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/*
* Copyright 2010 Marek Olšák <maraeo@gmail.com>
* Copyright 2016 Advanced Micro Devices, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* on the rights to use, copy, modify, merge, publish, distribute, sub
* license, and/or sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
* THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
* USE OR OTHER DEALINGS IN THE SOFTWARE. */
#include "slab.h"
#include "macros.h"
#include "simple_list.h"
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#define ALIGN(value, align) (((value) + (align) - 1) & ~((align) - 1))
#ifdef DEBUG
#define SLAB_MAGIC 0xcafe4321
#define SET_MAGIC(element) (element)->magic = SLAB_MAGIC
#define CHECK_MAGIC(element) assert((element)->magic == SLAB_MAGIC)
#else
#define SET_MAGIC(element)
#define CHECK_MAGIC(element)
#endif
/* One array element within a big buffer. */
struct slab_element_header {
/* The next free element. */
struct slab_element_header *next_free;
#ifdef DEBUG
/* Use intptr_t to keep the header aligned to a pointer size. */
intptr_t magic;
#endif
};
static struct slab_element_header *
slab_get_element(struct slab_mempool *pool,
struct slab_page_header *page, unsigned index)
{
return (struct slab_element_header*)
((uint8_t*)&page[1] + (pool->element_size * index));
}
static bool
slab_add_new_page(struct slab_mempool *pool)
{
struct slab_page_header *page;
struct slab_element_header *element;
unsigned i;
page = malloc(sizeof(struct slab_page_header) +
pool->num_elements * pool->element_size);
if (!page)
return false;
if (!pool->list.prev)
make_empty_list(&pool->list);
insert_at_tail(&pool->list, page);
/* Mark all elements as free. */
for (i = 0; i < pool->num_elements-1; i++) {
element = slab_get_element(pool, page, i);
element->next_free = slab_get_element(pool, page, i + 1);
SET_MAGIC(element);
}
element = slab_get_element(pool, page, pool->num_elements - 1);
element->next_free = pool->first_free;
SET_MAGIC(element);
pool->first_free = slab_get_element(pool, page, 0);
return true;
}
/**
* Allocate an object from the slab. Single-threaded (no mutex).
*/
void *
slab_alloc_st(struct slab_mempool *pool)
{
struct slab_element_header *element;
/* Allocate a new page. */
if (!pool->first_free &&
!slab_add_new_page(pool))
return NULL;
element = pool->first_free;
CHECK_MAGIC(element);
pool->first_free = element->next_free;
return &element[1];
}
/**
* Free an object allocated from the slab. Single-threaded (no mutex).
*/
void
slab_free_st(struct slab_mempool *pool, void *ptr)
{
struct slab_element_header *element =
((struct slab_element_header*)ptr - 1);
CHECK_MAGIC(element);
element->next_free = pool->first_free;
pool->first_free = element;
}
/**
* Allocate an object from the slab. Thread-safe.
*/
void *
slab_alloc_mt(struct slab_mempool *pool)
{
void *mem;
mtx_lock(&pool->mutex);
mem = slab_alloc_st(pool);
mtx_unlock(&pool->mutex);
return mem;
}
/**
* Free an object allocated from the slab. Thread-safe.
*/
void
slab_free_mt(struct slab_mempool *pool, void *ptr)
{
mtx_lock(&pool->mutex);
slab_free_st(pool, ptr);
mtx_unlock(&pool->mutex);
}
void
slab_destroy(struct slab_mempool *pool)
{
struct slab_page_header *page, *temp;
if (pool->list.next) {
foreach_s(page, temp, &pool->list) {
remove_from_list(page);
free(page);
}
}
mtx_destroy(&pool->mutex);
}
/**
* Create an allocator for same-sized objects.
*
* \param item_size Size of one object.
* \param num_items Number of objects to allocate at once.
*/
void
slab_create(struct slab_mempool *pool,
unsigned item_size,
unsigned num_items)
{
mtx_init(&pool->mutex, mtx_plain);
pool->element_size = ALIGN(sizeof(struct slab_element_header) + item_size,
sizeof(intptr_t));
pool->num_elements = num_items;
pool->first_free = NULL;
}
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