Introduce basic skeleton for Polkadot runtime. (#32)

* Introduce basic skeleton for Polkador runtime. * Clean up the runtime skeleton. * Make initial runtime skeleton compile. * Compile polkadot-runtime both for Wasm ad native, allowing for testing and direct usage. * More fleshing out on runtime. * Update native support. * Fix warning. * Update gitignore * Update path. * Fix path. * Remove accidentally committed files. * Add wasm binaries. * Fix test. * Native storage support API. * Add environmental module * Add native environment to make native source-code compatible with wasm. Also tests. * Finish up & polish environment stuff. * Avoid using reentrancy issues. * Add some docs and a test. * Remove unneeded function. * Documentation * Tweak docs * Remove TODOs. * Balance transfers + util methods. * Rejig tests and ensure authorities are addressed consistently. * Add marshaller for xfer function * Transaction dispatch test. * Minor fix. * Add test for ser/de transaction. * Add ser/de for header. * Add tests for header ser/de * Introduce basic block decoding/execution framework. * Introduce block decoding/execution framework (p2) * Big refactor. * Split out joiner. * Hide away support modules. * Fix up wasm runtime. * use externalities for chain_id * Clean up (Test)Externalities. * Repot and introduce keccak-256 external. * Signing with crypto. * fix unsafety hole in environmental using function * Introduce Ed25519 crypto. * Repotting. * Add ed25519_verify external. * Introduce Ed25519 verify as an external. * fix unsafety hole around unwinding * Compile fixes. * use new environmental API * Tests for ed25519 verify. * Polish * Introduce UncheckedTransaction & test. * Implement basic block and tx processing * Introduce static hex and valid signature for block test. * Repot session. * comments. * Refactor and timestamp test * Remove fluff * Remove fluff. * Staking eras and tests. * Implement sessions. * Polish * Test sessions. * Introduce better hashing. - Blake2 for secure hashing - XX for fast hashing * Fix tests. * Introduce staking. * Tests for simple staking system. * Build fix for wasm. * Fix tests. * Repotting and docs. * Docs and licence. * Documentation. * Remove superfluous code. * Remove dummy key. * Remove other superfluous file. * Optimise with swap_remove
2026-06-13 18:41:05 +00:00 · 2018-01-23 15:24:17 +01:00
parent 28d84d8ac4
commit 3402f169a7
70 changed files with 3578 additions and 282 deletions
@@ -0,0 +1,44 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot 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.
+
+// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Conensus module for runtime; manages the authority set ready for the native code.
+
+use runtime_support::Vec;
+use storable::StorageVec;
+use primitives::SessionKey;
+
+struct AuthorityStorageVec {}
+impl StorageVec for AuthorityStorageVec {
+	type Item = SessionKey;
+	const PREFIX: &'static[u8] = b"con:aut:";
+}
+
+/// Get the current set of authorities. These are the session keys.
+pub fn authorities() -> Vec<SessionKey> {
+	AuthorityStorageVec::items()
+}
+
+/// Set the current set of authorities' session keys.
+///
+/// Called by `next_session` only.
+pub fn set_authorities(authorities: &[SessionKey]) {
+	AuthorityStorageVec::set_items(authorities);
+}
+
+/// Set a single authority by index.
+pub fn set_authority(index: u32, key: &SessionKey) {
+	AuthorityStorageVec::set_item(index, key);
+}
@@ -0,0 +1,30 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot 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.
+
+// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! The Polkadot runtime.
+
+#[allow(unused)]
+pub mod system;
+#[allow(unused)]
+pub mod consensus;
+#[allow(unused)]
+pub mod staking;
+#[allow(unused)]
+pub mod timestamp;
+#[allow(unused)]
+pub mod session;
+
+// TODO: governance, polkadao
@@ -0,0 +1,229 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot 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.
+
+// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Session manager: is told the validators and allows them to manage their session keys for the
+//! consensus module.
