush(format!("FAIL\n"));
 				fail = true;
 				true
@@ -73,20 +73,20 @@ fn do_json_test(json_data: &[u8]) -> Vec<String> {

 declare_test!{StateTests_stBlockHashTest, "StateTests/stBlockHashTest"}
 declare_test!{StateTests_stCallCodes, "StateTests/stCallCodes"}
-declare_test_ignore!{StateTests_stCallCreateCallCodeTest, "StateTests/stCallCreateCallCodeTest"}	//<< Out of stack
-declare_test!{StateTests_stDelegatecallTest, "StateTests/stDelegatecallTest"}						//<< FAIL - gas too high
+declare_test!{ignore => StateTests_stCallCreateCallCodeTest, "StateTests/stCallCreateCallCodeTest"}	//<< Out of stack
+declare_test!{StateTests_stDelegatecallTest, "StateTests/stDelegatecallTest"}
 declare_test!{StateTests_stExample, "StateTests/stExample"}
 declare_test!{StateTests_stInitCodeTest, "StateTests/stInitCodeTest"}
 declare_test!{StateTests_stLogTests, "StateTests/stLogTests"}
-declare_test!{StateTests_stMemoryStressTest, "StateTests/stMemoryStressTest"}
-declare_test!{StateTests_stMemoryTest, "StateTests/stMemoryTest"}
+declare_test!{heavy => StateTests_stMemoryStressTest, "StateTests/stMemoryStressTest"}
+declare_test!{heavy => StateTests_stMemoryTest, "StateTests/stMemoryTest"}
 declare_test!{StateTests_stPreCompiledContracts, "StateTests/stPreCompiledContracts"}
-declare_test_ignore!{StateTests_stQuadraticComplexityTest, "StateTests/stQuadraticComplexityTest"}	//<< Too long
-declare_test_ignore!{StateTests_stRecursiveCreate, "StateTests/stRecursiveCreate"}					//<< Out of stack 
+declare_test!{heavy => StateTests_stQuadraticComplexityTest, "StateTests/stQuadraticComplexityTest"} //<< Too long
+declare_test!{ignore => StateTests_stRecursiveCreate, "StateTests/stRecursiveCreate"} //<< Out of stack 
 declare_test!{StateTests_stRefundTest, "StateTests/stRefundTest"}
 declare_test!{StateTests_stSolidityTest, "StateTests/stSolidityTest"}
-declare_test_ignore!{StateTests_stSpecialTest, "StateTests/stSpecialTest"}							//<< Signal 11
-declare_test_ignore!{StateTests_stSystemOperationsTest, "StateTests/stSystemOperationsTest"}		//<< Signal 11
+declare_test!{ignore => StateTests_stSpecialTest, "StateTests/stSpecialTest"} //<< Out of Stack
+declare_test!{ignore => StateTests_stSystemOperationsTest, "StateTests/stSystemOperationsTest"} //<< Out of stack
 declare_test!{StateTests_stTransactionTest, "StateTests/stTransactionTest"}
 declare_test!{StateTests_stTransitionTest, "StateTests/stTransitionTest"}
 declare_test!{StateTests_stWalletTest, "StateTests/stWalletTest"}
--- a/src/tests/test_common.rs
+++ b/src/tests/test_common.rs
@@ -1,24 +1,34 @@
 pub use common::*;

