Merge branch 'master' into blockchain

2015-12-21 02:34:41 +01:00 · 2015-12-21 02:34:41 +01:00 · 0164ce4b19
parent c2a799064d 49b407c735
commit 0164ce4b19
16 changed files with 659 additions and 151 deletions
--- a/src/account.rs
+++ b/src/account.rs
@ -6,10 +6,12 @@ use util::bytes::*;
 use util::trie::*;
 use util::rlp::*;
 use util::uint::*;
+use std::cell::*;

 pub const SHA3_EMPTY: H256 = H256( [0xc5, 0xd2, 0x46, 0x01, 0x86, 0xf7, 0x23, 0x3c, 0x92, 0x7e, 0x7d, 0xb2, 0xdc, 0xc7, 0x03, 0xc0, 0xe5, 0x00, 0xb6, 0x53, 0xca, 0x82, 0x27, 0x3b, 0x7b, 0xfa, 0xd8, 0x04, 0x5d, 0x85, 0xa4, 0x70] );

 /// Single account in the system.
+#[derive(Debug)]
 pub struct Account {
 	// Balance of the account.
 	balance: U256,
@ -18,7 +20,7 @@ pub struct Account {
 	// Trie-backed storage.
 	storage_root: H256,
 	// Overlay on trie-backed storage.
-	storage_overlay: HashMap<H256, H256>,
+	storage_overlay: RefCell<HashMap<H256, H256>>,
 	// Code hash of the account. If None, means that it's a contract whose code has not yet been set.
 	code_hash: Option<H256>,
 	// Code cache of the account.
@ -32,19 +34,19 @@ impl Account {
 			balance: balance,
 			nonce: nonce,
 			storage_root: SHA3_NULL_RLP,
-			storage_overlay: storage,
+			storage_overlay: RefCell::new(storage),
 			code_hash: Some(code.sha3()),
 			code_cache: code
 		}
 	}

 	/// Create a new account with the given balance.
-	pub fn new_basic(balance: U256) -> Account {
+	pub fn new_basic(balance: U256, nonce: U256) -> Account {
 		Account {
 			balance: balance,
-			nonce: U256::from(0u8),
+			nonce: nonce,
 			storage_root: SHA3_NULL_RLP,
-			storage_overlay: HashMap::new(),
+			storage_overlay: RefCell::new(HashMap::new()),
 			code_hash: Some(SHA3_EMPTY),
 			code_cache: vec![],
 		}
@ -57,7 +59,7 @@ impl Account {
 			nonce: r.val_at(0),
 			balance: r.val_at(1),
 			storage_root: r.val_at(2),
-			storage_overlay: HashMap::new(),
+			storage_overlay: RefCell::new(HashMap::new()),
 			code_hash: Some(r.val_at(3)),
 			code_cache: vec![],
 		}
@ -70,7 +72,7 @@ impl Account {
 			balance: balance,
 			nonce: U256::from(0u8),
 			storage_root: SHA3_NULL_RLP,
-			storage_overlay: HashMap::new(),
+			storage_overlay: RefCell::new(HashMap::new()),
 			code_hash: None,
 			code_cache: vec![],
 		}
@ -85,20 +87,14 @@ impl Account {

 	/// Set (and cache) the contents of the trie's storage at `key` to `value`.
 	pub fn set_storage(&mut self, key: H256, value: H256) {
-		self.storage_overlay.insert(key, value);
+		self.storage_overlay.borrow_mut().insert(key, value);
 	}

 	/// Get (and cache) the contents of the trie's storage at `key`.
-	pub fn storage_at(&mut self, db: &mut HashDB, key: H256) -> H256 {
-		match self.storage_overlay.get(&key) {
-			Some(x) => { return x.clone() },
-			_ => {}
-		}
-		// fetch - cannot be done in match because of the borrow rules.
-		let t = TrieDB::new_existing(db, &mut self.storage_root);
-		let r = H256::from_slice(t.at(key.bytes()).unwrap_or(&[0u8;32][..]));
-		self.storage_overlay.insert(key, r.clone());
-		r
+	pub fn storage_at(&self, db: &HashDB, key: &H256) -> H256 {
+		self.storage_overlay.borrow_mut().entry(key.clone()).or_insert_with(||{
+			H256::from_slice(TrieDB::new(db, &self.storage_root).get(key.bytes()).unwrap_or(&[0u8;32][..]))
+		}).clone()
 	}

 	/// return the balance associated with this account.
@ -118,6 +114,7 @@ impl Account {
 		match self.code_hash {
 			Some(SHA3_EMPTY) | None if self.code_cache.is_empty() => Some(&self.code_cache),
 			Some(_) if !self.code_cache.is_empty() => Some(&self.code_cache),
+			None => Some(&self.code_cache),
 			_ => None,
 		}
 	}
@ -140,7 +137,7 @@ impl Account {
 	}

 	/// Provide a database to lookup `code_hash`. Should not be called if it is a contract without code.
-	pub fn ensure_cached(&mut self, db: &HashDB) -> bool {
+	pub fn cache_code(&mut self, db: &HashDB) -> bool {
 		// TODO: fill out self.code_cache;
 /*		return !self.is_cached() ||
 			match db.lookup(&self.code_hash.unwrap()) {	// why doesn't this work? unwrap causes move?!
@ -160,10 +157,10 @@ impl Account {
 	pub fn base_root(&self) -> &H256 { &self.storage_root }
 	
 	/// return the storage root associated with this account or None if it has been altered via the overlay.
-	pub fn storage_root(&self) -> Option<&H256> { if self.storage_overlay.is_empty() {Some(&self.storage_root)} else {None} }
+	pub fn storage_root(&self) -> Option<&H256> { if self.storage_overlay.borrow().is_empty() {Some(&self.storage_root)} else {None} }
 	