+
+use runtime_support::Vec;
+use keyedvec::KeyedVec;
+use storable::{kill, Storable, StorageVec};
+use primitives::{AccountID, SessionKey, BlockNumber};
+use runtime::{system, staking, consensus};
+
+struct ValidatorStorageVec {}
+impl StorageVec for ValidatorStorageVec {
+	type Item = AccountID;
+	const PREFIX: &'static[u8] = b"ses:val:";
+}
+
+// TRANSACTION API (available to all transactors)
+
+/// Sets the session key of `_validator` to `_key`. This doesn't take effect until the next
+/// session.
+pub fn set_key(validator: &AccountID, key: &SessionKey) {
+	// set new value for next session
+	key.store(&validator.to_keyed_vec(b"ses:nxt:"));
+}
+
+// PUBLIC API (available to other runtime modules)
+
+/// Get the current set of authorities. These are the session keys.
+pub fn validators() -> Vec<AccountID> {
+	ValidatorStorageVec::items()
+}
+
+/// Set the current set of validators.
+///
+/// Called by staking::next_era() only. `next_session` should be called after this in order to
+/// update the session keys to the next validator set.
+pub fn set_validators(new: &[AccountID]) {
+	ValidatorStorageVec::set_items(new);
+	consensus::set_authorities(new);
+}
+
+/// The number of blocks in each session.
+pub fn length() -> BlockNumber {
+	Storable::lookup_default(b"ses:len")
+}
+
+/// The current era index.
+pub fn current_index() -> BlockNumber {
+	Storable::lookup_default(b"ses:ind")
+}
+
+/// Set the current era index.
+pub fn set_current_index(new: BlockNumber) {
+	new.store(b"ses:ind");
+}
+
+/// The block number at which the era length last changed.
+pub fn last_length_change() -> BlockNumber {
+	Storable::lookup_default(b"ses:llc")
+}
+
+/// Set a new era length. Won't kick in until the next era change (at current length).
+pub fn set_length(new: BlockNumber) {
+	new.store(b"ses:nln");
+}
+
+/// Hook to be called after transaction processing.
+pub fn check_rotate_session() {
+	// do this last, after the staking system has had chance to switch out the authorities for the
+	// new set.
+	// check block number and call next_session if necessary.
+	if (system::block_number() - last_length_change()) % length() == 0 {
+		rotate_session();
+	}
+}
+
+// PRIVATE (not available for use externally)
+
+/// Move onto next session: register the new authority set.
+fn rotate_session() {
+	// Increment current session index.
+	set_current_index(current_index() + 1);
+
+	// Enact era length change.
+	if let Some(next_len) = u64::lookup(b"ses:nln") {
+		next_len.store(b"ses:len");
+		system::block_number().store(b"ses:llc");
+		kill(b"ses:nln");
+	}
+
+	// Update any changes in session keys.
+	validators().iter().enumerate().for_each(|(i, v)| {
+		let k = v.to_keyed_vec(b"ses:nxt:");
+		if let Some(n) = Storable::lookup(&k) {
+			consensus::set_authority(i as u32, &n);
+			kill(&k);
+		}
+	});
+}
+
+#[cfg(test)]
+mod tests {
+	use runtime_support::{with_externalities, twox_128};
+	use keyedvec::KeyedVec;
+	use joiner::Joiner;
+	use testing::{one, two, TestExternalities};
+	use primitives::AccountID;
+	use runtime::{consensus, session};
+	use environment::with_env;
+
+	fn simple_setup() -> TestExternalities {
+		TestExternalities { storage: map![
+			twox_128(b"ses:len").to_vec() => vec![].join(&2u64),
+			// the validators (10, 20, ...)
+			twox_128(b"ses:val:len").to_vec() => vec![].join(&2u32),
+			twox_128(&0u32.to_keyed_vec(b"ses:val:")).to_vec() => vec![10; 32],
+			twox_128(&1u32.to_keyed_vec(b"ses:val:")).to_vec() => vec![20; 32],
+			// initial session keys (11, 21, ...)
