Merge branch 'master' into trie_recursion

2017-08-29 12:23:37 +02:00 · 2017-08-29 12:23:37 +02:00 · e390e6b0af
commit e390e6b0af
parent 9cb4c99e5b 96e9a73a1b
70 changed files with 1602 additions and 748 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@ -548,6 +548,7 @@ dependencies = [
 "bigint 4.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "heapsize 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "libc 0.2.21 (registry+https://github.com/rust-lang/crates.io-index)",
+ "plain_hasher 0.1.0",
 "rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
 "rustc-hex 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@ -935,6 +936,7 @@ dependencies = [
 "docopt 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "ethcore 1.8.0",
 "ethcore-util 1.8.0",
+ "ethjson 0.1.0",
 "evm 0.1.0",
 "panic_hook 0.1.0",
 "rustc-hex 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
@ -1613,6 +1615,21 @@ dependencies = [
 "ws2_32-sys 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

+[[package]]
+name = "node-health"
+version = "0.1.0"
+dependencies = [
+ "futures 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "futures-cpupool 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ntp 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-reactor 0.1.0",
+ "parking_lot 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "time 0.1.35 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "nodrop"
 version = "0.1.9"
@ -1821,6 +1838,7 @@ dependencies = [
 "isatty 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "jsonrpc-core 7.0.0 (git+https://github.com/paritytech/jsonrpc.git?branch=parity-1.7)",
 "log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "node-health 0.1.0",
 "num_cpus 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "number_prefix 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
 "panic_hook 0.1.0",
@ -1862,7 +1880,6 @@ dependencies = [
 "ethcore-util 1.8.0",
 "fetch 0.1.0",
 "futures 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "futures-cpupool 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 "itertools 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
 "jsonrpc-core 7.0.0 (git+https://github.com/paritytech/jsonrpc.git?branch=parity-1.7)",
 "jsonrpc-http-server 7.0.0 (git+https://github.com/paritytech/jsonrpc.git?branch=parity-1.7)",
@ -1870,7 +1887,7 @@ dependencies = [
 "log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 "mime 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "mime_guess 1.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "ntp 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "node-health 0.1.0",
 "parity-dapps-glue 1.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-hash-fetch 1.8.0",
 "parity-reactor 0.1.0",
@ -1985,6 +2002,7 @@ dependencies = [
 "jsonrpc-ws-server 7.0.0 (git+https://github.com/paritytech/jsonrpc.git?branch=parity-1.7)",
 "log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 "multihash 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "node-health 0.1.0",
 "order-stat 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-reactor 0.1.0",
 "parity-updater 1.8.0",
@ -2197,6 +2215,13 @@ name = "pkg-config"
 version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"

+[[package]]
+name = "plain_hasher"
+version = "0.1.0"
+dependencies = [
+ "crunchy 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "podio"
 version = "0.1.5"
--- a/Cargo.toml
+++ b/Cargo.toml
@ -43,6 +43,7 @@ ethcore-logger = { path = "logger" }
 ethcore-stratum = { path = "stratum" }
 ethcore-network = { path = "util/network" }
 ethkey = { path = "ethkey" }
+node-health = { path = "dapps/node-health" }
 rlp = { path = "util/rlp" }
 rpc-cli = { path = "rpc_cli" }
 parity-hash-fetch = { path = "hash-fetch" }
@ -110,4 +111,4 @@ lto = false
 panic = "abort"

 [workspace]
-members = ["ethstore/cli", "ethkey/cli", "evmbin", "whisper", "chainspec"]
+members = ["ethstore/cli", "ethkey/cli", "evmbin", "whisper", "chainspec", "dapps/node-health"]
--- a/dapps/Cargo.toml
+++ b/dapps/Cargo.toml
@ -9,15 +9,12 @@ authors = ["Parity Technologies <admin@parity.io>"]

 [dependencies]
 base32 = "0.3"
-env_logger = "0.4"
 futures = "0.1"
-futures-cpupool = "0.1"
 linked-hash-map = "0.3"
 log = "0.3"
 parity-dapps-glue = "1.7"
 mime = "0.2"
 mime_guess = "1.6.1"
-ntp = "0.2.0"
 rand = "0.3"
 rustc-hex = "1.0"
 serde = "1.0"
@ -32,15 +29,19 @@ itertools = "0.5"
 jsonrpc-core = { git = "https://github.com/paritytech/jsonrpc.git", branch = "parity-1.7" }
 jsonrpc-http-server = { git = "https://github.com/paritytech/jsonrpc.git", branch = "parity-1.7" }

-ethcore-devtools = { path = "../devtools" }
 ethcore-util = { path = "../util" }
 fetch = { path = "../util/fetch" }
+node-health = { path = "./node-health" }
 parity-hash-fetch = { path = "../hash-fetch" }
 parity-reactor = { path = "../util/reactor" }
 parity-ui = { path = "./ui" }

 clippy = { version = "0.0.103", optional = true}

+[dev-dependencies]
+env_logger = "0.4"
+ethcore-devtools = { path = "../devtools" }
+
 [features]
 dev = ["clippy", "ethcore-util/dev"]

--- a/dapps/node-health/Cargo.toml
+++ b/dapps/node-health/Cargo.toml
@ -0,0 +1,18 @@
+[package]
+name = "node-health"
+description = "Node's health status"
+version = "0.1.0"
+license = "GPL-3.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+
+[dependencies]
+futures = "0.1"
+futures-cpupool = "0.1"
+log = "0.3"
+ntp = "0.2.0"
+parking_lot = "0.4"
+serde = "1.0"
+serde_derive = "1.0"
+time = "0.1.35"
+
+parity-reactor = { path = "../../util/reactor" }
--- a/dapps/node-health/src/health.rs
+++ b/dapps/node-health/src/health.rs
@ -0,0 +1,122 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Reporting node's health.
+
+use std::sync::Arc;
+use std::time;
+use futures::{Future, BoxFuture};
+use futures::sync::oneshot;
+use types::{HealthInfo, HealthStatus, Health};
+use time::{TimeChecker, MAX_DRIFT};
+use parity_reactor::Remote;
+use parking_lot::Mutex;
+use {SyncStatus};
+
+const TIMEOUT_SECS: u64 = 5;
+const PROOF: &str = "Only one closure is invoked.";
+
+/// A struct enabling you to query for node's health.
+#[derive(Debug, Clone)]
+pub struct NodeHealth {
+	sync_status: Arc<SyncStatus>,
+	time: TimeChecker,
+	remote: Remote,
+}
+
+impl NodeHealth {
+	/// Creates new `NodeHealth`.
+	pub fn new(sync_status: Arc<SyncStatus>, time: TimeChecker, remote: Remote) -> Self {
+		NodeHealth { sync_status, time, remote, }
+	}
+
+	/// Query latest health report.
+	pub fn health(&self) -> BoxFuture<Health, ()> {
+		trace!(target: "dapps", "Checking node health.");
+		// Check timediff
+		let sync_status = self.sync_status.clone();
+		let time = self.time.time_drift();
+		let (tx, rx) = oneshot::channel();
+		let tx = Arc::new(Mutex::new(Some(tx)));
+		let tx2 = tx.clone();
+		self.remote.spawn_with_timeout(
+			move || time.then(move |result| {
+				let _ = tx.lock().take().expect(PROOF).send(Ok(result));
+				Ok(())
+			}),
+			time::Duration::from_secs(TIMEOUT_SECS),
+			move || {
+				let _ = tx2.lock().take().expect(PROOF).send(Err(()));
+			},
+		);
+
+		rx.map_err(|err| {
+			warn!(target: "dapps", "Health request cancelled: {:?}", err);
+		}).and_then(move |time| {
+			// Check peers
+			let peers = {
+				let (connected, max) = sync_status.peers();
+				let (status, message) = match connected {
+					0 => {
+						(HealthStatus::Bad, "You are not connected to any peers. There is most likely some network issue. Fix connectivity.".into())
+					},
+					1 => (HealthStatus::NeedsAttention, "You are connected to only one peer. Your node might not be reliable. Check your network connection.".into()),
+					_ => (HealthStatus::Ok, "".into()),
+				};
+				HealthInfo { status, message, details: (connected, max) }
+			};
+
+			// Check sync
+			let sync = {
+				let is_syncing = sync_status.is_major_importing();
+				let (status, message) = if is_syncing {
+					(HealthStatus::NeedsAttention, "Your node is still syncing, the values you see might be outdated. Wait until it's fully synced.".into())
+				} else {
+					(HealthStatus::Ok, "".into())
+				};
+				HealthInfo { status, message, details: is_syncing }
+			};
+
+			// Check time
+			let time = {
+				let (status, message, details) = match time {
+					Ok(Ok(diff)) if diff < MAX_DRIFT && diff > -MAX_DRIFT => {
+						(HealthStatus::Ok, "".into(), diff)
+					},
+					Ok(Ok(diff)) => {
+						(HealthStatus::Bad, format!(
+							"Your clock is not in sync. Detected difference is too big for the protocol to work: {}ms. Synchronize your clock.",
+							diff,
+						), diff)
+					},
+					Ok(Err(err)) => {
+						(HealthStatus::NeedsAttention, format!(
+							"Unable to reach time API: {}. Make sure that your clock is synchronized.",
+							err,
+						), 0)
+					},
+					Err(_) => {
+						(HealthStatus::NeedsAttention, "Time API request timed out. Make sure that the clock is synchronized.".into(), 0)
+					},
+				};
+
+				HealthInfo { status, message, details, }
+			};
+
+			Ok(Health { peers, sync, time})
+		}).boxed()
+	}
+}
--- a/dapps/node-health/src/lib.rs
+++ b/dapps/node-health/src/lib.rs
@ -0,0 +1,49 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Node Health status reporting.
+
+#![warn(missing_docs)]
+
+extern crate futures;
+extern crate futures_cpupool;
+extern crate ntp;
+extern crate time as time_crate;
+extern crate parity_reactor;
+extern crate parking_lot;
+
+#[macro_use]
+extern crate log;
+#[macro_use]
+extern crate serde_derive;
+
+mod health;
+mod time;
+mod types;
+
+pub use futures_cpupool::CpuPool;
+pub use health::NodeHealth;
+pub use types::{Health, HealthInfo, HealthStatus};
+pub use time::{TimeChecker, Error};
+
+/// Indicates sync status
+pub trait SyncStatus: ::std::fmt::Debug + Send + Sync {
+	/// Returns true if there is a major sync happening.
+	fn is_major_importing(&self) -> bool;
+
+	/// Returns number of connected and ideal peers.
+	fn peers(&self) -> (usize, usize);
+}
--- a/dapps/node-health/src/time.rs
+++ b/dapps/node-health/src/time.rs
@ -41,8 +41,8 @@ use futures::{self, Future, BoxFuture};
 use futures::future::{self, IntoFuture};
 use futures_cpupool::{CpuPool, CpuFuture};
 use ntp;
-use time::{Duration, Timespec};
-use util::RwLock;
+use parking_lot::RwLock;
+use time_crate::{Duration, Timespec};

 /// Time checker error.
 #[derive(Debug, Clone, PartialEq)]
@ -164,7 +164,7 @@ impl Ntp for SimpleNtp {

 				match ntp::request(&server.address) {
 					Ok(packet) => {
-						let dest_time = ::time::now_utc().to_timespec();
+						let dest_time = ::time_crate::now_utc().to_timespec();
 						let orig_time = Timespec::from(packet.orig_time);
 						let recv_time = Timespec::from(packet.recv_time);
 						let transmit_time = Timespec::from(packet.transmit_time);
@ -293,7 +293,7 @@ mod tests {
 	use time::Duration;
 	use futures::{future, Future};
 	use super::{Ntp, TimeChecker, Error};
-	use util::RwLock;
+	use parking_lot::RwLock;

 	#[derive(Clone)]
 	struct FakeNtp(RefCell<Vec<Duration>>, Cell<u64>);
--- a/dapps/node-health/src/types.rs
+++ b/dapps/node-health/src/types.rs
@ -0,0 +1,57 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Base health types.
+
+/// Health API endpoint status.
+#[derive(Debug, PartialEq, Serialize)]
+pub enum HealthStatus {
+	/// Everything's OK.
+	#[serde(rename = "ok")]
+	Ok,
+	/// Node health need attention
+	/// (the issue is not critical, but may need investigation)
+	#[serde(rename = "needsAttention")]
+	NeedsAttention,
+	/// There is something bad detected with the node.
+	#[serde(rename = "bad")]
+	Bad,
+}
+
+/// Represents a single check in node health.
+/// Cointains the status of that check and apropriate message and details.
+#[derive(Debug, PartialEq, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct HealthInfo<T> {
+	/// Check status.
+	pub status: HealthStatus,
+	/// Human-readable message.
+	pub message: String,
+	/// Technical details of the check.
+	pub details: T,
+}
+
+/// Node Health status.
+#[derive(Debug, PartialEq, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct Health {
+	/// Status of peers.
+	pub peers: HealthInfo<(usize, usize)>,
+	/// Sync status.
+	pub sync: HealthInfo<bool>,
+	/// Time diff info.
+	pub time: HealthInfo<i64>,
+}
--- a/dapps/src/api/api.rs
+++ b/dapps/src/api/api.rs
@ -21,32 +21,28 @@ use hyper::method::Method;
 use hyper::status::StatusCode;

 use api::{response, types};
-use api::time::{TimeChecker, MAX_DRIFT};
 use apps::fetcher::Fetcher;
 use handlers::{self, extract_url};
 use endpoint::{Endpoint, Handler, EndpointPath};
+use node_health::{NodeHealth, HealthStatus, Health};
 use parity_reactor::Remote;
-use {SyncStatus};

 #[derive(Clone)]
 pub struct RestApi {
 	fetcher: Arc<Fetcher>,
-	sync_status: Arc<SyncStatus>,
-	time: TimeChecker,
+	health: NodeHealth,
 	remote: Remote,
 }

 impl RestApi {
 	pub fn new(
 		fetcher: Arc<Fetcher>,
-		sync_status: Arc<SyncStatus>,
-		time: TimeChecker,
+		health: NodeHealth,
 		remote: Remote,
 	) -> Box<Endpoint> {
 		Box::new(RestApi {
 			fetcher,
-			sync_status,
-			time,
+			health,
 			remote,
 		})
 	}
@ -90,68 +86,23 @@ impl RestApiRouter {
 	}

 	fn health(&self, control: Control) -> Box<Handler> {
-		use self::types::{HealthInfo, HealthStatus, Health};
-
-		trace!(target: "dapps", "Checking node health.");
-		// Check timediff
-		let sync_status = self.api.sync_status.clone();
-		let map = move |time| {
-			// Check peers
-			let peers = {
-				let (connected, max) = sync_status.peers();
-				let (status, message) = match connected {
-					0 => {
-						(HealthStatus::Bad, "You are not connected to any peers. There is most likely some network issue. Fix connectivity.".into())
-					},
-					1 => (HealthStatus::NeedsAttention, "You are connected to only one peer. Your node might not be reliable. Check your network connection.".into()),
-					_ => (HealthStatus::Ok, "".into()),
-				};
-				HealthInfo { status, message, details: (connected, max) }
-			};
-
-			// Check sync
-			let sync = {
-				let is_syncing = sync_status.is_major_importing();
-				let (status, message) = if is_syncing {
-					(HealthStatus::NeedsAttention, "Your node is still syncing, the values you see might be outdated. Wait until it's fully synced.".into())
+		let map = move |health: Result<Result<Health, ()>, ()>| {
+			let status = match health {
+				Ok(Ok(ref health)) => {
+					if [&health.peers.status, &health.sync.status].iter().any(|x| *x != &HealthStatus::Ok) {
+						StatusCode::PreconditionFailed // HTTP 412
 					} else {
-					(HealthStatus::Ok, "".into())
-				};
-				HealthInfo { status, message, details: is_syncing }
+						StatusCode::Ok // HTTP 200
+					}
+				},
+				_ => StatusCode::ServiceUnavailable, // HTTP 503
 			};

-			// Check time
-			let time = {
-				let (status, message, details) = match time {
-					Ok(Ok(diff)) if diff < MAX_DRIFT && diff > -MAX_DRIFT => {
-						(HealthStatus::Ok, "".into(), diff)
-					},
-					Ok(Ok(diff)) => {
-						(HealthStatus::Bad, format!(
-							"Your clock is not in sync. Detected difference is too big for the protocol to work: {}ms. Synchronize your clock.",
-							diff,
-						), diff)
-					},
-					Ok(Err(err)) => {
-						(HealthStatus::NeedsAttention, format!(
-							"Unable to reach time API: {}. Make sure that your clock is synchronized.",
-							err,
-						), 0)
-					},
-					Err(_) => {
-						(HealthStatus::NeedsAttention, "Time API request timed out. Make sure that the clock is synchronized.".into(), 0)
-					},
+			response::as_json(status, &health)
 		};
-
-				HealthInfo { status, message, details, }
-			};
-
-			response::as_json(StatusCode::Ok, &Health { peers, sync, time })
-		};
-
-		let time = self.api.time.time_drift();
+		let health = self.api.health.health();
 		let remote = self.api.remote.clone();
-		Box::new(handlers::AsyncHandler::new(time, map, remote, control))
+		Box::new(handlers::AsyncHandler::new(health, map, remote, control))
 	}
 }

--- a/dapps/src/api/mod.rs
+++ b/dapps/src/api/mod.rs
@ -18,8 +18,6 @@

 mod api;
 mod response;
-mod time;
 mod types;

 pub use self::api::RestApi;
-pub use self::time::TimeChecker;
--- a/dapps/src/api/types.rs
+++ b/dapps/src/api/types.rs
@ -25,43 +25,3 @@ pub struct ApiError {
 	/// More technical error details.
 	pub detail: String,
 }
-
-/// Health API endpoint status.
-#[derive(Debug, PartialEq, Serialize)]
-pub enum HealthStatus {
-	/// Everything's OK.
-	#[serde(rename = "ok")]
-	Ok,
-	/// Node health need attention
-	/// (the issue is not critical, but may need investigation)
-	#[serde(rename = "needsAttention")]
-	NeedsAttention,
-	/// There is something bad detected with the node.
-	#[serde(rename = "bad")]
-	Bad
-}
-
-/// Represents a single check in node health.
-/// Cointains the status of that check and apropriate message and details.
-#[derive(Debug, PartialEq, Serialize)]
-#[serde(deny_unknown_fields)]
-pub struct HealthInfo<T> {
-	/// Check status.
-	pub status: HealthStatus,
-	/// Human-readable message.
-	pub message: String,
-	/// Technical details of the check.
-	pub details: T,
-}
-
-/// Node Health status.
-#[derive(Debug, PartialEq, Serialize)]
-#[serde(deny_unknown_fields)]
-pub struct Health {
-	/// Status of peers.
-	pub peers: HealthInfo<(usize, usize)>,
-	/// Sync status.
-	pub sync: HealthInfo<bool>,
-	/// Time diff info.
-	pub time: HealthInfo<i64>,
-}
--- a/dapps/src/apps/fetcher/mod.rs
+++ b/dapps/src/apps/fetcher/mod.rs
@ -281,6 +281,7 @@ mod tests {
 		}
 	}