+macro_rules! test {
+	($name: expr) => {
+		assert!(do_json_test(include_bytes!(concat!("../../res/ethereum/tests/", $name, ".json"))).is_empty());
+	}
+}
+
 #[macro_export]
 macro_rules! declare_test {
-	($id: ident, $name: expr) => {
-		#[test]
-		#[allow(non_snake_case)]
-		fn $id() {
-			assert!(do_json_test(include_bytes!(concat!("../../res/ethereum/tests/", $name, ".json"))).len() == 0);
-		}
-	};
-}
-
-#[macro_export]
-macro_rules! declare_test_ignore {
-	($id: ident, $name: expr) => {
-		#[test]
+	(ignore => $id: ident, $name: expr) => {
 		#[ignore]
+		#[test]
 		#[allow(non_snake_case)]
 		fn $id() {
-			assert!(do_json_test(include_bytes!(concat!("../../res/ethereum/tests/", $name, ".json"))).len() == 0);
+			test!($name);
 		}
 	};
+	(heavy => $id: ident, $name: expr) => {
+		#[cfg(feature = "test-heavy")]
+		#[test]
+		#[allow(non_snake_case)]
+		fn $id() {
+			test!($name);
+		}
+	};
+	($id: ident, $name: expr) => {
+		#[test]
+		#[allow(non_snake_case)]
+		fn $id() {
+			test!($name);
+		}
+	}
 }
--- a/src/tests/transaction.rs
+++ b/src/tests/transaction.rs
@@ -9,13 +9,13 @@ fn do_json_test(json_data: &[u8]) -> Vec<String> {
 	let ot = RefCell::new(Transaction::new());
 	for (name, test) in json.as_object().unwrap() {
 		let mut fail = false;
-		let mut fail_unless = |cond: bool| if !cond && !fail { failed.push(name.to_string()); println!("Transaction: {:?}", ot.borrow()); fail = true };
+		let mut fail_unless = |cond: bool| if !cond && !fail { failed.push(name.clone()); println!("Transaction: {:?}", ot.borrow()); fail = true };
 		let schedule = match test.find("blocknumber")
 			.and_then(|j| j.as_string())
 			.and_then(|s| BlockNumber::from_str(s).ok())
 			.unwrap_or(0) { x if x < 900000 => &old_schedule, _ => &new_schedule };
 		let rlp = Bytes::from_json(&test["rlp"]);
-		let res = UntrustedRlp::new(&rlp).as_val().map_err(|e| From::from(e)).and_then(|t: Transaction| t.validate(schedule, schedule.have_delegate_call));
+		let res = UntrustedRlp::new(&rlp).as_val().map_err(From::from).and_then(|t: Transaction| t.validate(schedule, schedule.have_delegate_call));
 		fail_unless(test.find("transaction").is_none() == res.is_err());
 		if let (Some(&Json::Object(ref tx)), Some(&Json::String(ref expect_sender))) = (test.find("transaction"), test.find("sender")) {
 			let t = res.unwrap();
@@ -30,11 +30,11 @@ fn do_json_test(json_data: &[u8]) -> Vec<String> {
 				fail_unless(to == &xjson!(&tx["to"]));
 			} else {
 				*ot.borrow_mut() = t.clone();
-				fail_unless(Bytes::from_json(&tx["to"]).len() == 0);
+				fail_unless(Bytes::from_json(&tx["to"]).is_empty());
 			}
 		}
 	}
-	for f in failed.iter() {
+	for f in &failed {
 		println!("FAILED: {:?}", f);
 	}
 	failed
@@ -65,14 +65,14 @@ declare_test!{TransactionTests/ttTransactionTest}
 declare_test!{TransactionTests/tt10mbDataField}
 declare_test!{TransactionTests/ttWrongRLPTransaction}
 declare_test!{TransactionTests/Homestead/ttTransactionTest}
-declare_test!{TransactionTests/Homestead/tt10mbDataField}
+declare_test!{heavy => TransactionTests/Homestead/tt10mbDataField}
 declare_test!{TransactionTests/Homestead/ttWrongRLPTransaction}
 declare_test!{TransactionTests/RandomTests/tr201506052141PYTHON}*/

 declare_test!{TransactionTests_ttTransactionTest, "TransactionTests/ttTransactionTest"}
-declare_test_ignore!{TransactionTests_tt10mbDataField, "TransactionTests/tt10mbDataField"}
+declare_test!{heavy => TransactionTests_tt10mbDataField, "TransactionTests/tt10mbDataField"}
 declare_test!{TransactionTests_ttWrongRLPTransaction, "TransactionTests/ttWrongRLPTransaction"}
 declare_test!{TransactionTests_Homestead_ttTransactionTest, "TransactionTests/Homestead/ttTransactionTest"}
-declare_test_ignore!{TransactionTests_Homestead_tt10mbDataField, "TransactionTests/Homestead/tt10mbDataField"}
+declare_test!{heavy => TransactionTests_Homestead_tt10mbDataField, "TransactionTests/Homestead/tt10mbDataField"}
 declare_test!{TransactionTests_Homestead_ttWrongRLPTransaction, "TransactionTests/Homestead/ttWrongRLPTransaction"}
 declare_test!{TransactionTests_RandomTests_tr201506052141PYTHON, "TransactionTests/RandomTests/tr201506052141PYTHON"}
--- a/src/transaction.rs
+++ b/src/transaction.rs
@@ -117,9 +117,8 @@ impl Transaction {
 		};
 		s.append(&self.value);
 		s.append(&self.data);
-		match with_seal {
-			Seal::With => { s.append(&(self.v as u16)).append(&self.r).append(&self.s); },
-			_ => {}
+		if let Seal::With = with_seal {
+			s.append(&(self.v as u16)).append(&self.r).append(&self.s);
 		}
 	}

