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/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
* SPDX-License-Identifier: GPL-3.0-or-later
*/
#pragma once
#include <stdint.h>
#include <libknot/db/db.h>
/* Cache options. */
struct kr_cdb_opts {
const char *path; /*!< Cache URI path. */
size_t maxsize; /*!< Suggested cache size in bytes; pass 0 to keep unchanged/default. */
};
struct kr_cdb_stats {
uint64_t open;
uint64_t close;
uint64_t count;
uint64_t count_entries;
uint64_t clear;
uint64_t commit;
uint64_t read;
uint64_t read_miss;
uint64_t write;
uint64_t remove;
uint64_t remove_miss;
uint64_t match;
uint64_t match_miss;
uint64_t read_leq;
uint64_t read_leq_miss;
double usage_percent;
};
/*! Pointer to a cache structure.
*
* This struct is opaque and never defined; the purpose is to get better
* type safety than with void *.
*/
typedef struct kr_cdb *kr_cdb_pt;
/*! Cache database API.
* This is a simplified version of generic DB API from libknot,
* that is tailored to caching purposes.
*/
struct kr_cdb_api {
const char *name;
/* Context operations */
int (*open)(kr_cdb_pt *db, struct kr_cdb_stats *stat, struct kr_cdb_opts *opts, knot_mm_t *mm);
void (*close)(kr_cdb_pt db, struct kr_cdb_stats *stat);
int (*count)(kr_cdb_pt db, struct kr_cdb_stats *stat);
int (*clear)(kr_cdb_pt db, struct kr_cdb_stats *stat);
/** Run after a row of operations to release transaction/lock if needed. */
int (*commit)(kr_cdb_pt db, struct kr_cdb_stats *stat);
/* Data access */
int (*read)(kr_cdb_pt db, struct kr_cdb_stats *stat,
const knot_db_val_t *key, knot_db_val_t *val, int maxcount);
int (*write)(kr_cdb_pt db, struct kr_cdb_stats *stat, const knot_db_val_t *key,
knot_db_val_t *val, int maxcount);
/** Remove maxcount keys.
* \returns the number of successfully removed keys or the first error code
* It returns on first error, but ENOENT is not considered an error. */
int (*remove)(kr_cdb_pt db, struct kr_cdb_stats *stat,
knot_db_val_t keys[], int maxcount);
/* Specialised operations */
/** Find key-value pairs that are prefixed by the given key, limited by maxcount.
* \return the number of pairs or negative error. */
int (*match)(kr_cdb_pt db, struct kr_cdb_stats *stat,
knot_db_val_t *key, knot_db_val_t keyval[][2], int maxcount);
/** Less-or-equal search (lexicographic ordering).
* On successful return, key->data and val->data point to DB-owned data.
* return: 0 for equality, > 0 for less, < 0 kr_error */
int (*read_leq)(kr_cdb_pt db, struct kr_cdb_stats *stat,
knot_db_val_t *key, knot_db_val_t *val);
/** Return estimated space usage (0--100). */
double (*usage_percent)(kr_cdb_pt db);
/** Return the current cache size limit in bytes; could be cached by check_health(). */
size_t (*get_maxsize)(kr_cdb_pt db);
/** Perform maintenance.
* In LMDB case it checks whether data.mdb is still the same
* and reopens it if it isn't; it errors out if the file doesn't exist anymore.
* \return 0 if OK, 1 if reopened OK, < 0 kr_error */
int (*check_health)(kr_cdb_pt db, struct kr_cdb_stats *stat);
};
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