+	#[derive(Debug)]
 	struct FakeSync(bool);
 	impl SyncStatus for FakeSync {
 		fn is_major_importing(&self) -> bool { self.0 }
--- a/dapps/src/lib.rs
+++ b/dapps/src/lib.rs
@ -21,11 +21,9 @@

 extern crate base32;
 extern crate futures;
-extern crate futures_cpupool;
 extern crate itertools;
 extern crate linked_hash_map;
 extern crate mime_guess;
-extern crate ntp;
 extern crate rand;
 extern crate rustc_hex;
 extern crate serde;
@ -40,6 +38,7 @@ extern crate jsonrpc_http_server;

 extern crate ethcore_util as util;
 extern crate fetch;
+extern crate node_health;
 extern crate parity_dapps_glue as parity_dapps;
 extern crate parity_hash_fetch as hash_fetch;
 extern crate parity_reactor;
@ -57,7 +56,6 @@ extern crate ethcore_devtools as devtools;
 #[cfg(test)]
 extern crate env_logger;

-
 mod endpoint;
 mod apps;
 mod page;
@ -79,19 +77,12 @@ use util::RwLock;
 use jsonrpc_http_server::{self as http, hyper, Origin};

 use fetch::Fetch;
-use futures_cpupool::CpuPool;
+use node_health::NodeHealth;
 use parity_reactor::Remote;

 pub use hash_fetch::urlhint::ContractClient;
+pub use node_health::SyncStatus;

-/// Indicates sync status
-pub trait SyncStatus: Send + Sync {
-	/// Returns true if there is a major sync happening.
-	fn is_major_importing(&self) -> bool;
-
-	/// Returns number of connected and ideal peers.
-	fn peers(&self) -> (usize, usize);
-}

 /// Validates Web Proxy tokens
 pub trait WebProxyTokens: Send + Sync {
@ -156,8 +147,7 @@ impl Middleware {

 	/// Creates new middleware for UI server.
 	pub fn ui<F: Fetch>(
-		ntp_servers: &[String],
-		pool: CpuPool,
+		health: NodeHealth,
 		remote: Remote,
 		dapps_domain: &str,
 		registrar: Arc<ContractClient>,
@ -172,11 +162,9 @@ impl Middleware {
 		).embeddable_on(None).allow_dapps(false));
 		let special = {
 			let mut special = special_endpoints(
-				ntp_servers,
-				pool,
+				health,
 				content_fetcher.clone(),
 				remote.clone(),
-				sync_status.clone(),
 			);
 			special.insert(router::SpecialEndpoint::Home, Some(apps::ui()));
 			special
@ -197,8 +185,7 @@ impl Middleware {

 	/// Creates new Dapps server middleware.
 	pub fn dapps<F: Fetch>(
-		ntp_servers: &[String],
-		pool: CpuPool,
+		health: NodeHealth,
 		remote: Remote,
 		ui_address: Option<(String, u16)>,
 		extra_embed_on: Vec<(String, u16)>,
@ -236,11 +223,9 @@ impl Middleware {

 		let special = {
 			let mut special = special_endpoints(
-				ntp_servers,
-				pool,
+				health,
 				content_fetcher.clone(),
 				remote.clone(),
-				sync_status,
 			);
 			special.insert(
 				router::SpecialEndpoint::Home,
@ -270,20 +255,17 @@ impl http::RequestMiddleware for Middleware {
 	}
 }

-fn special_endpoints<T: AsRef<str>>(
-	ntp_servers: &[T],
-	pool: CpuPool,
+fn special_endpoints(
+	health: NodeHealth,
 	content_fetcher: Arc<apps::fetcher::Fetcher>,
 	remote: Remote,
-	sync_status: Arc<SyncStatus>,
 ) -> HashMap<router::SpecialEndpoint, Option<Box<endpoint::Endpoint>>> {
 	let mut special = HashMap::new();
 	special.insert(router::SpecialEndpoint::Rpc, None);
 	special.insert(router::SpecialEndpoint::Utils, Some(apps::utils()));
 	special.insert(router::SpecialEndpoint::Api, Some(api::RestApi::new(
 		content_fetcher,
-		sync_status,
-		api::TimeChecker::new(ntp_servers, pool),
+		health,
 		remote,
 	)));
 	special
--- a/dapps/src/tests/helpers/mod.rs
+++ b/dapps/src/tests/helpers/mod.rs
@ -26,7 +26,7 @@ use jsonrpc_http_server::{self as http, Host, DomainsValidation};
 use devtools::http_client;
 use hash_fetch::urlhint::ContractClient;
 use fetch::{Fetch, Client as FetchClient};
-use futures_cpupool::CpuPool;
+use node_health::{NodeHealth, TimeChecker, CpuPool};
 use parity_reactor::Remote;

 use {Middleware, SyncStatus, WebProxyTokens};
@ -39,6 +39,7 @@ use self::fetch::FakeFetch;

 const SIGNER_PORT: u16 = 18180;

+#[derive(Debug)]
 struct FakeSync(bool);
 impl SyncStatus for FakeSync {
 	fn is_major_importing(&self) -> bool { self.0 }
@ -254,9 +255,13 @@ impl Server {
 		remote: Remote,
 		fetch: F,
 	) -> Result<Server, http::Error> {
+		let health = NodeHealth::new(
+			sync_status.clone(),
+			TimeChecker::new::<String>(&[], CpuPool::new(1)),
+			remote.clone(),
+		);
 		let middleware = Middleware::dapps(
-			&["0.pool.ntp.org:123".into(), "1.pool.ntp.org:123".into()],
-			CpuPool::new(4),
+			health,
 			remote,
 			signer_address,
 			vec![],
--- a/ethcore/evm/src/interpreter/memory.rs
+++ b/ethcore/evm/src/interpreter/memory.rs
@ -44,7 +44,7 @@ pub trait Memory {
 }

 /// Checks whether offset and size is valid memory range
-fn is_valid_range(off: usize, size: usize)  -> bool {
+pub fn is_valid_range(off: usize, size: usize)  -> bool {
 	// When size is zero we haven't actually expanded the memory
 	let overflow = off.overflowing_add(size).1;
 	size > 0 && !overflow
--- a/ethcore/evm/src/interpreter/mod.rs
+++ b/ethcore/evm/src/interpreter/mod.rs
@ -168,7 +168,12 @@ impl<Cost: CostType> vm::Vm for Interpreter<Cost> {
 			}

 			if do_trace {
-				ext.trace_executed(gasometer.current_gas.as_u256(), stack.peek_top(info.ret), mem_written.map(|(o, s)| (o, &(self.mem[o..(o + s)]))), store_written);
+				ext.trace_executed(
+					gasometer.current_gas.as_u256(),
+					stack.peek_top(info.ret),
+					mem_written.map(|(o, s)| (o, &(self.mem[o..o+s]))),
+					store_written,
+				);
 			}

 			// Advance
@ -252,14 +257,20 @@ impl<Cost: CostType> Interpreter<Cost> {
 		instruction: Instruction,
 		stack: &Stack<U256>
 	) -> Option<(usize, usize)> {
-		match instruction {
-			instructions::MSTORE | instructions::MLOAD => Some((stack.peek(0).low_u64() as usize, 32)),
-			instructions::MSTORE8 => Some((stack.peek(0).low_u64() as usize, 1)),
-			instructions::CALLDATACOPY | instructions::CODECOPY | instructions::RETURNDATACOPY => Some((stack.peek(0).low_u64() as usize, stack.peek(2).low_u64() as usize)),
-			instructions::EXTCODECOPY => Some((stack.peek(1).low_u64() as usize, stack.peek(3).low_u64() as usize)),
-			instructions::CALL | instructions::CALLCODE => Some((stack.peek(5).low_u64() as usize, stack.peek(6).low_u64() as usize)),
-			instructions::DELEGATECALL => Some((stack.peek(4).low_u64() as usize, stack.peek(5).low_u64() as usize)),
+		let read = |pos| stack.peek(pos).low_u64() as usize;
+		let written = match instruction {
+			instructions::MSTORE | instructions::MLOAD => Some((read(0), 32)),
+			instructions::MSTORE8 => Some((read(0), 1)),
+			instructions::CALLDATACOPY | instructions::CODECOPY | instructions::RETURNDATACOPY => Some((read(0), read(2))),
+			instructions::EXTCODECOPY => Some((read(1), read(3))),
+			instructions::CALL | instructions::CALLCODE => Some((read(5), read(6))),
+			instructions::DELEGATECALL | instructions::STATICCALL => Some((read(4), read(5))),
 			_ => None,
+		};
+
+		match written {
+			Some((offset, size)) if !memory::is_valid_range(offset, size) => None,
+			written => written,
 		}
 	}

@ -862,3 +873,36 @@ fn address_to_u256(value: Address) -> U256 {
 	U256::from(&*H256::from(value))
 }

+
+#[cfg(test)]
+mod tests {
+	use std::sync::Arc;
+	use rustc_hex::FromHex;
+	use vmtype::VMType;
+	use factory::Factory;
+	use vm::{self, ActionParams, ActionValue};
+	use vm::tests::{FakeExt, test_finalize};
+
+	#[test]
+	fn should_not_fail_on_tracing_mem() {
+		let code = "7feeffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff006000527faaffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffaa6020526000620f120660406000601773945304eb96065b2a98b57a48a06ae28d285a71b56101f4f1600055".from_hex().unwrap();
+
+		let mut params = ActionParams::default();
+		params.address = 5.into();
+		params.gas = 300_000.into();
+		params.gas_price = 1.into();
+		params.value = ActionValue::Transfer(100_000.into());
+		params.code = Some(Arc::new(code));
+		let mut ext = FakeExt::new();
+		ext.balances.insert(5.into(), 1_000_000_000.into());
+		ext.tracing = true;
+
+		let gas_left = {
+			let mut vm = Factory::new(VMType::Interpreter, 1).create(params.gas);
+			test_finalize(vm.exec(params, &mut ext)).unwrap()
+		};
+
+		assert_eq!(ext.calls.len(), 1);
+		assert_eq!(gas_left, 248_212.into());
+	}
+}
--- a/ethcore/res/wasm-tests
+++ b/ethcore/res/wasm-tests
@ -1 +1 @@
-Subproject commit 85e76c5ea2a54c6c54e35014643b5080a50460c5
+Subproject commit 519b0b967cffd7d1236ef21698b1e6e415a048e9
--- a/ethcore/src/client/client.rs
+++ b/ethcore/src/client/client.rs
@ -748,7 +748,7 @@ impl Client {
 								self.factories.clone(),
 							).expect("state known to be available for just-imported block; qed");

-							let options = TransactOptions { tracing: false, vm_tracing: false, check_nonce: false };
+							let options = TransactOptions::with_no_tracing().dont_check_nonce();
 							let res = Executive::new(&mut state, &env_info, &*self.engine)
 								.transact(&transaction, options);

@ -1113,19 +1113,40 @@ impl Client {
 		}.fake_sign(from)
 	}

-	fn do_call(&self, env_info: &EnvInfo, state: &mut State<StateDB>, t: &SignedTransaction, analytics: CallAnalytics) -> Result<Executed, CallError> {
-		let original_state = if analytics.state_diffing { Some(state.clone()) } else { None };
+	fn do_virtual_call(&self, env_info: &EnvInfo, state: &mut State<StateDB>, t: &SignedTransaction, analytics: CallAnalytics) -> Result<Executed, CallError> {
+		fn call<E, V, T>(
+			state: &mut State<StateDB>,
+			env_info: &EnvInfo,
+			engine: &E,
+			state_diff: bool,
+			transaction: &SignedTransaction,
+			options: TransactOptions<T, V>,
+		) -> Result<Executed, CallError> where
+			E: Engine + ?Sized,
+			T: trace::Tracer,
+			V: trace::VMTracer,
+		{
+			let options = options.dont_check_nonce();
+			let original_state = if state_diff { Some(state.clone()) } else { None };

-		let options = TransactOptions { tracing: analytics.transaction_tracing, vm_tracing: analytics.vm_tracing, check_nonce: false };
-		let mut ret = Executive::new(state, env_info, &*self.engine).transact_virtual(t, options)?;
+			let mut ret = Executive::new(state, env_info, engine).transact_virtual(transaction, options)?;

-		// TODO gav move this into Executive.
 			if let Some(original) = original_state {
 				ret.state_diff = Some(state.diff_from(original).map_err(ExecutionError::from)?);
 			}
-
 			Ok(ret)
 		}
+
+		let state_diff = analytics.state_diffing;
+		let engine = &*self.engine;
+
+		match (analytics.transaction_tracing, analytics.vm_tracing) {
+			(true, true) => call(state, env_info, engine, state_diff, t, TransactOptions::with_tracing_and_vm_tracing()),
+			(true, false) => call(state, env_info, engine, state_diff, t, TransactOptions::with_tracing()),
+			(false, true) => call(state, env_info, engine, state_diff, t, TransactOptions::with_vm_tracing()),
+			(false, false) => call(state, env_info, engine, state_diff, t, TransactOptions::with_no_tracing()),
+		}
+	}
 }

 impl snapshot::DatabaseRestore for Client {
@ -1157,7 +1178,7 @@ impl BlockChainClient for Client {
 		// that's just a copy of the state.
 		let mut state = self.state_at(block).ok_or(CallError::StatePruned)?;

-		self.do_call(&env_info, &mut state, transaction, analytics)
+		self.do_virtual_call(&env_info, &mut state, transaction, analytics)
 	}

 	fn call_many(&self, transactions: &[(SignedTransaction, CallAnalytics)], block: BlockId) -> Result<Vec<Executed>, CallError> {
@ -1169,7 +1190,7 @@ impl BlockChainClient for Client {
 		let mut results = Vec::with_capacity(transactions.len());

 		for &(ref t, analytics) in transactions {
-			let ret = self.do_call(&env_info, &mut state, t, analytics)?;
+			let ret = self.do_virtual_call(&env_info, &mut state, t, analytics)?;
 			env_info.gas_used = ret.cumulative_gas_used;
 			results.push(ret);
 		}
@ -1189,7 +1210,7 @@ impl BlockChainClient for Client {
 		// that's just a copy of the state.
 		let original_state = self.state_at(block).ok_or(CallError::StatePruned)?;
 		let sender = t.sender();
-		let options = TransactOptions { tracing: true, vm_tracing: false, check_nonce: false };
+		let options = || TransactOptions::with_tracing();

 		let cond = |gas| {
 			let mut tx = t.as_unsigned().clone();
@ -1198,7 +1219,7 @@ impl BlockChainClient for Client {

 			let mut state = original_state.clone();
 			Ok(Executive::new(&mut state, &env_info, &*self.engine)
-				.transact_virtual(&tx, options.clone())
+				.transact_virtual(&tx, options())
 				.map(|r| r.exception.is_none())
 				.unwrap_or(false))
 		};
@ -1254,22 +1275,17 @@ impl BlockChainClient for Client {
 			return Err(CallError::TransactionNotFound);
 		}

-		let options = TransactOptions { tracing: analytics.transaction_tracing, vm_tracing: analytics.vm_tracing, check_nonce: false };
 		const PROOF: &'static str = "Transactions fetched from blockchain; blockchain transactions are valid; qed";
 		let rest = txs.split_off(address.index);
 		for t in txs {
 			let t = SignedTransaction::new(t).expect(PROOF);
-			let x = Executive::new(&mut state, &env_info, &*self.engine).transact(&t, Default::default())?;
+			let x = Executive::new(&mut state, &env_info, &*self.engine).transact(&t, TransactOptions::with_no_tracing())?;
 			env_info.gas_used = env_info.gas_used + x.gas_used;
 		}
 		let first = rest.into_iter().next().expect("We split off < `address.index`; Length is checked earlier; qed");
 		let t = SignedTransaction::new(first).expect(PROOF);
-		let original_state = if analytics.state_diffing { Some(state.clone()) } else { None };
-		let mut ret = Executive::new(&mut state, &env_info, &*self.engine).transact(&t, options)?;
-		if let Some(original) = original_state {
-			ret.state_diff = Some(state.diff_from(original).map_err(ExecutionError::from)?)
-		}
-		Ok(ret)
+
+		self.do_virtual_call(&env_info, &mut state, &t, analytics)
 	}

 	fn mode(&self) -> IpcMode {
@ -1951,7 +1967,7 @@ impl ProvingBlockChainClient for Client {
 		let backend = state::backend::Proving::new(jdb.as_hashdb_mut());

 		let mut state = state.replace_backend(backend);
-		let options = TransactOptions { tracing: false, vm_tracing: false, check_nonce: false };
+		let options = TransactOptions::with_no_tracing().dont_check_nonce();
 		let res = Executive::new(&mut state, &env_info, &*self.engine).transact(&transaction, options);

 		match res {
--- a/ethcore/src/client/evm_test_client.rs
+++ b/ethcore/src/client/evm_test_client.rs
@ -18,9 +18,9 @@

 use std::fmt;
 use std::sync::Arc;
-use util::{self, U256, journaldb, trie};
+use util::{self, U256, H256, journaldb, trie};
 use util::kvdb::{self, KeyValueDB};
-use {state, state_db, client, executive, trace, db, spec};
+use {state, state_db, client, executive, trace, transaction, db, spec, pod_state};
 use factory::Factories;
 use evm::{self, VMType};
 use vm::{self, ActionParams};
@ -33,9 +33,17 @@ pub enum EvmTestError {
 	/// EVM error.
 	Evm(vm::Error),
 	/// Initialization error.
-	Initialization(::error::Error),
+	ClientError(::error::Error),
 	/// Low-level database error.
 	Database(String),
+	/// Post-condition failure,
+	PostCondition(String),
+}
+
+impl<E: Into<::error::Error>> From<E> for EvmTestError {
+	fn from(err: E) -> Self {
+		EvmTestError::ClientError(err.into())
+	}
 }

 impl fmt::Display for EvmTestError {
@ -45,52 +53,114 @@ impl fmt::Display for EvmTestError {
 		match *self {
 			Trie(ref err) => write!(fmt, "Trie: {}", err),
 			Evm(ref err) => write!(fmt, "EVM: {}", err),
-			Initialization(ref err) => write!(fmt, "Initialization: {}", err),
+			ClientError(ref err) => write!(fmt, "{}", err),
 			Database(ref err) => write!(fmt, "DB: {}", err),
+			PostCondition(ref err) => write!(fmt, "{}", err),
 		}
 	}
 }

+use ethereum;
+use ethjson::state::test::ForkSpec;
+
+lazy_static! {
+	pub static ref FRONTIER: spec::Spec = ethereum::new_frontier_test();
+	pub static ref HOMESTEAD: spec::Spec = ethereum::new_homestead_test();
+	pub static ref EIP150: spec::Spec = ethereum::new_eip150_test();
+	pub static ref EIP161: spec::Spec = ethereum::new_eip161_test();
+	pub static ref _METROPOLIS: spec::Spec = ethereum::new_metropolis_test();
+}
+
 /// Simplified, single-block EVM test client.
-pub struct EvmTestClient {
-	state_db: state_db::StateDB,
-	factories: Factories,
-	spec: spec::Spec,
+pub struct EvmTestClient<'a> {
+	state: state::State<state_db::StateDB>,
+	spec: &'a spec::Spec,
 }

