Merge branch 'master' of github.com:ethcore/parity into db_writer

ethcore/src/client/client.rs

@@ -122,7 +122,7 @@ const CLIENT_DB_VER_STR: &'static str = "5.3";
 
 impl Client<CanonVerifier> {
 	/// Create a new client with given spec and DB path.
-	pub fn new(config: ClientConfig, spec: Spec, path: &Path, message_channel: IoChannel<NetSyncMessage> ) -> Result<Arc<Client>, Error> {
+	pub fn new(config: ClientConfig, spec: Spec, path: &Path, message_channel: IoChannel<NetSyncMessage> ) -> Arc<Client> {
 		Client::<CanonVerifier>::new_with_verifier(config, spec, path, message_channel)
 	}
 }
@@ -146,7 +146,7 @@ pub fn append_path(path: &Path, item: &str) -> String {
 
 impl<V> Client<V> where V: Verifier {
 	///  Create a new client with given spec and DB path and custom verifier.
-	pub fn new_with_verifier(config: ClientConfig, spec: Spec, path: &Path, message_channel: IoChannel<NetSyncMessage> ) -> Result<Arc<Client<V>>, Error> {
+	pub fn new_with_verifier(config: ClientConfig, spec: Spec, path: &Path, message_channel: IoChannel<NetSyncMessage> ) -> Arc<Client<V>> {
 		let path = get_db_path(path, config.pruning, spec.genesis_header().hash());
 		let gb = spec.genesis_block();
 		let chain = Arc::new(BlockChain::new(config.blockchain, &gb, &path));
@@ -163,7 +163,7 @@ impl<V> Client<V> where V: Verifier {
 		let panic_handler = PanicHandler::new_in_arc();
 		panic_handler.forward_from(&block_queue);
 
-		Ok(Arc::new(Client {
+		Arc::new(Client {
 			chain: chain,
 			engine: engine,
 			state_db: Mutex::new(state_db),
@@ -172,7 +172,7 @@ impl<V> Client<V> where V: Verifier {
 			import_lock: Mutex::new(()),
 			panic_handler: panic_handler,
 			verifier: PhantomData,
-		}))
+		})
 	}
 
 	/// Flush the block import queue.

ethcore/src/error.rs

@@ -62,13 +62,18 @@ pub enum ExecutionError {
 	Internal
 }
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq)]
 /// Errors concerning transaction processing.
 pub enum TransactionError {
 	/// Transaction is already imported to the queue
 	AlreadyImported,
 	/// Transaction is not valid anymore (state already has higher nonce)
 	Old,
+	/// Transaction has too low fee
+	/// (there is already a transaction with the same sender-nonce but higher gas price)
+	TooCheapToReplace,
+	/// Transaction was not imported to the queue because limit has been reached.
+	LimitReached,
 	/// Transaction's gas price is below threshold.
 	InsufficientGasPrice {
 		/// Minimal expected gas price
@@ -153,7 +158,7 @@ pub enum BlockError {
 	UnknownUncleParent(H256),
 }
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq)]
 /// Import to the block queue result
 pub enum ImportError {
 	/// Already in the block chain.

ethcore/src/json_tests/chain.rs

@@ -53,7 +53,7 @@ pub fn json_chain_test(json_data: &[u8], era: ChainEra) -> Vec<String> {
 
 			let temp = RandomTempPath::new();
 			{
-				let client = Client::new(ClientConfig::default(), spec, temp.as_path(), IoChannel::disconnected()).unwrap();
+				let client = Client::new(ClientConfig::default(), spec, temp.as_path(), IoChannel::disconnected());
 				for b in &blockchain.blocks_rlp() {
 					if Block::is_good(&b) {
 						let _ = client.import_block(b.clone());

ethcore/src/json_tests/executive.rs

@@ -17,11 +17,9 @@
 use super::test_common::*;
 use state::*;
 use executive::*;
-use spec::*;
 use engine::*;
 use evm;
 use evm::{Schedule, Ext, Factory, VMType, ContractCreateResult, MessageCallResult};
-use ethereum;
 use externalities::*;
 use substate::*;
 use tests::helpers::*;

ethcore/src/service.rs

@@ -61,7 +61,7 @@ impl ClientService {
 
 		info!("Starting {}", net_service.host_info());
 		info!("Configured for {} using {:?} engine", spec.name, spec.engine.name());
-		let client = try!(Client::new(config, spec, db_path, net_service.io().channel()));
+		let client = Client::new(config, spec, db_path, net_service.io().channel());
 		panic_handler.forward_from(client.deref());
 		let client_io = Arc::new(ClientIoHandler {
 			client: client.clone()

ethcore/src/tests/client.rs

@@ -20,17 +20,10 @@ use tests::helpers::*;
 use common::*;
 use devtools::*;
 
