JournalDB -> Box<JournalDB>, and it's a trait.

ethcore/src/block.rs

@@ -171,7 +171,7 @@ pub struct SealedBlock {
 
 impl<'x> OpenBlock<'x> {
 	/// Create a new OpenBlock ready for transaction pushing.
-	pub fn new(engine: &'x Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes, author: Address, extra_data: Bytes) -> Self {
+	pub fn new(engine: &'x Engine, db: Box<JournalDB + Send>, parent: &Header, last_hashes: LastHashes, author: Address, extra_data: Bytes) -> Self {
 		let mut r = OpenBlock {
 			block: ExecutedBlock::new(State::from_existing(db, parent.state_root().clone(), engine.account_start_nonce())),
 			engine: engine,
@@ -317,7 +317,7 @@ impl ClosedBlock {
 	}
 
 	/// Drop this object and return the underlieing database.
-	pub fn drain(self) -> JournalDB { self.block.state.drop().1 }
+	pub fn drain(self) -> Box<JournalDB + Send> { self.block.state.drop().1 }
 }
 
 impl SealedBlock {
@@ -331,7 +331,7 @@ impl SealedBlock {
 	}
 
 	/// Drop this object and return the underlieing database.
-	pub fn drain(self) -> JournalDB { self.block.state.drop().1 }
+	pub fn drain(self) -> Box<JournalDB + Send> { self.block.state.drop().1 }
 }
 
 impl IsBlock for SealedBlock {
@@ -339,10 +339,10 @@ impl IsBlock for SealedBlock {
 }
 
 /// Enact the block given by block header, transactions and uncles
-pub fn enact(header: &Header, transactions: &[SignedTransaction], uncles: &[Header], engine: &Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock, Error> {
+pub fn enact(header: &Header, transactions: &[SignedTransaction], uncles: &[Header], engine: &Engine, db: Box<JournalDB + Send>, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock, Error> {
 	{
 		if ::log::max_log_level() >= ::log::LogLevel::Trace {
-			let s = State::from_existing(db.clone(), parent.state_root().clone(), engine.account_start_nonce());
+			let s = State::from_existing(db.spawn(), parent.state_root().clone(), engine.account_start_nonce());
 			trace!("enact(): root={}, author={}, author_balance={}\n", s.root(), header.author(), s.balance(&header.author()));
 		}
 	}
@@ -357,20 +357,20 @@ pub fn enact(header: &Header, transactions: &[SignedTransaction], uncles: &[Head
 }
 
 /// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header
-pub fn enact_bytes(block_bytes: &[u8], engine: &Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock, Error> {
+pub fn enact_bytes(block_bytes: &[u8], engine: &Engine, db: Box<JournalDB + Send>, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock, Error> {
 	let block = BlockView::new(block_bytes);
 	let header = block.header();
 	enact(&header, &block.transactions(), &block.uncles(), engine, db, parent, last_hashes)
 }
 
 /// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header
-pub fn enact_verified(block: &PreverifiedBlock, engine: &Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock, Error> {
+pub fn enact_verified(block: &PreverifiedBlock, engine: &Engine, db: Box<JournalDB + Send>, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock, Error> {
 	let view = BlockView::new(&block.bytes);
 	enact(&block.header, &block.transactions, &view.uncles(), engine, db, parent, last_hashes)
 }
 
 /// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header. Seal the block aferwards
-pub fn enact_and_seal(block_bytes: &[u8], engine: &Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<SealedBlock, Error> {
+pub fn enact_and_seal(block_bytes: &[u8], engine: &Engine, db: Box<JournalDB + Send>, parent: &Header, last_hashes: LastHashes) -> Result<SealedBlock, Error> {
 	let header = BlockView::new(block_bytes).header_view();
 	Ok(try!(try!(enact_bytes(block_bytes, engine, db, parent, last_hashes)).seal(engine, header.seal())))
 }

ethcore/src/client.rs

@@ -214,7 +214,7 @@ impl ClientReport {
 pub struct Client<V = CanonVerifier> where V: Verifier {
 	chain: Arc<RwLock<BlockChain>>,
 	engine: Arc<Box<Engine>>,
-	state_db: Mutex<JournalDB>,
+	state_db: Mutex<Box<JournalDB + Send>>,
 	block_queue: RwLock<BlockQueue>,
 	report: RwLock<ClientReport>,
 	import_lock: Mutex<()>,
@@ -253,8 +253,8 @@ impl<V> Client<V> where V: Verifier {
 		state_path.push("state");
 
