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Diffstat (limited to '')
| -rw-r--r-- | lib/cache/api.h | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/lib/cache/api.h b/lib/cache/api.h new file mode 100644 index 0000000..61bf796 --- /dev/null +++ b/lib/cache/api.h @@ -0,0 +1,201 @@ +/* Copyright (C) 2014-2017 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/consts.h> +#include <libknot/rrset.h> +#include <sys/time.h> +#include "lib/cache/cdb_api.h" +#include "lib/defines.h" +#include "contrib/ucw/config.h" /*uint*/ + +/** When knot_pkt is passed from cache without ->wire, this is the ->size. */ +static const size_t PKT_SIZE_NOWIRE = -1; + + +#include "lib/module.h" +/* Prototypes for the 'cache' module implementation. */ +int cache_peek(kr_layer_t *ctx, knot_pkt_t *pkt); +int cache_stash(kr_layer_t *ctx, knot_pkt_t *pkt); + + +/** + * Cache structure, keeps API, instance and metadata. + */ +struct kr_cache +{ + knot_db_t *db; /**< Storage instance */ + const struct kr_cdb_api *api; /**< Storage engine */ + struct { + uint32_t hit; /**< Number of cache hits */ + uint32_t miss; /**< Number of cache misses */ + uint32_t insert; /**< Number of insertions */ + uint32_t delete; /**< Number of deletions */ + } stats; + + uint32_t ttl_min, ttl_max; /**< TTL limits */ + + /* A pair of stamps for detection of real-time shifts during runtime. */ + struct timeval checkpoint_walltime; /**< Wall time on the last check-point. */ + uint64_t checkpoint_monotime; /**< Monotonic milliseconds on the last check-point. */ +}; + +/** + * Open/create cache with provided storage options. + * @param cache cache structure to be initialized + * @param api storage engine API + * @param opts storage-specific options (may be NULL for default) + * @param mm memory context. + * @return 0 or an error code + */ +KR_EXPORT +int kr_cache_open(struct kr_cache *cache, const struct kr_cdb_api *api, struct kr_cdb_opts *opts, knot_mm_t *mm); + +/** + * Path to cache file to remove on critical out-of-space error. (do NOT modify it) + */ +KR_EXPORT extern +const char *kr_cache_emergency_file_to_remove; + +/** + * Close persistent cache. + * @note This doesn't clear the data, just closes the connection to the database. + * @param cache structure + */ +KR_EXPORT +void kr_cache_close(struct kr_cache *cache); + +/** Run after a row of operations to release transaction/lock if needed. */ +KR_EXPORT +int kr_cache_sync(struct kr_cache *cache); + +/** + * Return true if cache is open and enabled. + */ +static inline bool kr_cache_is_open(struct kr_cache *cache) +{ + return cache->db != NULL; +} + +/** (Re)set the time pair to the current values. */ +static inline void kr_cache_make_checkpoint(struct kr_cache *cache) +{ + cache->checkpoint_monotime = kr_now(); + gettimeofday(&cache->checkpoint_walltime, NULL); +} + +/** + * Insert RRSet into cache, replacing any existing data. + * @param cache cache structure + * @param rr inserted RRSet + * @param rrsig RRSIG for inserted RRSet (optional) + * @param rank rank of the data + * @param timestamp current time + * @return 0 or an errcode + */ +KR_EXPORT +int kr_cache_insert_rr(struct kr_cache *cache, const knot_rrset_t *rr, const knot_rrset_t *rrsig, uint8_t rank, uint32_t timestamp); + +/** + * Clear all items from the cache. + * @param cache cache structure + * @return 0 or an errcode + */ +KR_EXPORT +int kr_cache_clear(struct kr_cache *cache); + + +/* ** This interface is temporary. ** */ + +struct kr_cache_p { + uint32_t time; /**< The time of inception. */ + uint32_t ttl; /**< TTL at inception moment. Assuming it fits into int32_t ATM. */ + uint8_t rank; /**< See enum kr_rank */ + struct { + /* internal: pointer to eh struct */ + void *raw_data, *raw_bound; + }; +}; +KR_EXPORT +int kr_cache_peek_exact(struct kr_cache *cache, const knot_dname_t *name, uint16_t type, + struct kr_cache_p *peek); +/* Parameters (qry, name, type) are used for timestamp and stale-serving decisions. */ +KR_EXPORT +int32_t kr_cache_ttl(const struct kr_cache_p *peek, const struct kr_query *qry, + const knot_dname_t *name, uint16_t type); + +KR_EXPORT +int kr_cache_materialize(knot_rdataset_t *dst, const struct kr_cache_p *ref, + knot_mm_t *pool); + + +/** + * Remove an entry from cache. + * @param cache cache structure + * @param name dname + * @param type rr type + * @return number of deleted records, or negative error code + * @note only "exact hits" are considered ATM, and + * some other information may be removed alongside. + */ +KR_EXPORT +int kr_cache_remove(struct kr_cache *cache, const knot_dname_t *name, uint16_t type); + +/** + * Get keys matching a dname lf prefix + * @param cache cache structure + * @param name dname + * @param exact_name whether to only consider exact name matches + * @param keyval matched key-value pairs + * @param maxcount limit on the number of returned key-value pairs + * @return result count or an errcode + * @note the cache keys are matched by prefix, i.e. it very much depends + * on their structure; CACHE_KEY_DEF. + */ +KR_EXPORT +int kr_cache_match(struct kr_cache *cache, const knot_dname_t *name, + bool exact_name, knot_db_val_t keyval[][2], int maxcount); + +/** + * Remove a subtree in cache. It's like _match but removing them instead of returning. + * @return number of deleted entries or an errcode + */ +KR_EXPORT +int kr_cache_remove_subtree(struct kr_cache *cache, const knot_dname_t *name, + bool exact_name, int maxcount); + +/** + * Find the closest cached zone apex for a name (in cache). + * @param is_DS start searching one name higher + * @return the number of labels to remove from the name, or negative error code + * @note timestamp is found by a syscall, and stale-serving is not considered + */ +KR_EXPORT +int kr_cache_closest_apex(struct kr_cache *cache, const knot_dname_t *name, bool is_DS, + knot_dname_t **apex); + +/** + * Unpack dname and type from db key + * @param key db key representation + * @param buf output buffer of domain name in dname format + * @param type output for type + * @return length of dname or an errcode + * @note only "exact hits" are considered ATM, moreover xNAME records + * are "hidden" as NS. (see comments in struct entry_h) + */ +KR_EXPORT +int kr_unpack_cache_key(knot_db_val_t key, knot_dname_t *buf, uint16_t *type); |