/******************************************************************************
 * Icinga 2                                                                   *
 * Copyright (C) 2012-2013 Icinga Development Team (http://www.icinga.org/)   *
 *                                                                            *
 * 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 2             *
 * 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, write to the Free Software Foundation     *
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.             *
 ******************************************************************************/

#include "base/thinmutex.hpp"
#include "base/initialize.hpp"
#include "base/timer.hpp"
#include "base/convert.hpp"
#include "base/logger.hpp"
#include <boost/thread.hpp>

using namespace icinga;

#ifdef _DEBUG
uintptr_t ThinMutex::m_TotalMutexes;
uintptr_t ThinMutex::m_InflatedMutexes;
uintptr_t ThinMutex::m_DeadMutexes;

static Timer::Ptr l_Timer;

void ThinMutex::DebugTimerHandler(void)
{
	Log(LogNotice, "ThinMutex")
	    << "Mutexes: " << ThinMutex::m_TotalMutexes - ThinMutex::m_DeadMutexes
	    << ", Inflated Mutexes: " << ThinMutex::m_InflatedMutexes
	    << ", Dead Mutexes: " << ThinMutex::m_DeadMutexes;
}

static void InitThinMutex(void)
{
	l_Timer = new Timer();
	l_Timer->SetInterval(10);
	l_Timer->OnTimerExpired.connect(boost::bind(&ThinMutex::DebugTimerHandler));
	l_Timer->Start();
}

INITIALIZE_ONCE(&InitThinMutex);
#endif /* _DEBUG */

void ThinMutex::LockSlowPath(void)
{
	LockSlowPath(false);
}

void ThinMutex::LockSlowPath(bool make_native)
{
	unsigned int it = 0;

#ifdef _WIN32
#	ifdef _WIN64
	while (InterlockedCompareExchange64(&m_Data, THINLOCK_LOCKED, THINLOCK_UNLOCKED) != THINLOCK_UNLOCKED) {
#	else /* _WIN64 */
	while (InterlockedCompareExchange(&m_Data, THINLOCK_LOCKED, THINLOCK_UNLOCKED) != THINLOCK_UNLOCKED) {
#	endif /* _WIN64 */
#else /* _WIN32 */
	while (!__sync_bool_compare_and_swap(&m_Data, THINLOCK_UNLOCKED, THINLOCK_LOCKED)) {
#endif /* _WIN32 */
		if (m_Data > THINLOCK_LOCKED) {
			LockNative();
			return;
		}

		make_native = true;

		Spin(it);
		it++;
	}

	if (make_native)
		MakeNative();
}

void ThinMutex::MakeNative(void)
{
	boost::mutex *mtx = new boost::mutex();
	mtx->lock();
#ifdef _WIN32
#	ifdef _WIN64
	InterlockedCompareExchange64(&m_Data, reinterpret_cast<LONGLONG>(mtx), THINLOCK_LOCKED);
#	else /* _WIN64 */
	InterlockedCompareExchange(&m_Data, reinterpret_cast<LONG>(mtx), THINLOCK_LOCKED);
#	endif /* _WIN64 */
#else /* _WIN32 */
	__sync_bool_compare_and_swap(&m_Data, THINLOCK_LOCKED, reinterpret_cast<uintptr_t>(mtx));
#endif /* _WIN32 */

#ifdef _DEBUG
#	ifdef _WIN32
	InterlockedIncrement(&m_InflatedMutexes);
#	else /* _WIN32 */
	__sync_fetch_and_add(&m_InflatedMutexes, 1);
#	endif /* _WIN32 */
#endif /* _DEBUG */
}

void ThinMutex::DestroyNative(void)
{
	delete reinterpret_cast<boost::mutex *>(m_Data);
}

void ThinMutex::LockNative(void)
{
	boost::mutex *mtx = reinterpret_cast<boost::mutex *>(m_Data);
	mtx->lock();
}

void ThinMutex::UnlockNative(void)
{
	boost::mutex *mtx = reinterpret_cast<boost::mutex *>(m_Data);
	mtx->unlock();
}