/*
 * $Id$
 *
    Copyright (c) 2006-2019 Chung, Hyung-Hwan. All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:
    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.

    THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR
    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
    OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
    IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
    NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
    THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <qse/cmn/Mpool.hpp>
#include <qse/cmn/mem.h>

/////////////////////////////////
QSE_BEGIN_NAMESPACE(QSE)
/////////////////////////////////

Mpool::Mpool (Mmgr* mmgr, qse_size_t datum_size, qse_size_t block_size): Mmged(mmgr)
{
	if (datum_size > 0 && datum_size < QSE_SIZEOF(void*))
		datum_size = QSE_SIZEOF(void*);

	this->mp_blocks  = QSE_NULL;
	this->free_list  = QSE_NULL;
	this->datum_size = datum_size;
	this->block_size = block_size;
#if defined(QSE_DEBUG_MPOOL)
	this->navail = 0;
	this->nalloc = 0;
#endif
}

Mpool::~Mpool ()
{
	this->dispose ();
}

void* Mpool::allocate ()
{
	if (this->datum_size <= 0 || this->block_size <= 0) return QSE_NULL;

	void* ptr = this->free_list;
	if (!ptr) 
	{
		// NOTE: 'return QSE_NULL' can't be reached if add_block()
		//       raises an exception.
		if (!this->add_block ()) return QSE_NULL; 
		ptr = this->free_list;
	}
	this->free_list = this->free_list->next;
#if defined(QSE_DEBUG_MPOOL)
	this->navail--;
#endif
	return ptr;
}

void Mpool::dispose (void* ptr)
{
	((Chain*)ptr)->next = this->free_list;
	this->free_list = (Chain*)ptr;
#if defined(QSE_DEBUG_MPOOL)
	this->navail++;
#endif
}

void Mpool::dispose ()
{
	Block* block = this->mp_blocks;
	while (block) 
	{
		Block* next = block->next;

		//::delete[] (qse_uint8_t*)block;
		this->getMmgr()->dispose ((qse_uint8_t*)block);

		block = next;
	}

	this->free_list = QSE_NULL;
	this->mp_blocks = QSE_NULL;

#if defined(QSE_DEBUG_MPOOL)
	this->navail = 0;
	this->nalloc = 0;
#endif
}

Mpool::Block* Mpool::add_block ()
{
	QSE_ASSERT (this->datum_size > 0 && this->block_size > 0);

	//Block* block = (Block*)::new qse_uint8_t[
	//	QSE_SIZEOF(Block) + this->block_size * this->datum_size];
	Block* block = (Block*)this->getMmgr()->allocate (QSE_SIZEOF(Block) + this->block_size * this->datum_size);
	if (!block) return QSE_NULL; // this line may not be reached if the allocator raises an exception

	//this->free_list = (Chain*)block->data;
	this->free_list = (Chain*)(block + 1);
	Chain* ptr = this->free_list;
	for (qse_size_t i = 0; i < this->block_size - 1; i++) 
	{
		Chain* next = (Chain*)((qse_uint8_t*)ptr + this->datum_size);
		ptr->next = next;
		ptr = next;
	}
	ptr->next = QSE_NULL;

	block->next = this->mp_blocks;
	this->mp_blocks = block;

#if defined(QSE_DEBUG_MPOOL)
	this->navail += this->block_size;
	this->nalloc += this->block_size;
#endif

	return block;
}

int Mpool::swap (Mpool& mpool)
{
	// this function is sensitive to member variables changes.
	// whenever you add new member variables, this function require
	// relevant changes.

	if (this->getMmgr() != mpool.getMmgr()) 
	{
		// disallow to swap contents if memory managers are different.
		return -1;
	}

	if (this != &mpool)
	{
	#if defined(QSE_DEBUG_MPOOL)
		qse_size_t org_nalloc = this->nalloc;
		qse_size_t org_navail = this->navail;

		this->nalloc = mpool.nalloc;
		this->navail = mpool.navail;

		mpool.nalloc = org_nalloc;
		mpool.navail = org_navail;
	#endif

		Block* org_mp_blocks = this->mp_blocks;
		Chain* org_free_list = this->free_list;
		qse_size_t org_datum_size = this->datum_size;
		qse_size_t org_block_size = this->block_size;

		this->mp_blocks = mpool.mp_blocks;
		this->free_list = mpool.free_list;
		this->datum_size = mpool.datum_size;
		this->block_size = mpool.block_size;

		mpool.mp_blocks = org_mp_blocks;
		mpool.free_list = org_free_list;
		mpool.datum_size = org_datum_size;
		mpool.block_size = org_block_size;
	}

	return 0;
}

/////////////////////////////////
QSE_END_NAMESPACE(QSE)
/////////////////////////////////

void* operator new (qse_size_t size, QSE::Mpool* mp)
{
	if (mp->isEnabled())
	{
		QSE_ASSERTX (size == mp->getDatumSize(), 
		             "Pass the right allocation size for the given memory pool");
		// the size argument is not really used. you must make sure that
		// the given size matches the datum size of the memory pool.
		if (size != mp->getDatumSize()) 
		{
			// when the assertion above is excluded during the build,
			// bypass the memory pool if a wrong size is passed in.
			// debug your application properly so that this block
			// is never reached.
			goto use_mmgr;
		}
		return mp->allocate();
	}
	else
	{
	use_mmgr:
		// when the memory pool is not enabled, it goes through 
		// the memory manager directly and it honors the size argument.
		//return ::operator new(size, mp->getMmgr());
		return mp->getMmgr()->allocate(size);
	}
}

#if defined(QSE_CPP_NO_OPERATOR_DELETE_OVERLOADING)
void qse_operator_delete (void* ptr, QSE::Mpool* mp)
#else
void operator delete (void* ptr, QSE::Mpool* mp)
#endif
{
	if (mp->isEnabled()) mp->dispose(ptr);
	else mp->getMmgr()->dispose(ptr);
}

void* operator new (qse_size_t size, QSE::Mpool* mp, void* existing_ptr)
{
	return existing_ptr;
}