 		let engine = Arc::new(try!(spec.to_engine()));
-		let mut state_db = JournalDB::from_prefs(state_path.to_str().unwrap(), config.prefer_journal);
+		let mut state_db = Box::new(OptionOneDB::from_prefs(state_path.to_str().unwrap(), config.prefer_journal));
-		if state_db.is_empty() && engine.spec().ensure_db_good(&mut state_db) {
+		if state_db.is_empty() && engine.spec().ensure_db_good(state_db.deref_mut()) {
 			state_db.commit(0, &engine.spec().genesis_header().hash(), None).expect("Error commiting genesis state to state DB");
 		}
 
@@ -336,7 +336,7 @@ impl<V> Client<V> where V: Verifier {
 		// Enact Verified Block
 		let parent = chain_has_parent.unwrap();
 		let last_hashes = self.build_last_hashes(header.parent_hash.clone());
-		let db = self.state_db.lock().unwrap().clone();
+		let db = self.state_db.lock().unwrap().spawn();
 
 		let enact_result = enact_verified(&block, engine, db, &parent, last_hashes);
 		if let Err(e) = enact_result {
@@ -438,7 +438,7 @@ impl<V> Client<V> where V: Verifier {
 
 	/// Get a copy of the best block's state.
 	pub fn state(&self) -> State {
-		State::from_existing(self.state_db.lock().unwrap().clone(), HeaderView::new(&self.best_block_header()).state_root(), self.engine.account_start_nonce())
+		State::from_existing(self.state_db.lock().unwrap().spawn(), HeaderView::new(&self.best_block_header()).state_root(), self.engine.account_start_nonce())
 	}
 
 	/// Get info on the cache.
@@ -507,7 +507,7 @@ impl<V> Client<V> where V: Verifier {
 		let h = self.chain.read().unwrap().best_block_hash();
 		let mut b = OpenBlock::new(
 			self.engine.deref().deref(),
-			self.state_db.lock().unwrap().clone(),
+			self.state_db.lock().unwrap().spawn(),
 			match self.chain.read().unwrap().block_header(&h) { Some(ref x) => x, None => {return;} },
 			self.build_last_hashes(h.clone()),
 			self.author(),

ethcore/src/state.rs

@@ -31,7 +31,7 @@ pub type ApplyResult = Result<Receipt, Error>;
 
 /// Representation of the entire state of all accounts in the system.
 pub struct State {
-	db: JournalDB,
+	db: Box<JournalDB + Send>,
 	root: H256,
 	cache: RefCell<HashMap<Address, Option<Account>>>,
 	snapshots: RefCell<Vec<HashMap<Address, Option<Option<Account>>>>>,
@@ -41,11 +41,11 @@ pub struct State {
 impl State {
 	/// Creates new state with empty state root
 	#[cfg(test)]
-	pub fn new(mut db: JournalDB, account_start_nonce: U256) -> State {
+	pub fn new(mut db: Box<JournalDB + Send>, account_start_nonce: U256) -> State {
 		let mut root = H256::new();
 		{
 			// init trie and reset root too null
-			let _ = SecTrieDBMut::new(&mut db, &mut root);
+			let _ = SecTrieDBMut::new(db.deref_mut(), &mut root);
 		}
 
 		State {
@@ -58,10 +58,10 @@ impl State {
 	}
 
 	/// Creates new state with existing state root
-	pub fn from_existing(db: JournalDB, root: H256, account_start_nonce: U256) -> State {
+	pub fn from_existing(db: Box<JournalDB + Send>, root: H256, account_start_nonce: U256) -> State {
 		{
 			// trie should panic! if root does not exist
-			let _ = SecTrieDB::new(&db, &root);
+			let _ = SecTrieDB::new(db.as_hashdb(), &root);
 		}
 
 		State {
@@ -126,7 +126,7 @@ impl State {
 	}
 
 	/// Destroy the current object and return root and database.
-	pub fn drop(self) -> (H256, JournalDB) {
+	pub fn drop(self) -> (H256, Box<JournalDB + Send>) {
 		(self.root, self.db)
 	}
 
