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/*
 * Copyright (C) 2006 Ondrej Palkovsky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * 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.
 */

#ifndef __SLAB_H__
#define __SLAB_H__

#include <list.h>
#include <synch/spinlock.h>
#include <arch/atomic.h>

/** Initial Magazine size (TODO: dynamically growing magazines) */
#define SLAB_MAG_SIZE  4

/** If object size is less, store control structure inside SLAB */
#define SLAB_INSIDE_SIZE   (PAGE_SIZE >> 3)

/** Maximum wasted space we allow for cache */
#define SLAB_MAX_BADNESS(cache)   ((PAGE_SIZE << (cache)->order >> 2))

/* slab_reclaim constants */
#define SLAB_RECLAIM_ALL  0x1 /**< Reclaim all possible memory, because
                   *   we are in memory stress */

/* cache_create flags */
#define SLAB_CACHE_NOMAGAZINE 0x1 /**< Do not use per-cpu cache */
#define SLAB_CACHE_SLINSIDE   0x2 /**< Have control structure inside SLAB */

typedef struct {
    link_t link;
    count_t busy;  /**< Count of full slots in magazine */
    count_t size;  /**< Number of slots in magazine */
    void *objs[0]; /**< Slots in magazine */
}slab_magazine_t;

typedef struct {
    char *name;

    SPINLOCK_DECLARE(lock);
    link_t link;
    /* Configuration */
    size_t size;      /**< Size of SLAB position - align_up(sizeof(obj)) */
    int (*constructor)(void *obj, int kmflag);
    void (*destructor)(void *obj);
    int flags;        /**< Flags changing behaviour of cache */

    /* Computed values */
    __u8 order;        /**< Order of frames to be allocated */
    int objects;      /**< Number of objects that fit in */

    /* Statistics */
    atomic_t allocated_slabs;
    atomic_t allocated_objs;

    /* Slabs */
    link_t full_slabs;     /**< List of full slabs */
    link_t partial_slabs;  /**< List of partial slabs */
    /* Magazines  */
    link_t magazines;      /**< List o full magazines */

    /** CPU cache */
    struct {
        slab_magazine_t *current;
        slab_magazine_t *last;
        SPINLOCK_DECLARE(lock);
    }mag_cache[0];
}slab_cache_t;

extern slab_cache_t * slab_cache_create(char *name,
                    size_t size,
                    size_t align,
                    int (*constructor)(void *obj, int kmflag),
                    void (*destructor)(void *obj),
                    int flags);
extern void slab_cache_destroy(slab_cache_t *cache);

extern void * slab_alloc(slab_cache_t *cache, int flags);
extern void slab_free(slab_cache_t *cache, void *obj);
extern count_t slab_reclaim(int flags);

/** Initialize SLAB subsytem */
extern void slab_cache_init(void);

/* KConsole debug */
extern void slab_print_list(void);

#endif