openEMS/FDTD/engine_multithread.cpp

/*
*	Copyright (C) 2010 Sebastian Held (sebastian.held@gmx.de)
*
*	This program is free software: you can redistribute it and/or modify
*	it under the terms of the GNU General Public License as published by
*	the Free Software Foundation, either version 3 of the License, or
*	(at your option) any later version.
*
*	This program is distributed in the hope that it will be useful,
*	but WITHOUT ANY WARRANTY; without even the implied warranty of
*	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*	GNU General Public License for more details.
*
*	You should have received a copy of the GNU General Public License
*	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

//#define ENABLE_DEBUG_TIME

#ifdef ENABLE_DEBUG_TIME
	#define DEBUG_TIME(x) x;
#else
	#define DEBUG_TIME(x) ;
#endif



#include "engine_multithread.h"
#include "engine_extension.h"
#include "tools/array_ops.h"

#include "boost/date_time/posix_time/posix_time.hpp"
#include "boost/date_time/gregorian/gregorian.hpp"
#include <iomanip>

//! \brief construct an Engine_Multithread instance
//! it's the responsibility of the caller to free the returned pointer
Engine_Multithread* Engine_Multithread::New(const Operator_Multithread* op, unsigned int numThreads)
{
	cout << "Create FDTD engine (compressed SSE + multi-threading)" << endl;
	Engine_Multithread* e = new Engine_Multithread(op);
	e->setNumThreads( numThreads );
	e->Init();
	return e;
}

Engine_Multithread::Engine_Multithread(const Operator_SSE_Compressed* op) : Engine_SSE_Compressed(op)
{
	m_type = SSE;
	m_barrier_VoltUpdate = 0;
	m_barrier_VoltExcite = 0;
	m_barrier_PreVolt = 0;
	m_barrier_PostVolt = 0;
	m_barrier_CurrUpdate = 0;
	m_barrier_CurrExcite = 0;
	m_barrier_PreCurr = 0;
	m_barrier_PostCurr = 0;
	m_startBarrier = 0;
	m_stopBarrier = 0;
}

Engine_Multithread::~Engine_Multithread()
{
#ifdef ENABLE_DEBUG_TIME
	NS_Engine_Multithread::DBG().cout() << "Engine_Multithread::~Engine_Multithread()" << endl;
	std::map<boost::thread::id, std::vector<double> >::iterator it;
	for (it=m_timer_list.begin(); it!=m_timer_list.end(); it++) {
		NS_Engine_Multithread::DBG().cout() << "*** DEBUG Thread: " << it->first << std::endl;
		std::vector<double>::iterator it2;
		for (it2=it->second.begin(); it2<it->second.end();) {
			NS_Engine_Multithread::DBG().cout() << "after voltage update, before barrier1: " << fixed << setprecision(6) << *(it2++) << std::endl;
			NS_Engine_Multithread::DBG().cout() << "after barrier1, before barrier2: "       << fixed << setprecision(6) << *(it2++) << std::endl;
			NS_Engine_Multithread::DBG().cout() << "after barrier2, before current update: " << fixed << setprecision(6) << *(it2++) << std::endl;
			NS_Engine_Multithread::DBG().cout() << "after current update, before barrier3: " << fixed << setprecision(6) << *(it2++) << std::endl;
			NS_Engine_Multithread::DBG().cout() << "after barrier3: "                        << fixed << setprecision(6) << *(it2++) << std::endl;
		}
	}
#endif

	Reset();
}

void Engine_Multithread::setNumThreads( unsigned int numThreads )
{
	m_numThreads = numThreads;
}

void Engine_Multithread::Init()
{
	m_stopThreads = true;
	Engine_SSE_Compressed::Init();

	// initialize threads
	m_stopThreads = false;
	if (m_numThreads == 0)
		m_numThreads = boost::thread::hardware_concurrency();

	unsigned int linesPerThread = round((float)numLines[0] / (float)m_numThreads);
	if ((m_numThreads-1) * linesPerThread >= numLines[0])
		--m_numThreads;

	cout << "Multithreaded engine using " << m_numThreads << " threads. Utilization: (";
	m_barrier_VoltUpdate = new boost::barrier(m_numThreads); // numThread workers
	m_barrier_VoltExcite = new boost::barrier(m_numThreads+1); // numThread workers + 1 excitation thread
	m_barrier_CurrUpdate = new boost::barrier(m_numThreads); // numThread workers
	m_barrier_CurrExcite = new boost::barrier(m_numThreads+1); // numThread workers + 1 excitation thread

