Merge pull request #38 from gavofyork/state

Minor reworking of Account.

src/account.rs

@@ -6,52 +6,91 @@ use util::trie::*;
 use util::rlp::*;
 use util::uint::*;
 
-enum HashOrData {
-	Hash(H256),
-	Data(Bytes),
-	Both(H256, Bytes),
-}
+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.
 pub struct Account {
+	// Balance of the account.
 	balance: U256,
+	// Nonce of the account.
 	nonce: U256,
 	// Trie-backed storage.
 	storage_root: H256,
 	// Overlay on trie-backed storage.
 	storage_overlay: HashMap<H256, H256>,
-	code: HashOrData,
+	// 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.
+	code_cache: Bytes,
 }
 
 impl Account {
-	pub fn new_with_balance(balance: U256) -> Account {
+	/// General constructor.
+	pub fn new(balance: U256, nonce: U256, storage: HashMap<H256, H256>, code: Bytes) -> Account {
+		Account {
+			balance: balance,
+			nonce: nonce,
+			storage_root: SHA3_NULL_RLP,
+			storage_overlay: storage,
+			code_hash: None,
+			code_cache: code
+		}
+	}
+
+	/// Create a new account with the given balance.
+	pub fn new_basic(balance: U256) -> Account {
 		Account {
 			balance: balance,
 			nonce: U256::from(0u8),
-			code: HashOrData::Data(vec![]),
 			storage_root: SHA3_NULL_RLP,
 			storage_overlay: HashMap::new(),
+			code_hash: Some(SHA3_EMPTY),
+			code_cache: vec![],
 		}
 	}
 
+	/// Create a new contract account.
+	/// NOTE: make sure you use `set_code` on this before `commit`ing.
+	pub fn new_contract(balance: U256) -> Account {
+		Account {
+			balance: balance,
+			nonce: U256::from(0u8),
+			storage_root: SHA3_NULL_RLP,
+			storage_overlay: HashMap::new(),
+			code_hash: None,
+			code_cache: vec![],
+		}
+	}
+
+	/// Create a new account from RLP.
 	pub fn from_rlp(_rlp: &[u8]) -> Account {
-		//TODO
+//		unimplemented!();
 		Account {
 			balance: U256::from(0u8),
 			nonce: U256::from(0u8),
-			code: HashOrData::Hash(SHA3_NULL_RLP),
 			storage_root: SHA3_NULL_RLP,
 			storage_overlay: HashMap::new(),
+			code_hash: Some(SHA3_EMPTY),
+			code_cache: vec![],
 		}
 	}
 
-	pub fn balance(&self) -> &U256 { &self.balance }
-	pub fn nonce(&self) -> &U256 { &self.nonce }
-	pub fn code_hash(&self) -> Option<&H256> {
-		match self.code {
-			HashOrData::Hash(ref h) | HashOrData::Both(ref h, _) => Some(h),
-			_ => None,
-		}
+	/// Set this account's code to the given code.
+	/// NOTE: Account should have been created with `new_contract`.
+	pub fn set_code(&mut self, code: Bytes) {
+		assert!(self.code_hash.is_none());
+		self.code_cache = code;
 	}
+
+	/// return the balance associated with this account.
+	pub fn balance(&self) -> &U256 { &self.balance }
+	/// return the nonce associated with this account.
+	pub fn nonce(&self) -> &U256 { &self.nonce }
+	/// return the code hash associated with this account.
+	pub fn code_hash(&self) -> H256 {
+		self.code_hash.clone().unwrap_or(SHA3_EMPTY)
+	}
+	/// return the storage root associated with this account.
 	pub fn storage_root(&self) -> Option<&H256> { if self.storage_overlay.is_empty() {Some(&self.storage_root)} else {None} }
 
 	/// Commit the `storage_overlay` to the backing DB and update `storage_root`.
@@ -67,19 +106,18 @@ impl Account {
 
