//
// mp::mempool
//
// Copyright (C) 2008 FURUHASHI Sadayuki
//
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
//
//        http://www.apache.org/licenses/LICENSE-2.0
//
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//

#ifndef MP_MEMPOOL_H__
#define MP_MEMPOOL_H__

#include <stdexcept>
#include <cstdlib>
#include <limits>
#include "mp/utility.h"

#ifndef MP_POOL_DEFAULT_ALLOCATION_SIZE
#define MP_POOL_DEFAULT_ALLOCATION_SIZE 32*1024
#endif

#ifndef MP_POOL_DEFAULT_LOTS_IN_CHUNK
#define MP_POOL_DEFAULT_LOTS_IN_CHUNK 4
#endif

#ifndef MP_POOL_ALLOCATOR_DEFAULT_OBJECTS_IN_CHUNK
#define MP_POOL_ALLOCATOR_DEFAULT_OBJECTS_IN_CHUNK 1024
#endif

namespace mp {

static const size_t POOL_DEFAULT_ALLOCATION_SIZE = MP_POOL_DEFAULT_ALLOCATION_SIZE;
static const size_t POOL_DEFAULT_LOTS_IN_CHUNK = MP_POOL_DEFAULT_LOTS_IN_CHUNK;
static const size_t POOL_ALLOCATOR_DEFAULT_OBJECTS_IN_CHUNK = MP_POOL_ALLOCATOR_DEFAULT_OBJECTS_IN_CHUNK;

template < size_t EstimatedAllocationSize = POOL_DEFAULT_ALLOCATION_SIZE,
	   size_t OptimalLotsInChunk = POOL_DEFAULT_LOTS_IN_CHUNK >
class mempool {
public:
	mempool();
	~mempool();

public:
	//! Allocate memory from the pool.
	/* The allocated memory have to be freed using free() function. */
	inline void* malloc(size_t size);

	//! Free the allocated memory.
	inline void free(void* x);

	//! Template version of malloc()
	template <size_t size>
		inline void* malloc();

public:
	//! Destroy the constructed object.
	template <typename T>
		inline void destroy(T* x);

	//! Allocate memory from the pool and construct object.
	template <typename T>
		inline T* construct();
MP_ARGS_BEGIN
	template <typename T, MP_ARGS_TEMPLATE>
		inline T* construct(MP_ARGS_PARAMS);
MP_ARGS_END

private:
	struct chunk_t {
		chunk_t* next;
		chunk_t* prev;
		size_t free;
		size_t lots;
		size_t size;
	};
	struct data_t {
		chunk_t* chunk;
	};

private:
	chunk_t* m_free;
	chunk_t* m_used;

private:
	void* expand_free(size_t req);
	void splice_to_used(chunk_t* chunk);
	void splice_to_free(chunk_t* chunk);

private:
	mempool(const mempool&);
};


template < typename ThreadTag = main_thread_tag,
	   size_t EstimatedAllocationSize = POOL_DEFAULT_ALLOCATION_SIZE,
	   size_t OptimalLotsInChunk = POOL_DEFAULT_LOTS_IN_CHUNK >
class singleton_mempool {
public:
	typedef mempool<EstimatedAllocationSize, OptimalLotsInChunk> pool_type;

	static void* malloc(size_t size)
		{ return pool().malloc(size); }

	static void free(void* x)
		{ pool().free(x); }

	template <size_t size>
	static void* malloc()
		{ return pool().malloc<size>(); }

public:
	template <typename T>
	static void destroy(T* x)
		{ return pool().destroy<T>(x); }

	template <typename T>
	static T* construct()
		{ return pool().construct<T>(); }
MP_ARGS_BEGIN
	template <typename T, MP_ARGS_TEMPLATE>
	static T* construct(MP_ARGS_PARAMS)
		{ return pool().construct<T, MP_ARGS_TYPES>(MP_ARGS_FUNC); }
MP_ARGS_END

private:
	static pool_type& pool()
	{
		static pool_type object;
		return object;
	}
};


template < typename T,
		typename ThreadTag = main_thread_tag,
		size_t OptimalObjectsInChunk = POOL_ALLOCATOR_DEFAULT_OBJECTS_IN_CHUNK >
class mempool_allocator {
private:
	typedef singleton_mempool<ThreadTag, sizeof(T), OptimalObjectsInChunk> pool;

public:
	typedef size_t size_type;
	typedef ptrdiff_t difference_type;
	typedef T* pointer;
	typedef const T* const_pointer;
	typedef T& reference;
	typedef const T& const_reference;
	typedef T value_type;

	template <class U>
	struct rebind { typedef mempool_allocator<U> other; };

	mempool_allocator() throw() {}
	mempool_allocator(const mempool_allocator&) throw() {}
	template <class U> mempool_allocator(const mempool_allocator<U>&) throw() {}

	~mempool_allocator() throw() {}

	pointer address(reference r)
		{ return &r; }

	const_pointer address(const_reference s)
		{ return &s; }

	size_type max_size() throw()
		{ return std::numeric_limits<size_t>::max() / sizeof(T); }

	pointer allocate(size_type num, const_pointer hint = 0)
	{
		const pointer p = static_cast<pointer>( pool::malloc(sizeof(T) * num) );
		if (p == 0) { throw std::bad_alloc(); }
		return p;
	}

	void deallocate(pointer p, size_type num)
	{
		if(p == 0) { return; }
		pool::free(p);
	}

	void construct(pointer p, const T& r)
		{ new ( reinterpret_cast<void*>(p) ) T(r); }

	void destroy(pointer p)
		{ p->~T(); }
};


}  // namespace mp

template <class T1, class T2>
bool operator==(const mp::mempool_allocator<T1>&, const mp::mempool_allocator<T2>&) throw() { return true; }

template <class T1, class T2>
bool operator!=(const mp::mempool_allocator<T1>&, const mp::mempool_allocator<T2>&) throw() { return false; }

#include "mp/mempool_impl.h"

#endif /* mp/mempool.h */