 	/// rturn the storage overlay.
-	pub fn storage_overlay(&self) -> &HashMap<H256, H256> { &self.storage_overlay }
+	pub fn storage_overlay(&self) -> Ref<HashMap<H256, H256>> { self.storage_overlay.borrow() }

 	/// Increment the nonce of the account by one.
 	pub fn inc_nonce(&mut self) { self.nonce = self.nonce + U256::from(1u8); }
@ -176,20 +173,24 @@ impl Account {

 	/// Commit the `storage_overlay` to the backing DB and update `storage_root`.
 	pub fn commit_storage(&mut self, db: &mut HashDB) {
-		let mut t = TrieDB::new(db, &mut self.storage_root);
-		for (k, v) in self.storage_overlay.iter() {
+		let mut t = TrieDBMut::new(db, &mut self.storage_root);
+		for (k, v) in self.storage_overlay.borrow().iter() {
 			// cast key and value to trait type,
 			// so we can call overloaded `to_bytes` method
 			t.insert(k, v);
 		}
-		self.storage_overlay.clear();
+		self.storage_overlay.borrow_mut().clear();
 	}

 	/// Commit any unsaved code. `code_hash` will always return the hash of the `code_cache` after this.
 	pub fn commit_code(&mut self, db: &mut HashDB) {
+		println!("Commiting code of {:?} - {:?}, {:?}", self, self.code_hash.is_none(), self.code_cache.is_empty());
 		match (self.code_hash.is_none(), self.code_cache.is_empty()) {
-			(true, true) => self.code_hash = Some(self.code_cache.sha3()),
-			(true, false) => self.code_hash = Some(db.insert(&self.code_cache)),
+			(true, true) => self.code_hash = Some(SHA3_EMPTY),
+			(true, false) => {
+				println!("Writing into DB {:?}", self.code_cache);
+				self.code_hash = Some(db.insert(&self.code_cache));
+			},
 			(false, _) => {},
 		}
 	}
@ -212,7 +213,6 @@ use super::*;
 use std::collections::HashMap;
 use util::hash::*;
 use util::bytes::*;
-use util::trie::*;
 use util::rlp::*;
 use util::uint::*;
 use util::overlaydb::*;
@ -229,10 +229,10 @@ fn storage_at() {
 		a.rlp()
 	};

-	let mut a = Account::from_rlp(&rlp);
+	let a = Account::from_rlp(&rlp);
 	assert_eq!(a.storage_root().unwrap().hex(), "3541f181d6dad5c504371884684d08c29a8bad04926f8ceddf5e279dbc3cc769");
-	assert_eq!(a.storage_at(&mut db, H256::from(&U256::from(0x00u64))), H256::from(&U256::from(0x1234u64)));
-	assert_eq!(a.storage_at(&mut db, H256::from(&U256::from(0x01u64))), H256::new());
+	assert_eq!(a.storage_at(&mut db, &H256::from(&U256::from(0x00u64))), H256::from(&U256::from(0x1234u64)));
+	assert_eq!(a.storage_at(&mut db, &H256::from(&U256::from(0x01u64))), H256::new());
 }

 #[test]
@ -247,7 +247,7 @@ fn note_code() {
 	};

 	let mut a = Account::from_rlp(&rlp);
-	assert_eq!(a.ensure_cached(&db), true);
+	assert_eq!(a.cache_code(&db), true);