+			twox_128(b"con:aut:len").to_vec() => vec![].join(&2u32),
+			twox_128(&0u32.to_keyed_vec(b"con:aut:")).to_vec() => vec![11; 32],
+			twox_128(&1u32.to_keyed_vec(b"con:aut:")).to_vec() => vec![21; 32]
+		], }
+	}
+
+	#[test]
+	fn simple_setup_should_work() {
+		let mut t = simple_setup();
+		with_externalities(&mut t, || {
+			assert_eq!(consensus::authorities(), vec![[11u8; 32], [21u8; 32]]);
+			assert_eq!(session::length(), 2u64);
+			assert_eq!(session::validators(), vec![[10u8; 32], [20u8; 32]]);
+		});
+	}
+
+	#[test]
+	fn session_length_change_should_work() {
+		let mut t = simple_setup();
+		with_externalities(&mut t, || {
+			// Block 1: Change to length 3; no visible change.
+			with_env(|e| e.block_number = 1);
+			session::set_length(3);
+			session::check_rotate_session();
+			assert_eq!(session::length(), 2);
+			assert_eq!(session::current_index(), 0);
+
+			// Block 2: Length now changed to 3. Index incremented.
+			with_env(|e| e.block_number = 2);
+			session::set_length(3);
+			session::check_rotate_session();
+			assert_eq!(session::length(), 3);
+			assert_eq!(session::current_index(), 1);
+
+			// Block 3: Length now changed to 3. Index incremented.
+			with_env(|e| e.block_number = 3);
+			session::check_rotate_session();
+			assert_eq!(session::length(), 3);
+			assert_eq!(session::current_index(), 1);
+
+			// Block 4: Change to length 2; no visible change.
+			with_env(|e| e.block_number = 4);
+			session::set_length(2);
+			session::check_rotate_session();
+			assert_eq!(session::length(), 3);
+			assert_eq!(session::current_index(), 1);
+
+			// Block 5: Length now changed to 2. Index incremented.
+			with_env(|e| e.block_number = 5);
+			session::check_rotate_session();
+			assert_eq!(session::length(), 2);
+			assert_eq!(session::current_index(), 2);
+
+			// Block 6: No change.
+			with_env(|e| e.block_number = 6);
+			session::check_rotate_session();
+			assert_eq!(session::length(), 2);
+			assert_eq!(session::current_index(), 2);
+
+			// Block 7: Next index.
+			with_env(|e| e.block_number = 7);
+			session::check_rotate_session();
+			assert_eq!(session::length(), 2);
+			assert_eq!(session::current_index(), 3);
+		});
+	}
+
+	#[test]
+	fn session_change_should_work() {
+		let mut t = simple_setup();
+		with_externalities(&mut t, || {
+			// Block 1: No change
+			with_env(|e| e.block_number = 1);
+			session::check_rotate_session();
+			assert_eq!(consensus::authorities(), vec![[11u8; 32], [21u8; 32]]);
+
+			// Block 2: Session rollover, but no change.
+			with_env(|e| e.block_number = 2);
+			session::check_rotate_session();
+			assert_eq!(consensus::authorities(), vec![[11u8; 32], [21u8; 32]]);
+
+			// Block 3: Set new key for validator 2; no visible change.
+			with_env(|e| e.block_number = 3);
+			session::set_key(&[20; 32], &[22; 32]);
+			assert_eq!(consensus::authorities(), vec![[11u8; 32], [21u8; 32]]);
+
+			session::check_rotate_session();
+			assert_eq!(consensus::authorities(), vec![[11u8; 32], [21u8; 32]]);
+
+			// Block 4: Session rollover, authority 2 changes.
+			with_env(|e| e.block_number = 4);
+			session::check_rotate_session();
+			assert_eq!(consensus::authorities(), vec![[11u8; 32], [22u8; 32]]);
+		});
+	}
+}
@@ -0,0 +1,363 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot 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.
+
+// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Staking manager: Handles balances and periodically determines the best set of validators.
+
+use runtime_support::Vec;
+use keyedvec::KeyedVec;
+use storable::{Storable, StorageVec};
+use primitives::{BlockNumber, AccountID};
+use runtime::{system, session};
+
+/// The balance of an account.
