mempool.c

#include "mempool.h"

#include <stdlib.h>

void
mempool_new(struct hmd_mempool *pool)
{
	struct hmd_mempool_chunk *chunk;
	chunk = malloc(sizeof(struct hmd_mempool_chunk));
	chunk->prev = NULL;
	chunk->next = NULL;
	chunk->available = CHUNK_SIZE;
	
	pool->chunks = chunk;
	pool->larges = NULL;
}

void
mempool_destory(struct hmd_mempool *pool)
{
	struct hmd_mempool_chunk *chunk_iter = pool->chunks;
	while (chunk_iter != NULL) {
		struct hmd_mempool_chunk *tmp = chunk_iter;
		chunk_iter = chunk_iter->next;
		free(tmp);
	}

	struct hmd_mempool_large *large_iter = pool->larges;
	while (large_iter != NULL) {
		struct hmd_mempool_large *tmp = large_iter;
		large_iter = large_iter->next;
		free(tmp->data);
		free(tmp);
	}
}

static struct hmd_mempool_chunk*
insert_chunk_to_list(
	struct hmd_mempool_chunk *list,
	struct hmd_mempool_chunk *chunk)
{
	struct hmd_mempool_chunk *iter = list;
	while(iter->next != NULL && (iter->available > chunk->available))
		iter = iter->next;
	
	chunk->next = iter;
	chunk->prev = iter->prev;
	chunk->prev->next = chunk;
	iter->prev = chunk;

	return chunk->prev == NULL?chunk:list;
}

void*
mempool_alloc(struct hmd_mempool *pool,int size)
{
	if (size > CHUNK_SIZE/4) {
		void *data = malloc(size);
		if (data == NULL) return NULL;
		
		struct hmd_mempool_large *new_large;
		new_large = malloc(struct hmd_mempool_large);
		new_large->data = data;		
		new_large->next = pool->larges;
		new_large->prev = NULL;
		
		pool->larges->prev = new_large;
		pool->larges = new_large;

		return data;
	} else {
		struct hmd_mempool_chunk *chunk,*list;
		if(pool->chunks->available > size){
			chunk = pool->chunks;
			list = chunk->next;
			list->prev = NULL;
		} else {
			chunk = malloc(sizeof(struct hmd_mempool_chunk));
			if (chunk == NULL) return NULL;
			list = pool->chunks;
		}
		
		void *ret = (void*)chunk->curr;
		chunk->curr += size;
		list = insert_chunk_to_list(list,chunk);
		pool->chunks = list;

		return ret;
	}
}

mempool.h

#ifndef __HMD_MEMPOOL_H__
#define __HMD_MEMPOOL_H__

#define CHUNK_SIZE = 4096

struct hmd_mempool_chunk
{
	struct hmd_mempool_chunk *prev,*next;
	unsigned char data[CHUNK_SIZE];
	unsigned char *curr;
	int available;
};

struct hmd_mempool_large
{
	struct hmd_mempool_large *prev,*next;
	void *data;
};

struct hmd_mempool
{
	struct hmd_mempool_chunk *chunks;
	struct hmd_mempool_large *larges;
};

void mempool_new(struct hmd_mempool *pool);
void mempool_destroy(struct hmd_mempool *pool);
void* mempool_alloc(struct hmd_mempool *pool,int size);

#endif // __HMD_MEMPOOL_H__