Do to set empty work

The farm sometimes sends empty work package to miners. The setWork() has magic side effects of restarting miners. We want to get rid of this -- miners should not be restarted this way.

Author: chfast

ethminer/MinerAux.h

@@ -614,11 +614,11 @@ class MinerCLI
 		//genesis.prep();
 
 		genesis.setDifficulty(u256(1) << 63);
-		f.setWork(genesis);
 		if (_m == MinerType::CL)
 			f.start("opencl", false);
 		else if (_m == MinerType::CUDA)
 			f.start("cuda", false);
+		f.setWork(genesis);
 
 		map<uint64_t, WorkingProgress> results;
 		uint64_t mean = 0;
@@ -677,12 +677,12 @@ class MinerCLI
 		//genesis.prep();
 
 		genesis.setDifficulty(u256(1) << difficulty);
-		f.setWork(genesis);
 
 		if (_m == MinerType::CL)
 			f.start("opencl", false);
 		else if (_m == MinerType::CUDA)
 			f.start("cuda", false);
+		f.setWork(genesis);
 
 		int time = 0;
 

libdevcore/Worker.h

@@ -41,7 +41,7 @@ enum class WorkerState
 
 class Worker
 {
-protected:
+public:
 	Worker(std::string const& _name): m_name(_name) {}
 
 	Worker(Worker const&) = delete;
@@ -55,11 +55,11 @@ class Worker
 	/// Stop worker thread; causes call to stopWorking().
 	void stopWorking();
 
-	virtual void workLoop() = 0;
-
 	bool shouldStop() const { return m_state != WorkerState::Started; }
 
 private:
+	virtual void workLoop() = 0;
+
 	std::string m_name;
 
 	mutable Mutex x_work;						///< Lock for the network existance.

libethash-cl/CLMiner.cpp

@@ -143,7 +143,14 @@ void CLMiner::workLoop()
 	// take local copy of work since it may end up being overwritten by kickOff/pause.
 	try {
 		const WorkPackage w = work();
-		cllog << "Set work. Header" << w.header << "target" << w.boundary.hex().substr(0, 12);
+
+		if (!w)
+		{
+			cllog << "No work. Pause.";
+			return;
+		}
+
+		cllog << "Set work. Header" << w.header << "target" << w.boundary.hex();
 		if (m_seed != w.seed)
 		{
 			if (s_dagLoadMode == DAG_LOAD_MODE_SEQUENTIAL)

libethcore/Farm.h

@@ -100,8 +100,12 @@ class Farm: public FarmFace
 		}
 		for (unsigned i = start; i < ins; ++i)
 		{
+			// TODO: Improve miners creation, use unique_ptr.
 			m_miners.push_back(std::shared_ptr<Miner>(m_sealers[_sealer].create(*this, i)));
-			m_miners.back()->setWork(m_work);
+
+			// Start miners' threads. They should pause waiting for new work
+			// package.
+			m_miners.back()->startWorking();
 		}
 		m_isMining = true;
 		m_lastSealer = _sealer;

libethcore/Miner.h

@@ -155,6 +155,7 @@ class Miner: public Worker
 			Guard l(x_work);
 			m_work = _work;
 		}
+		assert(!!_work);
 		if (!!_work)
 		{
 			pause();