@@ -148,7 +148,7 @@ impl State {
 
 	/// Determine whether an account exists.
 	pub fn exists(&self, a: &Address) -> bool {
-		self.cache.borrow().get(&a).unwrap_or(&None).is_some() || SecTrieDB::new(&self.db, &self.root).contains(&a)
+		self.cache.borrow().get(&a).unwrap_or(&None).is_some() || SecTrieDB::new(self.db.as_hashdb(), &self.root).contains(&a)
 	}
 
 	/// Get the balance of account `a`.
@@ -163,7 +163,7 @@ impl State {
 
 	/// Mutate storage of account `address` so that it is `value` for `key`.
 	pub fn storage_at(&self, address: &Address, key: &H256) -> H256 {
-		self.get(address, false).as_ref().map_or(H256::new(), |a|a.storage_at(&AccountDB::new(&self.db, address), key))
+		self.get(address, false).as_ref().map_or(H256::new(), |a|a.storage_at(&AccountDB::new(self.db.as_hashdb(), address), key))
 	}
 
 	/// Mutate storage of account `a` so that it is `value` for `key`.
@@ -253,7 +253,7 @@ impl State {
 	/// Commits our cached account changes into the trie.
 	pub fn commit(&mut self) {
 		assert!(self.snapshots.borrow().is_empty());
-		Self::commit_into(&mut self.db, &mut self.root, self.cache.borrow_mut().deref_mut());
+		Self::commit_into(self.db.as_hashdb_mut(), &mut self.root, self.cache.borrow_mut().deref_mut());
 	}
 
 	#[cfg(test)]
@@ -285,11 +285,11 @@ impl State {
 	fn get<'a>(&'a self, a: &Address, require_code: bool) -> &'a Option<Account> {
 		let have_key = self.cache.borrow().contains_key(a);
 		if !have_key {
-			self.insert_cache(a, SecTrieDB::new(&self.db, &self.root).get(&a).map(Account::from_rlp))
+			self.insert_cache(a, SecTrieDB::new(self.db.as_hashdb(), &self.root).get(&a).map(Account::from_rlp))
 		}
 		if require_code {
 			if let Some(ref mut account) = self.cache.borrow_mut().get_mut(a).unwrap().as_mut() {
-				account.cache_code(&AccountDB::new(&self.db, a));
+				account.cache_code(&AccountDB::new(self.db.as_hashdb(), a));
 			}
 		}
 		unsafe { ::std::mem::transmute(self.cache.borrow().get(a).unwrap()) }
@@ -305,7 +305,7 @@ impl State {
 	fn require_or_from<'a, F: FnOnce() -> Account, G: FnOnce(&mut Account)>(&self, a: &Address, require_code: bool, default: F, not_default: G) -> &'a mut Account {
 		let have_key = self.cache.borrow().contains_key(a);
 		if !have_key {
-			self.insert_cache(a, SecTrieDB::new(&self.db, &self.root).get(&a).map(Account::from_rlp))
+			self.insert_cache(a, SecTrieDB::new(self.db.as_hashdb(), &self.root).get(&a).map(Account::from_rlp))
 		} else {
 			self.note_cache(a);
 		}
@@ -318,7 +318,7 @@ impl State {
 
 		unsafe { ::std::mem::transmute(self.cache.borrow_mut().get_mut(a).unwrap().as_mut().map(|account| {
 			if require_code {
-				account.cache_code(&AccountDB::new(&self.db, a));
+				account.cache_code(&AccountDB::new(self.db.as_hashdb(), a));
 			}
 			account
 		}).unwrap()) }

ethcore/src/tests/helpers.rs

@@ -250,9 +250,9 @@ pub fn generate_dummy_empty_blockchain() -> GuardedTempResult<BlockChain> {
 	}
 }
 
-pub fn get_temp_journal_db() -> GuardedTempResult<JournalDB> {
+pub fn get_temp_journal_db() -> GuardedTempResult<Box<JournalDB + Send>> {
 	let temp = RandomTempPath::new();
-	let journal_db = JournalDB::new(temp.as_str());
+	let journal_db = Box::new(OptionOneDB::new(temp.as_str()));
 	GuardedTempResult {
 		_temp: temp,
 		result: Some(journal_db)
@@ -268,8 +268,8 @@ pub fn get_temp_state() -> GuardedTempResult<State> {
 	}
 }
 
-pub fn get_temp_journal_db_in(path: &Path) -> JournalDB {
+pub fn get_temp_journal_db_in(path: &Path) -> Box<JournalDB + Send> {
-	JournalDB::new(path.to_str().unwrap())
+	Box::new(OptionOneDB::new(path.to_str().unwrap()))
 }
 
 pub fn get_temp_state_in(path: &Path) -> State {

util/src/hashdb.rs

@@ -20,7 +20,7 @@ use bytes::*;
 use std::collections::HashMap;
 