 	let mut a = Account::from_rlp(&rlp);
 	assert_eq!(a.note_code(vec![0x55, 0x44, 0xffu8]), Ok(()));
--- a/src/blockchain.rs
+++ b/src/blockchain.rs
@ -13,7 +13,7 @@ use util::hashdb::*;
 use util::sha3::*;
 use util::bytes::*;
 use util::squeeze::*;
-use blockheader::*;
+use header::*;
 use extras::*;
 use transaction::*;
 use views::*;
--- a/src/builtin.rs
+++ b/src/builtin.rs
@ -0,0 +1,10 @@
+use util::uint::*;
+
+/// Definition of a contract whose implementation is built-in. 
+pub struct Builtin {
+	/// The gas cost of running this built-in for the given size of input data.
+	pub cost: Box<Fn(usize) -> U256>,	// TODO: U256 should be bignum.
+	/// Run this built-in function with the input being the first argument and the output
+	/// being placed into the second.
+	pub execute: Box<Fn(&[u8], &mut [u8])>,
+}
--- a/src/engine.rs
+++ b/src/engine.rs
@ -0,0 +1,51 @@
+use std::collections::hash_map::*;
+use util::bytes::*;
+use util::semantic_version::*;
+use util::error::*;
+use header::Header;
+use transaction::Transaction;
+use spec::Spec;
+use evm_schedule::EvmSchedule;
+use env_info::EnvInfo;
+
+/// A consensus mechanism for the chain. Generally either proof-of-work or proof-of-stake-based.
+/// Provides hooks into each of the major parts of block import.
+pub trait Engine {
+	/// The name of this engine.
+	fn name(&self) -> &str;
+	/// The version of this engine. Should be of the form 
+	fn version(&self) -> SemanticVersion { SemanticVersion::new(0, 0, 0) }
+
+	/// The number of additional header fields required for this engine.
+	fn seal_fields(&self) -> u32 { 0 }
+	/// Default values of the additional fields RLP-encoded in a raw (non-list) harness.
+	fn seal_rlp(&self) -> Bytes { vec![] }
+
+	/// Additional engine-specific information for the user/developer concerning `header`.
+	fn extra_info(&self, _header: &Header) -> HashMap<String, String> { HashMap::new() }
+
+	/// Get the general parameters of the chain.
+	fn spec(&self) -> &Spec;
+
+	/// Get the EVM schedule for 
+	fn evm_schedule(&self, env_info: &EnvInfo) -> EvmSchedule;
+
+	/// Verify that `header` is valid.
+	/// `parent` (the parent header) and `block` (the header's full block) may be provided for additional
+	/// checks. Returns either a null `Ok` or a general error detailing the problem with import.
+	fn verify(&self, _header: &Header, _parent: Option<&Header>, _block: Option<&[u8]>) -> Result<(), EthcoreError> { Ok(()) }
+
+	/// Additional verification for transactions in blocks.
+	// TODO: Add flags for which bits of the transaction to check.
+	fn verify_transaction(&self, _t: &Transaction, _header: &Header) -> Result<(), EthcoreError> { Ok(()) }
+
+	/// Don't forget to call Super::populateFromParent when subclassing & overriding.
+	fn populate_from_parent(&self, _header: &mut Header, _parent: &Header) -> Result<(), EthcoreError> { Ok(()) }
+
+	// TODO: buildin contract routing - this will require removing the built-in configuration reading logic from Spec
+	// into here and removing the Spec::builtins field. It's a big job.
+/*	fn is_builtin(&self, a: Address) -> bool;
+	fn cost_of_builtin(&self, a: Address, in: &[u8]) -> bignum;
+	fn execute_builtin(&self, a: Address, in: &[u8], out: &mut [u8]);
+*/
+}
--- a/src/env_info.rs
+++ b/src/env_info.rs
@ -0,0 +1,24 @@
+use util::uint::*;
+use util::hash::*;
+
+/// Simple vector of hashes, should be at most 256 items large, can be smaller if being used
+/// for a block whose number is less than 257.
+pub type LastHashes = Vec<H256>;
+
+/// Information concerning the execution environment for a message-call/contract-creation.
+pub struct EnvInfo {
+	/// The block number.
+	pub number: U256,
+	/// The block author.
+	pub author: Address,
+	/// The block timestamp.
+	pub timestamp: U256,
+	/// The block difficulty.
+	pub difficulty: U256,
+	/// The block gas limit.
+	pub gas_limit: U256,
+	/// The last 256 block hashes.
+	pub last_hashes: LastHashes,
+	/// The gas used.
+	pub gas_used: U256,
+}
--- a/src/evm_schedule.rs
+++ b/src/evm_schedule.rs
@ -0,0 +1,80 @@
+/// Definition of the cost schedule and other parameterisations for the EVM.
+pub struct EvmSchedule {
+	pub exceptional_failed_code_deposit: bool,
+	pub have_delegate_call: bool,
+	pub stack_limit: usize,
+	pub tier_step_gas: [usize; 8],
+	pub exp_gas: usize,
+	pub exp_byte_gas: usize,
+	pub sha3_gas: usize,
+	pub sha3_word_gas: usize,
+	pub sload_gas: usize,
+	pub sstore_set_gas: usize,
+	pub sstore_reset_gas: usize,
+	pub sstore_refund_gas: usize,
+	pub jumpdest_gas: usize,
+	pub log_gas: usize,
+	pub log_data_gas: usize,
+	pub log_topic_gas: usize,
+	pub create_gas: usize,
+	pub call_gas: usize,
+	pub call_stipend: usize,
+	pub call_value_transfer_gas: usize,
+	pub call_new_account_gas: usize,
+	pub suicide_refund_gas: usize,
+	pub memory_gas: usize,
+	pub quad_coeff_div: usize,
+	pub create_data_gas: usize,
+	pub tx_gas: usize,
+	pub tx_create_gas: usize,
+	pub tx_data_zero_gas: usize,
+	pub tx_data_non_zero_gas: usize,
+	pub copy_gas: usize,
+}
+
+impl EvmSchedule {
+	/// Schedule for the Frontier-era of the Ethereum main net.
+	pub fn new_frontier() -> EvmSchedule {
+		Self::new(false, false, 21000)
+	}
+
+	/// Schedule for the Homestead-era of the Ethereum main net.
+	pub fn new_homestead() -> EvmSchedule {
+		Self::new(true, true, 53000)
+	}
+
+	fn new(efcd: bool, hdc: bool, tcg: usize) -> EvmSchedule {
+		EvmSchedule{
+			exceptional_failed_code_deposit: efcd,
+			have_delegate_call: hdc,
+			stack_limit: 1024,
+			tier_step_gas: [0usize, 2, 3, 4, 5, 6, 10, 20],
+			exp_gas: 10,
+			exp_byte_gas: 10,
+			sha3_gas: 30,
+			sha3_word_gas: 6,
+			sload_gas: 50,
+			sstore_set_gas: 20000,
+			sstore_reset_gas: 5000,
+			sstore_refund_gas: 15000,
+			jumpdest_gas: 1,
+			log_gas: 375,
+			log_data_gas: 8,
+			log_topic_gas: 375,
+			create_gas: 32000,
+			call_gas: 40,
+			call_stipend: 2300,
+			call_value_transfer_gas: 9000,
+			call_new_account_gas: 25000,
+			suicide_refund_gas: 24000,
+			memory_gas: 3,
+			quad_coeff_div: 512,
+			create_data_gas: 200,
+			tx_gas: 21000,
+			tx_create_gas: tcg,
+			tx_data_zero_gas: 4,
+			tx_data_non_zero_gas: 68,
+			copy_gas: 3,	
+		}
+	}
+}
--- a/src/genesis.rs
+++ b/src/genesis.rs
@ -10,7 +10,7 @@ use util::hash::*;
 use util::uint::*;
 use util::sha3::*;
 use account::*;
-use blockheader::*;
+use header::*;

 /// Converts file from base64 gzipped bytes to json
 fn base_to_json(source: &[u8]) -> Json {
@ -88,7 +88,7 @@ impl Genesis {
 			let addr = Address::from_str(address).unwrap();
 			let o = acc.as_object().unwrap();
 			let balance = U256::from_dec_str(o["balance"].as_string().unwrap()).unwrap();
-			state.insert(addr, Account::new_basic(balance));
+			state.insert(addr, Account::new_basic(balance, U256::from(0)));
 		}