+pub type Balance = u64;
+
+/// The amount of bonding period left in an account. Measured in eras.
+pub type Bondage = u64;
+
+struct IntentionStorageVec {}
+impl StorageVec for IntentionStorageVec {
+	type Item = AccountID;
+	const PREFIX: &'static[u8] = b"ses:wil:";
+}
+
+// Each identity's stake may be in one of three bondage states, given by an integer:
+// - n | n <= current_era(): inactive: free to be transferred.
+// - ~0: active: currently representing a validator.
+// - n | n > current_era(): deactivating: recently representing a validator and not yet
+//   ready for transfer.
+
+/// The length of the bonding duration in eras.
+pub fn bonding_duration() -> BlockNumber {
+	Storable::lookup_default(b"sta:loc")
+}
+
+/// The length of a staking era in sessions.
+pub fn validator_count() -> usize {
+	u32::lookup_default(b"sta:vac") as usize
+}
+
+/// The length of a staking era in blocks.
+pub fn era_length() -> BlockNumber {
+	sessions_per_era() * session::length()
+}
+
+/// The length of a staking era in sessions.
+pub fn sessions_per_era() -> BlockNumber {
+	Storable::lookup_default(b"sta:spe")
+}
+
+/// The current era index.
+pub fn current_era() -> BlockNumber {
+	Storable::lookup_default(b"sta:era")
+}
+
+/// The block number at which the era length last changed.
+pub fn last_era_length_change() -> BlockNumber {
+	Storable::lookup_default(b"sta:lec")
+}
+
+/// The balance of a given account.
+pub fn balance(who: &AccountID) -> Balance {
+	Storable::lookup_default(&who.to_keyed_vec(b"sta:bal:"))
+}
+
+/// The liquidity-state of a given account.
+pub fn bondage(who: &AccountID) -> Bondage {
+	Storable::lookup_default(&who.to_keyed_vec(b"sta:bon:"))
+}
+
+/// Transfer some unlocked staking balance to another staker.
+pub fn transfer(transactor: &AccountID, dest: &AccountID, value: Balance) {
+	let from_key = transactor.to_keyed_vec(b"sta:bal:");
+	let from_balance = Balance::lookup_default(&from_key);
+	assert!(from_balance >= value);
+	let to_key = dest.to_keyed_vec(b"sta:bal:");
+	let to_balance: Balance = Storable::lookup_default(&to_key);
+	assert!(bondage(transactor) <= bondage(dest));
+	assert!(to_balance + value > to_balance);	// no overflow
+	(from_balance - value).store(&from_key);
+	(to_balance + value).store(&to_key);
+}
+
+/// Declare the desire to stake for the transactor.
+///
+/// Effects will be felt at the beginning of the next era.
+pub fn stake(transactor: &AccountID) {
+	let mut intentions = IntentionStorageVec::items();
+	// can't be in the list twice.
+	assert!(intentions.iter().find(|t| *t == transactor).is_none(), "Cannot stake if already staked.");
+	intentions.push(transactor.clone());
+	IntentionStorageVec::set_items(&intentions);
+	u64::max_value().store(&transactor.to_keyed_vec(b"sta:bon:"));
+}
+
+/// Retract the desire to stake for the transactor.
+///
+/// Effects will be felt at the beginning of the next era.
+pub fn unstake(transactor: &AccountID) {
+	let mut intentions = IntentionStorageVec::items();
+	if let Some(position) = intentions.iter().position(|t| t == transactor) {
+		intentions.swap_remove(position);
+	} else {
+		panic!("Cannot unstake if not already staked.");
+	}
+	IntentionStorageVec::set_items(&intentions);
+	(current_era() + bonding_duration()).store(&transactor.to_keyed_vec(b"sta:bon:"));
+}
+
+/// Hook to be called after to transaction processing.
+pub fn check_new_era() {
+	// check block number and call new_era if necessary.
