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/*
** 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/>.
**/
#ifndef ZABBIX_CACHEVALUE_H
#define ZABBIX_CACHEVALUE_H
#include "zbxtypes.h"
#include "zbxalgo.h"
#include "zbxhistory.h"
#include "zbxshmem.h"
/*
* The Value Cache provides read caching of item historical data residing in history
* tables. No components must read history tables manually. Instead all history data
* must be read from the Value Cache.
*
* Usage notes:
*
* Initialization
*
* The value cache must be initialized at the start of the program with zbx_vc_init()
* function. To ensure proper removal of shared memory the value cache must be destroyed
* upon a program exit with zbx_vc_destroy() function.
*
* Adding data
*
* Whenever a new item value is added to system (history tables) the item value must be
* also added added to Value Cache with zbx_dc_add_value() function to keep it up to date.
*
* Retrieving data
*
* The history data is accessed with zbx_vc_get_values() and zbx_vc_get_value()
* functions. Afterwards the retrieved history data must be freed by the caller by using
* either zbx_history_record_vector_destroy() function (free the zbx_vc_get_values()
* call output) or zbx_history_record_clear() function (free the zbx_vc_get_value() call output).
*
* Locking
*
* The cache ensures synchronization between processes by using automatic locks whenever
* a cache function (zbx_vc_*) is called and by providing manual cache locking functionality
* with zbx_vc_lock()/zbx_vc_unlock() functions.
*
*/
#define ZBX_VC_MODE_NORMAL 0
#define ZBX_VC_MODE_LOWMEM 1
/* indicates that all values from database are cached */
#define ZBX_ITEM_STATUS_CACHED_ALL 1
/* the cache statistics */
typedef struct
{
/* Value cache misses are new values cached during request and hits are calculated by */
/* subtracting misses from the total number of values returned (0 if the number of */
/* returned values is less than misses. */
/* When performing count based requests the number of cached values might be greater */
/* than number of returned values. This can skew the hits/misses ratio towards misses. */
zbx_uint64_t hits;
zbx_uint64_t misses;
zbx_uint64_t total_size;
zbx_uint64_t free_size;
/* value cache operating mode - see ZBX_VC_MODE_* defines */
int mode;
}
zbx_vc_stats_t;
/* item diagnostic statistics */
typedef struct
{
zbx_uint64_t itemid;
int values_num;
int hourly_num;
}
zbx_vc_item_stats_t;
ZBX_PTR_VECTOR_DECL(vc_item_stats_ptr, zbx_vc_item_stats_t *)
void zbx_vc_item_stats_free(zbx_vc_item_stats_t *vc_item_stats);
int zbx_vc_init(zbx_uint64_t value_cache_size, char **error);
void zbx_vc_destroy(void);
void zbx_vc_reset(void);
void zbx_vc_enable(void);
void zbx_vc_disable(void);
int zbx_vc_get_values(zbx_uint64_t itemid, unsigned char value_type, zbx_vector_history_record_t *values,
int seconds, int count, const zbx_timespec_t *ts);
int zbx_vc_get_value(zbx_uint64_t itemid, unsigned char value_type, const zbx_timespec_t *ts,
zbx_history_record_t *value);
int zbx_vc_add_values(zbx_vector_dc_history_ptr_t *history, int *ret_flush, int config_history_storage_pipelines);
int zbx_vc_get_statistics(zbx_vc_stats_t *stats);
void zbx_vc_remove_items_by_ids(zbx_vector_uint64_t *itemids);
void zbx_vc_get_diag_stats(zbx_uint64_t *items_num, zbx_uint64_t *values_num, int *mode);
void zbx_vc_get_mem_stats(zbx_shmem_stats_t *mem);
void zbx_vc_get_item_stats(zbx_vector_vc_item_stats_ptr_t *stats);
void zbx_vc_flush_stats(void);
void zbx_vc_add_new_items(const zbx_vector_uint64_pair_t *items);
#endif
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