 		(header, state)
--- a/src/blockheader.rs
+++ b/src/blockheader.rs
--- a/src/lib.rs
+++ b/src/lib.rs
@ -1,3 +1,5 @@
+#![feature(cell_extras)]
+
 //! Ethcore's ethereum implementation
 //! 
 //! ### Rust version
@ -86,19 +88,19 @@ pub use util::hash::*;
 pub use util::uint::*;
 pub use util::bytes::*;

-pub mod account;
-pub mod blockchain;
+pub mod env_info;
+pub mod engine;
 pub mod state;
-pub mod blockheader;
+pub mod account;
+pub mod header;
 pub mod transaction;
-pub mod extras;
+pub mod receipt;
+pub mod denominations;
+pub mod null_engine;
+pub mod evm_schedule;
+pub mod builtin;
+pub mod spec;
 pub mod genesis;
 pub mod views;
-
-pub mod networkparams;
-pub mod denominations;
-
-
-#[test]
-fn it_works() {
-}
+pub mod blockchain;
+pub mod extras;
--- a/src/networkparams.rs
+++ b/src/networkparams.rs
@ -1,71 +0,0 @@
-use util::uint::*;
-use denominations::*;
-
-/// Network related const params
-/// TODO: make it configurable from json file
-pub struct NetworkParams {
-	maximum_extra_data_size: U256,
-	min_gas_limit: U256,
-	gas_limit_bounds_divisor: U256,
-	minimum_difficulty: U256,
-	difficulty_bound_divisor: U256,
-	duration_limit: U256,
-	block_reward: U256,
-	gas_floor_target: U256,
-	account_start_nonce: U256
-}
-
-impl NetworkParams {
-	pub fn olympic() -> NetworkParams {
-		NetworkParams {
-			maximum_extra_data_size: U256::from(1024u64),
-			min_gas_limit: U256::from(125_000u64),
-			gas_floor_target: U256::from(3_141_592u64),
-			gas_limit_bounds_divisor: U256::from(1024u64),
-			minimum_difficulty: U256::from(131_072u64),
-			difficulty_bound_divisor: U256::from(2048u64),
-			duration_limit: U256::from(8u64),
-			block_reward: finney() * U256::from(1500u64),
-			account_start_nonce: U256::from(0u64)
-		}
-	}
-
-	pub fn frontier() -> NetworkParams {
-		NetworkParams {
-			maximum_extra_data_size: U256::from(32u64),
-			min_gas_limit: U256::from(5000u64),
-			gas_floor_target: U256::from(3_141_592u64),
-			gas_limit_bounds_divisor: U256::from(1024u64),
-			minimum_difficulty: U256::from(131_072u64),
-			difficulty_bound_divisor: U256::from(2048u64),
-			duration_limit: U256::from(13u64),
-			block_reward: ether() * U256::from(5u64),
-			account_start_nonce: U256::from(0u64)
-		}
-	}
-
-	pub fn morden() -> NetworkParams {
-		NetworkParams {
-			maximum_extra_data_size: U256::from(32u64),
-			min_gas_limit: U256::from(5000u64),
-			gas_floor_target: U256::from(3_141_592u64),
-			gas_limit_bounds_divisor: U256::from(1024u64),
-			minimum_difficulty: U256::from(131_072u64),
-			difficulty_bound_divisor: U256::from(2048u64),
-			duration_limit: U256::from(13u64),
-			block_reward: ether() * U256::from(5u64),
-			account_start_nonce: U256::from(1u64) << 20
-		}
-	}
-
-	pub fn maximum_extra_data_size(&self) -> U256 { self.maximum_extra_data_size }
-	pub fn min_gas_limit(&self) -> U256 { self.min_gas_limit }
-	pub fn gas_limit_bounds_divisor(&self) -> U256 { self.gas_limit_bounds_divisor }
-	pub fn minimum_difficulty(&self) -> U256 { self.minimum_difficulty }
-	pub fn difficulty_bound_divisor(&self) -> U256 { self.difficulty_bound_divisor }
-	pub fn duration_limit(&self) -> U256 { self.duration_limit }
-	pub fn block_reward(&self) -> U256 { self.block_reward }
-	pub fn gas_floor_target(&self) -> U256 { self.gas_floor_target }
-	pub fn account_start_nonce(&self) -> U256 { self.account_start_nonce }
-}
-
--- a/src/null_engine.rs
+++ b/src/null_engine.rs
@ -0,0 +1,21 @@
+use engine::Engine;
+use spec::Spec;
+use evm_schedule::EvmSchedule;
+use env_info::EnvInfo;
+
+/// An engine which does not provide any consensus mechanism.
+pub struct NullEngine {
+	spec: Spec,
+}
+
+impl NullEngine {
+	pub fn new_boxed(spec: Spec) -> Box<Engine> {
+		Box::new(NullEngine{spec: spec})
+	}
+}
+
+impl Engine for NullEngine {
+	fn name(&self) -> &str { "NullEngine" }
+	fn spec(&self) -> &Spec { &self.spec }
+	fn evm_schedule(&self, _env_info: &EnvInfo) -> EvmSchedule { EvmSchedule::new_frontier() }
+}
--- a/src/receipt.rs
+++ b/src/receipt.rs
@ -0,0 +1,7 @@
+use util::hash::*;
+
+/// Information describing execution of a transaction.
+pub struct Receipt {
+	// TODO
+	pub state_root: H256,
+}
--- a/src/spec.rs
+++ b/src/spec.rs
@ -0,0 +1,189 @@
+use std::collections::hash_map::*;
+use std::cell::*;
+use std::str::FromStr;
+use util::uint::*;
+use util::hash::*;
+use util::bytes::*;
+use util::triehash::*;
+use util::error::*;
+use util::rlp::*;
+use account::Account;
+use engine::Engine;
+use builtin::Builtin;
+use null_engine::NullEngine;
+use denominations::*;
+
+/// Parameters for a block chain; includes both those intrinsic to the design of the
+/// chain and those to be interpreted by the active chain engine.
+pub struct Spec {
+	// What engine are we using for this?
+	pub engine_name: String,
+
+	// Various parameters for the chain operation.
+	pub block_reward: U256,
+	pub maximum_extra_data_size: U256,
+	pub account_start_nonce: U256,
+	pub misc: HashMap<String, Bytes>,
+
+	// Builtin-contracts are here for now but would like to abstract into Engine API eventually.
+	pub builtins: HashMap<Address, Builtin>,
+
+	// Genesis params.
+	pub parent_hash: H256,
+	pub author: Address,
+	pub difficulty: U256,
+	pub gas_limit: U256,
+	pub gas_used: U256,
+	pub timestamp: U256,
+	pub extra_data: Bytes,
+	pub genesis_state: HashMap<Address, Account>,
+	pub seal_fields: usize,
+	pub seal_rlp: Bytes,
+
+	// May be prepopulated if we know this in advance.
+	state_root_memo: RefCell<Option<H256>>,
+}
+
+impl Spec {
+	/// Convert this object into a boxed Engine of the right underlying type.
+	// TODO avoid this hard-coded nastiness - use dynamic-linked plugin framework instead.