 /// Trait modelling datastore keyed by a 32-byte Keccak hash.
-pub trait HashDB {
+pub trait HashDB : AsHashDB {
 	/// Get the keys in the database together with number of underlying references.
 	fn keys(&self) -> HashMap<H256, i32>;
 
@@ -111,3 +111,16 @@ pub trait HashDB {
 	/// ```
 	fn remove(&mut self, key: &H256) { self.kill(key) }
 }
+
+/// Upcast trait.
+pub trait AsHashDB {
+	/// Perform upcast to HashDB for anything that derives from HashDB.
+	fn as_hashdb(&self) -> &HashDB;
+	/// Perform mutable upcast to HashDB for anything that derives from HashDB.
+	fn as_hashdb_mut(&mut self) -> &mut HashDB;
+}
+
+impl<T: HashDB> AsHashDB for T {
+	fn as_hashdb(&self) -> &HashDB { self }
+	fn as_hashdb_mut(&mut self) -> &mut HashDB { self }
+}

util/src/journaldb.rs

@@ -24,6 +24,22 @@ use kvdb::{Database, DBTransaction, DatabaseConfig};
 #[cfg(test)]
 use std::env;
 
+/// A HashDB which can manage a short-term journal potentially containing many forks of mutually
+/// exclusive actions.
+pub trait JournalDB : HashDB {
+	/// Return a copy of ourself, in a box.
+	fn spawn(&self) -> Box<JournalDB + Send>;
+
+	/// Returns heap memory size used
+	fn mem_used(&self) -> usize;
+
+	/// Check if this database has any commits
+	fn is_empty(&self) -> bool;
+
+	/// Commit all recent insert operations.
+	fn commit(&mut self, now: u64, id: &H256, end: Option<(u64, H256)>) -> Result<u32, UtilError>;
+}
+
 /// Implementation of the HashDB trait for a disk-backed database with a memory overlay
 /// and latent-removal semantics.
 ///
@@ -31,22 +47,12 @@ use std::env;
 /// write operations out to disk. Unlike OverlayDB, `remove()` operations do not take effect
 /// immediately. Rather some age (based on a linear but arbitrary metric) must pass before
 /// the removals actually take effect.
-pub struct JournalDB {
+pub struct OptionOneDB {
 	overlay: MemoryDB,
 	backing: Arc<Database>,
 	counters: Option<Arc<RwLock<HashMap<H256, i32>>>>,
 }
 
-impl Clone for JournalDB {
-	fn clone(&self) -> JournalDB {
-		JournalDB {
-			overlay: MemoryDB::new(),
-			backing: self.backing.clone(),
-			counters: self.counters.clone(),
-		}
-	}
-}
-
 // all keys must be at least 12 bytes
 const LATEST_ERA_KEY : [u8; 12] = [ b'l', b'a', b's', b't', 0, 0, 0, 0, 0, 0, 0, 0 ];
 const VERSION_KEY : [u8; 12] = [ b'j', b'v', b'e', b'r', 0, 0, 0, 0, 0, 0, 0, 0 ];
@@ -56,14 +62,14 @@ const DB_VERSION_NO_JOURNAL : u32 = 3 + 256;
 
 const PADDING : [u8; 10] = [ 0u8; 10 ];
 
-impl JournalDB {
+impl OptionOneDB {
 	/// Create a new instance from file
-	pub fn new(path: &str) -> JournalDB {
+	pub fn new(path: &str) -> OptionOneDB {
 		Self::from_prefs(path, true)
 	}
 
 	/// Create a new instance from file
-	pub fn from_prefs(path: &str, prefer_journal: bool) -> JournalDB {
+	pub fn from_prefs(path: &str, prefer_journal: bool) -> OptionOneDB {
 		let opts = DatabaseConfig {
 			prefix_size: Some(12) //use 12 bytes as prefix, this must match account_db prefix
 		};
@@ -83,11 +89,11 @@ impl JournalDB {
 		}
 
 		let counters = if with_journal {
-			Some(Arc::new(RwLock::new(JournalDB::read_counters(&backing))))
+			Some(Arc::new(RwLock::new(OptionOneDB::read_counters(&backing))))
 		} else {
 			None
 		};
-		JournalDB {
+		OptionOneDB {
 			overlay: MemoryDB::new(),
 			backing: Arc::new(backing),
 			counters: counters,
@@ -96,27 +102,12 @@ impl JournalDB {
 