@@ -138,7 +137,7 @@ impl FromJson for Transaction {
 			gas_price: xjson!(&json["gasPrice"]),
 			gas: xjson!(&json["gasLimit"]),
 			action: match Bytes::from_json(&json["to"]) {
-				ref x if x.len() == 0 => Action::Create,
+				ref x if x.is_empty() => Action::Create,
 				ref x => Action::Call(Address::from_slice(x)),
 			},
 			value: xjson!(&json["value"]),
@@ -303,4 +302,4 @@ fn signing() {
 	let key = KeyPair::create().unwrap();
 	let t = Transaction::new_create(U256::from(42u64), b"Hello!".to_vec(), U256::from(3000u64), U256::from(50_000u64), U256::from(1u64)).signed(&key.secret());
 	assert_eq!(Address::from(key.public().sha3()), t.sender().unwrap());
-}
+}
--- a/src/verification.rs
+++ b/src/verification.rs
@@ -64,7 +64,7 @@ pub fn verify_block_unordered(header: Header, bytes: Bytes, engine: &Engine) ->
 /// Phase 3 verification. Check block information against parent and uncles.
 pub fn verify_block_family<BC>(header: &Header, bytes: &[u8], engine: &Engine, bc: &BC) -> Result<(), Error> where BC: BlockProvider {
 	// TODO: verify timestamp
-	let parent = try!(bc.block_header(&header.parent_hash).ok_or::<Error>(From::from(BlockError::UnknownParent(header.parent_hash.clone()))));
+	let parent = try!(bc.block_header(&header.parent_hash).ok_or_else(|| Error::from(BlockError::UnknownParent(header.parent_hash.clone()))));
 	try!(verify_parent(&header, &parent));
 	try!(engine.verify_block_family(&header, &parent, Some(bytes)));

@@ -122,7 +122,7 @@ pub fn verify_block_family<BC>(header: &Header, bytes: &[u8], engine: &Engine, b
 			// cB.p^7	-------------/
 			// cB.p^8
 			let mut expected_uncle_parent = header.parent_hash.clone();
-			let uncle_parent = try!(bc.block_header(&uncle.parent_hash).ok_or::<Error>(From::from(BlockError::UnknownUncleParent(uncle.parent_hash.clone()))));
+			let uncle_parent = try!(bc.block_header(&uncle.parent_hash).ok_or_else(|| Error::from(BlockError::UnknownUncleParent(uncle.parent_hash.clone()))));
 			for _ in 0..depth {
 				match bc.block_details(&expected_uncle_parent) {
 					Some(details) => { 
@@ -284,7 +284,7 @@ mod tests {

 		/// Get raw block data
 		fn block(&self, hash: &H256) -> Option<Bytes> {
-			self.blocks.get(hash).map(|b| b.clone())
+			self.blocks.get(hash).cloned()
 		}

 		/// Get the familial details concerning a block.
@@ -302,7 +302,7 @@ mod tests {

 		/// Get the hash of given block's number.
 		fn block_hash(&self, index: BlockNumber) -> Option<H256> {
-			self.numbers.get(&index).map(|h| h.clone())
+			self.numbers.get(&index).cloned()
 		}
 	}

--- a/src/views.rs
+++ b/src/views.rs
@@ -141,7 +141,7 @@ impl<'a> BlockView<'a> {

 	/// Return List of transactions in given block.
 	pub fn transaction_views(&self) -> Vec<TransactionView> {
-		self.rlp.at(1).iter().map(|rlp| TransactionView::new_from_rlp(rlp)).collect()
+		self.rlp.at(1).iter().map(TransactionView::new_from_rlp).collect()
 	}

 	/// Return transaction hashes.
@@ -156,7 +156,7 @@ impl<'a> BlockView<'a> {

 	/// Return List of transactions in given block.
 	pub fn uncle_views(&self) -> Vec<HeaderView> {
-		self.rlp.at(2).iter().map(|rlp| HeaderView::new_from_rlp(rlp)).collect()
+		self.rlp.at(2).iter().map(HeaderView::new_from_rlp).collect()
 	}

 	/// Return list of uncle hashes of given block.