-impl EvmTestClient {
-	/// Creates new EVM test client with in-memory DB initialized with genesis of given Spec.
-	pub fn new(spec: spec::Spec) -> Result<Self, EvmTestError> {
-		let factories = Factories {
-			vm: evm::Factory::new(VMType::Interpreter, 5 * 1024),
-			trie: trie::TrieFactory::new(trie::TrieSpec::Secure),
-			accountdb: Default::default(),
-		};
-		let db = Arc::new(kvdb::in_memory(db::NUM_COLUMNS.expect("We use column-based DB; qed")));
-		let journal_db = journaldb::new(db.clone(), journaldb::Algorithm::EarlyMerge, db::COL_STATE);
-		let mut state_db = state_db::StateDB::new(journal_db, 5 * 1024 * 1024);
-		state_db = spec.ensure_db_good(state_db, &factories).map_err(EvmTestError::Initialization)?;
-		// Write DB
-		{
-			let mut batch = kvdb::DBTransaction::new();
-			state_db.journal_under(&mut batch, 0, &spec.genesis_header().hash()).map_err(|e| EvmTestError::Initialization(e.into()))?;
-			db.write(batch).map_err(EvmTestError::Database)?;
+impl<'a> EvmTestClient<'a> {
+	/// Converts a json spec definition into spec.
+	pub fn spec_from_json(spec: &ForkSpec) -> Option<&'static spec::Spec> {
+		match *spec {
+			ForkSpec::Frontier => Some(&*FRONTIER),
+			ForkSpec::Homestead => Some(&*HOMESTEAD),
+			ForkSpec::EIP150 => Some(&*EIP150),
+			ForkSpec::EIP158 => Some(&*EIP161),
+			ForkSpec::Metropolis | ForkSpec::Byzantium | ForkSpec::Constantinople => None,
 		}
+	}
+
+	/// Creates new EVM test client with in-memory DB initialized with genesis of given Spec.
+	pub fn new(spec: &'a spec::Spec) -> Result<Self, EvmTestError> {
+		let factories = Self::factories();
+		let state =	Self::state_from_spec(spec, &factories)?;

 		Ok(EvmTestClient {
-			state_db,
-			factories,
+			state,
 			spec,
 		})
 	}

-	/// Call given contract.
+	/// Creates new EVM test client with in-memory DB initialized with given PodState.
+	pub fn from_pod_state(spec: &'a spec::Spec, pod_state: pod_state::PodState) -> Result<Self, EvmTestError> {
+		let factories = Self::factories();
+		let state =	Self::state_from_pod(spec, &factories, pod_state)?;
+
+		Ok(EvmTestClient {
+			state,
+			spec,
+		})
+	}
+
+	fn factories() -> Factories {
+		Factories {
+			vm: evm::Factory::new(VMType::Interpreter, 5 * 1024),
+			trie: trie::TrieFactory::new(trie::TrieSpec::Secure),
+			accountdb: Default::default(),
+		}
+	}
+
+	fn state_from_spec(spec: &'a spec::Spec, factories: &Factories) -> Result<state::State<state_db::StateDB>, EvmTestError> {
+		let db = Arc::new(kvdb::in_memory(db::NUM_COLUMNS.expect("We use column-based DB; qed")));
+		let journal_db = journaldb::new(db.clone(), journaldb::Algorithm::EarlyMerge, db::COL_STATE);
+		let mut state_db = state_db::StateDB::new(journal_db, 5 * 1024 * 1024);
+		state_db = spec.ensure_db_good(state_db, factories)?;
+
+		let genesis = spec.genesis_header();
+		// Write DB
+		{
+			let mut batch = kvdb::DBTransaction::new();
+			state_db.journal_under(&mut batch, 0, &genesis.hash())?;
+			db.write(batch).map_err(EvmTestError::Database)?;
+		}
+
+		state::State::from_existing(
+			state_db,
+			*genesis.state_root(),
+			spec.engine.account_start_nonce(0),
+			factories.clone()
+		).map_err(EvmTestError::Trie)
+	}
+
+	fn state_from_pod(spec: &'a spec::Spec, factories: &Factories, pod_state: pod_state::PodState) -> Result<state::State<state_db::StateDB>, EvmTestError> {
+		let db = Arc::new(kvdb::in_memory(db::NUM_COLUMNS.expect("We use column-based DB; qed")));
+		let journal_db = journaldb::new(db.clone(), journaldb::Algorithm::EarlyMerge, db::COL_STATE);
+		let state_db = state_db::StateDB::new(journal_db, 5 * 1024 * 1024);
+		let mut state = state::State::new(
+			state_db,
+			spec.engine.account_start_nonce(0),
+			factories.clone(),
+		);
+		state.populate_from(pod_state);
+		state.commit()?;
+		Ok(state)
+	}
+
+	/// Execute the VM given ActionParams and tracer.
+	/// Returns amount of gas left and the output.
 	pub fn call<T: trace::VMTracer>(&mut self, params: ActionParams, vm_tracer: &mut T)
 		-> Result<(U256, Vec<u8>), EvmTestError>
 	{
 		let genesis = self.spec.genesis_header();
-		let mut state = state::State::from_existing(self.state_db.boxed_clone(), *genesis.state_root(), self.spec.engine.account_start_nonce(0), self.factories.clone())
-			.map_err(EvmTestError::Trie)?;
 		let info = client::EnvInfo {
 			number: genesis.number(),
 			author: *genesis.author(),
@ -103,7 +173,7 @@ impl EvmTestClient {
 		let mut substate = state::Substate::new();
 		let mut tracer = trace::NoopTracer;
 		let mut output = vec![];
-		let mut executive = executive::Executive::new(&mut state, &info, &*self.spec.engine);
+		let mut executive = executive::Executive::new(&mut self.state, &info, &*self.spec.engine);
 		let (gas_left, _) = executive.call(
 			params,
 			&mut substate,
@ -114,4 +184,59 @@ impl EvmTestClient {

 		Ok((gas_left, output))
 	}
+
+	/// Executes a SignedTransaction within context of the provided state and `EnvInfo`.
+	/// Returns the state root, gas left and the output.
+	pub fn transact<T: trace::VMTracer>(
+		&mut self,
+		env_info: &client::EnvInfo,
+		transaction: transaction::SignedTransaction,
+		vm_tracer: T,
+	) -> TransactResult {
+		let initial_gas = transaction.gas;
+		// Verify transaction
+		let is_ok = transaction.verify_basic(true, None, env_info.number >= self.spec.engine.params().eip86_transition);
+		if let Err(error) = is_ok {
+			return TransactResult::Err {
+				state_root: *self.state.root(),
+				error,
+			};
+		}
+
+		// Apply transaction
+		let tracer = trace::NoopTracer;
+		let result = self.state.apply_with_tracing(&env_info, &*self.spec.engine, &transaction, tracer, vm_tracer);
+
+		match result {
+			Ok(result) => TransactResult::Ok {
+				state_root: *self.state.root(),
+				gas_left: initial_gas - result.receipt.gas_used,
+				output: result.output
+			},
+			Err(error) => TransactResult::Err {
+				state_root: *self.state.root(),
+				error,
+			},
+		}
+	}
+}
+
+/// A result of applying transaction to the state.
+pub enum TransactResult {
+	/// Successful execution
+	Ok {
+		/// State root
+		state_root: H256,
+		/// Amount of gas left
+		gas_left: U256,
+		/// Output
+		output: Vec<u8>,
+	},
+	/// Transaction failed to run
+	Err {
+		/// State root
+		state_root: H256,
+		/// Execution error
+		error: ::error::Error,
+	},
 }
--- a/ethcore/src/client/mod.rs
+++ b/ethcore/src/client/mod.rs
@ -27,7 +27,7 @@ mod client;
 pub use self::client::*;
 pub use self::config::{Mode, ClientConfig, DatabaseCompactionProfile, BlockChainConfig, VMType};
 pub use self::error::Error;
-pub use self::evm_test_client::{EvmTestClient, EvmTestError};
+pub use self::evm_test_client::{EvmTestClient, EvmTestError, TransactResult};
 pub use self::test_client::{TestBlockChainClient, EachBlockWith};
 pub use self::chain_notify::ChainNotify;
 pub use self::traits::{BlockChainClient, MiningBlockChainClient, EngineClient};
--- a/ethcore/src/executive.rs
+++ b/ethcore/src/executive.rs
@ -26,7 +26,7 @@ use evm::{CallType, Factory, Finalize, FinalizationResult};
 use vm::{self, Ext, CreateContractAddress, ReturnData, CleanDustMode, ActionParams, ActionValue};
 use wasm;
 use externalities::*;
-use trace::{FlatTrace, Tracer, NoopTracer, ExecutiveTracer, VMTrace, VMTracer, ExecutiveVMTracer, NoopVMTracer};
+use trace::{self, FlatTrace, VMTrace, Tracer, VMTracer};
 use transaction::{Action, SignedTransaction};
 use crossbeam;
 pub use executed::{Executed, ExecutionResult};
@ -66,16 +66,77 @@ pub fn contract_address(address_scheme: CreateContractAddress, sender: &Address,
 }

 /// Transaction execution options.
-#[derive(Default, Copy, Clone, PartialEq)]
-pub struct TransactOptions {
+#[derive(Copy, Clone, PartialEq)]
+pub struct TransactOptions<T, V> {
 	/// Enable call tracing.
-	pub tracing: bool,
+	pub tracer: T,
 	/// Enable VM tracing.
-	pub vm_tracing: bool,
+	pub vm_tracer: V,
 	/// Check transaction nonce before execution.
 	pub check_nonce: bool,
 }

+impl<T, V> TransactOptions<T, V> {
+	/// Create new `TransactOptions` with given tracer and VM tracer.
+	pub fn new(tracer: T, vm_tracer: V) -> Self {
+		TransactOptions {
+			tracer,
+			vm_tracer,
+			check_nonce: true,
+		}
+	}
+
+	/// Disables the nonce check
+	pub fn dont_check_nonce(mut self) -> Self {
+		self.check_nonce = false;
+		self
+	}
+}
+
+impl TransactOptions<trace::ExecutiveTracer, trace::ExecutiveVMTracer> {
+	/// Creates new `TransactOptions` with default tracing and VM tracing.
+	pub fn with_tracing_and_vm_tracing() -> Self {
+		TransactOptions {
+			tracer: trace::ExecutiveTracer::default(),
+			vm_tracer: trace::ExecutiveVMTracer::toplevel(),
+			check_nonce: true,
+		}
+	}
+}
+
+impl TransactOptions<trace::ExecutiveTracer, trace::NoopVMTracer> {
+	/// Creates new `TransactOptions` with default tracing and no VM tracing.
+	pub fn with_tracing() -> Self {
+		TransactOptions {
+			tracer: trace::ExecutiveTracer::default(),
+			vm_tracer: trace::NoopVMTracer,
+			check_nonce: true,
+		}
+	}
+}
+
+impl TransactOptions<trace::NoopTracer, trace::ExecutiveVMTracer> {
+	/// Creates new `TransactOptions` with no tracing and default VM tracing.
+	pub fn with_vm_tracing() -> Self {
+		TransactOptions {
+			tracer: trace::NoopTracer,
+			vm_tracer: trace::ExecutiveVMTracer::toplevel(),
+			check_nonce: true,
+		}
+	}
+}
+
+impl TransactOptions<trace::NoopTracer, trace::NoopVMTracer> {
+	/// Creates new `TransactOptions` without any tracing.
+	pub fn with_no_tracing() -> Self {
+		TransactOptions {
+			tracer: trace::NoopTracer,
+			vm_tracer: trace::NoopVMTracer,
+			check_nonce: true,
+		}
+	}
+}
+
 pub fn executor<E>(engine: &E, vm_factory: &Factory, params: &ActionParams)
 	-> Box<vm::Vm> where E: Engine + ?Sized
 {
@ -137,24 +198,18 @@ impl<'a, B: 'a + StateBackend, E: Engine + ?Sized> Executive<'a, B, E> {
 	}

 	/// This function should be used to execute transaction.
-	pub fn transact(&'a mut self, t: &SignedTransaction, options: TransactOptions) -> Result<Executed, ExecutionError> {
-		let check = options.check_nonce;
-		match options.tracing {
-			true => match options.vm_tracing {
-				true => self.transact_with_tracer(t, check, ExecutiveTracer::default(), ExecutiveVMTracer::toplevel()),
-				false => self.transact_with_tracer(t, check, ExecutiveTracer::default(), NoopVMTracer),
-			},
-			false => match options.vm_tracing {
-				true => self.transact_with_tracer(t, check, NoopTracer, ExecutiveVMTracer::toplevel()),
-				false => self.transact_with_tracer(t, check, NoopTracer, NoopVMTracer),
-			},
-		}
+	pub fn transact<T, V>(&'a mut self, t: &SignedTransaction, options: TransactOptions<T, V>)
+		-> Result<Executed, ExecutionError> where T: Tracer, V: VMTracer,
+	{
+		self.transact_with_tracer(t, options.check_nonce, options.tracer, options.vm_tracer)
 	}

 	/// Execute a transaction in a "virtual" context.
 	/// This will ensure the caller has enough balance to execute the desired transaction.
 	/// Used for extra-block executions for things like consensus contracts and RPCs
-	pub fn transact_virtual(&'a mut self, t: &SignedTransaction, options: TransactOptions) -> Result<Executed, ExecutionError> {
+	pub fn transact_virtual<T, V>(&'a mut self, t: &SignedTransaction, options: TransactOptions<T, V>)
+		-> Result<Executed, ExecutionError> where T: Tracer, V: VMTracer,
+	{
 		let sender = t.sender();
 		let balance = self.state.balance(&sender)?;
 		let needed_balance = t.value.saturating_add(t.gas.saturating_mul(t.gas_price));
@ -167,7 +222,7 @@ impl<'a, B: 'a + StateBackend, E: Engine + ?Sized> Executive<'a, B, E> {
 	}

 	/// Execute transaction/call with tracing enabled
-	pub fn transact_with_tracer<T, V>(
+	fn transact_with_tracer<T, V>(
 		&'a mut self,
 		t: &SignedTransaction,
 		check_nonce: bool,
@ -261,7 +316,7 @@ impl<'a, B: 'a + StateBackend, E: Engine + ?Sized> Executive<'a, B, E> {
 		};

 		// finalize here!
-		Ok(self.finalize(t, substate, result, output, tracer.traces(), vm_tracer.drain())?)
+		Ok(self.finalize(t, substate, result, output, tracer.drain(), vm_tracer.drain())?)
 	}

 	fn exec_vm<T, V>(
@ -399,7 +454,7 @@ impl<'a, B: 'a + StateBackend, E: Engine + ?Sized> Executive<'a, B, E> {

 				trace!(target: "executive", "res={:?}", res);

-				let traces = subtracer.traces();
+				let traces = subtracer.drain();
 				match res {
 					Ok(ref res) => tracer.trace_call(
 						trace_info,
@ -484,9 +539,9 @@ impl<'a, B: 'a + StateBackend, E: Engine + ?Sized> Executive<'a, B, E> {
 				gas - res.gas_left,
 				trace_output,
 				created,
-				subtracer.traces()
+				subtracer.drain()
 			),
-			Err(ref e) => tracer.trace_failed_create(trace_info, subtracer.traces(), e.into())
+			Err(ref e) => tracer.trace_failed_create(trace_info, subtracer.drain(), e.into())
 		};

 		self.enact_result(&res, substate, unconfirmed_substate);
@ -794,7 +849,7 @@ mod tests {
 			}),
 		}];

-		assert_eq!(tracer.traces(), expected_trace);
+		assert_eq!(tracer.drain(), expected_trace);

 		let expected_vm_trace = VMTrace {
 			parent_step: 0,
@ -887,7 +942,7 @@ mod tests {
 			}),
 		}];

-		assert_eq!(tracer.traces(), expected_trace);
+		assert_eq!(tracer.drain(), expected_trace);

 		let expected_vm_trace = VMTrace {
 			parent_step: 0,
@ -1138,7 +1193,7 @@ mod tests {

 		let executed = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			let opts = TransactOptions { check_nonce: true, tracing: false, vm_tracing: false };
+			let opts = TransactOptions::with_no_tracing();
 			ex.transact(&t, opts).unwrap()
 		};

@ -1175,7 +1230,7 @@ mod tests {

 		let res = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			let opts = TransactOptions { check_nonce: true, tracing: false, vm_tracing: false };
+			let opts = TransactOptions::with_no_tracing();
 			ex.transact(&t, opts)
 		};

@ -1208,7 +1263,7 @@ mod tests {

 		let res = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			let opts = TransactOptions { check_nonce: true, tracing: false, vm_tracing: false };
+			let opts = TransactOptions::with_no_tracing();
 			ex.transact(&t, opts)
 		};

@ -1241,7 +1296,7 @@ mod tests {

 		let res = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			let opts = TransactOptions { check_nonce: true, tracing: false, vm_tracing: false };
+			let opts = TransactOptions::with_no_tracing();
 			ex.transact(&t, opts)
 		};

--- a/ethcore/src/json_tests/state.rs
+++ b/ethcore/src/json_tests/state.rs
@ -15,23 +15,13 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

 use super::test_common::*;
-use tests::helpers::*;
 use pod_state::PodState;
-use ethereum;
-use spec::Spec;
+use trace;
+use client::{EvmTestClient, EvmTestError, TransactResult};
 use ethjson;
-use ethjson::state::test::ForkSpec;
 use transaction::SignedTransaction;
 use vm::EnvInfo;

-lazy_static! {
-	pub static ref FRONTIER: Spec = ethereum::new_frontier_test();
-	pub static ref HOMESTEAD: Spec = ethereum::new_homestead_test();
-	pub static ref EIP150: Spec = ethereum::new_eip150_test();
-	pub static ref EIP161: Spec = ethereum::new_eip161_test();
-	pub static ref _METROPOLIS: Spec = ethereum::new_metropolis_test();
-}
-
 pub fn json_chain_test(json_data: &[u8]) -> Vec<String> {
 	::ethcore_logger::init_log();
 	let tests = ethjson::state::test::Test::load(json_data).unwrap();
@ -43,35 +33,49 @@ pub fn json_chain_test(json_data: &[u8]) -> Vec<String> {
 			let env: EnvInfo = test.env.into();
 			let pre: PodState = test.pre_state.into();