-#[test]
-fn created() {
-	let dir = RandomTempPath::new();
-	let client_result = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected());
-	assert!(client_result.is_ok());
-}
-
 #[test]
 fn imports_from_empty() {
 	let dir = RandomTempPath::new();
-	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
+	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected());
 	client.import_verified_blocks(&IoChannel::disconnected());
 	client.flush_queue();
 }
@@ -48,7 +41,7 @@ fn returns_state_root_basic() {
 #[test]
 fn imports_good_block() {
 	let dir = RandomTempPath::new();
-	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
+	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected());
 	let good_block = get_good_dummy_block();
 	if let Err(_) = client.import_block(good_block) {
 		panic!("error importing block being good by definition");
@@ -63,7 +56,7 @@ fn imports_good_block() {
 #[test]
 fn query_none_block() {
 	let dir = RandomTempPath::new();
-	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
+	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected());
 
     let non_existant = client.block_header(BlockId::Number(188));
 	assert!(non_existant.is_none());

ethcore/src/tests/helpers.rs

@@ -145,7 +145,7 @@ pub fn create_test_block_with_data(header: &Header, transactions: &[&SignedTrans
 pub fn generate_dummy_client(block_number: u32) -> GuardedTempResult<Arc<Client>> {
 	let dir = RandomTempPath::new();
 
-	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
+	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected());
 	let test_spec = get_test_spec();
 	let test_engine = &test_spec.engine;
 	let state_root = test_spec.genesis_header().state_root;
@@ -211,7 +211,7 @@ pub fn push_blocks_to_client(client: &Arc<Client>, timestamp_salt: u64, starting
 
 pub fn get_test_client_with_blocks(blocks: Vec<Bytes>) -> GuardedTempResult<Arc<Client>> {
 	let dir = RandomTempPath::new();
-	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
+	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected());
 	for block in &blocks {
 		if let Err(_) = client.import_block(block.clone()) {
 			panic!("panic importing block which is well-formed");

miner/src/lib.rs

@@ -38,7 +38,7 @@
 //! fn main() {
 //! 	let mut service = NetworkService::start(NetworkConfiguration::new()).unwrap();
 //! 	let dir = env::temp_dir();
-//! 	let client = Client::new(ClientConfig::default(), ethereum::new_frontier(), &dir, service.io().channel()).unwrap();
+//! 	let client = Client::new(ClientConfig::default(), ethereum::new_frontier(), &dir, service.io().channel());
 //!
 //!		let miner: Miner = Miner::default();
 //!		// get status
@@ -61,7 +61,7 @@ extern crate rayon;
 mod miner;
 mod transaction_queue;
 
-pub use transaction_queue::{TransactionQueue, AccountDetails};
+pub use transaction_queue::{TransactionQueue, AccountDetails, TransactionImportResult};
 pub use miner::{Miner};
 
 use util::{H256, U256, Address, Bytes};
@@ -100,6 +100,12 @@ pub trait MinerService : Send + Sync {
 	/// Set the gas limit we wish to target when sealing a new block.
 	fn set_gas_floor_target(&self, target: U256);
 
+	/// Get current transactions limit in queue.
+	fn transactions_limit(&self) -> usize;
+
+	/// Set maximal number of transactions kept in the queue (both current and future).
+	fn set_transactions_limit(&self, limit: usize);
+
 	/// Imports transactions to transaction queue.
 	fn import_transactions<T>(&self, transactions: Vec<SignedTransaction>, fetch_account: T) ->
 		Vec<Result<TransactionImportResult, Error>>
@@ -145,15 +151,6 @@ pub trait MinerService : Send + Sync {
 	fn sensible_gas_limit(&self) -> U256 { x!(21000) }
 }
 
-/// Represents the result of importing transaction.
-#[derive(Debug)]
-pub enum TransactionImportResult {
-	/// Transaction was imported to current queue.
-	Current,
-	/// Transaction was imported to future queue.
-	Future
-}
-
 /// Mining status
 #[derive(Debug)]
 pub struct MinerStatus {

miner/src/miner.rs

@@ -205,6 +205,14 @@ impl MinerService for Miner {
 		*self.gas_floor_target.read().unwrap() / x!(5)
 	}
 