+	if (system::block_number() - last_era_length_change()) % era_length() == 0 {
+		new_era();
+	}
+}
+
+// PRIVATE
+
+/// The era has changed - enact new staking set.
+///
+/// NOTE: This always happens on a session change.
+fn new_era() {
+	// Increment current era.
+	(current_era() + 1).store(b"sta:era");
+
+	// Enact era length change.
+	let next_spe: u64 = Storable::lookup_default(b"sta:nse");
+	if next_spe > 0 && next_spe != sessions_per_era() {
+		next_spe.store(b"sta:spe");
+		system::block_number().store(b"sta:lec");
+	}
+
+	// TODO: evaluate desired staking amounts and nominations and optimise to find the best
+	// combination of validators, then use session::set_validators().
+
+	// for now, this just orders would-be stakers by their balances and chooses the top-most
+	// validator_count() of them.
+	let mut intentions = IntentionStorageVec::items()
+		.into_iter()
+		.map(|v| (balance(&v), v))
+		.collect::<Vec<_>>();
+	intentions.sort_unstable_by(|&(b1, _), &(b2, _)| b2.cmp(&b1));
+	session::set_validators(
+		&intentions.into_iter()
+			.map(|(_, v)| v)
+			.take(validator_count())
+			.collect::<Vec<_>>()
+	);
+}
+
+/// Set a new era length. Won't kick in until the next era change (at current length).
+fn set_sessions_per_era(new: BlockNumber) {
+	new.store(b"sta:nse");
+}
+
+#[cfg(test)]
+mod tests {
+	use runtime_support::{with_externalities, twox_128};
+	use keyedvec::KeyedVec;
+	use joiner::Joiner;
+	use testing::{one, two, TestExternalities};
+	use primitives::AccountID;
+	use runtime::{staking, session};
+	use environment::with_env;
+
+	#[test]
+	fn staking_should_work() {
+		let one = one();
+		let two = two();
+		let three = [3u8; 32];
+		let four = [4u8; 32];
+
+		let mut t = TestExternalities { storage: map![
+			twox_128(b"ses:len").to_vec() => vec![].join(&1u64),
+			twox_128(b"ses:val:len").to_vec() => vec![].join(&2u32),
+			twox_128(&0u32.to_keyed_vec(b"ses:val:")).to_vec() => vec![10; 32],
+			twox_128(&1u32.to_keyed_vec(b"ses:val:")).to_vec() => vec![20; 32],
+			twox_128(b"sta:spe").to_vec() => vec![].join(&2u64),
+			twox_128(b"sta:vac").to_vec() => vec![].join(&2u32),
+			twox_128(b"sta:loc").to_vec() => vec![].join(&3u64),
+			twox_128(&one.to_keyed_vec(b"sta:bal:")).to_vec() => vec![].join(&10u64),
+			twox_128(&two.to_keyed_vec(b"sta:bal:")).to_vec() => vec![].join(&20u64),
+			twox_128(&three.to_keyed_vec(b"sta:bal:")).to_vec() => vec![].join(&30u64),
+			twox_128(&four.to_keyed_vec(b"sta:bal:")).to_vec() => vec![].join(&40u64)
+		], };
+
+		with_externalities(&mut t, || {
+			assert_eq!(staking::era_length(), 2u64);
+			assert_eq!(staking::validator_count(), 2usize);
+			assert_eq!(staking::bonding_duration(), 3u64);
+			assert_eq!(session::validators(), vec![[10u8; 32], [20u8; 32]]);
+
+			// Block 1: Add three validators. No obvious change.
+			with_env(|e| e.block_number = 1);
+			staking::stake(&one);
+			staking::stake(&two);
+			staking::stake(&four);
+			staking::check_new_era();
+			assert_eq!(session::validators(), vec![[10u8; 32], [20u8; 32]]);
+
+			// Block 2: New validator set now.
+			with_env(|e| e.block_number = 2);
+			staking::check_new_era();
+			assert_eq!(session::validators(), vec![four.clone(), two.clone()]);
+
+			// Block 3: Unstake highest, introduce another staker. No change yet.