-			for (spec, states) in test.post_states {
+			for (spec_name, states) in test.post_states {
 				let total = states.len();
-				let engine = match spec {
-					ForkSpec::Frontier => &FRONTIER.engine,
-					ForkSpec::Homestead => &HOMESTEAD.engine,
-					ForkSpec::EIP150 => &EIP150.engine,
-					ForkSpec::EIP158 => &EIP161.engine,
-					ForkSpec::Metropolis => continue,
+				let spec = match EvmTestClient::spec_from_json(&spec_name) {
+					Some(spec) => spec,
+					None => {
+						println!("   - {} | {:?} Ignoring tests because of missing spec", name, spec_name);
+						continue;
+					}
 				};

 				for (i, state) in states.into_iter().enumerate() {
-					let info = format!("   - {} | {:?} ({}/{}) ...", name, spec, i + 1, total);
+					let info = format!("   - {} | {:?} ({}/{}) ...", name, spec_name, i + 1, total);

 					let post_root: H256 = state.hash.into();
 					let transaction: SignedTransaction = multitransaction.select(&state.indexes).into();
-					let mut state = get_temp_state();
-					state.populate_from(pre.clone());
-					if transaction.verify_basic(true, None, env.number >= engine.params().eip86_transition).is_ok() {
-						state.commit().expect(&format!("State test {} failed due to internal error.", name));
-						let _res = state.apply(&env, &**engine, &transaction, false);
-					} else {
-						let _rest = state.commit();
-					}
-					if state.root() != &post_root {
-						println!("{} !!! State mismatch (got: {}, expect: {}", info, state.root(), post_root);
+
+					let result = || -> Result<_, EvmTestError> {
+						Ok(EvmTestClient::from_pod_state(spec, pre.clone())?
+							.transact(&env, transaction, trace::NoopVMTracer))
+					};
+					match result() {
+						Err(err) => {
+							println!("{} !!! Unexpected internal error: {:?}", info, err);
 							flushln!("{} fail", info);
 							failed.push(name.clone());
-					} else {
+						},
+						Ok(TransactResult::Ok { state_root, .. }) if state_root != post_root => {
+							println!("{} !!! State mismatch (got: {}, expect: {}", info, state_root, post_root);
+							flushln!("{} fail", info);
+							failed.push(name.clone());
+						},
+						Ok(TransactResult::Err { state_root, ref error }) if state_root != post_root => {
+							println!("{} !!! State mismatch (got: {}, expect: {}", info, state_root, post_root);
+							println!("{} !!! Execution error: {:?}", info, error);
+							flushln!("{} fail", info);
+							failed.push(name.clone());
+						},
+						Ok(TransactResult::Err { error, .. }) => {
+							flushln!("{} ok ({:?})", info, error);
+						},
+						Ok(_) => {
 							flushln!("{} ok", info);
+						},
 					}
 				}
 			}
--- a/ethcore/src/miner/transaction_queue.rs
+++ b/ethcore/src/miner/transaction_queue.rs
@ -506,8 +506,6 @@ pub struct AccountDetails {
 	pub balance: U256,
 }

-/// Transactions with `gas > (gas_limit + gas_limit * Factor(in percents))` are not imported to the queue.
-const GAS_LIMIT_HYSTERESIS: usize = 200; // (100/GAS_LIMIT_HYSTERESIS) %
 /// Transaction with the same (sender, nonce) can be replaced only if
 /// `new_gas_price > old_gas_price + old_gas_price >> SHIFT`
 const GAS_PRICE_BUMP_SHIFT: usize = 3; // 2 = 25%, 3 = 12.5%, 4 = 6.25%
@ -570,8 +568,8 @@ pub struct TransactionQueue {
 	minimal_gas_price: U256,
 	/// The maximum amount of gas any individual transaction may use.
 	tx_gas_limit: U256,
-	/// Current gas limit (block gas limit * factor). Transactions above the limit will not be accepted (default to !0)
-	total_gas_limit: U256,
+	/// Current gas limit (block gas limit). Transactions above the limit will not be accepted (default to !0)
+	block_gas_limit: U256,
 	/// Maximal time transaction may occupy the queue.
 	/// When we reach `max_time_in_queue / 2^3` we re-validate
 	/// account balance.
@ -631,7 +629,7 @@ impl TransactionQueue {
 		TransactionQueue {
 			strategy,
 			minimal_gas_price: U256::zero(),
-			total_gas_limit: !U256::zero(),
+			block_gas_limit: !U256::zero(),
 			tx_gas_limit,
 			max_time_in_queue: DEFAULT_QUEUING_PERIOD,
 			current,
@ -674,16 +672,10 @@ impl TransactionQueue {
 		self.current.gas_price_entry_limit()
 	}

-	/// Sets new gas limit. Transactions with gas slightly (`GAS_LIMIT_HYSTERESIS`) above the limit won't be imported.
+	/// Sets new gas limit. Transactions with gas over the limit will not be accepted.
 	/// Any transaction already imported to the queue is not affected.
 	pub fn set_gas_limit(&mut self, gas_limit: U256) {
-		let extra = gas_limit / U256::from(GAS_LIMIT_HYSTERESIS);
-
-		let total_gas_limit = match gas_limit.overflowing_add(extra) {
-			(_, true) => !U256::zero(),
-			(val, false) => val,
-		};
-		self.total_gas_limit = total_gas_limit;
+		self.block_gas_limit = gas_limit;
 	}

 	/// Sets new total gas limit.
@ -819,13 +811,13 @@ impl TransactionQueue {
 			}));
 		}

-		let gas_limit = cmp::min(self.tx_gas_limit, self.total_gas_limit);
+		let gas_limit = cmp::min(self.tx_gas_limit, self.block_gas_limit);
 		if tx.gas > gas_limit {
 			trace!(target: "txqueue",
 				"Dropping transaction above gas limit: {:?} ({} > min({}, {}))",
 				tx.hash(),
 				tx.gas,
-				self.total_gas_limit,
+				self.block_gas_limit,
 				self.tx_gas_limit
 			);
 			return Err(Error::Transaction(TransactionError::GasLimitExceeded {
@ -1922,13 +1914,13 @@ pub mod test {
 		// given
 		let mut txq = TransactionQueue::default();
 		txq.set_gas_limit(U256::zero());
-		assert_eq!(txq.total_gas_limit, U256::zero());
+		assert_eq!(txq.block_gas_limit, U256::zero());

 		// when
 		txq.set_gas_limit(!U256::zero());

 		// then
-		assert_eq!(txq.total_gas_limit, !U256::zero());
+		assert_eq!(txq.block_gas_limit, !U256::zero());
 	}

 	#[test]
@ -1945,7 +1937,7 @@ pub mod test {

 		// then
 		assert_eq!(unwrap_tx_err(res), TransactionError::GasLimitExceeded {
-			limit: U256::from(50_250), // Should be 100.5% of set_gas_limit
+			limit: U256::from(50_000),
 			got: gas,
 		});
 		let stats = txq.status();
--- a/ethcore/src/state/mod.rs
+++ b/ethcore/src/state/mod.rs
@ -31,7 +31,7 @@ use vm::EnvInfo;
 use error::Error;
 use executive::{Executive, TransactOptions};
 use factory::Factories;
-use trace::FlatTrace;
+use trace::{self, FlatTrace, VMTrace};
 use pod_account::*;
 use pod_state::{self, PodState};
 use types::basic_account::BasicAccount;
@ -59,8 +59,12 @@ pub use self::substate::Substate;
 pub struct ApplyOutcome {
 	/// The receipt for the applied transaction.
 	pub receipt: Receipt,
-	/// The trace for the applied transaction, if None if tracing is disabled.
+	/// The output of the applied transaction.
+	pub output: Bytes,
+	/// The trace for the applied transaction, empty if tracing was not produced.
 	pub trace: Vec<FlatTrace>,
+	/// The VM trace for the applied transaction, None if tracing was not produced.
+	pub vm_trace: Option<VMTrace>
 }

 /// Result type for the execution ("application") of a transaction.
@ -205,7 +209,7 @@ pub fn check_proof(
 		Err(_) => return ProvedExecution::BadProof,
 	};

-	match state.execute(env_info, engine, transaction, false, true) {
+	match state.execute(env_info, engine, transaction, TransactOptions::with_no_tracing(), true) {
 		Ok(executed) => ProvedExecution::Complete(executed),
 		Err(ExecutionError::Internal(_)) => ProvedExecution::BadProof,
 		Err(e) => ProvedExecution::Failed(e),
@ -290,7 +294,7 @@ const SEC_TRIE_DB_UNWRAP_STR: &'static str = "A state can only be created with v

 impl<B: Backend> State<B> {
 	/// Creates new state with empty state root
-	#[cfg(test)]
+	/// Used for tests.
 	pub fn new(mut db: B, account_start_nonce: U256, factories: Factories) -> State<B> {
 		let mut root = H256::new();
 		{
@ -623,29 +627,57 @@ impl<B: Backend> State<B> {
 	/// Execute a given transaction, producing a receipt and an optional trace.
 	/// This will change the state accordingly.
 	pub fn apply(&mut self, env_info: &EnvInfo, engine: &Engine, t: &SignedTransaction, tracing: bool) -> ApplyResult {
-//		let old = self.to_pod();
+		if tracing {
+			let options = TransactOptions::with_tracing();
+			self.apply_with_tracing(env_info, engine, t, options.tracer, options.vm_tracer)
+		} else {
+			let options = TransactOptions::with_no_tracing();
+			self.apply_with_tracing(env_info, engine, t, options.tracer, options.vm_tracer)
+		}
+	}
+
+	/// Execute a given transaction with given tracer and VM tracer producing a receipt and an optional trace.
+	/// This will change the state accordingly.
+	pub fn apply_with_tracing<V, T>(
+		&mut self,
+		env_info: &EnvInfo,
+		engine: &Engine,
+		t: &SignedTransaction,
+		tracer: T,
+		vm_tracer: V,
+	) -> ApplyResult where
+		T: trace::Tracer,
+		V: trace::VMTracer,
+	{
+		let options = TransactOptions::new(tracer, vm_tracer);
+		let e = self.execute(env_info, engine, t, options, false)?;

-		let e = self.execute(env_info, engine, t, tracing, false)?;
-//		trace!("Applied transaction. Diff:\n{}\n", state_diff::diff_pod(&old, &self.to_pod()));
 		let state_root = if env_info.number < engine.params().eip98_transition || env_info.number < engine.params().validate_receipts_transition {
 			self.commit()?;
 			Some(self.root().clone())
 		} else {
 			None
 		};
+
+		let output = e.output;
 		let receipt = Receipt::new(state_root, e.cumulative_gas_used, e.logs);
 		trace!(target: "state", "Transaction receipt: {:?}", receipt);
-		Ok(ApplyOutcome{receipt: receipt, trace: e.trace})
+
+		Ok(ApplyOutcome {
+			receipt,
+			output,
+			trace: e.trace,
+			vm_trace: e.vm_trace,
+		})
 	}

 	// Execute a given transaction without committing changes.
 	//
 	// `virt` signals that we are executing outside of a block set and restrictions like
 	// gas limits and gas costs should be lifted.
-	fn execute(&mut self, env_info: &EnvInfo, engine: &Engine, t: &SignedTransaction, tracing: bool, virt: bool)
-		-> Result<Executed, ExecutionError>
+	fn execute<T, V>(&mut self, env_info: &EnvInfo, engine: &Engine, t: &SignedTransaction, options: TransactOptions<T, V>, virt: bool)
+		-> Result<Executed, ExecutionError> where T: trace::Tracer, V: trace::VMTracer,
 	{
-		let options = TransactOptions { tracing: tracing, vm_tracing: false, check_nonce: true };
 		let mut e = Executive::new(self, env_info, engine);

 		match virt {
@ -730,9 +762,8 @@ impl<B: Backend> State<B> {
 		Ok(())
 	}

-	#[cfg(test)]
-	#[cfg(feature = "json-tests")]
 	/// Populate the state from `accounts`.
+	/// Used for tests.
 	pub fn populate_from(&mut self, accounts: PodState) {
 		assert!(self.checkpoints.borrow().is_empty());
 		for (add, acc) in accounts.drain().into_iter() {
--- a/ethcore/src/tests/client.rs
+++ b/ethcore/src/tests/client.rs
@ -19,7 +19,7 @@ use std::sync::Arc;
 use io::IoChannel;
 use client::{BlockChainClient, MiningBlockChainClient, Client, ClientConfig, BlockId};
 use state::{self, State, CleanupMode};
-use executive::Executive;
+use executive::{Executive, TransactOptions};
 use ethereum;
 use block::IsBlock;
 use tests::helpers::*;
@ -361,7 +361,7 @@ fn transaction_proof() {

 	let mut state = State::from_existing(backend, root, 0.into(), factories.clone()).unwrap();
 	Executive::new(&mut state, &client.latest_env_info(), &*test_spec.engine)
-		.transact(&transaction, Default::default()).unwrap();
+		.transact(&transaction, TransactOptions::with_no_tracing().dont_check_nonce()).unwrap();

 	assert_eq!(state.balance(&Address::default()).unwrap(), 5.into());
 	assert_eq!(state.balance(&address).unwrap(), 95.into());
--- a/ethcore/src/trace/executive_tracer.rs
+++ b/ethcore/src/trace/executive_tracer.rs
@ -167,7 +167,7 @@ impl Tracer for ExecutiveTracer {
 		ExecutiveTracer::default()
 	}

-	fn traces(self) -> Vec<FlatTrace> {
+	fn drain(self) -> Vec<FlatTrace> {
 		self.traces
 	}
 }
--- a/ethcore/src/trace/mod.rs
+++ b/ethcore/src/trace/mod.rs
@ -85,7 +85,7 @@ pub trait Tracer: Send {
 	fn subtracer(&self) -> Self where Self: Sized;

 	/// Consumes self and returns all traces.
-	fn traces(self) -> Vec<FlatTrace>;
+	fn drain(self) -> Vec<FlatTrace>;
 }

 /// Used by executive to build VM traces.
--- a/ethcore/src/trace/noop_tracer.rs
+++ b/ethcore/src/trace/noop_tracer.rs
@ -62,7 +62,7 @@ impl Tracer for NoopTracer {
 		NoopTracer
 	}

-	fn traces(self) -> Vec<FlatTrace> {
+	fn drain(self) -> Vec<FlatTrace> {
 		vec![]
 	}
 }
--- a/ethcore/vm/src/tests.rs
+++ b/ethcore/vm/src/tests.rs
@ -61,6 +61,7 @@ pub struct FakeExt {
 	pub info: EnvInfo,
 	pub schedule: Schedule,
 	pub balances: HashMap<Address, U256>,
+	pub tracing: bool,
 }

 // similar to the normal `finalize` function, but ignoring NeedsReturn.
@ -184,4 +185,8 @@ impl Ext for FakeExt {
 	fn inc_sstore_clears(&mut self) {
 		self.sstore_clears += 1;
 	}
+
+	fn trace_next_instruction(&mut self, _pc: usize, _instruction: u8) -> bool {
+		self.tracing
+	}
 }
--- a/ethcore/wasm/src/tests.rs
+++ b/ethcore/wasm/src/tests.rs
@ -415,36 +415,121 @@ fn storage_read() {
 	assert_eq!(Address::from(&result[12..32]), address);
 }

-
-// Tests that contract's ability to read from a storage
-// Test prepopulates address into storage, than executes a contract which read that address from storage and write this address into result
-#[test]
-fn math_add() {
+macro_rules! reqrep_test {
+	($name: expr, $input: expr) => {
+		{
 			::ethcore_logger::init_log();
-	let code = load_sample!("math.wasm");
+			let code = load_sample!($name);

 			let mut params = ActionParams::default();
 			params.gas = U256::from(100_000);
 			params.code = Some(Arc::new(code));
-
-	let mut args = [0u8; 64];
-	let arg_a = U256::from_dec_str("999999999999999999999999999999").unwrap();
-	let arg_b = U256::from_dec_str("888888888888888888888888888888").unwrap();
-	arg_a.to_big_endian(&mut args[0..32]);
-	arg_b.to_big_endian(&mut args[32..64]);
-	params.data = Some(args.to_vec());
+			params.data = Some($input);

 			let (gas_left, result) = {
 				let mut interpreter = wasm_interpreter();
 				let result = interpreter.exec(params, &mut FakeExt::new()).expect("Interpreter to execute without any errors");
 				match result {
-				GasLeft::Known(_) => { panic!("storage_read should return payload"); },
+						GasLeft::Known(_) => { panic!("Test is expected to return payload to check"); },
 						GasLeft::NeedsReturn { gas_left: gas, data: result, apply_state: _apply } => (gas, result.to_vec()),
 				}
 			};

-	let sum: U256 = (&result[..]).into();
-
-	assert_eq!(gas_left, U256::from(96284));
-	assert_eq!(sum, U256::from_dec_str("1888888888888888888888888888887").unwrap());
+			(gas_left, result)
+		}
+	}
+}
+
+// math_* tests check the ability of wasm contract to perform big integer operations
+// - addition
+// - multiplication
+// - substraction
+// - division
+
+// addition
+#[test]
+fn math_add() {
+
+	let (gas_left, result) = reqrep_test!(
+		"math.wasm",
+		{
+			let mut args = [0u8; 65];
+			let arg_a = U256::from_dec_str("999999999999999999999999999999").unwrap();
+			let arg_b = U256::from_dec_str("888888888888888888888888888888").unwrap();
+			arg_a.to_big_endian(&mut args[1..33]);
+			arg_b.to_big_endian(&mut args[33..65]);
+			args.to_vec()
+		}
+	);
+
+	assert_eq!(gas_left, U256::from(98087));
+	assert_eq!(
+		U256::from_dec_str("1888888888888888888888888888887").unwrap(),
+		(&result[..]).into()
+	);
+}
+
+// multiplication
+#[test]
+fn math_mul() {
+	let (gas_left, result) = reqrep_test!(
+		"math.wasm",
+		{
+			let mut args = [1u8; 65];
+			let arg_a = U256::from_dec_str("888888888888888888888888888888").unwrap();
+			let arg_b = U256::from_dec_str("999999999999999999999999999999").unwrap();
+			arg_a.to_big_endian(&mut args[1..33]);
+			arg_b.to_big_endian(&mut args[33..65]);
+			args.to_vec()
+		}
+	);
+
+	assert_eq!(gas_left, U256::from(97236));
+	assert_eq!(
+		U256::from_dec_str("888888888888888888888888888887111111111111111111111111111112").unwrap(),
+		(&result[..]).into()
+	);
+}
+
+// substraction
+#[test]
+fn math_sub() {
+	let (gas_left, result) = reqrep_test!(
+		"math.wasm",
+		{
+			let mut args = [2u8; 65];
+			let arg_a = U256::from_dec_str("999999999999999999999999999999").unwrap();
+			let arg_b = U256::from_dec_str("888888888888888888888888888888").unwrap();
+			arg_a.to_big_endian(&mut args[1..33]);
+			arg_b.to_big_endian(&mut args[33..65]);
+			args.to_vec()
+		}
+	);
+
+	assert_eq!(gas_left, U256::from(98131));
+	assert_eq!(
+		U256::from_dec_str("111111111111111111111111111111").unwrap(),
+		(&result[..]).into()
+	);
+}
+
+#[test]
+fn math_div() {
+	let (gas_left, result) = reqrep_test!(
+		"math.wasm",
+		{
+			let mut args = [3u8; 65];
+			let arg_a = U256::from_dec_str("999999999999999999999999999999").unwrap();
+			let arg_b = U256::from_dec_str("888888888888888888888888").unwrap();
+			arg_a.to_big_endian(&mut args[1..33]);
+			arg_b.to_big_endian(&mut args[33..65]);
+			args.to_vec()
+		}
+	);
+
+	assert_eq!(gas_left, U256::from(91420));
+	assert_eq!(
+		U256::from_dec_str("1125000").unwrap(),
+		(&result[..]).into()
+	);
 }
--- a/evmbin/Cargo.toml
+++ b/evmbin/Cargo.toml
@ -14,6 +14,7 @@ docopt = "0.8"
 serde = "1.0"
 serde_derive = "1.0"
 ethcore = { path = "../ethcore" }
+ethjson = { path = "../json" }
 ethcore-util = { path = "../util" }
 evm = { path = "../ethcore/evm" }
 vm = { path = "../ethcore/vm" }
--- a/evmbin/src/display/json.rs
+++ b/evmbin/src/display/json.rs
@ -30,10 +30,8 @@ pub struct Informant {
 	depth: usize,
 	pc: usize,
 	instruction: u8,
-	name: &'static str,
 	gas_cost: U256,
 	gas_used: U256,
-	stack_pop: usize,
 	stack: Vec<U256>,
 	memory: Vec<u8>,
 	storage: HashMap<H256, H256>,
@ -58,11 +56,19 @@ impl Informant {
 }

 impl vm::Informant for Informant {
+	fn before_test(&self, name: &str, action: &str) {
+		println!(
+			"{{\"test\":\"{name}\",\"action\":\"{action}\"}}",
+			name = name,
+			action = action,
+		);
+	}
+
 	fn set_gas(&mut self, gas: U256) {
 		self.gas_used = gas;
 	}