+	fn transactions_limit(&self) -> usize {
+		self.transaction_queue.lock().unwrap().limit()
+	}
+
+	fn set_transactions_limit(&self, limit: usize) {
+		self.transaction_queue.lock().unwrap().set_limit(limit)
+	}
+
 	/// Get the author that we will seal blocks as.
 	fn author(&self) -> Address {
 		*self.author.read().unwrap()

miner/src/transaction_queue.rs

@@ -86,14 +86,13 @@
 
 use std::default::Default;
 use std::cmp::{Ordering};
+use std::cmp;
 use std::collections::{HashMap, BTreeSet};
 use util::numbers::{Uint, U256};
 use util::hash::{Address, H256};
 use util::table::*;
 use ethcore::transaction::*;
 use ethcore::error::{Error, TransactionError};
-use super::TransactionImportResult;
-
 
 #[derive(Clone, Debug)]
 /// Light structure used to identify transaction and it's order
@@ -206,10 +205,11 @@ impl TransactionSet {
 	/// Remove low priority transactions if there is more then specified by given `limit`.
 	///
 	/// It drops transactions from this set but also removes associated `VerifiedTransaction`.
-	fn enforce_limit(&mut self, by_hash: &mut HashMap<H256, VerifiedTransaction>) {
+	/// Returns addresses and highes nonces of transactions removed because of limit.
+	fn enforce_limit(&mut self, by_hash: &mut HashMap<H256, VerifiedTransaction>) -> Option<HashMap<Address, U256>> {
 		let len = self.by_priority.len();
 		if len <= self.limit {
-			return;
+			return None;
 		}
 
 		let to_drop : Vec<(Address, U256)> = {
@@ -222,10 +222,18 @@ impl TransactionSet {
 				.collect()
 		};
 
-		for (sender, nonce) in to_drop {
-			let order = self.drop(&sender, &nonce).expect("Transaction has just been found in `by_priority`; so it is in `by_address` also.");
-			by_hash.remove(&order.hash).expect("Hash found in `by_priorty` matches the one dropped; so it is included in `by_hash`");
-		}
+		Some(to_drop.into_iter()
+			.fold(HashMap::new(), |mut removed, (sender, nonce)| {
+				let order = self.drop(&sender, &nonce)
+					.expect("Transaction has just been found in `by_priority`; so it is in `by_address` also.");
+
+				by_hash.remove(&order.hash)
+					.expect("Hash found in `by_priorty` matches the one dropped; so it is included in `by_hash`");
+
+				let max = removed.get(&sender).map(|val| cmp::max(*val, nonce)).unwrap_or(nonce);
+				removed.insert(sender, max);
+				removed
+			}))
 	}
 
 	/// Drop transaction from this set (remove from `by_priority` and `by_address`)
@@ -242,6 +250,12 @@ impl TransactionSet {
 		self.by_priority.clear();
 		self.by_address.clear();
 	}
+
+	/// Sets new limit for number of transactions in this `TransactionSet`.
+	/// Note the limit is not applied (no transactions are removed) by calling this method.
+	fn set_limit(&mut self, limit: usize) {
+		self.limit = limit;
+	}
 }
 
 #[derive(Debug)]
@@ -253,6 +267,15 @@ pub struct TransactionQueueStatus {
 	pub future: usize,
 }
 
+#[derive(Debug, PartialEq)]
+/// Represents the result of importing transaction.
+pub enum TransactionImportResult {
+	/// Transaction was imported to current queue.
+	Current,
+	/// Transaction was imported to future queue.
+	Future
+}
+
 /// Details of account
 pub struct AccountDetails {
 	/// Most recent account nonce
@@ -290,20 +313,21 @@ impl Default for TransactionQueue {
 impl TransactionQueue {
 	/// Creates new instance of this Queue
 	pub fn new() -> Self {
-		Self::with_limits(1024, 1024)
+		Self::with_limit(1024)
 	}
 
