Zabbix

/*

** Copyright (C) 2001-2025 Zabbix SIA

**

** This program is free software: you can redistribute it and/or modify it under the terms of

** the GNU Affero General Public License as published by the Free Software Foundation, version 3.

**

** This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;

** without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

** See the GNU Affero General Public License for more details.

**

** You should have received a copy of the GNU Affero General Public License along with this program.

** If not, see <https://www.gnu.org/licenses/>.

**/

#include "zbxtrends.h"

#include "trends.h"

​

#include "zbxalgo.h"

#include "zbxmutexs.h"

#include "zbxshmem.h"

#include "zbxnum.h"

#include "zbxstr.h"

​

typedef struct

{

    zbx_uint64_t        itemid;     /* the itemid */

    int         start;      /* the period start time */

    int         end;        /* the period end time */

    zbx_trend_function_t    function;   /* the trends function */

    zbx_trend_state_t   state;      /* the cached value state */

    double          value;      /* the cached value */

    zbx_uint32_t        prev;       /* index of the previous LRU list or unused entry */

    zbx_uint32_t        next;       /* index of the next LRU list or unused entry */

    zbx_uint32_t        prev_value; /* index of the previous value list */

    zbx_uint32_t        next_value; /* index of the next value list */

}

zbx_tfc_data_t;

​

typedef struct

{

    char        header[ZBX_HASHSET_ENTRY_OFFSET];

    zbx_tfc_data_t  data;

}

zbx_tfc_slot_t;

​

typedef struct

{

    zbx_hashset_t   index;

    zbx_tfc_slot_t  *slots;

    size_t      slots_size;

    zbx_uint32_t    slots_num;

    zbx_uint32_t    free_slot;

    zbx_uint32_t    free_head;

    zbx_uint32_t    lru_head;

    zbx_uint32_t    lru_tail;

    zbx_uint64_t    hits;

    zbx_uint64_t    misses;

    zbx_uint64_t    items_num;

    zbx_uint64_t    conf_size;

}

zbx_tfc_t;

​

static zbx_tfc_t    *cache = NULL;

static int      alloc_num = 0;

​

/*

 * The shared memory is split in three parts:

 *   1) header, containing cache information

 *   2) indexing hashset slots pointer array, allocated during cache initialization

 *   3) slots array, allocated during cache initialization and used for hashset entry allocations

 */

static zbx_shmem_info_t *tfc_mem = NULL;

​

static zbx_mutex_t  tfc_lock = ZBX_MUTEX_NULL;

​

ZBX_SHMEM_FUNC_IMPL(__tfc, tfc_mem)

​

#define LOCK_CACHE  zbx_mutex_lock(tfc_lock)

#define UNLOCK_CACHE    zbx_mutex_unlock(tfc_lock)

​

static void tfc_free_slot(zbx_tfc_slot_t *slot)

{

    zbx_uint32_t    index = slot - cache->slots;

​

    slot->data.next = cache->free_head;

    slot->data.prev = UINT32_MAX;

    cache->free_head = index;

}

​

static zbx_tfc_slot_t   *tfc_alloc_slot(void)

{

    zbx_uint32_t    index;