Merge branch 'master' into clippy

Conflicts:
	src/service.rs
	src/views.rs

Cargo.toml

@@ -19,6 +19,7 @@ time = "0.1"
 #interpolate_idents = { git = "https://github.com/SkylerLipthay/interpolate_idents" }
 evmjit = { path = "rust-evmjit", optional = true }
 ethash = { path = "ethash" }
+num_cpus = "0.2"
 
 [features]
 jit = ["evmjit"]

ethash/Cargo.toml

@@ -6,4 +6,4 @@ authors = ["arkpar <arkadiy@ethcore.io"]
 [lib]
 
 [dependencies]
-tiny-keccak = "1.0"
+sha3 = { path = "../util/sha3" }

ethash/src/compute.rs

@@ -6,7 +6,7 @@
 use std::mem;
 use std::ptr;
 use sizes::{CACHE_SIZES, DAG_SIZES};
-use tiny_keccak::Keccak;
+use sha3::{self};
 
 pub const ETHASH_EPOCH_LENGTH: u64 = 30000;
 pub const ETHASH_CACHE_ROUNDS: usize = 3;
@@ -85,9 +85,7 @@ fn fnv_hash(x: u32, y: u32) -> u32 {
 
 #[inline]
 fn sha3_512(input: &[u8], output: &mut [u8]) {
-		let mut sha3 = Keccak::new_keccak512();
+	unsafe { sha3::sha3_512(output.as_mut_ptr(), output.len(), input.as_ptr(), input.len()) };
-		sha3.update(input);
-		sha3.finalize(output);
 }
 
 #[inline]
@@ -107,9 +105,7 @@ fn get_seedhash(block_number: u64) -> H256 {
 	let epochs = block_number / ETHASH_EPOCH_LENGTH;
 	let mut ret: H256 = [0u8; 32];
 	for _ in 0..epochs {
-		let mut sha3 = Keccak::new_keccak256();
+		unsafe { sha3::sha3_256(ret[..].as_mut_ptr(), 32, ret[..].as_ptr(), 32) };
-		sha3.update(&ret);
-		sha3.finalize(&mut ret);
 	}
 	ret
 }
@@ -125,15 +121,12 @@ pub fn quick_get_difficulty(header_hash: &H256, nonce: u64, mix_hash: &H256) ->
 	unsafe { ptr::copy_nonoverlapping(header_hash.as_ptr(), buf.as_mut_ptr(), 32) };
 	unsafe { ptr::copy_nonoverlapping(mem::transmute(&nonce), buf[32..].as_mut_ptr(), 8) };
 
-	let mut sha3 = Keccak::new_keccak512();
+	unsafe { sha3::sha3_512(buf.as_mut_ptr(), 64, buf.as_ptr(), 40) };
-	sha3.update(&buf[0..40]);
-	sha3.finalize(&mut buf);
 	unsafe { ptr::copy_nonoverlapping(mix_hash.as_ptr(), buf[64..].as_mut_ptr(), 32) };
 
 	let mut hash = [0u8; 32];
-	let mut sha3 = Keccak::new_keccak256();
+	unsafe { sha3::sha3_256(hash.as_mut_ptr(), hash.len(), buf.as_ptr(), buf.len()) };
-	sha3.update(&buf);
+	hash.as_mut_ptr();
-	sha3.finalize(&mut hash);
 	hash
 }
 
@@ -157,10 +150,7 @@ fn hash_compute(light: &Light, full_size: usize,  header_hash: &H256, nonce: u64
 
 	// compute sha3-512 hash and replicate across mix
 	unsafe {
-		let mut sha3 = Keccak::new_keccak512();
+		sha3::sha3_512(s_mix.get_unchecked_mut(0).bytes.as_mut_ptr(), NODE_BYTES, s_mix.get_unchecked(0).bytes.as_ptr(), 40);
-		sha3.update(&s_mix.get_unchecked(0).bytes[0..40]);
-		sha3.finalize(&mut s_mix.get_unchecked_mut(0).bytes);
-
 		let (f_mix, mut mix) = s_mix.split_at_mut(1);
 		for w in 0..MIX_WORDS {
 			*mix.get_unchecked_mut(0).as_words_mut().get_unchecked_mut(w) = *f_mix.get_unchecked(0).as_words().get_unchecked(w % NODE_WORDS);
@@ -189,15 +179,13 @@ fn hash_compute(light: &Light, full_size: usize,  header_hash: &H256, nonce: u64
 			*mix.get_unchecked_mut(0).as_words_mut().get_unchecked_mut(i) = reduction;
 		}
 
-		let mut mix_hash: H256 = [0u8; 32];
+		let mut mix_hash = [0u8; 32];
+		let mut buf = [0u8; 32 + 64];
+		ptr::copy_nonoverlapping(f_mix.get_unchecked_mut(0).bytes.as_ptr(), buf.as_mut_ptr(), 64);
+		ptr::copy_nonoverlapping(mix.get_unchecked_mut(0).bytes.as_ptr(), buf[64..].as_mut_ptr(), 32);
 		ptr::copy_nonoverlapping(mix.get_unchecked_mut(0).bytes.as_ptr(), mix_hash.as_mut_ptr(), 32);
 		let mut value: H256 = [0u8; 32];
-
+		sha3::sha3_256(value.as_mut_ptr(), value.len(),  buf.as_ptr(), buf.len());
-		let mut sha3 = Keccak::new_keccak256();
-		sha3.update(&f_mix.get_unchecked(0).bytes);
-		sha3.update(&mix_hash);
-		sha3.finalize(&mut value);
-
 		ProofOfWork {
 			mix_hash: mix_hash,
 			value: value,
@@ -212,10 +200,7 @@ fn calculate_dag_item(node_index: u32, light: &Light) -> Node {
 		let init = cache_nodes.get_unchecked(node_index as usize % num_parent_nodes);
 		let mut ret = init.clone();
 		*ret.as_words_mut().get_unchecked_mut(0) ^= node_index;
-
+		sha3::sha3_512(ret.bytes.as_mut_ptr(), ret.bytes.len(), ret.bytes.as_ptr(), ret.bytes.len());
-		let mut sha3 = Keccak::new_keccak512();
-		sha3.update(&ret.bytes);
-		sha3.finalize(&mut ret.bytes);
 
 		for i in 0..ETHASH_DATASET_PARENTS {
 			let parent_index = fnv_hash(node_index ^ i, *ret.as_words().get_unchecked(i as usize % NODE_WORDS)) % num_parent_nodes as u32;
@@ -224,10 +209,7 @@ fn calculate_dag_item(node_index: u32, light: &Light) -> Node {
 				*ret.as_words_mut().get_unchecked_mut(w) = fnv_hash(*ret.as_words().get_unchecked(w), *parent.as_words().get_unchecked(w));
 			}
 		}
-
+		sha3::sha3_512(ret.bytes.as_mut_ptr(), ret.bytes.len(), ret.bytes.as_ptr(), ret.bytes.len());
-		let mut sha3 = Keccak::new_keccak512();
-		sha3.update(&ret.bytes);
-		sha3.finalize(&mut ret.bytes);
 		ret
 	}
 }
@@ -246,9 +228,7 @@ fn light_new(block_number: u64) -> Light {
 	unsafe {
 		sha3_512(&seedhash[0..32], &mut nodes.get_unchecked_mut(0).bytes);
 		for i in 1..num_nodes {
-			let mut sha3 = Keccak::new_keccak512();
+			sha3::sha3_512(nodes.get_unchecked_mut(i).bytes.as_mut_ptr(), NODE_BYTES, nodes.get_unchecked(i - 1).bytes.as_ptr(), NODE_BYTES);
-			sha3.update(&nodes.get_unchecked_mut(i - 1).bytes);
-			sha3.finalize(&mut nodes.get_unchecked_mut(i).bytes);
 		}
 		
 		for _ in 0..ETHASH_CACHE_ROUNDS {
@@ -275,9 +255,9 @@ fn test_difficulty_test() {
 	let mix_hash = [0x1f, 0xff, 0x04, 0xce, 0xc9, 0x41, 0x73, 0xfd, 0x59, 0x1e, 0x3d, 0x89, 0x60, 0xce, 0x6b, 0xdf, 0x8b, 0x19, 0x71, 0x04, 0x8c, 0x71, 0xff, 0x93, 0x7b, 0xb2, 0xd3, 0x2a, 0x64, 0x31, 0xab, 0x6d ]; 
 	let nonce = 0xd7b3ac70a301a249;
 	let boundary_good = [0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x3e, 0x9b, 0x6c, 0x69, 0xbc, 0x2c, 0xe2, 0xa2, 0x4a, 0x8e, 0x95, 0x69, 0xef, 0xc7, 0xd7, 0x1b, 0x33, 0x35, 0xdf, 0x36, 0x8c, 0x9a, 0xe9, 0x7e, 0x53, 0x84];
-	assert!(quick_check_difficulty(&hash, nonce, &mix_hash, &boundary_good));
+	assert_eq!(quick_get_difficulty(&hash, nonce, &mix_hash)[..], boundary_good[..]);
 	let boundary_bad = [0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x3a, 0x9b, 0x6c, 0x69, 0xbc, 0x2c, 0xe2, 0xa2, 0x4a, 0x8e, 0x95, 0x69, 0xef, 0xc7, 0xd7, 0x1b, 0x33, 0x35, 0xdf, 0x36, 0x8c, 0x9a, 0xe9, 0x7e, 0x53, 0x84];
-	assert!(!quick_check_difficulty(&hash, nonce, &mix_hash, &boundary_bad));
+	assert!(quick_get_difficulty(&hash, nonce, &mix_hash)[..] != boundary_bad[..]);
 }
 