 	/// Create new instance of this Queue with specified limits
-	pub fn with_limits(current_limit: usize, future_limit: usize) -> Self {
+	pub fn with_limit(limit: usize) -> Self {
 		let current = TransactionSet {
 			by_priority: BTreeSet::new(),
 			by_address: Table::new(),
-			limit: current_limit,
+			limit: limit,
 		};
+
 		let future = TransactionSet {
 			by_priority: BTreeSet::new(),
 			by_address: Table::new(),
-			limit: future_limit,
+			limit: limit,
 		};
 
 		TransactionQueue {
@@ -316,6 +340,20 @@ impl TransactionQueue {
 		}
 	}
 
+	/// Set the new limit for `current` and `future` queue.
+	pub fn set_limit(&mut self, limit: usize) {
+		self.current.set_limit(limit);
+		self.future.set_limit(limit);
+		// And ensure the limits
+		self.current.enforce_limit(&mut self.by_hash);
+		self.future.enforce_limit(&mut self.by_hash);
+	}
+
+	/// Returns current limit of transactions in the queue.
+	pub fn limit(&self) -> usize {
+		self.current.limit
+	}
+
 	/// Get the minimal gas price.
 	pub fn minimal_gas_price(&self) -> &U256 {
 		&self.minimal_gas_price
@@ -589,8 +627,8 @@ impl TransactionQueue {
 		// Check height
 		if nonce > next_nonce {
 			// We have a gap - put to future
-			Self::replace_transaction(tx, next_nonce, &mut self.future, &mut self.by_hash);
-			self.future.enforce_limit(&mut self.by_hash);
+			try!(check_too_cheap(Self::replace_transaction(tx, next_nonce, &mut self.future, &mut self.by_hash)));
+			try!(check_if_removed(&address, &nonce, self.future.enforce_limit(&mut self.by_hash)));
 			return Ok(TransactionImportResult::Future);
 		} else if nonce < state_nonce {
 			// Droping transaction
@@ -598,7 +636,7 @@ impl TransactionQueue {
 			return Err(TransactionError::Old);
 		}
 
-		Self::replace_transaction(tx, state_nonce, &mut self.current, &mut self.by_hash);
+		try!(check_too_cheap(Self::replace_transaction(tx, state_nonce, &mut self.current, &mut self.by_hash)));
 		// Keep track of highest nonce stored in current
 		self.last_nonces.insert(address, nonce);
 		// Update nonces of transactions in future
@@ -610,26 +648,48 @@ impl TransactionQueue {
 		if let Some(order) = self.future.drop(&address, &nonce) {
 			// Let's insert that transaction to current (if it has higher gas_price)
 			let future_tx = self.by_hash.remove(&order.hash).unwrap();
-			Self::replace_transaction(future_tx, state_nonce, &mut self.current, &mut self.by_hash);
+			try!(check_too_cheap(Self::replace_transaction(future_tx, state_nonce, &mut self.current, &mut self.by_hash)));
 		}
+
 		// Also enforce the limit
-		self.current.enforce_limit(&mut self.by_hash);
+		let removed = self.current.enforce_limit(&mut self.by_hash);
+		// If some transaction were removed because of limit we need to update last_nonces also.
+		self.update_last_nonces(&removed);
+		// Trigger error if we were removed.
+		try!(check_if_removed(&address, &nonce, removed));
 
 		trace!(target: "miner", "status: {:?}", self.status());
 		Ok(TransactionImportResult::Current)
 	}
 
+	/// Updates
+	fn update_last_nonces(&mut self, removed_max_nonces: &Option<HashMap<Address, U256>>) {
+		if let Some(ref max_nonces) = *removed_max_nonces {
+			for (sender, nonce) in max_nonces.iter() {
+				if *nonce == U256::zero() {
+					self.last_nonces.remove(sender);
+				} else {
+					self.last_nonces.insert(*sender, *nonce - U256::one());
+				}
+			}
+		}
+	}
+
 	/// Replaces transaction in given set (could be `future` or `current`).
 	///
 	/// If there is already transaction with same `(sender, nonce)` it will be replaced iff `gas_price` is higher.
 	/// One of the transactions is dropped from set and also removed from queue entirely (from `by_hash`).
-	fn replace_transaction(tx: VerifiedTransaction, base_nonce: U256, set: &mut TransactionSet, by_hash: &mut HashMap<H256, VerifiedTransaction>) {
+	///
+	/// Returns `true` if transaction actually got to the queue (`false` if there was already a transaction with higher
+	/// gas_price)
+	fn replace_transaction(tx: VerifiedTransaction, base_nonce: U256, set: &mut TransactionSet, by_hash: &mut HashMap<H256, VerifiedTransaction>) -> bool {
 		let order = TransactionOrder::for_transaction(&tx, base_nonce);
 		let hash = tx.hash();
 		let address = tx.sender();
 		let nonce = tx.nonce();
 
