From 6067c939cdb867d84f2b355acceb6834814aaf1f Mon Sep 17 00:00:00 2001
From: Gav Wood <i@gavwood.com>
Date: Mon, 13 Apr 2015 22:49:17 +0200
Subject: [PATCH] Fix CPU mining deadlock bug.

---
 exp/main.cpp       | 74 +++++++++++++++++++++++++++++++++++++++++++++-
 libethcore/Miner.h |  6 ++--
 libethereum/Farm.h |  4 ++-
 3 files changed, 78 insertions(+), 6 deletions(-)

diff --git a/exp/main.cpp b/exp/main.cpp
index 2055c49e1..54b75d0e2 100644
--- a/exp/main.cpp
+++ b/exp/main.cpp
@@ -25,6 +25,7 @@
 #include "libethash-cl/cl.hpp"
 #endif
 #include <functional>
+#include <boost/filesystem.hpp>
 #include <libdevcore/RangeMask.h>
 #include <libdevcore/Log.h>
 #include <libdevcore/Common.h>
@@ -106,7 +107,7 @@ int main()
 	cnote << "State after transaction: " << s;
 	cnote << before.diff(s);
 }
-#else
+#elif 0
 int main()
 {
 	GenericFarm<Ethash> f;
@@ -152,5 +153,76 @@ int main()
 
 	return 0;
 }
+#else
+
+void mine(State& s, BlockChain const& _bc)
+{
+	s.commitToMine(_bc);
+	GenericFarm<ProofOfWork> f;
+	bool completed = false;
+	f.onSolutionFound([&](ProofOfWork::Solution sol)
+	{
+		return completed = s.completeMine<ProofOfWork>(sol);
+	});
+	f.setWork(s.info());
+	f.startCPU();
+	while (!completed)
+		this_thread::sleep_for(chrono::milliseconds(20));
+}
+
+int main()
+{
+	cnote << "Testing State...";
+
+	KeyPair me = sha3("Gav Wood");
+	KeyPair myMiner = sha3("Gav's Miner");
+//	KeyPair you = sha3("123");
+
+	Defaults::setDBPath(boost::filesystem::temp_directory_path().string() + "/" + toString(chrono::system_clock::now().time_since_epoch().count()));
+
+	OverlayDB stateDB = State::openDB();
+	CanonBlockChain bc;
+	cout << bc;
+
+	State s(stateDB, BaseState::CanonGenesis, myMiner.address());
+	cout << s;
+
+	// Sync up - this won't do much until we use the last state.
+	s.sync(bc);
+
+	cout << s;
+
+	// Mine to get some ether!
+	mine(s, bc);
+
+	bc.attemptImport(s.blockData(), stateDB);
+
+	cout << bc;
+
+	s.sync(bc);
+
+	cout << s;
+
+	// Inject a transaction to transfer funds from miner to me.
+	Transaction t(1000, 10000, 30000, me.address(), bytes(), s.transactionsFrom(myMiner.address()), myMiner.secret());
+	assert(t.sender() == myMiner.address());
+	s.execute(bc.lastHashes(), t);
+
+	cout << s;
+
+	// Mine to get some ether and set in stone.
+	s.commitToMine(bc);
+	s.commitToMine(bc);
+	mine(s, bc);
+	bc.attemptImport(s.blockData(), stateDB);
+
+	cout << bc;
+
+	s.sync(bc);
+
+	cout << s;
+
+	return 0;
+}
 #endif
 
diff --git a/libethcore/Miner.h b/libethcore/Miner.h
index 084cc59ff..a048b0238 100644
--- a/libethcore/Miner.h
+++ b/libethcore/Miner.h
@@ -69,11 +69,11 @@ public:
 	/**
 	 * @brief Called from a Miner to note a WorkPackage has a solution.
 	 * @param _p The solution.
-	 * @param _wp The WorkPackage that the Solution is for.
+	 * @param _wp The WorkPackage that the Solution is for; this will be reset if the work is accepted.
 	 * @param _finder The miner that found it.
 	 * @return true iff the solution was good (implying that mining should be .
 	 */
-	virtual bool submitProof(Solution const& _p, WorkPackage const& _wp, Miner* _finder) = 0;
+	virtual bool submitProof(Solution const& _p, WorkPackage& io_wp, Miner* _finder) = 0;
 };
 
 /**
@@ -139,10 +139,8 @@ protected:
 	{
 		if (m_farm)
 		{
-			Guard l(x_work);
 			if (!m_farm->submitProof(_s, m_work, this))
 				return false;
-			m_work.reset();
 			return true;
 		}
 		return true;
diff --git a/libethereum/Farm.h b/libethereum/Farm.h
index 6b65e37c2..56bbcb9df 100644
--- a/libethereum/Farm.h
+++ b/libethereum/Farm.h
@@ -136,8 +136,9 @@ private:
 	 * @param _wp The WorkPackage that the Solution is for.
 	 * @return true iff the solution was good (implying that mining should be .
 	 */
-	bool submitProof(Solution const& _s, WorkPackage const& _wp, Miner* _m) override
+	bool submitProof(Solution const& _s, WorkPackage& _wp, Miner* _m) override
 	{
+		ReadGuard l(x_work);
 		if (_wp.headerHash != m_work.headerHash)
 			return false;
 
@@ -147,6 +148,7 @@ private:
 			for (std::shared_ptr<Miner> const& m: m_miners)
 				if (m.get() != _m)
 					m->setWork();
+			_wp.reset();
 			m_work.reset();
 			return true;
 		}