 #[test]

ethash/src/lib.rs

@@ -1,6 +1,6 @@
 //! Ethash implementation
 //! See https://github.com/ethereum/wiki/wiki/Ethash
-extern crate tiny_keccak;
+extern crate sha3;
 mod sizes;
 mod compute;
 

src/block.rs

@@ -1,6 +1,7 @@
 use common::*;
 use engine::*;
 use state::*;
+use verification::PreVerifiedBlock;
 
 /// A transaction/receipt execution entry.
 pub struct Entry {
@@ -263,30 +264,39 @@ impl IsBlock for SealedBlock {
 	fn block(&self) -> &Block { &self.block }
 }
 
-/// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header
+/// Enact the block given by block header, transactions and uncles
-pub fn enact<'x, 'y>(block_bytes: &[u8], engine: &'x Engine, db: OverlayDB, parent: &Header, last_hashes: &'y LastHashes) -> Result<ClosedBlock<'x, 'y>, Error> {
+pub fn enact<'x, 'y>(header: &Header, transactions: &[Transaction], uncles: &[Header], engine: &'x Engine, db: OverlayDB, parent: &Header, last_hashes: &'y LastHashes) -> Result<ClosedBlock<'x, 'y>, Error> {
 	{
-		let header = BlockView::new(block_bytes).header_view();
 		let s = State::from_existing(db.clone(), parent.state_root().clone(), engine.account_start_nonce());
 		trace!("enact(): root={}, author={}, author_balance={}\n", s.root(), header.author(), s.balance(&header.author()));
 	}
 
-	let block = BlockView::new(block_bytes);
+	let mut b = OpenBlock::new(engine, db, parent, last_hashes, header.author().clone(), header.extra_data().clone());
-	let header = block.header_view();
+	b.set_difficulty(*header.difficulty());
-	let mut b = OpenBlock::new(engine, db, parent, last_hashes, header.author(), header.extra_data());
+	b.set_gas_limit(*header.gas_limit());
-	b.set_difficulty(header.difficulty());
-	b.set_gas_limit(header.gas_limit());
 	b.set_timestamp(header.timestamp());
-//	info!("enact: Enacting #{}. env_info={:?}", header.number(), b.env_info());
+	for t in transactions { try!(b.push_transaction(t.clone(), None)); }
-	for t in block.transactions().into_iter() { try!(b.push_transaction(t, None)); }
+	for u in uncles { try!(b.push_uncle(u.clone())); }
-	for u in block.uncles().into_iter() { try!(b.push_uncle(u)); }
 	Ok(b.close())
 }
 
+/// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header
+pub fn enact_bytes<'x, 'y>(block_bytes: &[u8], engine: &'x Engine, db: OverlayDB, parent: &Header, last_hashes: &'y LastHashes) -> Result<ClosedBlock<'x, 'y>, Error> {
+	let block = BlockView::new(block_bytes);
+	let header = block.header();
+	enact(&header, &block.transactions(), &block.uncles(), engine, db, parent, last_hashes)
+}
+
+/// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header
+pub fn enact_verified<'x, 'y>(block: &PreVerifiedBlock, engine: &'x Engine, db: OverlayDB, parent: &Header, last_hashes: &'y LastHashes) -> Result<ClosedBlock<'x, 'y>, Error> {
+	let view = BlockView::new(&block.bytes);
+	enact(&block.header, &block.transactions, &view.uncles(), engine, db, parent, last_hashes)
+}
+
 /// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header. Seal the block aferwards
 pub fn enact_and_seal(block_bytes: &[u8], engine: &Engine, db: OverlayDB, parent: &Header, last_hashes: &LastHashes) -> Result<SealedBlock, Error> {
 	let header = BlockView::new(block_bytes).header_view();
-	Ok(try!(try!(enact(block_bytes, engine, db, parent, last_hashes)).seal(header.seal())))
+	Ok(try!(try!(enact_bytes(block_bytes, engine, db, parent, last_hashes)).seal(header.seal())))
 }
 
 #[test]

src/client.rs

@@ -88,7 +88,7 @@ pub trait BlockChainClient : Sync + Send {
 	fn block_receipts(&self, hash: &H256) -> Option<Bytes>;
 
 	/// Import a block into the blockchain.
-	fn import_block(&mut self, byte: &[u8]) -> ImportResult;
+	fn import_block(&mut self, bytes: Bytes) -> ImportResult;
 
 	/// Get block queue information.
 	fn queue_status(&self) -> BlockQueueStatus;
@@ -152,12 +152,26 @@ impl Client {
 	}
 
 	/// This is triggered by a message coming from a block queue when the block is ready for insertion
-	pub fn import_verified_block(&mut self, bytes: Bytes) {
+	pub fn import_verified_blocks(&mut self) {
-		let block = BlockView::new(&bytes);
+		
-		let header = block.header();
+		let mut bad = HashSet::new();
-		if let Err(e) = verify_block_family(&header, &bytes, self.engine.deref().deref(), self.chain.read().unwrap().deref()) {
+		let blocks = self.queue.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());
+				bad.insert(block.header.hash());
+				continue;
+			}
+
+			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());
+				bad.insert(block.header.hash());
 				return;
 			};
 			let parent = match self.chain.read().unwrap().block_header(&header.parent_hash) {
@@ -165,6 +179,7 @@ impl Client {
 				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());
+					bad.insert(block.header.hash());
 					return;
 				},
 			};
@@ -181,10 +196,11 @@ impl Client {
 				}
 			}
 
-		let result = match enact(&bytes, self.engine.deref().deref(), self.state_db.clone(), &parent, &last_hashes) {
+			let result = match enact_verified(&block, self.engine.deref().deref(), self.state_db.clone(), &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());
 					return;
 				}
@@ -195,7 +211,7 @@ impl Client {
 				return;
 			}
 
-		self.chain.write().unwrap().insert_block(&bytes); //TODO: err here?
+			self.chain.write().unwrap().insert_block(&block.bytes); //TODO: err here?
 			match result.drain().commit() {
 				Ok(_) => (),
 				Err(e) => {
@@ -206,6 +222,7 @@ impl Client {
 			info!(target: "client", "Imported #{} ({})", header.number(), header.hash());
 		}
 	}
+}
 
 impl BlockChainClient for Client {
 	fn block_header(&self, hash: &H256) -> Option<Bytes> {
@@ -261,8 +278,8 @@ impl BlockChainClient for Client {
 		unimplemented!();
 	}
 
-	fn import_block(&mut self, bytes: &[u8]) -> ImportResult {
+	fn import_block(&mut self, bytes: Bytes) -> ImportResult {
-		let header = BlockView::new(bytes).header();
+		let header = BlockView::new(&bytes).header();
 		if self.chain.read().unwrap().is_known(&header.hash()) {
 			return Err(ImportError::AlreadyInChain);
 		}

src/ethereum/ethash.rs

@@ -146,6 +146,10 @@ impl Engine for Ethash {
 		}
 		Ok(())
 	}
+
+	fn verify_transaction(&self, t: &Transaction, _header: &Header) -> Result<(), Error> {
+		t.sender().map(|_|()) // Perform EC recovery and cache sender
+	}
 }
 
 impl Ethash {

src/evm/interpreter.rs

@@ -27,6 +27,14 @@ fn color(instruction: Instruction, name: &'static str) -> String {
 	format!("\x1B[1;{}m{}\x1B[0m", colors[c], name)
 }
 
+macro_rules! overflowing {
+	($x: expr) => {{
+		let (v, overflow) = $x;
+		if overflow { return Err(evm::Error::OutOfGas); }
+		v
+	}}
+}
+
 type CodePosition = usize;
 type Gas = U256;
 type ProgramCounter = usize;
@@ -136,7 +144,7 @@ trait Memory {
 /// Checks whether offset and size is valid memory range
 fn is_valid_range(off: usize, size: usize)  -> bool {
 	// When size is zero we haven't actually expanded the memory
-	let (_a, overflow) = off.overflowing_add(size);
+	let overflow = off.overflowing_add(size).1;
 	size > 0 && !overflow
 }
 