 		by_hash.insert(hash, tx);
+
 		if let Some(old) = set.insert(address, nonce, order.clone()) {
 			// There was already transaction in queue. Let's check which one should stay
 			let old_fee = old.gas_price;
@@ -639,12 +699,36 @@ impl TransactionQueue {
 				set.insert(address, nonce, old);
 				// and remove new one
 				by_hash.remove(&hash);
+				false
 			} else {
 				// Make sure we remove old transaction entirely
 				by_hash.remove(&old.hash);
+				true
+			}
+		} else {
+			true
 		}
 	}
 }
+
+fn check_too_cheap(is_in: bool) -> Result<(), TransactionError> {
+	if !is_in {
+		Err(TransactionError::TooCheapToReplace)
+	} else {
+		Ok(())
+	}
+}
+
+fn check_if_removed(sender: &Address, nonce: &U256, dropped: Option<HashMap<Address, U256>>) -> Result<(), TransactionError> {
+	match dropped {
+		Some(ref dropped) => match dropped.get(sender) {
+			Some(max) if nonce <= max => {
+				Err(TransactionError::LimitReached)
+			},
+			_ => Ok(()),
+		},
+		_ => Ok(()),
+	}
 }
 
 
@@ -654,9 +738,17 @@ mod test {
 	use util::table::*;
 	use util::*;
 	use ethcore::transaction::*;
+	use ethcore::error::{Error, TransactionError};
 	use super::*;
 	use super::{TransactionSet, TransactionOrder, VerifiedTransaction};
 
+	fn unwrap_tx_err(err: Result<TransactionImportResult, Error>) -> TransactionError {
+		match err.unwrap_err() {
+			Error::Transaction(e) => e,
+			_ => panic!("Expected transaction error!"),
+		}
+	}
+
 	fn new_unsigned_tx(nonce: U256) -> Transaction {
 		Transaction {
 			action: Action::Create,
@@ -698,11 +790,16 @@ mod test {
 	}
 
 	fn new_txs(second_nonce: U256) -> (SignedTransaction, SignedTransaction) {
+		new_txs_with_gas_price_diff(second_nonce, U256::zero())
+	}
+
+	fn new_txs_with_gas_price_diff(second_nonce: U256, gas_price: U256) -> (SignedTransaction, SignedTransaction) {
 		let keypair = KeyPair::create().unwrap();
 		let secret = &keypair.secret();
 		let nonce = U256::from(123);
 		let tx = new_unsigned_tx(nonce);
-		let tx2 = new_unsigned_tx(nonce + second_nonce);
+		let mut tx2 = new_unsigned_tx(nonce + second_nonce);
+		tx2.gas_price = tx2.gas_price + gas_price;
 
 		(tx.sign(secret), tx2.sign(secret))
 	}
@@ -795,14 +892,14 @@ mod test {
 
 		// First insert one transaction to future
 		let res = txq.add(tx, &prev_nonce);
-		assert!(res.is_ok());
+		assert_eq!(res.unwrap(), TransactionImportResult::Future);
 		assert_eq!(txq.status().future, 1);
 
 		// now import second transaction to current
 		let res = txq.add(tx2.clone(), &default_nonce);
 
 		// and then there should be only one transaction in current (the one with higher gas_price)
-		assert!(res.is_ok());
+		assert_eq!(unwrap_tx_err(res), TransactionError::TooCheapToReplace);
 		assert_eq!(txq.status().pending, 1);
 		assert_eq!(txq.status().future, 0);
 		assert_eq!(txq.current.by_priority.len(), 1);
@@ -821,7 +918,7 @@ mod test {
 		let res = txq.add(tx, &default_nonce);
 
 		// then
-		assert!(res.is_ok());
+		assert_eq!(res.unwrap(), TransactionImportResult::Current);
 		let stats = txq.status();
 		assert_eq!(stats.pending, 1);
 	}
@@ -845,12 +942,18 @@ mod test {
 		// given
 		let mut txq = TransactionQueue::new();
 		let tx = new_tx();
-		txq.set_gas_limit(tx.gas / U256::from(2));
+		let gas = tx.gas;
+		let limit = gas / U256::from(2);
+		txq.set_gas_limit(limit);
 