+	pub fn to_engine(self) -> Result<Box<Engine>, EthcoreError> {
+		match self.engine_name.as_ref() {
+			"NullEngine" => Ok(NullEngine::new_boxed(self)),
+			_ => Err(EthcoreError::UnknownName)
+		}
+	}
+
+	/// Return the state root for the genesis state, memoising accordingly. 
+	pub fn state_root(&self) -> Ref<H256> {
+		if self.state_root_memo.borrow().is_none() {
+			*self.state_root_memo.borrow_mut() = Some(trie_root(self.genesis_state.iter().map(|(k, v)| (k.to_vec(), v.rlp())).collect()));
+		}
+		Ref::map(self.state_root_memo.borrow(), |x|x.as_ref().unwrap())
+	}
+
+	pub fn block_reward(&self) -> U256 { self.block_reward }
+	pub fn maximum_extra_data_size(&self) -> U256 { self.maximum_extra_data_size }
+	pub fn account_start_nonce(&self) -> U256 { self.account_start_nonce }
+
+	/// Compose the genesis block for this chain.
+	pub fn genesis_block(&self) -> Bytes {
+		// TODO
+		unimplemented!();
+	}
+}
+
+
+impl Spec {
+	pub fn olympic() -> Spec {
+		Spec {
+			engine_name: "Ethash".to_string(),
+			block_reward: finney() * U256::from(1500u64),
+			maximum_extra_data_size: U256::from(1024u64),
+			account_start_nonce: U256::from(0u64),
+			misc: vec![
+				("gas_limit_bounds_divisor", encode(&1024u64)), 
+				("minimum_difficulty", encode(&131_072u64)), 
+				("difficulty_bound_divisor", encode(&2048u64)), 
+				("duration_limit", encode(&8u64)), 
+				("min_gas_limit", encode(&125_000u64)), 
+				("gas_floor_target", encode(&3_141_592u64)), 
+			].into_iter().fold(HashMap::new(), | mut acc, vec | {
+				acc.insert(vec.0.to_string(), vec.1);
+				acc
+			}),
+			builtins: HashMap::new(),			// TODO: make correct
+			parent_hash: H256::new(),
+			author: Address::new(),
+			difficulty: U256::from(131_072u64),
+			gas_limit: U256::from(0u64),
+			gas_used: U256::from(0u64),
+			timestamp: U256::from(0u64),
+			extra_data: vec![],
+			genesis_state: vec![				// TODO: make correct
+				(Address::new(), Account::new_basic(U256::from(1) << 200, U256::from(0)))
+			].into_iter().fold(HashMap::new(), | mut acc, vec | {
+				acc.insert(vec.0, vec.1);
+				acc
+			}),
+			seal_fields: 2,
+			seal_rlp: { let mut r = RlpStream::new_list(2); r.append(&0x2au64); r.append(&H256::new()); r.out() },	// TODO: make correct
+			state_root_memo: RefCell::new(None),
+		}
+	}
+
+	pub fn frontier() -> Spec {
+		Spec {
+			engine_name: "Ethash".to_string(),
+			block_reward: ether() * U256::from(5u64),
+			maximum_extra_data_size: U256::from(32u64),
+			account_start_nonce: U256::from(0u64),
+			misc: vec![
+				("gas_limit_bounds_divisor", encode(&1024u64)), 
+				("minimum_difficulty", encode(&131_072u64)), 
+				("difficulty_bound_divisor", encode(&2048u64)), 
+				("duration_limit", encode(&13u64)), 
+				("min_gas_limit", encode(&5000u64)), 
+				("gas_floor_target", encode(&3_141_592u64)), 
+			].into_iter().fold(HashMap::new(), | mut acc, vec | {
+				acc.insert(vec.0.to_string(), vec.1);
+				acc
+			}),
+			builtins: HashMap::new(),			// TODO: make correct
+			parent_hash: H256::new(),
+			author: Address::new(),
+			difficulty: U256::from(131_072u64),
+			gas_limit: U256::from(0u64),
+			gas_used: U256::from(0u64),
+			timestamp: U256::from(0u64),
+			extra_data: vec![],
+			genesis_state: vec![				// TODO: make correct
+				(Address::new(), Account::new_basic(U256::from(1) << 200, U256::from(0)))
+			].into_iter().fold(HashMap::new(), | mut acc, vec | {
+				acc.insert(vec.0, vec.1);
+				acc
+			}),
+			seal_fields: 2,
+			seal_rlp: { let mut r = RlpStream::new_list(2); r.append(&0x42u64); r.append(&H256::new()); r.out() },
+			state_root_memo: RefCell::new(None),
+		}
+	}
+
+	pub fn morden() -> Spec {
+		Spec {
+			engine_name: "Ethash".to_string(),
+			block_reward: ether() * U256::from(5u64),
+			maximum_extra_data_size: U256::from(32u64),
+			account_start_nonce: U256::from(1u64) << 20,
+			misc: vec![
+				("gas_limit_bounds_divisor", encode(&1024u64)), 
+				("minimum_difficulty", encode(&131_072u64)), 
+				("difficulty_bound_divisor", encode(&2048u64)), 
+				("duration_limit", encode(&13u64)), 
+				("min_gas_limit", encode(&5000u64)), 
+				("gas_floor_target", encode(&3_141_592u64)), 
+			].into_iter().fold(HashMap::new(), | mut acc, vec | {
+				acc.insert(vec.0.to_string(), vec.1);
+				acc
+			}),
+			builtins: HashMap::new(),			// TODO: make correct
+			parent_hash: H256::new(),
+			author: Address::new(),
+			difficulty: U256::from(131_072u64),
+			gas_limit: U256::from(0u64),
+			gas_used: U256::from(0u64),
+			timestamp: U256::from(0u64),
+			extra_data: vec![],
+			genesis_state: vec![				// TODO: make correct
+				(Address::new(), Account::new_basic(U256::from(1) << 200, U256::from(0)))
+			].into_iter().fold(HashMap::new(), | mut acc, vec | {
+				acc.insert(vec.0, vec.1);
+				acc
+			}),
+			seal_fields: 2,
+			seal_rlp: { let mut r = RlpStream::new_list(2); r.append(&0x00006d6f7264656eu64); r.append(&H256::from_str("00000000000000000000000000000000000000647572616c65787365646c6578").unwrap()); r.out() },	// TODO: make correct
+			state_root_memo: RefCell::new(None),
+		}
+	}
+}
+
--- a/src/state.rs
+++ b/src/state.rs
@ -1,19 +1,29 @@
+use std::cell::*;
+use std::ops::*;
 use std::collections::HashMap;
 use util::hash::*;
 use util::hashdb::*;
 use util::overlaydb::*;
 use util::trie::*;
+use util::bytes::*;
 use util::rlp::*;
 use util::uint::*;
 use account::Account;
+use transaction::Transaction;
+use receipt::Receipt;
+use env_info::EnvInfo;
+use engine::Engine;
+
+/// Information concerning the result of the `State::apply` operation.
+pub struct ApplyResult;	// TODO