 	/// Create a new instance with an anonymous temporary database.
 	#[cfg(test)]
-	pub fn new_temp() -> JournalDB {
+	fn new_temp() -> OptionOneDB {
 		let mut dir = env::temp_dir();
 		dir.push(H32::random().hex());
 		Self::new(dir.to_str().unwrap())
 	}
 
-	/// Check if this database has any commits
-	pub fn is_empty(&self) -> bool {
-		self.backing.get(&LATEST_ERA_KEY).expect("Low level database error").is_none()
-	}
-
-	/// Commit all recent insert operations.
-	pub fn commit(&mut self, now: u64, id: &H256, end: Option<(u64, H256)>) -> Result<u32, UtilError> {
-		let have_counters = self.counters.is_some();
-		if have_counters {
-			self.commit_with_counters(now, id, end)
-		} else {
-			self.commit_without_counters()
-		}
-	}
-
 	/// Drain the overlay and place it into a batch for the DB.
 	fn batch_overlay_insertions(overlay: &mut MemoryDB, batch: &DBTransaction) -> usize {
 		let mut inserts = 0usize;
@@ -339,11 +330,11 @@ impl JournalDB {
 				try!(batch.delete(&last));
 				index += 1;
 			}
-			trace!("JournalDB: delete journal for time #{}.{}, (canon was {})", end_era, index, canon_id);
+			trace!("OptionOneDB: delete journal for time #{}.{}, (canon was {})", end_era, index, canon_id);
 		}
 
 		try!(self.backing.write(batch));
-//		trace!("JournalDB::commit() deleted {} nodes", deletes);
+//		trace!("OptionOneDB::commit() deleted {} nodes", deletes);
 		Ok(0)
 	}
 
@@ -379,17 +370,9 @@ impl JournalDB {
 		trace!("Recovered {} counters", counters.len());
 		counters
 	}
+}
 
-	/// Returns heap memory size used
+impl HashDB for OptionOneDB {
-	pub fn mem_used(&self) -> usize {
-		self.overlay.mem_used() + match self.counters {
-			Some(ref c) => c.read().unwrap().heap_size_of_children(),
-			None => 0
-		}
- 	}
- }
-
-impl HashDB for JournalDB {
 	fn keys(&self) -> HashMap<H256, i32> {
 		let mut ret: HashMap<H256, i32> = HashMap::new();
 		for (key, _) in self.backing.iter() {
@@ -434,6 +417,36 @@ impl HashDB for JournalDB {
 	}
 }
 
+impl JournalDB for OptionOneDB {
+	fn spawn(&self) -> Box<JournalDB + Send> {
+		Box::new(OptionOneDB {
+			overlay: MemoryDB::new(),
+			backing: self.backing.clone(),
+			counters: self.counters.clone(),
+		})
+	}
+
+	fn mem_used(&self) -> usize {
+		self.overlay.mem_used() + match self.counters {
+			Some(ref c) => c.read().unwrap().heap_size_of_children(),
+			None => 0
+		}
+ 	}
+
+	fn is_empty(&self) -> bool {
+		self.backing.get(&LATEST_ERA_KEY).expect("Low level database error").is_none()
+	}
+
+	fn commit(&mut self, now: u64, id: &H256, end: Option<(u64, H256)>) -> Result<u32, UtilError> {
+		let have_counters = self.counters.is_some();
+		if have_counters {
+			self.commit_with_counters(now, id, end)
+		} else {
+			self.commit_without_counters()
+		}
+	}
+}
+
 #[cfg(test)]
 mod tests {
 	use common::*;
@@ -443,7 +456,7 @@ mod tests {
 	#[test]
 	fn insert_same_in_fork() {
 		// history is 1
-		let mut jdb = JournalDB::new_temp();
+		let mut jdb = OptionOneDB::new_temp();
 