 		// when
-		txq.add(tx, &default_nonce).unwrap_err();
+		let res = txq.add(tx, &default_nonce);
 
 		// then
+		assert_eq!(unwrap_tx_err(res), TransactionError::GasLimitExceeded {
+			limit: U256::from(55_000), // Should be 110% of set_gas_limit
+			got: gas,
+		});
 		let stats = txq.status();
 		assert_eq!(stats.pending, 0);
 		assert_eq!(stats.future, 0);
@@ -868,9 +971,13 @@ mod test {
 		};
 
 		// when
-		txq.add(tx, &account).unwrap_err();
+		let res = txq.add(tx, &account);
 
 		// then
+		assert_eq!(unwrap_tx_err(res), TransactionError::InsufficientBalance {
+			balance: U256::from(1),
+			cost: U256::from(100_100),
+		});
 		let stats = txq.status();
 		assert_eq!(stats.pending, 0);
 		assert_eq!(stats.future, 0);
@@ -884,9 +991,13 @@ mod test {
 		txq.set_minimal_gas_price(tx.gas_price + U256::one());
 
 		// when
-		txq.add(tx, &default_nonce).unwrap_err();
+		let res = txq.add(tx, &default_nonce);
 
 		// then
+		assert_eq!(unwrap_tx_err(res), TransactionError::InsufficientGasPrice {
+			minimal: U256::from(2),
+			got: U256::from(1),
+		});
 		let stats = txq.status();
 		assert_eq!(stats.pending, 0);
 		assert_eq!(stats.future, 0);
@@ -961,10 +1072,12 @@ mod test {
 		let (tx, tx2) = new_txs(U256::from(2));
 
 		// when
-		txq.add(tx.clone(), &default_nonce).unwrap();
-		txq.add(tx2.clone(), &default_nonce).unwrap();
+		let res1 = txq.add(tx.clone(), &default_nonce).unwrap();
+		let res2 = txq.add(tx2.clone(), &default_nonce).unwrap();
 
 		// then
+		assert_eq!(res1, TransactionImportResult::Current);
+		assert_eq!(res2, TransactionImportResult::Future);
 		let stats = txq.status();
 		assert_eq!(stats.pending, 1);
 		assert_eq!(stats.future, 1);
@@ -1085,26 +1198,53 @@ mod test {
 	#[test]
 	fn should_drop_old_transactions_when_hitting_the_limit() {
 		// given
-		let mut txq = TransactionQueue::with_limits(1, 1);
+		let mut txq = TransactionQueue::with_limit(1);
 		let (tx, tx2) = new_txs(U256::one());
+		let sender = tx.sender().unwrap();
+		let nonce = tx.nonce;
 		txq.add(tx.clone(), &default_nonce).unwrap();
 		assert_eq!(txq.status().pending, 1);
 
 		// when
-		txq.add(tx2.clone(), &default_nonce).unwrap();
+		let res = txq.add(tx2.clone(), &default_nonce);
 
 		// then
 		let t = txq.top_transactions();
+		assert_eq!(unwrap_tx_err(res), TransactionError::LimitReached);
 		assert_eq!(txq.status().pending, 1);
 		assert_eq!(t.len(), 1);
 		assert_eq!(t[0], tx);
+		assert_eq!(txq.last_nonce(&sender), Some(nonce));
+	}
+
+	#[test]
+	fn should_return_correct_nonces_when_dropped_because_of_limit() {
+		// given
+		let mut txq = TransactionQueue::with_limit(2);
+		let tx = new_tx();
+		let (tx1, tx2) = new_txs(U256::one());
+		let sender = tx1.sender().unwrap();
+		let nonce = tx1.nonce;
+		txq.add(tx1.clone(), &default_nonce).unwrap();
+		txq.add(tx2.clone(), &default_nonce).unwrap();
+		assert_eq!(txq.status().pending, 2);
+		assert_eq!(txq.last_nonce(&sender), Some(nonce + U256::one()));
+
+		// when
+		let res = txq.add(tx.clone(), &default_nonce);
+
+		// then
+		assert_eq!(res.unwrap(), TransactionImportResult::Current);
+		assert_eq!(txq.status().pending, 2);
+		assert_eq!(txq.last_nonce(&sender), Some(nonce));
 	}
 
