// ***************************************************************************
//
// 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/>.
//
// ---------------------------------------------------------------------------
//
// ***************************************************************************

#include "../Common.h"
#include "NativeMutex.h"
#include "ThreadStarter.h"
#include "../Errors.h"

#ifndef MXOSIM_THREADPOOL_H
#define MXOSIM_THREADPOOL_H

#define THREAD_RESERVE 8

#if PLATFORM == PLATFORM_WIN32

class ThreadController
{
public:
	HANDLE hThread;
	uint32 thread_id;

	void Setup(HANDLE h)
	{
		hThread = h;
	}

	void Suspend()
	{
		// We can't be suspended by someone else. That is a big-no-no and will lead to crashes.
		ASSERT(GetCurrentThreadId() == thread_id);
		SuspendThread(hThread);
	}

	void Resume()
	{
		// This SHOULD be called by someone else.
		ASSERT(GetCurrentThreadId() != thread_id);
		if(!ResumeThread(hThread))
		{
			DWORD le = GetLastError();
			printf("lasterror: %u\n", (unsigned int)le);
		}
	}

	void Join()
	{
		WaitForSingleObject(hThread, INFINITE);
	}

	uint32 GetId() { return thread_id; }
};

#else
#ifndef HAVE_DARWIN
#include <semaphore.h>
int GenerateThreadId();

class ThreadController
{
	sem_t sem;
	pthread_t handle;
	int thread_id;
public:
	void Setup(pthread_t h)
	{
		handle = h;
		sem_init(&sem, PTHREAD_PROCESS_PRIVATE, 0);
		thread_id = GenerateThreadId();
	}
	~ThreadController()
	{
		sem_destroy(&sem);
	}

	void Suspend()
	{
		ASSERT(pthread_equal(pthread_self(), handle));
		sem_wait(&sem);
	}

	void Resume()
	{
		ASSERT(!pthread_equal(pthread_self(), handle));
		sem_post(&sem);
	}

	void Join()
	{
		// waits until the thread finishes then returns
		pthread_join(handle, NULL);
	}

	inline uint32 GetId() { return (uint32)thread_id; }
};

#else
int GenerateThreadId();
class ThreadController
{
	pthread_cond_t cond;
	pthread_mutex_t mutex;
	int thread_id;
	pthread_t handle;
public:
	void Setup(pthread_t h)
	{
		handle = h;
		pthread_mutex_init(&mutex,NULL);
		pthread_cond_init(&cond,NULL);
		thread_id = GenerateThreadId();
	}
	~ThreadController()
	{
		pthread_mutex_destroy(&mutex);
		pthread_cond_destroy(&cond);
	}
	void Suspend()
	{
		pthread_cond_wait(&cond, &mutex);
	}
	void Resume()
	{
		pthread_cond_signal(&cond);
	}
	void Join()
	{
		pthread_join(handle,NULL);
	}
	inline uint32 GetId() { return (uint32)thread_id; }
};

#endif

#endif

struct ThreadStruct
{
	ThreadContext * ExecutionTarget;
	ThreadController ControlInterface;
	NativeMutex SetupMutex;
	bool DeleteAfterExit;
};

typedef std::set<ThreadStruct*> ThreadSet;

class CThreadPool
{
	int GetNumCpus();

	uint32 _threadsRequestedSinceLastCheck;
	uint32 _threadsFreedSinceLastCheck;
	uint32 _threadsExitedSinceLastCheck;
	uint32 _threadsToExit;
	int32 _threadsEaten;
	NativeMutex _mutex;

    ThreadSet m_activeThreads;
	ThreadSet m_freeThreads;

public:
	CThreadPool();

	// call every 2 minutes or so.
	void IntegrityCheck(uint8 ThreadCount = THREAD_RESERVE);

	// call at startup
	void Startup(uint8 ThreadCount = 8);

	// shutdown all threads
	void Shutdown();
	
	// return true - suspend ourselves, and wait for a future task.
	// return false - exit, we're shutting down or no longer needed.
	bool ThreadExit(ThreadStruct * t);

	// creates a thread, returns a handle to it.
	ThreadStruct * StartThread(ThreadContext * ExecutionTarget);

	// grabs/spawns a thread, and tells it to execute a task.
	void ExecuteTask(ThreadContext * ExecutionTarget);

	// prints some neat debug stats
	void ShowStats();

	// kills x free threads
	void KillFreeThreads(uint32 count);

	// resets the gobble counter
	inline void Gobble() { _threadsEaten=(int32)m_freeThreads.size(); }

	// gets active thread count
	inline uint32 GetActiveThreadCount() { return (uint32)m_activeThreads.size(); }

	// gets free thread count
	inline uint32 GetFreeThreadCount() { return (uint32)m_freeThreads.size(); }
};

extern CThreadPool ThreadPool;

#endif