	m_barrier_PreVolt = new boost::barrier(m_numThreads); // numThread workers
	m_barrier_PostVolt = new boost::barrier(m_numThreads+1); // numThread workers + 1 excitation thread
	m_barrier_PreCurr = new boost::barrier(m_numThreads); // numThread workers
	m_barrier_PostCurr = new boost::barrier(m_numThreads+1); // numThread workers + 1 excitation thread

	m_startBarrier = new boost::barrier(m_numThreads+1); // numThread workers + 1 controller
	m_stopBarrier = new boost::barrier(m_numThreads+1); // numThread workers + 1 controller

	for (unsigned int n=0; n<m_numThreads; n++) {
		unsigned int start = n * linesPerThread;
		unsigned int stop = (n+1) * linesPerThread - 1;
		unsigned int stop_h = stop;
		if (n == m_numThreads-1) {
			// last thread
			stop = numLines[0]-1;
			stop_h = stop-1;
			cout << stop-start+1 << ")" << endl;
		}
		else
			cout << stop-start+1 << ";";
//		NS_Engine_Multithread::DBG().cout() << "###DEBUG## Thread " << n << ": start=" << start << " stop=" << stop  << " stop_h=" << stop_h << std::endl;
		boost::thread *t = new boost::thread( NS_Engine_Multithread::thread(this,start,stop,stop_h,n) );
		m_thread_group.add_thread( t );
	}
	boost::thread *t = new boost::thread( NS_Engine_Multithread::thread_e_excitation(this) );
	m_thread_group.add_thread( t );
}

void Engine_Multithread::Reset()
{
	if (!m_stopThreads) {
		// prevent multiple invocations

		// stop the threads
		//NS_Engine_Multithread::DBG().cout() << "stopping all threads" << endl;
		m_iterTS = 1;
		m_startBarrier->wait(); // start the threads
		m_stopThreads = true;
		m_stopBarrier->wait(); // wait for the threads to finish
		m_thread_group.join_all(); // wait for termination
		delete m_barrier_VoltUpdate; m_barrier_VoltUpdate = 0;
		delete m_barrier_VoltExcite; m_barrier_VoltExcite = 0;
		delete m_barrier_PreVolt; m_barrier_PreVolt = 0;
		delete m_barrier_PostVolt; m_barrier_PostVolt = 0;
		delete m_barrier_CurrUpdate; m_barrier_CurrUpdate = 0;
		delete m_barrier_CurrExcite; m_barrier_CurrExcite = 0;
		delete m_barrier_PreCurr; m_barrier_PreCurr = 0;
		delete m_barrier_PostCurr; m_barrier_PostCurr = 0;
		delete m_startBarrier; m_startBarrier = 0;
		delete m_stopBarrier; m_stopBarrier = 0;
	}

	Engine_SSE_Compressed::Reset();
}

bool Engine_Multithread::IterateTS(unsigned int iterTS)
{
	m_iterTS = iterTS;

	//cout << "bool Engine_Multithread::IterateTS(): starting threads ...";
	m_startBarrier->wait(); // start the threads

	//cout << "... threads started";

	m_stopBarrier->wait(); // wait for the threads to finish <iterTS> time steps
	return true;
}

//
// *************************************************************************************************************************
//
namespace NS_Engine_Multithread {

thread::thread( Engine_Multithread* ptr, unsigned int start, unsigned int stop, unsigned int stop_h, unsigned int threadID )
{
	m_enginePtr = ptr;
	m_start = start;
	m_stop = stop;
	m_stop_h = stop_h;
	m_threadID = threadID;
}

void thread::operator()()
{
	//std::cout << "thread::operator() Parameters: " << m_start << " " << m_stop << std::endl;
	//DBG().cout() << "Thread " << m_threadID << " (" << boost::this_thread::get_id() << ") started." << endl;


	while (!m_enginePtr->m_stopThreads) {
		// wait for start
		//DBG().cout() << "Thread " << m_threadID << " (" << boost::this_thread::get_id() << ") waiting..." << endl;
		m_enginePtr->m_startBarrier->wait();
		//cout << "Thread " << boost::this_thread::get_id() << " waiting... started." << endl;