 /// Representation of the entire state of all accounts in the system.
 pub struct State {
 	db: OverlayDB,
 	root: H256,
-	cache: HashMap<Address, Option<Account>>,
+	cache: RefCell<HashMap<Address, Option<Account>>>,

-	_account_start_nonce: U256,
+	account_start_nonce: U256,
 }

 impl State {
@ -22,14 +32,14 @@ impl State {
 		let mut root = H256::new();
 		{
 			// init trie and reset root too null
-			let _ = TrieDB::new(&mut db, &mut root);
+			let _ = TrieDBMut::new(&mut db, &mut root);
 		}

 		State {
 			db: db,
 			root: root,
-			cache: HashMap::new(),
-			_account_start_nonce: account_start_nonce,
+			cache: RefCell::new(HashMap::new()),
+			account_start_nonce: account_start_nonce,
 		}
 	}

@ -37,14 +47,14 @@ impl State {
 	pub fn new_existing(mut db: OverlayDB, mut root: H256, account_start_nonce: U256) -> State {
 		{
 			// trie should panic! if root does not exist
-			let _ = TrieDB::new_existing(&mut db, &mut root);
+			let _ = TrieDB::new(&mut db, &mut root);
 		}

 		State {
 			db: db,
 			root: root,
-			cache: HashMap::new(),
-			_account_start_nonce: account_start_nonce,
+			cache: RefCell::new(HashMap::new()),
+			account_start_nonce: account_start_nonce,
 		}
 	}

@ -53,6 +63,11 @@ impl State {
 		Self::new(OverlayDB::new_temp(), U256::from(0u8))
 	}

+	/// Destroy the current object and return root and database.
+	pub fn drop(self) -> (H256, OverlayDB) {
+		(self.root, self.db)
+	}
+
 	/// Return reference to root
 	pub fn root(&self) -> &H256 {
 		&self.root
@ -63,7 +78,69 @@ impl State {
 		&mut self.db
 	}