-	fn finish(&mut self, result: Result<vm::Success, vm::Failure>) {
+	fn finish(result: Result<vm::Success, vm::Failure>) {
 		match result {
 			Ok(success) => println!(
 				"{{\"output\":\"0x{output}\",\"gasUsed\":\"{gas:x}\",\"time\":{time}}}",
@ -112,7 +118,7 @@ impl trace::VMTracer for Informant {
 		self.gas_used = gas_used;

 		let len = self.stack.len();
-		self.stack.truncate(len - info.args);
+		self.stack.truncate(if len > info.args { len - info.args } else { 0 });
 		self.stack.extend_from_slice(stack_push);

 		if let Some((pos, data)) = mem_diff {
--- a/evmbin/src/display/simple.rs
+++ b/evmbin/src/display/simple.rs
@ -27,7 +27,11 @@ use info as vm;
 pub struct Informant;

 impl vm::Informant for Informant {
-	fn finish(&mut self, result: Result<vm::Success, vm::Failure>) {
+	fn before_test(&self, name: &str, action: &str) {
+		println!("Test: {} ({})", name, action);
+	}
+
+	fn finish(result: Result<vm::Success, vm::Failure>) {
 		match result {
 			Ok(success) => {
 				println!("Output: 0x{}", success.output.to_hex());
--- a/evmbin/src/info.rs
+++ b/evmbin/src/info.rs
@ -17,17 +17,19 @@
 //! VM runner.

 use std::time::{Instant, Duration};
-use util::U256;
-use ethcore::{trace, spec};
-use ethcore::client::{EvmTestClient, EvmTestError};
-use vm::ActionParams;
+use util::{U256, H256};
+use ethcore::{trace, spec, transaction, pod_state};
+use ethcore::client::{self, EvmTestClient, EvmTestError, TransactResult};
+use ethjson;

 /// VM execution informant
 pub trait Informant: trace::VMTracer {
+	/// Display a single run init message
+	fn before_test(&self, test: &str, action: &str);
 	/// Set initial gas.
 	fn set_gas(&mut self, _gas: U256) {}
 	/// Display final result.
-	fn finish(&mut self, result: Result<Success, Failure>);
+	fn finish(result: Result<Success, Failure>);
 }

 /// Execution finished correctly
@ -50,17 +52,71 @@ pub struct Failure {
 	pub time: Duration,
 }

+/// Execute given Transaction and verify resulting state root.
+pub fn run_transaction<T: Informant>(
+	name: &str,
+	idx: usize,
+	spec: &ethjson::state::test::ForkSpec,
+	pre_state: &pod_state::PodState,
+	post_root: H256,
+	env_info: &client::EnvInfo,
+	transaction: transaction::SignedTransaction,
+	mut informant: T,
+) {
+	let spec_name = format!("{:?}", spec).to_lowercase();
+	let spec = match EvmTestClient::spec_from_json(spec) {
+		Some(spec) => {
+			informant.before_test(&format!("{}:{}:{}", name, spec_name, idx), "starting");
+			spec
+		},
+		None => {
+			informant.before_test(&format!("{}:{}:{}", name, spec_name, idx), "skipping because of missing spec");
+			return;
+		},
+	};
+
+	informant.set_gas(env_info.gas_limit);
+
+	let result = run(spec, env_info.gas_limit, pre_state, |mut client| {
+		let result = client.transact(env_info, transaction, informant);
+		match result {
+			TransactResult::Ok { state_root, .. } if state_root != post_root => {
+				Err(EvmTestError::PostCondition(format!(
+					"State root mismatch (got: {}, expected: {})",
+					state_root,
+					post_root,
+				)))
+			},
+			TransactResult::Ok { gas_left, output, .. } => {
+				Ok((gas_left, output))
+			},
+			TransactResult::Err { error, .. } => {
+				Err(EvmTestError::PostCondition(format!(
+					"Unexpected execution error: {:?}", error
+				)))
+			},
+		}
+	});
+
+	T::finish(result)
+}
+
 /// Execute VM with given `ActionParams`
-pub fn run<T: trace::VMTracer>(vm_tracer: &mut T, spec: spec::Spec, params: ActionParams) -> Result<Success, Failure> {
-	let mut test_client = EvmTestClient::new(spec).map_err(|error| Failure {
+pub fn run<'a, F, T>(spec: &'a spec::Spec, initial_gas: U256, pre_state: T, run: F) -> Result<Success, Failure> where
+	F: FnOnce(EvmTestClient) -> Result<(U256, Vec<u8>), EvmTestError>,
+	T: Into<Option<&'a pod_state::PodState>>,
+{
+	let test_client = match pre_state.into() {
+		Some(pre_state) => EvmTestClient::from_pod_state(spec, pre_state.clone()),
+		None => EvmTestClient::new(spec),
+	}.map_err(|error| Failure {
 		gas_used: 0.into(),
 		error,
 		time: Duration::from_secs(0)
 	})?;

-	let initial_gas = params.gas;
 	let start = Instant::now();
-	let result = test_client.call(params, vm_tracer);
+	let result = run(test_client);
 	let duration = start.elapsed();

 	match result {
--- a/evmbin/src/main.rs
+++ b/evmbin/src/main.rs
@ -17,8 +17,9 @@
 //! Parity EVM interpreter binary.

 #![warn(missing_docs)]
-#![allow(dead_code)]
+
 extern crate ethcore;
+extern crate ethjson;
 extern crate rustc_hex;
 extern crate serde;
 #[macro_use]
@ -31,6 +32,7 @@ extern crate panic_hook;

 use std::sync::Arc;
 use std::{fmt, fs};
+use std::path::PathBuf;
 use docopt::Docopt;
 use rustc_hex::FromHex;
 use util::{U256, Bytes, Address};
@ -47,6 +49,7 @@ EVM implementation for Parity.
  Copyright 2016, 2017 Parity Technologies (UK) Ltd

 Usage:
+    parity-evm state-test <file> [--json --only NAME --chain CHAIN]
    parity-evm stats [options]
    parity-evm [options]
    parity-evm [-h | --help]
@ -59,6 +62,10 @@ Transaction options:
    --gas GAS          Supplied gas as hex (without 0x).
    --gas-price WEI    Supplied gas price as hex (without 0x).

+State test options:
+    --only NAME        Runs only a single test matching the name.
+    --chain CHAIN      Run only tests from specific chain.
+
 General options:
    --json             Display verbose results in JSON.
    --chain CHAIN      Chain spec file path.
@ -71,20 +78,67 @@ fn main() {

 	let args: Args = Docopt::new(USAGE).and_then(|d| d.deserialize()).unwrap_or_else(|e| e.exit());

-	if args.flag_json {
-		run(args, display::json::Informant::default())
+	if args.cmd_state_test {
+		run_state_test(args)
+	} else if args.flag_json {
+		run_call(args, display::json::Informant::default())
 	} else {
-		run(args, display::simple::Informant::default())
+		run_call(args, display::simple::Informant::default())
 	}
 }

-fn run<T: Informant>(args: Args, mut informant: T) {
+fn run_state_test(args: Args) {
+	use ethjson::state::test::Test;
+
+	let file = args.arg_file.expect("FILE is required");
+	let mut file = match fs::File::open(&file) {
+		Err(err) => die(format!("Unable to open: {:?}: {}", file, err)),
+		Ok(file) => file,
+	};
+	let state_test = match Test::load(&mut file) {
+		Err(err) => die(format!("Unable to load the test file: {}", err)),
+		Ok(test) => test,
+	};
+	let only_test = args.flag_only.map(|s| s.to_lowercase());
+	let only_chain = args.flag_chain.map(|s| s.to_lowercase());
+
+	for (name, test) in state_test {
+		if let Some(false) = only_test.as_ref().map(|only_test| &name.to_lowercase() == only_test) {
+			continue;
+		}
+
+		let multitransaction = test.transaction;
+		let env_info = test.env.into();
+		let pre = test.pre_state.into();
+
+		for (spec, states) in test.post_states {
+			if let Some(false) = only_chain.as_ref().map(|only_chain| &format!("{:?}", spec).to_lowercase() == only_chain) {
+				continue;
+			}
+
+			for (idx, state) in states.into_iter().enumerate() {
+				let post_root = state.hash.into();
+				let transaction = multitransaction.select(&state.indexes).into();
+
+				if args.flag_json {
+					let i = display::json::Informant::default();
+					info::run_transaction(&name, idx, &spec, &pre, post_root, &env_info, transaction, i)
+				} else {
+					let i = display::simple::Informant::default();
+					info::run_transaction(&name, idx, &spec, &pre, post_root, &env_info, transaction, i)
+				}
+			}
+		}
+	}
+}
+
+fn run_call<T: Informant>(args: Args, mut informant: T) {
 	let from = arg(args.from(), "--from");
 	let to = arg(args.to(), "--to");
 	let code = arg(args.code(), "--code");
 	let spec = arg(args.spec(), "--chain");
 	let gas = arg(args.gas(), "--gas");
-	let gas_price = arg(args.gas(), "--gas-price");
+	let gas_price = arg(args.gas_price(), "--gas-price");
 	let data = arg(args.data(), "--input");

 	if code.is_none() && to == Address::default() {
@ -103,13 +157,18 @@ fn run<T: Informant>(args: Args, mut informant: T) {
 	params.data = data;

 	informant.set_gas(gas);
-	let result = info::run(&mut informant, spec, params);
-	informant.finish(result);
+	let result = info::run(&spec, gas, None, |mut client| {
+		client.call(params, &mut informant)
+	});
+	T::finish(result);
 }

 #[derive(Debug, Deserialize)]
 struct Args {
 	cmd_stats: bool,
+	cmd_state_test: bool,
+	arg_file: Option<PathBuf>,
+	flag_only: Option<String>,
 	flag_from: Option<String>,
 	flag_to: Option<String>,
 	flag_code: Option<String>,
@ -221,4 +280,22 @@ mod tests {
 		assert_eq!(args.data(), Ok(Some(vec![06])));
 		assert_eq!(args.flag_chain, Some("./testfile".to_owned()));
 	}
+
+	#[test]
+	fn should_parse_state_test_command() {
+		let args = run(&[
+			"parity-evm",
+			"state-test",
+			"./file.json",
+			"--chain", "homestead",
+			"--only=add11",
+			"--json",
+		]);
+
+		assert_eq!(args.cmd_state_test, true);
+		assert!(args.arg_file.is_some());
+		assert_eq!(args.flag_json, true);
+		assert_eq!(args.flag_chain, Some("homestead".to_owned()));
+		assert_eq!(args.flag_only, Some("add11".to_owned()));
+	}
 }
--- a/ipfs/src/route.rs
+++ b/ipfs/src/route.rs
@ -119,7 +119,7 @@ mod tests {
 	use ethcore::client::TestBlockChainClient;

 	fn get_mocked_handler() -> IpfsHandler {
-		IpfsHandler::new(None, None, Arc::new(TestBlockChainClient::new()))
+		IpfsHandler::new(None.into(), None.into(), Arc::new(TestBlockChainClient::new()))
 	}

 	#[test]
--- a/js/src/api/rpc/parity/parity.js
+++ b/js/src/api/rpc/parity/parity.js
@ -385,6 +385,11 @@ export default class Parity {
      .then(outNumber);
  }

+  nodeHealth () {
+    return this._transport
+      .execute('parity_nodeHealth');
+  }
+
  nodeName () {
    return this._transport
      .execute('parity_nodeName');
--- a/js/src/redux/providers/status.js
+++ b/js/src/redux/providers/status.js
@ -200,7 +200,7 @@ export default class Status {
    const statusPromises = [
      this._api.eth.syncing(),
      this._api.parity.netPeers(),
-      this._fetchHealth()
+      this._api.parity.nodeHealth()
    ];

    return Promise
@ -247,13 +247,6 @@ export default class Status {
    };
  }

-  _fetchHealth = () => {
-    // Support Parity-Extension.
-    const uiUrl = this._api.transport.uiUrlWithProtocol || '';
-
-    return fetch(`${uiUrl}/api/health`).then(res => res.json());
-  }
-
  /**
   * The data fetched here should not change
   * unless Parity is restarted. They are thus
--- a/json/src/state/test.rs
+++ b/json/src/state/test.rs
@ -104,7 +104,10 @@ pub enum ForkSpec {
 	EIP158,
 	Frontier,
 	Homestead,
+	// TODO [ToDr] Deprecated
 	Metropolis,
+	Byzantium,
+	Constantinople,
 }

 /// State test indexes deserialization.
--- a/parity/configuration.rs
+++ b/parity/configuration.rs
@ -346,6 +346,7 @@ impl Configuration {
 				daemon: daemon,
 				logger_config: logger_config.clone(),
 				miner_options: self.miner_options(self.args.flag_reseal_min_period)?,
+				ntp_servers: self.ntp_servers(),
 				ws_conf: ws_conf,
 				http_conf: http_conf,
 				ipc_conf: ipc_conf,
@ -563,7 +564,6 @@ impl Configuration {
 	fn ui_config(&self) -> UiConfiguration {
 		UiConfiguration {
 			enabled: self.ui_enabled(),
-			ntp_servers: self.ntp_servers(),
 			interface: self.ui_interface(),
 			port: self.ui_port(),
 			hosts: self.ui_hosts(),
@ -576,7 +576,6 @@ impl Configuration {

 		DappsConfiguration {
 			enabled: self.dapps_enabled(),
-			ntp_servers: self.ntp_servers(),
 			dapps_path: PathBuf::from(self.directories().dapps),
 			extra_dapps: if self.args.cmd_dapp {
 				self.args.arg_path.iter().map(|path| PathBuf::from(path)).collect()
@ -1318,12 +1317,6 @@ mod tests {
 			support_token_api: true
 		}, UiConfiguration {
 			enabled: true,
-			ntp_servers: vec![
-				"0.parity.pool.ntp.org:123".into(),
-				"1.parity.pool.ntp.org:123".into(),
-				"2.parity.pool.ntp.org:123".into(),
-				"3.parity.pool.ntp.org:123".into(),
-			],
 			interface: "127.0.0.1".into(),
 			port: 8180,
 			hosts: Some(vec![]),
@ -1348,6 +1341,12 @@ mod tests {
 			daemon: None,
 			logger_config: Default::default(),
 			miner_options: Default::default(),
+			ntp_servers: vec![
+				"0.parity.pool.ntp.org:123".into(),
+				"1.parity.pool.ntp.org:123".into(),
+				"2.parity.pool.ntp.org:123".into(),
+				"3.parity.pool.ntp.org:123".into(),
+			],
 			ws_conf: Default::default(),
 			http_conf: Default::default(),
 			ipc_conf: Default::default(),
@ -1567,16 +1566,9 @@ mod tests {
 		let conf3 = parse(&["parity", "--ui-path", "signer", "--ui-interface", "test"]);

 		// then
-		let ntp_servers = vec![
-			"0.parity.pool.ntp.org:123".into(),
-			"1.parity.pool.ntp.org:123".into(),
-			"2.parity.pool.ntp.org:123".into(),
-			"3.parity.pool.ntp.org:123".into(),
-		];
 		assert_eq!(conf0.directories().signer, "signer".to_owned());
 		assert_eq!(conf0.ui_config(), UiConfiguration {
 			enabled: true,
-			ntp_servers: ntp_servers.clone(),
 			interface: "127.0.0.1".into(),
 			port: 8180,
 			hosts: Some(vec![]),
@ -1585,7 +1577,6 @@ mod tests {
 		assert_eq!(conf1.directories().signer, "signer".to_owned());
 		assert_eq!(conf1.ui_config(), UiConfiguration {
 			enabled: true,
-			ntp_servers: ntp_servers.clone(),
 			interface: "127.0.0.1".into(),
 			port: 8180,
 			hosts: Some(vec![]),
@ -1595,7 +1586,6 @@ mod tests {
 		assert_eq!(conf2.directories().signer, "signer".to_owned());
 		assert_eq!(conf2.ui_config(), UiConfiguration {
 			enabled: true,
-			ntp_servers: ntp_servers.clone(),
 			interface: "127.0.0.1".into(),
 			port: 3123,
 			hosts: Some(vec![]),
@ -1604,7 +1594,6 @@ mod tests {
 		assert_eq!(conf3.directories().signer, "signer".to_owned());
 		assert_eq!(conf3.ui_config(), UiConfiguration {
 			enabled: true,
-			ntp_servers: ntp_servers.clone(),
 			interface: "test".into(),
 			port: 8180,
 			hosts: Some(vec![]),
--- a/parity/dapps.rs
+++ b/parity/dapps.rs
@ -22,12 +22,12 @@ use ethcore::client::{Client, BlockChainClient, BlockId};
 use ethcore::transaction::{Transaction, Action};
 use ethsync::LightSync;
 use futures::{future, IntoFuture, Future, BoxFuture};
-use futures_cpupool::CpuPool;
 use hash_fetch::fetch::Client as FetchClient;
 use hash_fetch::urlhint::ContractClient;
 use helpers::replace_home;
 use light::client::Client as LightClient;
 use light::on_demand::{self, OnDemand};
+use node_health::{SyncStatus, NodeHealth};
 use rpc;
 use rpc_apis::SignerService;
 use parity_reactor;
@ -36,7 +36,6 @@ use util::{Bytes, Address};
 #[derive(Debug, PartialEq, Clone)]
 pub struct Configuration {
 	pub enabled: bool,
-	pub ntp_servers: Vec<String>,
 	pub dapps_path: PathBuf,
 	pub extra_dapps: Vec<PathBuf>,
 	pub extra_embed_on: Vec<(String, u16)>,
@ -48,12 +47,6 @@ impl Default for Configuration {
 		let data_dir = default_data_path();
 		Configuration {
 			enabled: true,
-			ntp_servers: vec![
-				"0.parity.pool.ntp.org:123".into(),
-				"1.parity.pool.ntp.org:123".into(),
-				"2.parity.pool.ntp.org:123".into(),
-				"3.parity.pool.ntp.org:123".into(),
-			],
 			dapps_path: replace_home(&data_dir, "$BASE/dapps").into(),
 			extra_dapps: vec![],
 			extra_embed_on: vec![],
@ -149,10 +142,10 @@ impl ContractClient for LightRegistrar {
 // to resolve.
 #[derive(Clone)]
 pub struct Dependencies {
+	pub node_health: NodeHealth,
 	pub sync_status: Arc<SyncStatus>,
 	pub contract_client: Arc<ContractClient>,
 	pub remote: parity_reactor::TokioRemote,
-	pub pool: CpuPool,
 	pub fetch: FetchClient,
 	pub signer: Arc<SignerService>,
 	pub ui_address: Option<(String, u16)>,
@ -165,7 +158,6 @@ pub fn new(configuration: Configuration, deps: Dependencies) -> Result<Option<Mi

 	server::dapps_middleware(
 		deps,
-		&configuration.ntp_servers,
 		configuration.dapps_path,
 		configuration.extra_dapps,
 		rpc::DAPPS_DOMAIN,
@ -174,19 +166,18 @@ pub fn new(configuration: Configuration, deps: Dependencies) -> Result<Option<Mi
 	).map(Some)
 }