		DEBUG_TIME( Timer timer1 );

		for (unsigned int iter=0;iter<m_enginePtr->m_iterTS;++iter)
		{
			// pre voltage stuff...
			for (size_t n=m_threadID;n<m_enginePtr->GetExtensionCount();n+=m_enginePtr->m_numThreads)
				m_enginePtr->GetExtension(n)->DoPreVoltageUpdates();

			m_enginePtr->m_barrier_PreVolt->wait();

			//voltage updates
			m_enginePtr->UpdateVoltages(m_start,m_stop-m_start+1);

			// record time
			DEBUG_TIME( m_enginePtr->m_timer_list[boost::this_thread::get_id()].push_back( timer1.elapsed() ); )

			//cout << "Thread " << boost::this_thread::get_id() << " m_barrier1 waiting..." << endl;
			m_enginePtr->m_barrier_VoltUpdate->wait();

			// record time
			DEBUG_TIME( m_enginePtr->m_timer_list[boost::this_thread::get_id()].push_back( timer1.elapsed() ); )

			//post voltage stuff...
			for (size_t n=m_threadID;n<m_enginePtr->GetExtensionCount();n+=m_enginePtr->m_numThreads)
				m_enginePtr->GetExtension(n)->DoPostVoltageUpdates();
			m_enginePtr->m_barrier_PostVolt->wait();

			// e-field excitation (thread thread_e_excitation)
			m_enginePtr->m_barrier_VoltExcite->wait();
			// e_excitation finished

			// record time
			DEBUG_TIME( m_enginePtr->m_timer_list[boost::this_thread::get_id()].push_back( timer1.elapsed() ); )

			//pre current stuff
			for (size_t n=m_threadID;n<m_enginePtr->GetExtensionCount();n+=m_enginePtr->m_numThreads)
				m_enginePtr->GetExtension(n)->DoPreCurrentUpdates();
			m_enginePtr->m_barrier_PreCurr->wait();

			//current updates
			m_enginePtr->UpdateCurrents(m_start,m_stop_h-m_start+1);

			// record time
			DEBUG_TIME( m_enginePtr->m_timer_list[boost::this_thread::get_id()].push_back( timer1.elapsed() ); )
			m_enginePtr->m_barrier_CurrUpdate->wait();

			// record time
			DEBUG_TIME( m_enginePtr->m_timer_list[boost::this_thread::get_id()].push_back( timer1.elapsed() ); )

			//post current stuff
			for (size_t n=m_threadID;n<m_enginePtr->GetExtensionCount();n+=m_enginePtr->m_numThreads)
				m_enginePtr->GetExtension(n)->DoPostCurrentUpdates();
			m_enginePtr->m_barrier_PostCurr->wait();

			//soft current excitation here (H-field excite)
			m_enginePtr->m_barrier_CurrExcite->wait();
			// excitation finished

			if (m_threadID == 0)
				++m_enginePtr->numTS; // only the first thread increments numTS
		}

		m_enginePtr->m_stopBarrier->wait();
	}

	//DBG().cout() << "Thread " << m_threadID << " (" << boost::this_thread::get_id() << ") finished." << endl;
}

} // namespace

//
// *************************************************************************************************************************
//
namespace NS_Engine_Multithread {

thread_e_excitation::thread_e_excitation( Engine_Multithread* ptr )
{
	m_enginePtr = ptr;
}

void thread_e_excitation::operator()()
{
	//std::cout << "thread_e_excitation::operator()" << std::endl;
	//DBG().cout() << "Thread e_excitation (" << boost::this_thread::get_id() << ") started." << endl;

	while (!m_enginePtr->m_stopThreads)
	{
		m_enginePtr->m_barrier_PostVolt->wait(); // waiting on NS_Engine_Multithread::thread

		for (size_t n=0;n<m_enginePtr->GetExtensionCount();++n)
			m_enginePtr->GetExtension(n)->Apply2Voltages();

		m_enginePtr->ApplyVoltageExcite();

		m_enginePtr->m_barrier_VoltExcite->wait(); // continue NS_Engine_Multithread::thread


		m_enginePtr->m_barrier_PostCurr->wait(); // waiting on NS_Engine_Multithread::thread

		for (size_t n=0;n<m_enginePtr->GetExtensionCount();++n)
			m_enginePtr->GetExtension(n)->Apply2Current();

		m_enginePtr->ApplyCurrentExcite();

		m_enginePtr->m_barrier_CurrExcite->wait(); // continue NS_Engine_Multithread::thread
	}

	//DBG().cout() << "Thread e_excitation (" << boost::this_thread::get_id() << ") finished." << endl;
}

} // namespace