// ***************************************************************************
//
// Reality - The Matrix Online Server Emulator
// Copyright (C) 2006-2010 Rajko Stojadinovic
// http://mxoemu.info
//
// ---------------------------------------------------------------------------
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
//
// ---------------------------------------------------------------------------
//
// ***************************************************************************

#ifndef MXOSIM_MUTEX_H
#define MXOSIM_MUTEX_H

#include "../Common.h"

class NativeMutex
{
public:
	friend class Condition;

	/** Initializes a mutex class, with InitializeCriticalSection / pthread_mutex_init
	 */
	NativeMutex();

	/** Deletes the associated critical section / mutex
	 */
	~NativeMutex();

	/** Acquires this mutex. If it cannot be acquired immediately, it will block.
	 */
	inline void Acquire()
	{
#if PLATFORM != PLATFORM_WIN32
		pthread_mutex_lock(&mutex);
#else
		EnterCriticalSection(&cs);
#endif
	}

	/** Releases this mutex. No error checking performed
	 */
	inline void Release()
	{
#if PLATFORM != PLATFORM_WIN32
		pthread_mutex_unlock(&mutex);
#else
		LeaveCriticalSection(&cs);
#endif
	}

	/** Attempts to acquire this mutex. If it cannot be acquired (held by another thread)
	 * it will return false.
	 * @return false if cannot be acquired, true if it was acquired.
	 */
	inline bool AttemptAcquire()
	{
#if PLATFORM != PLATFORM_WIN32
		return (pthread_mutex_trylock(&mutex) == 0);
#else
		return (TryEnterCriticalSection(&cs) == TRUE ? true : false);
#endif
	}

protected:
#if PLATFORM == PLATFORM_WIN32
	/** Critical section used for system calls
	 */
	CRITICAL_SECTION cs;

#else
	/** Static mutex attribute
	 */
	static bool attr_initalized;
	static pthread_mutexattr_t attr;

	/** pthread struct used in system calls
	 */
	pthread_mutex_t mutex;
#endif
};

#if PLATFORM == PLATFORM_WIN32

class FastMutex
{
#pragma pack(push,8)
	volatile long m_lock;
#pragma pack(pop)
	DWORD m_recursiveCount;

public:
	inline FastMutex() : m_lock(0),m_recursiveCount(0) {}
	inline ~FastMutex() {}

	inline void Acquire()
	{
		DWORD thread_id = GetCurrentThreadId(), owner;
		if(thread_id == (DWORD)m_lock)
		{
			++m_recursiveCount;
			return;
		}

		for(;;)
		{
			owner = InterlockedCompareExchange(&m_lock, thread_id, 0);
			if(owner == 0)
				break;

			Sleep(0);
		}

		++m_recursiveCount;
	}

	inline bool AttemptAcquire()
	{
		DWORD thread_id = GetCurrentThreadId();
		if(thread_id == (DWORD)m_lock)
		{
			++m_recursiveCount;
			return true;
		}

		DWORD owner = InterlockedCompareExchange(&m_lock, thread_id, 0);
		if(owner == 0)
		{
			++m_recursiveCount;
			return true;
		}

		return false;
	}

	inline void Release()
	{
		if((--m_recursiveCount) == 0)
			InterlockedExchange(&m_lock, 0);
	}
};

#else

#define FastMutex NativeMutex

#endif

#endif /* MXOSIM_MUTEX_H */