-pub fn new_ui(enabled: bool, ntp_servers: &[String], deps: Dependencies) -> Result<Option<Middleware>, String> {
+pub fn new_ui(enabled: bool, deps: Dependencies) -> Result<Option<Middleware>, String> {
 	if !enabled {
 		return Ok(None);
 	}

 	server::ui_middleware(
 		deps,
-		ntp_servers,
 		rpc::DAPPS_DOMAIN,
 	).map(Some)
 }

-pub use self::server::{SyncStatus, Middleware, service};
+pub use self::server::{Middleware, service};

 #[cfg(not(feature = "dapps"))]
 mod server {
@ -196,11 +187,6 @@ mod server {
 	use parity_rpc::{hyper, RequestMiddleware, RequestMiddlewareAction};
 	use rpc_apis;

-	pub trait SyncStatus {
-		fn is_major_importing(&self) -> bool;
-		fn peers(&self) -> (usize, usize);
-	}
-
 	pub struct Middleware;
 	impl RequestMiddleware for Middleware {
 		fn on_request(
@ -212,7 +198,6 @@ mod server {

 	pub fn dapps_middleware(
 		_deps: Dependencies,
-		_ntp_servers: &[String],
 		_dapps_path: PathBuf,
 		_extra_dapps: Vec<PathBuf>,
 		_dapps_domain: &str,
@ -224,7 +209,6 @@ mod server {

 	pub fn ui_middleware(
 		_deps: Dependencies,
-		_ntp_servers: &[String],
 		_dapps_domain: &str,
 	) -> Result<Middleware, String> {
 		Err("Your Parity version has been compiled without UI support.".into())
@ -246,11 +230,9 @@ mod server {
 	use parity_reactor;

 	pub use parity_dapps::Middleware;
-	pub use parity_dapps::SyncStatus;

 	pub fn dapps_middleware(
 		deps: Dependencies,
-		ntp_servers: &[String],
 		dapps_path: PathBuf,
 		extra_dapps: Vec<PathBuf>,
 		dapps_domain: &str,
@ -262,8 +244,7 @@ mod server {
 		let web_proxy_tokens = Arc::new(move |token| signer.web_proxy_access_token_domain(&token));

 		Ok(parity_dapps::Middleware::dapps(
-			ntp_servers,
-			deps.pool,
+			deps.node_health,
 			parity_remote,
 			deps.ui_address,
 			extra_embed_on,
@ -280,13 +261,11 @@ mod server {

 	pub fn ui_middleware(
 		deps: Dependencies,
-		ntp_servers: &[String],
 		dapps_domain: &str,
 	) -> Result<Middleware, String> {
 		let parity_remote = parity_reactor::Remote::new(deps.remote.clone());
 		Ok(parity_dapps::Middleware::ui(
-			ntp_servers,
-			deps.pool,
+			deps.node_health,
 			parity_remote,
 			dapps_domain,
 			deps.contract_client,
--- a/parity/main.rs
+++ b/parity/main.rs
@ -58,6 +58,7 @@ extern crate ethcore_util as util;
 extern crate ethcore_network as network;
 extern crate ethkey;
 extern crate ethsync;
+extern crate node_health;
 extern crate panic_hook;
 extern crate parity_hash_fetch as hash_fetch;
 extern crate parity_ipfs_api;
--- a/parity/rpc.rs
+++ b/parity/rpc.rs
@ -73,7 +73,6 @@ impl Default for HttpConfiguration {
 #[derive(Debug, PartialEq, Clone)]
 pub struct UiConfiguration {
 	pub enabled: bool,
-	pub ntp_servers: Vec<String>,
 	pub interface: String,
 	pub port: u16,
 	pub hosts: Option<Vec<String>>,
@ -107,12 +106,6 @@ impl Default for UiConfiguration {
 	fn default() -> Self {
 		UiConfiguration {
 			enabled: true && cfg!(feature = "ui-enabled"),
-			ntp_servers: vec![
-				"0.parity.pool.ntp.org:123".into(),
-				"1.parity.pool.ntp.org:123".into(),
-				"2.parity.pool.ntp.org:123".into(),
-				"3.parity.pool.ntp.org:123".into(),
-			],
 			port: 8180,
 			interface: "127.0.0.1".into(),
 			hosts: Some(vec![]),
--- a/parity/rpc_apis.rs
+++ b/parity/rpc_apis.rs
@ -27,17 +27,18 @@ use ethcore::account_provider::AccountProvider;
 use ethcore::client::Client;
 use ethcore::miner::{Miner, ExternalMiner};
 use ethcore::snapshot::SnapshotService;
-use parity_rpc::{Metadata, NetworkSettings};
-use parity_rpc::informant::{ActivityNotifier, ClientNotifier};
-use parity_rpc::dispatch::{FullDispatcher, LightDispatcher};
+use ethcore_logger::RotatingLogger;
 use ethsync::{ManageNetwork, SyncProvider, LightSync};
 use hash_fetch::fetch::Client as FetchClient;
 use jsonrpc_core::{self as core, MetaIoHandler};
 use light::{TransactionQueue as LightTransactionQueue, Cache as LightDataCache};
+use node_health::NodeHealth;
+use parity_reactor;
+use parity_rpc::dispatch::{FullDispatcher, LightDispatcher};
+use parity_rpc::informant::{ActivityNotifier, ClientNotifier};
+use parity_rpc::{Metadata, NetworkSettings};
 use updater::Updater;
 use util::{Mutex, RwLock};
-use ethcore_logger::RotatingLogger;
-use parity_reactor;

 #[derive(Debug, PartialEq, Clone, Eq, Hash)]
 pub enum Api {
@ -217,6 +218,7 @@ pub struct FullDependencies {
 	pub settings: Arc<NetworkSettings>,
 	pub net_service: Arc<ManageNetwork>,
 	pub updater: Arc<Updater>,
+	pub health: NodeHealth,
 	pub geth_compatibility: bool,
 	pub dapps_service: Option<Arc<DappsService>>,
 	pub dapps_address: Option<(String, u16)>,
@ -300,12 +302,13 @@ impl FullDependencies {
 						false => None,
 					};
 					handler.extend_with(ParityClient::new(
-						&self.client,
-						&self.miner,
-						&self.sync,
-						&self.updater,
-						&self.net_service,
-						&self.secret_store,
+						self.client.clone(),
+						self.miner.clone(),
+						self.sync.clone(),
+						self.updater.clone(),
+						self.net_service.clone(),
+						self.health.clone(),
+						self.secret_store.clone(),
 						self.logger.clone(),
 						self.settings.clone(),
 						signer,
@ -403,6 +406,7 @@ pub struct LightDependencies {
 	pub secret_store: Arc<AccountProvider>,
 	pub logger: Arc<RotatingLogger>,
 	pub settings: Arc<NetworkSettings>,
+	pub health: NodeHealth,
 	pub on_demand: Arc<::light::on_demand::OnDemand>,
 	pub cache: Arc<Mutex<LightDataCache>>,
 	pub transaction_queue: Arc<RwLock<LightTransactionQueue>>,
@ -507,6 +511,7 @@ impl LightDependencies {
 						self.secret_store.clone(),
 						self.logger.clone(),
 						self.settings.clone(),
+						self.health.clone(),
 						signer,
 						self.dapps_address.clone(),
 						self.ws_address.clone(),
--- a/parity/run.rs
+++ b/parity/run.rs
@ -14,6 +14,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

+use std::fmt;
 use std::sync::Arc;
 use std::net::{TcpListener};

@ -32,6 +33,7 @@ use fdlimit::raise_fd_limit;
 use hash_fetch::fetch::{Fetch, Client as FetchClient};
 use informant::{Informant, LightNodeInformantData, FullNodeInformantData};
 use light::Cache as LightDataCache;
+use node_health;
 use parity_reactor::EventLoop;
 use parity_rpc::{NetworkSettings, informant, is_major_importing};
 use updater::{UpdatePolicy, Updater};
@ -80,6 +82,7 @@ pub struct RunCmd {
 	pub daemon: Option<String>,
 	pub logger_config: LogConfig,
 	pub miner_options: MinerOptions,
+	pub ntp_servers: Vec<String>,
 	pub ws_conf: rpc::WsConfiguration,
 	pub http_conf: rpc::HttpConfiguration,
 	pub ipc_conf: rpc::IpcConfiguration,
@ -283,7 +286,7 @@ fn execute_light(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) ->

 	// the dapps server
 	let signer_service = Arc::new(signer::new_service(&cmd.ws_conf, &cmd.ui_conf, &cmd.logger_config));
-	let dapps_deps = {
+	let (node_health, dapps_deps) = {
 		let contract_client = Arc::new(::dapps::LightRegistrar {
 			client: service.client().clone(),
 			sync: light_sync.clone(),
@ -291,7 +294,12 @@ fn execute_light(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) ->
 		});

 		struct LightSyncStatus(Arc<LightSync>);
-		impl dapps::SyncStatus for LightSyncStatus {
+		impl fmt::Debug for LightSyncStatus {
+			fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+				write!(fmt, "Light Sync Status")
+			}
+		}
+		impl node_health::SyncStatus for LightSyncStatus {
 			fn is_major_importing(&self) -> bool { self.0.is_major_importing() }
 			fn peers(&self) -> (usize, usize) {
 				let peers = ethsync::LightSyncProvider::peer_numbers(&*self.0);
@ -299,19 +307,26 @@ fn execute_light(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) ->
 			}
 		}

-		dapps::Dependencies {
-			sync_status: Arc::new(LightSyncStatus(light_sync.clone())),
-			pool: fetch.pool(),
+		let sync_status = Arc::new(LightSyncStatus(light_sync.clone()));
+		let node_health = node_health::NodeHealth::new(
+			sync_status.clone(),
+			node_health::TimeChecker::new(&cmd.ntp_servers, fetch.pool()),
+			event_loop.remote(),
+		);
+
+		(node_health.clone(), dapps::Dependencies {
+			sync_status,
+			node_health,
 			contract_client: contract_client,
 			remote: event_loop.raw_remote(),
 			fetch: fetch.clone(),
 			signer: signer_service.clone(),
 			ui_address: cmd.ui_conf.address(),
-		}
+		})
 	};

 	let dapps_middleware = dapps::new(cmd.dapps_conf.clone(), dapps_deps.clone())?;
-	let ui_middleware = dapps::new_ui(cmd.ui_conf.enabled, &cmd.ui_conf.ntp_servers, dapps_deps)?;
+	let ui_middleware = dapps::new_ui(cmd.ui_conf.enabled, dapps_deps)?;

 	// start RPCs
 	let dapps_service = dapps::service(&dapps_middleware);
@ -320,6 +335,7 @@ fn execute_light(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) ->
 		client: service.client().clone(),
 		sync: light_sync.clone(),
 		net: light_sync.clone(),
+		health: node_health,
 		secret_store: account_provider,
 		logger: logger,
 		settings: Arc::new(cmd.net_settings),
@ -661,12 +677,17 @@ pub fn execute(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) -> R
 	let signer_service = Arc::new(signer::new_service(&cmd.ws_conf, &cmd.ui_conf, &cmd.logger_config));

 	// the dapps server
-	let dapps_deps = {
+	let (node_health, dapps_deps) = {
 		let (sync, client) = (sync_provider.clone(), client.clone());
 		let contract_client = Arc::new(::dapps::FullRegistrar { client: client.clone() });

 		struct SyncStatus(Arc<ethsync::SyncProvider>, Arc<Client>, ethsync::NetworkConfiguration);
-		impl dapps::SyncStatus for SyncStatus {
+		impl fmt::Debug for SyncStatus {
+			fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+				write!(fmt, "Dapps Sync Status")
+			}
+		}
+		impl node_health::SyncStatus for SyncStatus {
 			fn is_major_importing(&self) -> bool {
 				is_major_importing(Some(self.0.status().state), self.1.queue_info())
 			}
@ -676,18 +697,24 @@ pub fn execute(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) -> R
 			}
 		}

-		dapps::Dependencies {
-			sync_status: Arc::new(SyncStatus(sync, client, net_conf)),
-			pool: fetch.pool(),
+		let sync_status = Arc::new(SyncStatus(sync, client, net_conf));
+		let node_health = node_health::NodeHealth::new(
+			sync_status.clone(),
+			node_health::TimeChecker::new(&cmd.ntp_servers, fetch.pool()),
+			event_loop.remote(),
+		);
+		(node_health.clone(), dapps::Dependencies {
+			sync_status,
+			node_health,
 			contract_client: contract_client,
 			remote: event_loop.raw_remote(),
 			fetch: fetch.clone(),
 			signer: signer_service.clone(),
 			ui_address: cmd.ui_conf.address(),
-		}
+		})
 	};
 	let dapps_middleware = dapps::new(cmd.dapps_conf.clone(), dapps_deps.clone())?;
-	let ui_middleware = dapps::new_ui(cmd.ui_conf.enabled, &cmd.ui_conf.ntp_servers, dapps_deps)?;
+	let ui_middleware = dapps::new_ui(cmd.ui_conf.enabled, dapps_deps)?;

 	let dapps_service = dapps::service(&dapps_middleware);
 	let deps_for_rpc_apis = Arc::new(rpc_apis::FullDependencies {
@ -695,6 +722,7 @@ pub fn execute(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) -> R
 		snapshot: snapshot_service.clone(),
 		client: client.clone(),
 		sync: sync_provider.clone(),
+		health: node_health,
 		net: manage_network.clone(),
 		secret_store: secret_store,
 		miner: miner.clone(),
--- a/rpc/Cargo.toml
+++ b/rpc/Cargo.toml
@ -47,12 +47,13 @@ ethjson = { path = "../json" }
 ethcore-devtools = { path = "../devtools" }
 ethcore-light = { path = "../ethcore/light" }
 ethcore-logger = { path = "../logger" }
-vm = { path = "../ethcore/vm" }
-parity-updater = { path = "../updater" }
-parity-reactor = { path = "../util/reactor" }
-rlp = { path = "../util/rlp" }
 fetch = { path = "../util/fetch" }
+node-health = { path = "../dapps/node-health" }
+parity-reactor = { path = "../util/reactor" }
+parity-updater = { path = "../updater" }
+rlp = { path = "../util/rlp" }
 stats = { path = "../util/stats" }
+vm = { path = "../ethcore/vm" }

 clippy = { version = "0.0.103", optional = true}
 pretty_assertions = "0.1"
--- a/rpc/src/lib.rs
+++ b/rpc/src/lib.rs
@ -55,6 +55,7 @@ extern crate ethsync;
 extern crate ethcore_logger;
 extern crate vm;
 extern crate fetch;
+extern crate node_health;
 extern crate parity_reactor;
 extern crate parity_updater as updater;
 extern crate rlp;
--- a/rpc/src/v1/helpers/dispatch.rs
+++ b/rpc/src/v1/helpers/dispatch.rs
@ -584,8 +584,9 @@ fn decrypt(accounts: &AccountProvider, address: Address, msg: Bytes, password: S
 }

 /// Extract the default gas price from a client and miner.
-pub fn default_gas_price<C, M>(client: &C, miner: &M) -> U256
-	where C: MiningBlockChainClient, M: MinerService
+pub fn default_gas_price<C, M>(client: &C, miner: &M) -> U256 where
+	C: MiningBlockChainClient,
+	M: MinerService,
 {
 	client.gas_price_corpus(100).median().cloned().unwrap_or_else(|| miner.sensible_gas_price())
 }
--- a/rpc/src/v1/helpers/fake_sign.rs
+++ b/rpc/src/v1/helpers/fake_sign.rs
@ -24,8 +24,8 @@ use jsonrpc_core::Error;
 use v1::helpers::CallRequest;
 use v1::helpers::dispatch::default_gas_price;

-pub fn sign_call<B: MiningBlockChainClient, M: MinerService>(
-	client: &Arc<B>,
+pub fn sign_call<C: MiningBlockChainClient, M: MinerService> (
+	client: &Arc<C>,
 	miner: &Arc<M>,
 	request: CallRequest,
 	gas_cap: bool,
--- a/rpc/src/v1/impls/light/parity.rs
+++ b/rpc/src/v1/impls/light/parity.rs
@ -19,15 +19,15 @@ use std::sync::Arc;
 use std::collections::{BTreeMap, HashSet};
 use futures::{future, Future, BoxFuture};

-use ethcore_logger::RotatingLogger;
 use util::misc::version_data;

-use crypto::ecies;
+use crypto::{ecies, DEFAULT_MAC};
 use ethkey::{Brain, Generator};
 use ethstore::random_phrase;
 use ethsync::LightSyncProvider;
 use ethcore::account_provider::AccountProvider;
-use crypto::DEFAULT_MAC;
+use ethcore_logger::RotatingLogger;
+use node_health::{NodeHealth, Health};

 use light::client::LightChainClient;

@ -53,6 +53,7 @@ pub struct ParityClient {
 	accounts: Arc<AccountProvider>,
 	logger: Arc<RotatingLogger>,
 	settings: Arc<NetworkSettings>,
+	health: NodeHealth,
 	signer: Option<Arc<SignerService>>,
 	dapps_address: Option<(String, u16)>,
 	ws_address: Option<(String, u16)>,
@ -67,18 +68,20 @@ impl ParityClient {
 		accounts: Arc<AccountProvider>,
 		logger: Arc<RotatingLogger>,
 		settings: Arc<NetworkSettings>,
+		health: NodeHealth,
 		signer: Option<Arc<SignerService>>,
 		dapps_address: Option<(String, u16)>,
 		ws_address: Option<(String, u16)>,
 	) -> Self {
 		ParityClient {
-			light_dispatch: light_dispatch,
-			accounts: accounts,
-			logger: logger,
-			settings: settings,
-			signer: signer,
-			dapps_address: dapps_address,
-			ws_address: ws_address,
+			light_dispatch,
+			accounts,
+			logger,
+			settings,
+			health,
+			signer,
+			dapps_address,
+			ws_address,
 			eip86_transition: client.eip86_transition(),
 		}
 	}
@ -393,4 +396,10 @@ impl Parity for ParityClient {
 	fn call(&self, _meta: Self::Metadata, _requests: Vec<CallRequest>, _block: Trailing<BlockNumber>) -> BoxFuture<Vec<Bytes>, Error> {
 		future::err(errors::light_unimplemented(None)).boxed()
 	}
+
+	fn node_health(&self) -> BoxFuture<Health, Error> {
+		self.health.health()
+			.map_err(|err| errors::internal("Health API failure.", err))
+			.boxed()
+	}
 }
--- a/rpc/src/v1/impls/parity.rs
+++ b/rpc/src/v1/impls/parity.rs
@ -20,11 +20,10 @@ use std::str::FromStr;
 use std::collections::{BTreeMap, HashSet};
 use futures::{future, Future, BoxFuture};

-use ethcore_logger::RotatingLogger;
 use util::Address;
 use util::misc::version_data;

-use crypto::ecies;
+use crypto::{DEFAULT_MAC, ecies};
 use ethkey::{Brain, Generator};
 use ethstore::random_phrase;
 use ethsync::{SyncProvider, ManageNetwork};
@ -34,8 +33,9 @@ use ethcore::ids::BlockId;
 use ethcore::miner::MinerService;
 use ethcore::mode::Mode;
 use ethcore::transaction::SignedTransaction;
+use ethcore_logger::RotatingLogger;
+use node_health::{NodeHealth, Health};
 use updater::{Service as UpdateService};
-use crypto::DEFAULT_MAC;

 use jsonrpc_core::Error;
 use jsonrpc_macros::Trailing;
@ -53,17 +53,13 @@ use v1::types::{
 };