-	/// Commit accounts to TrieDB. This is similar to cpp-ethereum's dev::eth::commit.
+	/// Get the balance of account `a`.
+	pub fn balance(&self, a: &Address) -> U256 {
+		self.get(a, false).as_ref().map(|account| account.balance().clone()).unwrap_or(U256::from(0u8))
+	}
+
+	/// Get the nonce of account `a`.
+	pub fn nonce(&self, a: &Address) -> U256 {
+		self.get(a, false).as_ref().map(|account| account.nonce().clone()).unwrap_or(U256::from(0u8))
+	}
+
+	/// Mutate storage of account `a` so that it is `value` for `key`.
+	pub fn storage_at(&self, a: &Address, key: &H256) -> H256 {
+		self.get(a, false).as_ref().map(|a|a.storage_at(&self.db, key)).unwrap_or(H256::new())	
+	}
+
+	/// Mutate storage of account `a` so that it is `value` for `key`.
+	pub fn code(&self, a: &Address) -> Option<Vec<u8>> {
+		self.get(a, true).as_ref().map(|a|a.code().map(|x|x.to_vec())).unwrap_or(None)
+	}
+
+	/// Add `incr` to the balance of account `a`.
+	pub fn add_balance(&mut self, a: &Address, incr: &U256) {
+		self.require(a, false).add_balance(incr)
+	}
+
+	/// Subtract `decr` from the balance of account `a`.
+	pub fn sub_balance(&mut self, a: &Address, decr: &U256) {
+		self.require(a, false).sub_balance(decr)
+	}
+
+	/// Subtracts `by` from the balance of `from` and adds it to that of `to`.
+	pub fn transfer_balance(&mut self, from: &Address, to: &Address, by: &U256) {
+		self.sub_balance(from, by);
+		self.add_balance(to, by);
+	}
+
+	/// Increment the nonce of account `a` by 1.
+	pub fn inc_nonce(&mut self, a: &Address) {
+		self.require(a, false).inc_nonce()
+	}
+
+	/// Mutate storage of account `a` so that it is `value` for `key`.
+	pub fn set_storage(&mut self, a: &Address, key: H256, value: H256) {
+		self.require(a, false).set_storage(key, value);
+	}
+
+	/// Mutate storage of account `a` so that it is `value` for `key`.
+	pub fn set_code(&mut self, a: &Address, code: Bytes) {
+		self.require_or_from(a, true, || Account::new_contract(U256::from(0u8))).set_code(code);
+	}
+
+	/// Execute a given transaction.
+	/// This will change the state accordingly.
+	pub fn apply(_env_info: &EnvInfo, _engine: &Engine, _t: &Transaction, _is_permanent: bool) -> (ApplyResult, Receipt) {
+		unimplemented!();
+	}
+
+	/// Convert into a JSON representation.
+	pub fn as_json(&self) -> String {
+		unimplemented!();
+	}
+
+	/// Commit accounts to TrieDBMut. This is similar to cpp-ethereum's dev::eth::commit.
 	/// `accounts` is mutable because we may need to commit the code or storage and record that.
 	pub fn commit_into(db: &mut HashDB, mut root: H256, accounts: &mut HashMap<Address, Option<Account>>) -> H256 {
 		// first, commit the sub trees.
@ -79,7 +156,7 @@ impl State {
 		}

 		{
-			let mut trie = TrieDB::new_existing(db, &mut root);
+			let mut trie = TrieDBMut::new_existing(db, &mut root);
 			for (address, ref a) in accounts.iter() {
 				match a {
 					&&Some(ref account) => trie.insert(address, &account.rlp()),
@ -93,28 +170,49 @@ impl State {
 	/// Commits our cached account changes into the trie.
 	pub fn commit(&mut self) {
 		let r = self.root.clone();	// would prefer not to do this, really. 
-		self.root = Self::commit_into(&mut self.db, r, &mut self.cache);
+		self.root = Self::commit_into(&mut self.db, r, self.cache.borrow_mut().deref_mut());
+	}
+
+	/// Populate the state from `accounts`. Just uses `commit_into`.
+	pub fn populate_from(&mut self, _accounts: &mut HashMap<Address, Option<Account>>) {
+		unimplemented!();
+	}
+
+	/// Pull account `a` in our cache from the trie DB and return it.
+	/// `require_code` requires that the code be cached, too.
+	fn get(&self, a: &Address, require_code: bool) -> Ref<Option<Account>> {
+		self.cache.borrow_mut().entry(a.clone()).or_insert_with(||
+			TrieDB::new(&self.db, &self.root).get(&a).map(|rlp| Account::from_rlp(rlp)));
+		if require_code {
+			if let Some(ref mut account) = self.cache.borrow_mut().get_mut(a).unwrap().as_mut() {
+				account.cache_code(&self.db);
+			}
+		}
+		Ref::map(self.cache.borrow(), |m| m.get(a).unwrap())
 	}

 	/// Pull account `a` in our cache from the trie DB. `require_code` requires that the code be cached, too.
 	/// `force_create` creates a new, empty basic account if there is not currently an active account.
-	fn ensure_cached(&mut self, a: &Address, require_code: bool, force_create: bool) {
-		if self.cache.get(a).is_none() {
-			// load from trie.
-			self.cache.insert(a.clone(), TrieDB::new(&mut self.db, &mut self.root).at(&a).map(|rlp| Account::from_rlp(rlp)));
+	fn require(&self, a: &Address, require_code: bool) -> RefMut<Account> {
+		self.require_or_from(a, require_code, || Account::new_basic(U256::from(0u8), self.account_start_nonce))
+	}
+
+	/// Pull account `a` in our cache from the trie DB. `require_code` requires that the code be cached, too.
+	/// `force_create` creates a new, empty basic account if there is not currently an active account.
+	fn require_or_from<F: FnOnce() -> Account>(&self, a: &Address, require_code: bool, default: F) -> RefMut<Account> {
+		self.cache.borrow_mut().entry(a.clone()).or_insert_with(||
+			TrieDB::new(&self.db, &self.root).get(&a).map(|rlp| Account::from_rlp(rlp)));
+		if self.cache.borrow().get(a).unwrap().is_none() {
+			self.cache.borrow_mut().insert(a.clone(), Some(default()));
 		}

-		if self.cache.get(a).unwrap().is_none() {
-			if !force_create { return; }
-			// create a new account
-			self.cache.insert(a.clone(), Some(Account::new_basic(U256::from(0u8))));
-		}
-
-		if require_code {
-			if let &mut Some(ref mut account) = self.cache.get_mut(a).unwrap() {
-				account.ensure_cached(&self.db);
+		let b = self.cache.borrow_mut();
+		RefMut::map(b, |m| m.get_mut(a).unwrap().as_mut().map(|account| {
+			if require_code {
+				account.cache_code(&self.db);
 			}
-		}
+			account
+		}).unwrap())
 	}
 }

@ -125,17 +223,111 @@ use super::*;
 use util::hash::*;
 use util::trie::*;
 use util::rlp::*;
+use util::uint::*;
 use std::str::FromStr;
+use account::*;