 		let x = jdb.insert(b"X");
 		jdb.commit(1, &b"1".sha3(), None).unwrap();
@@ -465,7 +478,7 @@ mod tests {
 	#[test]
 	fn long_history() {
 		// history is 3
-		let mut jdb = JournalDB::new_temp();
+		let mut jdb = OptionOneDB::new_temp();
 		let h = jdb.insert(b"foo");
 		jdb.commit(0, &b"0".sha3(), None).unwrap();
 		assert!(jdb.exists(&h));
@@ -483,7 +496,7 @@ mod tests {
 	#[test]
 	fn complex() {
 		// history is 1
-		let mut jdb = JournalDB::new_temp();
+		let mut jdb = OptionOneDB::new_temp();
 
 		let foo = jdb.insert(b"foo");
 		let bar = jdb.insert(b"bar");
@@ -521,7 +534,7 @@ mod tests {
 	#[test]
 	fn fork() {
 		// history is 1
-		let mut jdb = JournalDB::new_temp();
+		let mut jdb = OptionOneDB::new_temp();
 
 		let foo = jdb.insert(b"foo");
 		let bar = jdb.insert(b"bar");
@@ -549,7 +562,7 @@ mod tests {
 	#[test]
 	fn overwrite() {
 		// history is 1
-		let mut jdb = JournalDB::new_temp();
+		let mut jdb = OptionOneDB::new_temp();
 
 		let foo = jdb.insert(b"foo");
 		jdb.commit(0, &b"0".sha3(), None).unwrap();
@@ -568,7 +581,7 @@ mod tests {
 	#[test]
 	fn fork_same_key() {
 		// history is 1
-		let mut jdb = JournalDB::new_temp();
+		let mut jdb = OptionOneDB::new_temp();
 		jdb.commit(0, &b"0".sha3(), None).unwrap();
 
 		let foo = jdb.insert(b"foo");
@@ -590,7 +603,7 @@ mod tests {
 		let bar = H256::random();
 
 		let foo = {
-			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			let mut jdb = OptionOneDB::new(dir.to_str().unwrap());
 			// history is 1
 			let foo = jdb.insert(b"foo");
 			jdb.emplace(bar.clone(), b"bar".to_vec());
@@ -599,13 +612,13 @@ mod tests {
 		};
 
 		{
-			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			let mut jdb = OptionOneDB::new(dir.to_str().unwrap());
 			jdb.remove(&foo);
 			jdb.commit(1, &b"1".sha3(), Some((0, b"0".sha3()))).unwrap();
 		}
 
 		{
-			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			let mut jdb = OptionOneDB::new(dir.to_str().unwrap());
 			assert!(jdb.exists(&foo));
 			assert!(jdb.exists(&bar));
 			jdb.commit(2, &b"2".sha3(), Some((1, b"1".sha3()))).unwrap();
@@ -619,7 +632,7 @@ mod tests {
 		dir.push(H32::random().hex());
 
 		let foo = {
-			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			let mut jdb = OptionOneDB::new(dir.to_str().unwrap());
 			// history is 1
 			let foo = jdb.insert(b"foo");
 			jdb.commit(0, &b"0".sha3(), None).unwrap();
@@ -633,7 +646,7 @@ mod tests {
 		};
 
 		{
-			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			let mut jdb = OptionOneDB::new(dir.to_str().unwrap());
 			jdb.remove(&foo);
 			jdb.commit(3, &b"3".sha3(), Some((2, b"2".sha3()))).unwrap();
 			assert!(jdb.exists(&foo));
@@ -648,7 +661,7 @@ mod tests {
 		let mut dir = ::std::env::temp_dir();
 		dir.push(H32::random().hex());
 		let (foo, bar, baz) = {
-			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			let mut jdb = OptionOneDB::new(dir.to_str().unwrap());
 			// history is 1
 			let foo = jdb.insert(b"foo");
 			let bar = jdb.insert(b"bar");
@@ -663,7 +676,7 @@ mod tests {
 		};
 
 		{
-			let mut jdb = JournalDB::new(dir.to_str().unwrap());
+			let mut jdb = OptionOneDB::new(dir.to_str().unwrap());
 			jdb.commit(2, &b"2b".sha3(), Some((1, b"1b".sha3()))).unwrap();
 			assert!(jdb.exists(&foo));
 			assert!(!jdb.exists(&baz));

util/src/overlaydb.rs

@@ -36,6 +36,7 @@ use kvdb::{Database};
 ///
 /// `lookup()` and `contains()` maintain normal behaviour - all `insert()` and `remove()` 
 /// queries have an immediate effect in terms of these functions.
+#[derive(Clone)]
 pub struct OverlayDB {
 	overlay: MemoryDB,
 	backing: Arc<Database>,