+			with_env(|e| e.block_number = 3);
+			staking::stake(&three);
+			staking::unstake(&four);
+			staking::check_new_era();
+
+			// Block 4: New era - validators change.
+			with_env(|e| e.block_number = 4);
+			staking::check_new_era();
+			assert_eq!(session::validators(), vec![three.clone(), two.clone()]);
+
+			// Block 5: Transfer stake from highest to lowest. No change yet.
+			with_env(|e| e.block_number = 5);
+			staking::transfer(&four, &one, 40);
+			staking::check_new_era();
+
+			// Block 6: Lowest now validator.
+			with_env(|e| e.block_number = 6);
+			staking::check_new_era();
+			assert_eq!(session::validators(), vec![one.clone(), three.clone()]);
+
+			// Block 7: Unstake three. No change yet.
+			with_env(|e| e.block_number = 7);
+			staking::unstake(&three);
+			staking::check_new_era();
+			assert_eq!(session::validators(), vec![one.clone(), three.clone()]);
+
+			// Block 8: Back to one and two.
+			with_env(|e| e.block_number = 8);
+			staking::check_new_era();
+			assert_eq!(session::validators(), vec![one.clone(), two.clone()]);
+		});
+	}
+
+	#[test]
+	fn staking_eras_work() {
+		let mut t = TestExternalities { storage: map![
+			twox_128(b"ses:len").to_vec() => vec![].join(&1u64),
+			twox_128(b"sta:spe").to_vec() => vec![].join(&2u64)
+		], };
+		with_externalities(&mut t, || {
+			assert_eq!(staking::era_length(), 2u64);
+			assert_eq!(staking::sessions_per_era(), 2u64);
+			assert_eq!(staking::last_era_length_change(), 0u64);
+			assert_eq!(staking::current_era(), 0u64);
+
+			// Block 1: No change.
+			with_env(|e| e.block_number = 1);
+			staking::check_new_era();
+			assert_eq!(staking::sessions_per_era(), 2u64);
+			assert_eq!(staking::last_era_length_change(), 0u64);
+			assert_eq!(staking::current_era(), 0u64);
+
+			// Block 2: Simple era change.
+			with_env(|e| e.block_number = 2);
+			staking::check_new_era();
+			assert_eq!(staking::sessions_per_era(), 2u64);
+			assert_eq!(staking::last_era_length_change(), 0u64);
+			assert_eq!(staking::current_era(), 1u64);
+
+			// Block 3: Schedule an era length change; no visible changes.
+			with_env(|e| e.block_number = 3);
+			staking::set_sessions_per_era(3);
+			staking::check_new_era();
+			assert_eq!(staking::sessions_per_era(), 2u64);
+			assert_eq!(staking::last_era_length_change(), 0u64);
+			assert_eq!(staking::current_era(), 1u64);
+
+			// Block 4: Era change kicks in.
+			with_env(|e| e.block_number = 4);
+			staking::check_new_era();
+			assert_eq!(staking::sessions_per_era(), 3u64);
+			assert_eq!(staking::last_era_length_change(), 4u64);
+			assert_eq!(staking::current_era(), 2u64);
+
+			// Block 5: No change.
+			with_env(|e| e.block_number = 5);
+			staking::check_new_era();
+			assert_eq!(staking::sessions_per_era(), 3u64);
+			assert_eq!(staking::last_era_length_change(), 4u64);
+			assert_eq!(staking::current_era(), 2u64);
+
+			// Block 6: No change.
+			with_env(|e| e.block_number = 6);
+			staking::check_new_era();
+			assert_eq!(staking::sessions_per_era(), 3u64);
+			assert_eq!(staking::last_era_length_change(), 4u64);
+			assert_eq!(staking::current_era(), 2u64);
+
+			// Block 7: Era increment.