 	#[test]
 	fn should_limit_future_transactions() {
-		let mut txq = TransactionQueue::with_limits(10, 1);
-		let (tx1, tx2) = new_txs(U256::from(4));
-		let (tx3, tx4) = new_txs(U256::from(4));
+		let mut txq = TransactionQueue::with_limit(1);
+		txq.current.set_limit(10);
+		let (tx1, tx2) = new_txs_with_gas_price_diff(U256::from(4), U256::from(1));
+		let (tx3, tx4) = new_txs_with_gas_price_diff(U256::from(4), U256::from(2));
 		txq.add(tx1.clone(), &default_nonce).unwrap();
 		txq.add(tx3.clone(), &default_nonce).unwrap();
 		assert_eq!(txq.status().pending, 2);
@@ -1126,9 +1266,10 @@ mod test {
 		let fetch_last_nonce = |_a: &Address| AccountDetails{ nonce: last_nonce, balance: !U256::zero() };
 
 		// when
-		txq.add(tx, &fetch_last_nonce).unwrap_err();
+		let res = txq.add(tx, &fetch_last_nonce);
 
 		// then
+		assert_eq!(unwrap_tx_err(res), TransactionError::Old);
 		let stats = txq.status();
 		assert_eq!(stats.pending, 0);
 		assert_eq!(stats.future, 0);
@@ -1146,9 +1287,10 @@ mod test {
 		assert_eq!(txq.status().pending, 0);
 
 		// when
-		txq.add(tx2.clone(), &nonce).unwrap_err();
+		let res = txq.add(tx2.clone(), &nonce);
 
 		// then
+		assert_eq!(unwrap_tx_err(res), TransactionError::AlreadyImported);
 		let stats = txq.status();
 		assert_eq!(stats.future, 1);
 		assert_eq!(stats.pending, 0);

parity/main.rs

@@ -172,6 +172,8 @@ Sealing/Mining Options:
                            [default: 0037a6b811ffeb6e072da21179d11b1406371c63].
   --extra-data STRING      Specify a custom extra-data for authored blocks, no
                            more than 32 characters.
+  --tx-limit LIMIT         Limit of transactions kept in the queue (waiting to
+                           be included in next block) [default: 1024].
 
 Footprint Options:
   --pruning METHOD         Configure pruning of the state/storage trie. METHOD
@@ -259,6 +261,7 @@ struct Args {
 	flag_usd_per_eth: String,
 	flag_gas_floor_target: String,
 	flag_extra_data: Option<String>,
+	flag_tx_limit: usize,
 	flag_logging: Option<String>,
 	flag_version: bool,
 	// geth-compatibility...
@@ -713,6 +716,7 @@ impl Configuration {
 		miner.set_gas_floor_target(self.gas_floor_target());
 		miner.set_extra_data(self.extra_data());
 		miner.set_minimal_gas_price(self.gas_price());
+		miner.set_transactions_limit(self.args.flag_tx_limit);
 
 		// Sync
 		let sync = EthSync::register(service.network(), sync_config, client.clone(), miner.clone());

rpc/src/v1/impls/ethcore.rs

@@ -67,6 +67,17 @@ impl<M> Ethcore for EthcoreClient<M> where M: MinerService + 'static {
 		})
 	}
 
+	fn set_transactions_limit(&self, params: Params) -> Result<Value, Error> {
+		from_params::<(usize,)>(params).and_then(|(limit,)| {
+			take_weak!(self.miner).set_transactions_limit(limit);
+			to_value(&true)
+		})
+	}
+
+	fn transactions_limit(&self, _: Params) -> Result<Value, Error> {
+		to_value(&take_weak!(self.miner).transactions_limit())
+	}
+
 	fn min_gas_price(&self, _: Params) -> Result<Value, Error> {
 		to_value(&take_weak!(self.miner).minimal_gas_price())
 	}