@@ -235,15 +243,10 @@ impl<'a> CodeReader<'a> {
 	}
 }
 
-enum RequiredMem {
-	Mem(U256),
-	OutOfMemory
-}
-
 enum InstructionCost {
 	Gas(U256),
-	GasMem(U256, RequiredMem),
+	GasMem(U256, U256),
-	GasMemCopy(U256, RequiredMem, U256)
+	GasMemCopy(U256, U256, U256)
 }
 
 enum InstructionResult {
@@ -373,35 +376,31 @@ impl Interpreter {
 				InstructionCost::Gas(U256::from(schedule.sload_gas))
 			},
 			instructions::MSTORE => {
-				InstructionCost::GasMem(default_gas, self.mem_needed_const(stack.peek(0), 32))
+				InstructionCost::GasMem(default_gas, try!(self.mem_needed_const(stack.peek(0), 32)))
 			},
 			instructions::MLOAD => {
-				InstructionCost::GasMem(default_gas, self.mem_needed_const(stack.peek(0), 32))
+				InstructionCost::GasMem(default_gas, try!(self.mem_needed_const(stack.peek(0), 32)))
 			},
 			instructions::MSTORE8 => {
-				InstructionCost::GasMem(default_gas, self.mem_needed_const(stack.peek(0), 1))
+				InstructionCost::GasMem(default_gas, try!(self.mem_needed_const(stack.peek(0), 1)))
 			},
 			instructions::RETURN => {
-				InstructionCost::GasMem(default_gas, self.mem_needed(stack.peek(0), stack.peek(1)))
+				InstructionCost::GasMem(default_gas, try!(self.mem_needed(stack.peek(0), stack.peek(1))))
 			},
 			instructions::SHA3 => {
-				match add_u256_usize(stack.peek(1), 31) {
+				let w = overflowing!(add_u256_usize(stack.peek(1), 31));
-					(_w, true) => InstructionCost::GasMem(U256::zero(), RequiredMem::OutOfMemory),
-					(w, false) => {
 				let words = w >> 5;
 				let gas = U256::from(schedule.sha3_gas) + (U256::from(schedule.sha3_word_gas) * words);
-						InstructionCost::GasMem(gas, self.mem_needed(stack.peek(0), stack.peek(1)))
+				InstructionCost::GasMem(gas, try!(self.mem_needed(stack.peek(0), stack.peek(1))))
-					}
-				}
 			},
 			instructions::CALLDATACOPY => {
-				InstructionCost::GasMemCopy(default_gas, self.mem_needed(stack.peek(0), stack.peek(2)), stack.peek(2).clone())
+				InstructionCost::GasMemCopy(default_gas, try!(self.mem_needed(stack.peek(0), stack.peek(2))), stack.peek(2).clone())
 			},
 			instructions::CODECOPY => {
-				InstructionCost::GasMemCopy(default_gas, self.mem_needed(stack.peek(0), stack.peek(2)), stack.peek(2).clone())
+				InstructionCost::GasMemCopy(default_gas, try!(self.mem_needed(stack.peek(0), stack.peek(2))), stack.peek(2).clone())
 			},
 			instructions::EXTCODECOPY => {
-				InstructionCost::GasMemCopy(default_gas, self.mem_needed(stack.peek(1), stack.peek(3)), stack.peek(3).clone())
+				InstructionCost::GasMemCopy(default_gas, try!(self.mem_needed(stack.peek(1), stack.peek(3))), stack.peek(3).clone())
 			},
 			instructions::JUMPDEST => {
 				InstructionCost::Gas(U256::one())
@@ -409,50 +408,41 @@ impl Interpreter {
 			instructions::LOG0...instructions::LOG4 => {
 				let no_of_topics = instructions::get_log_topics(instruction);
 				let log_gas = schedule.log_gas + schedule.log_topic_gas * no_of_topics;
-				// TODO [todr] potential overflow of datagass
+
-				let data_gas = stack.peek(1).clone() * U256::from(schedule.log_data_gas);
+				let data_gas = overflowing!(stack.peek(1).overflowing_mul(U256::from(schedule.log_data_gas)));
-				let gas = try!(self.gas_add(data_gas, U256::from(log_gas)));
+				let gas = overflowing!(data_gas.overflowing_add(U256::from(log_gas)));
-				InstructionCost::GasMem(gas, self.mem_needed(stack.peek(0), stack.peek(1)))
+				InstructionCost::GasMem(gas, try!(self.mem_needed(stack.peek(0), stack.peek(1))))
 			},
 			instructions::CALL | instructions::CALLCODE => {
-				match add_u256_usize(stack.peek(0), schedule.call_gas) {
+				let mut gas  = overflowing!(add_u256_usize(stack.peek(0), schedule.call_gas));
-					(_gas, true) => InstructionCost::GasMem(U256::zero(), RequiredMem::OutOfMemory),
+				let mem = cmp::max(
-					(mut gas, false) => {
+					try!(self.mem_needed(stack.peek(5), stack.peek(6))),
-						let mem = self.mem_max(
+					try!(self.mem_needed(stack.peek(3), stack.peek(4)))
-							self.mem_needed(stack.peek(5), stack.peek(6)),
-							self.mem_needed(stack.peek(3), stack.peek(4))
 				);
 				
 				let address = u256_to_address(stack.peek(1));
 
-						// TODO [todr] Potential overflows
 				if instruction == instructions::CALL && !ext.exists(&address) {
-							gas = gas + U256::from(schedule.call_new_account_gas);
+					gas = overflowing!(gas.overflowing_add(U256::from(schedule.call_new_account_gas)));
 				};
 
 				if stack.peek(2).clone() > U256::zero() {
-							gas = gas + U256::from(schedule.call_value_transfer_gas)
+					gas = overflowing!(gas.overflowing_add(U256::from(schedule.call_value_transfer_gas)));
 				};
 
 				InstructionCost::GasMem(gas,mem)
-					}
-				}
 			},
 			instructions::DELEGATECALL => {
-				match add_u256_usize(stack.peek(0), schedule.call_gas) {
+				let gas = overflowing!(add_u256_usize(stack.peek(0), schedule.call_gas));
-					(_gas, true) => InstructionCost::GasMem(U256::zero(), RequiredMem::OutOfMemory),
+				let mem = cmp::max(
-					(gas, false) => {
+					try!(self.mem_needed(stack.peek(4), stack.peek(5))),
-						let mem = self.mem_max(
+					try!(self.mem_needed(stack.peek(2), stack.peek(3)))
-							self.mem_needed(stack.peek(4), stack.peek(5)),
-							self.mem_needed(stack.peek(2), stack.peek(3))
 				);
 				InstructionCost::GasMem(gas, mem)
-					}
-				}
 			},
 			instructions::CREATE => {
 				let gas = U256::from(schedule.create_gas);
-				let mem = self.mem_needed(stack.peek(1), stack.peek(2));
+				let mem = try!(self.mem_needed(stack.peek(1), stack.peek(2)));
 				InstructionCost::GasMem(gas, mem)
 			},
 			instructions::EXP => {
@@ -468,84 +458,57 @@ impl Interpreter {
 			InstructionCost::Gas(gas) => {
 				Ok((gas, 0))
 			},
-			InstructionCost::GasMem(gas, mem_size) => match mem_size {
+			InstructionCost::GasMem(gas, mem_size) => {
-				RequiredMem::Mem(mem_size) => {
+				let (mem_gas, new_mem_size) = try!(self.mem_gas_cost(schedule, mem.size(), &mem_size));
-					let (mem_gas, new_mem_size) = self.mem_gas_cost(schedule, mem.size(), &mem_size);
+				let gas = overflowing!(gas.overflowing_add(mem_gas));
-					let gas = try!(self.gas_add(gas, mem_gas));
 				Ok((gas, new_mem_size))
 			},
-				RequiredMem::OutOfMemory => Err(evm::Error::OutOfGas)
+			InstructionCost::GasMemCopy(gas, mem_size, copy) => {
-			},
+				let (mem_gas, new_mem_size) = try!(self.mem_gas_cost(schedule, mem.size(), &mem_size));
-			InstructionCost::GasMemCopy(gas, mem_size, copy) => match mem_size {
+				let copy = overflowing!(add_u256_usize(&copy, 31));
-				RequiredMem::Mem(mem_size) => {
-					let (mem_gas, new_mem_size) = self.mem_gas_cost(schedule, mem.size(), &mem_size);
-					match add_u256_usize(&copy, 31) {
-						(_c, true) => Err(evm::Error::OutOfGas),
-						(copy, false) => {
 				let copy_gas = U256::from(schedule.copy_gas) * (copy / U256::from(32));
-							let gas = try!(self.gas_add(try!(self.gas_add(gas, copy_gas)), mem_gas));
+				let gas = overflowing!(gas.overflowing_add(copy_gas));
+				let gas = overflowing!(gas.overflowing_add(mem_gas));
 				Ok((gas, new_mem_size))
 			}
 		}
-				},
-				RequiredMem::OutOfMemory => Err(evm::Error::OutOfGas)
-			}
-		}
 	}
 