 /// Parity implementation.
-pub struct ParityClient<C, M, S: ?Sized, U> where
-	C: MiningBlockChainClient,
-	M: MinerService,
-	S: SyncProvider,
-	U: UpdateService,
-{
+pub struct ParityClient<C, M, U>  {
 	client: Arc<C>,
 	miner: Arc<M>,
-	sync: Arc<S>,
 	updater: Arc<U>,
+	sync: Arc<SyncProvider>,
 	net: Arc<ManageNetwork>,
+	health: NodeHealth,
 	accounts: Option<Arc<AccountProvider>>,
 	logger: Arc<RotatingLogger>,
 	settings: Arc<NetworkSettings>,
@ -73,39 +69,39 @@ pub struct ParityClient<C, M, S: ?Sized, U> where
 	eip86_transition: u64,
 }

-impl<C, M, S: ?Sized, U> ParityClient<C, M, S, U> where
+impl<C, M, U> ParityClient<C, M, U> where
 	C: MiningBlockChainClient,
-	M: MinerService,
-	S: SyncProvider,
-	U: UpdateService,
 {
 	/// Creates new `ParityClient`.
 	pub fn new(
-		client: &Arc<C>,
-		miner: &Arc<M>,
-		sync: &Arc<S>,
-		updater: &Arc<U>,
-		net: &Arc<ManageNetwork>,
-		store: &Option<Arc<AccountProvider>>,
+		client: Arc<C>,
+		miner: Arc<M>,
+		sync: Arc<SyncProvider>,
+		updater: Arc<U>,
+		net: Arc<ManageNetwork>,
+		health: NodeHealth,
+		accounts: Option<Arc<AccountProvider>>,
 		logger: Arc<RotatingLogger>,
 		settings: Arc<NetworkSettings>,
 		signer: Option<Arc<SignerService>>,
 		dapps_address: Option<(String, u16)>,
 		ws_address: Option<(String, u16)>,
 	) -> Self {
+		let eip86_transition = client.eip86_transition();
 		ParityClient {
-			client: client.clone(),
-			miner: miner.clone(),
-			sync: sync.clone(),
-			updater: updater.clone(),
-			net: net.clone(),
-			accounts: store.clone(),
-			logger: logger,
-			settings: settings,
-			signer: signer,
-			dapps_address: dapps_address,
-			ws_address: ws_address,
-			eip86_transition: client.eip86_transition(),
+			client,
+			miner,
+			sync,
+			updater,
+			net,
+			health,
+			accounts,
+			logger,
+			settings,
+			signer,
+			dapps_address,
+			ws_address,
+			eip86_transition,
 		}
 	}

@ -116,10 +112,9 @@ impl<C, M, S: ?Sized, U> ParityClient<C, M, S, U> where
 	}
 }

-impl<C, M, S: ?Sized, U> Parity for ParityClient<C, M, S, U> where
-	M: MinerService + 'static,
+impl<C, M, U> Parity for ParityClient<C, M, U> where
 	C: MiningBlockChainClient + 'static,
-	S: SyncProvider + 'static,
+	M: MinerService + 'static,
 	U: UpdateService + 'static,
 {
 	type Metadata = Metadata;
@ -429,4 +424,10 @@ impl<C, M, S: ?Sized, U> Parity for ParityClient<C, M, S, U> where

 		future::done(result).boxed()
 	}
+
+	fn node_health(&self) -> BoxFuture<Health, Error> {
+		self.health.health()
+			.map_err(|err| errors::internal("Health API failure.", err))
+			.boxed()
+	}
 }
--- a/rpc/src/v1/tests/mocked/parity.rs
+++ b/rpc/src/v1/tests/mocked/parity.rs
@ -15,13 +15,15 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

 use std::sync::Arc;
-use ethcore_logger::RotatingLogger;
-use util::{Address, U256};
-use ethsync::ManageNetwork;
 use ethcore::account_provider::AccountProvider;
 use ethcore::client::{TestBlockChainClient, Executed};
 use ethcore::miner::LocalTransactionStatus;
+use ethcore_logger::RotatingLogger;
 use ethstore::ethkey::{Generator, Random};
+use ethsync::ManageNetwork;
+use node_health::{self, NodeHealth};
+use parity_reactor;
+use util::Address;

 use jsonrpc_core::IoHandler;
 use v1::{Parity, ParityClient};
@ -30,13 +32,14 @@ use v1::helpers::{SignerService, NetworkSettings};
 use v1::tests::helpers::{TestSyncProvider, Config, TestMinerService, TestUpdater};
 use super::manage_network::TestManageNetwork;

-pub type TestParityClient = ParityClient<TestBlockChainClient, TestMinerService, TestSyncProvider, TestUpdater>;
+pub type TestParityClient = ParityClient<TestBlockChainClient, TestMinerService, TestUpdater>;

 pub struct Dependencies {
 	pub miner: Arc<TestMinerService>,
 	pub client: Arc<TestBlockChainClient>,
 	pub sync: Arc<TestSyncProvider>,
 	pub updater: Arc<TestUpdater>,
+	pub health: NodeHealth,
 	pub logger: Arc<RotatingLogger>,
 	pub settings: Arc<NetworkSettings>,
 	pub network: Arc<ManageNetwork>,
@ -54,6 +57,11 @@ impl Dependencies {
 				network_id: 3,
 				num_peers: 120,
 			})),
+			health: NodeHealth::new(
+				Arc::new(FakeSync),
+				node_health::TimeChecker::new::<String>(&[], node_health::CpuPool::new(1)),
+				parity_reactor::Remote::new_sync(),
+			),
 			updater: Arc::new(TestUpdater::default()),
 			logger: Arc::new(RotatingLogger::new("rpc=trace".to_owned())),
 			settings: Arc::new(NetworkSettings {
@ -75,12 +83,13 @@ impl Dependencies {
 		let opt_accounts = Some(self.accounts.clone());

 		ParityClient::new(
-			&self.client,
-			&self.miner,
-			&self.sync,
-			&self.updater,
-			&self.network,
-			&opt_accounts,
+			self.client.clone(),
+			self.miner.clone(),
+			self.sync.clone(),
+			self.updater.clone(),
+			self.network.clone(),
+			self.health.clone(),
+			opt_accounts.clone(),
 			self.logger.clone(),
 			self.settings.clone(),
 			signer,
@ -102,6 +111,13 @@ impl Dependencies {
 	}
 }

+#[derive(Debug)]
+struct FakeSync;
+impl node_health::SyncStatus for FakeSync {
+	fn is_major_importing(&self) -> bool { false }
+	fn peers(&self) -> (usize, usize) { (4, 25) }
+}
+
 #[test]
 fn rpc_parity_accounts_info() {
 	let deps = Dependencies::new();
@ -507,6 +523,8 @@ fn rpc_parity_cid() {

 #[test]
 fn rpc_parity_call() {
+	use util::U256;
+
 	let deps = Dependencies::new();
 	deps.client.set_execution_result(Ok(Executed {
 		exception: None,
@ -541,3 +559,14 @@ fn rpc_parity_call() {

 	assert_eq!(io.handle_request_sync(request), Some(response.to_owned()));
 }
+
+#[test]
+fn rpc_parity_node_health() {
+	let deps = Dependencies::new();
+	let io = deps.default_client();
+
+	let request = r#"{"jsonrpc": "2.0", "method": "parity_nodeHealth", "params":[], "id": 1}"#;
+	let response = r#"{"jsonrpc":"2.0","result":{"peers":{"details":[4,25],"message":"","status":"ok"},"sync":{"details":false,"message":"","status":"ok"},"time":{"details":0,"message":"","status":"ok"}},"id":1}"#;
+
+	assert_eq!(io.handle_request_sync(request), Some(response.to_owned()));
+}
--- a/rpc/src/v1/traits/parity.rs
+++ b/rpc/src/v1/traits/parity.rs
@ -22,6 +22,7 @@ use jsonrpc_core::Error;
 use jsonrpc_macros::Trailing;
 use futures::BoxFuture;

+use node_health::Health;
 use v1::types::{
 	H160, H256, H512, U256, Bytes, CallRequest,
 	Peers, Transaction, RpcSettings, Histogram,
@ -207,5 +208,9 @@ build_rpc_trait! {
 		/// Call contract, returning the output data.
 		#[rpc(meta, name = "parity_call")]
 		fn call(&self, Self::Metadata, Vec<CallRequest>, Trailing<BlockNumber>) -> BoxFuture<Vec<Bytes>, Error>;
+
+		/// Returns node's health report.
+		#[rpc(async, name = "parity_nodeHealth")]
+		fn node_health(&self) -> BoxFuture<Health, Error>;
 	}
 }
--- a/test.sh
+++ b/test.sh
@ -26,4 +26,4 @@ set -e

 ./scripts/validate_chainspecs.sh

-cargo test -j 8 $OPTIONS --features "$FEATURES" --all --exclude parity-ipfs-api --exclude evmjit $1
+cargo test -j 8 $OPTIONS --features "$FEATURES" --all --exclude evmjit $1
--- a/util/bigint/Cargo.toml
+++ b/util/bigint/Cargo.toml
@ -13,6 +13,7 @@ rustc-hex = "1.0"
 rand = "0.3.12"
 libc = "0.2"
 heapsize = { version = "0.4", optional = true }
+plain_hasher = { path = "../plain_hasher" }

 [features]
 x64asm_arithmetic=[]
--- a/util/bigint/src/hash.rs
+++ b/util/bigint/src/hash.rs
@ -16,6 +16,7 @@ use std::collections::{HashMap, HashSet};
 use rand::{Rand, Rng};
 use rand::os::OsRng;
 use rustc_hex::{FromHex, FromHexError};
+use plain_hasher::PlainHasher;
 use bigint::U256;
 use libc::{c_void, memcmp};

@ -446,41 +447,6 @@ impl_hash!(H2048, 256);
 known_heap_size!(0, H32, H64, H128, H160, H256, H264, H512, H520, H1024, H2048);
 // Specialized HashMap and HashSet

-/// Hasher that just takes 8 bytes of the provided value.
-/// May only be used for keys which are 32 bytes.
-pub struct PlainHasher {
-	prefix: [u8; 8],
-	_marker: [u64; 0], // for alignment
-}
-
-impl Default for PlainHasher {
-	#[inline]
-	fn default() -> PlainHasher {
-		PlainHasher {
-			prefix: [0; 8],
-			_marker: [0; 0],
-		}
-	}
-}
-
-impl Hasher for PlainHasher {
-	#[inline]
-	fn finish(&self) -> u64 {
-		unsafe { ::std::mem::transmute(self.prefix) }
-	}
-
-	#[inline]
-	fn write(&mut self, bytes: &[u8]) {
-		debug_assert!(bytes.len() == 32);
-
-		for quarter in bytes.chunks(8) {
-			for (x, y) in self.prefix.iter_mut().zip(quarter) {
-				*x ^= *y
-			}
-		}
-	}
-}
-
 /// Specialized version of `HashMap` with H256 keys and fast hashing function.
 pub type H256FastMap<T> = HashMap<H256, T, BuildHasherDefault<PlainHasher>>;
 /// Specialized version of `HashSet` with H256 keys and fast hashing function.
--- a/util/bigint/src/lib.rs
+++ b/util/bigint/src/lib.rs
@ -14,6 +14,7 @@ extern crate rand;
 extern crate rustc_hex;
 extern crate bigint;
 extern crate libc;
+extern crate plain_hasher;

 #[cfg(feature="heapsizeof")]
 #[macro_use]
--- a/util/bloom/src/lib.rs
+++ b/util/bloom/src/lib.rs
@ -37,9 +37,9 @@ struct BitVecJournal {

 impl BitVecJournal {
 	pub fn new(size: usize) -> BitVecJournal {
-		let extra = if size % 8 > 0  { 1 } else { 0 };
+		let extra = if size % 64 > 0  { 1 } else { 0 };
 		BitVecJournal {
-			elems: vec![0u64; size / 8 + extra],
+			elems: vec![0u64; size / 64 + extra],
 			journal: HashSet::new(),
 		}
 	}
--- a/util/plain_hasher/Cargo.toml
+++ b/util/plain_hasher/Cargo.toml
@ -0,0 +1,12 @@
+[package]
+name = "plain_hasher"
+description = "Hasher for 32-bit keys."
+version = "0.1.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+license = "MIT"
+keywords = ["hash", "hasher"]
+categories = ["no-std"]
+homepage = "https://github.com/paritytech/plain_hasher"
+
+[dependencies]
+crunchy = "0.1.6"
--- a/util/plain_hasher/benches/bench.rs
+++ b/util/plain_hasher/benches/bench.rs
@ -0,0 +1,33 @@
+#![feature(test)]
+
+extern crate test;
+extern crate plain_hasher;
+
+use std::hash::Hasher;
+use std::collections::hash_map::DefaultHasher;
+use test::{Bencher, black_box};
+use plain_hasher::PlainHasher;
+
+#[bench]
+fn write_plain_hasher(b: &mut Bencher) {
+	b.iter(|| {
+		let n: u8 = black_box(100);
+		(0..n).fold(PlainHasher::default(), |mut old, new| {
+			let bb = black_box([new; 32]);
+			old.write(&bb as &[u8]);
+			old
+		});
+	});
+}
+
+#[bench]
+fn write_default_hasher(b: &mut Bencher) {
+	b.iter(|| {
+		let n: u8 = black_box(100);
+		(0..n).fold(DefaultHasher::default(), |mut old, new| {
+			let bb = black_box([new; 32]);
+			old.write(&bb as &[u8]);
+			old
+		});
+	});
+}
--- a/util/plain_hasher/src/lib.rs
+++ b/util/plain_hasher/src/lib.rs
@ -0,0 +1,55 @@
+#![no_std]
+#[macro_use]
+extern crate crunchy;
+
+use core::{hash, mem};
+
+/// Hasher that just takes 8 bytes of the provided value.
+/// May only be used for keys which are 32 bytes.
+#[derive(Default)]
+pub struct PlainHasher {
+	prefix: u64,
+}
+
+impl hash::Hasher for PlainHasher {
+	#[inline]
+	fn finish(&self) -> u64 {
+		self.prefix
+	}
+
+	#[inline]
+	#[allow(unused_assignments)]
+	fn write(&mut self, bytes: &[u8]) {
+		debug_assert!(bytes.len() == 32);
+
+		unsafe {
+			let mut bytes_ptr = bytes.as_ptr();
+			let prefix_u8: &mut [u8; 8] = mem::transmute(&mut self.prefix);
+			let mut prefix_ptr = prefix_u8.as_mut_ptr();
+
+			unroll! {
+				for _i in 0..8 {
+					*prefix_ptr ^= (*bytes_ptr ^ *bytes_ptr.offset(8)) ^ (*bytes_ptr.offset(16) ^ *bytes_ptr.offset(24));
+
+					bytes_ptr = bytes_ptr.offset(1);
+					prefix_ptr = prefix_ptr.offset(1);
+				}
+			}
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use core::hash::Hasher;
+	use super::PlainHasher;
+
+	#[test]
+	fn it_works() {
+		let mut bytes = [32u8; 32];
+		bytes[0] = 15;
+		let mut hasher = PlainHasher::default();
+		hasher.write(&bytes);
+		assert_eq!(hasher.prefix, 47);
+	}
+}
--- a/util/reactor/src/lib.rs
+++ b/util/reactor/src/lib.rs
@ -20,7 +20,7 @@
 extern crate futures;
 extern crate tokio_core;

-use std::thread;
+use std::{fmt, thread};
 use std::sync::mpsc;
 use std::time::Duration;
 use futures::{Future, IntoFuture};
@ -81,7 +81,19 @@ enum Mode {
 	ThreadPerFuture,
 }

-#[derive(Clone)]
+impl fmt::Debug for Mode {
+	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+		use self::Mode::*;
+
+		match *self {
+			Tokio(_) => write!(fmt, "tokio"),
+			Sync => write!(fmt, "synchronous"),
+			ThreadPerFuture => write!(fmt, "thread per future"),
+		}
+	}
+}
+
+#[derive(Debug, Clone)]
 pub struct Remote {
 	inner: Mode,
 }
--- a/util/src/journaldb/archivedb.rs
+++ b/util/src/journaldb/archivedb.rs
@ -17,6 +17,7 @@
 //! Disk-backed `HashDB` implementation.

