Fix for state race condition.

libethereum/Client.cpp

@@ -267,6 +267,7 @@ void Client::work()
 		{
 			// Import block.
 			lock_guard<recursive_mutex> l(m_lock);
+			m_postMine.completeMine();
 			m_bc.attemptImport(m_postMine.blockData(), m_stateDB);
 			m_changed = true;
 		}

libethereum/State.cpp

@@ -750,8 +750,15 @@ MineInfo State::mine(uint _msTimeout)
 	m_currentBlock.difficulty = m_currentBlock.calculateDifficulty(m_previousBlock);
 
 	// TODO: Miner class that keeps dagger between mine calls (or just non-polling mining).
-	MineInfo ret = m_dagger.mine(/*out*/m_currentBlock.nonce, m_currentBlock.headerHashWithoutNonce(), m_currentBlock.difficulty, _msTimeout);
-	if (ret.completed)
+	auto ret = m_dagger.mine(/*out*/m_currentBlock.nonce, m_currentBlock.headerHashWithoutNonce(), m_currentBlock.difficulty, _msTimeout);
+
+	if (!ret.completed)
+		m_currentBytes.clear();
+
+	return ret;
+}
+
+void State::completeMine()
 {
 	// Got it!
 
@@ -768,11 +775,6 @@ MineInfo State::mine(uint _msTimeout)
 	m_currentBlock.hash = sha3(m_currentBytes);
 	cnote << "Mined " << m_currentBlock.hash << "(parent: " << m_currentBlock.parentHash << ")";
 }
-	else
-		m_currentBytes.clear();
-
-	return ret;
-}
 
 bool State::addressInUse(Address _id) const
 {
@@ -943,9 +945,18 @@ bool State::isTrieGood(bool _enforceRefs, bool _requireNoLeftOvers) const
 	return true;
 }
 
-// TODO: kill temp nodes automatically in TrieDB
+// TODO: run this often.
+// POSSIBLE RACE CONDITION: check if mining clears intermediate nodes in trie before clearing pending.
+// HOW DID TRIE NODES GO BUT PENDING STAY?
+void State::checkPendingInTrie() const
+{
+	bool x = true;
+
+
+	assert(x);
+}
+
 // TODO: maintain node overlay revisions for stateroots -> each commit gives a stateroot + OverlayDB; allow overlay copying for rewind operations.
-// TODO: TransactionReceipt trie should be MemoryDB and built as necessary
 
 u256 State::execute(bytesConstRef _rlp)
 {

libethereum/State.h

@@ -149,11 +149,26 @@ public:
 	void commitToMine(BlockChain const& _bc);
 
 	/// Attempt to find valid nonce for block that this state represents.
+	/// This function is thread-safe. You can safely have other interactions with this object while it is happening.
 	/// @param _msTimeout Timeout before return in milliseconds.
-	/// @returns a non-empty byte array containing the block if it got lucky. In this case, call blockData()
-	/// to get the block if you need it later.
+	/// @returns Information on the mining.
 	MineInfo mine(uint _msTimeout = 1000);
 
+	/** Commit to DB and build the final block if the previous call to mine()'s result is completion.
+	 * Typically looks like:
+	 * @code
+	 * // lock
+	 * commitToMine(blockchain);
+	 * // unlock
+	 * MineInfo info;
+	 * for (info.complete = false; !info.complete; info = mine()) {}
+	 * // lock
+	 * completeMine();
+	 * // unlock
+	 * @endcode
+	 */
+	void completeMine();
+
 	/// Get the complete current block, including valid nonce.
 	/// Only valid after mine() returns true.
 	bytes const& blockData() const { return m_currentBytes; }
@@ -309,6 +324,7 @@ private:
 
 	bool isTrieGood(bool _enforceRefs, bool _requireNoLeftOvers) const;
 	void paranoia(std::string const& _when, bool _enforceRefs = false) const;
+	void checkPendingInTrie() const;
 
 	OverlayDB m_db;								///< Our overlay for the state tree.
 	TrieDB<Address, OverlayDB> m_state;			///< Our state tree, as an OverlayDB DB.

test/state.cpp

@@ -51,7 +51,8 @@ int stateTest()
 
 	// Mine to get some ether!
 	s.commitToMine(bc);
-	while (s.mine(100).completed) {}
+	while (!s.mine(100).completed) {}
+	s.completeMine();
 	bc.attemptImport(s.blockData(), stateDB);
 
 	cout << bc;
@@ -77,7 +78,8 @@ int stateTest()
 
 	// Mine to get some ether and set in stone.
 	s.commitToMine(bc);
-	while (s.mine(100).completed) {}
+	while (!s.mine(100).completed) {}
+	s.completeMine();
 	bc.attemptImport(s.blockData(), stateDB);
 
 	cout << bc;