-	fn gas_add(&self, a: U256, b: U256) -> Result<U256, evm::Error> {
+	fn mem_gas_cost(&self, schedule: &evm::Schedule, current_mem_size: usize, mem_size: &U256) -> Result<(U256, usize), evm::Error> {
-		match a.overflowing_add(b) {
-			(_val, true) => Err(evm::Error::OutOfGas),
-			(val, false) => Ok(val)
-		}
-	}
-	
-	fn mem_gas_cost(&self, schedule: &evm::Schedule, current_mem_size: usize, mem_size: &U256) -> (U256, usize) {
 		let gas_for_mem = |mem_size: U256| {
 			let s = mem_size >> 5;
-			s * U256::from(schedule.memory_gas) + s * s / U256::from(schedule.quad_coeff_div)
+			// s * memory_gas + s * s / quad_coeff_div
+			let a = overflowing!(s.overflowing_mul(U256::from(schedule.memory_gas)));
+			// We need to go to U512 to calculate s*s/quad_coeff_div
+			let b = U512::from(s) * U512::from(s) / U512::from(schedule.quad_coeff_div);
+			if b > U512::from(!U256::zero()) {
+				Err(evm::Error::OutOfGas)
+			} else {
+				Ok(overflowing!(a.overflowing_add(U256::from(b))))
+			}
 		};
 		let current_mem_size = U256::from(current_mem_size);
-		let req_mem_size_rounded = ((mem_size.clone() + U256::from(31)) >> 5) << 5;
+		let req_mem_size_rounded = (overflowing!(mem_size.overflowing_add(U256::from(31))) >> 5) << 5;
-		let new_mem_gas = gas_for_mem(U256::from(req_mem_size_rounded));
+		let new_mem_gas = try!(gas_for_mem(U256::from(req_mem_size_rounded)));
-		let current_mem_gas = gas_for_mem(current_mem_size);
+		let current_mem_gas = try!(gas_for_mem(current_mem_size));
 
-		(if req_mem_size_rounded > current_mem_size {
+		Ok((if req_mem_size_rounded > current_mem_size {
 			new_mem_gas - current_mem_gas
 		} else {
 			U256::zero()
-		}, req_mem_size_rounded.low_u64() as usize)
+		}, req_mem_size_rounded.low_u64() as usize))
 	}
 
-	fn mem_max(&self, m_a: RequiredMem, m_b: RequiredMem) -> RequiredMem {
+	fn mem_needed_const(&self, mem: &U256, add: usize) -> Result<U256, evm::Error> {
-		match (m_a, m_b) {
+		Ok(overflowing!(mem.overflowing_add(U256::from(add))))
-			(RequiredMem::Mem(a), RequiredMem::Mem(b)) => {
-				RequiredMem::Mem(cmp::max(a, b))
-			},
-			(RequiredMem::OutOfMemory, _) | (_, RequiredMem::OutOfMemory) => {
-				RequiredMem::OutOfMemory
-			}
-		}
 	}
 
-	fn mem_needed_const(&self, mem: &U256, add: usize) -> RequiredMem {
+	fn mem_needed(&self, offset: &U256, size: &U256) -> Result<U256, ::evm::Error> {
-		match mem.overflowing_add(U256::from(add)) {
-			(_, true) => RequiredMem::OutOfMemory,
-			(mem, false) => RequiredMem::Mem(mem)
-		}
-	}
-
-	fn mem_needed(&self, offset: &U256, size: &U256) -> RequiredMem {
 		if self.is_zero(size) {
-			return RequiredMem::Mem(U256::zero());
+			return Ok(U256::zero());
 		}
 
-		match offset.clone().overflowing_add(size.clone()) {
+		Ok(overflowing!(offset.overflowing_add(size.clone())))
-			(_result, true) => RequiredMem::OutOfMemory,
-			(result, false) => {
-					RequiredMem::Mem(result)
-			}
-		}
 	}
 
 	fn exec_instruction(&self,
@@ -646,7 +609,6 @@ impl Interpreter {
 
 				return match call_result {
 					MessageCallResult::Success(gas_left) => {
-						println!("Unused: {}", gas_left);
 						stack.push(U256::one());
 						Ok(InstructionResult::UnusedGas(gas_left))
 					},
@@ -906,41 +868,34 @@ impl Interpreter {
 			instructions::ADD => {
 				let a = stack.pop_back();
 				let b = stack.pop_back();
-				let (c, _overflow) = a.overflowing_add(b);
+				stack.push(a.overflowing_add(b).0);
-				stack.push(c);
 			},
 			instructions::MUL => {
 				let a = stack.pop_back();
 				let b = stack.pop_back();
-				let (c, _overflow) = a.overflowing_mul(b);
+				stack.push(a.overflowing_mul(b).0);
-				stack.push(c);
 			},
 			instructions::SUB => {
 				let a = stack.pop_back();
 				let b = stack.pop_back();
-				let (c, _overflow) = a.overflowing_sub(b);
+				stack.push(a.overflowing_sub(b).0);
-				stack.push(c);
 			},
 			instructions::DIV => {
 				let a = stack.pop_back();
 				let b = stack.pop_back();
-				stack.push(match !self.is_zero(&b) {
+				stack.push(if !self.is_zero(&b) {
-					true => {
+					a.overflowing_div(b).0
-						let (c, _overflow) = a.overflowing_div(b);
+				} else {
-						c
+					U256::zero() 
-					},
-					false => U256::zero()
 				});
 			},
 			instructions::MOD => {
 				let a = stack.pop_back();
 				let b = stack.pop_back();
-				stack.push(match !self.is_zero(&b) {
+				stack.push(if !self.is_zero(&b) {
-					true => {
+					a.overflowing_rem(b).0
-						let (c, _overflow) = a.overflowing_rem(b);
+				} else {
-						c
+					U256::zero()
-					},
-					false => U256::zero()
 				});
 			},
 			instructions::SDIV => {
@@ -954,7 +909,7 @@ impl Interpreter {
 				} else if a == min && b == !U256::zero() {
 					min
 				} else {
-					let (c, _overflow) = a.overflowing_div(b);
+					let c = a.overflowing_div(b).0;
 					set_sign(c, sign_a ^ sign_b)
 				});
 			},
@@ -962,10 +917,10 @@ impl Interpreter {
 				let ua = stack.pop_back();
 				let ub = stack.pop_back();
 				let (a, sign_a) = get_and_reset_sign(ua);
-				let (b, _sign_b) = get_and_reset_sign(ub);
+				let b = get_and_reset_sign(ub).0;
 
 				stack.push(if !self.is_zero(&b) {
-					let (c, _overflow) = a.overflowing_rem(b);
+					let c = a.overflowing_rem(b).0;
 					set_sign(c, sign_a)
 				} else {
 					U256::zero()
@@ -974,7 +929,7 @@ impl Interpreter {
 			instructions::EXP => {
 				let base = stack.pop_back();
 				let expon = stack.pop_back();
-				let (res, _overflow) = base.overflowing_pow(expon);
+				let res = base.overflowing_pow(expon).0;
 				stack.push(res);
 			},
 			instructions::NOT => {
@@ -1052,8 +1007,8 @@ impl Interpreter {
 				stack.push(if !self.is_zero(&c) {
 					// upcast to 512
 					let a5 = U512::from(a);
-					let (res, _overflow) = a5.overflowing_add(U512::from(b));
+					let res = a5.overflowing_add(U512::from(b)).0;
-					let (x, _overflow) = res.overflowing_rem(U512::from(c));
+					let x = res.overflowing_rem(U512::from(c)).0;
 					U256::from(x)
 				} else {
 					U256::zero()
@@ -1066,8 +1021,8 @@ impl Interpreter {
 
 				stack.push(if !self.is_zero(&c) {
 					let a5 = U512::from(a);
-					let (res, _overflow) = a5.overflowing_mul(U512::from(b));
+					let res = a5.overflowing_mul(U512::from(b)).0;
-					let (x, _overflow) = res.overflowing_rem(U512::from(c));
+					let x = res.overflowing_rem(U512::from(c)).0;
 					U256::from(x)
 				} else {
 					U256::zero()
@@ -1123,8 +1078,7 @@ fn get_and_reset_sign(value: U256) -> (U256, bool) {
 
 fn set_sign(value: U256, sign: bool) -> U256 {
 	if sign {
-		let (val, _overflow) = (!U256::zero() ^ value).overflowing_add(U256::one());
+		(!U256::zero() ^ value).overflowing_add(U256::one()).0
-		val
 	} else {
 		value
 	}
@@ -1145,6 +1099,23 @@ fn address_to_u256(value: Address) -> U256 {
 	U256::from(H256::from(value).as_slice())
 }
 
+#[test]
+fn test_mem_gas_cost() {
+	// given
+	let interpreter = Interpreter;
+	let schedule = evm::Schedule::default();
+	let current_mem_size = 5;
+	let mem_size = !U256::zero();
+
+	// when
+	let result = interpreter.mem_gas_cost(&schedule, current_mem_size, &mem_size);
+
+	// then
+	if let Ok(_) = result {
+		assert!(false, "Should fail with OutOfGas");
+	}
+}
+
 #[cfg(test)]
 mod tests {
 	use common::*;
@@ -1173,7 +1144,7 @@ mod tests {
 		let mem_size = U256::from(5);
 	
 		// when
-		let (mem_cost, mem_size) = interpreter.mem_gas_cost(&schedule, current_mem_size, &mem_size);
+		let (mem_cost, mem_size) = interpreter.mem_gas_cost(&schedule, current_mem_size, &mem_size).unwrap();
 