+			with_env(|e| e.block_number = 7);
+			staking::check_new_era();
+			assert_eq!(staking::sessions_per_era(), 3u64);
+			assert_eq!(staking::last_era_length_change(), 4u64);
+			assert_eq!(staking::current_era(), 3u64);
+		});
+	}
+
+	#[test]
+	fn staking_balance_works() {
+		let one = one();
+		let two = two();
+
+		let mut t = TestExternalities { storage: map![
+			twox_128(&one.to_keyed_vec(b"sta:bal:")).to_vec() => vec![].join(&42u64)
+		], };
+
+		with_externalities(&mut t, || {
+			assert_eq!(staking::balance(&one), 42);
+			assert_eq!(staking::balance(&two), 0);
+		});
+	}
+
+	#[test]
+	fn staking_balance_transfer_works() {
+		let one = one();
+		let two = two();
+
+		let mut t = TestExternalities { storage: map![
+			twox_128(&one.to_keyed_vec(b"sta:bal:")).to_vec() => vec![].join(&111u64)
+		], };
+
+		with_externalities(&mut t, || {
+			staking::transfer(&one, &two, 69);
+			assert_eq!(staking::balance(&one), 42);
+			assert_eq!(staking::balance(&two), 69);
+		});
+	}
+
+	#[test]
+	#[should_panic]
+	fn staking_balance_transfer_when_bonded_doesnt_work() {
+		let one = one();
+		let two = two();
+
+		let mut t = TestExternalities { storage: map![
+			twox_128(&one.to_keyed_vec(b"sta:bal:")).to_vec() => vec![].join(&111u64)
+		], };
+
+		with_externalities(&mut t, || {
+			staking::stake(&one);
+			staking::transfer(&one, &two, 69);
+		});
+	}
+}
@@ -0,0 +1,154 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot 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.
+
+// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! System manager: Handles all of the top-level stuff; executing block/transaction, setting code
+//! and depositing logs.
+
+use primitives::{Block, BlockNumber, Hash, UncheckedTransaction, TxOrder, Hashable};
+use runtime_support::{Vec, swap};
+use storable::Storable;
+use keyedvec::KeyedVec;
+use environment::with_env;
+use runtime::{staking, session};
+
+/// The current block number being processed. Set by `execute_block`.
+pub fn block_number() -> BlockNumber {
+	with_env(|e| e.block_number)
+}
+
+/// Get the block hash of a given block (uses storage).
+pub fn block_hash(number: BlockNumber) -> Hash {
+	Storable::lookup_default(&number.to_keyed_vec(b"sys:old:"))
+}
+
+/// Deposits a log and ensures it matches the blocks log data.
+pub fn deposit_log(log: &[u8]) {
+	with_env(|e| {
+		assert_eq!(log, &e.digest.logs[e.next_log_index][..]);
+		e.next_log_index += 1;
+	});
+}
+
+pub fn execute_block(mut block: Block) {
+	// populate environment from header.
+	with_env(|e| {
+		e.block_number = block.header.number;
+		swap(&mut e.digest, &mut block.header.digest);
+		e.next_log_index = 0;
+	});
+
+	let ref header = block.header;
+
+	// check parent_hash is correct.
+	assert!(
+		header.number > 0 && block_hash(header.number - 1) == header.parent_hash,
+		"Parent hash should be valid."
+	);
+
+	// TODO: check transaction trie root represents the transactions.
+	// this requires non-trivial changes to the externals API or compiling trie rooting into wasm
+	// so will wait until a little later.
+
+	// store the header hash in storage.
+	let header_hash_key = header.number.to_keyed_vec(b"sys:old:");
+	header.blake2_256().store(&header_hash_key);
+
+	// execute transactions
+	block.transactions.iter().for_each(execute_transaction);
+
+	staking::check_new_era();
+	session::check_rotate_session();
+
+	// any final checks
+	final_checks(&block);
+
+	// TODO: check storage root.
+	// this requires non-trivial changes to the externals API or compiling trie rooting into wasm
+	// so will wait until a little later.
+}
+
+/// Execute a given transaction.
+pub fn execute_transaction(utx: &UncheckedTransaction) {
+	// Verify the signature is good.