 #[test]
-fn playpen() {
+fn code_from_database() {
+	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
+	let (r, db) = {
+		let mut s = State::new_temp();
+		s.require_or_from(&a, false, ||Account::new_contract(U256::from(42u32)));
+		s.set_code(&a, vec![1, 2, 3]);
+		assert_eq!(s.code(&a), Some([1u8, 2, 3].to_vec()));
+		s.commit();
+		assert_eq!(s.code(&a), Some([1u8, 2, 3].to_vec()));
+		s.drop()
+	};
+
+	let s = State::new_existing(db, r, U256::from(0u8));
+	assert_eq!(s.code(&a), Some([1u8, 2, 3].to_vec()));
+}
+
+#[test]
+fn storage_at_from_database() {
+	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
+	let (r, db) = {
+		let mut s = State::new_temp();
+		s.set_storage(&a, H256::from(&U256::from(01u64)), H256::from(&U256::from(69u64)));
+		s.commit();
+		s.drop()
+	};
+
+	let s = State::new_existing(db, r, U256::from(0u8));
+	assert_eq!(s.storage_at(&a, &H256::from(&U256::from(01u64))), H256::from(&U256::from(69u64)));
+}
+
+#[test]
+fn get_from_database() {
+	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
+	let (r, db) = {
+		let mut s = State::new_temp();
+		s.inc_nonce(&a);
+		s.add_balance(&a, &U256::from(69u64));
+		s.commit();
+		assert_eq!(s.balance(&a), U256::from(69u64));
+		s.drop()
+	};
+
+	let s = State::new_existing(db, r, U256::from(0u8));
+	assert_eq!(s.balance(&a), U256::from(69u64));
+	assert_eq!(s.nonce(&a), U256::from(1u64));
+}
+
+#[test]
+fn alter_balance() {
+	let mut s = State::new_temp();
+	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
+	let b = Address::from_str("0000000000000000000000000000000000000001").unwrap();
+	s.add_balance(&a, &U256::from(69u64));
+	assert_eq!(s.balance(&a), U256::from(69u64));
+	s.commit();
+	assert_eq!(s.balance(&a), U256::from(69u64));
+	s.sub_balance(&a, &U256::from(42u64));
+	assert_eq!(s.balance(&a), U256::from(27u64));
+	s.commit();
+	assert_eq!(s.balance(&a), U256::from(27u64));
+	s.transfer_balance(&a, &b, &U256::from(18u64));
+	assert_eq!(s.balance(&a), U256::from(9u64));
+	assert_eq!(s.balance(&b), U256::from(18u64));
+	s.commit();
+	assert_eq!(s.balance(&a), U256::from(9u64));
+	assert_eq!(s.balance(&b), U256::from(18u64));
+}
+
+#[test]
+fn alter_nonce() {
+	let mut s = State::new_temp();
+	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
+	s.inc_nonce(&a);
+	assert_eq!(s.nonce(&a), U256::from(1u64));
+	s.inc_nonce(&a);
+	assert_eq!(s.nonce(&a), U256::from(2u64));
+	s.commit();
+	assert_eq!(s.nonce(&a), U256::from(2u64));
+	s.inc_nonce(&a);
+	assert_eq!(s.nonce(&a), U256::from(3u64));
+	s.commit();
+	assert_eq!(s.nonce(&a), U256::from(3u64));
+}
+
+#[test]
+fn balance_nonce() {
+	let mut s = State::new_temp();
+	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
+	assert_eq!(s.balance(&a), U256::from(0u64));
+	assert_eq!(s.nonce(&a), U256::from(0u64));
+	s.commit();
+	assert_eq!(s.balance(&a), U256::from(0u64));
+	assert_eq!(s.nonce(&a), U256::from(0u64));
 }

 #[test]
 fn ensure_cached() {
 	let mut s = State::new_temp();
 	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
-	s.ensure_cached(&a, false, true);
+	s.require(&a, false);
 	s.commit();
 	assert_eq!(s.root().hex(), "ec68b85fa2e0526dc0e821a5b33135459114f19173ce0479f5c09b21cc25b9a4");
 }
--- a/src/transaction.rs
+++ b/src/transaction.rs
@ -3,20 +3,23 @@ use util::bytes::*;
 use util::uint::*;
 use util::rlp::*;

+/// A set of information describing an externally-originating message call
+/// or contract creation operation.
 pub struct Transaction {
 	nonce: U256,
 	gas_price: U256,
 	gas: U256,
-	receive_address: Option<Address>,
+	to: Option<Address>,
 	value: U256,
 	data: Bytes,
 }

 impl Transaction {
+	/// Is this transaction meant to create a contract?
 	pub fn is_contract_creation(&self) -> bool {
-		self.receive_address.is_none()
+		self.to.is_none()
 	}
-
+	/// Is this transaction meant to send a message?
 	pub fn is_message_call(&self) -> bool {
 		!self.is_contract_creation()
 	}
@ -28,7 +31,7 @@ impl Encodable for Transaction {
 			self.nonce.encode(e);
 			self.gas_price.encode(e);
 			self.gas.encode(e);
-			self.receive_address.encode(e);
+			self.to.encode(e);
 			self.value.encode(e);
 			self.data.encode(e);
 		})
@ -36,14 +39,14 @@ impl Encodable for Transaction {
 }

 impl Decodable for Transaction {
-	fn decode<D>(decoder: &D) -> Result<Self, DecoderError>  where D: Decoder {
+	fn decode<D>(decoder: &D) -> Result<Self, DecoderError> where D: Decoder {
 		let d = try!(decoder.as_list());

 		let transaction = Transaction {
 			nonce: try!(Decodable::decode(&d[0])),
 			gas_price: try!(Decodable::decode(&d[1])),
 			gas: try!(Decodable::decode(&d[2])),
-			receive_address: try!(Decodable::decode(&d[3])),
+			to: try!(Decodable::decode(&d[3])),
 			value: try!(Decodable::decode(&d[4])),
 			data: try!(Decodable::decode(&d[5])),
 		};
--- a/src/views.rs
+++ b/src/views.rs
@ -4,7 +4,7 @@ use util::hash::*;
 use util::uint::*;
 use util::rlp::*;
 use util::sha3::*;
-use blockheader::*;
+use header::*;
 use transaction::*;

 /// View onto block rlp.