 		// then
 		assert_eq!(mem_cost, U256::from(3));

src/executive.rs

@@ -171,7 +171,7 @@ impl<'a> Executive<'a> {
 
 		// at first, transfer value to destination
 		self.state.transfer_balance(&params.sender, &params.address, &params.value);
-		debug!("Executive::call(params={:?}) self.env_info={:?}", params, self.info);
+		trace!("Executive::call(params={:?}) self.env_info={:?}", params, self.info);
 
 		if self.engine.is_builtin(&params.code_address) {
 			// if destination is builtin, try to execute it

src/lib.rs

@@ -82,6 +82,7 @@ extern crate heapsize;
 extern crate crypto;
 extern crate time;
 extern crate env_logger;
+extern crate num_cpus;
 #[cfg(feature = "jit" )]
 extern crate evmjit;
 #[macro_use]

src/queue.rs

@@ -1,59 +1,245 @@
+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::*;
 
 /// A queue of blocks. Sits between network or other I/O and the BlockChain.
 /// Sorts them ready for blockchain insertion.
 pub struct BlockQueue {
 	engine: Arc<Box<Engine>>,
+	more_to_verify: Arc<Condvar>,
+	verification: Arc<Mutex<Verification>>,
+	verifiers: Vec<JoinHandle<()>>,
+	deleting: Arc<AtomicBool>,
+	ready_signal: Arc<QueueSignal>,
+	processing: HashSet<H256>
+}
+
+struct UnVerifiedBlock {
+	header: Header,
+	bytes: Bytes,
+}
+
+struct VerifyingBlock {
+	hash: H256,
+	block: Option<PreVerifiedBlock>,
+}
+
+struct QueueSignal {
+	signalled: AtomicBool,
 	message_channel: IoChannel<NetSyncMessage>,
+}
+
+impl QueueSignal {
+	fn set(&self) {
+		if self.signalled.compare_and_swap(false, true, AtomicOrdering::Relaxed) == false {
+			self.message_channel.send(UserMessage(SyncMessage::BlockVerified)).expect("Error sending BlockVerified message");
+		}
+	}
+	fn reset(&self) {
+		self.signalled.store(false, AtomicOrdering::Relaxed);
+	}
+}
+
+#[derive(Default)]
+struct Verification {
+	unverified: VecDeque<UnVerifiedBlock>,
+	verified: VecDeque<PreVerifiedBlock>,
+	verifying: VecDeque<VerifyingBlock>,
 	bad: HashSet<H256>,
 }
 
 impl BlockQueue {
 	/// Creates a new queue instance.
 	pub fn new(engine: Arc<Box<Engine>>, message_channel: IoChannel<NetSyncMessage>) -> BlockQueue {
+		let verification = Arc::new(Mutex::new(Verification::default()));
+		let more_to_verify = Arc::new(Condvar::new());
+		let ready_signal = Arc::new(QueueSignal { signalled: AtomicBool::new(false), message_channel: message_channel });
+		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 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)));
+		}
 		BlockQueue {
 			engine: engine,
-			message_channel: message_channel,
+			ready_signal: ready_signal.clone(),
-			bad: HashSet::new(),
+			more_to_verify: more_to_verify.clone(),
+			verification: verification.clone(),
+			verifiers: verifiers,
+			deleting: deleting.clone(),
+			processing: HashSet::new(),
+		}
+	}
+
+	fn verify(verification: Arc<Mutex<Verification>>, engine: Arc<Box<Engine>>, wait: Arc<Condvar>, ready: Arc<QueueSignal>, deleting: Arc<AtomicBool>) {
+		while !deleting.load(AtomicOrdering::Relaxed) {
+			{
+				let mut lock = verification.lock().unwrap();
+				while lock.unverified.is_empty() && !deleting.load(AtomicOrdering::Relaxed) {
+					lock = wait.wait(lock).unwrap();
+				}
+				
+				if deleting.load(AtomicOrdering::Relaxed) {
+					return;
+				}
+			}
+
+			let block = {
+				let mut v = verification.lock().unwrap();
+				if v.unverified.is_empty() {
+					continue;
+				}
+				let block = v.unverified.pop_front().unwrap();
+				v.verifying.push_back(VerifyingBlock{ hash: block.header.hash(), block: None });
+				block
+			};
+
+			let block_hash = block.header.hash();
+			match verify_block_unordered(block.header, block.bytes, engine.deref().deref()) {
+				Ok(verified) => {
+					let mut v = verification.lock().unwrap();
+					for e in &mut v.verifying {
+						if e.hash == block_hash {
+							e.block = Some(verified);
+							break;
+						}
+					}
+					if !v.verifying.is_empty() && v.verifying.front().unwrap().hash == block_hash {
+						// we're next!
+						let mut vref = v.deref_mut();
+						BlockQueue::drain_verifying(&mut vref.verifying, &mut vref.verified, &mut vref.bad);
+						ready.set();
+					}
+				},
+				Err(err) => {
+					let mut v = verification.lock().unwrap();
+					warn!(target: "client", "Stage 2 block verification failed for {}\nError: {:?}", block_hash, err);
+					v.bad.insert(block_hash.clone());
+					v.verifying.retain(|e| e.hash != block_hash);
+					let mut vref = v.deref_mut();
+					BlockQueue::drain_verifying(&mut vref.verifying, &mut vref.verified, &mut vref.bad);
+					ready.set();
+				}
+			}
+		}
+	}
+
+	fn drain_verifying(verifying: &mut VecDeque<VerifyingBlock>, verified: &mut VecDeque<PreVerifiedBlock>, bad: &mut HashSet<H256>) {
+		while !verifying.is_empty() && verifying.front().unwrap().block.is_some() {
+			let block = verifying.pop_front().unwrap().block.unwrap();
+			if bad.contains(&block.header.parent_hash) {
+				bad.insert(block.header.hash());
+			}
+			else {
+				verified.push_back(block);
+			}
 		}
 	}
 
 	/// Clear the queue and stop verification activity.
 	pub fn clear(&mut self) {
+		let mut verification = self.verification.lock().unwrap();
+		verification.unverified.clear();
+		verification.verifying.clear();
 	}
 
 	/// Add a block to the queue.
-	pub fn import_block(&mut self, bytes: &[u8]) -> ImportResult {
+	pub fn import_block(&mut self, bytes: Bytes) -> ImportResult {
-		let header = BlockView::new(bytes).header();
+		let header = BlockView::new(&bytes).header();
-		if self.bad.contains(&header.hash()) {
+		if self.processing.contains(&header.hash()) {
+			return Err(ImportError::AlreadyQueued);
+		}
+		{
+			let mut verification = self.verification.lock().unwrap();
+			if verification.bad.contains(&header.hash()) {
 				return Err(ImportError::Bad(None));
 			}
 
-		if self.bad.contains(&header.parent_hash) {
+			if verification.bad.contains(&header.parent_hash) {
-			self.bad.insert(header.hash());
+				verification.bad.insert(header.hash());
 				return Err(ImportError::Bad(None));
 			}
+		}
 
-		try!(verify_block_basic(&header, bytes, self.engine.deref().deref()).map_err(|e| {
+		match verify_block_basic(&header, &bytes, self.engine.deref().deref()) {
-			warn!(target: "client", "Stage 1 block verification failed for {}\nError: {:?}", BlockView::new(&bytes).header_view().sha3(), e);
+			Ok(()) => {
-			e
+				self.processing.insert(header.hash());
-		}));
+				self.verification.lock().unwrap().unverified.push_back(UnVerifiedBlock { header: header, bytes: bytes });
-		try!(verify_block_unordered(&header, bytes, self.engine.deref().deref()).map_err(|e| {
+				self.more_to_verify.notify_all();
-			warn!(target: "client", "Stage 2 block verification failed for {}\nError: {:?}", BlockView::new(&bytes).header_view().sha3(), e);
+			},
-			e
+			Err(err) => {
-		}));
+				warn!(target: "client", "Stage 1 block verification failed for {}\nError: {:?}", BlockView::new(&bytes).header_view().sha3(), err);
-		try!(self.message_channel.send(UserMessage(SyncMessage::BlockVerified(bytes.to_vec()))).map_err(|e| Error::from(e)));
+				self.verification.lock().unwrap().bad.insert(header.hash());
+			}
+		}
 		Ok(())
 	}
 
+	/// Mark given block and all its children as bad. Stops verification.
 	pub fn mark_as_bad(&mut self, hash: &H256) {
-		self.bad.insert(hash.clone());
+		let mut verification_lock = self.verification.lock().unwrap();
-		//TODO: walk the queue
+		let mut verification = verification_lock.deref_mut();
+		verification.bad.insert(hash.clone());
+		let mut new_verified = VecDeque::new();
+		for block in verification.verified.drain(..) {
+			if verification.bad.contains(&block.header.parent_hash) {
+				verification.bad.insert(block.header.hash());
+			}
+			else {
+				new_verified.push_back(block);
+			}
+		}
+		verification.verified = new_verified;
+	}
+
+	pub fn drain(&mut self, max: usize) -> Vec<PreVerifiedBlock> {
+		let mut verification = self.verification.lock().unwrap();
+		let count = min(max, verification.verified.len());
+		let mut result = Vec::with_capacity(count);
+		for _ in 0..count {
+			let block = verification.verified.pop_front().unwrap();
+			self.processing.remove(&block.header.hash());
+			result.push(block);
+		}
+		self.ready_signal.reset();
+		result
 	}
 }
 