+	assert!(utx.ed25519_verify(), "All transactions should be properly signed");
+
+	let ref tx = utx.transaction;
+
+	// check nonce
+	let nonce_key = tx.signed.to_keyed_vec(b"sys:non:");
+	let expected_nonce: TxOrder = Storable::lookup_default(&nonce_key);
+	assert!(tx.nonce == expected_nonce, "All transactions should have the correct nonce");
+
+	// increment nonce in storage
+	(expected_nonce + 1).store(&nonce_key);
+
+	// decode parameters and dispatch
+	tx.function.dispatch(&tx.signed, &tx.input_data);
+}
+
+/// Set the new code.
+pub fn set_code(new: &[u8]) {
+	new.store(b":code");
+}
+
+fn final_checks(_block: &Block) {
+	with_env(|e| {
+		assert_eq!(e.next_log_index, e.digest.logs.len());
+	});
+}
+
+#[cfg(test)]
+mod tests {
+	use joiner::Joiner;
+	use function::Function;
+	use keyedvec::KeyedVec;
+	use slicable::Slicable;
+	use runtime_support::{with_externalities, twox_128};
+	use primitives::{UncheckedTransaction, Transaction};
+	use statichex::StaticHexInto;
+	use runtime::{system, staking};
+	use testing::{TestExternalities, HexDisplay, one, two};
+
+	#[test]
+	fn staking_balance_transfer_dispatch_works() {
+		let one = one();
+		let two = two();
+
+		let mut t = TestExternalities { storage: map![
+			twox_128(&one.to_keyed_vec(b"sta:bal:")).to_vec() => vec![111u8, 0, 0, 0, 0, 0, 0, 0]
+		], };
+
+		let tx = UncheckedTransaction {
+			transaction: Transaction {
+				signed: one.clone(),
+				nonce: 0,
+				function: Function::StakingTransfer,
+				input_data: vec![].join(&two).join(&69u64),
+			},
+			signature: "679fcf0a846b4224c84ecad7d91a26241c46d00cb53d6480a363274e8965ee34b0b80b4b2e3836d3d8f8f12c0c1aef7350af587d9aee3883561d11726068ac0a".convert(),
+		};
+		// tx: 2f8c6129d816cf51c374bc7f08c3e63ed156cf78aefb4a6550d97b87997977ee00000000000000000228000000d75a980182b10ab7d54bfed3c964073a0ee172f3daa62325af021a68f707511a4500000000000000
+		// sig: 679fcf0a846b4224c84ecad7d91a26241c46d00cb53d6480a363274e8965ee34b0b80b4b2e3836d3d8f8f12c0c1aef7350af587d9aee3883561d11726068ac0a
+
+		println!("tx is {}", HexDisplay::from(&tx.transaction.to_vec()));
+
+		with_externalities(&mut t, || {
+			system::execute_transaction(&tx);
+			assert_eq!(staking::balance(&one), 42);
+			assert_eq!(staking::balance(&two), 69);
+		});
+	}
+}
@@ -0,0 +1,54 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot 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.
+
+// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Timestamp manager: just handles the current timestamp.
+
+use storable::Storable;
+
+/// Representation of a time.
+pub type Timestamp = u64;
+
+/// Get the current time.
+pub fn get() -> Timestamp {
+	Storable::lookup_default(b"tim:val")
+}
+
+/// Set the current time.
+pub fn set(now: Timestamp) {
+	now.store(b"tim:val")
+}
+
+#[cfg(test)]
+mod tests {
+	use joiner::Joiner;
+	use keyedvec::KeyedVec;
+	use runtime_support::{with_externalities, twox_128};
+	use runtime::timestamp;
+	use testing::TestExternalities;
+
+	#[test]
+	fn timestamp_works() {
+		let mut t = TestExternalities { storage: map![
+			twox_128(b"tim:val").to_vec() => vec![].join(&42u64)
+		], };
+
+		with_externalities(&mut t, || {
+			assert_eq!(timestamp::get(), 42);
+			timestamp::set(69);
+			assert_eq!(timestamp::get(), 69);
+		});
+	}
+}