rpc/src/v1/tests/ethcore.rs

@@ -123,3 +123,31 @@ fn rpc_ethcore_set_author() {
 	assert_eq!(io.handle_request(request), Some(response.to_owned()));
 	assert_eq!(miner.author(), Address::from_str("cd1722f3947def4cf144679da39c4c32bdc35681").unwrap());
 }
+
+#[test]
+fn rpc_ethcore_set_transactions_limit() {
+	let miner = miner_service();
+	let ethcore = EthcoreClient::new(&miner).to_delegate();
+	let io = IoHandler::new();
+	io.add_delegate(ethcore);
+
+	let request = r#"{"jsonrpc": "2.0", "method": "ethcore_setTransactionsLimit", "params":[10240240], "id": 1}"#;
+	let response = r#"{"jsonrpc":"2.0","result":true,"id":1}"#;
+
+	assert_eq!(io.handle_request(request), Some(response.to_owned()));
+	assert_eq!(miner.transactions_limit(), 10_240_240);
+}
+
+
+#[test]
+fn rpc_ethcore_transactions_limit() {
+	let miner = miner_service();
+	let ethcore = EthcoreClient::new(&miner).to_delegate();
+	let io = IoHandler::new();
+	io.add_delegate(ethcore);
+
+	let request = r#"{"jsonrpc": "2.0", "method": "ethcore_transactionsLimit", "params":[], "id": 1}"#;
+	let response = r#"{"jsonrpc":"2.0","result":1024,"id":1}"#;
+
+	assert_eq!(io.handle_request(request), Some(response.to_owned()));
+}

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

@@ -39,6 +39,7 @@ pub struct TestMinerService {
 	gas_floor_target: RwLock<U256>,
 	author: RwLock<Address>,
 	extra_data: RwLock<Bytes>,
+	limit: RwLock<usize>,
 }
 
 impl Default for TestMinerService {
@@ -52,6 +53,7 @@ impl Default for TestMinerService {
 			gas_floor_target: RwLock::new(U256::from(12345)),
 			author: RwLock::new(Address::zero()),
 			extra_data: RwLock::new(vec![1, 2, 3, 4]),
+			limit: RwLock::new(1024),
 		}
 	}
 }
@@ -84,6 +86,14 @@ impl MinerService for TestMinerService {
 		*self.min_gas_price.write().unwrap() = min_gas_price;
 	}
 
+	fn set_transactions_limit(&self, limit: usize) {
+		*self.limit.write().unwrap() = limit;
+	}
+
+	fn transactions_limit(&self) -> usize {
+		*self.limit.read().unwrap()
+	}
+
 	fn author(&self) -> Address {
 		*self.author.read().unwrap()
 	}

rpc/src/v1/traits/ethcore.rs

@@ -33,6 +33,12 @@ pub trait Ethcore: Sized + Send + Sync + 'static {
 	/// Sets new author for mined block.
 	fn set_author(&self, _: Params) -> Result<Value, Error> { rpc_unimplemented!() }
 
+	/// Sets the limits for transaction queue.
+	fn set_transactions_limit(&self, _: Params) -> Result<Value, Error> { rpc_unimplemented!() }
+
+	/// Returns current transactions limit.
+	fn transactions_limit(&self, _: Params) -> Result<Value, Error> { rpc_unimplemented!() }
+
 	/// Returns mining extra data.
 	fn extra_data(&self, _: Params) -> Result<Value, Error> { rpc_unimplemented!() }
 
@@ -49,10 +55,12 @@ pub trait Ethcore: Sized + Send + Sync + 'static {
 		delegate.add_method("ethcore_setGasFloorTarget", Ethcore::set_gas_floor_target);
 		delegate.add_method("ethcore_setExtraData", Ethcore::set_extra_data);
 		delegate.add_method("ethcore_setAuthor", Ethcore::set_author);
+		delegate.add_method("ethcore_setTransactionsLimit", Ethcore::set_transactions_limit);
 
 		delegate.add_method("ethcore_extraData", Ethcore::extra_data);
 		delegate.add_method("ethcore_gasFloorTarget", Ethcore::gas_floor_target);
 		delegate.add_method("ethcore_minGasPrice", Ethcore::min_gas_price);
+		delegate.add_method("ethcore_transactionsLimit", Ethcore::transactions_limit);
 		delegate
 	}
 }

sync/src/lib.rs

@@ -44,7 +44,7 @@
 //! fn main() {
 //! 	let mut service = NetworkService::start(NetworkConfiguration::new()).unwrap();
 //! 	let dir = env::temp_dir();
-//! 	let client = Client::new(ClientConfig::default(), ethereum::new_frontier(), &dir, service.io().channel()).unwrap();
+//! 	let client = Client::new(ClientConfig::default(), ethereum::new_frontier(), &dir, service.io().channel());
 //! 	let miner = Miner::new(false);
 //! 	EthSync::register(&mut service, SyncConfig::default(), client, miner);
 //! }