+impl Drop for BlockQueue {
+	fn drop(&mut self) {
+		self.clear();
+		self.deleting.store(true, AtomicOrdering::Relaxed);
+		self.more_to_verify.notify_all();
+		for t in self.verifiers.drain(..) {
+			t.join().unwrap();
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use util::*;
+	use spec::*;
+	use queue::*;
+
+	#[test]
+	fn test_block_queue() {
+		// TODO better test
+		let spec = Spec::new_test();
+		let engine = spec.to_engine().unwrap();
+		let _ = BlockQueue::new(Arc::new(engine), IoChannel::disconnected());
+	}
+}

src/service.rs

@@ -54,8 +54,8 @@ impl IoHandler<NetSyncMessage> for ClientIoHandler {
 	#[allow(match_ref_pats)]
 	fn message<'s>(&'s mut self, _io: &mut IoContext<'s, NetSyncMessage>, net_message: &'s mut NetSyncMessage) {
 		if let &mut UserMessage(ref mut message) = net_message {
-			if let &mut SyncMessage::BlockVerified(ref mut bytes) = message {
+			if let &mut SyncMessage::BlockVerified= message {
-				self.client.write().unwrap().import_verified_block(mem::replace(bytes, Bytes::new()));
+				self.client.write().unwrap().import_verified_blocks();
 			}
 		}
 	}

src/state.rs

@@ -150,10 +150,10 @@ impl State {
 		let e = try!(Executive::new(self, env_info, engine).transact(t));
 		//println!("Executed: {:?}", e);
 
-		debug!("Applied transaction. Diff:\n{}\n", StateDiff::diff_pod(&old, &self.to_pod()));
+		trace!("Applied transaction. Diff:\n{}\n", StateDiff::diff_pod(&old, &self.to_pod()));
 		self.commit();
 		let receipt = Receipt::new(self.root().clone(), e.cumulative_gas_used, e.logs);
-		debug!("Transaction receipt: {:?}", receipt);
+		trace!("Transaction receipt: {:?}", receipt);
 		Ok(receipt)
 	}
 

src/sync/chain.rs

@@ -401,7 +401,7 @@ impl ChainSync {
 		let header_view = HeaderView::new(header_rlp.as_raw());
 		// TODO: Decompose block and add to self.headers and self.bodies instead
 		if header_view.number() == From::from(self.last_imported_block + 1) {
-			match io.chain().import_block(block_rlp.as_raw()) {
+			match io.chain().import_block(block_rlp.as_raw().to_vec()) {
 				Err(ImportError::AlreadyInChain) => {
 					trace!(target: "sync", "New block already in chain {:?}", h);
 				},
@@ -655,7 +655,7 @@ impl ChainSync {
 				block_rlp.append_raw(body.at(0).as_raw(), 1);
 				block_rlp.append_raw(body.at(1).as_raw(), 1);
 				let h = &headers.1[i].hash;
-				match io.chain().import_block(&block_rlp.out()) {
+				match io.chain().import_block(block_rlp.out()) {
 					Err(ImportError::AlreadyInChain) => {
 						trace!(target: "sync", "Block already in chain {:?}", h);
 						self.last_imported_block = headers.0 + i as BlockNumber;

src/sync/mod.rs

@@ -43,7 +43,7 @@ pub enum SyncMessage {
 	/// New block has been imported into the blockchain
 	NewChainBlock(Bytes),
 	/// A block is ready 
-	BlockVerified(Bytes),
+	BlockVerified,
 }
 
 pub type NetSyncMessage = NetworkIoMessage<SyncMessage>;

src/sync/tests.rs

@@ -43,7 +43,7 @@ impl TestBlockChainClient {
 			rlp.append(&header);
 			rlp.append_raw(&rlp::NULL_RLP, 1);
 			rlp.append_raw(uncles.as_raw(), 1);
-			self.import_block(rlp.as_raw()).unwrap();
+			self.import_block(rlp.as_raw().to_vec()).unwrap();
 		}
 	}
 }
@@ -110,7 +110,7 @@ impl BlockChainClient for TestBlockChainClient {
 		None
 	}
 
-	fn import_block(&mut self, b: &[u8]) -> ImportResult {
+	fn import_block(&mut 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() {
@@ -132,7 +132,7 @@ 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.to_vec());
+			self.blocks.insert(header.hash(), b);
 			self.numbers.insert(number, header.hash());
 			let mut parent_hash = header.parent_hash;
 			if number > 0 {

src/verification.rs

@@ -9,6 +9,16 @@ use common::*;
 use engine::Engine;
 use blockchain::*;
 
+/// Preprocessed block data gathered in `verify_block_unordered` call
+pub struct PreVerifiedBlock {
+	/// Populated block header
+	pub header: Header,
+	/// Populated block transactions
+	pub transactions: Vec<Transaction>,
+	/// Block bytes
+	pub bytes: Bytes,
+}
+
 /// Phase 1 quick block verification. Only does checks that are cheap. Operates on a single block
 pub fn verify_block_basic(header: &Header, bytes: &[u8], engine: &Engine) -> Result<(), Error> {
 	try!(verify_header(&header, engine));
@@ -29,19 +39,26 @@ pub fn verify_block_basic(header: &Header, bytes: &[u8], engine: &Engine) -> Res
 
 /// Phase 2 verification. Perform costly checks such as transaction signatures and block nonce for ethash.
 /// Still operates on a individual block
-/// TODO: return cached transactions, header hash.
+/// Returns a PreVerifiedBlock structure populated with transactions
-pub fn verify_block_unordered(header: &Header, bytes: &[u8], engine: &Engine) -> Result<(), Error> {
+pub fn verify_block_unordered(header: Header, bytes: Bytes, engine: &Engine) -> Result<PreVerifiedBlock, Error> {
-	try!(engine.verify_block_unordered(&header, Some(bytes)));
+	try!(engine.verify_block_unordered(&header, Some(&bytes)));
-	for u in Rlp::new(bytes).at(2).iter().map(|rlp| rlp.as_val::<Header>()) {
+	for u in Rlp::new(&bytes).at(2).iter().map(|rlp| rlp.as_val::<Header>()) {
 		try!(engine.verify_block_unordered(&u, None));
 	}
 	// Verify transactions. 
-	// TODO: pass in pre-recovered transactions - maybe verify_transaction wants to call `sender()`.
+	let mut transactions = Vec::new();
-	let v = BlockView::new(bytes);
+	{
+		let v = BlockView::new(&bytes);
 		for t in v.transactions() {
 			try!(engine.verify_transaction(&t, &header));
+			transactions.push(t);
 		}
-	Ok(())
+	}
+	Ok(PreVerifiedBlock {
+		header: header,
+		transactions: transactions,
+		bytes: bytes,
+	})
 }
 
 /// Phase 3 verification. Check block information against parent and uncles.

src/views.rs

@@ -61,6 +61,44 @@ impl<'a> Hashable for TransactionView<'a> {
 	}
 }
 
+/// View onto transaction rlp.
+pub struct AccountView<'a> {
+	rlp: Rlp<'a>
+}
+
+impl<'a> AccountView<'a> {
+	/// Creates new view onto block from raw bytes.
+	pub fn new(bytes: &'a [u8]) -> AccountView<'a> {
+		AccountView {
+			rlp: Rlp::new(bytes)
+		}
+	}
+
+	/// Creates new view onto block from rlp.
+	pub fn new_from_rlp(rlp: Rlp<'a>) -> AccountView<'a> {
+		AccountView {
+			rlp: rlp
+		}
+	}
+
+	/// Return reference to underlaying rlp.
+	pub fn rlp(&self) -> &Rlp<'a> {
+		&self.rlp
+	}
+
+	/// Get the nonce field of the transaction.
+	pub fn nonce(&self) -> U256 { self.rlp.val_at(0) }
+
+	/// Get the gas_price field of the transaction.
+	pub fn balance(&self) -> U256 { self.rlp.val_at(1) }
+
+	/// Get the gas field of the transaction.
+	pub fn storage_root(&self) -> H256 { self.rlp.val_at(2) }
+
+	/// Get the value field of the transaction.
+	pub fn code_hash(&self) -> H256 { self.rlp.val_at(3) }
+}
+
 /// View onto block rlp.
 pub struct BlockView<'a> {
 	rlp: Rlp<'a>
@@ -97,13 +135,13 @@ impl<'a> BlockView<'a> {
 	}
 
 	/// Return List of transactions in given block.
-	pub fn transaction_views(&self) -> Vec<TransactionView> {
+	pub fn transactions(&self) -> Vec<Transaction> {
-		self.rlp.at(1).iter().map(TransactionView::new_from_rlp).collect()
+		self.rlp.val_at(1)
 	}
 
 	/// Return List of transactions in given block.
-	pub fn transactions(&self) -> Vec<Transaction> {
+	pub fn transaction_views(&self) -> Vec<TransactionView> {
-		self.rlp.val_at(1)
+		self.rlp.at(1).iter().map(TransactionView::new_from_rlp).collect()
 	}
 
 	/// Return transaction hashes.
@@ -116,6 +154,11 @@ impl<'a> BlockView<'a> {
 		self.rlp.val_at(2)
 	}
 