 use std::collections::HashMap;
+use std::collections::hash_map::Entry;
 use std::sync::Arc;
 use rlp::*;
 use hashdb::*;
@ -66,23 +67,28 @@ impl ArchiveDB {

 impl HashDB for ArchiveDB {
 	fn keys(&self) -> HashMap<H256, i32> {
-		let mut ret: HashMap<H256, i32> = HashMap::new();
-		for (key, _) in self.backing.iter(self.column) {
-			let h = H256::from_slice(&*key);
-			ret.insert(h, 1);
-		}
+		let mut ret: HashMap<H256, i32> = self.backing.iter(self.column)
+			.map(|(key, _)| (H256::from_slice(&*key), 1))
+			.collect();

 		for (key, refs) in self.overlay.keys() {
-			let refs = *ret.get(&key).unwrap_or(&0) + refs;
-			ret.insert(key, refs);
+			match ret.entry(key) {
+				Entry::Occupied(mut entry) => {
+					*entry.get_mut() += refs;
+				},
+				Entry::Vacant(entry) => {
+					entry.insert(refs);
+				}
+			}
 		}
 		ret
 	}

 	fn get(&self, key: &H256) -> Option<DBValue> {
-		let k = self.overlay.raw(key);
-		if let Some((d, rc)) = k {
-			if rc > 0 { return Some(d); }
+		if let Some((d, rc)) = self.overlay.raw(key) {
+			if rc > 0 {
+				return Some(d);
+			}
 		}
 		self.payload(key)
 	}
--- a/util/src/journaldb/earlymergedb.rs
+++ b/util/src/journaldb/earlymergedb.rs
@ -18,6 +18,7 @@

 use std::fmt;
 use std::collections::HashMap;
+use std::collections::hash_map::Entry;
 use std::sync::Arc;
 use parking_lot::RwLock;
 use heapsize::HeapSizeOf;
@ -159,49 +160,59 @@ impl EarlyMergeDB {

 	fn insert_keys(inserts: &[(H256, DBValue)], backing: &KeyValueDB, col: Option<u32>, refs: &mut HashMap<H256, RefInfo>, batch: &mut DBTransaction, trace: bool) {
 		for &(ref h, ref d) in inserts {
-			if let Some(c) = refs.get_mut(h) {
+			match refs.entry(*h) {
+				Entry::Occupied(mut entry) => {
+					let info = entry.get_mut();
 					// already counting. increment.
-				c.queue_refs += 1;
+					info.queue_refs += 1;
 					if trace {
-					trace!(target: "jdb.fine", "    insert({}): In queue: Incrementing refs to {}", h, c.queue_refs);
+						trace!(target: "jdb.fine", "    insert({}): In queue: Incrementing refs to {}", h, info.queue_refs);
 					}
-				continue;
-			}
-
+				},
+				Entry::Vacant(entry) => {
 					// this is the first entry for this node in the journal.
-			if backing.get(col, h).expect("Low-level database error. Some issue with your hard disk?").is_some() {
+					let in_archive = backing.get(col, h).expect("Low-level database error. Some issue with your hard disk?").is_some();
+					if in_archive {
 						// already in the backing DB. start counting, and remember it was already in.
 						Self::set_already_in(batch, col, h);
-				refs.insert(h.clone(), RefInfo{queue_refs: 1, in_archive: true});
 						if trace {
 							trace!(target: "jdb.fine", "    insert({}): New to queue, in DB: Recording and inserting into queue", h);
 						}
-				continue;
-			}
-
+					} else {
 						// Gets removed when a key leaves the journal, so should never be set when we're placing a new key.
 						//Self::reset_already_in(&h);
-			assert!(!Self::is_already_in(backing, col, &h));
-			batch.put(col, h, d);
-			refs.insert(h.clone(), RefInfo{queue_refs: 1, in_archive: false});
+						assert!(!Self::is_already_in(backing, col, h));
 						if trace {
 							trace!(target: "jdb.fine", "    insert({}): New to queue, not in DB: Inserting into queue and DB", h);
 						}
+						batch.put(col, h, d);
+					}
+					entry.insert(RefInfo {
+						queue_refs: 1,
+						in_archive: in_archive,
+					});
+				},
+			}
 		}
 	}

 	fn replay_keys(inserts: &[H256], backing: &KeyValueDB, col: Option<u32>, refs: &mut HashMap<H256, RefInfo>) {
 		trace!(target: "jdb.fine", "replay_keys: inserts={:?}, refs={:?}", inserts, refs);
 		for h in inserts {
-			if let Some(c) = refs.get_mut(h) {
+			match refs.entry(*h) {
 				// already counting. increment.
-				c.queue_refs += 1;
-				continue;
-			}
-
+				Entry::Occupied(mut entry) => {
+					entry.get_mut().queue_refs += 1;
+				},
 				// this is the first entry for this node in the journal.
 				// it is initialised to 1 if it was already in.
-			refs.insert(h.clone(), RefInfo{queue_refs: 1, in_archive: Self::is_already_in(backing, col, h)});
+				Entry::Vacant(entry) => {
+					entry.insert(RefInfo {
+						queue_refs: 1,
+						in_archive: Self::is_already_in(backing, col, h),
+					});
+				},
+			}
 		}
 		trace!(target: "jdb.fine", "replay_keys: (end) refs={:?}", refs);
 	}
@ -213,50 +224,54 @@ impl EarlyMergeDB {
 		// (the latter option would then mean removing the RefInfo, since it would no longer be counted in the queue.)
 		// both are valid, but we switch between them depending on context.
 		//     All inserts in queue (i.e. those which may yet be reverted) have an entry in refs.
-		for h in deletes.iter() {
-			let mut n: Option<RefInfo> = None;
-			if let Some(c) = refs.get_mut(h) {
-				if c.in_archive && from == RemoveFrom::Archive {
-					c.in_archive = false;
+		for h in deletes {
+			match refs.entry(*h) {
+				Entry::Occupied(mut entry) => {
+					if entry.get().in_archive && from == RemoveFrom::Archive {
+						entry.get_mut().in_archive = false;
 						Self::reset_already_in(batch, col, h);
 						if trace {
 							trace!(target: "jdb.fine", "    remove({}): In archive, 1 in queue: Reducing to queue only and recording", h);
 						}
 						continue;
-				} else if c.queue_refs > 1 {
-					c.queue_refs -= 1;
+					}
+					if entry.get().queue_refs > 1 {
+						entry.get_mut().queue_refs -= 1;
 						if trace {
-						trace!(target: "jdb.fine", "    remove({}): In queue > 1 refs: Decrementing ref count to {}", h, c.queue_refs);
+							trace!(target: "jdb.fine", "    remove({}): In queue > 1 refs: Decrementing ref count to {}", h, entry.get().queue_refs);
 						}
 						continue;
-				} else {
-					n = Some(c.clone());
 					}
-			}
-			match n {
-				Some(RefInfo{queue_refs: 1, in_archive: true}) => {
-					refs.remove(h);
+
+					let queue_refs = entry.get().queue_refs;
+					let in_archive = entry.get().in_archive;
+
+					match (queue_refs, in_archive) {
+						(1, true) => {
+							entry.remove();
 							Self::reset_already_in(batch, col, h);
 							if trace {
 								trace!(target: "jdb.fine", "    remove({}): In archive, 1 in queue: Removing from queue and leaving in archive", h);
 							}
-				}
-				Some(RefInfo{queue_refs: 1, in_archive: false}) => {
-					refs.remove(h);
+						},
+						(1, false) => {
+							entry.remove();
 							batch.delete(col, h);
 							if trace {
 								trace!(target: "jdb.fine", "    remove({}): Not in archive, only 1 ref in queue: Removing from queue and DB", h);
 							}
+						},
+						_ => panic!("Invalid value in refs: {:?}", entry.get()),
 					}
-				None => {
+				},
+				Entry::Vacant(_entry) => {
 					// Gets removed when moving from 1 to 0 additional refs. Should never be here at 0 additional refs.
 					//assert!(!Self::is_already_in(db, &h));
 					batch.delete(col, h);
 					if trace {
 						trace!(target: "jdb.fine", "    remove({}): Not in queue - MUST BE IN ARCHIVE: Removing from DB", h);
 					}
-				}
-				_ => panic!("Invalid value in refs: {:?}", n),
+				},
 			}
 		}
 	}
@ -311,23 +326,28 @@ impl EarlyMergeDB {

 impl HashDB for EarlyMergeDB {
 	fn keys(&self) -> HashMap<H256, i32> {
-		let mut ret: HashMap<H256, i32> = HashMap::new();
-		for (key, _) in self.backing.iter(self.column) {
-			let h = H256::from_slice(&*key);
-			ret.insert(h, 1);
-		}
+		let mut ret: HashMap<H256, i32> = self.backing.iter(self.column)
+			.map(|(key, _)| (H256::from_slice(&*key), 1))
+			.collect();

 		for (key, refs) in self.overlay.keys() {
-			let refs = *ret.get(&key).unwrap_or(&0) + refs;
-			ret.insert(key, refs);
+			match ret.entry(key) {
+				Entry::Occupied(mut entry) => {
+					*entry.get_mut() += refs;
+				},
+				Entry::Vacant(entry) => {
+					entry.insert(refs);
+				}
+			}
 		}
 		ret
 	}

 	fn get(&self, key: &H256) -> Option<DBValue> {
-		let k = self.overlay.raw(key);
-		if let Some((d, rc)) = k {
-			if rc > 0 { return Some(d) }
+		if let Some((d, rc)) = self.overlay.raw(key) {
+			if rc > 0 {
+				return Some(d)
+			}
 		}
 		self.payload(key)
 	}
--- a/util/src/journaldb/overlayrecentdb.rs
+++ b/util/src/journaldb/overlayrecentdb.rs
@ -17,6 +17,7 @@
 //! `JournalDB` over in-memory overlay

 use std::collections::HashMap;
+use std::collections::hash_map::Entry;
 use std::sync::Arc;
 use parking_lot::RwLock;
 use heapsize::HeapSizeOf;
@ -407,23 +408,28 @@ impl JournalDB for OverlayRecentDB {

 impl HashDB for OverlayRecentDB {
 	fn keys(&self) -> HashMap<H256, i32> {
-		let mut ret: HashMap<H256, i32> = HashMap::new();
-		for (key, _) in self.backing.iter(self.column) {
-			let h = H256::from_slice(&*key);
-			ret.insert(h, 1);
-		}
+		let mut ret: HashMap<H256, i32> = self.backing.iter(self.column)
+			.map(|(key, _)| (H256::from_slice(&*key), 1))
+			.collect();

 		for (key, refs) in self.transaction_overlay.keys() {
-			let refs = *ret.get(&key).unwrap_or(&0) + refs;
-			ret.insert(key, refs);
+			match ret.entry(key) {
+				Entry::Occupied(mut entry) => {
+					*entry.get_mut() += refs;
+				},
+				Entry::Vacant(entry) => {
+					entry.insert(refs);
+				}
+			}
 		}
 		ret
 	}

 	fn get(&self, key: &H256) -> Option<DBValue> {
-		let k = self.transaction_overlay.raw(key);
-		if let Some((d, rc)) = k {
-			if rc > 0 { return Some(d) }
+		if let Some((d, rc)) = self.transaction_overlay.raw(key) {
+			if rc > 0 {
+				return Some(d)
+			}
 		}
 		let v = {
 			let journal_overlay = self.journal_overlay.read();
--- a/util/src/journaldb/refcounteddb.rs
+++ b/util/src/journaldb/refcounteddb.rs
@ -198,7 +198,7 @@ impl JournalDB for RefCountedDB {
 	fn consolidate(&mut self, mut with: MemoryDB) {
 		for (key, (value, rc)) in with.drain() {
 			for _ in 0..rc {
-				self.emplace(key.clone(), value.clone());
+				self.emplace(key, value.clone());
 			}

 			for _ in rc..0 {
--- a/util/src/memorydb.rs
+++ b/util/src/memorydb.rs
@ -16,14 +16,14 @@

 //! Reference-counted memory-based `HashDB` implementation.

-use hash::*;
-use rlp::*;
-use sha3::*;
-use hashdb::*;
-use heapsize::*;
 use std::mem;
 use std::collections::HashMap;
 use std::collections::hash_map::Entry;
+use heapsize::HeapSizeOf;
+use hash::{H256FastMap, H256};
+use rlp::NULL_RLP;
+use sha3::*;
+use hashdb::*;

 /// Reference-counted memory-based `HashDB` implementation.
 ///
@ -181,7 +181,13 @@ impl HashDB for MemoryDB {
 	}

 	fn keys(&self) -> HashMap<H256, i32> {
-		self.data.iter().filter_map(|(k, v)| if v.1 != 0 {Some((k.clone(), v.1))} else {None}).collect()
+		self.data.iter()
+			.filter_map(|(k, v)| if v.1 != 0 {
+				Some((*k, v.1))
+			} else {
+				None
+			})
+			.collect()
 	}

 	fn contains(&self, key: &H256) -> bool {
@ -200,16 +206,17 @@ impl HashDB for MemoryDB {
 			return SHA3_NULL_RLP.clone();
 		}
 		let key = value.sha3();
-		if match self.data.get_mut(&key) {
-			Some(&mut (ref mut old_value, ref mut rc @ -0x80000000i32 ... 0)) => {
+		match self.data.entry(key) {
+			Entry::Occupied(mut entry) => {
+				let &mut (ref mut old_value, ref mut rc) = entry.get_mut();
+				if *rc >= -0x80000000i32 && *rc <= 0 {
 					*old_value = DBValue::from_slice(value);
+				}
 				*rc += 1;
-				false
 			},
-			Some(&mut (_, ref mut x)) => { *x += 1; false } ,
-			None => true,
-		}{	// ... None falls through into...
-			self.data.insert(key.clone(), (DBValue::from_slice(value), 1));
+			Entry::Vacant(entry) => {
+				entry.insert((DBValue::from_slice(value), 1));
+			},
 		}
 		key
 	}
@ -219,17 +226,18 @@ impl HashDB for MemoryDB {
 			return;
 		}

-		match self.data.get_mut(&key) {
-			Some(&mut (ref mut old_value, ref mut rc @ -0x80000000i32 ... 0)) => {
+		match self.data.entry(key) {
+			Entry::Occupied(mut entry) => {
+				let &mut (ref mut old_value, ref mut rc) = entry.get_mut();
+				if *rc >= -0x80000000i32 && *rc <= 0 {
 					*old_value = value;
-				*rc += 1;
-				return;
-			},
-			Some(&mut (_, ref mut x)) => { *x += 1; return; } ,
-			None => {},
 				}
-		// ... None falls through into...
-		self.data.insert(key, (value, 1));
+				*rc += 1;
+			},
+			Entry::Vacant(entry) => {
+				entry.insert((value, 1));
+			},
+		}
 	}

 	fn remove(&mut self, key: &H256) {
@ -237,11 +245,14 @@ impl HashDB for MemoryDB {
 			return;
 		}

-		if match self.data.get_mut(key) {
-			Some(&mut (_, ref mut x)) => { *x -= 1; false }
-			None => true
-		}{	// ... None falls through into...
-			self.data.insert(key.clone(), (DBValue::new(), -1));
+		match self.data.entry(*key) {
+			Entry::Occupied(mut entry) => {
+				let &mut (_, ref mut rc) = entry.get_mut();
+				*rc -= 1;
+			},
+			Entry::Vacant(entry) => {
+				entry.insert((DBValue::new(), -1));
+			},
 		}
 	}
 }
--- a/util/src/overlaydb.rs
+++ b/util/src/overlaydb.rs
@ -16,13 +16,14 @@

 //! Disk-backed `HashDB` implementation.

+use std::sync::Arc;
+use std::collections::HashMap;
+use std::collections::hash_map::Entry;
 use error::*;
 use hash::*;
 use rlp::*;
 use hashdb::*;
 use memorydb::*;
-use std::sync::*;
-use std::collections::HashMap;
 use kvdb::{KeyValueDB, DBTransaction};

 /// Implementation of the `HashDB` trait for a disk-backed database with a memory overlay.
@ -125,19 +126,27 @@ impl OverlayDB {

 impl HashDB for OverlayDB {
 	fn keys(&self) -> HashMap<H256, i32> {
-		let mut ret: HashMap<H256, i32> = HashMap::new();
-		for (key, _) in self.backing.iter(self.column) {
+		let mut ret: HashMap<H256, i32> = self.backing.iter(self.column)
+			.map(|(key, _)| {
 				let h = H256::from_slice(&*key);
 				let r = self.payload(&h).unwrap().1;
-			ret.insert(h, r as i32);
-		}
+				(h, r as i32)
+			})
+			.collect();

 		for (key, refs) in self.overlay.keys() {
-			let refs = *ret.get(&key).unwrap_or(&0) + refs;
-			ret.insert(key, refs);
+			match ret.entry(key) {
+				Entry::Occupied(mut entry) => {
+					*entry.get_mut() += refs;
+				},
+				Entry::Vacant(entry) => {
+					entry.insert(refs);
+				}
+			}
 		}
 		ret
 	}
+
 	fn get(&self, key: &H256) -> Option<DBValue> {
 		// return ok if positive; if negative, check backing - might be enough references there to make
 		// it positive again.
@ -165,6 +174,7 @@ impl HashDB for OverlayDB {
 			_ => None,
 		}
 	}
+
 	fn contains(&self, key: &H256) -> bool {
 		// return ok if positive; if negative, check backing - might be enough references there to make
 		// it positive again.
@ -185,6 +195,7 @@ impl HashDB for OverlayDB {
 			}
 		}
 	}
+
 	fn insert(&mut self, value: &[u8]) -> H256 { self.overlay.insert(value) }
 	fn emplace(&mut self, key: H256, value: DBValue) { self.overlay.emplace(key, value); }
 	fn remove(&mut self, key: &H256) { self.overlay.remove(key); }
--- a/util/src/trie/triedb.rs
+++ b/util/src/trie/triedb.rs
@ -217,10 +217,12 @@ impl<'a> TrieDBIterator<'a> {
 		Ok(r)
 	}

-	fn seek_descend<'key>(&mut self, node_data: DBValue, key: &NibbleSlice<'key>) -> super::Result<()> {
+	fn seek<'key>(&mut self, mut node_data: DBValue, mut key: NibbleSlice<'key>) -> super::Result<()> {
+		loop {
+			let (data, mid) = {
 				let node = Node::decoded(&node_data);
 				match node {
-			Node::Leaf(ref slice, _) => {
+					Node::Leaf(slice, _) => {
 						if slice == key {
 							self.trail.push(Crumb {
 								status: Status::At,
@ -234,7 +236,7 @@ impl<'a> TrieDBIterator<'a> {
 						}

 						self.key_nibbles.extend(slice.iter());
-				Ok(())
+						return Ok(())
 					},
 					Node::Extension(ref slice, ref item) => {
 						if key.starts_with(slice) {
@ -244,10 +246,10 @@ impl<'a> TrieDBIterator<'a> {
 							});
 							self.key_nibbles.extend(slice.iter());
 							let data = self.db.get_raw_or_lookup(&*item)?;
-					self.seek_descend(data, &key.mid(slice.len()))
+							(data, slice.len())
 						} else {
 							self.descend(&node_data)?;
-					Ok(())
+							return Ok(())
 						}
 					},
 					Node::Branch(ref nodes, _) => match key.is_empty() {
@ -256,7 +258,7 @@ impl<'a> TrieDBIterator<'a> {
 								status: Status::At,
 								node: node.clone().into(),
 							});
-					Ok(())
+							return Ok(())
 						},
 						false => {
 							let i = key.at(0);
@ -266,10 +268,15 @@ impl<'a> TrieDBIterator<'a> {
 							});
 							self.key_nibbles.push(i);
 							let child = self.db.get_raw_or_lookup(&*nodes[i as usize])?;
-					self.seek_descend(child, &key.mid(1))
+							(child, 1)
 						}
 					},
-			_ => Ok(())
+					_ => return Ok(()),
+				}
+			};
+
+			node_data = data;
+			key = key.mid(mid);
 		}
 	}

@ -314,7 +321,7 @@ impl<'a> TrieIterator for TrieDBIterator<'a> {
 		self.trail.clear();
 		self.key_nibbles.clear();
 		let root_rlp = self.db.root_data()?;
-		self.seek_descend(root_rlp, &NibbleSlice::new(key))
+		self.seek(root_rlp, NibbleSlice::new(key))
 	}
 }

--- a/util/src/triehash.rs
+++ b/util/src/triehash.rs
@ -115,7 +115,7 @@ pub fn sec_trie_root(input: Vec<(Vec<u8>, Vec<u8>)>) -> H256 {
 	let gen_input = input
 		// first put elements into btree to sort them and to remove duplicates
 		.into_iter()
-		.map(|(k, v)| (k.sha3().to_vec(), v))
+		.map(|(k, v)| (k.sha3(), v))
 		.collect::<BTreeMap<_, _>>()
 		// then move them to a vector
 		.into_iter()
@ -155,8 +155,7 @@ fn hex_prefix_encode(nibbles: &[u8], leaf: bool) -> Vec<u8> {
 	let oddness_factor = inlen % 2;
 	// next even number divided by two
 	let reslen = (inlen + 2) >> 1;
-	let mut res = vec![];
-	res.reserve(reslen);
+	let mut res = Vec::with_capacity(reslen);

 	let first_byte = {
 		let mut bits = ((inlen as u8 & 1) + (2 * leaf as u8)) << 4;
@ -180,11 +179,11 @@ fn hex_prefix_encode(nibbles: &[u8], leaf: bool) -> Vec<u8> {

 /// Converts slice of bytes to nibbles.
 fn as_nibbles(bytes: &[u8]) -> Vec<u8> {
-	let mut res = vec![];
-	res.reserve(bytes.len() * 2);
+	let mut res = Vec::with_capacity(bytes.len() * 2);
 	for i in 0..bytes.len() {
-		res.push(bytes[i] >> 4);
-		res.push((bytes[i] << 4) >> 4);
+		let byte = bytes[i];
+		res.push(byte >> 4);
+		res.push(byte & 0b1111);
 	}
 	res
 }