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/* Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#pragma once
#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. */
};
/*! 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)(knot_db_t **db, struct kr_cdb_opts *opts, knot_mm_t *mm);
void (*close)(knot_db_t *db);
int (*count)(knot_db_t *db);
int (*clear)(knot_db_t *db);
/** Run after a row of operations to release transaction/lock if needed. */
int (*sync)(knot_db_t *db);
/* Data access */
int (*read)(knot_db_t *db, const knot_db_val_t *key, knot_db_val_t *val,
int maxcount);
int (*write)(knot_db_t *db, const knot_db_val_t *key, knot_db_val_t *val,
int maxcount);
/** Remove maxcount keys.
* \returns the number of succesfully removed keys or the first error code
* It returns on first error, but ENOENT is not considered an error. */
int (*remove)(knot_db_t *db, 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)(knot_db_t *db, knot_db_val_t *key, knot_db_val_t keyval[][2], int maxcount);
/** Not implemented ATM. */
int (*prune)(knot_db_t *db, 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)(knot_db_t *db, knot_db_val_t *key, knot_db_val_t *val);
};
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