+	/// 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()
+	}
+
 	/// Return list of uncle hashes of given block.
 	pub fn uncle_hashes(&self) -> Vec<H256> {
 		self.rlp.at(2).iter().map(|rlp| rlp.as_raw().sha3()).collect()

util/Cargo.toml

@@ -5,10 +5,6 @@ license = "GPL-3.0"
 name = "ethcore-util"
 version = "0.1.0"
 authors = ["Ethcore <admin@ethcore.io>"]
-build = "build.rs"
-
-[build-dependencies]
-gcc = "0.3"
 
 [dependencies]
 log = "0.3"
@@ -27,6 +23,7 @@ elastic-array = "0.4"
 heapsize = "0.2"
 itertools = "0.4"
 slab = { git = "https://github.com/arkpar/slab.git" }
+sha3 = { path = "sha3" }
 
 [dev-dependencies]
 json-tests = { path = "json-tests" }

util/sha3/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+description = "Rust bindings for tinykeccak C library"
+homepage = "http://ethcore.io"
+license = "GPL-3.0"
+name = "sha3"
+version = "0.1.0"
+authors = ["Ethcore <admin@ethcore.io>"]
+build = "build.rs"
+
+[build-dependencies]
+gcc = "0.3"

util/sha3/src/lib.rs

@@ -0,0 +1,4 @@
+extern {
+	pub fn sha3_256(out: *mut u8, outlen: usize, input: *const u8, inputlen: usize) -> i32;
+	pub fn sha3_512(out: *mut u8, outlen: usize, input: *const u8, inputlen: usize) -> i32;
+}

util/src/hash.rs

@@ -215,10 +215,14 @@ macro_rules! impl_hash {
 		}
 		impl fmt::Display for $from {
 			fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-				for i in self.0[0..3].iter() {
+				for i in self.0[0..2].iter() {
 					try!(write!(f, "{:02x}", i));
 				}
-				write!(f, "…{:02x}", self.0.last().unwrap())
+				try!(write!(f, "…"));
+				for i in self.0[$size - 4..$size].iter() {
+					try!(write!(f, "{:02x}", i));
+				}
+				Ok(())
 			}
 		}
 
@@ -544,7 +548,7 @@ mod tests {
 	fn hash() {
 		let h = H64([0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef]);
 		assert_eq!(H64::from_str("0123456789abcdef").unwrap(), h);
-		assert_eq!(format!("{}", h), "012345…ef");
+		assert_eq!(format!("{}", h), "0123…89abcdef");
 		assert_eq!(format!("{:?}", h), "0123456789abcdef");
 		assert_eq!(h.hex(), "0123456789abcdef");
 		assert!(h == h);

util/src/io/service.rs

@@ -151,14 +151,22 @@ impl<Message> Handler for IoManager<Message> where Message: Send + 'static {
 /// Allows sending messages into the event loop. All the IO handlers will get the message
 /// in the `message` callback.
 pub struct IoChannel<Message> where Message: Send {
-	channel: Sender<IoMessage<Message>> 
+	channel: Option<Sender<IoMessage<Message>>>
 }
 
 impl<Message> IoChannel<Message> where Message: Send {
-	pub fn send(&mut self, message: Message) -> Result<(), IoError> {
+	/// Send a msessage through the channel
-		try!(self.channel.send(IoMessage::UserMessage(message)));
+	pub fn send(&self, message: Message) -> Result<(), IoError> {
+		if let Some(ref channel) = self.channel {
+			try!(channel.send(IoMessage::UserMessage(message)));
+		}
 		Ok(())
 	}
+
+	/// Create a new channel to connected to event loop.
+	pub fn disconnected() -> IoChannel<Message> {
+		IoChannel { channel: None }
+	}
 }
 
 /// General IO Service. Starts an event loop and dispatches IO requests.
@@ -198,7 +206,7 @@ impl<Message> IoService<Message> where Message: Send + 'static {
 
 	/// Create a new message channel
 	pub fn channel(&mut self) -> IoChannel<Message> {
-		IoChannel { channel: self.host_channel.clone() }
+		IoChannel { channel: Some(self.host_channel.clone()) }
 	}
 }
 

util/src/network/host.rs

@@ -561,13 +561,13 @@ impl<Message> IoHandler<NetworkIoMessage<Message>> for Host<Message> where Messa
 		let port = self.info.config.listen_address.port();
 		self.info.listen_port = port;
 
-//		self.add_node("enode://a9a921de2ff09a9a4d38b623c67b2d6b477a8e654ae95d874750cbbcb31b33296496a7b4421934e2629269e180823e52c15c2b19fc59592ec51ffe4f2de76ed7@127.0.0.1:30303");
+		self.add_node("enode://a9a921de2ff09a9a4d38b623c67b2d6b477a8e654ae95d874750cbbcb31b33296496a7b4421934e2629269e180823e52c15c2b19fc59592ec51ffe4f2de76ed7@127.0.0.1:30303");
-		// GO bootnodes
+/*		// GO bootnodes
 		self.add_node("enode://a979fb575495b8d6db44f750317d0f4622bf4c2aa3365d6af7c284339968eef29b69ad0dce72a4d8db5ebb4968de0e3bec910127f134779fbcb0cb6d3331163c@52.16.188.185:30303"); // IE
 		self.add_node("enode://de471bccee3d042261d52e9bff31458daecc406142b401d4cd848f677479f73104b9fdeb090af9583d3391b7f10cb2ba9e26865dd5fca4fcdc0fb1e3b723c786@54.94.239.50:30303");  // BR
 		self.add_node("enode://1118980bf48b0a3640bdba04e0fe78b1add18e1cd99bf22d53daac1fd9972ad650df52176e7c7d89d1114cfef2bc23a2959aa54998a46afcf7d91809f0855082@52.74.57.123:30303");  // SG
 		// ETH/DEV cpp-ethereum (poc-9.ethdev.com)
-		self.add_node("enode://979b7fa28feeb35a4741660a16076f1943202cb72b6af70d327f053e248bab9ba81760f39d0701ef1d8f89cc1fbd2cacba0710a12cd5314d5e0c9021aa3637f9@5.1.83.226:30303");
+		self.add_node("enode://979b7fa28feeb35a4741660a16076f1943202cb72b6af70d327f053e248bab9ba81760f39d0701ef1d8f89cc1fbd2cacba0710a12cd5314d5e0c9021aa3637f9@5.1.83.226:30303");*/
 	}
 
 	fn stream_hup<'s>(&'s mut self, io: &mut IoContext<'s, NetworkIoMessage<Message>>, stream: StreamToken) {

util/src/nibbleslice.rs

@@ -34,6 +34,22 @@ pub struct NibbleSlice<'a> {
 	offset_encode_suffix: usize,
 }
 
+pub struct NibbleSliceIterator<'a> {
+	p: &'a NibbleSlice<'a>,
+	i: usize,
+}
+
+impl<'a> Iterator for NibbleSliceIterator<'a> {
+	type Item = u8;
+	fn next(&mut self) -> Option<u8> {
+		self.i += 1;
+		match self.i <= self.p.len() {
+			true => Some(self.p.at(self.i - 1)),
+			false => None,
+		}
+	}
+}
+
 impl<'a, 'view> NibbleSlice<'a> where 'a: 'view {
 	/// Create a new nibble slice with the given byte-slice.
 	pub fn new(data: &[u8]) -> NibbleSlice { NibbleSlice::new_offset(data, 0) }
@@ -41,7 +57,7 @@ impl<'a, 'view> NibbleSlice<'a> where 'a: 'view {
 	/// Create a new nibble slice with the given byte-slice with a nibble offset.
 	pub fn new_offset(data: &'a [u8], offset: usize) -> NibbleSlice { NibbleSlice{data: data, offset: offset, data_encode_suffix: &b""[..], offset_encode_suffix: 0} }
 
-	/// 
+	/// Create a composed nibble slice; one followed by the other.
 	pub fn new_composed(a: &'a NibbleSlice, b: &'a NibbleSlice) -> NibbleSlice<'a> { NibbleSlice{data: a.data, offset: a.offset, data_encode_suffix: b.data, offset_encode_suffix: b.offset} }
 
 	/*pub fn new_composed_bytes_offset(a: &NibbleSlice, b: &NibbleSlice) -> (Bytes, usize) {
@@ -60,6 +76,10 @@ impl<'a, 'view> NibbleSlice<'a> where 'a: 'view {
 		(r, a.len() + b.len())
 	}*/
 
+	pub fn iter(&'a self) -> NibbleSliceIterator<'a> {
+		NibbleSliceIterator { p: self, i: 0 }
+	}
+
 	/// Create a new nibble slice from the given HPE encoded data (e.g. output of `encoded()`).
 	pub fn from_encoded(data: &'a [u8]) -> (NibbleSlice, bool) {
 		(Self::new_offset(data, if data[0] & 16 == 16 {1} else {2}), data[0] & 32 == 32)
@@ -189,6 +209,14 @@ mod tests {
 		}
 	}
 