 	/// Commit any unsaved code and ensure code is not `HashOrData::Data`.
 	pub fn commit_code(&mut self, db: &mut HashDB) {
-		if let Some(new_code) = match self.code {
-			HashOrData::Data(ref d) => { Some(HashOrData::Both(db.insert(d), d.clone())) },
-			_ => None,
-		}{
-			self.code = new_code;
+		if self.code_hash.is_none() && !self.code_cache.is_empty() {
+			self.code_hash = Some(db.insert(&self.code_cache));
 		}
+	}
 
-		// that nasty bit of code should really be:
-		/*if let HashOrData::Data(ref d) = self.code {
-    		let h = db.insert(d);
-    		self.code = HashOrData::Both(h, d.clone());
-		}*/
-		// a rewrite it closer to this would be good...
-
+	/// Export to RLP.
+	pub fn rlp(&self) -> Bytes {
+		let mut stream = RlpStream::new_list(4);
+		stream.append(&self.nonce);
+		stream.append(&self.balance);
+		stream.append(&self.storage_root);
+		stream.append(self.code_hash.as_ref().expect("Cannot form RLP of contract account without code."));
+		stream.out()
 	}
 }

src/state.rs

@@ -7,10 +7,11 @@ use util::rlp::*;
 use util::uint::*;
 use account::Account;
 
+/// Representation of the entire state of all accounts in the system.
 pub struct State {
 	db: OverlayDB,
 	root: H256,
-	_cache: HashMap<Address, Option<Account>>,
+	cache: HashMap<Address, Option<Account>>,
 
 	_account_start_nonce: U256,
 }
@@ -27,7 +28,7 @@ impl State {
 		State {
 			db: db,
 			root: root,
-			_cache: HashMap::new(),
+			cache: HashMap::new(),
 			_account_start_nonce: account_start_nonce,
 		}
 	}
@@ -42,7 +43,7 @@ impl State {
 		State {
 			db: db,
 			root: root,
-			_cache: HashMap::new(),
+			cache: HashMap::new(),
 			_account_start_nonce: account_start_nonce,
 		}
 	}
@@ -57,37 +58,42 @@ impl State {
 		&self.root
 	}
 
-	/// Commit everything to the disk
-	pub fn commit_db(&mut self) {
-		self.db.commit().expect("Number of kills exceeded number of inserts!");
+	/// Expose the underlying database; good to use for calling `state.db().commit()`.
+	pub fn db(&mut self) -> &mut OverlayDB {
+		&mut self.db
 	}
 
 	/// Commit accounts to TrieDB. This is simplified version of
 	/// cpp-ethereum's dev::eth::commit.
 	/// accounts mutable because we may need to commit the code or storage and record that.
-	pub fn commit(db: &mut HashDB, mut root: H256, accounts: &mut HashMap<Address, Account>) -> H256 {
+	pub fn commit_into(db: &mut HashDB, mut root: H256, accounts: &mut HashMap<Address, Option<Account>>) -> H256 {
 		// first, commit the sub trees.
-		for (_, ref mut account) in accounts.iter_mut() {
-			account.commit_storage(db);
-			account.commit_code(db);
+		// TODO: is this necessary or can we dispense with the `ref mut a` for just `a`?
+		for (_, ref mut a) in accounts.iter_mut() {
+			match a {
+				&mut&mut Some(ref mut account) => {
+					account.commit_storage(db);
+					account.commit_code(db);
+				}
+				&mut&mut None => {}
+			}
 		}
 
 		{
 			let mut trie = TrieDB::new_existing(db, &mut root);
-			for (address, account) in accounts.iter() {
-				let mut stream = RlpStream::new_list(4);
-				stream.append(account.nonce());
-				stream.append(account.balance());
-				stream.append(account.storage_root().unwrap());
-				stream.append(account.code_hash().unwrap());
-				trie.insert(address, &stream.out());
+			for (address, ref a) in accounts.iter() {
+				match a {
+					&&Some(ref account) => trie.insert(address, &account.rlp()),
+					&&None => trie.remove(address),
+				}
 			}
 		}
 		root
 	}
 
-	pub fn insert_accounts(&mut self, accounts: &mut HashMap<Address, Account>) {
+	/// 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(&mut self.db, r, accounts);
+		self.root = Self::commit_into(&mut self.db, r, &mut self.cache);
 	}
 }