+	#[test]
+	fn iterator() {
+		let n = NibbleSlice::new(D);
+		let mut nibbles: Vec<u8> = vec![];
+		nibbles.extend(n.iter());
+		assert_eq!(nibbles, (0u8..6).collect::<Vec<_>>())
+	}
+
 	#[test]
 	fn mid() {
 		let n = NibbleSlice::new(D);

util/src/overlaydb.rs

@@ -70,7 +70,9 @@ impl OverlayDB {
 		let mut ret = 0u32;
 		for i in self.overlay.drain().into_iter() {
 			let (key, (value, rc)) = i;
-			if rc != 0 {
+			// until we figure out state trie pruning, only commit stuff when it has a strictly positive delkta of RCs - 
+			// this prevents RCs being reduced to 0 where the DB would pretent that the node had been removed.
+			if rc > 0 {
 				match self.payload(&key) {
 					Some(x) => {
 						let (back_value, back_rc) = x;

util/src/sha3.rs

@@ -1,14 +1,13 @@
 //! Wrapper around tiny-keccak crate.
+extern crate sha3 as sha3_ext;
 
 use std::mem::uninitialized;
 use bytes::{BytesConvertable, Populatable};
 use hash::{H256, FixedHash};
+use self::sha3_ext::*;
 
 pub const SHA3_EMPTY: H256 = H256( [0xc5, 0xd2, 0x46, 0x01, 0x86, 0xf7, 0x23, 0x3c, 0x92, 0x7e, 0x7d, 0xb2, 0xdc, 0xc7, 0x03, 0xc0, 0xe5, 0x00, 0xb6, 0x53, 0xca, 0x82, 0x27, 0x3b, 0x7b, 0xfa, 0xd8, 0x04, 0x5d, 0x85, 0xa4, 0x70] );
 
-extern {
-	fn sha3_256(out: *mut u8, outlen: usize, input: *const u8, inputlen: usize) -> i32;
-}
 
 /// Types implementing this trait are sha3able.
 ///

util/src/trie/node.rs

@@ -5,7 +5,7 @@ use rlp::*;
 use super::journal::*;
 
 /// Type of node in the trie and essential information thereof.
-#[derive(Eq, PartialEq, Debug)]
+#[derive(Clone, Eq, PartialEq, Debug)]
 pub enum Node<'a> {
 	Empty,
 	Leaf(NibbleSlice<'a>, &'a[u8]),

util/src/trie/triedb.rs

@@ -42,7 +42,7 @@ impl<'db> TrieDB<'db> {
 	/// Panics, if `root` does not exist
 	pub fn new(db: &'db HashDB, root: &'db H256) -> Self {
 		if !db.exists(root) {
-			flush(format!("Trie root not found {}", root));
+			flushln!("TrieDB::new({}): Trie root not found!", root);
 			panic!("Trie root not found!");
 		}
 		TrieDB { 
@@ -109,7 +109,12 @@ impl<'db> TrieDB<'db> {
 
 	/// Get the root node's RLP.
 	fn root_node(&self) -> Node {
-		Node::decoded(self.db.lookup(&self.root).expect("Trie root not found!"))
+		Node::decoded(self.root_data())
+	}
+
+	/// Get the data of the root node.
+	fn root_data(&self) -> &[u8] {
+		self.db.lookup(&self.root).expect("Trie root not found!")
 	}
 
 	/// Get the root node as a `Node`.
@@ -198,6 +203,122 @@ impl<'db> TrieDB<'db> {
 	}
 }
 
+#[derive(Clone, Eq, PartialEq)]
+enum Status {
+	Entering,
+	At,
+	AtChild(usize),
+	Exiting,
+}
+
+#[derive(Clone, Eq, PartialEq)]
+struct Crumb<'a> {
+	node: Node<'a>,
+//	key: &'a[u8],
+	status: Status,
+}
+
+impl<'a> Crumb<'a> {
+	/// Move on to next status in the node's sequence.
+	fn increment(&mut self) {
+		self.status = match (&self.status, &self.node) {
+			(_, &Node::Empty) => Status::Exiting,
+			(&Status::Entering, _) => Status::At,
+			(&Status::At, &Node::Branch(_, _)) => Status::AtChild(0),
+			(&Status::AtChild(x), &Node::Branch(_, _)) if x < 15 => Status::AtChild(x + 1),
+			_ => Status::Exiting,
+		}
+	}
+}
+
+/// Iterator for going through all values in the trie.
+#[derive(Clone)]
+pub struct TrieDBIterator<'a> {
+	db: &'a TrieDB<'a>,
+	trail: Vec<Crumb<'a>>,
+	key_nibbles: Bytes,
+}
+
+impl<'a> TrieDBIterator<'a> {
+	/// Create a new iterator.
+	fn new(db: &'a TrieDB) -> TrieDBIterator<'a> {
+		let mut r = TrieDBIterator {
+			db: db,
+			trail: vec![],
+			key_nibbles: Vec::new(),
+		};
+		r.descend(db.root_data());
+		r
+	}
+
+	/// Descend into a payload.
+	fn descend(&mut self, d: &'a [u8]) {
+		self.trail.push(Crumb {
+			status: Status::Entering,
+			node: self.db.get_node(d)
+		});
+		match self.trail.last().unwrap().node {
+			Node::Leaf(n, _) | Node::Extension(n, _) => { self.key_nibbles.extend(n.iter()); },
+			_ => {}
+		}
+	}
+
+	/// Descend into a payload and get the next item.
+	fn descend_next(&mut self, d: &'a [u8]) -> Option<(Bytes, &'a [u8])> { self.descend(d); self.next() }
+
+	/// The present key.
+	fn key(&self) -> Bytes {
+		// collapse the key_nibbles down to bytes.
+		self.key_nibbles.iter().step(2).zip(self.key_nibbles.iter().skip(1).step(2)).map(|(h, l)| h * 16 + l).collect()
+	}
+}
+
+impl<'a> Iterator for TrieDBIterator<'a> {
+	type Item = (Bytes, &'a [u8]);
+
+	fn next(&mut self) -> Option<Self::Item> {
+		let b = match self.trail.last_mut() {
+			Some(ref mut b) => { b.increment(); b.clone() },
+			None => return None
+		};
+		match (b.status, b.node) {
+			(Status::Exiting, n) => {
+				match n {
+					Node::Leaf(n, _) | Node::Extension(n, _) => {
+						let l = self.key_nibbles.len();
+						self.key_nibbles.truncate(l - n.len());
+					},
+					Node::Branch(_, _) => { self.key_nibbles.pop(); },
+					_ => {}
+				}
+				self.trail.pop();
+				self.next()
+			},
+			(Status::At, Node::Leaf(_, v)) => Some((self.key(), v)),
+			(Status::At, Node::Extension(_, d)) => self.descend_next(d),
+			(Status::At, Node::Branch(_, Some(v))) => Some((self.key(), v)),
+			(Status::At, Node::Branch(_, _)) => self.next(),
+			(Status::AtChild(i), Node::Branch(children, _)) if children[i].len() > 0 => {
+				match i {
+					0 => self.key_nibbles.push(0),
+					i => *self.key_nibbles.last_mut().unwrap() = i as u8,
+				}
+				self.descend_next(children[i])
+			},
+			(Status::AtChild(i), Node::Branch(_, _)) => {
+				if i == 0 { self.key_nibbles.push(0); }
+				self.next()
+			},
+			_ => panic!() // Should never see Entering or AtChild without a Branch here.
+		}
+	}
+}
+
+impl<'db> TrieDB<'db> {
+	/// Get all keys/values stored in the trie.
+	pub fn iter(&self) -> TrieDBIterator { TrieDBIterator::new(self) }
+}
+
 impl<'db> Trie for TrieDB<'db> {
 	fn root(&self) -> &H256 { &self.root }
 
@@ -218,3 +339,22 @@ impl<'db> fmt::Debug for TrieDB<'db> {
 		writeln!(f, "]")
 	}
 }
+
+#[test]
+fn iterator() {
+	use memorydb::*;
+	use super::triedbmut::*;
+	
+	let d = vec![ &b"A"[..], &b"AA"[..], &b"AB"[..], &b"B"[..] ];
+
+	let mut memdb = MemoryDB::new();
+	let mut root = H256::new();
+	{
+		let mut t = TrieDBMut::new(&mut memdb, &mut root);
+		for x in &d {
+			t.insert(&x, &x);
+		}
+	}
+	assert_eq!(d.iter().map(|i|i.to_vec()).collect::<Vec<_>>(), TrieDB::new(&memdb, &root).iter().map(|x|x.0).collect::<Vec<_>>());
+	assert_eq!(d, TrieDB::new(&memdb, &root).iter().map(|x|x.1).collect::<Vec<_>>());
+}

util/src/trie/triedbmut.rs

@@ -65,8 +65,9 @@ impl<'db> TrieDBMut<'db> {
 		r 
 	}
 
-	/// Create a new trie with the backing database `db` and `root`
+	/// Create a new trie with the backing database `db` and `root`.
-	/// Panics, if `root` does not exist
+	/// Panics, if `root` does not exist.
+	// TODO: return Result<Self, TrieError>
 	pub fn from_existing(db: &'db mut HashDB, root: &'db mut H256) -> Self {
 		if !db.exists(root) {
 			flush(format!("Trie root not found {}", root));